1 /* High-level loop manipulation functions.
2 Copyright (C) 2004-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 3, or (at your option) any
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
22 #include "coretypes.h"
27 #include "hard-reg-set.h"
30 #include "fold-const.h"
33 #include "internal-fn.h"
35 #include "gimple-iterator.h"
36 #include "gimplify-me.h"
38 #include "tree-ssa-loop-ivopts.h"
39 #include "tree-ssa-loop-manip.h"
40 #include "tree-ssa-loop-niter.h"
41 #include "tree-ssa-loop.h"
42 #include "tree-into-ssa.h"
45 #include "gimple-pretty-print.h"
47 #include "tree-pass.h" /* ??? for TODO_update_ssa but this isn't a pass. */
48 #include "tree-scalar-evolution.h"
50 #include "tree-inline.h"
51 #include "langhooks.h"
53 /* All bitmaps for rewriting into loop-closed SSA go on this obstack,
54 so that we can free them all at once. */
55 static bitmap_obstack loop_renamer_obstack
;
57 /* Creates an induction variable with value BASE + STEP * iteration in LOOP.
58 It is expected that neither BASE nor STEP are shared with other expressions
59 (unless the sharing rules allow this). Use VAR as a base var_decl for it
60 (if NULL, a new temporary will be created). The increment will occur at
61 INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and
62 AFTER can be computed using standard_iv_increment_position. The ssa versions
63 of the variable before and after increment will be stored in VAR_BEFORE and
64 VAR_AFTER (unless they are NULL). */
67 create_iv (tree base
, tree step
, tree var
, struct loop
*loop
,
68 gimple_stmt_iterator
*incr_pos
, bool after
,
69 tree
*var_before
, tree
*var_after
)
76 enum tree_code incr_op
= PLUS_EXPR
;
77 edge pe
= loop_preheader_edge (loop
);
81 vb
= make_ssa_name (var
);
82 va
= make_ssa_name (var
);
86 vb
= make_temp_ssa_name (TREE_TYPE (base
), NULL
, "ivtmp");
87 va
= make_temp_ssa_name (TREE_TYPE (base
), NULL
, "ivtmp");
94 /* For easier readability of the created code, produce MINUS_EXPRs
96 if (TREE_CODE (step
) == INTEGER_CST
)
98 if (TYPE_UNSIGNED (TREE_TYPE (step
)))
100 step1
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (step
), step
);
101 if (tree_int_cst_lt (step1
, step
))
103 incr_op
= MINUS_EXPR
;
111 if (!tree_expr_nonnegative_warnv_p (step
, &ovf
)
112 && may_negate_without_overflow_p (step
))
114 incr_op
= MINUS_EXPR
;
115 step
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (step
), step
);
119 if (POINTER_TYPE_P (TREE_TYPE (base
)))
121 if (TREE_CODE (base
) == ADDR_EXPR
)
122 mark_addressable (TREE_OPERAND (base
, 0));
123 step
= convert_to_ptrofftype (step
);
124 if (incr_op
== MINUS_EXPR
)
125 step
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (step
), step
);
126 incr_op
= POINTER_PLUS_EXPR
;
128 /* Gimplify the step if necessary. We put the computations in front of the
129 loop (i.e. the step should be loop invariant). */
130 step
= force_gimple_operand (step
, &stmts
, true, NULL_TREE
);
132 gsi_insert_seq_on_edge_immediate (pe
, stmts
);
134 stmt
= gimple_build_assign (va
, incr_op
, vb
, step
);
136 gsi_insert_after (incr_pos
, stmt
, GSI_NEW_STMT
);
138 gsi_insert_before (incr_pos
, stmt
, GSI_NEW_STMT
);
140 initial
= force_gimple_operand (base
, &stmts
, true, var
);
142 gsi_insert_seq_on_edge_immediate (pe
, stmts
);
144 phi
= create_phi_node (vb
, loop
->header
);
145 add_phi_arg (phi
, initial
, loop_preheader_edge (loop
), UNKNOWN_LOCATION
);
146 add_phi_arg (phi
, va
, loop_latch_edge (loop
), UNKNOWN_LOCATION
);
149 /* Return the innermost superloop LOOP of USE_LOOP that is a superloop of
150 both DEF_LOOP and USE_LOOP. */
152 static inline struct loop
*
153 find_sibling_superloop (struct loop
*use_loop
, struct loop
*def_loop
)
155 unsigned ud
= loop_depth (use_loop
);
156 unsigned dd
= loop_depth (def_loop
);
157 gcc_assert (ud
> 0 && dd
> 0);
159 use_loop
= superloop_at_depth (use_loop
, dd
);
161 def_loop
= superloop_at_depth (def_loop
, ud
);
162 while (loop_outer (use_loop
) != loop_outer (def_loop
))
164 use_loop
= loop_outer (use_loop
);
165 def_loop
= loop_outer (def_loop
);
166 gcc_assert (use_loop
&& def_loop
);
171 /* DEF_BB is a basic block containing a DEF that needs rewriting into
172 loop-closed SSA form. USE_BLOCKS is the set of basic blocks containing
173 uses of DEF that "escape" from the loop containing DEF_BB (i.e. blocks in
174 USE_BLOCKS are dominated by DEF_BB but not in the loop father of DEF_B).
175 ALL_EXITS[I] is the set of all basic blocks that exit loop I.
177 Compute the subset of LOOP_EXITS that exit the loop containing DEF_BB
178 or one of its loop fathers, in which DEF is live. This set is returned
179 in the bitmap LIVE_EXITS.
