1 /* Optimization of PHI nodes by converting them into straightline code.
2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 3, or (at your option) any
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
29 #include "basic-block.h"
31 #include "tree-flow.h"
32 #include "tree-pass.h"
33 #include "tree-dump.h"
34 #include "langhooks.h"
35 #include "pointer-set.h"
38 #include "tree-data-ref.h"
39 #include "tree-pretty-print.h"
41 static unsigned int tree_ssa_phiopt (void);
42 static unsigned int tree_ssa_phiopt_worker (bool);
43 static bool conditional_replacement (basic_block
, basic_block
,
44 edge
, edge
, gimple
, tree
, tree
);
45 static int value_replacement (basic_block
, basic_block
,
46 edge
, edge
, gimple
, tree
, tree
);
47 static bool minmax_replacement (basic_block
, basic_block
,
48 edge
, edge
, gimple
, tree
, tree
);
49 static bool abs_replacement (basic_block
, basic_block
,
50 edge
, edge
, gimple
, tree
, tree
);
51 static bool cond_store_replacement (basic_block
, basic_block
, edge
, edge
,
52 struct pointer_set_t
*);
53 static bool cond_if_else_store_replacement (basic_block
, basic_block
, basic_block
);
54 static struct pointer_set_t
* get_non_trapping (void);
55 static void replace_phi_edge_with_variable (basic_block
, edge
, gimple
, tree
);
57 /* This pass tries to replaces an if-then-else block with an
58 assignment. We have four kinds of transformations. Some of these
59 transformations are also performed by the ifcvt RTL optimizer.
61 Conditional Replacement
62 -----------------------
64 This transformation, implemented in conditional_replacement,
68 if (cond) goto bb2; else goto bb1;
71 x = PHI <0 (bb1), 1 (bb0), ...>;
79 x = PHI <x' (bb0), ...>;
81 We remove bb1 as it becomes unreachable. This occurs often due to
82 gimplification of conditionals.
87 This transformation, implemented in value_replacement, replaces
90 if (a != b) goto bb2; else goto bb1;
93 x = PHI <a (bb1), b (bb0), ...>;
99 x = PHI <b (bb0), ...>;
101 This opportunity can sometimes occur as a result of other
107 This transformation, implemented in abs_replacement, replaces
110 if (a >= 0) goto bb2; else goto bb1;
114 x = PHI <x (bb1), a (bb0), ...>;
121 x = PHI <x' (bb0), ...>;
126 This transformation, minmax_replacement replaces
129 if (a <= b) goto bb2; else goto bb1;
132 x = PHI <b (bb1), a (bb0), ...>;
139 x = PHI <x' (bb0), ...>;
141 A similar transformation is done for MAX_EXPR. */
144 tree_ssa_phiopt (void)
146 return tree_ssa_phiopt_worker (false);
149 /* This pass tries to transform conditional stores into unconditional
150 ones, enabling further simplifications with the simpler then and else
151 blocks. In particular it replaces this:
154 if (cond) goto bb2; else goto bb1;
162 if (cond) goto bb1; else goto bb2;
166 condtmp = PHI <RHS, condtmp'>
169 This transformation can only be done under several constraints,
170 documented below. It also replaces:
173 if (cond) goto bb2; else goto bb1;
184 if (cond) goto bb3; else goto bb1;
187 condtmp = PHI <RHS1, RHS2>
191 tree_ssa_cs_elim (void)
193 return tree_ssa_phiopt_worker (true);
196 /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
199 single_non_singleton_phi_for_edges (gimple_seq seq
, edge e0
, edge e1
)
201 gimple_stmt_iterator i
;
203 if (gimple_seq_singleton_p (seq
))
204 return gsi_stmt (gsi_start (seq
));
205 for (i
= gsi_start (seq
); !gsi_end_p (i
); gsi_next (&i
))
207 gimple p
= gsi_stmt (i
);
208 /* If the PHI arguments are equal then we can skip this PHI. */
209 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p
, e0
->dest_idx
),
210 gimple_phi_arg_def (p
, e1
->dest_idx
)))
213 /* If we already have a PHI that has the two edge arguments are
214 different, then return it is not a singleton for these PHIs. */
223 /* For conditional store replacement we need a temporary to
224 put the old contents of the memory in. */
225 static tree condstoretemp
;
227 /* The core routine of conditional store replacement and normal
228 phi optimizations. Both share much of the infrastructure in how
229 to match applicable basic block patterns. DO_STORE_ELIM is true
230 when we want to do conditional store replacement, false otherwise. */
232 tree_ssa_phiopt_worker (bool do_store_elim
)
235 basic_block
*bb_order
;
237 bool cfgchanged
= false;
238 struct pointer_set_t
*nontrap
= 0;
242 condstoretemp
= NULL_TREE
;
243 /* Calculate the set of non-trapping memory accesses. */
244 nontrap
= get_non_trapping ();
247 /* Search every basic block for COND_EXPR we may be able to optimize.
249 We walk the blocks in order that guarantees that a block with
250 a single predecessor is processed before the predecessor.
