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"
29 #include "basic-block.h"
31 #include "tree-ssa-alias.h"
32 #include "internal-fn.h"
33 #include "gimple-expr.h"
37 #include "gimple-iterator.h"
38 #include "gimplify-me.h"
39 #include "gimple-ssa.h"
41 #include "tree-phinodes.h"
42 #include "ssa-iterators.h"
43 #include "stringpool.h"
44 #include "tree-ssanames.h"
47 #include "tree-pass.h"
48 #include "langhooks.h"
51 #include "tree-data-ref.h"
52 #include "gimple-pretty-print.h"
53 #include "insn-config.h"
56 #include "tree-scalar-evolution.h"
57 #include "tree-inline.h"
59 #ifndef HAVE_conditional_move
60 #define HAVE_conditional_move (0)
63 static unsigned int tree_ssa_phiopt_worker (bool, bool);
64 static bool conditional_replacement (basic_block
, basic_block
,
65 edge
, edge
, gimple_phi
, tree
, tree
);
66 static int value_replacement (basic_block
, basic_block
,
67 edge
, edge
, gimple
, tree
, tree
);
68 static bool minmax_replacement (basic_block
, basic_block
,
69 edge
, edge
, gimple
, tree
, tree
);
70 static bool abs_replacement (basic_block
, basic_block
,
71 edge
, edge
, gimple
, tree
, tree
);
72 static bool neg_replacement (basic_block
, basic_block
,
73 edge
, edge
, gimple
, tree
, tree
);
74 static bool cond_store_replacement (basic_block
, basic_block
, edge
, edge
,
76 static bool cond_if_else_store_replacement (basic_block
, basic_block
, basic_block
);
77 static hash_set
<tree
> * get_non_trapping ();
78 static void replace_phi_edge_with_variable (basic_block
, edge
, gimple
, tree
);
79 static void hoist_adjacent_loads (basic_block
, basic_block
,
80 basic_block
, basic_block
);
81 static bool gate_hoist_loads (void);
83 /* This pass tries to transform conditional stores into unconditional
84 ones, enabling further simplifications with the simpler then and else
85 blocks. In particular it replaces this:
88 if (cond) goto bb2; else goto bb1;
96 if (cond) goto bb1; else goto bb2;
100 condtmp = PHI <RHS, condtmp'>
103 This transformation can only be done under several constraints,
104 documented below. It also replaces:
107 if (cond) goto bb2; else goto bb1;
118 if (cond) goto bb3; else goto bb1;
121 condtmp = PHI <RHS1, RHS2>
125 tree_ssa_cs_elim (void)
128 /* ??? We are not interested in loop related info, but the following
129 will create it, ICEing as we didn't init loops with pre-headers.
130 An interfacing issue of find_data_references_in_bb. */
131 loop_optimizer_init (LOOPS_NORMAL
);
133 todo
= tree_ssa_phiopt_worker (true, false);
135 loop_optimizer_finalize ();
139 /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
142 single_non_singleton_phi_for_edges (gimple_seq seq
, edge e0
, edge e1
)
144 gimple_stmt_iterator i
;
145 gimple_phi phi
= NULL
;
146 if (gimple_seq_singleton_p (seq
))
147 return as_a
<gimple_phi
> (gsi_stmt (gsi_start (seq
)));
148 for (i
= gsi_start (seq
); !gsi_end_p (i
); gsi_next (&i
))
150 gimple_phi p
= as_a
<gimple_phi
> (gsi_stmt (i
));
151 /* If the PHI arguments are equal then we can skip this PHI. */
152 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p
, e0
->dest_idx
),
153 gimple_phi_arg_def (p
, e1
->dest_idx
)))
156 /* If we already have a PHI that has the two edge arguments are
157 different, then return it is not a singleton for these PHIs. */
166 /* The core routine of conditional store replacement and normal
167 phi optimizations. Both share much of the infrastructure in how
168 to match applicable basic block patterns. DO_STORE_ELIM is true
169 when we want to do conditional store replacement, false otherwise.
170 DO_HOIST_LOADS is true when we want to hoist adjacent loads out
171 of diamond control flow patterns, false otherwise. */
173 tree_ssa_phiopt_worker (bool do_store_elim
, bool do_hoist_loads
)
176 basic_block
*bb_order
;
178 bool cfgchanged
= false;
179 hash_set
<tree
> *nontrap
= 0;
182 /* Calculate the set of non-trapping memory accesses. */
183 nontrap
= get_non_trapping ();
185 /* The replacement of conditional negation with a non-branching
186 sequence is really only a win when optimizing for speed and we
187 can avoid transformations by gimple if-conversion that result
188 in poor RTL generation.
190 Ideally either gimple if-conversion or the RTL expanders will
191 be improved and the code to emit branchless conditional negation
193 bool replace_conditional_negation
= false;
195 replace_conditional_negation
196 = ((!optimize_size
&& optimize
>= 2)
197 || (((flag_tree_loop_vectorize
|| cfun
->has_force_vectorize_loops
)
198 && flag_tree_loop_if_convert
!= 0)
199 || flag_tree_loop_if_convert
== 1
200 || flag_tree_loop_if_convert_stores
== 1));
202 /* Search every basic block for COND_EXPR we may be able to optimize.
204 We walk the blocks in order that guarantees that a block with
205 a single predecessor is processed before the predecessor.
206 This ensures that we collapse inner ifs before visiting the
207 outer ones, and also that we do not try to visit a removed
209 bb_order
= single_pred_before_succ_order ();
210 n
= n_basic_blocks_for_fn (cfun
) - NUM_FIXED_BLOCKS
;
212 for (i
= 0; i
< n
; i
++)
216 basic_block bb1
, bb2
;
222 cond_stmt
= last_stmt (bb
);
223 /* Check to see if the last statement is a GIMPLE_COND. */
225 || gimple_code (cond_stmt
) != GIMPLE_COND
)
228 e1
= EDGE_SUCC (bb
, 0);
230 e2
= EDGE_SUCC (bb
, 1);
233 /* We cannot do the optimization on abnormal edges. */
234 if ((e1
->flags
& EDGE_ABNORMAL
) != 0
235 || (e2
->flags
& EDGE_ABNORMAL
) != 0)
238 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
239 if (EDGE_COUNT (bb1
->succs
) == 0
241 || EDGE_COUNT (bb2
->succs
) == 0)
244 /* Find the bb which is the fall through to the other. */
245 if (EDGE_SUCC (bb1
, 0)->dest
== bb2
)
247 else if (EDGE_SUCC (bb2
, 0)->dest
== bb1
)
249 basic_block bb_tmp
= bb1
;
256 else if (do_store_elim
257 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
259 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
261 if (!single_succ_p (bb1
)
262 || (EDGE_SUCC (bb1
, 0)->flags
& EDGE_FALLTHRU
) == 0
263 || !single_succ_p (bb2
)
264 || (EDGE_SUCC (bb2
, 0)->flags
& EDGE_FALLTHRU
) == 0
265 || EDGE_COUNT (bb3
->preds
) != 2)
267 if (cond_if_else_store_replacement (bb1
, bb2
, bb3
))
271 else if (do_hoist_loads
272 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
274 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
276 if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt
)))
277 && single_succ_p (bb1
)
278 && single_succ_p (bb2
)
279 && single_pred_p (bb1
)
280 && single_pred_p (bb2
)
281 && EDGE_COUNT (bb
->succs
) == 2
282 && EDGE_COUNT (bb3
->preds
) == 2
283 /* If one edge or the other is dominant, a conditional move
284 is likely to perform worse than the well-predicted branch. */
285 && !predictable_edge_p (EDGE_SUCC (bb
, 0))
286 && !predictable_edge_p (EDGE_SUCC (bb
, 1)))
287 hoist_adjacent_loads (bb
, bb1
, bb2
, bb3
);
293 e1
= EDGE_SUCC (bb1
, 0);
295 /* Make sure that bb1 is just a fall through. */
296 if (!single_succ_p (bb1
)
297 || (e1
->flags
& EDGE_FALLTHRU
) == 0)
300 /* Also make sure that bb1 only have one predecessor and that it
302 if (!single_pred_p (bb1
)
303 || single_pred (bb1
) != bb
)
308 /* bb1 is the middle block, bb2 the join block, bb the split block,
309 e1 the fallthrough edge from bb1 to bb2. We can't do the
310 optimization if the join block has more than two predecessors. */
311 if (EDGE_COUNT (bb2
->preds
) > 2)
313 if (cond_store_replacement (bb1
, bb2
, e1
, e2
, nontrap
))
318 gimple_seq phis
= phi_nodes (bb2
);
319 gimple_stmt_iterator gsi
;
320 bool candorest
= true;
322 /* Value replacement can work with more than one PHI
323 so try that first. */
324 for (gsi
= gsi_start (phis
); !gsi_end_p (gsi
); gsi_next (&gsi
))
326 phi
= as_a
<gimple_phi
> (gsi_stmt (gsi
));
327 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
328 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
329 if (value_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
) == 2)
340 phi
= single_non_singleton_phi_for_edges (phis
, e1
, e2
);
344 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
345 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
347 /* Something is wrong if we cannot find the arguments in the PHI
349 gcc_assert (arg0
!= NULL
&& arg1
!= NULL
);
351 /* Do the replacement of conditional if it can be done. */
352 if (conditional_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
354 else if (abs_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
356 else if (replace_conditional_negation
357 && neg_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
359 else if (minmax_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
368 /* If the CFG has changed, we should cleanup the CFG. */
369 if (cfgchanged
&& do_store_elim
)
371 /* In cond-store replacement we have added some loads on edges
372 and new VOPS (as we moved the store, and created a load). */
373 gsi_commit_edge_inserts ();
374 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
377 return TODO_cleanup_cfg
;
381 /* Replace PHI node element whose edge is E in block BB with variable NEW.
