| /* Optimization of PHI nodes by converting them into straightline code. |
| Copyright (C) 2004, 2005 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 2, 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 COPYING. If not, write to the Free |
| Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301, USA. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "tm.h" |
| #include "ggc.h" |
| #include "tree.h" |
| #include "rtl.h" |
| #include "flags.h" |
| #include "tm_p.h" |
| #include "basic-block.h" |
| #include "timevar.h" |
| #include "diagnostic.h" |
| #include "tree-flow.h" |
| #include "tree-pass.h" |
| #include "tree-dump.h" |
| #include "langhooks.h" |
| |
| static unsigned int tree_ssa_phiopt (void); |
| static bool conditional_replacement (basic_block, basic_block, |
| edge, edge, tree, tree, tree); |
| static bool value_replacement (basic_block, basic_block, |
| edge, edge, tree, tree, tree); |
| static bool minmax_replacement (basic_block, basic_block, |
| edge, edge, tree, tree, tree); |
| static bool abs_replacement (basic_block, basic_block, |
| edge, edge, tree, tree, tree); |
| static void replace_phi_edge_with_variable (basic_block, edge, tree, tree); |
| static basic_block *blocks_in_phiopt_order (void); |
| |
| /* 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. |
| |
| 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: |
| x = PHI <x' (bb0), ...>; |
| |
| A similar transformation is done for MAX_EXPR. */ |
| |
| static unsigned int |
| tree_ssa_phiopt (void) |
| { |
| basic_block bb; |
| basic_block *bb_order; |
| unsigned n, i; |
| bool cfgchanged = false; |
| |
| /* 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 = blocks_in_phiopt_order (); |
| n = n_basic_blocks - NUM_FIXED_BLOCKS; |
| |
| for (i = 0; i < n; i++) |
| { |
| tree cond_expr; |
| tree phi; |
| basic_block bb1, bb2; |
| edge e1, e2; |
| tree arg0, arg1; |
| |
| bb = bb_order[i]; |
| |
| cond_expr = last_stmt (bb); |
| /* Check to see if the last statement is a COND_EXPR. */ |
| if (!cond_expr |
| || TREE_CODE (cond_expr) != COND_EXPR) |
| 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) |
| { |
| basic_block bb_tmp = bb1; |
| edge e_tmp = e1; |
| bb1 = bb2; |
| bb2 = bb_tmp; |
| e1 = e2; |
| e2 = e_tmp; |
| } |
| 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; |
| |
| phi = phi_nodes (bb2); |
| |
| /* Check to make sure that there is only one PHI node. |
| TODO: we could do it with more than one iff the other PHI nodes |
| have the same elements for these two edges. */ |
| if (!phi || PHI_CHAIN (phi) != NULL) |
| continue; |
| |
| arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx); |
| arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx); |
| |
| /* Something is wrong if we cannot find the arguments in the PHI |
| node. */ |
| gcc_assert (arg0 != NULL && arg1 != NULL); |
| |
| /* Do the replacement of conditional if it can be done. */ |
| if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
| cfgchanged = true; |
| else if (value_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 (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
| cfgchanged = true; |
| } |
| |
| free (bb_order); |
| |
| /* If the CFG has changed, we should cleanup the CFG. */ |
| return cfgchanged ? TODO_cleanup_cfg : 0; |
| } |
| |
| /* Returns the list of basic blocks in the function in an order that guarantees |
| that if a block X has just a single predecessor Y, then Y is after X in the |
| ordering. */ |
| |
| static basic_block * |
| blocks_in_phiopt_order (void) |
| { |
| basic_block x, y; |
| basic_block *order = XNEWVEC (basic_block, n_basic_blocks); |
| unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS; |
| unsigned np, i; |
| sbitmap visited = sbitmap_alloc (last_basic_block); |
| |
| #define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index)) |
| #define VISITED_P(BB) (TEST_BIT (visited, (BB)->index)) |
| |
| sbitmap_zero (visited); |
| |
| MARK_VISITED (ENTRY_BLOCK_PTR); |
| FOR_EACH_BB (x) |
| { |
| if (VISITED_P (x)) |
| continue; |
| |
| /* Walk the predecessors of x as long as they have precisely one |
| predecessor and add them to the list, so that they get stored |
| after x. */ |
| for (y = x, np = 1; |
| single_pred_p (y) && !VISITED_P (single_pred (y)); |
| y = single_pred (y)) |
| np++; |
| for (y = x, i = n - np; |
| single_pred_p (y) && !VISITED_P (single_pred (y)); |
| y = single_pred (y), i++) |
| { |
| order[i] = y; |
| MARK_VISITED (y); |
| } |
| order[i] = y; |
| MARK_VISITED (y); |
