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));
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 *));
485 /* Find basic blocks of the current function.
486 F is the first insn of the function and NREGS the number of register
490 find_basic_blocks (f, nregs, file)
492 int nregs ATTRIBUTE_UNUSED;
493 FILE *file ATTRIBUTE_UNUSED;
496 timevar_push (TV_CFG);
498 /* Flush out existing data. */
499 if (basic_block_info != NULL)
505 /* Clear bb->aux on all extant basic blocks. We'll use this as a
506 tag for reuse during create_basic_block, just in case some pass
507 copies around basic block notes improperly. */
508 for (i = 0; i < n_basic_blocks; ++i)
509 BASIC_BLOCK (i)->aux = NULL;
511 VARRAY_FREE (basic_block_info);
514 n_basic_blocks = count_basic_blocks (f);
516 /* Size the basic block table. The actual structures will be allocated
517 by find_basic_blocks_1, since we want to keep the structure pointers
518 stable across calls to find_basic_blocks. */
519 /* ??? This whole issue would be much simpler if we called find_basic_blocks
520 exactly once, and thereafter we don't have a single long chain of
521 instructions at all until close to the end of compilation when we
522 actually lay them out. */
524 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
526 find_basic_blocks_1 (f);
528 /* Record the block to which an insn belongs. */
529 /* ??? This should be done another way, by which (perhaps) a label is
530 tagged directly with the basic block that it starts. It is used for
531 more than that currently, but IMO that is the only valid use. */
533 max_uid = get_max_uid ();
535 /* Leave space for insns life_analysis makes in some cases for auto-inc.
536 These cases are rare, so we don't need too much space. */
537 max_uid += max_uid / 10;
540 compute_bb_for_insn (max_uid);
542 /* Discover the edges of our cfg. */
543 make_edges (label_value_list, 0, n_basic_blocks - 1);
545 /* Do very simple cleanup now, for the benefit of code that runs between
546 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
547 tidy_fallthru_edges ();
549 mark_critical_edges ();
551 #ifdef ENABLE_CHECKING
554 timevar_pop (TV_CFG);
558 check_function_return_warnings ()
560 if (warn_missing_noreturn
561 && !TREE_THIS_VOLATILE (cfun->decl)
562 && EXIT_BLOCK_PTR->pred == NULL
563 && (lang_missing_noreturn_ok_p
564 && !lang_missing_noreturn_ok_p (cfun->decl)))
565 warning ("function might be possible candidate for attribute `noreturn'");
567 /* If we have a path to EXIT, then we do return. */
568 if (TREE_THIS_VOLATILE (cfun->decl)
569 && EXIT_BLOCK_PTR->pred != NULL)
570 warning ("`noreturn' function does return");
572 /* If the clobber_return_insn appears in some basic block, then we
573 do reach the end without returning a value. */
574 else if (warn_return_type
575 && cfun->x_clobber_return_insn != NULL
576 && EXIT_BLOCK_PTR->pred != NULL)
578 int max_uid = get_max_uid ();
580 /* If clobber_return_insn was excised by jump1, then renumber_insns
581 can make max_uid smaller than the number still recorded in our rtx.
582 That's fine, since this is a quick way of verifying that the insn
583 is no longer in the chain. */
584 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
586 /* Recompute insn->block mapping, since the initial mapping is
587 set before we delete unreachable blocks. */
588 compute_bb_for_insn (max_uid);
590 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
591 warning ("control reaches end of non-void function");
596 /* Count the basic blocks of the function. */
599 count_basic_blocks (f)
603 register RTX_CODE prev_code;
604 register int count = 0;
605 int saw_abnormal_edge = 0;
607 prev_code = JUMP_INSN;
608 for (insn = f; insn; insn = NEXT_INSN (insn))
610 enum rtx_code code = GET_CODE (insn);
612 if (code == CODE_LABEL
613 || (GET_RTX_CLASS (code) == 'i'
614 && (prev_code == JUMP_INSN
615 || prev_code == BARRIER
616 || saw_abnormal_edge)))
618 saw_abnormal_edge = 0;
622 /* Record whether this insn created an edge. */
623 if (code == CALL_INSN)
627 /* If there is a nonlocal goto label and the specified
628 region number isn't -1, we have an edge. */
629 if (nonlocal_goto_handler_labels
630 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
631 || INTVAL (XEXP (note, 0)) >= 0))
632 saw_abnormal_edge = 1;
634 else if (can_throw_internal (insn))
635 saw_abnormal_edge = 1;
637 else if (flag_non_call_exceptions
639 && can_throw_internal (insn))
640 saw_abnormal_edge = 1;
646 /* The rest of the compiler works a bit smoother when we don't have to
647 check for the edge case of do-nothing functions with no basic blocks. */
650 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
657 /* Scan a list of insns for labels referred to other than by jumps.
658 This is used to scan the alternatives of a call placeholder. */
660 find_label_refs (f, lvl)
666 for (insn = f; insn; insn = NEXT_INSN (insn))
667 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
671 /* Make a list of all labels referred to other than by jumps
672 (which just don't have the REG_LABEL notes).
674 Make a special exception for labels followed by an ADDR*VEC,
675 as this would be a part of the tablejump setup code.
677 Make a special exception to registers loaded with label
678 values just before jump insns that use them. */
680 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
681 if (REG_NOTE_KIND (note) == REG_LABEL)
683 rtx lab = XEXP (note, 0), next;
685 if ((next = next_nonnote_insn (lab)) != NULL
686 && GET_CODE (next) == JUMP_INSN
687 && (GET_CODE (PATTERN (next)) == ADDR_VEC
688 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
690 else if (GET_CODE (lab) == NOTE)
692 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
693 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
696 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
703 /* Assume that someone emitted code with control flow instructions to the
704 basic block. Update the data structure. */
706 find_sub_basic_blocks (bb)
711 rtx jump_insn = NULL_RTX;
715 basic_block first_bb = bb;
720 if (GET_CODE (insn) == CODE_LABEL)
721 insn = NEXT_INSN (insn);
723 /* Scan insn chain and try to find new basic block boundaries. */
726 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);
744 if (LABEL_ALTERNATE_NAME (insn))
745 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
749 /* In case we've previously split insn on the JUMP_INSN, move the
750 block header to proper place. */
753 falltru = split_block (bb, PREV_INSN (insn));
756 remove_edge (falltru);
759 /* We need some special care for those expressions. */
760 if (GET_CODE (insn) == JUMP_INSN)
762 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
763 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
773 insn = NEXT_INSN (insn);
776 /* In case we've got barrier at the end of new insn stream, put it
777 outside basic block. */
778 if (GET_CODE (bb->end) == BARRIER)
779 bb->end = PREV_INSN (bb->end);
781 /* We've possibly replaced the conditional jump by conditional jump
782 followed by cleanup at fallthru edge, so the outgoing edges may
784 purge_dead_edges (bb);
786 /* Now re-scan and wire in all edges. This expect simple (conditional)
787 jumps at the end of each new basic blocks. */
788 make_edges (NULL, first_bb->index, bb->index - 1);
791 /* Find all basic blocks of the function whose first insn is F.
793 Collect and return a list of labels whose addresses are taken. This
794 will be used in make_edges for use with computed gotos. */
797 find_basic_blocks_1 (f)
800 register rtx insn, next;
802 rtx bb_note = NULL_RTX;
808 /* We process the instructions in a slightly different way than we did
809 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
810 closed out the previous block, so that it gets attached at the proper
811 place. Since this form should be equivalent to the previous,
812 count_basic_blocks continues to use the old form as a check. */
814 for (insn = f; insn; insn = next)
816 enum rtx_code code = GET_CODE (insn);
818 next = NEXT_INSN (insn);
824 int kind = NOTE_LINE_NUMBER (insn);
826 /* Look for basic block notes with which to keep the
827 basic_block_info pointers stable. Unthread the note now;
828 we'll put it back at the right place in create_basic_block.
829 Or not at all if we've already found a note in this block. */
830 if (kind == NOTE_INSN_BASIC_BLOCK)
832 if (bb_note == NULL_RTX)
835 next = flow_delete_insn (insn);
841 /* A basic block starts at a label. If we've closed one off due
842 to a barrier or some such, no need to do it again. */
843 if (head != NULL_RTX)
845 create_basic_block (i++, head, end, bb_note);
853 /* A basic block ends at a jump. */
854 if (head == NULL_RTX)
858 /* ??? Make a special check for table jumps. The way this
859 happens is truly and amazingly gross. We are about to
860 create a basic block that contains just a code label and
861 an addr*vec jump insn. Worse, an addr_diff_vec creates
862 its own natural loop.
864 Prevent this bit of brain damage, pasting things together
865 correctly in make_edges.
867 The correct solution involves emitting the table directly
868 on the tablejump instruction as a note, or JUMP_LABEL. */
870 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
871 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
879 goto new_bb_inclusive;
882 /* A basic block ends at a barrier. It may be that an unconditional
883 jump already closed the basic block -- no need to do it again. */
884 if (head == NULL_RTX)
886 goto new_bb_exclusive;
890 /* Record whether this call created an edge. */
891 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
892 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
894 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
896 /* Scan each of the alternatives for label refs. */
897 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
898 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
899 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
900 /* Record its tail recursion label, if any. */
901 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
902 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
905 /* A basic block ends at a call that can either throw or
906 do a non-local goto. */
907 if ((nonlocal_goto_handler_labels && region >= 0)
908 || can_throw_internal (insn))
911 if (head == NULL_RTX)
916 create_basic_block (i++, head, end, bb_note);
917 head = end = NULL_RTX;
925 /* Non-call exceptions generate new blocks just like calls. */
926 if (flag_non_call_exceptions && can_throw_internal (insn))
927 goto new_bb_inclusive;
929 if (head == NULL_RTX)
938 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
942 /* Make a list of all labels referred to other than by jumps.
944 Make a special exception for labels followed by an ADDR*VEC,
945 as this would be a part of the tablejump setup code.
947 Make a special exception to registers loaded with label
948 values just before jump insns that use them. */
950 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
951 if (REG_NOTE_KIND (note) == REG_LABEL)
953 rtx lab = XEXP (note, 0), next;
955 if ((next = next_nonnote_insn (lab)) != NULL
956 && GET_CODE (next) == JUMP_INSN
957 && (GET_CODE (PATTERN (next)) == ADDR_VEC
958 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
960 else if (GET_CODE (lab) == NOTE)
962 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
963 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
966 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
971 if (head != NULL_RTX)
972 create_basic_block (i++, head, end, bb_note);
974 flow_delete_insn (bb_note);
976 if (i != n_basic_blocks)
979 label_value_list = lvl;
980 tail_recursion_label_list = trll;
983 /* Tidy the CFG by deleting unreachable code and whatnot. */
989 timevar_push (TV_CLEANUP_CFG);
990 delete_unreachable_blocks ();
991 if (try_optimize_cfg (mode))
992 delete_unreachable_blocks ();
993 mark_critical_edges ();
995 /* Kill the data we won't maintain. */
996 free_EXPR_LIST_list (&label_value_list);
997 free_EXPR_LIST_list (&tail_recursion_label_list);
998 timevar_pop (TV_CLEANUP_CFG);
1001 /* Create a new basic block consisting of the instructions between
1002 HEAD and END inclusive. Reuses the note and basic block struct
1003 in BB_NOTE, if any. */
1006 create_basic_block (index, head, end, bb_note)
1008 rtx head, end, bb_note;
1013 && ! RTX_INTEGRATED_P (bb_note)
1014 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1017 /* If we found an existing note, thread it back onto the chain. */
1021 if (GET_CODE (head) == CODE_LABEL)
1025 after = PREV_INSN (head);
1029 if (after != bb_note && NEXT_INSN (after) != bb_note)
1030 reorder_insns (bb_note, bb_note, after);
1034 /* Otherwise we must create a note and a basic block structure.
1035 Since we allow basic block structs in rtl, give the struct
1036 the same lifetime by allocating it off the function obstack
1037 rather than using malloc. */
1039 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1040 memset (bb, 0, sizeof (*bb));
1042 if (GET_CODE (head) == CODE_LABEL)
1043 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1046 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1049 NOTE_BASIC_BLOCK (bb_note) = bb;
1052 /* Always include the bb note in the block. */
1053 if (NEXT_INSN (end) == bb_note)
1059 BASIC_BLOCK (index) = bb;
1061 /* Tag the block so that we know it has been used when considering
1062 other basic block notes. */
1066 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
1067 note associated with the BLOCK. */
1070 first_insn_after_basic_block_note (block)
1075 /* Get the first instruction in the block. */
1078 if (insn == NULL_RTX)
1080 if (GET_CODE (insn) == CODE_LABEL)
1081 insn = NEXT_INSN (insn);
1082 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
1085 return NEXT_INSN (insn);
1088 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1089 indexed by INSN_UID. MAX is the size of the array. */
1092 compute_bb_for_insn (max)
1097 if (basic_block_for_insn)
1098 VARRAY_FREE (basic_block_for_insn);
1099 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1101 for (i = 0; i < n_basic_blocks; ++i)
1103 basic_block bb = BASIC_BLOCK (i);
1110 int uid = INSN_UID (insn);
1112 VARRAY_BB (basic_block_for_insn, uid) = bb;
1115 insn = NEXT_INSN (insn);
1120 /* Free the memory associated with the edge structures. */
1128 for (i = 0; i < n_basic_blocks; ++i)
1130 basic_block bb = BASIC_BLOCK (i);
1132 for (e = bb->succ; e; e = n)
1142 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1148 ENTRY_BLOCK_PTR->succ = 0;
1149 EXIT_BLOCK_PTR->pred = 0;
1154 /* Identify the edges between basic blocks MIN to MAX.
1156 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1157 that are otherwise unreachable may be reachable with a non-local goto.
1159 BB_EH_END is an array indexed by basic block number in which we record
1160 the list of exception regions active at the end of the basic block. */
1163 make_edges (label_value_list, min, max)
1164 rtx label_value_list;
1168 sbitmap *edge_cache = NULL;
1170 /* Assume no computed jump; revise as we create edges. */
1171 current_function_has_computed_jump = 0;
1173 /* Heavy use of computed goto in machine-generated code can lead to
1174 nearly fully-connected CFGs. In that case we spend a significant
1175 amount of time searching the edge lists for duplicates. */
1176 if (forced_labels || label_value_list)
1178 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1179 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1182 /* By nature of the way these get numbered, block 0 is always the entry. */
1183 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1185 for (i = min; i <= max; ++i)
1187 basic_block bb = BASIC_BLOCK (i);
1190 int force_fallthru = 0;
1192 if (GET_CODE (bb->head) == CODE_LABEL
1193 && LABEL_ALTERNATE_NAME (bb->head))
1194 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1196 /* Examine the last instruction of the block, and discover the
1197 ways we can leave the block. */
1200 code = GET_CODE (insn);
1203 if (code == JUMP_INSN)
1207 /* Recognize exception handling placeholders. */
1208 if (GET_CODE (PATTERN (insn)) == RESX)
1209 make_eh_edge (edge_cache, bb, insn);
1211 /* Recognize a non-local goto as a branch outside the
1212 current function. */
1213 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1216 /* ??? Recognize a tablejump and do the right thing. */
1217 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1218 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1219 && GET_CODE (tmp) == JUMP_INSN
1220 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1221 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1226 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1227 vec = XVEC (PATTERN (tmp), 0);
1229 vec = XVEC (PATTERN (tmp), 1);
1231 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1232 make_label_edge (edge_cache, bb,
1233 XEXP (RTVEC_ELT (vec, j), 0), 0);
1235 /* Some targets (eg, ARM) emit a conditional jump that also
1236 contains the out-of-range target. Scan for these and
1237 add an edge if necessary. */
1238 if ((tmp = single_set (insn)) != NULL
1239 && SET_DEST (tmp) == pc_rtx
1240 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1241 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1242 make_label_edge (edge_cache, bb,
1243 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1245 #ifdef CASE_DROPS_THROUGH
1246 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1247 us naturally detecting fallthru into the next block. */
1252 /* If this is a computed jump, then mark it as reaching
1253 everything on the label_value_list and forced_labels list. */
1254 else if (computed_jump_p (insn))
1256 current_function_has_computed_jump = 1;
1258 for (x = label_value_list; x; x = XEXP (x, 1))
1259 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1261 for (x = forced_labels; x; x = XEXP (x, 1))
1262 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1265 /* Returns create an exit out. */
1266 else if (returnjump_p (insn))
1267 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1269 /* Otherwise, we have a plain conditional or unconditional jump. */
1272 if (! JUMP_LABEL (insn))
1274 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1278 /* If this is a sibling call insn, then this is in effect a
1279 combined call and return, and so we need an edge to the
1280 exit block. No need to worry about EH edges, since we
1281 wouldn't have created the sibling call in the first place. */
1283 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1284 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1285 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1287 /* If this is a CALL_INSN, then mark it as reaching the active EH
1288 handler for this CALL_INSN. If we're handling non-call
1289 exceptions then any insn can reach any of the active handlers.
1291 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1293 else if (code == CALL_INSN || flag_non_call_exceptions)
1295 /* Add any appropriate EH edges. */
1296 make_eh_edge (edge_cache, bb, insn);
1298 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1300 /* ??? This could be made smarter: in some cases it's possible
1301 to tell that certain calls will not do a nonlocal goto.
1303 For example, if the nested functions that do the nonlocal
1304 gotos do not have their addresses taken, then only calls to
1305 those functions or to other nested functions that use them
1306 could possibly do nonlocal gotos. */
1307 /* We do know that a REG_EH_REGION note with a value less
1308 than 0 is guaranteed not to perform a non-local goto. */
1309 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1310 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1311 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1312 make_label_edge (edge_cache, bb, XEXP (x, 0),
1313 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1317 /* Find out if we can drop through to the next block. */
1318 insn = next_nonnote_insn (insn);
1319 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1320 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1321 else if (i + 1 < n_basic_blocks)
1323 rtx tmp = BLOCK_HEAD (i + 1);
1324 if (GET_CODE (tmp) == NOTE)
1325 tmp = next_nonnote_insn (tmp);
1326 if (force_fallthru || insn == tmp)
1327 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1332 sbitmap_vector_free (edge_cache);
1335 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1336 about the edge that is accumulated between calls. */
1339 make_edge (edge_cache, src, dst, flags)
1340 sbitmap *edge_cache;
1341 basic_block src, dst;
1347 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1348 many edges to them, and we didn't allocate memory for it. */
1349 use_edge_cache = (edge_cache
1350 && src != ENTRY_BLOCK_PTR
1351 && dst != EXIT_BLOCK_PTR);
1353 /* Make sure we don't add duplicate edges. */
1354 switch (use_edge_cache)
1357 /* Quick test for non-existance of the edge. */
1358 if (! TEST_BIT (edge_cache[src->index], dst->index))
1361 /* The edge exists; early exit if no work to do. */
1367 for (e = src->succ; e; e = e->succ_next)
1376 e = (edge) xcalloc (1, sizeof (*e));
1379 e->succ_next = src->succ;
1380 e->pred_next = dst->pred;
1389 SET_BIT (edge_cache[src->index], dst->index);
1392 /* Create an edge from a basic block to a label. */
1395 make_label_edge (edge_cache, src, label, flags)
1396 sbitmap *edge_cache;
1401 if (GET_CODE (label) != CODE_LABEL)
1404 /* If the label was never emitted, this insn is junk, but avoid a
1405 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1406 as a result of a syntax error and a diagnostic has already been
1409 if (INSN_UID (label) == 0)
1412 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1415 /* Create the edges generated by INSN in REGION. */
1418 make_eh_edge (edge_cache, src, insn)
1419 sbitmap *edge_cache;
1423 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1426 handlers = reachable_handlers (insn);
1428 for (i = handlers; i; i = XEXP (i, 1))
1429 make_label_edge (edge_cache, src, XEXP (i, 0),
1430 EDGE_ABNORMAL | EDGE_EH | is_call);
1432 free_INSN_LIST_list (&handlers);
1435 /* Identify critical edges and set the bits appropriately. */
1438 mark_critical_edges ()
1440 int i, n = n_basic_blocks;
1443 /* We begin with the entry block. This is not terribly important now,
1444 but could be if a front end (Fortran) implemented alternate entry
1446 bb = ENTRY_BLOCK_PTR;
1453 /* (1) Critical edges must have a source with multiple successors. */
1454 if (bb->succ && bb->succ->succ_next)
1456 for (e = bb->succ; e; e = e->succ_next)
1458 /* (2) Critical edges must have a destination with multiple
1459 predecessors. Note that we know there is at least one
1460 predecessor -- the edge we followed to get here. */
1461 if (e->dest->pred->pred_next)
1462 e->flags |= EDGE_CRITICAL;
1464 e->flags &= ~EDGE_CRITICAL;
1469 for (e = bb->succ; e; e = e->succ_next)
1470 e->flags &= ~EDGE_CRITICAL;
1475 bb = BASIC_BLOCK (i);
1479 /* Split a block BB after insn INSN creating a new fallthru edge.
1480 Return the new edge. Note that to keep other parts of the compiler happy,
1481 this function renumbers all the basic blocks so that the new
1482 one has a number one greater than the block split. */
1485 split_block (bb, insn)
1495 /* There is no point splitting the block after its end. */
1496 if (bb->end == insn)
1499 /* Create the new structures. */
1500 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1501 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1504 memset (new_bb, 0, sizeof (*new_bb));
1506 new_bb->head = NEXT_INSN (insn);
1507 new_bb->end = bb->end;
1510 new_bb->succ = bb->succ;
1511 bb->succ = new_edge;
1512 new_bb->pred = new_edge;
1513 new_bb->count = bb->count;
1514 new_bb->frequency = bb->frequency;
1515 new_bb->loop_depth = bb->loop_depth;
1518 new_edge->dest = new_bb;
1519 new_edge->flags = EDGE_FALLTHRU;
1520 new_edge->probability = REG_BR_PROB_BASE;
1521 new_edge->count = bb->count;
1523 /* Redirect the src of the successor edges of bb to point to new_bb. */
1524 for (e = new_bb->succ; e; e = e->succ_next)
1527 /* Place the new block just after the block being split. */
1528 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1530 /* Some parts of the compiler expect blocks to be number in
1531 sequential order so insert the new block immediately after the
1532 block being split.. */
1534 for (i = n_basic_blocks - 1; i > j + 1; --i)
1536 basic_block tmp = BASIC_BLOCK (i - 1);
1537 BASIC_BLOCK (i) = tmp;
1541 BASIC_BLOCK (i) = new_bb;
1544 if (GET_CODE (new_bb->head) == CODE_LABEL)
1546 /* Create the basic block note. */
1547 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1549 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1551 /* If the only thing in this new block was the label, make sure
1552 the block note gets included. */
1553 if (new_bb->head == new_bb->end)
1554 new_bb->end = bb_note;
1558 /* Create the basic block note. */
1559 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1561 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1562 new_bb->head = bb_note;
1565 update_bb_for_insn (new_bb);
1567 if (bb->global_live_at_start)
1569 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1570 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1571 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1573 /* We now have to calculate which registers are live at the end
1574 of the split basic block and at the start of the new basic
1575 block. Start with those registers that are known to be live
1576 at the end of the original basic block and get
1577 propagate_block to determine which registers are live. */
1578 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1579 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1580 COPY_REG_SET (bb->global_live_at_end,
1581 new_bb->global_live_at_start);
1587 /* Return label in the head of basic block. Create one if it doesn't exist. */
1592 if (block == EXIT_BLOCK_PTR)
1594 if (GET_CODE (block->head) != CODE_LABEL)
1595 block->head = emit_label_before (gen_label_rtx (), block->head);
1599 /* Return true if the block has no effect and only forwards control flow to
1600 its single destination. */
1602 forwarder_block_p (bb)
1605 rtx insn = bb->head;
1606 if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
1607 || !bb->succ || bb->succ->succ_next)
1610 while (insn != bb->end)
1612 if (active_insn_p (insn))
1614 insn = NEXT_INSN (insn);
1616 return (!active_insn_p (insn)
1617 || (GET_CODE (insn) == JUMP_INSN && onlyjump_p (insn)));
1620 /* Return nonzero if we can reach target from src by falling trought. */
1622 can_fallthru (src, target)
1623 basic_block src, target;
1625 rtx insn = src->end;
1626 rtx insn2 = target->head;
1628 if (src->index + 1 == target->index && !active_insn_p (insn2))
1629 insn2 = next_active_insn (insn2);
1630 /* ??? Later we may add code to move jump tables offline. */
1631 return next_active_insn (insn) == insn2;
1634 /* Attempt to perform edge redirection by replacing possibly complex jump
1635 instruction by unconditional jump or removing jump completely.
1636 This can apply only if all edges now point to the same block.
1638 The parameters and return values are equivalent to redirect_edge_and_branch.
1641 try_redirect_by_replacing_jump (e, target)
1645 basic_block src = e->src;
1646 rtx insn = src->end, kill_from;
1651 /* Verify that all targets will be TARGET. */
1652 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
1653 if (tmp->dest != target && tmp != e)
1655 if (tmp || !onlyjump_p (insn))
1658 /* Avoid removing branch with side effects. */
1659 set = single_set (insn);
1660 if (!set || side_effects_p (set))
1663 /* In case we zap a conditional jump, we'll need to kill
1664 the cc0 setter too. */
1667 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
1668 kill_from = PREV_INSN (insn);
1671 /* See if we can create the fallthru edge. */
1672 if (can_fallthru (src, target))
1674 src->end = PREV_INSN (kill_from);
1676 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
1679 /* Selectivly unlink whole insn chain. */
1680 flow_delete_insn_chain (kill_from, PREV_INSN (target->head));
1682 /* If this already is simplejump, redirect it. */
1683 else if (simplejump_p (insn))
1685 if (e->dest == target)
1688 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
1689 INSN_UID (insn), e->dest->index, target->index);
1690 redirect_jump (insn, block_label (target), 0);
1692 /* Or replace possibly complicated jump insn by simple jump insn. */
1695 rtx target_label = block_label (target);
1698 src->end = emit_jump_insn_before (gen_jump (target_label), kill_from);
1699 JUMP_LABEL (src->end) = target_label;
1700 LABEL_NUSES (target_label)++;
1701 if (basic_block_for_insn)
1702 set_block_for_new_insns (src->end, src);
1704 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
1705 INSN_UID (insn), INSN_UID (src->end));
1707 flow_delete_insn_chain (kill_from, insn);
1709 barrier = next_nonnote_insn (src->end);
1710 if (!barrier || GET_CODE (barrier) != BARRIER)
1711 emit_barrier_after (src->end);
1714 /* Keep only one edge out and set proper flags. */
1715 while (src->succ->succ_next)
1716 remove_edge (src->succ);
1719 e->flags = EDGE_FALLTHRU;
1722 e->probability = REG_BR_PROB_BASE;
1723 e->count = src->count;
1725 /* We don't want a block to end on a line-number note since that has
1726 the potential of changing the code between -g and not -g. */
1727 while (GET_CODE (e->src->end) == NOTE
1728 && NOTE_LINE_NUMBER (e->src->end) >= 0)
1730 rtx prev = PREV_INSN (e->src->end);
1731 flow_delete_insn (e->src->end);
1735 if (e->dest != target)
1736 redirect_edge_succ (e, target);
1740 /* Attempt to change code to redirect edge E to TARGET.
