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 which 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 /* We work through the queue until there are no more blocks. What
3389 is live at the end of this block is precisely the union of what
3390 is live at the beginning of all its successors. So, we set its
3391 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
3392 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
3393 this block by walking through the instructions in this block in
3394 reverse order and updating as we go. If that changed
3395 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
3396 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
3398 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
3399 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
3400 must either be live at the end of the block, or used within the
3401 block. In the latter case, it will certainly never disappear
3402 from GLOBAL_LIVE_AT_START. In the former case, the register
3403 could go away only if it disappeared from GLOBAL_LIVE_AT_START
3404 for one of the successor blocks. By induction, that cannot
3406 while (qhead != qtail)
3408 int rescan, changed;
3417 /* Begin by propagating live_at_start from the successor blocks. */
3418 CLEAR_REG_SET (new_live_at_end);
3419 for (e = bb->succ; e; e = e->succ_next)
3421 basic_block sb = e->dest;
3423 /* Call-clobbered registers die across exception and call edges. */
3424 /* ??? Abnormal call edges ignored for the moment, as this gets
3425 confused by sibling call edges, which crashes reg-stack. */
3426 if (e->flags & EDGE_EH)
3428 bitmap_operation (tmp, sb->global_live_at_start,
3429 call_used, BITMAP_AND_COMPL);
3430 IOR_REG_SET (new_live_at_end, tmp);
3433 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3436 /* The all-important stack pointer must always be live. */
3437 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3439 /* Before reload, there are a few registers that must be forced
3440 live everywhere -- which might not already be the case for
3441 blocks within infinite loops. */
3442 if (! reload_completed)
3444 /* Any reference to any pseudo before reload is a potential
3445 reference of the frame pointer. */
3446 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3448 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3449 /* Pseudos with argument area equivalences may require
3450 reloading via the argument pointer. */
3451 if (fixed_regs[ARG_POINTER_REGNUM])
3452 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
3455 /* Any constant, or pseudo with constant equivalences, may
3456 require reloading from memory using the pic register. */
3457 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3458 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3459 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
3462 /* Regs used in phi nodes are not included in
3463 global_live_at_start, since they are live only along a
3464 particular edge. Set those regs that are live because of a
3465 phi node alternative corresponding to this particular block. */
3467 for_each_successor_phi (bb, &set_phi_alternative_reg,
3470 if (bb == ENTRY_BLOCK_PTR)
3472 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3476 /* On our first pass through this block, we'll go ahead and continue.
3477 Recognize first pass by local_set NULL. On subsequent passes, we
3478 get to skip out early if live_at_end wouldn't have changed. */
3480 if (bb->local_set == NULL)
3482 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3483 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3488 /* If any bits were removed from live_at_end, we'll have to
3489 rescan the block. This wouldn't be necessary if we had
3490 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3491 local_live is really dependent on live_at_end. */
3492 CLEAR_REG_SET (tmp);
3493 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3494 new_live_at_end, BITMAP_AND_COMPL);
3498 /* If any of the registers in the new live_at_end set are
3499 conditionally set in this basic block, we must rescan.
3500 This is because conditional lifetimes at the end of the
3501 block do not just take the live_at_end set into account,
3502 but also the liveness at the start of each successor
3503 block. We can miss changes in those sets if we only
3504 compare the new live_at_end against the previous one. */
3505 CLEAR_REG_SET (tmp);
3506 rescan = bitmap_operation (tmp, new_live_at_end,
3507 bb->cond_local_set, BITMAP_AND);
3512 /* Find the set of changed bits. Take this opportunity
3513 to notice that this set is empty and early out. */
3514 CLEAR_REG_SET (tmp);
3515 changed = bitmap_operation (tmp, bb->global_live_at_end,
3516 new_live_at_end, BITMAP_XOR);
3520 /* If any of the changed bits overlap with local_set,
3521 we'll have to rescan the block. Detect overlap by
3522 the AND with ~local_set turning off bits. */
3523 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3528 /* Let our caller know that BB changed enough to require its
3529 death notes updated. */
3531 SET_BIT (blocks_out, bb->index);
3535 /* Add to live_at_start the set of all registers in
3536 new_live_at_end that aren't in the old live_at_end. */
3538 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3540 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3542 changed = bitmap_operation (bb->global_live_at_start,
3543 bb->global_live_at_start,
3550 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3552 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3553 into live_at_start. */
3554 propagate_block (bb, new_live_at_end, bb->local_set,
3555 bb->cond_local_set, flags);
3557 /* If live_at start didn't change, no need to go farther. */
3558 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3561 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3564 /* Queue all predecessors of BB so that we may re-examine
3565 their live_at_end. */
3566 for (e = bb->pred; e; e = e->pred_next)
3568 basic_block pb = e->src;
3569 if (pb->aux == NULL)
3580 FREE_REG_SET (new_live_at_end);
3581 FREE_REG_SET (call_used);
3585 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3587 basic_block bb = BASIC_BLOCK (i);
3588 FREE_REG_SET (bb->local_set);
3589 FREE_REG_SET (bb->cond_local_set);
3594 for (i = n_basic_blocks - 1; i >= 0; --i)
3596 basic_block bb = BASIC_BLOCK (i);
3597 FREE_REG_SET (bb->local_set);
3598 FREE_REG_SET (bb->cond_local_set);
3605 /* Subroutines of life analysis. */
3607 /* Allocate the permanent data structures that represent the results
3608 of life analysis. Not static since used also for stupid life analysis. */
3611 allocate_bb_life_data ()
3615 for (i = 0; i < n_basic_blocks; i++)
3617 basic_block bb = BASIC_BLOCK (i);
3619 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3620 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3623 ENTRY_BLOCK_PTR->global_live_at_end
3624 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3625 EXIT_BLOCK_PTR->global_live_at_start
3626 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3628 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3632 allocate_reg_life_data ()
3636 max_regno = max_reg_num ();
3638 /* Recalculate the register space, in case it has grown. Old style
3639 vector oriented regsets would set regset_{size,bytes} here also. */
3640 allocate_reg_info (max_regno, FALSE, FALSE);
3642 /* Reset all the data we'll collect in propagate_block and its
3644 for (i = 0; i < max_regno; i++)
3648 REG_N_DEATHS (i) = 0;
3649 REG_N_CALLS_CROSSED (i) = 0;
3650 REG_LIVE_LENGTH (i) = 0;
3651 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3655 /* Delete dead instructions for propagate_block. */
3658 propagate_block_delete_insn (bb, insn)
3662 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3664 /* If the insn referred to a label, and that label was attached to
3665 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3666 pretty much mandatory to delete it, because the ADDR_VEC may be
3667 referencing labels that no longer exist.
3669 INSN may reference a deleted label, particularly when a jump
3670 table has been optimized into a direct jump. There's no
3671 real good way to fix up the reference to the deleted label
3672 when the label is deleted, so we just allow it here.
3674 After dead code elimination is complete, we do search for
3675 any REG_LABEL notes which reference deleted labels as a
3678 if (inote && GET_CODE (inote) == CODE_LABEL)
3680 rtx label = XEXP (inote, 0);
3683 /* The label may be forced if it has been put in the constant
3684 pool. If that is the only use we must discard the table
3685 jump following it, but not the label itself. */
3686 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
3687 && (next = next_nonnote_insn (label)) != NULL
3688 && GET_CODE (next) == JUMP_INSN
3689 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3690 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3692 rtx pat = PATTERN (next);
3693 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3694 int len = XVECLEN (pat, diff_vec_p);
3697 for (i = 0; i < len; i++)
3698 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3700 flow_delete_insn (next);
3704 if (bb->end == insn)
3705 bb->end = PREV_INSN (insn);
3706 flow_delete_insn (insn);
3709 /* Delete dead libcalls for propagate_block. Return the insn
3710 before the libcall. */
3713 propagate_block_delete_libcall (bb, insn, note)
3717 rtx first = XEXP (note, 0);
3718 rtx before = PREV_INSN (first);
3720 if (insn == bb->end)
3723 flow_delete_insn_chain (first, insn);
3727 /* Update the life-status of regs for one insn. Return the previous insn. */
3730 propagate_one_insn (pbi, insn)
3731 struct propagate_block_info *pbi;
3734 rtx prev = PREV_INSN (insn);
3735 int flags = pbi->flags;
3736 int insn_is_dead = 0;
3737 int libcall_is_dead = 0;
3741 if (! INSN_P (insn))
3744 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3745 if (flags & PROP_SCAN_DEAD_CODE)
3747 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
3748 libcall_is_dead = (insn_is_dead && note != 0
3749 && libcall_dead_p (pbi, note, insn));
3752 /* If an instruction consists of just dead store(s) on final pass,
3754 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3756 /* If we're trying to delete a prologue or epilogue instruction
3757 that isn't flagged as possibly being dead, something is wrong.
3758 But if we are keeping the stack pointer depressed, we might well
3759 be deleting insns that are used to compute the amount to update
3760 it by, so they are fine. */
3761 if (reload_completed
3762 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
3763 && (TYPE_RETURNS_STACK_DEPRESSED
3764 (TREE_TYPE (current_function_decl))))
3765 && (((HAVE_epilogue || HAVE_prologue)
3766 && prologue_epilogue_contains (insn))
3767 || (HAVE_sibcall_epilogue
3768 && sibcall_epilogue_contains (insn)))
3769 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
3772 /* Record sets. Do this even for dead instructions, since they
3773 would have killed the values if they hadn't been deleted. */
3774 mark_set_regs (pbi, PATTERN (insn), insn);
3776 /* CC0 is now known to be dead. Either this insn used it,
3777 in which case it doesn't anymore, or clobbered it,
3778 so the next insn can't use it. */
3781 if (libcall_is_dead)
3782 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
3784 propagate_block_delete_insn (pbi->bb, insn);
3789 /* See if this is an increment or decrement that can be merged into
3790 a following memory address. */
3793 register rtx x = single_set (insn);
3795 /* Does this instruction increment or decrement a register? */
3796 if ((flags & PROP_AUTOINC)
3798 && GET_CODE (SET_DEST (x)) == REG
3799 && (GET_CODE (SET_SRC (x)) == PLUS
3800 || GET_CODE (SET_SRC (x)) == MINUS)
3801 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3802 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3803 /* Ok, look for a following memory ref we can combine with.
3804 If one is found, change the memory ref to a PRE_INC
3805 or PRE_DEC, cancel this insn, and return 1.
3806 Return 0 if nothing has been done. */
3807 && try_pre_increment_1 (pbi, insn))
3810 #endif /* AUTO_INC_DEC */
3812 CLEAR_REG_SET (pbi->new_set);
3814 /* If this is not the final pass, and this insn is copying the value of
3815 a library call and it's dead, don't scan the insns that perform the
3816 library call, so that the call's arguments are not marked live. */
3817 if (libcall_is_dead)
3819 /* Record the death of the dest reg. */
3820 mark_set_regs (pbi, PATTERN (insn), insn);
3822 insn = XEXP (note, 0);
3823 return PREV_INSN (insn);
3825 else if (GET_CODE (PATTERN (insn)) == SET
3826 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3827 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3828 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3829 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3830 /* We have an insn to pop a constant amount off the stack.
3831 (Such insns use PLUS regardless of the direction of the stack,
3832 and any insn to adjust the stack by a constant is always a pop.)
3833 These insns, if not dead stores, have no effect on life. */
3837 /* Any regs live at the time of a call instruction must not go
3838 in a register clobbered by calls. Find all regs now live and
3839 record this for them. */
3841 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
3842 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3843 { REG_N_CALLS_CROSSED (i)++; });
3845 /* Record sets. Do this even for dead instructions, since they
3846 would have killed the values if they hadn't been deleted. */
3847 mark_set_regs (pbi, PATTERN (insn), insn);
3849 if (GET_CODE (insn) == CALL_INSN)
3855 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3856 cond = COND_EXEC_TEST (PATTERN (insn));
3858 /* Non-constant calls clobber memory. */
3859 if (! CONST_CALL_P (insn))
3861 free_EXPR_LIST_list (&pbi->mem_set_list);
3862 pbi->mem_set_list_len = 0;
3865 /* There may be extra registers to be clobbered. */
3866 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3868 note = XEXP (note, 1))
3869 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
3870 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
3871 cond, insn, pbi->flags);
3873 /* Calls change all call-used and global registers. */
3874 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3875 if (call_used_regs[i] && ! global_regs[i]
3878 /* We do not want REG_UNUSED notes for these registers. */
3879 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
3881 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
3885 /* If an insn doesn't use CC0, it becomes dead since we assume
3886 that every insn clobbers it. So show it dead here;
3887 mark_used_regs will set it live if it is referenced. */
3892 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
3894 /* Sometimes we may have inserted something before INSN (such as a move)
3895 when we make an auto-inc. So ensure we will scan those insns. */
3897 prev = PREV_INSN (insn);
3900 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3906 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3907 cond = COND_EXEC_TEST (PATTERN (insn));
3909 /* Calls use their arguments. */
3910 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3912 note = XEXP (note, 1))
3913 if (GET_CODE (XEXP (note, 0)) == USE)
3914 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
3917 /* The stack ptr is used (honorarily) by a CALL insn. */
3918 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
3920 /* Calls may also reference any of the global registers,
3921 so they are made live. */
3922 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3924 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
3929 /* On final pass, update counts of how many insns in which each reg
3931 if (flags & PROP_REG_INFO)
3932 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3933 { REG_LIVE_LENGTH (i)++; });
3938 /* Initialize a propagate_block_info struct for public consumption.
