1 /* High-level loop manipulation functions.
2 Copyright (C) 2004, 2005 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 2, 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 COPYING. If not, write to the Free
18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
23 #include "coretypes.h"
28 #include "hard-reg-set.h"
29 #include "basic-block.h"
31 #include "diagnostic.h"
32 #include "tree-flow.h"
33 #include "tree-dump.h"
36 #include "tree-pass.h"
37 #include "cfglayout.h"
38 #include "tree-scalar-evolution.h"
41 /* Creates an induction variable with value BASE + STEP * iteration in LOOP.
42 It is expected that neither BASE nor STEP are shared with other expressions
43 (unless the sharing rules allow this). Use VAR as a base var_decl for it
44 (if NULL, a new temporary will be created). The increment will occur at
45 INCR_POS (after it if AFTER is true, before it otherwise). INCR_POS and
46 AFTER can be computed using standard_iv_increment_position. The ssa versions
47 of the variable before and after increment will be stored in VAR_BEFORE and
48 VAR_AFTER (unless they are NULL). */
51 create_iv (tree base
, tree step
, tree var
, struct loop
*loop
,
52 block_stmt_iterator
*incr_pos
, bool after
,
53 tree
*var_before
, tree
*var_after
)
55 tree stmt
, initial
, step1
, stmts
;
57 enum tree_code incr_op
= PLUS_EXPR
;
58 edge pe
= loop_preheader_edge (loop
);
62 var
= create_tmp_var (TREE_TYPE (base
), "ivtmp");
63 add_referenced_var (var
);
66 vb
= make_ssa_name (var
, NULL_TREE
);
69 va
= make_ssa_name (var
, NULL_TREE
);
73 /* For easier readability of the created code, produce MINUS_EXPRs
75 if (TREE_CODE (step
) == INTEGER_CST
)
77 if (TYPE_UNSIGNED (TREE_TYPE (step
)))
79 step1
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (step
), step
);
80 if (tree_int_cst_lt (step1
, step
))
88 if (!tree_expr_nonnegative_p (step
)
89 && may_negate_without_overflow_p (step
))
92 step
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (step
), step
);
97 /* Gimplify the step if necessary. We put the computations in front of the
98 loop (i.e. the step should be loop invariant). */
99 step
= force_gimple_operand (step
, &stmts
, true, var
);
101 bsi_insert_on_edge_immediate (pe
, stmts
);
103 stmt
= build2 (MODIFY_EXPR
, void_type_node
, va
,
104 build2 (incr_op
, TREE_TYPE (base
),
106 SSA_NAME_DEF_STMT (va
) = stmt
;
108 bsi_insert_after (incr_pos
, stmt
, BSI_NEW_STMT
);
110 bsi_insert_before (incr_pos
, stmt
, BSI_NEW_STMT
);
112 initial
= force_gimple_operand (base
, &stmts
, true, var
);
114 bsi_insert_on_edge_immediate (pe
, stmts
);
116 stmt
= create_phi_node (vb
, loop
->header
);
117 SSA_NAME_DEF_STMT (vb
) = stmt
;
118 add_phi_arg (stmt
, initial
, loop_preheader_edge (loop
));
119 add_phi_arg (stmt
, va
, loop_latch_edge (loop
));
122 /* Add exit phis for the USE on EXIT. */
125 add_exit_phis_edge (basic_block exit
, tree use
)
127 tree phi
, def_stmt
= SSA_NAME_DEF_STMT (use
);
128 basic_block def_bb
= bb_for_stmt (def_stmt
);
129 struct loop
*def_loop
;
133 /* Check that some of the edges entering the EXIT block exits a loop in
134 that USE is defined. */
135 FOR_EACH_EDGE (e
, ei
, exit
->preds
)
137 def_loop
= find_common_loop (def_bb
->loop_father
, e
->src
->loop_father
);
138 if (!flow_bb_inside_loop_p (def_loop
, e
->dest
))
145 phi
= create_phi_node (use
, exit
);
146 create_new_def_for (PHI_RESULT (phi
), phi
, PHI_RESULT_PTR (phi
));
147 FOR_EACH_EDGE (e
, ei
, exit
->preds
)
148 add_phi_arg (phi
, use
, e
);
151 /* Add exit phis for VAR that is used in LIVEIN.