181 Instead of computing the complete livein set of the def, we use the loop
182 nesting tree as a form of poor man's structure analysis. This greatly
183 speeds up the analysis, which is important because this function may be
184 called on all SSA names that need rewriting, one at a time. */
187 compute_live_loop_exits (bitmap live_exits
, bitmap use_blocks
,
188 bitmap
*loop_exits
, basic_block def_bb
)
192 struct loop
*def_loop
= def_bb
->loop_father
;
193 unsigned def_loop_depth
= loop_depth (def_loop
);
194 bitmap def_loop_exits
;
196 /* Normally the work list size is bounded by the number of basic
197 blocks in the largest loop. We don't know this number, but we
198 can be fairly sure that it will be relatively small. */
199 auto_vec
<basic_block
> worklist (MAX (8, n_basic_blocks_for_fn (cfun
) / 128));
201 EXECUTE_IF_SET_IN_BITMAP (use_blocks
, 0, i
, bi
)
203 basic_block use_bb
= BASIC_BLOCK_FOR_FN (cfun
, i
);
204 struct loop
*use_loop
= use_bb
->loop_father
;
205 gcc_checking_assert (def_loop
!= use_loop
206 && ! flow_loop_nested_p (def_loop
, use_loop
));
207 if (! flow_loop_nested_p (use_loop
, def_loop
))
208 use_bb
= find_sibling_superloop (use_loop
, def_loop
)->header
;
209 if (bitmap_set_bit (live_exits
, use_bb
->index
))
210 worklist
.safe_push (use_bb
);
213 /* Iterate until the worklist is empty. */
214 while (! worklist
.is_empty ())
219 /* Pull a block off the worklist. */
220 basic_block bb
= worklist
.pop ();
222 /* Make sure we have at least enough room in the work list
223 for all predecessors of this block. */
224 worklist
.reserve (EDGE_COUNT (bb
->preds
));
226 /* For each predecessor block. */
227 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
229 basic_block pred
= e
->src
;
230 struct loop
*pred_loop
= pred
->loop_father
;
231 unsigned pred_loop_depth
= loop_depth (pred_loop
);
234 /* We should have met DEF_BB along the way. */
235 gcc_assert (pred
!= ENTRY_BLOCK_PTR_FOR_FN (cfun
));
237 if (pred_loop_depth
>= def_loop_depth
)
239 if (pred_loop_depth
> def_loop_depth
)
240 pred_loop
= superloop_at_depth (pred_loop
, def_loop_depth
);
241 /* If we've reached DEF_LOOP, our train ends here. */
242 if (pred_loop
== def_loop
)
245 else if (! flow_loop_nested_p (pred_loop
, def_loop
))
246 pred
= find_sibling_superloop (pred_loop
, def_loop
)->header
;
248 /* Add PRED to the LIVEIN set. PRED_VISITED is true if
249 we had already added PRED to LIVEIN before. */
250 pred_visited
= !bitmap_set_bit (live_exits
, pred
->index
);
252 /* If we have visited PRED before, don't add it to the worklist.
253 If BB dominates PRED, then we're probably looking at a loop.
254 We're only interested in looking up in the dominance tree
255 because DEF_BB dominates all the uses. */
256 if (pred_visited
|| dominated_by_p (CDI_DOMINATORS
, pred
, bb
))
259 worklist
.quick_push (pred
);
263 def_loop_exits
= BITMAP_ALLOC (&loop_renamer_obstack
);
264 for (struct loop
*loop
= def_loop
;
265 loop
!= current_loops
->tree_root
;
266 loop
= loop_outer (loop
))
267 bitmap_ior_into (def_loop_exits
, loop_exits
[loop
->num
]);
268 bitmap_and_into (live_exits
, def_loop_exits
);
269 BITMAP_FREE (def_loop_exits
);
272 /* Add a loop-closing PHI for VAR in basic block EXIT. */
275 add_exit_phi (basic_block exit
, tree var
)
281 #ifdef ENABLE_CHECKING
282 /* Check that at least one of the edges entering the EXIT block exits
283 the loop, or a superloop of that loop, that VAR is defined in. */
284 gimple def_stmt
= SSA_NAME_DEF_STMT (var
);
285 basic_block def_bb
= gimple_bb (def_stmt
);
286 FOR_EACH_EDGE (e
, ei
, exit
->preds
)
288 struct loop
*aloop
= find_common_loop (def_bb
->loop_father
,
289 e
->src
->loop_father
);
290 if (!flow_bb_inside_loop_p (aloop
, e
->dest
))
294 gcc_checking_assert (e
);
297 phi
= create_phi_node (NULL_TREE
, exit
);
298 create_new_def_for (var
, phi
, gimple_phi_result_ptr (phi
));
299 FOR_EACH_EDGE (e
, ei
, exit
->preds
)
300 add_phi_arg (phi
, var
, e
, UNKNOWN_LOCATION
);
302 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
304 fprintf (dump_file
, ";; Created LCSSA PHI: ");
305 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
309 /* Add exit phis for VAR that is used in LIVEIN.
310 Exits of the loops are stored in LOOP_EXITS. */
313 add_exit_phis_var (tree var
, bitmap use_blocks
, bitmap
*loop_exits
)
317 basic_block def_bb
= gimple_bb (SSA_NAME_DEF_STMT (var
));
318 bitmap live_exits
= BITMAP_ALLOC (&loop_renamer_obstack
);
320 gcc_checking_assert (! bitmap_bit_p (use_blocks
, def_bb
->index
));
322 compute_live_loop_exits (live_exits
, use_blocks
, loop_exits
, def_bb
);
324 EXECUTE_IF_SET_IN_BITMAP (live_exits
, 0, index
, bi
)
326 add_exit_phi (BASIC_BLOCK_FOR_FN (cfun
, index
), var
);
329 BITMAP_FREE (live_exits
);
332 /* Add exit phis for the names marked in NAMES_TO_RENAME.