382 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
383 is known to have two edges, one of which must reach BB). */
386 replace_phi_edge_with_variable (basic_block cond_block
,
387 edge e
, gimple phi
, tree new_tree
)
389 basic_block bb
= gimple_bb (phi
);
390 basic_block block_to_remove
;
391 gimple_stmt_iterator gsi
;
393 /* Change the PHI argument to new. */
394 SET_USE (PHI_ARG_DEF_PTR (phi
, e
->dest_idx
), new_tree
);
396 /* Remove the empty basic block. */
397 if (EDGE_SUCC (cond_block
, 0)->dest
== bb
)
399 EDGE_SUCC (cond_block
, 0)->flags
|= EDGE_FALLTHRU
;
400 EDGE_SUCC (cond_block
, 0)->flags
&= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
401 EDGE_SUCC (cond_block
, 0)->probability
= REG_BR_PROB_BASE
;
402 EDGE_SUCC (cond_block
, 0)->count
+= EDGE_SUCC (cond_block
, 1)->count
;
404 block_to_remove
= EDGE_SUCC (cond_block
, 1)->dest
;
408 EDGE_SUCC (cond_block
, 1)->flags
|= EDGE_FALLTHRU
;
409 EDGE_SUCC (cond_block
, 1)->flags
410 &= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
411 EDGE_SUCC (cond_block
, 1)->probability
= REG_BR_PROB_BASE
;
412 EDGE_SUCC (cond_block
, 1)->count
+= EDGE_SUCC (cond_block
, 0)->count
;
414 block_to_remove
= EDGE_SUCC (cond_block
, 0)->dest
;
416 delete_basic_block (block_to_remove
);
418 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
419 gsi
= gsi_last_bb (cond_block
);
420 gsi_remove (&gsi
, true);
422 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
424 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
429 /* The function conditional_replacement does the main work of doing the
430 conditional replacement. Return true if the replacement is done.
431 Otherwise return false.
432 BB is the basic block where the replacement is going to be done on. ARG0
433 is argument 0 from PHI. Likewise for ARG1. */
436 conditional_replacement (basic_block cond_bb
, basic_block middle_bb
,
437 edge e0
, edge e1
, gimple_phi phi
,
438 tree arg0
, tree arg1
)
442 gimple_assign new_stmt
;
444 gimple_stmt_iterator gsi
;
445 edge true_edge
, false_edge
;
446 tree new_var
, new_var2
;
449 /* FIXME: Gimplification of complex type is too hard for now. */
450 /* We aren't prepared to handle vectors either (and it is a question
451 if it would be worthwhile anyway). */
452 if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
453 || POINTER_TYPE_P (TREE_TYPE (arg0
)))
454 || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1
))
455 || POINTER_TYPE_P (TREE_TYPE (arg1
))))
458 /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
459 convert it to the conditional. */
460 if ((integer_zerop (arg0
) && integer_onep (arg1
))
461 || (integer_zerop (arg1
) && integer_onep (arg0
)))
463 else if ((integer_zerop (arg0
) && integer_all_onesp (arg1
))
464 || (integer_zerop (arg1
) && integer_all_onesp (arg0
)))
469 if (!empty_block_p (middle_bb
))
472 /* At this point we know we have a GIMPLE_COND with two successors.
473 One successor is BB, the other successor is an empty block which
474 falls through into BB.
476 There is a single PHI node at the join point (BB) and its arguments
477 are constants (0, 1) or (0, -1).
479 So, given the condition COND, and the two PHI arguments, we can
480 rewrite this PHI into non-branching code:
482 dest = (COND) or dest = COND'
484 We use the condition as-is if the argument associated with the
485 true edge has the value one or the argument associated with the
486 false edge as the value zero. Note that those conditions are not
487 the same since only one of the outgoing edges from the GIMPLE_COND
488 will directly reach BB and thus be associated with an argument. */
490 stmt
= last_stmt (cond_bb
);
491 result
= PHI_RESULT (phi
);
493 /* To handle special cases like floating point comparison, it is easier and
494 less error-prone to build a tree and gimplify it on the fly though it is
496 cond
= fold_build2_loc (gimple_location (stmt
),
497 gimple_cond_code (stmt
), boolean_type_node
,
498 gimple_cond_lhs (stmt
), gimple_cond_rhs (stmt
));
500 /* We need to know which is the true edge and which is the false
501 edge so that we know when to invert the condition below. */
502 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
503 if ((e0
== true_edge
&& integer_zerop (arg0
))
504 || (e0
== false_edge
&& !integer_zerop (arg0
))
505 || (e1
== true_edge
&& integer_zerop (arg1
))
506 || (e1
== false_edge
&& !integer_zerop (arg1
)))
507 cond
= fold_build1_loc (gimple_location (stmt
),
508 TRUTH_NOT_EXPR
, TREE_TYPE (cond
), cond
);
512 cond
= fold_convert_loc (gimple_location (stmt
),
513 TREE_TYPE (result
), cond
);
514 cond
= fold_build1_loc (gimple_location (stmt
),
515 NEGATE_EXPR
, TREE_TYPE (cond
), cond
);
518 /* Insert our new statements at the end of conditional block before the
520 gsi
= gsi_for_stmt (stmt
);
521 new_var
= force_gimple_operand_gsi (&gsi
, cond
, true, NULL
, true,
524 if (!useless_type_conversion_p (TREE_TYPE (result
), TREE_TYPE (new_var
)))
526 source_location locus_0
, locus_1
;
528 new_var2
= make_ssa_name (TREE_TYPE (result
), NULL
);
529 new_stmt
= gimple_build_assign_with_ops (CONVERT_EXPR
, new_var2
,
531 gsi_insert_before (&gsi
, new_stmt
, GSI_SAME_STMT
);
534 /* Set the locus to the first argument, unless is doesn't have one. */
535 locus_0
= gimple_phi_arg_location (phi
, 0);
536 locus_1
= gimple_phi_arg_location (phi
, 1);
537 if (locus_0
== UNKNOWN_LOCATION
)
539 gimple_set_location (new_stmt
, locus_0
);
542 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_var
);
544 /* Note that we optimized this PHI. */
548 /* Update *ARG which is defined in STMT so that it contains the
549 computed value if that seems profitable. Return true if the
550 statement is made dead by that rewriting. */
553 jump_function_from_stmt (tree
*arg
, gimple stmt
)
555 enum tree_code code
= gimple_assign_rhs_code (stmt
);
556 if (code
== ADDR_EXPR
)
558 /* For arg = &p->i transform it to p, if possible. */
559 tree rhs1
= gimple_assign_rhs1 (stmt
);
560 HOST_WIDE_INT offset
;
561 tree tem
= get_addr_base_and_unit_offset (TREE_OPERAND (rhs1
, 0),
564 && TREE_CODE (tem
) == MEM_REF
565 && (mem_ref_offset (tem
) + offset
) == 0)
567 *arg
= TREE_OPERAND (tem
, 0);
571 /* TODO: Much like IPA-CP jump-functions we want to handle constant
572 additions symbolically here, and we'd need to update the comparison
573 code that compares the arg + cst tuples in our caller. For now the
574 code above exactly handles the VEC_BASE pattern from vec.h. */
578 /* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
579 of the form SSA_NAME NE 0.
581 If RHS is fed by a simple EQ_EXPR comparison of two values, see if
582 the two input values of the EQ_EXPR match arg0 and arg1.
