| /* Optimization of PHI nodes by converting them into straightline code. |
| Copyright (C) 2004-2021 Free Software Foundation, Inc. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify it |
| under the terms of the GNU General Public License as published by the |
| Free Software Foundation; either version 3, or (at your option) any |
| later version. |
| |
| GCC is distributed in the hope that it will be useful, but WITHOUT |
| ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING3. If not see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "backend.h" |
| #include "insn-codes.h" |
| #include "rtl.h" |
| #include "tree.h" |
| #include "gimple.h" |
| #include "cfghooks.h" |
| #include "tree-pass.h" |
| #include "ssa.h" |
| #include "optabs-tree.h" |
| #include "insn-config.h" |
| #include "gimple-pretty-print.h" |
| #include "fold-const.h" |
| #include "stor-layout.h" |
| #include "cfganal.h" |
| #include "gimplify.h" |
| #include "gimple-iterator.h" |
| #include "gimplify-me.h" |
| #include "tree-cfg.h" |
| #include "tree-dfa.h" |
| #include "domwalk.h" |
| #include "cfgloop.h" |
| #include "tree-data-ref.h" |
| #include "tree-scalar-evolution.h" |
| #include "tree-inline.h" |
| #include "case-cfn-macros.h" |
| #include "tree-eh.h" |
| #include "gimple-fold.h" |
| #include "internal-fn.h" |
| |
| static unsigned int tree_ssa_phiopt_worker (bool, bool, bool); |
| static bool two_value_replacement (basic_block, basic_block, edge, gphi *, |
| tree, tree); |
| static bool conditional_replacement (basic_block, basic_block, |
| edge, edge, gphi *, tree, tree); |
| static gphi *factor_out_conditional_conversion (edge, edge, gphi *, tree, tree, |
| gimple *); |
| static int value_replacement (basic_block, basic_block, |
| edge, edge, gimple *, tree, tree); |
| static bool minmax_replacement (basic_block, basic_block, |
| edge, edge, gimple *, tree, tree); |
| static bool abs_replacement (basic_block, basic_block, |
| edge, edge, gimple *, tree, tree); |
| static bool xor_replacement (basic_block, basic_block, |
| edge, edge, gimple *, tree, tree); |
| static bool cond_removal_in_popcount_clz_ctz_pattern (basic_block, basic_block, |
| edge, edge, gimple *, |
| tree, tree); |
| static bool cond_store_replacement (basic_block, basic_block, edge, edge, |
| hash_set<tree> *); |
| static bool cond_if_else_store_replacement (basic_block, basic_block, basic_block); |
| static hash_set<tree> * get_non_trapping (); |
| static void replace_phi_edge_with_variable (basic_block, edge, gimple *, tree); |
| static void hoist_adjacent_loads (basic_block, basic_block, |
| basic_block, basic_block); |
| static bool gate_hoist_loads (void); |
| |
| /* This pass tries to transform conditional stores into unconditional |
| ones, enabling further simplifications with the simpler then and else |
| blocks. In particular it replaces this: |
| |
| bb0: |
| if (cond) goto bb2; else goto bb1; |
| bb1: |
| *p = RHS; |
| bb2: |
| |
| with |
| |
| bb0: |
| if (cond) goto bb1; else goto bb2; |
| bb1: |
| condtmp' = *p; |
| bb2: |
| condtmp = PHI <RHS, condtmp'> |
| *p = condtmp; |
| |
| This transformation can only be done under several constraints, |
| documented below. It also replaces: |
| |
| bb0: |
| if (cond) goto bb2; else goto bb1; |
| bb1: |
| *p = RHS1; |
| goto bb3; |
| bb2: |
| *p = RHS2; |
| bb3: |
| |
| with |
| |
| bb0: |
| if (cond) goto bb3; else goto bb1; |
| bb1: |
| bb3: |
| condtmp = PHI <RHS1, RHS2> |
| *p = condtmp; */ |
| |
| static unsigned int |
| tree_ssa_cs_elim (void) |
| { |
| unsigned todo; |
| /* ??? We are not interested in loop related info, but the following |
| will create it, ICEing as we didn't init loops with pre-headers. |
| An interfacing issue of find_data_references_in_bb. */ |
| loop_optimizer_init (LOOPS_NORMAL); |
| scev_initialize (); |
| todo = tree_ssa_phiopt_worker (true, false, false); |
| scev_finalize (); |
| loop_optimizer_finalize (); |
| return todo; |
| } |
| |
| /* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */ |
| |
| static gphi * |
| single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1) |
| { |
| gimple_stmt_iterator i; |
| gphi *phi = NULL; |
| if (gimple_seq_singleton_p (seq)) |
| return as_a <gphi *> (gsi_stmt (gsi_start (seq))); |
| for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i)) |
| { |
| gphi *p = as_a <gphi *> (gsi_stmt (i)); |
| /* If the PHI arguments are equal then we can skip this PHI. */ |
| if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p, e0->dest_idx), |
| gimple_phi_arg_def (p, e1->dest_idx))) |
| continue; |
| |
| /* If we already have a PHI that has the two edge arguments are |
| different, then return it is not a singleton for these PHIs. */ |
| if (phi) |
| return NULL; |
| |
| phi = p; |
| } |
| return phi; |
| } |
| |
| /* The core routine of conditional store replacement and normal |
| phi optimizations. Both share much of the infrastructure in how |
| to match applicable basic block patterns. DO_STORE_ELIM is true |
| when we want to do conditional store replacement, false otherwise. |
| DO_HOIST_LOADS is true when we want to hoist adjacent loads out |
| of diamond control flow patterns, false otherwise. */ |
| static unsigned int |
| tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p) |
| { |
| basic_block bb; |
| basic_block *bb_order; |
| unsigned n, i; |
| bool cfgchanged = false; |
| hash_set<tree> *nontrap = 0; |
| |
| calculate_dominance_info (CDI_DOMINATORS); |
| |
| if (do_store_elim) |
| /* Calculate the set of non-trapping memory accesses. */ |
| nontrap = get_non_trapping (); |
| |
| /* Search every basic block for COND_EXPR we may be able to optimize. |
| |
| We walk the blocks in order that guarantees that a block with |
| a single predecessor is processed before the predecessor. |
| This ensures that we collapse inner ifs before visiting the |
| outer ones, and also that we do not try to visit a removed |
| block. */ |
| bb_order = single_pred_before_succ_order (); |
| n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS; |
| |
| for (i = 0; i < n; i++) |
| { |
| gimple *cond_stmt; |
| gphi *phi; |
| basic_block bb1, bb2; |
| edge e1, e2; |
| tree arg0, arg1; |
| |
| bb = bb_order[i]; |
| |
| cond_stmt = last_stmt (bb); |
| /* Check to see if the last statement is a GIMPLE_COND. */ |
| if (!cond_stmt |
| || gimple_code (cond_stmt) != GIMPLE_COND) |
| continue; |
| |
| e1 = EDGE_SUCC (bb, 0); |
| bb1 = e1->dest; |
| e2 = EDGE_SUCC (bb, 1); |
| bb2 = e2->dest; |
| |
| /* We cannot do the optimization on abnormal edges. */ |
| if ((e1->flags & EDGE_ABNORMAL) != 0 |
| || (e2->flags & EDGE_ABNORMAL) != 0) |
| continue; |
| |
| /* If either bb1's succ or bb2 or bb2's succ is non NULL. */ |
| if (EDGE_COUNT (bb1->succs) == 0 |
| || bb2 == NULL |
| || EDGE_COUNT (bb2->succs) == 0) |
| continue; |
| |
| /* Find the bb which is the fall through to the other. */ |
| if (EDGE_SUCC (bb1, 0)->dest == bb2) |
| ; |
| else if (EDGE_SUCC (bb2, 0)->dest == bb1) |
| { |
| std::swap (bb1, bb2); |
| std::swap (e1, e2); |
| } |
| else if (do_store_elim |
| && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest) |
| { |
| basic_block bb3 = EDGE_SUCC (bb1, 0)->dest; |
| |
| if (!single_succ_p (bb1) |
| || (EDGE_SUCC (bb1, 0)->flags & EDGE_FALLTHRU) == 0 |
| || !single_succ_p (bb2) |
| || (EDGE_SUCC (bb2, 0)->flags & EDGE_FALLTHRU) == 0 |
| || EDGE_COUNT (bb3->preds) != 2) |
| continue; |
| if (cond_if_else_store_replacement (bb1, bb2, bb3)) |
| cfgchanged = true; |
| continue; |
| } |
| else if (do_hoist_loads |
| && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest) |
| { |
| basic_block bb3 = EDGE_SUCC (bb1, 0)->dest; |
| |
| if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt))) |
| && single_succ_p (bb1) |
| && single_succ_p (bb2) |
| && single_pred_p (bb1) |
| && single_pred_p (bb2) |
| && EDGE_COUNT (bb->succs) == 2 |
| && EDGE_COUNT (bb3->preds) == 2 |
| /* If one edge or the other is dominant, a conditional move |
| is likely to perform worse than the well-predicted branch. */ |
| && !predictable_edge_p (EDGE_SUCC (bb, 0)) |
| && !predictable_edge_p (EDGE_SUCC (bb, 1))) |
| hoist_adjacent_loads (bb, bb1, bb2, bb3); |
| continue; |
| } |
| else |
| continue; |
| |
| e1 = EDGE_SUCC (bb1, 0); |
| |
| /* Make sure that bb1 is just a fall through. */ |
| if (!single_succ_p (bb1) |
| || (e1->flags & EDGE_FALLTHRU) == 0) |
| continue; |
| |
| /* Also make sure that bb1 only have one predecessor and that it |
| is bb. */ |
| if (!single_pred_p (bb1) |
| || single_pred (bb1) != bb) |
| continue; |
| |
| if (do_store_elim) |
| { |
| /* bb1 is the middle block, bb2 the join block, bb the split block, |
| e1 the fallthrough edge from bb1 to bb2. We can't do the |
| optimization if the join block has more than two predecessors. */ |
| if (EDGE_COUNT (bb2->preds) > 2) |
| continue; |
| if (cond_store_replacement (bb1, bb2, e1, e2, nontrap)) |
| cfgchanged = true; |
| } |
| else |
| { |
| gimple_seq phis = phi_nodes (bb2); |
| gimple_stmt_iterator gsi; |
| bool candorest = true; |
| |
| /* Value replacement can work with more than one PHI |
| so try that first. */ |
| if (!early_p) |
| for (gsi = gsi_start (phis); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| phi = as_a <gphi *> (gsi_stmt (gsi)); |
| arg0 = gimple_phi_arg_def (phi, e1->dest_idx); |
| arg1 = gimple_phi_arg_def (phi, e2->dest_idx); |
| if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1) == 2) |
| { |
| candorest = false; |
| cfgchanged = true; |
| break; |
| } |
| } |
| |
| if (!candorest) |
| continue; |
| |
| phi = single_non_singleton_phi_for_edges (phis, e1, e2); |
| if (!phi) |
| continue; |
| |
| arg0 = gimple_phi_arg_def (phi, e1->dest_idx); |
| arg1 = gimple_phi_arg_def (phi, e2->dest_idx); |
| |
| /* Something is wrong if we cannot find the arguments in the PHI |
| node. */ |
| gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE); |
| |
| gphi *newphi = factor_out_conditional_conversion (e1, e2, phi, |
| arg0, arg1, |
| cond_stmt); |
| if (newphi != NULL) |
| { |
| phi = newphi; |
| /* factor_out_conditional_conversion may create a new PHI in |
| BB2 and eliminate an existing PHI in BB2. Recompute values |
| that may be affected by that change. */ |
| arg0 = gimple_phi_arg_def (phi, e1->dest_idx); |
| arg1 = gimple_phi_arg_def (phi, e2->dest_idx); |
| gcc_assert (arg0 != NULL_TREE && arg1 != NULL_TREE); |
| } |
| |
| /* Do the replacement of conditional if it can be done. */ |
| if (!early_p && two_value_replacement (bb, bb1, e2, phi, arg0, arg1)) |
| cfgchanged = true; |
| else if (!early_p |
| && conditional_replacement (bb, bb1, e1, e2, phi, |
| arg0, arg1)) |
| cfgchanged = true; |
| else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
| cfgchanged = true; |
| else if (!early_p |
| && xor_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
| cfgchanged = true; |
| else if (!early_p |
| && cond_removal_in_popcount_clz_ctz_pattern (bb, bb1, e1, |
| e2, phi, arg0, |
| arg1)) |
| cfgchanged = true; |
| else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
| cfgchanged = true; |
| } |
| } |
| |
| free (bb_order); |
| |
| if (do_store_elim) |
| delete nontrap; |
| /* If the CFG has changed, we should cleanup the CFG. */ |
| if (cfgchanged && do_store_elim) |
| { |
| /* In cond-store replacement we have added some loads on edges |
| and new VOPS (as we moved the store, and created a load). */ |
| gsi_commit_edge_inserts (); |
| return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals; |
| } |
| else if (cfgchanged) |
| return TODO_cleanup_cfg; |
| return 0; |
| } |
| |
| /* Replace PHI node element whose edge is E in block BB with variable NEW. |
| Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK |
| is known to have two edges, one of which must reach BB). */ |
| |
| static void |
| replace_phi_edge_with_variable (basic_block cond_block, |
| edge e, gimple *phi, tree new_tree) |
| { |
| basic_block bb = gimple_bb (phi); |
| basic_block block_to_remove; |
| gimple_stmt_iterator gsi; |
| |
| /* Change the PHI argument to new. */ |
| SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree); |
| |
| /* Remove the empty basic block. */ |
| if (EDGE_SUCC (cond_block, 0)->dest == bb) |
| { |
| EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU; |
| EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); |
| EDGE_SUCC (cond_block, 0)->probability = profile_probability::always (); |
| |
| block_to_remove = EDGE_SUCC (cond_block, 1)->dest; |
| } |
| else |
| { |
| EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU; |
| EDGE_SUCC (cond_block, 1)->flags |
| &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); |
| EDGE_SUCC (cond_block, 1)->probability = profile_probability::always (); |
| |
| block_to_remove = EDGE_SUCC (cond_block, 0)->dest; |
| } |
| delete_basic_block (block_to_remove); |
| |
| /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ |
| gsi = gsi_last_bb (cond_block); |
| gsi_remove (&gsi, true); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| fprintf (dump_file, |
| "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n", |
| cond_block->index, |
| bb->index); |
| } |
| |
| /* PR66726: Factor conversion out of COND_EXPR. If the arguments of the PHI |
| stmt are CONVERT_STMT, factor out the conversion and perform the conversion |
| to the result of PHI stmt. COND_STMT is the controlling predicate. |
| Return the newly-created PHI, if any. */ |
| |
| static gphi * |
| factor_out_conditional_conversion (edge e0, edge e1, gphi *phi, |
| tree arg0, tree arg1, gimple *cond_stmt) |
| { |
| gimple *arg0_def_stmt = NULL, *arg1_def_stmt = NULL, *new_stmt; |
| tree new_arg0 = NULL_TREE, new_arg1 = NULL_TREE; |
| tree temp, result; |
| gphi *newphi; |
| gimple_stmt_iterator gsi, gsi_for_def; |
| location_t locus = gimple_location (phi); |
| enum tree_code convert_code; |
| |
| /* Handle only PHI statements with two arguments. TODO: If all |
| other arguments to PHI are INTEGER_CST or if their defining |
| statement have the same unary operation, we can handle more |
| than two arguments too. */ |
| if (gimple_phi_num_args (phi) != 2) |
| return NULL; |
| |
| /* First canonicalize to simplify tests. */ |
| if (TREE_CODE (arg0) != SSA_NAME) |
| { |
| std::swap (arg0, arg1); |
| std::swap (e0, e1); |
| } |
| |
| if (TREE_CODE (arg0) != SSA_NAME |
| || (TREE_CODE (arg1) != SSA_NAME |
| && TREE_CODE (arg1) != INTEGER_CST)) |
| return NULL; |
| |
| /* Check if arg0 is an SSA_NAME and the stmt which defines arg0 is |
| a conversion. */ |
| arg0_def_stmt = SSA_NAME_DEF_STMT (arg0); |
| if (!gimple_assign_cast_p (arg0_def_stmt)) |
| return NULL; |
| |
| /* Use the RHS as new_arg0. */ |
| convert_code = gimple_assign_rhs_code (arg0_def_stmt); |
| new_arg0 = gimple_assign_rhs1 (arg0_def_stmt); |
| if (convert_code == VIEW_CONVERT_EXPR) |
| { |
| new_arg0 = TREE_OPERAND (new_arg0, 0); |
| if (!is_gimple_reg_type (TREE_TYPE (new_arg0))) |
| return NULL; |
| } |
| if (TREE_CODE (new_arg0) == SSA_NAME |
| && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_arg0)) |
| return NULL; |
| |
| if (TREE_CODE (arg1) == SSA_NAME) |
| { |
| /* Check if arg1 is an SSA_NAME and the stmt which defines arg1 |
| is a conversion. */ |
| arg1_def_stmt = SSA_NAME_DEF_STMT (arg1); |
| if (!is_gimple_assign (arg1_def_stmt) |
| || gimple_assign_rhs_code (arg1_def_stmt) != convert_code) |
| return NULL; |
| |
| /* Either arg1_def_stmt or arg0_def_stmt should be conditional. */ |
| if (dominated_by_p (CDI_DOMINATORS, gimple_bb (phi), gimple_bb (arg0_def_stmt)) |
| && dominated_by_p (CDI_DOMINATORS, |
| gimple_bb (phi), gimple_bb (arg1_def_stmt))) |
| return NULL; |
| |
| /* Use the RHS as new_arg1. */ |
| new_arg1 = gimple_assign_rhs1 (arg1_def_stmt); |
| if (convert_code == VIEW_CONVERT_EXPR) |
| new_arg1 = TREE_OPERAND (new_arg1, 0); |
| if (TREE_CODE (new_arg1) == SSA_NAME |
| && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_arg1)) |
| return NULL; |
| } |
| else |
| { |
| /* arg0_def_stmt should be conditional. */ |
| if (dominated_by_p (CDI_DOMINATORS, gimple_bb (phi), gimple_bb (arg0_def_stmt))) |
| return NULL; |
| /* If arg1 is an INTEGER_CST, fold it to new type. */ |
| if (INTEGRAL_TYPE_P (TREE_TYPE (new_arg0)) |
| && int_fits_type_p (arg1, TREE_TYPE (new_arg0))) |
| { |
| if (gimple_assign_cast_p (arg0_def_stmt)) |
| { |
| /* For the INTEGER_CST case, we are just moving the |
| conversion from one place to another, which can often |
| hurt as the conversion moves further away from the |
| statement that computes the value. So, perform this |
| only if new_arg0 is an operand of COND_STMT, or |
| if arg0_def_stmt is the only non-debug stmt in |
| its basic block, because then it is possible this |
| could enable further optimizations (minmax replacement |
| etc.). See PR71016. */ |
| if (new_arg0 != gimple_cond_lhs (cond_stmt) |
| && new_arg0 != gimple_cond_rhs (cond_stmt) |
| && gimple_bb (arg0_def_stmt) == e0->src) |
| { |
| gsi = gsi_for_stmt (arg0_def_stmt); |
| gsi_prev_nondebug (&gsi); |
| if (!gsi_end_p (gsi)) |
| { |
| if (gassign *assign |
| = dyn_cast <gassign *> (gsi_stmt (gsi))) |
| { |
| tree lhs = gimple_assign_lhs (assign); |
| enum tree_code ass_code |
| = gimple_assign_rhs_code (assign); |
| if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) |
| return NULL; |
| if (lhs != gimple_assign_rhs1 (arg0_def_stmt)) |
| return NULL; |
| gsi_prev_nondebug (&gsi); |
| if (!gsi_end_p (gsi)) |
| return NULL; |
| } |
| else |
| return NULL; |
| } |
| gsi = gsi_for_stmt (arg0_def_stmt); |
| gsi_next_nondebug (&gsi); |
| if (!gsi_end_p (gsi)) |
| return NULL; |
| } |
| new_arg1 = fold_convert (TREE_TYPE (new_arg0), arg1); |
| } |
| else |
| return NULL; |
| } |
| else |
| return NULL; |
| } |
| |
| /* If arg0/arg1 have > 1 use, then this transformation actually increases |
| the number of expressions evaluated at runtime. */ |
| if (!has_single_use (arg0) |
| || (arg1_def_stmt && !has_single_use (arg1))) |
| return NULL; |
| |
| /* If types of new_arg0 and new_arg1 are different bailout. */ |
| if (!types_compatible_p (TREE_TYPE (new_arg0), TREE_TYPE (new_arg1))) |
| return NULL; |
| |
| /* Create a new PHI stmt. */ |
| result = PHI_RESULT (phi); |
| temp = make_ssa_name (TREE_TYPE (new_arg0), NULL); |
| newphi = create_phi_node (temp, gimple_bb (phi)); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "PHI "); |
| print_generic_expr (dump_file, gimple_phi_result (phi)); |
| fprintf (dump_file, |
| " changed to factor conversion out from COND_EXPR.\n"); |
| fprintf (dump_file, "New stmt with CAST that defines "); |
| print_generic_expr (dump_file, result); |
| fprintf (dump_file, ".\n"); |
| } |
| |
| /* Remove the old cast(s) that has single use. */ |
| gsi_for_def = gsi_for_stmt (arg0_def_stmt); |
| gsi_remove (&gsi_for_def, true); |
| release_defs (arg0_def_stmt); |
| |
| if (arg1_def_stmt) |
| { |
| gsi_for_def = gsi_for_stmt (arg1_def_stmt); |
| gsi_remove (&gsi_for_def, true); |
| release_defs (arg1_def_stmt); |
| } |
| |
| add_phi_arg (newphi, new_arg0, e0, locus); |
| add_phi_arg (newphi, new_arg1, e1, locus); |
| |
| /* Create the conversion stmt and insert it. */ |
| if (convert_code == VIEW_CONVERT_EXPR) |
| { |
| temp = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (result), temp); |
| new_stmt = gimple_build_assign (result, temp); |
| } |
| else |
| new_stmt = gimple_build_assign (result, convert_code, temp); |
| gsi = gsi_after_labels (gimple_bb (phi)); |
| gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT); |
| |
| /* Remove the original PHI stmt. */ |
| gsi = gsi_for_stmt (phi); |
| gsi_remove (&gsi, true); |
| return newphi; |
| } |
| |
| /* Optimize |
| # x_5 in range [cst1, cst2] where cst2 = cst1 + 1 |
| if (x_5 op cstN) # where op is == or != and N is 1 or 2 |
| goto bb3; |
| else |
| goto bb4; |
| bb3: |
| bb4: |
| # r_6 = PHI<cst3(2), cst4(3)> # where cst3 == cst4 + 1 or cst4 == cst3 + 1 |
| |
| to r_6 = x_5 + (min (cst3, cst4) - cst1) or |
| r_6 = (min (cst3, cst4) + cst1) - x_5 depending on op, N and which |
| of cst3 and cst4 is smaller. */ |
| |
| static bool |
| two_value_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e1, gphi *phi, tree arg0, tree arg1) |
| { |
| /* Only look for adjacent integer constants. */ |
| if (!INTEGRAL_TYPE_P (TREE_TYPE (arg0)) |
| || !INTEGRAL_TYPE_P (TREE_TYPE (arg1)) |
| || TREE_CODE (arg0) != INTEGER_CST |
| || TREE_CODE (arg1) != INTEGER_CST |
| || (tree_int_cst_lt (arg0, arg1) |
| ? wi::to_widest (arg0) + 1 != wi::to_widest (arg1) |
| : wi::to_widest (arg1) + 1 != wi::to_widest (arg0))) |
| return false; |
| |
| if (!empty_block_p (middle_bb)) |
| return false; |
| |
| gimple *stmt = last_stmt (cond_bb); |
| tree lhs = gimple_cond_lhs (stmt); |
| tree rhs = gimple_cond_rhs (stmt); |
| |
| if (TREE_CODE (lhs) != SSA_NAME |
| || !INTEGRAL_TYPE_P (TREE_TYPE (lhs)) |
| || TREE_CODE (rhs) != INTEGER_CST) |
| return false; |
| |
| switch (gimple_cond_code (stmt)) |
| { |
| case EQ_EXPR: |
| case NE_EXPR: |
| break; |
| default: |
| return false; |
| } |
| |
| /* Defer boolean x ? 0 : {1,-1} or x ? {1,-1} : 0 to |
| conditional_replacement. */ |
| if (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE |
| && (integer_zerop (arg0) |
| || integer_zerop (arg1) |
| || TREE_CODE (TREE_TYPE (arg0)) == BOOLEAN_TYPE |
| || (TYPE_PRECISION (TREE_TYPE (arg0)) |
| <= TYPE_PRECISION (TREE_TYPE (lhs))))) |
| return false; |
| |
| wide_int min, max; |
| if (get_range_info (lhs, &min, &max) != VR_RANGE) |
| { |
| int prec = TYPE_PRECISION (TREE_TYPE (lhs)); |
| signop sgn = TYPE_SIGN (TREE_TYPE (lhs)); |
| min = wi::min_value (prec, sgn); |
| max = wi::max_value (prec, sgn); |
| } |
| if (min + 1 != max |
| || (wi::to_wide (rhs) != min |
| && wi::to_wide (rhs) != max)) |
| return false; |
| |
| /* We need to know which is the true edge and which is the false |
| edge so that we know when to invert the condition below. */ |
| edge true_edge, false_edge; |
| extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
| if ((gimple_cond_code (stmt) == EQ_EXPR) |
| ^ (wi::to_wide (rhs) == max) |
| ^ (e1 == false_edge)) |
| std::swap (arg0, arg1); |
| |
| tree type; |
| if (TYPE_PRECISION (TREE_TYPE (lhs)) == TYPE_PRECISION (TREE_TYPE (arg0))) |
| { |
| /* Avoid performing the arithmetics in bool type which has different |
| semantics, otherwise prefer unsigned types from the two with |
| the same precision. */ |
| if (TREE_CODE (TREE_TYPE (arg0)) == BOOLEAN_TYPE |
| || !TYPE_UNSIGNED (TREE_TYPE (arg0))) |
| type = TREE_TYPE (lhs); |
| else |
| type = TREE_TYPE (arg0); |
| } |
| else if (TYPE_PRECISION (TREE_TYPE (lhs)) > TYPE_PRECISION (TREE_TYPE (arg0))) |
| type = TREE_TYPE (lhs); |
| else |
| type = TREE_TYPE (arg0); |
| |
| min = wide_int::from (min, TYPE_PRECISION (type), |
| TYPE_SIGN (TREE_TYPE (lhs))); |
| wide_int a = wide_int::from (wi::to_wide (arg0), TYPE_PRECISION (type), |
| TYPE_SIGN (TREE_TYPE (arg0))); |
| enum tree_code code; |
| wi::overflow_type ovf; |
| if (tree_int_cst_lt (arg0, arg1)) |
| { |
| code = PLUS_EXPR; |
| a -= min; |
| if (!TYPE_UNSIGNED (type)) |
| { |
| /* lhs is known to be in range [min, min+1] and we want to add a |
| to it. Check if that operation can overflow for those 2 values |
| and if yes, force unsigned type. */ |
| wi::add (min + (wi::neg_p (a) ? 0 : 1), a, SIGNED, &ovf); |
| if (ovf) |
| type = unsigned_type_for (type); |
| } |
| } |
| else |
| { |
| code = MINUS_EXPR; |
| a += min; |
| if (!TYPE_UNSIGNED (type)) |
| { |
| /* lhs is known to be in range [min, min+1] and we want to subtract |
| it from a. Check if that operation can overflow for those 2 |
| values and if yes, force unsigned type. */ |
| wi::sub (a, min + (wi::neg_p (min) ? 0 : 1), SIGNED, &ovf); |
| if (ovf) |
| type = unsigned_type_for (type); |
| } |
| } |
| |
| tree arg = wide_int_to_tree (type, a); |
| gimple_stmt_iterator gsi = gsi_for_stmt (stmt); |
| if (!useless_type_conversion_p (type, TREE_TYPE (lhs))) |
| lhs = gimplify_build1 (&gsi, NOP_EXPR, type, lhs); |
| tree new_rhs; |
| if (code == PLUS_EXPR) |
| new_rhs = gimplify_build2 (&gsi, PLUS_EXPR, type, lhs, arg); |
| else |
| new_rhs = gimplify_build2 (&gsi, MINUS_EXPR, type, arg, lhs); |
| if (!useless_type_conversion_p (TREE_TYPE (arg0), type)) |
| new_rhs = gimplify_build1 (&gsi, NOP_EXPR, TREE_TYPE (arg0), new_rhs); |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, new_rhs); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| |
| /* The function conditional_replacement does the main work of doing the |
