1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
136 #include "insn-flags.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 /* The contents of the current function definition are allocated
172 in this obstack, and all are freed at the end of the function.
173 For top-level functions, this is temporary_obstack.
174 Separate obstacks are made for nested functions. */
176 extern struct obstack *function_obstack;
178 /* Number of basic blocks in the current function. */
182 /* Number of edges in the current function. */
186 /* The basic block array. */
188 varray_type basic_block_info;
190 /* The special entry and exit blocks. */
192 struct basic_block_def entry_exit_blocks[2]
197 NULL, /* local_set */
198 NULL, /* global_live_at_start */
199 NULL, /* global_live_at_end */
201 ENTRY_BLOCK, /* index */
203 -1, -1, /* eh_beg, eh_end */
211 NULL, /* local_set */
212 NULL, /* global_live_at_start */
213 NULL, /* global_live_at_end */
215 EXIT_BLOCK, /* index */
217 -1, -1, /* eh_beg, eh_end */
222 /* Nonzero if the second flow pass has completed. */
225 /* Maximum register number used in this function, plus one. */
229 /* Indexed by n, giving various register information */
231 varray_type reg_n_info;
233 /* Size of a regset for the current function,
234 in (1) bytes and (2) elements. */
239 /* Regset of regs live when calls to `setjmp'-like functions happen. */
240 /* ??? Does this exist only for the setjmp-clobbered warning message? */
242 regset regs_live_at_setjmp;
244 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
245 that have to go in the same hard reg.
246 The first two regs in the list are a pair, and the next two
247 are another pair, etc. */
250 /* Set of registers that may be eliminable. These are handled specially
251 in updating regs_ever_live. */
253 static HARD_REG_SET elim_reg_set;
255 /* The basic block structure for every insn, indexed by uid. */
257 varray_type basic_block_for_insn;
259 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
260 /* ??? Should probably be using LABEL_NUSES instead. It would take a
261 bit of surgery to be able to use or co-opt the routines in jump. */
263 static rtx label_value_list;
264 static rtx tail_recursion_label_list;
266 /* Holds information for tracking conditional register life information. */
267 struct reg_cond_life_info
269 /* An EXPR_LIST of conditions under which a register is dead. */
272 /* ??? Could store mask of bytes that are dead, so that we could finally
273 track lifetimes of multi-word registers accessed via subregs. */
276 /* For use in communicating between propagate_block and its subroutines.
277 Holds all information needed to compute life and def-use information. */
279 struct propagate_block_info
281 /* The basic block we're considering. */
284 /* Bit N is set if register N is conditionally or unconditionally live. */
287 /* Bit N is set if register N is set this insn. */
290 /* Element N is the next insn that uses (hard or pseudo) register N
291 within the current basic block; or zero, if there is no such insn. */
294 /* Contains a list of all the MEMs we are tracking for dead store
298 /* If non-null, record the set of registers set in the basic block. */
301 #ifdef HAVE_conditional_execution
302 /* Indexed by register number, holds a reg_cond_life_info for each
303 register that is not unconditionally live or dead. */
304 splay_tree reg_cond_dead;
306 /* Bit N is set if register N is in an expression in reg_cond_dead. */
310 /* Non-zero if the value of CC0 is live. */
313 /* Flags controling the set of information propagate_block collects. */
317 /* Store the data structures necessary for depth-first search. */
318 struct depth_first_search_dsS {
319 /* stack for backtracking during the algorithm */
322 /* number of edges in the stack. That is, positions 0, ..., sp-1
326 /* record of basic blocks already seen by depth-first search */
327 sbitmap visited_blocks;
329 typedef struct depth_first_search_dsS *depth_first_search_ds;
331 /* Forward declarations */
332 static int count_basic_blocks PARAMS ((rtx));
333 static void find_basic_blocks_1 PARAMS ((rtx));
334 static rtx find_label_refs PARAMS ((rtx, rtx));
335 static void clear_edges PARAMS ((void));
336 static void make_edges PARAMS ((rtx));
337 static void make_label_edge PARAMS ((sbitmap *, basic_block,
339 static void make_eh_edge PARAMS ((sbitmap *, eh_nesting_info *,
340 basic_block, rtx, int));
341 static void mark_critical_edges PARAMS ((void));
342 static void move_stray_eh_region_notes PARAMS ((void));
343 static void record_active_eh_regions PARAMS ((rtx));
345 static void commit_one_edge_insertion PARAMS ((edge));
347 static void delete_unreachable_blocks PARAMS ((void));
348 static void delete_eh_regions PARAMS ((void));
349 static int can_delete_note_p PARAMS ((rtx));
350 static void expunge_block PARAMS ((basic_block));
351 static int can_delete_label_p PARAMS ((rtx));
352 static int tail_recursion_label_p PARAMS ((rtx));
353 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
355 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
357 static int merge_blocks PARAMS ((edge,basic_block,basic_block));
358 static void try_merge_blocks PARAMS ((void));
359 static void tidy_fallthru_edges PARAMS ((void));
360 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
361 static void verify_wide_reg PARAMS ((int, rtx, rtx));
362 static void verify_local_live_at_start PARAMS ((regset, basic_block));
363 static int set_noop_p PARAMS ((rtx));
364 static int noop_move_p PARAMS ((rtx));
365 static void delete_noop_moves PARAMS ((rtx));
366 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
367 static void notice_stack_pointer_modification PARAMS ((rtx));
368 static void mark_reg PARAMS ((rtx, void *));
369 static void mark_regs_live_at_end PARAMS ((regset));
370 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
371 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
372 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
373 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
374 static int insn_dead_p PARAMS ((struct propagate_block_info *,
376 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
378 static void mark_set_regs PARAMS ((struct propagate_block_info *,
380 static void mark_set_1 PARAMS ((struct propagate_block_info *,
381 enum rtx_code, rtx, rtx,
383 #ifdef HAVE_conditional_execution
384 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
386 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
387 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
388 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
390 static rtx ior_reg_cond PARAMS ((rtx, rtx));
391 static rtx not_reg_cond PARAMS ((rtx));
392 static rtx nand_reg_cond PARAMS ((rtx, rtx));
395 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
396 rtx, rtx, rtx, rtx, rtx));
397 static void find_auto_inc PARAMS ((struct propagate_block_info *,
399 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
401 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
403 static void mark_used_reg PARAMS ((struct propagate_block_info *,
405 static void mark_used_regs PARAMS ((struct propagate_block_info *,
407 void dump_flow_info PARAMS ((FILE *));
408 void debug_flow_info PARAMS ((void));
409 static void dump_edge_info PARAMS ((FILE *, edge, int));
411 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
413 static void remove_fake_successors PARAMS ((basic_block));
414 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
416 static void flow_edge_list_print PARAMS ((const char *, const edge *,
418 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
420 static int flow_loop_nested_p PARAMS ((struct loop *,
422 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
424 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
425 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
426 static int flow_depth_first_order_compute PARAMS ((int *, int *));
427 static void flow_dfs_compute_reverse_init
428 PARAMS ((depth_first_search_ds));
429 static void flow_dfs_compute_reverse_add_bb
430 PARAMS ((depth_first_search_ds, basic_block));
431 static basic_block flow_dfs_compute_reverse_execute
432 PARAMS ((depth_first_search_ds));
433 static void flow_dfs_compute_reverse_finish
434 PARAMS ((depth_first_search_ds));
435 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
436 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
438 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
439 static void flow_loops_tree_build PARAMS ((struct loops *));
440 static int flow_loop_level_compute PARAMS ((struct loop *, int));
441 static int flow_loops_level_compute PARAMS ((struct loops *));
443 /* Find basic blocks of the current function.
444 F is the first insn of the function and NREGS the number of register
448 find_basic_blocks (f, nregs, file)
450 int nregs ATTRIBUTE_UNUSED;
451 FILE *file ATTRIBUTE_UNUSED;
455 /* Flush out existing data. */
456 if (basic_block_info != NULL)
462 /* Clear bb->aux on all extant basic blocks. We'll use this as a
463 tag for reuse during create_basic_block, just in case some pass
464 copies around basic block notes improperly. */
465 for (i = 0; i < n_basic_blocks; ++i)
466 BASIC_BLOCK (i)->aux = NULL;
468 VARRAY_FREE (basic_block_info);
471 n_basic_blocks = count_basic_blocks (f);
473 /* Size the basic block table. The actual structures will be allocated
474 by find_basic_blocks_1, since we want to keep the structure pointers
475 stable across calls to find_basic_blocks. */
476 /* ??? This whole issue would be much simpler if we called find_basic_blocks
477 exactly once, and thereafter we don't have a single long chain of
478 instructions at all until close to the end of compilation when we
479 actually lay them out. */
481 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
483 find_basic_blocks_1 (f);
485 /* Record the block to which an insn belongs. */
486 /* ??? This should be done another way, by which (perhaps) a label is
487 tagged directly with the basic block that it starts. It is used for
488 more than that currently, but IMO that is the only valid use. */
490 max_uid = get_max_uid ();
492 /* Leave space for insns life_analysis makes in some cases for auto-inc.
493 These cases are rare, so we don't need too much space. */
494 max_uid += max_uid / 10;
497 compute_bb_for_insn (max_uid);
499 /* Discover the edges of our cfg. */
500 record_active_eh_regions (f);
501 make_edges (label_value_list);
503 /* Do very simple cleanup now, for the benefit of code that runs between
504 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
505 tidy_fallthru_edges ();
507 mark_critical_edges ();
509 #ifdef ENABLE_CHECKING
514 /* Count the basic blocks of the function. */
517 count_basic_blocks (f)
521 register RTX_CODE prev_code;
522 register int count = 0;
524 int call_had_abnormal_edge = 0;
526 prev_code = JUMP_INSN;
527 for (insn = f; insn; insn = NEXT_INSN (insn))
529 register RTX_CODE code = GET_CODE (insn);
531 if (code == CODE_LABEL
532 || (GET_RTX_CLASS (code) == 'i'
533 && (prev_code == JUMP_INSN
534 || prev_code == BARRIER
535 || (prev_code == CALL_INSN && call_had_abnormal_edge))))
538 /* Record whether this call created an edge. */
539 if (code == CALL_INSN)
541 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
542 int region = (note ? INTVAL (XEXP (note, 0)) : 1);
544 call_had_abnormal_edge = 0;
546 /* If there is an EH region or rethrow, we have an edge. */
547 if ((eh_region && region > 0)
548 || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
549 call_had_abnormal_edge = 1;
550 else if (nonlocal_goto_handler_labels && region >= 0)
551 /* If there is a nonlocal goto label and the specified
552 region number isn't -1, we have an edge. (0 means
553 no throw, but might have a nonlocal goto). */
554 call_had_abnormal_edge = 1;
559 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
561 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
565 /* The rest of the compiler works a bit smoother when we don't have to
566 check for the edge case of do-nothing functions with no basic blocks. */
569 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
576 /* Scan a list of insns for labels referred to other than by jumps.
577 This is used to scan the alternatives of a call placeholder. */
579 find_label_refs (f, lvl)
585 for (insn = f; insn; insn = NEXT_INSN (insn))
590 /* Make a list of all labels referred to other than by jumps
591 (which just don't have the REG_LABEL notes).
593 Make a special exception for labels followed by an ADDR*VEC,
594 as this would be a part of the tablejump setup code.
596 Make a special exception for the eh_return_stub_label, which
597 we know isn't part of any otherwise visible control flow. */
599 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
600 if (REG_NOTE_KIND (note) == REG_LABEL)
602 rtx lab = XEXP (note, 0), next;
604 if (lab == eh_return_stub_label)
606 else if ((next = next_nonnote_insn (lab)) != NULL
607 && GET_CODE (next) == JUMP_INSN
608 && (GET_CODE (PATTERN (next)) == ADDR_VEC
609 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
611 else if (GET_CODE (lab) == NOTE)
614 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
621 /* Find all basic blocks of the function whose first insn is F.
623 Collect and return a list of labels whose addresses are taken. This
624 will be used in make_edges for use with computed gotos. */
627 find_basic_blocks_1 (f)
630 register rtx insn, next;
632 rtx bb_note = NULL_RTX;
633 rtx eh_list = NULL_RTX;
639 /* We process the instructions in a slightly different way than we did
640 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
641 closed out the previous block, so that it gets attached at the proper
642 place. Since this form should be equivalent to the previous,
643 count_basic_blocks continues to use the old form as a check. */
645 for (insn = f; insn; insn = next)
647 enum rtx_code code = GET_CODE (insn);
649 next = NEXT_INSN (insn);
655 int kind = NOTE_LINE_NUMBER (insn);
657 /* Keep a LIFO list of the currently active exception notes. */
658 if (kind == NOTE_INSN_EH_REGION_BEG)
659 eh_list = alloc_INSN_LIST (insn, eh_list);
660 else if (kind == NOTE_INSN_EH_REGION_END)
664 eh_list = XEXP (eh_list, 1);
665 free_INSN_LIST_node (t);
668 /* Look for basic block notes with which to keep the
669 basic_block_info pointers stable. Unthread the note now;
670 we'll put it back at the right place in create_basic_block.
671 Or not at all if we've already found a note in this block. */
672 else if (kind == NOTE_INSN_BASIC_BLOCK)
674 if (bb_note == NULL_RTX)
677 next = flow_delete_insn (insn);
683 /* A basic block starts at a label. If we've closed one off due
684 to a barrier or some such, no need to do it again. */
685 if (head != NULL_RTX)
687 /* While we now have edge lists with which other portions of
688 the compiler might determine a call ending a basic block
689 does not imply an abnormal edge, it will be a bit before
690 everything can be updated. So continue to emit a noop at
691 the end of such a block. */
692 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
694 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
695 end = emit_insn_after (nop, end);
698 create_basic_block (i++, head, end, bb_note);
706 /* A basic block ends at a jump. */
707 if (head == NULL_RTX)
711 /* ??? Make a special check for table jumps. The way this
712 happens is truly and amazingly gross. We are about to
713 create a basic block that contains just a code label and
714 an addr*vec jump insn. Worse, an addr_diff_vec creates
715 its own natural loop.
717 Prevent this bit of brain damage, pasting things together
718 correctly in make_edges.
720 The correct solution involves emitting the table directly
721 on the tablejump instruction as a note, or JUMP_LABEL. */
723 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
724 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
732 goto new_bb_inclusive;
735 /* A basic block ends at a barrier. It may be that an unconditional
736 jump already closed the basic block -- no need to do it again. */
737 if (head == NULL_RTX)
740 /* While we now have edge lists with which other portions of the
741 compiler might determine a call ending a basic block does not
742 imply an abnormal edge, it will be a bit before everything can
743 be updated. So continue to emit a noop at the end of such a
745 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
747 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
748 end = emit_insn_after (nop, end);
750 goto new_bb_exclusive;
754 /* Record whether this call created an edge. */
755 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
756 int region = (note ? INTVAL (XEXP (note, 0)) : 1);
757 int call_has_abnormal_edge = 0;
759 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
761 /* Scan each of the alternatives for label refs. */
762 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
763 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
764 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
765 /* Record its tail recursion label, if any. */
766 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
767 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
770 /* If there is an EH region or rethrow, we have an edge. */
771 if ((eh_list && region > 0)
772 || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
773 call_has_abnormal_edge = 1;
774 else if (nonlocal_goto_handler_labels && region >= 0)
775 /* If there is a nonlocal goto label and the specified
776 region number isn't -1, we have an edge. (0 means
777 no throw, but might have a nonlocal goto). */
778 call_has_abnormal_edge = 1;
780 /* A basic block ends at a call that can either throw or
781 do a non-local goto. */
782 if (call_has_abnormal_edge)
785 if (head == NULL_RTX)
790 create_basic_block (i++, head, end, bb_note);
791 head = end = NULL_RTX;
799 if (GET_RTX_CLASS (code) == 'i')
801 if (head == NULL_RTX)
808 if (GET_RTX_CLASS (code) == 'i')
812 /* Make a list of all labels referred to other than by jumps
813 (which just don't have the REG_LABEL notes).
815 Make a special exception for labels followed by an ADDR*VEC,
816 as this would be a part of the tablejump setup code.
818 Make a special exception for the eh_return_stub_label, which
819 we know isn't part of any otherwise visible control flow. */
821 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
822 if (REG_NOTE_KIND (note) == REG_LABEL)
824 rtx lab = XEXP (note, 0), next;
826 if (lab == eh_return_stub_label)
828 else if ((next = next_nonnote_insn (lab)) != NULL
829 && GET_CODE (next) == JUMP_INSN
830 && (GET_CODE (PATTERN (next)) == ADDR_VEC
831 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
833 else if (GET_CODE (lab) == NOTE)
836 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
841 if (head != NULL_RTX)
842 create_basic_block (i++, head, end, bb_note);
844 flow_delete_insn (bb_note);
846 if (i != n_basic_blocks)
849 label_value_list = lvl;
850 tail_recursion_label_list = trll;
853 /* Tidy the CFG by deleting unreachable code and whatnot. */
859 delete_unreachable_blocks ();
860 move_stray_eh_region_notes ();
861 record_active_eh_regions (f);
863 mark_critical_edges ();
865 /* Kill the data we won't maintain. */
866 free_EXPR_LIST_list (&label_value_list);
867 free_EXPR_LIST_list (&tail_recursion_label_list);
870 /* Create a new basic block consisting of the instructions between
871 HEAD and END inclusive. Reuses the note and basic block struct
872 in BB_NOTE, if any. */
875 create_basic_block (index, head, end, bb_note)
877 rtx head, end, bb_note;
882 && ! RTX_INTEGRATED_P (bb_note)
883 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
886 /* If we found an existing note, thread it back onto the chain. */
890 if (GET_CODE (head) == CODE_LABEL)
894 after = PREV_INSN (head);
898 if (after != bb_note && NEXT_INSN (after) != bb_note)
899 reorder_insns (bb_note, bb_note, after);
903 /* Otherwise we must create a note and a basic block structure.
904 Since we allow basic block structs in rtl, give the struct
905 the same lifetime by allocating it off the function obstack
906 rather than using malloc. */
908 bb = (basic_block) obstack_alloc (function_obstack, sizeof (*bb));
909 memset (bb, 0, sizeof (*bb));
911 if (GET_CODE (head) == CODE_LABEL)
912 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
915 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
918 NOTE_BASIC_BLOCK (bb_note) = bb;
921 /* Always include the bb note in the block. */
922 if (NEXT_INSN (end) == bb_note)
928 BASIC_BLOCK (index) = bb;
930 /* Tag the block so that we know it has been used when considering
931 other basic block notes. */
935 /* Records the basic block struct in BB_FOR_INSN, for every instruction
936 indexed by INSN_UID. MAX is the size of the array. */
939 compute_bb_for_insn (max)
944 if (basic_block_for_insn)
945 VARRAY_FREE (basic_block_for_insn);
946 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
948 for (i = 0; i < n_basic_blocks; ++i)
950 basic_block bb = BASIC_BLOCK (i);
957 int uid = INSN_UID (insn);
959 VARRAY_BB (basic_block_for_insn, uid) = bb;
962 insn = NEXT_INSN (insn);
967 /* Free the memory associated with the edge structures. */
975 for (i = 0; i < n_basic_blocks; ++i)
977 basic_block bb = BASIC_BLOCK (i);
979 for (e = bb->succ; e; e = n)
989 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
995 ENTRY_BLOCK_PTR->succ = 0;
996 EXIT_BLOCK_PTR->pred = 0;
1001 /* Identify the edges between basic blocks.
1003 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1004 that are otherwise unreachable may be reachable with a non-local goto.
1006 BB_EH_END is an array indexed by basic block number in which we record
1007 the list of exception regions active at the end of the basic block. */
1010 make_edges (label_value_list)
1011 rtx label_value_list;
1014 eh_nesting_info *eh_nest_info = init_eh_nesting_info ();
1015 sbitmap *edge_cache = NULL;
1017 /* Assume no computed jump; revise as we create edges. */
1018 current_function_has_computed_jump = 0;
1020 /* Heavy use of computed goto in machine-generated code can lead to
1021 nearly fully-connected CFGs. In that case we spend a significant
1022 amount of time searching the edge lists for duplicates. */
1023 if (forced_labels || label_value_list)
1025 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1026 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1029 /* By nature of the way these get numbered, block 0 is always the entry. */
1030 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1032 for (i = 0; i < n_basic_blocks; ++i)
1034 basic_block bb = BASIC_BLOCK (i);
1037 int force_fallthru = 0;
1039 /* Examine the last instruction of the block, and discover the
1040 ways we can leave the block. */
1043 code = GET_CODE (insn);
1046 if (code == JUMP_INSN)
1050 /* ??? Recognize a tablejump and do the right thing. */
1051 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1052 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1053 && GET_CODE (tmp) == JUMP_INSN
1054 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1055 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1060 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1061 vec = XVEC (PATTERN (tmp), 0);
1063 vec = XVEC (PATTERN (tmp), 1);
1065 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1066 make_label_edge (edge_cache, bb,
1067 XEXP (RTVEC_ELT (vec, j), 0), 0);
1069 /* Some targets (eg, ARM) emit a conditional jump that also
1070 contains the out-of-range target. Scan for these and
1071 add an edge if necessary. */
1072 if ((tmp = single_set (insn)) != NULL
1073 && SET_DEST (tmp) == pc_rtx
1074 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1075 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1076 make_label_edge (edge_cache, bb,
1077 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1079 #ifdef CASE_DROPS_THROUGH
1080 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1081 us naturally detecting fallthru into the next block. */
1086 /* If this is a computed jump, then mark it as reaching
1087 everything on the label_value_list and forced_labels list. */
1088 else if (computed_jump_p (insn))
1090 current_function_has_computed_jump = 1;
1092 for (x = label_value_list; x; x = XEXP (x, 1))
1093 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1095 for (x = forced_labels; x; x = XEXP (x, 1))
1096 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1099 /* Returns create an exit out. */
1100 else if (returnjump_p (insn))
1101 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1103 /* Otherwise, we have a plain conditional or unconditional jump. */
1106 if (! JUMP_LABEL (insn))
1108 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1112 /* If this is a sibling call insn, then this is in effect a
1113 combined call and return, and so we need an edge to the
1114 exit block. No need to worry about EH edges, since we
1115 wouldn't have created the sibling call in the first place. */
1117 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1118 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1119 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1122 /* If this is a CALL_INSN, then mark it as reaching the active EH
1123 handler for this CALL_INSN. If we're handling asynchronous
1124 exceptions then any insn can reach any of the active handlers.
1126 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1128 if (code == CALL_INSN || asynchronous_exceptions)
1130 /* Add any appropriate EH edges. We do this unconditionally
1131 since there may be a REG_EH_REGION or REG_EH_RETHROW note
1132 on the call, and this needn't be within an EH region. */
1133 make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end);
1135 /* If we have asynchronous exceptions, do the same for *all*
1136 exception regions active in the block. */
1137 if (asynchronous_exceptions
1138 && bb->eh_beg != bb->eh_end)
1140 if (bb->eh_beg >= 0)
1141 make_eh_edge (edge_cache, eh_nest_info, bb,
1142 NULL_RTX, bb->eh_beg);
1144 for (x = bb->head; x != bb->end; x = NEXT_INSN (x))
1145 if (GET_CODE (x) == NOTE
1146 && (NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_BEG
1147 || NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_END))
1149 int region = NOTE_EH_HANDLER (x);
1150 make_eh_edge (edge_cache, eh_nest_info, bb,
1155 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1157 /* ??? This could be made smarter: in some cases it's possible
1158 to tell that certain calls will not do a nonlocal goto.
