1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 #ifdef HAVE_conditional_execution
172 #ifndef REVERSE_CONDEXEC_PREDICATES_P
173 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
177 /* The obstack on which the flow graph components are allocated. */
179 struct obstack flow_obstack;
180 static char *flow_firstobj;
182 /* Number of basic blocks in the current function. */
186 /* Number of edges in the current function. */
190 /* The basic block array. */
192 varray_type basic_block_info;
194 /* The special entry and exit blocks. */
196 struct basic_block_def entry_exit_blocks[2]
199 NULL, /* head_tree */
203 NULL, /* local_set */
204 NULL, /* cond_local_set */
205 NULL, /* global_live_at_start */
206 NULL, /* global_live_at_end */
208 ENTRY_BLOCK, /* index */
216 NULL, /* head_tree */
220 NULL, /* local_set */
221 NULL, /* cond_local_set */
222 NULL, /* global_live_at_start */
223 NULL, /* global_live_at_end */
225 EXIT_BLOCK, /* index */
232 /* Nonzero if the second flow pass has completed. */
235 /* Maximum register number used in this function, plus one. */
239 /* Indexed by n, giving various register information */
241 varray_type reg_n_info;
243 /* Size of a regset for the current function,
244 in (1) bytes and (2) elements. */
249 /* Regset of regs live when calls to `setjmp'-like functions happen. */
250 /* ??? Does this exist only for the setjmp-clobbered warning message? */
252 regset regs_live_at_setjmp;
254 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
255 that have to go in the same hard reg.
256 The first two regs in the list are a pair, and the next two
257 are another pair, etc. */
260 /* Callback that determines if it's ok for a function to have no
261 noreturn attribute. */
262 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
264 /* Set of registers that may be eliminable. These are handled specially
265 in updating regs_ever_live. */
267 static HARD_REG_SET elim_reg_set;
269 /* The basic block structure for every insn, indexed by uid. */
271 varray_type basic_block_for_insn;
273 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
274 /* ??? Should probably be using LABEL_NUSES instead. It would take a
275 bit of surgery to be able to use or co-opt the routines in jump. */
277 static rtx label_value_list;
278 static rtx tail_recursion_label_list;
280 /* Holds information for tracking conditional register life information. */
281 struct reg_cond_life_info
283 /* A boolean expression of conditions under which a register is dead. */
285 /* Conditions under which a register is dead at the basic block end. */
288 /* A boolean expression of conditions under which a register has been
292 /* ??? Could store mask of bytes that are dead, so that we could finally
293 track lifetimes of multi-word registers accessed via subregs. */
296 /* For use in communicating between propagate_block and its subroutines.
297 Holds all information needed to compute life and def-use information. */
299 struct propagate_block_info
301 /* The basic block we're considering. */
304 /* Bit N is set if register N is conditionally or unconditionally live. */
307 /* Bit N is set if register N is set this insn. */
310 /* Element N is the next insn that uses (hard or pseudo) register N
311 within the current basic block; or zero, if there is no such insn. */
314 /* Contains a list of all the MEMs we are tracking for dead store
318 /* If non-null, record the set of registers set unconditionally in the
322 /* If non-null, record the set of registers set conditionally in the
324 regset cond_local_set;
326 #ifdef HAVE_conditional_execution
327 /* Indexed by register number, holds a reg_cond_life_info for each
328 register that is not unconditionally live or dead. */
329 splay_tree reg_cond_dead;
331 /* Bit N is set if register N is in an expression in reg_cond_dead. */
335 /* The length of mem_set_list. */
336 int mem_set_list_len;
338 /* Non-zero if the value of CC0 is live. */
341 /* Flags controling the set of information propagate_block collects. */
345 /* Maximum length of pbi->mem_set_list before we start dropping
346 new elements on the floor. */
347 #define MAX_MEM_SET_LIST_LEN 100
349 /* Store the data structures necessary for depth-first search. */
350 struct depth_first_search_dsS {
351 /* stack for backtracking during the algorithm */
354 /* number of edges in the stack. That is, positions 0, ..., sp-1
358 /* record of basic blocks already seen by depth-first search */
359 sbitmap visited_blocks;
361 typedef struct depth_first_search_dsS *depth_first_search_ds;
363 /* Have print_rtl_and_abort give the same information that fancy_abort
365 #define print_rtl_and_abort() \
366 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
368 /* Forward declarations */
369 static bool try_crossjump_to_edge PARAMS ((int, edge, edge));
370 static bool try_crossjump_bb PARAMS ((int, basic_block));
371 static bool outgoing_edges_match PARAMS ((basic_block, basic_block));
372 static int flow_find_cross_jump PARAMS ((int, basic_block, basic_block,
374 static int count_basic_blocks PARAMS ((rtx));
375 static void find_basic_blocks_1 PARAMS ((rtx));
376 static rtx find_label_refs PARAMS ((rtx, rtx));
377 static void make_edges PARAMS ((rtx, int, int, int));
378 static void make_label_edge PARAMS ((sbitmap *, basic_block,
380 static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
382 static void commit_one_edge_insertion PARAMS ((edge));
384 static void delete_unreachable_blocks PARAMS ((void));
385 static int can_delete_note_p PARAMS ((rtx));
386 static void expunge_block PARAMS ((basic_block));
387 static int can_delete_label_p PARAMS ((rtx));
388 static int tail_recursion_label_p PARAMS ((rtx));
389 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
391 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
393 static int merge_blocks PARAMS ((edge,basic_block,basic_block,
395 static bool try_optimize_cfg PARAMS ((int));
396 static bool can_fallthru PARAMS ((basic_block, basic_block));
397 static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block));
398 static bool try_simplify_condjump PARAMS ((basic_block));
399 static bool try_forward_edges PARAMS ((int, basic_block));
400 static void tidy_fallthru_edges PARAMS ((void));
401 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
402 static void verify_wide_reg PARAMS ((int, rtx, rtx));
403 static void verify_local_live_at_start PARAMS ((regset, basic_block));
404 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
405 static void notice_stack_pointer_modification PARAMS ((rtx));
406 static void mark_reg PARAMS ((rtx, void *));
407 static void mark_regs_live_at_end PARAMS ((regset));
408 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
409 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
410 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
411 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
412 static int insn_dead_p PARAMS ((struct propagate_block_info *,
414 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
416 static void mark_set_regs PARAMS ((struct propagate_block_info *,
418 static void mark_set_1 PARAMS ((struct propagate_block_info *,
419 enum rtx_code, rtx, rtx,
421 #ifdef HAVE_conditional_execution
422 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
424 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
425 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
426 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
428 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
429 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
430 static rtx not_reg_cond PARAMS ((rtx));
431 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
434 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
435 rtx, rtx, rtx, rtx, rtx));
436 static void find_auto_inc PARAMS ((struct propagate_block_info *,
438 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
440 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
442 static void mark_used_reg PARAMS ((struct propagate_block_info *,
444 static void mark_used_regs PARAMS ((struct propagate_block_info *,
446 void dump_flow_info PARAMS ((FILE *));
447 void debug_flow_info PARAMS ((void));
448 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
452 static void add_to_mem_set_list PARAMS ((struct propagate_block_info *,
454 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
456 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
458 static void remove_fake_successors PARAMS ((basic_block));
459 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
461 static void flow_edge_list_print PARAMS ((const char *, const edge *,
463 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
465 static int flow_loop_nested_p PARAMS ((struct loop *,
467 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
469 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
470 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
471 static void flow_dfs_compute_reverse_init
472 PARAMS ((depth_first_search_ds));
473 static void flow_dfs_compute_reverse_add_bb
474 PARAMS ((depth_first_search_ds, basic_block));
475 static basic_block flow_dfs_compute_reverse_execute
476 PARAMS ((depth_first_search_ds));
477 static void flow_dfs_compute_reverse_finish
478 PARAMS ((depth_first_search_ds));
479 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
480 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
482 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
483 static void flow_loops_tree_build PARAMS ((struct loops *));
484 static int flow_loop_level_compute PARAMS ((struct loop *, int));
485 static int flow_loops_level_compute PARAMS ((struct loops *));
486 static void delete_dead_jumptables PARAMS ((void));
487 static bool back_edge_of_syntactic_loop_p PARAMS ((basic_block, basic_block));
488 static bool need_fake_edge_p PARAMS ((rtx));
490 /* Find basic blocks of the current function.
491 F is the first insn of the function and NREGS the number of register
495 find_basic_blocks (f, nregs, file)
497 int nregs ATTRIBUTE_UNUSED;
498 FILE *file ATTRIBUTE_UNUSED;
501 timevar_push (TV_CFG);
503 /* Flush out existing data. */
504 if (basic_block_info != NULL)
510 /* Clear bb->aux on all extant basic blocks. We'll use this as a
511 tag for reuse during create_basic_block, just in case some pass
512 copies around basic block notes improperly. */
513 for (i = 0; i < n_basic_blocks; ++i)
514 BASIC_BLOCK (i)->aux = NULL;
516 VARRAY_FREE (basic_block_info);
519 n_basic_blocks = count_basic_blocks (f);
521 /* Size the basic block table. The actual structures will be allocated
522 by find_basic_blocks_1, since we want to keep the structure pointers
523 stable across calls to find_basic_blocks. */
524 /* ??? This whole issue would be much simpler if we called find_basic_blocks
525 exactly once, and thereafter we don't have a single long chain of
526 instructions at all until close to the end of compilation when we
527 actually lay them out. */
529 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
531 find_basic_blocks_1 (f);
533 /* Record the block to which an insn belongs. */
534 /* ??? This should be done another way, by which (perhaps) a label is
535 tagged directly with the basic block that it starts. It is used for
536 more than that currently, but IMO that is the only valid use. */
538 max_uid = get_max_uid ();
540 /* Leave space for insns life_analysis makes in some cases for auto-inc.
541 These cases are rare, so we don't need too much space. */
542 max_uid += max_uid / 10;
545 compute_bb_for_insn (max_uid);
547 /* Discover the edges of our cfg. */
548 make_edges (label_value_list, 0, n_basic_blocks - 1, 0);
550 /* Do very simple cleanup now, for the benefit of code that runs between
551 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
552 tidy_fallthru_edges ();
554 mark_critical_edges ();
556 #ifdef ENABLE_CHECKING
559 timevar_pop (TV_CFG);
563 check_function_return_warnings ()
565 if (warn_missing_noreturn
566 && !TREE_THIS_VOLATILE (cfun->decl)
567 && EXIT_BLOCK_PTR->pred == NULL
568 && (lang_missing_noreturn_ok_p
569 && !lang_missing_noreturn_ok_p (cfun->decl)))
570 warning ("function might be possible candidate for attribute `noreturn'");
572 /* If we have a path to EXIT, then we do return. */
573 if (TREE_THIS_VOLATILE (cfun->decl)
574 && EXIT_BLOCK_PTR->pred != NULL)
575 warning ("`noreturn' function does return");
577 /* If the clobber_return_insn appears in some basic block, then we
578 do reach the end without returning a value. */
579 else if (warn_return_type
580 && cfun->x_clobber_return_insn != NULL
581 && EXIT_BLOCK_PTR->pred != NULL)
583 int max_uid = get_max_uid ();
585 /* If clobber_return_insn was excised by jump1, then renumber_insns
586 can make max_uid smaller than the number still recorded in our rtx.
587 That's fine, since this is a quick way of verifying that the insn
588 is no longer in the chain. */
589 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
591 /* Recompute insn->block mapping, since the initial mapping is
592 set before we delete unreachable blocks. */
593 compute_bb_for_insn (max_uid);
595 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
596 warning ("control reaches end of non-void function");
601 /* Count the basic blocks of the function. */
604 count_basic_blocks (f)
608 register RTX_CODE prev_code;
609 register int count = 0;
610 int saw_abnormal_edge = 0;
612 prev_code = JUMP_INSN;
613 for (insn = f; insn; insn = NEXT_INSN (insn))
615 enum rtx_code code = GET_CODE (insn);
617 if (code == CODE_LABEL
618 || (GET_RTX_CLASS (code) == 'i'
619 && (prev_code == JUMP_INSN
620 || prev_code == BARRIER
621 || saw_abnormal_edge)))
623 saw_abnormal_edge = 0;
627 /* Record whether this insn created an edge. */
628 if (code == CALL_INSN)
632 /* If there is a nonlocal goto label and the specified
633 region number isn't -1, we have an edge. */
634 if (nonlocal_goto_handler_labels
635 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
636 || INTVAL (XEXP (note, 0)) >= 0))
637 saw_abnormal_edge = 1;
639 else if (can_throw_internal (insn))
640 saw_abnormal_edge = 1;
642 else if (flag_non_call_exceptions
644 && can_throw_internal (insn))
645 saw_abnormal_edge = 1;
651 /* The rest of the compiler works a bit smoother when we don't have to
652 check for the edge case of do-nothing functions with no basic blocks. */
655 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
662 /* Scan a list of insns for labels referred to other than by jumps.
663 This is used to scan the alternatives of a call placeholder. */
665 find_label_refs (f, lvl)
671 for (insn = f; insn; insn = NEXT_INSN (insn))
672 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
676 /* Make a list of all labels referred to other than by jumps
677 (which just don't have the REG_LABEL notes).
679 Make a special exception for labels followed by an ADDR*VEC,
680 as this would be a part of the tablejump setup code.
682 Make a special exception to registers loaded with label
683 values just before jump insns that use them. */
685 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
686 if (REG_NOTE_KIND (note) == REG_LABEL)
688 rtx lab = XEXP (note, 0), next;
690 if ((next = next_nonnote_insn (lab)) != NULL
691 && GET_CODE (next) == JUMP_INSN
692 && (GET_CODE (PATTERN (next)) == ADDR_VEC
693 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
695 else if (GET_CODE (lab) == NOTE)
697 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
698 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
701 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
708 /* Assume that someone emitted code with control flow instructions to the
709 basic block. Update the data structure. */
711 find_sub_basic_blocks (bb)
716 rtx jump_insn = NULL_RTX;
718 basic_block first_bb = bb;
724 if (GET_CODE (insn) == CODE_LABEL)
725 insn = NEXT_INSN (insn);
727 /* Scan insn chain and try to find new basic block boundaries. */
730 enum rtx_code code = GET_CODE (insn);
737 /* On code label, split current basic block. */
739 falltru = split_block (bb, PREV_INSN (insn));
743 remove_edge (falltru);
745 if (LABEL_ALTERNATE_NAME (insn))
746 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
750 /* In case we've previously split insn on the JUMP_INSN, move the
751 block header to proper place. */
754 falltru = split_block (bb, PREV_INSN (insn));
757 remove_edge (falltru);
760 /* We need some special care for those expressions. */
761 if (GET_CODE (insn) == JUMP_INSN)
763 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
764 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
774 insn = NEXT_INSN (insn);
777 /* In case expander replaced normal insn by sequence terminating by
778 return and barrier, or possibly other sequence not behaving like
779 ordinary jump, we need to take care and move basic block boundary. */
780 if (jump_insn && GET_CODE (bb->end) != JUMP_INSN)
783 /* We've possibly replaced the conditional jump by conditional jump
784 followed by cleanup at fallthru edge, so the outgoing edges may
786 purge_dead_edges (bb);
788 /* Now re-scan and wire in all edges. This expect simple (conditional)
789 jumps at the end of each new basic blocks. */
790 make_edges (NULL, first_bb->index, bb->index, 1);
792 /* Update branch probabilities. Expect only (un)conditional jumps
793 to be created with only the forward edges. */
794 for (i = first_bb->index; i <= bb->index; i++)
797 basic_block b = BASIC_BLOCK (i);
802 for (e = b->pred; e; e=e->pred_next)
804 b->count += e->count;
805 b->frequency += EDGE_FREQUENCY (e);
808 if (b->succ && b->succ->succ_next && !b->succ->succ_next->succ_next)
810 rtx note = find_reg_note (b->end, REG_BR_PROB, NULL);
815 probability = INTVAL (XEXP (find_reg_note (b->end,
819 e->probability = probability;
820 e->count = ((b->count * probability + REG_BR_PROB_BASE / 2)
822 f = FALLTHRU_EDGE (b);
823 f->probability = REG_BR_PROB_BASE - probability;
824 f->count = b->count - e->count;
826 if (b->succ && !b->succ->succ_next)
829 e->probability = REG_BR_PROB_BASE;
835 /* Find all basic blocks of the function whose first insn is F.
837 Collect and return a list of labels whose addresses are taken. This
838 will be used in make_edges for use with computed gotos. */
841 find_basic_blocks_1 (f)
844 register rtx insn, next;
846 rtx bb_note = NULL_RTX;
852 /* We process the instructions in a slightly different way than we did
853 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
854 closed out the previous block, so that it gets attached at the proper
855 place. Since this form should be equivalent to the previous,
856 count_basic_blocks continues to use the old form as a check. */
858 for (insn = f; insn; insn = next)
860 enum rtx_code code = GET_CODE (insn);
862 next = NEXT_INSN (insn);
868 int kind = NOTE_LINE_NUMBER (insn);
870 /* Look for basic block notes with which to keep the
871 basic_block_info pointers stable. Unthread the note now;
872 we'll put it back at the right place in create_basic_block.
873 Or not at all if we've already found a note in this block. */
874 if (kind == NOTE_INSN_BASIC_BLOCK)
876 if (bb_note == NULL_RTX)
879 next = flow_delete_insn (insn);
885 /* A basic block starts at a label. If we've closed one off due
886 to a barrier or some such, no need to do it again. */
887 if (head != NULL_RTX)
889 create_basic_block (i++, head, end, bb_note);
897 /* A basic block ends at a jump. */
898 if (head == NULL_RTX)
902 /* ??? Make a special check for table jumps. The way this
903 happens is truly and amazingly gross. We are about to
904 create a basic block that contains just a code label and
905 an addr*vec jump insn. Worse, an addr_diff_vec creates
906 its own natural loop.
908 Prevent this bit of brain damage, pasting things together
909 correctly in make_edges.
911 The correct solution involves emitting the table directly
912 on the tablejump instruction as a note, or JUMP_LABEL. */
914 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
915 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
923 goto new_bb_inclusive;
926 /* A basic block ends at a barrier. It may be that an unconditional
927 jump already closed the basic block -- no need to do it again. */
928 if (head == NULL_RTX)
930 goto new_bb_exclusive;
934 /* Record whether this call created an edge. */
935 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
936 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
938 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
940 /* Scan each of the alternatives for label refs. */
941 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
942 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
943 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
944 /* Record its tail recursion label, if any. */
945 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
946 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
949 /* A basic block ends at a call that can either throw or
950 do a non-local goto. */
951 if ((nonlocal_goto_handler_labels && region >= 0)
952 || can_throw_internal (insn))
955 if (head == NULL_RTX)
960 create_basic_block (i++, head, end, bb_note);
961 head = end = NULL_RTX;
969 /* Non-call exceptions generate new blocks just like calls. */
970 if (flag_non_call_exceptions && can_throw_internal (insn))
971 goto new_bb_inclusive;
973 if (head == NULL_RTX)
982 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
986 /* Make a list of all labels referred to other than by jumps.
988 Make a special exception for labels followed by an ADDR*VEC,
989 as this would be a part of the tablejump setup code.
991 Make a special exception to registers loaded with label
992 values just before jump insns that use them. */
994 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
995 if (REG_NOTE_KIND (note) == REG_LABEL)
997 rtx lab = XEXP (note, 0), next;
999 if ((next = next_nonnote_insn (lab)) != NULL
1000 && GET_CODE (next) == JUMP_INSN
1001 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1002 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1004 else if (GET_CODE (lab) == NOTE)
1006 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
1007 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
1010 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
1015 if (head != NULL_RTX)
1016 create_basic_block (i++, head, end, bb_note);
1018 flow_delete_insn (bb_note);
1020 if (i != n_basic_blocks)
1023 label_value_list = lvl;
1024 tail_recursion_label_list = trll;
1027 /* Tidy the CFG by deleting unreachable code and whatnot. */
1033 timevar_push (TV_CLEANUP_CFG);
1034 delete_unreachable_blocks ();
1035 if (try_optimize_cfg (mode))
1036 delete_unreachable_blocks ();
1037 mark_critical_edges ();
1039 /* Kill the data we won't maintain. */
1040 free_EXPR_LIST_list (&label_value_list);
1041 free_EXPR_LIST_list (&tail_recursion_label_list);
1042 timevar_pop (TV_CLEANUP_CFG);
1045 /* Create a new basic block consisting of the instructions between
1046 HEAD and END inclusive. Reuses the note and basic block struct
1047 in BB_NOTE, if any. */
1050 create_basic_block (index, head, end, bb_note)
1052 rtx head, end, bb_note;
1057 && ! RTX_INTEGRATED_P (bb_note)
1058 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1061 /* If we found an existing note, thread it back onto the chain. */
1065 if (GET_CODE (head) == CODE_LABEL)
1069 after = PREV_INSN (head);
1073 if (after != bb_note && NEXT_INSN (after) != bb_note)
1074 reorder_insns (bb_note, bb_note, after);
1078 /* Otherwise we must create a note and a basic block structure.
1079 Since we allow basic block structs in rtl, give the struct
1080 the same lifetime by allocating it off the function obstack
1081 rather than using malloc. */
1083 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1084 memset (bb, 0, sizeof (*bb));
1086 if (GET_CODE (head) == CODE_LABEL)
1087 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1090 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1093 NOTE_BASIC_BLOCK (bb_note) = bb;
1096 /* Always include the bb note in the block. */
1097 if (NEXT_INSN (end) == bb_note)
1103 BASIC_BLOCK (index) = bb;
1105 /* Tag the block so that we know it has been used when considering
1106 other basic block notes. */
1110 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
1111 note associated with the BLOCK. */
1114 first_insn_after_basic_block_note (block)
1119 /* Get the first instruction in the block. */
1122 if (insn == NULL_RTX)
1124 if (GET_CODE (insn) == CODE_LABEL)
1125 insn = NEXT_INSN (insn);
1126 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
1129 return NEXT_INSN (insn);
1132 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1133 indexed by INSN_UID. MAX is the size of the array. */
1136 compute_bb_for_insn (max)
1141 if (basic_block_for_insn)
1142 VARRAY_FREE (basic_block_for_insn);
1143 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1145 for (i = 0; i < n_basic_blocks; ++i)
1147 basic_block bb = BASIC_BLOCK (i);
1154 int uid = INSN_UID (insn);
1156 VARRAY_BB (basic_block_for_insn, uid) = bb;
1159 insn = NEXT_INSN (insn);
1164 /* Free the memory associated with the edge structures. */
1172 for (i = 0; i < n_basic_blocks; ++i)
1174 basic_block bb = BASIC_BLOCK (i);
1176 for (e = bb->succ; e; e = n)
1186 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1192 ENTRY_BLOCK_PTR->succ = 0;
1193 EXIT_BLOCK_PTR->pred = 0;
1198 /* Identify the edges between basic blocks MIN to MAX.
1200 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1201 that are otherwise unreachable may be reachable with a non-local goto.
1203 BB_EH_END is an array indexed by basic block number in which we record
1204 the list of exception regions active at the end of the basic block. */
1207 make_edges (label_value_list, min, max, update_p)
1208 rtx label_value_list;
1209 int min, max, update_p;
1212 sbitmap *edge_cache = NULL;
1214 /* Assume no computed jump; revise as we create edges. */
1215 current_function_has_computed_jump = 0;
1217 /* Heavy use of computed goto in machine-generated code can lead to
1218 nearly fully-connected CFGs. In that case we spend a significant
1219 amount of time searching the edge lists for duplicates. */
1220 if (forced_labels || label_value_list)
1222 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1223 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1226 for (i = min; i <= max; ++i)
1229 for (e = BASIC_BLOCK (i)->succ; e ; e = e->succ_next)
1230 if (e->dest != EXIT_BLOCK_PTR)
1231 SET_BIT (edge_cache[i], e->dest->index);
1235 /* By nature of the way these get numbered, block 0 is always the entry. */
1236 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1238 for (i = min; i <= max; ++i)
1240 basic_block bb = BASIC_BLOCK (i);
1243 int force_fallthru = 0;
1245 if (GET_CODE (bb->head) == CODE_LABEL
1246 && LABEL_ALTERNATE_NAME (bb->head))
1247 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1249 /* Examine the last instruction of the block, and discover the
1250 ways we can leave the block. */
1253 code = GET_CODE (insn);
1256 if (code == JUMP_INSN)
1260 /* Recognize exception handling placeholders. */
1261 if (GET_CODE (PATTERN (insn)) == RESX)
1262 make_eh_edge (edge_cache, bb, insn);
1264 /* Recognize a non-local goto as a branch outside the
1265 current function. */
1266 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1269 /* ??? Recognize a tablejump and do the right thing. */
1270 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1271 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1272 && GET_CODE (tmp) == JUMP_INSN
1273 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1274 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1279 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1280 vec = XVEC (PATTERN (tmp), 0);
1282 vec = XVEC (PATTERN (tmp), 1);
1284 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1285 make_label_edge (edge_cache, bb,
1286 XEXP (RTVEC_ELT (vec, j), 0), 0);
1288 /* Some targets (eg, ARM) emit a conditional jump that also
1289 contains the out-of-range target. Scan for these and
1290 add an edge if necessary. */
1291 if ((tmp = single_set (insn)) != NULL
1292 && SET_DEST (tmp) == pc_rtx
1293 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1294 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1295 make_label_edge (edge_cache, bb,
1296 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1298 #ifdef CASE_DROPS_THROUGH
1299 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1300 us naturally detecting fallthru into the next block. */
1305 /* If this is a computed jump, then mark it as reaching
1306 everything on the label_value_list and forced_labels list. */
1307 else if (computed_jump_p (insn))
1309 current_function_has_computed_jump = 1;
1311 for (x = label_value_list; x; x = XEXP (x, 1))
1312 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1314 for (x = forced_labels; x; x = XEXP (x, 1))
1315 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1318 /* Returns create an exit out. */
1319 else if (returnjump_p (insn))
1320 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1322 /* Otherwise, we have a plain conditional or unconditional jump. */
1325 if (! JUMP_LABEL (insn))
1327 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1331 /* If this is a sibling call insn, then this is in effect a
1332 combined call and return, and so we need an edge to the
1333 exit block. No need to worry about EH edges, since we
1334 wouldn't have created the sibling call in the first place. */
1336 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1337 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1338 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1340 /* If this is a CALL_INSN, then mark it as reaching the active EH
1341 handler for this CALL_INSN. If we're handling non-call
1342 exceptions then any insn can reach any of the active handlers.
1344 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1346 else if (code == CALL_INSN || flag_non_call_exceptions)
1348 /* Add any appropriate EH edges. */
1349 make_eh_edge (edge_cache, bb, insn);
1351 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1353 /* ??? This could be made smarter: in some cases it's possible
1354 to tell that certain calls will not do a nonlocal goto.
1356 For example, if the nested functions that do the nonlocal
1357 gotos do not have their addresses taken, then only calls to
1358 those functions or to other nested functions that use them
1359 could possibly do nonlocal gotos. */
1360 /* We do know that a REG_EH_REGION note with a value less
1361 than 0 is guaranteed not to perform a non-local goto. */
1362 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1363 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1364 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1365 make_label_edge (edge_cache, bb, XEXP (x, 0),
1366 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1370 /* Find out if we can drop through to the next block. */
1371 insn = next_nonnote_insn (insn);
1372 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1373 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1374 else if (i + 1 < n_basic_blocks)
1376 rtx tmp = BLOCK_HEAD (i + 1);
1377 if (GET_CODE (tmp) == NOTE)
1378 tmp = next_nonnote_insn (tmp);
1379 if (force_fallthru || insn == tmp)
1380 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1385 sbitmap_vector_free (edge_cache);
1388 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1389 about the edge that is accumulated between calls. */
1392 make_edge (edge_cache, src, dst, flags)
1393 sbitmap *edge_cache;
1394 basic_block src, dst;
1400 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1401 many edges to them, and we didn't allocate memory for it. */
1402 use_edge_cache = (edge_cache
1403 && src != ENTRY_BLOCK_PTR
1404 && dst != EXIT_BLOCK_PTR);
1406 /* Make sure we don't add duplicate edges. */
1407 switch (use_edge_cache)
1410 /* Quick test for non-existance of the edge. */
1411 if (! TEST_BIT (edge_cache[src->index], dst->index))
1414 /* The edge exists; early exit if no work to do. */
1420 for (e = src->succ; e; e = e->succ_next)
1429 e = (edge) xcalloc (1, sizeof (*e));
1432 e->succ_next = src->succ;
1433 e->pred_next = dst->pred;
1442 SET_BIT (edge_cache[src->index], dst->index);
1445 /* Create an edge from a basic block to a label. */
1448 make_label_edge (edge_cache, src, label, flags)
1449 sbitmap *edge_cache;
1454 if (GET_CODE (label) != CODE_LABEL)
1457 /* If the label was never emitted, this insn is junk, but avoid a
1458 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1459 as a result of a syntax error and a diagnostic has already been
1462 if (INSN_UID (label) == 0)
1465 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1468 /* Create the edges generated by INSN in REGION. */
1471 make_eh_edge (edge_cache, src, insn)
1472 sbitmap *edge_cache;
1476 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1479 handlers = reachable_handlers (insn);
1481 for (i = handlers; i; i = XEXP (i, 1))
1482 make_label_edge (edge_cache, src, XEXP (i, 0),
1483 EDGE_ABNORMAL | EDGE_EH | is_call);
1485 free_INSN_LIST_list (&handlers);
1488 /* Identify critical edges and set the bits appropriately. */
1491 mark_critical_edges ()
1493 int i, n = n_basic_blocks;
1496 /* We begin with the entry block. This is not terribly important now,
1497 but could be if a front end (Fortran) implemented alternate entry
1499 bb = ENTRY_BLOCK_PTR;
1506 /* (1) Critical edges must have a source with multiple successors. */
1507 if (bb->succ && bb->succ->succ_next)
1509 for (e = bb->succ; e; e = e->succ_next)
1511 /* (2) Critical edges must have a destination with multiple
1512 predecessors. Note that we know there is at least one
1513 predecessor -- the edge we followed to get here. */
1514 if (e->dest->pred->pred_next)
1515 e->flags |= EDGE_CRITICAL;
1517 e->flags &= ~EDGE_CRITICAL;
1522 for (e = bb->succ; e; e = e->succ_next)
1523 e->flags &= ~EDGE_CRITICAL;
1528 bb = BASIC_BLOCK (i);
1532 /* Mark the back edges in DFS traversal.
