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"
23 #include "hash-table.h"
28 #include "double-int.h"
35 #include "fold-const.h"
36 #include "stor-layout.h"
40 #include "hard-reg-set.h"
42 #include "dominance.h"
45 #include "basic-block.h"
46 #include "tree-ssa-alias.h"
47 #include "internal-fn.h"
48 #include "gimple-expr.h"
52 #include "gimple-iterator.h"
53 #include "gimplify-me.h"
54 #include "gimple-ssa.h"
56 #include "tree-phinodes.h"
57 #include "ssa-iterators.h"
58 #include "stringpool.h"
59 #include "tree-ssanames.h"
62 #include "statistics.h"
64 #include "fixed-value.h"
65 #include "insn-config.h"
75 #include "tree-pass.h"
76 #include "langhooks.h"
79 #include "tree-data-ref.h"
80 #include "gimple-pretty-print.h"
81 #include "insn-codes.h"
83 #include "tree-scalar-evolution.h"
84 #include "tree-inline.h"
86 #ifndef HAVE_conditional_move
87 #define HAVE_conditional_move (0)
90 static unsigned int tree_ssa_phiopt_worker (bool, bool);
91 static bool conditional_replacement (basic_block, basic_block,
92 edge, edge, gphi *, tree, tree);
93 static int value_replacement (basic_block, basic_block,
94 edge, edge, gimple, tree, tree);
95 static bool minmax_replacement (basic_block, basic_block,
96 edge, edge, gimple, tree, tree);
97 static bool abs_replacement (basic_block, basic_block,
98 edge, edge, gimple, tree, tree);
99 static bool cond_store_replacement (basic_block, basic_block, edge, edge,
101 static bool cond_if_else_store_replacement (basic_block, basic_block, basic_block);
102 static hash_set<tree> * get_non_trapping ();
103 static void replace_phi_edge_with_variable (basic_block, edge, gimple, tree);
104 static void hoist_adjacent_loads (basic_block, basic_block,
105 basic_block, basic_block);
106 static bool gate_hoist_loads (void);
108 /* This pass tries to transform conditional stores into unconditional
109 ones, enabling further simplifications with the simpler then and else
110 blocks. In particular it replaces this:
113 if (cond) goto bb2; else goto bb1;
121 if (cond) goto bb1; else goto bb2;
125 condtmp = PHI <RHS, condtmp'>
128 This transformation can only be done under several constraints,
129 documented below. It also replaces:
132 if (cond) goto bb2; else goto bb1;
143 if (cond) goto bb3; else goto bb1;
146 condtmp = PHI <RHS1, RHS2>
150 tree_ssa_cs_elim (void)
153 /* ??? We are not interested in loop related info, but the following
154 will create it, ICEing as we didn't init loops with pre-headers.
155 An interfacing issue of find_data_references_in_bb. */
156 loop_optimizer_init (LOOPS_NORMAL);
158 todo = tree_ssa_phiopt_worker (true, false);
160 loop_optimizer_finalize ();
164 /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
167 single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1)
169 gimple_stmt_iterator i;
171 if (gimple_seq_singleton_p (seq))
172 return as_a <gphi *> (gsi_stmt (gsi_start (seq)));
173 for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
175 gphi *p = as_a <gphi *> (gsi_stmt (i));
176 /* If the PHI arguments are equal then we can skip this PHI. */
177 if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p, e0->dest_idx),
178 gimple_phi_arg_def (p, e1->dest_idx)))
181 /* If we already have a PHI that has the two edge arguments are
182 different, then return it is not a singleton for these PHIs. */
191 /* The core routine of conditional store replacement and normal
192 phi optimizations. Both share much of the infrastructure in how
193 to match applicable basic block patterns. DO_STORE_ELIM is true
194 when we want to do conditional store replacement, false otherwise.
195 DO_HOIST_LOADS is true when we want to hoist adjacent loads out
196 of diamond control flow patterns, false otherwise. */
198 tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads)
201 basic_block *bb_order;
203 bool cfgchanged = false;
204 hash_set<tree> *nontrap = 0;
207 /* Calculate the set of non-trapping memory accesses. */
208 nontrap = get_non_trapping ();
210 /* Search every basic block for COND_EXPR we may be able to optimize.
212 We walk the blocks in order that guarantees that a block with
213 a single predecessor is processed before the predecessor.
214 This ensures that we collapse inner ifs before visiting the
215 outer ones, and also that we do not try to visit a removed
217 bb_order = single_pred_before_succ_order ();
218 n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS;
220 for (i = 0; i < n; i++)
224 basic_block bb1, bb2;
230 cond_stmt = last_stmt (bb);
231 /* Check to see if the last statement is a GIMPLE_COND. */
233 || gimple_code (cond_stmt) != GIMPLE_COND)
236 e1 = EDGE_SUCC (bb, 0);
238 e2 = EDGE_SUCC (bb, 1);
241 /* We cannot do the optimization on abnormal edges. */
242 if ((e1->flags & EDGE_ABNORMAL) != 0
243 || (e2->flags & EDGE_ABNORMAL) != 0)
246 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
247 if (EDGE_COUNT (bb1->succs) == 0
249 || EDGE_COUNT (bb2->succs) == 0)
252 /* Find the bb which is the fall through to the other. */
253 if (EDGE_SUCC (bb1, 0)->dest == bb2)
255 else if (EDGE_SUCC (bb2, 0)->dest == bb1)
257 basic_block bb_tmp = bb1;
264 else if (do_store_elim
265 && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
267 basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
269 if (!single_succ_p (bb1)
270 || (EDGE_SUCC (bb1, 0)->flags & EDGE_FALLTHRU) == 0
271 || !single_succ_p (bb2)
272 || (EDGE_SUCC (bb2, 0)->flags & EDGE_FALLTHRU) == 0
273 || EDGE_COUNT (bb3->preds) != 2)
275 if (cond_if_else_store_replacement (bb1, bb2, bb3))
279 else if (do_hoist_loads
280 && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
282 basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
284 if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt)))
285 && single_succ_p (bb1)
286 && single_succ_p (bb2)
287 && single_pred_p (bb1)
288 && single_pred_p (bb2)
289 && EDGE_COUNT (bb->succs) == 2
290 && EDGE_COUNT (bb3->preds) == 2
291 /* If one edge or the other is dominant, a conditional move
292 is likely to perform worse than the well-predicted branch. */
293 && !predictable_edge_p (EDGE_SUCC (bb, 0))
294 && !predictable_edge_p (EDGE_SUCC (bb, 1)))
295 hoist_adjacent_loads (bb, bb1, bb2, bb3);
301 e1 = EDGE_SUCC (bb1, 0);
303 /* Make sure that bb1 is just a fall through. */
304 if (!single_succ_p (bb1)
305 || (e1->flags & EDGE_FALLTHRU) == 0)
308 /* Also make sure that bb1 only have one predecessor and that it
310 if (!single_pred_p (bb1)
311 || single_pred (bb1) != bb)
316 /* bb1 is the middle block, bb2 the join block, bb the split block,
317 e1 the fallthrough edge from bb1 to bb2. We can't do the
318 optimization if the join block has more than two predecessors. */
319 if (EDGE_COUNT (bb2->preds) > 2)
321 if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
326 gimple_seq phis = phi_nodes (bb2);
327 gimple_stmt_iterator gsi;
328 bool candorest = true;
330 /* Value replacement can work with more than one PHI
331 so try that first. */
332 for (gsi = gsi_start (phis); !gsi_end_p (gsi); gsi_next (&gsi))
334 phi = as_a <gphi *> (gsi_stmt (gsi));
335 arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
336 arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
337 if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1) == 2)
348 phi = single_non_singleton_phi_for_edges (phis, e1, e2);
352 arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
353 arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
355 /* Something is wrong if we cannot find the arguments in the PHI
357 gcc_assert (arg0 != NULL && arg1 != NULL);
359 /* Do the replacement of conditional if it can be done. */
360 if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
362 else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
364 else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
373 /* If the CFG has changed, we should cleanup the CFG. */
374 if (cfgchanged && do_store_elim)
376 /* In cond-store replacement we have added some loads on edges
377 and new VOPS (as we moved the store, and created a load). */
378 gsi_commit_edge_inserts ();
379 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
382 return TODO_cleanup_cfg;
386 /* Replace PHI node element whose edge is E in block BB with variable NEW.
