1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000 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"
136 #include "insn-flags.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 /* The obstack on which the flow graph components are allocated. */
173 struct obstack flow_obstack;
174 static char *flow_firstobj;
176 /* Number of basic blocks in the current function. */
180 /* Number of edges in the current function. */
184 /* The basic block array. */
186 varray_type basic_block_info;
188 /* The special entry and exit blocks. */
190 struct basic_block_def entry_exit_blocks[2]
195 NULL, /* local_set */
196 NULL, /* cond_local_set */
197 NULL, /* global_live_at_start */
198 NULL, /* global_live_at_end */
200 ENTRY_BLOCK, /* index */
202 -1, -1, /* eh_beg, eh_end */
210 NULL, /* local_set */
211 NULL, /* cond_local_set */
212 NULL, /* global_live_at_start */
213 NULL, /* global_live_at_end */
215 EXIT_BLOCK, /* index */
217 -1, -1, /* eh_beg, eh_end */
222 /* Nonzero if the second flow pass has completed. */
225 /* Maximum register number used in this function, plus one. */
229 /* Indexed by n, giving various register information */
231 varray_type reg_n_info;
233 /* Size of a regset for the current function,
234 in (1) bytes and (2) elements. */
239 /* Regset of regs live when calls to `setjmp'-like functions happen. */
240 /* ??? Does this exist only for the setjmp-clobbered warning message? */
242 regset regs_live_at_setjmp;
244 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
245 that have to go in the same hard reg.
246 The first two regs in the list are a pair, and the next two
247 are another pair, etc. */
250 /* Set of registers that may be eliminable. These are handled specially
251 in updating regs_ever_live. */
253 static HARD_REG_SET elim_reg_set;
255 /* The basic block structure for every insn, indexed by uid. */
257 varray_type basic_block_for_insn;
259 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
260 /* ??? Should probably be using LABEL_NUSES instead. It would take a
261 bit of surgery to be able to use or co-opt the routines in jump. */
263 static rtx label_value_list;
264 static rtx tail_recursion_label_list;
266 /* Holds information for tracking conditional register life information. */
267 struct reg_cond_life_info
269 /* An EXPR_LIST of conditions under which a register is dead. */
272 /* ??? Could store mask of bytes that are dead, so that we could finally
273 track lifetimes of multi-word registers accessed via subregs. */
276 /* For use in communicating between propagate_block and its subroutines.
277 Holds all information needed to compute life and def-use information. */
279 struct propagate_block_info
281 /* The basic block we're considering. */
284 /* Bit N is set if register N is conditionally or unconditionally live. */
287 /* Bit N is set if register N is set this insn. */
290 /* Element N is the next insn that uses (hard or pseudo) register N
291 within the current basic block; or zero, if there is no such insn. */
294 /* Contains a list of all the MEMs we are tracking for dead store
298 /* If non-null, record the set of registers set unconditionally in the
302 /* If non-null, record the set of registers set conditionally in the
304 regset cond_local_set;
306 #ifdef HAVE_conditional_execution
307 /* Indexed by register number, holds a reg_cond_life_info for each
308 register that is not unconditionally live or dead. */
309 splay_tree reg_cond_dead;
311 /* Bit N is set if register N is in an expression in reg_cond_dead. */
315 /* Non-zero if the value of CC0 is live. */
318 /* Flags controling the set of information propagate_block collects. */
322 /* Store the data structures necessary for depth-first search. */
323 struct depth_first_search_dsS {
324 /* stack for backtracking during the algorithm */
327 /* number of edges in the stack. That is, positions 0, ..., sp-1
331 /* record of basic blocks already seen by depth-first search */
332 sbitmap visited_blocks;
334 typedef struct depth_first_search_dsS *depth_first_search_ds;
336 /* Forward declarations */
337 static int count_basic_blocks PARAMS ((rtx));
338 static void find_basic_blocks_1 PARAMS ((rtx));
339 static rtx find_label_refs PARAMS ((rtx, rtx));
340 static void clear_edges PARAMS ((void));
341 static void make_edges PARAMS ((rtx));
342 static void make_label_edge PARAMS ((sbitmap *, basic_block,
344 static void make_eh_edge PARAMS ((sbitmap *, eh_nesting_info *,
345 basic_block, rtx, int));
346 static void mark_critical_edges PARAMS ((void));
347 static void move_stray_eh_region_notes PARAMS ((void));
348 static void record_active_eh_regions PARAMS ((rtx));
350 static void commit_one_edge_insertion PARAMS ((edge));
352 static void delete_unreachable_blocks PARAMS ((void));
353 static void delete_eh_regions PARAMS ((void));
354 static int can_delete_note_p PARAMS ((rtx));
355 static void expunge_block PARAMS ((basic_block));
356 static int can_delete_label_p PARAMS ((rtx));
357 static int tail_recursion_label_p PARAMS ((rtx));
358 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
360 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
362 static int merge_blocks PARAMS ((edge,basic_block,basic_block));
363 static void try_merge_blocks PARAMS ((void));
364 static void tidy_fallthru_edges PARAMS ((void));
365 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
366 static void verify_wide_reg PARAMS ((int, rtx, rtx));
367 static void verify_local_live_at_start PARAMS ((regset, basic_block));
368 static int set_noop_p PARAMS ((rtx));
369 static int noop_move_p PARAMS ((rtx));
370 static void delete_noop_moves PARAMS ((rtx));
371 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
372 static void notice_stack_pointer_modification PARAMS ((rtx));
373 static void mark_reg PARAMS ((rtx, void *));
374 static void mark_regs_live_at_end PARAMS ((regset));
375 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
376 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
377 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
378 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
379 static int insn_dead_p PARAMS ((struct propagate_block_info *,
381 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
383 static void mark_set_regs PARAMS ((struct propagate_block_info *,
385 static void mark_set_1 PARAMS ((struct propagate_block_info *,
386 enum rtx_code, rtx, rtx,
388 #ifdef HAVE_conditional_execution
389 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
391 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
392 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
393 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
395 static rtx ior_reg_cond PARAMS ((rtx, rtx));
396 static rtx not_reg_cond PARAMS ((rtx));
397 static rtx nand_reg_cond PARAMS ((rtx, rtx));
400 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
401 rtx, rtx, rtx, rtx, rtx));
402 static void find_auto_inc PARAMS ((struct propagate_block_info *,
404 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
406 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
408 static void mark_used_reg PARAMS ((struct propagate_block_info *,
410 static void mark_used_regs PARAMS ((struct propagate_block_info *,
412 void dump_flow_info PARAMS ((FILE *));
413 void debug_flow_info PARAMS ((void));
414 static void dump_edge_info PARAMS ((FILE *, edge, int));
415 static void print_rtl_and_abort PARAMS ((void));
417 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
419 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
421 static void remove_fake_successors PARAMS ((basic_block));
422 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
424 static void flow_edge_list_print PARAMS ((const char *, const edge *,
426 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
428 static int flow_loop_nested_p PARAMS ((struct loop *,
430 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
432 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
433 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
434 static int flow_depth_first_order_compute PARAMS ((int *, int *));
435 static void flow_dfs_compute_reverse_init
436 PARAMS ((depth_first_search_ds));
437 static void flow_dfs_compute_reverse_add_bb
438 PARAMS ((depth_first_search_ds, basic_block));
439 static basic_block flow_dfs_compute_reverse_execute
440 PARAMS ((depth_first_search_ds));
441 static void flow_dfs_compute_reverse_finish
442 PARAMS ((depth_first_search_ds));
443 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
444 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
446 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
447 static void flow_loops_tree_build PARAMS ((struct loops *));
448 static int flow_loop_level_compute PARAMS ((struct loop *, int));
449 static int flow_loops_level_compute PARAMS ((struct loops *));
450 static void allocate_bb_life_data PARAMS ((void));
452 /* Find basic blocks of the current function.
453 F is the first insn of the function and NREGS the number of register
457 find_basic_blocks (f, nregs, file)
459 int nregs ATTRIBUTE_UNUSED;
460 FILE *file ATTRIBUTE_UNUSED;
464 /* Flush out existing data. */
465 if (basic_block_info != NULL)
471 /* Clear bb->aux on all extant basic blocks. We'll use this as a
472 tag for reuse during create_basic_block, just in case some pass
473 copies around basic block notes improperly. */
474 for (i = 0; i < n_basic_blocks; ++i)
475 BASIC_BLOCK (i)->aux = NULL;
477 VARRAY_FREE (basic_block_info);
480 n_basic_blocks = count_basic_blocks (f);
482 /* Size the basic block table. The actual structures will be allocated
483 by find_basic_blocks_1, since we want to keep the structure pointers
484 stable across calls to find_basic_blocks. */
485 /* ??? This whole issue would be much simpler if we called find_basic_blocks
486 exactly once, and thereafter we don't have a single long chain of
487 instructions at all until close to the end of compilation when we
488 actually lay them out. */
490 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
492 find_basic_blocks_1 (f);
494 /* Record the block to which an insn belongs. */
495 /* ??? This should be done another way, by which (perhaps) a label is
496 tagged directly with the basic block that it starts. It is used for
497 more than that currently, but IMO that is the only valid use. */
499 max_uid = get_max_uid ();
501 /* Leave space for insns life_analysis makes in some cases for auto-inc.
502 These cases are rare, so we don't need too much space. */
503 max_uid += max_uid / 10;
506 compute_bb_for_insn (max_uid);
508 /* Discover the edges of our cfg. */
509 record_active_eh_regions (f);
510 make_edges (label_value_list);
512 /* Do very simple cleanup now, for the benefit of code that runs between
513 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
514 tidy_fallthru_edges ();
516 mark_critical_edges ();
518 #ifdef ENABLE_CHECKING
524 check_function_return_warnings ()
526 if (warn_missing_noreturn
527 && !TREE_THIS_VOLATILE (cfun->decl)
528 && EXIT_BLOCK_PTR->pred == NULL)
529 warning ("function might be possible candidate for attribute `noreturn'");
531 /* If we have a path to EXIT, then we do return. */
532 if (TREE_THIS_VOLATILE (cfun->decl)
533 && EXIT_BLOCK_PTR->pred != NULL)
534 warning ("`noreturn' function does return");
536 /* If the clobber_return_insn appears in some basic block, then we
537 do reach the end without returning a value. */
538 else if (warn_return_type
539 && cfun->x_clobber_return_insn != NULL
540 && EXIT_BLOCK_PTR->pred != NULL)
542 int max_uid = get_max_uid ();
544 /* If clobber_return_insn was excised by jump1, then renumber_insns
545 can make max_uid smaller than the number still recorded in our rtx.
546 That's fine, since this is a quick way of verifying that the insn
547 is no longer in the chain. */
548 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
550 /* Recompute insn->block mapping, since the initial mapping is
551 set before we delete unreachable blocks. */
552 compute_bb_for_insn (max_uid);
554 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
555 warning ("control reaches end of non-void function");
560 /* Count the basic blocks of the function. */
563 count_basic_blocks (f)
567 register RTX_CODE prev_code;
568 register int count = 0;
570 int call_had_abnormal_edge = 0;
572 prev_code = JUMP_INSN;
573 for (insn = f; insn; insn = NEXT_INSN (insn))
575 register RTX_CODE code = GET_CODE (insn);
577 if (code == CODE_LABEL
578 || (GET_RTX_CLASS (code) == 'i'
579 && (prev_code == JUMP_INSN
580 || prev_code == BARRIER
581 || (prev_code == CALL_INSN && call_had_abnormal_edge))))
584 /* Record whether this call created an edge. */
585 if (code == CALL_INSN)
587 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
588 int region = (note ? INTVAL (XEXP (note, 0)) : 1);
590 call_had_abnormal_edge = 0;
592 /* If there is an EH region or rethrow, we have an edge. */
593 if ((eh_region && region > 0)
594 || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
595 call_had_abnormal_edge = 1;
596 else if (nonlocal_goto_handler_labels && region >= 0)
597 /* If there is a nonlocal goto label and the specified
598 region number isn't -1, we have an edge. (0 means
599 no throw, but might have a nonlocal goto). */
600 call_had_abnormal_edge = 1;
605 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
607 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
611 /* The rest of the compiler works a bit smoother when we don't have to
612 check for the edge case of do-nothing functions with no basic blocks. */
615 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
622 /* Scan a list of insns for labels referred to other than by jumps.
623 This is used to scan the alternatives of a call placeholder. */
625 find_label_refs (f, lvl)
631 for (insn = f; insn; insn = NEXT_INSN (insn))
636 /* Make a list of all labels referred to other than by jumps
637 (which just don't have the REG_LABEL notes).
639 Make a special exception for labels followed by an ADDR*VEC,
640 as this would be a part of the tablejump setup code.
642 Make a special exception for the eh_return_stub_label, which
643 we know isn't part of any otherwise visible control flow. */
645 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
646 if (REG_NOTE_KIND (note) == REG_LABEL)
648 rtx lab = XEXP (note, 0), next;
650 if (lab == eh_return_stub_label)
652 else if ((next = next_nonnote_insn (lab)) != NULL
653 && GET_CODE (next) == JUMP_INSN
654 && (GET_CODE (PATTERN (next)) == ADDR_VEC
655 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
657 else if (GET_CODE (lab) == NOTE)
660 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
667 /* Find all basic blocks of the function whose first insn is F.
669 Collect and return a list of labels whose addresses are taken. This
670 will be used in make_edges for use with computed gotos. */
673 find_basic_blocks_1 (f)
676 register rtx insn, next;
678 rtx bb_note = NULL_RTX;
679 rtx eh_list = NULL_RTX;
685 /* We process the instructions in a slightly different way than we did
686 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
687 closed out the previous block, so that it gets attached at the proper
688 place. Since this form should be equivalent to the previous,
689 count_basic_blocks continues to use the old form as a check. */
691 for (insn = f; insn; insn = next)
693 enum rtx_code code = GET_CODE (insn);
695 next = NEXT_INSN (insn);
701 int kind = NOTE_LINE_NUMBER (insn);
703 /* Keep a LIFO list of the currently active exception notes. */
704 if (kind == NOTE_INSN_EH_REGION_BEG)
705 eh_list = alloc_INSN_LIST (insn, eh_list);
706 else if (kind == NOTE_INSN_EH_REGION_END)
710 eh_list = XEXP (eh_list, 1);
711 free_INSN_LIST_node (t);
714 /* Look for basic block notes with which to keep the
715 basic_block_info pointers stable. Unthread the note now;
716 we'll put it back at the right place in create_basic_block.
717 Or not at all if we've already found a note in this block. */
718 else if (kind == NOTE_INSN_BASIC_BLOCK)
720 if (bb_note == NULL_RTX)
723 next = flow_delete_insn (insn);
729 /* A basic block starts at a label. If we've closed one off due
730 to a barrier or some such, no need to do it again. */
731 if (head != NULL_RTX)
733 /* While we now have edge lists with which other portions of
734 the compiler might determine a call ending a basic block
735 does not imply an abnormal edge, it will be a bit before
736 everything can be updated. So continue to emit a noop at
737 the end of such a block. */
738 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
740 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
741 end = emit_insn_after (nop, end);
744 create_basic_block (i++, head, end, bb_note);
752 /* A basic block ends at a jump. */
753 if (head == NULL_RTX)
757 /* ??? Make a special check for table jumps. The way this
758 happens is truly and amazingly gross. We are about to
759 create a basic block that contains just a code label and
760 an addr*vec jump insn. Worse, an addr_diff_vec creates
761 its own natural loop.
763 Prevent this bit of brain damage, pasting things together
764 correctly in make_edges.
766 The correct solution involves emitting the table directly
767 on the tablejump instruction as a note, or JUMP_LABEL. */
769 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
770 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
778 goto new_bb_inclusive;
781 /* A basic block ends at a barrier. It may be that an unconditional
782 jump already closed the basic block -- no need to do it again. */
783 if (head == NULL_RTX)
786 /* While we now have edge lists with which other portions of the
787 compiler might determine a call ending a basic block does not
788 imply an abnormal edge, it will be a bit before everything can
789 be updated. So continue to emit a noop at the end of such a
791 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
793 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
794 end = emit_insn_after (nop, end);
796 goto new_bb_exclusive;
800 /* Record whether this call created an edge. */
801 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
802 int region = (note ? INTVAL (XEXP (note, 0)) : 1);
803 int call_has_abnormal_edge = 0;
805 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
807 /* Scan each of the alternatives for label refs. */
808 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
809 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
810 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
811 /* Record its tail recursion label, if any. */
812 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
813 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
816 /* If there is an EH region or rethrow, we have an edge. */
817 if ((eh_list && region > 0)
818 || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
819 call_has_abnormal_edge = 1;
820 else if (nonlocal_goto_handler_labels && region >= 0)
821 /* If there is a nonlocal goto label and the specified
822 region number isn't -1, we have an edge. (0 means
823 no throw, but might have a nonlocal goto). */
824 call_has_abnormal_edge = 1;
826 /* A basic block ends at a call that can either throw or
827 do a non-local goto. */
828 if (call_has_abnormal_edge)
831 if (head == NULL_RTX)
836 create_basic_block (i++, head, end, bb_note);
837 head = end = NULL_RTX;
845 if (GET_RTX_CLASS (code) == 'i')
847 if (head == NULL_RTX)
854 if (GET_RTX_CLASS (code) == 'i')
858 /* Make a list of all labels referred to other than by jumps
859 (which just don't have the REG_LABEL notes).
861 Make a special exception for labels followed by an ADDR*VEC,
862 as this would be a part of the tablejump setup code.
864 Make a special exception for the eh_return_stub_label, which
865 we know isn't part of any otherwise visible control flow. */
867 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
868 if (REG_NOTE_KIND (note) == REG_LABEL)
870 rtx lab = XEXP (note, 0), next;
872 if (lab == eh_return_stub_label)
874 else if ((next = next_nonnote_insn (lab)) != NULL
875 && GET_CODE (next) == JUMP_INSN
876 && (GET_CODE (PATTERN (next)) == ADDR_VEC
877 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
879 else if (GET_CODE (lab) == NOTE)
882 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
887 if (head != NULL_RTX)
888 create_basic_block (i++, head, end, bb_note);
890 flow_delete_insn (bb_note);
892 if (i != n_basic_blocks)
895 label_value_list = lvl;
896 tail_recursion_label_list = trll;
899 /* Tidy the CFG by deleting unreachable code and whatnot. */
905 delete_unreachable_blocks ();
906 move_stray_eh_region_notes ();
907 record_active_eh_regions (f);
909 mark_critical_edges ();
911 /* Kill the data we won't maintain. */
912 free_EXPR_LIST_list (&label_value_list);
913 free_EXPR_LIST_list (&tail_recursion_label_list);
916 /* Create a new basic block consisting of the instructions between
917 HEAD and END inclusive. Reuses the note and basic block struct
918 in BB_NOTE, if any. */
921 create_basic_block (index, head, end, bb_note)
923 rtx head, end, bb_note;
928 && ! RTX_INTEGRATED_P (bb_note)
929 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
932 /* If we found an existing note, thread it back onto the chain. */
936 if (GET_CODE (head) == CODE_LABEL)
940 after = PREV_INSN (head);
944 if (after != bb_note && NEXT_INSN (after) != bb_note)
945 reorder_insns (bb_note, bb_note, after);
949 /* Otherwise we must create a note and a basic block structure.
950 Since we allow basic block structs in rtl, give the struct
951 the same lifetime by allocating it off the function obstack
952 rather than using malloc. */
954 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
955 memset (bb, 0, sizeof (*bb));
957 if (GET_CODE (head) == CODE_LABEL)
958 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
961 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
964 NOTE_BASIC_BLOCK (bb_note) = bb;
967 /* Always include the bb note in the block. */
968 if (NEXT_INSN (end) == bb_note)
974 BASIC_BLOCK (index) = bb;
976 /* Tag the block so that we know it has been used when considering
977 other basic block notes. */
981 /* Records the basic block struct in BB_FOR_INSN, for every instruction
982 indexed by INSN_UID. MAX is the size of the array. */
985 compute_bb_for_insn (max)
990 if (basic_block_for_insn)
991 VARRAY_FREE (basic_block_for_insn);
992 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
994 for (i = 0; i < n_basic_blocks; ++i)
996 basic_block bb = BASIC_BLOCK (i);
1003 int uid = INSN_UID (insn);
1005 VARRAY_BB (basic_block_for_insn, uid) = bb;
1008 insn = NEXT_INSN (insn);
1013 /* Free the memory associated with the edge structures. */
1021 for (i = 0; i < n_basic_blocks; ++i)
1023 basic_block bb = BASIC_BLOCK (i);
1025 for (e = bb->succ; e; e = n)
1035 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1041 ENTRY_BLOCK_PTR->succ = 0;
1042 EXIT_BLOCK_PTR->pred = 0;
1047 /* Identify the edges between basic blocks.
1049 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1050 that are otherwise unreachable may be reachable with a non-local goto.
1052 BB_EH_END is an array indexed by basic block number in which we record
1053 the list of exception regions active at the end of the basic block. */
1056 make_edges (label_value_list)
1057 rtx label_value_list;
1060 eh_nesting_info *eh_nest_info = init_eh_nesting_info ();
1061 sbitmap *edge_cache = NULL;
1063 /* Assume no computed jump; revise as we create edges. */
1064 current_function_has_computed_jump = 0;
1066 /* Heavy use of computed goto in machine-generated code can lead to
1067 nearly fully-connected CFGs. In that case we spend a significant
1068 amount of time searching the edge lists for duplicates. */
1069 if (forced_labels || label_value_list)
1071 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1072 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1075 /* By nature of the way these get numbered, block 0 is always the entry. */
1076 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1078 for (i = 0; i < n_basic_blocks; ++i)
1080 basic_block bb = BASIC_BLOCK (i);
1083 int force_fallthru = 0;
1085 /* Examine the last instruction of the block, and discover the
1086 ways we can leave the block. */
1089 code = GET_CODE (insn);
1092 if (code == JUMP_INSN)
1096 /* ??? Recognize a tablejump and do the right thing. */
1097 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1098 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1099 && GET_CODE (tmp) == JUMP_INSN
1100 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1101 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1106 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1107 vec = XVEC (PATTERN (tmp), 0);
1109 vec = XVEC (PATTERN (tmp), 1);
1111 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1112 make_label_edge (edge_cache, bb,
1113 XEXP (RTVEC_ELT (vec, j), 0), 0);
1115 /* Some targets (eg, ARM) emit a conditional jump that also
1116 contains the out-of-range target. Scan for these and
1117 add an edge if necessary. */
1118 if ((tmp = single_set (insn)) != NULL
1119 && SET_DEST (tmp) == pc_rtx
1120 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1121 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1122 make_label_edge (edge_cache, bb,
1123 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1125 #ifdef CASE_DROPS_THROUGH
1126 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1127 us naturally detecting fallthru into the next block. */
1132 /* If this is a computed jump, then mark it as reaching
1133 everything on the label_value_list and forced_labels list. */
1134 else if (computed_jump_p (insn))
1136 current_function_has_computed_jump = 1;
1138 for (x = label_value_list; x; x = XEXP (x, 1))
1139 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1141 for (x = forced_labels; x; x = XEXP (x, 1))
1142 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1145 /* Returns create an exit out. */
1146 else if (returnjump_p (insn))
1147 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1149 /* Otherwise, we have a plain conditional or unconditional jump. */
1152 if (! JUMP_LABEL (insn))
1154 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1158 /* If this is a sibling call insn, then this is in effect a
1159 combined call and return, and so we need an edge to the
1160 exit block. No need to worry about EH edges, since we
1161 wouldn't have created the sibling call in the first place. */
1163 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1164 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1165 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1167 /* If this is a CALL_INSN, then mark it as reaching the active EH
1168 handler for this CALL_INSN. If we're handling asynchronous
1169 exceptions then any insn can reach any of the active handlers.
