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 ((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 invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
454 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
456 static void remove_fake_successors PARAMS ((basic_block));
457 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
459 static void flow_edge_list_print PARAMS ((const char *, const edge *,
461 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
463 static int flow_loop_nested_p PARAMS ((struct loop *,
465 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
467 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
468 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
469 static void flow_dfs_compute_reverse_init
470 PARAMS ((depth_first_search_ds));
471 static void flow_dfs_compute_reverse_add_bb
472 PARAMS ((depth_first_search_ds, basic_block));
473 static basic_block flow_dfs_compute_reverse_execute
474 PARAMS ((depth_first_search_ds));
475 static void flow_dfs_compute_reverse_finish
476 PARAMS ((depth_first_search_ds));
477 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
478 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
480 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
481 static void flow_loops_tree_build PARAMS ((struct loops *));
482 static int flow_loop_level_compute PARAMS ((struct loop *, int));
483 static int flow_loops_level_compute PARAMS ((struct loops *));
484 static void delete_dead_jumptables PARAMS ((void));
485 static bool back_edge_of_syntactic_loop_p PARAMS ((basic_block, basic_block));
487 /* Find basic blocks of the current function.
488 F is the first insn of the function and NREGS the number of register
492 find_basic_blocks (f, nregs, file)
494 int nregs ATTRIBUTE_UNUSED;
495 FILE *file ATTRIBUTE_UNUSED;
498 timevar_push (TV_CFG);
500 /* Flush out existing data. */
501 if (basic_block_info != NULL)
507 /* Clear bb->aux on all extant basic blocks. We'll use this as a
508 tag for reuse during create_basic_block, just in case some pass
509 copies around basic block notes improperly. */
510 for (i = 0; i < n_basic_blocks; ++i)
511 BASIC_BLOCK (i)->aux = NULL;
513 VARRAY_FREE (basic_block_info);
516 n_basic_blocks = count_basic_blocks (f);
518 /* Size the basic block table. The actual structures will be allocated
519 by find_basic_blocks_1, since we want to keep the structure pointers
520 stable across calls to find_basic_blocks. */
521 /* ??? This whole issue would be much simpler if we called find_basic_blocks
522 exactly once, and thereafter we don't have a single long chain of
523 instructions at all until close to the end of compilation when we
524 actually lay them out. */
526 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
528 find_basic_blocks_1 (f);
530 /* Record the block to which an insn belongs. */
531 /* ??? This should be done another way, by which (perhaps) a label is
532 tagged directly with the basic block that it starts. It is used for
533 more than that currently, but IMO that is the only valid use. */
535 max_uid = get_max_uid ();
537 /* Leave space for insns life_analysis makes in some cases for auto-inc.
538 These cases are rare, so we don't need too much space. */
539 max_uid += max_uid / 10;
542 compute_bb_for_insn (max_uid);
544 /* Discover the edges of our cfg. */
545 make_edges (label_value_list, 0, n_basic_blocks - 1, 0);
547 /* Do very simple cleanup now, for the benefit of code that runs between
548 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
549 tidy_fallthru_edges ();
551 mark_critical_edges ();
553 #ifdef ENABLE_CHECKING
556 timevar_pop (TV_CFG);
560 check_function_return_warnings ()
562 if (warn_missing_noreturn
563 && !TREE_THIS_VOLATILE (cfun->decl)
564 && EXIT_BLOCK_PTR->pred == NULL
565 && (lang_missing_noreturn_ok_p
566 && !lang_missing_noreturn_ok_p (cfun->decl)))
567 warning ("function might be possible candidate for attribute `noreturn'");
569 /* If we have a path to EXIT, then we do return. */
570 if (TREE_THIS_VOLATILE (cfun->decl)
571 && EXIT_BLOCK_PTR->pred != NULL)
572 warning ("`noreturn' function does return");
574 /* If the clobber_return_insn appears in some basic block, then we
575 do reach the end without returning a value. */
576 else if (warn_return_type
577 && cfun->x_clobber_return_insn != NULL
578 && EXIT_BLOCK_PTR->pred != NULL)
580 int max_uid = get_max_uid ();
582 /* If clobber_return_insn was excised by jump1, then renumber_insns
583 can make max_uid smaller than the number still recorded in our rtx.
584 That's fine, since this is a quick way of verifying that the insn
585 is no longer in the chain. */
586 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
588 /* Recompute insn->block mapping, since the initial mapping is
589 set before we delete unreachable blocks. */
590 compute_bb_for_insn (max_uid);
592 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
593 warning ("control reaches end of non-void function");
598 /* Count the basic blocks of the function. */
601 count_basic_blocks (f)
605 register RTX_CODE prev_code;
606 register int count = 0;
607 int saw_abnormal_edge = 0;
609 prev_code = JUMP_INSN;
610 for (insn = f; insn; insn = NEXT_INSN (insn))
612 enum rtx_code code = GET_CODE (insn);
614 if (code == CODE_LABEL
615 || (GET_RTX_CLASS (code) == 'i'
616 && (prev_code == JUMP_INSN
617 || prev_code == BARRIER
618 || saw_abnormal_edge)))
620 saw_abnormal_edge = 0;
624 /* Record whether this insn created an edge. */
625 if (code == CALL_INSN)
629 /* If there is a nonlocal goto label and the specified
630 region number isn't -1, we have an edge. */
631 if (nonlocal_goto_handler_labels
632 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
633 || INTVAL (XEXP (note, 0)) >= 0))
634 saw_abnormal_edge = 1;
636 else if (can_throw_internal (insn))
637 saw_abnormal_edge = 1;
639 else if (flag_non_call_exceptions
641 && can_throw_internal (insn))
642 saw_abnormal_edge = 1;
648 /* The rest of the compiler works a bit smoother when we don't have to
649 check for the edge case of do-nothing functions with no basic blocks. */
652 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
659 /* Scan a list of insns for labels referred to other than by jumps.
660 This is used to scan the alternatives of a call placeholder. */
662 find_label_refs (f, lvl)
668 for (insn = f; insn; insn = NEXT_INSN (insn))
669 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
673 /* Make a list of all labels referred to other than by jumps
674 (which just don't have the REG_LABEL notes).
676 Make a special exception for labels followed by an ADDR*VEC,
677 as this would be a part of the tablejump setup code.
679 Make a special exception to registers loaded with label
680 values just before jump insns that use them. */
682 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
683 if (REG_NOTE_KIND (note) == REG_LABEL)
685 rtx lab = XEXP (note, 0), next;
687 if ((next = next_nonnote_insn (lab)) != NULL
688 && GET_CODE (next) == JUMP_INSN
689 && (GET_CODE (PATTERN (next)) == ADDR_VEC
690 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
692 else if (GET_CODE (lab) == NOTE)
694 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
695 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
698 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
705 /* Assume that someone emitted code with control flow instructions to the
706 basic block. Update the data structure. */
708 find_sub_basic_blocks (bb)
713 rtx jump_insn = NULL_RTX;
715 basic_block first_bb = bb;
721 if (GET_CODE (insn) == CODE_LABEL)
722 insn = NEXT_INSN (insn);
724 /* Scan insn chain and try to find new basic block boundaries. */
727 enum rtx_code code = GET_CODE (insn);
734 /* On code label, split current basic block. */
736 falltru = split_block (bb, PREV_INSN (insn));
740 remove_edge (falltru);
742 if (LABEL_ALTERNATE_NAME (insn))
743 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
747 /* In case we've previously split insn on the JUMP_INSN, move the
748 block header to proper place. */
751 falltru = split_block (bb, PREV_INSN (insn));
754 remove_edge (falltru);
757 /* We need some special care for those expressions. */
758 if (GET_CODE (insn) == JUMP_INSN)
760 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
761 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
771 insn = NEXT_INSN (insn);
774 /* In case expander replaced normal insn by sequence terminating by
775 return and barrier, or possibly other sequence not behaving like
776 ordinary jump, we need to take care and move basic block boundary. */
777 if (jump_insn && GET_CODE (bb->end) != JUMP_INSN)
780 /* We've possibly replaced the conditional jump by conditional jump
781 followed by cleanup at fallthru edge, so the outgoing edges may
783 purge_dead_edges (bb);
785 /* Now re-scan and wire in all edges. This expect simple (conditional)
786 jumps at the end of each new basic blocks. */
787 make_edges (NULL, first_bb->index, bb->index, 1);
789 /* Update branch probabilities. Expect only (un)conditional jumps
790 to be created with only the forward edges. */
791 for (i = first_bb->index; i <= bb->index; i++)
794 basic_block b = BASIC_BLOCK (i);
799 for (e = b->pred; e; e=e->pred_next)
801 b->count += e->count;
802 b->frequency += EDGE_FREQUENCY (e);
805 if (b->succ && b->succ->succ_next && !b->succ->succ_next->succ_next)
807 rtx note = find_reg_note (b->end, REG_BR_PROB, NULL);
812 probability = INTVAL (XEXP (find_reg_note (b->end,
816 e->probability = probability;
817 e->count = ((b->count * probability + REG_BR_PROB_BASE / 2)
819 f = FALLTHRU_EDGE (b);
820 f->probability = REG_BR_PROB_BASE - probability;
821 f->count = b->count - e->count;
823 if (b->succ && !b->succ->succ_next)
826 e->probability = REG_BR_PROB_BASE;
832 /* Find all basic blocks of the function whose first insn is F.
834 Collect and return a list of labels whose addresses are taken. This
835 will be used in make_edges for use with computed gotos. */
838 find_basic_blocks_1 (f)
841 register rtx insn, next;
843 rtx bb_note = NULL_RTX;
849 /* We process the instructions in a slightly different way than we did
850 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
851 closed out the previous block, so that it gets attached at the proper
852 place. Since this form should be equivalent to the previous,
853 count_basic_blocks continues to use the old form as a check. */
855 for (insn = f; insn; insn = next)
857 enum rtx_code code = GET_CODE (insn);
859 next = NEXT_INSN (insn);
865 int kind = NOTE_LINE_NUMBER (insn);
867 /* Look for basic block notes with which to keep the
868 basic_block_info pointers stable. Unthread the note now;
869 we'll put it back at the right place in create_basic_block.
870 Or not at all if we've already found a note in this block. */
871 if (kind == NOTE_INSN_BASIC_BLOCK)
873 if (bb_note == NULL_RTX)
876 next = flow_delete_insn (insn);
882 /* A basic block starts at a label. If we've closed one off due
883 to a barrier or some such, no need to do it again. */
884 if (head != NULL_RTX)
886 create_basic_block (i++, head, end, bb_note);
894 /* A basic block ends at a jump. */
895 if (head == NULL_RTX)
899 /* ??? Make a special check for table jumps. The way this
900 happens is truly and amazingly gross. We are about to
901 create a basic block that contains just a code label and
902 an addr*vec jump insn. Worse, an addr_diff_vec creates
903 its own natural loop.
905 Prevent this bit of brain damage, pasting things together
906 correctly in make_edges.
908 The correct solution involves emitting the table directly
909 on the tablejump instruction as a note, or JUMP_LABEL. */
911 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
912 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
920 goto new_bb_inclusive;
923 /* A basic block ends at a barrier. It may be that an unconditional
924 jump already closed the basic block -- no need to do it again. */
925 if (head == NULL_RTX)
927 goto new_bb_exclusive;
931 /* Record whether this call created an edge. */
932 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
933 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
935 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
937 /* Scan each of the alternatives for label refs. */
938 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
939 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
940 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
941 /* Record its tail recursion label, if any. */
942 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
943 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
946 /* A basic block ends at a call that can either throw or
947 do a non-local goto. */
948 if ((nonlocal_goto_handler_labels && region >= 0)
949 || can_throw_internal (insn))
952 if (head == NULL_RTX)
957 create_basic_block (i++, head, end, bb_note);
958 head = end = NULL_RTX;
966 /* Non-call exceptions generate new blocks just like calls. */
967 if (flag_non_call_exceptions && can_throw_internal (insn))
968 goto new_bb_inclusive;
970 if (head == NULL_RTX)
979 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
983 /* Make a list of all labels referred to other than by jumps.
985 Make a special exception for labels followed by an ADDR*VEC,
986 as this would be a part of the tablejump setup code.
988 Make a special exception to registers loaded with label
989 values just before jump insns that use them. */
991 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
992 if (REG_NOTE_KIND (note) == REG_LABEL)
994 rtx lab = XEXP (note, 0), next;
996 if ((next = next_nonnote_insn (lab)) != NULL
997 && GET_CODE (next) == JUMP_INSN
998 && (GET_CODE (PATTERN (next)) == ADDR_VEC
999 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1001 else if (GET_CODE (lab) == NOTE)
1003 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
1004 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
1007 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
1012 if (head != NULL_RTX)
1013 create_basic_block (i++, head, end, bb_note);
1015 flow_delete_insn (bb_note);
1017 if (i != n_basic_blocks)
1020 label_value_list = lvl;
1021 tail_recursion_label_list = trll;
1024 /* Tidy the CFG by deleting unreachable code and whatnot. */
1030 timevar_push (TV_CLEANUP_CFG);
1031 delete_unreachable_blocks ();
1032 if (try_optimize_cfg (mode))
1033 delete_unreachable_blocks ();
1034 mark_critical_edges ();
1036 /* Kill the data we won't maintain. */
1037 free_EXPR_LIST_list (&label_value_list);
1038 free_EXPR_LIST_list (&tail_recursion_label_list);
1039 timevar_pop (TV_CLEANUP_CFG);
1042 /* Create a new basic block consisting of the instructions between
1043 HEAD and END inclusive. Reuses the note and basic block struct
1044 in BB_NOTE, if any. */
1047 create_basic_block (index, head, end, bb_note)
1049 rtx head, end, bb_note;
1054 && ! RTX_INTEGRATED_P (bb_note)
1055 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1058 /* If we found an existing note, thread it back onto the chain. */
1062 if (GET_CODE (head) == CODE_LABEL)
1066 after = PREV_INSN (head);
1070 if (after != bb_note && NEXT_INSN (after) != bb_note)
1071 reorder_insns (bb_note, bb_note, after);
1075 /* Otherwise we must create a note and a basic block structure.
1076 Since we allow basic block structs in rtl, give the struct
1077 the same lifetime by allocating it off the function obstack
1078 rather than using malloc. */
1080 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1081 memset (bb, 0, sizeof (*bb));
1083 if (GET_CODE (head) == CODE_LABEL)
1084 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1087 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1090 NOTE_BASIC_BLOCK (bb_note) = bb;
1093 /* Always include the bb note in the block. */
1094 if (NEXT_INSN (end) == bb_note)
1100 BASIC_BLOCK (index) = bb;
1102 /* Tag the block so that we know it has been used when considering
1103 other basic block notes. */
1107 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
1108 note associated with the BLOCK. */
1111 first_insn_after_basic_block_note (block)
1116 /* Get the first instruction in the block. */
1119 if (insn == NULL_RTX)
1121 if (GET_CODE (insn) == CODE_LABEL)
1122 insn = NEXT_INSN (insn);
1123 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
1126 return NEXT_INSN (insn);
1129 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1130 indexed by INSN_UID. MAX is the size of the array. */
1133 compute_bb_for_insn (max)
1138 if (basic_block_for_insn)
1139 VARRAY_FREE (basic_block_for_insn);
1140 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1142 for (i = 0; i < n_basic_blocks; ++i)
1144 basic_block bb = BASIC_BLOCK (i);
1151 int uid = INSN_UID (insn);
1153 VARRAY_BB (basic_block_for_insn, uid) = bb;
1156 insn = NEXT_INSN (insn);
1161 /* Free the memory associated with the edge structures. */
1169 for (i = 0; i < n_basic_blocks; ++i)
1171 basic_block bb = BASIC_BLOCK (i);
1173 for (e = bb->succ; e; e = n)
1183 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1189 ENTRY_BLOCK_PTR->succ = 0;
1190 EXIT_BLOCK_PTR->pred = 0;
1195 /* Identify the edges between basic blocks MIN to MAX.
1197 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1198 that are otherwise unreachable may be reachable with a non-local goto.
1200 BB_EH_END is an array indexed by basic block number in which we record
1201 the list of exception regions active at the end of the basic block. */
1204 make_edges (label_value_list, min, max, update_p)
1205 rtx label_value_list;
1206 int min, max, update_p;
1209 sbitmap *edge_cache = NULL;
1211 /* Assume no computed jump; revise as we create edges. */
1212 current_function_has_computed_jump = 0;
1214 /* Heavy use of computed goto in machine-generated code can lead to
1215 nearly fully-connected CFGs. In that case we spend a significant
1216 amount of time searching the edge lists for duplicates. */
1217 if (forced_labels || label_value_list)
1219 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1220 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1223 for (i = min; i <= max; ++i)
1226 for (e = BASIC_BLOCK (i)->succ; e ; e = e->succ_next)
1227 if (e->dest != EXIT_BLOCK_PTR)
1228 SET_BIT (edge_cache[i], e->dest->index);
1232 /* By nature of the way these get numbered, block 0 is always the entry. */
1233 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1235 for (i = min; i <= max; ++i)
1237 basic_block bb = BASIC_BLOCK (i);
1240 int force_fallthru = 0;
1242 if (GET_CODE (bb->head) == CODE_LABEL
1243 && LABEL_ALTERNATE_NAME (bb->head))
1244 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1246 /* Examine the last instruction of the block, and discover the
1247 ways we can leave the block. */
1250 code = GET_CODE (insn);
1253 if (code == JUMP_INSN)
1257 /* Recognize exception handling placeholders. */
1258 if (GET_CODE (PATTERN (insn)) == RESX)
1259 make_eh_edge (edge_cache, bb, insn);
1261 /* Recognize a non-local goto as a branch outside the
1262 current function. */
1263 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1266 /* ??? Recognize a tablejump and do the right thing. */
1267 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1268 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1269 && GET_CODE (tmp) == JUMP_INSN
1270 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1271 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1276 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1277 vec = XVEC (PATTERN (tmp), 0);
1279 vec = XVEC (PATTERN (tmp), 1);
1281 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1282 make_label_edge (edge_cache, bb,
1283 XEXP (RTVEC_ELT (vec, j), 0), 0);
1285 /* Some targets (eg, ARM) emit a conditional jump that also
1286 contains the out-of-range target. Scan for these and
1287 add an edge if necessary. */
1288 if ((tmp = single_set (insn)) != NULL
1289 && SET_DEST (tmp) == pc_rtx
1290 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1291 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1292 make_label_edge (edge_cache, bb,
1293 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1295 #ifdef CASE_DROPS_THROUGH
1296 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1297 us naturally detecting fallthru into the next block. */
1302 /* If this is a computed jump, then mark it as reaching
1303 everything on the label_value_list and forced_labels list. */
1304 else if (computed_jump_p (insn))
1306 current_function_has_computed_jump = 1;
1308 for (x = label_value_list; x; x = XEXP (x, 1))
1309 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1311 for (x = forced_labels; x; x = XEXP (x, 1))
1312 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1315 /* Returns create an exit out. */
1316 else if (returnjump_p (insn))
1317 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1319 /* Otherwise, we have a plain conditional or unconditional jump. */
1322 if (! JUMP_LABEL (insn))
1324 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1328 /* If this is a sibling call insn, then this is in effect a
1329 combined call and return, and so we need an edge to the
1330 exit block. No need to worry about EH edges, since we
1331 wouldn't have created the sibling call in the first place. */
1333 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1334 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1335 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1337 /* If this is a CALL_INSN, then mark it as reaching the active EH
1338 handler for this CALL_INSN. If we're handling non-call
1339 exceptions then any insn can reach any of the active handlers.
1341 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1343 else if (code == CALL_INSN || flag_non_call_exceptions)
1345 /* Add any appropriate EH edges. */
1346 make_eh_edge (edge_cache, bb, insn);
1348 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1350 /* ??? This could be made smarter: in some cases it's possible
1351 to tell that certain calls will not do a nonlocal goto.
1353 For example, if the nested functions that do the nonlocal
1354 gotos do not have their addresses taken, then only calls to
1355 those functions or to other nested functions that use them
1356 could possibly do nonlocal gotos. */
1357 /* We do know that a REG_EH_REGION note with a value less
1358 than 0 is guaranteed not to perform a non-local goto. */
1359 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1360 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1361 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1362 make_label_edge (edge_cache, bb, XEXP (x, 0),
1363 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1367 /* Find out if we can drop through to the next block. */
1368 insn = next_nonnote_insn (insn);
1369 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1370 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1371 else if (i + 1 < n_basic_blocks)
1373 rtx tmp = BLOCK_HEAD (i + 1);
1374 if (GET_CODE (tmp) == NOTE)
1375 tmp = next_nonnote_insn (tmp);
1376 if (force_fallthru || insn == tmp)
1377 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1382 sbitmap_vector_free (edge_cache);
1385 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1386 about the edge that is accumulated between calls. */
1389 make_edge (edge_cache, src, dst, flags)
1390 sbitmap *edge_cache;
1391 basic_block src, dst;
1397 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1398 many edges to them, and we didn't allocate memory for it. */
1399 use_edge_cache = (edge_cache
1400 && src != ENTRY_BLOCK_PTR
1401 && dst != EXIT_BLOCK_PTR);
1403 /* Make sure we don't add duplicate edges. */
1404 switch (use_edge_cache)
1407 /* Quick test for non-existance of the edge. */
1408 if (! TEST_BIT (edge_cache[src->index], dst->index))
1411 /* The edge exists; early exit if no work to do. */
1417 for (e = src->succ; e; e = e->succ_next)
1426 e = (edge) xcalloc (1, sizeof (*e));
1429 e->succ_next = src->succ;
1430 e->pred_next = dst->pred;
1439 SET_BIT (edge_cache[src->index], dst->index);
1442 /* Create an edge from a basic block to a label. */
1445 make_label_edge (edge_cache, src, label, flags)
1446 sbitmap *edge_cache;
1451 if (GET_CODE (label) != CODE_LABEL)
1454 /* If the label was never emitted, this insn is junk, but avoid a
1455 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1456 as a result of a syntax error and a diagnostic has already been
1459 if (INSN_UID (label) == 0)
1462 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1465 /* Create the edges generated by INSN in REGION. */
1468 make_eh_edge (edge_cache, src, insn)
1469 sbitmap *edge_cache;
1473 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1476 handlers = reachable_handlers (insn);
1478 for (i = handlers; i; i = XEXP (i, 1))
1479 make_label_edge (edge_cache, src, XEXP (i, 0),
1480 EDGE_ABNORMAL | EDGE_EH | is_call);
1482 free_INSN_LIST_list (&handlers);
1485 /* Identify critical edges and set the bits appropriately. */
1488 mark_critical_edges ()
1490 int i, n = n_basic_blocks;
1493 /* We begin with the entry block. This is not terribly important now,
1494 but could be if a front end (Fortran) implemented alternate entry
1496 bb = ENTRY_BLOCK_PTR;
1503 /* (1) Critical edges must have a source with multiple successors. */
1504 if (bb->succ && bb->succ->succ_next)
1506 for (e = bb->succ; e; e = e->succ_next)
1508 /* (2) Critical edges must have a destination with multiple
1509 predecessors. Note that we know there is at least one
1510 predecessor -- the edge we followed to get here. */
1511 if (e->dest->pred->pred_next)
1512 e->flags |= EDGE_CRITICAL;
1514 e->flags &= ~EDGE_CRITICAL;
1519 for (e = bb->succ; e; e = e->succ_next)
1520 e->flags &= ~EDGE_CRITICAL;
1525 bb = BASIC_BLOCK (i);
1529 /* Split a block BB after insn INSN creating a new fallthru edge.
1530 Return the new edge. Note that to keep other parts of the compiler happy,
1531 this function renumbers all the basic blocks so that the new
1532 one has a number one greater than the block split. */
1535 split_block (bb, insn)
1545 /* There is no point splitting the block after its end. */
1546 if (bb->end == insn)
1549 /* Create the new structures. */
1550 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1551 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1554 memset (new_bb, 0, sizeof (*new_bb));
1556 new_bb->head = NEXT_INSN (insn);
1557 new_bb->end = bb->end;
1560 new_bb->succ = bb->succ;
1561 bb->succ = new_edge;
1562 new_bb->pred = new_edge;
1563 new_bb->count = bb->count;
1564 new_bb->frequency = bb->frequency;
1565 new_bb->loop_depth = bb->loop_depth;
1568 new_edge->dest = new_bb;
1569 new_edge->flags = EDGE_FALLTHRU;
1570 new_edge->probability = REG_BR_PROB_BASE;
1571 new_edge->count = bb->count;
1573 /* Redirect the src of the successor edges of bb to point to new_bb. */
1574 for (e = new_bb->succ; e; e = e->succ_next)
1577 /* Place the new block just after the block being split. */
1578 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1580 /* Some parts of the compiler expect blocks to be number in
1581 sequential order so insert the new block immediately after the
1582 block being split.. */
1584 for (i = n_basic_blocks - 1; i > j + 1; --i)
1586 basic_block tmp = BASIC_BLOCK (i - 1);
1587 BASIC_BLOCK (i) = tmp;
1591 BASIC_BLOCK (i) = new_bb;
1594 if (GET_CODE (new_bb->head) == CODE_LABEL)
1596 /* Create the basic block note. */
1597 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1599 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1601 /* If the only thing in this new block was the label, make sure
1602 the block note gets included. */
1603 if (new_bb->head == new_bb->end)
1604 new_bb->end = bb_note;
1608 /* Create the basic block note. */
1609 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1611 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1612 new_bb->head = bb_note;
1615 update_bb_for_insn (new_bb);
1617 if (bb->global_live_at_start)
1619 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1620 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1621 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1623 /* We now have to calculate which registers are live at the end
1624 of the split basic block and at the start of the new basic
1625 block. Start with those registers that are known to be live
1626 at the end of the original basic block and get
1627 propagate_block to determine which registers are live. */
1628 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1629 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1630 COPY_REG_SET (bb->global_live_at_end,
1631 new_bb->global_live_at_start);
1637 /* Return label in the head of basic block. Create one if it doesn't exist. */
1642 if (block == EXIT_BLOCK_PTR)
1644 if (GET_CODE (block->head) != CODE_LABEL)
1646 block->head = emit_label_before (gen_label_rtx (), block->head);
1647 if (basic_block_for_insn)
1648 set_block_for_insn (block->head, block);
1653 /* Return true if the block has no effect and only forwards control flow to
1654 its single destination. */
1656 forwarder_block_p (bb)
1659 rtx insn = bb->head;
1660 if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
1661 || !bb->succ || bb->succ->succ_next)
1664 while (insn != bb->end)
1666 if (active_insn_p (insn))
1668 insn = NEXT_INSN (insn);
1670 return (!active_insn_p (insn)
1671 || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)));
1674 /* Return nonzero if we can reach target from src by falling trought. */
1676 can_fallthru (src, target)
1677 basic_block src, target;
1679 rtx insn = src->end;
1680 rtx insn2 = target->head;
1682 if (src->index + 1 == target->index && !active_insn_p (insn2))
1683 insn2 = next_active_insn (insn2);
1684 /* ??? Later we may add code to move jump tables offline. */
1685 return next_active_insn (insn) == insn2;
1688 /* Attempt to perform edge redirection by replacing possibly complex jump
1689 instruction by unconditional jump or removing jump completely.