152 Exits of the loops are stored in EXITS. */
155 add_exit_phis_var (tree var
, bitmap livein
, bitmap exits
)
159 basic_block def_bb
= bb_for_stmt (SSA_NAME_DEF_STMT (var
));
162 if (is_gimple_reg (var
))
163 bitmap_clear_bit (livein
, def_bb
->index
);
165 bitmap_set_bit (livein
, def_bb
->index
);
167 def
= BITMAP_ALLOC (NULL
);
168 bitmap_set_bit (def
, def_bb
->index
);
169 compute_global_livein (livein
, def
);
172 EXECUTE_IF_AND_IN_BITMAP (exits
, livein
, 0, index
, bi
)
174 add_exit_phis_edge (BASIC_BLOCK (index
), var
);
178 /* Add exit phis for the names marked in NAMES_TO_RENAME.
179 Exits of the loops are stored in EXITS. Sets of blocks where the ssa
180 names are used are stored in USE_BLOCKS. */
183 add_exit_phis (bitmap names_to_rename
, bitmap
*use_blocks
, bitmap loop_exits
)
188 EXECUTE_IF_SET_IN_BITMAP (names_to_rename
, 0, i
, bi
)
190 add_exit_phis_var (ssa_name (i
), use_blocks
[i
], loop_exits
);
194 /* Returns a bitmap of all loop exit edge targets. */
197 get_loops_exits (void)
199 bitmap exits
= BITMAP_ALLOC (NULL
);
206 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
207 if (e
->src
!= ENTRY_BLOCK_PTR
208 && !flow_bb_inside_loop_p (e
->src
->loop_father
, bb
))
210 bitmap_set_bit (exits
, bb
->index
);
218 /* For USE in BB, if it is used outside of the loop it is defined in,
219 mark it for rewrite. Record basic block BB where it is used
220 to USE_BLOCKS. Record the ssa name index to NEED_PHIS bitmap. */
223 find_uses_to_rename_use (basic_block bb
, tree use
, bitmap
*use_blocks
,
228 struct loop
*def_loop
;
230 if (TREE_CODE (use
) != SSA_NAME
)
233 /* We don't need to keep virtual operands in loop-closed form. */
234 if (!is_gimple_reg (use
))
237 ver
= SSA_NAME_VERSION (use
);
238 def_bb
= bb_for_stmt (SSA_NAME_DEF_STMT (use
));
241 def_loop
= def_bb
->loop_father
;
243 /* If the definition is not inside loop, it is not interesting. */
244 if (!def_loop
->outer
)
247 if (!use_blocks
[ver
])
248 use_blocks
[ver
] = BITMAP_ALLOC (NULL
);
249 bitmap_set_bit (use_blocks
[ver
], bb
->index
);
251 bitmap_set_bit (need_phis
, ver
);
254 /* For uses in STMT, mark names that are used outside of the loop they are
255 defined to rewrite. Record the set of blocks in that the ssa
256 names are defined to USE_BLOCKS and the ssa names themselves to
260 find_uses_to_rename_stmt (tree stmt
, bitmap
*use_blocks
, bitmap need_phis
)
264 basic_block bb
= bb_for_stmt (stmt
);
266 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_ALL_USES
| SSA_OP_ALL_KILLS
)
267 find_uses_to_rename_use (bb
, var
, use_blocks
, need_phis
);
270 /* Marks names that are used in BB and outside of the loop they are
271 defined in for rewrite. Records the set of blocks in that the ssa
272 names are defined to USE_BLOCKS. Record the SSA names that will
273 need exit PHIs in NEED_PHIS. */
276 find_uses_to_rename_bb (basic_block bb
, bitmap
*use_blocks
, bitmap need_phis
)
278 block_stmt_iterator bsi
;
283 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
284 for (phi
= phi_nodes (e
->dest
); phi
; phi
= PHI_CHAIN (phi
))
285 find_uses_to_rename_use (bb
, PHI_ARG_DEF_FROM_EDGE (phi
, e
),
286 use_blocks
, need_phis
);
288 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
289 find_uses_to_rename_stmt (bsi_stmt (bsi
), use_blocks
, need_phis
);
292 /* Marks names that are used outside of the loop they are defined in
293 for rewrite. Records the set of blocks in that the ssa
294 names are defined to USE_BLOCKS. If CHANGED_BBS is not NULL,
295 scan only blocks in this set. */
298 find_uses_to_rename (bitmap changed_bbs
, bitmap
*use_blocks
, bitmap need_phis
)
304 if (changed_bbs
&& !bitmap_empty_p (changed_bbs
))
306 EXECUTE_IF_SET_IN_BITMAP (changed_bbs
, 0, index
, bi
)
308 find_uses_to_rename_bb (BASIC_BLOCK (index
), use_blocks
, need_phis
);
315 find_uses_to_rename_bb (bb
, use_blocks
, need_phis
);
320 /* Rewrites the program into a loop closed ssa form -- i.e. inserts extra
321 phi nodes to ensure that no variable is used outside the loop it is
324 This strengthening of the basic ssa form has several advantages:
326 1) Updating it during unrolling/peeling/versioning is trivial, since
327 we do not need to care about the uses outside of the loop.