1171 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1173 else if (code == CALL_INSN || asynchronous_exceptions)
1175 /* Add any appropriate EH edges. We do this unconditionally
1176 since there may be a REG_EH_REGION or REG_EH_RETHROW note
1177 on the call, and this needn't be within an EH region. */
1178 make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end);
1180 /* If we have asynchronous exceptions, do the same for *all*
1181 exception regions active in the block. */
1182 if (asynchronous_exceptions
1183 && bb->eh_beg != bb->eh_end)
1185 if (bb->eh_beg >= 0)
1186 make_eh_edge (edge_cache, eh_nest_info, bb,
1187 NULL_RTX, bb->eh_beg);
1189 for (x = bb->head; x != bb->end; x = NEXT_INSN (x))
1190 if (GET_CODE (x) == NOTE
1191 && (NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_BEG
1192 || NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_END))
1194 int region = NOTE_EH_HANDLER (x);
1195 make_eh_edge (edge_cache, eh_nest_info, bb,
1200 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1202 /* ??? This could be made smarter: in some cases it's possible
1203 to tell that certain calls will not do a nonlocal goto.
1205 For example, if the nested functions that do the nonlocal
1206 gotos do not have their addresses taken, then only calls to
1207 those functions or to other nested functions that use them
1208 could possibly do nonlocal gotos. */
1209 /* We do know that a REG_EH_REGION note with a value less
1210 than 0 is guaranteed not to perform a non-local goto. */
1211 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1212 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1213 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1214 make_label_edge (edge_cache, bb, XEXP (x, 0),
1215 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1219 /* We know something about the structure of the function __throw in
1220 libgcc2.c. It is the only function that ever contains eh_stub
1221 labels. It modifies its return address so that the last block
1222 returns to one of the eh_stub labels within it. So we have to
1223 make additional edges in the flow graph. */
1224 if (i + 1 == n_basic_blocks && eh_return_stub_label != 0)
1225 make_label_edge (edge_cache, bb, eh_return_stub_label, EDGE_EH);
1227 /* Find out if we can drop through to the next block. */
1228 insn = next_nonnote_insn (insn);
1229 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1230 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1231 else if (i + 1 < n_basic_blocks)
1233 rtx tmp = BLOCK_HEAD (i + 1);
1234 if (GET_CODE (tmp) == NOTE)
1235 tmp = next_nonnote_insn (tmp);
1236 if (force_fallthru || insn == tmp)
1237 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1241 free_eh_nesting_info (eh_nest_info);
1243 sbitmap_vector_free (edge_cache);
1246 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1247 about the edge that is accumulated between calls. */
1250 make_edge (edge_cache, src, dst, flags)
1251 sbitmap *edge_cache;
1252 basic_block src, dst;
1258 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1259 many edges to them, and we didn't allocate memory for it. */
1260 use_edge_cache = (edge_cache
1261 && src != ENTRY_BLOCK_PTR
1262 && dst != EXIT_BLOCK_PTR);
1264 /* Make sure we don't add duplicate edges. */
1265 switch (use_edge_cache)
1268 /* Quick test for non-existance of the edge. */
1269 if (! TEST_BIT (edge_cache[src->index], dst->index))
1272 /* The edge exists; early exit if no work to do. */
1278 for (e = src->succ; e; e = e->succ_next)
1287 e = (edge) xcalloc (1, sizeof (*e));
1290 e->succ_next = src->succ;
1291 e->pred_next = dst->pred;
1300 SET_BIT (edge_cache[src->index], dst->index);
1303 /* Create an edge from a basic block to a label. */
1306 make_label_edge (edge_cache, src, label, flags)
1307 sbitmap *edge_cache;
1312 if (GET_CODE (label) != CODE_LABEL)
1315 /* If the label was never emitted, this insn is junk, but avoid a
1316 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1317 as a result of a syntax error and a diagnostic has already been
1320 if (INSN_UID (label) == 0)
1323 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1326 /* Create the edges generated by INSN in REGION. */
1329 make_eh_edge (edge_cache, eh_nest_info, src, insn, region)
1330 sbitmap *edge_cache;
1331 eh_nesting_info *eh_nest_info;
1336 handler_info **handler_list;
1339 is_call = (insn && GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1340 num = reachable_handlers (region, eh_nest_info, insn, &handler_list);
1343 make_label_edge (edge_cache, src, handler_list[num]->handler_label,
1344 EDGE_ABNORMAL | EDGE_EH | is_call);
1348 /* EH_REGION notes appearing between basic blocks is ambiguous, and even
1349 dangerous if we intend to move basic blocks around. Move such notes
1350 into the following block. */
1353 move_stray_eh_region_notes ()
1358 if (n_basic_blocks < 2)
1361 b2 = BASIC_BLOCK (n_basic_blocks - 1);
1362 for (i = n_basic_blocks - 2; i >= 0; --i, b2 = b1)
1364 rtx insn, next, list = NULL_RTX;
1366 b1 = BASIC_BLOCK (i);
1367 for (insn = NEXT_INSN (b1->end); insn != b2->head; insn = next)
1369 next = NEXT_INSN (insn);
1370 if (GET_CODE (insn) == NOTE
1371 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1372 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1374 /* Unlink from the insn chain. */
1375 NEXT_INSN (PREV_INSN (insn)) = next;
1376 PREV_INSN (next) = PREV_INSN (insn);
1379 NEXT_INSN (insn) = list;
1384 if (list == NULL_RTX)
1387 /* Find where to insert these things. */
1389 if (GET_CODE (insn) == CODE_LABEL)
1390 insn = NEXT_INSN (insn);
1394 next = NEXT_INSN (list);
1395 add_insn_after (list, insn);
1401 /* Recompute eh_beg/eh_end for each basic block. */
1404 record_active_eh_regions (f)
1407 rtx insn, eh_list = NULL_RTX;
1409 basic_block bb = BASIC_BLOCK (0);
1411 for (insn = f; insn; insn = NEXT_INSN (insn))
1413 if (bb->head == insn)
1414 bb->eh_beg = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1416 if (GET_CODE (insn) == NOTE)
1418 int kind = NOTE_LINE_NUMBER (insn);
1419 if (kind == NOTE_INSN_EH_REGION_BEG)
1420 eh_list = alloc_INSN_LIST (insn, eh_list);
1421 else if (kind == NOTE_INSN_EH_REGION_END)
1423 rtx t = XEXP (eh_list, 1);
1424 free_INSN_LIST_node (eh_list);
1429 if (bb->end == insn)
1431 bb->eh_end = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1433 if (i == n_basic_blocks)
1435 bb = BASIC_BLOCK (i);
1440 /* Identify critical edges and set the bits appropriately. */
1443 mark_critical_edges ()
1445 int i, n = n_basic_blocks;
1448 /* We begin with the entry block. This is not terribly important now,
1449 but could be if a front end (Fortran) implemented alternate entry
1451 bb = ENTRY_BLOCK_PTR;
1458 /* (1) Critical edges must have a source with multiple successors. */
1459 if (bb->succ && bb->succ->succ_next)
1461 for (e = bb->succ; e; e = e->succ_next)
1463 /* (2) Critical edges must have a destination with multiple
1464 predecessors. Note that we know there is at least one
1465 predecessor -- the edge we followed to get here. */
1466 if (e->dest->pred->pred_next)
1467 e->flags |= EDGE_CRITICAL;
1469 e->flags &= ~EDGE_CRITICAL;
1474 for (e = bb->succ; e; e = e->succ_next)
1475 e->flags &= ~EDGE_CRITICAL;
1480 bb = BASIC_BLOCK (i);
1484 /* Split a block BB after insn INSN creating a new fallthru edge.
1485 Return the new edge. Note that to keep other parts of the compiler happy,
1486 this function renumbers all the basic blocks so that the new
1487 one has a number one greater than the block split. */
1490 split_block (bb, insn)
1500 /* There is no point splitting the block after its end. */
1501 if (bb->end == insn)
1504 /* Create the new structures. */
1505 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1506 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1509 memset (new_bb, 0, sizeof (*new_bb));
1511 new_bb->head = NEXT_INSN (insn);
1512 new_bb->end = bb->end;
1515 new_bb->succ = bb->succ;
1516 bb->succ = new_edge;
1517 new_bb->pred = new_edge;
1518 new_bb->count = bb->count;
1519 new_bb->loop_depth = bb->loop_depth;
1522 new_edge->dest = new_bb;
1523 new_edge->flags = EDGE_FALLTHRU;
1524 new_edge->probability = REG_BR_PROB_BASE;
1525 new_edge->count = bb->count;
1527 /* Redirect the src of the successor edges of bb to point to new_bb. */
1528 for (e = new_bb->succ; e; e = e->succ_next)
1531 /* Place the new block just after the block being split. */
1532 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1534 /* Some parts of the compiler expect blocks to be number in
1535 sequential order so insert the new block immediately after the
1536 block being split.. */
1538 for (i = n_basic_blocks - 1; i > j + 1; --i)
1540 basic_block tmp = BASIC_BLOCK (i - 1);
1541 BASIC_BLOCK (i) = tmp;
1545 BASIC_BLOCK (i) = 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;
1554 update_bb_for_insn (new_bb);
1556 if (bb->global_live_at_start)
1558 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1559 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1560 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1562 /* We now have to calculate which registers are live at the end
1563 of the split basic block and at the start of the new basic
1564 block. Start with those registers that are known to be live
1565 at the end of the original basic block and get
1566 propagate_block to determine which registers are live. */
1567 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1568 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1569 COPY_REG_SET (bb->global_live_at_end,
1570 new_bb->global_live_at_start);
1577 /* Split a (typically critical) edge. Return the new block.
1578 Abort on abnormal edges.
1580 ??? The code generally expects to be called on critical edges.
1581 The case of a block ending in an unconditional jump to a
1582 block with multiple predecessors is not handled optimally. */
1585 split_edge (edge_in)
1588 basic_block old_pred, bb, old_succ;
1593 /* Abnormal edges cannot be split. */
1594 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1597 old_pred = edge_in->src;
1598 old_succ = edge_in->dest;
1600 /* Remove the existing edge from the destination's pred list. */
1603 for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next)
1605 *pp = edge_in->pred_next;
1606 edge_in->pred_next = NULL;
1609 /* Create the new structures. */
1610 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1611 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
1614 memset (bb, 0, sizeof (*bb));
1616 /* ??? This info is likely going to be out of date very soon. */
1617 if (old_succ->global_live_at_start)
1619 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1620 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1621 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
1622 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
1627 bb->succ = edge_out;
1628 bb->count = edge_in->count;
1631 edge_in->flags &= ~EDGE_CRITICAL;
1633 edge_out->pred_next = old_succ->pred;
1634 edge_out->succ_next = NULL;
1636 edge_out->dest = old_succ;
1637 edge_out->flags = EDGE_FALLTHRU;
1638 edge_out->probability = REG_BR_PROB_BASE;
1639 edge_out->count = edge_in->count;
1641 old_succ->pred = edge_out;
1643 /* Tricky case -- if there existed a fallthru into the successor
1644 (and we're not it) we must add a new unconditional jump around
1645 the new block we're actually interested in.
1647 Further, if that edge is critical, this means a second new basic
1648 block must be created to hold it. In order to simplify correct
1649 insn placement, do this before we touch the existing basic block
1650 ordering for the block we were really wanting. */
1651 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1654 for (e = edge_out->pred_next; e; e = e->pred_next)
1655 if (e->flags & EDGE_FALLTHRU)
1660 basic_block jump_block;
1663 if ((e->flags & EDGE_CRITICAL) == 0
1664 && e->src != ENTRY_BLOCK_PTR)
1666 /* Non critical -- we can simply add a jump to the end
1667 of the existing predecessor. */
1668 jump_block = e->src;
1672 /* We need a new block to hold the jump. The simplest
1673 way to do the bulk of the work here is to recursively
1675 jump_block = split_edge (e);
1676 e = jump_block->succ;
1679 /* Now add the jump insn ... */
1680 pos = emit_jump_insn_after (gen_jump (old_succ->head),
1682 jump_block->end = pos;
1683 if (basic_block_for_insn)
1684 set_block_for_insn (pos, jump_block);
1685 emit_barrier_after (pos);
1687 /* ... let jump know that label is in use, ... */
1688 JUMP_LABEL (pos) = old_succ->head;
1689 ++LABEL_NUSES (old_succ->head);
1691 /* ... and clear fallthru on the outgoing edge. */
1692 e->flags &= ~EDGE_FALLTHRU;
1694 /* Continue splitting the interesting edge. */
1698 /* Place the new block just in front of the successor. */
1699 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1700 if (old_succ == EXIT_BLOCK_PTR)
1701 j = n_basic_blocks - 1;
1703 j = old_succ->index;
1704 for (i = n_basic_blocks - 1; i > j; --i)
1706 basic_block tmp = BASIC_BLOCK (i - 1);
1707 BASIC_BLOCK (i) = tmp;
1710 BASIC_BLOCK (i) = bb;
1713 /* Create the basic block note.
1715 Where we place the note can have a noticable impact on the generated
1716 code. Consider this cfg:
1726 If we need to insert an insn on the edge from block 0 to block 1,
1727 we want to ensure the instructions we insert are outside of any
1728 loop notes that physically sit between block 0 and block 1. Otherwise
1729 we confuse the loop optimizer into thinking the loop is a phony. */
1730 if (old_succ != EXIT_BLOCK_PTR
1731 && PREV_INSN (old_succ->head)
1732 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
1733 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
1734 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1735 PREV_INSN (old_succ->head));
1736 else if (old_succ != EXIT_BLOCK_PTR)
1737 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
1739 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
1740 NOTE_BASIC_BLOCK (bb_note) = bb;
1741 bb->head = bb->end = bb_note;
1743 /* Not quite simple -- for non-fallthru edges, we must adjust the
1744 predecessor's jump instruction to target our new block. */
1745 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1747 rtx tmp, insn = old_pred->end;
1748 rtx old_label = old_succ->head;
1749 rtx new_label = gen_label_rtx ();
1751 if (GET_CODE (insn) != JUMP_INSN)
1754 /* ??? Recognize a tablejump and adjust all matching cases. */
1755 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1756 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1757 && GET_CODE (tmp) == JUMP_INSN
1758 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1759 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1764 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1765 vec = XVEC (PATTERN (tmp), 0);
1767 vec = XVEC (PATTERN (tmp), 1);
1769 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1770 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1772 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
1773 --LABEL_NUSES (old_label);
1774 ++LABEL_NUSES (new_label);
1777 /* Handle casesi dispatch insns */
1778 if ((tmp = single_set (insn)) != NULL
1779 && SET_DEST (tmp) == pc_rtx
1780 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1781 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1782 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1784 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1786 --LABEL_NUSES (old_label);
1787 ++LABEL_NUSES (new_label);
1792 /* This would have indicated an abnormal edge. */
1793 if (computed_jump_p (insn))
1796 /* A return instruction can't be redirected. */
1797 if (returnjump_p (insn))
1800 /* If the insn doesn't go where we think, we're confused. */
1801 if (JUMP_LABEL (insn) != old_label)
1804 redirect_jump (insn, new_label, 0);
1807 emit_label_before (new_label, bb_note);
1808 bb->head = new_label;
1814 /* Queue instructions for insertion on an edge between two basic blocks.
1815 The new instructions and basic blocks (if any) will not appear in the
1816 CFG until commit_edge_insertions is called. */
1819 insert_insn_on_edge (pattern, e)
1823 /* We cannot insert instructions on an abnormal critical edge.
1824 It will be easier to find the culprit if we die now. */
1825 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
1826 == (EDGE_ABNORMAL|EDGE_CRITICAL))
1829 if (e->insns == NULL_RTX)
1832 push_to_sequence (e->insns);
1834 emit_insn (pattern);
1836 e->insns = get_insns ();
1840 /* Update the CFG for the instructions queued on edge E. */
1843 commit_one_edge_insertion (e)
1846 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1849 /* Pull the insns off the edge now since the edge might go away. */
1851 e->insns = NULL_RTX;
1853 /* Figure out where to put these things. If the destination has
1854 one predecessor, insert there. Except for the exit block. */
1855 if (e->dest->pred->pred_next == NULL
1856 && e->dest != EXIT_BLOCK_PTR)
1860 /* Get the location correct wrt a code label, and "nice" wrt
1861 a basic block note, and before everything else. */
1863 if (GET_CODE (tmp) == CODE_LABEL)
1864 tmp = NEXT_INSN (tmp);
1865 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1866 tmp = NEXT_INSN (tmp);
1867 if (tmp == bb->head)
1870 after = PREV_INSN (tmp);
1873 /* If the source has one successor and the edge is not abnormal,
1874 insert there. Except for the entry block. */
1875 else if ((e->flags & EDGE_ABNORMAL) == 0
1876 && e->src->succ->succ_next == NULL
1877 && e->src != ENTRY_BLOCK_PTR)
1880 /* It is possible to have a non-simple jump here. Consider a target
1881 where some forms of unconditional jumps clobber a register. This
1882 happens on the fr30 for example.
1884 We know this block has a single successor, so we can just emit
1885 the queued insns before the jump. */
1886 if (GET_CODE (bb->end) == JUMP_INSN)
1892 /* We'd better be fallthru, or we've lost track of what's what. */
1893 if ((e->flags & EDGE_FALLTHRU) == 0)
1900 /* Otherwise we must split the edge. */
1903 bb = split_edge (e);
1907 /* Now that we've found the spot, do the insertion. */
1909 /* Set the new block number for these insns, if structure is allocated. */
1910 if (basic_block_for_insn)
1913 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
1914 set_block_for_insn (i, bb);
1919 emit_insns_before (insns, before);
1920 if (before == bb->head)
1923 last = prev_nonnote_insn (before);
1927 last = emit_insns_after (insns, after);
1928 if (after == bb->end)
1932 if (returnjump_p (last))
1934 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1935 This is not currently a problem because this only happens
1936 for the (single) epilogue, which already has a fallthru edge
1940 if (e->dest != EXIT_BLOCK_PTR
1941 || e->succ_next != NULL
1942 || (e->flags & EDGE_FALLTHRU) == 0)
1944 e->flags &= ~EDGE_FALLTHRU;
1946 emit_barrier_after (last);
1950 flow_delete_insn (before);
1952 else if (GET_CODE (last) == JUMP_INSN)
1956 /* Update the CFG for all queued instructions. */
1959 commit_edge_insertions ()
1964 #ifdef ENABLE_CHECKING
1965 verify_flow_info ();
1969 bb = ENTRY_BLOCK_PTR;
1974 for (e = bb->succ; e; e = next)
1976 next = e->succ_next;
1978 commit_one_edge_insertion (e);
1981 if (++i >= n_basic_blocks)
1983 bb = BASIC_BLOCK (i);
1987 /* Delete all unreachable basic blocks. */
1990 delete_unreachable_blocks ()
1992 basic_block *worklist, *tos;
1993 int deleted_handler;
1998 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2000 /* Use basic_block->aux as a marker. Clear them all. */
2002 for (i = 0; i < n; ++i)
2003 BASIC_BLOCK (i)->aux = NULL;
2005 /* Add our starting points to the worklist. Almost always there will
2006 be only one. It isn't inconcievable that we might one day directly
2007 support Fortran alternate entry points. */
2009 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2013 /* Mark the block with a handy non-null value. */
2017 /* Iterate: find everything reachable from what we've already seen. */
2019 while (tos != worklist)
2021 basic_block b = *--tos;
2023 for (e = b->succ; e; e = e->succ_next)
2031 /* Delete all unreachable basic blocks. Count down so that we don't
2032 interfere with the block renumbering that happens in flow_delete_block. */
2034 deleted_handler = 0;
2036 for (i = n - 1; i >= 0; --i)
2038 basic_block b = BASIC_BLOCK (i);
2041 /* This block was found. Tidy up the mark. */
2044 deleted_handler |= flow_delete_block (b);
2047 tidy_fallthru_edges ();
2049 /* If we deleted an exception handler, we may have EH region begin/end
2050 blocks to remove as well. */
2051 if (deleted_handler)
2052 delete_eh_regions ();
2057 /* Find EH regions for which there is no longer a handler, and delete them. */
2060 delete_eh_regions ()
2064 update_rethrow_references ();
2066 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2067 if (GET_CODE (insn) == NOTE)
2069 if ((NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2070 || (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2072 int num = NOTE_EH_HANDLER (insn);
2073 /* A NULL handler indicates a region is no longer needed,
2074 as long as its rethrow label isn't used. */
2075 if (get_first_handler (num) == NULL && ! rethrow_used (num))
2077 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2078 NOTE_SOURCE_FILE (insn) = 0;
2084 /* Return true if NOTE is not one of the ones that must be kept paired,
2085 so that we may simply delete them. */
2088 can_delete_note_p (note)
2091 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2092 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2095 /* Unlink a chain of insns between START and FINISH, leaving notes
2096 that must be paired. */
2099 flow_delete_insn_chain (start, finish)
2102 /* Unchain the insns one by one. It would be quicker to delete all
2103 of these with a single unchaining, rather than one at a time, but
2104 we need to keep the NOTE's. */
2110 next = NEXT_INSN (start);
2111 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2113 else if (GET_CODE (start) == CODE_LABEL
2114 && ! can_delete_label_p (start))
2116 const char *name = LABEL_NAME (start);
2117 PUT_CODE (start, NOTE);
2118 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2119 NOTE_SOURCE_FILE (start) = name;
2122 next = flow_delete_insn (start);
2124 if (start == finish)
2130 /* Delete the insns in a (non-live) block. We physically delete every
2131 non-deleted-note insn, and update the flow graph appropriately.
2133 Return nonzero if we deleted an exception handler. */
2135 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2136 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2139 flow_delete_block (b)
2142 int deleted_handler = 0;
2145 /* If the head of this block is a CODE_LABEL, then it might be the
2146 label for an exception handler which can't be reached.