1741 Don't do that on expense of adding new instructions or reordering
1744 Function can be also called with edge destionation equivalent to the
1745 TARGET. Then it should try the simplifications and do nothing if
1748 Return true if transformation suceeded. We still return flase in case
1749 E already destinated TARGET and we didn't managed to simplify instruction
1752 redirect_edge_and_branch (e, target)
1757 rtx old_label = e->dest->head;
1758 basic_block src = e->src;
1759 rtx insn = src->end;
1761 if (e->flags & EDGE_COMPLEX)
1764 if (try_redirect_by_replacing_jump (e, target))
1766 /* Do this fast path late, as we want above code to simplify for cases
1767 where called on single edge leaving basic block containing nontrivial
1769 else if (e->dest == target)
1772 /* We can only redirect non-fallthru edges of jump insn. */
1773 if (e->flags & EDGE_FALLTHRU)
1775 if (GET_CODE (insn) != JUMP_INSN)
1778 /* Recognize a tablejump and adjust all matching cases. */
1779 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1780 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1781 && GET_CODE (tmp) == JUMP_INSN
1782 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1783 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1787 rtx new_label = block_label (target);
1789 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1790 vec = XVEC (PATTERN (tmp), 0);
1792 vec = XVEC (PATTERN (tmp), 1);
1794 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1795 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1797 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
1798 --LABEL_NUSES (old_label);
1799 ++LABEL_NUSES (new_label);
1802 /* Handle casesi dispatch insns */
1803 if ((tmp = single_set (insn)) != NULL
1804 && SET_DEST (tmp) == pc_rtx
1805 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1806 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1807 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1809 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1811 --LABEL_NUSES (old_label);
1812 ++LABEL_NUSES (new_label);
1817 /* ?? We may play the games with moving the named labels from
1818 one basic block to the other in case only one computed_jump is
1820 if (computed_jump_p (insn))
1823 /* A return instruction can't be redirected. */
1824 if (returnjump_p (insn))
1827 /* If the insn doesn't go where we think, we're confused. */
1828 if (JUMP_LABEL (insn) != old_label)
1830 redirect_jump (insn, block_label (target), 0);
1834 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
1835 e->src->index, e->dest->index, target->index);
1836 if (e->dest != target)
1839 /* Check whether the edge is already present. */
1840 for (s = src->succ; s; s=s->succ_next)
1841 if (s->dest == target)
1845 s->flags |= e->flags;
1846 s->probability += e->probability;
1847 s->count += e->count;
1851 redirect_edge_succ (e, target);
1856 /* Redirect edge even at the expense of creating new jump insn or
1857 basic block. Return new basic block if created, NULL otherwise.
1858 Abort if converison is impossible. */
1860 redirect_edge_and_branch_force (e, target)
1870 if (redirect_edge_and_branch (e, target))
1872 if (e->dest == target)
1874 if (e->flags & EDGE_ABNORMAL)
1876 if (!(e->flags & EDGE_FALLTHRU))
1879 e->flags &= ~EDGE_FALLTHRU;
1880 label = block_label (target);
1881 /* Case of the fallthru block. */
1882 if (!e->src->succ->succ_next)
1884 e->src->end = emit_jump_insn_after (gen_jump (label), e->src->end);
1885 JUMP_LABEL (e->src->end) = label;
1886 LABEL_NUSES (label)++;
1887 if (basic_block_for_insn)
1888 set_block_for_new_insns (e->src->end, e->src);
1889 emit_barrier_after (e->src->end);
1891 fprintf (rtl_dump_file,
1892 "Emitting jump insn %i to redirect edge %i->%i to %i\n",
1893 INSN_UID (e->src->end), e->src->index, e->dest->index,
1895 redirect_edge_succ (e, target);
1898 /* Redirecting fallthru edge of the conditional needs extra work. */
1901 fprintf (rtl_dump_file,
1902 "Emitting jump insn %i in new BB to redirect edge %i->%i to %i\n",
1903 INSN_UID (e->src->end), e->src->index, e->dest->index,
1906 /* Create the new structures. */
1907 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1908 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1911 memset (new_bb, 0, sizeof (*new_bb));
1913 new_bb->end = new_bb->head = e->src->end;
1914 new_bb->succ = NULL;
1915 new_bb->pred = new_edge;
1916 new_bb->count = e->count;
1917 new_bb->frequency = e->probability * e->src->frequency / REG_BR_PROB_BASE;
1918 new_bb->loop_depth = e->dest->loop_depth;
1920 new_edge->flags = EDGE_FALLTHRU;
1921 new_edge->probability = e->probability;
1922 new_edge->count = e->count;
1924 if (e->dest->global_live_at_start)
1926 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1927 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1928 COPY_REG_SET (new_bb->global_live_at_start,
1929 target->global_live_at_start);
1930 COPY_REG_SET (new_bb->global_live_at_end, new_bb->global_live_at_start);
1934 new_edge->src = e->src;
1935 new_edge->dest = new_bb;
1936 new_edge->succ_next = e->src->succ;
1937 e->src->succ = new_edge;
1938 new_edge->pred_next = NULL;
1940 /* Redirect old edge. */
1941 redirect_edge_succ (e, target);
1942 redirect_edge_pred (e, new_bb);
1943 e->probability = REG_BR_PROB_BASE;
1945 /* Place the new block just after the block being split. */
1946 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1948 /* Some parts of the compiler expect blocks to be number in
1949 sequential order so insert the new block immediately after the
1950 block being split.. */
1951 j = new_edge->src->index;
1952 for (i = n_basic_blocks - 1; i > j + 1; --i)
1954 basic_block tmp = BASIC_BLOCK (i - 1);
1955 BASIC_BLOCK (i) = tmp;
1959 BASIC_BLOCK (i) = new_bb;
1962 /* Create the basic block note. */
1963 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, new_bb->head);
1964 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1965 new_bb->head = bb_note;
1967 new_bb->end = emit_jump_insn_after (gen_jump (label), new_bb->head);
1968 JUMP_LABEL (new_bb->end) = label;
1969 LABEL_NUSES (label)++;
1970 if (basic_block_for_insn)
1971 set_block_for_new_insns (new_bb->end, new_bb);
1972 emit_barrier_after (new_bb->end);
1976 /* Split a (typically critical) edge. Return the new block.
1977 Abort on abnormal edges.
1979 ??? The code generally expects to be called on critical edges.
1980 The case of a block ending in an unconditional jump to a
1981 block with multiple predecessors is not handled optimally. */
1984 split_edge (edge_in)
1987 basic_block old_pred, bb, old_succ;
1992 /* Abnormal edges cannot be split. */
1993 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1996 old_pred = edge_in->src;
1997 old_succ = edge_in->dest;
1999 /* Create the new structures. */
2000 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
2001 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
2004 memset (bb, 0, sizeof (*bb));
2006 /* ??? This info is likely going to be out of date very soon. */
2007 if (old_succ->global_live_at_start)
2009 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2010 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2011 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
2012 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
2016 bb->succ = edge_out;
2017 bb->count = edge_in->count;
2018 bb->frequency = (edge_in->probability * edge_in->src->frequency
2019 / REG_BR_PROB_BASE);
2021 edge_in->flags &= ~EDGE_CRITICAL;
2023 edge_out->pred_next = old_succ->pred;
2024 edge_out->succ_next = NULL;
2026 edge_out->dest = old_succ;
2027 edge_out->flags = EDGE_FALLTHRU;
2028 edge_out->probability = REG_BR_PROB_BASE;
2029 edge_out->count = edge_in->count;
2031 old_succ->pred = edge_out;
2033 /* Tricky case -- if there existed a fallthru into the successor
2034 (and we're not it) we must add a new unconditional jump around
2035 the new block we're actually interested in.
2037 Further, if that edge is critical, this means a second new basic
2038 block must be created to hold it. In order to simplify correct
2039 insn placement, do this before we touch the existing basic block
2040 ordering for the block we were really wanting. */
2041 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2044 for (e = edge_out->pred_next; e; e = e->pred_next)
2045 if (e->flags & EDGE_FALLTHRU)
2050 basic_block jump_block;
2053 if ((e->flags & EDGE_CRITICAL) == 0
2054 && e->src != ENTRY_BLOCK_PTR)
2056 /* Non critical -- we can simply add a jump to the end
2057 of the existing predecessor. */
2058 jump_block = e->src;
2062 /* We need a new block to hold the jump. The simplest
2063 way to do the bulk of the work here is to recursively
2065 jump_block = split_edge (e);
2066 e = jump_block->succ;
2069 /* Now add the jump insn ... */
2070 pos = emit_jump_insn_after (gen_jump (old_succ->head),
2072 jump_block->end = pos;
2073 if (basic_block_for_insn)
2074 set_block_for_new_insns (pos, jump_block);
2075 emit_barrier_after (pos);
2077 /* ... let jump know that label is in use, ... */
2078 JUMP_LABEL (pos) = old_succ->head;
2079 ++LABEL_NUSES (old_succ->head);
2081 /* ... and clear fallthru on the outgoing edge. */
2082 e->flags &= ~EDGE_FALLTHRU;
2084 /* Continue splitting the interesting edge. */
2088 /* Place the new block just in front of the successor. */
2089 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
2090 if (old_succ == EXIT_BLOCK_PTR)
2091 j = n_basic_blocks - 1;
2093 j = old_succ->index;
2094 for (i = n_basic_blocks - 1; i > j; --i)
2096 basic_block tmp = BASIC_BLOCK (i - 1);
2097 BASIC_BLOCK (i) = tmp;
2100 BASIC_BLOCK (i) = bb;
2103 /* Create the basic block note.
2105 Where we place the note can have a noticable impact on the generated
2106 code. Consider this cfg:
2116 If we need to insert an insn on the edge from block 0 to block 1,
2117 we want to ensure the instructions we insert are outside of any
2118 loop notes that physically sit between block 0 and block 1. Otherwise
2119 we confuse the loop optimizer into thinking the loop is a phony. */
2120 if (old_succ != EXIT_BLOCK_PTR
2121 && PREV_INSN (old_succ->head)
2122 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
2123 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
2124 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
2125 PREV_INSN (old_succ->head));
2126 else if (old_succ != EXIT_BLOCK_PTR)
2127 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
2129 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
2130 NOTE_BASIC_BLOCK (bb_note) = bb;
2131 bb->head = bb->end = bb_note;
2133 /* For non-fallthry edges, we must adjust the predecessor's
2134 jump instruction to target our new block. */
2135 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
2137 if (!redirect_edge_and_branch (edge_in, bb))
2141 redirect_edge_succ (edge_in, bb);
2146 /* Queue instructions for insertion on an edge between two basic blocks.
2147 The new instructions and basic blocks (if any) will not appear in the
2148 CFG until commit_edge_insertions is called. */
2151 insert_insn_on_edge (pattern, e)
2155 /* We cannot insert instructions on an abnormal critical edge.
2156 It will be easier to find the culprit if we die now. */
2157 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
2158 == (EDGE_ABNORMAL|EDGE_CRITICAL))
2161 if (e->insns == NULL_RTX)
2164 push_to_sequence (e->insns);
2166 emit_insn (pattern);
2168 e->insns = get_insns ();
2172 /* Update the CFG for the instructions queued on edge E. */
2175 commit_one_edge_insertion (e)
2178 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
2181 /* Pull the insns off the edge now since the edge might go away. */
2183 e->insns = NULL_RTX;
2185 /* Figure out where to put these things. If the destination has
2186 one predecessor, insert there. Except for the exit block. */
2187 if (e->dest->pred->pred_next == NULL
2188 && e->dest != EXIT_BLOCK_PTR)
2192 /* Get the location correct wrt a code label, and "nice" wrt
2193 a basic block note, and before everything else. */
2195 if (GET_CODE (tmp) == CODE_LABEL)
2196 tmp = NEXT_INSN (tmp);
2197 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
2198 tmp = NEXT_INSN (tmp);
2199 if (tmp == bb->head)
2202 after = PREV_INSN (tmp);
2205 /* If the source has one successor and the edge is not abnormal,
2206 insert there. Except for the entry block. */
2207 else if ((e->flags & EDGE_ABNORMAL) == 0
2208 && e->src->succ->succ_next == NULL
2209 && e->src != ENTRY_BLOCK_PTR)
2212 /* It is possible to have a non-simple jump here. Consider a target
2213 where some forms of unconditional jumps clobber a register. This
2214 happens on the fr30 for example.
2216 We know this block has a single successor, so we can just emit
2217 the queued insns before the jump. */
2218 if (GET_CODE (bb->end) == JUMP_INSN)
2224 /* We'd better be fallthru, or we've lost track of what's what. */
2225 if ((e->flags & EDGE_FALLTHRU) == 0)
2232 /* Otherwise we must split the edge. */
2235 bb = split_edge (e);
2239 /* Now that we've found the spot, do the insertion. */
2241 /* Set the new block number for these insns, if structure is allocated. */
2242 if (basic_block_for_insn)
2245 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
2246 set_block_for_insn (i, bb);
2251 emit_insns_before (insns, before);
2252 if (before == bb->head)
2255 last = prev_nonnote_insn (before);
2259 last = emit_insns_after (insns, after);
2260 if (after == bb->end)
2264 if (returnjump_p (last))
2266 /* ??? Remove all outgoing edges from BB and add one for EXIT.
2267 This is not currently a problem because this only happens
2268 for the (single) epilogue, which already has a fallthru edge
2272 if (e->dest != EXIT_BLOCK_PTR
2273 || e->succ_next != NULL
2274 || (e->flags & EDGE_FALLTHRU) == 0)
2276 e->flags &= ~EDGE_FALLTHRU;
2278 emit_barrier_after (last);
2282 flow_delete_insn (before);
2284 else if (GET_CODE (last) == JUMP_INSN)
2286 find_sub_basic_blocks (bb);
2289 /* Update the CFG for all queued instructions. */
2292 commit_edge_insertions ()
2297 #ifdef ENABLE_CHECKING
2298 verify_flow_info ();
2302 bb = ENTRY_BLOCK_PTR;
2307 for (e = bb->succ; e; e = next)
2309 next = e->succ_next;
2311 commit_one_edge_insertion (e);
2314 if (++i >= n_basic_blocks)
2316 bb = BASIC_BLOCK (i);
2320 /* Add fake edges to the function exit for any non constant calls in
2321 the bitmap of blocks specified by BLOCKS or to the whole CFG if
2322 BLOCKS is zero. Return the nuber of blocks that were split. */
2325 flow_call_edges_add (blocks)
2329 int blocks_split = 0;
2333 /* Map bb indicies into basic block pointers since split_block
2334 will renumber the basic blocks. */
2336 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2340 for (i = 0; i < n_basic_blocks; i++)
2341 bbs[bb_num++] = BASIC_BLOCK (i);
2345 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2347 bbs[bb_num++] = BASIC_BLOCK (i);
2352 /* Now add fake edges to the function exit for any non constant
2353 calls since there is no way that we can determine if they will
2356 for (i = 0; i < bb_num; i++)
2358 basic_block bb = bbs[i];
2362 for (insn = bb->end; ; insn = prev_insn)
2364 prev_insn = PREV_INSN (insn);
2365 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2369 /* Note that the following may create a new basic block
2370 and renumber the existing basic blocks. */
2371 e = split_block (bb, insn);
2375 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2377 if (insn == bb->head)
2383 verify_flow_info ();
2386 return blocks_split;
2389 /* Find unreachable blocks. An unreachable block will have NULL in
2390 block->aux, a non-NULL value indicates the block is reachable. */
2393 find_unreachable_blocks ()
2397 basic_block *tos, *worklist;
2400 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2402 /* Use basic_block->aux as a marker. Clear them all. */
2404 for (i = 0; i < n; ++i)
2405 BASIC_BLOCK (i)->aux = NULL;
2407 /* Add our starting points to the worklist. Almost always there will
2408 be only one. It isn't inconcievable that we might one day directly
2409 support Fortran alternate entry points. */
2411 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2415 /* Mark the block with a handy non-null value. */
2419 /* Iterate: find everything reachable from what we've already seen. */
2421 while (tos != worklist)
2423 basic_block b = *--tos;
2425 for (e = b->succ; e; e = e->succ_next)
2436 /* Delete all unreachable basic blocks. */
2438 delete_unreachable_blocks ()
2442 find_unreachable_blocks ();
2444 /* Delete all unreachable basic blocks. Count down so that we
2445 don't interfere with the block renumbering that happens in
2446 flow_delete_block. */
2448 for (i = n_basic_blocks - 1; i >= 0; --i)
2450 basic_block b = BASIC_BLOCK (i);
2453 /* This block was found. Tidy up the mark. */
2456 flow_delete_block (b);
2459 tidy_fallthru_edges ();
2462 /* Return true if NOTE is not one of the ones that must be kept paired,
2463 so that we may simply delete them. */
2466 can_delete_note_p (note)
2469 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2470 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2473 /* Unlink a chain of insns between START and FINISH, leaving notes
2474 that must be paired. */
2477 flow_delete_insn_chain (start, finish)
2480 /* Unchain the insns one by one. It would be quicker to delete all
2481 of these with a single unchaining, rather than one at a time, but
2482 we need to keep the NOTE's. */
2488 next = NEXT_INSN (start);
2489 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2491 else if (GET_CODE (start) == CODE_LABEL
2492 && ! can_delete_label_p (start))
2494 const char *name = LABEL_NAME (start);
2495 PUT_CODE (start, NOTE);
2496 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2497 NOTE_SOURCE_FILE (start) = name;
2500 next = flow_delete_insn (start);
2502 if (start == finish)
2508 /* Delete the insns in a (non-live) block. We physically delete every
2509 non-deleted-note insn, and update the flow graph appropriately.
2511 Return nonzero if we deleted an exception handler. */
2513 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2514 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2517 flow_delete_block (b)
2520 int deleted_handler = 0;
2523 /* If the head of this block is a CODE_LABEL, then it might be the
2524 label for an exception handler which can't be reached.
2526 We need to remove the label from the exception_handler_label list
2527 and remove the associated NOTE_INSN_EH_REGION_BEG and
2528 NOTE_INSN_EH_REGION_END notes. */
2532 never_reached_warning (insn);
2534 if (GET_CODE (insn) == CODE_LABEL)
2535 maybe_remove_eh_handler (insn);
2537 /* Include any jump table following the basic block. */
2539 if (GET_CODE (end) == JUMP_INSN
2540 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2541 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2542 && GET_CODE (tmp) == JUMP_INSN
2543 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2544 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2547 /* Include any barrier that may follow the basic block. */
2548 tmp = next_nonnote_insn (end);
2549 if (tmp && GET_CODE (tmp) == BARRIER)
2552 /* Selectively delete the entire chain. */
2553 flow_delete_insn_chain (insn, end);
2555 /* Remove the edges into and out of this block. Note that there may
2556 indeed be edges in, if we are removing an unreachable loop. */
2560 for (e = b->pred; e; e = next)
2562 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2565 next = e->pred_next;
2569 for (e = b->succ; e; e = next)
2571 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2574 next = e->succ_next;
2583 /* Remove the basic block from the array, and compact behind it. */
2586 return deleted_handler;
2589 /* Remove block B from the basic block array and compact behind it. */
2595 int i, n = n_basic_blocks;
2597 for (i = b->index; i + 1 < n; ++i)
2599 basic_block x = BASIC_BLOCK (i + 1);
2600 BASIC_BLOCK (i) = x;
2604 basic_block_info->num_elements--;
2608 /* Delete INSN by patching it out. Return the next insn. */
2611 flow_delete_insn (insn)
2614 rtx prev = PREV_INSN (insn);
2615 rtx next = NEXT_INSN (insn);
2618 PREV_INSN (insn) = NULL_RTX;
2619 NEXT_INSN (insn) = NULL_RTX;
2620 INSN_DELETED_P (insn) = 1;
2623 NEXT_INSN (prev) = next;
2625 PREV_INSN (next) = prev;
2627 set_last_insn (prev);
2629 if (GET_CODE (insn) == CODE_LABEL)
2630 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2632 /* If deleting a jump, decrement the use count of the label. Deleting
2633 the label itself should happen in the normal course of block merging. */
2634 if (GET_CODE (insn) == JUMP_INSN
2635 && JUMP_LABEL (insn)
2636 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2637 LABEL_NUSES (JUMP_LABEL (insn))--;
2639 /* Also if deleting an insn that references a label. */
2640 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2641 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2642 LABEL_NUSES (XEXP (note, 0))--;
2644 if (GET_CODE (insn) == JUMP_INSN
2645 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
2646 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
2648 rtx pat = PATTERN (insn);
2649 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
2650 int len = XVECLEN (pat, diff_vec_p);
2653 for (i = 0; i < len; i++)
2654 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
2660 /* True if a given label can be deleted. */
2663 can_delete_label_p (label)
2668 if (LABEL_PRESERVE_P (label))
2671 for (x = forced_labels; x; x = XEXP (x, 1))
2672 if (label == XEXP (x, 0))
2674 for (x = label_value_list; x; x = XEXP (x, 1))
2675 if (label == XEXP (x, 0))
2677 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2678 if (label == XEXP (x, 0))
2681 /* User declared labels must be preserved. */
2682 if (LABEL_NAME (label) != 0)
2689 tail_recursion_label_p (label)
2694 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2695 if (label == XEXP (x, 0))
2701 /* Blocks A and B are to be merged into a single block A. The insns
2702 are already contiguous, hence `nomove'. */
2705 merge_blocks_nomove (a, b)
2709 rtx b_head, b_end, a_end;
2710 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2713 /* If there was a CODE_LABEL beginning B, delete it. */
2716 if (GET_CODE (b_head) == CODE_LABEL)
2718 /* Detect basic blocks with nothing but a label. This can happen
2719 in particular at the end of a function. */
2720 if (b_head == b_end)
2722 del_first = del_last = b_head;
2723 b_head = NEXT_INSN (b_head);
2726 /* Delete the basic block note. */
2727 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2729 if (b_head == b_end)
2734 b_head = NEXT_INSN (b_head);
2737 /* If there was a jump out of A, delete it. */
2739 if (GET_CODE (a_end) == JUMP_INSN)
2743 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2744 if (GET_CODE (prev) != NOTE
2745 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2752 /* If this was a conditional jump, we need to also delete
2753 the insn that set cc0. */
2754 if (prev && sets_cc0_p (prev))
2757 prev = prev_nonnote_insn (prev);
2766 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2767 del_first = NEXT_INSN (a_end);
2769 /* Delete everything marked above as well as crap that might be
2770 hanging out between the two blocks. */
2771 flow_delete_insn_chain (del_first, del_last);
2773 /* Normally there should only be one successor of A and that is B, but
2774 partway though the merge of blocks for conditional_execution we'll
2775 be merging a TEST block with THEN and ELSE successors. Free the
2776 whole lot of them and hope the caller knows what they're doing. */
2778 remove_edge (a->succ);
2780 /* Adjust the edges out of B for the new owner. */
2781 for (e = b->succ; e; e = e->succ_next)
2785 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2786 b->pred = b->succ = NULL;
2788 /* Reassociate the insns of B with A. */
2791 if (basic_block_for_insn)
2793 BLOCK_FOR_INSN (b_head) = a;
2794 while (b_head != b_end)
2796 b_head = NEXT_INSN (b_head);
2797 BLOCK_FOR_INSN (b_head) = a;
2807 /* Blocks A and B are to be merged into a single block. A has no incoming
2808 fallthru edge, so it can be moved before B without adding or modifying
2809 any jumps (aside from the jump from A to B). */
2812 merge_blocks_move_predecessor_nojumps (a, b)
2815 rtx start, end, barrier;
2821 barrier = next_nonnote_insn (end);
2822 if (GET_CODE (barrier) != BARRIER)
2824 flow_delete_insn (barrier);
2826 /* Move block and loop notes out of the chain so that we do not
2827 disturb their order.
2829 ??? A better solution would be to squeeze out all the non-nested notes
2830 and adjust the block trees appropriately. Even better would be to have
2831 a tighter connection between block trees and rtl so that this is not
2833 start = squeeze_notes (start, end);
2835 /* Scramble the insn chain. */
2836 if (end != PREV_INSN (b->head))
2837 reorder_insns (start, end, PREV_INSN (b->head));
2841 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2842 a->index, b->index);
2845 /* Swap the records for the two blocks around. Although we are deleting B,
2846 A is now where B was and we want to compact the BB array from where
2848 BASIC_BLOCK (a->index) = b;
2849 BASIC_BLOCK (b->index) = a;
2851 a->index = b->index;
2854 /* Now blocks A and B are contiguous. Merge them. */
2855 merge_blocks_nomove (a, b);
2860 /* Blocks A and B are to be merged into a single block. B has no outgoing
2861 fallthru edge, so it can be moved after A without adding or modifying
2862 any jumps (aside from the jump from A to B). */
2865 merge_blocks_move_successor_nojumps (a, b)
2868 rtx start, end, barrier;
2872 barrier = NEXT_INSN (end);
2874 /* Recognize a jump table following block B. */
2876 && GET_CODE (barrier) == CODE_LABEL
2877 && NEXT_INSN (barrier)
2878 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2879 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2880 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2882 end = NEXT_INSN (barrier);
2883 barrier = NEXT_INSN (end);
2886 /* There had better have been a barrier there. Delete it. */
2887 if (barrier && GET_CODE (barrier) == BARRIER)
2888 flow_delete_insn (barrier);
2890 /* Move block and loop notes out of the chain so that we do not
2891 disturb their order.
2893 ??? A better solution would be to squeeze out all the non-nested notes
2894 and adjust the block trees appropriately. Even better would be to have
2895 a tighter connection between block trees and rtl so that this is not
2897 start = squeeze_notes (start, end);
2899 /* Scramble the insn chain. */
2900 reorder_insns (start, end, a->end);
2902 /* Now blocks A and B are contiguous. Merge them. */
2903 merge_blocks_nomove (a, b);
2907 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2908 b->index, a->index);
2914 /* Attempt to merge basic blocks that are potentially non-adjacent.