3939 Note that the structure itself is opaque to this file, but that
3940 the user can use the regsets provided here. */
3942 struct propagate_block_info *
3943 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
3945 regset live, local_set, cond_local_set;
3948 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
3951 pbi->reg_live = live;
3952 pbi->mem_set_list = NULL_RTX;
3953 pbi->mem_set_list_len = 0;
3954 pbi->local_set = local_set;
3955 pbi->cond_local_set = cond_local_set;
3959 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3960 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
3962 pbi->reg_next_use = NULL;
3964 pbi->new_set = BITMAP_XMALLOC ();
3966 #ifdef HAVE_conditional_execution
3967 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
3968 free_reg_cond_life_info);
3969 pbi->reg_cond_reg = BITMAP_XMALLOC ();
3971 /* If this block ends in a conditional branch, for each register live
3972 from one side of the branch and not the other, record the register
3973 as conditionally dead. */
3974 if (GET_CODE (bb->end) == JUMP_INSN
3975 && any_condjump_p (bb->end))
3977 regset_head diff_head;
3978 regset diff = INITIALIZE_REG_SET (diff_head);
3979 basic_block bb_true, bb_false;
3980 rtx cond_true, cond_false, set_src;
3983 /* Identify the successor blocks. */
3984 bb_true = bb->succ->dest;
3985 if (bb->succ->succ_next != NULL)
3987 bb_false = bb->succ->succ_next->dest;
3989 if (bb->succ->flags & EDGE_FALLTHRU)
3991 basic_block t = bb_false;
3995 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
4000 /* This can happen with a conditional jump to the next insn. */
4001 if (JUMP_LABEL (bb->end) != bb_true->head)
4004 /* Simplest way to do nothing. */
4008 /* Extract the condition from the branch. */
4009 set_src = SET_SRC (pc_set (bb->end));
4010 cond_true = XEXP (set_src, 0);
4011 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
4012 GET_MODE (cond_true), XEXP (cond_true, 0),
4013 XEXP (cond_true, 1));
4014 if (GET_CODE (XEXP (set_src, 1)) == PC)
4017 cond_false = cond_true;
4021 /* Compute which register lead different lives in the successors. */
4022 if (bitmap_operation (diff, bb_true->global_live_at_start,
4023 bb_false->global_live_at_start, BITMAP_XOR))
4025 rtx reg = XEXP (cond_true, 0);
4027 if (GET_CODE (reg) == SUBREG)
4028 reg = SUBREG_REG (reg);
4030 if (GET_CODE (reg) != REG)
4033 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
4035 /* For each such register, mark it conditionally dead. */
4036 EXECUTE_IF_SET_IN_REG_SET
4039 struct reg_cond_life_info *rcli;
4042 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4044 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
4048 rcli->condition = cond;
4049 rcli->stores = const0_rtx;
4050 rcli->orig_condition = cond;
4052 splay_tree_insert (pbi->reg_cond_dead, i,
4053 (splay_tree_value) rcli);
4057 FREE_REG_SET (diff);
4061 /* If this block has no successors, any stores to the frame that aren't
4062 used later in the block are dead. So make a pass over the block
4063 recording any such that are made and show them dead at the end. We do
4064 a very conservative and simple job here. */
4066 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4067 && (TYPE_RETURNS_STACK_DEPRESSED
4068 (TREE_TYPE (current_function_decl))))
4069 && (flags & PROP_SCAN_DEAD_CODE)
4070 && (bb->succ == NULL
4071 || (bb->succ->succ_next == NULL
4072 && bb->succ->dest == EXIT_BLOCK_PTR
4073 && ! current_function_calls_eh_return)))
4076 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
4077 if (GET_CODE (insn) == INSN
4078 && (set = single_set (insn))
4079 && GET_CODE (SET_DEST (set)) == MEM)
4081 rtx mem = SET_DEST (set);
4082 rtx canon_mem = canon_rtx (mem);
4084 /* This optimization is performed by faking a store to the
4085 memory at the end of the block. This doesn't work for
4086 unchanging memories because multiple stores to unchanging
4087 memory is illegal and alias analysis doesn't consider it. */
4088 if (RTX_UNCHANGING_P (canon_mem))
4091 if (XEXP (canon_mem, 0) == frame_pointer_rtx
4092 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
4093 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
4094 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
4097 /* Store a copy of mem, otherwise the address may be scrogged
4098 by find_auto_inc. This matters because insn_dead_p uses
4099 an rtx_equal_p check to determine if two addresses are
4100 the same. This works before find_auto_inc, but fails
4101 after find_auto_inc, causing discrepencies between the
4102 set of live registers calculated during the
4103 calculate_global_regs_live phase and what actually exists
4104 after flow completes, leading to aborts. */
4105 if (flags & PROP_AUTOINC)
4106 mem = shallow_copy_rtx (mem);
4108 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
4109 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
4118 /* Release a propagate_block_info struct. */
4121 free_propagate_block_info (pbi)
4122 struct propagate_block_info *pbi;
4124 free_EXPR_LIST_list (&pbi->mem_set_list);
4126 BITMAP_XFREE (pbi->new_set);
4128 #ifdef HAVE_conditional_execution
4129 splay_tree_delete (pbi->reg_cond_dead);
4130 BITMAP_XFREE (pbi->reg_cond_reg);
4133 if (pbi->reg_next_use)
4134 free (pbi->reg_next_use);
4139 /* Compute the registers live at the beginning of a basic block BB from
4140 those live at the end.
4142 When called, REG_LIVE contains those live at the end. On return, it
4143 contains those live at the beginning.
4145 LOCAL_SET, if non-null, will be set with all registers killed
4146 unconditionally by this basic block.
4147 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
4148 killed conditionally by this basic block. If there is any unconditional
4149 set of a register, then the corresponding bit will be set in LOCAL_SET
4150 and cleared in COND_LOCAL_SET.
4151 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
4152 case, the resulting set will be equal to the union of the two sets that
4153 would otherwise be computed. */
4156 propagate_block (bb, live, local_set, cond_local_set, flags)
4160 regset cond_local_set;
4163 struct propagate_block_info *pbi;
4166 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
4168 if (flags & PROP_REG_INFO)
4172 /* Process the regs live at the end of the block.
4173 Mark them as not local to any one basic block. */
4174 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
4175 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4178 /* Scan the block an insn at a time from end to beginning. */
4180 for (insn = bb->end;; insn = prev)
4182 /* If this is a call to `setjmp' et al, warn if any
4183 non-volatile datum is live. */
4184 if ((flags & PROP_REG_INFO)
4185 && GET_CODE (insn) == NOTE
4186 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
4187 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
4189 prev = propagate_one_insn (pbi, insn);
4191 if (insn == bb->head)
4195 free_propagate_block_info (pbi);
4198 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
4199 (SET expressions whose destinations are registers dead after the insn).
4200 NEEDED is the regset that says which regs are alive after the insn.
4202 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
4204 If X is the entire body of an insn, NOTES contains the reg notes
4205 pertaining to the insn. */
4208 insn_dead_p (pbi, x, call_ok, notes)
4209 struct propagate_block_info *pbi;
4212 rtx notes ATTRIBUTE_UNUSED;
4214 enum rtx_code code = GET_CODE (x);
4217 /* If flow is invoked after reload, we must take existing AUTO_INC
4218 expresions into account. */
4219 if (reload_completed)
4221 for (; notes; notes = XEXP (notes, 1))
4223 if (REG_NOTE_KIND (notes) == REG_INC)
4225 int regno = REGNO (XEXP (notes, 0));
4227 /* Don't delete insns to set global regs. */
4228 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4229 || REGNO_REG_SET_P (pbi->reg_live, regno))
4236 /* If setting something that's a reg or part of one,
4237 see if that register's altered value will be live. */
4241 rtx r = SET_DEST (x);
4244 if (GET_CODE (r) == CC0)
4245 return ! pbi->cc0_live;
4248 /* A SET that is a subroutine call cannot be dead. */
4249 if (GET_CODE (SET_SRC (x)) == CALL)
4255 /* Don't eliminate loads from volatile memory or volatile asms. */
4256 else if (volatile_refs_p (SET_SRC (x)))
4259 if (GET_CODE (r) == MEM)
4263 if (MEM_VOLATILE_P (r))
4266 /* Walk the set of memory locations we are currently tracking
4267 and see if one is an identical match to this memory location.
4268 If so, this memory write is dead (remember, we're walking
4269 backwards from the end of the block to the start). Since
4270 rtx_equal_p does not check the alias set or flags, we also
4271 must have the potential for them to conflict (anti_dependence). */
4272 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
4273 if (anti_dependence (r, XEXP (temp, 0)))
4275 rtx mem = XEXP (temp, 0);
4277 if (rtx_equal_p (mem, r))
4280 /* Check if memory reference matches an auto increment. Only
4281 post increment/decrement or modify are valid. */
4282 if (GET_MODE (mem) == GET_MODE (r)
4283 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4284 || GET_CODE (XEXP (mem, 0)) == POST_INC
4285 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4286 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4287 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4294 while (GET_CODE (r) == SUBREG
4295 || GET_CODE (r) == STRICT_LOW_PART
4296 || GET_CODE (r) == ZERO_EXTRACT)
4299 if (GET_CODE (r) == REG)
4301 int regno = REGNO (r);
4304 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4307 /* If this is a hard register, verify that subsequent
4308 words are not needed. */
4309 if (regno < FIRST_PSEUDO_REGISTER)
4311 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4314 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4318 /* Don't delete insns to set global regs. */
4319 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4322 /* Make sure insns to set the stack pointer aren't deleted. */
4323 if (regno == STACK_POINTER_REGNUM)
4326 /* ??? These bits might be redundant with the force live bits
4327 in calculate_global_regs_live. We would delete from
4328 sequential sets; whether this actually affects real code
4329 for anything but the stack pointer I don't know. */
4330 /* Make sure insns to set the frame pointer aren't deleted. */
4331 if (regno == FRAME_POINTER_REGNUM
4332 && (! reload_completed || frame_pointer_needed))
4334 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4335 if (regno == HARD_FRAME_POINTER_REGNUM
4336 && (! reload_completed || frame_pointer_needed))
4340 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4341 /* Make sure insns to set arg pointer are never deleted
4342 (if the arg pointer isn't fixed, there will be a USE
4343 for it, so we can treat it normally). */
4344 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4348 /* Otherwise, the set is dead. */
4354 /* If performing several activities, insn is dead if each activity
4355 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4356 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4358 else if (code == PARALLEL)
4360 int i = XVECLEN (x, 0);
4362 for (i--; i >= 0; i--)
4363 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4364 && GET_CODE (XVECEXP (x, 0, i)) != USE
4365 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4371 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4372 is not necessarily true for hard registers. */
4373 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4374 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4375 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4378 /* We do not check other CLOBBER or USE here. An insn consisting of just
4379 a CLOBBER or just a USE should not be deleted. */
4383 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4384 return 1 if the entire library call is dead.
4385 This is true if INSN copies a register (hard or pseudo)
4386 and if the hard return reg of the call insn is dead.
4387 (The caller should have tested the destination of the SET inside
4388 INSN already for death.)
4390 If this insn doesn't just copy a register, then we don't
4391 have an ordinary libcall. In that case, cse could not have
4392 managed to substitute the source for the dest later on,
4393 so we can assume the libcall is dead.
4395 PBI is the block info giving pseudoregs live before this insn.
4396 NOTE is the REG_RETVAL note of the insn. */
4399 libcall_dead_p (pbi, note, insn)
4400 struct propagate_block_info *pbi;
4404 rtx x = single_set (insn);
4408 register rtx r = SET_SRC (x);
4409 if (GET_CODE (r) == REG)
4411 rtx call = XEXP (note, 0);
4415 /* Find the call insn. */
4416 while (call != insn && GET_CODE (call) != CALL_INSN)
4417 call = NEXT_INSN (call);
4419 /* If there is none, do nothing special,
4420 since ordinary death handling can understand these insns. */
4424 /* See if the hard reg holding the value is dead.
4425 If this is a PARALLEL, find the call within it. */
4426 call_pat = PATTERN (call);
4427 if (GET_CODE (call_pat) == PARALLEL)
4429 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4430 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4431 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4434 /* This may be a library call that is returning a value
4435 via invisible pointer. Do nothing special, since
4436 ordinary death handling can understand these insns. */
4440 call_pat = XVECEXP (call_pat, 0, i);
4443 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4449 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4450 live at function entry. Don't count global register variables, variables
4451 in registers that can be used for function arg passing, or variables in
4452 fixed hard registers. */
4455 regno_uninitialized (regno)
4458 if (n_basic_blocks == 0
4459 || (regno < FIRST_PSEUDO_REGISTER
4460 && (global_regs[regno]
4461 || fixed_regs[regno]
4462 || FUNCTION_ARG_REGNO_P (regno))))
4465 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
4468 /* 1 if register REGNO was alive at a place where `setjmp' was called
4469 and was set more than once or is an argument.
4470 Such regs may be clobbered by `longjmp'. */
4473 regno_clobbered_at_setjmp (regno)
4476 if (n_basic_blocks == 0)
4479 return ((REG_N_SETS (regno) > 1
4480 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
4481 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
4484 /* INSN references memory, possibly using autoincrement addressing modes.
4485 Find any entries on the mem_set_list that need to be invalidated due
4486 to an address change. */
4489 invalidate_mems_from_autoinc (pbi, insn)
4490 struct propagate_block_info *pbi;
4493 rtx note = REG_NOTES (insn);
4494 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
4496 if (REG_NOTE_KIND (note) == REG_INC)
4498 rtx temp = pbi->mem_set_list;
4499 rtx prev = NULL_RTX;
4504 next = XEXP (temp, 1);
4505 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
4507 /* Splice temp out of list. */
4509 XEXP (prev, 1) = next;
4511 pbi->mem_set_list = next;
4512 free_EXPR_LIST_node (temp);
4513 pbi->mem_set_list_len--;
4523 /* EXP is either a MEM or a REG. Remove any dependant entries
4524 from pbi->mem_set_list. */
4527 invalidate_mems_from_set (pbi, exp)
4528 struct propagate_block_info *pbi;
4531 rtx temp = pbi->mem_set_list;
4532 rtx prev = NULL_RTX;
4537 next = XEXP (temp, 1);
4538 if ((GET_CODE (exp) == MEM
4539 && output_dependence (XEXP (temp, 0), exp))
4540 || (GET_CODE (exp) == REG
4541 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
4543 /* Splice this entry out of the list. */
4545 XEXP (prev, 1) = next;
4547 pbi->mem_set_list = next;
4548 free_EXPR_LIST_node (temp);
4549 pbi->mem_set_list_len--;
4557 /* Process the registers that are set within X. Their bits are set to
4558 1 in the regset DEAD, because they are dead prior to this insn.
