1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
136 #include "insn-flags.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 /* The obstack on which the flow graph components are allocated. */
173 struct obstack flow_obstack;
174 static char *flow_firstobj;
176 /* Number of basic blocks in the current function. */
180 /* Number of edges in the current function. */
184 /* The basic block array. */
186 varray_type basic_block_info;
188 /* The special entry and exit blocks. */
190 struct basic_block_def entry_exit_blocks[2]
195 NULL, /* local_set */
196 NULL, /* cond_local_set */
197 NULL, /* global_live_at_start */
198 NULL, /* global_live_at_end */
200 ENTRY_BLOCK, /* index */
202 -1, -1, /* eh_beg, eh_end */
210 NULL, /* local_set */
211 NULL, /* cond_local_set */
212 NULL, /* global_live_at_start */
213 NULL, /* global_live_at_end */
215 EXIT_BLOCK, /* index */
217 -1, -1, /* eh_beg, eh_end */
222 /* Nonzero if the second flow pass has completed. */
225 /* Maximum register number used in this function, plus one. */
229 /* Indexed by n, giving various register information */
231 varray_type reg_n_info;
233 /* Size of a regset for the current function,
234 in (1) bytes and (2) elements. */
239 /* Regset of regs live when calls to `setjmp'-like functions happen. */
240 /* ??? Does this exist only for the setjmp-clobbered warning message? */
242 regset regs_live_at_setjmp;
244 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
245 that have to go in the same hard reg.
246 The first two regs in the list are a pair, and the next two
247 are another pair, etc. */
250 /* Callback that determines if it's ok for a function to have no
251 noreturn attribute. */
252 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
254 /* Set of registers that may be eliminable. These are handled specially
255 in updating regs_ever_live. */
257 static HARD_REG_SET elim_reg_set;
259 /* The basic block structure for every insn, indexed by uid. */
261 varray_type basic_block_for_insn;
263 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
264 /* ??? Should probably be using LABEL_NUSES instead. It would take a
265 bit of surgery to be able to use or co-opt the routines in jump. */
267 static rtx label_value_list;
268 static rtx tail_recursion_label_list;
270 /* Holds information for tracking conditional register life information. */
271 struct reg_cond_life_info
273 /* An EXPR_LIST of conditions under which a register is dead. */
276 /* ??? Could store mask of bytes that are dead, so that we could finally
277 track lifetimes of multi-word registers accessed via subregs. */
280 /* For use in communicating between propagate_block and its subroutines.
281 Holds all information needed to compute life and def-use information. */
283 struct propagate_block_info
285 /* The basic block we're considering. */
288 /* Bit N is set if register N is conditionally or unconditionally live. */
291 /* Bit N is set if register N is set this insn. */
294 /* Element N is the next insn that uses (hard or pseudo) register N
295 within the current basic block; or zero, if there is no such insn. */
298 /* Contains a list of all the MEMs we are tracking for dead store
302 /* If non-null, record the set of registers set unconditionally in the
306 /* If non-null, record the set of registers set conditionally in the
308 regset cond_local_set;
310 #ifdef HAVE_conditional_execution
311 /* Indexed by register number, holds a reg_cond_life_info for each
312 register that is not unconditionally live or dead. */
313 splay_tree reg_cond_dead;
315 /* Bit N is set if register N is in an expression in reg_cond_dead. */
319 /* The length of mem_set_list. */
320 int mem_set_list_len;
322 /* Non-zero if the value of CC0 is live. */
325 /* Flags controling the set of information propagate_block collects. */
329 /* Maximum length of pbi->mem_set_list before we start dropping
330 new elements on the floor. */
331 #define MAX_MEM_SET_LIST_LEN 100
333 /* Store the data structures necessary for depth-first search. */
334 struct depth_first_search_dsS {
335 /* stack for backtracking during the algorithm */
338 /* number of edges in the stack. That is, positions 0, ..., sp-1
342 /* record of basic blocks already seen by depth-first search */
343 sbitmap visited_blocks;
345 typedef struct depth_first_search_dsS *depth_first_search_ds;
347 /* Forward declarations */
348 static int count_basic_blocks PARAMS ((rtx));
349 static void find_basic_blocks_1 PARAMS ((rtx));
350 static rtx find_label_refs PARAMS ((rtx, rtx));
351 static void clear_edges PARAMS ((void));
352 static void make_edges PARAMS ((rtx));
353 static void make_label_edge PARAMS ((sbitmap *, basic_block,
355 static void make_eh_edge PARAMS ((sbitmap *, eh_nesting_info *,
356 basic_block, rtx, int));
357 static void mark_critical_edges PARAMS ((void));
358 static void move_stray_eh_region_notes PARAMS ((void));
359 static void record_active_eh_regions PARAMS ((rtx));
361 static void commit_one_edge_insertion PARAMS ((edge));
363 static void delete_unreachable_blocks PARAMS ((void));
364 static void delete_eh_regions PARAMS ((void));
365 static int can_delete_note_p PARAMS ((rtx));
366 static void expunge_block PARAMS ((basic_block));
367 static int can_delete_label_p PARAMS ((rtx));
368 static int tail_recursion_label_p PARAMS ((rtx));
369 static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
371 static int merge_blocks_move_successor_nojumps PARAMS ((basic_block,
373 static int merge_blocks PARAMS ((edge,basic_block,basic_block));
374 static void try_merge_blocks PARAMS ((void));
375 static void tidy_fallthru_edges PARAMS ((void));
376 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
377 static void verify_wide_reg PARAMS ((int, rtx, rtx));
378 static void verify_local_live_at_start PARAMS ((regset, basic_block));
379 static int set_noop_p PARAMS ((rtx));
380 static int noop_move_p PARAMS ((rtx));
381 static void delete_noop_moves PARAMS ((rtx));
382 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
383 static void notice_stack_pointer_modification PARAMS ((rtx));
384 static void mark_reg PARAMS ((rtx, void *));
385 static void mark_regs_live_at_end PARAMS ((regset));
386 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
387 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
388 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
389 static rtx propagate_block_delete_libcall PARAMS ((basic_block, rtx, rtx));
390 static int insn_dead_p PARAMS ((struct propagate_block_info *,
392 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
394 static void mark_set_regs PARAMS ((struct propagate_block_info *,
396 static void mark_set_1 PARAMS ((struct propagate_block_info *,
397 enum rtx_code, rtx, rtx,
399 #ifdef HAVE_conditional_execution
400 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
402 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
403 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
404 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
406 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
407 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
408 static rtx not_reg_cond PARAMS ((rtx));
409 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
412 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
413 rtx, rtx, rtx, rtx, rtx));
414 static void find_auto_inc PARAMS ((struct propagate_block_info *,
416 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
418 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
420 static void mark_used_reg PARAMS ((struct propagate_block_info *,
422 static void mark_used_regs PARAMS ((struct propagate_block_info *,
424 void dump_flow_info PARAMS ((FILE *));
425 void debug_flow_info PARAMS ((void));
426 static void dump_edge_info PARAMS ((FILE *, edge, int));
427 static void print_rtl_and_abort PARAMS ((void));
429 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
431 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
433 static void remove_fake_successors PARAMS ((basic_block));
434 static void flow_nodes_print PARAMS ((const char *, const sbitmap,
436 static void flow_edge_list_print PARAMS ((const char *, const edge *,
438 static void flow_loops_cfg_dump PARAMS ((const struct loops *,
440 static int flow_loop_nested_p PARAMS ((struct loop *,
442 static int flow_loop_entry_edges_find PARAMS ((basic_block, const sbitmap,
444 static int flow_loop_exit_edges_find PARAMS ((const sbitmap, edge **));
445 static int flow_loop_nodes_find PARAMS ((basic_block, basic_block, sbitmap));
446 static int flow_depth_first_order_compute PARAMS ((int *, int *));
447 static void flow_dfs_compute_reverse_init
448 PARAMS ((depth_first_search_ds));
449 static void flow_dfs_compute_reverse_add_bb
450 PARAMS ((depth_first_search_ds, basic_block));
451 static basic_block flow_dfs_compute_reverse_execute
452 PARAMS ((depth_first_search_ds));
453 static void flow_dfs_compute_reverse_finish
454 PARAMS ((depth_first_search_ds));
455 static void flow_loop_pre_header_scan PARAMS ((struct loop *));
456 static basic_block flow_loop_pre_header_find PARAMS ((basic_block,
458 static void flow_loop_tree_node_add PARAMS ((struct loop *, struct loop *));
459 static void flow_loops_tree_build PARAMS ((struct loops *));
460 static int flow_loop_level_compute PARAMS ((struct loop *, int));
461 static int flow_loops_level_compute PARAMS ((struct loops *));
462 static void allocate_bb_life_data PARAMS ((void));
464 /* Find basic blocks of the current function.
465 F is the first insn of the function and NREGS the number of register
469 find_basic_blocks (f, nregs, file)
471 int nregs ATTRIBUTE_UNUSED;
472 FILE *file ATTRIBUTE_UNUSED;
476 /* Flush out existing data. */
477 if (basic_block_info != NULL)
483 /* Clear bb->aux on all extant basic blocks. We'll use this as a
484 tag for reuse during create_basic_block, just in case some pass
485 copies around basic block notes improperly. */
486 for (i = 0; i < n_basic_blocks; ++i)
487 BASIC_BLOCK (i)->aux = NULL;
489 VARRAY_FREE (basic_block_info);
492 n_basic_blocks = count_basic_blocks (f);
494 /* Size the basic block table. The actual structures will be allocated
495 by find_basic_blocks_1, since we want to keep the structure pointers
496 stable across calls to find_basic_blocks. */
497 /* ??? This whole issue would be much simpler if we called find_basic_blocks
498 exactly once, and thereafter we don't have a single long chain of
499 instructions at all until close to the end of compilation when we
500 actually lay them out. */
502 VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
504 find_basic_blocks_1 (f);
506 /* Record the block to which an insn belongs. */
507 /* ??? This should be done another way, by which (perhaps) a label is
508 tagged directly with the basic block that it starts. It is used for
509 more than that currently, but IMO that is the only valid use. */
511 max_uid = get_max_uid ();
513 /* Leave space for insns life_analysis makes in some cases for auto-inc.
514 These cases are rare, so we don't need too much space. */
515 max_uid += max_uid / 10;
518 compute_bb_for_insn (max_uid);
520 /* Discover the edges of our cfg. */
521 record_active_eh_regions (f);
522 make_edges (label_value_list);
524 /* Do very simple cleanup now, for the benefit of code that runs between
525 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
526 tidy_fallthru_edges ();
528 mark_critical_edges ();
530 #ifdef ENABLE_CHECKING
536 check_function_return_warnings ()
538 if (warn_missing_noreturn
539 && !TREE_THIS_VOLATILE (cfun->decl)
540 && EXIT_BLOCK_PTR->pred == NULL
541 && (lang_missing_noreturn_ok_p
542 && !lang_missing_noreturn_ok_p (cfun->decl)))
543 warning ("function might be possible candidate for attribute `noreturn'");
545 /* If we have a path to EXIT, then we do return. */
546 if (TREE_THIS_VOLATILE (cfun->decl)
547 && EXIT_BLOCK_PTR->pred != NULL)
548 warning ("`noreturn' function does return");
550 /* If the clobber_return_insn appears in some basic block, then we
551 do reach the end without returning a value. */
552 else if (warn_return_type
553 && cfun->x_clobber_return_insn != NULL
554 && EXIT_BLOCK_PTR->pred != NULL)
556 int max_uid = get_max_uid ();
558 /* If clobber_return_insn was excised by jump1, then renumber_insns
559 can make max_uid smaller than the number still recorded in our rtx.
560 That's fine, since this is a quick way of verifying that the insn
561 is no longer in the chain. */
562 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
564 /* Recompute insn->block mapping, since the initial mapping is
565 set before we delete unreachable blocks. */
566 compute_bb_for_insn (max_uid);
568 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
569 warning ("control reaches end of non-void function");
574 /* Count the basic blocks of the function. */
577 count_basic_blocks (f)
581 register RTX_CODE prev_code;
582 register int count = 0;
584 int call_had_abnormal_edge = 0;
586 prev_code = JUMP_INSN;
587 for (insn = f; insn; insn = NEXT_INSN (insn))
589 register RTX_CODE code = GET_CODE (insn);
591 if (code == CODE_LABEL
592 || (GET_RTX_CLASS (code) == 'i'
593 && (prev_code == JUMP_INSN
594 || prev_code == BARRIER
595 || (prev_code == CALL_INSN && call_had_abnormal_edge))))
598 /* Record whether this call created an edge. */
599 if (code == CALL_INSN)
601 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
602 int region = (note ? INTVAL (XEXP (note, 0)) : 1);
604 call_had_abnormal_edge = 0;
606 /* If there is an EH region or rethrow, we have an edge. */
607 if ((eh_region && region > 0)
608 || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
609 call_had_abnormal_edge = 1;
610 else if (nonlocal_goto_handler_labels && region >= 0)
611 /* If there is a nonlocal goto label and the specified
612 region number isn't -1, we have an edge. (0 means
613 no throw, but might have a nonlocal goto). */
614 call_had_abnormal_edge = 1;
619 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
621 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
625 /* The rest of the compiler works a bit smoother when we don't have to
626 check for the edge case of do-nothing functions with no basic blocks. */
629 emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
636 /* Scan a list of insns for labels referred to other than by jumps.
637 This is used to scan the alternatives of a call placeholder. */
639 find_label_refs (f, lvl)
645 for (insn = f; insn; insn = NEXT_INSN (insn))
646 if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
650 /* Make a list of all labels referred to other than by jumps
651 (which just don't have the REG_LABEL notes).
653 Make a special exception for labels followed by an ADDR*VEC,
654 as this would be a part of the tablejump setup code.
656 Make a special exception for the eh_return_stub_label, which
657 we know isn't part of any otherwise visible control flow.
659 Make a special exception to registers loaded with label
660 values just before jump insns that use them. */
662 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
663 if (REG_NOTE_KIND (note) == REG_LABEL)
665 rtx lab = XEXP (note, 0), next;
667 if (lab == eh_return_stub_label)
669 else if ((next = next_nonnote_insn (lab)) != NULL
670 && GET_CODE (next) == JUMP_INSN
671 && (GET_CODE (PATTERN (next)) == ADDR_VEC
672 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
674 else if (GET_CODE (lab) == NOTE)
676 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
677 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
680 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
687 /* Find all basic blocks of the function whose first insn is F.
689 Collect and return a list of labels whose addresses are taken. This
690 will be used in make_edges for use with computed gotos. */
693 find_basic_blocks_1 (f)
696 register rtx insn, next;
698 rtx bb_note = NULL_RTX;
699 rtx eh_list = NULL_RTX;
705 /* We process the instructions in a slightly different way than we did
706 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
707 closed out the previous block, so that it gets attached at the proper
708 place. Since this form should be equivalent to the previous,
709 count_basic_blocks continues to use the old form as a check. */
711 for (insn = f; insn; insn = next)
713 enum rtx_code code = GET_CODE (insn);
715 next = NEXT_INSN (insn);
721 int kind = NOTE_LINE_NUMBER (insn);
723 /* Keep a LIFO list of the currently active exception notes. */
724 if (kind == NOTE_INSN_EH_REGION_BEG)
725 eh_list = alloc_INSN_LIST (insn, eh_list);
726 else if (kind == NOTE_INSN_EH_REGION_END)
730 eh_list = XEXP (eh_list, 1);
731 free_INSN_LIST_node (t);
734 /* Look for basic block notes with which to keep the
735 basic_block_info pointers stable. Unthread the note now;
736 we'll put it back at the right place in create_basic_block.
737 Or not at all if we've already found a note in this block. */
738 else if (kind == NOTE_INSN_BASIC_BLOCK)
740 if (bb_note == NULL_RTX)
743 next = flow_delete_insn (insn);
749 /* A basic block starts at a label. If we've closed one off due
750 to a barrier or some such, no need to do it again. */
751 if (head != NULL_RTX)
753 /* While we now have edge lists with which other portions of
754 the compiler might determine a call ending a basic block
755 does not imply an abnormal edge, it will be a bit before
756 everything can be updated. So continue to emit a noop at
757 the end of such a block. */
758 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
760 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
761 end = emit_insn_after (nop, end);
764 create_basic_block (i++, head, end, bb_note);
772 /* A basic block ends at a jump. */
773 if (head == NULL_RTX)
777 /* ??? Make a special check for table jumps. The way this
778 happens is truly and amazingly gross. We are about to
779 create a basic block that contains just a code label and
780 an addr*vec jump insn. Worse, an addr_diff_vec creates
781 its own natural loop.
783 Prevent this bit of brain damage, pasting things together
784 correctly in make_edges.
786 The correct solution involves emitting the table directly
787 on the tablejump instruction as a note, or JUMP_LABEL. */
789 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
790 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
798 goto new_bb_inclusive;
801 /* A basic block ends at a barrier. It may be that an unconditional
802 jump already closed the basic block -- no need to do it again. */
803 if (head == NULL_RTX)
806 /* While we now have edge lists with which other portions of the
807 compiler might determine a call ending a basic block does not
808 imply an abnormal edge, it will be a bit before everything can
809 be updated. So continue to emit a noop at the end of such a
811 if (GET_CODE (end) == CALL_INSN && ! SIBLING_CALL_P (end))
813 rtx nop = gen_rtx_USE (VOIDmode, const0_rtx);
814 end = emit_insn_after (nop, end);
816 goto new_bb_exclusive;
820 /* Record whether this call created an edge. */
821 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
822 int region = (note ? INTVAL (XEXP (note, 0)) : 1);
823 int call_has_abnormal_edge = 0;
825 if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
827 /* Scan each of the alternatives for label refs. */
828 lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
829 lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
830 lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
831 /* Record its tail recursion label, if any. */
832 if (XEXP (PATTERN (insn), 3) != NULL_RTX)
833 trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
836 /* If there is an EH region or rethrow, we have an edge. */
837 if ((eh_list && region > 0)
838 || find_reg_note (insn, REG_EH_RETHROW, NULL_RTX))
839 call_has_abnormal_edge = 1;
840 else if (nonlocal_goto_handler_labels && region >= 0)
841 /* If there is a nonlocal goto label and the specified
842 region number isn't -1, we have an edge. (0 means
843 no throw, but might have a nonlocal goto). */
844 call_has_abnormal_edge = 1;
846 /* A basic block ends at a call that can either throw or
847 do a non-local goto. */
848 if (call_has_abnormal_edge)
851 if (head == NULL_RTX)
856 create_basic_block (i++, head, end, bb_note);
857 head = end = NULL_RTX;
865 if (GET_RTX_CLASS (code) == 'i')
867 if (head == NULL_RTX)
874 if (GET_RTX_CLASS (code) == 'i'
875 && GET_CODE (insn) != JUMP_INSN)
879 /* Make a list of all labels referred to other than by jumps.
881 Make a special exception for labels followed by an ADDR*VEC,
882 as this would be a part of the tablejump setup code.
884 Make a special exception for the eh_return_stub_label, which
885 we know isn't part of any otherwise visible control flow.
887 Make a special exception to registers loaded with label
888 values just before jump insns that use them. */
890 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
891 if (REG_NOTE_KIND (note) == REG_LABEL)
893 rtx lab = XEXP (note, 0), next;
895 if (lab == eh_return_stub_label)
897 else if ((next = next_nonnote_insn (lab)) != NULL
898 && GET_CODE (next) == JUMP_INSN
899 && (GET_CODE (PATTERN (next)) == ADDR_VEC
900 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
902 else if (GET_CODE (lab) == NOTE)
904 else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
905 && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
908 lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
913 if (head != NULL_RTX)
914 create_basic_block (i++, head, end, bb_note);
916 flow_delete_insn (bb_note);
918 if (i != n_basic_blocks)
921 label_value_list = lvl;
922 tail_recursion_label_list = trll;
925 /* Tidy the CFG by deleting unreachable code and whatnot. */
931 delete_unreachable_blocks ();
932 move_stray_eh_region_notes ();
933 record_active_eh_regions (f);
935 mark_critical_edges ();
937 /* Kill the data we won't maintain. */
938 free_EXPR_LIST_list (&label_value_list);
939 free_EXPR_LIST_list (&tail_recursion_label_list);
942 /* Create a new basic block consisting of the instructions between
943 HEAD and END inclusive. Reuses the note and basic block struct
944 in BB_NOTE, if any. */
947 create_basic_block (index, head, end, bb_note)
949 rtx head, end, bb_note;
954 && ! RTX_INTEGRATED_P (bb_note)
955 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
958 /* If we found an existing note, thread it back onto the chain. */
962 if (GET_CODE (head) == CODE_LABEL)
966 after = PREV_INSN (head);
970 if (after != bb_note && NEXT_INSN (after) != bb_note)
971 reorder_insns (bb_note, bb_note, after);
975 /* Otherwise we must create a note and a basic block structure.
976 Since we allow basic block structs in rtl, give the struct
977 the same lifetime by allocating it off the function obstack
978 rather than using malloc. */
980 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
981 memset (bb, 0, sizeof (*bb));
983 if (GET_CODE (head) == CODE_LABEL)
984 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
987 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
990 NOTE_BASIC_BLOCK (bb_note) = bb;
993 /* Always include the bb note in the block. */
994 if (NEXT_INSN (end) == bb_note)
1000 BASIC_BLOCK (index) = bb;
1002 /* Tag the block so that we know it has been used when considering
1003 other basic block notes. */
1007 /* Records the basic block struct in BB_FOR_INSN, for every instruction
1008 indexed by INSN_UID. MAX is the size of the array. */
1011 compute_bb_for_insn (max)
1016 if (basic_block_for_insn)
1017 VARRAY_FREE (basic_block_for_insn);
1018 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
1020 for (i = 0; i < n_basic_blocks; ++i)
1022 basic_block bb = BASIC_BLOCK (i);
1029 int uid = INSN_UID (insn);
1031 VARRAY_BB (basic_block_for_insn, uid) = bb;
1034 insn = NEXT_INSN (insn);
1039 /* Free the memory associated with the edge structures. */
1047 for (i = 0; i < n_basic_blocks; ++i)
1049 basic_block bb = BASIC_BLOCK (i);
1051 for (e = bb->succ; e; e = n)
1061 for (e = ENTRY_BLOCK_PTR->succ; e; e = n)
1067 ENTRY_BLOCK_PTR->succ = 0;
1068 EXIT_BLOCK_PTR->pred = 0;
1073 /* Identify the edges between basic blocks.
1075 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
1076 that are otherwise unreachable may be reachable with a non-local goto.
1078 BB_EH_END is an array indexed by basic block number in which we record
1079 the list of exception regions active at the end of the basic block. */
1082 make_edges (label_value_list)
1083 rtx label_value_list;
1086 eh_nesting_info *eh_nest_info = init_eh_nesting_info ();
1087 sbitmap *edge_cache = NULL;
1089 /* Assume no computed jump; revise as we create edges. */
1090 current_function_has_computed_jump = 0;
1092 /* Heavy use of computed goto in machine-generated code can lead to
1093 nearly fully-connected CFGs. In that case we spend a significant
1094 amount of time searching the edge lists for duplicates. */
1095 if (forced_labels || label_value_list)
1097 edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
1098 sbitmap_vector_zero (edge_cache, n_basic_blocks);
1101 /* By nature of the way these get numbered, block 0 is always the entry. */
1102 make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
1104 for (i = 0; i < n_basic_blocks; ++i)
1106 basic_block bb = BASIC_BLOCK (i);
1109 int force_fallthru = 0;
1111 /* Examine the last instruction of the block, and discover the
1112 ways we can leave the block. */
1115 code = GET_CODE (insn);
1118 if (code == JUMP_INSN)
1122 /* Recognize a non-local goto as a branch outside the
1123 current function. */
1124 if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
1127 /* ??? Recognize a tablejump and do the right thing. */
1128 else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1129 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1130 && GET_CODE (tmp) == JUMP_INSN
1131 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1132 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1137 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1138 vec = XVEC (PATTERN (tmp), 0);
1140 vec = XVEC (PATTERN (tmp), 1);
1142 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1143 make_label_edge (edge_cache, bb,
1144 XEXP (RTVEC_ELT (vec, j), 0), 0);
1146 /* Some targets (eg, ARM) emit a conditional jump that also
1147 contains the out-of-range target. Scan for these and
1148 add an edge if necessary. */
1149 if ((tmp = single_set (insn)) != NULL
1150 && SET_DEST (tmp) == pc_rtx
1151 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1152 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
1153 make_label_edge (edge_cache, bb,
1154 XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
1156 #ifdef CASE_DROPS_THROUGH
1157 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1158 us naturally detecting fallthru into the next block. */
1163 /* If this is a computed jump, then mark it as reaching
1164 everything on the label_value_list and forced_labels list. */
1165 else if (computed_jump_p (insn))
1167 current_function_has_computed_jump = 1;
1169 for (x = label_value_list; x; x = XEXP (x, 1))
1170 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1172 for (x = forced_labels; x; x = XEXP (x, 1))
1173 make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
1176 /* Returns create an exit out. */
1177 else if (returnjump_p (insn))
1178 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
1180 /* Otherwise, we have a plain conditional or unconditional jump. */
1183 if (! JUMP_LABEL (insn))
1185 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
1189 /* If this is a sibling call insn, then this is in effect a
1190 combined call and return, and so we need an edge to the
1191 exit block. No need to worry about EH edges, since we
1192 wouldn't have created the sibling call in the first place. */
1194 if (code == CALL_INSN && SIBLING_CALL_P (insn))
1195 make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
1196 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1198 /* If this is a CALL_INSN, then mark it as reaching the active EH
1199 handler for this CALL_INSN. If we're handling asynchronous
1200 exceptions then any insn can reach any of the active handlers.
