1 /* Optimization of PHI nodes by converting them into straightline code.
2 Copyright (C) 2004-2015 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"
29 #include "fold-const.h"
30 #include "stor-layout.h"
34 #include "internal-fn.h"
36 #include "gimple-iterator.h"
37 #include "gimplify-me.h"
39 #include "insn-config.h"
49 #include "tree-pass.h"
50 #include "langhooks.h"
53 #include "tree-data-ref.h"
54 #include "gimple-pretty-print.h"
55 #include "insn-codes.h"
57 #include "tree-scalar-evolution.h"
58 #include "tree-inline.h"
60 static unsigned int tree_ssa_phiopt_worker (bool, bool);
61 static bool conditional_replacement (basic_block
, basic_block
,
62 edge
, edge
, gphi
*, tree
, tree
);
63 static int value_replacement (basic_block
, basic_block
,
64 edge
, edge
, gimple
, tree
, tree
);
65 static bool minmax_replacement (basic_block
, basic_block
,
66 edge
, edge
, gimple
, tree
, tree
);
67 static bool abs_replacement (basic_block
, basic_block
,
68 edge
, edge
, gimple
, tree
, tree
);
69 static bool cond_store_replacement (basic_block
, basic_block
, edge
, edge
,
71 static bool cond_if_else_store_replacement (basic_block
, basic_block
, basic_block
);
72 static hash_set
<tree
> * get_non_trapping ();
73 static void replace_phi_edge_with_variable (basic_block
, edge
, gimple
, tree
);
74 static void hoist_adjacent_loads (basic_block
, basic_block
,
75 basic_block
, basic_block
);
76 static bool gate_hoist_loads (void);
78 /* This pass tries to transform conditional stores into unconditional
79 ones, enabling further simplifications with the simpler then and else
80 blocks. In particular it replaces this:
83 if (cond) goto bb2; else goto bb1;
91 if (cond) goto bb1; else goto bb2;
95 condtmp = PHI <RHS, condtmp'>
98 This transformation can only be done under several constraints,
99 documented below. It also replaces:
102 if (cond) goto bb2; else goto bb1;
113 if (cond) goto bb3; else goto bb1;
116 condtmp = PHI <RHS1, RHS2>
120 tree_ssa_cs_elim (void)
123 /* ??? We are not interested in loop related info, but the following
124 will create it, ICEing as we didn't init loops with pre-headers.
125 An interfacing issue of find_data_references_in_bb. */
126 loop_optimizer_init (LOOPS_NORMAL
);
128 todo
= tree_ssa_phiopt_worker (true, false);
130 loop_optimizer_finalize ();
134 /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
137 single_non_singleton_phi_for_edges (gimple_seq seq
, edge e0
, edge e1
)
139 gimple_stmt_iterator i
;
141 if (gimple_seq_singleton_p (seq
))
142 return as_a
<gphi
*> (gsi_stmt (gsi_start (seq
)));
143 for (i
= gsi_start (seq
); !gsi_end_p (i
); gsi_next (&i
))
145 gphi
*p
= as_a
<gphi
*> (gsi_stmt (i
));
146 /* If the PHI arguments are equal then we can skip this PHI. */
147 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p
, e0
->dest_idx
),
148 gimple_phi_arg_def (p
, e1
->dest_idx
)))
151 /* If we already have a PHI that has the two edge arguments are
152 different, then return it is not a singleton for these PHIs. */
161 /* The core routine of conditional store replacement and normal
162 phi optimizations. Both share much of the infrastructure in how
163 to match applicable basic block patterns. DO_STORE_ELIM is true
164 when we want to do conditional store replacement, false otherwise.
165 DO_HOIST_LOADS is true when we want to hoist adjacent loads out
166 of diamond control flow patterns, false otherwise. */
168 tree_ssa_phiopt_worker (bool do_store_elim
, bool do_hoist_loads
)
171 basic_block
*bb_order
;
173 bool cfgchanged
= false;
174 hash_set
<tree
> *nontrap
= 0;
177 /* Calculate the set of non-trapping memory accesses. */
178 nontrap
= get_non_trapping ();
180 /* Search every basic block for COND_EXPR we may be able to optimize.
182 We walk the blocks in order that guarantees that a block with
183 a single predecessor is processed before the predecessor.
184 This ensures that we collapse inner ifs before visiting the
185 outer ones, and also that we do not try to visit a removed
187 bb_order
= single_pred_before_succ_order ();
188 n
= n_basic_blocks_for_fn (cfun
) - NUM_FIXED_BLOCKS
;
190 for (i
= 0; i
< n
; i
++)
194 basic_block bb1
, bb2
;
200 cond_stmt
= last_stmt (bb
);
201 /* Check to see if the last statement is a GIMPLE_COND. */
203 || gimple_code (cond_stmt
) != GIMPLE_COND
)
206 e1
= EDGE_SUCC (bb
, 0);
208 e2
= EDGE_SUCC (bb
, 1);
211 /* We cannot do the optimization on abnormal edges. */
212 if ((e1
->flags
& EDGE_ABNORMAL
) != 0
213 || (e2
->flags
& EDGE_ABNORMAL
) != 0)
216 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
217 if (EDGE_COUNT (bb1
->succs
) == 0
219 || EDGE_COUNT (bb2
->succs
) == 0)
222 /* Find the bb which is the fall through to the other. */
223 if (EDGE_SUCC (bb1
, 0)->dest
== bb2
)
225 else if (EDGE_SUCC (bb2
, 0)->dest
== bb1
)
227 std::swap (bb1
, bb2
);
230 else if (do_store_elim
231 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
233 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
235 if (!single_succ_p (bb1
)
236 || (EDGE_SUCC (bb1
, 0)->flags
& EDGE_FALLTHRU
) == 0
237 || !single_succ_p (bb2
)
238 || (EDGE_SUCC (bb2
, 0)->flags
& EDGE_FALLTHRU
) == 0
239 || EDGE_COUNT (bb3
->preds
) != 2)
241 if (cond_if_else_store_replacement (bb1
, bb2
, bb3
))
245 else if (do_hoist_loads
246 && EDGE_SUCC (bb1
, 0)->dest
== EDGE_SUCC (bb2
, 0)->dest
)
248 basic_block bb3
= EDGE_SUCC (bb1
, 0)->dest
;
250 if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt
)))
251 && single_succ_p (bb1
)
252 && single_succ_p (bb2
)
253 && single_pred_p (bb1
)
254 && single_pred_p (bb2
)
255 && EDGE_COUNT (bb
->succs
) == 2
256 && EDGE_COUNT (bb3
->preds
) == 2
257 /* If one edge or the other is dominant, a conditional move
258 is likely to perform worse than the well-predicted branch. */
259 && !predictable_edge_p (EDGE_SUCC (bb
, 0))
260 && !predictable_edge_p (EDGE_SUCC (bb
, 1)))
261 hoist_adjacent_loads (bb
, bb1
, bb2
, bb3
);
267 e1
= EDGE_SUCC (bb1
, 0);
269 /* Make sure that bb1 is just a fall through. */
270 if (!single_succ_p (bb1
)
271 || (e1
->flags
& EDGE_FALLTHRU
) == 0)
274 /* Also make sure that bb1 only have one predecessor and that it
276 if (!single_pred_p (bb1
)
277 || single_pred (bb1
) != bb
)
282 /* bb1 is the middle block, bb2 the join block, bb the split block,
283 e1 the fallthrough edge from bb1 to bb2. We can't do the
284 optimization if the join block has more than two predecessors. */
285 if (EDGE_COUNT (bb2
->preds
) > 2)
287 if (cond_store_replacement (bb1
, bb2
, e1
, e2
, nontrap
))
292 gimple_seq phis
= phi_nodes (bb2
);
293 gimple_stmt_iterator gsi
;
294 bool candorest
= true;
296 /* Value replacement can work with more than one PHI
297 so try that first. */
298 for (gsi
= gsi_start (phis
); !gsi_end_p (gsi
); gsi_next (&gsi
))
300 phi
= as_a
<gphi
*> (gsi_stmt (gsi
));
301 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
302 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
303 if (value_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
) == 2)
314 phi
= single_non_singleton_phi_for_edges (phis
, e1
, e2
);
318 arg0
= gimple_phi_arg_def (phi
, e1
->dest_idx
);
319 arg1
= gimple_phi_arg_def (phi
, e2
->dest_idx
);
321 /* Something is wrong if we cannot find the arguments in the PHI
323 gcc_assert (arg0
!= NULL
&& arg1
!= NULL
);
325 /* Do the replacement of conditional if it can be done. */
326 if (conditional_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
328 else if (abs_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
330 else if (minmax_replacement (bb
, bb1
, e1
, e2
, phi
, arg0
, arg1
))
339 /* If the CFG has changed, we should cleanup the CFG. */
340 if (cfgchanged
&& do_store_elim
)
342 /* In cond-store replacement we have added some loads on edges
343 and new VOPS (as we moved the store, and created a load). */
344 gsi_commit_edge_inserts ();
345 return TODO_cleanup_cfg
| TODO_update_ssa_only_virtuals
;
348 return TODO_cleanup_cfg
;
352 /* Replace PHI node element whose edge is E in block BB with variable NEW.
