/* Copy propagation and SSA_NAME replacement support routines.
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/* Copy propagation and SSA_NAME replacement support routines.
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Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010
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Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010
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Free Software Foundation, Inc.
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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 "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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#include "cfgloop.h"
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#include "cfgloop.h"
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/* This file implements the copy propagation pass and provides a
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/* This file implements the copy propagation pass and provides a
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handful of interfaces for performing const/copy propagation and
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handful of interfaces for performing const/copy propagation and
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simple expression replacement which keep variable annotations
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simple expression replacement which keep variable annotations
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up-to-date.
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up-to-date.
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We require that for any copy operation where the RHS and LHS have
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We require that for any copy operation where the RHS and LHS have
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a non-null memory tag the memory tag be the same. It is OK
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a non-null memory tag the memory tag be the same. It is OK
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for one or both of the memory tags to be NULL.
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for one or both of the memory tags to be NULL.
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We also require tracking if a variable is dereferenced in a load or
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We also require tracking if a variable is dereferenced in a load or
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store operation.
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store operation.
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We enforce these requirements by having all copy propagation and
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We enforce these requirements by having all copy propagation and
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replacements of one SSA_NAME with a different SSA_NAME to use the
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replacements of one SSA_NAME with a different SSA_NAME to use the
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APIs defined in this file. */
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APIs defined in this file. */
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/* Return true if we may propagate ORIG into DEST, false otherwise. */
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/* Return true if we may propagate ORIG into DEST, false otherwise. */
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bool
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bool
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may_propagate_copy (tree dest, tree orig)
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may_propagate_copy (tree dest, tree orig)
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{
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{
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tree type_d = TREE_TYPE (dest);
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tree type_d = TREE_TYPE (dest);
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tree type_o = TREE_TYPE (orig);
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tree type_o = TREE_TYPE (orig);
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/* If ORIG flows in from an abnormal edge, it cannot be propagated. */
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/* If ORIG flows in from an abnormal edge, it cannot be propagated. */
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if (TREE_CODE (orig) == SSA_NAME
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if (TREE_CODE (orig) == SSA_NAME
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
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return false;
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return false;
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/* If DEST is an SSA_NAME that flows from an abnormal edge, then it
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/* If DEST is an SSA_NAME that flows from an abnormal edge, then it
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cannot be replaced. */
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cannot be replaced. */
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if (TREE_CODE (dest) == SSA_NAME
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if (TREE_CODE (dest) == SSA_NAME
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
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return false;
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return false;
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/* Do not copy between types for which we *do* need a conversion. */
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/* Do not copy between types for which we *do* need a conversion. */
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if (!useless_type_conversion_p (type_d, type_o))
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if (!useless_type_conversion_p (type_d, type_o))
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return false;
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return false;
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/* Propagating virtual operands is always ok. */
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/* Propagating virtual operands is always ok. */
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if (TREE_CODE (dest) == SSA_NAME && !is_gimple_reg (dest))
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if (TREE_CODE (dest) == SSA_NAME && !is_gimple_reg (dest))
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{
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{
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/* But only between virtual operands. */
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/* But only between virtual operands. */
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gcc_assert (TREE_CODE (orig) == SSA_NAME && !is_gimple_reg (orig));
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gcc_assert (TREE_CODE (orig) == SSA_NAME && !is_gimple_reg (orig));
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return true;
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return true;
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}
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}
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/* Anything else is OK. */
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/* Anything else is OK. */
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return true;
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return true;
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}
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}
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/* Like may_propagate_copy, but use as the destination expression
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/* Like may_propagate_copy, but use as the destination expression
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the principal expression (typically, the RHS) contained in
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the principal expression (typically, the RHS) contained in
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statement DEST. This is more efficient when working with the
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statement DEST. This is more efficient when working with the
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gimple tuples representation. */
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gimple tuples representation. */
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bool
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bool
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may_propagate_copy_into_stmt (gimple dest, tree orig)
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may_propagate_copy_into_stmt (gimple dest, tree orig)
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{
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{
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tree type_d;
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tree type_d;
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tree type_o;
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tree type_o;
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/* If the statement is a switch or a single-rhs assignment,
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/* If the statement is a switch or a single-rhs assignment,
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then the expression to be replaced by the propagation may
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then the expression to be replaced by the propagation may
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be an SSA_NAME. Fortunately, there is an explicit tree
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be an SSA_NAME. Fortunately, there is an explicit tree
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for the expression, so we delegate to may_propagate_copy. */
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for the expression, so we delegate to may_propagate_copy. */
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if (gimple_assign_single_p (dest))
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if (gimple_assign_single_p (dest))
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return may_propagate_copy (gimple_assign_rhs1 (dest), orig);
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return may_propagate_copy (gimple_assign_rhs1 (dest), orig);
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else if (gimple_code (dest) == GIMPLE_SWITCH)
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else if (gimple_code (dest) == GIMPLE_SWITCH)
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return may_propagate_copy (gimple_switch_index (dest), orig);
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return may_propagate_copy (gimple_switch_index (dest), orig);
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/* In other cases, the expression is not materialized, so there
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/* In other cases, the expression is not materialized, so there
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is no destination to pass to may_propagate_copy. On the other
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is no destination to pass to may_propagate_copy. On the other
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hand, the expression cannot be an SSA_NAME, so the analysis
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hand, the expression cannot be an SSA_NAME, so the analysis
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is much simpler. */
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is much simpler. */
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if (TREE_CODE (orig) == SSA_NAME
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if (TREE_CODE (orig) == SSA_NAME
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
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return false;
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return false;
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if (is_gimple_assign (dest))
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if (is_gimple_assign (dest))
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type_d = TREE_TYPE (gimple_assign_lhs (dest));
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type_d = TREE_TYPE (gimple_assign_lhs (dest));
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else if (gimple_code (dest) == GIMPLE_COND)
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else if (gimple_code (dest) == GIMPLE_COND)
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type_d = boolean_type_node;
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type_d = boolean_type_node;
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else if (is_gimple_call (dest)
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else if (is_gimple_call (dest)
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&& gimple_call_lhs (dest) != NULL_TREE)
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&& gimple_call_lhs (dest) != NULL_TREE)
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type_d = TREE_TYPE (gimple_call_lhs (dest));
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type_d = TREE_TYPE (gimple_call_lhs (dest));
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else
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else
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gcc_unreachable ();
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gcc_unreachable ();
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type_o = TREE_TYPE (orig);
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type_o = TREE_TYPE (orig);
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if (!useless_type_conversion_p (type_d, type_o))
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if (!useless_type_conversion_p (type_d, type_o))
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return false;
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return false;
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return true;
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return true;
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}
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}
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/* Similarly, but we know that we're propagating into an ASM_EXPR. */
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/* Similarly, but we know that we're propagating into an ASM_EXPR. */
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bool
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bool
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may_propagate_copy_into_asm (tree dest)
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may_propagate_copy_into_asm (tree dest)
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{
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{
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/* Hard register operands of asms are special. Do not bypass. */
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/* Hard register operands of asms are special. Do not bypass. */
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return !(TREE_CODE (dest) == SSA_NAME
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return !(TREE_CODE (dest) == SSA_NAME
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&& TREE_CODE (SSA_NAME_VAR (dest)) == VAR_DECL
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&& TREE_CODE (SSA_NAME_VAR (dest)) == VAR_DECL
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&& DECL_HARD_REGISTER (SSA_NAME_VAR (dest)));
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&& DECL_HARD_REGISTER (SSA_NAME_VAR (dest)));
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}
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}
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/* Common code for propagate_value and replace_exp.