1533 Return non-zero if a loop (natural or otherwise) is present.
1534 Inspired by Depth_First_Search_PP described in:
1536 Advanced Compiler Design and Implementation
1538 Morgan Kaufmann, 1997
1540 and heavily borrowed from flow_depth_first_order_compute. */
1543 mark_dfs_back_edges ()
1554 /* Allocate the preorder and postorder number arrays. */
1555 pre = (int *) xcalloc (n_basic_blocks, sizeof (int));
1556 post = (int *) xcalloc (n_basic_blocks, sizeof (int));
1558 /* Allocate stack for back-tracking up CFG. */
1559 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
1562 /* Allocate bitmap to track nodes that have been visited. */
1563 visited = sbitmap_alloc (n_basic_blocks);
1565 /* None of the nodes in the CFG have been visited yet. */
1566 sbitmap_zero (visited);
1568 /* Push the first edge on to the stack. */
1569 stack[sp++] = ENTRY_BLOCK_PTR->succ;
1577 /* Look at the edge on the top of the stack. */
1581 e->flags &= ~EDGE_DFS_BACK;
1583 /* Check if the edge destination has been visited yet. */
1584 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
1586 /* Mark that we have visited the destination. */
1587 SET_BIT (visited, dest->index);
1589 pre[dest->index] = prenum++;
1593 /* Since the DEST node has been visited for the first
1594 time, check its successors. */
1595 stack[sp++] = dest->succ;
1598 post[dest->index] = postnum++;
1602 if (dest != EXIT_BLOCK_PTR && src != ENTRY_BLOCK_PTR
1603 && pre[src->index] >= pre[dest->index]
1604 && post[dest->index] == 0)
1605 e->flags |= EDGE_DFS_BACK, found = true;
1607 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
1608 post[src->index] = postnum++;
1611 stack[sp - 1] = e->succ_next;
1620 sbitmap_free (visited);
1625 /* Split a block BB after insn INSN creating a new fallthru edge.
1626 Return the new edge. Note that to keep other parts of the compiler happy,
1627 this function renumbers all the basic blocks so that the new
1628 one has a number one greater than the block split. */
1631 split_block (bb, insn)
1641 /* There is no point splitting the block after its end. */
1642 if (bb->end == insn)
1645 /* Create the new structures. */
1646 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1647 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1650 memset (new_bb, 0, sizeof (*new_bb));
1652 new_bb->head = NEXT_INSN (insn);
1653 new_bb->end = bb->end;
1656 new_bb->succ = bb->succ;
1657 bb->succ = new_edge;
1658 new_bb->pred = new_edge;
1659 new_bb->count = bb->count;
1660 new_bb->frequency = bb->frequency;
1661 new_bb->loop_depth = bb->loop_depth;
1664 new_edge->dest = new_bb;
1665 new_edge->flags = EDGE_FALLTHRU;
1666 new_edge->probability = REG_BR_PROB_BASE;
1667 new_edge->count = bb->count;
1669 /* Redirect the src of the successor edges of bb to point to new_bb. */
1670 for (e = new_bb->succ; e; e = e->succ_next)
1673 /* Place the new block just after the block being split. */
1674 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1676 /* Some parts of the compiler expect blocks to be number in
1677 sequential order so insert the new block immediately after the
1678 block being split.. */
1680 for (i = n_basic_blocks - 1; i > j + 1; --i)
1682 basic_block tmp = BASIC_BLOCK (i - 1);
1683 BASIC_BLOCK (i) = tmp;
1687 BASIC_BLOCK (i) = new_bb;
1690 if (GET_CODE (new_bb->head) == CODE_LABEL)
1692 /* Create the basic block note. */
1693 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1695 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1697 /* If the only thing in this new block was the label, make sure
1698 the block note gets included. */
1699 if (new_bb->head == new_bb->end)
1700 new_bb->end = bb_note;
1704 /* Create the basic block note. */
1705 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1707 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1708 new_bb->head = bb_note;
1711 update_bb_for_insn (new_bb);
1713 if (bb->global_live_at_start)
1715 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1716 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1717 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1719 /* We now have to calculate which registers are live at the end
1720 of the split basic block and at the start of the new basic
1721 block. Start with those registers that are known to be live
1722 at the end of the original basic block and get
1723 propagate_block to determine which registers are live. */
1724 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1725 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1726 COPY_REG_SET (bb->global_live_at_end,
1727 new_bb->global_live_at_start);
1733 /* Return label in the head of basic block. Create one if it doesn't exist. */
1738 if (block == EXIT_BLOCK_PTR)
1740 if (GET_CODE (block->head) != CODE_LABEL)
1742 block->head = emit_label_before (gen_label_rtx (), block->head);
1743 if (basic_block_for_insn)
1744 set_block_for_insn (block->head, block);
1749 /* Return true if the block has no effect and only forwards control flow to
1750 its single destination. */
1752 forwarder_block_p (bb)
1755 rtx insn = bb->head;
1756 if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
1757 || !bb->succ || bb->succ->succ_next)
1760 while (insn != bb->end)
1762 if (active_insn_p (insn))
1764 insn = NEXT_INSN (insn);
1766 return (!active_insn_p (insn)
1767 || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)));
1770 /* Return nonzero if we can reach target from src by falling trought. */
1772 can_fallthru (src, target)
1773 basic_block src, target;
1775 rtx insn = src->end;
1776 rtx insn2 = target->head;
1778 if (src->index + 1 == target->index && !active_insn_p (insn2))
1779 insn2 = next_active_insn (insn2);
1780 /* ??? Later we may add code to move jump tables offline. */
1781 return next_active_insn (insn) == insn2;
1784 /* Attempt to perform edge redirection by replacing possibly complex jump
1785 instruction by unconditional jump or removing jump completely.
1786 This can apply only if all edges now point to the same block.
1788 The parameters and return values are equivalent to redirect_edge_and_branch.
1791 try_redirect_by_replacing_jump (e, target)
1795 basic_block src = e->src;
1796 rtx insn = src->end, kill_from;
1801 /* Verify that all targets will be TARGET. */
1802 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
1803 if (tmp->dest != target && tmp != e)
1805 if (tmp || !onlyjump_p (insn))
1808 /* Avoid removing branch with side effects. */
1809 set = single_set (insn);
1810 if (!set || side_effects_p (set))
1813 /* In case we zap a conditional jump, we'll need to kill
1814 the cc0 setter too. */
1817 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
1818 kill_from = PREV_INSN (insn);
1821 /* See if we can create the fallthru edge. */
1822 if (can_fallthru (src, target))
1824 src->end = PREV_INSN (kill_from);
1826 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
1829 /* Selectivly unlink whole insn chain. */
1830 flow_delete_insn_chain (kill_from, PREV_INSN (target->head));
1832 /* If this already is simplejump, redirect it. */
1833 else if (simplejump_p (insn))
1835 if (e->dest == target)
1838 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
1839 INSN_UID (insn), e->dest->index, target->index);
1840 redirect_jump (insn, block_label (target), 0);
1842 /* Or replace possibly complicated jump insn by simple jump insn. */
1845 rtx target_label = block_label (target);
1848 src->end = emit_jump_insn_before (gen_jump (target_label), kill_from);
1849 JUMP_LABEL (src->end) = target_label;
1850 LABEL_NUSES (target_label)++;
1851 if (basic_block_for_insn)
1852 set_block_for_new_insns (src->end, src);
1854 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
1855 INSN_UID (insn), INSN_UID (src->end));
1857 flow_delete_insn_chain (kill_from, insn);
1859 barrier = next_nonnote_insn (src->end);
1860 if (!barrier || GET_CODE (barrier) != BARRIER)
1861 emit_barrier_after (src->end);
1864 /* Keep only one edge out and set proper flags. */
1865 while (src->succ->succ_next)
1866 remove_edge (src->succ);
1869 e->flags = EDGE_FALLTHRU;
1872 e->probability = REG_BR_PROB_BASE;
1873 e->count = src->count;
1875 /* We don't want a block to end on a line-number note since that has
1876 the potential of changing the code between -g and not -g. */
1877 while (GET_CODE (e->src->end) == NOTE
1878 && NOTE_LINE_NUMBER (e->src->end) >= 0)
1880 rtx prev = PREV_INSN (e->src->end);
1881 flow_delete_insn (e->src->end);
1885 if (e->dest != target)
1886 redirect_edge_succ (e, target);
1890 /* Return last loop_beg note appearing after INSN, before start of next
1891 basic block. Return INSN if there are no such notes.
1893 When emmiting jump to redirect an fallthru edge, it should always
1894 appear after the LOOP_BEG notes, as loop optimizer expect loop to
1895 eighter start by fallthru edge or jump following the LOOP_BEG note
1896 jumping to the loop exit test. */
1898 last_loop_beg_note (insn)
1902 insn = NEXT_INSN (insn);
1903 while (GET_CODE (insn) == NOTE
1904 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK)
1906 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1908 insn = NEXT_INSN (insn);
1913 /* Attempt to change code to redirect edge E to TARGET.
1914 Don't do that on expense of adding new instructions or reordering
1917 Function can be also called with edge destionation equivalent to the
1918 TARGET. Then it should try the simplifications and do nothing if
1921 Return true if transformation suceeded. We still return flase in case
1922 E already destinated TARGET and we didn't managed to simplify instruction
1925 redirect_edge_and_branch (e, target)
1930 rtx old_label = e->dest->head;
1931 basic_block src = e->src;
1932 rtx insn = src->end;
1934 if (e->flags & EDGE_COMPLEX)
1937 if (try_redirect_by_replacing_jump (e, target))
1939 /* Do this fast path late, as we want above code to simplify for cases
1940 where called on single edge leaving basic block containing nontrivial
1942 else if (e->dest == target)
1945 /* We can only redirect non-fallthru edges of jump insn. */
1946 if (e->flags & EDGE_FALLTHRU)
1948 if (GET_CODE (insn) != JUMP_INSN)
1951 /* Recognize a tablejump and adjust all matching cases. */
1952 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1953 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1954 && GET_CODE (tmp) == JUMP_INSN
1955 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1956 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1960 rtx new_label = block_label (target);
1962 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1963 vec = XVEC (PATTERN (tmp), 0);
1965 vec = XVEC (PATTERN (tmp), 1);
1967 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1968 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1970 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
1971 --LABEL_NUSES (old_label);
1972 ++LABEL_NUSES (new_label);
1975 /* Handle casesi dispatch insns */
1976 if ((tmp = single_set (insn)) != NULL
1977 && SET_DEST (tmp) == pc_rtx
1978 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1979 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1980 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1982 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1984 --LABEL_NUSES (old_label);
1985 ++LABEL_NUSES (new_label);
1990 /* ?? We may play the games with moving the named labels from
1991 one basic block to the other in case only one computed_jump is
1993 if (computed_jump_p (insn))
1996 /* A return instruction can't be redirected. */
1997 if (returnjump_p (insn))
2000 /* If the insn doesn't go where we think, we're confused. */
2001 if (JUMP_LABEL (insn) != old_label)
2003 redirect_jump (insn, block_label (target), 0);
2007 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
2008 e->src->index, e->dest->index, target->index);
2009 if (e->dest != target)
2010 redirect_edge_succ_nodup (e, target);
2014 /* Redirect edge even at the expense of creating new jump insn or
2015 basic block. Return new basic block if created, NULL otherwise.
2016 Abort if converison is impossible. */
2018 redirect_edge_and_branch_force (e, target)
2028 if (redirect_edge_and_branch (e, target))
2030 if (e->dest == target)
2032 if (e->flags & EDGE_ABNORMAL)
2034 if (!(e->flags & EDGE_FALLTHRU))
2037 e->flags &= ~EDGE_FALLTHRU;
2038 label = block_label (target);
2039 /* Case of the fallthru block. */
2040 if (!e->src->succ->succ_next)
2042 e->src->end = emit_jump_insn_after (gen_jump (label),
2043 last_loop_beg_note (e->src->end));
2044 JUMP_LABEL (e->src->end) = label;
2045 LABEL_NUSES (label)++;
2046 if (basic_block_for_insn)
2047 set_block_for_new_insns (e->src->end, e->src);
2048 emit_barrier_after (e->src->end);
2050 fprintf (rtl_dump_file,
2051 "Emitting jump insn %i to redirect edge %i->%i to %i\n",
2052 INSN_UID (e->src->end), e->src->index, e->dest->index,
2054 redirect_edge_succ (e, target);
2057 /* Redirecting fallthru edge of the conditional needs extra work. */
2060 fprintf (rtl_dump_file,
2061 "Emitting jump insn %i in new BB to redirect edge %i->%i to %i\n",
2062 INSN_UID (e->src->end), e->src->index, e->dest->index,
2065 /* Create the new structures. */
2066 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
2067 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
2070 memset (new_bb, 0, sizeof (*new_bb));
2072 new_bb->end = new_bb->head = last_loop_beg_note (e->src->end);
2073 new_bb->succ = NULL;
2074 new_bb->pred = new_edge;
2075 new_bb->count = e->count;
2076 new_bb->frequency = EDGE_FREQUENCY (e);
2077 new_bb->loop_depth = e->dest->loop_depth;
2079 new_edge->flags = EDGE_FALLTHRU;
2080 new_edge->probability = e->probability;
2081 new_edge->count = e->count;
2083 if (target->global_live_at_start)
2085 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2086 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2087 COPY_REG_SET (new_bb->global_live_at_start,
2088 target->global_live_at_start);
2089 COPY_REG_SET (new_bb->global_live_at_end, new_bb->global_live_at_start);
2093 new_edge->src = e->src;
2094 new_edge->dest = new_bb;
2095 new_edge->succ_next = e->src->succ;
2096 e->src->succ = new_edge;
2097 new_edge->pred_next = NULL;
2099 /* Redirect old edge. */
2100 redirect_edge_succ (e, target);
2101 redirect_edge_pred (e, new_bb);
2102 e->probability = REG_BR_PROB_BASE;
2104 /* Place the new block just after the block being split. */
2105 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2107 /* Some parts of the compiler expect blocks to be number in
2108 sequential order so insert the new block immediately after the
2109 block being split.. */
2110 j = new_edge->src->index;
2111 for (i = n_basic_blocks - 1; i > j + 1; --i)
2113 basic_block tmp = BASIC_BLOCK (i - 1);
2114 BASIC_BLOCK (i) = tmp;
2118 BASIC_BLOCK (i) = new_bb;
2121 /* Create the basic block note. */
2122 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, new_bb->head);
2123 NOTE_BASIC_BLOCK (bb_note) = new_bb;
2124 new_bb->head = bb_note;
2126 new_bb->end = emit_jump_insn_after (gen_jump (label), new_bb->head);
2127 JUMP_LABEL (new_bb->end) = label;
2128 LABEL_NUSES (label)++;
2129 if (basic_block_for_insn)
2130 set_block_for_new_insns (new_bb->end, new_bb);
2131 emit_barrier_after (new_bb->end);
2135 /* Helper function for split_edge. Return true in case edge BB2 to BB1
2136 is back edge of syntactic loop. */
2138 back_edge_of_syntactic_loop_p (bb1, bb2)
2139 basic_block bb1, bb2;
2143 if (bb1->index > bb2->index)
2145 if (bb1->index == bb2->index)
2147 for (insn = bb1->end; insn != bb2->head && count >= 0;
2148 insn = NEXT_INSN (insn))
2149 if (GET_CODE (insn) == NOTE)
2151 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
2153 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
2159 /* Split a (typically critical) edge. Return the new block.
2160 Abort on abnormal edges.
2162 ??? The code generally expects to be called on critical edges.
2163 The case of a block ending in an unconditional jump to a
2164 block with multiple predecessors is not handled optimally. */
2167 split_edge (edge_in)
2170 basic_block old_pred, bb, old_succ;
2175 /* Abnormal edges cannot be split. */
2176 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
2179 old_pred = edge_in->src;
2180 old_succ = edge_in->dest;
2182 /* Create the new structures. */
2183 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
2184 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
2187 memset (bb, 0, sizeof (*bb));
2189 /* ??? This info is likely going to be out of date very soon. */
2190 if (old_succ->global_live_at_start)
2192 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2193 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2194 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
2195 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
2199 bb->succ = edge_out;
2200 bb->count = edge_in->count;
2201 bb->frequency = EDGE_FREQUENCY (edge_in);
2203 edge_in->flags &= ~EDGE_CRITICAL;
2205 edge_out->pred_next = old_succ->pred;
2206 edge_out->succ_next = NULL;
2208 edge_out->dest = old_succ;
2209 edge_out->flags = EDGE_FALLTHRU;
2210 edge_out->probability = REG_BR_PROB_BASE;
2211 edge_out->count = edge_in->count;
2213 old_succ->pred = edge_out;
2215 /* Tricky case -- if there existed a fallthru into the successor
2216 (and we're not it) we must add a new unconditional jump around
2217 the new block we're actually interested in.
2219 Further, if that edge is critical, this means a second new basic
2220 block must be created to hold it. In order to simplify correct
2221 insn placement, do this before we touch the existing basic block
2222 ordering for the block we were really wanting. */
2223 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2226 for (e = edge_out->pred_next; e; e = e->pred_next)
2227 if (e->flags & EDGE_FALLTHRU)
2232 basic_block jump_block;
2235 if ((e->flags & EDGE_CRITICAL) == 0
2236 && e->src != ENTRY_BLOCK_PTR)
2238 /* Non critical -- we can simply add a jump to the end
2239 of the existing predecessor. */
2240 jump_block = e->src;
2244 /* We need a new block to hold the jump. The simplest
2245 way to do the bulk of the work here is to recursively
2247 jump_block = split_edge (e);
2248 e = jump_block->succ;
2251 /* Now add the jump insn ... */
2252 pos = emit_jump_insn_after (gen_jump (old_succ->head),
2253 last_loop_beg_note (jump_block->end));
2254 jump_block->end = pos;
2255 if (basic_block_for_insn)
2256 set_block_for_new_insns (pos, jump_block);
2257 emit_barrier_after (pos);
2259 /* ... let jump know that label is in use, ... */
2260 JUMP_LABEL (pos) = old_succ->head;
2261 ++LABEL_NUSES (old_succ->head);
2263 /* ... and clear fallthru on the outgoing edge. */
2264 e->flags &= ~EDGE_FALLTHRU;
2266 /* Continue splitting the interesting edge. */
2270 /* Place the new block just in front of the successor. */
2271 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2272 if (old_succ == EXIT_BLOCK_PTR)
2273 j = n_basic_blocks - 1;
2275 j = old_succ->index;
2276 for (i = n_basic_blocks - 1; i > j; --i)
2278 basic_block tmp = BASIC_BLOCK (i - 1);
2279 BASIC_BLOCK (i) = tmp;
2282 BASIC_BLOCK (i) = bb;
2285 /* Create the basic block note.
2287 Where we place the note can have a noticable impact on the generated
2288 code. Consider this cfg:
2298 If we need to insert an insn on the edge from block 0 to block 1,
2299 we want to ensure the instructions we insert are outside of any
2300 loop notes that physically sit between block 0 and block 1. Otherwise
2301 we confuse the loop optimizer into thinking the loop is a phony. */
2302 if (old_succ != EXIT_BLOCK_PTR
2303 && PREV_INSN (old_succ->head)
2304 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
2305 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG
2306 && !back_edge_of_syntactic_loop_p (old_succ, old_pred))
2307 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
2308 PREV_INSN (old_succ->head));
2309 else if (old_succ != EXIT_BLOCK_PTR)
2310 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
2312 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
2313 NOTE_BASIC_BLOCK (bb_note) = bb;
2314 bb->head = bb->end = bb_note;
2316 /* For non-fallthry edges, we must adjust the predecessor's
2317 jump instruction to target our new block. */
2318 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2320 if (!redirect_edge_and_branch (edge_in, bb))
2324 redirect_edge_succ (edge_in, bb);
2329 /* Queue instructions for insertion on an edge between two basic blocks.
2330 The new instructions and basic blocks (if any) will not appear in the
2331 CFG until commit_edge_insertions is called. */
2334 insert_insn_on_edge (pattern, e)
2338 /* We cannot insert instructions on an abnormal critical edge.
2339 It will be easier to find the culprit if we die now. */
2340 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
2341 == (EDGE_ABNORMAL|EDGE_CRITICAL))
2344 if (e->insns == NULL_RTX)
2347 push_to_sequence (e->insns);
2349 emit_insn (pattern);
2351 e->insns = get_insns ();
2355 /* Update the CFG for the instructions queued on edge E. */
2358 commit_one_edge_insertion (e)
2361 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
2364 /* Pull the insns off the edge now since the edge might go away. */
2366 e->insns = NULL_RTX;
2368 /* Figure out where to put these things. If the destination has
2369 one predecessor, insert there. Except for the exit block. */
2370 if (e->dest->pred->pred_next == NULL
2371 && e->dest != EXIT_BLOCK_PTR)
2375 /* Get the location correct wrt a code label, and "nice" wrt
2376 a basic block note, and before everything else. */
2378 if (GET_CODE (tmp) == CODE_LABEL)
2379 tmp = NEXT_INSN (tmp);
2380 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
2381 tmp = NEXT_INSN (tmp);
2382 if (tmp == bb->head)
2385 after = PREV_INSN (tmp);
2388 /* If the source has one successor and the edge is not abnormal,
2389 insert there. Except for the entry block. */
2390 else if ((e->flags & EDGE_ABNORMAL) == 0
2391 && e->src->succ->succ_next == NULL
2392 && e->src != ENTRY_BLOCK_PTR)
2395 /* It is possible to have a non-simple jump here. Consider a target
2396 where some forms of unconditional jumps clobber a register. This
2397 happens on the fr30 for example.
2399 We know this block has a single successor, so we can just emit
2400 the queued insns before the jump. */
2401 if (GET_CODE (bb->end) == JUMP_INSN)
2407 /* We'd better be fallthru, or we've lost track of what's what. */
2408 if ((e->flags & EDGE_FALLTHRU) == 0)
2415 /* Otherwise we must split the edge. */
2418 bb = split_edge (e);
2422 /* Now that we've found the spot, do the insertion. */
2424 /* Set the new block number for these insns, if structure is allocated. */
2425 if (basic_block_for_insn)
2428 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
2429 set_block_for_insn (i, bb);
2434 emit_insns_before (insns, before);
2435 if (before == bb->head)
2438 last = prev_nonnote_insn (before);
2442 last = emit_insns_after (insns, after);
2443 if (after == bb->end)
2447 if (returnjump_p (last))
2449 /* ??? Remove all outgoing edges from BB and add one for EXIT.
2450 This is not currently a problem because this only happens
2451 for the (single) epilogue, which already has a fallthru edge
2455 if (e->dest != EXIT_BLOCK_PTR
2456 || e->succ_next != NULL
2457 || (e->flags & EDGE_FALLTHRU) == 0)
2459 e->flags &= ~EDGE_FALLTHRU;
2461 emit_barrier_after (last);
2465 flow_delete_insn (before);
2467 else if (GET_CODE (last) == JUMP_INSN)
2469 find_sub_basic_blocks (bb);
2472 /* Update the CFG for all queued instructions. */
2475 commit_edge_insertions ()
2479 compute_bb_for_insn (get_max_uid ());
2481 #ifdef ENABLE_CHECKING
2482 verify_flow_info ();
2486 bb = ENTRY_BLOCK_PTR;
2491 for (e = bb->succ; e; e = next)
2493 next = e->succ_next;
2495 commit_one_edge_insertion (e);
2498 if (++i >= n_basic_blocks)
2500 bb = BASIC_BLOCK (i);
2504 /* Return true if we need to add fake edge to exit.
2505 Helper function for the flow_call_edges_add. */
2507 need_fake_edge_p (insn)
2513 if ((GET_CODE (insn) == CALL_INSN
2514 && !SIBLING_CALL_P (insn)
2515 && !find_reg_note (insn, REG_NORETURN, NULL)
2516 && !CONST_OR_PURE_CALL_P (insn)))
2519 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2520 && MEM_VOLATILE_P (PATTERN (insn)))
2521 || (GET_CODE (PATTERN (insn)) == PARALLEL
2522 && asm_noperands (insn) != -1
2523 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2524 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2527 /* Add fake edges to the function exit for any non constant and non noreturn
2528 calls, volatile inline assembly in the bitmap of blocks specified by
2529 BLOCKS or to the whole CFG if BLOCKS is zero. Return the nuber of blocks
2532 The goal is to expose cases in which entering a basic block does not imply
2533 that all subsequent instructions must be executed. */
2536 flow_call_edges_add (blocks)
2540 int blocks_split = 0;
2543 bool check_last_block = false;
2545 /* Map bb indicies into basic block pointers since split_block
2546 will renumber the basic blocks. */
2548 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2552 for (i = 0; i < n_basic_blocks; i++)
2553 bbs[bb_num++] = BASIC_BLOCK (i);
2554 check_last_block = true;
2558 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2560 bbs[bb_num++] = BASIC_BLOCK (i);
2561 if (i == n_basic_blocks - 1)
2562 check_last_block = true;
2566 /* In the last basic block, before epilogue generation, there will be
2567 a fallthru edge to EXIT. Special care is required if the last insn
2568 of the last basic block is a call because make_edge folds duplicate
2569 edges, which would result in the fallthru edge also being marked
2570 fake, which would result in the fallthru edge being removed by
2571 remove_fake_edges, which would result in an invalid CFG.
2573 Moreover, we can't elide the outgoing fake edge, since the block
2574 profiler needs to take this into account in order to solve the minimal
2575 spanning tree in the case that the call doesn't return.
2577 Handle this by adding a dummy instruction in a new last basic block. */
2578 if (check_last_block
2579 && need_fake_edge_p (BASIC_BLOCK (n_basic_blocks - 1)->end))
2582 for (e = BASIC_BLOCK (n_basic_blocks - 1)->succ; e; e = e->succ_next)
2583 if (e->dest == EXIT_BLOCK_PTR)
2585 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2586 commit_edge_insertions ();
2590 /* Now add fake edges to the function exit for any non constant
2591 calls since there is no way that we can determine if they will
2594 for (i = 0; i < bb_num; i++)
2596 basic_block bb = bbs[i];
2600 for (insn = bb->end; ; insn = prev_insn)
2602 prev_insn = PREV_INSN (insn);
2603 if (need_fake_edge_p (insn))
2607 /* The above condition should be enought to verify that there is
2608 no edge to the exit block in CFG already. Calling make_edge in
2609 such case would make us to mark that edge as fake and remove it
2611 #ifdef ENABLE_CHECKING
2612 if (insn == bb->end)
2613 for (e = bb->succ; e; e = e->succ_next)
2614 if (e->dest == EXIT_BLOCK_PTR)
2618 /* Note that the following may create a new basic block
2619 and renumber the existing basic blocks. */
2620 e = split_block (bb, insn);
2624 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2626 if (insn == bb->head)
2632 verify_flow_info ();
2635 return blocks_split;
2638 /* Find unreachable blocks. An unreachable block will have NULL in
2639 block->aux, a non-NULL value indicates the block is reachable. */
2642 find_unreachable_blocks ()
2646 basic_block *tos, *worklist;
2649 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2651 /* Use basic_block->aux as a marker. Clear them all. */
2653 for (i = 0; i < n; ++i)
2654 BASIC_BLOCK (i)->aux = NULL;
2656 /* Add our starting points to the worklist. Almost always there will
2657 be only one. It isn't inconcievable that we might one day directly
2658 support Fortran alternate entry points. */
2660 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2664 /* Mark the block with a handy non-null value. */
2668 /* Iterate: find everything reachable from what we've already seen. */
2670 while (tos != worklist)
2672 basic_block b = *--tos;
2674 for (e = b->succ; e; e = e->succ_next)
2685 /* Delete all unreachable basic blocks. */
2687 delete_unreachable_blocks ()
2691 find_unreachable_blocks ();
2693 /* Delete all unreachable basic blocks. Count down so that we
2694 don't interfere with the block renumbering that happens in
2695 flow_delete_block. */
2697 for (i = n_basic_blocks - 1; i >= 0; --i)
2699 basic_block b = BASIC_BLOCK (i);
2702 /* This block was found. Tidy up the mark. */
2705 flow_delete_block (b);
2708 tidy_fallthru_edges ();
2711 /* Return true if NOTE is not one of the ones that must be kept paired,
2712 so that we may simply delete them. */
2715 can_delete_note_p (note)
2718 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2719 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2722 /* Unlink a chain of insns between START and FINISH, leaving notes
2723 that must be paired. */
2726 flow_delete_insn_chain (start, finish)
2729 /* Unchain the insns one by one. It would be quicker to delete all
2730 of these with a single unchaining, rather than one at a time, but
2731 we need to keep the NOTE's. */
2737 next = NEXT_INSN (start);
2738 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2740 else if (GET_CODE (start) == CODE_LABEL
2741 && ! can_delete_label_p (start))
2743 const char *name = LABEL_NAME (start);
2744 PUT_CODE (start, NOTE);
2745 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2746 NOTE_SOURCE_FILE (start) = name;
2749 next = flow_delete_insn (start);
2751 if (start == finish)
2757 /* Delete the insns in a (non-live) block. We physically delete every
2758 non-deleted-note insn, and update the flow graph appropriately.