333 Exits of the loops are stored in EXITS. Sets of blocks where the ssa
334 names are used are stored in USE_BLOCKS. */
337 add_exit_phis (bitmap names_to_rename
, bitmap
*use_blocks
, bitmap
*loop_exits
)
342 EXECUTE_IF_SET_IN_BITMAP (names_to_rename
, 0, i
, bi
)
344 add_exit_phis_var (ssa_name (i
), use_blocks
[i
], loop_exits
);
348 /* Fill the array of bitmaps LOOP_EXITS with all loop exit edge targets. */
351 get_loops_exits (bitmap
*loop_exits
)
357 FOR_EACH_LOOP (loop
, 0)
359 vec
<edge
> exit_edges
= get_loop_exit_edges (loop
);
360 loop_exits
[loop
->num
] = BITMAP_ALLOC (&loop_renamer_obstack
);
361 FOR_EACH_VEC_ELT (exit_edges
, j
, e
)
362 bitmap_set_bit (loop_exits
[loop
->num
], e
->dest
->index
);
363 exit_edges
.release ();
367 /* For USE in BB, if it is used outside of the loop it is defined in,
368 mark it for rewrite. Record basic block BB where it is used
369 to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap. */
372 find_uses_to_rename_use (basic_block bb
, tree use
, bitmap
*use_blocks
,
377 struct loop
*def_loop
;
379 if (TREE_CODE (use
) != SSA_NAME
)
382 ver
= SSA_NAME_VERSION (use
);
383 def_bb
= gimple_bb (SSA_NAME_DEF_STMT (use
));
386 def_loop
= def_bb
->loop_father
;
388 /* If the definition is not inside a loop, it is not interesting. */
389 if (!loop_outer (def_loop
))
392 /* If the use is not outside of the loop it is defined in, it is not
394 if (flow_bb_inside_loop_p (def_loop
, bb
))
397 /* If we're seeing VER for the first time, we still have to allocate
398 a bitmap for its uses. */
399 if (bitmap_set_bit (need_phis
, ver
))
400 use_blocks
[ver
] = BITMAP_ALLOC (&loop_renamer_obstack
);
401 bitmap_set_bit (use_blocks
[ver
], bb
->index
);
404 /* For uses in STMT, mark names that are used outside of the loop they are
405 defined to rewrite. Record the set of blocks in that the ssa
406 names are defined to USE_BLOCKS and the ssa names themselves to
410 find_uses_to_rename_stmt (gimple stmt
, bitmap
*use_blocks
, bitmap need_phis
)
414 basic_block bb
= gimple_bb (stmt
);
416 if (is_gimple_debug (stmt
))
419 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_USE
)
420 find_uses_to_rename_use (bb
, var
, use_blocks
, need_phis
);
423 /* Marks names that are used in BB and outside of the loop they are
424 defined in for rewrite. Records the set of blocks in that the ssa
425 names are defined to USE_BLOCKS. Record the SSA names that will
426 need exit PHIs in NEED_PHIS. */
429 find_uses_to_rename_bb (basic_block bb
, bitmap
*use_blocks
, bitmap need_phis
)
434 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
435 for (gphi_iterator bsi
= gsi_start_phis (e
->dest
); !gsi_end_p (bsi
);
438 gphi
*phi
= bsi
.phi ();
439 if (! virtual_operand_p (gimple_phi_result (phi
)))
440 find_uses_to_rename_use (bb
, PHI_ARG_DEF_FROM_EDGE (phi
, e
),
441 use_blocks
, need_phis
);
444 for (gimple_stmt_iterator bsi
= gsi_start_bb (bb
); !gsi_end_p (bsi
);
446 find_uses_to_rename_stmt (gsi_stmt (bsi
), use_blocks
, need_phis
);
449 /* Marks names that are used outside of the loop they are defined in
450 for rewrite. Records the set of blocks in that the ssa
451 names are defined to USE_BLOCKS. If CHANGED_BBS is not NULL,
452 scan only blocks in this set. */
455 find_uses_to_rename (bitmap changed_bbs
, bitmap
*use_blocks
, bitmap need_phis
)
462 EXECUTE_IF_SET_IN_BITMAP (changed_bbs
, 0, index
, bi
)
463 find_uses_to_rename_bb (BASIC_BLOCK_FOR_FN (cfun
, index
), use_blocks
, need_phis
);
465 FOR_EACH_BB_FN (bb
, cfun
)
466 find_uses_to_rename_bb (bb
, use_blocks
, need_phis
);
469 /* Rewrites the program into a loop closed ssa form -- i.e. inserts extra
470 phi nodes to ensure that no variable is used outside the loop it is
473 This strengthening of the basic ssa form has several advantages:
475 1) Updating it during unrolling/peeling/versioning is trivial, since
476 we do not need to care about the uses outside of the loop.
477 The same applies to virtual operands which are also rewritten into
478 loop closed SSA form. Note that virtual operands are always live
480 2) The behavior of all uses of an induction variable is the same.
481 Without this, you need to distinguish the case when the variable
482 is used outside of the loop it is defined in, for example
484 for (i = 0; i < 100; i++)
486 for (j = 0; j < 100; j++)
494 Looking from the outer loop with the normal SSA form, the first use of k
495 is not well-behaved, while the second one is an induction variable with
498 If CHANGED_BBS is not NULL, we look for uses outside loops only in
499 the basic blocks in this set.
501 UPDATE_FLAG is used in the call to update_ssa. See
502 TODO_update_ssa* for documentation. */
505 rewrite_into_loop_closed_ssa (bitmap changed_bbs
, unsigned update_flag
)
508 bitmap names_to_rename
;
510 loops_state_set (LOOP_CLOSED_SSA
);
511 if (number_of_loops (cfun
) <= 1)
514 /* If the pass has caused the SSA form to be out-of-date, update it
516 update_ssa (update_flag
);
518 bitmap_obstack_initialize (&loop_renamer_obstack
);
520 names_to_rename
= BITMAP_ALLOC (&loop_renamer_obstack
);
522 /* Uses of names to rename. We don't have to initialize this array,
523 because we know that we will only have entries for the SSA names
524 in NAMES_TO_RENAME. */
525 use_blocks
= XNEWVEC (bitmap
, num_ssa_names
);
527 /* Find the uses outside loops. */
528 find_uses_to_rename (changed_bbs
, use_blocks
, names_to_rename
);
530 if (!bitmap_empty_p (names_to_rename
))
532 /* An array of bitmaps where LOOP_EXITS[I] is the set of basic blocks
533 that are the destination of an edge exiting loop number I. */
534 bitmap
*loop_exits
= XNEWVEC (bitmap
, number_of_loops (cfun
));
535 get_loops_exits (loop_exits
);
537 /* Add the PHI nodes on exits of the loops for the names we need to
539 add_exit_phis (names_to_rename
, use_blocks
, loop_exits
);
543 /* Fix up all the names found to be used outside their original
545 update_ssa (TODO_update_ssa
);
548 bitmap_obstack_release (&loop_renamer_obstack
);
552 /* Replace uses of OLD_VAL with NEW_VAL in bbs dominated by BB. */
555 replace_uses_in_dominated_bbs (tree old_val
, tree new_val
, basic_block bb
)
558 imm_use_iterator imm_iter
;
560 FOR_EACH_IMM_USE_STMT (use_stmt
, imm_iter
, old_val
)
562 if (!dominated_by_p (CDI_DOMINATORS
, gimple_bb (use_stmt
), bb
))
566 FOR_EACH_IMM_USE_ON_STMT (use_p
, imm_iter
)
567 SET_USE (use_p
, new_val
);
571 /* Ensure a virtual phi is present in the exit block, if LOOP contains a vdef.
