1 /* Optimization of PHI nodes by converting them into straightline code.
2 Copyright (C) 2004-2013 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"
23 #include "hash-table.h"
29 #include "basic-block.h"
31 #include "tree-pass.h"
32 #include "langhooks.h"
33 #include "pointer-set.h"
36 #include "tree-data-ref.h"
37 #include "gimple-pretty-print.h"
38 #include "insn-config.h"
41 #include "tree-scalar-evolution.h"
43 #ifndef HAVE_conditional_move
44 #define HAVE_conditional_move (0)
47 static unsigned int tree_ssa_phiopt (void);
48 static unsigned int tree_ssa_phiopt_worker (bool, bool);
49 static bool conditional_replacement (basic_block
, basic_block
,
50 edge
, edge
, gimple
, tree
, tree
);
51 static int value_replacement (basic_block
, basic_block
,
52 edge
, edge
, gimple
, tree
, tree
);
53 static bool minmax_replacement (basic_block
, basic_block
,
54 edge
, edge
, gimple
, tree
, tree
);
55 static bool abs_replacement (basic_block
, basic_block
,
56 edge
, edge
, gimple
, tree
, tree
);
57 static bool cond_store_replacement (basic_block
, basic_block
, edge
, edge
,
58 struct pointer_set_t
*);
59 static bool cond_if_else_store_replacement (basic_block
, basic_block
, basic_block
);
60 static struct pointer_set_t
* get_non_trapping (void);
61 static void replace_phi_edge_with_variable (basic_block
, edge
, gimple
, tree
);
62 static void hoist_adjacent_loads (basic_block
, basic_block
,
63 basic_block
, basic_block
);
64 static bool gate_hoist_loads (void);
66 /* This pass tries to replaces an if-then-else block with an
67 assignment. We have four kinds of transformations. Some of these
68 transformations are also performed by the ifcvt RTL optimizer.
70 Conditional Replacement
71 -----------------------
73 This transformation, implemented in conditional_replacement,
77 if (cond) goto bb2; else goto bb1;
80 x = PHI <0 (bb1), 1 (bb0), ...>;
88 x = PHI <x' (bb0), ...>;
90 We remove bb1 as it becomes unreachable. This occurs often due to
91 gimplification of conditionals.
96 This transformation, implemented in value_replacement, replaces
99 if (a != b) goto bb2; else goto bb1;
102 x = PHI <a (bb1), b (bb0), ...>;
108 x = PHI <b (bb0), ...>;
110 This opportunity can sometimes occur as a result of other
114 Another case caught by value replacement looks like this:
120 if (t3 != 0) goto bb1; else goto bb2;
136 This transformation, implemented in abs_replacement, replaces
139 if (a >= 0) goto bb2; else goto bb1;
143 x = PHI <x (bb1), a (bb0), ...>;
150 x = PHI <x' (bb0), ...>;
155 This transformation, minmax_replacement replaces
158 if (a <= b) goto bb2; else goto bb1;
161 x = PHI <b (bb1), a (bb0), ...>;
168 x = PHI <x' (bb0), ...>;
170 A similar transformation is done for MAX_EXPR.
173 This pass also performs a fifth transformation of a slightly different
176 Adjacent Load Hoisting
177 ----------------------
179 This transformation replaces
182 if (...) goto bb2; else goto bb1;
184 x1 = (<expr>).field1;
187 x2 = (<expr>).field2;
194 x1 = (<expr>).field1;
195 x2 = (<expr>).field2;
196 if (...) goto bb2; else goto bb1;
203 The purpose of this transformation is to enable generation of conditional
204 move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
205 the loads is speculative, the transformation is restricted to very
206 specific cases to avoid introducing a page fault. We are looking for
214 where left and right are typically adjacent pointers in a tree structure. */
217 tree_ssa_phiopt (void)
219 return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
222 /* This pass tries to transform conditional stores into unconditional
223 ones, enabling further simplifications with the simpler then and else
224 blocks. In particular it replaces this:
227 if (cond) goto bb2; else goto bb1;
235 if (cond) goto bb1; else goto bb2;
239 condtmp = PHI <RHS, condtmp'>
242 This transformation can only be done under several constraints,
243 documented below. It also replaces:
246 if (cond) goto bb2; else goto bb1;
257 if (cond) goto bb3; else goto bb1;
260 condtmp = PHI <RHS1, RHS2>
264 tree_ssa_cs_elim (void)
267 /* ??? We are not interested in loop related info, but the following
268 will create it, ICEing as we didn't init loops with pre-headers.
269 An interfacing issue of find_data_references_in_bb. */
270 loop_optimizer_init (LOOPS_NORMAL
);
272 todo
= tree_ssa_phiopt_worker (true, false);
274 loop_optimizer_finalize ();
278 /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
281 single_non_singleton_phi_for_edges (gimple_seq seq
, edge e0
, edge e1
)
283 gimple_stmt_iterator i
;
285 if (gimple_seq_singleton_p (seq
))
286 return gsi_stmt (gsi_start (seq
));
287 for (i
= gsi_start (seq
); !gsi_end_p (i
); gsi_next (&i
))
289 gimple p
= gsi_stmt (i
);
290 /* If the PHI arguments are equal then we can skip this PHI. */
291 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p
, e0
->dest_idx
),
292 gimple_phi_arg_def (p
, e1
->dest_idx
)))
295 /* If we already have a PHI that has the two edge arguments are
296 different, then return it is not a singleton for these PHIs. */
305 /* The core routine of conditional store replacement and normal
306 phi optimizations. Both share much of the infrastructure in how
307 to match applicable basic block patterns. DO_STORE_ELIM is true
308 when we want to do conditional store replacement, false otherwise.
309 DO_HOIST_LOADS is true when we want to hoist adjacent loads out
310 of diamond control flow patterns, false otherwise. */
312 tree_ssa_phiopt_worker (bool do_store_elim
, bool do_hoist_loads
)
315 basic_block
*bb_order
;
317 bool cfgchanged
= false;
318 struct pointer_set_t
*nontrap
= 0;
321 /* Calculate the set of non-trapping memory accesses. */
322 nontrap
= get_non_trapping ();
324 /* Search every basic block for COND_EXPR we may be able to optimize.
326 We walk the blocks in order that guarantees that a block with
327 a single predecessor is processed before the predecessor.
