/* Routines for discovering and unpropagating edge equivalences.
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/* Routines for discovering and unpropagating edge equivalences.
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Copyright (C) 2005, 2007 Free Software Foundation, Inc.
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Copyright (C) 2005, 2007 Free Software Foundation, Inc.
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This file is part of GCC.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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any later version.
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GCC is distributed in the hope that it will be useful,
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#include "config.h"
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#include "system.h"
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#include "system.h"
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#include "coretypes.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "tm.h"
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#include "tree.h"
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#include "tree.h"
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#include "flags.h"
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#include "flags.h"
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#include "rtl.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "tm_p.h"
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#include "ggc.h"
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#include "ggc.h"
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#include "basic-block.h"
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#include "basic-block.h"
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#include "output.h"
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#include "output.h"
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#include "expr.h"
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#include "expr.h"
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#include "function.h"
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#include "function.h"
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#include "diagnostic.h"
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#include "diagnostic.h"
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#include "timevar.h"
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#include "timevar.h"
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#include "tree-dump.h"
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#include "tree-dump.h"
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#include "tree-flow.h"
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#include "tree-flow.h"
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#include "domwalk.h"
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#include "domwalk.h"
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#include "real.h"
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#include "real.h"
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#include "tree-pass.h"
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#include "tree-pass.h"
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#include "tree-ssa-propagate.h"
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#include "tree-ssa-propagate.h"
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#include "langhooks.h"
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#include "langhooks.h"
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/* The basic structure describing an equivalency created by traversing
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/* The basic structure describing an equivalency created by traversing
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an edge. Traversing the edge effectively means that we can assume
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an edge. Traversing the edge effectively means that we can assume
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that we've seen an assignment LHS = RHS. */
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that we've seen an assignment LHS = RHS. */
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struct edge_equivalency
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struct edge_equivalency
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{
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{
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tree rhs;
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tree rhs;
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tree lhs;
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tree lhs;
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};
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};
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/* This routine finds and records edge equivalences for every edge
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/* This routine finds and records edge equivalences for every edge
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in the CFG.
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in the CFG.
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When complete, each edge that creates an equivalency will have an
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When complete, each edge that creates an equivalency will have an
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EDGE_EQUIVALENCY structure hanging off the edge's AUX field.
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EDGE_EQUIVALENCY structure hanging off the edge's AUX field.
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The caller is responsible for freeing the AUX fields. */
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The caller is responsible for freeing the AUX fields. */
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static void
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static void
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associate_equivalences_with_edges (void)
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associate_equivalences_with_edges (void)
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{
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{
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basic_block bb;
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basic_block bb;
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/* Walk over each block. If the block ends with a control statement,
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/* Walk over each block. If the block ends with a control statement,
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then it might create a useful equivalence. */
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then it might create a useful equivalence. */
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FOR_EACH_BB (bb)
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FOR_EACH_BB (bb)
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{
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{
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block_stmt_iterator bsi = bsi_last (bb);
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block_stmt_iterator bsi = bsi_last (bb);
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tree stmt;
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tree stmt;
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/* If the block does not end with a COND_EXPR or SWITCH_EXPR
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/* If the block does not end with a COND_EXPR or SWITCH_EXPR
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then there is nothing to do. */
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then there is nothing to do. */
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if (bsi_end_p (bsi))
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if (bsi_end_p (bsi))
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continue;
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continue;
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stmt = bsi_stmt (bsi);
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stmt = bsi_stmt (bsi);
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if (!stmt)
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if (!stmt)
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continue;
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continue;
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/* A COND_EXPR may create an equivalency in a variety of different
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/* A COND_EXPR may create an equivalency in a variety of different
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ways. */
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ways. */
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if (TREE_CODE (stmt) == COND_EXPR)
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if (TREE_CODE (stmt) == COND_EXPR)
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{
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{
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tree cond = COND_EXPR_COND (stmt);
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tree cond = COND_EXPR_COND (stmt);
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edge true_edge;
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edge true_edge;
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edge false_edge;
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edge false_edge;
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struct edge_equivalency *equivalency;
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struct edge_equivalency *equivalency;
