1 /* Optimization of PHI nodes by converting them into straightline code.
2 Copyright (C) 2004-2014 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"
26 #include "stor-layout.h"
34 #include "hard-reg-set.h"
37 #include "dominance.h"
40 #include "basic-block.h"
41 #include "tree-ssa-alias.h"
42 #include "internal-fn.h"
43 #include "gimple-expr.h"
47 #include "gimple-iterator.h"
48 #include "gimplify-me.h"
49 #include "gimple-ssa.h"
51 #include "tree-phinodes.h"
52 #include "ssa-iterators.h"
53 #include "stringpool.h"
54 #include "tree-ssanames.h"
57 #include "tree-pass.h"
58 #include "langhooks.h"
61 #include "tree-data-ref.h"
62 #include "gimple-pretty-print.h"
63 #include "insn-config.h"
66 #include "tree-scalar-evolution.h"
67 #include "tree-inline.h"
69 #ifndef HAVE_conditional_move
70 #define HAVE_conditional_move (0)
73 static unsigned int tree_ssa_phiopt_worker (bool, bool);
74 static bool conditional_replacement (basic_block
, basic_block
,
75 edge
, edge
, gimple
, tree
, tree
);
76 static int value_replacement (basic_block
, basic_block
,
77 edge
, edge
, gimple
, tree
, tree
);
78 static bool minmax_replacement (basic_block
, basic_block
,
79 edge
, edge
, gimple
, tree
, tree
);
80 static bool abs_replacement (basic_block
, basic_block
,
81 edge
, edge
, gimple
, tree
, tree
);
82 static bool neg_replacement (basic_block
, basic_block
,
83 edge
, edge
, gimple
, tree
, tree
);
84 static bool cond_store_replacement (basic_block
, basic_block
, edge
, edge
,
86 static bool cond_if_else_store_replacement (basic_block
, basic_block
, basic_block
);
87 static hash_set
<tree
> * get_non_trapping ();
88 static void replace_phi_edge_with_variable (basic_block
, edge
, gimple
, tree
);
89 static void hoist_adjacent_loads (basic_block
, basic_block
,
90 basic_block
, basic_block
);
91 static bool gate_hoist_loads (void);
93 /* This pass tries to transform conditional stores into unconditional
94 ones, enabling further simplifications with the simpler then and else
95 blocks. In particular it replaces this:
98 if (cond) goto bb2; else goto bb1;
106 if (cond) goto bb1; else goto bb2;
110 condtmp = PHI <RHS, condtmp'>
113 This transformation can only be done under several constraints,
114 documented below. It also replaces:
117 if (cond) goto bb2; else goto bb1;
128 if (cond) goto bb3; else goto bb1;
131 condtmp = PHI <RHS1, RHS2>
135 tree_ssa_cs_elim (void)
138 /* ??? We are not interested in loop related info, but the following
139 will create it, ICEing as we didn't init loops with pre-headers.
140 An interfacing issue of find_data_references_in_bb. */
141 loop_optimizer_init (LOOPS_NORMAL
);
143 todo
= tree_ssa_phiopt_worker (true, false);
145 loop_optimizer_finalize ();
149 /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
152 single_non_singleton_phi_for_edges (gimple_seq seq
, edge e0
, edge e1
)
154 gimple_stmt_iterator i
;
156 if (gimple_seq_singleton_p (seq
))
157 return gsi_stmt (gsi_start (seq
));
158 for (i
= gsi_start (seq
); !gsi_end_p (i
); gsi_next (&i
))
160 gimple p
= gsi_stmt (i
);
161 /* If the PHI arguments are equal then we can skip this PHI. */
162 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p
, e0
->dest_idx
),
163 gimple_phi_arg_def (p
, e1
->dest_idx
)))
166 /* If we already have a PHI that has the two edge arguments are
167 different, then return it is not a singleton for these PHIs. */
176 /* The core routine of conditional store replacement and normal
177 phi optimizations. Both share much of the infrastructure in how
178 to match applicable basic block patterns. DO_STORE_ELIM is true
179 when we want to do conditional store replacement, false otherwise.
180 DO_HOIST_LOADS is true when we want to hoist adjacent loads out
181 of diamond control flow patterns, false otherwise. */
183 tree_ssa_phiopt_worker (bool do_store_elim
, bool do_hoist_loads
)
186 basic_block
*bb_order
;
188 bool cfgchanged
= false;
189 hash_set
<tree
> *nontrap
= 0;
192 /* Calculate the set of non-trapping memory accesses. */
193 nontrap
= get_non_trapping ();
195 /* The replacement of conditional negation with a non-branching
196 sequence is really only a win when optimizing for speed and we
197 can avoid transformations by gimple if-conversion that result
198 in poor RTL generation.
200 Ideally either gimple if-conversion or the RTL expanders will
201 be improved and the code to emit branchless conditional negation
203 bool replace_conditional_negation
= false;
205 replace_conditional_negation
206 = ((!optimize_size
&& optimize
>= 2)
207 || (((flag_tree_loop_vectorize
|| cfun
->has_force_vectorize_loops
)
208 && flag_tree_loop_if_convert
!= 0)
209 || flag_tree_loop_if_convert
== 1
210 || flag_tree_loop_if_convert_stores
== 1));
212 /* Search every basic block for COND_EXPR we may be able to optimize.
214 We walk the blocks in order that guarantees that a block with
215 a single predecessor is processed before the predecessor.
216 This ensures that we collapse inner ifs before visiting the
217 outer ones, and also that we do not try to visit a removed
219 bb_order
= single_pred_before_succ_order ();
220 n
= n_basic_blocks_for_fn (cfun
) - NUM_FIXED_BLOCKS
;
222 for (i
= 0; i
< n
; i
++)
224 gimple cond_stmt
, phi
;
225 basic_block bb1
, bb2
;
231 cond_stmt
= last_stmt (bb
);
232 /* Check to see if the last statement is a GIMPLE_COND. */
234 || gimple_code (cond_stmt
) != GIMPLE_COND
)
237 e1
= EDGE_SUCC (bb
, 0);
239 e2
= EDGE_SUCC (bb
, 1);
242 /* We cannot do the optimization on abnormal edges. */
243 if ((e1
->flags
& EDGE_ABNORMAL
) != 0
244 || (e2
->flags
& EDGE_ABNORMAL
) != 0)
247 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
248 if (EDGE_COUNT (bb1
->succs
) == 0
250 || EDGE_COUNT (bb2
->succs
) == 0)
253 /* Find the bb which is the fall through to the other. */
254 if (EDGE_SUCC (bb1
, 0)->dest
== bb2
)
256 else if (EDGE_SUCC (bb2
, 0)->dest
== bb1
)
258 basic_block bb_tmp
= bb1
;
265 else if (do_store_elim
266 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
268 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
270 if (!single_succ_p (bb1
)
271 || (EDGE_SUCC (bb1
, 0)->flags
& EDGE_FALLTHRU
) == 0
272 || !single_succ_p (bb2
)
273 || (EDGE_SUCC (bb2
, 0)->flags
& EDGE_FALLTHRU
) == 0
274 || EDGE_COUNT (bb3
->preds
) != 2)
276 if (cond_if_else_store_replacement (bb1
, bb2
, bb3
))
280 else if (do_hoist_loads
281 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
283 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
285 if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt
)))
286 && single_succ_p (bb1
)
287 && single_succ_p (bb2
)
288 && single_pred_p (bb1
)
289 && single_pred_p (bb2
)
290 && EDGE_COUNT (bb
->succs
) == 2
291 && EDGE_COUNT (bb3
->preds
) == 2
292 /* If one edge or the other is dominant, a conditional move
293 is likely to perform worse than the well-predicted branch. */
294 && !predictable_edge_p (EDGE_SUCC (bb
, 0))
295 && !predictable_edge_p (EDGE_SUCC (bb
, 1)))
296 hoist_adjacent_loads (bb
, bb1
, bb2
, bb3
);
302 e1
= EDGE_SUCC (bb1
, 0);
304 /* Make sure that bb1 is just a fall through. */
305 if (!single_succ_p (bb1
)
306 || (e1
->flags
& EDGE_FALLTHRU
) == 0)
309 /* Also make sure that bb1 only have one predecessor and that it
311 if (!single_pred_p (bb1
)
312 || single_pred (bb1
) != bb
)
317 /* bb1 is the middle block, bb2 the join block, bb the split block,
318 e1 the fallthrough edge from bb1 to bb2. We can't do the
319 optimization if the join block has more than two predecessors. */
320 if (EDGE_COUNT (bb2
->preds
) > 2)
322 if (cond_store_replacement (bb1
, bb2
, e1
, e2
, nontrap
))
327 gimple_seq phis
= phi_nodes (bb2
);
328 gimple_stmt_iterator gsi
;
329 bool candorest
= true;
331 /* Value replacement can work with more than one PHI
332 so try that first. */
333 for (gsi
= gsi_start (phis
); !gsi_end_p (gsi
); gsi_next (&gsi
))
335 phi
= gsi_stmt (gsi
);
336 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
337 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
338 if (value_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
) == 2)
349 phi
= single_non_singleton_phi_for_edges (phis
, e1
, e2
);
353 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
354 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
356 /* Something is wrong if we cannot find the arguments in the PHI
358 gcc_assert (arg0
!= NULL
&& arg1
!= NULL
);
360 /* Do the replacement of conditional if it can be done. */
361 if (conditional_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
363 else if (abs_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
365 else if (replace_conditional_negation
366 && neg_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
368 else if (minmax_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
377 /* If the CFG has changed, we should cleanup the CFG. */
378 if (cfgchanged
&& do_store_elim
)
380 /* In cond-store replacement we have added some loads on edges
381 and new VOPS (as we moved the store, and created a load). */
382 gsi_commit_edge_inserts ();
383 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
386 return TODO_cleanup_cfg
;
390 /* Replace PHI node element whose edge is E in block BB with variable NEW.