584 If so update *code and return TRUE. Otherwise return FALSE. */
587 rhs_is_fed_for_value_replacement (const_tree arg0
, const_tree arg1
,
588 enum tree_code
*code
, const_tree rhs
)
590 /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
592 if (TREE_CODE (rhs
) == SSA_NAME
)
594 gimple def1
= SSA_NAME_DEF_STMT (rhs
);
596 /* Verify the defining statement has an EQ_EXPR on the RHS. */
597 if (is_gimple_assign (def1
) && gimple_assign_rhs_code (def1
) == EQ_EXPR
)
599 /* Finally verify the source operands of the EQ_EXPR are equal
601 tree op0
= gimple_assign_rhs1 (def1
);
602 tree op1
= gimple_assign_rhs2 (def1
);
603 if ((operand_equal_for_phi_arg_p (arg0
, op0
)
604 && operand_equal_for_phi_arg_p (arg1
, op1
))
605 || (operand_equal_for_phi_arg_p (arg0
, op1
)
606 && operand_equal_for_phi_arg_p (arg1
, op0
)))
608 /* We will perform the optimization. */
609 *code
= gimple_assign_rhs_code (def1
);
617 /* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
619 Also return TRUE if arg0/arg1 are equal to the source arguments of a
620 an EQ comparison feeding a BIT_AND_EXPR which feeds COND.
622 Return FALSE otherwise. */
625 operand_equal_for_value_replacement (const_tree arg0
, const_tree arg1
,
626 enum tree_code
*code
, gimple cond
)
629 tree lhs
= gimple_cond_lhs (cond
);
630 tree rhs
= gimple_cond_rhs (cond
);
632 if ((operand_equal_for_phi_arg_p (arg0
, lhs
)
633 && operand_equal_for_phi_arg_p (arg1
, rhs
))
634 || (operand_equal_for_phi_arg_p (arg1
, lhs
)
635 && operand_equal_for_phi_arg_p (arg0
, rhs
)))
638 /* Now handle more complex case where we have an EQ comparison
639 which feeds a BIT_AND_EXPR which feeds COND.
641 First verify that COND is of the form SSA_NAME NE 0. */
642 if (*code
!= NE_EXPR
|| !integer_zerop (rhs
)
643 || TREE_CODE (lhs
) != SSA_NAME
)
646 /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */
647 def
= SSA_NAME_DEF_STMT (lhs
);
648 if (!is_gimple_assign (def
) || gimple_assign_rhs_code (def
) != BIT_AND_EXPR
)
651 /* Now verify arg0/arg1 correspond to the source arguments of an
652 EQ comparison feeding the BIT_AND_EXPR. */
654 tree tmp
= gimple_assign_rhs1 (def
);
655 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
658 tmp
= gimple_assign_rhs2 (def
);
659 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
665 /* Returns true if ARG is a neutral element for operation CODE
666 on the RIGHT side. */
669 neutral_element_p (tree_code code
, tree arg
, bool right
)
676 return integer_zerop (arg
);
683 case POINTER_PLUS_EXPR
:
684 return right
&& integer_zerop (arg
);
687 return integer_onep (arg
);
694 return right
&& integer_onep (arg
);
697 return integer_all_onesp (arg
);
704 /* Returns true if ARG is an absorbing element for operation CODE. */
707 absorbing_element_p (tree_code code
, tree arg
)
712 return integer_all_onesp (arg
);
716 return integer_zerop (arg
);
723 /* The function value_replacement does the main work of doing the value
724 replacement. Return non-zero if the replacement is done. Otherwise return
725 0. If we remove the middle basic block, return 2.
726 BB is the basic block where the replacement is going to be done on. ARG0
727 is argument 0 from the PHI. Likewise for ARG1. */
730 value_replacement (basic_block cond_bb
, basic_block middle_bb
,
731 edge e0
, edge e1
, gimple phi
,
732 tree arg0
, tree arg1
)
734 gimple_stmt_iterator gsi
;
736 edge true_edge
, false_edge
;
738 bool emtpy_or_with_defined_p
= true;
740 /* If the type says honor signed zeros we cannot do this
742 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
745 /* If there is a statement in MIDDLE_BB that defines one of the PHI
746 arguments, then adjust arg0 or arg1. */
747 gsi
= gsi_start_nondebug_after_labels_bb (middle_bb
);
748 while (!gsi_end_p (gsi
))
750 gimple stmt
= gsi_stmt (gsi
);
752 gsi_next_nondebug (&gsi
);
753 if (!is_gimple_assign (stmt
))
755 emtpy_or_with_defined_p
= false;
758 /* Now try to adjust arg0 or arg1 according to the computation
760 lhs
= gimple_assign_lhs (stmt
);
762 && jump_function_from_stmt (&arg0
, stmt
))
764 && jump_function_from_stmt (&arg1
, stmt
)))
765 emtpy_or_with_defined_p
= false;
768 cond
= last_stmt (cond_bb
);
769 code
= gimple_cond_code (cond
);
771 /* This transformation is only valid for equality comparisons. */
772 if (code
!= NE_EXPR
&& code
!= EQ_EXPR
)
775 /* We need to know which is the true edge and which is the false
776 edge so that we know if have abs or negative abs. */
777 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
779 /* At this point we know we have a COND_EXPR with two successors.
780 One successor is BB, the other successor is an empty block which
781 falls through into BB.
783 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
785 There is a single PHI node at the join point (BB) with two arguments.
787 We now need to verify that the two arguments in the PHI node match
788 the two arguments to the equality comparison. */
790 if (operand_equal_for_value_replacement (arg0
, arg1
, &code
, cond
))
795 /* For NE_EXPR, we want to build an assignment result = arg where
796 arg is the PHI argument associated with the true edge. For
797 EQ_EXPR we want the PHI argument associated with the false edge. */
798 e
= (code
== NE_EXPR
? true_edge
: false_edge
);
800 /* Unfortunately, E may not reach BB (it may instead have gone to
801 OTHER_BLOCK). If that is the case, then we want the single outgoing
802 edge from OTHER_BLOCK which reaches BB and represents the desired
803 path from COND_BLOCK. */
804 if (e
->dest
== middle_bb
)
805 e
= single_succ_edge (e
->dest
);
807 /* Now we know the incoming edge to BB that has the argument for the
808 RHS of our new assignment statement. */
814 /* If the middle basic block was empty or is defining the
815 PHI arguments and this is a single phi where the args are different
816 for the edges e0 and e1 then we can remove the middle basic block. */
817 if (emtpy_or_with_defined_p
818 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)),
821 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, arg
);
822 /* Note that we optimized this PHI. */
827 /* Replace the PHI arguments with arg. */
828 SET_PHI_ARG_DEF (phi
, e0
->dest_idx
, arg
);
829 SET_PHI_ARG_DEF (phi
, e1
->dest_idx
, arg
);
830 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
832 fprintf (dump_file
, "PHI ");
833 print_generic_expr (dump_file
, gimple_phi_result (phi
), 0);
834 fprintf (dump_file
, " reduced for COND_EXPR in block %d to ",
836 print_generic_expr (dump_file
, arg
, 0);
837 fprintf (dump_file
, ".\n");
844 /* Now optimize (x != 0) ? x + y : y to just y.
