1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 88, 92-98, 1999 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 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 "basic-block.h"
127 #include "insn-config.h"
129 #include "hard-reg-set.h"
132 #include "function.h"
136 #include "insn-flags.h"
140 #define obstack_chunk_alloc xmalloc
141 #define obstack_chunk_free free
144 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
145 the stack pointer does not matter. The value is tested only in
146 functions that have frame pointers.
147 No definition is equivalent to always zero. */
148 #ifndef EXIT_IGNORE_STACK
149 #define EXIT_IGNORE_STACK 0
152 #ifndef HAVE_epilogue
153 #define HAVE_epilogue 0
156 #ifndef HAVE_prologue
157 #define HAVE_prologue 0
160 /* The contents of the current function definition are allocated
161 in this obstack, and all are freed at the end of the function.
162 For top-level functions, this is temporary_obstack.
163 Separate obstacks are made for nested functions. */
165 extern struct obstack *function_obstack;
167 /* Number of basic blocks in the current function. */
171 /* Number of edges in the current function. */
175 /* The basic block array. */
177 varray_type basic_block_info;
179 /* The special entry and exit blocks. */
181 struct basic_block_def entry_exit_blocks[2]
186 NULL, /* local_set */
187 NULL, /* global_live_at_start */
188 NULL, /* global_live_at_end */
190 ENTRY_BLOCK, /* index */
192 -1, -1 /* eh_beg, eh_end */
199 NULL, /* local_set */
200 NULL, /* global_live_at_start */
201 NULL, /* global_live_at_end */
203 EXIT_BLOCK, /* index */
205 -1, -1 /* eh_beg, eh_end */
209 /* Nonzero if the second flow pass has completed. */
212 /* Maximum register number used in this function, plus one. */
216 /* Indexed by n, giving various register information */
218 varray_type reg_n_info;
220 /* Size of the reg_n_info table. */
222 unsigned int reg_n_max;
224 /* Element N is the next insn that uses (hard or pseudo) register number N
225 within the current basic block; or zero, if there is no such insn.
226 This is valid only during the final backward scan in propagate_block. */
228 static rtx *reg_next_use;
230 /* Size of a regset for the current function,
231 in (1) bytes and (2) elements. */
236 /* Regset of regs live when calls to `setjmp'-like functions happen. */
237 /* ??? Does this exist only for the setjmp-clobbered warning message? */
239 regset regs_live_at_setjmp;
241 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
242 that have to go in the same hard reg.
243 The first two regs in the list are a pair, and the next two
244 are another pair, etc. */
247 /* Depth within loops of basic block being scanned for lifetime analysis,
248 plus one. This is the weight attached to references to registers. */
250 static int loop_depth;
252 /* During propagate_block, this is non-zero if the value of CC0 is live. */
256 /* During propagate_block, this contains a list of all the MEMs we are
257 tracking for dead store elimination. */
259 static rtx mem_set_list;
261 /* Set of registers that may be eliminable. These are handled specially
262 in updating regs_ever_live. */
264 static HARD_REG_SET elim_reg_set;
266 /* The basic block structure for every insn, indexed by uid. */
268 varray_type basic_block_for_insn;
270 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
271 /* ??? Should probably be using LABEL_NUSES instead. It would take a
272 bit of surgery to be able to use or co-opt the routines in jump. */
274 static rtx label_value_list;
276 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
278 #define INSN_VOLATILE(INSN) bitmap_bit_p (uid_volatile, INSN_UID (INSN))
279 #define SET_INSN_VOLATILE(INSN) bitmap_set_bit (uid_volatile, INSN_UID (INSN))
280 static bitmap uid_volatile;
282 /* Forward declarations */
283 static int count_basic_blocks PROTO((rtx));
284 static rtx find_basic_blocks_1 PROTO((rtx));
285 static void create_basic_block PROTO((int, rtx, rtx, rtx));
286 static void clear_edges PROTO((void));
287 static void make_edges PROTO((rtx));
288 static void make_edge PROTO((sbitmap *, basic_block,
290 static void make_label_edge PROTO((sbitmap *, basic_block,
292 static void make_eh_edge PROTO((sbitmap *, eh_nesting_info *,
293 basic_block, rtx, int));
294 static void mark_critical_edges PROTO((void));
295 static void move_stray_eh_region_notes PROTO((void));
296 static void record_active_eh_regions PROTO((rtx));
298 static void commit_one_edge_insertion PROTO((edge));
300 static void delete_unreachable_blocks PROTO((void));
301 static void delete_eh_regions PROTO((void));
302 static int can_delete_note_p PROTO((rtx));
303 static int delete_block PROTO((basic_block));
304 static void expunge_block PROTO((basic_block));
305 static rtx flow_delete_insn PROTO((rtx));
306 static int can_delete_label_p PROTO((rtx));
307 static int merge_blocks_move_predecessor_nojumps PROTO((basic_block,
309 static int merge_blocks_move_successor_nojumps PROTO((basic_block,
311 static void merge_blocks_nomove PROTO((basic_block, basic_block));
312 static int merge_blocks PROTO((edge,basic_block,basic_block));
313 static void try_merge_blocks PROTO((void));
314 static void tidy_fallthru_edge PROTO((edge,basic_block,basic_block));
316 static int verify_wide_reg_1 PROTO((rtx *, void *));
317 static void verify_wide_reg PROTO((int, rtx, rtx));
318 static void verify_local_live_at_start PROTO((regset, basic_block));
319 static int set_noop_p PROTO((rtx));
320 static int noop_move_p PROTO((rtx));
321 static void notice_stack_pointer_modification PROTO ((rtx, rtx, void *));
322 static void record_volatile_insns PROTO((rtx));
323 static void mark_reg PROTO((regset, rtx));
324 static void mark_regs_live_at_end PROTO((regset));
325 static void life_analysis_1 PROTO((rtx, int, int));
326 static void calculate_global_regs_live PROTO((sbitmap, sbitmap, int));
327 static void propagate_block PROTO((regset, rtx, rtx,
329 static int insn_dead_p PROTO((rtx, regset, int, rtx));
330 static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
331 static void mark_set_regs PROTO((regset, regset, rtx,
333 static void mark_set_1 PROTO((regset, regset, rtx,
336 static void find_auto_inc PROTO((regset, rtx, rtx));
337 static int try_pre_increment_1 PROTO((rtx));
338 static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
340 static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
341 void dump_flow_info PROTO((FILE *));
342 void debug_flow_info PROTO((void));
343 static void dump_edge_info PROTO((FILE *, edge, int));
345 static void count_reg_sets_1 PROTO ((rtx));
346 static void count_reg_sets PROTO ((rtx));
347 static void count_reg_references PROTO ((rtx));
348 static void invalidate_mems_from_autoinc PROTO ((rtx));
349 static void remove_edge PROTO ((edge));
350 static void remove_fake_successors PROTO ((basic_block));
351 static void flow_nodes_print PROTO ((const char *, const sbitmap, FILE *));
352 static void flow_exits_print PROTO ((const char *, const edge *, int, FILE *));
353 static void flow_loops_cfg_dump PROTO ((const struct loops *, FILE *));
354 static int flow_loop_nested_p PROTO ((struct loop *, struct loop *));
355 static int flow_loop_exits_find PROTO ((const sbitmap, edge **));
356 static int flow_loop_nodes_find PROTO ((basic_block, basic_block, sbitmap));
357 static int flow_depth_first_order_compute PROTO ((int *));
358 static basic_block flow_loop_pre_header_find PROTO ((basic_block, const sbitmap *));
359 static void flow_loop_tree_node_add PROTO ((struct loop *, struct loop *));
360 static void flow_loops_tree_build PROTO ((struct loops *));
361 static int flow_loop_level_compute PROTO ((struct loop *, int));
362 static int flow_loops_level_compute PROTO ((struct loops *));
364 /* This function is always defined so it can be called from the
365 debugger, and it is declared extern so we don't get warnings about
367 void verify_flow_info PROTO ((void));
368 int flow_loop_outside_edge_p PROTO ((const struct loop *, edge));
370 /* Find basic blocks of the current function.
371 F is the first insn of the function and NREGS the number of register
375 find_basic_blocks (f, nregs, file, do_cleanup)
377 int nregs ATTRIBUTE_UNUSED;
378 FILE *file ATTRIBUTE_UNUSED;
383 /* Flush out existing data. */
384 if (basic_block_info != NULL)
390 /* Clear bb->aux on all extant basic blocks. We'll use this as a
391 tag for reuse during create_basic_block, just in case some pass
392 copies around basic block notes improperly. */
393 for (i = 0; i < n_basic_blocks; ++i)
394 BASIC_BLOCK (i)->aux = NULL;
396 VARRAY_FREE (basic_block_info);
399 n_basic_blocks = count_basic_blocks (f);
401 /* Size the basic block table. The actual structures will be allocated
402 by find_basic_blocks_1, since we want to keep the structure pointers
403 stable across calls to find_basic_blocks. */
404 /* ??? This whole issue would be much simpler if we called find_basic_blocks
405 exactly once, and thereafter we don't have a single long chain of
406 instructions at all until close to the end of compilation when we
407 actually lay them out. */
409 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
411 label_value_list = find_basic_blocks_1 (f);
413 /* Record the block to which an insn belongs. */
414 /* ??? This should be done another way, by which (perhaps) a label is
415 tagged directly with the basic block that it starts. It is used for
416 more than that currently, but IMO that is the only valid use. */
418 max_uid = get_max_uid ();
420 /* Leave space for insns life_analysis makes in some cases for auto-inc.
421 These cases are rare, so we don't need too much space. */
422 max_uid += max_uid / 10;
425 compute_bb_for_insn (max_uid);
427 /* Discover the edges of our cfg. */
429 record_active_eh_regions (f);
430 make_edges (label_value_list);
432 /* Delete unreachable blocks, then merge blocks when possible. */
436 delete_unreachable_blocks ();
437 move_stray_eh_region_notes ();
438 record_active_eh_regions (f);
442 /* Mark critical edges. */
444 mark_critical_edges ();
446 /* Kill the data we won't maintain. */
447 label_value_list = NULL_RTX;
449 #ifdef ENABLE_CHECKING
454 /* Count the basic blocks of the function. */
457 count_basic_blocks (f)
461 register RTX_CODE prev_code;
462 register int count = 0;
464 int call_had_abnormal_edge = 0;
465 rtx prev_call = NULL_RTX;
467 prev_code = JUMP_INSN;
468 for (insn = f; insn; insn = NEXT_INSN (insn))
470 register RTX_CODE code = GET_CODE (insn);
472 if (code == CODE_LABEL
473 || (GET_RTX_CLASS (code) == 'i'
474 && (prev_code == JUMP_INSN
475 || prev_code == BARRIER
476 || (prev_code == CALL_INSN && call_had_abnormal_edge))))
481 /* Record whether this call created an edge. */
482 if (code == CALL_INSN)
484 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
485 int region = (note ? XWINT (XEXP (note, 0), 0) : 1);
487 call_had_abnormal_edge = 0;
489 /* If there is a specified EH region, we have an edge. */
490 if (eh_region && region > 0)
491 call_had_abnormal_edge = 1;
494 /* If there is a nonlocal goto label and the specified
495 region number isn't -1, we have an edge. (0 means
496 no throw, but might have a nonlocal goto). */
497 if (nonlocal_goto_handler_labels && region >= 0)
498 call_had_abnormal_edge = 1;
501 else if (code != NOTE)
502 prev_call = NULL_RTX;
506 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
508 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
513 /* The rest of the compiler works a bit smoother when we don't have to
514 check for the edge case of do-nothing functions with no basic blocks. */
517 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
524 /* Find all basic blocks of the function whose first insn is F.
526 Collect and return a list of labels whose addresses are taken. This
527 will be used in make_edges for use with computed gotos. */
530 find_basic_blocks_1 (f)
533 register rtx insn, next;
534 int call_has_abnormal_edge = 0;
536 rtx bb_note = NULL_RTX;
537 rtx eh_list = NULL_RTX;
538 rtx label_value_list = NULL_RTX;
542 /* We process the instructions in a slightly different way than we did
543 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
544 closed out the previous block, so that it gets attached at the proper
545 place. Since this form should be equivalent to the previous,
546 count_basic_blocks continues to use the old form as a check. */
548 for (insn = f; insn; insn = next)
550 enum rtx_code code = GET_CODE (insn);
552 next = NEXT_INSN (insn);
554 if (code == CALL_INSN)
556 /* Record whether this call created an edge. */
557 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
558 int region = (note ? XWINT (XEXP (note, 0), 0) : 1);
559 call_has_abnormal_edge = 0;
561 /* If there is an EH region, we have an edge. */
562 if (eh_list && region > 0)
563 call_has_abnormal_edge = 1;
566 /* If there is a nonlocal goto label and the specified
567 region number isn't -1, we have an edge. (0 means
568 no throw, but might have a nonlocal goto). */
569 if (nonlocal_goto_handler_labels && region >= 0)
570 call_has_abnormal_edge = 1;
578 int kind = NOTE_LINE_NUMBER (insn);
580 /* Keep a LIFO list of the currently active exception notes. */
581 if (kind == NOTE_INSN_EH_REGION_BEG)
582 eh_list = alloc_INSN_LIST (insn, eh_list);
583 else if (kind == NOTE_INSN_EH_REGION_END)
586 eh_list = XEXP (eh_list, 1);
587 free_INSN_LIST_node (t);
590 /* Look for basic block notes with which to keep the
591 basic_block_info pointers stable. Unthread the note now;
592 we'll put it back at the right place in create_basic_block.
593 Or not at all if we've already found a note in this block. */
594 else if (kind == NOTE_INSN_BASIC_BLOCK)
596 if (bb_note == NULL_RTX)
598 next = flow_delete_insn (insn);
605 /* A basic block starts at a label. If we've closed one off due
606 to a barrier or some such, no need to do it again. */
607 if (head != NULL_RTX)
609 /* While we now have edge lists with which other portions of
610 the compiler might determine a call ending a basic block
611 does not imply an abnormal edge, it will be a bit before
612 everything can be updated. So continue to emit a noop at
613 the end of such a block. */
614 if (GET_CODE (end) == CALL_INSN)
616 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
617 end = emit_insn_after (nop, end);
620 create_basic_block (i++, head, end, bb_note);
627 /* A basic block ends at a jump. */
628 if (head == NULL_RTX)
632 /* ??? Make a special check for table jumps. The way this
633 happens is truly and amazingly gross. We are about to
634 create a basic block that contains just a code label and
635 an addr*vec jump insn. Worse, an addr_diff_vec creates
636 its own natural loop.
638 Prevent this bit of brain damage, pasting things together
639 correctly in make_edges.
641 The correct solution involves emitting the table directly
642 on the tablejump instruction as a note, or JUMP_LABEL. */
644 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
645 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
653 goto new_bb_inclusive;
656 /* A basic block ends at a barrier. It may be that an unconditional
657 jump already closed the basic block -- no need to do it again. */
658 if (head == NULL_RTX)
661 /* While we now have edge lists with which other portions of the
662 compiler might determine a call ending a basic block does not
663 imply an abnormal edge, it will be a bit before everything can
664 be updated. So continue to emit a noop at the end of such a
666 if (GET_CODE (end) == CALL_INSN)
668 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
669 end = emit_insn_after (nop, end);
671 goto new_bb_exclusive;
674 /* A basic block ends at a call that can either throw or
675 do a non-local goto. */
676 if (call_has_abnormal_edge)
679 if (head == NULL_RTX)
684 create_basic_block (i++, head, end, bb_note);
685 head = end = NULL_RTX;
692 if (GET_RTX_CLASS (code) == 'i')
694 if (head == NULL_RTX)
701 if (GET_RTX_CLASS (code) == 'i')
705 /* Make a list of all labels referred to other than by jumps
706 (which just don't have the REG_LABEL notes).
708 Make a special exception for labels followed by an ADDR*VEC,
709 as this would be a part of the tablejump setup code.
711 Make a special exception for the eh_return_stub_label, which
712 we know isn't part of any otherwise visible control flow. */
714 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
715 if (REG_NOTE_KIND (note) == REG_LABEL)
717 rtx lab = XEXP (note, 0), next;
719 if (lab == eh_return_stub_label)
721 else if ((next = next_nonnote_insn (lab)) != NULL
722 && GET_CODE (next) == JUMP_INSN
723 && (GET_CODE (PATTERN (next)) == ADDR_VEC
724 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
728 = alloc_EXPR_LIST (0, XEXP (note, 0), label_value_list);
733 if (head != NULL_RTX)
734 create_basic_block (i++, head, end, bb_note);
736 if (i != n_basic_blocks)
739 return label_value_list;
742 /* Create a new basic block consisting of the instructions between
743 HEAD and END inclusive. Reuses the note and basic block struct
744 in BB_NOTE, if any. */
747 create_basic_block (index, head, end, bb_note)
749 rtx head, end, bb_note;
754 && ! RTX_INTEGRATED_P (bb_note)
755 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
758 /* If we found an existing note, thread it back onto the chain. */
760 if (GET_CODE (head) == CODE_LABEL)
761 add_insn_after (bb_note, head);
764 add_insn_before (bb_note, head);
770 /* Otherwise we must create a note and a basic block structure.
771 Since we allow basic block structs in rtl, give the struct
772 the same lifetime by allocating it off the function obstack
773 rather than using malloc. */
775 bb = (basic_block) obstack_alloc (function_obstack, sizeof (*bb));
776 memset (bb, 0, sizeof (*bb));
778 if (GET_CODE (head) == CODE_LABEL)
779 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
782 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
785 NOTE_BASIC_BLOCK (bb_note) = bb;
788 /* Always include the bb note in the block. */
789 if (NEXT_INSN (end) == bb_note)
795 BASIC_BLOCK (index) = bb;
797 /* Tag the block so that we know it has been used when considering
798 other basic block notes. */
802 /* Records the basic block struct in BB_FOR_INSN, for every instruction
803 indexed by INSN_UID. MAX is the size of the array. */
806 compute_bb_for_insn (max)
811 if (basic_block_for_insn)
812 VARRAY_FREE (basic_block_for_insn);
813 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
815 for (i = 0; i < n_basic_blocks; ++i)
817 basic_block bb = BASIC_BLOCK (i);
824 int uid = INSN_UID (insn);
826 VARRAY_BB (basic_block_for_insn, uid) = bb;
829 insn = NEXT_INSN (insn);
834 /* Free the memory associated with the edge structures. */
842 for (i = 0; i < n_basic_blocks; ++i)
844 basic_block bb = BASIC_BLOCK (i);
846 for (e = bb->succ; e ; e = n)
856 for (e = ENTRY_BLOCK_PTR->succ; e ; e = n)
862 ENTRY_BLOCK_PTR->succ = 0;
863 EXIT_BLOCK_PTR->pred = 0;
868 /* Identify the edges between basic blocks.
870 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
871 that are otherwise unreachable may be reachable with a non-local goto.
873 BB_EH_END is an array indexed by basic block number in which we record
874 the list of exception regions active at the end of the basic block. */
877 make_edges (label_value_list)
878 rtx label_value_list;
881 eh_nesting_info *eh_nest_info = init_eh_nesting_info ();
882 sbitmap *edge_cache = NULL;
884 /* Assume no computed jump; revise as we create edges. */
885 current_function_has_computed_jump = 0;
887 /* Heavy use of computed goto in machine-generated code can lead to
888 nearly fully-connected CFGs. In that case we spend a significant
889 amount of time searching the edge lists for duplicates. */
890 if (forced_labels || label_value_list)
892 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
893 sbitmap_vector_zero (edge_cache, n_basic_blocks);
896 /* By nature of the way these get numbered, block 0 is always the entry. */
897 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
899 for (i = 0; i < n_basic_blocks; ++i)
901 basic_block bb = BASIC_BLOCK (i);
904 int force_fallthru = 0;
906 /* Examine the last instruction of the block, and discover the
907 ways we can leave the block. */
910 code = GET_CODE (insn);
913 if (code == JUMP_INSN)
917 /* ??? Recognize a tablejump and do the right thing. */
918 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
919 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
920 && GET_CODE (tmp) == JUMP_INSN
921 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
922 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
927 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
928 vec = XVEC (PATTERN (tmp), 0);
930 vec = XVEC (PATTERN (tmp), 1);
932 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
933 make_label_edge (edge_cache, bb,
934 XEXP (RTVEC_ELT (vec, j), 0), 0);
936 /* Some targets (eg, ARM) emit a conditional jump that also
937 contains the out-of-range target. Scan for these and
938 add an edge if necessary. */
939 if ((tmp = single_set (insn)) != NULL
940 && SET_DEST (tmp) == pc_rtx
941 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
942 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
943 make_label_edge (edge_cache, bb,
944 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
946 #ifdef CASE_DROPS_THROUGH
947 /* Silly VAXen. The ADDR_VEC is going to be in the way of
948 us naturally detecting fallthru into the next block. */
953 /* If this is a computed jump, then mark it as reaching
954 everything on the label_value_list and forced_labels list. */
955 else if (computed_jump_p (insn))
957 current_function_has_computed_jump = 1;
959 for (x = label_value_list; x; x = XEXP (x, 1))
960 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
962 for (x = forced_labels; x; x = XEXP (x, 1))
963 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
966 /* Returns create an exit out. */
967 else if (returnjump_p (insn))
968 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
970 /* Otherwise, we have a plain conditional or unconditional jump. */
973 if (! JUMP_LABEL (insn))
975 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
979 /* If this is a CALL_INSN, then mark it as reaching the active EH
980 handler for this CALL_INSN. If we're handling asynchronous
981 exceptions then any insn can reach any of the active handlers.