2915 Return true iff the attempt succeeded. */
2918 merge_blocks (e, b, c, mode)
2923 /* If C has a tail recursion label, do not merge. There is no
2924 edge recorded from the call_placeholder back to this label, as
2925 that would make optimize_sibling_and_tail_recursive_calls more
2926 complex for no gain. */
2927 if (GET_CODE (c->head) == CODE_LABEL
2928 && tail_recursion_label_p (c->head))
2931 /* If B has a fallthru edge to C, no need to move anything. */
2932 if (e->flags & EDGE_FALLTHRU)
2934 merge_blocks_nomove (b, c);
2938 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2939 b->index, c->index);
2944 /* Otherwise we will need to move code around. Do that only if expensive
2945 transformations are allowed. */
2946 else if (mode & CLEANUP_EXPENSIVE)
2948 edge tmp_edge, c_fallthru_edge;
2949 int c_has_outgoing_fallthru;
2950 int b_has_incoming_fallthru;
2952 /* Avoid overactive code motion, as the forwarder blocks should be
2953 eliminated by edge redirection instead. One exception might have
2954 been if B is a forwarder block and C has no fallthru edge, but
2955 that should be cleaned up by bb-reorder instead. */
2956 if (forwarder_block_p (b) || forwarder_block_p (c))
2959 /* We must make sure to not munge nesting of lexical blocks,
2960 and loop notes. This is done by squeezing out all the notes
2961 and leaving them there to lie. Not ideal, but functional. */
2963 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2964 if (tmp_edge->flags & EDGE_FALLTHRU)
2966 c_has_outgoing_fallthru = (tmp_edge != NULL);
2967 c_fallthru_edge = tmp_edge;
2969 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2970 if (tmp_edge->flags & EDGE_FALLTHRU)
2972 b_has_incoming_fallthru = (tmp_edge != NULL);
2974 /* If B does not have an incoming fallthru, then it can be moved
2975 immediately before C without introducing or modifying jumps.
2976 C cannot be the first block, so we do not have to worry about
2977 accessing a non-existent block. */
2978 if (! b_has_incoming_fallthru)
2979 return merge_blocks_move_predecessor_nojumps (b, c);
2981 /* Otherwise, we're going to try to move C after B. If C does
2982 not have an outgoing fallthru, then it can be moved
2983 immediately after B without introducing or modifying jumps. */
2984 if (! c_has_outgoing_fallthru)
2985 return merge_blocks_move_successor_nojumps (b, c);
2987 /* Otherwise, we'll need to insert an extra jump, and possibly
2988 a new block to contain it. We can't redirect to EXIT_BLOCK_PTR,
2989 as we don't have explicit return instructions before epilogues
2990 are generated, so give up on that case. */
2992 if (c_fallthru_edge->dest != EXIT_BLOCK_PTR
2993 && merge_blocks_move_successor_nojumps (b, c))
2995 basic_block target = c_fallthru_edge->dest;
2999 /* This is a dirty hack to avoid code duplication.
3001 Set edge to point to wrong basic block, so
3002 redirect_edge_and_branch_force will do the trick
3003 and rewire edge back to the original location. */
3004 redirect_edge_succ (c_fallthru_edge, ENTRY_BLOCK_PTR);
3005 new = redirect_edge_and_branch_force (c_fallthru_edge, target);
3007 /* We've just created barrier, but another barrier is
3008 already present in the stream. Avoid the duplicate. */
3009 barrier = next_nonnote_insn (new ? new->end : b->end);
3010 if (GET_CODE (barrier) != BARRIER)
3012 flow_delete_insn (barrier);
3020 /* Simplify a conditional jump around an unconditional jump.
3021 Return true if something changed. */
3024 try_simplify_condjump (cbranch_block)
3025 basic_block cbranch_block;
3027 basic_block jump_block, jump_dest_block, cbranch_dest_block;
3028 edge cbranch_jump_edge, cbranch_fallthru_edge;
3031 /* Verify that there are exactly two successors. */
3032 if (!cbranch_block->succ
3033 || !cbranch_block->succ->succ_next
3034 || cbranch_block->succ->succ_next->succ_next)
3037 /* Verify that we've got a normal conditional branch at the end
3039 cbranch_insn = cbranch_block->end;
3040 if (!any_condjump_p (cbranch_insn))
3043 cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block);
3044 cbranch_jump_edge = BRANCH_EDGE (cbranch_block);
3046 /* The next block must not have multiple predecessors, must not
3047 be the last block in the function, and must contain just the
3048 unconditional jump. */
3049 jump_block = cbranch_fallthru_edge->dest;
3050 if (jump_block->pred->pred_next
3051 || jump_block->index == n_basic_blocks - 1
3052 || !forwarder_block_p (jump_block))
3054 jump_dest_block = jump_block->succ->dest;
3056 /* The conditional branch must target the block after the
3057 unconditional branch. */
3058 cbranch_dest_block = cbranch_jump_edge->dest;
3060 if (!can_fallthru (jump_block, cbranch_dest_block))
3063 /* Invert the conditional branch. Prevent jump.c from deleting
3064 "unreachable" instructions. */
3065 LABEL_NUSES (JUMP_LABEL (cbranch_insn))++;
3066 if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 1))
3068 LABEL_NUSES (JUMP_LABEL (cbranch_insn))--;
3073 fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n",
3074 INSN_UID (cbranch_insn), INSN_UID (jump_block->end));
3076 /* Success. Update the CFG to match. */
3077 redirect_edge_succ (cbranch_jump_edge, cbranch_dest_block);
3078 redirect_edge_succ (cbranch_fallthru_edge, jump_dest_block);
3079 cbranch_jump_edge->flags |= EDGE_FALLTHRU;
3080 cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
3082 flow_delete_block (jump_block);
3083 /* Selectively unlink the sequence. */
3084 if (cbranch_jump_edge->src->end != PREV_INSN (cbranch_jump_edge->dest->head))
3085 flow_delete_insn_chain (NEXT_INSN (cbranch_jump_edge->src->end),
3086 PREV_INSN (cbranch_jump_edge->dest->head));
3090 /* Attempt to forward edges leaving basic block B.
3091 Return true if sucessful. */
3094 try_forward_edges (b)
3097 bool changed = false;
3100 for (e = b->succ; e ; e = next)
3102 basic_block target, first;
3105 next = e->succ_next;
3107 /* Skip complex edges because we don't know how to update them.
3108 Skip fallthru edges because there's no jump to update. */
3109 if (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3112 target = first = e->dest;
3115 /* Look for the real destination of the jump.
3116 Avoid inifinite loop in the infinite empty loop by counting
3117 up to n_basic_blocks. */
3118 while (forwarder_block_p (target)
3119 && target->succ->dest != EXIT_BLOCK_PTR
3120 && counter < n_basic_blocks)
3122 /* Bypass trivial infinite loops. */
3123 if (target == target->succ->dest)
3124 counter = n_basic_blocks;
3125 target = target->succ->dest, counter++;
3128 if (counter >= n_basic_blocks)
3131 fprintf (rtl_dump_file, "Infinite loop in BB %i.\n",
3134 else if (target == first)
3135 ; /* We didn't do anything. */
3136 else if (redirect_edge_and_branch (e, target))
3138 /* We successfully forwarded the edge. Now update profile
3139 data: for each edge we traversed in the chain, remove
3140 the original edge's execution count. */
3143 first->count -= e->count;
3144 first->succ->count -= e->count;
3145 first->frequency -= ((e->probability * b->frequency
3146 + REG_BR_PROB_BASE / 2)
3147 / REG_BR_PROB_BASE);
3148 first = first->succ->dest;
3150 while (first != target);
3157 fprintf (rtl_dump_file, "Forwarding edge %i->%i to %i failed.\n",
3158 b->index, e->dest->index, target->index);
3165 /* Look through the insns at the end of BB1 and BB2 and find the longest
3166 sequence that are equivalent. Store the first insns for that sequence
3167 in *F1 and *F2 and return the sequence length.
3169 To simplify callers of this function, if the blocks match exactly,
3170 store the head of the blocks in *F1 and *F2. */
3173 flow_find_cross_jump (mode, bb1, bb2, f1, f2)
3174 int mode ATTRIBUTE_UNUSED;
3175 basic_block bb1, bb2;
3178 rtx i1, i2, p1, p2, last1, last2, afterlast1, afterlast2;
3181 /* Skip simple jumps at the end of the blocks. Complex jumps still
3182 need to be compared for equivalence, which we'll do below. */
3185 if (onlyjump_p (i1))
3186 i1 = PREV_INSN (i1);
3188 if (onlyjump_p (i2))
3189 i2 = PREV_INSN (i2);
3191 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
3195 while ((GET_CODE (i1) == NOTE && i1 != bb1->head))
3196 i1 = PREV_INSN (i1);
3197 while ((GET_CODE (i2) == NOTE && i2 != bb2->head))
3198 i2 = PREV_INSN (i2);
3200 if (i1 == bb1->head || i2 == bb2->head)
3203 /* Verify that I1 and I2 are equivalent. */
3205 if (GET_CODE (i1) != GET_CODE (i2))
3211 /* If this is a CALL_INSN, compare register usage information.
3212 If we don't check this on stack register machines, the two
3213 CALL_INSNs might be merged leaving reg-stack.c with mismatching
3214 numbers of stack registers in the same basic block.
3215 If we don't check this on machines with delay slots, a delay slot may
3216 be filled that clobbers a parameter expected by the subroutine.
3218 ??? We take the simple route for now and assume that if they're
3219 equal, they were constructed identically. */
3221 if (GET_CODE (i1) == CALL_INSN
3222 && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
3223 CALL_INSN_FUNCTION_USAGE (i2)))
3227 /* If cross_jump_death_matters is not 0, the insn's mode
3228 indicates whether or not the insn contains any stack-like
3231 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
3233 /* If register stack conversion has already been done, then
3234 death notes must also be compared before it is certain that
3235 the two instruction streams match. */
3238 HARD_REG_SET i1_regset, i2_regset;
3240 CLEAR_HARD_REG_SET (i1_regset);
3241 CLEAR_HARD_REG_SET (i2_regset);
3243 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
3244 if (REG_NOTE_KIND (note) == REG_DEAD
3245 && STACK_REG_P (XEXP (note, 0)))
3246 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
3248 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
3249 if (REG_NOTE_KIND (note) == REG_DEAD
3250 && STACK_REG_P (XEXP (note, 0)))
3251 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
3253 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
3262 if (GET_CODE (p1) != GET_CODE (p2))
3265 if (! rtx_renumbered_equal_p (p1, p2))
3267 /* The following code helps take care of G++ cleanups. */
3268 rtx equiv1 = find_reg_equal_equiv_note (i1);
3269 rtx equiv2 = find_reg_equal_equiv_note (i2);
3271 if (equiv1 && equiv2
3272 /* If the equivalences are not to a constant, they may
3273 reference pseudos that no longer exist, so we can't
3275 && CONSTANT_P (XEXP (equiv1, 0))
3276 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
3278 rtx s1 = single_set (i1);
3279 rtx s2 = single_set (i2);
3280 if (s1 != 0 && s2 != 0
3281 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
3283 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
3284 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
3285 if (! rtx_renumbered_equal_p (p1, p2))
3287 else if (apply_change_group ())
3295 /* Don't begin a cross-jump with a USE or CLOBBER insn. */
3296 if (GET_CODE (p1) != USE && GET_CODE (p1) != CLOBBER)
3298 afterlast1 = last1, afterlast2 = last2;
3299 last1 = i1, last2 = i2;
3302 i1 = PREV_INSN (i1);
3303 i2 = PREV_INSN (i2);
3309 /* Don't allow the insn after a compare to be shared by
3310 cross-jumping unless the compare is also shared. */
3311 if (reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1))
3312 last1 = afterlast1, last2 = afterlast2, ninsns--;
3316 /* Include preceeding notes and labels in the cross-jump. One,
3317 this may bring us to the head of the blocks as requested above.
3318 Two, it keeps line number notes as matched as may be. */
3321 while (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == NOTE)
3322 last1 = PREV_INSN (last1);
3323 if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL)
3324 last1 = PREV_INSN (last1);
3325 while (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == NOTE)
3326 last2 = PREV_INSN (last2);
3327 if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL)
3328 last2 = PREV_INSN (last2);
3337 /* Return true iff outgoing edges of BB1 and BB2 match, together with
3338 the branch instruction. This means that if we commonize the control
3339 flow before end of the basic block, the semantic remains unchanged.
3341 We may assume that there exists one edge with a common destination. */
3344 outgoing_edges_match (bb1, bb2)
3348 /* If BB1 has only one successor, we must be looking at an unconditional
3349 jump. Which, by the assumption above, means that we only need to check
3350 that BB2 has one successor. */
3351 if (bb1->succ && !bb1->succ->succ_next)
3352 return (bb2->succ && !bb2->succ->succ_next);
3354 /* Match conditional jumps - this may get tricky when fallthru and branch
3355 edges are crossed. */
3357 && bb1->succ->succ_next
3358 && !bb1->succ->succ_next->succ_next
3359 && any_condjump_p (bb1->end))
3361 edge b1, f1, b2, f2;
3362 bool reverse, match;
3363 rtx set1, set2, cond1, cond2;
3364 enum rtx_code code1, code2;
3367 || !bb2->succ->succ_next
3368 || bb1->succ->succ_next->succ_next
3369 || !any_condjump_p (bb2->end))
3372 b1 = BRANCH_EDGE (bb1);
3373 b2 = BRANCH_EDGE (bb2);
3374 f1 = FALLTHRU_EDGE (bb1);
3375 f2 = FALLTHRU_EDGE (bb2);
3377 /* Get around possible forwarders on fallthru edges. Other cases
3378 should be optimized out already. */
3379 if (forwarder_block_p (f1->dest))
3380 f1 = f1->dest->succ;
3381 if (forwarder_block_p (f2->dest))
3382 f2 = f2->dest->succ;
3384 /* To simplify use of this function, return false if there are
3385 unneeded forwarder blocks. These will get eliminated later
3386 during cleanup_cfg. */
3387 if (forwarder_block_p (f1->dest)
3388 || forwarder_block_p (f2->dest)
3389 || forwarder_block_p (b1->dest)
3390 || forwarder_block_p (b2->dest))
3393 if (f1->dest == f2->dest && b1->dest == b2->dest)
3395 else if (f1->dest == b2->dest && b1->dest == f2->dest)
3400 set1 = pc_set (bb1->end);
3401 set2 = pc_set (bb2->end);
3402 if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
3403 != (XEXP (SET_SRC (set2), 1) == pc_rtx))
3406 cond1 = XEXP (SET_SRC (set1), 0);
3407 cond2 = XEXP (SET_SRC (set2), 0);
3408 code1 = GET_CODE (cond1);
3410 code2 = reversed_comparison_code (cond2, bb2->end);
3412 code2 = GET_CODE (cond2);
3413 if (code2 == UNKNOWN)
3416 /* Verify codes and operands match. */
3417 match = ((code1 == code2
3418 && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
3419 && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
3420 || (code1 == swap_condition (code2)
3421 && rtx_renumbered_equal_p (XEXP (cond1, 1),
3423 && rtx_renumbered_equal_p (XEXP (cond1, 0),
3426 /* If we return true, we will join the blocks. Which means that
3427 we will only have one branch prediction bit to work with. Thus
3428 we require the existing branches to have probabilities that are
3430 /* ??? We should use bb->frequency to allow merging in infrequently
3431 executed blocks, but at the moment it is not available when
3432 cleanup_cfg is run. */
3433 if (match && !optimize_size)
3437 note1 = find_reg_note (bb1->end, REG_BR_PROB, 0);
3438 note2 = find_reg_note (bb2->end, REG_BR_PROB, 0);
3442 prob1 = INTVAL (XEXP (note1, 0));
3443 prob2 = INTVAL (XEXP (note2, 0));
3445 prob2 = REG_BR_PROB_BASE - prob2;
3447 /* Fail if the difference in probabilities is
3449 if (abs (prob1 - prob2) > REG_BR_PROB_BASE / 20)
3452 else if (note1 || note2)
3456 if (rtl_dump_file && match)
3457 fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n",
3458 bb1->index, bb2->index);
3463 /* ??? We can handle computed jumps too. This may be important for
3464 inlined functions containing switch statements. Also jumps w/o
3465 fallthru edges can be handled by simply matching whole insn. */
3469 /* E1 and E2 are edges with the same destination block. Search their
3470 predecessors for common code. If found, redirect control flow from
3471 (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */
3474 try_crossjump_to_edge (mode, e1, e2)
3479 basic_block src1 = e1->src, src2 = e2->src;
3480 basic_block redirect_to;
3481 rtx newpos1, newpos2;
3486 /* Search backward through forwarder blocks. We don't need to worry
3487 about multiple entry or chained forwarders, as they will be optimized
3488 away. We do this to look past the unconditional jump following a
3489 conditional jump that is required due to the current CFG shape. */
3491 && !src1->pred->pred_next
3492 && forwarder_block_p (src1))
3498 && !src2->pred->pred_next
3499 && forwarder_block_p (src2))
3505 /* Nothing to do if we reach ENTRY, or a common source block. */
3506 if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR)
3511 /* Seeing more than 1 forwarder blocks would confuse us later... */
3512 if (forwarder_block_p (e1->dest)
3513 && forwarder_block_p (e1->dest->succ->dest))
3515 if (forwarder_block_p (e2->dest)
3516 && forwarder_block_p (e2->dest->succ->dest))
3519 /* Likewise with dead code. */
3520 /* ??? Won't we have eliminated these by now? */
3521 if (!src1->pred || !src2->pred)
3524 /* Likewise with non-jump edges. */
3525 /* ??? Non-jump? You mean GET_CODE (e1->src-end) != JUMP_INSN?
3526 This fails for computed-goto as well, which may in fact be joinable. */
3527 if (e1->flags & EDGE_COMPLEX)
3530 /* Look for the common insn sequence, part the first ... */
3531 if (!outgoing_edges_match (src1, src2))
3534 /* ... and part the second. */
3535 nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2);
3539 /* Avoid splitting if possible. */
3540 if (newpos2 == src2->head)
3545 fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n",
3546 src2->index, nmatch);
3547 redirect_to = split_block (src2, PREV_INSN (newpos2))->dest;
3551 fprintf (rtl_dump_file,
3552 "Cross jumping from bb %i to bb %i; %i common insns\n",
3553 src1->index, src2->index, nmatch);
3555 redirect_to->count += src1->count;
3556 redirect_to->frequency += src1->frequency;
3558 /* Recompute the frequencies and counts of outgoing edges. */
3559 for (s = redirect_to->succ; s; s = s->succ_next)
3562 basic_block d = s->dest;
3564 if (forwarder_block_p (d))
3566 for (s2 = src1->succ; ; s2 = s2->succ_next)
3568 basic_block d2 = s2->dest;
3569 if (forwarder_block_p (d2))
3570 d2 = d2->succ->dest;
3574 s->count += s2->count;
3576 /* Take care to update possible forwarder blocks. We verified
3577 that there is no more than one in the chain, so we can't run
3578 into infinite loop. */
3579 if (forwarder_block_p (s->dest))
3581 s->dest->succ->count += s2->count;
3582 s->dest->count += s2->count;
3583 s->dest->frequency += ((s->probability * s->src->frequency)
3584 / REG_BR_PROB_BASE);
3586 if (forwarder_block_p (s2->dest))
3588 s2->dest->succ->count -= s2->count;
3589 s2->dest->count -= s2->count;
3590 s2->dest->frequency -= ((s->probability * s->src->frequency)
3591 / REG_BR_PROB_BASE);
3593 if (!redirect_to->frequency && !src1->frequency)
3594 s->probability = (s->probability + s2->probability) / 2;
3597 ((s->probability * redirect_to->frequency +
3598 s2->probability * src1->frequency)
3599 / (redirect_to->frequency + src1->frequency));
3602 /* FIXME: enable once probabilities are fetched properly at CFG build. */
3604 note = find_reg_note (redirect_to->end, REG_BR_PROB, 0);
3606 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (redirect_to)->probability);
3609 /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */
3611 /* Skip possible basic block header. */
3612 if (GET_CODE (newpos1) == CODE_LABEL)
3613 newpos1 = NEXT_INSN (newpos1);
3614 if (GET_CODE (newpos1) == NOTE)
3615 newpos1 = NEXT_INSN (newpos1);
3618 /* Emit the jump insn. */
3619 label = block_label (redirect_to);
3620 src1->end = emit_jump_insn_before (gen_jump (label), newpos1);
3621 JUMP_LABEL (src1->end) = label;
3622 LABEL_NUSES (label)++;
3623 if (basic_block_for_insn)
3624 set_block_for_new_insns (src1->end, src1);
3626 /* Delete the now unreachable instructions. */
3627 flow_delete_insn_chain (newpos1, last);
3629 /* Make sure there is a barrier after the new jump. */
3630 last = next_nonnote_insn (src1->end);
3631 if (!last || GET_CODE (last) != BARRIER)
3632 emit_barrier_after (src1->end);
3636 remove_edge (src1->succ);
3637 make_edge (NULL, src1, redirect_to, 0);
3642 /* Search the predecessors of BB for common insn sequences. When found,
3643 share code between them by redirecting control flow. Return true if
3644 any changes made. */
3647 try_crossjump_bb (mode, bb)
3651 edge e, e2, nexte2, nexte, fallthru;
3654 /* Nothing to do if there is not at least two incomming edges. */
3655 if (!bb->pred || !bb->pred->pred_next)
3658 /* It is always cheapest to redirect a block that ends in a branch to
3659 a block that falls through into BB, as that adds no branches to the
3660 program. We'll try that combination first. */
3661 for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next)
3662 if (fallthru->flags & EDGE_FALLTHRU)
3666 for (e = bb->pred; e; e = nexte)
3668 nexte = e->pred_next;
3670 /* Elide complex edges now, as neither try_crossjump_to_edge
3671 nor outgoing_edges_match can handle them. */
3672 if (e->flags & EDGE_COMPLEX)
3675 /* As noted above, first try with the fallthru predecessor. */
3678 /* Don't combine the fallthru edge into anything else.
3679 If there is a match, we'll do it the other way around. */
3683 if (try_crossjump_to_edge (mode, e, fallthru))
3691 /* Non-obvious work limiting check: Recognize that we're going
3692 to call try_crossjump_bb on every basic block. So if we have
3693 two blocks with lots of outgoing edges (a switch) and they
3694 share lots of common destinations, then we would do the
3695 cross-jump check once for each common destination.
3697 Now, if the blocks actually are cross-jump candidates, then
3698 all of their destinations will be shared. Which means that
3699 we only need check them for cross-jump candidacy once. We
3700 can eliminate redundant checks of crossjump(A,B) by arbitrarily
3701 choosing to do the check from the block for which the edge
3702 in question is the first successor of A. */
3703 if (e->src->succ != e)
3706 for (e2 = bb->pred; e2; e2 = nexte2)
3708 nexte2 = e2->pred_next;
3713 /* We've already checked the fallthru edge above. */
3717 /* Again, neither try_crossjump_to_edge nor outgoing_edges_match
3718 can handle complex edges. */
3719 if (e2->flags & EDGE_COMPLEX)
3722 /* The "first successor" check above only prevents multiple
3723 checks of crossjump(A,B). In order to prevent redundant
3724 checks of crossjump(B,A), require that A be the block
3725 with the lowest index. */
3726 /* ??? Perhaps better is lowest execution frequency. */
3727 if (e->src->index > e2->src->index)
3730 if (try_crossjump_to_edge (mode, e, e2))
3742 /* Do simple CFG optimizations - basic block merging, simplifying of jump
3743 instructions etc. Return nonzero if changes were made. */
3746 try_optimize_cfg (mode)
3750 bool changed_overall = false;
3754 /* Attempt to merge blocks as made possible by edge removal. If a block
3755 has only one successor, and the successor has only one predecessor,
3756 they may be combined. */
3764 fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n",
3767 for (i = 0; i < n_basic_blocks;)
3769 basic_block c, b = BASIC_BLOCK (i);
3771 bool changed_here = false;
3773 /* Delete trivially dead basic blocks. */
3774 while (b->pred == NULL)
3776 c = BASIC_BLOCK (b->index - 1);
3778 fprintf (rtl_dump_file, "Deleting block %i.\n", b->index);
3779 flow_delete_block (b);
3784 /* Remove code labels no longer used. Don't do this before
3785 CALL_PLACEHOLDER is removed, as some branches may be hidden
3787 if (b->pred->pred_next == NULL
3788 && (b->pred->flags & EDGE_FALLTHRU)
3789 && !(b->pred->flags & EDGE_COMPLEX)
3790 && GET_CODE (b->head) == CODE_LABEL
3791 && (!(mode & CLEANUP_PRE_SIBCALL)
3792 || !tail_recursion_label_p (b->head))
3793 /* If previous block ends with condjump jumping to next BB,
3794 we can't delete the label. */
3795 && (b->pred->src == ENTRY_BLOCK_PTR
3796 || !reg_mentioned_p (b->head, b->pred->src->end)))
3798 rtx label = b->head;
3799 b->head = NEXT_INSN (b->head);
3800 flow_delete_insn_chain (label, label);
3802 fprintf (rtl_dump_file, "Deleted label in block %i.\n",
3806 /* If we fall through an empty block, we can remove it. */
3807 if (b->pred->pred_next == NULL
3808 && (b->pred->flags & EDGE_FALLTHRU)
3809 && GET_CODE (b->head) != CODE_LABEL
3810 && forwarder_block_p (b)
3811 /* Note that forwarder_block_p true ensures that there
3812 is a successor for this block. */
3813 && (b->succ->flags & EDGE_FALLTHRU)
3814 && n_basic_blocks > 1)
3817 fprintf (rtl_dump_file, "Deleting fallthru block %i.\n",
3819 c = BASIC_BLOCK (b->index ? b->index - 1 : 1);
3820 redirect_edge_succ (b->pred, b->succ->dest);
3821 flow_delete_block (b);
3826 /* Merge blocks. Loop because chains of blocks might be
3828 while ((s = b->succ) != NULL
3829 && s->succ_next == NULL
3830 && !(s->flags & EDGE_COMPLEX)
3831 && (c = s->dest) != EXIT_BLOCK_PTR
3832 && c->pred->pred_next == NULL
3833 /* If the jump insn has side effects,
3834 we can't kill the edge. */
3835 && (GET_CODE (b->end) != JUMP_INSN
3836 || onlyjump_p (b->end))
3837 && merge_blocks (s, b, c, mode))
3838 changed_here = true;
3840 /* Simplify branch over branch. */
3841 if ((mode & CLEANUP_EXPENSIVE) && try_simplify_condjump (b))
3842 changed_here = true;
3844 /* If B has a single outgoing edge, but uses a non-trivial jump
3845 instruction without side-effects, we can either delete the
3846 jump entirely, or replace it with a simple unconditional jump.