845 The following condition is too restrictive, there can easily be another
846 stmt in middle_bb, for instance a CONVERT_EXPR for the second argument. */
847 gimple assign
= last_and_only_stmt (middle_bb
);
848 if (!assign
|| gimple_code (assign
) != GIMPLE_ASSIGN
849 || gimple_assign_rhs_class (assign
) != GIMPLE_BINARY_RHS
850 || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
851 && !POINTER_TYPE_P (TREE_TYPE (arg0
))))
854 /* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */
855 if (!gimple_seq_empty_p (phi_nodes (middle_bb
)))
858 /* Only transform if it removes the condition. */
859 if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)), e0
, e1
))
862 /* Size-wise, this is always profitable. */
863 if (optimize_bb_for_speed_p (cond_bb
)
864 /* The special case is useless if it has a low probability. */
865 && profile_status_for_fn (cfun
) != PROFILE_ABSENT
866 && EDGE_PRED (middle_bb
, 0)->probability
< PROB_EVEN
867 /* If assign is cheap, there is no point avoiding it. */
868 && estimate_num_insns (assign
, &eni_time_weights
)
869 >= 3 * estimate_num_insns (cond
, &eni_time_weights
))
872 tree lhs
= gimple_assign_lhs (assign
);
873 tree rhs1
= gimple_assign_rhs1 (assign
);
874 tree rhs2
= gimple_assign_rhs2 (assign
);
875 enum tree_code code_def
= gimple_assign_rhs_code (assign
);
876 tree cond_lhs
= gimple_cond_lhs (cond
);
877 tree cond_rhs
= gimple_cond_rhs (cond
);
879 if (((code
== NE_EXPR
&& e1
== false_edge
)
880 || (code
== EQ_EXPR
&& e1
== true_edge
))
883 && operand_equal_for_phi_arg_p (rhs2
, cond_lhs
)
884 && neutral_element_p (code_def
, cond_rhs
, true))
886 && operand_equal_for_phi_arg_p (rhs1
, cond_lhs
)
887 && neutral_element_p (code_def
, cond_rhs
, false))
888 || (operand_equal_for_phi_arg_p (arg1
, cond_rhs
)
889 && (operand_equal_for_phi_arg_p (rhs2
, cond_lhs
)
890 || operand_equal_for_phi_arg_p (rhs1
, cond_lhs
))
891 && absorbing_element_p (code_def
, cond_rhs
))))
893 gsi
= gsi_for_stmt (cond
);
894 gimple_stmt_iterator gsi_from
= gsi_for_stmt (assign
);
895 gsi_move_before (&gsi_from
, &gsi
);
896 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, lhs
);
903 /* The function minmax_replacement does the main work of doing the minmax
904 replacement. Return true if the replacement is done. Otherwise return
906 BB is the basic block where the replacement is going to be done on. ARG0
907 is argument 0 from the PHI. Likewise for ARG1. */
910 minmax_replacement (basic_block cond_bb
, basic_block middle_bb
,
911 edge e0
, edge e1
, gimple phi
,
912 tree arg0
, tree arg1
)
916 gimple_assign new_stmt
;
917 edge true_edge
, false_edge
;
918 enum tree_code cmp
, minmax
, ass_code
;
919 tree smaller
, larger
, arg_true
, arg_false
;
920 gimple_stmt_iterator gsi
, gsi_from
;
922 type
= TREE_TYPE (PHI_RESULT (phi
));
924 /* The optimization may be unsafe due to NaNs. */
925 if (HONOR_NANS (TYPE_MODE (type
)))
928 cond
= as_a
<gimple_cond
> (last_stmt (cond_bb
));
929 cmp
= gimple_cond_code (cond
);
931 /* This transformation is only valid for order comparisons. Record which
932 operand is smaller/larger if the result of the comparison is true. */
933 if (cmp
== LT_EXPR
|| cmp
== LE_EXPR
)
935 smaller
= gimple_cond_lhs (cond
);
936 larger
= gimple_cond_rhs (cond
);
938 else if (cmp
== GT_EXPR
|| cmp
== GE_EXPR
)
940 smaller
= gimple_cond_rhs (cond
);
941 larger
= gimple_cond_lhs (cond
);
946 /* We need to know which is the true edge and which is the false
947 edge so that we know if have abs or negative abs. */
948 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
950 /* Forward the edges over the middle basic block. */
951 if (true_edge
->dest
== middle_bb
)
952 true_edge
= EDGE_SUCC (true_edge
->dest
, 0);
953 if (false_edge
->dest
== middle_bb
)
954 false_edge
= EDGE_SUCC (false_edge
->dest
, 0);
958 gcc_assert (false_edge
== e1
);
964 gcc_assert (false_edge
== e0
);
965 gcc_assert (true_edge
== e1
);
970 if (empty_block_p (middle_bb
))
972 if (operand_equal_for_phi_arg_p (arg_true
, smaller
)
973 && operand_equal_for_phi_arg_p (arg_false
, larger
))
977 if (smaller < larger)
983 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
)
984 && operand_equal_for_phi_arg_p (arg_true
, larger
))
991 /* Recognize the following case, assuming d <= u:
997 This is equivalent to
1002 gimple assign
= last_and_only_stmt (middle_bb
);
1003 tree lhs
, op0
, op1
, bound
;
1006 || gimple_code (assign
) != GIMPLE_ASSIGN
)
1009 lhs
= gimple_assign_lhs (assign
);
1010 ass_code
= gimple_assign_rhs_code (assign
);
1011 if (ass_code
!= MAX_EXPR
&& ass_code
!= MIN_EXPR
)
1013 op0
= gimple_assign_rhs1 (assign
);
1014 op1
= gimple_assign_rhs2 (assign
);
1016 if (true_edge
->src
== middle_bb
)
1018 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
1019 if (!operand_equal_for_phi_arg_p (lhs
, arg_true
))
1022 if (operand_equal_for_phi_arg_p (arg_false
, larger
))
1026 if (smaller < larger)
1028 r' = MAX_EXPR (smaller, bound)
1030 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
1031 if (ass_code
!= MAX_EXPR
)
1035 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1037 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1042 /* We need BOUND <= LARGER. */
1043 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1047 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
))
1051 if (smaller < larger)
1053 r' = MIN_EXPR (larger, bound)
1055 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
1056 if (ass_code
!= MIN_EXPR
)
1060 if (operand_equal_for_phi_arg_p (op0
, larger
))
1062 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1067 /* We need BOUND >= SMALLER. */
1068 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1077 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
1078 if (!operand_equal_for_phi_arg_p (lhs
, arg_false
))
1081 if (operand_equal_for_phi_arg_p (arg_true
, larger
))
1085 if (smaller > larger)
1087 r' = MIN_EXPR (smaller, bound)
1089 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
1090 if (ass_code
!= MIN_EXPR
)
1094 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1096 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1101 /* We need BOUND >= LARGER. */
1102 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1106 else if (operand_equal_for_phi_arg_p (arg_true
, smaller
))
1110 if (smaller > larger)
1112 r' = MAX_EXPR (larger, bound)
1114 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
1115 if (ass_code
!= MAX_EXPR
)
1119 if (operand_equal_for_phi_arg_p (op0
, larger
))
1121 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1126 /* We need BOUND <= SMALLER. */
1127 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1135 /* Move the statement from the middle block. */
1136 gsi
= gsi_last_bb (cond_bb
);
1137 gsi_from
= gsi_last_nondebug_bb (middle_bb
);
1138 gsi_move_before (&gsi_from
, &gsi
);
1141 /* Emit the statement to compute min/max. */
1142 result
= duplicate_ssa_name (PHI_RESULT (phi
), NULL
);
1143 new_stmt
= gimple_build_assign_with_ops (minmax
, result
, arg0
, arg1
);
1144 gsi
= gsi_last_bb (cond_bb
);
1145 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1147 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1151 /* The function absolute_replacement does the main work of doing the absolute
1152 replacement. Return true if the replacement is done. Otherwise return
1154 bb is the basic block where the replacement is going to be done on. arg0
1155 is argument 0 from the phi. Likewise for arg1. */
1158 abs_replacement (basic_block cond_bb
, basic_block middle_bb
,
1159 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1160 gimple phi
, tree arg0
, tree arg1
)
1163 gimple_assign new_stmt
;
1165 gimple_stmt_iterator gsi
;
1166 edge true_edge
, false_edge
;
1171 enum tree_code cond_code
;
1173 /* If the type says honor signed zeros we cannot do this
1175 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1
))))
1178 /* OTHER_BLOCK must have only one executable statement which must have the
1179 form arg0 = -arg1 or arg1 = -arg0. */
1181 assign
= last_and_only_stmt (middle_bb
);
1182 /* If we did not find the proper negation assignment, then we can not
1187 /* If we got here, then we have found the only executable statement
1188 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1189 arg1 = -arg0, then we can not optimize. */
1190 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1193 lhs
= gimple_assign_lhs (assign
);
1195 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1198 rhs
= gimple_assign_rhs1 (assign
);
1200 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1201 if (!(lhs
== arg0
&& rhs
== arg1
)
1202 && !(lhs
== arg1
&& rhs
== arg0
))
1205 cond
= last_stmt (cond_bb
);
1206 result
= PHI_RESULT (phi
);
1208 /* Only relationals comparing arg[01] against zero are interesting. */
1209 cond_code
= gimple_cond_code (cond
);
1210 if (cond_code
!= GT_EXPR
&& cond_code
!= GE_EXPR
1211 && cond_code
!= LT_EXPR
&& cond_code
!= LE_EXPR
)
1214 /* Make sure the conditional is arg[01] OP y. */
1215 if (gimple_cond_lhs (cond
) != rhs
)
1218 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond
)))
1219 ? real_zerop (gimple_cond_rhs (cond
))
1220 : integer_zerop (gimple_cond_rhs (cond
)))
1225 /* We need to know which is the true edge and which is the false
1226 edge so that we know if have abs or negative abs. */
1227 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1229 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1230 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1231 the false edge goes to OTHER_BLOCK. */
1232 if (cond_code
== GT_EXPR
|| cond_code
== GE_EXPR
)
1237 if (e
->dest
== middle_bb
)
1242 result
= duplicate_ssa_name (result
, NULL
);
1245 lhs
= make_ssa_name (TREE_TYPE (result
), NULL
);
1249 /* Build the modify expression with abs expression. */
1250 new_stmt
= gimple_build_assign_with_ops (ABS_EXPR
, lhs
, rhs
, NULL
);
1252 gsi
= gsi_last_bb (cond_bb
);
1253 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1257 /* Get the right GSI. We want to insert after the recently
1258 added ABS_EXPR statement (which we know is the first statement
1260 new_stmt
= gimple_build_assign_with_ops (NEGATE_EXPR
, result
, lhs
, NULL
);
1262 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1265 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1267 /* Note that we optimized this PHI. */
1271 /* The function neg_replacement replaces conditional negation with
1272 equivalent straight line code. Returns TRUE if replacement is done,
1273 otherwise returns FALSE.