2148 We need to remove the label from the exception_handler_label list
2149 and remove the associated NOTE_INSN_EH_REGION_BEG and
2150 NOTE_INSN_EH_REGION_END notes. */
2154 never_reached_warning (insn);
2156 if (GET_CODE (insn) == CODE_LABEL)
2158 rtx x, *prev = &exception_handler_labels;
2160 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2162 if (XEXP (x, 0) == insn)
2164 /* Found a match, splice this label out of the EH label list. */
2165 *prev = XEXP (x, 1);
2166 XEXP (x, 1) = NULL_RTX;
2167 XEXP (x, 0) = NULL_RTX;
2169 /* Remove the handler from all regions */
2170 remove_handler (insn);
2171 deleted_handler = 1;
2174 prev = &XEXP (x, 1);
2178 /* Include any jump table following the basic block. */
2180 if (GET_CODE (end) == JUMP_INSN
2181 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2182 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2183 && GET_CODE (tmp) == JUMP_INSN
2184 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2185 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2188 /* Include any barrier that may follow the basic block. */
2189 tmp = next_nonnote_insn (end);
2190 if (tmp && GET_CODE (tmp) == BARRIER)
2193 /* Selectively delete the entire chain. */
2194 flow_delete_insn_chain (insn, end);
2196 /* Remove the edges into and out of this block. Note that there may
2197 indeed be edges in, if we are removing an unreachable loop. */
2201 for (e = b->pred; e; e = next)
2203 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2206 next = e->pred_next;
2210 for (e = b->succ; e; e = next)
2212 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2215 next = e->succ_next;
2224 /* Remove the basic block from the array, and compact behind it. */
2227 return deleted_handler;
2230 /* Remove block B from the basic block array and compact behind it. */
2236 int i, n = n_basic_blocks;
2238 for (i = b->index; i + 1 < n; ++i)
2240 basic_block x = BASIC_BLOCK (i + 1);
2241 BASIC_BLOCK (i) = x;
2245 basic_block_info->num_elements--;
2249 /* Delete INSN by patching it out. Return the next insn. */
2252 flow_delete_insn (insn)
2255 rtx prev = PREV_INSN (insn);
2256 rtx next = NEXT_INSN (insn);
2259 PREV_INSN (insn) = NULL_RTX;
2260 NEXT_INSN (insn) = NULL_RTX;
2261 INSN_DELETED_P (insn) = 1;
2264 NEXT_INSN (prev) = next;
2266 PREV_INSN (next) = prev;
2268 set_last_insn (prev);
2270 if (GET_CODE (insn) == CODE_LABEL)
2271 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2273 /* If deleting a jump, decrement the use count of the label. Deleting
2274 the label itself should happen in the normal course of block merging. */
2275 if (GET_CODE (insn) == JUMP_INSN
2276 && JUMP_LABEL (insn)
2277 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2278 LABEL_NUSES (JUMP_LABEL (insn))--;
2280 /* Also if deleting an insn that references a label. */
2281 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2282 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2283 LABEL_NUSES (XEXP (note, 0))--;
2288 /* True if a given label can be deleted. */
2291 can_delete_label_p (label)
2296 if (LABEL_PRESERVE_P (label))
2299 for (x = forced_labels; x; x = XEXP (x, 1))
2300 if (label == XEXP (x, 0))
2302 for (x = label_value_list; x; x = XEXP (x, 1))
2303 if (label == XEXP (x, 0))
2305 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2306 if (label == XEXP (x, 0))
2309 /* User declared labels must be preserved. */
2310 if (LABEL_NAME (label) != 0)
2317 tail_recursion_label_p (label)
2322 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2323 if (label == XEXP (x, 0))
2329 /* Blocks A and B are to be merged into a single block A. The insns
2330 are already contiguous, hence `nomove'. */
2333 merge_blocks_nomove (a, b)
2337 rtx b_head, b_end, a_end;
2338 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2341 /* If there was a CODE_LABEL beginning B, delete it. */
2344 if (GET_CODE (b_head) == CODE_LABEL)
2346 /* Detect basic blocks with nothing but a label. This can happen
2347 in particular at the end of a function. */
2348 if (b_head == b_end)
2350 del_first = del_last = b_head;
2351 b_head = NEXT_INSN (b_head);
2354 /* Delete the basic block note. */
2355 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2357 if (b_head == b_end)
2362 b_head = NEXT_INSN (b_head);
2365 /* If there was a jump out of A, delete it. */
2367 if (GET_CODE (a_end) == JUMP_INSN)
2371 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2372 if (GET_CODE (prev) != NOTE
2373 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2380 /* If this was a conditional jump, we need to also delete
2381 the insn that set cc0. */
2382 if (prev && sets_cc0_p (prev))
2385 prev = prev_nonnote_insn (prev);
2394 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2395 del_first = NEXT_INSN (a_end);
2397 /* Delete everything marked above as well as crap that might be
2398 hanging out between the two blocks. */
2399 flow_delete_insn_chain (del_first, del_last);
2401 /* Normally there should only be one successor of A and that is B, but
2402 partway though the merge of blocks for conditional_execution we'll
2403 be merging a TEST block with THEN and ELSE successors. Free the
2404 whole lot of them and hope the caller knows what they're doing. */
2406 remove_edge (a->succ);
2408 /* Adjust the edges out of B for the new owner. */
2409 for (e = b->succ; e; e = e->succ_next)
2413 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2414 b->pred = b->succ = NULL;
2416 /* Reassociate the insns of B with A. */
2419 if (basic_block_for_insn)
2421 BLOCK_FOR_INSN (b_head) = a;
2422 while (b_head != b_end)
2424 b_head = NEXT_INSN (b_head);
2425 BLOCK_FOR_INSN (b_head) = a;
2435 /* Blocks A and B are to be merged into a single block. A has no incoming
2436 fallthru edge, so it can be moved before B without adding or modifying
2437 any jumps (aside from the jump from A to B). */
2440 merge_blocks_move_predecessor_nojumps (a, b)
2443 rtx start, end, barrier;
2449 barrier = next_nonnote_insn (end);
2450 if (GET_CODE (barrier) != BARRIER)
2452 flow_delete_insn (barrier);
2454 /* Move block and loop notes out of the chain so that we do not
2455 disturb their order.
2457 ??? A better solution would be to squeeze out all the non-nested notes
2458 and adjust the block trees appropriately. Even better would be to have
2459 a tighter connection between block trees and rtl so that this is not
2461 start = squeeze_notes (start, end);
2463 /* Scramble the insn chain. */
2464 if (end != PREV_INSN (b->head))
2465 reorder_insns (start, end, PREV_INSN (b->head));
2469 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2470 a->index, b->index);
2473 /* Swap the records for the two blocks around. Although we are deleting B,
2474 A is now where B was and we want to compact the BB array from where
2476 BASIC_BLOCK (a->index) = b;
2477 BASIC_BLOCK (b->index) = a;
2479 a->index = b->index;
2482 /* Now blocks A and B are contiguous. Merge them. */
2483 merge_blocks_nomove (a, b);
2488 /* Blocks A and B are to be merged into a single block. B has no outgoing
2489 fallthru edge, so it can be moved after A without adding or modifying
2490 any jumps (aside from the jump from A to B). */
2493 merge_blocks_move_successor_nojumps (a, b)
2496 rtx start, end, barrier;
2500 barrier = NEXT_INSN (end);
2502 /* Recognize a jump table following block B. */
2503 if (GET_CODE (barrier) == CODE_LABEL
2504 && NEXT_INSN (barrier)
2505 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2506 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2507 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2509 end = NEXT_INSN (barrier);
2510 barrier = NEXT_INSN (end);
2513 /* There had better have been a barrier there. Delete it. */
2514 if (GET_CODE (barrier) != BARRIER)
2516 flow_delete_insn (barrier);
2518 /* Move block and loop notes out of the chain so that we do not
2519 disturb their order.
2521 ??? A better solution would be to squeeze out all the non-nested notes
2522 and adjust the block trees appropriately. Even better would be to have
2523 a tighter connection between block trees and rtl so that this is not
2525 start = squeeze_notes (start, end);
2527 /* Scramble the insn chain. */
2528 reorder_insns (start, end, a->end);
2530 /* Now blocks A and B are contiguous. Merge them. */
2531 merge_blocks_nomove (a, b);
2535 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2536 b->index, a->index);
2542 /* Attempt to merge basic blocks that are potentially non-adjacent.
2543 Return true iff the attempt succeeded. */
2546 merge_blocks (e, b, c)
2550 /* If C has a tail recursion label, do not merge. There is no
2551 edge recorded from the call_placeholder back to this label, as
2552 that would make optimize_sibling_and_tail_recursive_calls more
2553 complex for no gain. */
2554 if (GET_CODE (c->head) == CODE_LABEL
2555 && tail_recursion_label_p (c->head))
2558 /* If B has a fallthru edge to C, no need to move anything. */
2559 if (e->flags & EDGE_FALLTHRU)
2561 merge_blocks_nomove (b, c);
2565 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2566 b->index, c->index);
2575 int c_has_outgoing_fallthru;
2576 int b_has_incoming_fallthru;
2578 /* We must make sure to not munge nesting of exception regions,
2579 lexical blocks, and loop notes.
2581 The first is taken care of by requiring that the active eh
2582 region at the end of one block always matches the active eh
2583 region at the beginning of the next block.
2585 The later two are taken care of by squeezing out all the notes. */
2587 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2588 executed and we may want to treat blocks which have two out
2589 edges, one normal, one abnormal as only having one edge for
2590 block merging purposes. */
2592 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2593 if (tmp_edge->flags & EDGE_FALLTHRU)
2595 c_has_outgoing_fallthru = (tmp_edge != NULL);
2597 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2598 if (tmp_edge->flags & EDGE_FALLTHRU)
2600 b_has_incoming_fallthru = (tmp_edge != NULL);
2602 /* If B does not have an incoming fallthru, and the exception regions
2603 match, then it can be moved immediately before C without introducing
2606 C can not be the first block, so we do not have to worry about
2607 accessing a non-existent block. */
2608 d = BASIC_BLOCK (c->index - 1);
2609 if (! b_has_incoming_fallthru
2610 && d->eh_end == b->eh_beg
2611 && b->eh_end == c->eh_beg)
2612 return merge_blocks_move_predecessor_nojumps (b, c);
2614 /* Otherwise, we're going to try to move C after B. Make sure the
2615 exception regions match.
2617 If B is the last basic block, then we must not try to access the
2618 block structure for block B + 1. Luckily in that case we do not
2619 need to worry about matching exception regions. */
2620 d = (b->index + 1 < n_basic_blocks ? BASIC_BLOCK (b->index + 1) : NULL);
2621 if (b->eh_end == c->eh_beg
2622 && (d == NULL || c->eh_end == d->eh_beg))
2624 /* If C does not have an outgoing fallthru, then it can be moved
2625 immediately after B without introducing or modifying jumps. */
2626 if (! c_has_outgoing_fallthru)
2627 return merge_blocks_move_successor_nojumps (b, c);
2629 /* Otherwise, we'll need to insert an extra jump, and possibly
2630 a new block to contain it. */
2631 /* ??? Not implemented yet. */
2638 /* Top level driver for merge_blocks. */
2645 /* Attempt to merge blocks as made possible by edge removal. If a block
2646 has only one successor, and the successor has only one predecessor,
2647 they may be combined. */
2649 for (i = 0; i < n_basic_blocks;)
2651 basic_block c, b = BASIC_BLOCK (i);
2654 /* A loop because chains of blocks might be combineable. */
2655 while ((s = b->succ) != NULL
2656 && s->succ_next == NULL
2657 && (s->flags & EDGE_EH) == 0
2658 && (c = s->dest) != EXIT_BLOCK_PTR
2659 && c->pred->pred_next == NULL
2660 /* If the jump insn has side effects, we can't kill the edge. */
2661 && (GET_CODE (b->end) != JUMP_INSN
2662 || onlyjump_p (b->end))
2663 && merge_blocks (s, b, c))
2666 /* Don't get confused by the index shift caused by deleting blocks. */
2671 /* The given edge should potentially be a fallthru edge. If that is in
2672 fact true, delete the jump and barriers that are in the way. */
2675 tidy_fallthru_edge (e, b, c)
2681 /* ??? In a late-running flow pass, other folks may have deleted basic
2682 blocks by nopping out blocks, leaving multiple BARRIERs between here
2683 and the target label. They ought to be chastized and fixed.
2685 We can also wind up with a sequence of undeletable labels between
2686 one block and the next.
2688 So search through a sequence of barriers, labels, and notes for
2689 the head of block C and assert that we really do fall through. */
2691 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
2694 /* Remove what will soon cease being the jump insn from the source block.
2695 If block B consisted only of this single jump, turn it into a deleted
2698 if (GET_CODE (q) == JUMP_INSN
2700 && (any_uncondjump_p (q)
2701 || (b->succ == e && e->succ_next == NULL)))
2704 /* If this was a conditional jump, we need to also delete
2705 the insn that set cc0. */
2706 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
2713 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
2714 NOTE_SOURCE_FILE (q) = 0;
2722 /* Selectively unlink the sequence. */
2723 if (q != PREV_INSN (c->head))
2724 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
2726 e->flags |= EDGE_FALLTHRU;
2729 /* Fix up edges that now fall through, or rather should now fall through
2730 but previously required a jump around now deleted blocks. Simplify
2731 the search by only examining blocks numerically adjacent, since this
2732 is how find_basic_blocks created them. */
2735 tidy_fallthru_edges ()
2739 for (i = 1; i < n_basic_blocks; ++i)
2741 basic_block b = BASIC_BLOCK (i - 1);
2742 basic_block c = BASIC_BLOCK (i);
2745 /* We care about simple conditional or unconditional jumps with
2748 If we had a conditional branch to the next instruction when
2749 find_basic_blocks was called, then there will only be one
2750 out edge for the block which ended with the conditional
2751 branch (since we do not create duplicate edges).
2753 Furthermore, the edge will be marked as a fallthru because we
2754 merge the flags for the duplicate edges. So we do not want to
2755 check that the edge is not a FALLTHRU edge. */
2756 if ((s = b->succ) != NULL
2757 && s->succ_next == NULL
2759 /* If the jump insn has side effects, we can't tidy the edge. */
2760 && (GET_CODE (b->end) != JUMP_INSN
2761 || onlyjump_p (b->end)))
2762 tidy_fallthru_edge (s, b, c);
2766 /* Perform data flow analysis.
2767 F is the first insn of the function; FLAGS is a set of PROP_* flags
2768 to be used in accumulating flow info. */
2771 life_analysis (f, file, flags)
2776 #ifdef ELIMINABLE_REGS
2778 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
2781 /* Record which registers will be eliminated. We use this in
2784 CLEAR_HARD_REG_SET (elim_reg_set);
2786 #ifdef ELIMINABLE_REGS
2787 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
2788 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
2790 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
2794 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
2796 /* The post-reload life analysis have (on a global basis) the same
2797 registers live as was computed by reload itself. elimination
2798 Otherwise offsets and such may be incorrect.
2800 Reload will make some registers as live even though they do not
2803 We don't want to create new auto-incs after reload, since they
2804 are unlikely to be useful and can cause problems with shared
2806 if (reload_completed)
2807 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
2809 /* We want alias analysis information for local dead store elimination. */
2810 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2811 init_alias_analysis ();
2813 /* Always remove no-op moves. Do this before other processing so
2814 that we don't have to keep re-scanning them. */
2815 delete_noop_moves (f);
2817 /* Some targets can emit simpler epilogues if they know that sp was
2818 not ever modified during the function. After reload, of course,
2819 we've already emitted the epilogue so there's no sense searching. */
2820 if (! reload_completed)
2821 notice_stack_pointer_modification (f);
2823 /* Allocate and zero out data structures that will record the
2824 data from lifetime analysis. */
2825 allocate_reg_life_data ();
2826 allocate_bb_life_data ();
2828 /* Find the set of registers live on function exit. */
2829 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
2831 /* "Update" life info from zero. It'd be nice to begin the
2832 relaxation with just the exit and noreturn blocks, but that set
2833 is not immediately handy. */
2835 if (flags & PROP_REG_INFO)
2836 memset (regs_ever_live, 0, sizeof (regs_ever_live));
2837 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
2840 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2841 end_alias_analysis ();
2844 dump_flow_info (file);
2846 free_basic_block_vars (1);
2849 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2850 Search for REGNO. If found, abort if it is not wider than word_mode. */
2853 verify_wide_reg_1 (px, pregno)
2858 unsigned int regno = *(int *) pregno;
2860 if (GET_CODE (x) == REG && REGNO (x) == regno)
2862 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
2869 /* A subroutine of verify_local_live_at_start. Search through insns
2870 between HEAD and END looking for register REGNO. */
2873 verify_wide_reg (regno, head, end)
2880 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
2884 head = NEXT_INSN (head);
2887 /* We didn't find the register at all. Something's way screwy. */
2889 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
2890 print_rtl_and_abort ();
2893 /* A subroutine of update_life_info. Verify that there are no untoward
2894 changes in live_at_start during a local update. */
2897 verify_local_live_at_start (new_live_at_start, bb)
2898 regset new_live_at_start;
2901 if (reload_completed)
2903 /* After reload, there are no pseudos, nor subregs of multi-word
2904 registers. The regsets should exactly match. */
2905 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
2909 fprintf (rtl_dump_file,
2910 "live_at_start mismatch in bb %d, aborting\n",
2912 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
2913 debug_bitmap_file (rtl_dump_file, new_live_at_start);
2915 print_rtl_and_abort ();
2922 /* Find the set of changed registers. */
2923 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
2925 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
2927 /* No registers should die. */
2928 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
2931 fprintf (rtl_dump_file,
2932 "Register %d died unexpectedly in block %d\n", i,
2934 print_rtl_and_abort ();
2937 /* Verify that the now-live register is wider than word_mode. */
2938 verify_wide_reg (i, bb->head, bb->end);
2943 /* Updates life information starting with the basic blocks set in BLOCKS.
2944 If BLOCKS is null, consider it to be the universal set.
2946 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
2947 we are only expecting local modifications to basic blocks. If we find
2948 extra registers live at the beginning of a block, then we either killed
2949 useful data, or we have a broken split that wants data not provided.
2950 If we find registers removed from live_at_start, that means we have
2951 a broken peephole that is killing a register it shouldn't.
2953 ??? This is not true in one situation -- when a pre-reload splitter
2954 generates subregs of a multi-word pseudo, current life analysis will
2955 lose the kill. So we _can_ have a pseudo go live. How irritating.
2957 Including PROP_REG_INFO does not properly refresh regs_ever_live
2958 unless the caller resets it to zero. */
2961 update_life_info (blocks, extent, prop_flags)
2963 enum update_life_extent extent;
2967 regset_head tmp_head;
2970 tmp = INITIALIZE_REG_SET (tmp_head);
2972 /* For a global update, we go through the relaxation process again. */
2973 if (extent != UPDATE_LIFE_LOCAL)
2975 calculate_global_regs_live (blocks, blocks,
2976 prop_flags & PROP_SCAN_DEAD_CODE);
2978 /* If asked, remove notes from the blocks we'll update. */
2979 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
2980 count_or_remove_death_notes (blocks, 1);
2985 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2987 basic_block bb = BASIC_BLOCK (i);
2989 COPY_REG_SET (tmp, bb->global_live_at_end);
2990 propagate_block (bb, tmp, NULL, NULL, prop_flags);
2992 if (extent == UPDATE_LIFE_LOCAL)
2993 verify_local_live_at_start (tmp, bb);
2998 for (i = n_basic_blocks - 1; i >= 0; --i)
3000 basic_block bb = BASIC_BLOCK (i);
3002 COPY_REG_SET (tmp, bb->global_live_at_end);
3003 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3005 if (extent == UPDATE_LIFE_LOCAL)
3006 verify_local_live_at_start (tmp, bb);
3012 if (prop_flags & PROP_REG_INFO)
3014 /* The only pseudos that are live at the beginning of the function
3015 are those that were not set anywhere in the function. local-alloc
3016 doesn't know how to handle these correctly, so mark them as not
3017 local to any one basic block. */
3018 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
3019 FIRST_PSEUDO_REGISTER, i,
3020 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
3022 /* We have a problem with any pseudoreg that lives across the setjmp.
3023 ANSI says that if a user variable does not change in value between
3024 the setjmp and the longjmp, then the longjmp preserves it. This
3025 includes longjmp from a place where the pseudo appears dead.
3026 (In principle, the value still exists if it is in scope.)
3027 If the pseudo goes in a hard reg, some other value may occupy
3028 that hard reg where this pseudo is dead, thus clobbering the pseudo.
3029 Conclusion: such a pseudo must not go in a hard reg. */
3030 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
3031 FIRST_PSEUDO_REGISTER, i,
3033 if (regno_reg_rtx[i] != 0)
3035 REG_LIVE_LENGTH (i) = -1;
3036 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3042 /* Free the variables allocated by find_basic_blocks.
3044 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
3047 free_basic_block_vars (keep_head_end_p)
3048 int keep_head_end_p;
3050 if (basic_block_for_insn)
3052 VARRAY_FREE (basic_block_for_insn);
3053 basic_block_for_insn = NULL;
3056 if (! keep_head_end_p)
3059 VARRAY_FREE (basic_block_info);
3062 ENTRY_BLOCK_PTR->aux = NULL;
3063 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
3064 EXIT_BLOCK_PTR->aux = NULL;
3065 EXIT_BLOCK_PTR->global_live_at_start = NULL;
3069 /* Return nonzero if the destination of SET equals the source. */
3075 rtx src = SET_SRC (set);
3076 rtx dst = SET_DEST (set);
3078 if (GET_CODE (src) == SUBREG && GET_CODE (dst) == SUBREG)
3080 if (SUBREG_WORD (src) != SUBREG_WORD (dst))
3082 src = SUBREG_REG (src);
3083 dst = SUBREG_REG (dst);
3086 return (GET_CODE (src) == REG && GET_CODE (dst) == REG
3087 && REGNO (src) == REGNO (dst));
3090 /* Return nonzero if an insn consists only of SETs, each of which only sets a
3097 rtx pat = PATTERN (insn);
3099 /* Insns carrying these notes are useful later on. */
3100 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
3103 if (GET_CODE (pat) == SET && set_noop_p (pat))
3106 if (GET_CODE (pat) == PARALLEL)
3109 /* If nothing but SETs of registers to themselves,
3110 this insn can also be deleted. */
3111 for (i = 0; i < XVECLEN (pat, 0); i++)
3113 rtx tem = XVECEXP (pat, 0, i);
3115 if (GET_CODE (tem) == USE
3116 || GET_CODE (tem) == CLOBBER)
3119 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
3128 /* Delete any insns that copy a register to itself. */
3131 delete_noop_moves (f)
3135 for (insn = f; insn; insn = NEXT_INSN (insn))
3137 if (GET_CODE (insn) == INSN && noop_move_p (insn))
3139 PUT_CODE (insn, NOTE);
3140 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3141 NOTE_SOURCE_FILE (insn) = 0;
3146 /* Determine if the stack pointer is constant over the life of the function.