328 This ensures that we collapse inner ifs before visiting the
329 outer ones, and also that we do not try to visit a removed
331 bb_order
= single_pred_before_succ_order ();
332 n
= n_basic_blocks
- NUM_FIXED_BLOCKS
;
334 for (i
= 0; i
< n
; i
++)
336 gimple cond_stmt
, phi
;
337 basic_block bb1
, bb2
;
343 cond_stmt
= last_stmt (bb
);
344 /* Check to see if the last statement is a GIMPLE_COND. */
346 || gimple_code (cond_stmt
) != GIMPLE_COND
)
349 e1
= EDGE_SUCC (bb
, 0);
351 e2
= EDGE_SUCC (bb
, 1);
354 /* We cannot do the optimization on abnormal edges. */
355 if ((e1
->flags
& EDGE_ABNORMAL
) != 0
356 || (e2
->flags
& EDGE_ABNORMAL
) != 0)
359 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
360 if (EDGE_COUNT (bb1
->succs
) == 0
362 || EDGE_COUNT (bb2
->succs
) == 0)
365 /* Find the bb which is the fall through to the other. */
366 if (EDGE_SUCC (bb1
, 0)->dest
== bb2
)
368 else if (EDGE_SUCC (bb2
, 0)->dest
== bb1
)
370 basic_block bb_tmp
= bb1
;
377 else if (do_store_elim
378 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
380 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
382 if (!single_succ_p (bb1
)
383 || (EDGE_SUCC (bb1
, 0)->flags
& EDGE_FALLTHRU
) == 0
384 || !single_succ_p (bb2
)
385 || (EDGE_SUCC (bb2
, 0)->flags
& EDGE_FALLTHRU
) == 0
386 || EDGE_COUNT (bb3
->preds
) != 2)
388 if (cond_if_else_store_replacement (bb1
, bb2
, bb3
))
392 else if (do_hoist_loads
393 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
395 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
397 if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt
)))
398 && single_succ_p (bb1
)
399 && single_succ_p (bb2
)
400 && single_pred_p (bb1
)
401 && single_pred_p (bb2
)
402 && EDGE_COUNT (bb
->succs
) == 2
403 && EDGE_COUNT (bb3
->preds
) == 2
404 /* If one edge or the other is dominant, a conditional move
405 is likely to perform worse than the well-predicted branch. */
406 && !predictable_edge_p (EDGE_SUCC (bb
, 0))
407 && !predictable_edge_p (EDGE_SUCC (bb
, 1)))
408 hoist_adjacent_loads (bb
, bb1
, bb2
, bb3
);
414 e1
= EDGE_SUCC (bb1
, 0);
416 /* Make sure that bb1 is just a fall through. */
417 if (!single_succ_p (bb1
)
418 || (e1
->flags
& EDGE_FALLTHRU
) == 0)
421 /* Also make sure that bb1 only have one predecessor and that it
423 if (!single_pred_p (bb1
)
424 || single_pred (bb1
) != bb
)
429 /* bb1 is the middle block, bb2 the join block, bb the split block,
430 e1 the fallthrough edge from bb1 to bb2. We can't do the
431 optimization if the join block has more than two predecessors. */
432 if (EDGE_COUNT (bb2
->preds
) > 2)
434 if (cond_store_replacement (bb1
, bb2
, e1
, e2
, nontrap
))
439 gimple_seq phis
= phi_nodes (bb2
);
440 gimple_stmt_iterator gsi
;
441 bool candorest
= true;
443 /* Value replacement can work with more than one PHI
444 so try that first. */
445 for (gsi
= gsi_start (phis
); !gsi_end_p (gsi
); gsi_next (&gsi
))
447 phi
= gsi_stmt (gsi
);
448 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
449 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
450 if (value_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
) == 2)
461 phi
= single_non_singleton_phi_for_edges (phis
, e1
, e2
);
465 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
466 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
468 /* Something is wrong if we cannot find the arguments in the PHI
470 gcc_assert (arg0
!= NULL
&& arg1
!= NULL
);
472 /* Do the replacement of conditional if it can be done. */
473 if (conditional_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
475 else if (abs_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
477 else if (minmax_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
485 pointer_set_destroy (nontrap
);
486 /* If the CFG has changed, we should cleanup the CFG. */
487 if (cfgchanged
&& do_store_elim
)
489 /* In cond-store replacement we have added some loads on edges
490 and new VOPS (as we moved the store, and created a load). */
491 gsi_commit_edge_inserts ();
492 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
495 return TODO_cleanup_cfg
;
499 /* Replace PHI node element whose edge is E in block BB with variable NEW.
500 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
501 is known to have two edges, one of which must reach BB). */
504 replace_phi_edge_with_variable (basic_block cond_block
,
505 edge e
, gimple phi
, tree new_tree
)
507 basic_block bb
= gimple_bb (phi
);
508 basic_block block_to_remove
;
509 gimple_stmt_iterator gsi
;
511 /* Change the PHI argument to new. */
512 SET_USE (PHI_ARG_DEF_PTR (phi
, e
->dest_idx
), new_tree
);
514 /* Remove the empty basic block. */
515 if (EDGE_SUCC (cond_block
, 0)->dest
== bb
)
517 EDGE_SUCC (cond_block
, 0)->flags
|= EDGE_FALLTHRU
;
518 EDGE_SUCC (cond_block
, 0)->flags
&= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
519 EDGE_SUCC (cond_block
, 0)->probability
= REG_BR_PROB_BASE
;
520 EDGE_SUCC (cond_block
, 0)->count
+= EDGE_SUCC (cond_block
, 1)->count
;
522 block_to_remove
= EDGE_SUCC (cond_block
, 1)->dest
;
526 EDGE_SUCC (cond_block
, 1)->flags
|= EDGE_FALLTHRU
;
527 EDGE_SUCC (cond_block
, 1)->flags
528 &= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
529 EDGE_SUCC (cond_block
, 1)->probability
= REG_BR_PROB_BASE
;
530 EDGE_SUCC (cond_block
, 1)->count
+= EDGE_SUCC (cond_block
, 0)->count
;
532 block_to_remove
= EDGE_SUCC (cond_block
, 0)->dest
;
534 delete_basic_block (block_to_remove
);
536 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
537 gsi
= gsi_last_bb (cond_block
);
538 gsi_remove (&gsi
, true);
540 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
542 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
547 /* The function conditional_replacement does the main work of doing the
548 conditional replacement. Return true if the replacement is done.
549 Otherwise return false.
550 BB is the basic block where the replacement is going to be done on. ARG0
551 is argument 0 from PHI. Likewise for ARG1. */
554 conditional_replacement (basic_block cond_bb
, basic_block middle_bb
,
555 edge e0
, edge e1
, gimple phi
,
556 tree arg0
, tree arg1
)
559 gimple stmt
, new_stmt
;
561 gimple_stmt_iterator gsi
;
562 edge true_edge
, false_edge
;
563 tree new_var
, new_var2
;
566 /* FIXME: Gimplification of complex type is too hard for now. */
567 /* We aren't prepared to handle vectors either (and it is a question
568 if it would be worthwhile anyway). */
569 if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
570 || POINTER_TYPE_P (TREE_TYPE (arg0
)))
571 || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1
))
572 || POINTER_TYPE_P (TREE_TYPE (arg1
))))
575 /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
576 convert it to the conditional. */
577 if ((integer_zerop (arg0
) && integer_onep (arg1
))
578 || (integer_zerop (arg1
) && integer_onep (arg0
)))
580 else if ((integer_zerop (arg0
) && integer_all_onesp (arg1
))
581 || (integer_zerop (arg1
) && integer_all_onesp (arg0
)))
586 if (!empty_block_p (middle_bb
))
589 /* At this point we know we have a GIMPLE_COND with two successors.
590 One successor is BB, the other successor is an empty block which
591 falls through into BB.
593 There is a single PHI node at the join point (BB) and its arguments
594 are constants (0, 1) or (0, -1).