251 This ensures that we collapse inner ifs before visiting the
252 outer ones, and also that we do not try to visit a removed
254 bb_order
= blocks_in_phiopt_order ();
255 n
= n_basic_blocks
- NUM_FIXED_BLOCKS
;
257 for (i
= 0; i
< n
; i
++)
259 gimple cond_stmt
, phi
;
260 basic_block bb1
, bb2
;
266 cond_stmt
= last_stmt (bb
);
267 /* Check to see if the last statement is a GIMPLE_COND. */
269 || gimple_code (cond_stmt
) != GIMPLE_COND
)
272 e1
= EDGE_SUCC (bb
, 0);
274 e2
= EDGE_SUCC (bb
, 1);
277 /* We cannot do the optimization on abnormal edges. */
278 if ((e1
->flags
& EDGE_ABNORMAL
) != 0
279 || (e2
->flags
& EDGE_ABNORMAL
) != 0)
282 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
283 if (EDGE_COUNT (bb1
->succs
) == 0
285 || EDGE_COUNT (bb2
->succs
) == 0)
288 /* Find the bb which is the fall through to the other. */
289 if (EDGE_SUCC (bb1
, 0)->dest
== bb2
)
291 else if (EDGE_SUCC (bb2
, 0)->dest
== bb1
)
293 basic_block bb_tmp
= bb1
;
300 else if (do_store_elim
301 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
303 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
305 if (!single_succ_p (bb1
)
306 || (EDGE_SUCC (bb1
, 0)->flags
& EDGE_FALLTHRU
) == 0
307 || !single_succ_p (bb2
)
308 || (EDGE_SUCC (bb2
, 0)->flags
& EDGE_FALLTHRU
) == 0
309 || EDGE_COUNT (bb3
->preds
) != 2)
311 if (cond_if_else_store_replacement (bb1
, bb2
, bb3
))
318 e1
= EDGE_SUCC (bb1
, 0);
320 /* Make sure that bb1 is just a fall through. */
321 if (!single_succ_p (bb1
)
322 || (e1
->flags
& EDGE_FALLTHRU
) == 0)
325 /* Also make sure that bb1 only have one predecessor and that it
327 if (!single_pred_p (bb1
)
328 || single_pred (bb1
) != bb
)
333 /* bb1 is the middle block, bb2 the join block, bb the split block,
334 e1 the fallthrough edge from bb1 to bb2. We can't do the
335 optimization if the join block has more than two predecessors. */
336 if (EDGE_COUNT (bb2
->preds
) > 2)
338 if (cond_store_replacement (bb1
, bb2
, e1
, e2
, nontrap
))
343 gimple_seq phis
= phi_nodes (bb2
);
344 gimple_stmt_iterator gsi
;
345 bool candorest
= true;
347 /* Value replacement can work with more than one PHI
348 so try that first. */
349 for (gsi
= gsi_start (phis
); !gsi_end_p (gsi
); gsi_next (&gsi
))
351 phi
= gsi_stmt (gsi
);
352 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
353 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
354 if (value_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
) == 2)
365 phi
= single_non_singleton_phi_for_edges (phis
, e1
, e2
);
369 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
370 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
372 /* Something is wrong if we cannot find the arguments in the PHI
374 gcc_assert (arg0
!= NULL
&& arg1
!= NULL
);
376 /* Do the replacement of conditional if it can be done. */
377 if (conditional_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
379 else if (abs_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
381 else if (minmax_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
389 pointer_set_destroy (nontrap
);
390 /* If the CFG has changed, we should cleanup the CFG. */
391 if (cfgchanged
&& do_store_elim
)
393 /* In cond-store replacement we have added some loads on edges
394 and new VOPS (as we moved the store, and created a load). */
395 gsi_commit_edge_inserts ();
396 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
399 return TODO_cleanup_cfg
;
403 /* Returns the list of basic blocks in the function in an order that guarantees
404 that if a block X has just a single predecessor Y, then Y is after X in the
408 blocks_in_phiopt_order (void)
411 basic_block
*order
= XNEWVEC (basic_block
, n_basic_blocks
);
412 unsigned n
= n_basic_blocks
- NUM_FIXED_BLOCKS
;
414 sbitmap visited
= sbitmap_alloc (last_basic_block
);
416 #define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index))
417 #define VISITED_P(BB) (TEST_BIT (visited, (BB)->index))
419 sbitmap_zero (visited
);
421 MARK_VISITED (ENTRY_BLOCK_PTR
);
427 /* Walk the predecessors of x as long as they have precisely one
428 predecessor and add them to the list, so that they get stored
431 single_pred_p (y
) && !VISITED_P (single_pred (y
));
434 for (y
= x
, i
= n
- np
;
435 single_pred_p (y
) && !VISITED_P (single_pred (y
));
436 y
= single_pred (y
), i
++)
444 gcc_assert (i
== n
- 1);
448 sbitmap_free (visited
);
457 /* Return TRUE if block BB has no executable statements, otherwise return
461 empty_block_p (basic_block bb
)
463 /* BB must have no executable statements. */
464 gimple_stmt_iterator gsi
= gsi_after_labels (bb
);
469 if (is_gimple_debug (gsi_stmt (gsi
)))
470 gsi_next_nondebug (&gsi
);
471 return gsi_end_p (gsi
);
474 /* Replace PHI node element whose edge is E in block BB with variable NEW.
475 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
476 is known to have two edges, one of which must reach BB). */
479 replace_phi_edge_with_variable (basic_block cond_block
,
480 edge e
, gimple phi
, tree new_tree
)
482 basic_block bb
= gimple_bb (phi
);
483 basic_block block_to_remove
;
484 gimple_stmt_iterator gsi
;
486 /* Change the PHI argument to new. */
487 SET_USE (PHI_ARG_DEF_PTR (phi
, e
->dest_idx
), new_tree
);
489 /* Remove the empty basic block. */
490 if (EDGE_SUCC (cond_block
, 0)->dest
== bb
)
492 EDGE_SUCC (cond_block
, 0)->flags
|= EDGE_FALLTHRU
;
493 EDGE_SUCC (cond_block
, 0)->flags
&= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
494 EDGE_SUCC (cond_block
, 0)->probability
= REG_BR_PROB_BASE
;
495 EDGE_SUCC (cond_block
, 0)->count
+= EDGE_SUCC (cond_block
, 1)->count
;
497 block_to_remove
= EDGE_SUCC (cond_block
, 1)->dest
;
501 EDGE_SUCC (cond_block
, 1)->flags
|= EDGE_FALLTHRU
;
502 EDGE_SUCC (cond_block
, 1)->flags
503 &= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
504 EDGE_SUCC (cond_block
, 1)->probability
= REG_BR_PROB_BASE
;
505 EDGE_SUCC (cond_block
, 1)->count
+= EDGE_SUCC (cond_block
, 0)->count
;
507 block_to_remove
= EDGE_SUCC (cond_block
, 0)->dest
;
509 delete_basic_block (block_to_remove
);
511 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
512 gsi
= gsi_last_bb (cond_block
);
513 gsi_remove (&gsi
, true);
515 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
517 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
522 /* The function conditional_replacement does the main work of doing the
523 conditional replacement. Return true if the replacement is done.