328 2) The behavior of all uses of an induction variable is the same.
329 Without this, you need to distinguish the case when the variable
330 is used outside of the loop it is defined in, for example
332 for (i = 0; i < 100; i++)
334 for (j = 0; j < 100; j++)
342 Looking from the outer loop with the normal SSA form, the first use of k
343 is not well-behaved, while the second one is an induction variable with
346 If CHANGED_BBS is not NULL, we look for uses outside loops only in
347 the basic blocks in this set.
349 UPDATE_FLAG is used in the call to update_ssa. See
350 TODO_update_ssa* for documentation. */
353 rewrite_into_loop_closed_ssa (bitmap changed_bbs
, unsigned update_flag
)
355 bitmap loop_exits
= get_loops_exits ();
357 unsigned i
, old_num_ssa_names
;
358 bitmap names_to_rename
= BITMAP_ALLOC (NULL
);
360 /* If the pass has caused the SSA form to be out-of-date, update it
362 update_ssa (update_flag
);
364 old_num_ssa_names
= num_ssa_names
;
365 use_blocks
= XCNEWVEC (bitmap
, old_num_ssa_names
);
367 /* Find the uses outside loops. */
368 find_uses_to_rename (changed_bbs
, use_blocks
, names_to_rename
);
370 /* Add the PHI nodes on exits of the loops for the names we need to
372 add_exit_phis (names_to_rename
, use_blocks
, loop_exits
);
374 for (i
= 0; i
< old_num_ssa_names
; i
++)
375 BITMAP_FREE (use_blocks
[i
]);
377 BITMAP_FREE (loop_exits
);
378 BITMAP_FREE (names_to_rename
);
380 /* Fix up all the names found to be used outside their original
382 update_ssa (TODO_update_ssa
);
385 /* Check invariants of the loop closed ssa form for the USE in BB. */
388 check_loop_closed_ssa_use (basic_block bb
, tree use
)
393 if (TREE_CODE (use
) != SSA_NAME
|| !is_gimple_reg (use
))
396 def
= SSA_NAME_DEF_STMT (use
);
397 def_bb
= bb_for_stmt (def
);
399 || flow_bb_inside_loop_p (def_bb
->loop_father
, bb
));
402 /* Checks invariants of loop closed ssa form in statement STMT in BB. */
405 check_loop_closed_ssa_stmt (basic_block bb
, tree stmt
)
410 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_ALL_USES
| SSA_OP_ALL_KILLS
)
411 check_loop_closed_ssa_use (bb
, var
);
414 /* Checks that invariants of the loop closed ssa form are preserved. */
417 verify_loop_closed_ssa (void)
420 block_stmt_iterator bsi
;
424 if (current_loops
== NULL
)
431 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
432 for (i
= 0; i
< (unsigned) PHI_NUM_ARGS (phi
); i
++)
433 check_loop_closed_ssa_use (PHI_ARG_EDGE (phi
, i
)->src
,
434 PHI_ARG_DEF (phi
, i
));
436 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
437 check_loop_closed_ssa_stmt (bb
, bsi_stmt (bsi
));
441 /* Split loop exit edge EXIT. The things are a bit complicated by a need to
442 preserve the loop closed ssa form. */
445 split_loop_exit_edge (edge exit
)
447 basic_block dest
= exit
->dest
;
448 basic_block bb
= split_edge (exit
);
449 tree phi
, new_phi
, new_name
, name
;
452 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
454 op_p
= PHI_ARG_DEF_PTR_FROM_EDGE (phi
, single_succ_edge (bb
));
456 name
= USE_FROM_PTR (op_p
);
458 /* If the argument of the phi node is a constant, we do not need
459 to keep it inside loop. */
460 if (TREE_CODE (name
) != SSA_NAME
)
463 /* Otherwise create an auxiliary phi node that will copy the value