391 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
392 is known to have two edges, one of which must reach BB). */
395 replace_phi_edge_with_variable (basic_block cond_block
,
396 edge e
, gimple phi
, tree new_tree
)
398 basic_block bb
= gimple_bb (phi
);
399 basic_block block_to_remove
;
400 gimple_stmt_iterator gsi
;
402 /* Change the PHI argument to new. */
403 SET_USE (PHI_ARG_DEF_PTR (phi
, e
->dest_idx
), new_tree
);
405 /* Remove the empty basic block. */
406 if (EDGE_SUCC (cond_block
, 0)->dest
== bb
)
408 EDGE_SUCC (cond_block
, 0)->flags
|= EDGE_FALLTHRU
;
409 EDGE_SUCC (cond_block
, 0)->flags
&= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
410 EDGE_SUCC (cond_block
, 0)->probability
= REG_BR_PROB_BASE
;
411 EDGE_SUCC (cond_block
, 0)->count
+= EDGE_SUCC (cond_block
, 1)->count
;
413 block_to_remove
= EDGE_SUCC (cond_block
, 1)->dest
;
417 EDGE_SUCC (cond_block
, 1)->flags
|= EDGE_FALLTHRU
;
418 EDGE_SUCC (cond_block
, 1)->flags
419 &= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
420 EDGE_SUCC (cond_block
, 1)->probability
= REG_BR_PROB_BASE
;
421 EDGE_SUCC (cond_block
, 1)->count
+= EDGE_SUCC (cond_block
, 0)->count
;
423 block_to_remove
= EDGE_SUCC (cond_block
, 0)->dest
;
425 delete_basic_block (block_to_remove
);
427 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
428 gsi
= gsi_last_bb (cond_block
);
429 gsi_remove (&gsi
, true);
431 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
433 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
438 /* The function conditional_replacement does the main work of doing the
439 conditional replacement. Return true if the replacement is done.
440 Otherwise return false.
441 BB is the basic block where the replacement is going to be done on. ARG0
442 is argument 0 from PHI. Likewise for ARG1. */
445 conditional_replacement (basic_block cond_bb
, basic_block middle_bb
,
446 edge e0
, edge e1
, gimple phi
,
447 tree arg0
, tree arg1
)
450 gimple stmt
, new_stmt
;
452 gimple_stmt_iterator gsi
;
453 edge true_edge
, false_edge
;
454 tree new_var
, new_var2
;
457 /* FIXME: Gimplification of complex type is too hard for now. */
458 /* We aren't prepared to handle vectors either (and it is a question
459 if it would be worthwhile anyway). */
460 if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
461 || POINTER_TYPE_P (TREE_TYPE (arg0
)))
462 || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1
))
463 || POINTER_TYPE_P (TREE_TYPE (arg1
))))
466 /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
467 convert it to the conditional. */
468 if ((integer_zerop (arg0
) && integer_onep (arg1
))
469 || (integer_zerop (arg1
) && integer_onep (arg0
)))
471 else if ((integer_zerop (arg0
) && integer_all_onesp (arg1
))
472 || (integer_zerop (arg1
) && integer_all_onesp (arg0
)))
477 if (!empty_block_p (middle_bb
))
480 /* At this point we know we have a GIMPLE_COND with two successors.
481 One successor is BB, the other successor is an empty block which
482 falls through into BB.
484 There is a single PHI node at the join point (BB) and its arguments
485 are constants (0, 1) or (0, -1).
487 So, given the condition COND, and the two PHI arguments, we can
488 rewrite this PHI into non-branching code:
490 dest = (COND) or dest = COND'
492 We use the condition as-is if the argument associated with the
493 true edge has the value one or the argument associated with the
494 false edge as the value zero. Note that those conditions are not
495 the same since only one of the outgoing edges from the GIMPLE_COND
496 will directly reach BB and thus be associated with an argument. */
498 stmt
= last_stmt (cond_bb
);
499 result
= PHI_RESULT (phi
);
501 /* To handle special cases like floating point comparison, it is easier and
502 less error-prone to build a tree and gimplify it on the fly though it is
504 cond
= fold_build2_loc (gimple_location (stmt
),
505 gimple_cond_code (stmt
), boolean_type_node
,
506 gimple_cond_lhs (stmt
), gimple_cond_rhs (stmt
));
508 /* We need to know which is the true edge and which is the false
509 edge so that we know when to invert the condition below. */
510 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
511 if ((e0
== true_edge
&& integer_zerop (arg0
))
512 || (e0
== false_edge
&& !integer_zerop (arg0
))
513 || (e1
== true_edge
&& integer_zerop (arg1
))
514 || (e1
== false_edge
&& !integer_zerop (arg1
)))
515 cond
= fold_build1_loc (gimple_location (stmt
),
516 TRUTH_NOT_EXPR
, TREE_TYPE (cond
), cond
);
520 cond
= fold_convert_loc (gimple_location (stmt
),
521 TREE_TYPE (result
), cond
);
522 cond
= fold_build1_loc (gimple_location (stmt
),
523 NEGATE_EXPR
, TREE_TYPE (cond
), cond
);
526 /* Insert our new statements at the end of conditional block before the
528 gsi
= gsi_for_stmt (stmt
);
529 new_var
= force_gimple_operand_gsi (&gsi
, cond
, true, NULL
, true,
532 if (!useless_type_conversion_p (TREE_TYPE (result
), TREE_TYPE (new_var
)))
534 source_location locus_0
, locus_1
;
536 new_var2
= make_ssa_name (TREE_TYPE (result
), NULL
);
537 new_stmt
= gimple_build_assign_with_ops (CONVERT_EXPR
, new_var2
,
539 gsi_insert_before (&gsi
, new_stmt
, GSI_SAME_STMT
);
542 /* Set the locus to the first argument, unless is doesn't have one. */
543 locus_0
= gimple_phi_arg_location (phi
, 0);
544 locus_1
= gimple_phi_arg_location (phi
, 1);
545 if (locus_0
== UNKNOWN_LOCATION
)
547 gimple_set_location (new_stmt
, locus_0
);
550 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_var
);
552 /* Note that we optimized this PHI. */
556 /* Update *ARG which is defined in STMT so that it contains the
557 computed value if that seems profitable. Return true if the
558 statement is made dead by that rewriting. */
561 jump_function_from_stmt (tree
*arg
, gimple stmt
)
563 enum tree_code code
= gimple_assign_rhs_code (stmt
);
564 if (code
== ADDR_EXPR
)
566 /* For arg = &p->i transform it to p, if possible. */
567 tree rhs1
= gimple_assign_rhs1 (stmt
);
568 HOST_WIDE_INT offset
;
569 tree tem
= get_addr_base_and_unit_offset (TREE_OPERAND (rhs1
, 0),
572 && TREE_CODE (tem
) == MEM_REF
573 && (mem_ref_offset (tem
) + offset
) == 0)
575 *arg
= TREE_OPERAND (tem
, 0);
579 /* TODO: Much like IPA-CP jump-functions we want to handle constant
580 additions symbolically here, and we'd need to update the comparison
581 code that compares the arg + cst tuples in our caller. For now the
582 code above exactly handles the VEC_BASE pattern from vec.h. */
586 /* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
587 of the form SSA_NAME NE 0.
589 If RHS is fed by a simple EQ_EXPR comparison of two values, see if
590 the two input values of the EQ_EXPR match arg0 and arg1.