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/* Common code for propagate_value and replace_exp.
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Replace use operand OP_P with VAL. FOR_PROPAGATION indicates if the
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Replace use operand OP_P with VAL. FOR_PROPAGATION indicates if the
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replacement is done to propagate a value or not. */
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replacement is done to propagate a value or not. */
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static void
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static void
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replace_exp_1 (use_operand_p op_p, tree val,
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replace_exp_1 (use_operand_p op_p, tree val,
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bool for_propagation ATTRIBUTE_UNUSED)
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bool for_propagation ATTRIBUTE_UNUSED)
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{
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{
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#if defined ENABLE_CHECKING
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#if defined ENABLE_CHECKING
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tree op = USE_FROM_PTR (op_p);
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tree op = USE_FROM_PTR (op_p);
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gcc_assert (!(for_propagation
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gcc_assert (!(for_propagation
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&& TREE_CODE (op) == SSA_NAME
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&& TREE_CODE (op) == SSA_NAME
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&& TREE_CODE (val) == SSA_NAME
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&& TREE_CODE (val) == SSA_NAME
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&& !may_propagate_copy (op, val)));
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&& !may_propagate_copy (op, val)));
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#endif
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#endif
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if (TREE_CODE (val) == SSA_NAME)
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if (TREE_CODE (val) == SSA_NAME)
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SET_USE (op_p, val);
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SET_USE (op_p, val);
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else
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else
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SET_USE (op_p, unsave_expr_now (val));
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SET_USE (op_p, unsave_expr_now (val));
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}
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}
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/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
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/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
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into the operand pointed to by OP_P.
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into the operand pointed to by OP_P.
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Use this version for const/copy propagation as it will perform additional
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Use this version for const/copy propagation as it will perform additional
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checks to ensure validity of the const/copy propagation. */
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checks to ensure validity of the const/copy propagation. */
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void
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void
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propagate_value (use_operand_p op_p, tree val)
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propagate_value (use_operand_p op_p, tree val)
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{
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{
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replace_exp_1 (op_p, val, true);
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replace_exp_1 (op_p, val, true);
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}
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}
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/* Replace *OP_P with value VAL (assumed to be a constant or another SSA_NAME).
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/* Replace *OP_P with value VAL (assumed to be a constant or another SSA_NAME).
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Use this version when not const/copy propagating values. For example,
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Use this version when not const/copy propagating values. For example,
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PRE uses this version when building expressions as they would appear
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PRE uses this version when building expressions as they would appear
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in specific blocks taking into account actions of PHI nodes. */
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in specific blocks taking into account actions of PHI nodes. */
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void
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void
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replace_exp (use_operand_p op_p, tree val)
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replace_exp (use_operand_p op_p, tree val)
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{
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{
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replace_exp_1 (op_p, val, false);
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replace_exp_1 (op_p, val, false);
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}
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}
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/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
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/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
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into the tree pointed to by OP_P.
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into the tree pointed to by OP_P.
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Use this version for const/copy propagation when SSA operands are not
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Use this version for const/copy propagation when SSA operands are not
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available. It will perform the additional checks to ensure validity of
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available. It will perform the additional checks to ensure validity of
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the const/copy propagation, but will not update any operand information.
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the const/copy propagation, but will not update any operand information.