983 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
985 if (code == CALL_INSN || asynchronous_exceptions)
987 /* If there's an EH region active at the end of a block,
988 add the appropriate edges. */
990 make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end);
992 /* If we have asynchronous exceptions, do the same for *all*
993 exception regions active in the block. */
994 if (asynchronous_exceptions
995 && bb->eh_beg != bb->eh_end)
998 make_eh_edge (edge_cache, eh_nest_info, bb,
999 NULL_RTX, bb->eh_beg);
1001 for (x = bb->head; x != bb->end; x = NEXT_INSN (x))
1002 if (GET_CODE (x) == NOTE
1003 && (NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_BEG
1004 || NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_END))
1006 int region = NOTE_EH_HANDLER (x);
1007 make_eh_edge (edge_cache, eh_nest_info, bb,
1012 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1014 /* ??? This could be made smarter: in some cases it's possible
1015 to tell that certain calls will not do a nonlocal goto.
1017 For example, if the nested functions that do the nonlocal
1018 gotos do not have their addresses taken, then only calls to
1019 those functions or to other nested functions that use them
1020 could possibly do nonlocal gotos. */
1021 /* We do know that a REG_EH_REGION note with a value less
1022 than 0 is guaranteed not to perform a non-local goto. */
1023 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1024 if (!note || XINT (XEXP (note, 0), 0) >= 0)
1025 for (x = nonlocal_goto_handler_labels; x ; x = XEXP (x, 1))
1026 make_label_edge (edge_cache, bb, XEXP (x, 0),
1027 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1031 /* We know something about the structure of the function __throw in
1032 libgcc2.c. It is the only function that ever contains eh_stub
1033 labels. It modifies its return address so that the last block
1034 returns to one of the eh_stub labels within it. So we have to
1035 make additional edges in the flow graph. */
1036 if (i + 1 == n_basic_blocks && eh_return_stub_label != 0)
1037 make_label_edge (edge_cache, bb, eh_return_stub_label, EDGE_EH);
1039 /* Find out if we can drop through to the next block. */
1040 insn = next_nonnote_insn (insn);
1041 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1042 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1043 else if (i + 1 < n_basic_blocks)
1045 rtx tmp = BLOCK_HEAD (i + 1);
1046 if (GET_CODE (tmp) == NOTE)
1047 tmp = next_nonnote_insn (tmp);
1048 if (force_fallthru || insn == tmp)
1049 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1053 free_eh_nesting_info (eh_nest_info);
1055 sbitmap_vector_free (edge_cache);
1058 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1059 about the edge that is accumulated between calls. */
1062 make_edge (edge_cache, src, dst, flags)
1063 sbitmap *edge_cache;
1064 basic_block src, dst;
1070 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1071 many edges to them, and we didn't allocate memory for it. */
1072 use_edge_cache = (edge_cache
1073 && src != ENTRY_BLOCK_PTR
1074 && dst != EXIT_BLOCK_PTR);
1076 /* Make sure we don't add duplicate edges. */
1077 if (! use_edge_cache || TEST_BIT (edge_cache[src->index], dst->index))
1078 for (e = src->succ; e ; e = e->succ_next)
1085 e = (edge) xcalloc (1, sizeof (*e));
1088 e->succ_next = src->succ;
1089 e->pred_next = dst->pred;
1098 SET_BIT (edge_cache[src->index], dst->index);
1101 /* Create an edge from a basic block to a label. */
1104 make_label_edge (edge_cache, src, label, flags)
1105 sbitmap *edge_cache;
1110 if (GET_CODE (label) != CODE_LABEL)
1113 /* If the label was never emitted, this insn is junk, but avoid a
1114 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1115 as a result of a syntax error and a diagnostic has already been
1118 if (INSN_UID (label) == 0)
1121 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1124 /* Create the edges generated by INSN in REGION. */
1127 make_eh_edge (edge_cache, eh_nest_info, src, insn, region)
1128 sbitmap *edge_cache;
1129 eh_nesting_info *eh_nest_info;
1134 handler_info **handler_list;
1137 is_call = (insn && GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1138 num = reachable_handlers (region, eh_nest_info, insn, &handler_list);
1141 make_label_edge (edge_cache, src, handler_list[num]->handler_label,
1142 EDGE_ABNORMAL | EDGE_EH | is_call);
1146 /* EH_REGION notes appearing between basic blocks is ambiguous, and even
1147 dangerous if we intend to move basic blocks around. Move such notes
1148 into the following block. */
1151 move_stray_eh_region_notes ()
1156 if (n_basic_blocks < 2)
1159 b2 = BASIC_BLOCK (n_basic_blocks - 1);
1160 for (i = n_basic_blocks - 2; i >= 0; --i, b2 = b1)
1162 rtx insn, next, list = NULL_RTX;
1164 b1 = BASIC_BLOCK (i);
1165 for (insn = NEXT_INSN (b1->end); insn != b2->head; insn = next)
1167 next = NEXT_INSN (insn);
1168 if (GET_CODE (insn) == NOTE
1169 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1170 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1172 /* Unlink from the insn chain. */
1173 NEXT_INSN (PREV_INSN (insn)) = next;
1174 PREV_INSN (next) = PREV_INSN (insn);
1177 NEXT_INSN (insn) = list;
1182 if (list == NULL_RTX)
1185 /* Find where to insert these things. */
1187 if (GET_CODE (insn) == CODE_LABEL)
1188 insn = NEXT_INSN (insn);
1192 next = NEXT_INSN (list);
1193 add_insn_after (list, insn);
1199 /* Recompute eh_beg/eh_end for each basic block. */
1202 record_active_eh_regions (f)
1205 rtx insn, eh_list = NULL_RTX;
1207 basic_block bb = BASIC_BLOCK (0);
1209 for (insn = f; insn ; insn = NEXT_INSN (insn))
1211 if (bb->head == insn)
1212 bb->eh_beg = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1214 if (GET_CODE (insn) == NOTE)
1216 int kind = NOTE_LINE_NUMBER (insn);
1217 if (kind == NOTE_INSN_EH_REGION_BEG)
1218 eh_list = alloc_INSN_LIST (insn, eh_list);
1219 else if (kind == NOTE_INSN_EH_REGION_END)
1221 rtx t = XEXP (eh_list, 1);
1222 free_INSN_LIST_node (eh_list);
1227 if (bb->end == insn)
1229 bb->eh_end = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1231 if (i == n_basic_blocks)
1233 bb = BASIC_BLOCK (i);
1238 /* Identify critical edges and set the bits appropriately. */
1241 mark_critical_edges ()
1243 int i, n = n_basic_blocks;
1246 /* We begin with the entry block. This is not terribly important now,
1247 but could be if a front end (Fortran) implemented alternate entry
1249 bb = ENTRY_BLOCK_PTR;
1256 /* (1) Critical edges must have a source with multiple successors. */
1257 if (bb->succ && bb->succ->succ_next)
1259 for (e = bb->succ; e ; e = e->succ_next)
1261 /* (2) Critical edges must have a destination with multiple
1262 predecessors. Note that we know there is at least one
1263 predecessor -- the edge we followed to get here. */
1264 if (e->dest->pred->pred_next)
1265 e->flags |= EDGE_CRITICAL;
1267 e->flags &= ~EDGE_CRITICAL;
1272 for (e = bb->succ; e ; e = e->succ_next)
1273 e->flags &= ~EDGE_CRITICAL;
1278 bb = BASIC_BLOCK (i);
1282 /* Split a (typically critical) edge. Return the new block.
1283 Abort on abnormal edges.
1285 ??? The code generally expects to be called on critical edges.
1286 The case of a block ending in an unconditional jump to a
1287 block with multiple predecessors is not handled optimally. */
1290 split_edge (edge_in)
1293 basic_block old_pred, bb, old_succ;
1298 /* Abnormal edges cannot be split. */
1299 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1302 old_pred = edge_in->src;
1303 old_succ = edge_in->dest;
1305 /* Remove the existing edge from the destination's pred list. */
1308 for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next)
1310 *pp = edge_in->pred_next;
1311 edge_in->pred_next = NULL;
1314 /* Create the new structures. */
1315 bb = (basic_block) obstack_alloc (function_obstack, sizeof (*bb));
1316 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
1319 memset (bb, 0, sizeof (*bb));
1320 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
1321 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
1323 /* ??? This info is likely going to be out of date very soon. */
1324 if (old_succ->global_live_at_start)
1326 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
1327 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
1331 CLEAR_REG_SET (bb->global_live_at_start);
1332 CLEAR_REG_SET (bb->global_live_at_end);
1337 bb->succ = edge_out;
1340 edge_in->flags &= ~EDGE_CRITICAL;
1342 edge_out->pred_next = old_succ->pred;
1343 edge_out->succ_next = NULL;
1345 edge_out->dest = old_succ;
1346 edge_out->flags = EDGE_FALLTHRU;
1347 edge_out->probability = REG_BR_PROB_BASE;
1349 old_succ->pred = edge_out;
1351 /* Tricky case -- if there existed a fallthru into the successor
1352 (and we're not it) we must add a new unconditional jump around
1353 the new block we're actually interested in.
1355 Further, if that edge is critical, this means a second new basic
1356 block must be created to hold it. In order to simplify correct
1357 insn placement, do this before we touch the existing basic block
1358 ordering for the block we were really wanting. */
1359 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1362 for (e = edge_out->pred_next; e ; e = e->pred_next)
1363 if (e->flags & EDGE_FALLTHRU)
1368 basic_block jump_block;
1371 if ((e->flags & EDGE_CRITICAL) == 0)
1373 /* Non critical -- we can simply add a jump to the end
1374 of the existing predecessor. */
1375 jump_block = e->src;
1379 /* We need a new block to hold the jump. The simplest
1380 way to do the bulk of the work here is to recursively
1382 jump_block = split_edge (e);
1383 e = jump_block->succ;
1386 /* Now add the jump insn ... */
1387 pos = emit_jump_insn_after (gen_jump (old_succ->head),
1389 jump_block->end = pos;
1390 emit_barrier_after (pos);
1392 /* ... let jump know that label is in use, ... */
1393 JUMP_LABEL (pos) = old_succ->head;
1394 ++LABEL_NUSES (old_succ->head);
1396 /* ... and clear fallthru on the outgoing edge. */
1397 e->flags &= ~EDGE_FALLTHRU;
1399 /* Continue splitting the interesting edge. */
1403 /* Place the new block just in front of the successor. */
1404 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1405 if (old_succ == EXIT_BLOCK_PTR)
1406 j = n_basic_blocks - 1;
1408 j = old_succ->index;
1409 for (i = n_basic_blocks - 1; i > j; --i)
1411 basic_block tmp = BASIC_BLOCK (i - 1);
1412 BASIC_BLOCK (i) = tmp;
1415 BASIC_BLOCK (i) = bb;
1418 /* Create the basic block note.
1420 Where we place the note can have a noticable impact on the generated
1421 code. Consider this cfg:
1432 If we need to insert an insn on the edge from block 0 to block 1,
1433 we want to ensure the instructions we insert are outside of any
1434 loop notes that physically sit between block 0 and block 1. Otherwise
1435 we confuse the loop optimizer into thinking the loop is a phony. */
1436 if (old_succ != EXIT_BLOCK_PTR
1437 && PREV_INSN (old_succ->head)
1438 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
1439 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
1440 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1441 PREV_INSN (old_succ->head));
1442 else if (old_succ != EXIT_BLOCK_PTR)
1443 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
1445 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
1446 NOTE_BASIC_BLOCK (bb_note) = bb;
1447 bb->head = bb->end = bb_note;
1449 /* Not quite simple -- for non-fallthru edges, we must adjust the
1450 predecessor's jump instruction to target our new block. */
1451 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1453 rtx tmp, insn = old_pred->end;
1454 rtx old_label = old_succ->head;
1455 rtx new_label = gen_label_rtx ();
1457 if (GET_CODE (insn) != JUMP_INSN)
1460 /* ??? Recognize a tablejump and adjust all matching cases. */
1461 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1462 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1463 && GET_CODE (tmp) == JUMP_INSN
1464 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1465 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1470 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1471 vec = XVEC (PATTERN (tmp), 0);
1473 vec = XVEC (PATTERN (tmp), 1);
1475 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1476 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1478 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
1479 --LABEL_NUSES (old_label);
1480 ++LABEL_NUSES (new_label);
1483 /* Handle casesi dispatch insns */
1484 if ((tmp = single_set (insn)) != NULL
1485 && SET_DEST (tmp) == pc_rtx
1486 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1487 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1488 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1490 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1492 --LABEL_NUSES (old_label);
1493 ++LABEL_NUSES (new_label);
1498 /* This would have indicated an abnormal edge. */
1499 if (computed_jump_p (insn))
1502 /* A return instruction can't be redirected. */
1503 if (returnjump_p (insn))
1506 /* If the insn doesn't go where we think, we're confused. */
1507 if (JUMP_LABEL (insn) != old_label)
1510 redirect_jump (insn, new_label);
1513 emit_label_before (new_label, bb_note);
1514 bb->head = new_label;
1520 /* Queue instructions for insertion on an edge between two basic blocks.
1521 The new instructions and basic blocks (if any) will not appear in the
1522 CFG until commit_edge_insertions is called. */
1525 insert_insn_on_edge (pattern, e)
1529 /* We cannot insert instructions on an abnormal critical edge.
1530 It will be easier to find the culprit if we die now. */
1531 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
1532 == (EDGE_ABNORMAL|EDGE_CRITICAL))
1535 if (e->insns == NULL_RTX)
1538 push_to_sequence (e->insns);
1540 emit_insn (pattern);
1542 e->insns = get_insns ();
1546 /* Update the CFG for the instructions queued on edge E. */
1549 commit_one_edge_insertion (e)
1552 rtx before = NULL_RTX, after = NULL_RTX, tmp;
1555 /* Figure out where to put these things. If the destination has
1556 one predecessor, insert there. Except for the exit block. */
1557 if (e->dest->pred->pred_next == NULL
1558 && e->dest != EXIT_BLOCK_PTR)
1562 /* Get the location correct wrt a code label, and "nice" wrt
1563 a basic block note, and before everything else. */
1565 if (GET_CODE (tmp) == CODE_LABEL)
1566 tmp = NEXT_INSN (tmp);
1567 if (GET_CODE (tmp) == NOTE
1568 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_BASIC_BLOCK)
1569 tmp = NEXT_INSN (tmp);
1570 if (tmp == bb->head)
1573 after = PREV_INSN (tmp);
1576 /* If the source has one successor and the edge is not abnormal,
1577 insert there. Except for the entry block. */
1578 else if ((e->flags & EDGE_ABNORMAL) == 0
1579 && e->src->succ->succ_next == NULL
1580 && e->src != ENTRY_BLOCK_PTR)
1583 if (GET_CODE (bb->end) == JUMP_INSN)
1585 /* ??? Is it possible to wind up with non-simple jumps? Perhaps
1586 a jump with delay slots already filled? */
1587 if (! simplejump_p (bb->end))
1594 /* We'd better be fallthru, or we've lost track of what's what. */
1595 if ((e->flags & EDGE_FALLTHRU) == 0)
1602 /* Otherwise we must split the edge. */
1605 bb = split_edge (e);
1609 /* Now that we've found the spot, do the insertion. */
1611 e->insns = NULL_RTX;
1613 /* Set the new block number for these insns, if structure is allocated. */
1614 if (basic_block_for_insn)
1617 for (i = tmp; i != NULL_RTX; i = NEXT_INSN (i))
1618 set_block_for_insn (i, bb);
1623 emit_insns_before (tmp, before);
1624 if (before == bb->head)
1629 tmp = emit_insns_after (tmp, after);
1630 if (after == bb->end)
1635 /* Update the CFG for all queued instructions. */
1638 commit_edge_insertions ()
1644 bb = ENTRY_BLOCK_PTR;
1649 for (e = bb->succ; e ; e = next)
1651 next = e->succ_next;
1653 commit_one_edge_insertion (e);
1656 if (++i >= n_basic_blocks)
1658 bb = BASIC_BLOCK (i);
1662 /* Delete all unreachable basic blocks. */
1665 delete_unreachable_blocks ()
1667 basic_block *worklist, *tos;
1668 int deleted_handler;
1673 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
1675 /* Use basic_block->aux as a marker. Clear them all. */
1677 for (i = 0; i < n; ++i)
1678 BASIC_BLOCK (i)->aux = NULL;
1680 /* Add our starting points to the worklist. Almost always there will
1681 be only one. It isn't inconcievable that we might one day directly
1682 support Fortran alternate entry points. */
1684 for (e = ENTRY_BLOCK_PTR->succ; e ; e = e->succ_next)
1688 /* Mark the block with a handy non-null value. */
1692 /* Iterate: find everything reachable from what we've already seen. */
1694 while (tos != worklist)
1696 basic_block b = *--tos;
1698 for (e = b->succ; e ; e = e->succ_next)
1706 /* Delete all unreachable basic blocks. Count down so that we don't
1707 interfere with the block renumbering that happens in delete_block. */
1709 deleted_handler = 0;
1711 for (i = n - 1; i >= 0; --i)
1713 basic_block b = BASIC_BLOCK (i);
1716 /* This block was found. Tidy up the mark. */
1719 deleted_handler |= delete_block (b);
1722 /* Fix up edges that now fall through, or rather should now fall through
1723 but previously required a jump around now deleted blocks. Simplify
1724 the search by only examining blocks numerically adjacent, since this
1725 is how find_basic_blocks created them. */
1727 for (i = 1; i < n_basic_blocks; ++i)
1729 basic_block b = BASIC_BLOCK (i - 1);
1730 basic_block c = BASIC_BLOCK (i);
1733 /* We care about simple conditional or unconditional jumps with
1736 If we had a conditional branch to the next instruction when
1737 find_basic_blocks was called, then there will only be one
1738 out edge for the block which ended with the conditional
1739 branch (since we do not create duplicate edges).
1741 Furthermore, the edge will be marked as a fallthru because we
1742 merge the flags for the duplicate edges. So we do not want to
1743 check that the edge is not a FALLTHRU edge. */
1744 if ((s = b->succ) != NULL
1745 && s->succ_next == NULL
1747 /* If the jump insn has side effects, we can't tidy the edge. */
1748 && (GET_CODE (b->end) != JUMP_INSN
1749 || onlyjump_p (b->end)))
1750 tidy_fallthru_edge (s, b, c);
1753 /* If we deleted an exception handler, we may have EH region begin/end
1754 blocks to remove as well. */
1755 if (deleted_handler)
1756 delete_eh_regions ();
1761 /* Find EH regions for which there is no longer a handler, and delete them. */
1764 delete_eh_regions ()
1768 update_rethrow_references ();
1770 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
1771 if (GET_CODE (insn) == NOTE)
1773 if ((NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) ||
1774 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1776 int num = NOTE_EH_HANDLER (insn);
1777 /* A NULL handler indicates a region is no longer needed,
1778 as long as it isn't the target of a rethrow. */
1779 if (get_first_handler (num) == NULL && ! rethrow_used (num))
1781 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1782 NOTE_SOURCE_FILE (insn) = 0;
1788 /* Return true if NOTE is not one of the ones that must be kept paired,
1789 so that we may simply delete them. */
1792 can_delete_note_p (note)
1795 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
1796 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
1799 /* Unlink a chain of insns between START and FINISH, leaving notes
1800 that must be paired. */
1803 flow_delete_insn_chain (start, finish)
1806 /* Unchain the insns one by one. It would be quicker to delete all
1807 of these with a single unchaining, rather than one at a time, but
1808 we need to keep the NOTE's. */
1814 next = NEXT_INSN (start);
1815 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
1817 else if (GET_CODE (start) == CODE_LABEL && !can_delete_label_p (start))
1820 next = flow_delete_insn (start);
1822 if (start == finish)
1828 /* Delete the insns in a (non-live) block. We physically delete every
1829 non-deleted-note insn, and update the flow graph appropriately.