592 If so update *code and return TRUE. Otherwise return FALSE. */
595 rhs_is_fed_for_value_replacement (const_tree arg0
, const_tree arg1
,
596 enum tree_code
*code
, const_tree rhs
)
598 /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
600 if (TREE_CODE (rhs
) == SSA_NAME
)
602 gimple def1
= SSA_NAME_DEF_STMT (rhs
);
604 /* Verify the defining statement has an EQ_EXPR on the RHS. */
605 if (is_gimple_assign (def1
) && gimple_assign_rhs_code (def1
) == EQ_EXPR
)
607 /* Finally verify the source operands of the EQ_EXPR are equal
609 tree op0
= gimple_assign_rhs1 (def1
);
610 tree op1
= gimple_assign_rhs2 (def1
);
611 if ((operand_equal_for_phi_arg_p (arg0
, op0
)
612 && operand_equal_for_phi_arg_p (arg1
, op1
))
613 || (operand_equal_for_phi_arg_p (arg0
, op1
)
614 && operand_equal_for_phi_arg_p (arg1
, op0
)))
616 /* We will perform the optimization. */
617 *code
= gimple_assign_rhs_code (def1
);
625 /* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
627 Also return TRUE if arg0/arg1 are equal to the source arguments of a
628 an EQ comparison feeding a BIT_AND_EXPR which feeds COND.
630 Return FALSE otherwise. */
633 operand_equal_for_value_replacement (const_tree arg0
, const_tree arg1
,
634 enum tree_code
*code
, gimple cond
)
637 tree lhs
= gimple_cond_lhs (cond
);
638 tree rhs
= gimple_cond_rhs (cond
);
640 if ((operand_equal_for_phi_arg_p (arg0
, lhs
)
641 && operand_equal_for_phi_arg_p (arg1
, rhs
))
642 || (operand_equal_for_phi_arg_p (arg1
, lhs
)
643 && operand_equal_for_phi_arg_p (arg0
, rhs
)))
646 /* Now handle more complex case where we have an EQ comparison
647 which feeds a BIT_AND_EXPR which feeds COND.
649 First verify that COND is of the form SSA_NAME NE 0. */
650 if (*code
!= NE_EXPR
|| !integer_zerop (rhs
)
651 || TREE_CODE (lhs
) != SSA_NAME
)
654 /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */
655 def
= SSA_NAME_DEF_STMT (lhs
);
656 if (!is_gimple_assign (def
) || gimple_assign_rhs_code (def
) != BIT_AND_EXPR
)
659 /* Now verify arg0/arg1 correspond to the source arguments of an
660 EQ comparison feeding the BIT_AND_EXPR. */
662 tree tmp
= gimple_assign_rhs1 (def
);
663 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
666 tmp
= gimple_assign_rhs2 (def
);
667 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
673 /* Returns true if ARG is a neutral element for operation CODE
674 on the RIGHT side. */
677 neutral_element_p (tree_code code
, tree arg
, bool right
)
684 return integer_zerop (arg
);
691 case POINTER_PLUS_EXPR
:
692 return right
&& integer_zerop (arg
);
695 return integer_onep (arg
);
702 return right
&& integer_onep (arg
);
705 return integer_all_onesp (arg
);
712 /* Returns true if ARG is an absorbing element for operation CODE. */
715 absorbing_element_p (tree_code code
, tree arg
)
720 return integer_all_onesp (arg
);
724 return integer_zerop (arg
);
731 /* The function value_replacement does the main work of doing the value
732 replacement. Return non-zero if the replacement is done. Otherwise return
733 0. If we remove the middle basic block, return 2.
734 BB is the basic block where the replacement is going to be done on. ARG0
735 is argument 0 from the PHI. Likewise for ARG1. */
738 value_replacement (basic_block cond_bb
, basic_block middle_bb
,
739 edge e0
, edge e1
, gimple phi
,
740 tree arg0
, tree arg1
)
742 gimple_stmt_iterator gsi
;
744 edge true_edge
, false_edge
;
746 bool emtpy_or_with_defined_p
= true;
748 /* If the type says honor signed zeros we cannot do this
750 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
753 /* If there is a statement in MIDDLE_BB that defines one of the PHI
754 arguments, then adjust arg0 or arg1. */
755 gsi
= gsi_start_nondebug_after_labels_bb (middle_bb
);
756 while (!gsi_end_p (gsi
))
758 gimple stmt
= gsi_stmt (gsi
);
760 gsi_next_nondebug (&gsi
);
761 if (!is_gimple_assign (stmt
))
763 emtpy_or_with_defined_p
= false;
766 /* Now try to adjust arg0 or arg1 according to the computation
768 lhs
= gimple_assign_lhs (stmt
);
770 && jump_function_from_stmt (&arg0
, stmt
))
772 && jump_function_from_stmt (&arg1
, stmt
)))
773 emtpy_or_with_defined_p
= false;
776 cond
= last_stmt (cond_bb
);
777 code
= gimple_cond_code (cond
);
779 /* This transformation is only valid for equality comparisons. */
780 if (code
!= NE_EXPR
&& code
!= EQ_EXPR
)
783 /* We need to know which is the true edge and which is the false
784 edge so that we know if have abs or negative abs. */
785 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
787 /* At this point we know we have a COND_EXPR with two successors.
788 One successor is BB, the other successor is an empty block which
789 falls through into BB.
791 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
793 There is a single PHI node at the join point (BB) with two arguments.
795 We now need to verify that the two arguments in the PHI node match
796 the two arguments to the equality comparison. */
798 if (operand_equal_for_value_replacement (arg0
, arg1
, &code
, cond
))
803 /* For NE_EXPR, we want to build an assignment result = arg where
804 arg is the PHI argument associated with the true edge. For
805 EQ_EXPR we want the PHI argument associated with the false edge. */
806 e
= (code
== NE_EXPR
? true_edge
: false_edge
);
808 /* Unfortunately, E may not reach BB (it may instead have gone to
809 OTHER_BLOCK). If that is the case, then we want the single outgoing
810 edge from OTHER_BLOCK which reaches BB and represents the desired
811 path from COND_BLOCK. */
812 if (e
->dest
== middle_bb
)
813 e
= single_succ_edge (e
->dest
);
815 /* Now we know the incoming edge to BB that has the argument for the
816 RHS of our new assignment statement. */
822 /* If the middle basic block was empty or is defining the
823 PHI arguments and this is a single phi where the args are different
824 for the edges e0 and e1 then we can remove the middle basic block. */
825 if (emtpy_or_with_defined_p
826 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)),
829 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, arg
);
830 /* Note that we optimized this PHI. */
835 /* Replace the PHI arguments with arg. */
836 SET_PHI_ARG_DEF (phi
, e0
->dest_idx
, arg
);
837 SET_PHI_ARG_DEF (phi
, e1
->dest_idx
, arg
);
838 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
840 fprintf (dump_file
, "PHI ");
841 print_generic_expr (dump_file
, gimple_phi_result (phi
), 0);
842 fprintf (dump_file
, " reduced for COND_EXPR in block %d to ",
844 print_generic_expr (dump_file
, arg
, 0);
845 fprintf (dump_file
, ".\n");
852 /* Now optimize (x != 0) ? x + y : y to just y.