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Be sure to mark the stmt as modified. */
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Be sure to mark the stmt as modified. */
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void
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void
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propagate_tree_value (tree *op_p, tree val)
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propagate_tree_value (tree *op_p, tree val)
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{
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{
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#if defined ENABLE_CHECKING
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#if defined ENABLE_CHECKING
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gcc_assert (!(TREE_CODE (val) == SSA_NAME
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gcc_assert (!(TREE_CODE (val) == SSA_NAME
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&& *op_p
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&& *op_p
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&& TREE_CODE (*op_p) == SSA_NAME
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&& TREE_CODE (*op_p) == SSA_NAME
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&& !may_propagate_copy (*op_p, val)));
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&& !may_propagate_copy (*op_p, val)));
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#endif
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#endif
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if (TREE_CODE (val) == SSA_NAME)
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if (TREE_CODE (val) == SSA_NAME)
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*op_p = val;
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*op_p = val;
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else
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else
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*op_p = unsave_expr_now (val);
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*op_p = unsave_expr_now (val);
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}
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}
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/* Like propagate_tree_value, but use as the operand to replace
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/* Like propagate_tree_value, but use as the operand to replace
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the principal expression (typically, the RHS) contained in the
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the principal expression (typically, the RHS) contained in the
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statement referenced by iterator GSI. Note that it is not
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statement referenced by iterator GSI. Note that it is not
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always possible to update the statement in-place, so a new
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always possible to update the statement in-place, so a new
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statement may be created to replace the original. */
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statement may be created to replace the original. */
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void
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void
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propagate_tree_value_into_stmt (gimple_stmt_iterator *gsi, tree val)
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propagate_tree_value_into_stmt (gimple_stmt_iterator *gsi, tree val)
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{
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{
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gimple stmt = gsi_stmt (*gsi);
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gimple stmt = gsi_stmt (*gsi);
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|
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if (is_gimple_assign (stmt))
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if (is_gimple_assign (stmt))
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{
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{
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tree expr = NULL_TREE;
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tree expr = NULL_TREE;
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if (gimple_assign_single_p (stmt))
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if (gimple_assign_single_p (stmt))
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expr = gimple_assign_rhs1 (stmt);
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expr = gimple_assign_rhs1 (stmt);
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propagate_tree_value (&expr, val);
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propagate_tree_value (&expr, val);
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gimple_assign_set_rhs_from_tree (gsi, expr);
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gimple_assign_set_rhs_from_tree (gsi, expr);
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stmt = gsi_stmt (*gsi);
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stmt = gsi_stmt (*gsi);
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}
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}
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else if (gimple_code (stmt) == GIMPLE_COND)
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else if (gimple_code (stmt) == GIMPLE_COND)
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{
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{
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tree lhs = NULL_TREE;
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tree lhs = NULL_TREE;
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tree rhs = fold_convert (TREE_TYPE (val), integer_zero_node);
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tree rhs = fold_convert (TREE_TYPE (val), integer_zero_node);
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propagate_tree_value (&lhs, val);
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propagate_tree_value (&lhs, val);
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gimple_cond_set_code (stmt, NE_EXPR);
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gimple_cond_set_code (stmt, NE_EXPR);
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gimple_cond_set_lhs (stmt, lhs);
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gimple_cond_set_lhs (stmt, lhs);
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gimple_cond_set_rhs (stmt, rhs);
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gimple_cond_set_rhs (stmt, rhs);
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}
|
}
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else if (is_gimple_call (stmt)
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else if (is_gimple_call (stmt)
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&& gimple_call_lhs (stmt) != NULL_TREE)
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&& gimple_call_lhs (stmt) != NULL_TREE)
|
{
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{
|
gimple new_stmt;
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gimple new_stmt;
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|
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tree expr = NULL_TREE;
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tree expr = NULL_TREE;
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propagate_tree_value (&expr, val);
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propagate_tree_value (&expr, val);
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new_stmt = gimple_build_assign (gimple_call_lhs (stmt), expr);
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new_stmt = gimple_build_assign (gimple_call_lhs (stmt), expr);
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move_ssa_defining_stmt_for_defs (new_stmt, stmt);
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move_ssa_defining_stmt_for_defs (new_stmt, stmt);
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gsi_replace (gsi, new_stmt, false);
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gsi_replace (gsi, new_stmt, false);
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}
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}
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else if (gimple_code (stmt) == GIMPLE_SWITCH)
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else if (gimple_code (stmt) == GIMPLE_SWITCH)
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propagate_tree_value (gimple_switch_index_ptr (stmt), val);
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propagate_tree_value (gimple_switch_index_ptr (stmt), val);
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else
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else
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gcc_unreachable ();
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gcc_unreachable ();
|
}
|
}
|
|
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/*---------------------------------------------------------------------------
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/*---------------------------------------------------------------------------
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Copy propagation
|
Copy propagation
|
---------------------------------------------------------------------------*/
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---------------------------------------------------------------------------*/
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/* During propagation, we keep chains of variables that are copies of
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/* During propagation, we keep chains of variables that are copies of
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one another. If variable X_i is a copy of X_j and X_j is a copy of
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one another. If variable X_i is a copy of X_j and X_j is a copy of
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X_k, COPY_OF will contain:
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X_k, COPY_OF will contain:
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|
|
COPY_OF[i].VALUE = X_j
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COPY_OF[i].VALUE = X_j
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COPY_OF[j].VALUE = X_k
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COPY_OF[j].VALUE = X_k
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COPY_OF[k].VALUE = X_k
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COPY_OF[k].VALUE = X_k
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|
|
After propagation, the copy-of value for each variable X_i is
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After propagation, the copy-of value for each variable X_i is
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converted into the final value by walking the copy-of chains and
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converted into the final value by walking the copy-of chains and
|
updating COPY_OF[i].VALUE to be the last element of the chain. */
|
updating COPY_OF[i].VALUE to be the last element of the chain. */
|
static prop_value_t *copy_of;
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static prop_value_t *copy_of;
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|
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/* Used in set_copy_of_val to determine if the last link of a copy-of
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/* Used in set_copy_of_val to determine if the last link of a copy-of
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chain has changed. */
|
chain has changed. */
|
static tree *cached_last_copy_of;
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static tree *cached_last_copy_of;
|
|
|
|
|
/* Return true if this statement may generate a useful copy. */
|
/* Return true if this statement may generate a useful copy. */
|
|
|
static bool
|
static bool
|
stmt_may_generate_copy (gimple stmt)
|
stmt_may_generate_copy (gimple stmt)
|
{
|
{
|
if (gimple_code (stmt) == GIMPLE_PHI)
|
if (gimple_code (stmt) == GIMPLE_PHI)
|
return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt));
|
return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt));
|
|
|
if (gimple_code (stmt) != GIMPLE_ASSIGN)
|
if (gimple_code (stmt) != GIMPLE_ASSIGN)
|
return false;
|
return false;
|
|
|
/* If the statement has volatile operands, it won't generate a
|
/* If the statement has volatile operands, it won't generate a
|
useful copy. */
|
useful copy. */
|
if (gimple_has_volatile_ops (stmt))
|
if (gimple_has_volatile_ops (stmt))
|
return false;
|
return false;
|
|
|
/* Statements with loads and/or stores will never generate a useful copy. */
|
/* Statements with loads and/or stores will never generate a useful copy. */
|
if (gimple_vuse (stmt))
|
if (gimple_vuse (stmt))
|
return false;
|
return false;
|
|
|
/* Otherwise, the only statements that generate useful copies are
|
/* Otherwise, the only statements that generate useful copies are
|
assignments whose RHS is just an SSA name that doesn't flow
|
assignments whose RHS is just an SSA name that doesn't flow
|
through abnormal edges. */
|
through abnormal edges. */
|
return (gimple_assign_rhs_code (stmt) == SSA_NAME
|
return (gimple_assign_rhs_code (stmt) == SSA_NAME
|
&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)));
|
&& !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)));
|
}
|
}
|
|
|
|
|
/* Return the copy-of value for VAR. */
|
/* Return the copy-of value for VAR. */
|
|
|
static inline prop_value_t *
|
static inline prop_value_t *
|
get_copy_of_val (tree var)
|
get_copy_of_val (tree var)
|
{
|
{
|
prop_value_t *val = ©_of[SSA_NAME_VERSION (var)];
|
prop_value_t *val = ©_of[SSA_NAME_VERSION (var)];
|
|
|
if (val->value == NULL_TREE
|
if (val->value == NULL_TREE
|
&& !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var)))
|
&& !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var)))
|
{
|
{
|
/* If the variable will never generate a useful copy relation,
|
/* If the variable will never generate a useful copy relation,
|
make it its own copy. */
|
make it its own copy. */
|
val->value = var;
|
val->value = var;
|
}
|
}
|
|
|
return val;
|
return val;
|
}
|
}
|
|
|
|
|
/* Return last link in the copy-of chain for VAR. */
|
/* Return last link in the copy-of chain for VAR. */
|
|
|
static tree
|
static tree
|
get_last_copy_of (tree var)
|
get_last_copy_of (tree var)
|
{
|
{
|
tree last;
|
tree last;
|
int i;
|
int i;
|
|
|
/* Traverse COPY_OF starting at VAR until we get to the last
|
/* Traverse COPY_OF starting at VAR until we get to the last
|
link in the chain. Since it is possible to have cycles in PHI
|
link in the chain. Since it is possible to have cycles in PHI
|
nodes, the copy-of chain may also contain cycles.