1202 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1204 else if (code == CALL_INSN || asynchronous_exceptions)
1206 /* Add any appropriate EH edges. We do this unconditionally
1207 since there may be a REG_EH_REGION or REG_EH_RETHROW note
1208 on the call, and this needn't be within an EH region. */
1209 make_eh_edge (edge_cache, eh_nest_info, bb, insn, bb->eh_end);
1211 /* If we have asynchronous exceptions, do the same for *all*
1212 exception regions active in the block. */
1213 if (asynchronous_exceptions
1214 && bb->eh_beg != bb->eh_end)
1216 if (bb->eh_beg >= 0)
1217 make_eh_edge (edge_cache, eh_nest_info, bb,
1218 NULL_RTX, bb->eh_beg);
1220 for (x = bb->head; x != bb->end; x = NEXT_INSN (x))
1221 if (GET_CODE (x) == NOTE
1222 && (NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_BEG
1223 || NOTE_LINE_NUMBER (x) == NOTE_INSN_EH_REGION_END))
1225 int region = NOTE_EH_HANDLER (x);
1226 make_eh_edge (edge_cache, eh_nest_info, bb,
1231 if (code == CALL_INSN && nonlocal_goto_handler_labels)
1233 /* ??? This could be made smarter: in some cases it's possible
1234 to tell that certain calls will not do a nonlocal goto.
1236 For example, if the nested functions that do the nonlocal
1237 gotos do not have their addresses taken, then only calls to
1238 those functions or to other nested functions that use them
1239 could possibly do nonlocal gotos. */
1240 /* We do know that a REG_EH_REGION note with a value less
1241 than 0 is guaranteed not to perform a non-local goto. */
1242 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
1243 if (!note || INTVAL (XEXP (note, 0)) >= 0)
1244 for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
1245 make_label_edge (edge_cache, bb, XEXP (x, 0),
1246 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
1250 /* We know something about the structure of the function __throw in
1251 libgcc2.c. It is the only function that ever contains eh_stub
1252 labels. It modifies its return address so that the last block
1253 returns to one of the eh_stub labels within it. So we have to
1254 make additional edges in the flow graph. */
1255 if (i + 1 == n_basic_blocks && eh_return_stub_label != 0)
1256 make_label_edge (edge_cache, bb, eh_return_stub_label, EDGE_EH);
1258 /* Find out if we can drop through to the next block. */
1259 insn = next_nonnote_insn (insn);
1260 if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
1261 make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
1262 else if (i + 1 < n_basic_blocks)
1264 rtx tmp = BLOCK_HEAD (i + 1);
1265 if (GET_CODE (tmp) == NOTE)
1266 tmp = next_nonnote_insn (tmp);
1267 if (force_fallthru || insn == tmp)
1268 make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
1272 free_eh_nesting_info (eh_nest_info);
1274 sbitmap_vector_free (edge_cache);
1277 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1278 about the edge that is accumulated between calls. */
1281 make_edge (edge_cache, src, dst, flags)
1282 sbitmap *edge_cache;
1283 basic_block src, dst;
1289 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1290 many edges to them, and we didn't allocate memory for it. */
1291 use_edge_cache = (edge_cache
1292 && src != ENTRY_BLOCK_PTR
1293 && dst != EXIT_BLOCK_PTR);
1295 /* Make sure we don't add duplicate edges. */
1296 switch (use_edge_cache)
1299 /* Quick test for non-existance of the edge. */
1300 if (! TEST_BIT (edge_cache[src->index], dst->index))
1303 /* The edge exists; early exit if no work to do. */
1309 for (e = src->succ; e; e = e->succ_next)
1318 e = (edge) xcalloc (1, sizeof (*e));
1321 e->succ_next = src->succ;
1322 e->pred_next = dst->pred;
1331 SET_BIT (edge_cache[src->index], dst->index);
1334 /* Create an edge from a basic block to a label. */
1337 make_label_edge (edge_cache, src, label, flags)
1338 sbitmap *edge_cache;
1343 if (GET_CODE (label) != CODE_LABEL)
1346 /* If the label was never emitted, this insn is junk, but avoid a
1347 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1348 as a result of a syntax error and a diagnostic has already been
1351 if (INSN_UID (label) == 0)
1354 make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
1357 /* Create the edges generated by INSN in REGION. */
1360 make_eh_edge (edge_cache, eh_nest_info, src, insn, region)
1361 sbitmap *edge_cache;
1362 eh_nesting_info *eh_nest_info;
1367 handler_info **handler_list;
1370 is_call = (insn && GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
1371 num = reachable_handlers (region, eh_nest_info, insn, &handler_list);
1374 make_label_edge (edge_cache, src, handler_list[num]->handler_label,
1375 EDGE_ABNORMAL | EDGE_EH | is_call);
1379 /* EH_REGION notes appearing between basic blocks is ambiguous, and even
1380 dangerous if we intend to move basic blocks around. Move such notes
1381 into the following block. */
1384 move_stray_eh_region_notes ()
1389 if (n_basic_blocks < 2)
1392 b2 = BASIC_BLOCK (n_basic_blocks - 1);
1393 for (i = n_basic_blocks - 2; i >= 0; --i, b2 = b1)
1395 rtx insn, next, list = NULL_RTX;
1397 b1 = BASIC_BLOCK (i);
1398 for (insn = NEXT_INSN (b1->end); insn != b2->head; insn = next)
1400 next = NEXT_INSN (insn);
1401 if (GET_CODE (insn) == NOTE
1402 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
1403 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
1405 /* Unlink from the insn chain. */
1406 NEXT_INSN (PREV_INSN (insn)) = next;
1407 PREV_INSN (next) = PREV_INSN (insn);
1410 NEXT_INSN (insn) = list;
1415 if (list == NULL_RTX)
1418 /* Find where to insert these things. */
1420 if (GET_CODE (insn) == CODE_LABEL)
1421 insn = NEXT_INSN (insn);
1425 next = NEXT_INSN (list);
1426 add_insn_after (list, insn);
1432 /* Recompute eh_beg/eh_end for each basic block. */
1435 record_active_eh_regions (f)
1438 rtx insn, eh_list = NULL_RTX;
1440 basic_block bb = BASIC_BLOCK (0);
1442 for (insn = f; insn; insn = NEXT_INSN (insn))
1444 if (bb->head == insn)
1445 bb->eh_beg = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1447 if (GET_CODE (insn) == NOTE)
1449 int kind = NOTE_LINE_NUMBER (insn);
1450 if (kind == NOTE_INSN_EH_REGION_BEG)
1451 eh_list = alloc_INSN_LIST (insn, eh_list);
1452 else if (kind == NOTE_INSN_EH_REGION_END)
1454 rtx t = XEXP (eh_list, 1);
1455 free_INSN_LIST_node (eh_list);
1460 if (bb->end == insn)
1462 bb->eh_end = (eh_list ? NOTE_EH_HANDLER (XEXP (eh_list, 0)) : -1);
1464 if (i == n_basic_blocks)
1466 bb = BASIC_BLOCK (i);
1471 /* Identify critical edges and set the bits appropriately. */
1474 mark_critical_edges ()
1476 int i, n = n_basic_blocks;
1479 /* We begin with the entry block. This is not terribly important now,
1480 but could be if a front end (Fortran) implemented alternate entry
1482 bb = ENTRY_BLOCK_PTR;
1489 /* (1) Critical edges must have a source with multiple successors. */
1490 if (bb->succ && bb->succ->succ_next)
1492 for (e = bb->succ; e; e = e->succ_next)
1494 /* (2) Critical edges must have a destination with multiple
1495 predecessors. Note that we know there is at least one
1496 predecessor -- the edge we followed to get here. */
1497 if (e->dest->pred->pred_next)
1498 e->flags |= EDGE_CRITICAL;
1500 e->flags &= ~EDGE_CRITICAL;
1505 for (e = bb->succ; e; e = e->succ_next)
1506 e->flags &= ~EDGE_CRITICAL;
1511 bb = BASIC_BLOCK (i);
1515 /* Split a block BB after insn INSN creating a new fallthru edge.
1516 Return the new edge. Note that to keep other parts of the compiler happy,
1517 this function renumbers all the basic blocks so that the new
1518 one has a number one greater than the block split. */
1521 split_block (bb, insn)
1531 /* There is no point splitting the block after its end. */
1532 if (bb->end == insn)
1535 /* Create the new structures. */
1536 new_bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*new_bb));
1537 new_edge = (edge) xcalloc (1, sizeof (*new_edge));
1540 memset (new_bb, 0, sizeof (*new_bb));
1542 new_bb->head = NEXT_INSN (insn);
1543 new_bb->end = bb->end;
1546 new_bb->succ = bb->succ;
1547 bb->succ = new_edge;
1548 new_bb->pred = new_edge;
1549 new_bb->count = bb->count;
1550 new_bb->loop_depth = bb->loop_depth;
1553 new_edge->dest = new_bb;
1554 new_edge->flags = EDGE_FALLTHRU;
1555 new_edge->probability = REG_BR_PROB_BASE;
1556 new_edge->count = bb->count;
1558 /* Redirect the src of the successor edges of bb to point to new_bb. */
1559 for (e = new_bb->succ; e; e = e->succ_next)
1562 /* Place the new block just after the block being split. */
1563 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1565 /* Some parts of the compiler expect blocks to be number in
1566 sequential order so insert the new block immediately after the
1567 block being split.. */
1569 for (i = n_basic_blocks - 1; i > j + 1; --i)
1571 basic_block tmp = BASIC_BLOCK (i - 1);
1572 BASIC_BLOCK (i) = tmp;
1576 BASIC_BLOCK (i) = new_bb;
1579 /* Create the basic block note. */
1580 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1582 NOTE_BASIC_BLOCK (bb_note) = new_bb;
1583 new_bb->head = bb_note;
1585 update_bb_for_insn (new_bb);
1587 if (bb->global_live_at_start)
1589 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1590 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1591 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
1593 /* We now have to calculate which registers are live at the end
1594 of the split basic block and at the start of the new basic
1595 block. Start with those registers that are known to be live
1596 at the end of the original basic block and get
1597 propagate_block to determine which registers are live. */
1598 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
1599 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
1600 COPY_REG_SET (bb->global_live_at_end,
1601 new_bb->global_live_at_start);
1608 /* Split a (typically critical) edge. Return the new block.
1609 Abort on abnormal edges.
1611 ??? The code generally expects to be called on critical edges.
1612 The case of a block ending in an unconditional jump to a
1613 block with multiple predecessors is not handled optimally. */
1616 split_edge (edge_in)
1619 basic_block old_pred, bb, old_succ;
1624 /* Abnormal edges cannot be split. */
1625 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1628 old_pred = edge_in->src;
1629 old_succ = edge_in->dest;
1631 /* Remove the existing edge from the destination's pred list. */
1634 for (pp = &old_succ->pred; *pp != edge_in; pp = &(*pp)->pred_next)
1636 *pp = edge_in->pred_next;
1637 edge_in->pred_next = NULL;
1640 /* Create the new structures. */
1641 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof (*bb));
1642 edge_out = (edge) xcalloc (1, sizeof (*edge_out));
1645 memset (bb, 0, sizeof (*bb));
1647 /* ??? This info is likely going to be out of date very soon. */
1648 if (old_succ->global_live_at_start)
1650 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1651 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1652 COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
1653 COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
1658 bb->succ = edge_out;
1659 bb->count = edge_in->count;
1662 edge_in->flags &= ~EDGE_CRITICAL;
1664 edge_out->pred_next = old_succ->pred;
1665 edge_out->succ_next = NULL;
1667 edge_out->dest = old_succ;
1668 edge_out->flags = EDGE_FALLTHRU;
1669 edge_out->probability = REG_BR_PROB_BASE;
1670 edge_out->count = edge_in->count;
1672 old_succ->pred = edge_out;
1674 /* Tricky case -- if there existed a fallthru into the successor
1675 (and we're not it) we must add a new unconditional jump around
1676 the new block we're actually interested in.
1678 Further, if that edge is critical, this means a second new basic
1679 block must be created to hold it. In order to simplify correct
1680 insn placement, do this before we touch the existing basic block
1681 ordering for the block we were really wanting. */
1682 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1685 for (e = edge_out->pred_next; e; e = e->pred_next)
1686 if (e->flags & EDGE_FALLTHRU)
1691 basic_block jump_block;
1694 if ((e->flags & EDGE_CRITICAL) == 0
1695 && e->src != ENTRY_BLOCK_PTR)
1697 /* Non critical -- we can simply add a jump to the end
1698 of the existing predecessor. */
1699 jump_block = e->src;
1703 /* We need a new block to hold the jump. The simplest
1704 way to do the bulk of the work here is to recursively
1706 jump_block = split_edge (e);
1707 e = jump_block->succ;
1710 /* Now add the jump insn ... */
1711 pos = emit_jump_insn_after (gen_jump (old_succ->head),
1713 jump_block->end = pos;
1714 if (basic_block_for_insn)
1715 set_block_for_insn (pos, jump_block);
1716 emit_barrier_after (pos);
1718 /* ... let jump know that label is in use, ... */
1719 JUMP_LABEL (pos) = old_succ->head;
1720 ++LABEL_NUSES (old_succ->head);
1722 /* ... and clear fallthru on the outgoing edge. */
1723 e->flags &= ~EDGE_FALLTHRU;
1725 /* Continue splitting the interesting edge. */
1729 /* Place the new block just in front of the successor. */
1730 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
1731 if (old_succ == EXIT_BLOCK_PTR)
1732 j = n_basic_blocks - 1;
1734 j = old_succ->index;
1735 for (i = n_basic_blocks - 1; i > j; --i)
1737 basic_block tmp = BASIC_BLOCK (i - 1);
1738 BASIC_BLOCK (i) = tmp;
1741 BASIC_BLOCK (i) = bb;
1744 /* Create the basic block note.
1746 Where we place the note can have a noticable impact on the generated
1747 code. Consider this cfg:
1757 If we need to insert an insn on the edge from block 0 to block 1,
1758 we want to ensure the instructions we insert are outside of any
1759 loop notes that physically sit between block 0 and block 1. Otherwise
1760 we confuse the loop optimizer into thinking the loop is a phony. */
1761 if (old_succ != EXIT_BLOCK_PTR
1762 && PREV_INSN (old_succ->head)
1763 && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
1764 && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
1765 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
1766 PREV_INSN (old_succ->head));
1767 else if (old_succ != EXIT_BLOCK_PTR)
1768 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, old_succ->head);
1770 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
1771 NOTE_BASIC_BLOCK (bb_note) = bb;
1772 bb->head = bb->end = bb_note;
1774 /* Not quite simple -- for non-fallthru edges, we must adjust the
1775 predecessor's jump instruction to target our new block. */
1776 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1778 rtx tmp, insn = old_pred->end;
1779 rtx old_label = old_succ->head;
1780 rtx new_label = gen_label_rtx ();
1782 if (GET_CODE (insn) != JUMP_INSN)
1785 /* ??? Recognize a tablejump and adjust all matching cases. */
1786 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
1787 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
1788 && GET_CODE (tmp) == JUMP_INSN
1789 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
1790 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
1795 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
1796 vec = XVEC (PATTERN (tmp), 0);
1798 vec = XVEC (PATTERN (tmp), 1);
1800 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
1801 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
1803 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (VOIDmode, new_label);
1804 --LABEL_NUSES (old_label);
1805 ++LABEL_NUSES (new_label);
1808 /* Handle casesi dispatch insns */
1809 if ((tmp = single_set (insn)) != NULL
1810 && SET_DEST (tmp) == pc_rtx
1811 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
1812 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
1813 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
1815 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
1817 --LABEL_NUSES (old_label);
1818 ++LABEL_NUSES (new_label);
1823 /* This would have indicated an abnormal edge. */
1824 if (computed_jump_p (insn))
1827 /* A return instruction can't be redirected. */
1828 if (returnjump_p (insn))
1831 /* If the insn doesn't go where we think, we're confused. */
1832 if (JUMP_LABEL (insn) != old_label)
1835 redirect_jump (insn, new_label, 0);
1838 emit_label_before (new_label, bb_note);
1839 bb->head = new_label;
1845 /* Queue instructions for insertion on an edge between two basic blocks.
1846 The new instructions and basic blocks (if any) will not appear in the
1847 CFG until commit_edge_insertions is called. */
1850 insert_insn_on_edge (pattern, e)
1854 /* We cannot insert instructions on an abnormal critical edge.
1855 It will be easier to find the culprit if we die now. */
1856 if ((e->flags & (EDGE_ABNORMAL|EDGE_CRITICAL))
1857 == (EDGE_ABNORMAL|EDGE_CRITICAL))
1860 if (e->insns == NULL_RTX)
1863 push_to_sequence (e->insns);
1865 emit_insn (pattern);
1867 e->insns = get_insns ();
1871 /* Update the CFG for the instructions queued on edge E. */
1874 commit_one_edge_insertion (e)
1877 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1880 /* Pull the insns off the edge now since the edge might go away. */
1882 e->insns = NULL_RTX;
1884 /* Figure out where to put these things. If the destination has
1885 one predecessor, insert there. Except for the exit block. */
1886 if (e->dest->pred->pred_next == NULL
1887 && e->dest != EXIT_BLOCK_PTR)
1891 /* Get the location correct wrt a code label, and "nice" wrt
1892 a basic block note, and before everything else. */
1894 if (GET_CODE (tmp) == CODE_LABEL)
1895 tmp = NEXT_INSN (tmp);
1896 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1897 tmp = NEXT_INSN (tmp);
1898 if (tmp == bb->head)
1901 after = PREV_INSN (tmp);
1904 /* If the source has one successor and the edge is not abnormal,
1905 insert there. Except for the entry block. */
1906 else if ((e->flags & EDGE_ABNORMAL) == 0
1907 && e->src->succ->succ_next == NULL
1908 && e->src != ENTRY_BLOCK_PTR)
1911 /* It is possible to have a non-simple jump here. Consider a target
1912 where some forms of unconditional jumps clobber a register. This
1913 happens on the fr30 for example.
1915 We know this block has a single successor, so we can just emit
1916 the queued insns before the jump. */
1917 if (GET_CODE (bb->end) == JUMP_INSN)
1923 /* We'd better be fallthru, or we've lost track of what's what. */
1924 if ((e->flags & EDGE_FALLTHRU) == 0)
1931 /* Otherwise we must split the edge. */
1934 bb = split_edge (e);
1938 /* Now that we've found the spot, do the insertion. */
1940 /* Set the new block number for these insns, if structure is allocated. */
1941 if (basic_block_for_insn)
1944 for (i = insns; i != NULL_RTX; i = NEXT_INSN (i))
1945 set_block_for_insn (i, bb);
1950 emit_insns_before (insns, before);
1951 if (before == bb->head)
1954 last = prev_nonnote_insn (before);
1958 last = emit_insns_after (insns, after);
1959 if (after == bb->end)
1963 if (returnjump_p (last))
1965 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1966 This is not currently a problem because this only happens
1967 for the (single) epilogue, which already has a fallthru edge
1971 if (e->dest != EXIT_BLOCK_PTR
1972 || e->succ_next != NULL
1973 || (e->flags & EDGE_FALLTHRU) == 0)
1975 e->flags &= ~EDGE_FALLTHRU;
1977 emit_barrier_after (last);
1981 flow_delete_insn (before);
1983 else if (GET_CODE (last) == JUMP_INSN)
1987 /* Update the CFG for all queued instructions. */
1990 commit_edge_insertions ()
1995 #ifdef ENABLE_CHECKING
1996 verify_flow_info ();
2000 bb = ENTRY_BLOCK_PTR;
2005 for (e = bb->succ; e; e = next)
2007 next = e->succ_next;
2009 commit_one_edge_insertion (e);
2012 if (++i >= n_basic_blocks)
2014 bb = BASIC_BLOCK (i);
2018 /* Add fake edges to the function exit for any non constant calls in
2019 the bitmap of blocks specified by BLOCKS or to the whole CFG if
2020 BLOCKS is zero. Return the nuber of blocks that were split. */
2023 flow_call_edges_add (blocks)
2027 int blocks_split = 0;
2031 /* Map bb indicies into basic block pointers since split_block
2032 will renumber the basic blocks. */
2034 bbs = xmalloc (n_basic_blocks * sizeof (*bbs));
2038 for (i = 0; i < n_basic_blocks; i++)
2039 bbs[bb_num++] = BASIC_BLOCK (i);
2043 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
2045 bbs[bb_num++] = BASIC_BLOCK (i);
2050 /* Now add fake edges to the function exit for any non constant
2051 calls since there is no way that we can determine if they will
2054 for (i = 0; i < bb_num; i++)
2056 basic_block bb = bbs[i];
2060 for (insn = bb->end; ; insn = prev_insn)
2062 prev_insn = PREV_INSN (insn);
2063 if (GET_CODE (insn) == CALL_INSN && ! CONST_CALL_P (insn))
2067 /* Note that the following may create a new basic block
2068 and renumber the existing basic blocks. */
2069 e = split_block (bb, insn);
2073 make_edge (NULL, bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2075 if (insn == bb->head)
2081 verify_flow_info ();
2084 return blocks_split;
2087 /* Delete all unreachable basic blocks. */
2090 delete_unreachable_blocks ()
2092 basic_block *worklist, *tos;
2093 int deleted_handler;
2098 tos = worklist = (basic_block *) xmalloc (sizeof (basic_block) * n);
2100 /* Use basic_block->aux as a marker. Clear them all. */
2102 for (i = 0; i < n; ++i)
2103 BASIC_BLOCK (i)->aux = NULL;
2105 /* Add our starting points to the worklist. Almost always there will
2106 be only one. It isn't inconcievable that we might one day directly
2107 support Fortran alternate entry points. */
2109 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
2113 /* Mark the block with a handy non-null value. */
2117 /* Iterate: find everything reachable from what we've already seen. */
2119 while (tos != worklist)
2121 basic_block b = *--tos;
2123 for (e = b->succ; e; e = e->succ_next)
2131 /* Delete all unreachable basic blocks. Count down so that we don't
2132 interfere with the block renumbering that happens in flow_delete_block. */
2134 deleted_handler = 0;
2136 for (i = n - 1; i >= 0; --i)
2138 basic_block b = BASIC_BLOCK (i);
2141 /* This block was found. Tidy up the mark. */
2144 deleted_handler |= flow_delete_block (b);
2147 tidy_fallthru_edges ();
2149 /* If we deleted an exception handler, we may have EH region begin/end
2150 blocks to remove as well. */
2151 if (deleted_handler)
2152 delete_eh_regions ();
2157 /* Find EH regions for which there is no longer a handler, and delete them. */
2160 delete_eh_regions ()
2164 update_rethrow_references ();
2166 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2167 if (GET_CODE (insn) == NOTE)
2169 if ((NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2170 || (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2172 int num = NOTE_EH_HANDLER (insn);
2173 /* A NULL handler indicates a region is no longer needed,
2174 as long as its rethrow label isn't used. */
2175 if (get_first_handler (num) == NULL && ! rethrow_used (num))
2177 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2178 NOTE_SOURCE_FILE (insn) = 0;
2184 /* Return true if NOTE is not one of the ones that must be kept paired,
2185 so that we may simply delete them. */
2188 can_delete_note_p (note)
2191 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
2192 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
2195 /* Unlink a chain of insns between START and FINISH, leaving notes
2196 that must be paired. */
2199 flow_delete_insn_chain (start, finish)
2202 /* Unchain the insns one by one. It would be quicker to delete all
2203 of these with a single unchaining, rather than one at a time, but
2204 we need to keep the NOTE's. */
2210 next = NEXT_INSN (start);
2211 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
2213 else if (GET_CODE (start) == CODE_LABEL
2214 && ! can_delete_label_p (start))
2216 const char *name = LABEL_NAME (start);
2217 PUT_CODE (start, NOTE);
2218 NOTE_LINE_NUMBER (start) = NOTE_INSN_DELETED_LABEL;
2219 NOTE_SOURCE_FILE (start) = name;
2222 next = flow_delete_insn (start);
2224 if (start == finish)
2230 /* Delete the insns in a (non-live) block. We physically delete every
2231 non-deleted-note insn, and update the flow graph appropriately.