4560 If INSN is nonzero, it is the insn being processed.
4562 FLAGS is the set of operations to perform. */
4565 mark_set_regs (pbi, x, insn)
4566 struct propagate_block_info *pbi;
4569 rtx cond = NULL_RTX;
4574 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
4576 if (REG_NOTE_KIND (link) == REG_INC)
4577 mark_set_1 (pbi, SET, XEXP (link, 0),
4578 (GET_CODE (x) == COND_EXEC
4579 ? COND_EXEC_TEST (x) : NULL_RTX),
4583 switch (code = GET_CODE (x))
4587 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
4591 cond = COND_EXEC_TEST (x);
4592 x = COND_EXEC_CODE (x);
4598 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
4600 rtx sub = XVECEXP (x, 0, i);
4601 switch (code = GET_CODE (sub))
4604 if (cond != NULL_RTX)
4607 cond = COND_EXEC_TEST (sub);
4608 sub = COND_EXEC_CODE (sub);
4609 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
4615 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
4630 /* Process a single set, which appears in INSN. REG (which may not
4631 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
4632 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
4633 If the set is conditional (because it appear in a COND_EXEC), COND
4634 will be the condition. */
4637 mark_set_1 (pbi, code, reg, cond, insn, flags)
4638 struct propagate_block_info *pbi;
4640 rtx reg, cond, insn;
4643 int regno_first = -1, regno_last = -1;
4644 unsigned long not_dead = 0;
4647 /* Modifying just one hardware register of a multi-reg value or just a
4648 byte field of a register does not mean the value from before this insn
4649 is now dead. Of course, if it was dead after it's unused now. */
4651 switch (GET_CODE (reg))
4654 /* Some targets place small structures in registers for return values of
4655 functions. We have to detect this case specially here to get correct
4656 flow information. */
4657 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
4658 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
4659 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
4665 case STRICT_LOW_PART:
4666 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4668 reg = XEXP (reg, 0);
4669 while (GET_CODE (reg) == SUBREG
4670 || GET_CODE (reg) == ZERO_EXTRACT
4671 || GET_CODE (reg) == SIGN_EXTRACT
4672 || GET_CODE (reg) == STRICT_LOW_PART);
4673 if (GET_CODE (reg) == MEM)
4675 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
4679 regno_last = regno_first = REGNO (reg);
4680 if (regno_first < FIRST_PSEUDO_REGISTER)
4681 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
4685 if (GET_CODE (SUBREG_REG (reg)) == REG)
4687 enum machine_mode outer_mode = GET_MODE (reg);
4688 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
4690 /* Identify the range of registers affected. This is moderately
4691 tricky for hard registers. See alter_subreg. */
4693 regno_last = regno_first = REGNO (SUBREG_REG (reg));
4694 if (regno_first < FIRST_PSEUDO_REGISTER)
4696 regno_first += subreg_regno_offset (regno_first, inner_mode,
4699 regno_last = (regno_first
4700 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
4702 /* Since we've just adjusted the register number ranges, make
4703 sure REG matches. Otherwise some_was_live will be clear
4704 when it shouldn't have been, and we'll create incorrect
4705 REG_UNUSED notes. */
4706 reg = gen_rtx_REG (outer_mode, regno_first);
4710 /* If the number of words in the subreg is less than the number
4711 of words in the full register, we have a well-defined partial
4712 set. Otherwise the high bits are undefined.
4714 This is only really applicable to pseudos, since we just took
4715 care of multi-word hard registers. */
4716 if (((GET_MODE_SIZE (outer_mode)
4717 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
4718 < ((GET_MODE_SIZE (inner_mode)
4719 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
4720 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
4723 reg = SUBREG_REG (reg);
4727 reg = SUBREG_REG (reg);
4734 /* If this set is a MEM, then it kills any aliased writes.
4735 If this set is a REG, then it kills any MEMs which use the reg. */
4736 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4738 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
4739 invalidate_mems_from_set (pbi, reg);
4741 /* If the memory reference had embedded side effects (autoincrement
4742 address modes. Then we may need to kill some entries on the
4744 if (insn && GET_CODE (reg) == MEM)
4745 invalidate_mems_from_autoinc (pbi, insn);
4747 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
4748 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
4749 /* ??? With more effort we could track conditional memory life. */
4751 /* We do not know the size of a BLKmode store, so we do not track
4752 them for redundant store elimination. */
4753 && GET_MODE (reg) != BLKmode
4754 /* There are no REG_INC notes for SP, so we can't assume we'll see
4755 everything that invalidates it. To be safe, don't eliminate any
4756 stores though SP; none of them should be redundant anyway. */
4757 && ! reg_mentioned_p (stack_pointer_rtx, reg))
4760 /* Store a copy of mem, otherwise the address may be
4761 scrogged by find_auto_inc. */
4762 if (flags & PROP_AUTOINC)
4763 reg = shallow_copy_rtx (reg);
4765 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
4766 pbi->mem_set_list_len++;
4770 if (GET_CODE (reg) == REG
4771 && ! (regno_first == FRAME_POINTER_REGNUM
4772 && (! reload_completed || frame_pointer_needed))
4773 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4774 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
4775 && (! reload_completed || frame_pointer_needed))
4777 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4778 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
4782 int some_was_live = 0, some_was_dead = 0;
4784 for (i = regno_first; i <= regno_last; ++i)
4786 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
4789 /* Order of the set operation matters here since both
4790 sets may be the same. */
4791 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
4792 if (cond != NULL_RTX
4793 && ! REGNO_REG_SET_P (pbi->local_set, i))
4794 SET_REGNO_REG_SET (pbi->cond_local_set, i);
4796 SET_REGNO_REG_SET (pbi->local_set, i);
4798 if (code != CLOBBER)
4799 SET_REGNO_REG_SET (pbi->new_set, i);
4801 some_was_live |= needed_regno;
4802 some_was_dead |= ! needed_regno;
4805 #ifdef HAVE_conditional_execution
4806 /* Consider conditional death in deciding that the register needs
4808 if (some_was_live && ! not_dead
4809 /* The stack pointer is never dead. Well, not strictly true,
4810 but it's very difficult to tell from here. Hopefully
4811 combine_stack_adjustments will fix up the most egregious
4813 && regno_first != STACK_POINTER_REGNUM)
4815 for (i = regno_first; i <= regno_last; ++i)
4816 if (! mark_regno_cond_dead (pbi, i, cond))
4817 not_dead |= ((unsigned long) 1) << (i - regno_first);
4821 /* Additional data to record if this is the final pass. */
4822 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
4823 | PROP_DEATH_NOTES | PROP_AUTOINC))
4826 register int blocknum = pbi->bb->index;
4829 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4831 y = pbi->reg_next_use[regno_first];
4833 /* The next use is no longer next, since a store intervenes. */
4834 for (i = regno_first; i <= regno_last; ++i)
4835 pbi->reg_next_use[i] = 0;
4838 if (flags & PROP_REG_INFO)
4840 for (i = regno_first; i <= regno_last; ++i)
4842 /* Count (weighted) references, stores, etc. This counts a
4843 register twice if it is modified, but that is correct. */
4844 REG_N_SETS (i) += 1;
4845 REG_N_REFS (i) += (optimize_size ? 1
4846 : pbi->bb->loop_depth + 1);
4848 /* The insns where a reg is live are normally counted
4849 elsewhere, but we want the count to include the insn
4850 where the reg is set, and the normal counting mechanism
4851 would not count it. */
4852 REG_LIVE_LENGTH (i) += 1;
4855 /* If this is a hard reg, record this function uses the reg. */
4856 if (regno_first < FIRST_PSEUDO_REGISTER)
4858 for (i = regno_first; i <= regno_last; i++)
4859 regs_ever_live[i] = 1;
4863 /* Keep track of which basic blocks each reg appears in. */
4864 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
4865 REG_BASIC_BLOCK (regno_first) = blocknum;
4866 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
4867 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
4871 if (! some_was_dead)
4873 if (flags & PROP_LOG_LINKS)
4875 /* Make a logical link from the next following insn
4876 that uses this register, back to this insn.
4877 The following insns have already been processed.
4879 We don't build a LOG_LINK for hard registers containing
4880 in ASM_OPERANDs. If these registers get replaced,
4881 we might wind up changing the semantics of the insn,
4882 even if reload can make what appear to be valid
4883 assignments later. */
4884 if (y && (BLOCK_NUM (y) == blocknum)
4885 && (regno_first >= FIRST_PSEUDO_REGISTER
4886 || asm_noperands (PATTERN (y)) < 0))
4887 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4892 else if (! some_was_live)
4894 if (flags & PROP_REG_INFO)
4895 REG_N_DEATHS (regno_first) += 1;
4897 if (flags & PROP_DEATH_NOTES)
4899 /* Note that dead stores have already been deleted
4900 when possible. If we get here, we have found a
4901 dead store that cannot be eliminated (because the
4902 same insn does something useful). Indicate this
4903 by marking the reg being set as dying here. */
4905 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4910 if (flags & PROP_DEATH_NOTES)
4912 /* This is a case where we have a multi-word hard register
4913 and some, but not all, of the words of the register are
4914 needed in subsequent insns. Write REG_UNUSED notes
4915 for those parts that were not needed. This case should
4918 for (i = regno_first; i <= regno_last; ++i)
4919 if (! REGNO_REG_SET_P (pbi->reg_live, i))
4921 = alloc_EXPR_LIST (REG_UNUSED,
4922 gen_rtx_REG (reg_raw_mode[i], i),
4928 /* Mark the register as being dead. */
4930 /* The stack pointer is never dead. Well, not strictly true,
4931 but it's very difficult to tell from here. Hopefully
4932 combine_stack_adjustments will fix up the most egregious
4934 && regno_first != STACK_POINTER_REGNUM)
4936 for (i = regno_first; i <= regno_last; ++i)
4937 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
4938 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
4941 else if (GET_CODE (reg) == REG)
4943 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4944 pbi->reg_next_use[regno_first] = 0;
4947 /* If this is the last pass and this is a SCRATCH, show it will be dying
4948 here and count it. */
4949 else if (GET_CODE (reg) == SCRATCH)
4951 if (flags & PROP_DEATH_NOTES)
4953 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4957 #ifdef HAVE_conditional_execution
4958 /* Mark REGNO conditionally dead.
4959 Return true if the register is now unconditionally dead. */
4962 mark_regno_cond_dead (pbi, regno, cond)
4963 struct propagate_block_info *pbi;
4967 /* If this is a store to a predicate register, the value of the
4968 predicate is changing, we don't know that the predicate as seen
4969 before is the same as that seen after. Flush all dependent
4970 conditions from reg_cond_dead. This will make all such
4971 conditionally live registers unconditionally live. */
4972 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
4973 flush_reg_cond_reg (pbi, regno);
4975 /* If this is an unconditional store, remove any conditional
4976 life that may have existed. */
4977 if (cond == NULL_RTX)
4978 splay_tree_remove (pbi->reg_cond_dead, regno);
4981 splay_tree_node node;
4982 struct reg_cond_life_info *rcli;
4985 /* Otherwise this is a conditional set. Record that fact.
4986 It may have been conditionally used, or there may be a
4987 subsequent set with a complimentary condition. */
4989 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
4992 /* The register was unconditionally live previously.
4993 Record the current condition as the condition under
4994 which it is dead. */
4995 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4996 rcli->condition = cond;
4997 rcli->stores = cond;
4998 rcli->orig_condition = const0_rtx;
4999 splay_tree_insert (pbi->reg_cond_dead, regno,
5000 (splay_tree_value) rcli);
5002 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5004 /* Not unconditionaly dead. */
5009 /* The register was conditionally live previously.
5010 Add the new condition to the old. */
5011 rcli = (struct reg_cond_life_info *) node->value;
5012 ncond = rcli->condition;
5013 ncond = ior_reg_cond (ncond, cond, 1);
5014 if (rcli->stores == const0_rtx)
5015 rcli->stores = cond;
5016 else if (rcli->stores != const1_rtx)
5017 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
5019 /* If the register is now unconditionally dead, remove the entry
5020 in the splay_tree. A register is unconditionally dead if the
5021 dead condition ncond is true. A register is also unconditionally
5022 dead if the sum of all conditional stores is an unconditional
5023 store (stores is true), and the dead condition is identically the
5024 same as the original dead condition initialized at the end of
5025 the block. This is a pointer compare, not an rtx_equal_p
5027 if (ncond == const1_rtx
5028 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
5029 splay_tree_remove (pbi->reg_cond_dead, regno);
5032 rcli->condition = ncond;
5034 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5036 /* Not unconditionaly dead. */
5045 /* Called from splay_tree_delete for pbi->reg_cond_life. */
5048 free_reg_cond_life_info (value)
5049 splay_tree_value value;
5051 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
5055 /* Helper function for flush_reg_cond_reg. */
5058 flush_reg_cond_reg_1 (node, data)
5059 splay_tree_node node;
5062 struct reg_cond_life_info *rcli;
5063 int *xdata = (int *) data;
5064 unsigned int regno = xdata[0];
5066 /* Don't need to search if last flushed value was farther on in
5067 the in-order traversal. */
5068 if (xdata[1] >= (int) node->key)
5071 /* Splice out portions of the expression that refer to regno. */
5072 rcli = (struct reg_cond_life_info *) node->value;
5073 rcli->condition = elim_reg_cond (rcli->condition, regno);
5074 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
5075 rcli->stores = elim_reg_cond (rcli->stores, regno);
5077 /* If the entire condition is now false, signal the node to be removed. */
5078 if (rcli->condition == const0_rtx)
5080 xdata[1] = node->key;
5083 else if (rcli->condition == const1_rtx)
5089 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
5092 flush_reg_cond_reg (pbi, regno)
5093 struct propagate_block_info *pbi;
5100 while (splay_tree_foreach (pbi->reg_cond_dead,
5101 flush_reg_cond_reg_1, pair) == -1)