3147 Only useful before prologues have been emitted. */
3150 notice_stack_pointer_modification_1 (x, pat, data)
3152 rtx pat ATTRIBUTE_UNUSED;
3153 void *data ATTRIBUTE_UNUSED;
3155 if (x == stack_pointer_rtx
3156 /* The stack pointer is only modified indirectly as the result
3157 of a push until later in flow. See the comments in rtl.texi
3158 regarding Embedded Side-Effects on Addresses. */
3159 || (GET_CODE (x) == MEM
3160 && (GET_CODE (XEXP (x, 0)) == PRE_DEC
3161 || GET_CODE (XEXP (x, 0)) == PRE_INC
3162 || GET_CODE (XEXP (x, 0)) == POST_DEC
3163 || GET_CODE (XEXP (x, 0)) == POST_INC)
3164 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
3165 current_function_sp_is_unchanging = 0;
3169 notice_stack_pointer_modification (f)
3174 /* Assume that the stack pointer is unchanging if alloca hasn't
3176 current_function_sp_is_unchanging = !current_function_calls_alloca;
3177 if (! current_function_sp_is_unchanging)
3180 for (insn = f; insn; insn = NEXT_INSN (insn))
3184 /* Check if insn modifies the stack pointer. */
3185 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
3187 if (! current_function_sp_is_unchanging)
3193 /* Mark a register in SET. Hard registers in large modes get all
3194 of their component registers set as well. */
3197 mark_reg (reg, xset)
3201 regset set = (regset) xset;
3202 int regno = REGNO (reg);
3204 if (GET_MODE (reg) == BLKmode)
3207 SET_REGNO_REG_SET (set, regno);
3208 if (regno < FIRST_PSEUDO_REGISTER)
3210 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3212 SET_REGNO_REG_SET (set, regno + n);
3216 /* Mark those regs which are needed at the end of the function as live
3217 at the end of the last basic block. */
3220 mark_regs_live_at_end (set)
3225 /* If exiting needs the right stack value, consider the stack pointer
3226 live at the end of the function. */
3227 if ((HAVE_epilogue && reload_completed)
3228 || ! EXIT_IGNORE_STACK
3229 || (! FRAME_POINTER_REQUIRED
3230 && ! current_function_calls_alloca
3231 && flag_omit_frame_pointer)
3232 || current_function_sp_is_unchanging)
3234 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
3237 /* Mark the frame pointer if needed at the end of the function. If
3238 we end up eliminating it, it will be removed from the live list
3239 of each basic block by reload. */
3241 if (! reload_completed || frame_pointer_needed)
3243 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
3244 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3245 /* If they are different, also mark the hard frame pointer as live. */
3246 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
3247 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
3251 #ifdef PIC_OFFSET_TABLE_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 (fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3257 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 /* Mark all call-saved registers that we actaully used. */
3269 if (HAVE_epilogue && reload_completed)
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 /* Mark function return value. */
3277 diddle_return_value (mark_reg, set);
3280 /* Callback function for for_each_successor_phi. DATA is a regset.
3281 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3282 INSN, in the regset. */
3285 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
3286 rtx insn ATTRIBUTE_UNUSED;
3287 int dest_regno ATTRIBUTE_UNUSED;
3291 regset live = (regset) data;
3292 SET_REGNO_REG_SET (live, src_regno);
3296 /* Propagate global life info around the graph of basic blocks. Begin
3297 considering blocks with their corresponding bit set in BLOCKS_IN.
3298 If BLOCKS_IN is null, consider it the universal set.
3300 BLOCKS_OUT is set for every block that was changed. */
3303 calculate_global_regs_live (blocks_in, blocks_out, flags)
3304 sbitmap blocks_in, blocks_out;
3307 basic_block *queue, *qhead, *qtail, *qend;
3308 regset tmp, new_live_at_end;
3309 regset_head tmp_head;
3310 regset_head new_live_at_end_head;
3313 tmp = INITIALIZE_REG_SET (tmp_head);
3314 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
3316 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3317 because the `head == tail' style test for an empty queue doesn't
3318 work with a full queue. */
3319 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3321 qhead = qend = queue + n_basic_blocks + 2;
3323 /* Queue the blocks set in the initial mask. Do this in reverse block
3324 number order so that we are more likely for the first round to do
3325 useful work. We use AUX non-null to flag that the block is queued. */
3328 /* Clear out the garbage that might be hanging out in bb->aux. */
3329 for (i = n_basic_blocks - 1; i >= 0; --i)
3330 BASIC_BLOCK (i)->aux = NULL;
3332 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3334 basic_block bb = BASIC_BLOCK (i);
3341 for (i = 0; i < n_basic_blocks; ++i)
3343 basic_block bb = BASIC_BLOCK (i);
3350 sbitmap_zero (blocks_out);
3352 while (qhead != qtail)
3354 int rescan, changed;
3363 /* Begin by propogating live_at_start from the successor blocks. */
3364 CLEAR_REG_SET (new_live_at_end);
3365 for (e = bb->succ; e; e = e->succ_next)
3367 basic_block sb = e->dest;
3368 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3371 /* The all-important stack pointer must always be live. */
3372 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3374 /* Before reload, there are a few registers that must be forced
3375 live everywhere -- which might not already be the case for
3376 blocks within infinite loops. */
3377 if (! reload_completed)
3379 /* Any reference to any pseudo before reload is a potential
3380 reference of the frame pointer. */
3381 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3383 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3384 /* Pseudos with argument area equivalences may require
3385 reloading via the argument pointer. */
3386 if (fixed_regs[ARG_POINTER_REGNUM])
3387 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
3390 #ifdef PIC_OFFSET_TABLE_REGNUM
3391 /* Any constant, or pseudo with constant equivalences, may
3392 require reloading from memory using the pic register. */
3393 if (fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3394 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
3398 /* Regs used in phi nodes are not included in
3399 global_live_at_start, since they are live only along a
3400 particular edge. Set those regs that are live because of a
3401 phi node alternative corresponding to this particular block. */
3403 for_each_successor_phi (bb, &set_phi_alternative_reg,
3406 if (bb == ENTRY_BLOCK_PTR)
3408 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3412 /* On our first pass through this block, we'll go ahead and continue.
3413 Recognize first pass by local_set NULL. On subsequent passes, we
3414 get to skip out early if live_at_end wouldn't have changed. */
3416 if (bb->local_set == NULL)
3418 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3419 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3424 /* If any bits were removed from live_at_end, we'll have to
3425 rescan the block. This wouldn't be necessary if we had
3426 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3427 local_live is really dependent on live_at_end. */
3428 CLEAR_REG_SET (tmp);
3429 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3430 new_live_at_end, BITMAP_AND_COMPL);
3434 /* If any of the registers in the new live_at_end set are
3435 conditionally set in this basic block, we must rescan.
3436 This is because conditional lifetimes at the end of the
3437 block do not just take the live_at_end set into account,
3438 but also the liveness at the start of each successor
3439 block. We can miss changes in those sets if we only
3440 compare the new live_at_end against the previous one. */
3441 CLEAR_REG_SET (tmp);
3442 rescan = bitmap_operation (tmp, new_live_at_end,
3443 bb->cond_local_set, BITMAP_AND);
3448 /* Find the set of changed bits. Take this opportunity
3449 to notice that this set is empty and early out. */
3450 CLEAR_REG_SET (tmp);
3451 changed = bitmap_operation (tmp, bb->global_live_at_end,
3452 new_live_at_end, BITMAP_XOR);
3456 /* If any of the changed bits overlap with local_set,
3457 we'll have to rescan the block. Detect overlap by
3458 the AND with ~local_set turning off bits. */
3459 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3464 /* Let our caller know that BB changed enough to require its
3465 death notes updated. */
3467 SET_BIT (blocks_out, bb->index);
3471 /* Add to live_at_start the set of all registers in
3472 new_live_at_end that aren't in the old live_at_end. */
3474 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3476 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3478 changed = bitmap_operation (bb->global_live_at_start,
3479 bb->global_live_at_start,
3486 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3488 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3489 into live_at_start. */
3490 propagate_block (bb, new_live_at_end, bb->local_set,
3491 bb->cond_local_set, flags);
3493 /* If live_at start didn't change, no need to go farther. */
3494 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3497 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3500 /* Queue all predecessors of BB so that we may re-examine
3501 their live_at_end. */
3502 for (e = bb->pred; e; e = e->pred_next)
3504 basic_block pb = e->src;
3505 if (pb->aux == NULL)
3516 FREE_REG_SET (new_live_at_end);
3520 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3522 basic_block bb = BASIC_BLOCK (i);
3523 FREE_REG_SET (bb->local_set);
3524 FREE_REG_SET (bb->cond_local_set);
3529 for (i = n_basic_blocks - 1; i >= 0; --i)
3531 basic_block bb = BASIC_BLOCK (i);
3532 FREE_REG_SET (bb->local_set);
3533 FREE_REG_SET (bb->cond_local_set);
3540 /* Subroutines of life analysis. */
3542 /* Allocate the permanent data structures that represent the results
3543 of life analysis. Not static since used also for stupid life analysis. */
3546 allocate_bb_life_data ()
3550 for (i = 0; i < n_basic_blocks; i++)
3552 basic_block bb = BASIC_BLOCK (i);
3554 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3555 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3558 ENTRY_BLOCK_PTR->global_live_at_end
3559 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3560 EXIT_BLOCK_PTR->global_live_at_start
3561 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3563 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3567 allocate_reg_life_data ()
3571 max_regno = max_reg_num ();
3573 /* Recalculate the register space, in case it has grown. Old style
3574 vector oriented regsets would set regset_{size,bytes} here also. */
3575 allocate_reg_info (max_regno, FALSE, FALSE);
3577 /* Reset all the data we'll collect in propagate_block and its
3579 for (i = 0; i < max_regno; i++)
3583 REG_N_DEATHS (i) = 0;
3584 REG_N_CALLS_CROSSED (i) = 0;
3585 REG_LIVE_LENGTH (i) = 0;
3586 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3590 /* Delete dead instructions for propagate_block. */
3593 propagate_block_delete_insn (bb, insn)
3597 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3599 /* If the insn referred to a label, and that label was attached to
3600 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3601 pretty much mandatory to delete it, because the ADDR_VEC may be
3602 referencing labels that no longer exist. */
3606 rtx label = XEXP (inote, 0);
3609 if (LABEL_NUSES (label) == 1
3610 && (next = next_nonnote_insn (label)) != NULL
3611 && GET_CODE (next) == JUMP_INSN
3612 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3613 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3615 rtx pat = PATTERN (next);
3616 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3617 int len = XVECLEN (pat, diff_vec_p);
3620 for (i = 0; i < len; i++)
3621 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3623 flow_delete_insn (next);
3627 if (bb->end == insn)
3628 bb->end = PREV_INSN (insn);
3629 flow_delete_insn (insn);
3632 /* Delete dead libcalls for propagate_block. Return the insn
3633 before the libcall. */
3636 propagate_block_delete_libcall (bb, insn, note)
3640 rtx first = XEXP (note, 0);
3641 rtx before = PREV_INSN (first);
3643 if (insn == bb->end)
3646 flow_delete_insn_chain (first, insn);
3650 /* Update the life-status of regs for one insn. Return the previous insn. */
3653 propagate_one_insn (pbi, insn)
3654 struct propagate_block_info *pbi;
3657 rtx prev = PREV_INSN (insn);
3658 int flags = pbi->flags;
3659 int insn_is_dead = 0;
3660 int libcall_is_dead = 0;
3664 if (! INSN_P (insn))
3667 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3668 if (flags & PROP_SCAN_DEAD_CODE)
3670 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0,
3672 libcall_is_dead = (insn_is_dead && note != 0
3673 && libcall_dead_p (pbi, note, insn));
3676 /* We almost certainly don't want to delete prologue or epilogue
3677 instructions. Warn about probable compiler losage. */
3680 && (((HAVE_epilogue || HAVE_prologue)
3681 && prologue_epilogue_contains (insn))
3682 || (HAVE_sibcall_epilogue
3683 && sibcall_epilogue_contains (insn)))
3684 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
3686 if (flags & PROP_KILL_DEAD_CODE)
3688 warning ("ICE: would have deleted prologue/epilogue insn");
3689 if (!inhibit_warnings)
3692 libcall_is_dead = insn_is_dead = 0;
3695 /* If an instruction consists of just dead store(s) on final pass,
3697 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3699 /* Record sets. Do this even for dead instructions, since they
3700 would have killed the values if they hadn't been deleted. */
3701 mark_set_regs (pbi, PATTERN (insn), insn);
3703 /* CC0 is now known to be dead. Either this insn used it,
3704 in which case it doesn't anymore, or clobbered it,
3705 so the next insn can't use it. */
3708 if (libcall_is_dead)
3710 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
3711 insn = NEXT_INSN (prev);
3714 propagate_block_delete_insn (pbi->bb, insn);
3719 /* See if this is an increment or decrement that can be merged into
3720 a following memory address. */
3723 register rtx x = single_set (insn);
3725 /* Does this instruction increment or decrement a register? */
3726 if ((flags & PROP_AUTOINC)
3728 && GET_CODE (SET_DEST (x)) == REG
3729 && (GET_CODE (SET_SRC (x)) == PLUS
3730 || GET_CODE (SET_SRC (x)) == MINUS)
3731 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3732 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3733 /* Ok, look for a following memory ref we can combine with.
3734 If one is found, change the memory ref to a PRE_INC
3735 or PRE_DEC, cancel this insn, and return 1.
3736 Return 0 if nothing has been done. */
3737 && try_pre_increment_1 (pbi, insn))
3740 #endif /* AUTO_INC_DEC */
3742 CLEAR_REG_SET (pbi->new_set);
3744 /* If this is not the final pass, and this insn is copying the value of
3745 a library call and it's dead, don't scan the insns that perform the
3746 library call, so that the call's arguments are not marked live. */
3747 if (libcall_is_dead)
3749 /* Record the death of the dest reg. */
3750 mark_set_regs (pbi, PATTERN (insn), insn);
3752 insn = XEXP (note, 0);
3753 return PREV_INSN (insn);
3755 else if (GET_CODE (PATTERN (insn)) == SET
3756 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3757 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3758 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3759 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3760 /* We have an insn to pop a constant amount off the stack.
3761 (Such insns use PLUS regardless of the direction of the stack,
3762 and any insn to adjust the stack by a constant is always a pop.)
3763 These insns, if not dead stores, have no effect on life. */
3767 /* Any regs live at the time of a call instruction must not go
3768 in a register clobbered by calls. Find all regs now live and
3769 record this for them. */
3771 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
3772 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3773 { REG_N_CALLS_CROSSED (i)++; });
3775 /* Record sets. Do this even for dead instructions, since they
3776 would have killed the values if they hadn't been deleted. */
3777 mark_set_regs (pbi, PATTERN (insn), insn);
3779 if (GET_CODE (insn) == CALL_INSN)
3785 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3786 cond = COND_EXEC_TEST (PATTERN (insn));
3788 /* Non-constant calls clobber memory. */
3789 if (! CONST_CALL_P (insn))
3790 free_EXPR_LIST_list (&pbi->mem_set_list);
3792 /* There may be extra registers to be clobbered. */
3793 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3795 note = XEXP (note, 1))
3796 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
3797 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
3798 cond, insn, pbi->flags);
3800 /* Calls change all call-used and global registers. */
3801 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3802 if (call_used_regs[i] && ! global_regs[i]
3805 /* We do not want REG_UNUSED notes for these registers. */
3806 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
3808 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
3812 /* If an insn doesn't use CC0, it becomes dead since we assume
3813 that every insn clobbers it. So show it dead here;
3814 mark_used_regs will set it live if it is referenced. */
3819 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
3821 /* Sometimes we may have inserted something before INSN (such as a move)
3822 when we make an auto-inc. So ensure we will scan those insns. */
3824 prev = PREV_INSN (insn);
3827 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3833 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3834 cond = COND_EXEC_TEST (PATTERN (insn));
3836 /* Calls use their arguments. */
3837 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3839 note = XEXP (note, 1))
3840 if (GET_CODE (XEXP (note, 0)) == USE)
3841 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
3844 /* The stack ptr is used (honorarily) by a CALL insn. */
3845 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
3847 /* Calls may also reference any of the global registers,
3848 so they are made live. */
3849 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3851 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
3856 /* On final pass, update counts of how many insns in which each reg
3858 if (flags & PROP_REG_INFO)
3859 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3860 { REG_LIVE_LENGTH (i)++; });
3865 /* Initialize a propagate_block_info struct for public consumption.
3866 Note that the structure itself is opaque to this file, but that
3867 the user can use the regsets provided here. */
3869 struct propagate_block_info *
3870 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
3872 regset live, local_set, cond_local_set;
3875 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
3878 pbi->reg_live = live;
3879 pbi->mem_set_list = NULL_RTX;
3880 pbi->local_set = local_set;
3881 pbi->cond_local_set = cond_local_set;
3885 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3886 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
3888 pbi->reg_next_use = NULL;
3890 pbi->new_set = BITMAP_XMALLOC ();
3892 #ifdef HAVE_conditional_execution
3893 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
3894 free_reg_cond_life_info);
3895 pbi->reg_cond_reg = BITMAP_XMALLOC ();
3897 /* If this block ends in a conditional branch, for each register live
3898 from one side of the branch and not the other, record the register
3899 as conditionally dead. */
3900 if ((flags & (PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE))
3901 && GET_CODE (bb->end) == JUMP_INSN
3902 && any_condjump_p (bb->end))
3904 regset_head diff_head;
3905 regset diff = INITIALIZE_REG_SET (diff_head);
3906 basic_block bb_true, bb_false;
3907 rtx cond_true, cond_false, set_src;
3910 /* Identify the successor blocks. */
3911 bb_true = bb->succ->dest;
3912 if (bb->succ->succ_next != NULL)
3914 bb_false = bb->succ->succ_next->dest;
3916 if (bb->succ->flags & EDGE_FALLTHRU)
3918 basic_block t = bb_false;
3922 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
3927 /* This can happen with a conditional jump to the next insn. */
3928 if (JUMP_LABEL (bb->end) != bb_true->head)
3931 /* Simplest way to do nothing. */
3935 /* Extract the condition from the branch. */
3936 set_src = SET_SRC (pc_set (bb->end));
3937 cond_true = XEXP (set_src, 0);
3938 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
3939 GET_MODE (cond_true), XEXP (cond_true, 0),
3940 XEXP (cond_true, 1));
3941 if (GET_CODE (XEXP (set_src, 1)) == PC)
3944 cond_false = cond_true;
3948 /* Compute which register lead different lives in the successors. */
3949 if (bitmap_operation (diff, bb_true->global_live_at_start,
3950 bb_false->global_live_at_start, BITMAP_XOR))
3952 rtx reg = XEXP (cond_true, 0);
3954 if (GET_CODE (reg) == SUBREG)
3955 reg = SUBREG_REG (reg);
3957 if (GET_CODE (reg) != REG)
3960 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
3962 /* For each such register, mark it conditionally dead. */
3963 EXECUTE_IF_SET_IN_REG_SET
3966 struct reg_cond_life_info *rcli;
3969 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3971 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
3975 rcli->condition = alloc_EXPR_LIST (0, cond, NULL_RTX);
3977 splay_tree_insert (pbi->reg_cond_dead, i,
3978 (splay_tree_value) rcli);
3982 FREE_REG_SET (diff);
3986 /* If this block has no successors, any stores to the frame that aren't
3987 used later in the block are dead. So make a pass over the block
3988 recording any such that are made and show them dead at the end. We do
3989 a very conservative and simple job here. */
3991 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
3992 && (TYPE_RETURNS_STACK_DEPRESSED
3993 (TREE_TYPE (current_function_decl))))
3994 && (flags & PROP_SCAN_DEAD_CODE)
3995 && (bb->succ == NULL
3996 || (bb->succ->succ_next == NULL
3997 && bb->succ->dest == EXIT_BLOCK_PTR)))
4000 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
4001 if (GET_CODE (insn) == INSN
4002 && GET_CODE (PATTERN (insn)) == SET
4003 && GET_CODE (SET_DEST (PATTERN (insn))) == MEM)
4005 rtx mem = SET_DEST (PATTERN (insn));
4007 if (XEXP (mem, 0) == frame_pointer_rtx
4008 || (GET_CODE (XEXP (mem, 0)) == PLUS
4009 && XEXP (XEXP (mem, 0), 0) == frame_pointer_rtx
4010 && GET_CODE (XEXP (XEXP (mem, 0), 1)) == CONST_INT))
4013 /* Store a copy of mem, otherwise the address may be scrogged
4014 by find_auto_inc. This matters because insn_dead_p uses
4015 an rtx_equal_p check to determine if two addresses are
4016 the same. This works before find_auto_inc, but fails
4017 after find_auto_inc, causing discrepencies between the
4018 set of live registers calculated during the
4019 calculate_global_regs_live phase and what actually exists
4020 after flow completes, leading to aborts. */
4021 if (flags & PROP_AUTOINC)
4022 mem = shallow_copy_rtx (mem);
4024 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
4032 /* Release a propagate_block_info struct. */
4035 free_propagate_block_info (pbi)
4036 struct propagate_block_info *pbi;
4038 free_EXPR_LIST_list (&pbi->mem_set_list);
4040 BITMAP_XFREE (pbi->new_set);
4042 #ifdef HAVE_conditional_execution
4043 splay_tree_delete (pbi->reg_cond_dead);
4044 BITMAP_XFREE (pbi->reg_cond_reg);
4047 if (pbi->reg_next_use)
4048 free (pbi->reg_next_use);
4053 /* Compute the registers live at the beginning of a basic block BB from
4054 those live at the end.
4056 When called, REG_LIVE contains those live at the end. On return, it
4057 contains those live at the beginning.
4059 LOCAL_SET, if non-null, will be set with all registers killed
4060 unconditionally by this basic block.
4061 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
4062 killed conditionally by this basic block. If there is any unconditional
4063 set of a register, then the corresponding bit will be set in LOCAL_SET
4064 and cleared in COND_LOCAL_SET.
4065 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
4066 case, the resulting set will be equal to the union of the two sets that
4067 would otherwise be computed. */
4070 propagate_block (bb, live, local_set, cond_local_set, flags)
4074 regset cond_local_set;
4077 struct propagate_block_info *pbi;
4080 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
4082 if (flags & PROP_REG_INFO)
4086 /* Process the regs live at the end of the block.