524 Otherwise return false.
525 BB is the basic block where the replacement is going to be done on. ARG0
526 is argument 0 from PHI. Likewise for ARG1. */
529 conditional_replacement (basic_block cond_bb
, basic_block middle_bb
,
530 edge e0
, edge e1
, gimple phi
,
531 tree arg0
, tree arg1
)
534 gimple stmt
, new_stmt
;
536 gimple_stmt_iterator gsi
;
537 edge true_edge
, false_edge
;
538 tree new_var
, new_var2
;
540 /* FIXME: Gimplification of complex type is too hard for now. */
541 if (TREE_CODE (TREE_TYPE (arg0
)) == COMPLEX_TYPE
542 || TREE_CODE (TREE_TYPE (arg1
)) == COMPLEX_TYPE
)
545 /* The PHI arguments have the constants 0 and 1, then convert
546 it to the conditional. */
547 if ((integer_zerop (arg0
) && integer_onep (arg1
))
548 || (integer_zerop (arg1
) && integer_onep (arg0
)))
553 if (!empty_block_p (middle_bb
))
556 /* At this point we know we have a GIMPLE_COND with two successors.
557 One successor is BB, the other successor is an empty block which
558 falls through into BB.
560 There is a single PHI node at the join point (BB) and its arguments
561 are constants (0, 1).
563 So, given the condition COND, and the two PHI arguments, we can
564 rewrite this PHI into non-branching code:
566 dest = (COND) or dest = COND'
568 We use the condition as-is if the argument associated with the
569 true edge has the value one or the argument associated with the
570 false edge as the value zero. Note that those conditions are not
571 the same since only one of the outgoing edges from the GIMPLE_COND
572 will directly reach BB and thus be associated with an argument. */
574 stmt
= last_stmt (cond_bb
);
575 result
= PHI_RESULT (phi
);
577 /* To handle special cases like floating point comparison, it is easier and
578 less error-prone to build a tree and gimplify it on the fly though it is
580 cond
= fold_build2_loc (gimple_location (stmt
),
581 gimple_cond_code (stmt
), boolean_type_node
,
582 gimple_cond_lhs (stmt
), gimple_cond_rhs (stmt
));
584 /* We need to know which is the true edge and which is the false
585 edge so that we know when to invert the condition below. */
586 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
587 if ((e0
== true_edge
&& integer_zerop (arg0
))
588 || (e0
== false_edge
&& integer_onep (arg0
))
589 || (e1
== true_edge
&& integer_zerop (arg1
))
590 || (e1
== false_edge
&& integer_onep (arg1
)))
591 cond
= fold_build1_loc (gimple_location (stmt
),
592 TRUTH_NOT_EXPR
, TREE_TYPE (cond
), cond
);
594 /* Insert our new statements at the end of conditional block before the
596 gsi
= gsi_for_stmt (stmt
);
597 new_var
= force_gimple_operand_gsi (&gsi
, cond
, true, NULL
, true,
600 if (!useless_type_conversion_p (TREE_TYPE (result
), TREE_TYPE (new_var
)))
602 source_location locus_0
, locus_1
;
604 new_var2
= create_tmp_var (TREE_TYPE (result
), NULL
);
605 add_referenced_var (new_var2
);
606 new_stmt
= gimple_build_assign_with_ops (CONVERT_EXPR
, new_var2
,
608 new_var2
= make_ssa_name (new_var2
, new_stmt
);
609 gimple_assign_set_lhs (new_stmt
, new_var2
);
610 gsi_insert_before (&gsi
, new_stmt
, GSI_SAME_STMT
);
613 /* Set the locus to the first argument, unless is doesn't have one. */
614 locus_0
= gimple_phi_arg_location (phi
, 0);
615 locus_1
= gimple_phi_arg_location (phi
, 1);
616 if (locus_0
== UNKNOWN_LOCATION
)
618 gimple_set_location (new_stmt
, locus_0
);
621 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_var
);
623 /* Note that we optimized this PHI. */
627 /* Update *ARG which is defined in STMT so that it contains the
628 computed value if that seems profitable. Return true if the
629 statement is made dead by that rewriting. */
632 jump_function_from_stmt (tree
*arg
, gimple stmt
)
634 enum tree_code code
= gimple_assign_rhs_code (stmt
);
635 if (code
== ADDR_EXPR
)
637 /* For arg = &p->i transform it to p, if possible. */
638 tree rhs1
= gimple_assign_rhs1 (stmt
);
639 HOST_WIDE_INT offset
;
640 tree tem
= get_addr_base_and_unit_offset (TREE_OPERAND (rhs1
, 0),
643 && TREE_CODE (tem
) == MEM_REF
645 (double_int_add (mem_ref_offset (tem
),
646 shwi_to_double_int (offset
))))
648 *arg
= TREE_OPERAND (tem
, 0);
652 /* TODO: Much like IPA-CP jump-functions we want to handle constant
653 additions symbolically here, and we'd need to update the comparison
654 code that compares the arg + cst tuples in our caller. For now the
655 code above exactly handles the VEC_BASE pattern from vec.h. */
659 /* The function value_replacement does the main work of doing the value
660 replacement. Return non-zero if the replacement is done. Otherwise return
661 0. If we remove the middle basic block, return 2.
662 BB is the basic block where the replacement is going to be done on. ARG0
663 is argument 0 from the PHI. Likewise for ARG1. */
666 value_replacement (basic_block cond_bb
, basic_block middle_bb
,
667 edge e0
, edge e1
, gimple phi
,
668 tree arg0
, tree arg1
)
670 gimple_stmt_iterator gsi
;
672 edge true_edge
, false_edge
;
674 bool emtpy_or_with_defined_p
= true;
676 /* If the type says honor signed zeros we cannot do this
678 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
681 /* If there is a statement in MIDDLE_BB that defines one of the PHI
682 arguments, then adjust arg0 or arg1. */
683 gsi
= gsi_after_labels (middle_bb
);
684 if (!gsi_end_p (gsi
) && is_gimple_debug (gsi_stmt (gsi
)))
685 gsi_next_nondebug (&gsi
);
686 while (!gsi_end_p (gsi
))
688 gimple stmt
= gsi_stmt (gsi
);
690 gsi_next_nondebug (&gsi
);
691 if (!is_gimple_assign (stmt
))
693 emtpy_or_with_defined_p
= false;
696 /* Now try to adjust arg0 or arg1 according to the computation
698 lhs
= gimple_assign_lhs (stmt
);
700 && jump_function_from_stmt (&arg0
, stmt
))
702 && jump_function_from_stmt (&arg1
, stmt
)))
703 emtpy_or_with_defined_p
= false;
706 cond
= last_stmt (cond_bb
);
707 code
= gimple_cond_code (cond
);
709 /* This transformation is only valid for equality comparisons. */
710 if (code
!= NE_EXPR
&& code
!= EQ_EXPR
)
713 /* We need to know which is the true edge and which is the false
714 edge so that we know if have abs or negative abs. */
715 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
717 /* At this point we know we have a COND_EXPR with two successors.