3847 Use redirect_edge_and_branch to do the dirty work. */
3849 && ! b->succ->succ_next
3850 && b->succ->dest != EXIT_BLOCK_PTR
3851 && onlyjump_p (b->end)
3852 && redirect_edge_and_branch (b->succ, b->succ->dest))
3853 changed_here = true;
3855 /* Simplify branch to branch. */
3856 if (try_forward_edges (b))
3857 changed_here = true;
3859 /* Look for shared code between blocks. */
3860 if ((mode & CLEANUP_CROSSJUMP)
3861 && try_crossjump_bb (mode, b))
3862 changed_here = true;
3864 /* Don't get confused by the index shift caused by deleting
3872 if ((mode & CLEANUP_CROSSJUMP)
3873 && try_crossjump_bb (mode, EXIT_BLOCK_PTR))
3876 #ifdef ENABLE_CHECKING
3878 verify_flow_info ();
3881 changed_overall |= changed;
3884 return changed_overall;
3887 /* The given edge should potentially be a fallthru edge. If that is in
3888 fact true, delete the jump and barriers that are in the way. */
3891 tidy_fallthru_edge (e, b, c)
3897 /* ??? In a late-running flow pass, other folks may have deleted basic
3898 blocks by nopping out blocks, leaving multiple BARRIERs between here
3899 and the target label. They ought to be chastized and fixed.
3901 We can also wind up with a sequence of undeletable labels between
3902 one block and the next.
3904 So search through a sequence of barriers, labels, and notes for
3905 the head of block C and assert that we really do fall through. */
3907 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
3910 /* Remove what will soon cease being the jump insn from the source block.
3911 If block B consisted only of this single jump, turn it into a deleted
3914 if (GET_CODE (q) == JUMP_INSN
3916 && (any_uncondjump_p (q)
3917 || (b->succ == e && e->succ_next == NULL)))
3920 /* If this was a conditional jump, we need to also delete
3921 the insn that set cc0. */
3922 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
3929 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
3930 NOTE_SOURCE_FILE (q) = 0;
3936 /* We don't want a block to end on a line-number note since that has
3937 the potential of changing the code between -g and not -g. */
3938 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
3945 /* Selectively unlink the sequence. */
3946 if (q != PREV_INSN (c->head))
3947 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
3949 e->flags |= EDGE_FALLTHRU;
3952 /* Fix up edges that now fall through, or rather should now fall through
3953 but previously required a jump around now deleted blocks. Simplify
3954 the search by only examining blocks numerically adjacent, since this
3955 is how find_basic_blocks created them. */
3958 tidy_fallthru_edges ()
3962 for (i = 1; i < n_basic_blocks; ++i)
3964 basic_block b = BASIC_BLOCK (i - 1);
3965 basic_block c = BASIC_BLOCK (i);
3968 /* We care about simple conditional or unconditional jumps with
3971 If we had a conditional branch to the next instruction when
3972 find_basic_blocks was called, then there will only be one
3973 out edge for the block which ended with the conditional
3974 branch (since we do not create duplicate edges).
3976 Furthermore, the edge will be marked as a fallthru because we
3977 merge the flags for the duplicate edges. So we do not want to
3978 check that the edge is not a FALLTHRU edge. */
3979 if ((s = b->succ) != NULL
3980 && ! (s->flags & EDGE_COMPLEX)
3981 && s->succ_next == NULL
3983 /* If the jump insn has side effects, we can't tidy the edge. */
3984 && (GET_CODE (b->end) != JUMP_INSN
3985 || onlyjump_p (b->end)))
3986 tidy_fallthru_edge (s, b, c);
3990 /* Perform data flow analysis.
3991 F is the first insn of the function; FLAGS is a set of PROP_* flags
3992 to be used in accumulating flow info. */
3995 life_analysis (f, file, flags)
4000 #ifdef ELIMINABLE_REGS
4002 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
4005 /* Record which registers will be eliminated. We use this in
4008 CLEAR_HARD_REG_SET (elim_reg_set);
4010 #ifdef ELIMINABLE_REGS
4011 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
4012 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
4014 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
4018 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
4020 /* The post-reload life analysis have (on a global basis) the same
4021 registers live as was computed by reload itself. elimination
4022 Otherwise offsets and such may be incorrect.
4024 Reload will make some registers as live even though they do not
4027 We don't want to create new auto-incs after reload, since they
4028 are unlikely to be useful and can cause problems with shared
4030 if (reload_completed)
4031 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
4033 /* We want alias analysis information for local dead store elimination. */
4034 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4035 init_alias_analysis ();
4037 /* Always remove no-op moves. Do this before other processing so
4038 that we don't have to keep re-scanning them. */
4039 delete_noop_moves (f);
4041 /* Some targets can emit simpler epilogues if they know that sp was
4042 not ever modified during the function. After reload, of course,
4043 we've already emitted the epilogue so there's no sense searching. */
4044 if (! reload_completed)
4045 notice_stack_pointer_modification (f);
4047 /* Allocate and zero out data structures that will record the
4048 data from lifetime analysis. */
4049 allocate_reg_life_data ();
4050 allocate_bb_life_data ();
4052 /* Find the set of registers live on function exit. */
4053 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
4055 /* "Update" life info from zero. It'd be nice to begin the
4056 relaxation with just the exit and noreturn blocks, but that set
4057 is not immediately handy. */
4059 if (flags & PROP_REG_INFO)
4060 memset (regs_ever_live, 0, sizeof (regs_ever_live));
4061 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
4064 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4065 end_alias_analysis ();
4068 dump_flow_info (file);
4070 free_basic_block_vars (1);
4072 #ifdef ENABLE_CHECKING
4076 /* Search for any REG_LABEL notes which reference deleted labels. */
4077 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4079 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4081 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
4088 /* A subroutine of verify_wide_reg, called through for_each_rtx.
4089 Search for REGNO. If found, abort if it is not wider than word_mode. */
4092 verify_wide_reg_1 (px, pregno)
4097 unsigned int regno = *(int *) pregno;
4099 if (GET_CODE (x) == REG && REGNO (x) == regno)
4101 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
4108 /* A subroutine of verify_local_live_at_start. Search through insns
4109 between HEAD and END looking for register REGNO. */
4112 verify_wide_reg (regno, head, end)
4119 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
4123 head = NEXT_INSN (head);
4126 /* We didn't find the register at all. Something's way screwy. */
4128 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
4129 print_rtl_and_abort ();
4132 /* A subroutine of update_life_info. Verify that there are no untoward
4133 changes in live_at_start during a local update. */
4136 verify_local_live_at_start (new_live_at_start, bb)
4137 regset new_live_at_start;
4140 if (reload_completed)
4142 /* After reload, there are no pseudos, nor subregs of multi-word
4143 registers. The regsets should exactly match. */
4144 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
4148 fprintf (rtl_dump_file,
4149 "live_at_start mismatch in bb %d, aborting\n",
4151 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
4152 debug_bitmap_file (rtl_dump_file, new_live_at_start);
4154 print_rtl_and_abort ();
4161 /* Find the set of changed registers. */
4162 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
4164 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
4166 /* No registers should die. */
4167 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
4170 fprintf (rtl_dump_file,
4171 "Register %d died unexpectedly in block %d\n", i,
4173 print_rtl_and_abort ();
4176 /* Verify that the now-live register is wider than word_mode. */
4177 verify_wide_reg (i, bb->head, bb->end);
4182 /* Updates life information starting with the basic blocks set in BLOCKS.
4183 If BLOCKS is null, consider it to be the universal set.
4185 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
4186 we are only expecting local modifications to basic blocks. If we find
4187 extra registers live at the beginning of a block, then we either killed
4188 useful data, or we have a broken split that wants data not provided.
4189 If we find registers removed from live_at_start, that means we have
4190 a broken peephole that is killing a register it shouldn't.
4192 ??? This is not true in one situation -- when a pre-reload splitter
4193 generates subregs of a multi-word pseudo, current life analysis will
4194 lose the kill. So we _can_ have a pseudo go live. How irritating.
4196 Including PROP_REG_INFO does not properly refresh regs_ever_live
4197 unless the caller resets it to zero. */
4200 update_life_info (blocks, extent, prop_flags)
4202 enum update_life_extent extent;
4206 regset_head tmp_head;
4209 tmp = INITIALIZE_REG_SET (tmp_head);
4211 /* For a global update, we go through the relaxation process again. */
4212 if (extent != UPDATE_LIFE_LOCAL)
4214 calculate_global_regs_live (blocks, blocks,
4215 prop_flags & PROP_SCAN_DEAD_CODE);
4217 /* If asked, remove notes from the blocks we'll update. */
4218 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
4219 count_or_remove_death_notes (blocks, 1);
4224 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4226 basic_block bb = BASIC_BLOCK (i);
4228 COPY_REG_SET (tmp, bb->global_live_at_end);
4229 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4231 if (extent == UPDATE_LIFE_LOCAL)
4232 verify_local_live_at_start (tmp, bb);
4237 for (i = n_basic_blocks - 1; i >= 0; --i)
4239 basic_block bb = BASIC_BLOCK (i);
4241 COPY_REG_SET (tmp, bb->global_live_at_end);
4242 propagate_block (bb, tmp, NULL, NULL, prop_flags);
4244 if (extent == UPDATE_LIFE_LOCAL)
4245 verify_local_live_at_start (tmp, bb);
4251 if (prop_flags & PROP_REG_INFO)
4253 /* The only pseudos that are live at the beginning of the function
4254 are those that were not set anywhere in the function. local-alloc
4255 doesn't know how to handle these correctly, so mark them as not
4256 local to any one basic block. */
4257 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
4258 FIRST_PSEUDO_REGISTER, i,
4259 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4261 /* We have a problem with any pseudoreg that lives across the setjmp.
4262 ANSI says that if a user variable does not change in value between
4263 the setjmp and the longjmp, then the longjmp preserves it. This
4264 includes longjmp from a place where the pseudo appears dead.
4265 (In principle, the value still exists if it is in scope.)
4266 If the pseudo goes in a hard reg, some other value may occupy
4267 that hard reg where this pseudo is dead, thus clobbering the pseudo.
4268 Conclusion: such a pseudo must not go in a hard reg. */
4269 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
4270 FIRST_PSEUDO_REGISTER, i,
4272 if (regno_reg_rtx[i] != 0)
4274 REG_LIVE_LENGTH (i) = -1;
4275 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4281 /* Free the variables allocated by find_basic_blocks.
4283 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
4286 free_basic_block_vars (keep_head_end_p)
4287 int keep_head_end_p;
4289 if (basic_block_for_insn)
4291 VARRAY_FREE (basic_block_for_insn);
4292 basic_block_for_insn = NULL;
4295 if (! keep_head_end_p)
4297 if (basic_block_info)
4300 VARRAY_FREE (basic_block_info);
4304 ENTRY_BLOCK_PTR->aux = NULL;
4305 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
4306 EXIT_BLOCK_PTR->aux = NULL;
4307 EXIT_BLOCK_PTR->global_live_at_start = NULL;
4311 /* Delete any insns that copy a register to itself. */
4314 delete_noop_moves (f)
4315 rtx f ATTRIBUTE_UNUSED;
4321 for (i = 0; i < n_basic_blocks; i++)
4323 bb = BASIC_BLOCK (i);
4324 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
4326 next = NEXT_INSN (insn);
4327 if (INSN_P (insn) && noop_move_p (insn))
4329 if (insn == bb->end)
4330 bb->end = PREV_INSN (insn);
4331 flow_delete_insn (insn);
4337 /* Determine if the stack pointer is constant over the life of the function.
4338 Only useful before prologues have been emitted. */
4341 notice_stack_pointer_modification_1 (x, pat, data)
4343 rtx pat ATTRIBUTE_UNUSED;
4344 void *data ATTRIBUTE_UNUSED;
4346 if (x == stack_pointer_rtx
4347 /* The stack pointer is only modified indirectly as the result
4348 of a push until later in flow. See the comments in rtl.texi
4349 regarding Embedded Side-Effects on Addresses. */
4350 || (GET_CODE (x) == MEM
4351 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
4352 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
4353 current_function_sp_is_unchanging = 0;
4357 notice_stack_pointer_modification (f)
4362 /* Assume that the stack pointer is unchanging if alloca hasn't
4364 current_function_sp_is_unchanging = !current_function_calls_alloca;
4365 if (! current_function_sp_is_unchanging)
4368 for (insn = f; insn; insn = NEXT_INSN (insn))
4372 /* Check if insn modifies the stack pointer. */
4373 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
4375 if (! current_function_sp_is_unchanging)
4381 /* Mark a register in SET. Hard registers in large modes get all
4382 of their component registers set as well. */
4385 mark_reg (reg, xset)
4389 regset set = (regset) xset;
4390 int regno = REGNO (reg);
4392 if (GET_MODE (reg) == BLKmode)
4395 SET_REGNO_REG_SET (set, regno);
4396 if (regno < FIRST_PSEUDO_REGISTER)
4398 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
4400 SET_REGNO_REG_SET (set, regno + n);
4404 /* Mark those regs which are needed at the end of the function as live
4405 at the end of the last basic block. */
4408 mark_regs_live_at_end (set)
4413 /* If exiting needs the right stack value, consider the stack pointer
4414 live at the end of the function. */
4415 if ((HAVE_epilogue && reload_completed)
4416 || ! EXIT_IGNORE_STACK
4417 || (! FRAME_POINTER_REQUIRED
4418 && ! current_function_calls_alloca
4419 && flag_omit_frame_pointer)
4420 || current_function_sp_is_unchanging)
4422 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
4425 /* Mark the frame pointer if needed at the end of the function. If
4426 we end up eliminating it, it will be removed from the live list
4427 of each basic block by reload. */
4429 if (! reload_completed || frame_pointer_needed)
4431 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
4432 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4433 /* If they are different, also mark the hard frame pointer as live. */
4434 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
4435 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
4439 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
4440 /* Many architectures have a GP register even without flag_pic.
4441 Assume the pic register is not in use, or will be handled by
4442 other means, if it is not fixed. */
4443 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4444 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4445 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
4448 /* Mark all global registers, and all registers used by the epilogue
4449 as being live at the end of the function since they may be
4450 referenced by our caller. */
4451 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4452 if (global_regs[i] || EPILOGUE_USES (i))
4453 SET_REGNO_REG_SET (set, i);
4455 if (HAVE_epilogue && reload_completed)
4457 /* Mark all call-saved registers that we actually used. */
4458 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
4459 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
4460 SET_REGNO_REG_SET (set, i);
4463 #ifdef EH_RETURN_DATA_REGNO
4464 /* Mark the registers that will contain data for the handler. */
4465 if (reload_completed && current_function_calls_eh_return)
4468 unsigned regno = EH_RETURN_DATA_REGNO(i);
4469 if (regno == INVALID_REGNUM)
4471 SET_REGNO_REG_SET (set, regno);
4474 #ifdef EH_RETURN_STACKADJ_RTX
4475 if ((! HAVE_epilogue || ! reload_completed)
4476 && current_function_calls_eh_return)
4478 rtx tmp = EH_RETURN_STACKADJ_RTX;
4479 if (tmp && REG_P (tmp))
4480 mark_reg (tmp, set);
4483 #ifdef EH_RETURN_HANDLER_RTX
4484 if ((! HAVE_epilogue || ! reload_completed)
4485 && current_function_calls_eh_return)
4487 rtx tmp = EH_RETURN_HANDLER_RTX;
4488 if (tmp && REG_P (tmp))
4489 mark_reg (tmp, set);
4493 /* Mark function return value. */
4494 diddle_return_value (mark_reg, set);
4497 /* Callback function for for_each_successor_phi. DATA is a regset.
4498 Sets the SRC_REGNO, the regno of the phi alternative for phi node
4499 INSN, in the regset. */
4502 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
4503 rtx insn ATTRIBUTE_UNUSED;
4504 int dest_regno ATTRIBUTE_UNUSED;
4508 regset live = (regset) data;
4509 SET_REGNO_REG_SET (live, src_regno);
4513 /* Propagate global life info around the graph of basic blocks. Begin
4514 considering blocks with their corresponding bit set in BLOCKS_IN.
4515 If BLOCKS_IN is null, consider it the universal set.
4517 BLOCKS_OUT is set for every block that was changed. */
4520 calculate_global_regs_live (blocks_in, blocks_out, flags)
4521 sbitmap blocks_in, blocks_out;
4524 basic_block *queue, *qhead, *qtail, *qend;
4525 regset tmp, new_live_at_end, call_used;
4526 regset_head tmp_head, call_used_head;
4527 regset_head new_live_at_end_head;
4530 tmp = INITIALIZE_REG_SET (tmp_head);
4531 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
4532 call_used = INITIALIZE_REG_SET (call_used_head);
4534 /* Inconveniently, this is only redily available in hard reg set form. */
4535 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
4536 if (call_used_regs[i])
4537 SET_REGNO_REG_SET (call_used, i);
4539 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
4540 because the `head == tail' style test for an empty queue doesn't
4541 work with a full queue. */
4542 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
4544 qhead = qend = queue + n_basic_blocks + 2;
4546 /* Queue the blocks set in the initial mask. Do this in reverse block
4547 number order so that we are more likely for the first round to do
4548 useful work. We use AUX non-null to flag that the block is queued. */
4551 /* Clear out the garbage that might be hanging out in bb->aux. */
4552 for (i = n_basic_blocks - 1; i >= 0; --i)
4553 BASIC_BLOCK (i)->aux = NULL;
4555 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
4557 basic_block bb = BASIC_BLOCK (i);
4564 for (i = 0; i < n_basic_blocks; ++i)
4566 basic_block bb = BASIC_BLOCK (i);
4573 sbitmap_zero (blocks_out);
4575 /* We work through the queue until there are no more blocks. What
4576 is live at the end of this block is precisely the union of what
4577 is live at the beginning of all its successors. So, we set its
4578 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
4579 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
4580 this block by walking through the instructions in this block in
4581 reverse order and updating as we go. If that changed
4582 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
4583 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
4585 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
4586 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
4587 must either be live at the end of the block, or used within the
4588 block. In the latter case, it will certainly never disappear
4589 from GLOBAL_LIVE_AT_START. In the former case, the register
4590 could go away only if it disappeared from GLOBAL_LIVE_AT_START
4591 for one of the successor blocks. By induction, that cannot
4593 while (qhead != qtail)
4595 int rescan, changed;
4604 /* Begin by propagating live_at_start from the successor blocks. */
4605 CLEAR_REG_SET (new_live_at_end);
4606 for (e = bb->succ; e; e = e->succ_next)
4608 basic_block sb = e->dest;
4610 /* Call-clobbered registers die across exception and call edges. */
4611 /* ??? Abnormal call edges ignored for the moment, as this gets
4612 confused by sibling call edges, which crashes reg-stack. */
4613 if (e->flags & EDGE_EH)
4615 bitmap_operation (tmp, sb->global_live_at_start,
4616 call_used, BITMAP_AND_COMPL);
4617 IOR_REG_SET (new_live_at_end, tmp);
4620 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
4623 /* The all-important stack pointer must always be live. */
4624 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
4626 /* Before reload, there are a few registers that must be forced
4627 live everywhere -- which might not already be the case for
4628 blocks within infinite loops. */
4629 if (! reload_completed)
4631 /* Any reference to any pseudo before reload is a potential
4632 reference of the frame pointer. */
4633 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
4635 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4636 /* Pseudos with argument area equivalences may require
4637 reloading via the argument pointer. */
4638 if (fixed_regs[ARG_POINTER_REGNUM])
4639 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
4642 /* Any constant, or pseudo with constant equivalences, may
4643 require reloading from memory using the pic register. */
4644 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
4645 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
4646 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
4649 /* Regs used in phi nodes are not included in
4650 global_live_at_start, since they are live only along a
4651 particular edge. Set those regs that are live because of a
4652 phi node alternative corresponding to this particular block. */
4654 for_each_successor_phi (bb, &set_phi_alternative_reg,
4657 if (bb == ENTRY_BLOCK_PTR)
4659 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4663 /* On our first pass through this block, we'll go ahead and continue.
4664 Recognize first pass by local_set NULL. On subsequent passes, we
4665 get to skip out early if live_at_end wouldn't have changed. */
4667 if (bb->local_set == NULL)
4669 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4670 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4675 /* If any bits were removed from live_at_end, we'll have to
4676 rescan the block. This wouldn't be necessary if we had
4677 precalculated local_live, however with PROP_SCAN_DEAD_CODE
4678 local_live is really dependent on live_at_end. */
4679 CLEAR_REG_SET (tmp);
4680 rescan = bitmap_operation (tmp, bb->global_live_at_end,
4681 new_live_at_end, BITMAP_AND_COMPL);
4685 /* If any of the registers in the new live_at_end set are
4686 conditionally set in this basic block, we must rescan.
4687 This is because conditional lifetimes at the end of the
4688 block do not just take the live_at_end set into account,
4689 but also the liveness at the start of each successor
4690 block. We can miss changes in those sets if we only
4691 compare the new live_at_end against the previous one. */
4692 CLEAR_REG_SET (tmp);
4693 rescan = bitmap_operation (tmp, new_live_at_end,
4694 bb->cond_local_set, BITMAP_AND);
4699 /* Find the set of changed bits. Take this opportunity
4700 to notice that this set is empty and early out. */
4701 CLEAR_REG_SET (tmp);
4702 changed = bitmap_operation (tmp, bb->global_live_at_end,
4703 new_live_at_end, BITMAP_XOR);
4707 /* If any of the changed bits overlap with local_set,
4708 we'll have to rescan the block. Detect overlap by
4709 the AND with ~local_set turning off bits. */
4710 rescan = bitmap_operation (tmp, tmp, bb->local_set,
4715 /* Let our caller know that BB changed enough to require its
4716 death notes updated. */
4718 SET_BIT (blocks_out, bb->index);
4722 /* Add to live_at_start the set of all registers in
4723 new_live_at_end that aren't in the old live_at_end. */
4725 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
4727 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4729 changed = bitmap_operation (bb->global_live_at_start,
4730 bb->global_live_at_start,
4737 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
4739 /* Rescan the block insn by insn to turn (a copy of) live_at_end
4740 into live_at_start. */
4741 propagate_block (bb, new_live_at_end, bb->local_set,
4742 bb->cond_local_set, flags);
4744 /* If live_at start didn't change, no need to go farther. */
4745 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
4748 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
4751 /* Queue all predecessors of BB so that we may re-examine
4752 their live_at_end. */
4753 for (e = bb->pred; e; e = e->pred_next)
4755 basic_block pb = e->src;
4756 if (pb->aux == NULL)
4767 FREE_REG_SET (new_live_at_end);
4768 FREE_REG_SET (call_used);
4772 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
4774 basic_block bb = BASIC_BLOCK (i);
4775 FREE_REG_SET (bb->local_set);
4776 FREE_REG_SET (bb->cond_local_set);
4781 for (i = n_basic_blocks - 1; i >= 0; --i)
4783 basic_block bb = BASIC_BLOCK (i);
4784 FREE_REG_SET (bb->local_set);
4785 FREE_REG_SET (bb->cond_local_set);
4792 /* Subroutines of life analysis. */
4794 /* Allocate the permanent data structures that represent the results
4795 of life analysis. Not static since used also for stupid life analysis. */
4798 allocate_bb_life_data ()
4802 for (i = 0; i < n_basic_blocks; i++)
4804 basic_block bb = BASIC_BLOCK (i);
4806 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4807 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4810 ENTRY_BLOCK_PTR->global_live_at_end
4811 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4812 EXIT_BLOCK_PTR->global_live_at_start
4813 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4815 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
4819 allocate_reg_life_data ()
4823 max_regno = max_reg_num ();
4825 /* Recalculate the register space, in case it has grown. Old style
4826 vector oriented regsets would set regset_{size,bytes} here also. */
4827 allocate_reg_info (max_regno, FALSE, FALSE);
4829 /* Reset all the data we'll collect in propagate_block and its
4831 for (i = 0; i < max_regno; i++)
4835 REG_N_DEATHS (i) = 0;
4836 REG_N_CALLS_CROSSED (i) = 0;
4837 REG_LIVE_LENGTH (i) = 0;
4838 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
4842 /* Delete dead instructions for propagate_block. */
4845 propagate_block_delete_insn (bb, insn)
4849 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
4851 /* If the insn referred to a label, and that label was attached to
4852 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
4853 pretty much mandatory to delete it, because the ADDR_VEC may be
4854 referencing labels that no longer exist.
4856 INSN may reference a deleted label, particularly when a jump
4857 table has been optimized into a direct jump. There's no
4858 real good way to fix up the reference to the deleted label
4859 when the label is deleted, so we just allow it here.
4861 After dead code elimination is complete, we do search for
4862 any REG_LABEL notes which reference deleted labels as a
4865 if (inote && GET_CODE (inote) == CODE_LABEL)
4867 rtx label = XEXP (inote, 0);
4870 /* The label may be forced if it has been put in the constant
4871 pool. If that is the only use we must discard the table
4872 jump following it, but not the label itself. */
4873 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
4874 && (next = next_nonnote_insn (label)) != NULL
4875 && GET_CODE (next) == JUMP_INSN
4876 && (GET_CODE (PATTERN (next)) == ADDR_VEC
4877 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
4879 rtx pat = PATTERN (next);
4880 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
4881 int len = XVECLEN (pat, diff_vec_p);
4884 for (i = 0; i < len; i++)
4885 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
4887 flow_delete_insn (next);
4891 if (bb->end == insn)
4892 bb->end = PREV_INSN (insn);
4893 flow_delete_insn (insn);
4896 /* Delete dead libcalls for propagate_block. Return the insn
4897 before the libcall. */
4900 propagate_block_delete_libcall (bb, insn, note)
4904 rtx first = XEXP (note, 0);
4905 rtx before = PREV_INSN (first);
4907 if (insn == bb->end)
4910 flow_delete_insn_chain (first, insn);
4914 /* Update the life-status of regs for one insn. Return the previous insn. */
4917 propagate_one_insn (pbi, insn)
4918 struct propagate_block_info *pbi;
4921 rtx prev = PREV_INSN (insn);
4922 int flags = pbi->flags;
4923 int insn_is_dead = 0;
4924 int libcall_is_dead = 0;
4928 if (! INSN_P (insn))
4931 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
4932 if (flags & PROP_SCAN_DEAD_CODE)
4934 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
4935 libcall_is_dead = (insn_is_dead && note != 0
4936 && libcall_dead_p (pbi, note, insn));
4939 /* If an instruction consists of just dead store(s) on final pass,
4941 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
4943 /* If we're trying to delete a prologue or epilogue instruction
4944 that isn't flagged as possibly being dead, something is wrong.
4945 But if we are keeping the stack pointer depressed, we might well
4946 be deleting insns that are used to compute the amount to update
4947 it by, so they are fine. */
4948 if (reload_completed
4949 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4950 && (TYPE_RETURNS_STACK_DEPRESSED
4951 (TREE_TYPE (current_function_decl))))
4952 && (((HAVE_epilogue || HAVE_prologue)
4953 && prologue_epilogue_contains (insn))
4954 || (HAVE_sibcall_epilogue
4955 && sibcall_epilogue_contains (insn)))
4956 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
4959 /* Record sets. Do this even for dead instructions, since they
4960 would have killed the values if they hadn't been deleted. */
4961 mark_set_regs (pbi, PATTERN (insn), insn);
4963 /* CC0 is now known to be dead. Either this insn used it,
4964 in which case it doesn't anymore, or clobbered it,
4965 so the next insn can't use it. */
4968 if (libcall_is_dead)
4969 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
4971 propagate_block_delete_insn (pbi->bb, insn);
4976 /* See if this is an increment or decrement that can be merged into
4977 a following memory address. */
4980 register rtx x = single_set (insn);
4982 /* Does this instruction increment or decrement a register? */
4983 if ((flags & PROP_AUTOINC)
4985 && GET_CODE (SET_DEST (x)) == REG
4986 && (GET_CODE (SET_SRC (x)) == PLUS
4987 || GET_CODE (SET_SRC (x)) == MINUS)
4988 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
4989 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
4990 /* Ok, look for a following memory ref we can combine with.