2760 Return nonzero if we deleted an exception handler. */
2762 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2763 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2766 flow_delete_block (b)
2769 int deleted_handler = 0;
2772 /* If the head of this block is a CODE_LABEL, then it might be the
2773 label for an exception handler which can't be reached.
2775 We need to remove the label from the exception_handler_label list
2776 and remove the associated NOTE_INSN_EH_REGION_BEG and
2777 NOTE_INSN_EH_REGION_END notes. */
2781 never_reached_warning (insn);
2783 if (GET_CODE (insn) == CODE_LABEL)
2784 maybe_remove_eh_handler (insn);
2786 /* Include any jump table following the basic block. */
2788 if (GET_CODE (end) == JUMP_INSN
2789 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2790 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2791 && GET_CODE (tmp) == JUMP_INSN
2792 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2793 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2796 /* Include any barrier that may follow the basic block. */
2797 tmp = next_nonnote_insn (end);
2798 if (tmp && GET_CODE (tmp) == BARRIER)
2801 /* Selectively delete the entire chain. */
2802 flow_delete_insn_chain (insn, end);
2804 /* Remove the edges into and out of this block. Note that there may
2805 indeed be edges in, if we are removing an unreachable loop. */
2809 for (e = b->pred; e; e = next)
2811 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2814 next = e->pred_next;
2818 for (e = b->succ; e; e = next)
2820 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2823 next = e->succ_next;
2832 /* Remove the basic block from the array, and compact behind it. */
2835 return deleted_handler;
2838 /* Remove block B from the basic block array and compact behind it. */
2844 int i, n = n_basic_blocks;
2846 for (i = b->index; i + 1 < n; ++i)
2848 basic_block x = BASIC_BLOCK (i + 1);
2849 BASIC_BLOCK (i) = x;
2853 basic_block_info->num_elements--;
2857 /* Delete INSN by patching it out. Return the next insn. */
2860 flow_delete_insn (insn)
2863 rtx prev = PREV_INSN (insn);
2864 rtx next = NEXT_INSN (insn);
2867 PREV_INSN (insn) = NULL_RTX;
2868 NEXT_INSN (insn) = NULL_RTX;
2869 INSN_DELETED_P (insn) = 1;
2872 NEXT_INSN (prev) = next;
2874 PREV_INSN (next) = prev;
2876 set_last_insn (prev);
2878 if (GET_CODE (insn) == CODE_LABEL)
2879 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2881 /* If deleting a jump, decrement the use count of the label. Deleting
2882 the label itself should happen in the normal course of block merging. */
2883 if (GET_CODE (insn) == JUMP_INSN
2884 && JUMP_LABEL (insn)
2885 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2886 LABEL_NUSES (JUMP_LABEL (insn))--;
2888 /* Also if deleting an insn that references a label. */
2889 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2890 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2891 LABEL_NUSES (XEXP (note, 0))--;
2893 if (GET_CODE (insn) == JUMP_INSN
2894 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2895 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2897 rtx pat = PATTERN (insn);
2898 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
2899 int len = XVECLEN (pat, diff_vec_p);
2902 for (i = 0; i < len; i++)
2903 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
2909 /* True if a given label can be deleted. */
2912 can_delete_label_p (label)
2917 if (LABEL_PRESERVE_P (label))
2920 for (x = forced_labels; x; x = XEXP (x, 1))
2921 if (label == XEXP (x, 0))
2923 for (x = label_value_list; x; x = XEXP (x, 1))
2924 if (label == XEXP (x, 0))
2926 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2927 if (label == XEXP (x, 0))
2930 /* User declared labels must be preserved. */
2931 if (LABEL_NAME (label) != 0)
2938 tail_recursion_label_p (label)
2943 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2944 if (label == XEXP (x, 0))
2950 /* Blocks A and B are to be merged into a single block A. The insns
2951 are already contiguous, hence `nomove'. */
2954 merge_blocks_nomove (a, b)
2958 rtx b_head, b_end, a_end;
2959 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2962 /* If there was a CODE_LABEL beginning B, delete it. */
2965 if (GET_CODE (b_head) == CODE_LABEL)
2967 /* Detect basic blocks with nothing but a label. This can happen
2968 in particular at the end of a function. */
2969 if (b_head == b_end)
2971 del_first = del_last = b_head;
2972 b_head = NEXT_INSN (b_head);
2975 /* Delete the basic block note. */
2976 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2978 if (b_head == b_end)
2983 b_head = NEXT_INSN (b_head);
2986 /* If there was a jump out of A, delete it. */
2988 if (GET_CODE (a_end) == JUMP_INSN)
2992 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2993 if (GET_CODE (prev) != NOTE
2994 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
3001 /* If this was a conditional jump, we need to also delete
3002 the insn that set cc0. */
3003 if (prev && sets_cc0_p (prev))
3006 prev = prev_nonnote_insn (prev);
3015 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
3016 del_first = NEXT_INSN (a_end);
3018 /* Delete everything marked above as well as crap that might be
3019 hanging out between the two blocks. */
3020 flow_delete_insn_chain (del_first, del_last);
3022 /* Normally there should only be one successor of A and that is B, but
3023 partway though the merge of blocks for conditional_execution we'll
3024 be merging a TEST block with THEN and ELSE successors. Free the
3025 whole lot of them and hope the caller knows what they're doing. */
3027 remove_edge (a->succ);
3029 /* Adjust the edges out of B for the new owner. */
3030 for (e = b->succ; e; e = e->succ_next)
3034 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
3035 b->pred = b->succ = NULL;
3037 /* Reassociate the insns of B with A. */
3040 if (basic_block_for_insn)
3042 BLOCK_FOR_INSN (b_head) = a;
3043 while (b_head != b_end)
3045 b_head = NEXT_INSN (b_head);
3046 BLOCK_FOR_INSN (b_head) = a;
3056 /* Blocks A and B are to be merged into a single block. A has no incoming
3057 fallthru edge, so it can be moved before B without adding or modifying
3058 any jumps (aside from the jump from A to B). */
3061 merge_blocks_move_predecessor_nojumps (a, b)
3064 rtx start, end, barrier;
3070 barrier = next_nonnote_insn (end);
3071 if (GET_CODE (barrier) != BARRIER)
3073 flow_delete_insn (barrier);
3075 /* Move block and loop notes out of the chain so that we do not
3076 disturb their order.
3078 ??? A better solution would be to squeeze out all the non-nested notes
3079 and adjust the block trees appropriately. Even better would be to have
3080 a tighter connection between block trees and rtl so that this is not
3082 start = squeeze_notes (start, end);
3084 /* Scramble the insn chain. */
3085 if (end != PREV_INSN (b->head))
3086 reorder_insns (start, end, PREV_INSN (b->head));
3090 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
3091 a->index, b->index);
3094 /* Swap the records for the two blocks around. Although we are deleting B,
3095 A is now where B was and we want to compact the BB array from where
3097 BASIC_BLOCK (a->index) = b;
3098 BASIC_BLOCK (b->index) = a;
3100 a->index = b->index;
3103 /* Now blocks A and B are contiguous. Merge them. */
3104 merge_blocks_nomove (a, b);
3109 /* Blocks A and B are to be merged into a single block. B has no outgoing
3110 fallthru edge, so it can be moved after A without adding or modifying
3111 any jumps (aside from the jump from A to B). */
3114 merge_blocks_move_successor_nojumps (a, b)
3117 rtx start, end, barrier;
3121 barrier = NEXT_INSN (end);
3123 /* Recognize a jump table following block B. */
3125 && GET_CODE (barrier) == CODE_LABEL
3126 && NEXT_INSN (barrier)
3127 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
3128 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
3129 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
3131 end = NEXT_INSN (barrier);
3132 barrier = NEXT_INSN (end);
3135 /* There had better have been a barrier there. Delete it. */
3136 if (barrier && GET_CODE (barrier) == BARRIER)
3137 flow_delete_insn (barrier);
3139 /* Move block and loop notes out of the chain so that we do not
3140 disturb their order.
3142 ??? A better solution would be to squeeze out all the non-nested notes
3143 and adjust the block trees appropriately. Even better would be to have
3144 a tighter connection between block trees and rtl so that this is not
3146 start = squeeze_notes (start, end);
3148 /* Scramble the insn chain. */
3149 reorder_insns (start, end, a->end);
3151 /* Now blocks A and B are contiguous. Merge them. */
3152 merge_blocks_nomove (a, b);
3156 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
3157 b->index, a->index);
3163 /* Attempt to merge basic blocks that are potentially non-adjacent.
3164 Return true iff the attempt succeeded. */
3167 merge_blocks (e, b, c, mode)
3172 /* If C has a tail recursion label, do not merge. There is no
3173 edge recorded from the call_placeholder back to this label, as
3174 that would make optimize_sibling_and_tail_recursive_calls more
3175 complex for no gain. */
3176 if (GET_CODE (c->head) == CODE_LABEL
3177 && tail_recursion_label_p (c->head))
3180 /* If B has a fallthru edge to C, no need to move anything. */
3181 if (e->flags & EDGE_FALLTHRU)
3183 merge_blocks_nomove (b, c);
3187 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
3188 b->index, c->index);
3193 /* Otherwise we will need to move code around. Do that only if expensive
3194 transformations are allowed. */
3195 else if (mode & CLEANUP_EXPENSIVE)
3197 edge tmp_edge, c_fallthru_edge;
3198 int c_has_outgoing_fallthru;
3199 int b_has_incoming_fallthru;
3201 /* Avoid overactive code motion, as the forwarder blocks should be
3202 eliminated by edge redirection instead. One exception might have
3203 been if B is a forwarder block and C has no fallthru edge, but
3204 that should be cleaned up by bb-reorder instead. */
3205 if (forwarder_block_p (b) || forwarder_block_p (c))
3208 /* We must make sure to not munge nesting of lexical blocks,
3209 and loop notes. This is done by squeezing out all the notes
3210 and leaving them there to lie. Not ideal, but functional. */
3212 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
3213 if (tmp_edge->flags & EDGE_FALLTHRU)
3215 c_has_outgoing_fallthru = (tmp_edge != NULL);
3216 c_fallthru_edge = tmp_edge;
3218 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
3219 if (tmp_edge->flags & EDGE_FALLTHRU)
3221 b_has_incoming_fallthru = (tmp_edge != NULL);
3223 /* If B does not have an incoming fallthru, then it can be moved
3224 immediately before C without introducing or modifying jumps.
3225 C cannot be the first block, so we do not have to worry about
3226 accessing a non-existent block. */
3227 if (! b_has_incoming_fallthru)
3228 return merge_blocks_move_predecessor_nojumps (b, c);
3230 /* Otherwise, we're going to try to move C after B. If C does
3231 not have an outgoing fallthru, then it can be moved
3232 immediately after B without introducing or modifying jumps. */
3233 if (! c_has_outgoing_fallthru)
3234 return merge_blocks_move_successor_nojumps (b, c);
3236 /* Otherwise, we'll need to insert an extra jump, and possibly
3237 a new block to contain it. We can't redirect to EXIT_BLOCK_PTR,
3238 as we don't have explicit return instructions before epilogues
3239 are generated, so give up on that case. */
3241 if (c_fallthru_edge->dest != EXIT_BLOCK_PTR
3242 && merge_blocks_move_successor_nojumps (b, c))
3244 basic_block target = c_fallthru_edge->dest;
3248 /* This is a dirty hack to avoid code duplication.
3250 Set edge to point to wrong basic block, so
3251 redirect_edge_and_branch_force will do the trick
3252 and rewire edge back to the original location. */
3253 redirect_edge_succ (c_fallthru_edge, ENTRY_BLOCK_PTR);
3254 new = redirect_edge_and_branch_force (c_fallthru_edge, target);
3256 /* We've just created barrier, but another barrier is
3257 already present in the stream. Avoid the duplicate. */
3258 barrier = next_nonnote_insn (new ? new->end : b->end);
3259 if (GET_CODE (barrier) != BARRIER)
3261 flow_delete_insn (barrier);
3271 /* Simplify a conditional jump around an unconditional jump.
3272 Return true if something changed. */
3275 try_simplify_condjump (cbranch_block)
3276 basic_block cbranch_block;
3278 basic_block jump_block, jump_dest_block, cbranch_dest_block;
3279 edge cbranch_jump_edge, cbranch_fallthru_edge;
3282 /* Verify that there are exactly two successors. */
3283 if (!cbranch_block->succ
3284 || !cbranch_block->succ->succ_next
3285 || cbranch_block->succ->succ_next->succ_next)
3288 /* Verify that we've got a normal conditional branch at the end
3290 cbranch_insn = cbranch_block->end;
3291 if (!any_condjump_p (cbranch_insn))
3294 cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block);
3295 cbranch_jump_edge = BRANCH_EDGE (cbranch_block);
3297 /* The next block must not have multiple predecessors, must not
3298 be the last block in the function, and must contain just the
3299 unconditional jump. */
3300 jump_block = cbranch_fallthru_edge->dest;
3301 if (jump_block->pred->pred_next
3302 || jump_block->index == n_basic_blocks - 1
3303 || !forwarder_block_p (jump_block))
3305 jump_dest_block = jump_block->succ->dest;
3307 /* The conditional branch must target the block after the
3308 unconditional branch. */
3309 cbranch_dest_block = cbranch_jump_edge->dest;
3311 if (!can_fallthru (jump_block, cbranch_dest_block))
3314 /* Invert the conditional branch. Prevent jump.c from deleting
3315 "unreachable" instructions. */
3316 LABEL_NUSES (JUMP_LABEL (cbranch_insn))++;
3317 if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 1))
3319 LABEL_NUSES (JUMP_LABEL (cbranch_insn))--;
3324 fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n",
3325 INSN_UID (cbranch_insn), INSN_UID (jump_block->end));
3327 /* Success. Update the CFG to match. Note that after this point
3328 the edge variable names appear backwards; the redirection is done
3329 this way to preserve edge profile data. */
3330 redirect_edge_succ_nodup (cbranch_jump_edge, cbranch_dest_block);
3331 redirect_edge_succ_nodup (cbranch_fallthru_edge, jump_dest_block);
3332 cbranch_jump_edge->flags |= EDGE_FALLTHRU;
3333 cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
3335 /* Delete the block with the unconditional jump, and clean up the mess. */
3336 flow_delete_block (jump_block);
3337 tidy_fallthru_edge (cbranch_jump_edge, cbranch_block, cbranch_dest_block);
3342 /* Attempt to forward edges leaving basic block B.
3343 Return true if sucessful. */
3346 try_forward_edges (mode, b)
3350 bool changed = false;
3353 for (e = b->succ; e ; e = next)
3355 basic_block target, first;
3358 next = e->succ_next;
3360 /* Skip complex edges because we don't know how to update them.
3362 Still handle fallthru edges, as we can suceed to forward fallthru
3363 edge to the same place as the branch edge of conditional branch
3364 and turn conditional branch to an unconditonal branch. */
3365 if (e->flags & EDGE_COMPLEX)
3368 target = first = e->dest;
3371 /* Look for the real destination of the jump.
3372 Avoid inifinite loop in the infinite empty loop by counting
3373 up to n_basic_blocks. */
3374 while (forwarder_block_p (target)
3375 && target->succ->dest != EXIT_BLOCK_PTR
3376 && counter < n_basic_blocks)
3378 /* Bypass trivial infinite loops. */
3379 if (target == target->succ->dest)
3380 counter = n_basic_blocks;
3382 /* Avoid killing of loop pre-headers, as it is the place loop
3383 optimizer wants to hoist code to.
3385 For fallthru forwarders, the LOOP_BEG note must appear between
3386 the header of block and CODE_LABEL of the loop, for non forwarders
3387 it must appear before the JUMP_INSN. */
3388 if (mode & CLEANUP_PRE_LOOP)
3390 rtx insn = (target->succ->flags & EDGE_FALLTHRU
3391 ? target->head : prev_nonnote_insn (target->end));
3393 if (GET_CODE (insn) != NOTE)
3394 insn = NEXT_INSN (insn);
3396 for (;insn && GET_CODE (insn) != CODE_LABEL && !INSN_P (insn);
3397 insn = NEXT_INSN (insn))
3398 if (GET_CODE (insn) == NOTE
3399 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
3402 if (GET_CODE (insn) == NOTE)
3405 target = target->succ->dest, counter++;
3408 if (counter >= n_basic_blocks)
3411 fprintf (rtl_dump_file, "Infinite loop in BB %i.\n",
3414 else if (target == first)
3415 ; /* We didn't do anything. */
3418 /* Save the values now, as the edge may get removed. */
3419 gcov_type edge_count = e->count;
3420 int edge_probability = e->probability;
3422 if (redirect_edge_and_branch (e, target))
3424 /* We successfully forwarded the edge. Now update profile
3425 data: for each edge we traversed in the chain, remove
3426 the original edge's execution count. */
3427 int edge_frequency = ((edge_probability * b->frequency
3428 + REG_BR_PROB_BASE / 2)
3429 / REG_BR_PROB_BASE);
3433 first->count -= edge_count;
3434 first->succ->count -= edge_count;
3435 first->frequency -= edge_frequency;
3436 first = first->succ->dest;
3438 while (first != target);
3445 fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n",
3446 b->index, e->dest->index, target->index);
3454 /* Look through the insns at the end of BB1 and BB2 and find the longest
3455 sequence that are equivalent. Store the first insns for that sequence
3456 in *F1 and *F2 and return the sequence length.
3458 To simplify callers of this function, if the blocks match exactly,
3459 store the head of the blocks in *F1 and *F2. */
3462 flow_find_cross_jump (mode, bb1, bb2, f1, f2)
3463 int mode ATTRIBUTE_UNUSED;
3464 basic_block bb1, bb2;
3467 rtx i1, i2, p1, p2, last1, last2, afterlast1, afterlast2;
3470 /* Skip simple jumps at the end of the blocks. Complex jumps still
3471 need to be compared for equivalence, which we'll do below. */
3474 if (onlyjump_p (i1))
3475 i1 = PREV_INSN (i1);
3477 if (onlyjump_p (i2))
3478 i2 = PREV_INSN (i2);
3480 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
3484 while ((GET_CODE (i1) == NOTE && i1 != bb1->head))
3485 i1 = PREV_INSN (i1);
3486 while ((GET_CODE (i2) == NOTE && i2 != bb2->head))
3487 i2 = PREV_INSN (i2);
3489 if (i1 == bb1->head || i2 == bb2->head)
3492 /* Verify that I1 and I2 are equivalent. */
3494 if (GET_CODE (i1) != GET_CODE (i2))
3500 /* If this is a CALL_INSN, compare register usage information.
3501 If we don't check this on stack register machines, the two
3502 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3503 numbers of stack registers in the same basic block.
3504 If we don't check this on machines with delay slots, a delay slot may
3505 be filled that clobbers a parameter expected by the subroutine.
3507 ??? We take the simple route for now and assume that if they're
3508 equal, they were constructed identically. */
3510 if (GET_CODE (i1) == CALL_INSN
3511 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3512 CALL_INSN_FUNCTION_USAGE (i2)))
3516 /* If cross_jump_death_matters is not 0, the insn's mode
3517 indicates whether or not the insn contains any stack-like
3520 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
3522 /* If register stack conversion has already been done, then
3523 death notes must also be compared before it is certain that
3524 the two instruction streams match. */
3527 HARD_REG_SET i1_regset, i2_regset;
3529 CLEAR_HARD_REG_SET (i1_regset);
3530 CLEAR_HARD_REG_SET (i2_regset);
3532 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3533 if (REG_NOTE_KIND (note) == REG_DEAD
3534 && STACK_REG_P (XEXP (note, 0)))
3535 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3537 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3538 if (REG_NOTE_KIND (note) == REG_DEAD
3539 && STACK_REG_P (XEXP (note, 0)))
3540 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3542 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3551 if (GET_CODE (p1) != GET_CODE (p2))
3554 if (! rtx_renumbered_equal_p (p1, p2))
3556 /* The following code helps take care of G++ cleanups. */
3557 rtx equiv1 = find_reg_equal_equiv_note (i1);
3558 rtx equiv2 = find_reg_equal_equiv_note (i2);
3560 if (equiv1 && equiv2
3561 /* If the equivalences are not to a constant, they may
3562 reference pseudos that no longer exist, so we can't
3564 && CONSTANT_P (XEXP (equiv1, 0))
3565 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3567 rtx s1 = single_set (i1);
3568 rtx s2 = single_set (i2);
3569 if (s1 != 0 && s2 != 0
3570 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3572 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3573 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3574 if (! rtx_renumbered_equal_p (p1, p2))
3576 else if (apply_change_group ())
3584 /* Don't begin a cross-jump with a USE or CLOBBER insn. */
3585 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3587 afterlast1 = last1, afterlast2 = last2;
3588 last1 = i1, last2 = i2;
3591 i1 = PREV_INSN (i1);
3592 i2 = PREV_INSN (i2);
3598 /* Don't allow the insn after a compare to be shared by
3599 cross-jumping unless the compare is also shared. */
3600 if (reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1))
3601 last1 = afterlast1, last2 = afterlast2, ninsns--;
3605 /* Include preceeding notes and labels in the cross-jump. One,
3606 this may bring us to the head of the blocks as requested above.
3607 Two, it keeps line number notes as matched as may be. */
3610 while (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == NOTE)
3611 last1 = PREV_INSN (last1);
3612 if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL)
3613 last1 = PREV_INSN (last1);
3614 while (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == NOTE)
3615 last2 = PREV_INSN (last2);
3616 if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL)
3617 last2 = PREV_INSN (last2);
3626 /* Return true iff outgoing edges of BB1 and BB2 match, together with
3627 the branch instruction. This means that if we commonize the control
3628 flow before end of the basic block, the semantic remains unchanged.
3630 We may assume that there exists one edge with a common destination. */
3633 outgoing_edges_match (bb1, bb2)
3637 /* If BB1 has only one successor, we must be looking at an unconditional
3638 jump. Which, by the assumption above, means that we only need to check
3639 that BB2 has one successor. */
3640 if (bb1->succ && !bb1->succ->succ_next)
3641 return (bb2->succ && !bb2->succ->succ_next);
3643 /* Match conditional jumps - this may get tricky when fallthru and branch
3644 edges are crossed. */
3646 && bb1->succ->succ_next
3647 && !bb1->succ->succ_next->succ_next
3648 && any_condjump_p (bb1->end))
3650 edge b1, f1, b2, f2;
3651 bool reverse, match;
3652 rtx set1, set2, cond1, cond2;
3653 enum rtx_code code1, code2;
3656 || !bb2->succ->succ_next
3657 || bb1->succ->succ_next->succ_next
3658 || !any_condjump_p (bb2->end))
3661 b1 = BRANCH_EDGE (bb1);
3662 b2 = BRANCH_EDGE (bb2);
3663 f1 = FALLTHRU_EDGE (bb1);
3664 f2 = FALLTHRU_EDGE (bb2);
3666 /* Get around possible forwarders on fallthru edges. Other cases
3667 should be optimized out already. */
3668 if (forwarder_block_p (f1->dest))
3669 f1 = f1->dest->succ;
3670 if (forwarder_block_p (f2->dest))
3671 f2 = f2->dest->succ;
3673 /* To simplify use of this function, return false if there are
3674 unneeded forwarder blocks. These will get eliminated later
3675 during cleanup_cfg. */
3676 if (forwarder_block_p (f1->dest)
3677 || forwarder_block_p (f2->dest)
3678 || forwarder_block_p (b1->dest)
3679 || forwarder_block_p (b2->dest))
3682 if (f1->dest == f2->dest && b1->dest == b2->dest)
3684 else if (f1->dest == b2->dest && b1->dest == f2->dest)
3689 set1 = pc_set (bb1->end);
3690 set2 = pc_set (bb2->end);
3691 if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
3692 != (XEXP (SET_SRC (set2), 1) == pc_rtx))
3695 cond1 = XEXP (SET_SRC (set1), 0);
3696 cond2 = XEXP (SET_SRC (set2), 0);
3697 code1 = GET_CODE (cond1);
3699 code2 = reversed_comparison_code (cond2, bb2->end);
3701 code2 = GET_CODE (cond2);
3702 if (code2 == UNKNOWN)
3705 /* Verify codes and operands match. */
3706 match = ((code1 == code2
3707 && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
3708 && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
3709 || (code1 == swap_condition (code2)
3710 && rtx_renumbered_equal_p (XEXP (cond1, 1),
3712 && rtx_renumbered_equal_p (XEXP (cond1, 0),
3715 /* If we return true, we will join the blocks. Which means that
3716 we will only have one branch prediction bit to work with. Thus
3717 we require the existing branches to have probabilities that are
3719 /* ??? We should use bb->frequency to allow merging in infrequently
3720 executed blocks, but at the moment it is not available when
3721 cleanup_cfg is run. */
3722 if (match && !optimize_size)
3726 note1 = find_reg_note (bb1->end, REG_BR_PROB, 0);
3727 note2 = find_reg_note (bb2->end, REG_BR_PROB, 0);
3731 prob1 = INTVAL (XEXP (note1, 0));
3732 prob2 = INTVAL (XEXP (note2, 0));
3734 prob2 = REG_BR_PROB_BASE - prob2;
3736 /* Fail if the difference in probabilities is
3738 if (abs (prob1 - prob2) > REG_BR_PROB_BASE / 20)
3741 else if (note1 || note2)
3745 if (rtl_dump_file && match)
3746 fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n",
3747 bb1->index, bb2->index);
3752 /* ??? We can handle computed jumps too. This may be important for
3753 inlined functions containing switch statements. Also jumps w/o
3754 fallthru edges can be handled by simply matching whole insn. */
3758 /* E1 and E2 are edges with the same destination block. Search their
3759 predecessors for common code. If found, redirect control flow from
3760 (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */
3763 try_crossjump_to_edge (mode, e1, e2)
3768 basic_block src1 = e1->src, src2 = e2->src;
3769 basic_block redirect_to;
3770 rtx newpos1, newpos2;
3776 /* Search backward through forwarder blocks. We don't need to worry
3777 about multiple entry or chained forwarders, as they will be optimized
3778 away. We do this to look past the unconditional jump following a
3779 conditional jump that is required due to the current CFG shape. */
3781 && !src1->pred->pred_next
3782 && forwarder_block_p (src1))
3788 && !src2->pred->pred_next
3789 && forwarder_block_p (src2))
3795 /* Nothing to do if we reach ENTRY, or a common source block. */
3796 if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR)
3801 /* Seeing more than 1 forwarder blocks would confuse us later... */
3802 if (forwarder_block_p (e1->dest)
3803 && forwarder_block_p (e1->dest->succ->dest))
3805 if (forwarder_block_p (e2->dest)
3806 && forwarder_block_p (e2->dest->succ->dest))
3809 /* Likewise with dead code (possibly newly created by the other optimizations
3811 if (!src1->pred || !src2->pred)
3814 /* Likewise with complex edges.
