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"
140 #include "splay-tree.h"
142 #define obstack_chunk_alloc xmalloc
143 #define obstack_chunk_free free
145 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
146 the stack pointer does not matter. The value is tested only in
147 functions that have frame pointers.
148 No definition is equivalent to always zero. */
149 #ifndef EXIT_IGNORE_STACK
150 #define EXIT_IGNORE_STACK 0
153 #ifndef HAVE_epilogue
154 #define HAVE_epilogue 0
156 #ifndef HAVE_prologue
157 #define HAVE_prologue 0
159 #ifndef HAVE_sibcall_epilogue
160 #define HAVE_sibcall_epilogue 0
164 #define LOCAL_REGNO(REGNO) 0
166 #ifndef EPILOGUE_USES
167 #define EPILOGUE_USES(REGNO) 0
170 #ifdef HAVE_conditional_execution
171 #ifndef REVERSE_CONDEXEC_PREDICATES_P
172 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
176 /* The obstack on which the flow graph components are allocated. */
178 struct obstack flow_obstack;
179 static char *flow_firstobj;
181 /* Number of basic blocks in the current function. */
185 /* Number of edges in the current function. */
189 /* The basic block array. */
191 varray_type basic_block_info;
193 /* The special entry and exit blocks. */
195 struct basic_block_def entry_exit_blocks[2]
200 NULL, /* local_set */
201 NULL, /* cond_local_set */
202 NULL, /* global_live_at_start */
203 NULL, /* global_live_at_end */
205 ENTRY_BLOCK, /* index */
214 NULL, /* local_set */
215 NULL, /* cond_local_set */
216 NULL, /* global_live_at_start */
217 NULL, /* global_live_at_end */
219 EXIT_BLOCK, /* index */
225 /* Nonzero if the second flow pass has completed. */
228 /* Maximum register number used in this function, plus one. */
232 /* Indexed by n, giving various register information */
234 varray_type reg_n_info;
236 /* Size of a regset for the current function,
237 in (1) bytes and (2) elements. */
242 /* Regset of regs live when calls to `setjmp'-like functions happen. */
243 /* ??? Does this exist only for the setjmp-clobbered warning message? */
245 regset regs_live_at_setjmp;
247 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
248 that have to go in the same hard reg.
249 The first two regs in the list are a pair, and the next two
250 are another pair, etc. */
253 /* Callback that determines if it's ok for a function to have no
254 noreturn attribute. */
255 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
257 /* Set of registers that may be eliminable. These are handled specially
258 in updating regs_ever_live. */
260 static HARD_REG_SET elim_reg_set;
262 /* The basic block structure for every insn, indexed by uid. */
264 varray_type basic_block_for_insn;
266 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
267 /* ??? Should probably be using LABEL_NUSES instead. It would take a
268 bit of surgery to be able to use or co-opt the routines in jump. */
270 static rtx label_value_list;
271 static rtx tail_recursion_label_list;
273 /* Holds information for tracking conditional register life information. */
274 struct reg_cond_life_info
276 /* A boolean expression of conditions under which a register is dead. */
278 /* Conditions under which a register is dead at the basic block end. */
281 /* A boolean expression of conditions under which a register has been
285 /* ??? Could store mask of bytes that are dead, so that we could finally
286 track lifetimes of multi-word registers accessed via subregs. */
289 /* For use in communicating between propagate_block and its subroutines.
290 Holds all information needed to compute life and def-use information. */
292 struct propagate_block_info
294 /* The basic block we're considering. */
297 /* Bit N is set if register N is conditionally or unconditionally live. */
300 /* Bit N is set if register N is set this insn. */
303 /* Element N is the next insn that uses (hard or pseudo) register N
304 within the current basic block; or zero, if there is no such insn. */
307 /* Contains a list of all the MEMs we are tracking for dead store
311 /* If non-null, record the set of registers set unconditionally in the
315 /* If non-null, record the set of registers set conditionally in the
317 regset cond_local_set;
319 #ifdef HAVE_conditional_execution
320 /* Indexed by register number, holds a reg_cond_life_info for each
321 register that is not unconditionally live or dead. */
322 splay_tree reg_cond_dead;
324 /* Bit N is set if register N is in an expression in reg_cond_dead. */
328 /* The length of mem_set_list. */
329 int mem_set_list_len;
331 /* Non-zero if the value of CC0 is live. */
334 /* Flags controling the set of information propagate_block collects. */
338 /* Maximum length of pbi->mem_set_list before we start dropping
339 new elements on the floor. */
340 #define MAX_MEM_SET_LIST_LEN 100
342 /* Store the data structures necessary for depth-first search. */
343 struct depth_first_search_dsS {
344 /* stack for backtracking during the algorithm */
347 /* number of edges in the stack. That is, positions 0, ..., sp-1
351 /* record of basic blocks already seen by depth-first search */
352 sbitmap visited_blocks;
354 typedef struct depth_first_search_dsS *depth_first_search_ds;
356 /* Have print_rtl_and_abort give the same information that fancy_abort
358 #define print_rtl_and_abort() \
359 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
361 /* Forward declarations */
362 static int count_basic_blocks PARAMS ((rtx));
363 static void find_basic_blocks_1 PARAMS ((rtx));
364 static rtx find_label_refs PARAMS ((rtx, rtx));
365 static void clear_edges PARAMS ((void));
366 static void make_edges PARAMS ((rtx));
367 static void make_label_edge PARAMS ((sbitmap *, basic_block,
369 static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
370 static void mark_critical_edges PARAMS ((void));
372 static void commit_one_edge_insertion PARAMS ((edge));
374 static void delete_unreachable_blocks PARAMS ((void));
375 static int can_delete_note_p PARAMS ((rtx));
376 static void expunge_block PARAMS ((basic_block));
377 static int can_delete_label_p PARAMS ((rtx));
378 static int tail_recursion_label_p PARAMS ((rtx));
379 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
381 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
383 static int merge_blocks PARAMS ((edge,basic_block,basic_block));
384 static void try_merge_blocks PARAMS ((void));
385 static void tidy_fallthru_edges PARAMS ((void));
386 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
387 static void verify_wide_reg PARAMS ((int, rtx, rtx));
388 static void verify_local_live_at_start PARAMS ((regset, basic_block));
389 static int noop_move_p PARAMS ((rtx));
390 static void delete_noop_moves PARAMS ((rtx));
391 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
392 static void notice_stack_pointer_modification PARAMS ((rtx));
393 static void mark_reg PARAMS ((rtx, void *));
394 static void mark_regs_live_at_end PARAMS ((regset));
395 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
396 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
397 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
398 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
399 static int insn_dead_p PARAMS ((struct propagate_block_info *,
401 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
403 static void mark_set_regs PARAMS ((struct propagate_block_info *,
405 static void mark_set_1 PARAMS ((struct propagate_block_info *,
406 enum rtx_code, rtx, rtx,
408 #ifdef HAVE_conditional_execution
409 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
411 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
412 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
413 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
415 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
416 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
417 static rtx not_reg_cond PARAMS ((rtx));
418 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
421 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
422 rtx, rtx, rtx, rtx, rtx));
423 static void find_auto_inc PARAMS ((struct propagate_block_info *,
425 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
427 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
429 static void mark_used_reg PARAMS ((struct propagate_block_info *,
431 static void mark_used_regs PARAMS ((struct propagate_block_info *,
433 void dump_flow_info PARAMS ((FILE *));
434 void debug_flow_info PARAMS ((void));
435 static void dump_edge_info PARAMS ((FILE *, edge, int));
436 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
440 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
442 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
444 static void remove_fake_successors PARAMS ((basic_block));
445 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
447 static void flow_edge_list_print PARAMS ((const char *, const edge *,
449 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
451 static int flow_loop_nested_p PARAMS ((struct loop *,
453 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
455 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
456 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
457 static int flow_depth_first_order_compute PARAMS ((int *, int *));
458 static void flow_dfs_compute_reverse_init
459 PARAMS ((depth_first_search_ds));
460 static void flow_dfs_compute_reverse_add_bb
461 PARAMS ((depth_first_search_ds, basic_block));
462 static basic_block flow_dfs_compute_reverse_execute
463 PARAMS ((depth_first_search_ds));
464 static void flow_dfs_compute_reverse_finish
465 PARAMS ((depth_first_search_ds));
466 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
467 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
469 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
470 static void flow_loops_tree_build PARAMS ((struct loops *));
471 static int flow_loop_level_compute PARAMS ((struct loop *, int));
472 static int flow_loops_level_compute PARAMS ((struct loops *));
473 static void allocate_bb_life_data PARAMS ((void));
474 static void find_sub_basic_blocks PARAMS ((basic_block));
476 /* Find basic blocks of the current function.
477 F is the first insn of the function and NREGS the number of register
481 find_basic_blocks (f, nregs, file)
483 int nregs ATTRIBUTE_UNUSED;
484 FILE *file ATTRIBUTE_UNUSED;
488 /* Flush out existing data. */
489 if (basic_block_info != NULL)
495 /* Clear bb->aux on all extant basic blocks. We'll use this as a
496 tag for reuse during create_basic_block, just in case some pass
497 copies around basic block notes improperly. */
498 for (i = 0; i < n_basic_blocks; ++i)
499 BASIC_BLOCK (i)->aux = NULL;
501 VARRAY_FREE (basic_block_info);
504 n_basic_blocks = count_basic_blocks (f);
506 /* Size the basic block table. The actual structures will be allocated
507 by find_basic_blocks_1, since we want to keep the structure pointers
508 stable across calls to find_basic_blocks. */
509 /* ??? This whole issue would be much simpler if we called find_basic_blocks
510 exactly once, and thereafter we don't have a single long chain of
511 instructions at all until close to the end of compilation when we
512 actually lay them out. */
514 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
516 find_basic_blocks_1 (f);
518 /* Record the block to which an insn belongs. */
519 /* ??? This should be done another way, by which (perhaps) a label is
520 tagged directly with the basic block that it starts. It is used for
521 more than that currently, but IMO that is the only valid use. */
523 max_uid = get_max_uid ();
525 /* Leave space for insns life_analysis makes in some cases for auto-inc.
526 These cases are rare, so we don't need too much space. */
527 max_uid += max_uid / 10;
530 compute_bb_for_insn (max_uid);
532 /* Discover the edges of our cfg. */
533 make_edges (label_value_list);
535 /* Do very simple cleanup now, for the benefit of code that runs between
536 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
537 tidy_fallthru_edges ();
539 mark_critical_edges ();
541 #ifdef ENABLE_CHECKING
547 check_function_return_warnings ()
549 if (warn_missing_noreturn
550 && !TREE_THIS_VOLATILE (cfun->decl)
551 && EXIT_BLOCK_PTR->pred == NULL
552 && (lang_missing_noreturn_ok_p
553 && !lang_missing_noreturn_ok_p (cfun->decl)))
554 warning ("function might be possible candidate for attribute `noreturn'");
556 /* If we have a path to EXIT, then we do return. */
557 if (TREE_THIS_VOLATILE (cfun->decl)
558 && EXIT_BLOCK_PTR->pred != NULL)
559 warning ("`noreturn' function does return");
561 /* If the clobber_return_insn appears in some basic block, then we
562 do reach the end without returning a value. */
563 else if (warn_return_type
564 && cfun->x_clobber_return_insn != NULL
565 && EXIT_BLOCK_PTR->pred != NULL)
567 int max_uid = get_max_uid ();
569 /* If clobber_return_insn was excised by jump1, then renumber_insns
570 can make max_uid smaller than the number still recorded in our rtx.
571 That's fine, since this is a quick way of verifying that the insn
572 is no longer in the chain. */
573 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
575 /* Recompute insn->block mapping, since the initial mapping is
576 set before we delete unreachable blocks. */
577 compute_bb_for_insn (max_uid);
579 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
580 warning ("control reaches end of non-void function");
585 /* Count the basic blocks of the function. */
588 count_basic_blocks (f)
592 register RTX_CODE prev_code;
593 register int count = 0;
594 int saw_abnormal_edge = 0;
596 prev_code = JUMP_INSN;
597 for (insn = f; insn; insn = NEXT_INSN (insn))
599 enum rtx_code code = GET_CODE (insn);
601 if (code == CODE_LABEL
602 || (GET_RTX_CLASS (code) == 'i'
603 && (prev_code == JUMP_INSN
604 || prev_code == BARRIER
605 || saw_abnormal_edge)))
607 saw_abnormal_edge = 0;
611 /* Record whether this insn created an edge. */
612 if (code == CALL_INSN)
616 /* If there is a nonlocal goto label and the specified
617 region number isn't -1, we have an edge. */
618 if (nonlocal_goto_handler_labels
619 && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
620 || INTVAL (XEXP (note, 0)) >= 0))
621 saw_abnormal_edge = 1;
623 else if (can_throw_internal (insn))
624 saw_abnormal_edge = 1;
626 else if (flag_non_call_exceptions
628 && can_throw_internal (insn))
629 saw_abnormal_edge = 1;
635 /* The rest of the compiler works a bit smoother when we don't have to
636 check for the edge case of do-nothing functions with no basic blocks. */
639 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
646 /* Scan a list of insns for labels referred to other than by jumps.
647 This is used to scan the alternatives of a call placeholder. */
649 find_label_refs (f, lvl)
655 for (insn = f; insn; insn = NEXT_INSN (insn))
656 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
660 /* Make a list of all labels referred to other than by jumps
661 (which just don't have the REG_LABEL notes).
663 Make a special exception for labels followed by an ADDR*VEC,
664 as this would be a part of the tablejump setup code.
666 Make a special exception to registers loaded with label
667 values just before jump insns that use them. */
669 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
670 if (REG_NOTE_KIND (note) == REG_LABEL)
672 rtx lab = XEXP (note, 0), next;
674 if ((next = next_nonnote_insn (lab)) != NULL
675 && GET_CODE (next) == JUMP_INSN
676 && (GET_CODE (PATTERN (next)) == ADDR_VEC
677 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
679 else if (GET_CODE (lab) == NOTE)
681 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
682 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
685 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
692 /* Assume that someone emitted code with control flow instructions to the
693 basic block. Update the data structure. */
695 find_sub_basic_blocks (bb)
698 rtx first_insn = bb->head, insn;
700 edge succ_list = bb->succ;
701 rtx jump_insn = NULL_RTX;
705 basic_block first_bb = bb, last_bb;
708 if (GET_CODE (first_insn) == LABEL_REF)
709 first_insn = NEXT_INSN (first_insn);
710 first_insn = NEXT_INSN (first_insn);
714 /* Scan insn chain and try to find new basic block boundaries. */
717 enum rtx_code code = GET_CODE (insn);
721 /* We need some special care for those expressions. */
722 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
723 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
732 /* On code label, split current basic block. */
734 falltru = split_block (bb, PREV_INSN (insn));
739 remove_edge (falltru);
743 if (LABEL_ALTERNATE_NAME (insn))
744 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
747 /* In case we've previously split insn on the JUMP_INSN, move the
748 block header to proper place. */
751 falltru = split_block (bb, PREV_INSN (insn));
761 insn = NEXT_INSN (insn);
763 /* Last basic block must end in the original BB end. */
767 /* Wire in the original edges for last basic block. */
770 bb->succ = succ_list;
772 succ_list->src = bb, succ_list = succ_list->succ_next;
775 bb->succ = succ_list;
777 /* Now re-scan and wire in all edges. This expect simple (conditional)
778 jumps at the end of each new basic blocks. */
780 for (i = first_bb->index; i < last_bb->index; i++)
782 bb = BASIC_BLOCK (i);
783 if (GET_CODE (bb->end) == JUMP_INSN)
785 mark_jump_label (PATTERN (bb->end), bb->end, 0, 0);
786 make_label_edge (NULL, bb, JUMP_LABEL (bb->end), 0);
788 insn = NEXT_INSN (insn);
792 /* Find all basic blocks of the function whose first insn is F.
794 Collect and return a list of labels whose addresses are taken. This
795 will be used in make_edges for use with computed gotos. */
798 find_basic_blocks_1 (f)
801 register rtx insn, next;
803 rtx bb_note = NULL_RTX;
809 /* We process the instructions in a slightly different way than we did
810 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
811 closed out the previous block, so that it gets attached at the proper
812 place. Since this form should be equivalent to the previous,
813 count_basic_blocks continues to use the old form as a check. */
815 for (insn = f; insn; insn = next)
817 enum rtx_code code = GET_CODE (insn);
819 next = NEXT_INSN (insn);
825 int kind = NOTE_LINE_NUMBER (insn);
827 /* Look for basic block notes with which to keep the
828 basic_block_info pointers stable. Unthread the note now;
829 we'll put it back at the right place in create_basic_block.
830 Or not at all if we've already found a note in this block. */
831 if (kind == NOTE_INSN_BASIC_BLOCK)
833 if (bb_note == NULL_RTX)
836 next = flow_delete_insn (insn);
842 /* A basic block starts at a label. If we've closed one off due
843 to a barrier or some such, no need to do it again. */
844 if (head != NULL_RTX)
846 /* While we now have edge lists with which other portions of
847 the compiler might determine a call ending a basic block
848 does not imply an abnormal edge, it will be a bit before
849 everything can be updated. So continue to emit a noop at
850 the end of such a block. */
851 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
853 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
854 end = emit_insn_after (nop, end);
857 create_basic_block (i++, head, end, bb_note);
865 /* A basic block ends at a jump. */
866 if (head == NULL_RTX)
870 /* ??? Make a special check for table jumps. The way this
871 happens is truly and amazingly gross. We are about to
872 create a basic block that contains just a code label and
873 an addr*vec jump insn. Worse, an addr_diff_vec creates
874 its own natural loop.
876 Prevent this bit of brain damage, pasting things together
877 correctly in make_edges.
879 The correct solution involves emitting the table directly
880 on the tablejump instruction as a note, or JUMP_LABEL. */
882 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
883 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
891 goto new_bb_inclusive;
894 /* A basic block ends at a barrier. It may be that an unconditional
895 jump already closed the basic block -- no need to do it again. */
896 if (head == NULL_RTX)
899 /* While we now have edge lists with which other portions of the
900 compiler might determine a call ending a basic block does not
901 imply an abnormal edge, it will be a bit before everything can
902 be updated. So continue to emit a noop at the end of such a
904 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
906 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
907 end = emit_insn_after (nop, end);
909 goto new_bb_exclusive;
913 /* Record whether this call created an edge. */
914 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
915 int region = (note ? INTVAL (XEXP (note, 0)) : 0);
917 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
919 /* Scan each of the alternatives for label refs. */
920 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
921 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
922 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
923 /* Record its tail recursion label, if any. */
924 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
925 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
928 /* A basic block ends at a call that can either throw or
929 do a non-local goto. */
930 if ((nonlocal_goto_handler_labels && region >= 0)
931 || can_throw_internal (insn))
934 if (head == NULL_RTX)
939 create_basic_block (i++, head, end, bb_note);
940 head = end = NULL_RTX;
948 /* Non-call exceptions generate new blocks just like calls. */
949 if (flag_non_call_exceptions && can_throw_internal (insn))
950 goto new_bb_inclusive;
952 if (head == NULL_RTX)
961 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
965 /* Make a list of all labels referred to other than by jumps.
967 Make a special exception for labels followed by an ADDR*VEC,
968 as this would be a part of the tablejump setup code.
970 Make a special exception to registers loaded with label
971 values just before jump insns that use them. */
973 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
974 if (REG_NOTE_KIND (note) == REG_LABEL)
976 rtx lab = XEXP (note, 0), next;
978 if ((next = next_nonnote_insn (lab)) != NULL
979 && GET_CODE (next) == JUMP_INSN
980 && (GET_CODE (PATTERN (next)) == ADDR_VEC
981 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
983 else if (GET_CODE (lab) == NOTE)
985 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
986 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
989 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
994 if (head != NULL_RTX)
995 create_basic_block (i++, head, end, bb_note);
997 flow_delete_insn (bb_note);
999 if (i != n_basic_blocks)
1002 label_value_list = lvl;
1003 tail_recursion_label_list = trll;
1006 /* Tidy the CFG by deleting unreachable code and whatnot. */
1011 delete_unreachable_blocks ();
1012 try_merge_blocks ();
1013 mark_critical_edges ();
1015 /* Kill the data we won't maintain. */
1016 free_EXPR_LIST_list (&label_value_list);
1017 free_EXPR_LIST_list (&tail_recursion_label_list);
1020 /* Create a new basic block consisting of the instructions between
1021 HEAD and END inclusive. Reuses the note and basic block struct
1022 in BB_NOTE, if any. */
1025 create_basic_block (index, head, end, bb_note)
1027 rtx head, end, bb_note;
1032 && ! RTX_INTEGRATED_P (bb_note)
1033 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
1036 /* If we found an existing note, thread it back onto the chain. */
1040 if (GET_CODE (head) == CODE_LABEL)
1044 after = PREV_INSN (head);
1048 if (after != bb_note && NEXT_INSN (after) != bb_note)
1049 reorder_insns (bb_note, bb_note, after);
1053 /* Otherwise we must create a note and a basic block structure.
1054 Since we allow basic block structs in rtl, give the struct
1055 the same lifetime by allocating it off the function obstack
1056 rather than using malloc. */
1058 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1059 memset (bb, 0, sizeof (*bb));
1061 if (GET_CODE (head) == CODE_LABEL)
1062 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
1065 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
1068 NOTE_BASIC_BLOCK (bb_note) = bb;
1071 /* Always include the bb note in the block. */
1072 if (NEXT_INSN (end) == bb_note)
1078 BASIC_BLOCK (index) = bb;
1080 /* Tag the block so that we know it has been used when considering
1081 other basic block notes. */
1085 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1086 indexed by INSN_UID. MAX is the size of the array. */
1089 compute_bb_for_insn (max)
1094 if (basic_block_for_insn)
1095 VARRAY_FREE (basic_block_for_insn);
1096 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1098 for (i = 0; i < n_basic_blocks; ++i)
1100 basic_block bb = BASIC_BLOCK (i);
1107 int uid = INSN_UID (insn);
1109 VARRAY_BB (basic_block_for_insn, uid) = bb;
1112 insn = NEXT_INSN (insn);
1117 /* Free the memory associated with the edge structures. */
1125 for (i = 0; i < n_basic_blocks; ++i)
1127 basic_block bb = BASIC_BLOCK (i);
1129 for (e = bb->succ; e; e = n)
1139 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1145 ENTRY_BLOCK_PTR->succ = 0;
1146 EXIT_BLOCK_PTR->pred = 0;
1151 /* Identify the edges between basic blocks.
1153 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1154 that are otherwise unreachable may be reachable with a non-local goto.