387 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
388 is known to have two edges, one of which must reach BB). */
391 replace_phi_edge_with_variable (basic_block cond_block,
392 edge e, gimple phi, tree new_tree)
394 basic_block bb = gimple_bb (phi);
395 basic_block block_to_remove;
396 gimple_stmt_iterator gsi;
398 /* Change the PHI argument to new. */
399 SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
401 /* Remove the empty basic block. */
402 if (EDGE_SUCC (cond_block, 0)->dest == bb)
404 EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;
405 EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
406 EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE;
407 EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count;
409 block_to_remove = EDGE_SUCC (cond_block, 1)->dest;
413 EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;
414 EDGE_SUCC (cond_block, 1)->flags
415 &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
416 EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE;
417 EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count;
419 block_to_remove = EDGE_SUCC (cond_block, 0)->dest;
421 delete_basic_block (block_to_remove);
423 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
424 gsi = gsi_last_bb (cond_block);
425 gsi_remove (&gsi, true);
427 if (dump_file && (dump_flags & TDF_DETAILS))
429 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
434 /* The function conditional_replacement does the main work of doing the
435 conditional replacement. Return true if the replacement is done.
436 Otherwise return false.
437 BB is the basic block where the replacement is going to be done on. ARG0
438 is argument 0 from PHI. Likewise for ARG1. */
441 conditional_replacement (basic_block cond_bb, basic_block middle_bb,
442 edge e0, edge e1, gphi *phi,
443 tree arg0, tree arg1)
449 gimple_stmt_iterator gsi;
450 edge true_edge, false_edge;
451 tree new_var, new_var2;
454 /* FIXME: Gimplification of complex type is too hard for now. */
455 /* We aren't prepared to handle vectors either (and it is a question
456 if it would be worthwhile anyway). */
457 if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0))
458 || POINTER_TYPE_P (TREE_TYPE (arg0)))
459 || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1))
460 || POINTER_TYPE_P (TREE_TYPE (arg1))))
463 /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
464 convert it to the conditional. */
465 if ((integer_zerop (arg0) && integer_onep (arg1))
466 || (integer_zerop (arg1) && integer_onep (arg0)))
468 else if ((integer_zerop (arg0) && integer_all_onesp (arg1))
469 || (integer_zerop (arg1) && integer_all_onesp (arg0)))
474 if (!empty_block_p (middle_bb))
477 /* At this point we know we have a GIMPLE_COND with two successors.
478 One successor is BB, the other successor is an empty block which
479 falls through into BB.
481 There is a single PHI node at the join point (BB) and its arguments
482 are constants (0, 1) or (0, -1).
484 So, given the condition COND, and the two PHI arguments, we can
485 rewrite this PHI into non-branching code:
487 dest = (COND) or dest = COND'
489 We use the condition as-is if the argument associated with the
490 true edge has the value one or the argument associated with the
491 false edge as the value zero. Note that those conditions are not
492 the same since only one of the outgoing edges from the GIMPLE_COND
493 will directly reach BB and thus be associated with an argument. */
495 stmt = last_stmt (cond_bb);
496 result = PHI_RESULT (phi);
498 /* To handle special cases like floating point comparison, it is easier and
499 less error-prone to build a tree and gimplify it on the fly though it is
501 cond = fold_build2_loc (gimple_location (stmt),
502 gimple_cond_code (stmt), boolean_type_node,
503 gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
505 /* We need to know which is the true edge and which is the false
506 edge so that we know when to invert the condition below. */
507 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
508 if ((e0 == true_edge && integer_zerop (arg0))
509 || (e0 == false_edge && !integer_zerop (arg0))
510 || (e1 == true_edge && integer_zerop (arg1))
511 || (e1 == false_edge && !integer_zerop (arg1)))
512 cond = fold_build1_loc (gimple_location (stmt),
513 TRUTH_NOT_EXPR, TREE_TYPE (cond), cond);
517 cond = fold_convert_loc (gimple_location (stmt),
518 TREE_TYPE (result), cond);
519 cond = fold_build1_loc (gimple_location (stmt),
520 NEGATE_EXPR, TREE_TYPE (cond), cond);
523 /* Insert our new statements at the end of conditional block before the
525 gsi = gsi_for_stmt (stmt);
526 new_var = force_gimple_operand_gsi (&gsi, cond, true, NULL, true,
529 if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (new_var)))
531 source_location locus_0, locus_1;
533 new_var2 = make_ssa_name (TREE_TYPE (result));
534 new_stmt = gimple_build_assign (new_var2, CONVERT_EXPR, new_var);
535 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
538 /* Set the locus to the first argument, unless is doesn't have one. */
539 locus_0 = gimple_phi_arg_location (phi, 0);
540 locus_1 = gimple_phi_arg_location (phi, 1);
541 if (locus_0 == UNKNOWN_LOCATION)
543 gimple_set_location (new_stmt, locus_0);
546 replace_phi_edge_with_variable (cond_bb, e1, phi, new_var);
547 reset_flow_sensitive_info_in_bb (cond_bb);
549 /* Note that we optimized this PHI. */
553 /* Update *ARG which is defined in STMT so that it contains the
554 computed value if that seems profitable. Return true if the
555 statement is made dead by that rewriting. */
558 jump_function_from_stmt (tree *arg, gimple stmt)
560 enum tree_code code = gimple_assign_rhs_code (stmt);
561 if (code == ADDR_EXPR)
563 /* For arg = &p->i transform it to p, if possible. */
564 tree rhs1 = gimple_assign_rhs1 (stmt);
565 HOST_WIDE_INT offset;
566 tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs1, 0),
569 && TREE_CODE (tem) == MEM_REF
570 && (mem_ref_offset (tem) + offset) == 0)
572 *arg = TREE_OPERAND (tem, 0);
576 /* TODO: Much like IPA-CP jump-functions we want to handle constant
577 additions symbolically here, and we'd need to update the comparison
578 code that compares the arg + cst tuples in our caller. For now the
579 code above exactly handles the VEC_BASE pattern from vec.h. */
583 /* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
584 of the form SSA_NAME NE 0.
586 If RHS is fed by a simple EQ_EXPR comparison of two values, see if
587 the two input values of the EQ_EXPR match arg0 and arg1.
589 If so update *code and return TRUE. Otherwise return FALSE. */
592 rhs_is_fed_for_value_replacement (const_tree arg0, const_tree arg1,
593 enum tree_code *code, const_tree rhs)
595 /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
597 if (TREE_CODE (rhs) == SSA_NAME)
599 gimple def1 = SSA_NAME_DEF_STMT (rhs);
601 /* Verify the defining statement has an EQ_EXPR on the RHS. */
602 if (is_gimple_assign (def1) && gimple_assign_rhs_code (def1) == EQ_EXPR)
604 /* Finally verify the source operands of the EQ_EXPR are equal
606 tree op0 = gimple_assign_rhs1 (def1);
607 tree op1 = gimple_assign_rhs2 (def1);
608 if ((operand_equal_for_phi_arg_p (arg0, op0)
609 && operand_equal_for_phi_arg_p (arg1, op1))
610 || (operand_equal_for_phi_arg_p (arg0, op1)
611 && operand_equal_for_phi_arg_p (arg1, op0)))
613 /* We will perform the optimization. */
614 *code = gimple_assign_rhs_code (def1);
622 /* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND.