|
nodes, the copy-of chain may also contain cycles.
|
|
|
To avoid infinite loops and to avoid traversing lengthy copy-of
|
To avoid infinite loops and to avoid traversing lengthy copy-of
|
chains, we artificially limit the maximum number of chains we are
|
chains, we artificially limit the maximum number of chains we are
|
willing to traverse.
|
willing to traverse.
|
|
|
The value 5 was taken from a compiler and runtime library
|
The value 5 was taken from a compiler and runtime library
|
bootstrap and a mixture of C and C++ code from various sources.
|
bootstrap and a mixture of C and C++ code from various sources.
|
More than 82% of all copy-of chains were shorter than 5 links. */
|
More than 82% of all copy-of chains were shorter than 5 links. */
|
#define LIMIT 5
|
#define LIMIT 5
|
|
|
last = var;
|
last = var;
|
for (i = 0; i < LIMIT; i++)
|
for (i = 0; i < LIMIT; i++)
|
{
|
{
|
tree copy = copy_of[SSA_NAME_VERSION (last)].value;
|
tree copy = copy_of[SSA_NAME_VERSION (last)].value;
|
if (copy == NULL_TREE || copy == last)
|
if (copy == NULL_TREE || copy == last)
|
break;
|
break;
|
last = copy;
|
last = copy;
|
}
|
}
|
|
|
/* If we have reached the limit, then we are either in a copy-of
|
/* If we have reached the limit, then we are either in a copy-of
|
cycle or the copy-of chain is too long. In this case, just
|
cycle or the copy-of chain is too long. In this case, just
|
return VAR so that it is not considered a copy of anything. */
|
return VAR so that it is not considered a copy of anything. */
|
return (i < LIMIT ? last : var);
|
return (i < LIMIT ? last : var);
|
}
|
}
|
|
|
|
|
/* Set FIRST to be the first variable in the copy-of chain for DEST.
|
/* Set FIRST to be the first variable in the copy-of chain for DEST.
|
If DEST's copy-of value or its copy-of chain has changed, return
|
If DEST's copy-of value or its copy-of chain has changed, return
|
true.
|
true.
|
|
|
MEM_REF is the memory reference where FIRST is stored. This is
|
MEM_REF is the memory reference where FIRST is stored. This is
|
used when DEST is a non-register and we are copy propagating loads
|
used when DEST is a non-register and we are copy propagating loads
|
and stores. */
|
and stores. */
|
|
|
static inline bool
|
static inline bool
|
set_copy_of_val (tree dest, tree first)
|
set_copy_of_val (tree dest, tree first)
|
{
|
{
|
unsigned int dest_ver = SSA_NAME_VERSION (dest);
|
unsigned int dest_ver = SSA_NAME_VERSION (dest);
|
tree old_first, old_last, new_last;
|
tree old_first, old_last, new_last;
|
|
|
/* Set FIRST to be the first link in COPY_OF[DEST]. If that
|
/* Set FIRST to be the first link in COPY_OF[DEST]. If that
|
changed, return true. */
|
changed, return true. */
|
old_first = copy_of[dest_ver].value;
|
old_first = copy_of[dest_ver].value;
|
copy_of[dest_ver].value = first;
|
copy_of[dest_ver].value = first;
|
|
|
if (old_first != first)
|
if (old_first != first)
|
return true;
|
return true;
|
|
|
/* If FIRST and OLD_FIRST are the same, we need to check whether the
|
/* If FIRST and OLD_FIRST are the same, we need to check whether the
|
copy-of chain starting at FIRST ends in a different variable. If
|
copy-of chain starting at FIRST ends in a different variable. If
|
the copy-of chain starting at FIRST ends up in a different
|
the copy-of chain starting at FIRST ends up in a different
|
variable than the last cached value we had for DEST, then return
|
variable than the last cached value we had for DEST, then return
|
true because DEST is now a copy of a different variable.
|
true because DEST is now a copy of a different variable.