3815 ??? We should be able to handle most complex edges later with some
3817 if (e1->flags & EDGE_COMPLEX)
3820 /* Look for the common insn sequence, part the first ... */
3821 if (!outgoing_edges_match (src1, src2))
3824 /* ... and part the second. */
3825 nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2);
3829 /* Avoid splitting if possible. */
3830 if (newpos2 == src2->head)
3835 fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n",
3836 src2->index, nmatch);
3837 redirect_to = split_block (src2, PREV_INSN (newpos2))->dest;
3841 fprintf (rtl_dump_file,
3842 "Cross jumping from bb %i to bb %i; %i common insns\n",
3843 src1->index, src2->index, nmatch);
3845 redirect_to->count += src1->count;
3846 redirect_to->frequency += src1->frequency;
3848 /* Recompute the frequencies and counts of outgoing edges. */
3849 for (s = redirect_to->succ; s; s = s->succ_next)
3852 basic_block d = s->dest;
3854 if (forwarder_block_p (d))
3856 for (s2 = src1->succ; ; s2 = s2->succ_next)
3858 basic_block d2 = s2->dest;
3859 if (forwarder_block_p (d2))
3860 d2 = d2->succ->dest;
3864 s->count += s2->count;
3866 /* Take care to update possible forwarder blocks. We verified
3867 that there is no more than one in the chain, so we can't run
3868 into infinite loop. */
3869 if (forwarder_block_p (s->dest))
3871 s->dest->succ->count += s2->count;
3872 s->dest->count += s2->count;
3873 s->dest->frequency += EDGE_FREQUENCY (s);
3875 if (forwarder_block_p (s2->dest))
3877 s2->dest->succ->count -= s2->count;
3878 s2->dest->count -= s2->count;
3879 s2->dest->frequency -= EDGE_FREQUENCY (s);
3881 if (!redirect_to->frequency && !src1->frequency)
3882 s->probability = (s->probability + s2->probability) / 2;
3885 ((s->probability * redirect_to->frequency +
3886 s2->probability * src1->frequency)
3887 / (redirect_to->frequency + src1->frequency));
3890 note = find_reg_note (redirect_to->end, REG_BR_PROB, 0);
3892 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (redirect_to)->probability);
3894 /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */
3896 /* Skip possible basic block header. */
3897 if (GET_CODE (newpos1) == CODE_LABEL)
3898 newpos1 = NEXT_INSN (newpos1);
3899 if (GET_CODE (newpos1) == NOTE)
3900 newpos1 = NEXT_INSN (newpos1);
3903 /* Emit the jump insn. */
3904 label = block_label (redirect_to);
3905 src1->end = emit_jump_insn_before (gen_jump (label), newpos1);
3906 JUMP_LABEL (src1->end) = label;
3907 LABEL_NUSES (label)++;
3908 if (basic_block_for_insn)
3909 set_block_for_new_insns (src1->end, src1);
3911 /* Delete the now unreachable instructions. */
3912 flow_delete_insn_chain (newpos1, last);
3914 /* Make sure there is a barrier after the new jump. */
3915 last = next_nonnote_insn (src1->end);
3916 if (!last || GET_CODE (last) != BARRIER)
3917 emit_barrier_after (src1->end);
3921 remove_edge (src1->succ);
3922 make_edge (NULL, src1, redirect_to, 0);
3923 src1->succ->probability = REG_BR_PROB_BASE;
3924 src1->succ->count = src1->count;
3929 /* Search the predecessors of BB for common insn sequences. When found,
3930 share code between them by redirecting control flow. Return true if
3931 any changes made. */
3934 try_crossjump_bb (mode, bb)
3938 edge e, e2, nexte2, nexte, fallthru;
3941 /* Nothing to do if there is not at least two incomming edges. */
3942 if (!bb->pred || !bb->pred->pred_next)
3945 /* It is always cheapest to redirect a block that ends in a branch to
3946 a block that falls through into BB, as that adds no branches to the
3947 program. We'll try that combination first. */
3948 for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next)
3949 if (fallthru->flags & EDGE_FALLTHRU)
3953 for (e = bb->pred; e; e = nexte)
3955 nexte = e->pred_next;
3957 /* Elide complex edges now, as neither try_crossjump_to_edge
3958 nor outgoing_edges_match can handle them. */
3959 if (e->flags & EDGE_COMPLEX)
3962 /* As noted above, first try with the fallthru predecessor. */
3965 /* Don't combine the fallthru edge into anything else.
3966 If there is a match, we'll do it the other way around. */
3970 if (try_crossjump_to_edge (mode, e, fallthru))
3978 /* Non-obvious work limiting check: Recognize that we're going
3979 to call try_crossjump_bb on every basic block. So if we have
3980 two blocks with lots of outgoing edges (a switch) and they
3981 share lots of common destinations, then we would do the
3982 cross-jump check once for each common destination.
3984 Now, if the blocks actually are cross-jump candidates, then
3985 all of their destinations will be shared. Which means that
3986 we only need check them for cross-jump candidacy once. We
3987 can eliminate redundant checks of crossjump(A,B) by arbitrarily
3988 choosing to do the check from the block for which the edge
3989 in question is the first successor of A. */
3990 if (e->src->succ != e)
3993 for (e2 = bb->pred; e2; e2 = nexte2)
3995 nexte2 = e2->pred_next;
4000 /* We've already checked the fallthru edge above. */
4004 /* Again, neither try_crossjump_to_edge nor outgoing_edges_match
4005 can handle complex edges. */
4006 if (e2->flags & EDGE_COMPLEX)
4009 /* The "first successor" check above only prevents multiple
4010 checks of crossjump(A,B). In order to prevent redundant
4011 checks of crossjump(B,A), require that A be the block
4012 with the lowest index. */
4013 if (e->src->index > e2->src->index)
4016 if (try_crossjump_to_edge (mode, e, e2))
4028 /* Do simple CFG optimizations - basic block merging, simplifying of jump
4029 instructions etc. Return nonzero if changes were made. */
4032 try_optimize_cfg (mode)
4036 bool changed_overall = false;
4040 /* Attempt to merge blocks as made possible by edge removal. If a block
4041 has only one successor, and the successor has only one predecessor,
4042 they may be combined. */
4050 fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n",
4053 for (i = 0; i < n_basic_blocks;)
4055 basic_block c, b = BASIC_BLOCK (i);
4057 bool changed_here = false;
4059 /* Delete trivially dead basic blocks. */
4060 while (b->pred == NULL)
4062 c = BASIC_BLOCK (b->index - 1);
4064 fprintf (rtl_dump_file, "Deleting block %i.\n", b->index);
4065 flow_delete_block (b);
4070 /* Remove code labels no longer used. Don't do this before
4071 CALL_PLACEHOLDER is removed, as some branches may be hidden
4073 if (b->pred->pred_next == NULL
4074 && (b->pred->flags & EDGE_FALLTHRU)
4075 && !(b->pred->flags & EDGE_COMPLEX)
4076 && GET_CODE (b->head) == CODE_LABEL
4077 && (!(mode & CLEANUP_PRE_SIBCALL)
4078 || !tail_recursion_label_p (b->head))
4079 /* If previous block ends with condjump jumping to next BB,
4080 we can't delete the label. */
4081 && (b->pred->src == ENTRY_BLOCK_PTR
4082 || !reg_mentioned_p (b->head, b->pred->src->end)))
4084 rtx label = b->head;
4085 b->head = NEXT_INSN (b->head);
4086 flow_delete_insn_chain (label, label);
4088 fprintf (rtl_dump_file, "Deleted label in block %i.\n",
4092 /* If we fall through an empty block, we can remove it. */
4093 if (b->pred->pred_next == NULL
4094 && (b->pred->flags & EDGE_FALLTHRU)
4095 && GET_CODE (b->head) != CODE_LABEL
4096 && forwarder_block_p (b)
4097 /* Note that forwarder_block_p true ensures that there
4098 is a successor for this block. */
4099 && (b->succ->flags & EDGE_FALLTHRU)
4100 && n_basic_blocks > 1)
4103 fprintf (rtl_dump_file, "Deleting fallthru block %i.\n",
4105 c = BASIC_BLOCK (b->index ? b->index - 1 : 1);
4106 redirect_edge_succ_nodup (b->pred, b->succ->dest);
4107 flow_delete_block (b);
4112 /* Merge blocks. Loop because chains of blocks might be
4114 while ((s = b->succ) != NULL
4115 && s->succ_next == NULL
4116 && !(s->flags & EDGE_COMPLEX)
4117 && (c = s->dest) != EXIT_BLOCK_PTR
4118 && c->pred->pred_next == NULL
4119 /* If the jump insn has side effects,
4120 we can't kill the edge. */
4121 && (GET_CODE (b->end) != JUMP_INSN
4122 || onlyjump_p (b->end))
4123 && merge_blocks (s, b, c, mode))
4124 changed_here = true;
4126 /* Simplify branch over branch. */
4127 if ((mode & CLEANUP_EXPENSIVE) && try_simplify_condjump (b))
4128 changed_here = true;
4130 /* If B has a single outgoing edge, but uses a non-trivial jump
4131 instruction without side-effects, we can either delete the
4132 jump entirely, or replace it with a simple unconditional jump.
4133 Use redirect_edge_and_branch to do the dirty work. */
4135 && ! b->succ->succ_next
4136 && b->succ->dest != EXIT_BLOCK_PTR
4137 && onlyjump_p (b->end)
4138 && redirect_edge_and_branch (b->succ, b->succ->dest))
4139 changed_here = true;
4141 /* Simplify branch to branch. */
4142 if (try_forward_edges (mode, b))
4143 changed_here = true;
4145 /* Look for shared code between blocks. */
4146 if ((mode & CLEANUP_CROSSJUMP)
4147 && try_crossjump_bb (mode, b))
4148 changed_here = true;
4150 /* Don't get confused by the index shift caused by deleting
4158 if ((mode & CLEANUP_CROSSJUMP)
4159 && try_crossjump_bb (mode, EXIT_BLOCK_PTR))
4162 #ifdef ENABLE_CHECKING
4164 verify_flow_info ();
4167 changed_overall |= changed;
4170 return changed_overall;
4173 /* The given edge should potentially be a fallthru edge. If that is in
4174 fact true, delete the jump and barriers that are in the way. */
4177 tidy_fallthru_edge (e, b, c)
4183 /* ??? In a late-running flow pass, other folks may have deleted basic
4184 blocks by nopping out blocks, leaving multiple BARRIERs between here
4185 and the target label. They ought to be chastized and fixed.
4187 We can also wind up with a sequence of undeletable labels between
4188 one block and the next.
4190 So search through a sequence of barriers, labels, and notes for
4191 the head of block C and assert that we really do fall through. */
4193 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
4196 /* Remove what will soon cease being the jump insn from the source block.
4197 If block B consisted only of this single jump, turn it into a deleted
4200 if (GET_CODE (q) == JUMP_INSN
4202 && (any_uncondjump_p (q)
4203 || (b->succ == e && e->succ_next == NULL)))
4206 /* If this was a conditional jump, we need to also delete
4207 the insn that set cc0. */
4208 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
4215 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
4216 NOTE_SOURCE_FILE (q) = 0;
4222 /* We don't want a block to end on a line-number note since that has
4223 the potential of changing the code between -g and not -g. */
4224 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
4231 /* Selectively unlink the sequence. */
4232 if (q != PREV_INSN (c->head))
4233 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
4235 e->flags |= EDGE_FALLTHRU;
4238 /* Fix up edges that now fall through, or rather should now fall through
4239 but previously required a jump around now deleted blocks. Simplify
4240 the search by only examining blocks numerically adjacent, since this
4241 is how find_basic_blocks created them. */
4244 tidy_fallthru_edges ()
4248 for (i = 1; i < n_basic_blocks; ++i)
4250 basic_block b = BASIC_BLOCK (i - 1);
4251 basic_block c = BASIC_BLOCK (i);
4254 /* We care about simple conditional or unconditional jumps with
4257 If we had a conditional branch to the next instruction when
4258 find_basic_blocks was called, then there will only be one
4259 out edge for the block which ended with the conditional
4260 branch (since we do not create duplicate edges).
4262 Furthermore, the edge will be marked as a fallthru because we
4263 merge the flags for the duplicate edges. So we do not want to
4264 check that the edge is not a FALLTHRU edge. */
4265 if ((s = b->succ) != NULL
4266 && ! (s->flags & EDGE_COMPLEX)
4267 && s->succ_next == NULL
4269 /* If the jump insn has side effects, we can't tidy the edge. */
4270 && (GET_CODE (b->end) != JUMP_INSN
4271 || onlyjump_p (b->end)))
4272 tidy_fallthru_edge (s, b, c);
4276 /* Perform data flow analysis.
4277 F is the first insn of the function; FLAGS is a set of PROP_* flags
4278 to be used in accumulating flow info. */
4281 life_analysis (f, file, flags)
4286 #ifdef ELIMINABLE_REGS
4288 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
4291 /* Record which registers will be eliminated. We use this in
4294 CLEAR_HARD_REG_SET (elim_reg_set);
4296 #ifdef ELIMINABLE_REGS
4297 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
4298 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
4300 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
4304 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
4306 /* The post-reload life analysis have (on a global basis) the same
4307 registers live as was computed by reload itself. elimination
4308 Otherwise offsets and such may be incorrect.
4310 Reload will make some registers as live even though they do not
4313 We don't want to create new auto-incs after reload, since they
4314 are unlikely to be useful and can cause problems with shared
4316 if (reload_completed)
4317 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
4319 /* We want alias analysis information for local dead store elimination. */
4320 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4321 init_alias_analysis ();
4323 /* Always remove no-op moves. Do this before other processing so
4324 that we don't have to keep re-scanning them. */
4325 delete_noop_moves (f);
4327 /* Some targets can emit simpler epilogues if they know that sp was
4328 not ever modified during the function. After reload, of course,
4329 we've already emitted the epilogue so there's no sense searching. */
4330 if (! reload_completed)
4331 notice_stack_pointer_modification (f);
4333 /* Allocate and zero out data structures that will record the
4334 data from lifetime analysis. */
4335 allocate_reg_life_data ();
4336 allocate_bb_life_data ();
4338 /* Find the set of registers live on function exit. */
4339 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
4341 /* "Update" life info from zero. It'd be nice to begin the
4342 relaxation with just the exit and noreturn blocks, but that set
4343 is not immediately handy. */
4345 if (flags & PROP_REG_INFO)
4346 memset (regs_ever_live, 0, sizeof (regs_ever_live));
4347 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
4350 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4351 end_alias_analysis ();
4354 dump_flow_info (file);
4356 free_basic_block_vars (1);
4358 #ifdef ENABLE_CHECKING
4362 /* Search for any REG_LABEL notes which reference deleted labels. */
4363 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4365 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4367 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
4372 /* Removing dead insns should've made jumptables really dead. */
4373 delete_dead_jumptables ();
4376 /* A subroutine of verify_wide_reg, called through for_each_rtx.
4377 Search for REGNO. If found, abort if it is not wider than word_mode. */
4380 verify_wide_reg_1 (px, pregno)
4385 unsigned int regno = *(int *) pregno;
4387 if (GET_CODE (x) == REG && REGNO (x) == regno)
4389 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
4396 /* A subroutine of verify_local_live_at_start. Search through insns
4397 between HEAD and END looking for register REGNO. */
4400 verify_wide_reg (regno, head, end)
4407 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
4411 head = NEXT_INSN (head);
4414 /* We didn't find the register at all. Something's way screwy. */
4416 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
4417 print_rtl_and_abort ();
4420 /* A subroutine of update_life_info. Verify that there are no untoward
4421 changes in live_at_start during a local update. */
4424 verify_local_live_at_start (new_live_at_start, bb)
4425 regset new_live_at_start;
4428 if (reload_completed)
4430 /* After reload, there are no pseudos, nor subregs of multi-word
4431 registers. The regsets should exactly match. */
4432 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
4436 fprintf (rtl_dump_file,
4437 "live_at_start mismatch in bb %d, aborting\n",
4439 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
4440 debug_bitmap_file (rtl_dump_file, new_live_at_start);
4442 print_rtl_and_abort ();
4449 /* Find the set of changed registers. */
4450 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
4452 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
4454 /* No registers should die. */
4455 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
4458 fprintf (rtl_dump_file,
4459 "Register %d died unexpectedly in block %d\n", i,
4461 print_rtl_and_abort ();
4464 /* Verify that the now-live register is wider than word_mode. */
4465 verify_wide_reg (i, bb->head, bb->end);
4470 /* Updates life information starting with the basic blocks set in BLOCKS.
4471 If BLOCKS is null, consider it to be the universal set.
4473 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
4474 we are only expecting local modifications to basic blocks. If we find
4475 extra registers live at the beginning of a block, then we either killed
4476 useful data, or we have a broken split that wants data not provided.
4477 If we find registers removed from live_at_start, that means we have
4478 a broken peephole that is killing a register it shouldn't.
4480 ??? This is not true in one situation -- when a pre-reload splitter
4481 generates subregs of a multi-word pseudo, current life analysis will
4482 lose the kill. So we _can_ have a pseudo go live. How irritating.
4484 Including PROP_REG_INFO does not properly refresh regs_ever_live
4485 unless the caller resets it to zero. */
4488 update_life_info (blocks, extent, prop_flags)
4490 enum update_life_extent extent;
4494 regset_head tmp_head;
4497 tmp = INITIALIZE_REG_SET (tmp_head);
4499 /* Changes to the CFG are only allowed when
4500 doing a global update for the entire CFG. */
4501 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
4502 && (extent == UPDATE_LIFE_LOCAL || blocks))
4505 /* For a global update, we go through the relaxation process again. */
4506 if (extent != UPDATE_LIFE_LOCAL)
4512 calculate_global_regs_live (blocks, blocks,
4513 prop_flags & (PROP_SCAN_DEAD_CODE
4514 | PROP_ALLOW_CFG_CHANGES));
4516 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
4517 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
4520 /* Removing dead code may allow the CFG to be simplified which
4521 in turn may allow for further dead code detection / removal. */
4522 for (i = n_basic_blocks - 1; i >= 0; --i)
4524 basic_block bb = BASIC_BLOCK (i);
4526 COPY_REG_SET (tmp, bb->global_live_at_end);
4527 changed |= propagate_block (bb, tmp, NULL, NULL,
4528 prop_flags & (PROP_SCAN_DEAD_CODE
4529 | PROP_KILL_DEAD_CODE));
4532 if (! changed || ! try_optimize_cfg (CLEANUP_EXPENSIVE))
4535 delete_unreachable_blocks ();
4536 mark_critical_edges ();
4539 /* If asked, remove notes from the blocks we'll update. */
4540 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
4541 count_or_remove_death_notes (blocks, 1);
4546 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4548 basic_block bb = BASIC_BLOCK (i);
4550 COPY_REG_SET (tmp, bb->global_live_at_end);
4551 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4553 if (extent == UPDATE_LIFE_LOCAL)
4554 verify_local_live_at_start (tmp, bb);
4559 for (i = n_basic_blocks - 1; i >= 0; --i)
4561 basic_block bb = BASIC_BLOCK (i);
4563 COPY_REG_SET (tmp, bb->global_live_at_end);
4564 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4566 if (extent == UPDATE_LIFE_LOCAL)
4567 verify_local_live_at_start (tmp, bb);
4573 if (prop_flags & PROP_REG_INFO)
4575 /* The only pseudos that are live at the beginning of the function
4576 are those that were not set anywhere in the function. local-alloc
4577 doesn't know how to handle these correctly, so mark them as not
4578 local to any one basic block. */
4579 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
4580 FIRST_PSEUDO_REGISTER, i,
4581 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4583 /* We have a problem with any pseudoreg that lives across the setjmp.
4584 ANSI says that if a user variable does not change in value between
4585 the setjmp and the longjmp, then the longjmp preserves it. This
4586 includes longjmp from a place where the pseudo appears dead.
4587 (In principle, the value still exists if it is in scope.)
4588 If the pseudo goes in a hard reg, some other value may occupy
4589 that hard reg where this pseudo is dead, thus clobbering the pseudo.
4590 Conclusion: such a pseudo must not go in a hard reg. */
4591 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
4592 FIRST_PSEUDO_REGISTER, i,
4594 if (regno_reg_rtx[i] != 0)
4596 REG_LIVE_LENGTH (i) = -1;
4597 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4603 /* Free the variables allocated by find_basic_blocks.
4605 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
4608 free_basic_block_vars (keep_head_end_p)
4609 int keep_head_end_p;
4611 if (basic_block_for_insn)
4613 VARRAY_FREE (basic_block_for_insn);
4614 basic_block_for_insn = NULL;
4617 if (! keep_head_end_p)
4619 if (basic_block_info)
4622 VARRAY_FREE (basic_block_info);
4626 ENTRY_BLOCK_PTR->aux = NULL;
4627 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
4628 EXIT_BLOCK_PTR->aux = NULL;
4629 EXIT_BLOCK_PTR->global_live_at_start = NULL;
4633 /* Delete any insns that copy a register to itself. */
4636 delete_noop_moves (f)
4637 rtx f ATTRIBUTE_UNUSED;
4643 for (i = 0; i < n_basic_blocks; i++)
4645 bb = BASIC_BLOCK (i);
4646 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
4648 next = NEXT_INSN (insn);
4649 if (INSN_P (insn) && noop_move_p (insn))
4651 /* Do not call flow_delete_insn here to not confuse backward
4652 pointers of LIBCALL block. */
4653 PUT_CODE (insn, NOTE);
4654 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
4655 NOTE_SOURCE_FILE (insn) = 0;
4661 /* Delete any jump tables never referenced. We can't delete them at the
4662 time of removing tablejump insn as they are referenced by the preceeding
4663 insns computing the destination, so we delay deleting and garbagecollect
4664 them once life information is computed. */
4666 delete_dead_jumptables ()
4669 for (insn = get_insns (); insn; insn = next)
4671 next = NEXT_INSN (insn);
4672 if (GET_CODE (insn) == CODE_LABEL
4673 && LABEL_NUSES (insn) == 0
4674 && GET_CODE (next) == JUMP_INSN
4675 && (GET_CODE (PATTERN (next)) == ADDR_VEC
4676 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
4679 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
4680 flow_delete_insn (NEXT_INSN (insn));
4681 flow_delete_insn (insn);
4682 next = NEXT_INSN (next);
4687 /* Determine if the stack pointer is constant over the life of the function.
4688 Only useful before prologues have been emitted. */
4691 notice_stack_pointer_modification_1 (x, pat, data)
4693 rtx pat ATTRIBUTE_UNUSED;
4694 void *data ATTRIBUTE_UNUSED;
4696 if (x == stack_pointer_rtx
4697 /* The stack pointer is only modified indirectly as the result
4698 of a push until later in flow. See the comments in rtl.texi
4699 regarding Embedded Side-Effects on Addresses. */
4700 || (GET_CODE (x) == MEM
4701 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
4702 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
4703 current_function_sp_is_unchanging = 0;
4707 notice_stack_pointer_modification (f)
4712 /* Assume that the stack pointer is unchanging if alloca hasn't
4714 current_function_sp_is_unchanging = !current_function_calls_alloca;
4715 if (! current_function_sp_is_unchanging)
4718 for (insn = f; insn; insn = NEXT_INSN (insn))
4722 /* Check if insn modifies the stack pointer. */
4723 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
4725 if (! current_function_sp_is_unchanging)
4731 /* Mark a register in SET. Hard registers in large modes get all
4732 of their component registers set as well. */
4735 mark_reg (reg, xset)
4739 regset set = (regset) xset;
4740 int regno = REGNO (reg);
4742 if (GET_MODE (reg) == BLKmode)
4745 SET_REGNO_REG_SET (set, regno);
4746 if (regno < FIRST_PSEUDO_REGISTER)
4748 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
4750 SET_REGNO_REG_SET (set, regno + n);
4754 /* Mark those regs which are needed at the end of the function as live
4755 at the end of the last basic block. */
4758 mark_regs_live_at_end (set)
4763 /* If exiting needs the right stack value, consider the stack pointer
4764 live at the end of the function. */
4765 if ((HAVE_epilogue && reload_completed)
4766 || ! EXIT_IGNORE_STACK
4767 || (! FRAME_POINTER_REQUIRED
4768 && ! current_function_calls_alloca
4769 && flag_omit_frame_pointer)
4770 || current_function_sp_is_unchanging)
4772 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
4775 /* Mark the frame pointer if needed at the end of the function. If
4776 we end up eliminating it, it will be removed from the live list
4777 of each basic block by reload. */
4779 if (! reload_completed || frame_pointer_needed)
4781 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
4782 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4783 /* If they are different, also mark the hard frame pointer as live. */
4784 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
4785 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
4789 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
4790 /* Many architectures have a GP register even without flag_pic.
4791 Assume the pic register is not in use, or will be handled by
4792 other means, if it is not fixed. */
4793 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4794 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4795 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
4798 /* Mark all global registers, and all registers used by the epilogue
4799 as being live at the end of the function since they may be
4800 referenced by our caller. */
4801 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4802 if (global_regs[i] || EPILOGUE_USES (i))
4803 SET_REGNO_REG_SET (set, i);
4805 if (HAVE_epilogue && reload_completed)
4807 /* Mark all call-saved registers that we actually used. */
4808 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4809 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
4810 SET_REGNO_REG_SET (set, i);
4813 #ifdef EH_RETURN_DATA_REGNO
4814 /* Mark the registers that will contain data for the handler. */
4815 if (reload_completed && current_function_calls_eh_return)
4818 unsigned regno = EH_RETURN_DATA_REGNO(i);
4819 if (regno == INVALID_REGNUM)
4821 SET_REGNO_REG_SET (set, regno);
4824 #ifdef EH_RETURN_STACKADJ_RTX
4825 if ((! HAVE_epilogue || ! reload_completed)
4826 && current_function_calls_eh_return)
4828 rtx tmp = EH_RETURN_STACKADJ_RTX;
4829 if (tmp && REG_P (tmp))
4830 mark_reg (tmp, set);
4833 #ifdef EH_RETURN_HANDLER_RTX
4834 if ((! HAVE_epilogue || ! reload_completed)
4835 && current_function_calls_eh_return)
4837 rtx tmp = EH_RETURN_HANDLER_RTX;
4838 if (tmp && REG_P (tmp))
4839 mark_reg (tmp, set);
4843 /* Mark function return value. */
4844 diddle_return_value (mark_reg, set);
4847 /* Callback function for for_each_successor_phi. DATA is a regset.
4848 Sets the SRC_REGNO, the regno of the phi alternative for phi node
4849 INSN, in the regset. */
4852 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
4853 rtx insn ATTRIBUTE_UNUSED;
4854 int dest_regno ATTRIBUTE_UNUSED;
4858 regset live = (regset) data;
4859 SET_REGNO_REG_SET (live, src_regno);
4863 /* Propagate global life info around the graph of basic blocks. Begin
4864 considering blocks with their corresponding bit set in BLOCKS_IN.
4865 If BLOCKS_IN is null, consider it the universal set.
4867 BLOCKS_OUT is set for every block that was changed. */
4870 calculate_global_regs_live (blocks_in, blocks_out, flags)
4871 sbitmap blocks_in, blocks_out;
4874 basic_block *queue, *qhead, *qtail, *qend;
4875 regset tmp, new_live_at_end, call_used;
4876 regset_head tmp_head, call_used_head;
4877 regset_head new_live_at_end_head;
4880 tmp = INITIALIZE_REG_SET (tmp_head);
4881 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
4882 call_used = INITIALIZE_REG_SET (call_used_head);
4884 /* Inconveniently, this is only redily available in hard reg set form. */
4885 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
4886 if (call_used_regs[i])
4887 SET_REGNO_REG_SET (call_used, i);
4889 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
4890 because the `head == tail' style test for an empty queue doesn't
4891 work with a full queue. */
4892 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
4894 qhead = qend = queue + n_basic_blocks + 2;
4896 /* Queue the blocks set in the initial mask. Do this in reverse block
4897 number order so that we are more likely for the first round to do
4898 useful work. We use AUX non-null to flag that the block is queued. */
4901 /* Clear out the garbage that might be hanging out in bb->aux. */
4902 for (i = n_basic_blocks - 1; i >= 0; --i)
4903 BASIC_BLOCK (i)->aux = NULL;
4905 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
4907 basic_block bb = BASIC_BLOCK (i);
4914 for (i = 0; i < n_basic_blocks; ++i)
4916 basic_block bb = BASIC_BLOCK (i);
4923 sbitmap_zero (blocks_out);
4925 /* We work through the queue until there are no more blocks. What
4926 is live at the end of this block is precisely the union of what
4927 is live at the beginning of all its successors. So, we set its
4928 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
4929 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
4930 this block by walking through the instructions in this block in
4931 reverse order and updating as we go. If that changed
4932 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
4933 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
4935 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
4936 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
4937 must either be live at the end of the block, or used within the
4938 block. In the latter case, it will certainly never disappear
4939 from GLOBAL_LIVE_AT_START. In the former case, the register
4940 could go away only if it disappeared from GLOBAL_LIVE_AT_START
4941 for one of the successor blocks. By induction, that cannot
4943 while (qhead != qtail)
4945 int rescan, changed;
4954 /* Begin by propagating live_at_start from the successor blocks. */
4955 CLEAR_REG_SET (new_live_at_end);
4956 for (e = bb->succ; e; e = e->succ_next)
4958 basic_block sb = e->dest;
4960 /* Call-clobbered registers die across exception and call edges. */
4961 /* ??? Abnormal call edges ignored for the moment, as this gets
4962 confused by sibling call edges, which crashes reg-stack. */
4963 if (e->flags & EDGE_EH)
4965 bitmap_operation (tmp, sb->global_live_at_start,
4966 call_used, BITMAP_AND_COMPL);
4967 IOR_REG_SET (new_live_at_end, tmp);
4970 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
4973 /* The all-important stack pointer must always be live. */
4974 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
4976 /* Before reload, there are a few registers that must be forced
4977 live everywhere -- which might not already be the case for
4978 blocks within infinite loops. */
4979 if (! reload_completed)
4981 /* Any reference to any pseudo before reload is a potential
4982 reference of the frame pointer. */
4983 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
4985 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4986 /* Pseudos with argument area equivalences may require
4987 reloading via the argument pointer. */
4988 if (fixed_regs[ARG_POINTER_REGNUM])
4989 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
4992 /* Any constant, or pseudo with constant equivalences, may
4993 require reloading from memory using the pic register. */
4994 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4995 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4996 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
4999 /* Regs used in phi nodes are not included in
5000 global_live_at_start, since they are live only along a
5001 particular edge. Set those regs that are live because of a
5002 phi node alternative corresponding to this particular block. */
5004 for_each_successor_phi (bb, &set_phi_alternative_reg,
5007 if (bb == ENTRY_BLOCK_PTR)
5009 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
5013 /* On our first pass through this block, we'll go ahead and continue.