1160 For example, if the nested functions that do the nonlocal
1161 gotos do not have their addresses taken, then only calls to
1162 those functions or to other nested functions that use them
1163 could possibly do nonlocal gotos. */
1164 /* We do know that a REG_EH_REGION note with a value less
1165 than 0 is guaranteed not to perform a non-local goto. */
1166 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1167 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1168 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1169 make_label_edge (edge_cache, bb, XEXP (x, 0),
1170 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1174 /* We know something about the structure of the function __throw in
1175 libgcc2.c. It is the only function that ever contains eh_stub
1176 labels. It modifies its return address so that the last block
1177 returns to one of the eh_stub labels within it. So we have to
1178 make additional edges in the flow graph. */
1179 if (i + 1 == n_basic_blocks && eh_return_stub_label != 0)
1180 make_label_edge (edge_cache, bb, eh_return_stub_label, EDGE_EH);
1182 /* Find out if we can drop through to the next block. */
1183 insn = next_nonnote_insn (insn);
1184 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1185 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1186 else if (i + 1 < n_basic_blocks)
1188 rtx tmp = BLOCK_HEAD (i + 1);
1189 if (GET_CODE (tmp) == NOTE)
1190 tmp = next_nonnote_insn (tmp);
1191 if (force_fallthru || insn == tmp)
1192 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1196 free_eh_nesting_info (eh_nest_info);
1198 sbitmap_vector_free (edge_cache);
1201 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1202 about the edge that is accumulated between calls. */
1205 make_edge (edge_cache, src, dst, flags)
1206 sbitmap *edge_cache;
1207 basic_block src, dst;
1213 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1214 many edges to them, and we didn't allocate memory for it. */
1215 use_edge_cache = (edge_cache
1216 && src != ENTRY_BLOCK_PTR
1217 && dst != EXIT_BLOCK_PTR);
1219 /* Make sure we don't add duplicate edges. */
1220 if (! use_edge_cache || TEST_BIT (edge_cache[src->index], dst->index))
1221 for (e = src->succ; e; e = e->succ_next)
1228 e = (edge) xcalloc (1, sizeof (*e));
1231 e->succ_next = src->succ;
1232 e->pred_next = dst->pred;
1241 SET_BIT (edge_cache[src->index], dst->index);
1244 /* Create an edge from a basic block to a label. */
1247 make_label_edge (edge_cache, src, label, flags)
1248 sbitmap *edge_cache;
1253 if (GET_CODE (label) != CODE_LABEL)
1256 /* If the label was never emitted, this insn is junk, but avoid a
1257 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1258 as a result of a syntax error and a diagnostic has already been
1261 if (INSN_UID (label) == 0)
1264 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1267 /* Create the edges generated by INSN in REGION. */
1270 make_eh_edge (edge_cache, eh_nest_info, src, insn, region)
1271 sbitmap *edge_cache;
1272 eh_nesting_info *eh_nest_info;
1277 handler_info **handler_list;
1280 is_call = (insn && GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1281 num = reachable_handlers (region, eh_nest_info, insn, &handler_list);
1284 make_label_edge (edge_cache, src, handler_list[num]->handler_label,
1285 EDGE_ABNORMAL | EDGE_EH | is_call);
1289 /* EH_REGION notes appearing between basic blocks is ambiguous, and even
1290 dangerous if we intend to move basic blocks around. Move such notes
1291 into the following block. */
1294 move_stray_eh_region_notes ()
1299 if (n_basic_blocks < 2)
1302 b2 = BASIC_BLOCK (n_basic_blocks - 1);
1303 for (i = n_basic_blocks - 2; i >= 0; --i, b2 = b1)
1305 rtx insn, next, list = NULL_RTX;
1307 b1 = BASIC_BLOCK (i);
1308 for (insn = NEXT_INSN (b1->end); insn != b2->head; insn = next)
1310 next = NEXT_INSN (insn);
1311 if (GET_CODE (insn) == NOTE
1312 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1313 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1315 /* Unlink from the insn chain. */
1316 NEXT_INSN (PREV_INSN (insn)) = next;
1317 PREV_INSN (next) = PREV_INSN (insn);
1320 NEXT_INSN (insn) = list;
1325 if (list == NULL_RTX)
1328 /* Find where to insert these things. */
1330 if (GET_CODE (insn) == CODE_LABEL)
1331 insn = NEXT_INSN (insn);
1335 next = NEXT_INSN (list);
1336 add_insn_after (list, insn);
1342 /* Recompute eh_beg/eh_end for each basic block. */
1345 record_active_eh_regions (f)
1348 rtx insn, eh_list = NULL_RTX;
1350 basic_block bb = BASIC_BLOCK (0);
1352 for (insn = f; insn; insn = NEXT_INSN (insn))
1354 if (bb->head == insn)
1355 bb->eh_beg = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1357 if (GET_CODE (insn) == NOTE)
1359 int kind = NOTE_LINE_NUMBER (insn);
1360 if (kind == NOTE_INSN_EH_REGION_BEG)
1361 eh_list = alloc_INSN_LIST (insn, eh_list);
1362 else if (kind == NOTE_INSN_EH_REGION_END)
1364 rtx t = XEXP (eh_list, 1);
1365 free_INSN_LIST_node (eh_list);
1370 if (bb->end == insn)
1372 bb->eh_end = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1374 if (i == n_basic_blocks)
1376 bb = BASIC_BLOCK (i);
1381 /* Identify critical edges and set the bits appropriately. */
1384 mark_critical_edges ()
1386 int i, n = n_basic_blocks;
1389 /* We begin with the entry block. This is not terribly important now,
1390 but could be if a front end (Fortran) implemented alternate entry
1392 bb = ENTRY_BLOCK_PTR;
1399 /* (1) Critical edges must have a source with multiple successors. */
1400 if (bb->succ && bb->succ->succ_next)
1402 for (e = bb->succ; e; e = e->succ_next)
1404 /* (2) Critical edges must have a destination with multiple
1405 predecessors. Note that we know there is at least one
1406 predecessor -- the edge we followed to get here. */
1407 if (e->dest->pred->pred_next)
1408 e->flags |= EDGE_CRITICAL;
1410 e->flags &= ~EDGE_CRITICAL;
1415 for (e = bb->succ; e; e = e->succ_next)
1416 e->flags &= ~EDGE_CRITICAL;
1421 bb = BASIC_BLOCK (i);
1425 /* Split a block BB after insn INSN creating a new fallthru edge.
1426 Return the new edge. Note that to keep other parts of the compiler happy,
1427 this function renumbers all the basic blocks so that the new
1428 one has a number one greater than the block split. */
1431 split_block (bb, insn)
1441 /* There is no point splitting the block after its end. */
1442 if (bb->end == insn)
1445 /* Create the new structures. */
1446 new_bb = (basic_block) obstack_alloc (function_obstack, sizeof (*new_bb));
1447 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1450 memset (new_bb, 0, sizeof (*new_bb));
1452 new_bb->head = NEXT_INSN (insn);
1453 new_bb->end = bb->end;
1456 new_bb->succ = bb->succ;
1457 bb->succ = new_edge;
1458 new_bb->pred = new_edge;
1459 new_bb->count = bb->count;
1460 new_bb->loop_depth = bb->loop_depth;
1463 new_edge->dest = new_bb;
1464 new_edge->flags = EDGE_FALLTHRU;
1465 new_edge->probability = REG_BR_PROB_BASE;
1466 new_edge->count = bb->count;
1468 /* Redirect the src of the successor edges of bb to point to new_bb. */
1469 for (e = new_bb->succ; e; e = e->succ_next)
1472 /* Place the new block just after the block being split. */
1473 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1475 /* Some parts of the compiler expect blocks to be number in
1476 sequential order so insert the new block immediately after the
1477 block being split.. */
1479 for (i = n_basic_blocks - 1; i > j + 1; --i)
1481 basic_block tmp = BASIC_BLOCK (i - 1);
1482 BASIC_BLOCK (i) = tmp;
1486 BASIC_BLOCK (i) = new_bb;
1489 /* Create the basic block note. */
1490 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1492 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1493 new_bb->head = bb_note;
1495 update_bb_for_insn (new_bb);
1497 if (bb->global_live_at_start)
1499 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
1500 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
1501 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1503 /* We now have to calculate which registers are live at the end
1504 of the split basic block and at the start of the new basic
1505 block. Start with those registers that are known to be live
1506 at the end of the original basic block and get
1507 propagate_block to determine which registers are live. */
1508 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1509 propagate_block (new_bb, new_bb->global_live_at_start, NULL, 0);
1510 COPY_REG_SET (bb->global_live_at_end,
1511 new_bb->global_live_at_start);
1518 /* Split a (typically critical) edge. Return the new block.
1519 Abort on abnormal edges.
1521 ??? The code generally expects to be called on critical edges.
1522 The case of a block ending in an unconditional jump to a
1523 block with multiple predecessors is not handled optimally. */
1526 split_edge (edge_in)
1529 basic_block old_pred, bb, old_succ;
1534 /* Abnormal edges cannot be split. */
1535 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1538 old_pred = edge_in->src;
1539 old_succ = edge_in->dest;
1541 /* Remove the existing edge from the destination's pred list. */
1544 for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next)
1546 *pp = edge_in->pred_next;
1547 edge_in->pred_next = NULL;
1550 /* Create the new structures. */
1551 bb = (basic_block) obstack_alloc (function_obstack, sizeof (*bb));
1552 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
1555 memset (bb, 0, sizeof (*bb));
1557 /* ??? This info is likely going to be out of date very soon. */
1558 if (old_succ->global_live_at_start)
1560 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
1561 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
1562 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
1563 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
1568 bb->succ = edge_out;
1569 bb->count = edge_in->count;
1572 edge_in->flags &= ~EDGE_CRITICAL;
1574 edge_out->pred_next = old_succ->pred;
1575 edge_out->succ_next = NULL;
1577 edge_out->dest = old_succ;
1578 edge_out->flags = EDGE_FALLTHRU;
1579 edge_out->probability = REG_BR_PROB_BASE;
1580 edge_out->count = edge_in->count;
1582 old_succ->pred = edge_out;
1584 /* Tricky case -- if there existed a fallthru into the successor
1585 (and we're not it) we must add a new unconditional jump around
1586 the new block we're actually interested in.
1588 Further, if that edge is critical, this means a second new basic
1589 block must be created to hold it. In order to simplify correct
1590 insn placement, do this before we touch the existing basic block
1591 ordering for the block we were really wanting. */
1592 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1595 for (e = edge_out->pred_next; e; e = e->pred_next)
1596 if (e->flags & EDGE_FALLTHRU)
1601 basic_block jump_block;
1604 if ((e->flags & EDGE_CRITICAL) == 0
1605 && e->src != ENTRY_BLOCK_PTR)
1607 /* Non critical -- we can simply add a jump to the end
1608 of the existing predecessor. */
1609 jump_block = e->src;
1613 /* We need a new block to hold the jump. The simplest
1614 way to do the bulk of the work here is to recursively
1616 jump_block = split_edge (e);
1617 e = jump_block->succ;
1620 /* Now add the jump insn ... */
1621 pos = emit_jump_insn_after (gen_jump (old_succ->head),
1623 jump_block->end = pos;
1624 if (basic_block_for_insn)
1625 set_block_for_insn (pos, jump_block);
1626 emit_barrier_after (pos);
1628 /* ... let jump know that label is in use, ... */
1629 JUMP_LABEL (pos) = old_succ->head;
1630 ++LABEL_NUSES (old_succ->head);
1632 /* ... and clear fallthru on the outgoing edge. */
1633 e->flags &= ~EDGE_FALLTHRU;
1635 /* Continue splitting the interesting edge. */
1639 /* Place the new block just in front of the successor. */
1640 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1641 if (old_succ == EXIT_BLOCK_PTR)
1642 j = n_basic_blocks - 1;
1644 j = old_succ->index;
1645 for (i = n_basic_blocks - 1; i > j; --i)
1647 basic_block tmp = BASIC_BLOCK (i - 1);
1648 BASIC_BLOCK (i) = tmp;
1651 BASIC_BLOCK (i) = bb;
1654 /* Create the basic block note.
1656 Where we place the note can have a noticable impact on the generated
1657 code. Consider this cfg:
1667 If we need to insert an insn on the edge from block 0 to block 1,
1668 we want to ensure the instructions we insert are outside of any
1669 loop notes that physically sit between block 0 and block 1. Otherwise
1670 we confuse the loop optimizer into thinking the loop is a phony. */
1671 if (old_succ != EXIT_BLOCK_PTR
1672 && PREV_INSN (old_succ->head)
1673 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
1674 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
1675 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1676 PREV_INSN (old_succ->head));
1677 else if (old_succ != EXIT_BLOCK_PTR)
1678 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
1680 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
1681 NOTE_BASIC_BLOCK (bb_note) = bb;
1682 bb->head = bb->end = bb_note;
1684 /* Not quite simple -- for non-fallthru edges, we must adjust the
1685 predecessor's jump instruction to target our new block. */
1686 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1688 rtx tmp, insn = old_pred->end;
1689 rtx old_label = old_succ->head;
1690 rtx new_label = gen_label_rtx ();
1692 if (GET_CODE (insn) != JUMP_INSN)
1695 /* ??? Recognize a tablejump and adjust all matching cases. */
1696 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1697 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1698 && GET_CODE (tmp) == JUMP_INSN
1699 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1700 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1705 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1706 vec = XVEC (PATTERN (tmp), 0);
1708 vec = XVEC (PATTERN (tmp), 1);
1710 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1711 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1713 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
1714 --LABEL_NUSES (old_label);
1715 ++LABEL_NUSES (new_label);
1718 /* Handle casesi dispatch insns */
1719 if ((tmp = single_set (insn)) != NULL
1720 && SET_DEST (tmp) == pc_rtx
1721 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1722 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1723 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1725 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1727 --LABEL_NUSES (old_label);
1728 ++LABEL_NUSES (new_label);
1733 /* This would have indicated an abnormal edge. */
1734 if (computed_jump_p (insn))
1737 /* A return instruction can't be redirected. */
1738 if (returnjump_p (insn))
1741 /* If the insn doesn't go where we think, we're confused. */
1742 if (JUMP_LABEL (insn) != old_label)
1745 redirect_jump (insn, new_label, 0);
1748 emit_label_before (new_label, bb_note);
1749 bb->head = new_label;
1755 /* Queue instructions for insertion on an edge between two basic blocks.
1756 The new instructions and basic blocks (if any) will not appear in the
1757 CFG until commit_edge_insertions is called. */
1760 insert_insn_on_edge (pattern, e)
1764 /* We cannot insert instructions on an abnormal critical edge.
1765 It will be easier to find the culprit if we die now. */
1766 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
1767 == (EDGE_ABNORMAL|EDGE_CRITICAL))
1770 if (e->insns == NULL_RTX)
1773 push_to_sequence (e->insns);
1775 emit_insn (pattern);
1777 e->insns = get_insns ();
1781 /* Update the CFG for the instructions queued on edge E. */
1784 commit_one_edge_insertion (e)
1787 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1790 /* Pull the insns off the edge now since the edge might go away. */
1792 e->insns = NULL_RTX;
1794 /* Figure out where to put these things. If the destination has
1795 one predecessor, insert there. Except for the exit block. */
1796 if (e->dest->pred->pred_next == NULL
1797 && e->dest != EXIT_BLOCK_PTR)
1801 /* Get the location correct wrt a code label, and "nice" wrt
1802 a basic block note, and before everything else. */
1804 if (GET_CODE (tmp) == CODE_LABEL)
1805 tmp = NEXT_INSN (tmp);
1806 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1807 tmp = NEXT_INSN (tmp);
1808 if (tmp == bb->head)
1811 after = PREV_INSN (tmp);
1814 /* If the source has one successor and the edge is not abnormal,
1815 insert there. Except for the entry block. */
1816 else if ((e->flags & EDGE_ABNORMAL) == 0
1817 && e->src->succ->succ_next == NULL
1818 && e->src != ENTRY_BLOCK_PTR)
1821 /* It is possible to have a non-simple jump here. Consider a target
1822 where some forms of unconditional jumps clobber a register. This
1823 happens on the fr30 for example.
1825 We know this block has a single successor, so we can just emit
1826 the queued insns before the jump. */
1827 if (GET_CODE (bb->end) == JUMP_INSN)
1833 /* We'd better be fallthru, or we've lost track of what's what. */
1834 if ((e->flags & EDGE_FALLTHRU) == 0)
1841 /* Otherwise we must split the edge. */
1844 bb = split_edge (e);
1848 /* Now that we've found the spot, do the insertion. */
1850 /* Set the new block number for these insns, if structure is allocated. */
1851 if (basic_block_for_insn)
1854 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
1855 set_block_for_insn (i, bb);
1860 emit_insns_before (insns, before);
1861 if (before == bb->head)
1864 last = prev_nonnote_insn (before);
1868 last = emit_insns_after (insns, after);
1869 if (after == bb->end)
1873 if (returnjump_p (last))
1875 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1876 This is not currently a problem because this only happens
1877 for the (single) epilogue, which already has a fallthru edge
1881 if (e->dest != EXIT_BLOCK_PTR
1882 || e->succ_next != NULL
1883 || (e->flags & EDGE_FALLTHRU) == 0)
1885 e->flags &= ~EDGE_FALLTHRU;
1887 emit_barrier_after (last);
1891 flow_delete_insn (before);
1893 else if (GET_CODE (last) == JUMP_INSN)
1897 /* Update the CFG for all queued instructions. */
1900 commit_edge_insertions ()
1905 #ifdef ENABLE_CHECKING
1906 verify_flow_info ();
1910 bb = ENTRY_BLOCK_PTR;
1915 for (e = bb->succ; e; e = next)
1917 next = e->succ_next;
1919 commit_one_edge_insertion (e);
1922 if (++i >= n_basic_blocks)
1924 bb = BASIC_BLOCK (i);
1928 /* Delete all unreachable basic blocks. */
1931 delete_unreachable_blocks ()
1933 basic_block *worklist, *tos;
1934 int deleted_handler;
1939 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
1941 /* Use basic_block->aux as a marker. Clear them all. */
1943 for (i = 0; i < n; ++i)
1944 BASIC_BLOCK (i)->aux = NULL;
1946 /* Add our starting points to the worklist. Almost always there will
1947 be only one. It isn't inconcievable that we might one day directly
1948 support Fortran alternate entry points. */
1950 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1954 /* Mark the block with a handy non-null value. */
1958 /* Iterate: find everything reachable from what we've already seen. */
1960 while (tos != worklist)
1962 basic_block b = *--tos;
1964 for (e = b->succ; e; e = e->succ_next)
1972 /* Delete all unreachable basic blocks. Count down so that we don't
1973 interfere with the block renumbering that happens in flow_delete_block. */
1975 deleted_handler = 0;
1977 for (i = n - 1; i >= 0; --i)
1979 basic_block b = BASIC_BLOCK (i);
1982 /* This block was found. Tidy up the mark. */
1985 deleted_handler |= flow_delete_block (b);
1988 tidy_fallthru_edges ();
1990 /* If we deleted an exception handler, we may have EH region begin/end
1991 blocks to remove as well. */
1992 if (deleted_handler)
1993 delete_eh_regions ();
1998 /* Find EH regions for which there is no longer a handler, and delete them. */
2001 delete_eh_regions ()
2005 update_rethrow_references ();
2007 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2008 if (GET_CODE (insn) == NOTE)
2010 if ((NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2011 || (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2013 int num = NOTE_EH_HANDLER (insn);
2014 /* A NULL handler indicates a region is no longer needed,
2015 as long as its rethrow label isn't used. */
2016 if (get_first_handler (num) == NULL && ! rethrow_used (num))
2018 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2019 NOTE_SOURCE_FILE (insn) = 0;
2025 /* Return true if NOTE is not one of the ones that must be kept paired,
2026 so that we may simply delete them. */
2029 can_delete_note_p (note)
2032 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2033 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2036 /* Unlink a chain of insns between START and FINISH, leaving notes
2037 that must be paired. */
2040 flow_delete_insn_chain (start, finish)
2043 /* Unchain the insns one by one. It would be quicker to delete all
2044 of these with a single unchaining, rather than one at a time, but
2045 we need to keep the NOTE's. */
2051 next = NEXT_INSN (start);
2052 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2054 else if (GET_CODE (start) == CODE_LABEL
2055 && ! can_delete_label_p (start))
2057 const char *name = LABEL_NAME (start);
2058 PUT_CODE (start, NOTE);
2059 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2060 NOTE_SOURCE_FILE (start) = name;
2063 next = flow_delete_insn (start);
2065 if (start == finish)
2071 /* Delete the insns in a (non-live) block. We physically delete every
2072 non-deleted-note insn, and update the flow graph appropriately.
2074 Return nonzero if we deleted an exception handler. */
2076 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2077 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2080 flow_delete_block (b)
2083 int deleted_handler = 0;
2086 /* If the head of this block is a CODE_LABEL, then it might be the
2087 label for an exception handler which can't be reached.