1156 BB_EH_END is an array indexed by basic block number in which we record
1157 the list of exception regions active at the end of the basic block. */
1160 make_edges (label_value_list)
1161 rtx label_value_list;
1164 sbitmap *edge_cache = NULL;
1166 /* Assume no computed jump; revise as we create edges. */
1167 current_function_has_computed_jump = 0;
1169 /* Heavy use of computed goto in machine-generated code can lead to
1170 nearly fully-connected CFGs. In that case we spend a significant
1171 amount of time searching the edge lists for duplicates. */
1172 if (forced_labels || label_value_list)
1174 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1175 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1178 /* By nature of the way these get numbered, block 0 is always the entry. */
1179 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1181 for (i = 0; i < n_basic_blocks; ++i)
1183 basic_block bb = BASIC_BLOCK (i);
1186 int force_fallthru = 0;
1188 if (GET_CODE (bb->head) == CODE_LABEL
1189 && LABEL_ALTERNATE_NAME (bb->head))
1190 make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
1192 /* Examine the last instruction of the block, and discover the
1193 ways we can leave the block. */
1196 code = GET_CODE (insn);
1199 if (code == JUMP_INSN)
1203 /* Recognize exception handling placeholders. */
1204 if (GET_CODE (PATTERN (insn)) == RESX)
1205 make_eh_edge (edge_cache, bb, insn);
1207 /* Recognize a non-local goto as a branch outside the
1208 current function. */
1209 else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1212 /* ??? Recognize a tablejump and do the right thing. */
1213 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1214 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1215 && GET_CODE (tmp) == JUMP_INSN
1216 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1217 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1222 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1223 vec = XVEC (PATTERN (tmp), 0);
1225 vec = XVEC (PATTERN (tmp), 1);
1227 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1228 make_label_edge (edge_cache, bb,
1229 XEXP (RTVEC_ELT (vec, j), 0), 0);
1231 /* Some targets (eg, ARM) emit a conditional jump that also
1232 contains the out-of-range target. Scan for these and
1233 add an edge if necessary. */
1234 if ((tmp = single_set (insn)) != NULL
1235 && SET_DEST (tmp) == pc_rtx
1236 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1237 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1238 make_label_edge (edge_cache, bb,
1239 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1241 #ifdef CASE_DROPS_THROUGH
1242 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1243 us naturally detecting fallthru into the next block. */
1248 /* If this is a computed jump, then mark it as reaching
1249 everything on the label_value_list and forced_labels list. */
1250 else if (computed_jump_p (insn))
1252 current_function_has_computed_jump = 1;
1254 for (x = label_value_list; x; x = XEXP (x, 1))
1255 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1257 for (x = forced_labels; x; x = XEXP (x, 1))
1258 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1261 /* Returns create an exit out. */
1262 else if (returnjump_p (insn))
1263 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1265 /* Otherwise, we have a plain conditional or unconditional jump. */
1268 if (! JUMP_LABEL (insn))
1270 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1274 /* If this is a sibling call insn, then this is in effect a
1275 combined call and return, and so we need an edge to the
1276 exit block. No need to worry about EH edges, since we
1277 wouldn't have created the sibling call in the first place. */
1279 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1280 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1281 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1283 /* If this is a CALL_INSN, then mark it as reaching the active EH
1284 handler for this CALL_INSN. If we're handling non-call
1285 exceptions then any insn can reach any of the active handlers.
1287 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1289 else if (code == CALL_INSN || flag_non_call_exceptions)
1291 /* Add any appropriate EH edges. */
1292 make_eh_edge (edge_cache, bb, insn);
1294 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1296 /* ??? This could be made smarter: in some cases it's possible
1297 to tell that certain calls will not do a nonlocal goto.
1299 For example, if the nested functions that do the nonlocal
1300 gotos do not have their addresses taken, then only calls to
1301 those functions or to other nested functions that use them
1302 could possibly do nonlocal gotos. */
1303 /* We do know that a REG_EH_REGION note with a value less
1304 than 0 is guaranteed not to perform a non-local goto. */
1305 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1306 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1307 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1308 make_label_edge (edge_cache, bb, XEXP (x, 0),
1309 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1313 /* Find out if we can drop through to the next block. */
1314 insn = next_nonnote_insn (insn);
1315 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1316 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1317 else if (i + 1 < n_basic_blocks)
1319 rtx tmp = BLOCK_HEAD (i + 1);
1320 if (GET_CODE (tmp) == NOTE)
1321 tmp = next_nonnote_insn (tmp);
1322 if (force_fallthru || insn == tmp)
1323 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1328 sbitmap_vector_free (edge_cache);
1331 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1332 about the edge that is accumulated between calls. */
1335 make_edge (edge_cache, src, dst, flags)
1336 sbitmap *edge_cache;
1337 basic_block src, dst;
1343 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1344 many edges to them, and we didn't allocate memory for it. */
1345 use_edge_cache = (edge_cache
1346 && src != ENTRY_BLOCK_PTR
1347 && dst != EXIT_BLOCK_PTR);
1349 /* Make sure we don't add duplicate edges. */
1350 switch (use_edge_cache)
1353 /* Quick test for non-existance of the edge. */
1354 if (! TEST_BIT (edge_cache[src->index], dst->index))
1357 /* The edge exists; early exit if no work to do. */
1363 for (e = src->succ; e; e = e->succ_next)
1372 e = (edge) xcalloc (1, sizeof (*e));
1375 e->succ_next = src->succ;
1376 e->pred_next = dst->pred;
1385 SET_BIT (edge_cache[src->index], dst->index);
1388 /* Create an edge from a basic block to a label. */
1391 make_label_edge (edge_cache, src, label, flags)
1392 sbitmap *edge_cache;
1397 if (GET_CODE (label) != CODE_LABEL)
1400 /* If the label was never emitted, this insn is junk, but avoid a
1401 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1402 as a result of a syntax error and a diagnostic has already been
1405 if (INSN_UID (label) == 0)
1408 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1411 /* Create the edges generated by INSN in REGION. */
1414 make_eh_edge (edge_cache, src, insn)
1415 sbitmap *edge_cache;
1419 int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1422 handlers = reachable_handlers (insn);
1424 for (i = handlers; i; i = XEXP (i, 1))
1425 make_label_edge (edge_cache, src, XEXP (i, 0),
1426 EDGE_ABNORMAL | EDGE_EH | is_call);
1428 free_INSN_LIST_list (&handlers);
1431 /* Identify critical edges and set the bits appropriately. */
1434 mark_critical_edges ()
1436 int i, n = n_basic_blocks;
1439 /* We begin with the entry block. This is not terribly important now,
1440 but could be if a front end (Fortran) implemented alternate entry
1442 bb = ENTRY_BLOCK_PTR;
1449 /* (1) Critical edges must have a source with multiple successors. */
1450 if (bb->succ && bb->succ->succ_next)
1452 for (e = bb->succ; e; e = e->succ_next)
1454 /* (2) Critical edges must have a destination with multiple
1455 predecessors. Note that we know there is at least one
1456 predecessor -- the edge we followed to get here. */
1457 if (e->dest->pred->pred_next)
1458 e->flags |= EDGE_CRITICAL;
1460 e->flags &= ~EDGE_CRITICAL;
1465 for (e = bb->succ; e; e = e->succ_next)
1466 e->flags &= ~EDGE_CRITICAL;
1471 bb = BASIC_BLOCK (i);
1475 /* Split a block BB after insn INSN creating a new fallthru edge.
1476 Return the new edge. Note that to keep other parts of the compiler happy,
1477 this function renumbers all the basic blocks so that the new
1478 one has a number one greater than the block split. */
1481 split_block (bb, insn)
1491 /* There is no point splitting the block after its end. */
1492 if (bb->end == insn)
1495 /* Create the new structures. */
1496 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1497 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1500 memset (new_bb, 0, sizeof (*new_bb));
1502 new_bb->head = NEXT_INSN (insn);
1503 new_bb->end = bb->end;
1506 new_bb->succ = bb->succ;
1507 bb->succ = new_edge;
1508 new_bb->pred = new_edge;
1509 new_bb->count = bb->count;
1510 new_bb->loop_depth = bb->loop_depth;
1513 new_edge->dest = new_bb;
1514 new_edge->flags = EDGE_FALLTHRU;
1515 new_edge->probability = REG_BR_PROB_BASE;
1516 new_edge->count = bb->count;
1518 /* Redirect the src of the successor edges of bb to point to new_bb. */
1519 for (e = new_bb->succ; e; e = e->succ_next)
1522 /* Place the new block just after the block being split. */
1523 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1525 /* Some parts of the compiler expect blocks to be number in
1526 sequential order so insert the new block immediately after the
1527 block being split.. */
1529 for (i = n_basic_blocks - 1; i > j + 1; --i)
1531 basic_block tmp = BASIC_BLOCK (i - 1);
1532 BASIC_BLOCK (i) = tmp;
1536 BASIC_BLOCK (i) = new_bb;
1539 if (GET_CODE (new_bb->head) == CODE_LABEL)
1541 /* Create the basic block note. */
1542 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK,
1544 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1548 /* Create the basic block note. */
1549 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1551 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1552 new_bb->head = bb_note;
1555 update_bb_for_insn (new_bb);
1557 if (bb->global_live_at_start)
1559 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1560 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1561 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1563 /* We now have to calculate which registers are live at the end
1564 of the split basic block and at the start of the new basic
1565 block. Start with those registers that are known to be live
1566 at the end of the original basic block and get
1567 propagate_block to determine which registers are live. */
1568 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1569 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1570 COPY_REG_SET (bb->global_live_at_end,
1571 new_bb->global_live_at_start);
1578 /* Split a (typically critical) edge. Return the new block.
1579 Abort on abnormal edges.
1581 ??? The code generally expects to be called on critical edges.
1582 The case of a block ending in an unconditional jump to a
1583 block with multiple predecessors is not handled optimally. */
1586 split_edge (edge_in)
1589 basic_block old_pred, bb, old_succ;
1594 /* Abnormal edges cannot be split. */
1595 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1598 old_pred = edge_in->src;
1599 old_succ = edge_in->dest;
1601 /* Remove the existing edge from the destination's pred list. */
1604 for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next)
1606 *pp = edge_in->pred_next;
1607 edge_in->pred_next = NULL;
1610 /* Create the new structures. */
1611 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1612 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
1615 memset (bb, 0, sizeof (*bb));
1617 /* ??? This info is likely going to be out of date very soon. */
1618 if (old_succ->global_live_at_start)
1620 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1621 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1622 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
1623 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
1628 bb->succ = edge_out;
1629 bb->count = edge_in->count;
1632 edge_in->flags &= ~EDGE_CRITICAL;
1634 edge_out->pred_next = old_succ->pred;
1635 edge_out->succ_next = NULL;
1637 edge_out->dest = old_succ;
1638 edge_out->flags = EDGE_FALLTHRU;
1639 edge_out->probability = REG_BR_PROB_BASE;
1640 edge_out->count = edge_in->count;
1642 old_succ->pred = edge_out;
1644 /* Tricky case -- if there existed a fallthru into the successor
1645 (and we're not it) we must add a new unconditional jump around
1646 the new block we're actually interested in.
1648 Further, if that edge is critical, this means a second new basic
1649 block must be created to hold it. In order to simplify correct
1650 insn placement, do this before we touch the existing basic block
1651 ordering for the block we were really wanting. */
1652 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1655 for (e = edge_out->pred_next; e; e = e->pred_next)
1656 if (e->flags & EDGE_FALLTHRU)
1661 basic_block jump_block;
1664 if ((e->flags & EDGE_CRITICAL) == 0
1665 && e->src != ENTRY_BLOCK_PTR)
1667 /* Non critical -- we can simply add a jump to the end
1668 of the existing predecessor. */
1669 jump_block = e->src;
1673 /* We need a new block to hold the jump. The simplest
1674 way to do the bulk of the work here is to recursively
1676 jump_block = split_edge (e);
1677 e = jump_block->succ;
1680 /* Now add the jump insn ... */
1681 pos = emit_jump_insn_after (gen_jump (old_succ->head),
1683 jump_block->end = pos;
1684 if (basic_block_for_insn)
1685 set_block_for_insn (pos, jump_block);
1686 emit_barrier_after (pos);
1688 /* ... let jump know that label is in use, ... */
1689 JUMP_LABEL (pos) = old_succ->head;
1690 ++LABEL_NUSES (old_succ->head);
1692 /* ... and clear fallthru on the outgoing edge. */
1693 e->flags &= ~EDGE_FALLTHRU;
1695 /* Continue splitting the interesting edge. */
1699 /* Place the new block just in front of the successor. */
1700 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1701 if (old_succ == EXIT_BLOCK_PTR)
1702 j = n_basic_blocks - 1;
1704 j = old_succ->index;
1705 for (i = n_basic_blocks - 1; i > j; --i)
1707 basic_block tmp = BASIC_BLOCK (i - 1);
1708 BASIC_BLOCK (i) = tmp;
1711 BASIC_BLOCK (i) = bb;
1714 /* Create the basic block note.
1716 Where we place the note can have a noticable impact on the generated
1717 code. Consider this cfg:
1727 If we need to insert an insn on the edge from block 0 to block 1,
1728 we want to ensure the instructions we insert are outside of any
1729 loop notes that physically sit between block 0 and block 1. Otherwise
1730 we confuse the loop optimizer into thinking the loop is a phony. */
1731 if (old_succ != EXIT_BLOCK_PTR
1732 && PREV_INSN (old_succ->head)
1733 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
1734 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
1735 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1736 PREV_INSN (old_succ->head));
1737 else if (old_succ != EXIT_BLOCK_PTR)
1738 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
1740 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
1741 NOTE_BASIC_BLOCK (bb_note) = bb;
1742 bb->head = bb->end = bb_note;
1744 /* Not quite simple -- for non-fallthru edges, we must adjust the
1745 predecessor's jump instruction to target our new block. */
1746 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1748 rtx tmp, insn = old_pred->end;
1749 rtx old_label = old_succ->head;
1750 rtx new_label = gen_label_rtx ();
1752 if (GET_CODE (insn) != JUMP_INSN)
1755 /* ??? Recognize a tablejump and adjust all matching cases. */
1756 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1757 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1758 && GET_CODE (tmp) == JUMP_INSN
1759 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1760 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1765 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1766 vec = XVEC (PATTERN (tmp), 0);
1768 vec = XVEC (PATTERN (tmp), 1);
1770 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1771 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1773 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
1774 --LABEL_NUSES (old_label);
1775 ++LABEL_NUSES (new_label);
1778 /* Handle casesi dispatch insns */
1779 if ((tmp = single_set (insn)) != NULL
1780 && SET_DEST (tmp) == pc_rtx
1781 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1782 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1783 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1785 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1787 --LABEL_NUSES (old_label);
1788 ++LABEL_NUSES (new_label);
1793 /* This would have indicated an abnormal edge. */
1794 if (computed_jump_p (insn))
1797 /* A return instruction can't be redirected. */
1798 if (returnjump_p (insn))
1801 /* If the insn doesn't go where we think, we're confused. */
1802 if (JUMP_LABEL (insn) != old_label)
1805 redirect_jump (insn, new_label, 0);
1808 emit_label_before (new_label, bb_note);
1809 bb->head = new_label;
1815 /* Queue instructions for insertion on an edge between two basic blocks.
1816 The new instructions and basic blocks (if any) will not appear in the
1817 CFG until commit_edge_insertions is called. */
1820 insert_insn_on_edge (pattern, e)
1824 /* We cannot insert instructions on an abnormal critical edge.
1825 It will be easier to find the culprit if we die now. */
1826 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
1827 == (EDGE_ABNORMAL|EDGE_CRITICAL))
1830 if (e->insns == NULL_RTX)
1833 push_to_sequence (e->insns);
1835 emit_insn (pattern);
1837 e->insns = get_insns ();
1841 /* Update the CFG for the instructions queued on edge E. */
1844 commit_one_edge_insertion (e)
1847 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1850 /* Pull the insns off the edge now since the edge might go away. */
1852 e->insns = NULL_RTX;
1854 /* Figure out where to put these things. If the destination has
1855 one predecessor, insert there. Except for the exit block. */
1856 if (e->dest->pred->pred_next == NULL
1857 && e->dest != EXIT_BLOCK_PTR)
1861 /* Get the location correct wrt a code label, and "nice" wrt
1862 a basic block note, and before everything else. */
1864 if (GET_CODE (tmp) == CODE_LABEL)
1865 tmp = NEXT_INSN (tmp);
1866 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1867 tmp = NEXT_INSN (tmp);
1868 if (tmp == bb->head)
1871 after = PREV_INSN (tmp);
1874 /* If the source has one successor and the edge is not abnormal,
1875 insert there. Except for the entry block. */
1876 else if ((e->flags & EDGE_ABNORMAL) == 0
1877 && e->src->succ->succ_next == NULL
1878 && e->src != ENTRY_BLOCK_PTR)
1881 /* It is possible to have a non-simple jump here. Consider a target
1882 where some forms of unconditional jumps clobber a register. This
1883 happens on the fr30 for example.
1885 We know this block has a single successor, so we can just emit
1886 the queued insns before the jump. */
1887 if (GET_CODE (bb->end) == JUMP_INSN)
1893 /* We'd better be fallthru, or we've lost track of what's what. */
1894 if ((e->flags & EDGE_FALLTHRU) == 0)
1901 /* Otherwise we must split the edge. */
1904 bb = split_edge (e);
1908 /* Now that we've found the spot, do the insertion. */
1910 /* Set the new block number for these insns, if structure is allocated. */
1911 if (basic_block_for_insn)
1914 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
1915 set_block_for_insn (i, bb);
1920 emit_insns_before (insns, before);
1921 if (before == bb->head)
1924 last = prev_nonnote_insn (before);
1928 last = emit_insns_after (insns, after);
1929 if (after == bb->end)
1933 if (returnjump_p (last))
1935 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1936 This is not currently a problem because this only happens
1937 for the (single) epilogue, which already has a fallthru edge
1941 if (e->dest != EXIT_BLOCK_PTR
1942 || e->succ_next != NULL
1943 || (e->flags & EDGE_FALLTHRU) == 0)
1945 e->flags &= ~EDGE_FALLTHRU;
1947 emit_barrier_after (last);
1951 flow_delete_insn (before);
1953 else if (GET_CODE (last) == JUMP_INSN)
1955 find_sub_basic_blocks (bb);
1958 /* Update the CFG for all queued instructions. */
1961 commit_edge_insertions ()
1966 #ifdef ENABLE_CHECKING
1967 verify_flow_info ();
1971 bb = ENTRY_BLOCK_PTR;
1976 for (e = bb->succ; e; e = next)
1978 next = e->succ_next;
1980 commit_one_edge_insertion (e);
1983 if (++i >= n_basic_blocks)
1985 bb = BASIC_BLOCK (i);
1989 /* Add fake edges to the function exit for any non constant calls in
1990 the bitmap of blocks specified by BLOCKS or to the whole CFG if
1991 BLOCKS is zero. Return the nuber of blocks that were split. */
1994 flow_call_edges_add (blocks)
1998 int blocks_split = 0;
2002 /* Map bb indicies into basic block pointers since split_block
2003 will renumber the basic blocks. */
2005 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2009 for (i = 0; i < n_basic_blocks; i++)
2010 bbs[bb_num++] = BASIC_BLOCK (i);
2014 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2016 bbs[bb_num++] = BASIC_BLOCK (i);
2021 /* Now add fake edges to the function exit for any non constant
2022 calls since there is no way that we can determine if they will
2025 for (i = 0; i < bb_num; i++)
2027 basic_block bb = bbs[i];
2031 for (insn = bb->end; ; insn = prev_insn)
2033 prev_insn = PREV_INSN (insn);
2034 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2038 /* Note that the following may create a new basic block
2039 and renumber the existing basic blocks. */
2040 e = split_block (bb, insn);
2044 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2046 if (insn == bb->head)
2052 verify_flow_info ();
2055 return blocks_split;
2058 /* Delete all unreachable basic blocks. */
2061 delete_unreachable_blocks ()
2063 basic_block *worklist, *tos;
2068 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2070 /* Use basic_block->aux as a marker. Clear them all. */
2072 for (i = 0; i < n; ++i)
2073 BASIC_BLOCK (i)->aux = NULL;
2075 /* Add our starting points to the worklist. Almost always there will
2076 be only one. It isn't inconcievable that we might one day directly
2077 support Fortran alternate entry points. */
2079 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2083 /* Mark the block with a handy non-null value. */
2087 /* Iterate: find everything reachable from what we've already seen. */
2089 while (tos != worklist)
2091 basic_block b = *--tos;
2093 for (e = b->succ; e; e = e->succ_next)
2101 /* Delete all unreachable basic blocks. Count down so that we
2102 don't interfere with the block renumbering that happens in
2103 flow_delete_block. */
2105 for (i = n - 1; i >= 0; --i)
2107 basic_block b = BASIC_BLOCK (i);
2110 /* This block was found. Tidy up the mark. */
2113 flow_delete_block (b);
2116 tidy_fallthru_edges ();
2121 /* Return true if NOTE is not one of the ones that must be kept paired,
2122 so that we may simply delete them. */
2125 can_delete_note_p (note)
2128 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2129 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2132 /* Unlink a chain of insns between START and FINISH, leaving notes
2133 that must be paired. */
2136 flow_delete_insn_chain (start, finish)
2139 /* Unchain the insns one by one. It would be quicker to delete all
2140 of these with a single unchaining, rather than one at a time, but
2141 we need to keep the NOTE's. */
2147 next = NEXT_INSN (start);
2148 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2150 else if (GET_CODE (start) == CODE_LABEL
2151 && ! can_delete_label_p (start))
2153 const char *name = LABEL_NAME (start);
2154 PUT_CODE (start, NOTE);
2155 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2156 NOTE_SOURCE_FILE (start) = name;
2159 next = flow_delete_insn (start);
2161 if (start == finish)
2167 /* Delete the insns in a (non-live) block. We physically delete every
2168 non-deleted-note insn, and update the flow graph appropriately.
2170 Return nonzero if we deleted an exception handler. */
2172 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2173 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2176 flow_delete_block (b)
2179 int deleted_handler = 0;
2182 /* If the head of this block is a CODE_LABEL, then it might be the
2183 label for an exception handler which can't be reached.