4087 Mark them as not local to any one basic block. */
4088 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
4089 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4092 /* Scan the block an insn at a time from end to beginning. */
4094 for (insn = bb->end;; insn = prev)
4096 /* If this is a call to `setjmp' et al, warn if any
4097 non-volatile datum is live. */
4098 if ((flags & PROP_REG_INFO)
4099 && GET_CODE (insn) == NOTE
4100 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
4101 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
4103 prev = propagate_one_insn (pbi, insn);
4105 if (insn == bb->head)
4109 free_propagate_block_info (pbi);
4112 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
4113 (SET expressions whose destinations are registers dead after the insn).
4114 NEEDED is the regset that says which regs are alive after the insn.
4116 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
4118 If X is the entire body of an insn, NOTES contains the reg notes
4119 pertaining to the insn. */
4122 insn_dead_p (pbi, x, call_ok, notes)
4123 struct propagate_block_info *pbi;
4126 rtx notes ATTRIBUTE_UNUSED;
4128 enum rtx_code code = GET_CODE (x);
4131 /* If flow is invoked after reload, we must take existing AUTO_INC
4132 expresions into account. */
4133 if (reload_completed)
4135 for (; notes; notes = XEXP (notes, 1))
4137 if (REG_NOTE_KIND (notes) == REG_INC)
4139 int regno = REGNO (XEXP (notes, 0));
4141 /* Don't delete insns to set global regs. */
4142 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4143 || REGNO_REG_SET_P (pbi->reg_live, regno))
4150 /* If setting something that's a reg or part of one,
4151 see if that register's altered value will be live. */
4155 rtx r = SET_DEST (x);
4158 if (GET_CODE (r) == CC0)
4159 return ! pbi->cc0_live;
4162 /* A SET that is a subroutine call cannot be dead. */
4163 if (GET_CODE (SET_SRC (x)) == CALL)
4169 /* Don't eliminate loads from volatile memory or volatile asms. */
4170 else if (volatile_refs_p (SET_SRC (x)))
4173 if (GET_CODE (r) == MEM)
4177 if (MEM_VOLATILE_P (r))
4180 /* Walk the set of memory locations we are currently tracking
4181 and see if one is an identical match to this memory location.
4182 If so, this memory write is dead (remember, we're walking
4183 backwards from the end of the block to the start). */
4184 temp = pbi->mem_set_list;
4187 rtx mem = XEXP (temp, 0);
4189 if (rtx_equal_p (mem, r))
4192 /* Check if memory reference matches an auto increment. Only
4193 post increment/decrement or modify are valid. */
4194 if (GET_MODE (mem) == GET_MODE (r)
4195 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4196 || GET_CODE (XEXP (mem, 0)) == POST_INC
4197 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4198 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4199 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4202 temp = XEXP (temp, 1);
4207 while (GET_CODE (r) == SUBREG
4208 || GET_CODE (r) == STRICT_LOW_PART
4209 || GET_CODE (r) == ZERO_EXTRACT)
4212 if (GET_CODE (r) == REG)
4214 int regno = REGNO (r);
4217 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4220 /* If this is a hard register, verify that subsequent
4221 words are not needed. */
4222 if (regno < FIRST_PSEUDO_REGISTER)
4224 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4227 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4231 /* Don't delete insns to set global regs. */
4232 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4235 /* Make sure insns to set the stack pointer aren't deleted. */
4236 if (regno == STACK_POINTER_REGNUM)
4239 /* ??? These bits might be redundant with the force live bits
4240 in calculate_global_regs_live. We would delete from
4241 sequential sets; whether this actually affects real code
4242 for anything but the stack pointer I don't know. */
4243 /* Make sure insns to set the frame pointer aren't deleted. */
4244 if (regno == FRAME_POINTER_REGNUM
4245 && (! reload_completed || frame_pointer_needed))
4247 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4248 if (regno == HARD_FRAME_POINTER_REGNUM
4249 && (! reload_completed || frame_pointer_needed))
4253 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4254 /* Make sure insns to set arg pointer are never deleted
4255 (if the arg pointer isn't fixed, there will be a USE
4256 for it, so we can treat it normally). */
4257 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4261 /* Otherwise, the set is dead. */
4267 /* If performing several activities, insn is dead if each activity
4268 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4269 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4271 else if (code == PARALLEL)
4273 int i = XVECLEN (x, 0);
4275 for (i--; i >= 0; i--)
4276 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4277 && GET_CODE (XVECEXP (x, 0, i)) != USE
4278 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4284 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4285 is not necessarily true for hard registers. */
4286 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4287 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4288 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4291 /* We do not check other CLOBBER or USE here. An insn consisting of just
4292 a CLOBBER or just a USE should not be deleted. */
4296 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4297 return 1 if the entire library call is dead.
4298 This is true if INSN copies a register (hard or pseudo)
4299 and if the hard return reg of the call insn is dead.
4300 (The caller should have tested the destination of the SET inside
4301 INSN already for death.)
4303 If this insn doesn't just copy a register, then we don't
4304 have an ordinary libcall. In that case, cse could not have
4305 managed to substitute the source for the dest later on,
4306 so we can assume the libcall is dead.
4308 PBI is the block info giving pseudoregs live before this insn.
4309 NOTE is the REG_RETVAL note of the insn. */
4312 libcall_dead_p (pbi, note, insn)
4313 struct propagate_block_info *pbi;
4317 rtx x = single_set (insn);
4321 register rtx r = SET_SRC (x);
4322 if (GET_CODE (r) == REG)
4324 rtx call = XEXP (note, 0);
4328 /* Find the call insn. */
4329 while (call != insn && GET_CODE (call) != CALL_INSN)
4330 call = NEXT_INSN (call);
4332 /* If there is none, do nothing special,
4333 since ordinary death handling can understand these insns. */
4337 /* See if the hard reg holding the value is dead.
4338 If this is a PARALLEL, find the call within it. */
4339 call_pat = PATTERN (call);
4340 if (GET_CODE (call_pat) == PARALLEL)
4342 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4343 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4344 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4347 /* This may be a library call that is returning a value
4348 via invisible pointer. Do nothing special, since
4349 ordinary death handling can understand these insns. */
4353 call_pat = XVECEXP (call_pat, 0, i);
4356 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4362 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4363 live at function entry. Don't count global register variables, variables
4364 in registers that can be used for function arg passing, or variables in
4365 fixed hard registers. */
4368 regno_uninitialized (regno)
4371 if (n_basic_blocks == 0
4372 || (regno < FIRST_PSEUDO_REGISTER
4373 && (global_regs[regno]
4374 || fixed_regs[regno]
4375 || FUNCTION_ARG_REGNO_P (regno))))
4378 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
4381 /* 1 if register REGNO was alive at a place where `setjmp' was called
4382 and was set more than once or is an argument.
4383 Such regs may be clobbered by `longjmp'. */
4386 regno_clobbered_at_setjmp (regno)
4389 if (n_basic_blocks == 0)
4392 return ((REG_N_SETS (regno) > 1
4393 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
4394 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
4397 /* INSN references memory, possibly using autoincrement addressing modes.
4398 Find any entries on the mem_set_list that need to be invalidated due
4399 to an address change. */
4402 invalidate_mems_from_autoinc (pbi, insn)
4403 struct propagate_block_info *pbi;
4406 rtx note = REG_NOTES (insn);
4407 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
4409 if (REG_NOTE_KIND (note) == REG_INC)
4411 rtx temp = pbi->mem_set_list;
4412 rtx prev = NULL_RTX;
4417 next = XEXP (temp, 1);
4418 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
4420 /* Splice temp out of list. */
4422 XEXP (prev, 1) = next;
4424 pbi->mem_set_list = next;
4425 free_EXPR_LIST_node (temp);
4435 /* EXP is either a MEM or a REG. Remove any dependant entries
4436 from pbi->mem_set_list. */
4439 invalidate_mems_from_set (pbi, exp)
4440 struct propagate_block_info *pbi;
4443 rtx temp = pbi->mem_set_list;
4444 rtx prev = NULL_RTX;
4449 next = XEXP (temp, 1);
4450 if ((GET_CODE (exp) == MEM
4451 && output_dependence (XEXP (temp, 0), exp))
4452 || (GET_CODE (exp) == REG
4453 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
4455 /* Splice this entry out of the list. */
4457 XEXP (prev, 1) = next;
4459 pbi->mem_set_list = next;
4460 free_EXPR_LIST_node (temp);
4468 /* Process the registers that are set within X. Their bits are set to
4469 1 in the regset DEAD, because they are dead prior to this insn.
4471 If INSN is nonzero, it is the insn being processed.
4473 FLAGS is the set of operations to perform. */
4476 mark_set_regs (pbi, x, insn)
4477 struct propagate_block_info *pbi;
4480 rtx cond = NULL_RTX;
4485 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
4487 if (REG_NOTE_KIND (link) == REG_INC)
4488 mark_set_1 (pbi, SET, XEXP (link, 0),
4489 (GET_CODE (x) == COND_EXEC
4490 ? COND_EXEC_TEST (x) : NULL_RTX),
4494 switch (code = GET_CODE (x))
4498 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
4502 cond = COND_EXEC_TEST (x);
4503 x = COND_EXEC_CODE (x);
4509 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
4511 rtx sub = XVECEXP (x, 0, i);
4512 switch (code = GET_CODE (sub))
4515 if (cond != NULL_RTX)
4518 cond = COND_EXEC_TEST (sub);
4519 sub = COND_EXEC_CODE (sub);
4520 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
4526 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
4541 /* Process a single SET rtx, X. */
4544 mark_set_1 (pbi, code, reg, cond, insn, flags)
4545 struct propagate_block_info *pbi;
4547 rtx reg, cond, insn;
4550 int regno_first = -1, regno_last = -1;
4554 /* Some targets place small structures in registers for
4555 return values of functions. We have to detect this
4556 case specially here to get correct flow information. */
4557 if (GET_CODE (reg) == PARALLEL
4558 && GET_MODE (reg) == BLKmode)
4560 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
4561 mark_set_1 (pbi, code, XVECEXP (reg, 0, i), cond, insn, flags);
4565 /* Modifying just one hardware register of a multi-reg value or just a
4566 byte field of a register does not mean the value from before this insn
4567 is now dead. Of course, if it was dead after it's unused now. */
4569 switch (GET_CODE (reg))
4573 case STRICT_LOW_PART:
4574 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4576 reg = XEXP (reg, 0);
4577 while (GET_CODE (reg) == SUBREG
4578 || GET_CODE (reg) == ZERO_EXTRACT
4579 || GET_CODE (reg) == SIGN_EXTRACT
4580 || GET_CODE (reg) == STRICT_LOW_PART);
4581 if (GET_CODE (reg) == MEM)
4583 not_dead = REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
4587 regno_last = regno_first = REGNO (reg);
4588 if (regno_first < FIRST_PSEUDO_REGISTER)
4589 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
4593 if (GET_CODE (SUBREG_REG (reg)) == REG)
4595 enum machine_mode outer_mode = GET_MODE (reg);
4596 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
4598 /* Identify the range of registers affected. This is moderately
4599 tricky for hard registers. See alter_subreg. */
4601 regno_last = regno_first = REGNO (SUBREG_REG (reg));
4602 if (regno_first < FIRST_PSEUDO_REGISTER)
4604 #ifdef ALTER_HARD_SUBREG
4605 regno_first = ALTER_HARD_SUBREG (outer_mode, SUBREG_WORD (reg),
4606 inner_mode, regno_first);
4608 regno_first += SUBREG_WORD (reg);
4610 regno_last = (regno_first
4611 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
4613 /* Since we've just adjusted the register number ranges, make
4614 sure REG matches. Otherwise some_was_live will be clear
4615 when it shouldn't have been, and we'll create incorrect
4616 REG_UNUSED notes. */
4617 reg = gen_rtx_REG (outer_mode, regno_first);
4621 /* If the number of words in the subreg is less than the number
4622 of words in the full register, we have a well-defined partial
4623 set. Otherwise the high bits are undefined.
4625 This is only really applicable to pseudos, since we just took
4626 care of multi-word hard registers. */
4627 if (((GET_MODE_SIZE (outer_mode)
4628 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
4629 < ((GET_MODE_SIZE (inner_mode)
4630 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
4631 not_dead = REGNO_REG_SET_P (pbi->reg_live, regno_first);
4633 reg = SUBREG_REG (reg);
4637 reg = SUBREG_REG (reg);
4644 /* If this set is a MEM, then it kills any aliased writes.
4645 If this set is a REG, then it kills any MEMs which use the reg. */
4646 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4648 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
4649 invalidate_mems_from_set (pbi, reg);
4651 /* If the memory reference had embedded side effects (autoincrement
4652 address modes. Then we may need to kill some entries on the
4654 if (insn && GET_CODE (reg) == MEM)
4655 invalidate_mems_from_autoinc (pbi, insn);
4657 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
4658 /* ??? With more effort we could track conditional memory life. */
4660 /* We do not know the size of a BLKmode store, so we do not track
4661 them for redundant store elimination. */
4662 && GET_MODE (reg) != BLKmode
4663 /* There are no REG_INC notes for SP, so we can't assume we'll see
4664 everything that invalidates it. To be safe, don't eliminate any
4665 stores though SP; none of them should be redundant anyway. */
4666 && ! reg_mentioned_p (stack_pointer_rtx, reg))
4669 /* Store a copy of mem, otherwise the address may be
4670 scrogged by find_auto_inc. */
4671 if (flags & PROP_AUTOINC)
4672 reg = shallow_copy_rtx (reg);
4674 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
4678 if (GET_CODE (reg) == REG
4679 && ! (regno_first == FRAME_POINTER_REGNUM
4680 && (! reload_completed || frame_pointer_needed))
4681 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4682 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
4683 && (! reload_completed || frame_pointer_needed))
4685 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4686 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
4690 int some_was_live = 0, some_was_dead = 0;
4692 for (i = regno_first; i <= regno_last; ++i)
4694 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
4697 /* Order of the set operation matters here since both
4698 sets may be the same. */
4699 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
4700 if (cond != NULL_RTX
4701 && ! REGNO_REG_SET_P (pbi->local_set, i))
4702 SET_REGNO_REG_SET (pbi->cond_local_set, i);
4704 SET_REGNO_REG_SET (pbi->local_set, i);
4706 if (code != CLOBBER)
4707 SET_REGNO_REG_SET (pbi->new_set, i);
4709 some_was_live |= needed_regno;
4710 some_was_dead |= ! needed_regno;
4713 #ifdef HAVE_conditional_execution
4714 /* Consider conditional death in deciding that the register needs
4716 if (some_was_live && ! not_dead
4717 /* The stack pointer is never dead. Well, not strictly true,
4718 but it's very difficult to tell from here. Hopefully
4719 combine_stack_adjustments will fix up the most egregious
4721 && regno_first != STACK_POINTER_REGNUM)
4723 for (i = regno_first; i <= regno_last; ++i)
4724 if (! mark_regno_cond_dead (pbi, i, cond))
4729 /* Additional data to record if this is the final pass. */
4730 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
4731 | PROP_DEATH_NOTES | PROP_AUTOINC))
4734 register int blocknum = pbi->bb->index;
4737 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4739 y = pbi->reg_next_use[regno_first];
4741 /* The next use is no longer next, since a store intervenes. */
4742 for (i = regno_first; i <= regno_last; ++i)
4743 pbi->reg_next_use[i] = 0;
4746 if (flags & PROP_REG_INFO)
4748 for (i = regno_first; i <= regno_last; ++i)
4750 /* Count (weighted) references, stores, etc. This counts a
4751 register twice if it is modified, but that is correct. */
4752 REG_N_SETS (i) += 1;
4753 REG_N_REFS (i) += (optimize_size ? 1
4754 : pbi->bb->loop_depth + 1);
4756 /* The insns where a reg is live are normally counted
4757 elsewhere, but we want the count to include the insn
4758 where the reg is set, and the normal counting mechanism
4759 would not count it. */
4760 REG_LIVE_LENGTH (i) += 1;
4763 /* If this is a hard reg, record this function uses the reg. */
4764 if (regno_first < FIRST_PSEUDO_REGISTER)
4766 for (i = regno_first; i <= regno_last; i++)
4767 regs_ever_live[i] = 1;
4771 /* Keep track of which basic blocks each reg appears in. */
4772 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
4773 REG_BASIC_BLOCK (regno_first) = blocknum;
4774 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
4775 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
4779 if (! some_was_dead)
4781 if (flags & PROP_LOG_LINKS)
4783 /* Make a logical link from the next following insn
4784 that uses this register, back to this insn.
4785 The following insns have already been processed.
4787 We don't build a LOG_LINK for hard registers containing
4788 in ASM_OPERANDs. If these registers get replaced,
4789 we might wind up changing the semantics of the insn,
4790 even if reload can make what appear to be valid
4791 assignments later. */
4792 if (y && (BLOCK_NUM (y) == blocknum)
4793 && (regno_first >= FIRST_PSEUDO_REGISTER
4794 || asm_noperands (PATTERN (y)) < 0))
4795 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4800 else if (! some_was_live)
4802 if (flags & PROP_REG_INFO)
4803 REG_N_DEATHS (regno_first) += 1;
4805 if (flags & PROP_DEATH_NOTES)
4807 /* Note that dead stores have already been deleted
4808 when possible. If we get here, we have found a
4809 dead store that cannot be eliminated (because the
4810 same insn does something useful). Indicate this
4811 by marking the reg being set as dying here. */
4813 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4818 if (flags & PROP_DEATH_NOTES)
4820 /* This is a case where we have a multi-word hard register
4821 and some, but not all, of the words of the register are
4822 needed in subsequent insns. Write REG_UNUSED notes
4823 for those parts that were not needed. This case should
4826 for (i = regno_first; i <= regno_last; ++i)
4827 if (! REGNO_REG_SET_P (pbi->reg_live, i))
4829 = alloc_EXPR_LIST (REG_UNUSED,
4830 gen_rtx_REG (reg_raw_mode[i], i),
4836 /* Mark the register as being dead. */
4839 /* The stack pointer is never dead. Well, not strictly true,
4840 but it's very difficult to tell from here. Hopefully
4841 combine_stack_adjustments will fix up the most egregious
4843 && regno_first != STACK_POINTER_REGNUM)
4845 for (i = regno_first; i <= regno_last; ++i)
4846 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
4849 else if (GET_CODE (reg) == REG)
4851 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4852 pbi->reg_next_use[regno_first] = 0;
4855 /* If this is the last pass and this is a SCRATCH, show it will be dying
4856 here and count it. */
4857 else if (GET_CODE (reg) == SCRATCH)
4859 if (flags & PROP_DEATH_NOTES)
4861 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4865 #ifdef HAVE_conditional_execution
4866 /* Mark REGNO conditionally dead.
4867 Return true if the register is now unconditionally dead. */
4870 mark_regno_cond_dead (pbi, regno, cond)
4871 struct propagate_block_info *pbi;
4875 /* If this is a store to a predicate register, the value of the
4876 predicate is changing, we don't know that the predicate as seen
4877 before is the same as that seen after. Flush all dependent
4878 conditions from reg_cond_dead. This will make all such
4879 conditionally live registers unconditionally live. */
4880 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
4881 flush_reg_cond_reg (pbi, regno);
4883 /* If this is an unconditional store, remove any conditional
4884 life that may have existed. */
4885 if (cond == NULL_RTX)
4886 splay_tree_remove (pbi->reg_cond_dead, regno);
4889 splay_tree_node node;
4890 struct reg_cond_life_info *rcli;
4893 /* Otherwise this is a conditional set. Record that fact.
4894 It may have been conditionally used, or there may be a
4895 subsequent set with a complimentary condition. */
4897 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
4900 /* The register was unconditionally live previously.
4901 Record the current condition as the condition under
4902 which it is dead. */
4903 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4904 rcli->condition = alloc_EXPR_LIST (0, cond, NULL_RTX);
4905 splay_tree_insert (pbi->reg_cond_dead, regno,
4906 (splay_tree_value) rcli);
4908 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
4910 /* Not unconditionaly dead. */
4915 /* The register was conditionally live previously.
4916 Add the new condition to the old. */
4917 rcli = (struct reg_cond_life_info *) node->value;
4918 ncond = rcli->condition;
4919 ncond = ior_reg_cond (ncond, cond);
4921 /* If the register is now unconditionally dead,
4922 remove the entry in the splay_tree. */
4923 if (ncond == const1_rtx)
4924 splay_tree_remove (pbi->reg_cond_dead, regno);
4927 rcli->condition = ncond;
4929 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
4931 /* Not unconditionaly dead. */
4940 /* Called from splay_tree_delete for pbi->reg_cond_life. */
4943 free_reg_cond_life_info (value)
4944 splay_tree_value value;
4946 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
4947 free_EXPR_LIST_list (&rcli->condition);
4951 /* Helper function for flush_reg_cond_reg. */
4954 flush_reg_cond_reg_1 (node, data)
4955 splay_tree_node node;
4958 struct reg_cond_life_info *rcli;
4959 int *xdata = (int *) data;
4960 unsigned int regno = xdata[0];
4963 /* Don't need to search if last flushed value was farther on in
4964 the in-order traversal. */
4965 if (xdata[1] >= (int) node->key)
4968 /* Splice out portions of the expression that refer to regno. */
4969 rcli = (struct reg_cond_life_info *) node->value;
4970 c = *(prev = &rcli->condition);
4973 if (regno == REGNO (XEXP (XEXP (c, 0), 0)))
4975 rtx next = XEXP (c, 1);
4976 free_EXPR_LIST_node (c);
4980 c = *(prev = &XEXP (c, 1));
4983 /* If the entire condition is now NULL, signal the node to be removed. */
4984 if (! rcli->condition)
4986 xdata[1] = node->key;
4993 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
4996 flush_reg_cond_reg (pbi, regno)
4997 struct propagate_block_info *pbi;
5004 while (splay_tree_foreach (pbi->reg_cond_dead,
5005 flush_reg_cond_reg_1, pair) == -1)
5006 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
5008 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
5011 /* Logical arithmetic on predicate conditions. IOR, NOT and NAND.
5012 We actually use EXPR_LIST to chain the sub-expressions together
5013 instead of IOR because it's easier to manipulate and we have
5014 the lists.c functions to reuse nodes.