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extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
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extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
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/* If the conditional is a single variable 'X', record 'X = 1'
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/* If the conditional is a single variable 'X', record 'X = 1'
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for the true edge and 'X = 0' on the false edge. */
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for the true edge and 'X = 0' on the false edge. */
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if (TREE_CODE (cond) == SSA_NAME
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if (TREE_CODE (cond) == SSA_NAME
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (cond))
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (cond))
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{
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{
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->rhs = constant_boolean_node (1, TREE_TYPE (cond));
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equivalency->rhs = constant_boolean_node (1, TREE_TYPE (cond));
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equivalency->lhs = cond;
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equivalency->lhs = cond;
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true_edge->aux = equivalency;
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true_edge->aux = equivalency;
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->rhs = constant_boolean_node (0, TREE_TYPE (cond));
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equivalency->rhs = constant_boolean_node (0, TREE_TYPE (cond));
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equivalency->lhs = cond;
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equivalency->lhs = cond;
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false_edge->aux = equivalency;
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false_edge->aux = equivalency;
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}
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}
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/* Equality tests may create one or two equivalences. */
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/* Equality tests may create one or two equivalences. */
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else if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
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else if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
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{
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{
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tree op0 = TREE_OPERAND (cond, 0);
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tree op0 = TREE_OPERAND (cond, 0);
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tree op1 = TREE_OPERAND (cond, 1);
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tree op1 = TREE_OPERAND (cond, 1);
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/* Special case comparing booleans against a constant as we
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/* Special case comparing booleans against a constant as we
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know the value of OP0 on both arms of the branch. i.e., we
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know the value of OP0 on both arms of the branch. i.e., we
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can record an equivalence for OP0 rather than COND. */
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can record an equivalence for OP0 rather than COND. */
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if (TREE_CODE (op0) == SSA_NAME
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if (TREE_CODE (op0) == SSA_NAME
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0)
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0)
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&& TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
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&& TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
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&& is_gimple_min_invariant (op1))
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&& is_gimple_min_invariant (op1))
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{
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{
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if (TREE_CODE (cond) == EQ_EXPR)
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if (TREE_CODE (cond) == EQ_EXPR)
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{
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{
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->lhs = op0;
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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equivalency->rhs = (integer_zerop (op1)
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? boolean_false_node
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? boolean_false_node
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: boolean_true_node);
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: boolean_true_node);
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true_edge->aux = equivalency;
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true_edge->aux = equivalency;
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->lhs = op0;
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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equivalency->rhs = (integer_zerop (op1)
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? boolean_true_node
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? boolean_true_node
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: boolean_false_node);
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: boolean_false_node);
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false_edge->aux = equivalency;
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false_edge->aux = equivalency;
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}
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}
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else
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else
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{
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{
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->lhs = op0;
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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equivalency->rhs = (integer_zerop (op1)
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? boolean_true_node
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? boolean_true_node
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: boolean_false_node);
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: boolean_false_node);
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true_edge->aux = equivalency;
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true_edge->aux = equivalency;
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->lhs = op0;
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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equivalency->rhs = (integer_zerop (op1)
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? boolean_false_node
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? boolean_false_node
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: boolean_true_node);
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: boolean_true_node);
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false_edge->aux = equivalency;
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false_edge->aux = equivalency;
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}
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}
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}
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}
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if (TREE_CODE (op0) == SSA_NAME
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if (TREE_CODE (op0) == SSA_NAME
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0)
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0)
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&& (is_gimple_min_invariant (op1)
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&& (is_gimple_min_invariant (op1)
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|| (TREE_CODE (op1) == SSA_NAME
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|| (TREE_CODE (op1) == SSA_NAME
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op1))))
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op1))))
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{
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{
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/* For IEEE, -0.0 == 0.0, so we don't necessarily know
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/* For IEEE, -0.0 == 0.0, so we don't necessarily know
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the sign of a variable compared against zero. If
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the sign of a variable compared against zero. If
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we're honoring signed zeros, then we cannot record
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we're honoring signed zeros, then we cannot record
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this value unless we know that the value is nonzero. */
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this value unless we know that the value is nonzero. */
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if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op0)))