5014 Recognize first pass by local_set NULL. On subsequent passes, we
5015 get to skip out early if live_at_end wouldn't have changed. */
5017 if (bb->local_set == NULL)
5019 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5020 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5025 /* If any bits were removed from live_at_end, we'll have to
5026 rescan the block. This wouldn't be necessary if we had
5027 precalculated local_live, however with PROP_SCAN_DEAD_CODE
5028 local_live is really dependent on live_at_end. */
5029 CLEAR_REG_SET (tmp);
5030 rescan = bitmap_operation (tmp, bb->global_live_at_end,
5031 new_live_at_end, BITMAP_AND_COMPL);
5035 /* If any of the registers in the new live_at_end set are
5036 conditionally set in this basic block, we must rescan.
5037 This is because conditional lifetimes at the end of the
5038 block do not just take the live_at_end set into account,
5039 but also the liveness at the start of each successor
5040 block. We can miss changes in those sets if we only
5041 compare the new live_at_end against the previous one. */
5042 CLEAR_REG_SET (tmp);
5043 rescan = bitmap_operation (tmp, new_live_at_end,
5044 bb->cond_local_set, BITMAP_AND);
5049 /* Find the set of changed bits. Take this opportunity
5050 to notice that this set is empty and early out. */
5051 CLEAR_REG_SET (tmp);
5052 changed = bitmap_operation (tmp, bb->global_live_at_end,
5053 new_live_at_end, BITMAP_XOR);
5057 /* If any of the changed bits overlap with local_set,
5058 we'll have to rescan the block. Detect overlap by
5059 the AND with ~local_set turning off bits. */
5060 rescan = bitmap_operation (tmp, tmp, bb->local_set,
5065 /* Let our caller know that BB changed enough to require its
5066 death notes updated. */
5068 SET_BIT (blocks_out, bb->index);
5072 /* Add to live_at_start the set of all registers in
5073 new_live_at_end that aren't in the old live_at_end. */
5075 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
5077 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
5079 changed = bitmap_operation (bb->global_live_at_start,
5080 bb->global_live_at_start,
5087 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
5089 /* Rescan the block insn by insn to turn (a copy of) live_at_end
5090 into live_at_start. */
5091 propagate_block (bb, new_live_at_end, bb->local_set,
5092 bb->cond_local_set, flags);
5094 /* If live_at start didn't change, no need to go farther. */
5095 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
5098 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
5101 /* Queue all predecessors of BB so that we may re-examine
5102 their live_at_end. */
5103 for (e = bb->pred; e; e = e->pred_next)
5105 basic_block pb = e->src;
5106 if (pb->aux == NULL)
5117 FREE_REG_SET (new_live_at_end);
5118 FREE_REG_SET (call_used);
5122 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
5124 basic_block bb = BASIC_BLOCK (i);
5125 FREE_REG_SET (bb->local_set);
5126 FREE_REG_SET (bb->cond_local_set);
5131 for (i = n_basic_blocks - 1; i >= 0; --i)
5133 basic_block bb = BASIC_BLOCK (i);
5134 FREE_REG_SET (bb->local_set);
5135 FREE_REG_SET (bb->cond_local_set);
5142 /* Subroutines of life analysis. */
5144 /* Allocate the permanent data structures that represent the results
5145 of life analysis. Not static since used also for stupid life analysis. */
5148 allocate_bb_life_data ()
5152 for (i = 0; i < n_basic_blocks; i++)
5154 basic_block bb = BASIC_BLOCK (i);
5156 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5157 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5160 ENTRY_BLOCK_PTR->global_live_at_end
5161 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5162 EXIT_BLOCK_PTR->global_live_at_start
5163 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5165 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
5169 allocate_reg_life_data ()
5173 max_regno = max_reg_num ();
5175 /* Recalculate the register space, in case it has grown. Old style
5176 vector oriented regsets would set regset_{size,bytes} here also. */
5177 allocate_reg_info (max_regno, FALSE, FALSE);
5179 /* Reset all the data we'll collect in propagate_block and its
5181 for (i = 0; i < max_regno; i++)
5185 REG_N_DEATHS (i) = 0;
5186 REG_N_CALLS_CROSSED (i) = 0;
5187 REG_LIVE_LENGTH (i) = 0;
5188 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
5192 /* Delete dead instructions for propagate_block. */
5195 propagate_block_delete_insn (bb, insn)
5199 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
5201 /* If the insn referred to a label, and that label was attached to
5202 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
5203 pretty much mandatory to delete it, because the ADDR_VEC may be
5204 referencing labels that no longer exist.
5206 INSN may reference a deleted label, particularly when a jump
5207 table has been optimized into a direct jump. There's no
5208 real good way to fix up the reference to the deleted label
5209 when the label is deleted, so we just allow it here.
5211 After dead code elimination is complete, we do search for
5212 any REG_LABEL notes which reference deleted labels as a
5215 if (inote && GET_CODE (inote) == CODE_LABEL)
5217 rtx label = XEXP (inote, 0);
5220 /* The label may be forced if it has been put in the constant
5221 pool. If that is the only use we must discard the table
5222 jump following it, but not the label itself. */
5223 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
5224 && (next = next_nonnote_insn (label)) != NULL
5225 && GET_CODE (next) == JUMP_INSN
5226 && (GET_CODE (PATTERN (next)) == ADDR_VEC
5227 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
5229 rtx pat = PATTERN (next);
5230 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
5231 int len = XVECLEN (pat, diff_vec_p);
5234 for (i = 0; i < len; i++)
5235 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
5237 flow_delete_insn (next);
5241 if (bb->end == insn)
5242 bb->end = PREV_INSN (insn);
5243 flow_delete_insn (insn);
5246 /* Delete dead libcalls for propagate_block. Return the insn
5247 before the libcall. */
5250 propagate_block_delete_libcall (bb, insn, note)
5254 rtx first = XEXP (note, 0);
5255 rtx before = PREV_INSN (first);
5257 if (insn == bb->end)
5260 flow_delete_insn_chain (first, insn);
5264 /* Update the life-status of regs for one insn. Return the previous insn. */
5267 propagate_one_insn (pbi, insn)
5268 struct propagate_block_info *pbi;
5271 rtx prev = PREV_INSN (insn);
5272 int flags = pbi->flags;
5273 int insn_is_dead = 0;
5274 int libcall_is_dead = 0;
5278 if (! INSN_P (insn))
5281 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
5282 if (flags & PROP_SCAN_DEAD_CODE)
5284 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
5285 libcall_is_dead = (insn_is_dead && note != 0
5286 && libcall_dead_p (pbi, note, insn));
5289 /* If an instruction consists of just dead store(s) on final pass,
5291 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
5293 /* If we're trying to delete a prologue or epilogue instruction
5294 that isn't flagged as possibly being dead, something is wrong.
5295 But if we are keeping the stack pointer depressed, we might well
5296 be deleting insns that are used to compute the amount to update
5297 it by, so they are fine. */
5298 if (reload_completed
5299 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
5300 && (TYPE_RETURNS_STACK_DEPRESSED
5301 (TREE_TYPE (current_function_decl))))
5302 && (((HAVE_epilogue || HAVE_prologue)
5303 && prologue_epilogue_contains (insn))
5304 || (HAVE_sibcall_epilogue
5305 && sibcall_epilogue_contains (insn)))
5306 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
5309 /* Record sets. Do this even for dead instructions, since they
5310 would have killed the values if they hadn't been deleted. */
5311 mark_set_regs (pbi, PATTERN (insn), insn);
5313 /* CC0 is now known to be dead. Either this insn used it,
5314 in which case it doesn't anymore, or clobbered it,
5315 so the next insn can't use it. */
5318 if (libcall_is_dead)
5319 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
5321 propagate_block_delete_insn (pbi->bb, insn);
5326 /* See if this is an increment or decrement that can be merged into
5327 a following memory address. */
5330 register rtx x = single_set (insn);
5332 /* Does this instruction increment or decrement a register? */
5333 if ((flags & PROP_AUTOINC)
5335 && GET_CODE (SET_DEST (x)) == REG
5336 && (GET_CODE (SET_SRC (x)) == PLUS
5337 || GET_CODE (SET_SRC (x)) == MINUS)
5338 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
5339 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
5340 /* Ok, look for a following memory ref we can combine with.
5341 If one is found, change the memory ref to a PRE_INC
5342 or PRE_DEC, cancel this insn, and return 1.
5343 Return 0 if nothing has been done. */
5344 && try_pre_increment_1 (pbi, insn))
5347 #endif /* AUTO_INC_DEC */
5349 CLEAR_REG_SET (pbi->new_set);
5351 /* If this is not the final pass, and this insn is copying the value of
5352 a library call and it's dead, don't scan the insns that perform the
5353 library call, so that the call's arguments are not marked live. */
5354 if (libcall_is_dead)
5356 /* Record the death of the dest reg. */
5357 mark_set_regs (pbi, PATTERN (insn), insn);
5359 insn = XEXP (note, 0);
5360 return PREV_INSN (insn);
5362 else if (GET_CODE (PATTERN (insn)) == SET
5363 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
5364 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
5365 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
5366 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
5367 /* We have an insn to pop a constant amount off the stack.
5368 (Such insns use PLUS regardless of the direction of the stack,
5369 and any insn to adjust the stack by a constant is always a pop.)
5370 These insns, if not dead stores, have no effect on life. */
5374 /* Any regs live at the time of a call instruction must not go
5375 in a register clobbered by calls. Find all regs now live and
5376 record this for them. */
5378 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
5379 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5380 { REG_N_CALLS_CROSSED (i)++; });
5382 /* Record sets. Do this even for dead instructions, since they
5383 would have killed the values if they hadn't been deleted. */
5384 mark_set_regs (pbi, PATTERN (insn), insn);
5386 if (GET_CODE (insn) == CALL_INSN)
5392 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5393 cond = COND_EXEC_TEST (PATTERN (insn));
5395 /* Non-constant calls clobber memory. */
5396 if (! CONST_OR_PURE_CALL_P (insn))
5398 free_EXPR_LIST_list (&pbi->mem_set_list);
5399 pbi->mem_set_list_len = 0;
5402 /* There may be extra registers to be clobbered. */
5403 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5405 note = XEXP (note, 1))
5406 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
5407 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
5408 cond, insn, pbi->flags);
5410 /* Calls change all call-used and global registers. */
5411 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5412 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
5414 /* We do not want REG_UNUSED notes for these registers. */
5415 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
5417 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
5421 /* If an insn doesn't use CC0, it becomes dead since we assume
5422 that every insn clobbers it. So show it dead here;
5423 mark_used_regs will set it live if it is referenced. */
5428 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
5430 /* Sometimes we may have inserted something before INSN (such as a move)
5431 when we make an auto-inc. So ensure we will scan those insns. */
5433 prev = PREV_INSN (insn);
5436 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
5442 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5443 cond = COND_EXEC_TEST (PATTERN (insn));
5445 /* Calls use their arguments. */
5446 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5448 note = XEXP (note, 1))
5449 if (GET_CODE (XEXP (note, 0)) == USE)
5450 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
5453 /* The stack ptr is used (honorarily) by a CALL insn. */
5454 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
5456 /* Calls may also reference any of the global registers,
5457 so they are made live. */
5458 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5460 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
5465 /* On final pass, update counts of how many insns in which each reg
5467 if (flags & PROP_REG_INFO)
5468 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5469 { REG_LIVE_LENGTH (i)++; });
5474 /* Initialize a propagate_block_info struct for public consumption.
5475 Note that the structure itself is opaque to this file, but that
5476 the user can use the regsets provided here. */
5478 struct propagate_block_info *
5479 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
5481 regset live, local_set, cond_local_set;
5484 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
5487 pbi->reg_live = live;
5488 pbi->mem_set_list = NULL_RTX;
5489 pbi->mem_set_list_len = 0;
5490 pbi->local_set = local_set;
5491 pbi->cond_local_set = cond_local_set;
5495 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5496 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
5498 pbi->reg_next_use = NULL;
5500 pbi->new_set = BITMAP_XMALLOC ();
5502 #ifdef HAVE_conditional_execution
5503 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
5504 free_reg_cond_life_info);
5505 pbi->reg_cond_reg = BITMAP_XMALLOC ();
5507 /* If this block ends in a conditional branch, for each register live
5508 from one side of the branch and not the other, record the register
5509 as conditionally dead. */
5510 if (GET_CODE (bb->end) == JUMP_INSN
5511 && any_condjump_p (bb->end))
5513 regset_head diff_head;
5514 regset diff = INITIALIZE_REG_SET (diff_head);
5515 basic_block bb_true, bb_false;
5516 rtx cond_true, cond_false, set_src;
5519 /* Identify the successor blocks. */
5520 bb_true = bb->succ->dest;
5521 if (bb->succ->succ_next != NULL)
5523 bb_false = bb->succ->succ_next->dest;
5525 if (bb->succ->flags & EDGE_FALLTHRU)
5527 basic_block t = bb_false;
5531 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
5536 /* This can happen with a conditional jump to the next insn. */
5537 if (JUMP_LABEL (bb->end) != bb_true->head)
5540 /* Simplest way to do nothing. */
5544 /* Extract the condition from the branch. */
5545 set_src = SET_SRC (pc_set (bb->end));
5546 cond_true = XEXP (set_src, 0);
5547 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
5548 GET_MODE (cond_true), XEXP (cond_true, 0),
5549 XEXP (cond_true, 1));
5550 if (GET_CODE (XEXP (set_src, 1)) == PC)
5553 cond_false = cond_true;
5557 /* Compute which register lead different lives in the successors. */
5558 if (bitmap_operation (diff, bb_true->global_live_at_start,
5559 bb_false->global_live_at_start, BITMAP_XOR))
5561 rtx reg = XEXP (cond_true, 0);
5563 if (GET_CODE (reg) == SUBREG)
5564 reg = SUBREG_REG (reg);
5566 if (GET_CODE (reg) != REG)
5569 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
5571 /* For each such register, mark it conditionally dead. */
5572 EXECUTE_IF_SET_IN_REG_SET
5575 struct reg_cond_life_info *rcli;
5578 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5580 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
5584 rcli->condition = cond;
5585 rcli->stores = const0_rtx;
5586 rcli->orig_condition = cond;
5588 splay_tree_insert (pbi->reg_cond_dead, i,
5589 (splay_tree_value) rcli);
5593 FREE_REG_SET (diff);
5597 /* If this block has no successors, any stores to the frame that aren't
5598 used later in the block are dead. So make a pass over the block
5599 recording any such that are made and show them dead at the end. We do
5600 a very conservative and simple job here. */
5602 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
5603 && (TYPE_RETURNS_STACK_DEPRESSED
5604 (TREE_TYPE (current_function_decl))))
5605 && (flags & PROP_SCAN_DEAD_CODE)
5606 && (bb->succ == NULL
5607 || (bb->succ->succ_next == NULL
5608 && bb->succ->dest == EXIT_BLOCK_PTR
5609 && ! current_function_calls_eh_return)))
5612 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
5613 if (GET_CODE (insn) == INSN
5614 && (set = single_set (insn))
5615 && GET_CODE (SET_DEST (set)) == MEM)
5617 rtx mem = SET_DEST (set);
5618 rtx canon_mem = canon_rtx (mem);
5620 /* This optimization is performed by faking a store to the
5621 memory at the end of the block. This doesn't work for
5622 unchanging memories because multiple stores to unchanging
5623 memory is illegal and alias analysis doesn't consider it. */
5624 if (RTX_UNCHANGING_P (canon_mem))
5627 if (XEXP (canon_mem, 0) == frame_pointer_rtx
5628 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
5629 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
5630 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
5631 add_to_mem_set_list (pbi, canon_mem);
5638 /* Release a propagate_block_info struct. */
5641 free_propagate_block_info (pbi)
5642 struct propagate_block_info *pbi;
5644 free_EXPR_LIST_list (&pbi->mem_set_list);
5646 BITMAP_XFREE (pbi->new_set);
5648 #ifdef HAVE_conditional_execution
5649 splay_tree_delete (pbi->reg_cond_dead);
5650 BITMAP_XFREE (pbi->reg_cond_reg);
5653 if (pbi->reg_next_use)
5654 free (pbi->reg_next_use);
5659 /* Compute the registers live at the beginning of a basic block BB from
5660 those live at the end.
5662 When called, REG_LIVE contains those live at the end. On return, it
5663 contains those live at the beginning.
5665 LOCAL_SET, if non-null, will be set with all registers killed
5666 unconditionally by this basic block.
5667 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
5668 killed conditionally by this basic block. If there is any unconditional
5669 set of a register, then the corresponding bit will be set in LOCAL_SET
5670 and cleared in COND_LOCAL_SET.
5671 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
5672 case, the resulting set will be equal to the union of the two sets that
5673 would otherwise be computed.
5675 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
5678 propagate_block (bb, live, local_set, cond_local_set, flags)
5682 regset cond_local_set;
5685 struct propagate_block_info *pbi;
5689 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
5691 if (flags & PROP_REG_INFO)
5695 /* Process the regs live at the end of the block.
5696 Mark them as not local to any one basic block. */
5697 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
5698 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
5701 /* Scan the block an insn at a time from end to beginning. */
5704 for (insn = bb->end;; insn = prev)
5706 /* If this is a call to `setjmp' et al, warn if any
5707 non-volatile datum is live. */
5708 if ((flags & PROP_REG_INFO)
5709 && GET_CODE (insn) == NOTE
5710 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
5711 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
5713 prev = propagate_one_insn (pbi, insn);
5714 changed |= NEXT_INSN (prev) != insn;
5716 if (insn == bb->head)
5720 free_propagate_block_info (pbi);
5725 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
5726 (SET expressions whose destinations are registers dead after the insn).
5727 NEEDED is the regset that says which regs are alive after the insn.
5729 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
5731 If X is the entire body of an insn, NOTES contains the reg notes
5732 pertaining to the insn. */
5735 insn_dead_p (pbi, x, call_ok, notes)
5736 struct propagate_block_info *pbi;
5739 rtx notes ATTRIBUTE_UNUSED;
5741 enum rtx_code code = GET_CODE (x);
5744 /* If flow is invoked after reload, we must take existing AUTO_INC
5745 expresions into account. */
5746 if (reload_completed)
5748 for (; notes; notes = XEXP (notes, 1))
5750 if (REG_NOTE_KIND (notes) == REG_INC)
5752 int regno = REGNO (XEXP (notes, 0));
5754 /* Don't delete insns to set global regs. */
5755 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5756 || REGNO_REG_SET_P (pbi->reg_live, regno))
5763 /* If setting something that's a reg or part of one,
5764 see if that register's altered value will be live. */
5768 rtx r = SET_DEST (x);
5771 if (GET_CODE (r) == CC0)
5772 return ! pbi->cc0_live;
5775 /* A SET that is a subroutine call cannot be dead. */
5776 if (GET_CODE (SET_SRC (x)) == CALL)
5782 /* Don't eliminate loads from volatile memory or volatile asms. */
5783 else if (volatile_refs_p (SET_SRC (x)))
5786 if (GET_CODE (r) == MEM)
5790 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
5793 canon_r = canon_rtx (r);
5795 /* Walk the set of memory locations we are currently tracking
5796 and see if one is an identical match to this memory location.
5797 If so, this memory write is dead (remember, we're walking
5798 backwards from the end of the block to the start). Since
5799 rtx_equal_p does not check the alias set or flags, we also
5800 must have the potential for them to conflict (anti_dependence). */
5801 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
5802 if (anti_dependence (r, XEXP (temp, 0)))
5804 rtx mem = XEXP (temp, 0);
5806 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
5807 && (GET_MODE_SIZE (GET_MODE (canon_r))
5808 <= GET_MODE_SIZE (GET_MODE (mem))))
5812 /* Check if memory reference matches an auto increment. Only
5813 post increment/decrement or modify are valid. */
5814 if (GET_MODE (mem) == GET_MODE (r)
5815 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
5816 || GET_CODE (XEXP (mem, 0)) == POST_INC
5817 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
5818 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
5819 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
5826 while (GET_CODE (r) == SUBREG
5827 || GET_CODE (r) == STRICT_LOW_PART
5828 || GET_CODE (r) == ZERO_EXTRACT)
5831 if (GET_CODE (r) == REG)
5833 int regno = REGNO (r);
5836 if (REGNO_REG_SET_P (pbi->reg_live, regno))
5839 /* If this is a hard register, verify that subsequent
5840 words are not needed. */
5841 if (regno < FIRST_PSEUDO_REGISTER)
5843 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
5846 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
5850 /* Don't delete insns to set global regs. */
5851 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5854 /* Make sure insns to set the stack pointer aren't deleted. */
5855 if (regno == STACK_POINTER_REGNUM)
5858 /* ??? These bits might be redundant with the force live bits
5859 in calculate_global_regs_live. We would delete from
5860 sequential sets; whether this actually affects real code
5861 for anything but the stack pointer I don't know. */
5862 /* Make sure insns to set the frame pointer aren't deleted. */
5863 if (regno == FRAME_POINTER_REGNUM
5864 && (! reload_completed || frame_pointer_needed))
5866 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5867 if (regno == HARD_FRAME_POINTER_REGNUM
5868 && (! reload_completed || frame_pointer_needed))
5872 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5873 /* Make sure insns to set arg pointer are never deleted
5874 (if the arg pointer isn't fixed, there will be a USE
5875 for it, so we can treat it normally). */
5876 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5880 /* Otherwise, the set is dead. */
5886 /* If performing several activities, insn is dead if each activity
5887 is individually dead. Also, CLOBBERs and USEs can be ignored; a
5888 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
5890 else if (code == PARALLEL)
5892 int i = XVECLEN (x, 0);
5894 for (i--; i >= 0; i--)
5895 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
5896 && GET_CODE (XVECEXP (x, 0, i)) != USE
5897 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
5903 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
5904 is not necessarily true for hard registers. */
5905 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
5906 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
5907 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
5910 /* We do not check other CLOBBER or USE here. An insn consisting of just
5911 a CLOBBER or just a USE should not be deleted. */
5915 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
5916 return 1 if the entire library call is dead.
5917 This is true if INSN copies a register (hard or pseudo)
5918 and if the hard return reg of the call insn is dead.
5919 (The caller should have tested the destination of the SET inside
5920 INSN already for death.)
5922 If this insn doesn't just copy a register, then we don't
5923 have an ordinary libcall. In that case, cse could not have
5924 managed to substitute the source for the dest later on,
5925 so we can assume the libcall is dead.
5927 PBI is the block info giving pseudoregs live before this insn.
5928 NOTE is the REG_RETVAL note of the insn. */
5931 libcall_dead_p (pbi, note, insn)
5932 struct propagate_block_info *pbi;
5936 rtx x = single_set (insn);
5940 register rtx r = SET_SRC (x);
5941 if (GET_CODE (r) == REG)
5943 rtx call = XEXP (note, 0);
5947 /* Find the call insn. */
5948 while (call != insn && GET_CODE (call) != CALL_INSN)
5949 call = NEXT_INSN (call);
5951 /* If there is none, do nothing special,
5952 since ordinary death handling can understand these insns. */
5956 /* See if the hard reg holding the value is dead.
5957 If this is a PARALLEL, find the call within it. */
5958 call_pat = PATTERN (call);
5959 if (GET_CODE (call_pat) == PARALLEL)
5961 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
5962 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
5963 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
5966 /* This may be a library call that is returning a value
5967 via invisible pointer. Do nothing special, since
5968 ordinary death handling can understand these insns. */
5972 call_pat = XVECEXP (call_pat, 0, i);
5975 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
5981 /* Return 1 if register REGNO was used before it was set, i.e. if it is
5982 live at function entry. Don't count global register variables, variables
5983 in registers that can be used for function arg passing, or variables in
5984 fixed hard registers. */
5987 regno_uninitialized (regno)
5990 if (n_basic_blocks == 0
5991 || (regno < FIRST_PSEUDO_REGISTER
5992 && (global_regs[regno]
5993 || fixed_regs[regno]
5994 || FUNCTION_ARG_REGNO_P (regno))))
5997 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
6000 /* 1 if register REGNO was alive at a place where `setjmp' was called
6001 and was set more than once or is an argument.
6002 Such regs may be clobbered by `longjmp'. */
6005 regno_clobbered_at_setjmp (regno)
6008 if (n_basic_blocks == 0)
6011 return ((REG_N_SETS (regno) > 1
6012 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
6013 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
6016 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
6017 maximal list size; look for overlaps in mode and select the largest. */
6019 add_to_mem_set_list (pbi, mem)
6020 struct propagate_block_info *pbi;
6025 /* We don't know how large a BLKmode store is, so we must not
6026 take them into consideration. */
6027 if (GET_MODE (mem) == BLKmode)
6030 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
6032 rtx e = XEXP (i, 0);
6033 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
6035 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
6038 /* If we must store a copy of the mem, we can just modify
6039 the mode of the stored copy. */
6040 if (pbi->flags & PROP_AUTOINC)
6041 PUT_MODE (e, GET_MODE (mem));
6050 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
6053 /* Store a copy of mem, otherwise the address may be
6054 scrogged by find_auto_inc. */
6055 if (pbi->flags & PROP_AUTOINC)
6056 mem = shallow_copy_rtx (mem);
6058 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
6059 pbi->mem_set_list_len++;
6063 /* INSN references memory, possibly using autoincrement addressing modes.
6064 Find any entries on the mem_set_list that need to be invalidated due
6065 to an address change. */
6068 invalidate_mems_from_autoinc (pbi, insn)
6069 struct propagate_block_info *pbi;
6072 rtx note = REG_NOTES (insn);
6073 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
6074 if (REG_NOTE_KIND (note) == REG_INC)
6075 invalidate_mems_from_set (pbi, XEXP (note, 0));
6078 /* EXP is a REG. Remove any dependant entries from pbi->mem_set_list. */
6081 invalidate_mems_from_set (pbi, exp)
6082 struct propagate_block_info *pbi;
6085 rtx temp = pbi->mem_set_list;
6086 rtx prev = NULL_RTX;
6091 next = XEXP (temp, 1);
6092 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
6094 /* Splice this entry out of the list. */
6096 XEXP (prev, 1) = next;
6098 pbi->mem_set_list = next;
6099 free_EXPR_LIST_node (temp);
6100 pbi->mem_set_list_len--;
6108 /* Process the registers that are set within X. Their bits are set to
6109 1 in the regset DEAD, because they are dead prior to this insn.
6111 If INSN is nonzero, it is the insn being processed.
6113 FLAGS is the set of operations to perform. */
6116 mark_set_regs (pbi, x, insn)
6117 struct propagate_block_info *pbi;
6120 rtx cond = NULL_RTX;
6125 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
6127 if (REG_NOTE_KIND (link) == REG_INC)
6128 mark_set_1 (pbi, SET, XEXP (link, 0),
6129 (GET_CODE (x) == COND_EXEC
6130 ? COND_EXEC_TEST (x) : NULL_RTX),
6134 switch (code = GET_CODE (x))
6138 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
6142 cond = COND_EXEC_TEST (x);
6143 x = COND_EXEC_CODE (x);
6149 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
6151 rtx sub = XVECEXP (x, 0, i);
6152 switch (code = GET_CODE (sub))
6155 if (cond != NULL_RTX)
6158 cond = COND_EXEC_TEST (sub);
6159 sub = COND_EXEC_CODE (sub);
6160 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
6166 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
6181 /* Process a single set, which appears in INSN. REG (which may not
6182 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
6183 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
6184 If the set is conditional (because it appear in a COND_EXEC), COND
6185 will be the condition. */
6188 mark_set_1 (pbi, code, reg, cond, insn, flags)
6189 struct propagate_block_info *pbi;
6191 rtx reg, cond, insn;
6194 int regno_first = -1, regno_last = -1;
6195 unsigned long not_dead = 0;
6198 /* Modifying just one hardware register of a multi-reg value or just a
6199 byte field of a register does not mean the value from before this insn
6200 is now dead. Of course, if it was dead after it's unused now. */
6202 switch (GET_CODE (reg))
6205 /* Some targets place small structures in registers for return values of
6206 functions. We have to detect this case specially here to get correct
6207 flow information. */
6208 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
6209 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
6210 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
6216 case STRICT_LOW_PART:
6217 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
6219 reg = XEXP (reg, 0);
6220 while (GET_CODE (reg) == SUBREG
6221 || GET_CODE (reg) == ZERO_EXTRACT
6222 || GET_CODE (reg) == SIGN_EXTRACT
6223 || GET_CODE (reg) == STRICT_LOW_PART);
6224 if (GET_CODE (reg) == MEM)
6226 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
6230 regno_last = regno_first = REGNO (reg);
6231 if (regno_first < FIRST_PSEUDO_REGISTER)
6232 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
6236 if (GET_CODE (SUBREG_REG (reg)) == REG)
6238 enum machine_mode outer_mode = GET_MODE (reg);
6239 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
6241 /* Identify the range of registers affected. This is moderately
6242 tricky for hard registers. See alter_subreg. */
6244 regno_last = regno_first = REGNO (SUBREG_REG (reg));
6245 if (regno_first < FIRST_PSEUDO_REGISTER)
6247 regno_first += subreg_regno_offset (regno_first, inner_mode,
6250 regno_last = (regno_first
6251 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
6253 /* Since we've just adjusted the register number ranges, make
6254 sure REG matches. Otherwise some_was_live will be clear
6255 when it shouldn't have been, and we'll create incorrect
6256 REG_UNUSED notes. */
6257 reg = gen_rtx_REG (outer_mode, regno_first);
6261 /* If the number of words in the subreg is less than the number
6262 of words in the full register, we have a well-defined partial
6263 set. Otherwise the high bits are undefined.