596 So, given the condition COND, and the two PHI arguments, we can
597 rewrite this PHI into non-branching code:
599 dest = (COND) or dest = COND'
601 We use the condition as-is if the argument associated with the
602 true edge has the value one or the argument associated with the
603 false edge as the value zero. Note that those conditions are not
604 the same since only one of the outgoing edges from the GIMPLE_COND
605 will directly reach BB and thus be associated with an argument. */
607 stmt
= last_stmt (cond_bb
);
608 result
= PHI_RESULT (phi
);
610 /* To handle special cases like floating point comparison, it is easier and
611 less error-prone to build a tree and gimplify it on the fly though it is
613 cond
= fold_build2_loc (gimple_location (stmt
),
614 gimple_cond_code (stmt
), boolean_type_node
,
615 gimple_cond_lhs (stmt
), gimple_cond_rhs (stmt
));
617 /* We need to know which is the true edge and which is the false
618 edge so that we know when to invert the condition below. */
619 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
620 if ((e0
== true_edge
&& integer_zerop (arg0
))
621 || (e0
== false_edge
&& !integer_zerop (arg0
))
622 || (e1
== true_edge
&& integer_zerop (arg1
))
623 || (e1
== false_edge
&& !integer_zerop (arg1
)))
624 cond
= fold_build1_loc (gimple_location (stmt
),
625 TRUTH_NOT_EXPR
, TREE_TYPE (cond
), cond
);
629 cond
= fold_convert_loc (gimple_location (stmt
),
630 TREE_TYPE (result
), cond
);
631 cond
= fold_build1_loc (gimple_location (stmt
),
632 NEGATE_EXPR
, TREE_TYPE (cond
), cond
);
635 /* Insert our new statements at the end of conditional block before the
637 gsi
= gsi_for_stmt (stmt
);
638 new_var
= force_gimple_operand_gsi (&gsi
, cond
, true, NULL
, true,
641 if (!useless_type_conversion_p (TREE_TYPE (result
), TREE_TYPE (new_var
)))
643 source_location locus_0
, locus_1
;
645 new_var2
= make_ssa_name (TREE_TYPE (result
), NULL
);
646 new_stmt
= gimple_build_assign_with_ops (CONVERT_EXPR
, new_var2
,
648 gsi_insert_before (&gsi
, new_stmt
, GSI_SAME_STMT
);
651 /* Set the locus to the first argument, unless is doesn't have one. */
652 locus_0
= gimple_phi_arg_location (phi
, 0);
653 locus_1
= gimple_phi_arg_location (phi
, 1);
654 if (locus_0
== UNKNOWN_LOCATION
)
656 gimple_set_location (new_stmt
, locus_0
);
659 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_var
);
661 /* Note that we optimized this PHI. */
665 /* Update *ARG which is defined in STMT so that it contains the
666 computed value if that seems profitable. Return true if the
667 statement is made dead by that rewriting. */
670 jump_function_from_stmt (tree
*arg
, gimple stmt
)
672 enum tree_code code
= gimple_assign_rhs_code (stmt
);
673 if (code
== ADDR_EXPR
)
675 /* For arg = &p->i transform it to p, if possible. */
676 tree rhs1
= gimple_assign_rhs1 (stmt
);
677 HOST_WIDE_INT offset
;
678 tree tem
= get_addr_base_and_unit_offset (TREE_OPERAND (rhs1
, 0),
681 && TREE_CODE (tem
) == MEM_REF
682 && (mem_ref_offset (tem
) + double_int::from_shwi (offset
)).is_zero ())
684 *arg
= TREE_OPERAND (tem
, 0);
688 /* TODO: Much like IPA-CP jump-functions we want to handle constant
689 additions symbolically here, and we'd need to update the comparison
690 code that compares the arg + cst tuples in our caller. For now the
691 code above exactly handles the VEC_BASE pattern from vec.h. */
695 /* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
696 of the form SSA_NAME NE 0.
698 If RHS is fed by a simple EQ_EXPR comparison of two values, see if
699 the two input values of the EQ_EXPR match arg0 and arg1.
701 If so update *code and return TRUE. Otherwise return FALSE. */
704 rhs_is_fed_for_value_replacement (const_tree arg0
, const_tree arg1
,
705 enum tree_code
*code
, const_tree rhs
)
707 /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
709 if (TREE_CODE (rhs
) == SSA_NAME
)
711 gimple def1
= SSA_NAME_DEF_STMT (rhs
);
713 /* Verify the defining statement has an EQ_EXPR on the RHS. */
714 if (is_gimple_assign (def1
) && gimple_assign_rhs_code (def1
) == EQ_EXPR
)
716 /* Finally verify the source operands of the EQ_EXPR are equal
718 tree op0
= gimple_assign_rhs1 (def1
);
719 tree op1
= gimple_assign_rhs2 (def1
);
720 if ((operand_equal_for_phi_arg_p (arg0
, op0
)
721 && operand_equal_for_phi_arg_p (arg1
, op1
))
722 || (operand_equal_for_phi_arg_p (arg0
, op1
)
723 && operand_equal_for_phi_arg_p (arg1
, op0
)))
725 /* We will perform the optimization. */
726 *code
= gimple_assign_rhs_code (def1
);
734 /* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
736 Also return TRUE if arg0/arg1 are equal to the source arguments of a
737 an EQ comparison feeding a BIT_AND_EXPR which feeds COND.
739 Return FALSE otherwise. */
742 operand_equal_for_value_replacement (const_tree arg0
, const_tree arg1
,
743 enum tree_code
*code
, gimple cond
)
746 tree lhs
= gimple_cond_lhs (cond
);
747 tree rhs
= gimple_cond_rhs (cond
);
749 if ((operand_equal_for_phi_arg_p (arg0
, lhs
)
750 && operand_equal_for_phi_arg_p (arg1
, rhs
))
751 || (operand_equal_for_phi_arg_p (arg1
, lhs
)
752 && operand_equal_for_phi_arg_p (arg0
, rhs
)))
755 /* Now handle more complex case where we have an EQ comparison
756 which feeds a BIT_AND_EXPR which feeds COND.
758 First verify that COND is of the form SSA_NAME NE 0. */
759 if (*code
!= NE_EXPR
|| !integer_zerop (rhs
)
760 || TREE_CODE (lhs
) != SSA_NAME
)
763 /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */
764 def
= SSA_NAME_DEF_STMT (lhs
);
765 if (!is_gimple_assign (def
) || gimple_assign_rhs_code (def
) != BIT_AND_EXPR
)
768 /* Now verify arg0/arg1 correspond to the source arguments of an
769 EQ comparison feeding the BIT_AND_EXPR. */
771 tree tmp
= gimple_assign_rhs1 (def
);
772 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
775 tmp
= gimple_assign_rhs2 (def
);
776 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
782 /* The function value_replacement does the main work of doing the value
783 replacement. Return non-zero if the replacement is done. Otherwise return
784 0. If we remove the middle basic block, return 2.
785 BB is the basic block where the replacement is going to be done on. ARG0
786 is argument 0 from the PHI. Likewise for ARG1. */
789 value_replacement (basic_block cond_bb
, basic_block middle_bb
,
790 edge e0
, edge e1
, gimple phi
,
791 tree arg0
, tree arg1
)
793 gimple_stmt_iterator gsi
;
795 edge true_edge
, false_edge
;
797 bool emtpy_or_with_defined_p
= true;
799 /* If the type says honor signed zeros we cannot do this
801 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
804 /* If there is a statement in MIDDLE_BB that defines one of the PHI
805 arguments, then adjust arg0 or arg1. */
806 gsi
= gsi_after_labels (middle_bb
);
807 if (!gsi_end_p (gsi
) && is_gimple_debug (gsi_stmt (gsi
)))
808 gsi_next_nondebug (&gsi
);
809 while (!gsi_end_p (gsi
))
811 gimple stmt
= gsi_stmt (gsi
);
813 gsi_next_nondebug (&gsi
);
814 if (!is_gimple_assign (stmt
))
816 emtpy_or_with_defined_p
= false;
819 /* Now try to adjust arg0 or arg1 according to the computation
821 lhs
= gimple_assign_lhs (stmt
);
823 && jump_function_from_stmt (&arg0
, stmt
))
825 && jump_function_from_stmt (&arg1
, stmt
)))
826 emtpy_or_with_defined_p
= false;
829 cond
= last_stmt (cond_bb
);
830 code
= gimple_cond_code (cond
);
832 /* This transformation is only valid for equality comparisons. */
833 if (code
!= NE_EXPR
&& code
!= EQ_EXPR
)
836 /* We need to know which is the true edge and which is the false
837 edge so that we know if have abs or negative abs. */
838 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
840 /* At this point we know we have a COND_EXPR with two successors.