5016 Return a new rtl expression as appropriate. */
5019 ior_reg_cond (old, x)
5022 enum rtx_code x_code;
5026 /* We expect these conditions to be of the form (eq reg 0). */
5027 x_code = GET_CODE (x);
5028 if (GET_RTX_CLASS (x_code) != '<'
5029 || GET_CODE (x_reg = XEXP (x, 0)) != REG
5030 || XEXP (x, 1) != const0_rtx)
5033 /* Search the expression for an existing sub-expression of X_REG. */
5034 for (c = old; c; c = XEXP (c, 1))
5036 rtx y = XEXP (c, 0);
5037 if (REGNO (XEXP (y, 0)) == REGNO (x_reg))
5039 /* If we find X already present in OLD, we need do nothing. */
5040 if (GET_CODE (y) == x_code)
5043 /* If we find X being a compliment of a condition in OLD,
5044 then the entire condition is true. */
5045 if (GET_CODE (y) == reverse_condition (x_code))
5050 /* Otherwise just add to the chain. */
5051 return alloc_EXPR_LIST (0, x, old);
5058 enum rtx_code x_code;
5061 /* We expect these conditions to be of the form (eq reg 0). */
5062 x_code = GET_CODE (x);
5063 if (GET_RTX_CLASS (x_code) != '<'
5064 || GET_CODE (x_reg = XEXP (x, 0)) != REG
5065 || XEXP (x, 1) != const0_rtx)
5068 return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code),
5069 VOIDmode, x_reg, const0_rtx),
5074 nand_reg_cond (old, x)
5077 enum rtx_code x_code;
5081 /* We expect these conditions to be of the form (eq reg 0). */
5082 x_code = GET_CODE (x);
5083 if (GET_RTX_CLASS (x_code) != '<'
5084 || GET_CODE (x_reg = XEXP (x, 0)) != REG
5085 || XEXP (x, 1) != const0_rtx)
5088 /* Search the expression for an existing sub-expression of X_REG. */
5090 for (c = *(prev = &old); c; c = *(prev = &XEXP (c, 1)))
5092 rtx y = XEXP (c, 0);
5093 if (REGNO (XEXP (y, 0)) == REGNO (x_reg))
5095 /* If we find X already present in OLD, then we need to
5097 if (GET_CODE (y) == x_code)
5099 *prev = XEXP (c, 1);
5100 free_EXPR_LIST_node (c);
5101 return old ? old : const0_rtx;
5104 /* If we find X being a compliment of a condition in OLD,
5105 then we need do nothing. */
5106 if (GET_CODE (y) == reverse_condition (x_code))
5111 /* Otherwise, by implication, the register in question is now live for
5112 the inverse of the condition X. */
5113 return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code),
5114 VOIDmode, x_reg, const0_rtx),
5117 #endif /* HAVE_conditional_execution */
5121 /* Try to substitute the auto-inc expression INC as the address inside
5122 MEM which occurs in INSN. Currently, the address of MEM is an expression
5123 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
5124 that has a single set whose source is a PLUS of INCR_REG and something
5128 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
5129 struct propagate_block_info *pbi;
5130 rtx inc, insn, mem, incr, incr_reg;
5132 int regno = REGNO (incr_reg);
5133 rtx set = single_set (incr);
5134 rtx q = SET_DEST (set);
5135 rtx y = SET_SRC (set);
5136 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
5138 /* Make sure this reg appears only once in this insn. */
5139 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
5142 if (dead_or_set_p (incr, incr_reg)
5143 /* Mustn't autoinc an eliminable register. */
5144 && (regno >= FIRST_PSEUDO_REGISTER
5145 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
5147 /* This is the simple case. Try to make the auto-inc. If
5148 we can't, we are done. Otherwise, we will do any
5149 needed updates below. */
5150 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
5153 else if (GET_CODE (q) == REG
5154 /* PREV_INSN used here to check the semi-open interval
5156 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5157 /* We must also check for sets of q as q may be
5158 a call clobbered hard register and there may
5159 be a call between PREV_INSN (insn) and incr. */
5160 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5162 /* We have *p followed sometime later by q = p+size.
5163 Both p and q must be live afterward,
5164 and q is not used between INSN and its assignment.
5165 Change it to q = p, ...*q..., q = q+size.
5166 Then fall into the usual case. */
5170 emit_move_insn (q, incr_reg);
5171 insns = get_insns ();
5174 if (basic_block_for_insn)
5175 for (temp = insns; temp; temp = NEXT_INSN (temp))
5176 set_block_for_insn (temp, pbi->bb);
5178 /* If we can't make the auto-inc, or can't make the
5179 replacement into Y, exit. There's no point in making
5180 the change below if we can't do the auto-inc and doing
5181 so is not correct in the pre-inc case. */
5184 validate_change (insn, &XEXP (mem, 0), inc, 1);
5185 validate_change (incr, &XEXP (y, opnum), q, 1);
5186 if (! apply_change_group ())
5189 /* We now know we'll be doing this change, so emit the
5190 new insn(s) and do the updates. */
5191 emit_insns_before (insns, insn);
5193 if (pbi->bb->head == insn)
5194 pbi->bb->head = insns;
5196 /* INCR will become a NOTE and INSN won't contain a
5197 use of INCR_REG. If a use of INCR_REG was just placed in
5198 the insn before INSN, make that the next use.
5199 Otherwise, invalidate it. */
5200 if (GET_CODE (PREV_INSN (insn)) == INSN
5201 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
5202 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
5203 pbi->reg_next_use[regno] = PREV_INSN (insn);
5205 pbi->reg_next_use[regno] = 0;
5210 /* REGNO is now used in INCR which is below INSN, but
5211 it previously wasn't live here. If we don't mark
5212 it as live, we'll put a REG_DEAD note for it
5213 on this insn, which is incorrect. */
5214 SET_REGNO_REG_SET (pbi->reg_live, regno);
5216 /* If there are any calls between INSN and INCR, show
5217 that REGNO now crosses them. */
5218 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
5219 if (GET_CODE (temp) == CALL_INSN)
5220 REG_N_CALLS_CROSSED (regno)++;
5225 /* If we haven't returned, it means we were able to make the
5226 auto-inc, so update the status. First, record that this insn
5227 has an implicit side effect. */
5229 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
5231 /* Modify the old increment-insn to simply copy
5232 the already-incremented value of our register. */
5233 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
5236 /* If that makes it a no-op (copying the register into itself) delete
5237 it so it won't appear to be a "use" and a "set" of this
5239 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
5241 /* If the original source was dead, it's dead now. */
5244 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
5246 remove_note (incr, note);
5247 if (XEXP (note, 0) != incr_reg)
5248 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
5251 PUT_CODE (incr, NOTE);
5252 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
5253 NOTE_SOURCE_FILE (incr) = 0;
5256 if (regno >= FIRST_PSEUDO_REGISTER)
5258 /* Count an extra reference to the reg. When a reg is
5259 incremented, spilling it is worse, so we want to make
5260 that less likely. */
5261 REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5263 /* Count the increment as a setting of the register,
5264 even though it isn't a SET in rtl. */
5265 REG_N_SETS (regno)++;
5269 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
5273 find_auto_inc (pbi, x, insn)
5274 struct propagate_block_info *pbi;
5278 rtx addr = XEXP (x, 0);
5279 HOST_WIDE_INT offset = 0;
5280 rtx set, y, incr, inc_val;
5282 int size = GET_MODE_SIZE (GET_MODE (x));
5284 if (GET_CODE (insn) == JUMP_INSN)
5287 /* Here we detect use of an index register which might be good for
5288 postincrement, postdecrement, preincrement, or predecrement. */
5290 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
5291 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
5293 if (GET_CODE (addr) != REG)
5296 regno = REGNO (addr);
5298 /* Is the next use an increment that might make auto-increment? */
5299 incr = pbi->reg_next_use[regno];
5300 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
5302 set = single_set (incr);
5303 if (set == 0 || GET_CODE (set) != SET)
5307 if (GET_CODE (y) != PLUS)
5310 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
5311 inc_val = XEXP (y, 1);
5312 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
5313 inc_val = XEXP (y, 0);
5317 if (GET_CODE (inc_val) == CONST_INT)
5319 if (HAVE_POST_INCREMENT
5320 && (INTVAL (inc_val) == size && offset == 0))
5321 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
5323 else if (HAVE_POST_DECREMENT
5324 && (INTVAL (inc_val) == -size && offset == 0))
5325 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
5327 else if (HAVE_PRE_INCREMENT
5328 && (INTVAL (inc_val) == size && offset == size))
5329 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
5331 else if (HAVE_PRE_DECREMENT
5332 && (INTVAL (inc_val) == -size && offset == -size))
5333 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
5335 else if (HAVE_POST_MODIFY_DISP && offset == 0)
5336 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5337 gen_rtx_PLUS (Pmode,
5340 insn, x, incr, addr);
5342 else if (GET_CODE (inc_val) == REG
5343 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
5347 if (HAVE_POST_MODIFY_REG && offset == 0)
5348 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5349 gen_rtx_PLUS (Pmode,
5352 insn, x, incr, addr);
5356 #endif /* AUTO_INC_DEC */
5359 mark_used_reg (pbi, reg, cond, insn)
5360 struct propagate_block_info *pbi;
5362 rtx cond ATTRIBUTE_UNUSED;
5365 int regno = REGNO (reg);
5366 int some_was_live = REGNO_REG_SET_P (pbi->reg_live, regno);
5367 int some_was_dead = ! some_was_live;
5371 /* A hard reg in a wide mode may really be multiple registers.
5372 If so, mark all of them just like the first. */
5373 if (regno < FIRST_PSEUDO_REGISTER)
5375 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5378 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, regno + n);
5379 some_was_live |= needed_regno;
5380 some_was_dead |= ! needed_regno;
5384 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5386 /* Record where each reg is used, so when the reg is set we know
5387 the next insn that uses it. */
5388 pbi->reg_next_use[regno] = insn;
5391 if (pbi->flags & PROP_REG_INFO)
5393 if (regno < FIRST_PSEUDO_REGISTER)
5395 /* If this is a register we are going to try to eliminate,
5396 don't mark it live here. If we are successful in
5397 eliminating it, it need not be live unless it is used for
5398 pseudos, in which case it will have been set live when it
5399 was allocated to the pseudos. If the register will not
5400 be eliminated, reload will set it live at that point.
5402 Otherwise, record that this function uses this register. */
5403 /* ??? The PPC backend tries to "eliminate" on the pic
5404 register to itself. This should be fixed. In the mean
5405 time, hack around it. */
5407 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno)
5408 && (regno == FRAME_POINTER_REGNUM
5409 || regno == ARG_POINTER_REGNUM)))
5411 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5413 regs_ever_live[regno + --n] = 1;
5419 /* Keep track of which basic block each reg appears in. */
5421 register int blocknum = pbi->bb->index;
5422 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
5423 REG_BASIC_BLOCK (regno) = blocknum;
5424 else if (REG_BASIC_BLOCK (regno) != blocknum)
5425 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
5427 /* Count (weighted) number of uses of each reg. */
5428 REG_N_REFS (regno) += (optimize_size ? 1
5429 : pbi->bb->loop_depth + 1);
5433 /* Find out if any of the register was set this insn. */
5434 some_not_set = ! REGNO_REG_SET_P (pbi->new_set, regno);
5435 if (regno < FIRST_PSEUDO_REGISTER)
5437 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5439 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, regno + n);
5442 /* Record and count the insns in which a reg dies. If it is used in
5443 this insn and was dead below the insn then it dies in this insn.
5444 If it was set in this insn, we do not make a REG_DEAD note;
5445 likewise if we already made such a note. */
5446 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
5450 /* Check for the case where the register dying partially
5451 overlaps the register set by this insn. */
5452 if (regno < FIRST_PSEUDO_REGISTER
5453 && HARD_REGNO_NREGS (regno, GET_MODE (reg)) > 1)
5455 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5457 some_was_live |= REGNO_REG_SET_P (pbi->new_set, regno + n);
5460 /* If none of the words in X is needed, make a REG_DEAD note.
5461 Otherwise, we must make partial REG_DEAD notes. */
5462 if (! some_was_live)
5464 if ((pbi->flags & PROP_DEATH_NOTES)
5465 && ! find_regno_note (insn, REG_DEAD, regno))
5467 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
5469 if (pbi->flags & PROP_REG_INFO)
5470 REG_N_DEATHS (regno)++;
5474 /* Don't make a REG_DEAD note for a part of a register
5475 that is set in the insn. */
5477 n = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
5478 for (; n >= regno; n--)
5479 if (! REGNO_REG_SET_P (pbi->reg_live, n)
5480 && ! dead_or_set_regno_p (insn, n))
5482 = alloc_EXPR_LIST (REG_DEAD,
5483 gen_rtx_REG (reg_raw_mode[n], n),
5488 SET_REGNO_REG_SET (pbi->reg_live, regno);
5489 if (regno < FIRST_PSEUDO_REGISTER)
5491 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5493 SET_REGNO_REG_SET (pbi->reg_live, regno + n);
5496 #ifdef HAVE_conditional_execution
5497 /* If this is a conditional use, record that fact. If it is later
5498 conditionally set, we'll know to kill the register. */
5499 if (cond != NULL_RTX)
5501 splay_tree_node node;
5502 struct reg_cond_life_info *rcli;
5507 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5510 /* The register was unconditionally live previously.
5511 No need to do anything. */
5515 /* The register was conditionally live previously.
5516 Subtract the new life cond from the old death cond. */
5517 rcli = (struct reg_cond_life_info *) node->value;
5518 ncond = rcli->condition;
5519 ncond = nand_reg_cond (ncond, cond);
5521 /* If the register is now unconditionally live, remove the
5522 entry in the splay_tree. */
5523 if (ncond == const0_rtx)
5525 rcli->condition = NULL_RTX;
5526 splay_tree_remove (pbi->reg_cond_dead, regno);
5530 rcli->condition = ncond;
5531 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5537 /* The register was not previously live at all. Record
5538 the condition under which it is still dead. */
5539 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5540 rcli->condition = not_reg_cond (cond);
5541 splay_tree_insert (pbi->reg_cond_dead, regno,
5542 (splay_tree_value) rcli);
5544 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5547 else if (some_was_live)
5549 splay_tree_node node;
5550 struct reg_cond_life_info *rcli;
5552 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5555 /* The register was conditionally live previously, but is now
5556 unconditionally so. Remove it from the conditionally dead
5557 list, so that a conditional set won't cause us to think
5559 rcli = (struct reg_cond_life_info *) node->value;
5560 rcli->condition = NULL_RTX;
5561 splay_tree_remove (pbi->reg_cond_dead, regno);
5568 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5569 This is done assuming the registers needed from X are those that
5570 have 1-bits in PBI->REG_LIVE.
5572 INSN is the containing instruction. If INSN is dead, this function
5576 mark_used_regs (pbi, x, cond, insn)
5577 struct propagate_block_info *pbi;
5580 register RTX_CODE code;
5582 int flags = pbi->flags;
5585 code = GET_CODE (x);
5605 /* If we are clobbering a MEM, mark any registers inside the address
5607 if (GET_CODE (XEXP (x, 0)) == MEM)
5608 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
5612 /* Don't bother watching stores to mems if this is not the
5613 final pass. We'll not be deleting dead stores this round. */
5614 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5616 /* Invalidate the data for the last MEM stored, but only if MEM is
5617 something that can be stored into. */
5618 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
5619 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
5620 /* Needn't clear the memory set list. */
5624 rtx temp = pbi->mem_set_list;
5625 rtx prev = NULL_RTX;
5630 next = XEXP (temp, 1);
5631 if (anti_dependence (XEXP (temp, 0), x))
5633 /* Splice temp out of the list. */
5635 XEXP (prev, 1) = next;
5637 pbi->mem_set_list = next;
5638 free_EXPR_LIST_node (temp);
5646 /* If the memory reference had embedded side effects (autoincrement
5647 address modes. Then we may need to kill some entries on the
5650 invalidate_mems_from_autoinc (pbi, insn);
5654 if (flags & PROP_AUTOINC)
5655 find_auto_inc (pbi, x, insn);
5660 #ifdef CLASS_CANNOT_CHANGE_MODE
5661 if (GET_CODE (SUBREG_REG (x)) == REG
5662 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
5663 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
5664 GET_MODE (SUBREG_REG (x))))
5665 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
5668 /* While we're here, optimize this case. */
5670 if (GET_CODE (x) != REG)
5675 /* See a register other than being set => mark it as needed. */
5676 mark_used_reg (pbi, x, cond, insn);
5681 register rtx testreg = SET_DEST (x);
5684 /* If storing into MEM, don't show it as being used. But do
5685 show the address as being used. */
5686 if (GET_CODE (testreg) == MEM)
5689 if (flags & PROP_AUTOINC)
5690 find_auto_inc (pbi, testreg, insn);
5692 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
5693 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5697 /* Storing in STRICT_LOW_PART is like storing in a reg
5698 in that this SET might be dead, so ignore it in TESTREG.
5699 but in some other ways it is like using the reg.
5701 Storing in a SUBREG or a bit field is like storing the entire
5702 register in that if the register's value is not used
5703 then this SET is not needed. */
5704 while (GET_CODE (testreg) == STRICT_LOW_PART
5705 || GET_CODE (testreg) == ZERO_EXTRACT
5706 || GET_CODE (testreg) == SIGN_EXTRACT
5707 || GET_CODE (testreg) == SUBREG)
5709 #ifdef CLASS_CANNOT_CHANGE_MODE
5710 if (GET_CODE (testreg) == SUBREG
5711 && GET_CODE (SUBREG_REG (testreg)) == REG
5712 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
5713 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
5714 GET_MODE (testreg)))
5715 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
5718 /* Modifying a single register in an alternate mode
5719 does not use any of the old value. But these other
5720 ways of storing in a register do use the old value. */
5721 if (GET_CODE (testreg) == SUBREG
5722 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5727 testreg = XEXP (testreg, 0);
5730 /* If this is a store into a register, recursively scan the
5731 value being stored. */
5733 if ((GET_CODE (testreg) == PARALLEL
5734 && GET_MODE (testreg) == BLKmode)
5735 || (GET_CODE (testreg) == REG
5736 && (regno = REGNO (testreg),
5737 ! (regno == FRAME_POINTER_REGNUM
5738 && (! reload_completed || frame_pointer_needed)))
5739 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5740 && ! (regno == HARD_FRAME_POINTER_REGNUM
5741 && (! reload_completed || frame_pointer_needed))
5743 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5744 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5749 mark_used_regs (pbi, SET_DEST (x), cond, insn);
5750 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5757 case UNSPEC_VOLATILE:
5761 /* Traditional and volatile asm instructions must be considered to use
5762 and clobber all hard registers, all pseudo-registers and all of
5763 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
5765 Consider for instance a volatile asm that changes the fpu rounding
5766 mode. An insn should not be moved across this even if it only uses
5767 pseudo-regs because it might give an incorrectly rounded result.
5769 ?!? Unfortunately, marking all hard registers as live causes massive
5770 problems for the register allocator and marking all pseudos as live
5771 creates mountains of uninitialized variable warnings.
5773 So for now, just clear the memory set list and mark any regs
5774 we can find in ASM_OPERANDS as used. */
5775 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
5776 free_EXPR_LIST_list (&pbi->mem_set_list);
5778 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
5779 We can not just fall through here since then we would be confused
5780 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
5781 traditional asms unlike their normal usage. */
5782 if (code == ASM_OPERANDS)
5786 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
5787 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
5793 if (cond != NULL_RTX)
5796 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
5798 cond = COND_EXEC_TEST (x);
5799 x = COND_EXEC_CODE (x);
5803 /* We _do_not_ want to scan operands of phi nodes. Operands of
5804 a phi function are evaluated only when control reaches this
5805 block along a particular edge. Therefore, regs that appear
5806 as arguments to phi should not be added to the global live at
5814 /* Recursively scan the operands of this expression. */
5817 register const char *fmt = GET_RTX_FORMAT (code);
5820 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5824 /* Tail recursive case: save a function call level. */
5830 mark_used_regs (pbi, XEXP (x, i), cond, insn);
5832 else if (fmt[i] == 'E')
5835 for (j = 0; j < XVECLEN (x, i); j++)
5836 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
5845 try_pre_increment_1 (pbi, insn)
5846 struct propagate_block_info *pbi;
5849 /* Find the next use of this reg. If in same basic block,
5850 make it do pre-increment or pre-decrement if appropriate. */
5851 rtx x = single_set (insn);
5852 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
5853 * INTVAL (XEXP (SET_SRC (x), 1)));
5854 int regno = REGNO (SET_DEST (x));
5855 rtx y = pbi->reg_next_use[regno];
5857 && SET_DEST (x) != stack_pointer_rtx
5858 && BLOCK_NUM (y) == BLOCK_NUM (insn)
5859 /* Don't do this if the reg dies, or gets set in y; a standard addressing
5860 mode would be better. */
5861 && ! dead_or_set_p (y, SET_DEST (x))
5862 && try_pre_increment (y, SET_DEST (x), amount))
5864 /* We have found a suitable auto-increment and already changed
5865 insn Y to do it. So flush this increment instruction. */
5866 propagate_block_delete_insn (pbi->bb, insn);
5868 /* Count a reference to this reg for the increment insn we are
5869 deleting. When a reg is incremented, spilling it is worse,
5870 so we want to make that less likely. */
5871 if (regno >= FIRST_PSEUDO_REGISTER)
5873 REG_N_REFS (regno) += (optimize_size ? 1
5874 : pbi->bb->loop_depth + 1);
5875 REG_N_SETS (regno)++;
5878 /* Flush any remembered memories depending on the value of
5879 the incremented register. */
5880 invalidate_mems_from_set (pbi, SET_DEST (x));
5887 /* Try to change INSN so that it does pre-increment or pre-decrement
5888 addressing on register REG in order to add AMOUNT to REG.
5889 AMOUNT is negative for pre-decrement.
5890 Returns 1 if the change could be made.
5891 This checks all about the validity of the result of modifying INSN. */
5894 try_pre_increment (insn, reg, amount)
5896 HOST_WIDE_INT amount;
5900 /* Nonzero if we can try to make a pre-increment or pre-decrement.
5901 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
5903 /* Nonzero if we can try to make a post-increment or post-decrement.
5904 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
5905 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
5906 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
5909 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
5912 /* From the sign of increment, see which possibilities are conceivable
5913 on this target machine. */
5914 if (HAVE_PRE_INCREMENT && amount > 0)
5916 if (HAVE_POST_INCREMENT && amount > 0)
5919 if (HAVE_PRE_DECREMENT && amount < 0)
5921 if (HAVE_POST_DECREMENT && amount < 0)
5924 if (! (pre_ok || post_ok))
5927 /* It is not safe to add a side effect to a jump insn
5928 because if the incremented register is spilled and must be reloaded
5929 there would be no way to store the incremented value back in memory. */
5931 if (GET_CODE (insn) == JUMP_INSN)
5936 use = find_use_as_address (PATTERN (insn), reg, 0);
5937 if (post_ok && (use == 0 || use == (rtx) 1))
5939 use = find_use_as_address (PATTERN (insn), reg, -amount);
5943 if (use == 0 || use == (rtx) 1)
5946 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
5949 /* See if this combination of instruction and addressing mode exists. */
5950 if (! validate_change (insn, &XEXP (use, 0),
5951 gen_rtx_fmt_e (amount > 0
5952 ? (do_post ? POST_INC : PRE_INC)
5953 : (do_post ? POST_DEC : PRE_DEC),
5957 /* Record that this insn now has an implicit side effect on X. */
5958 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
5962 #endif /* AUTO_INC_DEC */
5964 /* Find the place in the rtx X where REG is used as a memory address.