4991 If one is found, change the memory ref to a PRE_INC
4992 or PRE_DEC, cancel this insn, and return 1.
4993 Return 0 if nothing has been done. */
4994 && try_pre_increment_1 (pbi, insn))
4997 #endif /* AUTO_INC_DEC */
4999 CLEAR_REG_SET (pbi->new_set);
5001 /* If this is not the final pass, and this insn is copying the value of
5002 a library call and it's dead, don't scan the insns that perform the
5003 library call, so that the call's arguments are not marked live. */
5004 if (libcall_is_dead)
5006 /* Record the death of the dest reg. */
5007 mark_set_regs (pbi, PATTERN (insn), insn);
5009 insn = XEXP (note, 0);
5010 return PREV_INSN (insn);
5012 else if (GET_CODE (PATTERN (insn)) == SET
5013 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
5014 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
5015 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
5016 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
5017 /* We have an insn to pop a constant amount off the stack.
5018 (Such insns use PLUS regardless of the direction of the stack,
5019 and any insn to adjust the stack by a constant is always a pop.)
5020 These insns, if not dead stores, have no effect on life. */
5024 /* Any regs live at the time of a call instruction must not go
5025 in a register clobbered by calls. Find all regs now live and
5026 record this for them. */
5028 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
5029 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5030 { REG_N_CALLS_CROSSED (i)++; });
5032 /* Record sets. Do this even for dead instructions, since they
5033 would have killed the values if they hadn't been deleted. */
5034 mark_set_regs (pbi, PATTERN (insn), insn);
5036 if (GET_CODE (insn) == CALL_INSN)
5042 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5043 cond = COND_EXEC_TEST (PATTERN (insn));
5045 /* Non-constant calls clobber memory. */
5046 if (! CONST_CALL_P (insn))
5048 free_EXPR_LIST_list (&pbi->mem_set_list);
5049 pbi->mem_set_list_len = 0;
5052 /* There may be extra registers to be clobbered. */
5053 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5055 note = XEXP (note, 1))
5056 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
5057 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
5058 cond, insn, pbi->flags);
5060 /* Calls change all call-used and global registers. */
5061 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5062 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
5064 /* We do not want REG_UNUSED notes for these registers. */
5065 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
5067 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
5071 /* If an insn doesn't use CC0, it becomes dead since we assume
5072 that every insn clobbers it. So show it dead here;
5073 mark_used_regs will set it live if it is referenced. */
5078 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
5080 /* Sometimes we may have inserted something before INSN (such as a move)
5081 when we make an auto-inc. So ensure we will scan those insns. */
5083 prev = PREV_INSN (insn);
5086 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
5092 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
5093 cond = COND_EXEC_TEST (PATTERN (insn));
5095 /* Calls use their arguments. */
5096 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5098 note = XEXP (note, 1))
5099 if (GET_CODE (XEXP (note, 0)) == USE)
5100 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
5103 /* The stack ptr is used (honorarily) by a CALL insn. */
5104 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
5106 /* Calls may also reference any of the global registers,
5107 so they are made live. */
5108 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
5110 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
5115 /* On final pass, update counts of how many insns in which each reg
5117 if (flags & PROP_REG_INFO)
5118 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
5119 { REG_LIVE_LENGTH (i)++; });
5124 /* Initialize a propagate_block_info struct for public consumption.
5125 Note that the structure itself is opaque to this file, but that
5126 the user can use the regsets provided here. */
5128 struct propagate_block_info *
5129 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
5131 regset live, local_set, cond_local_set;
5134 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
5137 pbi->reg_live = live;
5138 pbi->mem_set_list = NULL_RTX;
5139 pbi->mem_set_list_len = 0;
5140 pbi->local_set = local_set;
5141 pbi->cond_local_set = cond_local_set;
5145 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5146 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
5148 pbi->reg_next_use = NULL;
5150 pbi->new_set = BITMAP_XMALLOC ();
5152 #ifdef HAVE_conditional_execution
5153 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
5154 free_reg_cond_life_info);
5155 pbi->reg_cond_reg = BITMAP_XMALLOC ();
5157 /* If this block ends in a conditional branch, for each register live
5158 from one side of the branch and not the other, record the register
5159 as conditionally dead. */
5160 if (GET_CODE (bb->end) == JUMP_INSN
5161 && any_condjump_p (bb->end))
5163 regset_head diff_head;
5164 regset diff = INITIALIZE_REG_SET (diff_head);
5165 basic_block bb_true, bb_false;
5166 rtx cond_true, cond_false, set_src;
5169 /* Identify the successor blocks. */
5170 bb_true = bb->succ->dest;
5171 if (bb->succ->succ_next != NULL)
5173 bb_false = bb->succ->succ_next->dest;
5175 if (bb->succ->flags & EDGE_FALLTHRU)
5177 basic_block t = bb_false;
5181 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
5186 /* This can happen with a conditional jump to the next insn. */
5187 if (JUMP_LABEL (bb->end) != bb_true->head)
5190 /* Simplest way to do nothing. */
5194 /* Extract the condition from the branch. */
5195 set_src = SET_SRC (pc_set (bb->end));
5196 cond_true = XEXP (set_src, 0);
5197 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
5198 GET_MODE (cond_true), XEXP (cond_true, 0),
5199 XEXP (cond_true, 1));
5200 if (GET_CODE (XEXP (set_src, 1)) == PC)
5203 cond_false = cond_true;
5207 /* Compute which register lead different lives in the successors. */
5208 if (bitmap_operation (diff, bb_true->global_live_at_start,
5209 bb_false->global_live_at_start, BITMAP_XOR))
5211 rtx reg = XEXP (cond_true, 0);
5213 if (GET_CODE (reg) == SUBREG)
5214 reg = SUBREG_REG (reg);
5216 if (GET_CODE (reg) != REG)
5219 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
5221 /* For each such register, mark it conditionally dead. */
5222 EXECUTE_IF_SET_IN_REG_SET
5225 struct reg_cond_life_info *rcli;
5228 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5230 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
5234 rcli->condition = cond;
5235 rcli->stores = const0_rtx;
5236 rcli->orig_condition = cond;
5238 splay_tree_insert (pbi->reg_cond_dead, i,
5239 (splay_tree_value) rcli);
5243 FREE_REG_SET (diff);
5247 /* If this block has no successors, any stores to the frame that aren't
5248 used later in the block are dead. So make a pass over the block
5249 recording any such that are made and show them dead at the end. We do
5250 a very conservative and simple job here. */
5252 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
5253 && (TYPE_RETURNS_STACK_DEPRESSED
5254 (TREE_TYPE (current_function_decl))))
5255 && (flags & PROP_SCAN_DEAD_CODE)
5256 && (bb->succ == NULL
5257 || (bb->succ->succ_next == NULL
5258 && bb->succ->dest == EXIT_BLOCK_PTR
5259 && ! current_function_calls_eh_return)))
5262 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
5263 if (GET_CODE (insn) == INSN
5264 && (set = single_set (insn))
5265 && GET_CODE (SET_DEST (set)) == MEM)
5267 rtx mem = SET_DEST (set);
5268 rtx canon_mem = canon_rtx (mem);
5270 /* This optimization is performed by faking a store to the
5271 memory at the end of the block. This doesn't work for
5272 unchanging memories because multiple stores to unchanging
5273 memory is illegal and alias analysis doesn't consider it. */
5274 if (RTX_UNCHANGING_P (canon_mem))
5277 if (XEXP (canon_mem, 0) == frame_pointer_rtx
5278 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
5279 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
5280 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
5283 /* Store a copy of mem, otherwise the address may be scrogged
5284 by find_auto_inc. This matters because insn_dead_p uses
5285 an rtx_equal_p check to determine if two addresses are
5286 the same. This works before find_auto_inc, but fails
5287 after find_auto_inc, causing discrepencies between the
5288 set of live registers calculated during the
5289 calculate_global_regs_live phase and what actually exists
5290 after flow completes, leading to aborts. */
5291 if (flags & PROP_AUTOINC)
5292 mem = shallow_copy_rtx (mem);
5294 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
5295 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
5304 /* Release a propagate_block_info struct. */
5307 free_propagate_block_info (pbi)
5308 struct propagate_block_info *pbi;
5310 free_EXPR_LIST_list (&pbi->mem_set_list);
5312 BITMAP_XFREE (pbi->new_set);
5314 #ifdef HAVE_conditional_execution
5315 splay_tree_delete (pbi->reg_cond_dead);
5316 BITMAP_XFREE (pbi->reg_cond_reg);
5319 if (pbi->reg_next_use)
5320 free (pbi->reg_next_use);
5325 /* Compute the registers live at the beginning of a basic block BB from
5326 those live at the end.
5328 When called, REG_LIVE contains those live at the end. On return, it
5329 contains those live at the beginning.
5331 LOCAL_SET, if non-null, will be set with all registers killed
5332 unconditionally by this basic block.
5333 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
5334 killed conditionally by this basic block. If there is any unconditional
5335 set of a register, then the corresponding bit will be set in LOCAL_SET
5336 and cleared in COND_LOCAL_SET.
5337 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
5338 case, the resulting set will be equal to the union of the two sets that
5339 would otherwise be computed. */
5342 propagate_block (bb, live, local_set, cond_local_set, flags)
5346 regset cond_local_set;
5349 struct propagate_block_info *pbi;
5352 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
5354 if (flags & PROP_REG_INFO)
5358 /* Process the regs live at the end of the block.
5359 Mark them as not local to any one basic block. */
5360 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
5361 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
5364 /* Scan the block an insn at a time from end to beginning. */
5366 for (insn = bb->end;; insn = prev)
5368 /* If this is a call to `setjmp' et al, warn if any
5369 non-volatile datum is live. */
5370 if ((flags & PROP_REG_INFO)
5371 && GET_CODE (insn) == NOTE
5372 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
5373 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
5375 prev = propagate_one_insn (pbi, insn);
5377 if (insn == bb->head)
5381 free_propagate_block_info (pbi);
5384 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
5385 (SET expressions whose destinations are registers dead after the insn).
5386 NEEDED is the regset that says which regs are alive after the insn.
5388 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
5390 If X is the entire body of an insn, NOTES contains the reg notes
5391 pertaining to the insn. */
5394 insn_dead_p (pbi, x, call_ok, notes)
5395 struct propagate_block_info *pbi;
5398 rtx notes ATTRIBUTE_UNUSED;
5400 enum rtx_code code = GET_CODE (x);
5403 /* If flow is invoked after reload, we must take existing AUTO_INC
5404 expresions into account. */
5405 if (reload_completed)
5407 for (; notes; notes = XEXP (notes, 1))
5409 if (REG_NOTE_KIND (notes) == REG_INC)
5411 int regno = REGNO (XEXP (notes, 0));
5413 /* Don't delete insns to set global regs. */
5414 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5415 || REGNO_REG_SET_P (pbi->reg_live, regno))
5422 /* If setting something that's a reg or part of one,
5423 see if that register's altered value will be live. */
5427 rtx r = SET_DEST (x);
5430 if (GET_CODE (r) == CC0)
5431 return ! pbi->cc0_live;
5434 /* A SET that is a subroutine call cannot be dead. */
5435 if (GET_CODE (SET_SRC (x)) == CALL)
5441 /* Don't eliminate loads from volatile memory or volatile asms. */
5442 else if (volatile_refs_p (SET_SRC (x)))
5445 if (GET_CODE (r) == MEM)
5449 if (MEM_VOLATILE_P (r))
5452 /* Walk the set of memory locations we are currently tracking
5453 and see if one is an identical match to this memory location.
5454 If so, this memory write is dead (remember, we're walking
5455 backwards from the end of the block to the start). Since
5456 rtx_equal_p does not check the alias set or flags, we also
5457 must have the potential for them to conflict (anti_dependence). */
5458 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
5459 if (anti_dependence (r, XEXP (temp, 0)))
5461 rtx mem = XEXP (temp, 0);
5463 if (rtx_equal_p (mem, r))
5466 /* Check if memory reference matches an auto increment. Only
5467 post increment/decrement or modify are valid. */
5468 if (GET_MODE (mem) == GET_MODE (r)
5469 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
5470 || GET_CODE (XEXP (mem, 0)) == POST_INC
5471 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
5472 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
5473 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
5480 while (GET_CODE (r) == SUBREG
5481 || GET_CODE (r) == STRICT_LOW_PART
5482 || GET_CODE (r) == ZERO_EXTRACT)
5485 if (GET_CODE (r) == REG)
5487 int regno = REGNO (r);
5490 if (REGNO_REG_SET_P (pbi->reg_live, regno))
5493 /* If this is a hard register, verify that subsequent
5494 words are not needed. */
5495 if (regno < FIRST_PSEUDO_REGISTER)
5497 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
5500 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
5504 /* Don't delete insns to set global regs. */
5505 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
5508 /* Make sure insns to set the stack pointer aren't deleted. */
5509 if (regno == STACK_POINTER_REGNUM)
5512 /* ??? These bits might be redundant with the force live bits
5513 in calculate_global_regs_live. We would delete from
5514 sequential sets; whether this actually affects real code
5515 for anything but the stack pointer I don't know. */
5516 /* Make sure insns to set the frame pointer aren't deleted. */
5517 if (regno == FRAME_POINTER_REGNUM
5518 && (! reload_completed || frame_pointer_needed))
5520 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5521 if (regno == HARD_FRAME_POINTER_REGNUM
5522 && (! reload_completed || frame_pointer_needed))
5526 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5527 /* Make sure insns to set arg pointer are never deleted
5528 (if the arg pointer isn't fixed, there will be a USE
5529 for it, so we can treat it normally). */
5530 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5534 /* Otherwise, the set is dead. */
5540 /* If performing several activities, insn is dead if each activity
5541 is individually dead. Also, CLOBBERs and USEs can be ignored; a
5542 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
5544 else if (code == PARALLEL)
5546 int i = XVECLEN (x, 0);
5548 for (i--; i >= 0; i--)
5549 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
5550 && GET_CODE (XVECEXP (x, 0, i)) != USE
5551 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
5557 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
5558 is not necessarily true for hard registers. */
5559 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
5560 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
5561 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
5564 /* We do not check other CLOBBER or USE here. An insn consisting of just
5565 a CLOBBER or just a USE should not be deleted. */
5569 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
5570 return 1 if the entire library call is dead.
5571 This is true if INSN copies a register (hard or pseudo)
5572 and if the hard return reg of the call insn is dead.
5573 (The caller should have tested the destination of the SET inside
5574 INSN already for death.)
5576 If this insn doesn't just copy a register, then we don't
5577 have an ordinary libcall. In that case, cse could not have
5578 managed to substitute the source for the dest later on,
5579 so we can assume the libcall is dead.
5581 PBI is the block info giving pseudoregs live before this insn.
5582 NOTE is the REG_RETVAL note of the insn. */
5585 libcall_dead_p (pbi, note, insn)
5586 struct propagate_block_info *pbi;
5590 rtx x = single_set (insn);
5594 register rtx r = SET_SRC (x);
5595 if (GET_CODE (r) == REG)
5597 rtx call = XEXP (note, 0);
5601 /* Find the call insn. */
5602 while (call != insn && GET_CODE (call) != CALL_INSN)
5603 call = NEXT_INSN (call);
5605 /* If there is none, do nothing special,
5606 since ordinary death handling can understand these insns. */
5610 /* See if the hard reg holding the value is dead.
5611 If this is a PARALLEL, find the call within it. */
5612 call_pat = PATTERN (call);
5613 if (GET_CODE (call_pat) == PARALLEL)
5615 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
5616 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
5617 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
5620 /* This may be a library call that is returning a value
5621 via invisible pointer. Do nothing special, since
5622 ordinary death handling can understand these insns. */
5626 call_pat = XVECEXP (call_pat, 0, i);
5629 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
5635 /* Return 1 if register REGNO was used before it was set, i.e. if it is
5636 live at function entry. Don't count global register variables, variables
5637 in registers that can be used for function arg passing, or variables in
5638 fixed hard registers. */
5641 regno_uninitialized (regno)
5644 if (n_basic_blocks == 0
5645 || (regno < FIRST_PSEUDO_REGISTER
5646 && (global_regs[regno]
5647 || fixed_regs[regno]
5648 || FUNCTION_ARG_REGNO_P (regno))))
5651 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
5654 /* 1 if register REGNO was alive at a place where `setjmp' was called
5655 and was set more than once or is an argument.
5656 Such regs may be clobbered by `longjmp'. */
5659 regno_clobbered_at_setjmp (regno)
5662 if (n_basic_blocks == 0)
5665 return ((REG_N_SETS (regno) > 1
5666 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
5667 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
5670 /* INSN references memory, possibly using autoincrement addressing modes.
5671 Find any entries on the mem_set_list that need to be invalidated due
5672 to an address change. */
5675 invalidate_mems_from_autoinc (pbi, insn)
5676 struct propagate_block_info *pbi;
5679 rtx note = REG_NOTES (insn);
5680 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
5682 if (REG_NOTE_KIND (note) == REG_INC)
5684 rtx temp = pbi->mem_set_list;
5685 rtx prev = NULL_RTX;
5690 next = XEXP (temp, 1);
5691 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
5693 /* Splice temp out of list. */
5695 XEXP (prev, 1) = next;
5697 pbi->mem_set_list = next;
5698 free_EXPR_LIST_node (temp);
5699 pbi->mem_set_list_len--;
5709 /* EXP is either a MEM or a REG. Remove any dependant entries
5710 from pbi->mem_set_list. */
5713 invalidate_mems_from_set (pbi, exp)
5714 struct propagate_block_info *pbi;
5717 rtx temp = pbi->mem_set_list;
5718 rtx prev = NULL_RTX;
5723 next = XEXP (temp, 1);
5724 if ((GET_CODE (exp) == MEM
5725 && output_dependence (XEXP (temp, 0), exp))
5726 || (GET_CODE (exp) == REG
5727 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
5729 /* Splice this entry out of the list. */
5731 XEXP (prev, 1) = next;
5733 pbi->mem_set_list = next;
5734 free_EXPR_LIST_node (temp);
5735 pbi->mem_set_list_len--;
5743 /* Process the registers that are set within X. Their bits are set to
5744 1 in the regset DEAD, because they are dead prior to this insn.
5746 If INSN is nonzero, it is the insn being processed.
5748 FLAGS is the set of operations to perform. */
5751 mark_set_regs (pbi, x, insn)
5752 struct propagate_block_info *pbi;
5755 rtx cond = NULL_RTX;
5760 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
5762 if (REG_NOTE_KIND (link) == REG_INC)
5763 mark_set_1 (pbi, SET, XEXP (link, 0),
5764 (GET_CODE (x) == COND_EXEC
5765 ? COND_EXEC_TEST (x) : NULL_RTX),
5769 switch (code = GET_CODE (x))
5773 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
5777 cond = COND_EXEC_TEST (x);
5778 x = COND_EXEC_CODE (x);
5784 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
5786 rtx sub = XVECEXP (x, 0, i);
5787 switch (code = GET_CODE (sub))
5790 if (cond != NULL_RTX)
5793 cond = COND_EXEC_TEST (sub);
5794 sub = COND_EXEC_CODE (sub);
5795 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
5801 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
5816 /* Process a single set, which appears in INSN. REG (which may not
5817 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
5818 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
5819 If the set is conditional (because it appear in a COND_EXEC), COND
5820 will be the condition. */
5823 mark_set_1 (pbi, code, reg, cond, insn, flags)
5824 struct propagate_block_info *pbi;
5826 rtx reg, cond, insn;
5829 int regno_first = -1, regno_last = -1;
5830 unsigned long not_dead = 0;
5833 /* Modifying just one hardware register of a multi-reg value or just a
5834 byte field of a register does not mean the value from before this insn
5835 is now dead. Of course, if it was dead after it's unused now. */
5837 switch (GET_CODE (reg))
5840 /* Some targets place small structures in registers for return values of
5841 functions. We have to detect this case specially here to get correct
5842 flow information. */
5843 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
5844 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
5845 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
5851 case STRICT_LOW_PART:
5852 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
5854 reg = XEXP (reg, 0);
5855 while (GET_CODE (reg) == SUBREG
5856 || GET_CODE (reg) == ZERO_EXTRACT
5857 || GET_CODE (reg) == SIGN_EXTRACT
5858 || GET_CODE (reg) == STRICT_LOW_PART);
5859 if (GET_CODE (reg) == MEM)
5861 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
5865 regno_last = regno_first = REGNO (reg);
5866 if (regno_first < FIRST_PSEUDO_REGISTER)
5867 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
5871 if (GET_CODE (SUBREG_REG (reg)) == REG)
5873 enum machine_mode outer_mode = GET_MODE (reg);
5874 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
5876 /* Identify the range of registers affected. This is moderately
5877 tricky for hard registers. See alter_subreg. */
5879 regno_last = regno_first = REGNO (SUBREG_REG (reg));
5880 if (regno_first < FIRST_PSEUDO_REGISTER)
5882 regno_first += subreg_regno_offset (regno_first, inner_mode,
5885 regno_last = (regno_first
5886 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
5888 /* Since we've just adjusted the register number ranges, make
5889 sure REG matches. Otherwise some_was_live will be clear
5890 when it shouldn't have been, and we'll create incorrect
5891 REG_UNUSED notes. */
5892 reg = gen_rtx_REG (outer_mode, regno_first);
5896 /* If the number of words in the subreg is less than the number
5897 of words in the full register, we have a well-defined partial
5898 set. Otherwise the high bits are undefined.
5900 This is only really applicable to pseudos, since we just took
5901 care of multi-word hard registers. */
5902 if (((GET_MODE_SIZE (outer_mode)
5903 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
5904 < ((GET_MODE_SIZE (inner_mode)
5905 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
5906 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
5909 reg = SUBREG_REG (reg);
5913 reg = SUBREG_REG (reg);
5920 /* If this set is a MEM, then it kills any aliased writes.
5921 If this set is a REG, then it kills any MEMs which use the reg. */
5922 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5924 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
5925 invalidate_mems_from_set (pbi, reg);
5927 /* If the memory reference had embedded side effects (autoincrement
5928 address modes. Then we may need to kill some entries on the
5930 if (insn && GET_CODE (reg) == MEM)
5931 invalidate_mems_from_autoinc (pbi, insn);
5933 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
5934 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
5935 /* ??? With more effort we could track conditional memory life. */
5937 /* We do not know the size of a BLKmode store, so we do not track
5938 them for redundant store elimination. */
5939 && GET_MODE (reg) != BLKmode
5940 /* There are no REG_INC notes for SP, so we can't assume we'll see
5941 everything that invalidates it. To be safe, don't eliminate any
5942 stores though SP; none of them should be redundant anyway. */
5943 && ! reg_mentioned_p (stack_pointer_rtx, reg))
5946 /* Store a copy of mem, otherwise the address may be
5947 scrogged by find_auto_inc. */
5948 if (flags & PROP_AUTOINC)
5949 reg = shallow_copy_rtx (reg);
5951 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
5952 pbi->mem_set_list_len++;
5956 if (GET_CODE (reg) == REG
5957 && ! (regno_first == FRAME_POINTER_REGNUM
5958 && (! reload_completed || frame_pointer_needed))
5959 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5960 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
5961 && (! reload_completed || frame_pointer_needed))
5963 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5964 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
5968 int some_was_live = 0, some_was_dead = 0;
5970 for (i = regno_first; i <= regno_last; ++i)
5972 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
5975 /* Order of the set operation matters here since both
5976 sets may be the same. */
5977 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
5978 if (cond != NULL_RTX
5979 && ! REGNO_REG_SET_P (pbi->local_set, i))
5980 SET_REGNO_REG_SET (pbi->cond_local_set, i);
5982 SET_REGNO_REG_SET (pbi->local_set, i);
5984 if (code != CLOBBER)
5985 SET_REGNO_REG_SET (pbi->new_set, i);
5987 some_was_live |= needed_regno;
5988 some_was_dead |= ! needed_regno;
5991 #ifdef HAVE_conditional_execution
5992 /* Consider conditional death in deciding that the register needs
5994 if (some_was_live && ! not_dead
5995 /* The stack pointer is never dead. Well, not strictly true,
5996 but it's very difficult to tell from here. Hopefully
5997 combine_stack_adjustments will fix up the most egregious
5999 && regno_first != STACK_POINTER_REGNUM)
6001 for (i = regno_first; i <= regno_last; ++i)
6002 if (! mark_regno_cond_dead (pbi, i, cond))
6003 not_dead |= ((unsigned long) 1) << (i - regno_first);
6007 /* Additional data to record if this is the final pass. */
6008 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
6009 | PROP_DEATH_NOTES | PROP_AUTOINC))
6012 register int blocknum = pbi->bb->index;
6015 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6017 y = pbi->reg_next_use[regno_first];
6019 /* The next use is no longer next, since a store intervenes. */
6020 for (i = regno_first; i <= regno_last; ++i)
6021 pbi->reg_next_use[i] = 0;
6024 if (flags & PROP_REG_INFO)
6026 for (i = regno_first; i <= regno_last; ++i)
6028 /* Count (weighted) references, stores, etc. This counts a
6029 register twice if it is modified, but that is correct. */
6030 REG_N_SETS (i) += 1;
6031 REG_N_REFS (i) += 1;
6032 REG_FREQ (i) += (optimize_size || !pbi->bb->frequency
6033 ? 1 : pbi->bb->frequency);
6035 /* The insns where a reg is live are normally counted
6036 elsewhere, but we want the count to include the insn
6037 where the reg is set, and the normal counting mechanism
6038 would not count it. */
6039 REG_LIVE_LENGTH (i) += 1;
6042 /* If this is a hard reg, record this function uses the reg. */
6043 if (regno_first < FIRST_PSEUDO_REGISTER)
6045 for (i = regno_first; i <= regno_last; i++)
6046 regs_ever_live[i] = 1;
6050 /* Keep track of which basic blocks each reg appears in. */
6051 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6052 REG_BASIC_BLOCK (regno_first) = blocknum;
6053 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6054 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6058 if (! some_was_dead)
6060 if (flags & PROP_LOG_LINKS)
6062 /* Make a logical link from the next following insn
6063 that uses this register, back to this insn.