2089 We need to remove the label from the exception_handler_label list
2090 and remove the associated NOTE_INSN_EH_REGION_BEG and
2091 NOTE_INSN_EH_REGION_END notes. */
2095 never_reached_warning (insn);
2097 if (GET_CODE (insn) == CODE_LABEL)
2099 rtx x, *prev = &exception_handler_labels;
2101 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2103 if (XEXP (x, 0) == insn)
2105 /* Found a match, splice this label out of the EH label list. */
2106 *prev = XEXP (x, 1);
2107 XEXP (x, 1) = NULL_RTX;
2108 XEXP (x, 0) = NULL_RTX;
2110 /* Remove the handler from all regions */
2111 remove_handler (insn);
2112 deleted_handler = 1;
2115 prev = &XEXP (x, 1);
2119 /* Include any jump table following the basic block. */
2121 if (GET_CODE (end) == JUMP_INSN
2122 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2123 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2124 && GET_CODE (tmp) == JUMP_INSN
2125 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2126 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2129 /* Include any barrier that may follow the basic block. */
2130 tmp = next_nonnote_insn (end);
2131 if (tmp && GET_CODE (tmp) == BARRIER)
2134 /* Selectively delete the entire chain. */
2135 flow_delete_insn_chain (insn, end);
2137 /* Remove the edges into and out of this block. Note that there may
2138 indeed be edges in, if we are removing an unreachable loop. */
2142 for (e = b->pred; e; e = next)
2144 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2147 next = e->pred_next;
2151 for (e = b->succ; e; e = next)
2153 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2156 next = e->succ_next;
2165 /* Remove the basic block from the array, and compact behind it. */
2168 return deleted_handler;
2171 /* Remove block B from the basic block array and compact behind it. */
2177 int i, n = n_basic_blocks;
2179 for (i = b->index; i + 1 < n; ++i)
2181 basic_block x = BASIC_BLOCK (i + 1);
2182 BASIC_BLOCK (i) = x;
2186 basic_block_info->num_elements--;
2190 /* Delete INSN by patching it out. Return the next insn. */
2193 flow_delete_insn (insn)
2196 rtx prev = PREV_INSN (insn);
2197 rtx next = NEXT_INSN (insn);
2200 PREV_INSN (insn) = NULL_RTX;
2201 NEXT_INSN (insn) = NULL_RTX;
2202 INSN_DELETED_P (insn) = 1;
2205 NEXT_INSN (prev) = next;
2207 PREV_INSN (next) = prev;
2209 set_last_insn (prev);
2211 if (GET_CODE (insn) == CODE_LABEL)
2212 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2214 /* If deleting a jump, decrement the use count of the label. Deleting
2215 the label itself should happen in the normal course of block merging. */
2216 if (GET_CODE (insn) == JUMP_INSN
2217 && JUMP_LABEL (insn)
2218 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2219 LABEL_NUSES (JUMP_LABEL (insn))--;
2221 /* Also if deleting an insn that references a label. */
2222 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2223 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2224 LABEL_NUSES (XEXP (note, 0))--;
2229 /* True if a given label can be deleted. */
2232 can_delete_label_p (label)
2237 if (LABEL_PRESERVE_P (label))
2240 for (x = forced_labels; x; x = XEXP (x, 1))
2241 if (label == XEXP (x, 0))
2243 for (x = label_value_list; x; x = XEXP (x, 1))
2244 if (label == XEXP (x, 0))
2246 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2247 if (label == XEXP (x, 0))
2250 /* User declared labels must be preserved. */
2251 if (LABEL_NAME (label) != 0)
2258 tail_recursion_label_p (label)
2263 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2264 if (label == XEXP (x, 0))
2270 /* Blocks A and B are to be merged into a single block A. The insns
2271 are already contiguous, hence `nomove'. */
2274 merge_blocks_nomove (a, b)
2278 rtx b_head, b_end, a_end;
2279 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2282 /* If there was a CODE_LABEL beginning B, delete it. */
2285 if (GET_CODE (b_head) == CODE_LABEL)
2287 /* Detect basic blocks with nothing but a label. This can happen
2288 in particular at the end of a function. */
2289 if (b_head == b_end)
2291 del_first = del_last = b_head;
2292 b_head = NEXT_INSN (b_head);
2295 /* Delete the basic block note. */
2296 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2298 if (b_head == b_end)
2303 b_head = NEXT_INSN (b_head);
2306 /* If there was a jump out of A, delete it. */
2308 if (GET_CODE (a_end) == JUMP_INSN)
2312 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2313 if (GET_CODE (prev) != NOTE
2314 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2321 /* If this was a conditional jump, we need to also delete
2322 the insn that set cc0. */
2323 if (prev && sets_cc0_p (prev))
2326 prev = prev_nonnote_insn (prev);
2335 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2336 del_first = NEXT_INSN (a_end);
2338 /* Delete everything marked above as well as crap that might be
2339 hanging out between the two blocks. */
2340 flow_delete_insn_chain (del_first, del_last);
2342 /* Normally there should only be one successor of A and that is B, but
2343 partway though the merge of blocks for conditional_execution we'll
2344 be merging a TEST block with THEN and ELSE successors. Free the
2345 whole lot of them and hope the caller knows what they're doing. */
2347 remove_edge (a->succ);
2349 /* Adjust the edges out of B for the new owner. */
2350 for (e = b->succ; e; e = e->succ_next)
2354 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2355 b->pred = b->succ = NULL;
2357 /* Reassociate the insns of B with A. */
2360 if (basic_block_for_insn)
2362 BLOCK_FOR_INSN (b_head) = a;
2363 while (b_head != b_end)
2365 b_head = NEXT_INSN (b_head);
2366 BLOCK_FOR_INSN (b_head) = a;
2376 /* Blocks A and B are to be merged into a single block. A has no incoming
2377 fallthru edge, so it can be moved before B without adding or modifying
2378 any jumps (aside from the jump from A to B). */
2381 merge_blocks_move_predecessor_nojumps (a, b)
2384 rtx start, end, barrier;
2390 barrier = next_nonnote_insn (end);
2391 if (GET_CODE (barrier) != BARRIER)
2393 flow_delete_insn (barrier);
2395 /* Move block and loop notes out of the chain so that we do not
2396 disturb their order.
2398 ??? A better solution would be to squeeze out all the non-nested notes
2399 and adjust the block trees appropriately. Even better would be to have
2400 a tighter connection between block trees and rtl so that this is not
2402 start = squeeze_notes (start, end);
2404 /* Scramble the insn chain. */
2405 if (end != PREV_INSN (b->head))
2406 reorder_insns (start, end, PREV_INSN (b->head));
2410 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2411 a->index, b->index);
2414 /* Swap the records for the two blocks around. Although we are deleting B,
2415 A is now where B was and we want to compact the BB array from where
2417 BASIC_BLOCK (a->index) = b;
2418 BASIC_BLOCK (b->index) = a;
2420 a->index = b->index;
2423 /* Now blocks A and B are contiguous. Merge them. */
2424 merge_blocks_nomove (a, b);
2429 /* Blocks A and B are to be merged into a single block. B has no outgoing
2430 fallthru edge, so it can be moved after A without adding or modifying
2431 any jumps (aside from the jump from A to B). */
2434 merge_blocks_move_successor_nojumps (a, b)
2437 rtx start, end, barrier;
2441 barrier = NEXT_INSN (end);
2443 /* Recognize a jump table following block B. */
2444 if (GET_CODE (barrier) == CODE_LABEL
2445 && NEXT_INSN (barrier)
2446 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2447 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2448 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2450 end = NEXT_INSN (barrier);
2451 barrier = NEXT_INSN (end);
2454 /* There had better have been a barrier there. Delete it. */
2455 if (GET_CODE (barrier) != BARRIER)
2457 flow_delete_insn (barrier);
2459 /* Move block and loop notes out of the chain so that we do not
2460 disturb their order.
2462 ??? A better solution would be to squeeze out all the non-nested notes
2463 and adjust the block trees appropriately. Even better would be to have
2464 a tighter connection between block trees and rtl so that this is not
2466 start = squeeze_notes (start, end);
2468 /* Scramble the insn chain. */
2469 reorder_insns (start, end, a->end);
2471 /* Now blocks A and B are contiguous. Merge them. */
2472 merge_blocks_nomove (a, b);
2476 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2477 b->index, a->index);
2483 /* Attempt to merge basic blocks that are potentially non-adjacent.
2484 Return true iff the attempt succeeded. */
2487 merge_blocks (e, b, c)
2491 /* If C has a tail recursion label, do not merge. There is no
2492 edge recorded from the call_placeholder back to this label, as
2493 that would make optimize_sibling_and_tail_recursive_calls more
2494 complex for no gain. */
2495 if (GET_CODE (c->head) == CODE_LABEL
2496 && tail_recursion_label_p (c->head))
2499 /* If B has a fallthru edge to C, no need to move anything. */
2500 if (e->flags & EDGE_FALLTHRU)
2502 merge_blocks_nomove (b, c);
2506 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2507 b->index, c->index);
2516 int c_has_outgoing_fallthru;
2517 int b_has_incoming_fallthru;
2519 /* We must make sure to not munge nesting of exception regions,
2520 lexical blocks, and loop notes.
2522 The first is taken care of by requiring that the active eh
2523 region at the end of one block always matches the active eh
2524 region at the beginning of the next block.
2526 The later two are taken care of by squeezing out all the notes. */
2528 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2529 executed and we may want to treat blocks which have two out
2530 edges, one normal, one abnormal as only having one edge for
2531 block merging purposes. */
2533 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2534 if (tmp_edge->flags & EDGE_FALLTHRU)
2536 c_has_outgoing_fallthru = (tmp_edge != NULL);
2538 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2539 if (tmp_edge->flags & EDGE_FALLTHRU)
2541 b_has_incoming_fallthru = (tmp_edge != NULL);
2543 /* If B does not have an incoming fallthru, and the exception regions
2544 match, then it can be moved immediately before C without introducing
2547 C can not be the first block, so we do not have to worry about
2548 accessing a non-existent block. */
2549 d = BASIC_BLOCK (c->index - 1);
2550 if (! b_has_incoming_fallthru
2551 && d->eh_end == b->eh_beg
2552 && b->eh_end == c->eh_beg)
2553 return merge_blocks_move_predecessor_nojumps (b, c);
2555 /* Otherwise, we're going to try to move C after B. Make sure the
2556 exception regions match.
2558 If B is the last basic block, then we must not try to access the
2559 block structure for block B + 1. Luckily in that case we do not
2560 need to worry about matching exception regions. */
2561 d = (b->index + 1 < n_basic_blocks ? BASIC_BLOCK (b->index + 1) : NULL);
2562 if (b->eh_end == c->eh_beg
2563 && (d == NULL || c->eh_end == d->eh_beg))
2565 /* If C does not have an outgoing fallthru, then it can be moved
2566 immediately after B without introducing or modifying jumps. */
2567 if (! c_has_outgoing_fallthru)
2568 return merge_blocks_move_successor_nojumps (b, c);
2570 /* Otherwise, we'll need to insert an extra jump, and possibly
2571 a new block to contain it. */
2572 /* ??? Not implemented yet. */
2579 /* Top level driver for merge_blocks. */
2586 /* Attempt to merge blocks as made possible by edge removal. If a block
2587 has only one successor, and the successor has only one predecessor,
2588 they may be combined. */
2590 for (i = 0; i < n_basic_blocks;)
2592 basic_block c, b = BASIC_BLOCK (i);
2595 /* A loop because chains of blocks might be combineable. */
2596 while ((s = b->succ) != NULL
2597 && s->succ_next == NULL
2598 && (s->flags & EDGE_EH) == 0
2599 && (c = s->dest) != EXIT_BLOCK_PTR
2600 && c->pred->pred_next == NULL
2601 /* If the jump insn has side effects, we can't kill the edge. */
2602 && (GET_CODE (b->end) != JUMP_INSN
2603 || onlyjump_p (b->end))
2604 && merge_blocks (s, b, c))
2607 /* Don't get confused by the index shift caused by deleting blocks. */
2612 /* The given edge should potentially be a fallthru edge. If that is in
2613 fact true, delete the jump and barriers that are in the way. */
2616 tidy_fallthru_edge (e, b, c)
2622 /* ??? In a late-running flow pass, other folks may have deleted basic
2623 blocks by nopping out blocks, leaving multiple BARRIERs between here
2624 and the target label. They ought to be chastized and fixed.
2626 We can also wind up with a sequence of undeletable labels between
2627 one block and the next.
2629 So search through a sequence of barriers, labels, and notes for
2630 the head of block C and assert that we really do fall through. */
2632 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
2635 /* Remove what will soon cease being the jump insn from the source block.
2636 If block B consisted only of this single jump, turn it into a deleted
2639 if (GET_CODE (q) == JUMP_INSN
2641 && (any_uncondjump_p (q)
2642 || (b->succ == e && e->succ_next == NULL)))
2645 /* If this was a conditional jump, we need to also delete
2646 the insn that set cc0. */
2647 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
2654 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
2655 NOTE_SOURCE_FILE (q) = 0;
2663 /* Selectively unlink the sequence. */
2664 if (q != PREV_INSN (c->head))
2665 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
2667 e->flags |= EDGE_FALLTHRU;
2670 /* Fix up edges that now fall through, or rather should now fall through
2671 but previously required a jump around now deleted blocks. Simplify
2672 the search by only examining blocks numerically adjacent, since this
2673 is how find_basic_blocks created them. */
2676 tidy_fallthru_edges ()
2680 for (i = 1; i < n_basic_blocks; ++i)
2682 basic_block b = BASIC_BLOCK (i - 1);
2683 basic_block c = BASIC_BLOCK (i);
2686 /* We care about simple conditional or unconditional jumps with
2689 If we had a conditional branch to the next instruction when
2690 find_basic_blocks was called, then there will only be one
2691 out edge for the block which ended with the conditional
2692 branch (since we do not create duplicate edges).
2694 Furthermore, the edge will be marked as a fallthru because we
2695 merge the flags for the duplicate edges. So we do not want to
2696 check that the edge is not a FALLTHRU edge. */
2697 if ((s = b->succ) != NULL
2698 && s->succ_next == NULL
2700 /* If the jump insn has side effects, we can't tidy the edge. */
2701 && (GET_CODE (b->end) != JUMP_INSN
2702 || onlyjump_p (b->end)))
2703 tidy_fallthru_edge (s, b, c);
2707 /* Perform data flow analysis.
2708 F is the first insn of the function; FLAGS is a set of PROP_* flags
2709 to be used in accumulating flow info. */
2712 life_analysis (f, file, flags)
2717 #ifdef ELIMINABLE_REGS
2719 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
2722 /* Record which registers will be eliminated. We use this in
2725 CLEAR_HARD_REG_SET (elim_reg_set);
2727 #ifdef ELIMINABLE_REGS
2728 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
2729 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
2731 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
2735 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
2737 /* The post-reload life analysis have (on a global basis) the same
2738 registers live as was computed by reload itself. elimination
2739 Otherwise offsets and such may be incorrect.
2741 Reload will make some registers as live even though they do not
2744 We don't want to create new auto-incs after reload, since they
2745 are unlikely to be useful and can cause problems with shared
2747 if (reload_completed)
2748 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
2750 /* We want alias analysis information for local dead store elimination. */
2751 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2752 init_alias_analysis ();
2754 /* Always remove no-op moves. Do this before other processing so
2755 that we don't have to keep re-scanning them. */
2756 delete_noop_moves (f);
2758 /* Some targets can emit simpler epilogues if they know that sp was
2759 not ever modified during the function. After reload, of course,
2760 we've already emitted the epilogue so there's no sense searching. */
2761 if (! reload_completed)
2762 notice_stack_pointer_modification (f);
2764 /* Allocate and zero out data structures that will record the
2765 data from lifetime analysis. */
2766 allocate_reg_life_data ();
2767 allocate_bb_life_data ();
2769 /* Find the set of registers live on function exit. */
2770 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
2772 /* "Update" life info from zero. It'd be nice to begin the
2773 relaxation with just the exit and noreturn blocks, but that set
2774 is not immediately handy. */
2776 if (flags & PROP_REG_INFO)
2777 memset (regs_ever_live, 0, sizeof (regs_ever_live));
2778 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
2781 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2782 end_alias_analysis ();
2785 dump_flow_info (file);
2787 free_basic_block_vars (1);
2790 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2791 Search for REGNO. If found, abort if it is not wider than word_mode. */
2794 verify_wide_reg_1 (px, pregno)
2799 unsigned int regno = *(int *) pregno;
2801 if (GET_CODE (x) == REG && REGNO (x) == regno)
2803 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
2810 /* A subroutine of verify_local_live_at_start. Search through insns
2811 between HEAD and END looking for register REGNO. */
2814 verify_wide_reg (regno, head, end)
2821 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
2825 head = NEXT_INSN (head);
2828 /* We didn't find the register at all. Something's way screwy. */
2832 /* A subroutine of update_life_info. Verify that there are no untoward
2833 changes in live_at_start during a local update. */
2836 verify_local_live_at_start (new_live_at_start, bb)
2837 regset new_live_at_start;
2840 if (reload_completed)
2842 /* After reload, there are no pseudos, nor subregs of multi-word
2843 registers. The regsets should exactly match. */
2844 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
2851 /* Find the set of changed registers. */
2852 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
2854 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
2856 /* No registers should die. */
2857 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
2859 /* Verify that the now-live register is wider than word_mode. */
2860 verify_wide_reg (i, bb->head, bb->end);
2865 /* Updates life information starting with the basic blocks set in BLOCKS.
2866 If BLOCKS is null, consider it to be the universal set.
2868 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
2869 we are only expecting local modifications to basic blocks. If we find
2870 extra registers live at the beginning of a block, then we either killed
2871 useful data, or we have a broken split that wants data not provided.
2872 If we find registers removed from live_at_start, that means we have
2873 a broken peephole that is killing a register it shouldn't.
2875 ??? This is not true in one situation -- when a pre-reload splitter
2876 generates subregs of a multi-word pseudo, current life analysis will
2877 lose the kill. So we _can_ have a pseudo go live. How irritating.
2879 Including PROP_REG_INFO does not properly refresh regs_ever_live
2880 unless the caller resets it to zero. */
2883 update_life_info (blocks, extent, prop_flags)
2885 enum update_life_extent extent;
2889 regset_head tmp_head;
2892 tmp = INITIALIZE_REG_SET (tmp_head);
2894 /* For a global update, we go through the relaxation process again. */
2895 if (extent != UPDATE_LIFE_LOCAL)
2897 calculate_global_regs_live (blocks, blocks,
2898 prop_flags & PROP_SCAN_DEAD_CODE);
2900 /* If asked, remove notes from the blocks we'll update. */
2901 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
2902 count_or_remove_death_notes (blocks, 1);
2907 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2909 basic_block bb = BASIC_BLOCK (i);
2911 COPY_REG_SET (tmp, bb->global_live_at_end);
2912 propagate_block (bb, tmp, (regset) NULL, prop_flags);
2914 if (extent == UPDATE_LIFE_LOCAL)
2915 verify_local_live_at_start (tmp, bb);
2920 for (i = n_basic_blocks - 1; i >= 0; --i)
2922 basic_block bb = BASIC_BLOCK (i);
2924 COPY_REG_SET (tmp, bb->global_live_at_end);
2925 propagate_block (bb, tmp, (regset) NULL, prop_flags);
2927 if (extent == UPDATE_LIFE_LOCAL)
2928 verify_local_live_at_start (tmp, bb);
2934 if (prop_flags & PROP_REG_INFO)
2936 /* The only pseudos that are live at the beginning of the function
2937 are those that were not set anywhere in the function. local-alloc
2938 doesn't know how to handle these correctly, so mark them as not
2939 local to any one basic block. */
2940 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
2941 FIRST_PSEUDO_REGISTER, i,
2942 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
2944 /* We have a problem with any pseudoreg that lives across the setjmp.
2945 ANSI says that if a user variable does not change in value between
2946 the setjmp and the longjmp, then the longjmp preserves it. This
2947 includes longjmp from a place where the pseudo appears dead.
2948 (In principle, the value still exists if it is in scope.)
2949 If the pseudo goes in a hard reg, some other value may occupy
2950 that hard reg where this pseudo is dead, thus clobbering the pseudo.
2951 Conclusion: such a pseudo must not go in a hard reg. */
2952 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
2953 FIRST_PSEUDO_REGISTER, i,
2955 if (regno_reg_rtx[i] != 0)
2957 REG_LIVE_LENGTH (i) = -1;
2958 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
2964 /* Free the variables allocated by find_basic_blocks.
2966 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
2969 free_basic_block_vars (keep_head_end_p)
2970 int keep_head_end_p;
2972 if (basic_block_for_insn)
2974 VARRAY_FREE (basic_block_for_insn);
2975 basic_block_for_insn = NULL;
2978 if (! keep_head_end_p)
2981 VARRAY_FREE (basic_block_info);
2984 ENTRY_BLOCK_PTR->aux = NULL;
2985 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
2986 EXIT_BLOCK_PTR->aux = NULL;
2987 EXIT_BLOCK_PTR->global_live_at_start = NULL;
2991 /* Return nonzero if the destination of SET equals the source. */
2997 rtx src = SET_SRC (set);
2998 rtx dst = SET_DEST (set);
3000 if (GET_CODE (src) == SUBREG && GET_CODE (dst) == SUBREG)
3002 if (SUBREG_WORD (src) != SUBREG_WORD (dst))
3004 src = SUBREG_REG (src);
3005 dst = SUBREG_REG (dst);
3008 return (GET_CODE (src) == REG && GET_CODE (dst) == REG
3009 && REGNO (src) == REGNO (dst));
3012 /* Return nonzero if an insn consists only of SETs, each of which only sets a
3019 rtx pat = PATTERN (insn);
3021 /* Insns carrying these notes are useful later on. */
3022 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
3025 if (GET_CODE (pat) == SET && set_noop_p (pat))
3028 if (GET_CODE (pat) == PARALLEL)
3031 /* If nothing but SETs of registers to themselves,
3032 this insn can also be deleted. */
3033 for (i = 0; i < XVECLEN (pat, 0); i++)
3035 rtx tem = XVECEXP (pat, 0, i);
3037 if (GET_CODE (tem) == USE
3038 || GET_CODE (tem) == CLOBBER)
3041 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
3050 /* Delete any insns that copy a register to itself. */
3053 delete_noop_moves (f)
3057 for (insn = f; insn; insn = NEXT_INSN (insn))
3059 if (GET_CODE (insn) == INSN && noop_move_p (insn))
3061 PUT_CODE (insn, NOTE);
3062 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3063 NOTE_SOURCE_FILE (insn) = 0;
3068 /* Determine if the stack pointer is constant over the life of the function.
3069 Only useful before prologues have been emitted. */
3072 notice_stack_pointer_modification_1 (x, pat, data)
3074 rtx pat ATTRIBUTE_UNUSED;
3075 void *data ATTRIBUTE_UNUSED;
3077 if (x == stack_pointer_rtx
3078 /* The stack pointer is only modified indirectly as the result
3079 of a push until later in flow. See the comments in rtl.texi
3080 regarding Embedded Side-Effects on Addresses. */
3081 || (GET_CODE (x) == MEM
3082 && (GET_CODE (XEXP (x, 0)) == PRE_DEC
3083 || GET_CODE (XEXP (x, 0)) == PRE_INC
3084 || GET_CODE (XEXP (x, 0)) == POST_DEC
3085 || GET_CODE (XEXP (x, 0)) == POST_INC)
3086 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
3087 current_function_sp_is_unchanging = 0;
3091 notice_stack_pointer_modification (f)
3096 /* Assume that the stack pointer is unchanging if alloca hasn't
3098 current_function_sp_is_unchanging = !current_function_calls_alloca;
3099 if (! current_function_sp_is_unchanging)
3102 for (insn = f; insn; insn = NEXT_INSN (insn))
3106 /* Check if insn modifies the stack pointer. */
3107 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
3109 if (! current_function_sp_is_unchanging)
3115 /* Mark a register in SET. Hard registers in large modes get all
3116 of their component registers set as well. */
3119 mark_reg (reg, xset)
3123 regset set = (regset) xset;
3124 int regno = REGNO (reg);
3126 if (GET_MODE (reg) == BLKmode)
3129 SET_REGNO_REG_SET (set, regno);
3130 if (regno < FIRST_PSEUDO_REGISTER)
3132 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3134 SET_REGNO_REG_SET (set, regno + n);
3138 /* Mark those regs which are needed at the end of the function as live
3139 at the end of the last basic block. */
3142 mark_regs_live_at_end (set)
3147 /* If exiting needs the right stack value, consider the stack pointer
3148 live at the end of the function. */
3149 if ((HAVE_epilogue && reload_completed)
3150 || ! EXIT_IGNORE_STACK
3151 || (! FRAME_POINTER_REQUIRED
3152 && ! current_function_calls_alloca
3153 && flag_omit_frame_pointer)
3154 || current_function_sp_is_unchanging)
3156 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
3159 /* Mark the frame pointer if needed at the end of the function. If
3160 we end up eliminating it, it will be removed from the live list
3161 of each basic block by reload. */
3163 if (! reload_completed || frame_pointer_needed)
3165 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
3166 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3167 /* If they are different, also mark the hard frame pointer as live. */
3168 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
3169 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
3173 #ifdef PIC_OFFSET_TABLE_REGNUM
3174 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
3175 /* Many architectures have a GP register even without flag_pic.