841 One successor is BB, the other successor is an empty block which
842 falls through into BB.
844 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
846 There is a single PHI node at the join point (BB) with two arguments.
848 We now need to verify that the two arguments in the PHI node match
849 the two arguments to the equality comparison. */
851 if (operand_equal_for_value_replacement (arg0
, arg1
, &code
, cond
))
856 /* For NE_EXPR, we want to build an assignment result = arg where
857 arg is the PHI argument associated with the true edge. For
858 EQ_EXPR we want the PHI argument associated with the false edge. */
859 e
= (code
== NE_EXPR
? true_edge
: false_edge
);
861 /* Unfortunately, E may not reach BB (it may instead have gone to
862 OTHER_BLOCK). If that is the case, then we want the single outgoing
863 edge from OTHER_BLOCK which reaches BB and represents the desired
864 path from COND_BLOCK. */
865 if (e
->dest
== middle_bb
)
866 e
= single_succ_edge (e
->dest
);
868 /* Now we know the incoming edge to BB that has the argument for the
869 RHS of our new assignment statement. */
875 /* If the middle basic block was empty or is defining the
876 PHI arguments and this is a single phi where the args are different
877 for the edges e0 and e1 then we can remove the middle basic block. */
878 if (emtpy_or_with_defined_p
879 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)),
882 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, arg
);
883 /* Note that we optimized this PHI. */
888 /* Replace the PHI arguments with arg. */
889 SET_PHI_ARG_DEF (phi
, e0
->dest_idx
, arg
);
890 SET_PHI_ARG_DEF (phi
, e1
->dest_idx
, arg
);
891 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
893 fprintf (dump_file
, "PHI ");
894 print_generic_expr (dump_file
, gimple_phi_result (phi
), 0);
895 fprintf (dump_file
, " reduced for COND_EXPR in block %d to ",
897 print_generic_expr (dump_file
, arg
, 0);
898 fprintf (dump_file
, ".\n");
907 /* The function minmax_replacement does the main work of doing the minmax
908 replacement. Return true if the replacement is done. Otherwise return
910 BB is the basic block where the replacement is going to be done on. ARG0
911 is argument 0 from the PHI. Likewise for ARG1. */
914 minmax_replacement (basic_block cond_bb
, basic_block middle_bb
,
915 edge e0
, edge e1
, gimple phi
,
916 tree arg0
, tree arg1
)
919 gimple cond
, new_stmt
;
920 edge true_edge
, false_edge
;
921 enum tree_code cmp
, minmax
, ass_code
;
922 tree smaller
, larger
, arg_true
, arg_false
;
923 gimple_stmt_iterator gsi
, gsi_from
;
925 type
= TREE_TYPE (PHI_RESULT (phi
));
927 /* The optimization may be unsafe due to NaNs. */
928 if (HONOR_NANS (TYPE_MODE (type
)))
931 cond
= last_stmt (cond_bb
);
932 cmp
= gimple_cond_code (cond
);
934 /* This transformation is only valid for order comparisons. Record which
935 operand is smaller/larger if the result of the comparison is true. */
936 if (cmp
== LT_EXPR
|| cmp
== LE_EXPR
)
938 smaller
= gimple_cond_lhs (cond
);
939 larger
= gimple_cond_rhs (cond
);
941 else if (cmp
== GT_EXPR
|| cmp
== GE_EXPR
)
943 smaller
= gimple_cond_rhs (cond
);
944 larger
= gimple_cond_lhs (cond
);
949 /* We need to know which is the true edge and which is the false
950 edge so that we know if have abs or negative abs. */
951 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
953 /* Forward the edges over the middle basic block. */
954 if (true_edge
->dest
== middle_bb
)
955 true_edge
= EDGE_SUCC (true_edge
->dest
, 0);
956 if (false_edge
->dest
== middle_bb
)
957 false_edge
= EDGE_SUCC (false_edge
->dest
, 0);
961 gcc_assert (false_edge
== e1
);
967 gcc_assert (false_edge
== e0
);
968 gcc_assert (true_edge
== e1
);
973 if (empty_block_p (middle_bb
))
975 if (operand_equal_for_phi_arg_p (arg_true
, smaller
)
976 && operand_equal_for_phi_arg_p (arg_false
, larger
))
980 if (smaller < larger)
986 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
)
987 && operand_equal_for_phi_arg_p (arg_true
, larger
))
994 /* Recognize the following case, assuming d <= u:
1000 This is equivalent to
1005 gimple assign
= last_and_only_stmt (middle_bb
);
1006 tree lhs
, op0
, op1
, bound
;
1009 || gimple_code (assign
) != GIMPLE_ASSIGN
)
1012 lhs
= gimple_assign_lhs (assign
);
1013 ass_code
= gimple_assign_rhs_code (assign
);
1014 if (ass_code
!= MAX_EXPR
&& ass_code
!= MIN_EXPR
)
1016 op0
= gimple_assign_rhs1 (assign
);
1017 op1
= gimple_assign_rhs2 (assign
);
1019 if (true_edge
->src
== middle_bb
)
1021 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
1022 if (!operand_equal_for_phi_arg_p (lhs
, arg_true
))
1025 if (operand_equal_for_phi_arg_p (arg_false
, larger
))
1029 if (smaller < larger)
1031 r' = MAX_EXPR (smaller, bound)
1033 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
1034 if (ass_code
!= MAX_EXPR
)
1038 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1040 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1045 /* We need BOUND <= LARGER. */
1046 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1050 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
))
1054 if (smaller < larger)
1056 r' = MIN_EXPR (larger, bound)
1058 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
1059 if (ass_code
!= MIN_EXPR
)
1063 if (operand_equal_for_phi_arg_p (op0
, larger
))
1065 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1070 /* We need BOUND >= SMALLER. */
1071 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1080 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
1081 if (!operand_equal_for_phi_arg_p (lhs
, arg_false
))
1084 if (operand_equal_for_phi_arg_p (arg_true
, larger
))
1088 if (smaller > larger)
1090 r' = MIN_EXPR (smaller, bound)
1092 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
1093 if (ass_code
!= MIN_EXPR
)
1097 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1099 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1104 /* We need BOUND >= LARGER. */
1105 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1109 else if (operand_equal_for_phi_arg_p (arg_true
, smaller
))
1113 if (smaller > larger)
1115 r' = MAX_EXPR (larger, bound)
1117 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
1118 if (ass_code
!= MAX_EXPR
)
1122 if (operand_equal_for_phi_arg_p (op0
, larger
))
1124 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1129 /* We need BOUND <= SMALLER. */
1130 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1138 /* Move the statement from the middle block. */
1139 gsi
= gsi_last_bb (cond_bb
);
1140 gsi_from
= gsi_last_nondebug_bb (middle_bb
);
1141 gsi_move_before (&gsi_from
, &gsi
);
1144 /* Emit the statement to compute min/max. */
1145 result
= duplicate_ssa_name (PHI_RESULT (phi
), NULL
);
1146 new_stmt
= gimple_build_assign_with_ops (minmax
, result
, arg0
, arg1
);
1147 gsi
= gsi_last_bb (cond_bb
);
1148 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1150 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1154 /* The function absolute_replacement does the main work of doing the absolute
1155 replacement. Return true if the replacement is done. Otherwise return
1157 bb is the basic block where the replacement is going to be done on. arg0
1158 is argument 0 from the phi. Likewise for arg1. */
1161 abs_replacement (basic_block cond_bb
, basic_block middle_bb
,
1162 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1163 gimple phi
, tree arg0
, tree arg1
)
1166 gimple new_stmt
, cond
;
1167 gimple_stmt_iterator gsi
;
1168 edge true_edge
, false_edge
;
1173 enum tree_code cond_code
;
1175 /* If the type says honor signed zeros we cannot do this
1177 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
1180 /* OTHER_BLOCK must have only one executable statement which must have the
1181 form arg0 = -arg1 or arg1 = -arg0. */
1183 assign
