1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
23 /* This file contains the data flow analysis pass of the compiler. It
24 computes data flow information which tells combine_instructions
25 which insns to consider combining and controls register allocation.
27 Additional data flow information that is too bulky to record is
28 generated during the analysis, and is used at that time to create
29 autoincrement and autodecrement addressing.
31 The first step is dividing the function into basic blocks.
32 find_basic_blocks does this. Then life_analysis determines
33 where each register is live and where it is dead.
35 ** find_basic_blocks **
37 find_basic_blocks divides the current function's rtl into basic
38 blocks and constructs the CFG. The blocks are recorded in the
39 basic_block_info array; the CFG exists in the edge structures
40 referenced by the blocks.
42 find_basic_blocks also finds any unreachable loops and deletes them.
46 life_analysis is called immediately after find_basic_blocks.
47 It uses the basic block information to determine where each
48 hard or pseudo register is live.
50 ** live-register info **
52 The information about where each register is live is in two parts:
53 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
55 basic_block->global_live_at_start has an element for each basic
56 block, and the element is a bit-vector with a bit for each hard or
57 pseudo register. The bit is 1 if the register is live at the
58 beginning of the basic block.
60 Two types of elements can be added to an insn's REG_NOTES.
61 A REG_DEAD note is added to an insn's REG_NOTES for any register
62 that meets both of two conditions: The value in the register is not
63 needed in subsequent insns and the insn does not replace the value in
64 the register (in the case of multi-word hard registers, the value in
65 each register must be replaced by the insn to avoid a REG_DEAD note).
67 In the vast majority of cases, an object in a REG_DEAD note will be
68 used somewhere in the insn. The (rare) exception to this is if an
69 insn uses a multi-word hard register and only some of the registers are
70 needed in subsequent insns. In that case, REG_DEAD notes will be
71 provided for those hard registers that are not subsequently needed.
72 Partial REG_DEAD notes of this type do not occur when an insn sets
73 only some of the hard registers used in such a multi-word operand;
74 omitting REG_DEAD notes for objects stored in an insn is optional and
75 the desire to do so does not justify the complexity of the partial
78 REG_UNUSED notes are added for each register that is set by the insn
79 but is unused subsequently (if every register set by the insn is unused
80 and the insn does not reference memory or have some other side-effect,
81 the insn is deleted instead). If only part of a multi-word hard
82 register is used in a subsequent insn, REG_UNUSED notes are made for
83 the parts that will not be used.
85 To determine which registers are live after any insn, one can
86 start from the beginning of the basic block and scan insns, noting
87 which registers are set by each insn and which die there.
89 ** Other actions of life_analysis **
91 life_analysis sets up the LOG_LINKS fields of insns because the
92 information needed to do so is readily available.
94 life_analysis deletes insns whose only effect is to store a value
97 life_analysis notices cases where a reference to a register as
98 a memory address can be combined with a preceding or following
99 incrementation or decrementation of the register. The separate
100 instruction to increment or decrement is deleted and the address
101 is changed to a POST_INC or similar rtx.
103 Each time an incrementing or decrementing address is created,
104 a REG_INC element is added to the insn's REG_NOTES list.
106 life_analysis fills in certain vectors containing information about
107 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
108 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
110 life_analysis sets current_function_sp_is_unchanging if the function
111 doesn't modify the stack pointer. */
115 Split out from life_analysis:
116 - local property discovery (bb->local_live, bb->local_set)
117 - global property computation
119 - pre/post modify transformation
127 #include "hard-reg-set.h"
128 #include "basic-block.h"
129 #include "insn-config.h"
133 #include "function.h"
137 #include "insn-flags.h"
142 #include "splay-tree.h"
144 #define obstack_chunk_alloc xmalloc
145 #define obstack_chunk_free free
148 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
149 the stack pointer does not matter. The value is tested only in
150 functions that have frame pointers.
151 No definition is equivalent to always zero. */
152 #ifndef EXIT_IGNORE_STACK
153 #define EXIT_IGNORE_STACK 0
156 #ifndef HAVE_epilogue
157 #define HAVE_epilogue 0
159 #ifndef HAVE_prologue
160 #define HAVE_prologue 0
162 #ifndef HAVE_sibcall_epilogue
163 #define HAVE_sibcall_epilogue 0
166 /* The contents of the current function definition are allocated
167 in this obstack, and all are freed at the end of the function.
168 For top-level functions, this is temporary_obstack.
169 Separate obstacks are made for nested functions. */
171 extern struct obstack
*function_obstack
;
173 /* Number of basic blocks in the current function. */
177 /* Number of edges in the current function. */
181 /* The basic block array. */
183 varray_type basic_block_info
;
185 /* The special entry and exit blocks. */
187 struct basic_block_def entry_exit_blocks
[2]
192 NULL
, /* local_set */
193 NULL
, /* global_live_at_start */
194 NULL
, /* global_live_at_end */
196 ENTRY_BLOCK
, /* index */
198 -1, -1, /* eh_beg, eh_end */
206 NULL
, /* local_set */
207 NULL
, /* global_live_at_start */
208 NULL
, /* global_live_at_end */
210 EXIT_BLOCK
, /* index */
212 -1, -1, /* eh_beg, eh_end */
217 /* Nonzero if the second flow pass has completed. */
220 /* Maximum register number used in this function, plus one. */
224 /* Indexed by n, giving various register information */
226 varray_type reg_n_info
;
228 /* Size of a regset for the current function,
229 in (1) bytes and (2) elements. */
234 /* Regset of regs live when calls to `setjmp'-like functions happen. */
235 /* ??? Does this exist only for the setjmp-clobbered warning message? */
237 regset regs_live_at_setjmp
;
239 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
240 that have to go in the same hard reg.
241 The first two regs in the list are a pair, and the next two
242 are another pair, etc. */
245 /* Set of registers that may be eliminable. These are handled specially
246 in updating regs_ever_live. */
248 static HARD_REG_SET elim_reg_set
;
250 /* The basic block structure for every insn, indexed by uid. */
252 varray_type basic_block_for_insn
;
254 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
255 /* ??? Should probably be using LABEL_NUSES instead. It would take a
256 bit of surgery to be able to use or co-opt the routines in jump. */
258 static rtx label_value_list
;
259 static rtx tail_recursion_label_list
;
261 /* Holds information for tracking conditional register life information. */
262 struct reg_cond_life_info
264 /* An EXPR_LIST of conditions under which a register is dead. */
267 /* ??? Could store mask of bytes that are dead, so that we could finally
268 track lifetimes of multi-word registers accessed via subregs. */
271 /* For use in communicating between propagate_block and its subroutines.
272 Holds all information needed to compute life and def-use information. */
274 struct propagate_block_info
276 /* The basic block we're considering. */
279 /* Bit N is set if register N is conditionally or unconditionally live. */
282 /* Bit N is set if register N is set this insn. */
285 /* Element N is the next insn that uses (hard or pseudo) register N
286 within the current basic block; or zero, if there is no such insn. */
289 /* Contains a list of all the MEMs we are tracking for dead store
293 /* If non-null, record the set of registers set in the basic block. */
296 #ifdef HAVE_conditional_execution
297 /* Indexed by register number, holds a reg_cond_life_info for each
298 register that is not unconditionally live or dead. */
299 splay_tree reg_cond_dead
;
301 /* Bit N is set if register N is in an expression in reg_cond_dead. */
305 /* Non-zero if the value of CC0 is live. */
308 /* Flags controling the set of information propagate_block collects. */
312 /* Store the data structures necessary for depth-first search. */
313 struct depth_first_search_dsS
{
314 /* stack for backtracking during the algorithm */
317 /* number of edges in the stack. That is, positions 0, ..., sp-1
321 /* record of basic blocks already seen by depth-first search */
322 sbitmap visited_blocks
;
324 typedef struct depth_first_search_dsS
*depth_first_search_ds
;
326 /* Forward declarations */
327 static int count_basic_blocks
PARAMS ((rtx
));
328 static void find_basic_blocks_1
PARAMS ((rtx
));
329 static rtx find_label_refs
PARAMS ((rtx
, rtx
));
330 static void clear_edges
PARAMS ((void));
331 static void make_edges
PARAMS ((rtx
));
332 static void make_label_edge
PARAMS ((sbitmap
*, basic_block
,
334 static void make_eh_edge
PARAMS ((sbitmap
*, eh_nesting_info
*,
335 basic_block
, rtx
, int));
336 static void mark_critical_edges
PARAMS ((void));
337 static void move_stray_eh_region_notes
PARAMS ((void));
338 static void record_active_eh_regions
PARAMS ((rtx
));
340 static void commit_one_edge_insertion
PARAMS ((edge
));
342 static void delete_unreachable_blocks
PARAMS ((void));
343 static void delete_eh_regions
PARAMS ((void));
344 static int can_delete_note_p
PARAMS ((rtx
));
345 static void expunge_block
PARAMS ((basic_block
));
346 static int can_delete_label_p
PARAMS ((rtx
));
347 static int tail_recursion_label_p
PARAMS ((rtx
));
348 static int merge_blocks_move_predecessor_nojumps
PARAMS ((basic_block
,
350 static int merge_blocks_move_successor_nojumps
PARAMS ((basic_block
,
352 static int merge_blocks
PARAMS ((edge
,basic_block
,basic_block
));
353 static void try_merge_blocks
PARAMS ((void));
354 static void tidy_fallthru_edges
PARAMS ((void));
355 static int verify_wide_reg_1
PARAMS ((rtx
*, void *));
356 static void verify_wide_reg
PARAMS ((int, rtx
, rtx
));
357 static void verify_local_live_at_start
PARAMS ((regset
, basic_block
));
358 static int set_noop_p
PARAMS ((rtx
));
359 static int noop_move_p
PARAMS ((rtx
));
360 static void delete_noop_moves
PARAMS ((rtx
));
361 static void notice_stack_pointer_modification_1
PARAMS ((rtx
, rtx
, void *));
362 static void notice_stack_pointer_modification
PARAMS ((rtx
));
363 static void mark_reg
PARAMS ((rtx
, void *));
364 static void mark_regs_live_at_end
PARAMS ((regset
));
365 static int set_phi_alternative_reg
PARAMS ((rtx
, int, int, void *));
366 static void calculate_global_regs_live
PARAMS ((sbitmap
, sbitmap
, int));
367 static void propagate_block_delete_insn
PARAMS ((basic_block
, rtx
));
368 static rtx propagate_block_delete_libcall
PARAMS ((basic_block
, rtx
, rtx
));
369 static int insn_dead_p
PARAMS ((struct propagate_block_info
*,
371 static int libcall_dead_p
PARAMS ((struct propagate_block_info
*,
373 static void mark_set_regs
PARAMS ((struct propagate_block_info
*,
375 static void mark_set_1
PARAMS ((struct propagate_block_info
*,
376 enum rtx_code
, rtx
, rtx
,
378 #ifdef HAVE_conditional_execution
379 static int mark_regno_cond_dead
PARAMS ((struct propagate_block_info
*,
381 static void free_reg_cond_life_info
PARAMS ((splay_tree_value
));
382 static int flush_reg_cond_reg_1
PARAMS ((splay_tree_node
, void *));
383 static void flush_reg_cond_reg
PARAMS ((struct propagate_block_info
*,
385 static rtx ior_reg_cond
PARAMS ((rtx
, rtx
));
386 static rtx not_reg_cond
PARAMS ((rtx
));
387 static rtx nand_reg_cond
PARAMS ((rtx
, rtx
));
390 static void attempt_auto_inc
PARAMS ((struct propagate_block_info
*,
391 rtx
, rtx
, rtx
, rtx
, rtx
));
392 static void find_auto_inc
PARAMS ((struct propagate_block_info
*,
394 static int try_pre_increment_1
PARAMS ((struct propagate_block_info
*,
396 static int try_pre_increment
PARAMS ((rtx
, rtx
, HOST_WIDE_INT
));
398 static void mark_used_reg
PARAMS ((struct propagate_block_info
*,
400 static void mark_used_regs
PARAMS ((struct propagate_block_info
*,
402 void dump_flow_info
PARAMS ((FILE *));
403 void debug_flow_info
PARAMS ((void));
404 static void dump_edge_info
PARAMS ((FILE *, edge
, int));
406 static void invalidate_mems_from_autoinc
PARAMS ((struct propagate_block_info
*,
408 static void remove_fake_successors
PARAMS ((basic_block
));
409 static void flow_nodes_print
PARAMS ((const char *, const sbitmap
, FILE *));
410 static void flow_exits_print
PARAMS ((const char *, const edge
*, int, FILE *));
411 static void flow_loops_cfg_dump
PARAMS ((const struct loops
*, FILE *));
412 static int flow_loop_nested_p
PARAMS ((struct loop
*, struct loop
*));
413 static int flow_loop_exits_find
PARAMS ((const sbitmap
, edge
**));
414 static int flow_loop_nodes_find
PARAMS ((basic_block
, basic_block
, sbitmap
));
415 static int flow_depth_first_order_compute
PARAMS ((int *, int *));
416 static void flow_dfs_compute_reverse_init
417 PARAMS ((depth_first_search_ds
));
418 static void flow_dfs_compute_reverse_add_bb
419 PARAMS ((depth_first_search_ds
, basic_block
));
420 static basic_block flow_dfs_compute_reverse_execute
421 PARAMS ((depth_first_search_ds
));
422 static void flow_dfs_compute_reverse_finish
423 PARAMS ((depth_first_search_ds
));
424 static basic_block flow_loop_pre_header_find
PARAMS ((basic_block
, const sbitmap
*));
425 static void flow_loop_tree_node_add
PARAMS ((struct loop
*, struct loop
*));
426 static void flow_loops_tree_build
PARAMS ((struct loops
*));
427 static int flow_loop_level_compute
PARAMS ((struct loop
*, int));
428 static int flow_loops_level_compute
PARAMS ((struct loops
*));
430 /* Find basic blocks of the current function.
431 F is the first insn of the function and NREGS the number of register
435 find_basic_blocks (f
, nregs
, file
)
437 int nregs ATTRIBUTE_UNUSED
;
438 FILE *file ATTRIBUTE_UNUSED
;
442 /* Flush out existing data. */
443 if (basic_block_info
!= NULL
)
449 /* Clear bb->aux on all extant basic blocks. We'll use this as a
450 tag for reuse during create_basic_block, just in case some pass
451 copies around basic block notes improperly. */
452 for (i
= 0; i
< n_basic_blocks
; ++i
)
453 BASIC_BLOCK (i
)->aux
= NULL
;
455 VARRAY_FREE (basic_block_info
);
458 n_basic_blocks
= count_basic_blocks (f
);
460 /* Size the basic block table. The actual structures will be allocated
461 by find_basic_blocks_1, since we want to keep the structure pointers
462 stable across calls to find_basic_blocks. */
463 /* ??? This whole issue would be much simpler if we called find_basic_blocks
464 exactly once, and thereafter we don't have a single long chain of
465 instructions at all until close to the end of compilation when we
466 actually lay them out. */
468 VARRAY_BB_INIT (basic_block_info
, n_basic_blocks
, "basic_block_info");
470 find_basic_blocks_1 (f
);
472 /* Record the block to which an insn belongs. */
473 /* ??? This should be done another way, by which (perhaps) a label is
474 tagged directly with the basic block that it starts. It is used for
475 more than that currently, but IMO that is the only valid use. */
477 max_uid
= get_max_uid ();
479 /* Leave space for insns life_analysis makes in some cases for auto-inc.
480 These cases are rare, so we don't need too much space. */
481 max_uid
+= max_uid
/ 10;
484 compute_bb_for_insn (max_uid
);
486 /* Discover the edges of our cfg. */
487 record_active_eh_regions (f
);
488 make_edges (label_value_list
);
490 /* Do very simple cleanup now, for the benefit of code that runs between
491 here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
492 tidy_fallthru_edges ();
494 mark_critical_edges ();
496 #ifdef ENABLE_CHECKING
501 /* Count the basic blocks of the function. */
504 count_basic_blocks (f
)
508 register RTX_CODE prev_code
;
509 register int count
= 0;
511 int call_had_abnormal_edge
= 0;
513 prev_code
= JUMP_INSN
;
514 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
516 register RTX_CODE code
= GET_CODE (insn
);
518 if (code
== CODE_LABEL
519 || (GET_RTX_CLASS (code
) == 'i'
520 && (prev_code
== JUMP_INSN
521 || prev_code
== BARRIER
522 || (prev_code
== CALL_INSN
&& call_had_abnormal_edge
))))
525 /* Record whether this call created an edge. */
526 if (code
== CALL_INSN
)
528 rtx note
= find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
);
529 int region
= (note
? INTVAL (XEXP (note
, 0)) : 1);
531 call_had_abnormal_edge
= 0;
533 /* If there is an EH region or rethrow, we have an edge. */
534 if ((eh_region
&& region
> 0)
535 || find_reg_note (insn
, REG_EH_RETHROW
, NULL_RTX
))
536 call_had_abnormal_edge
= 1;
537 else if (nonlocal_goto_handler_labels
&& region
>= 0)
538 /* If there is a nonlocal goto label and the specified
539 region number isn't -1, we have an edge. (0 means
540 no throw, but might have a nonlocal goto). */
541 call_had_abnormal_edge
= 1;
546 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_BEG
)
548 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_END
)
552 /* The rest of the compiler works a bit smoother when we don't have to
553 check for the edge case of do-nothing functions with no basic blocks. */
556 emit_insn (gen_rtx_USE (VOIDmode
, const0_rtx
));
563 /* Scan a list of insns for labels referred to other than by jumps.
564 This is used to scan the alternatives of a call placeholder. */
566 find_label_refs (f
, lvl
)
572 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
577 /* Make a list of all labels referred to other than by jumps
578 (which just don't have the REG_LABEL notes).
580 Make a special exception for labels followed by an ADDR*VEC,
581 as this would be a part of the tablejump setup code.
583 Make a special exception for the eh_return_stub_label, which
584 we know isn't part of any otherwise visible control flow. */
586 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
587 if (REG_NOTE_KIND (note
) == REG_LABEL
)
589 rtx lab
= XEXP (note
, 0), next
;
591 if (lab
== eh_return_stub_label
)
593 else if ((next
= next_nonnote_insn (lab
)) != NULL
594 && GET_CODE (next
) == JUMP_INSN
595 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
596 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
598 else if (GET_CODE (lab
) == NOTE
)
601 lvl
= alloc_EXPR_LIST (0, XEXP (note
, 0), lvl
);
608 /* Find all basic blocks of the function whose first insn is F.
610 Collect and return a list of labels whose addresses are taken. This
611 will be used in make_edges for use with computed gotos. */
614 find_basic_blocks_1 (f
)
617 register rtx insn
, next
;
619 rtx bb_note
= NULL_RTX
;
620 rtx eh_list
= NULL_RTX
;
626 /* We process the instructions in a slightly different way than we did
627 previously. This is so that we see a NOTE_BASIC_BLOCK after we have
628 closed out the previous block, so that it gets attached at the proper
629 place. Since this form should be equivalent to the previous,
630 count_basic_blocks continues to use the old form as a check. */
632 for (insn
= f
; insn
; insn
= next
)
634 enum rtx_code code
= GET_CODE (insn
);
636 next
= NEXT_INSN (insn
);
642 int kind
= NOTE_LINE_NUMBER (insn
);
644 /* Keep a LIFO list of the currently active exception notes. */
645 if (kind
== NOTE_INSN_EH_REGION_BEG
)
646 eh_list
= alloc_INSN_LIST (insn
, eh_list
);
647 else if (kind
== NOTE_INSN_EH_REGION_END
)
651 eh_list
= XEXP (eh_list
, 1);
652 free_INSN_LIST_node (t
);
655 /* Look for basic block notes with which to keep the
656 basic_block_info pointers stable. Unthread the note now;
657 we'll put it back at the right place in create_basic_block.
658 Or not at all if we've already found a note in this block. */
659 else if (kind
== NOTE_INSN_BASIC_BLOCK
)
661 if (bb_note
== NULL_RTX
)
664 next
= flow_delete_insn (insn
);
670 /* A basic block starts at a label. If we've closed one off due
671 to a barrier or some such, no need to do it again. */
672 if (head
!= NULL_RTX
)
674 /* While we now have edge lists with which other portions of
675 the compiler might determine a call ending a basic block
676 does not imply an abnormal edge, it will be a bit before
677 everything can be updated. So continue to emit a noop at
678 the end of such a block. */
679 if (GET_CODE (end
) == CALL_INSN
&& ! SIBLING_CALL_P (end
))
681 rtx nop
= gen_rtx_USE (VOIDmode
, const0_rtx
);
682 end
= emit_insn_after (nop
, end
);
685 create_basic_block (i
++, head
, end
, bb_note
);
693 /* A basic block ends at a jump. */
694 if (head
== NULL_RTX
)
698 /* ??? Make a special check for table jumps. The way this
699 happens is truly and amazingly gross. We are about to
700 create a basic block that contains just a code label and
701 an addr*vec jump insn. Worse, an addr_diff_vec creates
702 its own natural loop.
704 Prevent this bit of brain damage, pasting things together
705 correctly in make_edges.
707 The correct solution involves emitting the table directly
708 on the tablejump instruction as a note, or JUMP_LABEL. */
710 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
711 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
719 goto new_bb_inclusive
;
722 /* A basic block ends at a barrier. It may be that an unconditional
723 jump already closed the basic block -- no need to do it again. */
724 if (head
== NULL_RTX
)
727 /* While we now have edge lists with which other portions of the
728 compiler might determine a call ending a basic block does not
729 imply an abnormal edge, it will be a bit before everything can
730 be updated. So continue to emit a noop at the end of such a
732 if (GET_CODE (end
) == CALL_INSN
&& ! SIBLING_CALL_P (end
))
734 rtx nop
= gen_rtx_USE (VOIDmode
, const0_rtx
);
735 end
= emit_insn_after (nop
, end
);
737 goto new_bb_exclusive
;
741 /* Record whether this call created an edge. */
742 rtx note
= find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
);
743 int region
= (note
? INTVAL (XEXP (note
, 0)) : 1);
744 int call_has_abnormal_edge
= 0;
746 if (GET_CODE (PATTERN (insn
)) == CALL_PLACEHOLDER
)
748 /* Scan each of the alternatives for label refs. */
749 lvl
= find_label_refs (XEXP (PATTERN (insn
), 0), lvl
);
750 lvl
= find_label_refs (XEXP (PATTERN (insn
), 1), lvl
);
751 lvl
= find_label_refs (XEXP (PATTERN (insn
), 2), lvl
);
752 /* Record its tail recursion label, if any. */
753 if (XEXP (PATTERN (insn
), 3) != NULL_RTX
)
754 trll
= alloc_EXPR_LIST (0, XEXP (PATTERN (insn
), 3), trll
);
757 /* If there is an EH region or rethrow, we have an edge. */
758 if ((eh_list
&& region
> 0)
759 || find_reg_note (insn
, REG_EH_RETHROW
, NULL_RTX
))
760 call_has_abnormal_edge
= 1;
761 else if (nonlocal_goto_handler_labels
&& region
>= 0)
762 /* If there is a nonlocal goto label and the specified
763 region number isn't -1, we have an edge. (0 means
764 no throw, but might have a nonlocal goto). */
765 call_has_abnormal_edge
= 1;
767 /* A basic block ends at a call that can either throw or
768 do a non-local goto. */
769 if (call_has_abnormal_edge
)
772 if (head
== NULL_RTX
)
777 create_basic_block (i
++, head
, end
, bb_note
);
778 head
= end
= NULL_RTX
;
786 if (GET_RTX_CLASS (code
) == 'i')
788 if (head
== NULL_RTX
)
795 if (GET_RTX_CLASS (code
) == 'i')
799 /* Make a list of all labels referred to other than by jumps
800 (which just don't have the REG_LABEL notes).
802 Make a special exception for labels followed by an ADDR*VEC,
803 as this would be a part of the tablejump setup code.
805 Make a special exception for the eh_return_stub_label, which
806 we know isn't part of any otherwise visible control flow. */
808 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
809 if (REG_NOTE_KIND (note
) == REG_LABEL
)
811 rtx lab
= XEXP (note
, 0), next
;
813 if (lab
== eh_return_stub_label
)
815 else if ((next
= next_nonnote_insn (lab
)) != NULL
816 && GET_CODE (next
) == JUMP_INSN
817 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
818 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
820 else if (GET_CODE (lab
) == NOTE
)
823 lvl
= alloc_EXPR_LIST (0, XEXP (note
, 0), lvl
);
828 if (head
!= NULL_RTX
)
829 create_basic_block (i
++, head
, end
, bb_note
);
831 flow_delete_insn (bb_note
);
833 if (i
!= n_basic_blocks
)
836 label_value_list
= lvl
;
837 tail_recursion_label_list
= trll
;
840 /* Tidy the CFG by deleting unreachable code and whatnot. */
846 delete_unreachable_blocks ();
847 move_stray_eh_region_notes ();
848 record_active_eh_regions (f
);
850 mark_critical_edges ();
852 /* Kill the data we won't maintain. */
853 free_EXPR_LIST_list (&label_value_list
);
854 free_EXPR_LIST_list (&tail_recursion_label_list
);
857 /* Create a new basic block consisting of the instructions between
858 HEAD and END inclusive. Reuses the note and basic block struct
859 in BB_NOTE, if any. */
862 create_basic_block (index
, head
, end
, bb_note
)
864 rtx head
, end
, bb_note
;
869 && ! RTX_INTEGRATED_P (bb_note
)
870 && (bb
= NOTE_BASIC_BLOCK (bb_note
)) != NULL
873 /* If we found an existing note, thread it back onto the chain. */
877 if (GET_CODE (head
) == CODE_LABEL
)
881 after
= PREV_INSN (head
);
885 if (after
!= bb_note
&& NEXT_INSN (after
) != bb_note
)
886 reorder_insns (bb_note
, bb_note
, after
);
890 /* Otherwise we must create a note and a basic block structure.
891 Since we allow basic block structs in rtl, give the struct
892 the same lifetime by allocating it off the function obstack
893 rather than using malloc. */
895 bb
= (basic_block
) obstack_alloc (function_obstack
, sizeof (*bb
));
896 memset (bb
, 0, sizeof (*bb
));
898 if (GET_CODE (head
) == CODE_LABEL
)
899 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, head
);
902 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, head
);
905 NOTE_BASIC_BLOCK (bb_note
) = bb
;
908 /* Always include the bb note in the block. */
909 if (NEXT_INSN (end
) == bb_note
)
915 BASIC_BLOCK (index
) = bb
;
917 /* Tag the block so that we know it has been used when considering
918 other basic block notes. */
922 /* Records the basic block struct in BB_FOR_INSN, for every instruction
923 indexed by INSN_UID. MAX is the size of the array. */
926 compute_bb_for_insn (max
)
931 if (basic_block_for_insn
)
932 VARRAY_FREE (basic_block_for_insn
);
933 VARRAY_BB_INIT (basic_block_for_insn
, max
, "basic_block_for_insn");
935 for (i
= 0; i
< n_basic_blocks
; ++i
)
937 basic_block bb
= BASIC_BLOCK (i
);
944 int uid
= INSN_UID (insn
);
946 VARRAY_BB (basic_block_for_insn
, uid
) = bb
;
949 insn
= NEXT_INSN (insn
);
954 /* Free the memory associated with the edge structures. */
962 for (i
= 0; i
< n_basic_blocks
; ++i
)
964 basic_block bb
= BASIC_BLOCK (i
);
966 for (e
= bb
->succ
; e
; e
= n
)
976 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= n
)
982 ENTRY_BLOCK_PTR
->succ
= 0;
983 EXIT_BLOCK_PTR
->pred
= 0;
988 /* Identify the edges between basic blocks.