5102 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
5104 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
5107 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
5108 For ior/and, the ADD flag determines whether we want to add the new
5109 condition X to the old one unconditionally. If it is zero, we will
5110 only return a new expression if X allows us to simplify part of
5111 OLD, otherwise we return OLD unchanged to the caller.
5112 If ADD is nonzero, we will return a new condition in all cases. The
5113 toplevel caller of one of these functions should always pass 1 for
5117 ior_reg_cond (old, x, add)
5123 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5125 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5126 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
5127 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5129 if (GET_CODE (x) == GET_CODE (old)
5130 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5134 return gen_rtx_IOR (0, old, x);
5137 switch (GET_CODE (old))
5140 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5141 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5142 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5144 if (op0 == const0_rtx)
5146 if (op1 == const0_rtx)
5148 if (op0 == const1_rtx || op1 == const1_rtx)
5150 if (op0 == XEXP (old, 0))
5151 op0 = gen_rtx_IOR (0, op0, x);
5153 op1 = gen_rtx_IOR (0, op1, x);
5154 return gen_rtx_IOR (0, op0, op1);
5158 return gen_rtx_IOR (0, old, x);
5161 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5162 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5163 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5165 if (op0 == const1_rtx)
5167 if (op1 == const1_rtx)
5169 if (op0 == const0_rtx || op1 == const0_rtx)
5171 if (op0 == XEXP (old, 0))
5172 op0 = gen_rtx_IOR (0, op0, x);
5174 op1 = gen_rtx_IOR (0, op1, x);
5175 return gen_rtx_AND (0, op0, op1);
5179 return gen_rtx_IOR (0, old, x);
5182 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5183 if (op0 != XEXP (old, 0))
5184 return not_reg_cond (op0);
5187 return gen_rtx_IOR (0, old, x);
5198 enum rtx_code x_code;
5200 if (x == const0_rtx)
5202 else if (x == const1_rtx)
5204 x_code = GET_CODE (x);
5207 if (GET_RTX_CLASS (x_code) == '<'
5208 && GET_CODE (XEXP (x, 0)) == REG)
5210 if (XEXP (x, 1) != const0_rtx)
5213 return gen_rtx_fmt_ee (reverse_condition (x_code),
5214 VOIDmode, XEXP (x, 0), const0_rtx);
5216 return gen_rtx_NOT (0, x);
5220 and_reg_cond (old, x, add)
5226 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5228 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5229 && GET_CODE (x) == reverse_condition (GET_CODE (old))
5230 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5232 if (GET_CODE (x) == GET_CODE (old)
5233 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5237 return gen_rtx_AND (0, old, x);
5240 switch (GET_CODE (old))
5243 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5244 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5245 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5247 if (op0 == const0_rtx)
5249 if (op1 == const0_rtx)
5251 if (op0 == const1_rtx || op1 == const1_rtx)
5253 if (op0 == XEXP (old, 0))
5254 op0 = gen_rtx_AND (0, op0, x);
5256 op1 = gen_rtx_AND (0, op1, x);
5257 return gen_rtx_IOR (0, op0, op1);
5261 return gen_rtx_AND (0, old, x);
5264 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5265 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5266 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5268 if (op0 == const1_rtx)
5270 if (op1 == const1_rtx)
5272 if (op0 == const0_rtx || op1 == const0_rtx)
5274 if (op0 == XEXP (old, 0))
5275 op0 = gen_rtx_AND (0, op0, x);
5277 op1 = gen_rtx_AND (0, op1, x);
5278 return gen_rtx_AND (0, op0, op1);
5283 /* If X is identical to one of the existing terms of the AND,
5284 then just return what we already have. */
5285 /* ??? There really should be some sort of recursive check here in
5286 case there are nested ANDs. */
5287 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
5288 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
5289 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
5290 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
5293 return gen_rtx_AND (0, old, x);
5296 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5297 if (op0 != XEXP (old, 0))
5298 return not_reg_cond (op0);
5301 return gen_rtx_AND (0, old, x);
5308 /* Given a condition X, remove references to reg REGNO and return the
5309 new condition. The removal will be done so that all conditions
5310 involving REGNO are considered to evaluate to false. This function
5311 is used when the value of REGNO changes. */
5314 elim_reg_cond (x, regno)
5320 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
5322 if (REGNO (XEXP (x, 0)) == regno)
5327 switch (GET_CODE (x))
5330 op0 = elim_reg_cond (XEXP (x, 0), regno);
5331 op1 = elim_reg_cond (XEXP (x, 1), regno);
5332 if (op0 == const0_rtx || op1 == const0_rtx)
5334 if (op0 == const1_rtx)
5336 if (op1 == const1_rtx)
5338 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5340 return gen_rtx_AND (0, op0, op1);
5343 op0 = elim_reg_cond (XEXP (x, 0), regno);
5344 op1 = elim_reg_cond (XEXP (x, 1), regno);
5345 if (op0 == const1_rtx || op1 == const1_rtx)
5347 if (op0 == const0_rtx)
5349 if (op1 == const0_rtx)
5351 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5353 return gen_rtx_IOR (0, op0, op1);
5356 op0 = elim_reg_cond (XEXP (x, 0), regno);
5357 if (op0 == const0_rtx)
5359 if (op0 == const1_rtx)
5361 if (op0 != XEXP (x, 0))
5362 return not_reg_cond (op0);
5369 #endif /* HAVE_conditional_execution */
5373 /* Try to substitute the auto-inc expression INC as the address inside
5374 MEM which occurs in INSN. Currently, the address of MEM is an expression
5375 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
5376 that has a single set whose source is a PLUS of INCR_REG and something
5380 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
5381 struct propagate_block_info *pbi;
5382 rtx inc, insn, mem, incr, incr_reg;
5384 int regno = REGNO (incr_reg);
5385 rtx set = single_set (incr);
5386 rtx q = SET_DEST (set);
5387 rtx y = SET_SRC (set);
5388 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
5390 /* Make sure this reg appears only once in this insn. */
5391 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
5394 if (dead_or_set_p (incr, incr_reg)
5395 /* Mustn't autoinc an eliminable register. */
5396 && (regno >= FIRST_PSEUDO_REGISTER
5397 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
5399 /* This is the simple case. Try to make the auto-inc. If
5400 we can't, we are done. Otherwise, we will do any
5401 needed updates below. */
5402 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
5405 else if (GET_CODE (q) == REG
5406 /* PREV_INSN used here to check the semi-open interval
5408 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5409 /* We must also check for sets of q as q may be
5410 a call clobbered hard register and there may
5411 be a call between PREV_INSN (insn) and incr. */
5412 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5414 /* We have *p followed sometime later by q = p+size.
5415 Both p and q must be live afterward,
5416 and q is not used between INSN and its assignment.
5417 Change it to q = p, ...*q..., q = q+size.
5418 Then fall into the usual case. */
5422 emit_move_insn (q, incr_reg);
5423 insns = get_insns ();
5426 if (basic_block_for_insn)
5427 for (temp = insns; temp; temp = NEXT_INSN (temp))
5428 set_block_for_insn (temp, pbi->bb);
5430 /* If we can't make the auto-inc, or can't make the
5431 replacement into Y, exit. There's no point in making
5432 the change below if we can't do the auto-inc and doing
5433 so is not correct in the pre-inc case. */
5436 validate_change (insn, &XEXP (mem, 0), inc, 1);
5437 validate_change (incr, &XEXP (y, opnum), q, 1);
5438 if (! apply_change_group ())
5441 /* We now know we'll be doing this change, so emit the
5442 new insn(s) and do the updates. */
5443 emit_insns_before (insns, insn);
5445 if (pbi->bb->head == insn)
5446 pbi->bb->head = insns;
5448 /* INCR will become a NOTE and INSN won't contain a
5449 use of INCR_REG. If a use of INCR_REG was just placed in
5450 the insn before INSN, make that the next use.
5451 Otherwise, invalidate it. */
5452 if (GET_CODE (PREV_INSN (insn)) == INSN
5453 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
5454 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
5455 pbi->reg_next_use[regno] = PREV_INSN (insn);
5457 pbi->reg_next_use[regno] = 0;
5462 /* REGNO is now used in INCR which is below INSN, but
5463 it previously wasn't live here. If we don't mark
5464 it as live, we'll put a REG_DEAD note for it
5465 on this insn, which is incorrect. */
5466 SET_REGNO_REG_SET (pbi->reg_live, regno);
5468 /* If there are any calls between INSN and INCR, show
5469 that REGNO now crosses them. */
5470 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
5471 if (GET_CODE (temp) == CALL_INSN)
5472 REG_N_CALLS_CROSSED (regno)++;
5477 /* If we haven't returned, it means we were able to make the
5478 auto-inc, so update the status. First, record that this insn
5479 has an implicit side effect. */
5481 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
5483 /* Modify the old increment-insn to simply copy
5484 the already-incremented value of our register. */
5485 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
5488 /* If that makes it a no-op (copying the register into itself) delete
5489 it so it won't appear to be a "use" and a "set" of this
5491 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
5493 /* If the original source was dead, it's dead now. */
5496 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
5498 remove_note (incr, note);
5499 if (XEXP (note, 0) != incr_reg)
5500 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
5503 PUT_CODE (incr, NOTE);
5504 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
5505 NOTE_SOURCE_FILE (incr) = 0;
5508 if (regno >= FIRST_PSEUDO_REGISTER)
5510 /* Count an extra reference to the reg. When a reg is
5511 incremented, spilling it is worse, so we want to make
5512 that less likely. */
5513 REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5515 /* Count the increment as a setting of the register,
5516 even though it isn't a SET in rtl. */
5517 REG_N_SETS (regno)++;
5521 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
5525 find_auto_inc (pbi, x, insn)
5526 struct propagate_block_info *pbi;
5530 rtx addr = XEXP (x, 0);
5531 HOST_WIDE_INT offset = 0;
5532 rtx set, y, incr, inc_val;
5534 int size = GET_MODE_SIZE (GET_MODE (x));
5536 if (GET_CODE (insn) == JUMP_INSN)
5539 /* Here we detect use of an index register which might be good for
5540 postincrement, postdecrement, preincrement, or predecrement. */
5542 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
5543 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
5545 if (GET_CODE (addr) != REG)
5548 regno = REGNO (addr);
5550 /* Is the next use an increment that might make auto-increment? */
5551 incr = pbi->reg_next_use[regno];
5552 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
5554 set = single_set (incr);
5555 if (set == 0 || GET_CODE (set) != SET)
5559 if (GET_CODE (y) != PLUS)
5562 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
5563 inc_val = XEXP (y, 1);
5564 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
5565 inc_val = XEXP (y, 0);
5569 if (GET_CODE (inc_val) == CONST_INT)
5571 if (HAVE_POST_INCREMENT
5572 && (INTVAL (inc_val) == size && offset == 0))
5573 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
5575 else if (HAVE_POST_DECREMENT
5576 && (INTVAL (inc_val) == -size && offset == 0))
5577 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
5579 else if (HAVE_PRE_INCREMENT
5580 && (INTVAL (inc_val) == size && offset == size))
5581 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
5583 else if (HAVE_PRE_DECREMENT
5584 && (INTVAL (inc_val) == -size && offset == -size))
5585 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
5587 else if (HAVE_POST_MODIFY_DISP && offset == 0)
5588 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5589 gen_rtx_PLUS (Pmode,
5592 insn, x, incr, addr);
5594 else if (GET_CODE (inc_val) == REG
5595 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
5599 if (HAVE_POST_MODIFY_REG && offset == 0)
5600 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5601 gen_rtx_PLUS (Pmode,
5604 insn, x, incr, addr);
5608 #endif /* AUTO_INC_DEC */
5611 mark_used_reg (pbi, reg, cond, insn)
5612 struct propagate_block_info *pbi;
5614 rtx cond ATTRIBUTE_UNUSED;
5617 unsigned int regno_first, regno_last, i;
5618 int some_was_live, some_was_dead, some_not_set;
5620 regno_last = regno_first = REGNO (reg);
5621 if (regno_first < FIRST_PSEUDO_REGISTER)
5622 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
5624 /* Find out if any of this register is live after this instruction. */
5625 some_was_live = some_was_dead = 0;
5626 for (i = regno_first; i <= regno_last; ++i)
5628 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
5629 some_was_live |= needed_regno;
5630 some_was_dead |= ! needed_regno;
5633 /* Find out if any of the register was set this insn. */
5635 for (i = regno_first; i <= regno_last; ++i)
5636 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
5638 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5640 /* Record where each reg is used, so when the reg is set we know
5641 the next insn that uses it. */
5642 pbi->reg_next_use[regno_first] = insn;
5645 if (pbi->flags & PROP_REG_INFO)
5647 if (regno_first < FIRST_PSEUDO_REGISTER)
5649 /* If this is a register we are going to try to eliminate,
5650 don't mark it live here. If we are successful in
5651 eliminating it, it need not be live unless it is used for
5652 pseudos, in which case it will have been set live when it
5653 was allocated to the pseudos. If the register will not
5654 be eliminated, reload will set it live at that point.
5656 Otherwise, record that this function uses this register. */
5657 /* ??? The PPC backend tries to "eliminate" on the pic
5658 register to itself. This should be fixed. In the mean
5659 time, hack around it. */
5661 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
5662 && (regno_first == FRAME_POINTER_REGNUM
5663 || regno_first == ARG_POINTER_REGNUM)))
5664 for (i = regno_first; i <= regno_last; ++i)
5665 regs_ever_live[i] = 1;
5669 /* Keep track of which basic block each reg appears in. */
5671 register int blocknum = pbi->bb->index;
5672 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
5673 REG_BASIC_BLOCK (regno_first) = blocknum;
5674 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
5675 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
5677 /* Count (weighted) number of uses of each reg. */
5678 REG_N_REFS (regno_first)
5679 += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5683 /* Record and count the insns in which a reg dies. If it is used in
5684 this insn and was dead below the insn then it dies in this insn.
5685 If it was set in this insn, we do not make a REG_DEAD note;
5686 likewise if we already made such a note. */
5687 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
5691 /* Check for the case where the register dying partially
5692 overlaps the register set by this insn. */
5693 if (regno_first != regno_last)
5694 for (i = regno_first; i <= regno_last; ++i)
5695 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
5697 /* If none of the words in X is needed, make a REG_DEAD note.
5698 Otherwise, we must make partial REG_DEAD notes. */
5699 if (! some_was_live)
5701 if ((pbi->flags & PROP_DEATH_NOTES)
5702 && ! find_regno_note (insn, REG_DEAD, regno_first))
5704 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
5706 if (pbi->flags & PROP_REG_INFO)
5707 REG_N_DEATHS (regno_first)++;
5711 /* Don't make a REG_DEAD note for a part of a register
5712 that is set in the insn. */
5713 for (i = regno_first; i <= regno_last; ++i)
5714 if (! REGNO_REG_SET_P (pbi->reg_live, i)
5715 && ! dead_or_set_regno_p (insn, i))
5717 = alloc_EXPR_LIST (REG_DEAD,
5718 gen_rtx_REG (reg_raw_mode[i], i),
5723 /* Mark the register as being live. */
5724 for (i = regno_first; i <= regno_last; ++i)
5726 SET_REGNO_REG_SET (pbi->reg_live, i);
5728 #ifdef HAVE_conditional_execution
5729 /* If this is a conditional use, record that fact. If it is later
5730 conditionally set, we'll know to kill the register. */
5731 if (cond != NULL_RTX)
5733 splay_tree_node node;
5734 struct reg_cond_life_info *rcli;
5739 node = splay_tree_lookup (pbi->reg_cond_dead, i);
5742 /* The register was unconditionally live previously.