3176 Assume the pic register is not in use, or will be handled by
3177 other means, if it is not fixed. */
3178 if (fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3179 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
3183 /* Mark all global registers, and all registers used by the epilogue
3184 as being live at the end of the function since they may be
3185 referenced by our caller. */
3186 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3187 if (global_regs[i] || EPILOGUE_USES (i))
3188 SET_REGNO_REG_SET (set, i);
3190 /* Mark all call-saved registers that we actaully used. */
3191 if (HAVE_epilogue && reload_completed)
3193 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3194 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
3195 SET_REGNO_REG_SET (set, i);
3198 /* Mark function return value. */
3199 diddle_return_value (mark_reg, set);
3202 /* Callback function for for_each_successor_phi. DATA is a regset.
3203 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3204 INSN, in the regset. */
3207 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
3208 rtx insn ATTRIBUTE_UNUSED;
3209 int dest_regno ATTRIBUTE_UNUSED;
3213 regset live = (regset) data;
3214 SET_REGNO_REG_SET (live, src_regno);
3218 /* Propagate global life info around the graph of basic blocks. Begin
3219 considering blocks with their corresponding bit set in BLOCKS_IN.
3220 If BLOCKS_IN is null, consider it the universal set.
3222 BLOCKS_OUT is set for every block that was changed. */
3225 calculate_global_regs_live (blocks_in, blocks_out, flags)
3226 sbitmap blocks_in, blocks_out;
3229 basic_block *queue, *qhead, *qtail, *qend;
3230 regset tmp, new_live_at_end;
3231 regset_head tmp_head;
3232 regset_head new_live_at_end_head;
3235 tmp = INITIALIZE_REG_SET (tmp_head);
3236 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
3238 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3239 because the `head == tail' style test for an empty queue doesn't
3240 work with a full queue. */
3241 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3243 qhead = qend = queue + n_basic_blocks + 2;
3245 /* Clear out the garbage that might be hanging out in bb->aux. */
3246 for (i = n_basic_blocks - 1; i >= 0; --i)
3247 BASIC_BLOCK (i)->aux = NULL;
3249 /* Queue the blocks set in the initial mask. Do this in reverse block
3250 number order so that we are more likely for the first round to do
3251 useful work. We use AUX non-null to flag that the block is queued. */
3254 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3256 basic_block bb = BASIC_BLOCK (i);
3263 for (i = 0; i < n_basic_blocks; ++i)
3265 basic_block bb = BASIC_BLOCK (i);
3272 sbitmap_zero (blocks_out);
3274 while (qhead != qtail)
3276 int rescan, changed;
3285 /* Begin by propogating live_at_start from the successor blocks. */
3286 CLEAR_REG_SET (new_live_at_end);
3287 for (e = bb->succ; e; e = e->succ_next)
3289 basic_block sb = e->dest;
3290 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3293 /* Force the stack pointer to be live -- which might not already be
3294 the case for blocks within infinite loops. */
3295 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3297 /* Similarly for the frame pointer before reload. Any reference
3298 to any pseudo before reload is a potential reference of the
3300 if (! reload_completed)
3301 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3303 /* Regs used in phi nodes are not included in
3304 global_live_at_start, since they are live only along a
3305 particular edge. Set those regs that are live because of a
3306 phi node alternative corresponding to this particular block. */
3308 for_each_successor_phi (bb, &set_phi_alternative_reg,
3311 if (bb == ENTRY_BLOCK_PTR)
3313 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3317 /* On our first pass through this block, we'll go ahead and continue.
3318 Recognize first pass by local_set NULL. On subsequent passes, we
3319 get to skip out early if live_at_end wouldn't have changed. */
3321 if (bb->local_set == NULL)
3323 bb->local_set = OBSTACK_ALLOC_REG_SET (function_obstack);
3328 /* If any bits were removed from live_at_end, we'll have to
3329 rescan the block. This wouldn't be necessary if we had
3330 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3331 local_live is really dependent on live_at_end. */
3332 CLEAR_REG_SET (tmp);
3333 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3334 new_live_at_end, BITMAP_AND_COMPL);
3338 /* Find the set of changed bits. Take this opportunity
3339 to notice that this set is empty and early out. */
3340 CLEAR_REG_SET (tmp);
3341 changed = bitmap_operation (tmp, bb->global_live_at_end,
3342 new_live_at_end, BITMAP_XOR);
3346 /* If any of the changed bits overlap with local_set,
3347 we'll have to rescan the block. Detect overlap by
3348 the AND with ~local_set turning off bits. */
3349 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3354 /* Let our caller know that BB changed enough to require its
3355 death notes updated. */
3357 SET_BIT (blocks_out, bb->index);
3361 /* Add to live_at_start the set of all registers in
3362 new_live_at_end that aren't in the old live_at_end. */
3364 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3366 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3368 changed = bitmap_operation (bb->global_live_at_start,
3369 bb->global_live_at_start,
3376 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3378 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3379 into live_at_start. */
3380 propagate_block (bb, new_live_at_end, bb->local_set, flags);
3382 /* If live_at start didn't change, no need to go farther. */
3383 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3386 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3389 /* Queue all predecessors of BB so that we may re-examine
3390 their live_at_end. */
3391 for (e = bb->pred; e; e = e->pred_next)
3393 basic_block pb = e->src;
3394 if (pb->aux == NULL)
3405 FREE_REG_SET (new_live_at_end);
3409 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3411 basic_block bb = BASIC_BLOCK (i);
3412 FREE_REG_SET (bb->local_set);
3417 for (i = n_basic_blocks - 1; i >= 0; --i)
3419 basic_block bb = BASIC_BLOCK (i);
3420 FREE_REG_SET (bb->local_set);
3427 /* Subroutines of life analysis. */
3429 /* Allocate the permanent data structures that represent the results
3430 of life analysis. Not static since used also for stupid life analysis. */
3433 allocate_bb_life_data ()
3437 for (i = 0; i < n_basic_blocks; i++)
3439 basic_block bb = BASIC_BLOCK (i);
3441 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
3442 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
3445 ENTRY_BLOCK_PTR->global_live_at_end
3446 = OBSTACK_ALLOC_REG_SET (function_obstack);
3447 EXIT_BLOCK_PTR->global_live_at_start
3448 = OBSTACK_ALLOC_REG_SET (function_obstack);
3450 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (function_obstack);
3454 allocate_reg_life_data ()
3458 max_regno = max_reg_num ();
3460 /* Recalculate the register space, in case it has grown. Old style
3461 vector oriented regsets would set regset_{size,bytes} here also. */
3462 allocate_reg_info (max_regno, FALSE, FALSE);
3464 /* Reset all the data we'll collect in propagate_block and its
3466 for (i = 0; i < max_regno; i++)
3470 REG_N_DEATHS (i) = 0;
3471 REG_N_CALLS_CROSSED (i) = 0;
3472 REG_LIVE_LENGTH (i) = 0;
3473 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3477 /* Delete dead instructions for propagate_block. */
3480 propagate_block_delete_insn (bb, insn)
3484 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3486 /* If the insn referred to a label, and that label was attached to
3487 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3488 pretty much mandatory to delete it, because the ADDR_VEC may be
3489 referencing labels that no longer exist. */
3493 rtx label = XEXP (inote, 0);
3496 if (LABEL_NUSES (label) == 1
3497 && (next = next_nonnote_insn (label)) != NULL
3498 && GET_CODE (next) == JUMP_INSN
3499 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3500 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3502 rtx pat = PATTERN (next);
3503 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3504 int len = XVECLEN (pat, diff_vec_p);
3507 for (i = 0; i < len; i++)
3508 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3510 flow_delete_insn (next);
3514 if (bb->end == insn)
3515 bb->end = PREV_INSN (insn);
3516 flow_delete_insn (insn);
3519 /* Delete dead libcalls for propagate_block. Return the insn
3520 before the libcall. */
3523 propagate_block_delete_libcall (bb, insn, note)
3527 rtx first = XEXP (note, 0);
3528 rtx before = PREV_INSN (first);
3530 if (insn == bb->end)
3533 flow_delete_insn_chain (first, insn);
3537 /* Update the life-status of regs for one insn. Return the previous insn. */
3540 propagate_one_insn (pbi, insn)
3541 struct propagate_block_info *pbi;
3544 rtx prev = PREV_INSN (insn);
3545 int flags = pbi->flags;
3546 int insn_is_dead = 0;
3547 int libcall_is_dead = 0;
3551 if (! INSN_P (insn))
3554 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3555 if (flags & PROP_SCAN_DEAD_CODE)
3557 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0,
3559 libcall_is_dead = (insn_is_dead && note != 0
3560 && libcall_dead_p (pbi, note, insn));
3563 /* We almost certainly don't want to delete prologue or epilogue
3564 instructions. Warn about probable compiler losage. */
3567 && (((HAVE_epilogue || HAVE_prologue)
3568 && prologue_epilogue_contains (insn))
3569 || (HAVE_sibcall_epilogue
3570 && sibcall_epilogue_contains (insn)))
3571 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
3573 if (flags & PROP_KILL_DEAD_CODE)
3575 warning ("ICE: would have deleted prologue/epilogue insn");
3576 if (!inhibit_warnings)
3579 libcall_is_dead = insn_is_dead = 0;
3582 /* If an instruction consists of just dead store(s) on final pass,
3584 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3586 /* Record sets. Do this even for dead instructions, since they
3587 would have killed the values if they hadn't been deleted. */
3588 mark_set_regs (pbi, PATTERN (insn), insn);
3590 /* CC0 is now known to be dead. Either this insn used it,
3591 in which case it doesn't anymore, or clobbered it,
3592 so the next insn can't use it. */
3595 if (libcall_is_dead)
3597 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
3598 insn = NEXT_INSN (prev);
3601 propagate_block_delete_insn (pbi->bb, insn);
3606 /* See if this is an increment or decrement that can be merged into
3607 a following memory address. */
3610 register rtx x = single_set (insn);
3612 /* Does this instruction increment or decrement a register? */
3613 if ((flags & PROP_AUTOINC)
3615 && GET_CODE (SET_DEST (x)) == REG
3616 && (GET_CODE (SET_SRC (x)) == PLUS
3617 || GET_CODE (SET_SRC (x)) == MINUS)
3618 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3619 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3620 /* Ok, look for a following memory ref we can combine with.
3621 If one is found, change the memory ref to a PRE_INC
3622 or PRE_DEC, cancel this insn, and return 1.
3623 Return 0 if nothing has been done. */
3624 && try_pre_increment_1 (pbi, insn))
3627 #endif /* AUTO_INC_DEC */
3629 CLEAR_REG_SET (pbi->new_set);
3631 /* If this is not the final pass, and this insn is copying the value of
3632 a library call and it's dead, don't scan the insns that perform the
3633 library call, so that the call's arguments are not marked live. */
3634 if (libcall_is_dead)
3636 /* Record the death of the dest reg. */
3637 mark_set_regs (pbi, PATTERN (insn), insn);
3639 insn = XEXP (note, 0);
3640 return PREV_INSN (insn);
3642 else if (GET_CODE (PATTERN (insn)) == SET
3643 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3644 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3645 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3646 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3647 /* We have an insn to pop a constant amount off the stack.
3648 (Such insns use PLUS regardless of the direction of the stack,
3649 and any insn to adjust the stack by a constant is always a pop.)
3650 These insns, if not dead stores, have no effect on life. */
3654 /* Any regs live at the time of a call instruction must not go
3655 in a register clobbered by calls. Find all regs now live and
3656 record this for them. */
3658 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
3659 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3660 { REG_N_CALLS_CROSSED (i)++; });
3662 /* Record sets. Do this even for dead instructions, since they
3663 would have killed the values if they hadn't been deleted. */
3664 mark_set_regs (pbi, PATTERN (insn), insn);
3666 if (GET_CODE (insn) == CALL_INSN)
3672 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3673 cond = COND_EXEC_TEST (PATTERN (insn));
3675 /* Non-constant calls clobber memory. */
3676 if (! CONST_CALL_P (insn))
3677 free_EXPR_LIST_list (&pbi->mem_set_list);
3679 /* There may be extra registers to be clobbered. */
3680 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3682 note = XEXP (note, 1))
3683 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
3684 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
3685 cond, insn, pbi->flags);
3687 /* Calls change all call-used and global registers. */
3688 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3689 if (call_used_regs[i] && ! global_regs[i]
3692 /* We do not want REG_UNUSED notes for these registers. */
3693 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
3695 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
3699 /* If an insn doesn't use CC0, it becomes dead since we assume
3700 that every insn clobbers it. So show it dead here;
3701 mark_used_regs will set it live if it is referenced. */
3706 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
3708 /* Sometimes we may have inserted something before INSN (such as a move)
3709 when we make an auto-inc. So ensure we will scan those insns. */
3711 prev = PREV_INSN (insn);
3714 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3720 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3721 cond = COND_EXEC_TEST (PATTERN (insn));
3723 /* Calls use their arguments. */
3724 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3726 note = XEXP (note, 1))
3727 if (GET_CODE (XEXP (note, 0)) == USE)
3728 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
3731 /* The stack ptr is used (honorarily) by a CALL insn. */
3732 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
3734 /* Calls may also reference any of the global registers,
3735 so they are made live. */
3736 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3738 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
3743 /* On final pass, update counts of how many insns in which each reg
3745 if (flags & PROP_REG_INFO)
3746 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3747 { REG_LIVE_LENGTH (i)++; });
3752 /* Initialize a propagate_block_info struct for public consumption.
3753 Note that the structure itself is opaque to this file, but that
3754 the user can use the regsets provided here. */
3756 struct propagate_block_info *
3757 init_propagate_block_info (bb, live, local_set, flags)
3763 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
3766 pbi->reg_live = live;
3767 pbi->mem_set_list = NULL_RTX;
3768 pbi->local_set = local_set;
3772 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3773 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
3775 pbi->reg_next_use = NULL;
3777 pbi->new_set = BITMAP_XMALLOC ();
3779 #ifdef HAVE_conditional_execution
3780 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
3781 free_reg_cond_life_info);
3782 pbi->reg_cond_reg = BITMAP_XMALLOC ();
3784 /* If this block ends in a conditional branch, for each register live
3785 from one side of the branch and not the other, record the register
3786 as conditionally dead. */
3787 if ((flags & (PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE))
3788 && GET_CODE (bb->end) == JUMP_INSN
3789 && any_condjump_p (bb->end))
3791 regset_head diff_head;
3792 regset diff = INITIALIZE_REG_SET (diff_head);
3793 basic_block bb_true, bb_false;
3794 rtx cond_true, cond_false, set_src;
3797 /* Identify the successor blocks. */
3798 bb_true = bb->succ->dest;
3799 if (bb->succ->succ_next != NULL)
3801 bb_false = bb->succ->succ_next->dest;
3803 if (bb->succ->flags & EDGE_FALLTHRU)
3805 basic_block t = bb_false;
3809 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
3814 /* This can happen with a conditional jump to the next insn. */
3815 if (JUMP_LABEL (bb->end) != bb_true->head)
3818 /* Simplest way to do nothing. */
3822 /* Extract the condition from the branch. */
3823 set_src = SET_SRC (pc_set (bb->end));
3824 cond_true = XEXP (set_src, 0);
3825 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
3826 GET_MODE (cond_true), XEXP (cond_true, 0),
3827 XEXP (cond_true, 1));
3828 if (GET_CODE (XEXP (set_src, 1)) == PC)
3831 cond_false = cond_true;
3835 /* Compute which register lead different lives in the successors. */
3836 if (bitmap_operation (diff, bb_true->global_live_at_start,
3837 bb_false->global_live_at_start, BITMAP_XOR))
3839 rtx reg = XEXP (cond_true, 0);
3841 if (GET_CODE (reg) == SUBREG)
3842 reg = SUBREG_REG (reg);
3844 if (GET_CODE (reg) != REG)
3847 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
3849 /* For each such register, mark it conditionally dead. */
3850 EXECUTE_IF_SET_IN_REG_SET
3853 struct reg_cond_life_info *rcli;
3856 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3858 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
3862 rcli->condition = alloc_EXPR_LIST (0, cond, NULL_RTX);
3864 splay_tree_insert (pbi->reg_cond_dead, i,
3865 (splay_tree_value) rcli);
3869 FREE_REG_SET (diff);
3873 /* If this block has no successors, any stores to the frame that aren't
3874 used later in the block are dead. So make a pass over the block
3875 recording any such that are made and show them dead at the end. We do
3876 a very conservative and simple job here. */
3878 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
3879 && (TYPE_RETURNS_STACK_DEPRESSED
3880 (TREE_TYPE (current_function_decl))))
3881 && (flags & PROP_SCAN_DEAD_CODE)
3882 && (bb->succ == NULL
3883 || (bb->succ->succ_next == NULL
3884 && bb->succ->dest == EXIT_BLOCK_PTR)))
3887 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
3888 if (GET_CODE (insn) == INSN
3889 && GET_CODE (PATTERN (insn)) == SET
3890 && GET_CODE (SET_DEST (PATTERN (insn))) == MEM)
3892 rtx mem = SET_DEST (PATTERN (insn));
3894 if (XEXP (mem, 0) == frame_pointer_rtx
3895 || (GET_CODE (XEXP (mem, 0)) == PLUS
3896 && XEXP (XEXP (mem, 0), 0) == frame_pointer_rtx
3897 && GET_CODE (XEXP (XEXP (mem, 0), 1)) == CONST_INT))
3898 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
3905 /* Release a propagate_block_info struct. */
3908 free_propagate_block_info (pbi)
3909 struct propagate_block_info *pbi;
3911 free_EXPR_LIST_list (&pbi->mem_set_list);
3913 BITMAP_XFREE (pbi->new_set);
3915 #ifdef HAVE_conditional_execution
3916 splay_tree_delete (pbi->reg_cond_dead);
3917 BITMAP_XFREE (pbi->reg_cond_reg);
3920 if (pbi->reg_next_use)
3921 free (pbi->reg_next_use);
3926 /* Compute the registers live at the beginning of a basic block BB from
3927 those live at the end.
3929 When called, REG_LIVE contains those live at the end. On return, it
3930 contains those live at the beginning.
3932 LOCAL_SET, if non-null, will be set with all registers killed by
3933 this basic block. */
3936 propagate_block (bb, live, local_set, flags)
3942 struct propagate_block_info *pbi;
3945 pbi = init_propagate_block_info (bb, live, local_set, flags);
3947 if (flags & PROP_REG_INFO)
3951 /* Process the regs live at the end of the block.
3952 Mark them as not local to any one basic block. */
3953 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
3954 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
3957 /* Scan the block an insn at a time from end to beginning. */
3959 for (insn = bb->end;; insn = prev)
3961 /* If this is a call to `setjmp' et al, warn if any
3962 non-volatile datum is live. */
3963 if ((flags & PROP_REG_INFO)
3964 && GET_CODE (insn) == NOTE
3965 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
3966 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
3968 prev = propagate_one_insn (pbi, insn);
3970 if (insn == bb->head)
3974 free_propagate_block_info (pbi);
3977 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
3978 (SET expressions whose destinations are registers dead after the insn).
3979 NEEDED is the regset that says which regs are alive after the insn.
3981 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
3983 If X is the entire body of an insn, NOTES contains the reg notes
3984 pertaining to the insn. */
3987 insn_dead_p (pbi, x, call_ok, notes)
3988 struct propagate_block_info *pbi;
3991 rtx notes ATTRIBUTE_UNUSED;
3993 enum rtx_code code = GET_CODE (x);
3996 /* If flow is invoked after reload, we must take existing AUTO_INC
3997 expresions into account. */
3998 if (reload_completed)
4000 for (; notes; notes = XEXP (notes, 1))
4002 if (REG_NOTE_KIND (notes) == REG_INC)
4004 int regno = REGNO (XEXP (notes, 0));
4006 /* Don't delete insns to set global regs. */
4007 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4008 || REGNO_REG_SET_P (pbi->reg_live, regno))
4015 /* If setting something that's a reg or part of one,
4016 see if that register's altered value will be live. */
4020 rtx r = SET_DEST (x);
4023 if (GET_CODE (r) == CC0)
4024 return ! pbi->cc0_live;
4027 /* A SET that is a subroutine call cannot be dead. */
4028 if (GET_CODE (SET_SRC (x)) == CALL)
4034 /* Don't eliminate loads from volatile memory or volatile asms. */
4035 else if (volatile_refs_p (SET_SRC (x)))
4038 if (GET_CODE (r) == MEM)
4042 if (MEM_VOLATILE_P (r))
4045 /* Walk the set of memory locations we are currently tracking
4046 and see if one is an identical match to this memory location.
4047 If so, this memory write is dead (remember, we're walking
4048 backwards from the end of the block to the start). */
4049 temp = pbi->mem_set_list;
4052 rtx mem = XEXP (temp, 0);
4054 if (rtx_equal_p (mem, r))
4057 /* Check if memory reference matches an auto increment. Only
4058 post increment/decrement or modify are valid. */
4059 if (GET_MODE (mem) == GET_MODE (r)
4060 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4061 || GET_CODE (XEXP (mem, 0)) == POST_INC
4062 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4063 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4064 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4067 temp = XEXP (temp, 1);
4072 while (GET_CODE (r) == SUBREG
4073 || GET_CODE (r) == STRICT_LOW_PART
4074 || GET_CODE (r) == ZERO_EXTRACT)
4077 if (GET_CODE (r) == REG)
4079 int regno = REGNO (r);
4082 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4085 /* If this is a hard register, verify that subsequent
4086 words are not needed. */
4087 if (regno < FIRST_PSEUDO_REGISTER)
4089 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4092 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4096 /* Don't delete insns to set global regs. */
4097 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4100 /* Make sure insns to set the stack pointer aren't deleted. */
4101 if (regno == STACK_POINTER_REGNUM)
4104 /* Make sure insns to set the frame pointer aren't deleted. */
4105 if (regno == FRAME_POINTER_REGNUM
4106 && (! reload_completed || frame_pointer_needed))
4108 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4109 if (regno == HARD_FRAME_POINTER_REGNUM
4110 && (! reload_completed || frame_pointer_needed))
4114 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4115 /* Make sure insns to set arg pointer are never deleted
4116 (if the arg pointer isn't fixed, there will be a USE
4117 for it, so we can treat it normally). */
4118 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4122 #ifdef PIC_OFFSET_TABLE_REGNUM
4123 /* Before reload, do not allow sets of the pic register
4124 to be deleted. Reload can insert references to
4125 constant pool memory anywhere in the function, making
4126 the PIC register live where it wasn't before. */
4127 if (regno == PIC_OFFSET_TABLE_REGNUM && fixed_regs[regno]
4128 && ! reload_completed)
4132 /* Otherwise, the set is dead. */
4138 /* If performing several activities, insn is dead if each activity
4139 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4140 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4142 else if (code == PARALLEL)
4144 int i = XVECLEN (x, 0);
4146 for (i--; i >= 0; i--)
4147 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4148 && GET_CODE (XVECEXP (x, 0, i)) != USE
4149 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4155 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4156 is not necessarily true for hard registers. */
4157 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4158 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4159 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4162 /* We do not check other CLOBBER or USE here. An insn consisting of just
4163 a CLOBBER or just a USE should not be deleted. */
4167 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4168 return 1 if the entire library call is dead.