353 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
354 is known to have two edges, one of which must reach BB). */
357 replace_phi_edge_with_variable (basic_block cond_block
,
358 edge e
, gimple phi
, tree new_tree
)
360 basic_block bb
= gimple_bb (phi
);
361 basic_block block_to_remove
;
362 gimple_stmt_iterator gsi
;
364 /* Change the PHI argument to new. */
365 SET_USE (PHI_ARG_DEF_PTR (phi
, e
->dest_idx
), new_tree
);
367 /* Remove the empty basic block. */
368 if (EDGE_SUCC (cond_block
, 0)->dest
== bb
)
370 EDGE_SUCC (cond_block
, 0)->flags
|= EDGE_FALLTHRU
;
371 EDGE_SUCC (cond_block
, 0)->flags
&= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
372 EDGE_SUCC (cond_block
, 0)->probability
= REG_BR_PROB_BASE
;
373 EDGE_SUCC (cond_block
, 0)->count
+= EDGE_SUCC (cond_block
, 1)->count
;
375 block_to_remove
= EDGE_SUCC (cond_block
, 1)->dest
;
379 EDGE_SUCC (cond_block
, 1)->flags
|= EDGE_FALLTHRU
;
380 EDGE_SUCC (cond_block
, 1)->flags
381 &= ~(EDGE_TRUE_VALUE
| EDGE_FALSE_VALUE
);
382 EDGE_SUCC (cond_block
, 1)->probability
= REG_BR_PROB_BASE
;
383 EDGE_SUCC (cond_block
, 1)->count
+= EDGE_SUCC (cond_block
, 0)->count
;
385 block_to_remove
= EDGE_SUCC (cond_block
, 0)->dest
;
387 delete_basic_block (block_to_remove
);
389 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
390 gsi
= gsi_last_bb (cond_block
);
391 gsi_remove (&gsi
, true);
393 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
395 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
400 /* The function conditional_replacement does the main work of doing the
401 conditional replacement. Return true if the replacement is done.
402 Otherwise return false.
403 BB is the basic block where the replacement is going to be done on. ARG0
404 is argument 0 from PHI. Likewise for ARG1. */
407 conditional_replacement (basic_block cond_bb
, basic_block middle_bb
,
408 edge e0
, edge e1
, gphi
*phi
,
409 tree arg0
, tree arg1
)
415 gimple_stmt_iterator gsi
;
416 edge true_edge
, false_edge
;
417 tree new_var
, new_var2
;
420 /* FIXME: Gimplification of complex type is too hard for now. */
421 /* We aren't prepared to handle vectors either (and it is a question
422 if it would be worthwhile anyway). */
423 if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
424 || POINTER_TYPE_P (TREE_TYPE (arg0
)))
425 || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1
))
426 || POINTER_TYPE_P (TREE_TYPE (arg1
))))
429 /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
430 convert it to the conditional. */
431 if ((integer_zerop (arg0
) && integer_onep (arg1
))
432 || (integer_zerop (arg1
) && integer_onep (arg0
)))
434 else if ((integer_zerop (arg0
) && integer_all_onesp (arg1
))
435 || (integer_zerop (arg1
) && integer_all_onesp (arg0
)))
440 if (!empty_block_p (middle_bb
))
443 /* At this point we know we have a GIMPLE_COND with two successors.
444 One successor is BB, the other successor is an empty block which
445 falls through into BB.
447 There is a single PHI node at the join point (BB) and its arguments
448 are constants (0, 1) or (0, -1).
450 So, given the condition COND, and the two PHI arguments, we can
451 rewrite this PHI into non-branching code:
453 dest = (COND) or dest = COND'
455 We use the condition as-is if the argument associated with the
456 true edge has the value one or the argument associated with the
457 false edge as the value zero. Note that those conditions are not
458 the same since only one of the outgoing edges from the GIMPLE_COND
459 will directly reach BB and thus be associated with an argument. */
461 stmt
= last_stmt (cond_bb
);
462 result
= PHI_RESULT (phi
);
464 /* To handle special cases like floating point comparison, it is easier and
465 less error-prone to build a tree and gimplify it on the fly though it is
467 cond
= fold_build2_loc (gimple_location (stmt
),
468 gimple_cond_code (stmt
), boolean_type_node
,
469 gimple_cond_lhs (stmt
), gimple_cond_rhs (stmt
));
471 /* We need to know which is the true edge and which is the false
472 edge so that we know when to invert the condition below. */
473 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
474 if ((e0
== true_edge
&& integer_zerop (arg0
))
475 || (e0
== false_edge
&& !integer_zerop (arg0
))
476 || (e1
== true_edge
&& integer_zerop (arg1
))
477 || (e1
== false_edge
&& !integer_zerop (arg1
)))
478 cond
= fold_build1_loc (gimple_location (stmt
),
479 TRUTH_NOT_EXPR
, TREE_TYPE (cond
), cond
);
483 cond
= fold_convert_loc (gimple_location (stmt
),
484 TREE_TYPE (result
), cond
);
485 cond
= fold_build1_loc (gimple_location (stmt
),
486 NEGATE_EXPR
, TREE_TYPE (cond
), cond
);
489 /* Insert our new statements at the end of conditional block before the
491 gsi
= gsi_for_stmt (stmt
);
492 new_var
= force_gimple_operand_gsi (&gsi
, cond
, true, NULL
, true,
495 if (!useless_type_conversion_p (TREE_TYPE (result
), TREE_TYPE (new_var
)))
497 source_location locus_0
, locus_1
;
499 new_var2
= make_ssa_name (TREE_TYPE (result
));
500 new_stmt
= gimple_build_assign (new_var2
, CONVERT_EXPR
, new_var
);
501 gsi_insert_before (&gsi
, new_stmt
, GSI_SAME_STMT
);
504 /* Set the locus to the first argument, unless is doesn't have one. */
505 locus_0
= gimple_phi_arg_location (phi
, 0);
506 locus_1
= gimple_phi_arg_location (phi
, 1);
507 if (locus_0
== UNKNOWN_LOCATION
)
509 gimple_set_location (new_stmt
, locus_0
);
512 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, new_var
);
514 /* Note that we optimized this PHI. */
518 /* Update *ARG which is defined in STMT so that it contains the
519 computed value if that seems profitable. Return true if the
520 statement is made dead by that rewriting. */
523 jump_function_from_stmt (tree
*arg
, gimple stmt
)
525 enum tree_code code
= gimple_assign_rhs_code (stmt
);
526 if (code
== ADDR_EXPR
)
528 /* For arg = &p->i transform it to p, if possible. */
529 tree rhs1
= gimple_assign_rhs1 (stmt
);
530 HOST_WIDE_INT offset
;
531 tree tem
= get_addr_base_and_unit_offset (TREE_OPERAND (rhs1
, 0),
534 && TREE_CODE (tem
) == MEM_REF
535 && (mem_ref_offset (tem
) + offset
) == 0)
537 *arg
= TREE_OPERAND (tem
, 0);
541 /* TODO: Much like IPA-CP jump-functions we want to handle constant
542 additions symbolically here, and we'd need to update the comparison
543 code that compares the arg + cst tuples in our caller. For now the
544 code above exactly handles the VEC_BASE pattern from vec.h. */
548 /* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
549 of the form SSA_NAME NE 0.
551 If RHS is fed by a simple EQ_EXPR comparison of two values, see if
552 the two input values of the EQ_EXPR match arg0 and arg1.