990 NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
991 that are otherwise unreachable may be reachable with a non-local goto.
993 BB_EH_END is an array indexed by basic block number in which we record
994 the list of exception regions active at the end of the basic block. */
997 make_edges (label_value_list
)
998 rtx label_value_list
;
1001 eh_nesting_info
*eh_nest_info
= init_eh_nesting_info ();
1002 sbitmap
*edge_cache
= NULL
;
1004 /* Assume no computed jump; revise as we create edges. */
1005 current_function_has_computed_jump
= 0;
1007 /* Heavy use of computed goto in machine-generated code can lead to
1008 nearly fully-connected CFGs. In that case we spend a significant
1009 amount of time searching the edge lists for duplicates. */
1010 if (forced_labels
|| label_value_list
)
1012 edge_cache
= sbitmap_vector_alloc (n_basic_blocks
, n_basic_blocks
);
1013 sbitmap_vector_zero (edge_cache
, n_basic_blocks
);
1016 /* By nature of the way these get numbered, block 0 is always the entry. */
1017 make_edge (edge_cache
, ENTRY_BLOCK_PTR
, BASIC_BLOCK (0), EDGE_FALLTHRU
);
1019 for (i
= 0; i
< n_basic_blocks
; ++i
)
1021 basic_block bb
= BASIC_BLOCK (i
);
1024 int force_fallthru
= 0;
1026 /* Examine the last instruction of the block, and discover the
1027 ways we can leave the block. */
1030 code
= GET_CODE (insn
);
1033 if (code
== JUMP_INSN
)
1037 /* ??? Recognize a tablejump and do the right thing. */
1038 if ((tmp
= JUMP_LABEL (insn
)) != NULL_RTX
1039 && (tmp
= NEXT_INSN (tmp
)) != NULL_RTX
1040 && GET_CODE (tmp
) == JUMP_INSN
1041 && (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
1042 || GET_CODE (PATTERN (tmp
)) == ADDR_DIFF_VEC
))
1047 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
1048 vec
= XVEC (PATTERN (tmp
), 0);
1050 vec
= XVEC (PATTERN (tmp
), 1);
1052 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
1053 make_label_edge (edge_cache
, bb
,
1054 XEXP (RTVEC_ELT (vec
, j
), 0), 0);
1056 /* Some targets (eg, ARM) emit a conditional jump that also
1057 contains the out-of-range target. Scan for these and
1058 add an edge if necessary. */
1059 if ((tmp
= single_set (insn
)) != NULL
1060 && SET_DEST (tmp
) == pc_rtx
1061 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
1062 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
)
1063 make_label_edge (edge_cache
, bb
,
1064 XEXP (XEXP (SET_SRC (tmp
), 2), 0), 0);
1066 #ifdef CASE_DROPS_THROUGH
1067 /* Silly VAXen. The ADDR_VEC is going to be in the way of
1068 us naturally detecting fallthru into the next block. */
1073 /* If this is a computed jump, then mark it as reaching
1074 everything on the label_value_list and forced_labels list. */
1075 else if (computed_jump_p (insn
))
1077 current_function_has_computed_jump
= 1;
1079 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
1080 make_label_edge (edge_cache
, bb
, XEXP (x
, 0), EDGE_ABNORMAL
);
1082 for (x
= forced_labels
; x
; x
= XEXP (x
, 1))
1083 make_label_edge (edge_cache
, bb
, XEXP (x
, 0), EDGE_ABNORMAL
);
1086 /* Returns create an exit out. */
1087 else if (returnjump_p (insn
))
1088 make_edge (edge_cache
, bb
, EXIT_BLOCK_PTR
, 0);
1090 /* Otherwise, we have a plain conditional or unconditional jump. */
1093 if (! JUMP_LABEL (insn
))
1095 make_label_edge (edge_cache
, bb
, JUMP_LABEL (insn
), 0);
1099 /* If this is a sibling call insn, then this is in effect a
1100 combined call and return, and so we need an edge to the
1101 exit block. No need to worry about EH edges, since we
1102 wouldn't have created the sibling call in the first place. */
1104 if (code
== CALL_INSN
&& SIBLING_CALL_P (insn
))
1105 make_edge (edge_cache
, bb
, EXIT_BLOCK_PTR
,
1106 EDGE_ABNORMAL
| EDGE_ABNORMAL_CALL
);
1109 /* If this is a CALL_INSN, then mark it as reaching the active EH
1110 handler for this CALL_INSN. If we're handling asynchronous
1111 exceptions then any insn can reach any of the active handlers.
1113 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
1115 if (code
== CALL_INSN
|| asynchronous_exceptions
)
1117 /* Add any appropriate EH edges. We do this unconditionally
1118 since there may be a REG_EH_REGION or REG_EH_RETHROW note
1119 on the call, and this needn't be within an EH region. */
1120 make_eh_edge (edge_cache
, eh_nest_info
, bb
, insn
, bb
->eh_end
);
1122 /* If we have asynchronous exceptions, do the same for *all*
1123 exception regions active in the block. */
1124 if (asynchronous_exceptions
1125 && bb
->eh_beg
!= bb
->eh_end
)
1127 if (bb
->eh_beg
>= 0)
1128 make_eh_edge (edge_cache
, eh_nest_info
, bb
,
1129 NULL_RTX
, bb
->eh_beg
);
1131 for (x
= bb
->head
; x
!= bb
->end
; x
= NEXT_INSN (x
))
1132 if (GET_CODE (x
) == NOTE
1133 && (NOTE_LINE_NUMBER (x
) == NOTE_INSN_EH_REGION_BEG
1134 || NOTE_LINE_NUMBER (x
) == NOTE_INSN_EH_REGION_END
))
1136 int region
= NOTE_EH_HANDLER (x
);
1137 make_eh_edge (edge_cache
, eh_nest_info
, bb
,
1142 if (code
== CALL_INSN
&& nonlocal_goto_handler_labels
)
1144 /* ??? This could be made smarter: in some cases it's possible
1145 to tell that certain calls will not do a nonlocal goto.
1147 For example, if the nested functions that do the nonlocal
1148 gotos do not have their addresses taken, then only calls to
1149 those functions or to other nested functions that use them
1150 could possibly do nonlocal gotos. */
1151 /* We do know that a REG_EH_REGION note with a value less
1152 than 0 is guaranteed not to perform a non-local goto. */
1153 rtx note
= find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
);
1154 if (!note
|| INTVAL (XEXP (note
, 0)) >= 0)
1155 for (x
= nonlocal_goto_handler_labels
; x
; x
= XEXP (x
, 1))
1156 make_label_edge (edge_cache
, bb
, XEXP (x
, 0),
1157 EDGE_ABNORMAL
| EDGE_ABNORMAL_CALL
);
1161 /* We know something about the structure of the function __throw in
1162 libgcc2.c. It is the only function that ever contains eh_stub
1163 labels. It modifies its return address so that the last block
1164 returns to one of the eh_stub labels within it. So we have to
1165 make additional edges in the flow graph. */
1166 if (i
+ 1 == n_basic_blocks
&& eh_return_stub_label
!= 0)
1167 make_label_edge (edge_cache
, bb
, eh_return_stub_label
, EDGE_EH
);
1169 /* Find out if we can drop through to the next block. */
1170 insn
= next_nonnote_insn (insn
);
1171 if (!insn
|| (i
+ 1 == n_basic_blocks
&& force_fallthru
))
1172 make_edge (edge_cache
, bb
, EXIT_BLOCK_PTR
, EDGE_FALLTHRU
);
1173 else if (i
+ 1 < n_basic_blocks
)
1175 rtx tmp
= BLOCK_HEAD (i
+ 1);
1176 if (GET_CODE (tmp
) == NOTE
)
1177 tmp
= next_nonnote_insn (tmp
);
1178 if (force_fallthru
|| insn
== tmp
)
1179 make_edge (edge_cache
, bb
, BASIC_BLOCK (i
+ 1), EDGE_FALLTHRU
);
1183 free_eh_nesting_info (eh_nest_info
);
1185 sbitmap_vector_free (edge_cache
);
1188 /* Create an edge between two basic blocks. FLAGS are auxiliary information
1189 about the edge that is accumulated between calls. */
1192 make_edge (edge_cache
, src
, dst
, flags
)
1193 sbitmap
*edge_cache
;
1194 basic_block src
, dst
;
1200 /* Don't bother with edge cache for ENTRY or EXIT; there aren't that
1201 many edges to them, and we didn't allocate memory for it. */
1202 use_edge_cache
= (edge_cache
1203 && src
!= ENTRY_BLOCK_PTR
1204 && dst
!= EXIT_BLOCK_PTR
);
1206 /* Make sure we don't add duplicate edges. */
1207 if (! use_edge_cache
|| TEST_BIT (edge_cache
[src
->index
], dst
->index
))
1208 for (e
= src
->succ
; e
; e
= e
->succ_next
)
1215 e
= (edge
) xcalloc (1, sizeof (*e
));
1218 e
->succ_next
= src
->succ
;
1219 e
->pred_next
= dst
->pred
;
1228 SET_BIT (edge_cache
[src
->index
], dst
->index
);
1231 /* Create an edge from a basic block to a label. */
1234 make_label_edge (edge_cache
, src
, label
, flags
)
1235 sbitmap
*edge_cache
;
1240 if (GET_CODE (label
) != CODE_LABEL
)
1243 /* If the label was never emitted, this insn is junk, but avoid a
1244 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
1245 as a result of a syntax error and a diagnostic has already been
1248 if (INSN_UID (label
) == 0)
1251 make_edge (edge_cache
, src
, BLOCK_FOR_INSN (label
), flags
);
1254 /* Create the edges generated by INSN in REGION. */
1257 make_eh_edge (edge_cache
, eh_nest_info
, src
, insn
, region
)
1258 sbitmap
*edge_cache
;
1259 eh_nesting_info
*eh_nest_info
;
1264 handler_info
**handler_list
;
1267 is_call
= (insn
&& GET_CODE (insn
) == CALL_INSN
? EDGE_ABNORMAL_CALL
: 0);
1268 num
= reachable_handlers (region
, eh_nest_info
, insn
, &handler_list
);
1271 make_label_edge (edge_cache
, src
, handler_list
[num
]->handler_label
,
1272 EDGE_ABNORMAL
| EDGE_EH
| is_call
);
1276 /* EH_REGION notes appearing between basic blocks is ambiguous, and even
1277 dangerous if we intend to move basic blocks around. Move such notes
1278 into the following block. */
1281 move_stray_eh_region_notes ()
1286 if (n_basic_blocks
< 2)
1289 b2
= BASIC_BLOCK (n_basic_blocks
- 1);
1290 for (i
= n_basic_blocks
- 2; i
>= 0; --i
, b2
= b1
)
1292 rtx insn
, next
, list
= NULL_RTX
;
1294 b1
= BASIC_BLOCK (i
);
1295 for (insn
= NEXT_INSN (b1
->end
); insn
!= b2
->head
; insn
= next
)
1297 next
= NEXT_INSN (insn
);
1298 if (GET_CODE (insn
) == NOTE
1299 && (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_BEG
1300 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_END
))
1302 /* Unlink from the insn chain. */
1303 NEXT_INSN (PREV_INSN (insn
)) = next
;
1304 PREV_INSN (next
) = PREV_INSN (insn
);
1307 NEXT_INSN (insn
) = list
;
1312 if (list
== NULL_RTX
)
1315 /* Find where to insert these things. */
1317 if (GET_CODE (insn
) == CODE_LABEL
)
1318 insn
= NEXT_INSN (insn
);
1322 next
= NEXT_INSN (list
);
1323 add_insn_after (list
, insn
);
1329 /* Recompute eh_beg/eh_end for each basic block. */
1332 record_active_eh_regions (f
)
1335 rtx insn
, eh_list
= NULL_RTX
;
1337 basic_block bb
= BASIC_BLOCK (0);
1339 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
1341 if (bb
->head
== insn
)
1342 bb
->eh_beg
= (eh_list
? NOTE_EH_HANDLER (XEXP (eh_list
, 0)) : -1);
1344 if (GET_CODE (insn
) == NOTE
)
1346 int kind
= NOTE_LINE_NUMBER (insn
);
1347 if (kind
== NOTE_INSN_EH_REGION_BEG
)
1348 eh_list
= alloc_INSN_LIST (insn
, eh_list
);
1349 else if (kind
== NOTE_INSN_EH_REGION_END
)
1351 rtx t
= XEXP (eh_list
, 1);
1352 free_INSN_LIST_node (eh_list
);
1357 if (bb
->end
== insn
)
1359 bb
->eh_end
= (eh_list
? NOTE_EH_HANDLER (XEXP (eh_list
, 0)) : -1);
1361 if (i
== n_basic_blocks
)
1363 bb
= BASIC_BLOCK (i
);
1368 /* Identify critical edges and set the bits appropriately. */
1371 mark_critical_edges ()
1373 int i
, n
= n_basic_blocks
;
1376 /* We begin with the entry block. This is not terribly important now,
1377 but could be if a front end (Fortran) implemented alternate entry
1379 bb
= ENTRY_BLOCK_PTR
;
1386 /* (1) Critical edges must have a source with multiple successors. */
1387 if (bb
->succ
&& bb
->succ
->succ_next
)
1389 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1391 /* (2) Critical edges must have a destination with multiple
1392 predecessors. Note that we know there is at least one
1393 predecessor -- the edge we followed to get here. */
1394 if (e
->dest
->pred
->pred_next
)
1395 e
->flags
|= EDGE_CRITICAL
;
1397 e
->flags
&= ~EDGE_CRITICAL
;
1402 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1403 e
->flags
&= ~EDGE_CRITICAL
;
1408 bb
= BASIC_BLOCK (i
);
1412 /* Split a (typically critical) edge. Return the new block.
1413 Abort on abnormal edges.
1415 ??? The code generally expects to be called on critical edges.
1416 The case of a block ending in an unconditional jump to a
1417 block with multiple predecessors is not handled optimally. */
1420 split_edge (edge_in
)
1423 basic_block old_pred
, bb
, old_succ
;
1428 /* Abnormal edges cannot be split. */
1429 if ((edge_in
->flags
& EDGE_ABNORMAL
) != 0)
1432 old_pred
= edge_in
->src
;
1433 old_succ
= edge_in
->dest
;
1435 /* Remove the existing edge from the destination's pred list. */
1438 for (pp
= &old_succ
->pred
; *pp
!= edge_in
; pp
= &(*pp
)->pred_next
)
1440 *pp
= edge_in
->pred_next
;
1441 edge_in
->pred_next
= NULL
;
1444 /* Create the new structures. */
1445 bb
= (basic_block
) obstack_alloc (function_obstack
, sizeof (*bb
));
1446 edge_out
= (edge
) xcalloc (1, sizeof (*edge_out
));
1449 memset (bb
, 0, sizeof (*bb
));
1451 /* ??? This info is likely going to be out of date very soon. */
1452 if (old_succ
->global_live_at_start
)
1454 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (function_obstack
);
1455 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (function_obstack
);
1456 COPY_REG_SET (bb
->global_live_at_start
, old_succ
->global_live_at_start
);
1457 COPY_REG_SET (bb
->global_live_at_end
, old_succ
->global_live_at_start
);
1462 bb
->succ
= edge_out
;
1463 bb
->count
= edge_in
->count
;
1466 edge_in
->flags
&= ~EDGE_CRITICAL
;
1468 edge_out
->pred_next
= old_succ
->pred
;
1469 edge_out
->succ_next
= NULL
;
1471 edge_out
->dest
= old_succ
;
1472 edge_out
->flags
= EDGE_FALLTHRU
;
1473 edge_out
->probability
= REG_BR_PROB_BASE
;
1474 edge_out
->count
= edge_in
->count
;
1476 old_succ
->pred
= edge_out
;
1478 /* Tricky case -- if there existed a fallthru into the successor
1479 (and we're not it) we must add a new unconditional jump around
1480 the new block we're actually interested in.
1482 Further, if that edge is critical, this means a second new basic
1483 block must be created to hold it. In order to simplify correct
1484 insn placement, do this before we touch the existing basic block
1485 ordering for the block we were really wanting. */
1486 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1489 for (e
= edge_out
->pred_next
; e
; e
= e
->pred_next
)
1490 if (e
->flags
& EDGE_FALLTHRU
)
1495 basic_block jump_block
;
1498 if ((e
->flags
& EDGE_CRITICAL
) == 0
1499 && e
->src
!= ENTRY_BLOCK_PTR
)
1501 /* Non critical -- we can simply add a jump to the end
1502 of the existing predecessor. */
1503 jump_block
= e
->src
;
1507 /* We need a new block to hold the jump. The simplest
1508 way to do the bulk of the work here is to recursively
1510 jump_block
= split_edge (e
);
1511 e
= jump_block
->succ
;
1514 /* Now add the jump insn ... */
1515 pos
= emit_jump_insn_after (gen_jump (old_succ
->head
),
1517 jump_block
->end
= pos
;
1518 if (basic_block_for_insn
)
1519 set_block_for_insn (pos
, jump_block
);
1520 emit_barrier_after (pos
);
1522 /* ... let jump know that label is in use, ... */
1523 JUMP_LABEL (pos
) = old_succ
->head
;
1524 ++LABEL_NUSES (old_succ
->head
);
1526 /* ... and clear fallthru on the outgoing edge. */
1527 e
->flags
&= ~EDGE_FALLTHRU
;
1529 /* Continue splitting the interesting edge. */
1533 /* Place the new block just in front of the successor. */
1534 VARRAY_GROW (basic_block_info
, ++n_basic_blocks
);
1535 if (old_succ
== EXIT_BLOCK_PTR
)
1536 j
= n_basic_blocks
- 1;
1538 j
= old_succ
->index
;
1539 for (i
= n_basic_blocks
- 1; i
> j
; --i
)
1541 basic_block tmp
= BASIC_BLOCK (i
- 1);
1542 BASIC_BLOCK (i
) = tmp
;
1545 BASIC_BLOCK (i
) = bb
;
1548 /* Create the basic block note.
1550 Where we place the note can have a noticable impact on the generated
1551 code. Consider this cfg:
1562 If we need to insert an insn on the edge from block 0 to block 1,
1563 we want to ensure the instructions we insert are outside of any
1564 loop notes that physically sit between block 0 and block 1. Otherwise
1565 we confuse the loop optimizer into thinking the loop is a phony. */
1566 if (old_succ
!= EXIT_BLOCK_PTR
1567 && PREV_INSN (old_succ
->head
)
1568 && GET_CODE (PREV_INSN (old_succ
->head
)) == NOTE
1569 && NOTE_LINE_NUMBER (PREV_INSN (old_succ
->head
)) == NOTE_INSN_LOOP_BEG
)
1570 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
,
1571 PREV_INSN (old_succ
->head
));
1572 else if (old_succ
!= EXIT_BLOCK_PTR
)
1573 bb_note
= emit_note_before (NOTE_INSN_BASIC_BLOCK
, old_succ
->head
);
1575 bb_note
= emit_note_after (NOTE_INSN_BASIC_BLOCK
, get_last_insn ());
1576 NOTE_BASIC_BLOCK (bb_note
) = bb
;
1577 bb
->head
= bb
->end
= bb_note
;
1579 /* Not quite simple -- for non-fallthru edges, we must adjust the
1580 predecessor's jump instruction to target our new block. */
1581 if ((edge_in
->flags
& EDGE_FALLTHRU
) == 0)
1583 rtx tmp
, insn
= old_pred
->end
;
1584 rtx old_label
= old_succ
->head
;
1585 rtx new_label
= gen_label_rtx ();
1587 if (GET_CODE (insn
) != JUMP_INSN
)
1590 /* ??? Recognize a tablejump and adjust all matching cases. */
1591 if ((tmp
= JUMP_LABEL (insn
)) != NULL_RTX
1592 && (tmp
= NEXT_INSN (tmp
)) != NULL_RTX
1593 && GET_CODE (tmp
) == JUMP_INSN
1594 && (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
1595 || GET_CODE (PATTERN (tmp
)) == ADDR_DIFF_VEC
))
1600 if (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
)
1601 vec
= XVEC (PATTERN (tmp
), 0);
1603 vec
= XVEC (PATTERN (tmp
), 1);
1605 for (j
= GET_NUM_ELEM (vec
) - 1; j
>= 0; --j
)
1606 if (XEXP (RTVEC_ELT (vec
, j
), 0) == old_label
)
1608 RTVEC_ELT (vec
, j
) = gen_rtx_LABEL_REF (VOIDmode
, new_label
);
1609 --LABEL_NUSES (old_label
);
1610 ++LABEL_NUSES (new_label
);
1613 /* Handle casesi dispatch insns */
1614 if ((tmp
= single_set (insn
)) != NULL
1615 && SET_DEST (tmp
) == pc_rtx
1616 && GET_CODE (SET_SRC (tmp
)) == IF_THEN_ELSE
1617 && GET_CODE (XEXP (SET_SRC (tmp
), 2)) == LABEL_REF
1618 && XEXP (XEXP (SET_SRC (tmp
), 2), 0) == old_label
)
1620 XEXP (SET_SRC (tmp
), 2) = gen_rtx_LABEL_REF (VOIDmode
,
1622 --LABEL_NUSES (old_label
);
1623 ++LABEL_NUSES (new_label
);
1628 /* This would have indicated an abnormal edge. */
1629 if (computed_jump_p (insn
))
1632 /* A return instruction can't be redirected. */
1633 if (returnjump_p (insn
))
1636 /* If the insn doesn't go where we think, we're confused. */
1637 if (JUMP_LABEL (insn
) != old_label
)
1640 redirect_jump (insn
, new_label
, 0);
1643 emit_label_before (new_label
, bb_note
);
1644 bb
->head
= new_label
;
1650 /* Queue instructions for insertion on an edge between two basic blocks.
1651 The new instructions and basic blocks (if any) will not appear in the
1652 CFG until commit_edge_insertions is called. */
1655 insert_insn_on_edge (pattern
, e
)
1659 /* We cannot insert instructions on an abnormal critical edge.
1660 It will be easier to find the culprit if we die now. */
1661 if ((e
->flags
& (EDGE_ABNORMAL
|EDGE_CRITICAL
))
1662 == (EDGE_ABNORMAL
|EDGE_CRITICAL
))
1665 if (e
->insns
== NULL_RTX
)
1668 push_to_sequence (e
->insns
);
1670 emit_insn (pattern
);
1672 e
->insns
= get_insns ();
1676 /* Update the CFG for the instructions queued on edge E. */
1679 commit_one_edge_insertion (e
)
1682 rtx before
= NULL_RTX
, after
= NULL_RTX
, insns
, tmp
, last
;
1685 /* Pull the insns off the edge now since the edge might go away. */
1687 e
->insns
= NULL_RTX
;
1689 /* Figure out where to put these things. If the destination has
1690 one predecessor, insert there. Except for the exit block. */
1691 if (e
->dest
->pred
->pred_next
== NULL
1692 && e
->dest
!= EXIT_BLOCK_PTR
)
1696 /* Get the location correct wrt a code label, and "nice" wrt
1697 a basic block note, and before everything else. */
1699 if (GET_CODE (tmp
) == CODE_LABEL
)
1700 tmp
= NEXT_INSN (tmp
);
1701 if (NOTE_INSN_BASIC_BLOCK_P (tmp
))
1702 tmp
= NEXT_INSN (tmp
);
1703 if (tmp
== bb
->head
)
1706 after
= PREV_INSN (tmp
);
1709 /* If the source has one successor and the edge is not abnormal,
1710 insert there. Except for the entry block. */
1711 else if ((e
->flags
& EDGE_ABNORMAL
) == 0
1712 && e
->src
->succ
->succ_next
== NULL
1713 && e
->src
!= ENTRY_BLOCK_PTR
)
1716 /* It is possible to have a non-simple jump here. Consider a target
1717 where some forms of unconditional jumps clobber a register. This
1718 happens on the fr30 for example.