4169 This is true if INSN copies a register (hard or pseudo)
4170 and if the hard return reg of the call insn is dead.
4171 (The caller should have tested the destination of the SET inside
4172 INSN already for death.)
4174 If this insn doesn't just copy a register, then we don't
4175 have an ordinary libcall. In that case, cse could not have
4176 managed to substitute the source for the dest later on,
4177 so we can assume the libcall is dead.
4179 PBI is the block info giving pseudoregs live before this insn.
4180 NOTE is the REG_RETVAL note of the insn. */
4183 libcall_dead_p (pbi, note, insn)
4184 struct propagate_block_info *pbi;
4188 rtx x = single_set (insn);
4192 register rtx r = SET_SRC (x);
4193 if (GET_CODE (r) == REG)
4195 rtx call = XEXP (note, 0);
4199 /* Find the call insn. */
4200 while (call != insn && GET_CODE (call) != CALL_INSN)
4201 call = NEXT_INSN (call);
4203 /* If there is none, do nothing special,
4204 since ordinary death handling can understand these insns. */
4208 /* See if the hard reg holding the value is dead.
4209 If this is a PARALLEL, find the call within it. */
4210 call_pat = PATTERN (call);
4211 if (GET_CODE (call_pat) == PARALLEL)
4213 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4214 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4215 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4218 /* This may be a library call that is returning a value
4219 via invisible pointer. Do nothing special, since
4220 ordinary death handling can understand these insns. */
4224 call_pat = XVECEXP (call_pat, 0, i);
4227 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4233 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4234 live at function entry. Don't count global register variables, variables
4235 in registers that can be used for function arg passing, or variables in
4236 fixed hard registers. */
4239 regno_uninitialized (regno)
4242 if (n_basic_blocks == 0
4243 || (regno < FIRST_PSEUDO_REGISTER
4244 && (global_regs[regno]
4245 || fixed_regs[regno]
4246 || FUNCTION_ARG_REGNO_P (regno))))
4249 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
4252 /* 1 if register REGNO was alive at a place where `setjmp' was called
4253 and was set more than once or is an argument.
4254 Such regs may be clobbered by `longjmp'. */
4257 regno_clobbered_at_setjmp (regno)
4260 if (n_basic_blocks == 0)
4263 return ((REG_N_SETS (regno) > 1
4264 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
4265 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
4268 /* INSN references memory, possibly using autoincrement addressing modes.
4269 Find any entries on the mem_set_list that need to be invalidated due
4270 to an address change. */
4273 invalidate_mems_from_autoinc (pbi, insn)
4274 struct propagate_block_info *pbi;
4277 rtx note = REG_NOTES (insn);
4278 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
4280 if (REG_NOTE_KIND (note) == REG_INC)
4282 rtx temp = pbi->mem_set_list;
4283 rtx prev = NULL_RTX;
4288 next = XEXP (temp, 1);
4289 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
4291 /* Splice temp out of list. */
4293 XEXP (prev, 1) = next;
4295 pbi->mem_set_list = next;
4296 free_EXPR_LIST_node (temp);
4306 /* Process the registers that are set within X. Their bits are set to
4307 1 in the regset DEAD, because they are dead prior to this insn.
4309 If INSN is nonzero, it is the insn being processed.
4311 FLAGS is the set of operations to perform. */
4314 mark_set_regs (pbi, x, insn)
4315 struct propagate_block_info *pbi;
4318 rtx cond = NULL_RTX;
4323 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
4325 if (REG_NOTE_KIND (link) == REG_INC)
4326 mark_set_1 (pbi, SET, XEXP (link, 0),
4327 (GET_CODE (x) == COND_EXEC
4328 ? COND_EXEC_TEST (x) : NULL_RTX),
4332 switch (code = GET_CODE (x))
4336 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
4340 cond = COND_EXEC_TEST (x);
4341 x = COND_EXEC_CODE (x);
4347 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
4349 rtx sub = XVECEXP (x, 0, i);
4350 switch (code = GET_CODE (sub))
4353 if (cond != NULL_RTX)
4356 cond = COND_EXEC_TEST (sub);
4357 sub = COND_EXEC_CODE (sub);
4358 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
4364 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
4379 /* Process a single SET rtx, X. */
4382 mark_set_1 (pbi, code, reg, cond, insn, flags)
4383 struct propagate_block_info *pbi;
4385 rtx reg, cond, insn;
4388 int regno_first = -1, regno_last = -1;
4392 /* Some targets place small structures in registers for
4393 return values of functions. We have to detect this
4394 case specially here to get correct flow information. */
4395 if (GET_CODE (reg) == PARALLEL
4396 && GET_MODE (reg) == BLKmode)
4398 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
4399 mark_set_1 (pbi, code, XVECEXP (reg, 0, i), cond, insn, flags);
4403 /* Modifying just one hardware register of a multi-reg value or just a
4404 byte field of a register does not mean the value from before this insn
4405 is now dead. Of course, if it was dead after it's unused now. */
4407 switch (GET_CODE (reg))
4411 case STRICT_LOW_PART:
4412 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4414 reg = XEXP (reg, 0);
4415 while (GET_CODE (reg) == SUBREG
4416 || GET_CODE (reg) == ZERO_EXTRACT
4417 || GET_CODE (reg) == SIGN_EXTRACT
4418 || GET_CODE (reg) == STRICT_LOW_PART);
4419 if (GET_CODE (reg) == MEM)
4421 not_dead = REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
4425 regno_last = regno_first = REGNO (reg);
4426 if (regno_first < FIRST_PSEUDO_REGISTER)
4427 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
4431 if (GET_CODE (SUBREG_REG (reg)) == REG)
4433 enum machine_mode outer_mode = GET_MODE (reg);
4434 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
4436 /* Identify the range of registers affected. This is moderately
4437 tricky for hard registers. See alter_subreg. */
4439 regno_last = regno_first = REGNO (SUBREG_REG (reg));
4440 if (regno_first < FIRST_PSEUDO_REGISTER)
4442 #ifdef ALTER_HARD_SUBREG
4443 regno_first = ALTER_HARD_SUBREG (outer_mode, SUBREG_WORD (reg),
4444 inner_mode, regno_first);
4446 regno_first += SUBREG_WORD (reg);
4448 regno_last = (regno_first
4449 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
4451 /* Since we've just adjusted the register number ranges, make
4452 sure REG matches. Otherwise some_was_live will be clear
4453 when it shouldn't have been, and we'll create incorrect
4454 REG_UNUSED notes. */
4455 reg = gen_rtx_REG (outer_mode, regno_first);
4459 /* If the number of words in the subreg is less than the number
4460 of words in the full register, we have a well-defined partial
4461 set. Otherwise the high bits are undefined.
4463 This is only really applicable to pseudos, since we just took
4464 care of multi-word hard registers. */
4465 if (((GET_MODE_SIZE (outer_mode)
4466 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
4467 < ((GET_MODE_SIZE (inner_mode)
4468 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
4469 not_dead = REGNO_REG_SET_P (pbi->reg_live, regno_first);
4471 reg = SUBREG_REG (reg);
4475 reg = SUBREG_REG (reg);
4482 /* If this set is a MEM, then it kills any aliased writes.
4483 If this set is a REG, then it kills any MEMs which use the reg. */
4484 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4486 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
4488 rtx temp = pbi->mem_set_list;
4489 rtx prev = NULL_RTX;
4494 next = XEXP (temp, 1);
4495 if ((GET_CODE (reg) == MEM
4496 && output_dependence (XEXP (temp, 0), reg))
4497 || (GET_CODE (reg) == REG
4498 && reg_overlap_mentioned_p (reg, XEXP (temp, 0))))
4500 /* Splice this entry out of the list. */
4502 XEXP (prev, 1) = next;
4504 pbi->mem_set_list = next;
4505 free_EXPR_LIST_node (temp);
4513 /* If the memory reference had embedded side effects (autoincrement
4514 address modes. Then we may need to kill some entries on the
4516 if (insn && GET_CODE (reg) == MEM)
4517 invalidate_mems_from_autoinc (pbi, insn);
4519 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
4520 /* ??? With more effort we could track conditional memory life. */
4522 /* We do not know the size of a BLKmode store, so we do not track
4523 them for redundant store elimination. */
4524 && GET_MODE (reg) != BLKmode
4525 /* There are no REG_INC notes for SP, so we can't assume we'll see
4526 everything that invalidates it. To be safe, don't eliminate any
4527 stores though SP; none of them should be redundant anyway. */
4528 && ! reg_mentioned_p (stack_pointer_rtx, reg))
4529 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
4532 if (GET_CODE (reg) == REG
4533 && ! (regno_first == FRAME_POINTER_REGNUM
4534 && (! reload_completed || frame_pointer_needed))
4535 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4536 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
4537 && (! reload_completed || frame_pointer_needed))
4539 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4540 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
4544 int some_was_live = 0, some_was_dead = 0;
4546 for (i = regno_first; i <= regno_last; ++i)
4548 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
4550 SET_REGNO_REG_SET (pbi->local_set, i);
4551 if (code != CLOBBER)
4552 SET_REGNO_REG_SET (pbi->new_set, i);
4554 some_was_live |= needed_regno;
4555 some_was_dead |= ! needed_regno;
4558 #ifdef HAVE_conditional_execution
4559 /* Consider conditional death in deciding that the register needs
4561 if (some_was_live && ! not_dead
4562 /* The stack pointer is never dead. Well, not strictly true,
4563 but it's very difficult to tell from here. Hopefully
4564 combine_stack_adjustments will fix up the most egregious
4566 && regno_first != STACK_POINTER_REGNUM)
4568 for (i = regno_first; i <= regno_last; ++i)
4569 if (! mark_regno_cond_dead (pbi, i, cond))
4574 /* Additional data to record if this is the final pass. */
4575 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
4576 | PROP_DEATH_NOTES | PROP_AUTOINC))
4579 register int blocknum = pbi->bb->index;
4582 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4584 y = pbi->reg_next_use[regno_first];
4586 /* The next use is no longer next, since a store intervenes. */
4587 for (i = regno_first; i <= regno_last; ++i)
4588 pbi->reg_next_use[i] = 0;
4591 if (flags & PROP_REG_INFO)
4593 for (i = regno_first; i <= regno_last; ++i)
4595 /* Count (weighted) references, stores, etc. This counts a
4596 register twice if it is modified, but that is correct. */
4597 REG_N_SETS (i) += 1;
4598 REG_N_REFS (i) += (optimize_size ? 1
4599 : pbi->bb->loop_depth + 1);
4601 /* The insns where a reg is live are normally counted
4602 elsewhere, but we want the count to include the insn
4603 where the reg is set, and the normal counting mechanism
4604 would not count it. */
4605 REG_LIVE_LENGTH (i) += 1;
4608 /* If this is a hard reg, record this function uses the reg. */
4609 if (regno_first < FIRST_PSEUDO_REGISTER)
4611 for (i = regno_first; i <= regno_last; i++)
4612 regs_ever_live[i] = 1;
4616 /* Keep track of which basic blocks each reg appears in. */
4617 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
4618 REG_BASIC_BLOCK (regno_first) = blocknum;
4619 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
4620 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
4624 if (! some_was_dead)
4626 if (flags & PROP_LOG_LINKS)
4628 /* Make a logical link from the next following insn
4629 that uses this register, back to this insn.
4630 The following insns have already been processed.
4632 We don't build a LOG_LINK for hard registers containing
4633 in ASM_OPERANDs. If these registers get replaced,
4634 we might wind up changing the semantics of the insn,
4635 even if reload can make what appear to be valid
4636 assignments later. */
4637 if (y && (BLOCK_NUM (y) == blocknum)
4638 && (regno_first >= FIRST_PSEUDO_REGISTER
4639 || asm_noperands (PATTERN (y)) < 0))
4640 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4645 else if (! some_was_live)
4647 if (flags & PROP_REG_INFO)
4648 REG_N_DEATHS (regno_first) += 1;
4650 if (flags & PROP_DEATH_NOTES)
4652 /* Note that dead stores have already been deleted
4653 when possible. If we get here, we have found a
4654 dead store that cannot be eliminated (because the
4655 same insn does something useful). Indicate this
4656 by marking the reg being set as dying here. */
4658 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4663 if (flags & PROP_DEATH_NOTES)
4665 /* This is a case where we have a multi-word hard register
4666 and some, but not all, of the words of the register are
4667 needed in subsequent insns. Write REG_UNUSED notes
4668 for those parts that were not needed. This case should
4671 for (i = regno_first; i <= regno_last; ++i)
4672 if (! REGNO_REG_SET_P (pbi->reg_live, i))
4674 = alloc_EXPR_LIST (REG_UNUSED,
4675 gen_rtx_REG (reg_raw_mode[i], i),
4681 /* Mark the register as being dead. */
4684 /* The stack pointer is never dead. Well, not strictly true,
4685 but it's very difficult to tell from here. Hopefully
4686 combine_stack_adjustments will fix up the most egregious
4688 && regno_first != STACK_POINTER_REGNUM)
4690 for (i = regno_first; i <= regno_last; ++i)
4691 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
4694 else if (GET_CODE (reg) == REG)
4696 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4697 pbi->reg_next_use[regno_first] = 0;
4700 /* If this is the last pass and this is a SCRATCH, show it will be dying
4701 here and count it. */
4702 else if (GET_CODE (reg) == SCRATCH)
4704 if (flags & PROP_DEATH_NOTES)
4706 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4710 #ifdef HAVE_conditional_execution
4711 /* Mark REGNO conditionally dead.
4712 Return true if the register is now unconditionally dead. */
4715 mark_regno_cond_dead (pbi, regno, cond)
4716 struct propagate_block_info *pbi;
4720 /* If this is a store to a predicate register, the value of the
4721 predicate is changing, we don't know that the predicate as seen
4722 before is the same as that seen after. Flush all dependent
4723 conditions from reg_cond_dead. This will make all such
4724 conditionally live registers unconditionally live. */
4725 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
4726 flush_reg_cond_reg (pbi, regno);
4728 /* If this is an unconditional store, remove any conditional
4729 life that may have existed. */
4730 if (cond == NULL_RTX)
4731 splay_tree_remove (pbi->reg_cond_dead, regno);
4734 splay_tree_node node;
4735 struct reg_cond_life_info *rcli;
4738 /* Otherwise this is a conditional set. Record that fact.
4739 It may have been conditionally used, or there may be a
4740 subsequent set with a complimentary condition. */
4742 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
4745 /* The register was unconditionally live previously.
4746 Record the current condition as the condition under
4747 which it is dead. */
4748 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4749 rcli->condition = alloc_EXPR_LIST (0, cond, NULL_RTX);
4750 splay_tree_insert (pbi->reg_cond_dead, regno,
4751 (splay_tree_value) rcli);
4753 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
4755 /* Not unconditionaly dead. */
4760 /* The register was conditionally live previously.
4761 Add the new condition to the old. */
4762 rcli = (struct reg_cond_life_info *) node->value;
4763 ncond = rcli->condition;
4764 ncond = ior_reg_cond (ncond, cond);
4766 /* If the register is now unconditionally dead,
4767 remove the entry in the splay_tree. */
4768 if (ncond == const1_rtx)
4769 splay_tree_remove (pbi->reg_cond_dead, regno);
4772 rcli->condition = ncond;
4774 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
4776 /* Not unconditionaly dead. */
4785 /* Called from splay_tree_delete for pbi->reg_cond_life. */
4788 free_reg_cond_life_info (value)
4789 splay_tree_value value;
4791 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
4792 free_EXPR_LIST_list (&rcli->condition);
4796 /* Helper function for flush_reg_cond_reg. */
4799 flush_reg_cond_reg_1 (node, data)
4800 splay_tree_node node;
4803 struct reg_cond_life_info *rcli;
4804 int *xdata = (int *) data;
4805 unsigned int regno = xdata[0];
4808 /* Don't need to search if last flushed value was farther on in
4809 the in-order traversal. */
4810 if (xdata[1] >= (int) node->key)
4813 /* Splice out portions of the expression that refer to regno. */
4814 rcli = (struct reg_cond_life_info *) node->value;
4815 c = *(prev = &rcli->condition);
4818 if (regno == REGNO (XEXP (XEXP (c, 0), 0)))
4820 rtx next = XEXP (c, 1);
4821 free_EXPR_LIST_node (c);
4825 c = *(prev = &XEXP (c, 1));
4828 /* If the entire condition is now NULL, signal the node to be removed. */
4829 if (! rcli->condition)
4831 xdata[1] = node->key;
4838 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
4841 flush_reg_cond_reg (pbi, regno)
4842 struct propagate_block_info *pbi;
4849 while (splay_tree_foreach (pbi->reg_cond_dead,
4850 flush_reg_cond_reg_1, pair) == -1)
4851 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
4853 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
4856 /* Logical arithmetic on predicate conditions. IOR, NOT and NAND.
4857 We actually use EXPR_LIST to chain the sub-expressions together
4858 instead of IOR because it's easier to manipulate and we have
4859 the lists.c functions to reuse nodes.
4861 Return a new rtl expression as appropriate. */
4864 ior_reg_cond (old, x)
4867 enum rtx_code x_code;
4871 /* We expect these conditions to be of the form (eq reg 0). */
4872 x_code = GET_CODE (x);
4873 if (GET_RTX_CLASS (x_code) != '<'
4874 || GET_CODE (x_reg = XEXP (x, 0)) != REG
4875 || XEXP (x, 1) != const0_rtx)
4878 /* Search the expression for an existing sub-expression of X_REG. */
4879 for (c = old; c; c = XEXP (c, 1))
4881 rtx y = XEXP (c, 0);
4882 if (REGNO (XEXP (y, 0)) == REGNO (x_reg))
4884 /* If we find X already present in OLD, we need do nothing. */
4885 if (GET_CODE (y) == x_code)
4888 /* If we find X being a compliment of a condition in OLD,
4889 then the entire condition is true. */
4890 if (GET_CODE (y) == reverse_condition (x_code))
4895 /* Otherwise just add to the chain. */
4896 return alloc_EXPR_LIST (0, x, old);
4903 enum rtx_code x_code;
4906 /* We expect these conditions to be of the form (eq reg 0). */
4907 x_code = GET_CODE (x);
4908 if (GET_RTX_CLASS (x_code) != '<'
4909 || GET_CODE (x_reg = XEXP (x, 0)) != REG
4910 || XEXP (x, 1) != const0_rtx)
4913 return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code),
4914 VOIDmode, x_reg, const0_rtx),
4919 nand_reg_cond (old, x)
4922 enum rtx_code x_code;
4926 /* We expect these conditions to be of the form (eq reg 0). */
4927 x_code = GET_CODE (x);
4928 if (GET_RTX_CLASS (x_code) != '<'
4929 || GET_CODE (x_reg = XEXP (x, 0)) != REG
4930 || XEXP (x, 1) != const0_rtx)
4933 /* Search the expression for an existing sub-expression of X_REG. */
4935 for (c = *(prev = &old); c; c = *(prev = &XEXP (c, 1)))
4937 rtx y = XEXP (c, 0);
4938 if (REGNO (XEXP (y, 0)) == REGNO (x_reg))
4940 /* If we find X already present in OLD, then we need to
4942 if (GET_CODE (y) == x_code)
4944 *prev = XEXP (c, 1);
4945 free_EXPR_LIST_node (c);
4946 return old ? old : const0_rtx;
4949 /* If we find X being a compliment of a condition in OLD,
4950 then we need do nothing. */
4951 if (GET_CODE (y) == reverse_condition (x_code))
4956 /* Otherwise, by implication, the register in question is now live for
4957 the inverse of the condition X. */
4958 return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code),
4959 VOIDmode, x_reg, const0_rtx),
4962 #endif /* HAVE_conditional_execution */
4966 /* Try to substitute the auto-inc expression INC as the address inside
4967 MEM which occurs in INSN. Currently, the address of MEM is an expression
4968 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
4969 that has a single set whose source is a PLUS of INCR_REG and something
4973 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
4974 struct propagate_block_info *pbi;
4975 rtx inc, insn, mem, incr, incr_reg;
4977 int regno = REGNO (incr_reg);
4978 rtx set = single_set (incr);
4979 rtx q = SET_DEST (set);
4980 rtx y = SET_SRC (set);
4981 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
4983 /* Make sure this reg appears only once in this insn. */
4984 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
4987 if (dead_or_set_p (incr, incr_reg)
4988 /* Mustn't autoinc an eliminable register. */
4989 && (regno >= FIRST_PSEUDO_REGISTER
4990 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
4992 /* This is the simple case. Try to make the auto-inc. If
4993 we can't, we are done. Otherwise, we will do any
4994 needed updates below. */
4995 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
4998 else if (GET_CODE (q) == REG
4999 /* PREV_INSN used here to check the semi-open interval
5001 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5002 /* We must also check for sets of q as q may be
5003 a call clobbered hard register and there may
5004 be a call between PREV_INSN (insn) and incr. */
5005 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5007 /* We have *p followed sometime later by q = p+size.
5008 Both p and q must be live afterward,
5009 and q is not used between INSN and its assignment.
5010 Change it to q = p, ...*q..., q = q+size.
5011 Then fall into the usual case. */
5015 emit_move_insn (q, incr_reg);
5016 insns = get_insns ();
5019 if (basic_block_for_insn)
5020 for (temp = insns; temp; temp = NEXT_INSN (temp))
5021 set_block_for_insn (temp, pbi->bb);
5023 /* If we can't make the auto-inc, or can't make the
5024 replacement into Y, exit. There's no point in making
5025 the change below if we can't do the auto-inc and doing
5026 so is not correct in the pre-inc case. */
5029 validate_change (insn, &XEXP (mem, 0), inc, 1);
5030 validate_change (incr, &XEXP (y, opnum), q, 1);
5031 if (! apply_change_group ())
5034 /* We now know we'll be doing this change, so emit the
5035 new insn(s) and do the updates. */
5036 emit_insns_before (insns, insn);
5038 if (pbi->bb->head == insn)
5039 pbi->bb->head = insns;
5041 /* INCR will become a NOTE and INSN won't contain a
5042 use of INCR_REG. If a use of INCR_REG was just placed in
5043 the insn before INSN, make that the next use.