624 Also return TRUE if arg0/arg1 are equal to the source arguments of a
625 an EQ comparison feeding a BIT_AND_EXPR which feeds COND.
627 Return FALSE otherwise. */
630 operand_equal_for_value_replacement (const_tree arg0, const_tree arg1,
631 enum tree_code *code, gimple cond)
634 tree lhs = gimple_cond_lhs (cond);
635 tree rhs = gimple_cond_rhs (cond);
637 if ((operand_equal_for_phi_arg_p (arg0, lhs)
638 && operand_equal_for_phi_arg_p (arg1, rhs))
639 || (operand_equal_for_phi_arg_p (arg1, lhs)
640 && operand_equal_for_phi_arg_p (arg0, rhs)))
643 /* Now handle more complex case where we have an EQ comparison
644 which feeds a BIT_AND_EXPR which feeds COND.
646 First verify that COND is of the form SSA_NAME NE 0. */
647 if (*code != NE_EXPR || !integer_zerop (rhs)
648 || TREE_CODE (lhs) != SSA_NAME)
651 /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */
652 def = SSA_NAME_DEF_STMT (lhs);
653 if (!is_gimple_assign (def) || gimple_assign_rhs_code (def) != BIT_AND_EXPR)
656 /* Now verify arg0/arg1 correspond to the source arguments of an
657 EQ comparison feeding the BIT_AND_EXPR. */
659 tree tmp = gimple_assign_rhs1 (def);
660 if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
663 tmp = gimple_assign_rhs2 (def);
664 if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
670 /* Returns true if ARG is a neutral element for operation CODE
671 on the RIGHT side. */
674 neutral_element_p (tree_code code, tree arg, bool right)
681 return integer_zerop (arg);
688 case POINTER_PLUS_EXPR:
689 return right && integer_zerop (arg);
692 return integer_onep (arg);
699 return right && integer_onep (arg);
702 return integer_all_onesp (arg);
709 /* Returns true if ARG is an absorbing element for operation CODE. */
712 absorbing_element_p (tree_code code, tree arg)
717 return integer_all_onesp (arg);
721 return integer_zerop (arg);
728 /* The function value_replacement does the main work of doing the value
729 replacement. Return non-zero if the replacement is done. Otherwise return
730 0. If we remove the middle basic block, return 2.
731 BB is the basic block where the replacement is going to be done on. ARG0
732 is argument 0 from the PHI. Likewise for ARG1. */
735 value_replacement (basic_block cond_bb, basic_block middle_bb,
736 edge e0, edge e1, gimple phi,
737 tree arg0, tree arg1)
739 gimple_stmt_iterator gsi;
741 edge true_edge, false_edge;
743 bool emtpy_or_with_defined_p = true;
745 /* If the type says honor signed zeros we cannot do this
747 if (HONOR_SIGNED_ZEROS (arg1))
750 /* If there is a statement in MIDDLE_BB that defines one of the PHI
751 arguments, then adjust arg0 or arg1. */
752 gsi = gsi_start_nondebug_after_labels_bb (middle_bb);
753 while (!gsi_end_p (gsi))
755 gimple stmt = gsi_stmt (gsi);
757 gsi_next_nondebug (&gsi);
758 if (!is_gimple_assign (stmt))
760 emtpy_or_with_defined_p = false;
763 /* Now try to adjust arg0 or arg1 according to the computation
765 lhs = gimple_assign_lhs (stmt);
767 && jump_function_from_stmt (&arg0, stmt))
769 && jump_function_from_stmt (&arg1, stmt)))
770 emtpy_or_with_defined_p = false;
773 cond = last_stmt (cond_bb);
774 code = gimple_cond_code (cond);
776 /* This transformation is only valid for equality comparisons. */
777 if (code != NE_EXPR && code != EQ_EXPR)
780 /* We need to know which is the true edge and which is the false
781 edge so that we know if have abs or negative abs. */
782 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
784 /* At this point we know we have a COND_EXPR with two successors.
785 One successor is BB, the other successor is an empty block which
786 falls through into BB.
788 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
790 There is a single PHI node at the join point (BB) with two arguments.
792 We now need to verify that the two arguments in the PHI node match
793 the two arguments to the equality comparison. */
795 if (operand_equal_for_value_replacement (arg0, arg1, &code, cond))
800 /* For NE_EXPR, we want to build an assignment result = arg where
801 arg is the PHI argument associated with the true edge. For
802 EQ_EXPR we want the PHI argument associated with the false edge. */
803 e = (code == NE_EXPR ? true_edge : false_edge);
805 /* Unfortunately, E may not reach BB (it may instead have gone to
806 OTHER_BLOCK). If that is the case, then we want the single outgoing
807 edge from OTHER_BLOCK which reaches BB and represents the desired
808 path from COND_BLOCK. */
809 if (e->dest == middle_bb)
810 e = single_succ_edge (e->dest);
812 /* Now we know the incoming edge to BB that has the argument for the
813 RHS of our new assignment statement. */
819 /* If the middle basic block was empty or is defining the
820 PHI arguments and this is a single phi where the args are different
821 for the edges e0 and e1 then we can remove the middle basic block. */
822 if (emtpy_or_with_defined_p
823 && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)),
826 replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
827 /* Note that we optimized this PHI. */
832 /* Replace the PHI arguments with arg. */
833 SET_PHI_ARG_DEF (phi, e0->dest_idx, arg);
834 SET_PHI_ARG_DEF (phi, e1->dest_idx, arg);
835 if (dump_file && (dump_flags & TDF_DETAILS))
837 fprintf (dump_file, "PHI ");
838 print_generic_expr (dump_file, gimple_phi_result (phi), 0);
839 fprintf (dump_file, " reduced for COND_EXPR in block %d to ",
841 print_generic_expr (dump_file, arg, 0);
842 fprintf (dump_file, ".\n");
849 /* Now optimize (x != 0) ? x + y : y to just y.