1275 COND_BB branches around negation occuring in MIDDLE_BB.
1277 E0 and E1 are edges out of COND_BB. E0 reaches MIDDLE_BB and
1278 E1 reaches the other successor which should contain PHI with
1279 arguments ARG0 and ARG1.
1281 Assuming negation is to occur when the condition is true,
1282 then the non-branching sequence is:
1284 result = (rhs ^ -cond) + cond
1286 Inverting the condition or its result gives us negation
1287 when the original condition is false. */
1290 neg_replacement (basic_block cond_bb
, basic_block middle_bb
,
1291 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1292 gimple phi
, tree arg0
, tree arg1
)
1294 gimple new_stmt
, cond
;
1295 gimple_stmt_iterator gsi
;
1297 edge true_edge
, false_edge
;
1299 enum tree_code cond_code
;
1300 bool invert
= false;
1302 /* This transformation performs logical operations on the
1303 incoming arguments. So force them to be integral types. */
1304 if (!INTEGRAL_TYPE_P (TREE_TYPE (arg0
)))
1307 /* OTHER_BLOCK must have only one executable statement which must have the
1308 form arg0 = -arg1 or arg1 = -arg0. */
1310 assign
= last_and_only_stmt (middle_bb
);
1311 /* If we did not find the proper negation assignment, then we can not
1316 /* If we got here, then we have found the only executable statement
1317 in OTHER_BLOCK. If it is anything other than arg0 = -arg1 or
1318 arg1 = -arg0, then we can not optimize. */
1319 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1322 lhs
= gimple_assign_lhs (assign
);
1324 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1327 rhs
= gimple_assign_rhs1 (assign
);
1329 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1330 if (!(lhs
== arg0
&& rhs
== arg1
)
1331 && !(lhs
== arg1
&& rhs
== arg0
))
1334 /* The basic sequence assumes we negate when the condition is true.
1335 If we need the opposite, then we will either need to invert the
1336 condition or its result. */
1337 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1338 invert
= false_edge
->dest
== middle_bb
;
1340 /* Unlike abs_replacement, we can handle arbitrary conditionals here. */
1341 cond
= last_stmt (cond_bb
);
1342 cond_code
= gimple_cond_code (cond
);
1344 /* If inversion is needed, first try to invert the test since
1349 = HONOR_NANS (TYPE_MODE (TREE_TYPE (gimple_cond_lhs (cond
))));
1350 enum tree_code new_code
= invert_tree_comparison (cond_code
, honor_nans
);
1352 /* If invert_tree_comparison was successful, then use its return
1353 value as the new code and note that inversion is no longer
1355 if (new_code
!= ERROR_MARK
)
1357 cond_code
= new_code
;
1362 tree cond_val
= make_ssa_name (boolean_type_node
, NULL
);
1363 new_stmt
= gimple_build_assign_with_ops (cond_code
, cond_val
,
1364 gimple_cond_lhs (cond
),
1365 gimple_cond_rhs (cond
));
1366 gsi
= gsi_last_bb (cond_bb
);
1367 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1369 /* If we still need inversion, then invert the result of the
1373 tree tmp
= make_ssa_name (boolean_type_node
, NULL
);
1374 new_stmt
= gimple_build_assign_with_ops (BIT_XOR_EXPR
, tmp
,
1375 cond_val
, boolean_true_node
);
1376 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1380 /* Get the condition in the right type so that we can perform
1381 logical and arithmetic operations on it. */
1382 tree cond_val_converted
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1383 new_stmt
= gimple_build_assign_with_ops (NOP_EXPR
, cond_val_converted
,
1384 cond_val
, NULL_TREE
);
1385 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1387 tree neg_cond_val_converted
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1388 new_stmt
= gimple_build_assign_with_ops (NEGATE_EXPR
, neg_cond_val_converted
,
1389 cond_val_converted
, NULL_TREE
);
1390 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1392 tree tmp
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1393 new_stmt
= gimple_build_assign_with_ops (BIT_XOR_EXPR
, tmp
,
1394 rhs
, neg_cond_val_converted
);
1395 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1397 tree new_lhs
= make_ssa_name (TREE_TYPE (rhs
), NULL
);
1398 new_stmt
= gimple_build_assign_with_ops (PLUS_EXPR
, new_lhs
,
1399 tmp
, cond_val_converted
);
1400 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1402 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_lhs
);
1404 /* Note that we optimized this PHI. */
1408 /* Auxiliary functions to determine the set of memory accesses which
1409 can't trap because they are preceded by accesses to the same memory
1410 portion. We do that for MEM_REFs, so we only need to track
1411 the SSA_NAME of the pointer indirectly referenced. The algorithm
1412 simply is a walk over all instructions in dominator order. When
1413 we see an MEM_REF we determine if we've already seen a same
1414 ref anywhere up to the root of the dominator tree. If we do the
1415 current access can't trap. If we don't see any dominating access
1416 the current access might trap, but might also make later accesses
1417 non-trapping, so we remember it. We need to be careful with loads
1418 or stores, for instance a load might not trap, while a store would,
1419 so if we see a dominating read access this doesn't mean that a later
1420 write access would not trap. Hence we also need to differentiate the
1421 type of access(es) seen.
1423 ??? We currently are very conservative and assume that a load might
1424 trap even if a store doesn't (write-only memory). This probably is
1425 overly conservative. */
1427 /* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1428 through it was seen, which would constitute a no-trap region for
1432 unsigned int ssa_name_ver
;
1435 HOST_WIDE_INT offset
, size
;
1439 /* Hashtable helpers. */
1441 struct ssa_names_hasher
: typed_free_remove
<name_to_bb
>
1443 typedef name_to_bb value_type
;
1444 typedef name_to_bb compare_type
;
1445 static inline hashval_t
hash (const value_type
*);
1446 static inline bool equal (const value_type
*, const compare_type
*);
1449 /* Used for quick clearing of the hash-table when we see calls.
1450 Hash entries with phase < nt_call_phase are invalid. */
1451 static unsigned int nt_call_phase
;
1453 /* The hash function. */
1456 ssa_names_hasher::hash (const value_type
*n
)
1458 return n
->ssa_name_ver
^ (((hashval_t
) n
->store
) << 31)
1459 ^ (n
->offset
<< 6) ^ (n
->size
<< 3);
1462 /* The equality function of *P1 and *P2. */
1465 ssa_names_hasher::equal (const value_type
*n1
, const compare_type
*n2
)
1467 return n1
->ssa_name_ver
== n2
->ssa_name_ver
1468 && n1
->store
== n2
->store
1469 && n1
->offset
== n2
->offset
1470 && n1
->size
== n2
->size
;
1473 class nontrapping_dom_walker
: public dom_walker
1476 nontrapping_dom_walker (cdi_direction direction
, hash_set
<tree
> *ps
)
1477 : dom_walker (direction
), m_nontrapping (ps
), m_seen_ssa_names (128) {}
1479 virtual void before_dom_children (basic_block
);
1480 virtual void after_dom_children (basic_block
);
1484 /* We see the expression EXP in basic block BB. If it's an interesting
1485 expression (an MEM_REF through an SSA_NAME) possibly insert the
1486 expression into the set NONTRAP or the hash table of seen expressions.