1690 This can apply only if all edges now point to the same block.
1692 The parameters and return values are equivalent to redirect_edge_and_branch.
1695 try_redirect_by_replacing_jump (e, target)
1699 basic_block src = e->src;
1700 rtx insn = src->end, kill_from;
1705 /* Verify that all targets will be TARGET. */
1706 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
1707 if (tmp->dest != target && tmp != e)
1709 if (tmp || !onlyjump_p (insn))
1712 /* Avoid removing branch with side effects. */
1713 set = single_set (insn);
1714 if (!set || side_effects_p (set))
1717 /* In case we zap a conditional jump, we'll need to kill
1718 the cc0 setter too. */
1721 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
1722 kill_from = PREV_INSN (insn);
1725 /* See if we can create the fallthru edge. */
1726 if (can_fallthru (src, target))
1728 src->end = PREV_INSN (kill_from);
1730 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
1733 /* Selectivly unlink whole insn chain. */
1734 flow_delete_insn_chain (kill_from, PREV_INSN (target->head));
1736 /* If this already is simplejump, redirect it. */
1737 else if (simplejump_p (insn))
1739 if (e->dest == target)
1742 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
1743 INSN_UID (insn), e->dest->index, target->index);
1744 redirect_jump (insn, block_label (target), 0);
1746 /* Or replace possibly complicated jump insn by simple jump insn. */
1749 rtx target_label = block_label (target);
1752 src->end = emit_jump_insn_before (gen_jump (target_label), kill_from);
1753 JUMP_LABEL (src->end) = target_label;
1754 LABEL_NUSES (target_label)++;
1755 if (basic_block_for_insn)
1756 set_block_for_new_insns (src->end, src);
1758 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
1759 INSN_UID (insn), INSN_UID (src->end));
1761 flow_delete_insn_chain (kill_from, insn);
1763 barrier = next_nonnote_insn (src->end);
1764 if (!barrier || GET_CODE (barrier) != BARRIER)
1765 emit_barrier_after (src->end);
1768 /* Keep only one edge out and set proper flags. */
1769 while (src->succ->succ_next)
1770 remove_edge (src->succ);
1773 e->flags = EDGE_FALLTHRU;
1776 e->probability = REG_BR_PROB_BASE;
1777 e->count = src->count;
1779 /* We don't want a block to end on a line-number note since that has
1780 the potential of changing the code between -g and not -g. */
1781 while (GET_CODE (e->src->end) == NOTE
1782 && NOTE_LINE_NUMBER (e->src->end) >= 0)
1784 rtx prev = PREV_INSN (e->src->end);
1785 flow_delete_insn (e->src->end);
1789 if (e->dest != target)
1790 redirect_edge_succ (e, target);
1794 /* Return last loop_beg note appearing after INSN, before start of next
1795 basic block. Return INSN if there are no such notes.
1797 When emmiting jump to redirect an fallthru edge, it should always
1798 appear after the LOOP_BEG notes, as loop optimizer expect loop to
1799 eighter start by fallthru edge or jump following the LOOP_BEG note
1800 jumping to the loop exit test.
1803 last_loop_beg_note (insn)
1807 insn = NEXT_INSN (insn);
1808 while (GET_CODE (insn) == NOTE
1809 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK)
1811 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1813 insn = NEXT_INSN (insn);
1818 /* Attempt to change code to redirect edge E to TARGET.
1819 Don't do that on expense of adding new instructions or reordering
1822 Function can be also called with edge destionation equivalent to the
1823 TARGET. Then it should try the simplifications and do nothing if
1826 Return true if transformation suceeded. We still return flase in case
1827 E already destinated TARGET and we didn't managed to simplify instruction
1830 redirect_edge_and_branch (e, target)
1835 rtx old_label = e->dest->head;
1836 basic_block src = e->src;
1837 rtx insn = src->end;
1839 if (e->flags & EDGE_COMPLEX)
1842 if (try_redirect_by_replacing_jump (e, target))
1844 /* Do this fast path late, as we want above code to simplify for cases
1845 where called on single edge leaving basic block containing nontrivial
1847 else if (e->dest == target)
1850 /* We can only redirect non-fallthru edges of jump insn. */
1851 if (e->flags & EDGE_FALLTHRU)
1853 if (GET_CODE (insn) != JUMP_INSN)
1856 /* Recognize a tablejump and adjust all matching cases. */
1857 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1858 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1859 && GET_CODE (tmp) == JUMP_INSN
1860 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1861 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1865 rtx new_label = block_label (target);
1867 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1868 vec = XVEC (PATTERN (tmp), 0);
1870 vec = XVEC (PATTERN (tmp), 1);
1872 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1873 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1875 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
1876 --LABEL_NUSES (old_label);
1877 ++LABEL_NUSES (new_label);
1880 /* Handle casesi dispatch insns */
1881 if ((tmp = single_set (insn)) != NULL
1882 && SET_DEST (tmp) == pc_rtx
1883 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1884 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1885 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1887 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1889 --LABEL_NUSES (old_label);
1890 ++LABEL_NUSES (new_label);
1895 /* ?? We may play the games with moving the named labels from
1896 one basic block to the other in case only one computed_jump is
1898 if (computed_jump_p (insn))
1901 /* A return instruction can't be redirected. */
1902 if (returnjump_p (insn))
1905 /* If the insn doesn't go where we think, we're confused. */
1906 if (JUMP_LABEL (insn) != old_label)
1908 redirect_jump (insn, block_label (target), 0);
1912 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
1913 e->src->index, e->dest->index, target->index);
1914 if (e->dest != target)
1915 redirect_edge_succ_nodup (e, target);
1919 /* Redirect edge even at the expense of creating new jump insn or
1920 basic block. Return new basic block if created, NULL otherwise.
1921 Abort if converison is impossible. */
1923 redirect_edge_and_branch_force (e, target)
1933 if (redirect_edge_and_branch (e, target))
1935 if (e->dest == target)
1937 if (e->flags & EDGE_ABNORMAL)
1939 if (!(e->flags & EDGE_FALLTHRU))
1942 e->flags &= ~EDGE_FALLTHRU;
1943 label = block_label (target);
1944 /* Case of the fallthru block. */
1945 if (!e->src->succ->succ_next)
1947 e->src->end = emit_jump_insn_after (gen_jump (label),
1948 last_loop_beg_note (e->src->end));
1949 JUMP_LABEL (e->src->end) = label;
1950 LABEL_NUSES (label)++;
1951 if (basic_block_for_insn)
1952 set_block_for_new_insns (e->src->end, e->src);
1953 emit_barrier_after (e->src->end);
1955 fprintf (rtl_dump_file,
1956 "Emitting jump insn %i to redirect edge %i->%i to %i\n",
1957 INSN_UID (e->src->end), e->src->index, e->dest->index,
1959 redirect_edge_succ (e, target);
1962 /* Redirecting fallthru edge of the conditional needs extra work. */
1965 fprintf (rtl_dump_file,
1966 "Emitting jump insn %i in new BB to redirect edge %i->%i to %i\n",
1967 INSN_UID (e->src->end), e->src->index, e->dest->index,
1970 /* Create the new structures. */
1971 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1972 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1975 memset (new_bb, 0, sizeof (*new_bb));
1977 new_bb->end = new_bb->head = last_loop_beg_note (e->src->end);
1978 new_bb->succ = NULL;
1979 new_bb->pred = new_edge;
1980 new_bb->count = e->count;
1981 new_bb->frequency = EDGE_FREQUENCY (e);
1982 new_bb->loop_depth = e->dest->loop_depth;
1984 new_edge->flags = EDGE_FALLTHRU;
1985 new_edge->probability = e->probability;
1986 new_edge->count = e->count;
1988 if (target->global_live_at_start)
1990 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1991 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1992 COPY_REG_SET (new_bb->global_live_at_start,
1993 target->global_live_at_start);
1994 COPY_REG_SET (new_bb->global_live_at_end, new_bb->global_live_at_start);
1998 new_edge->src = e->src;
1999 new_edge->dest = new_bb;
2000 new_edge->succ_next = e->src->succ;
2001 e->src->succ = new_edge;
2002 new_edge->pred_next = NULL;
2004 /* Redirect old edge. */
2005 redirect_edge_succ (e, target);
2006 redirect_edge_pred (e, new_bb);
2007 e->probability = REG_BR_PROB_BASE;
2009 /* Place the new block just after the block being split. */
2010 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2012 /* Some parts of the compiler expect blocks to be number in
2013 sequential order so insert the new block immediately after the
2014 block being split.. */
2015 j = new_edge->src->index;
2016 for (i = n_basic_blocks - 1; i > j + 1; --i)
2018 basic_block tmp = BASIC_BLOCK (i - 1);
2019 BASIC_BLOCK (i) = tmp;
2023 BASIC_BLOCK (i) = new_bb;
2026 /* Create the basic block note. */
2027 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, new_bb->head);
2028 NOTE_BASIC_BLOCK (bb_note) = new_bb;
2029 new_bb->head = bb_note;
2031 new_bb->end = emit_jump_insn_after (gen_jump (label), new_bb->head);
2032 JUMP_LABEL (new_bb->end) = label;
2033 LABEL_NUSES (label)++;
2034 if (basic_block_for_insn)
2035 set_block_for_new_insns (new_bb->end, new_bb);
2036 emit_barrier_after (new_bb->end);
2040 /* Helper function for split_edge. Return true in case edge BB2 to BB1
2041 is back edge of syntactic loop. */
2043 back_edge_of_syntactic_loop_p (bb1, bb2)
2044 basic_block bb1, bb2;
2048 if (bb1->index > bb2->index)
2050 if (bb1->index == bb2->index)
2052 for (insn = bb1->end; insn != bb2->head && count >= 0;
2053 insn = NEXT_INSN (insn))
2054 if (GET_CODE (insn) == NOTE)
2056 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
2058 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
2064 /* Split a (typically critical) edge. Return the new block.
2065 Abort on abnormal edges.
2067 ??? The code generally expects to be called on critical edges.
2068 The case of a block ending in an unconditional jump to a
2069 block with multiple predecessors is not handled optimally. */
2072 split_edge (edge_in)
2075 basic_block old_pred, bb, old_succ;
2080 /* Abnormal edges cannot be split. */
2081 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
2084 old_pred = edge_in->src;
2085 old_succ = edge_in->dest;
2087 /* Create the new structures. */
2088 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
2089 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
2092 memset (bb, 0, sizeof (*bb));
2094 /* ??? This info is likely going to be out of date very soon. */
2095 if (old_succ->global_live_at_start)
2097 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2098 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2099 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
2100 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
2104 bb->succ = edge_out;
2105 bb->count = edge_in->count;
2106 bb->frequency = EDGE_FREQUENCY (edge_in);
2108 edge_in->flags &= ~EDGE_CRITICAL;
2110 edge_out->pred_next = old_succ->pred;
2111 edge_out->succ_next = NULL;
2113 edge_out->dest = old_succ;
2114 edge_out->flags = EDGE_FALLTHRU;
2115 edge_out->probability = REG_BR_PROB_BASE;
2116 edge_out->count = edge_in->count;
2118 old_succ->pred = edge_out;
2120 /* Tricky case -- if there existed a fallthru into the successor
2121 (and we're not it) we must add a new unconditional jump around
2122 the new block we're actually interested in.
2124 Further, if that edge is critical, this means a second new basic
2125 block must be created to hold it. In order to simplify correct
2126 insn placement, do this before we touch the existing basic block
2127 ordering for the block we were really wanting. */
2128 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2131 for (e = edge_out->pred_next; e; e = e->pred_next)
2132 if (e->flags & EDGE_FALLTHRU)
2137 basic_block jump_block;
2140 if ((e->flags & EDGE_CRITICAL) == 0
2141 && e->src != ENTRY_BLOCK_PTR)
2143 /* Non critical -- we can simply add a jump to the end
2144 of the existing predecessor. */
2145 jump_block = e->src;
2149 /* We need a new block to hold the jump. The simplest
2150 way to do the bulk of the work here is to recursively
2152 jump_block = split_edge (e);
2153 e = jump_block->succ;
2156 /* Now add the jump insn ... */
2157 pos = emit_jump_insn_after (gen_jump (old_succ->head),
2158 last_loop_beg_note (jump_block->end));
2159 jump_block->end = pos;
2160 if (basic_block_for_insn)
2161 set_block_for_new_insns (pos, jump_block);
2162 emit_barrier_after (pos);
2164 /* ... let jump know that label is in use, ... */
2165 JUMP_LABEL (pos) = old_succ->head;
2166 ++LABEL_NUSES (old_succ->head);
2168 /* ... and clear fallthru on the outgoing edge. */
2169 e->flags &= ~EDGE_FALLTHRU;
2171 /* Continue splitting the interesting edge. */
2175 /* Place the new block just in front of the successor. */
2176 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2177 if (old_succ == EXIT_BLOCK_PTR)
2178 j = n_basic_blocks - 1;
2180 j = old_succ->index;
2181 for (i = n_basic_blocks - 1; i > j; --i)
2183 basic_block tmp = BASIC_BLOCK (i - 1);
2184 BASIC_BLOCK (i) = tmp;
2187 BASIC_BLOCK (i) = bb;
2190 /* Create the basic block note.
2192 Where we place the note can have a noticable impact on the generated
2193 code. Consider this cfg:
2203 If we need to insert an insn on the edge from block 0 to block 1,
2204 we want to ensure the instructions we insert are outside of any
2205 loop notes that physically sit between block 0 and block 1. Otherwise
2206 we confuse the loop optimizer into thinking the loop is a phony. */
2207 if (old_succ != EXIT_BLOCK_PTR
2208 && PREV_INSN (old_succ->head)
2209 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
2210 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG
2211 && !back_edge_of_syntactic_loop_p (old_succ, old_pred))
2212 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
2213 PREV_INSN (old_succ->head));
2214 else if (old_succ != EXIT_BLOCK_PTR)
2215 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
2217 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
2218 NOTE_BASIC_BLOCK (bb_note) = bb;
2219 bb->head = bb->end = bb_note;
2221 /* For non-fallthry edges, we must adjust the predecessor's
2222 jump instruction to target our new block. */
2223 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2225 if (!redirect_edge_and_branch (edge_in, bb))
2229 redirect_edge_succ (edge_in, bb);
2234 /* Queue instructions for insertion on an edge between two basic blocks.
2235 The new instructions and basic blocks (if any) will not appear in the
2236 CFG until commit_edge_insertions is called. */
2239 insert_insn_on_edge (pattern, e)
2243 /* We cannot insert instructions on an abnormal critical edge.
2244 It will be easier to find the culprit if we die now. */
2245 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
2246 == (EDGE_ABNORMAL|EDGE_CRITICAL))
2249 if (e->insns == NULL_RTX)
2252 push_to_sequence (e->insns);
2254 emit_insn (pattern);
2256 e->insns = get_insns ();
2260 /* Update the CFG for the instructions queued on edge E. */
2263 commit_one_edge_insertion (e)
2266 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
2269 /* Pull the insns off the edge now since the edge might go away. */
2271 e->insns = NULL_RTX;
2273 /* Figure out where to put these things. If the destination has
2274 one predecessor, insert there. Except for the exit block. */
2275 if (e->dest->pred->pred_next == NULL
2276 && e->dest != EXIT_BLOCK_PTR)
2280 /* Get the location correct wrt a code label, and "nice" wrt
2281 a basic block note, and before everything else. */
2283 if (GET_CODE (tmp) == CODE_LABEL)
2284 tmp = NEXT_INSN (tmp);
2285 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
2286 tmp = NEXT_INSN (tmp);
2287 if (tmp == bb->head)
2290 after = PREV_INSN (tmp);
2293 /* If the source has one successor and the edge is not abnormal,
2294 insert there. Except for the entry block. */
2295 else if ((e->flags & EDGE_ABNORMAL) == 0
2296 && e->src->succ->succ_next == NULL
2297 && e->src != ENTRY_BLOCK_PTR)
2300 /* It is possible to have a non-simple jump here. Consider a target
2301 where some forms of unconditional jumps clobber a register. This
2302 happens on the fr30 for example.
2304 We know this block has a single successor, so we can just emit
2305 the queued insns before the jump. */
2306 if (GET_CODE (bb->end) == JUMP_INSN)
2312 /* We'd better be fallthru, or we've lost track of what's what. */
2313 if ((e->flags & EDGE_FALLTHRU) == 0)
2320 /* Otherwise we must split the edge. */
2323 bb = split_edge (e);
2327 /* Now that we've found the spot, do the insertion. */
2329 /* Set the new block number for these insns, if structure is allocated. */
2330 if (basic_block_for_insn)
2333 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
2334 set_block_for_insn (i, bb);
2339 emit_insns_before (insns, before);
2340 if (before == bb->head)
2343 last = prev_nonnote_insn (before);
2347 last = emit_insns_after (insns, after);
2348 if (after == bb->end)
2352 if (returnjump_p (last))
2354 /* ??? Remove all outgoing edges from BB and add one for EXIT.
2355 This is not currently a problem because this only happens
2356 for the (single) epilogue, which already has a fallthru edge
2360 if (e->dest != EXIT_BLOCK_PTR
2361 || e->succ_next != NULL
2362 || (e->flags & EDGE_FALLTHRU) == 0)
2364 e->flags &= ~EDGE_FALLTHRU;
2366 emit_barrier_after (last);
2370 flow_delete_insn (before);
2372 else if (GET_CODE (last) == JUMP_INSN)
2374 find_sub_basic_blocks (bb);
2377 /* Update the CFG for all queued instructions. */
2380 commit_edge_insertions ()
2384 compute_bb_for_insn (get_max_uid ());
2386 #ifdef ENABLE_CHECKING
2387 verify_flow_info ();
2391 bb = ENTRY_BLOCK_PTR;
2396 for (e = bb->succ; e; e = next)
2398 next = e->succ_next;
2400 commit_one_edge_insertion (e);
2403 if (++i >= n_basic_blocks)
2405 bb = BASIC_BLOCK (i);
2409 /* Add fake edges to the function exit for any non constant calls in
2410 the bitmap of blocks specified by BLOCKS or to the whole CFG if
2411 BLOCKS is zero. Return the nuber of blocks that were split. */
2414 flow_call_edges_add (blocks)
2418 int blocks_split = 0;
2422 /* Map bb indicies into basic block pointers since split_block
2423 will renumber the basic blocks. */
2425 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2429 for (i = 0; i < n_basic_blocks; i++)
2430 bbs[bb_num++] = BASIC_BLOCK (i);
2434 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2436 bbs[bb_num++] = BASIC_BLOCK (i);
2441 /* Now add fake edges to the function exit for any non constant
2442 calls since there is no way that we can determine if they will
2445 for (i = 0; i < bb_num; i++)
2447 basic_block bb = bbs[i];
2451 for (insn = bb->end; ; insn = prev_insn)
2453 prev_insn = PREV_INSN (insn);
2454 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2458 /* Note that the following may create a new basic block
2459 and renumber the existing basic blocks. */
2460 e = split_block (bb, insn);
2464 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2466 if (insn == bb->head)
2472 verify_flow_info ();
2475 return blocks_split;
2478 /* Find unreachable blocks. An unreachable block will have NULL in
2479 block->aux, a non-NULL value indicates the block is reachable. */
2482 find_unreachable_blocks ()
2486 basic_block *tos, *worklist;
2489 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2491 /* Use basic_block->aux as a marker. Clear them all. */
2493 for (i = 0; i < n; ++i)
2494 BASIC_BLOCK (i)->aux = NULL;
2496 /* Add our starting points to the worklist. Almost always there will
2497 be only one. It isn't inconcievable that we might one day directly
2498 support Fortran alternate entry points. */
2500 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2504 /* Mark the block with a handy non-null value. */
2508 /* Iterate: find everything reachable from what we've already seen. */
2510 while (tos != worklist)
2512 basic_block b = *--tos;
2514 for (e = b->succ; e; e = e->succ_next)
2525 /* Delete all unreachable basic blocks. */
2527 delete_unreachable_blocks ()
2531 find_unreachable_blocks ();
2533 /* Delete all unreachable basic blocks. Count down so that we
2534 don't interfere with the block renumbering that happens in
2535 flow_delete_block. */
2537 for (i = n_basic_blocks - 1; i >= 0; --i)
2539 basic_block b = BASIC_BLOCK (i);
2542 /* This block was found. Tidy up the mark. */
2545 flow_delete_block (b);
2548 tidy_fallthru_edges ();
2551 /* Return true if NOTE is not one of the ones that must be kept paired,
2552 so that we may simply delete them. */
2555 can_delete_note_p (note)
2558 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2559 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2562 /* Unlink a chain of insns between START and FINISH, leaving notes
2563 that must be paired. */
2566 flow_delete_insn_chain (start, finish)
2569 /* Unchain the insns one by one. It would be quicker to delete all
2570 of these with a single unchaining, rather than one at a time, but
2571 we need to keep the NOTE's. */
2577 next = NEXT_INSN (start);
2578 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2580 else if (GET_CODE (start) == CODE_LABEL
2581 && ! can_delete_label_p (start))
2583 const char *name = LABEL_NAME (start);
2584 PUT_CODE (start, NOTE);
2585 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2586 NOTE_SOURCE_FILE (start) = name;
2589 next = flow_delete_insn (start);
2591 if (start == finish)
2597 /* Delete the insns in a (non-live) block. We physically delete every
2598 non-deleted-note insn, and update the flow graph appropriately.
2600 Return nonzero if we deleted an exception handler. */
2602 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2603 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2606 flow_delete_block (b)
2609 int deleted_handler = 0;
2612 /* If the head of this block is a CODE_LABEL, then it might be the
2613 label for an exception handler which can't be reached.
2615 We need to remove the label from the exception_handler_label list
2616 and remove the associated NOTE_INSN_EH_REGION_BEG and
2617 NOTE_INSN_EH_REGION_END notes. */
2621 never_reached_warning (insn);
2623 if (GET_CODE (insn) == CODE_LABEL)
2624 maybe_remove_eh_handler (insn);
2626 /* Include any jump table following the basic block. */
2628 if (GET_CODE (end) == JUMP_INSN
2629 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2630 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2631 && GET_CODE (tmp) == JUMP_INSN
2632 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2633 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2636 /* Include any barrier that may follow the basic block. */
2637 tmp = next_nonnote_insn (end);
2638 if (tmp && GET_CODE (tmp) == BARRIER)
2641 /* Selectively delete the entire chain. */
2642 flow_delete_insn_chain (insn, end);
2644 /* Remove the edges into and out of this block. Note that there may
2645 indeed be edges in, if we are removing an unreachable loop. */
2649 for (e = b->pred; e; e = next)
2651 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2654 next = e->pred_next;
2658 for (e = b->succ; e; e = next)
2660 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2663 next = e->succ_next;
2672 /* Remove the basic block from the array, and compact behind it. */
2675 return deleted_handler;
2678 /* Remove block B from the basic block array and compact behind it. */
2684 int i, n = n_basic_blocks;
2686 for (i = b->index; i + 1 < n; ++i)
2688 basic_block x = BASIC_BLOCK (i + 1);
2689 BASIC_BLOCK (i) = x;
2693 basic_block_info->num_elements--;
2697 /* Delete INSN by patching it out. Return the next insn. */
2700 flow_delete_insn (insn)
2703 rtx prev = PREV_INSN (insn);
2704 rtx next = NEXT_INSN (insn);
2707 PREV_INSN (insn) = NULL_RTX;
2708 NEXT_INSN (insn) = NULL_RTX;
2709 INSN_DELETED_P (insn) = 1;
2712 NEXT_INSN (prev) = next;
2714 PREV_INSN (next) = prev;
2716 set_last_insn (prev);
2718 if (GET_CODE (insn) == CODE_LABEL)
2719 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2721 /* If deleting a jump, decrement the use count of the label. Deleting
2722 the label itself should happen in the normal course of block merging. */
2723 if (GET_CODE (insn) == JUMP_INSN
2724 && JUMP_LABEL (insn)
2725 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2726 LABEL_NUSES (JUMP_LABEL (insn))--;
2728 /* Also if deleting an insn that references a label. */
2729 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2730 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2731 LABEL_NUSES (XEXP (note, 0))--;
2733 if (GET_CODE (insn) == JUMP_INSN
2734 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2735 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2737 rtx pat = PATTERN (insn);
2738 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
2739 int len = XVECLEN (pat, diff_vec_p);
2742 for (i = 0; i < len; i++)
2743 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
2749 /* True if a given label can be deleted. */
2752 can_delete_label_p (label)
2757 if (LABEL_PRESERVE_P (label))
2760 for (x = forced_labels; x; x = XEXP (x, 1))
2761 if (label == XEXP (x, 0))
2763 for (x = label_value_list; x; x = XEXP (x, 1))
2764 if (label == XEXP (x, 0))
2766 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2767 if (label == XEXP (x, 0))
2770 /* User declared labels must be preserved. */
2771 if (LABEL_NAME (label) != 0)
2778 tail_recursion_label_p (label)
2783 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2784 if (label == XEXP (x, 0))
2790 /* Blocks A and B are to be merged into a single block A. The insns
2791 are already contiguous, hence `nomove'. */
2794 merge_blocks_nomove (a, b)
2798 rtx b_head, b_end, a_end;
2799 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2802 /* If there was a CODE_LABEL beginning B, delete it. */
2805 if (GET_CODE (b_head) == CODE_LABEL)
2807 /* Detect basic blocks with nothing but a label. This can happen
2808 in particular at the end of a function. */
2809 if (b_head == b_end)
2811 del_first = del_last = b_head;
2812 b_head = NEXT_INSN (b_head);
2815 /* Delete the basic block note. */
2816 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2818 if (b_head == b_end)
2823 b_head = NEXT_INSN (b_head);
2826 /* If there was a jump out of A, delete it. */
2828 if (GET_CODE (a_end) == JUMP_INSN)
2832 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2833 if (GET_CODE (prev) != NOTE
2834 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2841 /* If this was a conditional jump, we need to also delete
2842 the insn that set cc0. */
2843 if (prev && sets_cc0_p (prev))
2846 prev = prev_nonnote_insn (prev);
2855 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2856 del_first = NEXT_INSN (a_end);
2858 /* Delete everything marked above as well as crap that might be
2859 hanging out between the two blocks. */
2860 flow_delete_insn_chain (del_first, del_last);
2862 /* Normally there should only be one successor of A and that is B, but
2863 partway though the merge of blocks for conditional_execution we'll
2864 be merging a TEST block with THEN and ELSE successors. Free the
2865 whole lot of them and hope the caller knows what they're doing. */
2867 remove_edge (a->succ);
2869 /* Adjust the edges out of B for the new owner. */
2870 for (e = b->succ; e; e = e->succ_next)
2874 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2875 b->pred = b->succ = NULL;
2877 /* Reassociate the insns of B with A. */
2880 if (basic_block_for_insn)
2882 BLOCK_FOR_INSN (b_head) = a;
2883 while (b_head != b_end)
2885 b_head = NEXT_INSN (b_head);
2886 BLOCK_FOR_INSN (b_head) = a;
2896 /* Blocks A and B are to be merged into a single block. A has no incoming
2897 fallthru edge, so it can be moved before B without adding or modifying
2898 any jumps (aside from the jump from A to B). */
2901 merge_blocks_move_predecessor_nojumps (a, b)
2904 rtx start, end, barrier;
2910 barrier = next_nonnote_insn (end);
2911 if (GET_CODE (barrier) != BARRIER)
2913 flow_delete_insn (barrier);
2915 /* Move block and loop notes out of the chain so that we do not
2916 disturb their order.
2918 ??? A better solution would be to squeeze out all the non-nested notes
2919 and adjust the block trees appropriately. Even better would be to have
2920 a tighter connection between block trees and rtl so that this is not
2922 start = squeeze_notes (start, end);
2924 /* Scramble the insn chain. */
2925 if (end != PREV_INSN (b->head))
2926 reorder_insns (start, end, PREV_INSN (b->head));
2930 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2931 a->index, b->index);
2934 /* Swap the records for the two blocks around. Although we are deleting B,
2935 A is now where B was and we want to compact the BB array from where
2937 BASIC_BLOCK (a->index) = b;
2938 BASIC_BLOCK (b->index) = a;
2940 a->index = b->index;
2943 /* Now blocks A and B are contiguous. Merge them. */
2944 merge_blocks_nomove (a, b);
2949 /* Blocks A and B are to be merged into a single block. B has no outgoing
2950 fallthru edge, so it can be moved after A without adding or modifying
2951 any jumps (aside from the jump from A to B). */
2954 merge_blocks_move_successor_nojumps (a, b)
2957 rtx start, end, barrier;
2961 barrier = NEXT_INSN (end);
2963 /* Recognize a jump table following block B. */
2965 && GET_CODE (barrier) == CODE_LABEL
2966 && NEXT_INSN (barrier)
2967 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2968 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2969 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2971 end = NEXT_INSN (barrier);
2972 barrier = NEXT_INSN (end);
2975 /* There had better have been a barrier there. Delete it. */
2976 if (barrier && GET_CODE (barrier) == BARRIER)
2977 flow_delete_insn (barrier);
2979 /* Move block and loop notes out of the chain so that we do not
2980 disturb their order.