| |
| gcc_assert (i == n - 1); |
| n -= np; |
| } |
| |
| sbitmap_free (visited); |
| gcc_assert (n == 0); |
| return order; |
| |
| #undef MARK_VISITED |
| #undef VISITED_P |
| } |
| |
| /* Return TRUE if block BB has no executable statements, otherwise return |
| FALSE. */ |
| bool |
| empty_block_p (basic_block bb) |
| { |
| block_stmt_iterator bsi; |
| |
| /* BB must have no executable statements. */ |
| bsi = bsi_start (bb); |
| while (!bsi_end_p (bsi) |
| && (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR |
| || IS_EMPTY_STMT (bsi_stmt (bsi)))) |
| bsi_next (&bsi); |
| |
| if (!bsi_end_p (bsi)) |
| return false; |
| |
| return true; |
| } |
| |
| /* 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, tree phi, tree new) |
| { |
| basic_block bb = bb_for_stmt (phi); |
| basic_block block_to_remove; |
| block_stmt_iterator bsi; |
| |
| /* Change the PHI argument to new. */ |
| SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new); |
| |
| /* 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 = REG_BR_PROB_BASE; |
| EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count; |
| |
| 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 = REG_BR_PROB_BASE; |
| EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count; |
| |
| 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. */ |
| bsi = bsi_last (cond_block); |
| bsi_remove (&bsi, 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); |
| } |
| |
| /* 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, tree phi, |
| tree arg0, tree arg1) |
| { |
| tree result; |
| tree old_result = NULL; |
| tree new, cond; |
| block_stmt_iterator bsi; |
| edge true_edge, false_edge; |
| tree new_var = NULL; |
| tree new_var1; |
| |
| /* The PHI arguments have the constants 0 and 1, then convert |
| it to the conditional. */ |
| if ((integer_zerop (arg0) && integer_onep (arg1)) |
| || (integer_zerop (arg1) && integer_onep (arg0))) |
| ; |
| else |
| return false; |
| |
| if (!empty_block_p (middle_bb)) |
| return false; |
| |
| /* If the condition is not a naked SSA_NAME and its type does not |
| match the type of the result, then we have to create a new |
| variable to optimize this case as it would likely create |
| non-gimple code when the condition was converted to the |
| result's type. */ |
| cond = COND_EXPR_COND (last_stmt (cond_bb)); |
| result = PHI_RESULT (phi); |
| if (TREE_CODE (cond) != SSA_NAME |
| && !lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result))) |
| { |
| tree tmp; |
| |
| if (!COMPARISON_CLASS_P (cond)) |
| return false; |
| |
| tmp = create_tmp_var (TREE_TYPE (cond), NULL); |
| add_referenced_var (tmp); |
| new_var = make_ssa_name (tmp, NULL); |
| old_result = cond; |
| cond = new_var; |
| } |
| |
| /* If the condition was a naked SSA_NAME and the type is not the |
| same as the type of the result, then convert the type of the |
| condition. */ |
| if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result))) |
| cond = fold_convert (TREE_TYPE (result), cond); |
| |
| /* 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); |
| |
| /* Insert our new statement at the end of conditional block before the |
| COND_EXPR. */ |
| bsi = bsi_last (cond_bb); |
| bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT); |
| |
| if (old_result) |
| { |
| tree new1; |
| |
| new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result), |
| TREE_OPERAND (old_result, 0), |
| TREE_OPERAND (old_result, 1)); |
| |
| new1 = build2 (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1); |
| SSA_NAME_DEF_STMT (new_var) = new1; |
| |
| bsi_insert_after (&bsi, new1, BSI_NEW_STMT); |
| } |
| |
| new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL); |
| |
| |
| /* 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. |
| |
| There is a single PHI node at the join point (BB) and its arguments |
| are constants (0, 1). |
| |
| So, given the condition COND, and the two PHI arguments, we can |
| rewrite this PHI into non-branching code: |
| |
| dest = (COND) or dest = COND' |
| |
| 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 COND_EXPR |
| will directly reach BB and thus be associated with an argument. */ |
| if ((e0 == true_edge && integer_onep (arg0)) |
| || (e0 == false_edge && integer_zerop (arg0)) |
| || (e1 == true_edge && integer_onep (arg1)) |
| || (e1 == false_edge && integer_zerop (arg1))) |
| { |
| new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond); |
| } |
| else |
| { |
| tree cond1 = invert_truthvalue (cond); |