1487 STORE is true if this expression is on the LHS, otherwise it's on
1489 void add_or_mark_expr (basic_block
, tree
, bool);
1491 hash_set
<tree
> *m_nontrapping
;
1493 /* The hash table for remembering what we've seen. */
1494 hash_table
<ssa_names_hasher
> m_seen_ssa_names
;
1497 /* Called by walk_dominator_tree, when entering the block BB. */
1499 nontrapping_dom_walker::before_dom_children (basic_block bb
)
1503 gimple_stmt_iterator gsi
;
1505 /* If we haven't seen all our predecessors, clear the hash-table. */
1506 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1507 if ((((size_t)e
->src
->aux
) & 2) == 0)
1513 /* Mark this BB as being on the path to dominator root and as visited. */
1514 bb
->aux
= (void*)(1 | 2);
1516 /* And walk the statements in order. */
1517 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1519 gimple stmt
= gsi_stmt (gsi
);
1521 if (is_gimple_call (stmt
) && !nonfreeing_call_p (stmt
))
1523 else if (gimple_assign_single_p (stmt
) && !gimple_has_volatile_ops (stmt
))
1525 add_or_mark_expr (bb
, gimple_assign_lhs (stmt
), true);
1526 add_or_mark_expr (bb
, gimple_assign_rhs1 (stmt
), false);
1531 /* Called by walk_dominator_tree, when basic block BB is exited. */
1533 nontrapping_dom_walker::after_dom_children (basic_block bb
)
1535 /* This BB isn't on the path to dominator root anymore. */
1539 /* We see the expression EXP in basic block BB. If it's an interesting
1540 expression (an MEM_REF through an SSA_NAME) possibly insert the
1541 expression into the set NONTRAP or the hash table of seen expressions.
1542 STORE is true if this expression is on the LHS, otherwise it's on
1545 nontrapping_dom_walker::add_or_mark_expr (basic_block bb
, tree exp
, bool store
)
1549 if (TREE_CODE (exp
) == MEM_REF
1550 && TREE_CODE (TREE_OPERAND (exp
, 0)) == SSA_NAME
1551 && tree_fits_shwi_p (TREE_OPERAND (exp
, 1))
1552 && (size
= int_size_in_bytes (TREE_TYPE (exp
))) > 0)
1554 tree name
= TREE_OPERAND (exp
, 0);
1555 struct name_to_bb map
;
1557 struct name_to_bb
*n2bb
;
1558 basic_block found_bb
= 0;
1560 /* Try to find the last seen MEM_REF through the same
1561 SSA_NAME, which can trap. */
1562 map
.ssa_name_ver
= SSA_NAME_VERSION (name
);
1566 map
.offset
= tree_to_shwi (TREE_OPERAND (exp
, 1));
1569 slot
= m_seen_ssa_names
.find_slot (&map
, INSERT
);
1571 if (n2bb
&& n2bb
->phase
>= nt_call_phase
)
1572 found_bb
= n2bb
->bb
;
1574 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1575 (it's in a basic block on the path from us to the dominator root)
1576 then we can't trap. */
1577 if (found_bb
&& (((size_t)found_bb
->aux
) & 1) == 1)
1579 m_nontrapping
->add (exp
);
1583 /* EXP might trap, so insert it into the hash table. */
1586 n2bb
->phase
= nt_call_phase
;
1591 n2bb
= XNEW (struct name_to_bb
);
1592 n2bb
->ssa_name_ver
= SSA_NAME_VERSION (name
);
1593 n2bb
->phase
= nt_call_phase
;
1595 n2bb
->store
= store
;
1596 n2bb
->offset
= map
.offset
;
1604 /* This is the entry point of gathering non trapping memory accesses.
1605 It will do a dominator walk over the whole function, and it will
1606 make use of the bb->aux pointers. It returns a set of trees
1607 (the MEM_REFs itself) which can't trap. */
1608 static hash_set
<tree
> *
1609 get_non_trapping (void)
1612 hash_set
<tree
> *nontrap
= new hash_set
<tree
>;
1613 /* We're going to do a dominator walk, so ensure that we have
1614 dominance information. */
1615 calculate_dominance_info (CDI_DOMINATORS
);
1617 nontrapping_dom_walker (CDI_DOMINATORS
, nontrap
)
1618 .walk (cfun
->cfg
->x_entry_block_ptr
);
1620 clear_aux_for_blocks ();
1624 /* Do the main work of conditional store replacement. We already know
1625 that the recognized pattern looks like so:
1628 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1631 fallthrough (edge E0)
1635 We check that MIDDLE_BB contains only one store, that that store
1636 doesn't trap (not via NOTRAP, but via checking if an access to the same
1637 memory location dominates us) and that the store has a "simple" RHS. */
1640 cond_store_replacement (basic_block middle_bb
, basic_block join_bb
,
1641 edge e0
, edge e1
, hash_set
<tree
> *nontrap
)
1643 gimple assign
= last_and_only_stmt (middle_bb
);
1644 tree lhs
, rhs
, name
, name2
;
1646 gimple_assign new_stmt
;
1647 gimple_stmt_iterator gsi
;
1648 source_location locus
;
1650 /* Check if middle_bb contains of only one store. */
1652 || !gimple_assign_single_p (assign
)
1653 || gimple_has_volatile_ops (assign
))
1656 locus
= gimple_location (assign
);
1657 lhs
= gimple_assign_lhs (assign
);
1658 rhs
= gimple_assign_rhs1 (assign
);
1659 if (TREE_CODE (lhs
) != MEM_REF
1660 || TREE_CODE (TREE_OPERAND (lhs
, 0)) != SSA_NAME
1661 || !is_gimple_reg_type (TREE_TYPE (lhs
)))
1664 /* Prove that we can move the store down. We could also check
1665 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1666 whose value is not available readily, which we want to avoid. */
1667 if (!nontrap
->contains (lhs
))
1670 /* Now we've checked the constraints, so do the transformation:
1671 1) Remove the single store. */
1672 gsi
= gsi_for_stmt (assign
);
1673 unlink_stmt_vdef (assign
);
1674 gsi_remove (&gsi
, true);
1675 release_defs (assign
);
1677 /* 2) Insert a load from the memory of the store to the temporary
1678 on the edge which did not contain the store. */
1679 lhs
= unshare_expr (lhs
);
1680 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1681 new_stmt
= gimple_build_assign (name
, lhs
);
1682 gimple_set_location (new_stmt
, locus
);
1683 gsi_insert_on_edge (e1
, new_stmt
);
1685 /* 3) Create a PHI node at the join block, with one argument
1686 holding the old RHS, and the other holding the temporary
1687 where we stored the old memory contents. */
1688 name2
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1689 newphi
= create_phi_node (name2
, join_bb
);
1690 add_phi_arg (newphi
, rhs
, e0
, locus
);
1691 add_phi_arg (newphi
, name
, e1
, locus
);
1693 lhs
= unshare_expr (lhs
);
1694 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1696 /* 4) Insert that PHI node. */
1697 gsi
= gsi_after_labels (join_bb
);
1698 if (gsi_end_p (gsi
))
1700 gsi
= gsi_last_bb (join_bb
);
1701 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1704 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1709 /* Do the main work of conditional store replacement. */
1712 cond_if_else_store_replacement_1 (basic_block then_bb
, basic_block else_bb
,
1713 basic_block join_bb
, gimple then_assign
,
1716 tree lhs_base
, lhs
, then_rhs
, else_rhs
, name
;
1717 source_location then_locus
, else_locus
;
1718 gimple_stmt_iterator gsi
;
1720 gimple_assign new_stmt
;
1722 if (then_assign
== NULL
1723 || !gimple_assign_single_p (then_assign
)
1724 || gimple_clobber_p (then_assign
)
1725 || gimple_has_volatile_ops (then_assign
)
1726 || else_assign
== NULL
1727 || !gimple_assign_single_p (else_assign
)
1728 || gimple_clobber_p (else_assign
)
1729 || gimple_has_volatile_ops (else_assign
))
1732 lhs
= gimple_assign_lhs (then_assign
);
1733 if (!is_gimple_reg_type (TREE_TYPE (lhs
))
1734 || !operand_equal_p (lhs
, gimple_assign_lhs (else_assign
), 0))
1737 lhs_base
= get_base_address (lhs
);
1738 if (lhs_base
== NULL_TREE
1739 || (!DECL_P (lhs_base
) && TREE_CODE (lhs_base
) != MEM_REF
))
1742 then_rhs
= gimple_assign_rhs1 (then_assign
);
1743 else_rhs
= gimple_assign_rhs1 (else_assign