|
|
|
This test is necessary because even though the first link in the
|
This test is necessary because even though the first link in the
|
copy-of chain may not have changed, if any of the variables in
|
copy-of chain may not have changed, if any of the variables in
|
the copy-of chain changed its final value, DEST will now be the
|
the copy-of chain changed its final value, DEST will now be the
|
copy of a different variable, so we have to do another round of
|
copy of a different variable, so we have to do another round of
|
propagation for everything that depends on DEST. */
|
propagation for everything that depends on DEST. */
|
old_last = cached_last_copy_of[dest_ver];
|
old_last = cached_last_copy_of[dest_ver];
|
new_last = get_last_copy_of (dest);
|
new_last = get_last_copy_of (dest);
|
cached_last_copy_of[dest_ver] = new_last;
|
cached_last_copy_of[dest_ver] = new_last;
|
|
|
return (old_last != new_last);
|
return (old_last != new_last);
|
}
|
}
|
|
|
|
|
/* Dump the copy-of value for variable VAR to FILE. */
|
/* Dump the copy-of value for variable VAR to FILE. */
|
|
|
static void
|
static void
|
dump_copy_of (FILE *file, tree var)
|
dump_copy_of (FILE *file, tree var)
|
{
|
{
|
tree val;
|
tree val;
|
sbitmap visited;
|
sbitmap visited;
|
|
|
print_generic_expr (file, var, dump_flags);
|
print_generic_expr (file, var, dump_flags);
|
|
|
if (TREE_CODE (var) != SSA_NAME)
|
if (TREE_CODE (var) != SSA_NAME)
|
return;
|
return;
|
|
|
visited = sbitmap_alloc (num_ssa_names);
|
visited = sbitmap_alloc (num_ssa_names);
|
sbitmap_zero (visited);
|
sbitmap_zero (visited);
|
SET_BIT (visited, SSA_NAME_VERSION (var));
|
SET_BIT (visited, SSA_NAME_VERSION (var));
|
|
|
fprintf (file, " copy-of chain: ");
|
fprintf (file, " copy-of chain: ");
|
|
|
val = var;
|
val = var;
|
print_generic_expr (file, val, 0);
|
print_generic_expr (file, val, 0);
|
fprintf (file, " ");
|
fprintf (file, " ");
|
while (copy_of[SSA_NAME_VERSION (val)].value)
|
while (copy_of[SSA_NAME_VERSION (val)].value)
|
{
|
{
|
fprintf (file, "-> ");
|
fprintf (file, "-> ");
|
val = copy_of[SSA_NAME_VERSION (val)].value;
|
val = copy_of[SSA_NAME_VERSION (val)].value;
|
print_generic_expr (file, val, 0);
|
print_generic_expr (file, val, 0);
|
fprintf (file, " ");
|
fprintf (file, " ");
|
if (TEST_BIT (visited, SSA_NAME_VERSION (val)))
|
if (TEST_BIT (visited, SSA_NAME_VERSION (val)))
|
break;
|
break;
|
SET_BIT (visited, SSA_NAME_VERSION (val));
|
SET_BIT (visited, SSA_NAME_VERSION (val));
|
}
|
}
|
|
|
val = get_copy_of_val (var)->value;
|
val = get_copy_of_val (var)->value;
|
if (val == NULL_TREE)
|
if (val == NULL_TREE)
|
fprintf (file, "[UNDEFINED]");
|
fprintf (file, "[UNDEFINED]");
|
else if (val != var)
|
else if (val != var)
|
fprintf (file, "[COPY]");
|
fprintf (file, "[COPY]");
|
else
|
else
|
fprintf (file, "[NOT A COPY]");
|
fprintf (file, "[NOT A COPY]");
|
|
|
sbitmap_free (visited);
|
sbitmap_free (visited);
|
}
|
}
|
|
|
|
|
/* Evaluate the RHS of STMT. If it produces a valid copy, set the LHS
|
/* Evaluate the RHS of STMT. If it produces a valid copy, set the LHS
|
value and store the LHS into *RESULT_P. If STMT generates more
|
value and store the LHS into *RESULT_P. If STMT generates more
|
than one name (i.e., STMT is an aliased store), it is enough to
|
than one name (i.e., STMT is an aliased store), it is enough to
|
store the first name in the VDEF list into *RESULT_P. After
|
store the first name in the VDEF list into *RESULT_P. After
|
all, the names generated will be VUSEd in the same statements. */
|
all, the names generated will be VUSEd in the same statements. */
|
|
|
static enum ssa_prop_result
|
static enum ssa_prop_result
|
copy_prop_visit_assignment (gimple stmt, tree *result_p)
|
copy_prop_visit_assignment (gimple stmt, tree *result_p)
|
{
|
{
|
tree lhs, rhs;
|
tree lhs, rhs;
|
prop_value_t *rhs_val;
|
prop_value_t *rhs_val;
|
|
|
lhs = gimple_assign_lhs (stmt);
|
lhs = gimple_assign_lhs (stmt);
|
rhs = gimple_assign_rhs1 (stmt);
|
rhs = gimple_assign_rhs1 (stmt);
|
|
|
|
|
gcc_assert (gimple_assign_rhs_code (stmt) == SSA_NAME);
|
gcc_assert (gimple_assign_rhs_code (stmt) == SSA_NAME);
|
|
|
rhs_val = get_copy_of_val (rhs);
|
rhs_val = get_copy_of_val (rhs);
|
|
|
if (TREE_CODE (lhs) == SSA_NAME)
|
if (TREE_CODE (lhs) == SSA_NAME)
|
{
|
{
|
/* Straight copy between two SSA names. First, make sure that
|
/* Straight copy between two SSA names. First, make sure that
|
we can propagate the RHS into uses of LHS. */
|
we can propagate the RHS into uses of LHS. */
|
if (!may_propagate_copy (lhs, rhs))
|
if (!may_propagate_copy (lhs, rhs))
|
return SSA_PROP_VARYING;
|
return SSA_PROP_VARYING;
|
|
|
/* Notice that in the case of assignments, we make the LHS be a
|
/* Notice that in the case of assignments, we make the LHS be a
|
copy of RHS's value, not of RHS itself. This avoids keeping
|
copy of RHS's value, not of RHS itself. This avoids keeping
|
unnecessary copy-of chains (assignments cannot be in a cycle
|
unnecessary copy-of chains (assignments cannot be in a cycle
|
like PHI nodes), speeding up the propagation process.
|
like PHI nodes), speeding up the propagation process.
|
This is different from what we do in copy_prop_visit_phi_node.
|
This is different from what we do in copy_prop_visit_phi_node.