850 The following condition is too restrictive, there can easily be another
851 stmt in middle_bb, for instance a CONVERT_EXPR for the second argument. */
852 gimple assign = last_and_only_stmt (middle_bb);
853 if (!assign || gimple_code (assign) != GIMPLE_ASSIGN
854 || gimple_assign_rhs_class (assign) != GIMPLE_BINARY_RHS
855 || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0))
856 && !POINTER_TYPE_P (TREE_TYPE (arg0))))
859 /* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */
860 if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
863 /* Only transform if it removes the condition. */
864 if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)), e0, e1))
867 /* Size-wise, this is always profitable. */
868 if (optimize_bb_for_speed_p (cond_bb)
869 /* The special case is useless if it has a low probability. */
870 && profile_status_for_fn (cfun) != PROFILE_ABSENT
871 && EDGE_PRED (middle_bb, 0)->probability < PROB_EVEN
872 /* If assign is cheap, there is no point avoiding it. */
873 && estimate_num_insns (assign, &eni_time_weights)
874 >= 3 * estimate_num_insns (cond, &eni_time_weights))
877 tree lhs = gimple_assign_lhs (assign);
878 tree rhs1 = gimple_assign_rhs1 (assign);
879 tree rhs2 = gimple_assign_rhs2 (assign);
880 enum tree_code code_def = gimple_assign_rhs_code (assign);
881 tree cond_lhs = gimple_cond_lhs (cond);
882 tree cond_rhs = gimple_cond_rhs (cond);
884 if (((code == NE_EXPR && e1 == false_edge)
885 || (code == EQ_EXPR && e1 == true_edge))
888 && operand_equal_for_phi_arg_p (rhs2, cond_lhs)
889 && neutral_element_p (code_def, cond_rhs, true))
891 && operand_equal_for_phi_arg_p (rhs1, cond_lhs)
892 && neutral_element_p (code_def, cond_rhs, false))
893 || (operand_equal_for_phi_arg_p (arg1, cond_rhs)
894 && (operand_equal_for_phi_arg_p (rhs2, cond_lhs)
895 || operand_equal_for_phi_arg_p (rhs1, cond_lhs))
896 && absorbing_element_p (code_def, cond_rhs))))
898 gsi = gsi_for_stmt (cond);
899 if (INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
901 /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6
909 # RANGE [0, 4294967294]
910 u_6 = n_5 + 4294967295;
913 # u_3 = PHI <u_6(3), 4294967295(2)> */
914 SSA_NAME_RANGE_INFO (lhs) = NULL;
915 SSA_NAME_ANTI_RANGE_P (lhs) = 0;
916 /* If available, we can use VR of phi result at least. */
917 tree phires = gimple_phi_result (phi);
918 struct range_info_def *phires_range_info
919 = SSA_NAME_RANGE_INFO (phires);
920 if (phires_range_info)
921 duplicate_ssa_name_range_info (lhs, SSA_NAME_RANGE_TYPE (phires),
924 gimple_stmt_iterator gsi_from = gsi_for_stmt (assign);
925 gsi_move_before (&gsi_from, &gsi);
926 replace_phi_edge_with_variable (cond_bb, e1, phi, lhs);
933 /* The function minmax_replacement does the main work of doing the minmax
934 replacement. Return true if the replacement is done. Otherwise return
936 BB is the basic block where the replacement is going to be done on. ARG0
937 is argument 0 from the PHI. Likewise for ARG1. */
940 minmax_replacement (basic_block cond_bb, basic_block middle_bb,
941 edge e0, edge e1, gimple phi,
942 tree arg0, tree arg1)
947 edge true_edge, false_edge;
948 enum tree_code cmp, minmax, ass_code;
949 tree smaller, larger, arg_true, arg_false;
950 gimple_stmt_iterator gsi, gsi_from;
952 type = TREE_TYPE (PHI_RESULT (phi));
954 /* The optimization may be unsafe due to NaNs. */
955 if (HONOR_NANS (type))
958 cond = as_a <gcond *> (last_stmt (cond_bb));
959 cmp = gimple_cond_code (cond);
961 /* This transformation is only valid for order comparisons. Record which
962 operand is smaller/larger if the result of the comparison is true. */
963 if (cmp == LT_EXPR || cmp == LE_EXPR)
965 smaller = gimple_cond_lhs (cond);
966 larger = gimple_cond_rhs (cond);
968 else if (cmp == GT_EXPR || cmp == GE_EXPR)
970 smaller = gimple_cond_rhs (cond);
971 larger = gimple_cond_lhs (cond);
976 /* We need to know which is the true edge and which is the false
977 edge so that we know if have abs or negative abs. */
978 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
980 /* Forward the edges over the middle basic block. */
981 if (true_edge->dest == middle_bb)
982 true_edge = EDGE_SUCC (true_edge->dest, 0);
983 if (false_edge->dest == middle_bb)
984 false_edge = EDGE_SUCC (false_edge->dest, 0);
988 gcc_assert (false_edge == e1);
994 gcc_assert (false_edge == e0);
995 gcc_assert (true_edge == e1);
1000 if (empty_block_p (middle_bb))
1002 if (operand_equal_for_phi_arg_p (arg_true, smaller)
1003 && operand_equal_for_phi_arg_p (arg_false, larger))
1007 if (smaller < larger)
1013 else if (operand_equal_for_phi_arg_p (arg_false, smaller)
1014 && operand_equal_for_phi_arg_p (arg_true, larger))
1021 /* Recognize the following case, assuming d <= u:
1027 This is equivalent to
1032 gimple assign = last_and_only_stmt (middle_bb);
1033 tree lhs, op0, op1, bound;
1036 || gimple_code (assign) != GIMPLE_ASSIGN)
1039 lhs = gimple_assign_lhs (assign);
1040 ass_code = gimple_assign_rhs_code (assign);
1041 if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
1043 op0 = gimple_assign_rhs1 (assign);
1044 op1 = gimple_assign_rhs2 (assign);
1046 if (true_edge->src == middle_bb)
1048 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
1049 if (!operand_equal_for_phi_arg_p (lhs, arg_true))
1052 if (operand_equal_for_phi_arg_p (arg_false, larger))
1056 if (smaller < larger)
1058 r' = MAX_EXPR (smaller, bound)
1060 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
1061 if (ass_code != MAX_EXPR)
1065 if (operand_equal_for_phi_arg_p (op0, smaller))
1067 else if (operand_equal_for_phi_arg_p (op1, smaller))
1072 /* We need BOUND <= LARGER. */
1073 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
1077 else if (operand_equal_for_phi_arg_p (arg_false, smaller))
1081 if (smaller < larger)
1083 r' = MIN_EXPR (larger, bound)
1085 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
1086 if (ass_code != MIN_EXPR)
1090 if (operand_equal_for_phi_arg_p (op0, larger))
1092 else if (operand_equal_for_phi_arg_p (op1, larger))
1097 /* We need BOUND >= SMALLER. */
1098 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
1107 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
1108 if (!operand_equal_for_phi_arg_p (lhs, arg_false))
1111 if (operand_equal_for_phi_arg_p (arg_true, larger))
1115 if (smaller > larger)
1117 r' = MIN_EXPR (smaller, bound)
1119 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
1120 if (ass_code != MIN_EXPR)
1124 if (operand_equal_for_phi_arg_p (op0, smaller))
1126 else if (operand_equal_for_phi_arg_p (op1, smaller))
1131 /* We need BOUND >= LARGER. */
1132 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
1136 else if (operand_equal_for_phi_arg_p (arg_true, smaller))
1140 if (smaller > larger)
1142 r' = MAX_EXPR (larger, bound)
1144 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
1145 if (ass_code != MAX_EXPR)
1149 if (operand_equal_for_phi_arg_p (op0, larger))
1151 else if (operand_equal_for_phi_arg_p (op1, larger))
1156 /* We need BOUND <= SMALLER. */
1157 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
1165 /* Move the statement from the middle block. */
1166 gsi = gsi_last_bb (cond_bb);
1167 gsi_from = gsi_last_nondebug_bb (middle_bb);
1168 gsi_move_before (&gsi_from, &gsi);
1171 /* Emit the statement to compute min/max. */
1172 result = duplicate_ssa_name (PHI_RESULT (phi), NULL);
1173 new_stmt = gimple_build_assign (result, minmax, arg0, arg1);
1174 gsi = gsi_last_bb (cond_bb);
1175 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1177 replace_phi_edge_with_variable (cond_bb, e1, phi, result);
1178 reset_flow_sensitive_info_in_bb (cond_bb);
1183 /* The function absolute_replacement does the main work of doing the absolute
1184 replacement. Return true if the replacement is done. Otherwise return
1186 bb is the basic block where the replacement is going to be done on. arg0
1187 is argument 0 from the phi. Likewise for arg1. */
1190 abs_replacement (basic_block cond_bb, basic_block middle_bb,
1191 edge e0 ATTRIBUTE_UNUSED, edge e1,
1192 gimple phi, tree arg0, tree arg1)
1197 gimple_stmt_iterator gsi;
1198 edge true_edge, false_edge;
1203 enum tree_code cond_code;
1205 /* If the type says honor signed zeros we cannot do this