);
1744 then_locus
= gimple_location (then_assign
);
1745 else_locus
= gimple_location (else_assign
);
1747 /* Now we've checked the constraints, so do the transformation:
1748 1) Remove the stores. */
1749 gsi
= gsi_for_stmt (then_assign
);
1750 unlink_stmt_vdef (then_assign
);
1751 gsi_remove (&gsi
, true);
1752 release_defs (then_assign
);
1754 gsi
= gsi_for_stmt (else_assign
);
1755 unlink_stmt_vdef (else_assign
);
1756 gsi_remove (&gsi
, true);
1757 release_defs (else_assign
);
1759 /* 2) Create a PHI node at the join block, with one argument
1760 holding the old RHS, and the other holding the temporary
1761 where we stored the old memory contents. */
1762 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1763 newphi
= create_phi_node (name
, join_bb
);
1764 add_phi_arg (newphi
, then_rhs
, EDGE_SUCC (then_bb
, 0), then_locus
);
1765 add_phi_arg (newphi
, else_rhs
, EDGE_SUCC (else_bb
, 0), else_locus
);
1767 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1769 /* 3) Insert that PHI node. */
1770 gsi
= gsi_after_labels (join_bb
);
1771 if (gsi_end_p (gsi
))
1773 gsi
= gsi_last_bb (join_bb
);
1774 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1777 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1782 /* Conditional store replacement. We already know
1783 that the recognized pattern looks like so:
1786 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
1796 fallthrough (edge E0)
1800 We check that it is safe to sink the store to JOIN_BB by verifying that
1801 there are no read-after-write or write-after-write dependencies in
1802 THEN_BB and ELSE_BB. */
1805 cond_if_else_store_replacement (basic_block then_bb
, basic_block else_bb
,
1806 basic_block join_bb
)
1808 gimple then_assign
= last_and_only_stmt (then_bb
);
1809 gimple else_assign
= last_and_only_stmt (else_bb
);
1810 vec
<data_reference_p
> then_datarefs
, else_datarefs
;
1811 vec
<ddr_p
> then_ddrs
, else_ddrs
;
1812 gimple then_store
, else_store
;
1813 bool found
, ok
= false, res
;
1814 struct data_dependence_relation
*ddr
;
1815 data_reference_p then_dr
, else_dr
;
1817 tree then_lhs
, else_lhs
;
1818 basic_block blocks
[3];
1820 if (MAX_STORES_TO_SINK
== 0)
1823 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
1824 if (then_assign
&& else_assign
)
1825 return cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1826 then_assign
, else_assign
);
1828 /* Find data references. */
1829 then_datarefs
.create (1);
1830 else_datarefs
.create (1);
1831 if ((find_data_references_in_bb (NULL
, then_bb
, &then_datarefs
)
1833 || !then_datarefs
.length ()
1834 || (find_data_references_in_bb (NULL
, else_bb
, &else_datarefs
)
1836 || !else_datarefs
.length ())
1838 free_data_refs (then_datarefs
);
1839 free_data_refs (else_datarefs
);
1843 /* Find pairs of stores with equal LHS. */
1844 auto_vec
<gimple
, 1> then_stores
, else_stores
;
1845 FOR_EACH_VEC_ELT (then_datarefs
, i
, then_dr
)
1847 if (DR_IS_READ (then_dr
))
1850 then_store
= DR_STMT (then_dr
);
1851 then_lhs
= gimple_get_lhs (then_store
);
1852 if (then_lhs
== NULL_TREE
)
1856 FOR_EACH_VEC_ELT (else_datarefs
, j
, else_dr
)
1858 if (DR_IS_READ (else_dr
))
1861 else_store
= DR_STMT (else_dr
);
1862 else_lhs
= gimple_get_lhs (else_store
);
1863 if (else_lhs
== NULL_TREE
)
1866 if (operand_equal_p (then_lhs
, else_lhs
, 0))
1876 then_stores
.safe_push (then_store
);
1877 else_stores
.safe_push (else_store
);
1880 /* No pairs of stores found. */
1881 if (!then_stores
.length ()
1882 || then_stores
.length () > (unsigned) MAX_STORES_TO_SINK
)
1884 free_data_refs (then_datarefs
);
1885 free_data_refs (else_datarefs
);
1889 /* Compute and check data dependencies in both basic blocks. */
1890 then_ddrs
.create (1);
1891 else_ddrs
.create (1);
1892 if (!compute_all_dependences (then_datarefs
, &then_ddrs
,
1894 || !compute_all_dependences (else_datarefs
, &else_ddrs
,
1897 free_dependence_relations (then_ddrs
);
1898 free_dependence_relations (else_ddrs
);
1899 free_data_refs (then_datarefs
);
1900 free_data_refs (else_datarefs
);
1903 blocks
[0] = then_bb
;
1904 blocks
[1] = else_bb
;
1905 blocks
[2] = join_bb
;
1906 renumber_gimple_stmt_uids_in_blocks (blocks
, 3);
1908 /* Check that there are no read-after-write or write-after-write dependencies
1910 FOR_EACH_VEC_ELT (then_ddrs
, i
, ddr
)
1912 struct data_reference
*dra
= DDR_A (ddr
);
1913 struct data_reference
*drb
= DDR_B (ddr
);
1915 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1916 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1917 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1918 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1919 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1920 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1922 free_dependence_relations (then_ddrs
);
1923 free_dependence_relations (else_ddrs
);
1924 free_data_refs (then_datarefs
);
1925 free_data_refs (else_datarefs
);
1930 /* Check that there are no read-after-write or write-after-write dependencies
1932 FOR_EACH_VEC_ELT (else_ddrs
, i
, ddr
)
1934 struct data_reference
*dra
= DDR_A (ddr
);
1935 struct data_reference
*drb
= DDR_B (ddr
);
1937 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1938 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1939 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1940 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1941 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1942 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1944 free_dependence_relations (then_ddrs
);
1945 free_dependence_relations (else_ddrs
);
1946 free_data_refs (then_datarefs
);
1947 free_data_refs (else_datarefs
);
1952 /* Sink stores with same LHS. */
1953 FOR_EACH_VEC_ELT (then_stores
, i
, then_store
)
1955 else_store
= else_stores
[i
];
1956 res
= cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1957 then_store
, else_store
);
1961 free_dependence_relations (then_ddrs
);
1962 free_dependence_relations (else_ddrs
);
1963 free_data_refs (then_datarefs
);
1964 free_data_refs (else_datarefs
);
1969 /* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
1972 local_mem_dependence (gimple stmt
, basic_block bb
)
1974 tree vuse
= gimple_vuse (stmt
);
1980 def
= SSA_NAME_DEF_STMT (vuse
);
1981 return (def
&& gimple_bb (def
) == bb
);
1984 /* Given a "diamond" control-flow pattern where BB0 tests a condition,
1985 BB1 and BB2 are "then" and "else" blocks dependent on this test,
1986 and BB3 rejoins control flow following BB1 and BB2, look for
1987 opportunities to hoist loads as follows. If BB3 contains a PHI of
1988 two loads, one each occurring in BB1 and BB2, and the loads are
1989 provably of adjacent fields in the same structure, then move both
1990 loads into BB0. Of course this can only be done if there are no
1991 dependencies preventing such motion.
1993 One of the hoisted loads will always be speculative, so the
1994 transformation is currently conservative:
1996 - The fields must be strictly adjacent.
1997 - The two fields must occupy a single memory block that is
1998 guaranteed to not cross a page boundary.
2000 The last is difficult to prove, as such memory blocks should be
2001 aligned on the minimum of the stack alignment boundary and the
2002 alignment guaranteed by heap allocation interfaces. Thus we rely
2003 on a parameter for the alignment value.