572 In other words, ensure loop-closed ssa normal form for virtuals. Handles
573 only loops with a single exit that dominates the latch. */
576 rewrite_virtuals_into_loop_closed_ssa (struct loop
*loop
)
579 /* TODO: Handle !single_dom_exit loops. */
580 edge exit
= single_dom_exit (loop
);
581 gcc_assert (exit
!= NULL
);
583 phi
= get_virtual_phi (loop
->header
);
587 tree final_loop
= PHI_ARG_DEF_FROM_EDGE (phi
, single_succ_edge (loop
->latch
));
589 phi
= get_virtual_phi (exit
->dest
);
592 tree final_exit
= PHI_ARG_DEF_FROM_EDGE (phi
, exit
);
593 gcc_assert (operand_equal_p (final_loop
, final_exit
, 0));
597 tree res_new
= copy_ssa_name (final_loop
, NULL
);
598 gphi
*nphi
= create_phi_node (res_new
, exit
->dest
);
599 replace_uses_in_dominated_bbs (final_loop
, res_new
, exit
->dest
);
600 add_phi_arg (nphi
, final_loop
, exit
, UNKNOWN_LOCATION
);
603 /* Check invariants of the loop closed ssa form for the USE in BB. */
606 check_loop_closed_ssa_use (basic_block bb
, tree use
)
611 if (TREE_CODE (use
) != SSA_NAME
|| virtual_operand_p (use
))
614 def
= SSA_NAME_DEF_STMT (use
);
615 def_bb
= gimple_bb (def
);
617 || flow_bb_inside_loop_p (def_bb
->loop_father
, bb
));
620 /* Checks invariants of loop closed ssa form in statement STMT in BB. */
623 check_loop_closed_ssa_stmt (basic_block bb
, gimple stmt
)
628 if (is_gimple_debug (stmt
))
631 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_USE
)
632 check_loop_closed_ssa_use (bb
, var
);
635 /* Checks that invariants of the loop closed ssa form are preserved.
636 Call verify_ssa when VERIFY_SSA_P is true. */
639 verify_loop_closed_ssa (bool verify_ssa_p
)
645 if (number_of_loops (cfun
) <= 1)
649 verify_ssa (false, true);
651 timevar_push (TV_VERIFY_LOOP_CLOSED
);
653 FOR_EACH_BB_FN (bb
, cfun
)
655 for (gphi_iterator bsi
= gsi_start_phis (bb
); !gsi_end_p (bsi
);
658 gphi
*phi
= bsi
.phi ();
659 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
660 check_loop_closed_ssa_use (e
->src
,
661 PHI_ARG_DEF_FROM_EDGE (phi
, e
));
664 for (gimple_stmt_iterator bsi
= gsi_start_bb (bb
); !gsi_end_p (bsi
);
666 check_loop_closed_ssa_stmt (bb
, gsi_stmt (bsi
));
669 timevar_pop (TV_VERIFY_LOOP_CLOSED
);
672 /* Split loop exit edge EXIT. The things are a bit complicated by a need to
673 preserve the loop closed ssa form. The newly created block is returned. */
676 split_loop_exit_edge (edge exit
)
678 basic_block dest
= exit
->dest
;
679 basic_block bb
= split_edge (exit
);
684 source_location locus
;
686 for (psi
= gsi_start_phis (dest
); !gsi_end_p (psi
); gsi_next (&psi
))
689 op_p
= PHI_ARG_DEF_PTR_FROM_EDGE (phi
, single_succ_edge (bb
));
690 locus
= gimple_phi_arg_location_from_edge (phi
, single_succ_edge (bb
));
692 name
= USE_FROM_PTR (op_p
);
694 /* If the argument of the PHI node is a constant, we do not need
695 to keep it inside loop. */
696 if (TREE_CODE (name
) != SSA_NAME
)
699 /* Otherwise create an auxiliary phi node that will copy the value
700 of the SSA name out of the loop. */
701 new_name
= duplicate_ssa_name (name
, NULL
);
702 new_phi
= create_phi_node (new_name
, bb
);
703 add_phi_arg (new_phi
, name
, exit
, locus
);
704 SET_USE (op_p
, new_name
);
710 /* Returns the basic block in that statements should be emitted for induction
711 variables incremented at the end of the LOOP. */
714 ip_end_pos (struct loop
*loop
)
719 /* Returns the basic block in that statements should be emitted for induction
720 variables incremented just before exit condition of a LOOP. */
723 ip_normal_pos (struct loop
*loop
)
729 if (!single_pred_p (loop
->latch
))
732 bb
= single_pred (loop
->latch
);
733 last
= last_stmt (bb
);
735 || gimple_code (last
) != GIMPLE_COND
)
738 exit
= EDGE_SUCC (bb
, 0);
739 if (exit
->dest
== loop
->latch
)
740 exit
= EDGE_SUCC (bb
, 1);
742 if (flow_bb_inside_loop_p (loop
, exit
->dest
))
748 /* Stores the standard position for induction variable increment in LOOP
749 (just before the exit condition if it is available and latch block is empty,
750 end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if
751 the increment should be inserted after *BSI. */
754 standard_iv_increment_position (struct loop
*loop
, gimple_stmt_iterator
*bsi
,
757 basic_block bb
= ip_normal_pos (loop
), latch
= ip_end_pos (loop
);
758 gimple last
= last_stmt (latch
);
761 || (last
&& gimple_code (last
) != GIMPLE_LABEL
))
763 *bsi
= gsi_last_bb (latch
);
764 *insert_after
= true;
768 *bsi
= gsi_last_bb (bb
);
769 *insert_after
= false;
773 /* Copies phi node arguments for duplicated blocks. The index of the first
774 duplicated block is FIRST_NEW_BLOCK. */
777 copy_phi_node_args (unsigned first_new_block
)
781 for (i
= first_new_block