2982 ??? A better solution would be to squeeze out all the non-nested notes
2983 and adjust the block trees appropriately. Even better would be to have
2984 a tighter connection between block trees and rtl so that this is not
2986 start = squeeze_notes (start, end);
2988 /* Scramble the insn chain. */
2989 reorder_insns (start, end, a->end);
2991 /* Now blocks A and B are contiguous. Merge them. */
2992 merge_blocks_nomove (a, b);
2996 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2997 b->index, a->index);
3003 /* Attempt to merge basic blocks that are potentially non-adjacent.
3004 Return true iff the attempt succeeded. */
3007 merge_blocks (e, b, c, mode)
3012 /* If C has a tail recursion label, do not merge. There is no
3013 edge recorded from the call_placeholder back to this label, as
3014 that would make optimize_sibling_and_tail_recursive_calls more
3015 complex for no gain. */
3016 if (GET_CODE (c->head) == CODE_LABEL
3017 && tail_recursion_label_p (c->head))
3020 /* If B has a fallthru edge to C, no need to move anything. */
3021 if (e->flags & EDGE_FALLTHRU)
3023 merge_blocks_nomove (b, c);
3027 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
3028 b->index, c->index);
3033 /* Otherwise we will need to move code around. Do that only if expensive
3034 transformations are allowed. */
3035 else if (mode & CLEANUP_EXPENSIVE)
3037 edge tmp_edge, c_fallthru_edge;
3038 int c_has_outgoing_fallthru;
3039 int b_has_incoming_fallthru;
3041 /* Avoid overactive code motion, as the forwarder blocks should be
3042 eliminated by edge redirection instead. One exception might have
3043 been if B is a forwarder block and C has no fallthru edge, but
3044 that should be cleaned up by bb-reorder instead. */
3045 if (forwarder_block_p (b) || forwarder_block_p (c))
3048 /* We must make sure to not munge nesting of lexical blocks,
3049 and loop notes. This is done by squeezing out all the notes
3050 and leaving them there to lie. Not ideal, but functional. */
3052 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
3053 if (tmp_edge->flags & EDGE_FALLTHRU)
3055 c_has_outgoing_fallthru = (tmp_edge != NULL);
3056 c_fallthru_edge = tmp_edge;
3058 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
3059 if (tmp_edge->flags & EDGE_FALLTHRU)
3061 b_has_incoming_fallthru = (tmp_edge != NULL);
3063 /* If B does not have an incoming fallthru, then it can be moved
3064 immediately before C without introducing or modifying jumps.
3065 C cannot be the first block, so we do not have to worry about
3066 accessing a non-existent block. */
3067 if (! b_has_incoming_fallthru)
3068 return merge_blocks_move_predecessor_nojumps (b, c);
3070 /* Otherwise, we're going to try to move C after B. If C does
3071 not have an outgoing fallthru, then it can be moved
3072 immediately after B without introducing or modifying jumps. */
3073 if (! c_has_outgoing_fallthru)
3074 return merge_blocks_move_successor_nojumps (b, c);
3076 /* Otherwise, we'll need to insert an extra jump, and possibly
3077 a new block to contain it. We can't redirect to EXIT_BLOCK_PTR,
3078 as we don't have explicit return instructions before epilogues
3079 are generated, so give up on that case. */
3081 if (c_fallthru_edge->dest != EXIT_BLOCK_PTR
3082 && merge_blocks_move_successor_nojumps (b, c))
3084 basic_block target = c_fallthru_edge->dest;
3088 /* This is a dirty hack to avoid code duplication.
3090 Set edge to point to wrong basic block, so
3091 redirect_edge_and_branch_force will do the trick
3092 and rewire edge back to the original location. */
3093 redirect_edge_succ (c_fallthru_edge, ENTRY_BLOCK_PTR);
3094 new = redirect_edge_and_branch_force (c_fallthru_edge, target);
3096 /* We've just created barrier, but another barrier is
3097 already present in the stream. Avoid the duplicate. */
3098 barrier = next_nonnote_insn (new ? new->end : b->end);
3099 if (GET_CODE (barrier) != BARRIER)
3101 flow_delete_insn (barrier);
3109 /* Simplify a conditional jump around an unconditional jump.
3110 Return true if something changed. */
3113 try_simplify_condjump (cbranch_block)
3114 basic_block cbranch_block;
3116 basic_block jump_block, jump_dest_block, cbranch_dest_block;
3117 edge cbranch_jump_edge, cbranch_fallthru_edge;
3120 /* Verify that there are exactly two successors. */
3121 if (!cbranch_block->succ
3122 || !cbranch_block->succ->succ_next
3123 || cbranch_block->succ->succ_next->succ_next)
3126 /* Verify that we've got a normal conditional branch at the end
3128 cbranch_insn = cbranch_block->end;
3129 if (!any_condjump_p (cbranch_insn))
3132 cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block);
3133 cbranch_jump_edge = BRANCH_EDGE (cbranch_block);
3135 /* The next block must not have multiple predecessors, must not
3136 be the last block in the function, and must contain just the
3137 unconditional jump. */
3138 jump_block = cbranch_fallthru_edge->dest;
3139 if (jump_block->pred->pred_next
3140 || jump_block->index == n_basic_blocks - 1
3141 || !forwarder_block_p (jump_block))
3143 jump_dest_block = jump_block->succ->dest;
3145 /* The conditional branch must target the block after the
3146 unconditional branch. */
3147 cbranch_dest_block = cbranch_jump_edge->dest;
3149 if (!can_fallthru (jump_block, cbranch_dest_block))
3152 /* Invert the conditional branch. Prevent jump.c from deleting
3153 "unreachable" instructions. */
3154 LABEL_NUSES (JUMP_LABEL (cbranch_insn))++;
3155 if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 1))
3157 LABEL_NUSES (JUMP_LABEL (cbranch_insn))--;
3162 fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n",
3163 INSN_UID (cbranch_insn), INSN_UID (jump_block->end));
3165 /* Success. Update the CFG to match. Note that after this point
3166 the edge variable names appear backwards; the redirection is done
3167 this way to preserve edge profile data. */
3168 redirect_edge_succ_nodup (cbranch_jump_edge, cbranch_dest_block);
3169 redirect_edge_succ_nodup (cbranch_fallthru_edge, jump_dest_block);
3170 cbranch_jump_edge->flags |= EDGE_FALLTHRU;
3171 cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
3173 /* Delete the block with the unconditional jump, and clean up the mess. */
3174 flow_delete_block (jump_block);
3175 tidy_fallthru_edge (cbranch_jump_edge, cbranch_block, cbranch_dest_block);
3180 /* Attempt to forward edges leaving basic block B.
3181 Return true if sucessful. */
3184 try_forward_edges (b)
3187 bool changed = false;
3190 for (e = b->succ; e ; e = next)
3192 basic_block target, first;
3195 next = e->succ_next;
3197 /* Skip complex edges because we don't know how to update them.
3199 Still handle fallthru edges, as we can suceed to forward fallthru
3200 edge to the same place as the branch edge of conditional branch
3201 and turn conditional branch to an unconditonal branch. */
3202 if (e->flags & EDGE_COMPLEX)
3205 target = first = e->dest;
3208 /* Look for the real destination of the jump.
3209 Avoid inifinite loop in the infinite empty loop by counting
3210 up to n_basic_blocks. */
3211 while (forwarder_block_p (target)
3212 && target->succ->dest != EXIT_BLOCK_PTR
3213 && counter < n_basic_blocks)
3215 /* Bypass trivial infinite loops. */
3216 if (target == target->succ->dest)
3217 counter = n_basic_blocks;
3218 target = target->succ->dest, counter++;
3221 if (counter >= n_basic_blocks)
3224 fprintf (rtl_dump_file, "Infinite loop in BB %i.\n",
3227 else if (target == first)
3228 ; /* We didn't do anything. */
3231 /* Save the values now, as the edge may get removed. */
3232 gcov_type edge_count = e->count;
3233 int edge_probability = e->probability;
3235 if (redirect_edge_and_branch (e, target))
3237 /* We successfully forwarded the edge. Now update profile
3238 data: for each edge we traversed in the chain, remove
3239 the original edge's execution count. */
3240 int edge_frequency = ((edge_probability * b->frequency
3241 + REG_BR_PROB_BASE / 2)
3242 / REG_BR_PROB_BASE);
3246 first->count -= edge_count;
3247 first->succ->count -= edge_count;
3248 first->frequency -= edge_frequency;
3249 first = first->succ->dest;
3251 while (first != target);
3258 fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n",
3259 b->index, e->dest->index, target->index);
3267 /* Look through the insns at the end of BB1 and BB2 and find the longest
3268 sequence that are equivalent. Store the first insns for that sequence
3269 in *F1 and *F2 and return the sequence length.
3271 To simplify callers of this function, if the blocks match exactly,
3272 store the head of the blocks in *F1 and *F2. */
3275 flow_find_cross_jump (mode, bb1, bb2, f1, f2)
3276 int mode ATTRIBUTE_UNUSED;
3277 basic_block bb1, bb2;
3280 rtx i1, i2, p1, p2, last1, last2, afterlast1, afterlast2;
3283 /* Skip simple jumps at the end of the blocks. Complex jumps still
3284 need to be compared for equivalence, which we'll do below. */
3287 if (onlyjump_p (i1))
3288 i1 = PREV_INSN (i1);
3290 if (onlyjump_p (i2))
3291 i2 = PREV_INSN (i2);
3293 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
3297 while ((GET_CODE (i1) == NOTE && i1 != bb1->head))
3298 i1 = PREV_INSN (i1);
3299 while ((GET_CODE (i2) == NOTE && i2 != bb2->head))
3300 i2 = PREV_INSN (i2);
3302 if (i1 == bb1->head || i2 == bb2->head)
3305 /* Verify that I1 and I2 are equivalent. */
3307 if (GET_CODE (i1) != GET_CODE (i2))
3313 /* If this is a CALL_INSN, compare register usage information.
3314 If we don't check this on stack register machines, the two
3315 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3316 numbers of stack registers in the same basic block.
3317 If we don't check this on machines with delay slots, a delay slot may
3318 be filled that clobbers a parameter expected by the subroutine.
3320 ??? We take the simple route for now and assume that if they're
3321 equal, they were constructed identically. */
3323 if (GET_CODE (i1) == CALL_INSN
3324 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3325 CALL_INSN_FUNCTION_USAGE (i2)))
3329 /* If cross_jump_death_matters is not 0, the insn's mode
3330 indicates whether or not the insn contains any stack-like
3333 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
3335 /* If register stack conversion has already been done, then
3336 death notes must also be compared before it is certain that
3337 the two instruction streams match. */
3340 HARD_REG_SET i1_regset, i2_regset;
3342 CLEAR_HARD_REG_SET (i1_regset);
3343 CLEAR_HARD_REG_SET (i2_regset);
3345 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3346 if (REG_NOTE_KIND (note) == REG_DEAD
3347 && STACK_REG_P (XEXP (note, 0)))
3348 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3350 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3351 if (REG_NOTE_KIND (note) == REG_DEAD
3352 && STACK_REG_P (XEXP (note, 0)))
3353 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3355 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3364 if (GET_CODE (p1) != GET_CODE (p2))
3367 if (! rtx_renumbered_equal_p (p1, p2))
3369 /* The following code helps take care of G++ cleanups. */
3370 rtx equiv1 = find_reg_equal_equiv_note (i1);
3371 rtx equiv2 = find_reg_equal_equiv_note (i2);
3373 if (equiv1 && equiv2
3374 /* If the equivalences are not to a constant, they may
3375 reference pseudos that no longer exist, so we can't
3377 && CONSTANT_P (XEXP (equiv1, 0))
3378 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3380 rtx s1 = single_set (i1);
3381 rtx s2 = single_set (i2);
3382 if (s1 != 0 && s2 != 0
3383 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3385 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3386 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3387 if (! rtx_renumbered_equal_p (p1, p2))
3389 else if (apply_change_group ())
3397 /* Don't begin a cross-jump with a USE or CLOBBER insn. */
3398 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3400 afterlast1 = last1, afterlast2 = last2;
3401 last1 = i1, last2 = i2;
3404 i1 = PREV_INSN (i1);
3405 i2 = PREV_INSN (i2);
3411 /* Don't allow the insn after a compare to be shared by
3412 cross-jumping unless the compare is also shared. */
3413 if (reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1))
3414 last1 = afterlast1, last2 = afterlast2, ninsns--;
3418 /* Include preceeding notes and labels in the cross-jump. One,
3419 this may bring us to the head of the blocks as requested above.
3420 Two, it keeps line number notes as matched as may be. */
3423 while (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == NOTE)
3424 last1 = PREV_INSN (last1);
3425 if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL)
3426 last1 = PREV_INSN (last1);
3427 while (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == NOTE)
3428 last2 = PREV_INSN (last2);
3429 if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL)
3430 last2 = PREV_INSN (last2);
3439 /* Return true iff outgoing edges of BB1 and BB2 match, together with
3440 the branch instruction. This means that if we commonize the control
3441 flow before end of the basic block, the semantic remains unchanged.
3443 We may assume that there exists one edge with a common destination. */
3446 outgoing_edges_match (bb1, bb2)
3450 /* If BB1 has only one successor, we must be looking at an unconditional
3451 jump. Which, by the assumption above, means that we only need to check
3452 that BB2 has one successor. */
3453 if (bb1->succ && !bb1->succ->succ_next)
3454 return (bb2->succ && !bb2->succ->succ_next);
3456 /* Match conditional jumps - this may get tricky when fallthru and branch
3457 edges are crossed. */
3459 && bb1->succ->succ_next
3460 && !bb1->succ->succ_next->succ_next
3461 && any_condjump_p (bb1->end))
3463 edge b1, f1, b2, f2;
3464 bool reverse, match;
3465 rtx set1, set2, cond1, cond2;
3466 enum rtx_code code1, code2;
3469 || !bb2->succ->succ_next
3470 || bb1->succ->succ_next->succ_next
3471 || !any_condjump_p (bb2->end))
3474 b1 = BRANCH_EDGE (bb1);
3475 b2 = BRANCH_EDGE (bb2);
3476 f1 = FALLTHRU_EDGE (bb1);
3477 f2 = FALLTHRU_EDGE (bb2);
3479 /* Get around possible forwarders on fallthru edges. Other cases
3480 should be optimized out already. */
3481 if (forwarder_block_p (f1->dest))
3482 f1 = f1->dest->succ;
3483 if (forwarder_block_p (f2->dest))
3484 f2 = f2->dest->succ;
3486 /* To simplify use of this function, return false if there are
3487 unneeded forwarder blocks. These will get eliminated later
3488 during cleanup_cfg. */
3489 if (forwarder_block_p (f1->dest)
3490 || forwarder_block_p (f2->dest)
3491 || forwarder_block_p (b1->dest)
3492 || forwarder_block_p (b2->dest))
3495 if (f1->dest == f2->dest && b1->dest == b2->dest)
3497 else if (f1->dest == b2->dest && b1->dest == f2->dest)
3502 set1 = pc_set (bb1->end);
3503 set2 = pc_set (bb2->end);
3504 if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
3505 != (XEXP (SET_SRC (set2), 1) == pc_rtx))
3508 cond1 = XEXP (SET_SRC (set1), 0);
3509 cond2 = XEXP (SET_SRC (set2), 0);
3510 code1 = GET_CODE (cond1);
3512 code2 = reversed_comparison_code (cond2, bb2->end);
3514 code2 = GET_CODE (cond2);
3515 if (code2 == UNKNOWN)
3518 /* Verify codes and operands match. */
3519 match = ((code1 == code2
3520 && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
3521 && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
3522 || (code1 == swap_condition (code2)
3523 && rtx_renumbered_equal_p (XEXP (cond1, 1),
3525 && rtx_renumbered_equal_p (XEXP (cond1, 0),
3528 /* If we return true, we will join the blocks. Which means that
3529 we will only have one branch prediction bit to work with. Thus
3530 we require the existing branches to have probabilities that are
3532 /* ??? We should use bb->frequency to allow merging in infrequently
3533 executed blocks, but at the moment it is not available when
3534 cleanup_cfg is run. */
3535 if (match && !optimize_size)
3539 note1 = find_reg_note (bb1->end, REG_BR_PROB, 0);
3540 note2 = find_reg_note (bb2->end, REG_BR_PROB, 0);
3544 prob1 = INTVAL (XEXP (note1, 0));
3545 prob2 = INTVAL (XEXP (note2, 0));
3547 prob2 = REG_BR_PROB_BASE - prob2;
3549 /* Fail if the difference in probabilities is
3551 if (abs (prob1 - prob2) > REG_BR_PROB_BASE / 20)
3554 else if (note1 || note2)
3558 if (rtl_dump_file && match)
3559 fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n",
3560 bb1->index, bb2->index);
3565 /* ??? We can handle computed jumps too. This may be important for
3566 inlined functions containing switch statements. Also jumps w/o
3567 fallthru edges can be handled by simply matching whole insn. */
3571 /* E1 and E2 are edges with the same destination block. Search their
3572 predecessors for common code. If found, redirect control flow from
3573 (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */
3576 try_crossjump_to_edge (mode, e1, e2)
3581 basic_block src1 = e1->src, src2 = e2->src;
3582 basic_block redirect_to;
3583 rtx newpos1, newpos2;
3589 /* Search backward through forwarder blocks. We don't need to worry
3590 about multiple entry or chained forwarders, as they will be optimized
3591 away. We do this to look past the unconditional jump following a
3592 conditional jump that is required due to the current CFG shape. */
3594 && !src1->pred->pred_next
3595 && forwarder_block_p (src1))
3601 && !src2->pred->pred_next
3602 && forwarder_block_p (src2))
3608 /* Nothing to do if we reach ENTRY, or a common source block. */
3609 if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR)
3614 /* Seeing more than 1 forwarder blocks would confuse us later... */
3615 if (forwarder_block_p (e1->dest)
3616 && forwarder_block_p (e1->dest->succ->dest))
3618 if (forwarder_block_p (e2->dest)
3619 && forwarder_block_p (e2->dest->succ->dest))
3622 /* Likewise with dead code (possibly newly created by the other optimizations
3624 if (!src1->pred || !src2->pred)
3627 /* Likewise with complex edges.
3628 ??? We should be able to handle most complex edges later with some
3630 if (e1->flags & EDGE_COMPLEX)
3633 /* Look for the common insn sequence, part the first ... */
3634 if (!outgoing_edges_match (src1, src2))
3637 /* ... and part the second. */
3638 nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2);
3642 /* Avoid splitting if possible. */
3643 if (newpos2 == src2->head)
3648 fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n",
3649 src2->index, nmatch);
3650 redirect_to = split_block (src2, PREV_INSN (newpos2))->dest;
3654 fprintf (rtl_dump_file,
3655 "Cross jumping from bb %i to bb %i; %i common insns\n",
3656 src1->index, src2->index, nmatch);
3658 redirect_to->count += src1->count;
3659 redirect_to->frequency += src1->frequency;
3661 /* Recompute the frequencies and counts of outgoing edges. */
3662 for (s = redirect_to->succ; s; s = s->succ_next)
3665 basic_block d = s->dest;
3667 if (forwarder_block_p (d))
3669 for (s2 = src1->succ; ; s2 = s2->succ_next)
3671 basic_block d2 = s2->dest;
3672 if (forwarder_block_p (d2))
3673 d2 = d2->succ->dest;
3677 s->count += s2->count;
3679 /* Take care to update possible forwarder blocks. We verified
3680 that there is no more than one in the chain, so we can't run
3681 into infinite loop. */
3682 if (forwarder_block_p (s->dest))
3684 s->dest->succ->count += s2->count;
3685 s->dest->count += s2->count;
3686 s->dest->frequency += EDGE_FREQUENCY (s);
3688 if (forwarder_block_p (s2->dest))
3690 s2->dest->succ->count -= s2->count;
3691 s2->dest->count -= s2->count;
3692 s2->dest->frequency -= EDGE_FREQUENCY (s);
3694 if (!redirect_to->frequency && !src1->frequency)
3695 s->probability = (s->probability + s2->probability) / 2;
3698 ((s->probability * redirect_to->frequency +
3699 s2->probability * src1->frequency)
3700 / (redirect_to->frequency + src1->frequency));
3703 note = find_reg_note (redirect_to->end, REG_BR_PROB, 0);
3705 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (redirect_to)->probability);
3707 /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */
3709 /* Skip possible basic block header. */
3710 if (GET_CODE (newpos1) == CODE_LABEL)
3711 newpos1 = NEXT_INSN (newpos1);
3712 if (GET_CODE (newpos1) == NOTE)
3713 newpos1 = NEXT_INSN (newpos1);
3716 /* Emit the jump insn. */
3717 label = block_label (redirect_to);
3718 src1->end = emit_jump_insn_before (gen_jump (label), newpos1);
3719 JUMP_LABEL (src1->end) = label;
3720 LABEL_NUSES (label)++;
3721 if (basic_block_for_insn)
3722 set_block_for_new_insns (src1->end, src1);
3724 /* Delete the now unreachable instructions. */
3725 flow_delete_insn_chain (newpos1, last);
3727 /* Make sure there is a barrier after the new jump. */
3728 last = next_nonnote_insn (src1->end);
3729 if (!last || GET_CODE (last) != BARRIER)
3730 emit_barrier_after (src1->end);
3734 remove_edge (src1->succ);
3735 make_edge (NULL, src1, redirect_to, 0);
3736 src1->succ->probability = REG_BR_PROB_BASE;
3737 src1->succ->count = src1->count;
3742 /* Search the predecessors of BB for common insn sequences. When found,
3743 share code between them by redirecting control flow. Return true if
3744 any changes made. */
3747 try_crossjump_bb (mode, bb)
3751 edge e, e2, nexte2, nexte, fallthru;
3754 /* Nothing to do if there is not at least two incomming edges. */
3755 if (!bb->pred || !bb->pred->pred_next)
3758 /* It is always cheapest to redirect a block that ends in a branch to
3759 a block that falls through into BB, as that adds no branches to the
3760 program. We'll try that combination first. */
3761 for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next)
3762 if (fallthru->flags & EDGE_FALLTHRU)
3766 for (e = bb->pred; e; e = nexte)
3768 nexte = e->pred_next;
3770 /* Elide complex edges now, as neither try_crossjump_to_edge
3771 nor outgoing_edges_match can handle them. */
3772 if (e->flags & EDGE_COMPLEX)
3775 /* As noted above, first try with the fallthru predecessor. */
3778 /* Don't combine the fallthru edge into anything else.
3779 If there is a match, we'll do it the other way around. */
3783 if (try_crossjump_to_edge (mode, e, fallthru))
3791 /* Non-obvious work limiting check: Recognize that we're going
3792 to call try_crossjump_bb on every basic block. So if we have
3793 two blocks with lots of outgoing edges (a switch) and they
3794 share lots of common destinations, then we would do the
3795 cross-jump check once for each common destination.
3797 Now, if the blocks actually are cross-jump candidates, then
3798 all of their destinations will be shared. Which means that
3799 we only need check them for cross-jump candidacy once. We
3800 can eliminate redundant checks of crossjump(A,B) by arbitrarily
3801 choosing to do the check from the block for which the edge
3802 in question is the first successor of A. */
3803 if (e->src->succ != e)
3806 for (e2 = bb->pred; e2; e2 = nexte2)
3808 nexte2 = e2->pred_next;
3813 /* We've already checked the fallthru edge above. */
3817 /* Again, neither try_crossjump_to_edge nor outgoing_edges_match
3818 can handle complex edges. */
3819 if (e2->flags & EDGE_COMPLEX)
3822 /* The "first successor" check above only prevents multiple
3823 checks of crossjump(A,B). In order to prevent redundant
3824 checks of crossjump(B,A), require that A be the block
3825 with the lowest index. */
3826 if (e->src->index > e2->src->index)
3829 if (try_crossjump_to_edge (mode, e, e2))
3841 /* Do simple CFG optimizations - basic block merging, simplifying of jump
3842 instructions etc. Return nonzero if changes were made. */
3845 try_optimize_cfg (mode)
3849 bool changed_overall = false;
3853 /* Attempt to merge blocks as made possible by edge removal. If a block
3854 has only one successor, and the successor has only one predecessor,
3855 they may be combined. */
3863 fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n",
3866 for (i = 0; i < n_basic_blocks;)
3868 basic_block c, b = BASIC_BLOCK (i);
3870 bool changed_here = false;
3872 /* Delete trivially dead basic blocks. */
3873 while (b->pred == NULL)
3875 c = BASIC_BLOCK (b->index - 1);
3877 fprintf (rtl_dump_file, "Deleting block %i.\n", b->index);
3878 flow_delete_block (b);
3883 /* Remove code labels no longer used. Don't do this before
3884 CALL_PLACEHOLDER is removed, as some branches may be hidden
3886 if (b->pred->pred_next == NULL
3887 && (b->pred->flags & EDGE_FALLTHRU)
3888 && !(b->pred->flags & EDGE_COMPLEX)
3889 && GET_CODE (b->head) == CODE_LABEL
3890 && (!(mode & CLEANUP_PRE_SIBCALL)
3891 || !tail_recursion_label_p (b->head))
3892 /* If previous block ends with condjump jumping to next BB,
3893 we can't delete the label. */
3894 && (b->pred->src == ENTRY_BLOCK_PTR
3895 || !reg_mentioned_p (b->head, b->pred->src->end)))
3897 rtx label = b->head;
3898 b->head = NEXT_INSN (b->head);
3899 flow_delete_insn_chain (label, label);
3901 fprintf (rtl_dump_file, "Deleted label in block %i.\n",
3905 /* If we fall through an empty block, we can remove it. */
3906 if (b->pred->pred_next == NULL
3907 && (b->pred->flags & EDGE_FALLTHRU)
3908 && GET_CODE (b->head) != CODE_LABEL
3909 && forwarder_block_p (b)
3910 /* Note that forwarder_block_p true ensures that there
3911 is a successor for this block. */
3912 && (b->succ->flags & EDGE_FALLTHRU)
3913 && n_basic_blocks > 1)
3916 fprintf (rtl_dump_file, "Deleting fallthru block %i.\n",
3918 c = BASIC_BLOCK (b->index ? b->index - 1 : 1);
3919 redirect_edge_succ_nodup (b->pred, b->succ->dest);
3920 flow_delete_block (b);
3925 /* Merge blocks. Loop because chains of blocks might be
3927 while ((s = b->succ) != NULL
3928 && s->succ_next == NULL
3929 && !(s->flags & EDGE_COMPLEX)
3930 && (c = s->dest) != EXIT_BLOCK_PTR
3931 && c->pred->pred_next == NULL
3932 /* If the jump insn has side effects,
3933 we can't kill the edge. */
3934 && (GET_CODE (b->end) != JUMP_INSN
3935 || onlyjump_p (b->end))
3936 && merge_blocks (s, b, c, mode))
3937 changed_here = true;
3939 /* Simplify branch over branch. */
3940 if ((mode & CLEANUP_EXPENSIVE) && try_simplify_condjump (b))
3941 changed_here = true;
3943 /* If B has a single outgoing edge, but uses a non-trivial jump
3944 instruction without side-effects, we can either delete the
3945 jump entirely, or replace it with a simple unconditional jump.