2233 Return nonzero if we deleted an exception handler. */
2235 /* ??? Preserving all such notes strikes me as wrong. It would be nice
2236 to post-process the stream to remove empty blocks, loops, ranges, etc. */
2239 flow_delete_block (b)
2242 int deleted_handler = 0;
2245 /* If the head of this block is a CODE_LABEL, then it might be the
2246 label for an exception handler which can't be reached.
2248 We need to remove the label from the exception_handler_label list
2249 and remove the associated NOTE_INSN_EH_REGION_BEG and
2250 NOTE_INSN_EH_REGION_END notes. */
2254 never_reached_warning (insn);
2256 if (GET_CODE (insn) == CODE_LABEL)
2258 rtx x, *prev = &exception_handler_labels;
2260 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2262 if (XEXP (x, 0) == insn)
2264 /* Found a match, splice this label out of the EH label list. */
2265 *prev = XEXP (x, 1);
2266 XEXP (x, 1) = NULL_RTX;
2267 XEXP (x, 0) = NULL_RTX;
2269 /* Remove the handler from all regions */
2270 remove_handler (insn);
2271 deleted_handler = 1;
2274 prev = &XEXP (x, 1);
2278 /* Include any jump table following the basic block. */
2280 if (GET_CODE (end) == JUMP_INSN
2281 && (tmp = JUMP_LABEL (end)) != NULL_RTX
2282 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
2283 && GET_CODE (tmp) == JUMP_INSN
2284 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
2285 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
2288 /* Include any barrier that may follow the basic block. */
2289 tmp = next_nonnote_insn (end);
2290 if (tmp && GET_CODE (tmp) == BARRIER)
2293 /* Selectively delete the entire chain. */
2294 flow_delete_insn_chain (insn, end);
2296 /* Remove the edges into and out of this block. Note that there may
2297 indeed be edges in, if we are removing an unreachable loop. */
2301 for (e = b->pred; e; e = next)
2303 for (q = &e->src->succ; *q != e; q = &(*q)->succ_next)
2306 next = e->pred_next;
2310 for (e = b->succ; e; e = next)
2312 for (q = &e->dest->pred; *q != e; q = &(*q)->pred_next)
2315 next = e->succ_next;
2324 /* Remove the basic block from the array, and compact behind it. */
2327 return deleted_handler;
2330 /* Remove block B from the basic block array and compact behind it. */
2336 int i, n = n_basic_blocks;
2338 for (i = b->index; i + 1 < n; ++i)
2340 basic_block x = BASIC_BLOCK (i + 1);
2341 BASIC_BLOCK (i) = x;
2345 basic_block_info->num_elements--;
2349 /* Delete INSN by patching it out. Return the next insn. */
2352 flow_delete_insn (insn)
2355 rtx prev = PREV_INSN (insn);
2356 rtx next = NEXT_INSN (insn);
2359 PREV_INSN (insn) = NULL_RTX;
2360 NEXT_INSN (insn) = NULL_RTX;
2361 INSN_DELETED_P (insn) = 1;
2364 NEXT_INSN (prev) = next;
2366 PREV_INSN (next) = prev;
2368 set_last_insn (prev);
2370 if (GET_CODE (insn) == CODE_LABEL)
2371 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
2373 /* If deleting a jump, decrement the use count of the label. Deleting
2374 the label itself should happen in the normal course of block merging. */
2375 if (GET_CODE (insn) == JUMP_INSN
2376 && JUMP_LABEL (insn)
2377 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
2378 LABEL_NUSES (JUMP_LABEL (insn))--;
2380 /* Also if deleting an insn that references a label. */
2381 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
2382 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
2383 LABEL_NUSES (XEXP (note, 0))--;
2388 /* True if a given label can be deleted. */
2391 can_delete_label_p (label)
2396 if (LABEL_PRESERVE_P (label))
2399 for (x = forced_labels; x; x = XEXP (x, 1))
2400 if (label == XEXP (x, 0))
2402 for (x = label_value_list; x; x = XEXP (x, 1))
2403 if (label == XEXP (x, 0))
2405 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2406 if (label == XEXP (x, 0))
2409 /* User declared labels must be preserved. */
2410 if (LABEL_NAME (label) != 0)
2417 tail_recursion_label_p (label)
2422 for (x = tail_recursion_label_list; x; x = XEXP (x, 1))
2423 if (label == XEXP (x, 0))
2429 /* Blocks A and B are to be merged into a single block A. The insns
2430 are already contiguous, hence `nomove'. */
2433 merge_blocks_nomove (a, b)
2437 rtx b_head, b_end, a_end;
2438 rtx del_first = NULL_RTX, del_last = NULL_RTX;
2441 /* If there was a CODE_LABEL beginning B, delete it. */
2444 if (GET_CODE (b_head) == CODE_LABEL)
2446 /* Detect basic blocks with nothing but a label. This can happen
2447 in particular at the end of a function. */
2448 if (b_head == b_end)
2450 del_first = del_last = b_head;
2451 b_head = NEXT_INSN (b_head);
2454 /* Delete the basic block note. */
2455 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
2457 if (b_head == b_end)
2462 b_head = NEXT_INSN (b_head);
2465 /* If there was a jump out of A, delete it. */
2467 if (GET_CODE (a_end) == JUMP_INSN)
2471 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
2472 if (GET_CODE (prev) != NOTE
2473 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
2480 /* If this was a conditional jump, we need to also delete
2481 the insn that set cc0. */
2482 if (prev && sets_cc0_p (prev))
2485 prev = prev_nonnote_insn (prev);
2494 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
2495 del_first = NEXT_INSN (a_end);
2497 /* Delete everything marked above as well as crap that might be
2498 hanging out between the two blocks. */
2499 flow_delete_insn_chain (del_first, del_last);
2501 /* Normally there should only be one successor of A and that is B, but
2502 partway though the merge of blocks for conditional_execution we'll
2503 be merging a TEST block with THEN and ELSE successors. Free the
2504 whole lot of them and hope the caller knows what they're doing. */
2506 remove_edge (a->succ);
2508 /* Adjust the edges out of B for the new owner. */
2509 for (e = b->succ; e; e = e->succ_next)
2513 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2514 b->pred = b->succ = NULL;
2516 /* Reassociate the insns of B with A. */
2519 if (basic_block_for_insn)
2521 BLOCK_FOR_INSN (b_head) = a;
2522 while (b_head != b_end)
2524 b_head = NEXT_INSN (b_head);
2525 BLOCK_FOR_INSN (b_head) = a;
2535 /* Blocks A and B are to be merged into a single block. A has no incoming
2536 fallthru edge, so it can be moved before B without adding or modifying
2537 any jumps (aside from the jump from A to B). */
2540 merge_blocks_move_predecessor_nojumps (a, b)
2543 rtx start, end, barrier;
2549 barrier = next_nonnote_insn (end);
2550 if (GET_CODE (barrier) != BARRIER)
2552 flow_delete_insn (barrier);
2554 /* Move block and loop notes out of the chain so that we do not
2555 disturb their order.
2557 ??? A better solution would be to squeeze out all the non-nested notes
2558 and adjust the block trees appropriately. Even better would be to have
2559 a tighter connection between block trees and rtl so that this is not
2561 start = squeeze_notes (start, end);
2563 /* Scramble the insn chain. */
2564 if (end != PREV_INSN (b->head))
2565 reorder_insns (start, end, PREV_INSN (b->head));
2569 fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n",
2570 a->index, b->index);
2573 /* Swap the records for the two blocks around. Although we are deleting B,
2574 A is now where B was and we want to compact the BB array from where
2576 BASIC_BLOCK (a->index) = b;
2577 BASIC_BLOCK (b->index) = a;
2579 a->index = b->index;
2582 /* Now blocks A and B are contiguous. Merge them. */
2583 merge_blocks_nomove (a, b);
2588 /* Blocks A and B are to be merged into a single block. B has no outgoing
2589 fallthru edge, so it can be moved after A without adding or modifying
2590 any jumps (aside from the jump from A to B). */
2593 merge_blocks_move_successor_nojumps (a, b)
2596 rtx start, end, barrier;
2600 barrier = NEXT_INSN (end);
2602 /* Recognize a jump table following block B. */
2603 if (GET_CODE (barrier) == CODE_LABEL
2604 && NEXT_INSN (barrier)
2605 && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN
2606 && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC
2607 || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC))
2609 end = NEXT_INSN (barrier);
2610 barrier = NEXT_INSN (end);
2613 /* There had better have been a barrier there. Delete it. */
2614 if (GET_CODE (barrier) != BARRIER)
2616 flow_delete_insn (barrier);
2618 /* Move block and loop notes out of the chain so that we do not
2619 disturb their order.
2621 ??? A better solution would be to squeeze out all the non-nested notes
2622 and adjust the block trees appropriately. Even better would be to have
2623 a tighter connection between block trees and rtl so that this is not
2625 start = squeeze_notes (start, end);
2627 /* Scramble the insn chain. */
2628 reorder_insns (start, end, a->end);
2630 /* Now blocks A and B are contiguous. Merge them. */
2631 merge_blocks_nomove (a, b);
2635 fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n",
2636 b->index, a->index);
2642 /* Attempt to merge basic blocks that are potentially non-adjacent.
2643 Return true iff the attempt succeeded. */
2646 merge_blocks (e, b, c)
2650 /* If C has a tail recursion label, do not merge. There is no
2651 edge recorded from the call_placeholder back to this label, as
2652 that would make optimize_sibling_and_tail_recursive_calls more
2653 complex for no gain. */
2654 if (GET_CODE (c->head) == CODE_LABEL
2655 && tail_recursion_label_p (c->head))
2658 /* If B has a fallthru edge to C, no need to move anything. */
2659 if (e->flags & EDGE_FALLTHRU)
2661 merge_blocks_nomove (b, c);
2665 fprintf (rtl_dump_file, "Merged %d and %d without moving.\n",
2666 b->index, c->index);
2675 int c_has_outgoing_fallthru;
2676 int b_has_incoming_fallthru;
2678 /* We must make sure to not munge nesting of exception regions,
2679 lexical blocks, and loop notes.
2681 The first is taken care of by requiring that the active eh
2682 region at the end of one block always matches the active eh
2683 region at the beginning of the next block.
2685 The later two are taken care of by squeezing out all the notes. */
2687 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2688 executed and we may want to treat blocks which have two out
2689 edges, one normal, one abnormal as only having one edge for
2690 block merging purposes. */
2692 for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next)
2693 if (tmp_edge->flags & EDGE_FALLTHRU)
2695 c_has_outgoing_fallthru = (tmp_edge != NULL);
2697 for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next)
2698 if (tmp_edge->flags & EDGE_FALLTHRU)
2700 b_has_incoming_fallthru = (tmp_edge != NULL);
2702 /* If B does not have an incoming fallthru, and the exception regions
2703 match, then it can be moved immediately before C without introducing
2706 C can not be the first block, so we do not have to worry about
2707 accessing a non-existent block. */
2708 d = BASIC_BLOCK (c->index - 1);
2709 if (! b_has_incoming_fallthru
2710 && d->eh_end == b->eh_beg
2711 && b->eh_end == c->eh_beg)
2712 return merge_blocks_move_predecessor_nojumps (b, c);
2714 /* Otherwise, we're going to try to move C after B. Make sure the
2715 exception regions match.
2717 If B is the last basic block, then we must not try to access the
2718 block structure for block B + 1. Luckily in that case we do not
2719 need to worry about matching exception regions. */
2720 d = (b->index + 1 < n_basic_blocks ? BASIC_BLOCK (b->index + 1) : NULL);
2721 if (b->eh_end == c->eh_beg
2722 && (d == NULL || c->eh_end == d->eh_beg))
2724 /* If C does not have an outgoing fallthru, then it can be moved
2725 immediately after B without introducing or modifying jumps. */
2726 if (! c_has_outgoing_fallthru)
2727 return merge_blocks_move_successor_nojumps (b, c);
2729 /* Otherwise, we'll need to insert an extra jump, and possibly
2730 a new block to contain it. */
2731 /* ??? Not implemented yet. */
2738 /* Top level driver for merge_blocks. */
2745 /* Attempt to merge blocks as made possible by edge removal. If a block
2746 has only one successor, and the successor has only one predecessor,
2747 they may be combined. */
2749 for (i = 0; i < n_basic_blocks;)
2751 basic_block c, b = BASIC_BLOCK (i);
2754 /* A loop because chains of blocks might be combineable. */
2755 while ((s = b->succ) != NULL
2756 && s->succ_next == NULL
2757 && (s->flags & EDGE_EH) == 0
2758 && (c = s->dest) != EXIT_BLOCK_PTR
2759 && c->pred->pred_next == NULL
2760 /* If the jump insn has side effects, we can't kill the edge. */
2761 && (GET_CODE (b->end) != JUMP_INSN
2762 || onlyjump_p (b->end))
2763 && merge_blocks (s, b, c))
2766 /* Don't get confused by the index shift caused by deleting blocks. */
2771 /* The given edge should potentially be a fallthru edge. If that is in
2772 fact true, delete the jump and barriers that are in the way. */
2775 tidy_fallthru_edge (e, b, c)
2781 /* ??? In a late-running flow pass, other folks may have deleted basic
2782 blocks by nopping out blocks, leaving multiple BARRIERs between here
2783 and the target label. They ought to be chastized and fixed.
2785 We can also wind up with a sequence of undeletable labels between
2786 one block and the next.
2788 So search through a sequence of barriers, labels, and notes for
2789 the head of block C and assert that we really do fall through. */
2791 if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head)))
2794 /* Remove what will soon cease being the jump insn from the source block.
2795 If block B consisted only of this single jump, turn it into a deleted
2798 if (GET_CODE (q) == JUMP_INSN
2800 && (any_uncondjump_p (q)
2801 || (b->succ == e && e->succ_next == NULL)))
2804 /* If this was a conditional jump, we need to also delete
2805 the insn that set cc0. */
2806 if (any_condjump_p (q) && sets_cc0_p (PREV_INSN (q)))
2813 NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
2814 NOTE_SOURCE_FILE (q) = 0;
2820 /* We don't want a block to end on a line-number note since that has
2821 the potential of changing the code between -g and not -g. */
2822 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
2829 /* Selectively unlink the sequence. */
2830 if (q != PREV_INSN (c->head))
2831 flow_delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
2833 e->flags |= EDGE_FALLTHRU;
2836 /* Fix up edges that now fall through, or rather should now fall through
2837 but previously required a jump around now deleted blocks. Simplify
2838 the search by only examining blocks numerically adjacent, since this
2839 is how find_basic_blocks created them. */
2842 tidy_fallthru_edges ()
2846 for (i = 1; i < n_basic_blocks; ++i)
2848 basic_block b = BASIC_BLOCK (i - 1);
2849 basic_block c = BASIC_BLOCK (i);
2852 /* We care about simple conditional or unconditional jumps with
2855 If we had a conditional branch to the next instruction when
2856 find_basic_blocks was called, then there will only be one
2857 out edge for the block which ended with the conditional
2858 branch (since we do not create duplicate edges).
2860 Furthermore, the edge will be marked as a fallthru because we
2861 merge the flags for the duplicate edges. So we do not want to
2862 check that the edge is not a FALLTHRU edge. */
2863 if ((s = b->succ) != NULL
2864 && s->succ_next == NULL
2866 /* If the jump insn has side effects, we can't tidy the edge. */
2867 && (GET_CODE (b->end) != JUMP_INSN
2868 || onlyjump_p (b->end)))
2869 tidy_fallthru_edge (s, b, c);
2873 /* Perform data flow analysis.
2874 F is the first insn of the function; FLAGS is a set of PROP_* flags
2875 to be used in accumulating flow info. */
2878 life_analysis (f, file, flags)
2883 #ifdef ELIMINABLE_REGS
2885 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
2888 /* Record which registers will be eliminated. We use this in
2891 CLEAR_HARD_REG_SET (elim_reg_set);
2893 #ifdef ELIMINABLE_REGS
2894 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
2895 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
2897 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
2901 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC);
2903 /* The post-reload life analysis have (on a global basis) the same
2904 registers live as was computed by reload itself. elimination
2905 Otherwise offsets and such may be incorrect.
2907 Reload will make some registers as live even though they do not
2910 We don't want to create new auto-incs after reload, since they
2911 are unlikely to be useful and can cause problems with shared
2913 if (reload_completed)
2914 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
2916 /* We want alias analysis information for local dead store elimination. */
2917 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2918 init_alias_analysis ();
2920 /* Always remove no-op moves. Do this before other processing so
2921 that we don't have to keep re-scanning them. */
2922 delete_noop_moves (f);
2924 /* Some targets can emit simpler epilogues if they know that sp was
2925 not ever modified during the function. After reload, of course,
2926 we've already emitted the epilogue so there's no sense searching. */
2927 if (! reload_completed)
2928 notice_stack_pointer_modification (f);
2930 /* Allocate and zero out data structures that will record the
2931 data from lifetime analysis. */
2932 allocate_reg_life_data ();
2933 allocate_bb_life_data ();
2935 /* Find the set of registers live on function exit. */
2936 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
2938 /* "Update" life info from zero. It'd be nice to begin the
2939 relaxation with just the exit and noreturn blocks, but that set
2940 is not immediately handy. */
2942 if (flags & PROP_REG_INFO)
2943 memset (regs_ever_live, 0, sizeof (regs_ever_live));
2944 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
2947 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2948 end_alias_analysis ();
2951 dump_flow_info (file);
2953 free_basic_block_vars (1);
2956 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2957 Search for REGNO. If found, abort if it is not wider than word_mode. */
2960 verify_wide_reg_1 (px, pregno)
2965 unsigned int regno = *(int *) pregno;
2967 if (GET_CODE (x) == REG && REGNO (x) == regno)
2969 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
2976 /* A subroutine of verify_local_live_at_start. Search through insns
2977 between HEAD and END looking for register REGNO. */
2980 verify_wide_reg (regno, head, end)
2987 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
2991 head = NEXT_INSN (head);
2994 /* We didn't find the register at all. Something's way screwy. */
2996 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
2997 print_rtl_and_abort ();
3000 /* A subroutine of update_life_info. Verify that there are no untoward
3001 changes in live_at_start during a local update. */
3004 verify_local_live_at_start (new_live_at_start, bb)
3005 regset new_live_at_start;
3008 if (reload_completed)
3010 /* After reload, there are no pseudos, nor subregs of multi-word
3011 registers. The regsets should exactly match. */
3012 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
3016 fprintf (rtl_dump_file,
3017 "live_at_start mismatch in bb %d, aborting\n",
3019 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
3020 debug_bitmap_file (rtl_dump_file, new_live_at_start);
3022 print_rtl_and_abort ();
3029 /* Find the set of changed registers. */
3030 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
3032 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
3034 /* No registers should die. */
3035 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
3038 fprintf (rtl_dump_file,
3039 "Register %d died unexpectedly in block %d\n", i,
3041 print_rtl_and_abort ();
3044 /* Verify that the now-live register is wider than word_mode. */
3045 verify_wide_reg (i, bb->head, bb->end);
3050 /* Updates life information starting with the basic blocks set in BLOCKS.
3051 If BLOCKS is null, consider it to be the universal set.
3053 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
3054 we are only expecting local modifications to basic blocks. If we find
3055 extra registers live at the beginning of a block, then we either killed
3056 useful data, or we have a broken split that wants data not provided.
3057 If we find registers removed from live_at_start, that means we have
3058 a broken peephole that is killing a register it shouldn't.
3060 ??? This is not true in one situation -- when a pre-reload splitter
3061 generates subregs of a multi-word pseudo, current life analysis will
3062 lose the kill. So we _can_ have a pseudo go live. How irritating.
3064 Including PROP_REG_INFO does not properly refresh regs_ever_live
3065 unless the caller resets it to zero. */
3068 update_life_info (blocks, extent, prop_flags)
3070 enum update_life_extent extent;
3074 regset_head tmp_head;
3077 tmp = INITIALIZE_REG_SET (tmp_head);
3079 /* For a global update, we go through the relaxation process again. */
3080 if (extent != UPDATE_LIFE_LOCAL)
3082 calculate_global_regs_live (blocks, blocks,
3083 prop_flags & PROP_SCAN_DEAD_CODE);
3085 /* If asked, remove notes from the blocks we'll update. */
3086 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
3087 count_or_remove_death_notes (blocks, 1);
3092 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
3094 basic_block bb = BASIC_BLOCK (i);
3096 COPY_REG_SET (tmp, bb->global_live_at_end);
3097 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3099 if (extent == UPDATE_LIFE_LOCAL)
3100 verify_local_live_at_start (tmp, bb);
3105 for (i = n_basic_blocks - 1; i >= 0; --i)
3107 basic_block bb = BASIC_BLOCK (i);
3109 COPY_REG_SET (tmp, bb->global_live_at_end);
3110 propagate_block (bb, tmp, NULL, NULL, prop_flags);
3112 if (extent == UPDATE_LIFE_LOCAL)
3113 verify_local_live_at_start (tmp, bb);
3119 if (prop_flags & PROP_REG_INFO)
3121 /* The only pseudos that are live at the beginning of the function
3122 are those that were not set anywhere in the function. local-alloc
3123 doesn't know how to handle these correctly, so mark them as not
3124 local to any one basic block. */
3125 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
3126 FIRST_PSEUDO_REGISTER, i,
3127 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
3129 /* We have a problem with any pseudoreg that lives across the setjmp.
3130 ANSI says that if a user variable does not change in value between
3131 the setjmp and the longjmp, then the longjmp preserves it. This
3132 includes longjmp from a place where the pseudo appears dead.
3133 (In principle, the value still exists if it is in scope.)
3134 If the pseudo goes in a hard reg, some other value may occupy
3135 that hard reg where this pseudo is dead, thus clobbering the pseudo.
3136 Conclusion: such a pseudo must not go in a hard reg. */
3137 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
3138 FIRST_PSEUDO_REGISTER, i,
3140 if (regno_reg_rtx[i] != 0)
3142 REG_LIVE_LENGTH (i) = -1;
3143 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3149 /* Free the variables allocated by find_basic_blocks.
3151 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
3154 free_basic_block_vars (keep_head_end_p)
3155 int keep_head_end_p;
3157 if (basic_block_for_insn)
3159 VARRAY_FREE (basic_block_for_insn);
3160 basic_block_for_insn = NULL;
3163 if (! keep_head_end_p)
3166 VARRAY_FREE (basic_block_info);
3169 ENTRY_BLOCK_PTR->aux = NULL;
3170 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
3171 EXIT_BLOCK_PTR->aux = NULL;
3172 EXIT_BLOCK_PTR->global_live_at_start = NULL;
3176 /* Return nonzero if the destination of SET equals the source. */
3182 rtx src = SET_SRC (set);
3183 rtx dst = SET_DEST (set);
3185 if (GET_CODE (src) == SUBREG && GET_CODE (dst) == SUBREG)
3187 if (SUBREG_WORD (src) != SUBREG_WORD (dst))
3189 src = SUBREG_REG (src);
3190 dst = SUBREG_REG (dst);
3193 return (GET_CODE (src) == REG && GET_CODE (dst) == REG
3194 && REGNO (src) == REGNO (dst));
3197 /* Return nonzero if an insn consists only of SETs, each of which only sets a
3204 rtx pat = PATTERN (insn);
3206 /* Insns carrying these notes are useful later on. */
3207 if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
3210 if (GET_CODE (pat) == SET && set_noop_p (pat))
3213 if (GET_CODE (pat) == PARALLEL)
3216 /* If nothing but SETs of registers to themselves,
3217 this insn can also be deleted. */
3218 for (i = 0; i < XVECLEN (pat, 0); i++)
3220 rtx tem = XVECEXP (pat, 0, i);
3222 if (GET_CODE (tem) == USE
3223 || GET_CODE (tem) == CLOBBER)
3226 if (GET_CODE (tem) != SET || ! set_noop_p (tem))
3235 /* Delete any insns that copy a register to itself. */
3238 delete_noop_moves (f)
3242 for (insn = f; insn; insn = NEXT_INSN (insn))
3244 if (GET_CODE (insn) == INSN && noop_move_p (insn))
3246 PUT_CODE (insn, NOTE);
3247 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
3248 NOTE_SOURCE_FILE (insn) = 0;
3253 /* Determine if the stack pointer is constant over the life of the function.