1831 Return nonzero if we deleted an exception handler. */
1833 /* ??? Preserving all such notes strikes me as wrong. It would be nice
1834 to post-process the stream to remove empty blocks, loops, ranges, etc. */
1840 int deleted_handler = 0;
1843 /* If the head of this block is a CODE_LABEL, then it might be the
1844 label for an exception handler which can't be reached.
1846 We need to remove the label from the exception_handler_label list
1847 and remove the associated NOTE_INSN_EH_REGION_BEG and
1848 NOTE_INSN_EH_REGION_END notes. */
1852 never_reached_warning (insn);
1854 if (GET_CODE (insn) == CODE_LABEL)
1856 rtx x, *prev = &exception_handler_labels;
1858 for (x = exception_handler_labels; x; x = XEXP (x, 1))
1860 if (XEXP (x, 0) == insn)
1862 /* Found a match, splice this label out of the EH label list. */
1863 *prev = XEXP (x, 1);
1864 XEXP (x, 1) = NULL_RTX;
1865 XEXP (x, 0) = NULL_RTX;
1867 /* Remove the handler from all regions */
1868 remove_handler (insn);
1869 deleted_handler = 1;
1872 prev = &XEXP (x, 1);
1875 /* This label may be referenced by code solely for its value, or
1876 referenced by static data, or something. We have determined
1877 that it is not reachable, but cannot delete the label itself.
1878 Save code space and continue to delete the balance of the block,
1879 along with properly updating the cfg. */
1880 if (!can_delete_label_p (insn))
1882 /* If we've only got one of these, skip the whole deleting
1885 goto no_delete_insns;
1886 insn = NEXT_INSN (insn);
1890 /* Selectively unlink the insn chain. Include any BARRIER that may
1891 follow the basic block. */
1892 end = next_nonnote_insn (b->end);
1893 if (!end || GET_CODE (end) != BARRIER)
1895 flow_delete_insn_chain (insn, end);
1899 /* Remove the edges into and out of this block. Note that there may
1900 indeed be edges in, if we are removing an unreachable loop. */
1904 for (e = b->pred; e ; e = next)
1906 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
1909 next = e->pred_next;
1913 for (e = b->succ; e ; e = next)
1915 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
1918 next = e->succ_next;
1927 /* Remove the basic block from the array, and compact behind it. */
1930 return deleted_handler;
1933 /* Remove block B from the basic block array and compact behind it. */
1939 int i, n = n_basic_blocks;
1941 for (i = b->index; i + 1 < n; ++i)
1943 basic_block x = BASIC_BLOCK (i + 1);
1944 BASIC_BLOCK (i) = x;
1948 basic_block_info->num_elements--;
1952 /* Delete INSN by patching it out. Return the next insn. */
1955 flow_delete_insn (insn)
1958 rtx prev = PREV_INSN (insn);
1959 rtx next = NEXT_INSN (insn);
1961 PREV_INSN (insn) = NULL_RTX;
1962 NEXT_INSN (insn) = NULL_RTX;
1965 NEXT_INSN (prev) = next;
1967 PREV_INSN (next) = prev;
1969 set_last_insn (prev);
1971 if (GET_CODE (insn) == CODE_LABEL)
1972 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
1974 /* If deleting a jump, decrement the use count of the label. Deleting
1975 the label itself should happen in the normal course of block merging. */
1976 if (GET_CODE (insn) == JUMP_INSN && JUMP_LABEL (insn))
1977 LABEL_NUSES (JUMP_LABEL (insn))--;
1982 /* True if a given label can be deleted. */
1985 can_delete_label_p (label)
1990 if (LABEL_PRESERVE_P (label))
1993 for (x = forced_labels; x ; x = XEXP (x, 1))
1994 if (label == XEXP (x, 0))
1996 for (x = label_value_list; x ; x = XEXP (x, 1))
1997 if (label == XEXP (x, 0))
1999 for (x = exception_handler_labels; x ; x = XEXP (x, 1))
2000 if (label == XEXP (x, 0))
2003 /* User declared labels must be preserved. */
2004 if (LABEL_NAME (label) != 0)
2010 /* Blocks A and B are to be merged into a single block. A has no incoming
2011 fallthru edge, so it can be moved before B without adding or modifying
2012 any jumps (aside from the jump from A to B). */
2015 merge_blocks_move_predecessor_nojumps (a, b)
2018 rtx start, end, barrier;
2024 /* We want to delete the BARRIER after the end of the insns we are
2025 going to move. If we don't find a BARRIER, then do nothing. This
2026 can happen in some cases if we have labels we can not delete.
2028 Similarly, do nothing if we can not delete the label at the start
2029 of the target block. */
2030 barrier = next_nonnote_insn (end);
2031 if (GET_CODE (barrier) != BARRIER
2032 || (GET_CODE (b->head) == CODE_LABEL
2033 && ! can_delete_label_p (b->head)))
2036 flow_delete_insn (barrier);
2038 /* Move block and loop notes out of the chain so that we do not
2039 disturb their order.
2041 ??? A better solution would be to squeeze out all the non-nested notes
2042 and adjust the block trees appropriately. Even better would be to have
2043 a tighter connection between block trees and rtl so that this is not
2045 start = squeeze_notes (start, end);
2047 /* Scramble the insn chain. */
2048 if (end != PREV_INSN (b->head))
2049 reorder_insns (start, end, PREV_INSN (b->head));
2053 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2054 a->index, b->index);
2057 /* Swap the records for the two blocks around. Although we are deleting B,
2058 A is now where B was and we want to compact the BB array from where
2060 BASIC_BLOCK(a->index) = b;
2061 BASIC_BLOCK(b->index) = a;
2063 a->index = b->index;
2066 /* Now blocks A and B are contiguous. Merge them. */
2067 merge_blocks_nomove (a, b);
2072 /* Blocks A and B are to be merged into a single block. B has no outgoing
2073 fallthru edge, so it can be moved after A without adding or modifying
2074 any jumps (aside from the jump from A to B). */
2077 merge_blocks_move_successor_nojumps (a, b)
2080 rtx start, end, barrier;
2085 /* We want to delete the BARRIER after the end of the insns we are
2086 going to move. If we don't find a BARRIER, then do nothing. This
2087 can happen in some cases if we have labels we can not delete.
2089 Similarly, do nothing if we can not delete the label at the start
2090 of the target block. */
2091 barrier = next_nonnote_insn (end);
2092 if (GET_CODE (barrier) != BARRIER
2093 || (GET_CODE (b->head) == CODE_LABEL
2094 && ! can_delete_label_p (b->head)))
2097 flow_delete_insn (barrier);
2099 /* Move block and loop notes out of the chain so that we do not
2100 disturb their order.
2102 ??? A better solution would be to squeeze out all the non-nested notes
2103 and adjust the block trees appropriately. Even better would be to have
2104 a tighter connection between block trees and rtl so that this is not
2106 start = squeeze_notes (start, end);
2108 /* Scramble the insn chain. */
2109 reorder_insns (start, end, a->end);
2111 /* Now blocks A and B are contiguous. Merge them. */
2112 merge_blocks_nomove (a, b);
2116 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2117 b->index, a->index);
2123 /* Blocks A and B are to be merged into a single block. The insns
2124 are already contiguous, hence `nomove'. */
2127 merge_blocks_nomove (a, b)
2131 rtx b_head, b_end, a_end;
2134 /* If there was a CODE_LABEL beginning B, delete it. */
2137 if (GET_CODE (b_head) == CODE_LABEL)
2139 /* Detect basic blocks with nothing but a label. This can happen
2140 in particular at the end of a function. */
2141 if (b_head == b_end)
2143 b_head = flow_delete_insn (b_head);
2146 /* Delete the basic block note. */
2147 if (GET_CODE (b_head) == NOTE
2148 && NOTE_LINE_NUMBER (b_head) == NOTE_INSN_BASIC_BLOCK)
2150 if (b_head == b_end)
2152 b_head = flow_delete_insn (b_head);
2155 /* If there was a jump out of A, delete it. */
2157 if (GET_CODE (a_end) == JUMP_INSN)
2161 prev = prev_nonnote_insn (a_end);
2166 /* If this was a conditional jump, we need to also delete
2167 the insn that set cc0. */
2169 if (prev && sets_cc0_p (prev))
2172 prev = prev_nonnote_insn (prev);
2175 flow_delete_insn (tmp);
2179 /* Note that a->head != a->end, since we should have at least a
2180 bb note plus the jump, so prev != insn. */
2181 flow_delete_insn (a_end);
2185 /* By definition, there should only be one successor of A, and that is
2186 B. Free that edge struct. */
2190 /* Adjust the edges out of B for the new owner. */
2191 for (e = b->succ; e ; e = e->succ_next)
2195 /* Reassociate the insns of B with A. */
2198 BLOCK_FOR_INSN (b_head) = a;
2199 while (b_head != b_end)
2201 b_head = NEXT_INSN (b_head);
2202 BLOCK_FOR_INSN (b_head) = a;
2208 /* Compact the basic block array. */
2212 /* Attempt to merge basic blocks that are potentially non-adjacent.
2213 Return true iff the attempt succeeded. */
2216 merge_blocks (e, b, c)
2220 /* If B has a fallthru edge to C, no need to move anything. */
2221 if (e->flags & EDGE_FALLTHRU)
2223 /* If a label still appears somewhere and we cannot delete the label,
2224 then we cannot merge the blocks. The edge was tidied already. */
2226 rtx insn, stop = NEXT_INSN (c->head);
2227 for (insn = NEXT_INSN (b->end); insn != stop; insn = NEXT_INSN (insn))
2228 if (GET_CODE (insn) == CODE_LABEL && !can_delete_label_p (insn))
2231 merge_blocks_nomove (b, c);
2235 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2236 b->index, c->index);
2245 int c_has_outgoing_fallthru;
2246 int b_has_incoming_fallthru;
2248 /* We must make sure to not munge nesting of exception regions,
2249 lexical blocks, and loop notes.
2251 The first is taken care of by requiring that the active eh
2252 region at the end of one block always matches the active eh
2253 region at the beginning of the next block.
2255 The later two are taken care of by squeezing out all the notes. */
2257 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2258 executed and we may want to treat blocks which have two out
2259 edges, one normal, one abnormal as only having one edge for
2260 block merging purposes. */
2262 for (tmp_edge = c->succ; tmp_edge ; tmp_edge = tmp_edge->succ_next)
2263 if (tmp_edge->flags & EDGE_FALLTHRU)
2265 c_has_outgoing_fallthru = (tmp_edge != NULL);
2267 for (tmp_edge = b->pred; tmp_edge ; tmp_edge = tmp_edge->pred_next)
2268 if (tmp_edge->flags & EDGE_FALLTHRU)
2270 b_has_incoming_fallthru = (tmp_edge != NULL);
2272 /* If B does not have an incoming fallthru, and the exception regions
2273 match, then it can be moved immediately before C without introducing
2276 C can not be the first block, so we do not have to worry about
2277 accessing a non-existent block. */
2278 d = BASIC_BLOCK (c->index - 1);
2279 if (! b_has_incoming_fallthru
2280 && d->eh_end == b->eh_beg
2281 && b->eh_end == c->eh_beg)
2282 return merge_blocks_move_predecessor_nojumps (b, c);
2284 /* Otherwise, we're going to try to move C after B. Make sure the
2285 exception regions match.
2287 If B is the last basic block, then we must not try to access the
2288 block structure for block B + 1. Luckily in that case we do not
2289 need to worry about matching exception regions. */
2290 d = (b->index + 1 < n_basic_blocks ? BASIC_BLOCK (b->index + 1) : NULL);
2291 if (b->eh_end == c->eh_beg
2292 && (d == NULL || c->eh_end == d->eh_beg))
2294 /* If C does not have an outgoing fallthru, then it can be moved
2295 immediately after B without introducing or modifying jumps. */
2296 if (! c_has_outgoing_fallthru)
2297 return merge_blocks_move_successor_nojumps (b, c);
2299 /* Otherwise, we'll need to insert an extra jump, and possibly
2300 a new block to contain it. */
2301 /* ??? Not implemented yet. */
2308 /* Top level driver for merge_blocks. */
2315 /* Attempt to merge blocks as made possible by edge removal. If a block
2316 has only one successor, and the successor has only one predecessor,
2317 they may be combined. */
2319 for (i = 0; i < n_basic_blocks; )
2321 basic_block c, b = BASIC_BLOCK (i);
2324 /* A loop because chains of blocks might be combineable. */
2325 while ((s = b->succ) != NULL
2326 && s->succ_next == NULL
2327 && (s->flags & EDGE_EH) == 0
2328 && (c = s->dest) != EXIT_BLOCK_PTR
2329 && c->pred->pred_next == NULL
2330 /* If the jump insn has side effects, we can't kill the edge. */
2331 && (GET_CODE (b->end) != JUMP_INSN
2332 || onlyjump_p (b->end))
2333 && merge_blocks (s, b, c))
2336 /* Don't get confused by the index shift caused by deleting blocks. */
2341 /* The given edge should potentially a fallthru edge. If that is in
2342 fact true, delete the unconditional jump and barriers that are in
2346 tidy_fallthru_edge (e, b, c)
2352 /* ??? In a late-running flow pass, other folks may have deleted basic
2353 blocks by nopping out blocks, leaving multiple BARRIERs between here
2354 and the target label. They ought to be chastized and fixed.
2356 We can also wind up with a sequence of undeletable labels between
2357 one block and the next.
2359 So search through a sequence of barriers, labels, and notes for
2360 the head of block C and assert that we really do fall through. */
2362 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
2365 /* Remove what will soon cease being the jump insn from the source block.
2366 If block B consisted only of this single jump, turn it into a deleted
2369 if (GET_CODE (q) == JUMP_INSN)
2372 /* If this was a conditional jump, we need to also delete
2373 the insn that set cc0. */
2374 if (! simplejump_p (q) && condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
2381 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
2382 NOTE_SOURCE_FILE (q) = 0;
2385 b->end = q = PREV_INSN (q);
2388 /* Selectively unlink the sequence. */
2389 if (q != PREV_INSN (c->head))
2390 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
2392 e->flags |= EDGE_FALLTHRU;
2395 /* Discover and record the loop depth at the head of each basic block. */
2398 calculate_loop_depth (dump)
2403 /* The loop infrastructure does the real job for us. */
2404 flow_loops_find (&loops);
2407 flow_loops_dump (&loops, dump, 0);
2409 flow_loops_free (&loops);
2412 /* Perform data flow analysis.
2413 F is the first insn of the function and NREGS the number of register numbers
2417 life_analysis (f, nregs, file, remove_dead_code)
2421 int remove_dead_code;
2423 #ifdef ELIMINABLE_REGS
2425 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
2429 /* Record which registers will be eliminated. We use this in
2432 CLEAR_HARD_REG_SET (elim_reg_set);
2434 #ifdef ELIMINABLE_REGS
2435 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
2436 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
2438 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
2441 /* Allocate a bitmap to be filled in by record_volatile_insns. */
2442 uid_volatile = BITMAP_XMALLOC ();
2444 /* We want alias analysis information for local dead store elimination. */
2445 init_alias_analysis ();
2448 if (! remove_dead_code)
2449 flags &= ~(PROP_SCAN_DEAD_CODE | PROP_KILL_DEAD_CODE);
2450 life_analysis_1 (f, nregs, flags);
2452 if (! reload_completed)
2453 mark_constant_function ();
2455 end_alias_analysis ();
2458 dump_flow_info (file);
2460 BITMAP_XFREE (uid_volatile);
2461 free_basic_block_vars (1);
2464 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2465 Search for REGNO. If found, abort if it is not wider than word_mode. */
2468 verify_wide_reg_1 (px, pregno)
2473 int regno = *(int *) pregno;
2475 if (GET_CODE (x) == REG && REGNO (x) == regno)
2477 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
2484 /* A subroutine of verify_local_live_at_start. Search through insns
2485 between HEAD and END looking for register REGNO. */
2488 verify_wide_reg (regno, head, end)
2494 if (GET_RTX_CLASS (GET_CODE (head)) == 'i'
2495 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
2499 head = NEXT_INSN (head);
2502 /* We didn't find the register at all. Something's way screwy. */
2506 /* A subroutine of update_life_info. Verify that there are no untoward
2507 changes in live_at_start during a local update. */
2510 verify_local_live_at_start (new_live_at_start, bb)
2511 regset new_live_at_start;
2514 if (reload_completed)
2516 /* After reload, there are no pseudos, nor subregs of multi-word
2517 registers. The regsets should exactly match. */
2518 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
2525 /* Find the set of changed registers. */
2526 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
2528 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
2530 /* No registers should die. */
2531 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
2533 /* Verify that the now-live register is wider than word_mode. */
2534 verify_wide_reg (i, bb->head, bb->end);
2539 /* Updates death notes starting with the basic blocks set in BLOCKS.
2541 If LOCAL_ONLY, such as after splitting or peepholeing, we are only
2542 expecting local modifications to basic blocks. If we find extra
2543 registers live at the beginning of a block, then we either killed
2544 useful data, or we have a broken split that wants data not provided.
2545 If we find registers removed from live_at_start, that means we have
2546 a broken peephole that is killing a register it shouldn't.
2548 ??? This is not true in one situation -- when a pre-reload splitter
2549 generates subregs of a multi-word pseudo, current life analysis will
2550 lose the kill. So we _can_ have a pseudo go live. How irritating.
2552 BLOCK_FOR_INSN is assumed to be correct.
2554 ??? PROP_FLAGS should not contain PROP_LOG_LINKS. Need to set up
2555 reg_next_use for that. Including PROP_REG_INFO does not refresh
2556 regs_ever_live unless the caller resets it to zero. */
2559 update_life_info (blocks, extent, prop_flags)
2561 enum update_life_extent extent;
2567 tmp = ALLOCA_REG_SET ();
2569 /* For a global update, we go through the relaxation process again. */
2570 if (extent != UPDATE_LIFE_LOCAL)
2572 calculate_global_regs_live (blocks, blocks,
2573 prop_flags & PROP_SCAN_DEAD_CODE);
2575 /* If asked, remove notes from the blocks we'll update. */
2576 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
2577 count_or_remove_death_notes (blocks, 1);
2580 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2582 basic_block bb = BASIC_BLOCK (i);
2584 COPY_REG_SET (tmp, bb->global_live_at_end);
2585 propagate_block (tmp, bb->head, bb->end, (regset) NULL, i,
2588 if (extent == UPDATE_LIFE_LOCAL)
2589 verify_local_live_at_start (tmp, bb);
2595 /* Free the variables allocated by find_basic_blocks.
2597 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
2600 free_basic_block_vars (keep_head_end_p)
2601 int keep_head_end_p;
2603 if (basic_block_for_insn)
2605 VARRAY_FREE (basic_block_for_insn);
2606 basic_block_for_insn = NULL;
2609 if (! keep_head_end_p)
2612 VARRAY_FREE (basic_block_info);
2615 ENTRY_BLOCK_PTR->aux = NULL;
2616 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
2617 EXIT_BLOCK_PTR->aux = NULL;
2618 EXIT_BLOCK_PTR->global_live_at_start = NULL;
2622 /* Return nonzero if the destination of SET equals the source. */
2627 rtx src = SET_SRC (set);
2628 rtx dst = SET_DEST (set);
2629 if (GET_CODE (src) == REG && GET_CODE (dst) == REG
2630 && REGNO (src) == REGNO (dst))
2632 if (GET_CODE (src) != SUBREG || GET_CODE (dst) != SUBREG
2633 || SUBREG_WORD (src) != SUBREG_WORD (dst))
2635 src = SUBREG_REG (src);
2636 dst = SUBREG_REG (dst);
2637 if (GET_CODE (src) == REG && GET_CODE (dst) == REG
2638 && REGNO (src) == REGNO (dst))
2643 /* Return nonzero if an insn consists only of SETs, each of which only sets a
2649 rtx pat = PATTERN (insn);
2651 /* Insns carrying these notes are useful later on. */
2652 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
2655 if (GET_CODE (pat) == SET && set_noop_p (pat))
2658 if (GET_CODE (pat) == PARALLEL)
2661 /* If nothing but SETs of registers to themselves,
2662 this insn can also be deleted. */
2663 for (i = 0; i < XVECLEN (pat, 0); i++)
2665 rtx tem = XVECEXP (pat, 0, i);
2667 if (GET_CODE (tem) == USE
2668 || GET_CODE (tem) == CLOBBER)
2671 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
2681 notice_stack_pointer_modification (x, pat, data)
2683 rtx pat ATTRIBUTE_UNUSED;
2684 void *data ATTRIBUTE_UNUSED;
2686 if (x == stack_pointer_rtx
2687 /* The stack pointer is only modified indirectly as the result
2688 of a push until later in flow. See the comments in rtl.texi
2689 regarding Embedded Side-Effects on Addresses. */
2690 || (GET_CODE (x) == MEM
2691 && (GET_CODE (XEXP (x, 0)) == PRE_DEC
2692 || GET_CODE (XEXP (x, 0)) == PRE_INC
2693 || GET_CODE (XEXP (x, 0)) == POST_DEC
2694 || GET_CODE (XEXP (x, 0)) == POST_INC)
2695 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
2696 current_function_sp_is_unchanging = 0;
2699 /* Record which insns refer to any volatile memory
2700 or for any reason can't be deleted just because they are dead stores.