853 The following condition is too restrictive, there can easily be another
854 stmt in middle_bb, for instance a CONVERT_EXPR for the second argument. */
855 gimple assign
= last_and_only_stmt (middle_bb
);
856 if (!assign
|| gimple_code (assign
) != GIMPLE_ASSIGN
857 || gimple_assign_rhs_class (assign
) != GIMPLE_BINARY_RHS
858 || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
859 && !POINTER_TYPE_P (TREE_TYPE (arg0
))))
862 /* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */
863 if (!gimple_seq_empty_p (phi_nodes (middle_bb
)))
866 /* Only transform if it removes the condition. */
867 if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)), e0
, e1
))
870 /* Size-wise, this is always profitable. */
871 if (optimize_bb_for_speed_p (cond_bb
)
872 /* The special case is useless if it has a low probability. */
873 && profile_status_for_fn (cfun
) != PROFILE_ABSENT
874 && EDGE_PRED (middle_bb
, 0)->probability
< PROB_EVEN
875 /* If assign is cheap, there is no point avoiding it. */
876 && estimate_num_insns (assign
, &eni_time_weights
)
877 >= 3 * estimate_num_insns (cond
, &eni_time_weights
))
880 tree lhs
= gimple_assign_lhs (assign
);
881 tree rhs1
= gimple_assign_rhs1 (assign
);
882 tree rhs2
= gimple_assign_rhs2 (assign
);
883 enum tree_code code_def
= gimple_assign_rhs_code (assign
);
884 tree cond_lhs
= gimple_cond_lhs (cond
);
885 tree cond_rhs
= gimple_cond_rhs (cond
);
887 if (((code
== NE_EXPR
&& e1
== false_edge
)
888 || (code
== EQ_EXPR
&& e1
== true_edge
))
891 && operand_equal_for_phi_arg_p (rhs2
, cond_lhs
)
892 && neutral_element_p (code_def
, cond_rhs
, true))
894 && operand_equal_for_phi_arg_p (rhs1
, cond_lhs
)
895 && neutral_element_p (code_def
, cond_rhs
, false))
896 || (operand_equal_for_phi_arg_p (arg1
, cond_rhs
)
897 && (operand_equal_for_phi_arg_p (rhs2
, cond_lhs
)
898 || operand_equal_for_phi_arg_p (rhs1
, cond_lhs
))
899 && absorbing_element_p (code_def
, cond_rhs
))))
901 gsi
= gsi_for_stmt (cond
);
902 gimple_stmt_iterator gsi_from
= gsi_for_stmt (assign
);
903 gsi_move_before (&gsi_from
, &gsi
);
904 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, lhs
);
911 /* The function minmax_replacement does the main work of doing the minmax
912 replacement. Return true if the replacement is done. Otherwise return
914 BB is the basic block where the replacement is going to be done on. ARG0
915 is argument 0 from the PHI. Likewise for ARG1. */
918 minmax_replacement (basic_block cond_bb
, basic_block middle_bb
,
919 edge e0
, edge e1
, gimple phi
,
920 tree arg0
, tree arg1
)
923 gimple cond
, new_stmt
;
924 edge true_edge
, false_edge
;
925 enum tree_code cmp
, minmax
, ass_code
;
926 tree smaller
, larger
, arg_true
, arg_false
;
927 gimple_stmt_iterator gsi
, gsi_from
;
929 type
= TREE_TYPE (PHI_RESULT (phi
));
931 /* The optimization may be unsafe due to NaNs. */
932 if (HONOR_NANS (TYPE_MODE (type
)))
935 cond
= last_stmt (cond_bb
);
936 cmp
= gimple_cond_code (cond
);
938 /* This transformation is only valid for order comparisons. Record which
939 operand is smaller/larger if the result of the comparison is true. */
940 if (cmp
== LT_EXPR
|| cmp
== LE_EXPR
)
942 smaller
= gimple_cond_lhs (cond
);
943 larger
= gimple_cond_rhs (cond
);
945 else if (cmp
== GT_EXPR
|| cmp
== GE_EXPR
)
947 smaller
= gimple_cond_rhs (cond
);
948 larger
= gimple_cond_lhs (cond
);
953 /* We need to know which is the true edge and which is the false
954 edge so that we know if have abs or negative abs. */
955 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
957 /* Forward the edges over the middle basic block. */
958 if (true_edge
->dest
== middle_bb
)
959 true_edge
= EDGE_SUCC (true_edge
->dest
, 0);
960 if (false_edge
->dest
== middle_bb
)
961 false_edge
= EDGE_SUCC (false_edge
->dest
, 0);
965 gcc_assert (false_edge
== e1
);
971 gcc_assert (false_edge
== e0
);
972 gcc_assert (true_edge
== e1
);
977 if (empty_block_p (middle_bb
))
979 if (operand_equal_for_phi_arg_p (arg_true
, smaller
)
980 && operand_equal_for_phi_arg_p (arg_false
, larger
))
984 if (smaller < larger)
990 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
)
991 && operand_equal_for_phi_arg_p (arg_true
, larger
))
998 /* Recognize the following case, assuming d <= u:
1004 This is equivalent to
1009 gimple assign
= last_and_only_stmt (middle_bb
);
1010 tree lhs
, op0
, op1
, bound
;
1013 || gimple_code (assign
) != GIMPLE_ASSIGN
)
1016 lhs
= gimple_assign_lhs (assign
);
1017 ass_code
= gimple_assign_rhs_code (assign
);
1018 if (ass_code
!= MAX_EXPR
&& ass_code
!= MIN_EXPR
)
1020 op0
= gimple_assign_rhs1 (assign
);
1021 op1
= gimple_assign_rhs2 (assign
);
1023 if (true_edge
->src
== middle_bb
)
1025 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
1026 if (!operand_equal_for_phi_arg_p (lhs
, arg_true
))
1029 if (operand_equal_for_phi_arg_p (arg_false
, larger
))
1033 if (smaller < larger)
1035 r' = MAX_EXPR (smaller, bound)
1037 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
1038 if (ass_code
!= MAX_EXPR
)
1042 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1044 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1049 /* We need BOUND <= LARGER. */
1050 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1054 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
))
1058 if (smaller < larger)
1060 r' = MIN_EXPR (larger, bound)
1062 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
1063 if (ass_code
!= MIN_EXPR
)
1067 if (operand_equal_for_phi_arg_p (op0
, larger
))
1069 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1074 /* We need BOUND >= SMALLER. */
1075 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1084 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
1085 if (!operand_equal_for_phi_arg_p (lhs
, arg_false
))
1088 if (operand_equal_for_phi_arg_p (arg_true
, larger
))
1092 if (smaller > larger)
1094 r' = MIN_EXPR (smaller, bound)
1096 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
1097 if (ass_code
!= MIN_EXPR
)
1101 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1103 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1108 /* We need BOUND >= LARGER. */
1109 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1113 else if (operand_equal_for_phi_arg_p (arg_true
, smaller
))
1117 if (smaller > larger)
1119 r' = MAX_EXPR (larger, bound)
1121 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
1122 if (ass_code
!= MAX_EXPR
)
1126 if (operand_equal_for_phi_arg_p (op0
, larger
))
1128 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1133 /* We need BOUND <= SMALLER. */
1134 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1142 /* Move the statement from the middle block. */
1143 gsi
= gsi_last_bb (cond_bb
);
1144 gsi_from
= gsi_last_nondebug_bb (middle_bb
);
1145 gsi_move_before (&gsi_from
, &gsi
);
1148 /* Emit the statement to compute min/max. */
1149 result
= duplicate_ssa_name (PHI_RESULT (phi
), NULL
);
1150 new_stmt
= gimple_build_assign_with_ops (minmax
, result
, arg0
, arg1
);
1151 gsi
= gsi_last_bb (cond_bb
);
1152 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1154 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1158 /* The function absolute_replacement does the main work of doing the absolute
1159 replacement. Return true if the replacement is done. Otherwise return
1161 bb is the basic block where the replacement is going to be done on. arg0
1162 is argument 0 from the phi. Likewise for arg1. */
1165 abs_replacement (basic_block cond_bb
, basic_block middle_bb
,
1166 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1167 gimple phi
, tree arg0
, tree arg1
)
1170 gimple new_stmt
, cond
;
1171 gimple_stmt_iterator gsi
;
1172 edge true_edge
, false_edge
;
1177 enum tree_code cond_code
;
1179 /* If the type says honor signed zeros we cannot do this
1181 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
1184 /* OTHER_BLOCK must have only one executable statement which must have the
1185 form arg0 = -arg1 or arg1 = -arg0. */
1187 assign
= last_and_only_stmt (middle_bb
);
1188 /* If we did not find the proper negation assignment, then we can not
1193 /* If we got here, then we have found the only executable statement
1194 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1195 arg1 = -arg0, then we can not optimize. */
1196 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1199 lhs
= gimple_assign_lhs (assign
);
1201 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1204 rhs
= gimple_assign_rhs1 (assign
);
1206 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1207 if (!(lhs
== arg0
&& rhs
== arg1
)
1208 && !(lhs
== arg1
&& rhs
== arg0
))
1211 cond
= last_stmt (cond_bb
);
1212 result
= PHI_RESULT (phi
);
1214 /* Only relationals comparing arg[01] against zero are interesting. */
1215 cond_code
= gimple_cond_code (cond
);
1216 if (cond_code
!= GT_EXPR
&& cond_code
!= GE_EXPR
1217 && cond_code
!= LT_EXPR
&& cond_code
!= LE_EXPR
)
1220 /* Make sure the conditional is arg[01] OP y. */
1221 if (gimple_cond_lhs (cond
) != rhs
)
1224 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond
)))
1225 ? real_zerop (gimple_cond_rhs (cond
))
1226 : integer_zerop (gimple_cond_rhs (cond
)))
1231 /* We need to know which is the true edge and which is the false
1232 edge so that we know if have abs or negative abs. */
1233 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1235 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1236 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1237 the false edge goes to OTHER_BLOCK. */
1238 if (cond_code
== GT_EXPR
|| cond_code
== GE_EXPR
)
1243 if (e
->dest
== middle_bb
)
1248 result
= duplicate_ssa_name (result
, NULL
);
1251 lhs
= make_ssa_name (TREE_TYPE (result
), NULL
);
1255 /* Build the modify expression with abs expression. */
1256 new_stmt
= gimple_build_assign_with_ops (ABS_EXPR
, lhs
, rhs
, NULL
);
1258 gsi
= gsi_last_bb (cond_bb
);
1259 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1263 /* Get the right GSI. We want to insert after the recently
1264 added ABS_EXPR statement (which we know is the first statement
1266 new_stmt
= gimple_build_assign_with_ops (NEGATE_EXPR
, result
, lhs
, NULL
);
1268 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1271 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1273 /* Note that we optimized this PHI. */
1277 /* The function neg_replacement replaces conditional negation with
1278 equivalent straight line code. Returns TRUE if replacement is done,
1279 otherwise returns FALSE.