6265 This is only really applicable to pseudos, since we just took
6266 care of multi-word hard registers. */
6267 if (((GET_MODE_SIZE (outer_mode)
6268 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
6269 < ((GET_MODE_SIZE (inner_mode)
6270 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
6271 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
6274 reg = SUBREG_REG (reg);
6278 reg = SUBREG_REG (reg);
6285 /* If this set is a MEM, then it kills any aliased writes.
6286 If this set is a REG, then it kills any MEMs which use the reg. */
6287 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
6289 if (GET_CODE (reg) == REG)
6290 invalidate_mems_from_set (pbi, reg);
6292 /* If the memory reference had embedded side effects (autoincrement
6293 address modes. Then we may need to kill some entries on the
6295 if (insn && GET_CODE (reg) == MEM)
6296 invalidate_mems_from_autoinc (pbi, insn);
6298 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
6299 /* ??? With more effort we could track conditional memory life. */
6301 /* There are no REG_INC notes for SP, so we can't assume we'll see
6302 everything that invalidates it. To be safe, don't eliminate any
6303 stores though SP; none of them should be redundant anyway. */
6304 && ! reg_mentioned_p (stack_pointer_rtx, reg))
6305 add_to_mem_set_list (pbi, canon_rtx (reg));
6308 if (GET_CODE (reg) == REG
6309 && ! (regno_first == FRAME_POINTER_REGNUM
6310 && (! reload_completed || frame_pointer_needed))
6311 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
6312 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
6313 && (! reload_completed || frame_pointer_needed))
6315 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
6316 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
6320 int some_was_live = 0, some_was_dead = 0;
6322 for (i = regno_first; i <= regno_last; ++i)
6324 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
6327 /* Order of the set operation matters here since both
6328 sets may be the same. */
6329 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
6330 if (cond != NULL_RTX
6331 && ! REGNO_REG_SET_P (pbi->local_set, i))
6332 SET_REGNO_REG_SET (pbi->cond_local_set, i);
6334 SET_REGNO_REG_SET (pbi->local_set, i);
6336 if (code != CLOBBER)
6337 SET_REGNO_REG_SET (pbi->new_set, i);
6339 some_was_live |= needed_regno;
6340 some_was_dead |= ! needed_regno;
6343 #ifdef HAVE_conditional_execution
6344 /* Consider conditional death in deciding that the register needs
6346 if (some_was_live && ! not_dead
6347 /* The stack pointer is never dead. Well, not strictly true,
6348 but it's very difficult to tell from here. Hopefully
6349 combine_stack_adjustments will fix up the most egregious
6351 && regno_first != STACK_POINTER_REGNUM)
6353 for (i = regno_first; i <= regno_last; ++i)
6354 if (! mark_regno_cond_dead (pbi, i, cond))
6355 not_dead |= ((unsigned long) 1) << (i - regno_first);
6359 /* Additional data to record if this is the final pass. */
6360 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
6361 | PROP_DEATH_NOTES | PROP_AUTOINC))
6364 register int blocknum = pbi->bb->index;
6367 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6369 y = pbi->reg_next_use[regno_first];
6371 /* The next use is no longer next, since a store intervenes. */
6372 for (i = regno_first; i <= regno_last; ++i)
6373 pbi->reg_next_use[i] = 0;
6376 if (flags & PROP_REG_INFO)
6378 for (i = regno_first; i <= regno_last; ++i)
6380 /* Count (weighted) references, stores, etc. This counts a
6381 register twice if it is modified, but that is correct. */
6382 REG_N_SETS (i) += 1;
6383 REG_N_REFS (i) += 1;
6384 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
6386 /* The insns where a reg is live are normally counted
6387 elsewhere, but we want the count to include the insn
6388 where the reg is set, and the normal counting mechanism
6389 would not count it. */
6390 REG_LIVE_LENGTH (i) += 1;
6393 /* If this is a hard reg, record this function uses the reg. */
6394 if (regno_first < FIRST_PSEUDO_REGISTER)
6396 for (i = regno_first; i <= regno_last; i++)
6397 regs_ever_live[i] = 1;
6401 /* Keep track of which basic blocks each reg appears in. */
6402 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6403 REG_BASIC_BLOCK (regno_first) = blocknum;
6404 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6405 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6409 if (! some_was_dead)
6411 if (flags & PROP_LOG_LINKS)
6413 /* Make a logical link from the next following insn
6414 that uses this register, back to this insn.
6415 The following insns have already been processed.
6417 We don't build a LOG_LINK for hard registers containing
6418 in ASM_OPERANDs. If these registers get replaced,
6419 we might wind up changing the semantics of the insn,
6420 even if reload can make what appear to be valid
6421 assignments later. */
6422 if (y && (BLOCK_NUM (y) == blocknum)
6423 && (regno_first >= FIRST_PSEUDO_REGISTER
6424 || asm_noperands (PATTERN (y)) < 0))
6425 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
6430 else if (! some_was_live)
6432 if (flags & PROP_REG_INFO)
6433 REG_N_DEATHS (regno_first) += 1;
6435 if (flags & PROP_DEATH_NOTES)
6437 /* Note that dead stores have already been deleted
6438 when possible. If we get here, we have found a
6439 dead store that cannot be eliminated (because the
6440 same insn does something useful). Indicate this
6441 by marking the reg being set as dying here. */
6443 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6448 if (flags & PROP_DEATH_NOTES)
6450 /* This is a case where we have a multi-word hard register
6451 and some, but not all, of the words of the register are
6452 needed in subsequent insns. Write REG_UNUSED notes
6453 for those parts that were not needed. This case should
6456 for (i = regno_first; i <= regno_last; ++i)
6457 if (! REGNO_REG_SET_P (pbi->reg_live, i))
6459 = alloc_EXPR_LIST (REG_UNUSED,
6460 gen_rtx_REG (reg_raw_mode[i], i),
6466 /* Mark the register as being dead. */
6468 /* The stack pointer is never dead. Well, not strictly true,
6469 but it's very difficult to tell from here. Hopefully
6470 combine_stack_adjustments will fix up the most egregious
6472 && regno_first != STACK_POINTER_REGNUM)
6474 for (i = regno_first; i <= regno_last; ++i)
6475 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
6476 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
6479 else if (GET_CODE (reg) == REG)
6481 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6482 pbi->reg_next_use[regno_first] = 0;
6485 /* If this is the last pass and this is a SCRATCH, show it will be dying
6486 here and count it. */
6487 else if (GET_CODE (reg) == SCRATCH)
6489 if (flags & PROP_DEATH_NOTES)
6491 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6495 #ifdef HAVE_conditional_execution
6496 /* Mark REGNO conditionally dead.
6497 Return true if the register is now unconditionally dead. */
6500 mark_regno_cond_dead (pbi, regno, cond)
6501 struct propagate_block_info *pbi;
6505 /* If this is a store to a predicate register, the value of the
6506 predicate is changing, we don't know that the predicate as seen
6507 before is the same as that seen after. Flush all dependent
6508 conditions from reg_cond_dead. This will make all such
6509 conditionally live registers unconditionally live. */
6510 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
6511 flush_reg_cond_reg (pbi, regno);
6513 /* If this is an unconditional store, remove any conditional
6514 life that may have existed. */
6515 if (cond == NULL_RTX)
6516 splay_tree_remove (pbi->reg_cond_dead, regno);
6519 splay_tree_node node;
6520 struct reg_cond_life_info *rcli;
6523 /* Otherwise this is a conditional set. Record that fact.
6524 It may have been conditionally used, or there may be a
6525 subsequent set with a complimentary condition. */
6527 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
6530 /* The register was unconditionally live previously.
6531 Record the current condition as the condition under
6532 which it is dead. */
6533 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6534 rcli->condition = cond;
6535 rcli->stores = cond;
6536 rcli->orig_condition = const0_rtx;
6537 splay_tree_insert (pbi->reg_cond_dead, regno,
6538 (splay_tree_value) rcli);
6540 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6542 /* Not unconditionaly dead. */
6547 /* The register was conditionally live previously.
6548 Add the new condition to the old. */
6549 rcli = (struct reg_cond_life_info *) node->value;
6550 ncond = rcli->condition;
6551 ncond = ior_reg_cond (ncond, cond, 1);
6552 if (rcli->stores == const0_rtx)
6553 rcli->stores = cond;
6554 else if (rcli->stores != const1_rtx)
6555 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
6557 /* If the register is now unconditionally dead, remove the entry
6558 in the splay_tree. A register is unconditionally dead if the
6559 dead condition ncond is true. A register is also unconditionally
6560 dead if the sum of all conditional stores is an unconditional
6561 store (stores is true), and the dead condition is identically the
6562 same as the original dead condition initialized at the end of
6563 the block. This is a pointer compare, not an rtx_equal_p
6565 if (ncond == const1_rtx
6566 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
6567 splay_tree_remove (pbi->reg_cond_dead, regno);
6570 rcli->condition = ncond;
6572 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6574 /* Not unconditionaly dead. */
6583 /* Called from splay_tree_delete for pbi->reg_cond_life. */
6586 free_reg_cond_life_info (value)
6587 splay_tree_value value;
6589 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
6593 /* Helper function for flush_reg_cond_reg. */
6596 flush_reg_cond_reg_1 (node, data)
6597 splay_tree_node node;
6600 struct reg_cond_life_info *rcli;
6601 int *xdata = (int *) data;
6602 unsigned int regno = xdata[0];
6604 /* Don't need to search if last flushed value was farther on in
6605 the in-order traversal. */
6606 if (xdata[1] >= (int) node->key)
6609 /* Splice out portions of the expression that refer to regno. */
6610 rcli = (struct reg_cond_life_info *) node->value;
6611 rcli->condition = elim_reg_cond (rcli->condition, regno);
6612 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
6613 rcli->stores = elim_reg_cond (rcli->stores, regno);
6615 /* If the entire condition is now false, signal the node to be removed. */
6616 if (rcli->condition == const0_rtx)
6618 xdata[1] = node->key;
6621 else if (rcli->condition == const1_rtx)
6627 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
6630 flush_reg_cond_reg (pbi, regno)
6631 struct propagate_block_info *pbi;
6638 while (splay_tree_foreach (pbi->reg_cond_dead,
6639 flush_reg_cond_reg_1, pair) == -1)
6640 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
6642 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
6645 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
6646 For ior/and, the ADD flag determines whether we want to add the new
6647 condition X to the old one unconditionally. If it is zero, we will
6648 only return a new expression if X allows us to simplify part of
6649 OLD, otherwise we return OLD unchanged to the caller.
6650 If ADD is nonzero, we will return a new condition in all cases. The
6651 toplevel caller of one of these functions should always pass 1 for
6655 ior_reg_cond (old, x, add)
6661 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6663 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6664 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
6665 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6667 if (GET_CODE (x) == GET_CODE (old)
6668 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6672 return gen_rtx_IOR (0, old, x);
6675 switch (GET_CODE (old))
6678 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6679 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6680 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6682 if (op0 == const0_rtx)
6684 if (op1 == const0_rtx)
6686 if (op0 == const1_rtx || op1 == const1_rtx)
6688 if (op0 == XEXP (old, 0))
6689 op0 = gen_rtx_IOR (0, op0, x);
6691 op1 = gen_rtx_IOR (0, op1, x);
6692 return gen_rtx_IOR (0, op0, op1);
6696 return gen_rtx_IOR (0, old, x);
6699 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6700 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6701 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6703 if (op0 == const1_rtx)
6705 if (op1 == const1_rtx)
6707 if (op0 == const0_rtx || op1 == const0_rtx)
6709 if (op0 == XEXP (old, 0))
6710 op0 = gen_rtx_IOR (0, op0, x);
6712 op1 = gen_rtx_IOR (0, op1, x);
6713 return gen_rtx_AND (0, op0, op1);
6717 return gen_rtx_IOR (0, old, x);
6720 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6721 if (op0 != XEXP (old, 0))
6722 return not_reg_cond (op0);
6725 return gen_rtx_IOR (0, old, x);
6736 enum rtx_code x_code;
6738 if (x == const0_rtx)
6740 else if (x == const1_rtx)
6742 x_code = GET_CODE (x);
6745 if (GET_RTX_CLASS (x_code) == '<'
6746 && GET_CODE (XEXP (x, 0)) == REG)
6748 if (XEXP (x, 1) != const0_rtx)
6751 return gen_rtx_fmt_ee (reverse_condition (x_code),
6752 VOIDmode, XEXP (x, 0), const0_rtx);
6754 return gen_rtx_NOT (0, x);
6758 and_reg_cond (old, x, add)
6764 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6766 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6767 && GET_CODE (x) == reverse_condition (GET_CODE (old))
6768 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6770 if (GET_CODE (x) == GET_CODE (old)
6771 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6775 return gen_rtx_AND (0, old, x);
6778 switch (GET_CODE (old))
6781 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6782 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6783 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6785 if (op0 == const0_rtx)
6787 if (op1 == const0_rtx)
6789 if (op0 == const1_rtx || op1 == const1_rtx)
6791 if (op0 == XEXP (old, 0))
6792 op0 = gen_rtx_AND (0, op0, x);
6794 op1 = gen_rtx_AND (0, op1, x);
6795 return gen_rtx_IOR (0, op0, op1);
6799 return gen_rtx_AND (0, old, x);
6802 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6803 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6804 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6806 if (op0 == const1_rtx)
6808 if (op1 == const1_rtx)
6810 if (op0 == const0_rtx || op1 == const0_rtx)
6812 if (op0 == XEXP (old, 0))
6813 op0 = gen_rtx_AND (0, op0, x);
6815 op1 = gen_rtx_AND (0, op1, x);
6816 return gen_rtx_AND (0, op0, op1);
6821 /* If X is identical to one of the existing terms of the AND,
6822 then just return what we already have. */
6823 /* ??? There really should be some sort of recursive check here in
6824 case there are nested ANDs. */
6825 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
6826 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
6827 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
6828 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
6831 return gen_rtx_AND (0, old, x);
6834 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6835 if (op0 != XEXP (old, 0))
6836 return not_reg_cond (op0);
6839 return gen_rtx_AND (0, old, x);
6846 /* Given a condition X, remove references to reg REGNO and return the
6847 new condition. The removal will be done so that all conditions
6848 involving REGNO are considered to evaluate to false. This function
6849 is used when the value of REGNO changes. */
6852 elim_reg_cond (x, regno)
6858 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
6860 if (REGNO (XEXP (x, 0)) == regno)
6865 switch (GET_CODE (x))
6868 op0 = elim_reg_cond (XEXP (x, 0), regno);
6869 op1 = elim_reg_cond (XEXP (x, 1), regno);
6870 if (op0 == const0_rtx || op1 == const0_rtx)
6872 if (op0 == const1_rtx)
6874 if (op1 == const1_rtx)
6876 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6878 return gen_rtx_AND (0, op0, op1);
6881 op0 = elim_reg_cond (XEXP (x, 0), regno);
6882 op1 = elim_reg_cond (XEXP (x, 1), regno);
6883 if (op0 == const1_rtx || op1 == const1_rtx)
6885 if (op0 == const0_rtx)
6887 if (op1 == const0_rtx)
6889 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6891 return gen_rtx_IOR (0, op0, op1);
6894 op0 = elim_reg_cond (XEXP (x, 0), regno);
6895 if (op0 == const0_rtx)
6897 if (op0 == const1_rtx)
6899 if (op0 != XEXP (x, 0))
6900 return not_reg_cond (op0);
6907 #endif /* HAVE_conditional_execution */
6911 /* Try to substitute the auto-inc expression INC as the address inside
6912 MEM which occurs in INSN. Currently, the address of MEM is an expression
6913 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
6914 that has a single set whose source is a PLUS of INCR_REG and something
6918 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
6919 struct propagate_block_info *pbi;
6920 rtx inc, insn, mem, incr, incr_reg;
6922 int regno = REGNO (incr_reg);
6923 rtx set = single_set (incr);
6924 rtx q = SET_DEST (set);
6925 rtx y = SET_SRC (set);
6926 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
6928 /* Make sure this reg appears only once in this insn. */
6929 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
6932 if (dead_or_set_p (incr, incr_reg)
6933 /* Mustn't autoinc an eliminable register. */
6934 && (regno >= FIRST_PSEUDO_REGISTER
6935 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
6937 /* This is the simple case. Try to make the auto-inc. If
6938 we can't, we are done. Otherwise, we will do any
6939 needed updates below. */
6940 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
6943 else if (GET_CODE (q) == REG
6944 /* PREV_INSN used here to check the semi-open interval
6946 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
6947 /* We must also check for sets of q as q may be
6948 a call clobbered hard register and there may
6949 be a call between PREV_INSN (insn) and incr. */
6950 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
6952 /* We have *p followed sometime later by q = p+size.
6953 Both p and q must be live afterward,
6954 and q is not used between INSN and its assignment.
6955 Change it to q = p, ...*q..., q = q+size.
6956 Then fall into the usual case. */
6960 emit_move_insn (q, incr_reg);
6961 insns = get_insns ();
6964 if (basic_block_for_insn)
6965 for (temp = insns; temp; temp = NEXT_INSN (temp))
6966 set_block_for_insn (temp, pbi->bb);
6968 /* If we can't make the auto-inc, or can't make the
6969 replacement into Y, exit. There's no point in making
6970 the change below if we can't do the auto-inc and doing
6971 so is not correct in the pre-inc case. */
6974 validate_change (insn, &XEXP (mem, 0), inc, 1);
6975 validate_change (incr, &XEXP (y, opnum), q, 1);
6976 if (! apply_change_group ())
6979 /* We now know we'll be doing this change, so emit the
6980 new insn(s) and do the updates. */
6981 emit_insns_before (insns, insn);
6983 if (pbi->bb->head == insn)
6984 pbi->bb->head = insns;
6986 /* INCR will become a NOTE and INSN won't contain a
6987 use of INCR_REG. If a use of INCR_REG was just placed in
6988 the insn before INSN, make that the next use.
6989 Otherwise, invalidate it. */
6990 if (GET_CODE (PREV_INSN (insn)) == INSN
6991 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
6992 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
6993 pbi->reg_next_use[regno] = PREV_INSN (insn);
6995 pbi->reg_next_use[regno] = 0;
7000 /* REGNO is now used in INCR which is below INSN, but
7001 it previously wasn't live here. If we don't mark
7002 it as live, we'll put a REG_DEAD note for it
7003 on this insn, which is incorrect. */
7004 SET_REGNO_REG_SET (pbi->reg_live, regno);
7006 /* If there are any calls between INSN and INCR, show
7007 that REGNO now crosses them. */
7008 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
7009 if (GET_CODE (temp) == CALL_INSN)
7010 REG_N_CALLS_CROSSED (regno)++;
7015 /* If we haven't returned, it means we were able to make the
7016 auto-inc, so update the status. First, record that this insn
7017 has an implicit side effect. */
7019 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
7021 /* Modify the old increment-insn to simply copy
7022 the already-incremented value of our register. */
7023 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
7026 /* If that makes it a no-op (copying the register into itself) delete
7027 it so it won't appear to be a "use" and a "set" of this
7029 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
7031 /* If the original source was dead, it's dead now. */
7034 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
7036 remove_note (incr, note);
7037 if (XEXP (note, 0) != incr_reg)
7038 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
7041 PUT_CODE (incr, NOTE);
7042 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
7043 NOTE_SOURCE_FILE (incr) = 0;
7046 if (regno >= FIRST_PSEUDO_REGISTER)
7048 /* Count an extra reference to the reg. When a reg is
7049 incremented, spilling it is worse, so we want to make
7050 that less likely. */
7051 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
7053 /* Count the increment as a setting of the register,
7054 even though it isn't a SET in rtl. */
7055 REG_N_SETS (regno)++;
7059 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
7063 find_auto_inc (pbi, x, insn)
7064 struct propagate_block_info *pbi;
7068 rtx addr = XEXP (x, 0);
7069 HOST_WIDE_INT offset = 0;
7070 rtx set, y, incr, inc_val;
7072 int size = GET_MODE_SIZE (GET_MODE (x));
7074 if (GET_CODE (insn) == JUMP_INSN)
7077 /* Here we detect use of an index register which might be good for
7078 postincrement, postdecrement, preincrement, or predecrement. */
7080 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
7081 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
7083 if (GET_CODE (addr) != REG)
7086 regno = REGNO (addr);
7088 /* Is the next use an increment that might make auto-increment? */
7089 incr = pbi->reg_next_use[regno];
7090 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
7092 set = single_set (incr);
7093 if (set == 0 || GET_CODE (set) != SET)
7097 if (GET_CODE (y) != PLUS)
7100 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
7101 inc_val = XEXP (y, 1);
7102 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
7103 inc_val = XEXP (y, 0);
7107 if (GET_CODE (inc_val) == CONST_INT)
7109 if (HAVE_POST_INCREMENT
7110 && (INTVAL (inc_val) == size && offset == 0))
7111 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
7113 else if (HAVE_POST_DECREMENT
7114 && (INTVAL (inc_val) == -size && offset == 0))
7115 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
7117 else if (HAVE_PRE_INCREMENT
7118 && (INTVAL (inc_val) == size && offset == size))
7119 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
7121 else if (HAVE_PRE_DECREMENT
7122 && (INTVAL (inc_val) == -size && offset == -size))
7123 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
7125 else if (HAVE_POST_MODIFY_DISP && offset == 0)
7126 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
7127 gen_rtx_PLUS (Pmode,
7130 insn, x, incr, addr);
7132 else if (GET_CODE (inc_val) == REG
7133 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
7137 if (HAVE_POST_MODIFY_REG && offset == 0)
7138 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
7139 gen_rtx_PLUS (Pmode,
7142 insn, x, incr, addr);
7146 #endif /* AUTO_INC_DEC */
7149 mark_used_reg (pbi, reg, cond, insn)
7150 struct propagate_block_info *pbi;
7152 rtx cond ATTRIBUTE_UNUSED;
7155 unsigned int regno_first, regno_last, i;
7156 int some_was_live, some_was_dead, some_not_set;
7158 regno_last = regno_first = REGNO (reg);
7159 if (regno_first < FIRST_PSEUDO_REGISTER)
7160 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
7162 /* Find out if any of this register is live after this instruction. */
7163 some_was_live = some_was_dead = 0;
7164 for (i = regno_first; i <= regno_last; ++i)
7166 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
7167 some_was_live |= needed_regno;
7168 some_was_dead |= ! needed_regno;
7171 /* Find out if any of the register was set this insn. */
7173 for (i = regno_first; i <= regno_last; ++i)
7174 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
7176 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
7178 /* Record where each reg is used, so when the reg is set we know
7179 the next insn that uses it. */
7180 pbi->reg_next_use[regno_first] = insn;
7183 if (pbi->flags & PROP_REG_INFO)
7185 if (regno_first < FIRST_PSEUDO_REGISTER)
7187 /* If this is a register we are going to try to eliminate,
7188 don't mark it live here. If we are successful in
7189 eliminating it, it need not be live unless it is used for
7190 pseudos, in which case it will have been set live when it
7191 was allocated to the pseudos. If the register will not
7192 be eliminated, reload will set it live at that point.
7194 Otherwise, record that this function uses this register. */
7195 /* ??? The PPC backend tries to "eliminate" on the pic
7196 register to itself. This should be fixed. In the mean
7197 time, hack around it. */
7199 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
7200 && (regno_first == FRAME_POINTER_REGNUM
7201 || regno_first == ARG_POINTER_REGNUM)))
7202 for (i = regno_first; i <= regno_last; ++i)
7203 regs_ever_live[i] = 1;
7207 /* Keep track of which basic block each reg appears in. */
7209 register int blocknum = pbi->bb->index;
7210 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
7211 REG_BASIC_BLOCK (regno_first) = blocknum;
7212 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
7213 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
7215 /* Count (weighted) number of uses of each reg. */
7216 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
7217 REG_N_REFS (regno_first)++;
7221 /* Record and count the insns in which a reg dies. If it is used in
7222 this insn and was dead below the insn then it dies in this insn.
7223 If it was set in this insn, we do not make a REG_DEAD note;
7224 likewise if we already made such a note. */
7225 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
7229 /* Check for the case where the register dying partially
7230 overlaps the register set by this insn. */
7231 if (regno_first != regno_last)
7232 for (i = regno_first; i <= regno_last; ++i)
7233 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
7235 /* If none of the words in X is needed, make a REG_DEAD note.
7236 Otherwise, we must make partial REG_DEAD notes. */
7237 if (! some_was_live)
7239 if ((pbi->flags & PROP_DEATH_NOTES)
7240 && ! find_regno_note (insn, REG_DEAD, regno_first))
7242 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
7244 if (pbi->flags & PROP_REG_INFO)
7245 REG_N_DEATHS (regno_first)++;
7249 /* Don't make a REG_DEAD note for a part of a register
7250 that is set in the insn. */
7251 for (i = regno_first; i <= regno_last; ++i)
7252 if (! REGNO_REG_SET_P (pbi->reg_live, i)
7253 && ! dead_or_set_regno_p (insn, i))
7255 = alloc_EXPR_LIST (REG_DEAD,
7256 gen_rtx_REG (reg_raw_mode[i], i),
7261 /* Mark the register as being live. */
7262 for (i = regno_first; i <= regno_last; ++i)
7264 SET_REGNO_REG_SET (pbi->reg_live, i);
7266 #ifdef HAVE_conditional_execution
7267 /* If this is a conditional use, record that fact. If it is later
7268 conditionally set, we'll know to kill the register. */
7269 if (cond != NULL_RTX)
7271 splay_tree_node node;
7272 struct reg_cond_life_info *rcli;
7277 node = splay_tree_lookup (pbi->reg_cond_dead, i);
7280 /* The register was unconditionally live previously.
7281 No need to do anything. */
7285 /* The register was conditionally live previously.
7286 Subtract the new life cond from the old death cond. */
7287 rcli = (struct reg_cond_life_info *) node->value;
7288 ncond = rcli->condition;
7289 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
7291 /* If the register is now unconditionally live,
7292 remove the entry in the splay_tree. */
7293 if (ncond == const0_rtx)
7294 splay_tree_remove (pbi->reg_cond_dead, i);
7297 rcli->condition = ncond;
7298 SET_REGNO_REG_SET (pbi->reg_cond_reg,
7299 REGNO (XEXP (cond, 0)));
7305 /* The register was not previously live at all. Record
7306 the condition under which it is still dead. */
7307 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
7308 rcli->condition = not_reg_cond (cond);
7309 rcli->stores = const0_rtx;
7310 rcli->orig_condition = const0_rtx;
7311 splay_tree_insert (pbi->reg_cond_dead, i,
7312 (splay_tree_value) rcli);
7314 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
7317 else if (some_was_live)
7319 /* The register may have been conditionally live previously, but
7320 is now unconditionally live. Remove it from the conditionally
7321 dead list, so that a conditional set won't cause us to think
7323 splay_tree_remove (pbi->reg_cond_dead, i);
7329 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
7330 This is done assuming the registers needed from X are those that
7331 have 1-bits in PBI->REG_LIVE.
7333 INSN is the containing instruction. If INSN is dead, this function
7337 mark_used_regs (pbi, x, cond, insn)
7338 struct propagate_block_info *pbi;
7341 register RTX_CODE code;
7343 int flags = pbi->flags;
7346 code = GET_CODE (x);
7366 /* If we are clobbering a MEM, mark any registers inside the address
7368 if (GET_CODE (XEXP (x, 0)) == MEM)
7369 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
7373 /* Don't bother watching stores to mems if this is not the
7374 final pass. We'll not be deleting dead stores this round. */
7375 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
7377 /* Invalidate the data for the last MEM stored, but only if MEM is
7378 something that can be stored into. */
7379 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
7380 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
7381 /* Needn't clear the memory set list. */
7385 rtx temp = pbi->mem_set_list;
7386 rtx prev = NULL_RTX;
7391 next = XEXP (temp, 1);
7392 if (anti_dependence (XEXP (temp, 0), x))
7394 /* Splice temp out of the list. */
7396 XEXP (prev, 1) = next;
7398 pbi->mem_set_list = next;
7399 free_EXPR_LIST_node (temp);
7400 pbi->mem_set_list_len--;
7408 /* If the memory reference had embedded side effects (autoincrement
7409 address modes. Then we may need to kill some entries on the
7412 invalidate_mems_from_autoinc (pbi, insn);
7416 if (flags & PROP_AUTOINC)
7417 find_auto_inc (pbi, x, insn);
7422 #ifdef CLASS_CANNOT_CHANGE_MODE
7423 if (GET_CODE (SUBREG_REG (x)) == REG
7424 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
7425 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
7426 GET_MODE (SUBREG_REG (x))))
7427 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
7430 /* While we're here, optimize this case. */
7432 if (GET_CODE (x) != REG)
7437 /* See a register other than being set => mark it as needed. */
7438 mark_used_reg (pbi, x, cond, insn);
7443 register rtx testreg = SET_DEST (x);
7446 /* If storing into MEM, don't show it as being used. But do
7447 show the address as being used. */
7448 if (GET_CODE (testreg) == MEM)
7451 if (flags & PROP_AUTOINC)
7452 find_auto_inc (pbi, testreg, insn);
7454 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
7455 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7459 /* Storing in STRICT_LOW_PART is like storing in a reg
7460 in that this SET might be dead, so ignore it in TESTREG.