718 One successor is BB, the other successor is an empty block which
719 falls through into BB.
721 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
723 There is a single PHI node at the join point (BB) with two arguments.
725 We now need to verify that the two arguments in the PHI node match
726 the two arguments to the equality comparison. */
728 if ((operand_equal_for_phi_arg_p (arg0
, gimple_cond_lhs (cond
))
729 && operand_equal_for_phi_arg_p (arg1
, gimple_cond_rhs (cond
)))
730 || (operand_equal_for_phi_arg_p (arg1
, gimple_cond_lhs (cond
))
731 && operand_equal_for_phi_arg_p (arg0
, gimple_cond_rhs (cond
))))
736 /* For NE_EXPR, we want to build an assignment result = arg where
737 arg is the PHI argument associated with the true edge. For
738 EQ_EXPR we want the PHI argument associated with the false edge. */
739 e
= (code
== NE_EXPR
? true_edge
: false_edge
);
741 /* Unfortunately, E may not reach BB (it may instead have gone to
742 OTHER_BLOCK). If that is the case, then we want the single outgoing
743 edge from OTHER_BLOCK which reaches BB and represents the desired
744 path from COND_BLOCK. */
745 if (e
->dest
== middle_bb
)
746 e
= single_succ_edge (e
->dest
);
748 /* Now we know the incoming edge to BB that has the argument for the
749 RHS of our new assignment statement. */
755 /* If the middle basic block was empty or is defining the
756 PHI arguments and this is a single phi where the args are different
757 for the edges e0 and e1 then we can remove the middle basic block. */
758 if (emtpy_or_with_defined_p
759 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)),
762 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, arg
);
763 /* Note that we optimized this PHI. */
768 /* Replace the PHI arguments with arg. */
769 SET_PHI_ARG_DEF (phi
, e0
->dest_idx
, arg
);
770 SET_PHI_ARG_DEF (phi
, e1
->dest_idx
, arg
);
771 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
773 fprintf (dump_file
, "PHI ");
774 print_generic_expr (dump_file
, gimple_phi_result (phi
), 0);
775 fprintf (dump_file
, " reduced for COND_EXPR in block %d to ",
777 print_generic_expr (dump_file
, arg
, 0);
778 fprintf (dump_file
, ".\n");
787 /* The function minmax_replacement does the main work of doing the minmax
788 replacement. Return true if the replacement is done. Otherwise return
790 BB is the basic block where the replacement is going to be done on. ARG0
791 is argument 0 from the PHI. Likewise for ARG1. */
794 minmax_replacement (basic_block cond_bb
, basic_block middle_bb
,
795 edge e0
, edge e1
, gimple phi
,
796 tree arg0
, tree arg1
)
799 gimple cond
, new_stmt
;
800 edge true_edge
, false_edge
;
801 enum tree_code cmp
, minmax
, ass_code
;
802 tree smaller
, larger
, arg_true
, arg_false
;
803 gimple_stmt_iterator gsi
, gsi_from
;
805 type
= TREE_TYPE (PHI_RESULT (phi
));
807 /* The optimization may be unsafe due to NaNs. */
808 if (HONOR_NANS (TYPE_MODE (type
)))
811 cond
= last_stmt (cond_bb
);
812 cmp
= gimple_cond_code (cond
);
814 /* This transformation is only valid for order comparisons. Record which
815 operand is smaller/larger if the result of the comparison is true. */
816 if (cmp
== LT_EXPR
|| cmp
== LE_EXPR
)
818 smaller
= gimple_cond_lhs (cond
);
819 larger
= gimple_cond_rhs (cond
);
821 else if (cmp
== GT_EXPR
|| cmp
== GE_EXPR
)
823 smaller
= gimple_cond_rhs (cond
);
824 larger
= gimple_cond_lhs (cond
);
829 /* We need to know which is the true edge and which is the false
830 edge so that we know if have abs or negative abs. */
831 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
833 /* Forward the edges over the middle basic block. */
834 if (true_edge
->dest
== middle_bb
)
835 true_edge
= EDGE_SUCC (true_edge
->dest
, 0);
836 if (false_edge
->dest
== middle_bb
)
837 false_edge
= EDGE_SUCC (false_edge
->dest
, 0);
841 gcc_assert (false_edge
== e1
);
847 gcc_assert (false_edge
== e0
);
848 gcc_assert (true_edge
== e1
);
853 if (empty_block_p (middle_bb
))
855 if (operand_equal_for_phi_arg_p (arg_true
, smaller
)
856 && operand_equal_for_phi_arg_p (arg_false
, larger
))
860 if (smaller < larger)
866 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
)
867 && operand_equal_for_phi_arg_p (arg_true
, larger
))
874 /* Recognize the following case, assuming d <= u:
880 This is equivalent to
885 gimple assign
= last_and_only_stmt (middle_bb
);
886 tree lhs
, op0
, op1
, bound
;
889 || gimple_code (assign
) != GIMPLE_ASSIGN
)
892 lhs
= gimple_assign_lhs (assign
);
893 ass_code
= gimple_assign_rhs_code (assign
);
894 if (ass_code
!= MAX_EXPR
&& ass_code
!= MIN_EXPR
)
896 op0
= gimple_assign_rhs1 (assign
);
897 op1
= gimple_assign_rhs2 (assign
);
899 if (true_edge
->src
== middle_bb
)
901 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
902 if (!operand_equal_for_phi_arg_p (lhs
, arg_true
))
905 if (operand_equal_for_phi_arg_p (arg_false
, larger
))
909 if (smaller < larger)
911 r' = MAX_EXPR (smaller, bound)
913 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
914 if (ass_code
!= MAX_EXPR
)
918 if (operand_equal_for_phi_arg_p (op0
, smaller
))
920 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
925 /* We need BOUND <= LARGER. */
926 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
930 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
))
934 if (smaller < larger)
936 r' = MIN_EXPR (larger, bound)
938 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
939 if (ass_code
!= MIN_EXPR
)
943 if (operand_equal_for_phi_arg_p (op0
, larger
))
945 else if (operand_equal_for_phi_arg_p (op1
, larger
))
950 /* We need BOUND >= SMALLER. */
951 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