464 of the ssa name out of the loop. */
465 new_name
= duplicate_ssa_name (name
, NULL
);
466 new_phi
= create_phi_node (new_name
, bb
);
467 SSA_NAME_DEF_STMT (new_name
) = new_phi
;
468 add_phi_arg (new_phi
, name
, exit
);
469 SET_USE (op_p
, new_name
);
473 /* Returns the basic block in that statements should be emitted for induction
474 variables incremented at the end of the LOOP. */
477 ip_end_pos (struct loop
*loop
)
482 /* Returns the basic block in that statements should be emitted for induction
483 variables incremented just before exit condition of a LOOP. */
486 ip_normal_pos (struct loop
*loop
)
492 if (!single_pred_p (loop
->latch
))
495 bb
= single_pred (loop
->latch
);
496 last
= last_stmt (bb
);
497 if (TREE_CODE (last
) != COND_EXPR
)
500 exit
= EDGE_SUCC (bb
, 0);
501 if (exit
->dest
== loop
->latch
)
502 exit
= EDGE_SUCC (bb
, 1);
504 if (flow_bb_inside_loop_p (loop
, exit
->dest
))
510 /* Stores the standard position for induction variable increment in LOOP
511 (just before the exit condition if it is available and latch block is empty,
512 end of the latch block otherwise) to BSI. INSERT_AFTER is set to true if
513 the increment should be inserted after *BSI. */
516 standard_iv_increment_position (struct loop
*loop
, block_stmt_iterator
*bsi
,
519 basic_block bb
= ip_normal_pos (loop
), latch
= ip_end_pos (loop
);
520 tree last
= last_stmt (latch
);
523 || (last
&& TREE_CODE (last
) != LABEL_EXPR
))
525 *bsi
= bsi_last (latch
);
526 *insert_after
= true;
530 *bsi
= bsi_last (bb
);
531 *insert_after
= false;
535 /* Copies phi node arguments for duplicated blocks. The index of the first
536 duplicated block is FIRST_NEW_BLOCK. */
539 copy_phi_node_args (unsigned first_new_block
)
543 for (i
= first_new_block
; i
< (unsigned) last_basic_block
; i
++)
544 BASIC_BLOCK (i
)->flags
|= BB_DUPLICATED
;
546 for (i
= first_new_block
; i
< (unsigned) last_basic_block
; i
++)
547 add_phi_args_after_copy_bb (BASIC_BLOCK (i
));
549 for (i
= first_new_block
; i
< (unsigned) last_basic_block
; i
++)
550 BASIC_BLOCK (i
)->flags
&= ~BB_DUPLICATED
;
554 /* The same as cfgloopmanip.c:duplicate_loop_to_header_edge, but also
555 updates the PHI nodes at start of the copied region. In order to
556 achieve this, only loops whose exits all lead to the same location
559 Notice that we do not completely update the SSA web after
560 duplication. The caller is responsible for calling update_ssa
561 after the loop has been duplicated. */
564 tree_duplicate_loop_to_header_edge (struct loop
*loop
, edge e
,
566 unsigned int ndupl
, sbitmap wont_exit
,
567 edge orig
, edge
*to_remove
,
568 unsigned int *n_to_remove
, int flags
)
570 unsigned first_new_block
;
572 if (!(loops
->state
& LOOPS_HAVE_SIMPLE_LATCHES
))
574 if (!(loops
->state
& LOOPS_HAVE_PREHEADERS
))
577 #ifdef ENABLE_CHECKING
578 verify_loop_closed_ssa ();
581 first_new_block
= last_basic_block
;
582 if (!duplicate_loop_to_header_edge (loop
, e
, loops
, ndupl
, wont_exit
,
583 orig
, to_remove
, n_to_remove
, flags
))
586 /* Readd the removed phi args for e. */
587 flush_pending_stmts (e
);
589 /* Copy the phi node arguments. */
590 copy_phi_node_args (first_new_block
);
597 /* Build if (COND) goto THEN_LABEL; else goto ELSE_LABEL; */
600 build_if_stmt (tree cond
, tree then_label