; i
< (unsigned) last_basic_block_for_fn (cfun
); i
++)
782 BASIC_BLOCK_FOR_FN (cfun
, i
)->flags
|= BB_DUPLICATED
;
784 for (i
= first_new_block
; i
< (unsigned) last_basic_block_for_fn (cfun
); i
++)
785 add_phi_args_after_copy_bb (BASIC_BLOCK_FOR_FN (cfun
, i
));
787 for (i
= first_new_block
; i
< (unsigned) last_basic_block_for_fn (cfun
); i
++)
788 BASIC_BLOCK_FOR_FN (cfun
, i
)->flags
&= ~BB_DUPLICATED
;
792 /* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also
793 updates the PHI nodes at start of the copied region. In order to
794 achieve this, only loops whose exits all lead to the same location
797 Notice that we do not completely update the SSA web after
798 duplication. The caller is responsible for calling update_ssa
799 after the loop has been duplicated. */
802 gimple_duplicate_loop_to_header_edge (struct loop
*loop
, edge e
,
803 unsigned int ndupl
, sbitmap wont_exit
,
804 edge orig
, vec
<edge
> *to_remove
,
807 unsigned first_new_block
;
809 if (!loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES
))
811 if (!loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS
))
814 first_new_block
= last_basic_block_for_fn (cfun
);
815 if (!duplicate_loop_to_header_edge (loop
, e
, ndupl
, wont_exit
,
816 orig
, to_remove
, flags
))
819 /* Readd the removed phi args for e. */
820 flush_pending_stmts (e
);
822 /* Copy the phi node arguments. */
823 copy_phi_node_args (first_new_block
);
830 /* Returns true if we can unroll LOOP FACTOR times. Number
831 of iterations of the loop is returned in NITER. */
834 can_unroll_loop_p (struct loop
*loop
, unsigned factor
,
835 struct tree_niter_desc
*niter
)
839 /* Check whether unrolling is possible. We only want to unroll loops
840 for that we are able to determine number of iterations. We also
841 want to split the extra iterations of the loop from its end,
842 therefore we require that the loop has precisely one
845 exit
= single_dom_exit (loop
);
849 if (!number_of_iterations_exit (loop
, exit
, niter
, false)
850 || niter
->cmp
== ERROR_MARK
851 /* Scalar evolutions analysis might have copy propagated
852 the abnormal ssa names into these expressions, hence
853 emitting the computations based on them during loop
854 unrolling might create overlapping life ranges for
855 them, and failures in out-of-ssa. */
856 || contains_abnormal_ssa_name_p (niter
->may_be_zero
)
857 || contains_abnormal_ssa_name_p (niter
->control
.base
)
858 || contains_abnormal_ssa_name_p (niter
->control
.step
)
859 || contains_abnormal_ssa_name_p (niter
->bound
))
862 /* And of course, we must be able to duplicate the loop. */
863 if (!can_duplicate_loop_p (loop
))
866 /* The final loop should be small enough. */
867 if (tree_num_loop_insns (loop
, &eni_size_weights
) * factor
868 > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS
))
874 /* Determines the conditions that control execution of LOOP unrolled FACTOR
875 times. DESC is number of iterations of LOOP. ENTER_COND is set to
876 condition that must be true if the main loop can be entered.
877 EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing
878 how the exit from the unrolled loop should be controlled. */
881 determine_exit_conditions (struct loop
*loop
, struct tree_niter_desc
*desc
,
882 unsigned factor
, tree
*enter_cond
,
883 tree
*exit_base
, tree
*exit_step
,
884 enum tree_code
*exit_cmp
, tree
*exit_bound
)
887 tree base
= desc
->control
.base
;
888 tree step
= desc
->control
.step
;
889 tree bound
= desc
->bound
;
890 tree type
= TREE_TYPE (step
);
892 tree min
= lower_bound_in_type (type
, type
);
893 tree max
= upper_bound_in_type (type
, type
);
894 enum tree_code cmp
= desc
->cmp
;
895 tree cond
= boolean_true_node
, assum
;
897 /* For pointers, do the arithmetics in the type of step. */
898 base
= fold_convert (type
, base
);
899 bound
= fold_convert (type
, bound
);
901 *enter_cond
= boolean_false_node
;
902 *exit_base
= NULL_TREE
;
903 *exit_step
= NULL_TREE
;
904 *exit_cmp
= ERROR_MARK
;
905 *exit_bound
= NULL_TREE
;
906 gcc_assert (cmp
!= ERROR_MARK
);
908 /* We only need to be correct when we answer question
909 "Do at least FACTOR more iterations remain?" in the unrolled loop.
910 Thus, transforming BASE + STEP * i <> BOUND to
911 BASE + STEP * i < BOUND is ok. */
914 if (tree_int_cst_sign_bit (step
))
919 else if (cmp
== LT_EXPR
)
921 gcc_assert (!tree_int_cst_sign_bit (step
));
923 else if (cmp
== GT_EXPR
)
925 gcc_assert (tree_int_cst_sign_bit (step
));
930 /* The main body of the loop may be entered iff:
932 1) desc->may_be_zero is false.
933 2) it is possible to check that there are at least FACTOR iterations
934 of the loop, i.e., BOUND - step * FACTOR does not overflow.