960 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
961 if (!operand_equal_for_phi_arg_p (lhs
, arg_false
))
964 if (operand_equal_for_phi_arg_p (arg_true
, larger
))
968 if (smaller > larger)
970 r' = MIN_EXPR (smaller, bound)
972 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
973 if (ass_code
!= MIN_EXPR
)
977 if (operand_equal_for_phi_arg_p (op0
, smaller
))
979 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
984 /* We need BOUND >= LARGER. */
985 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
989 else if (operand_equal_for_phi_arg_p (arg_true
, smaller
))
993 if (smaller > larger)
995 r' = MAX_EXPR (larger, bound)
997 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
998 if (ass_code
!= MAX_EXPR
)
1002 if (operand_equal_for_phi_arg_p (op0
, larger
))
1004 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1009 /* We need BOUND <= SMALLER. */
1010 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1018 /* Move the statement from the middle block. */
1019 gsi
= gsi_last_bb (cond_bb
);
1020 gsi_from
= gsi_last_nondebug_bb (middle_bb
);
1021 gsi_move_before (&gsi_from
, &gsi
);
1024 /* Emit the statement to compute min/max. */
1025 result
= duplicate_ssa_name (PHI_RESULT (phi
), NULL
);
1026 new_stmt
= gimple_build_assign_with_ops (minmax
, result
, arg0
, arg1
);
1027 gsi
= gsi_last_bb (cond_bb
);
1028 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1030 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1034 /* The function absolute_replacement does the main work of doing the absolute
1035 replacement. Return true if the replacement is done. Otherwise return
1037 bb is the basic block where the replacement is going to be done on. arg0
1038 is argument 0 from the phi. Likewise for arg1. */
1041 abs_replacement (basic_block cond_bb
, basic_block middle_bb
,
1042 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1043 gimple phi
, tree arg0
, tree arg1
)
1046 gimple new_stmt
, cond
;
1047 gimple_stmt_iterator gsi
;
1048 edge true_edge
, false_edge
;
1053 enum tree_code cond_code
;
1055 /* If the type says honor signed zeros we cannot do this
1057 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
1060 /* OTHER_BLOCK must have only one executable statement which must have the
1061 form arg0 = -arg1 or arg1 = -arg0. */
1063 assign
= last_and_only_stmt (middle_bb
);
1064 /* If we did not find the proper negation assignment, then we can not
1069 /* If we got here, then we have found the only executable statement
1070 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1071 arg1 = -arg0, then we can not optimize. */
1072 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1075 lhs
= gimple_assign_lhs (assign
);
1077 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1080 rhs
= gimple_assign_rhs1 (assign
);
1082 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1083 if (!(lhs
== arg0
&& rhs
== arg1
)
1084 && !(lhs
== arg1
&& rhs
== arg0
))
1087 cond
= last_stmt (cond_bb
);
1088 result
= PHI_RESULT (phi
);
1090 /* Only relationals comparing arg[01] against zero are interesting. */
1091 cond_code
= gimple_cond_code (cond
);
1092 if (cond_code
!= GT_EXPR
&& cond_code
!= GE_EXPR
1093 && cond_code
!= LT_EXPR
&& cond_code
!= LE_EXPR
)
1096 /* Make sure the conditional is arg[01] OP y. */
1097 if (gimple_cond_lhs (cond
) != rhs
)
1100 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond
)))
1101 ? real_zerop (gimple_cond_rhs (cond
))
1102 : integer_zerop (gimple_cond_rhs (cond
)))
1107 /* We need to know which is the true edge and which is the false
1108 edge so that we know if have abs or negative abs. */
1109 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1111 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1112 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1113 the false edge goes to OTHER_BLOCK. */
1114 if (cond_code
== GT_EXPR
|| cond_code
== GE_EXPR
)
1119 if (e
->dest
== middle_bb
)
1124 result
= duplicate_ssa_name (result
, NULL
);
1128 tree tmp
= create_tmp_var (TREE_TYPE (result
), NULL
);
1129 add_referenced_var (tmp
);
1130 lhs
= make_ssa_name (tmp
, NULL
);
1135 /* Build the modify expression with abs expression. */
1136 new_stmt
= gimple_build_assign_with_ops (ABS_EXPR
, lhs
, rhs
, NULL
);
1138 gsi
= gsi_last_bb (cond_bb
);
1139 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1143 /* Get the right GSI. We want to insert after the recently
1144 added ABS_EXPR statement (which we know is the first statement
1146 new_stmt
= gimple_build_assign_with_ops (NEGATE_EXPR
, result
, lhs
, NULL
);
1148 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1151 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1153 /* Note that we optimized this PHI. */
1157 /* Auxiliary functions to determine the set of memory accesses which
1158 can't trap because they are preceded by accesses to the same memory
1159 portion. We do that for MEM_REFs, so we only need to track
1160 the SSA_NAME of the pointer indirectly referenced. The algorithm
1161 simply is a walk over all instructions in dominator order. When
1162 we see an MEM_REF we determine if we've already seen a same
1163 ref anywhere up to the root of the dominator tree. If we do the
1164 current access can't trap. If we don't see any dominating access
1165 the current access might trap, but might also make later accesses
1166 non-trapping, so we remember it. We need to be careful with loads
1167 or stores, for instance a load might not trap, while a store would,
1168 so if we see a dominating read access this doesn't mean that a later
1169 write access would not trap. Hence we also need to differentiate the
1170 type of access(es) seen.