2701 Also, delete any insns that copy a register to itself.
2702 And see if the stack pointer is modified. */
2704 record_volatile_insns (f)
2708 for (insn = f; insn; insn = NEXT_INSN (insn))
2710 enum rtx_code code1 = GET_CODE (insn);
2711 if (code1 == CALL_INSN)
2712 SET_INSN_VOLATILE (insn);
2713 else if (code1 == INSN || code1 == JUMP_INSN)
2715 if (GET_CODE (PATTERN (insn)) != USE
2716 && volatile_refs_p (PATTERN (insn)))
2717 SET_INSN_VOLATILE (insn);
2719 /* A SET that makes space on the stack cannot be dead.
2720 (Such SETs occur only for allocating variable-size data,
2721 so they will always have a PLUS or MINUS according to the
2722 direction of stack growth.)
2723 Even if this function never uses this stack pointer value,
2724 signal handlers do! */
2725 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
2726 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
2727 #ifdef STACK_GROWS_DOWNWARD
2728 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
2730 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
2732 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
2733 SET_INSN_VOLATILE (insn);
2735 /* Delete (in effect) any obvious no-op moves. */
2736 else if (noop_move_p (insn))
2738 PUT_CODE (insn, NOTE);
2739 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2740 NOTE_SOURCE_FILE (insn) = 0;
2744 /* Check if insn modifies the stack pointer. */
2745 if ( current_function_sp_is_unchanging
2746 && GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2747 note_stores (PATTERN (insn),
2748 notice_stack_pointer_modification,
2753 /* Mark a register in SET. Hard registers in large modes get all
2754 of their component registers set as well. */
2760 int regno = REGNO (reg);
2762 SET_REGNO_REG_SET (set, regno);
2763 if (regno < FIRST_PSEUDO_REGISTER)
2765 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
2767 SET_REGNO_REG_SET (set, regno + n);
2771 /* Mark those regs which are needed at the end of the function as live
2772 at the end of the last basic block. */
2774 mark_regs_live_at_end (set)
2780 /* If exiting needs the right stack value, consider the stack pointer
2781 live at the end of the function. */
2782 if ((HAVE_epilogue && reload_completed)
2783 || ! EXIT_IGNORE_STACK
2784 || (! FRAME_POINTER_REQUIRED
2785 && ! current_function_calls_alloca
2786 && flag_omit_frame_pointer)
2787 || current_function_sp_is_unchanging)
2789 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
2792 /* Mark the frame pointer if needed at the end of the function. If
2793 we end up eliminating it, it will be removed from the live list
2794 of each basic block by reload. */
2796 if (! reload_completed || frame_pointer_needed)
2798 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
2799 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2800 /* If they are different, also mark the hard frame pointer as live */
2801 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
2805 #ifdef PIC_OFFSET_TABLE_REGNUM
2806 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
2807 /* Many architectures have a GP register even without flag_pic.
2808 Assume the pic register is not in use, or will be handled by
2809 other means, if it is not fixed. */
2810 if (fixed_regs[PIC_OFFSET_TABLE_REGNUM])
2811 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
2815 /* Mark all global registers, and all registers used by the epilogue
2816 as being live at the end of the function since they may be
2817 referenced by our caller. */
2818 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2820 #ifdef EPILOGUE_USES
2821 || EPILOGUE_USES (i)
2824 SET_REGNO_REG_SET (set, i);
2826 /* Mark all call-saved registers that we actaully used. */
2827 if (HAVE_epilogue && reload_completed)
2829 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2830 if (! call_used_regs[i] && regs_ever_live[i])
2831 SET_REGNO_REG_SET (set, i);
2834 /* Mark function return value. */
2835 /* ??? Only do this after reload. Consider a non-void function that
2836 omits a return statement. Across that edge we'll have the return
2837 register live, and no set for it. Thus the return register will
2838 be live back through the CFG to the entry, and thus we die. A
2839 possible solution is to emit a clobber at exits without returns. */
2841 type = TREE_TYPE (DECL_RESULT (current_function_decl));
2842 if (reload_completed
2843 && type != void_type_node)
2847 if (current_function_returns_struct
2848 || current_function_returns_pcc_struct)
2849 type = build_pointer_type (type);
2851 #ifdef FUNCTION_OUTGOING_VALUE
2852 outgoing = FUNCTION_OUTGOING_VALUE (type, current_function_decl);
2854 outgoing = FUNCTION_VALUE (type, current_function_decl);
2857 if (GET_CODE (outgoing) == REG)
2858 mark_reg (set, outgoing);
2859 else if (GET_CODE (outgoing) == PARALLEL)
2861 int len = XVECLEN (outgoing, 0);
2863 /* Check for a NULL entry, used to indicate that the parameter
2864 goes on the stack and in registers. */
2865 i = (XEXP (XVECEXP (outgoing, 0, 0), 0) ? 0 : 1);
2867 for ( ; i < len; ++i)
2869 rtx r = XVECEXP (outgoing, 0, i);
2870 if (GET_CODE (r) == REG)
2879 /* Determine which registers are live at the start of each
2880 basic block of the function whose first insn is F.
2881 NREGS is the number of registers used in F.
2882 We allocate the vector basic_block_live_at_start
2883 and the regsets that it points to, and fill them with the data.
2884 regset_size and regset_bytes are also set here. */
2887 life_analysis_1 (f, nregs, flags)
2892 char save_regs_ever_live[FIRST_PSEUDO_REGISTER];
2897 /* Allocate and zero out many data structures
2898 that will record the data from lifetime analysis. */
2900 allocate_reg_life_data ();
2901 allocate_bb_life_data ();
2903 reg_next_use = (rtx *) xcalloc (nregs, sizeof (rtx));
2905 /* Assume that the stack pointer is unchanging if alloca hasn't been used.
2906 This will be cleared by record_volatile_insns if it encounters an insn
2907 which modifies the stack pointer. */
2908 current_function_sp_is_unchanging = !current_function_calls_alloca;
2909 record_volatile_insns (f);
2911 /* Find the set of registers live on function exit. Do this before
2912 zeroing regs_ever_live, as we use that data post-reload. */
2913 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
2915 /* The post-reload life analysis have (on a global basis) the same
2916 registers live as was computed by reload itself. elimination
2917 Otherwise offsets and such may be incorrect.
2919 Reload will make some registers as live even though they do not
2920 appear in the rtl. */
2921 if (reload_completed)
2922 memcpy (save_regs_ever_live, regs_ever_live, sizeof (regs_ever_live));
2923 memset (regs_ever_live, 0, sizeof regs_ever_live);
2925 /* Compute register life at block boundaries. It'd be nice to
2926 begin with just the exit and noreturn blocks, but that set
2927 is not immediately handy. */
2930 blocks = sbitmap_alloc (n_basic_blocks);
2931 sbitmap_ones (blocks);
2932 calculate_global_regs_live (blocks, blocks, flags & PROP_SCAN_DEAD_CODE);
2933 sbitmap_free (blocks);
2936 /* The only pseudos that are live at the beginning of the function are
2937 those that were not set anywhere in the function. local-alloc doesn't
2938 know how to handle these correctly, so mark them as not local to any
2941 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
2942 FIRST_PSEUDO_REGISTER, i,
2943 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
2945 /* Now the life information is accurate. Make one more pass over each
2946 basic block to delete dead stores, create autoincrement addressing
2947 and record how many times each register is used, is set, or dies. */
2950 tmp = ALLOCA_REG_SET ();
2952 for (i = n_basic_blocks - 1; i >= 0; --i)
2954 basic_block bb = BASIC_BLOCK (i);
2956 COPY_REG_SET (tmp, bb->global_live_at_end);
2957 propagate_block (tmp, bb->head, bb->end, (regset) NULL, i, flags);
2963 /* We have a problem with any pseudoreg that lives across the setjmp.
2964 ANSI says that if a user variable does not change in value between
2965 the setjmp and the longjmp, then the longjmp preserves it. This
2966 includes longjmp from a place where the pseudo appears dead.
2967 (In principle, the value still exists if it is in scope.)
2968 If the pseudo goes in a hard reg, some other value may occupy
2969 that hard reg where this pseudo is dead, thus clobbering the pseudo.
2970 Conclusion: such a pseudo must not go in a hard reg. */
2971 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
2972 FIRST_PSEUDO_REGISTER, i,
2974 if (regno_reg_rtx[i] != 0)
2976 REG_LIVE_LENGTH (i) = -1;
2977 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
2981 /* Restore regs_ever_live that was provided by reload. */
2982 if (reload_completed)
2983 memcpy (regs_ever_live, save_regs_ever_live, sizeof (regs_ever_live));
2986 free (reg_next_use);
2987 reg_next_use = NULL;
2990 /* Propagate global life info around the graph of basic blocks. Begin
2991 considering blocks with their corresponding bit set in BLOCKS_IN.
2992 BLOCKS_OUT is set for every block that was changed. */
2995 calculate_global_regs_live (blocks_in, blocks_out, flags)
2996 sbitmap blocks_in, blocks_out;
2999 basic_block *queue, *qhead, *qtail, *qend;
3000 regset tmp, new_live_at_end;
3003 tmp = ALLOCA_REG_SET ();
3004 new_live_at_end = ALLOCA_REG_SET ();
3006 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3007 because the `head == tail' style test for an empty queue doesn't
3008 work with a full queue. */
3009 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3011 qhead = qend = queue + n_basic_blocks + 2;
3013 /* Clear out the garbage that might be hanging out in bb->aux. */
3014 for (i = n_basic_blocks - 1; i >= 0; --i)
3015 BASIC_BLOCK (i)->aux = NULL;
3017 /* Queue the blocks set in the initial mask. Do this in reverse block
3018 number order so that we are more likely for the first round to do
3019 useful work. We use AUX non-null to flag that the block is queued. */
3020 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3022 basic_block bb = BASIC_BLOCK (i);
3027 sbitmap_zero (blocks_out);
3029 while (qhead != qtail)
3031 int rescan, changed;
3040 /* Begin by propogating live_at_start from the successor blocks. */
3041 CLEAR_REG_SET (new_live_at_end);
3042 for (e = bb->succ; e ; e = e->succ_next)
3044 basic_block sb = e->dest;
3045 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3048 if (bb == ENTRY_BLOCK_PTR)
3050 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3054 /* On our first pass through this block, we'll go ahead and continue.
3055 Recognize first pass by local_set NULL. On subsequent passes, we
3056 get to skip out early if live_at_end wouldn't have changed. */
3058 if (bb->local_set == NULL)
3060 bb->local_set = OBSTACK_ALLOC_REG_SET (function_obstack);
3065 /* If any bits were removed from live_at_end, we'll have to
3066 rescan the block. This wouldn't be necessary if we had
3067 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3068 local_live is really dependant on live_at_end. */
3069 CLEAR_REG_SET (tmp);
3070 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3071 new_live_at_end, BITMAP_AND_COMPL);
3075 /* Find the set of changed bits. Take this opportunity
3076 to notice that this set is empty and early out. */
3077 CLEAR_REG_SET (tmp);
3078 changed = bitmap_operation (tmp, bb->global_live_at_end,
3079 new_live_at_end, BITMAP_XOR);
3083 /* If any of the changed bits overlap with local_set,
3084 we'll have to rescan the block. Detect overlap by
3085 the AND with ~local_set turning off bits. */
3086 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3091 /* Let our caller know that BB changed enough to require its
3092 death notes updated. */
3093 SET_BIT (blocks_out, bb->index);
3097 /* Add to live_at_start the set of all registers in
3098 new_live_at_end that aren't in the old live_at_end. */
3100 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3102 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3104 changed = bitmap_operation (bb->global_live_at_start,
3105 bb->global_live_at_start,
3112 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3114 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3115 into live_at_start. */
3116 propagate_block (new_live_at_end, bb->head, bb->end,
3117 bb->local_set, bb->index, flags);
3119 /* If live_at start didn't change, no need to go farther. */
3120 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3123 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3126 /* Queue all predecessors of BB so that we may re-examine
3127 their live_at_end. */
3128 for (e = bb->pred; e ; e = e->pred_next)
3130 basic_block pb = e->src;
3131 if (pb->aux == NULL)
3142 FREE_REG_SET (new_live_at_end);
3144 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3146 basic_block bb = BASIC_BLOCK (i);
3147 FREE_REG_SET (bb->local_set);
3153 /* Subroutines of life analysis. */
3155 /* Allocate the permanent data structures that represent the results
3156 of life analysis. Not static since used also for stupid life analysis. */
3159 allocate_bb_life_data ()
3163 for (i = 0; i < n_basic_blocks; i++)
3165 basic_block bb = BASIC_BLOCK (i);
3167 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
3168 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
3171 ENTRY_BLOCK_PTR->global_live_at_end
3172 = OBSTACK_ALLOC_REG_SET (function_obstack);
3173 EXIT_BLOCK_PTR->global_live_at_start
3174 = OBSTACK_ALLOC_REG_SET (function_obstack);
3176 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (function_obstack);
3180 allocate_reg_life_data ()
3184 /* Recalculate the register space, in case it has grown. Old style
3185 vector oriented regsets would set regset_{size,bytes} here also. */
3186 allocate_reg_info (max_regno, FALSE, FALSE);
3188 /* Reset all the data we'll collect in propagate_block and its
3190 for (i = 0; i < max_regno; i++)
3194 REG_N_DEATHS (i) = 0;
3195 REG_N_CALLS_CROSSED (i) = 0;
3196 REG_LIVE_LENGTH (i) = 0;
3197 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3201 /* Compute the registers live at the beginning of a basic block
3202 from those live at the end.
3204 When called, OLD contains those live at the end.
3205 On return, it contains those live at the beginning.
3206 FIRST and LAST are the first and last insns of the basic block.
3208 FINAL is nonzero if we are doing the final pass which is not
3209 for computing the life info (since that has already been done)
3210 but for acting on it. On this pass, we delete dead stores,
3211 set up the logical links and dead-variables lists of instructions,
3212 and merge instructions for autoincrement and autodecrement addresses.
3214 SIGNIFICANT is nonzero only the first time for each basic block.
3215 If it is nonzero, it points to a regset in which we store
3216 a 1 for each register that is set within the block.
3218 BNUM is the number of the basic block. */
3221 propagate_block (old, first, last, significant, bnum, flags)
3222 register regset old;
3234 /* Find the loop depth for this block. Ignore loop level changes in the
3235 middle of the basic block -- for register allocation purposes, the
3236 important uses will be in the blocks wholely contained within the loop
3237 not in the loop pre-header or post-trailer. */
3238 loop_depth = BASIC_BLOCK (bnum)->loop_depth;
3240 dead = ALLOCA_REG_SET ();
3241 live = ALLOCA_REG_SET ();
3245 if (flags & PROP_REG_INFO)
3249 /* Process the regs live at the end of the block.
3250 Mark them as not local to any one basic block. */
3251 EXECUTE_IF_SET_IN_REG_SET (old, 0, i,
3253 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
3257 /* Scan the block an insn at a time from end to beginning. */
3259 for (insn = last; ; insn = prev)
3261 prev = PREV_INSN (insn);
3263 if (GET_CODE (insn) == NOTE)
3265 /* If this is a call to `setjmp' et al,
3266 warn if any non-volatile datum is live. */
3268 if ((flags & PROP_REG_INFO)
3269 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
3270 IOR_REG_SET (regs_live_at_setjmp, old);
3273 /* Update the life-status of regs for this insn.
3274 First DEAD gets which regs are set in this insn
3275 then LIVE gets which regs are used in this insn.
3276 Then the regs live before the insn
3277 are those live after, with DEAD regs turned off,
3278 and then LIVE regs turned on. */
3280 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
3283 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3284 int insn_is_dead = 0;
3285 int libcall_is_dead = 0;
3287 if (flags & PROP_SCAN_DEAD_CODE)
3289 insn_is_dead = (insn_dead_p (PATTERN (insn), old, 0, REG_NOTES (insn))
3290 /* Don't delete something that refers to volatile storage! */
3291 && ! INSN_VOLATILE (insn));
3292 libcall_is_dead = (insn_is_dead && note != 0
3293 && libcall_dead_p (PATTERN (insn), old, note, insn));
3296 /* We almost certainly don't want to delete prologue or epilogue
3297 instructions. Warn about probable compiler losage. */
3300 && (HAVE_epilogue || HAVE_prologue)
3301 && prologue_epilogue_contains (insn))
3303 if (flags & PROP_KILL_DEAD_CODE)
3305 warning ("ICE: would have deleted prologue/epilogue insn");
3306 if (!inhibit_warnings)
3309 libcall_is_dead = insn_is_dead = 0;
3312 /* If an instruction consists of just dead store(s) on final pass,
3313 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
3314 We could really delete it with delete_insn, but that
3315 can cause trouble for first or last insn in a basic block. */
3316 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3319 /* If the insn referred to a label, note that the label is
3321 for (inote = REG_NOTES (insn); inote; inote = XEXP (inote, 1))
3323 if (REG_NOTE_KIND (inote) == REG_LABEL)
3325 rtx label = XEXP (inote, 0);
3327 LABEL_NUSES (label)--;
3329 /* If this label was attached to an ADDR_VEC, it's
3330 safe to delete the ADDR_VEC. In fact, it's pretty much
3331 mandatory to delete it, because the ADDR_VEC may
3332 be referencing labels that no longer exist. */
3333 if (LABEL_NUSES (label) == 0
3334 && (next = next_nonnote_insn (label)) != NULL
3335 && GET_CODE (next) == JUMP_INSN
3336 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3337 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3339 rtx pat = PATTERN (next);
3340 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3341 int len = XVECLEN (pat, diff_vec_p);
3343 for (i = 0; i < len; i++)
3344 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3345 PUT_CODE (next, NOTE);
3346 NOTE_LINE_NUMBER (next) = NOTE_INSN_DELETED;
3347 NOTE_SOURCE_FILE (next) = 0;
3352 PUT_CODE (insn, NOTE);
3353 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3354 NOTE_SOURCE_FILE (insn) = 0;
3356 /* CC0 is now known to be dead. Either this insn used it,
3357 in which case it doesn't anymore, or clobbered it,
3358 so the next insn can't use it. */
3361 /* If this insn is copying the return value from a library call,
3362 delete the entire library call. */
3363 if (libcall_is_dead)
3365 rtx first = XEXP (note, 0);
3367 while (INSN_DELETED_P (first))
3368 first = NEXT_INSN (first);
3373 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
3374 NOTE_SOURCE_FILE (p) = 0;
3380 CLEAR_REG_SET (dead);
3381 CLEAR_REG_SET (live);
3383 /* See if this is an increment or decrement that can be
3384 merged into a following memory address. */
3387 register rtx x = single_set (insn);
3389 /* Does this instruction increment or decrement a register? */
3390 if (!reload_completed
3391 && (flags & PROP_AUTOINC)
3393 && GET_CODE (SET_DEST (x)) == REG
3394 && (GET_CODE (SET_SRC (x)) == PLUS
3395 || GET_CODE (SET_SRC (x)) == MINUS)
3396 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3397 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3398 /* Ok, look for a following memory ref we can combine with.
3399 If one is found, change the memory ref to a PRE_INC
3400 or PRE_DEC, cancel this insn, and return 1.
3401 Return 0 if nothing has been done. */
3402 && try_pre_increment_1 (insn))
3405 #endif /* AUTO_INC_DEC */
3407 /* If this is not the final pass, and this insn is copying the
3408 value of a library call and it's dead, don't scan the
3409 insns that perform the library call, so that the call's
3410 arguments are not marked live. */
3411 if (libcall_is_dead)
3413 /* Mark the dest reg as `significant'. */
3414 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX,
3415 significant, flags);
3417 insn = XEXP (note, 0);
3418 prev = PREV_INSN (insn);
3420 else if (GET_CODE (PATTERN (insn)) == SET
3421 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3422 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3423 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3424 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3425 /* We have an insn to pop a constant amount off the stack.