1207 if (HONOR_SIGNED_ZEROS (arg1))
1210 /* OTHER_BLOCK must have only one executable statement which must have the
1211 form arg0 = -arg1 or arg1 = -arg0. */
1213 assign = last_and_only_stmt (middle_bb);
1214 /* If we did not find the proper negation assignment, then we can not
1219 /* If we got here, then we have found the only executable statement
1220 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
1221 arg1 = -arg0, then we can not optimize. */
1222 if (gimple_code (assign) != GIMPLE_ASSIGN)
1225 lhs = gimple_assign_lhs (assign);
1227 if (gimple_assign_rhs_code (assign) != NEGATE_EXPR)
1230 rhs = gimple_assign_rhs1 (assign);
1232 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
1233 if (!(lhs == arg0 && rhs == arg1)
1234 && !(lhs == arg1 && rhs == arg0))
1237 cond = last_stmt (cond_bb);
1238 result = PHI_RESULT (phi);
1240 /* Only relationals comparing arg[01] against zero are interesting. */
1241 cond_code = gimple_cond_code (cond);
1242 if (cond_code != GT_EXPR && cond_code != GE_EXPR
1243 && cond_code != LT_EXPR && cond_code != LE_EXPR)
1246 /* Make sure the conditional is arg[01] OP y. */
1247 if (gimple_cond_lhs (cond) != rhs)
1250 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond)))
1251 ? real_zerop (gimple_cond_rhs (cond))
1252 : integer_zerop (gimple_cond_rhs (cond)))
1257 /* We need to know which is the true edge and which is the false
1258 edge so that we know if have abs or negative abs. */
1259 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
1261 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
1262 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
1263 the false edge goes to OTHER_BLOCK. */
1264 if (cond_code == GT_EXPR || cond_code == GE_EXPR)
1269 if (e->dest == middle_bb)
1274 result = duplicate_ssa_name (result, NULL);
1277 lhs = make_ssa_name (TREE_TYPE (result));
1281 /* Build the modify expression with abs expression. */
1282 new_stmt = gimple_build_assign (lhs, ABS_EXPR, rhs);
1284 gsi = gsi_last_bb (cond_bb);
1285 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1289 /* Get the right GSI. We want to insert after the recently
1290 added ABS_EXPR statement (which we know is the first statement
1292 new_stmt = gimple_build_assign (result, NEGATE_EXPR, lhs);
1294 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
1297 replace_phi_edge_with_variable (cond_bb, e1, phi, result);
1298 reset_flow_sensitive_info_in_bb (cond_bb);
1300 /* Note that we optimized this PHI. */
1304 /* Auxiliary functions to determine the set of memory accesses which
1305 can't trap because they are preceded by accesses to the same memory
1306 portion. We do that for MEM_REFs, so we only need to track
1307 the SSA_NAME of the pointer indirectly referenced. The algorithm
1308 simply is a walk over all instructions in dominator order. When
1309 we see an MEM_REF we determine if we've already seen a same
1310 ref anywhere up to the root of the dominator tree. If we do the
1311 current access can't trap. If we don't see any dominating access
1312 the current access might trap, but might also make later accesses
1313 non-trapping, so we remember it. We need to be careful with loads
1314 or stores, for instance a load might not trap, while a store would,
1315 so if we see a dominating read access this doesn't mean that a later
1316 write access would not trap. Hence we also need to differentiate the
1317 type of access(es) seen.
1319 ??? We currently are very conservative and assume that a load might
1320 trap even if a store doesn't (write-only memory). This probably is
1321 overly conservative. */
1323 /* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
1324 through it was seen, which would constitute a no-trap region for
1328 unsigned int ssa_name_ver;
1331 HOST_WIDE_INT offset, size;
1335 /* Hashtable helpers. */
1337 struct ssa_names_hasher : typed_free_remove <name_to_bb>
1339 typedef name_to_bb value_type;
1340 typedef name_to_bb compare_type;
1341 static inline hashval_t hash (const value_type *);
1342 static inline bool equal (const value_type *, const compare_type *);
1345 /* Used for quick clearing of the hash-table when we see calls.
1346 Hash entries with phase < nt_call_phase are invalid. */
1347 static unsigned int nt_call_phase;
1349 /* The hash function. */
1352 ssa_names_hasher::hash (const value_type *n)
1354 return n->ssa_name_ver ^ (((hashval_t) n->store) << 31)
1355 ^ (n->offset << 6) ^ (n->size << 3);
1358 /* The equality function of *P1 and *P2. */
1361 ssa_names_hasher::equal (const value_type *n1, const compare_type *n2)
1363 return n1->ssa_name_ver == n2->ssa_name_ver
1364 && n1->store == n2->store
1365 && n1->offset == n2->offset
1366 && n1->size == n2->size;
1369 class nontrapping_dom_walker : public dom_walker
1372 nontrapping_dom_walker (cdi_direction direction, hash_set<tree> *ps)
1373 : dom_walker (direction), m_nontrapping (ps), m_seen_ssa_names (128) {}
1375 virtual void before_dom_children (basic_block);
1376 virtual void after_dom_children (basic_block);
1380 /* We see the expression EXP in basic block BB. If it's an interesting
1381 expression (an MEM_REF through an SSA_NAME) possibly insert the
1382 expression into the set NONTRAP or the hash table of seen expressions.
1383 STORE is true if this expression is on the LHS, otherwise it's on
1385 void add_or_mark_expr (basic_block, tree, bool);
1387 hash_set<tree> *m_nontrapping;
1389 /* The hash table for remembering what we've seen. */
1390 hash_table<ssa_names_hasher> m_seen_ssa_names;
1393 /* Called by walk_dominator_tree, when entering the block BB. */
1395 nontrapping_dom_walker::before_dom_children (basic_block bb)
1399 gimple_stmt_iterator gsi;
1401 /* If we haven't seen all our predecessors, clear the hash-table. */
1402 FOR_EACH_EDGE (e, ei, bb->preds)
1403 if ((((size_t)e->src->aux) & 2) == 0)
1409 /* Mark this BB as being on the path to dominator root and as visited. */
1410 bb->aux = (void*)(1 | 2);
1412 /* And walk the statements in order. */
1413 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
1415 gimple stmt = gsi_stmt (gsi);
1417 if (is_gimple_call (stmt) && !nonfreeing_call_p (stmt))
1419 else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt))
1421 add_or_mark_expr (bb, gimple_assign_lhs (stmt), true);
1422 add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), false);
1427 /* Called by walk_dominator_tree, when basic block BB is exited. */
1429 nontrapping_dom_walker::after_dom_children (basic_block bb)
1431 /* This BB isn't on the path to dominator root anymore. */
1435 /* We see the expression EXP in basic block BB. If it's an interesting
1436 expression (an MEM_REF through an SSA_NAME) possibly insert the
1437 expression into the set NONTRAP or the hash table of seen expressions.
1438 STORE is true if this expression is on the LHS, otherwise it's on
1441 nontrapping_dom_walker::add_or_mark_expr (basic_block bb, tree exp, bool store)
1445 if (TREE_CODE (exp) == MEM_REF
1446 && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME
1447 && tree_fits_shwi_p (TREE_OPERAND (exp, 1))
1448 && (size = int_size_in_bytes (TREE_TYPE (exp))) > 0)
1450 tree name = TREE_OPERAND (exp, 0);
1451 struct name_to_bb map;
1453 struct name_to_bb *n2bb;
1454 basic_block found_bb = 0;
1456 /* Try to find the last seen MEM_REF through the same
1457 SSA_NAME, which can trap. */
1458 map.ssa_name_ver = SSA_NAME_VERSION (name);
1462 map.offset = tree_to_shwi (TREE_OPERAND (exp, 1));
1465 slot = m_seen_ssa_names.find_slot (&map, INSERT);
1467 if (n2bb && n2bb->phase >= nt_call_phase)
1468 found_bb = n2bb->bb;
1470 /* If we've found a trapping MEM_REF, _and_ it dominates EXP
1471 (it's in a basic block on the path from us to the dominator root)
1472 then we can't trap. */
1473 if (found_bb && (((size_t)found_bb->aux) & 1) == 1)
1475 m_nontrapping->add (exp);
1479 /* EXP might trap, so insert it into the hash table. */
1482 n2bb->phase = nt_call_phase;
1487 n2bb = XNEW (struct name_to_bb);
1488 n2bb->ssa_name_ver = SSA_NAME_VERSION (name);
1489 n2bb->phase = nt_call_phase;
1491 n2bb->store = store;
1492 n2bb->offset = map.offset;
1500 /* This is the entry point of gathering non trapping memory accesses.