1172 ??? We currently are very conservative and assume that a load might
1173 trap even if a store doesn't (write-only memory). This probably is
1174 overly conservative. */
1176 /* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1177 through it was seen, which would constitute a no-trap region for
1181 unsigned int ssa_name_ver
;
1183 HOST_WIDE_INT offset
, size
;
1187 /* The hash table for remembering what we've seen. */
1188 static htab_t seen_ssa_names
;
1190 /* The set of MEM_REFs which can't trap. */
1191 static struct pointer_set_t
*nontrap_set
;
1193 /* The hash function. */
1195 name_to_bb_hash (const void *p
)
1197 const struct name_to_bb
*n
= (const struct name_to_bb
*) p
;
1198 return n
->ssa_name_ver
^ (((hashval_t
) n
->store
) << 31)
1199 ^ (n
->offset
<< 6) ^ (n
->size
<< 3);
1202 /* The equality function of *P1 and *P2. */
1204 name_to_bb_eq (const void *p1
, const void *p2
)
1206 const struct name_to_bb
*n1
= (const struct name_to_bb
*)p1
;
1207 const struct name_to_bb
*n2
= (const struct name_to_bb
*)p2
;
1209 return n1
->ssa_name_ver
== n2
->ssa_name_ver
1210 && n1
->store
== n2
->store
1211 && n1
->offset
== n2
->offset
1212 && n1
->size
== n2
->size
;
1215 /* We see the expression EXP in basic block BB. If it's an interesting
1216 expression (an MEM_REF through an SSA_NAME) possibly insert the
1217 expression into the set NONTRAP or the hash table of seen expressions.
1218 STORE is true if this expression is on the LHS, otherwise it's on
1221 add_or_mark_expr (basic_block bb
, tree exp
,
1222 struct pointer_set_t
*nontrap
, bool store
)
1226 if (TREE_CODE (exp
) == MEM_REF
1227 && TREE_CODE (TREE_OPERAND (exp
, 0)) == SSA_NAME
1228 && host_integerp (TREE_OPERAND (exp
, 1), 0)
1229 && (size
= int_size_in_bytes (TREE_TYPE (exp
))) > 0)
1231 tree name
= TREE_OPERAND (exp
, 0);
1232 struct name_to_bb map
;
1234 struct name_to_bb
*n2bb
;
1235 basic_block found_bb
= 0;
1237 /* Try to find the last seen MEM_REF through the same
1238 SSA_NAME, which can trap. */
1239 map
.ssa_name_ver
= SSA_NAME_VERSION (name
);
1242 map
.offset
= tree_low_cst (TREE_OPERAND (exp
, 1), 0);
1245 slot
= htab_find_slot (seen_ssa_names
, &map
, INSERT
);
1246 n2bb
= (struct name_to_bb
*) *slot
;
1248 found_bb
= n2bb
->bb
;
1250 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1251 (it's in a basic block on the path from us to the dominator root)
1252 then we can't trap. */
1253 if (found_bb
&& found_bb
->aux
== (void *)1)
1255 pointer_set_insert (nontrap
, exp
);
1259 /* EXP might trap, so insert it into the hash table. */
1266 n2bb
= XNEW (struct name_to_bb
);
1267 n2bb
->ssa_name_ver
= SSA_NAME_VERSION (name
);
1269 n2bb
->store
= store
;
1270 n2bb
->offset
= map
.offset
;
1278 /* Called by walk_dominator_tree, when entering the block BB. */
1280 nt_init_block (struct dom_walk_data
*data ATTRIBUTE_UNUSED
, basic_block bb
)
1282 gimple_stmt_iterator gsi
;
1283 /* Mark this BB as being on the path to dominator root. */
1286 /* And walk the statements in order. */
1287 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1289 gimple stmt
= gsi_stmt (gsi
);
1291 if (gimple_assign_single_p (stmt
))
1293 add_or_mark_expr (bb
, gimple_assign_lhs (stmt
), nontrap_set
, true);
1294 add_or_mark_expr (bb
, gimple_assign_rhs1 (stmt
), nontrap_set
, false);
1299 /* Called by walk_dominator_tree, when basic block BB is exited. */
1301 nt_fini_block (struct dom_walk_data
*data ATTRIBUTE_UNUSED
, basic_block bb
)
1303 /* This BB isn't on the path to dominator root anymore. */
1307 /* This is the entry point of gathering non trapping memory accesses.
1308 It will do a dominator walk over the whole function, and it will
1309 make use of the bb->aux pointers. It returns a set of trees
1310 (the MEM_REFs itself) which can't trap. */
1311 static struct pointer_set_t
*
1312 get_non_trapping (void)
1314 struct pointer_set_t
*nontrap
;
1315 struct dom_walk_data walk_data
;
1317 nontrap
= pointer_set_create ();
1318 seen_ssa_names
= htab_create (128, name_to_bb_hash
, name_to_bb_eq
,
1320 /* We're going to do a dominator walk, so ensure that we have
1321 dominance information. */
1322 calculate_dominance_info (CDI_DOMINATORS
);
1324 /* Setup callbacks for the generic dominator tree walker. */
1325 nontrap_set
= nontrap
;
1326 walk_data
.dom_direction
= CDI_DOMINATORS
;
1327 walk_data
.initialize_block_local_data
= NULL
;
1328 walk_data
.before_dom_children
= nt_init_block
;
1329 walk_data
.after_dom_children
= nt_fini_block
;
1330 walk_data
.global_data
= NULL
;
1331 walk_data
.block_local_data_size
= 0;
1333 init_walk_dominator_tree (&walk_data
);
1334 walk_dominator_tree (&walk_data
, ENTRY_BLOCK_PTR
);
1335 fini_walk_dominator_tree (&walk_data
);
1336 htab_delete (seen_ssa_names
);
1341 /* Do the main work of conditional store replacement. We already know
1342 that the recognized pattern looks like so:
1345 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1348 fallthrough (edge E0)
1352 We check that MIDDLE_BB contains only one store, that that store
1353 doesn't trap (not via NOTRAP, but via checking if an access to the same
1354 memory location dominates us) and that the store has a "simple" RHS. */
1357 cond_store_replacement (basic_block middle_bb
, basic_block join_bb
,
1358 edge e0
, edge e1
, struct pointer_set_t
*nontrap
)
1360 gimple assign
= last_and_only_stmt (middle_bb
);
1361 tree lhs
, rhs
, name
;
1362 gimple newphi
, new_stmt
;
1363 gimple_stmt_iterator gsi
;
1364 source_location locus
;