6064 The following insns have already been processed.
6066 We don't build a LOG_LINK for hard registers containing
6067 in ASM_OPERANDs. If these registers get replaced,
6068 we might wind up changing the semantics of the insn,
6069 even if reload can make what appear to be valid
6070 assignments later. */
6071 if (y && (BLOCK_NUM (y) == blocknum)
6072 && (regno_first >= FIRST_PSEUDO_REGISTER
6073 || asm_noperands (PATTERN (y)) < 0))
6074 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
6079 else if (! some_was_live)
6081 if (flags & PROP_REG_INFO)
6082 REG_N_DEATHS (regno_first) += 1;
6084 if (flags & PROP_DEATH_NOTES)
6086 /* Note that dead stores have already been deleted
6087 when possible. If we get here, we have found a
6088 dead store that cannot be eliminated (because the
6089 same insn does something useful). Indicate this
6090 by marking the reg being set as dying here. */
6092 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6097 if (flags & PROP_DEATH_NOTES)
6099 /* This is a case where we have a multi-word hard register
6100 and some, but not all, of the words of the register are
6101 needed in subsequent insns. Write REG_UNUSED notes
6102 for those parts that were not needed. This case should
6105 for (i = regno_first; i <= regno_last; ++i)
6106 if (! REGNO_REG_SET_P (pbi->reg_live, i))
6108 = alloc_EXPR_LIST (REG_UNUSED,
6109 gen_rtx_REG (reg_raw_mode[i], i),
6115 /* Mark the register as being dead. */
6117 /* The stack pointer is never dead. Well, not strictly true,
6118 but it's very difficult to tell from here. Hopefully
6119 combine_stack_adjustments will fix up the most egregious
6121 && regno_first != STACK_POINTER_REGNUM)
6123 for (i = regno_first; i <= regno_last; ++i)
6124 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
6125 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
6128 else if (GET_CODE (reg) == REG)
6130 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6131 pbi->reg_next_use[regno_first] = 0;
6134 /* If this is the last pass and this is a SCRATCH, show it will be dying
6135 here and count it. */
6136 else if (GET_CODE (reg) == SCRATCH)
6138 if (flags & PROP_DEATH_NOTES)
6140 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
6144 #ifdef HAVE_conditional_execution
6145 /* Mark REGNO conditionally dead.
6146 Return true if the register is now unconditionally dead. */
6149 mark_regno_cond_dead (pbi, regno, cond)
6150 struct propagate_block_info *pbi;
6154 /* If this is a store to a predicate register, the value of the
6155 predicate is changing, we don't know that the predicate as seen
6156 before is the same as that seen after. Flush all dependent
6157 conditions from reg_cond_dead. This will make all such
6158 conditionally live registers unconditionally live. */
6159 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
6160 flush_reg_cond_reg (pbi, regno);
6162 /* If this is an unconditional store, remove any conditional
6163 life that may have existed. */
6164 if (cond == NULL_RTX)
6165 splay_tree_remove (pbi->reg_cond_dead, regno);
6168 splay_tree_node node;
6169 struct reg_cond_life_info *rcli;
6172 /* Otherwise this is a conditional set. Record that fact.
6173 It may have been conditionally used, or there may be a
6174 subsequent set with a complimentary condition. */
6176 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
6179 /* The register was unconditionally live previously.
6180 Record the current condition as the condition under
6181 which it is dead. */
6182 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6183 rcli->condition = cond;
6184 rcli->stores = cond;
6185 rcli->orig_condition = const0_rtx;
6186 splay_tree_insert (pbi->reg_cond_dead, regno,
6187 (splay_tree_value) rcli);
6189 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6191 /* Not unconditionaly dead. */
6196 /* The register was conditionally live previously.
6197 Add the new condition to the old. */
6198 rcli = (struct reg_cond_life_info *) node->value;
6199 ncond = rcli->condition;
6200 ncond = ior_reg_cond (ncond, cond, 1);
6201 if (rcli->stores == const0_rtx)
6202 rcli->stores = cond;
6203 else if (rcli->stores != const1_rtx)
6204 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
6206 /* If the register is now unconditionally dead, remove the entry
6207 in the splay_tree. A register is unconditionally dead if the
6208 dead condition ncond is true. A register is also unconditionally
6209 dead if the sum of all conditional stores is an unconditional
6210 store (stores is true), and the dead condition is identically the
6211 same as the original dead condition initialized at the end of
6212 the block. This is a pointer compare, not an rtx_equal_p
6214 if (ncond == const1_rtx
6215 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
6216 splay_tree_remove (pbi->reg_cond_dead, regno);
6219 rcli->condition = ncond;
6221 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6223 /* Not unconditionaly dead. */
6232 /* Called from splay_tree_delete for pbi->reg_cond_life. */
6235 free_reg_cond_life_info (value)
6236 splay_tree_value value;
6238 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
6242 /* Helper function for flush_reg_cond_reg. */
6245 flush_reg_cond_reg_1 (node, data)
6246 splay_tree_node node;
6249 struct reg_cond_life_info *rcli;
6250 int *xdata = (int *) data;
6251 unsigned int regno = xdata[0];
6253 /* Don't need to search if last flushed value was farther on in
6254 the in-order traversal. */
6255 if (xdata[1] >= (int) node->key)
6258 /* Splice out portions of the expression that refer to regno. */
6259 rcli = (struct reg_cond_life_info *) node->value;
6260 rcli->condition = elim_reg_cond (rcli->condition, regno);
6261 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
6262 rcli->stores = elim_reg_cond (rcli->stores, regno);
6264 /* If the entire condition is now false, signal the node to be removed. */
6265 if (rcli->condition == const0_rtx)
6267 xdata[1] = node->key;
6270 else if (rcli->condition == const1_rtx)
6276 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
6279 flush_reg_cond_reg (pbi, regno)
6280 struct propagate_block_info *pbi;
6287 while (splay_tree_foreach (pbi->reg_cond_dead,
6288 flush_reg_cond_reg_1, pair) == -1)
6289 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
6291 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
6294 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
6295 For ior/and, the ADD flag determines whether we want to add the new
6296 condition X to the old one unconditionally. If it is zero, we will
6297 only return a new expression if X allows us to simplify part of
6298 OLD, otherwise we return OLD unchanged to the caller.
6299 If ADD is nonzero, we will return a new condition in all cases. The
6300 toplevel caller of one of these functions should always pass 1 for
6304 ior_reg_cond (old, x, add)
6310 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6312 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6313 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
6314 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6316 if (GET_CODE (x) == GET_CODE (old)
6317 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6321 return gen_rtx_IOR (0, old, x);
6324 switch (GET_CODE (old))
6327 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6328 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6329 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6331 if (op0 == const0_rtx)
6333 if (op1 == const0_rtx)
6335 if (op0 == const1_rtx || op1 == const1_rtx)
6337 if (op0 == XEXP (old, 0))
6338 op0 = gen_rtx_IOR (0, op0, x);
6340 op1 = gen_rtx_IOR (0, op1, x);
6341 return gen_rtx_IOR (0, op0, op1);
6345 return gen_rtx_IOR (0, old, x);
6348 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
6349 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
6350 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6352 if (op0 == const1_rtx)
6354 if (op1 == const1_rtx)
6356 if (op0 == const0_rtx || op1 == const0_rtx)
6358 if (op0 == XEXP (old, 0))
6359 op0 = gen_rtx_IOR (0, op0, x);
6361 op1 = gen_rtx_IOR (0, op1, x);
6362 return gen_rtx_AND (0, op0, op1);
6366 return gen_rtx_IOR (0, old, x);
6369 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6370 if (op0 != XEXP (old, 0))
6371 return not_reg_cond (op0);
6374 return gen_rtx_IOR (0, old, x);
6385 enum rtx_code x_code;
6387 if (x == const0_rtx)
6389 else if (x == const1_rtx)
6391 x_code = GET_CODE (x);
6394 if (GET_RTX_CLASS (x_code) == '<'
6395 && GET_CODE (XEXP (x, 0)) == REG)
6397 if (XEXP (x, 1) != const0_rtx)
6400 return gen_rtx_fmt_ee (reverse_condition (x_code),
6401 VOIDmode, XEXP (x, 0), const0_rtx);
6403 return gen_rtx_NOT (0, x);
6407 and_reg_cond (old, x, add)
6413 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
6415 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
6416 && GET_CODE (x) == reverse_condition (GET_CODE (old))
6417 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6419 if (GET_CODE (x) == GET_CODE (old)
6420 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
6424 return gen_rtx_AND (0, old, x);
6427 switch (GET_CODE (old))
6430 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6431 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6432 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6434 if (op0 == const0_rtx)
6436 if (op1 == const0_rtx)
6438 if (op0 == const1_rtx || op1 == const1_rtx)
6440 if (op0 == XEXP (old, 0))
6441 op0 = gen_rtx_AND (0, op0, x);
6443 op1 = gen_rtx_AND (0, op1, x);
6444 return gen_rtx_IOR (0, op0, op1);
6448 return gen_rtx_AND (0, old, x);
6451 op0 = and_reg_cond (XEXP (old, 0), x, 0);
6452 op1 = and_reg_cond (XEXP (old, 1), x, 0);
6453 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
6455 if (op0 == const1_rtx)
6457 if (op1 == const1_rtx)
6459 if (op0 == const0_rtx || op1 == const0_rtx)
6461 if (op0 == XEXP (old, 0))
6462 op0 = gen_rtx_AND (0, op0, x);
6464 op1 = gen_rtx_AND (0, op1, x);
6465 return gen_rtx_AND (0, op0, op1);
6470 /* If X is identical to one of the existing terms of the AND,
6471 then just return what we already have. */
6472 /* ??? There really should be some sort of recursive check here in
6473 case there are nested ANDs. */
6474 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
6475 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
6476 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
6477 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
6480 return gen_rtx_AND (0, old, x);
6483 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
6484 if (op0 != XEXP (old, 0))
6485 return not_reg_cond (op0);
6488 return gen_rtx_AND (0, old, x);
6495 /* Given a condition X, remove references to reg REGNO and return the
6496 new condition. The removal will be done so that all conditions
6497 involving REGNO are considered to evaluate to false. This function
6498 is used when the value of REGNO changes. */
6501 elim_reg_cond (x, regno)
6507 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
6509 if (REGNO (XEXP (x, 0)) == regno)
6514 switch (GET_CODE (x))
6517 op0 = elim_reg_cond (XEXP (x, 0), regno);
6518 op1 = elim_reg_cond (XEXP (x, 1), regno);
6519 if (op0 == const0_rtx || op1 == const0_rtx)
6521 if (op0 == const1_rtx)
6523 if (op1 == const1_rtx)
6525 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6527 return gen_rtx_AND (0, op0, op1);
6530 op0 = elim_reg_cond (XEXP (x, 0), regno);
6531 op1 = elim_reg_cond (XEXP (x, 1), regno);
6532 if (op0 == const1_rtx || op1 == const1_rtx)
6534 if (op0 == const0_rtx)
6536 if (op1 == const0_rtx)
6538 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
6540 return gen_rtx_IOR (0, op0, op1);
6543 op0 = elim_reg_cond (XEXP (x, 0), regno);
6544 if (op0 == const0_rtx)
6546 if (op0 == const1_rtx)
6548 if (op0 != XEXP (x, 0))
6549 return not_reg_cond (op0);
6556 #endif /* HAVE_conditional_execution */
6560 /* Try to substitute the auto-inc expression INC as the address inside
6561 MEM which occurs in INSN. Currently, the address of MEM is an expression
6562 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
6563 that has a single set whose source is a PLUS of INCR_REG and something
6567 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
6568 struct propagate_block_info *pbi;
6569 rtx inc, insn, mem, incr, incr_reg;
6571 int regno = REGNO (incr_reg);
6572 rtx set = single_set (incr);
6573 rtx q = SET_DEST (set);
6574 rtx y = SET_SRC (set);
6575 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
6577 /* Make sure this reg appears only once in this insn. */
6578 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
6581 if (dead_or_set_p (incr, incr_reg)
6582 /* Mustn't autoinc an eliminable register. */
6583 && (regno >= FIRST_PSEUDO_REGISTER
6584 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
6586 /* This is the simple case. Try to make the auto-inc. If
6587 we can't, we are done. Otherwise, we will do any
6588 needed updates below. */
6589 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
6592 else if (GET_CODE (q) == REG
6593 /* PREV_INSN used here to check the semi-open interval
6595 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
6596 /* We must also check for sets of q as q may be
6597 a call clobbered hard register and there may
6598 be a call between PREV_INSN (insn) and incr. */
6599 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
6601 /* We have *p followed sometime later by q = p+size.
6602 Both p and q must be live afterward,
6603 and q is not used between INSN and its assignment.
6604 Change it to q = p, ...*q..., q = q+size.
6605 Then fall into the usual case. */
6609 emit_move_insn (q, incr_reg);
6610 insns = get_insns ();
6613 if (basic_block_for_insn)
6614 for (temp = insns; temp; temp = NEXT_INSN (temp))
6615 set_block_for_insn (temp, pbi->bb);
6617 /* If we can't make the auto-inc, or can't make the
6618 replacement into Y, exit. There's no point in making
6619 the change below if we can't do the auto-inc and doing
6620 so is not correct in the pre-inc case. */
6623 validate_change (insn, &XEXP (mem, 0), inc, 1);
6624 validate_change (incr, &XEXP (y, opnum), q, 1);
6625 if (! apply_change_group ())
6628 /* We now know we'll be doing this change, so emit the
6629 new insn(s) and do the updates. */
6630 emit_insns_before (insns, insn);
6632 if (pbi->bb->head == insn)
6633 pbi->bb->head = insns;
6635 /* INCR will become a NOTE and INSN won't contain a
6636 use of INCR_REG. If a use of INCR_REG was just placed in
6637 the insn before INSN, make that the next use.
6638 Otherwise, invalidate it. */
6639 if (GET_CODE (PREV_INSN (insn)) == INSN
6640 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
6641 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
6642 pbi->reg_next_use[regno] = PREV_INSN (insn);
6644 pbi->reg_next_use[regno] = 0;
6649 /* REGNO is now used in INCR which is below INSN, but
6650 it previously wasn't live here. If we don't mark
6651 it as live, we'll put a REG_DEAD note for it
6652 on this insn, which is incorrect. */
6653 SET_REGNO_REG_SET (pbi->reg_live, regno);
6655 /* If there are any calls between INSN and INCR, show
6656 that REGNO now crosses them. */
6657 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
6658 if (GET_CODE (temp) == CALL_INSN)
6659 REG_N_CALLS_CROSSED (regno)++;
6664 /* If we haven't returned, it means we were able to make the
6665 auto-inc, so update the status. First, record that this insn
6666 has an implicit side effect. */
6668 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
6670 /* Modify the old increment-insn to simply copy
6671 the already-incremented value of our register. */
6672 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
6675 /* If that makes it a no-op (copying the register into itself) delete
6676 it so it won't appear to be a "use" and a "set" of this
6678 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
6680 /* If the original source was dead, it's dead now. */
6683 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
6685 remove_note (incr, note);
6686 if (XEXP (note, 0) != incr_reg)
6687 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
6690 PUT_CODE (incr, NOTE);
6691 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
6692 NOTE_SOURCE_FILE (incr) = 0;
6695 if (regno >= FIRST_PSEUDO_REGISTER)
6697 /* Count an extra reference to the reg. When a reg is
6698 incremented, spilling it is worse, so we want to make
6699 that less likely. */
6700 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
6701 ? 1 : pbi->bb->frequency);
6703 /* Count the increment as a setting of the register,
6704 even though it isn't a SET in rtl. */
6705 REG_N_SETS (regno)++;
6709 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
6713 find_auto_inc (pbi, x, insn)
6714 struct propagate_block_info *pbi;
6718 rtx addr = XEXP (x, 0);
6719 HOST_WIDE_INT offset = 0;
6720 rtx set, y, incr, inc_val;
6722 int size = GET_MODE_SIZE (GET_MODE (x));
6724 if (GET_CODE (insn) == JUMP_INSN)
6727 /* Here we detect use of an index register which might be good for
6728 postincrement, postdecrement, preincrement, or predecrement. */
6730 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
6731 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
6733 if (GET_CODE (addr) != REG)
6736 regno = REGNO (addr);
6738 /* Is the next use an increment that might make auto-increment? */
6739 incr = pbi->reg_next_use[regno];
6740 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
6742 set = single_set (incr);
6743 if (set == 0 || GET_CODE (set) != SET)
6747 if (GET_CODE (y) != PLUS)
6750 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
6751 inc_val = XEXP (y, 1);
6752 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
6753 inc_val = XEXP (y, 0);
6757 if (GET_CODE (inc_val) == CONST_INT)
6759 if (HAVE_POST_INCREMENT
6760 && (INTVAL (inc_val) == size && offset == 0))
6761 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
6763 else if (HAVE_POST_DECREMENT
6764 && (INTVAL (inc_val) == -size && offset == 0))
6765 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
6767 else if (HAVE_PRE_INCREMENT
6768 && (INTVAL (inc_val) == size && offset == size))
6769 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
6771 else if (HAVE_PRE_DECREMENT
6772 && (INTVAL (inc_val) == -size && offset == -size))
6773 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
6775 else if (HAVE_POST_MODIFY_DISP && offset == 0)
6776 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6777 gen_rtx_PLUS (Pmode,
6780 insn, x, incr, addr);
6782 else if (GET_CODE (inc_val) == REG
6783 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
6787 if (HAVE_POST_MODIFY_REG && offset == 0)
6788 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
6789 gen_rtx_PLUS (Pmode,
6792 insn, x, incr, addr);
6796 #endif /* AUTO_INC_DEC */
6799 mark_used_reg (pbi, reg, cond, insn)
6800 struct propagate_block_info *pbi;
6802 rtx cond ATTRIBUTE_UNUSED;
6805 unsigned int regno_first, regno_last, i;
6806 int some_was_live, some_was_dead, some_not_set;
6808 regno_last = regno_first = REGNO (reg);
6809 if (regno_first < FIRST_PSEUDO_REGISTER)
6810 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
6812 /* Find out if any of this register is live after this instruction. */
6813 some_was_live = some_was_dead = 0;
6814 for (i = regno_first; i <= regno_last; ++i)
6816 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
6817 some_was_live |= needed_regno;
6818 some_was_dead |= ! needed_regno;
6821 /* Find out if any of the register was set this insn. */
6823 for (i = regno_first; i <= regno_last; ++i)
6824 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
6826 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
6828 /* Record where each reg is used, so when the reg is set we know
6829 the next insn that uses it. */
6830 pbi->reg_next_use[regno_first] = insn;
6833 if (pbi->flags & PROP_REG_INFO)
6835 if (regno_first < FIRST_PSEUDO_REGISTER)
6837 /* If this is a register we are going to try to eliminate,
6838 don't mark it live here. If we are successful in
6839 eliminating it, it need not be live unless it is used for
6840 pseudos, in which case it will have been set live when it
6841 was allocated to the pseudos. If the register will not
6842 be eliminated, reload will set it live at that point.
6844 Otherwise, record that this function uses this register. */
6845 /* ??? The PPC backend tries to "eliminate" on the pic
6846 register to itself. This should be fixed. In the mean
6847 time, hack around it. */
6849 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
6850 && (regno_first == FRAME_POINTER_REGNUM
6851 || regno_first == ARG_POINTER_REGNUM)))
6852 for (i = regno_first; i <= regno_last; ++i)
6853 regs_ever_live[i] = 1;
6857 /* Keep track of which basic block each reg appears in. */
6859 register int blocknum = pbi->bb->index;
6860 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
6861 REG_BASIC_BLOCK (regno_first) = blocknum;
6862 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
6863 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
6865 /* Count (weighted) number of uses of each reg. */
6866 REG_FREQ (regno_first)
6867 += (optimize_size || !pbi->bb->frequency ? 1 : pbi->bb->frequency);
6868 REG_N_REFS (regno_first)++;
6872 /* Record and count the insns in which a reg dies. If it is used in
6873 this insn and was dead below the insn then it dies in this insn.
6874 If it was set in this insn, we do not make a REG_DEAD note;
6875 likewise if we already made such a note. */
6876 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
6880 /* Check for the case where the register dying partially
6881 overlaps the register set by this insn. */
6882 if (regno_first != regno_last)
6883 for (i = regno_first; i <= regno_last; ++i)
6884 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
6886 /* If none of the words in X is needed, make a REG_DEAD note.
6887 Otherwise, we must make partial REG_DEAD notes. */
6888 if (! some_was_live)
6890 if ((pbi->flags & PROP_DEATH_NOTES)
6891 && ! find_regno_note (insn, REG_DEAD, regno_first))
6893 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
6895 if (pbi->flags & PROP_REG_INFO)
6896 REG_N_DEATHS (regno_first)++;
6900 /* Don't make a REG_DEAD note for a part of a register
6901 that is set in the insn. */
6902 for (i = regno_first; i <= regno_last; ++i)
6903 if (! REGNO_REG_SET_P (pbi->reg_live, i)
6904 && ! dead_or_set_regno_p (insn, i))
6906 = alloc_EXPR_LIST (REG_DEAD,
6907 gen_rtx_REG (reg_raw_mode[i], i),
6912 /* Mark the register as being live. */
6913 for (i = regno_first; i <= regno_last; ++i)
6915 SET_REGNO_REG_SET (pbi->reg_live, i);
6917 #ifdef HAVE_conditional_execution
6918 /* If this is a conditional use, record that fact. If it is later
6919 conditionally set, we'll know to kill the register. */
6920 if (cond != NULL_RTX)
6922 splay_tree_node node;
6923 struct reg_cond_life_info *rcli;
6928 node = splay_tree_lookup (pbi->reg_cond_dead, i);
6931 /* The register was unconditionally live previously.
6932 No need to do anything. */
6936 /* The register was conditionally live previously.
6937 Subtract the new life cond from the old death cond. */
6938 rcli = (struct reg_cond_life_info *) node->value;
6939 ncond = rcli->condition;
6940 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
6942 /* If the register is now unconditionally live,
6943 remove the entry in the splay_tree. */
6944 if (ncond == const0_rtx)
6945 splay_tree_remove (pbi->reg_cond_dead, i);
6948 rcli->condition = ncond;
6949 SET_REGNO_REG_SET (pbi->reg_cond_reg,
6950 REGNO (XEXP (cond, 0)));
6956 /* The register was not previously live at all. Record
6957 the condition under which it is still dead. */
6958 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
6959 rcli->condition = not_reg_cond (cond);
6960 rcli->stores = const0_rtx;
6961 rcli->orig_condition = const0_rtx;
6962 splay_tree_insert (pbi->reg_cond_dead, i,
6963 (splay_tree_value) rcli);
6965 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
6968 else if (some_was_live)
6970 /* The register may have been conditionally live previously, but
6971 is now unconditionally live. Remove it from the conditionally
6972 dead list, so that a conditional set won't cause us to think
6974 splay_tree_remove (pbi->reg_cond_dead, i);
6980 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
6981 This is done assuming the registers needed from X are those that
6982 have 1-bits in PBI->REG_LIVE.
6984 INSN is the containing instruction. If INSN is dead, this function
6988 mark_used_regs (pbi, x, cond, insn)
6989 struct propagate_block_info *pbi;
6992 register RTX_CODE code;
6994 int flags = pbi->flags;
6997 code = GET_CODE (x);
7017 /* If we are clobbering a MEM, mark any registers inside the address
7019 if (GET_CODE (XEXP (x, 0)) == MEM)
7020 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
7024 /* Don't bother watching stores to mems if this is not the
7025 final pass. We'll not be deleting dead stores this round. */
7026 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
7028 /* Invalidate the data for the last MEM stored, but only if MEM is
7029 something that can be stored into. */
7030 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
7031 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
7032 /* Needn't clear the memory set list. */
7036 rtx temp = pbi->mem_set_list;
7037 rtx prev = NULL_RTX;
7042 next = XEXP (temp, 1);
7043 if (anti_dependence (XEXP (temp, 0), x))
7045 /* Splice temp out of the list. */
7047 XEXP (prev, 1) = next;
7049 pbi->mem_set_list = next;
7050 free_EXPR_LIST_node (temp);
7051 pbi->mem_set_list_len--;
7059 /* If the memory reference had embedded side effects (autoincrement
7060 address modes. Then we may need to kill some entries on the
7063 invalidate_mems_from_autoinc (pbi, insn);
7067 if (flags & PROP_AUTOINC)
7068 find_auto_inc (pbi, x, insn);
7073 #ifdef CLASS_CANNOT_CHANGE_MODE
7074 if (GET_CODE (SUBREG_REG (x)) == REG
7075 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
7076 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
7077 GET_MODE (SUBREG_REG (x))))
7078 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
7081 /* While we're here, optimize this case. */
7083 if (GET_CODE (x) != REG)
7088 /* See a register other than being set => mark it as needed. */
7089 mark_used_reg (pbi, x, cond, insn);
7094 register rtx testreg = SET_DEST (x);
7097 /* If storing into MEM, don't show it as being used. But do
7098 show the address as being used. */
7099 if (GET_CODE (testreg) == MEM)
7102 if (flags & PROP_AUTOINC)
7103 find_auto_inc (pbi, testreg, insn);
7105 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
7106 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7110 /* Storing in STRICT_LOW_PART is like storing in a reg
7111 in that this SET might be dead, so ignore it in TESTREG.
7112 but in some other ways it is like using the reg.
7114 Storing in a SUBREG or a bit field is like storing the entire
7115 register in that if the register's value is not used
7116 then this SET is not needed. */
7117 while (GET_CODE (testreg) == STRICT_LOW_PART
7118 || GET_CODE (testreg) == ZERO_EXTRACT
7119 || GET_CODE (testreg) == SIGN_EXTRACT
7120 || GET_CODE (testreg) == SUBREG)
7122 #ifdef CLASS_CANNOT_CHANGE_MODE
7123 if (GET_CODE (testreg) == SUBREG
7124 && GET_CODE (SUBREG_REG (testreg)) == REG
7125 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
7126 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
7127 GET_MODE (testreg)))
7128 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
7131 /* Modifying a single register in an alternate mode
7132 does not use any of the old value. But these other
7133 ways of storing in a register do use the old value. */
7134 if (GET_CODE (testreg) == SUBREG
7135 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
7140 testreg = XEXP (testreg, 0);
7143 /* If this is a store into a register or group of registers,
7144 recursively scan the value being stored. */
7146 if ((GET_CODE (testreg) == PARALLEL
7147 && GET_MODE (testreg) == BLKmode)
7148 || (GET_CODE (testreg) == REG
7149 && (regno = REGNO (testreg),
7150 ! (regno == FRAME_POINTER_REGNUM
7151 && (! reload_completed || frame_pointer_needed)))
7152 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
7153 && ! (regno == HARD_FRAME_POINTER_REGNUM
7154 && (! reload_completed || frame_pointer_needed))
7156 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
7157 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
7162 mark_used_regs (pbi, SET_DEST (x), cond, insn);
7163 mark_used_regs (pbi, SET_SRC (x), cond, insn);
7170 case UNSPEC_VOLATILE:
7174 /* Traditional and volatile asm instructions must be considered to use
7175 and clobber all hard registers, all pseudo-registers and all of
7176 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
7178 Consider for instance a volatile asm that changes the fpu rounding
7179 mode. An insn should not be moved across this even if it only uses
7180 pseudo-regs because it might give an incorrectly rounded result.