1281 COND_BB branches around negation occuring in MIDDLE_BB.
1283 E0 and E1 are edges out of COND_BB. E0 reaches MIDDLE_BB and
1284 E1 reaches the other successor which should contain PHI with
1285 arguments ARG0 and ARG1.
1287 Assuming negation is to occur when the condition is true,
1288 then the non-branching sequence is:
1290 result = (rhs ^ -cond) + cond
1292 Inverting the condition or its result gives us negation
1293 when the original condition is false. */
1296 neg_replacement (basic_block cond_bb
, basic_block middle_bb
,
1297 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1298 gimple phi
, tree arg0
, tree arg1
)
1300 gimple new_stmt
, cond
;
1301 gimple_stmt_iterator gsi
;
1303 edge true_edge
, false_edge
;
1305 enum tree_code cond_code
;
1306 bool invert
= false;
1308 /* This transformation performs logical operations on the
1309 incoming arguments. So force them to be integral types. */
1310 if (!INTEGRAL_TYPE_P (TREE_TYPE (arg0
)))
1313 /* OTHER_BLOCK must have only one executable statement which must have the
1314 form arg0 = -arg1 or arg1 = -arg0. */
1316 assign
= last_and_only_stmt (middle_bb
);
1317 /* If we did not find the proper negation assignment, then we can not
1322 /* If we got here, then we have found the only executable statement
1323 in OTHER_BLOCK. If it is anything other than arg0 = -arg1 or
1324 arg1 = -arg0, then we can not optimize. */
1325 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1328 lhs
= gimple_assign_lhs (assign
);
1330 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1333 rhs
= gimple_assign_rhs1 (assign
);
1335 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1336 if (!(lhs
== arg0
&& rhs
== arg1
)
1337 && !(lhs
== arg1
&& rhs
== arg0
))
1340 /* The basic sequence assumes we negate when the condition is true.
1341 If we need the opposite, then we will either need to invert the
1342 condition or its result. */
1343 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1344 invert
= false_edge
->dest
== middle_bb
;
1346 /* Unlike abs_replacement, we can handle arbitrary conditionals here. */
1347 cond
= last_stmt (cond_bb
);
1348 cond_code
= gimple_cond_code (cond
);
1350 /* If inversion is needed, first try to invert the test since
1355 = HONOR_NANS (TYPE_MODE (TREE_TYPE (gimple_cond_lhs (cond
))));
1356 enum tree_code new_code
= invert_tree_comparison (cond_code
, honor_nans
);
1358 /* If invert_tree_comparison was successful, then use its return
1359 value as the new code and note that inversion is no longer
1361 if (new_code
!= ERROR_MARK
)
1363 cond_code
= new_code
;
1368 tree cond_val
= make_ssa_name (boolean_type_node
, NULL
);
1369 new_stmt
= gimple_build_assign_with_ops (cond_code
, cond_val
,
1370 gimple_cond_lhs (cond
),
1371 gimple_cond_rhs (cond
));
1372 gsi
= gsi_last_bb (cond_bb
);
1373 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1375 /* If we still need inversion, then invert the result of the
1379 tree tmp
= make_ssa_name (boolean_type_node
, NULL
);
1380 new_stmt
= gimple_build_assign_with_ops (BIT_XOR_EXPR
, tmp
,
1381 cond_val
, boolean_true_node
);
1382 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1386 /* Get the condition in the right type so that we can perform
1387 logical and arithmetic operations on it. */
1388 tree cond_val_converted
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1389 new_stmt
= gimple_build_assign_with_ops (NOP_EXPR
, cond_val_converted
,
1390 cond_val
, NULL_TREE
);
1391 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1393 tree neg_cond_val_converted
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1394 new_stmt
= gimple_build_assign_with_ops (NEGATE_EXPR
, neg_cond_val_converted
,
1395 cond_val_converted
, NULL_TREE
);
1396 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1398 tree tmp
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1399 new_stmt
= gimple_build_assign_with_ops (BIT_XOR_EXPR
, tmp
,
1400 rhs
, neg_cond_val_converted
);
1401 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1403 tree new_lhs
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1404 new_stmt
= gimple_build_assign_with_ops (PLUS_EXPR
, new_lhs
,
1405 tmp
, cond_val_converted
);
1406 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1408 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_lhs
);
1410 /* Note that we optimized this PHI. */
1414 /* Auxiliary functions to determine the set of memory accesses which
1415 can't trap because they are preceded by accesses to the same memory
1416 portion. We do that for MEM_REFs, so we only need to track
1417 the SSA_NAME of the pointer indirectly referenced. The algorithm
1418 simply is a walk over all instructions in dominator order. When
1419 we see an MEM_REF we determine if we've already seen a same
1420 ref anywhere up to the root of the dominator tree. If we do the
1421 current access can't trap. If we don't see any dominating access
1422 the current access might trap, but might also make later accesses
1423 non-trapping, so we remember it. We need to be careful with loads
1424 or stores, for instance a load might not trap, while a store would,
1425 so if we see a dominating read access this doesn't mean that a later
1426 write access would not trap. Hence we also need to differentiate the
1427 type of access(es) seen.
1429 ??? We currently are very conservative and assume that a load might
1430 trap even if a store doesn't (write-only memory). This probably is
1431 overly conservative. */
1433 /* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1434 through it was seen, which would constitute a no-trap region for
1438 unsigned int ssa_name_ver
;
1441 HOST_WIDE_INT offset
, size
;
1445 /* Hashtable helpers. */
1447 struct ssa_names_hasher
: typed_free_remove
<name_to_bb
>
1449 typedef name_to_bb value_type
;
1450 typedef name_to_bb compare_type
;
1451 static inline hashval_t
hash (const value_type
*);
1452 static inline bool equal (const value_type
*, const compare_type
*);
1455 /* Used for quick clearing of the hash-table when we see calls.
1456 Hash entries with phase < nt_call_phase are invalid. */
1457 static unsigned int nt_call_phase
;
1459 /* The hash function. */
1462 ssa_names_hasher::hash (const value_type
*n
)
1464 return n
->ssa_name_ver
^ (((hashval_t
) n
->store
) << 31)
1465 ^ (n
->offset
<< 6) ^ (n
->size
<< 3);
1468 /* The equality function of *P1 and *P2. */
1471 ssa_names_hasher::equal (const value_type
*n1
, const compare_type
*n2
)
1473 return n1
->ssa_name_ver
== n2
->ssa_name_ver
1474 && n1
->store
== n2
->store
1475 && n1
->offset
== n2
->offset
1476 && n1
->size
== n2
->size
;
1479 class nontrapping_dom_walker
: public dom_walker
1482 nontrapping_dom_walker (cdi_direction direction
, hash_set
<tree
> *ps
)
1483 : dom_walker (direction
), m_nontrapping (ps
), m_seen_ssa_names (128) {}
1485 virtual void before_dom_children (basic_block
);
1486 virtual void after_dom_children (basic_block
);
1490 /* We see the expression EXP in basic block BB. If it's an interesting
1491 expression (an MEM_REF through an SSA_NAME) possibly insert the
1492 expression into the set NONTRAP or the hash table of seen expressions.