3254 Only useful before prologues have been emitted. */
3257 notice_stack_pointer_modification_1 (x, pat, data)
3259 rtx pat ATTRIBUTE_UNUSED;
3260 void *data ATTRIBUTE_UNUSED;
3262 if (x == stack_pointer_rtx
3263 /* The stack pointer is only modified indirectly as the result
3264 of a push until later in flow. See the comments in rtl.texi
3265 regarding Embedded Side-Effects on Addresses. */
3266 || (GET_CODE (x) == MEM
3267 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
3268 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
3269 current_function_sp_is_unchanging = 0;
3273 notice_stack_pointer_modification (f)
3278 /* Assume that the stack pointer is unchanging if alloca hasn't
3280 current_function_sp_is_unchanging = !current_function_calls_alloca;
3281 if (! current_function_sp_is_unchanging)
3284 for (insn = f; insn; insn = NEXT_INSN (insn))
3288 /* Check if insn modifies the stack pointer. */
3289 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
3291 if (! current_function_sp_is_unchanging)
3297 /* Mark a register in SET. Hard registers in large modes get all
3298 of their component registers set as well. */
3301 mark_reg (reg, xset)
3305 regset set = (regset) xset;
3306 int regno = REGNO (reg);
3308 if (GET_MODE (reg) == BLKmode)
3311 SET_REGNO_REG_SET (set, regno);
3312 if (regno < FIRST_PSEUDO_REGISTER)
3314 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
3316 SET_REGNO_REG_SET (set, regno + n);
3320 /* Mark those regs which are needed at the end of the function as live
3321 at the end of the last basic block. */
3324 mark_regs_live_at_end (set)
3329 /* If exiting needs the right stack value, consider the stack pointer
3330 live at the end of the function. */
3331 if ((HAVE_epilogue && reload_completed)
3332 || ! EXIT_IGNORE_STACK
3333 || (! FRAME_POINTER_REQUIRED
3334 && ! current_function_calls_alloca
3335 && flag_omit_frame_pointer)
3336 || current_function_sp_is_unchanging)
3338 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
3341 /* Mark the frame pointer if needed at the end of the function. If
3342 we end up eliminating it, it will be removed from the live list
3343 of each basic block by reload. */
3345 if (! reload_completed || frame_pointer_needed)
3347 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
3348 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3349 /* If they are different, also mark the hard frame pointer as live. */
3350 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
3351 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
3355 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
3356 /* Many architectures have a GP register even without flag_pic.
3357 Assume the pic register is not in use, or will be handled by
3358 other means, if it is not fixed. */
3359 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3360 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3361 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
3364 /* Mark all global registers, and all registers used by the epilogue
3365 as being live at the end of the function since they may be
3366 referenced by our caller. */
3367 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3368 if (global_regs[i] || EPILOGUE_USES (i))
3369 SET_REGNO_REG_SET (set, i);
3371 /* Mark all call-saved registers that we actaully used. */
3372 if (HAVE_epilogue && reload_completed)
3374 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3375 if (regs_ever_live[i] && ! call_used_regs[i] && ! LOCAL_REGNO (i))
3376 SET_REGNO_REG_SET (set, i);
3379 /* Mark function return value. */
3380 diddle_return_value (mark_reg, set);
3383 /* Callback function for for_each_successor_phi. DATA is a regset.
3384 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3385 INSN, in the regset. */
3388 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
3389 rtx insn ATTRIBUTE_UNUSED;
3390 int dest_regno ATTRIBUTE_UNUSED;
3394 regset live = (regset) data;
3395 SET_REGNO_REG_SET (live, src_regno);
3399 /* Propagate global life info around the graph of basic blocks. Begin
3400 considering blocks with their corresponding bit set in BLOCKS_IN.
3401 If BLOCKS_IN is null, consider it the universal set.
3403 BLOCKS_OUT is set for every block that was changed. */
3406 calculate_global_regs_live (blocks_in, blocks_out, flags)
3407 sbitmap blocks_in, blocks_out;
3410 basic_block *queue, *qhead, *qtail, *qend;
3411 regset tmp, new_live_at_end;
3412 regset_head tmp_head;
3413 regset_head new_live_at_end_head;
3416 tmp = INITIALIZE_REG_SET (tmp_head);
3417 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
3419 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3420 because the `head == tail' style test for an empty queue doesn't
3421 work with a full queue. */
3422 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
3424 qhead = qend = queue + n_basic_blocks + 2;
3426 /* Queue the blocks set in the initial mask. Do this in reverse block
3427 number order so that we are more likely for the first round to do
3428 useful work. We use AUX non-null to flag that the block is queued. */
3431 /* Clear out the garbage that might be hanging out in bb->aux. */
3432 for (i = n_basic_blocks - 1; i >= 0; --i)
3433 BASIC_BLOCK (i)->aux = NULL;
3435 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
3437 basic_block bb = BASIC_BLOCK (i);
3444 for (i = 0; i < n_basic_blocks; ++i)
3446 basic_block bb = BASIC_BLOCK (i);
3453 sbitmap_zero (blocks_out);
3455 while (qhead != qtail)
3457 int rescan, changed;
3466 /* Begin by propogating live_at_start from the successor blocks. */
3467 CLEAR_REG_SET (new_live_at_end);
3468 for (e = bb->succ; e; e = e->succ_next)
3470 basic_block sb = e->dest;
3471 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
3474 /* The all-important stack pointer must always be live. */
3475 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
3477 /* Before reload, there are a few registers that must be forced
3478 live everywhere -- which might not already be the case for
3479 blocks within infinite loops. */
3480 if (! reload_completed)
3482 /* Any reference to any pseudo before reload is a potential
3483 reference of the frame pointer. */
3484 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
3486 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3487 /* Pseudos with argument area equivalences may require
3488 reloading via the argument pointer. */
3489 if (fixed_regs[ARG_POINTER_REGNUM])
3490 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
3493 /* Any constant, or pseudo with constant equivalences, may
3494 require reloading from memory using the pic register. */
3495 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
3496 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
3497 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
3500 /* Regs used in phi nodes are not included in
3501 global_live_at_start, since they are live only along a
3502 particular edge. Set those regs that are live because of a
3503 phi node alternative corresponding to this particular block. */
3505 for_each_successor_phi (bb, &set_phi_alternative_reg,
3508 if (bb == ENTRY_BLOCK_PTR)
3510 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3514 /* On our first pass through this block, we'll go ahead and continue.
3515 Recognize first pass by local_set NULL. On subsequent passes, we
3516 get to skip out early if live_at_end wouldn't have changed. */
3518 if (bb->local_set == NULL)
3520 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3521 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3526 /* If any bits were removed from live_at_end, we'll have to
3527 rescan the block. This wouldn't be necessary if we had
3528 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3529 local_live is really dependent on live_at_end. */
3530 CLEAR_REG_SET (tmp);
3531 rescan = bitmap_operation (tmp, bb->global_live_at_end,
3532 new_live_at_end, BITMAP_AND_COMPL);
3536 /* If any of the registers in the new live_at_end set are
3537 conditionally set in this basic block, we must rescan.
3538 This is because conditional lifetimes at the end of the
3539 block do not just take the live_at_end set into account,
3540 but also the liveness at the start of each successor
3541 block. We can miss changes in those sets if we only
3542 compare the new live_at_end against the previous one. */
3543 CLEAR_REG_SET (tmp);
3544 rescan = bitmap_operation (tmp, new_live_at_end,
3545 bb->cond_local_set, BITMAP_AND);
3550 /* Find the set of changed bits. Take this opportunity
3551 to notice that this set is empty and early out. */
3552 CLEAR_REG_SET (tmp);
3553 changed = bitmap_operation (tmp, bb->global_live_at_end,
3554 new_live_at_end, BITMAP_XOR);
3558 /* If any of the changed bits overlap with local_set,
3559 we'll have to rescan the block. Detect overlap by
3560 the AND with ~local_set turning off bits. */
3561 rescan = bitmap_operation (tmp, tmp, bb->local_set,
3566 /* Let our caller know that BB changed enough to require its
3567 death notes updated. */
3569 SET_BIT (blocks_out, bb->index);
3573 /* Add to live_at_start the set of all registers in
3574 new_live_at_end that aren't in the old live_at_end. */
3576 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
3578 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3580 changed = bitmap_operation (bb->global_live_at_start,
3581 bb->global_live_at_start,
3588 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
3590 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3591 into live_at_start. */
3592 propagate_block (bb, new_live_at_end, bb->local_set,
3593 bb->cond_local_set, flags);
3595 /* If live_at start didn't change, no need to go farther. */
3596 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
3599 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
3602 /* Queue all predecessors of BB so that we may re-examine
3603 their live_at_end. */
3604 for (e = bb->pred; e; e = e->pred_next)
3606 basic_block pb = e->src;
3607 if (pb->aux == NULL)
3618 FREE_REG_SET (new_live_at_end);
3622 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
3624 basic_block bb = BASIC_BLOCK (i);
3625 FREE_REG_SET (bb->local_set);
3626 FREE_REG_SET (bb->cond_local_set);
3631 for (i = n_basic_blocks - 1; i >= 0; --i)
3633 basic_block bb = BASIC_BLOCK (i);
3634 FREE_REG_SET (bb->local_set);
3635 FREE_REG_SET (bb->cond_local_set);
3642 /* Subroutines of life analysis. */
3644 /* Allocate the permanent data structures that represent the results
3645 of life analysis. Not static since used also for stupid life analysis. */
3648 allocate_bb_life_data ()
3652 for (i = 0; i < n_basic_blocks; i++)
3654 basic_block bb = BASIC_BLOCK (i);
3656 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3657 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3660 ENTRY_BLOCK_PTR->global_live_at_end
3661 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3662 EXIT_BLOCK_PTR->global_live_at_start
3663 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3665 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
3669 allocate_reg_life_data ()
3673 max_regno = max_reg_num ();
3675 /* Recalculate the register space, in case it has grown. Old style
3676 vector oriented regsets would set regset_{size,bytes} here also. */
3677 allocate_reg_info (max_regno, FALSE, FALSE);
3679 /* Reset all the data we'll collect in propagate_block and its
3681 for (i = 0; i < max_regno; i++)
3685 REG_N_DEATHS (i) = 0;
3686 REG_N_CALLS_CROSSED (i) = 0;
3687 REG_LIVE_LENGTH (i) = 0;
3688 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
3692 /* Delete dead instructions for propagate_block. */
3695 propagate_block_delete_insn (bb, insn)
3699 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
3701 /* If the insn referred to a label, and that label was attached to
3702 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3703 pretty much mandatory to delete it, because the ADDR_VEC may be
3704 referencing labels that no longer exist. */
3708 rtx label = XEXP (inote, 0);
3711 if (LABEL_NUSES (label) == 1
3712 && (next = next_nonnote_insn (label)) != NULL
3713 && GET_CODE (next) == JUMP_INSN
3714 && (GET_CODE (PATTERN (next)) == ADDR_VEC
3715 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
3717 rtx pat = PATTERN (next);
3718 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
3719 int len = XVECLEN (pat, diff_vec_p);
3722 for (i = 0; i < len; i++)
3723 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
3725 flow_delete_insn (next);
3729 if (bb->end == insn)
3730 bb->end = PREV_INSN (insn);
3731 flow_delete_insn (insn);
3734 /* Delete dead libcalls for propagate_block. Return the insn
3735 before the libcall. */
3738 propagate_block_delete_libcall (bb, insn, note)
3742 rtx first = XEXP (note, 0);
3743 rtx before = PREV_INSN (first);
3745 if (insn == bb->end)
3748 flow_delete_insn_chain (first, insn);
3752 /* Update the life-status of regs for one insn. Return the previous insn. */
3755 propagate_one_insn (pbi, insn)
3756 struct propagate_block_info *pbi;
3759 rtx prev = PREV_INSN (insn);
3760 int flags = pbi->flags;
3761 int insn_is_dead = 0;
3762 int libcall_is_dead = 0;
3766 if (! INSN_P (insn))
3769 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3770 if (flags & PROP_SCAN_DEAD_CODE)
3772 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
3773 libcall_is_dead = (insn_is_dead && note != 0
3774 && libcall_dead_p (pbi, note, insn));
3777 /* If an instruction consists of just dead store(s) on final pass,
3779 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
3781 /* If we're trying to delete a prologue or epilogue instruction
3782 that isn't flagged as possibly being dead, something is wrong.
3783 But if we are keeping the stack pointer depressed, we might well
3784 be deleting insns that are used to compute the amount to update
3785 it by, so they are fine. */
3786 if (reload_completed
3787 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
3788 && (TYPE_RETURNS_STACK_DEPRESSED
3789 (TREE_TYPE (current_function_decl))))
3790 && (((HAVE_epilogue || HAVE_prologue)
3791 && prologue_epilogue_contains (insn))
3792 || (HAVE_sibcall_epilogue
3793 && sibcall_epilogue_contains (insn)))
3794 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
3797 /* Record sets. Do this even for dead instructions, since they
3798 would have killed the values if they hadn't been deleted. */
3799 mark_set_regs (pbi, PATTERN (insn), insn);
3801 /* CC0 is now known to be dead. Either this insn used it,
3802 in which case it doesn't anymore, or clobbered it,
3803 so the next insn can't use it. */
3806 if (libcall_is_dead)
3808 prev = propagate_block_delete_libcall (pbi->bb, insn, note);
3809 insn = NEXT_INSN (prev);
3812 propagate_block_delete_insn (pbi->bb, insn);
3817 /* See if this is an increment or decrement that can be merged into
3818 a following memory address. */
3821 register rtx x = single_set (insn);
3823 /* Does this instruction increment or decrement a register? */
3824 if ((flags & PROP_AUTOINC)
3826 && GET_CODE (SET_DEST (x)) == REG
3827 && (GET_CODE (SET_SRC (x)) == PLUS
3828 || GET_CODE (SET_SRC (x)) == MINUS)
3829 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
3830 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
3831 /* Ok, look for a following memory ref we can combine with.
3832 If one is found, change the memory ref to a PRE_INC
3833 or PRE_DEC, cancel this insn, and return 1.
3834 Return 0 if nothing has been done. */
3835 && try_pre_increment_1 (pbi, insn))
3838 #endif /* AUTO_INC_DEC */
3840 CLEAR_REG_SET (pbi->new_set);
3842 /* If this is not the final pass, and this insn is copying the value of
3843 a library call and it's dead, don't scan the insns that perform the
3844 library call, so that the call's arguments are not marked live. */
3845 if (libcall_is_dead)
3847 /* Record the death of the dest reg. */
3848 mark_set_regs (pbi, PATTERN (insn), insn);
3850 insn = XEXP (note, 0);
3851 return PREV_INSN (insn);
3853 else if (GET_CODE (PATTERN (insn)) == SET
3854 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
3855 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
3856 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
3857 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
3858 /* We have an insn to pop a constant amount off the stack.
3859 (Such insns use PLUS regardless of the direction of the stack,
3860 and any insn to adjust the stack by a constant is always a pop.)
3861 These insns, if not dead stores, have no effect on life. */
3865 /* Any regs live at the time of a call instruction must not go
3866 in a register clobbered by calls. Find all regs now live and
3867 record this for them. */
3869 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
3870 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3871 { REG_N_CALLS_CROSSED (i)++; });
3873 /* Record sets. Do this even for dead instructions, since they
3874 would have killed the values if they hadn't been deleted. */
3875 mark_set_regs (pbi, PATTERN (insn), insn);
3877 if (GET_CODE (insn) == CALL_INSN)
3883 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3884 cond = COND_EXEC_TEST (PATTERN (insn));
3886 /* Non-constant calls clobber memory. */
3887 if (! CONST_CALL_P (insn))
3889 free_EXPR_LIST_list (&pbi->mem_set_list);
3890 pbi->mem_set_list_len = 0;
3893 /* There may be extra registers to be clobbered. */
3894 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3896 note = XEXP (note, 1))
3897 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
3898 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
3899 cond, insn, pbi->flags);
3901 /* Calls change all call-used and global registers. */
3902 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3903 if (call_used_regs[i] && ! global_regs[i]
3906 /* We do not want REG_UNUSED notes for these registers. */
3907 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
3909 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
3913 /* If an insn doesn't use CC0, it becomes dead since we assume
3914 that every insn clobbers it. So show it dead here;
3915 mark_used_regs will set it live if it is referenced. */
3920 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
3922 /* Sometimes we may have inserted something before INSN (such as a move)
3923 when we make an auto-inc. So ensure we will scan those insns. */
3925 prev = PREV_INSN (insn);
3928 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
3934 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
3935 cond = COND_EXEC_TEST (PATTERN (insn));
3937 /* Calls use their arguments. */
3938 for (note = CALL_INSN_FUNCTION_USAGE (insn);
3940 note = XEXP (note, 1))
3941 if (GET_CODE (XEXP (note, 0)) == USE)
3942 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
3945 /* The stack ptr is used (honorarily) by a CALL insn. */
3946 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
3948 /* Calls may also reference any of the global registers,
3949 so they are made live. */
3950 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
3952 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
3957 /* On final pass, update counts of how many insns in which each reg
3959 if (flags & PROP_REG_INFO)
3960 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
3961 { REG_LIVE_LENGTH (i)++; });
3966 /* Initialize a propagate_block_info struct for public consumption.
3967 Note that the structure itself is opaque to this file, but that
3968 the user can use the regsets provided here. */
3970 struct propagate_block_info *
3971 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
3973 regset live, local_set, cond_local_set;
3976 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
3979 pbi->reg_live = live;
3980 pbi->mem_set_list = NULL_RTX;
3981 pbi->mem_set_list_len = 0;
3982 pbi->local_set = local_set;
3983 pbi->cond_local_set = cond_local_set;
3987 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3988 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
3990 pbi->reg_next_use = NULL;
3992 pbi->new_set = BITMAP_XMALLOC ();
3994 #ifdef HAVE_conditional_execution
3995 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
3996 free_reg_cond_life_info);
3997 pbi->reg_cond_reg = BITMAP_XMALLOC ();
3999 /* If this block ends in a conditional branch, for each register live
4000 from one side of the branch and not the other, record the register
4001 as conditionally dead. */
4002 if (GET_CODE (bb->end) == JUMP_INSN
4003 && any_condjump_p (bb->end))
4005 regset_head diff_head;
4006 regset diff = INITIALIZE_REG_SET (diff_head);
4007 basic_block bb_true, bb_false;
4008 rtx cond_true, cond_false, set_src;
4011 /* Identify the successor blocks. */
4012 bb_true = bb->succ->dest;
4013 if (bb->succ->succ_next != NULL)
4015 bb_false = bb->succ->succ_next->dest;
4017 if (bb->succ->flags & EDGE_FALLTHRU)
4019 basic_block t = bb_false;
4023 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
4028 /* This can happen with a conditional jump to the next insn. */
4029 if (JUMP_LABEL (bb->end) != bb_true->head)
4032 /* Simplest way to do nothing. */
4036 /* Extract the condition from the branch. */
4037 set_src = SET_SRC (pc_set (bb->end));
4038 cond_true = XEXP (set_src, 0);
4039 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
4040 GET_MODE (cond_true), XEXP (cond_true, 0),
4041 XEXP (cond_true, 1));
4042 if (GET_CODE (XEXP (set_src, 1)) == PC)
4045 cond_false = cond_true;
4049 /* Compute which register lead different lives in the successors. */
4050 if (bitmap_operation (diff, bb_true->global_live_at_start,
4051 bb_false->global_live_at_start, BITMAP_XOR))
4053 rtx reg = XEXP (cond_true, 0);
4055 if (GET_CODE (reg) == SUBREG)
4056 reg = SUBREG_REG (reg);
4058 if (GET_CODE (reg) != REG)
4061 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
4063 /* For each such register, mark it conditionally dead. */
4064 EXECUTE_IF_SET_IN_REG_SET
4067 struct reg_cond_life_info *rcli;
4070 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
4072 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
4076 rcli->condition = cond;
4078 splay_tree_insert (pbi->reg_cond_dead, i,
4079 (splay_tree_value) rcli);
4083 FREE_REG_SET (diff);
4087 /* If this block has no successors, any stores to the frame that aren't
4088 used later in the block are dead. So make a pass over the block
4089 recording any such that are made and show them dead at the end. We do
4090 a very conservative and simple job here. */
4092 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
4093 && (TYPE_RETURNS_STACK_DEPRESSED
4094 (TREE_TYPE (current_function_decl))))
4095 && (flags & PROP_SCAN_DEAD_CODE)
4096 && (bb->succ == NULL
4097 || (bb->succ->succ_next == NULL
4098 && bb->succ->dest == EXIT_BLOCK_PTR)))
4101 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
4102 if (GET_CODE (insn) == INSN
4103 && GET_CODE (PATTERN (insn)) == SET
4104 && GET_CODE (SET_DEST (PATTERN (insn))) == MEM)
4106 rtx mem = SET_DEST (PATTERN (insn));
4108 /* This optimization is performed by faking a store to the
4109 memory at the end of the block. This doesn't work for
4110 unchanging memories because multiple stores to unchanging
4111 memory is illegal and alias analysis doesn't consider it. */
4112 if (RTX_UNCHANGING_P (mem))
4115 if (XEXP (mem, 0) == frame_pointer_rtx
4116 || (GET_CODE (XEXP (mem, 0)) == PLUS
4117 && XEXP (XEXP (mem, 0), 0) == frame_pointer_rtx
4118 && GET_CODE (XEXP (XEXP (mem, 0), 1)) == CONST_INT))
4121 /* Store a copy of mem, otherwise the address may be scrogged
4122 by find_auto_inc. This matters because insn_dead_p uses
4123 an rtx_equal_p check to determine if two addresses are
4124 the same. This works before find_auto_inc, but fails
4125 after find_auto_inc, causing discrepencies between the
4126 set of live registers calculated during the
4127 calculate_global_regs_live phase and what actually exists
4128 after flow completes, leading to aborts. */
4129 if (flags & PROP_AUTOINC)
4130 mem = shallow_copy_rtx (mem);
4132 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
4133 if (++pbi->mem_set_list_len >= MAX_MEM_SET_LIST_LEN)
4142 /* Release a propagate_block_info struct. */
4145 free_propagate_block_info (pbi)
4146 struct propagate_block_info *pbi;
4148 free_EXPR_LIST_list (&pbi->mem_set_list);
4150 BITMAP_XFREE (pbi->new_set);
4152 #ifdef HAVE_conditional_execution
4153 splay_tree_delete (pbi->reg_cond_dead);
4154 BITMAP_XFREE (pbi->reg_cond_reg);
4157 if (pbi->reg_next_use)
4158 free (pbi->reg_next_use);
4163 /* Compute the registers live at the beginning of a basic block BB from
4164 those live at the end.
4166 When called, REG_LIVE contains those live at the end. On return, it
4167 contains those live at the beginning.
4169 LOCAL_SET, if non-null, will be set with all registers killed
4170 unconditionally by this basic block.
4171 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
4172 killed conditionally by this basic block. If there is any unconditional
4173 set of a register, then the corresponding bit will be set in LOCAL_SET
4174 and cleared in COND_LOCAL_SET.
4175 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
4176 case, the resulting set will be equal to the union of the two sets that
4177 would otherwise be computed. */
4180 propagate_block (bb, live, local_set, cond_local_set, flags)
4184 regset cond_local_set;
4187 struct propagate_block_info *pbi;
4190 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
4192 if (flags & PROP_REG_INFO)
4196 /* Process the regs live at the end of the block.
4197 Mark them as not local to any one basic block. */
4198 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
4199 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
4202 /* Scan the block an insn at a time from end to beginning. */
4204 for (insn = bb->end;; insn = prev)
4206 /* If this is a call to `setjmp' et al, warn if any
4207 non-volatile datum is live. */
4208 if ((flags & PROP_REG_INFO)
4209 && GET_CODE (insn) == NOTE
4210 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
4211 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
4213 prev = propagate_one_insn (pbi, insn);
4215 if (insn == bb->head)
4219 free_propagate_block_info (pbi);
4222 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
4223 (SET expressions whose destinations are registers dead after the insn).