3946 Use redirect_edge_and_branch to do the dirty work. */
3948 && ! b->succ->succ_next
3949 && b->succ->dest != EXIT_BLOCK_PTR
3950 && onlyjump_p (b->end)
3951 && redirect_edge_and_branch (b->succ, b->succ->dest))
3952 changed_here = true;
3954 /* Simplify branch to branch. */
3955 if (try_forward_edges (b))
3956 changed_here = true;
3958 /* Look for shared code between blocks. */
3959 if ((mode & CLEANUP_CROSSJUMP)
3960 && try_crossjump_bb (mode, b))
3961 changed_here = true;
3963 /* Don't get confused by the index shift caused by deleting
3971 if ((mode & CLEANUP_CROSSJUMP)
3972 && try_crossjump_bb (mode, EXIT_BLOCK_PTR))
3975 #ifdef ENABLE_CHECKING
3977 verify_flow_info ();
3980 changed_overall |= changed;
3983 return changed_overall;
3986 /* The given edge should potentially be a fallthru edge. If that is in
3987 fact true, delete the jump and barriers that are in the way. */
3990 tidy_fallthru_edge (e, b, c)
3996 /* ??? In a late-running flow pass, other folks may have deleted basic
3997 blocks by nopping out blocks, leaving multiple BARRIERs between here
3998 and the target label. They ought to be chastized and fixed.
4000 We can also wind up with a sequence of undeletable labels between
4001 one block and the next.
4003 So search through a sequence of barriers, labels, and notes for
4004 the head of block C and assert that we really do fall through. */
4006 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
4009 /* Remove what will soon cease being the jump insn from the source block.
4010 If block B consisted only of this single jump, turn it into a deleted
4013 if (GET_CODE (q) == JUMP_INSN
4015 && (any_uncondjump_p (q)
4016 || (b->succ == e && e->succ_next == NULL)))
4019 /* If this was a conditional jump, we need to also delete
4020 the insn that set cc0. */
4021 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
4028 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
4029 NOTE_SOURCE_FILE (q) = 0;
4035 /* We don't want a block to end on a line-number note since that has
4036 the potential of changing the code between -g and not -g. */
4037 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
4044 /* Selectively unlink the sequence. */
4045 if (q != PREV_INSN (c->head))
4046 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
4048 e->flags |= EDGE_FALLTHRU;
4051 /* Fix up edges that now fall through, or rather should now fall through
4052 but previously required a jump around now deleted blocks. Simplify
4053 the search by only examining blocks numerically adjacent, since this
4054 is how find_basic_blocks created them. */
4057 tidy_fallthru_edges ()
4061 for (i = 1; i < n_basic_blocks; ++i)
4063 basic_block b = BASIC_BLOCK (i - 1);
4064 basic_block c = BASIC_BLOCK (i);
4067 /* We care about simple conditional or unconditional jumps with
4070 If we had a conditional branch to the next instruction when
4071 find_basic_blocks was called, then there will only be one
4072 out edge for the block which ended with the conditional
4073 branch (since we do not create duplicate edges).
4075 Furthermore, the edge will be marked as a fallthru because we
4076 merge the flags for the duplicate edges. So we do not want to
4077 check that the edge is not a FALLTHRU edge. */
4078 if ((s = b->succ) != NULL
4079 && ! (s->flags & EDGE_COMPLEX)
4080 && s->succ_next == NULL
4082 /* If the jump insn has side effects, we can't tidy the edge. */
4083 && (GET_CODE (b->end) != JUMP_INSN
4084 || onlyjump_p (b->end)))
4085 tidy_fallthru_edge (s, b, c);
4089 /* Perform data flow analysis.
4090 F is the first insn of the function; FLAGS is a set of PROP_* flags
4091 to be used in accumulating flow info. */
4094 life_analysis (f, file, flags)
4099 #ifdef ELIMINABLE_REGS
4101 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
4104 /* Record which registers will be eliminated. We use this in
4107 CLEAR_HARD_REG_SET (elim_reg_set);
4109 #ifdef ELIMINABLE_REGS
4110 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
4111 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
4113 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
4117 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
4119 /* The post-reload life analysis have (on a global basis) the same
4120 registers live as was computed by reload itself. elimination
4121 Otherwise offsets and such may be incorrect.
4123 Reload will make some registers as live even though they do not
4126 We don't want to create new auto-incs after reload, since they
4127 are unlikely to be useful and can cause problems with shared
4129 if (reload_completed)
4130 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
4132 /* We want alias analysis information for local dead store elimination. */
4133 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4134 init_alias_analysis ();
4136 /* Always remove no-op moves. Do this before other processing so
4137 that we don't have to keep re-scanning them. */
4138 delete_noop_moves (f);
4140 /* Some targets can emit simpler epilogues if they know that sp was
4141 not ever modified during the function. After reload, of course,
4142 we've already emitted the epilogue so there's no sense searching. */
4143 if (! reload_completed)
4144 notice_stack_pointer_modification (f);
4146 /* Allocate and zero out data structures that will record the
4147 data from lifetime analysis. */
4148 allocate_reg_life_data ();
4149 allocate_bb_life_data ();
4151 /* Find the set of registers live on function exit. */
4152 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
4154 /* "Update" life info from zero. It'd be nice to begin the
4155 relaxation with just the exit and noreturn blocks, but that set
4156 is not immediately handy. */
4158 if (flags & PROP_REG_INFO)
4159 memset (regs_ever_live, 0, sizeof (regs_ever_live));
4160 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
4163 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4164 end_alias_analysis ();
4167 dump_flow_info (file);
4169 free_basic_block_vars (1);
4171 #ifdef ENABLE_CHECKING
4175 /* Search for any REG_LABEL notes which reference deleted labels. */
4176 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4178 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4180 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
4185 /* Removing dead insns should've made jumptables really dead. */
4186 delete_dead_jumptables ();
4189 /* A subroutine of verify_wide_reg, called through for_each_rtx.
4190 Search for REGNO. If found, abort if it is not wider than word_mode. */
4193 verify_wide_reg_1 (px, pregno)
4198 unsigned int regno = *(int *) pregno;
4200 if (GET_CODE (x) == REG && REGNO (x) == regno)
4202 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
4209 /* A subroutine of verify_local_live_at_start. Search through insns
4210 between HEAD and END looking for register REGNO. */
4213 verify_wide_reg (regno, head, end)
4220 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
4224 head = NEXT_INSN (head);
4227 /* We didn't find the register at all. Something's way screwy. */
4229 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
4230 print_rtl_and_abort ();
4233 /* A subroutine of update_life_info. Verify that there are no untoward
4234 changes in live_at_start during a local update. */
4237 verify_local_live_at_start (new_live_at_start, bb)
4238 regset new_live_at_start;
4241 if (reload_completed)
4243 /* After reload, there are no pseudos, nor subregs of multi-word
4244 registers. The regsets should exactly match. */
4245 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
4249 fprintf (rtl_dump_file,
4250 "live_at_start mismatch in bb %d, aborting\n",
4252 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
4253 debug_bitmap_file (rtl_dump_file, new_live_at_start);
4255 print_rtl_and_abort ();
4262 /* Find the set of changed registers. */
4263 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
4265 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
4267 /* No registers should die. */
4268 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
4271 fprintf (rtl_dump_file,
4272 "Register %d died unexpectedly in block %d\n", i,
4274 print_rtl_and_abort ();
4277 /* Verify that the now-live register is wider than word_mode. */
4278 verify_wide_reg (i, bb->head, bb->end);
4283 /* Updates life information starting with the basic blocks set in BLOCKS.
4284 If BLOCKS is null, consider it to be the universal set.
4286 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
4287 we are only expecting local modifications to basic blocks. If we find
4288 extra registers live at the beginning of a block, then we either killed
4289 useful data, or we have a broken split that wants data not provided.
4290 If we find registers removed from live_at_start, that means we have
4291 a broken peephole that is killing a register it shouldn't.
4293 ??? This is not true in one situation -- when a pre-reload splitter
4294 generates subregs of a multi-word pseudo, current life analysis will
4295 lose the kill. So we _can_ have a pseudo go live. How irritating.
4297 Including PROP_REG_INFO does not properly refresh regs_ever_live
4298 unless the caller resets it to zero. */
4301 update_life_info (blocks, extent, prop_flags)
4303 enum update_life_extent extent;
4307 regset_head tmp_head;
4310 tmp = INITIALIZE_REG_SET (tmp_head);
4312 /* Changes to the CFG are only allowed when
4313 doing a global update for the entire CFG. */
4314 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
4315 && (extent == UPDATE_LIFE_LOCAL || blocks))
4318 /* For a global update, we go through the relaxation process again. */
4319 if (extent != UPDATE_LIFE_LOCAL)
4325 calculate_global_regs_live (blocks, blocks,
4326 prop_flags & (PROP_SCAN_DEAD_CODE
4327 | PROP_ALLOW_CFG_CHANGES));
4329 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
4330 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
4333 /* Removing dead code may allow the CFG to be simplified which
4334 in turn may allow for further dead code detection / removal. */
4335 for (i = n_basic_blocks - 1; i >= 0; --i)
4337 basic_block bb = BASIC_BLOCK (i);
4339 COPY_REG_SET (tmp, bb->global_live_at_end);
4340 changed |= propagate_block (bb, tmp, NULL, NULL,
4341 prop_flags & (PROP_SCAN_DEAD_CODE
4342 | PROP_KILL_DEAD_CODE));
4345 if (! changed || ! try_optimize_cfg (CLEANUP_EXPENSIVE))
4348 delete_unreachable_blocks ();
4349 mark_critical_edges ();
4352 /* If asked, remove notes from the blocks we'll update. */
4353 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
4354 count_or_remove_death_notes (blocks, 1);
4359 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4361 basic_block bb = BASIC_BLOCK (i);
4363 COPY_REG_SET (tmp, bb->global_live_at_end);
4364 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4366 if (extent == UPDATE_LIFE_LOCAL)
4367 verify_local_live_at_start (tmp, bb);
4372 for (i = n_basic_blocks - 1; i >= 0; --i)
4374 basic_block bb = BASIC_BLOCK (i);
4376 COPY_REG_SET (tmp, bb->global_live_at_end);
4377 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4379 if (extent == UPDATE_LIFE_LOCAL)
4380 verify_local_live_at_start (tmp, bb);
4386 if (prop_flags & PROP_REG_INFO)
4388 /* The only pseudos that are live at the beginning of the function
4389 are those that were not set anywhere in the function. local-alloc
4390 doesn't know how to handle these correctly, so mark them as not
4391 local to any one basic block. */
4392 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
4393 FIRST_PSEUDO_REGISTER, i,
4394 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4396 /* We have a problem with any pseudoreg that lives across the setjmp.
4397 ANSI says that if a user variable does not change in value between
4398 the setjmp and the longjmp, then the longjmp preserves it. This
4399 includes longjmp from a place where the pseudo appears dead.
4400 (In principle, the value still exists if it is in scope.)
4401 If the pseudo goes in a hard reg, some other value may occupy
4402 that hard reg where this pseudo is dead, thus clobbering the pseudo.
4403 Conclusion: such a pseudo must not go in a hard reg. */
4404 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
4405 FIRST_PSEUDO_REGISTER, i,
4407 if (regno_reg_rtx[i] != 0)
4409 REG_LIVE_LENGTH (i) = -1;
4410 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4416 /* Free the variables allocated by find_basic_blocks.
4418 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
4421 free_basic_block_vars (keep_head_end_p)
4422 int keep_head_end_p;
4424 if (basic_block_for_insn)
4426 VARRAY_FREE (basic_block_for_insn);
4427 basic_block_for_insn = NULL;
4430 if (! keep_head_end_p)
4432 if (basic_block_info)
4435 VARRAY_FREE (basic_block_info);
4439 ENTRY_BLOCK_PTR->aux = NULL;
4440 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
4441 EXIT_BLOCK_PTR->aux = NULL;
4442 EXIT_BLOCK_PTR->global_live_at_start = NULL;
4446 /* Delete any insns that copy a register to itself. */
4449 delete_noop_moves (f)
4450 rtx f ATTRIBUTE_UNUSED;
4456 for (i = 0; i < n_basic_blocks; i++)
4458 bb = BASIC_BLOCK (i);
4459 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
4461 next = NEXT_INSN (insn);
4462 if (INSN_P (insn) && noop_move_p (insn))
4464 /* Do not call flow_delete_insn here to not confuse backward
4465 pointers of LIBCALL block. */
4466 PUT_CODE (insn, NOTE);
4467 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
4468 NOTE_SOURCE_FILE (insn) = 0;
4474 /* Delete any jump tables never referenced. We can't delete them at the
4475 time of removing tablejump insn as they are referenced by the preceeding
4476 insns computing the destination, so we delay deleting and garbagecollect
4477 them once life information is computed. */
4479 delete_dead_jumptables ()
4482 for (insn = get_insns (); insn; insn = next)
4484 next = NEXT_INSN (insn);
4485 if (GET_CODE (insn) == CODE_LABEL
4486 && LABEL_NUSES (insn) == 0
4487 && GET_CODE (next) == JUMP_INSN
4488 && (GET_CODE (PATTERN (next)) == ADDR_VEC
4489 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
4492 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
4493 flow_delete_insn (NEXT_INSN (insn));
4494 flow_delete_insn (insn);
4495 next = NEXT_INSN (next);
4500 /* Determine if the stack pointer is constant over the life of the function.
4501 Only useful before prologues have been emitted. */
4504 notice_stack_pointer_modification_1 (x, pat, data)
4506 rtx pat ATTRIBUTE_UNUSED;
4507 void *data ATTRIBUTE_UNUSED;
4509 if (x == stack_pointer_rtx
4510 /* The stack pointer is only modified indirectly as the result
4511 of a push until later in flow. See the comments in rtl.texi
4512 regarding Embedded Side-Effects on Addresses. */
4513 || (GET_CODE (x) == MEM
4514 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
4515 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
4516 current_function_sp_is_unchanging = 0;
4520 notice_stack_pointer_modification (f)
4525 /* Assume that the stack pointer is unchanging if alloca hasn't
4527 current_function_sp_is_unchanging = !current_function_calls_alloca;
4528 if (! current_function_sp_is_unchanging)
4531 for (insn = f; insn; insn = NEXT_INSN (insn))
4535 /* Check if insn modifies the stack pointer. */
4536 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
4538 if (! current_function_sp_is_unchanging)
4544 /* Mark a register in SET. Hard registers in large modes get all
4545 of their component registers set as well. */
4548 mark_reg (reg, xset)
4552 regset set = (regset) xset;
4553 int regno = REGNO (reg);
4555 if (GET_MODE (reg) == BLKmode)
4558 SET_REGNO_REG_SET (set, regno);
4559 if (regno < FIRST_PSEUDO_REGISTER)
4561 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
4563 SET_REGNO_REG_SET (set, regno + n);
4567 /* Mark those regs which are needed at the end of the function as live
4568 at the end of the last basic block. */
4571 mark_regs_live_at_end (set)
4576 /* If exiting needs the right stack value, consider the stack pointer
4577 live at the end of the function. */
4578 if ((HAVE_epilogue && reload_completed)
4579 || ! EXIT_IGNORE_STACK
4580 || (! FRAME_POINTER_REQUIRED
4581 && ! current_function_calls_alloca
4582 && flag_omit_frame_pointer)
4583 || current_function_sp_is_unchanging)
4585 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
4588 /* Mark the frame pointer if needed at the end of the function. If
4589 we end up eliminating it, it will be removed from the live list
4590 of each basic block by reload. */
4592 if (! reload_completed || frame_pointer_needed)
4594 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
4595 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4596 /* If they are different, also mark the hard frame pointer as live. */
4597 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
4598 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
4602 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
4603 /* Many architectures have a GP register even without flag_pic.
4604 Assume the pic register is not in use, or will be handled by
4605 other means, if it is not fixed. */
4606 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4607 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4608 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
4611 /* Mark all global registers, and all registers used by the epilogue
4612 as being live at the end of the function since they may be
4613 referenced by our caller. */
4614 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4615 if (global_regs[i] || EPILOGUE_USES (i))
4616 SET_REGNO_REG_SET (set, i);
4618 if (HAVE_epilogue && reload_completed)
4620 /* Mark all call-saved registers that we actually used. */
4621 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4622 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
4623 SET_REGNO_REG_SET (set, i);
4626 #ifdef EH_RETURN_DATA_REGNO
4627 /* Mark the registers that will contain data for the handler. */
4628 if (reload_completed && current_function_calls_eh_return)
4631 unsigned regno = EH_RETURN_DATA_REGNO(i);
4632 if (regno == INVALID_REGNUM)
4634 SET_REGNO_REG_SET (set, regno);
4637 #ifdef EH_RETURN_STACKADJ_RTX
4638 if ((! HAVE_epilogue || ! reload_completed)
4639 && current_function_calls_eh_return)
4641 rtx tmp = EH_RETURN_STACKADJ_RTX;
4642 if (tmp && REG_P (tmp))
4643 mark_reg (tmp, set);
4646 #ifdef EH_RETURN_HANDLER_RTX
4647 if ((! HAVE_epilogue || ! reload_completed)
4648 && current_function_calls_eh_return)
4650 rtx tmp = EH_RETURN_HANDLER_RTX;
4651 if (tmp && REG_P (tmp))
4652 mark_reg (tmp, set);
4656 /* Mark function return value. */
4657 diddle_return_value (mark_reg, set);
4660 /* Callback function for for_each_successor_phi. DATA is a regset.
4661 Sets the SRC_REGNO, the regno of the phi alternative for phi node
4662 INSN, in the regset. */
4665 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
4666 rtx insn ATTRIBUTE_UNUSED;
4667 int dest_regno ATTRIBUTE_UNUSED;
4671 regset live = (regset) data;
4672 SET_REGNO_REG_SET (live, src_regno);
4676 /* Propagate global life info around the graph of basic blocks. Begin
4677 considering blocks with their corresponding bit set in BLOCKS_IN.
4678 If BLOCKS_IN is null, consider it the universal set.
4680 BLOCKS_OUT is set for every block that was changed. */
4683 calculate_global_regs_live (blocks_in, blocks_out, flags)
4684 sbitmap blocks_in, blocks_out;
4687 basic_block *queue, *qhead, *qtail, *qend;
4688 regset tmp, new_live_at_end, call_used;
4689 regset_head tmp_head, call_used_head;
4690 regset_head new_live_at_end_head;
4693 tmp = INITIALIZE_REG_SET (tmp_head);
4694 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
4695 call_used = INITIALIZE_REG_SET (call_used_head);
4697 /* Inconveniently, this is only redily available in hard reg set form. */
4698 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
4699 if (call_used_regs[i])
4700 SET_REGNO_REG_SET (call_used, i);
4702 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
4703 because the `head == tail' style test for an empty queue doesn't
4704 work with a full queue. */
4705 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
4707 qhead = qend = queue + n_basic_blocks + 2;
4709 /* Queue the blocks set in the initial mask. Do this in reverse block
4710 number order so that we are more likely for the first round to do
4711 useful work. We use AUX non-null to flag that the block is queued. */
4714 /* Clear out the garbage that might be hanging out in bb->aux. */
4715 for (i = n_basic_blocks - 1; i >= 0; --i)
4716 BASIC_BLOCK (i)->aux = NULL;
4718 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
4720 basic_block bb = BASIC_BLOCK (i);
4727 for (i = 0; i < n_basic_blocks; ++i)
4729 basic_block bb = BASIC_BLOCK (i);
4736 sbitmap_zero (blocks_out);
4738 /* We work through the queue until there are no more blocks. What
4739 is live at the end of this block is precisely the union of what
4740 is live at the beginning of all its successors. So, we set its
4741 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
4742 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
4743 this block by walking through the instructions in this block in
4744 reverse order and updating as we go. If that changed
4745 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
4746 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
4748 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
4749 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
4750 must either be live at the end of the block, or used within the
4751 block. In the latter case, it will certainly never disappear
4752 from GLOBAL_LIVE_AT_START. In the former case, the register
4753 could go away only if it disappeared from GLOBAL_LIVE_AT_START
4754 for one of the successor blocks. By induction, that cannot
4756 while (qhead != qtail)
4758 int rescan, changed;
4767 /* Begin by propagating live_at_start from the successor blocks. */
4768 CLEAR_REG_SET (new_live_at_end);
4769 for (e = bb->succ; e; e = e->succ_next)
4771 basic_block sb = e->dest;
4773 /* Call-clobbered registers die across exception and call edges. */
4774 /* ??? Abnormal call edges ignored for the moment, as this gets
4775 confused by sibling call edges, which crashes reg-stack. */
4776 if (e->flags & EDGE_EH)
4778 bitmap_operation (tmp, sb->global_live_at_start,
4779 call_used, BITMAP_AND_COMPL);
4780 IOR_REG_SET (new_live_at_end, tmp);
4783 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
4786 /* The all-important stack pointer must always be live. */
4787 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
4789 /* Before reload, there are a few registers that must be forced
4790 live everywhere -- which might not already be the case for
4791 blocks within infinite loops. */
4792 if (! reload_completed)
4794 /* Any reference to any pseudo before reload is a potential
4795 reference of the frame pointer. */
4796 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
4798 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4799 /* Pseudos with argument area equivalences may require
4800 reloading via the argument pointer. */
4801 if (fixed_regs[ARG_POINTER_REGNUM])
4802 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
4805 /* Any constant, or pseudo with constant equivalences, may
4806 require reloading from memory using the pic register. */
4807 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4808 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4809 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
4812 /* Regs used in phi nodes are not included in
4813 global_live_at_start, since they are live only along a
4814 particular edge. Set those regs that are live because of a
4815 phi node alternative corresponding to this particular block. */
4817 for_each_successor_phi (bb, &set_phi_alternative_reg,
4820 if (bb == ENTRY_BLOCK_PTR)
4822 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4826 /* On our first pass through this block, we'll go ahead and continue.
4827 Recognize first pass by local_set NULL. On subsequent passes, we
4828 get to skip out early if live_at_end wouldn't have changed. */
4830 if (bb->local_set == NULL)
4832 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4833 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4838 /* If any bits were removed from live_at_end, we'll have to
4839 rescan the block. This wouldn't be necessary if we had
4840 precalculated local_live, however with PROP_SCAN_DEAD_CODE
4841 local_live is really dependent on live_at_end. */
4842 CLEAR_REG_SET (tmp);
4843 rescan = bitmap_operation (tmp, bb->global_live_at_end,
4844 new_live_at_end, BITMAP_AND_COMPL);
4848 /* If any of the registers in the new live_at_end set are
4849 conditionally set in this basic block, we must rescan.
4850 This is because conditional lifetimes at the end of the
4851 block do not just take the live_at_end set into account,
4852 but also the liveness at the start of each successor
4853 block. We can miss changes in those sets if we only
4854 compare the new live_at_end against the previous one. */
4855 CLEAR_REG_SET (tmp);
4856 rescan = bitmap_operation (tmp, new_live_at_end,
4857 bb->cond_local_set, BITMAP_AND);
4862 /* Find the set of changed bits. Take this opportunity
4863 to notice that this set is empty and early out. */
4864 CLEAR_REG_SET (tmp);
4865 changed = bitmap_operation (tmp, bb->global_live_at_end,
4866 new_live_at_end, BITMAP_XOR);
4870 /* If any of the changed bits overlap with local_set,
4871 we'll have to rescan the block. Detect overlap by
4872 the AND with ~local_set turning off bits. */
4873 rescan = bitmap_operation (tmp, tmp, bb->local_set,
4878 /* Let our caller know that BB changed enough to require its
4879 death notes updated. */
4881 SET_BIT (blocks_out, bb->index);
4885 /* Add to live_at_start the set of all registers in
4886 new_live_at_end that aren't in the old live_at_end. */
4888 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
4890 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4892 changed = bitmap_operation (bb->global_live_at_start,
4893 bb->global_live_at_start,
4900 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4902 /* Rescan the block insn by insn to turn (a copy of) live_at_end
4903 into live_at_start. */
4904 propagate_block (bb, new_live_at_end, bb->local_set,
4905 bb->cond_local_set, flags);
4907 /* If live_at start didn't change, no need to go farther. */
4908 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
4911 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
4914 /* Queue all predecessors of BB so that we may re-examine
4915 their live_at_end. */
4916 for (e = bb->pred; e; e = e->pred_next)
4918 basic_block pb = e->src;
4919 if (pb->aux == NULL)
4930 FREE_REG_SET (new_live_at_end);
4931 FREE_REG_SET (call_used);
4935 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
4937 basic_block bb = BASIC_BLOCK (i);
4938 FREE_REG_SET (bb->local_set);
4939 FREE_REG_SET (bb->cond_local_set);
4944 for (i = n_basic_blocks - 1; i >= 0; --i)
4946 basic_block bb = BASIC_BLOCK (i);
4947 FREE_REG_SET (bb->local_set);
4948 FREE_REG_SET (bb->cond_local_set);
4955 /* Subroutines of life analysis. */
4957 /* Allocate the permanent data structures that represent the results
4958 of life analysis. Not static since used also for stupid life analysis. */
4961 allocate_bb_life_data ()
4965 for (i = 0; i < n_basic_blocks; i++)
4967 basic_block bb = BASIC_BLOCK (i);
4969 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4970 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4973 ENTRY_BLOCK_PTR->global_live_at_end
4974 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4975 EXIT_BLOCK_PTR->global_live_at_start
4976 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4978 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4982 allocate_reg_life_data ()
4986 max_regno = max_reg_num ();
4988 /* Recalculate the register space, in case it has grown. Old style
4989 vector oriented regsets would set regset_{size,bytes} here also. */
4990 allocate_reg_info (max_regno, FALSE, FALSE);
4992 /* Reset all the data we'll collect in propagate_block and its
4994 for (i = 0; i < max_regno; i++)
4998 REG_N_DEATHS (i) = 0;
4999 REG_N_CALLS_CROSSED (i) = 0;
5000 REG_LIVE_LENGTH (i) = 0;
5001 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
5005 /* Delete dead instructions for propagate_block. */
5008 propagate_block_delete_insn (bb, insn)
5012 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
5014 /* If the insn referred to a label, and that label was attached to
5015 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
5016 pretty much mandatory to delete it, because the ADDR_VEC may be
5017 referencing labels that no longer exist.
5019 INSN may reference a deleted label, particularly when a jump
5020 table has been optimized into a direct jump. There's no
5021 real good way to fix up the reference to the deleted label
5022 when the label is deleted, so we just allow it here.
5024 After dead code elimination is complete, we do search for
5025 any REG_LABEL notes which reference deleted labels as a
5028 if (inote && GET_CODE (inote) == CODE_LABEL)
5030 rtx label = XEXP (inote, 0);
5033 /* The label may be forced if it has been put in the constant
5034 pool. If that is the only use we must discard the table
5035 jump following it, but not the label itself. */
5036 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
5037 && (next = next_nonnote_insn (label)) != NULL
5038 && GET_CODE (next) == JUMP_INSN
5039 && (GET_CODE (PATTERN (next)) == ADDR_VEC
5040 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
5042 rtx pat = PATTERN (next);
5043 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
5044 int len = XVECLEN (pat, diff_vec_p);
5047 for (i = 0; i < len; i++)
5048 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
5050 flow_delete_insn (next);
5054 if (bb->end == insn)
5055 bb->end = PREV_INSN (insn);
5056 flow_delete_insn (insn);
5059 /* Delete dead libcalls for propagate_block. Return the insn
5060 before the libcall. */
5063 propagate_block_delete_libcall (bb, insn, note)
5067 rtx first = XEXP (note, 0);
5068 rtx before = PREV_INSN (first);
5070 if (insn == bb->end)
5073 flow_delete_insn_chain (first, insn);
5077 /* Update the life-status of regs for one insn. Return the previous insn. */
5080 propagate_one_insn (pbi, insn)
5081 struct propagate_block_info *pbi;
5084 rtx prev = PREV_INSN (insn);
5085 int flags = pbi->flags;
5086 int insn_is_dead = 0;
5087 int libcall_is_dead = 0;
5091 if (! INSN_P (insn))
5094 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
5095 if (flags & PROP_SCAN_DEAD_CODE)
5097 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
5098 libcall_is_dead = (insn_is_dead && note != 0
5099 && libcall_dead_p (pbi, note, insn));
5102 /* If an instruction consists of just dead store(s) on final pass,
5104 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
5106 /* If we're trying to delete a prologue or epilogue instruction
5107 that isn't flagged as possibly being dead, something is wrong.