| conditional replacement. Return true if the replacement is done. |
| Otherwise return false. |
| BB is the basic block where the replacement is going to be done on. ARG0 |
| is argument 0 from PHI. Likewise for ARG1. */ |
| |
| static bool |
| conditional_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e0, edge e1, gphi *phi, |
| tree arg0, tree arg1) |
| { |
| tree result; |
| gimple *stmt; |
| gassign *new_stmt; |
| tree cond; |
| gimple_stmt_iterator gsi; |
| edge true_edge, false_edge; |
| tree new_var, new_var2; |
| bool neg = false; |
| int shift = 0; |
| tree nonzero_arg; |
| |
| /* FIXME: Gimplification of complex type is too hard for now. */ |
| /* We aren't prepared to handle vectors either (and it is a question |
| if it would be worthwhile anyway). */ |
| if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0)) |
| || POINTER_TYPE_P (TREE_TYPE (arg0))) |
| || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1)) |
| || POINTER_TYPE_P (TREE_TYPE (arg1)))) |
| return false; |
| |
| /* The PHI arguments have the constants 0 and 1, or 0 and -1 or |
| 0 and (1 << cst), then convert it to the conditional. */ |
| if (integer_zerop (arg0)) |
| nonzero_arg = arg1; |
| else if (integer_zerop (arg1)) |
| nonzero_arg = arg0; |
| else |
| return false; |
| if (integer_pow2p (nonzero_arg)) |
| { |
| shift = tree_log2 (nonzero_arg); |
| if (shift && POINTER_TYPE_P (TREE_TYPE (nonzero_arg))) |
| return false; |
| } |
| else if (integer_all_onesp (nonzero_arg)) |
| neg = true; |
| else |
| return false; |
| |
| if (!empty_block_p (middle_bb)) |
| return false; |
| |
| /* At this point we know we have a GIMPLE_COND with two successors. |
| One successor is BB, the other successor is an empty block which |
| falls through into BB. |
| |
| There is a single PHI node at the join point (BB) and its arguments |
| are constants (0, 1) or (0, -1) or (0, (1 << shift)). |
| |
| So, given the condition COND, and the two PHI arguments, we can |
| rewrite this PHI into non-branching code: |
| |
| dest = (COND) or dest = COND' or dest = (COND) << shift |
| |
| We use the condition as-is if the argument associated with the |
| true edge has the value one or the argument associated with the |
| false edge as the value zero. Note that those conditions are not |
| the same since only one of the outgoing edges from the GIMPLE_COND |
| will directly reach BB and thus be associated with an argument. */ |
| |
| stmt = last_stmt (cond_bb); |
| result = PHI_RESULT (phi); |
| |
| /* To handle special cases like floating point comparison, it is easier and |
| less error-prone to build a tree and gimplify it on the fly though it is |
| less efficient. */ |
| cond = fold_build2_loc (gimple_location (stmt), |
| gimple_cond_code (stmt), boolean_type_node, |
| gimple_cond_lhs (stmt), gimple_cond_rhs (stmt)); |
| |
| /* We need to know which is the true edge and which is the false |
| edge so that we know when to invert the condition below. */ |
| extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
| if ((e0 == true_edge && integer_zerop (arg0)) |
| || (e0 == false_edge && !integer_zerop (arg0)) |
| || (e1 == true_edge && integer_zerop (arg1)) |
| || (e1 == false_edge && !integer_zerop (arg1))) |
| cond = fold_build1_loc (gimple_location (stmt), |
| TRUTH_NOT_EXPR, TREE_TYPE (cond), cond); |
| |
| if (neg) |
| { |
| cond = fold_convert_loc (gimple_location (stmt), |
| TREE_TYPE (result), cond); |
| cond = fold_build1_loc (gimple_location (stmt), |
| NEGATE_EXPR, TREE_TYPE (cond), cond); |
| } |
| else if (shift) |
| { |
| cond = fold_convert_loc (gimple_location (stmt), |
| TREE_TYPE (result), cond); |
| cond = fold_build2_loc (gimple_location (stmt), |
| LSHIFT_EXPR, TREE_TYPE (cond), cond, |
| build_int_cst (integer_type_node, shift)); |
| } |
| |
| /* Insert our new statements at the end of conditional block before the |
| COND_STMT. */ |
| gsi = gsi_for_stmt (stmt); |
| new_var = force_gimple_operand_gsi (&gsi, cond, true, NULL, true, |
| GSI_SAME_STMT); |
| |
| if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (new_var))) |
| { |
| location_t locus_0, locus_1; |
| |
| new_var2 = make_ssa_name (TREE_TYPE (result)); |
| new_stmt = gimple_build_assign (new_var2, CONVERT_EXPR, new_var); |
| gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT); |
| new_var = new_var2; |
| |
| /* Set the locus to the first argument, unless is doesn't have one. */ |
| locus_0 = gimple_phi_arg_location (phi, 0); |
| locus_1 = gimple_phi_arg_location (phi, 1); |
| if (locus_0 == UNKNOWN_LOCATION) |
| locus_0 = locus_1; |
| gimple_set_location (new_stmt, locus_0); |
| } |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, new_var); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| |
| /* Update *ARG which is defined in STMT so that it contains the |
| computed value if that seems profitable. Return true if the |
| statement is made dead by that rewriting. */ |
| |
| static bool |
| jump_function_from_stmt (tree *arg, gimple *stmt) |
| { |
| enum tree_code code = gimple_assign_rhs_code (stmt); |
| if (code == ADDR_EXPR) |
| { |
| /* For arg = &p->i transform it to p, if possible. */ |
| tree rhs1 = gimple_assign_rhs1 (stmt); |
| poly_int64 offset; |
| tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs1, 0), |
| &offset); |
| if (tem |
| && TREE_CODE (tem) == MEM_REF |
| && known_eq (mem_ref_offset (tem) + offset, 0)) |
| { |
| *arg = TREE_OPERAND (tem, 0); |
| return true; |
| } |
| } |
| /* TODO: Much like IPA-CP jump-functions we want to handle constant |
| additions symbolically here, and we'd need to update the comparison |
| code that compares the arg + cst tuples in our caller. For now the |
| code above exactly handles the VEC_BASE pattern from vec.h. */ |
| return false; |
| } |
| |
| /* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional |
| of the form SSA_NAME NE 0. |
| |
| If RHS is fed by a simple EQ_EXPR comparison of two values, see if |
| the two input values of the EQ_EXPR match arg0 and arg1. |
| |
| If so update *code and return TRUE. Otherwise return FALSE. */ |
| |
| static bool |
| rhs_is_fed_for_value_replacement (const_tree arg0, const_tree arg1, |
| enum tree_code *code, const_tree rhs) |
| { |
| /* Obviously if RHS is not an SSA_NAME, we can't look at the defining |
| statement. */ |
| if (TREE_CODE (rhs) == SSA_NAME) |
| { |
| gimple *def1 = SSA_NAME_DEF_STMT (rhs); |
| |
| /* Verify the defining statement has an EQ_EXPR on the RHS. */ |
| if (is_gimple_assign (def1) && gimple_assign_rhs_code (def1) == EQ_EXPR) |
| { |
| /* Finally verify the source operands of the EQ_EXPR are equal |
| to arg0 and arg1. */ |
| tree op0 = gimple_assign_rhs1 (def1); |
| tree op1 = gimple_assign_rhs2 (def1); |
| if ((operand_equal_for_phi_arg_p (arg0, op0) |
| && operand_equal_for_phi_arg_p (arg1, op1)) |
| || (operand_equal_for_phi_arg_p (arg0, op1) |
| && operand_equal_for_phi_arg_p (arg1, op0))) |
| { |
| /* We will perform the optimization. */ |
| *code = gimple_assign_rhs_code (def1); |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| /* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND. |
| |
| Also return TRUE if arg0/arg1 are equal to the source arguments of a |
| an EQ comparison feeding a BIT_AND_EXPR which feeds COND. |
| |
| Return FALSE otherwise. */ |
| |
| static bool |
| operand_equal_for_value_replacement (const_tree arg0, const_tree arg1, |
| enum tree_code *code, gimple *cond) |
| { |
| gimple *def; |
| tree lhs = gimple_cond_lhs (cond); |
| tree rhs = gimple_cond_rhs (cond); |
| |
| if ((operand_equal_for_phi_arg_p (arg0, lhs) |
| && operand_equal_for_phi_arg_p (arg1, rhs)) |
| || (operand_equal_for_phi_arg_p (arg1, lhs) |
| && operand_equal_for_phi_arg_p (arg0, rhs))) |
| return true; |
| |
| /* Now handle more complex case where we have an EQ comparison |
| which feeds a BIT_AND_EXPR which feeds COND. |
| |
| First verify that COND is of the form SSA_NAME NE 0. */ |
| if (*code != NE_EXPR || !integer_zerop (rhs) |
| || TREE_CODE (lhs) != SSA_NAME) |
| return false; |
| |
| /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR. */ |
| def = SSA_NAME_DEF_STMT (lhs); |
| if (!is_gimple_assign (def) || gimple_assign_rhs_code (def) != BIT_AND_EXPR) |
| return false; |
| |
| /* Now verify arg0/arg1 correspond to the source arguments of an |
| EQ comparison feeding the BIT_AND_EXPR. */ |
| |
| tree tmp = gimple_assign_rhs1 (def); |
| if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp)) |
| return true; |
| |
| tmp = gimple_assign_rhs2 (def); |
| if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp)) |
| return true; |
| |
| return false; |
| } |
| |
| /* Returns true if ARG is a neutral element for operation CODE |
| on the RIGHT side. */ |
| |
| static bool |
| neutral_element_p (tree_code code, tree arg, bool right) |
| { |
| switch (code) |
| { |
| case PLUS_EXPR: |
| case BIT_IOR_EXPR: |
| case BIT_XOR_EXPR: |
| return integer_zerop (arg); |
| |
| case LROTATE_EXPR: |
| case RROTATE_EXPR: |
| case LSHIFT_EXPR: |
| case RSHIFT_EXPR: |
| case MINUS_EXPR: |
| case POINTER_PLUS_EXPR: |
| return right && integer_zerop (arg); |
| |
| case MULT_EXPR: |
| return integer_onep (arg); |
| |
| case TRUNC_DIV_EXPR: |
| case CEIL_DIV_EXPR: |
| case FLOOR_DIV_EXPR: |
| case ROUND_DIV_EXPR: |
| case EXACT_DIV_EXPR: |
| return right && integer_onep (arg); |
| |
| case BIT_AND_EXPR: |
| return integer_all_onesp (arg); |
| |
| default: |
| return false; |
| } |
| } |
| |
| /* Returns true if ARG is an absorbing element for operation CODE. */ |
| |
| static bool |
| absorbing_element_p (tree_code code, tree arg, bool right, tree rval) |
| { |
| switch (code) |
| { |
| case BIT_IOR_EXPR: |
| return integer_all_onesp (arg); |
| |
| case MULT_EXPR: |
| case BIT_AND_EXPR: |
| return integer_zerop (arg); |
| |
| case LSHIFT_EXPR: |
| case RSHIFT_EXPR: |
| case LROTATE_EXPR: |
| case RROTATE_EXPR: |
| return !right && integer_zerop (arg); |
| |
| case TRUNC_DIV_EXPR: |
| case CEIL_DIV_EXPR: |
| case FLOOR_DIV_EXPR: |
| case ROUND_DIV_EXPR: |
| case EXACT_DIV_EXPR: |
| case TRUNC_MOD_EXPR: |
| case CEIL_MOD_EXPR: |
| case FLOOR_MOD_EXPR: |
| case ROUND_MOD_EXPR: |
| return (!right |
| && integer_zerop (arg) |
| && tree_single_nonzero_warnv_p (rval, NULL)); |
| |
| default: |
| return false; |
| } |
| } |
| |
| /* The function value_replacement does the main work of doing the value |
| replacement. Return non-zero if the replacement is done. Otherwise return |
| 0. If we remove the middle basic block, return 2. |
| BB is the basic block where the replacement is going to be done on. ARG0 |
| is argument 0 from the PHI. Likewise for ARG1. */ |
| |
| static int |
| value_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e0, edge e1, gimple *phi, |
| tree arg0, tree arg1) |
| { |
| gimple_stmt_iterator gsi; |
| gimple *cond; |
| edge true_edge, false_edge; |
| enum tree_code code; |
| bool empty_or_with_defined_p = true; |
| |
| /* If the type says honor signed zeros we cannot do this |
| optimization. */ |
| if (HONOR_SIGNED_ZEROS (arg1)) |
| return 0; |
| |
| /* If there is a statement in MIDDLE_BB that defines one of the PHI |
| arguments, then adjust arg0 or arg1. */ |
| gsi = gsi_start_nondebug_after_labels_bb (middle_bb); |
| while (!gsi_end_p (gsi)) |
| { |
| gimple *stmt = gsi_stmt (gsi); |
| tree lhs; |
| gsi_next_nondebug (&gsi); |
| if (!is_gimple_assign (stmt)) |
| { |
| if (gimple_code (stmt) != GIMPLE_PREDICT |
| && gimple_code (stmt) != GIMPLE_NOP) |
| empty_or_with_defined_p = false; |
| continue; |
| } |
| /* Now try to adjust arg0 or arg1 according to the computation |
| in the statement. */ |
| lhs = gimple_assign_lhs (stmt); |
| if (!(lhs == arg0 |
| && jump_function_from_stmt (&arg0, stmt)) |
| || (lhs == arg1 |
| && jump_function_from_stmt (&arg1, stmt))) |
| empty_or_with_defined_p = false; |
| } |
| |
| cond = last_stmt (cond_bb); |
| code = gimple_cond_code (cond); |
| |
| /* This transformation is only valid for equality comparisons. */ |
| if (code != NE_EXPR && code != EQ_EXPR) |
| return 0; |
| |
| /* We need to know which is the true edge and which is the false |
| edge so that we know if have abs or negative abs. */ |
| extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
| |