1493 STORE is true if this expression is on the LHS, otherwise it's on
1495 void add_or_mark_expr (basic_block
, tree
, bool);
1497 hash_set
<tree
> *m_nontrapping
;
1499 /* The hash table for remembering what we've seen. */
1500 hash_table
<ssa_names_hasher
> m_seen_ssa_names
;
1503 /* Called by walk_dominator_tree, when entering the block BB. */
1505 nontrapping_dom_walker::before_dom_children (basic_block bb
)
1509 gimple_stmt_iterator gsi
;
1511 /* If we haven't seen all our predecessors, clear the hash-table. */
1512 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1513 if ((((size_t)e
->src
->aux
) & 2) == 0)
1519 /* Mark this BB as being on the path to dominator root and as visited. */
1520 bb
->aux
= (void*)(1 | 2);
1522 /* And walk the statements in order. */
1523 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1525 gimple stmt
= gsi_stmt (gsi
);
1527 if (is_gimple_call (stmt
) && !nonfreeing_call_p (stmt
))
1529 else if (gimple_assign_single_p (stmt
) && !gimple_has_volatile_ops (stmt
))
1531 add_or_mark_expr (bb
, gimple_assign_lhs (stmt
), true);
1532 add_or_mark_expr (bb
, gimple_assign_rhs1 (stmt
), false);
1537 /* Called by walk_dominator_tree, when basic block BB is exited. */
1539 nontrapping_dom_walker::after_dom_children (basic_block bb
)
1541 /* This BB isn't on the path to dominator root anymore. */
1545 /* We see the expression EXP in basic block BB. If it's an interesting
1546 expression (an MEM_REF through an SSA_NAME) possibly insert the
1547 expression into the set NONTRAP or the hash table of seen expressions.
1548 STORE is true if this expression is on the LHS, otherwise it's on
1551 nontrapping_dom_walker::add_or_mark_expr (basic_block bb
, tree exp
, bool store
)
1555 if (TREE_CODE (exp
) == MEM_REF
1556 && TREE_CODE (TREE_OPERAND (exp
, 0)) == SSA_NAME
1557 && tree_fits_shwi_p (TREE_OPERAND (exp
, 1))
1558 && (size
= int_size_in_bytes (TREE_TYPE (exp
))) > 0)
1560 tree name
= TREE_OPERAND (exp
, 0);
1561 struct name_to_bb map
;
1563 struct name_to_bb
*n2bb
;
1564 basic_block found_bb
= 0;
1566 /* Try to find the last seen MEM_REF through the same
1567 SSA_NAME, which can trap. */
1568 map
.ssa_name_ver
= SSA_NAME_VERSION (name
);
1572 map
.offset
= tree_to_shwi (TREE_OPERAND (exp
, 1));
1575 slot
= m_seen_ssa_names
.find_slot (&map
, INSERT
);
1577 if (n2bb
&& n2bb
->phase
>= nt_call_phase
)
1578 found_bb
= n2bb
->bb
;
1580 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1581 (it's in a basic block on the path from us to the dominator root)
1582 then we can't trap. */
1583 if (found_bb
&& (((size_t)found_bb
->aux
) & 1) == 1)
1585 m_nontrapping
->add (exp
);
1589 /* EXP might trap, so insert it into the hash table. */
1592 n2bb
->phase
= nt_call_phase
;
1597 n2bb
= XNEW (struct name_to_bb
);
1598 n2bb
->ssa_name_ver
= SSA_NAME_VERSION (name
);
1599 n2bb
->phase
= nt_call_phase
;
1601 n2bb
->store
= store
;
1602 n2bb
->offset
= map
.offset
;
1610 /* This is the entry point of gathering non trapping memory accesses.
1611 It will do a dominator walk over the whole function, and it will
1612 make use of the bb->aux pointers. It returns a set of trees
1613 (the MEM_REFs itself) which can't trap. */
1614 static hash_set
<tree
> *
1615 get_non_trapping (void)
1618 hash_set
<tree
> *nontrap
= new hash_set
<tree
>;
1619 /* We're going to do a dominator walk, so ensure that we have
1620 dominance information. */
1621 calculate_dominance_info (CDI_DOMINATORS
);
1623 nontrapping_dom_walker (CDI_DOMINATORS
, nontrap
)
1624 .walk (cfun
->cfg
->x_entry_block_ptr
);
1626 clear_aux_for_blocks ();
1630 /* Do the main work of conditional store replacement. We already know
1631 that the recognized pattern looks like so:
1634 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1637 fallthrough (edge E0)
1641 We check that MIDDLE_BB contains only one store, that that store
1642 doesn't trap (not via NOTRAP, but via checking if an access to the same
1643 memory location dominates us) and that the store has a "simple" RHS. */
1646 cond_store_replacement (basic_block middle_bb
, basic_block join_bb
,
1647 edge e0
, edge e1
, hash_set
<tree
> *nontrap
)
1649 gimple assign
= last_and_only_stmt (middle_bb
);
1650 tree lhs
, rhs
, name
, name2
;
1651 gimple newphi
, new_stmt
;
1652 gimple_stmt_iterator gsi
;
1653 source_location locus
;
1655 /* Check if middle_bb contains of only one store. */
1657 || !gimple_assign_single_p (assign
)
1658 || gimple_has_volatile_ops (assign
))
1661 locus
= gimple_location (assign
);
1662 lhs
= gimple_assign_lhs (assign
);
1663 rhs
= gimple_assign_rhs1 (assign
);
1664 if (TREE_CODE (lhs
) != MEM_REF
1665 || TREE_CODE (TREE_OPERAND (lhs
, 0)) != SSA_NAME
1666 || !is_gimple_reg_type (TREE_TYPE (lhs
)))
1669 /* Prove that we can move the store down. We could also check
1670 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1671 whose value is not available readily, which we want to avoid. */
1672 if (!nontrap
->contains (lhs
))
1675 /* Now we've checked the constraints, so do the transformation:
1676 1) Remove the single store. */
1677 gsi
= gsi_for_stmt (assign
);
1678 unlink_stmt_vdef (assign
);
1679 gsi_remove (&gsi
, true);
1680 release_defs (assign
);
1682 /* 2) Insert a load from the memory of the store to the temporary
1683 on the edge which did not contain the store. */
1684 lhs
= unshare_expr (lhs
);
1685 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1686 new_stmt
= gimple_build_assign (name
, lhs
);
1687 gimple_set_location (new_stmt
, locus
);
1688 gsi_insert_on_edge (e1
, new_stmt
);
1690 /* 3) Create a PHI node at the join block, with one argument
1691 holding the old RHS, and the other holding the temporary
1692 where we stored the old memory contents. */
1693 name2
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1694 newphi
= create_phi_node (name2
, join_bb
);
1695 add_phi_arg (newphi
, rhs
, e0
, locus
);
1696 add_phi_arg (newphi
, name
, e1
, locus
);
1698 lhs
= unshare_expr (lhs
);
1699 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1701 /* 4) Insert that PHI node. */
1702 gsi
= gsi_after_labels (join_bb
);
1703 if (gsi_end_p (gsi
))
1705 gsi
= gsi_last_bb (join_bb
);
1706 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1709 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1714 /* Do the main work of conditional store replacement. */
1717 cond_if_else_store_replacement_1 (basic_block then_bb
, basic_block else_bb
,
1718 basic_block join_bb
, gimple then_assign
,
1721 tree lhs_base
, lhs
, then_rhs
, else_rhs
, name
;
1722 source_location then_locus
, else_locus
;
1723 gimple_stmt_iterator gsi
;
1724 gimple newphi
, new_stmt
;
1726 if (then_assign
== NULL
1727 || !gimple_assign_single_p (then_assign
)
1728 || gimple_clobber_p (then_assign
)
1729 || gimple_has_volatile_ops (then_assign
)
1730 || else_assign
== NULL
1731 || !gimple_assign_single_p (else_assign
)
1732 || gimple_clobber_p (else_assign
)
1733 || gimple_has_volatile_ops (else_assign
))
1736 lhs
= gimple_assign_lhs (then_assign
);
1737 if (!is_gimple_reg_type (TREE_TYPE (lhs
))
1738 || !operand_equal_p (lhs
, gimple_assign_lhs (else_assign
), 0))
1741 lhs_base
= get_base_address (lhs
);
1742 if (lhs_base
== NULL_TREE
1743 || (!DECL_P (lhs_base
) && TREE_CODE (lhs_base
) != MEM_REF
))
1746 then_rhs
= gimple_assign_rhs1 (then_assign
);
1747 else_rhs
= gimple_assign_rhs1 (else_assign