1720 We know this block has a single successor, so we can just emit
1721 the queued insns before the jump. */
1722 if (GET_CODE (bb
->end
) == JUMP_INSN
)
1728 /* We'd better be fallthru, or we've lost track of what's what. */
1729 if ((e
->flags
& EDGE_FALLTHRU
) == 0)
1736 /* Otherwise we must split the edge. */
1739 bb
= split_edge (e
);
1743 /* Now that we've found the spot, do the insertion. */
1745 /* Set the new block number for these insns, if structure is allocated. */
1746 if (basic_block_for_insn
)
1749 for (i
= insns
; i
!= NULL_RTX
; i
= NEXT_INSN (i
))
1750 set_block_for_insn (i
, bb
);
1755 emit_insns_before (insns
, before
);
1756 if (before
== bb
->head
)
1759 last
= prev_nonnote_insn (before
);
1763 last
= emit_insns_after (insns
, after
);
1764 if (after
== bb
->end
)
1768 if (returnjump_p (last
))
1770 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1771 This is not currently a problem because this only happens
1772 for the (single) epilogue, which already has a fallthru edge
1776 if (e
->dest
!= EXIT_BLOCK_PTR
1777 || e
->succ_next
!= NULL
1778 || (e
->flags
& EDGE_FALLTHRU
) == 0)
1780 e
->flags
&= ~EDGE_FALLTHRU
;
1782 emit_barrier_after (last
);
1786 flow_delete_insn (before
);
1788 else if (GET_CODE (last
) == JUMP_INSN
)
1792 /* Update the CFG for all queued instructions. */
1795 commit_edge_insertions ()
1800 #ifdef ENABLE_CHECKING
1801 verify_flow_info ();
1805 bb
= ENTRY_BLOCK_PTR
;
1810 for (e
= bb
->succ
; e
; e
= next
)
1812 next
= e
->succ_next
;
1814 commit_one_edge_insertion (e
);
1817 if (++i
>= n_basic_blocks
)
1819 bb
= BASIC_BLOCK (i
);
1823 /* Delete all unreachable basic blocks. */
1826 delete_unreachable_blocks ()
1828 basic_block
*worklist
, *tos
;
1829 int deleted_handler
;
1834 tos
= worklist
= (basic_block
*) xmalloc (sizeof (basic_block
) * n
);
1836 /* Use basic_block->aux as a marker. Clear them all. */
1838 for (i
= 0; i
< n
; ++i
)
1839 BASIC_BLOCK (i
)->aux
= NULL
;
1841 /* Add our starting points to the worklist. Almost always there will
1842 be only one. It isn't inconcievable that we might one day directly
1843 support Fortran alternate entry points. */
1845 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
1849 /* Mark the block with a handy non-null value. */
1853 /* Iterate: find everything reachable from what we've already seen. */
1855 while (tos
!= worklist
)
1857 basic_block b
= *--tos
;
1859 for (e
= b
->succ
; e
; e
= e
->succ_next
)
1867 /* Delete all unreachable basic blocks. Count down so that we don't
1868 interfere with the block renumbering that happens in flow_delete_block. */
1870 deleted_handler
= 0;
1872 for (i
= n
- 1; i
>= 0; --i
)
1874 basic_block b
= BASIC_BLOCK (i
);
1877 /* This block was found. Tidy up the mark. */
1880 deleted_handler
|= flow_delete_block (b
);
1883 tidy_fallthru_edges ();
1885 /* If we deleted an exception handler, we may have EH region begin/end
1886 blocks to remove as well. */
1887 if (deleted_handler
)
1888 delete_eh_regions ();
1893 /* Find EH regions for which there is no longer a handler, and delete them. */
1896 delete_eh_regions ()
1900 update_rethrow_references ();
1902 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
1903 if (GET_CODE (insn
) == NOTE
)
1905 if ((NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_BEG
) ||
1906 (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_END
))
1908 int num
= NOTE_EH_HANDLER (insn
);
1909 /* A NULL handler indicates a region is no longer needed,
1910 as long as its rethrow label isn't used. */
1911 if (get_first_handler (num
) == NULL
&& ! rethrow_used (num
))
1913 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
1914 NOTE_SOURCE_FILE (insn
) = 0;
1920 /* Return true if NOTE is not one of the ones that must be kept paired,
1921 so that we may simply delete them. */
1924 can_delete_note_p (note
)
1927 return (NOTE_LINE_NUMBER (note
) == NOTE_INSN_DELETED
1928 || NOTE_LINE_NUMBER (note
) == NOTE_INSN_BASIC_BLOCK
);
1931 /* Unlink a chain of insns between START and FINISH, leaving notes
1932 that must be paired. */
1935 flow_delete_insn_chain (start
, finish
)
1938 /* Unchain the insns one by one. It would be quicker to delete all
1939 of these with a single unchaining, rather than one at a time, but
1940 we need to keep the NOTE's. */
1946 next
= NEXT_INSN (start
);
1947 if (GET_CODE (start
) == NOTE
&& !can_delete_note_p (start
))
1949 else if (GET_CODE (start
) == CODE_LABEL
1950 && ! can_delete_label_p (start
))
1952 const char *name
= LABEL_NAME (start
);
1953 PUT_CODE (start
, NOTE
);
1954 NOTE_LINE_NUMBER (start
) = NOTE_INSN_DELETED_LABEL
;
1955 NOTE_SOURCE_FILE (start
) = name
;
1958 next
= flow_delete_insn (start
);
1960 if (start
== finish
)
1966 /* Delete the insns in a (non-live) block. We physically delete every
1967 non-deleted-note insn, and update the flow graph appropriately.
1969 Return nonzero if we deleted an exception handler. */
1971 /* ??? Preserving all such notes strikes me as wrong. It would be nice
1972 to post-process the stream to remove empty blocks, loops, ranges, etc. */
1975 flow_delete_block (b
)
1978 int deleted_handler
= 0;
1981 /* If the head of this block is a CODE_LABEL, then it might be the
1982 label for an exception handler which can't be reached.
1984 We need to remove the label from the exception_handler_label list
1985 and remove the associated NOTE_INSN_EH_REGION_BEG and
1986 NOTE_INSN_EH_REGION_END notes. */
1990 never_reached_warning (insn
);
1992 if (GET_CODE (insn
) == CODE_LABEL
)
1994 rtx x
, *prev
= &exception_handler_labels
;
1996 for (x
= exception_handler_labels
; x
; x
= XEXP (x
, 1))
1998 if (XEXP (x
, 0) == insn
)
2000 /* Found a match, splice this label out of the EH label list. */
2001 *prev
= XEXP (x
, 1);
2002 XEXP (x
, 1) = NULL_RTX
;
2003 XEXP (x
, 0) = NULL_RTX
;
2005 /* Remove the handler from all regions */
2006 remove_handler (insn
);
2007 deleted_handler
= 1;
2010 prev
= &XEXP (x
, 1);
2014 /* Include any jump table following the basic block. */
2016 if (GET_CODE (end
) == JUMP_INSN
2017 && (tmp
= JUMP_LABEL (end
)) != NULL_RTX
2018 && (tmp
= NEXT_INSN (tmp
)) != NULL_RTX
2019 && GET_CODE (tmp
) == JUMP_INSN
2020 && (GET_CODE (PATTERN (tmp
)) == ADDR_VEC
2021 || GET_CODE (PATTERN (tmp
)) == ADDR_DIFF_VEC
))
2024 /* Include any barrier that may follow the basic block. */
2025 tmp
= next_nonnote_insn (end
);
2026 if (tmp
&& GET_CODE (tmp
) == BARRIER
)
2029 /* Selectively delete the entire chain. */
2030 flow_delete_insn_chain (insn
, end
);
2032 /* Remove the edges into and out of this block. Note that there may
2033 indeed be edges in, if we are removing an unreachable loop. */
2037 for (e
= b
->pred
; e
; e
= next
)
2039 for (q
= &e
->src
->succ
; *q
!= e
; q
= &(*q
)->succ_next
)
2042 next
= e
->pred_next
;
2046 for (e
= b
->succ
; e
; e
= next
)
2048 for (q
= &e
->dest
->pred
; *q
!= e
; q
= &(*q
)->pred_next
)
2051 next
= e
->succ_next
;
2060 /* Remove the basic block from the array, and compact behind it. */
2063 return deleted_handler
;
2066 /* Remove block B from the basic block array and compact behind it. */
2072 int i
, n
= n_basic_blocks
;
2074 for (i
= b
->index
; i
+ 1 < n
; ++i
)
2076 basic_block x
= BASIC_BLOCK (i
+ 1);
2077 BASIC_BLOCK (i
) = x
;
2081 basic_block_info
->num_elements
--;
2085 /* Delete INSN by patching it out. Return the next insn. */
2088 flow_delete_insn (insn
)
2091 rtx prev
= PREV_INSN (insn
);
2092 rtx next
= NEXT_INSN (insn
);
2095 PREV_INSN (insn
) = NULL_RTX
;
2096 NEXT_INSN (insn
) = NULL_RTX
;
2097 INSN_DELETED_P (insn
) = 1;
2100 NEXT_INSN (prev
) = next
;
2102 PREV_INSN (next
) = prev
;
2104 set_last_insn (prev
);
2106 if (GET_CODE (insn
) == CODE_LABEL
)
2107 remove_node_from_expr_list (insn
, &nonlocal_goto_handler_labels
);
2109 /* If deleting a jump, decrement the use count of the label. Deleting
2110 the label itself should happen in the normal course of block merging. */
2111 if (GET_CODE (insn
) == JUMP_INSN
2112 && JUMP_LABEL (insn
)
2113 && GET_CODE (JUMP_LABEL (insn
)) == CODE_LABEL
)
2114 LABEL_NUSES (JUMP_LABEL (insn
))--;
2116 /* Also if deleting an insn that references a label. */
2117 else if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)) != NULL_RTX
2118 && GET_CODE (XEXP (note
, 0)) == CODE_LABEL
)
2119 LABEL_NUSES (XEXP (note
, 0))--;
2124 /* True if a given label can be deleted. */
2127 can_delete_label_p (label
)
2132 if (LABEL_PRESERVE_P (label
))
2135 for (x
= forced_labels
; x
; x
= XEXP (x
, 1))
2136 if (label
== XEXP (x
, 0))
2138 for (x
= label_value_list
; x
; x
= XEXP (x
, 1))
2139 if (label
== XEXP (x
, 0))
2141 for (x
= exception_handler_labels
; x
; x
= XEXP (x
, 1))
2142 if (label
== XEXP (x
, 0))
2145 /* User declared labels must be preserved. */
2146 if (LABEL_NAME (label
) != 0)
2153 tail_recursion_label_p (label
)
2158 for (x
= tail_recursion_label_list
; x
; x
= XEXP (x
, 1))
2159 if (label
== XEXP (x
, 0))
2165 /* Blocks A and B are to be merged into a single block A. The insns
2166 are already contiguous, hence `nomove'. */
2169 merge_blocks_nomove (a
, b
)
2173 rtx b_head
, b_end
, a_end
;
2174 rtx del_first
= NULL_RTX
, del_last
= NULL_RTX
;
2177 /* If there was a CODE_LABEL beginning B, delete it. */
2180 if (GET_CODE (b_head
) == CODE_LABEL
)
2182 /* Detect basic blocks with nothing but a label. This can happen
2183 in particular at the end of a function. */
2184 if (b_head
== b_end
)
2186 del_first
= del_last
= b_head
;
2187 b_head
= NEXT_INSN (b_head
);
2190 /* Delete the basic block note. */
2191 if (NOTE_INSN_BASIC_BLOCK_P (b_head
))
2193 if (b_head
== b_end
)
2198 b_head
= NEXT_INSN (b_head
);
2201 /* If there was a jump out of A, delete it. */
2203 if (GET_CODE (a_end
) == JUMP_INSN
)
2207 prev
= prev_nonnote_insn (a_end
);
2214 /* If this was a conditional jump, we need to also delete
2215 the insn that set cc0. */
2216 if (prev
&& sets_cc0_p (prev
))
2219 prev
= prev_nonnote_insn (prev
);
2228 else if (GET_CODE (NEXT_INSN (a_end
)) == BARRIER
)
2229 del_first
= NEXT_INSN (a_end
);
2231 /* Delete everything marked above as well as crap that might be
2232 hanging out between the two blocks. */
2233 flow_delete_insn_chain (del_first
, del_last
);
2235 /* Normally there should only be one successor of A and that is B, but
2236 partway though the merge of blocks for conditional_execution we'll
2237 be merging a TEST block with THEN and ELSE successors. Free the
2238 whole lot of them and hope the caller knows what they're doing. */
2240 remove_edge (a
->succ
);
2242 /* Adjust the edges out of B for the new owner. */
2243 for (e
= b
->succ
; e
; e
= e
->succ_next
)
2247 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
2248 b
->pred
= b
->succ
= NULL
;
2250 /* Reassociate the insns of B with A. */
2253 if (basic_block_for_insn
)
2255 BLOCK_FOR_INSN (b_head
) = a
;
2256 while (b_head
!= b_end
)
2258 b_head
= NEXT_INSN (b_head
);
2259 BLOCK_FOR_INSN (b_head
) = a
;
2269 /* Blocks A and B are to be merged into a single block. A has no incoming
2270 fallthru edge, so it can be moved before B without adding or modifying
2271 any jumps (aside from the jump from A to B). */
2274 merge_blocks_move_predecessor_nojumps (a
, b
)
2277 rtx start
, end
, barrier
;
2283 barrier
= next_nonnote_insn (end
);
2284 if (GET_CODE (barrier
) != BARRIER
)
2286 flow_delete_insn (barrier
);
2288 /* Move block and loop notes out of the chain so that we do not
2289 disturb their order.
2291 ??? A better solution would be to squeeze out all the non-nested notes
2292 and adjust the block trees appropriately. Even better would be to have
2293 a tighter connection between block trees and rtl so that this is not
2295 start
= squeeze_notes (start
, end
);
2297 /* Scramble the insn chain. */
2298 if (end
!= PREV_INSN (b
->head
))
2299 reorder_insns (start
, end
, PREV_INSN (b
->head
));
2303 fprintf (rtl_dump_file
, "Moved block %d before %d and merged.\n",
2304 a
->index
, b
->index
);
2307 /* Swap the records for the two blocks around. Although we are deleting B,
2308 A is now where B was and we want to compact the BB array from where
2310 BASIC_BLOCK(a
->index
) = b
;
2311 BASIC_BLOCK(b
->index
) = a
;
2313 a
->index
= b
->index
;
2316 /* Now blocks A and B are contiguous. Merge them. */
2317 merge_blocks_nomove (a
, b
);
2322 /* Blocks A and B are to be merged into a single block. B has no outgoing
2323 fallthru edge, so it can be moved after A without adding or modifying
2324 any jumps (aside from the jump from A to B). */
2327 merge_blocks_move_successor_nojumps (a
, b
)
2330 rtx start
, end
, barrier
;
2334 barrier
= NEXT_INSN (end
);
2336 /* Recognize a jump table following block B. */
2337 if (GET_CODE (barrier
) == CODE_LABEL
2338 && NEXT_INSN (barrier
)
2339 && GET_CODE (NEXT_INSN (barrier
)) == JUMP_INSN
2340 && (GET_CODE (PATTERN (NEXT_INSN (barrier
))) == ADDR_VEC
2341 || GET_CODE (PATTERN (NEXT_INSN (barrier
))) == ADDR_DIFF_VEC
))
2343 end
= NEXT_INSN (barrier
);
2344 barrier
= NEXT_INSN (end
);
2347 /* There had better have been a barrier there. Delete it. */
2348 if (GET_CODE (barrier
) != BARRIER
)
2350 flow_delete_insn (barrier
);
2352 /* Move block and loop notes out of the chain so that we do not
2353 disturb their order.
2355 ??? A better solution would be to squeeze out all the non-nested notes
2356 and adjust the block trees appropriately. Even better would be to have
2357 a tighter connection between block trees and rtl so that this is not
2359 start
= squeeze_notes (start
, end
);
2361 /* Scramble the insn chain. */
2362 reorder_insns (start
, end
, a
->end
);
2364 /* Now blocks A and B are contiguous. Merge them. */
2365 merge_blocks_nomove (a
, b
);
2369 fprintf (rtl_dump_file
, "Moved block %d after %d and merged.\n",
2370 b
->index
, a
->index
);
2376 /* Attempt to merge basic blocks that are potentially non-adjacent.
2377 Return true iff the attempt succeeded. */
2380 merge_blocks (e
, b
, c
)
2384 /* If C has a tail recursion label, do not merge. There is no
2385 edge recorded from the call_placeholder back to this label, as
2386 that would make optimize_sibling_and_tail_recursive_calls more
2387 complex for no gain. */
2388 if (GET_CODE (c
->head
) == CODE_LABEL
2389 && tail_recursion_label_p (c
->head
))
2392 /* If B has a fallthru edge to C, no need to move anything. */
2393 if (e
->flags
& EDGE_FALLTHRU
)
2395 merge_blocks_nomove (b
, c
);
2399 fprintf (rtl_dump_file
, "Merged %d and %d without moving.\n",
2400 b
->index
, c
->index
);
2409 int c_has_outgoing_fallthru
;
2410 int b_has_incoming_fallthru
;
2412 /* We must make sure to not munge nesting of exception regions,
2413 lexical blocks, and loop notes.
2415 The first is taken care of by requiring that the active eh
2416 region at the end of one block always matches the active eh
2417 region at the beginning of the next block.
2419 The later two are taken care of by squeezing out all the notes. */
2421 /* ??? A throw/catch edge (or any abnormal edge) should be rarely
2422 executed and we may want to treat blocks which have two out
2423 edges, one normal, one abnormal as only having one edge for
2424 block merging purposes. */
2426 for (tmp_edge
= c
->succ
; tmp_edge
; tmp_edge
= tmp_edge
->succ_next
)
2427 if (tmp_edge
->flags
& EDGE_FALLTHRU
)
2429 c_has_outgoing_fallthru
= (tmp_edge
!= NULL
);
2431 for (tmp_edge
= b
->pred
; tmp_edge
; tmp_edge
= tmp_edge
->pred_next
)
2432 if (tmp_edge
->flags
& EDGE_FALLTHRU
)
2434 b_has_incoming_fallthru
= (tmp_edge
!= NULL
);
2436 /* If B does not have an incoming fallthru, and the exception regions
2437 match, then it can be moved immediately before C without introducing
2440 C can not be the first block, so we do not have to worry about
2441 accessing a non-existent block. */
2442 d
= BASIC_BLOCK (c
->index
- 1);
2443 if (! b_has_incoming_fallthru
2444 && d
->eh_end
== b
->eh_beg
2445 && b
->eh_end
== c
->eh_beg
)
2446 return merge_blocks_move_predecessor_nojumps (b
, c
);
2448 /* Otherwise, we're going to try to move C after B. Make sure the
2449 exception regions match.
2451 If B is the last basic block, then we must not try to access the
2452 block structure for block B + 1. Luckily in that case we do not
2453 need to worry about matching exception regions. */
2454 d
= (b
->index
+ 1 < n_basic_blocks
? BASIC_BLOCK (b
->index
+ 1) : NULL
);
2455 if (b
->eh_end
== c
->eh_beg
2456 && (d
== NULL
|| c
->eh_end
== d
->eh_beg
))
2458 /* If C does not have an outgoing fallthru, then it can be moved
2459 immediately after B without introducing or modifying jumps. */
2460 if (! c_has_outgoing_fallthru
)
2461 return merge_blocks_move_successor_nojumps (b
, c
);
2463 /* Otherwise, we'll need to insert an extra jump, and possibly
2464 a new block to contain it. */
2465 /* ??? Not implemented yet. */
2472 /* Top level driver for merge_blocks. */
2479 /* Attempt to merge blocks as made possible by edge removal. If a block
2480 has only one successor, and the successor has only one predecessor,
2481 they may be combined. */
2483 for (i
= 0; i
< n_basic_blocks
; )
2485 basic_block c
, b
= BASIC_BLOCK (i
);
2488 /* A loop because chains of blocks might be combineable. */
2489 while ((s
= b
->succ
) != NULL
2490 && s
->succ_next
== NULL
2491 && (s
->flags
& EDGE_EH
) == 0
2492 && (c
= s
->dest
) != EXIT_BLOCK_PTR
2493 && c
->pred
->pred_next
== NULL
2494 /* If the jump insn has side effects, we can't kill the edge. */
2495 && (GET_CODE (b
->end
) != JUMP_INSN
2496 || onlyjump_p (b
->end
))
2497 && merge_blocks (s
, b
, c
))
2500 /* Don't get confused by the index shift caused by deleting blocks. */
2505 /* The given edge should potentially be a fallthru edge. If that is in
2506 fact true, delete the jump and barriers that are in the way. */
2509 tidy_fallthru_edge (e
, b
, c
)
2515 /* ??? In a late-running flow pass, other folks may have deleted basic
2516 blocks by nopping out blocks, leaving multiple BARRIERs between here
2517 and the target label. They ought to be chastized and fixed.
2519 We can also wind up with a sequence of undeletable labels between
2520 one block and the next.
2522 So search through a sequence of barriers, labels, and notes for
2523 the head of block C and assert that we really do fall through. */
2525 if (next_real_insn (b
->end
) != next_real_insn (PREV_INSN (c
->head
)))
2528 /* Remove what will soon cease being the jump insn from the source block.
2529 If block B consisted only of this single jump, turn it into a deleted
2532 if (GET_CODE (q
) == JUMP_INSN
2534 && (any_uncondjump_p (q
)
2535 || (b
->succ
== e
&& e
->succ_next
== NULL
)))
2538 /* If this was a conditional jump, we need to also delete
2539 the insn that set cc0. */
2540 if (any_condjump_p (q
) && sets_cc0_p (PREV_INSN (q
)))
2547 NOTE_LINE_NUMBER (q
) = NOTE_INSN_DELETED
;
2548 NOTE_SOURCE_FILE (q
) = 0;
2551 b
->end
= q
= PREV_INSN (q
);
2554 /* Selectively unlink the sequence. */
2555 if (q
!= PREV_INSN (c
->head
))
2556 flow_delete_insn_chain (NEXT_INSN (q
), PREV_INSN (c
->head
));
2558 e
->flags
|= EDGE_FALLTHRU
;
2561 /* Fix up edges that now fall through, or rather should now fall through
2562 but previously required a jump around now deleted blocks. Simplify
2563 the search by only examining blocks numerically adjacent, since this
2564 is how find_basic_blocks created them. */
2567 tidy_fallthru_edges ()
2571 for (i
= 1; i
< n_basic_blocks
; ++i
)
2573 basic_block b
= BASIC_BLOCK (i
- 1);
2574 basic_block c
= BASIC_BLOCK (i
);
2577 /* We care about simple conditional or unconditional jumps with
2580 If we had a conditional branch to the next instruction when
2581 find_basic_blocks was called, then there will only be one
2582 out edge for the block which ended with the conditional
2583 branch (since we do not create duplicate edges).
2585 Furthermore, the edge will be marked as a fallthru because we
2586 merge the flags for the duplicate edges. So we do not want to
2587 check that the edge is not a FALLTHRU edge. */
2588 if ((s
= b
->succ
) != NULL
2589 && s
->succ_next
== NULL
2591 /* If the jump insn has side effects, we can't tidy the edge. */
2592 && (GET_CODE (b
->end
) != JUMP_INSN
2593 || onlyjump_p (b
->end
)))
2594 tidy_fallthru_edge (s
, b
, c
);
2598 /* Perform data flow analysis.
2599 F is the first insn of the function; FLAGS is a set of PROP_* flags
2600 to be used in accumulating flow info. */
2603 life_analysis (f
, file
, flags
)
2608 #ifdef ELIMINABLE_REGS
2610 static struct {int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
2613 /* Record which registers will be eliminated. We use this in
2616 CLEAR_HARD_REG_SET (elim_reg_set
);
2618 #ifdef ELIMINABLE_REGS
2619 for (i
= 0; i
< (int) (sizeof eliminables
/ sizeof eliminables
[0]); i
++)
2620 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
2622 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
2626 flags
&= PROP_DEATH_NOTES
| PROP_REG_INFO
;
2628 /* The post-reload life analysis have (on a global basis) the same
2629 registers live as was computed by reload itself. elimination
2630 Otherwise offsets and such may be incorrect.
2632 Reload will make some registers as live even though they do not
2635 We don't want to create new auto-incs after reload, since they
2636 are unlikely to be useful and can cause problems with shared
2638 if (reload_completed
)
2639 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
2641 /* We want alias analysis information for local dead store elimination. */
2642 if (flags
& PROP_SCAN_DEAD_CODE
)
2643 init_alias_analysis ();
2645 /* Always remove no-op moves. Do this before other processing so
2646 that we don't have to keep re-scanning them. */
2647 delete_noop_moves (f
);
2649 /* Some targets can emit simpler epilogues if they know that sp was
2650 not ever modified during the function. After reload, of course,
2651 we've already emitted the epilogue so there's no sense searching. */
2652 if (! reload_completed
)
2653 notice_stack_pointer_modification (f
);
2655 /* Allocate and zero out data structures that will record the
2656 data from lifetime analysis. */
2657 allocate_reg_life_data ();
2658 allocate_bb_life_data ();
2660 /* Find the set of registers live on function exit. */
2661 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
2663 /* "Update" life info from zero. It'd be nice to begin the
2664 relaxation with just the exit and noreturn blocks, but that set
2665 is not immediately handy. */
2667 if (flags
& PROP_REG_INFO
)
2668 memset (regs_ever_live
, 0, sizeof(regs_ever_live
));
2669 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
2672 if (flags
& PROP_SCAN_DEAD_CODE
)
2673 end_alias_analysis ();
2676 dump_flow_info (file
);
2678 free_basic_block_vars (1);
2681 /* A subroutine of verify_wide_reg, called through for_each_rtx.
2682 Search for REGNO. If found, abort if it is not wider than word_mode. */
2685 verify_wide_reg_1 (px
, pregno
)
2690 unsigned int regno
= *(int *) pregno
;
2692 if (GET_CODE (x
) == REG
&& REGNO (x
) == regno
)
2694 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
2701 /* A subroutine of verify_local_live_at_start. Search through insns
2702 between HEAD and END looking for register REGNO. */
2705 verify_wide_reg (regno
, head
, end
)
2712 && for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
))
2716 head
= NEXT_INSN (head
);
2719 /* We didn't find the register at all. Something's way screwy. */
2723 /* A subroutine of update_life_info. Verify that there are no untoward
2724 changes in live_at_start during a local update. */
2727 verify_local_live_at_start (new_live_at_start
, bb
)
2728 regset new_live_at_start
;
2731 if (reload_completed
)
2733 /* After reload, there are no pseudos, nor subregs of multi-word
2734 registers. The regsets should exactly match. */
2735 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
2742 /* Find the set of changed registers. */
2743 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
2745 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
,
2747 /* No registers should die. */
2748 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
2750 /* Verify that the now-live register is wider than word_mode. */
2751 verify_wide_reg (i
, bb
->head
, bb
->end
);
2756 /* Updates life information starting with the basic blocks set in BLOCKS.
2757 If BLOCKS is null, consider it to be the universal set.
2759 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
2760 we are only expecting local modifications to basic blocks. If we find
2761 extra registers live at the beginning of a block, then we either killed
2762 useful data, or we have a broken split that wants data not provided.
2763 If we find registers removed from live_at_start, that means we have
2764 a broken peephole that is killing a register it shouldn't.
2766 ??? This is not true in one situation -- when a pre-reload splitter
2767 generates subregs of a multi-word pseudo, current life analysis will
2768 lose the kill. So we _can_ have a pseudo go live. How irritating.
2770 Including PROP_REG_INFO does not properly refresh regs_ever_live
2771 unless the caller resets it to zero. */
2774 update_life_info (blocks
, extent
, prop_flags
)
2776 enum update_life_extent extent
;
2780 regset_head tmp_head
;
2783 tmp
= INITIALIZE_REG_SET (tmp_head
);
2785 /* For a global update, we go through the relaxation process again. */
2786 if (extent
!= UPDATE_LIFE_LOCAL
)
2788 calculate_global_regs_live (blocks
, blocks
,
2789 prop_flags
& PROP_SCAN_DEAD_CODE
);
2791 /* If asked, remove notes from the blocks we'll update. */
2792 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
2793 count_or_remove_death_notes (blocks
, 1);
2798 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
2800 basic_block bb
= BASIC_BLOCK (i
);
2802 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
2803 propagate_block (bb
, tmp
, (regset
) NULL
, prop_flags
);
2805 if (extent
== UPDATE_LIFE_LOCAL
)
2806 verify_local_live_at_start (tmp
, bb
);
2811 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
2813 basic_block bb
= BASIC_BLOCK (i
);
2815 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
2816 propagate_block (bb
, tmp
, (regset
) NULL
, prop_flags
);
2818 if (extent
== UPDATE_LIFE_LOCAL
)
2819 verify_local_live_at_start (tmp
, bb
);
2825 if (prop_flags
& PROP_REG_INFO
)
2827 /* The only pseudos that are live at the beginning of the function
2828 are those that were not set anywhere in the function. local-alloc
2829 doesn't know how to handle these correctly, so mark them as not
2830 local to any one basic block. */
2831 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
2832 FIRST_PSEUDO_REGISTER
, i
,
2833 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
2835 /* We have a problem with any pseudoreg that lives across the setjmp.
2836 ANSI says that if a user variable does not change in value between
2837 the setjmp and the longjmp, then the longjmp preserves it. This
2838 includes longjmp from a place where the pseudo appears dead.