2185 We need to remove the label from the exception_handler_label list
2186 and remove the associated NOTE_INSN_EH_REGION_BEG and
2187 NOTE_INSN_EH_REGION_END notes. */
2191 never_reached_warning (insn);
2193 if (GET_CODE (insn) == CODE_LABEL)
2194 maybe_remove_eh_handler (insn);
2196 /* Include any jump table following the basic block. */
2198 if (GET_CODE (end) == JUMP_INSN
2199 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2200 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2201 && GET_CODE (tmp) == JUMP_INSN
2202 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2203 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2206 /* Include any barrier that may follow the basic block. */
2207 tmp = next_nonnote_insn (end);
2208 if (tmp && GET_CODE (tmp) == BARRIER)
2211 /* Selectively delete the entire chain. */
2212 flow_delete_insn_chain (insn, end);
2214 /* Remove the edges into and out of this block. Note that there may
2215 indeed be edges in, if we are removing an unreachable loop. */
2219 for (e = b->pred; e; e = next)
2221 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2224 next = e->pred_next;
2228 for (e = b->succ; e; e = next)
2230 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2233 next = e->succ_next;
2242 /* Remove the basic block from the array, and compact behind it. */
2245 return deleted_handler;
2248 /* Remove block B from the basic block array and compact behind it. */
2254 int i, n = n_basic_blocks;
2256 for (i = b->index; i + 1 < n; ++i)
2258 basic_block x = BASIC_BLOCK (i + 1);
2259 BASIC_BLOCK (i) = x;
2263 basic_block_info->num_elements--;
2267 /* Delete INSN by patching it out. Return the next insn. */
2270 flow_delete_insn (insn)
2273 rtx prev = PREV_INSN (insn);
2274 rtx next = NEXT_INSN (insn);
2277 PREV_INSN (insn) = NULL_RTX;
2278 NEXT_INSN (insn) = NULL_RTX;
2279 INSN_DELETED_P (insn) = 1;
2282 NEXT_INSN (prev) = next;
2284 PREV_INSN (next) = prev;
2286 set_last_insn (prev);
2288 if (GET_CODE (insn) == CODE_LABEL)
2289 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2291 /* If deleting a jump, decrement the use count of the label. Deleting
2292 the label itself should happen in the normal course of block merging. */
2293 if (GET_CODE (insn) == JUMP_INSN
2294 && JUMP_LABEL (insn)
2295 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2296 LABEL_NUSES (JUMP_LABEL (insn))--;
2298 /* Also if deleting an insn that references a label. */
2299 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2300 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2301 LABEL_NUSES (XEXP (note, 0))--;
2306 /* True if a given label can be deleted. */
2309 can_delete_label_p (label)
2314 if (LABEL_PRESERVE_P (label))
2317 for (x = forced_labels; x; x = XEXP (x, 1))
2318 if (label == XEXP (x, 0))
2320 for (x = label_value_list; x; x = XEXP (x, 1))
2321 if (label == XEXP (x, 0))
2323 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2324 if (label == XEXP (x, 0))
2327 /* User declared labels must be preserved. */
2328 if (LABEL_NAME (label) != 0)
2335 tail_recursion_label_p (label)
2340 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2341 if (label == XEXP (x, 0))
2347 /* Blocks A and B are to be merged into a single block A. The insns
2348 are already contiguous, hence `nomove'. */
2351 merge_blocks_nomove (a, b)
2355 rtx b_head, b_end, a_end;
2356 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2359 /* If there was a CODE_LABEL beginning B, delete it. */
2362 if (GET_CODE (b_head) == CODE_LABEL)
2364 /* Detect basic blocks with nothing but a label. This can happen
2365 in particular at the end of a function. */
2366 if (b_head == b_end)
2368 del_first = del_last = b_head;
2369 b_head = NEXT_INSN (b_head);
2372 /* Delete the basic block note. */
2373 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2375 if (b_head == b_end)
2380 b_head = NEXT_INSN (b_head);
2383 /* If there was a jump out of A, delete it. */
2385 if (GET_CODE (a_end) == JUMP_INSN)
2389 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2390 if (GET_CODE (prev) != NOTE
2391 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2398 /* If this was a conditional jump, we need to also delete
2399 the insn that set cc0. */
2400 if (prev && sets_cc0_p (prev))
2403 prev = prev_nonnote_insn (prev);
2412 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2413 del_first = NEXT_INSN (a_end);
2415 /* Delete everything marked above as well as crap that might be
2416 hanging out between the two blocks. */
2417 flow_delete_insn_chain (del_first, del_last);
2419 /* Normally there should only be one successor of A and that is B, but
2420 partway though the merge of blocks for conditional_execution we'll
2421 be merging a TEST block with THEN and ELSE successors. Free the
2422 whole lot of them and hope the caller knows what they're doing. */
2424 remove_edge (a->succ);
2426 /* Adjust the edges out of B for the new owner. */
2427 for (e = b->succ; e; e = e->succ_next)
2431 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2432 b->pred = b->succ = NULL;
2434 /* Reassociate the insns of B with A. */
2437 if (basic_block_for_insn)
2439 BLOCK_FOR_INSN (b_head) = a;
2440 while (b_head != b_end)
2442 b_head = NEXT_INSN (b_head);
2443 BLOCK_FOR_INSN (b_head) = a;
2453 /* Blocks A and B are to be merged into a single block. A has no incoming
2454 fallthru edge, so it can be moved before B without adding or modifying
2455 any jumps (aside from the jump from A to B). */
2458 merge_blocks_move_predecessor_nojumps (a, b)
2461 rtx start, end, barrier;
2467 barrier = next_nonnote_insn (end);
2468 if (GET_CODE (barrier) != BARRIER)
2470 flow_delete_insn (barrier);
2472 /* Move block and loop notes out of the chain so that we do not
2473 disturb their order.
2475 ??? A better solution would be to squeeze out all the non-nested notes
2476 and adjust the block trees appropriately. Even better would be to have
2477 a tighter connection between block trees and rtl so that this is not
2479 start = squeeze_notes (start, end);
2481 /* Scramble the insn chain. */
2482 if (end != PREV_INSN (b->head))
2483 reorder_insns (start, end, PREV_INSN (b->head));
2487 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2488 a->index, b->index);
2491 /* Swap the records for the two blocks around. Although we are deleting B,
2492 A is now where B was and we want to compact the BB array from where
2494 BASIC_BLOCK (a->index) = b;
2495 BASIC_BLOCK (b->index) = a;
2497 a->index = b->index;
2500 /* Now blocks A and B are contiguous. Merge them. */
2501 merge_blocks_nomove (a, b);
2506 /* Blocks A and B are to be merged into a single block. B has no outgoing
2507 fallthru edge, so it can be moved after A without adding or modifying
2508 any jumps (aside from the jump from A to B). */
2511 merge_blocks_move_successor_nojumps (a, b)
2514 rtx start, end, barrier;
2518 barrier = NEXT_INSN (end);
2520 /* Recognize a jump table following block B. */
2521 if (GET_CODE (barrier) == CODE_LABEL
2522 && NEXT_INSN (barrier)
2523 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2524 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2525 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2527 end = NEXT_INSN (barrier);
2528 barrier = NEXT_INSN (end);
2531 /* There had better have been a barrier there. Delete it. */
2532 if (GET_CODE (barrier) != BARRIER)
2534 flow_delete_insn (barrier);
2536 /* Move block and loop notes out of the chain so that we do not
2537 disturb their order.
2539 ??? A better solution would be to squeeze out all the non-nested notes
2540 and adjust the block trees appropriately. Even better would be to have
2541 a tighter connection between block trees and rtl so that this is not
2543 start = squeeze_notes (start, end);
2545 /* Scramble the insn chain. */
2546 reorder_insns (start, end, a->end);
2548 /* Now blocks A and B are contiguous. Merge them. */
2549 merge_blocks_nomove (a, b);
2553 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2554 b->index, a->index);
2560 /* Attempt to merge basic blocks that are potentially non-adjacent.
2561 Return true iff the attempt succeeded. */
2564 merge_blocks (e, b, c)
2568 /* If C has a tail recursion label, do not merge. There is no
2569 edge recorded from the call_placeholder back to this label, as
2570 that would make optimize_sibling_and_tail_recursive_calls more
2571 complex for no gain. */
2572 if (GET_CODE (c->head) == CODE_LABEL
2573 && tail_recursion_label_p (c->head))
2576 /* If B has a fallthru edge to C, no need to move anything. */
2577 if (e->flags & EDGE_FALLTHRU)
2579 merge_blocks_nomove (b, c);
2583 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2584 b->index, c->index);
2592 int c_has_outgoing_fallthru;
2593 int b_has_incoming_fallthru;
2595 /* We must make sure to not munge nesting of exception regions,
2596 lexical blocks, and loop notes.
2598 The first is taken care of by requiring that the active eh
2599 region at the end of one block always matches the active eh
2600 region at the beginning of the next block.
2602 The later two are taken care of by squeezing out all the notes. */
2604 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2605 executed and we may want to treat blocks which have two out
2606 edges, one normal, one abnormal as only having one edge for
2607 block merging purposes. */
2609 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2610 if (tmp_edge->flags & EDGE_FALLTHRU)
2612 c_has_outgoing_fallthru = (tmp_edge != NULL);
2614 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2615 if (tmp_edge->flags & EDGE_FALLTHRU)
2617 b_has_incoming_fallthru = (tmp_edge != NULL);
2619 /* If B does not have an incoming fallthru, then it can be moved
2620 immediately before C without introducing or modifying jumps.
2621 C cannot be the first block, so we do not have to worry about
2622 accessing a non-existent block. */
2623 if (! b_has_incoming_fallthru)
2624 return merge_blocks_move_predecessor_nojumps (b, c);
2626 /* Otherwise, we're going to try to move C after B. If C does
2627 not have an outgoing fallthru, then it can be moved
2628 immediately after B without introducing or modifying jumps. */
2629 if (! c_has_outgoing_fallthru)
2630 return merge_blocks_move_successor_nojumps (b, c);
2632 /* Otherwise, we'll need to insert an extra jump, and possibly
2633 a new block to contain it. */
2634 /* ??? Not implemented yet. */
2640 /* Top level driver for merge_blocks. */
2647 /* Attempt to merge blocks as made possible by edge removal. If a block
2648 has only one successor, and the successor has only one predecessor,
2649 they may be combined. */
2651 for (i = 0; i < n_basic_blocks;)
2653 basic_block c, b = BASIC_BLOCK (i);
2656 /* A loop because chains of blocks might be combineable. */
2657 while ((s = b->succ) != NULL
2658 && s->succ_next == NULL
2659 && (s->flags & EDGE_EH) == 0
2660 && (c = s->dest) != EXIT_BLOCK_PTR
2661 && c->pred->pred_next == NULL
2662 /* If the jump insn has side effects, we can't kill the edge. */
2663 && (GET_CODE (b->end) != JUMP_INSN
2664 || onlyjump_p (b->end))
2665 && merge_blocks (s, b, c))
2668 /* Don't get confused by the index shift caused by deleting blocks. */
2673 /* The given edge should potentially be a fallthru edge. If that is in
2674 fact true, delete the jump and barriers that are in the way. */
2677 tidy_fallthru_edge (e, b, c)
2683 /* ??? In a late-running flow pass, other folks may have deleted basic
2684 blocks by nopping out blocks, leaving multiple BARRIERs between here
2685 and the target label. They ought to be chastized and fixed.
2687 We can also wind up with a sequence of undeletable labels between
2688 one block and the next.
2690 So search through a sequence of barriers, labels, and notes for
2691 the head of block C and assert that we really do fall through. */
2693 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
2696 /* Remove what will soon cease being the jump insn from the source block.
2697 If block B consisted only of this single jump, turn it into a deleted
2700 if (GET_CODE (q) == JUMP_INSN
2702 && (any_uncondjump_p (q)
2703 || (b->succ == e && e->succ_next == NULL)))
2706 /* If this was a conditional jump, we need to also delete
2707 the insn that set cc0. */
2708 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
2715 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
2716 NOTE_SOURCE_FILE (q) = 0;
2722 /* We don't want a block to end on a line-number note since that has
2723 the potential of changing the code between -g and not -g. */
2724 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
2731 /* Selectively unlink the sequence. */
2732 if (q != PREV_INSN (c->head))
2733 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
2735 e->flags |= EDGE_FALLTHRU;
2738 /* Fix up edges that now fall through, or rather should now fall through
2739 but previously required a jump around now deleted blocks. Simplify
2740 the search by only examining blocks numerically adjacent, since this
2741 is how find_basic_blocks created them. */
2744 tidy_fallthru_edges ()
2748 for (i = 1; i < n_basic_blocks; ++i)
2750 basic_block b = BASIC_BLOCK (i - 1);
2751 basic_block c = BASIC_BLOCK (i);
2754 /* We care about simple conditional or unconditional jumps with
2757 If we had a conditional branch to the next instruction when
2758 find_basic_blocks was called, then there will only be one
2759 out edge for the block which ended with the conditional
2760 branch (since we do not create duplicate edges).
2762 Furthermore, the edge will be marked as a fallthru because we
2763 merge the flags for the duplicate edges. So we do not want to
2764 check that the edge is not a FALLTHRU edge. */
2765 if ((s = b->succ) != NULL
2766 && ! (s->flags & EDGE_COMPLEX)
2767 && s->succ_next == NULL
2769 /* If the jump insn has side effects, we can't tidy the edge. */
2770 && (GET_CODE (b->end) != JUMP_INSN
2771 || onlyjump_p (b->end)))
2772 tidy_fallthru_edge (s, b, c);
2776 /* Perform data flow analysis.
2777 F is the first insn of the function; FLAGS is a set of PROP_* flags
2778 to be used in accumulating flow info. */
2781 life_analysis (f, file, flags)
2786 #ifdef ELIMINABLE_REGS
2788 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
2791 /* Record which registers will be eliminated. We use this in
2794 CLEAR_HARD_REG_SET (elim_reg_set);
2796 #ifdef ELIMINABLE_REGS
2797 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
2798 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
2800 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
2804 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
2806 /* The post-reload life analysis have (on a global basis) the same
2807 registers live as was computed by reload itself. elimination
2808 Otherwise offsets and such may be incorrect.
2810 Reload will make some registers as live even though they do not
2813 We don't want to create new auto-incs after reload, since they
2814 are unlikely to be useful and can cause problems with shared
2816 if (reload_completed)
2817 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
2819 /* We want alias analysis information for local dead store elimination. */
2820 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2821 init_alias_analysis ();
2823 /* Always remove no-op moves. Do this before other processing so
2824 that we don't have to keep re-scanning them. */
2825 delete_noop_moves (f);
2827 /* Some targets can emit simpler epilogues if they know that sp was
2828 not ever modified during the function. After reload, of course,
2829 we've already emitted the epilogue so there's no sense searching. */
2830 if (! reload_completed)
2831 notice_stack_pointer_modification (f);
2833 /* Allocate and zero out data structures that will record the
2834 data from lifetime analysis. */
2835 allocate_reg_life_data ();
2836 allocate_bb_life_data ();
2838 /* Find the set of registers live on function exit. */
2839 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
2841 /* "Update" life info from zero. It'd be nice to begin the
2842 relaxation with just the exit and noreturn blocks, but that set
2843 is not immediately handy. */
2845 if (flags & PROP_REG_INFO)
2846 memset (regs_ever_live, 0, sizeof (regs_ever_live));
2847 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
2850 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2851 end_alias_analysis ();
2854 dump_flow_info (file);
2856 free_basic_block_vars (1);
2858 #ifdef ENABLE_CHECKING
2862 /* Search for any REG_LABEL notes whih reference deleted labels. */
2863 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2865 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
2867 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
2874 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2875 Search for REGNO. If found, abort if it is not wider than word_mode. */
2878 verify_wide_reg_1 (px, pregno)
2883 unsigned int regno = *(int *) pregno;
2885 if (GET_CODE (x) == REG && REGNO (x) == regno)
2887 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
2894 /* A subroutine of verify_local_live_at_start. Search through insns
2895 between HEAD and END looking for register REGNO. */
2898 verify_wide_reg (regno, head, end)
2905 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
2909 head = NEXT_INSN (head);
2912 /* We didn't find the register at all. Something's way screwy. */
2914 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
2915 print_rtl_and_abort ();
2918 /* A subroutine of update_life_info. Verify that there are no untoward
2919 changes in live_at_start during a local update. */
2922 verify_local_live_at_start (new_live_at_start, bb)
2923 regset new_live_at_start;
2926 if (reload_completed)
2928 /* After reload, there are no pseudos, nor subregs of multi-word
2929 registers. The regsets should exactly match. */
2930 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
2934 fprintf (rtl_dump_file,
2935 "live_at_start mismatch in bb %d, aborting\n",
2937 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
2938 debug_bitmap_file (rtl_dump_file, new_live_at_start);
2940 print_rtl_and_abort ();
2947 /* Find the set of changed registers. */
2948 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
2950 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
2952 /* No registers should die. */
2953 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
2956 fprintf (rtl_dump_file,
2957 "Register %d died unexpectedly in block %d\n", i,
2959 print_rtl_and_abort ();
2962 /* Verify that the now-live register is wider than word_mode. */
2963 verify_wide_reg (i, bb->head, bb->end);
2968 /* Updates life information starting with the basic blocks set in BLOCKS.
2969 If BLOCKS is null, consider it to be the universal set.
2971 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
2972 we are only expecting local modifications to basic blocks. If we find
2973 extra registers live at the beginning of a block, then we either killed
2974 useful data, or we have a broken split that wants data not provided.
2975 If we find registers removed from live_at_start, that means we have
2976 a broken peephole that is killing a register it shouldn't.
2978 ??? This is not true in one situation -- when a pre-reload splitter
2979 generates subregs of a multi-word pseudo, current life analysis will
2980 lose the kill. So we _can_ have a pseudo go live. How irritating.
2982 Including PROP_REG_INFO does not properly refresh regs_ever_live
2983 unless the caller resets it to zero. */
2986 update_life_info (blocks, extent, prop_flags)
2988 enum update_life_extent extent;
2992 regset_head tmp_head;
2995 tmp = INITIALIZE_REG_SET (tmp_head);
2997 /* For a global update, we go through the relaxation process again. */
2998 if (extent != UPDATE_LIFE_LOCAL)
3000 calculate_global_regs_live (blocks, blocks,
3001 prop_flags & PROP_SCAN_DEAD_CODE);
3003 /* If asked, remove notes from the blocks we'll update. */
3004 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
3005 count_or_remove_death_notes (blocks, 1);
3010 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
3012 basic_block bb = BASIC_BLOCK (i);
3014 COPY_REG_SET (tmp, bb->global_live_at_end);
3015 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3017 if (extent == UPDATE_LIFE_LOCAL)
3018 verify_local_live_at_start (tmp, bb);
3023 for (i = n_basic_blocks - 1; i >= 0; --i)
3025 basic_block bb = BASIC_BLOCK (i);
3027 COPY_REG_SET (tmp, bb->global_live_at_end);
3028 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3030 if (extent == UPDATE_LIFE_LOCAL)
3031 verify_local_live_at_start (tmp, bb);
3037 if (prop_flags & PROP_REG_INFO)
3039 /* The only pseudos that are live at the beginning of the function
3040 are those that were not set anywhere in the function. local-alloc
3041 doesn't know how to handle these correctly, so mark them as not
3042 local to any one basic block. */
3043 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
3044 FIRST_PSEUDO_REGISTER, i,
3045 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
3047 /* We have a problem with any pseudoreg that lives across the setjmp.
3048 ANSI says that if a user variable does not change in value between
3049 the setjmp and the longjmp, then the longjmp preserves it. This
3050 includes longjmp from a place where the pseudo appears dead.
3051 (In principle, the value still exists if it is in scope.)
3052 If the pseudo goes in a hard reg, some other value may occupy
3053 that hard reg where this pseudo is dead, thus clobbering the pseudo.
3054 Conclusion: such a pseudo must not go in a hard reg. */
3055 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
3056 FIRST_PSEUDO_REGISTER, i,
3058 if (regno_reg_rtx[i] != 0)
3060 REG_LIVE_LENGTH (i) = -1;
3061 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3067 /* Free the variables allocated by find_basic_blocks.
3069 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
3072 free_basic_block_vars (keep_head_end_p)
3073 int keep_head_end_p;
3075 if (basic_block_for_insn)
3077 VARRAY_FREE (basic_block_for_insn);
3078 basic_block_for_insn = NULL;
3081 if (! keep_head_end_p)
3084 VARRAY_FREE (basic_block_info);
3087 ENTRY_BLOCK_PTR->aux = NULL;
3088 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
3089 EXIT_BLOCK_PTR->aux = NULL;
3090 EXIT_BLOCK_PTR->global_live_at_start = NULL;
3094 /* Return nonzero if an insn consists only of SETs, each of which only sets a
3101 rtx pat = PATTERN (insn);
3103 /* Insns carrying these notes are useful later on. */
3104 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
3107 if (GET_CODE (pat) == SET && set_noop_p (pat))
3110 if (GET_CODE (pat) == PARALLEL)
3113 /* If nothing but SETs of registers to themselves,
3114 this insn can also be deleted. */
3115 for (i = 0; i < XVECLEN (pat, 0); i++)
3117 rtx tem = XVECEXP (pat, 0, i);
3119 if (GET_CODE (tem) == USE
3120 || GET_CODE (tem) == CLOBBER)
3123 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
3132 /* Delete any insns that copy a register to itself. */
3135 delete_noop_moves (f)
3139 for (insn = f; insn; insn = NEXT_INSN (insn))
3141 if (GET_CODE (insn) == INSN && noop_move_p (insn))
3143 PUT_CODE (insn, NOTE);
3144 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3145 NOTE_SOURCE_FILE (insn) = 0;
3150 /* Determine if the stack pointer is constant over the life of the function.
3151 Only useful before prologues have been emitted. */
3154 notice_stack_pointer_modification_1 (x, pat, data)
3156 rtx pat ATTRIBUTE_UNUSED;
3157 void *data ATTRIBUTE_UNUSED;
3159 if (x == stack_pointer_rtx
3160 /* The stack pointer is only modified indirectly as the result
3161 of a push until later in flow. See the comments in rtl.texi
3162 regarding Embedded Side-Effects on Addresses. */
3163 || (GET_CODE (x) == MEM
3164 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
3165 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
3166 current_function_sp_is_unchanging = 0;
3170 notice_stack_pointer_modification (f)
3175 /* Assume that the stack pointer is unchanging if alloca hasn't
3177 current_function_sp_is_unchanging = !current_function_calls_alloca;
3178 if (! current_function_sp_is_unchanging)
3181 for (insn = f; insn; insn = NEXT_INSN (insn))
3185 /* Check if insn modifies the stack pointer. */
3186 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
3188 if (! current_function_sp_is_unchanging)
3194 /* Mark a register in SET. Hard registers in large modes get all
3195 of their component registers set as well. */
3198 mark_reg (reg, xset)
3202 regset set = (regset) xset;
3203 int regno = REGNO (reg);
3205 if (GET_MODE (reg) == BLKmode)
3208 SET_REGNO_REG_SET (set, regno);
3209 if (regno < FIRST_PSEUDO_REGISTER)
3211 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3213 SET_REGNO_REG_SET (set, regno + n);
3217 /* Mark those regs which are needed at the end of the function as live
3218 at the end of the last basic block. */
3221 mark_regs_live_at_end (set)
3226 /* If exiting needs the right stack value, consider the stack pointer
3227 live at the end of the function. */
3228 if ((HAVE_epilogue && reload_completed)
3229 || ! EXIT_IGNORE_STACK
3230 || (! FRAME_POINTER_REQUIRED
3231 && ! current_function_calls_alloca
3232 && flag_omit_frame_pointer)
3233 || current_function_sp_is_unchanging)
3235 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
3238 /* Mark the frame pointer if needed at the end of the function. If
3239 we end up eliminating it, it will be removed from the live list
3240 of each basic block by reload. */
3242 if (! reload_completed || frame_pointer_needed)
3244 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
3245 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3246 /* If they are different, also mark the hard frame pointer as live. */
3247 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
3248 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
3252 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
3253 /* Many architectures have a GP register even without flag_pic.