|
In those cases, we are interested in the copy-of chains. */
|
In those cases, we are interested in the copy-of chains. */
|
*result_p = lhs;
|
*result_p = lhs;
|
if (set_copy_of_val (*result_p, rhs_val->value))
|
if (set_copy_of_val (*result_p, rhs_val->value))
|
return SSA_PROP_INTERESTING;
|
return SSA_PROP_INTERESTING;
|
else
|
else
|
return SSA_PROP_NOT_INTERESTING;
|
return SSA_PROP_NOT_INTERESTING;
|
}
|
}
|
|
|
return SSA_PROP_VARYING;
|
return SSA_PROP_VARYING;
|
}
|
}
|
|
|
|
|
/* Visit the GIMPLE_COND STMT. Return SSA_PROP_INTERESTING
|
/* Visit the GIMPLE_COND STMT. Return SSA_PROP_INTERESTING
|
if it can determine which edge will be taken. Otherwise, return
|
if it can determine which edge will be taken. Otherwise, return
|
SSA_PROP_VARYING. */
|
SSA_PROP_VARYING. */
|
|
|
static enum ssa_prop_result
|
static enum ssa_prop_result
|
copy_prop_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
|
copy_prop_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
|
{
|
{
|
enum ssa_prop_result retval = SSA_PROP_VARYING;
|
enum ssa_prop_result retval = SSA_PROP_VARYING;
|
location_t loc = gimple_location (stmt);
|
location_t loc = gimple_location (stmt);
|
|
|
tree op0 = gimple_cond_lhs (stmt);
|
tree op0 = gimple_cond_lhs (stmt);
|
tree op1 = gimple_cond_rhs (stmt);
|
tree op1 = gimple_cond_rhs (stmt);
|
|
|
/* The only conditionals that we may be able to compute statically
|
/* The only conditionals that we may be able to compute statically
|
are predicates involving two SSA_NAMEs. */
|
are predicates involving two SSA_NAMEs. */
|
if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
|
if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
|
{
|
{
|
op0 = get_last_copy_of (op0);
|
op0 = get_last_copy_of (op0);
|
op1 = get_last_copy_of (op1);
|
op1 = get_last_copy_of (op1);
|
|
|
/* See if we can determine the predicate's value. */
|
/* See if we can determine the predicate's value. */
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
{
|
{
|
fprintf (dump_file, "Trying to determine truth value of ");
|
fprintf (dump_file, "Trying to determine truth value of ");
|
fprintf (dump_file, "predicate ");
|
fprintf (dump_file, "predicate ");
|
print_gimple_stmt (dump_file, stmt, 0, 0);
|
print_gimple_stmt (dump_file, stmt, 0, 0);
|
}
|
}
|
|
|
/* We can fold COND and get a useful result only when we have
|
/* We can fold COND and get a useful result only when we have
|
the same SSA_NAME on both sides of a comparison operator. */
|
the same SSA_NAME on both sides of a comparison operator. */
|
if (op0 == op1)
|
if (op0 == op1)
|
{
|
{
|
tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
|
tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
|
boolean_type_node, op0, op1);
|
boolean_type_node, op0, op1);
|
if (folded_cond)
|
if (folded_cond)
|
{
|
{
|
basic_block bb = gimple_bb (stmt);
|
basic_block bb = gimple_bb (stmt);
|
*taken_edge_p = find_taken_edge (bb, folded_cond);
|
*taken_edge_p = find_taken_edge (bb, folded_cond);
|
if (*taken_edge_p)
|
if (*taken_edge_p)
|
retval = SSA_PROP_INTERESTING;
|
retval = SSA_PROP_INTERESTING;
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p)
|
if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p)
|
fprintf (dump_file, "\nConditional will always take edge %d->%d\n",
|
fprintf (dump_file, "\nConditional will always take edge %d->%d\n",
|
(*taken_edge_p)->src->index, (*taken_edge_p)->dest->index);
|
(*taken_edge_p)->src->index, (*taken_edge_p)->dest->index);
|
|
|
return retval;
|
return retval;
|
}
|
}
|
|
|
|
|
/* Evaluate statement STMT. If the statement produces a new output
|
/* Evaluate statement STMT. If the statement produces a new output
|
value, return SSA_PROP_INTERESTING and store the SSA_NAME holding
|
value, return SSA_PROP_INTERESTING and store the SSA_NAME holding
|
the new value in *RESULT_P.
|
the new value in *RESULT_P.
|
|
|
If STMT is a conditional branch and we can determine its truth
|
If STMT is a conditional branch and we can determine its truth
|
value, set *TAKEN_EDGE_P accordingly.
|
value, set *TAKEN_EDGE_P accordingly.
|
|
|
If the new value produced by STMT is varying, return
|
If the new value produced by STMT is varying, return
|
SSA_PROP_VARYING. */
|
SSA_PROP_VARYING. */
|
|
|
static enum ssa_prop_result
|
static enum ssa_prop_result
|
copy_prop_visit_stmt (gimple stmt, edge *taken_edge_p, tree *result_p)
|
copy_prop_visit_stmt (gimple stmt, edge *taken_edge_p, tree *result_p)
|
{
|
{
|
enum ssa_prop_result retval;
|
enum ssa_prop_result retval;
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
{
|
{
|
fprintf (dump_file, "\nVisiting statement:\n");
|
fprintf (dump_file, "\nVisiting statement:\n");
|
print_gimple_stmt (dump_file, stmt, 0, dump_flags);
|
print_gimple_stmt (dump_file, stmt, 0, dump_flags);
|
fprintf (dump_file, "\n");
|
fprintf (dump_file, "\n");
|
}
|
}
|
|
|
if (gimple_assign_single_p (stmt)
|
if (gimple_assign_single_p (stmt)
|
&& TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
|
&& TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
|
&& TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME)
|
&& TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME)
|
{
|
{
|
/* If the statement is a copy assignment, evaluate its RHS to
|
/* If the statement is a copy assignment, evaluate its RHS to
|
see if the lattice value of its output has changed. */
|
see if the lattice value of its output has changed. */
|
retval = copy_prop_visit_assignment (stmt, result_p);
|
retval = copy_prop_visit_assignment (stmt, result_p);
|
}
|
}
|
else if (gimple_code (stmt) == GIMPLE_COND)
|
else if (gimple_code (stmt) == GIMPLE_COND)
|
{
|
{
|
/* See if we can determine which edge goes out of a conditional
|
/* See if we can determine which edge goes out of a conditional
|
jump. */
|
jump. */
|
retval = copy_prop_visit_cond_stmt (stmt, taken_edge_p);
|