, tree else_label
)
602 return build3 (COND_EXPR
, void_type_node
,
604 build1 (GOTO_EXPR
, void_type_node
, then_label
),
605 build1 (GOTO_EXPR
, void_type_node
, else_label
));
608 /* Returns true if we can unroll LOOP FACTOR times. Number
609 of iterations of the loop is returned in NITER. */
612 can_unroll_loop_p (struct loop
*loop
, unsigned factor
,
613 struct tree_niter_desc
*niter
)
617 /* Check whether unrolling is possible. We only want to unroll loops
618 for that we are able to determine number of iterations. We also
619 want to split the extra iterations of the loop from its end,
620 therefore we require that the loop has precisely one
623 exit
= single_dom_exit (loop
);
627 if (!number_of_iterations_exit (loop
, exit
, niter
, false)
628 || niter
->cmp
== ERROR_MARK
629 /* Scalar evolutions analysis might have copy propagated
630 the abnormal ssa names into these expressions, hence
631 emiting the computations based on them during loop
632 unrolling might create overlapping life ranges for
633 them, and failures in out-of-ssa. */
634 || contains_abnormal_ssa_name_p (niter
->may_be_zero
)
635 || contains_abnormal_ssa_name_p (niter
->control
.base
)
636 || contains_abnormal_ssa_name_p (niter
->control
.step
)
637 || contains_abnormal_ssa_name_p (niter
->bound
))
640 /* And of course, we must be able to duplicate the loop. */
641 if (!can_duplicate_loop_p (loop
))
644 /* The final loop should be small enough. */
645 if (tree_num_loop_insns (loop
) * factor
646 > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS
))
652 /* Determines the conditions that control execution of LOOP unrolled FACTOR
653 times. DESC is number of iterations of LOOP. ENTER_COND is set to
654 condition that must be true if the main loop can be entered.
655 EXIT_BASE, EXIT_STEP, EXIT_CMP and EXIT_BOUND are set to values describing
656 how the exit from the unrolled loop should be controlled. */
659 determine_exit_conditions (struct loop
*loop
, struct tree_niter_desc
*desc
,
660 unsigned factor
, tree
*enter_cond
,
661 tree
*exit_base
, tree
*exit_step
,
662 enum tree_code
*exit_cmp
, tree
*exit_bound
)
665 tree base
= desc
->control
.base
;
666 tree step
= desc
->control
.step
;
667 tree bound
= desc
->bound
;
668 tree type
= TREE_TYPE (base
);
670 tree min
= lower_bound_in_type (type
, type
);
671 tree max
= upper_bound_in_type (type
, type
);
672 enum tree_code cmp
= desc
->cmp
;
673 tree cond
= boolean_true_node
, assum
;
675 *enter_cond
= boolean_false_node
;
676 *exit_base
= NULL_TREE
;
677 *exit_step
= NULL_TREE
;
678 *exit_cmp
= ERROR_MARK
;
679 *exit_bound
= NULL_TREE
;
680 gcc_assert (cmp
!= ERROR_MARK
);
682 /* We only need to be correct when we answer question
683 "Do at least FACTOR more iterations remain?" in the unrolled loop.
684 Thus, transforming BASE + STEP * i <> BOUND to
685 BASE + STEP * i < BOUND is ok. */
688 if (tree_int_cst_sign_bit (step
))
693 else if (cmp
== LT_EXPR
)
695 gcc_assert (!tree_int_cst_sign_bit (step
));
697 else if (cmp
== GT_EXPR
)
699 gcc_assert (tree_int_cst_sign_bit (step
));
704 /* The main body of the loop may be entered iff:
706 1) desc->may_be_zero is false.
707 2) it is possible to check that there are at least FACTOR iterations
708 of the loop, i.e., BOUND - step * FACTOR does not overflow.