1366 /* Check if middle_bb contains of only one store. */
1368 || !gimple_assign_single_p (assign
))
1371 locus
= gimple_location (assign
);
1372 lhs
= gimple_assign_lhs (assign
);
1373 rhs
= gimple_assign_rhs1 (assign
);
1374 if (TREE_CODE (lhs
) != MEM_REF
1375 || TREE_CODE (TREE_OPERAND (lhs
, 0)) != SSA_NAME
1376 || !is_gimple_reg_type (TREE_TYPE (lhs
)))
1379 /* Prove that we can move the store down. We could also check
1380 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1381 whose value is not available readily, which we want to avoid. */
1382 if (!pointer_set_contains (nontrap
, lhs
))
1385 /* Now we've checked the constraints, so do the transformation:
1386 1) Remove the single store. */
1387 gsi
= gsi_for_stmt (assign
);
1388 unlink_stmt_vdef (assign
);
1389 gsi_remove (&gsi
, true);
1390 release_defs (assign
);
1392 /* 2) Create a temporary where we can store the old content
1393 of the memory touched by the store, if we need to. */
1394 if (!condstoretemp
|| TREE_TYPE (lhs
) != TREE_TYPE (condstoretemp
))
1395 condstoretemp
= create_tmp_reg (TREE_TYPE (lhs
), "cstore");
1396 add_referenced_var (condstoretemp
);
1398 /* 3) Insert a load from the memory of the store to the temporary
1399 on the edge which did not contain the store. */
1400 lhs
= unshare_expr (lhs
);
1401 new_stmt
= gimple_build_assign (condstoretemp
, lhs
);
1402 name
= make_ssa_name (condstoretemp
, new_stmt
);
1403 gimple_assign_set_lhs (new_stmt
, name
);
1404 gimple_set_location (new_stmt
, locus
);
1405 gsi_insert_on_edge (e1
, new_stmt
);
1407 /* 4) Create a PHI node at the join block, with one argument
1408 holding the old RHS, and the other holding the temporary
1409 where we stored the old memory contents. */
1410 newphi
= create_phi_node (condstoretemp
, join_bb
);
1411 add_phi_arg (newphi
, rhs
, e0
, locus
);
1412 add_phi_arg (newphi
, name
, e1
, locus
);
1414 lhs
= unshare_expr (lhs
);
1415 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1417 /* 5) Insert that PHI node. */
1418 gsi
= gsi_after_labels (join_bb
);
1419 if (gsi_end_p (gsi
))
1421 gsi
= gsi_last_bb (join_bb
);
1422 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1425 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1430 /* Do the main work of conditional store replacement. */
1433 cond_if_else_store_replacement_1 (basic_block then_bb
, basic_block else_bb
,
1434 basic_block join_bb
, gimple then_assign
,
1437 tree lhs_base
, lhs
, then_rhs
, else_rhs
;
1438 source_location then_locus
, else_locus
;
1439 gimple_stmt_iterator gsi
;
1440 gimple newphi
, new_stmt
;
1442 if (then_assign
== NULL
1443 || !gimple_assign_single_p (then_assign
)
1444 || gimple_clobber_p (then_assign
)
1445 || else_assign
== NULL
1446 || !gimple_assign_single_p (else_assign
)
1447 || gimple_clobber_p (else_assign
))
1450 lhs
= gimple_assign_lhs (then_assign
);
1451 if (!is_gimple_reg_type (TREE_TYPE (lhs
))
1452 || !operand_equal_p (lhs
, gimple_assign_lhs (else_assign
), 0))
1455 lhs_base
= get_base_address (lhs
);
1456 if (lhs_base
== NULL_TREE
1457 || (!DECL_P (lhs_base
) && TREE_CODE (lhs_base
) != MEM_REF
))
1460 then_rhs
= gimple_assign_rhs1 (then_assign
);
1461 else_rhs
= gimple_assign_rhs1 (else_assign
);
1462 then_locus
= gimple_location (then_assign
);
1463 else_locus
= gimple_location (else_assign
);
1465 /* Now we've checked the constraints, so do the transformation:
1466 1) Remove the stores. */
1467 gsi
= gsi_for_stmt (then_assign
);
1468 unlink_stmt_vdef (then_assign
);
1469 gsi_remove (&gsi
, true);
1470 release_defs (then_assign
);
1472 gsi
= gsi_for_stmt (else_assign
);
1473 unlink_stmt_vdef (else_assign
);
1474 gsi_remove (&gsi
, true);
1475 release_defs (else_assign
);
1477 /* 2) Create a temporary where we can store the old content
1478 of the memory touched by the store, if we need to. */
1479 if (!condstoretemp
|| TREE_TYPE (lhs
) != TREE_TYPE (condstoretemp
))
1480 condstoretemp
= create_tmp_reg (TREE_TYPE (lhs
), "cstore");
1481 add_referenced_var (condstoretemp
);
1483 /* 3) Create a PHI node at the join block, with one argument
1484 holding the old RHS, and the other holding the temporary
1485 where we stored the old memory contents. */
1486 newphi
= create_phi_node (condstoretemp
, join_bb
);
1487 add_phi_arg (newphi
, then_rhs
, EDGE_SUCC (then_bb
, 0), then_locus
);
1488 add_phi_arg (newphi
, else_rhs
, EDGE_SUCC (else_bb
, 0), else_locus
);
1490 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1492 /* 4) Insert that PHI node. */
1493 gsi
= gsi_after_labels (join_bb
);
1494 if (gsi_end_p (gsi
))
1496 gsi
= gsi_last_bb (join_bb
);
1497 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1500 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1505 /* Conditional store replacement. We already know
1506 that the recognized pattern looks like so:
1509 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
1519 fallthrough (edge E0)
1523 We check that it is safe to sink the store to JOIN_BB by verifying that
1524 there are no read-after-write or write-after-write dependencies in
1525 THEN_BB and ELSE_BB. */
1528 cond_if_else_store_replacement (basic_block then_bb
, basic_block else_bb
,
1529 basic_block join_bb
)
1531 gimple then_assign
= last_and_only_stmt (then_bb
);
1532 gimple else_assign
= last_and_only_stmt (else_bb
);
1533 VEC (data_reference_p
, heap
) *then_datarefs
, *else_datarefs
;
1534 VEC (ddr_p
, heap
) *then_ddrs
, *else_ddrs
;
1535 gimple then_store
, else_store
;
1536 bool found
, ok
= false, res
;