| /* At this point we know we have a COND_EXPR with two successors. |
| One successor is BB, the other successor is an empty block which |
| falls through into BB. |
| |
| The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR. |
| |
| There is a single PHI node at the join point (BB) with two arguments. |
| |
| We now need to verify that the two arguments in the PHI node match |
| the two arguments to the equality comparison. */ |
| |
| if (operand_equal_for_value_replacement (arg0, arg1, &code, cond)) |
| { |
| edge e; |
| tree arg; |
| |
| /* For NE_EXPR, we want to build an assignment result = arg where |
| arg is the PHI argument associated with the true edge. For |
| EQ_EXPR we want the PHI argument associated with the false edge. */ |
| e = (code == NE_EXPR ? true_edge : false_edge); |
| |
| /* Unfortunately, E may not reach BB (it may instead have gone to |
| OTHER_BLOCK). If that is the case, then we want the single outgoing |
| edge from OTHER_BLOCK which reaches BB and represents the desired |
| path from COND_BLOCK. */ |
| if (e->dest == middle_bb) |
| e = single_succ_edge (e->dest); |
| |
| /* Now we know the incoming edge to BB that has the argument for the |
| RHS of our new assignment statement. */ |
| if (e0 == e) |
| arg = arg0; |
| else |
| arg = arg1; |
| |
| /* If the middle basic block was empty or is defining the |
| PHI arguments and this is a single phi where the args are different |
| for the edges e0 and e1 then we can remove the middle basic block. */ |
| if (empty_or_with_defined_p |
| && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)), |
| e0, e1) == phi) |
| { |
| replace_phi_edge_with_variable (cond_bb, e1, phi, arg); |
| /* Note that we optimized this PHI. */ |
| return 2; |
| } |
| else |
| { |
| /* Replace the PHI arguments with arg. */ |
| SET_PHI_ARG_DEF (phi, e0->dest_idx, arg); |
| SET_PHI_ARG_DEF (phi, e1->dest_idx, arg); |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "PHI "); |
| print_generic_expr (dump_file, gimple_phi_result (phi)); |
| fprintf (dump_file, " reduced for COND_EXPR in block %d to ", |
| cond_bb->index); |
| print_generic_expr (dump_file, arg); |
| fprintf (dump_file, ".\n"); |
| } |
| return 1; |
| } |
| |
| } |
| |
| /* Now optimize (x != 0) ? x + y : y to just x + y. */ |
| gsi = gsi_last_nondebug_bb (middle_bb); |
| if (gsi_end_p (gsi)) |
| return 0; |
| |
| gimple *assign = gsi_stmt (gsi); |
| if (!is_gimple_assign (assign) |
| || gimple_assign_rhs_class (assign) != GIMPLE_BINARY_RHS |
| || (!INTEGRAL_TYPE_P (TREE_TYPE (arg0)) |
| && !POINTER_TYPE_P (TREE_TYPE (arg0)))) |
| return 0; |
| |
| /* Punt if there are (degenerate) PHIs in middle_bb, there should not be. */ |
| if (!gimple_seq_empty_p (phi_nodes (middle_bb))) |
| return 0; |
| |
| /* Allow up to 2 cheap preparation statements that prepare argument |
| for assign, e.g.: |
| if (y_4 != 0) |
| goto <bb 3>; |
| else |
| goto <bb 4>; |
| <bb 3>: |
| _1 = (int) y_4; |
| iftmp.0_6 = x_5(D) r<< _1; |
| <bb 4>: |
| # iftmp.0_2 = PHI <iftmp.0_6(3), x_5(D)(2)> |
| or: |
| if (y_3(D) == 0) |
| goto <bb 4>; |
| else |
| goto <bb 3>; |
| <bb 3>: |
| y_4 = y_3(D) & 31; |
| _1 = (int) y_4; |
| _6 = x_5(D) r<< _1; |
| <bb 4>: |
| # _2 = PHI <x_5(D)(2), _6(3)> */ |
| gimple *prep_stmt[2] = { NULL, NULL }; |
| int prep_cnt; |
| for (prep_cnt = 0; ; prep_cnt++) |
| { |
| gsi_prev_nondebug (&gsi); |
| if (gsi_end_p (gsi)) |
| break; |
| |
| gimple *g = gsi_stmt (gsi); |
| if (gimple_code (g) == GIMPLE_LABEL) |
| break; |
| |
| if (prep_cnt == 2 || !is_gimple_assign (g)) |
| return 0; |
| |
| tree lhs = gimple_assign_lhs (g); |
| tree rhs1 = gimple_assign_rhs1 (g); |
| use_operand_p use_p; |
| gimple *use_stmt; |
| if (TREE_CODE (lhs) != SSA_NAME |
| || TREE_CODE (rhs1) != SSA_NAME |
| || !INTEGRAL_TYPE_P (TREE_TYPE (lhs)) |
| || !INTEGRAL_TYPE_P (TREE_TYPE (rhs1)) |
| || !single_imm_use (lhs, &use_p, &use_stmt) |
| || use_stmt != (prep_cnt ? prep_stmt[prep_cnt - 1] : assign)) |
| return 0; |
| switch (gimple_assign_rhs_code (g)) |
| { |
| CASE_CONVERT: |
| break; |
| case PLUS_EXPR: |
| case BIT_AND_EXPR: |
| case BIT_IOR_EXPR: |
| case BIT_XOR_EXPR: |
| if (TREE_CODE (gimple_assign_rhs2 (g)) != INTEGER_CST) |
| return 0; |
| break; |
| default: |
| return 0; |
| } |
| prep_stmt[prep_cnt] = g; |
| } |
| |
| /* Only transform if it removes the condition. */ |
| if (!single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)), e0, e1)) |
| return 0; |
| |
| /* Size-wise, this is always profitable. */ |
| if (optimize_bb_for_speed_p (cond_bb) |
| /* The special case is useless if it has a low probability. */ |
| && profile_status_for_fn (cfun) != PROFILE_ABSENT |
| && EDGE_PRED (middle_bb, 0)->probability < profile_probability::even () |
| /* If assign is cheap, there is no point avoiding it. */ |
| && estimate_num_insns_seq (bb_seq (middle_bb), &eni_time_weights) |
| >= 3 * estimate_num_insns (cond, &eni_time_weights)) |
| return 0; |
| |
| tree lhs = gimple_assign_lhs (assign); |
| tree rhs1 = gimple_assign_rhs1 (assign); |
| tree rhs2 = gimple_assign_rhs2 (assign); |
| enum tree_code code_def = gimple_assign_rhs_code (assign); |
| tree cond_lhs = gimple_cond_lhs (cond); |
| tree cond_rhs = gimple_cond_rhs (cond); |
| |
| /* Propagate the cond_rhs constant through preparation stmts, |
| make sure UB isn't invoked while doing that. */ |
| for (int i = prep_cnt - 1; i >= 0; --i) |
| { |
| gimple *g = prep_stmt[i]; |
| tree grhs1 = gimple_assign_rhs1 (g); |
| if (!operand_equal_for_phi_arg_p (cond_lhs, grhs1)) |
| return 0; |
| cond_lhs = gimple_assign_lhs (g); |
| cond_rhs = fold_convert (TREE_TYPE (grhs1), cond_rhs); |
| if (TREE_CODE (cond_rhs) != INTEGER_CST |
| || TREE_OVERFLOW (cond_rhs)) |
| return 0; |
| if (gimple_assign_rhs_class (g) == GIMPLE_BINARY_RHS) |
| { |
| cond_rhs = int_const_binop (gimple_assign_rhs_code (g), cond_rhs, |
| gimple_assign_rhs2 (g)); |
| if (TREE_OVERFLOW (cond_rhs)) |
| return 0; |
| } |
| cond_rhs = fold_convert (TREE_TYPE (cond_lhs), cond_rhs); |
| if (TREE_CODE (cond_rhs) != INTEGER_CST |
| || TREE_OVERFLOW (cond_rhs)) |
| return 0; |
| } |
| |
| if (((code == NE_EXPR && e1 == false_edge) |
| || (code == EQ_EXPR && e1 == true_edge)) |
| && arg0 == lhs |
| && ((arg1 == rhs1 |
| && operand_equal_for_phi_arg_p (rhs2, cond_lhs) |
| && neutral_element_p (code_def, cond_rhs, true)) |
| || (arg1 == rhs2 |
| && operand_equal_for_phi_arg_p (rhs1, cond_lhs) |
| && neutral_element_p (code_def, cond_rhs, false)) |
| || (operand_equal_for_phi_arg_p (arg1, cond_rhs) |
| && ((operand_equal_for_phi_arg_p (rhs2, cond_lhs) |
| && absorbing_element_p (code_def, cond_rhs, true, rhs2)) |
| || (operand_equal_for_phi_arg_p (rhs1, cond_lhs) |
| && absorbing_element_p (code_def, |
| cond_rhs, false, rhs2)))))) |
| { |
| gsi = gsi_for_stmt (cond); |
| /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6 |
| def-stmt in: |
| if (n_5 != 0) |
| goto <bb 3>; |
| else |
| goto <bb 4>; |
| |
| <bb 3>: |
| # RANGE [0, 4294967294] |
| u_6 = n_5 + 4294967295; |
| |
| <bb 4>: |
| # u_3 = PHI <u_6(3), 4294967295(2)> */ |
| reset_flow_sensitive_info (lhs); |
| if (INTEGRAL_TYPE_P (TREE_TYPE (lhs))) |
| { |
| /* If available, we can use VR of phi result at least. */ |
| tree phires = gimple_phi_result (phi); |
| struct range_info_def *phires_range_info |
| = SSA_NAME_RANGE_INFO (phires); |
| if (phires_range_info) |
| duplicate_ssa_name_range_info (lhs, SSA_NAME_RANGE_TYPE (phires), |
| phires_range_info); |
| } |
| gimple_stmt_iterator gsi_from; |
| for (int i = prep_cnt - 1; i >= 0; --i) |
| { |
| tree plhs = gimple_assign_lhs (prep_stmt[i]); |
| reset_flow_sensitive_info (plhs); |
| gsi_from = gsi_for_stmt (prep_stmt[i]); |
| gsi_move_before (&gsi_from, &gsi); |
| } |
| gsi_from = gsi_for_stmt (assign); |
| gsi_move_before (&gsi_from, &gsi); |
| replace_phi_edge_with_variable (cond_bb, e1, phi, lhs); |
| return 2; |
| } |
| |
| return 0; |
| } |
| |
| /* The function minmax_replacement does the main work of doing the minmax |
| replacement. Return true if the replacement is done. Otherwise return |
| false. |
| BB is the basic block where the replacement is going to be done on. ARG0 |
| is argument 0 from the PHI. Likewise for ARG1. */ |
| |
| static bool |
| minmax_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e0, edge e1, gimple *phi, |
| tree arg0, tree arg1) |
| { |
| tree result; |
| edge true_edge, false_edge; |
| enum tree_code minmax, ass_code; |
| tree smaller, larger, arg_true, arg_false; |
| gimple_stmt_iterator gsi, gsi_from; |
| |
| tree type = TREE_TYPE (PHI_RESULT (phi)); |
| |
| /* The optimization may be unsafe due to NaNs. */ |
| if (HONOR_NANS (type) || HONOR_SIGNED_ZEROS (type)) |
| return false; |
| |
| gcond *cond = as_a <gcond *> (last_stmt (cond_bb)); |
| enum tree_code cmp = gimple_cond_code (cond); |
| tree rhs = gimple_cond_rhs (cond); |
| |
| /* Turn EQ/NE of extreme values to order comparisons. */ |
| if ((cmp == NE_EXPR || cmp == EQ_EXPR) |
| && TREE_CODE (rhs) == INTEGER_CST |
| && INTEGRAL_TYPE_P (TREE_TYPE (rhs))) |
| { |
| if (wi::eq_p (wi::to_wide (rhs), wi::min_value (TREE_TYPE (rhs)))) |
| { |
| cmp = (cmp == EQ_EXPR) ? LT_EXPR : GE_EXPR; |
| rhs = wide_int_to_tree (TREE_TYPE (rhs), |
| wi::min_value (TREE_TYPE (rhs)) + 1); |
| } |
| else if (wi::eq_p (wi::to_wide (rhs), wi::max_value (TREE_TYPE (rhs)))) |
| { |
| cmp = (cmp == EQ_EXPR) ? GT_EXPR : LE_EXPR; |
| rhs = wide_int_to_tree (TREE_TYPE (rhs), |
| wi::max_value (TREE_TYPE (rhs)) - 1); |
| } |
| } |
| |
| /* This transformation is only valid for order comparisons. Record which |
| operand is smaller/larger if the result of the comparison is true. */ |
| tree alt_smaller = NULL_TREE; |
| tree alt_larger = NULL_TREE; |
| if (cmp == LT_EXPR || cmp == LE_EXPR) |
| { |
| smaller = gimple_cond_lhs (cond); |
| larger = rhs; |
| /* If we have smaller < CST it is equivalent to smaller <= CST-1. |
| Likewise smaller <= CST is equivalent to smaller < CST+1. */ |
| if (TREE_CODE (larger) == INTEGER_CST |
| && INTEGRAL_TYPE_P (TREE_TYPE (larger))) |
| { |
| if (cmp == LT_EXPR) |
| { |
| wi::overflow_type overflow; |
| wide_int alt = wi::sub (wi::to_wide (larger), 1, |
| TYPE_SIGN (TREE_TYPE (larger)), |
| &overflow); |
| if (! overflow) |
| alt_larger = wide_int_to_tree (TREE_TYPE (larger), alt); |
| } |
| else |
| { |
| wi::overflow_type overflow; |
| wide_int alt = wi::add (wi::to_wide (larger), 1, |
| TYPE_SIGN (TREE_TYPE (larger)), |
| &overflow); |
| if (! overflow) |
| alt_larger = wide_int_to_tree (TREE_TYPE (larger), alt); |
| } |
| } |
| } |
| else if (cmp == GT_EXPR || cmp == GE_EXPR) |
| { |
| smaller = rhs; |
| larger = gimple_cond_lhs (cond); |
| /* If we have larger > CST it is equivalent to larger >= CST+1. |
| Likewise larger >= CST is equivalent to larger > CST-1. */ |
| if (TREE_CODE (smaller) == INTEGER_CST |
| && INTEGRAL_TYPE_P (TREE_TYPE (smaller))) |
| { |
| wi::overflow_type overflow; |
| if (cmp == GT_EXPR) |
| { |
| wide_int alt = wi::add (wi::to_wide (smaller), 1, |
| TYPE_SIGN (TREE_TYPE (smaller)), |
| &overflow); |
| if (! overflow) |
| alt_smaller = wide_int_to_tree (TREE_TYPE (smaller), alt); |
| } |
| else |
| { |
| wide_int alt = wi::sub (wi::to_wide (smaller), 1, |
| TYPE_SIGN (TREE_TYPE (smaller)), |
| &overflow); |
| if (! overflow) |
| alt_smaller = wide_int_to_tree (TREE_TYPE (smaller), alt); |
| } |
| } |
| } |
| else |
| return false; |
| |
| /* Handle the special case of (signed_type)x < 0 being equivalent |
| to x > MAX_VAL(signed_type) and (signed_type)x >= 0 equivalent |
| to x <= MAX_VAL(signed_type). */ |
| if ((cmp == GE_EXPR || cmp == LT_EXPR) |
| && INTEGRAL_TYPE_P (type) |
| && TYPE_UNSIGNED (type) |
| && integer_zerop (rhs)) |
| { |
| tree op = gimple_cond_lhs (cond); |
| if (TREE_CODE (op) == SSA_NAME |
| && INTEGRAL_TYPE_P (TREE_TYPE (op)) |
| && !TYPE_UNSIGNED (TREE_TYPE (op))) |
| { |
| gimple *def_stmt = SSA_NAME_DEF_STMT (op); |
| if (gimple_assign_cast_p (def_stmt)) |
| { |
| tree op1 = gimple_assign_rhs1 (def_stmt); |
| if (INTEGRAL_TYPE_P (TREE_TYPE (op1)) |
| && TYPE_UNSIGNED (TREE_TYPE (op1)) |
| && (TYPE_PRECISION (TREE_TYPE (op)) |
| == TYPE_PRECISION (TREE_TYPE (op1))) |
| && useless_type_conversion_p (type, TREE_TYPE (op1))) |
| { |
| wide_int w1 = wi::max_value (TREE_TYPE (op)); |