5965 Return the MEM rtx that so uses it.
5966 If PLUSCONST is nonzero, search instead for a memory address equivalent to
5967 (plus REG (const_int PLUSCONST)).
5969 If such an address does not appear, return 0.
5970 If REG appears more than once, or is used other than in such an address,
5974 find_use_as_address (x, reg, plusconst)
5977 HOST_WIDE_INT plusconst;
5979 enum rtx_code code = GET_CODE (x);
5980 const char *fmt = GET_RTX_FORMAT (code);
5982 register rtx value = 0;
5985 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
5988 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
5989 && XEXP (XEXP (x, 0), 0) == reg
5990 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5991 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
5994 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
5996 /* If REG occurs inside a MEM used in a bit-field reference,
5997 that is unacceptable. */
5998 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
5999 return (rtx) (HOST_WIDE_INT) 1;
6003 return (rtx) (HOST_WIDE_INT) 1;
6005 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6009 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
6013 return (rtx) (HOST_WIDE_INT) 1;
6015 else if (fmt[i] == 'E')
6018 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6020 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
6024 return (rtx) (HOST_WIDE_INT) 1;
6032 /* Write information about registers and basic blocks into FILE.
6033 This is part of making a debugging dump. */
6036 dump_regset (r, outf)
6043 fputs (" (nil)", outf);
6047 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
6049 fprintf (outf, " %d", i);
6050 if (i < FIRST_PSEUDO_REGISTER)
6051 fprintf (outf, " [%s]",
6060 dump_regset (r, stderr);
6061 putc ('\n', stderr);
6065 dump_flow_info (file)
6069 static const char * const reg_class_names[] = REG_CLASS_NAMES;
6071 fprintf (file, "%d registers.\n", max_regno);
6072 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
6075 enum reg_class class, altclass;
6076 fprintf (file, "\nRegister %d used %d times across %d insns",
6077 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
6078 if (REG_BASIC_BLOCK (i) >= 0)
6079 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
6081 fprintf (file, "; set %d time%s", REG_N_SETS (i),
6082 (REG_N_SETS (i) == 1) ? "" : "s");
6083 if (REG_USERVAR_P (regno_reg_rtx[i]))
6084 fprintf (file, "; user var");
6085 if (REG_N_DEATHS (i) != 1)
6086 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
6087 if (REG_N_CALLS_CROSSED (i) == 1)
6088 fprintf (file, "; crosses 1 call");
6089 else if (REG_N_CALLS_CROSSED (i))
6090 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
6091 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
6092 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
6093 class = reg_preferred_class (i);
6094 altclass = reg_alternate_class (i);
6095 if (class != GENERAL_REGS || altclass != ALL_REGS)
6097 if (altclass == ALL_REGS || class == ALL_REGS)
6098 fprintf (file, "; pref %s", reg_class_names[(int) class]);
6099 else if (altclass == NO_REGS)
6100 fprintf (file, "; %s or none", reg_class_names[(int) class]);
6102 fprintf (file, "; pref %s, else %s",
6103 reg_class_names[(int) class],
6104 reg_class_names[(int) altclass]);
6106 if (REG_POINTER (regno_reg_rtx[i]))
6107 fprintf (file, "; pointer");
6108 fprintf (file, ".\n");
6111 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
6112 for (i = 0; i < n_basic_blocks; i++)
6114 register basic_block bb = BASIC_BLOCK (i);
6117 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
6118 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count);
6120 fprintf (file, "Predecessors: ");
6121 for (e = bb->pred; e; e = e->pred_next)
6122 dump_edge_info (file, e, 0);
6124 fprintf (file, "\nSuccessors: ");
6125 for (e = bb->succ; e; e = e->succ_next)
6126 dump_edge_info (file, e, 1);
6128 fprintf (file, "\nRegisters live at start:");
6129 dump_regset (bb->global_live_at_start, file);
6131 fprintf (file, "\nRegisters live at end:");
6132 dump_regset (bb->global_live_at_end, file);
6143 dump_flow_info (stderr);
6147 dump_edge_info (file, e, do_succ)
6152 basic_block side = (do_succ ? e->dest : e->src);
6154 if (side == ENTRY_BLOCK_PTR)
6155 fputs (" ENTRY", file);
6156 else if (side == EXIT_BLOCK_PTR)
6157 fputs (" EXIT", file);
6159 fprintf (file, " %d", side->index);
6162 fprintf (file, " count:%d", e->count);
6166 static const char * const bitnames[] = {
6167 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6170 int i, flags = e->flags;
6174 for (i = 0; flags; i++)
6175 if (flags & (1 << i))
6181 if (i < (int) ARRAY_SIZE (bitnames))
6182 fputs (bitnames[i], file);
6184 fprintf (file, "%d", i);
6191 /* Print out one basic block with live information at start and end. */
6202 fprintf (outf, ";; Basic block %d, loop depth %d, count %d",
6203 bb->index, bb->loop_depth, bb->count);
6204 if (bb->eh_beg != -1 || bb->eh_end != -1)
6205 fprintf (outf, ", eh regions %d/%d", bb->eh_beg, bb->eh_end);
6208 fputs (";; Predecessors: ", outf);
6209 for (e = bb->pred; e; e = e->pred_next)
6210 dump_edge_info (outf, e, 0);
6213 fputs (";; Registers live at start:", outf);
6214 dump_regset (bb->global_live_at_start, outf);
6217 for (insn = bb->head, last = NEXT_INSN (bb->end);
6219 insn = NEXT_INSN (insn))
6220 print_rtl_single (outf, insn);
6222 fputs (";; Registers live at end:", outf);
6223 dump_regset (bb->global_live_at_end, outf);
6226 fputs (";; Successors: ", outf);
6227 for (e = bb->succ; e; e = e->succ_next)
6228 dump_edge_info (outf, e, 1);
6236 dump_bb (bb, stderr);
6243 dump_bb (BASIC_BLOCK (n), stderr);
6246 /* Like print_rtl, but also print out live information for the start of each
6250 print_rtl_with_bb (outf, rtx_first)
6254 register rtx tmp_rtx;
6257 fprintf (outf, "(nil)\n");
6261 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
6262 int max_uid = get_max_uid ();
6263 basic_block *start = (basic_block *)
6264 xcalloc (max_uid, sizeof (basic_block));
6265 basic_block *end = (basic_block *)
6266 xcalloc (max_uid, sizeof (basic_block));
6267 enum bb_state *in_bb_p = (enum bb_state *)
6268 xcalloc (max_uid, sizeof (enum bb_state));
6270 for (i = n_basic_blocks - 1; i >= 0; i--)
6272 basic_block bb = BASIC_BLOCK (i);
6275 start[INSN_UID (bb->head)] = bb;
6276 end[INSN_UID (bb->end)] = bb;
6277 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
6279 enum bb_state state = IN_MULTIPLE_BB;
6280 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
6282 in_bb_p[INSN_UID (x)] = state;
6289 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
6294 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
6296 fprintf (outf, ";; Start of basic block %d, registers live:",
6298 dump_regset (bb->global_live_at_start, outf);
6302 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
6303 && GET_CODE (tmp_rtx) != NOTE
6304 && GET_CODE (tmp_rtx) != BARRIER)
6305 fprintf (outf, ";; Insn is not within a basic block\n");
6306 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
6307 fprintf (outf, ";; Insn is in multiple basic blocks\n");
6309 did_output = print_rtl_single (outf, tmp_rtx);
6311 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
6313 fprintf (outf, ";; End of basic block %d, registers live:\n",
6315 dump_regset (bb->global_live_at_end, outf);
6328 if (current_function_epilogue_delay_list != 0)
6330 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
6331 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
6332 tmp_rtx = XEXP (tmp_rtx, 1))
6333 print_rtl_single (outf, XEXP (tmp_rtx, 0));
6337 /* Dump the rtl into the current debugging dump file, then abort. */
6339 print_rtl_and_abort ()
6343 print_rtl_with_bb (rtl_dump_file, get_insns ());
6344 fclose (rtl_dump_file);
6349 /* Recompute register set/reference counts immediately prior to register
6352 This avoids problems with set/reference counts changing to/from values
6353 which have special meanings to the register allocators.
6355 Additionally, the reference counts are the primary component used by the
6356 register allocators to prioritize pseudos for allocation to hard regs.
6357 More accurate reference counts generally lead to better register allocation.
6359 F is the first insn to be scanned.
6361 LOOP_STEP denotes how much loop_depth should be incremented per
6362 loop nesting level in order to increase the ref count more for
6363 references in a loop.
6365 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6366 possibly other information which is used by the register allocators. */
6369 recompute_reg_usage (f, loop_step)
6370 rtx f ATTRIBUTE_UNUSED;
6371 int loop_step ATTRIBUTE_UNUSED;
6373 allocate_reg_life_data ();
6374 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
6377 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6378 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6379 of the number of registers that died. */
6382 count_or_remove_death_notes (blocks, kill)
6388 for (i = n_basic_blocks - 1; i >= 0; --i)
6393 if (blocks && ! TEST_BIT (blocks, i))
6396 bb = BASIC_BLOCK (i);
6398 for (insn = bb->head;; insn = NEXT_INSN (insn))
6402 rtx *pprev = ®_NOTES (insn);
6407 switch (REG_NOTE_KIND (link))
6410 if (GET_CODE (XEXP (link, 0)) == REG)
6412 rtx reg = XEXP (link, 0);
6415 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
6418 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
6426 rtx next = XEXP (link, 1);
6427 free_EXPR_LIST_node (link);
6428 *pprev = link = next;
6434 pprev = &XEXP (link, 1);
6441 if (insn == bb->end)
6450 /* Update insns block within BB. */
6453 update_bb_for_insn (bb)
6458 if (! basic_block_for_insn)
6461 for (insn = bb->head; ; insn = NEXT_INSN (insn))
6463 set_block_for_insn (insn, bb);
6465 if (insn == bb->end)
6471 /* Record INSN's block as BB. */
6474 set_block_for_insn (insn, bb)
6478 size_t uid = INSN_UID (insn);
6479 if (uid >= basic_block_for_insn->num_elements)
6483 /* Add one-eighth the size so we don't keep calling xrealloc. */
6484 new_size = uid + (uid + 7) / 8;
6486 VARRAY_GROW (basic_block_for_insn, new_size);
6488 VARRAY_BB (basic_block_for_insn, uid) = bb;
6491 /* Record INSN's block number as BB. */
6492 /* ??? This has got to go. */
6495 set_block_num (insn, bb)
6499 set_block_for_insn (insn, BASIC_BLOCK (bb));
6502 /* Verify the CFG consistency. This function check some CFG invariants and
6503 aborts when something is wrong. Hope that this function will help to
6504 convert many optimization passes to preserve CFG consistent.
6506 Currently it does following checks:
6508 - test head/end pointers
6509 - overlapping of basic blocks
6510 - edge list corectness
6511 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6512 - tails of basic blocks (ensure that boundary is necesary)
6513 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6514 and NOTE_INSN_BASIC_BLOCK
6515 - check that all insns are in the basic blocks
6516 (except the switch handling code, barriers and notes)
6517 - check that all returns are followed by barriers
6519 In future it can be extended check a lot of other stuff as well
6520 (reachability of basic blocks, life information, etc. etc.). */
6525 const int max_uid = get_max_uid ();
6526 const rtx rtx_first = get_insns ();
6527 rtx last_head = get_last_insn ();
6528 basic_block *bb_info;
6530 int i, last_bb_num_seen, num_bb_notes, err = 0;
6532 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
6534 for (i = n_basic_blocks - 1; i >= 0; i--)
6536 basic_block bb = BASIC_BLOCK (i);
6537 rtx head = bb->head;
6540 /* Verify the end of the basic block is in the INSN chain. */
6541 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
6546 error ("End insn %d for block %d not found in the insn stream.",
6547 INSN_UID (end), bb->index);
6551 /* Work backwards from the end to the head of the basic block
6552 to verify the head is in the RTL chain. */
6553 for (; x != NULL_RTX; x = PREV_INSN (x))
6555 /* While walking over the insn chain, verify insns appear
6556 in only one basic block and initialize the BB_INFO array
6557 used by other passes. */
6558 if (bb_info[INSN_UID (x)] != NULL)
6560 error ("Insn %d is in multiple basic blocks (%d and %d)",
6561 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
6564 bb_info[INSN_UID (x)] = bb;
6571 error ("Head insn %d for block %d not found in the insn stream.",
6572 INSN_UID (head), bb->index);
6579 /* Now check the basic blocks (boundaries etc.) */
6580 for (i = n_basic_blocks - 1; i >= 0; i--)
6582 basic_block bb = BASIC_BLOCK (i);
6583 /* Check corectness of edge lists */
6592 "verify_flow_info: Basic block %d succ edge is corrupted\n",
6594 fprintf (stderr, "Predecessor: ");
6595 dump_edge_info (stderr, e, 0);
6596 fprintf (stderr, "\nSuccessor: ");
6597 dump_edge_info (stderr, e, 1);
6601 if (e->dest != EXIT_BLOCK_PTR)
6603 edge e2 = e->dest->pred;
6604 while (e2 && e2 != e)
6608 error ("Basic block %i edge lists are corrupted", bb->index);
6620 error ("Basic block %d pred edge is corrupted", bb->index);
6621 fputs ("Predecessor: ", stderr);
6622 dump_edge_info (stderr, e, 0);
6623 fputs ("\nSuccessor: ", stderr);
6624 dump_edge_info (stderr, e, 1);
6625 fputc ('\n', stderr);
6628 if (e->src != ENTRY_BLOCK_PTR)
6630 edge e2 = e->src->succ;
6631 while (e2 && e2 != e)
6635 error ("Basic block %i edge lists are corrupted", bb->index);
6642 /* OK pointers are correct. Now check the header of basic
6643 block. It ought to contain optional CODE_LABEL followed
6644 by NOTE_BASIC_BLOCK. */
6646 if (GET_CODE (x) == CODE_LABEL)
6650 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6656 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
6658 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6665 /* Do checks for empty blocks here */
6672 if (NOTE_INSN_BASIC_BLOCK_P (x))
6674 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6675 INSN_UID (x), bb->index);
6682 if (GET_CODE (x) == JUMP_INSN
6683 || GET_CODE (x) == CODE_LABEL
6684 || GET_CODE (x) == BARRIER)
6686 error ("In basic block %d:", bb->index);
6687 fatal_insn ("Flow control insn inside a basic block", x);
6695 last_bb_num_seen = -1;
6700 if (NOTE_INSN_BASIC_BLOCK_P (x))
6702 basic_block bb = NOTE_BASIC_BLOCK (x);
6704 if (bb->index != last_bb_num_seen + 1)
6705 fatal ("Basic blocks not numbered consecutively");
6706 last_bb_num_seen = bb->index;
6709 if (!bb_info[INSN_UID (x)])
6711 switch (GET_CODE (x))
6718 /* An addr_vec is placed outside any block block. */
6720 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
6721 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
6722 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
6727 /* But in any case, non-deletable labels can appear anywhere. */
6731 fatal_insn ("Insn outside basic block", x);
6736 && GET_CODE (x) == JUMP_INSN
6737 && returnjump_p (x) && ! condjump_p (x)
6738 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
6739 fatal_insn ("Return not followed by barrier", x);
6744 if (num_bb_notes != n_basic_blocks)
6745 fatal ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
6746 num_bb_notes, n_basic_blocks);
6755 /* Functions to access an edge list with a vector representation.
6756 Enough data is kept such that given an index number, the
6757 pred and succ that edge represents can be determined, or
6758 given a pred and a succ, its index number can be returned.
6759 This allows algorithms which consume a lot of memory to
6760 represent the normally full matrix of edge (pred,succ) with a
6761 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
6762 wasted space in the client code due to sparse flow graphs. */
6764 /* This functions initializes the edge list. Basically the entire
6765 flowgraph is processed, and all edges are assigned a number,
6766 and the data structure is filled in. */
6771 struct edge_list *elist;
6777 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
6781 /* Determine the number of edges in the flow graph by counting successor
6782 edges on each basic block. */
6783 for (x = 0; x < n_basic_blocks; x++)
6785 basic_block bb = BASIC_BLOCK (x);
6787 for (e = bb->succ; e; e = e->succ_next)
6790 /* Don't forget successors of the entry block. */
6791 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6794 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
6795 elist->num_blocks = block_count;
6796 elist->num_edges = num_edges;
6797 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
6801 /* Follow successors of the entry block, and register these edges. */
6802 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6804 elist->index_to_edge[num_edges] = e;
6808 for (x = 0; x < n_basic_blocks; x++)
6810 basic_block bb = BASIC_BLOCK (x);
6812 /* Follow all successors of blocks, and register these edges. */
6813 for (e = bb->succ; e; e = e->succ_next)
6815 elist->index_to_edge[num_edges] = e;
6822 /* This function free's memory associated with an edge list. */
6825 free_edge_list (elist)
6826 struct edge_list *elist;
6830 free (elist->index_to_edge);
6835 /* This function provides debug output showing an edge list. */
6838 print_edge_list (f, elist)
6840 struct edge_list *elist;
6843 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
6844 elist->num_blocks - 2, elist->num_edges);
6846 for (x = 0; x < elist->num_edges; x++)
6848 fprintf (f, " %-4d - edge(", x);
6849 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
6850 fprintf (f, "entry,");
6852 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
6854 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
6855 fprintf (f, "exit)\n");
6857 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
6861 /* This function provides an internal consistency check of an edge list,
6862 verifying that all edges are present, and that there are no
6866 verify_edge_list (f, elist)
6868 struct edge_list *elist;
6870 int x, pred, succ, index;
6873 for (x = 0; x < n_basic_blocks; x++)
6875 basic_block bb = BASIC_BLOCK (x);
6877 for (e = bb->succ; e; e = e->succ_next)
6879 pred = e->src->index;
6880 succ = e->dest->index;
6881 index = EDGE_INDEX (elist, e->src, e->dest);
6882 if (index == EDGE_INDEX_NO_EDGE)
6884 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
6887 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
6888 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
6889 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
6890 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
6891 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
6892 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
6895 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6897 pred = e->src->index;
6898 succ = e->dest->index;
6899 index = EDGE_INDEX (elist, e->src, e->dest);
6900 if (index == EDGE_INDEX_NO_EDGE)
6902 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
6905 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
6906 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
6907 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
6908 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
6909 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
6910 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
6912 /* We've verified that all the edges are in the list, no lets make sure
6913 there are no spurious edges in the list. */
6915 for (pred = 0; pred < n_basic_blocks; pred++)
6916 for (succ = 0; succ < n_basic_blocks; succ++)
6918 basic_block p = BASIC_BLOCK (pred);
6919 basic_block s = BASIC_BLOCK (succ);
6923 for (e = p->succ; e; e = e->succ_next)
6929 for (e = s->pred; e; e = e->pred_next)
6935 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
6936 == EDGE_INDEX_NO_EDGE && found_edge != 0)
6937 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
6939 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
6940 != EDGE_INDEX_NO_EDGE && found_edge == 0)
6941 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
6942 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
6943 BASIC_BLOCK (succ)));
6945 for (succ = 0; succ < n_basic_blocks; succ++)
6947 basic_block p = ENTRY_BLOCK_PTR;
6948 basic_block s = BASIC_BLOCK (succ);
6952 for (e = p->succ; e; e = e->succ_next)
6958 for (e = s->pred; e; e = e->pred_next)
6964 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
6965 == EDGE_INDEX_NO_EDGE && found_edge != 0)
6966 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
6968 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
6969 != EDGE_INDEX_NO_EDGE && found_edge == 0)
6970 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
6971 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
6972 BASIC_BLOCK (succ)));
6974 for (pred = 0; pred < n_basic_blocks; pred++)
6976 basic_block p = BASIC_BLOCK (pred);
6977 basic_block s = EXIT_BLOCK_PTR;
6981 for (e = p->succ; e; e = e->succ_next)
6987 for (e = s->pred; e; e = e->pred_next)
6993 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
6994 == EDGE_INDEX_NO_EDGE && found_edge != 0)
6995 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
6997 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
6998 != EDGE_INDEX_NO_EDGE && found_edge == 0)
6999 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7000 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7005 /* This routine will determine what, if any, edge there is between
7006 a specified predecessor and successor. */
7009 find_edge_index (edge_list, pred, succ)
7010 struct edge_list *edge_list;
7011 basic_block pred, succ;
7014 for (x = 0; x < NUM_EDGES (edge_list); x++)
7016 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7017 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7020 return (EDGE_INDEX_NO_EDGE);
7023 /* This function will remove an edge from the flow graph. */
7029 edge last_pred = NULL;
7030 edge last_succ = NULL;
7032 basic_block src, dest;
7035 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7041 last_succ->succ_next = e->succ_next;
7043 src->succ = e->succ_next;
7045 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7051 last_pred->pred_next = e->pred_next;
7053 dest->pred = e->pred_next;
7059 /* This routine will remove any fake successor edges for a basic block.