5044 Otherwise, invalidate it. */
5045 if (GET_CODE (PREV_INSN (insn)) == INSN
5046 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
5047 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
5048 pbi->reg_next_use[regno] = PREV_INSN (insn);
5050 pbi->reg_next_use[regno] = 0;
5055 /* REGNO is now used in INCR which is below INSN, but
5056 it previously wasn't live here. If we don't mark
5057 it as live, we'll put a REG_DEAD note for it
5058 on this insn, which is incorrect. */
5059 SET_REGNO_REG_SET (pbi->reg_live, regno);
5061 /* If there are any calls between INSN and INCR, show
5062 that REGNO now crosses them. */
5063 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
5064 if (GET_CODE (temp) == CALL_INSN)
5065 REG_N_CALLS_CROSSED (regno)++;
5070 /* If we haven't returned, it means we were able to make the
5071 auto-inc, so update the status. First, record that this insn
5072 has an implicit side effect. */
5074 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
5076 /* Modify the old increment-insn to simply copy
5077 the already-incremented value of our register. */
5078 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
5081 /* If that makes it a no-op (copying the register into itself) delete
5082 it so it won't appear to be a "use" and a "set" of this
5084 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
5086 /* If the original source was dead, it's dead now. */
5089 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
5091 remove_note (incr, note);
5092 if (XEXP (note, 0) != incr_reg)
5093 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
5096 PUT_CODE (incr, NOTE);
5097 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
5098 NOTE_SOURCE_FILE (incr) = 0;
5101 if (regno >= FIRST_PSEUDO_REGISTER)
5103 /* Count an extra reference to the reg. When a reg is
5104 incremented, spilling it is worse, so we want to make
5105 that less likely. */
5106 REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5108 /* Count the increment as a setting of the register,
5109 even though it isn't a SET in rtl. */
5110 REG_N_SETS (regno)++;
5114 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
5118 find_auto_inc (pbi, x, insn)
5119 struct propagate_block_info *pbi;
5123 rtx addr = XEXP (x, 0);
5124 HOST_WIDE_INT offset = 0;
5125 rtx set, y, incr, inc_val;
5127 int size = GET_MODE_SIZE (GET_MODE (x));
5129 if (GET_CODE (insn) == JUMP_INSN)
5132 /* Here we detect use of an index register which might be good for
5133 postincrement, postdecrement, preincrement, or predecrement. */
5135 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
5136 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
5138 if (GET_CODE (addr) != REG)
5141 regno = REGNO (addr);
5143 /* Is the next use an increment that might make auto-increment? */
5144 incr = pbi->reg_next_use[regno];
5145 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
5147 set = single_set (incr);
5148 if (set == 0 || GET_CODE (set) != SET)
5152 if (GET_CODE (y) != PLUS)
5155 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
5156 inc_val = XEXP (y, 1);
5157 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
5158 inc_val = XEXP (y, 0);
5162 if (GET_CODE (inc_val) == CONST_INT)
5164 if (HAVE_POST_INCREMENT
5165 && (INTVAL (inc_val) == size && offset == 0))
5166 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
5168 else if (HAVE_POST_DECREMENT
5169 && (INTVAL (inc_val) == -size && offset == 0))
5170 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
5172 else if (HAVE_PRE_INCREMENT
5173 && (INTVAL (inc_val) == size && offset == size))
5174 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
5176 else if (HAVE_PRE_DECREMENT
5177 && (INTVAL (inc_val) == -size && offset == -size))
5178 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
5180 else if (HAVE_POST_MODIFY_DISP && offset == 0)
5181 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5182 gen_rtx_PLUS (Pmode,
5185 insn, x, incr, addr);
5187 else if (GET_CODE (inc_val) == REG
5188 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
5192 if (HAVE_POST_MODIFY_REG && offset == 0)
5193 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5194 gen_rtx_PLUS (Pmode,
5197 insn, x, incr, addr);
5201 #endif /* AUTO_INC_DEC */
5204 mark_used_reg (pbi, reg, cond, insn)
5205 struct propagate_block_info *pbi;
5207 rtx cond ATTRIBUTE_UNUSED;
5210 int regno = REGNO (reg);
5211 int some_was_live = REGNO_REG_SET_P (pbi->reg_live, regno);
5212 int some_was_dead = ! some_was_live;
5216 /* A hard reg in a wide mode may really be multiple registers.
5217 If so, mark all of them just like the first. */
5218 if (regno < FIRST_PSEUDO_REGISTER)
5220 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5223 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, regno + n);
5224 some_was_live |= needed_regno;
5225 some_was_dead |= ! needed_regno;
5229 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5231 /* Record where each reg is used, so when the reg is set we know
5232 the next insn that uses it. */
5233 pbi->reg_next_use[regno] = insn;
5236 if (pbi->flags & PROP_REG_INFO)
5238 if (regno < FIRST_PSEUDO_REGISTER)
5240 /* If this is a register we are going to try to eliminate,
5241 don't mark it live here. If we are successful in
5242 eliminating it, it need not be live unless it is used for
5243 pseudos, in which case it will have been set live when it
5244 was allocated to the pseudos. If the register will not
5245 be eliminated, reload will set it live at that point.
5247 Otherwise, record that this function uses this register. */
5248 /* ??? The PPC backend tries to "eliminate" on the pic
5249 register to itself. This should be fixed. In the mean
5250 time, hack around it. */
5252 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno)
5253 && (regno == FRAME_POINTER_REGNUM
5254 || regno == ARG_POINTER_REGNUM)))
5256 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5258 regs_ever_live[regno + --n] = 1;
5264 /* Keep track of which basic block each reg appears in. */
5266 register int blocknum = pbi->bb->index;
5267 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
5268 REG_BASIC_BLOCK (regno) = blocknum;
5269 else if (REG_BASIC_BLOCK (regno) != blocknum)
5270 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
5272 /* Count (weighted) number of uses of each reg. */
5273 REG_N_REFS (regno) += (optimize_size ? 1
5274 : pbi->bb->loop_depth + 1);
5278 /* Find out if any of the register was set this insn. */
5279 some_not_set = ! REGNO_REG_SET_P (pbi->new_set, regno);
5280 if (regno < FIRST_PSEUDO_REGISTER)
5282 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5284 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, regno + n);
5287 /* Record and count the insns in which a reg dies. If it is used in
5288 this insn and was dead below the insn then it dies in this insn.
5289 If it was set in this insn, we do not make a REG_DEAD note;
5290 likewise if we already made such a note. */
5291 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
5295 /* Check for the case where the register dying partially
5296 overlaps the register set by this insn. */
5297 if (regno < FIRST_PSEUDO_REGISTER
5298 && HARD_REGNO_NREGS (regno, GET_MODE (reg)) > 1)
5300 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5302 some_was_live |= REGNO_REG_SET_P (pbi->new_set, regno + n);
5305 /* If none of the words in X is needed, make a REG_DEAD note.
5306 Otherwise, we must make partial REG_DEAD notes. */
5307 if (! some_was_live)
5309 if ((pbi->flags & PROP_DEATH_NOTES)
5310 && ! find_regno_note (insn, REG_DEAD, regno))
5312 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
5314 if (pbi->flags & PROP_REG_INFO)
5315 REG_N_DEATHS (regno)++;
5319 /* Don't make a REG_DEAD note for a part of a register
5320 that is set in the insn. */
5322 n = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
5323 for (; n >= regno; n--)
5324 if (! REGNO_REG_SET_P (pbi->reg_live, n)
5325 && ! dead_or_set_regno_p (insn, n))
5327 = alloc_EXPR_LIST (REG_DEAD,
5328 gen_rtx_REG (reg_raw_mode[n], n),
5333 SET_REGNO_REG_SET (pbi->reg_live, regno);
5334 if (regno < FIRST_PSEUDO_REGISTER)
5336 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5338 SET_REGNO_REG_SET (pbi->reg_live, regno + n);
5341 #ifdef HAVE_conditional_execution
5342 /* If this is a conditional use, record that fact. If it is later
5343 conditionally set, we'll know to kill the register. */
5344 if (cond != NULL_RTX)
5346 splay_tree_node node;
5347 struct reg_cond_life_info *rcli;
5352 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5355 /* The register was unconditionally live previously.
5356 No need to do anything. */
5360 /* The register was conditionally live previously.
5361 Subtract the new life cond from the old death cond. */
5362 rcli = (struct reg_cond_life_info *) node->value;
5363 ncond = rcli->condition;
5364 ncond = nand_reg_cond (ncond, cond);
5366 /* If the register is now unconditionally live, remove the
5367 entry in the splay_tree. */
5368 if (ncond == const0_rtx)
5370 rcli->condition = NULL_RTX;
5371 splay_tree_remove (pbi->reg_cond_dead, regno);
5375 rcli->condition = ncond;
5376 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5382 /* The register was not previously live at all. Record
5383 the condition under which it is still dead. */
5384 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5385 rcli->condition = not_reg_cond (cond);
5386 splay_tree_insert (pbi->reg_cond_dead, regno,
5387 (splay_tree_value) rcli);
5389 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5392 else if (some_was_live)
5394 splay_tree_node node;
5395 struct reg_cond_life_info *rcli;
5397 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5400 /* The register was conditionally live previously, but is now
5401 unconditionally so. Remove it from the conditionally dead
5402 list, so that a conditional set won't cause us to think
5404 rcli = (struct reg_cond_life_info *) node->value;
5405 rcli->condition = NULL_RTX;
5406 splay_tree_remove (pbi->reg_cond_dead, regno);
5413 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5414 This is done assuming the registers needed from X are those that
5415 have 1-bits in PBI->REG_LIVE.
5417 INSN is the containing instruction. If INSN is dead, this function
5421 mark_used_regs (pbi, x, cond, insn)
5422 struct propagate_block_info *pbi;
5425 register RTX_CODE code;
5427 int flags = pbi->flags;
5430 code = GET_CODE (x);
5450 /* If we are clobbering a MEM, mark any registers inside the address
5452 if (GET_CODE (XEXP (x, 0)) == MEM)
5453 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
5457 /* Don't bother watching stores to mems if this is not the
5458 final pass. We'll not be deleting dead stores this round. */
5459 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5461 /* Invalidate the data for the last MEM stored, but only if MEM is
5462 something that can be stored into. */
5463 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
5464 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
5465 /* Needn't clear the memory set list. */
5469 rtx temp = pbi->mem_set_list;
5470 rtx prev = NULL_RTX;
5475 next = XEXP (temp, 1);
5476 if (anti_dependence (XEXP (temp, 0), x))
5478 /* Splice temp out of the list. */
5480 XEXP (prev, 1) = next;
5482 pbi->mem_set_list = next;
5483 free_EXPR_LIST_node (temp);
5491 /* If the memory reference had embedded side effects (autoincrement
5492 address modes. Then we may need to kill some entries on the
5495 invalidate_mems_from_autoinc (pbi, insn);
5499 if (flags & PROP_AUTOINC)
5500 find_auto_inc (pbi, x, insn);
5505 #ifdef CLASS_CANNOT_CHANGE_MODE
5506 if (GET_CODE (SUBREG_REG (x)) == REG
5507 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
5508 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
5509 GET_MODE (SUBREG_REG (x))))
5510 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
5513 /* While we're here, optimize this case. */
5515 if (GET_CODE (x) != REG)
5520 /* See a register other than being set => mark it as needed. */
5521 mark_used_reg (pbi, x, cond, insn);
5526 register rtx testreg = SET_DEST (x);
5529 /* If storing into MEM, don't show it as being used. But do
5530 show the address as being used. */
5531 if (GET_CODE (testreg) == MEM)
5534 if (flags & PROP_AUTOINC)
5535 find_auto_inc (pbi, testreg, insn);
5537 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
5538 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5542 /* Storing in STRICT_LOW_PART is like storing in a reg
5543 in that this SET might be dead, so ignore it in TESTREG.
5544 but in some other ways it is like using the reg.
5546 Storing in a SUBREG or a bit field is like storing the entire
5547 register in that if the register's value is not used
5548 then this SET is not needed. */
5549 while (GET_CODE (testreg) == STRICT_LOW_PART
5550 || GET_CODE (testreg) == ZERO_EXTRACT
5551 || GET_CODE (testreg) == SIGN_EXTRACT
5552 || GET_CODE (testreg) == SUBREG)
5554 #ifdef CLASS_CANNOT_CHANGE_MODE
5555 if (GET_CODE (testreg) == SUBREG
5556 && GET_CODE (SUBREG_REG (testreg)) == REG
5557 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
5558 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
5559 GET_MODE (testreg)))
5560 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
5563 /* Modifying a single register in an alternate mode
5564 does not use any of the old value. But these other
5565 ways of storing in a register do use the old value. */
5566 if (GET_CODE (testreg) == SUBREG
5567 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5572 testreg = XEXP (testreg, 0);
5575 /* If this is a store into a register, recursively scan the
5576 value being stored. */
5578 if ((GET_CODE (testreg) == PARALLEL
5579 && GET_MODE (testreg) == BLKmode)
5580 || (GET_CODE (testreg) == REG
5581 && (regno = REGNO (testreg),
5582 ! (regno == FRAME_POINTER_REGNUM
5583 && (! reload_completed || frame_pointer_needed)))
5584 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5585 && ! (regno == HARD_FRAME_POINTER_REGNUM
5586 && (! reload_completed || frame_pointer_needed))
5588 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5589 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5594 mark_used_regs (pbi, SET_DEST (x), cond, insn);
5595 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5602 case UNSPEC_VOLATILE:
5606 /* Traditional and volatile asm instructions must be considered to use
5607 and clobber all hard registers, all pseudo-registers and all of
5608 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
5610 Consider for instance a volatile asm that changes the fpu rounding
5611 mode. An insn should not be moved across this even if it only uses
5612 pseudo-regs because it might give an incorrectly rounded result.
5614 ?!? Unfortunately, marking all hard registers as live causes massive
5615 problems for the register allocator and marking all pseudos as live
5616 creates mountains of uninitialized variable warnings.
5618 So for now, just clear the memory set list and mark any regs
5619 we can find in ASM_OPERANDS as used. */
5620 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
5621 free_EXPR_LIST_list (&pbi->mem_set_list);
5623 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
5624 We can not just fall through here since then we would be confused
5625 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
5626 traditional asms unlike their normal usage. */
5627 if (code == ASM_OPERANDS)
5631 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
5632 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
5638 if (cond != NULL_RTX)
5641 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
5643 cond = COND_EXEC_TEST (x);
5644 x = COND_EXEC_CODE (x);
5648 /* We _do_not_ want to scan operands of phi nodes. Operands of
5649 a phi function are evaluated only when control reaches this
5650 block along a particular edge. Therefore, regs that appear
5651 as arguments to phi should not be added to the global live at
5659 /* Recursively scan the operands of this expression. */
5662 register const char *fmt = GET_RTX_FORMAT (code);
5665 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5669 /* Tail recursive case: save a function call level. */
5675 mark_used_regs (pbi, XEXP (x, i), cond, insn);
5677 else if (fmt[i] == 'E')
5680 for (j = 0; j < XVECLEN (x, i); j++)
5681 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
5690 try_pre_increment_1 (pbi, insn)
5691 struct propagate_block_info *pbi;
5694 /* Find the next use of this reg. If in same basic block,
5695 make it do pre-increment or pre-decrement if appropriate. */
5696 rtx x = single_set (insn);
5697 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
5698 * INTVAL (XEXP (SET_SRC (x), 1)));
5699 int regno = REGNO (SET_DEST (x));
5700 rtx y = pbi->reg_next_use[regno];
5702 && SET_DEST (x) != stack_pointer_rtx
5703 && BLOCK_NUM (y) == BLOCK_NUM (insn)
5704 /* Don't do this if the reg dies, or gets set in y; a standard addressing
5705 mode would be better. */
5706 && ! dead_or_set_p (y, SET_DEST (x))
5707 && try_pre_increment (y, SET_DEST (x), amount))
5709 /* We have found a suitable auto-increment
5710 and already changed insn Y to do it.
5711 So flush this increment-instruction. */
5712 PUT_CODE (insn, NOTE);
5713 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
5714 NOTE_SOURCE_FILE (insn) = 0;
5715 /* Count a reference to this reg for the increment
5716 insn we are deleting. When a reg is incremented.
5717 spilling it is worse, so we want to make that
5719 if (regno >= FIRST_PSEUDO_REGISTER)
5721 REG_N_REFS (regno) += (optimize_size ? 1
5722 : pbi->bb->loop_depth + 1);
5723 REG_N_SETS (regno)++;
5730 /* Try to change INSN so that it does pre-increment or pre-decrement
5731 addressing on register REG in order to add AMOUNT to REG.
5732 AMOUNT is negative for pre-decrement.
5733 Returns 1 if the change could be made.
5734 This checks all about the validity of the result of modifying INSN. */
5737 try_pre_increment (insn, reg, amount)
5739 HOST_WIDE_INT amount;
5743 /* Nonzero if we can try to make a pre-increment or pre-decrement.
5744 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
5746 /* Nonzero if we can try to make a post-increment or post-decrement.
5747 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
5748 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
5749 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
5752 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
5755 /* From the sign of increment, see which possibilities are conceivable
5756 on this target machine. */
5757 if (HAVE_PRE_INCREMENT && amount > 0)
5759 if (HAVE_POST_INCREMENT && amount > 0)
5762 if (HAVE_PRE_DECREMENT && amount < 0)
5764 if (HAVE_POST_DECREMENT && amount < 0)
5767 if (! (pre_ok || post_ok))
5770 /* It is not safe to add a side effect to a jump insn
5771 because if the incremented register is spilled and must be reloaded
5772 there would be no way to store the incremented value back in memory. */
5774 if (GET_CODE (insn) == JUMP_INSN)
5779 use = find_use_as_address (PATTERN (insn), reg, 0);
5780 if (post_ok && (use == 0 || use == (rtx) 1))
5782 use = find_use_as_address (PATTERN (insn), reg, -amount);
5786 if (use == 0 || use == (rtx) 1)
5789 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
5792 /* See if this combination of instruction and addressing mode exists. */
5793 if (! validate_change (insn, &XEXP (use, 0),
5794 gen_rtx_fmt_e (amount > 0
5795 ? (do_post ? POST_INC : PRE_INC)
5796 : (do_post ? POST_DEC : PRE_DEC),
5800 /* Record that this insn now has an implicit side effect on X. */
5801 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
5805 #endif /* AUTO_INC_DEC */
5807 /* Find the place in the rtx X where REG is used as a memory address.
5808 Return the MEM rtx that so uses it.
5809 If PLUSCONST is nonzero, search instead for a memory address equivalent to
5810 (plus REG (const_int PLUSCONST)).
5812 If such an address does not appear, return 0.
5813 If REG appears more than once, or is used other than in such an address,
5817 find_use_as_address (x, reg, plusconst)
5820 HOST_WIDE_INT plusconst;
5822 enum rtx_code code = GET_CODE (x);
5823 const char *fmt = GET_RTX_FORMAT (code);
5825 register rtx value = 0;
5828 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
5831 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
5832 && XEXP (XEXP (x, 0), 0) == reg
5833 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
5834 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
5837 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
5839 /* If REG occurs inside a MEM used in a bit-field reference,
5840 that is unacceptable. */
5841 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
5842 return (rtx) (HOST_WIDE_INT) 1;
5846 return (rtx) (HOST_WIDE_INT) 1;
5848 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
5852 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
5856 return (rtx) (HOST_WIDE_INT) 1;
5858 else if (fmt[i] == 'E')
5861 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5863 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
5867 return (rtx) (HOST_WIDE_INT) 1;
5875 /* Write information about registers and basic blocks into FILE.