4224 NEEDED is the regset that says which regs are alive after the insn.
4226 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
4228 If X is the entire body of an insn, NOTES contains the reg notes
4229 pertaining to the insn. */
4232 insn_dead_p (pbi, x, call_ok, notes)
4233 struct propagate_block_info *pbi;
4236 rtx notes ATTRIBUTE_UNUSED;
4238 enum rtx_code code = GET_CODE (x);
4241 /* If flow is invoked after reload, we must take existing AUTO_INC
4242 expresions into account. */
4243 if (reload_completed)
4245 for (; notes; notes = XEXP (notes, 1))
4247 if (REG_NOTE_KIND (notes) == REG_INC)
4249 int regno = REGNO (XEXP (notes, 0));
4251 /* Don't delete insns to set global regs. */
4252 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4253 || REGNO_REG_SET_P (pbi->reg_live, regno))
4260 /* If setting something that's a reg or part of one,
4261 see if that register's altered value will be live. */
4265 rtx r = SET_DEST (x);
4268 if (GET_CODE (r) == CC0)
4269 return ! pbi->cc0_live;
4272 /* A SET that is a subroutine call cannot be dead. */
4273 if (GET_CODE (SET_SRC (x)) == CALL)
4279 /* Don't eliminate loads from volatile memory or volatile asms. */
4280 else if (volatile_refs_p (SET_SRC (x)))
4283 if (GET_CODE (r) == MEM)
4287 if (MEM_VOLATILE_P (r))
4290 /* Walk the set of memory locations we are currently tracking
4291 and see if one is an identical match to this memory location.
4292 If so, this memory write is dead (remember, we're walking
4293 backwards from the end of the block to the start). */
4294 temp = pbi->mem_set_list;
4297 rtx mem = XEXP (temp, 0);
4299 if (rtx_equal_p (mem, r))
4302 /* Check if memory reference matches an auto increment. Only
4303 post increment/decrement or modify are valid. */
4304 if (GET_MODE (mem) == GET_MODE (r)
4305 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
4306 || GET_CODE (XEXP (mem, 0)) == POST_INC
4307 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
4308 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
4309 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
4312 temp = XEXP (temp, 1);
4317 while (GET_CODE (r) == SUBREG
4318 || GET_CODE (r) == STRICT_LOW_PART
4319 || GET_CODE (r) == ZERO_EXTRACT)
4322 if (GET_CODE (r) == REG)
4324 int regno = REGNO (r);
4327 if (REGNO_REG_SET_P (pbi->reg_live, regno))
4330 /* If this is a hard register, verify that subsequent
4331 words are not needed. */
4332 if (regno < FIRST_PSEUDO_REGISTER)
4334 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
4337 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
4341 /* Don't delete insns to set global regs. */
4342 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
4345 /* Make sure insns to set the stack pointer aren't deleted. */
4346 if (regno == STACK_POINTER_REGNUM)
4349 /* ??? These bits might be redundant with the force live bits
4350 in calculate_global_regs_live. We would delete from
4351 sequential sets; whether this actually affects real code
4352 for anything but the stack pointer I don't know. */
4353 /* Make sure insns to set the frame pointer aren't deleted. */
4354 if (regno == FRAME_POINTER_REGNUM
4355 && (! reload_completed || frame_pointer_needed))
4357 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4358 if (regno == HARD_FRAME_POINTER_REGNUM
4359 && (! reload_completed || frame_pointer_needed))
4363 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4364 /* Make sure insns to set arg pointer are never deleted
4365 (if the arg pointer isn't fixed, there will be a USE
4366 for it, so we can treat it normally). */
4367 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
4371 /* Otherwise, the set is dead. */
4377 /* If performing several activities, insn is dead if each activity
4378 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4379 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4381 else if (code == PARALLEL)
4383 int i = XVECLEN (x, 0);
4385 for (i--; i >= 0; i--)
4386 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
4387 && GET_CODE (XVECEXP (x, 0, i)) != USE
4388 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
4394 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4395 is not necessarily true for hard registers. */
4396 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
4397 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
4398 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
4401 /* We do not check other CLOBBER or USE here. An insn consisting of just
4402 a CLOBBER or just a USE should not be deleted. */
4406 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4407 return 1 if the entire library call is dead.
4408 This is true if INSN copies a register (hard or pseudo)
4409 and if the hard return reg of the call insn is dead.
4410 (The caller should have tested the destination of the SET inside
4411 INSN already for death.)
4413 If this insn doesn't just copy a register, then we don't
4414 have an ordinary libcall. In that case, cse could not have
4415 managed to substitute the source for the dest later on,
4416 so we can assume the libcall is dead.
4418 PBI is the block info giving pseudoregs live before this insn.
4419 NOTE is the REG_RETVAL note of the insn. */
4422 libcall_dead_p (pbi, note, insn)
4423 struct propagate_block_info *pbi;
4427 rtx x = single_set (insn);
4431 register rtx r = SET_SRC (x);
4432 if (GET_CODE (r) == REG)
4434 rtx call = XEXP (note, 0);
4438 /* Find the call insn. */
4439 while (call != insn && GET_CODE (call) != CALL_INSN)
4440 call = NEXT_INSN (call);
4442 /* If there is none, do nothing special,
4443 since ordinary death handling can understand these insns. */
4447 /* See if the hard reg holding the value is dead.
4448 If this is a PARALLEL, find the call within it. */
4449 call_pat = PATTERN (call);
4450 if (GET_CODE (call_pat) == PARALLEL)
4452 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
4453 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
4454 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
4457 /* This may be a library call that is returning a value
4458 via invisible pointer. Do nothing special, since
4459 ordinary death handling can understand these insns. */
4463 call_pat = XVECEXP (call_pat, 0, i);
4466 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
4472 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4473 live at function entry. Don't count global register variables, variables
4474 in registers that can be used for function arg passing, or variables in
4475 fixed hard registers. */
4478 regno_uninitialized (regno)
4481 if (n_basic_blocks == 0
4482 || (regno < FIRST_PSEUDO_REGISTER
4483 && (global_regs[regno]
4484 || fixed_regs[regno]
4485 || FUNCTION_ARG_REGNO_P (regno))))
4488 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
4491 /* 1 if register REGNO was alive at a place where `setjmp' was called
4492 and was set more than once or is an argument.
4493 Such regs may be clobbered by `longjmp'. */
4496 regno_clobbered_at_setjmp (regno)
4499 if (n_basic_blocks == 0)
4502 return ((REG_N_SETS (regno) > 1
4503 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
4504 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
4507 /* INSN references memory, possibly using autoincrement addressing modes.
4508 Find any entries on the mem_set_list that need to be invalidated due
4509 to an address change. */
4512 invalidate_mems_from_autoinc (pbi, insn)
4513 struct propagate_block_info *pbi;
4516 rtx note = REG_NOTES (insn);
4517 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
4519 if (REG_NOTE_KIND (note) == REG_INC)
4521 rtx temp = pbi->mem_set_list;
4522 rtx prev = NULL_RTX;
4527 next = XEXP (temp, 1);
4528 if (reg_overlap_mentioned_p (XEXP (note, 0), XEXP (temp, 0)))
4530 /* Splice temp out of list. */
4532 XEXP (prev, 1) = next;
4534 pbi->mem_set_list = next;
4535 free_EXPR_LIST_node (temp);
4536 pbi->mem_set_list_len--;
4546 /* EXP is either a MEM or a REG. Remove any dependant entries
4547 from pbi->mem_set_list. */
4550 invalidate_mems_from_set (pbi, exp)
4551 struct propagate_block_info *pbi;
4554 rtx temp = pbi->mem_set_list;
4555 rtx prev = NULL_RTX;
4560 next = XEXP (temp, 1);
4561 if ((GET_CODE (exp) == MEM
4562 && output_dependence (XEXP (temp, 0), exp))
4563 || (GET_CODE (exp) == REG
4564 && reg_overlap_mentioned_p (exp, XEXP (temp, 0))))
4566 /* Splice this entry out of the list. */
4568 XEXP (prev, 1) = next;
4570 pbi->mem_set_list = next;
4571 free_EXPR_LIST_node (temp);
4572 pbi->mem_set_list_len--;
4580 /* Process the registers that are set within X. Their bits are set to
4581 1 in the regset DEAD, because they are dead prior to this insn.
4583 If INSN is nonzero, it is the insn being processed.
4585 FLAGS is the set of operations to perform. */
4588 mark_set_regs (pbi, x, insn)
4589 struct propagate_block_info *pbi;
4592 rtx cond = NULL_RTX;
4597 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
4599 if (REG_NOTE_KIND (link) == REG_INC)
4600 mark_set_1 (pbi, SET, XEXP (link, 0),
4601 (GET_CODE (x) == COND_EXEC
4602 ? COND_EXEC_TEST (x) : NULL_RTX),
4606 switch (code = GET_CODE (x))
4610 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
4614 cond = COND_EXEC_TEST (x);
4615 x = COND_EXEC_CODE (x);
4621 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
4623 rtx sub = XVECEXP (x, 0, i);
4624 switch (code = GET_CODE (sub))
4627 if (cond != NULL_RTX)
4630 cond = COND_EXEC_TEST (sub);
4631 sub = COND_EXEC_CODE (sub);
4632 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
4638 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
4653 /* Process a single SET rtx, X. */
4656 mark_set_1 (pbi, code, reg, cond, insn, flags)
4657 struct propagate_block_info *pbi;
4659 rtx reg, cond, insn;
4662 int regno_first = -1, regno_last = -1;
4666 /* Modifying just one hardware register of a multi-reg value or just a
4667 byte field of a register does not mean the value from before this insn
4668 is now dead. Of course, if it was dead after it's unused now. */
4670 switch (GET_CODE (reg))
4673 /* Some targets place small structures in registers for return values of
4674 functions. We have to detect this case specially here to get correct
4675 flow information. */
4676 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
4677 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
4678 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
4684 case STRICT_LOW_PART:
4685 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4687 reg = XEXP (reg, 0);
4688 while (GET_CODE (reg) == SUBREG
4689 || GET_CODE (reg) == ZERO_EXTRACT
4690 || GET_CODE (reg) == SIGN_EXTRACT
4691 || GET_CODE (reg) == STRICT_LOW_PART);
4692 if (GET_CODE (reg) == MEM)
4694 not_dead = REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
4698 regno_last = regno_first = REGNO (reg);
4699 if (regno_first < FIRST_PSEUDO_REGISTER)
4700 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
4704 if (GET_CODE (SUBREG_REG (reg)) == REG)
4706 enum machine_mode outer_mode = GET_MODE (reg);
4707 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
4709 /* Identify the range of registers affected. This is moderately
4710 tricky for hard registers. See alter_subreg. */
4712 regno_last = regno_first = REGNO (SUBREG_REG (reg));
4713 if (regno_first < FIRST_PSEUDO_REGISTER)
4715 #ifdef ALTER_HARD_SUBREG
4716 regno_first = ALTER_HARD_SUBREG (outer_mode, SUBREG_WORD (reg),
4717 inner_mode, regno_first);
4719 regno_first += SUBREG_WORD (reg);
4721 regno_last = (regno_first
4722 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
4724 /* Since we've just adjusted the register number ranges, make
4725 sure REG matches. Otherwise some_was_live will be clear
4726 when it shouldn't have been, and we'll create incorrect
4727 REG_UNUSED notes. */
4728 reg = gen_rtx_REG (outer_mode, regno_first);
4732 /* If the number of words in the subreg is less than the number
4733 of words in the full register, we have a well-defined partial
4734 set. Otherwise the high bits are undefined.
4736 This is only really applicable to pseudos, since we just took
4737 care of multi-word hard registers. */
4738 if (((GET_MODE_SIZE (outer_mode)
4739 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
4740 < ((GET_MODE_SIZE (inner_mode)
4741 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
4742 not_dead = REGNO_REG_SET_P (pbi->reg_live, regno_first);
4744 reg = SUBREG_REG (reg);
4748 reg = SUBREG_REG (reg);
4755 /* If this set is a MEM, then it kills any aliased writes.
4756 If this set is a REG, then it kills any MEMs which use the reg. */
4757 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
4759 if (GET_CODE (reg) == MEM || GET_CODE (reg) == REG)
4760 invalidate_mems_from_set (pbi, reg);
4762 /* If the memory reference had embedded side effects (autoincrement
4763 address modes. Then we may need to kill some entries on the
4765 if (insn && GET_CODE (reg) == MEM)
4766 invalidate_mems_from_autoinc (pbi, insn);
4768 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN
4769 && GET_CODE (reg) == MEM && ! side_effects_p (reg)
4770 /* ??? With more effort we could track conditional memory life. */
4772 /* We do not know the size of a BLKmode store, so we do not track
4773 them for redundant store elimination. */
4774 && GET_MODE (reg) != BLKmode
4775 /* There are no REG_INC notes for SP, so we can't assume we'll see
4776 everything that invalidates it. To be safe, don't eliminate any
4777 stores though SP; none of them should be redundant anyway. */
4778 && ! reg_mentioned_p (stack_pointer_rtx, reg))
4781 /* Store a copy of mem, otherwise the address may be
4782 scrogged by find_auto_inc. */
4783 if (flags & PROP_AUTOINC)
4784 reg = shallow_copy_rtx (reg);
4786 pbi->mem_set_list = alloc_EXPR_LIST (0, reg, pbi->mem_set_list);
4787 pbi->mem_set_list_len++;
4791 if (GET_CODE (reg) == REG
4792 && ! (regno_first == FRAME_POINTER_REGNUM
4793 && (! reload_completed || frame_pointer_needed))
4794 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4795 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
4796 && (! reload_completed || frame_pointer_needed))
4798 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4799 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
4803 int some_was_live = 0, some_was_dead = 0;
4805 for (i = regno_first; i <= regno_last; ++i)
4807 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
4810 /* Order of the set operation matters here since both
4811 sets may be the same. */
4812 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
4813 if (cond != NULL_RTX
4814 && ! REGNO_REG_SET_P (pbi->local_set, i))
4815 SET_REGNO_REG_SET (pbi->cond_local_set, i);
4817 SET_REGNO_REG_SET (pbi->local_set, i);
4819 if (code != CLOBBER)
4820 SET_REGNO_REG_SET (pbi->new_set, i);
4822 some_was_live |= needed_regno;
4823 some_was_dead |= ! needed_regno;
4826 #ifdef HAVE_conditional_execution
4827 /* Consider conditional death in deciding that the register needs
4829 if (some_was_live && ! not_dead
4830 /* The stack pointer is never dead. Well, not strictly true,
4831 but it's very difficult to tell from here. Hopefully
4832 combine_stack_adjustments will fix up the most egregious
4834 && regno_first != STACK_POINTER_REGNUM)
4836 for (i = regno_first; i <= regno_last; ++i)
4837 if (! mark_regno_cond_dead (pbi, i, cond))
4842 /* Additional data to record if this is the final pass. */
4843 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
4844 | PROP_DEATH_NOTES | PROP_AUTOINC))
4847 register int blocknum = pbi->bb->index;
4850 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4852 y = pbi->reg_next_use[regno_first];
4854 /* The next use is no longer next, since a store intervenes. */
4855 for (i = regno_first; i <= regno_last; ++i)
4856 pbi->reg_next_use[i] = 0;
4859 if (flags & PROP_REG_INFO)
4861 for (i = regno_first; i <= regno_last; ++i)
4863 /* Count (weighted) references, stores, etc. This counts a
4864 register twice if it is modified, but that is correct. */
4865 REG_N_SETS (i) += 1;
4866 REG_N_REFS (i) += (optimize_size ? 1
4867 : pbi->bb->loop_depth + 1);
4869 /* The insns where a reg is live are normally counted
4870 elsewhere, but we want the count to include the insn
4871 where the reg is set, and the normal counting mechanism
4872 would not count it. */
4873 REG_LIVE_LENGTH (i) += 1;
4876 /* If this is a hard reg, record this function uses the reg. */
4877 if (regno_first < FIRST_PSEUDO_REGISTER)
4879 for (i = regno_first; i <= regno_last; i++)
4880 regs_ever_live[i] = 1;
4884 /* Keep track of which basic blocks each reg appears in. */
4885 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
4886 REG_BASIC_BLOCK (regno_first) = blocknum;
4887 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
4888 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
4892 if (! some_was_dead)
4894 if (flags & PROP_LOG_LINKS)
4896 /* Make a logical link from the next following insn
4897 that uses this register, back to this insn.
4898 The following insns have already been processed.
4900 We don't build a LOG_LINK for hard registers containing
4901 in ASM_OPERANDs. If these registers get replaced,
4902 we might wind up changing the semantics of the insn,
4903 even if reload can make what appear to be valid
4904 assignments later. */
4905 if (y && (BLOCK_NUM (y) == blocknum)
4906 && (regno_first >= FIRST_PSEUDO_REGISTER
4907 || asm_noperands (PATTERN (y)) < 0))
4908 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
4913 else if (! some_was_live)
4915 if (flags & PROP_REG_INFO)
4916 REG_N_DEATHS (regno_first) += 1;
4918 if (flags & PROP_DEATH_NOTES)
4920 /* Note that dead stores have already been deleted
4921 when possible. If we get here, we have found a
4922 dead store that cannot be eliminated (because the
4923 same insn does something useful). Indicate this
4924 by marking the reg being set as dying here. */
4926 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4931 if (flags & PROP_DEATH_NOTES)
4933 /* This is a case where we have a multi-word hard register
4934 and some, but not all, of the words of the register are
4935 needed in subsequent insns. Write REG_UNUSED notes
4936 for those parts that were not needed. This case should
4939 for (i = regno_first; i <= regno_last; ++i)
4940 if (! REGNO_REG_SET_P (pbi->reg_live, i))
4942 = alloc_EXPR_LIST (REG_UNUSED,
4943 gen_rtx_REG (reg_raw_mode[i], i),
4949 /* Mark the register as being dead. */
4952 /* The stack pointer is never dead. Well, not strictly true,
4953 but it's very difficult to tell from here. Hopefully
4954 combine_stack_adjustments will fix up the most egregious
4956 && regno_first != STACK_POINTER_REGNUM)
4958 for (i = regno_first; i <= regno_last; ++i)
4959 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
4962 else if (GET_CODE (reg) == REG)
4964 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
4965 pbi->reg_next_use[regno_first] = 0;
4968 /* If this is the last pass and this is a SCRATCH, show it will be dying
4969 here and count it. */
4970 else if (GET_CODE (reg) == SCRATCH)
4972 if (flags & PROP_DEATH_NOTES)
4974 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
4978 #ifdef HAVE_conditional_execution
4979 /* Mark REGNO conditionally dead.
4980 Return true if the register is now unconditionally dead. */
4983 mark_regno_cond_dead (pbi, regno, cond)
4984 struct propagate_block_info *pbi;
4988 /* If this is a store to a predicate register, the value of the
4989 predicate is changing, we don't know that the predicate as seen
4990 before is the same as that seen after. Flush all dependent
4991 conditions from reg_cond_dead. This will make all such
4992 conditionally live registers unconditionally live. */
4993 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
4994 flush_reg_cond_reg (pbi, regno);
4996 /* If this is an unconditional store, remove any conditional
4997 life that may have existed. */
4998 if (cond == NULL_RTX)
4999 splay_tree_remove (pbi->reg_cond_dead, regno);
5002 splay_tree_node node;
5003 struct reg_cond_life_info *rcli;
5006 /* Otherwise this is a conditional set. Record that fact.
5007 It may have been conditionally used, or there may be a
5008 subsequent set with a complimentary condition. */
5010 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5013 /* The register was unconditionally live previously.
5014 Record the current condition as the condition under
5015 which it is dead. */
5016 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5017 rcli->condition = cond;
5018 splay_tree_insert (pbi->reg_cond_dead, regno,
5019 (splay_tree_value) rcli);
5021 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5023 /* Not unconditionaly dead. */
5028 /* The register was conditionally live previously.
5029 Add the new condition to the old. */
5030 rcli = (struct reg_cond_life_info *) node->value;
5031 ncond = rcli->condition;
5032 ncond = ior_reg_cond (ncond, cond, 1);
5034 /* If the register is now unconditionally dead,
5035 remove the entry in the splay_tree. */
5036 if (ncond == const1_rtx)
5037 splay_tree_remove (pbi->reg_cond_dead, regno);
5040 rcli->condition = ncond;
5042 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5044 /* Not unconditionaly dead. */
5053 /* Called from splay_tree_delete for pbi->reg_cond_life. */
5056 free_reg_cond_life_info (value)
5057 splay_tree_value value;
5059 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
5063 /* Helper function for flush_reg_cond_reg. */
5066 flush_reg_cond_reg_1 (node, data)
5067 splay_tree_node node;
5070 struct reg_cond_life_info *rcli;
5071 int *xdata = (int *) data;
5072 unsigned int regno = xdata[0];
5074 /* Don't need to search if last flushed value was farther on in
5075 the in-order traversal. */
5076 if (xdata[1] >= (int) node->key)
5079 /* Splice out portions of the expression that refer to regno. */
5080 rcli = (struct reg_cond_life_info *) node->value;
5081 rcli->condition = elim_reg_cond (rcli->condition, regno);
5083 /* If the entire condition is now false, signal the node to be removed. */
5084 if (rcli->condition == const0_rtx)
5086 xdata[1] = node->key;
5089 else if (rcli->condition == const1_rtx)
5095 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
5098 flush_reg_cond_reg (pbi, regno)
5099 struct propagate_block_info *pbi;
5106 while (splay_tree_foreach (pbi->reg_cond_dead,
5107 flush_reg_cond_reg_1, pair) == -1)
5108 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
5110 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
5113 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
5114 For ior/and, the ADD flag determines whether we want to add the new
5115 condition X to the old one unconditionally. If it is zero, we will
5116 only return a new expression if X allows us to simplify part of
5117 OLD, otherwise we return OLD unchanged to the caller.
5118 If ADD is nonzero, we will return a new condition in all cases. The
5119 toplevel caller of one of these functions should always pass 1 for
5123 ior_reg_cond (old, x, add)
5129 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5131 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5132 && GET_CODE (x) == reverse_condition (GET_CODE (old))
5133 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5135 if (GET_CODE (x) == GET_CODE (old)
5136 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5140 return gen_rtx_IOR (0, old, x);
5143 switch (GET_CODE (old))
5146 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5147 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5148 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5150 if (op0 == const0_rtx)
5152 if (op1 == const0_rtx)
5154 if (op0 == const1_rtx || op1 == const1_rtx)
5156 if (op0 == XEXP (old, 0))
5157 op0 = gen_rtx_IOR (0, op0, x);
5159 op1 = gen_rtx_IOR (0, op1, x);
5160 return gen_rtx_IOR (0, op0, op1);
5164 return gen_rtx_IOR (0, old, x);
5167 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
5168 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
5169 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5171 if (op0 == const1_rtx)
5173 if (op1 == const1_rtx)
5175 if (op0 == const0_rtx || op1 == const0_rtx)
5177 if (op0 == XEXP (old, 0))
5178 op0 = gen_rtx_IOR (0, op0, x);
5180 op1 = gen_rtx_IOR (0, op1, x);
5181 return gen_rtx_AND (0, op0, op1);
5185 return gen_rtx_IOR (0, old, x);
5188 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5189 if (op0 != XEXP (old, 0))
5190 return not_reg_cond (op0);
5193 return gen_rtx_IOR (0, old, x);
5204 enum rtx_code x_code;
5206 if (x == const0_rtx)
5208 else if (x == const1_rtx)
5210 x_code = GET_CODE (x);
5213 if (GET_RTX_CLASS (x_code) == '<'
5214 && GET_CODE (XEXP (x, 0)) == REG)
5216 if (XEXP (x, 1) != const0_rtx)
5219 return gen_rtx_fmt_ee (reverse_condition (x_code),
5220 VOIDmode, XEXP (x, 0), const0_rtx);
5222 return gen_rtx_NOT (0, x);
5226 and_reg_cond (old, x, add)
5232 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
5234 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
5235 && GET_CODE (x) == reverse_condition (GET_CODE (old))
5236 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5238 if (GET_CODE (x) == GET_CODE (old)
5239 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
5243 return gen_rtx_AND (0, old, x);
5246 switch (GET_CODE (old))
5249 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5250 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5251 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5253 if (op0 == const0_rtx)
5255 if (op1 == const0_rtx)
5257 if (op0 == const1_rtx || op1 == const1_rtx)
5259 if (op0 == XEXP (old, 0))
5260 op0 = gen_rtx_AND (0, op0, x);
5262 op1 = gen_rtx_AND (0, op1, x);
5263 return gen_rtx_IOR (0, op0, op1);
5267 return gen_rtx_AND (0, old, x);
5270 op0 = and_reg_cond (XEXP (old, 0), x, 0);
5271 op1 = and_reg_cond (XEXP (old, 1), x, 0);
5272 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
5274 if (op0 == const1_rtx)
5276 if (op1 == const1_rtx)
5278 if (op0 == const0_rtx || op1 == const0_rtx)
5280 if (op0 == XEXP (old, 0))
5281 op0 = gen_rtx_AND (0, op0, x);
5283 op1 = gen_rtx_AND (0, op1, x);
5284 return gen_rtx_AND (0, op0, op1);
5288 return gen_rtx_AND (0, old, x);
5291 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
5292 if (op0 != XEXP (old, 0))
5293 return not_reg_cond (op0);
5296 return gen_rtx_AND (0, old, x);
5303 /* Given a condition X, remove references to reg REGNO and return the
5304 new condition. The removal will be done so that all conditions
5305 involving REGNO are considered to evaluate to false. This function
5306 is used when the value of REGNO changes. */
5309 elim_reg_cond (x, regno)
5315 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
5317 if (REGNO (XEXP (x, 0)) == regno)
5322 switch (GET_CODE (x))
5325 op0 = elim_reg_cond (XEXP (x, 0), regno);
5326 op1 = elim_reg_cond (XEXP (x, 1), regno);
5327 if (op0 == const0_rtx || op1 == const0_rtx)
5329 if (op0 == const1_rtx)
5331 if (op1 == const1_rtx)
5333 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5335 return gen_rtx_AND (0, op0, op1);
5338 op0 = elim_reg_cond (XEXP (x, 0), regno);
5339 op1 = elim_reg_cond (XEXP (x, 1), regno);
5340 if (op0 == const1_rtx || op1 == const1_rtx)
5342 if (op0 == const0_rtx)
5344 if (op1 == const0_rtx)
5346 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
5348 return gen_rtx_IOR (0, op0, op1);
5351 op0 = elim_reg_cond (XEXP (x, 0), regno);
5352 if (op0 == const0_rtx)
5354 if (op0 == const1_rtx)
5356 if (op0 != XEXP (x, 0))
5357 return not_reg_cond (op0);
5364 #endif /* HAVE_conditional_execution */
5368 /* Try to substitute the auto-inc expression INC as the address inside
5369 MEM which occurs in INSN. Currently, the address of MEM is an expression
5370 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
5371 that has a single set whose source is a PLUS of INCR_REG and something
5375 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
5376 struct propagate_block_info *pbi;
5377 rtx inc, insn, mem, incr, incr_reg;
5379 int regno = REGNO (incr_reg);
5380 rtx set = single_set (incr);
5381 rtx q = SET_DEST (set);
5382 rtx y = SET_SRC (set);
5383 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
5385 /* Make sure this reg appears only once in this insn. */
5386 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
5389 if (dead_or_set_p (incr, incr_reg)
5390 /* Mustn't autoinc an eliminable register. */
5391 && (regno >= FIRST_PSEUDO_REGISTER
5392 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
5394 /* This is the simple case. Try to make the auto-inc. If
5395 we can't, we are done. Otherwise, we will do any
5396 needed updates below. */
5397 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
5400 else if (GET_CODE (q) == REG
5401 /* PREV_INSN used here to check the semi-open interval
5403 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
5404 /* We must also check for sets of q as q may be
5405 a call clobbered hard register and there may
5406 be a call between PREV_INSN (insn) and incr. */
5407 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
5409 /* We have *p followed sometime later by q = p+size.