7182 ?!? Unfortunately, marking all hard registers as live causes massive
7183 problems for the register allocator and marking all pseudos as live
7184 creates mountains of uninitialized variable warnings.
7186 So for now, just clear the memory set list and mark any regs
7187 we can find in ASM_OPERANDS as used. */
7188 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
7190 free_EXPR_LIST_list (&pbi->mem_set_list);
7191 pbi->mem_set_list_len = 0;
7194 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
7195 We can not just fall through here since then we would be confused
7196 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
7197 traditional asms unlike their normal usage. */
7198 if (code == ASM_OPERANDS)
7202 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
7203 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
7209 if (cond != NULL_RTX)
7212 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
7214 cond = COND_EXEC_TEST (x);
7215 x = COND_EXEC_CODE (x);
7219 /* We _do_not_ want to scan operands of phi nodes. Operands of
7220 a phi function are evaluated only when control reaches this
7221 block along a particular edge. Therefore, regs that appear
7222 as arguments to phi should not be added to the global live at
7230 /* Recursively scan the operands of this expression. */
7233 register const char *fmt = GET_RTX_FORMAT (code);
7236 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7240 /* Tail recursive case: save a function call level. */
7246 mark_used_regs (pbi, XEXP (x, i), cond, insn);
7248 else if (fmt[i] == 'E')
7251 for (j = 0; j < XVECLEN (x, i); j++)
7252 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
7261 try_pre_increment_1 (pbi, insn)
7262 struct propagate_block_info *pbi;
7265 /* Find the next use of this reg. If in same basic block,
7266 make it do pre-increment or pre-decrement if appropriate. */
7267 rtx x = single_set (insn);
7268 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
7269 * INTVAL (XEXP (SET_SRC (x), 1)));
7270 int regno = REGNO (SET_DEST (x));
7271 rtx y = pbi->reg_next_use[regno];
7273 && SET_DEST (x) != stack_pointer_rtx
7274 && BLOCK_NUM (y) == BLOCK_NUM (insn)
7275 /* Don't do this if the reg dies, or gets set in y; a standard addressing
7276 mode would be better. */
7277 && ! dead_or_set_p (y, SET_DEST (x))
7278 && try_pre_increment (y, SET_DEST (x), amount))
7280 /* We have found a suitable auto-increment and already changed
7281 insn Y to do it. So flush this increment instruction. */
7282 propagate_block_delete_insn (pbi->bb, insn);
7284 /* Count a reference to this reg for the increment insn we are
7285 deleting. When a reg is incremented, spilling it is worse,
7286 so we want to make that less likely. */
7287 if (regno >= FIRST_PSEUDO_REGISTER)
7289 REG_FREQ (regno) += (optimize_size || !pbi->bb->frequency
7290 ? 1 : pbi->bb->frequency);
7291 REG_N_SETS (regno)++;
7294 /* Flush any remembered memories depending on the value of
7295 the incremented register. */
7296 invalidate_mems_from_set (pbi, SET_DEST (x));
7303 /* Try to change INSN so that it does pre-increment or pre-decrement
7304 addressing on register REG in order to add AMOUNT to REG.
7305 AMOUNT is negative for pre-decrement.
7306 Returns 1 if the change could be made.
7307 This checks all about the validity of the result of modifying INSN. */
7310 try_pre_increment (insn, reg, amount)
7312 HOST_WIDE_INT amount;
7316 /* Nonzero if we can try to make a pre-increment or pre-decrement.
7317 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
7319 /* Nonzero if we can try to make a post-increment or post-decrement.
7320 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
7321 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
7322 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
7325 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
7328 /* From the sign of increment, see which possibilities are conceivable
7329 on this target machine. */
7330 if (HAVE_PRE_INCREMENT && amount > 0)
7332 if (HAVE_POST_INCREMENT && amount > 0)
7335 if (HAVE_PRE_DECREMENT && amount < 0)
7337 if (HAVE_POST_DECREMENT && amount < 0)
7340 if (! (pre_ok || post_ok))
7343 /* It is not safe to add a side effect to a jump insn
7344 because if the incremented register is spilled and must be reloaded
7345 there would be no way to store the incremented value back in memory. */
7347 if (GET_CODE (insn) == JUMP_INSN)
7352 use = find_use_as_address (PATTERN (insn), reg, 0);
7353 if (post_ok && (use == 0 || use == (rtx) 1))
7355 use = find_use_as_address (PATTERN (insn), reg, -amount);
7359 if (use == 0 || use == (rtx) 1)
7362 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
7365 /* See if this combination of instruction and addressing mode exists. */
7366 if (! validate_change (insn, &XEXP (use, 0),
7367 gen_rtx_fmt_e (amount > 0
7368 ? (do_post ? POST_INC : PRE_INC)
7369 : (do_post ? POST_DEC : PRE_DEC),
7373 /* Record that this insn now has an implicit side effect on X. */
7374 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
7378 #endif /* AUTO_INC_DEC */
7380 /* Find the place in the rtx X where REG is used as a memory address.
7381 Return the MEM rtx that so uses it.
7382 If PLUSCONST is nonzero, search instead for a memory address equivalent to
7383 (plus REG (const_int PLUSCONST)).
7385 If such an address does not appear, return 0.
7386 If REG appears more than once, or is used other than in such an address,
7390 find_use_as_address (x, reg, plusconst)
7393 HOST_WIDE_INT plusconst;
7395 enum rtx_code code = GET_CODE (x);
7396 const char *fmt = GET_RTX_FORMAT (code);
7398 register rtx value = 0;
7401 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
7404 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
7405 && XEXP (XEXP (x, 0), 0) == reg
7406 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
7407 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
7410 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
7412 /* If REG occurs inside a MEM used in a bit-field reference,
7413 that is unacceptable. */
7414 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
7415 return (rtx) (HOST_WIDE_INT) 1;
7419 return (rtx) (HOST_WIDE_INT) 1;
7421 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7425 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
7429 return (rtx) (HOST_WIDE_INT) 1;
7431 else if (fmt[i] == 'E')
7434 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7436 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
7440 return (rtx) (HOST_WIDE_INT) 1;
7448 /* Write information about registers and basic blocks into FILE.
7449 This is part of making a debugging dump. */
7452 dump_regset (r, outf)
7459 fputs (" (nil)", outf);
7463 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
7465 fprintf (outf, " %d", i);
7466 if (i < FIRST_PSEUDO_REGISTER)
7467 fprintf (outf, " [%s]",
7472 /* Print a human-reaable representation of R on the standard error
7473 stream. This function is designed to be used from within the
7480 dump_regset (r, stderr);
7481 putc ('\n', stderr);
7485 dump_flow_info (file)
7489 static const char * const reg_class_names[] = REG_CLASS_NAMES;
7491 fprintf (file, "%d registers.\n", max_regno);
7492 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
7495 enum reg_class class, altclass;
7496 fprintf (file, "\nRegister %d used %d times across %d insns",
7497 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
7498 if (REG_BASIC_BLOCK (i) >= 0)
7499 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
7501 fprintf (file, "; set %d time%s", REG_N_SETS (i),
7502 (REG_N_SETS (i) == 1) ? "" : "s");
7503 if (REG_USERVAR_P (regno_reg_rtx[i]))
7504 fprintf (file, "; user var");
7505 if (REG_N_DEATHS (i) != 1)
7506 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
7507 if (REG_N_CALLS_CROSSED (i) == 1)
7508 fprintf (file, "; crosses 1 call");
7509 else if (REG_N_CALLS_CROSSED (i))
7510 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
7511 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
7512 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
7513 class = reg_preferred_class (i);
7514 altclass = reg_alternate_class (i);
7515 if (class != GENERAL_REGS || altclass != ALL_REGS)
7517 if (altclass == ALL_REGS || class == ALL_REGS)
7518 fprintf (file, "; pref %s", reg_class_names[(int) class]);
7519 else if (altclass == NO_REGS)
7520 fprintf (file, "; %s or none", reg_class_names[(int) class]);
7522 fprintf (file, "; pref %s, else %s",
7523 reg_class_names[(int) class],
7524 reg_class_names[(int) altclass]);
7526 if (REG_POINTER (regno_reg_rtx[i]))
7527 fprintf (file, "; pointer");
7528 fprintf (file, ".\n");
7531 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
7532 for (i = 0; i < n_basic_blocks; i++)
7534 register basic_block bb = BASIC_BLOCK (i);
7537 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count ",
7538 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth);
7539 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7540 fprintf (file, ", freq %i.\n", bb->frequency);
7542 fprintf (file, "Predecessors: ");
7543 for (e = bb->pred; e; e = e->pred_next)
7544 dump_edge_info (file, e, 0);
7546 fprintf (file, "\nSuccessors: ");
7547 for (e = bb->succ; e; e = e->succ_next)
7548 dump_edge_info (file, e, 1);
7550 fprintf (file, "\nRegisters live at start:");
7551 dump_regset (bb->global_live_at_start, file);
7553 fprintf (file, "\nRegisters live at end:");
7554 dump_regset (bb->global_live_at_end, file);
7565 dump_flow_info (stderr);
7569 dump_edge_info (file, e, do_succ)
7574 basic_block side = (do_succ ? e->dest : e->src);
7576 if (side == ENTRY_BLOCK_PTR)
7577 fputs (" ENTRY", file);
7578 else if (side == EXIT_BLOCK_PTR)
7579 fputs (" EXIT", file);
7581 fprintf (file, " %d", side->index);
7584 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
7588 fprintf (file, " count:");
7589 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) e->count);
7594 static const char * const bitnames[] = {
7595 "fallthru", "crit", "ab", "abcall", "eh", "fake"
7598 int i, flags = e->flags;
7602 for (i = 0; flags; i++)
7603 if (flags & (1 << i))
7609 if (i < (int) ARRAY_SIZE (bitnames))
7610 fputs (bitnames[i], file);
7612 fprintf (file, "%d", i);
7619 /* Print out one basic block with live information at start and end. */
7630 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
7631 bb->index, bb->loop_depth);
7632 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
7635 fputs (";; Predecessors: ", outf);
7636 for (e = bb->pred; e; e = e->pred_next)
7637 dump_edge_info (outf, e, 0);
7640 fputs (";; Registers live at start:", outf);
7641 dump_regset (bb->global_live_at_start, outf);
7644 for (insn = bb->head, last = NEXT_INSN (bb->end);
7646 insn = NEXT_INSN (insn))
7647 print_rtl_single (outf, insn);
7649 fputs (";; Registers live at end:", outf);
7650 dump_regset (bb->global_live_at_end, outf);
7653 fputs (";; Successors: ", outf);
7654 for (e = bb->succ; e; e = e->succ_next)
7655 dump_edge_info (outf, e, 1);
7663 dump_bb (bb, stderr);
7670 dump_bb (BASIC_BLOCK (n), stderr);
7673 /* Like print_rtl, but also print out live information for the start of each
7677 print_rtl_with_bb (outf, rtx_first)
7681 register rtx tmp_rtx;
7684 fprintf (outf, "(nil)\n");
7688 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
7689 int max_uid = get_max_uid ();
7690 basic_block *start = (basic_block *)
7691 xcalloc (max_uid, sizeof (basic_block));
7692 basic_block *end = (basic_block *)
7693 xcalloc (max_uid, sizeof (basic_block));
7694 enum bb_state *in_bb_p = (enum bb_state *)
7695 xcalloc (max_uid, sizeof (enum bb_state));
7697 for (i = n_basic_blocks - 1; i >= 0; i--)
7699 basic_block bb = BASIC_BLOCK (i);
7702 start[INSN_UID (bb->head)] = bb;
7703 end[INSN_UID (bb->end)] = bb;
7704 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
7706 enum bb_state state = IN_MULTIPLE_BB;
7707 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
7709 in_bb_p[INSN_UID (x)] = state;
7716 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
7721 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
7723 fprintf (outf, ";; Start of basic block %d, registers live:",
7725 dump_regset (bb->global_live_at_start, outf);
7729 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
7730 && GET_CODE (tmp_rtx) != NOTE
7731 && GET_CODE (tmp_rtx) != BARRIER)
7732 fprintf (outf, ";; Insn is not within a basic block\n");
7733 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
7734 fprintf (outf, ";; Insn is in multiple basic blocks\n");
7736 did_output = print_rtl_single (outf, tmp_rtx);
7738 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
7740 fprintf (outf, ";; End of basic block %d, registers live:\n",
7742 dump_regset (bb->global_live_at_end, outf);
7755 if (current_function_epilogue_delay_list != 0)
7757 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
7758 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
7759 tmp_rtx = XEXP (tmp_rtx, 1))
7760 print_rtl_single (outf, XEXP (tmp_rtx, 0));
7764 /* Dump the rtl into the current debugging dump file, then abort. */
7767 print_rtl_and_abort_fcn (file, line, function)
7770 const char *function;
7774 print_rtl_with_bb (rtl_dump_file, get_insns ());
7775 fclose (rtl_dump_file);
7778 fancy_abort (file, line, function);
7781 /* Recompute register set/reference counts immediately prior to register
7784 This avoids problems with set/reference counts changing to/from values
7785 which have special meanings to the register allocators.
7787 Additionally, the reference counts are the primary component used by the
7788 register allocators to prioritize pseudos for allocation to hard regs.
7789 More accurate reference counts generally lead to better register allocation.
7791 F is the first insn to be scanned.
7793 LOOP_STEP denotes how much loop_depth should be incremented per
7794 loop nesting level in order to increase the ref count more for
7795 references in a loop.
7797 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
7798 possibly other information which is used by the register allocators. */
7801 recompute_reg_usage (f, loop_step)
7802 rtx f ATTRIBUTE_UNUSED;
7803 int loop_step ATTRIBUTE_UNUSED;
7805 allocate_reg_life_data ();
7806 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
7809 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
7810 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
7811 of the number of registers that died. */
7814 count_or_remove_death_notes (blocks, kill)
7820 for (i = n_basic_blocks - 1; i >= 0; --i)
7825 if (blocks && ! TEST_BIT (blocks, i))
7828 bb = BASIC_BLOCK (i);
7830 for (insn = bb->head;; insn = NEXT_INSN (insn))
7834 rtx *pprev = ®_NOTES (insn);
7839 switch (REG_NOTE_KIND (link))
7842 if (GET_CODE (XEXP (link, 0)) == REG)
7844 rtx reg = XEXP (link, 0);
7847 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
7850 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
7858 rtx next = XEXP (link, 1);
7859 free_EXPR_LIST_node (link);
7860 *pprev = link = next;
7866 pprev = &XEXP (link, 1);
7873 if (insn == bb->end)
7882 /* Update insns block within BB. */
7885 update_bb_for_insn (bb)
7890 if (! basic_block_for_insn)
7893 for (insn = bb->head; ; insn = NEXT_INSN (insn))
7895 set_block_for_insn (insn, bb);
7897 if (insn == bb->end)
7903 /* Record INSN's block as BB. */
7906 set_block_for_insn (insn, bb)
7910 size_t uid = INSN_UID (insn);
7911 if (uid >= basic_block_for_insn->num_elements)
7915 /* Add one-eighth the size so we don't keep calling xrealloc. */
7916 new_size = uid + (uid + 7) / 8;
7918 VARRAY_GROW (basic_block_for_insn, new_size);
7920 VARRAY_BB (basic_block_for_insn, uid) = bb;
7923 /* When a new insn has been inserted into an existing block, it will
7924 sometimes emit more than a single insn. This routine will set the
7925 block number for the specified insn, and look backwards in the insn
7926 chain to see if there are any other uninitialized insns immediately
7927 previous to this one, and set the block number for them too. */
7930 set_block_for_new_insns (insn, bb)
7934 set_block_for_insn (insn, bb);
7936 /* Scan the previous instructions setting the block number until we find
7937 an instruction that has the block number set, or we find a note
7939 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
7941 if (GET_CODE (insn) == NOTE)
7943 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
7944 || BLOCK_FOR_INSN (insn) == 0)
7945 set_block_for_insn (insn, bb);
7951 /* Verify the CFG consistency. This function check some CFG invariants and
7952 aborts when something is wrong. Hope that this function will help to
7953 convert many optimization passes to preserve CFG consistent.
7955 Currently it does following checks:
7957 - test head/end pointers
7958 - overlapping of basic blocks
7959 - edge list corectness
7960 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
7961 - tails of basic blocks (ensure that boundary is necesary)
7962 - scans body of the basic block for JUMP_INSN, CODE_LABEL
7963 and NOTE_INSN_BASIC_BLOCK
7964 - check that all insns are in the basic blocks
7965 (except the switch handling code, barriers and notes)
7966 - check that all returns are followed by barriers
7968 In future it can be extended check a lot of other stuff as well
7969 (reachability of basic blocks, life information, etc. etc.). */
7974 const int max_uid = get_max_uid ();
7975 const rtx rtx_first = get_insns ();
7976 rtx last_head = get_last_insn ();
7977 basic_block *bb_info;
7979 int i, last_bb_num_seen, num_bb_notes, err = 0;
7981 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
7983 for (i = n_basic_blocks - 1; i >= 0; i--)
7985 basic_block bb = BASIC_BLOCK (i);
7986 rtx head = bb->head;
7989 /* Verify the end of the basic block is in the INSN chain. */
7990 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
7995 error ("End insn %d for block %d not found in the insn stream.",
7996 INSN_UID (end), bb->index);
8000 /* Work backwards from the end to the head of the basic block
8001 to verify the head is in the RTL chain. */
8002 for (; x != NULL_RTX; x = PREV_INSN (x))
8004 /* While walking over the insn chain, verify insns appear
8005 in only one basic block and initialize the BB_INFO array
8006 used by other passes. */
8007 if (bb_info[INSN_UID (x)] != NULL)
8009 error ("Insn %d is in multiple basic blocks (%d and %d)",
8010 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
8013 bb_info[INSN_UID (x)] = bb;
8020 error ("Head insn %d for block %d not found in the insn stream.",
8021 INSN_UID (head), bb->index);
8028 /* Now check the basic blocks (boundaries etc.) */
8029 for (i = n_basic_blocks - 1; i >= 0; i--)
8031 basic_block bb = BASIC_BLOCK (i);
8032 /* Check corectness of edge lists */
8038 if ((e->flags & EDGE_FALLTHRU)
8039 && e->src != ENTRY_BLOCK_PTR
8040 && e->dest != EXIT_BLOCK_PTR
8041 && (e->src->index + 1 != e->dest->index
8042 || !can_fallthru (e->src, e->dest)))
8044 error ("verify_flow_info: Incorrect fallthru edge %i->%i",
8045 e->src->index, e->dest->index);
8051 error ("verify_flow_info: Basic block %d succ edge is corrupted",
8053 fprintf (stderr, "Predecessor: ");
8054 dump_edge_info (stderr, e, 0);
8055 fprintf (stderr, "\nSuccessor: ");
8056 dump_edge_info (stderr, e, 1);
8057 fprintf (stderr, "\n");
8060 if (e->dest != EXIT_BLOCK_PTR)
8062 edge e2 = e->dest->pred;
8063 while (e2 && e2 != e)
8067 error ("Basic block %i edge lists are corrupted", bb->index);
8079 error ("Basic block %d pred edge is corrupted", bb->index);
8080 fputs ("Predecessor: ", stderr);
8081 dump_edge_info (stderr, e, 0);
8082 fputs ("\nSuccessor: ", stderr);
8083 dump_edge_info (stderr, e, 1);
8084 fputc ('\n', stderr);
8087 if (e->src != ENTRY_BLOCK_PTR)
8089 edge e2 = e->src->succ;
8090 while (e2 && e2 != e)
8094 error ("Basic block %i edge lists are corrupted", bb->index);
8101 /* OK pointers are correct. Now check the header of basic
8102 block. It ought to contain optional CODE_LABEL followed
8103 by NOTE_BASIC_BLOCK. */
8105 if (GET_CODE (x) == CODE_LABEL)
8109 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
8115 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
8117 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
8124 /* Do checks for empty blocks here */
8131 if (NOTE_INSN_BASIC_BLOCK_P (x))
8133 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
8134 INSN_UID (x), bb->index);
8141 if (GET_CODE (x) == JUMP_INSN
8142 || GET_CODE (x) == CODE_LABEL
8143 || GET_CODE (x) == BARRIER)
8145 error ("In basic block %d:", bb->index);
8146 fatal_insn ("Flow control insn inside a basic block", x);
8154 last_bb_num_seen = -1;
8159 if (NOTE_INSN_BASIC_BLOCK_P (x))
8161 basic_block bb = NOTE_BASIC_BLOCK (x);
8163 if (bb->index != last_bb_num_seen + 1)
8164 /* Basic blocks not numbered consecutively. */
8167 last_bb_num_seen = bb->index;
8170 if (!bb_info[INSN_UID (x)])
8172 switch (GET_CODE (x))
8179 /* An addr_vec is placed outside any block block. */
8181 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
8182 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
8183 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
8188 /* But in any case, non-deletable labels can appear anywhere. */
8192 fatal_insn ("Insn outside basic block", x);
8197 && GET_CODE (x) == JUMP_INSN
8198 && returnjump_p (x) && ! condjump_p (x)
8199 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
8200 fatal_insn ("Return not followed by barrier", x);
8205 if (num_bb_notes != n_basic_blocks)
8207 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
8208 num_bb_notes, n_basic_blocks);
8217 /* Functions to access an edge list with a vector representation.
8218 Enough data is kept such that given an index number, the
8219 pred and succ that edge represents can be determined, or
8220 given a pred and a succ, its index number can be returned.
8221 This allows algorithms which consume a lot of memory to
8222 represent the normally full matrix of edge (pred,succ) with a
8223 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
8224 wasted space in the client code due to sparse flow graphs. */
8226 /* This functions initializes the edge list. Basically the entire
8227 flowgraph is processed, and all edges are assigned a number,
8228 and the data structure is filled in. */
8233 struct edge_list *elist;
8239 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
8243 /* Determine the number of edges in the flow graph by counting successor
8244 edges on each basic block. */
8245 for (x = 0; x < n_basic_blocks; x++)
8247 basic_block bb = BASIC_BLOCK (x);
8249 for (e = bb->succ; e; e = e->succ_next)
8252 /* Don't forget successors of the entry block. */
8253 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8256 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
8257 elist->num_blocks = block_count;
8258 elist->num_edges = num_edges;
8259 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
8263 /* Follow successors of the entry block, and register these edges. */
8264 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8266 elist->index_to_edge[num_edges] = e;
8270 for (x = 0; x < n_basic_blocks; x++)
8272 basic_block bb = BASIC_BLOCK (x);
8274 /* Follow all successors of blocks, and register these edges. */
8275 for (e = bb->succ; e; e = e->succ_next)
8277 elist->index_to_edge[num_edges] = e;
8284 /* This function free's memory associated with an edge list. */
8287 free_edge_list (elist)
8288 struct edge_list *elist;
8292 free (elist->index_to_edge);
8297 /* This function provides debug output showing an edge list. */
8300 print_edge_list (f, elist)
8302 struct edge_list *elist;
8305 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
8306 elist->num_blocks - 2, elist->num_edges);
8308 for (x = 0; x < elist->num_edges; x++)
8310 fprintf (f, " %-4d - edge(", x);
8311 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
8312 fprintf (f, "entry,");
8314 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
8316 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
8317 fprintf (f, "exit)\n");
8319 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
8323 /* This function provides an internal consistency check of an edge list,
8324 verifying that all edges are present, and that there are no
8328 verify_edge_list (f, elist)
8330 struct edge_list *elist;
8332 int x, pred, succ, index;
8335 for (x = 0; x < n_basic_blocks; x++)
8337 basic_block bb = BASIC_BLOCK (x);
8339 for (e = bb->succ; e; e = e->succ_next)
8341 pred = e->src->index;
8342 succ = e->dest->index;
8343 index = EDGE_INDEX (elist, e->src, e->dest);
8344 if (index == EDGE_INDEX_NO_EDGE)
8346 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8349 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8350 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8351 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8352 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8353 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8354 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8357 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
8359 pred = e->src->index;
8360 succ = e->dest->index;
8361 index = EDGE_INDEX (elist, e->src, e->dest);
8362 if (index == EDGE_INDEX_NO_EDGE)
8364 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
8367 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
8368 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
8369 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
8370 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
8371 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
8372 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
8374 /* We've verified that all the edges are in the list, no lets make sure
8375 there are no spurious edges in the list. */
8377 for (pred = 0; pred < n_basic_blocks; pred++)
8378 for (succ = 0; succ < n_basic_blocks; succ++)
8380 basic_block p = BASIC_BLOCK (pred);
8381 basic_block s = BASIC_BLOCK (succ);
8385 for (e = p->succ; e; e = e->succ_next)
8391 for (e = s->pred; e; e = e->pred_next)
8397 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8398 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8399 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
8401 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
8402 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8403 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
8404 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8405 BASIC_BLOCK (succ)));
8407 for (succ = 0; succ < n_basic_blocks; succ++)
8409 basic_block p = ENTRY_BLOCK_PTR;
8410 basic_block s = BASIC_BLOCK (succ);
8414 for (e = p->succ; e; e = e->succ_next)
8420 for (e = s->pred; e; e = e->pred_next)
8426 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8427 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8428 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
8430 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
8431 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8432 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
8433 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
8434 BASIC_BLOCK (succ)));
8436 for (pred = 0; pred < n_basic_blocks; pred++)
8438 basic_block p = BASIC_BLOCK (pred);
8439 basic_block s = EXIT_BLOCK_PTR;
8443 for (e = p->succ; e; e = e->succ_next)
8449 for (e = s->pred; e; e = e->pred_next)
8455 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8456 == EDGE_INDEX_NO_EDGE && found_edge != 0)
8457 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
8459 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
8460 != EDGE_INDEX_NO_EDGE && found_edge == 0)
8461 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
8462 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
8467 /* This routine will determine what, if any, edge there is between
8468 a specified predecessor and successor. */
8471 find_edge_index (edge_list, pred, succ)
8472 struct edge_list *edge_list;
8473 basic_block pred, succ;
8476 for (x = 0; x < NUM_EDGES (edge_list); x++)
8478 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
8479 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
8482 return (EDGE_INDEX_NO_EDGE);
8485 /* This function will remove an edge from the flow graph. */
8491 edge last_pred = NULL;
8492 edge last_succ = NULL;
8494 basic_block src, dest;
8497 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
8503 last_succ->succ_next = e->succ_next;
8505 src->succ = e->succ_next;
8507 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
8513 last_pred->pred_next = e->pred_next;
8515 dest->pred = e->pred_next;
8521 /* This routine will remove any fake successor edges for a basic block.