5743 No need to do anything. */
5747 /* The register was conditionally live previously.
5748 Subtract the new life cond from the old death cond. */
5749 rcli = (struct reg_cond_life_info *) node->value;
5750 ncond = rcli->condition;
5751 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
5753 /* If the register is now unconditionally live,
5754 remove the entry in the splay_tree. */
5755 if (ncond == const0_rtx)
5756 splay_tree_remove (pbi->reg_cond_dead, i);
5759 rcli->condition = ncond;
5760 SET_REGNO_REG_SET (pbi->reg_cond_reg,
5761 REGNO (XEXP (cond, 0)));
5767 /* The register was not previously live at all. Record
5768 the condition under which it is still dead. */
5769 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5770 rcli->condition = not_reg_cond (cond);
5771 rcli->stores = const0_rtx;
5772 rcli->orig_condition = const0_rtx;
5773 splay_tree_insert (pbi->reg_cond_dead, i,
5774 (splay_tree_value) rcli);
5776 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5779 else if (some_was_live)
5781 /* The register may have been conditionally live previously, but
5782 is now unconditionally live. Remove it from the conditionally
5783 dead list, so that a conditional set won't cause us to think
5785 splay_tree_remove (pbi->reg_cond_dead, i);
5791 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5792 This is done assuming the registers needed from X are those that
5793 have 1-bits in PBI->REG_LIVE.
5795 INSN is the containing instruction. If INSN is dead, this function
5799 mark_used_regs (pbi, x, cond, insn)
5800 struct propagate_block_info *pbi;
5803 register RTX_CODE code;
5805 int flags = pbi->flags;
5808 code = GET_CODE (x);
5828 /* If we are clobbering a MEM, mark any registers inside the address
5830 if (GET_CODE (XEXP (x, 0)) == MEM)
5831 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
5835 /* Don't bother watching stores to mems if this is not the
5836 final pass. We'll not be deleting dead stores this round. */
5837 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5839 /* Invalidate the data for the last MEM stored, but only if MEM is
5840 something that can be stored into. */
5841 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
5842 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
5843 /* Needn't clear the memory set list. */
5847 rtx temp = pbi->mem_set_list;
5848 rtx prev = NULL_RTX;
5853 next = XEXP (temp, 1);
5854 if (anti_dependence (XEXP (temp, 0), x))
5856 /* Splice temp out of the list. */
5858 XEXP (prev, 1) = next;
5860 pbi->mem_set_list = next;
5861 free_EXPR_LIST_node (temp);
5862 pbi->mem_set_list_len--;
5870 /* If the memory reference had embedded side effects (autoincrement
5871 address modes. Then we may need to kill some entries on the
5874 invalidate_mems_from_autoinc (pbi, insn);
5878 if (flags & PROP_AUTOINC)
5879 find_auto_inc (pbi, x, insn);
5884 #ifdef CLASS_CANNOT_CHANGE_MODE
5885 if (GET_CODE (SUBREG_REG (x)) == REG
5886 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
5887 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
5888 GET_MODE (SUBREG_REG (x))))
5889 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
5892 /* While we're here, optimize this case. */
5894 if (GET_CODE (x) != REG)
5899 /* See a register other than being set => mark it as needed. */
5900 mark_used_reg (pbi, x, cond, insn);
5905 register rtx testreg = SET_DEST (x);
5908 /* If storing into MEM, don't show it as being used. But do
5909 show the address as being used. */
5910 if (GET_CODE (testreg) == MEM)
5913 if (flags & PROP_AUTOINC)
5914 find_auto_inc (pbi, testreg, insn);
5916 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
5917 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5921 /* Storing in STRICT_LOW_PART is like storing in a reg
5922 in that this SET might be dead, so ignore it in TESTREG.
5923 but in some other ways it is like using the reg.
5925 Storing in a SUBREG or a bit field is like storing the entire
5926 register in that if the register's value is not used
5927 then this SET is not needed. */
5928 while (GET_CODE (testreg) == STRICT_LOW_PART
5929 || GET_CODE (testreg) == ZERO_EXTRACT
5930 || GET_CODE (testreg) == SIGN_EXTRACT
5931 || GET_CODE (testreg) == SUBREG)
5933 #ifdef CLASS_CANNOT_CHANGE_MODE
5934 if (GET_CODE (testreg) == SUBREG
5935 && GET_CODE (SUBREG_REG (testreg)) == REG
5936 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
5937 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
5938 GET_MODE (testreg)))
5939 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
5942 /* Modifying a single register in an alternate mode
5943 does not use any of the old value. But these other
5944 ways of storing in a register do use the old value. */
5945 if (GET_CODE (testreg) == SUBREG
5946 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5951 testreg = XEXP (testreg, 0);
5954 /* If this is a store into a register or group of registers,
5955 recursively scan the value being stored. */
5957 if ((GET_CODE (testreg) == PARALLEL
5958 && GET_MODE (testreg) == BLKmode)
5959 || (GET_CODE (testreg) == REG
5960 && (regno = REGNO (testreg),
5961 ! (regno == FRAME_POINTER_REGNUM
5962 && (! reload_completed || frame_pointer_needed)))
5963 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5964 && ! (regno == HARD_FRAME_POINTER_REGNUM
5965 && (! reload_completed || frame_pointer_needed))
5967 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5968 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5973 mark_used_regs (pbi, SET_DEST (x), cond, insn);
5974 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5981 case UNSPEC_VOLATILE:
5985 /* Traditional and volatile asm instructions must be considered to use
5986 and clobber all hard registers, all pseudo-registers and all of
5987 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
5989 Consider for instance a volatile asm that changes the fpu rounding
5990 mode. An insn should not be moved across this even if it only uses
5991 pseudo-regs because it might give an incorrectly rounded result.
5993 ?!? Unfortunately, marking all hard registers as live causes massive
5994 problems for the register allocator and marking all pseudos as live
5995 creates mountains of uninitialized variable warnings.
5997 So for now, just clear the memory set list and mark any regs
5998 we can find in ASM_OPERANDS as used. */
5999 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
6001 free_EXPR_LIST_list (&pbi->mem_set_list);
6002 pbi->mem_set_list_len = 0;
6005 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
6006 We can not just fall through here since then we would be confused
6007 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
6008 traditional asms unlike their normal usage. */
6009 if (code == ASM_OPERANDS)
6013 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
6014 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
6020 if (cond != NULL_RTX)
6023 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
6025 cond = COND_EXEC_TEST (x);
6026 x = COND_EXEC_CODE (x);
6030 /* We _do_not_ want to scan operands of phi nodes. Operands of
6031 a phi function are evaluated only when control reaches this
6032 block along a particular edge. Therefore, regs that appear
6033 as arguments to phi should not be added to the global live at
6041 /* Recursively scan the operands of this expression. */
6044 register const char *fmt = GET_RTX_FORMAT (code);
6047 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6051 /* Tail recursive case: save a function call level. */
6057 mark_used_regs (pbi, XEXP (x, i), cond, insn);
6059 else if (fmt[i] == 'E')
6062 for (j = 0; j < XVECLEN (x, i); j++)
6063 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
6072 try_pre_increment_1 (pbi, insn)
6073 struct propagate_block_info *pbi;
6076 /* Find the next use of this reg. If in same basic block,
6077 make it do pre-increment or pre-decrement if appropriate. */
6078 rtx x = single_set (insn);
6079 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
6080 * INTVAL (XEXP (SET_SRC (x), 1)));
6081 int regno = REGNO (SET_DEST (x));
6082 rtx y = pbi->reg_next_use[regno];
6084 && SET_DEST (x) != stack_pointer_rtx
6085 && BLOCK_NUM (y) == BLOCK_NUM (insn)
6086 /* Don't do this if the reg dies, or gets set in y; a standard addressing
6087 mode would be better. */
6088 && ! dead_or_set_p (y, SET_DEST (x))
6089 && try_pre_increment (y, SET_DEST (x), amount))
6091 /* We have found a suitable auto-increment and already changed
6092 insn Y to do it. So flush this increment instruction. */
6093 propagate_block_delete_insn (pbi->bb, insn);
6095 /* Count a reference to this reg for the increment insn we are
6096 deleting. When a reg is incremented, spilling it is worse,
6097 so we want to make that less likely. */
6098 if (regno >= FIRST_PSEUDO_REGISTER)
6100 REG_N_REFS (regno) += (optimize_size ? 1
6101 : pbi->bb->loop_depth + 1);
6102 REG_N_SETS (regno)++;
6105 /* Flush any remembered memories depending on the value of
6106 the incremented register. */
6107 invalidate_mems_from_set (pbi, SET_DEST (x));
6114 /* Try to change INSN so that it does pre-increment or pre-decrement
6115 addressing on register REG in order to add AMOUNT to REG.
6116 AMOUNT is negative for pre-decrement.
6117 Returns 1 if the change could be made.
6118 This checks all about the validity of the result of modifying INSN. */
6121 try_pre_increment (insn, reg, amount)
6123 HOST_WIDE_INT amount;
6127 /* Nonzero if we can try to make a pre-increment or pre-decrement.
6128 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
6130 /* Nonzero if we can try to make a post-increment or post-decrement.
6131 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
6132 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
6133 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
6136 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
6139 /* From the sign of increment, see which possibilities are conceivable
6140 on this target machine. */
6141 if (HAVE_PRE_INCREMENT && amount > 0)
6143 if (HAVE_POST_INCREMENT && amount > 0)
6146 if (HAVE_PRE_DECREMENT && amount < 0)
6148 if (HAVE_POST_DECREMENT && amount < 0)
6151 if (! (pre_ok || post_ok))
6154 /* It is not safe to add a side effect to a jump insn
6155 because if the incremented register is spilled and must be reloaded
6156 there would be no way to store the incremented value back in memory. */
6158 if (GET_CODE (insn) == JUMP_INSN)
6163 use = find_use_as_address (PATTERN (insn), reg, 0);
6164 if (post_ok && (use == 0 || use == (rtx) 1))
6166 use = find_use_as_address (PATTERN (insn), reg, -amount);
6170 if (use == 0 || use == (rtx) 1)
6173 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
6176 /* See if this combination of instruction and addressing mode exists. */
6177 if (! validate_change (insn, &XEXP (use, 0),
6178 gen_rtx_fmt_e (amount > 0
6179 ? (do_post ? POST_INC : PRE_INC)
6180 : (do_post ? POST_DEC : PRE_DEC),
6184 /* Record that this insn now has an implicit side effect on X. */
6185 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
6189 #endif /* AUTO_INC_DEC */
6191 /* Find the place in the rtx X where REG is used as a memory address.
6192 Return the MEM rtx that so uses it.
6193 If PLUSCONST is nonzero, search instead for a memory address equivalent to
6194 (plus REG (const_int PLUSCONST)).
6196 If such an address does not appear, return 0.
6197 If REG appears more than once, or is used other than in such an address,
6201 find_use_as_address (x, reg, plusconst)
6204 HOST_WIDE_INT plusconst;
6206 enum rtx_code code = GET_CODE (x);
6207 const char *fmt = GET_RTX_FORMAT (code);
6209 register rtx value = 0;
6212 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
6215 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
6216 && XEXP (XEXP (x, 0), 0) == reg
6217 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6218 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
6221 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
6223 /* If REG occurs inside a MEM used in a bit-field reference,
6224 that is unacceptable. */
6225 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
6226 return (rtx) (HOST_WIDE_INT) 1;
6230 return (rtx) (HOST_WIDE_INT) 1;
6232 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6236 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
6240 return (rtx) (HOST_WIDE_INT) 1;
6242 else if (fmt[i] == 'E')
6245 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6247 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
6251 return (rtx) (HOST_WIDE_INT) 1;
6259 /* Write information about registers and basic blocks into FILE.