554 If so update *code and return TRUE. Otherwise return FALSE. */
557 rhs_is_fed_for_value_replacement (const_tree arg0
, const_tree arg1
,
558 enum tree_code
*code
, const_tree rhs
)
560 /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
562 if (TREE_CODE (rhs
) == SSA_NAME
)
564 gimple def1
= SSA_NAME_DEF_STMT (rhs
);
566 /* Verify the defining statement has an EQ_EXPR on the RHS. */
567 if (is_gimple_assign (def1
) && gimple_assign_rhs_code (def1
) == EQ_EXPR
)
569 /* Finally verify the source operands of the EQ_EXPR are equal
571 tree op0
= gimple_assign_rhs1 (def1
);
572 tree op1
= gimple_assign_rhs2 (def1
);
573 if ((operand_equal_for_phi_arg_p (arg0
, op0
)
574 && operand_equal_for_phi_arg_p (arg1
, op1
))
575 || (operand_equal_for_phi_arg_p (arg0
, op1
)
576 && operand_equal_for_phi_arg_p (arg1
, op0
)))
578 /* We will perform the optimization. */
579 *code
= gimple_assign_rhs_code (def1
);
587 /* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
589 Also return TRUE if arg0/arg1 are equal to the source arguments of a
590 an EQ comparison feeding a BIT_AND_EXPR which feeds COND.
592 Return FALSE otherwise. */
595 operand_equal_for_value_replacement (const_tree arg0
, const_tree arg1
,
596 enum tree_code
*code
, gimple cond
)
599 tree lhs
= gimple_cond_lhs (cond
);
600 tree rhs
= gimple_cond_rhs (cond
);
602 if ((operand_equal_for_phi_arg_p (arg0
, lhs
)
603 && operand_equal_for_phi_arg_p (arg1
, rhs
))
604 || (operand_equal_for_phi_arg_p (arg1
, lhs
)
605 && operand_equal_for_phi_arg_p (arg0
, rhs
)))
608 /* Now handle more complex case where we have an EQ comparison
609 which feeds a BIT_AND_EXPR which feeds COND.
611 First verify that COND is of the form SSA_NAME NE 0. */
612 if (*code
!= NE_EXPR
|| !integer_zerop (rhs
)
613 || TREE_CODE (lhs
) != SSA_NAME
)
616 /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */
617 def
= SSA_NAME_DEF_STMT (lhs
);
618 if (!is_gimple_assign (def
) || gimple_assign_rhs_code (def
) != BIT_AND_EXPR
)
621 /* Now verify arg0/arg1 correspond to the source arguments of an
622 EQ comparison feeding the BIT_AND_EXPR. */
624 tree tmp
= gimple_assign_rhs1 (def
);
625 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
628 tmp
= gimple_assign_rhs2 (def
);
629 if (rhs_is_fed_for_value_replacement (arg0
, arg1
, code
, tmp
))
635 /* Returns true if ARG is a neutral element for operation CODE
636 on the RIGHT side. */
639 neutral_element_p (tree_code code
, tree arg
, bool right
)
646 return integer_zerop (arg
);
653 case POINTER_PLUS_EXPR
:
654 return right
&& integer_zerop (arg
);
657 return integer_onep (arg
);
664 return right
&& integer_onep (arg
);
667 return integer_all_onesp (arg
);
674 /* Returns true if ARG is an absorbing element for operation CODE. */
677 absorbing_element_p (tree_code code
, tree arg
)
682 return integer_all_onesp (arg
);
686 return integer_zerop (arg
);
693 /* The function value_replacement does the main work of doing the value
694 replacement. Return non-zero if the replacement is done. Otherwise return
695 0. If we remove the middle basic block, return 2.
696 BB is the basic block where the replacement is going to be done on. ARG0
697 is argument 0 from the PHI. Likewise for ARG1. */
700 value_replacement (basic_block cond_bb
, basic_block middle_bb
,
701 edge e0
, edge e1
, gimple phi
,
702 tree arg0
, tree arg1
)
704 gimple_stmt_iterator gsi
;
706 edge true_edge
, false_edge
;
708 bool emtpy_or_with_defined_p
= true;
710 /* If the type says honor signed zeros we cannot do this
712 if (HONOR_SIGNED_ZEROS (arg1
))
715 /* If there is a statement in MIDDLE_BB that defines one of the PHI
716 arguments, then adjust arg0 or arg1. */
717 gsi
= gsi_start_nondebug_after_labels_bb (middle_bb
);
718 while (!gsi_end_p (gsi
))
720 gimple stmt
= gsi_stmt (gsi
);
722 gsi_next_nondebug (&gsi
);
723 if (!is_gimple_assign (stmt
))
725 emtpy_or_with_defined_p
= false;
728 /* Now try to adjust arg0 or arg1 according to the computation
730 lhs
= gimple_assign_lhs (stmt
);
732 && jump_function_from_stmt (&arg0
, stmt
))
734 && jump_function_from_stmt (&arg1
, stmt
)))
735 emtpy_or_with_defined_p
= false;
738 cond
= last_stmt (cond_bb
);
739 code
= gimple_cond_code (cond
);
741 /* This transformation is only valid for equality comparisons. */
742 if (code
!= NE_EXPR
&& code
!= EQ_EXPR
)
745 /* We need to know which is the true edge and which is the false
746 edge so that we know if have abs or negative abs. */
747 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
749 /* At this point we know we have a COND_EXPR with two successors.
750 One successor is BB, the other successor is an empty block which
751 falls through into BB.
753 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
755 There is a single PHI node at the join point (BB) with two arguments.
757 We now need to verify that the two arguments in the PHI node match
758 the two arguments to the equality comparison. */
760 if (operand_equal_for_value_replacement (arg0
, arg1
, &code
, cond
))
765 /* For NE_EXPR, we want to build an assignment result = arg where
766 arg is the PHI argument associated with the true edge. For
767 EQ_EXPR we want the PHI argument associated with the false edge. */
768 e
= (code
== NE_EXPR
? true_edge
: false_edge
);
770 /* Unfortunately, E may not reach BB (it may instead have gone to
771 OTHER_BLOCK). If that is the case, then we want the single outgoing
772 edge from OTHER_BLOCK which reaches BB and represents the desired
773 path from COND_BLOCK. */
774 if (e
->dest
== middle_bb
)
775 e
= single_succ_edge (e
->dest
);
777 /* Now we know the incoming edge to BB that has the argument for the
778 RHS of our new assignment statement. */
784 /* If the middle basic block was empty or is defining the
785 PHI arguments and this is a single phi where the args are different
786 for the edges e0 and e1 then we can remove the middle basic block. */
787 if (emtpy_or_with_defined_p
788 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)),
791 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, arg
);
792 /* Note that we optimized this PHI. */
797 /* Replace the PHI arguments with arg. */
798 SET_PHI_ARG_DEF (phi
, e0
->dest_idx
, arg
);
799 SET_PHI_ARG_DEF (phi
, e1
->dest_idx
, arg
);
800 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
802 fprintf (dump_file
, "PHI ");
803 print_generic_expr (dump_file
, gimple_phi_result (phi
), 0);
804 fprintf (dump_file
, " reduced for COND_EXPR in block %d to ",
806 print_generic_expr (dump_file
, arg
, 0);
807 fprintf (dump_file
, ".\n");
814 /* Now optimize (x != 0) ? x + y : y to just y.