5108 But if we are keeping the stack pointer depressed, we might well
5109 be deleting insns that are used to compute the amount to update
5110 it by, so they are fine. */
5111 if (reload_completed
5112 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
5113 && (TYPE_RETURNS_STACK_DEPRESSED
5114 (TREE_TYPE (current_function_decl))))
5115 && (((HAVE_epilogue || HAVE_prologue)
5116 && prologue_epilogue_contains (insn))
5117 || (HAVE_sibcall_epilogue
5118 && sibcall_epilogue_contains (insn)))
5119 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
5122 /* Record sets. Do this even for dead instructions, since they
5123 would have killed the values if they hadn't been deleted. */
5124 mark_set_regs (pbi, PATTERN (insn), insn);
5126 /* CC0 is now known to be dead. Either this insn used it,
5127 in which case it doesn't anymore, or clobbered it,
5128 so the next insn can't use it. */
5131 if (libcall_is_dead)
5132 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
5134 propagate_block_delete_insn (pbi->bb, insn);
5139 /* See if this is an increment or decrement that can be merged into
5140 a following memory address. */
5143 register rtx x = single_set (insn);
5145 /* Does this instruction increment or decrement a register? */
5146 if ((flags & PROP_AUTOINC)
5148 && GET_CODE (SET_DEST (x)) == REG
5149 && (GET_CODE (SET_SRC (x)) == PLUS
5150 || GET_CODE (SET_SRC (x)) == MINUS)
5151 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
5152 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
5153 /* Ok, look for a following memory ref we can combine with.
5154 If one is found, change the memory ref to a PRE_INC
5155 or PRE_DEC, cancel this insn, and return 1.
5156 Return 0 if nothing has been done. */
5157 && try_pre_increment_1 (pbi, insn))
5160 #endif /* AUTO_INC_DEC */
5162 CLEAR_REG_SET (pbi->new_set);
5164 /* If this is not the final pass, and this insn is copying the value of
5165 a library call and it's dead, don't scan the insns that perform the
5166 library call, so that the call's arguments are not marked live. */
5167 if (libcall_is_dead)
5169 /* Record the death of the dest reg. */
5170 mark_set_regs (pbi, PATTERN (insn), insn);
5172 insn = XEXP (note, 0);
5173 return PREV_INSN (insn);
5175 else if (GET_CODE (PATTERN (insn)) == SET
5176 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
5177 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
5178 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
5179 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
5180 /* We have an insn to pop a constant amount off the stack.
5181 (Such insns use PLUS regardless of the direction of the stack,
5182 and any insn to adjust the stack by a constant is always a pop.)
5183 These insns, if not dead stores, have no effect on life. */
5187 /* Any regs live at the time of a call instruction must not go
5188 in a register clobbered by calls. Find all regs now live and
5189 record this for them. */
5191 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
5192 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5193 { REG_N_CALLS_CROSSED (i)++; });
5195 /* Record sets. Do this even for dead instructions, since they
5196 would have killed the values if they hadn't been deleted. */
5197 mark_set_regs (pbi, PATTERN (insn), insn);
5199 if (GET_CODE (insn) == CALL_INSN)
5205 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5206 cond = COND_EXEC_TEST (PATTERN (insn));
5208 /* Non-constant calls clobber memory. */
5209 if (! CONST_CALL_P (insn))
5211 free_EXPR_LIST_list (&pbi->mem_set_list);
5212 pbi->mem_set_list_len = 0;
5215 /* There may be extra registers to be clobbered. */
5216 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5218 note = XEXP (note, 1))
5219 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
5220 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
5221 cond, insn, pbi->flags);
5223 /* Calls change all call-used and global registers. */
5224 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5225 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
5227 /* We do not want REG_UNUSED notes for these registers. */
5228 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
5230 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
5234 /* If an insn doesn't use CC0, it becomes dead since we assume
5235 that every insn clobbers it. So show it dead here;
5236 mark_used_regs will set it live if it is referenced. */
5241 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
5243 /* Sometimes we may have inserted something before INSN (such as a move)
5244 when we make an auto-inc. So ensure we will scan those insns. */
5246 prev = PREV_INSN (insn);
5249 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
5255 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5256 cond = COND_EXEC_TEST (PATTERN (insn));
5258 /* Calls use their arguments. */
5259 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5261 note = XEXP (note, 1))
5262 if (GET_CODE (XEXP (note, 0)) == USE)
5263 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
5266 /* The stack ptr is used (honorarily) by a CALL insn. */
5267 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
5269 /* Calls may also reference any of the global registers,
5270 so they are made live. */
5271 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5273 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
5278 /* On final pass, update counts of how many insns in which each reg
5280 if (flags & PROP_REG_INFO)
5281 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5282 { REG_LIVE_LENGTH (i)++; });
5287 /* Initialize a propagate_block_info struct for public consumption.
5288 Note that the structure itself is opaque to this file, but that
5289 the user can use the regsets provided here. */
5291 struct propagate_block_info *
5292 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
5294 regset live, local_set, cond_local_set;
5297 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
5300 pbi->reg_live = live;
5301 pbi->mem_set_list = NULL_RTX;
5302 pbi->mem_set_list_len = 0;
5303 pbi->local_set = local_set;
5304 pbi->cond_local_set = cond_local_set;
5308 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5309 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
5311 pbi->reg_next_use = NULL;
5313 pbi->new_set = BITMAP_XMALLOC ();
5315 #ifdef HAVE_conditional_execution
5316 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
5317 free_reg_cond_life_info);
5318 pbi->reg_cond_reg = BITMAP_XMALLOC ();
5320 /* If this block ends in a conditional branch, for each register live
5321 from one side of the branch and not the other, record the register
5322 as conditionally dead. */
5323 if (GET_CODE (bb->end) == JUMP_INSN
5324 && any_condjump_p (bb->end))
5326 regset_head diff_head;
5327 regset diff = INITIALIZE_REG_SET (diff_head);
5328 basic_block bb_true, bb_false;
5329 rtx cond_true, cond_false, set_src;
5332 /* Identify the successor blocks. */
5333 bb_true = bb->succ->dest;
5334 if (bb->succ->succ_next != NULL)
5336 bb_false = bb->succ->succ_next->dest;
5338 if (bb->succ->flags & EDGE_FALLTHRU)
5340 basic_block t = bb_false;
5344 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
5349 /* This can happen with a conditional jump to the next insn. */
5350 if (JUMP_LABEL (bb->end) != bb_true->head)
5353 /* Simplest way to do nothing. */
5357 /* Extract the condition from the branch. */
5358 set_src = SET_SRC (pc_set (bb->end));
5359 cond_true = XEXP (set_src, 0);
5360 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
5361 GET_MODE (cond_true), XEXP (cond_true, 0),
5362 XEXP (cond_true, 1));
5363 if (GET_CODE (XEXP (set_src, 1)) == PC)
5366 cond_false = cond_true;
5370 /* Compute which register lead different lives in the successors. */
5371 if (bitmap_operation (diff, bb_true->global_live_at_start,
5372 bb_false->global_live_at_start, BITMAP_XOR))
5374 rtx reg = XEXP (cond_true, 0);
5376 if (GET_CODE (reg) == SUBREG)
5377 reg = SUBREG_REG (reg);
5379 if (GET_CODE (reg) != REG)
5382 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
5384 /* For each such register, mark it conditionally dead. */
5385 EXECUTE_IF_SET_IN_REG_SET
5388 struct reg_cond_life_info *rcli;
5391 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5393 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
5397 rcli->condition = cond;
5398 rcli->stores = const0_rtx;
5399 rcli->orig_condition = cond;
5401 splay_tree_insert (pbi->reg_cond_dead, i,
5402 (splay_tree_value) rcli);
5406 FREE_REG_SET (diff);
5410 /* If this block has no successors, any stores to the frame that aren't
5411 used later in the block are dead. So make a pass over the block
5412 recording any such that are made and show them dead at the end. We do
5413 a very conservative and simple job here. */
5415 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
5416 && (TYPE_RETURNS_STACK_DEPRESSED
5417 (TREE_TYPE (current_function_decl))))
5418 && (flags & PROP_SCAN_DEAD_CODE)
5419 && (bb->succ == NULL
5420 || (bb->succ->succ_next == NULL
5421 && bb->succ->dest == EXIT_BLOCK_PTR
5422 && ! current_function_calls_eh_return)))
5425 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
5426 if (GET_CODE (insn) == INSN
5427 && (set = single_set (insn))
5428 && GET_CODE (SET_DEST (set)) == MEM)
5430 rtx mem = SET_DEST (set);
5431 rtx canon_mem = canon_rtx (mem);
5433 /* This optimization is performed by faking a store to the
5434 memory at the end of the block. This doesn't work for
5435 unchanging memories because multiple stores to unchanging
5436 memory is illegal and alias analysis doesn't consider it. */
5437 if (RTX_UNCHANGING_P (canon_mem))
5440 if (XEXP (canon_mem, 0) == frame_pointer_rtx
5441 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
5442 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
5443 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
5446 /* Store a copy of mem, otherwise the address may be scrogged
5447 by find_auto_inc. This matters because insn_dead_p uses
5448 an rtx_equal_p check to determine if two addresses are
5449 the same. This works before find_auto_inc, but fails
5450 after find_auto_inc, causing discrepencies between the
5451 set of live registers calculated during the
5452 calculate_global_regs_live phase and what actually exists
5453 after flow completes, leading to aborts. */
5454 if (flags & PROP_AUTOINC)
5455 mem = shallow_copy_rtx (mem);
5457 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
5458 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
5467 /* Release a propagate_block_info struct. */
5470 free_propagate_block_info (pbi)
5471 struct propagate_block_info *pbi;
5473 free_EXPR_LIST_list (&pbi->mem_set_list);
5475 BITMAP_XFREE (pbi->new_set);
5477 #ifdef HAVE_conditional_execution
5478 splay_tree_delete (pbi->reg_cond_dead);
5479 BITMAP_XFREE (pbi->reg_cond_reg);
5482 if (pbi->reg_next_use)
5483 free (pbi->reg_next_use);
5488 /* Compute the registers live at the beginning of a basic block BB from
5489 those live at the end.
5491 When called, REG_LIVE contains those live at the end. On return, it
5492 contains those live at the beginning.
5494 LOCAL_SET, if non-null, will be set with all registers killed
5495 unconditionally by this basic block.
5496 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
5497 killed conditionally by this basic block. If there is any unconditional
5498 set of a register, then the corresponding bit will be set in LOCAL_SET
5499 and cleared in COND_LOCAL_SET.
5500 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
5501 case, the resulting set will be equal to the union of the two sets that
5502 would otherwise be computed.
5504 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
5507 propagate_block (bb, live, local_set, cond_local_set, flags)
5511 regset cond_local_set;
5514 struct propagate_block_info *pbi;
5518 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
5520 if (flags & PROP_REG_INFO)
5524 /* Process the regs live at the end of the block.
5525 Mark them as not local to any one basic block. */
5526 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
5527 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
5530 /* Scan the block an insn at a time from end to beginning. */
5533 for (insn = bb->end;; insn = prev)
5535 /* If this is a call to `setjmp' et al, warn if any
5536 non-volatile datum is live. */
5537 if ((flags & PROP_REG_INFO)
5538 && GET_CODE (insn) == NOTE
5539 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
5540 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
5542 prev = propagate_one_insn (pbi, insn);
5543 changed |= NEXT_INSN (prev) != insn;
5545 if (insn == bb->head)
5549 free_propagate_block_info (pbi);
5554 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
5555 (SET expressions whose destinations are registers dead after the insn).
5556 NEEDED is the regset that says which regs are alive after the insn.
5558 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
5560 If X is the entire body of an insn, NOTES contains the reg notes
5561 pertaining to the insn. */
5564 insn_dead_p (pbi, x, call_ok, notes)
5565 struct propagate_block_info *pbi;
5568 rtx notes ATTRIBUTE_UNUSED;
5570 enum rtx_code code = GET_CODE (x);
5573 /* If flow is invoked after reload, we must take existing AUTO_INC
5574 expresions into account. */
5575 if (reload_completed)
5577 for (; notes; notes = XEXP (notes, 1))
5579 if (REG_NOTE_KIND (notes) == REG_INC)
5581 int regno = REGNO (XEXP (notes, 0));
5583 /* Don't delete insns to set global regs. */
5584 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5585 || REGNO_REG_SET_P (pbi->reg_live, regno))
5592 /* If setting something that's a reg or part of one,
5593 see if that register's altered value will be live. */
5597 rtx r = SET_DEST (x);
5600 if (GET_CODE (r) == CC0)
5601 return ! pbi->cc0_live;
5604 /* A SET that is a subroutine call cannot be dead. */
5605 if (GET_CODE (SET_SRC (x)) == CALL)
5611 /* Don't eliminate loads from volatile memory or volatile asms. */
5612 else if (volatile_refs_p (SET_SRC (x)))
5615 if (GET_CODE (r) == MEM)
5619 if (MEM_VOLATILE_P (r))
5622 /* Walk the set of memory locations we are currently tracking
5623 and see if one is an identical match to this memory location.
5624 If so, this memory write is dead (remember, we're walking
5625 backwards from the end of the block to the start). Since
5626 rtx_equal_p does not check the alias set or flags, we also
5627 must have the potential for them to conflict (anti_dependence). */
5628 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
5629 if (anti_dependence (r, XEXP (temp, 0)))
5631 rtx mem = XEXP (temp, 0);
5633 if (rtx_equal_p (mem, r))
5636 /* Check if memory reference matches an auto increment. Only
5637 post increment/decrement or modify are valid. */
5638 if (GET_MODE (mem) == GET_MODE (r)
5639 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
5640 || GET_CODE (XEXP (mem, 0)) == POST_INC
5641 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
5642 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
5643 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
5650 while (GET_CODE (r) == SUBREG
5651 || GET_CODE (r) == STRICT_LOW_PART
5652 || GET_CODE (r) == ZERO_EXTRACT)
5655 if (GET_CODE (r) == REG)
5657 int regno = REGNO (r);
5660 if (REGNO_REG_SET_P (pbi->reg_live, regno))
5663 /* If this is a hard register, verify that subsequent
5664 words are not needed. */
5665 if (regno < FIRST_PSEUDO_REGISTER)
5667 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
5670 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
5674 /* Don't delete insns to set global regs. */
5675 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5678 /* Make sure insns to set the stack pointer aren't deleted. */
5679 if (regno == STACK_POINTER_REGNUM)
5682 /* ??? These bits might be redundant with the force live bits
5683 in calculate_global_regs_live. We would delete from
5684 sequential sets; whether this actually affects real code
5685 for anything but the stack pointer I don't know. */
5686 /* Make sure insns to set the frame pointer aren't deleted. */
5687 if (regno == FRAME_POINTER_REGNUM
5688 && (! reload_completed || frame_pointer_needed))
5690 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5691 if (regno == HARD_FRAME_POINTER_REGNUM
5692 && (! reload_completed || frame_pointer_needed))
5696 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5697 /* Make sure insns to set arg pointer are never deleted
5698 (if the arg pointer isn't fixed, there will be a USE
5699 for it, so we can treat it normally). */
5700 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5704 /* Otherwise, the set is dead. */
5710 /* If performing several activities, insn is dead if each activity
5711 is individually dead. Also, CLOBBERs and USEs can be ignored; a
5712 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
5714 else if (code == PARALLEL)
5716 int i = XVECLEN (x, 0);
5718 for (i--; i >= 0; i--)
5719 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
5720 && GET_CODE (XVECEXP (x, 0, i)) != USE
5721 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
5727 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
5728 is not necessarily true for hard registers. */
5729 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
5730 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
5731 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
5734 /* We do not check other CLOBBER or USE here. An insn consisting of just
5735 a CLOBBER or just a USE should not be deleted. */
5739 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
5740 return 1 if the entire library call is dead.
5741 This is true if INSN copies a register (hard or pseudo)
5742 and if the hard return reg of the call insn is dead.
5743 (The caller should have tested the destination of the SET inside
5744 INSN already for death.)
5746 If this insn doesn't just copy a register, then we don't
5747 have an ordinary libcall. In that case, cse could not have
5748 managed to substitute the source for the dest later on,
5749 so we can assume the libcall is dead.
5751 PBI is the block info giving pseudoregs live before this insn.
5752 NOTE is the REG_RETVAL note of the insn. */
5755 libcall_dead_p (pbi, note, insn)
5756 struct propagate_block_info *pbi;
5760 rtx x = single_set (insn);
5764 register rtx r = SET_SRC (x);
5765 if (GET_CODE (r) == REG)
5767 rtx call = XEXP (note, 0);
5771 /* Find the call insn. */
5772 while (call != insn && GET_CODE (call) != CALL_INSN)
5773 call = NEXT_INSN (call);
5775 /* If there is none, do nothing special,
5776 since ordinary death handling can understand these insns. */
5780 /* See if the hard reg holding the value is dead.
5781 If this is a PARALLEL, find the call within it. */
5782 call_pat = PATTERN (call);
5783 if (GET_CODE (call_pat) == PARALLEL)
5785 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
5786 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
5787 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
5790 /* This may be a library call that is returning a value
5791 via invisible pointer. Do nothing special, since
5792 ordinary death handling can understand these insns. */
5796 call_pat = XVECEXP (call_pat, 0, i);
5799 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
5805 /* Return 1 if register REGNO was used before it was set, i.e. if it is
5806 live at function entry. Don't count global register variables, variables
5807 in registers that can be used for function arg passing, or variables in
5808 fixed hard registers. */
5811 regno_uninitialized (regno)
5814 if (n_basic_blocks == 0
5815 || (regno < FIRST_PSEUDO_REGISTER
5816 && (global_regs[regno]
5817 || fixed_regs[regno]
5818 || FUNCTION_ARG_REGNO_P (regno))))
5821 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
5824 /* 1 if register REGNO was alive at a place where `setjmp' was called
5825 and was set more than once or is an argument.
5826 Such regs may be clobbered by `longjmp'. */
5829 regno_clobbered_at_setjmp (regno)
5832 if (n_basic_blocks == 0)
5835 return ((REG_N_SETS (regno) > 1
5836 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
5837 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
5840 /* INSN references memory, possibly using autoincrement addressing modes.
5841 Find any entries on the mem_set_list that need to be invalidated due
5842 to an address change. */
5845 invalidate_mems_from_autoinc (pbi, insn)
5846 struct propagate_block_info *pbi;
5849 rtx note = REG_NOTES (insn);
5850 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
5852 if (REG_NOTE_KIND (note) == REG_INC)
5854 rtx temp = pbi->mem_set_list;
5855 rtx prev = NULL_RTX;
5860 next = XEXP (temp, 1);
5861 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
5863 /* Splice temp out of list. */
5865 XEXP (prev, 1) = next;
5867 pbi->mem_set_list = next;
5868 free_EXPR_LIST_node (temp);
5869 pbi->mem_set_list_len--;
5879 /* EXP is either a MEM or a REG. Remove any dependant entries
5880 from pbi->mem_set_list. */
5883 invalidate_mems_from_set (pbi, exp)
5884 struct propagate_block_info *pbi;
5887 rtx temp = pbi->mem_set_list;
5888 rtx prev = NULL_RTX;
5893 next = XEXP (temp, 1);
5894 if ((GET_CODE (exp) == MEM
5895 && output_dependence (XEXP (temp, 0), exp))
5896 || (GET_CODE (exp) == REG
5897 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
5899 /* Splice this entry out of the list. */
5901 XEXP (prev, 1) = next;
5903 pbi->mem_set_list = next;
5904 free_EXPR_LIST_node (temp);
5905 pbi->mem_set_list_len--;
5913 /* Process the registers that are set within X. Their bits are set to
5914 1 in the regset DEAD, because they are dead prior to this insn.
5916 If INSN is nonzero, it is the insn being processed.
5918 FLAGS is the set of operations to perform. */
5921 mark_set_regs (pbi, x, insn)
5922 struct propagate_block_info *pbi;
5925 rtx cond = NULL_RTX;
5930 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
5932 if (REG_NOTE_KIND (link) == REG_INC)
5933 mark_set_1 (pbi, SET, XEXP (link, 0),
5934 (GET_CODE (x) == COND_EXEC
5935 ? COND_EXEC_TEST (x) : NULL_RTX),
5939 switch (code = GET_CODE (x))
5943 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
5947 cond = COND_EXEC_TEST (x);
5948 x = COND_EXEC_CODE (x);
5954 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
5956 rtx sub = XVECEXP (x, 0, i);
5957 switch (code = GET_CODE (sub))
5960 if (cond != NULL_RTX)
5963 cond = COND_EXEC_TEST (sub);
5964 sub = COND_EXEC_CODE (sub);
5965 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
5971 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
5986 /* Process a single set, which appears in INSN. REG (which may not
5987 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
5988 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
5989 If the set is conditional (because it appear in a COND_EXEC), COND
5990 will be the condition. */
5993 mark_set_1 (pbi, code, reg, cond, insn, flags)
5994 struct propagate_block_info *pbi;
5996 rtx reg, cond, insn;
5999 int regno_first = -1, regno_last = -1;
6000 unsigned long not_dead = 0;
6003 /* Modifying just one hardware register of a multi-reg value or just a
6004 byte field of a register does not mean the value from before this insn
6005 is now dead. Of course, if it was dead after it's unused now. */
6007 switch (GET_CODE (reg))
6010 /* Some targets place small structures in registers for return values of
6011 functions. We have to detect this case specially here to get correct
6012 flow information. */
6013 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
6014 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
6015 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
6021 case STRICT_LOW_PART:
6022 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
6024 reg = XEXP (reg, 0);
6025 while (GET_CODE (reg) == SUBREG
6026 || GET_CODE (reg) == ZERO_EXTRACT
6027 || GET_CODE (reg) == SIGN_EXTRACT
6028 || GET_CODE (reg) == STRICT_LOW_PART);
6029 if (GET_CODE (reg) == MEM)
6031 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
6035 regno_last = regno_first = REGNO (reg);
6036 if (regno_first < FIRST_PSEUDO_REGISTER)
6037 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
6041 if (GET_CODE (SUBREG_REG (reg)) == REG)
6043 enum machine_mode outer_mode = GET_MODE (reg);
6044 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
6046 /* Identify the range of registers affected. This is moderately
6047 tricky for hard registers. See alter_subreg. */
6049 regno_last = regno_first = REGNO (SUBREG_REG (reg));
6050 if (regno_first < FIRST_PSEUDO_REGISTER)
6052 regno_first += subreg_regno_offset (regno_first, inner_mode,
6055 regno_last = (regno_first
6056 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
6058 /* Since we've just adjusted the register number ranges, make
6059 sure REG matches. Otherwise some_was_live will be clear
6060 when it shouldn't have been, and we'll create incorrect
6061 REG_UNUSED notes. */
6062 reg = gen_rtx_REG (outer_mode, regno_first);
6066 /* If the number of words in the subreg is less than the number
6067 of words in the full register, we have a well-defined partial
6068 set. Otherwise the high bits are undefined.
6070 This is only really applicable to pseudos, since we just took
6071 care of multi-word hard registers. */
6072 if (((GET_MODE_SIZE (outer_mode)
6073 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
6074 < ((GET_MODE_SIZE (inner_mode)
6075 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
6076 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
6079 reg = SUBREG_REG (reg);
6083 reg = SUBREG_REG (reg);
6090 /* If this set is a MEM, then it kills any aliased writes.
6091 If this set is a REG, then it kills any MEMs which use the reg. */
6092 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
6094 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
6095 invalidate_mems_from_set (pbi, reg);
6097 /* If the memory reference had embedded side effects (autoincrement
6098 address modes. Then we may need to kill some entries on the
6100 if (insn && GET_CODE (reg) == MEM)
6101 invalidate_mems_from_autoinc (pbi, insn);
6103 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
6104 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
6105 /* ??? With more effort we could track conditional memory life. */
6107 /* We do not know the size of a BLKmode store, so we do not track
6108 them for redundant store elimination. */
6109 && GET_MODE (reg) != BLKmode
6110 /* There are no REG_INC notes for SP, so we can't assume we'll see
6111 everything that invalidates it. To be safe, don't eliminate any
6112 stores though SP; none of them should be redundant anyway. */
6113 && ! reg_mentioned_p (stack_pointer_rtx, reg))
6116 /* Store a copy of mem, otherwise the address may be
6117 scrogged by find_auto_inc. */
6118 if (flags & PROP_AUTOINC)
6119 reg = shallow_copy_rtx (reg);
6121 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
6122 pbi->mem_set_list_len++;
6126 if (GET_CODE (reg) == REG
6127 && ! (regno_first == FRAME_POINTER_REGNUM
6128 && (! reload_completed || frame_pointer_needed))
6129 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
6130 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
6131 && (! reload_completed || frame_pointer_needed))
6133 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
6134 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
6138 int some_was_live = 0, some_was_dead = 0;
6140 for (i = regno_first; i <= regno_last; ++i)
6142 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
6145 /* Order of the set operation matters here since both
6146 sets may be the same. */
6147 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
6148 if (cond != NULL_RTX
6149 && ! REGNO_REG_SET_P (pbi->local_set, i))
6150 SET_REGNO_REG_SET (pbi->cond_local_set, i);
6152 SET_REGNO_REG_SET (pbi->local_set, i);
6154 if (code != CLOBBER)
6155 SET_REGNO_REG_SET (pbi->new_set, i);
6157 some_was_live |= needed_regno;
6158 some_was_dead |= ! needed_regno;
6161 #ifdef HAVE_conditional_execution
6162 /* Consider conditional death in deciding that the register needs
6164 if (some_was_live && ! not_dead
6165 /* The stack pointer is never dead. Well, not strictly true,
6166 but it's very difficult to tell from here. Hopefully
6167 combine_stack_adjustments will fix up the most egregious
6169 && regno_first != STACK_POINTER_REGNUM)
6171 for (i = regno_first; i <= regno_last; ++i)
6172 if (! mark_regno_cond_dead (pbi, i, cond))
6173 not_dead |= ((unsigned long) 1) << (i - regno_first);
6177 /* Additional data to record if this is the final pass. */
6178 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
6179 | PROP_DEATH_NOTES | PROP_AUTOINC))
6182 register int blocknum = pbi->bb->index;
6185 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6187 y = pbi->reg_next_use[regno_first];
6189 /* The next use is no longer next, since a store intervenes. */
6190 for (i = regno_first; i <= regno_last; ++i)
6191 pbi->reg_next_use[i] = 0;
6194 if (flags & PROP_REG_INFO)
6196 for (i = regno_first; i <= regno_last; ++i)
6198 /* Count (weighted) references, stores, etc. This counts a
6199 register twice if it is modified, but that is correct. */
6200 REG_N_SETS (i) += 1;
6201 REG_N_REFS (i) += 1;
6202 REG_FREQ (i) += (optimize_size || !pbi->bb->frequency
6203 ? 1 : pbi->bb->frequency);
6205 /* The insns where a reg is live are normally counted
6206 elsewhere, but we want the count to include the insn
6207 where the reg is set, and the normal counting mechanism
6208 would not count it. */
6209 REG_LIVE_LENGTH (i) += 1;
6212 /* If this is a hard reg, record this function uses the reg. */
6213 if (regno_first < FIRST_PSEUDO_REGISTER)
6215 for (i = regno_first; i <= regno_last; i++)
6216 regs_ever_live[i] = 1;
6220 /* Keep track of which basic blocks each reg appears in. */
6221 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6222 REG_BASIC_BLOCK (regno_first) = blocknum;
6223 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6224 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6228 if (! some_was_dead)
6230 if (flags & PROP_LOG_LINKS)
6232 /* Make a logical link from the next following insn
6233 that uses this register, back to this insn.