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if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op0)))
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&& (TREE_CODE (op1) != REAL_CST
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&& (TREE_CODE (op1) != REAL_CST
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|| REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (op1))))
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|| REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (op1))))
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continue;
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continue;
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equivalency = XNEW (struct edge_equivalency);
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equivalency = XNEW (struct edge_equivalency);
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equivalency->lhs = op0;
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equivalency->lhs = op0;
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equivalency->rhs = op1;
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equivalency->rhs = op1;
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if (TREE_CODE (cond) == EQ_EXPR)
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if (TREE_CODE (cond) == EQ_EXPR)
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true_edge->aux = equivalency;
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true_edge->aux = equivalency;
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else
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else
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false_edge->aux = equivalency;
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false_edge->aux = equivalency;
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|
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}
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}
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}
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}
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/* ??? TRUTH_NOT_EXPR can create an equivalence too. */
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/* ??? TRUTH_NOT_EXPR can create an equivalence too. */
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}
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}
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/* For a SWITCH_EXPR, a case label which represents a single
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/* For a SWITCH_EXPR, a case label which represents a single
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value and which is the only case label which reaches the
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value and which is the only case label which reaches the
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target block creates an equivalence. */
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target block creates an equivalence. */
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if (TREE_CODE (stmt) == SWITCH_EXPR)
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if (TREE_CODE (stmt) == SWITCH_EXPR)
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{
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{
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tree cond = SWITCH_COND (stmt);
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tree cond = SWITCH_COND (stmt);
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|
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if (TREE_CODE (cond) == SSA_NAME
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if (TREE_CODE (cond) == SSA_NAME
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (cond))
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&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (cond))
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{
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{
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tree labels = SWITCH_LABELS (stmt);
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tree labels = SWITCH_LABELS (stmt);
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int i, n_labels = TREE_VEC_LENGTH (labels);
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int i, n_labels = TREE_VEC_LENGTH (labels);
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tree *info = XCNEWVEC (tree, n_basic_blocks);
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tree *info = XCNEWVEC (tree, n_basic_blocks);
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|
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/* Walk over the case label vector. Record blocks
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/* Walk over the case label vector. Record blocks
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which are reached by a single case label which represents
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which are reached by a single case label which represents
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a single value. */
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a single value. */
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for (i = 0; i < n_labels; i++)
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for (i = 0; i < n_labels; i++)
|
{
|
{
|
tree label = TREE_VEC_ELT (labels, i);
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tree label = TREE_VEC_ELT (labels, i);
|
basic_block bb = label_to_block (CASE_LABEL (label));
|
basic_block bb = label_to_block (CASE_LABEL (label));
|
|
|
|
|
if (CASE_HIGH (label)
|
if (CASE_HIGH (label)
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|| !CASE_LOW (label)
|
|| !CASE_LOW (label)
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|| info[bb->index])
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|| info[bb->index])
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info[bb->index] = error_mark_node;
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info[bb->index] = error_mark_node;
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else
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else
|
info[bb->index] = label;
|
info[bb->index] = label;
|
}
|
}
|
|
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/* Now walk over the blocks to determine which ones were
|
/* Now walk over the blocks to determine which ones were
|
marked as being reached by a useful case label. */
|
marked as being reached by a useful case label. */
|
for (i = 0; i < n_basic_blocks; i++)
|
for (i = 0; i < n_basic_blocks; i++)
|
{
|
{
|
tree node = info[i];
|
tree node = info[i];
|
|
|
if (node != NULL
|
if (node != NULL
|
&& node != error_mark_node)
|
&& node != error_mark_node)
|
{
|
{
|
tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node));
|
tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node));
|
struct edge_equivalency *equivalency;
|
struct edge_equivalency *equivalency;
|
|
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/* Record an equivalency on the edge from BB to basic
|
/* Record an equivalency on the edge from BB to basic
|
block I. */
|
block I. */
|
equivalency = XNEW (struct edge_equivalency);
|
equivalency = XNEW (struct edge_equivalency);
|
equivalency->rhs = x;
|
equivalency->rhs = x;
|
equivalency->lhs = cond;
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equivalency->lhs = cond;
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find_edge (bb, BASIC_BLOCK (i))->aux = equivalency;
|
find_edge (bb, BASIC_BLOCK (i))->aux = equivalency;
|
}
|
}
|
}
|
}
|
free (info);
|
free (info);
|
}
|
}
|
}
|
}
|
|
|
}
|
}
|
}
|
}
|
|
|
|
|
/* Translating out of SSA sometimes requires inserting copies and
|
/* Translating out of SSA sometimes requires inserting copies and
|
constant initializations on edges to eliminate PHI nodes.
|
constant initializations on edges to eliminate PHI nodes.
|
|
|
In some cases those copies and constant initializations are
|
In some cases those copies and constant initializations are
|
redundant because the target already has the value on the
|
redundant because the target already has the value on the
|
RHS of the assignment.
|
RHS of the assignment.
|
|
|
We previously tried to catch these cases after translating
|
We previously tried to catch these cases after translating
|
out of SSA form. However, that code often missed cases. Worse
|
out of SSA form. However, that code often missed cases. Worse
|
yet, the cases it missed were also often missed by the RTL
|
yet, the cases it missed were also often missed by the RTL
|
optimizers. Thus the resulting code had redundant instructions.
|
optimizers. Thus the resulting code had redundant instructions.
|
|
|
This pass attempts to detect these situations before translating
|
This pass attempts to detect these situations before translating
|
out of SSA form.
|
out of SSA form.
|
|
|
The key concept that this pass is built upon is that these
|
The key concept that this pass is built upon is that these
|
redundant copies and constant initializations often occur
|
redundant copies and constant initializations often occur
|
due to constant/copy propagating equivalences resulting from
|
due to constant/copy propagating equivalences resulting from
|
COND_EXPRs and SWITCH_EXPRs.
|
COND_EXPRs and SWITCH_EXPRs.
|
|
|
We want to do those propagations as they can sometimes allow
|
We want to do those propagations as they can sometimes allow
|
the SSA optimizers to do a better job. However, in the cases
|
the SSA optimizers to do a better job. However, in the cases
|
where such propagations do not result in further optimization,
|
where such propagations do not result in further optimization,
|
we would like to "undo" the propagation to avoid the redundant
|
we would like to "undo" the propagation to avoid the redundant
|
copies and constant initializations.