2839 (In principle, the value still exists if it is in scope.)
2840 If the pseudo goes in a hard reg, some other value may occupy
2841 that hard reg where this pseudo is dead, thus clobbering the pseudo.
2842 Conclusion: such a pseudo must not go in a hard reg. */
2843 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
2844 FIRST_PSEUDO_REGISTER
, i
,
2846 if (regno_reg_rtx
[i
] != 0)
2848 REG_LIVE_LENGTH (i
) = -1;
2849 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
2855 /* Free the variables allocated by find_basic_blocks.
2857 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
2860 free_basic_block_vars (keep_head_end_p
)
2861 int keep_head_end_p
;
2863 if (basic_block_for_insn
)
2865 VARRAY_FREE (basic_block_for_insn
);
2866 basic_block_for_insn
= NULL
;
2869 if (! keep_head_end_p
)
2872 VARRAY_FREE (basic_block_info
);
2875 ENTRY_BLOCK_PTR
->aux
= NULL
;
2876 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
2877 EXIT_BLOCK_PTR
->aux
= NULL
;
2878 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
2882 /* Return nonzero if the destination of SET equals the source. */
2887 rtx src
= SET_SRC (set
);
2888 rtx dst
= SET_DEST (set
);
2890 if (GET_CODE (src
) == SUBREG
&& GET_CODE (dst
) == SUBREG
)
2892 if (SUBREG_WORD (src
) != SUBREG_WORD (dst
))
2894 src
= SUBREG_REG (src
);
2895 dst
= SUBREG_REG (dst
);
2898 return (GET_CODE (src
) == REG
&& GET_CODE (dst
) == REG
2899 && REGNO (src
) == REGNO (dst
));
2902 /* Return nonzero if an insn consists only of SETs, each of which only sets a
2908 rtx pat
= PATTERN (insn
);
2910 /* Insns carrying these notes are useful later on. */
2911 if (find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
2914 if (GET_CODE (pat
) == SET
&& set_noop_p (pat
))
2917 if (GET_CODE (pat
) == PARALLEL
)
2920 /* If nothing but SETs of registers to themselves,
2921 this insn can also be deleted. */
2922 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2924 rtx tem
= XVECEXP (pat
, 0, i
);
2926 if (GET_CODE (tem
) == USE
2927 || GET_CODE (tem
) == CLOBBER
)
2930 if (GET_CODE (tem
) != SET
|| ! set_noop_p (tem
))
2939 /* Delete any insns that copy a register to itself. */
2942 delete_noop_moves (f
)
2946 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2948 if (GET_CODE (insn
) == INSN
&& noop_move_p (insn
))
2950 PUT_CODE (insn
, NOTE
);
2951 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
2952 NOTE_SOURCE_FILE (insn
) = 0;
2957 /* Determine if the stack pointer is constant over the life of the function.
2958 Only useful before prologues have been emitted. */
2961 notice_stack_pointer_modification_1 (x
, pat
, data
)
2963 rtx pat ATTRIBUTE_UNUSED
;
2964 void *data ATTRIBUTE_UNUSED
;
2966 if (x
== stack_pointer_rtx
2967 /* The stack pointer is only modified indirectly as the result
2968 of a push until later in flow. See the comments in rtl.texi
2969 regarding Embedded Side-Effects on Addresses. */
2970 || (GET_CODE (x
) == MEM
2971 && (GET_CODE (XEXP (x
, 0)) == PRE_DEC
2972 || GET_CODE (XEXP (x
, 0)) == PRE_INC
2973 || GET_CODE (XEXP (x
, 0)) == POST_DEC
2974 || GET_CODE (XEXP (x
, 0)) == POST_INC
)
2975 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
2976 current_function_sp_is_unchanging
= 0;
2980 notice_stack_pointer_modification (f
)
2985 /* Assume that the stack pointer is unchanging if alloca hasn't
2987 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
2988 if (! current_function_sp_is_unchanging
)
2991 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2995 /* Check if insn modifies the stack pointer. */
2996 note_stores (PATTERN (insn
), notice_stack_pointer_modification_1
,
2998 if (! current_function_sp_is_unchanging
)
3004 /* Mark a register in SET. Hard registers in large modes get all
3005 of their component registers set as well. */
3007 mark_reg (reg
, xset
)
3011 regset set
= (regset
) xset
;
3012 int regno
= REGNO (reg
);
3014 if (GET_MODE (reg
) == BLKmode
)
3017 SET_REGNO_REG_SET (set
, regno
);
3018 if (regno
< FIRST_PSEUDO_REGISTER
)
3020 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
3022 SET_REGNO_REG_SET (set
, regno
+ n
);
3026 /* Mark those regs which are needed at the end of the function as live
3027 at the end of the last basic block. */
3029 mark_regs_live_at_end (set
)
3034 /* If exiting needs the right stack value, consider the stack pointer
3035 live at the end of the function. */
3036 if ((HAVE_epilogue
&& reload_completed
)
3037 || ! EXIT_IGNORE_STACK
3038 || (! FRAME_POINTER_REQUIRED
3039 && ! current_function_calls_alloca
3040 && flag_omit_frame_pointer
)
3041 || current_function_sp_is_unchanging
)
3043 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
3046 /* Mark the frame pointer if needed at the end of the function. If
3047 we end up eliminating it, it will be removed from the live list
3048 of each basic block by reload. */
3050 if (! reload_completed
|| frame_pointer_needed
)
3052 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
3053 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3054 /* If they are different, also mark the hard frame pointer as live */
3055 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
3059 #ifdef PIC_OFFSET_TABLE_REGNUM
3060 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
3061 /* Many architectures have a GP register even without flag_pic.
3062 Assume the pic register is not in use, or will be handled by
3063 other means, if it is not fixed. */
3064 if (fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
3065 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
3069 /* Mark all global registers, and all registers used by the epilogue
3070 as being live at the end of the function since they may be
3071 referenced by our caller. */
3072 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3074 #ifdef EPILOGUE_USES
3075 || EPILOGUE_USES (i
)
3078 SET_REGNO_REG_SET (set
, i
);
3080 /* Mark all call-saved registers that we actaully used. */
3081 if (HAVE_epilogue
&& reload_completed
)
3083 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3084 if (! call_used_regs
[i
] && regs_ever_live
[i
])
3085 SET_REGNO_REG_SET (set
, i
);
3088 /* Mark function return value. */
3089 diddle_return_value (mark_reg
, set
);
3092 /* Callback function for for_each_successor_phi. DATA is a regset.
3093 Sets the SRC_REGNO, the regno of the phi alternative for phi node
3094 INSN, in the regset. */
3097 set_phi_alternative_reg (insn
, dest_regno
, src_regno
, data
)
3098 rtx insn ATTRIBUTE_UNUSED
;
3099 int dest_regno ATTRIBUTE_UNUSED
;
3103 regset live
= (regset
) data
;
3104 SET_REGNO_REG_SET (live
, src_regno
);
3108 /* Propagate global life info around the graph of basic blocks. Begin
3109 considering blocks with their corresponding bit set in BLOCKS_IN.
3110 If BLOCKS_IN is null, consider it the universal set.
3112 BLOCKS_OUT is set for every block that was changed. */
3115 calculate_global_regs_live (blocks_in
, blocks_out
, flags
)
3116 sbitmap blocks_in
, blocks_out
;
3119 basic_block
*queue
, *qhead
, *qtail
, *qend
;
3120 regset tmp
, new_live_at_end
;
3121 regset_head tmp_head
;
3122 regset_head new_live_at_end_head
;
3125 tmp
= INITIALIZE_REG_SET (tmp_head
);
3126 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
3128 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
3129 because the `head == tail' style test for an empty queue doesn't
3130 work with a full queue. */
3131 queue
= (basic_block
*) xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
3133 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
3135 /* Clear out the garbage that might be hanging out in bb->aux. */
3136 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
3137 BASIC_BLOCK (i
)->aux
= NULL
;
3139 /* Queue the blocks set in the initial mask. Do this in reverse block
3140 number order so that we are more likely for the first round to do
3141 useful work. We use AUX non-null to flag that the block is queued. */
3144 EXECUTE_IF_SET_IN_SBITMAP (blocks_in
, 0, i
,
3146 basic_block bb
= BASIC_BLOCK (i
);
3153 for (i
= 0; i
< n_basic_blocks
; ++i
)
3155 basic_block bb
= BASIC_BLOCK (i
);
3162 sbitmap_zero (blocks_out
);
3164 while (qhead
!= qtail
)
3166 int rescan
, changed
;
3175 /* Begin by propogating live_at_start from the successor blocks. */
3176 CLEAR_REG_SET (new_live_at_end
);
3177 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
3179 basic_block sb
= e
->dest
;
3180 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
3183 /* Force the stack pointer to be live -- which might not already be
3184 the case for blocks within infinite loops. */
3185 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
3187 /* Regs used in phi nodes are not included in
3188 global_live_at_start, since they are live only along a
3189 particular edge. Set those regs that are live because of a
3190 phi node alternative corresponding to this particular block. */
3192 for_each_successor_phi (bb
, &set_phi_alternative_reg
,
3195 if (bb
== ENTRY_BLOCK_PTR
)
3197 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
3201 /* On our first pass through this block, we'll go ahead and continue.
3202 Recognize first pass by local_set NULL. On subsequent passes, we
3203 get to skip out early if live_at_end wouldn't have changed. */
3205 if (bb
->local_set
== NULL
)
3207 bb
->local_set
= OBSTACK_ALLOC_REG_SET (function_obstack
);
3212 /* If any bits were removed from live_at_end, we'll have to
3213 rescan the block. This wouldn't be necessary if we had
3214 precalculated local_live, however with PROP_SCAN_DEAD_CODE
3215 local_live is really dependent on live_at_end. */
3216 CLEAR_REG_SET (tmp
);
3217 rescan
= bitmap_operation (tmp
, bb
->global_live_at_end
,
3218 new_live_at_end
, BITMAP_AND_COMPL
);
3222 /* Find the set of changed bits. Take this opportunity
3223 to notice that this set is empty and early out. */
3224 CLEAR_REG_SET (tmp
);
3225 changed
= bitmap_operation (tmp
, bb
->global_live_at_end
,
3226 new_live_at_end
, BITMAP_XOR
);
3230 /* If any of the changed bits overlap with local_set,
3231 we'll have to rescan the block. Detect overlap by
3232 the AND with ~local_set turning off bits. */
3233 rescan
= bitmap_operation (tmp
, tmp
, bb
->local_set
,
3238 /* Let our caller know that BB changed enough to require its
3239 death notes updated. */
3241 SET_BIT (blocks_out
, bb
->index
);
3245 /* Add to live_at_start the set of all registers in
3246 new_live_at_end that aren't in the old live_at_end. */
3248 bitmap_operation (tmp
, new_live_at_end
, bb
->global_live_at_end
,
3250 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
3252 changed
= bitmap_operation (bb
->global_live_at_start
,
3253 bb
->global_live_at_start
,
3260 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
3262 /* Rescan the block insn by insn to turn (a copy of) live_at_end
3263 into live_at_start. */
3264 propagate_block (bb
, new_live_at_end
, bb
->local_set
, flags
);
3266 /* If live_at start didn't change, no need to go farther. */
3267 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
3270 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
3273 /* Queue all predecessors of BB so that we may re-examine
3274 their live_at_end. */
3275 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
3277 basic_block pb
= e
->src
;
3278 if (pb
->aux
== NULL
)
3289 FREE_REG_SET (new_live_at_end
);
3293 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
3295 basic_block bb
= BASIC_BLOCK (i
);
3296 FREE_REG_SET (bb
->local_set
);
3301 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
3303 basic_block bb
= BASIC_BLOCK (i
);
3304 FREE_REG_SET (bb
->local_set
);
3311 /* Subroutines of life analysis. */
3313 /* Allocate the permanent data structures that represent the results
3314 of life analysis. Not static since used also for stupid life analysis. */
3317 allocate_bb_life_data ()
3321 for (i
= 0; i
< n_basic_blocks
; i
++)
3323 basic_block bb
= BASIC_BLOCK (i
);
3325 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (function_obstack
);
3326 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (function_obstack
);
3329 ENTRY_BLOCK_PTR
->global_live_at_end
3330 = OBSTACK_ALLOC_REG_SET (function_obstack
);
3331 EXIT_BLOCK_PTR
->global_live_at_start
3332 = OBSTACK_ALLOC_REG_SET (function_obstack
);
3334 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (function_obstack
);
3338 allocate_reg_life_data ()
3342 max_regno
= max_reg_num ();
3344 /* Recalculate the register space, in case it has grown. Old style
3345 vector oriented regsets would set regset_{size,bytes} here also. */
3346 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3348 /* Reset all the data we'll collect in propagate_block and its
3350 for (i
= 0; i
< max_regno
; i
++)
3354 REG_N_DEATHS (i
) = 0;
3355 REG_N_CALLS_CROSSED (i
) = 0;
3356 REG_LIVE_LENGTH (i
) = 0;
3357 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
3361 /* Delete dead instructions for propagate_block. */
3364 propagate_block_delete_insn (bb
, insn
)
3368 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
3370 /* If the insn referred to a label, and that label was attached to
3371 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
3372 pretty much mandatory to delete it, because the ADDR_VEC may be
3373 referencing labels that no longer exist. */
3377 rtx label
= XEXP (inote
, 0);
3380 if (LABEL_NUSES (label
) == 1
3381 && (next
= next_nonnote_insn (label
)) != NULL
3382 && GET_CODE (next
) == JUMP_INSN
3383 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
3384 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
3386 rtx pat
= PATTERN (next
);
3387 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
3388 int len
= XVECLEN (pat
, diff_vec_p
);
3391 for (i
= 0; i
< len
; i
++)
3392 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
3394 flow_delete_insn (next
);
3398 if (bb
->end
== insn
)
3399 bb
->end
= PREV_INSN (insn
);
3400 flow_delete_insn (insn
);
3403 /* Delete dead libcalls for propagate_block. Return the insn
3404 before the libcall. */
3407 propagate_block_delete_libcall (bb
, insn
, note
)
3411 rtx first
= XEXP (note
, 0);
3412 rtx before
= PREV_INSN (first
);
3414 if (insn
== bb
->end
)
3417 flow_delete_insn_chain (first
, insn
);
3421 /* Update the life-status of regs for one insn. Return the previous insn. */
3424 propagate_one_insn (pbi
, insn
)
3425 struct propagate_block_info
*pbi
;
3428 rtx prev
= PREV_INSN (insn
);
3429 int flags
= pbi
->flags
;
3430 int insn_is_dead
= 0;
3431 int libcall_is_dead
= 0;
3435 if (! INSN_P (insn
))
3438 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
3439 if (flags
& PROP_SCAN_DEAD_CODE
)
3441 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0,
3443 libcall_is_dead
= (insn_is_dead
&& note
!= 0
3444 && libcall_dead_p (pbi
, note
, insn
));
3447 /* We almost certainly don't want to delete prologue or epilogue
3448 instructions. Warn about probable compiler losage. */
3451 && (((HAVE_epilogue
|| HAVE_prologue
)
3452 && prologue_epilogue_contains (insn
))
3453 || (HAVE_sibcall_epilogue
3454 && sibcall_epilogue_contains (insn
)))
3455 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
3457 if (flags
& PROP_KILL_DEAD_CODE
)
3459 warning ("ICE: would have deleted prologue/epilogue insn");
3460 if (!inhibit_warnings
)
3463 libcall_is_dead
= insn_is_dead
= 0;
3466 /* If an instruction consists of just dead store(s) on final pass,
3468 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
3470 /* Record sets. Do this even for dead instructions, since they
3471 would have killed the values if they hadn't been deleted. */
3472 mark_set_regs (pbi
, PATTERN (insn
), insn
);
3474 /* CC0 is now known to be dead. Either this insn used it,
3475 in which case it doesn't anymore, or clobbered it,
3476 so the next insn can't use it. */
3479 if (libcall_is_dead
)
3481 prev
= propagate_block_delete_libcall (pbi
->bb
, insn
, note
);
3482 insn
= NEXT_INSN (prev
);
3485 propagate_block_delete_insn (pbi
->bb
, insn
);
3490 /* See if this is an increment or decrement that can be merged into
3491 a following memory address. */
3494 register rtx x
= single_set (insn
);
3496 /* Does this instruction increment or decrement a register? */
3497 if ((flags
& PROP_AUTOINC
)
3499 && GET_CODE (SET_DEST (x
)) == REG
3500 && (GET_CODE (SET_SRC (x
)) == PLUS
3501 || GET_CODE (SET_SRC (x
)) == MINUS
)
3502 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
3503 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
3504 /* Ok, look for a following memory ref we can combine with.
3505 If one is found, change the memory ref to a PRE_INC
3506 or PRE_DEC, cancel this insn, and return 1.
3507 Return 0 if nothing has been done. */
3508 && try_pre_increment_1 (pbi
, insn
))
3511 #endif /* AUTO_INC_DEC */
3513 CLEAR_REG_SET (pbi
->new_set
);
3515 /* If this is not the final pass, and this insn is copying the value of
3516 a library call and it's dead, don't scan the insns that perform the
3517 library call, so that the call's arguments are not marked live. */
3518 if (libcall_is_dead
)
3520 /* Record the death of the dest reg. */
3521 mark_set_regs (pbi
, PATTERN (insn
), insn
);
3523 insn
= XEXP (note
, 0);
3524 return PREV_INSN (insn
);
3526 else if (GET_CODE (PATTERN (insn
)) == SET
3527 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
3528 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
3529 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
3530 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
3531 /* We have an insn to pop a constant amount off the stack.
3532 (Such insns use PLUS regardless of the direction of the stack,
3533 and any insn to adjust the stack by a constant is always a pop.)
3534 These insns, if not dead stores, have no effect on life. */
3538 /* Any regs live at the time of a call instruction must not go
3539 in a register clobbered by calls. Find all regs now live and
3540 record this for them. */
3542 if (GET_CODE (insn
) == CALL_INSN
&& (flags
& PROP_REG_INFO
))
3543 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
3544 { REG_N_CALLS_CROSSED (i
)++; });
3546 /* Record sets. Do this even for dead instructions, since they
3547 would have killed the values if they hadn't been deleted. */
3548 mark_set_regs (pbi
, PATTERN (insn
), insn
);
3550 if (GET_CODE (insn
) == CALL_INSN
)
3556 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
3557 cond
= COND_EXEC_TEST (PATTERN (insn
));
3559 /* Non-constant calls clobber memory. */
3560 if (! CONST_CALL_P (insn
))
3561 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3563 /* There may be extra registers to be clobbered. */
3564 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
3566 note
= XEXP (note
, 1))
3567 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
3568 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
3569 cond
, insn
, pbi
->flags
);
3571 /* Calls change all call-used and global registers. */
3572 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3573 if (call_used_regs
[i
] && ! global_regs
[i
]
3576 /* We do not want REG_UNUSED notes for these registers. */
3577 mark_set_1 (pbi
, CLOBBER
, gen_rtx_REG (reg_raw_mode
[i
], i
),
3579 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
3583 /* If an insn doesn't use CC0, it becomes dead since we assume
3584 that every insn clobbers it. So show it dead here;
3585 mark_used_regs will set it live if it is referenced. */
3590 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
3592 /* Sometimes we may have inserted something before INSN (such as a move)
3593 when we make an auto-inc. So ensure we will scan those insns. */
3595 prev
= PREV_INSN (insn
);
3598 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
3604 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
3605 cond
= COND_EXEC_TEST (PATTERN (insn
));
3607 /* Calls use their arguments. */
3608 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
3610 note
= XEXP (note
, 1))
3611 if (GET_CODE (XEXP (note
, 0)) == USE
)
3612 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0),
3615 /* The stack ptr is used (honorarily) by a CALL insn. */
3616 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
3618 /* Calls may also reference any of the global registers,
3619 so they are made live. */
3620 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
3622 mark_used_reg (pbi
, gen_rtx_REG (reg_raw_mode
[i
], i
),
3627 /* On final pass, update counts of how many insns in which each reg
3629 if (flags
& PROP_REG_INFO
)
3630 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
3631 { REG_LIVE_LENGTH (i
)++; });
3636 /* Initialize a propagate_block_info struct for public consumption.
3637 Note that the structure itself is opaque to this file, but that
3638 the user can use the regsets provided here. */
3640 struct propagate_block_info
*
3641 init_propagate_block_info (bb
, live
, local_set
, flags
)
3647 struct propagate_block_info
*pbi
= xmalloc (sizeof(*pbi
));
3650 pbi
->reg_live
= live
;
3651 pbi
->mem_set_list
= NULL_RTX
;
3652 pbi
->local_set
= local_set
;
3656 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3657 pbi
->reg_next_use
= (rtx
*) xcalloc (max_reg_num (), sizeof (rtx
));
3659 pbi
->reg_next_use
= NULL
;
3661 pbi
->new_set
= BITMAP_XMALLOC ();
3663 #ifdef HAVE_conditional_execution
3664 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
3665 free_reg_cond_life_info
);
3666 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
3668 /* If this block ends in a conditional branch, for each register live
3669 from one side of the branch and not the other, record the register
3670 as conditionally dead. */
3671 if ((flags
& (PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
))
3672 && GET_CODE (bb
->end
) == JUMP_INSN
3673 && any_condjump_p (bb
->end
))
3675 regset_head diff_head
;
3676 regset diff
= INITIALIZE_REG_SET (diff_head
);
3677 basic_block bb_true
, bb_false
;
3678 rtx cond_true
, cond_false
, set_src
;
3681 /* Identify the successor blocks. */
3682 bb_true
= bb
->succ
->dest
;
3683 if (bb
->succ
->succ_next
!= NULL
)
3685 bb_false
= bb
->succ
->succ_next
->dest
;
3687 if (bb
->succ
->flags
& EDGE_FALLTHRU
)
3689 basic_block t
= bb_false
;
3693 else if (! (bb
->succ
->succ_next
->flags
& EDGE_FALLTHRU
))
3698 /* This can happen with a conditional jump to the next insn. */
3699 if (JUMP_LABEL (bb
->end
) != bb_true
->head
)
3702 /* Simplest way to do nothing. */
3706 /* Extract the condition from the branch. */
3707 set_src
= SET_SRC (pc_set (bb
->end
));
3708 cond_true
= XEXP (set_src
, 0);
3709 cond_false
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true
)),
3710 GET_MODE (cond_true
), XEXP (cond_true
, 0),
3711 XEXP (cond_true
, 1));
3712 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
3715 cond_false
= cond_true
;
3719 /* Compute which register lead different lives in the successors. */
3720 if (bitmap_operation (diff
, bb_true
->global_live_at_start
,
3721 bb_false
->global_live_at_start
, BITMAP_XOR
))
3723 if (GET_CODE (XEXP (cond_true
, 0)) != REG
)
3725 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond_true
, 0)));
3727 /* For each such register, mark it conditionally dead. */
3728 EXECUTE_IF_SET_IN_REG_SET
3731 struct reg_cond_life_info
*rcli
;
3734 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
3736 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
3740 rcli
->condition
= alloc_EXPR_LIST (0, cond
, NULL_RTX
);
3742 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3743 (splay_tree_value
) rcli
);
3747 FREE_REG_SET (diff
);
3751 /* If this block has no successors, any stores to the frame that aren't
3752 used later in the block are dead. So make a pass over the block
3753 recording any such that are made and show them dead at the end. We do
3754 a very conservative and simple job here. */
3755 if ((flags
& PROP_SCAN_DEAD_CODE
)
3756 && (bb
->succ
== NULL
3757 || (bb
->succ
->succ_next
== NULL
3758 && bb
->succ
->dest
== EXIT_BLOCK_PTR
)))
3761 for (insn
= bb
->end
; insn
!= bb
->head
; insn
= PREV_INSN (insn
))
3762 if (GET_CODE (insn
) == INSN
3763 && GET_CODE (PATTERN (insn
)) == SET
3764 && GET_CODE (SET_DEST (PATTERN (insn
))) == MEM
)
3766 rtx mem
= SET_DEST (PATTERN (insn
));
3768 if (XEXP (mem
, 0) == frame_pointer_rtx
3769 || (GET_CODE (XEXP (mem
, 0)) == PLUS
3770 && XEXP (XEXP (mem
, 0), 0) == frame_pointer_rtx
3771 && GET_CODE (XEXP (XEXP (mem
, 0), 1)) == CONST_INT
))
3772 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
3779 /* Release a propagate_block_info struct. */
3782 free_propagate_block_info (pbi
)
3783 struct propagate_block_info
*pbi
;
3785 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3787 BITMAP_XFREE (pbi
->new_set
);
3789 #ifdef HAVE_conditional_execution
3790 splay_tree_delete (pbi
->reg_cond_dead
);
3791 BITMAP_XFREE (pbi
->reg_cond_reg
);
3794 if (pbi
->reg_next_use
)
3795 free (pbi
->reg_next_use
);
3800 /* Compute the registers live at the beginning of a basic block BB from
3801 those live at the end.
3803 When called, REG_LIVE contains those live at the end. On return, it
3804 contains those live at the beginning.
3806 LOCAL_SET, if non-null, will be set with all registers killed by
3807 this basic block. */
3810 propagate_block (bb
, live
, local_set
, flags
)
3816 struct propagate_block_info
*pbi
;
3819 pbi
= init_propagate_block_info (bb
, live
, local_set
, flags
);
3821 if (flags
& PROP_REG_INFO
)
3825 /* Process the regs live at the end of the block.
3826 Mark them as not local to any one basic block. */
3827 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
3828 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
3831 /* Scan the block an insn at a time from end to beginning. */
3833 for (insn
= bb
->end
; ; insn
= prev
)
3835 /* If this is a call to `setjmp' et al, warn if any
3836 non-volatile datum is live. */
3837 if ((flags
& PROP_REG_INFO
)
3838 && GET_CODE (insn
) == NOTE
3839 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_SETJMP
)
3840 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
3842 prev
= propagate_one_insn (pbi
, insn
);
3844 if (insn
== bb
->head
)
3848 free_propagate_block_info (pbi
);
3851 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
3852 (SET expressions whose destinations are registers dead after the insn).
3853 NEEDED is the regset that says which regs are alive after the insn.
3855 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
3857 If X is the entire body of an insn, NOTES contains the reg notes
3858 pertaining to the insn. */
3861 insn_dead_p (pbi
, x
, call_ok
, notes
)
3862 struct propagate_block_info
*pbi
;
3865 rtx notes ATTRIBUTE_UNUSED
;
3867 enum rtx_code code
= GET_CODE (x
);
3870 /* If flow is invoked after reload, we must take existing AUTO_INC
3871 expresions into account. */
3872 if (reload_completed
)
3874 for ( ; notes
; notes
= XEXP (notes
, 1))
3876 if (REG_NOTE_KIND (notes
) == REG_INC
)
3878 int regno
= REGNO (XEXP (notes
, 0));
3880 /* Don't delete insns to set global regs. */
3881 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
3882 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3889 /* If setting something that's a reg or part of one,
3890 see if that register's altered value will be live. */
3894 rtx r
= SET_DEST (x
);
3897 if (GET_CODE (r
) == CC0
)
3898 return ! pbi
->cc0_live
;
3901 /* A SET that is a subroutine call cannot be dead. */
3902 if (GET_CODE (SET_SRC (x
)) == CALL
)
3908 /* Don't eliminate loads from volatile memory or volatile asms. */
3909 else if (volatile_refs_p (SET_SRC (x
)))
3912 if (GET_CODE (r
) == MEM
)
3916 if (MEM_VOLATILE_P (r
))
3919 /* Walk the set of memory locations we are currently tracking
3920 and see if one is an identical match to this memory location.