= last_and_only_stmt (middle_bb
);
1184 /* If we did not find the proper negation assignment, then we can not
1189 /* If we got here, then we have found the only executable statement
1190 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1191 arg1 = -arg0, then we can not optimize. */
1192 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1195 lhs
= gimple_assign_lhs (assign
);
1197 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1200 rhs
= gimple_assign_rhs1 (assign
);
1202 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1203 if (!(lhs
== arg0
&& rhs
== arg1
)
1204 && !(lhs
== arg1
&& rhs
== arg0
))
1207 cond
= last_stmt (cond_bb
);
1208 result
= PHI_RESULT (phi
);
1210 /* Only relationals comparing arg[01] against zero are interesting. */
1211 cond_code
= gimple_cond_code (cond
);
1212 if (cond_code
!= GT_EXPR
&& cond_code
!= GE_EXPR
1213 && cond_code
!= LT_EXPR
&& cond_code
!= LE_EXPR
)
1216 /* Make sure the conditional is arg[01] OP y. */
1217 if (gimple_cond_lhs (cond
) != rhs
)
1220 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond
)))
1221 ? real_zerop (gimple_cond_rhs (cond
))
1222 : integer_zerop (gimple_cond_rhs (cond
)))
1227 /* We need to know which is the true edge and which is the false
1228 edge so that we know if have abs or negative abs. */
1229 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1231 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1232 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1233 the false edge goes to OTHER_BLOCK. */
1234 if (cond_code
== GT_EXPR
|| cond_code
== GE_EXPR
)
1239 if (e
->dest
== middle_bb
)
1244 result
= duplicate_ssa_name (result
, NULL
);
1247 lhs
= make_ssa_name (TREE_TYPE (result
), NULL
);
1251 /* Build the modify expression with abs expression. */
1252 new_stmt
= gimple_build_assign_with_ops (ABS_EXPR
, lhs
, rhs
, NULL
);
1254 gsi
= gsi_last_bb (cond_bb
);
1255 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1259 /* Get the right GSI. We want to insert after the recently
1260 added ABS_EXPR statement (which we know is the first statement
1262 new_stmt
= gimple_build_assign_with_ops (NEGATE_EXPR
, result
, lhs
, NULL
);
1264 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1267 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1269 /* Note that we optimized this PHI. */
1273 /* Auxiliary functions to determine the set of memory accesses which
1274 can't trap because they are preceded by accesses to the same memory
1275 portion. We do that for MEM_REFs, so we only need to track
1276 the SSA_NAME of the pointer indirectly referenced. The algorithm
1277 simply is a walk over all instructions in dominator order. When
1278 we see an MEM_REF we determine if we've already seen a same
1279 ref anywhere up to the root of the dominator tree. If we do the
1280 current access can't trap. If we don't see any dominating access
1281 the current access might trap, but might also make later accesses
1282 non-trapping, so we remember it. We need to be careful with loads
1283 or stores, for instance a load might not trap, while a store would,
1284 so if we see a dominating read access this doesn't mean that a later
1285 write access would not trap. Hence we also need to differentiate the
1286 type of access(es) seen.
1288 ??? We currently are very conservative and assume that a load might
1289 trap even if a store doesn't (write-only memory). This probably is
1290 overly conservative. */
1292 /* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1293 through it was seen, which would constitute a no-trap region for
1297 unsigned int ssa_name_ver
;
1300 HOST_WIDE_INT offset
, size
;
1304 /* Hashtable helpers. */
1306 struct ssa_names_hasher
: typed_free_remove
<name_to_bb
>
1308 typedef name_to_bb value_type
;
1309 typedef name_to_bb compare_type
;
1310 static inline hashval_t
hash (const value_type
*);
1311 static inline bool equal (const value_type
*, const compare_type
*);
1314 /* Used for quick clearing of the hash-table when we see calls.
1315 Hash entries with phase < nt_call_phase are invalid. */
1316 static unsigned int nt_call_phase
;
1318 /* The hash function. */
1321 ssa_names_hasher::hash (const value_type
*n
)
1323 return n
->ssa_name_ver
^ (((hashval_t
) n
->store
) << 31)
1324 ^ (n
->offset
<< 6) ^ (n
->size
<< 3);
1327 /* The equality function of *P1 and *P2. */
1330 ssa_names_hasher::equal (const value_type
*n1
, const compare_type
*n2
)
1332 return n1
->ssa_name_ver
== n2
->ssa_name_ver
1333 && n1
->store
== n2
->store
1334 && n1
->offset
== n2
->offset
1335 && n1
->size
== n2
->size
;
1338 /* The hash table for remembering what we've seen. */
1339 static hash_table
<ssa_names_hasher
> seen_ssa_names
;
1341 /* We see the expression EXP in basic block BB. If it's an interesting
1342 expression (an MEM_REF through an SSA_NAME) possibly insert the
1343 expression into the set NONTRAP or the hash table of seen expressions.
1344 STORE is true if this expression is on the LHS, otherwise it's on
1347 add_or_mark_expr (basic_block bb
, tree exp
,
1348 struct pointer_set_t
*nontrap
, bool store
)
1352 if (TREE_CODE (exp
) == MEM_REF
1353 && TREE_CODE (TREE_OPERAND (exp
, 0)) == SSA_NAME
1354 && host_integerp (TREE_OPERAND (exp
, 1), 0)
1355 && (size
= int_size_in_bytes (TREE_TYPE (exp
))) > 0)
1357 tree name
= TREE_OPERAND (exp
, 0);
1358 struct name_to_bb map
;
1360 struct name_to_bb
*n2bb
;
1361 basic_block found_bb
= 0;
1363 /* Try to find the last seen MEM_REF through the same
1364 SSA_NAME, which can trap. */
1365 map
.ssa_name_ver
= SSA_NAME_VERSION (name
);
1369 map
.offset
= tree_low_cst (TREE_OPERAND (exp
, 1), 0);
1372 slot
= seen_ssa_names
.find_slot (&map
, INSERT
);
1374 if (n2bb
&& n2bb
->phase
>= nt_call_phase
)
1375 found_bb
= n2bb
->bb
;
1377 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1378 (it's in a basic block on the path from us to the dominator root)
1379 then we can't trap. */
1380 if (found_bb
&& (((size_t)found_bb
->aux
) & 1) == 1)
1382 pointer_set_insert (nontrap
, exp
);
1386 /* EXP might trap, so insert it into the hash table. */
1389 n2bb
->phase
= nt_call_phase
;
1394 n2bb
= XNEW (struct name_to_bb
);
1395 n2bb
->ssa_name_ver
= SSA_NAME_VERSION (name
);
1396 n2bb
->phase
= nt_call_phase
;
1398 n2bb
->store
= store
;
1399 n2bb
->offset
= map
.offset
;
1407 class nontrapping_dom_walker
: public dom_walker
1410 nontrapping_dom_walker (cdi_direction direction
, pointer_set_t
*ps
)
1411 : dom_walker (direction
), m_nontrapping (ps
) {}
1413 virtual void before_dom_children (basic_block
);
1414 virtual void after_dom_children (basic_block
);
1417 pointer_set_t
*m_nontrapping
;
1420 /* Called by walk_dominator_tree, when entering the block BB. */
1422 nontrapping_dom_walker::before_dom_children (basic_block bb
)
1426 gimple_stmt_iterator gsi
;
1428 /* If we haven't seen all our predecessors, clear the hash-table. */
1429 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1430 if ((((size_t)e
->src
->aux
) & 2) == 0)
1436 /* Mark this BB as being on the path to dominator root and as visited. */
1437 bb
->aux
= (void*)(1 | 2);
1439 /* And walk the statements in order. */
1440 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1442 gimple stmt
= gsi_stmt (gsi
);
1444 if (is_gimple_call (stmt
) && !nonfreeing_call_p (stmt
))
1446 else if (gimple_assign_single_p (stmt
) && !gimple_has_volatile_ops (stmt
))
1448 add_or_mark_expr (bb
, gimple_assign_lhs (stmt
), m_nontrapping
, true);
1449 add_or_mark_expr (bb
, gimple_assign_rhs1 (stmt
), m_nontrapping
, false);
1454 /* Called by walk_dominator_tree, when basic block BB is exited. */
1456 nontrapping_dom_walker::after_dom_children (basic_block bb
)
1458 /* This BB isn't on the path to dominator root anymore. */
1462 /* This is the entry point of gathering non trapping memory accesses.