3254 Assume the pic register is not in use, or will be handled by
3255 other means, if it is not fixed. */
3256 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3257 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3258 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
3261 /* Mark all global registers, and all registers used by the epilogue
3262 as being live at the end of the function since they may be
3263 referenced by our caller. */
3264 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3265 if (global_regs[i] || EPILOGUE_USES (i))
3266 SET_REGNO_REG_SET (set, i);
3268 if (HAVE_epilogue && reload_completed)
3270 /* Mark all call-saved registers that we actually used. */
3271 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3272 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
3273 SET_REGNO_REG_SET (set, i);
3276 #ifdef EH_RETURN_DATA_REGNO
3277 /* Mark the registers that will contain data for the handler. */
3278 if (reload_completed && current_function_calls_eh_return)
3281 unsigned regno = EH_RETURN_DATA_REGNO(i);
3282 if (regno == INVALID_REGNUM)
3284 SET_REGNO_REG_SET (set, regno);
3287 #ifdef EH_RETURN_STACKADJ_RTX
3288 if ((! HAVE_epilogue || ! reload_completed)
3289 && current_function_calls_eh_return)
3291 rtx tmp = EH_RETURN_STACKADJ_RTX;
3292 if (tmp && REG_P (tmp))
3293 mark_reg (tmp, set);
3296 #ifdef EH_RETURN_HANDLER_RTX
3297 if ((! HAVE_epilogue || ! reload_completed)
3298 && current_function_calls_eh_return)
3300 rtx tmp = EH_RETURN_HANDLER_RTX;
3301 if (tmp && REG_P (tmp))
3302 mark_reg (tmp, set);
3306 /* Mark function return value. */
3307 diddle_return_value (mark_reg, set);
3310 /* Callback function for for_each_successor_phi. DATA is a regset.
3311 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3312 INSN, in the regset. */
3315 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
3316 rtx insn ATTRIBUTE_UNUSED;
3317 int dest_regno ATTRIBUTE_UNUSED;
3321 regset live = (regset) data;
3322 SET_REGNO_REG_SET (live, src_regno);
3326 /* Propagate global life info around the graph of basic blocks. Begin
3327 considering blocks with their corresponding bit set in BLOCKS_IN.
3328 If BLOCKS_IN is null, consider it the universal set.
3330 BLOCKS_OUT is set for every block that was changed. */
3333 calculate_global_regs_live (blocks_in, blocks_out, flags)
3334 sbitmap blocks_in, blocks_out;
3337 basic_block *queue, *qhead, *qtail, *qend;
3338 regset tmp, new_live_at_end, call_used;
3339 regset_head tmp_head, call_used_head;
3340 regset_head new_live_at_end_head;
3343 tmp = INITIALIZE_REG_SET (tmp_head);
3344 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
3345 call_used = INITIALIZE_REG_SET (call_used_head);
3347 /* Inconveniently, this is only redily available in hard reg set form. */
3348 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3349 if (call_used_regs[i])
3350 SET_REGNO_REG_SET (call_used, i);
3352 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3353 because the `head == tail' style test for an empty queue doesn't
3354 work with a full queue. */
3355 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3357 qhead = qend = queue + n_basic_blocks + 2;
3359 /* Queue the blocks set in the initial mask. Do this in reverse block
3360 number order so that we are more likely for the first round to do
3361 useful work. We use AUX non-null to flag that the block is queued. */
3364 /* Clear out the garbage that might be hanging out in bb->aux. */
3365 for (i = n_basic_blocks - 1; i >= 0; --i)
3366 BASIC_BLOCK (i)->aux = NULL;
3368 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3370 basic_block bb = BASIC_BLOCK (i);
3377 for (i = 0; i < n_basic_blocks; ++i)
3379 basic_block bb = BASIC_BLOCK (i);
3386 sbitmap_zero (blocks_out);
3388 while (qhead != qtail)
3390 int rescan, changed;
3399 /* Begin by propogating live_at_start from the successor blocks. */
3400 CLEAR_REG_SET (new_live_at_end);
3401 for (e = bb->succ; e; e = e->succ_next)
3403 basic_block sb = e->dest;
3405 /* Call-clobbered registers die across exception and call edges. */
3406 /* ??? Abnormal call edges ignored for the moment, as this gets
3407 confused by sibling call edges, which crashes reg-stack. */
3408 if (e->flags & EDGE_EH)
3410 bitmap_operation (tmp, sb->global_live_at_start,
3411 call_used, BITMAP_AND_COMPL);
3412 IOR_REG_SET (new_live_at_end, tmp);
3415 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3418 /* The all-important stack pointer must always be live. */
3419 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3421 /* Before reload, there are a few registers that must be forced
3422 live everywhere -- which might not already be the case for
3423 blocks within infinite loops. */
3424 if (! reload_completed)
3426 /* Any reference to any pseudo before reload is a potential
3427 reference of the frame pointer. */
3428 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3430 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3431 /* Pseudos with argument area equivalences may require
3432 reloading via the argument pointer. */
3433 if (fixed_regs[ARG_POINTER_REGNUM])
3434 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
3437 /* Any constant, or pseudo with constant equivalences, may
3438 require reloading from memory using the pic register. */
3439 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3440 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3441 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
3444 /* Regs used in phi nodes are not included in
3445 global_live_at_start, since they are live only along a
3446 particular edge. Set those regs that are live because of a
3447 phi node alternative corresponding to this particular block. */
3449 for_each_successor_phi (bb, &set_phi_alternative_reg,
3452 if (bb == ENTRY_BLOCK_PTR)
3454 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3458 /* On our first pass through this block, we'll go ahead and continue.
3459 Recognize first pass by local_set NULL. On subsequent passes, we
3460 get to skip out early if live_at_end wouldn't have changed. */
3462 if (bb->local_set == NULL)
3464 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3465 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3470 /* If any bits were removed from live_at_end, we'll have to
3471 rescan the block. This wouldn't be necessary if we had
3472 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3473 local_live is really dependent on live_at_end. */
3474 CLEAR_REG_SET (tmp);
3475 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3476 new_live_at_end, BITMAP_AND_COMPL);
3480 /* If any of the registers in the new live_at_end set are
3481 conditionally set in this basic block, we must rescan.
3482 This is because conditional lifetimes at the end of the
3483 block do not just take the live_at_end set into account,
3484 but also the liveness at the start of each successor
3485 block. We can miss changes in those sets if we only
3486 compare the new live_at_end against the previous one. */
3487 CLEAR_REG_SET (tmp);
3488 rescan = bitmap_operation (tmp, new_live_at_end,
3489 bb->cond_local_set, BITMAP_AND);
3494 /* Find the set of changed bits. Take this opportunity
3495 to notice that this set is empty and early out. */
3496 CLEAR_REG_SET (tmp);
3497 changed = bitmap_operation (tmp, bb->global_live_at_end,
3498 new_live_at_end, BITMAP_XOR);
3502 /* If any of the changed bits overlap with local_set,
3503 we'll have to rescan the block. Detect overlap by
3504 the AND with ~local_set turning off bits. */
3505 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3510 /* Let our caller know that BB changed enough to require its
3511 death notes updated. */
3513 SET_BIT (blocks_out, bb->index);
3517 /* Add to live_at_start the set of all registers in
3518 new_live_at_end that aren't in the old live_at_end. */
3520 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3522 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3524 changed = bitmap_operation (bb->global_live_at_start,
3525 bb->global_live_at_start,
3532 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3534 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3535 into live_at_start. */
3536 propagate_block (bb, new_live_at_end, bb->local_set,
3537 bb->cond_local_set, flags);
3539 /* If live_at start didn't change, no need to go farther. */
3540 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3543 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3546 /* Queue all predecessors of BB so that we may re-examine
3547 their live_at_end. */
3548 for (e = bb->pred; e; e = e->pred_next)
3550 basic_block pb = e->src;
3551 if (pb->aux == NULL)
3562 FREE_REG_SET (new_live_at_end);
3563 FREE_REG_SET (call_used);
3567 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3569 basic_block bb = BASIC_BLOCK (i);
3570 FREE_REG_SET (bb->local_set);
3571 FREE_REG_SET (bb->cond_local_set);
3576 for (i = n_basic_blocks - 1; i >= 0; --i)
3578 basic_block bb = BASIC_BLOCK (i);
3579 FREE_REG_SET (bb->local_set);
3580 FREE_REG_SET (bb->cond_local_set);
3587 /* Subroutines of life analysis. */
3589 /* Allocate the permanent data structures that represent the results
3590 of life analysis. Not static since used also for stupid life analysis. */
3593 allocate_bb_life_data ()
3597 for (i = 0; i < n_basic_blocks; i++)
3599 basic_block bb = BASIC_BLOCK (i);
3601 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3602 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3605 ENTRY_BLOCK_PTR->global_live_at_end
3606 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3607 EXIT_BLOCK_PTR->global_live_at_start
3608 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3610 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3614 allocate_reg_life_data ()
3618 max_regno = max_reg_num ();
3620 /* Recalculate the register space, in case it has grown. Old style
3621 vector oriented regsets would set regset_{size,bytes} here also. */
3622 allocate_reg_info (max_regno, FALSE, FALSE);
3624 /* Reset all the data we'll collect in propagate_block and its
3626 for (i = 0; i < max_regno; i++)
3630 REG_N_DEATHS (i) = 0;
3631 REG_N_CALLS_CROSSED (i) = 0;
3632 REG_LIVE_LENGTH (i) = 0;
3633 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3637 /* Delete dead instructions for propagate_block. */
3640 propagate_block_delete_insn (bb, insn)
3644 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3646 /* If the insn referred to a label, and that label was attached to
3647 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3648 pretty much mandatory to delete it, because the ADDR_VEC may be
3649 referencing labels that no longer exist.
3651 INSN may reference a deleted label, particularly when a jump
3652 table has been optimized into a direct jump. There's no
3653 real good way to fix up the reference to the deleted label
3654 when the label is deleted, so we just allow it here.
3656 After dead code elimination is complete, we do search for
3657 any REG_LABEL notes which reference deleted labels as a
3660 if (inote && GET_CODE (inote) == CODE_LABEL)
3662 rtx label = XEXP (inote, 0);
3665 /* The label may be forced if it has been put in the constant
3666 pool. If that is the only use we must discard the table
3667 jump following it, but not the label itself. */
3668 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
3669 && (next = next_nonnote_insn (label)) != NULL
3670 && GET_CODE (next) == JUMP_INSN
3671 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3672 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3674 rtx pat = PATTERN (next);
3675 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3676 int len = XVECLEN (pat, diff_vec_p);
3679 for (i = 0; i < len; i++)
3680 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3682 flow_delete_insn (next);
3686 if (bb->end == insn)
3687 bb->end = PREV_INSN (insn);
3688 flow_delete_insn (insn);
3691 /* Delete dead libcalls for propagate_block. Return the insn
3692 before the libcall. */
3695 propagate_block_delete_libcall (bb, insn, note)
3699 rtx first = XEXP (note, 0);
3700 rtx before = PREV_INSN (first);
3702 if (insn == bb->end)
3705 flow_delete_insn_chain (first, insn);
3709 /* Update the life-status of regs for one insn. Return the previous insn. */
3712 propagate_one_insn (pbi, insn)
3713 struct propagate_block_info *pbi;
3716 rtx prev = PREV_INSN (insn);
3717 int flags = pbi->flags;
3718 int insn_is_dead = 0;
3719 int libcall_is_dead = 0;
3723 if (! INSN_P (insn))
3726 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3727 if (flags & PROP_SCAN_DEAD_CODE)
3729 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
3730 libcall_is_dead = (insn_is_dead && note != 0
3731 && libcall_dead_p (pbi, note, insn));
3734 /* If an instruction consists of just dead store(s) on final pass,
3736 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3738 /* If we're trying to delete a prologue or epilogue instruction
3739 that isn't flagged as possibly being dead, something is wrong.
3740 But if we are keeping the stack pointer depressed, we might well
3741 be deleting insns that are used to compute the amount to update
3742 it by, so they are fine. */
3743 if (reload_completed
3744 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
3745 && (TYPE_RETURNS_STACK_DEPRESSED
3746 (TREE_TYPE (current_function_decl))))
3747 && (((HAVE_epilogue || HAVE_prologue)
3748 && prologue_epilogue_contains (insn))
3749 || (HAVE_sibcall_epilogue
3750 && sibcall_epilogue_contains (insn)))
3751 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
3754 /* Record sets. Do this even for dead instructions, since they
3755 would have killed the values if they hadn't been deleted. */
3756 mark_set_regs (pbi, PATTERN (insn), insn);
3758 /* CC0 is now known to be dead. Either this insn used it,
3759 in which case it doesn't anymore, or clobbered it,
3760 so the next insn can't use it. */
3763 if (libcall_is_dead)
3764 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
3766 propagate_block_delete_insn (pbi->bb, insn);
3771 /* See if this is an increment or decrement that can be merged into
3772 a following memory address. */
3775 register rtx x = single_set (insn);
3777 /* Does this instruction increment or decrement a register? */
3778 if ((flags & PROP_AUTOINC)
3780 && GET_CODE (SET_DEST (x)) == REG
3781 && (GET_CODE (SET_SRC (x)) == PLUS
3782 || GET_CODE (SET_SRC (x)) == MINUS)
3783 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3784 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3785 /* Ok, look for a following memory ref we can combine with.
3786 If one is found, change the memory ref to a PRE_INC
3787 or PRE_DEC, cancel this insn, and return 1.
3788 Return 0 if nothing has been done. */
3789 && try_pre_increment_1 (pbi, insn))
3792 #endif /* AUTO_INC_DEC */
3794 CLEAR_REG_SET (pbi->new_set);
3796 /* If this is not the final pass, and this insn is copying the value of
3797 a library call and it's dead, don't scan the insns that perform the
3798 library call, so that the call's arguments are not marked live. */
3799 if (libcall_is_dead)
3801 /* Record the death of the dest reg. */
3802 mark_set_regs (pbi, PATTERN (insn), insn);
3804 insn = XEXP (note, 0);
3805 return PREV_INSN (insn);
3807 else if (GET_CODE (PATTERN (insn)) == SET
3808 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3809 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3810 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3811 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3812 /* We have an insn to pop a constant amount off the stack.
3813 (Such insns use PLUS regardless of the direction of the stack,
3814 and any insn to adjust the stack by a constant is always a pop.)
3815 These insns, if not dead stores, have no effect on life. */
3819 /* Any regs live at the time of a call instruction must not go
3820 in a register clobbered by calls. Find all regs now live and
3821 record this for them. */
3823 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
3824 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3825 { REG_N_CALLS_CROSSED (i)++; });
3827 /* Record sets. Do this even for dead instructions, since they
3828 would have killed the values if they hadn't been deleted. */
3829 mark_set_regs (pbi, PATTERN (insn), insn);
3831 if (GET_CODE (insn) == CALL_INSN)
3837 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3838 cond = COND_EXEC_TEST (PATTERN (insn));
3840 /* Non-constant calls clobber memory. */
3841 if (! CONST_CALL_P (insn))
3843 free_EXPR_LIST_list (&pbi->mem_set_list);
3844 pbi->mem_set_list_len = 0;
3847 /* There may be extra registers to be clobbered. */
3848 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3850 note = XEXP (note, 1))
3851 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
3852 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
3853 cond, insn, pbi->flags);
3855 /* Calls change all call-used and global registers. */
3856 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3857 if (call_used_regs[i] && ! global_regs[i]
3860 /* We do not want REG_UNUSED notes for these registers. */
3861 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
3863 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
3867 /* If an insn doesn't use CC0, it becomes dead since we assume
3868 that every insn clobbers it. So show it dead here;
3869 mark_used_regs will set it live if it is referenced. */
3874 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
3876 /* Sometimes we may have inserted something before INSN (such as a move)
3877 when we make an auto-inc. So ensure we will scan those insns. */
3879 prev = PREV_INSN (insn);
3882 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3888 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3889 cond = COND_EXEC_TEST (PATTERN (insn));
3891 /* Calls use their arguments. */
3892 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3894 note = XEXP (note, 1))
3895 if (GET_CODE (XEXP (note, 0)) == USE)
3896 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
3899 /* The stack ptr is used (honorarily) by a CALL insn. */
3900 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
3902 /* Calls may also reference any of the global registers,
3903 so they are made live. */
3904 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3906 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
3911 /* On final pass, update counts of how many insns in which each reg
3913 if (flags & PROP_REG_INFO)
3914 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3915 { REG_LIVE_LENGTH (i)++; });
3920 /* Initialize a propagate_block_info struct for public consumption.
3921 Note that the structure itself is opaque to this file, but that
3922 the user can use the regsets provided here. */
3924 struct propagate_block_info *
3925 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
3927 regset live, local_set, cond_local_set;
3930 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
3933 pbi->reg_live = live;
3934 pbi->mem_set_list = NULL_RTX;
3935 pbi->mem_set_list_len = 0;
3936 pbi->local_set = local_set;
3937 pbi->cond_local_set = cond_local_set;
3941 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3942 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
3944 pbi->reg_next_use = NULL;
3946 pbi->new_set = BITMAP_XMALLOC ();
3948 #ifdef HAVE_conditional_execution
3949 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
3950 free_reg_cond_life_info);
3951 pbi->reg_cond_reg = BITMAP_XMALLOC ();
3953 /* If this block ends in a conditional branch, for each register live
3954 from one side of the branch and not the other, record the register
3955 as conditionally dead. */
3956 if (GET_CODE (bb->end) == JUMP_INSN
3957 && any_condjump_p (bb->end))
3959 regset_head diff_head;
3960 regset diff = INITIALIZE_REG_SET (diff_head);
3961 basic_block bb_true, bb_false;
3962 rtx cond_true, cond_false, set_src;
3965 /* Identify the successor blocks. */
3966 bb_true = bb->succ->dest;
3967 if (bb->succ->succ_next != NULL)
3969 bb_false = bb->succ->succ_next->dest;
3971 if (bb->succ->flags & EDGE_FALLTHRU)
3973 basic_block t = bb_false;
3977 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
3982 /* This can happen with a conditional jump to the next insn. */
3983 if (JUMP_LABEL (bb->end) != bb_true->head)
3986 /* Simplest way to do nothing. */
3990 /* Extract the condition from the branch. */
3991 set_src = SET_SRC (pc_set (bb->end));
3992 cond_true = XEXP (set_src, 0);
3993 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
3994 GET_MODE (cond_true), XEXP (cond_true, 0),
3995 XEXP (cond_true, 1));
3996 if (GET_CODE (XEXP (set_src, 1)) == PC)
3999 cond_false = cond_true;
4003 /* Compute which register lead different lives in the successors. */
4004 if (bitmap_operation (diff, bb_true->global_live_at_start,
4005 bb_false->global_live_at_start, BITMAP_XOR))
4007 rtx reg = XEXP (cond_true, 0);
4009 if (GET_CODE (reg) == SUBREG)
4010 reg = SUBREG_REG (reg);
4012 if (GET_CODE (reg) != REG)
4015 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
4017 /* For each such register, mark it conditionally dead. */
4018 EXECUTE_IF_SET_IN_REG_SET
4021 struct reg_cond_life_info *rcli;
4024 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4026 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
4030 rcli->condition = cond;
4031 rcli->stores = const0_rtx;
4032 rcli->orig_condition = cond;
4034 splay_tree_insert (pbi->reg_cond_dead, i,
4035 (splay_tree_value) rcli);
4039 FREE_REG_SET (diff);
4043 /* If this block has no successors, any stores to the frame that aren't
4044 used later in the block are dead. So make a pass over the block
4045 recording any such that are made and show them dead at the end. We do
4046 a very conservative and simple job here. */
4048 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4049 && (TYPE_RETURNS_STACK_DEPRESSED
4050 (TREE_TYPE (current_function_decl))))
4051 && (flags & PROP_SCAN_DEAD_CODE)
4052 && (bb->succ == NULL
4053 || (bb->succ->succ_next == NULL
4054 && bb->succ->dest == EXIT_BLOCK_PTR
4055 && ! current_function_calls_eh_return)))
4058 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
4059 if (GET_CODE (insn) == INSN
4060 && (set = single_set (insn))
4061 && GET_CODE (SET_DEST (set)) == MEM)
4063 rtx mem = SET_DEST (set);
4064 rtx canon_mem = canon_rtx (mem);
4066 /* This optimization is performed by faking a store to the
4067 memory at the end of the block. This doesn't work for
4068 unchanging memories because multiple stores to unchanging
4069 memory is illegal and alias analysis doesn't consider it. */
4070 if (RTX_UNCHANGING_P (canon_mem))
4073 if (XEXP (canon_mem, 0) == frame_pointer_rtx
4074 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
4075 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
4076 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
4079 /* Store a copy of mem, otherwise the address may be scrogged
4080 by find_auto_inc. This matters because insn_dead_p uses
4081 an rtx_equal_p check to determine if two addresses are
4082 the same. This works before find_auto_inc, but fails
4083 after find_auto_inc, causing discrepencies between the
4084 set of live registers calculated during the
4085 calculate_global_regs_live phase and what actually exists
4086 after flow completes, leading to aborts. */
4087 if (flags & PROP_AUTOINC)
4088 mem = shallow_copy_rtx (mem);
4090 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
4091 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
4100 /* Release a propagate_block_info struct. */
4103 free_propagate_block_info (pbi)
4104 struct propagate_block_info *pbi;
4106 free_EXPR_LIST_list (&pbi->mem_set_list);
4108 BITMAP_XFREE (pbi->new_set);
4110 #ifdef HAVE_conditional_execution
4111 splay_tree_delete (pbi->reg_cond_dead);
4112 BITMAP_XFREE (pbi->reg_cond_reg);
4115 if (pbi->reg_next_use)
4116 free (pbi->reg_next_use);
4121 /* Compute the registers live at the beginning of a basic block BB from
4122 those live at the end.
4124 When called, REG_LIVE contains those live at the end. On return, it
4125 contains those live at the beginning.
4127 LOCAL_SET, if non-null, will be set with all registers killed
4128 unconditionally by this basic block.
4129 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
4130 killed conditionally by this basic block. If there is any unconditional
4131 set of a register, then the corresponding bit will be set in LOCAL_SET
4132 and cleared in COND_LOCAL_SET.
4133 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
4134 case, the resulting set will be equal to the union of the two sets that
4135 would otherwise be computed. */
4138 propagate_block (bb, live, local_set, cond_local_set, flags)
4142 regset cond_local_set;
4145 struct propagate_block_info *pbi;
4148 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
4150 if (flags & PROP_REG_INFO)
4154 /* Process the regs live at the end of the block.
4155 Mark them as not local to any one basic block. */
4156 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
4157 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4160 /* Scan the block an insn at a time from end to beginning. */
4162 for (insn = bb->end;; insn = prev)
4164 /* If this is a call to `setjmp' et al, warn if any
4165 non-volatile datum is live. */
4166 if ((flags & PROP_REG_INFO)
4167 && GET_CODE (insn) == NOTE
4168 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
4169 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
4171 prev = propagate_one_insn (pbi, insn);
4173 if (insn == bb->head)
4177 free_propagate_block_info (pbi);
4180 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
4181 (SET expressions whose destinations are registers dead after the insn).