6260 This is part of making a debugging dump. */
6263 dump_regset (r, outf)
6270 fputs (" (nil)", outf);
6274 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
6276 fprintf (outf, " %d", i);
6277 if (i < FIRST_PSEUDO_REGISTER)
6278 fprintf (outf, " [%s]",
6283 /* Print a human-reaable representation of R on the standard error
6284 stream. This function is designed to be used from within the
6291 dump_regset (r, stderr);
6292 putc ('\n', stderr);
6296 dump_flow_info (file)
6300 static const char * const reg_class_names[] = REG_CLASS_NAMES;
6302 fprintf (file, "%d registers.\n", max_regno);
6303 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
6306 enum reg_class class, altclass;
6307 fprintf (file, "\nRegister %d used %d times across %d insns",
6308 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
6309 if (REG_BASIC_BLOCK (i) >= 0)
6310 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
6312 fprintf (file, "; set %d time%s", REG_N_SETS (i),
6313 (REG_N_SETS (i) == 1) ? "" : "s");
6314 if (REG_USERVAR_P (regno_reg_rtx[i]))
6315 fprintf (file, "; user var");
6316 if (REG_N_DEATHS (i) != 1)
6317 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
6318 if (REG_N_CALLS_CROSSED (i) == 1)
6319 fprintf (file, "; crosses 1 call");
6320 else if (REG_N_CALLS_CROSSED (i))
6321 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
6322 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
6323 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
6324 class = reg_preferred_class (i);
6325 altclass = reg_alternate_class (i);
6326 if (class != GENERAL_REGS || altclass != ALL_REGS)
6328 if (altclass == ALL_REGS || class == ALL_REGS)
6329 fprintf (file, "; pref %s", reg_class_names[(int) class]);
6330 else if (altclass == NO_REGS)
6331 fprintf (file, "; %s or none", reg_class_names[(int) class]);
6333 fprintf (file, "; pref %s, else %s",
6334 reg_class_names[(int) class],
6335 reg_class_names[(int) altclass]);
6337 if (REG_POINTER (regno_reg_rtx[i]))
6338 fprintf (file, "; pointer");
6339 fprintf (file, ".\n");
6342 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
6343 for (i = 0; i < n_basic_blocks; i++)
6345 register basic_block bb = BASIC_BLOCK (i);
6348 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
6349 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count);
6351 fprintf (file, "Predecessors: ");
6352 for (e = bb->pred; e; e = e->pred_next)
6353 dump_edge_info (file, e, 0);
6355 fprintf (file, "\nSuccessors: ");
6356 for (e = bb->succ; e; e = e->succ_next)
6357 dump_edge_info (file, e, 1);
6359 fprintf (file, "\nRegisters live at start:");
6360 dump_regset (bb->global_live_at_start, file);
6362 fprintf (file, "\nRegisters live at end:");
6363 dump_regset (bb->global_live_at_end, file);
6374 dump_flow_info (stderr);
6378 dump_edge_info (file, e, do_succ)
6383 basic_block side = (do_succ ? e->dest : e->src);
6385 if (side == ENTRY_BLOCK_PTR)
6386 fputs (" ENTRY", file);
6387 else if (side == EXIT_BLOCK_PTR)
6388 fputs (" EXIT", file);
6390 fprintf (file, " %d", side->index);
6393 fprintf (file, " count:%d", e->count);
6397 static const char * const bitnames[] = {
6398 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6401 int i, flags = e->flags;
6405 for (i = 0; flags; i++)
6406 if (flags & (1 << i))
6412 if (i < (int) ARRAY_SIZE (bitnames))
6413 fputs (bitnames[i], file);
6415 fprintf (file, "%d", i);
6422 /* Print out one basic block with live information at start and end. */
6433 fprintf (outf, ";; Basic block %d, loop depth %d, count %d",
6434 bb->index, bb->loop_depth, bb->count);
6437 fputs (";; Predecessors: ", outf);
6438 for (e = bb->pred; e; e = e->pred_next)
6439 dump_edge_info (outf, e, 0);
6442 fputs (";; Registers live at start:", outf);
6443 dump_regset (bb->global_live_at_start, outf);
6446 for (insn = bb->head, last = NEXT_INSN (bb->end);
6448 insn = NEXT_INSN (insn))
6449 print_rtl_single (outf, insn);
6451 fputs (";; Registers live at end:", outf);
6452 dump_regset (bb->global_live_at_end, outf);
6455 fputs (";; Successors: ", outf);
6456 for (e = bb->succ; e; e = e->succ_next)
6457 dump_edge_info (outf, e, 1);
6465 dump_bb (bb, stderr);
6472 dump_bb (BASIC_BLOCK (n), stderr);
6475 /* Like print_rtl, but also print out live information for the start of each
6479 print_rtl_with_bb (outf, rtx_first)
6483 register rtx tmp_rtx;
6486 fprintf (outf, "(nil)\n");
6490 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
6491 int max_uid = get_max_uid ();
6492 basic_block *start = (basic_block *)
6493 xcalloc (max_uid, sizeof (basic_block));
6494 basic_block *end = (basic_block *)
6495 xcalloc (max_uid, sizeof (basic_block));
6496 enum bb_state *in_bb_p = (enum bb_state *)
6497 xcalloc (max_uid, sizeof (enum bb_state));
6499 for (i = n_basic_blocks - 1; i >= 0; i--)
6501 basic_block bb = BASIC_BLOCK (i);
6504 start[INSN_UID (bb->head)] = bb;
6505 end[INSN_UID (bb->end)] = bb;
6506 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
6508 enum bb_state state = IN_MULTIPLE_BB;
6509 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
6511 in_bb_p[INSN_UID (x)] = state;
6518 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
6523 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
6525 fprintf (outf, ";; Start of basic block %d, registers live:",
6527 dump_regset (bb->global_live_at_start, outf);
6531 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
6532 && GET_CODE (tmp_rtx) != NOTE
6533 && GET_CODE (tmp_rtx) != BARRIER)
6534 fprintf (outf, ";; Insn is not within a basic block\n");
6535 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
6536 fprintf (outf, ";; Insn is in multiple basic blocks\n");
6538 did_output = print_rtl_single (outf, tmp_rtx);
6540 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
6542 fprintf (outf, ";; End of basic block %d, registers live:\n",
6544 dump_regset (bb->global_live_at_end, outf);
6557 if (current_function_epilogue_delay_list != 0)
6559 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
6560 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
6561 tmp_rtx = XEXP (tmp_rtx, 1))
6562 print_rtl_single (outf, XEXP (tmp_rtx, 0));
6566 /* Dump the rtl into the current debugging dump file, then abort. */
6569 print_rtl_and_abort_fcn (file, line, function)
6572 const char *function;
6576 print_rtl_with_bb (rtl_dump_file, get_insns ());
6577 fclose (rtl_dump_file);
6580 fancy_abort (file, line, function);
6583 /* Recompute register set/reference counts immediately prior to register
6586 This avoids problems with set/reference counts changing to/from values
6587 which have special meanings to the register allocators.
6589 Additionally, the reference counts are the primary component used by the
6590 register allocators to prioritize pseudos for allocation to hard regs.
6591 More accurate reference counts generally lead to better register allocation.
6593 F is the first insn to be scanned.
6595 LOOP_STEP denotes how much loop_depth should be incremented per
6596 loop nesting level in order to increase the ref count more for
6597 references in a loop.
6599 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6600 possibly other information which is used by the register allocators. */
6603 recompute_reg_usage (f, loop_step)
6604 rtx f ATTRIBUTE_UNUSED;
6605 int loop_step ATTRIBUTE_UNUSED;
6607 allocate_reg_life_data ();
6608 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
6611 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6612 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6613 of the number of registers that died. */
6616 count_or_remove_death_notes (blocks, kill)
6622 for (i = n_basic_blocks - 1; i >= 0; --i)
6627 if (blocks && ! TEST_BIT (blocks, i))
6630 bb = BASIC_BLOCK (i);
6632 for (insn = bb->head;; insn = NEXT_INSN (insn))
6636 rtx *pprev = ®_NOTES (insn);
6641 switch (REG_NOTE_KIND (link))
6644 if (GET_CODE (XEXP (link, 0)) == REG)
6646 rtx reg = XEXP (link, 0);
6649 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
6652 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
6660 rtx next = XEXP (link, 1);
6661 free_EXPR_LIST_node (link);
6662 *pprev = link = next;
6668 pprev = &XEXP (link, 1);
6675 if (insn == bb->end)
6684 /* Update insns block within BB. */
6687 update_bb_for_insn (bb)
6692 if (! basic_block_for_insn)
6695 for (insn = bb->head; ; insn = NEXT_INSN (insn))
6697 set_block_for_insn (insn, bb);
6699 if (insn == bb->end)
6705 /* Record INSN's block as BB. */
6708 set_block_for_insn (insn, bb)
6712 size_t uid = INSN_UID (insn);
6713 if (uid >= basic_block_for_insn->num_elements)
6717 /* Add one-eighth the size so we don't keep calling xrealloc. */
6718 new_size = uid + (uid + 7) / 8;
6720 VARRAY_GROW (basic_block_for_insn, new_size);
6722 VARRAY_BB (basic_block_for_insn, uid) = bb;
6725 /* When a new insn has been inserted into an existing block, it will
6726 sometimes emit more than a single insn. This routine will set the
6727 block number for the specified insn, and look backwards in the insn
6728 chain to see if there are any other uninitialized insns immediately
6729 previous to this one, and set the block number for them too. */
6732 set_block_for_new_insns (insn, bb)
6736 set_block_for_insn (insn, bb);
6738 /* Scan the previous instructions setting the block number until we find
6739 an instruction that has the block number set, or we find a note
6741 for (insn = PREV_INSN (insn); insn != NULL_RTX; insn = PREV_INSN (insn))
6743 if (GET_CODE (insn) == NOTE)
6745 if (INSN_UID (insn) >= basic_block_for_insn->num_elements
6746 || BLOCK_FOR_INSN (insn) == 0)
6747 set_block_for_insn (insn, bb);
6753 /* Verify the CFG consistency. This function check some CFG invariants and
6754 aborts when something is wrong. Hope that this function will help to
6755 convert many optimization passes to preserve CFG consistent.
6757 Currently it does following checks:
6759 - test head/end pointers
6760 - overlapping of basic blocks
6761 - edge list corectness
6762 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6763 - tails of basic blocks (ensure that boundary is necesary)
6764 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6765 and NOTE_INSN_BASIC_BLOCK
6766 - check that all insns are in the basic blocks
6767 (except the switch handling code, barriers and notes)
6768 - check that all returns are followed by barriers
6770 In future it can be extended check a lot of other stuff as well
6771 (reachability of basic blocks, life information, etc. etc.). */
6776 const int max_uid = get_max_uid ();
6777 const rtx rtx_first = get_insns ();
6778 rtx last_head = get_last_insn ();
6779 basic_block *bb_info;
6781 int i, last_bb_num_seen, num_bb_notes, err = 0;
6783 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
6785 for (i = n_basic_blocks - 1; i >= 0; i--)
6787 basic_block bb = BASIC_BLOCK (i);
6788 rtx head = bb->head;
6791 /* Verify the end of the basic block is in the INSN chain. */
6792 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
6797 error ("End insn %d for block %d not found in the insn stream.",
6798 INSN_UID (end), bb->index);
6802 /* Work backwards from the end to the head of the basic block
6803 to verify the head is in the RTL chain. */
6804 for (; x != NULL_RTX; x = PREV_INSN (x))
6806 /* While walking over the insn chain, verify insns appear
6807 in only one basic block and initialize the BB_INFO array
6808 used by other passes. */
6809 if (bb_info[INSN_UID (x)] != NULL)
6811 error ("Insn %d is in multiple basic blocks (%d and %d)",
6812 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
6815 bb_info[INSN_UID (x)] = bb;
6822 error ("Head insn %d for block %d not found in the insn stream.",
6823 INSN_UID (head), bb->index);
6830 /* Now check the basic blocks (boundaries etc.) */
6831 for (i = n_basic_blocks - 1; i >= 0; i--)
6833 basic_block bb = BASIC_BLOCK (i);
6834 /* Check corectness of edge lists */
6843 "verify_flow_info: Basic block %d succ edge is corrupted\n",
6845 fprintf (stderr, "Predecessor: ");
6846 dump_edge_info (stderr, e, 0);
6847 fprintf (stderr, "\nSuccessor: ");
6848 dump_edge_info (stderr, e, 1);
6852 if (e->dest != EXIT_BLOCK_PTR)
6854 edge e2 = e->dest->pred;
6855 while (e2 && e2 != e)
6859 error ("Basic block %i edge lists are corrupted", bb->index);
6871 error ("Basic block %d pred edge is corrupted", bb->index);
6872 fputs ("Predecessor: ", stderr);
6873 dump_edge_info (stderr, e, 0);
6874 fputs ("\nSuccessor: ", stderr);
6875 dump_edge_info (stderr, e, 1);
6876 fputc ('\n', stderr);
6879 if (e->src != ENTRY_BLOCK_PTR)
6881 edge e2 = e->src->succ;
6882 while (e2 && e2 != e)
6886 error ("Basic block %i edge lists are corrupted", bb->index);
6893 /* OK pointers are correct. Now check the header of basic
6894 block. It ought to contain optional CODE_LABEL followed
6895 by NOTE_BASIC_BLOCK. */
6897 if (GET_CODE (x) == CODE_LABEL)
6901 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6907 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
6909 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6916 /* Do checks for empty blocks here */
6923 if (NOTE_INSN_BASIC_BLOCK_P (x))
6925 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6926 INSN_UID (x), bb->index);
6933 if (GET_CODE (x) == JUMP_INSN
6934 || GET_CODE (x) == CODE_LABEL
6935 || GET_CODE (x) == BARRIER)
6937 error ("In basic block %d:", bb->index);
6938 fatal_insn ("Flow control insn inside a basic block", x);
6946 last_bb_num_seen = -1;
6951 if (NOTE_INSN_BASIC_BLOCK_P (x))
6953 basic_block bb = NOTE_BASIC_BLOCK (x);
6955 if (bb->index != last_bb_num_seen + 1)
6956 /* Basic blocks not numbered consecutively. */
6959 last_bb_num_seen = bb->index;
6962 if (!bb_info[INSN_UID (x)])
6964 switch (GET_CODE (x))
6971 /* An addr_vec is placed outside any block block. */
6973 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
6974 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
6975 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
6980 /* But in any case, non-deletable labels can appear anywhere. */
6984 fatal_insn ("Insn outside basic block", x);
6989 && GET_CODE (x) == JUMP_INSN
6990 && returnjump_p (x) && ! condjump_p (x)
6991 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
6992 fatal_insn ("Return not followed by barrier", x);
6997 if (num_bb_notes != n_basic_blocks)
6999 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
7000 num_bb_notes, n_basic_blocks);
7009 /* Functions to access an edge list with a vector representation.
7010 Enough data is kept such that given an index number, the
7011 pred and succ that edge represents can be determined, or
7012 given a pred and a succ, its index number can be returned.