3426 (Such insns use PLUS regardless of the direction of the stack,
3427 and any insn to adjust the stack by a constant is always a pop.)
3428 These insns, if not dead stores, have no effect on life. */
3432 /* Any regs live at the time of a call instruction
3433 must not go in a register clobbered by calls.
3434 Find all regs now live and record this for them. */
3436 if (GET_CODE (insn) == CALL_INSN
3437 && (flags & PROP_REG_INFO))
3438 EXECUTE_IF_SET_IN_REG_SET (old, 0, i,
3440 REG_N_CALLS_CROSSED (i)++;
3443 /* LIVE gets the regs used in INSN;
3444 DEAD gets those set by it. Dead insns don't make anything
3447 mark_set_regs (old, dead, PATTERN (insn),
3448 insn, significant, flags);
3450 /* If an insn doesn't use CC0, it becomes dead since we
3451 assume that every insn clobbers it. So show it dead here;
3452 mark_used_regs will set it live if it is referenced. */
3456 mark_used_regs (old, live, PATTERN (insn), flags, insn);
3458 /* Sometimes we may have inserted something before INSN (such as
3459 a move) when we make an auto-inc. So ensure we will scan
3462 prev = PREV_INSN (insn);
3465 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3471 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3473 note = XEXP (note, 1))
3474 if (GET_CODE (XEXP (note, 0)) == USE)
3475 mark_used_regs (old, live, XEXP (XEXP (note, 0), 0),
3478 /* Each call clobbers all call-clobbered regs that are not
3479 global or fixed. Note that the function-value reg is a
3480 call-clobbered reg, and mark_set_regs has already had
3481 a chance to handle it. */
3483 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3484 if (call_used_regs[i] && ! global_regs[i]
3487 SET_REGNO_REG_SET (dead, i);
3489 SET_REGNO_REG_SET (significant, i);
3492 /* The stack ptr is used (honorarily) by a CALL insn. */
3493 SET_REGNO_REG_SET (live, STACK_POINTER_REGNUM);
3495 /* Calls may also reference any of the global registers,
3496 so they are made live. */
3497 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3499 mark_used_regs (old, live,
3500 gen_rtx_REG (reg_raw_mode[i], i),
3503 /* Calls also clobber memory. */
3504 free_EXPR_LIST_list (&mem_set_list);
3507 /* Update OLD for the registers used or set. */
3508 AND_COMPL_REG_SET (old, dead);
3509 IOR_REG_SET (old, live);
3513 /* On final pass, update counts of how many insns each reg is live
3515 if (flags & PROP_REG_INFO)
3516 EXECUTE_IF_SET_IN_REG_SET (old, 0, i,
3517 { REG_LIVE_LENGTH (i)++; });
3524 FREE_REG_SET (dead);
3525 FREE_REG_SET (live);
3526 free_EXPR_LIST_list (&mem_set_list);
3529 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
3530 (SET expressions whose destinations are registers dead after the insn).
3531 NEEDED is the regset that says which regs are alive after the insn.
3533 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
3535 If X is the entire body of an insn, NOTES contains the reg notes
3536 pertaining to the insn. */
3539 insn_dead_p (x, needed, call_ok, notes)
3543 rtx notes ATTRIBUTE_UNUSED;
3545 enum rtx_code code = GET_CODE (x);
3548 /* If flow is invoked after reload, we must take existing AUTO_INC
3549 expresions into account. */
3550 if (reload_completed)
3552 for ( ; notes; notes = XEXP (notes, 1))
3554 if (REG_NOTE_KIND (notes) == REG_INC)
3556 int regno = REGNO (XEXP (notes, 0));
3558 /* Don't delete insns to set global regs. */
3559 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
3560 || REGNO_REG_SET_P (needed, regno))
3567 /* If setting something that's a reg or part of one,
3568 see if that register's altered value will be live. */
3572 rtx r = SET_DEST (x);
3574 /* A SET that is a subroutine call cannot be dead. */
3575 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
3579 if (GET_CODE (r) == CC0)
3583 if (GET_CODE (r) == MEM && ! MEM_VOLATILE_P (r))
3586 /* Walk the set of memory locations we are currently tracking
3587 and see if one is an identical match to this memory location.
3588 If so, this memory write is dead (remember, we're walking
3589 backwards from the end of the block to the start. */
3590 temp = mem_set_list;
3593 if (rtx_equal_p (XEXP (temp, 0), r))
3595 temp = XEXP (temp, 1);
3599 while (GET_CODE (r) == SUBREG || GET_CODE (r) == STRICT_LOW_PART
3600 || GET_CODE (r) == ZERO_EXTRACT)
3603 if (GET_CODE (r) == REG)
3605 int regno = REGNO (r);
3607 /* Don't delete insns to set global regs. */
3608 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
3609 /* Make sure insns to set frame pointer aren't deleted. */
3610 || (regno == FRAME_POINTER_REGNUM
3611 && (! reload_completed || frame_pointer_needed))
3612 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3613 || (regno == HARD_FRAME_POINTER_REGNUM
3614 && (! reload_completed || frame_pointer_needed))
3616 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3617 /* Make sure insns to set arg pointer are never deleted
3618 (if the arg pointer isn't fixed, there will be a USE for
3619 it, so we can treat it normally). */
3620 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3622 || REGNO_REG_SET_P (needed, regno))
3625 /* If this is a hard register, verify that subsequent words are
3627 if (regno < FIRST_PSEUDO_REGISTER)
3629 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
3632 if (REGNO_REG_SET_P (needed, regno+n))
3640 /* If performing several activities,
3641 insn is dead if each activity is individually dead.
3642 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
3643 that's inside a PARALLEL doesn't make the insn worth keeping. */
3644 else if (code == PARALLEL)
3646 int i = XVECLEN (x, 0);
3648 for (i--; i >= 0; i--)
3649 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
3650 && GET_CODE (XVECEXP (x, 0, i)) != USE
3651 && ! insn_dead_p (XVECEXP (x, 0, i), needed, call_ok, NULL_RTX))
3657 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
3658 is not necessarily true for hard registers. */
3659 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
3660 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
3661 && ! REGNO_REG_SET_P (needed, REGNO (XEXP (x, 0))))
3664 /* We do not check other CLOBBER or USE here. An insn consisting of just
3665 a CLOBBER or just a USE should not be deleted. */
3669 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
3670 return 1 if the entire library call is dead.
3671 This is true if X copies a register (hard or pseudo)
3672 and if the hard return reg of the call insn is dead.
3673 (The caller should have tested the destination of X already for death.)
3675 If this insn doesn't just copy a register, then we don't
3676 have an ordinary libcall. In that case, cse could not have
3677 managed to substitute the source for the dest later on,
3678 so we can assume the libcall is dead.
3680 NEEDED is the bit vector of pseudoregs live before this insn.
3681 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
3684 libcall_dead_p (x, needed, note, insn)
3690 register RTX_CODE code = GET_CODE (x);
3694 register rtx r = SET_SRC (x);
3695 if (GET_CODE (r) == REG)
3697 rtx call = XEXP (note, 0);
3701 /* Find the call insn. */
3702 while (call != insn && GET_CODE (call) != CALL_INSN)
3703 call = NEXT_INSN (call);
3705 /* If there is none, do nothing special,
3706 since ordinary death handling can understand these insns. */
3710 /* See if the hard reg holding the value is dead.
3711 If this is a PARALLEL, find the call within it. */
3712 call_pat = PATTERN (call);
3713 if (GET_CODE (call_pat) == PARALLEL)
3715 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
3716 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
3717 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
3720 /* This may be a library call that is returning a value
3721 via invisible pointer. Do nothing special, since
3722 ordinary death handling can understand these insns. */
3726 call_pat = XVECEXP (call_pat, 0, i);
3729 return insn_dead_p (call_pat, needed, 1, REG_NOTES (call));
3735 /* Return 1 if register REGNO was used before it was set, i.e. if it is
3736 live at function entry. Don't count global register variables, variables
3737 in registers that can be used for function arg passing, or variables in
3738 fixed hard registers. */
3741 regno_uninitialized (regno)
3744 if (n_basic_blocks == 0
3745 || (regno < FIRST_PSEUDO_REGISTER
3746 && (global_regs[regno]
3747 || fixed_regs[regno]
3748 || FUNCTION_ARG_REGNO_P (regno))))
3751 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
3754 /* 1 if register REGNO was alive at a place where `setjmp' was called
3755 and was set more than once or is an argument.
3756 Such regs may be clobbered by `longjmp'. */
3759 regno_clobbered_at_setjmp (regno)
3762 if (n_basic_blocks == 0)
3765 return ((REG_N_SETS (regno) > 1
3766 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
3767 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
3770 /* INSN references memory, possibly using autoincrement addressing modes.
3771 Find any entries on the mem_set_list that need to be invalidated due
3772 to an address change. */
3774 invalidate_mems_from_autoinc (insn)
3777 rtx note = REG_NOTES (insn);
3778 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
3780 if (REG_NOTE_KIND (note) == REG_INC)
3782 rtx temp = mem_set_list;
3783 rtx prev = NULL_RTX;
3788 next = XEXP (temp, 1);
3789 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
3791 /* Splice temp out of list. */
3793 XEXP (prev, 1) = next;
3795 mem_set_list = next;
3796 free_EXPR_LIST_node (temp);
3806 /* Process the registers that are set within X. Their bits are set to
3807 1 in the regset DEAD, because they are dead prior to this insn.
3809 If INSN is nonzero, it is the insn being processed.
3811 FLAGS is the set of operations to perform. */
3814 mark_set_regs (needed, dead, x, insn, significant, flags)
3822 register RTX_CODE code = GET_CODE (x);
3824 if (code == SET || code == CLOBBER)
3825 mark_set_1 (needed, dead, x, insn, significant, flags);
3826 else if (code == PARALLEL)
3829 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
3831 code = GET_CODE (XVECEXP (x, 0, i));
3832 if (code == SET || code == CLOBBER)
3833 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn,
3834 significant, flags);
3839 /* Process a single SET rtx, X. */
3842 mark_set_1 (needed, dead, x, insn, significant, flags)
3850 register int regno = -1;
3851 register rtx reg = SET_DEST (x);
3853 /* Some targets place small structures in registers for
3854 return values of functions. We have to detect this
3855 case specially here to get correct flow information. */
3856 if (GET_CODE (reg) == PARALLEL
3857 && GET_MODE (reg) == BLKmode)
3861 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
3862 mark_set_1 (needed, dead, XVECEXP (reg, 0, i), insn,
3863 significant, flags);
3867 /* Modifying just one hardware register of a multi-reg value
3868 or just a byte field of a register
3869 does not mean the value from before this insn is now dead.
3870 But it does mean liveness of that register at the end of the block
3873 Within mark_set_1, however, we treat it as if the register is
3874 indeed modified. mark_used_regs will, however, also treat this
3875 register as being used. Thus, we treat these insns as setting a
3876 new value for the register as a function of its old value. This
3877 cases LOG_LINKS to be made appropriately and this will help combine. */
3879 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
3880 || GET_CODE (reg) == SIGN_EXTRACT
3881 || GET_CODE (reg) == STRICT_LOW_PART)
3882 reg = XEXP (reg, 0);
3884 /* If this set is a MEM, then it kills any aliased writes.
3885 If this set is a REG, then it kills any MEMs which use the reg. */
3886 if (flags & PROP_SCAN_DEAD_CODE)
3888 if (GET_CODE (reg) == MEM
3889 || GET_CODE (reg) == REG)
3891 rtx temp = mem_set_list;
3892 rtx prev = NULL_RTX;
3897 next = XEXP (temp, 1);
3898 if ((GET_CODE (reg) == MEM
3899 && output_dependence (XEXP (temp, 0), reg))
3900 || (GET_CODE (reg) == REG
3901 && reg_overlap_mentioned_p (reg, XEXP (temp, 0))))
3903 /* Splice this entry out of the list. */
3905 XEXP (prev, 1) = next;
3907 mem_set_list = next;
3908 free_EXPR_LIST_node (temp);
3916 /* If the memory reference had embedded side effects (autoincrement
3917 address modes. Then we may need to kill some entries on the
3919 if (insn && GET_CODE (reg) == MEM)
3920 invalidate_mems_from_autoinc (insn);
3922 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
3923 /* We do not know the size of a BLKmode store, so we do not track
3924 them for redundant store elimination. */
3925 && GET_MODE (reg) != BLKmode
3926 /* There are no REG_INC notes for SP, so we can't assume we'll see
3927 everything that invalidates it. To be safe, don't eliminate any
3928 stores though SP; none of them should be redundant anyway. */
3929 && ! reg_mentioned_p (stack_pointer_rtx, reg))
3930 mem_set_list = alloc_EXPR_LIST (0, reg, mem_set_list);
3933 if (GET_CODE (reg) == REG
3934 && (regno = REGNO (reg),
3935 ! (regno == FRAME_POINTER_REGNUM
3936 && (! reload_completed || frame_pointer_needed)))
3937 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3938 && ! (regno == HARD_FRAME_POINTER_REGNUM
3939 && (! reload_completed || frame_pointer_needed))
3941 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3942 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3944 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
3945 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
3947 int some_needed = REGNO_REG_SET_P (needed, regno);
3948 int some_not_needed = ! some_needed;
3950 /* Mark it as a significant register for this basic block. */
3952 SET_REGNO_REG_SET (significant, regno);
3954 /* Mark it as dead before this insn. */
3955 SET_REGNO_REG_SET (dead, regno);
3957 /* A hard reg in a wide mode may really be multiple registers.
3958 If so, mark all of them just like the first. */
3959 if (regno < FIRST_PSEUDO_REGISTER)
3963 /* Nothing below is needed for the stack pointer; get out asap.
3964 Eg, log links aren't needed, since combine won't use them. */
3965 if (regno == STACK_POINTER_REGNUM)
3968 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3971 int regno_n = regno + n;
3972 int needed_regno = REGNO_REG_SET_P (needed, regno_n);
3974 SET_REGNO_REG_SET (significant, regno_n);
3976 SET_REGNO_REG_SET (dead, regno_n);
3977 some_needed |= needed_regno;
3978 some_not_needed |= ! needed_regno;
3982 /* Additional data to record if this is the final pass. */
3983 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
3984 | PROP_DEATH_NOTES | PROP_AUTOINC))
3987 register int blocknum = BLOCK_NUM (insn);
3990 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3991 y = reg_next_use[regno];
3993 /* If this is a hard reg, record this function uses the reg. */
3995 if (regno < FIRST_PSEUDO_REGISTER)
3998 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
4000 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4001 for (i = regno; i < endregno; i++)
4003 /* The next use is no longer "next", since a store
4005 reg_next_use[i] = 0;
4008 if (flags & PROP_REG_INFO)
4009 for (i = regno; i < endregno; i++)
4011 regs_ever_live[i] = 1;
4017 /* The next use is no longer "next", since a store
4019 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4020 reg_next_use[regno] = 0;
4022 /* Keep track of which basic blocks each reg appears in. */
4024 if (flags & PROP_REG_INFO)
4026 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
4027 REG_BASIC_BLOCK (regno) = blocknum;
4028 else if (REG_BASIC_BLOCK (regno) != blocknum)
4029 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
4031 /* Count (weighted) references, stores, etc. This counts a
4032 register twice if it is modified, but that is correct. */
4033 REG_N_SETS (regno)++;
4034 REG_N_REFS (regno) += loop_depth + 1;
4036 /* The insns where a reg is live are normally counted
4037 elsewhere, but we want the count to include the insn
4038 where the reg is set, and the normal counting mechanism
4039 would not count it. */
4040 REG_LIVE_LENGTH (regno)++;
4044 if (! some_not_needed)
4046 if (flags & PROP_LOG_LINKS)
4048 /* Make a logical link from the next following insn
4049 that uses this register, back to this insn.
4050 The following insns have already been processed.
4052 We don't build a LOG_LINK for hard registers containing
4053 in ASM_OPERANDs. If these registers get replaced,
4054 we might wind up changing the semantics of the insn,
4055 even if reload can make what appear to be valid
4056 assignments later. */
4057 if (y && (BLOCK_NUM (y) == blocknum)
4058 && (regno >= FIRST_PSEUDO_REGISTER
4059 || asm_noperands (PATTERN (y)) < 0))
4060 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4063 else if (! some_needed)
4065 if (flags & PROP_REG_INFO)
4066 REG_N_DEATHS (REGNO (reg))++;
4068 if (flags & PROP_DEATH_NOTES)
4070 /* Note that dead stores have already been deleted
4071 when possible. If we get here, we have found a
4072 dead store that cannot be eliminated (because the
4073 same insn does something useful). Indicate this
4074 by marking the reg being set as dying here. */
4076 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4081 if (flags & PROP_DEATH_NOTES)
4083 /* This is a case where we have a multi-word hard register
4084 and some, but not all, of the words of the register are
4085 needed in subsequent insns. Write REG_UNUSED notes
4086 for those parts that were not needed. This case should
4091 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
4093 if (!REGNO_REG_SET_P (needed, regno + i))
4097 gen_rtx_REG (reg_raw_mode[regno + i], regno + i),
4103 else if (GET_CODE (reg) == REG)
4105 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4106 reg_next_use[regno] = 0;
4109 /* If this is the last pass and this is a SCRATCH, show it will be dying
4110 here and count it. */
4111 else if (GET_CODE (reg) == SCRATCH)
4113 if (flags & PROP_DEATH_NOTES)
4115 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4121 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
4125 find_auto_inc (needed, x, insn)
4130 rtx addr = XEXP (x, 0);
4131 HOST_WIDE_INT offset = 0;
4134 /* Here we detect use of an index register which might be good for
4135 postincrement, postdecrement, preincrement, or predecrement. */
4137 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
4138 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
4140 if (GET_CODE (addr) == REG)
4143 register int size = GET_MODE_SIZE (GET_MODE (x));
4146 int regno = REGNO (addr);
4148 /* Is the next use an increment that might make auto-increment? */
4149 if ((incr = reg_next_use[regno]) != 0
4150 && (set = single_set (incr)) != 0
4151 && GET_CODE (set) == SET
4152 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
4153 /* Can't add side effects to jumps; if reg is spilled and
4154 reloaded, there's no way to store back the altered value. */
4155 && GET_CODE (insn) != JUMP_INSN
4156 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
4157 && XEXP (y, 0) == addr
4158 && GET_CODE (XEXP (y, 1)) == CONST_INT
4159 && ((HAVE_POST_INCREMENT
4160 && (INTVAL (XEXP (y, 1)) == size && offset == 0))
4161 || (HAVE_POST_DECREMENT
4162 && (INTVAL (XEXP (y, 1)) == - size && offset == 0))
4163 || (HAVE_PRE_INCREMENT
4164 && (INTVAL (XEXP (y, 1)) == size && offset == size))
4165 || (HAVE_PRE_DECREMENT
4166 && (INTVAL (XEXP (y, 1)) == - size && offset == - size)))
4167 /* Make sure this reg appears only once in this insn. */
4168 && (use = find_use_as_address (PATTERN (insn), addr, offset),
4169 use != 0 && use != (rtx) 1))
4171 rtx q = SET_DEST (set);
4172 enum rtx_code inc_code = (INTVAL (XEXP (y, 1)) == size
4173 ? (offset ? PRE_INC : POST_INC)
4174 : (offset ? PRE_DEC : POST_DEC));
4176 if (dead_or_set_p (incr, addr))
4178 /* This is the simple case. Try to make the auto-inc. If
4179 we can't, we are done. Otherwise, we will do any
4180 needed updates below. */
4181 if (! validate_change (insn, &XEXP (x, 0),
4182 gen_rtx_fmt_e (inc_code, Pmode, addr),
4186 else if (GET_CODE (q) == REG
4187 /* PREV_INSN used here to check the semi-open interval
4189 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
4190 /* We must also check for sets of q as q may be
4191 a call clobbered hard register and there may
4192 be a call between PREV_INSN (insn) and incr. */
4193 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
4195 /* We have *p followed sometime later by q = p+size.
4196 Both p and q must be live afterward,
4197 and q is not used between INSN and its assignment.
4198 Change it to q = p, ...*q..., q = q+size.
4199 Then fall into the usual case. */
4204 emit_move_insn (q, addr);
4205 insns = get_insns ();
4208 bb = BLOCK_FOR_INSN (insn);
4209 for (temp = insns; temp; temp = NEXT_INSN (temp))
4210 set_block_for_insn (temp, bb);
4212 /* If we can't make the auto-inc, or can't make the
4213 replacement into Y, exit. There's no point in making
4214 the change below if we can't do the auto-inc and doing
4215 so is not correct in the pre-inc case. */
4217 validate_change (insn, &XEXP (x, 0),
4218 gen_rtx_fmt_e (inc_code, Pmode, q),
4220 validate_change (incr, &XEXP (y, 0), q, 1);
4221 if (! apply_change_group ())
4224 /* We now know we'll be doing this change, so emit the
4225 new insn(s) and do the updates. */
4226 emit_insns_before (insns, insn);
4228 if (BLOCK_FOR_INSN (insn)->head == insn)
4229 BLOCK_FOR_INSN (insn)->head = insns;
4231 /* INCR will become a NOTE and INSN won't contain a
4232 use of ADDR. If a use of ADDR was just placed in
4233 the insn before INSN, make that the next use.