|
copies and constant initializations.
|
|
|
This pass works by first associating equivalences with edges in
|
This pass works by first associating equivalences with edges in
|
the CFG. For example, the edge leading from a SWITCH_EXPR to
|
the CFG. For example, the edge leading from a SWITCH_EXPR to
|
its associated CASE_LABEL will have an equivalency between
|
its associated CASE_LABEL will have an equivalency between
|
SWITCH_COND and the value in the case label.
|
SWITCH_COND and the value in the case label.
|
|
|
Once we have found the edge equivalences, we proceed to walk
|
Once we have found the edge equivalences, we proceed to walk
|
the CFG in dominator order. As we traverse edges we record
|
the CFG in dominator order. As we traverse edges we record
|
equivalences associated with those edges we traverse.
|
equivalences associated with those edges we traverse.
|
|
|
When we encounter a PHI node, we walk its arguments to see if we
|
When we encounter a PHI node, we walk its arguments to see if we
|
have an equivalence for the PHI argument. If so, then we replace
|
have an equivalence for the PHI argument. If so, then we replace
|
the argument.
|
the argument.
|
|
|
Equivalences are looked up based on their value (think of it as
|
Equivalences are looked up based on their value (think of it as
|
the RHS of an assignment). A value may be an SSA_NAME or an
|
the RHS of an assignment). A value may be an SSA_NAME or an
|
invariant. We may have several SSA_NAMEs with the same value,
|
invariant. We may have several SSA_NAMEs with the same value,
|
so with each value we have a list of SSA_NAMEs that have the
|
so with each value we have a list of SSA_NAMEs that have the
|
same value. */
|
same value. */
|
|
|
/* As we enter each block we record the value for any edge equivalency
|
/* As we enter each block we record the value for any edge equivalency
|
leading to this block. If no such edge equivalency exists, then we
|
leading to this block. If no such edge equivalency exists, then we
|
record NULL. These equivalences are live until we leave the dominator
|
record NULL. These equivalences are live until we leave the dominator
|
subtree rooted at the block where we record the equivalency. */
|
subtree rooted at the block where we record the equivalency. */
|
static VEC(tree,heap) *equiv_stack;
|
static VEC(tree,heap) *equiv_stack;
|
|
|
/* Global hash table implementing a mapping from invariant values
|
/* Global hash table implementing a mapping from invariant values
|
to a list of SSA_NAMEs which have the same value. We might be
|
to a list of SSA_NAMEs which have the same value. We might be
|
able to reuse tree-vn for this code. */
|
able to reuse tree-vn for this code. */
|
static htab_t equiv;
|
static htab_t equiv;
|
|
|
/* Main structure for recording equivalences into our hash table. */
|
/* Main structure for recording equivalences into our hash table. */
|
struct equiv_hash_elt
|
struct equiv_hash_elt
|
{
|
{
|
/* The value/key of this entry. */
|
/* The value/key of this entry. */
|
tree value;
|
tree value;
|
|
|
/* List of SSA_NAMEs which have the same value/key. */
|
/* List of SSA_NAMEs which have the same value/key. */
|
VEC(tree,heap) *equivalences;
|
VEC(tree,heap) *equivalences;
|
};
|
};
|
|
|
static void uncprop_initialize_block (struct dom_walk_data *, basic_block);
|
static void uncprop_initialize_block (struct dom_walk_data *, basic_block);
|
static void uncprop_finalize_block (struct dom_walk_data *, basic_block);
|
static void uncprop_finalize_block (struct dom_walk_data *, basic_block);
|
static void uncprop_into_successor_phis (struct dom_walk_data *, basic_block);
|
static void uncprop_into_successor_phis (struct dom_walk_data *, basic_block);
|
|
|
/* Hashing and equality routines for the hash table. */
|
/* Hashing and equality routines for the hash table. */
|
|
|
static hashval_t
|
static hashval_t
|
equiv_hash (const void *p)
|
equiv_hash (const void *p)
|
{
|
{
|
tree value = ((struct equiv_hash_elt *)p)->value;
|
tree value = ((struct equiv_hash_elt *)p)->value;
|
return iterative_hash_expr (value, 0);
|
return iterative_hash_expr (value, 0);
|
}
|
}
|
|
|