709 3) # of iterations is at least FACTOR */
711 if (!zero_p (desc
->may_be_zero
))
712 cond
= fold_build2 (TRUTH_AND_EXPR
, boolean_type_node
,
713 invert_truthvalue (desc
->may_be_zero
),
716 bigstep
= fold_build2 (MULT_EXPR
, type
, step
,
717 build_int_cst_type (type
, factor
));
718 delta
= fold_build2 (MINUS_EXPR
, type
, bigstep
, step
);
720 assum
= fold_build2 (GE_EXPR
, boolean_type_node
,
722 fold_build2 (PLUS_EXPR
, type
, min
, delta
));
724 assum
= fold_build2 (LE_EXPR
, boolean_type_node
,
726 fold_build2 (PLUS_EXPR
, type
, max
, delta
));
727 cond
= fold_build2 (TRUTH_AND_EXPR
, boolean_type_node
, assum
, cond
);
729 bound
= fold_build2 (MINUS_EXPR
, type
, bound
, delta
);
730 assum
= fold_build2 (cmp
, boolean_type_node
, base
, bound
);
731 cond
= fold_build2 (TRUTH_AND_EXPR
, boolean_type_node
, assum
, cond
);
733 cond
= force_gimple_operand (unshare_expr (cond
), &stmts
, false, NULL_TREE
);
735 bsi_insert_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
736 /* cond now may be a gimple comparison, which would be OK, but also any
737 other gimple rhs (say a && b). In this case we need to force it to
739 if (!is_gimple_condexpr (cond
))
741 cond
= force_gimple_operand (cond
, &stmts
, true, NULL_TREE
);
743 bsi_insert_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
747 base
= force_gimple_operand (unshare_expr (base
), &stmts
, true, NULL_TREE
);
749 bsi_insert_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
750 bound
= force_gimple_operand (unshare_expr (bound
), &stmts
, true, NULL_TREE
);
752 bsi_insert_on_edge_immediate (loop_preheader_edge (loop
), stmts
);
755 *exit_step
= bigstep
;
760 /* Unroll LOOP FACTOR times. LOOPS is the loops tree. DESC describes
761 number of iterations of LOOP. EXIT is the exit of the loop to that
764 If N is number of iterations of the loop and MAY_BE_ZERO is the condition
765 under that loop exits in the first iteration even if N != 0,
769 x = phi (init, next);
777 becomes (with possibly the exit conditions formulated a bit differently,
778 avoiding the need to create a new iv):
780 if (MAY_BE_ZERO || N < FACTOR)
785 x = phi (init, next);
796 } while (N >= FACTOR);
799 init' = phi (init, x);
803 x = phi (init', next);
812 tree_unroll_loop (struct loops
*loops
, struct loop
*loop
, unsigned factor
,
813 edge exit
, struct tree_niter_desc
*desc
)
815 tree dont_exit
, exit_if
, ctr_before
, ctr_after
;
816 tree enter_main_cond
, exit_base
, exit_step
, exit_bound
;
817 enum tree_code exit_cmp
;
818 tree phi_old_loop
, phi_new_loop
, phi_rest
, init
, next
, new_init
, var
;
819 struct loop
*new_loop
;
820 basic_block rest
, exit_bb
;
821 edge old_entry
, new_entry
, old_latch
, precond_edge
, new_exit
;
822 edge nonexit
, new_nonexit
;
823 block_stmt_iterator bsi
;
827 unsigned irr
= loop_preheader_edge (loop
)->flags
& EDGE_IRREDUCIBLE_LOOP
;
830 est_niter
= expected_loop_iterations (loop
);
831 determine_exit_conditions (loop
, desc
, factor
,
832 &enter_main_cond
, &exit_base
, &exit_step
,
833 &exit_cmp
, &exit_bound
);
835 new_loop
= loop_version (loops
, loop
, enter_main_cond
, NULL
, true);
836 gcc_assert (new_loop
!= NULL
);
837 update_ssa (TODO_update_ssa
);