4234 Otherwise, invalidate it. */
4235 if (GET_CODE (PREV_INSN (insn)) == INSN
4236 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
4237 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
4238 reg_next_use[regno] = PREV_INSN (insn);
4240 reg_next_use[regno] = 0;
4245 /* REGNO is now used in INCR which is below INSN, but
4246 it previously wasn't live here. If we don't mark
4247 it as needed, we'll put a REG_DEAD note for it
4248 on this insn, which is incorrect. */
4249 SET_REGNO_REG_SET (needed, regno);
4251 /* If there are any calls between INSN and INCR, show
4252 that REGNO now crosses them. */
4253 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
4254 if (GET_CODE (temp) == CALL_INSN)
4255 REG_N_CALLS_CROSSED (regno)++;
4260 /* If we haven't returned, it means we were able to make the
4261 auto-inc, so update the status. First, record that this insn
4262 has an implicit side effect. */
4265 = alloc_EXPR_LIST (REG_INC, addr, REG_NOTES (insn));
4267 /* Modify the old increment-insn to simply copy
4268 the already-incremented value of our register. */
4269 if (! validate_change (incr, &SET_SRC (set), addr, 0))
4272 /* If that makes it a no-op (copying the register into itself) delete
4273 it so it won't appear to be a "use" and a "set" of this
4275 if (SET_DEST (set) == addr)
4277 PUT_CODE (incr, NOTE);
4278 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
4279 NOTE_SOURCE_FILE (incr) = 0;
4282 if (regno >= FIRST_PSEUDO_REGISTER)
4284 /* Count an extra reference to the reg. When a reg is
4285 incremented, spilling it is worse, so we want to make
4286 that less likely. */
4287 REG_N_REFS (regno) += loop_depth + 1;
4289 /* Count the increment as a setting of the register,
4290 even though it isn't a SET in rtl. */
4291 REG_N_SETS (regno)++;
4296 #endif /* AUTO_INC_DEC */
4298 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
4299 This is done assuming the registers needed from X
4300 are those that have 1-bits in NEEDED.
4302 FLAGS is the set of enabled operations.
4304 INSN is the containing instruction. If INSN is dead, this function is not
4308 mark_used_regs (needed, live, x, flags, insn)
4315 register RTX_CODE code;
4320 code = GET_CODE (x);
4340 /* If we are clobbering a MEM, mark any registers inside the address
4342 if (GET_CODE (XEXP (x, 0)) == MEM)
4343 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), flags, insn);
4347 /* Don't bother watching stores to mems if this is not the
4348 final pass. We'll not be deleting dead stores this round. */
4349 if (flags & PROP_SCAN_DEAD_CODE)
4351 /* Invalidate the data for the last MEM stored, but only if MEM is
4352 something that can be stored into. */
4353 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
4354 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
4355 ; /* needn't clear the memory set list */
4358 rtx temp = mem_set_list;
4359 rtx prev = NULL_RTX;
4364 next = XEXP (temp, 1);
4365 if (anti_dependence (XEXP (temp, 0), x))
4367 /* Splice temp out of the list. */
4369 XEXP (prev, 1) = next;
4371 mem_set_list = next;
4372 free_EXPR_LIST_node (temp);
4380 /* If the memory reference had embedded side effects (autoincrement
4381 address modes. Then we may need to kill some entries on the
4384 invalidate_mems_from_autoinc (insn);
4388 if (flags & PROP_AUTOINC)
4389 find_auto_inc (needed, x, insn);
4394 if (GET_CODE (SUBREG_REG (x)) == REG
4395 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
4396 && (GET_MODE_SIZE (GET_MODE (x))
4397 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
4398 REG_CHANGES_SIZE (REGNO (SUBREG_REG (x))) = 1;
4400 /* While we're here, optimize this case. */
4403 /* In case the SUBREG is not of a register, don't optimize */
4404 if (GET_CODE (x) != REG)
4406 mark_used_regs (needed, live, x, flags, insn);
4410 /* ... fall through ... */
4413 /* See a register other than being set
4414 => mark it as needed. */
4418 int some_needed = REGNO_REG_SET_P (needed, regno);
4419 int some_not_needed = ! some_needed;
4421 SET_REGNO_REG_SET (live, regno);
4423 /* A hard reg in a wide mode may really be multiple registers.
4424 If so, mark all of them just like the first. */
4425 if (regno < FIRST_PSEUDO_REGISTER)
4429 /* For stack ptr or fixed arg pointer,
4430 nothing below can be necessary, so waste no more time. */
4431 if (regno == STACK_POINTER_REGNUM
4432 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4433 || (regno == HARD_FRAME_POINTER_REGNUM
4434 && (! reload_completed || frame_pointer_needed))
4436 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4437 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4439 || (regno == FRAME_POINTER_REGNUM
4440 && (! reload_completed || frame_pointer_needed)))
4442 /* If this is a register we are going to try to eliminate,
4443 don't mark it live here. If we are successful in
4444 eliminating it, it need not be live unless it is used for
4445 pseudos, in which case it will have been set live when
4446 it was allocated to the pseudos. If the register will not
4447 be eliminated, reload will set it live at that point. */
4449 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
4450 regs_ever_live[regno] = 1;
4453 /* No death notes for global register variables;
4454 their values are live after this function exits. */
4455 if (global_regs[regno])
4457 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4458 reg_next_use[regno] = insn;
4462 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
4465 int regno_n = regno + n;
4466 int needed_regno = REGNO_REG_SET_P (needed, regno_n);
4468 SET_REGNO_REG_SET (live, regno_n);
4469 some_needed |= needed_regno;
4470 some_not_needed |= ! needed_regno;
4474 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4476 /* Record where each reg is used, so when the reg
4477 is set we know the next insn that uses it. */
4479 reg_next_use[regno] = insn;
4481 if (flags & PROP_REG_INFO)
4483 if (regno < FIRST_PSEUDO_REGISTER)
4485 /* If a hard reg is being used,
4486 record that this function does use it. */
4488 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
4492 regs_ever_live[regno + --i] = 1;
4497 /* Keep track of which basic block each reg appears in. */
4499 register int blocknum = BLOCK_NUM (insn);
4501 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
4502 REG_BASIC_BLOCK (regno) = blocknum;
4503 else if (REG_BASIC_BLOCK (regno) != blocknum)
4504 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
4506 /* Count (weighted) number of uses of each reg. */
4508 REG_N_REFS (regno) += loop_depth + 1;
4512 /* Record and count the insns in which a reg dies.
4513 If it is used in this insn and was dead below the insn
4514 then it dies in this insn. If it was set in this insn,
4515 we do not make a REG_DEAD note; likewise if we already
4516 made such a note. */
4518 if (flags & PROP_DEATH_NOTES)
4521 && ! dead_or_set_p (insn, x)
4523 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
4527 /* Check for the case where the register dying partially
4528 overlaps the register set by this insn. */
4529 if (regno < FIRST_PSEUDO_REGISTER
4530 && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
4532 int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
4534 some_needed |= dead_or_set_regno_p (insn, regno + n);
4537 /* If none of the words in X is needed, make a REG_DEAD
4538 note. Otherwise, we must make partial REG_DEAD notes. */
4542 = alloc_EXPR_LIST (REG_DEAD, x, REG_NOTES (insn));
4543 REG_N_DEATHS (regno)++;
4549 /* Don't make a REG_DEAD note for a part of a register
4550 that is set in the insn. */
4552 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
4554 if (!REGNO_REG_SET_P (needed, regno + i)
4555 && ! dead_or_set_regno_p (insn, regno + i))
4558 (REG_DEAD, gen_rtx_REG (reg_raw_mode[regno + i],
4569 register rtx testreg = SET_DEST (x);
4572 /* If storing into MEM, don't show it as being used. But do
4573 show the address as being used. */
4574 if (GET_CODE (testreg) == MEM)
4577 if (flags & PROP_AUTOINC)
4578 find_auto_inc (needed, testreg, insn);
4580 mark_used_regs (needed, live, XEXP (testreg, 0), flags, insn);
4581 mark_used_regs (needed, live, SET_SRC (x), flags, insn);
4585 /* Storing in STRICT_LOW_PART is like storing in a reg
4586 in that this SET might be dead, so ignore it in TESTREG.
4587 but in some other ways it is like using the reg.
4589 Storing in a SUBREG or a bit field is like storing the entire
4590 register in that if the register's value is not used
4591 then this SET is not needed. */
4592 while (GET_CODE (testreg) == STRICT_LOW_PART
4593 || GET_CODE (testreg) == ZERO_EXTRACT
4594 || GET_CODE (testreg) == SIGN_EXTRACT
4595 || GET_CODE (testreg) == SUBREG)
4597 if (GET_CODE (testreg) == SUBREG
4598 && GET_CODE (SUBREG_REG (testreg)) == REG
4599 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
4600 && (GET_MODE_SIZE (GET_MODE (testreg))
4601 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (testreg)))))
4602 REG_CHANGES_SIZE (REGNO (SUBREG_REG (testreg))) = 1;
4604 /* Modifying a single register in an alternate mode
4605 does not use any of the old value. But these other
4606 ways of storing in a register do use the old value. */
4607 if (GET_CODE (testreg) == SUBREG
4608 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
4613 testreg = XEXP (testreg, 0);
4616 /* If this is a store into a register,
4617 recursively scan the value being stored. */
4619 if ((GET_CODE (testreg) == PARALLEL
4620 && GET_MODE (testreg) == BLKmode)
4621 || (GET_CODE (testreg) == REG
4622 && (regno = REGNO (testreg), ! (regno == FRAME_POINTER_REGNUM
4623 && (! reload_completed || frame_pointer_needed)))
4624 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4625 && ! (regno == HARD_FRAME_POINTER_REGNUM
4626 && (! reload_completed || frame_pointer_needed))
4628 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4629 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4632 /* We used to exclude global_regs here, but that seems wrong.
4633 Storing in them is like storing in mem. */
4635 mark_used_regs (needed, live, SET_SRC (x), flags, insn);
4637 mark_used_regs (needed, live, SET_DEST (x), flags, insn);
4644 /* ??? This info should have been gotten from mark_regs_live_at_end,
4645 as applied to the EXIT block, and propagated along the edge that
4646 connects this block to the EXIT. */
4650 case UNSPEC_VOLATILE:
4654 /* Traditional and volatile asm instructions must be considered to use
4655 and clobber all hard registers, all pseudo-registers and all of
4656 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
4658 Consider for instance a volatile asm that changes the fpu rounding
4659 mode. An insn should not be moved across this even if it only uses
4660 pseudo-regs because it might give an incorrectly rounded result.
4662 ?!? Unfortunately, marking all hard registers as live causes massive
4663 problems for the register allocator and marking all pseudos as live
4664 creates mountains of uninitialized variable warnings.
4666 So for now, just clear the memory set list and mark any regs
4667 we can find in ASM_OPERANDS as used. */
4668 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
4669 free_EXPR_LIST_list (&mem_set_list);
4671 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
4672 We can not just fall through here since then we would be confused
4673 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
4674 traditional asms unlike their normal usage. */
4675 if (code == ASM_OPERANDS)
4679 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
4680 mark_used_regs (needed, live, ASM_OPERANDS_INPUT (x, j),
4691 /* Recursively scan the operands of this expression. */
4694 register const char *fmt = GET_RTX_FORMAT (code);
4697 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4701 /* Tail recursive case: save a function call level. */
4707 mark_used_regs (needed, live, XEXP (x, i), flags, insn);
4709 else if (fmt[i] == 'E')
4712 for (j = 0; j < XVECLEN (x, i); j++)
4713 mark_used_regs (needed, live, XVECEXP (x, i, j), flags, insn);
4722 try_pre_increment_1 (insn)
4725 /* Find the next use of this reg. If in same basic block,
4726 make it do pre-increment or pre-decrement if appropriate. */
4727 rtx x = single_set (insn);
4728 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
4729 * INTVAL (XEXP (SET_SRC (x), 1)));
4730 int regno = REGNO (SET_DEST (x));
4731 rtx y = reg_next_use[regno];
4733 && BLOCK_NUM (y) == BLOCK_NUM (insn)
4734 /* Don't do this if the reg dies, or gets set in y; a standard addressing
4735 mode would be better. */
4736 && ! dead_or_set_p (y, SET_DEST (x))
4737 && try_pre_increment (y, SET_DEST (x), amount))
4739 /* We have found a suitable auto-increment
4740 and already changed insn Y to do it.
4741 So flush this increment-instruction. */
4742 PUT_CODE (insn, NOTE);
4743 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
4744 NOTE_SOURCE_FILE (insn) = 0;
4745 /* Count a reference to this reg for the increment
4746 insn we are deleting. When a reg is incremented.
4747 spilling it is worse, so we want to make that
4749 if (regno >= FIRST_PSEUDO_REGISTER)
4751 REG_N_REFS (regno) += loop_depth + 1;
4752 REG_N_SETS (regno)++;
4759 /* Try to change INSN so that it does pre-increment or pre-decrement
4760 addressing on register REG in order to add AMOUNT to REG.
4761 AMOUNT is negative for pre-decrement.
4762 Returns 1 if the change could be made.
4763 This checks all about the validity of the result of modifying INSN. */
4766 try_pre_increment (insn, reg, amount)
4768 HOST_WIDE_INT amount;
4772 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4773 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4775 /* Nonzero if we can try to make a post-increment or post-decrement.
4776 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4777 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4778 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4781 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4784 /* From the sign of increment, see which possibilities are conceivable
4785 on this target machine. */
4786 if (HAVE_PRE_INCREMENT && amount > 0)
4788 if (HAVE_POST_INCREMENT && amount > 0)
4791 if (HAVE_PRE_DECREMENT && amount < 0)
4793 if (HAVE_POST_DECREMENT && amount < 0)
4796 if (! (pre_ok || post_ok))
4799 /* It is not safe to add a side effect to a jump insn
4800 because if the incremented register is spilled and must be reloaded
4801 there would be no way to store the incremented value back in memory. */
4803 if (GET_CODE (insn) == JUMP_INSN)
4808 use = find_use_as_address (PATTERN (insn), reg, 0);
4809 if (post_ok && (use == 0 || use == (rtx) 1))
4811 use = find_use_as_address (PATTERN (insn), reg, -amount);
4815 if (use == 0 || use == (rtx) 1)
4818 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4821 /* See if this combination of instruction and addressing mode exists. */
4822 if (! validate_change (insn, &XEXP (use, 0),
4823 gen_rtx_fmt_e (amount > 0
4824 ? (do_post ? POST_INC : PRE_INC)
4825 : (do_post ? POST_DEC : PRE_DEC),
4829 /* Record that this insn now has an implicit side effect on X. */
4830 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4834 #endif /* AUTO_INC_DEC */
4836 /* Find the place in the rtx X where REG is used as a memory address.
4837 Return the MEM rtx that so uses it.
4838 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4839 (plus REG (const_int PLUSCONST)).
4841 If such an address does not appear, return 0.
4842 If REG appears more than once, or is used other than in such an address,
4846 find_use_as_address (x, reg, plusconst)
4849 HOST_WIDE_INT plusconst;
4851 enum rtx_code code = GET_CODE (x);
4852 const char *fmt = GET_RTX_FORMAT (code);
4854 register rtx value = 0;
4857 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4860 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4861 && XEXP (XEXP (x, 0), 0) == reg
4862 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4863 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4866 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4868 /* If REG occurs inside a MEM used in a bit-field reference,
4869 that is unacceptable. */
4870 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4871 return (rtx) (HOST_WIDE_INT) 1;
4875 return (rtx) (HOST_WIDE_INT) 1;
4877 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4881 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4885 return (rtx) (HOST_WIDE_INT) 1;
4887 else if (fmt[i] == 'E')
4890 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4892 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4896 return (rtx) (HOST_WIDE_INT) 1;
4904 /* Write information about registers and basic blocks into FILE.
4905 This is part of making a debugging dump. */
4908 dump_flow_info (file)
4912 static const char * const reg_class_names[] = REG_CLASS_NAMES;
4914 fprintf (file, "%d registers.\n", max_regno);
4915 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
4918 enum reg_class class, altclass;
4919 fprintf (file, "\nRegister %d used %d times across %d insns",
4920 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
4921 if (REG_BASIC_BLOCK (i) >= 0)
4922 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
4924 fprintf (file, "; set %d time%s", REG_N_SETS (i),
4925 (REG_N_SETS (i) == 1) ? "" : "s");
4926 if (REG_USERVAR_P (regno_reg_rtx[i]))
4927 fprintf (file, "; user var");
4928 if (REG_N_DEATHS (i) != 1)
4929 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
4930 if (REG_N_CALLS_CROSSED (i) == 1)
4931 fprintf (file, "; crosses 1 call");
4932 else if (REG_N_CALLS_CROSSED (i))
4933 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
4934 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
4935 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
4936 class = reg_preferred_class (i);
4937 altclass = reg_alternate_class (i);
4938 if (class != GENERAL_REGS || altclass != ALL_REGS)
4940 if (altclass == ALL_REGS || class == ALL_REGS)
4941 fprintf (file, "; pref %s", reg_class_names[(int) class]);
4942 else if (altclass == NO_REGS)
4943 fprintf (file, "; %s or none", reg_class_names[(int) class]);
4945 fprintf (file, "; pref %s, else %s",
4946 reg_class_names[(int) class],
4947 reg_class_names[(int) altclass]);
4949 if (REGNO_POINTER_FLAG (i))
4950 fprintf (file, "; pointer");
4951 fprintf (file, ".\n");
4954 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
4955 for (i = 0; i < n_basic_blocks; i++)
4957 register basic_block bb = BASIC_BLOCK (i);
4961 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d.\n",
4962 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth);
4964 fprintf (file, "Predecessors: ");
4965 for (e = bb->pred; e ; e = e->pred_next)
4966 dump_edge_info (file, e, 0);
4968 fprintf (file, "\nSuccessors: ");
4969 for (e = bb->succ; e ; e = e->succ_next)
4970 dump_edge_info (file, e, 1);
4972 fprintf (file, "\nRegisters live at start:");
4973 if (bb->global_live_at_start)
4975 for (regno = 0; regno < max_regno; regno++)
4976 if (REGNO_REG_SET_P (bb->global_live_at_start, regno))
4977 fprintf (file, " %d", regno);
4980 fprintf (file, " n/a");
4982 fprintf (file, "\nRegisters live at end:");
4983 if (bb->global_live_at_end)
4985 for (regno = 0; regno < max_regno; regno++)
4986 if (REGNO_REG_SET_P (bb->global_live_at_end, regno))
4987 fprintf (file, " %d", regno);
4990 fprintf (file, " n/a");
5001 dump_flow_info (stderr);
5005 dump_edge_info (file, e, do_succ)
5010 basic_block side = (do_succ ? e->dest : e->src);
5012 if (side == ENTRY_BLOCK_PTR)
5013 fputs (" ENTRY", file);
5014 else if (side == EXIT_BLOCK_PTR)
5015 fputs (" EXIT", file);
5017 fprintf (file, " %d", side->index);
5021 static const char * const bitnames[] = {
5022 "fallthru", "crit", "ab", "abcall", "eh", "fake"
5025 int i, flags = e->flags;
5029 for (i = 0; flags; i++)
5030 if (flags & (1 << i))
5036 if (i < (int)(sizeof (bitnames) / sizeof (*bitnames)))
5037 fputs (bitnames[i], file);
5039 fprintf (file, "%d", i);
5047 /* Like print_rtl, but also print out live information for the start of each
5051 print_rtl_with_bb (outf, rtx_first)
5055 register rtx tmp_rtx;
5058 fprintf (outf, "(nil)\n");
5062 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
5063 int max_uid = get_max_uid ();
5064 basic_block *start = (basic_block *)
5065 xcalloc (max_uid, sizeof (basic_block));
5066 basic_block *end = (basic_block *)
5067 xcalloc (max_uid, sizeof (basic_block));
5068 enum bb_state *in_bb_p = (enum bb_state *)
5069 xcalloc (max_uid, sizeof (enum bb_state));
5071 for (i = n_basic_blocks - 1; i >= 0; i--)
5073 basic_block bb = BASIC_BLOCK (i);
5076 start[INSN_UID (bb->head)] = bb;
5077 end[INSN_UID (bb->end)] = bb;
5078 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
5080 enum bb_state state = IN_MULTIPLE_BB;
5081 if (in_bb_p[INSN_UID(x)] == NOT_IN_BB)
5083 in_bb_p[INSN_UID(x)] = state;
5090 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
5095 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
5097 fprintf (outf, ";; Start of basic block %d, registers live:",
5100 EXECUTE_IF_SET_IN_REG_SET (bb->global_live_at_start, 0, i,
5102 fprintf (outf, " %d", i);
5103 if (i < FIRST_PSEUDO_REGISTER)
5104 fprintf (outf, " [%s]",
5110 if (in_bb_p[INSN_UID(tmp_rtx)] == NOT_IN_BB
5111 && GET_CODE (tmp_rtx) != NOTE
5112 && GET_CODE (tmp_rtx) != BARRIER
5114 fprintf (outf, ";; Insn is not within a basic block\n");
5115 else if (in_bb_p[INSN_UID(tmp_rtx)] == IN_MULTIPLE_BB)
5116 fprintf (outf, ";; Insn is in multiple basic blocks\n");
5118 did_output = print_rtl_single (outf, tmp_rtx);
5120 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
5121 fprintf (outf, ";; End of basic block %d\n", bb->index);
5132 if (current_function_epilogue_delay_list != 0)
5134 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
5135 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
5136 tmp_rtx = XEXP (tmp_rtx, 1))
5137 print_rtl_single (outf, XEXP (tmp_rtx, 0));
5141 /* Compute dominator relationships using new flow graph structures. */
5143 compute_flow_dominators (dominators, post_dominators)
5144 sbitmap *dominators;
5145 sbitmap *post_dominators;
5148 sbitmap *temp_bitmap;
5150 basic_block *worklist, *tos;
5152 /* Allocate a worklist array/queue. Entries are only added to the
5153 list if they were not already on the list. So the size is
5154 bounded by the number of basic blocks. */
5155 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block)
5158 temp_bitmap = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
5159 sbitmap_vector_zero (temp_bitmap, n_basic_blocks);
5163 /* The optimistic setting of dominators requires us to put every
5164 block on the work list initially. */
5165 for (bb = 0; bb < n_basic_blocks; bb++)
5167 *tos++ = BASIC_BLOCK (bb);
5168 BASIC_BLOCK (bb)->aux = BASIC_BLOCK (bb);
5171 /* We want a maximal solution, so initially assume everything dominates
5173 sbitmap_vector_ones (dominators, n_basic_blocks);
5175 /* Mark successors of the entry block so we can identify them below. */
5176 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
5177 e->dest->aux = ENTRY_BLOCK_PTR;
5179 /* Iterate until the worklist is empty. */
5180 while (tos != worklist)
5182 /* Take the first entry off the worklist. */
5183 basic_block b = *--tos;
5186 /* Compute the intersection of the dominators of all the
5189 If one of the predecessor blocks is the ENTRY block, then the
5190 intersection of the dominators of the predecessor blocks is
5191 defined as the null set. We can identify such blocks by the
5192 special value in the AUX field in the block structure. */
5193 if (b->aux == ENTRY_BLOCK_PTR)
5195 /* Do not clear the aux field for blocks which are
5196 successors of the ENTRY block. That way we we never
5197 add them to the worklist again.