1463 It will do a dominator walk over the whole function, and it will
1464 make use of the bb->aux pointers. It returns a set of trees
1465 (the MEM_REFs itself) which can't trap. */
1466 static struct pointer_set_t
*
1467 get_non_trapping (void)
1470 pointer_set_t
*nontrap
= pointer_set_create ();
1471 seen_ssa_names
.create (128);
1472 /* We're going to do a dominator walk, so ensure that we have
1473 dominance information. */
1474 calculate_dominance_info (CDI_DOMINATORS
);
1476 nontrapping_dom_walker (CDI_DOMINATORS
, nontrap
)
1477 .walk (cfun
->cfg
->x_entry_block_ptr
);
1479 seen_ssa_names
.dispose ();
1481 clear_aux_for_blocks ();
1485 /* Do the main work of conditional store replacement. We already know
1486 that the recognized pattern looks like so:
1489 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1492 fallthrough (edge E0)
1496 We check that MIDDLE_BB contains only one store, that that store
1497 doesn't trap (not via NOTRAP, but via checking if an access to the same
1498 memory location dominates us) and that the store has a "simple" RHS. */
1501 cond_store_replacement (basic_block middle_bb
, basic_block join_bb
,
1502 edge e0
, edge e1
, struct pointer_set_t
*nontrap
)
1504 gimple assign
= last_and_only_stmt (middle_bb
);
1505 tree lhs
, rhs
, name
, name2
;
1506 gimple newphi
, new_stmt
;
1507 gimple_stmt_iterator gsi
;
1508 source_location locus
;
1510 /* Check if middle_bb contains of only one store. */
1512 || !gimple_assign_single_p (assign
)
1513 || gimple_has_volatile_ops (assign
))
1516 locus
= gimple_location (assign
);
1517 lhs
= gimple_assign_lhs (assign
);
1518 rhs
= gimple_assign_rhs1 (assign
);
1519 if (TREE_CODE (lhs
) != MEM_REF
1520 || TREE_CODE (TREE_OPERAND (lhs
, 0)) != SSA_NAME
1521 || !is_gimple_reg_type (TREE_TYPE (lhs
)))
1524 /* Prove that we can move the store down. We could also check
1525 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1526 whose value is not available readily, which we want to avoid. */
1527 if (!pointer_set_contains (nontrap
, lhs
))
1530 /* Now we've checked the constraints, so do the transformation:
1531 1) Remove the single store. */
1532 gsi
= gsi_for_stmt (assign
);
1533 unlink_stmt_vdef (assign
);
1534 gsi_remove (&gsi
, true);
1535 release_defs (assign
);
1537 /* 2) Insert a load from the memory of the store to the temporary
1538 on the edge which did not contain the store. */
1539 lhs
= unshare_expr (lhs
);
1540 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1541 new_stmt
= gimple_build_assign (name
, lhs
);
1542 gimple_set_location (new_stmt
, locus
);
1543 gsi_insert_on_edge (e1
, new_stmt
);
1545 /* 3) Create a PHI node at the join block, with one argument
1546 holding the old RHS, and the other holding the temporary
1547 where we stored the old memory contents. */
1548 name2
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1549 newphi
= create_phi_node (name2
, join_bb
);
1550 add_phi_arg (newphi
, rhs
, e0
, locus
);
1551 add_phi_arg (newphi
, name
, e1
, locus
);
1553 lhs
= unshare_expr (lhs
);
1554 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1556 /* 4) Insert that PHI node. */
1557 gsi
= gsi_after_labels (join_bb
);
1558 if (gsi_end_p (gsi
))
1560 gsi
= gsi_last_bb (join_bb
);
1561 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1564 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1569 /* Do the main work of conditional store replacement. */
1572 cond_if_else_store_replacement_1 (basic_block then_bb
, basic_block else_bb
,
1573 basic_block join_bb
, gimple then_assign
,
1576 tree lhs_base
, lhs
, then_rhs
, else_rhs
, name
;
1577 source_location then_locus
, else_locus
;
1578 gimple_stmt_iterator gsi
;
1579 gimple newphi
, new_stmt
;
1581 if (then_assign
== NULL
1582 || !gimple_assign_single_p (then_assign
)
1583 || gimple_clobber_p (then_assign
)
1584 || gimple_has_volatile_ops (then_assign
)
1585 || else_assign
== NULL
1586 || !gimple_assign_single_p (else_assign
)
1587 || gimple_clobber_p (else_assign
)
1588 || gimple_has_volatile_ops (else_assign
))
1591 lhs
= gimple_assign_lhs (then_assign
);
1592 if (!is_gimple_reg_type (TREE_TYPE (lhs
))
1593 || !operand_equal_p (lhs
, gimple_assign_lhs (else_assign
), 0))
1596 lhs_base
= get_base_address (lhs
);
1597 if (lhs_base
== NULL_TREE
1598 || (!DECL_P (lhs_base
) && TREE_CODE (lhs_base
) != MEM_REF
))
1601 then_rhs
= gimple_assign_rhs1 (then_assign
);
1602 else_rhs
= gimple_assign_rhs1 (else_assign
);
1603 then_locus
= gimple_location (then_assign
);
1604 else_locus
= gimple_location (else_assign
);
1606 /* Now we've checked the constraints, so do the transformation:
1607 1) Remove the stores. */
1608 gsi
= gsi_for_stmt (then_assign
);
1609 unlink_stmt_vdef (then_assign
);
1610 gsi_remove (&gsi
, true);
1611 release_defs (then_assign
);
1613 gsi
= gsi_for_stmt (else_assign
);
1614 unlink_stmt_vdef (else_assign
);
1615 gsi_remove (&gsi
, true);
1616 release_defs (else_assign
);
1618 /* 2) Create a PHI node at the join block, with one argument
1619 holding the old RHS, and the other holding the temporary
1620 where we stored the old memory contents. */
1621 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1622 newphi
= create_phi_node (name
, join_bb
);
1623 add_phi_arg (newphi
, then_rhs
, EDGE_SUCC (then_bb
, 0), then_locus
);
1624 add_phi_arg (newphi
, else_rhs
, EDGE_SUCC (else_bb
, 0), else_locus
);
1626 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1628 /* 3) Insert that PHI node. */
1629 gsi
= gsi_after_labels (join_bb
);
1630 if (gsi_end_p (gsi
))
1632 gsi
= gsi_last_bb (join_bb
);
1633 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1636 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1641 /* Conditional store replacement. We already know
1642 that the recognized pattern looks like so:
1645 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
1655 fallthrough (edge E0)
1659 We check that it is safe to sink the store to JOIN_BB by verifying that
1660 there are no read-after-write or write-after-write dependencies in