7461 but in some other ways it is like using the reg.
7463 Storing in a SUBREG or a bit field is like storing the entire
7464 register in that if the register's value is not used
7465 then this SET is not needed. */
7466 while (GET_CODE (testreg) == STRICT_LOW_PART
7467 || GET_CODE (testreg) == ZERO_EXTRACT
7468 || GET_CODE (testreg) == SIGN_EXTRACT
7469 || GET_CODE (testreg) == SUBREG)
7471 #ifdef CLASS_CANNOT_CHANGE_MODE
7472 if (GET_CODE (testreg) == SUBREG
7473 && GET_CODE (SUBREG_REG (testreg)) == REG
7474 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
7475 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
7476 GET_MODE (testreg)))
7477 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
7480 /* Modifying a single register in an alternate mode
7481 does not use any of the old value. But these other
7482 ways of storing in a register do use the old value. */
7483 if (GET_CODE (testreg) == SUBREG
7484 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
7489 testreg = XEXP (testreg, 0);
7492 /* If this is a store into a register or group of registers,
7493 recursively scan the value being stored. */
7495 if ((GET_CODE (testreg) == PARALLEL
7496 && GET_MODE (testreg) == BLKmode)
7497 || (GET_CODE (testreg) == REG
7498 && (regno = REGNO (testreg),
7499 ! (regno == FRAME_POINTER_REGNUM
7500 && (! reload_completed || frame_pointer_needed)))
7501 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
7502 && ! (regno == HARD_FRAME_POINTER_REGNUM
7503 && (! reload_completed || frame_pointer_needed))
7505 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
7506 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
7511 mark_used_regs (pbi, SET_DEST (x), cond, insn);
7512 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7519 case UNSPEC_VOLATILE:
7523 /* Traditional and volatile asm instructions must be considered to use
7524 and clobber all hard registers, all pseudo-registers and all of
7525 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
7527 Consider for instance a volatile asm that changes the fpu rounding
7528 mode. An insn should not be moved across this even if it only uses
7529 pseudo-regs because it might give an incorrectly rounded result.
7531 ?!? Unfortunately, marking all hard registers as live causes massive
7532 problems for the register allocator and marking all pseudos as live
7533 creates mountains of uninitialized variable warnings.
7535 So for now, just clear the memory set list and mark any regs
7536 we can find in ASM_OPERANDS as used. */
7537 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
7539 free_EXPR_LIST_list (&pbi->mem_set_list);
7540 pbi->mem_set_list_len = 0;
7543 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
7544 We can not just fall through here since then we would be confused
7545 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
7546 traditional asms unlike their normal usage. */
7547 if (code == ASM_OPERANDS)
7551 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
7552 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
7558 if (cond != NULL_RTX)
7561 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
7563 cond = COND_EXEC_TEST (x);
7564 x = COND_EXEC_CODE (x);
7568 /* We _do_not_ want to scan operands of phi nodes. Operands of
7569 a phi function are evaluated only when control reaches this
7570 block along a particular edge. Therefore, regs that appear
7571 as arguments to phi should not be added to the global live at
7579 /* Recursively scan the operands of this expression. */
7582 register const char *fmt = GET_RTX_FORMAT (code);
7585 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7589 /* Tail recursive case: save a function call level. */
7595 mark_used_regs (pbi, XEXP (x, i), cond, insn);
7597 else if (fmt[i] == 'E')
7600 for (j = 0; j < XVECLEN (x, i); j++)
7601 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
7610 try_pre_increment_1 (pbi, insn)
7611 struct propagate_block_info *pbi;
7614 /* Find the next use of this reg. If in same basic block,
7615 make it do pre-increment or pre-decrement if appropriate. */
7616 rtx x = single_set (insn);
7617 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
7618 * INTVAL (XEXP (SET_SRC (x), 1)));
7619 int regno = REGNO (SET_DEST (x));
7620 rtx y = pbi->reg_next_use[regno];
7622 && SET_DEST (x) != stack_pointer_rtx
7623 && BLOCK_NUM (y) == BLOCK_NUM (insn)
7624 /* Don't do this if the reg dies, or gets set in y; a standard addressing
7625 mode would be better. */
7626 && ! dead_or_set_p (y, SET_DEST (x))
7627 && try_pre_increment (y, SET_DEST (x), amount))
7629 /* We have found a suitable auto-increment and already changed
7630 insn Y to do it. So flush this increment instruction. */
7631 propagate_block_delete_insn (pbi->bb, insn);
7633 /* Count a reference to this reg for the increment insn we are
7634 deleting. When a reg is incremented, spilling it is worse,
7635 so we want to make that less likely. */
7636 if (regno >= FIRST_PSEUDO_REGISTER)
7638 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
7639 REG_N_SETS (regno)++;
7642 /* Flush any remembered memories depending on the value of
7643 the incremented register. */
7644 invalidate_mems_from_set (pbi, SET_DEST (x));
7651 /* Try to change INSN so that it does pre-increment or pre-decrement
7652 addressing on register REG in order to add AMOUNT to REG.
7653 AMOUNT is negative for pre-decrement.
7654 Returns 1 if the change could be made.
7655 This checks all about the validity of the result of modifying INSN. */
7658 try_pre_increment (insn, reg, amount)
7660 HOST_WIDE_INT amount;
7664 /* Nonzero if we can try to make a pre-increment or pre-decrement.
7665 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
7667 /* Nonzero if we can try to make a post-increment or post-decrement.
7668 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
7669 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
7670 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
7673 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
7676 /* From the sign of increment, see which possibilities are conceivable
7677 on this target machine. */
7678 if (HAVE_PRE_INCREMENT && amount > 0)
7680 if (HAVE_POST_INCREMENT && amount > 0)
7683 if (HAVE_PRE_DECREMENT && amount < 0)
7685 if (HAVE_POST_DECREMENT && amount < 0)
7688 if (! (pre_ok || post_ok))
7691 /* It is not safe to add a side effect to a jump insn
7692 because if the incremented register is spilled and must be reloaded
7693 there would be no way to store the incremented value back in memory. */
7695 if (GET_CODE (insn) == JUMP_INSN)
7700 use = find_use_as_address (PATTERN (insn), reg, 0);
7701 if (post_ok && (use == 0 || use == (rtx) 1))
7703 use = find_use_as_address (PATTERN (insn), reg, -amount);
7707 if (use == 0 || use == (rtx) 1)
7710 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
7713 /* See if this combination of instruction and addressing mode exists. */
7714 if (! validate_change (insn, &XEXP (use, 0),
7715 gen_rtx_fmt_e (amount > 0
7716 ? (do_post ? POST_INC : PRE_INC)
7717 : (do_post ? POST_DEC : PRE_DEC),
7721 /* Record that this insn now has an implicit side effect on X. */
7722 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
7726 #endif /* AUTO_INC_DEC */
7728 /* Find the place in the rtx X where REG is used as a memory address.
7729 Return the MEM rtx that so uses it.
7730 If PLUSCONST is nonzero, search instead for a memory address equivalent to
7731 (plus REG (const_int PLUSCONST)).
7733 If such an address does not appear, return 0.
7734 If REG appears more than once, or is used other than in such an address,
7738 find_use_as_address (x, reg, plusconst)
7741 HOST_WIDE_INT plusconst;
7743 enum rtx_code code = GET_CODE (x);
7744 const char *fmt = GET_RTX_FORMAT (code);
7746 register rtx value = 0;
7749 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
7752 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
7753 && XEXP (XEXP (x, 0), 0) == reg
7754 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
7755 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
7758 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
7760 /* If REG occurs inside a MEM used in a bit-field reference,
7761 that is unacceptable. */
7762 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
7763 return (rtx) (HOST_WIDE_INT) 1;
7767 return (rtx) (HOST_WIDE_INT) 1;
7769 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7773 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
7777 return (rtx) (HOST_WIDE_INT) 1;
7779 else if (fmt[i] == 'E')
7782 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7784 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
7788 return (rtx) (HOST_WIDE_INT) 1;
7796 /* Write information about registers and basic blocks into FILE.
7797 This is part of making a debugging dump. */
7800 dump_regset (r, outf)
7807 fputs (" (nil)", outf);
7811 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
7813 fprintf (outf, " %d", i);
7814 if (i < FIRST_PSEUDO_REGISTER)
7815 fprintf (outf, " [%s]",
7820 /* Print a human-reaable representation of R on the standard error
7821 stream. This function is designed to be used from within the
7828 dump_regset (r, stderr);
7829 putc ('\n', stderr);
7833 dump_flow_info (file)
7837 static const char * const reg_class_names[] = REG_CLASS_NAMES;
7839 fprintf (file, "%d registers.\n", max_regno);
7840 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
7843 enum reg_class class, altclass;
7844 fprintf (file, "\nRegister %d used %d times across %d insns",
7845 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
7846 if (REG_BASIC_BLOCK (i) >= 0)
7847 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
7849 fprintf (file, "; set %d time%s", REG_N_SETS (i),
7850 (REG_N_SETS (i) == 1) ? "" : "s");
7851 if (REG_USERVAR_P (regno_reg_rtx[i]))
7852 fprintf (file, "; user var");
7853 if (REG_N_DEATHS (i) != 1)
7854 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
7855 if (REG_N_CALLS_CROSSED (i) == 1)
7856 fprintf (file, "; crosses 1 call");
7857 else if (REG_N_CALLS_CROSSED (i))
7858 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
7859 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
7860 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
7861 class = reg_preferred_class (i);
7862 altclass = reg_alternate_class (i);
7863 if (class != GENERAL_REGS || altclass != ALL_REGS)
7865 if (altclass == ALL_REGS || class == ALL_REGS)
7866 fprintf (file, "; pref %s", reg_class_names[(int) class]);
7867 else if (altclass == NO_REGS)
7868 fprintf (file, "; %s or none", reg_class_names[(int) class]);
7870 fprintf (file, "; pref %s, else %s",
7871 reg_class_names[(int) class],
7872 reg_class_names[(int) altclass]);
7874 if (REG_POINTER (regno_reg_rtx[i]))
7875 fprintf (file, "; pointer");
7876 fprintf (file, ".\n");
7879 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
7880 for (i = 0; i < n_basic_blocks; i++)
7882 register basic_block bb = BASIC_BLOCK (i);
7885 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count ",
7886 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth);
7887 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7888 fprintf (file, ", freq %i.\n", bb->frequency);
7890 fprintf (file, "Predecessors: ");
7891 for (e = bb->pred; e; e = e->pred_next)
7892 dump_edge_info (file, e, 0);
7894 fprintf (file, "\nSuccessors: ");
7895 for (e = bb->succ; e; e = e->succ_next)
7896 dump_edge_info (file, e, 1);
7898 fprintf (file, "\nRegisters live at start:");
7899 dump_regset (bb->global_live_at_start, file);
7901 fprintf (file, "\nRegisters live at end:");
7902 dump_regset (bb->global_live_at_end, file);
7913 dump_flow_info (stderr);
7917 dump_edge_info (file, e, do_succ)
7922 basic_block side = (do_succ ? e->dest : e->src);
7924 if (side == ENTRY_BLOCK_PTR)
7925 fputs (" ENTRY", file);
7926 else if (side == EXIT_BLOCK_PTR)
7927 fputs (" EXIT", file);
7929 fprintf (file, " %d", side->index);
7932 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
7936 fprintf (file, " count:");
7937 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) e->count);
7942 static const char * const bitnames[] = {
7943 "fallthru", "crit", "ab", "abcall", "eh", "fake", "dfs_back"
7946 int i, flags = e->flags;
7950 for (i = 0; flags; i++)
7951 if (flags & (1 << i))
7957 if (i < (int) ARRAY_SIZE (bitnames))
7958 fputs (bitnames[i], file);
7960 fprintf (file, "%d", i);
7967 /* Print out one basic block with live information at start and end. */
7978 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
7979 bb->index, bb->loop_depth);
7980 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7983 fputs (";; Predecessors: ", outf);
7984 for (e = bb->pred; e; e = e->pred_next)
7985 dump_edge_info (outf, e, 0);
7988 fputs (";; Registers live at start:", outf);
7989 dump_regset (bb->global_live_at_start, outf);
7992 for (insn = bb->head, last = NEXT_INSN (bb->end);
7994 insn = NEXT_INSN (insn))
7995 print_rtl_single (outf, insn);
7997 fputs (";; Registers live at end:", outf);
7998 dump_regset (bb->global_live_at_end, outf);
8001 fputs (";; Successors: ", outf);
8002 for (e = bb->succ; e; e = e->succ_next)
8003 dump_edge_info (outf, e, 1);
8011 dump_bb (bb, stderr);
8018 dump_bb (BASIC_BLOCK (n), stderr);
8021 /* Like print_rtl, but also print out live information for the start of each
8025 print_rtl_with_bb (outf, rtx_first)
8029 register rtx tmp_rtx;
8032 fprintf (outf, "(nil)\n");
8036 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
8037 int max_uid = get_max_uid ();
8038 basic_block *start = (basic_block *)
8039 xcalloc (max_uid, sizeof (basic_block));
8040 basic_block *end = (basic_block *)
8041 xcalloc (max_uid, sizeof (basic_block));
8042 enum bb_state *in_bb_p = (enum bb_state *)
8043 xcalloc (max_uid, sizeof (enum bb_state));
8045 for (i = n_basic_blocks - 1; i >= 0; i--)
8047 basic_block bb = BASIC_BLOCK (i);
8050 start[INSN_UID (bb->head)] = bb;
8051 end[INSN_UID (bb->end)] = bb;
8052 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
8054 enum bb_state state = IN_MULTIPLE_BB;
8055 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
8057 in_bb_p[INSN_UID (x)] = state;
8064 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
8069 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
8071 fprintf (outf, ";; Start of basic block %d, registers live:",
8073 dump_regset (bb->global_live_at_start, outf);
8077 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
8078 && GET_CODE (tmp_rtx) != NOTE
8079 && GET_CODE (tmp_rtx) != BARRIER)
8080 fprintf (outf, ";; Insn is not within a basic block\n");
8081 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
8082 fprintf (outf, ";; Insn is in multiple basic blocks\n");
8084 did_output = print_rtl_single (outf, tmp_rtx);
8086 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
8088 fprintf (outf, ";; End of basic block %d, registers live:\n",
8090 dump_regset (bb->global_live_at_end, outf);
8103 if (current_function_epilogue_delay_list != 0)
8105 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
8106 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
8107 tmp_rtx = XEXP (tmp_rtx, 1))
8108 print_rtl_single (outf, XEXP (tmp_rtx, 0));
8112 /* Dump the rtl into the current debugging dump file, then abort. */
8115 print_rtl_and_abort_fcn (file, line, function)
8118 const char *function;
8122 print_rtl_with_bb (rtl_dump_file, get_insns ());
8123 fclose (rtl_dump_file);
8126 fancy_abort (file, line, function);
8129 /* Recompute register set/reference counts immediately prior to register
8132 This avoids problems with set/reference counts changing to/from values
8133 which have special meanings to the register allocators.
8135 Additionally, the reference counts are the primary component used by the
8136 register allocators to prioritize pseudos for allocation to hard regs.
8137 More accurate reference counts generally lead to better register allocation.
8139 F is the first insn to be scanned.
8141 LOOP_STEP denotes how much loop_depth should be incremented per
8142 loop nesting level in order to increase the ref count more for
8143 references in a loop.
8145 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
8146 possibly other information which is used by the register allocators. */
8149 recompute_reg_usage (f, loop_step)
8150 rtx f ATTRIBUTE_UNUSED;
8151 int loop_step ATTRIBUTE_UNUSED;
8153 allocate_reg_life_data ();
8154 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
8157 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
8158 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
8159 of the number of registers that died. */
8162 count_or_remove_death_notes (blocks, kill)
8168 for (i = n_basic_blocks - 1; i >= 0; --i)
8173 if (blocks && ! TEST_BIT (blocks, i))
8176 bb = BASIC_BLOCK (i);
8178 for (insn = bb->head;; insn = NEXT_INSN (insn))
8182 rtx *pprev = ®_NOTES (insn);
8187 switch (REG_NOTE_KIND (link))
8190 if (GET_CODE (XEXP (link, 0)) == REG)
8192 rtx reg = XEXP (link, 0);
8195 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
8198 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
8206 rtx next = XEXP (link, 1);
8207 free_EXPR_LIST_node (link);
8208 *pprev = link = next;
8214 pprev = &XEXP (link, 1);
8221 if (insn == bb->end)
8230 /* Update insns block within BB. */
8233 update_bb_for_insn (bb)
8238 if (! basic_block_for_insn)
8241 for (insn = bb->head; ; insn = NEXT_INSN (insn))
8243 set_block_for_insn (insn, bb);
8245 if (insn == bb->end)
8251 /* Record INSN's block as BB. */
8254 set_block_for_insn (insn, bb)
8258 size_t uid = INSN_UID (insn);
8259 if (uid >= basic_block_for_insn->num_elements)
8263 /* Add one-eighth the size so we don't keep calling xrealloc. */
8264 new_size = uid + (uid + 7) / 8;
8266 VARRAY_GROW (basic_block_for_insn, new_size);
8268 VARRAY_BB (basic_block_for_insn, uid) = bb;
8271 /* When a new insn has been inserted into an existing block, it will
8272 sometimes emit more than a single insn. This routine will set the
8273 block number for the specified insn, and look backwards in the insn
8274 chain to see if there are any other uninitialized insns immediately
8275 previous to this one, and set the block number for them too. */
8278 set_block_for_new_insns (insn, bb)
8282 set_block_for_insn (insn, bb);
8284 /* Scan the previous instructions setting the block number until we find
8285 an instruction that has the block number set, or we find a note
8287 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
8289 if (GET_CODE (insn) == NOTE)
8291 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
8292 || BLOCK_FOR_INSN (insn) == 0)
8293 set_block_for_insn (insn, bb);
8299 /* Verify the CFG consistency. This function check some CFG invariants and
8300 aborts when something is wrong. Hope that this function will help to
8301 convert many optimization passes to preserve CFG consistent.
8303 Currently it does following checks:
8305 - test head/end pointers
8306 - overlapping of basic blocks
8307 - edge list correctness
8308 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
8309 - tails of basic blocks (ensure that boundary is necesary)
8310 - scans body of the basic block for JUMP_INSN, CODE_LABEL
8311 and NOTE_INSN_BASIC_BLOCK
8312 - check that all insns are in the basic blocks
8313 (except the switch handling code, barriers and notes)
8314 - check that all returns are followed by barriers
8316 In future it can be extended check a lot of other stuff as well
8317 (reachability of basic blocks, life information, etc. etc.). */
8322 const int max_uid = get_max_uid ();
8323 const rtx rtx_first = get_insns ();
8324 rtx last_head = get_last_insn ();
8325 basic_block *bb_info, *last_visited;
8327 int i, last_bb_num_seen, num_bb_notes, err = 0;
8329 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
8330 last_visited = (basic_block *) xcalloc (n_basic_blocks + 2,
8331 sizeof (basic_block));
8333 for (i = n_basic_blocks - 1; i >= 0; i--)
8335 basic_block bb = BASIC_BLOCK (i);
8336 rtx head = bb->head;
8339 /* Verify the end of the basic block is in the INSN chain. */
8340 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
8345 error ("End insn %d for block %d not found in the insn stream.",
8346 INSN_UID (end), bb->index);
8350 /* Work backwards from the end to the head of the basic block
8351 to verify the head is in the RTL chain. */
8352 for (; x != NULL_RTX; x = PREV_INSN (x))
8354 /* While walking over the insn chain, verify insns appear
8355 in only one basic block and initialize the BB_INFO array
8356 used by other passes. */
8357 if (bb_info[INSN_UID (x)] != NULL)
8359 error ("Insn %d is in multiple basic blocks (%d and %d)",
8360 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
8363 bb_info[INSN_UID (x)] = bb;
8370 error ("Head insn %d for block %d not found in the insn stream.",
8371 INSN_UID (head), bb->index);
8378 /* Now check the basic blocks (boundaries etc.) */
8379 for (i = n_basic_blocks - 1; i >= 0; i--)
8381 basic_block bb = BASIC_BLOCK (i);
8382 /* Check correctness of edge lists. */
8384 int has_fallthru = 0;
8389 if (last_visited [e->dest->index + 2] == bb)
8391 error ("verify_flow_info: Duplicate edge %i->%i",
8392 e->src->index, e->dest->index);
8395 last_visited [e->dest->index + 2] = bb;
8397 if (e->flags & EDGE_FALLTHRU)
8400 if ((e->flags & EDGE_FALLTHRU)
8401 && e->src != ENTRY_BLOCK_PTR
8402 && e->dest != EXIT_BLOCK_PTR)
8405 if (e->src->index + 1 != e->dest->index)
8407 error ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
8408 e->src->index, e->dest->index);
8412 for (insn = NEXT_INSN (e->src->end); insn != e->dest->head;
8413 insn = NEXT_INSN (insn))
8414 if (GET_CODE (insn) == BARRIER || INSN_P (insn))
8416 error ("verify_flow_info: Incorrect fallthru %i->%i",
8417 e->src->index, e->dest->index);
8418 fatal_insn ("Wrong insn in the fallthru edge", insn);
8424 error ("verify_flow_info: Basic block %d succ edge is corrupted",
8426 fprintf (stderr, "Predecessor: ");
8427 dump_edge_info (stderr, e, 0);
8428 fprintf (stderr, "\nSuccessor: ");
8429 dump_edge_info (stderr, e, 1);
8430 fprintf (stderr, "\n");
8433 if (e->dest != EXIT_BLOCK_PTR)
8435 edge e2 = e->dest->pred;
8436 while (e2 && e2 != e)
8440 error ("Basic block %i edge lists are corrupted", bb->index);
8450 /* Ensure existence of barrier in BB with no fallthru edges. */
8451 for (insn = bb->end; GET_CODE (insn) != BARRIER;
8452 insn = NEXT_INSN (insn))
8454 || (GET_CODE (insn) == NOTE
8455 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
8457 error ("Missing barrier after block %i", bb->index);
8467 error ("Basic block %d pred edge is corrupted", bb->index);
8468 fputs ("Predecessor: ", stderr);
8469 dump_edge_info (stderr, e, 0);
8470 fputs ("\nSuccessor: ", stderr);
8471 dump_edge_info (stderr, e, 1);
8472 fputc ('\n', stderr);
8475 if (e->src != ENTRY_BLOCK_PTR)
8477 edge e2 = e->src->succ;
8478 while (e2 && e2 != e)
8482 error ("Basic block %i edge lists are corrupted", bb->index);
8489 /* OK pointers are correct. Now check the header of basic
8490 block. It ought to contain optional CODE_LABEL followed
8491 by NOTE_BASIC_BLOCK. */
8493 if (GET_CODE (x) == CODE_LABEL)
8497 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
8503 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
8505 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
8512 /* Do checks for empty blocks here */
8519 if (NOTE_INSN_BASIC_BLOCK_P (x))
8521 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
8522 INSN_UID (x), bb->index);
8529 if (GET_CODE (x) == JUMP_INSN
8530 || GET_CODE (x) == CODE_LABEL
8531 || GET_CODE (x) == BARRIER)
8533 error ("In basic block %d:", bb->index);
8534 fatal_insn ("Flow control insn inside a basic block", x);
8542 last_bb_num_seen = -1;
8547 if (NOTE_INSN_BASIC_BLOCK_P (x))
8549 basic_block bb = NOTE_BASIC_BLOCK (x);
8551 if (bb->index != last_bb_num_seen + 1)
8552 internal_error ("Basic blocks not numbered consecutively.");
8554 last_bb_num_seen = bb->index;
8557 if (!bb_info[INSN_UID (x)])
8559 switch (GET_CODE (x))
8566 /* An addr_vec is placed outside any block block. */
8568 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
8569 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
8570 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
8575 /* But in any case, non-deletable labels can appear anywhere. */
8579 fatal_insn ("Insn outside basic block", x);
8584 && GET_CODE (x) == JUMP_INSN
8585 && returnjump_p (x) && ! condjump_p (x)
8586 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
8587 fatal_insn ("Return not followed by barrier", x);
8592 if (num_bb_notes != n_basic_blocks)
8594 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
8595 num_bb_notes, n_basic_blocks);
8598 internal_error ("verify_flow_info failed.");
8602 free (last_visited);
8605 /* Functions to access an edge list with a vector representation.
8606 Enough data is kept such that given an index number, the
8607 pred and succ that edge represents can be determined, or
8608 given a pred and a succ, its index number can be returned.
8609 This allows algorithms which consume a lot of memory to
8610 represent the normally full matrix of edge (pred,succ) with a
8611 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
8612 wasted space in the client code due to sparse flow graphs. */
8614 /* This functions initializes the edge list. Basically the entire
8615 flowgraph is processed, and all edges are assigned a number,
8616 and the data structure is filled in. */
8621 struct edge_list *elist;
8627 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
8631 /* Determine the number of edges in the flow graph by counting successor
8632 edges on each basic block. */
8633 for (x = 0; x < n_basic_blocks; x++)
8635 basic_block bb = BASIC_BLOCK (x);
8637 for (e = bb->succ; e; e = e->succ_next)
8640 /* Don't forget successors of the entry block. */
8641 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8644 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
8645 elist->num_blocks = block_count;
8646 elist->num_edges = num_edges;
8647 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
8651 /* Follow successors of the entry block, and register these edges. */
8652 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8654 elist->index_to_edge[num_edges] = e;
8658 for (x = 0; x < n_basic_blocks; x++)
8660 basic_block bb = BASIC_BLOCK (x);
8662 /* Follow all successors of blocks, and register these edges. */
8663 for (e = bb->succ; e; e = e->succ_next)
8665 elist->index_to_edge[num_edges] = e;
8672 /* This function free's memory associated with an edge list. */
8675 free_edge_list (elist)
8676 struct edge_list *elist;
8680 free (elist->index_to_edge);
8685 /* This function provides debug output showing an edge list. */
8688 print_edge_list (f, elist)
8690 struct edge_list *elist;
8693 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
8694 elist->num_blocks - 2, elist->num_edges);
8696 for (x = 0; x < elist->num_edges; x++)
8698 fprintf (f, " %-4d - edge(", x);
8699 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
8700 fprintf (f, "entry,");
8702 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
8704 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
8705 fprintf (f, "exit)\n");
8707 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
8711 /* This function provides an internal consistency check of an edge list,
8712 verifying that all edges are present, and that there are no
8716 verify_edge_list (f, elist)
8718 struct edge_list *elist;
8720 int x, pred, succ, index;
8723 for (x = 0; x < n_basic_blocks; x++)
8725 basic_block bb = BASIC_BLOCK (x);
8727 for (e = bb->succ; e; e = e->succ_next)
8729 pred = e->src->index;
8730 succ = e->dest->index;
8731 index = EDGE_INDEX (elist, e->src, e->dest);
8732 if (index == EDGE_INDEX_NO_EDGE)
8734 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8737 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8738 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8739 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8740 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8741 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8742 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8745 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8747 pred = e->src->index;
8748 succ = e->dest->index;
8749 index = EDGE_INDEX (elist, e->src, e->dest);
8750 if (index == EDGE_INDEX_NO_EDGE)
8752 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8755 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8756 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8757 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8758 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8759 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8760 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8762 /* We've verified that all the edges are in the list, no lets make sure
8763 there are no spurious edges in the list. */
8765 for (pred = 0; pred < n_basic_blocks; pred++)
8766 for (succ = 0; succ < n_basic_blocks; succ++)
8768 basic_block p = BASIC_BLOCK (pred);
8769 basic_block s = BASIC_BLOCK (succ);
8773 for (e = p->succ; e; e = e->succ_next)
8779 for (e = s->pred; e; e = e->pred_next)
8785 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8786 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8787 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
8789 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8790 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8791 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
8792 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8793 BASIC_BLOCK (succ)));
8795 for (succ = 0; succ < n_basic_blocks; succ++)
8797 basic_block p = ENTRY_BLOCK_PTR;
8798 basic_block s = BASIC_BLOCK (succ);
8802 for (e = p->succ; e; e = e->succ_next)
8808 for (e = s->pred; e; e = e->pred_next)
8814 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8815 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8816 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
8818 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8819 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8820 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
8821 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
8822 BASIC_BLOCK (succ)));
8824 for (pred = 0; pred < n_basic_blocks; pred++)
8826 basic_block p = BASIC_BLOCK (pred);
8827 basic_block s = EXIT_BLOCK_PTR;
8831 for (e = p->succ; e; e = e->succ_next)
8837 for (e = s->pred; e; e = e->pred_next)
8843 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8844 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8845 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
8847 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8848 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8849 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
8850 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8855 /* This routine will determine what, if any, edge there is between
8856 a specified predecessor and successor. */
8859 find_edge_index (edge_list, pred, succ)
8860 struct edge_list *edge_list;
8861 basic_block pred, succ;
8864 for (x = 0; x < NUM_EDGES (edge_list); x++)
8866 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
8867 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
8870 return (EDGE_INDEX_NO_EDGE);
8873 /* This function will remove an edge from the flow graph. */
8879 edge last_pred = NULL;
8880 edge last_succ = NULL;
8882 basic_block src, dest;
8885 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
8891 last_succ->succ_next = e->succ_next;
8893 src->succ = e->succ_next;
8895 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
8901 last_pred->pred_next = e->pred_next;
8903 dest->pred = e->pred_next;
8909 /* This routine will remove any fake successor edges for a basic block.