5199 The intersect of dominators of the preds of this block is
5200 defined as the null set. */
5201 sbitmap_zero (temp_bitmap[bb]);
5205 /* Clear the aux field of this block so it can be added to
5206 the worklist again if necessary. */
5208 sbitmap_intersection_of_preds (temp_bitmap[bb], dominators, bb);
5211 /* Make sure each block always dominates itself. */
5212 SET_BIT (temp_bitmap[bb], bb);
5214 /* If the out state of this block changed, then we need to
5215 add the successors of this block to the worklist if they
5216 are not already on the worklist. */
5217 if (sbitmap_a_and_b (dominators[bb], dominators[bb], temp_bitmap[bb]))
5219 for (e = b->succ; e; e = e->succ_next)
5221 if (!e->dest->aux && e->dest != EXIT_BLOCK_PTR)
5231 if (post_dominators)
5233 /* The optimistic setting of dominators requires us to put every
5234 block on the work list initially. */
5235 for (bb = 0; bb < n_basic_blocks; bb++)
5237 *tos++ = BASIC_BLOCK (bb);
5238 BASIC_BLOCK (bb)->aux = BASIC_BLOCK (bb);
5241 /* We want a maximal solution, so initially assume everything post
5242 dominates everything else. */
5243 sbitmap_vector_ones (post_dominators, n_basic_blocks);
5245 /* Mark predecessors of the exit block so we can identify them below. */
5246 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
5247 e->src->aux = EXIT_BLOCK_PTR;
5249 /* Iterate until the worklist is empty. */
5250 while (tos != worklist)
5252 /* Take the first entry off the worklist. */
5253 basic_block b = *--tos;
5256 /* Compute the intersection of the post dominators of all the
5259 If one of the successor blocks is the EXIT block, then the
5260 intersection of the dominators of the successor blocks is
5261 defined as the null set. We can identify such blocks by the
5262 special value in the AUX field in the block structure. */
5263 if (b->aux == EXIT_BLOCK_PTR)
5265 /* Do not clear the aux field for blocks which are
5266 predecessors of the EXIT block. That way we we never
5267 add them to the worklist again.
5269 The intersect of dominators of the succs of this block is
5270 defined as the null set. */
5271 sbitmap_zero (temp_bitmap[bb]);
5275 /* Clear the aux field of this block so it can be added to
5276 the worklist again if necessary. */
5278 sbitmap_intersection_of_succs (temp_bitmap[bb],
5279 post_dominators, bb);
5282 /* Make sure each block always post dominates itself. */
5283 SET_BIT (temp_bitmap[bb], bb);
5285 /* If the out state of this block changed, then we need to
5286 add the successors of this block to the worklist if they
5287 are not already on the worklist. */
5288 if (sbitmap_a_and_b (post_dominators[bb],
5289 post_dominators[bb],
5292 for (e = b->pred; e; e = e->pred_next)
5294 if (!e->src->aux && e->src != ENTRY_BLOCK_PTR)
5306 /* Given DOMINATORS, compute the immediate dominators into IDOM. */
5309 compute_immediate_dominators (idom, dominators)
5311 sbitmap *dominators;
5316 tmp = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
5318 /* Begin with tmp(n) = dom(n) - { n }. */
5319 for (b = n_basic_blocks; --b >= 0; )
5321 sbitmap_copy (tmp[b], dominators[b]);
5322 RESET_BIT (tmp[b], b);
5325 /* Subtract out all of our dominator's dominators. */
5326 for (b = n_basic_blocks; --b >= 0; )
5328 sbitmap tmp_b = tmp[b];
5331 for (s = n_basic_blocks; --s >= 0; )
5332 if (TEST_BIT (tmp_b, s))
5333 sbitmap_difference (tmp_b, tmp_b, tmp[s]);
5336 /* Find the one bit set in the bitmap and put it in the output array. */
5337 for (b = n_basic_blocks; --b >= 0; )
5340 EXECUTE_IF_SET_IN_SBITMAP (tmp[b], 0, t, { idom[b] = t; });
5343 sbitmap_vector_free (tmp);
5346 /* Count for a single SET rtx, X. */
5349 count_reg_sets_1 (x)
5353 register rtx reg = SET_DEST (x);
5355 /* Find the register that's set/clobbered. */
5356 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
5357 || GET_CODE (reg) == SIGN_EXTRACT
5358 || GET_CODE (reg) == STRICT_LOW_PART)
5359 reg = XEXP (reg, 0);
5361 if (GET_CODE (reg) == PARALLEL
5362 && GET_MODE (reg) == BLKmode)
5365 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
5366 count_reg_sets_1 (XVECEXP (reg, 0, i));
5370 if (GET_CODE (reg) == REG)
5372 regno = REGNO (reg);
5373 if (regno >= FIRST_PSEUDO_REGISTER)
5375 /* Count (weighted) references, stores, etc. This counts a
5376 register twice if it is modified, but that is correct. */
5377 REG_N_SETS (regno)++;
5378 REG_N_REFS (regno) += loop_depth + 1;
5383 /* Increment REG_N_SETS for each SET or CLOBBER found in X; also increment
5384 REG_N_REFS by the current loop depth for each SET or CLOBBER found. */
5390 register RTX_CODE code = GET_CODE (x);
5392 if (code == SET || code == CLOBBER)
5393 count_reg_sets_1 (x);
5394 else if (code == PARALLEL)
5397 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
5399 code = GET_CODE (XVECEXP (x, 0, i));
5400 if (code == SET || code == CLOBBER)
5401 count_reg_sets_1 (XVECEXP (x, 0, i));
5406 /* Increment REG_N_REFS by the current loop depth each register reference
5410 count_reg_references (x)
5413 register RTX_CODE code;
5416 code = GET_CODE (x);
5436 /* If we are clobbering a MEM, mark any registers inside the address
5438 if (GET_CODE (XEXP (x, 0)) == MEM)
5439 count_reg_references (XEXP (XEXP (x, 0), 0));
5443 /* While we're here, optimize this case. */
5446 /* In case the SUBREG is not of a register, don't optimize */
5447 if (GET_CODE (x) != REG)
5449 count_reg_references (x);
5453 /* ... fall through ... */
5456 if (REGNO (x) >= FIRST_PSEUDO_REGISTER)
5457 REG_N_REFS (REGNO (x)) += loop_depth + 1;
5462 register rtx testreg = SET_DEST (x);
5465 /* If storing into MEM, don't show it as being used. But do
5466 show the address as being used. */
5467 if (GET_CODE (testreg) == MEM)
5469 count_reg_references (XEXP (testreg, 0));
5470 count_reg_references (SET_SRC (x));
5474 /* Storing in STRICT_LOW_PART is like storing in a reg
5475 in that this SET might be dead, so ignore it in TESTREG.
5476 but in some other ways it is like using the reg.
5478 Storing in a SUBREG or a bit field is like storing the entire
5479 register in that if the register's value is not used
5480 then this SET is not needed. */
5481 while (GET_CODE (testreg) == STRICT_LOW_PART
5482 || GET_CODE (testreg) == ZERO_EXTRACT
5483 || GET_CODE (testreg) == SIGN_EXTRACT
5484 || GET_CODE (testreg) == SUBREG)
5486 /* Modifying a single register in an alternate mode
5487 does not use any of the old value. But these other
5488 ways of storing in a register do use the old value. */
5489 if (GET_CODE (testreg) == SUBREG
5490 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5495 testreg = XEXP (testreg, 0);
5498 /* If this is a store into a register,
5499 recursively scan the value being stored. */
5501 if ((GET_CODE (testreg) == PARALLEL
5502 && GET_MODE (testreg) == BLKmode)
5503 || GET_CODE (testreg) == REG)
5505 count_reg_references (SET_SRC (x));
5507 count_reg_references (SET_DEST (x));
5517 /* Recursively scan the operands of this expression. */
5520 register const char *fmt = GET_RTX_FORMAT (code);
5523 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5527 /* Tail recursive case: save a function call level. */
5533 count_reg_references (XEXP (x, i));
5535 else if (fmt[i] == 'E')
5538 for (j = 0; j < XVECLEN (x, i); j++)
5539 count_reg_references (XVECEXP (x, i, j));
5545 /* Recompute register set/reference counts immediately prior to register
5548 This avoids problems with set/reference counts changing to/from values
5549 which have special meanings to the register allocators.
5551 Additionally, the reference counts are the primary component used by the
5552 register allocators to prioritize pseudos for allocation to hard regs.
5553 More accurate reference counts generally lead to better register allocation.
5555 F is the first insn to be scanned.
5557 LOOP_STEP denotes how much loop_depth should be incremented per
5558 loop nesting level in order to increase the ref count more for
5559 references in a loop.
5561 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
5562 possibly other information which is used by the register allocators. */
5565 recompute_reg_usage (f, loop_step)
5566 rtx f ATTRIBUTE_UNUSED;
5567 int loop_step ATTRIBUTE_UNUSED;
5573 /* Clear out the old data. */
5574 max_reg = max_reg_num ();
5575 for (i = FIRST_PSEUDO_REGISTER; i < max_reg; i++)
5581 /* Scan each insn in the chain and count how many times each register is
5583 for (index = 0; index < n_basic_blocks; index++)
5585 basic_block bb = BASIC_BLOCK (index);
5586 loop_depth = bb->loop_depth;
5587 for (insn = bb->head; insn; insn = NEXT_INSN (insn))
5589 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
5593 /* This call will increment REG_N_SETS for each SET or CLOBBER
5594 of a register in INSN. It will also increment REG_N_REFS
5595 by the loop depth for each set of a register in INSN. */
5596 count_reg_sets (PATTERN (insn));
5598 /* count_reg_sets does not detect autoincrement address modes, so
5599 detect them here by looking at the notes attached to INSN. */
5600 for (links = REG_NOTES (insn); links; links = XEXP (links, 1))
5602 if (REG_NOTE_KIND (links) == REG_INC)
5603 /* Count (weighted) references, stores, etc. This counts a
5604 register twice if it is modified, but that is correct. */
5605 REG_N_SETS (REGNO (XEXP (links, 0)))++;
5608 /* This call will increment REG_N_REFS by the current loop depth for
5609 each reference to a register in INSN. */
5610 count_reg_references (PATTERN (insn));
5612 /* count_reg_references will not include counts for arguments to
5613 function calls, so detect them here by examining the
5614 CALL_INSN_FUNCTION_USAGE data. */
5615 if (GET_CODE (insn) == CALL_INSN)
5619 for (note = CALL_INSN_FUNCTION_USAGE (insn);
5621 note = XEXP (note, 1))
5622 if (GET_CODE (XEXP (note, 0)) == USE)
5623 count_reg_references (XEXP (XEXP (note, 0), 0));
5626 if (insn == bb->end)
5632 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
5633 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
5634 of the number of registers that died. */
5637 count_or_remove_death_notes (blocks, kill)
5643 for (i = n_basic_blocks - 1; i >= 0; --i)
5648 if (blocks && ! TEST_BIT (blocks, i))
5651 bb = BASIC_BLOCK (i);
5653 for (insn = bb->head; ; insn = NEXT_INSN (insn))
5655 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
5657 rtx *pprev = ®_NOTES (insn);
5662 switch (REG_NOTE_KIND (link))
5665 if (GET_CODE (XEXP (link, 0)) == REG)
5667 rtx reg = XEXP (link, 0);
5670 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
5673 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
5681 rtx next = XEXP (link, 1);
5682 free_EXPR_LIST_node (link);
5683 *pprev = link = next;
5689 pprev = &XEXP (link, 1);
5696 if (insn == bb->end)
5704 /* Record INSN's block as BB. */
5707 set_block_for_insn (insn, bb)
5711 size_t uid = INSN_UID (insn);
5712 if (uid >= basic_block_for_insn->num_elements)
5716 /* Add one-eighth the size so we don't keep calling xrealloc. */
5717 new_size = uid + (uid + 7) / 8;
5719 VARRAY_GROW (basic_block_for_insn, new_size);
5721 VARRAY_BB (basic_block_for_insn, uid) = bb;
5724 /* Record INSN's block number as BB. */
5725 /* ??? This has got to go. */
5728 set_block_num (insn, bb)
5732 set_block_for_insn (insn, BASIC_BLOCK (bb));
5735 /* Verify the CFG consistency. This function check some CFG invariants and
5736 aborts when something is wrong. Hope that this function will help to
5737 convert many optimization passes to preserve CFG consistent.
5739 Currently it does following checks:
5741 - test head/end pointers
5742 - overlapping of basic blocks
5743 - edge list corectness
5744 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
5745 - tails of basic blocks (ensure that boundary is necesary)
5746 - scans body of the basic block for JUMP_INSN, CODE_LABEL
5747 and NOTE_INSN_BASIC_BLOCK
5748 - check that all insns are in the basic blocks
5749 (except the switch handling code, barriers and notes)
5751 In future it can be extended check a lot of other stuff as well
5752 (reachability of basic blocks, life information, etc. etc.). */
5757 const int max_uid = get_max_uid ();
5758 const rtx rtx_first = get_insns ();
5759 basic_block *bb_info;
5763 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
5765 /* First pass check head/end pointers and set bb_info array used by
5767 for (i = n_basic_blocks - 1; i >= 0; i--)
5769 basic_block bb = BASIC_BLOCK (i);
5771 /* Check the head pointer and make sure that it is pointing into
5773 for (x = rtx_first; x != NULL_RTX; x = NEXT_INSN (x))
5778 error ("Head insn %d for block %d not found in the insn stream.",
5779 INSN_UID (bb->head), bb->index);
5783 /* Check the end pointer and make sure that it is pointing into
5785 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
5787 if (bb_info[INSN_UID (x)] != NULL)
5789 error ("Insn %d is in multiple basic blocks (%d and %d)",
5790 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
5793 bb_info[INSN_UID (x)] = bb;
5800 error ("End insn %d for block %d not found in the insn stream.",
5801 INSN_UID (bb->end), bb->index);
5806 /* Now check the basic blocks (boundaries etc.) */
5807 for (i = n_basic_blocks - 1; i >= 0; i--)
5809 basic_block bb = BASIC_BLOCK (i);
5810 /* Check corectness of edge lists */
5818 fprintf (stderr, "verify_flow_info: Basic block %d succ edge is corrupted\n",
5820 fprintf (stderr, "Predecessor: ");
5821 dump_edge_info (stderr, e, 0);
5822 fprintf (stderr, "\nSuccessor: ");
5823 dump_edge_info (stderr, e, 1);
5827 if (e->dest != EXIT_BLOCK_PTR)
5829 edge e2 = e->dest->pred;
5830 while (e2 && e2 != e)
5834 error ("Basic block %i edge lists are corrupted", bb->index);
5846 error ("Basic block %d pred edge is corrupted", bb->index);
5847 fputs ("Predecessor: ", stderr);
5848 dump_edge_info (stderr, e, 0);
5849 fputs ("\nSuccessor: ", stderr);
5850 dump_edge_info (stderr, e, 1);
5851 fputc ('\n', stderr);
5854 if (e->src != ENTRY_BLOCK_PTR)
5856 edge e2 = e->src->succ;
5857 while (e2 && e2 != e)
5861 error ("Basic block %i edge lists are corrupted", bb->index);
5868 /* OK pointers are correct. Now check the header of basic
5869 block. It ought to contain optional CODE_LABEL followed
5870 by NOTE_BASIC_BLOCK. */
5872 if (GET_CODE (x) == CODE_LABEL)
5876 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
5882 if (GET_CODE (x) != NOTE
5883 || NOTE_LINE_NUMBER (x) != NOTE_INSN_BASIC_BLOCK
5884 || NOTE_BASIC_BLOCK (x) != bb)
5886 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
5893 /* Do checks for empty blocks here */
5900 if (GET_CODE (x) == NOTE
5901 && NOTE_LINE_NUMBER (x) == NOTE_INSN_BASIC_BLOCK)
5903 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
5904 INSN_UID (x), bb->index);
5911 if (GET_CODE (x) == JUMP_INSN
5912 || GET_CODE (x) == CODE_LABEL
5913 || GET_CODE (x) == BARRIER)
5915 error ("In basic block %d:", bb->index);
5916 fatal_insn ("Flow control insn inside a basic block", x);
5927 if (!bb_info[INSN_UID (x)])
5929 switch (GET_CODE (x))
5936 /* An addr_vec is placed outside any block block. */
5938 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
5939 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
5940 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
5945 /* But in any case, non-deletable labels can appear anywhere. */
5949 fatal_insn ("Insn outside basic block", x);
5963 /* Functions to access an edge list with a vector representation.
5964 Enough data is kept such that given an index number, the
5965 pred and succ that edge reprsents can be determined, or
5966 given a pred and a succ, it's index number can be returned.