5410 Both p and q must be live afterward,
5411 and q is not used between INSN and its assignment.
5412 Change it to q = p, ...*q..., q = q+size.
5413 Then fall into the usual case. */
5417 emit_move_insn (q, incr_reg);
5418 insns = get_insns ();
5421 if (basic_block_for_insn)
5422 for (temp = insns; temp; temp = NEXT_INSN (temp))
5423 set_block_for_insn (temp, pbi->bb);
5425 /* If we can't make the auto-inc, or can't make the
5426 replacement into Y, exit. There's no point in making
5427 the change below if we can't do the auto-inc and doing
5428 so is not correct in the pre-inc case. */
5431 validate_change (insn, &XEXP (mem, 0), inc, 1);
5432 validate_change (incr, &XEXP (y, opnum), q, 1);
5433 if (! apply_change_group ())
5436 /* We now know we'll be doing this change, so emit the
5437 new insn(s) and do the updates. */
5438 emit_insns_before (insns, insn);
5440 if (pbi->bb->head == insn)
5441 pbi->bb->head = insns;
5443 /* INCR will become a NOTE and INSN won't contain a
5444 use of INCR_REG. If a use of INCR_REG was just placed in
5445 the insn before INSN, make that the next use.
5446 Otherwise, invalidate it. */
5447 if (GET_CODE (PREV_INSN (insn)) == INSN
5448 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
5449 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
5450 pbi->reg_next_use[regno] = PREV_INSN (insn);
5452 pbi->reg_next_use[regno] = 0;
5457 /* REGNO is now used in INCR which is below INSN, but
5458 it previously wasn't live here. If we don't mark
5459 it as live, we'll put a REG_DEAD note for it
5460 on this insn, which is incorrect. */
5461 SET_REGNO_REG_SET (pbi->reg_live, regno);
5463 /* If there are any calls between INSN and INCR, show
5464 that REGNO now crosses them. */
5465 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
5466 if (GET_CODE (temp) == CALL_INSN)
5467 REG_N_CALLS_CROSSED (regno)++;
5472 /* If we haven't returned, it means we were able to make the
5473 auto-inc, so update the status. First, record that this insn
5474 has an implicit side effect. */
5476 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
5478 /* Modify the old increment-insn to simply copy
5479 the already-incremented value of our register. */
5480 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
5483 /* If that makes it a no-op (copying the register into itself) delete
5484 it so it won't appear to be a "use" and a "set" of this
5486 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
5488 /* If the original source was dead, it's dead now. */
5491 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
5493 remove_note (incr, note);
5494 if (XEXP (note, 0) != incr_reg)
5495 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
5498 PUT_CODE (incr, NOTE);
5499 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
5500 NOTE_SOURCE_FILE (incr) = 0;
5503 if (regno >= FIRST_PSEUDO_REGISTER)
5505 /* Count an extra reference to the reg. When a reg is
5506 incremented, spilling it is worse, so we want to make
5507 that less likely. */
5508 REG_N_REFS (regno) += (optimize_size ? 1 : pbi->bb->loop_depth + 1);
5510 /* Count the increment as a setting of the register,
5511 even though it isn't a SET in rtl. */
5512 REG_N_SETS (regno)++;
5516 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
5520 find_auto_inc (pbi, x, insn)
5521 struct propagate_block_info *pbi;
5525 rtx addr = XEXP (x, 0);
5526 HOST_WIDE_INT offset = 0;
5527 rtx set, y, incr, inc_val;
5529 int size = GET_MODE_SIZE (GET_MODE (x));
5531 if (GET_CODE (insn) == JUMP_INSN)
5534 /* Here we detect use of an index register which might be good for
5535 postincrement, postdecrement, preincrement, or predecrement. */
5537 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
5538 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
5540 if (GET_CODE (addr) != REG)
5543 regno = REGNO (addr);
5545 /* Is the next use an increment that might make auto-increment? */
5546 incr = pbi->reg_next_use[regno];
5547 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
5549 set = single_set (incr);
5550 if (set == 0 || GET_CODE (set) != SET)
5554 if (GET_CODE (y) != PLUS)
5557 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
5558 inc_val = XEXP (y, 1);
5559 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
5560 inc_val = XEXP (y, 0);
5564 if (GET_CODE (inc_val) == CONST_INT)
5566 if (HAVE_POST_INCREMENT
5567 && (INTVAL (inc_val) == size && offset == 0))
5568 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
5570 else if (HAVE_POST_DECREMENT
5571 && (INTVAL (inc_val) == -size && offset == 0))
5572 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
5574 else if (HAVE_PRE_INCREMENT
5575 && (INTVAL (inc_val) == size && offset == size))
5576 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
5578 else if (HAVE_PRE_DECREMENT
5579 && (INTVAL (inc_val) == -size && offset == -size))
5580 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
5582 else if (HAVE_POST_MODIFY_DISP && offset == 0)
5583 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5584 gen_rtx_PLUS (Pmode,
5587 insn, x, incr, addr);
5589 else if (GET_CODE (inc_val) == REG
5590 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
5594 if (HAVE_POST_MODIFY_REG && offset == 0)
5595 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
5596 gen_rtx_PLUS (Pmode,
5599 insn, x, incr, addr);
5603 #endif /* AUTO_INC_DEC */
5606 mark_used_reg (pbi, reg, cond, insn)
5607 struct propagate_block_info *pbi;
5609 rtx cond ATTRIBUTE_UNUSED;
5612 int regno = REGNO (reg);
5613 int some_was_live = REGNO_REG_SET_P (pbi->reg_live, regno);
5614 int some_was_dead = ! some_was_live;
5618 /* A hard reg in a wide mode may really be multiple registers.
5619 If so, mark all of them just like the first. */
5620 if (regno < FIRST_PSEUDO_REGISTER)
5622 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5625 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, regno + n);
5626 some_was_live |= needed_regno;
5627 some_was_dead |= ! needed_regno;
5631 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
5633 /* Record where each reg is used, so when the reg is set we know
5634 the next insn that uses it. */
5635 pbi->reg_next_use[regno] = insn;
5638 if (pbi->flags & PROP_REG_INFO)
5640 if (regno < FIRST_PSEUDO_REGISTER)
5642 /* If this is a register we are going to try to eliminate,
5643 don't mark it live here. If we are successful in
5644 eliminating it, it need not be live unless it is used for
5645 pseudos, in which case it will have been set live when it
5646 was allocated to the pseudos. If the register will not
5647 be eliminated, reload will set it live at that point.
5649 Otherwise, record that this function uses this register. */
5650 /* ??? The PPC backend tries to "eliminate" on the pic
5651 register to itself. This should be fixed. In the mean
5652 time, hack around it. */
5654 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno)
5655 && (regno == FRAME_POINTER_REGNUM
5656 || regno == ARG_POINTER_REGNUM)))
5658 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5660 regs_ever_live[regno + --n] = 1;
5666 /* Keep track of which basic block each reg appears in. */
5668 register int blocknum = pbi->bb->index;
5669 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
5670 REG_BASIC_BLOCK (regno) = blocknum;
5671 else if (REG_BASIC_BLOCK (regno) != blocknum)
5672 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
5674 /* Count (weighted) number of uses of each reg. */
5675 REG_N_REFS (regno) += (optimize_size ? 1
5676 : pbi->bb->loop_depth + 1);
5680 /* Find out if any of the register was set this insn. */
5681 some_not_set = ! REGNO_REG_SET_P (pbi->new_set, regno);
5682 if (regno < FIRST_PSEUDO_REGISTER)
5684 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5686 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, regno + n);
5689 /* Record and count the insns in which a reg dies. If it is used in
5690 this insn and was dead below the insn then it dies in this insn.
5691 If it was set in this insn, we do not make a REG_DEAD note;
5692 likewise if we already made such a note. */
5693 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
5697 /* Check for the case where the register dying partially
5698 overlaps the register set by this insn. */
5699 if (regno < FIRST_PSEUDO_REGISTER
5700 && HARD_REGNO_NREGS (regno, GET_MODE (reg)) > 1)
5702 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5704 some_was_live |= REGNO_REG_SET_P (pbi->new_set, regno + n);
5707 /* If none of the words in X is needed, make a REG_DEAD note.
5708 Otherwise, we must make partial REG_DEAD notes. */
5709 if (! some_was_live)
5711 if ((pbi->flags & PROP_DEATH_NOTES)
5712 && ! find_regno_note (insn, REG_DEAD, regno))
5714 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
5716 if (pbi->flags & PROP_REG_INFO)
5717 REG_N_DEATHS (regno)++;
5721 /* Don't make a REG_DEAD note for a part of a register
5722 that is set in the insn. */
5724 n = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
5725 for (; n >= regno; n--)
5726 if (! REGNO_REG_SET_P (pbi->reg_live, n)
5727 && ! dead_or_set_regno_p (insn, n))
5729 = alloc_EXPR_LIST (REG_DEAD,
5730 gen_rtx_REG (reg_raw_mode[n], n),
5735 SET_REGNO_REG_SET (pbi->reg_live, regno);
5736 if (regno < FIRST_PSEUDO_REGISTER)
5738 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
5740 SET_REGNO_REG_SET (pbi->reg_live, regno + n);
5743 #ifdef HAVE_conditional_execution
5744 /* If this is a conditional use, record that fact. If it is later
5745 conditionally set, we'll know to kill the register. */
5746 if (cond != NULL_RTX)
5748 splay_tree_node node;
5749 struct reg_cond_life_info *rcli;
5754 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5757 /* The register was unconditionally live previously.
5758 No need to do anything. */
5762 /* The register was conditionally live previously.
5763 Subtract the new life cond from the old death cond. */
5764 rcli = (struct reg_cond_life_info *) node->value;
5765 ncond = rcli->condition;
5766 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
5768 /* If the register is now unconditionally live, remove the
5769 entry in the splay_tree. */
5770 if (ncond == const0_rtx)
5772 rcli->condition = NULL_RTX;
5773 splay_tree_remove (pbi->reg_cond_dead, regno);
5777 rcli->condition = ncond;
5778 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5784 /* The register was not previously live at all. Record
5785 the condition under which it is still dead. */
5786 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
5787 rcli->condition = not_reg_cond (cond);
5788 splay_tree_insert (pbi->reg_cond_dead, regno,
5789 (splay_tree_value) rcli);
5791 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
5794 else if (some_was_live)
5796 splay_tree_node node;
5797 struct reg_cond_life_info *rcli;
5799 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
5802 /* The register was conditionally live previously, but is now
5803 unconditionally so. Remove it from the conditionally dead
5804 list, so that a conditional set won't cause us to think
5806 rcli = (struct reg_cond_life_info *) node->value;
5807 rcli->condition = NULL_RTX;
5808 splay_tree_remove (pbi->reg_cond_dead, regno);
5815 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5816 This is done assuming the registers needed from X are those that
5817 have 1-bits in PBI->REG_LIVE.
5819 INSN is the containing instruction. If INSN is dead, this function
5823 mark_used_regs (pbi, x, cond, insn)
5824 struct propagate_block_info *pbi;
5827 register RTX_CODE code;
5829 int flags = pbi->flags;
5832 code = GET_CODE (x);
5852 /* If we are clobbering a MEM, mark any registers inside the address
5854 if (GET_CODE (XEXP (x, 0)) == MEM)
5855 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
5859 /* Don't bother watching stores to mems if this is not the
5860 final pass. We'll not be deleting dead stores this round. */
5861 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
5863 /* Invalidate the data for the last MEM stored, but only if MEM is
5864 something that can be stored into. */
5865 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
5866 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
5867 /* Needn't clear the memory set list. */
5871 rtx temp = pbi->mem_set_list;
5872 rtx prev = NULL_RTX;
5877 next = XEXP (temp, 1);
5878 if (anti_dependence (XEXP (temp, 0), x))
5880 /* Splice temp out of the list. */
5882 XEXP (prev, 1) = next;
5884 pbi->mem_set_list = next;
5885 free_EXPR_LIST_node (temp);
5886 pbi->mem_set_list_len--;
5894 /* If the memory reference had embedded side effects (autoincrement
5895 address modes. Then we may need to kill some entries on the
5898 invalidate_mems_from_autoinc (pbi, insn);
5902 if (flags & PROP_AUTOINC)
5903 find_auto_inc (pbi, x, insn);
5908 #ifdef CLASS_CANNOT_CHANGE_MODE
5909 if (GET_CODE (SUBREG_REG (x)) == REG
5910 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
5911 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
5912 GET_MODE (SUBREG_REG (x))))
5913 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
5916 /* While we're here, optimize this case. */
5918 if (GET_CODE (x) != REG)
5923 /* See a register other than being set => mark it as needed. */
5924 mark_used_reg (pbi, x, cond, insn);
5929 register rtx testreg = SET_DEST (x);
5932 /* If storing into MEM, don't show it as being used. But do
5933 show the address as being used. */
5934 if (GET_CODE (testreg) == MEM)
5937 if (flags & PROP_AUTOINC)
5938 find_auto_inc (pbi, testreg, insn);
5940 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
5941 mark_used_regs (pbi, SET_SRC (x), cond, insn);
5945 /* Storing in STRICT_LOW_PART is like storing in a reg
5946 in that this SET might be dead, so ignore it in TESTREG.
5947 but in some other ways it is like using the reg.
5949 Storing in a SUBREG or a bit field is like storing the entire
5950 register in that if the register's value is not used
5951 then this SET is not needed. */
5952 while (GET_CODE (testreg) == STRICT_LOW_PART
5953 || GET_CODE (testreg) == ZERO_EXTRACT
5954 || GET_CODE (testreg) == SIGN_EXTRACT
5955 || GET_CODE (testreg) == SUBREG)
5957 #ifdef CLASS_CANNOT_CHANGE_MODE
5958 if (GET_CODE (testreg) == SUBREG
5959 && GET_CODE (SUBREG_REG (testreg)) == REG
5960 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
5961 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
5962 GET_MODE (testreg)))
5963 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
5966 /* Modifying a single register in an alternate mode
5967 does not use any of the old value. But these other
5968 ways of storing in a register do use the old value. */
5969 if (GET_CODE (testreg) == SUBREG
5970 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
5975 testreg = XEXP (testreg, 0);
5978 /* If this is a store into a register or group of registers,
5979 recursively scan the value being stored. */
5981 if ((GET_CODE (testreg) == PARALLEL
5982 && GET_MODE (testreg) == BLKmode)
5983 || (GET_CODE (testreg) == REG
5984 && (regno = REGNO (testreg),
5985 ! (regno == FRAME_POINTER_REGNUM
5986 && (! reload_completed || frame_pointer_needed)))
5987 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5988 && ! (regno == HARD_FRAME_POINTER_REGNUM
5989 && (! reload_completed || frame_pointer_needed))
5991 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5992 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
5997 mark_used_regs (pbi, SET_DEST (x), cond, insn);
5998 mark_used_regs (pbi, SET_SRC (x), cond, insn);
6005 case UNSPEC_VOLATILE:
6009 /* Traditional and volatile asm instructions must be considered to use
6010 and clobber all hard registers, all pseudo-registers and all of
6011 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
6013 Consider for instance a volatile asm that changes the fpu rounding
6014 mode. An insn should not be moved across this even if it only uses
6015 pseudo-regs because it might give an incorrectly rounded result.
6017 ?!? Unfortunately, marking all hard registers as live causes massive
6018 problems for the register allocator and marking all pseudos as live
6019 creates mountains of uninitialized variable warnings.
6021 So for now, just clear the memory set list and mark any regs
6022 we can find in ASM_OPERANDS as used. */
6023 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
6025 free_EXPR_LIST_list (&pbi->mem_set_list);
6026 pbi->mem_set_list_len = 0;
6029 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
6030 We can not just fall through here since then we would be confused
6031 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
6032 traditional asms unlike their normal usage. */
6033 if (code == ASM_OPERANDS)
6037 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
6038 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
6044 if (cond != NULL_RTX)
6047 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
6049 cond = COND_EXEC_TEST (x);
6050 x = COND_EXEC_CODE (x);
6054 /* We _do_not_ want to scan operands of phi nodes. Operands of
6055 a phi function are evaluated only when control reaches this
6056 block along a particular edge. Therefore, regs that appear
6057 as arguments to phi should not be added to the global live at
6065 /* Recursively scan the operands of this expression. */
6068 register const char *fmt = GET_RTX_FORMAT (code);
6071 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6075 /* Tail recursive case: save a function call level. */
6081 mark_used_regs (pbi, XEXP (x, i), cond, insn);
6083 else if (fmt[i] == 'E')
6086 for (j = 0; j < XVECLEN (x, i); j++)
6087 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
6096 try_pre_increment_1 (pbi, insn)
6097 struct propagate_block_info *pbi;
6100 /* Find the next use of this reg. If in same basic block,
6101 make it do pre-increment or pre-decrement if appropriate. */
6102 rtx x = single_set (insn);
6103 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
6104 * INTVAL (XEXP (SET_SRC (x), 1)));
6105 int regno = REGNO (SET_DEST (x));
6106 rtx y = pbi->reg_next_use[regno];
6108 && SET_DEST (x) != stack_pointer_rtx
6109 && BLOCK_NUM (y) == BLOCK_NUM (insn)
6110 /* Don't do this if the reg dies, or gets set in y; a standard addressing
6111 mode would be better. */
6112 && ! dead_or_set_p (y, SET_DEST (x))
6113 && try_pre_increment (y, SET_DEST (x), amount))
6115 /* We have found a suitable auto-increment and already changed
6116 insn Y to do it. So flush this increment instruction. */
6117 propagate_block_delete_insn (pbi->bb, insn);
6119 /* Count a reference to this reg for the increment insn we are
6120 deleting. When a reg is incremented, spilling it is worse,
6121 so we want to make that less likely. */
6122 if (regno >= FIRST_PSEUDO_REGISTER)
6124 REG_N_REFS (regno) += (optimize_size ? 1
6125 : pbi->bb->loop_depth + 1);
6126 REG_N_SETS (regno)++;
6129 /* Flush any remembered memories depending on the value of
6130 the incremented register. */
6131 invalidate_mems_from_set (pbi, SET_DEST (x));
6138 /* Try to change INSN so that it does pre-increment or pre-decrement
6139 addressing on register REG in order to add AMOUNT to REG.
6140 AMOUNT is negative for pre-decrement.
6141 Returns 1 if the change could be made.
6142 This checks all about the validity of the result of modifying INSN. */
6145 try_pre_increment (insn, reg, amount)
6147 HOST_WIDE_INT amount;
6151 /* Nonzero if we can try to make a pre-increment or pre-decrement.
6152 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
6154 /* Nonzero if we can try to make a post-increment or post-decrement.
6155 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
6156 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
6157 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
6160 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
6163 /* From the sign of increment, see which possibilities are conceivable
6164 on this target machine. */
6165 if (HAVE_PRE_INCREMENT && amount > 0)
6167 if (HAVE_POST_INCREMENT && amount > 0)
6170 if (HAVE_PRE_DECREMENT && amount < 0)
6172 if (HAVE_POST_DECREMENT && amount < 0)
6175 if (! (pre_ok || post_ok))
6178 /* It is not safe to add a side effect to a jump insn
6179 because if the incremented register is spilled and must be reloaded
6180 there would be no way to store the incremented value back in memory. */
6182 if (GET_CODE (insn) == JUMP_INSN)
6187 use = find_use_as_address (PATTERN (insn), reg, 0);
6188 if (post_ok && (use == 0 || use == (rtx) 1))
6190 use = find_use_as_address (PATTERN (insn), reg, -amount);
6194 if (use == 0 || use == (rtx) 1)
6197 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
6200 /* See if this combination of instruction and addressing mode exists. */
6201 if (! validate_change (insn, &XEXP (use, 0),
6202 gen_rtx_fmt_e (amount > 0
6203 ? (do_post ? POST_INC : PRE_INC)
6204 : (do_post ? POST_DEC : PRE_DEC),
6208 /* Record that this insn now has an implicit side effect on X. */
6209 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
6213 #endif /* AUTO_INC_DEC */
6215 /* Find the place in the rtx X where REG is used as a memory address.
6216 Return the MEM rtx that so uses it.
6217 If PLUSCONST is nonzero, search instead for a memory address equivalent to
6218 (plus REG (const_int PLUSCONST)).
6220 If such an address does not appear, return 0.
6221 If REG appears more than once, or is used other than in such an address,
6225 find_use_as_address (x, reg, plusconst)
6228 HOST_WIDE_INT plusconst;
6230 enum rtx_code code = GET_CODE (x);
6231 const char *fmt = GET_RTX_FORMAT (code);
6233 register rtx value = 0;
6236 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
6239 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
6240 && XEXP (XEXP (x, 0), 0) == reg
6241 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
6242 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
6245 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
6247 /* If REG occurs inside a MEM used in a bit-field reference,
6248 that is unacceptable. */
6249 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
6250 return (rtx) (HOST_WIDE_INT) 1;
6254 return (rtx) (HOST_WIDE_INT) 1;
6256 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
6260 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
6264 return (rtx) (HOST_WIDE_INT) 1;
6266 else if (fmt[i] == 'E')
6269 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6271 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
6275 return (rtx) (HOST_WIDE_INT) 1;
6283 /* Write information about registers and basic blocks into FILE.