6234 The following insns have already been processed.
6236 We don't build a LOG_LINK for hard registers containing
6237 in ASM_OPERANDs. If these registers get replaced,
6238 we might wind up changing the semantics of the insn,
6239 even if reload can make what appear to be valid
6240 assignments later. */
6241 if (y && (BLOCK_NUM (y) == blocknum)
6242 && (regno_first >= FIRST_PSEUDO_REGISTER
6243 || asm_noperands (PATTERN (y)) < 0))
6244 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
6249 else if (! some_was_live)
6251 if (flags & PROP_REG_INFO)
6252 REG_N_DEATHS (regno_first) += 1;
6254 if (flags & PROP_DEATH_NOTES)
6256 /* Note that dead stores have already been deleted
6257 when possible. If we get here, we have found a
6258 dead store that cannot be eliminated (because the
6259 same insn does something useful). Indicate this
6260 by marking the reg being set as dying here. */
6262 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6267 if (flags & PROP_DEATH_NOTES)
6269 /* This is a case where we have a multi-word hard register
6270 and some, but not all, of the words of the register are
6271 needed in subsequent insns. Write REG_UNUSED notes
6272 for those parts that were not needed. This case should
6275 for (i = regno_first; i <= regno_last; ++i)
6276 if (! REGNO_REG_SET_P (pbi->reg_live, i))
6278 = alloc_EXPR_LIST (REG_UNUSED,
6279 gen_rtx_REG (reg_raw_mode[i], i),
6285 /* Mark the register as being dead. */
6287 /* The stack pointer is never dead. Well, not strictly true,
6288 but it's very difficult to tell from here. Hopefully
6289 combine_stack_adjustments will fix up the most egregious
6291 && regno_first != STACK_POINTER_REGNUM)
6293 for (i = regno_first; i <= regno_last; ++i)
6294 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
6295 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
6298 else if (GET_CODE (reg) == REG)
6300 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6301 pbi->reg_next_use[regno_first] = 0;
6304 /* If this is the last pass and this is a SCRATCH, show it will be dying
6305 here and count it. */
6306 else if (GET_CODE (reg) == SCRATCH)
6308 if (flags & PROP_DEATH_NOTES)
6310 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6314 #ifdef HAVE_conditional_execution
6315 /* Mark REGNO conditionally dead.
6316 Return true if the register is now unconditionally dead. */
6319 mark_regno_cond_dead (pbi, regno, cond)
6320 struct propagate_block_info *pbi;
6324 /* If this is a store to a predicate register, the value of the
6325 predicate is changing, we don't know that the predicate as seen
6326 before is the same as that seen after. Flush all dependent
6327 conditions from reg_cond_dead. This will make all such
6328 conditionally live registers unconditionally live. */
6329 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
6330 flush_reg_cond_reg (pbi, regno);
6332 /* If this is an unconditional store, remove any conditional
6333 life that may have existed. */
6334 if (cond == NULL_RTX)
6335 splay_tree_remove (pbi->reg_cond_dead, regno);
6338 splay_tree_node node;
6339 struct reg_cond_life_info *rcli;
6342 /* Otherwise this is a conditional set. Record that fact.
6343 It may have been conditionally used, or there may be a
6344 subsequent set with a complimentary condition. */
6346 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
6349 /* The register was unconditionally live previously.
6350 Record the current condition as the condition under
6351 which it is dead. */
6352 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6353 rcli->condition = cond;
6354 rcli->stores = cond;
6355 rcli->orig_condition = const0_rtx;
6356 splay_tree_insert (pbi->reg_cond_dead, regno,
6357 (splay_tree_value) rcli);
6359 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6361 /* Not unconditionaly dead. */
6366 /* The register was conditionally live previously.
6367 Add the new condition to the old. */
6368 rcli = (struct reg_cond_life_info *) node->value;
6369 ncond = rcli->condition;
6370 ncond = ior_reg_cond (ncond, cond, 1);
6371 if (rcli->stores == const0_rtx)
6372 rcli->stores = cond;
6373 else if (rcli->stores != const1_rtx)
6374 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
6376 /* If the register is now unconditionally dead, remove the entry
6377 in the splay_tree. A register is unconditionally dead if the
6378 dead condition ncond is true. A register is also unconditionally
6379 dead if the sum of all conditional stores is an unconditional
6380 store (stores is true), and the dead condition is identically the
6381 same as the original dead condition initialized at the end of
6382 the block. This is a pointer compare, not an rtx_equal_p
6384 if (ncond == const1_rtx
6385 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
6386 splay_tree_remove (pbi->reg_cond_dead, regno);
6389 rcli->condition = ncond;
6391 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6393 /* Not unconditionaly dead. */
6402 /* Called from splay_tree_delete for pbi->reg_cond_life. */
6405 free_reg_cond_life_info (value)
6406 splay_tree_value value;
6408 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
6412 /* Helper function for flush_reg_cond_reg. */
6415 flush_reg_cond_reg_1 (node, data)
6416 splay_tree_node node;
6419 struct reg_cond_life_info *rcli;
6420 int *xdata = (int *) data;
6421 unsigned int regno = xdata[0];
6423 /* Don't need to search if last flushed value was farther on in
6424 the in-order traversal. */
6425 if (xdata[1] >= (int) node->key)
6428 /* Splice out portions of the expression that refer to regno. */
6429 rcli = (struct reg_cond_life_info *) node->value;
6430 rcli->condition = elim_reg_cond (rcli->condition, regno);
6431 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
6432 rcli->stores = elim_reg_cond (rcli->stores, regno);
6434 /* If the entire condition is now false, signal the node to be removed. */
6435 if (rcli->condition == const0_rtx)
6437 xdata[1] = node->key;
6440 else if (rcli->condition == const1_rtx)
6446 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
6449 flush_reg_cond_reg (pbi, regno)
6450 struct propagate_block_info *pbi;
6457 while (splay_tree_foreach (pbi->reg_cond_dead,
6458 flush_reg_cond_reg_1, pair) == -1)
6459 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
6461 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
6464 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
6465 For ior/and, the ADD flag determines whether we want to add the new
6466 condition X to the old one unconditionally. If it is zero, we will
6467 only return a new expression if X allows us to simplify part of
6468 OLD, otherwise we return OLD unchanged to the caller.
6469 If ADD is nonzero, we will return a new condition in all cases. The
6470 toplevel caller of one of these functions should always pass 1 for
6474 ior_reg_cond (old, x, add)
6480 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6482 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6483 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
6484 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6486 if (GET_CODE (x) == GET_CODE (old)
6487 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6491 return gen_rtx_IOR (0, old, x);
6494 switch (GET_CODE (old))
6497 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6498 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6499 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6501 if (op0 == const0_rtx)
6503 if (op1 == const0_rtx)
6505 if (op0 == const1_rtx || op1 == const1_rtx)
6507 if (op0 == XEXP (old, 0))
6508 op0 = gen_rtx_IOR (0, op0, x);
6510 op1 = gen_rtx_IOR (0, op1, x);
6511 return gen_rtx_IOR (0, op0, op1);
6515 return gen_rtx_IOR (0, old, x);
6518 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6519 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6520 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6522 if (op0 == const1_rtx)
6524 if (op1 == const1_rtx)
6526 if (op0 == const0_rtx || op1 == const0_rtx)
6528 if (op0 == XEXP (old, 0))
6529 op0 = gen_rtx_IOR (0, op0, x);
6531 op1 = gen_rtx_IOR (0, op1, x);
6532 return gen_rtx_AND (0, op0, op1);
6536 return gen_rtx_IOR (0, old, x);
6539 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6540 if (op0 != XEXP (old, 0))
6541 return not_reg_cond (op0);
6544 return gen_rtx_IOR (0, old, x);
6555 enum rtx_code x_code;
6557 if (x == const0_rtx)
6559 else if (x == const1_rtx)
6561 x_code = GET_CODE (x);
6564 if (GET_RTX_CLASS (x_code) == '<'
6565 && GET_CODE (XEXP (x, 0)) == REG)
6567 if (XEXP (x, 1) != const0_rtx)
6570 return gen_rtx_fmt_ee (reverse_condition (x_code),
6571 VOIDmode, XEXP (x, 0), const0_rtx);
6573 return gen_rtx_NOT (0, x);
6577 and_reg_cond (old, x, add)
6583 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6585 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6586 && GET_CODE (x) == reverse_condition (GET_CODE (old))
6587 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6589 if (GET_CODE (x) == GET_CODE (old)
6590 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6594 return gen_rtx_AND (0, old, x);
6597 switch (GET_CODE (old))
6600 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6601 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6602 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6604 if (op0 == const0_rtx)
6606 if (op1 == const0_rtx)
6608 if (op0 == const1_rtx || op1 == const1_rtx)
6610 if (op0 == XEXP (old, 0))
6611 op0 = gen_rtx_AND (0, op0, x);
6613 op1 = gen_rtx_AND (0, op1, x);
6614 return gen_rtx_IOR (0, op0, op1);
6618 return gen_rtx_AND (0, old, x);
6621 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6622 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6623 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6625 if (op0 == const1_rtx)
6627 if (op1 == const1_rtx)
6629 if (op0 == const0_rtx || op1 == const0_rtx)
6631 if (op0 == XEXP (old, 0))
6632 op0 = gen_rtx_AND (0, op0, x);
6634 op1 = gen_rtx_AND (0, op1, x);
6635 return gen_rtx_AND (0, op0, op1);
6640 /* If X is identical to one of the existing terms of the AND,
6641 then just return what we already have. */
6642 /* ??? There really should be some sort of recursive check here in
6643 case there are nested ANDs. */
6644 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
6645 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
6646 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
6647 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
6650 return gen_rtx_AND (0, old, x);
6653 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6654 if (op0 != XEXP (old, 0))
6655 return not_reg_cond (op0);
6658 return gen_rtx_AND (0, old, x);
6665 /* Given a condition X, remove references to reg REGNO and return the
6666 new condition. The removal will be done so that all conditions
6667 involving REGNO are considered to evaluate to false. This function
6668 is used when the value of REGNO changes. */
6671 elim_reg_cond (x, regno)
6677 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
6679 if (REGNO (XEXP (x, 0)) == regno)
6684 switch (GET_CODE (x))
6687 op0 = elim_reg_cond (XEXP (x, 0), regno);
6688 op1 = elim_reg_cond (XEXP (x, 1), regno);
6689 if (op0 == const0_rtx || op1 == const0_rtx)
6691 if (op0 == const1_rtx)
6693 if (op1 == const1_rtx)
6695 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6697 return gen_rtx_AND (0, op0, op1);
6700 op0 = elim_reg_cond (XEXP (x, 0), regno);
6701 op1 = elim_reg_cond (XEXP (x, 1), regno);
6702 if (op0 == const1_rtx || op1 == const1_rtx)
6704 if (op0 == const0_rtx)
6706 if (op1 == const0_rtx)
6708 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6710 return gen_rtx_IOR (0, op0, op1);
6713 op0 = elim_reg_cond (XEXP (x, 0), regno);
6714 if (op0 == const0_rtx)
6716 if (op0 == const1_rtx)
6718 if (op0 != XEXP (x, 0))
6719 return not_reg_cond (op0);
6726 #endif /* HAVE_conditional_execution */
6730 /* Try to substitute the auto-inc expression INC as the address inside
6731 MEM which occurs in INSN. Currently, the address of MEM is an expression
6732 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
6733 that has a single set whose source is a PLUS of INCR_REG and something
6737 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
6738 struct propagate_block_info *pbi;
6739 rtx inc, insn, mem, incr, incr_reg;
6741 int regno = REGNO (incr_reg);
6742 rtx set = single_set (incr);
6743 rtx q = SET_DEST (set);
6744 rtx y = SET_SRC (set);
6745 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
6747 /* Make sure this reg appears only once in this insn. */
6748 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
6751 if (dead_or_set_p (incr, incr_reg)
6752 /* Mustn't autoinc an eliminable register. */
6753 && (regno >= FIRST_PSEUDO_REGISTER
6754 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
6756 /* This is the simple case. Try to make the auto-inc. If
6757 we can't, we are done. Otherwise, we will do any
6758 needed updates below. */
6759 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
6762 else if (GET_CODE (q) == REG
6763 /* PREV_INSN used here to check the semi-open interval
6765 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
6766 /* We must also check for sets of q as q may be
6767 a call clobbered hard register and there may
6768 be a call between PREV_INSN (insn) and incr. */
6769 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
6771 /* We have *p followed sometime later by q = p+size.
6772 Both p and q must be live afterward,
6773 and q is not used between INSN and its assignment.
6774 Change it to q = p, ...*q..., q = q+size.
6775 Then fall into the usual case. */
6779 emit_move_insn (q, incr_reg);
6780 insns = get_insns ();
6783 if (basic_block_for_insn)
6784 for (temp = insns; temp; temp = NEXT_INSN (temp))
6785 set_block_for_insn (temp, pbi->bb);
6787 /* If we can't make the auto-inc, or can't make the
6788 replacement into Y, exit. There's no point in making
6789 the change below if we can't do the auto-inc and doing
6790 so is not correct in the pre-inc case. */
6793 validate_change (insn, &XEXP (mem, 0), inc, 1);
6794 validate_change (incr, &XEXP (y, opnum), q, 1);
6795 if (! apply_change_group ())
6798 /* We now know we'll be doing this change, so emit the
6799 new insn(s) and do the updates. */
6800 emit_insns_before (insns, insn);
6802 if (pbi->bb->head == insn)
6803 pbi->bb->head = insns;
6805 /* INCR will become a NOTE and INSN won't contain a
6806 use of INCR_REG. If a use of INCR_REG was just placed in
6807 the insn before INSN, make that the next use.
6808 Otherwise, invalidate it. */
6809 if (GET_CODE (PREV_INSN (insn)) == INSN
6810 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
6811 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
6812 pbi->reg_next_use[regno] = PREV_INSN (insn);
6814 pbi->reg_next_use[regno] = 0;
6819 /* REGNO is now used in INCR which is below INSN, but
6820 it previously wasn't live here. If we don't mark
6821 it as live, we'll put a REG_DEAD note for it
6822 on this insn, which is incorrect. */
6823 SET_REGNO_REG_SET (pbi->reg_live, regno);
6825 /* If there are any calls between INSN and INCR, show
6826 that REGNO now crosses them. */
6827 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
6828 if (GET_CODE (temp) == CALL_INSN)
6829 REG_N_CALLS_CROSSED (regno)++;
6834 /* If we haven't returned, it means we were able to make the
6835 auto-inc, so update the status. First, record that this insn
6836 has an implicit side effect. */
6838 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
6840 /* Modify the old increment-insn to simply copy
6841 the already-incremented value of our register. */
6842 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
6845 /* If that makes it a no-op (copying the register into itself) delete
6846 it so it won't appear to be a "use" and a "set" of this
6848 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
6850 /* If the original source was dead, it's dead now. */
6853 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
6855 remove_note (incr, note);
6856 if (XEXP (note, 0) != incr_reg)
6857 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
6860 PUT_CODE (incr, NOTE);
6861 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
6862 NOTE_SOURCE_FILE (incr) = 0;
6865 if (regno >= FIRST_PSEUDO_REGISTER)
6867 /* Count an extra reference to the reg. When a reg is
6868 incremented, spilling it is worse, so we want to make
6869 that less likely. */
6870 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
6871 ? 1 : pbi->bb->frequency);
6873 /* Count the increment as a setting of the register,
6874 even though it isn't a SET in rtl. */
6875 REG_N_SETS (regno)++;
6879 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
6883 find_auto_inc (pbi, x, insn)
6884 struct propagate_block_info *pbi;
6888 rtx addr = XEXP (x, 0);
6889 HOST_WIDE_INT offset = 0;
6890 rtx set, y, incr, inc_val;
6892 int size = GET_MODE_SIZE (GET_MODE (x));
6894 if (GET_CODE (insn) == JUMP_INSN)
6897 /* Here we detect use of an index register which might be good for
6898 postincrement, postdecrement, preincrement, or predecrement. */
6900 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
6901 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
6903 if (GET_CODE (addr) != REG)
6906 regno = REGNO (addr);
6908 /* Is the next use an increment that might make auto-increment? */
6909 incr = pbi->reg_next_use[regno];
6910 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
6912 set = single_set (incr);
6913 if (set == 0 || GET_CODE (set) != SET)
6917 if (GET_CODE (y) != PLUS)
6920 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
6921 inc_val = XEXP (y, 1);
6922 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
6923 inc_val = XEXP (y, 0);
6927 if (GET_CODE (inc_val) == CONST_INT)
6929 if (HAVE_POST_INCREMENT
6930 && (INTVAL (inc_val) == size && offset == 0))
6931 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
6933 else if (HAVE_POST_DECREMENT
6934 && (INTVAL (inc_val) == -size && offset == 0))
6935 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
6937 else if (HAVE_PRE_INCREMENT
6938 && (INTVAL (inc_val) == size && offset == size))
6939 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
6941 else if (HAVE_PRE_DECREMENT
6942 && (INTVAL (inc_val) == -size && offset == -size))
6943 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
6945 else if (HAVE_POST_MODIFY_DISP && offset == 0)
6946 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6947 gen_rtx_PLUS (Pmode,
6950 insn, x, incr, addr);
6952 else if (GET_CODE (inc_val) == REG
6953 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
6957 if (HAVE_POST_MODIFY_REG && offset == 0)
6958 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6959 gen_rtx_PLUS (Pmode,
6962 insn, x, incr, addr);
6966 #endif /* AUTO_INC_DEC */
6969 mark_used_reg (pbi, reg, cond, insn)
6970 struct propagate_block_info *pbi;
6972 rtx cond ATTRIBUTE_UNUSED;
6975 unsigned int regno_first, regno_last, i;
6976 int some_was_live, some_was_dead, some_not_set;
6978 regno_last = regno_first = REGNO (reg);
6979 if (regno_first < FIRST_PSEUDO_REGISTER)
6980 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
6982 /* Find out if any of this register is live after this instruction. */
6983 some_was_live = some_was_dead = 0;
6984 for (i = regno_first; i <= regno_last; ++i)
6986 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
6987 some_was_live |= needed_regno;
6988 some_was_dead |= ! needed_regno;
6991 /* Find out if any of the register was set this insn. */
6993 for (i = regno_first; i <= regno_last; ++i)
6994 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
6996 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6998 /* Record where each reg is used, so when the reg is set we know
6999 the next insn that uses it. */
7000 pbi->reg_next_use[regno_first] = insn;
7003 if (pbi->flags & PROP_REG_INFO)
7005 if (regno_first < FIRST_PSEUDO_REGISTER)
7007 /* If this is a register we are going to try to eliminate,
7008 don't mark it live here. If we are successful in
7009 eliminating it, it need not be live unless it is used for
7010 pseudos, in which case it will have been set live when it
7011 was allocated to the pseudos. If the register will not
7012 be eliminated, reload will set it live at that point.
7014 Otherwise, record that this function uses this register. */
7015 /* ??? The PPC backend tries to "eliminate" on the pic
7016 register to itself. This should be fixed. In the mean
7017 time, hack around it. */
7019 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
7020 && (regno_first == FRAME_POINTER_REGNUM
7021 || regno_first == ARG_POINTER_REGNUM)))
7022 for (i = regno_first; i <= regno_last; ++i)
7023 regs_ever_live[i] = 1;
7027 /* Keep track of which basic block each reg appears in. */
7029 register int blocknum = pbi->bb->index;
7030 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
7031 REG_BASIC_BLOCK (regno_first) = blocknum;
7032 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
7033 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
7035 /* Count (weighted) number of uses of each reg. */
7036 REG_FREQ (regno_first)
7037 += (optimize_size || !pbi->bb->frequency ? 1 : pbi->bb->frequency);
7038 REG_N_REFS (regno_first)++;
7042 /* Record and count the insns in which a reg dies. If it is used in
7043 this insn and was dead below the insn then it dies in this insn.
7044 If it was set in this insn, we do not make a REG_DEAD note;
7045 likewise if we already made such a note. */
7046 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
7050 /* Check for the case where the register dying partially
7051 overlaps the register set by this insn. */
7052 if (regno_first != regno_last)
7053 for (i = regno_first; i <= regno_last; ++i)
7054 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
7056 /* If none of the words in X is needed, make a REG_DEAD note.
7057 Otherwise, we must make partial REG_DEAD notes. */
7058 if (! some_was_live)
7060 if ((pbi->flags & PROP_DEATH_NOTES)
7061 && ! find_regno_note (insn, REG_DEAD, regno_first))
7063 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
7065 if (pbi->flags & PROP_REG_INFO)
7066 REG_N_DEATHS (regno_first)++;
7070 /* Don't make a REG_DEAD note for a part of a register
7071 that is set in the insn. */
7072 for (i = regno_first; i <= regno_last; ++i)
7073 if (! REGNO_REG_SET_P (pbi->reg_live, i)
7074 && ! dead_or_set_regno_p (insn, i))
7076 = alloc_EXPR_LIST (REG_DEAD,
7077 gen_rtx_REG (reg_raw_mode[i], i),
7082 /* Mark the register as being live. */
7083 for (i = regno_first; i <= regno_last; ++i)
7085 SET_REGNO_REG_SET (pbi->reg_live, i);
7087 #ifdef HAVE_conditional_execution
7088 /* If this is a conditional use, record that fact. If it is later
7089 conditionally set, we'll know to kill the register. */
7090 if (cond != NULL_RTX)
7092 splay_tree_node node;
7093 struct reg_cond_life_info *rcli;
7098 node = splay_tree_lookup (pbi->reg_cond_dead, i);
7101 /* The register was unconditionally live previously.
7102 No need to do anything. */
7106 /* The register was conditionally live previously.
7107 Subtract the new life cond from the old death cond. */
7108 rcli = (struct reg_cond_life_info *) node->value;
7109 ncond = rcli->condition;
7110 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
7112 /* If the register is now unconditionally live,
7113 remove the entry in the splay_tree. */
7114 if (ncond == const0_rtx)
7115 splay_tree_remove (pbi->reg_cond_dead, i);
7118 rcli->condition = ncond;
7119 SET_REGNO_REG_SET (pbi->reg_cond_reg,
7120 REGNO (XEXP (cond, 0)));
7126 /* The register was not previously live at all. Record
7127 the condition under which it is still dead. */
7128 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
7129 rcli->condition = not_reg_cond (cond);
7130 rcli->stores = const0_rtx;
7131 rcli->orig_condition = const0_rtx;
7132 splay_tree_insert (pbi->reg_cond_dead, i,
7133 (splay_tree_value) rcli);
7135 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
7138 else if (some_was_live)
7140 /* The register may have been conditionally live previously, but
7141 is now unconditionally live. Remove it from the conditionally
7142 dead list, so that a conditional set won't cause us to think
7144 splay_tree_remove (pbi->reg_cond_dead, i);
7150 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
7151 This is done assuming the registers needed from X are those that
7152 have 1-bits in PBI->REG_LIVE.
7154 INSN is the containing instruction. If INSN is dead, this function
7158 mark_used_regs (pbi, x, cond, insn)
7159 struct propagate_block_info *pbi;
7162 register RTX_CODE code;
7164 int flags = pbi->flags;
7167 code = GET_CODE (x);
7187 /* If we are clobbering a MEM, mark any registers inside the address
7189 if (GET_CODE (XEXP (x, 0)) == MEM)
7190 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
7194 /* Don't bother watching stores to mems if this is not the
7195 final pass. We'll not be deleting dead stores this round. */
7196 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
7198 /* Invalidate the data for the last MEM stored, but only if MEM is
7199 something that can be stored into. */
7200 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
7201 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
7202 /* Needn't clear the memory set list. */
7206 rtx temp = pbi->mem_set_list;
7207 rtx prev = NULL_RTX;
7212 next = XEXP (temp, 1);
7213 if (anti_dependence (XEXP (temp, 0), x))
7215 /* Splice temp out of the list. */
7217 XEXP (prev, 1) = next;
7219 pbi->mem_set_list = next;
7220 free_EXPR_LIST_node (temp);
7221 pbi->mem_set_list_len--;
7229 /* If the memory reference had embedded side effects (autoincrement
7230 address modes. Then we may need to kill some entries on the
7233 invalidate_mems_from_autoinc (pbi, insn);
7237 if (flags & PROP_AUTOINC)
7238 find_auto_inc (pbi, x, insn);
7243 #ifdef CLASS_CANNOT_CHANGE_MODE
7244 if (GET_CODE (SUBREG_REG (x)) == REG
7245 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
7246 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
7247 GET_MODE (SUBREG_REG (x))))
7248 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
7251 /* While we're here, optimize this case. */
7253 if (GET_CODE (x) != REG)
7258 /* See a register other than being set => mark it as needed. */
7259 mark_used_reg (pbi, x, cond, insn);
7264 register rtx testreg = SET_DEST (x);
7267 /* If storing into MEM, don't show it as being used. But do
7268 show the address as being used. */
7269 if (GET_CODE (testreg) == MEM)
7272 if (flags & PROP_AUTOINC)
7273 find_auto_inc (pbi, testreg, insn);
7275 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
7276 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7280 /* Storing in STRICT_LOW_PART is like storing in a reg
7281 in that this SET might be dead, so ignore it in TESTREG.
7282 but in some other ways it is like using the reg.
7284 Storing in a SUBREG or a bit field is like storing the entire
7285 register in that if the register's value is not used
7286 then this SET is not needed. */
7287 while (GET_CODE (testreg) == STRICT_LOW_PART
7288 || GET_CODE (testreg) == ZERO_EXTRACT
7289 || GET_CODE (testreg) == SIGN_EXTRACT
7290 || GET_CODE (testreg) == SUBREG)
7292 #ifdef CLASS_CANNOT_CHANGE_MODE
7293 if (GET_CODE (testreg) == SUBREG
7294 && GET_CODE (SUBREG_REG (testreg)) == REG
7295 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
7296 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
7297 GET_MODE (testreg)))
7298 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
7301 /* Modifying a single register in an alternate mode
7302 does not use any of the old value. But these other
7303 ways of storing in a register do use the old value. */
7304 if (GET_CODE (testreg) == SUBREG
7305 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
7310 testreg = XEXP (testreg, 0);
7313 /* If this is a store into a register or group of registers,
7314 recursively scan the value being stored. */
7316 if ((GET_CODE (testreg) == PARALLEL
7317 && GET_MODE (testreg) == BLKmode)
7318 || (GET_CODE (testreg) == REG
7319 && (regno = REGNO (testreg),
7320 ! (regno == FRAME_POINTER_REGNUM
7321 && (! reload_completed || frame_pointer_needed)))
7322 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
7323 && ! (regno == HARD_FRAME_POINTER_REGNUM
7324 && (! reload_completed || frame_pointer_needed))
7326 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
7327 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
7332 mark_used_regs (pbi, SET_DEST (x), cond, insn);
7333 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7340 case UNSPEC_VOLATILE:
7344 /* Traditional and volatile asm instructions must be considered to use
7345 and clobber all hard registers, all pseudo-registers and all of
7346 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
7348 Consider for instance a volatile asm that changes the fpu rounding
7349 mode. An insn should not be moved across this even if it only uses
7350 pseudo-regs because it might give an incorrectly rounded result.