1501 It will do a dominator walk over the whole function, and it will
1502 make use of the bb->aux pointers. It returns a set of trees
1503 (the MEM_REFs itself) which can't trap. */
1504 static hash_set<tree> *
1505 get_non_trapping (void)
1508 hash_set<tree> *nontrap = new hash_set<tree>;
1509 /* We're going to do a dominator walk, so ensure that we have
1510 dominance information. */
1511 calculate_dominance_info (CDI_DOMINATORS);
1513 nontrapping_dom_walker (CDI_DOMINATORS, nontrap)
1514 .walk (cfun->cfg->x_entry_block_ptr);
1516 clear_aux_for_blocks ();
1520 /* Do the main work of conditional store replacement. We already know
1521 that the recognized pattern looks like so:
1524 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
1527 fallthrough (edge E0)
1531 We check that MIDDLE_BB contains only one store, that that store
1532 doesn't trap (not via NOTRAP, but via checking if an access to the same
1533 memory location dominates us) and that the store has a "simple" RHS. */
1536 cond_store_replacement (basic_block middle_bb, basic_block join_bb,
1537 edge e0, edge e1, hash_set<tree> *nontrap)
1539 gimple assign = last_and_only_stmt (middle_bb);
1540 tree lhs, rhs, name, name2;
1543 gimple_stmt_iterator gsi;
1544 source_location locus;
1546 /* Check if middle_bb contains of only one store. */
1548 || !gimple_assign_single_p (assign)
1549 || gimple_has_volatile_ops (assign))
1552 locus = gimple_location (assign);
1553 lhs = gimple_assign_lhs (assign);
1554 rhs = gimple_assign_rhs1 (assign);
1555 if (TREE_CODE (lhs) != MEM_REF
1556 || TREE_CODE (TREE_OPERAND (lhs, 0)) != SSA_NAME
1557 || !is_gimple_reg_type (TREE_TYPE (lhs)))
1560 /* Prove that we can move the store down. We could also check
1561 TREE_THIS_NOTRAP here, but in that case we also could move stores,
1562 whose value is not available readily, which we want to avoid. */
1563 if (!nontrap->contains (lhs))
1566 /* Now we've checked the constraints, so do the transformation:
1567 1) Remove the single store. */
1568 gsi = gsi_for_stmt (assign);
1569 unlink_stmt_vdef (assign);
1570 gsi_remove (&gsi, true);
1571 release_defs (assign);
1573 /* 2) Insert a load from the memory of the store to the temporary
1574 on the edge which did not contain the store. */
1575 lhs = unshare_expr (lhs);
1576 name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
1577 new_stmt = gimple_build_assign (name, lhs);
1578 gimple_set_location (new_stmt, locus);
1579 gsi_insert_on_edge (e1, new_stmt);
1581 /* 3) Create a PHI node at the join block, with one argument
1582 holding the old RHS, and the other holding the temporary
1583 where we stored the old memory contents. */
1584 name2 = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
1585 newphi = create_phi_node (name2, join_bb);
1586 add_phi_arg (newphi, rhs, e0, locus);
1587 add_phi_arg (newphi, name, e1, locus);
1589 lhs = unshare_expr (lhs);
1590 new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
1592 /* 4) Insert that PHI node. */
1593 gsi = gsi_after_labels (join_bb);
1594 if (gsi_end_p (gsi))
1596 gsi = gsi_last_bb (join_bb);
1597 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
1600 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1605 /* Do the main work of conditional store replacement. */
1608 cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb,
1609 basic_block join_bb, gimple then_assign,
1612 tree lhs_base, lhs, then_rhs, else_rhs, name;
1613 source_location then_locus, else_locus;
1614 gimple_stmt_iterator gsi;
1618 if (then_assign == NULL
1619 || !gimple_assign_single_p (then_assign)
1620 || gimple_clobber_p (then_assign)
1621 || gimple_has_volatile_ops (then_assign)
1622 || else_assign == NULL
1623 || !gimple_assign_single_p (else_assign)
1624 || gimple_clobber_p (else_assign)
1625 || gimple_has_volatile_ops (else_assign))
1628 lhs = gimple_assign_lhs (then_assign);
1629 if (!is_gimple_reg_type (TREE_TYPE (lhs))
1630 || !operand_equal_p (lhs, gimple_assign_lhs (else_assign), 0))
1633 lhs_base = get_base_address (lhs);
1634 if (lhs_base == NULL_TREE
1635 || (!DECL_P (lhs_base) && TREE_CODE (lhs_base) != MEM_REF))
1638 then_rhs = gimple_assign_rhs1 (then_assign);
1639 else_rhs = gimple_assign_rhs1 (else_assign);
1640 then_locus = gimple_location (then_assign);
1641 else_locus = gimple_location (else_assign);
1643 /* Now we've checked the constraints, so do the transformation:
1644 1) Remove the stores. */
1645 gsi = gsi_for_stmt (then_assign);
1646 unlink_stmt_vdef (then_assign);
1647 gsi_remove (&gsi, true);
1648 release_defs (then_assign);
1650 gsi = gsi_for_stmt (else_assign);
1651 unlink_stmt_vdef (else_assign);
1652 gsi_remove (&gsi, true);
1653 release_defs (else_assign);
1655 /* 2) Create a PHI node at the join block, with one argument
1656 holding the old RHS, and the other holding the temporary
1657 where we stored the old memory contents. */
1658 name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
1659 newphi = create_phi_node (name, join_bb);
1660 add_phi_arg (newphi, then_rhs, EDGE_SUCC (then_bb, 0), then_locus);
1661 add_phi_arg (newphi, else_rhs, EDGE_SUCC (else_bb, 0), else_locus);
1663 new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
1665 /* 3) Insert that PHI node. */
1666 gsi = gsi_after_labels (join_bb);
1667 if (gsi_end_p (gsi))
1669 gsi = gsi_last_bb (join_bb);
1670 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
1673 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
1678 /* Conditional store replacement. We already know
1679 that the recognized pattern looks like so:
1682 if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
1692 fallthrough (edge E0)
1696 We check that it is safe to sink the store to JOIN_BB by verifying that
1697 there are no read-after-write or write-after-write dependencies in
1698 THEN_BB and ELSE_BB. */
1701 cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb,
1702 basic_block join_bb)
1704 gimple then_assign = last_and_only_stmt (then_bb);
1705 gimple else_assign = last_and_only_stmt (else_bb);
1706 vec<data_reference_p> then_datarefs, else_datarefs;
1707 vec<ddr_p> then_ddrs, else_ddrs;
1708 gimple then_store, else_store;
1709 bool found, ok = false, res;
1710 struct data_dependence_relation *ddr;
1711 data_reference_p then_dr, else_dr;
1713 tree then_lhs, else_lhs;
1714 basic_block blocks[3];
1716 if (MAX_STORES_TO_SINK == 0)
1719 /* Handle the case with single statement in THEN_BB and ELSE_BB. */
1720 if (then_assign && else_assign)
1721 return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
1722 then_assign, else_assign);
1724 /* Find data references. */
1725 then_datarefs.create (1);
1726 else_datarefs.create (1);