7013 This allows algorithms which consume a lot of memory to
7014 represent the normally full matrix of edge (pred,succ) with a
7015 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
7016 wasted space in the client code due to sparse flow graphs. */
7018 /* This functions initializes the edge list. Basically the entire
7019 flowgraph is processed, and all edges are assigned a number,
7020 and the data structure is filled in. */
7025 struct edge_list *elist;
7031 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
7035 /* Determine the number of edges in the flow graph by counting successor
7036 edges on each basic block. */
7037 for (x = 0; x < n_basic_blocks; x++)
7039 basic_block bb = BASIC_BLOCK (x);
7041 for (e = bb->succ; e; e = e->succ_next)
7044 /* Don't forget successors of the entry block. */
7045 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7048 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
7049 elist->num_blocks = block_count;
7050 elist->num_edges = num_edges;
7051 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
7055 /* Follow successors of the entry block, and register these edges. */
7056 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7058 elist->index_to_edge[num_edges] = e;
7062 for (x = 0; x < n_basic_blocks; x++)
7064 basic_block bb = BASIC_BLOCK (x);
7066 /* Follow all successors of blocks, and register these edges. */
7067 for (e = bb->succ; e; e = e->succ_next)
7069 elist->index_to_edge[num_edges] = e;
7076 /* This function free's memory associated with an edge list. */
7079 free_edge_list (elist)
7080 struct edge_list *elist;
7084 free (elist->index_to_edge);
7089 /* This function provides debug output showing an edge list. */
7092 print_edge_list (f, elist)
7094 struct edge_list *elist;
7097 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
7098 elist->num_blocks - 2, elist->num_edges);
7100 for (x = 0; x < elist->num_edges; x++)
7102 fprintf (f, " %-4d - edge(", x);
7103 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
7104 fprintf (f, "entry,");
7106 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
7108 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
7109 fprintf (f, "exit)\n");
7111 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
7115 /* This function provides an internal consistency check of an edge list,
7116 verifying that all edges are present, and that there are no
7120 verify_edge_list (f, elist)
7122 struct edge_list *elist;
7124 int x, pred, succ, index;
7127 for (x = 0; x < n_basic_blocks; x++)
7129 basic_block bb = BASIC_BLOCK (x);
7131 for (e = bb->succ; e; e = e->succ_next)
7133 pred = e->src->index;
7134 succ = e->dest->index;
7135 index = EDGE_INDEX (elist, e->src, e->dest);
7136 if (index == EDGE_INDEX_NO_EDGE)
7138 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7141 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7142 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7143 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7144 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7145 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7146 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7149 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7151 pred = e->src->index;
7152 succ = e->dest->index;
7153 index = EDGE_INDEX (elist, e->src, e->dest);
7154 if (index == EDGE_INDEX_NO_EDGE)
7156 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7159 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7160 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7161 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7162 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7163 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7164 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7166 /* We've verified that all the edges are in the list, no lets make sure
7167 there are no spurious edges in the list. */
7169 for (pred = 0; pred < n_basic_blocks; pred++)
7170 for (succ = 0; succ < n_basic_blocks; succ++)
7172 basic_block p = BASIC_BLOCK (pred);
7173 basic_block s = BASIC_BLOCK (succ);
7177 for (e = p->succ; e; e = e->succ_next)
7183 for (e = s->pred; e; e = e->pred_next)
7189 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7190 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7191 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
7193 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7194 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7195 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
7196 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7197 BASIC_BLOCK (succ)));
7199 for (succ = 0; succ < n_basic_blocks; succ++)
7201 basic_block p = ENTRY_BLOCK_PTR;
7202 basic_block s = BASIC_BLOCK (succ);
7206 for (e = p->succ; e; e = e->succ_next)
7212 for (e = s->pred; e; e = e->pred_next)
7218 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7219 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7220 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
7222 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7223 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7224 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
7225 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
7226 BASIC_BLOCK (succ)));
7228 for (pred = 0; pred < n_basic_blocks; pred++)
7230 basic_block p = BASIC_BLOCK (pred);
7231 basic_block s = EXIT_BLOCK_PTR;
7235 for (e = p->succ; e; e = e->succ_next)
7241 for (e = s->pred; e; e = e->pred_next)
7247 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7248 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7249 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
7251 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7252 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7253 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7254 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7259 /* This routine will determine what, if any, edge there is between
7260 a specified predecessor and successor. */
7263 find_edge_index (edge_list, pred, succ)
7264 struct edge_list *edge_list;
7265 basic_block pred, succ;
7268 for (x = 0; x < NUM_EDGES (edge_list); x++)
7270 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7271 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7274 return (EDGE_INDEX_NO_EDGE);
7277 /* This function will remove an edge from the flow graph. */
7283 edge last_pred = NULL;
7284 edge last_succ = NULL;
7286 basic_block src, dest;
7289 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7295 last_succ->succ_next = e->succ_next;
7297 src->succ = e->succ_next;
7299 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7305 last_pred->pred_next = e->pred_next;
7307 dest->pred = e->pred_next;
7313 /* This routine will remove any fake successor edges for a basic block.
7314 When the edge is removed, it is also removed from whatever predecessor
7318 remove_fake_successors (bb)
7322 for (e = bb->succ; e;)
7326 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7331 /* This routine will remove all fake edges from the flow graph. If
7332 we remove all fake successors, it will automatically remove all
7333 fake predecessors. */
7336 remove_fake_edges ()
7340 for (x = 0; x < n_basic_blocks; x++)
7341 remove_fake_successors (BASIC_BLOCK (x));
7343 /* We've handled all successors except the entry block's. */
7344 remove_fake_successors (ENTRY_BLOCK_PTR);
7347 /* This function will add a fake edge between any block which has no
7348 successors, and the exit block. Some data flow equations require these
7352 add_noreturn_fake_exit_edges ()
7356 for (x = 0; x < n_basic_blocks; x++)
7357 if (BASIC_BLOCK (x)->succ == NULL)
7358 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7361 /* This function adds a fake edge between any infinite loops to the
7362 exit block. Some optimizations require a path from each node to
7365 See also Morgan, Figure 3.10, pp. 82-83.
7367 The current implementation is ugly, not attempting to minimize the
7368 number of inserted fake edges. To reduce the number of fake edges
7369 to insert, add fake edges from _innermost_ loops containing only
7370 nodes not reachable from the exit block. */
7373 connect_infinite_loops_to_exit ()
7375 basic_block unvisited_block;
7377 /* Perform depth-first search in the reverse graph to find nodes
7378 reachable from the exit block. */
7379 struct depth_first_search_dsS dfs_ds;
7381 flow_dfs_compute_reverse_init (&dfs_ds);
7382 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7384 /* Repeatedly add fake edges, updating the unreachable nodes. */
7387 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7388 if (!unvisited_block)
7390 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7391 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7394 flow_dfs_compute_reverse_finish (&dfs_ds);
7399 /* Redirect an edge's successor from one block to another. */
7402 redirect_edge_succ (e, new_succ)
7404 basic_block new_succ;
7408 /* Disconnect the edge from the old successor block. */
7409 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7411 *pe = (*pe)->pred_next;
7413 /* Reconnect the edge to the new successor block. */
7414 e->pred_next = new_succ->pred;
7419 /* Redirect an edge's predecessor from one block to another. */
7422 redirect_edge_pred (e, new_pred)
7424 basic_block new_pred;
7428 /* Disconnect the edge from the old predecessor block. */
7429 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7431 *pe = (*pe)->succ_next;
7433 /* Reconnect the edge to the new predecessor block. */
7434 e->succ_next = new_pred->succ;
7439 /* Dump the list of basic blocks in the bitmap NODES. */
7442 flow_nodes_print (str, nodes, file)
7444 const sbitmap nodes;
7452 fprintf (file, "%s { ", str);
7453 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
7454 fputs ("}\n", file);
7458 /* Dump the list of edges in the array EDGE_LIST. */
7461 flow_edge_list_print (str, edge_list, num_edges, file)
7463 const edge *edge_list;
7472 fprintf (file, "%s { ", str);
7473 for (i = 0; i < num_edges; i++)
7474 fprintf (file, "%d->%d ", edge_list[i]->src->index,
7475 edge_list[i]->dest->index);
7476 fputs ("}\n", file);
7480 /* Dump loop related CFG information. */
7483 flow_loops_cfg_dump (loops, file)
7484 const struct loops *loops;
7489 if (! loops->num || ! file || ! loops->cfg.dom)
7492 for (i = 0; i < n_basic_blocks; i++)
7496 fprintf (file, ";; %d succs { ", i);
7497 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
7498 fprintf (file, "%d ", succ->dest->index);
7499 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
7502 /* Dump the DFS node order. */
7503 if (loops->cfg.dfs_order)
7505 fputs (";; DFS order: ", file);
7506 for (i = 0; i < n_basic_blocks; i++)
7507 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
7510 /* Dump the reverse completion node order. */
7511 if (loops->cfg.rc_order)
7513 fputs (";; RC order: ", file);
7514 for (i = 0; i < n_basic_blocks; i++)
7515 fprintf (file, "%d ", loops->cfg.rc_order[i]);
7520 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7523 flow_loop_nested_p (outer, loop)
7527 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
7531 /* Dump the loop information specified by LOOP to the stream FILE
7532 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7534 flow_loop_dump (loop, file, loop_dump_aux, verbose)
7535 const struct loop *loop;
7537 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7540 if (! loop || ! loop->header)
7543 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
7544 loop->num, INSN_UID (loop->first->head),
7545 INSN_UID (loop->last->end),
7546 loop->shared ? " shared" : "",
7547 loop->invalid ? " invalid" : "");
7548 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
7549 loop->header->index, loop->latch->index,
7550 loop->pre_header ? loop->pre_header->index : -1,
7551 loop->first->index, loop->last->index);
7552 fprintf (file, ";; depth %d, level %d, outer %ld\n",
7553 loop->depth, loop->level,
7554 (long) (loop->outer ? loop->outer->num : -1));
7556 if (loop->pre_header_edges)
7557 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
7558 loop->num_pre_header_edges, file);
7559 flow_edge_list_print (";; entry edges", loop->entry_edges,
7560 loop->num_entries, file);
7561 fprintf (file, ";; %d", loop->num_nodes);
7562 flow_nodes_print (" nodes", loop->nodes, file);
7563 flow_edge_list_print (";; exit edges", loop->exit_edges,
7564 loop->num_exits, file);
7565 if (loop->exits_doms)
7566 flow_nodes_print (";; exit doms", loop->exits_doms, file);
7568 loop_dump_aux (loop, file, verbose);
7572 /* Dump the loop information specified by LOOPS to the stream FILE,
7573 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7575 flow_loops_dump (loops, file, loop_dump_aux, verbose)
7576 const struct loops *loops;
7578 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7584 num_loops = loops->num;
7585 if (! num_loops || ! file)
7588 fprintf (file, ";; %d loops found, %d levels\n",
7589 num_loops, loops->levels);
7591 for (i = 0; i < num_loops; i++)
7593 struct loop *loop = &loops->array[i];
7595 flow_loop_dump (loop, file, loop_dump_aux, verbose);
7601 for (j = 0; j < i; j++)
7603 struct loop *oloop = &loops->array[j];
7605 if (loop->header == oloop->header)
7610 smaller = loop->num_nodes < oloop->num_nodes;
7612 /* If the union of LOOP and OLOOP is different than
7613 the larger of LOOP and OLOOP then LOOP and OLOOP
7614 must be disjoint. */
7615 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
7616 smaller ? oloop : loop);
7618 ";; loop header %d shared by loops %d, %d %s\n",
7619 loop->header->index, i, j,
7620 disjoint ? "disjoint" : "nested");
7627 flow_loops_cfg_dump (loops, file);
7631 /* Free all the memory allocated for LOOPS. */
7634 flow_loops_free (loops)
7635 struct loops *loops;
7644 /* Free the loop descriptors. */
7645 for (i = 0; i < loops->num; i++)
7647 struct loop *loop = &loops->array[i];
7649 if (loop->pre_header_edges)
7650 free (loop->pre_header_edges);
7652 sbitmap_free (loop->nodes);
7653 if (loop->entry_edges)
7654 free (loop->entry_edges);
7655 if (loop->exit_edges)
7656 free (loop->exit_edges);
7657 if (loop->exits_doms)
7658 sbitmap_free (loop->exits_doms);
7660 free (loops->array);
7661 loops->array = NULL;
7664 sbitmap_vector_free (loops->cfg.dom);
7665 if (loops->cfg.dfs_order)
7666 free (loops->cfg.dfs_order);
7668 if (loops->shared_headers)
7669 sbitmap_free (loops->shared_headers);
7674 /* Find the entry edges into the loop with header HEADER and nodes
7675 NODES and store in ENTRY_EDGES array. Return the number of entry
7676 edges from the loop. */
7679 flow_loop_entry_edges_find (header, nodes, entry_edges)
7681 const sbitmap nodes;
7687 *entry_edges = NULL;
7690 for (e = header->pred; e; e = e->pred_next)
7692 basic_block src = e->src;
7694 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7701 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
7704 for (e = header->pred; e; e = e->pred_next)
7706 basic_block src = e->src;
7708 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7709 (*entry_edges)[num_entries++] = e;
7716 /* Find the exit edges from the loop using the bitmap of loop nodes
7717 NODES and store in EXIT_EDGES array. Return the number of
7718 exit edges from the loop. */
7721 flow_loop_exit_edges_find (nodes, exit_edges)
7722 const sbitmap nodes;
7731 /* Check all nodes within the loop to see if there are any
7732 successors not in the loop. Note that a node may have multiple
7733 exiting edges ????? A node can have one jumping edge and one fallthru
7734 edge so only one of these can exit the loop. */
7736 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7737 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7739 basic_block dest = e->dest;
7741 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7749 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
7751 /* Store all exiting edges into an array. */
7753 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7754 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7756 basic_block dest = e->dest;
7758 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7759 (*exit_edges)[num_exits++] = e;
7767 /* Find the nodes contained within the loop with header HEADER and
7768 latch LATCH and store in NODES. Return the number of nodes within
7772 flow_loop_nodes_find (header, latch, nodes)
7781 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
7784 /* Start with only the loop header in the set of loop nodes. */
7785 sbitmap_zero (nodes);
7786 SET_BIT (nodes, header->index);
7788 header->loop_depth++;
7790 /* Push the loop latch on to the stack. */
7791 if (! TEST_BIT (nodes, latch->index))
7793 SET_BIT (nodes, latch->index);
7794 latch->loop_depth++;
7796 stack[sp++] = latch;
7805 for (e = node->pred; e; e = e->pred_next)
7807 basic_block ancestor = e->src;
7809 /* If each ancestor not marked as part of loop, add to set of
7810 loop nodes and push on to stack. */
7811 if (ancestor != ENTRY_BLOCK_PTR
7812 && ! TEST_BIT (nodes, ancestor->index))
7814 SET_BIT (nodes, ancestor->index);
7815 ancestor->loop_depth++;
7817 stack[sp++] = ancestor;
7825 /* Compute the depth first search order and store in the array
7826 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7827 RC_ORDER is non-zero, return the reverse completion number for each
7828 node. Returns the number of nodes visited. A depth first search
7829 tries to get as far away from the starting point as quickly as
7833 flow_depth_first_order_compute (dfs_order, rc_order)
7840 int rcnum = n_basic_blocks - 1;
7843 /* Allocate stack for back-tracking up CFG. */
7844 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
7847 /* Allocate bitmap to track nodes that have been visited. */
7848 visited = sbitmap_alloc (n_basic_blocks);
7850 /* None of the nodes in the CFG have been visited yet. */
7851 sbitmap_zero (visited);
7853 /* Push the first edge on to the stack. */
7854 stack[sp++] = ENTRY_BLOCK_PTR->succ;
7862 /* Look at the edge on the top of the stack. */
7867 /* Check if the edge destination has been visited yet. */
7868 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
7870 /* Mark that we have visited the destination. */
7871 SET_BIT (visited, dest->index);
7874 dfs_order[dfsnum++] = dest->index;
7878 /* Since the DEST node has been visited for the first
7879 time, check its successors. */
7880 stack[sp++] = dest->succ;
7884 /* There are no successors for the DEST node so assign
7885 its reverse completion number. */
7887 rc_order[rcnum--] = dest->index;
7892 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
7894 /* There are no more successors for the SRC node
7895 so assign its reverse completion number. */
7897 rc_order[rcnum--] = src->index;
7901 stack[sp - 1] = e->succ_next;
7908 sbitmap_free (visited);
7910 /* The number of nodes visited should not be greater than
7912 if (dfsnum > n_basic_blocks)
7915 /* There are some nodes left in the CFG that are unreachable. */
7916 if (dfsnum < n_basic_blocks)
7921 /* Compute the depth first search order on the _reverse_ graph and
7922 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7923 Returns the number of nodes visited.