4182 NEEDED is the regset that says which regs are alive after the insn.
4184 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
4186 If X is the entire body of an insn, NOTES contains the reg notes
4187 pertaining to the insn. */
4190 insn_dead_p (pbi, x, call_ok, notes)
4191 struct propagate_block_info *pbi;
4194 rtx notes ATTRIBUTE_UNUSED;
4196 enum rtx_code code = GET_CODE (x);
4199 /* If flow is invoked after reload, we must take existing AUTO_INC
4200 expresions into account. */
4201 if (reload_completed)
4203 for (; notes; notes = XEXP (notes, 1))
4205 if (REG_NOTE_KIND (notes) == REG_INC)
4207 int regno = REGNO (XEXP (notes, 0));
4209 /* Don't delete insns to set global regs. */
4210 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4211 || REGNO_REG_SET_P (pbi->reg_live, regno))
4218 /* If setting something that's a reg or part of one,
4219 see if that register's altered value will be live. */
4223 rtx r = SET_DEST (x);
4226 if (GET_CODE (r) == CC0)
4227 return ! pbi->cc0_live;
4230 /* A SET that is a subroutine call cannot be dead. */
4231 if (GET_CODE (SET_SRC (x)) == CALL)
4237 /* Don't eliminate loads from volatile memory or volatile asms. */
4238 else if (volatile_refs_p (SET_SRC (x)))
4241 if (GET_CODE (r) == MEM)
4245 if (MEM_VOLATILE_P (r))
4248 /* Walk the set of memory locations we are currently tracking
4249 and see if one is an identical match to this memory location.
4250 If so, this memory write is dead (remember, we're walking
4251 backwards from the end of the block to the start). Since
4252 rtx_equal_p does not check the alias set or flags, we also
4253 must have the potential for them to conflict (anti_dependence). */
4254 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
4255 if (anti_dependence (r, XEXP (temp, 0)))
4257 rtx mem = XEXP (temp, 0);
4259 if (rtx_equal_p (mem, r))
4262 /* Check if memory reference matches an auto increment. Only
4263 post increment/decrement or modify are valid. */
4264 if (GET_MODE (mem) == GET_MODE (r)
4265 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4266 || GET_CODE (XEXP (mem, 0)) == POST_INC
4267 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4268 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4269 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4276 while (GET_CODE (r) == SUBREG
4277 || GET_CODE (r) == STRICT_LOW_PART
4278 || GET_CODE (r) == ZERO_EXTRACT)
4281 if (GET_CODE (r) == REG)
4283 int regno = REGNO (r);
4286 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4289 /* If this is a hard register, verify that subsequent
4290 words are not needed. */
4291 if (regno < FIRST_PSEUDO_REGISTER)
4293 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4296 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4300 /* Don't delete insns to set global regs. */
4301 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4304 /* Make sure insns to set the stack pointer aren't deleted. */
4305 if (regno == STACK_POINTER_REGNUM)
4308 /* ??? These bits might be redundant with the force live bits
4309 in calculate_global_regs_live. We would delete from
4310 sequential sets; whether this actually affects real code
4311 for anything but the stack pointer I don't know. */
4312 /* Make sure insns to set the frame pointer aren't deleted. */
4313 if (regno == FRAME_POINTER_REGNUM
4314 && (! reload_completed || frame_pointer_needed))
4316 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4317 if (regno == HARD_FRAME_POINTER_REGNUM
4318 && (! reload_completed || frame_pointer_needed))
4322 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4323 /* Make sure insns to set arg pointer are never deleted
4324 (if the arg pointer isn't fixed, there will be a USE
4325 for it, so we can treat it normally). */
4326 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4330 /* Otherwise, the set is dead. */
4336 /* If performing several activities, insn is dead if each activity
4337 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4338 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4340 else if (code == PARALLEL)
4342 int i = XVECLEN (x, 0);
4344 for (i--; i >= 0; i--)
4345 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4346 && GET_CODE (XVECEXP (x, 0, i)) != USE
4347 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4353 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4354 is not necessarily true for hard registers. */
4355 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4356 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4357 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4360 /* We do not check other CLOBBER or USE here. An insn consisting of just
4361 a CLOBBER or just a USE should not be deleted. */
4365 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4366 return 1 if the entire library call is dead.
4367 This is true if INSN copies a register (hard or pseudo)
4368 and if the hard return reg of the call insn is dead.
4369 (The caller should have tested the destination of the SET inside
4370 INSN already for death.)
4372 If this insn doesn't just copy a register, then we don't
4373 have an ordinary libcall. In that case, cse could not have
4374 managed to substitute the source for the dest later on,
4375 so we can assume the libcall is dead.
4377 PBI is the block info giving pseudoregs live before this insn.
4378 NOTE is the REG_RETVAL note of the insn. */
4381 libcall_dead_p (pbi, note, insn)
4382 struct propagate_block_info *pbi;
4386 rtx x = single_set (insn);
4390 register rtx r = SET_SRC (x);
4391 if (GET_CODE (r) == REG)
4393 rtx call = XEXP (note, 0);
4397 /* Find the call insn. */
4398 while (call != insn && GET_CODE (call) != CALL_INSN)
4399 call = NEXT_INSN (call);
4401 /* If there is none, do nothing special,
4402 since ordinary death handling can understand these insns. */
4406 /* See if the hard reg holding the value is dead.
4407 If this is a PARALLEL, find the call within it. */
4408 call_pat = PATTERN (call);
4409 if (GET_CODE (call_pat) == PARALLEL)
4411 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4412 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4413 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4416 /* This may be a library call that is returning a value
4417 via invisible pointer. Do nothing special, since
4418 ordinary death handling can understand these insns. */
4422 call_pat = XVECEXP (call_pat, 0, i);
4425 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4431 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4432 live at function entry. Don't count global register variables, variables
4433 in registers that can be used for function arg passing, or variables in
4434 fixed hard registers. */
4437 regno_uninitialized (regno)
4440 if (n_basic_blocks == 0
4441 || (regno < FIRST_PSEUDO_REGISTER
4442 && (global_regs[regno]
4443 || fixed_regs[regno]
4444 || FUNCTION_ARG_REGNO_P (regno))))
4447 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
4450 /* 1 if register REGNO was alive at a place where `setjmp' was called
4451 and was set more than once or is an argument.
4452 Such regs may be clobbered by `longjmp'. */
4455 regno_clobbered_at_setjmp (regno)
4458 if (n_basic_blocks == 0)
4461 return ((REG_N_SETS (regno) > 1
4462 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
4463 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
4466 /* INSN references memory, possibly using autoincrement addressing modes.
4467 Find any entries on the mem_set_list that need to be invalidated due
4468 to an address change. */
4471 invalidate_mems_from_autoinc (pbi, insn)
4472 struct propagate_block_info *pbi;
4475 rtx note = REG_NOTES (insn);
4476 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
4478 if (REG_NOTE_KIND (note) == REG_INC)
4480 rtx temp = pbi->mem_set_list;
4481 rtx prev = NULL_RTX;
4486 next = XEXP (temp, 1);
4487 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
4489 /* Splice temp out of list. */
4491 XEXP (prev, 1) = next;
4493 pbi->mem_set_list = next;
4494 free_EXPR_LIST_node (temp);
4495 pbi->mem_set_list_len--;
4505 /* EXP is either a MEM or a REG. Remove any dependant entries
4506 from pbi->mem_set_list. */
4509 invalidate_mems_from_set (pbi, exp)
4510 struct propagate_block_info *pbi;
4513 rtx temp = pbi->mem_set_list;
4514 rtx prev = NULL_RTX;
4519 next = XEXP (temp, 1);
4520 if ((GET_CODE (exp) == MEM
4521 && output_dependence (XEXP (temp, 0), exp))
4522 || (GET_CODE (exp) == REG
4523 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
4525 /* Splice this entry out of the list. */
4527 XEXP (prev, 1) = next;
4529 pbi->mem_set_list = next;
4530 free_EXPR_LIST_node (temp);
4531 pbi->mem_set_list_len--;
4539 /* Process the registers that are set within X. Their bits are set to
4540 1 in the regset DEAD, because they are dead prior to this insn.
4542 If INSN is nonzero, it is the insn being processed.
4544 FLAGS is the set of operations to perform. */
4547 mark_set_regs (pbi, x, insn)
4548 struct propagate_block_info *pbi;
4551 rtx cond = NULL_RTX;
4556 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
4558 if (REG_NOTE_KIND (link) == REG_INC)
4559 mark_set_1 (pbi, SET, XEXP (link, 0),
4560 (GET_CODE (x) == COND_EXEC
4561 ? COND_EXEC_TEST (x) : NULL_RTX),
4565 switch (code = GET_CODE (x))
4569 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
4573 cond = COND_EXEC_TEST (x);
4574 x = COND_EXEC_CODE (x);
4580 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
4582 rtx sub = XVECEXP (x, 0, i);
4583 switch (code = GET_CODE (sub))
4586 if (cond != NULL_RTX)
4589 cond = COND_EXEC_TEST (sub);
4590 sub = COND_EXEC_CODE (sub);
4591 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
4597 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
4612 /* Process a single SET rtx, X. */
4615 mark_set_1 (pbi, code, reg, cond, insn, flags)
4616 struct propagate_block_info *pbi;
4618 rtx reg, cond, insn;
4621 int regno_first = -1, regno_last = -1;
4622 unsigned long not_dead = 0;
4625 /* Modifying just one hardware register of a multi-reg value or just a
4626 byte field of a register does not mean the value from before this insn
4627 is now dead. Of course, if it was dead after it's unused now. */
4629 switch (GET_CODE (reg))
4632 /* Some targets place small structures in registers for return values of
4633 functions. We have to detect this case specially here to get correct
4634 flow information. */
4635 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
4636 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
4637 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
4643 case STRICT_LOW_PART:
4644 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4646 reg = XEXP (reg, 0);
4647 while (GET_CODE (reg) == SUBREG
4648 || GET_CODE (reg) == ZERO_EXTRACT
4649 || GET_CODE (reg) == SIGN_EXTRACT
4650 || GET_CODE (reg) == STRICT_LOW_PART);
4651 if (GET_CODE (reg) == MEM)
4653 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
4657 regno_last = regno_first = REGNO (reg);
4658 if (regno_first < FIRST_PSEUDO_REGISTER)
4659 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
4663 if (GET_CODE (SUBREG_REG (reg)) == REG)
4665 enum machine_mode outer_mode = GET_MODE (reg);
4666 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
4668 /* Identify the range of registers affected. This is moderately
4669 tricky for hard registers. See alter_subreg. */
4671 regno_last = regno_first = REGNO (SUBREG_REG (reg));
4672 if (regno_first < FIRST_PSEUDO_REGISTER)
4674 regno_first += subreg_regno_offset (regno_first, inner_mode,
4677 regno_last = (regno_first
4678 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
4680 /* Since we've just adjusted the register number ranges, make
4681 sure REG matches. Otherwise some_was_live will be clear
4682 when it shouldn't have been, and we'll create incorrect
4683 REG_UNUSED notes. */
4684 reg = gen_rtx_REG (outer_mode, regno_first);
4688 /* If the number of words in the subreg is less than the number
4689 of words in the full register, we have a well-defined partial
4690 set. Otherwise the high bits are undefined.
4692 This is only really applicable to pseudos, since we just took
4693 care of multi-word hard registers. */
4694 if (((GET_MODE_SIZE (outer_mode)
4695 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
4696 < ((GET_MODE_SIZE (inner_mode)
4697 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
4698 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
4701 reg = SUBREG_REG (reg);
4705 reg = SUBREG_REG (reg);
4712 /* If this set is a MEM, then it kills any aliased writes.
4713 If this set is a REG, then it kills any MEMs which use the reg. */
4714 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4716 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
4717 invalidate_mems_from_set (pbi, reg);
4719 /* If the memory reference had embedded side effects (autoincrement
4720 address modes. Then we may need to kill some entries on the
4722 if (insn && GET_CODE (reg) == MEM)
4723 invalidate_mems_from_autoinc (pbi, insn);
4725 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
4726 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
4727 /* ??? With more effort we could track conditional memory life. */
4729 /* We do not know the size of a BLKmode store, so we do not track
4730 them for redundant store elimination. */
4731 && GET_MODE (reg) != BLKmode
4732 /* There are no REG_INC notes for SP, so we can't assume we'll see
4733 everything that invalidates it. To be safe, don't eliminate any
4734 stores though SP; none of them should be redundant anyway. */
4735 && ! reg_mentioned_p (stack_pointer_rtx, reg))
4738 /* Store a copy of mem, otherwise the address may be
4739 scrogged by find_auto_inc. */
4740 if (flags & PROP_AUTOINC)
4741 reg = shallow_copy_rtx (reg);
4743 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
4744 pbi->mem_set_list_len++;
4748 if (GET_CODE (reg) == REG
4749 && ! (regno_first == FRAME_POINTER_REGNUM
4750 && (! reload_completed || frame_pointer_needed))
4751 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4752 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
4753 && (! reload_completed || frame_pointer_needed))
4755 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4756 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
4760 int some_was_live = 0, some_was_dead = 0;
4762 for (i = regno_first; i <= regno_last; ++i)
4764 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
4767 /* Order of the set operation matters here since both
4768 sets may be the same. */
4769 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
4770 if (cond != NULL_RTX
4771 && ! REGNO_REG_SET_P (pbi->local_set, i))
4772 SET_REGNO_REG_SET (pbi->cond_local_set, i);
4774 SET_REGNO_REG_SET (pbi->local_set, i);
4776 if (code != CLOBBER)
4777 SET_REGNO_REG_SET (pbi->new_set, i);
4779 some_was_live |= needed_regno;
4780 some_was_dead |= ! needed_regno;
4783 #ifdef HAVE_conditional_execution
4784 /* Consider conditional death in deciding that the register needs
4786 if (some_was_live && ! not_dead
4787 /* The stack pointer is never dead. Well, not strictly true,
4788 but it's very difficult to tell from here. Hopefully
4789 combine_stack_adjustments will fix up the most egregious
4791 && regno_first != STACK_POINTER_REGNUM)
4793 for (i = regno_first; i <= regno_last; ++i)
4794 if (! mark_regno_cond_dead (pbi, i, cond))
4795 not_dead |= ((unsigned long) 1) << (i - regno_first);
4799 /* Additional data to record if this is the final pass. */
4800 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
4801 | PROP_DEATH_NOTES | PROP_AUTOINC))
4804 register int blocknum = pbi->bb->index;
4807 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4809 y = pbi->reg_next_use[regno_first];
4811 /* The next use is no longer next, since a store intervenes. */
4812 for (i = regno_first; i <= regno_last; ++i)
4813 pbi->reg_next_use[i] = 0;
4816 if (flags & PROP_REG_INFO)
4818 for (i = regno_first; i <= regno_last; ++i)
4820 /* Count (weighted) references, stores, etc. This counts a
4821 register twice if it is modified, but that is correct. */
4822 REG_N_SETS (i) += 1;
4823 REG_N_REFS (i) += (optimize_size ? 1
4824 : pbi->bb->loop_depth + 1);
4826 /* The insns where a reg is live are normally counted
4827 elsewhere, but we want the count to include the insn
4828 where the reg is set, and the normal counting mechanism
4829 would not count it. */
4830 REG_LIVE_LENGTH (i) += 1;
4833 /* If this is a hard reg, record this function uses the reg. */
4834 if (regno_first < FIRST_PSEUDO_REGISTER)
4836 for (i = regno_first; i <= regno_last; i++)
4837 regs_ever_live[i] = 1;
4841 /* Keep track of which basic blocks each reg appears in. */
4842 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
4843 REG_BASIC_BLOCK (regno_first) = blocknum;
4844 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
4845 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
4849 if (! some_was_dead)
4851 if (flags & PROP_LOG_LINKS)
4853 /* Make a logical link from the next following insn
4854 that uses this register, back to this insn.
4855 The following insns have already been processed.
4857 We don't build a LOG_LINK for hard registers containing
4858 in ASM_OPERANDs. If these registers get replaced,
4859 we might wind up changing the semantics of the insn,
4860 even if reload can make what appear to be valid
4861 assignments later. */
4862 if (y && (BLOCK_NUM (y) == blocknum)
4863 && (regno_first >= FIRST_PSEUDO_REGISTER
4864 || asm_noperands (PATTERN (y)) < 0))
4865 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4870 else if (! some_was_live)
4872 if (flags & PROP_REG_INFO)
4873 REG_N_DEATHS (regno_first) += 1;
4875 if (flags & PROP_DEATH_NOTES)
4877 /* Note that dead stores have already been deleted
4878 when possible. If we get here, we have found a
4879 dead store that cannot be eliminated (because the
4880 same insn does something useful). Indicate this
4881 by marking the reg being set as dying here. */
4883 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4888 if (flags & PROP_DEATH_NOTES)
4890 /* This is a case where we have a multi-word hard register
4891 and some, but not all, of the words of the register are
4892 needed in subsequent insns. Write REG_UNUSED notes
4893 for those parts that were not needed. This case should
4896 for (i = regno_first; i <= regno_last; ++i)
4897 if (! REGNO_REG_SET_P (pbi->reg_live, i))
4899 = alloc_EXPR_LIST (REG_UNUSED,
4900 gen_rtx_REG (reg_raw_mode[i], i),
4906 /* Mark the register as being dead. */
4908 /* The stack pointer is never dead. Well, not strictly true,
4909 but it's very difficult to tell from here. Hopefully
4910 combine_stack_adjustments will fix up the most egregious
4912 && regno_first != STACK_POINTER_REGNUM)
4914 for (i = regno_first; i <= regno_last; ++i)
4915 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
4916 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
4919 else if (GET_CODE (reg) == REG)
4921 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4922 pbi->reg_next_use[regno_first] = 0;
4925 /* If this is the last pass and this is a SCRATCH, show it will be dying
4926 here and count it. */
4927 else if (GET_CODE (reg) == SCRATCH)
4929 if (flags & PROP_DEATH_NOTES)
4931 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4935 #ifdef HAVE_conditional_execution
4936 /* Mark REGNO conditionally dead.
4937 Return true if the register is now unconditionally dead. */
4940 mark_regno_cond_dead (pbi, regno, cond)
4941 struct propagate_block_info *pbi;
4945 /* If this is a store to a predicate register, the value of the
4946 predicate is changing, we don't know that the predicate as seen
4947 before is the same as that seen after. Flush all dependent
4948 conditions from reg_cond_dead. This will make all such
4949 conditionally live registers unconditionally live. */
4950 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
4951 flush_reg_cond_reg (pbi, regno);
4953 /* If this is an unconditional store, remove any conditional
4954 life that may have existed. */
4955 if (cond == NULL_RTX)
4956 splay_tree_remove (pbi->reg_cond_dead, regno);
4959 splay_tree_node node;
4960 struct reg_cond_life_info *rcli;
4963 /* Otherwise this is a conditional set. Record that fact.
4964 It may have been conditionally used, or there may be a
4965 subsequent set with a complimentary condition. */
4967 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
4970 /* The register was unconditionally live previously.
4971 Record the current condition as the condition under
4972 which it is dead. */
4973 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4974 rcli->condition = cond;
4975 rcli->stores = cond;
4976 rcli->orig_condition = const0_rtx;
4977 splay_tree_insert (pbi->reg_cond_dead, regno,
4978 (splay_tree_value) rcli);
4980 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
4982 /* Not unconditionaly dead. */
4987 /* The register was conditionally live previously.
4988 Add the new condition to the old. */
4989 rcli = (struct reg_cond_life_info *) node->value;
4990 ncond = rcli->condition;
4991 ncond = ior_reg_cond (ncond, cond, 1);
4992 if (rcli->stores == const0_rtx)
4993 rcli->stores = cond;
4994 else if (rcli->stores != const1_rtx)
4995 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
4997 /* If the register is now unconditionally dead, remove the entry
4998 in the splay_tree. A register is unconditionally dead if the
4999 dead condition ncond is true. A register is also unconditionally
5000 dead if the sum of all conditional stores is an unconditional
5001 store (stores is true), and the dead condition is identically the
5002 same as the original dead condition initialized at the end of
5003 the block. This is a pointer compare, not an rtx_equal_p
5005 if (ncond == const1_rtx
5006 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
5007 splay_tree_remove (pbi->reg_cond_dead, regno);
5010 rcli->condition = ncond;
5012 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5014 /* Not unconditionaly dead. */
5023 /* Called from splay_tree_delete for pbi->reg_cond_life. */
5026 free_reg_cond_life_info (value)
5027 splay_tree_value value;
5029 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
5033 /* Helper function for flush_reg_cond_reg. */
5036 flush_reg_cond_reg_1 (node, data)
5037 splay_tree_node node;
5040 struct reg_cond_life_info *rcli;
5041 int *xdata = (int *) data;
5042 unsigned int regno = xdata[0];
5044 /* Don't need to search if last flushed value was farther on in
5045 the in-order traversal. */
5046 if (xdata[1] >= (int) node->key)
5049 /* Splice out portions of the expression that refer to regno. */
5050 rcli = (struct reg_cond_life_info *) node->value;
5051 rcli->condition = elim_reg_cond (rcli->condition, regno);
5052 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
5053 rcli->stores = elim_reg_cond (rcli->stores, regno);
5055 /* If the entire condition is now false, signal the node to be removed. */
5056 if (rcli->condition == const0_rtx)
5058 xdata[1] = node->key;
5061 else if (rcli->condition == const1_rtx)
5067 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
5070 flush_reg_cond_reg (pbi, regno)
5071 struct propagate_block_info *pbi;
5078 while (splay_tree_foreach (pbi->reg_cond_dead,
5079 flush_reg_cond_reg_1, pair) == -1)