815 The following condition is too restrictive, there can easily be another
816 stmt in middle_bb, for instance a CONVERT_EXPR for the second argument. */
817 gimple assign
= last_and_only_stmt (middle_bb
);
818 if (!assign
|| gimple_code (assign
) != GIMPLE_ASSIGN
819 || gimple_assign_rhs_class (assign
) != GIMPLE_BINARY_RHS
820 || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0
))
821 && !POINTER_TYPE_P (TREE_TYPE (arg0
))))
824 /* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */
825 if (!gimple_seq_empty_p (phi_nodes (middle_bb
)))
828 /* Only transform if it removes the condition. */
829 if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi
)), e0
, e1
))
832 /* Size-wise, this is always profitable. */
833 if (optimize_bb_for_speed_p (cond_bb
)
834 /* The special case is useless if it has a low probability. */
835 && profile_status_for_fn (cfun
) != PROFILE_ABSENT
836 && EDGE_PRED (middle_bb
, 0)->probability
< PROB_EVEN
837 /* If assign is cheap, there is no point avoiding it. */
838 && estimate_num_insns (assign
, &eni_time_weights
)
839 >= 3 * estimate_num_insns (cond
, &eni_time_weights
))
842 tree lhs
= gimple_assign_lhs (assign
);
843 tree rhs1
= gimple_assign_rhs1 (assign
);
844 tree rhs2
= gimple_assign_rhs2 (assign
);
845 enum tree_code code_def
= gimple_assign_rhs_code (assign
);
846 tree cond_lhs
= gimple_cond_lhs (cond
);
847 tree cond_rhs
= gimple_cond_rhs (cond
);
849 if (((code
== NE_EXPR
&& e1
== false_edge
)
850 || (code
== EQ_EXPR
&& e1
== true_edge
))
853 && operand_equal_for_phi_arg_p (rhs2
, cond_lhs
)
854 && neutral_element_p (code_def
, cond_rhs
, true))
856 && operand_equal_for_phi_arg_p (rhs1
, cond_lhs
)
857 && neutral_element_p (code_def
, cond_rhs
, false))
858 || (operand_equal_for_phi_arg_p (arg1
, cond_rhs
)
859 && (operand_equal_for_phi_arg_p (rhs2
, cond_lhs
)
860 || operand_equal_for_phi_arg_p (rhs1
, cond_lhs
))
861 && absorbing_element_p (code_def
, cond_rhs
))))
863 gsi
= gsi_for_stmt (cond
);
864 if (INTEGRAL_TYPE_P (TREE_TYPE (lhs
)))
866 /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6
874 # RANGE [0, 4294967294]
875 u_6 = n_5 + 4294967295;
878 # u_3 = PHI <u_6(3), 4294967295(2)> */
879 SSA_NAME_RANGE_INFO (lhs
) = NULL
;
880 SSA_NAME_ANTI_RANGE_P (lhs
) = 0;
881 /* If available, we can use VR of phi result at least. */
882 tree phires
= gimple_phi_result (phi
);
883 struct range_info_def
*phires_range_info
884 = SSA_NAME_RANGE_INFO (phires
);
885 if (phires_range_info
)
886 duplicate_ssa_name_range_info (lhs
, SSA_NAME_RANGE_TYPE (phires
),
889 gimple_stmt_iterator gsi_from
= gsi_for_stmt (assign
);
890 gsi_move_before (&gsi_from
, &gsi
);
891 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, lhs
);
898 /* The function minmax_replacement does the main work of doing the minmax
899 replacement. Return true if the replacement is done. Otherwise return
901 BB is the basic block where the replacement is going to be done on. ARG0
902 is argument 0 from the PHI. Likewise for ARG1. */
905 minmax_replacement (basic_block cond_bb
, basic_block middle_bb
,
906 edge e0
, edge e1
, gimple phi
,
907 tree arg0
, tree arg1
)
912 edge true_edge
, false_edge
;
913 enum tree_code cmp
, minmax
, ass_code
;
914 tree smaller
, larger
, arg_true
, arg_false
;
915 gimple_stmt_iterator gsi
, gsi_from
;
917 type
= TREE_TYPE (PHI_RESULT (phi
));
919 /* The optimization may be unsafe due to NaNs. */
920 if (HONOR_NANS (type
))
923 cond
= as_a
<gcond
*> (last_stmt (cond_bb
));
924 cmp
= gimple_cond_code (cond
);
926 /* This transformation is only valid for order comparisons. Record which
927 operand is smaller/larger if the result of the comparison is true. */
928 if (cmp
== LT_EXPR
|| cmp
== LE_EXPR
)
930 smaller
= gimple_cond_lhs (cond
);
931 larger
= gimple_cond_rhs (cond
);
933 else if (cmp
== GT_EXPR
|| cmp
== GE_EXPR
)
935 smaller
= gimple_cond_rhs (cond
);
936 larger
= gimple_cond_lhs (cond
);
941 /* We need to know which is the true edge and which is the false
942 edge so that we know if have abs or negative abs. */
943 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
945 /* Forward the edges over the middle basic block. */
946 if (true_edge
->dest
== middle_bb
)
947 true_edge
= EDGE_SUCC (true_edge
->dest
, 0);
948 if (false_edge
->dest
== middle_bb
)
949 false_edge
= EDGE_SUCC (false_edge
->dest
, 0);
953 gcc_assert (false_edge
== e1
);
959 gcc_assert (false_edge
== e0
);
960 gcc_assert (true_edge
== e1
);
965 if (empty_block_p (middle_bb
))
967 if (operand_equal_for_phi_arg_p (arg_true
, smaller
)
968 && operand_equal_for_phi_arg_p (arg_false
, larger
))
972 if (smaller < larger)
978 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
)
979 && operand_equal_for_phi_arg_p (arg_true
, larger
))
986 /* Recognize the following case, assuming d <= u:
992 This is equivalent to
997 gimple assign
= last_and_only_stmt (middle_bb
);
998 tree lhs
, op0
, op1
, bound
;
1001 || gimple_code (assign
) != GIMPLE_ASSIGN
)
1004 lhs
= gimple_assign_lhs (assign
);
1005 ass_code
= gimple_assign_rhs_code (assign
);
1006 if (ass_code
!= MAX_EXPR
&& ass_code
!= MIN_EXPR
)
1008 op0
= gimple_assign_rhs1 (assign
);
1009 op1
= gimple_assign_rhs2 (assign
);
1011 if (true_edge
->src
== middle_bb
)
1013 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
1014 if (!operand_equal_for_phi_arg_p (lhs
, arg_true
))
1017 if (operand_equal_for_phi_arg_p (arg_false
, larger
))
1021 if (smaller < larger)
1023 r' = MAX_EXPR (smaller, bound)
1025 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
1026 if (ass_code
!= MAX_EXPR
)
1030 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1032 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1037 /* We need BOUND <= LARGER. */
1038 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1042 else if (operand_equal_for_phi_arg_p (arg_false
, smaller
))
1046 if (smaller < larger)
1048 r' = MIN_EXPR (larger, bound)
1050 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
1051 if (ass_code
!= MIN_EXPR
)
1055 if (operand_equal_for_phi_arg_p (op0
, larger
))
1057 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1062 /* We need BOUND >= SMALLER. */
1063 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1072 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
1073 if (!operand_equal_for_phi_arg_p (lhs
, arg_false
))
1076 if (operand_equal_for_phi_arg_p (arg_true
, larger
))
1080 if (smaller > larger)
1082 r' = MIN_EXPR (smaller, bound)
1084 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
1085 if (ass_code
!= MIN_EXPR
)
1089 if (operand_equal_for_phi_arg_p (op0
, smaller
))
1091 else if (operand_equal_for_phi_arg_p (op1
, smaller
))
1096 /* We need BOUND >= LARGER. */
1097 if (!integer_nonzerop (fold_build2 (GE_EXPR
, boolean_type_node
,
1101 else if (operand_equal_for_phi_arg_p (arg_true
, smaller
))
1105 if (smaller > larger)
1107 r' = MAX_EXPR (larger, bound)
1109 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
1110 if (ass_code
!= MAX_EXPR
)
1114 if (operand_equal_for_phi_arg_p (op0
, larger
))
1116 else if (operand_equal_for_phi_arg_p (op1
, larger
))
1121 /* We need BOUND <= SMALLER. */
1122 if (!integer_nonzerop (fold_build2 (LE_EXPR
, boolean_type_node
,
1130 /* Move the statement from the middle block. */
1131 gsi
= gsi_last_bb (cond_bb
);
1132 gsi_from
= gsi_last_nondebug_bb (middle_bb
);
1133 gsi_move_before (&gsi_from
, &gsi
);
1136 /* Emit the statement to compute min/max. */
1137 result
= duplicate_ssa_name (PHI_RESULT (phi
), NULL
);
1138 new_stmt
= gimple_build_assign (result
, minmax