1537 struct data_dependence_relation
*ddr
;
1538 data_reference_p then_dr
, else_dr
;
1540 tree then_lhs
, else_lhs
;
1541 VEC (gimple
, heap
) *then_stores
, *else_stores
;
1542 basic_block blocks
[3];
1544 if (MAX_STORES_TO_SINK
== 0)
1547 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
1548 if (then_assign
&& else_assign
)
1549 return cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1550 then_assign
, else_assign
);
1552 /* Find data references. */
1553 then_datarefs
= VEC_alloc (data_reference_p
, heap
, 1);
1554 else_datarefs
= VEC_alloc (data_reference_p
, heap
, 1);
1555 if ((find_data_references_in_bb (NULL
, then_bb
, &then_datarefs
)
1557 || !VEC_length (data_reference_p
, then_datarefs
)
1558 || (find_data_references_in_bb (NULL
, else_bb
, &else_datarefs
)
1560 || !VEC_length (data_reference_p
, else_datarefs
))
1562 free_data_refs (then_datarefs
);
1563 free_data_refs (else_datarefs
);
1567 /* Find pairs of stores with equal LHS. */
1568 then_stores
= VEC_alloc (gimple
, heap
, 1);
1569 else_stores
= VEC_alloc (gimple
, heap
, 1);
1570 FOR_EACH_VEC_ELT (data_reference_p
, then_datarefs
, i
, then_dr
)
1572 if (DR_IS_READ (then_dr
))
1575 then_store
= DR_STMT (then_dr
);
1576 then_lhs
= gimple_get_lhs (then_store
);
1579 FOR_EACH_VEC_ELT (data_reference_p
, else_datarefs
, j
, else_dr
)
1581 if (DR_IS_READ (else_dr
))
1584 else_store
= DR_STMT (else_dr
);
1585 else_lhs
= gimple_get_lhs (else_store
);
1587 if (operand_equal_p (then_lhs
, else_lhs
, 0))
1597 VEC_safe_push (gimple
, heap
, then_stores
, then_store
);
1598 VEC_safe_push (gimple
, heap
, else_stores
, else_store
);
1601 /* No pairs of stores found. */
1602 if (!VEC_length (gimple
, then_stores
)
1603 || VEC_length (gimple
, then_stores
) > (unsigned) MAX_STORES_TO_SINK
)
1605 free_data_refs (then_datarefs
);
1606 free_data_refs (else_datarefs
);
1607 VEC_free (gimple
, heap
, then_stores
);
1608 VEC_free (gimple
, heap
, else_stores
);
1612 /* Compute and check data dependencies in both basic blocks. */
1613 then_ddrs
= VEC_alloc (ddr_p
, heap
, 1);
1614 else_ddrs
= VEC_alloc (ddr_p
, heap
, 1);
1615 compute_all_dependences (then_datarefs
, &then_ddrs
, NULL
, false);
1616 compute_all_dependences (else_datarefs
, &else_ddrs
, NULL
, false);
1617 blocks
[0] = then_bb
;
1618 blocks
[1] = else_bb
;
1619 blocks
[2] = join_bb
;
1620 renumber_gimple_stmt_uids_in_blocks (blocks
, 3);
1622 /* Check that there are no read-after-write or write-after-write dependencies
1624 FOR_EACH_VEC_ELT (ddr_p
, then_ddrs
, i
, ddr
)
1626 struct data_reference
*dra
= DDR_A (ddr
);
1627 struct data_reference
*drb
= DDR_B (ddr
);
1629 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1630 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1631 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1632 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1633 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1634 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1636 free_dependence_relations (then_ddrs
);
1637 free_dependence_relations (else_ddrs
);
1638 free_data_refs (then_datarefs
);
1639 free_data_refs (else_datarefs
);
1640 VEC_free (gimple
, heap
, then_stores
);
1641 VEC_free (gimple
, heap
, else_stores
);
1646 /* Check that there are no read-after-write or write-after-write dependencies
1648 FOR_EACH_VEC_ELT (ddr_p
, else_ddrs
, i
, ddr
)
1650 struct data_reference
*dra
= DDR_A (ddr
);
1651 struct data_reference
*drb
= DDR_B (ddr
);
1653 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1654 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1655 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1656 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1657 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1658 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1660 free_dependence_relations (then_ddrs
);
1661 free_dependence_relations (else_ddrs
);
1662 free_data_refs (then_datarefs
);
1663 free_data_refs (else_datarefs
);
1664 VEC_free (gimple
, heap
, then_stores
);
1665 VEC_free (gimple
, heap
, else_stores
);
1670 /* Sink stores with same LHS. */
1671 FOR_EACH_VEC_ELT (gimple
, then_stores
, i
, then_store
)
1673 else_store
= VEC_index (gimple
, else_stores
, i
);
1674 res
= cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1675 then_store
, else_store
);
1679 free_dependence_relations (then_ddrs
);
1680 free_dependence_relations (else_ddrs
);
1681 free_data_refs (then_datarefs
);
1682 free_data_refs (else_datarefs
);
1683 VEC_free (gimple
, heap
, then_stores
);
1684 VEC_free (gimple
, heap
, else_stores
);
1689 /* Always do these optimizations if we have SSA
1690 trees to work on. */
1697 struct gimple_opt_pass pass_phiopt
=
1701 "phiopt", /* name */
1702 gate_phiopt
, /* gate */
1703 tree_ssa_phiopt
, /* execute */
1706 0, /* static_pass_number */
1707 TV_TREE_PHIOPT
, /* tv_id */
1708 PROP_cfg
| PROP_ssa
, /* properties_required */
1709 0, /* properties_provided */
1710 0, /* properties_destroyed */
1711 0, /* todo_flags_start */
1715 | TODO_verify_stmts
/* todo_flags_finish */
1722 return flag_tree_cselim
;
1725 struct gimple_opt_pass pass_cselim
=
1729 "cselim", /* name */
1730 gate_cselim
, /* gate */
1731 tree_ssa_cs_elim
, /* execute */
1734 0, /* static_pass_number */
1735 TV_TREE_PHIOPT
, /* tv_id */
1736 PROP_cfg
| PROP_ssa
, /* properties_required */
1737 0, /* properties_provided */
1738 0, /* properties_destroyed */
1739 0, /* todo_flags_start */
1743 | TODO_verify_stmts
/* todo_flags_finish */