7352 ?!? Unfortunately, marking all hard registers as live causes massive
7353 problems for the register allocator and marking all pseudos as live
7354 creates mountains of uninitialized variable warnings.
7356 So for now, just clear the memory set list and mark any regs
7357 we can find in ASM_OPERANDS as used. */
7358 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
7360 free_EXPR_LIST_list (&pbi->mem_set_list);
7361 pbi->mem_set_list_len = 0;
7364 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
7365 We can not just fall through here since then we would be confused
7366 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
7367 traditional asms unlike their normal usage. */
7368 if (code == ASM_OPERANDS)
7372 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
7373 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
7379 if (cond != NULL_RTX)
7382 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
7384 cond = COND_EXEC_TEST (x);
7385 x = COND_EXEC_CODE (x);
7389 /* We _do_not_ want to scan operands of phi nodes. Operands of
7390 a phi function are evaluated only when control reaches this
7391 block along a particular edge. Therefore, regs that appear
7392 as arguments to phi should not be added to the global live at
7400 /* Recursively scan the operands of this expression. */
7403 register const char *fmt = GET_RTX_FORMAT (code);
7406 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7410 /* Tail recursive case: save a function call level. */
7416 mark_used_regs (pbi, XEXP (x, i), cond, insn);
7418 else if (fmt[i] == 'E')
7421 for (j = 0; j < XVECLEN (x, i); j++)
7422 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
7431 try_pre_increment_1 (pbi, insn)
7432 struct propagate_block_info *pbi;
7435 /* Find the next use of this reg. If in same basic block,
7436 make it do pre-increment or pre-decrement if appropriate. */
7437 rtx x = single_set (insn);
7438 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
7439 * INTVAL (XEXP (SET_SRC (x), 1)));
7440 int regno = REGNO (SET_DEST (x));
7441 rtx y = pbi->reg_next_use[regno];
7443 && SET_DEST (x) != stack_pointer_rtx
7444 && BLOCK_NUM (y) == BLOCK_NUM (insn)
7445 /* Don't do this if the reg dies, or gets set in y; a standard addressing
7446 mode would be better. */
7447 && ! dead_or_set_p (y, SET_DEST (x))
7448 && try_pre_increment (y, SET_DEST (x), amount))
7450 /* We have found a suitable auto-increment and already changed
7451 insn Y to do it. So flush this increment instruction. */
7452 propagate_block_delete_insn (pbi->bb, insn);
7454 /* Count a reference to this reg for the increment insn we are
7455 deleting. When a reg is incremented, spilling it is worse,
7456 so we want to make that less likely. */
7457 if (regno >= FIRST_PSEUDO_REGISTER)
7459 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
7460 ? 1 : pbi->bb->frequency);
7461 REG_N_SETS (regno)++;
7464 /* Flush any remembered memories depending on the value of
7465 the incremented register. */
7466 invalidate_mems_from_set (pbi, SET_DEST (x));
7473 /* Try to change INSN so that it does pre-increment or pre-decrement
7474 addressing on register REG in order to add AMOUNT to REG.
7475 AMOUNT is negative for pre-decrement.
7476 Returns 1 if the change could be made.
7477 This checks all about the validity of the result of modifying INSN. */
7480 try_pre_increment (insn, reg, amount)
7482 HOST_WIDE_INT amount;
7486 /* Nonzero if we can try to make a pre-increment or pre-decrement.
7487 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
7489 /* Nonzero if we can try to make a post-increment or post-decrement.
7490 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
7491 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
7492 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
7495 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
7498 /* From the sign of increment, see which possibilities are conceivable
7499 on this target machine. */
7500 if (HAVE_PRE_INCREMENT && amount > 0)
7502 if (HAVE_POST_INCREMENT && amount > 0)
7505 if (HAVE_PRE_DECREMENT && amount < 0)
7507 if (HAVE_POST_DECREMENT && amount < 0)
7510 if (! (pre_ok || post_ok))
7513 /* It is not safe to add a side effect to a jump insn
7514 because if the incremented register is spilled and must be reloaded
7515 there would be no way to store the incremented value back in memory. */
7517 if (GET_CODE (insn) == JUMP_INSN)
7522 use = find_use_as_address (PATTERN (insn), reg, 0);
7523 if (post_ok && (use == 0 || use == (rtx) 1))
7525 use = find_use_as_address (PATTERN (insn), reg, -amount);
7529 if (use == 0 || use == (rtx) 1)
7532 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
7535 /* See if this combination of instruction and addressing mode exists. */
7536 if (! validate_change (insn, &XEXP (use, 0),
7537 gen_rtx_fmt_e (amount > 0
7538 ? (do_post ? POST_INC : PRE_INC)
7539 : (do_post ? POST_DEC : PRE_DEC),
7543 /* Record that this insn now has an implicit side effect on X. */
7544 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
7548 #endif /* AUTO_INC_DEC */
7550 /* Find the place in the rtx X where REG is used as a memory address.
7551 Return the MEM rtx that so uses it.
7552 If PLUSCONST is nonzero, search instead for a memory address equivalent to
7553 (plus REG (const_int PLUSCONST)).
7555 If such an address does not appear, return 0.
7556 If REG appears more than once, or is used other than in such an address,
7560 find_use_as_address (x, reg, plusconst)
7563 HOST_WIDE_INT plusconst;
7565 enum rtx_code code = GET_CODE (x);
7566 const char *fmt = GET_RTX_FORMAT (code);
7568 register rtx value = 0;
7571 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
7574 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
7575 && XEXP (XEXP (x, 0), 0) == reg
7576 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
7577 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
7580 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
7582 /* If REG occurs inside a MEM used in a bit-field reference,
7583 that is unacceptable. */
7584 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
7585 return (rtx) (HOST_WIDE_INT) 1;
7589 return (rtx) (HOST_WIDE_INT) 1;
7591 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7595 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
7599 return (rtx) (HOST_WIDE_INT) 1;
7601 else if (fmt[i] == 'E')
7604 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7606 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
7610 return (rtx) (HOST_WIDE_INT) 1;
7618 /* Write information about registers and basic blocks into FILE.
7619 This is part of making a debugging dump. */
7622 dump_regset (r, outf)
7629 fputs (" (nil)", outf);
7633 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
7635 fprintf (outf, " %d", i);
7636 if (i < FIRST_PSEUDO_REGISTER)
7637 fprintf (outf, " [%s]",
7642 /* Print a human-reaable representation of R on the standard error
7643 stream. This function is designed to be used from within the
7650 dump_regset (r, stderr);
7651 putc ('\n', stderr);
7655 dump_flow_info (file)
7659 static const char * const reg_class_names[] = REG_CLASS_NAMES;
7661 fprintf (file, "%d registers.\n", max_regno);
7662 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
7665 enum reg_class class, altclass;
7666 fprintf (file, "\nRegister %d used %d times across %d insns",
7667 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
7668 if (REG_BASIC_BLOCK (i) >= 0)
7669 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
7671 fprintf (file, "; set %d time%s", REG_N_SETS (i),
7672 (REG_N_SETS (i) == 1) ? "" : "s");
7673 if (REG_USERVAR_P (regno_reg_rtx[i]))
7674 fprintf (file, "; user var");
7675 if (REG_N_DEATHS (i) != 1)
7676 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
7677 if (REG_N_CALLS_CROSSED (i) == 1)
7678 fprintf (file, "; crosses 1 call");
7679 else if (REG_N_CALLS_CROSSED (i))
7680 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
7681 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
7682 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
7683 class = reg_preferred_class (i);
7684 altclass = reg_alternate_class (i);
7685 if (class != GENERAL_REGS || altclass != ALL_REGS)
7687 if (altclass == ALL_REGS || class == ALL_REGS)
7688 fprintf (file, "; pref %s", reg_class_names[(int) class]);
7689 else if (altclass == NO_REGS)
7690 fprintf (file, "; %s or none", reg_class_names[(int) class]);
7692 fprintf (file, "; pref %s, else %s",
7693 reg_class_names[(int) class],
7694 reg_class_names[(int) altclass]);
7696 if (REG_POINTER (regno_reg_rtx[i]))
7697 fprintf (file, "; pointer");
7698 fprintf (file, ".\n");
7701 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
7702 for (i = 0; i < n_basic_blocks; i++)
7704 register basic_block bb = BASIC_BLOCK (i);
7707 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count ",
7708 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth);
7709 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7710 fprintf (file, ", freq %i.\n", bb->frequency);
7712 fprintf (file, "Predecessors: ");
7713 for (e = bb->pred; e; e = e->pred_next)
7714 dump_edge_info (file, e, 0);
7716 fprintf (file, "\nSuccessors: ");
7717 for (e = bb->succ; e; e = e->succ_next)
7718 dump_edge_info (file, e, 1);
7720 fprintf (file, "\nRegisters live at start:");
7721 dump_regset (bb->global_live_at_start, file);
7723 fprintf (file, "\nRegisters live at end:");
7724 dump_regset (bb->global_live_at_end, file);
7735 dump_flow_info (stderr);
7739 dump_edge_info (file, e, do_succ)
7744 basic_block side = (do_succ ? e->dest : e->src);
7746 if (side == ENTRY_BLOCK_PTR)
7747 fputs (" ENTRY", file);
7748 else if (side == EXIT_BLOCK_PTR)
7749 fputs (" EXIT", file);
7751 fprintf (file, " %d", side->index);
7754 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
7758 fprintf (file, " count:");
7759 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) e->count);
7764 static const char * const bitnames[] = {
7765 "fallthru", "crit", "ab", "abcall", "eh", "fake"
7768 int i, flags = e->flags;
7772 for (i = 0; flags; i++)
7773 if (flags & (1 << i))
7779 if (i < (int) ARRAY_SIZE (bitnames))
7780 fputs (bitnames[i], file);
7782 fprintf (file, "%d", i);
7789 /* Print out one basic block with live information at start and end. */
7800 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
7801 bb->index, bb->loop_depth);
7802 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7805 fputs (";; Predecessors: ", outf);
7806 for (e = bb->pred; e; e = e->pred_next)
7807 dump_edge_info (outf, e, 0);
7810 fputs (";; Registers live at start:", outf);
7811 dump_regset (bb->global_live_at_start, outf);
7814 for (insn = bb->head, last = NEXT_INSN (bb->end);
7816 insn = NEXT_INSN (insn))
7817 print_rtl_single (outf, insn);
7819 fputs (";; Registers live at end:", outf);
7820 dump_regset (bb->global_live_at_end, outf);
7823 fputs (";; Successors: ", outf);
7824 for (e = bb->succ; e; e = e->succ_next)
7825 dump_edge_info (outf, e, 1);
7833 dump_bb (bb, stderr);
7840 dump_bb (BASIC_BLOCK (n), stderr);
7843 /* Like print_rtl, but also print out live information for the start of each
7847 print_rtl_with_bb (outf, rtx_first)
7851 register rtx tmp_rtx;
7854 fprintf (outf, "(nil)\n");
7858 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
7859 int max_uid = get_max_uid ();
7860 basic_block *start = (basic_block *)
7861 xcalloc (max_uid, sizeof (basic_block));
7862 basic_block *end = (basic_block *)
7863 xcalloc (max_uid, sizeof (basic_block));
7864 enum bb_state *in_bb_p = (enum bb_state *)
7865 xcalloc (max_uid, sizeof (enum bb_state));
7867 for (i = n_basic_blocks - 1; i >= 0; i--)
7869 basic_block bb = BASIC_BLOCK (i);
7872 start[INSN_UID (bb->head)] = bb;
7873 end[INSN_UID (bb->end)] = bb;
7874 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
7876 enum bb_state state = IN_MULTIPLE_BB;
7877 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
7879 in_bb_p[INSN_UID (x)] = state;
7886 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
7891 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
7893 fprintf (outf, ";; Start of basic block %d, registers live:",
7895 dump_regset (bb->global_live_at_start, outf);
7899 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
7900 && GET_CODE (tmp_rtx) != NOTE
7901 && GET_CODE (tmp_rtx) != BARRIER)
7902 fprintf (outf, ";; Insn is not within a basic block\n");
7903 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
7904 fprintf (outf, ";; Insn is in multiple basic blocks\n");
7906 did_output = print_rtl_single (outf, tmp_rtx);
7908 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
7910 fprintf (outf, ";; End of basic block %d, registers live:\n",
7912 dump_regset (bb->global_live_at_end, outf);
7925 if (current_function_epilogue_delay_list != 0)
7927 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
7928 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
7929 tmp_rtx = XEXP (tmp_rtx, 1))
7930 print_rtl_single (outf, XEXP (tmp_rtx, 0));
7934 /* Dump the rtl into the current debugging dump file, then abort. */
7937 print_rtl_and_abort_fcn (file, line, function)
7940 const char *function;
7944 print_rtl_with_bb (rtl_dump_file, get_insns ());
7945 fclose (rtl_dump_file);
7948 fancy_abort (file, line, function);
7951 /* Recompute register set/reference counts immediately prior to register
7954 This avoids problems with set/reference counts changing to/from values
7955 which have special meanings to the register allocators.
7957 Additionally, the reference counts are the primary component used by the
7958 register allocators to prioritize pseudos for allocation to hard regs.
7959 More accurate reference counts generally lead to better register allocation.
7961 F is the first insn to be scanned.
7963 LOOP_STEP denotes how much loop_depth should be incremented per
7964 loop nesting level in order to increase the ref count more for
7965 references in a loop.
7967 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
7968 possibly other information which is used by the register allocators. */
7971 recompute_reg_usage (f, loop_step)
7972 rtx f ATTRIBUTE_UNUSED;
7973 int loop_step ATTRIBUTE_UNUSED;
7975 allocate_reg_life_data ();
7976 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
7979 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
7980 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
7981 of the number of registers that died. */
7984 count_or_remove_death_notes (blocks, kill)
7990 for (i = n_basic_blocks - 1; i >= 0; --i)
7995 if (blocks && ! TEST_BIT (blocks, i))
7998 bb = BASIC_BLOCK (i);
8000 for (insn = bb->head;; insn = NEXT_INSN (insn))
8004 rtx *pprev = ®_NOTES (insn);
8009 switch (REG_NOTE_KIND (link))
8012 if (GET_CODE (XEXP (link, 0)) == REG)
8014 rtx reg = XEXP (link, 0);
8017 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
8020 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
8028 rtx next = XEXP (link, 1);
8029 free_EXPR_LIST_node (link);
8030 *pprev = link = next;
8036 pprev = &XEXP (link, 1);
8043 if (insn == bb->end)
8052 /* Update insns block within BB. */
8055 update_bb_for_insn (bb)
8060 if (! basic_block_for_insn)
8063 for (insn = bb->head; ; insn = NEXT_INSN (insn))
8065 set_block_for_insn (insn, bb);
8067 if (insn == bb->end)
8073 /* Record INSN's block as BB. */
8076 set_block_for_insn (insn, bb)
8080 size_t uid = INSN_UID (insn);
8081 if (uid >= basic_block_for_insn->num_elements)
8085 /* Add one-eighth the size so we don't keep calling xrealloc. */
8086 new_size = uid + (uid + 7) / 8;
8088 VARRAY_GROW (basic_block_for_insn, new_size);
8090 VARRAY_BB (basic_block_for_insn, uid) = bb;
8093 /* When a new insn has been inserted into an existing block, it will
8094 sometimes emit more than a single insn. This routine will set the
8095 block number for the specified insn, and look backwards in the insn
8096 chain to see if there are any other uninitialized insns immediately
8097 previous to this one, and set the block number for them too. */
8100 set_block_for_new_insns (insn, bb)
8104 set_block_for_insn (insn, bb);
8106 /* Scan the previous instructions setting the block number until we find
8107 an instruction that has the block number set, or we find a note
8109 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
8111 if (GET_CODE (insn) == NOTE)
8113 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
8114 || BLOCK_FOR_INSN (insn) == 0)
8115 set_block_for_insn (insn, bb);
8121 /* Verify the CFG consistency. This function check some CFG invariants and
8122 aborts when something is wrong. Hope that this function will help to
8123 convert many optimization passes to preserve CFG consistent.
8125 Currently it does following checks:
8127 - test head/end pointers
8128 - overlapping of basic blocks
8129 - edge list correctness
8130 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
8131 - tails of basic blocks (ensure that boundary is necesary)
8132 - scans body of the basic block for JUMP_INSN, CODE_LABEL
8133 and NOTE_INSN_BASIC_BLOCK
8134 - check that all insns are in the basic blocks
8135 (except the switch handling code, barriers and notes)
8136 - check that all returns are followed by barriers
8138 In future it can be extended check a lot of other stuff as well
8139 (reachability of basic blocks, life information, etc. etc.). */
8144 const int max_uid = get_max_uid ();
8145 const rtx rtx_first = get_insns ();
8146 rtx last_head = get_last_insn ();
8147 basic_block *bb_info, *last_visited;
8149 int i, last_bb_num_seen, num_bb_notes, err = 0;
8151 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
8152 last_visited = (basic_block *) xcalloc (n_basic_blocks + 2,
8153 sizeof (basic_block));
8155 for (i = n_basic_blocks - 1; i >= 0; i--)
8157 basic_block bb = BASIC_BLOCK (i);
8158 rtx head = bb->head;
8161 /* Verify the end of the basic block is in the INSN chain. */
8162 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
8167 error ("End insn %d for block %d not found in the insn stream.",
8168 INSN_UID (end), bb->index);
8172 /* Work backwards from the end to the head of the basic block
8173 to verify the head is in the RTL chain. */
8174 for (; x != NULL_RTX; x = PREV_INSN (x))
8176 /* While walking over the insn chain, verify insns appear
8177 in only one basic block and initialize the BB_INFO array
8178 used by other passes. */
8179 if (bb_info[INSN_UID (x)] != NULL)
8181 error ("Insn %d is in multiple basic blocks (%d and %d)",
8182 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
8185 bb_info[INSN_UID (x)] = bb;
8192 error ("Head insn %d for block %d not found in the insn stream.",
8193 INSN_UID (head), bb->index);
8200 /* Now check the basic blocks (boundaries etc.) */
8201 for (i = n_basic_blocks - 1; i >= 0; i--)
8203 basic_block bb = BASIC_BLOCK (i);
8204 /* Check correctness of edge lists. */
8206 int has_fallthru = 0;
8211 if (last_visited [e->dest->index + 2] == bb)
8213 error ("verify_flow_info: Duplicate edge %i->%i",
8214 e->src->index, e->dest->index);
8217 last_visited [e->dest->index + 2] = bb;
8219 if (e->flags & EDGE_FALLTHRU)
8222 if ((e->flags & EDGE_FALLTHRU)
8223 && e->src != ENTRY_BLOCK_PTR
8224 && e->dest != EXIT_BLOCK_PTR)
8227 if (e->src->index + 1 != e->dest->index)
8229 error ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
8230 e->src->index, e->dest->index);
8234 for (insn = NEXT_INSN (e->src->end); insn != e->dest->head;
8235 insn = NEXT_INSN (insn))
8236 if (GET_CODE (insn) == BARRIER || INSN_P (insn))
8238 error ("verify_flow_info: Incorrect fallthru %i->%i",
8239 e->src->index, e->dest->index);
8240 fatal_insn ("Wrong insn in the fallthru edge", insn);
8246 error ("verify_flow_info: Basic block %d succ edge is corrupted",
8248 fprintf (stderr, "Predecessor: ");
8249 dump_edge_info (stderr, e, 0);
8250 fprintf (stderr, "\nSuccessor: ");
8251 dump_edge_info (stderr, e, 1);
8252 fprintf (stderr, "\n");
8255 if (e->dest != EXIT_BLOCK_PTR)
8257 edge e2 = e->dest->pred;
8258 while (e2 && e2 != e)
8262 error ("Basic block %i edge lists are corrupted", bb->index);
8272 /* Ensure existence of barrier in BB with no fallthru edges. */
8273 for (insn = bb->end; GET_CODE (insn) != BARRIER;
8274 insn = NEXT_INSN (insn))
8276 || (GET_CODE (insn) == NOTE
8277 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
8279 error ("Missing barrier after block %i", bb->index);
8289 error ("Basic block %d pred edge is corrupted", bb->index);
8290 fputs ("Predecessor: ", stderr);
8291 dump_edge_info (stderr, e, 0);
8292 fputs ("\nSuccessor: ", stderr);
8293 dump_edge_info (stderr, e, 1);
8294 fputc ('\n', stderr);
8297 if (e->src != ENTRY_BLOCK_PTR)
8299 edge e2 = e->src->succ;
8300 while (e2 && e2 != e)
8304 error ("Basic block %i edge lists are corrupted", bb->index);
8311 /* OK pointers are correct. Now check the header of basic
8312 block. It ought to contain optional CODE_LABEL followed
8313 by NOTE_BASIC_BLOCK. */
8315 if (GET_CODE (x) == CODE_LABEL)
8319 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
8325 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
8327 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
8334 /* Do checks for empty blocks here */
8341 if (NOTE_INSN_BASIC_BLOCK_P (x))
8343 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
8344 INSN_UID (x), bb->index);
8351 if (GET_CODE (x) == JUMP_INSN
8352 || GET_CODE (x) == CODE_LABEL
8353 || GET_CODE (x) == BARRIER)
8355 error ("In basic block %d:", bb->index);
8356 fatal_insn ("Flow control insn inside a basic block", x);
8364 last_bb_num_seen = -1;
8369 if (NOTE_INSN_BASIC_BLOCK_P (x))
8371 basic_block bb = NOTE_BASIC_BLOCK (x);
8373 if (bb->index != last_bb_num_seen + 1)
8374 internal_error ("Basic blocks not numbered consecutively.");
8376 last_bb_num_seen = bb->index;
8379 if (!bb_info[INSN_UID (x)])
8381 switch (GET_CODE (x))
8388 /* An addr_vec is placed outside any block block. */
8390 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
8391 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
8392 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
8397 /* But in any case, non-deletable labels can appear anywhere. */
8401 fatal_insn ("Insn outside basic block", x);
8406 && GET_CODE (x) == JUMP_INSN
8407 && returnjump_p (x) && ! condjump_p (x)
8408 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
8409 fatal_insn ("Return not followed by barrier", x);
8414 if (num_bb_notes != n_basic_blocks)
8416 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
8417 num_bb_notes, n_basic_blocks);
8420 internal_error ("verify_flow_info failed.");
8424 free (last_visited);
8427 /* Functions to access an edge list with a vector representation.
8428 Enough data is kept such that given an index number, the
8429 pred and succ that edge represents can be determined, or
8430 given a pred and a succ, its index number can be returned.
8431 This allows algorithms which consume a lot of memory to
8432 represent the normally full matrix of edge (pred,succ) with a
8433 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
8434 wasted space in the client code due to sparse flow graphs. */
8436 /* This functions initializes the edge list. Basically the entire
8437 flowgraph is processed, and all edges are assigned a number,
8438 and the data structure is filled in. */
8443 struct edge_list *elist;
8449 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
8453 /* Determine the number of edges in the flow graph by counting successor
8454 edges on each basic block. */
8455 for (x = 0; x < n_basic_blocks; x++)
8457 basic_block bb = BASIC_BLOCK (x);
8459 for (e = bb->succ; e; e = e->succ_next)
8462 /* Don't forget successors of the entry block. */
8463 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8466 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
8467 elist->num_blocks = block_count;
8468 elist->num_edges = num_edges;
8469 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
8473 /* Follow successors of the entry block, and register these edges. */
8474 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8476 elist->index_to_edge[num_edges] = e;
8480 for (x = 0; x < n_basic_blocks; x++)
8482 basic_block bb = BASIC_BLOCK (x);
8484 /* Follow all successors of blocks, and register these edges. */
8485 for (e = bb->succ; e; e = e->succ_next)
8487 elist->index_to_edge[num_edges] = e;
8494 /* This function free's memory associated with an edge list. */
8497 free_edge_list (elist)
8498 struct edge_list *elist;
8502 free (elist->index_to_edge);
8507 /* This function provides debug output showing an edge list. */
8510 print_edge_list (f, elist)
8512 struct edge_list *elist;
8515 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
8516 elist->num_blocks - 2, elist->num_edges);
8518 for (x = 0; x < elist->num_edges; x++)
8520 fprintf (f, " %-4d - edge(", x);
8521 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
8522 fprintf (f, "entry,");
8524 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
8526 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
8527 fprintf (f, "exit)\n");
8529 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
8533 /* This function provides an internal consistency check of an edge list,
8534 verifying that all edges are present, and that there are no
8538 verify_edge_list (f, elist)
8540 struct edge_list *elist;
8542 int x, pred, succ, index;
8545 for (x = 0; x < n_basic_blocks; x++)
8547 basic_block bb = BASIC_BLOCK (x);
8549 for (e = bb->succ; e; e = e->succ_next)
8551 pred = e->src->index;
8552 succ = e->dest->index;
8553 index = EDGE_INDEX (elist, e->src, e->dest);
8554 if (index == EDGE_INDEX_NO_EDGE)
8556 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8559 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8560 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8561 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8562 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8563 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8564 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8567 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8569 pred = e->src->index;
8570 succ = e->dest->index;
8571 index = EDGE_INDEX (elist, e->src, e->dest);
8572 if (index == EDGE_INDEX_NO_EDGE)
8574 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8577 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8578 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8579 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8580 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8581 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8582 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8584 /* We've verified that all the edges are in the list, no lets make sure
8585 there are no spurious edges in the list. */
8587 for (pred = 0; pred < n_basic_blocks; pred++)
8588 for (succ = 0; succ < n_basic_blocks; succ++)
8590 basic_block p = BASIC_BLOCK (pred);
8591 basic_block s = BASIC_BLOCK (succ);
8595 for (e = p->succ; e; e = e->succ_next)
8601 for (e = s->pred; e; e = e->pred_next)
8607 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8608 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8609 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
8611 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8612 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8613 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
8614 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8615 BASIC_BLOCK (succ)));
8617 for (succ = 0; succ < n_basic_blocks; succ++)
8619 basic_block p = ENTRY_BLOCK_PTR;
8620 basic_block s = BASIC_BLOCK (succ);
8624 for (e = p->succ; e; e = e->succ_next)
8630 for (e = s->pred; e; e = e->pred_next)
8636 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8637 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8638 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
8640 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8641 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8642 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
8643 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
8644 BASIC_BLOCK (succ)));
8646 for (pred = 0; pred < n_basic_blocks; pred++)
8648 basic_block p = BASIC_BLOCK (pred);
8649 basic_block s = EXIT_BLOCK_PTR;
8653 for (e = p->succ; e; e = e->succ_next)
8659 for (e = s->pred; e; e = e->pred_next)
8665 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8666 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8667 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
8669 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8670 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8671 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
8672 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8677 /* This routine will determine what, if any, edge there is between
8678 a specified predecessor and successor. */
8681 find_edge_index (edge_list, pred, succ)
8682 struct edge_list *edge_list;
8683 basic_block pred, succ;
8686 for (x = 0; x < NUM_EDGES (edge_list); x++)
8688 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
8689 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
8692 return (EDGE_INDEX_NO_EDGE);
8695 /* This function will remove an edge from the flow graph. */
8701 edge last_pred = NULL;
8702 edge last_succ = NULL;
8704 basic_block src, dest;
8707 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
8713 last_succ->succ_next = e->succ_next;
8715 src->succ = e->succ_next;
8717 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
8723 last_pred->pred_next = e->pred_next;
8725 dest->pred = e->pred_next;
8731 /* This routine will remove any fake successor edges for a basic block.