, arg0
, arg1
);
1139 gsi
= gsi_last_bb (cond_bb
);
1140 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1142 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1146 /* The function absolute_replacement does the main work of doing the absolute
1147 replacement. Return true if the replacement is done. Otherwise return
1149 bb is the basic block where the replacement is going to be done on. arg0
1150 is argument 0 from the phi. Likewise for arg1. */
1153 abs_replacement (basic_block cond_bb
, basic_block middle_bb
,
1154 edge e0 ATTRIBUTE_UNUSED
, edge e1
,
1155 gimple phi
, tree arg0
, tree arg1
)
1160 gimple_stmt_iterator gsi
;
1161 edge true_edge
, false_edge
;
1166 enum tree_code cond_code
;
1168 /* If the type says honor signed zeros we cannot do this
1170 if (HONOR_SIGNED_ZEROS (arg1
))
1173 /* OTHER_BLOCK must have only one executable statement which must have the
1174 form arg0 = -arg1 or arg1 = -arg0. */
1176 assign
= last_and_only_stmt (middle_bb
);
1177 /* If we did not find the proper negation assignment, then we can not
1182 /* If we got here, then we have found the only executable statement
1183 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1184 arg1 = -arg0, then we can not optimize. */
1185 if (gimple_code (assign
) != GIMPLE_ASSIGN
)
1188 lhs
= gimple_assign_lhs (assign
);
1190 if (gimple_assign_rhs_code (assign
) != NEGATE_EXPR
)
1193 rhs
= gimple_assign_rhs1 (assign
);
1195 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1196 if (!(lhs
== arg0
&& rhs
== arg1
)
1197 && !(lhs
== arg1
&& rhs
== arg0
))
1200 cond
= last_stmt (cond_bb
);
1201 result
= PHI_RESULT (phi
);
1203 /* Only relationals comparing arg[01] against zero are interesting. */
1204 cond_code
= gimple_cond_code (cond
);
1205 if (cond_code
!= GT_EXPR
&& cond_code
!= GE_EXPR
1206 && cond_code
!= LT_EXPR
&& cond_code
!= LE_EXPR
)
1209 /* Make sure the conditional is arg[01] OP y. */
1210 if (gimple_cond_lhs (cond
) != rhs
)
1213 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond
)))
1214 ? real_zerop (gimple_cond_rhs (cond
))
1215 : integer_zerop (gimple_cond_rhs (cond
)))
1220 /* We need to know which is the true edge and which is the false
1221 edge so that we know if have abs or negative abs. */
1222 extract_true_false_edges_from_block (cond_bb
, &true_edge
, &false_edge
);
1224 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1225 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1226 the false edge goes to OTHER_BLOCK. */
1227 if (cond_code
== GT_EXPR
|| cond_code
== GE_EXPR
)
1232 if (e
->dest
== middle_bb
)
1237 result
= duplicate_ssa_name (result
, NULL
);
1240 lhs
= make_ssa_name (TREE_TYPE (result
));
1244 /* Build the modify expression with abs expression. */
1245 new_stmt
= gimple_build_assign (lhs
, ABS_EXPR
, rhs
);
1247 gsi
= gsi_last_bb (cond_bb
);
1248 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1252 /* Get the right GSI. We want to insert after the recently
1253 added ABS_EXPR statement (which we know is the first statement
1255 new_stmt
= gimple_build_assign (result
, NEGATE_EXPR
, lhs
);
1257 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1260 replace_phi_edge_with_variable (cond_bb
, e1
, phi
, result
);
1262 /* Note that we optimized this PHI. */
1266 /* Auxiliary functions to determine the set of memory accesses which
1267 can't trap because they are preceded by accesses to the same memory
1268 portion. We do that for MEM_REFs, so we only need to track
1269 the SSA_NAME of the pointer indirectly referenced. The algorithm
1270 simply is a walk over all instructions in dominator order. When
1271 we see an MEM_REF we determine if we've already seen a same
1272 ref anywhere up to the root of the dominator tree. If we do the
1273 current access can't trap. If we don't see any dominating access
1274 the current access might trap, but might also make later accesses
1275 non-trapping, so we remember it. We need to be careful with loads
1276 or stores, for instance a load might not trap, while a store would,
1277 so if we see a dominating read access this doesn't mean that a later
1278 write access would not trap. Hence we also need to differentiate the
1279 type of access(es) seen.
1281 ??? We currently are very conservative and assume that a load might
1282 trap even if a store doesn't (write-only memory). This probably is
1283 overly conservative. */
1285 /* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1286 through it was seen, which would constitute a no-trap region for
1290 unsigned int ssa_name_ver
;
1293 HOST_WIDE_INT offset
, size
;
1297 /* Hashtable helpers. */
1299 struct ssa_names_hasher
: free_ptr_hash
<name_to_bb
>
1301 static inline hashval_t
hash (const name_to_bb
*);
1302 static inline bool equal (const name_to_bb
*, const name_to_bb
*);
1305 /* Used for quick clearing of the hash-table when we see calls.
1306 Hash entries with phase < nt_call_phase are invalid. */
1307 static unsigned int nt_call_phase
;
1309 /* The hash function. */
1312 ssa_names_hasher::hash (const name_to_bb
*n
)
1314 return n
->ssa_name_ver
^ (((hashval_t
) n
->store
) << 31)
1315 ^ (n
->offset
<< 6) ^ (n
->size
<< 3);
1318 /* The equality function of *P1 and *P2. */
1321 ssa_names_hasher::equal (const name_to_bb
*n1
, const name_to_bb
*n2
)
1323 return n1
->ssa_name_ver
== n2
->ssa_name_ver
1324 && n1
->store
== n2
->store
1325 && n1
->offset
== n2
->offset
1326 && n1
->size
== n2
->size
;
1329 class nontrapping_dom_walker
: public dom_walker
1332 nontrapping_dom_walker (cdi_direction direction
, hash_set
<tree
> *ps
)
1333 : dom_walker (direction
), m_nontrapping (ps
), m_seen_ssa_names (128) {}
1335 virtual void before_dom_children (basic_block
);
1336 virtual void after_dom_children (basic_block
);
1340 /* We see the expression EXP in basic block BB. If it's an interesting
1341 expression (an MEM_REF through an SSA_NAME) possibly insert the
1342 expression into the set NONTRAP or the hash table of seen expressions.
1343 STORE is true if this expression is on the LHS, otherwise it's on
1345 void add_or_mark_expr (basic_block
, tree
, bool);
1347 hash_set
<tree
> *m_nontrapping
;
1349 /* The hash table for remembering what we've seen. */
1350 hash_table
<ssa_names_hasher
> m_seen_ssa_names
;
1353 /* Called by walk_dominator_tree, when entering the block BB. */
1355 nontrapping_dom_walker::before_dom_children (basic_block bb
)
1359 gimple_stmt_iterator gsi
;
1361 /* If we haven't seen all our predecessors, clear the hash-table. */
1362 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1363 if ((((size_t)e
->src
->aux
) & 2) == 0)
1369 /* Mark this BB as being on the path to dominator root and as visited. */
1370 bb
->aux
= (void*)(1 | 2);
1372 /* And walk the statements in order. */
1373 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1375 gimple stmt
= gsi_stmt (gsi
);
1377 if (is_gimple_call (stmt
) && !nonfreeing_call_p (stmt
))
1379 else if (gimple_assign_single_p (stmt
) && !gimple_has_volatile_ops (stmt
))
1381 add_or_mark_expr (bb
, gimple_assign_lhs (stmt
), true);
1382 add_or_mark_expr (bb
, gimple_assign_rhs1 (stmt
), false);
1387 /* Called by walk_dominator_tree, when basic block BB is exited. */
1389 nontrapping_dom_walker::after_dom_children (basic_block bb
)
1391 /* This BB isn't on the path to dominator root anymore. */
1395 /* We see the expression EXP in basic block BB. If it's an interesting
1396 expression (an MEM_REF through an SSA_NAME) possibly insert the
1397 expression into the set NONTRAP or the hash table of seen expressions.