static int
|
static int
|
equiv_eq (const void *p1, const void *p2)
|
equiv_eq (const void *p1, const void *p2)
|
{
|
{
|
tree value1 = ((struct equiv_hash_elt *)p1)->value;
|
tree value1 = ((struct equiv_hash_elt *)p1)->value;
|
tree value2 = ((struct equiv_hash_elt *)p2)->value;
|
tree value2 = ((struct equiv_hash_elt *)p2)->value;
|
|
|
return operand_equal_p (value1, value2, 0);
|
return operand_equal_p (value1, value2, 0);
|
}
|
}
|
|
|
/* Free an instance of equiv_hash_elt. */
|
/* Free an instance of equiv_hash_elt. */
|
|
|
static void
|
static void
|
equiv_free (void *p)
|
equiv_free (void *p)
|
{
|
{
|
struct equiv_hash_elt *elt = (struct equiv_hash_elt *) p;
|
struct equiv_hash_elt *elt = (struct equiv_hash_elt *) p;
|
VEC_free (tree, heap, elt->equivalences);
|
VEC_free (tree, heap, elt->equivalences);
|
free (elt);
|
free (elt);
|
}
|
}
|
|
|
/* Remove the most recently recorded equivalency for VALUE. */
|
/* Remove the most recently recorded equivalency for VALUE. */
|
|
|
static void
|
static void
|
remove_equivalence (tree value)
|
remove_equivalence (tree value)
|
{
|
{
|
struct equiv_hash_elt equiv_hash_elt, *equiv_hash_elt_p;
|
struct equiv_hash_elt equiv_hash_elt, *equiv_hash_elt_p;
|
void **slot;
|
void **slot;
|
|
|
equiv_hash_elt.value = value;
|
equiv_hash_elt.value = value;
|
equiv_hash_elt.equivalences = NULL;
|
equiv_hash_elt.equivalences = NULL;
|
|
|
slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT);
|
slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT);
|
|
|
equiv_hash_elt_p = (struct equiv_hash_elt *) *slot;
|
equiv_hash_elt_p = (struct equiv_hash_elt *) *slot;
|
VEC_pop (tree, equiv_hash_elt_p->equivalences);
|
VEC_pop (tree, equiv_hash_elt_p->equivalences);
|
}
|
}
|
|
|
/* Record EQUIVALENCE = VALUE into our hash table. */
|
/* Record EQUIVALENCE = VALUE into our hash table. */
|
|
|
static void
|
static void
|
record_equiv (tree value, tree equivalence)
|
record_equiv (tree value, tree equivalence)
|
{
|
{
|
struct equiv_hash_elt *equiv_hash_elt;
|
struct equiv_hash_elt *equiv_hash_elt;
|
void **slot;
|
void **slot;
|
|
|
equiv_hash_elt = XNEW (struct equiv_hash_elt);
|
equiv_hash_elt = XNEW (struct equiv_hash_elt);
|
equiv_hash_elt->value = value;
|
equiv_hash_elt->value = value;
|
equiv_hash_elt->equivalences = NULL;
|
equiv_hash_elt->equivalences = NULL;
|
|
|
slot = htab_find_slot (equiv, equiv_hash_elt, INSERT);
|
slot = htab_find_slot (equiv, equiv_hash_elt, INSERT);
|
|
|
if (*slot == NULL)
|
if (*slot == NULL)
|
*slot = (void *) equiv_hash_elt;
|
*slot = (void *) equiv_hash_elt;
|
else
|
else
|
free (equiv_hash_elt);
|
free (equiv_hash_elt);
|
|
|
equiv_hash_elt = (struct equiv_hash_elt *) *slot;
|
equiv_hash_elt = (struct equiv_hash_elt *) *slot;
|
|
|
VEC_safe_push (tree, heap, equiv_hash_elt->equivalences, equivalence);
|
VEC_safe_push (tree, heap, equiv_hash_elt->equivalences, equivalence);
|
}
|
}
|
|
|
/* Main driver for un-cprop. */
|
/* Main driver for un-cprop. */
|
|
|
static unsigned int
|
static unsigned int
|
tree_ssa_uncprop (void)
|
tree_ssa_uncprop (void)
|
{
|
{
|
struct dom_walk_data walk_data;
|
struct dom_walk_data walk_data;
|
basic_block bb;
|
basic_block bb;
|
|
|
associate_equivalences_with_edges ();
|
associate_equivalences_with_edges ();
|
|
|
/* Create our global data structures. */
|
/* Create our global data structures. */
|
equiv = htab_create (1024, equiv_hash, equiv_eq, equiv_free);
|
equiv = htab_create (1024, equiv_hash, equiv_eq, equiv_free);
|
equiv_stack = VEC_alloc (tree, heap, 2);
|
equiv_stack = VEC_alloc (tree, heap, 2);
|
|
|
/* We're going to do a dominator walk, so ensure that we have
|
/* We're going to do a dominator walk, so ensure that we have
|
dominance information. */
|
dominance information. */
|
calculate_dominance_info (CDI_DOMINATORS);
|
calculate_dominance_info (CDI_DOMINATORS);
|
|
|
/* Setup callbacks for the generic dominator tree walker. */
|
/* Setup callbacks for the generic dominator tree walker. */
|
walk_data.walk_stmts_backward = false;
|
walk_data.walk_stmts_backward = false;
|
walk_data.dom_direction = CDI_DOMINATORS;
|
walk_data.dom_direction = CDI_DOMINATORS;
|