5080 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
5082 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
5085 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
5086 For ior/and, the ADD flag determines whether we want to add the new
5087 condition X to the old one unconditionally. If it is zero, we will
5088 only return a new expression if X allows us to simplify part of
5089 OLD, otherwise we return OLD unchanged to the caller.
5090 If ADD is nonzero, we will return a new condition in all cases. The
5091 toplevel caller of one of these functions should always pass 1 for
5095 ior_reg_cond (old, x, add)
5101 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5103 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5104 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
5105 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5107 if (GET_CODE (x) == GET_CODE (old)
5108 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5112 return gen_rtx_IOR (0, old, x);
5115 switch (GET_CODE (old))
5118 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5119 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5120 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5122 if (op0 == const0_rtx)
5124 if (op1 == const0_rtx)
5126 if (op0 == const1_rtx || op1 == const1_rtx)
5128 if (op0 == XEXP (old, 0))
5129 op0 = gen_rtx_IOR (0, op0, x);
5131 op1 = gen_rtx_IOR (0, op1, x);
5132 return gen_rtx_IOR (0, op0, op1);
5136 return gen_rtx_IOR (0, old, x);
5139 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5140 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5141 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5143 if (op0 == const1_rtx)
5145 if (op1 == const1_rtx)
5147 if (op0 == const0_rtx || op1 == const0_rtx)
5149 if (op0 == XEXP (old, 0))
5150 op0 = gen_rtx_IOR (0, op0, x);
5152 op1 = gen_rtx_IOR (0, op1, x);
5153 return gen_rtx_AND (0, op0, op1);
5157 return gen_rtx_IOR (0, old, x);
5160 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5161 if (op0 != XEXP (old, 0))
5162 return not_reg_cond (op0);
5165 return gen_rtx_IOR (0, old, x);
5176 enum rtx_code x_code;
5178 if (x == const0_rtx)
5180 else if (x == const1_rtx)
5182 x_code = GET_CODE (x);
5185 if (GET_RTX_CLASS (x_code) == '<'
5186 && GET_CODE (XEXP (x, 0)) == REG)
5188 if (XEXP (x, 1) != const0_rtx)
5191 return gen_rtx_fmt_ee (reverse_condition (x_code),
5192 VOIDmode, XEXP (x, 0), const0_rtx);
5194 return gen_rtx_NOT (0, x);
5198 and_reg_cond (old, x, add)
5204 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5206 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5207 && GET_CODE (x) == reverse_condition (GET_CODE (old))
5208 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5210 if (GET_CODE (x) == GET_CODE (old)
5211 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5215 return gen_rtx_AND (0, old, x);
5218 switch (GET_CODE (old))
5221 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5222 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5223 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5225 if (op0 == const0_rtx)
5227 if (op1 == const0_rtx)
5229 if (op0 == const1_rtx || op1 == const1_rtx)
5231 if (op0 == XEXP (old, 0))
5232 op0 = gen_rtx_AND (0, op0, x);
5234 op1 = gen_rtx_AND (0, op1, x);
5235 return gen_rtx_IOR (0, op0, op1);
5239 return gen_rtx_AND (0, old, x);
5242 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5243 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5244 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5246 if (op0 == const1_rtx)
5248 if (op1 == const1_rtx)
5250 if (op0 == const0_rtx || op1 == const0_rtx)
5252 if (op0 == XEXP (old, 0))
5253 op0 = gen_rtx_AND (0, op0, x);
5255 op1 = gen_rtx_AND (0, op1, x);
5256 return gen_rtx_AND (0, op0, op1);
5261 /* If X is identical to one of the existing terms of the AND,
5262 then just return what we already have. */
5263 /* ??? There really should be some sort of recursive check here in
5264 case there are nested ANDs. */
5265 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
5266 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
5267 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
5268 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
5271 return gen_rtx_AND (0, old, x);
5274 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5275 if (op0 != XEXP (old, 0))
5276 return not_reg_cond (op0);
5279 return gen_rtx_AND (0, old, x);
5286 /* Given a condition X, remove references to reg REGNO and return the
5287 new condition. The removal will be done so that all conditions
5288 involving REGNO are considered to evaluate to false. This function
5289 is used when the value of REGNO changes. */
5292 elim_reg_cond (x, regno)
5298 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
5300 if (REGNO (XEXP (x, 0)) == regno)
5305 switch (GET_CODE (x))
5308 op0 = elim_reg_cond (XEXP (x, 0), regno);
5309 op1 = elim_reg_cond (XEXP (x, 1), regno);
5310 if (op0 == const0_rtx || op1 == const0_rtx)
5312 if (op0 == const1_rtx)
5314 if (op1 == const1_rtx)
5316 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5318 return gen_rtx_AND (0, op0, op1);
5321 op0 = elim_reg_cond (XEXP (x, 0), regno);
5322 op1 = elim_reg_cond (XEXP (x, 1), regno);
5323 if (op0 == const1_rtx || op1 == const1_rtx)
5325 if (op0 == const0_rtx)
5327 if (op1 == const0_rtx)
5329 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5331 return gen_rtx_IOR (0, op0, op1);
5334 op0 = elim_reg_cond (XEXP (x, 0), regno);
5335 if (op0 == const0_rtx)
5337 if (op0 == const1_rtx)
5339 if (op0 != XEXP (x, 0))
5340 return not_reg_cond (op0);
5347 #endif /* HAVE_conditional_execution */
5351 /* Try to substitute the auto-inc expression INC as the address inside
5352 MEM which occurs in INSN. Currently, the address of MEM is an expression
5353 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
5354 that has a single set whose source is a PLUS of INCR_REG and something
5358 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
5359 struct propagate_block_info *pbi;
5360 rtx inc, insn, mem, incr, incr_reg;
5362 int regno = REGNO (incr_reg);
5363 rtx set = single_set (incr);
5364 rtx q = SET_DEST (set);
5365 rtx y = SET_SRC (set);
5366 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
5368 /* Make sure this reg appears only once in this insn. */
5369 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
5372 if (dead_or_set_p (incr, incr_reg)
5373 /* Mustn't autoinc an eliminable register. */
5374 && (regno >= FIRST_PSEUDO_REGISTER
5375 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
5377 /* This is the simple case. Try to make the auto-inc. If
5378 we can't, we are done. Otherwise, we will do any
5379 needed updates below. */
5380 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
5383 else if (GET_CODE (q) == REG
5384 /* PREV_INSN used here to check the semi-open interval
5386 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5387 /* We must also check for sets of q as q may be
5388 a call clobbered hard register and there may
5389 be a call between PREV_INSN (insn) and incr. */
5390 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5392 /* We have *p followed sometime later by q = p+size.
5393 Both p and q must be live afterward,
5394 and q is not used between INSN and its assignment.
5395 Change it to q = p, ...*q..., q = q+size.
5396 Then fall into the usual case. */
5400 emit_move_insn (q, incr_reg);
5401 insns = get_insns ();
5404 if (basic_block_for_insn)
5405 for (temp = insns; temp; temp = NEXT_INSN (temp))
5406 set_block_for_insn (temp, pbi->bb);
5408 /* If we can't make the auto-inc, or can't make the
5409 replacement into Y, exit. There's no point in making
5410 the change below if we can't do the auto-inc and doing
5411 so is not correct in the pre-inc case. */
5414 validate_change (insn, &XEXP (mem, 0), inc, 1);
5415 validate_change (incr, &XEXP (y, opnum), q, 1);
5416 if (! apply_change_group ())
5419 /* We now know we'll be doing this change, so emit the
5420 new insn(s) and do the updates. */
5421 emit_insns_before (insns, insn);
5423 if (pbi->bb->head == insn)
5424 pbi->bb->head = insns;
5426 /* INCR will become a NOTE and INSN won't contain a
5427 use of INCR_REG. If a use of INCR_REG was just placed in
5428 the insn before INSN, make that the next use.
5429 Otherwise, invalidate it. */
5430 if (GET_CODE (PREV_INSN (insn)) == INSN
5431 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
5432 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
5433 pbi->reg_next_use[regno] = PREV_INSN (insn);
5435 pbi->reg_next_use[regno] = 0;
5440 /* REGNO is now used in INCR which is below INSN, but
5441 it previously wasn't live here. If we don't mark
5442 it as live, we'll put a REG_DEAD note for it
5443 on this insn, which is incorrect. */
5444 SET_REGNO_REG_SET (pbi->reg_live, regno);
5446 /* If there are any calls between INSN and INCR, show
5447 that REGNO now crosses them. */
5448 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
5449 if (GET_CODE (temp) == CALL_INSN)
5450 REG_N_CALLS_CROSSED (regno)++;
5455 /* If we haven't returned, it means we were able to make the
5456 auto-inc, so update the status. First, record that this insn
5457 has an implicit side effect. */
5459 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
5461 /* Modify the old increment-insn to simply copy
5462 the already-incremented value of our register. */
5463 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
5466 /* If that makes it a no-op (copying the register into itself) delete
5467 it so it won't appear to be a "use" and a "set" of this
5469 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
5471 /* If the original source was dead, it's dead now. */
5474 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
5476 remove_note (incr, note);
5477 if (XEXP (note, 0) != incr_reg)
5478 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
5481 PUT_CODE (incr, NOTE);
5482 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
5483 NOTE_SOURCE_FILE (incr) = 0;
5486 if (regno >= FIRST_PSEUDO_REGISTER)
5488 /* Count an extra reference to the reg. When a reg is
5489 incremented, spilling it is worse, so we want to make
5490 that less likely. */
5491 REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5493 /* Count the increment as a setting of the register,
5494 even though it isn't a SET in rtl. */
5495 REG_N_SETS (regno)++;
5499 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
5503 find_auto_inc (pbi, x, insn)
5504 struct propagate_block_info *pbi;
5508 rtx addr = XEXP (x, 0);
5509 HOST_WIDE_INT offset = 0;
5510 rtx set, y, incr, inc_val;
5512 int size = GET_MODE_SIZE (GET_MODE (x));
5514 if (GET_CODE (insn) == JUMP_INSN)
5517 /* Here we detect use of an index register which might be good for
5518 postincrement, postdecrement, preincrement, or predecrement. */
5520 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
5521 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
5523 if (GET_CODE (addr) != REG)
5526 regno = REGNO (addr);
5528 /* Is the next use an increment that might make auto-increment? */
5529 incr = pbi->reg_next_use[regno];
5530 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
5532 set = single_set (incr);
5533 if (set == 0 || GET_CODE (set) != SET)
5537 if (GET_CODE (y) != PLUS)
5540 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
5541 inc_val = XEXP (y, 1);
5542 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
5543 inc_val = XEXP (y, 0);
5547 if (GET_CODE (inc_val) == CONST_INT)
5549 if (HAVE_POST_INCREMENT
5550 && (INTVAL (inc_val) == size && offset == 0))
5551 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
5553 else if (HAVE_POST_DECREMENT
5554 && (INTVAL (inc_val) == -size && offset == 0))
5555 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
5557 else if (HAVE_PRE_INCREMENT
5558 && (INTVAL (inc_val) == size && offset == size))
5559 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
5561 else if (HAVE_PRE_DECREMENT
5562 && (INTVAL (inc_val) == -size && offset == -size))
5563 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
5565 else if (HAVE_POST_MODIFY_DISP && offset == 0)
5566 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5567 gen_rtx_PLUS (Pmode,
5570 insn, x, incr, addr);
5572 else if (GET_CODE (inc_val) == REG
5573 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
5577 if (HAVE_POST_MODIFY_REG && offset == 0)
5578 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5579 gen_rtx_PLUS (Pmode,
5582 insn, x, incr, addr);
5586 #endif /* AUTO_INC_DEC */
5589 mark_used_reg (pbi, reg, cond, insn)
5590 struct propagate_block_info *pbi;
5592 rtx cond ATTRIBUTE_UNUSED;
5595 unsigned int regno_first, regno_last, i;
5596 int some_was_live, some_was_dead, some_not_set;
5598 regno_last = regno_first = REGNO (reg);
5599 if (regno_first < FIRST_PSEUDO_REGISTER)
5600 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
5602 /* Find out if any of this register is live after this instruction. */
5603 some_was_live = some_was_dead = 0;
5604 for (i = regno_first; i <= regno_last; ++i)
5606 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
5607 some_was_live |= needed_regno;
5608 some_was_dead |= ! needed_regno;
5611 /* Find out if any of the register was set this insn. */
5613 for (i = regno_first; i <= regno_last; ++i)
5614 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
5616 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5618 /* Record where each reg is used, so when the reg is set we know
5619 the next insn that uses it. */
5620 pbi->reg_next_use[regno_first] = insn;
5623 if (pbi->flags & PROP_REG_INFO)
5625 if (regno_first < FIRST_PSEUDO_REGISTER)
5627 /* If this is a register we are going to try to eliminate,
5628 don't mark it live here. If we are successful in
5629 eliminating it, it need not be live unless it is used for
5630 pseudos, in which case it will have been set live when it
5631 was allocated to the pseudos. If the register will not
5632 be eliminated, reload will set it live at that point.
5634 Otherwise, record that this function uses this register. */
5635 /* ??? The PPC backend tries to "eliminate" on the pic
5636 register to itself. This should be fixed. In the mean
5637 time, hack around it. */
5639 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
5640 && (regno_first == FRAME_POINTER_REGNUM
5641 || regno_first == ARG_POINTER_REGNUM)))
5642 for (i = regno_first; i <= regno_last; ++i)
5643 regs_ever_live[i] = 1;
5647 /* Keep track of which basic block each reg appears in. */
5649 register int blocknum = pbi->bb->index;
5650 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
5651 REG_BASIC_BLOCK (regno_first) = blocknum;
5652 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
5653 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
5655 /* Count (weighted) number of uses of each reg. */
5656 REG_N_REFS (regno_first)
5657 += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5661 /* Record and count the insns in which a reg dies. If it is used in
5662 this insn and was dead below the insn then it dies in this insn.
5663 If it was set in this insn, we do not make a REG_DEAD note;
5664 likewise if we already made such a note. */
5665 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
5669 /* Check for the case where the register dying partially
5670 overlaps the register set by this insn. */
5671 if (regno_first != regno_last)
5672 for (i = regno_first; i <= regno_last; ++i)
5673 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
5675 /* If none of the words in X is needed, make a REG_DEAD note.
5676 Otherwise, we must make partial REG_DEAD notes. */
5677 if (! some_was_live)
5679 if ((pbi->flags & PROP_DEATH_NOTES)
5680 && ! find_regno_note (insn, REG_DEAD, regno_first))
5682 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
5684 if (pbi->flags & PROP_REG_INFO)
5685 REG_N_DEATHS (regno_first)++;
5689 /* Don't make a REG_DEAD note for a part of a register
5690 that is set in the insn. */
5691 for (i = regno_first; i <= regno_last; ++i)
5692 if (! REGNO_REG_SET_P (pbi->reg_live, i)
5693 && ! dead_or_set_regno_p (insn, i))
5695 = alloc_EXPR_LIST (REG_DEAD,
5696 gen_rtx_REG (reg_raw_mode[i], i),
5701 /* Mark the register as being live. */
5702 for (i = regno_first; i <= regno_last; ++i)
5704 SET_REGNO_REG_SET (pbi->reg_live, i);
5706 #ifdef HAVE_conditional_execution
5707 /* If this is a conditional use, record that fact. If it is later
5708 conditionally set, we'll know to kill the register. */
5709 if (cond != NULL_RTX)
5711 splay_tree_node node;
5712 struct reg_cond_life_info *rcli;
5717 node = splay_tree_lookup (pbi->reg_cond_dead, i);
5720 /* The register was unconditionally live previously.
5721 No need to do anything. */
5725 /* The register was conditionally live previously.
5726 Subtract the new life cond from the old death cond. */
5727 rcli = (struct reg_cond_life_info *) node->value;
5728 ncond = rcli->condition;
5729 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
5731 /* If the register is now unconditionally live,
5732 remove the entry in the splay_tree. */
5733 if (ncond == const0_rtx)
5734 splay_tree_remove (pbi->reg_cond_dead, i);
5737 rcli->condition = ncond;
5738 SET_REGNO_REG_SET (pbi->reg_cond_reg,
5739 REGNO (XEXP (cond, 0)));
5745 /* The register was not previously live at all. Record
5746 the condition under which it is still dead. */
5747 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5748 rcli->condition = not_reg_cond (cond);
5749 rcli->stores = const0_rtx;
5750 rcli->orig_condition = const0_rtx;
5751 splay_tree_insert (pbi->reg_cond_dead, i,
5752 (splay_tree_value) rcli);
5754 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5757 else if (some_was_live)
5759 /* The register may have been conditionally live previously, but
5760 is now unconditionally live. Remove it from the conditionally
5761 dead list, so that a conditional set won't cause us to think
5763 splay_tree_remove (pbi->reg_cond_dead, i);
5769 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5770 This is done assuming the registers needed from X are those that
5771 have 1-bits in PBI->REG_LIVE.
5773 INSN is the containing instruction. If INSN is dead, this function
5777 mark_used_regs (pbi, x, cond, insn)
5778 struct propagate_block_info *pbi;
5781 register RTX_CODE code;
5783 int flags = pbi->flags;
5786 code = GET_CODE (x);
5806 /* If we are clobbering a MEM, mark any registers inside the address
5808 if (GET_CODE (XEXP (x, 0)) == MEM)
5809 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
5813 /* Don't bother watching stores to mems if this is not the
5814 final pass. We'll not be deleting dead stores this round. */
5815 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5817 /* Invalidate the data for the last MEM stored, but only if MEM is
5818 something that can be stored into. */
5819 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
5820 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
5821 /* Needn't clear the memory set list. */
5825 rtx temp = pbi->mem_set_list;
5826 rtx prev = NULL_RTX;
5831 next = XEXP (temp, 1);
5832 if (anti_dependence (XEXP (temp, 0), x))
5834 /* Splice temp out of the list. */
5836 XEXP (prev, 1) = next;
5838 pbi->mem_set_list = next;
5839 free_EXPR_LIST_node (temp);
5840 pbi->mem_set_list_len--;
5848 /* If the memory reference had embedded side effects (autoincrement
5849 address modes. Then we may need to kill some entries on the
5852 invalidate_mems_from_autoinc (pbi, insn);
5856 if (flags & PROP_AUTOINC)
5857 find_auto_inc (pbi, x, insn);
5862 #ifdef CLASS_CANNOT_CHANGE_MODE
5863 if (GET_CODE (SUBREG_REG (x)) == REG
5864 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
5865 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
5866 GET_MODE (SUBREG_REG (x))))
5867 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
5870 /* While we're here, optimize this case. */
5872 if (GET_CODE (x) != REG)
5877 /* See a register other than being set => mark it as needed. */
5878 mark_used_reg (pbi, x, cond, insn);
5883 register rtx testreg = SET_DEST (x);
5886 /* If storing into MEM, don't show it as being used. But do
5887 show the address as being used. */
5888 if (GET_CODE (testreg) == MEM)
5891 if (flags & PROP_AUTOINC)
5892 find_auto_inc (pbi, testreg, insn);
5894 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
5895 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5899 /* Storing in STRICT_LOW_PART is like storing in a reg
5900 in that this SET might be dead, so ignore it in TESTREG.
5901 but in some other ways it is like using the reg.
5903 Storing in a SUBREG or a bit field is like storing the entire
5904 register in that if the register's value is not used
5905 then this SET is not needed. */
5906 while (GET_CODE (testreg) == STRICT_LOW_PART
5907 || GET_CODE (testreg) == ZERO_EXTRACT
5908 || GET_CODE (testreg) == SIGN_EXTRACT
5909 || GET_CODE (testreg) == SUBREG)
5911 #ifdef CLASS_CANNOT_CHANGE_MODE
5912 if (GET_CODE (testreg) == SUBREG
5913 && GET_CODE (SUBREG_REG (testreg)) == REG
5914 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
5915 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
5916 GET_MODE (testreg)))
5917 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
5920 /* Modifying a single register in an alternate mode
5921 does not use any of the old value. But these other
5922 ways of storing in a register do use the old value. */
5923 if (GET_CODE (testreg) == SUBREG
5924 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5929 testreg = XEXP (testreg, 0);
5932 /* If this is a store into a register or group of registers,
5933 recursively scan the value being stored. */
5935 if ((GET_CODE (testreg) == PARALLEL
5936 && GET_MODE (testreg) == BLKmode)
5937 || (GET_CODE (testreg) == REG
5938 && (regno = REGNO (testreg),
5939 ! (regno == FRAME_POINTER_REGNUM
5940 && (! reload_completed || frame_pointer_needed)))
5941 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5942 && ! (regno == HARD_FRAME_POINTER_REGNUM
5943 && (! reload_completed || frame_pointer_needed))
5945 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5946 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5951 mark_used_regs (pbi, SET_DEST (x), cond, insn);
5952 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5959 case UNSPEC_VOLATILE:
5963 /* Traditional and volatile asm instructions must be considered to use
5964 and clobber all hard registers, all pseudo-registers and all of
5965 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
5967 Consider for instance a volatile asm that changes the fpu rounding
5968 mode. An insn should not be moved across this even if it only uses
5969 pseudo-regs because it might give an incorrectly rounded result.
5971 ?!? Unfortunately, marking all hard registers as live causes massive
5972 problems for the register allocator and marking all pseudos as live
5973 creates mountains of uninitialized variable warnings.
5975 So for now, just clear the memory set list and mark any regs
5976 we can find in ASM_OPERANDS as used. */
5977 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
5979 free_EXPR_LIST_list (&pbi->mem_set_list);
5980 pbi->mem_set_list_len = 0;
5983 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
5984 We can not just fall through here since then we would be confused
5985 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
5986 traditional asms unlike their normal usage. */
5987 if (code == ASM_OPERANDS)
5991 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
5992 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
5998 if (cond != NULL_RTX)
6001 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
6003 cond = COND_EXEC_TEST (x);
6004 x = COND_EXEC_CODE (x);
6008 /* We _do_not_ want to scan operands of phi nodes. Operands of
6009 a phi function are evaluated only when control reaches this
6010 block along a particular edge. Therefore, regs that appear
6011 as arguments to phi should not be added to the global live at
6019 /* Recursively scan the operands of this expression. */
6022 register const char *fmt = GET_RTX_FORMAT (code);
6025 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6029 /* Tail recursive case: save a function call level. */
6035 mark_used_regs (pbi, XEXP (x, i), cond, insn);
6037 else if (fmt[i] == 'E')
6040 for (j = 0; j < XVECLEN (x, i); j++)
6041 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
6050 try_pre_increment_1 (pbi, insn)
6051 struct propagate_block_info *pbi;
6054 /* Find the next use of this reg. If in same basic block,
6055 make it do pre-increment or pre-decrement if appropriate. */
6056 rtx x = single_set (insn);
6057 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
6058 * INTVAL (XEXP (SET_SRC (x), 1)));
6059 int regno = REGNO (SET_DEST (x));
6060 rtx y = pbi->reg_next_use[regno];
6062 && SET_DEST (x) != stack_pointer_rtx
6063 && BLOCK_NUM (y) == BLOCK_NUM (insn)
6064 /* Don't do this if the reg dies, or gets set in y; a standard addressing
6065 mode would be better. */
6066 && ! dead_or_set_p (y, SET_DEST (x))
6067 && try_pre_increment (y, SET_DEST (x), amount))
6069 /* We have found a suitable auto-increment and already changed
6070 insn Y to do it. So flush this increment instruction. */
6071 propagate_block_delete_insn (pbi->bb, insn);
6073 /* Count a reference to this reg for the increment insn we are
6074 deleting. When a reg is incremented, spilling it is worse,
6075 so we want to make that less likely. */
6076 if (regno >= FIRST_PSEUDO_REGISTER)
6078 REG_N_REFS (regno) += (optimize_size ? 1
6079 : pbi->bb->loop_depth + 1);
6080 REG_N_SETS (regno)++;
6083 /* Flush any remembered memories depending on the value of
6084 the incremented register. */
6085 invalidate_mems_from_set (pbi, SET_DEST (x));
6092 /* Try to change INSN so that it does pre-increment or pre-decrement
6093 addressing on register REG in order to add AMOUNT to REG.
6094 AMOUNT is negative for pre-decrement.
6095 Returns 1 if the change could be made.
6096 This checks all about the validity of the result of modifying INSN. */
6099 try_pre_increment (insn, reg, amount)
6101 HOST_WIDE_INT amount;
6105 /* Nonzero if we can try to make a pre-increment or pre-decrement.
6106 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
6108 /* Nonzero if we can try to make a post-increment or post-decrement.
6109 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
6110 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
6111 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
6114 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
6117 /* From the sign of increment, see which possibilities are conceivable
6118 on this target machine. */
6119 if (HAVE_PRE_INCREMENT && amount > 0)
6121 if (HAVE_POST_INCREMENT && amount > 0)
6124 if (HAVE_PRE_DECREMENT && amount < 0)
6126 if (HAVE_POST_DECREMENT && amount < 0)
6129 if (! (pre_ok || post_ok))
6132 /* It is not safe to add a side effect to a jump insn
6133 because if the incremented register is spilled and must be reloaded
6134 there would be no way to store the incremented value back in memory. */
6136 if (GET_CODE (insn) == JUMP_INSN)
6141 use = find_use_as_address (PATTERN (insn), reg, 0);
6142 if (post_ok && (use == 0 || use == (rtx) 1))
6144 use = find_use_as_address (PATTERN (insn), reg, -amount);
6148 if (use == 0 || use == (rtx) 1)
6151 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
6154 /* See if this combination of instruction and addressing mode exists. */
6155 if (! validate_change (insn, &XEXP (use, 0),
6156 gen_rtx_fmt_e (amount > 0
6157 ? (do_post ? POST_INC : PRE_INC)
6158 : (do_post ? POST_DEC : PRE_DEC),
6162 /* Record that this insn now has an implicit side effect on X. */
6163 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
6167 #endif /* AUTO_INC_DEC */
6169 /* Find the place in the rtx X where REG is used as a memory address.