1398 STORE is true if this expression is on the LHS, otherwise it's on
1401 nontrapping_dom_walker::add_or_mark_expr (basic_block bb
, tree exp
, bool store
)
1405 if (TREE_CODE (exp
) == MEM_REF
1406 && TREE_CODE (TREE_OPERAND (exp
, 0)) == SSA_NAME
1407 && tree_fits_shwi_p (TREE_OPERAND (exp
, 1))
1408 && (size
= int_size_in_bytes (TREE_TYPE (exp
))) > 0)
1410 tree name
= TREE_OPERAND (exp
, 0);
1411 struct name_to_bb map
;
1413 struct name_to_bb
*n2bb
;
1414 basic_block found_bb
= 0;
1416 /* Try to find the last seen MEM_REF through the same
1417 SSA_NAME, which can trap. */
1418 map
.ssa_name_ver
= SSA_NAME_VERSION (name
);
1422 map
.offset
= tree_to_shwi (TREE_OPERAND (exp
, 1));
1425 slot
= m_seen_ssa_names
.find_slot (&map
, INSERT
);
1427 if (n2bb
&& n2bb
->phase
>= nt_call_phase
)
1428 found_bb
= n2bb
->bb
;
1430 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1431 (it's in a basic block on the path from us to the dominator root)
1432 then we can't trap. */
1433 if (found_bb
&& (((size_t)found_bb
->aux
) & 1) == 1)
1435 m_nontrapping
->add (exp
);
1439 /* EXP might trap, so insert it into the hash table. */
1442 n2bb
->phase
= nt_call_phase
;
1447 n2bb
= XNEW (struct name_to_bb
);
1448 n2bb
->ssa_name_ver
= SSA_NAME_VERSION (name
);
1449 n2bb
->phase
= nt_call_phase
;
1451 n2bb
->store
= store
;
1452 n2bb
->offset
= map
.offset
;
1460 /* This is the entry point of gathering non trapping memory accesses.
1461 It will do a dominator walk over the whole function, and it will
1462 make use of the bb->aux pointers. It returns a set of trees
1463 (the MEM_REFs itself) which can't trap. */
1464 static hash_set
<tree
> *
1465 get_non_trapping (void)
1468 hash_set
<tree
> *nontrap
= new hash_set
<tree
>;
1469 /* We're going to do a dominator walk, so ensure that we have
1470 dominance information. */
1471 calculate_dominance_info (CDI_DOMINATORS
);
1473 nontrapping_dom_walker (CDI_DOMINATORS
, nontrap
)
1474 .walk (cfun
->cfg
->x_entry_block_ptr
);
1476 clear_aux_for_blocks ();
1480 /* Do the main work of conditional store replacement. We already know
1481 that the recognized pattern looks like so:
1484 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1487 fallthrough (edge E0)
1491 We check that MIDDLE_BB contains only one store, that that store
1492 doesn't trap (not via NOTRAP, but via checking if an access to the same
1493 memory location dominates us) and that the store has a "simple" RHS. */
1496 cond_store_replacement (basic_block middle_bb
, basic_block join_bb
,
1497 edge e0
, edge e1
, hash_set
<tree
> *nontrap
)
1499 gimple assign
= last_and_only_stmt (middle_bb
);
1500 tree lhs
, rhs
, name
, name2
;
1503 gimple_stmt_iterator gsi
;
1504 source_location locus
;
1506 /* Check if middle_bb contains of only one store. */
1508 || !gimple_assign_single_p (assign
)
1509 || gimple_has_volatile_ops (assign
))
1512 locus
= gimple_location (assign
);
1513 lhs
= gimple_assign_lhs (assign
);
1514 rhs
= gimple_assign_rhs1 (assign
);
1515 if (TREE_CODE (lhs
) != MEM_REF
1516 || TREE_CODE (TREE_OPERAND (lhs
, 0)) != SSA_NAME
1517 || !is_gimple_reg_type (TREE_TYPE (lhs
)))
1520 /* Prove that we can move the store down. We could also check
1521 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1522 whose value is not available readily, which we want to avoid. */
1523 if (!nontrap
->contains (lhs
))
1526 /* Now we've checked the constraints, so do the transformation:
1527 1) Remove the single store. */
1528 gsi
= gsi_for_stmt (assign
);
1529 unlink_stmt_vdef (assign
);
1530 gsi_remove (&gsi
, true);
1531 release_defs (assign
);
1533 /* 2) Insert a load from the memory of the store to the temporary
1534 on the edge which did not contain the store. */
1535 lhs
= unshare_expr (lhs
);
1536 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1537 new_stmt
= gimple_build_assign (name
, lhs
);
1538 gimple_set_location (new_stmt
, locus
);
1539 gsi_insert_on_edge (e1
, new_stmt
);
1541 /* 3) Create a PHI node at the join block, with one argument
1542 holding the old RHS, and the other holding the temporary
1543 where we stored the old memory contents. */
1544 name2
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1545 newphi
= create_phi_node (name2
, join_bb
);
1546 add_phi_arg (newphi
, rhs
, e0
, locus
);
1547 add_phi_arg (newphi
, name
, e1
, locus
);
1549 lhs
= unshare_expr (lhs
);
1550 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1552 /* 4) Insert that PHI node. */
1553 gsi
= gsi_after_labels (join_bb
);
1554 if (gsi_end_p (gsi
))
1556 gsi
= gsi_last_bb (join_bb
);
1557 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1560 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1565 /* Do the main work of conditional store replacement. */
1568 cond_if_else_store_replacement_1 (basic_block then_bb
, basic_block else_bb
,
1569 basic_block join_bb
, gimple then_assign
,
1572 tree lhs_base
, lhs
, then_rhs
, else_rhs
, name
;
1573 source_location then_locus
, else_locus
;
1574 gimple_stmt_iterator gsi
;
1578 if (then_assign
== NULL
1579 || !gimple_assign_single_p (then_assign
)
1580 || gimple_clobber_p (then_assign
)
1581 || gimple_has_volatile_ops (then_assign
)
1582 || else_assign
== NULL
1583 || !gimple_assign_single_p (else_assign
)
1584 || gimple_clobber_p (else_assign
)
1585 || gimple_has_volatile_ops (else_assign
))
1588 lhs
= gimple_assign_lhs (then_assign
);
1589 if (!is_gimple_reg_type (TREE_TYPE (lhs
))
1590 || !operand_equal_p (lhs
, gimple_assign_lhs (else_assign
), 0))
1593 lhs_base
= get_base_address (lhs
);
1594 if (lhs_base
== NULL_TREE
1595 || (!DECL_P (lhs_base
) && TREE_CODE (lhs_base
) != MEM_REF
))
1598 then_rhs
= gimple_assign_rhs1 (then_assign
);
1599 else_rhs
= gimple_assign_rhs1 (else_assign
);
1600 then_locus
= gimple_location (then_assign
);
1601 else_locus
= gimple_location (else_assign
);
1603 /* Now we've checked the constraints, so do the transformation:
1604 1) Remove the stores. */
1605 gsi
= gsi_for_stmt (then_assign
);
1606 unlink_stmt_vdef (then_assign
);
1607 gsi_remove (&gsi
, true);
1608 release_defs (then_assign
);
1610 gsi
= gsi_for_stmt (else_assign
);
1611 unlink_stmt_vdef (else_assign
);
1612 gsi_remove (&gsi
, true);
1613 release_defs (else_assign
);
1615 /* 2) Create a PHI node at the join block, with one argument
1616 holding the old RHS, and the other holding the temporary
1617 where we stored the old memory contents. */
1618 name
= make_temp_ssa_name (TREE_TYPE (lhs
), NULL
, "cstore");
1619 newphi
= create_phi_node (name
, join_bb
);
1620 add_phi_arg (newphi