| wide_int w2 = wi::add (w1, 1); |
| if (cmp == LT_EXPR) |
| { |
| larger = op1; |
| smaller = wide_int_to_tree (TREE_TYPE (op1), w1); |
| alt_smaller = wide_int_to_tree (TREE_TYPE (op1), w2); |
| alt_larger = NULL_TREE; |
| } |
| else |
| { |
| smaller = op1; |
| larger = wide_int_to_tree (TREE_TYPE (op1), w1); |
| alt_larger = wide_int_to_tree (TREE_TYPE (op1), w2); |
| alt_smaller = NULL_TREE; |
| } |
| } |
| } |
| } |
| } |
| |
| /* We need to know which is the true edge and which is the false |
| edge so that we know if have abs or negative abs. */ |
| extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
| |
| /* Forward the edges over the middle basic block. */ |
| if (true_edge->dest == middle_bb) |
| true_edge = EDGE_SUCC (true_edge->dest, 0); |
| if (false_edge->dest == middle_bb) |
| false_edge = EDGE_SUCC (false_edge->dest, 0); |
| |
| if (true_edge == e0) |
| { |
| gcc_assert (false_edge == e1); |
| arg_true = arg0; |
| arg_false = arg1; |
| } |
| else |
| { |
| gcc_assert (false_edge == e0); |
| gcc_assert (true_edge == e1); |
| arg_true = arg1; |
| arg_false = arg0; |
| } |
| |
| if (empty_block_p (middle_bb)) |
| { |
| if ((operand_equal_for_phi_arg_p (arg_true, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (arg_true, alt_smaller))) |
| && (operand_equal_for_phi_arg_p (arg_false, larger) |
| || (alt_larger |
| && operand_equal_for_phi_arg_p (arg_true, alt_larger)))) |
| { |
| /* Case |
| |
| if (smaller < larger) |
| rslt = smaller; |
| else |
| rslt = larger; */ |
| minmax = MIN_EXPR; |
| } |
| else if ((operand_equal_for_phi_arg_p (arg_false, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (arg_false, alt_smaller))) |
| && (operand_equal_for_phi_arg_p (arg_true, larger) |
| || (alt_larger |
| && operand_equal_for_phi_arg_p (arg_true, alt_larger)))) |
| minmax = MAX_EXPR; |
| else |
| return false; |
| } |
| else |
| { |
| /* Recognize the following case, assuming d <= u: |
| |
| if (a <= u) |
| b = MAX (a, d); |
| x = PHI <b, u> |
| |
| This is equivalent to |
| |
| b = MAX (a, d); |
| x = MIN (b, u); */ |
| |
| gimple *assign = last_and_only_stmt (middle_bb); |
| tree lhs, op0, op1, bound; |
| |
| if (!assign |
| || gimple_code (assign) != GIMPLE_ASSIGN) |
| return false; |
| |
| lhs = gimple_assign_lhs (assign); |
| ass_code = gimple_assign_rhs_code (assign); |
| if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) |
| return false; |
| op0 = gimple_assign_rhs1 (assign); |
| op1 = gimple_assign_rhs2 (assign); |
| |
| if (true_edge->src == middle_bb) |
| { |
| /* We got here if the condition is true, i.e., SMALLER < LARGER. */ |
| if (!operand_equal_for_phi_arg_p (lhs, arg_true)) |
| return false; |
| |
| if (operand_equal_for_phi_arg_p (arg_false, larger) |
| || (alt_larger |
| && operand_equal_for_phi_arg_p (arg_false, alt_larger))) |
| { |
| /* Case |
| |
| if (smaller < larger) |
| { |
| r' = MAX_EXPR (smaller, bound) |
| } |
| r = PHI <r', larger> --> to be turned to MIN_EXPR. */ |
| if (ass_code != MAX_EXPR) |
| return false; |
| |
| minmax = MIN_EXPR; |
| if (operand_equal_for_phi_arg_p (op0, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (op0, alt_smaller))) |
| bound = op1; |
| else if (operand_equal_for_phi_arg_p (op1, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (op1, alt_smaller))) |
| bound = op0; |
| else |
| return false; |
| |
| /* We need BOUND <= LARGER. */ |
| if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, |
| bound, larger))) |
| return false; |
| } |
| else if (operand_equal_for_phi_arg_p (arg_false, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (arg_false, alt_smaller))) |
| { |
| /* Case |
| |
| if (smaller < larger) |
| { |
| r' = MIN_EXPR (larger, bound) |
| } |
| r = PHI <r', smaller> --> to be turned to MAX_EXPR. */ |
| if (ass_code != MIN_EXPR) |
| return false; |
| |
| minmax = MAX_EXPR; |
| if (operand_equal_for_phi_arg_p (op0, larger) |
| || (alt_larger |
| && operand_equal_for_phi_arg_p (op0, alt_larger))) |
| bound = op1; |
| else if (operand_equal_for_phi_arg_p (op1, larger) |
| || (alt_larger |
| && operand_equal_for_phi_arg_p (op1, alt_larger))) |
| bound = op0; |
| else |
| return false; |
| |
| /* We need BOUND >= SMALLER. */ |
| if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, |
| bound, smaller))) |
| return false; |
| } |
| else |
| return false; |
| } |
| else |
| { |
| /* We got here if the condition is false, i.e., SMALLER > LARGER. */ |
| if (!operand_equal_for_phi_arg_p (lhs, arg_false)) |
| return false; |
| |
| if (operand_equal_for_phi_arg_p (arg_true, larger) |
| || (alt_larger |
| && operand_equal_for_phi_arg_p (arg_true, alt_larger))) |
| { |
| /* Case |
| |
| if (smaller > larger) |
| { |
| r' = MIN_EXPR (smaller, bound) |
| } |
| r = PHI <r', larger> --> to be turned to MAX_EXPR. */ |
| if (ass_code != MIN_EXPR) |
| return false; |
| |
| minmax = MAX_EXPR; |
| if (operand_equal_for_phi_arg_p (op0, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (op0, alt_smaller))) |
| bound = op1; |
| else if (operand_equal_for_phi_arg_p (op1, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (op1, alt_smaller))) |
| bound = op0; |
| else |
| return false; |
| |
| /* We need BOUND >= LARGER. */ |
| if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, |
| bound, larger))) |
| return false; |
| } |
| else if (operand_equal_for_phi_arg_p (arg_true, smaller) |
| || (alt_smaller |
| && operand_equal_for_phi_arg_p (arg_true, alt_smaller))) |
| { |
| /* Case |
| |
| if (smaller > larger) |
| { |
| r' = MAX_EXPR (larger, bound) |
| } |
| r = PHI <r', smaller> --> to be turned to MIN_EXPR. */ |
| if (ass_code != MAX_EXPR) |
| return false; |
| |
| minmax = MIN_EXPR; |
| if (operand_equal_for_phi_arg_p (op0, larger)) |
| bound = op1; |
| else if (operand_equal_for_phi_arg_p (op1, larger)) |
| bound = op0; |
| else |
| return false; |
| |
| /* We need BOUND <= SMALLER. */ |
| if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, |
| bound, smaller))) |
| return false; |
| } |
| else |
| return false; |
| } |
| |
| /* Move the statement from the middle block. */ |
| gsi = gsi_last_bb (cond_bb); |
| gsi_from = gsi_last_nondebug_bb (middle_bb); |
| reset_flow_sensitive_info (SINGLE_SSA_TREE_OPERAND (gsi_stmt (gsi_from), |
| SSA_OP_DEF)); |
| gsi_move_before (&gsi_from, &gsi); |
| } |
| |
| /* Emit the statement to compute min/max. */ |
| gimple_seq stmts = NULL; |
| tree phi_result = PHI_RESULT (phi); |
| result = gimple_build (&stmts, minmax, TREE_TYPE (phi_result), arg0, arg1); |
| /* Duplicate range info if we're the only things setting the target PHI. */ |
| if (!gimple_seq_empty_p (stmts) |
| && EDGE_COUNT (gimple_bb (phi)->preds) == 2 |
| && !POINTER_TYPE_P (TREE_TYPE (phi_result)) |
| && SSA_NAME_RANGE_INFO (phi_result)) |
| duplicate_ssa_name_range_info (result, SSA_NAME_RANGE_TYPE (phi_result), |
| SSA_NAME_RANGE_INFO (phi_result)); |
| |
| gsi = gsi_last_bb (cond_bb); |
| gsi_insert_seq_before (&gsi, stmts, GSI_NEW_STMT); |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
| |
| return true; |
| } |
| |
| /* Convert |
| |
| <bb 2> |
| if (b_4(D) != 0) |
| goto <bb 3> |
| else |
| goto <bb 4> |
| |
| <bb 3> |
| _2 = (unsigned long) b_4(D); |
| _9 = __builtin_popcountl (_2); |
| OR |
| _9 = __builtin_popcountl (b_4(D)); |
| |
| <bb 4> |
| c_12 = PHI <0(2), _9(3)> |
| |
| Into |
| <bb 2> |
| _2 = (unsigned long) b_4(D); |
| _9 = __builtin_popcountl (_2); |
| OR |
| _9 = __builtin_popcountl (b_4(D)); |
| |
| <bb 4> |
| c_12 = PHI <_9(2)> |
| |
| Similarly for __builtin_clz or __builtin_ctz if |
| C?Z_DEFINED_VALUE_AT_ZERO is 2, optab is present and |
| instead of 0 above it uses the value from that macro. */ |
| |
| static bool |
| cond_removal_in_popcount_clz_ctz_pattern (basic_block cond_bb, |
| basic_block middle_bb, |
| edge e1, edge e2, gimple *phi, |
| tree arg0, tree arg1) |
| { |
| gimple *cond; |
| gimple_stmt_iterator gsi, gsi_from; |
| gimple *call; |
| gimple *cast = NULL; |
| tree lhs, arg; |
| |
| /* Check that |
| _2 = (unsigned long) b_4(D); |
| _9 = __builtin_popcountl (_2); |
| OR |
| _9 = __builtin_popcountl (b_4(D)); |
| are the only stmts in the middle_bb. */ |
| |
| gsi = gsi_start_nondebug_after_labels_bb (middle_bb); |
| if (gsi_end_p (gsi)) |
| return false; |
| cast = gsi_stmt (gsi); |
| gsi_next_nondebug (&gsi); |
| if (!gsi_end_p (gsi)) |
| { |
| call = gsi_stmt (gsi); |
| gsi_next_nondebug (&gsi); |
| if (!gsi_end_p (gsi)) |
| return false; |
| } |
| else |
| { |
| call = cast; |
| cast = NULL; |
| } |
| |
| /* Check that we have a popcount/clz/ctz builtin. */ |
| if (!is_gimple_call (call) || gimple_call_num_args (call) != 1) |
| return false; |
| |
| arg = gimple_call_arg (call, 0); |
| lhs = gimple_get_lhs (call); |
| |
| if (lhs == NULL_TREE) |
| return false; |
| |
| combined_fn cfn = gimple_call_combined_fn (call); |
| internal_fn ifn = IFN_LAST; |
| int val = 0; |
| switch (cfn) |
| { |
| CASE_CFN_POPCOUNT: |
| break; |
| CASE_CFN_CLZ: |
| if (INTEGRAL_TYPE_P (TREE_TYPE (arg))) |
| { |
| tree type = TREE_TYPE (arg); |
| if (direct_internal_fn_supported_p (IFN_CLZ, type, OPTIMIZE_FOR_BOTH) |
| && CLZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type), |
| val) == 2) |
| { |
| ifn = IFN_CLZ; |
| break; |
| } |
| } |
| return false; |
| CASE_CFN_CTZ: |
| if (INTEGRAL_TYPE_P (TREE_TYPE (arg))) |
| { |
| tree type = TREE_TYPE (arg); |
| if (direct_internal_fn_supported_p (IFN_CTZ, type, OPTIMIZE_FOR_BOTH) |
| && CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type), |
| val) == 2) |
| { |
| ifn = IFN_CTZ; |
| break; |
| } |
| } |
| return false; |
| default: |
| return false; |
| } |
| |
| if (cast) |
| { |
| /* We have a cast stmt feeding popcount/clz/ctz builtin. */ |
| /* Check that we have a cast prior to that. */ |
| if (gimple_code (cast) != GIMPLE_ASSIGN |
| || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (cast))) |
| return false; |
| /* Result of the cast stmt is the argument to the builtin. */ |
| if (arg != gimple_assign_lhs (cast)) |
| return false; |
| arg = gimple_assign_rhs1 (cast); |
| } |
| |
| cond = last_stmt (cond_bb); |
| |
| /* Cond_bb has a check for b_4 [!=|==] 0 before calling the popcount/clz/ctz |
| builtin. */ |
| if (gimple_code (cond) != GIMPLE_COND |
| || (gimple_cond_code (cond) != NE_EXPR |
| && gimple_cond_code (cond) != EQ_EXPR) |
| || !integer_zerop (gimple_cond_rhs (cond)) |
| || arg != gimple_cond_lhs (cond)) |
| return false; |
| |
| /* Canonicalize. */ |
| if ((e2->flags & EDGE_TRUE_VALUE |
| && gimple_cond_code (cond) == NE_EXPR) |
| || (e1->flags & EDGE_TRUE_VALUE |
| && gimple_cond_code (cond) == EQ_EXPR)) |
| { |
| std::swap (arg0, arg1); |
| std::swap (e1, e2); |
| } |
| |
| /* Check PHI arguments. */ |
| if (lhs != arg0 |
| || TREE_CODE (arg1) != INTEGER_CST |
| || wi::to_wide (arg1) != val) |
| return false; |
| |
| /* And insert the popcount/clz/ctz builtin and cast stmt before the |
| cond_bb. */ |
| gsi = gsi_last_bb (cond_bb); |
| if (cast) |
| { |
| gsi_from = gsi_for_stmt (cast); |
| gsi_move_before (&gsi_from, &gsi); |
| reset_flow_sensitive_info (gimple_get_lhs (cast)); |
| } |
| gsi_from = gsi_for_stmt (call); |
| if (ifn == IFN_LAST || gimple_call_internal_p (call)) |
| gsi_move_before (&gsi_from, &gsi); |
| else |
| { |
| /* For __builtin_c[lt]z* force .C[LT]Z ifn, because only |
| the latter is well defined at zero. */ |
| call = gimple_build_call_internal (ifn, 1, gimple_call_arg (call, 0)); |
| gimple_call_set_lhs (call, lhs); |
| gsi_insert_before (&gsi, call, GSI_SAME_STMT); |
| gsi_remove (&gsi_from, true); |
| } |
| reset_flow_sensitive_info (lhs); |
| |
| /* Now update the PHI and remove unneeded bbs. */ |
| replace_phi_edge_with_variable (cond_bb, e2, phi, lhs); |
| return true; |
| } |
| |
| /* The function absolute_replacement does the main work of doing the absolute |
| replacement. Return true if the replacement is done. Otherwise return |
| false. |
| bb is the basic block where the replacement is going to be done on. arg0 |
| is argument 0 from the phi. Likewise for arg1. */ |
| |
| static bool |
| abs_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e0 ATTRIBUTE_UNUSED, edge e1, |
| gimple *phi, tree arg0, tree arg1) |
| { |
| tree result; |
| gassign *new_stmt; |
| gimple *cond; |