1661 THEN_BB and ELSE_BB. */
1664 cond_if_else_store_replacement (basic_block then_bb
, basic_block else_bb
,
1665 basic_block join_bb
)
1667 gimple then_assign
= last_and_only_stmt (then_bb
);
1668 gimple else_assign
= last_and_only_stmt (else_bb
);
1669 vec
<data_reference_p
> then_datarefs
, else_datarefs
;
1670 vec
<ddr_p
> then_ddrs
, else_ddrs
;
1671 gimple then_store
, else_store
;
1672 bool found
, ok
= false, res
;
1673 struct data_dependence_relation
*ddr
;
1674 data_reference_p then_dr
, else_dr
;
1676 tree then_lhs
, else_lhs
;
1677 vec
<gimple
> then_stores
, else_stores
;
1678 basic_block blocks
[3];
1680 if (MAX_STORES_TO_SINK
== 0)
1683 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
1684 if (then_assign
&& else_assign
)
1685 return cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1686 then_assign
, else_assign
);
1688 /* Find data references. */
1689 then_datarefs
.create (1);
1690 else_datarefs
.create (1);
1691 if ((find_data_references_in_bb (NULL
, then_bb
, &then_datarefs
)
1693 || !then_datarefs
.length ()
1694 || (find_data_references_in_bb (NULL
, else_bb
, &else_datarefs
)
1696 || !else_datarefs
.length ())
1698 free_data_refs (then_datarefs
);
1699 free_data_refs (else_datarefs
);
1703 /* Find pairs of stores with equal LHS. */
1704 then_stores
.create (1);
1705 else_stores
.create (1);
1706 FOR_EACH_VEC_ELT (then_datarefs
, i
, then_dr
)
1708 if (DR_IS_READ (then_dr
))
1711 then_store
= DR_STMT (then_dr
);
1712 then_lhs
= gimple_get_lhs (then_store
);
1715 FOR_EACH_VEC_ELT (else_datarefs
, j
, else_dr
)
1717 if (DR_IS_READ (else_dr
))
1720 else_store
= DR_STMT (else_dr
);
1721 else_lhs
= gimple_get_lhs (else_store
);
1723 if (operand_equal_p (then_lhs
, else_lhs
, 0))
1733 then_stores
.safe_push (then_store
);
1734 else_stores
.safe_push (else_store
);
1737 /* No pairs of stores found. */
1738 if (!then_stores
.length ()
1739 || then_stores
.length () > (unsigned) MAX_STORES_TO_SINK
)
1741 free_data_refs (then_datarefs
);
1742 free_data_refs (else_datarefs
);
1743 then_stores
.release ();
1744 else_stores
.release ();
1748 /* Compute and check data dependencies in both basic blocks. */
1749 then_ddrs
.create (1);
1750 else_ddrs
.create (1);
1751 if (!compute_all_dependences (then_datarefs
, &then_ddrs
,
1753 || !compute_all_dependences (else_datarefs
, &else_ddrs
,
1756 free_dependence_relations (then_ddrs
);
1757 free_dependence_relations (else_ddrs
);
1758 free_data_refs (then_datarefs
);
1759 free_data_refs (else_datarefs
);
1760 then_stores
.release ();
1761 else_stores
.release ();
1764 blocks
[0] = then_bb
;
1765 blocks
[1] = else_bb
;
1766 blocks
[2] = join_bb
;
1767 renumber_gimple_stmt_uids_in_blocks (blocks
, 3);
1769 /* Check that there are no read-after-write or write-after-write dependencies
1771 FOR_EACH_VEC_ELT (then_ddrs
, i
, ddr
)
1773 struct data_reference
*dra
= DDR_A (ddr
);
1774 struct data_reference
*drb
= DDR_B (ddr
);
1776 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1777 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1778 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1779 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1780 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1781 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1783 free_dependence_relations (then_ddrs
);
1784 free_dependence_relations (else_ddrs
);
1785 free_data_refs (then_datarefs
);
1786 free_data_refs (else_datarefs
);
1787 then_stores
.release ();
1788 else_stores
.release ();
1793 /* Check that there are no read-after-write or write-after-write dependencies
1795 FOR_EACH_VEC_ELT (else_ddrs
, i
, ddr
)
1797 struct data_reference
*dra
= DDR_A (ddr
);
1798 struct data_reference
*drb
= DDR_B (ddr
);
1800 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1801 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1802 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1803 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1804 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1805 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1807 free_dependence_relations (then_ddrs
);
1808 free_dependence_relations (else_ddrs
);
1809 free_data_refs (then_datarefs
);
1810 free_data_refs (else_datarefs
);
1811 then_stores
.release ();
1812 else_stores
.release ();
1817 /* Sink stores with same LHS. */
1818 FOR_EACH_VEC_ELT (then_stores
, i
, then_store
)
1820 else_store
= else_stores
[i
];
1821 res
= cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1822 then_store
, else_store
);
1826 free_dependence_relations (then_ddrs
);
1827 free_dependence_relations (else_ddrs
);
1828 free_data_refs (then_datarefs
);
1829 free_data_refs (else_datarefs
);
1830 then_stores
.release ();
1831 else_stores
.release ();
1836 /* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
1839 local_mem_dependence (gimple stmt
, basic_block bb
)
1841 tree vuse
= gimple_vuse (stmt
);
1847 def
= SSA_NAME_DEF_STMT (vuse
);
1848 return (def
&& gimple_bb (def
) == bb
);
1851 /* Given a "diamond" control-flow pattern where BB0 tests a condition,
1852 BB1 and BB2 are "then" and "else" blocks dependent on this test,
1853 and BB3 rejoins control flow following BB1 and BB2, look for
1854 opportunities to hoist loads as follows. If BB3 contains a PHI of
1855 two loads, one each occurring in BB1 and BB2, and the loads are
1856 provably of adjacent fields in the same structure, then move both
1857 loads into BB0. Of course this can only be done if there are no
1858 dependencies preventing such motion.
1860 One of the hoisted loads will always be speculative, so the
1861 transformation is currently conservative:
1863 - The fields must be strictly adjacent.
1864 - The two fields must occupy a single memory block that is
1865 guaranteed to not cross a page boundary.
1867 The last is difficult to prove, as such memory blocks should be
1868 aligned on the minimum of the stack alignment boundary and the
1869 alignment guaranteed by heap allocation interfaces. Thus we rely
1870 on a parameter for the alignment value.