6170 Return the MEM rtx that so uses it.
6171 If PLUSCONST is nonzero, search instead for a memory address equivalent to
6172 (plus REG (const_int PLUSCONST)).
6174 If such an address does not appear, return 0.
6175 If REG appears more than once, or is used other than in such an address,
6179 find_use_as_address (x, reg, plusconst)
6182 HOST_WIDE_INT plusconst;
6184 enum rtx_code code = GET_CODE (x);
6185 const char *fmt = GET_RTX_FORMAT (code);
6187 register rtx value = 0;
6190 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
6193 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
6194 && XEXP (XEXP (x, 0), 0) == reg
6195 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6196 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
6199 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
6201 /* If REG occurs inside a MEM used in a bit-field reference,
6202 that is unacceptable. */
6203 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
6204 return (rtx) (HOST_WIDE_INT) 1;
6208 return (rtx) (HOST_WIDE_INT) 1;
6210 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6214 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
6218 return (rtx) (HOST_WIDE_INT) 1;
6220 else if (fmt[i] == 'E')
6223 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6225 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
6229 return (rtx) (HOST_WIDE_INT) 1;
6237 /* Write information about registers and basic blocks into FILE.
6238 This is part of making a debugging dump. */
6241 dump_regset (r, outf)
6248 fputs (" (nil)", outf);
6252 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
6254 fprintf (outf, " %d", i);
6255 if (i < FIRST_PSEUDO_REGISTER)
6256 fprintf (outf, " [%s]",
6265 dump_regset (r, stderr);
6266 putc ('\n', stderr);
6270 dump_flow_info (file)
6274 static const char * const reg_class_names[] = REG_CLASS_NAMES;
6276 fprintf (file, "%d registers.\n", max_regno);
6277 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
6280 enum reg_class class, altclass;
6281 fprintf (file, "\nRegister %d used %d times across %d insns",
6282 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
6283 if (REG_BASIC_BLOCK (i) >= 0)
6284 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
6286 fprintf (file, "; set %d time%s", REG_N_SETS (i),
6287 (REG_N_SETS (i) == 1) ? "" : "s");
6288 if (REG_USERVAR_P (regno_reg_rtx[i]))
6289 fprintf (file, "; user var");
6290 if (REG_N_DEATHS (i) != 1)
6291 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
6292 if (REG_N_CALLS_CROSSED (i) == 1)
6293 fprintf (file, "; crosses 1 call");
6294 else if (REG_N_CALLS_CROSSED (i))
6295 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
6296 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
6297 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
6298 class = reg_preferred_class (i);
6299 altclass = reg_alternate_class (i);
6300 if (class != GENERAL_REGS || altclass != ALL_REGS)
6302 if (altclass == ALL_REGS || class == ALL_REGS)
6303 fprintf (file, "; pref %s", reg_class_names[(int) class]);
6304 else if (altclass == NO_REGS)
6305 fprintf (file, "; %s or none", reg_class_names[(int) class]);
6307 fprintf (file, "; pref %s, else %s",
6308 reg_class_names[(int) class],
6309 reg_class_names[(int) altclass]);
6311 if (REG_POINTER (regno_reg_rtx[i]))
6312 fprintf (file, "; pointer");
6313 fprintf (file, ".\n");
6316 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
6317 for (i = 0; i < n_basic_blocks; i++)
6319 register basic_block bb = BASIC_BLOCK (i);
6322 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
6323 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count);
6325 fprintf (file, "Predecessors: ");
6326 for (e = bb->pred; e; e = e->pred_next)
6327 dump_edge_info (file, e, 0);
6329 fprintf (file, "\nSuccessors: ");
6330 for (e = bb->succ; e; e = e->succ_next)
6331 dump_edge_info (file, e, 1);
6333 fprintf (file, "\nRegisters live at start:");
6334 dump_regset (bb->global_live_at_start, file);
6336 fprintf (file, "\nRegisters live at end:");
6337 dump_regset (bb->global_live_at_end, file);
6348 dump_flow_info (stderr);
6352 dump_edge_info (file, e, do_succ)
6357 basic_block side = (do_succ ? e->dest : e->src);
6359 if (side == ENTRY_BLOCK_PTR)
6360 fputs (" ENTRY", file);
6361 else if (side == EXIT_BLOCK_PTR)
6362 fputs (" EXIT", file);
6364 fprintf (file, " %d", side->index);
6367 fprintf (file, " count:%d", e->count);
6371 static const char * const bitnames[] = {
6372 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6375 int i, flags = e->flags;
6379 for (i = 0; flags; i++)
6380 if (flags & (1 << i))
6386 if (i < (int) ARRAY_SIZE (bitnames))
6387 fputs (bitnames[i], file);
6389 fprintf (file, "%d", i);
6396 /* Print out one basic block with live information at start and end. */
6407 fprintf (outf, ";; Basic block %d, loop depth %d, count %d",
6408 bb->index, bb->loop_depth, bb->count);
6411 fputs (";; Predecessors: ", outf);
6412 for (e = bb->pred; e; e = e->pred_next)
6413 dump_edge_info (outf, e, 0);
6416 fputs (";; Registers live at start:", outf);
6417 dump_regset (bb->global_live_at_start, outf);
6420 for (insn = bb->head, last = NEXT_INSN (bb->end);
6422 insn = NEXT_INSN (insn))
6423 print_rtl_single (outf, insn);
6425 fputs (";; Registers live at end:", outf);
6426 dump_regset (bb->global_live_at_end, outf);
6429 fputs (";; Successors: ", outf);
6430 for (e = bb->succ; e; e = e->succ_next)
6431 dump_edge_info (outf, e, 1);
6439 dump_bb (bb, stderr);
6446 dump_bb (BASIC_BLOCK (n), stderr);
6449 /* Like print_rtl, but also print out live information for the start of each
6453 print_rtl_with_bb (outf, rtx_first)
6457 register rtx tmp_rtx;
6460 fprintf (outf, "(nil)\n");
6464 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
6465 int max_uid = get_max_uid ();
6466 basic_block *start = (basic_block *)
6467 xcalloc (max_uid, sizeof (basic_block));
6468 basic_block *end = (basic_block *)
6469 xcalloc (max_uid, sizeof (basic_block));
6470 enum bb_state *in_bb_p = (enum bb_state *)
6471 xcalloc (max_uid, sizeof (enum bb_state));
6473 for (i = n_basic_blocks - 1; i >= 0; i--)
6475 basic_block bb = BASIC_BLOCK (i);
6478 start[INSN_UID (bb->head)] = bb;
6479 end[INSN_UID (bb->end)] = bb;
6480 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
6482 enum bb_state state = IN_MULTIPLE_BB;
6483 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
6485 in_bb_p[INSN_UID (x)] = state;
6492 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
6497 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
6499 fprintf (outf, ";; Start of basic block %d, registers live:",
6501 dump_regset (bb->global_live_at_start, outf);
6505 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
6506 && GET_CODE (tmp_rtx) != NOTE
6507 && GET_CODE (tmp_rtx) != BARRIER)
6508 fprintf (outf, ";; Insn is not within a basic block\n");
6509 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
6510 fprintf (outf, ";; Insn is in multiple basic blocks\n");
6512 did_output = print_rtl_single (outf, tmp_rtx);
6514 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
6516 fprintf (outf, ";; End of basic block %d, registers live:\n",
6518 dump_regset (bb->global_live_at_end, outf);
6531 if (current_function_epilogue_delay_list != 0)
6533 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
6534 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
6535 tmp_rtx = XEXP (tmp_rtx, 1))
6536 print_rtl_single (outf, XEXP (tmp_rtx, 0));
6540 /* Dump the rtl into the current debugging dump file, then abort. */
6543 print_rtl_and_abort_fcn (file, line, function)
6546 const char *function;
6550 print_rtl_with_bb (rtl_dump_file, get_insns ());
6551 fclose (rtl_dump_file);
6554 fancy_abort (file, line, function);
6557 /* Recompute register set/reference counts immediately prior to register
6560 This avoids problems with set/reference counts changing to/from values
6561 which have special meanings to the register allocators.
6563 Additionally, the reference counts are the primary component used by the
6564 register allocators to prioritize pseudos for allocation to hard regs.
6565 More accurate reference counts generally lead to better register allocation.
6567 F is the first insn to be scanned.
6569 LOOP_STEP denotes how much loop_depth should be incremented per
6570 loop nesting level in order to increase the ref count more for
6571 references in a loop.
6573 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6574 possibly other information which is used by the register allocators. */
6577 recompute_reg_usage (f, loop_step)
6578 rtx f ATTRIBUTE_UNUSED;
6579 int loop_step ATTRIBUTE_UNUSED;
6581 allocate_reg_life_data ();
6582 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
6585 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6586 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6587 of the number of registers that died. */
6590 count_or_remove_death_notes (blocks, kill)
6596 for (i = n_basic_blocks - 1; i >= 0; --i)
6601 if (blocks && ! TEST_BIT (blocks, i))
6604 bb = BASIC_BLOCK (i);
6606 for (insn = bb->head;; insn = NEXT_INSN (insn))
6610 rtx *pprev = ®_NOTES (insn);
6615 switch (REG_NOTE_KIND (link))
6618 if (GET_CODE (XEXP (link, 0)) == REG)
6620 rtx reg = XEXP (link, 0);
6623 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
6626 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
6634 rtx next = XEXP (link, 1);
6635 free_EXPR_LIST_node (link);
6636 *pprev = link = next;
6642 pprev = &XEXP (link, 1);
6649 if (insn == bb->end)
6658 /* Update insns block within BB. */
6661 update_bb_for_insn (bb)
6666 if (! basic_block_for_insn)
6669 for (insn = bb->head; ; insn = NEXT_INSN (insn))
6671 set_block_for_insn (insn, bb);
6673 if (insn == bb->end)
6679 /* Record INSN's block as BB. */
6682 set_block_for_insn (insn, bb)
6686 size_t uid = INSN_UID (insn);
6687 if (uid >= basic_block_for_insn->num_elements)
6691 /* Add one-eighth the size so we don't keep calling xrealloc. */
6692 new_size = uid + (uid + 7) / 8;
6694 VARRAY_GROW (basic_block_for_insn, new_size);
6696 VARRAY_BB (basic_block_for_insn, uid) = bb;
6699 /* When a new insn has been inserted into an existing block, it will
6700 sometimes emit more than a single insn. This routine will set the
6701 block number for the specified insn, and look backwards in the insn
6702 chain to see if there are any other uninitialized insns immediately
6703 previous to this one, and set the block number for them too. */
6706 set_block_for_new_insns (insn, bb)
6710 set_block_for_insn (insn, bb);
6712 /* Scan the previous instructions setting the block number until we find
6713 an instruction that has the block number set, or we find a note
6715 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
6717 if (GET_CODE (insn) == NOTE)
6719 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
6720 || BLOCK_FOR_INSN (insn) == 0)
6721 set_block_for_insn (insn, bb);
6727 /* Verify the CFG consistency. This function check some CFG invariants and
6728 aborts when something is wrong. Hope that this function will help to
6729 convert many optimization passes to preserve CFG consistent.
6731 Currently it does following checks:
6733 - test head/end pointers
6734 - overlapping of basic blocks
6735 - edge list corectness
6736 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6737 - tails of basic blocks (ensure that boundary is necesary)
6738 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6739 and NOTE_INSN_BASIC_BLOCK
6740 - check that all insns are in the basic blocks
6741 (except the switch handling code, barriers and notes)
6742 - check that all returns are followed by barriers
6744 In future it can be extended check a lot of other stuff as well
6745 (reachability of basic blocks, life information, etc. etc.). */
6750 const int max_uid = get_max_uid ();
6751 const rtx rtx_first = get_insns ();
6752 rtx last_head = get_last_insn ();
6753 basic_block *bb_info;
6755 int i, last_bb_num_seen, num_bb_notes, err = 0;
6757 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
6759 for (i = n_basic_blocks - 1; i >= 0; i--)
6761 basic_block bb = BASIC_BLOCK (i);
6762 rtx head = bb->head;
6765 /* Verify the end of the basic block is in the INSN chain. */
6766 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
6771 error ("End insn %d for block %d not found in the insn stream.",
6772 INSN_UID (end), bb->index);
6776 /* Work backwards from the end to the head of the basic block
6777 to verify the head is in the RTL chain. */
6778 for (; x != NULL_RTX; x = PREV_INSN (x))
6780 /* While walking over the insn chain, verify insns appear
6781 in only one basic block and initialize the BB_INFO array
6782 used by other passes. */
6783 if (bb_info[INSN_UID (x)] != NULL)
6785 error ("Insn %d is in multiple basic blocks (%d and %d)",
6786 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
6789 bb_info[INSN_UID (x)] = bb;
6796 error ("Head insn %d for block %d not found in the insn stream.",
6797 INSN_UID (head), bb->index);
6804 /* Now check the basic blocks (boundaries etc.) */
6805 for (i = n_basic_blocks - 1; i >= 0; i--)
6807 basic_block bb = BASIC_BLOCK (i);
6808 /* Check corectness of edge lists */
6817 "verify_flow_info: Basic block %d succ edge is corrupted\n",
6819 fprintf (stderr, "Predecessor: ");
6820 dump_edge_info (stderr, e, 0);
6821 fprintf (stderr, "\nSuccessor: ");
6822 dump_edge_info (stderr, e, 1);
6826 if (e->dest != EXIT_BLOCK_PTR)
6828 edge e2 = e->dest->pred;
6829 while (e2 && e2 != e)
6833 error ("Basic block %i edge lists are corrupted", bb->index);
6845 error ("Basic block %d pred edge is corrupted", bb->index);
6846 fputs ("Predecessor: ", stderr);
6847 dump_edge_info (stderr, e, 0);
6848 fputs ("\nSuccessor: ", stderr);
6849 dump_edge_info (stderr, e, 1);
6850 fputc ('\n', stderr);
6853 if (e->src != ENTRY_BLOCK_PTR)
6855 edge e2 = e->src->succ;
6856 while (e2 && e2 != e)
6860 error ("Basic block %i edge lists are corrupted", bb->index);
6867 /* OK pointers are correct. Now check the header of basic
6868 block. It ought to contain optional CODE_LABEL followed
6869 by NOTE_BASIC_BLOCK. */
6871 if (GET_CODE (x) == CODE_LABEL)
6875 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6881 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
6883 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6890 /* Do checks for empty blocks here */
6897 if (NOTE_INSN_BASIC_BLOCK_P (x))
6899 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6900 INSN_UID (x), bb->index);
6907 if (GET_CODE (x) == JUMP_INSN
6908 || GET_CODE (x) == CODE_LABEL
6909 || GET_CODE (x) == BARRIER)
6911 error ("In basic block %d:", bb->index);
6912 fatal_insn ("Flow control insn inside a basic block", x);
6920 last_bb_num_seen = -1;
6925 if (NOTE_INSN_BASIC_BLOCK_P (x))
6927 basic_block bb = NOTE_BASIC_BLOCK (x);
6929 if (bb->index != last_bb_num_seen + 1)
6930 /* Basic blocks not numbered consecutively. */
6933 last_bb_num_seen = bb->index;
6936 if (!bb_info[INSN_UID (x)])
6938 switch (GET_CODE (x))
6945 /* An addr_vec is placed outside any block block. */
6947 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
6948 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
6949 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
6954 /* But in any case, non-deletable labels can appear anywhere. */
6958 fatal_insn ("Insn outside basic block", x);
6963 && GET_CODE (x) == JUMP_INSN
6964 && returnjump_p (x) && ! condjump_p (x)
6965 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
6966 fatal_insn ("Return not followed by barrier", x);
6971 if (num_bb_notes != n_basic_blocks)
6973 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
6974 num_bb_notes, n_basic_blocks);
6983 /* Functions to access an edge list with a vector representation.
6984 Enough data is kept such that given an index number, the
6985 pred and succ that edge represents can be determined, or
6986 given a pred and a succ, its index number can be returned.
6987 This allows algorithms which consume a lot of memory to
6988 represent the normally full matrix of edge (pred,succ) with a
6989 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
6990 wasted space in the client code due to sparse flow graphs. */
6992 /* This functions initializes the edge list. Basically the entire
6993 flowgraph is processed, and all edges are assigned a number,
6994 and the data structure is filled in. */
6999 struct edge_list *elist;
7005 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
7009 /* Determine the number of edges in the flow graph by counting successor
7010 edges on each basic block. */
7011 for (x = 0; x < n_basic_blocks; x++)
7013 basic_block bb = BASIC_BLOCK (x);
7015 for (e = bb->succ; e; e = e->succ_next)
7018 /* Don't forget successors of the entry block. */
7019 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7022 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
7023 elist->num_blocks = block_count;
7024 elist->num_edges = num_edges;
7025 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
7029 /* Follow successors of the entry block, and register these edges. */
7030 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7032 elist->index_to_edge[num_edges] = e;
7036 for (x = 0; x < n_basic_blocks; x++)
7038 basic_block bb = BASIC_BLOCK (x);
7040 /* Follow all successors of blocks, and register these edges. */
7041 for (e = bb->succ; e; e = e->succ_next)
7043 elist->index_to_edge[num_edges] = e;
7050 /* This function free's memory associated with an edge list. */
7053 free_edge_list (elist)
7054 struct edge_list *elist;
7058 free (elist->index_to_edge);
7063 /* This function provides debug output showing an edge list. */
7066 print_edge_list (f, elist)
7068 struct edge_list *elist;
7071 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
7072 elist->num_blocks - 2, elist->num_edges);
7074 for (x = 0; x < elist->num_edges; x++)
7076 fprintf (f, " %-4d - edge(", x);
7077 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
7078 fprintf (f, "entry,");
7080 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
7082 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
7083 fprintf (f, "exit)\n");
7085 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
7089 /* This function provides an internal consistency check of an edge list,
7090 verifying that all edges are present, and that there are no
7094 verify_edge_list (f, elist)
7096 struct edge_list *elist;
7098 int x, pred, succ, index;
7101 for (x = 0; x < n_basic_blocks; x++)
7103 basic_block bb = BASIC_BLOCK (x);
7105 for (e = bb->succ; e; e = e->succ_next)
7107 pred = e->src->index;
7108 succ = e->dest->index;
7109 index = EDGE_INDEX (elist, e->src, e->dest);
7110 if (index == EDGE_INDEX_NO_EDGE)
7112 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7115 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7116 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7117 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7118 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7119 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7120 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7123 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7125 pred = e->src->index;
7126 succ = e->dest->index;
7127 index = EDGE_INDEX (elist, e->src, e->dest);
7128 if (index == EDGE_INDEX_NO_EDGE)
7130 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7133 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7134 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7135 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7136 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7137 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7138 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7140 /* We've verified that all the edges are in the list, no lets make sure
7141 there are no spurious edges in the list. */
7143 for (pred = 0; pred < n_basic_blocks; pred++)
7144 for (succ = 0; succ < n_basic_blocks; succ++)
7146 basic_block p = BASIC_BLOCK (pred);
7147 basic_block s = BASIC_BLOCK (succ);
7151 for (e = p->succ; e; e = e->succ_next)
7157 for (e = s->pred; e; e = e->pred_next)
7163 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7164 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7165 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
7167 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7168 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7169 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
7170 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7171 BASIC_BLOCK (succ)));
7173 for (succ = 0; succ < n_basic_blocks; succ++)
7175 basic_block p = ENTRY_BLOCK_PTR;
7176 basic_block s = BASIC_BLOCK (succ);
7180 for (e = p->succ; e; e = e->succ_next)
7186 for (e = s->pred; e; e = e->pred_next)
7192 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7193 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7194 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
7196 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7197 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7198 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
7199 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
7200 BASIC_BLOCK (succ)));
7202 for (pred = 0; pred < n_basic_blocks; pred++)
7204 basic_block p = BASIC_BLOCK (pred);
7205 basic_block s = EXIT_BLOCK_PTR;
7209 for (e = p->succ; e; e = e->succ_next)
7215 for (e = s->pred; e; e = e->pred_next)
7221 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7222 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7223 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
7225 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7226 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7227 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7228 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7233 /* This routine will determine what, if any, edge there is between
7234 a specified predecessor and successor. */
7237 find_edge_index (edge_list, pred, succ)
7238 struct edge_list *edge_list;
7239 basic_block pred, succ;
7242 for (x = 0; x < NUM_EDGES (edge_list); x++)
7244 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7245 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7248 return (EDGE_INDEX_NO_EDGE);
7251 /* This function will remove an edge from the flow graph. */
7257 edge last_pred = NULL;
7258 edge last_succ = NULL;
7260 basic_block src, dest;
7263 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7269 last_succ->succ_next = e->succ_next;
7271 src->succ = e->succ_next;
7273 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7279 last_pred->pred_next = e->pred_next;
7281 dest->pred = e->pred_next;
7287 /* This routine will remove any fake successor edges for a basic block.