| gimple_stmt_iterator gsi; |
| edge true_edge, false_edge; |
| gimple *assign; |
| edge e; |
| tree rhs, lhs; |
| bool negate; |
| enum tree_code cond_code; |
| |
| /* If the type says honor signed zeros we cannot do this |
| optimization. */ |
| if (HONOR_SIGNED_ZEROS (arg1)) |
| return false; |
| |
| /* OTHER_BLOCK must have only one executable statement which must have the |
| form arg0 = -arg1 or arg1 = -arg0. */ |
| |
| assign = last_and_only_stmt (middle_bb); |
| /* If we did not find the proper negation assignment, then we cannot |
| optimize. */ |
| if (assign == NULL) |
| return false; |
| |
| /* If we got here, then we have found the only executable statement |
| in OTHER_BLOCK. If it is anything other than arg = -arg1 or |
| arg1 = -arg0, then we cannot optimize. */ |
| if (gimple_code (assign) != GIMPLE_ASSIGN) |
| return false; |
| |
| lhs = gimple_assign_lhs (assign); |
| |
| if (gimple_assign_rhs_code (assign) != NEGATE_EXPR) |
| return false; |
| |
| rhs = gimple_assign_rhs1 (assign); |
| |
| /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ |
| if (!(lhs == arg0 && rhs == arg1) |
| && !(lhs == arg1 && rhs == arg0)) |
| return false; |
| |
| cond = last_stmt (cond_bb); |
| result = PHI_RESULT (phi); |
| |
| /* Only relationals comparing arg[01] against zero are interesting. */ |
| cond_code = gimple_cond_code (cond); |
| if (cond_code != GT_EXPR && cond_code != GE_EXPR |
| && cond_code != LT_EXPR && cond_code != LE_EXPR) |
| return false; |
| |
| /* Make sure the conditional is arg[01] OP y. */ |
| if (gimple_cond_lhs (cond) != rhs) |
| return false; |
| |
| if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond))) |
| ? real_zerop (gimple_cond_rhs (cond)) |
| : integer_zerop (gimple_cond_rhs (cond))) |
| ; |
| else |
| return false; |
| |
| /* We need to know which is the true edge and which is the false |
| edge so that we know if have abs or negative abs. */ |
| extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
| |
| /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we |
| will need to negate the result. Similarly for LT_EXPR/LE_EXPR if |
| the false edge goes to OTHER_BLOCK. */ |
| if (cond_code == GT_EXPR || cond_code == GE_EXPR) |
| e = true_edge; |
| else |
| e = false_edge; |
| |
| if (e->dest == middle_bb) |
| negate = true; |
| else |
| negate = false; |
| |
| /* If the code negates only iff positive then make sure to not |
| introduce undefined behavior when negating or computing the absolute. |
| ??? We could use range info if present to check for arg1 == INT_MIN. */ |
| if (negate |
| && (ANY_INTEGRAL_TYPE_P (TREE_TYPE (arg1)) |
| && ! TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))) |
| return false; |
| |
| result = duplicate_ssa_name (result, NULL); |
| |
| if (negate) |
| lhs = make_ssa_name (TREE_TYPE (result)); |
| else |
| lhs = result; |
| |
| /* Build the modify expression with abs expression. */ |
| new_stmt = gimple_build_assign (lhs, ABS_EXPR, rhs); |
| |
| gsi = gsi_last_bb (cond_bb); |
| gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); |
| |
| if (negate) |
| { |
| /* Get the right GSI. We want to insert after the recently |
| added ABS_EXPR statement (which we know is the first statement |
| in the block. */ |
| new_stmt = gimple_build_assign (result, NEGATE_EXPR, lhs); |
| |
| gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT); |
| } |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| |
| /* Optimize x < 0 ? ~y : y into (x >> (prec-1)) ^ y. */ |
| |
| static bool |
| xor_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e0 ATTRIBUTE_UNUSED, edge e1, |
| gimple *phi, tree arg0, tree arg1) |
| { |
| if (!INTEGRAL_TYPE_P (TREE_TYPE (arg1))) |
| return false; |
| |
| /* OTHER_BLOCK must have only one executable statement which must have the |
| form arg0 = ~arg1 or arg1 = ~arg0. */ |
| |
| gimple *assign = last_and_only_stmt (middle_bb); |
| /* If we did not find the proper one's complement assignment, then we cannot |
| optimize. */ |
| if (assign == NULL) |
| return false; |
| |
| /* If we got here, then we have found the only executable statement |
| in OTHER_BLOCK. If it is anything other than arg = ~arg1 or |
| arg1 = ~arg0, then we cannot optimize. */ |
| if (!is_gimple_assign (assign)) |
| return false; |
| |
| if (gimple_assign_rhs_code (assign) != BIT_NOT_EXPR) |
| return false; |
| |
| tree lhs = gimple_assign_lhs (assign); |
| tree rhs = gimple_assign_rhs1 (assign); |
| |
| /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ |
| if (!(lhs == arg0 && rhs == arg1) && !(lhs == arg1 && rhs == arg0)) |
| return false; |
| |
| gimple *cond = last_stmt (cond_bb); |
| tree result = PHI_RESULT (phi); |
| |
| /* Only relationals comparing arg[01] against zero are interesting. */ |
| enum tree_code cond_code = gimple_cond_code (cond); |
| if (cond_code != LT_EXPR && cond_code != GE_EXPR) |
| return false; |
| |
| /* Make sure the conditional is x OP 0. */ |
| tree clhs = gimple_cond_lhs (cond); |
| if (TREE_CODE (clhs) != SSA_NAME |
| || !INTEGRAL_TYPE_P (TREE_TYPE (clhs)) |
| || TYPE_UNSIGNED (TREE_TYPE (clhs)) |
| || TYPE_PRECISION (TREE_TYPE (clhs)) != TYPE_PRECISION (TREE_TYPE (arg1)) |
| || !integer_zerop (gimple_cond_rhs (cond))) |
| return false; |
| |
| /* We need to know which is the true edge and which is the false |
| edge so that we know if have xor or inverted xor. */ |
| edge true_edge, false_edge; |
| extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
| |
| /* For GE_EXPR, if the true edge goes to OTHER_BLOCK, then we |
| will need to invert the result. Similarly for LT_EXPR if |
| the false edge goes to OTHER_BLOCK. */ |
| edge e; |
| if (cond_code == GE_EXPR) |
| e = true_edge; |
| else |
| e = false_edge; |
| |
| bool invert = e->dest == middle_bb; |
| |
| result = duplicate_ssa_name (result, NULL); |
| |
| gimple_stmt_iterator gsi = gsi_last_bb (cond_bb); |
| |
| int prec = TYPE_PRECISION (TREE_TYPE (clhs)); |
| gimple *new_stmt |
| = gimple_build_assign (make_ssa_name (TREE_TYPE (clhs)), RSHIFT_EXPR, clhs, |
| build_int_cst (integer_type_node, prec - 1)); |
| gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT); |
| |
| if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (clhs))) |
| { |
| new_stmt = gimple_build_assign (make_ssa_name (TREE_TYPE (result)), |
| NOP_EXPR, gimple_assign_lhs (new_stmt)); |
| gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT); |
| } |
| lhs = gimple_assign_lhs (new_stmt); |
| |
| if (invert) |
| { |
| new_stmt = gimple_build_assign (make_ssa_name (TREE_TYPE (result)), |
| BIT_NOT_EXPR, rhs); |
| gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT); |
| rhs = gimple_assign_lhs (new_stmt); |
| } |
| |
| new_stmt = gimple_build_assign (result, BIT_XOR_EXPR, lhs, rhs); |
| gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| |
| /* Auxiliary functions to determine the set of memory accesses which |
| can't trap because they are preceded by accesses to the same memory |
| portion. We do that for MEM_REFs, so we only need to track |
| the SSA_NAME of the pointer indirectly referenced. The algorithm |
| simply is a walk over all instructions in dominator order. When |
| we see an MEM_REF we determine if we've already seen a same |
| ref anywhere up to the root of the dominator tree. If we do the |
| current access can't trap. If we don't see any dominating access |
| the current access might trap, but might also make later accesses |
| non-trapping, so we remember it. We need to be careful with loads |
| or stores, for instance a load might not trap, while a store would, |
| so if we see a dominating read access this doesn't mean that a later |
| write access would not trap. Hence we also need to differentiate the |
| type of access(es) seen. |
| |
| ??? We currently are very conservative and assume that a load might |
| trap even if a store doesn't (write-only memory). This probably is |
| overly conservative. |
| |
| We currently support a special case that for !TREE_ADDRESSABLE automatic |
| variables, it could ignore whether something is a load or store because the |
| local stack should be always writable. */ |
| |
| /* A hash-table of references (MEM_REF/ARRAY_REF/COMPONENT_REF), and in which |
| basic block an *_REF through it was seen, which would constitute a |
| no-trap region for same accesses. |
| |
| Size is needed to support 2 MEM_REFs of different types, like |
| MEM<double>(s_1) and MEM<long>(s_1), which would compare equal with |
| OEP_ADDRESS_OF. */ |
| struct ref_to_bb |
| { |
| tree exp; |
| HOST_WIDE_INT size; |
| unsigned int phase; |
| basic_block bb; |
| }; |
| |
| /* Hashtable helpers. */ |
| |
| struct refs_hasher : free_ptr_hash<ref_to_bb> |
| { |
| static inline hashval_t hash (const ref_to_bb *); |
| static inline bool equal (const ref_to_bb *, const ref_to_bb *); |
| }; |
| |
| /* Used for quick clearing of the hash-table when we see calls. |
| Hash entries with phase < nt_call_phase are invalid. */ |
| static unsigned int nt_call_phase; |
| |
| /* The hash function. */ |
| |
| inline hashval_t |
| refs_hasher::hash (const ref_to_bb *n) |
| { |
| inchash::hash hstate; |
| inchash::add_expr (n->exp, hstate, OEP_ADDRESS_OF); |
| hstate.add_hwi (n->size); |
| return hstate.end (); |
| } |
| |
| /* The equality function of *P1 and *P2. */ |
| |
| inline bool |
| refs_hasher::equal (const ref_to_bb *n1, const ref_to_bb *n2) |
| { |
| return operand_equal_p (n1->exp, n2->exp, OEP_ADDRESS_OF) |
| && n1->size == n2->size; |
| } |
| |
| class nontrapping_dom_walker : public dom_walker |
| { |
| public: |
| nontrapping_dom_walker (cdi_direction direction, hash_set<tree> *ps) |
| : dom_walker (direction), m_nontrapping (ps), m_seen_refs (128) |
| {} |
| |
| virtual edge before_dom_children (basic_block); |
| virtual void after_dom_children (basic_block); |
| |
| private: |
| |
| /* We see the expression EXP in basic block BB. If it's an interesting |
| expression (an MEM_REF through an SSA_NAME) possibly insert the |
| expression into the set NONTRAP or the hash table of seen expressions. |
| STORE is true if this expression is on the LHS, otherwise it's on |
| the RHS. */ |
| void add_or_mark_expr (basic_block, tree, bool); |
| |
| hash_set<tree> *m_nontrapping; |
| |
| /* The hash table for remembering what we've seen. */ |
| hash_table<refs_hasher> m_seen_refs; |
| }; |
| |
| /* Called by walk_dominator_tree, when entering the block BB. */ |
| edge |
| nontrapping_dom_walker::before_dom_children (basic_block bb) |
| { |
| edge e; |
| edge_iterator ei; |
| gimple_stmt_iterator gsi; |
| |
| /* If we haven't seen all our predecessors, clear the hash-table. */ |
| FOR_EACH_EDGE (e, ei, bb->preds) |
| if ((((size_t)e->src->aux) & 2) == 0) |
| { |
| nt_call_phase++; |
| break; |
| } |
| |
| /* Mark this BB as being on the path to dominator root and as visited. */ |
| bb->aux = (void*)(1 | 2); |
| |
| /* And walk the statements in order. */ |
| for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gimple *stmt = gsi_stmt (gsi); |
| |
| if ((gimple_code (stmt) == GIMPLE_ASM && gimple_vdef (stmt)) |
| || (is_gimple_call (stmt) |
| && (!nonfreeing_call_p (stmt) || !nonbarrier_call_p (stmt)))) |
| nt_call_phase++; |
| else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt)) |
| { |
| add_or_mark_expr (bb, gimple_assign_lhs (stmt), true); |
| add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), false); |
| } |
| } |
| return NULL; |
| } |
| |
| /* Called by walk_dominator_tree, when basic block BB is exited. */ |
| void |
| nontrapping_dom_walker::after_dom_children (basic_block bb) |
| { |
| /* This BB isn't on the path to dominator root anymore. */ |
| bb->aux = (void*)2; |
| } |
| |
| /* We see the expression EXP in basic block BB. If it's an interesting |
| expression of: |
| 1) MEM_REF |
| 2) ARRAY_REF |
| 3) COMPONENT_REF |
| possibly insert the expression into the set NONTRAP or the hash table |
| of seen expressions. STORE is true if this expression is on the LHS, |
| otherwise it's on the RHS. */ |
| void |
| nontrapping_dom_walker::add_or_mark_expr (basic_block bb, tree exp, bool store) |
| { |
| HOST_WIDE_INT size; |
| |
| if ((TREE_CODE (exp) == MEM_REF || TREE_CODE (exp) == ARRAY_REF |
| || TREE_CODE (exp) == COMPONENT_REF) |