7925 The computation is split into three pieces:
7927 flow_dfs_compute_reverse_init () creates the necessary data
7930 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7931 structures. The block will start the search.
7933 flow_dfs_compute_reverse_execute () continues (or starts) the
7934 search using the block on the top of the stack, stopping when the
7937 flow_dfs_compute_reverse_finish () destroys the necessary data
7940 Thus, the user will probably call ..._init(), call ..._add_bb() to
7941 add a beginning basic block to the stack, call ..._execute(),
7942 possibly add another bb to the stack and again call ..._execute(),
7943 ..., and finally call _finish(). */
7945 /* Initialize the data structures used for depth-first search on the
7946 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7947 added to the basic block stack. DATA is the current depth-first
7948 search context. If INITIALIZE_STACK is non-zero, there is an
7949 element on the stack. */
7952 flow_dfs_compute_reverse_init (data)
7953 depth_first_search_ds data;
7955 /* Allocate stack for back-tracking up CFG. */
7957 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
7958 * sizeof (basic_block));
7961 /* Allocate bitmap to track nodes that have been visited. */
7962 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
7964 /* None of the nodes in the CFG have been visited yet. */
7965 sbitmap_zero (data->visited_blocks);
7970 /* Add the specified basic block to the top of the dfs data
7971 structures. When the search continues, it will start at the
7975 flow_dfs_compute_reverse_add_bb (data, bb)
7976 depth_first_search_ds data;
7979 data->stack[data->sp++] = bb;
7983 /* Continue the depth-first search through the reverse graph starting
7984 with the block at the stack's top and ending when the stack is
7985 empty. Visited nodes are marked. Returns an unvisited basic
7986 block, or NULL if there is none available. */
7989 flow_dfs_compute_reverse_execute (data)
7990 depth_first_search_ds data;
7996 while (data->sp > 0)
7998 bb = data->stack[--data->sp];
8000 /* Mark that we have visited this node. */
8001 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
8003 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
8005 /* Perform depth-first search on adjacent vertices. */
8006 for (e = bb->pred; e; e = e->pred_next)
8007 flow_dfs_compute_reverse_add_bb (data, e->src);
8011 /* Determine if there are unvisited basic blocks. */
8012 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
8013 if (!TEST_BIT (data->visited_blocks, i))
8014 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
8018 /* Destroy the data structures needed for depth-first search on the
8022 flow_dfs_compute_reverse_finish (data)
8023 depth_first_search_ds data;
8026 sbitmap_free (data->visited_blocks);
8031 /* Find the root node of the loop pre-header extended basic block and
8032 the edges along the trace from the root node to the loop header. */
8035 flow_loop_pre_header_scan (loop)
8041 loop->num_pre_header_edges = 0;
8043 if (loop->num_entries != 1)
8046 ebb = loop->entry_edges[0]->src;
8048 if (ebb != ENTRY_BLOCK_PTR)
8052 /* Count number of edges along trace from loop header to
8053 root of pre-header extended basic block. Usually this is
8054 only one or two edges. */
8056 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
8058 ebb = ebb->pred->src;
8062 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
8063 loop->num_pre_header_edges = num;
8065 /* Store edges in order that they are followed. The source
8066 of the first edge is the root node of the pre-header extended
8067 basic block and the destination of the last last edge is
8069 for (e = loop->entry_edges[0]; num; e = e->src->pred)
8071 loop->pre_header_edges[--num] = e;
8077 /* Return the block for the pre-header of the loop with header
8078 HEADER where DOM specifies the dominator information. Return NULL if
8079 there is no pre-header. */
8082 flow_loop_pre_header_find (header, dom)
8086 basic_block pre_header;
8089 /* If block p is a predecessor of the header and is the only block
8090 that the header does not dominate, then it is the pre-header. */
8092 for (e = header->pred; e; e = e->pred_next)
8094 basic_block node = e->src;
8096 if (node != ENTRY_BLOCK_PTR
8097 && ! TEST_BIT (dom[node->index], header->index))
8099 if (pre_header == NULL)
8103 /* There are multiple edges into the header from outside
8104 the loop so there is no pre-header block. */
8113 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
8114 previously added. The insertion algorithm assumes that the loops
8115 are added in the order found by a depth first search of the CFG. */
8118 flow_loop_tree_node_add (prevloop, loop)
8119 struct loop *prevloop;
8123 if (flow_loop_nested_p (prevloop, loop))
8125 prevloop->inner = loop;
8126 loop->outer = prevloop;
8130 while (prevloop->outer)
8132 if (flow_loop_nested_p (prevloop->outer, loop))
8134 prevloop->next = loop;
8135 loop->outer = prevloop->outer;
8138 prevloop = prevloop->outer;
8141 prevloop->next = loop;
8145 /* Build the loop hierarchy tree for LOOPS. */
8148 flow_loops_tree_build (loops)
8149 struct loops *loops;
8154 num_loops = loops->num;
8158 /* Root the loop hierarchy tree with the first loop found.
8159 Since we used a depth first search this should be the
8161 loops->tree = &loops->array[0];
8162 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
8164 /* Add the remaining loops to the tree. */
8165 for (i = 1; i < num_loops; i++)
8166 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
8169 /* Helper function to compute loop nesting depth and enclosed loop level
8170 for the natural loop specified by LOOP at the loop depth DEPTH.
8171 Returns the loop level. */
8174 flow_loop_level_compute (loop, depth)
8184 /* Traverse loop tree assigning depth and computing level as the
8185 maximum level of all the inner loops of this loop. The loop
8186 level is equivalent to the height of the loop in the loop tree
8187 and corresponds to the number of enclosed loop levels (including
8189 for (inner = loop->inner; inner; inner = inner->next)
8193 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
8198 loop->level = level;
8199 loop->depth = depth;
8203 /* Compute the loop nesting depth and enclosed loop level for the loop
8204 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
8208 flow_loops_level_compute (loops)
8209 struct loops *loops;
8215 /* Traverse all the outer level loops. */
8216 for (loop = loops->tree; loop; loop = loop->next)
8218 level = flow_loop_level_compute (loop, 1);
8226 /* Scan a single natural loop specified by LOOP collecting information
8227 about it specified by FLAGS. */
8230 flow_loop_scan (loops, loop, flags)
8231 struct loops *loops;
8235 /* Determine prerequisites. */
8236 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
8237 flags |= LOOP_EXIT_EDGES;
8239 if (flags & LOOP_ENTRY_EDGES)
8241 /* Find edges which enter the loop header.
8242 Note that the entry edges should only
8243 enter the header of a natural loop. */
8245 = flow_loop_entry_edges_find (loop->header,
8247 &loop->entry_edges);
8250 if (flags & LOOP_EXIT_EDGES)
8252 /* Find edges which exit the loop. */
8254 = flow_loop_exit_edges_find (loop->nodes,
8258 if (flags & LOOP_EXITS_DOMS)
8262 /* Determine which loop nodes dominate all the exits
8264 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8265 sbitmap_copy (loop->exits_doms, loop->nodes);
8266 for (j = 0; j < loop->num_exits; j++)
8267 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8268 loops->cfg.dom[loop->exit_edges[j]->src->index]);
8270 /* The header of a natural loop must dominate
8272 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8276 if (flags & LOOP_PRE_HEADER)
8278 /* Look to see if the loop has a pre-header node. */
8280 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
8282 /* Find the blocks within the extended basic block of
8283 the loop pre-header. */
8284 flow_loop_pre_header_scan (loop);
8290 /* Find all the natural loops in the function and save in LOOPS structure
8291 and recalculate loop_depth information in basic block structures.
8292 FLAGS controls which loop information is collected.
8293 Return the number of natural loops found. */
8296 flow_loops_find (loops, flags)
8297 struct loops *loops;
8309 /* This function cannot be repeatedly called with different
8310 flags to build up the loop information. The loop tree
8311 must always be built if this function is called. */
8312 if (! (flags & LOOP_TREE))
8315 memset (loops, 0, sizeof (*loops));
8317 /* Taking care of this degenerate case makes the rest of
8318 this code simpler. */
8319 if (n_basic_blocks == 0)
8325 /* Compute the dominators. */
8326 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8327 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
8329 /* Count the number of loop edges (back edges). This should be the
8330 same as the number of natural loops. */
8333 for (b = 0; b < n_basic_blocks; b++)
8337 header = BASIC_BLOCK (b);
8338 header->loop_depth = 0;
8340 for (e = header->pred; e; e = e->pred_next)
8342 basic_block latch = e->src;
8344 /* Look for back edges where a predecessor is dominated
8345 by this block. A natural loop has a single entry
8346 node (header) that dominates all the nodes in the
8347 loop. It also has single back edge to the header
8348 from a latch node. Note that multiple natural loops
8349 may share the same header. */
8350 if (b != header->index)
8353 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8360 /* Compute depth first search order of the CFG so that outer
8361 natural loops will be found before inner natural loops. */
8362 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8363 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8364 flow_depth_first_order_compute (dfs_order, rc_order);
8366 /* Save CFG derived information to avoid recomputing it. */
8367 loops->cfg.dom = dom;
8368 loops->cfg.dfs_order = dfs_order;
8369 loops->cfg.rc_order = rc_order;
8371 /* Allocate loop structures. */
8373 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8375 headers = sbitmap_alloc (n_basic_blocks);
8376 sbitmap_zero (headers);
8378 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8379 sbitmap_zero (loops->shared_headers);
8381 /* Find and record information about all the natural loops
8384 for (b = 0; b < n_basic_blocks; b++)
8388 /* Search the nodes of the CFG in reverse completion order
8389 so that we can find outer loops first. */
8390 header = BASIC_BLOCK (rc_order[b]);
8392 /* Look for all the possible latch blocks for this header. */
8393 for (e = header->pred; e; e = e->pred_next)
8395 basic_block latch = e->src;
8397 /* Look for back edges where a predecessor is dominated
8398 by this block. A natural loop has a single entry
8399 node (header) that dominates all the nodes in the
8400 loop. It also has single back edge to the header
8401 from a latch node. Note that multiple natural loops
8402 may share the same header. */
8403 if (latch != ENTRY_BLOCK_PTR
8404 && TEST_BIT (dom[latch->index], header->index))
8408 loop = loops->array + num_loops;
8410 loop->header = header;
8411 loop->latch = latch;
8412 loop->num = num_loops;
8419 for (i = 0; i < num_loops; i++)
8421 struct loop *loop = &loops->array[i];
8423 /* Keep track of blocks that are loop headers so
8424 that we can tell which loops should be merged. */
8425 if (TEST_BIT (headers, loop->header->index))
8426 SET_BIT (loops->shared_headers, loop->header->index);
8427 SET_BIT (headers, loop->header->index);
8429 /* Find nodes contained within the loop. */
8430 loop->nodes = sbitmap_alloc (n_basic_blocks);
8432 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8434 /* Compute first and last blocks within the loop.
8435 These are often the same as the loop header and
8436 loop latch respectively, but this is not always
8439 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
8441 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
8443 flow_loop_scan (loops, loop, flags);
8446 /* Natural loops with shared headers may either be disjoint or
8447 nested. Disjoint loops with shared headers cannot be inner
8448 loops and should be merged. For now just mark loops that share
8450 for (i = 0; i < num_loops; i++)
8451 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
8452 loops->array[i].shared = 1;
8454 sbitmap_free (headers);
8457 loops->num = num_loops;
8459 /* Build the loop hierarchy tree. */
8460 flow_loops_tree_build (loops);
8462 /* Assign the loop nesting depth and enclosed loop level for each
8464 loops->levels = flow_loops_level_compute (loops);
8470 /* Update the information regarding the loops in the CFG
8471 specified by LOOPS. */
8473 flow_loops_update (loops, flags)
8474 struct loops *loops;
8477 /* One day we may want to update the current loop data. For now
8478 throw away the old stuff and rebuild what we need. */
8480 flow_loops_free (loops);
8482 return flow_loops_find (loops, flags);
8486 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
8489 flow_loop_outside_edge_p (loop, e)
8490 const struct loop *loop;
8493 if (e->dest != loop->header)
8495 return (e->src == ENTRY_BLOCK_PTR)
8496 || ! TEST_BIT (loop->nodes, e->src->index);
8499 /* Clear LOG_LINKS fields of insns in a chain.
8500 Also clear the global_live_at_{start,end} fields of the basic block
8504 clear_log_links (insns)
8510 for (i = insns; i; i = NEXT_INSN (i))
8514 for (b = 0; b < n_basic_blocks; b++)
8516 basic_block bb = BASIC_BLOCK (b);
8518 bb->global_live_at_start = NULL;
8519 bb->global_live_at_end = NULL;
8522 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
8523 EXIT_BLOCK_PTR->global_live_at_start = NULL;
8526 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
8527 correspond to the hard registers, if any, set in that map. This
8528 could be done far more efficiently by having all sorts of special-cases
8529 with moving single words, but probably isn't worth the trouble. */
8532 reg_set_to_hard_reg_set (to, from)
8538 EXECUTE_IF_SET_IN_BITMAP
8541 if (i >= FIRST_PSEUDO_REGISTER)
8543 SET_HARD_REG_BIT (*to, i);
8547 /* Called once at intialization time. */
8552 static int initialized;
8556 gcc_obstack_init (&flow_obstack);
8557 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
8562 obstack_free (&flow_obstack, flow_firstobj);
8563 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);