6284 This is part of making a debugging dump. */
6287 dump_regset (r, outf)
6294 fputs (" (nil)", outf);
6298 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
6300 fprintf (outf, " %d", i);
6301 if (i < FIRST_PSEUDO_REGISTER)
6302 fprintf (outf, " [%s]",
6311 dump_regset (r, stderr);
6312 putc ('\n', stderr);
6316 dump_flow_info (file)
6320 static const char * const reg_class_names[] = REG_CLASS_NAMES;
6322 fprintf (file, "%d registers.\n", max_regno);
6323 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
6326 enum reg_class class, altclass;
6327 fprintf (file, "\nRegister %d used %d times across %d insns",
6328 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
6329 if (REG_BASIC_BLOCK (i) >= 0)
6330 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
6332 fprintf (file, "; set %d time%s", REG_N_SETS (i),
6333 (REG_N_SETS (i) == 1) ? "" : "s");
6334 if (REG_USERVAR_P (regno_reg_rtx[i]))
6335 fprintf (file, "; user var");
6336 if (REG_N_DEATHS (i) != 1)
6337 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
6338 if (REG_N_CALLS_CROSSED (i) == 1)
6339 fprintf (file, "; crosses 1 call");
6340 else if (REG_N_CALLS_CROSSED (i))
6341 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
6342 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
6343 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
6344 class = reg_preferred_class (i);
6345 altclass = reg_alternate_class (i);
6346 if (class != GENERAL_REGS || altclass != ALL_REGS)
6348 if (altclass == ALL_REGS || class == ALL_REGS)
6349 fprintf (file, "; pref %s", reg_class_names[(int) class]);
6350 else if (altclass == NO_REGS)
6351 fprintf (file, "; %s or none", reg_class_names[(int) class]);
6353 fprintf (file, "; pref %s, else %s",
6354 reg_class_names[(int) class],
6355 reg_class_names[(int) altclass]);
6357 if (REG_POINTER (regno_reg_rtx[i]))
6358 fprintf (file, "; pointer");
6359 fprintf (file, ".\n");
6362 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
6363 for (i = 0; i < n_basic_blocks; i++)
6365 register basic_block bb = BASIC_BLOCK (i);
6368 fprintf (file, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
6369 i, INSN_UID (bb->head), INSN_UID (bb->end), bb->loop_depth, bb->count);
6371 fprintf (file, "Predecessors: ");
6372 for (e = bb->pred; e; e = e->pred_next)
6373 dump_edge_info (file, e, 0);
6375 fprintf (file, "\nSuccessors: ");
6376 for (e = bb->succ; e; e = e->succ_next)
6377 dump_edge_info (file, e, 1);
6379 fprintf (file, "\nRegisters live at start:");
6380 dump_regset (bb->global_live_at_start, file);
6382 fprintf (file, "\nRegisters live at end:");
6383 dump_regset (bb->global_live_at_end, file);
6394 dump_flow_info (stderr);
6398 dump_edge_info (file, e, do_succ)
6403 basic_block side = (do_succ ? e->dest : e->src);
6405 if (side == ENTRY_BLOCK_PTR)
6406 fputs (" ENTRY", file);
6407 else if (side == EXIT_BLOCK_PTR)
6408 fputs (" EXIT", file);
6410 fprintf (file, " %d", side->index);
6413 fprintf (file, " count:%d", e->count);
6417 static const char * const bitnames[] = {
6418 "fallthru", "crit", "ab", "abcall", "eh", "fake"
6421 int i, flags = e->flags;
6425 for (i = 0; flags; i++)
6426 if (flags & (1 << i))
6432 if (i < (int) ARRAY_SIZE (bitnames))
6433 fputs (bitnames[i], file);
6435 fprintf (file, "%d", i);
6442 /* Print out one basic block with live information at start and end. */
6453 fprintf (outf, ";; Basic block %d, loop depth %d, count %d",
6454 bb->index, bb->loop_depth, bb->count);
6455 if (bb->eh_beg != -1 || bb->eh_end != -1)
6456 fprintf (outf, ", eh regions %d/%d", bb->eh_beg, bb->eh_end);
6459 fputs (";; Predecessors: ", outf);
6460 for (e = bb->pred; e; e = e->pred_next)
6461 dump_edge_info (outf, e, 0);
6464 fputs (";; Registers live at start:", outf);
6465 dump_regset (bb->global_live_at_start, outf);
6468 for (insn = bb->head, last = NEXT_INSN (bb->end);
6470 insn = NEXT_INSN (insn))
6471 print_rtl_single (outf, insn);
6473 fputs (";; Registers live at end:", outf);
6474 dump_regset (bb->global_live_at_end, outf);
6477 fputs (";; Successors: ", outf);
6478 for (e = bb->succ; e; e = e->succ_next)
6479 dump_edge_info (outf, e, 1);
6487 dump_bb (bb, stderr);
6494 dump_bb (BASIC_BLOCK (n), stderr);
6497 /* Like print_rtl, but also print out live information for the start of each
6501 print_rtl_with_bb (outf, rtx_first)
6505 register rtx tmp_rtx;
6508 fprintf (outf, "(nil)\n");
6512 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
6513 int max_uid = get_max_uid ();
6514 basic_block *start = (basic_block *)
6515 xcalloc (max_uid, sizeof (basic_block));
6516 basic_block *end = (basic_block *)
6517 xcalloc (max_uid, sizeof (basic_block));
6518 enum bb_state *in_bb_p = (enum bb_state *)
6519 xcalloc (max_uid, sizeof (enum bb_state));
6521 for (i = n_basic_blocks - 1; i >= 0; i--)
6523 basic_block bb = BASIC_BLOCK (i);
6526 start[INSN_UID (bb->head)] = bb;
6527 end[INSN_UID (bb->end)] = bb;
6528 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
6530 enum bb_state state = IN_MULTIPLE_BB;
6531 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
6533 in_bb_p[INSN_UID (x)] = state;
6540 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
6545 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
6547 fprintf (outf, ";; Start of basic block %d, registers live:",
6549 dump_regset (bb->global_live_at_start, outf);
6553 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
6554 && GET_CODE (tmp_rtx) != NOTE
6555 && GET_CODE (tmp_rtx) != BARRIER)
6556 fprintf (outf, ";; Insn is not within a basic block\n");
6557 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
6558 fprintf (outf, ";; Insn is in multiple basic blocks\n");
6560 did_output = print_rtl_single (outf, tmp_rtx);
6562 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
6564 fprintf (outf, ";; End of basic block %d, registers live:\n",
6566 dump_regset (bb->global_live_at_end, outf);
6579 if (current_function_epilogue_delay_list != 0)
6581 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
6582 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
6583 tmp_rtx = XEXP (tmp_rtx, 1))
6584 print_rtl_single (outf, XEXP (tmp_rtx, 0));
6588 /* Dump the rtl into the current debugging dump file, then abort. */
6590 print_rtl_and_abort ()
6594 print_rtl_with_bb (rtl_dump_file, get_insns ());
6595 fclose (rtl_dump_file);
6600 /* Recompute register set/reference counts immediately prior to register
6603 This avoids problems with set/reference counts changing to/from values
6604 which have special meanings to the register allocators.
6606 Additionally, the reference counts are the primary component used by the
6607 register allocators to prioritize pseudos for allocation to hard regs.
6608 More accurate reference counts generally lead to better register allocation.
6610 F is the first insn to be scanned.
6612 LOOP_STEP denotes how much loop_depth should be incremented per
6613 loop nesting level in order to increase the ref count more for
6614 references in a loop.
6616 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6617 possibly other information which is used by the register allocators. */
6620 recompute_reg_usage (f, loop_step)
6621 rtx f ATTRIBUTE_UNUSED;
6622 int loop_step ATTRIBUTE_UNUSED;
6624 allocate_reg_life_data ();
6625 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
6628 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6629 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6630 of the number of registers that died. */
6633 count_or_remove_death_notes (blocks, kill)
6639 for (i = n_basic_blocks - 1; i >= 0; --i)
6644 if (blocks && ! TEST_BIT (blocks, i))
6647 bb = BASIC_BLOCK (i);
6649 for (insn = bb->head;; insn = NEXT_INSN (insn))
6653 rtx *pprev = ®_NOTES (insn);
6658 switch (REG_NOTE_KIND (link))
6661 if (GET_CODE (XEXP (link, 0)) == REG)
6663 rtx reg = XEXP (link, 0);
6666 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
6669 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
6677 rtx next = XEXP (link, 1);
6678 free_EXPR_LIST_node (link);
6679 *pprev = link = next;
6685 pprev = &XEXP (link, 1);
6692 if (insn == bb->end)
6701 /* Update insns block within BB. */
6704 update_bb_for_insn (bb)
6709 if (! basic_block_for_insn)
6712 for (insn = bb->head; ; insn = NEXT_INSN (insn))
6714 set_block_for_insn (insn, bb);
6716 if (insn == bb->end)
6722 /* Record INSN's block as BB. */
6725 set_block_for_insn (insn, bb)
6729 size_t uid = INSN_UID (insn);
6730 if (uid >= basic_block_for_insn->num_elements)
6734 /* Add one-eighth the size so we don't keep calling xrealloc. */
6735 new_size = uid + (uid + 7) / 8;
6737 VARRAY_GROW (basic_block_for_insn, new_size);
6739 VARRAY_BB (basic_block_for_insn, uid) = bb;
6742 /* Record INSN's block number as BB. */
6743 /* ??? This has got to go. */
6746 set_block_num (insn, bb)
6750 set_block_for_insn (insn, BASIC_BLOCK (bb));
6753 /* Verify the CFG consistency. This function check some CFG invariants and
6754 aborts when something is wrong. Hope that this function will help to
6755 convert many optimization passes to preserve CFG consistent.
6757 Currently it does following checks:
6759 - test head/end pointers
6760 - overlapping of basic blocks
6761 - edge list corectness
6762 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6763 - tails of basic blocks (ensure that boundary is necesary)
6764 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6765 and NOTE_INSN_BASIC_BLOCK
6766 - check that all insns are in the basic blocks
6767 (except the switch handling code, barriers and notes)
6768 - check that all returns are followed by barriers
6770 In future it can be extended check a lot of other stuff as well
6771 (reachability of basic blocks, life information, etc. etc.). */
6776 const int max_uid = get_max_uid ();
6777 const rtx rtx_first = get_insns ();
6778 rtx last_head = get_last_insn ();
6779 basic_block *bb_info;
6781 int i, last_bb_num_seen, num_bb_notes, err = 0;
6783 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
6785 for (i = n_basic_blocks - 1; i >= 0; i--)
6787 basic_block bb = BASIC_BLOCK (i);
6788 rtx head = bb->head;
6791 /* Verify the end of the basic block is in the INSN chain. */
6792 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
6797 error ("End insn %d for block %d not found in the insn stream.",
6798 INSN_UID (end), bb->index);
6802 /* Work backwards from the end to the head of the basic block
6803 to verify the head is in the RTL chain. */
6804 for (; x != NULL_RTX; x = PREV_INSN (x))
6806 /* While walking over the insn chain, verify insns appear
6807 in only one basic block and initialize the BB_INFO array
6808 used by other passes. */
6809 if (bb_info[INSN_UID (x)] != NULL)
6811 error ("Insn %d is in multiple basic blocks (%d and %d)",
6812 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
6815 bb_info[INSN_UID (x)] = bb;
6822 error ("Head insn %d for block %d not found in the insn stream.",
6823 INSN_UID (head), bb->index);
6830 /* Now check the basic blocks (boundaries etc.) */
6831 for (i = n_basic_blocks - 1; i >= 0; i--)
6833 basic_block bb = BASIC_BLOCK (i);
6834 /* Check corectness of edge lists */
6843 "verify_flow_info: Basic block %d succ edge is corrupted\n",
6845 fprintf (stderr, "Predecessor: ");
6846 dump_edge_info (stderr, e, 0);
6847 fprintf (stderr, "\nSuccessor: ");
6848 dump_edge_info (stderr, e, 1);
6852 if (e->dest != EXIT_BLOCK_PTR)
6854 edge e2 = e->dest->pred;
6855 while (e2 && e2 != e)
6859 error ("Basic block %i edge lists are corrupted", bb->index);
6871 error ("Basic block %d pred edge is corrupted", bb->index);
6872 fputs ("Predecessor: ", stderr);
6873 dump_edge_info (stderr, e, 0);
6874 fputs ("\nSuccessor: ", stderr);
6875 dump_edge_info (stderr, e, 1);
6876 fputc ('\n', stderr);
6879 if (e->src != ENTRY_BLOCK_PTR)
6881 edge e2 = e->src->succ;
6882 while (e2 && e2 != e)
6886 error ("Basic block %i edge lists are corrupted", bb->index);
6893 /* OK pointers are correct. Now check the header of basic
6894 block. It ought to contain optional CODE_LABEL followed
6895 by NOTE_BASIC_BLOCK. */
6897 if (GET_CODE (x) == CODE_LABEL)
6901 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6907 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
6909 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6916 /* Do checks for empty blocks here */
6923 if (NOTE_INSN_BASIC_BLOCK_P (x))
6925 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6926 INSN_UID (x), bb->index);
6933 if (GET_CODE (x) == JUMP_INSN
6934 || GET_CODE (x) == CODE_LABEL
6935 || GET_CODE (x) == BARRIER)
6937 error ("In basic block %d:", bb->index);
6938 fatal_insn ("Flow control insn inside a basic block", x);
6946 last_bb_num_seen = -1;
6951 if (NOTE_INSN_BASIC_BLOCK_P (x))
6953 basic_block bb = NOTE_BASIC_BLOCK (x);
6955 if (bb->index != last_bb_num_seen + 1)
6956 /* Basic blocks not numbered consecutively. */
6959 last_bb_num_seen = bb->index;
6962 if (!bb_info[INSN_UID (x)])
6964 switch (GET_CODE (x))
6971 /* An addr_vec is placed outside any block block. */
6973 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
6974 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
6975 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
6980 /* But in any case, non-deletable labels can appear anywhere. */
6984 fatal_insn ("Insn outside basic block", x);
6989 && GET_CODE (x) == JUMP_INSN
6990 && returnjump_p (x) && ! condjump_p (x)
6991 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
6992 fatal_insn ("Return not followed by barrier", x);
6997 if (num_bb_notes != n_basic_blocks)
6999 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
7000 num_bb_notes, n_basic_blocks);
7009 /* Functions to access an edge list with a vector representation.
7010 Enough data is kept such that given an index number, the
7011 pred and succ that edge represents can be determined, or
7012 given a pred and a succ, its index number can be returned.
7013 This allows algorithms which consume a lot of memory to
7014 represent the normally full matrix of edge (pred,succ) with a
7015 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
7016 wasted space in the client code due to sparse flow graphs. */
7018 /* This functions initializes the edge list. Basically the entire
7019 flowgraph is processed, and all edges are assigned a number,
7020 and the data structure is filled in. */
7025 struct edge_list *elist;
7031 block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
7035 /* Determine the number of edges in the flow graph by counting successor
7036 edges on each basic block. */
7037 for (x = 0; x < n_basic_blocks; x++)
7039 basic_block bb = BASIC_BLOCK (x);
7041 for (e = bb->succ; e; e = e->succ_next)
7044 /* Don't forget successors of the entry block. */
7045 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7048 elist = (struct edge_list *) xmalloc (sizeof (struct edge_list));
7049 elist->num_blocks = block_count;
7050 elist->num_edges = num_edges;
7051 elist->index_to_edge = (edge *) xmalloc (sizeof (edge) * num_edges);
7055 /* Follow successors of the entry block, and register these edges. */
7056 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7058 elist->index_to_edge[num_edges] = e;
7062 for (x = 0; x < n_basic_blocks; x++)
7064 basic_block bb = BASIC_BLOCK (x);
7066 /* Follow all successors of blocks, and register these edges. */
7067 for (e = bb->succ; e; e = e->succ_next)
7069 elist->index_to_edge[num_edges] = e;
7076 /* This function free's memory associated with an edge list. */
7079 free_edge_list (elist)
7080 struct edge_list *elist;
7084 free (elist->index_to_edge);
7089 /* This function provides debug output showing an edge list. */
7092 print_edge_list (f, elist)
7094 struct edge_list *elist;
7097 fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
7098 elist->num_blocks - 2, elist->num_edges);
7100 for (x = 0; x < elist->num_edges; x++)
7102 fprintf (f, " %-4d - edge(", x);
7103 if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
7104 fprintf (f, "entry,");
7106 fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
7108 if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
7109 fprintf (f, "exit)\n");
7111 fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
7115 /* This function provides an internal consistency check of an edge list,
7116 verifying that all edges are present, and that there are no
7120 verify_edge_list (f, elist)
7122 struct edge_list *elist;
7124 int x, pred, succ, index;
7127 for (x = 0; x < n_basic_blocks; x++)
7129 basic_block bb = BASIC_BLOCK (x);
7131 for (e = bb->succ; e; e = e->succ_next)
7133 pred = e->src->index;
7134 succ = e->dest->index;
7135 index = EDGE_INDEX (elist, e->src, e->dest);
7136 if (index == EDGE_INDEX_NO_EDGE)
7138 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7141 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7142 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7143 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7144 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7145 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7146 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7149 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
7151 pred = e->src->index;
7152 succ = e->dest->index;
7153 index = EDGE_INDEX (elist, e->src, e->dest);
7154 if (index == EDGE_INDEX_NO_EDGE)
7156 fprintf (f, "*p* No index for edge from %d to %d\n", pred, succ);
7159 if (INDEX_EDGE_PRED_BB (elist, index)->index != pred)
7160 fprintf (f, "*p* Pred for index %d should be %d not %d\n",
7161 index, pred, INDEX_EDGE_PRED_BB (elist, index)->index);
7162 if (INDEX_EDGE_SUCC_BB (elist, index)->index != succ)
7163 fprintf (f, "*p* Succ for index %d should be %d not %d\n",
7164 index, succ, INDEX_EDGE_SUCC_BB (elist, index)->index);
7166 /* We've verified that all the edges are in the list, no lets make sure
7167 there are no spurious edges in the list. */
7169 for (pred = 0; pred < n_basic_blocks; pred++)
7170 for (succ = 0; succ < n_basic_blocks; succ++)
7172 basic_block p = BASIC_BLOCK (pred);
7173 basic_block s = BASIC_BLOCK (succ);
7177 for (e = p->succ; e; e = e->succ_next)
7183 for (e = s->pred; e; e = e->pred_next)
7189 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7190 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7191 fprintf (f, "*** Edge (%d, %d) appears to not have an index\n",
7193 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), BASIC_BLOCK (succ))
7194 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7195 fprintf (f, "*** Edge (%d, %d) has index %d, but there is no edge\n",
7196 pred, succ, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7197 BASIC_BLOCK (succ)));
7199 for (succ = 0; succ < n_basic_blocks; succ++)
7201 basic_block p = ENTRY_BLOCK_PTR;
7202 basic_block s = BASIC_BLOCK (succ);
7206 for (e = p->succ; e; e = e->succ_next)
7212 for (e = s->pred; e; e = e->pred_next)
7218 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7219 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7220 fprintf (f, "*** Edge (entry, %d) appears to not have an index\n",
7222 if (EDGE_INDEX (elist, ENTRY_BLOCK_PTR, BASIC_BLOCK (succ))
7223 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7224 fprintf (f, "*** Edge (entry, %d) has index %d, but no edge exists\n",
7225 succ, EDGE_INDEX (elist, ENTRY_BLOCK_PTR,
7226 BASIC_BLOCK (succ)));
7228 for (pred = 0; pred < n_basic_blocks; pred++)
7230 basic_block p = BASIC_BLOCK (pred);
7231 basic_block s = EXIT_BLOCK_PTR;
7235 for (e = p->succ; e; e = e->succ_next)
7241 for (e = s->pred; e; e = e->pred_next)
7247 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7248 == EDGE_INDEX_NO_EDGE && found_edge != 0)
7249 fprintf (f, "*** Edge (%d, exit) appears to not have an index\n",
7251 if (EDGE_INDEX (elist, BASIC_BLOCK (pred), EXIT_BLOCK_PTR)
7252 != EDGE_INDEX_NO_EDGE && found_edge == 0)
7253 fprintf (f, "*** Edge (%d, exit) has index %d, but no edge exists\n",
7254 pred, EDGE_INDEX (elist, BASIC_BLOCK (pred),
7259 /* This routine will determine what, if any, edge there is between
7260 a specified predecessor and successor. */
7263 find_edge_index (edge_list, pred, succ)
7264 struct edge_list *edge_list;
7265 basic_block pred, succ;
7268 for (x = 0; x < NUM_EDGES (edge_list); x++)
7270 if (INDEX_EDGE_PRED_BB (edge_list, x) == pred
7271 && INDEX_EDGE_SUCC_BB (edge_list, x) == succ)
7274 return (EDGE_INDEX_NO_EDGE);
7277 /* This function will remove an edge from the flow graph. */
7283 edge last_pred = NULL;
7284 edge last_succ = NULL;
7286 basic_block src, dest;
7289 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
7295 last_succ->succ_next = e->succ_next;
7297 src->succ = e->succ_next;
7299 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
7305 last_pred->pred_next = e->pred_next;
7307 dest->pred = e->pred_next;
7313 /* This routine will remove any fake successor edges for a basic block.