3921 If so, this memory write is dead (remember, we're walking
3922 backwards from the end of the block to the start). */
3923 temp
= pbi
->mem_set_list
;
3926 if (rtx_equal_p (XEXP (temp
, 0), r
))
3928 temp
= XEXP (temp
, 1);
3933 while (GET_CODE (r
) == SUBREG
3934 || GET_CODE (r
) == STRICT_LOW_PART
3935 || GET_CODE (r
) == ZERO_EXTRACT
)
3938 if (GET_CODE (r
) == REG
)
3940 int regno
= REGNO (r
);
3943 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3946 /* If this is a hard register, verify that subsequent
3947 words are not needed. */
3948 if (regno
< FIRST_PSEUDO_REGISTER
)
3950 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
3953 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
3957 /* Don't delete insns to set global regs. */
3958 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
3961 /* Make sure insns to set the stack pointer aren't deleted. */
3962 if (regno
== STACK_POINTER_REGNUM
)
3965 /* Make sure insns to set the frame pointer aren't deleted. */
3966 if (regno
== FRAME_POINTER_REGNUM
3967 && (! reload_completed
|| frame_pointer_needed
))
3969 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3970 if (regno
== HARD_FRAME_POINTER_REGNUM
3971 && (! reload_completed
|| frame_pointer_needed
))
3975 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3976 /* Make sure insns to set arg pointer are never deleted
3977 (if the arg pointer isn't fixed, there will be a USE
3978 for it, so we can treat it normally). */
3979 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3983 #ifdef PIC_OFFSET_TABLE_REGNUM
3984 /* Before reload, do not allow sets of the pic register
3985 to be deleted. Reload can insert references to
3986 constant pool memory anywhere in the function, making
3987 the PIC register live where it wasn't before. */
3988 if (regno
== PIC_OFFSET_TABLE_REGNUM
&& fixed_regs
[regno
]
3989 && ! reload_completed
)
3993 /* Otherwise, the set is dead. */
3999 /* If performing several activities, insn is dead if each activity
4000 is individually dead. Also, CLOBBERs and USEs can be ignored; a
4001 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
4003 else if (code
== PARALLEL
)
4005 int i
= XVECLEN (x
, 0);
4007 for (i
--; i
>= 0; i
--)
4008 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
4009 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
4010 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
4016 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
4017 is not necessarily true for hard registers. */
4018 else if (code
== CLOBBER
&& GET_CODE (XEXP (x
, 0)) == REG
4019 && REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
4020 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
4023 /* We do not check other CLOBBER or USE here. An insn consisting of just
4024 a CLOBBER or just a USE should not be deleted. */
4028 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
4029 return 1 if the entire library call is dead.
4030 This is true if INSN copies a register (hard or pseudo)
4031 and if the hard return reg of the call insn is dead.
4032 (The caller should have tested the destination of the SET inside
4033 INSN already for death.)
4035 If this insn doesn't just copy a register, then we don't
4036 have an ordinary libcall. In that case, cse could not have
4037 managed to substitute the source for the dest later on,
4038 so we can assume the libcall is dead.
4040 PBI is the block info giving pseudoregs live before this insn.
4041 NOTE is the REG_RETVAL note of the insn. */
4044 libcall_dead_p (pbi
, note
, insn
)
4045 struct propagate_block_info
*pbi
;
4049 rtx x
= single_set (insn
);
4053 register rtx r
= SET_SRC (x
);
4054 if (GET_CODE (r
) == REG
)
4056 rtx call
= XEXP (note
, 0);
4060 /* Find the call insn. */
4061 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
4062 call
= NEXT_INSN (call
);
4064 /* If there is none, do nothing special,
4065 since ordinary death handling can understand these insns. */
4069 /* See if the hard reg holding the value is dead.
4070 If this is a PARALLEL, find the call within it. */
4071 call_pat
= PATTERN (call
);
4072 if (GET_CODE (call_pat
) == PARALLEL
)
4074 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
4075 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
4076 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
4079 /* This may be a library call that is returning a value
4080 via invisible pointer. Do nothing special, since
4081 ordinary death handling can understand these insns. */
4085 call_pat
= XVECEXP (call_pat
, 0, i
);
4088 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
4094 /* Return 1 if register REGNO was used before it was set, i.e. if it is
4095 live at function entry. Don't count global register variables, variables
4096 in registers that can be used for function arg passing, or variables in
4097 fixed hard registers. */
4100 regno_uninitialized (regno
)
4103 if (n_basic_blocks
== 0
4104 || (regno
< FIRST_PSEUDO_REGISTER
4105 && (global_regs
[regno
]
4106 || fixed_regs
[regno
]
4107 || FUNCTION_ARG_REGNO_P (regno
))))
4110 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start
, regno
);
4113 /* 1 if register REGNO was alive at a place where `setjmp' was called
4114 and was set more than once or is an argument.
4115 Such regs may be clobbered by `longjmp'. */
4118 regno_clobbered_at_setjmp (regno
)
4121 if (n_basic_blocks
== 0)
4124 return ((REG_N_SETS (regno
) > 1
4125 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start
, regno
))
4126 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
4129 /* INSN references memory, possibly using autoincrement addressing modes.
4130 Find any entries on the mem_set_list that need to be invalidated due
4131 to an address change. */
4134 invalidate_mems_from_autoinc (pbi
, insn
)
4135 struct propagate_block_info
*pbi
;
4138 rtx note
= REG_NOTES (insn
);
4139 for (note
= REG_NOTES (insn
); note
; note
= XEXP (note
, 1))
4141 if (REG_NOTE_KIND (note
) == REG_INC
)
4143 rtx temp
= pbi
->mem_set_list
;
4144 rtx prev
= NULL_RTX
;
4149 next
= XEXP (temp
, 1);
4150 if (reg_overlap_mentioned_p (XEXP (note
, 0), XEXP (temp
, 0)))
4152 /* Splice temp out of list. */
4154 XEXP (prev
, 1) = next
;
4156 pbi
->mem_set_list
= next
;
4157 free_EXPR_LIST_node (temp
);
4167 /* Process the registers that are set within X. Their bits are set to
4168 1 in the regset DEAD, because they are dead prior to this insn.
4170 If INSN is nonzero, it is the insn being processed.
4172 FLAGS is the set of operations to perform. */
4175 mark_set_regs (pbi
, x
, insn
)
4176 struct propagate_block_info
*pbi
;
4179 rtx cond
= NULL_RTX
;
4184 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
4186 if (REG_NOTE_KIND (link
) == REG_INC
)
4187 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
4188 (GET_CODE (x
) == COND_EXEC
4189 ? COND_EXEC_TEST (x
) : NULL_RTX
),
4193 switch (code
= GET_CODE (x
))
4197 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, pbi
->flags
);
4201 cond
= COND_EXEC_TEST (x
);
4202 x
= COND_EXEC_CODE (x
);
4208 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
4210 rtx sub
= XVECEXP (x
, 0, i
);
4211 switch (code
= GET_CODE (sub
))
4214 if (cond
!= NULL_RTX
)
4217 cond
= COND_EXEC_TEST (sub
);
4218 sub
= COND_EXEC_CODE (sub
);
4219 if (GET_CODE (sub
) != SET
&& GET_CODE (sub
) != CLOBBER
)
4225 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, pbi
->flags
);
4240 /* Process a single SET rtx, X. */
4243 mark_set_1 (pbi
, code
, reg
, cond
, insn
, flags
)
4244 struct propagate_block_info
*pbi
;
4246 rtx reg
, cond
, insn
;
4249 int regno_first
= -1, regno_last
= -1;
4253 /* Some targets place small structures in registers for
4254 return values of functions. We have to detect this
4255 case specially here to get correct flow information. */
4256 if (GET_CODE (reg
) == PARALLEL
4257 && GET_MODE (reg
) == BLKmode
)
4259 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
4260 mark_set_1 (pbi
, code
, XVECEXP (reg
, 0, i
), cond
, insn
, flags
);
4264 /* Modifying just one hardware register of a multi-reg value or just a
4265 byte field of a register does not mean the value from before this insn
4266 is now dead. Of course, if it was dead after it's unused now. */
4268 switch (GET_CODE (reg
))
4272 case STRICT_LOW_PART
:
4273 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
4275 reg
= XEXP (reg
, 0);
4276 while (GET_CODE (reg
) == SUBREG
4277 || GET_CODE (reg
) == ZERO_EXTRACT
4278 || GET_CODE (reg
) == SIGN_EXTRACT
4279 || GET_CODE (reg
) == STRICT_LOW_PART
);
4280 if (GET_CODE (reg
) == MEM
)
4282 not_dead
= REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
4286 regno_last
= regno_first
= REGNO (reg
);
4287 if (regno_first
< FIRST_PSEUDO_REGISTER
)
4288 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
4292 if (GET_CODE (SUBREG_REG (reg
)) == REG
)
4294 enum machine_mode outer_mode
= GET_MODE (reg
);
4295 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
4297 /* Identify the range of registers affected. This is moderately
4298 tricky for hard registers. See alter_subreg. */
4300 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
4301 if (regno_first
< FIRST_PSEUDO_REGISTER
)
4303 #ifdef ALTER_HARD_SUBREG
4304 regno_first
= ALTER_HARD_SUBREG (outer_mode
, SUBREG_WORD (reg
),
4305 inner_mode
, regno_first
);
4307 regno_first
+= SUBREG_WORD (reg
);
4309 regno_last
= (regno_first
4310 + HARD_REGNO_NREGS (regno_first
, outer_mode
) - 1);
4312 /* Since we've just adjusted the register number ranges, make
4313 sure REG matches. Otherwise some_was_live will be clear
4314 when it shouldn't have been, and we'll create incorrect
4315 REG_UNUSED notes. */
4316 reg
= gen_rtx_REG (outer_mode
, regno_first
);
4320 /* If the number of words in the subreg is less than the number
4321 of words in the full register, we have a well-defined partial
4322 set. Otherwise the high bits are undefined.
4324 This is only really applicable to pseudos, since we just took
4325 care of multi-word hard registers. */
4326 if (((GET_MODE_SIZE (outer_mode
)
4327 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
4328 < ((GET_MODE_SIZE (inner_mode
)
4329 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
4330 not_dead
= REGNO_REG_SET_P (pbi
->reg_live
, regno_first
);
4332 reg
= SUBREG_REG (reg
);
4336 reg
= SUBREG_REG (reg
);
4343 /* If this set is a MEM, then it kills any aliased writes.
4344 If this set is a REG, then it kills any MEMs which use the reg. */
4345 if (flags
& PROP_SCAN_DEAD_CODE
)
4347 if (GET_CODE (reg
) == MEM
|| GET_CODE (reg
) == REG
)
4349 rtx temp
= pbi
->mem_set_list
;
4350 rtx prev
= NULL_RTX
;
4355 next
= XEXP (temp
, 1);
4356 if ((GET_CODE (reg
) == MEM
4357 && output_dependence (XEXP (temp
, 0), reg
))
4358 || (GET_CODE (reg
) == REG
4359 && reg_overlap_mentioned_p (reg
, XEXP (temp
, 0))))
4361 /* Splice this entry out of the list. */
4363 XEXP (prev
, 1) = next
;
4365 pbi
->mem_set_list
= next
;
4366 free_EXPR_LIST_node (temp
);
4374 /* If the memory reference had embedded side effects (autoincrement
4375 address modes. Then we may need to kill some entries on the
4377 if (insn
&& GET_CODE (reg
) == MEM
)
4378 invalidate_mems_from_autoinc (pbi
, insn
);
4380 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
4381 /* ??? With more effort we could track conditional memory life. */
4383 /* We do not know the size of a BLKmode store, so we do not track
4384 them for redundant store elimination. */
4385 && GET_MODE (reg
) != BLKmode
4386 /* There are no REG_INC notes for SP, so we can't assume we'll see
4387 everything that invalidates it. To be safe, don't eliminate any
4388 stores though SP; none of them should be redundant anyway. */
4389 && ! reg_mentioned_p (stack_pointer_rtx
, reg
))
4390 pbi
->mem_set_list
= alloc_EXPR_LIST (0, reg
, pbi
->mem_set_list
);
4393 if (GET_CODE (reg
) == REG
4394 && ! (regno_first
== FRAME_POINTER_REGNUM
4395 && (! reload_completed
|| frame_pointer_needed
))
4396 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
4397 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
4398 && (! reload_completed
|| frame_pointer_needed
))
4400 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
4401 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
4405 int some_was_live
= 0, some_was_dead
= 0;
4407 for (i
= regno_first
; i
<= regno_last
; ++i
)
4409 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
4411 SET_REGNO_REG_SET (pbi
->local_set
, i
);
4412 if (code
!= CLOBBER
)
4413 SET_REGNO_REG_SET (pbi
->new_set
, i
);
4415 some_was_live
|= needed_regno
;
4416 some_was_dead
|= ! needed_regno
;
4419 #ifdef HAVE_conditional_execution
4420 /* Consider conditional death in deciding that the register needs
4422 if (some_was_live
&& ! not_dead
4423 /* The stack pointer is never dead. Well, not strictly true,
4424 but it's very difficult to tell from here. Hopefully
4425 combine_stack_adjustments will fix up the most egregious
4427 && regno_first
!= STACK_POINTER_REGNUM
)
4429 for (i
= regno_first
; i
<= regno_last
; ++i
)
4430 if (! mark_regno_cond_dead (pbi
, i
, cond
))
4435 /* Additional data to record if this is the final pass. */
4436 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
4437 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
4440 register int blocknum
= pbi
->bb
->index
;
4443 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
4445 y
= pbi
->reg_next_use
[regno_first
];
4447 /* The next use is no longer next, since a store intervenes. */
4448 for (i
= regno_first
; i
<= regno_last
; ++i
)
4449 pbi
->reg_next_use
[i
] = 0;
4452 if (flags
& PROP_REG_INFO
)
4454 for (i
= regno_first
; i
<= regno_last
; ++i
)
4456 /* Count (weighted) references, stores, etc. This counts a
4457 register twice if it is modified, but that is correct. */
4458 REG_N_SETS (i
) += 1;
4459 REG_N_REFS (i
) += (optimize_size
? 1
4460 : pbi
->bb
->loop_depth
+ 1);
4462 /* The insns where a reg is live are normally counted
4463 elsewhere, but we want the count to include the insn
4464 where the reg is set, and the normal counting mechanism
4465 would not count it. */
4466 REG_LIVE_LENGTH (i
) += 1;
4469 /* If this is a hard reg, record this function uses the reg. */
4470 if (regno_first
< FIRST_PSEUDO_REGISTER
)
4472 for (i
= regno_first
; i
<= regno_last
; i
++)
4473 regs_ever_live
[i
] = 1;
4477 /* Keep track of which basic blocks each reg appears in. */
4478 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
4479 REG_BASIC_BLOCK (regno_first
) = blocknum
;
4480 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
4481 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
4485 if (! some_was_dead
)
4487 if (flags
& PROP_LOG_LINKS
)
4489 /* Make a logical link from the next following insn
4490 that uses this register, back to this insn.
4491 The following insns have already been processed.
4493 We don't build a LOG_LINK for hard registers containing
4494 in ASM_OPERANDs. If these registers get replaced,
4495 we might wind up changing the semantics of the insn,
4496 even if reload can make what appear to be valid
4497 assignments later. */
4498 if (y
&& (BLOCK_NUM (y
) == blocknum
)
4499 && (regno_first
>= FIRST_PSEUDO_REGISTER
4500 || asm_noperands (PATTERN (y
)) < 0))
4501 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
4506 else if (! some_was_live
)
4508 if (flags
& PROP_REG_INFO
)
4509 REG_N_DEATHS (regno_first
) += 1;
4511 if (flags
& PROP_DEATH_NOTES
)
4513 /* Note that dead stores have already been deleted
4514 when possible. If we get here, we have found a
4515 dead store that cannot be eliminated (because the
4516 same insn does something useful). Indicate this
4517 by marking the reg being set as dying here. */
4519 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
4524 if (flags
& PROP_DEATH_NOTES
)
4526 /* This is a case where we have a multi-word hard register
4527 and some, but not all, of the words of the register are
4528 needed in subsequent insns. Write REG_UNUSED notes
4529 for those parts that were not needed. This case should
4532 for (i
= regno_first
; i
<= regno_last
; ++i
)
4533 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
4535 = alloc_EXPR_LIST (REG_UNUSED
,
4536 gen_rtx_REG (reg_raw_mode
[i
], i
),
4542 /* Mark the register as being dead. */
4545 /* The stack pointer is never dead. Well, not strictly true,
4546 but it's very difficult to tell from here. Hopefully
4547 combine_stack_adjustments will fix up the most egregious
4549 && regno_first
!= STACK_POINTER_REGNUM
)
4551 for (i
= regno_first
; i
<= regno_last
; ++i
)
4552 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
4555 else if (GET_CODE (reg
) == REG
)
4557 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
4558 pbi
->reg_next_use
[regno_first
] = 0;
4561 /* If this is the last pass and this is a SCRATCH, show it will be dying
4562 here and count it. */
4563 else if (GET_CODE (reg
) == SCRATCH
)
4565 if (flags
& PROP_DEATH_NOTES
)
4567 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
4571 #ifdef HAVE_conditional_execution
4572 /* Mark REGNO conditionally dead. Return true if the register is
4573 now unconditionally dead. */
4576 mark_regno_cond_dead (pbi
, regno
, cond
)
4577 struct propagate_block_info
*pbi
;
4581 /* If this is a store to a predicate register, the value of the
4582 predicate is changing, we don't know that the predicate as seen
4583 before is the same as that seen after. Flush all dependent
4584 conditions from reg_cond_dead. This will make all such
4585 conditionally live registers unconditionally live. */
4586 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
4587 flush_reg_cond_reg (pbi
, regno
);
4589 /* If this is an unconditional store, remove any conditional
4590 life that may have existed. */
4591 if (cond
== NULL_RTX
)
4592 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
4595 splay_tree_node node
;
4596 struct reg_cond_life_info
*rcli
;
4599 /* Otherwise this is a conditional set. Record that fact.
4600 It may have been conditionally used, or there may be a
4601 subsequent set with a complimentary condition. */
4603 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
4606 /* The register was unconditionally live previously.
4607 Record the current condition as the condition under
4608 which it is dead. */
4609 rcli
= (struct reg_cond_life_info
*)
4610 xmalloc (sizeof (*rcli
));
4611 rcli
->condition
= alloc_EXPR_LIST (0, cond
, NULL_RTX
);
4612 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
4613 (splay_tree_value
) rcli
);
4615 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
4616 REGNO (XEXP (cond
, 0)));
4618 /* Not unconditionaly dead. */
4623 /* The register was conditionally live previously.
4624 Add the new condition to the old. */
4625 rcli
= (struct reg_cond_life_info
*) node
->value
;
4626 ncond
= rcli
->condition
;
4627 ncond
= ior_reg_cond (ncond
, cond
);
4629 /* If the register is now unconditionally dead,
4630 remove the entry in the splay_tree. */
4631 if (ncond
== const1_rtx
)
4632 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
4635 rcli
->condition
= ncond
;
4637 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
4638 REGNO (XEXP (cond
, 0)));
4640 /* Not unconditionaly dead. */
4649 /* Called from splay_tree_delete for pbi->reg_cond_life. */
4652 free_reg_cond_life_info (value
)
4653 splay_tree_value value
;
4655 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
4656 free_EXPR_LIST_list (&rcli
->condition
);
4660 /* Helper function for flush_reg_cond_reg. */
4663 flush_reg_cond_reg_1 (node
, data
)
4664 splay_tree_node node
;
4667 struct reg_cond_life_info
*rcli
;
4668 int *xdata
= (int *) data
;
4669 unsigned int regno
= xdata
[0];
4672 /* Don't need to search if last flushed value was farther on in
4673 the in-order traversal. */
4674 if (xdata
[1] >= (int) node
->key
)
4677 /* Splice out portions of the expression that refer to regno. */
4678 rcli
= (struct reg_cond_life_info
*) node
->value
;
4679 c
= *(prev
= &rcli
->condition
);
4682 if (regno
== REGNO (XEXP (XEXP (c
, 0), 0)))
4684 rtx next
= XEXP (c
, 1);
4685 free_EXPR_LIST_node (c
);
4689 c
= *(prev
= &XEXP (c
, 1));
4692 /* If the entire condition is now NULL, signal the node to be removed. */
4693 if (! rcli
->condition
)
4695 xdata
[1] = node
->key
;
4702 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
4705 flush_reg_cond_reg (pbi
, regno
)
4706 struct propagate_block_info
*pbi
;
4713 while (splay_tree_foreach (pbi
->reg_cond_dead
,
4714 flush_reg_cond_reg_1
, pair
) == -1)
4715 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
4717 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
4720 /* Logical arithmetic on predicate conditions. IOR, NOT and NAND.
4721 We actually use EXPR_LIST to chain the sub-expressions together
4722 instead of IOR because it's easier to manipulate and we have
4723 the lists.c functions to reuse nodes.
4725 Return a new rtl expression as appropriate. */
4728 ior_reg_cond (old
, x
)
4731 enum rtx_code x_code
;
4735 /* We expect these conditions to be of the form (eq reg 0). */
4736 x_code
= GET_CODE (x
);
4737 if (GET_RTX_CLASS (x_code
) != '<'
4738 || GET_CODE (x_reg
= XEXP (x
, 0)) != REG
4739 || XEXP (x
, 1) != const0_rtx
)
4742 /* Search the expression for an existing sub-expression of X_REG. */
4743 for (c
= old
; c
; c
= XEXP (c
, 1))
4745 rtx y
= XEXP (c
, 0);
4746 if (REGNO (XEXP (y
, 0)) == REGNO (x_reg
))
4748 /* If we find X already present in OLD, we need do nothing. */
4749 if (GET_CODE (y
) == x_code
)
4752 /* If we find X being a compliment of a condition in OLD,
4753 then the entire condition is true. */
4754 if (GET_CODE (y
) == reverse_condition (x_code
))
4759 /* Otherwise just add to the chain. */
4760 return alloc_EXPR_LIST (0, x
, old
);
4767 enum rtx_code x_code
;
4770 /* We expect these conditions to be of the form (eq reg 0). */
4771 x_code
= GET_CODE (x
);
4772 if (GET_RTX_CLASS (x_code
) != '<'
4773 || GET_CODE (x_reg
= XEXP (x
, 0)) != REG
4774 || XEXP (x
, 1) != const0_rtx
)
4777 return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code
),
4778 VOIDmode
, x_reg
, const0_rtx
),
4783 nand_reg_cond (old
, x
)
4786 enum rtx_code x_code
;
4790 /* We expect these conditions to be of the form (eq reg 0). */
4791 x_code
= GET_CODE (x
);
4792 if (GET_RTX_CLASS (x_code
) != '<'
4793 || GET_CODE (x_reg
= XEXP (x
, 0)) != REG
4794 || XEXP (x
, 1) != const0_rtx
)
4797 /* Search the expression for an existing sub-expression of X_REG. */
4799 for (c
= *(prev
= &old
); c
; c
= *(prev
= &XEXP (c
, 1)))
4801 rtx y
= XEXP (c
, 0);
4802 if (REGNO (XEXP (y
, 0)) == REGNO (x_reg
))
4804 /* If we find X already present in OLD, then we need to
4806 if (GET_CODE (y
) == x_code
)
4808 *prev
= XEXP (c
, 1);
4809 free_EXPR_LIST_node (c
);
4810 return old
? old
: const0_rtx
;
4813 /* If we find X being a compliment of a condition in OLD,
4814 then we need do nothing. */
4815 if (GET_CODE (y
) == reverse_condition (x_code
))
4820 /* Otherwise, by implication, the register in question is now live for
4821 the inverse of the condition X. */
4822 return alloc_EXPR_LIST (0, gen_rtx_fmt_ee (reverse_condition (x_code
),
4823 VOIDmode
, x_reg
, const0_rtx
),
4826 #endif /* HAVE_conditional_execution */
4830 /* Try to substitute the auto-inc expression INC as the address inside
4831 MEM which occurs in INSN. Currently, the address of MEM is an expression
4832 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
4833 that has a single set whose source is a PLUS of INCR_REG and something
4837 attempt_auto_inc (pbi
, inc
, insn
, mem
, incr
, incr_reg
)
4838 struct propagate_block_info
*pbi
;
4839 rtx inc
, insn
, mem
, incr
, incr_reg
;
4841 int regno
= REGNO (incr_reg
);
4842 rtx set
= single_set (incr
);
4843 rtx q
= SET_DEST (set
);
4844 rtx y
= SET_SRC (set
);
4845 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
4847 /* Make sure this reg appears only once in this insn. */
4848 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
4851 if (dead_or_set_p (incr
, incr_reg
)
4852 /* Mustn't autoinc an eliminable register. */
4853 && (regno
>= FIRST_PSEUDO_REGISTER
4854 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
4856 /* This is the simple case. Try to make the auto-inc. If
4857 we can't, we are done. Otherwise, we will do any
4858 needed updates below. */
4859 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
4862 else if (GET_CODE (q
) == REG
4863 /* PREV_INSN used here to check the semi-open interval
4865 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
4866 /* We must also check for sets of q as q may be
4867 a call clobbered hard register and there may
4868 be a call between PREV_INSN (insn) and incr. */
4869 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
4871 /* We have *p followed sometime later by q = p+size.
4872 Both p and q must be live afterward,
4873 and q is not used between INSN and its assignment.
4874 Change it to q = p, ...*q..., q = q+size.
4875 Then fall into the usual case. */
4880 emit_move_insn (q
, incr_reg
);
4881 insns
= get_insns ();
4884 if (basic_block_for_insn
)
4885 for (temp
= insns
; temp
; temp
= NEXT_INSN (temp
))
4886 set_block_for_insn (temp
, pbi
->bb
);
4888 /* If we can't make the auto-inc, or can't make the
4889 replacement into Y, exit. There's no point in making
4890 the change below if we can't do the auto-inc and doing
4891 so is not correct in the pre-inc case. */
4894 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
4895 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
4896 if (! apply_change_group ())
4899 /* We now know we'll be doing this change, so emit the
4900 new insn(s) and do the updates. */
4901 emit_insns_before (insns
, insn
);
4903 if (pbi
->bb
->head
== insn
)
4904 pbi
->bb
->head
= insns
;
4906 /* INCR will become a NOTE and INSN won't contain a
4907 use of INCR_REG. If a use of INCR_REG was just placed in
4908 the insn before INSN, make that the next use.