retval = copy_prop_visit_cond_stmt (stmt, taken_edge_p);
|
}
|
}
|
else
|
else
|
retval = SSA_PROP_VARYING;
|
retval = SSA_PROP_VARYING;
|
|
|
if (retval == SSA_PROP_VARYING)
|
if (retval == SSA_PROP_VARYING)
|
{
|
{
|
tree def;
|
tree def;
|
ssa_op_iter i;
|
ssa_op_iter i;
|
|
|
/* Any other kind of statement is not interesting for constant
|
/* Any other kind of statement is not interesting for constant
|
propagation and, therefore, not worth simulating. */
|
propagation and, therefore, not worth simulating. */
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
fprintf (dump_file, "No interesting values produced.\n");
|
fprintf (dump_file, "No interesting values produced.\n");
|
|
|
/* The assignment is not a copy operation. Don't visit this
|
/* The assignment is not a copy operation. Don't visit this
|
statement again and mark all the definitions in the statement
|
statement again and mark all the definitions in the statement
|
to be copies of nothing. */
|
to be copies of nothing. */
|
FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS)
|
FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS)
|
set_copy_of_val (def, def);
|
set_copy_of_val (def, def);
|
}
|
}
|
|
|
return retval;
|
return retval;
|
}
|
}
|
|
|
|
|
/* Visit PHI node PHI. If all the arguments produce the same value,
|
/* Visit PHI node PHI. If all the arguments produce the same value,
|
set it to be the value of the LHS of PHI. */
|
set it to be the value of the LHS of PHI. */
|
|
|
static enum ssa_prop_result
|
static enum ssa_prop_result
|
copy_prop_visit_phi_node (gimple phi)
|
copy_prop_visit_phi_node (gimple phi)
|
{
|
{
|
enum ssa_prop_result retval;
|
enum ssa_prop_result retval;
|
unsigned i;
|
unsigned i;
|
prop_value_t phi_val = { 0, NULL_TREE };
|
prop_value_t phi_val = { 0, NULL_TREE };
|
|
|
tree lhs = gimple_phi_result (phi);
|
tree lhs = gimple_phi_result (phi);
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
{
|
{
|
fprintf (dump_file, "\nVisiting PHI node: ");
|
fprintf (dump_file, "\nVisiting PHI node: ");
|
print_gimple_stmt (dump_file, phi, 0, dump_flags);
|
print_gimple_stmt (dump_file, phi, 0, dump_flags);
|
fprintf (dump_file, "\n\n");
|
fprintf (dump_file, "\n\n");
|
}
|
}
|
|
|
for (i = 0; i < gimple_phi_num_args (phi); i++)
|
for (i = 0; i < gimple_phi_num_args (phi); i++)
|
{
|
{
|
prop_value_t *arg_val;
|
prop_value_t *arg_val;
|
tree arg = gimple_phi_arg_def (phi, i);
|
tree arg = gimple_phi_arg_def (phi, i);
|
edge e = gimple_phi_arg_edge (phi, i);
|
edge e = gimple_phi_arg_edge (phi, i);
|
|
|
/* We don't care about values flowing through non-executable
|
/* We don't care about values flowing through non-executable
|
edges. */
|
edges. */
|
if (!(e->flags & EDGE_EXECUTABLE))
|
if (!(e->flags & EDGE_EXECUTABLE))
|
continue;
|
continue;
|
|
|
/* Constants in the argument list never generate a useful copy.
|
/* Constants in the argument list never generate a useful copy.
|
Similarly, names that flow through abnormal edges cannot be
|
Similarly, names that flow through abnormal edges cannot be
|
used to derive copies. */
|
used to derive copies. */
|
if (TREE_CODE (arg) != SSA_NAME || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg))
|
if (TREE_CODE (arg) != SSA_NAME || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg))
|
{
|
{
|
phi_val.value = lhs;
|
phi_val.value = lhs;
|
break;
|
break;
|
}
|
}
|
|
|
/* Avoid copy propagation from an inner into an outer loop.
|
/* Avoid copy propagation from an inner into an outer loop.
|
Otherwise, this may move loop variant variables outside of
|
Otherwise, this may move loop variant variables outside of
|
their loops and prevent coalescing opportunities. If the
|
their loops and prevent coalescing opportunities. If the
|
value was loop invariant, it will be hoisted by LICM and
|
value was loop invariant, it will be hoisted by LICM and
|
exposed for copy propagation. Not a problem for virtual
|
exposed for copy propagation. Not a problem for virtual
|
operands though. */
|
operands though. */
|
if (is_gimple_reg (lhs)
|
if (is_gimple_reg (lhs)
|
&& loop_depth_of_name (arg) > loop_depth_of_name (lhs))
|
&& loop_depth_of_name (arg) > loop_depth_of_name (lhs))
|
{
|
{
|
phi_val.value = lhs;
|
phi_val.value = lhs;
|
break;
|
break;
|
}
|
}
|
|
|
/* If the LHS appears in the argument list, ignore it. It is
|
/* If the LHS appears in the argument list, ignore it. It is
|
irrelevant as a copy. */
|
irrelevant as a copy. */
|
if (arg == lhs || get_last_copy_of (arg) == lhs)
|
if (arg == lhs || get_last_copy_of (arg) == lhs)
|
continue;
|
continue;
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
{
|
{
|
fprintf (dump_file, "\tArgument #%d: ", i);
|
fprintf (dump_file, "\tArgument #%d: ", i);
|
dump_copy_of (dump_file, arg);
|
dump_copy_of (dump_file, arg);
|
fprintf (dump_file, "\n");
|
fprintf (dump_file, "\n");
|
}
|
}
|
|
|
arg_val = get_copy_of_val (arg);
|
arg_val = get_copy_of_val (arg);
|
|
|
/* If the LHS didn't have a value yet, make it a copy of the
|
/* If the LHS didn't have a value yet, make it a copy of the
|
first argument we find. Notice that while we make the LHS be
|
first argument we find. Notice that while we make the LHS be
|
a copy of the argument itself, we take the memory reference
|
a copy of the argument itself, we take the memory reference
|
from the argument's value so that we can compare it to the
|
from the argument's value so that we can compare it to the
|
memory reference of all the other arguments. */
|
memory reference of all the other arguments. */
|
if (phi_val.value == NULL_TREE)
|
if (phi_val.value == NULL_TREE)
|
{
|
{
|
phi_val.value = arg_val->value ? arg_val->value : arg;
|
phi_val.value = arg_val->value ? arg_val->value : arg;
|
continue;
|
continue;
|
}
|
}
|
|
|
/* If PHI_VAL and ARG don't have a common copy-of chain, then
|