7314 When the edge is removed, it is also removed from whatever predecessor
7318 remove_fake_successors (bb)
7322 for (e = bb->succ; e;)
7326 if ((tmp->flags & EDGE_FAKE) == EDGE_FAKE)
7331 /* This routine will remove all fake edges from the flow graph. If
7332 we remove all fake successors, it will automatically remove all
7333 fake predecessors. */
7336 remove_fake_edges ()
7340 for (x = 0; x < n_basic_blocks; x++)
7341 remove_fake_successors (BASIC_BLOCK (x));
7343 /* We've handled all successors except the entry block's. */
7344 remove_fake_successors (ENTRY_BLOCK_PTR);
7347 /* This function will add a fake edge between any block which has no
7348 successors, and the exit block. Some data flow equations require these
7352 add_noreturn_fake_exit_edges ()
7356 for (x = 0; x < n_basic_blocks; x++)
7357 if (BASIC_BLOCK (x)->succ == NULL)
7358 make_edge (NULL, BASIC_BLOCK (x), EXIT_BLOCK_PTR, EDGE_FAKE);
7361 /* This function adds a fake edge between any infinite loops to the
7362 exit block. Some optimizations require a path from each node to
7365 See also Morgan, Figure 3.10, pp. 82-83.
7367 The current implementation is ugly, not attempting to minimize the
7368 number of inserted fake edges. To reduce the number of fake edges
7369 to insert, add fake edges from _innermost_ loops containing only
7370 nodes not reachable from the exit block. */
7373 connect_infinite_loops_to_exit ()
7375 basic_block unvisited_block;
7377 /* Perform depth-first search in the reverse graph to find nodes
7378 reachable from the exit block. */
7379 struct depth_first_search_dsS dfs_ds;
7381 flow_dfs_compute_reverse_init (&dfs_ds);
7382 flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
7384 /* Repeatedly add fake edges, updating the unreachable nodes. */
7387 unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds);
7388 if (!unvisited_block)
7390 make_edge (NULL, unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
7391 flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
7394 flow_dfs_compute_reverse_finish (&dfs_ds);
7399 /* Redirect an edge's successor from one block to another. */
7402 redirect_edge_succ (e, new_succ)
7404 basic_block new_succ;
7408 /* Disconnect the edge from the old successor block. */
7409 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
7411 *pe = (*pe)->pred_next;
7413 /* Reconnect the edge to the new successor block. */
7414 e->pred_next = new_succ->pred;
7419 /* Redirect an edge's predecessor from one block to another. */
7422 redirect_edge_pred (e, new_pred)
7424 basic_block new_pred;
7428 /* Disconnect the edge from the old predecessor block. */
7429 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
7431 *pe = (*pe)->succ_next;
7433 /* Reconnect the edge to the new predecessor block. */
7434 e->succ_next = new_pred->succ;
7439 /* Dump the list of basic blocks in the bitmap NODES. */
7442 flow_nodes_print (str, nodes, file)
7444 const sbitmap nodes;
7452 fprintf (file, "%s { ", str);
7453 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
7454 fputs ("}\n", file);
7458 /* Dump the list of edges in the array EDGE_LIST. */
7461 flow_edge_list_print (str, edge_list, num_edges, file)
7463 const edge *edge_list;
7472 fprintf (file, "%s { ", str);
7473 for (i = 0; i < num_edges; i++)
7474 fprintf (file, "%d->%d ", edge_list[i]->src->index,
7475 edge_list[i]->dest->index);
7476 fputs ("}\n", file);
7480 /* Dump loop related CFG information. */
7483 flow_loops_cfg_dump (loops, file)
7484 const struct loops *loops;
7489 if (! loops->num || ! file || ! loops->cfg.dom)
7492 for (i = 0; i < n_basic_blocks; i++)
7496 fprintf (file, ";; %d succs { ", i);
7497 for (succ = BASIC_BLOCK (i)->succ; succ; succ = succ->succ_next)
7498 fprintf (file, "%d ", succ->dest->index);
7499 flow_nodes_print ("} dom", loops->cfg.dom[i], file);
7502 /* Dump the DFS node order. */
7503 if (loops->cfg.dfs_order)
7505 fputs (";; DFS order: ", file);
7506 for (i = 0; i < n_basic_blocks; i++)
7507 fprintf (file, "%d ", loops->cfg.dfs_order[i]);
7510 /* Dump the reverse completion node order. */
7511 if (loops->cfg.rc_order)
7513 fputs (";; RC order: ", file);
7514 for (i = 0; i < n_basic_blocks; i++)
7515 fprintf (file, "%d ", loops->cfg.rc_order[i]);
7520 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7523 flow_loop_nested_p (outer, loop)
7527 return sbitmap_a_subset_b_p (loop->nodes, outer->nodes);
7531 /* Dump the loop information specified by LOOP to the stream FILE
7532 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7534 flow_loop_dump (loop, file, loop_dump_aux, verbose)
7535 const struct loop *loop;
7537 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7540 if (! loop || ! loop->header)
7543 fprintf (file, ";;\n;; Loop %d (%d to %d):%s%s\n",
7544 loop->num, INSN_UID (loop->first->head),
7545 INSN_UID (loop->last->end),
7546 loop->shared ? " shared" : "",
7547 loop->invalid ? " invalid" : "");
7548 fprintf (file, ";; header %d, latch %d, pre-header %d, first %d, last %d\n",
7549 loop->header->index, loop->latch->index,
7550 loop->pre_header ? loop->pre_header->index : -1,
7551 loop->first->index, loop->last->index);
7552 fprintf (file, ";; depth %d, level %d, outer %ld\n",
7553 loop->depth, loop->level,
7554 (long) (loop->outer ? loop->outer->num : -1));
7556 if (loop->pre_header_edges)
7557 flow_edge_list_print (";; pre-header edges", loop->pre_header_edges,
7558 loop->num_pre_header_edges, file);
7559 flow_edge_list_print (";; entry edges", loop->entry_edges,
7560 loop->num_entries, file);
7561 fprintf (file, ";; %d", loop->num_nodes);
7562 flow_nodes_print (" nodes", loop->nodes, file);
7563 flow_edge_list_print (";; exit edges", loop->exit_edges,
7564 loop->num_exits, file);
7565 if (loop->exits_doms)
7566 flow_nodes_print (";; exit doms", loop->exits_doms, file);
7568 loop_dump_aux (loop, file, verbose);
7572 /* Dump the loop information specified by LOOPS to the stream FILE,
7573 using auxiliary dump callback function LOOP_DUMP_AUX if non null. */
7575 flow_loops_dump (loops, file, loop_dump_aux, verbose)
7576 const struct loops *loops;
7578 void (*loop_dump_aux) PARAMS((const struct loop *, FILE *, int));
7584 num_loops = loops->num;
7585 if (! num_loops || ! file)
7588 fprintf (file, ";; %d loops found, %d levels\n",
7589 num_loops, loops->levels);
7591 for (i = 0; i < num_loops; i++)
7593 struct loop *loop = &loops->array[i];
7595 flow_loop_dump (loop, file, loop_dump_aux, verbose);
7601 for (j = 0; j < i; j++)
7603 struct loop *oloop = &loops->array[j];
7605 if (loop->header == oloop->header)
7610 smaller = loop->num_nodes < oloop->num_nodes;
7612 /* If the union of LOOP and OLOOP is different than
7613 the larger of LOOP and OLOOP then LOOP and OLOOP
7614 must be disjoint. */
7615 disjoint = ! flow_loop_nested_p (smaller ? loop : oloop,
7616 smaller ? oloop : loop);
7618 ";; loop header %d shared by loops %d, %d %s\n",
7619 loop->header->index, i, j,
7620 disjoint ? "disjoint" : "nested");
7627 flow_loops_cfg_dump (loops, file);
7631 /* Free all the memory allocated for LOOPS. */
7634 flow_loops_free (loops)
7635 struct loops *loops;
7644 /* Free the loop descriptors. */
7645 for (i = 0; i < loops->num; i++)
7647 struct loop *loop = &loops->array[i];
7649 if (loop->pre_header_edges)
7650 free (loop->pre_header_edges);
7652 sbitmap_free (loop->nodes);
7653 if (loop->entry_edges)
7654 free (loop->entry_edges);
7655 if (loop->exit_edges)
7656 free (loop->exit_edges);
7657 if (loop->exits_doms)
7658 sbitmap_free (loop->exits_doms);
7660 free (loops->array);
7661 loops->array = NULL;
7664 sbitmap_vector_free (loops->cfg.dom);
7665 if (loops->cfg.dfs_order)
7666 free (loops->cfg.dfs_order);
7668 if (loops->shared_headers)
7669 sbitmap_free (loops->shared_headers);
7674 /* Find the entry edges into the loop with header HEADER and nodes
7675 NODES and store in ENTRY_EDGES array. Return the number of entry
7676 edges from the loop. */
7679 flow_loop_entry_edges_find (header, nodes, entry_edges)
7681 const sbitmap nodes;
7687 *entry_edges = NULL;
7690 for (e = header->pred; e; e = e->pred_next)
7692 basic_block src = e->src;
7694 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7701 *entry_edges = (edge *) xmalloc (num_entries * sizeof (edge *));
7704 for (e = header->pred; e; e = e->pred_next)
7706 basic_block src = e->src;
7708 if (src == ENTRY_BLOCK_PTR || ! TEST_BIT (nodes, src->index))
7709 (*entry_edges)[num_entries++] = e;
7716 /* Find the exit edges from the loop using the bitmap of loop nodes
7717 NODES and store in EXIT_EDGES array. Return the number of
7718 exit edges from the loop. */
7721 flow_loop_exit_edges_find (nodes, exit_edges)
7722 const sbitmap nodes;
7731 /* Check all nodes within the loop to see if there are any
7732 successors not in the loop. Note that a node may have multiple
7733 exiting edges ????? A node can have one jumping edge and one fallthru
7734 edge so only one of these can exit the loop. */
7736 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7737 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7739 basic_block dest = e->dest;
7741 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7749 *exit_edges = (edge *) xmalloc (num_exits * sizeof (edge *));
7751 /* Store all exiting edges into an array. */
7753 EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {
7754 for (e = BASIC_BLOCK (node)->succ; e; e = e->succ_next)
7756 basic_block dest = e->dest;
7758 if (dest == EXIT_BLOCK_PTR || ! TEST_BIT (nodes, dest->index))
7759 (*exit_edges)[num_exits++] = e;
7767 /* Find the nodes contained within the loop with header HEADER and
7768 latch LATCH and store in NODES. Return the number of nodes within
7772 flow_loop_nodes_find (header, latch, nodes)
7781 stack = (basic_block *) xmalloc (n_basic_blocks * sizeof (basic_block));
7784 /* Start with only the loop header in the set of loop nodes. */
7785 sbitmap_zero (nodes);
7786 SET_BIT (nodes, header->index);
7788 header->loop_depth++;
7790 /* Push the loop latch on to the stack. */
7791 if (! TEST_BIT (nodes, latch->index))
7793 SET_BIT (nodes, latch->index);
7794 latch->loop_depth++;
7796 stack[sp++] = latch;
7805 for (e = node->pred; e; e = e->pred_next)
7807 basic_block ancestor = e->src;
7809 /* If each ancestor not marked as part of loop, add to set of
7810 loop nodes and push on to stack. */
7811 if (ancestor != ENTRY_BLOCK_PTR
7812 && ! TEST_BIT (nodes, ancestor->index))
7814 SET_BIT (nodes, ancestor->index);
7815 ancestor->loop_depth++;
7817 stack[sp++] = ancestor;
7825 /* Compute the depth first search order and store in the array
7826 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7827 RC_ORDER is non-zero, return the reverse completion number for each
7828 node. Returns the number of nodes visited. A depth first search
7829 tries to get as far away from the starting point as quickly as
7833 flow_depth_first_order_compute (dfs_order, rc_order)
7840 int rcnum = n_basic_blocks - 1;
7843 /* Allocate stack for back-tracking up CFG. */
7844 stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge));
7847 /* Allocate bitmap to track nodes that have been visited. */
7848 visited = sbitmap_alloc (n_basic_blocks);
7850 /* None of the nodes in the CFG have been visited yet. */
7851 sbitmap_zero (visited);
7853 /* Push the first edge on to the stack. */
7854 stack[sp++] = ENTRY_BLOCK_PTR->succ;
7862 /* Look at the edge on the top of the stack. */
7867 /* Check if the edge destination has been visited yet. */
7868 if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
7870 /* Mark that we have visited the destination. */
7871 SET_BIT (visited, dest->index);
7874 dfs_order[dfsnum++] = dest->index;
7878 /* Since the DEST node has been visited for the first
7879 time, check its successors. */
7880 stack[sp++] = dest->succ;
7884 /* There are no successors for the DEST node so assign
7885 its reverse completion number. */
7887 rc_order[rcnum--] = dest->index;
7892 if (! e->succ_next && src != ENTRY_BLOCK_PTR)
7894 /* There are no more successors for the SRC node
7895 so assign its reverse completion number. */
7897 rc_order[rcnum--] = src->index;
7901 stack[sp - 1] = e->succ_next;
7908 sbitmap_free (visited);
7910 /* The number of nodes visited should not be greater than
7912 if (dfsnum > n_basic_blocks)
7915 /* There are some nodes left in the CFG that are unreachable. */
7916 if (dfsnum < n_basic_blocks)
7921 /* Compute the depth first search order on the _reverse_ graph and
7922 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7923 Returns the number of nodes visited.
7925 The computation is split into three pieces:
7927 flow_dfs_compute_reverse_init () creates the necessary data
7930 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7931 structures. The block will start the search.
7933 flow_dfs_compute_reverse_execute () continues (or starts) the
7934 search using the block on the top of the stack, stopping when the
7937 flow_dfs_compute_reverse_finish () destroys the necessary data
7940 Thus, the user will probably call ..._init(), call ..._add_bb() to
7941 add a beginning basic block to the stack, call ..._execute(),
7942 possibly add another bb to the stack and again call ..._execute(),
7943 ..., and finally call _finish(). */
7945 /* Initialize the data structures used for depth-first search on the
7946 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7947 added to the basic block stack. DATA is the current depth-first
7948 search context. If INITIALIZE_STACK is non-zero, there is an
7949 element on the stack. */
7952 flow_dfs_compute_reverse_init (data)
7953 depth_first_search_ds data;
7955 /* Allocate stack for back-tracking up CFG. */
7957 (basic_block *) xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
7958 * sizeof (basic_block));
7961 /* Allocate bitmap to track nodes that have been visited. */
7962 data->visited_blocks = sbitmap_alloc (n_basic_blocks - (INVALID_BLOCK + 1));
7964 /* None of the nodes in the CFG have been visited yet. */
7965 sbitmap_zero (data->visited_blocks);
7970 /* Add the specified basic block to the top of the dfs data
7971 structures. When the search continues, it will start at the
7975 flow_dfs_compute_reverse_add_bb (data, bb)
7976 depth_first_search_ds data;
7979 data->stack[data->sp++] = bb;
7983 /* Continue the depth-first search through the reverse graph starting
7984 with the block at the stack's top and ending when the stack is
7985 empty. Visited nodes are marked. Returns an unvisited basic
7986 block, or NULL if there is none available. */
7989 flow_dfs_compute_reverse_execute (data)
7990 depth_first_search_ds data;
7996 while (data->sp > 0)
7998 bb = data->stack[--data->sp];
8000 /* Mark that we have visited this node. */
8001 if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
8003 SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
8005 /* Perform depth-first search on adjacent vertices. */
8006 for (e = bb->pred; e; e = e->pred_next)
8007 flow_dfs_compute_reverse_add_bb (data, e->src);
8011 /* Determine if there are unvisited basic blocks. */
8012 for (i = n_basic_blocks - (INVALID_BLOCK + 1); --i >= 0;)
8013 if (!TEST_BIT (data->visited_blocks, i))
8014 return BASIC_BLOCK (i + (INVALID_BLOCK + 1));
8018 /* Destroy the data structures needed for depth-first search on the
8022 flow_dfs_compute_reverse_finish (data)
8023 depth_first_search_ds data;
8026 sbitmap_free (data->visited_blocks);
8031 /* Find the root node of the loop pre-header extended basic block and
8032 the edges along the trace from the root node to the loop header. */
8035 flow_loop_pre_header_scan (loop)
8041 loop->num_pre_header_edges = 0;
8043 if (loop->num_entries != 1)
8046 ebb = loop->entry_edges[0]->src;
8048 if (ebb != ENTRY_BLOCK_PTR)
8052 /* Count number of edges along trace from loop header to
8053 root of pre-header extended basic block. Usually this is
8054 only one or two edges. */
8056 while (ebb->pred->src != ENTRY_BLOCK_PTR && ! ebb->pred->pred_next)
8058 ebb = ebb->pred->src;
8062 loop->pre_header_edges = (edge *) xmalloc (num * sizeof (edge *));
8063 loop->num_pre_header_edges = num;
8065 /* Store edges in order that they are followed. The source
8066 of the first edge is the root node of the pre-header extended
8067 basic block and the destination of the last last edge is
8069 for (e = loop->entry_edges[0]; num; e = e->src->pred)
8071 loop->pre_header_edges[--num] = e;
8077 /* Return the block for the pre-header of the loop with header
8078 HEADER where DOM specifies the dominator information. Return NULL if
8079 there is no pre-header. */
8082 flow_loop_pre_header_find (header, dom)
8086 basic_block pre_header;
8089 /* If block p is a predecessor of the header and is the only block
8090 that the header does not dominate, then it is the pre-header. */
8092 for (e = header->pred; e; e = e->pred_next)
8094 basic_block node = e->src;
8096 if (node != ENTRY_BLOCK_PTR
8097 && ! TEST_BIT (dom[node->index], header->index))
8099 if (pre_header == NULL)
8103 /* There are multiple edges into the header from outside
8104 the loop so there is no pre-header block. */
8113 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
8114 previously added. The insertion algorithm assumes that the loops
8115 are added in the order found by a depth first search of the CFG. */
8118 flow_loop_tree_node_add (prevloop, loop)
8119 struct loop *prevloop;
8123 if (flow_loop_nested_p (prevloop, loop))
8125 prevloop->inner = loop;
8126 loop->outer = prevloop;
8130 while (prevloop->outer)
8132 if (flow_loop_nested_p (prevloop->outer, loop))
8134 prevloop->next = loop;
8135 loop->outer = prevloop->outer;
8138 prevloop = prevloop->outer;
8141 prevloop->next = loop;
8145 /* Build the loop hierarchy tree for LOOPS. */
8148 flow_loops_tree_build (loops)
8149 struct loops *loops;
8154 num_loops = loops->num;
8158 /* Root the loop hierarchy tree with the first loop found.
8159 Since we used a depth first search this should be the
8161 loops->tree = &loops->array[0];
8162 loops->tree->outer = loops->tree->inner = loops->tree->next = NULL;
8164 /* Add the remaining loops to the tree. */
8165 for (i = 1; i < num_loops; i++)
8166 flow_loop_tree_node_add (&loops->array[i - 1], &loops->array[i]);
8169 /* Helper function to compute loop nesting depth and enclosed loop level
8170 for the natural loop specified by LOOP at the loop depth DEPTH.
8171 Returns the loop level. */
8174 flow_loop_level_compute (loop, depth)
8184 /* Traverse loop tree assigning depth and computing level as the
8185 maximum level of all the inner loops of this loop. The loop
8186 level is equivalent to the height of the loop in the loop tree
8187 and corresponds to the number of enclosed loop levels (including
8189 for (inner = loop->inner; inner; inner = inner->next)
8193 ilevel = flow_loop_level_compute (inner, depth + 1) + 1;
8198 loop->level = level;
8199 loop->depth = depth;
8203 /* Compute the loop nesting depth and enclosed loop level for the loop
8204 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
8208 flow_loops_level_compute (loops)
8209 struct loops *loops;
8215 /* Traverse all the outer level loops. */
8216 for (loop = loops->tree; loop; loop = loop->next)
8218 level = flow_loop_level_compute (loop, 1);
8226 /* Scan a single natural loop specified by LOOP collecting information
8227 about it specified by FLAGS. */
8230 flow_loop_scan (loops, loop, flags)
8231 struct loops *loops;
8235 /* Determine prerequisites. */
8236 if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
8237 flags |= LOOP_EXIT_EDGES;
8239 if (flags & LOOP_ENTRY_EDGES)
8241 /* Find edges which enter the loop header.
8242 Note that the entry edges should only
8243 enter the header of a natural loop. */
8245 = flow_loop_entry_edges_find (loop->header,
8247 &loop->entry_edges);
8250 if (flags & LOOP_EXIT_EDGES)
8252 /* Find edges which exit the loop. */
8254 = flow_loop_exit_edges_find (loop->nodes,
8258 if (flags & LOOP_EXITS_DOMS)
8262 /* Determine which loop nodes dominate all the exits
8264 loop->exits_doms = sbitmap_alloc (n_basic_blocks);
8265 sbitmap_copy (loop->exits_doms, loop->nodes);
8266 for (j = 0; j < loop->num_exits; j++)
8267 sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
8268 loops->cfg.dom[loop->exit_edges[j]->src->index]);
8270 /* The header of a natural loop must dominate
8272 if (! TEST_BIT (loop->exits_doms, loop->header->index))
8276 if (flags & LOOP_PRE_HEADER)
8278 /* Look to see if the loop has a pre-header node. */
8280 = flow_loop_pre_header_find (loop->header, loops->cfg.dom);
8282 /* Find the blocks within the extended basic block of
8283 the loop pre-header. */
8284 flow_loop_pre_header_scan (loop);
8290 /* Find all the natural loops in the function and save in LOOPS structure
8291 and recalculate loop_depth information in basic block structures.
8292 FLAGS controls which loop information is collected.
8293 Return the number of natural loops found. */
8296 flow_loops_find (loops, flags)
8297 struct loops *loops;
8309 /* This function cannot be repeatedly called with different
8310 flags to build up the loop information. The loop tree
8311 must always be built if this function is called. */
8312 if (! (flags & LOOP_TREE))
8315 memset (loops, 0, sizeof (*loops));
8317 /* Taking care of this degenerate case makes the rest of
8318 this code simpler. */
8319 if (n_basic_blocks == 0)
8325 /* Compute the dominators. */
8326 dom = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
8327 calculate_dominance_info (NULL, dom, CDI_DOMINATORS);
8329 /* Count the number of loop edges (back edges). This should be the
8330 same as the number of natural loops. */
8333 for (b = 0; b < n_basic_blocks; b++)
8337 header = BASIC_BLOCK (b);
8338 header->loop_depth = 0;
8340 for (e = header->pred; e; e = e->pred_next)
8342 basic_block latch = e->src;
8344 /* Look for back edges where a predecessor is dominated
8345 by this block. A natural loop has a single entry
8346 node (header) that dominates all the nodes in the
8347 loop. It also has single back edge to the header
8348 from a latch node. Note that multiple natural loops
8349 may share the same header. */
8350 if (b != header->index)
8353 if (latch != ENTRY_BLOCK_PTR && TEST_BIT (dom[latch->index], b))
8360 /* Compute depth first search order of the CFG so that outer
8361 natural loops will be found before inner natural loops. */
8362 dfs_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8363 rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
8364 flow_depth_first_order_compute (dfs_order, rc_order);
8366 /* Save CFG derived information to avoid recomputing it. */
8367 loops->cfg.dom = dom;
8368 loops->cfg.dfs_order = dfs_order;
8369 loops->cfg.rc_order = rc_order;
8371 /* Allocate loop structures. */
8373 = (struct loop *) xcalloc (num_loops, sizeof (struct loop));
8375 headers = sbitmap_alloc (n_basic_blocks);
8376 sbitmap_zero (headers);
8378 loops->shared_headers = sbitmap_alloc (n_basic_blocks);
8379 sbitmap_zero (loops->shared_headers);
8381 /* Find and record information about all the natural loops
8384 for (b = 0; b < n_basic_blocks; b++)
8388 /* Search the nodes of the CFG in reverse completion order
8389 so that we can find outer loops first. */
8390 header = BASIC_BLOCK (rc_order[b]);
8392 /* Look for all the possible latch blocks for this header. */
8393 for (e = header->pred; e; e = e->pred_next)
8395 basic_block latch = e->src;
8397 /* Look for back edges where a predecessor is dominated
8398 by this block. A natural loop has a single entry
8399 node (header) that dominates all the nodes in the
8400 loop. It also has single back edge to the header
8401 from a latch node. Note that multiple natural loops
8402 may share the same header. */
8403 if (latch != ENTRY_BLOCK_PTR
8404 && TEST_BIT (dom[latch->index], header->index))
8408 loop = loops->array + num_loops;
8410 loop->header = header;
8411 loop->latch = latch;
8412 loop->num = num_loops;
8419 for (i = 0; i < num_loops; i++)
8421 struct loop *loop = &loops->array[i];
8423 /* Keep track of blocks that are loop headers so
8424 that we can tell which loops should be merged. */
8425 if (TEST_BIT (headers, loop->header->index))
8426 SET_BIT (loops->shared_headers, loop->header->index);
8427 SET_BIT (headers, loop->header->index);
8429 /* Find nodes contained within the loop. */
8430 loop->nodes = sbitmap_alloc (n_basic_blocks);
8432 = flow_loop_nodes_find (loop->header, loop->latch, loop->nodes);
8434 /* Compute first and last blocks within the loop.
8435 These are often the same as the loop header and
8436 loop latch respectively, but this is not always
8439 = BASIC_BLOCK (sbitmap_first_set_bit (loop->nodes));
8441 = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
8443 flow_loop_scan (loops, loop, flags);
8446 /* Natural loops with shared headers may either be disjoint or
8447 nested. Disjoint loops with shared headers cannot be inner
8448 loops and should be merged. For now just mark loops that share
8450 for (i = 0; i < num_loops; i++)
8451 if (TEST_BIT (loops->shared_headers, loops->array[i].header->index))
8452 loops->array[i].shared = 1;
8454 sbitmap_free (headers);
8457 loops->num = num_loops;
8459 /* Build the loop hierarchy tree. */
8460 flow_loops_tree_build (loops);
8462 /* Assign the loop nesting depth and enclosed loop level for each
8464 loops->levels = flow_loops_level_compute (loops);
8470 /* Update the information regarding the loops in the CFG
8471 specified by LOOPS. */
8473 flow_loops_update (loops, flags)
8474 struct loops *loops;
8477 /* One day we may want to update the current loop data. For now
8478 throw away the old stuff and rebuild what we need. */
8480 flow_loops_free (loops);
8482 return flow_loops_find (loops, flags);
8486 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
8489 flow_loop_outside_edge_p (loop, e)
8490 const struct loop *loop;
8493 if (e->dest != loop->header)
8495 return (e->src == ENTRY_BLOCK_PTR)
8496 || ! TEST_BIT (loop->nodes, e->src->index);
8499 /* Clear LOG_LINKS fields of insns in a chain.
8500 Also clear the global_live_at_{start,end} fields of the basic block
8504 clear_log_links (insns)
8510 for (i = insns; i; i = NEXT_INSN (i))
8514 for (b = 0; b < n_basic_blocks; b++)
8516 basic_block bb = BASIC_BLOCK (b);
8518 bb->global_live_at_start = NULL;
8519 bb->global_live_at_end = NULL;
8522 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
8523 EXIT_BLOCK_PTR->global_live_at_start = NULL;
8526 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
8527 correspond to the hard registers, if any, set in that map. This
8528 could be done far more efficiently by having all sorts of special-cases
8529 with moving single words, but probably isn't worth the trouble. */
8532 reg_set_to_hard_reg_set (to, from)
8538 EXECUTE_IF_SET_IN_BITMAP
8541 if (i >= FIRST_PSEUDO_REGISTER)
8543 SET_HARD_REG_BIT (*to, i);
8547 /* Called once at intialization time. */
8552 static int initialized;
8556 gcc_obstack_init (&flow_obstack);
8557 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
8562 obstack_free (&flow_obstack, flow_firstobj);
8563 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);