839 /* Unroll the loop and remove the old exits. */
840 dont_exit
= ((exit
->flags
& EDGE_TRUE_VALUE
)
842 : boolean_true_node
);
843 if (exit
== EDGE_SUCC (exit
->src
, 0))
844 nonexit
= EDGE_SUCC (exit
->src
, 1);
846 nonexit
= EDGE_SUCC (exit
->src
, 0);
847 nonexit
->probability
= REG_BR_PROB_BASE
;
848 exit
->probability
= 0;
849 nonexit
->count
+= exit
->count
;
851 exit_if
= last_stmt (exit
->src
);
852 COND_EXPR_COND (exit_if
) = dont_exit
;
853 update_stmt (exit_if
);
855 wont_exit
= sbitmap_alloc (factor
);
856 sbitmap_ones (wont_exit
);
857 ok
= tree_duplicate_loop_to_header_edge
858 (loop
, loop_latch_edge (loop
), loops
, factor
- 1,
859 wont_exit
, NULL
, NULL
, NULL
, DLTHE_FLAG_UPDATE_FREQ
);
862 update_ssa (TODO_update_ssa
);
864 /* Prepare the cfg and update the phi nodes. */
865 rest
= loop_preheader_edge (new_loop
)->src
;
866 precond_edge
= single_pred_edge (rest
);
867 split_edge (loop_latch_edge (loop
));
868 exit_bb
= single_pred (loop
->latch
);
870 new_exit
= make_edge (exit_bb
, rest
, EDGE_FALSE_VALUE
| irr
);
871 new_exit
->count
= loop_preheader_edge (loop
)->count
;
872 est_niter
= est_niter
/ factor
+ 1;
873 new_exit
->probability
= REG_BR_PROB_BASE
/ est_niter
;
875 new_nonexit
= single_pred_edge (loop
->latch
);
876 new_nonexit
->flags
= EDGE_TRUE_VALUE
;
877 new_nonexit
->probability
= REG_BR_PROB_BASE
- new_exit
->probability
;
879 old_entry
= loop_preheader_edge (loop
);
880 new_entry
= loop_preheader_edge (new_loop
);
881 old_latch
= loop_latch_edge (loop
);
882 for (phi_old_loop
= phi_nodes (loop
->header
),
883 phi_new_loop
= phi_nodes (new_loop
->header
);
885 phi_old_loop
= PHI_CHAIN (phi_old_loop
),
886 phi_new_loop
= PHI_CHAIN (phi_new_loop
))
888 init
= PHI_ARG_DEF_FROM_EDGE (phi_old_loop
, old_entry
);
889 op
= PHI_ARG_DEF_PTR_FROM_EDGE (phi_new_loop
, new_entry
);
890 gcc_assert (operand_equal_for_phi_arg_p (init
, USE_FROM_PTR (op
)));
891 next
= PHI_ARG_DEF_FROM_EDGE (phi_old_loop
, old_latch
);
893 /* Prefer using original variable as a base for the new ssa name.
894 This is necessary for virtual ops, and useful in order to avoid
895 losing debug info for real ops. */
896 if (TREE_CODE (next
) == SSA_NAME
)
897 var
= SSA_NAME_VAR (next
);
898 else if (TREE_CODE (init
) == SSA_NAME
)
899 var
= SSA_NAME_VAR (init
);
902 var
= create_tmp_var (TREE_TYPE (init
), "unrinittmp");
903 add_referenced_var (var
);
906 new_init
= make_ssa_name (var
, NULL_TREE
);
907 phi_rest
= create_phi_node (new_init
, rest
);
908 SSA_NAME_DEF_STMT (new_init
) = phi_rest
;
910 add_phi_arg (phi_rest
, init
, precond_edge
);
911 add_phi_arg (phi_rest
, next
, new_exit
);
912 SET_USE (op
, new_init
);
915 /* Finally create the new counter for number of iterations and add the new
917 bsi
= bsi_last (exit_bb
);
918 create_iv (exit_base
, exit_step
, NULL_TREE
, loop
,
919 &bsi
, true, &ctr_before
, &ctr_after
);
920 exit_if
= build_if_stmt (build2 (exit_cmp
, boolean_type_node
, ctr_after
,
922 tree_block_label (loop
->latch
),
923 tree_block_label (rest
));
924 bsi_insert_after (&bsi
, exit_if
, BSI_NEW_STMT
);
926 #ifdef ENABLE_CHECKING
928 verify_dominators (CDI_DOMINATORS
);
929 verify_loop_structure (loops
);
930 verify_loop_closed_ssa ();