, then_rhs
, EDGE_SUCC (then_bb
, 0), then_locus
);
1621 add_phi_arg (newphi
, else_rhs
, EDGE_SUCC (else_bb
, 0), else_locus
);
1623 new_stmt
= gimple_build_assign (lhs
, PHI_RESULT (newphi
));
1625 /* 3) Insert that PHI node. */
1626 gsi
= gsi_after_labels (join_bb
);
1627 if (gsi_end_p (gsi
))
1629 gsi
= gsi_last_bb (join_bb
);
1630 gsi_insert_after (&gsi
, new_stmt
, GSI_NEW_STMT
);
1633 gsi_insert_before (&gsi
, new_stmt
, GSI_NEW_STMT
);
1638 /* Conditional store replacement. We already know
1639 that the recognized pattern looks like so:
1642 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
1652 fallthrough (edge E0)
1656 We check that it is safe to sink the store to JOIN_BB by verifying that
1657 there are no read-after-write or write-after-write dependencies in
1658 THEN_BB and ELSE_BB. */
1661 cond_if_else_store_replacement (basic_block then_bb
, basic_block else_bb
,
1662 basic_block join_bb
)
1664 gimple then_assign
= last_and_only_stmt (then_bb
);
1665 gimple else_assign
= last_and_only_stmt (else_bb
);
1666 vec
<data_reference_p
> then_datarefs
, else_datarefs
;
1667 vec
<ddr_p
> then_ddrs
, else_ddrs
;
1668 gimple then_store
, else_store
;
1669 bool found
, ok
= false, res
;
1670 struct data_dependence_relation
*ddr
;
1671 data_reference_p then_dr
, else_dr
;
1673 tree then_lhs
, else_lhs
;
1674 basic_block blocks
[3];
1676 if (MAX_STORES_TO_SINK
== 0)
1679 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
1680 if (then_assign
&& else_assign
)
1681 return cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1682 then_assign
, else_assign
);
1684 /* Find data references. */
1685 then_datarefs
.create (1);
1686 else_datarefs
.create (1);
1687 if ((find_data_references_in_bb (NULL
, then_bb
, &then_datarefs
)
1689 || !then_datarefs
.length ()
1690 || (find_data_references_in_bb (NULL
, else_bb
, &else_datarefs
)
1692 || !else_datarefs
.length ())
1694 free_data_refs (then_datarefs
);
1695 free_data_refs (else_datarefs
);
1699 /* Find pairs of stores with equal LHS. */
1700 auto_vec
<gimple
, 1> then_stores
, else_stores
;
1701 FOR_EACH_VEC_ELT (then_datarefs
, i
, then_dr
)
1703 if (DR_IS_READ (then_dr
))
1706 then_store
= DR_STMT (then_dr
);
1707 then_lhs
= gimple_get_lhs (then_store
);
1708 if (then_lhs
== NULL_TREE
)
1712 FOR_EACH_VEC_ELT (else_datarefs
, j
, else_dr
)
1714 if (DR_IS_READ (else_dr
))
1717 else_store
= DR_STMT (else_dr
);
1718 else_lhs
= gimple_get_lhs (else_store
);
1719 if (else_lhs
== NULL_TREE
)
1722 if (operand_equal_p (then_lhs
, else_lhs
, 0))
1732 then_stores
.safe_push (then_store
);
1733 else_stores
.safe_push (else_store
);
1736 /* No pairs of stores found. */
1737 if (!then_stores
.length ()
1738 || then_stores
.length () > (unsigned) MAX_STORES_TO_SINK
)
1740 free_data_refs (then_datarefs
);
1741 free_data_refs (else_datarefs
);
1745 /* Compute and check data dependencies in both basic blocks. */
1746 then_ddrs
.create (1);
1747 else_ddrs
.create (1);
1748 if (!compute_all_dependences (then_datarefs
, &then_ddrs
,
1750 || !compute_all_dependences (else_datarefs
, &else_ddrs
,
1753 free_dependence_relations (then_ddrs
);
1754 free_dependence_relations (else_ddrs
);
1755 free_data_refs (then_datarefs
);
1756 free_data_refs (else_datarefs
);
1759 blocks
[0] = then_bb
;
1760 blocks
[1] = else_bb
;
1761 blocks
[2] = join_bb
;
1762 renumber_gimple_stmt_uids_in_blocks (blocks
, 3);
1764 /* Check that there are no read-after-write or write-after-write dependencies
1766 FOR_EACH_VEC_ELT (then_ddrs
, i
, ddr
)
1768 struct data_reference
*dra
= DDR_A (ddr
);
1769 struct data_reference
*drb
= DDR_B (ddr
);
1771 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1772 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1773 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1774 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1775 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1776 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1778 free_dependence_relations (then_ddrs
);
1779 free_dependence_relations (else_ddrs
);
1780 free_data_refs (then_datarefs
);
1781 free_data_refs (else_datarefs
);
1786 /* Check that there are no read-after-write or write-after-write dependencies
1788 FOR_EACH_VEC_ELT (else_ddrs
, i
, ddr
)
1790 struct data_reference
*dra
= DDR_A (ddr
);
1791 struct data_reference
*drb
= DDR_B (ddr
);
1793 if (DDR_ARE_DEPENDENT (ddr
) != chrec_known
1794 && ((DR_IS_READ (dra
) && DR_IS_WRITE (drb
)
1795 && gimple_uid (DR_STMT (dra
)) > gimple_uid (DR_STMT (drb
)))
1796 || (DR_IS_READ (drb
) && DR_IS_WRITE (dra
)
1797 && gimple_uid (DR_STMT (drb
)) > gimple_uid (DR_STMT (dra
)))
1798 || (DR_IS_WRITE (dra
) && DR_IS_WRITE (drb
))))
1800 free_dependence_relations (then_ddrs
);
1801 free_dependence_relations (else_ddrs
);
1802 free_data_refs (then_datarefs
);
1803 free_data_refs (else_datarefs
);
1808 /* Sink stores with same LHS. */
1809 FOR_EACH_VEC_ELT (then_stores
, i
, then_store
)
1811 else_store
= else_stores
[i
];
1812 res
= cond_if_else_store_replacement_1 (then_bb
, else_bb
, join_bb
,
1813 then_store
, else_store
);
1817 free_dependence_relations (then_ddrs
);
1818 free_dependence_relations (else_ddrs
);
1819 free_data_refs (then_datarefs
);
1820 free_data_refs (else_datarefs
);
1825 /* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
1828 local_mem_dependence (gimple stmt
, basic_block bb
)
1830 tree vuse
= gimple_vuse (stmt
);
1836 def
= SSA_NAME_DEF_STMT (vuse
);
1837 return (def
&& gimple_bb (def
) == bb
);
1840 /* Given a "diamond" control-flow pattern where BB0 tests a condition,
1841 BB1 and BB2 are "then" and "else" blocks dependent on this test,
1842 and BB3 rejoins control flow following BB1 and BB2, look for
1843 opportunities to hoist loads as follows. If BB3 contains a PHI of
1844 two loads, one each occurring in BB1 and BB2, and the loads are
1845 provably of adjacent fields in the same structure, then move both
1846 loads into BB0. Of course this can only be done if there are no
1847 dependencies preventing such motion.
1849 One of the hoisted loads will always be speculative, so the
1850 transformation is currently conservative:
1852 - The fields must be strictly adjacent.
1853 - The two fields must occupy a single memory block that is
1854 guaranteed to not cross a page boundary.
1856 The last is difficult to prove, as such memory blocks should be
1857 aligned on the minimum of the stack alignment boundary and the
1858 alignment guaranteed by heap allocation interfaces. Thus we rely
1859 on a parameter for the alignment value.