walk_data.initialize_block_local_data = NULL;
|
walk_data.initialize_block_local_data = NULL;
|
walk_data.before_dom_children_before_stmts = uncprop_initialize_block;
|
walk_data.before_dom_children_before_stmts = uncprop_initialize_block;
|
walk_data.before_dom_children_walk_stmts = NULL;
|
walk_data.before_dom_children_walk_stmts = NULL;
|
walk_data.before_dom_children_after_stmts = uncprop_into_successor_phis;
|
walk_data.before_dom_children_after_stmts = uncprop_into_successor_phis;
|
walk_data.after_dom_children_before_stmts = NULL;
|
walk_data.after_dom_children_before_stmts = NULL;
|
walk_data.after_dom_children_walk_stmts = NULL;
|
walk_data.after_dom_children_walk_stmts = NULL;
|
walk_data.after_dom_children_after_stmts = uncprop_finalize_block;
|
walk_data.after_dom_children_after_stmts = uncprop_finalize_block;
|
walk_data.global_data = NULL;
|
walk_data.global_data = NULL;
|
walk_data.block_local_data_size = 0;
|
walk_data.block_local_data_size = 0;
|
walk_data.interesting_blocks = NULL;
|
walk_data.interesting_blocks = NULL;
|
|
|
/* Now initialize the dominator walker. */
|
/* Now initialize the dominator walker. */
|
init_walk_dominator_tree (&walk_data);
|
init_walk_dominator_tree (&walk_data);
|
|
|
/* Recursively walk the dominator tree undoing unprofitable
|
/* Recursively walk the dominator tree undoing unprofitable
|
constant/copy propagations. */
|
constant/copy propagations. */
|
walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
|
walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
|
|
|
/* Finalize and clean up. */
|
/* Finalize and clean up. */
|
fini_walk_dominator_tree (&walk_data);
|
fini_walk_dominator_tree (&walk_data);
|
|
|
/* EQUIV_STACK should already be empty at this point, so we just
|
/* EQUIV_STACK should already be empty at this point, so we just
|
need to empty elements out of the hash table, free EQUIV_STACK,
|
need to empty elements out of the hash table, free EQUIV_STACK,
|
and cleanup the AUX field on the edges. */
|
and cleanup the AUX field on the edges. */
|
htab_delete (equiv);
|
htab_delete (equiv);
|
VEC_free (tree, heap, equiv_stack);
|
VEC_free (tree, heap, equiv_stack);
|
FOR_EACH_BB (bb)
|
FOR_EACH_BB (bb)
|
{
|
{
|
edge e;
|
edge e;
|
edge_iterator ei;
|
edge_iterator ei;
|
|
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
{
|
{
|
if (e->aux)
|
if (e->aux)
|
{
|
{
|
free (e->aux);
|
free (e->aux);
|
e->aux = NULL;
|
e->aux = NULL;
|
}
|
}
|
}
|
}
|
}
|
}
|
return 0;
|
return 0;
|
}
|
}
|
|
|
|
|
/* We have finished processing the dominator children of BB, perform
|
/* We have finished processing the dominator children of BB, perform
|
any finalization actions in preparation for leaving this node in
|
any finalization actions in preparation for leaving this node in
|
the dominator tree. */
|
the dominator tree. */
|
|
|
static void
|
static void
|
uncprop_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
uncprop_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
basic_block bb ATTRIBUTE_UNUSED)
|
basic_block bb ATTRIBUTE_UNUSED)
|
{
|
{
|
/* Pop the topmost value off the equiv stack. */
|
/* Pop the topmost value off the equiv stack. */
|
tree value = VEC_pop (tree, equiv_stack);
|
tree value = VEC_pop (tree, equiv_stack);
|
|
|
/* If that value was non-null, then pop the topmost equivalency off
|
/* If that value was non-null, then pop the topmost equivalency off
|
its equivalency stack. */
|
its equivalency stack. */
|
if (value != NULL)
|
if (value != NULL)
|
remove_equivalence (value);
|
remove_equivalence (value);
|
}
|
}
|
|
|
/* Unpropagate values from PHI nodes in successor blocks of BB. */
|
/* Unpropagate values from PHI nodes in successor blocks of BB. */
|
|
|
static void
|
static void
|
uncprop_into_successor_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
uncprop_into_successor_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
basic_block bb)
|
basic_block bb)
|
{
|
{
|
edge e;
|
edge e;
|
edge_iterator ei;
|
edge_iterator ei;
|
|
|
/* For each successor edge, first temporarily record any equivalence
|
/* For each successor edge, first temporarily record any equivalence
|