4909 Otherwise, invalidate it. */
4910 if (GET_CODE (PREV_INSN (insn
)) == INSN
4911 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
4912 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
4913 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
4915 pbi
->reg_next_use
[regno
] = 0;
4920 /* REGNO is now used in INCR which is below INSN, but
4921 it previously wasn't live here. If we don't mark
4922 it as live, we'll put a REG_DEAD note for it
4923 on this insn, which is incorrect. */
4924 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
4926 /* If there are any calls between INSN and INCR, show
4927 that REGNO now crosses them. */
4928 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
4929 if (GET_CODE (temp
) == CALL_INSN
)
4930 REG_N_CALLS_CROSSED (regno
)++;
4935 /* If we haven't returned, it means we were able to make the
4936 auto-inc, so update the status. First, record that this insn
4937 has an implicit side effect. */
4940 = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
4942 /* Modify the old increment-insn to simply copy
4943 the already-incremented value of our register. */
4944 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
4947 /* If that makes it a no-op (copying the register into itself) delete
4948 it so it won't appear to be a "use" and a "set" of this
4950 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
4952 /* If the original source was dead, it's dead now. */
4955 while (note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
))
4957 remove_note (incr
, note
);
4958 if (XEXP (note
, 0) != incr_reg
)
4959 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
4962 PUT_CODE (incr
, NOTE
);
4963 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
4964 NOTE_SOURCE_FILE (incr
) = 0;
4967 if (regno
>= FIRST_PSEUDO_REGISTER
)
4969 /* Count an extra reference to the reg. When a reg is
4970 incremented, spilling it is worse, so we want to make
4971 that less likely. */
4972 REG_N_REFS (regno
) += (optimize_size
? 1 : pbi
->bb
->loop_depth
+ 1);
4974 /* Count the increment as a setting of the register,
4975 even though it isn't a SET in rtl. */
4976 REG_N_SETS (regno
)++;
4980 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
4984 find_auto_inc (pbi
, x
, insn
)
4985 struct propagate_block_info
*pbi
;
4989 rtx addr
= XEXP (x
, 0);
4990 HOST_WIDE_INT offset
= 0;
4991 rtx set
, y
, incr
, inc_val
;
4993 int size
= GET_MODE_SIZE (GET_MODE (x
));
4995 if (GET_CODE (insn
) == JUMP_INSN
)
4998 /* Here we detect use of an index register which might be good for
4999 postincrement, postdecrement, preincrement, or predecrement. */
5001 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
5002 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
5004 if (GET_CODE (addr
) != REG
)
5007 regno
= REGNO (addr
);
5009 /* Is the next use an increment that might make auto-increment? */
5010 incr
= pbi
->reg_next_use
[regno
];
5011 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
5013 set
= single_set (incr
);
5014 if (set
== 0 || GET_CODE (set
) != SET
)
5018 if (GET_CODE (y
) != PLUS
)
5021 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
5022 inc_val
= XEXP (y
, 1);
5023 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
5024 inc_val
= XEXP (y
, 0);
5028 if (GET_CODE (inc_val
) == CONST_INT
)
5030 if (HAVE_POST_INCREMENT
5031 && (INTVAL (inc_val
) == size
&& offset
== 0))
5032 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
5034 else if (HAVE_POST_DECREMENT
5035 && (INTVAL (inc_val
) == - size
&& offset
== 0))
5036 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
5038 else if (HAVE_PRE_INCREMENT
5039 && (INTVAL (inc_val
) == size
&& offset
== size
))
5040 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
5042 else if (HAVE_PRE_DECREMENT
5043 && (INTVAL (inc_val
) == - size
&& offset
== - size
))
5044 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
5046 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
5047 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
5048 gen_rtx_PLUS (Pmode
,
5051 insn
, x
, incr
, addr
);
5053 else if (GET_CODE (inc_val
) == REG
5054 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
5058 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
5059 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
5060 gen_rtx_PLUS (Pmode
,
5063 insn
, x
, incr
, addr
);
5067 #endif /* AUTO_INC_DEC */
5070 mark_used_reg (pbi
, reg
, cond
, insn
)
5071 struct propagate_block_info
*pbi
;
5073 rtx cond ATTRIBUTE_UNUSED
;
5076 int regno
= REGNO (reg
);
5077 int some_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, regno
);
5078 int some_was_dead
= ! some_was_live
;
5082 /* A hard reg in a wide mode may really be multiple registers.
5083 If so, mark all of them just like the first. */
5084 if (regno
< FIRST_PSEUDO_REGISTER
)
5086 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
5089 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, regno
+ n
);
5090 some_was_live
|= needed_regno
;
5091 some_was_dead
|= ! needed_regno
;
5095 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
5097 /* Record where each reg is used, so when the reg is set we know
5098 the next insn that uses it. */
5099 pbi
->reg_next_use
[regno
] = insn
;
5102 if (pbi
->flags
& PROP_REG_INFO
)
5104 if (regno
< FIRST_PSEUDO_REGISTER
)
5106 /* If this is a register we are going to try to eliminate,
5107 don't mark it live here. If we are successful in
5108 eliminating it, it need not be live unless it is used for
5109 pseudos, in which case it will have been set live when it
5110 was allocated to the pseudos. If the register will not
5111 be eliminated, reload will set it live at that point.
5113 Otherwise, record that this function uses this register. */
5114 /* ??? The PPC backend tries to "eliminate" on the pic
5115 register to itself. This should be fixed. In the mean
5116 time, hack around it. */
5118 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno
)
5119 && (regno
== FRAME_POINTER_REGNUM
5120 || regno
== ARG_POINTER_REGNUM
)))
5122 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
5124 regs_ever_live
[regno
+ --n
] = 1;
5130 /* Keep track of which basic block each reg appears in. */
5132 register int blocknum
= pbi
->bb
->index
;
5133 if (REG_BASIC_BLOCK (regno
) == REG_BLOCK_UNKNOWN
)
5134 REG_BASIC_BLOCK (regno
) = blocknum
;
5135 else if (REG_BASIC_BLOCK (regno
) != blocknum
)
5136 REG_BASIC_BLOCK (regno
) = REG_BLOCK_GLOBAL
;
5138 /* Count (weighted) number of uses of each reg. */
5139 REG_N_REFS (regno
) += (optimize_size
? 1
5140 : pbi
->bb
->loop_depth
+ 1);
5144 /* Find out if any of the register was set this insn. */
5145 some_not_set
= ! REGNO_REG_SET_P (pbi
->new_set
, regno
);
5146 if (regno
< FIRST_PSEUDO_REGISTER
)
5148 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
5150 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, regno
+ n
);
5153 /* Record and count the insns in which a reg dies. If it is used in
5154 this insn and was dead below the insn then it dies in this insn.
5155 If it was set in this insn, we do not make a REG_DEAD note;
5156 likewise if we already made such a note. */
5157 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
5161 /* Check for the case where the register dying partially
5162 overlaps the register set by this insn. */
5163 if (regno
< FIRST_PSEUDO_REGISTER
5164 && HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) > 1)
5166 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
5168 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, regno
+ n
);
5171 /* If none of the words in X is needed, make a REG_DEAD note.
5172 Otherwise, we must make partial REG_DEAD notes. */
5173 if (! some_was_live
)
5175 if ((pbi
->flags
& PROP_DEATH_NOTES
)
5176 && ! find_regno_note (insn
, REG_DEAD
, regno
))
5178 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
5180 if (pbi
->flags
& PROP_REG_INFO
)
5181 REG_N_DEATHS (regno
)++;
5185 /* Don't make a REG_DEAD note for a part of a register
5186 that is set in the insn. */
5188 n
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (reg
)) - 1;
5189 for (; n
>= regno
; n
--)
5190 if (! REGNO_REG_SET_P (pbi
->reg_live
, n
)
5191 && ! dead_or_set_regno_p (insn
, n
))
5193 = alloc_EXPR_LIST (REG_DEAD
,
5194 gen_rtx_REG (reg_raw_mode
[n
], n
),
5199 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
5200 if (regno
< FIRST_PSEUDO_REGISTER
)
5202 n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
5204 SET_REGNO_REG_SET (pbi
->reg_live
, regno
+ n
);
5207 #ifdef HAVE_conditional_execution
5208 /* If this is a conditional use, record that fact. If it is later
5209 conditionally set, we'll know to kill the register. */
5210 if (cond
!= NULL_RTX
)
5212 splay_tree_node node
;
5213 struct reg_cond_life_info
*rcli
;
5218 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
5221 /* The register was unconditionally live previously.
5222 No need to do anything. */
5226 /* The register was conditionally live previously.
5227 Subtract the new life cond from the old death cond. */
5228 rcli
= (struct reg_cond_life_info
*) node
->value
;
5229 ncond
= rcli
->condition
;
5230 ncond
= nand_reg_cond (ncond
, cond
);
5232 /* If the register is now unconditionally live, remove the
5233 entry in the splay_tree. */
5234 if (ncond
== const0_rtx
)
5236 rcli
->condition
= NULL_RTX
;
5237 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
5240 rcli
->condition
= ncond
;
5245 /* The register was not previously live at all. Record
5246 the condition under which it is still dead. */
5247 rcli
= (struct reg_cond_life_info
*) xmalloc (sizeof (*rcli
));
5248 rcli
->condition
= not_reg_cond (cond
);
5249 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
5250 (splay_tree_value
) rcli
);
5253 else if (some_was_live
)
5255 splay_tree_node node
;
5256 struct reg_cond_life_info
*rcli
;
5258 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
5261 /* The register was conditionally live previously, but is now
5262 unconditionally so. Remove it from the conditionally dead
5263 list, so that a conditional set won't cause us to think
5265 rcli
= (struct reg_cond_life_info
*) node
->value
;
5266 rcli
->condition
= NULL_RTX
;
5267 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
5274 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
5275 This is done assuming the registers needed from X are those that
5276 have 1-bits in PBI->REG_LIVE.
5278 INSN is the containing instruction. If INSN is dead, this function
5282 mark_used_regs (pbi
, x
, cond
, insn
)
5283 struct propagate_block_info
*pbi
;
5286 register RTX_CODE code
;
5288 int flags
= pbi
->flags
;
5291 code
= GET_CODE (x
);
5311 /* If we are clobbering a MEM, mark any registers inside the address
5313 if (GET_CODE (XEXP (x
, 0)) == MEM
)
5314 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
5318 /* Don't bother watching stores to mems if this is not the
5319 final pass. We'll not be deleting dead stores this round. */
5320 if (flags
& PROP_SCAN_DEAD_CODE
)
5322 /* Invalidate the data for the last MEM stored, but only if MEM is
5323 something that can be stored into. */
5324 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
5325 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
5326 ; /* needn't clear the memory set list */
5329 rtx temp
= pbi
->mem_set_list
;
5330 rtx prev
= NULL_RTX
;
5335 next
= XEXP (temp
, 1);
5336 if (anti_dependence (XEXP (temp
, 0), x
))
5338 /* Splice temp out of the list. */
5340 XEXP (prev
, 1) = next
;
5342 pbi
->mem_set_list
= next
;
5343 free_EXPR_LIST_node (temp
);
5351 /* If the memory reference had embedded side effects (autoincrement
5352 address modes. Then we may need to kill some entries on the
5355 invalidate_mems_from_autoinc (pbi
, insn
);
5359 if (flags
& PROP_AUTOINC
)
5360 find_auto_inc (pbi
, x
, insn
);
5365 #ifdef CLASS_CANNOT_CHANGE_MODE
5366 if (GET_CODE (SUBREG_REG (x
)) == REG
5367 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
5368 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x
),
5369 GET_MODE (SUBREG_REG (x
))))
5370 REG_CHANGES_MODE (REGNO (SUBREG_REG (x
))) = 1;
5373 /* While we're here, optimize this case. */
5375 if (GET_CODE (x
) != REG
)
5380 /* See a register other than being set => mark it as needed. */
5381 mark_used_reg (pbi
, x
, cond
, insn
);
5386 register rtx testreg
= SET_DEST (x
);
5389 /* If storing into MEM, don't show it as being used. But do
5390 show the address as being used. */
5391 if (GET_CODE (testreg
) == MEM
)
5394 if (flags
& PROP_AUTOINC
)
5395 find_auto_inc (pbi
, testreg
, insn
);
5397 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
5398 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
5402 /* Storing in STRICT_LOW_PART is like storing in a reg
5403 in that this SET might be dead, so ignore it in TESTREG.
5404 but in some other ways it is like using the reg.
5406 Storing in a SUBREG or a bit field is like storing the entire
5407 register in that if the register's value is not used
5408 then this SET is not needed. */
5409 while (GET_CODE (testreg
) == STRICT_LOW_PART
5410 || GET_CODE (testreg
) == ZERO_EXTRACT
5411 || GET_CODE (testreg
) == SIGN_EXTRACT
5412 || GET_CODE (testreg
) == SUBREG
)
5414 #ifdef CLASS_CANNOT_CHANGE_MODE
5415 if (GET_CODE (testreg
) == SUBREG
5416 && GET_CODE (SUBREG_REG (testreg
)) == REG
5417 && REGNO (SUBREG_REG (testreg
)) >= FIRST_PSEUDO_REGISTER
5418 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg
)),
5419 GET_MODE (testreg
)))
5420 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg
))) = 1;
5423 /* Modifying a single register in an alternate mode
5424 does not use any of the old value. But these other
5425 ways of storing in a register do use the old value. */
5426 if (GET_CODE (testreg
) == SUBREG
5427 && !(REG_SIZE (SUBREG_REG (testreg
)) > REG_SIZE (testreg
)))
5432 testreg
= XEXP (testreg
, 0);
5435 /* If this is a store into a register, recursively scan the
5436 value being stored. */
5438 if ((GET_CODE (testreg
) == PARALLEL
5439 && GET_MODE (testreg
) == BLKmode
)
5440 || (GET_CODE (testreg
) == REG
5441 && (regno
= REGNO (testreg
),
5442 ! (regno
== FRAME_POINTER_REGNUM
5443 && (! reload_completed
|| frame_pointer_needed
)))
5444 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
5445 && ! (regno
== HARD_FRAME_POINTER_REGNUM
5446 && (! reload_completed
|| frame_pointer_needed
))
5448 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
5449 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
5454 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
5455 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
5462 case UNSPEC_VOLATILE
:
5466 /* Traditional and volatile asm instructions must be considered to use
5467 and clobber all hard registers, all pseudo-registers and all of
5468 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
5470 Consider for instance a volatile asm that changes the fpu rounding
5471 mode. An insn should not be moved across this even if it only uses
5472 pseudo-regs because it might give an incorrectly rounded result.
5474 ?!? Unfortunately, marking all hard registers as live causes massive
5475 problems for the register allocator and marking all pseudos as live
5476 creates mountains of uninitialized variable warnings.
5478 So for now, just clear the memory set list and mark any regs
5479 we can find in ASM_OPERANDS as used. */
5480 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
5481 free_EXPR_LIST_list (&pbi
->mem_set_list
);
5483 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
5484 We can not just fall through here since then we would be confused
5485 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
5486 traditional asms unlike their normal usage. */
5487 if (code
== ASM_OPERANDS
)
5491 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
5492 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
5498 if (cond
!= NULL_RTX
)
5501 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
5503 cond
= COND_EXEC_TEST (x
);
5504 x
= COND_EXEC_CODE (x
);
5508 /* We _do_not_ want to scan operands of phi nodes. Operands of
5509 a phi function are evaluated only when control reaches this
5510 block along a particular edge. Therefore, regs that appear
5511 as arguments to phi should not be added to the global live at
5519 /* Recursively scan the operands of this expression. */
5522 register const char *fmt
= GET_RTX_FORMAT (code
);
5525 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
5529 /* Tail recursive case: save a function call level. */
5535 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
5537 else if (fmt
[i
] == 'E')
5540 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5541 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
5550 try_pre_increment_1 (pbi
, insn
)
5551 struct propagate_block_info
*pbi
;
5554 /* Find the next use of this reg. If in same basic block,
5555 make it do pre-increment or pre-decrement if appropriate. */
5556 rtx x
= single_set (insn
);
5557 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
5558 * INTVAL (XEXP (SET_SRC (x
), 1)));
5559 int regno
= REGNO (SET_DEST (x
));
5560 rtx y
= pbi
->reg_next_use
[regno
];
5562 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
5563 /* Don't do this if the reg dies, or gets set in y; a standard addressing
5564 mode would be better. */
5565 && ! dead_or_set_p (y
, SET_DEST (x
))
5566 && try_pre_increment (y
, SET_DEST (x
), amount
))
5568 /* We have found a suitable auto-increment
5569 and already changed insn Y to do it.
5570 So flush this increment-instruction. */
5571 PUT_CODE (insn
, NOTE
);
5572 NOTE_LINE_NUMBER (insn
) = NOTE_INSN_DELETED
;
5573 NOTE_SOURCE_FILE (insn
) = 0;
5574 /* Count a reference to this reg for the increment
5575 insn we are deleting. When a reg is incremented.
5576 spilling it is worse, so we want to make that
5578 if (regno
>= FIRST_PSEUDO_REGISTER
)
5580 REG_N_REFS (regno
) += (optimize_size
? 1
5581 : pbi
->bb
->loop_depth
+ 1);
5582 REG_N_SETS (regno
)++;
5589 /* Try to change INSN so that it does pre-increment or pre-decrement
5590 addressing on register REG in order to add AMOUNT to REG.
5591 AMOUNT is negative for pre-decrement.
5592 Returns 1 if the change could be made.
5593 This checks all about the validity of the result of modifying INSN. */
5596 try_pre_increment (insn
, reg
, amount
)
5598 HOST_WIDE_INT amount
;
5602 /* Nonzero if we can try to make a pre-increment or pre-decrement.
5603 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
5605 /* Nonzero if we can try to make a post-increment or post-decrement.
5606 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
5607 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
5608 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
5611 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
5614 /* From the sign of increment, see which possibilities are conceivable
5615 on this target machine. */
5616 if (HAVE_PRE_INCREMENT
&& amount
> 0)
5618 if (HAVE_POST_INCREMENT
&& amount
> 0)
5621 if (HAVE_PRE_DECREMENT
&& amount
< 0)
5623 if (HAVE_POST_DECREMENT
&& amount
< 0)
5626 if (! (pre_ok
|| post_ok
))
5629 /* It is not safe to add a side effect to a jump insn
5630 because if the incremented register is spilled and must be reloaded
5631 there would be no way to store the incremented value back in memory. */
5633 if (GET_CODE (insn
) == JUMP_INSN
)
5638 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
5639 if (post_ok
&& (use
== 0 || use
== (rtx
) 1))
5641 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
5645 if (use
== 0 || use
== (rtx
) 1)
5648 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
5651 /* See if this combination of instruction and addressing mode exists. */
5652 if (! validate_change (insn
, &XEXP (use
, 0),
5653 gen_rtx_fmt_e (amount
> 0
5654 ? (do_post
? POST_INC
: PRE_INC
)
5655 : (do_post
? POST_DEC
: PRE_DEC
),
5659 /* Record that this insn now has an implicit side effect on X. */
5660 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
5664 #endif /* AUTO_INC_DEC */
5666 /* Find the place in the rtx X where REG is used as a memory address.
5667 Return the MEM rtx that so uses it.
5668 If PLUSCONST is nonzero, search instead for a memory address equivalent to
5669 (plus REG (const_int PLUSCONST)).
5671 If such an address does not appear, return 0.
5672 If REG appears more than once, or is used other than in such an address,
5676 find_use_as_address (x
, reg
, plusconst
)
5679 HOST_WIDE_INT plusconst
;
5681 enum rtx_code code
= GET_CODE (x
);
5682 const char *fmt
= GET_RTX_FORMAT (code
);
5684 register rtx value
= 0;
5687 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
5690 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
5691 && XEXP (XEXP (x
, 0), 0) == reg
5692 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
5693 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
5696 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
5698 /* If REG occurs inside a MEM used in a bit-field reference,
5699 that is unacceptable. */
5700 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
5701 return (rtx
) (HOST_WIDE_INT
) 1;
5705 return (rtx
) (HOST_WIDE_INT
) 1;
5707 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
5711 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
5715 return (rtx
) (HOST_WIDE_INT
) 1;
5717 else if (fmt
[i
] == 'E')
5720 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5722 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
5726 return (rtx
) (HOST_WIDE_INT
) 1;
5734 /* Write information about registers and basic blocks into FILE.
5735 This is part of making a debugging dump. */
5738 dump_regset (r
, outf
)
5745 fputs (" (nil)", outf
);
5749 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
5751 fprintf (outf
, " %d", i
);
5752 if (i
< FIRST_PSEUDO_REGISTER
)
5753 fprintf (outf
, " [%s]",
5762 dump_regset (r
, stderr
);
5763 putc ('\n', stderr
);
5767 dump_flow_info (file
)
5771 static const char * const reg_class_names
[] = REG_CLASS_NAMES
;
5773 fprintf (file
, "%d registers.\n", max_regno
);
5774 for (i
= FIRST_PSEUDO_REGISTER
; i
< max_regno
; i
++)
5777 enum reg_class
class, altclass
;
5778 fprintf (file
, "\nRegister %d used %d times across %d insns",
5779 i
, REG_N_REFS (i
), REG_LIVE_LENGTH (i
));
5780 if (REG_BASIC_BLOCK (i
) >= 0)
5781 fprintf (file
, " in block %d", REG_BASIC_BLOCK (i
));
5783 fprintf (file
, "; set %d time%s", REG_N_SETS (i
),
5784 (REG_N_SETS (i
) == 1) ? "" : "s");
5785 if (REG_USERVAR_P (regno_reg_rtx
[i
]))
5786 fprintf (file
, "; user var");
5787 if (REG_N_DEATHS (i
) != 1)
5788 fprintf (file
, "; dies in %d places", REG_N_DEATHS (i
));
5789 if (REG_N_CALLS_CROSSED (i
) == 1)
5790 fprintf (file
, "; crosses 1 call");
5791 else if (REG_N_CALLS_CROSSED (i
))
5792 fprintf (file
, "; crosses %d calls", REG_N_CALLS_CROSSED (i
));
5793 if (PSEUDO_REGNO_BYTES (i
) != UNITS_PER_WORD
)
5794 fprintf (file
, "; %d bytes", PSEUDO_REGNO_BYTES (i
));
5795 class = reg_preferred_class (i
);
5796 altclass
= reg_alternate_class (i
);
5797 if (class != GENERAL_REGS
|| altclass
!= ALL_REGS
)
5799 if (altclass
== ALL_REGS
|| class == ALL_REGS
)
5800 fprintf (file
, "; pref %s", reg_class_names
[(int) class]);
5801 else if (altclass
== NO_REGS
)
5802 fprintf (file
, "; %s or none", reg_class_names
[(int) class]);
5804 fprintf (file
, "; pref %s, else %s",
5805 reg_class_names
[(int) class],
5806 reg_class_names
[(int) altclass
]);
5808 if (REGNO_POINTER_FLAG (i
))
5809 fprintf (file
, "; pointer");
5810 fprintf (file
, ".\n");
5813 fprintf (file
, "\n%d basic blocks, %d edges.\n", n_basic_blocks
, n_edges
);
5814 for (i
= 0; i
< n_basic_blocks
; i
++)
5816 register basic_block bb
= BASIC_BLOCK (i
);
5819 fprintf (file
, "\nBasic block %d: first insn %d, last %d, loop_depth %d, count %d.\n",
5820 i
, INSN_UID (bb
->head
), INSN_UID (bb
->end
), bb
->loop_depth
, bb
->count
);
5822 fprintf (file
, "Predecessors: ");
5823 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
5824 dump_edge_info (file
, e
, 0);
5826 fprintf (file
, "\nSuccessors: ");
5827 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
5828 dump_edge_info (file
, e
, 1);
5830 fprintf (file
, "\nRegisters live at start:");
5831 dump_regset (bb
->global_live_at_start
, file
);
5833 fprintf (file
, "\nRegisters live at end:");
5834 dump_regset (bb
->global_live_at_end
, file
);
5845 dump_flow_info (stderr
);
5849 dump_edge_info (file
, e
, do_succ
)
5854 basic_block side
= (do_succ
? e
->dest
: e
->src
);
5856 if (side
== ENTRY_BLOCK_PTR
)
5857 fputs (" ENTRY", file
);
5858 else if (side
== EXIT_BLOCK_PTR
)
5859 fputs (" EXIT", file
);
5861 fprintf (file
, " %d", side
->index
);
5864 fprintf (file
, " count:%d", e
->count
);
5868 static const char * const bitnames
[] = {
5869 "fallthru", "crit", "ab", "abcall", "eh", "fake"
5872 int i
, flags
= e
->flags
;
5876 for (i
= 0; flags
; i
++)
5877 if (flags
& (1 << i
))
5883 if (i
< (int)(sizeof (bitnames
) / sizeof (*bitnames
)))
5884 fputs (bitnames
[i
], file
);
5886 fprintf (file
, "%d", i
);
5894 /* Print out one basic block with live information at start and end. */
5904 fprintf (outf
, ";; Basic block %d, loop depth %d, count %d",
5905 bb
->index
, bb
->loop_depth
, bb
->count
);
5906 if (bb
->eh_beg
!= -1 || bb
->eh_end
!= -1)
5907 fprintf (outf
, ", eh regions %d/%d", bb
->eh_beg
, bb
->eh_end
);
5910 fputs (";; Predecessors: ", outf
);
5911 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
5912 dump_edge_info (outf
, e
, 0);
5915 fputs (";; Registers live at start:", outf
);
5916 dump_regset (bb
->global_live_at_start
, outf
);
5919 for (insn
= bb
->head
, last
= NEXT_INSN (bb
->end
);
5921 insn
= NEXT_INSN (insn
))
5922 print_rtl_single (outf
, insn
);
5924 fputs (";; Registers live at end:", outf
);
5925 dump_regset (bb
->global_live_at_end
, outf
);
5928 fputs (";; Successors: ", outf
);
5929 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
5930 dump_edge_info (outf
, e
, 1);
5938 dump_bb (bb
, stderr
);
5945 dump_bb (BASIC_BLOCK(n
), stderr
);
5948 /* Like print_rtl, but also print out live information for the start of each
5952 print_rtl_with_bb (outf
, rtx_first
)
5956 register rtx tmp_rtx
;
5959 fprintf (outf
, "(nil)\n");
5963 enum bb_state
{ NOT_IN_BB
, IN_ONE_BB
, IN_MULTIPLE_BB
};
5964 int max_uid
= get_max_uid ();
5965 basic_block
*start
= (basic_block
*)
5966 xcalloc (max_uid
, sizeof (basic_block
));
5967 basic_block
*end
= (basic_block
*)
5968 xcalloc (max_uid
, sizeof (basic_block
));
5969 enum bb_state
*in_bb_p
= (enum bb_state
*)
5970 xcalloc (max_uid
, sizeof (enum bb_state
));
5972 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
5974 basic_block bb
= BASIC_BLOCK (i
);
5977 start
[INSN_UID (bb
->head
)] = bb
;
5978 end
[INSN_UID (bb
->end
)] = bb
;
5979 for (x
= bb
->head
; x
!= NULL_RTX
; x
= NEXT_INSN (x
))
5981 enum bb_state state
= IN_MULTIPLE_BB
;
5982 if (in_bb_p
[INSN_UID(x
)] == NOT_IN_BB
)
5984 in_bb_p
[INSN_UID(x
)] = state
;
5991 for (tmp_rtx
= rtx_first
; NULL
!= tmp_rtx
; tmp_rtx
= NEXT_INSN (tmp_rtx
))
5996 if ((bb
= start
[INSN_UID (tmp_rtx
)]) != NULL
)
5998 fprintf (outf
, ";; Start of basic block %d, registers live:",
6000 dump_regset (bb
->global_live_at_start
, outf
);
6004 if (in_bb_p
[INSN_UID(tmp_rtx
)] == NOT_IN_BB
6005 && GET_CODE (tmp_rtx
) != NOTE
6006 && GET_CODE (tmp_rtx
) != BARRIER
)
6007 fprintf (outf
, ";; Insn is not within a basic block\n");
6008 else if (in_bb_p
[INSN_UID(tmp_rtx
)] == IN_MULTIPLE_BB
)
6009 fprintf (outf
, ";; Insn is in multiple basic blocks\n");
6011 did_output
= print_rtl_single (outf
, tmp_rtx
);
6013 if ((bb
= end
[INSN_UID (tmp_rtx
)]) != NULL
)
6015 fprintf (outf
, ";; End of basic block %d, registers live:\n",
6017 dump_regset (bb
->global_live_at_end
, outf
);
6030 if (current_function_epilogue_delay_list
!= 0)
6032 fprintf (outf
, "\n;; Insns in epilogue delay list:\n\n");
6033 for (tmp_rtx
= current_function_epilogue_delay_list
; tmp_rtx
!= 0;
6034 tmp_rtx
= XEXP (tmp_rtx
, 1))
6035 print_rtl_single (outf
, XEXP (tmp_rtx
, 0));
6039 /* Compute dominator relationships using new flow graph structures. */
6041 compute_flow_dominators (dominators
, post_dominators
)
6042 sbitmap
*dominators
;
6043 sbitmap
*post_dominators
;
6046 sbitmap
*temp_bitmap
;
6048 basic_block
*worklist
, *workend
, *qin
, *qout
;
6051 /* Allocate a worklist array/queue. Entries are only added to the
6052 list if they were not already on the list. So the size is
6053 bounded by the number of basic blocks. */
6054 worklist
= (basic_block
*) xmalloc (sizeof (basic_block
) * n_basic_blocks
);
6055 workend
= &worklist
[n_basic_blocks
];
6057 temp_bitmap
= sbitmap_vector_alloc (n_basic_blocks
, n_basic_blocks
);
6058 sbitmap_vector_zero (temp_bitmap
, n_basic_blocks
);
6062 /* The optimistic setting of dominators requires us to put every
6063 block on the work list initially. */
6064 qin
= qout
= worklist
;
6065 for (bb
= 0; bb
< n_basic_blocks
; bb
++)
6067 *qin
++ = BASIC_BLOCK (bb
);
6068 BASIC_BLOCK (bb
)->aux
= BASIC_BLOCK (bb
);
6070 qlen
= n_basic_blocks
;
6073 /* We want a maximal solution, so initially assume everything dominates
6075 sbitmap_vector_ones (dominators
, n_basic_blocks
);
6077 /* Mark successors of the entry block so we can identify them below. */
6078 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
6079 e
->dest
->aux
= ENTRY_BLOCK_PTR
;
6081 /* Iterate until the worklist is empty. */
6084 /* Take the first entry off the worklist. */
6085 basic_block b
= *qout
++;
6086 if (qout
>= workend
)
6092 /* Compute the intersection of the dominators of all the
6095 If one of the predecessor blocks is the ENTRY block, then the
6096 intersection of the dominators of the predecessor blocks is
6097 defined as the null set. We can identify such blocks by the
6098 special value in the AUX field in the block structure. */
6099 if (b
->aux
== ENTRY_BLOCK_PTR
)
6101 /* Do not clear the aux field for blocks which are
6102 successors of the ENTRY block. That way we we never
6103 add them to the worklist again.