8910 When the edge is removed, it is also removed from whatever predecessor
8914 remove_fake_successors (bb)
8918 for (e = bb->succ; e;)
8922 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
8927 /* This routine will remove all fake edges from the flow graph. If
8928 we remove all fake successors, it will automatically remove all
8929 fake predecessors. */
8932 remove_fake_edges ()
8936 for (x = 0; x < n_basic_blocks; x++)
8937 remove_fake_successors (BASIC_BLOCK (x));
8939 /* We've handled all successors except the entry block's. */
8940 remove_fake_successors (ENTRY_BLOCK_PTR);
8943 /* This function will add a fake edge between any block which has no
8944 successors, and the exit block. Some data flow equations require these
8948 add_noreturn_fake_exit_edges ()
8952 for (x = 0; x < n_basic_blocks; x++)
8953 if (BASIC_BLOCK (x)->succ == NULL)
8954 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
8957 /* This function adds a fake edge between any infinite loops to the
8958 exit block. Some optimizations require a path from each node to
8961 See also Morgan, Figure 3.10, pp. 82-83.
8963 The current implementation is ugly, not attempting to minimize the
8964 number of inserted fake edges. To reduce the number of fake edges
8965 to insert, add fake edges from _innermost_ loops containing only
8966 nodes not reachable from the exit block. */
8969 connect_infinite_loops_to_exit ()
8971 basic_block unvisited_block;
8973 /* Perform depth-first search in the reverse graph to find nodes
8974 reachable from the exit block. */
8975 struct depth_first_search_dsS dfs_ds;
8977 flow_dfs_compute_reverse_init (&dfs_ds);
8978 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
8980 /* Repeatedly add fake edges, updating the unreachable nodes. */
8983 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
8984 if (!unvisited_block)
8986 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
8987 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
8990 flow_dfs_compute_reverse_finish (&dfs_ds);
8995 /* Redirect an edge's successor from one block to another. */
8998 redirect_edge_succ (e, new_succ)
9000 basic_block new_succ;
9004 /* Disconnect the edge from the old successor block. */
9005 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
9007 *pe = (*pe)->pred_next;
9009 /* Reconnect the edge to the new successor block. */
9010 e->pred_next = new_succ->pred;
9015 /* Like previous but avoid possible dupplicate edge. */
9018 redirect_edge_succ_nodup (e, new_succ)
9020 basic_block new_succ;
9023 /* Check whether the edge is already present. */
9024 for (s = e->src->succ; s; s = s->succ_next)
9025 if (s->dest == new_succ && s != e)
9029 s->flags |= e->flags;
9030 s->probability += e->probability;
9031 s->count += e->count;
9035 redirect_edge_succ (e, new_succ);
9038 /* Redirect an edge's predecessor from one block to another. */
9041 redirect_edge_pred (e, new_pred)
9043 basic_block new_pred;
9047 /* Disconnect the edge from the old predecessor block. */
9048 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
9050 *pe = (*pe)->succ_next;
9052 /* Reconnect the edge to the new predecessor block. */
9053 e->succ_next = new_pred->succ;
9058 /* Dump the list of basic blocks in the bitmap NODES. */
9061 flow_nodes_print (str, nodes, file)
9063 const sbitmap nodes;
9071 fprintf (file, "%s { ", str);
9072 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
9073 fputs ("}\n", file);
9077 /* Dump the list of edges in the array EDGE_LIST. */
9080 flow_edge_list_print (str, edge_list, num_edges, file)
9082 const edge *edge_list;
9091 fprintf (file, "%s { ", str);
9092 for (i = 0; i < num_edges; i++)
9093 fprintf (file, "%d->%d ", edge_list[i]->src->index,
9094 edge_list[i]->dest->index);
9095 fputs ("}\n", file);
9099 /* Dump loop related CFG information. */
9102 flow_loops_cfg_dump (loops, file)
9103 const struct loops *loops;
9108 if (! loops->num || ! file || ! loops->cfg.dom)
9111 for (i = 0; i < n_basic_blocks; i++)
9115 fprintf (file, ";; %d succs { ", i);
9116 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
9117 fprintf (file, "%d ", succ->dest->index);
9118 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
9121 /* Dump the DFS node order. */
9122 if (loops->cfg.dfs_order)
9124 fputs (";; DFS order: ", file);
9125 for (i = 0; i < n_basic_blocks; i++)
9126 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
9129 /* Dump the reverse completion node order. */
9130 if (loops->cfg.rc_order)
9132 fputs (";; RC order: ", file);
9133 for (i = 0; i < n_basic_blocks; i++)
9134 fprintf (file, "%d ", loops->cfg.rc_order[i]);
9139 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
9142 flow_loop_nested_p (outer, loop)
9146 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
9150 /* Dump the loop information specified by LOOP to the stream FILE
9151 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
9153 flow_loop_dump (loop, file, loop_dump_aux, verbose)
9154 const struct loop *loop;
9156 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
9159 if (! loop || ! loop->header)
9162 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
9163 loop->num, INSN_UID (loop->first->head),
9164 INSN_UID (loop->last->end),
9165 loop->shared ? " shared" : "",
9166 loop->invalid ? " invalid" : "");
9167 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
9168 loop->header->index, loop->latch->index,
9169 loop->pre_header ? loop->pre_header->index : -1,
9170 loop->first->index, loop->last->index);
9171 fprintf (file, ";; depth %d, level %d, outer %ld\n",
9172 loop->depth, loop->level,
9173 (long) (loop->outer ? loop->outer->num : -1));
9175 if (loop->pre_header_edges)
9176 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
9177 loop->num_pre_header_edges, file);
9178 flow_edge_list_print (";; entry edges", loop->entry_edges,
9179 loop->num_entries, file);
9180 fprintf (file, ";; %d", loop->num_nodes);
9181 flow_nodes_print (" nodes", loop->nodes, file);
9182 flow_edge_list_print (";; exit edges", loop->exit_edges,
9183 loop->num_exits, file);
9184 if (loop->exits_doms)
9185 flow_nodes_print (";; exit doms", loop->exits_doms, file);
9187 loop_dump_aux (loop, file, verbose);
9191 /* Dump the loop information specified by LOOPS to the stream FILE,
9192 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
9194 flow_loops_dump (loops, file, loop_dump_aux, verbose)
9195 const struct loops *loops;
9197 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
9203 num_loops = loops->num;
9204 if (! num_loops || ! file)
9207 fprintf (file, ";; %d loops found, %d levels\n",
9208 num_loops, loops->levels);
9210 for (i = 0; i < num_loops; i++)
9212 struct loop *loop = &loops->array[i];
9214 flow_loop_dump (loop, file, loop_dump_aux, verbose);
9220 for (j = 0; j < i; j++)
9222 struct loop *oloop = &loops->array[j];
9224 if (loop->header == oloop->header)
9229 smaller = loop->num_nodes < oloop->num_nodes;
9231 /* If the union of LOOP and OLOOP is different than
9232 the larger of LOOP and OLOOP then LOOP and OLOOP
9233 must be disjoint. */
9234 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
9235 smaller ? oloop : loop);
9237 ";; loop header %d shared by loops %d, %d %s\n",
9238 loop->header->index, i, j,
9239 disjoint ? "disjoint" : "nested");
9246 flow_loops_cfg_dump (loops, file);
9250 /* Free all the memory allocated for LOOPS. */
9253 flow_loops_free (loops)
9254 struct loops *loops;
9263 /* Free the loop descriptors. */
9264 for (i = 0; i < loops->num; i++)
9266 struct loop *loop = &loops->array[i];
9268 if (loop->pre_header_edges)
9269 free (loop->pre_header_edges);
9271 sbitmap_free (loop->nodes);
9272 if (loop->entry_edges)
9273 free (loop->entry_edges);
9274 if (loop->exit_edges)
9275 free (loop->exit_edges);
9276 if (loop->exits_doms)
9277 sbitmap_free (loop->exits_doms);
9279 free (loops->array);
9280 loops->array = NULL;
9283 sbitmap_vector_free (loops->cfg.dom);
9284 if (loops->cfg.dfs_order)
9285 free (loops->cfg.dfs_order);
9287 if (loops->shared_headers)
9288 sbitmap_free (loops->shared_headers);
9293 /* Find the entry edges into the loop with header HEADER and nodes
9294 NODES and store in ENTRY_EDGES array. Return the number of entry
9295 edges from the loop. */
9298 flow_loop_entry_edges_find (header, nodes, entry_edges)
9300 const sbitmap nodes;
9306 *entry_edges = NULL;
9309 for (e = header->pred; e; e = e->pred_next)
9311 basic_block src = e->src;
9313 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
9320 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
9323 for (e = header->pred; e; e = e->pred_next)
9325 basic_block src = e->src;
9327 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
9328 (*entry_edges)[num_entries++] = e;
9335 /* Find the exit edges from the loop using the bitmap of loop nodes
9336 NODES and store in EXIT_EDGES array. Return the number of
9337 exit edges from the loop. */
9340 flow_loop_exit_edges_find (nodes, exit_edges)
9341 const sbitmap nodes;
9350 /* Check all nodes within the loop to see if there are any
9351 successors not in the loop. Note that a node may have multiple
9352 exiting edges ????? A node can have one jumping edge and one fallthru
9353 edge so only one of these can exit the loop. */
9355 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
9356 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
9358 basic_block dest = e->dest;
9360 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
9368 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
9370 /* Store all exiting edges into an array. */
9372 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
9373 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
9375 basic_block dest = e->dest;
9377 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
9378 (*exit_edges)[num_exits++] = e;
9386 /* Find the nodes contained within the loop with header HEADER and
9387 latch LATCH and store in NODES. Return the number of nodes within
9391 flow_loop_nodes_find (header, latch, nodes)
9400 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
9403 /* Start with only the loop header in the set of loop nodes. */
9404 sbitmap_zero (nodes);
9405 SET_BIT (nodes, header->index);
9407 header->loop_depth++;
9409 /* Push the loop latch on to the stack. */
9410 if (! TEST_BIT (nodes, latch->index))
9412 SET_BIT (nodes, latch->index);
9413 latch->loop_depth++;
9415 stack[sp++] = latch;
9424 for (e = node->pred; e; e = e->pred_next)
9426 basic_block ancestor = e->src;
9428 /* If each ancestor not marked as part of loop, add to set of
9429 loop nodes and push on to stack. */
9430 if (ancestor != ENTRY_BLOCK_PTR
9431 && ! TEST_BIT (nodes, ancestor->index))
9433 SET_BIT (nodes, ancestor->index);
9434 ancestor->loop_depth++;
9436 stack[sp++] = ancestor;
9444 /* Compute the depth first search order and store in the array
9445 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
9446 RC_ORDER is non-zero, return the reverse completion number for each
9447 node. Returns the number of nodes visited. A depth first search
9448 tries to get as far away from the starting point as quickly as
9452 flow_depth_first_order_compute (dfs_order, rc_order)
9459 int rcnum = n_basic_blocks - 1;
9462 /* Allocate stack for back-tracking up CFG. */
9463 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
9466 /* Allocate bitmap to track nodes that have been visited. */
9467 visited = sbitmap_alloc (n_basic_blocks);
9469 /* None of the nodes in the CFG have been visited yet. */
9470 sbitmap_zero (visited);
9472 /* Push the first edge on to the stack. */
9473 stack[sp++] = ENTRY_BLOCK_PTR->succ;
9481 /* Look at the edge on the top of the stack. */
9486 /* Check if the edge destination has been visited yet. */
9487 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
9489 /* Mark that we have visited the destination. */
9490 SET_BIT (visited, dest->index);
9493 dfs_order[dfsnum++] = dest->index;
9497 /* Since the DEST node has been visited for the first
9498 time, check its successors. */
9499 stack[sp++] = dest->succ;
9503 /* There are no successors for the DEST node so assign
9504 its reverse completion number. */
9506 rc_order[rcnum--] = dest->index;
9511 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
9513 /* There are no more successors for the SRC node
9514 so assign its reverse completion number. */
9516 rc_order[rcnum--] = src->index;
9520 stack[sp - 1] = e->succ_next;
9527 sbitmap_free (visited);
9529 /* The number of nodes visited should not be greater than
9531 if (dfsnum > n_basic_blocks)
9534 /* There are some nodes left in the CFG that are unreachable. */
9535 if (dfsnum < n_basic_blocks)
9540 /* Compute the depth first search order on the _reverse_ graph and
9541 store in the array DFS_ORDER, marking the nodes visited in VISITED.
9542 Returns the number of nodes visited.
9544 The computation is split into three pieces:
9546 flow_dfs_compute_reverse_init () creates the necessary data
9549 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
9550 structures. The block will start the search.
9552 flow_dfs_compute_reverse_execute () continues (or starts) the
9553 search using the block on the top of the stack, stopping when the
9556 flow_dfs_compute_reverse_finish () destroys the necessary data
9559 Thus, the user will probably call ..._init(), call ..._add_bb() to
9560 add a beginning basic block to the stack, call ..._execute(),
9561 possibly add another bb to the stack and again call ..._execute(),
9562 ..., and finally call _finish(). */
9564 /* Initialize the data structures used for depth-first search on the
9565 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
9566 added to the basic block stack. DATA is the current depth-first
9567 search context. If INITIALIZE_STACK is non-zero, there is an
9568 element on the stack. */
9571 flow_dfs_compute_reverse_init (data)
9572 depth_first_search_ds data;
9574 /* Allocate stack for back-tracking up CFG. */
9576 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
9577 * sizeof (basic_block));
9580 /* Allocate bitmap to track nodes that have been visited. */
9581 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
9583 /* None of the nodes in the CFG have been visited yet. */
9584 sbitmap_zero (data->visited_blocks);
9589 /* Add the specified basic block to the top of the dfs data
9590 structures. When the search continues, it will start at the
9594 flow_dfs_compute_reverse_add_bb (data, bb)
9595 depth_first_search_ds data;
9598 data->stack[data->sp++] = bb;
9602 /* Continue the depth-first search through the reverse graph starting
9603 with the block at the stack's top and ending when the stack is
9604 empty. Visited nodes are marked. Returns an unvisited basic
9605 block, or NULL if there is none available. */
9608 flow_dfs_compute_reverse_execute (data)
9609 depth_first_search_ds data;
9615 while (data->sp > 0)
9617 bb = data->stack[--data->sp];
9619 /* Mark that we have visited this node. */
9620 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
9622 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
9624 /* Perform depth-first search on adjacent vertices. */
9625 for (e = bb->pred; e; e = e->pred_next)
9626 flow_dfs_compute_reverse_add_bb (data, e->src);
9630 /* Determine if there are unvisited basic blocks. */
9631 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
9632 if (!TEST_BIT (data->visited_blocks, i))
9633 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
9637 /* Destroy the data structures needed for depth-first search on the
9641 flow_dfs_compute_reverse_finish (data)
9642 depth_first_search_ds data;
9645 sbitmap_free (data->visited_blocks);
9650 /* Find the root node of the loop pre-header extended basic block and
9651 the edges along the trace from the root node to the loop header. */
9654 flow_loop_pre_header_scan (loop)
9660 loop->num_pre_header_edges = 0;
9662 if (loop->num_entries != 1)
9665 ebb = loop->entry_edges[0]->src;
9667 if (ebb != ENTRY_BLOCK_PTR)
9671 /* Count number of edges along trace from loop header to
9672 root of pre-header extended basic block. Usually this is
9673 only one or two edges. */
9675 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
9677 ebb = ebb->pred->src;
9681 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
9682 loop->num_pre_header_edges = num;
9684 /* Store edges in order that they are followed. The source
9685 of the first edge is the root node of the pre-header extended
9686 basic block and the destination of the last last edge is
9688 for (e = loop->entry_edges[0]; num; e = e->src->pred)
9690 loop->pre_header_edges[--num] = e;
9696 /* Return the block for the pre-header of the loop with header
9697 HEADER where DOM specifies the dominator information. Return NULL if
9698 there is no pre-header. */
9701 flow_loop_pre_header_find (header, dom)
9705 basic_block pre_header;
9708 /* If block p is a predecessor of the header and is the only block
9709 that the header does not dominate, then it is the pre-header. */
9711 for (e = header->pred; e; e = e->pred_next)
9713 basic_block node = e->src;
9715 if (node != ENTRY_BLOCK_PTR
9716 && ! TEST_BIT (dom[node->index], header->index))
9718 if (pre_header == NULL)
9722 /* There are multiple edges into the header from outside
9723 the loop so there is no pre-header block. */
9732 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
9733 previously added. The insertion algorithm assumes that the loops
9734 are added in the order found by a depth first search of the CFG. */
9737 flow_loop_tree_node_add (prevloop, loop)
9738 struct loop *prevloop;
9742 if (flow_loop_nested_p (prevloop, loop))
9744 prevloop->inner = loop;
9745 loop->outer = prevloop;
9749 while (prevloop->outer)
9751 if (flow_loop_nested_p (prevloop->outer, loop))
9753 prevloop->next = loop;
9754 loop->outer = prevloop->outer;
9757 prevloop = prevloop->outer;
9760 prevloop->next = loop;
9764 /* Build the loop hierarchy tree for LOOPS. */
9767 flow_loops_tree_build (loops)
9768 struct loops *loops;
9773 num_loops = loops->num;
9777 /* Root the loop hierarchy tree with the first loop found.
9778 Since we used a depth first search this should be the
9780 loops->tree_root = &loops->array[0];
9781 loops->tree_root->outer = loops->tree_root->inner = loops->tree_root->next = NULL;
9783 /* Add the remaining loops to the tree. */
9784 for (i = 1; i < num_loops; i++)
9785 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
9788 /* Helper function to compute loop nesting depth and enclosed loop level
9789 for the natural loop specified by LOOP at the loop depth DEPTH.
9790 Returns the loop level. */
9793 flow_loop_level_compute (loop, depth)
9803 /* Traverse loop tree assigning depth and computing level as the
9804 maximum level of all the inner loops of this loop. The loop
9805 level is equivalent to the height of the loop in the loop tree
9806 and corresponds to the number of enclosed loop levels (including
9808 for (inner = loop->inner; inner; inner = inner->next)
9812 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
9817 loop->level = level;
9818 loop->depth = depth;
9822 /* Compute the loop nesting depth and enclosed loop level for the loop
9823 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
9827 flow_loops_level_compute (loops)
9828 struct loops *loops;
9834 /* Traverse all the outer level loops. */
9835 for (loop = loops->tree_root; loop; loop = loop->next)
9837 level = flow_loop_level_compute (loop, 1);
9845 /* Scan a single natural loop specified by LOOP collecting information
9846 about it specified by FLAGS. */
9849 flow_loop_scan (loops, loop, flags)
9850 struct loops *loops;
9854 /* Determine prerequisites. */
9855 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
9856 flags |= LOOP_EXIT_EDGES;
9858 if (flags & LOOP_ENTRY_EDGES)
9860 /* Find edges which enter the loop header.
9861 Note that the entry edges should only
9862 enter the header of a natural loop. */
9864 = flow_loop_entry_edges_find (loop->header,
9866 &loop->entry_edges);
9869 if (flags & LOOP_EXIT_EDGES)
9871 /* Find edges which exit the loop. */
9873 = flow_loop_exit_edges_find (loop->nodes,
9877 if (flags & LOOP_EXITS_DOMS)
9881 /* Determine which loop nodes dominate all the exits
9883 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
9884 sbitmap_copy (loop->exits_doms, loop->nodes);
9885 for (j = 0; j < loop->num_exits; j++)
9886 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
9887 loops->cfg.dom[loop->exit_edges[j]->src->index]);
9889 /* The header of a natural loop must dominate
9891 if (! TEST_BIT (loop->exits_doms, loop->header->index))
9895 if (flags & LOOP_PRE_HEADER)
9897 /* Look to see if the loop has a pre-header node. */
9899 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
9901 /* Find the blocks within the extended basic block of
9902 the loop pre-header. */
9903 flow_loop_pre_header_scan (loop);
9909 /* Find all the natural loops in the function and save in LOOPS structure
9910 and recalculate loop_depth information in basic block structures.
9911 FLAGS controls which loop information is collected.
9912 Return the number of natural loops found. */
9915 flow_loops_find (loops, flags)
9916 struct loops *loops;
9928 /* This function cannot be repeatedly called with different
9929 flags to build up the loop information. The loop tree
9930 must always be built if this function is called. */
9931 if (! (flags & LOOP_TREE))
9934 memset (loops, 0, sizeof (*loops));
9936 /* Taking care of this degenerate case makes the rest of
9937 this code simpler. */
9938 if (n_basic_blocks == 0)
9944 /* Compute the dominators. */
9945 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
9946 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
9948 /* Count the number of loop edges (back edges). This should be the
9949 same as the number of natural loops. */
9952 for (b = 0; b < n_basic_blocks; b++)
9956 header = BASIC_BLOCK (b);
9957 header->loop_depth = 0;
9959 for (e = header->pred; e; e = e->pred_next)
9961 basic_block latch = e->src;
9963 /* Look for back edges where a predecessor is dominated
9964 by this block. A natural loop has a single entry
9965 node (header) that dominates all the nodes in the
9966 loop. It also has single back edge to the header
9967 from a latch node. Note that multiple natural loops
9968 may share the same header. */
9969 if (b != header->index)
9972 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
9979 /* Compute depth first search order of the CFG so that outer
9980 natural loops will be found before inner natural loops. */
9981 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9982 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9983 flow_depth_first_order_compute (dfs_order, rc_order);
9985 /* Save CFG derived information to avoid recomputing it. */
9986 loops->cfg.dom = dom;
9987 loops->cfg.dfs_order = dfs_order;
9988 loops->cfg.rc_order = rc_order;
9990 /* Allocate loop structures. */
9992 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
9994 headers = sbitmap_alloc (n_basic_blocks);
9995 sbitmap_zero (headers);
9997 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
9998 sbitmap_zero (loops->shared_headers);
10000 /* Find and record information about all the natural loops
10003 for (b = 0; b < n_basic_blocks; b++)
10005 basic_block header;
10007 /* Search the nodes of the CFG in reverse completion order
10008 so that we can find outer loops first. */
10009 header = BASIC_BLOCK (rc_order[b]);
10011 /* Look for all the possible latch blocks for this header. */
10012 for (e = header->pred; e; e = e->pred_next)
10014 basic_block latch = e->src;
10016 /* Look for back edges where a predecessor is dominated
10017 by this block. A natural loop has a single entry
10018 node (header) that dominates all the nodes in the
10019 loop. It also has single back edge to the header
10020 from a latch node. Note that multiple natural loops
10021 may share the same header. */
10022 if (latch != ENTRY_BLOCK_PTR
10023 && TEST_BIT (dom[latch->index], header->index))
10027 loop = loops->array + num_loops;
10029 loop->header = header;
10030 loop->latch = latch;
10031 loop->num = num_loops;
10038 for (i = 0; i < num_loops; i++)
10040 struct loop *loop = &loops->array[i];
10042 /* Keep track of blocks that are loop headers so
10043 that we can tell which loops should be merged. */
10044 if (TEST_BIT (headers, loop->header->index))
10045 SET_BIT (loops->shared_headers, loop->header->index);
10046 SET_BIT (headers, loop->header->index);
10048 /* Find nodes contained within the loop. */
10049 loop->nodes = sbitmap_alloc (n_basic_blocks);
10051 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
10053 /* Compute first and last blocks within the loop.
10054 These are often the same as the loop header and
10055 loop latch respectively, but this is not always
10058 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
10060 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
10062 flow_loop_scan (loops, loop, flags);
10065 /* Natural loops with shared headers may either be disjoint or
10066 nested. Disjoint loops with shared headers cannot be inner
10067 loops and should be merged. For now just mark loops that share
10069 for (i = 0; i < num_loops; i++)
10070 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
10071 loops->array[i].shared = 1;
10073 sbitmap_free (headers);
10077 sbitmap_vector_free (dom);
10080 loops->num = num_loops;
10082 /* Build the loop hierarchy tree. */
10083 flow_loops_tree_build (loops);
10085 /* Assign the loop nesting depth and enclosed loop level for each
10087 loops->levels = flow_loops_level_compute (loops);
10093 /* Update the information regarding the loops in the CFG
10094 specified by LOOPS. */
10096 flow_loops_update (loops, flags)
10097 struct loops *loops;
10100 /* One day we may want to update the current loop data. For now
10101 throw away the old stuff and rebuild what we need. */
10103 flow_loops_free (loops);
10105 return flow_loops_find (loops, flags);
10109 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
10112 flow_loop_outside_edge_p (loop, e)
10113 const struct loop *loop;
10116 if (e->dest != loop->header)
10118 return (e->src == ENTRY_BLOCK_PTR)
10119 || ! TEST_BIT (loop->nodes, e->src->index);
10122 /* Clear LOG_LINKS fields of insns in a chain.
10123 Also clear the global_live_at_{start,end} fields of the basic block
10127 clear_log_links (insns)
10133 for (i = insns; i; i = NEXT_INSN (i))
10137 for (b = 0; b < n_basic_blocks; b++)
10139 basic_block bb = BASIC_BLOCK (b);
10141 bb->global_live_at_start = NULL;
10142 bb->global_live_at_end = NULL;
10145 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
10146 EXIT_BLOCK_PTR->global_live_at_start = NULL;
10149 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
10150 correspond to the hard registers, if any, set in that map. This
10151 could be done far more efficiently by having all sorts of special-cases
10152 with moving single words, but probably isn't worth the trouble. */
10155 reg_set_to_hard_reg_set (to, from)
10161 EXECUTE_IF_SET_IN_BITMAP
10164 if (i >= FIRST_PSEUDO_REGISTER)
10166 SET_HARD_REG_BIT (*to, i);
10170 /* Called once at intialization time. */
10175 static int initialized;
10179 gcc_obstack_init (&flow_obstack);
10180 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
10185 obstack_free (&flow_obstack, flow_firstobj);
10186 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
10190 /* Assume that the preceeding pass has possibly eliminated jump instructions
10191 or converted the unconditional jumps. Eliminate the edges from CFG.
10192 Return true if any edges are eliminated. */
10195 purge_dead_edges (bb)
10199 rtx insn = bb->end;
10200 bool purged = false;
10202 if (GET_CODE (insn) == JUMP_INSN && !simplejump_p (insn))
10204 if (GET_CODE (insn) == JUMP_INSN)
10208 /* We do care only about conditional jumps and simplejumps. */
10209 if (!any_condjump_p (insn)
10210 && !returnjump_p (insn)
10211 && !simplejump_p (insn))
10213 for (e = bb->succ; e; e = next)
10215 next = e->succ_next;
10217 /* Check purposes we can have edge. */
10218 if ((e->flags & EDGE_FALLTHRU)
10219 && any_condjump_p (insn))
10221 if (e->dest != EXIT_BLOCK_PTR
10222 && e->dest->head == JUMP_LABEL (insn))
10224 if (e->dest == EXIT_BLOCK_PTR
10225 && returnjump_p (insn))
10230 if (!bb->succ || !purged)
10233 fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
10237 /* Redistribute probabilities. */
10238 if (!bb->succ->succ_next)
10240 bb->succ->probability = REG_BR_PROB_BASE;
10241 bb->succ->count = bb->count;
10245 note = find_reg_note (insn, REG_BR_PROB, NULL);
10248 b = BRANCH_EDGE (bb);
10249 f = FALLTHRU_EDGE (bb);
10250 b->probability = INTVAL (XEXP (note, 0));
10251 f->probability = REG_BR_PROB_BASE - b->probability;
10252 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
10253 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
10258 /* Cleanup abnormal edges caused by throwing insns that have been
10260 if (! can_throw_internal (bb->end))
10261 for (e = bb->succ; e; e = next)
10263 next = e->succ_next;
10264 if (e->flags & EDGE_EH)
10271 /* If we don't see a jump insn, we don't know exactly why the block would
10272 have been broken at this point. Look for a simple, non-fallthru edge,
10273 as these are only created by conditional branches. If we find such an
10274 edge we know that there used to be a jump here and can then safely
10275 remove all non-fallthru edges. */
10276 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
10280 for (e = bb->succ; e; e = next)
10282 next = e->succ_next;
10283 if (!(e->flags & EDGE_FALLTHRU))
10284 remove_edge (e), purged = true;
10286 if (!bb->succ || bb->succ->succ_next)
10288 bb->succ->probability = REG_BR_PROB_BASE;
10289 bb->succ->count = bb->count;
10292 fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n",
10297 /* Search all basic blocks for potentionally dead edges and purge them.
10299 Return true ifif some edge has been elliminated.
10303 purge_all_dead_edges ()
10305 int i, purged = false;
10306 for (i = 0; i < n_basic_blocks; i++)
10307 purged |= purge_dead_edges (BASIC_BLOCK (i));