1872 Provided a good value is used for the last case, the first
1873 restriction could possibly be relaxed. */
1876 hoist_adjacent_loads (basic_block bb0
, basic_block bb1
,
1877 basic_block bb2
, basic_block bb3
)
1879 int param_align
= PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
);
1880 unsigned param_align_bits
= (unsigned) (param_align
* BITS_PER_UNIT
);
1881 gimple_stmt_iterator gsi
;
1883 /* Walk the phis in bb3 looking for an opportunity. We are looking
1884 for phis of two SSA names, one each of which is defined in bb1 and
1886 for (gsi
= gsi_start_phis (bb3
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1888 gimple phi_stmt
= gsi_stmt (gsi
);
1889 gimple def1
, def2
, defswap
;
1890 tree arg1
, arg2
, ref1
, ref2
, field1
, field2
, fieldswap
;
1891 tree tree_offset1
, tree_offset2
, tree_size2
, next
;
1892 int offset1
, offset2
, size2
;
1894 gimple_stmt_iterator gsi2
;
1895 basic_block bb_for_def1
, bb_for_def2
;
1897 if (gimple_phi_num_args (phi_stmt
) != 2
1898 || virtual_operand_p (gimple_phi_result (phi_stmt
)))
1901 arg1
= gimple_phi_arg_def (phi_stmt
, 0);
1902 arg2
= gimple_phi_arg_def (phi_stmt
, 1);
1904 if (TREE_CODE (arg1
) != SSA_NAME
1905 || TREE_CODE (arg2
) != SSA_NAME
1906 || SSA_NAME_IS_DEFAULT_DEF (arg1
)
1907 || SSA_NAME_IS_DEFAULT_DEF (arg2
))
1910 def1
= SSA_NAME_DEF_STMT (arg1
);
1911 def2
= SSA_NAME_DEF_STMT (arg2
);
1913 if ((gimple_bb (def1
) != bb1
|| gimple_bb (def2
) != bb2
)
1914 && (gimple_bb (def2
) != bb1
|| gimple_bb (def1
) != bb2
))
1917 /* Check the mode of the arguments to be sure a conditional move
1918 can be generated for it. */
1919 if (optab_handler (movcc_optab
, TYPE_MODE (TREE_TYPE (arg1
)))
1920 == CODE_FOR_nothing
)
1923 /* Both statements must be assignments whose RHS is a COMPONENT_REF. */
1924 if (!gimple_assign_single_p (def1
)
1925 || !gimple_assign_single_p (def2
)
1926 || gimple_has_volatile_ops (def1
)
1927 || gimple_has_volatile_ops (def2
))
1930 ref1
= gimple_assign_rhs1 (def1
);
1931 ref2
= gimple_assign_rhs1 (def2
);
1933 if (TREE_CODE (ref1
) != COMPONENT_REF
1934 || TREE_CODE (ref2
) != COMPONENT_REF
)
1937 /* The zeroth operand of the two component references must be
1938 identical. It is not sufficient to compare get_base_address of
1939 the two references, because this could allow for different
1940 elements of the same array in the two trees. It is not safe to
1941 assume that the existence of one array element implies the
1942 existence of a different one. */
1943 if (!operand_equal_p (TREE_OPERAND (ref1
, 0), TREE_OPERAND (ref2
, 0), 0))
1946 field1
= TREE_OPERAND (ref1
, 1);
1947 field2
= TREE_OPERAND (ref2
, 1);
1949 /* Check for field adjacency, and ensure field1 comes first. */
1950 for (next
= DECL_CHAIN (field1
);
1951 next
&& TREE_CODE (next
) != FIELD_DECL
;
1952 next
= DECL_CHAIN (next
))
1957 for (next
= DECL_CHAIN (field2
);
1958 next
&& TREE_CODE (next
) != FIELD_DECL
;
1959 next
= DECL_CHAIN (next
))
1973 bb_for_def1
= gimple_bb (def1
);
1974 bb_for_def2
= gimple_bb (def2
);
1976 /* Check for proper alignment of the first field. */
1977 tree_offset1
= bit_position (field1
);
1978 tree_offset2
= bit_position (field2
);
1979 tree_size2
= DECL_SIZE (field2
);
1981 if (!host_integerp (tree_offset1
, 1)
1982 || !host_integerp (tree_offset2
, 1)
1983 || !host_integerp (tree_size2
, 1))
1986 offset1
= TREE_INT_CST_LOW (tree_offset1
);
1987 offset2
= TREE_INT_CST_LOW (tree_offset2
);
1988 size2
= TREE_INT_CST_LOW (tree_size2
);
1989 align1
= DECL_ALIGN (field1
) % param_align_bits
;
1991 if (offset1
% BITS_PER_UNIT
!= 0)
1994 /* For profitability, the two field references should fit within
1995 a single cache line. */
1996 if (align1
+ offset2
- offset1
+ size2
> param_align_bits
)
1999 /* The two expressions cannot be dependent upon vdefs defined
2001 if (local_mem_dependence (def1
, bb_for_def1
)
2002 || local_mem_dependence (def2
, bb_for_def2
))
2005 /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
2006 bb0. We hoist the first one first so that a cache miss is handled
2007 efficiently regardless of hardware cache-fill policy. */
2008 gsi2
= gsi_for_stmt (def1
);
2009 gsi_move_to_bb_end (&gsi2
, bb0
);
2010 gsi2
= gsi_for_stmt (def2
);
2011 gsi_move_to_bb_end (&gsi2
, bb0
);
2013 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2016 "\nHoisting adjacent loads from %d and %d into %d: \n",
2017 bb_for_def1
->index
, bb_for_def2
->index
, bb0
->index
);
2018 print_gimple_stmt (dump_file
, def1
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2019 print_gimple_stmt (dump_file
, def2
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2024 /* Determine whether we should attempt to hoist adjacent loads out of
2025 diamond patterns in pass_phiopt. Always hoist loads if
2026 -fhoist-adjacent-loads is specified and the target machine has
2027 both a conditional move instruction and a defined cache line size. */
2030 gate_hoist_loads (void)
2032 return (flag_hoist_adjacent_loads
== 1
2033 && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
)
2034 && HAVE_conditional_move
);
2037 /* Always do these optimizations if we have SSA
2038 trees to work on. */
2047 const pass_data pass_data_phiopt
=
2049 GIMPLE_PASS
, /* type */
2050 "phiopt", /* name */
2051 OPTGROUP_NONE
, /* optinfo_flags */
2052 true, /* has_gate */
2053 true, /* has_execute */
2054 TV_TREE_PHIOPT
, /* tv_id */
2055 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2056 0, /* properties_provided */
2057 0, /* properties_destroyed */
2058 0, /* todo_flags_start */
2059 ( TODO_verify_ssa
| TODO_verify_flow
2060 | TODO_verify_stmts
), /* todo_flags_finish */
2063 class pass_phiopt
: public gimple_opt_pass
2066 pass_phiopt (gcc::context
*ctxt
)
2067 : gimple_opt_pass (pass_data_phiopt
, ctxt
)
2070 /* opt_pass methods: */
2071 opt_pass
* clone () { return new pass_phiopt (m_ctxt
); }
2072 bool gate () { return gate_phiopt (); }
2073 unsigned int execute () { return tree_ssa_phiopt (); }
2075 }; // class pass_phiopt
2080 make_pass_phiopt (gcc::context
*ctxt
)
2082 return new pass_phiopt (ctxt
);
2088 return flag_tree_cselim
;
2093 const pass_data pass_data_cselim
=
2095 GIMPLE_PASS
, /* type */
2096 "cselim", /* name */
2097 OPTGROUP_NONE
, /* optinfo_flags */
2098 true, /* has_gate */
2099 true, /* has_execute */
2100 TV_TREE_PHIOPT
, /* tv_id */
2101 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2102 0, /* properties_provided */
2103 0, /* properties_destroyed */
2104 0, /* todo_flags_start */
2105 ( TODO_verify_ssa
| TODO_verify_flow
2106 | TODO_verify_stmts
), /* todo_flags_finish */
2109 class pass_cselim
: public gimple_opt_pass
2112 pass_cselim (gcc::context
*ctxt
)
2113 : gimple_opt_pass (pass_data_cselim
, ctxt
)
2116 /* opt_pass methods: */
2117 bool gate () { return gate_cselim (); }
2118 unsigned int execute () { return tree_ssa_cs_elim (); }
2120 }; // class pass_cselim
2125 make_pass_cselim (gcc::context
*ctxt
)
2127 return new pass_cselim (ctxt
);