| |
| cond = cond1; |
| |
| /* If what we get back is a conditional expression, there is no |
| way that it can be gimple. */ |
| if (TREE_CODE (cond) == COND_EXPR) |
| { |
| release_ssa_name (new_var1); |
| return false; |
| } |
| |
| /* If COND is not something we can expect to be reducible to a GIMPLE |
| condition, return early. */ |
| if (is_gimple_cast (cond)) |
| cond1 = TREE_OPERAND (cond, 0); |
| if (TREE_CODE (cond1) == TRUTH_NOT_EXPR |
| && !is_gimple_val (TREE_OPERAND (cond1, 0))) |
| { |
| release_ssa_name (new_var1); |
| return false; |
| } |
| |
| /* If what we get back is not gimple try to create it as gimple by |
| using a temporary variable. */ |
| if (is_gimple_cast (cond) |
| && !is_gimple_val (TREE_OPERAND (cond, 0))) |
| { |
| tree op0, tmp, cond_tmp; |
| |
| /* Only "real" casts are OK here, not everything that is |
| acceptable to is_gimple_cast. Make sure we don't do |
| anything stupid here. */ |
| gcc_assert (TREE_CODE (cond) == NOP_EXPR |
| || TREE_CODE (cond) == CONVERT_EXPR); |
| |
| op0 = TREE_OPERAND (cond, 0); |
| tmp = create_tmp_var (TREE_TYPE (op0), NULL); |
| add_referenced_var (tmp); |
| cond_tmp = make_ssa_name (tmp, NULL); |
| new = build2 (MODIFY_EXPR, TREE_TYPE (cond_tmp), cond_tmp, op0); |
| SSA_NAME_DEF_STMT (cond_tmp) = new; |
| |
| bsi_insert_after (&bsi, new, BSI_NEW_STMT); |
| cond = fold_convert (TREE_TYPE (result), cond_tmp); |
| } |
| |
| new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond); |
| } |
| |
| bsi_insert_after (&bsi, new, BSI_NEW_STMT); |
| |
| SSA_NAME_DEF_STMT (new_var1) = new; |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| |
| /* The function value_replacement does the main work of doing the value |
| 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 |
| value_replacement (basic_block cond_bb, basic_block middle_bb, |
| edge e0, edge e1, tree phi, |
| tree arg0, tree arg1) |
| { |
| tree cond; |
| edge true_edge, false_edge; |
| |
| /* If the type says honor signed zeros we cannot do this |
| optimization. */ |
| if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
| return false; |
| |
| if (!empty_block_p (middle_bb)) |
| return false; |
| |
| cond = COND_EXPR_COND (last_stmt (cond_bb)); |
| |
| /* This transformation is only valid for equality comparisons. */ |
| if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR) |
| 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); |
| |
| /* 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_phi_arg_p (arg0, TREE_OPERAND (cond, 0)) |
| && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1))) |
| || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0)) |
| && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1)))) |
| { |
| 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 = (TREE_CODE (cond) == 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; |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, arg); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| return false; |
| } |
| |
| /* 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, tree phi, |
| tree arg0, tree arg1) |
| { |
| tree result, type; |
| tree cond, new; |
| edge true_edge, false_edge; |
| enum tree_code cmp, minmax, ass_code; |
| tree smaller, larger, arg_true, arg_false; |
| block_stmt_iterator bsi, bsi_from; |
| |
| type = TREE_TYPE (PHI_RESULT (phi)); |
| |
| /* The optimization may be unsafe due to NaNs. */ |
| if (HONOR_NANS (TYPE_MODE (type))) |
| return false; |
| |
| cond = COND_EXPR_COND (last_stmt (cond_bb)); |
| cmp = TREE_CODE (cond); |
| result = PHI_RESULT (phi); |
| |
| /* This transformation is only valid for order comparisons. Record which |
| operand is smaller/larger if the result of the comparison is true. */ |
| if (cmp == LT_EXPR || cmp == LE_EXPR) |
| { |
| smaller = TREE_OPERAND (cond, 0); |
| larger = TREE_OPERAND (cond, 1); |
| } |
| else if (cmp == GT_EXPR || cmp == GE_EXPR) |
| { |
| smaller = TREE_OPERAND (cond, 1); |
| larger = TREE_OPERAND (cond, 0); |
| } |
| 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); |
| |
| /* 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) |
| && operand_equal_for_phi_arg_p (arg_false, larger)) |
| { |
| /* Case |
| |
| if (smaller < larger) |
| rslt = smaller; |
| else |
| rslt = larger; */ |
| minmax = MIN_EXPR; |
| } |
| else if (operand_equal_for_phi_arg_p (arg_false, smaller) |
| && operand_equal_for_phi_arg_p (arg_true, 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); */ |
| |
| tree assign = last_and_only_stmt (middle_bb); |