);
1748 then_locus
= gimple_location (then_assign
);
1749 else_locus
= gimple_location (else_assign
);
1751 /* Now we've checked the constraints, so do the transformation:
1752 1) Remove the stores. */
1753 gsi
= gsi_for_stmt (then_assign
);
1754 unlink_stmt_vdef (then_assign
);
1755 gsi_remove (&gsi
, true);
1756 release_defs (then_assign
);
1758 gsi
= gsi_for_stmt (else_assign
);
1759 unlink_stmt_vdef (else_assign
);
1760 gsi_remove (&gsi
, true);
1761 release_defs (else_assign
);
1763 /* 2) Create a PHI node at the join block, with one argument
1764 holding the old RHS, and the other holding the temporary
1765 where we stored the old memory contents. */
1766 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1767 newphi
= create_phi_node (name
, join_bb
);
1768 add_phi_arg (newphi
, then_rhs
, EDGE_SUCC (then_bb
, 0), then_locus
);
1769 add_phi_arg (newphi
, else_rhs
, EDGE_SUCC (else_bb
, 0), else_locus
);
1771 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1773 /* 3) Insert that PHI node. */
1774 gsi
= gsi_after_labels (join_bb
);
1775 if (gsi_end_p (gsi
))
1777 gsi
= gsi_last_bb (join_bb
);
1778 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1781 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1786 /* Conditional store replacement. We already know
1787 that the recognized pattern looks like so:
1790 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
1800 fallthrough (edge E0)
1804 We check that it is safe to sink the store to JOIN_BB by verifying that
1805 there are no read-after-write or write-after-write dependencies in
1806 THEN_BB and ELSE_BB. */
1809 cond_if_else_store_replacement (basic_block then_bb
, basic_block else_bb
,
1810 basic_block join_bb
)
1812 gimple then_assign
= last_and_only_stmt (then_bb
);
1813 gimple else_assign
= last_and_only_stmt (else_bb
);
1814 vec
<data_reference_p
> then_datarefs
, else_datarefs
;
1815 vec
<ddr_p
> then_ddrs
, else_ddrs
;
1816 gimple then_store
, else_store
;
1817 bool found
, ok
= false, res
;
1818 struct data_dependence_relation
*ddr
;
1819 data_reference_p then_dr
, else_dr
;
1821 tree then_lhs
, else_lhs
;
1822 basic_block blocks
[3];
1824 if (MAX_STORES_TO_SINK
== 0)
1827 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
1828 if (then_assign
&& else_assign
)
1829 return cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1830 then_assign
, else_assign
);
1832 /* Find data references. */
1833 then_datarefs
.create (1);
1834 else_datarefs
.create (1);
1835 if ((find_data_references_in_bb (NULL
, then_bb
, &then_datarefs
)
1837 || !then_datarefs
.length ()
1838 || (find_data_references_in_bb (NULL
, else_bb
, &else_datarefs
)
1840 || !else_datarefs
.length ())
1842 free_data_refs (then_datarefs
);
1843 free_data_refs (else_datarefs
);
1847 /* Find pairs of stores with equal LHS. */
1848 auto_vec
<gimple
, 1> then_stores
, else_stores
;
1849 FOR_EACH_VEC_ELT (then_datarefs
, i
, then_dr
)
1851 if (DR_IS_READ (then_dr
))
1854 then_store
= DR_STMT (then_dr
);
1855 then_lhs
= gimple_get_lhs (then_store
);
1856 if (then_lhs
== NULL_TREE
)
1860 FOR_EACH_VEC_ELT (else_datarefs
, j
, else_dr
)
1862 if (DR_IS_READ (else_dr
))
1865 else_store
= DR_STMT (else_dr
);
1866 else_lhs
= gimple_get_lhs (else_store
);
1867 if (else_lhs
== NULL_TREE
)
1870 if (operand_equal_p (then_lhs
, else_lhs
, 0))
1880 then_stores
.safe_push (then_store
);
1881 else_stores
.safe_push (else_store
);
1884 /* No pairs of stores found. */
1885 if (!then_stores
.length ()
1886 || then_stores
.length () > (unsigned) MAX_STORES_TO_SINK
)
1888 free_data_refs (then_datarefs
);
1889 free_data_refs (else_datarefs
);
1893 /* Compute and check data dependencies in both basic blocks. */
1894 then_ddrs
.create (1);
1895 else_ddrs
.create (1);
1896 if (!compute_all_dependences (then_datarefs
, &then_ddrs
,
1898 || !compute_all_dependences (else_datarefs
, &else_ddrs
,
1901 free_dependence_relations (then_ddrs
);
1902 free_dependence_relations (else_ddrs
);
1903 free_data_refs (then_datarefs
);
1904 free_data_refs (else_datarefs
);
1907 blocks
[0] = then_bb
;
1908 blocks
[1] = else_bb
;
1909 blocks
[2] = join_bb
;
1910 renumber_gimple_stmt_uids_in_blocks (blocks
, 3);
1912 /* Check that there are no read-after-write or write-after-write dependencies
1914 FOR_EACH_VEC_ELT (then_ddrs
, i
, ddr
)
1916 struct data_reference
*dra
= DDR_A (ddr
);
1917 struct data_reference
*drb
= DDR_B (ddr
);
1919 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1920 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1921 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1922 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1923 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1924 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1926 free_dependence_relations (then_ddrs
);
1927 free_dependence_relations (else_ddrs
);
1928 free_data_refs (then_datarefs
);
1929 free_data_refs (else_datarefs
);
1934 /* Check that there are no read-after-write or write-after-write dependencies
1936 FOR_EACH_VEC_ELT (else_ddrs
, i
, ddr
)
1938 struct data_reference
*dra
= DDR_A (ddr
);
1939 struct data_reference
*drb
= DDR_B (ddr
);
1941 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1942 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1943 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1944 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1945 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1946 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1948 free_dependence_relations (then_ddrs
);
1949 free_dependence_relations (else_ddrs
);
1950 free_data_refs (then_datarefs
);
1951 free_data_refs (else_datarefs
);
1956 /* Sink stores with same LHS. */
1957 FOR_EACH_VEC_ELT (then_stores
, i
, then_store
)
1959 else_store
= else_stores
[i
];
1960 res
= cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1961 then_store
, else_store
);
1965 free_dependence_relations (then_ddrs
);
1966 free_dependence_relations (else_ddrs
);
1967 free_data_refs (then_datarefs
);
1968 free_data_refs (else_datarefs
);
1973 /* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
1976 local_mem_dependence (gimple stmt
, basic_block bb
)
1978 tree vuse
= gimple_vuse (stmt
);
1984 def
= SSA_NAME_DEF_STMT (vuse
);
1985 return (def
&& gimple_bb (def
) == bb
);
1988 /* Given a "diamond" control-flow pattern where BB0 tests a condition,
1989 BB1 and BB2 are "then" and "else" blocks dependent on this test,
1990 and BB3 rejoins control flow following BB1 and BB2, look for
1991 opportunities to hoist loads as follows. If BB3 contains a PHI of
1992 two loads, one each occurring in BB1 and BB2, and the loads are
1993 provably of adjacent fields in the same structure, then move both
1994 loads into BB0. Of course this can only be done if there are no
1995 dependencies preventing such motion.
1997 One of the hoisted loads will always be speculative, so the
1998 transformation is currently conservative:
2000 - The fields must be strictly adjacent.
2001 - The two fields must occupy a single memory block that is
2002 guaranteed to not cross a page boundary.
2004 The last is difficult to prove, as such memory blocks should be
2005 aligned on the minimum of the stack alignment boundary and the
2006 alignment guaranteed by heap allocation interfaces. Thus we rely
2007 on a parameter for the alignment value.