1727 if ((find_data_references_in_bb (NULL, then_bb, &then_datarefs)
1729 || !then_datarefs.length ()
1730 || (find_data_references_in_bb (NULL, else_bb, &else_datarefs)
1732 || !else_datarefs.length ())
1734 free_data_refs (then_datarefs);
1735 free_data_refs (else_datarefs);
1739 /* Find pairs of stores with equal LHS. */
1740 auto_vec<gimple, 1> then_stores, else_stores;
1741 FOR_EACH_VEC_ELT (then_datarefs, i, then_dr)
1743 if (DR_IS_READ (then_dr))
1746 then_store = DR_STMT (then_dr);
1747 then_lhs = gimple_get_lhs (then_store);
1748 if (then_lhs == NULL_TREE)
1752 FOR_EACH_VEC_ELT (else_datarefs, j, else_dr)
1754 if (DR_IS_READ (else_dr))
1757 else_store = DR_STMT (else_dr);
1758 else_lhs = gimple_get_lhs (else_store);
1759 if (else_lhs == NULL_TREE)
1762 if (operand_equal_p (then_lhs, else_lhs, 0))
1772 then_stores.safe_push (then_store);
1773 else_stores.safe_push (else_store);
1776 /* No pairs of stores found. */
1777 if (!then_stores.length ()
1778 || then_stores.length () > (unsigned) MAX_STORES_TO_SINK)
1780 free_data_refs (then_datarefs);
1781 free_data_refs (else_datarefs);
1785 /* Compute and check data dependencies in both basic blocks. */
1786 then_ddrs.create (1);
1787 else_ddrs.create (1);
1788 if (!compute_all_dependences (then_datarefs, &then_ddrs,
1790 || !compute_all_dependences (else_datarefs, &else_ddrs,
1793 free_dependence_relations (then_ddrs);
1794 free_dependence_relations (else_ddrs);
1795 free_data_refs (then_datarefs);
1796 free_data_refs (else_datarefs);
1799 blocks[0] = then_bb;
1800 blocks[1] = else_bb;
1801 blocks[2] = join_bb;
1802 renumber_gimple_stmt_uids_in_blocks (blocks, 3);
1804 /* Check that there are no read-after-write or write-after-write dependencies
1806 FOR_EACH_VEC_ELT (then_ddrs, i, ddr)
1808 struct data_reference *dra = DDR_A (ddr);
1809 struct data_reference *drb = DDR_B (ddr);
1811 if (DDR_ARE_DEPENDENT (ddr) != chrec_known
1812 && ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
1813 && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
1814 || (DR_IS_READ (drb) && DR_IS_WRITE (dra)
1815 && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
1816 || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
1818 free_dependence_relations (then_ddrs);
1819 free_dependence_relations (else_ddrs);
1820 free_data_refs (then_datarefs);
1821 free_data_refs (else_datarefs);
1826 /* Check that there are no read-after-write or write-after-write dependencies
1828 FOR_EACH_VEC_ELT (else_ddrs, i, ddr)
1830 struct data_reference *dra = DDR_A (ddr);
1831 struct data_reference *drb = DDR_B (ddr);
1833 if (DDR_ARE_DEPENDENT (ddr) != chrec_known
1834 && ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
1835 && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
1836 || (DR_IS_READ (drb) && DR_IS_WRITE (dra)
1837 && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
1838 || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
1840 free_dependence_relations (then_ddrs);
1841 free_dependence_relations (else_ddrs);
1842 free_data_refs (then_datarefs);
1843 free_data_refs (else_datarefs);
1848 /* Sink stores with same LHS. */
1849 FOR_EACH_VEC_ELT (then_stores, i, then_store)
1851 else_store = else_stores[i];
1852 res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
1853 then_store, else_store);
1857 free_dependence_relations (then_ddrs);
1858 free_dependence_relations (else_ddrs);
1859 free_data_refs (then_datarefs);
1860 free_data_refs (else_datarefs);
1865 /* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */
1868 local_mem_dependence (gimple stmt, basic_block bb)
1870 tree vuse = gimple_vuse (stmt);
1876 def = SSA_NAME_DEF_STMT (vuse);
1877 return (def && gimple_bb (def) == bb);
1880 /* Given a "diamond" control-flow pattern where BB0 tests a condition,
1881 BB1 and BB2 are "then" and "else" blocks dependent on this test,
1882 and BB3 rejoins control flow following BB1 and BB2, look for
1883 opportunities to hoist loads as follows. If BB3 contains a PHI of
1884 two loads, one each occurring in BB1 and BB2, and the loads are
1885 provably of adjacent fields in the same structure, then move both
1886 loads into BB0. Of course this can only be done if there are no
1887 dependencies preventing such motion.
1889 One of the hoisted loads will always be speculative, so the
1890 transformation is currently conservative:
1892 - The fields must be strictly adjacent.
1893 - The two fields must occupy a single memory block that is
1894 guaranteed to not cross a page boundary.
1896 The last is difficult to prove, as such memory blocks should be
1897 aligned on the minimum of the stack alignment boundary and the
1898 alignment guaranteed by heap allocation interfaces. Thus we rely
1899 on a parameter for the alignment value.
1901 Provided a good value is used for the last case, the first
1902 restriction could possibly be relaxed. */
1905 hoist_adjacent_loads (basic_block bb0, basic_block bb1,
1906 basic_block bb2, basic_block bb3)
1908 int param_align = PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE);
1909 unsigned param_align_bits = (unsigned) (param_align * BITS_PER_UNIT);
1912 /* Walk the phis in bb3 looking for an opportunity. We are looking
1913 for phis of two SSA names, one each of which is defined in bb1 and
1915 for (gsi = gsi_start_phis (bb3); !gsi_end_p (gsi); gsi_next (&gsi))
1917 gphi *phi_stmt = gsi.phi ();
1918 gimple def1, def2, defswap;
1919 tree arg1, arg2, ref1, ref2, field1, field2, fieldswap;
1920 tree tree_offset1, tree_offset2, tree_size2, next;
1921 int offset1, offset2, size2;
1923 gimple_stmt_iterator gsi2;
1924 basic_block bb_for_def1, bb_for_def2;
1926 if (gimple_phi_num_args (phi_stmt) != 2
1927 || virtual_operand_p (gimple_phi_result (phi_stmt)))
1930 arg1 = gimple_phi_arg_def (phi_stmt, 0);
1931 arg2 = gimple_phi_arg_def (phi_stmt, 1);
1933 if (TREE_CODE (arg1) != SSA_NAME
1934 || TREE_CODE (arg2) != SSA_NAME
1935 || SSA_NAME_IS_DEFAULT_DEF (arg1)
1936 || SSA_NAME_IS_DEFAULT_DEF (arg2))
1939 def1 = SSA_NAME_DEF_STMT (arg1);
1940 def2 = SSA_NAME_DEF_STMT (arg2);
1942 if ((gimple_bb (def1) != bb1 || gimple_bb (def2) != bb2)
1943 && (gimple_bb (def2) != bb1 || gimple_bb (def1) != bb2))
1946 /* Check the mode of the arguments to be sure a conditional move
1947 can be generated for it. */
1948 if (optab_handler (movcc_optab, TYPE_MODE (TREE_TYPE (arg1)))
1949 == CODE_FOR_nothing)
1952 /* Both statements must be assignments whose RHS is a COMPONENT_REF. */
1953 if (!gimple_assign_single_p (def1)
1954 || !gimple_assign_single_p (def2)
1955 || gimple_has_volatile_ops (def1)
1956 || gimple_has_volatile_ops (def2))
1959 ref1 = gimple_assign_rhs1 (def1);