7288 When the edge is removed, it is also removed from whatever predecessor
7292 remove_fake_successors (bb)
7296 for (e = bb->succ; e;)
7300 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7305 /* This routine will remove all fake edges from the flow graph. If
7306 we remove all fake successors, it will automatically remove all
7307 fake predecessors. */
7310 remove_fake_edges ()
7314 for (x = 0; x < n_basic_blocks; x++)
7315 remove_fake_successors (BASIC_BLOCK (x));
7317 /* We've handled all successors except the entry block's. */
7318 remove_fake_successors (ENTRY_BLOCK_PTR);
7321 /* This function will add a fake edge between any block which has no
7322 successors, and the exit block. Some data flow equations require these
7326 add_noreturn_fake_exit_edges ()
7330 for (x = 0; x < n_basic_blocks; x++)
7331 if (BASIC_BLOCK (x)->succ == NULL)
7332 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7335 /* This function adds a fake edge between any infinite loops to the
7336 exit block. Some optimizations require a path from each node to
7339 See also Morgan, Figure 3.10, pp. 82-83.
7341 The current implementation is ugly, not attempting to minimize the
7342 number of inserted fake edges. To reduce the number of fake edges
7343 to insert, add fake edges from _innermost_ loops containing only
7344 nodes not reachable from the exit block. */
7347 connect_infinite_loops_to_exit ()
7349 basic_block unvisited_block;
7351 /* Perform depth-first search in the reverse graph to find nodes
7352 reachable from the exit block. */
7353 struct depth_first_search_dsS dfs_ds;
7355 flow_dfs_compute_reverse_init (&dfs_ds);
7356 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7358 /* Repeatedly add fake edges, updating the unreachable nodes. */
7361 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7362 if (!unvisited_block)
7364 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7365 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7368 flow_dfs_compute_reverse_finish (&dfs_ds);
7373 /* Redirect an edge's successor from one block to another. */
7376 redirect_edge_succ (e, new_succ)
7378 basic_block new_succ;
7382 /* Disconnect the edge from the old successor block. */
7383 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7385 *pe = (*pe)->pred_next;
7387 /* Reconnect the edge to the new successor block. */
7388 e->pred_next = new_succ->pred;
7393 /* Redirect an edge's predecessor from one block to another. */
7396 redirect_edge_pred (e, new_pred)
7398 basic_block new_pred;
7402 /* Disconnect the edge from the old predecessor block. */
7403 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7405 *pe = (*pe)->succ_next;
7407 /* Reconnect the edge to the new predecessor block. */
7408 e->succ_next = new_pred->succ;
7413 /* Dump the list of basic blocks in the bitmap NODES. */
7416 flow_nodes_print (str, nodes, file)
7418 const sbitmap nodes;
7426 fprintf (file, "%s { ", str);
7427 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
7428 fputs ("}\n", file);
7432 /* Dump the list of edges in the array EDGE_LIST. */
7435 flow_edge_list_print (str, edge_list, num_edges, file)
7437 const edge *edge_list;
7446 fprintf (file, "%s { ", str);
7447 for (i = 0; i < num_edges; i++)
7448 fprintf (file, "%d->%d ", edge_list[i]->src->index,
7449 edge_list[i]->dest->index);
7450 fputs ("}\n", file);
7454 /* Dump loop related CFG information. */
7457 flow_loops_cfg_dump (loops, file)
7458 const struct loops *loops;
7463 if (! loops->num || ! file || ! loops->cfg.dom)
7466 for (i = 0; i < n_basic_blocks; i++)
7470 fprintf (file, ";; %d succs { ", i);
7471 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
7472 fprintf (file, "%d ", succ->dest->index);
7473 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
7476 /* Dump the DFS node order. */
7477 if (loops->cfg.dfs_order)
7479 fputs (";; DFS order: ", file);
7480 for (i = 0; i < n_basic_blocks; i++)
7481 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
7484 /* Dump the reverse completion node order. */
7485 if (loops->cfg.rc_order)
7487 fputs (";; RC order: ", file);
7488 for (i = 0; i < n_basic_blocks; i++)
7489 fprintf (file, "%d ", loops->cfg.rc_order[i]);
7494 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7497 flow_loop_nested_p (outer, loop)
7501 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
7505 /* Dump the loop information specified by LOOP to the stream FILE
7506 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7508 flow_loop_dump (loop, file, loop_dump_aux, verbose)
7509 const struct loop *loop;
7511 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7514 if (! loop || ! loop->header)
7517 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
7518 loop->num, INSN_UID (loop->first->head),
7519 INSN_UID (loop->last->end),
7520 loop->shared ? " shared" : "",
7521 loop->invalid ? " invalid" : "");
7522 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
7523 loop->header->index, loop->latch->index,
7524 loop->pre_header ? loop->pre_header->index : -1,
7525 loop->first->index, loop->last->index);
7526 fprintf (file, ";; depth %d, level %d, outer %ld\n",
7527 loop->depth, loop->level,
7528 (long) (loop->outer ? loop->outer->num : -1));
7530 if (loop->pre_header_edges)
7531 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
7532 loop->num_pre_header_edges, file);
7533 flow_edge_list_print (";; entry edges", loop->entry_edges,
7534 loop->num_entries, file);
7535 fprintf (file, ";; %d", loop->num_nodes);
7536 flow_nodes_print (" nodes", loop->nodes, file);
7537 flow_edge_list_print (";; exit edges", loop->exit_edges,
7538 loop->num_exits, file);
7539 if (loop->exits_doms)
7540 flow_nodes_print (";; exit doms", loop->exits_doms, file);
7542 loop_dump_aux (loop, file, verbose);
7546 /* Dump the loop information specified by LOOPS to the stream FILE,
7547 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7549 flow_loops_dump (loops, file, loop_dump_aux, verbose)
7550 const struct loops *loops;
7552 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7558 num_loops = loops->num;
7559 if (! num_loops || ! file)
7562 fprintf (file, ";; %d loops found, %d levels\n",
7563 num_loops, loops->levels);
7565 for (i = 0; i < num_loops; i++)
7567 struct loop *loop = &loops->array[i];
7569 flow_loop_dump (loop, file, loop_dump_aux, verbose);
7575 for (j = 0; j < i; j++)
7577 struct loop *oloop = &loops->array[j];
7579 if (loop->header == oloop->header)
7584 smaller = loop->num_nodes < oloop->num_nodes;
7586 /* If the union of LOOP and OLOOP is different than
7587 the larger of LOOP and OLOOP then LOOP and OLOOP
7588 must be disjoint. */
7589 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
7590 smaller ? oloop : loop);
7592 ";; loop header %d shared by loops %d, %d %s\n",
7593 loop->header->index, i, j,
7594 disjoint ? "disjoint" : "nested");
7601 flow_loops_cfg_dump (loops, file);
7605 /* Free all the memory allocated for LOOPS. */
7608 flow_loops_free (loops)
7609 struct loops *loops;
7618 /* Free the loop descriptors. */
7619 for (i = 0; i < loops->num; i++)
7621 struct loop *loop = &loops->array[i];
7623 if (loop->pre_header_edges)
7624 free (loop->pre_header_edges);
7626 sbitmap_free (loop->nodes);
7627 if (loop->entry_edges)
7628 free (loop->entry_edges);
7629 if (loop->exit_edges)
7630 free (loop->exit_edges);
7631 if (loop->exits_doms)
7632 sbitmap_free (loop->exits_doms);
7634 free (loops->array);
7635 loops->array = NULL;
7638 sbitmap_vector_free (loops->cfg.dom);
7639 if (loops->cfg.dfs_order)
7640 free (loops->cfg.dfs_order);
7642 if (loops->shared_headers)
7643 sbitmap_free (loops->shared_headers);
7648 /* Find the entry edges into the loop with header HEADER and nodes
7649 NODES and store in ENTRY_EDGES array. Return the number of entry
7650 edges from the loop. */
7653 flow_loop_entry_edges_find (header, nodes, entry_edges)
7655 const sbitmap nodes;
7661 *entry_edges = NULL;
7664 for (e = header->pred; e; e = e->pred_next)
7666 basic_block src = e->src;
7668 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7675 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
7678 for (e = header->pred; e; e = e->pred_next)
7680 basic_block src = e->src;
7682 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7683 (*entry_edges)[num_entries++] = e;
7690 /* Find the exit edges from the loop using the bitmap of loop nodes
7691 NODES and store in EXIT_EDGES array. Return the number of
7692 exit edges from the loop. */
7695 flow_loop_exit_edges_find (nodes, exit_edges)
7696 const sbitmap nodes;
7705 /* Check all nodes within the loop to see if there are any
7706 successors not in the loop. Note that a node may have multiple
7707 exiting edges ????? A node can have one jumping edge and one fallthru
7708 edge so only one of these can exit the loop. */
7710 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7711 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7713 basic_block dest = e->dest;
7715 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7723 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
7725 /* Store all exiting edges into an array. */
7727 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7728 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7730 basic_block dest = e->dest;
7732 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7733 (*exit_edges)[num_exits++] = e;
7741 /* Find the nodes contained within the loop with header HEADER and
7742 latch LATCH and store in NODES. Return the number of nodes within
7746 flow_loop_nodes_find (header, latch, nodes)
7755 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
7758 /* Start with only the loop header in the set of loop nodes. */
7759 sbitmap_zero (nodes);
7760 SET_BIT (nodes, header->index);
7762 header->loop_depth++;
7764 /* Push the loop latch on to the stack. */
7765 if (! TEST_BIT (nodes, latch->index))
7767 SET_BIT (nodes, latch->index);
7768 latch->loop_depth++;
7770 stack[sp++] = latch;
7779 for (e = node->pred; e; e = e->pred_next)
7781 basic_block ancestor = e->src;
7783 /* If each ancestor not marked as part of loop, add to set of
7784 loop nodes and push on to stack. */
7785 if (ancestor != ENTRY_BLOCK_PTR
7786 && ! TEST_BIT (nodes, ancestor->index))
7788 SET_BIT (nodes, ancestor->index);
7789 ancestor->loop_depth++;
7791 stack[sp++] = ancestor;
7799 /* Compute the depth first search order and store in the array
7800 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7801 RC_ORDER is non-zero, return the reverse completion number for each
7802 node. Returns the number of nodes visited. A depth first search
7803 tries to get as far away from the starting point as quickly as
7807 flow_depth_first_order_compute (dfs_order, rc_order)
7814 int rcnum = n_basic_blocks - 1;
7817 /* Allocate stack for back-tracking up CFG. */
7818 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
7821 /* Allocate bitmap to track nodes that have been visited. */
7822 visited = sbitmap_alloc (n_basic_blocks);
7824 /* None of the nodes in the CFG have been visited yet. */
7825 sbitmap_zero (visited);
7827 /* Push the first edge on to the stack. */
7828 stack[sp++] = ENTRY_BLOCK_PTR->succ;
7836 /* Look at the edge on the top of the stack. */
7841 /* Check if the edge destination has been visited yet. */
7842 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
7844 /* Mark that we have visited the destination. */
7845 SET_BIT (visited, dest->index);
7848 dfs_order[dfsnum++] = dest->index;
7852 /* Since the DEST node has been visited for the first
7853 time, check its successors. */
7854 stack[sp++] = dest->succ;
7858 /* There are no successors for the DEST node so assign
7859 its reverse completion number. */
7861 rc_order[rcnum--] = dest->index;
7866 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
7868 /* There are no more successors for the SRC node
7869 so assign its reverse completion number. */
7871 rc_order[rcnum--] = src->index;
7875 stack[sp - 1] = e->succ_next;
7882 sbitmap_free (visited);
7884 /* The number of nodes visited should not be greater than
7886 if (dfsnum > n_basic_blocks)
7889 /* There are some nodes left in the CFG that are unreachable. */
7890 if (dfsnum < n_basic_blocks)
7895 /* Compute the depth first search order on the _reverse_ graph and
7896 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7897 Returns the number of nodes visited.
7899 The computation is split into three pieces:
7901 flow_dfs_compute_reverse_init () creates the necessary data
7904 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7905 structures. The block will start the search.
7907 flow_dfs_compute_reverse_execute () continues (or starts) the
7908 search using the block on the top of the stack, stopping when the
7911 flow_dfs_compute_reverse_finish () destroys the necessary data
7914 Thus, the user will probably call ..._init(), call ..._add_bb() to
7915 add a beginning basic block to the stack, call ..._execute(),
7916 possibly add another bb to the stack and again call ..._execute(),
7917 ..., and finally call _finish(). */
7919 /* Initialize the data structures used for depth-first search on the
7920 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7921 added to the basic block stack. DATA is the current depth-first
7922 search context. If INITIALIZE_STACK is non-zero, there is an
7923 element on the stack. */
7926 flow_dfs_compute_reverse_init (data)
7927 depth_first_search_ds data;
7929 /* Allocate stack for back-tracking up CFG. */
7931 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
7932 * sizeof (basic_block));
7935 /* Allocate bitmap to track nodes that have been visited. */
7936 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
7938 /* None of the nodes in the CFG have been visited yet. */
7939 sbitmap_zero (data->visited_blocks);
7944 /* Add the specified basic block to the top of the dfs data
7945 structures. When the search continues, it will start at the
7949 flow_dfs_compute_reverse_add_bb (data, bb)
7950 depth_first_search_ds data;
7953 data->stack[data->sp++] = bb;
7957 /* Continue the depth-first search through the reverse graph starting
7958 with the block at the stack's top and ending when the stack is
7959 empty. Visited nodes are marked. Returns an unvisited basic
7960 block, or NULL if there is none available. */
7963 flow_dfs_compute_reverse_execute (data)
7964 depth_first_search_ds data;
7970 while (data->sp > 0)
7972 bb = data->stack[--data->sp];
7974 /* Mark that we have visited this node. */
7975 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
7977 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
7979 /* Perform depth-first search on adjacent vertices. */
7980 for (e = bb->pred; e; e = e->pred_next)
7981 flow_dfs_compute_reverse_add_bb (data, e->src);
7985 /* Determine if there are unvisited basic blocks. */
7986 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
7987 if (!TEST_BIT (data->visited_blocks, i))
7988 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
7992 /* Destroy the data structures needed for depth-first search on the
7996 flow_dfs_compute_reverse_finish (data)
7997 depth_first_search_ds data;
8000 sbitmap_free (data->visited_blocks);
8005 /* Find the root node of the loop pre-header extended basic block and
8006 the edges along the trace from the root node to the loop header. */
8009 flow_loop_pre_header_scan (loop)
8015 loop->num_pre_header_edges = 0;
8017 if (loop->num_entries != 1)
8020 ebb = loop->entry_edges[0]->src;
8022 if (ebb != ENTRY_BLOCK_PTR)
8026 /* Count number of edges along trace from loop header to
8027 root of pre-header extended basic block. Usually this is
8028 only one or two edges. */
8030 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
8032 ebb = ebb->pred->src;
8036 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
8037 loop->num_pre_header_edges = num;
8039 /* Store edges in order that they are followed. The source
8040 of the first edge is the root node of the pre-header extended
8041 basic block and the destination of the last last edge is
8043 for (e = loop->entry_edges[0]; num; e = e->src->pred)
8045 loop->pre_header_edges[--num] = e;
8051 /* Return the block for the pre-header of the loop with header
8052 HEADER where DOM specifies the dominator information. Return NULL if
8053 there is no pre-header. */
8056 flow_loop_pre_header_find (header, dom)
8060 basic_block pre_header;
8063 /* If block p is a predecessor of the header and is the only block
8064 that the header does not dominate, then it is the pre-header. */
8066 for (e = header->pred; e; e = e->pred_next)
8068 basic_block node = e->src;
8070 if (node != ENTRY_BLOCK_PTR
8071 && ! TEST_BIT (dom[node->index], header->index))
8073 if (pre_header == NULL)
8077 /* There are multiple edges into the header from outside
8078 the loop so there is no pre-header block. */
8087 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
8088 previously added. The insertion algorithm assumes that the loops
8089 are added in the order found by a depth first search of the CFG. */
8092 flow_loop_tree_node_add (prevloop, loop)
8093 struct loop *prevloop;
8097 if (flow_loop_nested_p (prevloop, loop))
8099 prevloop->inner = loop;
8100 loop->outer = prevloop;
8104 while (prevloop->outer)
8106 if (flow_loop_nested_p (prevloop->outer, loop))
8108 prevloop->next = loop;
8109 loop->outer = prevloop->outer;
8112 prevloop = prevloop->outer;
8115 prevloop->next = loop;
8119 /* Build the loop hierarchy tree for LOOPS. */
8122 flow_loops_tree_build (loops)
8123 struct loops *loops;
8128 num_loops = loops->num;
8132 /* Root the loop hierarchy tree with the first loop found.
8133 Since we used a depth first search this should be the
8135 loops->tree = &loops->array[0];
8136 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
8138 /* Add the remaining loops to the tree. */
8139 for (i = 1; i < num_loops; i++)
8140 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
8143 /* Helper function to compute loop nesting depth and enclosed loop level
8144 for the natural loop specified by LOOP at the loop depth DEPTH.
8145 Returns the loop level. */
8148 flow_loop_level_compute (loop, depth)
8158 /* Traverse loop tree assigning depth and computing level as the
8159 maximum level of all the inner loops of this loop. The loop
8160 level is equivalent to the height of the loop in the loop tree
8161 and corresponds to the number of enclosed loop levels (including
8163 for (inner = loop->inner; inner; inner = inner->next)
8167 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
8172 loop->level = level;
8173 loop->depth = depth;
8177 /* Compute the loop nesting depth and enclosed loop level for the loop
8178 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
8182 flow_loops_level_compute (loops)
8183 struct loops *loops;
8189 /* Traverse all the outer level loops. */
8190 for (loop = loops->tree; loop; loop = loop->next)
8192 level = flow_loop_level_compute (loop, 1);
8200 /* Scan a single natural loop specified by LOOP collecting information
8201 about it specified by FLAGS. */
8204 flow_loop_scan (loops, loop, flags)
8205 struct loops *loops;
8209 /* Determine prerequisites. */
8210 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
8211 flags |= LOOP_EXIT_EDGES;
8213 if (flags & LOOP_ENTRY_EDGES)
8215 /* Find edges which enter the loop header.
8216 Note that the entry edges should only
8217 enter the header of a natural loop. */
8219 = flow_loop_entry_edges_find (loop->header,
8221 &loop->entry_edges);
8224 if (flags & LOOP_EXIT_EDGES)
8226 /* Find edges which exit the loop. */
8228 = flow_loop_exit_edges_find (loop->nodes,
8232 if (flags & LOOP_EXITS_DOMS)
8236 /* Determine which loop nodes dominate all the exits
8238 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8239 sbitmap_copy (loop->exits_doms, loop->nodes);
8240 for (j = 0; j < loop->num_exits; j++)
8241 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8242 loops->cfg.dom[loop->exit_edges[j]->src->index]);
8244 /* The header of a natural loop must dominate
8246 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8250 if (flags & LOOP_PRE_HEADER)
8252 /* Look to see if the loop has a pre-header node. */
8254 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
8256 /* Find the blocks within the extended basic block of
8257 the loop pre-header. */
8258 flow_loop_pre_header_scan (loop);
8264 /* Find all the natural loops in the function and save in LOOPS structure
8265 and recalculate loop_depth information in basic block structures.
8266 FLAGS controls which loop information is collected.
8267 Return the number of natural loops found. */
8270 flow_loops_find (loops, flags)
8271 struct loops *loops;
8283 /* This function cannot be repeatedly called with different
8284 flags to build up the loop information. The loop tree
8285 must always be built if this function is called. */
8286 if (! (flags & LOOP_TREE))
8289 memset (loops, 0, sizeof (*loops));
8291 /* Taking care of this degenerate case makes the rest of
8292 this code simpler. */
8293 if (n_basic_blocks == 0)
8299 /* Compute the dominators. */
8300 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8301 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
8303 /* Count the number of loop edges (back edges). This should be the
8304 same as the number of natural loops. */
8307 for (b = 0; b < n_basic_blocks; b++)
8311 header = BASIC_BLOCK (b);
8312 header->loop_depth = 0;
8314 for (e = header->pred; e; e = e->pred_next)
8316 basic_block latch = e->src;
8318 /* Look for back edges where a predecessor is dominated
8319 by this block. A natural loop has a single entry
8320 node (header) that dominates all the nodes in the
8321 loop. It also has single back edge to the header
8322 from a latch node. Note that multiple natural loops
8323 may share the same header. */
8324 if (b != header->index)
8327 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8334 /* Compute depth first search order of the CFG so that outer
8335 natural loops will be found before inner natural loops. */
8336 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8337 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8338 flow_depth_first_order_compute (dfs_order, rc_order);
8340 /* Save CFG derived information to avoid recomputing it. */
8341 loops->cfg.dom = dom;
8342 loops->cfg.dfs_order = dfs_order;
8343 loops->cfg.rc_order = rc_order;
8345 /* Allocate loop structures. */
8347 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8349 headers = sbitmap_alloc (n_basic_blocks);
8350 sbitmap_zero (headers);
8352 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8353 sbitmap_zero (loops->shared_headers);
8355 /* Find and record information about all the natural loops
8358 for (b = 0; b < n_basic_blocks; b++)
8362 /* Search the nodes of the CFG in reverse completion order
8363 so that we can find outer loops first. */
8364 header = BASIC_BLOCK (rc_order[b]);
8366 /* Look for all the possible latch blocks for this header. */
8367 for (e = header->pred; e; e = e->pred_next)
8369 basic_block latch = e->src;
8371 /* Look for back edges where a predecessor is dominated
8372 by this block. A natural loop has a single entry
8373 node (header) that dominates all the nodes in the
8374 loop. It also has single back edge to the header
8375 from a latch node. Note that multiple natural loops
8376 may share the same header. */
8377 if (latch != ENTRY_BLOCK_PTR
8378 && TEST_BIT (dom[latch->index], header->index))
8382 loop = loops->array + num_loops;
8384 loop->header = header;
8385 loop->latch = latch;
8386 loop->num = num_loops;
8393 for (i = 0; i < num_loops; i++)
8395 struct loop *loop = &loops->array[i];
8397 /* Keep track of blocks that are loop headers so
8398 that we can tell which loops should be merged. */
8399 if (TEST_BIT (headers, loop->header->index))
8400 SET_BIT (loops->shared_headers, loop->header->index);
8401 SET_BIT (headers, loop->header->index);
8403 /* Find nodes contained within the loop. */
8404 loop->nodes = sbitmap_alloc (n_basic_blocks);
8406 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8408 /* Compute first and last blocks within the loop.
8409 These are often the same as the loop header and
8410 loop latch respectively, but this is not always
8413 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
8415 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
8417 flow_loop_scan (loops, loop, flags);
8420 /* Natural loops with shared headers may either be disjoint or
8421 nested. Disjoint loops with shared headers cannot be inner
8422 loops and should be merged. For now just mark loops that share
8424 for (i = 0; i < num_loops; i++)
8425 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
8426 loops->array[i].shared = 1;
8428 sbitmap_free (headers);
8431 loops->num = num_loops;
8433 /* Build the loop hierarchy tree. */
8434 flow_loops_tree_build (loops);
8436 /* Assign the loop nesting depth and enclosed loop level for each
8438 loops->levels = flow_loops_level_compute (loops);
8444 /* Update the information regarding the loops in the CFG
8445 specified by LOOPS. */
8447 flow_loops_update (loops, flags)
8448 struct loops *loops;
8451 /* One day we may want to update the current loop data. For now
8452 throw away the old stuff and rebuild what we need. */
8454 flow_loops_free (loops);
8456 return flow_loops_find (loops, flags);
8460 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
8463 flow_loop_outside_edge_p (loop, e)
8464 const struct loop *loop;
8467 if (e->dest != loop->header)
8469 return (e->src == ENTRY_BLOCK_PTR)
8470 || ! TEST_BIT (loop->nodes, e->src->index);
8473 /* Clear LOG_LINKS fields of insns in a chain.
8474 Also clear the global_live_at_{start,end} fields of the basic block
8478 clear_log_links (insns)
8484 for (i = insns; i; i = NEXT_INSN (i))
8488 for (b = 0; b < n_basic_blocks; b++)
8490 basic_block bb = BASIC_BLOCK (b);
8492 bb->global_live_at_start = NULL;
8493 bb->global_live_at_end = NULL;
8496 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
8497 EXIT_BLOCK_PTR->global_live_at_start = NULL;
8500 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
8501 correspond to the hard registers, if any, set in that map. This
8502 could be done far more efficiently by having all sorts of special-cases
8503 with moving single words, but probably isn't worth the trouble. */
8506 reg_set_to_hard_reg_set (to, from)
8512 EXECUTE_IF_SET_IN_BITMAP
8515 if (i >= FIRST_PSEUDO_REGISTER)
8517 SET_HARD_REG_BIT (*to, i);
8521 /* Called once at intialization time. */
8526 static int initialized;
8530 gcc_obstack_init (&flow_obstack);
8531 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
8536 obstack_free (&flow_obstack, flow_firstobj);
8537 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);