7060 When the edge is removed, it is also removed from whatever predecessor
7064 remove_fake_successors (bb)
7068 for (e = bb->succ; e;)
7072 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7077 /* This routine will remove all fake edges from the flow graph. If
7078 we remove all fake successors, it will automatically remove all
7079 fake predecessors. */
7082 remove_fake_edges ()
7086 for (x = 0; x < n_basic_blocks; x++)
7087 remove_fake_successors (BASIC_BLOCK (x));
7089 /* We've handled all successors except the entry block's. */
7090 remove_fake_successors (ENTRY_BLOCK_PTR);
7093 /* This function will add a fake edge between any block which has no
7094 successors, and the exit block. Some data flow equations require these
7098 add_noreturn_fake_exit_edges ()
7102 for (x = 0; x < n_basic_blocks; x++)
7103 if (BASIC_BLOCK (x)->succ == NULL)
7104 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7107 /* This function adds a fake edge between any infinite loops to the
7108 exit block. Some optimizations require a path from each node to
7111 See also Morgan, Figure 3.10, pp. 82-83.
7113 The current implementation is ugly, not attempting to minimize the
7114 number of inserted fake edges. To reduce the number of fake edges
7115 to insert, add fake edges from _innermost_ loops containing only
7116 nodes not reachable from the exit block. */
7119 connect_infinite_loops_to_exit ()
7121 basic_block unvisited_block;
7123 /* Perform depth-first search in the reverse graph to find nodes
7124 reachable from the exit block. */
7125 struct depth_first_search_dsS dfs_ds;
7127 flow_dfs_compute_reverse_init (&dfs_ds);
7128 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7130 /* Repeatedly add fake edges, updating the unreachable nodes. */
7133 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7134 if (!unvisited_block)
7136 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7137 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7140 flow_dfs_compute_reverse_finish (&dfs_ds);
7145 /* Redirect an edge's successor from one block to another. */
7148 redirect_edge_succ (e, new_succ)
7150 basic_block new_succ;
7154 /* Disconnect the edge from the old successor block. */
7155 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7157 *pe = (*pe)->pred_next;
7159 /* Reconnect the edge to the new successor block. */
7160 e->pred_next = new_succ->pred;
7165 /* Redirect an edge's predecessor from one block to another. */
7168 redirect_edge_pred (e, new_pred)
7170 basic_block new_pred;
7174 /* Disconnect the edge from the old predecessor block. */
7175 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7177 *pe = (*pe)->succ_next;
7179 /* Reconnect the edge to the new predecessor block. */
7180 e->succ_next = new_pred->succ;
7185 /* Dump the list of basic blocks in the bitmap NODES. */
7188 flow_nodes_print (str, nodes, file)
7190 const sbitmap nodes;
7198 fprintf (file, "%s { ", str);
7199 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
7200 fputs ("}\n", file);
7204 /* Dump the list of edges in the array EDGE_LIST. */
7207 flow_edge_list_print (str, edge_list, num_edges, file)
7209 const edge *edge_list;
7218 fprintf (file, "%s { ", str);
7219 for (i = 0; i < num_edges; i++)
7220 fprintf (file, "%d->%d ", edge_list[i]->src->index,
7221 edge_list[i]->dest->index);
7222 fputs ("}\n", file);
7226 /* Dump loop related CFG information. */
7229 flow_loops_cfg_dump (loops, file)
7230 const struct loops *loops;
7235 if (! loops->num || ! file || ! loops->cfg.dom)
7238 for (i = 0; i < n_basic_blocks; i++)
7242 fprintf (file, ";; %d succs { ", i);
7243 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
7244 fprintf (file, "%d ", succ->dest->index);
7245 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
7248 /* Dump the DFS node order. */
7249 if (loops->cfg.dfs_order)
7251 fputs (";; DFS order: ", file);
7252 for (i = 0; i < n_basic_blocks; i++)
7253 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
7256 /* Dump the reverse completion node order. */
7257 if (loops->cfg.rc_order)
7259 fputs (";; RC order: ", file);
7260 for (i = 0; i < n_basic_blocks; i++)
7261 fprintf (file, "%d ", loops->cfg.rc_order[i]);
7266 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7269 flow_loop_nested_p (outer, loop)
7273 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
7277 /* Dump the loop information specified by LOOP to the stream FILE
7278 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7280 flow_loop_dump (loop, file, loop_dump_aux, verbose)
7281 const struct loop *loop;
7283 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7286 if (! loop || ! loop->header)
7289 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
7290 loop->num, INSN_UID (loop->first->head),
7291 INSN_UID (loop->last->end),
7292 loop->shared ? " shared" : "",
7293 loop->invalid ? " invalid" : "");
7294 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
7295 loop->header->index, loop->latch->index,
7296 loop->pre_header ? loop->pre_header->index : -1,
7297 loop->first->index, loop->last->index);
7298 fprintf (file, ";; depth %d, level %d, outer %ld\n",
7299 loop->depth, loop->level,
7300 (long) (loop->outer ? loop->outer->num : -1));
7302 if (loop->pre_header_edges)
7303 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
7304 loop->num_pre_header_edges, file);
7305 flow_edge_list_print (";; entry edges", loop->entry_edges,
7306 loop->num_entries, file);
7307 fprintf (file, ";; %d", loop->num_nodes);
7308 flow_nodes_print (" nodes", loop->nodes, file);
7309 flow_edge_list_print (";; exit edges", loop->exit_edges,
7310 loop->num_exits, file);
7311 if (loop->exits_doms)
7312 flow_nodes_print (";; exit doms", loop->exits_doms, file);
7314 loop_dump_aux (loop, file, verbose);
7318 /* Dump the loop information specified by LOOPS to the stream FILE,
7319 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7321 flow_loops_dump (loops, file, loop_dump_aux, verbose)
7322 const struct loops *loops;
7324 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7330 num_loops = loops->num;
7331 if (! num_loops || ! file)
7334 fprintf (file, ";; %d loops found, %d levels\n",
7335 num_loops, loops->levels);
7337 for (i = 0; i < num_loops; i++)
7339 struct loop *loop = &loops->array[i];
7341 flow_loop_dump (loop, file, loop_dump_aux, verbose);
7347 for (j = 0; j < i; j++)
7349 struct loop *oloop = &loops->array[j];
7351 if (loop->header == oloop->header)
7356 smaller = loop->num_nodes < oloop->num_nodes;
7358 /* If the union of LOOP and OLOOP is different than
7359 the larger of LOOP and OLOOP then LOOP and OLOOP
7360 must be disjoint. */
7361 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
7362 smaller ? oloop : loop);
7364 ";; loop header %d shared by loops %d, %d %s\n",
7365 loop->header->index, i, j,
7366 disjoint ? "disjoint" : "nested");
7373 flow_loops_cfg_dump (loops, file);
7377 /* Free all the memory allocated for LOOPS. */
7380 flow_loops_free (loops)
7381 struct loops *loops;
7390 /* Free the loop descriptors. */
7391 for (i = 0; i < loops->num; i++)
7393 struct loop *loop = &loops->array[i];
7395 if (loop->pre_header_edges)
7396 free (loop->pre_header_edges);
7398 sbitmap_free (loop->nodes);
7399 if (loop->entry_edges)
7400 free (loop->entry_edges);
7401 if (loop->exit_edges)
7402 free (loop->exit_edges);
7403 if (loop->exits_doms)
7404 sbitmap_free (loop->exits_doms);
7406 free (loops->array);
7407 loops->array = NULL;
7410 sbitmap_vector_free (loops->cfg.dom);
7411 if (loops->cfg.dfs_order)
7412 free (loops->cfg.dfs_order);
7414 if (loops->shared_headers)
7415 sbitmap_free (loops->shared_headers);
7420 /* Find the entry edges into the loop with header HEADER and nodes
7421 NODES and store in ENTRY_EDGES array. Return the number of entry
7422 edges from the loop. */
7425 flow_loop_entry_edges_find (header, nodes, entry_edges)
7427 const sbitmap nodes;
7433 *entry_edges = NULL;
7436 for (e = header->pred; e; e = e->pred_next)
7438 basic_block src = e->src;
7440 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7447 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
7450 for (e = header->pred; e; e = e->pred_next)
7452 basic_block src = e->src;
7454 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7455 (*entry_edges)[num_entries++] = e;
7462 /* Find the exit edges from the loop using the bitmap of loop nodes
7463 NODES and store in EXIT_EDGES array. Return the number of
7464 exit edges from the loop. */
7467 flow_loop_exit_edges_find (nodes, exit_edges)
7468 const sbitmap nodes;
7477 /* Check all nodes within the loop to see if there are any
7478 successors not in the loop. Note that a node may have multiple
7479 exiting edges ????? A node can have one jumping edge and one fallthru
7480 edge so only one of these can exit the loop. */
7482 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7483 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7485 basic_block dest = e->dest;
7487 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7495 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
7497 /* Store all exiting edges into an array. */
7499 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7500 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7502 basic_block dest = e->dest;
7504 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7505 (*exit_edges)[num_exits++] = e;
7513 /* Find the nodes contained within the loop with header HEADER and
7514 latch LATCH and store in NODES. Return the number of nodes within
7518 flow_loop_nodes_find (header, latch, nodes)
7527 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
7530 /* Start with only the loop header in the set of loop nodes. */
7531 sbitmap_zero (nodes);
7532 SET_BIT (nodes, header->index);
7534 header->loop_depth++;
7536 /* Push the loop latch on to the stack. */
7537 if (! TEST_BIT (nodes, latch->index))
7539 SET_BIT (nodes, latch->index);
7540 latch->loop_depth++;
7542 stack[sp++] = latch;
7551 for (e = node->pred; e; e = e->pred_next)
7553 basic_block ancestor = e->src;
7555 /* If each ancestor not marked as part of loop, add to set of
7556 loop nodes and push on to stack. */
7557 if (ancestor != ENTRY_BLOCK_PTR
7558 && ! TEST_BIT (nodes, ancestor->index))
7560 SET_BIT (nodes, ancestor->index);
7561 ancestor->loop_depth++;
7563 stack[sp++] = ancestor;
7571 /* Compute the depth first search order and store in the array
7572 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7573 RC_ORDER is non-zero, return the reverse completion number for each
7574 node. Returns the number of nodes visited. A depth first search
7575 tries to get as far away from the starting point as quickly as
7579 flow_depth_first_order_compute (dfs_order, rc_order)
7586 int rcnum = n_basic_blocks - 1;
7589 /* Allocate stack for back-tracking up CFG. */
7590 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
7593 /* Allocate bitmap to track nodes that have been visited. */
7594 visited = sbitmap_alloc (n_basic_blocks);
7596 /* None of the nodes in the CFG have been visited yet. */
7597 sbitmap_zero (visited);
7599 /* Push the first edge on to the stack. */
7600 stack[sp++] = ENTRY_BLOCK_PTR->succ;
7608 /* Look at the edge on the top of the stack. */
7613 /* Check if the edge destination has been visited yet. */
7614 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
7616 /* Mark that we have visited the destination. */
7617 SET_BIT (visited, dest->index);
7620 dfs_order[dfsnum++] = dest->index;
7624 /* Since the DEST node has been visited for the first
7625 time, check its successors. */
7626 stack[sp++] = dest->succ;
7630 /* There are no successors for the DEST node so assign
7631 its reverse completion number. */
7633 rc_order[rcnum--] = dest->index;
7638 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
7640 /* There are no more successors for the SRC node
7641 so assign its reverse completion number. */
7643 rc_order[rcnum--] = src->index;
7647 stack[sp - 1] = e->succ_next;
7654 sbitmap_free (visited);
7656 /* The number of nodes visited should not be greater than
7658 if (dfsnum > n_basic_blocks)
7661 /* There are some nodes left in the CFG that are unreachable. */
7662 if (dfsnum < n_basic_blocks)
7667 /* Compute the depth first search order on the _reverse_ graph and
7668 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7669 Returns the number of nodes visited.
7671 The computation is split into three pieces:
7673 flow_dfs_compute_reverse_init () creates the necessary data
7676 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7677 structures. The block will start the search.
7679 flow_dfs_compute_reverse_execute () continues (or starts) the
7680 search using the block on the top of the stack, stopping when the
7683 flow_dfs_compute_reverse_finish () destroys the necessary data
7686 Thus, the user will probably call ..._init(), call ..._add_bb() to
7687 add a beginning basic block to the stack, call ..._execute(),
7688 possibly add another bb to the stack and again call ..._execute(),
7689 ..., and finally call _finish(). */
7691 /* Initialize the data structures used for depth-first search on the
7692 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7693 added to the basic block stack. DATA is the current depth-first
7694 search context. If INITIALIZE_STACK is non-zero, there is an
7695 element on the stack. */
7698 flow_dfs_compute_reverse_init (data)
7699 depth_first_search_ds data;
7701 /* Allocate stack for back-tracking up CFG. */
7703 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
7704 * sizeof (basic_block));
7707 /* Allocate bitmap to track nodes that have been visited. */
7708 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
7710 /* None of the nodes in the CFG have been visited yet. */
7711 sbitmap_zero (data->visited_blocks);
7716 /* Add the specified basic block to the top of the dfs data
7717 structures. When the search continues, it will start at the
7721 flow_dfs_compute_reverse_add_bb (data, bb)
7722 depth_first_search_ds data;
7725 data->stack[data->sp++] = bb;
7729 /* Continue the depth-first search through the reverse graph starting
7730 with the block at the stack's top and ending when the stack is
7731 empty. Visited nodes are marked. Returns an unvisited basic
7732 block, or NULL if there is none available. */
7735 flow_dfs_compute_reverse_execute (data)
7736 depth_first_search_ds data;
7742 while (data->sp > 0)
7744 bb = data->stack[--data->sp];
7746 /* Mark that we have visited this node. */
7747 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
7749 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
7751 /* Perform depth-first search on adjacent vertices. */
7752 for (e = bb->pred; e; e = e->pred_next)
7753 flow_dfs_compute_reverse_add_bb (data, e->src);
7757 /* Determine if there are unvisited basic blocks. */
7758 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
7759 if (!TEST_BIT (data->visited_blocks, i))
7760 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
7764 /* Destroy the data structures needed for depth-first search on the
7768 flow_dfs_compute_reverse_finish (data)
7769 depth_first_search_ds data;
7772 sbitmap_free (data->visited_blocks);
7777 /* Find the root node of the loop pre-header extended basic block and
7778 the edges along the trace from the root node to the loop header. */
7781 flow_loop_pre_header_scan (loop)
7787 loop->num_pre_header_edges = 0;
7789 if (loop->num_entries != 1)
7792 ebb = loop->entry_edges[0]->src;
7794 if (ebb != ENTRY_BLOCK_PTR)
7798 /* Count number of edges along trace from loop header to
7799 root of pre-header extended basic block. Usually this is
7800 only one or two edges. */
7802 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
7804 ebb = ebb->pred->src;
7808 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
7809 loop->num_pre_header_edges = num;
7811 /* Store edges in order that they are followed. The source
7812 of the first edge is the root node of the pre-header extended
7813 basic block and the destination of the last last edge is
7815 for (e = loop->entry_edges[0]; num; e = e->src->pred)
7817 loop->pre_header_edges[--num] = e;
7823 /* Return the block for the pre-header of the loop with header
7824 HEADER where DOM specifies the dominator information. Return NULL if
7825 there is no pre-header. */
7828 flow_loop_pre_header_find (header, dom)
7832 basic_block pre_header;
7835 /* If block p is a predecessor of the header and is the only block
7836 that the header does not dominate, then it is the pre-header. */
7838 for (e = header->pred; e; e = e->pred_next)
7840 basic_block node = e->src;
7842 if (node != ENTRY_BLOCK_PTR
7843 && ! TEST_BIT (dom[node->index], header->index))
7845 if (pre_header == NULL)
7849 /* There are multiple edges into the header from outside
7850 the loop so there is no pre-header block. */
7859 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
7860 previously added. The insertion algorithm assumes that the loops
7861 are added in the order found by a depth first search of the CFG. */
7864 flow_loop_tree_node_add (prevloop, loop)
7865 struct loop *prevloop;
7869 if (flow_loop_nested_p (prevloop, loop))
7871 prevloop->inner = loop;
7872 loop->outer = prevloop;
7876 while (prevloop->outer)
7878 if (flow_loop_nested_p (prevloop->outer, loop))
7880 prevloop->next = loop;
7881 loop->outer = prevloop->outer;
7884 prevloop = prevloop->outer;
7887 prevloop->next = loop;
7891 /* Build the loop hierarchy tree for LOOPS. */
7894 flow_loops_tree_build (loops)
7895 struct loops *loops;
7900 num_loops = loops->num;
7904 /* Root the loop hierarchy tree with the first loop found.
7905 Since we used a depth first search this should be the
7907 loops->tree = &loops->array[0];
7908 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
7910 /* Add the remaining loops to the tree. */
7911 for (i = 1; i < num_loops; i++)
7912 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
7915 /* Helper function to compute loop nesting depth and enclosed loop level
7916 for the natural loop specified by LOOP at the loop depth DEPTH.
7917 Returns the loop level. */
7920 flow_loop_level_compute (loop, depth)
7930 /* Traverse loop tree assigning depth and computing level as the
7931 maximum level of all the inner loops of this loop. The loop
7932 level is equivalent to the height of the loop in the loop tree
7933 and corresponds to the number of enclosed loop levels (including
7935 for (inner = loop->inner; inner; inner = inner->next)
7939 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
7944 loop->level = level;
7945 loop->depth = depth;
7949 /* Compute the loop nesting depth and enclosed loop level for the loop
7950 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
7954 flow_loops_level_compute (loops)
7955 struct loops *loops;
7961 /* Traverse all the outer level loops. */
7962 for (loop = loops->tree; loop; loop = loop->next)
7964 level = flow_loop_level_compute (loop, 1);
7972 /* Find all the natural loops in the function and save in LOOPS structure
7973 and recalculate loop_depth information in basic block structures.
7974 FLAGS controls which loop information is collected.
7975 Return the number of natural loops found. */
7978 flow_loops_find (loops, flags)
7979 struct loops *loops;
7991 /* This function cannot be repeatedly called with different
7992 flags to build up the loop information. The loop tree
7993 must always be built if this function is called. */
7994 if (! (flags & LOOP_TREE))
7997 memset (loops, 0, sizeof (*loops));
7999 /* Taking care of this degenerate case makes the rest of
8000 this code simpler. */
8001 if (n_basic_blocks == 0)
8007 /* Compute the dominators. */
8008 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8009 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
8011 /* Count the number of loop edges (back edges). This should be the
8012 same as the number of natural loops. */
8015 for (b = 0; b < n_basic_blocks; b++)
8019 header = BASIC_BLOCK (b);
8020 header->loop_depth = 0;
8022 for (e = header->pred; e; e = e->pred_next)
8024 basic_block latch = e->src;
8026 /* Look for back edges where a predecessor is dominated
8027 by this block. A natural loop has a single entry
8028 node (header) that dominates all the nodes in the
8029 loop. It also has single back edge to the header
8030 from a latch node. Note that multiple natural loops
8031 may share the same header. */
8032 if (b != header->index)
8035 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8042 /* Compute depth first search order of the CFG so that outer
8043 natural loops will be found before inner natural loops. */
8044 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8045 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8046 flow_depth_first_order_compute (dfs_order, rc_order);
8048 /* Allocate loop structures. */
8050 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8052 headers = sbitmap_alloc (n_basic_blocks);
8053 sbitmap_zero (headers);
8055 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8056 sbitmap_zero (loops->shared_headers);
8058 /* Find and record information about all the natural loops
8061 for (b = 0; b < n_basic_blocks; b++)
8065 /* Search the nodes of the CFG in reverse completion order
8066 so that we can find outer loops first. */
8067 header = BASIC_BLOCK (rc_order[b]);
8069 /* Look for all the possible latch blocks for this header. */
8070 for (e = header->pred; e; e = e->pred_next)
8072 basic_block latch = e->src;
8074 /* Look for back edges where a predecessor is dominated
8075 by this block. A natural loop has a single entry
8076 node (header) that dominates all the nodes in the
8077 loop. It also has single back edge to the header
8078 from a latch node. Note that multiple natural loops
8079 may share the same header. */
8080 if (latch != ENTRY_BLOCK_PTR
8081 && TEST_BIT (dom[latch->index], header->index))
8085 loop = loops->array + num_loops;
8087 loop->header = header;
8088 loop->latch = latch;
8089 loop->num = num_loops;
8096 for (i = 0; i < num_loops; i++)
8098 struct loop *loop = &loops->array[i];
8101 /* Keep track of blocks that are loop headers so
8102 that we can tell which loops should be merged. */
8103 if (TEST_BIT (headers, loop->header->index))
8104 SET_BIT (loops->shared_headers, loop->header->index);
8105 SET_BIT (headers, loop->header->index);
8107 /* Find nodes contained within the loop. */
8108 loop->nodes = sbitmap_alloc (n_basic_blocks);
8110 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8112 /* Compute first and last blocks within the loop.
8113 These are often the same as the loop header and
8114 loop latch respectively, but this is not always
8117 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
8119 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
8121 if (flags & LOOP_EDGES)
8123 /* Find edges which enter the loop header.
8124 Note that the entry edges should only
8125 enter the header of a natural loop. */
8127 = flow_loop_entry_edges_find (loop->header,
8129 &loop->entry_edges);
8131 /* Find edges which exit the loop. */
8133 = flow_loop_exit_edges_find (loop->nodes,
8136 /* Determine which loop nodes dominate all the exits
8138 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8139 sbitmap_copy (loop->exits_doms, loop->nodes);
8140 for (j = 0; j < loop->num_exits; j++)
8141 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8142 dom[loop->exit_edges[j]->src->index]);
8144 /* The header of a natural loop must dominate
8146 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8150 if (flags & LOOP_PRE_HEADER)
8152 /* Look to see if the loop has a pre-header node. */
8154 = flow_loop_pre_header_find (loop->header, dom);
8156 flow_loop_pre_header_scan (loop);
8160 /* Natural loops with shared headers may either be disjoint or
8161 nested. Disjoint loops with shared headers cannot be inner
8162 loops and should be merged. For now just mark loops that share
8164 for (i = 0; i < num_loops; i++)
8165 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
8166 loops->array[i].shared = 1;
8168 sbitmap_free (headers);
8171 loops->num = num_loops;
8173 /* Save CFG derived information to avoid recomputing it. */
8174 loops->cfg.dom = dom;
8175 loops->cfg.dfs_order = dfs_order;
8176 loops->cfg.rc_order = rc_order;
8178 /* Build the loop hierarchy tree. */
8179 flow_loops_tree_build (loops);
8181 /* Assign the loop nesting depth and enclosed loop level for each
8183 loops->levels = flow_loops_level_compute (loops);
8189 /* Update the information regarding the loops in the CFG
8190 specified by LOOPS. */
8192 flow_loops_update (loops, flags)
8193 struct loops *loops;
8196 /* One day we may want to update the current loop data. For now
8197 throw away the old stuff and rebuild what we need. */
8199 flow_loops_free (loops);
8201 return flow_loops_find (loops, flags);
8205 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
8208 flow_loop_outside_edge_p (loop, e)
8209 const struct loop *loop;
8212 if (e->dest != loop->header)
8214 return (e->src == ENTRY_BLOCK_PTR)
8215 || ! TEST_BIT (loop->nodes, e->src->index);
8218 /* Clear LOG_LINKS fields of insns in a chain.
8219 Also clear the global_live_at_{start,end} fields of the basic block
8223 clear_log_links (insns)
8229 for (i = insns; i; i = NEXT_INSN (i))
8233 for (b = 0; b < n_basic_blocks; b++)
8235 basic_block bb = BASIC_BLOCK (b);
8237 bb->global_live_at_start = NULL;
8238 bb->global_live_at_end = NULL;
8241 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
8242 EXIT_BLOCK_PTR->global_live_at_start = NULL;
8245 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
8246 correspond to the hard registers, if any, set in that map. This
8247 could be done far more efficiently by having all sorts of special-cases
8248 with moving single words, but probably isn't worth the trouble. */
8251 reg_set_to_hard_reg_set (to, from)
8257 EXECUTE_IF_SET_IN_BITMAP
8260 if (i >= FIRST_PSEUDO_REGISTER)
8262 SET_HARD_REG_BIT (*to, i);
8266 /* Called once at intialization time. */
8271 static int initialized;
8275 gcc_obstack_init (&flow_obstack);
8276 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
8281 obstack_free (&flow_obstack, flow_firstobj);
8282 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);