6105 The intersect of dominators of the preds of this block is
6106 defined as the null set. */
6107 sbitmap_zero (temp_bitmap
[bb
]);
6111 /* Clear the aux field of this block so it can be added to
6112 the worklist again if necessary. */
6114 sbitmap_intersection_of_preds (temp_bitmap
[bb
], dominators
, bb
);
6117 /* Make sure each block always dominates itself. */
6118 SET_BIT (temp_bitmap
[bb
], bb
);
6120 /* If the out state of this block changed, then we need to
6121 add the successors of this block to the worklist if they
6122 are not already on the worklist. */
6123 if (sbitmap_a_and_b (dominators
[bb
], dominators
[bb
], temp_bitmap
[bb
]))
6125 for (e
= b
->succ
; e
; e
= e
->succ_next
)
6127 if (!e
->dest
->aux
&& e
->dest
!= EXIT_BLOCK_PTR
)
6141 if (post_dominators
)
6143 /* The optimistic setting of dominators requires us to put every
6144 block on the work list initially. */
6145 qin
= qout
= worklist
;
6146 for (bb
= 0; bb
< n_basic_blocks
; bb
++)
6148 *qin
++ = BASIC_BLOCK (bb
);
6149 BASIC_BLOCK (bb
)->aux
= BASIC_BLOCK (bb
);
6151 qlen
= n_basic_blocks
;
6154 /* We want a maximal solution, so initially assume everything post
6155 dominates everything else. */
6156 sbitmap_vector_ones (post_dominators
, n_basic_blocks
);
6158 /* Mark predecessors of the exit block so we can identify them below. */
6159 for (e
= EXIT_BLOCK_PTR
->pred
; e
; e
= e
->pred_next
)
6160 e
->src
->aux
= EXIT_BLOCK_PTR
;
6162 /* Iterate until the worklist is empty. */
6165 /* Take the first entry off the worklist. */
6166 basic_block b
= *qout
++;
6167 if (qout
>= workend
)
6173 /* Compute the intersection of the post dominators of all the
6176 If one of the successor blocks is the EXIT block, then the
6177 intersection of the dominators of the successor blocks is
6178 defined as the null set. We can identify such blocks by the
6179 special value in the AUX field in the block structure. */
6180 if (b
->aux
== EXIT_BLOCK_PTR
)
6182 /* Do not clear the aux field for blocks which are
6183 predecessors of the EXIT block. That way we we never
6184 add them to the worklist again.
6186 The intersect of dominators of the succs of this block is
6187 defined as the null set. */
6188 sbitmap_zero (temp_bitmap
[bb
]);
6192 /* Clear the aux field of this block so it can be added to
6193 the worklist again if necessary. */
6195 sbitmap_intersection_of_succs (temp_bitmap
[bb
],
6196 post_dominators
, bb
);
6199 /* Make sure each block always post dominates itself. */
6200 SET_BIT (temp_bitmap
[bb
], bb
);
6202 /* If the out state of this block changed, then we need to
6203 add the successors of this block to the worklist if they
6204 are not already on the worklist. */
6205 if (sbitmap_a_and_b (post_dominators
[bb
],
6206 post_dominators
[bb
],
6209 for (e
= b
->pred
; e
; e
= e
->pred_next
)
6211 if (!e
->src
->aux
&& e
->src
!= ENTRY_BLOCK_PTR
)
6229 /* Given DOMINATORS, compute the immediate dominators into IDOM. If a
6230 block dominates only itself, its entry remains as INVALID_BLOCK. */
6233 compute_immediate_dominators (idom
, dominators
)
6235 sbitmap
*dominators
;
6240 tmp
= sbitmap_vector_alloc (n_basic_blocks
, n_basic_blocks
);
6242 /* Begin with tmp(n) = dom(n) - { n }. */
6243 for (b
= n_basic_blocks
; --b
>= 0; )
6245 sbitmap_copy (tmp
[b
], dominators
[b
]);
6246 RESET_BIT (tmp
[b
], b
);
6249 /* Subtract out all of our dominator's dominators. */
6250 for (b
= n_basic_blocks
; --b
>= 0; )
6252 sbitmap tmp_b
= tmp
[b
];
6255 for (s
= n_basic_blocks
; --s
>= 0; )
6256 if (TEST_BIT (tmp_b
, s
))
6257 sbitmap_difference (tmp_b
, tmp_b
, tmp
[s
]);
6260 /* Find the one bit set in the bitmap and put it in the output array. */
6261 for (b
= n_basic_blocks
; --b
>= 0; )
6264 EXECUTE_IF_SET_IN_SBITMAP (tmp
[b
], 0, t
, { idom
[b
] = t
; });
6267 sbitmap_vector_free (tmp
);
6270 /* Given POSTDOMINATORS, compute the immediate postdominators into
6271 IDOM. If a block is only dominated by itself, its entry remains as
6275 compute_immediate_postdominators (idom
, postdominators
)
6277 sbitmap
*postdominators
;
6279 compute_immediate_dominators (idom
, postdominators
);
6282 /* Recompute register set/reference counts immediately prior to register
6285 This avoids problems with set/reference counts changing to/from values
6286 which have special meanings to the register allocators.
6288 Additionally, the reference counts are the primary component used by the
6289 register allocators to prioritize pseudos for allocation to hard regs.
6290 More accurate reference counts generally lead to better register allocation.
6292 F is the first insn to be scanned.
6294 LOOP_STEP denotes how much loop_depth should be incremented per
6295 loop nesting level in order to increase the ref count more for
6296 references in a loop.
6298 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
6299 possibly other information which is used by the register allocators. */
6302 recompute_reg_usage (f
, loop_step
)
6303 rtx f ATTRIBUTE_UNUSED
;
6304 int loop_step ATTRIBUTE_UNUSED
;
6306 allocate_reg_life_data ();
6307 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
);
6310 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
6311 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
6312 of the number of registers that died. */
6315 count_or_remove_death_notes (blocks
, kill
)
6321 for (i
= n_basic_blocks
- 1; i
>= 0; --i
)
6326 if (blocks
&& ! TEST_BIT (blocks
, i
))
6329 bb
= BASIC_BLOCK (i
);
6331 for (insn
= bb
->head
; ; insn
= NEXT_INSN (insn
))
6335 rtx
*pprev
= ®_NOTES (insn
);
6340 switch (REG_NOTE_KIND (link
))
6343 if (GET_CODE (XEXP (link
, 0)) == REG
)
6345 rtx reg
= XEXP (link
, 0);
6348 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
6351 n
= HARD_REGNO_NREGS (REGNO (reg
), GET_MODE (reg
));
6359 rtx next
= XEXP (link
, 1);
6360 free_EXPR_LIST_node (link
);
6361 *pprev
= link
= next
;
6367 pprev
= &XEXP (link
, 1);
6374 if (insn
== bb
->end
)
6382 /* Record INSN's block as BB. */
6385 set_block_for_insn (insn
, bb
)
6389 size_t uid
= INSN_UID (insn
);
6390 if (uid
>= basic_block_for_insn
->num_elements
)
6394 /* Add one-eighth the size so we don't keep calling xrealloc. */
6395 new_size
= uid
+ (uid
+ 7) / 8;
6397 VARRAY_GROW (basic_block_for_insn
, new_size
);
6399 VARRAY_BB (basic_block_for_insn
, uid
) = bb
;
6402 /* Record INSN's block number as BB. */
6403 /* ??? This has got to go. */
6406 set_block_num (insn
, bb
)
6410 set_block_for_insn (insn
, BASIC_BLOCK (bb
));
6413 /* Verify the CFG consistency. This function check some CFG invariants and
6414 aborts when something is wrong. Hope that this function will help to
6415 convert many optimization passes to preserve CFG consistent.
6417 Currently it does following checks:
6419 - test head/end pointers
6420 - overlapping of basic blocks
6421 - edge list corectness
6422 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
6423 - tails of basic blocks (ensure that boundary is necesary)
6424 - scans body of the basic block for JUMP_INSN, CODE_LABEL
6425 and NOTE_INSN_BASIC_BLOCK
6426 - check that all insns are in the basic blocks
6427 (except the switch handling code, barriers and notes)
6428 - check that all returns are followed by barriers
6430 In future it can be extended check a lot of other stuff as well
6431 (reachability of basic blocks, life information, etc. etc.). */
6436 const int max_uid
= get_max_uid ();
6437 const rtx rtx_first
= get_insns ();
6438 rtx last_head
= get_last_insn ();
6439 basic_block
*bb_info
;
6441 int i
, last_bb_num_seen
, num_bb_notes
, err
= 0;
6443 bb_info
= (basic_block
*) xcalloc (max_uid
, sizeof (basic_block
));
6445 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
6447 basic_block bb
= BASIC_BLOCK (i
);
6448 rtx head
= bb
->head
;
6451 /* Verify the end of the basic block is in the INSN chain. */
6452 for (x
= last_head
; x
!= NULL_RTX
; x
= PREV_INSN (x
))
6457 error ("End insn %d for block %d not found in the insn stream.",
6458 INSN_UID (end
), bb
->index
);
6462 /* Work backwards from the end to the head of the basic block
6463 to verify the head is in the RTL chain. */
6464 for ( ; x
!= NULL_RTX
; x
= PREV_INSN (x
))
6466 /* While walking over the insn chain, verify insns appear
6467 in only one basic block and initialize the BB_INFO array
6468 used by other passes. */
6469 if (bb_info
[INSN_UID (x
)] != NULL
)
6471 error ("Insn %d is in multiple basic blocks (%d and %d)",
6472 INSN_UID (x
), bb
->index
, bb_info
[INSN_UID (x
)]->index
);
6475 bb_info
[INSN_UID (x
)] = bb
;
6482 error ("Head insn %d for block %d not found in the insn stream.",
6483 INSN_UID (head
), bb
->index
);
6490 /* Now check the basic blocks (boundaries etc.) */
6491 for (i
= n_basic_blocks
- 1; i
>= 0; i
--)
6493 basic_block bb
= BASIC_BLOCK (i
);
6494 /* Check corectness of edge lists */
6502 fprintf (stderr
, "verify_flow_info: Basic block %d succ edge is corrupted\n",
6504 fprintf (stderr
, "Predecessor: ");
6505 dump_edge_info (stderr
, e
, 0);
6506 fprintf (stderr
, "\nSuccessor: ");
6507 dump_edge_info (stderr
, e
, 1);
6511 if (e
->dest
!= EXIT_BLOCK_PTR
)
6513 edge e2
= e
->dest
->pred
;
6514 while (e2
&& e2
!= e
)
6518 error ("Basic block %i edge lists are corrupted", bb
->index
);
6530 error ("Basic block %d pred edge is corrupted", bb
->index
);
6531 fputs ("Predecessor: ", stderr
);
6532 dump_edge_info (stderr
, e
, 0);
6533 fputs ("\nSuccessor: ", stderr
);
6534 dump_edge_info (stderr
, e
, 1);
6535 fputc ('\n', stderr
);
6538 if (e
->src
!= ENTRY_BLOCK_PTR
)
6540 edge e2
= e
->src
->succ
;
6541 while (e2
&& e2
!= e
)
6545 error ("Basic block %i edge lists are corrupted", bb
->index
);
6552 /* OK pointers are correct. Now check the header of basic
6553 block. It ought to contain optional CODE_LABEL followed
6554 by NOTE_BASIC_BLOCK. */
6556 if (GET_CODE (x
) == CODE_LABEL
)
6560 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
6566 if (!NOTE_INSN_BASIC_BLOCK_P (x
) || NOTE_BASIC_BLOCK (x
) != bb
)
6568 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d\n",
6575 /* Do checks for empty blocks here */
6582 if (NOTE_INSN_BASIC_BLOCK_P (x
))
6584 error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d",
6585 INSN_UID (x
), bb
->index
);
6592 if (GET_CODE (x
) == JUMP_INSN
6593 || GET_CODE (x
) == CODE_LABEL
6594 || GET_CODE (x
) == BARRIER
)
6596 error ("In basic block %d:", bb
->index
);
6597 fatal_insn ("Flow control insn inside a basic block", x
);
6605 last_bb_num_seen
= -1;
6610 if (NOTE_INSN_BASIC_BLOCK_P (x
))
6612 basic_block bb
= NOTE_BASIC_BLOCK (x
);
6614 if (bb
->index
!= last_bb_num_seen
+ 1)
6615 fatal ("Basic blocks not numbered consecutively");
6616 last_bb_num_seen
= bb
->index
;
6619 if (!bb_info
[INSN_UID (x
)])
6621 switch (GET_CODE (x
))
6628 /* An addr_vec is placed outside any block block. */
6630 && GET_CODE (NEXT_INSN (x
)) == JUMP_INSN
6631 && (GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_DIFF_VEC
6632 || GET_CODE (PATTERN (NEXT_INSN (x
))) == ADDR_VEC
))
6637 /* But in any case, non-deletable labels can appear anywhere. */
6641 fatal_insn ("Insn outside basic block", x
);
6646 && GET_CODE (x
) == JUMP_INSN
6647 && returnjump_p (x
) && ! condjump_p (x
)
6648 && ! (NEXT_INSN (x
) && GET_CODE (NEXT_INSN (x
)) == BARRIER
))
6649 fatal_insn ("Return not followed by barrier", x
);
6654 if (num_bb_notes
!= n_basic_blocks
)
6655 fatal ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
6656 num_bb_notes
, n_basic_blocks
);
6665 /* Functions to access an edge list with a vector representation.
6666 Enough data is kept such that given an index number, the
6667 pred and succ that edge represents can be determined, or
6668 given a pred and a succ, its index number can be returned.
6669 This allows algorithms which consume a lot of memory to
6670 represent the normally full matrix of edge (pred,succ) with a
6671 single indexed vector, edge (EDGE_INDEX (pred, succ)), with no
6672 wasted space in the client code due to sparse flow graphs. */
6674 /* This functions initializes the edge list. Basically the entire
6675 flowgraph is processed, and all edges are assigned a number,
6676 and the data structure is filled in. */
6680 struct edge_list
*elist
;
6686 block_count
= n_basic_blocks
+ 2; /* Include the entry and exit blocks. */
6690 /* Determine the number of edges in the flow graph by counting successor
6691 edges on each basic block. */
6692 for (x
= 0; x
< n_basic_blocks
; x
++)
6694 basic_block bb
= BASIC_BLOCK (x
);
6696 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
6699 /* Don't forget successors of the entry block. */
6700 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
6703 elist
= (struct edge_list
*) xmalloc (sizeof (struct edge_list
));
6704 elist
->num_blocks
= block_count
;
6705 elist
->num_edges
= num_edges
;
6706 elist
->index_to_edge
= (edge
*) xmalloc (sizeof (edge
) * num_edges
);
6710 /* Follow successors of the entry block, and register these edges. */
6711 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
6713 elist
->index_to_edge
[num_edges
] = e
;
6717 for (x
= 0; x
< n_basic_blocks
; x
++)
6719 basic_block bb
= BASIC_BLOCK (x
);
6721 /* Follow all successors of blocks, and register these edges. */
6722 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
6724 elist
->index_to_edge
[num_edges
] = e
;
6731 /* This function free's memory associated with an edge list. */
6733 free_edge_list (elist
)
6734 struct edge_list
*elist
;
6738 free (elist
->index_to_edge
);
6743 /* This function provides debug output showing an edge list. */
6745 print_edge_list (f
, elist
)
6747 struct edge_list
*elist
;
6750 fprintf(f
, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
6751 elist
->num_blocks
- 2, elist
->num_edges
);
6753 for (x
= 0; x
< elist
->num_edges
; x
++)
6755 fprintf (f
, " %-4d - edge(", x
);
6756 if (INDEX_EDGE_PRED_BB (elist
, x
) == ENTRY_BLOCK_PTR
)
6757 fprintf (f
,"entry,");
6759 fprintf (f
,"%d,", INDEX_EDGE_PRED_BB (elist
, x
)->index
);
6761 if (INDEX_EDGE_SUCC_BB (elist
, x
) == EXIT_BLOCK_PTR
)
6762 fprintf (f
,"exit)\n");
6764 fprintf (f
,"%d)\n", INDEX_EDGE_SUCC_BB (elist
, x
)->index
);
6768 /* This function provides an internal consistency check of an edge list,
6769 verifying that all edges are present, and that there are no
6772 verify_edge_list (f
, elist
)
6774 struct edge_list
*elist
;
6776 int x
, pred
, succ
, index
;
6779 for (x
= 0; x
< n_basic_blocks
; x
++)
6781 basic_block bb
= BASIC_BLOCK (x
);
6783 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
6785 pred
= e
->src
->index
;
6786 succ
= e
->dest
->index
;
6787 index
= EDGE_INDEX (elist
, e
->src
, e
->dest
);
6788 if (index
== EDGE_INDEX_NO_EDGE
)
6790 fprintf (f
, "*p* No index for edge from %d to %d\n",pred
, succ
);
6793 if (INDEX_EDGE_PRED_BB (elist
, index
)->index
!= pred
)
6794 fprintf (f
, "*p* Pred for index %d should be %d not %d\n",
6795 index
, pred
, INDEX_EDGE_PRED_BB (elist
, index
)->index
);
6796 if (INDEX_EDGE_SUCC_BB (elist
, index
)->index
!= succ
)
6797 fprintf (f
, "*p* Succ for index %d should be %d not %d\n",
6798 index
, succ
, INDEX_EDGE_SUCC_BB (elist
, index
)->index
);
6801 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
6803 pred
= e
->src
->index
;
6804 succ
= e
->dest
->index
;
6805 index
= EDGE_INDEX (elist
, e
->src
, e
->dest
);
6806 if (index
== EDGE_INDEX_NO_EDGE
)
6808 fprintf (f
, "*p* No index for edge from %d to %d\n",pred
, succ
);
6811 if (INDEX_EDGE_PRED_BB (elist
, index
)->index
!= pred
)
6812 fprintf (f
, "*p* Pred for index %d should be %d not %d\n",
6813 index
, pred
, INDEX_EDGE_PRED_BB (elist
, index
)->index
);
6814 if (INDEX_EDGE_SUCC_BB (elist
, index
)->index
!= succ
)
6815 fprintf (f
, "*p* Succ for index %d should be %d not %d\n",
6816 index
, succ
, INDEX_EDGE_SUCC_BB (elist
, index
)->index
);
6818 /* We've verified that all the edges are in the list, no lets make sure
6819 there are no spurious edges in the list. */
6821 for (pred
= 0 ; pred
< n_basic_blocks
; pred
++)
6822 for (succ
= 0 ; succ
< n_basic_blocks
; succ
++)
6824 basic_block p
= BASIC_BLOCK (pred
);
6825 basic_block s
= BASIC_BLOCK (succ
);
6829 for (e
= p
->succ
; e
; e
= e
->succ_next
)
6835 for (e
= s
->pred
; e
; e
= e
->pred_next
)
6841 if (EDGE_INDEX (elist
, BASIC_BLOCK (pred
), BASIC_BLOCK (succ
))
6842 == EDGE_INDEX_NO_EDGE
&& found_edge
!= 0)
6843 fprintf (f
, "*** Edge (%d, %d) appears to not have an index\n",
6845 if (EDGE_INDEX (elist
, BASIC_BLOCK (pred
), BASIC_BLOCK (succ
))
6846 != EDGE_INDEX_NO_EDGE
&& found_edge
== 0)
6847 fprintf (f
, "*** Edge (%d, %d) has index %d, but there is no edge\n",
6848 pred
, succ
, EDGE_INDEX (elist
, BASIC_BLOCK (pred
),
6849 BASIC_BLOCK (succ
)));
6851 for (succ
= 0 ; succ
< n_basic_blocks
; succ
++)
6853 basic_block p
= ENTRY_BLOCK_PTR
;
6854 basic_block s
= BASIC_BLOCK (succ
);
6858 for (e
= p
->succ
; e
; e
= e
->succ_next
)
6864 for (e
= s
->pred
; e
; e
= e
->pred_next
)
6870 if (EDGE_INDEX (elist
, ENTRY_BLOCK_PTR
, BASIC_BLOCK (succ
))
6871 == EDGE_INDEX_NO_EDGE
&& found_edge
!= 0)
6872 fprintf (f
, "*** Edge (entry, %d) appears to not have an index\n",
6874 if (EDGE_INDEX (elist
, ENTRY_BLOCK_PTR
, BASIC_BLOCK (succ
))
6875 != EDGE_INDEX_NO_EDGE
&& found_edge
== 0)
6876 fprintf (f
, "*** Edge (entry, %d) has index %d, but no edge exists\n",
6877 succ
, EDGE_INDEX (elist
, ENTRY_BLOCK_PTR
,
6878 BASIC_BLOCK (succ
)));
6880 for (pred
= 0 ; pred
< n_basic_blocks
; pred
++)
6882 basic_block p
= BASIC_BLOCK (pred
);
6883 basic_block s
= EXIT_BLOCK_PTR
;
6887 for (e
= p
->succ
; e
; e
= e
->succ_next
)
6893 for (e
= s
->pred
; e
; e
= e
->pred_next
)
6899 if (EDGE_INDEX (elist
, BASIC_BLOCK (pred
), EXIT_BLOCK_PTR
)
6900 == EDGE_INDEX_NO_EDGE
&& found_edge
!= 0)
6901 fprintf (f
, "*** Edge (%d, exit) appears to not have an index\n",
6903 if (EDGE_INDEX (elist
, BASIC_BLOCK (pred
), EXIT_BLOCK_PTR
)
6904 != EDGE_INDEX_NO_EDGE
&& found_edge
== 0)
6905 fprintf (f
, "*** Edge (%d, exit) has index %d, but no edge exists\n",
6906 pred
, EDGE_INDEX (elist
, BASIC_BLOCK (pred
),
6911 /* This routine will determine what, if any, edge there is between
6912 a specified predecessor and successor. */
6914 find_edge_index (edge_list
, pred
, succ
)
6915 struct edge_list
*edge_list
;
6916 basic_block pred
, succ
;
6919 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
6921 if (INDEX_EDGE_PRED_BB (edge_list
, x
) == pred
6922 && INDEX_EDGE_SUCC_BB (edge_list
, x
) == succ
)
6925 return (EDGE_INDEX_NO_EDGE
);
6928 /* This function will remove an edge from the flow graph. */
6933 edge last_pred
= NULL
;
6934 edge last_succ
= NULL
;
6936 basic_block src
, dest
;
6939 for (tmp
= src
->succ
; tmp
&& tmp
!= e
; tmp
= tmp
->succ_next
)
6945 last_succ
->succ_next
= e
->succ_next
;
6947 src
->succ
= e
->succ_next
;
6949 for (tmp
= dest
->pred
; tmp
&& tmp
!= e
; tmp
= tmp
->pred_next
)
6955 last_pred
->pred_next
= e
->pred_next
;
6957 dest
->pred
= e
->pred_next
;
6963 /* This routine will remove any fake successor edges for a basic block.