2005 Provided a good value is used for the last case, the first
2006 restriction could possibly be relaxed. */
2009 hoist_adjacent_loads (basic_block bb0
, basic_block bb1
,
2010 basic_block bb2
, basic_block bb3
)
2012 int param_align
= PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
);
2013 unsigned param_align_bits
= (unsigned) (param_align
* BITS_PER_UNIT
);
2014 gimple_phi_iterator gsi
;
2016 /* Walk the phis in bb3 looking for an opportunity. We are looking
2017 for phis of two SSA names, one each of which is defined in bb1 and
2019 for (gsi
= gsi_start_phis (bb3
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2021 gimple_phi phi_stmt
= gsi
.phi ();
2022 gimple def1
, def2
, defswap
;
2023 tree arg1
, arg2
, ref1
, ref2
, field1
, field2
, fieldswap
;
2024 tree tree_offset1
, tree_offset2
, tree_size2
, next
;
2025 int offset1
, offset2
, size2
;
2027 gimple_stmt_iterator gsi2
;
2028 basic_block bb_for_def1
, bb_for_def2
;
2030 if (gimple_phi_num_args (phi_stmt
) != 2
2031 || virtual_operand_p (gimple_phi_result (phi_stmt
)))
2034 arg1
= gimple_phi_arg_def (phi_stmt
, 0);
2035 arg2
= gimple_phi_arg_def (phi_stmt
, 1);
2037 if (TREE_CODE (arg1
) != SSA_NAME
2038 || TREE_CODE (arg2
) != SSA_NAME
2039 || SSA_NAME_IS_DEFAULT_DEF (arg1
)
2040 || SSA_NAME_IS_DEFAULT_DEF (arg2
))
2043 def1
= SSA_NAME_DEF_STMT (arg1
);
2044 def2
= SSA_NAME_DEF_STMT (arg2
);
2046 if ((gimple_bb (def1
) != bb1
|| gimple_bb (def2
) != bb2
)
2047 && (gimple_bb (def2
) != bb1
|| gimple_bb (def1
) != bb2
))
2050 /* Check the mode of the arguments to be sure a conditional move
2051 can be generated for it. */
2052 if (optab_handler (movcc_optab
, TYPE_MODE (TREE_TYPE (arg1
)))
2053 == CODE_FOR_nothing
)
2056 /* Both statements must be assignments whose RHS is a COMPONENT_REF. */
2057 if (!gimple_assign_single_p (def1
)
2058 || !gimple_assign_single_p (def2
)
2059 || gimple_has_volatile_ops (def1
)
2060 || gimple_has_volatile_ops (def2
))
2063 ref1
= gimple_assign_rhs1 (def1
);
2064 ref2
= gimple_assign_rhs1 (def2
);
2066 if (TREE_CODE (ref1
) != COMPONENT_REF
2067 || TREE_CODE (ref2
) != COMPONENT_REF
)
2070 /* The zeroth operand of the two component references must be
2071 identical. It is not sufficient to compare get_base_address of
2072 the two references, because this could allow for different
2073 elements of the same array in the two trees. It is not safe to
2074 assume that the existence of one array element implies the
2075 existence of a different one. */
2076 if (!operand_equal_p (TREE_OPERAND (ref1
, 0), TREE_OPERAND (ref2
, 0), 0))
2079 field1
= TREE_OPERAND (ref1
, 1);
2080 field2
= TREE_OPERAND (ref2
, 1);
2082 /* Check for field adjacency, and ensure field1 comes first. */
2083 for (next
= DECL_CHAIN (field1
);
2084 next
&& TREE_CODE (next
) != FIELD_DECL
;
2085 next
= DECL_CHAIN (next
))
2090 for (next
= DECL_CHAIN (field2
);
2091 next
&& TREE_CODE (next
) != FIELD_DECL
;
2092 next
= DECL_CHAIN (next
))
2106 bb_for_def1
= gimple_bb (def1
);
2107 bb_for_def2
= gimple_bb (def2
);
2109 /* Check for proper alignment of the first field. */
2110 tree_offset1
= bit_position (field1
);
2111 tree_offset2
= bit_position (field2
);
2112 tree_size2
= DECL_SIZE (field2
);
2114 if (!tree_fits_uhwi_p (tree_offset1
)
2115 || !tree_fits_uhwi_p (tree_offset2
)
2116 || !tree_fits_uhwi_p (tree_size2
))
2119 offset1
= tree_to_uhwi (tree_offset1
);
2120 offset2
= tree_to_uhwi (tree_offset2
);
2121 size2
= tree_to_uhwi (tree_size2
);
2122 align1
= DECL_ALIGN (field1
) % param_align_bits
;
2124 if (offset1
% BITS_PER_UNIT
!= 0)
2127 /* For profitability, the two field references should fit within
2128 a single cache line. */
2129 if (align1
+ offset2
- offset1
+ size2
> param_align_bits
)
2132 /* The two expressions cannot be dependent upon vdefs defined
2134 if (local_mem_dependence (def1
, bb_for_def1
)
2135 || local_mem_dependence (def2
, bb_for_def2
))
2138 /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
2139 bb0. We hoist the first one first so that a cache miss is handled
2140 efficiently regardless of hardware cache-fill policy. */
2141 gsi2
= gsi_for_stmt (def1
);
2142 gsi_move_to_bb_end (&gsi2
, bb0
);
2143 gsi2
= gsi_for_stmt (def2
);
2144 gsi_move_to_bb_end (&gsi2
, bb0
);
2146 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2149 "\nHoisting adjacent loads from %d and %d into %d: \n",
2150 bb_for_def1
->index
, bb_for_def2
->index
, bb0
->index
);
2151 print_gimple_stmt (dump_file
, def1
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2152 print_gimple_stmt (dump_file
, def2
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2157 /* Determine whether we should attempt to hoist adjacent loads out of
2158 diamond patterns in pass_phiopt. Always hoist loads if
2159 -fhoist-adjacent-loads is specified and the target machine has
2160 both a conditional move instruction and a defined cache line size. */
2163 gate_hoist_loads (void)
2165 return (flag_hoist_adjacent_loads
== 1
2166 && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
)
2167 && HAVE_conditional_move
);
2170 /* This pass tries to replaces an if-then-else block with an
2171 assignment. We have four kinds of transformations. Some of these
2172 transformations are also performed by the ifcvt RTL optimizer.
2174 Conditional Replacement
2175 -----------------------
2177 This transformation, implemented in conditional_replacement,
2181 if (cond) goto bb2; else goto bb1;
2184 x = PHI <0 (bb1), 1 (bb0), ...>;
2192 x = PHI <x' (bb0), ...>;
2194 We remove bb1 as it becomes unreachable. This occurs often due to
2195 gimplification of conditionals.
2200 This transformation, implemented in value_replacement, replaces
2203 if (a != b) goto bb2; else goto bb1;
2206 x = PHI <a (bb1), b (bb0), ...>;
2212 x = PHI <b (bb0), ...>;
2214 This opportunity can sometimes occur as a result of other
2218 Another case caught by value replacement looks like this:
2224 if (t3 != 0) goto bb1; else goto bb2;
2240 This transformation, implemented in abs_replacement, replaces
2243 if (a >= 0) goto bb2; else goto bb1;
2247 x = PHI <x (bb1), a (bb0), ...>;
2254 x = PHI <x' (bb0), ...>;
2259 This transformation, minmax_replacement replaces
2262 if (a <= b) goto bb2; else goto bb1;
2265 x = PHI <b (bb1), a (bb0), ...>;
2270 x' = MIN_EXPR (a, b)
2272 x = PHI <x' (bb0), ...>;
2274 A similar transformation is done for MAX_EXPR.
2277 This pass also performs a fifth transformation of a slightly different
2280 Adjacent Load Hoisting
2281 ----------------------
2283 This transformation replaces
2286 if (...) goto bb2; else goto bb1;
2288 x1 = (<expr>).field1;
2291 x2 = (<expr>).field2;
2298 x1 = (<expr>).field1;
2299 x2 = (<expr>).field2;
2300 if (...) goto bb2; else goto bb1;
2307 The purpose of this transformation is to enable generation of conditional
2308 move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
2309 the loads is speculative, the transformation is restricted to very
2310 specific cases to avoid introducing a page fault. We are looking for
2318 where left and right are typically adjacent pointers in a tree structure. */
2322 const pass_data pass_data_phiopt
=
2324 GIMPLE_PASS
, /* type */
2325 "phiopt", /* name */
2326 OPTGROUP_NONE
, /* optinfo_flags */
2327 TV_TREE_PHIOPT
, /* tv_id */
2328 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2329 0, /* properties_provided */
2330 0, /* properties_destroyed */
2331 0, /* todo_flags_start */
2332 0, /* todo_flags_finish */
2335 class pass_phiopt
: public gimple_opt_pass
2338 pass_phiopt (gcc::context
*ctxt
)
2339 : gimple_opt_pass (pass_data_phiopt
, ctxt
)
2342 /* opt_pass methods: */
2343 opt_pass
* clone () { return new pass_phiopt (m_ctxt
); }
2344 virtual bool gate (function
*) { return flag_ssa_phiopt
; }
2345 virtual unsigned int execute (function
*)
2347 return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
2350 }; // class pass_phiopt
2355 make_pass_phiopt (gcc::context
*ctxt
)
2357 return new pass_phiopt (ctxt
);
2362 const pass_data pass_data_cselim
=
2364 GIMPLE_PASS
, /* type */
2365 "cselim", /* name */
2366 OPTGROUP_NONE
, /* optinfo_flags */
2367 TV_TREE_PHIOPT
, /* tv_id */
2368 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2369 0, /* properties_provided */
2370 0, /* properties_destroyed */
2371 0, /* todo_flags_start */
2372 0, /* todo_flags_finish */
2375 class pass_cselim
: public gimple_opt_pass
2378 pass_cselim (gcc::context
*ctxt
)
2379 : gimple_opt_pass (pass_data_cselim
, ctxt
)
2382 /* opt_pass methods: */
2383 virtual bool gate (function
*) { return flag_tree_cselim
; }
2384 virtual unsigned int execute (function
*) { return tree_ssa_cs_elim (); }
2386 }; // class pass_cselim
2391 make_pass_cselim (gcc::context
*ctxt
)
2393 return new pass_cselim (ctxt
);