| && (size = int_size_in_bytes (TREE_TYPE (exp))) > 0) |
| { |
| struct ref_to_bb map; |
| ref_to_bb **slot; |
| struct ref_to_bb *r2bb; |
| basic_block found_bb = 0; |
| |
| if (!store) |
| { |
| tree base = get_base_address (exp); |
| /* Only record a LOAD of a local variable without address-taken, as |
| the local stack is always writable. This allows cselim on a STORE |
| with a dominating LOAD. */ |
| if (!auto_var_p (base) || TREE_ADDRESSABLE (base)) |
| return; |
| } |
| |
| /* Try to find the last seen *_REF, which can trap. */ |
| map.exp = exp; |
| map.size = size; |
| slot = m_seen_refs.find_slot (&map, INSERT); |
| r2bb = *slot; |
| if (r2bb && r2bb->phase >= nt_call_phase) |
| found_bb = r2bb->bb; |
| |
| /* If we've found a trapping *_REF, _and_ it dominates EXP |
| (it's in a basic block on the path from us to the dominator root) |
| then we can't trap. */ |
| if (found_bb && (((size_t)found_bb->aux) & 1) == 1) |
| { |
| m_nontrapping->add (exp); |
| } |
| else |
| { |
| /* EXP might trap, so insert it into the hash table. */ |
| if (r2bb) |
| { |
| r2bb->phase = nt_call_phase; |
| r2bb->bb = bb; |
| } |
| else |
| { |
| r2bb = XNEW (struct ref_to_bb); |
| r2bb->phase = nt_call_phase; |
| r2bb->bb = bb; |
| r2bb->exp = exp; |
| r2bb->size = size; |
| *slot = r2bb; |
| } |
| } |
| } |
| } |
| |
| /* This is the entry point of gathering non trapping memory accesses. |
| It will do a dominator walk over the whole function, and it will |
| make use of the bb->aux pointers. It returns a set of trees |
| (the MEM_REFs itself) which can't trap. */ |
| static hash_set<tree> * |
| get_non_trapping (void) |
| { |
| nt_call_phase = 0; |
| hash_set<tree> *nontrap = new hash_set<tree>; |
| |
| nontrapping_dom_walker (CDI_DOMINATORS, nontrap) |
| .walk (cfun->cfg->x_entry_block_ptr); |
| |
| clear_aux_for_blocks (); |
| return nontrap; |
| } |
| |
| /* Do the main work of conditional store replacement. We already know |
| that the recognized pattern looks like so: |
| |
| split: |
| if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1) |
| MIDDLE_BB: |
| something |
| fallthrough (edge E0) |
| JOIN_BB: |
| some more |
| |
| We check that MIDDLE_BB contains only one store, that that store |
| doesn't trap (not via NOTRAP, but via checking if an access to the same |
| memory location dominates us, or the store is to a local addressable |
| object) and that the store has a "simple" RHS. */ |
| |
| static bool |
| cond_store_replacement (basic_block middle_bb, basic_block join_bb, |
| edge e0, edge e1, hash_set<tree> *nontrap) |
| { |
| gimple *assign = last_and_only_stmt (middle_bb); |
| tree lhs, rhs, name, name2; |
| gphi *newphi; |
| gassign *new_stmt; |
| gimple_stmt_iterator gsi; |
| location_t locus; |
| |
| /* Check if middle_bb contains of only one store. */ |
| if (!assign |
| || !gimple_assign_single_p (assign) |
| || gimple_has_volatile_ops (assign)) |
| return false; |
| |
| /* And no PHI nodes so all uses in the single stmt are also |
| available where we insert to. */ |
| if (!gimple_seq_empty_p (phi_nodes (middle_bb))) |
| return false; |
| |
| locus = gimple_location (assign); |
| lhs = gimple_assign_lhs (assign); |
| rhs = gimple_assign_rhs1 (assign); |
| if ((TREE_CODE (lhs) != MEM_REF |
| && TREE_CODE (lhs) != ARRAY_REF |
| && TREE_CODE (lhs) != COMPONENT_REF) |
| || !is_gimple_reg_type (TREE_TYPE (lhs))) |
| return false; |
| |
| /* Prove that we can move the store down. We could also check |
| TREE_THIS_NOTRAP here, but in that case we also could move stores, |
| whose value is not available readily, which we want to avoid. */ |
| if (!nontrap->contains (lhs)) |
| { |
| /* If LHS is an access to a local variable without address-taken |
| (or when we allow data races) and known not to trap, we could |
| always safely move down the store. */ |
| tree base = get_base_address (lhs); |
| if (!auto_var_p (base) |
| || (TREE_ADDRESSABLE (base) && !flag_store_data_races) |
| || tree_could_trap_p (lhs)) |
| return false; |
| } |
| |
| /* Now we've checked the constraints, so do the transformation: |
| 1) Remove the single store. */ |
| gsi = gsi_for_stmt (assign); |
| unlink_stmt_vdef (assign); |
| gsi_remove (&gsi, true); |
| release_defs (assign); |
| |
| /* Make both store and load use alias-set zero as we have to |
| deal with the case of the store being a conditional change |
| of the dynamic type. */ |
| lhs = unshare_expr (lhs); |
| tree *basep = &lhs; |
| while (handled_component_p (*basep)) |
| basep = &TREE_OPERAND (*basep, 0); |
| if (TREE_CODE (*basep) == MEM_REF |
| || TREE_CODE (*basep) == TARGET_MEM_REF) |
| TREE_OPERAND (*basep, 1) |
| = fold_convert (ptr_type_node, TREE_OPERAND (*basep, 1)); |
| else |
| *basep = build2 (MEM_REF, TREE_TYPE (*basep), |
| build_fold_addr_expr (*basep), |
| build_zero_cst (ptr_type_node)); |
| |
| /* 2) Insert a load from the memory of the store to the temporary |
| on the edge which did not contain the store. */ |
| name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore"); |
| new_stmt = gimple_build_assign (name, lhs); |
| gimple_set_location (new_stmt, locus); |
| lhs = unshare_expr (lhs); |
| /* Set TREE_NO_WARNING on the rhs of the load to avoid uninit |
| warnings. */ |
| TREE_NO_WARNING (gimple_assign_rhs1 (new_stmt)) = 1; |
| gsi_insert_on_edge (e1, new_stmt); |
| |
| /* 3) Create a PHI node at the join block, with one argument |
| holding the old RHS, and the other holding the temporary |
| where we stored the old memory contents. */ |
| name2 = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore"); |
| newphi = create_phi_node (name2, join_bb); |
| add_phi_arg (newphi, rhs, e0, locus); |
| add_phi_arg (newphi, name, e1, locus); |
| |
| new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi)); |
| |
| /* 4) Insert that PHI node. */ |
| gsi = gsi_after_labels (join_bb); |
| if (gsi_end_p (gsi)) |
| { |
| gsi = gsi_last_bb (join_bb); |
| gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT); |
| } |
| else |
| gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "\nConditional store replacement happened!"); |
| fprintf (dump_file, "\nReplaced the store with a load."); |
| fprintf (dump_file, "\nInserted a new PHI statement in joint block:\n"); |
| print_gimple_stmt (dump_file, new_stmt, 0, TDF_VOPS|TDF_MEMSYMS); |
| } |
| |
| return true; |
| } |
| |
| /* Do the main work of conditional store replacement. */ |
| |
| static bool |
| cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb, |
| basic_block join_bb, gimple *then_assign, |
| gimple *else_assign) |
| { |
| tree lhs_base, lhs, then_rhs, else_rhs, name; |
| location_t then_locus, else_locus; |
| gimple_stmt_iterator gsi; |
| gphi *newphi; |
| gassign *new_stmt; |
| |
| if (then_assign == NULL |
| || !gimple_assign_single_p (then_assign) |
| || gimple_clobber_p (then_assign) |
| || gimple_has_volatile_ops (then_assign) |
| || else_assign == NULL |
| || !gimple_assign_single_p (else_assign) |
| || gimple_clobber_p (else_assign) |
| || gimple_has_volatile_ops (else_assign)) |
| return false; |
| |
| lhs = gimple_assign_lhs (then_assign); |
| if (!is_gimple_reg_type (TREE_TYPE (lhs)) |
| || !operand_equal_p (lhs, gimple_assign_lhs (else_assign), 0)) |
| return false; |
| |
| lhs_base = get_base_address (lhs); |
| if (lhs_base == NULL_TREE |
| || (!DECL_P (lhs_base) && TREE_CODE (lhs_base) != MEM_REF)) |
| return false; |
| |
| then_rhs = gimple_assign_rhs1 (then_assign); |
| else_rhs = gimple_assign_rhs1 (else_assign); |
| then_locus = gimple_location (then_assign); |
| else_locus = gimple_location (else_assign); |
| |
| /* Now we've checked the constraints, so do the transformation: |
| 1) Remove the stores. */ |
| gsi = gsi_for_stmt (then_assign); |
| unlink_stmt_vdef (then_assign); |
| gsi_remove (&gsi, true); |
| release_defs (then_assign); |
| |
| gsi = gsi_for_stmt (else_assign); |
| unlink_stmt_vdef (else_assign); |
| gsi_remove (&gsi, true); |
| release_defs (else_assign); |
| |
| /* 2) Create a PHI node at the join block, with one argument |
| holding the old RHS, and the other holding the temporary |
| where we stored the old memory contents. */ |
| name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore"); |
| newphi = create_phi_node (name, join_bb); |
| add_phi_arg (newphi, then_rhs, EDGE_SUCC (then_bb, 0), then_locus); |
| add_phi_arg (newphi, else_rhs, EDGE_SUCC (else_bb, 0), else_locus); |
| |
| new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi)); |
| |
| /* 3) Insert that PHI node. */ |
| gsi = gsi_after_labels (join_bb); |
| if (gsi_end_p (gsi)) |
| { |
| gsi = gsi_last_bb (join_bb); |
| gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT); |
| } |
| else |
| gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); |
| |
| return true; |
| } |
| |
| /* Return the single store in BB with VDEF or NULL if there are |
| other stores in the BB or loads following the store. */ |
| |
| static gimple * |
| single_trailing_store_in_bb (basic_block bb, tree vdef) |
| { |
| if (SSA_NAME_IS_DEFAULT_DEF (vdef)) |
| return NULL; |
| gimple *store = SSA_NAME_DEF_STMT (vdef); |
| if (gimple_bb (store) != bb |
| || gimple_code (store) == GIMPLE_PHI) |
| return NULL; |
| |
| /* Verify there is no other store in this BB. */ |
| if (!SSA_NAME_IS_DEFAULT_DEF (gimple_vuse (store)) |
| && gimple_bb (SSA_NAME_DEF_STMT (gimple_vuse (store))) == bb |
| && gimple_code (SSA_NAME_DEF_STMT (gimple_vuse (store))) != GIMPLE_PHI) |
| return NULL; |
| |
| /* Verify there is no load or store after the store. */ |
| use_operand_p use_p; |
| imm_use_iterator imm_iter; |
| FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_vdef (store)) |
| if (USE_STMT (use_p) != store |
| && gimple_bb (USE_STMT (use_p)) == bb) |
| return NULL; |
| |
| return store; |
| } |
| |
| /* Conditional store replacement. We already know |
| that the recognized pattern looks like so: |
| |
| split: |
| if (cond) goto THEN_BB; else goto ELSE_BB (edge E1) |
| THEN_BB: |
| ... |
| X = Y; |
| ... |
| goto JOIN_BB; |
| ELSE_BB: |
| ... |
| X = Z; |
| ... |
| fallthrough (edge E0) |
| JOIN_BB: |
| some more |
| |
| We check that it is safe to sink the store to JOIN_BB by verifying that |
| there are no read-after-write or write-after-write dependencies in |
| THEN_BB and ELSE_BB. */ |
| |
| static bool |
| cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb, |
| basic_block join_bb) |
| { |
| vec<data_reference_p> then_datarefs, else_datarefs; |
| vec<ddr_p> then_ddrs, else_ddrs; |
| gimple *then_store, *else_store; |
| bool found, ok = false, res; |
| struct data_dependence_relation *ddr; |
| data_reference_p then_dr, else_dr; |
| int i, j; |
| tree then_lhs, else_lhs; |
| basic_block blocks[3]; |
| |
| /* Handle the case with single store in THEN_BB and ELSE_BB. That is |
| cheap enough to always handle as it allows us to elide dependence |
| checking. */ |
| gphi *vphi = NULL; |
| for (gphi_iterator si = gsi_start_phis (join_bb); !gsi_end_p (si); |
| gsi_next (&si)) |
| if (virtual_operand_p (gimple_phi_result (si.phi ()))) |
| { |
| vphi = si.phi (); |
| break; |
| } |
| if (!vphi) |
| return false; |
| tree then_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (then_bb)); |
| tree else_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (else_bb)); |
| gimple *then_assign = single_trailing_store_in_bb (then_bb, then_vdef); |
| if (then_assign) |
| { |
| gimple *else_assign = single_trailing_store_in_bb (else_bb, else_vdef); |
| if (else_assign) |
| return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb, |
| then_assign, else_assign); |
| } |
| |
| /* If either vectorization or if-conversion is disabled then do |
| not sink any stores. */ |
| if (param_max_stores_to_sink == 0 |
| || (!flag_tree_loop_vectorize && !flag_tree_slp_vectorize) |
| || !flag_tree_loop_if_convert) |
| return false; |
| |
| /* Find data references. */ |
| then_datarefs.create (1); |
| else_datarefs.create (1); |
| if ((find_data_references_in_bb (NULL, then_bb, &then_datarefs) |
| == chrec_dont_know) |
| || !then_datarefs.length () |
| || (find_data_references_in_bb (NULL, else_bb, &else_datarefs) |
| == chrec_dont_know) |
| || !else_datarefs.length ()) |
| { |
| free_data_refs (then_datarefs); |
| free_data_refs (else_datarefs); |