on that edge. Then unpropagate values in any PHI nodes at the
|
on that edge. Then unpropagate values in any PHI nodes at the
|
destination of the edge. Then remove the temporary equivalence. */
|
destination of the edge. Then remove the temporary equivalence. */
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
FOR_EACH_EDGE (e, ei, bb->succs)
|
{
|
{
|
tree phi = phi_nodes (e->dest);
|
tree phi = phi_nodes (e->dest);
|
|
|
/* If there are no PHI nodes in this destination, then there is
|
/* If there are no PHI nodes in this destination, then there is
|
no sense in recording any equivalences. */
|
no sense in recording any equivalences. */
|
if (!phi)
|
if (!phi)
|
continue;
|
continue;
|
|
|
/* Record any equivalency associated with E. */
|
/* Record any equivalency associated with E. */
|
if (e->aux)
|
if (e->aux)
|
{
|
{
|
struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux;
|
struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux;
|
record_equiv (equiv->rhs, equiv->lhs);
|
record_equiv (equiv->rhs, equiv->lhs);
|
}
|
}
|
|
|
/* Walk over the PHI nodes, unpropagating values. */
|
/* Walk over the PHI nodes, unpropagating values. */
|
for ( ; phi; phi = PHI_CHAIN (phi))
|
for ( ; phi; phi = PHI_CHAIN (phi))
|
{
|
{
|
/* Sigh. We'll have more efficient access to this one day. */
|
/* Sigh. We'll have more efficient access to this one day. */
|
tree arg = PHI_ARG_DEF (phi, e->dest_idx);
|
tree arg = PHI_ARG_DEF (phi, e->dest_idx);
|
struct equiv_hash_elt equiv_hash_elt;
|
struct equiv_hash_elt equiv_hash_elt;
|
void **slot;
|
void **slot;
|
|
|
/* If the argument is not an invariant, or refers to the same
|
/* If the argument is not an invariant, or refers to the same
|
underlying variable as the PHI result, then there's no
|
underlying variable as the PHI result, then there's no
|
point in un-propagating the argument. */
|
point in un-propagating the argument. */
|
if (!is_gimple_min_invariant (arg)
|
if (!is_gimple_min_invariant (arg)
|
&& SSA_NAME_VAR (arg) != SSA_NAME_VAR (PHI_RESULT (phi)))
|
&& SSA_NAME_VAR (arg) != SSA_NAME_VAR (PHI_RESULT (phi)))
|
continue;
|
continue;
|
|
|
/* Lookup this argument's value in the hash table. */
|
/* Lookup this argument's value in the hash table. */
|
equiv_hash_elt.value = arg;
|
equiv_hash_elt.value = arg;
|
equiv_hash_elt.equivalences = NULL;
|
equiv_hash_elt.equivalences = NULL;
|
slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT);
|
slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT);
|
|
|
if (slot)
|
if (slot)
|
{
|
{
|
struct equiv_hash_elt *elt = (struct equiv_hash_elt *) *slot;
|
struct equiv_hash_elt *elt = (struct equiv_hash_elt *) *slot;
|
int j;
|
int j;
|
|
|
/* Walk every equivalence with the same value. If we find
|
/* Walk every equivalence with the same value. If we find
|
one with the same underlying variable as the PHI result,
|
one with the same underlying variable as the PHI result,
|
then replace the value in the argument with its equivalent
|
then replace the value in the argument with its equivalent
|
SSA_NAME. Use the most recent equivalence as hopefully
|
SSA_NAME. Use the most recent equivalence as hopefully
|
that results in shortest lifetimes. */
|
that results in shortest lifetimes. */
|
for (j = VEC_length (tree, elt->equivalences) - 1; j >= 0; j--)
|
for (j = VEC_length (tree, elt->equivalences) - 1; j >= 0; j--)
|
{
|
{
|
tree equiv = VEC_index (tree, elt->equivalences, j);
|
tree equiv = VEC_index (tree, elt->equivalences, j);
|
|
|
if (SSA_NAME_VAR (equiv) == SSA_NAME_VAR (PHI_RESULT (phi)))
|
if (SSA_NAME_VAR (equiv) == SSA_NAME_VAR (PHI_RESULT (phi)))
|
{
|
{
|
SET_PHI_ARG_DEF (phi, e->dest_idx, equiv);
|
SET_PHI_ARG_DEF (phi, e->dest_idx, equiv);
|
break;
|
break;
|
}
|
}
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
/* If we had an equivalence associated with this edge, remove it. */
|
/* If we had an equivalence associated with this edge, remove it. */
|
if (e->aux)
|
if (e->aux)
|
{
|
{
|
struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux;
|
struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux;
|
remove_equivalence (equiv->rhs);
|
remove_equivalence (equiv->rhs);