8522 When the edge is removed, it is also removed from whatever predecessor
8526 remove_fake_successors (bb)
8530 for (e = bb->succ; e;)
8534 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
8539 /* This routine will remove all fake edges from the flow graph. If
8540 we remove all fake successors, it will automatically remove all
8541 fake predecessors. */
8544 remove_fake_edges ()
8548 for (x = 0; x < n_basic_blocks; x++)
8549 remove_fake_successors (BASIC_BLOCK (x));
8551 /* We've handled all successors except the entry block's. */
8552 remove_fake_successors (ENTRY_BLOCK_PTR);
8555 /* This function will add a fake edge between any block which has no
8556 successors, and the exit block. Some data flow equations require these
8560 add_noreturn_fake_exit_edges ()
8564 for (x = 0; x < n_basic_blocks; x++)
8565 if (BASIC_BLOCK (x)->succ == NULL)
8566 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
8569 /* This function adds a fake edge between any infinite loops to the
8570 exit block. Some optimizations require a path from each node to
8573 See also Morgan, Figure 3.10, pp. 82-83.
8575 The current implementation is ugly, not attempting to minimize the
8576 number of inserted fake edges. To reduce the number of fake edges
8577 to insert, add fake edges from _innermost_ loops containing only
8578 nodes not reachable from the exit block. */
8581 connect_infinite_loops_to_exit ()
8583 basic_block unvisited_block;
8585 /* Perform depth-first search in the reverse graph to find nodes
8586 reachable from the exit block. */
8587 struct depth_first_search_dsS dfs_ds;
8589 flow_dfs_compute_reverse_init (&dfs_ds);
8590 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
8592 /* Repeatedly add fake edges, updating the unreachable nodes. */
8595 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
8596 if (!unvisited_block)
8598 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
8599 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
8602 flow_dfs_compute_reverse_finish (&dfs_ds);
8607 /* Redirect an edge's successor from one block to another. */
8610 redirect_edge_succ (e, new_succ)
8612 basic_block new_succ;
8616 /* Disconnect the edge from the old successor block. */
8617 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
8619 *pe = (*pe)->pred_next;
8621 /* Reconnect the edge to the new successor block. */
8622 e->pred_next = new_succ->pred;
8627 /* Redirect an edge's predecessor from one block to another. */
8630 redirect_edge_pred (e, new_pred)
8632 basic_block new_pred;
8636 /* Disconnect the edge from the old predecessor block. */
8637 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
8639 *pe = (*pe)->succ_next;
8641 /* Reconnect the edge to the new predecessor block. */
8642 e->succ_next = new_pred->succ;
8647 /* Dump the list of basic blocks in the bitmap NODES. */
8650 flow_nodes_print (str, nodes, file)
8652 const sbitmap nodes;
8660 fprintf (file, "%s { ", str);
8661 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
8662 fputs ("}\n", file);
8666 /* Dump the list of edges in the array EDGE_LIST. */
8669 flow_edge_list_print (str, edge_list, num_edges, file)
8671 const edge *edge_list;
8680 fprintf (file, "%s { ", str);
8681 for (i = 0; i < num_edges; i++)
8682 fprintf (file, "%d->%d ", edge_list[i]->src->index,
8683 edge_list[i]->dest->index);
8684 fputs ("}\n", file);
8688 /* Dump loop related CFG information. */
8691 flow_loops_cfg_dump (loops, file)
8692 const struct loops *loops;
8697 if (! loops->num || ! file || ! loops->cfg.dom)
8700 for (i = 0; i < n_basic_blocks; i++)
8704 fprintf (file, ";; %d succs { ", i);
8705 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
8706 fprintf (file, "%d ", succ->dest->index);
8707 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
8710 /* Dump the DFS node order. */
8711 if (loops->cfg.dfs_order)
8713 fputs (";; DFS order: ", file);
8714 for (i = 0; i < n_basic_blocks; i++)
8715 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
8718 /* Dump the reverse completion node order. */
8719 if (loops->cfg.rc_order)
8721 fputs (";; RC order: ", file);
8722 for (i = 0; i < n_basic_blocks; i++)
8723 fprintf (file, "%d ", loops->cfg.rc_order[i]);
8728 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
8731 flow_loop_nested_p (outer, loop)
8735 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
8739 /* Dump the loop information specified by LOOP to the stream FILE
8740 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8742 flow_loop_dump (loop, file, loop_dump_aux, verbose)
8743 const struct loop *loop;
8745 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8748 if (! loop || ! loop->header)
8751 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
8752 loop->num, INSN_UID (loop->first->head),
8753 INSN_UID (loop->last->end),
8754 loop->shared ? " shared" : "",
8755 loop->invalid ? " invalid" : "");
8756 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
8757 loop->header->index, loop->latch->index,
8758 loop->pre_header ? loop->pre_header->index : -1,
8759 loop->first->index, loop->last->index);
8760 fprintf (file, ";; depth %d, level %d, outer %ld\n",
8761 loop->depth, loop->level,
8762 (long) (loop->outer ? loop->outer->num : -1));
8764 if (loop->pre_header_edges)
8765 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
8766 loop->num_pre_header_edges, file);
8767 flow_edge_list_print (";; entry edges", loop->entry_edges,
8768 loop->num_entries, file);
8769 fprintf (file, ";; %d", loop->num_nodes);
8770 flow_nodes_print (" nodes", loop->nodes, file);
8771 flow_edge_list_print (";; exit edges", loop->exit_edges,
8772 loop->num_exits, file);
8773 if (loop->exits_doms)
8774 flow_nodes_print (";; exit doms", loop->exits_doms, file);
8776 loop_dump_aux (loop, file, verbose);
8780 /* Dump the loop information specified by LOOPS to the stream FILE,
8781 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
8783 flow_loops_dump (loops, file, loop_dump_aux, verbose)
8784 const struct loops *loops;
8786 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
8792 num_loops = loops->num;
8793 if (! num_loops || ! file)
8796 fprintf (file, ";; %d loops found, %d levels\n",
8797 num_loops, loops->levels);
8799 for (i = 0; i < num_loops; i++)
8801 struct loop *loop = &loops->array[i];
8803 flow_loop_dump (loop, file, loop_dump_aux, verbose);
8809 for (j = 0; j < i; j++)
8811 struct loop *oloop = &loops->array[j];
8813 if (loop->header == oloop->header)
8818 smaller = loop->num_nodes < oloop->num_nodes;
8820 /* If the union of LOOP and OLOOP is different than
8821 the larger of LOOP and OLOOP then LOOP and OLOOP
8822 must be disjoint. */
8823 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
8824 smaller ? oloop : loop);
8826 ";; loop header %d shared by loops %d, %d %s\n",
8827 loop->header->index, i, j,
8828 disjoint ? "disjoint" : "nested");
8835 flow_loops_cfg_dump (loops, file);
8839 /* Free all the memory allocated for LOOPS. */
8842 flow_loops_free (loops)
8843 struct loops *loops;
8852 /* Free the loop descriptors. */
8853 for (i = 0; i < loops->num; i++)
8855 struct loop *loop = &loops->array[i];
8857 if (loop->pre_header_edges)
8858 free (loop->pre_header_edges);
8860 sbitmap_free (loop->nodes);
8861 if (loop->entry_edges)
8862 free (loop->entry_edges);
8863 if (loop->exit_edges)
8864 free (loop->exit_edges);
8865 if (loop->exits_doms)
8866 sbitmap_free (loop->exits_doms);
8868 free (loops->array);
8869 loops->array = NULL;
8872 sbitmap_vector_free (loops->cfg.dom);
8873 if (loops->cfg.dfs_order)
8874 free (loops->cfg.dfs_order);
8876 if (loops->shared_headers)
8877 sbitmap_free (loops->shared_headers);
8882 /* Find the entry edges into the loop with header HEADER and nodes
8883 NODES and store in ENTRY_EDGES array. Return the number of entry
8884 edges from the loop. */
8887 flow_loop_entry_edges_find (header, nodes, entry_edges)
8889 const sbitmap nodes;
8895 *entry_edges = NULL;
8898 for (e = header->pred; e; e = e->pred_next)
8900 basic_block src = e->src;
8902 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
8909 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
8912 for (e = header->pred; e; e = e->pred_next)
8914 basic_block src = e->src;
8916 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
8917 (*entry_edges)[num_entries++] = e;
8924 /* Find the exit edges from the loop using the bitmap of loop nodes
8925 NODES and store in EXIT_EDGES array. Return the number of
8926 exit edges from the loop. */
8929 flow_loop_exit_edges_find (nodes, exit_edges)
8930 const sbitmap nodes;
8939 /* Check all nodes within the loop to see if there are any
8940 successors not in the loop. Note that a node may have multiple
8941 exiting edges ????? A node can have one jumping edge and one fallthru
8942 edge so only one of these can exit the loop. */
8944 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
8945 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
8947 basic_block dest = e->dest;
8949 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
8957 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
8959 /* Store all exiting edges into an array. */
8961 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
8962 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
8964 basic_block dest = e->dest;
8966 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
8967 (*exit_edges)[num_exits++] = e;
8975 /* Find the nodes contained within the loop with header HEADER and
8976 latch LATCH and store in NODES. Return the number of nodes within
8980 flow_loop_nodes_find (header, latch, nodes)
8989 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
8992 /* Start with only the loop header in the set of loop nodes. */
8993 sbitmap_zero (nodes);
8994 SET_BIT (nodes, header->index);
8996 header->loop_depth++;
8998 /* Push the loop latch on to the stack. */
8999 if (! TEST_BIT (nodes, latch->index))
9001 SET_BIT (nodes, latch->index);
9002 latch->loop_depth++;
9004 stack[sp++] = latch;
9013 for (e = node->pred; e; e = e->pred_next)
9015 basic_block ancestor = e->src;
9017 /* If each ancestor not marked as part of loop, add to set of
9018 loop nodes and push on to stack. */
9019 if (ancestor != ENTRY_BLOCK_PTR
9020 && ! TEST_BIT (nodes, ancestor->index))
9022 SET_BIT (nodes, ancestor->index);
9023 ancestor->loop_depth++;
9025 stack[sp++] = ancestor;
9033 /* Compute the depth first search order and store in the array
9034 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
9035 RC_ORDER is non-zero, return the reverse completion number for each
9036 node. Returns the number of nodes visited. A depth first search
9037 tries to get as far away from the starting point as quickly as
9041 flow_depth_first_order_compute (dfs_order, rc_order)
9048 int rcnum = n_basic_blocks - 1;
9051 /* Allocate stack for back-tracking up CFG. */
9052 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
9055 /* Allocate bitmap to track nodes that have been visited. */
9056 visited = sbitmap_alloc (n_basic_blocks);
9058 /* None of the nodes in the CFG have been visited yet. */
9059 sbitmap_zero (visited);
9061 /* Push the first edge on to the stack. */
9062 stack[sp++] = ENTRY_BLOCK_PTR->succ;
9070 /* Look at the edge on the top of the stack. */
9075 /* Check if the edge destination has been visited yet. */
9076 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
9078 /* Mark that we have visited the destination. */
9079 SET_BIT (visited, dest->index);
9082 dfs_order[dfsnum++] = dest->index;
9086 /* Since the DEST node has been visited for the first
9087 time, check its successors. */
9088 stack[sp++] = dest->succ;
9092 /* There are no successors for the DEST node so assign
9093 its reverse completion number. */
9095 rc_order[rcnum--] = dest->index;
9100 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
9102 /* There are no more successors for the SRC node
9103 so assign its reverse completion number. */
9105 rc_order[rcnum--] = src->index;
9109 stack[sp - 1] = e->succ_next;
9116 sbitmap_free (visited);
9118 /* The number of nodes visited should not be greater than
9120 if (dfsnum > n_basic_blocks)
9123 /* There are some nodes left in the CFG that are unreachable. */
9124 if (dfsnum < n_basic_blocks)
9129 /* Compute the depth first search order on the _reverse_ graph and
9130 store in the array DFS_ORDER, marking the nodes visited in VISITED.
9131 Returns the number of nodes visited.
9133 The computation is split into three pieces:
9135 flow_dfs_compute_reverse_init () creates the necessary data
9138 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
9139 structures. The block will start the search.
9141 flow_dfs_compute_reverse_execute () continues (or starts) the
9142 search using the block on the top of the stack, stopping when the
9145 flow_dfs_compute_reverse_finish () destroys the necessary data
9148 Thus, the user will probably call ..._init(), call ..._add_bb() to
9149 add a beginning basic block to the stack, call ..._execute(),
9150 possibly add another bb to the stack and again call ..._execute(),
9151 ..., and finally call _finish(). */
9153 /* Initialize the data structures used for depth-first search on the
9154 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
9155 added to the basic block stack. DATA is the current depth-first
9156 search context. If INITIALIZE_STACK is non-zero, there is an
9157 element on the stack. */
9160 flow_dfs_compute_reverse_init (data)
9161 depth_first_search_ds data;
9163 /* Allocate stack for back-tracking up CFG. */
9165 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
9166 * sizeof (basic_block));
9169 /* Allocate bitmap to track nodes that have been visited. */
9170 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
9172 /* None of the nodes in the CFG have been visited yet. */
9173 sbitmap_zero (data->visited_blocks);
9178 /* Add the specified basic block to the top of the dfs data
9179 structures. When the search continues, it will start at the
9183 flow_dfs_compute_reverse_add_bb (data, bb)
9184 depth_first_search_ds data;
9187 data->stack[data->sp++] = bb;
9191 /* Continue the depth-first search through the reverse graph starting
9192 with the block at the stack's top and ending when the stack is
9193 empty. Visited nodes are marked. Returns an unvisited basic
9194 block, or NULL if there is none available. */
9197 flow_dfs_compute_reverse_execute (data)
9198 depth_first_search_ds data;
9204 while (data->sp > 0)
9206 bb = data->stack[--data->sp];
9208 /* Mark that we have visited this node. */
9209 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
9211 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
9213 /* Perform depth-first search on adjacent vertices. */
9214 for (e = bb->pred; e; e = e->pred_next)
9215 flow_dfs_compute_reverse_add_bb (data, e->src);
9219 /* Determine if there are unvisited basic blocks. */
9220 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
9221 if (!TEST_BIT (data->visited_blocks, i))
9222 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
9226 /* Destroy the data structures needed for depth-first search on the
9230 flow_dfs_compute_reverse_finish (data)
9231 depth_first_search_ds data;
9234 sbitmap_free (data->visited_blocks);
9239 /* Find the root node of the loop pre-header extended basic block and
9240 the edges along the trace from the root node to the loop header. */
9243 flow_loop_pre_header_scan (loop)
9249 loop->num_pre_header_edges = 0;
9251 if (loop->num_entries != 1)
9254 ebb = loop->entry_edges[0]->src;
9256 if (ebb != ENTRY_BLOCK_PTR)
9260 /* Count number of edges along trace from loop header to
9261 root of pre-header extended basic block. Usually this is
9262 only one or two edges. */
9264 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
9266 ebb = ebb->pred->src;
9270 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
9271 loop->num_pre_header_edges = num;
9273 /* Store edges in order that they are followed. The source
9274 of the first edge is the root node of the pre-header extended
9275 basic block and the destination of the last last edge is
9277 for (e = loop->entry_edges[0]; num; e = e->src->pred)
9279 loop->pre_header_edges[--num] = e;
9285 /* Return the block for the pre-header of the loop with header
9286 HEADER where DOM specifies the dominator information. Return NULL if
9287 there is no pre-header. */
9290 flow_loop_pre_header_find (header, dom)
9294 basic_block pre_header;
9297 /* If block p is a predecessor of the header and is the only block
9298 that the header does not dominate, then it is the pre-header. */
9300 for (e = header->pred; e; e = e->pred_next)
9302 basic_block node = e->src;
9304 if (node != ENTRY_BLOCK_PTR
9305 && ! TEST_BIT (dom[node->index], header->index))
9307 if (pre_header == NULL)
9311 /* There are multiple edges into the header from outside
9312 the loop so there is no pre-header block. */
9321 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
9322 previously added. The insertion algorithm assumes that the loops
9323 are added in the order found by a depth first search of the CFG. */
9326 flow_loop_tree_node_add (prevloop, loop)
9327 struct loop *prevloop;
9331 if (flow_loop_nested_p (prevloop, loop))
9333 prevloop->inner = loop;
9334 loop->outer = prevloop;
9338 while (prevloop->outer)
9340 if (flow_loop_nested_p (prevloop->outer, loop))
9342 prevloop->next = loop;
9343 loop->outer = prevloop->outer;
9346 prevloop = prevloop->outer;
9349 prevloop->next = loop;
9353 /* Build the loop hierarchy tree for LOOPS. */
9356 flow_loops_tree_build (loops)
9357 struct loops *loops;
9362 num_loops = loops->num;
9366 /* Root the loop hierarchy tree with the first loop found.
9367 Since we used a depth first search this should be the
9369 loops->tree_root = &loops->array[0];
9370 loops->tree_root->outer = loops->tree_root->inner = loops->tree_root->next = NULL;
9372 /* Add the remaining loops to the tree. */
9373 for (i = 1; i < num_loops; i++)
9374 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
9377 /* Helper function to compute loop nesting depth and enclosed loop level
9378 for the natural loop specified by LOOP at the loop depth DEPTH.
9379 Returns the loop level. */
9382 flow_loop_level_compute (loop, depth)
9392 /* Traverse loop tree assigning depth and computing level as the
9393 maximum level of all the inner loops of this loop. The loop
9394 level is equivalent to the height of the loop in the loop tree
9395 and corresponds to the number of enclosed loop levels (including
9397 for (inner = loop->inner; inner; inner = inner->next)
9401 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
9406 loop->level = level;
9407 loop->depth = depth;
9411 /* Compute the loop nesting depth and enclosed loop level for the loop
9412 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
9416 flow_loops_level_compute (loops)
9417 struct loops *loops;
9423 /* Traverse all the outer level loops. */
9424 for (loop = loops->tree_root; loop; loop = loop->next)
9426 level = flow_loop_level_compute (loop, 1);
9434 /* Scan a single natural loop specified by LOOP collecting information
9435 about it specified by FLAGS. */
9438 flow_loop_scan (loops, loop, flags)
9439 struct loops *loops;
9443 /* Determine prerequisites. */
9444 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
9445 flags |= LOOP_EXIT_EDGES;
9447 if (flags & LOOP_ENTRY_EDGES)
9449 /* Find edges which enter the loop header.
9450 Note that the entry edges should only
9451 enter the header of a natural loop. */
9453 = flow_loop_entry_edges_find (loop->header,
9455 &loop->entry_edges);
9458 if (flags & LOOP_EXIT_EDGES)
9460 /* Find edges which exit the loop. */
9462 = flow_loop_exit_edges_find (loop->nodes,
9466 if (flags & LOOP_EXITS_DOMS)
9470 /* Determine which loop nodes dominate all the exits
9472 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
9473 sbitmap_copy (loop->exits_doms, loop->nodes);
9474 for (j = 0; j < loop->num_exits; j++)
9475 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
9476 loops->cfg.dom[loop->exit_edges[j]->src->index]);
9478 /* The header of a natural loop must dominate
9480 if (! TEST_BIT (loop->exits_doms, loop->header->index))
9484 if (flags & LOOP_PRE_HEADER)
9486 /* Look to see if the loop has a pre-header node. */
9488 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
9490 /* Find the blocks within the extended basic block of
9491 the loop pre-header. */
9492 flow_loop_pre_header_scan (loop);
9498 /* Find all the natural loops in the function and save in LOOPS structure
9499 and recalculate loop_depth information in basic block structures.
9500 FLAGS controls which loop information is collected.
9501 Return the number of natural loops found. */
9504 flow_loops_find (loops, flags)
9505 struct loops *loops;
9517 /* This function cannot be repeatedly called with different
9518 flags to build up the loop information. The loop tree
9519 must always be built if this function is called. */
9520 if (! (flags & LOOP_TREE))
9523 memset (loops, 0, sizeof (*loops));
9525 /* Taking care of this degenerate case makes the rest of
9526 this code simpler. */
9527 if (n_basic_blocks == 0)
9533 /* Compute the dominators. */
9534 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
9535 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
9537 /* Count the number of loop edges (back edges). This should be the
9538 same as the number of natural loops. */
9541 for (b = 0; b < n_basic_blocks; b++)
9545 header = BASIC_BLOCK (b);
9546 header->loop_depth = 0;
9548 for (e = header->pred; e; e = e->pred_next)
9550 basic_block latch = e->src;
9552 /* Look for back edges where a predecessor is dominated
9553 by this block. A natural loop has a single entry
9554 node (header) that dominates all the nodes in the
9555 loop. It also has single back edge to the header
9556 from a latch node. Note that multiple natural loops
9557 may share the same header. */
9558 if (b != header->index)
9561 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
9568 /* Compute depth first search order of the CFG so that outer
9569 natural loops will be found before inner natural loops. */
9570 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9571 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
9572 flow_depth_first_order_compute (dfs_order, rc_order);
9574 /* Save CFG derived information to avoid recomputing it. */
9575 loops->cfg.dom = dom;
9576 loops->cfg.dfs_order = dfs_order;
9577 loops->cfg.rc_order = rc_order;
9579 /* Allocate loop structures. */
9581 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
9583 headers = sbitmap_alloc (n_basic_blocks);
9584 sbitmap_zero (headers);
9586 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
9587 sbitmap_zero (loops->shared_headers);
9589 /* Find and record information about all the natural loops
9592 for (b = 0; b < n_basic_blocks; b++)
9596 /* Search the nodes of the CFG in reverse completion order
9597 so that we can find outer loops first. */
9598 header = BASIC_BLOCK (rc_order[b]);
9600 /* Look for all the possible latch blocks for this header. */
9601 for (e = header->pred; e; e = e->pred_next)
9603 basic_block latch = e->src;
9605 /* Look for back edges where a predecessor is dominated
9606 by this block. A natural loop has a single entry
9607 node (header) that dominates all the nodes in the
9608 loop. It also has single back edge to the header
9609 from a latch node. Note that multiple natural loops
9610 may share the same header. */
9611 if (latch != ENTRY_BLOCK_PTR
9612 && TEST_BIT (dom[latch->index], header->index))
9616 loop = loops->array + num_loops;
9618 loop->header = header;
9619 loop->latch = latch;
9620 loop->num = num_loops;
9627 for (i = 0; i < num_loops; i++)
9629 struct loop *loop = &loops->array[i];
9631 /* Keep track of blocks that are loop headers so
9632 that we can tell which loops should be merged. */
9633 if (TEST_BIT (headers, loop->header->index))
9634 SET_BIT (loops->shared_headers, loop->header->index);
9635 SET_BIT (headers, loop->header->index);
9637 /* Find nodes contained within the loop. */
9638 loop->nodes = sbitmap_alloc (n_basic_blocks);
9640 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
9642 /* Compute first and last blocks within the loop.
9643 These are often the same as the loop header and
9644 loop latch respectively, but this is not always
9647 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
9649 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
9651 flow_loop_scan (loops, loop, flags);
9654 /* Natural loops with shared headers may either be disjoint or
9655 nested. Disjoint loops with shared headers cannot be inner
9656 loops and should be merged. For now just mark loops that share
9658 for (i = 0; i < num_loops; i++)
9659 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
9660 loops->array[i].shared = 1;
9662 sbitmap_free (headers);
9666 sbitmap_vector_free (dom);
9669 loops->num = num_loops;
9671 /* Build the loop hierarchy tree. */
9672 flow_loops_tree_build (loops);
9674 /* Assign the loop nesting depth and enclosed loop level for each
9676 loops->levels = flow_loops_level_compute (loops);
9682 /* Update the information regarding the loops in the CFG
9683 specified by LOOPS. */
9685 flow_loops_update (loops, flags)
9686 struct loops *loops;
9689 /* One day we may want to update the current loop data. For now
9690 throw away the old stuff and rebuild what we need. */
9692 flow_loops_free (loops);
9694 return flow_loops_find (loops, flags);
9698 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
9701 flow_loop_outside_edge_p (loop, e)
9702 const struct loop *loop;
9705 if (e->dest != loop->header)
9707 return (e->src == ENTRY_BLOCK_PTR)
9708 || ! TEST_BIT (loop->nodes, e->src->index);
9711 /* Clear LOG_LINKS fields of insns in a chain.
9712 Also clear the global_live_at_{start,end} fields of the basic block
9716 clear_log_links (insns)
9722 for (i = insns; i; i = NEXT_INSN (i))
9726 for (b = 0; b < n_basic_blocks; b++)
9728 basic_block bb = BASIC_BLOCK (b);
9730 bb->global_live_at_start = NULL;
9731 bb->global_live_at_end = NULL;
9734 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
9735 EXIT_BLOCK_PTR->global_live_at_start = NULL;
9738 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
9739 correspond to the hard registers, if any, set in that map. This
9740 could be done far more efficiently by having all sorts of special-cases
9741 with moving single words, but probably isn't worth the trouble. */
9744 reg_set_to_hard_reg_set (to, from)
9750 EXECUTE_IF_SET_IN_BITMAP
9753 if (i >= FIRST_PSEUDO_REGISTER)
9755 SET_HARD_REG_BIT (*to, i);
9759 /* Called once at intialization time. */
9764 static int initialized;
9768 gcc_obstack_init (&flow_obstack);
9769 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
9774 obstack_free (&flow_obstack, flow_firstobj);
9775 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
9779 /* Assume that the preceeding pass has possibly eliminated jump instructions
9780 or converted the unconditional jumps. Eliminate the edges from CFG. */
9783 purge_dead_edges (bb)
9788 if (GET_CODE (insn) == JUMP_INSN && !simplejump_p (insn))
9790 if (GET_CODE (insn) == JUMP_INSN)
9792 for (e = bb->succ; e; e = next)
9794 next = e->succ_next;
9795 if (e->dest == EXIT_BLOCK_PTR || e->dest->head != JUMP_LABEL (insn))
9798 if (bb->succ && bb->succ->succ_next)
9802 bb->succ->probability = REG_BR_PROB_BASE;
9803 bb->succ->count = bb->count;
9806 fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
9809 /* If we don't see a jump insn, we don't know exactly why the block would
9810 have been broken at this point. Look for a simple, non-fallthru edge,
9811 as these are only created by conditional branches. If we find such an
9812 edge we know that there used to be a jump here and can then safely
9813 remove all non-fallthru edges. */
9814 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
9818 for (e = bb->succ; e; e = next)
9820 next = e->succ_next;
9821 if (!(e->flags & EDGE_FALLTHRU))
9824 if (!bb->succ || bb->succ->succ_next)
9826 bb->succ->probability = REG_BR_PROB_BASE;
9827 bb->succ->count = bb->count;
9830 fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n",
9835 /* Search all basic blocks for potentionally dead edges and purge them. */
9838 purge_all_dead_edges ()
9841 for (i = 0; i < n_basic_blocks; i++)
9842 purge_dead_edges (BASIC_BLOCK (i));