1960 ref2 = gimple_assign_rhs1 (def2);
1962 if (TREE_CODE (ref1) != COMPONENT_REF
1963 || TREE_CODE (ref2) != COMPONENT_REF)
1966 /* The zeroth operand of the two component references must be
1967 identical. It is not sufficient to compare get_base_address of
1968 the two references, because this could allow for different
1969 elements of the same array in the two trees. It is not safe to
1970 assume that the existence of one array element implies the
1971 existence of a different one. */
1972 if (!operand_equal_p (TREE_OPERAND (ref1, 0), TREE_OPERAND (ref2, 0), 0))
1975 field1 = TREE_OPERAND (ref1, 1);
1976 field2 = TREE_OPERAND (ref2, 1);
1978 /* Check for field adjacency, and ensure field1 comes first. */
1979 for (next = DECL_CHAIN (field1);
1980 next && TREE_CODE (next) != FIELD_DECL;
1981 next = DECL_CHAIN (next))
1986 for (next = DECL_CHAIN (field2);
1987 next && TREE_CODE (next) != FIELD_DECL;
1988 next = DECL_CHAIN (next))
2002 bb_for_def1 = gimple_bb (def1);
2003 bb_for_def2 = gimple_bb (def2);
2005 /* Check for proper alignment of the first field. */
2006 tree_offset1 = bit_position (field1);
2007 tree_offset2 = bit_position (field2);
2008 tree_size2 = DECL_SIZE (field2);
2010 if (!tree_fits_uhwi_p (tree_offset1)
2011 || !tree_fits_uhwi_p (tree_offset2)
2012 || !tree_fits_uhwi_p (tree_size2))
2015 offset1 = tree_to_uhwi (tree_offset1);
2016 offset2 = tree_to_uhwi (tree_offset2);
2017 size2 = tree_to_uhwi (tree_size2);
2018 align1 = DECL_ALIGN (field1) % param_align_bits;
2020 if (offset1 % BITS_PER_UNIT != 0)
2023 /* For profitability, the two field references should fit within
2024 a single cache line. */
2025 if (align1 + offset2 - offset1 + size2 > param_align_bits)
2028 /* The two expressions cannot be dependent upon vdefs defined
2030 if (local_mem_dependence (def1, bb_for_def1)
2031 || local_mem_dependence (def2, bb_for_def2))
2034 /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
2035 bb0. We hoist the first one first so that a cache miss is handled
2036 efficiently regardless of hardware cache-fill policy. */
2037 gsi2 = gsi_for_stmt (def1);
2038 gsi_move_to_bb_end (&gsi2, bb0);
2039 gsi2 = gsi_for_stmt (def2);
2040 gsi_move_to_bb_end (&gsi2, bb0);
2042 if (dump_file && (dump_flags & TDF_DETAILS))
2045 "\nHoisting adjacent loads from %d and %d into %d: \n",
2046 bb_for_def1->index, bb_for_def2->index, bb0->index);
2047 print_gimple_stmt (dump_file, def1, 0, TDF_VOPS|TDF_MEMSYMS);
2048 print_gimple_stmt (dump_file, def2, 0, TDF_VOPS|TDF_MEMSYMS);
2053 /* Determine whether we should attempt to hoist adjacent loads out of
2054 diamond patterns in pass_phiopt. Always hoist loads if
2055 -fhoist-adjacent-loads is specified and the target machine has
2056 both a conditional move instruction and a defined cache line size. */
2059 gate_hoist_loads (void)
2061 return (flag_hoist_adjacent_loads == 1
2062 && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE)
2063 && HAVE_conditional_move);
2066 /* This pass tries to replaces an if-then-else block with an
2067 assignment. We have four kinds of transformations. Some of these
2068 transformations are also performed by the ifcvt RTL optimizer.
2070 Conditional Replacement
2071 -----------------------
2073 This transformation, implemented in conditional_replacement,
2077 if (cond) goto bb2; else goto bb1;
2080 x = PHI <0 (bb1), 1 (bb0), ...>;
2088 x = PHI <x' (bb0), ...>;
2090 We remove bb1 as it becomes unreachable. This occurs often due to
2091 gimplification of conditionals.
2096 This transformation, implemented in value_replacement, replaces
2099 if (a != b) goto bb2; else goto bb1;
2102 x = PHI <a (bb1), b (bb0), ...>;
2108 x = PHI <b (bb0), ...>;
2110 This opportunity can sometimes occur as a result of other
2114 Another case caught by value replacement looks like this:
2120 if (t3 != 0) goto bb1; else goto bb2;
2136 This transformation, implemented in abs_replacement, replaces
2139 if (a >= 0) goto bb2; else goto bb1;
2143 x = PHI <x (bb1), a (bb0), ...>;
2150 x = PHI <x' (bb0), ...>;
2155 This transformation, minmax_replacement replaces
2158 if (a <= b) goto bb2; else goto bb1;
2161 x = PHI <b (bb1), a (bb0), ...>;
2166 x' = MIN_EXPR (a, b)
2168 x = PHI <x' (bb0), ...>;
2170 A similar transformation is done for MAX_EXPR.
2173 This pass also performs a fifth transformation of a slightly different
2176 Adjacent Load Hoisting
2177 ----------------------
2179 This transformation replaces
2182 if (...) goto bb2; else goto bb1;
2184 x1 = (<expr>).field1;
2187 x2 = (<expr>).field2;
2194 x1 = (<expr>).field1;
2195 x2 = (<expr>).field2;
2196 if (...) goto bb2; else goto bb1;
2203 The purpose of this transformation is to enable generation of conditional
2204 move instructions such as Intel CMOVE or PowerPC ISEL. Because one of
2205 the loads is speculative, the transformation is restricted to very
2206 specific cases to avoid introducing a page fault. We are looking for
2214 where left and right are typically adjacent pointers in a tree structure. */
2218 const pass_data pass_data_phiopt =
2220 GIMPLE_PASS, /* type */
2221 "phiopt", /* name */
2222 OPTGROUP_NONE, /* optinfo_flags */
2223 TV_TREE_PHIOPT, /* tv_id */
2224 ( PROP_cfg | PROP_ssa ), /* properties_required */
2225 0, /* properties_provided */
2226 0, /* properties_destroyed */
2227 0, /* todo_flags_start */
2228 0, /* todo_flags_finish */
2231 class pass_phiopt : public gimple_opt_pass
2234 pass_phiopt (gcc::context *ctxt)
2235 : gimple_opt_pass (pass_data_phiopt, ctxt)
2238 /* opt_pass methods: */
2239 opt_pass * clone () { return new pass_phiopt (m_ctxt); }
2240 virtual bool gate (function *) { return flag_ssa_phiopt; }
2241 virtual unsigned int execute (function *)
2243 return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
2246 }; // class pass_phiopt
2251 make_pass_phiopt (gcc::context *ctxt)
2253 return new pass_phiopt (ctxt);
2258 const pass_data pass_data_cselim =
2260 GIMPLE_PASS, /* type */
2261 "cselim", /* name */
2262 OPTGROUP_NONE, /* optinfo_flags */
2263 TV_TREE_PHIOPT, /* tv_id */
2264 ( PROP_cfg | PROP_ssa ), /* properties_required */
2265 0, /* properties_provided */
2266 0, /* properties_destroyed */
2267 0, /* todo_flags_start */
2268 0, /* todo_flags_finish */
2271 class pass_cselim : public gimple_opt_pass
2274 pass_cselim (gcc::context *ctxt)
2275 : gimple_opt_pass (pass_data_cselim, ctxt)
2278 /* opt_pass methods: */
2279 virtual bool gate (function *) { return flag_tree_cselim; }
2280 virtual unsigned int execute (function *) { return tree_ssa_cs_elim (); }
2282 }; // class pass_cselim
2287 make_pass_cselim (gcc::context *ctxt)
2289 return new pass_cselim (ctxt);