| return false; |
| } |
| |
| /* Find pairs of stores with equal LHS. */ |
| auto_vec<gimple *, 1> then_stores, else_stores; |
| FOR_EACH_VEC_ELT (then_datarefs, i, then_dr) |
| { |
| if (DR_IS_READ (then_dr)) |
| continue; |
| |
| then_store = DR_STMT (then_dr); |
| then_lhs = gimple_get_lhs (then_store); |
| if (then_lhs == NULL_TREE) |
| continue; |
| found = false; |
| |
| FOR_EACH_VEC_ELT (else_datarefs, j, else_dr) |
| { |
| if (DR_IS_READ (else_dr)) |
| continue; |
| |
| else_store = DR_STMT (else_dr); |
| else_lhs = gimple_get_lhs (else_store); |
| if (else_lhs == NULL_TREE) |
| continue; |
| |
| if (operand_equal_p (then_lhs, else_lhs, 0)) |
| { |
| found = true; |
| break; |
| } |
| } |
| |
| if (!found) |
| continue; |
| |
| then_stores.safe_push (then_store); |
| else_stores.safe_push (else_store); |
| } |
| |
| /* No pairs of stores found. */ |
| if (!then_stores.length () |
| || then_stores.length () > (unsigned) param_max_stores_to_sink) |
| { |
| free_data_refs (then_datarefs); |
| free_data_refs (else_datarefs); |
| return false; |
| } |
| |
| /* Compute and check data dependencies in both basic blocks. */ |
| then_ddrs.create (1); |
| else_ddrs.create (1); |
| if (!compute_all_dependences (then_datarefs, &then_ddrs, |
| vNULL, false) |
| || !compute_all_dependences (else_datarefs, &else_ddrs, |
| vNULL, false)) |
| { |
| free_dependence_relations (then_ddrs); |
| free_dependence_relations (else_ddrs); |
| free_data_refs (then_datarefs); |
| free_data_refs (else_datarefs); |
| return false; |
| } |
| blocks[0] = then_bb; |
| blocks[1] = else_bb; |
| blocks[2] = join_bb; |
| renumber_gimple_stmt_uids_in_blocks (blocks, 3); |
| |
| /* Check that there are no read-after-write or write-after-write dependencies |
| in THEN_BB. */ |
| FOR_EACH_VEC_ELT (then_ddrs, i, ddr) |
| { |
| struct data_reference *dra = DDR_A (ddr); |
| struct data_reference *drb = DDR_B (ddr); |
| |
| if (DDR_ARE_DEPENDENT (ddr) != chrec_known |
| && ((DR_IS_READ (dra) && DR_IS_WRITE (drb) |
| && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb))) |
| || (DR_IS_READ (drb) && DR_IS_WRITE (dra) |
| && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra))) |
| || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb)))) |
| { |
| free_dependence_relations (then_ddrs); |
| free_dependence_relations (else_ddrs); |
| free_data_refs (then_datarefs); |
| free_data_refs (else_datarefs); |
| return false; |
| } |
| } |
| |
| /* Check that there are no read-after-write or write-after-write dependencies |
| in ELSE_BB. */ |
| FOR_EACH_VEC_ELT (else_ddrs, i, ddr) |
| { |
| struct data_reference *dra = DDR_A (ddr); |
| struct data_reference *drb = DDR_B (ddr); |
| |
| if (DDR_ARE_DEPENDENT (ddr) != chrec_known |
| && ((DR_IS_READ (dra) && DR_IS_WRITE (drb) |
| && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb))) |
| || (DR_IS_READ (drb) && DR_IS_WRITE (dra) |
| && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra))) |
| || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb)))) |
| { |
| free_dependence_relations (then_ddrs); |
| free_dependence_relations (else_ddrs); |
| free_data_refs (then_datarefs); |
| free_data_refs (else_datarefs); |
| return false; |
| } |
| } |
| |
| /* Sink stores with same LHS. */ |
| FOR_EACH_VEC_ELT (then_stores, i, then_store) |
| { |
| else_store = else_stores[i]; |
| res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb, |
| then_store, else_store); |
| ok = ok || res; |
| } |
| |
| free_dependence_relations (then_ddrs); |
| free_dependence_relations (else_ddrs); |
| free_data_refs (then_datarefs); |
| free_data_refs (else_datarefs); |
| |
| return ok; |
| } |
| |
| /* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB. */ |
| |
| static bool |
| local_mem_dependence (gimple *stmt, basic_block bb) |
| { |
| tree vuse = gimple_vuse (stmt); |
| gimple *def; |
| |
| if (!vuse) |
| return false; |
| |
| def = SSA_NAME_DEF_STMT (vuse); |
| return (def && gimple_bb (def) == bb); |
| } |
| |
| /* Given a "diamond" control-flow pattern where BB0 tests a condition, |
| BB1 and BB2 are "then" and "else" blocks dependent on this test, |
| and BB3 rejoins control flow following BB1 and BB2, look for |
| opportunities to hoist loads as follows. If BB3 contains a PHI of |
| two loads, one each occurring in BB1 and BB2, and the loads are |
| provably of adjacent fields in the same structure, then move both |
| loads into BB0. Of course this can only be done if there are no |
| dependencies preventing such motion. |
| |
| One of the hoisted loads will always be speculative, so the |
| transformation is currently conservative: |
| |
| - The fields must be strictly adjacent. |
| - The two fields must occupy a single memory block that is |
| guaranteed to not cross a page boundary. |
| |
| The last is difficult to prove, as such memory blocks should be |
| aligned on the minimum of the stack alignment boundary and the |
| alignment guaranteed by heap allocation interfaces. Thus we rely |
| on a parameter for the alignment value. |
| |
| Provided a good value is used for the last case, the first |
| restriction could possibly be relaxed. */ |
| |
| static void |
| hoist_adjacent_loads (basic_block bb0, basic_block bb1, |
| basic_block bb2, basic_block bb3) |
| { |
| int param_align = param_l1_cache_line_size; |
| unsigned param_align_bits = (unsigned) (param_align * BITS_PER_UNIT); |
| gphi_iterator gsi; |
| |
| /* Walk the phis in bb3 looking for an opportunity. We are looking |
| for phis of two SSA names, one each of which is defined in bb1 and |
| bb2. */ |
| for (gsi = gsi_start_phis (bb3); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi_stmt = gsi.phi (); |
| gimple *def1, *def2; |
| tree arg1, arg2, ref1, ref2, field1, field2; |
| tree tree_offset1, tree_offset2, tree_size2, next; |
| int offset1, offset2, size2; |
| unsigned align1; |
| gimple_stmt_iterator gsi2; |
| basic_block bb_for_def1, bb_for_def2; |
| |
| if (gimple_phi_num_args (phi_stmt) != 2 |
| || virtual_operand_p (gimple_phi_result (phi_stmt))) |
| continue; |
| |
| arg1 = gimple_phi_arg_def (phi_stmt, 0); |
| arg2 = gimple_phi_arg_def (phi_stmt, 1); |
| |
| if (TREE_CODE (arg1) != SSA_NAME |
| || TREE_CODE (arg2) != SSA_NAME |
| || SSA_NAME_IS_DEFAULT_DEF (arg1) |
| || SSA_NAME_IS_DEFAULT_DEF (arg2)) |
| continue; |
| |
| def1 = SSA_NAME_DEF_STMT (arg1); |
| def2 = SSA_NAME_DEF_STMT (arg2); |
| |
| if ((gimple_bb (def1) != bb1 || gimple_bb (def2) != bb2) |
| && (gimple_bb (def2) != bb1 || gimple_bb (def1) != bb2)) |
| continue; |
| |
| /* Check the mode of the arguments to be sure a conditional move |
| can be generated for it. */ |
| if (optab_handler (movcc_optab, TYPE_MODE (TREE_TYPE (arg1))) |
| == CODE_FOR_nothing) |
| continue; |
| |
| /* Both statements must be assignments whose RHS is a COMPONENT_REF. */ |
| if (!gimple_assign_single_p (def1) |
| || !gimple_assign_single_p (def2) |
| || gimple_has_volatile_ops (def1) |
| || gimple_has_volatile_ops (def2)) |
| continue; |
| |
| ref1 = gimple_assign_rhs1 (def1); |
| ref2 = gimple_assign_rhs1 (def2); |
| |
| if (TREE_CODE (ref1) != COMPONENT_REF |
| || TREE_CODE (ref2) != COMPONENT_REF) |
| continue; |
| |
| /* The zeroth operand of the two component references must be |
| identical. It is not sufficient to compare get_base_address of |
| the two references, because this could allow for different |
| elements of the same array in the two trees. It is not safe to |
| assume that the existence of one array element implies the |
| existence of a different one. */ |
| if (!operand_equal_p (TREE_OPERAND (ref1, 0), TREE_OPERAND (ref2, 0), 0)) |
| continue; |
| |
| field1 = TREE_OPERAND (ref1, 1); |
| field2 = TREE_OPERAND (ref2, 1); |
| |
| /* Check for field adjacency, and ensure field1 comes first. */ |
| for (next = DECL_CHAIN (field1); |
| next && TREE_CODE (next) != FIELD_DECL; |
| next = DECL_CHAIN (next)) |
| ; |
| |
| if (next != field2) |
| { |
| for (next = DECL_CHAIN (field2); |
| next && TREE_CODE (next) != FIELD_DECL; |
| next = DECL_CHAIN (next)) |
| ; |
| |
| if (next != field1) |
| continue; |
| |
| std::swap (field1, field2); |
| std::swap (def1, def2); |
| } |
| |
| bb_for_def1 = gimple_bb (def1); |
| bb_for_def2 = gimple_bb (def2); |
| |
| /* Check for proper alignment of the first field. */ |
| tree_offset1 = bit_position (field1); |
| tree_offset2 = bit_position (field2); |
| tree_size2 = DECL_SIZE (field2); |
| |
| if (!tree_fits_uhwi_p (tree_offset1) |
| || !tree_fits_uhwi_p (tree_offset2) |
| || !tree_fits_uhwi_p (tree_size2)) |
| continue; |
| |
| offset1 = tree_to_uhwi (tree_offset1); |
| offset2 = tree_to_uhwi (tree_offset2); |
| size2 = tree_to_uhwi (tree_size2); |
| align1 = DECL_ALIGN (field1) % param_align_bits; |
| |
| if (offset1 % BITS_PER_UNIT != 0) |
| continue; |
| |
| /* For profitability, the two field references should fit within |
| a single cache line. */ |
| if (align1 + offset2 - offset1 + size2 > param_align_bits) |
| continue; |
| |
| /* The two expressions cannot be dependent upon vdefs defined |
| in bb1/bb2. */ |
| if (local_mem_dependence (def1, bb_for_def1) |
| || local_mem_dependence (def2, bb_for_def2)) |
| continue; |
| |
| /* The conditions are satisfied; hoist the loads from bb1 and bb2 into |
| bb0. We hoist the first one first so that a cache miss is handled |
| efficiently regardless of hardware cache-fill policy. */ |
| gsi2 = gsi_for_stmt (def1); |
| gsi_move_to_bb_end (&gsi2, bb0); |
| gsi2 = gsi_for_stmt (def2); |
| gsi_move_to_bb_end (&gsi2, bb0); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, |
| "\nHoisting adjacent loads from %d and %d into %d: \n", |
| bb_for_def1->index, bb_for_def2->index, bb0->index); |
| print_gimple_stmt (dump_file, def1, 0, TDF_VOPS|TDF_MEMSYMS); |
| print_gimple_stmt (dump_file, def2, 0, TDF_VOPS|TDF_MEMSYMS); |
| } |
| } |
| } |
| |
| /* Determine whether we should attempt to hoist adjacent loads out of |
| diamond patterns in pass_phiopt. Always hoist loads if |
| -fhoist-adjacent-loads is specified and the target machine has |
| both a conditional move instruction and a defined cache line size. */ |
| |
| static bool |
| gate_hoist_loads (void) |
| { |
| return (flag_hoist_adjacent_loads == 1 |
| && param_l1_cache_line_size |
| && HAVE_conditional_move); |
| } |
| |
| /* This pass tries to replaces an if-then-else block with an |
| assignment. We have four kinds of transformations. Some of these |
| transformations are also performed by the ifcvt RTL optimizer. |
| |
| Conditional Replacement |
| ----------------------- |
| |
| This transformation, implemented in conditional_replacement, |
| replaces |
| |
| bb0: |
| if (cond) goto bb2; else goto bb1; |
| bb1: |
| bb2: |
| x = PHI <0 (bb1), 1 (bb0), ...>; |
| |
| with |
| |
| bb0: |
| x' = cond; |
| goto bb2; |
| bb2: |
| x = PHI <x' (bb0), ...>; |
| |
| We remove bb1 as it becomes unreachable. This occurs often due to |
| gimplification of conditionals. |
| |
| Value Replacement |
| ----------------- |
| |
| This transformation, implemented in value_replacement, replaces |
| |
| bb0: |
| if (a != b) goto bb2; else goto bb1; |
| bb1: |
| bb2: |
| x = PHI <a (bb1), b (bb0), ...>; |
| |
| with |
| |
| bb0: |
| bb2: |
| x = PHI <b (bb0), ...>; |
| |
| This opportunity can sometimes occur as a result of other |
| optimizations. |
| |
| |
| Another case caught by value replacement looks like this: |
| |
| bb0: |
| t1 = a == CONST; |
| t2 = b > c; |
| t3 = t1 & t2; |
| if (t3 != 0) goto bb1; else goto bb2; |
| bb1: |
| bb2: |
| x = PHI (CONST, a) |
| |
| Gets replaced with: |
| bb0: |
| bb2: |
| t1 = a == CONST; |
| t2 = b > c; |
| t3 = t1 & t2; |
| x = a; |
| |
| ABS Replacement |
| --------------- |
| |
| This transformation, implemented in abs_replacement, replaces |
| |
| bb0: |
| if (a >= 0) goto bb2; else goto bb1; |
| bb1: |
| x = -a; |
| bb2: |
| x = PHI <x (bb1), a (bb0), ...>; |
| |
| with |
| |
| bb0: |
| x' = ABS_EXPR< a >; |
| bb2: |
| x = PHI <x' (bb0), ...>; |
| |
| MIN/MAX Replacement |
| ------------------- |
| |
| This transformation, minmax_replacement replaces |
| |
| bb0: |
| if (a <= b) goto bb2; else goto bb1; |
| bb1: |
| bb2: |
| x = PHI <b (bb1), a (bb0), ...>; |
| |
| with |
| |
| bb0: |
| x' = MIN_EXPR (a, b) |
| bb2: |
|