5967 This allows algorithms which comsume a lot of memory to
5968 represent the normally full matrix of edge (pred,succ) with a
5969 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
5970 wasted space in the client code due to sparse flow graphs. */
5972 /* This functions initializes the edge list. Basically the entire
5973 flowgraph is processed, and all edges are assigned a number,
5974 and the data structure is filed in. */
5978 struct edge_list *elist;
5984 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
5988 /* Determine the number of edges in the flow graph by counting successor
5989 edges on each basic block. */
5990 for (x = 0; x < n_basic_blocks; x++)
5992 basic_block bb = BASIC_BLOCK (x);
5994 for (e = bb->succ; e; e = e->succ_next)
5997 /* Don't forget successors of the entry block. */
5998 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6001 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
6002 elist->num_blocks = block_count;
6003 elist->num_edges = num_edges;
6004 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
6008 /* Follow successors of the entry block, and register these edges. */
6009 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6011 elist->index_to_edge[num_edges] = e;
6015 for (x = 0; x < n_basic_blocks; x++)
6017 basic_block bb = BASIC_BLOCK (x);
6019 /* Follow all successors of blocks, and register these edges. */
6020 for (e = bb->succ; e; e = e->succ_next)
6022 elist->index_to_edge[num_edges] = e;
6029 /* This function free's memory associated with an edge list. */
6031 free_edge_list (elist)
6032 struct edge_list *elist;
6036 free (elist->index_to_edge);
6041 /* This function provides debug output showing an edge list. */
6043 print_edge_list (f, elist)
6045 struct edge_list *elist;
6048 fprintf(f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
6049 elist->num_blocks - 2, elist->num_edges);
6051 for (x = 0; x < elist->num_edges; x++)
6053 fprintf (f, " %-4d - edge(", x);
6054 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
6055 fprintf (f,"entry,");
6057 fprintf (f,"%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
6059 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
6060 fprintf (f,"exit)\n");
6062 fprintf (f,"%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
6066 /* This function provides an internal consistancy check of an edge list,
6067 verifying that all edges are present, and that there are no
6070 verify_edge_list (f, elist)
6072 struct edge_list *elist;
6074 int x, pred, succ, index;
6077 for (x = 0; x < n_basic_blocks; x++)
6079 basic_block bb = BASIC_BLOCK (x);
6081 for (e = bb->succ; e; e = e->succ_next)
6083 pred = e->src->index;
6084 succ = e->dest->index;
6085 index = EDGE_INDEX (elist, e->src, e->dest);
6086 if (index == EDGE_INDEX_NO_EDGE)
6088 fprintf (f, "*p* No index for edge from %d to %d\n",pred, succ);
6091 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
6092 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
6093 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
6094 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
6095 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
6096 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
6099 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6101 pred = e->src->index;
6102 succ = e->dest->index;
6103 index = EDGE_INDEX (elist, e->src, e->dest);
6104 if (index == EDGE_INDEX_NO_EDGE)
6106 fprintf (f, "*p* No index for edge from %d to %d\n",pred, succ);
6109 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
6110 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
6111 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
6112 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
6113 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
6114 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
6116 /* We've verified that all the edges are in the list, no lets make sure
6117 there are no spurious edges in the list. */
6119 for (pred = 0 ; pred < n_basic_blocks; pred++)
6120 for (succ = 0 ; succ < n_basic_blocks; succ++)
6122 basic_block p = BASIC_BLOCK (pred);
6123 basic_block s = BASIC_BLOCK (succ);
6127 for (e = p->succ; e; e = e->succ_next)
6133 for (e = s->pred; e; e = e->pred_next)
6139 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
6140 == EDGE_INDEX_NO_EDGE && found_edge != 0)
6141 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
6143 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
6144 != EDGE_INDEX_NO_EDGE && found_edge == 0)
6145 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
6146 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
6147 BASIC_BLOCK (succ)));
6149 for (succ = 0 ; succ < n_basic_blocks; succ++)
6151 basic_block p = ENTRY_BLOCK_PTR;
6152 basic_block s = BASIC_BLOCK (succ);
6156 for (e = p->succ; e; e = e->succ_next)
6162 for (e = s->pred; e; e = e->pred_next)
6168 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
6169 == EDGE_INDEX_NO_EDGE && found_edge != 0)
6170 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
6172 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
6173 != EDGE_INDEX_NO_EDGE && found_edge == 0)
6174 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
6175 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
6176 BASIC_BLOCK (succ)));
6178 for (pred = 0 ; pred < n_basic_blocks; pred++)
6180 basic_block p = BASIC_BLOCK (pred);
6181 basic_block s = EXIT_BLOCK_PTR;
6185 for (e = p->succ; e; e = e->succ_next)
6191 for (e = s->pred; e; e = e->pred_next)
6197 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
6198 == EDGE_INDEX_NO_EDGE && found_edge != 0)
6199 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
6201 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
6202 != EDGE_INDEX_NO_EDGE && found_edge == 0)
6203 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
6204 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
6209 /* This routine will determine what, if any, edge there is between
6210 a specified predecessor and successor. */
6213 find_edge_index (edge_list, pred, succ)
6214 struct edge_list *edge_list;
6215 basic_block pred, succ;
6218 for (x = 0; x < NUM_EDGES (edge_list); x++)
6220 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
6221 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
6224 return (EDGE_INDEX_NO_EDGE);
6227 /* This function will remove an edge from the flow graph. */
6232 edge last_pred = NULL;
6233 edge last_succ = NULL;
6235 basic_block src, dest;
6238 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
6244 last_succ->succ_next = e->succ_next;
6246 src->succ = e->succ_next;
6248 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
6254 last_pred->pred_next = e->pred_next;
6256 dest->pred = e->pred_next;
6262 /* This routine will remove any fake successor edges for a basic block.
6263 When the edge is removed, it is also removed from whatever predecessor
6266 remove_fake_successors (bb)
6270 for (e = bb->succ; e ; )
6274 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
6279 /* This routine will remove all fake edges from the flow graph. If
6280 we remove all fake successors, it will automatically remove all
6281 fake predecessors. */
6283 remove_fake_edges ()
6287 for (x = 0; x < n_basic_blocks; x++)
6288 remove_fake_successors (BASIC_BLOCK (x));
6290 /* We've handled all successors except the entry block's. */
6291 remove_fake_successors (ENTRY_BLOCK_PTR);
6294 /* This functions will add a fake edge between any block which has no
6295 successors, and the exit block. Some data flow equations require these
6298 add_noreturn_fake_exit_edges ()
6302 for (x = 0; x < n_basic_blocks; x++)
6303 if (BASIC_BLOCK (x)->succ == NULL)
6304 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
6307 /* Dump the list of basic blocks in the bitmap NODES. */
6309 flow_nodes_print (str, nodes, file)
6311 const sbitmap nodes;
6316 fprintf (file, "%s { ", str);
6317 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
6318 fputs ("}\n", file);
6322 /* Dump the list of exiting edges in the array EDGES. */
6324 flow_exits_print (str, edges, num_edges, file)
6332 fprintf (file, "%s { ", str);
6333 for (i = 0; i < num_edges; i++)
6334 fprintf (file, "%d->%d ", edges[i]->src->index, edges[i]->dest->index);
6335 fputs ("}\n", file);
6339 /* Dump loop related CFG information. */
6341 flow_loops_cfg_dump (loops, file)
6342 const struct loops *loops;
6347 if (! loops->num || ! file || ! loops->cfg.dom)
6350 for (i = 0; i < n_basic_blocks; i++)
6354 fprintf (file, ";; %d succs { ", i);
6355 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
6356 fprintf (file, "%d ", succ->dest->index);
6357 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
6361 /* Dump the DFS node order. */
6362 if (loops->cfg.dfs_order)
6364 fputs (";; DFS order: ", file);
6365 for (i = 0; i < n_basic_blocks; i++)
6366 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
6372 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
6374 flow_loop_nested_p (outer, loop)
6378 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
6382 /* Dump the loop information specified by LOOPS to the stream FILE. */
6384 flow_loops_dump (loops, file, verbose)
6385 const struct loops *loops;
6392 num_loops = loops->num;
6393 if (! num_loops || ! file)
6396 fprintf (file, ";; %d loops found\n", num_loops);
6398 for (i = 0; i < num_loops; i++)
6400 struct loop *loop = &loops->array[i];
6402 fprintf (file, ";; loop %d (%d to %d):\n;; header %d, latch %d, pre-header %d, depth %d, level %d, outer %ld\n",
6403 i, INSN_UID (loop->header->head), INSN_UID (loop->latch->end),
6404 loop->header->index, loop->latch->index,
6405 loop->pre_header ? loop->pre_header->index : -1,
6406 loop->depth, loop->level,
6407 (long) (loop->outer ? (loop->outer - loops->array) : -1));
6408 fprintf (file, ";; %d", loop->num_nodes);
6409 flow_nodes_print (" nodes", loop->nodes, file);
6410 fprintf (file, ";; %d", loop->num_exits);
6411 flow_exits_print (" exits", loop->exits, loop->num_exits, file);
6417 for (j = 0; j < i; j++)
6419 struct loop *oloop = &loops->array[j];
6421 if (loop->header == oloop->header)
6426 smaller = loop->num_nodes < oloop->num_nodes;
6428 /* If the union of LOOP and OLOOP is different than
6429 the larger of LOOP and OLOOP then LOOP and OLOOP
6430 must be disjoint. */
6431 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
6432 smaller ? oloop : loop);
6433 fprintf (file, ";; loop header %d shared by loops %d, %d %s\n",
6434 loop->header->index, i, j,
6435 disjoint ? "disjoint" : "nested");
6442 /* Print diagnostics to compare our concept of a loop with
6443 what the loop notes say. */
6444 if (GET_CODE (PREV_INSN (loop->header->head)) != NOTE
6445 || NOTE_LINE_NUMBER (PREV_INSN (loop->header->head))
6446 != NOTE_INSN_LOOP_BEG)
6447 fprintf (file, ";; No NOTE_INSN_LOOP_BEG at %d\n",
6448 INSN_UID (PREV_INSN (loop->header->head)));
6449 if (GET_CODE (NEXT_INSN (loop->latch->end)) != NOTE
6450 || NOTE_LINE_NUMBER (NEXT_INSN (loop->latch->end))
6451 != NOTE_INSN_LOOP_END)
6452 fprintf (file, ";; No NOTE_INSN_LOOP_END at %d\n",
6453 INSN_UID (NEXT_INSN (loop->latch->end)));
6458 flow_loops_cfg_dump (loops, file);
6462 /* Free all the memory allocated for LOOPS. */
6464 flow_loops_free (loops)
6465 struct loops *loops;
6474 /* Free the loop descriptors. */
6475 for (i = 0; i < loops->num; i++)
6477 struct loop *loop = &loops->array[i];
6480 sbitmap_free (loop->nodes);
6484 free (loops->array);
6485 loops->array = NULL;
6488 sbitmap_vector_free (loops->cfg.dom);
6489 if (loops->cfg.dfs_order)
6490 free (loops->cfg.dfs_order);
6492 sbitmap_free (loops->shared_headers);
6497 /* Find the exits from the loop using the bitmap of loop nodes NODES
6498 and store in EXITS array. Return the number of exits from the
6501 flow_loop_exits_find (nodes, exits)
6502 const sbitmap nodes;
6511 /* Check all nodes within the loop to see if there are any
6512 successors not in the loop. Note that a node may have multiple
6515 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
6516 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
6518 basic_block dest = e->dest;
6520 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
6528 *exits = (edge *) xmalloc (num_exits * sizeof (edge *));
6530 /* Store all exiting edges into an array. */
6532 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
6533 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
6535 basic_block dest = e->dest;
6537 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
6538 (*exits)[num_exits++] = e;
6546 /* Find the nodes contained within the loop with header HEADER and
6547 latch LATCH and store in NODES. Return the number of nodes within
6550 flow_loop_nodes_find (header, latch, nodes)
6559 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
6562 /* Start with only the loop header in the set of loop nodes. */
6563 sbitmap_zero (nodes);
6564 SET_BIT (nodes, header->index);
6566 header->loop_depth++;
6568 /* Push the loop latch on to the stack. */
6569 if (! TEST_BIT (nodes, latch->index))
6571 SET_BIT (nodes, latch->index);
6572 latch->loop_depth++;
6574 stack[sp++] = latch;
6583 for (e = node->pred; e; e = e->pred_next)
6585 basic_block ancestor = e->src;
6587 /* If each ancestor not marked as part of loop, add to set of
6588 loop nodes and push on to stack. */
6589 if (ancestor != ENTRY_BLOCK_PTR
6590 && ! TEST_BIT (nodes, ancestor->index))
6592 SET_BIT (nodes, ancestor->index);
6593 ancestor->loop_depth++;
6595 stack[sp++] = ancestor;
6604 /* Compute the depth first search order and store in the array
6605 DFS_ORDER, marking the nodes visited in VISITED. Returns the
6606 number of nodes visited. */
6608 flow_depth_first_order_compute (dfs_order)
6617 /* Allocate stack for back-tracking up CFG. */
6618 stack = (edge *) xmalloc (n_basic_blocks * sizeof (edge));
6621 /* Allocate bitmap to track nodes that have been visited. */
6622 visited = sbitmap_alloc (n_basic_blocks);
6624 /* None of the nodes in the CFG have been visited yet. */
6625 sbitmap_zero (visited);
6627 /* Start with the first successor edge from the entry block. */
6628 e = ENTRY_BLOCK_PTR->succ;
6631 basic_block src = e->src;
6632 basic_block dest = e->dest;
6634 /* Mark that we have visited this node. */
6635 if (src != ENTRY_BLOCK_PTR)
6636 SET_BIT (visited, src->index);
6638 /* If this node has not been visited before, push the current
6639 edge on to the stack and proceed with the first successor
6640 edge of this node. */
6641 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index)
6649 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index)
6652 /* DEST has no successors (for example, a non-returning
6653 function is called) so do not push the current edge
6654 but carry on with its next successor. */
6655 dfs_order[dest->index] = n_basic_blocks - ++dfsnum;
6656 SET_BIT (visited, dest->index);
6659 while (! e->succ_next && src != ENTRY_BLOCK_PTR)
6661 dfs_order[src->index] = n_basic_blocks - ++dfsnum;
6663 /* Pop edge off stack. */
6671 sbitmap_free (visited);
6673 /* The number of nodes visited should not be greater than
6675 if (dfsnum > n_basic_blocks)
6678 /* There are some nodes left in the CFG that are unreachable. */
6679 if (dfsnum < n_basic_blocks)
6685 /* Return the block for the pre-header of the loop with header
6686 HEADER where DOM specifies the dominator information. Return NULL if
6687 there is no pre-header. */
6689 flow_loop_pre_header_find (header, dom)
6693 basic_block pre_header;
6696 /* If block p is a predecessor of the header and is the only block
6697 that the header does not dominate, then it is the pre-header. */
6699 for (e = header->pred; e; e = e->pred_next)
6701 basic_block node = e->src;
6703 if (node != ENTRY_BLOCK_PTR
6704 && ! TEST_BIT (dom[node->index], header->index))
6706 if (pre_header == NULL)
6710 /* There are multiple edges into the header from outside
6711 the loop so there is no pre-header block. */
6721 /* Add LOOP to the loop hierarchy tree so that it is a sibling or a
6722 descendant of ROOT. */
6724 flow_loop_tree_node_add (root, loop)
6733 for (outer = root; outer; outer = outer->next)
6735 if (flow_loop_nested_p (outer, loop))
6739 /* Add LOOP as a sibling or descendent of OUTER->INNER. */
6740 flow_loop_tree_node_add (outer->inner, loop);
6744 /* Add LOOP as child of OUTER. */
6745 outer->inner = loop;
6746 loop->outer = outer;
6752 /* Add LOOP as a sibling of ROOT. */
6753 loop->next = root->next;
6755 loop->outer = root->outer;
6759 /* Build the loop hierarchy tree for LOOPS. */
6761 flow_loops_tree_build (loops)
6762 struct loops *loops;
6767 num_loops = loops->num;
6771 /* Root the loop hierarchy tree with the first loop found.
6772 Since we used a depth first search this should be the
6774 loops->tree = &loops->array[0];
6775 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
6777 /* Add the remaining loops to the tree. */
6778 for (i = 1; i < num_loops; i++)
6779 flow_loop_tree_node_add (loops->tree, &loops->array[i]);
6783 /* Helper function to compute loop nesting depth and enclosed loop level
6784 for the natural loop specified by LOOP at the loop depth DEPTH.
6785 Returns the loop level. */
6787 flow_loop_level_compute (loop, depth)
6797 /* Traverse loop tree assigning depth and computing level as the
6798 maximum level of all the inner loops of this loop. The loop
6799 level is equivalent to the height of the loop in the loop tree
6800 and corresponds to the number of enclosed loop levels. */
6801 for (inner = loop->inner; inner; inner = inner->next)
6805 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
6810 loop->level = level;
6811 loop->depth = depth;
6816 /* Compute the loop nesting depth and enclosed loop level for the loop
6817 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
6821 flow_loops_level_compute (loops)
6822 struct loops *loops;
6824 return flow_loop_level_compute (loops->tree, 1);
6828 /* Find all the natural loops in the function and save in LOOPS structure
6829 and recalculate loop_depth information in basic block structures.
6830 Return the number of natural loops found. */
6833 flow_loops_find (loops)
6834 struct loops *loops;
6845 loops->array = NULL;
6849 /* Taking care of this degenerate case makes the rest of
6850 this code simpler. */
6851 if (n_basic_blocks == 0)
6854 /* Compute the dominators. */
6855 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
6856 compute_flow_dominators (dom, NULL);
6858 /* Count the number of loop edges (back edges). This should be the
6859 same as the number of natural loops. Also clear the loop_depth
6860 and as we work from inner->outer in a loop nest we call
6861 find_loop_nodes_find which will increment loop_depth for nodes
6862 within the current loop, which happens to enclose inner loops. */
6865 for (b = 0; b < n_basic_blocks; b++)
6867 BASIC_BLOCK (b)->loop_depth = 0;
6868 for (e = BASIC_BLOCK (b)->pred; e; e = e->pred_next)
6870 basic_block latch = e->src;
6872 /* Look for back edges where a predecessor is dominated
6873 by this block. A natural loop has a single entry
6874 node (header) that dominates all the nodes in the
6875 loop. It also has single back edge to the header
6876 from a latch node. Note that multiple natural loops
6877 may share the same header. */
6878 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
6885 /* Compute depth first search order of the CFG so that outer
6886 natural loops will be found before inner natural loops. */
6887 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
6888 flow_depth_first_order_compute (dfs_order);
6890 /* Allocate loop structures. */
6892 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
6894 headers = sbitmap_alloc (n_basic_blocks);
6895 sbitmap_zero (headers);
6897 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
6898 sbitmap_zero (loops->shared_headers);
6900 /* Find and record information about all the natural loops
6903 for (b = 0; b < n_basic_blocks; b++)
6907 /* Search the nodes of the CFG in DFS order that we can find
6908 outer loops first. */
6909 header = BASIC_BLOCK (dfs_order[b]);
6911 /* Look for all the possible latch blocks for this header. */
6912 for (e = header->pred; e; e = e->pred_next)
6914 basic_block latch = e->src;
6916 /* Look for back edges where a predecessor is dominated
6917 by this block. A natural loop has a single entry
6918 node (header) that dominates all the nodes in the
6919 loop. It also has single back edge to the header
6920 from a latch node. Note that multiple natural loops
6921 may share the same header. */
6922 if (latch != ENTRY_BLOCK_PTR
6923 && TEST_BIT (dom[latch->index], header->index))
6927 loop = loops->array + num_loops;
6929 loop->header = header;
6930 loop->latch = latch;
6932 /* Keep track of blocks that are loop headers so
6933 that we can tell which loops should be merged. */
6934 if (TEST_BIT (headers, header->index))
6935 SET_BIT (loops->shared_headers, header->index);
6936 SET_BIT (headers, header->index);
6938 /* Find nodes contained within the loop. */
6939 loop->nodes = sbitmap_alloc (n_basic_blocks);
6941 = flow_loop_nodes_find (header, latch, loop->nodes);
6943 /* Find edges which exit the loop. Note that a node
6944 may have several exit edges. */
6946 = flow_loop_exits_find (loop->nodes, &loop->exits);
6948 /* Look to see if the loop has a pre-header node. */
6950 = flow_loop_pre_header_find (header, dom);
6957 /* Natural loops with shared headers may either be disjoint or
6958 nested. Disjoint loops with shared headers cannot be inner
6959 loops and should be merged. For now just mark loops that share
6961 for (i = 0; i < num_loops; i++)
6962 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
6963 loops->array[i].shared = 1;
6965 sbitmap_free (headers);
6968 loops->num = num_loops;
6970 /* Save CFG derived information to avoid recomputing it. */
6971 loops->cfg.dom = dom;
6972 loops->cfg.dfs_order = dfs_order;
6974 /* Build the loop hierarchy tree. */
6975 flow_loops_tree_build (loops);
6977 /* Assign the loop nesting depth and enclosed loop level for each
6979 flow_loops_level_compute (loops);
6985 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
6987 flow_loop_outside_edge_p (loop, e)
6988 const struct loop *loop;
6991 if (e->dest != loop->header)
6993 return (e->src == ENTRY_BLOCK_PTR)
6994 || ! TEST_BIT (loop->nodes, e->src->index);