5876 This is part of making a debugging dump. */
5879 dump_regset (r, outf)
5886 fputs (" (nil)", outf);
5890 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
5892 fprintf (outf, " %d", i);
5893 if (i < FIRST_PSEUDO_REGISTER)
5894 fprintf (outf, " [%s]",
5903 dump_regset (r, stderr);
5904 putc ('\n', stderr);
5908 dump_flow_info (file)
5912 static const char * const reg_class_names[] = REG_CLASS_NAMES;
5914 fprintf (file, "%d registers.\n", max_regno);
5915 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
5918 enum reg_class class, altclass;
5919 fprintf (file, "\nRegister %d used %d times across %d insns",
5920 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
5921 if (REG_BASIC_BLOCK (i) >= 0)
5922 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
5924 fprintf (file, "; set %d time%s", REG_N_SETS (i),
5925 (REG_N_SETS (i) == 1) ? "" : "s");
5926 if (REG_USERVAR_P (regno_reg_rtx[i]))
5927 fprintf (file, "; user var");
5928 if (REG_N_DEATHS (i) != 1)
5929 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
5930 if (REG_N_CALLS_CROSSED (i) == 1)
5931 fprintf (file, "; crosses 1 call");
5932 else if (REG_N_CALLS_CROSSED (i))
5933 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
5934 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
5935 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
5936 class = reg_preferred_class (i);
5937 altclass = reg_alternate_class (i);
5938 if (class != GENERAL_REGS || altclass != ALL_REGS)
5940 if (altclass == ALL_REGS || class == ALL_REGS)
5941 fprintf (file, "; pref %s", reg_class_names[(int) class]);
5942 else if (altclass == NO_REGS)
5943 fprintf (file, "; %s or none", reg_class_names[(int) class]);
5945 fprintf (file, "; pref %s, else %s",
5946 reg_class_names[(int) class],
5947 reg_class_names[(int) altclass]);
5949 if (REGNO_POINTER_FLAG (i))
5950 fprintf (file, "; pointer");
5951 fprintf (file, ".\n");
5954 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
5955 for (i = 0; i < n_basic_blocks; i++)
5957 register basic_block bb = BASIC_BLOCK (i);
5960 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
5961 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count);
5963 fprintf (file, "Predecessors: ");
5964 for (e = bb->pred; e; e = e->pred_next)
5965 dump_edge_info (file, e, 0);
5967 fprintf (file, "\nSuccessors: ");
5968 for (e = bb->succ; e; e = e->succ_next)
5969 dump_edge_info (file, e, 1);
5971 fprintf (file, "\nRegisters live at start:");
5972 dump_regset (bb->global_live_at_start, file);
5974 fprintf (file, "\nRegisters live at end:");
5975 dump_regset (bb->global_live_at_end, file);
5986 dump_flow_info (stderr);
5990 dump_edge_info (file, e, do_succ)
5995 basic_block side = (do_succ ? e->dest : e->src);
5997 if (side == ENTRY_BLOCK_PTR)
5998 fputs (" ENTRY", file);
5999 else if (side == EXIT_BLOCK_PTR)
6000 fputs (" EXIT", file);
6002 fprintf (file, " %d", side->index);
6005 fprintf (file, " count:%d", e->count);
6009 static const char * const bitnames[] = {
6010 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6013 int i, flags = e->flags;
6017 for (i = 0; flags; i++)
6018 if (flags & (1 << i))
6024 if (i < (int) ARRAY_SIZE (bitnames))
6025 fputs (bitnames[i], file);
6027 fprintf (file, "%d", i);
6034 /* Print out one basic block with live information at start and end. */
6045 fprintf (outf, ";; Basic block %d, loop depth %d, count %d",
6046 bb->index, bb->loop_depth, bb->count);
6047 if (bb->eh_beg != -1 || bb->eh_end != -1)
6048 fprintf (outf, ", eh regions %d/%d", bb->eh_beg, bb->eh_end);
6051 fputs (";; Predecessors: ", outf);
6052 for (e = bb->pred; e; e = e->pred_next)
6053 dump_edge_info (outf, e, 0);
6056 fputs (";; Registers live at start:", outf);
6057 dump_regset (bb->global_live_at_start, outf);
6060 for (insn = bb->head, last = NEXT_INSN (bb->end);
6062 insn = NEXT_INSN (insn))
6063 print_rtl_single (outf, insn);
6065 fputs (";; Registers live at end:", outf);
6066 dump_regset (bb->global_live_at_end, outf);
6069 fputs (";; Successors: ", outf);
6070 for (e = bb->succ; e; e = e->succ_next)
6071 dump_edge_info (outf, e, 1);
6079 dump_bb (bb, stderr);
6086 dump_bb (BASIC_BLOCK (n), stderr);
6089 /* Like print_rtl, but also print out live information for the start of each
6093 print_rtl_with_bb (outf, rtx_first)
6097 register rtx tmp_rtx;
6100 fprintf (outf, "(nil)\n");
6104 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
6105 int max_uid = get_max_uid ();
6106 basic_block *start = (basic_block *)
6107 xcalloc (max_uid, sizeof (basic_block));
6108 basic_block *end = (basic_block *)
6109 xcalloc (max_uid, sizeof (basic_block));
6110 enum bb_state *in_bb_p = (enum bb_state *)
6111 xcalloc (max_uid, sizeof (enum bb_state));
6113 for (i = n_basic_blocks - 1; i >= 0; i--)
6115 basic_block bb = BASIC_BLOCK (i);
6118 start[INSN_UID (bb->head)] = bb;
6119 end[INSN_UID (bb->end)] = bb;
6120 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
6122 enum bb_state state = IN_MULTIPLE_BB;
6123 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
6125 in_bb_p[INSN_UID (x)] = state;
6132 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
6137 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
6139 fprintf (outf, ";; Start of basic block %d, registers live:",
6141 dump_regset (bb->global_live_at_start, outf);
6145 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
6146 && GET_CODE (tmp_rtx) != NOTE
6147 && GET_CODE (tmp_rtx) != BARRIER)
6148 fprintf (outf, ";; Insn is not within a basic block\n");
6149 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
6150 fprintf (outf, ";; Insn is in multiple basic blocks\n");
6152 did_output = print_rtl_single (outf, tmp_rtx);
6154 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
6156 fprintf (outf, ";; End of basic block %d, registers live:\n",
6158 dump_regset (bb->global_live_at_end, outf);
6171 if (current_function_epilogue_delay_list != 0)
6173 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
6174 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
6175 tmp_rtx = XEXP (tmp_rtx, 1))
6176 print_rtl_single (outf, XEXP (tmp_rtx, 0));
6180 /* Compute dominator relationships using new flow graph structures. */
6183 compute_flow_dominators (dominators, post_dominators)
6184 sbitmap *dominators;
6185 sbitmap *post_dominators;
6188 sbitmap *temp_bitmap;
6190 basic_block *worklist, *workend, *qin, *qout;
6193 /* Allocate a worklist array/queue. Entries are only added to the
6194 list if they were not already on the list. So the size is
6195 bounded by the number of basic blocks. */
6196 worklist = (basic_block *) xmalloc (sizeof (basic_block) * n_basic_blocks);
6197 workend = &worklist[n_basic_blocks];
6199 temp_bitmap = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
6200 sbitmap_vector_zero (temp_bitmap, n_basic_blocks);
6204 /* The optimistic setting of dominators requires us to put every
6205 block on the work list initially. */
6206 qin = qout = worklist;
6207 for (bb = 0; bb < n_basic_blocks; bb++)
6209 *qin++ = BASIC_BLOCK (bb);
6210 BASIC_BLOCK (bb)->aux = BASIC_BLOCK (bb);
6212 qlen = n_basic_blocks;
6215 /* We want a maximal solution, so initially assume everything dominates
6217 sbitmap_vector_ones (dominators, n_basic_blocks);
6219 /* Mark successors of the entry block so we can identify them below. */
6220 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6221 e->dest->aux = ENTRY_BLOCK_PTR;
6223 /* Iterate until the worklist is empty. */
6226 /* Take the first entry off the worklist. */
6227 basic_block b = *qout++;
6228 if (qout >= workend)
6234 /* Compute the intersection of the dominators of all the
6237 If one of the predecessor blocks is the ENTRY block, then the
6238 intersection of the dominators of the predecessor blocks is
6239 defined as the null set. We can identify such blocks by the
6240 special value in the AUX field in the block structure. */
6241 if (b->aux == ENTRY_BLOCK_PTR)
6243 /* Do not clear the aux field for blocks which are
6244 successors of the ENTRY block. That way we never add
6245 them to the worklist again.
6247 The intersect of dominators of the preds of this block is
6248 defined as the null set. */
6249 sbitmap_zero (temp_bitmap[bb]);
6253 /* Clear the aux field of this block so it can be added to
6254 the worklist again if necessary. */
6256 sbitmap_intersection_of_preds (temp_bitmap[bb], dominators, bb);
6259 /* Make sure each block always dominates itself. */
6260 SET_BIT (temp_bitmap[bb], bb);
6262 /* If the out state of this block changed, then we need to
6263 add the successors of this block to the worklist if they
6264 are not already on the worklist. */
6265 if (sbitmap_a_and_b (dominators[bb], dominators[bb], temp_bitmap[bb]))
6267 for (e = b->succ; e; e = e->succ_next)
6269 if (!e->dest->aux && e->dest != EXIT_BLOCK_PTR)
6283 if (post_dominators)
6285 /* The optimistic setting of dominators requires us to put every
6286 block on the work list initially. */
6287 qin = qout = worklist;
6288 for (bb = 0; bb < n_basic_blocks; bb++)
6290 *qin++ = BASIC_BLOCK (bb);
6291 BASIC_BLOCK (bb)->aux = BASIC_BLOCK (bb);
6293 qlen = n_basic_blocks;
6296 /* We want a maximal solution, so initially assume everything post
6297 dominates everything else. */
6298 sbitmap_vector_ones (post_dominators, n_basic_blocks);
6300 /* Mark predecessors of the exit block so we can identify them below. */
6301 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
6302 e->src->aux = EXIT_BLOCK_PTR;
6304 /* Iterate until the worklist is empty. */
6307 /* Take the first entry off the worklist. */
6308 basic_block b = *qout++;
6309 if (qout >= workend)
6315 /* Compute the intersection of the post dominators of all the
6318 If one of the successor blocks is the EXIT block, then the
6319 intersection of the dominators of the successor blocks is
6320 defined as the null set. We can identify such blocks by the
6321 special value in the AUX field in the block structure. */
6322 if (b->aux == EXIT_BLOCK_PTR)
6324 /* Do not clear the aux field for blocks which are
6325 predecessors of the EXIT block. That way we we never
6326 add them to the worklist again.
6328 The intersect of dominators of the succs of this block is
6329 defined as the null set. */
6330 sbitmap_zero (temp_bitmap[bb]);
6334 /* Clear the aux field of this block so it can be added to
6335 the worklist again if necessary. */
6337 sbitmap_intersection_of_succs (temp_bitmap[bb],
6338 post_dominators, bb);
6341 /* Make sure each block always post dominates itself. */
6342 SET_BIT (temp_bitmap[bb], bb);
6344 /* If the out state of this block changed, then we need to
6345 add the successors of this block to the worklist if they
6346 are not already on the worklist. */
6347 if (sbitmap_a_and_b (post_dominators[bb],
6348 post_dominators[bb],
6351 for (e = b->pred; e; e = e->pred_next)
6353 if (!e->src->aux && e->src != ENTRY_BLOCK_PTR)
6371 /* Given DOMINATORS, compute the immediate dominators into IDOM. If a
6372 block dominates only itself, its entry remains as INVALID_BLOCK. */
6375 compute_immediate_dominators (idom, dominators)
6377 sbitmap *dominators;
6382 tmp = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
6384 /* Begin with tmp(n) = dom(n) - { n }. */
6385 for (b = n_basic_blocks; --b >= 0;)
6387 sbitmap_copy (tmp[b], dominators[b]);
6388 RESET_BIT (tmp[b], b);
6391 /* Subtract out all of our dominator's dominators. */
6392 for (b = n_basic_blocks; --b >= 0;)
6394 sbitmap tmp_b = tmp[b];
6397 for (s = n_basic_blocks; --s >= 0;)
6398 if (TEST_BIT (tmp_b, s))
6399 sbitmap_difference (tmp_b, tmp_b, tmp[s]);
6402 /* Find the one bit set in the bitmap and put it in the output array. */
6403 for (b = n_basic_blocks; --b >= 0;)
6406 EXECUTE_IF_SET_IN_SBITMAP (tmp[b], 0, t, { idom[b] = t; });
6409 sbitmap_vector_free (tmp);
6412 /* Given POSTDOMINATORS, compute the immediate postdominators into
6413 IDOM. If a block is only dominated by itself, its entry remains as
6417 compute_immediate_postdominators (idom, postdominators)
6419 sbitmap *postdominators;
6421 compute_immediate_dominators (idom, postdominators);
6424 /* Recompute register set/reference counts immediately prior to register
6427 This avoids problems with set/reference counts changing to/from values
6428 which have special meanings to the register allocators.
6430 Additionally, the reference counts are the primary component used by the
6431 register allocators to prioritize pseudos for allocation to hard regs.
6432 More accurate reference counts generally lead to better register allocation.
6434 F is the first insn to be scanned.
6436 LOOP_STEP denotes how much loop_depth should be incremented per
6437 loop nesting level in order to increase the ref count more for
6438 references in a loop.
6440 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6441 possibly other information which is used by the register allocators. */
6444 recompute_reg_usage (f, loop_step)
6445 rtx f ATTRIBUTE_UNUSED;
6446 int loop_step ATTRIBUTE_UNUSED;
6448 allocate_reg_life_data ();
6449 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
6452 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6453 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6454 of the number of registers that died. */
6457 count_or_remove_death_notes (blocks, kill)
6463 for (i = n_basic_blocks - 1; i >= 0; --i)
6468 if (blocks && ! TEST_BIT (blocks, i))
6471 bb = BASIC_BLOCK (i);
6473 for (insn = bb->head;; insn = NEXT_INSN (insn))
6477 rtx *pprev = ®_NOTES (insn);
6482 switch (REG_NOTE_KIND (link))
6485 if (GET_CODE (XEXP (link, 0)) == REG)
6487 rtx reg = XEXP (link, 0);
6490 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
6493 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
6501 rtx next = XEXP (link, 1);
6502 free_EXPR_LIST_node (link);
6503 *pprev = link = next;
6509 pprev = &XEXP (link, 1);
6516 if (insn == bb->end)
6525 /* Update insns block within BB. */
6528 update_bb_for_insn (bb)
6533 if (! basic_block_for_insn)
6536 for (insn = bb->head; ; insn = NEXT_INSN (insn))
6538 set_block_for_insn (insn, bb);
6540 if (insn == bb->end)
6546 /* Record INSN's block as BB. */
6549 set_block_for_insn (insn, bb)
6553 size_t uid = INSN_UID (insn);
6554 if (uid >= basic_block_for_insn->num_elements)
6558 /* Add one-eighth the size so we don't keep calling xrealloc. */
6559 new_size = uid + (uid + 7) / 8;
6561 VARRAY_GROW (basic_block_for_insn, new_size);
6563 VARRAY_BB (basic_block_for_insn, uid) = bb;
6566 /* Record INSN's block number as BB. */
6567 /* ??? This has got to go. */
6570 set_block_num (insn, bb)
6574 set_block_for_insn (insn, BASIC_BLOCK (bb));
6577 /* Verify the CFG consistency. This function check some CFG invariants and
6578 aborts when something is wrong. Hope that this function will help to
6579 convert many optimization passes to preserve CFG consistent.
6581 Currently it does following checks:
6583 - test head/end pointers
6584 - overlapping of basic blocks
6585 - edge list corectness
6586 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6587 - tails of basic blocks (ensure that boundary is necesary)
6588 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6589 and NOTE_INSN_BASIC_BLOCK
6590 - check that all insns are in the basic blocks
6591 (except the switch handling code, barriers and notes)
6592 - check that all returns are followed by barriers
6594 In future it can be extended check a lot of other stuff as well
6595 (reachability of basic blocks, life information, etc. etc.). */
6600 const int max_uid = get_max_uid ();
6601 const rtx rtx_first = get_insns ();
6602 rtx last_head = get_last_insn ();
6603 basic_block *bb_info;
6605 int i, last_bb_num_seen, num_bb_notes, err = 0;
6607 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
6609 for (i = n_basic_blocks - 1; i >= 0; i--)
6611 basic_block bb = BASIC_BLOCK (i);
6612 rtx head = bb->head;
6615 /* Verify the end of the basic block is in the INSN chain. */
6616 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
6621 error ("End insn %d for block %d not found in the insn stream.",
6622 INSN_UID (end), bb->index);
6626 /* Work backwards from the end to the head of the basic block
6627 to verify the head is in the RTL chain. */
6628 for (; x != NULL_RTX; x = PREV_INSN (x))
6630 /* While walking over the insn chain, verify insns appear
6631 in only one basic block and initialize the BB_INFO array
6632 used by other passes. */
6633 if (bb_info[INSN_UID (x)] != NULL)
6635 error ("Insn %d is in multiple basic blocks (%d and %d)",
6636 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
6639 bb_info[INSN_UID (x)] = bb;
6646 error ("Head insn %d for block %d not found in the insn stream.",
6647 INSN_UID (head), bb->index);
6654 /* Now check the basic blocks (boundaries etc.) */
6655 for (i = n_basic_blocks - 1; i >= 0; i--)
6657 basic_block bb = BASIC_BLOCK (i);
6658 /* Check corectness of edge lists */
6667 "verify_flow_info: Basic block %d succ edge is corrupted\n",
6669 fprintf (stderr, "Predecessor: ");
6670 dump_edge_info (stderr, e, 0);
6671 fprintf (stderr, "\nSuccessor: ");
6672 dump_edge_info (stderr, e, 1);
6676 if (e->dest != EXIT_BLOCK_PTR)
6678 edge e2 = e->dest->pred;
6679 while (e2 && e2 != e)
6683 error ("Basic block %i edge lists are corrupted", bb->index);
6695 error ("Basic block %d pred edge is corrupted", bb->index);
6696 fputs ("Predecessor: ", stderr);
6697 dump_edge_info (stderr, e, 0);
6698 fputs ("\nSuccessor: ", stderr);
6699 dump_edge_info (stderr, e, 1);
6700 fputc ('\n', stderr);
6703 if (e->src != ENTRY_BLOCK_PTR)
6705 edge e2 = e->src->succ;
6706 while (e2 && e2 != e)
6710 error ("Basic block %i edge lists are corrupted", bb->index);
6717 /* OK pointers are correct. Now check the header of basic
6718 block. It ought to contain optional CODE_LABEL followed
6719 by NOTE_BASIC_BLOCK. */
6721 if (GET_CODE (x) == CODE_LABEL)
6725 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6731 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
6733 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6740 /* Do checks for empty blocks here */
6747 if (NOTE_INSN_BASIC_BLOCK_P (x))
6749 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6750 INSN_UID (x), bb->index);
6757 if (GET_CODE (x) == JUMP_INSN
6758 || GET_CODE (x) == CODE_LABEL
6759 || GET_CODE (x) == BARRIER)
6761 error ("In basic block %d:", bb->index);
6762 fatal_insn ("Flow control insn inside a basic block", x);
6770 last_bb_num_seen = -1;
6775 if (NOTE_INSN_BASIC_BLOCK_P (x))
6777 basic_block bb = NOTE_BASIC_BLOCK (x);
6779 if (bb->index != last_bb_num_seen + 1)
6780 fatal ("Basic blocks not numbered consecutively");
6781 last_bb_num_seen = bb->index;
6784 if (!bb_info[INSN_UID (x)])
6786 switch (GET_CODE (x))
6793 /* An addr_vec is placed outside any block block. */
6795 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
6796 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
6797 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
6802 /* But in any case, non-deletable labels can appear anywhere. */
6806 fatal_insn ("Insn outside basic block", x);
6811 && GET_CODE (x) == JUMP_INSN
6812 && returnjump_p (x) && ! condjump_p (x)
6813 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
6814 fatal_insn ("Return not followed by barrier", x);
6819 if (num_bb_notes != n_basic_blocks)
6820 fatal ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
6821 num_bb_notes, n_basic_blocks);
6830 /* Functions to access an edge list with a vector representation.
6831 Enough data is kept such that given an index number, the
6832 pred and succ that edge represents can be determined, or
6833 given a pred and a succ, its index number can be returned.
6834 This allows algorithms which consume a lot of memory to
6835 represent the normally full matrix of edge (pred,succ) with a
6836 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
6837 wasted space in the client code due to sparse flow graphs. */
6839 /* This functions initializes the edge list. Basically the entire
6840 flowgraph is processed, and all edges are assigned a number,
6841 and the data structure is filled in. */
6846 struct edge_list *elist;
6852 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
6856 /* Determine the number of edges in the flow graph by counting successor
6857 edges on each basic block. */
6858 for (x = 0; x < n_basic_blocks; x++)
6860 basic_block bb = BASIC_BLOCK (x);
6862 for (e = bb->succ; e; e = e->succ_next)
6865 /* Don't forget successors of the entry block. */
6866 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6869 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
6870 elist->num_blocks = block_count;
6871 elist->num_edges = num_edges;
6872 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
6876 /* Follow successors of the entry block, and register these edges. */
6877 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6879 elist->index_to_edge[num_edges] = e;
6883 for (x = 0; x < n_basic_blocks; x++)
6885 basic_block bb = BASIC_BLOCK (x);
6887 /* Follow all successors of blocks, and register these edges. */
6888 for (e = bb->succ; e; e = e->succ_next)
6890 elist->index_to_edge[num_edges] = e;
6897 /* This function free's memory associated with an edge list. */
6900 free_edge_list (elist)
6901 struct edge_list *elist;
6905 free (elist->index_to_edge);
6910 /* This function provides debug output showing an edge list. */
6913 print_edge_list (f, elist)
6915 struct edge_list *elist;
6918 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
6919 elist->num_blocks - 2, elist->num_edges);
6921 for (x = 0; x < elist->num_edges; x++)
6923 fprintf (f, " %-4d - edge(", x);
6924 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
6925 fprintf (f, "entry,");
6927 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
6929 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
6930 fprintf (f, "exit)\n");
6932 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
6936 /* This function provides an internal consistency check of an edge list,
6937 verifying that all edges are present, and that there are no
6941 verify_edge_list (f, elist)
6943 struct edge_list *elist;
6945 int x, pred, succ, index;
6948 for (x = 0; x < n_basic_blocks; x++)
6950 basic_block bb = BASIC_BLOCK (x);
6952 for (e = bb->succ; e; e = e->succ_next)
6954 pred = e->src->index;
6955 succ = e->dest->index;
6956 index = EDGE_INDEX (elist, e->src, e->dest);
6957 if (index == EDGE_INDEX_NO_EDGE)
6959 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
6962 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
6963 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
6964 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
6965 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
6966 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
6967 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
6970 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
6972 pred = e->src->index;
6973 succ = e->dest->index;
6974 index = EDGE_INDEX (elist, e->src, e->dest);
6975 if (index == EDGE_INDEX_NO_EDGE)
6977 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
6980 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
6981 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
6982 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
6983 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
6984 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
6985 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
6987 /* We've verified that all the edges are in the list, no lets make sure
6988 there are no spurious edges in the list. */
6990 for (pred = 0; pred < n_basic_blocks; pred++)
6991 for (succ = 0; succ < n_basic_blocks; succ++)
6993 basic_block p = BASIC_BLOCK (pred);
6994 basic_block s = BASIC_BLOCK (succ);
6998 for (e = p->succ; e; e = e->succ_next)
7004 for (e = s->pred; e; e = e->pred_next)
7010 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7011 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7012 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
7014 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7015 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7016 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
7017 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7018 BASIC_BLOCK (succ)));
7020 for (succ = 0; succ < n_basic_blocks; succ++)
7022 basic_block p = ENTRY_BLOCK_PTR;
7023 basic_block s = BASIC_BLOCK (succ);
7027 for (e = p->succ; e; e = e->succ_next)
7033 for (e = s->pred; e; e = e->pred_next)
7039 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7040 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7041 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
7043 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7044 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7045 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
7046 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
7047 BASIC_BLOCK (succ)));
7049 for (pred = 0; pred < n_basic_blocks; pred++)
7051 basic_block p = BASIC_BLOCK (pred);
7052 basic_block s = EXIT_BLOCK_PTR;
7056 for (e = p->succ; e; e = e->succ_next)
7062 for (e = s->pred; e; e = e->pred_next)
7068 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7069 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7070 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
7072 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7073 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7074 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7075 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7080 /* This routine will determine what, if any, edge there is between
7081 a specified predecessor and successor. */
7084 find_edge_index (edge_list, pred, succ)
7085 struct edge_list *edge_list;
7086 basic_block pred, succ;
7089 for (x = 0; x < NUM_EDGES (edge_list); x++)
7091 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7092 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7095 return (EDGE_INDEX_NO_EDGE);
7098 /* This function will remove an edge from the flow graph. */
7104 edge last_pred = NULL;
7105 edge last_succ = NULL;
7107 basic_block src, dest;
7110 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7116 last_succ->succ_next = e->succ_next;
7118 src->succ = e->succ_next;
7120 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7126 last_pred->pred_next = e->pred_next;
7128 dest->pred = e->pred_next;
7134 /* This routine will remove any fake successor edges for a basic block.