935 3) # of iterations is at least FACTOR */
937 if (!integer_zerop (desc
->may_be_zero
))
938 cond
= fold_build2 (TRUTH_AND_EXPR
, boolean_type_node
,
939 invert_truthvalue (desc
->may_be_zero
),
942 bigstep
= fold_build2 (MULT_EXPR
, type
, step
,
943 build_int_cst_type (type
, factor
));
944 delta
= fold_build2 (MINUS_EXPR
, type
, bigstep
, step
);
946 assum
= fold_build2 (GE_EXPR
, boolean_type_node
,
948 fold_build2 (PLUS_EXPR
, type
, min
, delta
));
950 assum
= fold_build2 (LE_EXPR
, boolean_type_node
,
952 fold_build2 (PLUS_EXPR
, type
, max
, delta
));
953 cond
= fold_build2 (TRUTH_AND_EXPR
, boolean_type_node
, assum
, cond
);
955 bound
= fold_build2 (MINUS_EXPR
, type
, bound
, delta
);
956 assum
= fold_build2 (cmp
, boolean_type_node
, base
, bound
);
957 cond
= fold_build2 (TRUTH_AND_EXPR
, boolean_type_node
, assum
, cond
);
959 cond
= force_gimple_operand (unshare_expr (cond
), &stmts
, false, NULL_TREE
);
961 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
962 /* cond now may be a gimple comparison, which would be OK, but also any
963 other gimple rhs (say a && b). In this case we need to force it to
965 if (!is_gimple_condexpr (cond
))
967 cond
= force_gimple_operand (cond
, &stmts
, true, NULL_TREE
);
969 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
973 base
= force_gimple_operand (unshare_expr (base
), &stmts
, true, NULL_TREE
);
975 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
976 bound
= force_gimple_operand (unshare_expr (bound
), &stmts
, true, NULL_TREE
);
978 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
981 *exit_step
= bigstep
;
986 /* Scales the frequencies of all basic blocks in LOOP that are strictly
987 dominated by BB by NUM/DEN. */
990 scale_dominated_blocks_in_loop (struct loop
*loop
, basic_block bb
,
998 for (son
= first_dom_son (CDI_DOMINATORS
, bb
);
1000 son
= next_dom_son (CDI_DOMINATORS
, son
))
1002 if (!flow_bb_inside_loop_p (loop
, son
))
1004 scale_bbs_frequencies_int (&son
, 1, num
, den
);
1005 scale_dominated_blocks_in_loop (loop
, son
, num
, den
);
1009 /* Unroll LOOP FACTOR times. DESC describes number of iterations of LOOP.
1010 EXIT is the exit of the loop to that DESC corresponds.
1012 If N is number of iterations of the loop and MAY_BE_ZERO is the condition
1013 under that loop exits in the first iteration even if N != 0,
1017 x = phi (init, next);
1025 becomes (with possibly the exit conditions formulated a bit differently,
1026 avoiding the need to create a new iv):
1028 if (MAY_BE_ZERO || N < FACTOR)
1033 x = phi (init, next);
1044 } while (N >= FACTOR);
1047 init' = phi (init, x);
1051 x = phi (init', next);
1059 Before the loop is unrolled, TRANSFORM is called for it (only for the
1060 unrolled loop, but not for its versioned copy). DATA is passed to
1063 /* Probability in % that the unrolled loop is entered. Just a guess. */
1064 #define PROB_UNROLLED_LOOP_ENTERED 90
1067 tree_transform_and_unroll_loop (struct loop
*loop
, unsigned factor
,
1068 edge exit
, struct tree_niter_desc
*desc
,
1069 transform_callback transform
,
1073 tree ctr_before
, ctr_after
;
1074 tree enter_main_cond
, exit_base
, exit_step
, exit_bound
;
1075 enum tree_code exit_cmp
;
1076 gphi
*phi_old_loop
, *phi_new_loop
, *phi_rest
;
1077 gphi_iterator psi_old_loop
, psi_new_loop
;
1078 tree init
, next
, new_init
;
1079 struct loop
*new_loop
;
1080 basic_block rest
, exit_bb
;
1081 edge old_entry
, new_entry
, old_latch
, precond_edge
, new_exit
;
1082 edge new_nonexit
, e
;
1083 gimple_stmt_iterator bsi
;
1086 unsigned est_niter
, prob_entry
, scale_unrolled
, scale_rest
, freq_e
, freq_h
;
1087 unsigned new_est_niter
, i
, prob
;
1088 unsigned irr
= loop_preheader_edge (loop
)->flags
& EDGE_IRREDUCIBLE_LOOP
;
1090 auto_vec
<edge
> to_remove
;
1092 est_niter
= expected_loop_iterations (loop
);
1093 determine_exit_conditions (loop
, desc
, factor
,
1094 &enter_main_cond
, &exit_base
, &exit_step
,
1095 &exit_cmp
, &exit_bound
);
1097 /* Let us assume that the unrolled loop is quite likely to be entered. */
1098 if (integer_nonzerop (enter_main_cond
))
1099 prob_entry
= REG_BR_PROB_BASE
;
1101 prob_entry
= PROB_UNROLLED_LOOP_ENTERED
* REG_BR_PROB_BASE
/ 100;
1103 /* The values for scales should keep profile consistent, and somewhat close
1106 TODO: The current value of SCALE_REST makes it appear that the loop that
1107 is created by splitting the remaining iterations of the unrolled loop is
1108 executed the same number of times as the original loop, and with the same
1109 frequencies, which is obviously wrong. This does not appear to cause
1110 problems, so we do not bother with fixing it for now. To make the profile
1111 correct, we would need to change the probability of the exit edge of the
1112 loop, and recompute the distribution of frequencies in its body because
1113 of this change (scale the frequencies of blocks before and after the exit
1114 by appropriate factors). */
1115 scale_unrolled
= prob_entry
;
1116 scale_rest
= REG_BR_PROB_BASE
;
1118 new_loop
= loop_version (loop
, enter_main_cond
, NULL
,
1119 prob_entry
, scale_unrolled
, scale_rest