| tree lhs, rhs, op0, op1, bound; |
| |
| if (!assign |
| || TREE_CODE (assign) != MODIFY_EXPR) |
| return false; |
| |
| lhs = TREE_OPERAND (assign, 0); |
| rhs = TREE_OPERAND (assign, 1); |
| ass_code = TREE_CODE (rhs); |
| if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) |
| return false; |
| op0 = TREE_OPERAND (rhs, 0); |
| op1 = TREE_OPERAND (rhs, 1); |
| |
| 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)) |
| { |
| /* 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)) |
| bound = op1; |
| else if (operand_equal_for_phi_arg_p (op1, 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)) |
| { |
| /* 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)) |
| 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 (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)) |
| { |
| /* 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)) |
| bound = op1; |
| else if (operand_equal_for_phi_arg_p (op1, 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)) |
| { |
| /* 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. */ |
| bsi = bsi_last (cond_bb); |
| bsi_from = bsi_last (middle_bb); |
| bsi_move_before (&bsi_from, &bsi); |
| } |
| |
| /* Emit the statement to compute min/max. */ |
| result = duplicate_ssa_name (PHI_RESULT (phi), NULL); |
| new = build2 (MODIFY_EXPR, type, result, |
| build2 (minmax, type, arg0, arg1)); |
| SSA_NAME_DEF_STMT (result) = new; |
| bsi = bsi_last (cond_bb); |
| bsi_insert_before (&bsi, new, BSI_NEW_STMT); |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
| 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, |
| tree phi, tree arg0, tree arg1) |
| { |
| tree result; |
| tree new, cond; |
| block_stmt_iterator bsi; |
| edge true_edge, false_edge; |
| tree 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 (TYPE_MODE (TREE_TYPE (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 can not |
| 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 can not optimize. */ |
| if (TREE_CODE (assign) != MODIFY_EXPR) |
| return false; |
| |
| lhs = TREE_OPERAND (assign, 0); |
| rhs = TREE_OPERAND (assign, 1); |
| |
| if (TREE_CODE (rhs) != NEGATE_EXPR) |
| return false; |
| |
| rhs = TREE_OPERAND (rhs, 0); |
| |
| /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ |
| if (!(lhs == arg0 && rhs == arg1) |
| && !(lhs == arg1 && rhs == arg0)) |
| return false; |
| |
| cond = COND_EXPR_COND (last_stmt (cond_bb)); |
| result = PHI_RESULT (phi); |
| |
| /* Only relationals comparing arg[01] against zero are interesting. */ |
| cond_code = TREE_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 (TREE_OPERAND (cond, 0) != rhs) |
| return false; |
| |
| if (FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1))) |
| ? real_zerop (TREE_OPERAND (cond, 1)) |
| : integer_zerop (TREE_OPERAND (cond, 1))) |
| ; |
| 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; |
| |
| result = duplicate_ssa_name (result, NULL); |
| |
| if (negate) |
| { |
| tree tmp = create_tmp_var (TREE_TYPE (result), NULL); |
| add_referenced_var (tmp); |
| lhs = make_ssa_name (tmp, NULL); |
| } |
| else |
| lhs = result; |
| |
| /* Build the modify expression with abs expression. */ |
| new = build2 (MODIFY_EXPR, TREE_TYPE (lhs), |
| lhs, build1 (ABS_EXPR, TREE_TYPE (lhs), rhs)); |
| SSA_NAME_DEF_STMT (lhs) = new; |
| |
| bsi = bsi_last (cond_bb); |
| bsi_insert_before (&bsi, new, BSI_NEW_STMT); |
| |
| if (negate) |
| { |
| /* Get the right BSI. We want to insert after the recently |
| added ABS_EXPR statement (which we know is the first statement |
| in the block. */ |
| new = build2 (MODIFY_EXPR, TREE_TYPE (result), |
| result, build1 (NEGATE_EXPR, TREE_TYPE (lhs), lhs)); |
| SSA_NAME_DEF_STMT (result) = new; |
| |
| bsi_insert_after (&bsi, new, BSI_NEW_STMT); |
| } |
| |
| replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
| |
| /* Note that we optimized this PHI. */ |
| return true; |
| } |
| |
| |
| /* Always do these optimizations if we have SSA |
| trees to work on. */ |
| static bool |
| gate_phiopt (void) |
| { |
| return 1; |
| } |
| |
| struct tree_opt_pass pass_phiopt = |
| { |
| "phiopt", /* name */ |
| gate_phiopt, /* gate */ |
| tree_ssa_phiopt, /* execute */ |
| NULL, /* sub */ |
| NULL, /* next */ |
| 0, /* static_pass_number */ |
| TV_TREE_PHIOPT, /* tv_id */ |
| PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_dump_func |
| | TODO_ggc_collect |
| | TODO_verify_ssa |
| | TODO_verify_flow |
| | TODO_verify_stmts, /* todo_flags_finish */ |
| 0 /* letter */ |
| }; |