7135 When the edge is removed, it is also removed from whatever predecessor
7139 remove_fake_successors (bb)
7143 for (e = bb->succ; e;)
7147 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7152 /* This routine will remove all fake edges from the flow graph. If
7153 we remove all fake successors, it will automatically remove all
7154 fake predecessors. */
7157 remove_fake_edges ()
7161 for (x = 0; x < n_basic_blocks; x++)
7162 remove_fake_successors (BASIC_BLOCK (x));
7164 /* We've handled all successors except the entry block's. */
7165 remove_fake_successors (ENTRY_BLOCK_PTR);
7168 /* This function will add a fake edge between any block which has no
7169 successors, and the exit block. Some data flow equations require these
7173 add_noreturn_fake_exit_edges ()
7177 for (x = 0; x < n_basic_blocks; x++)
7178 if (BASIC_BLOCK (x)->succ == NULL)
7179 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7182 /* This function adds a fake edge between any infinite loops to the
7183 exit block. Some optimizations require a path from each node to
7186 See also Morgan, Figure 3.10, pp. 82-83.
7188 The current implementation is ugly, not attempting to minimize the
7189 number of inserted fake edges. To reduce the number of fake edges
7190 to insert, add fake edges from _innermost_ loops containing only
7191 nodes not reachable from the exit block. */
7194 connect_infinite_loops_to_exit ()
7196 basic_block unvisited_block;
7198 /* Perform depth-first search in the reverse graph to find nodes
7199 reachable from the exit block. */
7200 struct depth_first_search_dsS dfs_ds;
7202 flow_dfs_compute_reverse_init (&dfs_ds);
7203 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7205 /* Repeatedly add fake edges, updating the unreachable nodes. */
7208 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7209 if (!unvisited_block)
7211 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7212 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7215 flow_dfs_compute_reverse_finish (&dfs_ds);
7220 /* Redirect an edge's successor from one block to another. */
7223 redirect_edge_succ (e, new_succ)
7225 basic_block new_succ;
7229 /* Disconnect the edge from the old successor block. */
7230 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7232 *pe = (*pe)->pred_next;
7234 /* Reconnect the edge to the new successor block. */
7235 e->pred_next = new_succ->pred;
7240 /* Redirect an edge's predecessor from one block to another. */
7243 redirect_edge_pred (e, new_pred)
7245 basic_block new_pred;
7249 /* Disconnect the edge from the old predecessor block. */
7250 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7252 *pe = (*pe)->succ_next;
7254 /* Reconnect the edge to the new predecessor block. */
7255 e->succ_next = new_pred->succ;
7260 /* Dump the list of basic blocks in the bitmap NODES. */
7263 flow_nodes_print (str, nodes, file)
7265 const sbitmap nodes;
7273 fprintf (file, "%s { ", str);
7274 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
7275 fputs ("}\n", file);
7279 /* Dump the list of edges in the array EDGE_LIST. */
7282 flow_edge_list_print (str, edge_list, num_edges, file)
7284 const edge *edge_list;
7293 fprintf (file, "%s { ", str);
7294 for (i = 0; i < num_edges; i++)
7295 fprintf (file, "%d->%d ", edge_list[i]->src->index,
7296 edge_list[i]->dest->index);
7297 fputs ("}\n", file);
7301 /* Dump loop related CFG information. */
7304 flow_loops_cfg_dump (loops, file)
7305 const struct loops *loops;
7310 if (! loops->num || ! file || ! loops->cfg.dom)
7313 for (i = 0; i < n_basic_blocks; i++)
7317 fprintf (file, ";; %d succs { ", i);
7318 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
7319 fprintf (file, "%d ", succ->dest->index);
7320 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
7323 /* Dump the DFS node order. */
7324 if (loops->cfg.dfs_order)
7326 fputs (";; DFS order: ", file);
7327 for (i = 0; i < n_basic_blocks; i++)
7328 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
7331 /* Dump the reverse completion node order. */
7332 if (loops->cfg.rc_order)
7334 fputs (";; RC order: ", file);
7335 for (i = 0; i < n_basic_blocks; i++)
7336 fprintf (file, "%d ", loops->cfg.rc_order[i]);
7341 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7344 flow_loop_nested_p (outer, loop)
7348 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
7352 /* Dump the loop information specified by LOOP to the stream FILE
7353 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7355 flow_loop_dump (loop, file, loop_dump_aux, verbose)
7356 const struct loop *loop;
7358 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7361 if (! loop || ! loop->header)
7364 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
7365 loop->num, INSN_UID (loop->first->head),
7366 INSN_UID (loop->last->end),
7367 loop->shared ? " shared" : "",
7368 loop->invalid ? " invalid" : "");
7369 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
7370 loop->header->index, loop->latch->index,
7371 loop->pre_header ? loop->pre_header->index : -1,
7372 loop->first->index, loop->last->index);
7373 fprintf (file, ";; depth %d, level %d, outer %ld\n",
7374 loop->depth, loop->level,
7375 (long) (loop->outer ? loop->outer->num : -1));
7377 if (loop->pre_header_root)
7378 fprintf (file, ";; pre-header root %d\n",
7379 loop->pre_header_root->index);
7380 if (loop->pre_header_trace)
7381 flow_nodes_print (";; pre-header trace", loop->pre_header_trace,
7383 flow_edge_list_print (";; entry edges", loop->entry_edges,
7384 loop->num_entries, file);
7385 fprintf (file, ";; %d", loop->num_nodes);
7386 flow_nodes_print (" nodes", loop->nodes, file);
7387 flow_edge_list_print (";; exit edges", loop->exit_edges,
7388 loop->num_exits, file);
7389 if (loop->exits_doms)
7390 flow_nodes_print (";; exit doms", loop->exits_doms, file);
7392 loop_dump_aux (loop, file, verbose);
7396 /* Dump the loop information specified by LOOPS to the stream FILE,
7397 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7399 flow_loops_dump (loops, file, loop_dump_aux, verbose)
7400 const struct loops *loops;
7402 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7408 num_loops = loops->num;
7409 if (! num_loops || ! file)
7412 fprintf (file, ";; %d loops found, %d levels\n",
7413 num_loops, loops->levels);
7415 for (i = 0; i < num_loops; i++)
7417 struct loop *loop = &loops->array[i];
7419 flow_loop_dump (loop, file, loop_dump_aux, verbose);
7425 for (j = 0; j < i; j++)
7427 struct loop *oloop = &loops->array[j];
7429 if (loop->header == oloop->header)
7434 smaller = loop->num_nodes < oloop->num_nodes;
7436 /* If the union of LOOP and OLOOP is different than
7437 the larger of LOOP and OLOOP then LOOP and OLOOP
7438 must be disjoint. */
7439 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
7440 smaller ? oloop : loop);
7442 ";; loop header %d shared by loops %d, %d %s\n",
7443 loop->header->index, i, j,
7444 disjoint ? "disjoint" : "nested");
7451 flow_loops_cfg_dump (loops, file);
7455 /* Free all the memory allocated for LOOPS. */
7458 flow_loops_free (loops)
7459 struct loops *loops;
7468 /* Free the loop descriptors. */
7469 for (i = 0; i < loops->num; i++)
7471 struct loop *loop = &loops->array[i];
7473 if (loop->pre_header_trace)
7474 sbitmap_free (loop->pre_header_trace);
7476 sbitmap_free (loop->nodes);
7477 if (loop->entry_edges)
7478 free (loop->entry_edges);
7479 if (loop->exit_edges)
7480 free (loop->exit_edges);
7481 if (loop->exits_doms)
7482 sbitmap_free (loop->exits_doms);
7484 free (loops->array);
7485 loops->array = NULL;
7488 sbitmap_vector_free (loops->cfg.dom);
7489 if (loops->cfg.dfs_order)
7490 free (loops->cfg.dfs_order);
7492 if (loops->shared_headers)
7493 sbitmap_free (loops->shared_headers);
7498 /* Find the entry edges into the loop with header HEADER and nodes
7499 NODES and store in ENTRY_EDGES array. Return the number of entry
7500 edges from the loop. */
7503 flow_loop_entry_edges_find (header, nodes, entry_edges)
7505 const sbitmap nodes;
7511 *entry_edges = NULL;
7514 for (e = header->pred; e; e = e->pred_next)
7516 basic_block src = e->src;
7518 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7525 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
7528 for (e = header->pred; e; e = e->pred_next)
7530 basic_block src = e->src;
7532 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7533 (*entry_edges)[num_entries++] = e;
7540 /* Find the exit edges from the loop using the bitmap of loop nodes
7541 NODES and store in EXIT_EDGES array. Return the number of
7542 exit edges from the loop. */
7545 flow_loop_exit_edges_find (nodes, exit_edges)
7546 const sbitmap nodes;
7555 /* Check all nodes within the loop to see if there are any
7556 successors not in the loop. Note that a node may have multiple
7557 exiting edges ????? A node can have one jumping edge and one fallthru
7558 edge so only one of these can exit the loop. */
7560 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7561 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7563 basic_block dest = e->dest;
7565 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7573 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
7575 /* Store all exiting edges into an array. */
7577 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7578 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7580 basic_block dest = e->dest;
7582 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7583 (*exit_edges)[num_exits++] = e;
7591 /* Find the nodes contained within the loop with header HEADER and
7592 latch LATCH and store in NODES. Return the number of nodes within
7596 flow_loop_nodes_find (header, latch, nodes)
7605 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
7608 /* Start with only the loop header in the set of loop nodes. */
7609 sbitmap_zero (nodes);
7610 SET_BIT (nodes, header->index);
7612 header->loop_depth++;
7614 /* Push the loop latch on to the stack. */
7615 if (! TEST_BIT (nodes, latch->index))
7617 SET_BIT (nodes, latch->index);
7618 latch->loop_depth++;
7620 stack[sp++] = latch;
7629 for (e = node->pred; e; e = e->pred_next)
7631 basic_block ancestor = e->src;
7633 /* If each ancestor not marked as part of loop, add to set of
7634 loop nodes and push on to stack. */
7635 if (ancestor != ENTRY_BLOCK_PTR
7636 && ! TEST_BIT (nodes, ancestor->index))
7638 SET_BIT (nodes, ancestor->index);
7639 ancestor->loop_depth++;
7641 stack[sp++] = ancestor;
7649 /* Compute the depth first search order and store in the array
7650 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7651 RC_ORDER is non-zero, return the reverse completion number for each
7652 node. Returns the number of nodes visited. A depth first search
7653 tries to get as far away from the starting point as quickly as
7657 flow_depth_first_order_compute (dfs_order, rc_order)
7664 int rcnum = n_basic_blocks - 1;
7667 /* Allocate stack for back-tracking up CFG. */
7668 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
7671 /* Allocate bitmap to track nodes that have been visited. */
7672 visited = sbitmap_alloc (n_basic_blocks);
7674 /* None of the nodes in the CFG have been visited yet. */
7675 sbitmap_zero (visited);
7677 /* Push the first edge on to the stack. */
7678 stack[sp++] = ENTRY_BLOCK_PTR->succ;
7686 /* Look at the edge on the top of the stack. */
7691 /* Check if the edge destination has been visited yet. */
7692 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
7694 /* Mark that we have visited the destination. */
7695 SET_BIT (visited, dest->index);
7698 dfs_order[dfsnum++] = dest->index;
7702 /* Since the DEST node has been visited for the first
7703 time, check its successors. */
7704 stack[sp++] = dest->succ;
7708 /* There are no successors for the DEST node so assign
7709 its reverse completion number. */
7711 rc_order[rcnum--] = dest->index;
7716 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
7718 /* There are no more successors for the SRC node
7719 so assign its reverse completion number. */
7721 rc_order[rcnum--] = src->index;
7725 stack[sp - 1] = e->succ_next;
7732 sbitmap_free (visited);
7734 /* The number of nodes visited should not be greater than
7736 if (dfsnum > n_basic_blocks)
7739 /* There are some nodes left in the CFG that are unreachable. */
7740 if (dfsnum < n_basic_blocks)
7745 /* Compute the depth first search order on the _reverse_ graph and
7746 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7747 Returns the number of nodes visited.
7749 The computation is split into three pieces:
7751 flow_dfs_compute_reverse_init () creates the necessary data
7754 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7755 structures. The block will start the search.
7757 flow_dfs_compute_reverse_execute () continues (or starts) the
7758 search using the block on the top of the stack, stopping when the
7761 flow_dfs_compute_reverse_finish () destroys the necessary data
7764 Thus, the user will probably call ..._init(), call ..._add_bb() to
7765 add a beginning basic block to the stack, call ..._execute(),
7766 possibly add another bb to the stack and again call ..._execute(),
7767 ..., and finally call _finish(). */
7769 /* Initialize the data structures used for depth-first search on the
7770 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7771 added to the basic block stack. DATA is the current depth-first
7772 search context. If INITIALIZE_STACK is non-zero, there is an
7773 element on the stack. */
7776 flow_dfs_compute_reverse_init (data)
7777 depth_first_search_ds data;
7779 /* Allocate stack for back-tracking up CFG. */
7781 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
7782 * sizeof (basic_block));
7785 /* Allocate bitmap to track nodes that have been visited. */
7786 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
7788 /* None of the nodes in the CFG have been visited yet. */
7789 sbitmap_zero (data->visited_blocks);
7794 /* Add the specified basic block to the top of the dfs data
7795 structures. When the search continues, it will start at the
7799 flow_dfs_compute_reverse_add_bb (data, bb)
7800 depth_first_search_ds data;
7803 data->stack[data->sp++] = bb;
7807 /* Continue the depth-first search through the reverse graph starting
7808 with the block at the stack's top and ending when the stack is
7809 empty. Visited nodes are marked. Returns an unvisited basic
7810 block, or NULL if there is none available. */
7813 flow_dfs_compute_reverse_execute (data)
7814 depth_first_search_ds data;
7820 while (data->sp > 0)
7822 bb = data->stack[--data->sp];
7824 /* Mark that we have visited this node. */
7825 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
7827 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
7829 /* Perform depth-first search on adjacent vertices. */
7830 for (e = bb->pred; e; e = e->pred_next)
7831 flow_dfs_compute_reverse_add_bb (data, e->src);
7835 /* Determine if there are unvisited basic blocks. */
7836 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
7837 if (!TEST_BIT (data->visited_blocks, i))
7838 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
7842 /* Destroy the data structures needed for depth-first search on the
7846 flow_dfs_compute_reverse_finish (data)
7847 depth_first_search_ds data;
7850 sbitmap_free (data->visited_blocks);
7855 /* Find the root node of the loop pre-header extended basic block and
7856 the blocks along the trace from the root node to the loop header. */
7859 flow_loop_pre_header_scan (loop)
7864 if (loop->num_entries != 1)
7867 /* Find pre_header root note and trace from root node to pre_header. */
7868 loop->pre_header_trace = sbitmap_alloc (n_basic_blocks);
7869 sbitmap_zero (loop->pre_header_trace);
7871 ebb = loop->entry_edges[0]->src;
7872 SET_BIT (loop->pre_header_trace, ebb->index);
7873 while (ebb->pred->src != ENTRY_BLOCK_PTR
7874 && ! ebb->pred->pred_next)
7876 ebb = ebb->pred->src;
7877 SET_BIT (loop->pre_header_trace, ebb->index);
7880 loop->pre_header_root = ebb;
7884 /* Return the block for the pre-header of the loop with header
7885 HEADER where DOM specifies the dominator information. Return NULL if
7886 there is no pre-header. */
7889 flow_loop_pre_header_find (header, dom)
7893 basic_block pre_header;
7896 /* If block p is a predecessor of the header and is the only block
7897 that the header does not dominate, then it is the pre-header. */
7899 for (e = header->pred; e; e = e->pred_next)
7901 basic_block node = e->src;
7903 if (node != ENTRY_BLOCK_PTR
7904 && ! TEST_BIT (dom[node->index], header->index))
7906 if (pre_header == NULL)
7910 /* There are multiple edges into the header from outside
7911 the loop so there is no pre-header block. */
7920 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
7921 previously added. The insertion algorithm assumes that the loops
7922 are added in the order found by a depth first search of the CFG. */
7925 flow_loop_tree_node_add (prevloop, loop)
7926 struct loop *prevloop;
7930 if (flow_loop_nested_p (prevloop, loop))
7932 prevloop->inner = loop;
7933 loop->outer = prevloop;
7937 while (prevloop->outer)
7939 if (flow_loop_nested_p (prevloop->outer, loop))
7941 prevloop->next = loop;
7942 loop->outer = prevloop->outer;
7945 prevloop = prevloop->outer;
7948 prevloop->next = loop;
7952 /* Build the loop hierarchy tree for LOOPS. */
7955 flow_loops_tree_build (loops)
7956 struct loops *loops;
7961 num_loops = loops->num;
7965 /* Root the loop hierarchy tree with the first loop found.
7966 Since we used a depth first search this should be the
7968 loops->tree = &loops->array[0];
7969 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
7971 /* Add the remaining loops to the tree. */
7972 for (i = 1; i < num_loops; i++)
7973 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
7976 /* Helper function to compute loop nesting depth and enclosed loop level
7977 for the natural loop specified by LOOP at the loop depth DEPTH.
7978 Returns the loop level. */
7981 flow_loop_level_compute (loop, depth)
7991 /* Traverse loop tree assigning depth and computing level as the
7992 maximum level of all the inner loops of this loop. The loop
7993 level is equivalent to the height of the loop in the loop tree
7994 and corresponds to the number of enclosed loop levels (including
7996 for (inner = loop->inner; inner; inner = inner->next)
8000 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
8005 loop->level = level;
8006 loop->depth = depth;
8010 /* Compute the loop nesting depth and enclosed loop level for the loop
8011 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
8015 flow_loops_level_compute (loops)
8016 struct loops *loops;
8022 /* Traverse all the outer level loops. */
8023 for (loop = loops->tree; loop; loop = loop->next)
8025 level = flow_loop_level_compute (loop, 1);
8033 /* Find all the natural loops in the function and save in LOOPS structure
8034 and recalculate loop_depth information in basic block structures.
8035 FLAGS controls which loop information is collected.
8036 Return the number of natural loops found. */
8039 flow_loops_find (loops, flags)
8040 struct loops *loops;
8052 /* This function cannot be repeatedly called with different
8053 flags to build up the loop information. The loop tree
8054 must always be built if this function is called. */
8055 if (! (flags & LOOP_TREE))
8058 memset (loops, 0, sizeof (*loops));
8060 /* Taking care of this degenerate case makes the rest of
8061 this code simpler. */
8062 if (n_basic_blocks == 0)
8068 /* Compute the dominators. */
8069 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8070 compute_flow_dominators (dom, NULL);
8072 /* Count the number of loop edges (back edges). This should be the
8073 same as the number of natural loops. */
8076 for (b = 0; b < n_basic_blocks; b++)
8080 header = BASIC_BLOCK (b);
8081 header->loop_depth = 0;
8083 for (e = header->pred; e; e = e->pred_next)
8085 basic_block latch = e->src;
8087 /* Look for back edges where a predecessor is dominated
8088 by this block. A natural loop has a single entry
8089 node (header) that dominates all the nodes in the
8090 loop. It also has single back edge to the header
8091 from a latch node. Note that multiple natural loops
8092 may share the same header. */
8093 if (b != header->index)
8096 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8103 /* Compute depth first search order of the CFG so that outer
8104 natural loops will be found before inner natural loops. */
8105 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8106 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8107 flow_depth_first_order_compute (dfs_order, rc_order);
8109 /* Allocate loop structures. */
8111 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8113 headers = sbitmap_alloc (n_basic_blocks);
8114 sbitmap_zero (headers);
8116 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8117 sbitmap_zero (loops->shared_headers);
8119 /* Find and record information about all the natural loops
8122 for (b = 0; b < n_basic_blocks; b++)
8126 /* Search the nodes of the CFG in reverse completion order
8127 so that we can find outer loops first. */
8128 header = BASIC_BLOCK (rc_order[b]);
8130 /* Look for all the possible latch blocks for this header. */
8131 for (e = header->pred; e; e = e->pred_next)
8133 basic_block latch = e->src;
8135 /* Look for back edges where a predecessor is dominated
8136 by this block. A natural loop has a single entry
8137 node (header) that dominates all the nodes in the
8138 loop. It also has single back edge to the header
8139 from a latch node. Note that multiple natural loops
8140 may share the same header. */
8141 if (latch != ENTRY_BLOCK_PTR
8142 && TEST_BIT (dom[latch->index], header->index))
8146 loop = loops->array + num_loops;
8148 loop->header = header;
8149 loop->latch = latch;
8150 loop->num = num_loops;
8157 for (i = 0; i < num_loops; i++)
8159 struct loop *loop = &loops->array[i];
8162 /* Keep track of blocks that are loop headers so
8163 that we can tell which loops should be merged. */
8164 if (TEST_BIT (headers, loop->header->index))
8165 SET_BIT (loops->shared_headers, loop->header->index);
8166 SET_BIT (headers, loop->header->index);
8168 /* Find nodes contained within the loop. */
8169 loop->nodes = sbitmap_alloc (n_basic_blocks);
8171 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8173 /* Compute first and last blocks within the loop.
8174 These are often the same as the loop header and
8175 loop latch respectively, but this is not always
8178 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
8180 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
8182 if (flags & LOOP_EDGES)
8184 /* Find edges which enter the loop header.
8185 Note that the entry edges should only
8186 enter the header of a natural loop. */
8188 = flow_loop_entry_edges_find (loop->header,
8190 &loop->entry_edges);
8192 /* Find edges which exit the loop. */
8194 = flow_loop_exit_edges_find (loop->nodes,
8197 /* Determine which loop nodes dominate all the exits
8199 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8200 sbitmap_copy (loop->exits_doms, loop->nodes);
8201 for (j = 0; j < loop->num_exits; j++)
8202 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8203 dom[loop->exit_edges[j]->src->index]);
8205 /* The header of a natural loop must dominate
8207 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8211 if (flags & LOOP_PRE_HEADER)
8213 /* Look to see if the loop has a pre-header node. */
8215 = flow_loop_pre_header_find (loop->header, dom);
8217 flow_loop_pre_header_scan (loop);
8221 /* Natural loops with shared headers may either be disjoint or
8222 nested. Disjoint loops with shared headers cannot be inner
8223 loops and should be merged. For now just mark loops that share
8225 for (i = 0; i < num_loops; i++)
8226 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
8227 loops->array[i].shared = 1;
8229 sbitmap_free (headers);
8232 loops->num = num_loops;
8234 /* Save CFG derived information to avoid recomputing it. */
8235 loops->cfg.dom = dom;
8236 loops->cfg.dfs_order = dfs_order;
8237 loops->cfg.rc_order = rc_order;
8239 /* Build the loop hierarchy tree. */
8240 flow_loops_tree_build (loops);
8242 /* Assign the loop nesting depth and enclosed loop level for each
8244 loops->levels = flow_loops_level_compute (loops);
8250 /* Update the information regarding the loops in the CFG
8251 specified by LOOPS. */
8253 flow_loops_update (loops, flags)
8254 struct loops *loops;
8257 /* One day we may want to update the current loop data. For now
8258 throw away the old stuff and rebuild what we need. */
8260 flow_loops_free (loops);
8262 return flow_loops_find (loops, flags);
8266 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
8269 flow_loop_outside_edge_p (loop, e)
8270 const struct loop *loop;
8273 if (e->dest != loop->header)
8275 return (e->src == ENTRY_BLOCK_PTR)
8276 || ! TEST_BIT (loop->nodes, e->src->index);
8279 /* Clear LOG_LINKS fields of insns in a chain.
8280 Also clear the global_live_at_{start,end} fields of the basic block
8284 clear_log_links (insns)
8290 for (i = insns; i; i = NEXT_INSN (i))
8294 for (b = 0; b < n_basic_blocks; b++)
8296 basic_block bb = BASIC_BLOCK (b);
8298 bb->global_live_at_start = NULL;
8299 bb->global_live_at_end = NULL;
8302 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
8303 EXIT_BLOCK_PTR->global_live_at_start = NULL;
8306 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
8307 correspond to the hard registers, if any, set in that map. This
8308 could be done far more efficiently by having all sorts of special-cases
8309 with moving single words, but probably isn't worth the trouble. */
8312 reg_set_to_hard_reg_set (to, from)
8318 EXECUTE_IF_SET_IN_BITMAP
8321 if (i >= FIRST_PSEUDO_REGISTER)
8323 SET_HARD_REG_BIT (*to, i);