6964 When the edge is removed, it is also removed from whatever predecessor
6967 remove_fake_successors (bb
)
6971 for (e
= bb
->succ
; e
; )
6975 if ((tmp
->flags
& EDGE_FAKE
) == EDGE_FAKE
)
6980 /* This routine will remove all fake edges from the flow graph. If
6981 we remove all fake successors, it will automatically remove all
6982 fake predecessors. */
6984 remove_fake_edges ()
6988 for (x
= 0; x
< n_basic_blocks
; x
++)
6989 remove_fake_successors (BASIC_BLOCK (x
));
6991 /* We've handled all successors except the entry block's. */
6992 remove_fake_successors (ENTRY_BLOCK_PTR
);
6995 /* This function will add a fake edge between any block which has no
6996 successors, and the exit block. Some data flow equations require these
6999 add_noreturn_fake_exit_edges ()
7003 for (x
= 0; x
< n_basic_blocks
; x
++)
7004 if (BASIC_BLOCK (x
)->succ
== NULL
)
7005 make_edge (NULL
, BASIC_BLOCK (x
), EXIT_BLOCK_PTR
, EDGE_FAKE
);
7008 /* This function adds a fake edge between any infinite loops to the
7009 exit block. Some optimizations require a path from each node to
7012 See also Morgan, Figure 3.10, pp. 82-83.
7014 The current implementation is ugly, not attempting to minimize the
7015 number of inserted fake edges. To reduce the number of fake edges
7016 to insert, add fake edges from _innermost_ loops containing only
7017 nodes not reachable from the exit block. */
7019 connect_infinite_loops_to_exit ()
7021 basic_block unvisited_block
;
7023 /* Perform depth-first search in the reverse graph to find nodes
7024 reachable from the exit block. */
7025 struct depth_first_search_dsS dfs_ds
;
7027 flow_dfs_compute_reverse_init (&dfs_ds
);
7028 flow_dfs_compute_reverse_add_bb (&dfs_ds
, EXIT_BLOCK_PTR
);
7030 /* Repeatedly add fake edges, updating the unreachable nodes. */
7033 unvisited_block
= flow_dfs_compute_reverse_execute (&dfs_ds
);
7034 if (!unvisited_block
)
7036 make_edge (NULL
, unvisited_block
, EXIT_BLOCK_PTR
, EDGE_FAKE
);
7037 flow_dfs_compute_reverse_add_bb (&dfs_ds
, unvisited_block
);
7040 flow_dfs_compute_reverse_finish (&dfs_ds
);
7045 /* Redirect an edge's successor from one block to another. */
7047 redirect_edge_succ (e
, new_succ
)
7049 basic_block new_succ
;
7053 /* Disconnect the edge from the old successor block. */
7054 for (pe
= &e
->dest
->pred
; *pe
!= e
; pe
= &(*pe
)->pred_next
)
7056 *pe
= (*pe
)->pred_next
;
7058 /* Reconnect the edge to the new successor block. */
7059 e
->pred_next
= new_succ
->pred
;
7064 /* Redirect an edge's predecessor from one block to another. */
7066 redirect_edge_pred (e
, new_pred
)
7068 basic_block new_pred
;
7072 /* Disconnect the edge from the old predecessor block. */
7073 for (pe
= &e
->src
->succ
; *pe
!= e
; pe
= &(*pe
)->succ_next
)
7075 *pe
= (*pe
)->succ_next
;
7077 /* Reconnect the edge to the new predecessor block. */
7078 e
->succ_next
= new_pred
->succ
;
7083 /* Dump the list of basic blocks in the bitmap NODES. */
7085 flow_nodes_print (str
, nodes
, file
)
7087 const sbitmap nodes
;
7092 fprintf (file
, "%s { ", str
);
7093 EXECUTE_IF_SET_IN_SBITMAP (nodes
, 0, node
, {fprintf (file
, "%d ", node
);});
7094 fputs ("}\n", file
);
7098 /* Dump the list of exiting edges in the array EDGES. */
7100 flow_exits_print (str
, edges
, num_edges
, file
)
7108 fprintf (file
, "%s { ", str
);
7109 for (i
= 0; i
< num_edges
; i
++)
7110 fprintf (file
, "%d->%d ", edges
[i
]->src
->index
, edges
[i
]->dest
->index
);
7111 fputs ("}\n", file
);
7115 /* Dump loop related CFG information. */
7117 flow_loops_cfg_dump (loops
, file
)
7118 const struct loops
*loops
;
7123 if (! loops
->num
|| ! file
|| ! loops
->cfg
.dom
)
7126 for (i
= 0; i
< n_basic_blocks
; i
++)
7130 fprintf (file
, ";; %d succs { ", i
);
7131 for (succ
= BASIC_BLOCK (i
)->succ
; succ
; succ
= succ
->succ_next
)
7132 fprintf (file
, "%d ", succ
->dest
->index
);
7133 flow_nodes_print ("} dom", loops
->cfg
.dom
[i
], file
);
7137 /* Dump the DFS node order. */
7138 if (loops
->cfg
.dfs_order
)
7140 fputs (";; DFS order: ", file
);
7141 for (i
= 0; i
< n_basic_blocks
; i
++)
7142 fprintf (file
, "%d ", loops
->cfg
.dfs_order
[i
]);
7145 /* Dump the reverse completion node order. */
7146 if (loops
->cfg
.rc_order
)
7148 fputs (";; RC order: ", file
);
7149 for (i
= 0; i
< n_basic_blocks
; i
++)
7150 fprintf (file
, "%d ", loops
->cfg
.rc_order
[i
]);
7156 /* Return non-zero if the nodes of LOOP are a subset of OUTER. */
7158 flow_loop_nested_p (outer
, loop
)
7162 return sbitmap_a_subset_b_p (loop
->nodes
, outer
->nodes
);
7166 /* Dump the loop information specified by LOOPS to the stream FILE. */
7168 flow_loops_dump (loops
, file
, verbose
)
7169 const struct loops
*loops
;
7176 num_loops
= loops
->num
;
7177 if (! num_loops
|| ! file
)
7180 fprintf (file
, ";; %d loops found, %d levels\n",
7181 num_loops
, loops
->levels
);
7183 for (i
= 0; i
< num_loops
; i
++)
7185 struct loop
*loop
= &loops
->array
[i
];
7187 fprintf (file
, ";; loop %d (%d to %d):\n;; header %d, latch %d, pre-header %d, depth %d, level %d, outer %ld\n",
7188 i
, INSN_UID (loop
->header
->head
), INSN_UID (loop
->latch
->end
),
7189 loop
->header
->index
, loop
->latch
->index
,
7190 loop
->pre_header
? loop
->pre_header
->index
: -1,
7191 loop
->depth
, loop
->level
,
7192 (long) (loop
->outer
? (loop
->outer
- loops
->array
) : -1));
7193 fprintf (file
, ";; %d", loop
->num_nodes
);
7194 flow_nodes_print (" nodes", loop
->nodes
, file
);
7195 fprintf (file
, ";; %d", loop
->num_exits
);
7196 flow_exits_print (" exits", loop
->exits
, loop
->num_exits
, file
);
7202 for (j
= 0; j
< i
; j
++)
7204 struct loop
*oloop
= &loops
->array
[j
];
7206 if (loop
->header
== oloop
->header
)
7211 smaller
= loop
->num_nodes
< oloop
->num_nodes
;
7213 /* If the union of LOOP and OLOOP is different than
7214 the larger of LOOP and OLOOP then LOOP and OLOOP
7215 must be disjoint. */
7216 disjoint
= ! flow_loop_nested_p (smaller
? loop
: oloop
,
7217 smaller
? oloop
: loop
);
7219 ";; loop header %d shared by loops %d, %d %s\n",
7220 loop
->header
->index
, i
, j
,
7221 disjoint
? "disjoint" : "nested");
7228 /* Print diagnostics to compare our concept of a loop with
7229 what the loop notes say. */
7230 if (GET_CODE (PREV_INSN (loop
->first
->head
)) != NOTE
7231 || NOTE_LINE_NUMBER (PREV_INSN (loop
->first
->head
))
7232 != NOTE_INSN_LOOP_BEG
)
7233 fprintf (file
, ";; No NOTE_INSN_LOOP_BEG at %d\n",
7234 INSN_UID (PREV_INSN (loop
->first
->head
)));
7235 if (GET_CODE (NEXT_INSN (loop
->last
->end
)) != NOTE
7236 || NOTE_LINE_NUMBER (NEXT_INSN (loop
->last
->end
))
7237 != NOTE_INSN_LOOP_END
)
7238 fprintf (file
, ";; No NOTE_INSN_LOOP_END at %d\n",
7239 INSN_UID (NEXT_INSN (loop
->last
->end
)));
7244 flow_loops_cfg_dump (loops
, file
);
7248 /* Free all the memory allocated for LOOPS. */
7250 flow_loops_free (loops
)
7251 struct loops
*loops
;
7260 /* Free the loop descriptors. */
7261 for (i
= 0; i
< loops
->num
; i
++)
7263 struct loop
*loop
= &loops
->array
[i
];
7266 sbitmap_free (loop
->nodes
);
7270 free (loops
->array
);
7271 loops
->array
= NULL
;
7274 sbitmap_vector_free (loops
->cfg
.dom
);
7275 if (loops
->cfg
.dfs_order
)
7276 free (loops
->cfg
.dfs_order
);
7278 sbitmap_free (loops
->shared_headers
);
7283 /* Find the exits from the loop using the bitmap of loop nodes NODES
7284 and store in EXITS array. Return the number of exits from the
7287 flow_loop_exits_find (nodes
, exits
)
7288 const sbitmap nodes
;
7297 /* Check all nodes within the loop to see if there are any
7298 successors not in the loop. Note that a node may have multiple
7301 EXECUTE_IF_SET_IN_SBITMAP (nodes
, 0, node
, {
7302 for (e
= BASIC_BLOCK (node
)->succ
; e
; e
= e
->succ_next
)
7304 basic_block dest
= e
->dest
;
7306 if (dest
== EXIT_BLOCK_PTR
|| ! TEST_BIT (nodes
, dest
->index
))
7314 *exits
= (edge
*) xmalloc (num_exits
* sizeof (edge
*));
7316 /* Store all exiting edges into an array. */
7318 EXECUTE_IF_SET_IN_SBITMAP (nodes
, 0, node
, {
7319 for (e
= BASIC_BLOCK (node
)->succ
; e
; e
= e
->succ_next
)
7321 basic_block dest
= e
->dest
;
7323 if (dest
== EXIT_BLOCK_PTR
|| ! TEST_BIT (nodes
, dest
->index
))
7324 (*exits
)[num_exits
++] = e
;
7332 /* Find the nodes contained within the loop with header HEADER and
7333 latch LATCH and store in NODES. Return the number of nodes within
7336 flow_loop_nodes_find (header
, latch
, nodes
)
7345 stack
= (basic_block
*) xmalloc (n_basic_blocks
* sizeof (basic_block
));
7348 /* Start with only the loop header in the set of loop nodes. */
7349 sbitmap_zero (nodes
);
7350 SET_BIT (nodes
, header
->index
);
7352 header
->loop_depth
++;
7354 /* Push the loop latch on to the stack. */
7355 if (! TEST_BIT (nodes
, latch
->index
))
7357 SET_BIT (nodes
, latch
->index
);
7358 latch
->loop_depth
++;
7360 stack
[sp
++] = latch
;
7369 for (e
= node
->pred
; e
; e
= e
->pred_next
)
7371 basic_block ancestor
= e
->src
;
7373 /* If each ancestor not marked as part of loop, add to set of
7374 loop nodes and push on to stack. */
7375 if (ancestor
!= ENTRY_BLOCK_PTR
7376 && ! TEST_BIT (nodes
, ancestor
->index
))
7378 SET_BIT (nodes
, ancestor
->index
);
7379 ancestor
->loop_depth
++;
7381 stack
[sp
++] = ancestor
;
7390 /* Compute the depth first search order and store in the array
7391 DFS_ORDER if non-zero, marking the nodes visited in VISITED. If
7392 RC_ORDER is non-zero, return the reverse completion number for each
7393 node. Returns the number of nodes visited. A depth first search
7394 tries to get as far away from the starting point as quickly as
7397 flow_depth_first_order_compute (dfs_order
, rc_order
)
7404 int rcnum
= n_basic_blocks
- 1;
7407 /* Allocate stack for back-tracking up CFG. */
7408 stack
= (edge
*) xmalloc ((n_basic_blocks
+ 1) * sizeof (edge
));
7411 /* Allocate bitmap to track nodes that have been visited. */
7412 visited
= sbitmap_alloc (n_basic_blocks
);
7414 /* None of the nodes in the CFG have been visited yet. */
7415 sbitmap_zero (visited
);
7417 /* Push the first edge on to the stack. */
7418 stack
[sp
++] = ENTRY_BLOCK_PTR
->succ
;
7426 /* Look at the edge on the top of the stack. */
7431 /* Check if the edge destination has been visited yet. */
7432 if (dest
!= EXIT_BLOCK_PTR
&& ! TEST_BIT (visited
, dest
->index
))
7434 /* Mark that we have visited the destination. */
7435 SET_BIT (visited
, dest
->index
);
7438 dfs_order
[dfsnum
++] = dest
->index
;
7442 /* Since the DEST node has been visited for the first
7443 time, check its successors. */
7444 stack
[sp
++] = dest
->succ
;
7448 /* There are no successors for the DEST node so assign
7449 its reverse completion number. */
7451 rc_order
[rcnum
--] = dest
->index
;
7456 if (! e
->succ_next
&& src
!= ENTRY_BLOCK_PTR
)
7458 /* There are no more successors for the SRC node
7459 so assign its reverse completion number. */
7461 rc_order
[rcnum
--] = src
->index
;
7465 stack
[sp
- 1] = e
->succ_next
;
7472 sbitmap_free (visited
);
7474 /* The number of nodes visited should not be greater than
7476 if (dfsnum
> n_basic_blocks
)
7479 /* There are some nodes left in the CFG that are unreachable. */
7480 if (dfsnum
< n_basic_blocks
)
7486 /* Compute the depth first search order on the _reverse_ graph and
7487 store in the array DFS_ORDER, marking the nodes visited in VISITED.
7488 Returns the number of nodes visited.
7490 The computation is split into three pieces:
7492 flow_dfs_compute_reverse_init () creates the necessary data
7495 flow_dfs_compute_reverse_add_bb () adds a basic block to the data
7496 structures. The block will start the search.
7498 flow_dfs_compute_reverse_execute () continues (or starts) the
7499 search using the block on the top of the stack, stopping when the
7502 flow_dfs_compute_reverse_finish () destroys the necessary data
7505 Thus, the user will probably call ..._init(), call ..._add_bb() to
7506 add a beginning basic block to the stack, call ..._execute(),
7507 possibly add another bb to the stack and again call ..._execute(),
7508 ..., and finally call _finish(). */
7510 /* Initialize the data structures used for depth-first search on the
7511 reverse graph. If INITIALIZE_STACK is nonzero, the exit block is
7512 added to the basic block stack. DATA is the current depth-first
7513 search context. If INITIALIZE_STACK is non-zero, there is an
7514 element on the stack. */
7517 flow_dfs_compute_reverse_init (data
)
7518 depth_first_search_ds data
;
7520 /* Allocate stack for back-tracking up CFG. */
7522 (basic_block
*) xmalloc ((n_basic_blocks
- (INVALID_BLOCK
+1))
7523 * sizeof (basic_block
));
7526 /* Allocate bitmap to track nodes that have been visited. */
7527 data
->visited_blocks
7528 = sbitmap_alloc (n_basic_blocks
- (INVALID_BLOCK
+ 1));
7530 /* None of the nodes in the CFG have been visited yet. */
7531 sbitmap_zero (data
->visited_blocks
);
7536 /* Add the specified basic block to the top of the dfs data
7537 structures. When the search continues, it will start at the
7541 flow_dfs_compute_reverse_add_bb (data
, bb
)
7542 depth_first_search_ds data
;
7545 data
->stack
[data
->sp
++] = bb
;
7549 /* Continue the depth-first search through the reverse graph starting
7550 with the block at the stack's top and ending when the stack is
7551 empty. Visited nodes are marked. Returns an unvisited basic
7552 block, or NULL if there is none available. */
7554 flow_dfs_compute_reverse_execute (data
)
7555 depth_first_search_ds data
;
7561 while (data
->sp
> 0)
7563 bb
= data
->stack
[--data
->sp
];
7565 /* Mark that we have visited this node. */
7566 if (!TEST_BIT (data
->visited_blocks
, bb
->index
- (INVALID_BLOCK
+1)))
7568 SET_BIT (data
->visited_blocks
, bb
->index
- (INVALID_BLOCK
+1));
7570 /* Perform depth-first search on adjacent vertices. */
7571 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
7572 flow_dfs_compute_reverse_add_bb (data
, e
->src
);
7576 /* Determine if there are unvisited basic blocks. */
7577 for (i
= n_basic_blocks
- (INVALID_BLOCK
+1); --i
>= 0; )
7578 if (!TEST_BIT (data
->visited_blocks
, i
))
7579 return BASIC_BLOCK (i
+ (INVALID_BLOCK
+1));
7583 /* Destroy the data structures needed for depth-first search on the
7587 flow_dfs_compute_reverse_finish (data
)
7588 depth_first_search_ds data
;
7591 sbitmap_free (data
->visited_blocks
);
7595 /* Return the block for the pre-header of the loop with header
7596 HEADER where DOM specifies the dominator information. Return NULL if
7597 there is no pre-header. */
7599 flow_loop_pre_header_find (header
, dom
)
7603 basic_block pre_header
;
7606 /* If block p is a predecessor of the header and is the only block
7607 that the header does not dominate, then it is the pre-header. */
7609 for (e
= header
->pred
; e
; e
= e
->pred_next
)
7611 basic_block node
= e
->src
;
7613 if (node
!= ENTRY_BLOCK_PTR
7614 && ! TEST_BIT (dom
[node
->index
], header
->index
))
7616 if (pre_header
== NULL
)
7620 /* There are multiple edges into the header from outside
7621 the loop so there is no pre-header block. */
7631 /* Add LOOP to the loop hierarchy tree where PREVLOOP was the loop
7632 previously added. The insertion algorithm assumes that the loops
7633 are added in the order found by a depth first search of the CFG. */
7635 flow_loop_tree_node_add (prevloop
, loop
)
7636 struct loop
*prevloop
;
7640 if (flow_loop_nested_p (prevloop
, loop
))
7642 prevloop
->inner
= loop
;
7643 loop
->outer
= prevloop
;
7647 while (prevloop
->outer
)
7649 if (flow_loop_nested_p (prevloop
->outer
, loop
))
7651 prevloop
->next
= loop
;
7652 loop
->outer
= prevloop
->outer
;
7655 prevloop
= prevloop
->outer
;
7658 prevloop
->next
= loop
;
7663 /* Build the loop hierarchy tree for LOOPS. */
7665 flow_loops_tree_build (loops
)
7666 struct loops
*loops
;
7671 num_loops
= loops
->num
;
7675 /* Root the loop hierarchy tree with the first loop found.
7676 Since we used a depth first search this should be the
7678 loops
->tree
= &loops
->array
[0];
7679 loops
->tree
->outer
= loops
->tree
->inner
= loops
->tree
->next
= NULL
;
7681 /* Add the remaining loops to the tree. */
7682 for (i
= 1; i
< num_loops
; i
++)
7683 flow_loop_tree_node_add (&loops
->array
[i
- 1], &loops
->array
[i
]);
7687 /* Helper function to compute loop nesting depth and enclosed loop level
7688 for the natural loop specified by LOOP at the loop depth DEPTH.
7689 Returns the loop level. */
7691 flow_loop_level_compute (loop
, depth
)
7701 /* Traverse loop tree assigning depth and computing level as the
7702 maximum level of all the inner loops of this loop. The loop
7703 level is equivalent to the height of the loop in the loop tree
7704 and corresponds to the number of enclosed loop levels (including
7706 for (inner
= loop
->inner
; inner
; inner
= inner
->next
)
7710 ilevel
= flow_loop_level_compute (inner
, depth
+ 1) + 1;
7715 loop
->level
= level
;
7716 loop
->depth
= depth
;
7721 /* Compute the loop nesting depth and enclosed loop level for the loop
7722 hierarchy tree specfied by LOOPS. Return the maximum enclosed loop
7726 flow_loops_level_compute (loops
)
7727 struct loops
*loops
;
7733 /* Traverse all the outer level loops. */
7734 for (loop
= loops
->tree
; loop
; loop
= loop
->next
)
7736 level
= flow_loop_level_compute (loop
, 1);
7744 /* Find all the natural loops in the function and save in LOOPS structure
7745 and recalculate loop_depth information in basic block structures.
7746 Return the number of natural loops found. */
7749 flow_loops_find (loops
)
7750 struct loops
*loops
;
7762 loops
->array
= NULL
;
7767 /* Taking care of this degenerate case makes the rest of
7768 this code simpler. */
7769 if (n_basic_blocks
== 0)
7772 /* Compute the dominators. */
7773 dom
= sbitmap_vector_alloc (n_basic_blocks
, n_basic_blocks
);
7774 compute_flow_dominators (dom
, NULL
);
7776 /* Count the number of loop edges (back edges). This should be the
7777 same as the number of natural loops. Also clear the loop_depth
7778 and as we work from inner->outer in a loop nest we call
7779 find_loop_nodes_find which will increment loop_depth for nodes
7780 within the current loop, which happens to enclose inner loops. */
7783 for (b
= 0; b
< n_basic_blocks
; b
++)
7785 BASIC_BLOCK (b
)->loop_depth
= 0;
7786 for (e
= BASIC_BLOCK (b
)->pred
; e
; e
= e
->pred_next
)
7788 basic_block latch
= e
->src
;
7790 /* Look for back edges where a predecessor is dominated
7791 by this block. A natural loop has a single entry
7792 node (header) that dominates all the nodes in the
7793 loop. It also has single back edge to the header
7794 from a latch node. Note that multiple natural loops
7795 may share the same header. */
7796 if (latch
!= ENTRY_BLOCK_PTR
&& TEST_BIT (dom
[latch
->index
], b
))
7803 /* Compute depth first search order of the CFG so that outer
7804 natural loops will be found before inner natural loops. */
7805 dfs_order
= (int *) xmalloc (n_basic_blocks
* sizeof (int));
7806 rc_order
= (int *) xmalloc (n_basic_blocks
* sizeof (int));
7807 flow_depth_first_order_compute (dfs_order
, rc_order
);
7809 /* Allocate loop structures. */
7811 = (struct loop
*) xcalloc (num_loops
, sizeof (struct loop
));
7813 headers
= sbitmap_alloc (n_basic_blocks
);
7814 sbitmap_zero (headers
);
7816 loops
->shared_headers
= sbitmap_alloc (n_basic_blocks
);
7817 sbitmap_zero (loops
->shared_headers
);
7819 /* Find and record information about all the natural loops
7822 for (b
= 0; b
< n_basic_blocks
; b
++)
7826 /* Search the nodes of the CFG in DFS order that we can find
7827 outer loops first. */
7828 header
= BASIC_BLOCK (rc_order
[b
]);
7830 /* Look for all the possible latch blocks for this header. */
7831 for (e
= header
->pred
; e
; e
= e
->pred_next
)
7833 basic_block latch
= e
->src
;
7835 /* Look for back edges where a predecessor is dominated
7836 by this block. A natural loop has a single entry
7837 node (header) that dominates all the nodes in the
7838 loop. It also has single back edge to the header
7839 from a latch node. Note that multiple natural loops
7840 may share the same header. */
7841 if (latch
!= ENTRY_BLOCK_PTR
7842 && TEST_BIT (dom
[latch
->index
], header
->index
))
7846 loop
= loops
->array
+ num_loops
;
7848 loop
->header
= header
;
7849 loop
->latch
= latch
;
7850 loop
->num
= num_loops
;
7852 /* Keep track of blocks that are loop headers so
7853 that we can tell which loops should be merged. */
7854 if (TEST_BIT (headers
, header
->index
))
7855 SET_BIT (loops
->shared_headers
, header
->index
);
7856 SET_BIT (headers
, header
->index
);
7858 /* Find nodes contained within the loop. */
7859 loop
->nodes
= sbitmap_alloc (n_basic_blocks
);
7861 = flow_loop_nodes_find (header
, latch
, loop
->nodes
);
7863 /* Compute first and last blocks within the loop.
7864 These are often the same as the loop header and
7865 loop latch respectively, but this is not always
7868 = BASIC_BLOCK (sbitmap_first_set_bit (loop
->nodes
));
7870 = BASIC_BLOCK (sbitmap_last_set_bit (loop
->nodes
));
7872 /* Find edges which exit the loop. Note that a node
7873 may have several exit edges. */
7875 = flow_loop_exits_find (loop
->nodes
, &loop
->exits
);
7877 /* Look to see if the loop has a pre-header node. */
7879 = flow_loop_pre_header_find (header
, dom
);
7886 /* Natural loops with shared headers may either be disjoint or
7887 nested. Disjoint loops with shared headers cannot be inner
7888 loops and should be merged. For now just mark loops that share
7890 for (i
= 0; i
< num_loops
; i
++)
7891 if (TEST_BIT (loops
->shared_headers
, loops
->array
[i
].header
->index
))
7892 loops
->array
[i
].shared
= 1;
7894 sbitmap_free (headers
);
7897 loops
->num
= num_loops
;
7899 /* Save CFG derived information to avoid recomputing it. */
7900 loops
->cfg
.dom
= dom
;
7901 loops
->cfg
.dfs_order
= dfs_order
;
7902 loops
->cfg
.rc_order
= rc_order
;
7904 /* Build the loop hierarchy tree. */
7905 flow_loops_tree_build (loops
);
7907 /* Assign the loop nesting depth and enclosed loop level for each
7909 loops
->levels
= flow_loops_level_compute (loops
);
7915 /* Return non-zero if edge E enters header of LOOP from outside of LOOP. */
7918 flow_loop_outside_edge_p (loop
, e
)
7919 const struct loop
*loop
;
7922 if (e
->dest
!= loop
->header
)
7924 return (e
->src
== ENTRY_BLOCK_PTR
)
7925 || ! TEST_BIT (loop
->nodes
, e
->src
->index
);
7929 /* Clear LOG_LINKS fields of insns in a chain.
7930 Also clear the global_live_at_{start,end} fields of the basic block
7934 clear_log_links (insns
)
7940 for (i
= insns
; i
; i
= NEXT_INSN (i
))
7944 for (b
= 0; b
< n_basic_blocks
; b
++)
7946 basic_block bb
= BASIC_BLOCK (b
);
7948 bb
->global_live_at_start
= NULL
;
7949 bb
->global_live_at_end
= NULL
;
7952 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
7953 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
7956 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
7957 correspond to the hard registers, if any, set in that map. This
7958 could be done far more efficiently by having all sorts of special-cases
7959 with moving single words, but probably isn't worth the trouble. */
7962 reg_set_to_hard_reg_set (to
, from
)
7968 EXECUTE_IF_SET_IN_BITMAP
7971 if (i
>= FIRST_PSEUDO_REGISTER
)
7973 SET_HARD_REG_BIT (*to
, i
);