2009 Provided a good value is used for the last case, the first
2010 restriction could possibly be relaxed. */
2013 hoist_adjacent_loads (basic_block bb0
, basic_block bb1
,
2014 basic_block bb2
, basic_block bb3
)
2016 int param_align
= PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
);
2017 unsigned param_align_bits
= (unsigned) (param_align
* BITS_PER_UNIT
);
2018 gimple_stmt_iterator gsi
;
2020 /* Walk the phis in bb3 looking for an opportunity. We are looking
2021 for phis of two SSA names, one each of which is defined in bb1 and
2023 for (gsi
= gsi_start_phis (bb3
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2025 gimple phi_stmt
= gsi_stmt (gsi
);
2026 gimple def1
, def2
, defswap
;
2027 tree arg1
, arg2
, ref1
, ref2
, field1
, field2
, fieldswap
;
2028 tree tree_offset1
, tree_offset2
, tree_size2
, next
;
2029 int offset1
, offset2
, size2
;
2031 gimple_stmt_iterator gsi2
;
2032 basic_block bb_for_def1
, bb_for_def2
;
2034 if (gimple_phi_num_args (phi_stmt
) != 2
2035 || virtual_operand_p (gimple_phi_result (phi_stmt
)))
2038 arg1
= gimple_phi_arg_def (phi_stmt
, 0);
2039 arg2
= gimple_phi_arg_def (phi_stmt
, 1);
2041 if (TREE_CODE (arg1
) != SSA_NAME
2042 || TREE_CODE (arg2
) != SSA_NAME
2043 || SSA_NAME_IS_DEFAULT_DEF (arg1
)
2044 || SSA_NAME_IS_DEFAULT_DEF (arg2
))
2047 def1
= SSA_NAME_DEF_STMT (arg1
);
2048 def2
= SSA_NAME_DEF_STMT (arg2
);
2050 if ((gimple_bb (def1
) != bb1
|| gimple_bb (def2
) != bb2
)
2051 && (gimple_bb (def2
) != bb1
|| gimple_bb (def1
) != bb2
))
2054 /* Check the mode of the arguments to be sure a conditional move
2055 can be generated for it. */
2056 if (optab_handler (movcc_optab
, TYPE_MODE (TREE_TYPE (arg1
)))
2057 == CODE_FOR_nothing
)
2060 /* Both statements must be assignments whose RHS is a COMPONENT_REF. */
2061 if (!gimple_assign_single_p (def1
)
2062 || !gimple_assign_single_p (def2
)
2063 || gimple_has_volatile_ops (def1
)
2064 || gimple_has_volatile_ops (def2
))
2067 ref1
= gimple_assign_rhs1 (def1
);
2068 ref2
= gimple_assign_rhs1 (def2
);
2070 if (TREE_CODE (ref1
) != COMPONENT_REF
2071 || TREE_CODE (ref2
) != COMPONENT_REF
)
2074 /* The zeroth operand of the two component references must be
2075 identical. It is not sufficient to compare get_base_address of
2076 the two references, because this could allow for different
2077 elements of the same array in the two trees. It is not safe to
2078 assume that the existence of one array element implies the
2079 existence of a different one. */
2080 if (!operand_equal_p (TREE_OPERAND (ref1
, 0), TREE_OPERAND (ref2
, 0), 0))
2083 field1
= TREE_OPERAND (ref1
, 1);
2084 field2
= TREE_OPERAND (ref2
, 1);
2086 /* Check for field adjacency, and ensure field1 comes first. */
2087 for (next
= DECL_CHAIN (field1
);
2088 next
&& TREE_CODE (next
) != FIELD_DECL
;
2089 next
= DECL_CHAIN (next
))
2094 for (next
= DECL_CHAIN (field2
);
2095 next
&& TREE_CODE (next
) != FIELD_DECL
;
2096 next
= DECL_CHAIN (next
))
2110 bb_for_def1
= gimple_bb (def1
);
2111 bb_for_def2
= gimple_bb (def2
);
2113 /* Check for proper alignment of the first field. */
2114 tree_offset1
= bit_position (field1
);
2115 tree_offset2
= bit_position (field2
);
2116 tree_size2
= DECL_SIZE (field2
);
2118 if (!tree_fits_uhwi_p (tree_offset1
)
2119 || !tree_fits_uhwi_p (tree_offset2
)
2120 || !tree_fits_uhwi_p (tree_size2
))
2123 offset1
= tree_to_uhwi (tree_offset1
);
2124 offset2
= tree_to_uhwi (tree_offset2
);
2125 size2
= tree_to_uhwi (tree_size2
);
2126 align1
= DECL_ALIGN (field1
) % param_align_bits
;
2128 if (offset1
% BITS_PER_UNIT
!= 0)
2131 /* For profitability, the two field references should fit within
2132 a single cache line. */
2133 if (align1
+ offset2
- offset1
+ size2
> param_align_bits
)
2136 /* The two expressions cannot be dependent upon vdefs defined
2138 if (local_mem_dependence (def1
, bb_for_def1
)
2139 || local_mem_dependence (def2
, bb_for_def2
))
2142 /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
2143 bb0. We hoist the first one first so that a cache miss is handled
2144 efficiently regardless of hardware cache-fill policy. */
2145 gsi2
= gsi_for_stmt (def1
);
2146 gsi_move_to_bb_end (&gsi2
, bb0
);
2147 gsi2
= gsi_for_stmt (def2
);
2148 gsi_move_to_bb_end (&gsi2
, bb0
);
2150 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2153 "\nHoisting adjacent loads from %d and %d into %d: \n",
2154 bb_for_def1
->index
, bb_for_def2
->index
, bb0
->index
);
2155 print_gimple_stmt (dump_file
, def1
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2156 print_gimple_stmt (dump_file
, def2
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2161 /* Determine whether we should attempt to hoist adjacent loads out of
2162 diamond patterns in pass_phiopt. Always hoist loads if
2163 -fhoist-adjacent-loads is specified and the target machine has
2164 both a conditional move instruction and a defined cache line size. */
2167 gate_hoist_loads (void)
2169 return (flag_hoist_adjacent_loads
== 1
2170 && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
)
2171 && HAVE_conditional_move
);
2174 /* This pass tries to replaces an if-then-else block with an
2175 assignment. We have four kinds of transformations. Some of these
2176 transformations are also performed by the ifcvt RTL optimizer.
2178 Conditional Replacement
2179 -----------------------
2181 This transformation, implemented in conditional_replacement,
2185 if (cond) goto bb2; else goto bb1;
2188 x = PHI <0 (bb1), 1 (bb0), ...>;
2196 x = PHI <x' (bb0), ...>;
2198 We remove bb1 as it becomes unreachable. This occurs often due to
2199 gimplification of conditionals.
2204 This transformation, implemented in value_replacement, replaces
2207 if (a != b) goto bb2; else goto bb1;
2210 x = PHI <a (bb1), b (bb0), ...>;
2216 x = PHI <b (bb0), ...>;
2218 This opportunity can sometimes occur as a result of other
2222 Another case caught by value replacement looks like this:
2228 if (t3 != 0) goto bb1; else goto bb2;
2244 This transformation, implemented in abs_replacement, replaces
2247 if (a >= 0) goto bb2; else goto bb1;
2251 x = PHI <x (bb1), a (bb0), ...>;
2258 x = PHI <x' (bb0), ...>;
2263 This transformation, minmax_replacement replaces
2266 if (a <= b) goto bb2; else goto bb1;
2269 x = PHI <b (bb1), a (bb0), ...>;
2274 x' = MIN_EXPR (a, b)
2276 x = PHI <x' (bb0), ...>;
2278 A similar transformation is done for MAX_EXPR.
2281 This pass also performs a fifth transformation of a slightly different
2284 Adjacent Load Hoisting
2285 ----------------------
2287 This transformation replaces
2290 if (...) goto bb2; else goto bb1;
2292 x1 = (<expr>).field1;
2295 x2 = (<expr>).field2;
2302 x1 = (<expr>).field1;
2303 x2 = (<expr>).field2;
2304 if (...) goto bb2; else goto bb1;
2311 The purpose of this transformation is to enable generation of conditional
2312 move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
2313 the loads is speculative, the transformation is restricted to very
2314 specific cases to avoid introducing a page fault. We are looking for
2322 where left and right are typically adjacent pointers in a tree structure. */
2326 const pass_data pass_data_phiopt
=
2328 GIMPLE_PASS
, /* type */
2329 "phiopt", /* name */
2330 OPTGROUP_NONE
, /* optinfo_flags */
2331 TV_TREE_PHIOPT
, /* tv_id */
2332 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2333 0, /* properties_provided */
2334 0, /* properties_destroyed */
2335 0, /* todo_flags_start */
2336 0, /* todo_flags_finish */
2339 class pass_phiopt
: public gimple_opt_pass
2342 pass_phiopt (gcc::context
*ctxt
)
2343 : gimple_opt_pass (pass_data_phiopt
, ctxt
)
2346 /* opt_pass methods: */
2347 opt_pass
* clone () { return new pass_phiopt (m_ctxt
); }
2348 virtual bool gate (function
*) { return flag_ssa_phiopt
; }
2349 virtual unsigned int execute (function
*)
2351 return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
2354 }; // class pass_phiopt
2359 make_pass_phiopt (gcc::context
*ctxt
)
2361 return new pass_phiopt (ctxt
);
2366 const pass_data pass_data_cselim
=
2368 GIMPLE_PASS
, /* type */
2369 "cselim", /* name */
2370 OPTGROUP_NONE
, /* optinfo_flags */
2371 TV_TREE_PHIOPT
, /* tv_id */
2372 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2373 0, /* properties_provided */
2374 0, /* properties_destroyed */
2375 0, /* todo_flags_start */
2376 0, /* todo_flags_finish */
2379 class pass_cselim
: public gimple_opt_pass
2382 pass_cselim (gcc::context
*ctxt
)
2383 : gimple_opt_pass (pass_data_cselim
, ctxt
)
2386 /* opt_pass methods: */
2387 virtual bool gate (function
*) { return flag_tree_cselim
; }
2388 virtual unsigned int execute (function
*) { return tree_ssa_cs_elim (); }
2390 }; // class pass_cselim
2395 make_pass_cselim (gcc::context
*ctxt
)
2397 return new pass_cselim (ctxt
);