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
/* Ignoring loop backedges, if BB has precisely one incoming edge then
|
/* Ignoring loop backedges, if BB has precisely one incoming edge then
|
return that edge. Otherwise return NULL. */
|
return that edge. Otherwise return NULL. */
|
static edge
|
static edge
|
single_incoming_edge_ignoring_loop_edges (basic_block bb)
|
single_incoming_edge_ignoring_loop_edges (basic_block bb)
|
{
|
{
|
edge retval = NULL;
|
edge retval = NULL;
|
edge e;
|
edge e;
|
edge_iterator ei;
|
edge_iterator ei;
|
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
{
|
{
|
/* A loop back edge can be identified by the destination of
|
/* A loop back edge can be identified by the destination of
|
the edge dominating the source of the edge. */
|
the edge dominating the source of the edge. */
|
if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
|
if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
|
continue;
|
continue;
|
|
|
/* If we have already seen a non-loop edge, then we must have
|
/* If we have already seen a non-loop edge, then we must have
|
multiple incoming non-loop edges and thus we return NULL. */
|
multiple incoming non-loop edges and thus we return NULL. */
|
if (retval)
|
if (retval)
|
return NULL;
|
return NULL;
|
|
|
/* This is the first non-loop incoming edge we have found. Record
|
/* This is the first non-loop incoming edge we have found. Record
|
it. */
|
it. */
|
retval = e;
|
retval = e;
|
}
|
}
|
|
|
return retval;
|
return retval;
|
}
|
}
|
|
|
static void
|
static void
|
uncprop_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
uncprop_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
basic_block bb)
|
basic_block bb)
|
{
|
{
|
basic_block parent;
|
basic_block parent;
|
edge e;
|
edge e;
|
bool recorded = false;
|
bool recorded = false;
|
|
|
/* If this block is dominated by a single incoming edge and that edge
|
/* If this block is dominated by a single incoming edge and that edge
|
has an equivalency, then record the equivalency and push the
|
has an equivalency, then record the equivalency and push the
|
VALUE onto EQUIV_STACK. Else push a NULL entry on EQUIV_STACK. */
|
VALUE onto EQUIV_STACK. Else push a NULL entry on EQUIV_STACK. */
|
parent = get_immediate_dominator (CDI_DOMINATORS, bb);
|
parent = get_immediate_dominator (CDI_DOMINATORS, bb);
|
if (parent)
|
if (parent)
|
{
|
{
|
e = single_incoming_edge_ignoring_loop_edges (bb);
|
e = single_incoming_edge_ignoring_loop_edges (bb);
|
|
|
if (e && e->src == parent && e->aux)
|
if (e && e->src == parent && e->aux)
|
{
|
{
|
struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux;
|
struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux;
|
|
|
record_equiv (equiv->rhs, equiv->lhs);
|
record_equiv (equiv->rhs, equiv->lhs);
|
VEC_safe_push (tree, heap, equiv_stack, equiv->rhs);
|
VEC_safe_push (tree, heap, equiv_stack, equiv->rhs);
|
recorded = true;
|
recorded = true;
|
}
|
}
|
}
|
}
|
|
|
if (!recorded)
|
if (!recorded)
|
VEC_safe_push (tree, heap, equiv_stack, NULL_TREE);
|
VEC_safe_push (tree, heap, equiv_stack, NULL_TREE);
|
}
|
}
|
|
|
static bool
|
static bool
|
gate_uncprop (void)
|
gate_uncprop (void)
|
{
|
{
|
return flag_tree_dom != 0;
|
return flag_tree_dom != 0;
|
}
|
}
|
|
|
struct tree_opt_pass pass_uncprop =
|
struct tree_opt_pass pass_uncprop =
|
{
|
{
|
"uncprop", /* name */
|
"uncprop", /* name */
|
gate_uncprop, /* gate */
|
gate_uncprop, /* gate */
|
tree_ssa_uncprop, /* execute */
|
tree_ssa_uncprop, /* execute */
|
NULL, /* sub */
|
NULL, /* sub */
|
NULL, /* next */
|
NULL, /* next */
|
0, /* static_pass_number */
|
0, /* static_pass_number */
|
TV_TREE_SSA_UNCPROP, /* tv_id */
|
TV_TREE_SSA_UNCPROP, /* tv_id */
|
PROP_cfg | PROP_ssa, /* properties_required */
|
PROP_cfg | PROP_ssa, /* properties_required */
|
0, /* properties_provided */
|
0, /* properties_provided */
|
0, /* properties_destroyed */
|
0, /* properties_destroyed */
|
0, /* todo_flags_start */
|
0, /* todo_flags_start */
|
TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */
|
TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */
|
0 /* letter */
|
0 /* letter */
|
};
|
};
|
|
|