8732 When the edge is removed, it is also removed from whatever predecessor
8736 remove_fake_successors (bb)
8740 for (e = bb->succ; e;)
8744 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
8749 /* This routine will remove all fake edges from the flow graph. If
8750 we remove all fake successors, it will automatically remove all
8751 fake predecessors. */
8754 remove_fake_edges ()
8758 for (x = 0; x < n_basic_blocks; x++)
8759 remove_fake_successors (BASIC_BLOCK (x));
8761 /* We've handled all successors except the entry block's. */
8762 remove_fake_successors (ENTRY_BLOCK_PTR);
8765 /* This function will add a fake edge between any block which has no
8766 successors, and the exit block. Some data flow equations require these
8770 add_noreturn_fake_exit_edges ()
8774 for (x = 0; x < n_basic_blocks; x++)
8775 if (BASIC_BLOCK (x)->succ == NULL)
8776 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
8779 /* This function adds a fake edge between any infinite loops to the
8780 exit block. Some optimizations require a path from each node to
8783 See also Morgan, Figure 3.10, pp. 82-83.
8785 The current implementation is ugly, not attempting to minimize the
8786 number of inserted fake edges. To reduce the number of fake edges
8787 to insert, add fake edges from _innermost_ loops containing only
8788 nodes not reachable from the exit block. */
8791 connect_infinite_loops_to_exit ()
8793 basic_block unvisited_block;
8795 /* Perform depth-first search in the reverse graph to find nodes
8796 reachable from the exit block. */
8797 struct depth_first_search_dsS dfs_ds;
8799 flow_dfs_compute_reverse_init (&dfs_ds);
8800 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
8802 /* Repeatedly add fake edges, updating the unreachable nodes. */
8805 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
8806 if (!unvisited_block)
8808 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
8809 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
8812 flow_dfs_compute_reverse_finish (&dfs_ds);
8817 /* Redirect an edge's successor from one block to another. */
8820 redirect_edge_succ (e, new_succ)
8822 basic_block new_succ;
8826 /* Disconnect the edge from the old successor block. */
8827 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
8829 *pe = (*pe)->pred_next;
8831 /* Reconnect the edge to the new successor block. */
8832 e->pred_next = new_succ->pred;
8837 /* Like previous but avoid possible dupplicate edge. */
8840 redirect_edge_succ_nodup (e, new_succ)
8842 basic_block new_succ;
8845 /* Check whether the edge is already present. */
8846 for (s = e->src->succ; s; s = s->succ_next)
8847 if (s->dest == new_succ && s != e)
8851 s->flags |= e->flags;
8852 s->probability += e->probability;
8853 s->count += e->count;
8857 redirect_edge_succ (e, new_succ);
8860 /* Redirect an edge's predecessor from one block to another. */
8863 redirect_edge_pred (e, new_pred)
8865 basic_block new_pred;
8869 /* Disconnect the edge from the old predecessor block. */
8870 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
8872 *pe = (*pe)->succ_next;
8874 /* Reconnect the edge to the new predecessor block. */
8875 e->succ_next = new_pred->succ;
8880 /* Dump the list of basic blocks in the bitmap NODES. */
8883 flow_nodes_print (str, nodes, file)
8885 const sbitmap nodes;
8893 fprintf (file, "%s { ", str);
8894 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
8895 fputs ("}\n", file);
8899 /* Dump the list of edges in the array EDGE_LIST. */
8902 flow_edge_list_print (str, edge_list, num_edges, file)
8904 const edge *edge_list;
8913 fprintf (file, "%s { ", str);
8914 for (i = 0; i < num_edges; i++)
8915 fprintf (file, "%d->%d ", edge_list[i]->src->index,
8916 edge_list[i]->dest->index);
8917 fputs ("}\n", file);
8921 /* Dump loop related CFG information. */
8924 flow_loops_cfg_dump (loops, file)
8925 const struct loops *loops;
8930 if (! loops->num || ! file || ! loops->cfg.dom)
8933 for (i = 0; i < n_basic_blocks; i++)
8937 fprintf (file, ";; %d succs { ", i);
8938 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
8939 fprintf (file, "%d ", succ->dest->index);
8940 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
8943 /* Dump the DFS node order. */
8944 if (loops->cfg.dfs_order)
8946 fputs (";; DFS order: ", file);
8947 for (i = 0; i < n_basic_blocks; i++)
8948 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
8951 /* Dump the reverse completion node order. */
8952 if (loops->cfg.rc_order)
8954 fputs (";; RC order: ", file);
8955 for (i = 0; i < n_basic_blocks; i++)
8956 fprintf (file, "%d ", loops->cfg.rc_order[i]);
8961 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
8964 flow_loop_nested_p (outer, loop)
8968 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
8972 /* Dump the loop information specified by LOOP to the stream FILE
8973 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8975 flow_loop_dump (loop, file, loop_dump_aux, verbose)
8976 const struct loop *loop;
8978 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8981 if (! loop || ! loop->header)
8984 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
8985 loop->num, INSN_UID (loop->first->head),
8986 INSN_UID (loop->last->end),
8987 loop->shared ? " shared" : "",
8988 loop->invalid ? " invalid" : "");
8989 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
8990 loop->header->index, loop->latch->index,
8991 loop->pre_header ? loop->pre_header->index : -1,
8992 loop->first->index, loop->last->index);
8993 fprintf (file, ";; depth %d, level %d, outer %ld\n",
8994 loop->depth, loop->level,
8995 (long) (loop->outer ? loop->outer->num : -1));
8997 if (loop->pre_header_edges)
8998 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
8999 loop->num_pre_header_edges, file);
9000 flow_edge_list_print (";; entry edges", loop->entry_edges,
9001 loop->num_entries, file);
9002 fprintf (file, ";; %d", loop->num_nodes);
9003 flow_nodes_print (" nodes", loop->nodes, file);
9004 flow_edge_list_print (";; exit edges", loop->exit_edges,
9005 loop->num_exits, file);
9006 if (loop->exits_doms)
9007 flow_nodes_print (";; exit doms", loop->exits_doms, file);
9009 loop_dump_aux (loop, file, verbose);
9013 /* Dump the loop information specified by LOOPS to the stream FILE,
9014 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
9016 flow_loops_dump (loops, file, loop_dump_aux, verbose)
9017 const struct loops *loops;
9019 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
9025 num_loops = loops->num;
9026 if (! num_loops || ! file)
9029 fprintf (file, ";; %d loops found, %d levels\n",
9030 num_loops, loops->levels);
9032 for (i = 0; i < num_loops; i++)
9034 struct loop *loop = &loops->array[i];
9036 flow_loop_dump (loop, file, loop_dump_aux, verbose);
9042 for (j = 0; j < i; j++)
9044 struct loop *oloop = &loops->array[j];
9046 if (loop->header == oloop->header)
9051 smaller = loop->num_nodes < oloop->num_nodes;
9053 /* If the union of LOOP and OLOOP is different than
9054 the larger of LOOP and OLOOP then LOOP and OLOOP
9055 must be disjoint. */
9056 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
9057 smaller ? oloop : loop);
9059 ";; loop header %d shared by loops %d, %d %s\n",
9060 loop->header->index, i, j,
9061 disjoint ? "disjoint" : "nested");
9068 flow_loops_cfg_dump (loops, file);
9072 /* Free all the memory allocated for LOOPS. */
9075 flow_loops_free (loops)
9076 struct loops *loops;
9085 /* Free the loop descriptors. */
9086 for (i = 0; i < loops->num; i++)
9088 struct loop *loop = &loops->array[i];
9090 if (loop->pre_header_edges)
9091 free (loop->pre_header_edges);
9093 sbitmap_free (loop->nodes);
9094 if (loop->entry_edges)
9095 free (loop->entry_edges);
9096 if (loop->exit_edges)
9097 free (loop->exit_edges);
9098 if (loop->exits_doms)
9099 sbitmap_free (loop->exits_doms);
9101 free (loops->array);
9102 loops->array = NULL;
9105 sbitmap_vector_free (loops->cfg.dom);
9106 if (loops->cfg.dfs_order)
9107 free (loops->cfg.dfs_order);
9109 if (loops->shared_headers)
9110 sbitmap_free (loops->shared_headers);
9115 /* Find the entry edges into the loop with header HEADER and nodes
9116 NODES and store in ENTRY_EDGES array. Return the number of entry
9117 edges from the loop. */
9120 flow_loop_entry_edges_find (header, nodes, entry_edges)
9122 const sbitmap nodes;
9128 *entry_edges = NULL;
9131 for (e = header->pred; e; e = e->pred_next)
9133 basic_block src = e->src;
9135 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
9142 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
9145 for (e = header->pred; e; e = e->pred_next)
9147 basic_block src = e->src;
9149 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
9150 (*entry_edges)[num_entries++] = e;
9157 /* Find the exit edges from the loop using the bitmap of loop nodes
9158 NODES and store in EXIT_EDGES array. Return the number of
9159 exit edges from the loop. */
9162 flow_loop_exit_edges_find (nodes, exit_edges)
9163 const sbitmap nodes;
9172 /* Check all nodes within the loop to see if there are any
9173 successors not in the loop. Note that a node may have multiple
9174 exiting edges ????? A node can have one jumping edge and one fallthru
9175 edge so only one of these can exit the loop. */
9177 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
9178 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
9180 basic_block dest = e->dest;
9182 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
9190 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
9192 /* Store all exiting edges into an array. */
9194 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
9195 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
9197 basic_block dest = e->dest;
9199 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
9200 (*exit_edges)[num_exits++] = e;
9208 /* Find the nodes contained within the loop with header HEADER and
9209 latch LATCH and store in NODES. Return the number of nodes within
9213 flow_loop_nodes_find (header, latch, nodes)
9222 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
9225 /* Start with only the loop header in the set of loop nodes. */
9226 sbitmap_zero (nodes);
9227 SET_BIT (nodes, header->index);
9229 header->loop_depth++;
9231 /* Push the loop latch on to the stack. */
9232 if (! TEST_BIT (nodes, latch->index))
9234 SET_BIT (nodes, latch->index);
9235 latch->loop_depth++;
9237 stack[sp++] = latch;
9246 for (e = node->pred; e; e = e->pred_next)
9248 basic_block ancestor = e->src;
9250 /* If each ancestor not marked as part of loop, add to set of
9251 loop nodes and push on to stack. */
9252 if (ancestor != ENTRY_BLOCK_PTR
9253 && ! TEST_BIT (nodes, ancestor->index))
9255 SET_BIT (nodes, ancestor->index);
9256 ancestor->loop_depth++;
9258 stack[sp++] = ancestor;
9266 /* Compute the depth first search order and store in the array
9267 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
9268 RC_ORDER is non-zero, return the reverse completion number for each
9269 node. Returns the number of nodes visited. A depth first search
9270 tries to get as far away from the starting point as quickly as
9274 flow_depth_first_order_compute (dfs_order, rc_order)
9281 int rcnum = n_basic_blocks - 1;
9284 /* Allocate stack for back-tracking up CFG. */
9285 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
9288 /* Allocate bitmap to track nodes that have been visited. */
9289 visited = sbitmap_alloc (n_basic_blocks);
9291 /* None of the nodes in the CFG have been visited yet. */
9292 sbitmap_zero (visited);
9294 /* Push the first edge on to the stack. */
9295 stack[sp++] = ENTRY_BLOCK_PTR->succ;
9303 /* Look at the edge on the top of the stack. */
9308 /* Check if the edge destination has been visited yet. */
9309 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
9311 /* Mark that we have visited the destination. */
9312 SET_BIT (visited, dest->index);
9315 dfs_order[dfsnum++] = dest->index;
9319 /* Since the DEST node has been visited for the first
9320 time, check its successors. */
9321 stack[sp++] = dest->succ;
9325 /* There are no successors for the DEST node so assign
9326 its reverse completion number. */
9328 rc_order[rcnum--] = dest->index;
9333 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
9335 /* There are no more successors for the SRC node
9336 so assign its reverse completion number. */
9338 rc_order[rcnum--] = src->index;
9342 stack[sp - 1] = e->succ_next;
9349 sbitmap_free (visited);
9351 /* The number of nodes visited should not be greater than
9353 if (dfsnum > n_basic_blocks)
9356 /* There are some nodes left in the CFG that are unreachable. */
9357 if (dfsnum < n_basic_blocks)
9362 /* Compute the depth first search order on the _reverse_ graph and
9363 store in the array DFS_ORDER, marking the nodes visited in VISITED.
9364 Returns the number of nodes visited.
9366 The computation is split into three pieces:
9368 flow_dfs_compute_reverse_init () creates the necessary data
9371 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
9372 structures. The block will start the search.
9374 flow_dfs_compute_reverse_execute () continues (or starts) the
9375 search using the block on the top of the stack, stopping when the
9378 flow_dfs_compute_reverse_finish () destroys the necessary data
9381 Thus, the user will probably call ..._init(), call ..._add_bb() to
9382 add a beginning basic block to the stack, call ..._execute(),
9383 possibly add another bb to the stack and again call ..._execute(),
9384 ..., and finally call _finish(). */
9386 /* Initialize the data structures used for depth-first search on the
9387 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
9388 added to the basic block stack. DATA is the current depth-first
9389 search context. If INITIALIZE_STACK is non-zero, there is an
9390 element on the stack. */
9393 flow_dfs_compute_reverse_init (data)
9394 depth_first_search_ds data;
9396 /* Allocate stack for back-tracking up CFG. */
9398 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
9399 * sizeof (basic_block));
9402 /* Allocate bitmap to track nodes that have been visited. */
9403 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
9405 /* None of the nodes in the CFG have been visited yet. */
9406 sbitmap_zero (data->visited_blocks);
9411 /* Add the specified basic block to the top of the dfs data
9412 structures. When the search continues, it will start at the
9416 flow_dfs_compute_reverse_add_bb (data, bb)
9417 depth_first_search_ds data;
9420 data->stack[data->sp++] = bb;
9424 /* Continue the depth-first search through the reverse graph starting
9425 with the block at the stack's top and ending when the stack is
9426 empty. Visited nodes are marked. Returns an unvisited basic
9427 block, or NULL if there is none available. */
9430 flow_dfs_compute_reverse_execute (data)
9431 depth_first_search_ds data;
9437 while (data->sp > 0)
9439 bb = data->stack[--data->sp];
9441 /* Mark that we have visited this node. */
9442 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
9444 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
9446 /* Perform depth-first search on adjacent vertices. */
9447 for (e = bb->pred; e; e = e->pred_next)
9448 flow_dfs_compute_reverse_add_bb (data, e->src);
9452 /* Determine if there are unvisited basic blocks. */
9453 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
9454 if (!TEST_BIT (data->visited_blocks, i))
9455 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
9459 /* Destroy the data structures needed for depth-first search on the
9463 flow_dfs_compute_reverse_finish (data)
9464 depth_first_search_ds data;
9467 sbitmap_free (data->visited_blocks);
9472 /* Find the root node of the loop pre-header extended basic block and
9473 the edges along the trace from the root node to the loop header. */
9476 flow_loop_pre_header_scan (loop)
9482 loop->num_pre_header_edges = 0;
9484 if (loop->num_entries != 1)
9487 ebb = loop->entry_edges[0]->src;
9489 if (ebb != ENTRY_BLOCK_PTR)
9493 /* Count number of edges along trace from loop header to
9494 root of pre-header extended basic block. Usually this is
9495 only one or two edges. */
9497 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
9499 ebb = ebb->pred->src;
9503 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
9504 loop->num_pre_header_edges = num;
9506 /* Store edges in order that they are followed. The source
9507 of the first edge is the root node of the pre-header extended
9508 basic block and the destination of the last last edge is
9510 for (e = loop->entry_edges[0]; num; e = e->src->pred)
9512 loop->pre_header_edges[--num] = e;
9518 /* Return the block for the pre-header of the loop with header
9519 HEADER where DOM specifies the dominator information. Return NULL if
9520 there is no pre-header. */
9523 flow_loop_pre_header_find (header, dom)
9527 basic_block pre_header;
9530 /* If block p is a predecessor of the header and is the only block
9531 that the header does not dominate, then it is the pre-header. */
9533 for (e = header->pred; e; e = e->pred_next)
9535 basic_block node = e->src;
9537 if (node != ENTRY_BLOCK_PTR
9538 && ! TEST_BIT (dom[node->index], header->index))
9540 if (pre_header == NULL)
9544 /* There are multiple edges into the header from outside
9545 the loop so there is no pre-header block. */
9554 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
9555 previously added. The insertion algorithm assumes that the loops
9556 are added in the order found by a depth first search of the CFG. */
9559 flow_loop_tree_node_add (prevloop, loop)
9560 struct loop *prevloop;
9564 if (flow_loop_nested_p (prevloop, loop))
9566 prevloop->inner = loop;
9567 loop->outer = prevloop;
9571 while (prevloop->outer)
9573 if (flow_loop_nested_p (prevloop->outer, loop))
9575 prevloop->next = loop;
9576 loop->outer = prevloop->outer;
9579 prevloop = prevloop->outer;
9582 prevloop->next = loop;
9586 /* Build the loop hierarchy tree for LOOPS. */
9589 flow_loops_tree_build (loops)
9590 struct loops *loops;
9595 num_loops = loops->num;
9599 /* Root the loop hierarchy tree with the first loop found.
9600 Since we used a depth first search this should be the
9602 loops->tree_root = &loops->array[0];
9603 loops->tree_root->outer = loops->tree_root->inner = loops->tree_root->next = NULL;
9605 /* Add the remaining loops to the tree. */
9606 for (i = 1; i < num_loops; i++)
9607 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
9610 /* Helper function to compute loop nesting depth and enclosed loop level
9611 for the natural loop specified by LOOP at the loop depth DEPTH.
9612 Returns the loop level. */
9615 flow_loop_level_compute (loop, depth)
9625 /* Traverse loop tree assigning depth and computing level as the
9626 maximum level of all the inner loops of this loop. The loop
9627 level is equivalent to the height of the loop in the loop tree
9628 and corresponds to the number of enclosed loop levels (including
9630 for (inner = loop->inner; inner; inner = inner->next)
9634 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
9639 loop->level = level;
9640 loop->depth = depth;
9644 /* Compute the loop nesting depth and enclosed loop level for the loop
9645 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
9649 flow_loops_level_compute (loops)
9650 struct loops *loops;
9656 /* Traverse all the outer level loops. */
9657 for (loop = loops->tree_root; loop; loop = loop->next)
9659 level = flow_loop_level_compute (loop, 1);
9667 /* Scan a single natural loop specified by LOOP collecting information
9668 about it specified by FLAGS. */
9671 flow_loop_scan (loops, loop, flags)
9672 struct loops *loops;
9676 /* Determine prerequisites. */
9677 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
9678 flags |= LOOP_EXIT_EDGES;
9680 if (flags & LOOP_ENTRY_EDGES)
9682 /* Find edges which enter the loop header.
9683 Note that the entry edges should only
9684 enter the header of a natural loop. */
9686 = flow_loop_entry_edges_find (loop->header,
9688 &loop->entry_edges);
9691 if (flags & LOOP_EXIT_EDGES)
9693 /* Find edges which exit the loop. */
9695 = flow_loop_exit_edges_find (loop->nodes,
9699 if (flags & LOOP_EXITS_DOMS)
9703 /* Determine which loop nodes dominate all the exits
9705 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
9706 sbitmap_copy (loop->exits_doms, loop->nodes);
9707 for (j = 0; j < loop->num_exits; j++)
9708 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
9709 loops->cfg.dom[loop->exit_edges[j]->src->index]);
9711 /* The header of a natural loop must dominate
9713 if (! TEST_BIT (loop->exits_doms, loop->header->index))
9717 if (flags & LOOP_PRE_HEADER)
9719 /* Look to see if the loop has a pre-header node. */
9721 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
9723 /* Find the blocks within the extended basic block of
9724 the loop pre-header. */
9725 flow_loop_pre_header_scan (loop);
9731 /* Find all the natural loops in the function and save in LOOPS structure
9732 and recalculate loop_depth information in basic block structures.
9733 FLAGS controls which loop information is collected.
9734 Return the number of natural loops found. */
9737 flow_loops_find (loops, flags)
9738 struct loops *loops;
9750 /* This function cannot be repeatedly called with different
9751 flags to build up the loop information. The loop tree
9752 must always be built if this function is called. */
9753 if (! (flags & LOOP_TREE))
9756 memset (loops, 0, sizeof (*loops));
9758 /* Taking care of this degenerate case makes the rest of
9759 this code simpler. */
9760 if (n_basic_blocks == 0)
9766 /* Compute the dominators. */
9767 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
9768 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
9770 /* Count the number of loop edges (back edges). This should be the
9771 same as the number of natural loops. */
9774 for (b = 0; b < n_basic_blocks; b++)
9778 header = BASIC_BLOCK (b);
9779 header->loop_depth = 0;
9781 for (e = header->pred; e; e = e->pred_next)
9783 basic_block latch = e->src;
9785 /* Look for back edges where a predecessor is dominated
9786 by this block. A natural loop has a single entry
9787 node (header) that dominates all the nodes in the
9788 loop. It also has single back edge to the header
9789 from a latch node. Note that multiple natural loops
9790 may share the same header. */
9791 if (b != header->index)
9794 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
9801 /* Compute depth first search order of the CFG so that outer
9802 natural loops will be found before inner natural loops. */
9803 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9804 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9805 flow_depth_first_order_compute (dfs_order, rc_order);
9807 /* Save CFG derived information to avoid recomputing it. */
9808 loops->cfg.dom = dom;
9809 loops->cfg.dfs_order = dfs_order;
9810 loops->cfg.rc_order = rc_order;
9812 /* Allocate loop structures. */
9814 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
9816 headers = sbitmap_alloc (n_basic_blocks);
9817 sbitmap_zero (headers);
9819 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
9820 sbitmap_zero (loops->shared_headers);
9822 /* Find and record information about all the natural loops
9825 for (b = 0; b < n_basic_blocks; b++)
9829 /* Search the nodes of the CFG in reverse completion order
9830 so that we can find outer loops first. */
9831 header = BASIC_BLOCK (rc_order[b]);
9833 /* Look for all the possible latch blocks for this header. */
9834 for (e = header->pred; e; e = e->pred_next)
9836 basic_block latch = e->src;
9838 /* Look for back edges where a predecessor is dominated
9839 by this block. A natural loop has a single entry
9840 node (header) that dominates all the nodes in the
9841 loop. It also has single back edge to the header
9842 from a latch node. Note that multiple natural loops
9843 may share the same header. */
9844 if (latch != ENTRY_BLOCK_PTR
9845 && TEST_BIT (dom[latch->index], header->index))
9849 loop = loops->array + num_loops;
9851 loop->header = header;
9852 loop->latch = latch;
9853 loop->num = num_loops;
9860 for (i = 0; i < num_loops; i++)
9862 struct loop *loop = &loops->array[i];
9864 /* Keep track of blocks that are loop headers so
9865 that we can tell which loops should be merged. */
9866 if (TEST_BIT (headers, loop->header->index))
9867 SET_BIT (loops->shared_headers, loop->header->index);
9868 SET_BIT (headers, loop->header->index);
9870 /* Find nodes contained within the loop. */
9871 loop->nodes = sbitmap_alloc (n_basic_blocks);
9873 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
9875 /* Compute first and last blocks within the loop.
9876 These are often the same as the loop header and
9877 loop latch respectively, but this is not always
9880 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
9882 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
9884 flow_loop_scan (loops, loop, flags);
9887 /* Natural loops with shared headers may either be disjoint or
9888 nested. Disjoint loops with shared headers cannot be inner
9889 loops and should be merged. For now just mark loops that share
9891 for (i = 0; i < num_loops; i++)
9892 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
9893 loops->array[i].shared = 1;
9895 sbitmap_free (headers);
9899 sbitmap_vector_free (dom);
9902 loops->num = num_loops;
9904 /* Build the loop hierarchy tree. */
9905 flow_loops_tree_build (loops);
9907 /* Assign the loop nesting depth and enclosed loop level for each
9909 loops->levels = flow_loops_level_compute (loops);
9915 /* Update the information regarding the loops in the CFG
9916 specified by LOOPS. */
9918 flow_loops_update (loops, flags)
9919 struct loops *loops;
9922 /* One day we may want to update the current loop data. For now
9923 throw away the old stuff and rebuild what we need. */
9925 flow_loops_free (loops);
9927 return flow_loops_find (loops, flags);
9931 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
9934 flow_loop_outside_edge_p (loop, e)
9935 const struct loop *loop;
9938 if (e->dest != loop->header)
9940 return (e->src == ENTRY_BLOCK_PTR)
9941 || ! TEST_BIT (loop->nodes, e->src->index);
9944 /* Clear LOG_LINKS fields of insns in a chain.
9945 Also clear the global_live_at_{start,end} fields of the basic block
9949 clear_log_links (insns)
9955 for (i = insns; i; i = NEXT_INSN (i))
9959 for (b = 0; b < n_basic_blocks; b++)
9961 basic_block bb = BASIC_BLOCK (b);
9963 bb->global_live_at_start = NULL;
9964 bb->global_live_at_end = NULL;
9967 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
9968 EXIT_BLOCK_PTR->global_live_at_start = NULL;
9971 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
9972 correspond to the hard registers, if any, set in that map. This
9973 could be done far more efficiently by having all sorts of special-cases
9974 with moving single words, but probably isn't worth the trouble. */
9977 reg_set_to_hard_reg_set (to, from)
9983 EXECUTE_IF_SET_IN_BITMAP
9986 if (i >= FIRST_PSEUDO_REGISTER)
9988 SET_HARD_REG_BIT (*to, i);
9992 /* Called once at intialization time. */
9997 static int initialized;
10001 gcc_obstack_init (&flow_obstack);
10002 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
10007 obstack_free (&flow_obstack, flow_firstobj);
10008 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
10012 /* Assume that the preceeding pass has possibly eliminated jump instructions
10013 or converted the unconditional jumps. Eliminate the edges from CFG. */
10016 purge_dead_edges (bb)
10020 rtx insn = bb->end;
10021 if (GET_CODE (insn) == JUMP_INSN && !simplejump_p (insn))
10023 if (GET_CODE (insn) == JUMP_INSN)
10028 /* We do care only about conditional jumps and simplejumps. */
10029 if (!any_condjump_p (insn)
10030 && !returnjump_p (insn)
10031 && !simplejump_p (insn))
10033 for (e = bb->succ; e; e = next)
10035 next = e->succ_next;
10037 /* Check purposes we can have edge. */
10038 if ((e->flags & EDGE_FALLTHRU)
10039 && any_condjump_p (insn))
10041 if (e->dest != EXIT_BLOCK_PTR
10042 && e->dest->head == JUMP_LABEL (insn))
10044 if (e->dest == EXIT_BLOCK_PTR
10045 && returnjump_p (insn))
10050 if (!bb->succ || !removed)
10053 fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
10057 /* Redistribute probabilities. */
10058 if (!bb->succ->succ_next)
10060 bb->succ->probability = REG_BR_PROB_BASE;
10061 bb->succ->count = bb->count;
10065 note = find_reg_note (insn, REG_BR_PROB, NULL);
10068 b = BRANCH_EDGE (bb);
10069 f = FALLTHRU_EDGE (bb);
10070 b->probability = INTVAL (XEXP (note, 0));
10071 f->probability = REG_BR_PROB_BASE - b->probability;
10072 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
10073 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
10077 /* If we don't see a jump insn, we don't know exactly why the block would
10078 have been broken at this point. Look for a simple, non-fallthru edge,
10079 as these are only created by conditional branches. If we find such an
10080 edge we know that there used to be a jump here and can then safely
10081 remove all non-fallthru edges. */
10082 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
10086 for (e = bb->succ; e; e = next)
10088 next = e->succ_next;
10089 if (!(e->flags & EDGE_FALLTHRU))
10092 if (!bb->succ || bb->succ->succ_next)
10094 bb->succ->probability = REG_BR_PROB_BASE;
10095 bb->succ->count = bb->count;
10098 fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n",
10103 /* Search all basic blocks for potentionally dead edges and purge them. */
10106 purge_all_dead_edges ()
10109 for (i = 0; i < n_basic_blocks; i++)
10110 purge_dead_edges (BASIC_BLOCK (i));