, true);
1120 gcc_assert (new_loop
!= NULL
);
1121 update_ssa (TODO_update_ssa
);
1123 /* Determine the probability of the exit edge of the unrolled loop. */
1124 new_est_niter
= est_niter
/ factor
;
1126 /* Without profile feedback, loops for that we do not know a better estimate
1127 are assumed to roll 10 times. When we unroll such loop, it appears to
1128 roll too little, and it may even seem to be cold. To avoid this, we
1129 ensure that the created loop appears to roll at least 5 times (but at
1130 most as many times as before unrolling). */
1131 if (new_est_niter
< 5)
1134 new_est_niter
= est_niter
;
1139 /* Prepare the cfg and update the phi nodes. Move the loop exit to the
1140 loop latch (and make its condition dummy, for the moment). */
1141 rest
= loop_preheader_edge (new_loop
)->src
;
1142 precond_edge
= single_pred_edge (rest
);
1143 split_edge (loop_latch_edge (loop
));
1144 exit_bb
= single_pred (loop
->latch
);
1146 /* Since the exit edge will be removed, the frequency of all the blocks
1147 in the loop that are dominated by it must be scaled by
1148 1 / (1 - exit->probability). */
1149 scale_dominated_blocks_in_loop (loop
, exit
->src
,
1151 REG_BR_PROB_BASE
- exit
->probability
);
1153 bsi
= gsi_last_bb (exit_bb
);
1154 exit_if
= gimple_build_cond (EQ_EXPR
, integer_zero_node
,
1156 NULL_TREE
, NULL_TREE
);
1158 gsi_insert_after (&bsi
, exit_if
, GSI_NEW_STMT
);
1159 new_exit
= make_edge (exit_bb
, rest
, EDGE_FALSE_VALUE
| irr
);
1160 rescan_loop_exit (new_exit
, true, false);
1162 /* Set the probability of new exit to the same of the old one. Fix
1163 the frequency of the latch block, by scaling it back by
1164 1 - exit->probability. */
1165 new_exit
->count
= exit
->count
;
1166 new_exit
->probability
= exit
->probability
;
1167 new_nonexit
= single_pred_edge (loop
->latch
);
1168 new_nonexit
->probability
= REG_BR_PROB_BASE
- exit
->probability
;
1169 new_nonexit
->flags
= EDGE_TRUE_VALUE
;
1170 new_nonexit
->count
-= exit
->count
;
1171 if (new_nonexit
->count
< 0)
1172 new_nonexit
->count
= 0;
1173 scale_bbs_frequencies_int (&loop
->latch
, 1, new_nonexit
->probability
,
1176 old_entry
= loop_preheader_edge (loop
);
1177 new_entry
= loop_preheader_edge (new_loop
);
1178 old_latch
= loop_latch_edge (loop
);
1179 for (psi_old_loop
= gsi_start_phis (loop
->header
),
1180 psi_new_loop
= gsi_start_phis (new_loop
->header
);
1181 !gsi_end_p (psi_old_loop
);
1182 gsi_next (&psi_old_loop
), gsi_next (&psi_new_loop
))
1184 phi_old_loop
= psi_old_loop
.phi ();
1185 phi_new_loop
= psi_new_loop
.phi ();
1187 init
= PHI_ARG_DEF_FROM_EDGE (phi_old_loop
, old_entry
);
1188 op
= PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop
, new_entry
);
1189 gcc_assert (operand_equal_for_phi_arg_p (init
, USE_FROM_PTR (op
)));
1190 next
= PHI_ARG_DEF_FROM_EDGE (phi_old_loop
, old_latch
);
1192 /* Prefer using original variable as a base for the new ssa name.
1193 This is necessary for virtual ops, and useful in order to avoid
1194 losing debug info for real ops. */
1195 if (TREE_CODE (next
) == SSA_NAME
1196 && useless_type_conversion_p (TREE_TYPE (next
),
1198 new_init
= copy_ssa_name (next
);
1199 else if (TREE_CODE (init
) == SSA_NAME
1200 && useless_type_conversion_p (TREE_TYPE (init
),
1202 new_init
= copy_ssa_name (init
);
1203 else if (useless_type_conversion_p (TREE_TYPE (next
), TREE_TYPE (init
)))
1204 new_init
= make_temp_ssa_name (TREE_TYPE (next
), NULL
, "unrinittmp");
1206 new_init
= make_temp_ssa_name (TREE_TYPE (init
), NULL
, "unrinittmp");
1208 phi_rest
= create_phi_node (new_init
, rest
);
1210 add_phi_arg (phi_rest
, init
, precond_edge
, UNKNOWN_LOCATION
);
1211 add_phi_arg (phi_rest
, next
, new_exit
, UNKNOWN_LOCATION
);
1212 SET_USE (op
, new_init
);
1217 /* Transform the loop. */
1219 (*transform
) (loop
, data
);
1221 /* Unroll the loop and remove the exits in all iterations except for the
1223 wont_exit
= sbitmap_alloc (factor
);
1224 bitmap_ones (wont_exit
);
1225 bitmap_clear_bit (wont_exit
, factor
- 1);
1227 ok
= gimple_duplicate_loop_to_header_edge
1228 (loop
, loop_latch_edge (loop
), factor
- 1,
1229 wont_exit
, new_exit
, &to_remove
, DLTHE_FLAG_UPDATE_FREQ
);
1233 FOR_EACH_VEC_ELT (to_remove
, i
, e
)
1235 ok
= remove_path (e
);
1238 update_ssa (TODO_update_ssa
);
1240 /* Ensure that the frequencies in the loop match the new estimated
1241 number of iterations, and change the probability of the new
1243 freq_h
= loop
->header
->frequency
;
1244 freq_e
= EDGE_FREQUENCY (loop_preheader_edge (loop
));
1246 scale_loop_frequencies (loop
, freq_e
* (new_est_niter
+ 1), freq_h
);
1248 exit_bb
= single_pred (loop
->latch
);
1249 new_exit
= find_edge (exit_bb
, rest
);
1250 new_exit
->count
= loop_preheader_edge (loop
)->count
;
1251 new_exit
->probability
= REG_BR_PROB_BASE
/ (new_est_niter
+ 1);
1253 rest
->count
+= new_exit
->count
;
1254 rest
->frequency
+= EDGE_FREQUENCY (new_exit
);
1256 new_nonexit
= single_pred_edge (loop
->latch
);
1257 prob
= new_nonexit
->probability
;
1258 new_nonexit
->probability
= REG_BR_PROB_BASE
- new_exit
->probability
;
1259 new_nonexit
->count