1861 Provided a good value is used for the last case, the first
1862 restriction could possibly be relaxed. */
1865 hoist_adjacent_loads (basic_block bb0
, basic_block bb1
,
1866 basic_block bb2
, basic_block bb3
)
1868 int param_align
= PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
);
1869 unsigned param_align_bits
= (unsigned) (param_align
* BITS_PER_UNIT
);
1872 /* Walk the phis in bb3 looking for an opportunity. We are looking
1873 for phis of two SSA names, one each of which is defined in bb1 and
1875 for (gsi
= gsi_start_phis (bb3
); !gsi_end_p (gsi
); gsi_next (&gsi
))
1877 gphi
*phi_stmt
= gsi
.phi ();
1879 tree arg1
, arg2
, ref1
, ref2
, field1
, field2
;
1880 tree tree_offset1
, tree_offset2
, tree_size2
, next
;
1881 int offset1
, offset2
, size2
;
1883 gimple_stmt_iterator gsi2
;
1884 basic_block bb_for_def1
, bb_for_def2
;
1886 if (gimple_phi_num_args (phi_stmt
) != 2
1887 || virtual_operand_p (gimple_phi_result (phi_stmt
)))
1890 arg1
= gimple_phi_arg_def (phi_stmt
, 0);
1891 arg2
= gimple_phi_arg_def (phi_stmt
, 1);
1893 if (TREE_CODE (arg1
) != SSA_NAME
1894 || TREE_CODE (arg2
) != SSA_NAME
1895 || SSA_NAME_IS_DEFAULT_DEF (arg1
)
1896 || SSA_NAME_IS_DEFAULT_DEF (arg2
))
1899 def1
= SSA_NAME_DEF_STMT (arg1
);
1900 def2
= SSA_NAME_DEF_STMT (arg2
);
1902 if ((gimple_bb (def1
) != bb1
|| gimple_bb (def2
) != bb2
)
1903 && (gimple_bb (def2
) != bb1
|| gimple_bb (def1
) != bb2
))
1906 /* Check the mode of the arguments to be sure a conditional move
1907 can be generated for it. */
1908 if (optab_handler (movcc_optab
, TYPE_MODE (TREE_TYPE (arg1
)))
1909 == CODE_FOR_nothing
)
1912 /* Both statements must be assignments whose RHS is a COMPONENT_REF. */
1913 if (!gimple_assign_single_p (def1
)
1914 || !gimple_assign_single_p (def2
)
1915 || gimple_has_volatile_ops (def1
)
1916 || gimple_has_volatile_ops (def2
))
1919 ref1
= gimple_assign_rhs1 (def1
);
1920 ref2
= gimple_assign_rhs1 (def2
);
1922 if (TREE_CODE (ref1
) != COMPONENT_REF
1923 || TREE_CODE (ref2
) != COMPONENT_REF
)
1926 /* The zeroth operand of the two component references must be
1927 identical. It is not sufficient to compare get_base_address of
1928 the two references, because this could allow for different
1929 elements of the same array in the two trees. It is not safe to
1930 assume that the existence of one array element implies the
1931 existence of a different one. */
1932 if (!operand_equal_p (TREE_OPERAND (ref1
, 0), TREE_OPERAND (ref2
, 0), 0))
1935 field1
= TREE_OPERAND (ref1
, 1);
1936 field2
= TREE_OPERAND (ref2
, 1);
1938 /* Check for field adjacency, and ensure field1 comes first. */
1939 for (next
= DECL_CHAIN (field1
);
1940 next
&& TREE_CODE (next
) != FIELD_DECL
;
1941 next
= DECL_CHAIN (next
))
1946 for (next
= DECL_CHAIN (field2
);
1947 next
&& TREE_CODE (next
) != FIELD_DECL
;
1948 next
= DECL_CHAIN (next
))
1954 std::swap (field1
, field2
);
1955 std::swap (def1
, def2
);
1958 bb_for_def1
= gimple_bb (def1
);
1959 bb_for_def2
= gimple_bb (def2
);
1961 /* Check for proper alignment of the first field. */
1962 tree_offset1
= bit_position (field1
);
1963 tree_offset2
= bit_position (field2
);
1964 tree_size2
= DECL_SIZE (field2
);
1966 if (!tree_fits_uhwi_p (tree_offset1
)
1967 || !tree_fits_uhwi_p (tree_offset2
)
1968 || !tree_fits_uhwi_p (tree_size2
))
1971 offset1
= tree_to_uhwi (tree_offset1
);
1972 offset2
= tree_to_uhwi (tree_offset2
);
1973 size2
= tree_to_uhwi (tree_size2
);
1974 align1
= DECL_ALIGN (field1
) % param_align_bits
;
1976 if (offset1
% BITS_PER_UNIT
!= 0)
1979 /* For profitability, the two field references should fit within
1980 a single cache line. */
1981 if (align1
+ offset2
- offset1
+ size2
> param_align_bits
)
1984 /* The two expressions cannot be dependent upon vdefs defined
1986 if (local_mem_dependence (def1
, bb_for_def1
)
1987 || local_mem_dependence (def2
, bb_for_def2
))
1990 /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
1991 bb0. We hoist the first one first so that a cache miss is handled
1992 efficiently regardless of hardware cache-fill policy. */
1993 gsi2
= gsi_for_stmt (def1
);
1994 gsi_move_to_bb_end (&gsi2
, bb0
);
1995 gsi2
= gsi_for_stmt (def2
);
1996 gsi_move_to_bb_end (&gsi2
, bb0
);
1998 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2001 "\nHoisting adjacent loads from %d and %d into %d: \n",
2002 bb_for_def1
->index
, bb_for_def2
->index
, bb0
->index
);
2003 print_gimple_stmt (dump_file
, def1
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2004 print_gimple_stmt (dump_file
, def2
, 0, TDF_VOPS
|TDF_MEMSYMS
);
2009 /* Determine whether we should attempt to hoist adjacent loads out of
2010 diamond patterns in pass_phiopt. Always hoist loads if
2011 -fhoist-adjacent-loads is specified and the target machine has
2012 both a conditional move instruction and a defined cache line size. */
2015 gate_hoist_loads (void)
2017 return (flag_hoist_adjacent_loads
== 1
2018 && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE
)
2019 && HAVE_conditional_move
);
2022 /* This pass tries to replaces an if-then-else block with an
2023 assignment. We have four kinds of transformations. Some of these
2024 transformations are also performed by the ifcvt RTL optimizer.
2026 Conditional Replacement
2027 -----------------------
2029 This transformation, implemented in conditional_replacement,
2033 if (cond) goto bb2; else goto bb1;
2036 x = PHI <0 (bb1), 1 (bb0), ...>;
2044 x = PHI <x' (bb0), ...>;
2046 We remove bb1 as it becomes unreachable. This occurs often due to
2047 gimplification of conditionals.
2052 This transformation, implemented in value_replacement, replaces
2055 if (a != b) goto bb2; else goto bb1;
2058 x = PHI <a (bb1), b (bb0), ...>;
2064 x = PHI <b (bb0), ...>;
2066 This opportunity can sometimes occur as a result of other
2070 Another case caught by value replacement looks like this:
2076 if (t3 != 0) goto bb1; else goto bb2;
2092 This transformation, implemented in abs_replacement, replaces
2095 if (a >= 0) goto bb2; else goto bb1;
2099 x = PHI <x (bb1), a (bb0), ...>;
2106 x = PHI <x' (bb0), ...>;
2111 This transformation, minmax_replacement replaces
2114 if (a <= b) goto bb2; else goto bb1;
2117 x = PHI <b (bb1), a (bb0), ...>;
2122 x' = MIN_EXPR (a, b)
2124 x = PHI <x' (bb0), ...>;
2126 A similar transformation is done for MAX_EXPR.
2129 This pass also performs a fifth transformation of a slightly different
2132 Adjacent Load Hoisting
2133 ----------------------
2135 This transformation replaces
2138 if (...) goto bb2; else goto bb1;
2140 x1 = (<expr>).field1;
2143 x2 = (<expr>).field2;
2150 x1 = (<expr>).field1;
2151 x2 = (<expr>).field2;
2152 if (...) goto bb2; else goto bb1;
2159 The purpose of this transformation is to enable generation of conditional
2160 move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
2161 the loads is speculative, the transformation is restricted to very
2162 specific cases to avoid introducing a page fault. We are looking for
2170 where left and right are typically adjacent pointers in a tree structure. */
2174 const pass_data pass_data_phiopt
=
2176 GIMPLE_PASS
, /* type */
2177 "phiopt", /* name */
2178 OPTGROUP_NONE
, /* optinfo_flags */
2179 TV_TREE_PHIOPT
, /* tv_id */
2180 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2181 0, /* properties_provided */
2182 0, /* properties_destroyed */
2183 0, /* todo_flags_start */
2184 0, /* todo_flags_finish */
2187 class pass_phiopt
: public gimple_opt_pass
2190 pass_phiopt (gcc::context
*ctxt
)
2191 : gimple_opt_pass (pass_data_phiopt
, ctxt
)
2194 /* opt_pass methods: */
2195 opt_pass
* clone () { return new pass_phiopt (m_ctxt
); }
2196 virtual bool gate (function
*) { return flag_ssa_phiopt
; }
2197 virtual unsigned int execute (function
*)
2199 return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
2202 }; // class pass_phiopt
2207 make_pass_phiopt (gcc::context
*ctxt
)
2209 return new pass_phiopt (ctxt
);
2214 const pass_data pass_data_cselim
=
2216 GIMPLE_PASS
, /* type */
2217 "cselim", /* name */
2218 OPTGROUP_NONE
, /* optinfo_flags */
2219 TV_TREE_PHIOPT
, /* tv_id */
2220 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2221 0, /* properties_provided */
2222 0, /* properties_destroyed */
2223 0, /* todo_flags_start */
2224 0, /* todo_flags_finish */
2227 class pass_cselim
: public gimple_opt_pass
2230 pass_cselim (gcc::context
*ctxt
)
2231 : gimple_opt_pass (pass_data_cselim
, ctxt
)
2234 /* opt_pass methods: */
2235 virtual bool gate (function
*) { return flag_tree_cselim
; }
2236 virtual unsigned int execute (function
*) { return tree_ssa_cs_elim (); }
2238 }; // class pass_cselim
2243 make_pass_cselim (gcc::context
*ctxt
)
2245 return new pass_cselim (ctxt
);