= exit_bb
->count
- new_exit
->count
;
1260 if (new_nonexit
->count
< 0)
1261 new_nonexit
->count
= 0;
1263 scale_bbs_frequencies_int (&loop
->latch
, 1, new_nonexit
->probability
,
1266 /* Finally create the new counter for number of iterations and add the new
1267 exit instruction. */
1268 bsi
= gsi_last_nondebug_bb (exit_bb
);
1269 exit_if
= as_a
<gcond
*> (gsi_stmt (bsi
));
1270 create_iv (exit_base
, exit_step
, NULL_TREE
, loop
,
1271 &bsi
, false, &ctr_before
, &ctr_after
);
1272 gimple_cond_set_code (exit_if
, exit_cmp
);
1273 gimple_cond_set_lhs (exit_if
, ctr_after
);
1274 gimple_cond_set_rhs (exit_if
, exit_bound
);
1275 update_stmt (exit_if
);
1277 #ifdef ENABLE_CHECKING
1278 verify_flow_info ();
1279 verify_loop_structure ();
1280 verify_loop_closed_ssa (true);
1284 /* Wrapper over tree_transform_and_unroll_loop for case we do not
1285 want to transform the loop before unrolling. The meaning
1286 of the arguments is the same as for tree_transform_and_unroll_loop. */
1289 tree_unroll_loop (struct loop
*loop
, unsigned factor
,
1290 edge exit
, struct tree_niter_desc
*desc
)
1292 tree_transform_and_unroll_loop (loop
, factor
, exit
, desc
,
1296 /* Rewrite the phi node at position PSI in function of the main
1297 induction variable MAIN_IV and insert the generated code at GSI. */
1300 rewrite_phi_with_iv (loop_p loop
,
1302 gimple_stmt_iterator
*gsi
,
1307 gphi
*phi
= psi
->phi ();
1308 tree atype
, mtype
, val
, res
= PHI_RESULT (phi
);
1310 if (virtual_operand_p (res
) || res
== main_iv
)
1316 if (!simple_iv (loop
, loop
, res
, &iv
, true))
1322 remove_phi_node (psi
, false);
1324 atype
= TREE_TYPE (res
);
1325 mtype
= POINTER_TYPE_P (atype
) ? sizetype
: atype
;
1326 val
= fold_build2 (MULT_EXPR
, mtype
, unshare_expr (iv
.step
),
1327 fold_convert (mtype
, main_iv
));
1328 val
= fold_build2 (POINTER_TYPE_P (atype
)
1329 ? POINTER_PLUS_EXPR
: PLUS_EXPR
,
1330 atype
, unshare_expr (iv
.base
), val
);
1331 val
= force_gimple_operand_gsi (gsi
, val
, false, NULL_TREE
, true,
1333 stmt
= gimple_build_assign (res
, val
);
1334 gsi_insert_before (gsi
, stmt
, GSI_SAME_STMT
);
1337 /* Rewrite all the phi nodes of LOOP in function of the main induction
1338 variable MAIN_IV. */
1341 rewrite_all_phi_nodes_with_iv (loop_p loop
, tree main_iv
)
1344 basic_block
*bbs
= get_loop_body_in_dom_order (loop
);
1347 for (i
= 0; i
< loop
->num_nodes
; i
++)
1349 basic_block bb
= bbs
[i
];
1350 gimple_stmt_iterator gsi
= gsi_after_labels (bb
);
1352 if (bb
->loop_father
!= loop
)
1355 for (psi
= gsi_start_phis (bb
); !gsi_end_p (psi
); )
1356 rewrite_phi_with_iv (loop
, &psi
, &gsi
, main_iv
);
1362 /* Bases all the induction variables in LOOP on a single induction variable
1363 (with base 0 and step 1), whose final value is compared with *NIT. When the
1364 IV type precision has to be larger than *NIT type precision, *NIT is
1365 converted to the larger type, the conversion code is inserted before the
1366 loop, and *NIT is updated to the new definition. When BUMP_IN_LATCH is true,
1367 the induction variable is incremented in the loop latch, otherwise it is
1368 incremented in the loop header. Return the induction variable that was
1372 canonicalize_loop_ivs (struct loop
*loop
, tree
*nit
, bool bump_in_latch
)
1374 unsigned precision
= TYPE_PRECISION (TREE_TYPE (*nit
));
1375 unsigned original_precision
= precision
;
1376 tree type
, var_before
;
1377 gimple_stmt_iterator gsi
;
1380 edge exit
= single_dom_exit (loop
);
1383 bool unsigned_p
= false;
1385 for (psi
= gsi_start_phis (loop
->header
);
1386 !gsi_end_p (psi
); gsi_next (&psi
))
1388 gphi
*phi
= psi
.phi ();
1389 tree res
= PHI_RESULT (phi
);
1392 type
= TREE_TYPE (res
);
1393 if (virtual_operand_p (res
)
1394 || (!INTEGRAL_TYPE_P (type
)
1395 && !POINTER_TYPE_P (type
))
1396 || TYPE_PRECISION (type
) < precision
)
1399 uns
= POINTER_TYPE_P (type
) | TYPE_UNSIGNED (type
);
1401 if (TYPE_PRECISION (type
) > precision
)
1406 precision
= TYPE_PRECISION (type
);
1409 mode
= smallest_mode_for_size (precision
, MODE_INT
);
1410 precision
= GET_MODE_PRECISION (mode
);
1411 type
= build_nonstandard_integer_type (precision
, unsigned_p
);
1413 if (original_precision
!= precision
)
1415 *nit
= fold_convert (type
, *nit
);
1416 *nit
= force_gimple_operand (*nit
, &stmts
, true, NULL_TREE
);
1418 gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
1422 gsi
= gsi_last_bb (loop
->latch
);
1424 gsi
= gsi_last_nondebug_bb (loop
->header
);
1425 create_iv (build_int_cst_type (type
, 0), build_int_cst (type
, 1), NULL_TREE
,
1426 loop
, &gsi
, bump_in_latch
, &var_before
, NULL
);
1428 rewrite_all_phi_nodes_with_iv (loop
, var_before
);
1430 stmt
= as_a
<gcond
*> (last_stmt (exit
->src
));
1431 /* Make the loop exit if the control condition is not satisfied. */
1432 if (exit
->flags
& EDGE_TRUE_VALUE
)
1436 extract_true_false_edges_from_block (exit
->src
, &te
, &fe
);
1437 te
->flags
= EDGE_FALSE_VALUE
;
1438 fe
->flags
= EDGE_TRUE_VALUE
;
1440 gimple_cond_set_code (stmt
, LT_EXPR
);
1441 gimple_cond_set_lhs (stmt
, var_before
);
1442 gimple_cond_set_rhs (stmt
, *nit
);