/* If PHI_VAL and ARG don't have a common copy-of chain, then
|
this PHI node cannot be a copy operation. Also, if we are
|
this PHI node cannot be a copy operation. Also, if we are
|
copy propagating stores and these two arguments came from
|
copy propagating stores and these two arguments came from
|
different memory references, they cannot be considered
|
different memory references, they cannot be considered
|
copies. */
|
copies. */
|
if (get_last_copy_of (phi_val.value) != get_last_copy_of (arg))
|
if (get_last_copy_of (phi_val.value) != get_last_copy_of (arg))
|
{
|
{
|
phi_val.value = lhs;
|
phi_val.value = lhs;
|
break;
|
break;
|
}
|
}
|
}
|
}
|
|
|
if (phi_val.value && may_propagate_copy (lhs, phi_val.value)
|
if (phi_val.value && may_propagate_copy (lhs, phi_val.value)
|
&& set_copy_of_val (lhs, phi_val.value))
|
&& set_copy_of_val (lhs, phi_val.value))
|
retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
|
retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
|
else
|
else
|
retval = SSA_PROP_NOT_INTERESTING;
|
retval = SSA_PROP_NOT_INTERESTING;
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
{
|
{
|
fprintf (dump_file, "\nPHI node ");
|
fprintf (dump_file, "\nPHI node ");
|
dump_copy_of (dump_file, lhs);
|
dump_copy_of (dump_file, lhs);
|
fprintf (dump_file, "\nTelling the propagator to ");
|
fprintf (dump_file, "\nTelling the propagator to ");
|
if (retval == SSA_PROP_INTERESTING)
|
if (retval == SSA_PROP_INTERESTING)
|
fprintf (dump_file, "add SSA edges out of this PHI and continue.");
|
fprintf (dump_file, "add SSA edges out of this PHI and continue.");
|
else if (retval == SSA_PROP_VARYING)
|
else if (retval == SSA_PROP_VARYING)
|
fprintf (dump_file, "add SSA edges out of this PHI and never visit again.");
|
fprintf (dump_file, "add SSA edges out of this PHI and never visit again.");
|
else
|
else
|
fprintf (dump_file, "do nothing with SSA edges and keep iterating.");
|
fprintf (dump_file, "do nothing with SSA edges and keep iterating.");
|
fprintf (dump_file, "\n\n");
|
fprintf (dump_file, "\n\n");
|
}
|
}
|
|
|
return retval;
|
return retval;
|
}
|
}
|
|
|
|
|
/* Initialize structures used for copy propagation. PHIS_ONLY is true
|
/* Initialize structures used for copy propagation. PHIS_ONLY is true
|
if we should only consider PHI nodes as generating copy propagation
|
if we should only consider PHI nodes as generating copy propagation
|
opportunities. */
|
opportunities. */
|
|
|
static void
|
static void
|
init_copy_prop (void)
|
init_copy_prop (void)
|
{
|
{
|
basic_block bb;
|
basic_block bb;
|
|
|
copy_of = XCNEWVEC (prop_value_t, num_ssa_names);
|
copy_of = XCNEWVEC (prop_value_t, num_ssa_names);
|
|
|
cached_last_copy_of = XCNEWVEC (tree, num_ssa_names);
|
cached_last_copy_of = XCNEWVEC (tree, num_ssa_names);
|
|
|
FOR_EACH_BB (bb)
|
FOR_EACH_BB (bb)
|
{
|
{
|
gimple_stmt_iterator si;
|
gimple_stmt_iterator si;
|
int depth = bb->loop_depth;
|
int depth = bb->loop_depth;
|
bool loop_exit_p = false;
|
bool loop_exit_p = false;
|
|
|
for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
|
for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
|
{
|
{
|
gimple stmt = gsi_stmt (si);
|
gimple stmt = gsi_stmt (si);
|
ssa_op_iter iter;
|
ssa_op_iter iter;
|
tree def;
|
tree def;
|
|
|
/* The only statements that we care about are those that may
|
/* The only statements that we care about are those that may
|
generate useful copies. We also need to mark conditional
|
generate useful copies. We also need to mark conditional
|
jumps so that their outgoing edges are added to the work
|
jumps so that their outgoing edges are added to the work
|
lists of the propagator.
|
lists of the propagator.
|
|
|
Avoid copy propagation from an inner into an outer loop.
|
Avoid copy propagation from an inner into an outer loop.
|
Otherwise, this may move loop variant variables outside of
|
Otherwise, this may move loop variant variables outside of
|
their loops and prevent coalescing opportunities. If the
|
their loops and prevent coalescing opportunities. If the
|
value was loop invariant, it will be hoisted by LICM and
|
value was loop invariant, it will be hoisted by LICM and
|
exposed for copy propagation. */
|
exposed for copy propagation. */
|
if (stmt_ends_bb_p (stmt))
|
if (stmt_ends_bb_p (stmt))
|
prop_set_simulate_again (stmt, true);
|
prop_set_simulate_again (stmt, true);
|
else if (stmt_may_generate_copy (stmt)
|
else if (stmt_may_generate_copy (stmt)
|
/* Since we are iterating over the statements in
|
/* Since we are iterating over the statements in
|
BB, not the phi nodes, STMT will always be an
|
BB, not the phi nodes, STMT will always be an
|
assignment. */
|
assignment. */
|
&& loop_depth_of_name (gimple_assign_rhs1 (stmt)) <= depth)
|
&& loop_depth_of_name (gimple_assign_rhs1 (stmt)) <= depth)
|
prop_set_simulate_again (stmt, true);
|
prop_set_simulate_again (stmt, true);
|
else
|
else
|
prop_set_simulate_again (stmt, false);
|
prop_set_simulate_again (stmt, false);
|
|
|
/* Mark all the outputs of this statement as not being
|
/* Mark all the outputs of this statement as not being
|
the copy of anything. */
|
the copy of anything. */
|
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
|
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
|
if (!prop_simulate_again_p (stmt))
|
if (!prop_simulate_again_p (stmt))
|
set_copy_of_val (def, def);
|
set_copy_of_val (def, def);
|
else
|
else
|
cached_last_copy_of[SSA_NAME_VERSION (def)] = def;
|
cached_last_copy_of[SSA_NAME_VERSION (def)] = def;
|
}
|
}
|
|
|
/* In loop-closed SSA form do not copy-propagate through
|
/* In loop-closed SSA form do not copy-propagate through
|
PHI nodes in blocks with a loop exit edge predecessor. */
|
PHI nodes in blocks with a loop exit edge predecessor. */
|
if (current_loops
|
if (current_loops
|
&& loops_state_satisfies_p (LOOP_CLOSED_SSA))
|
&& loops_state_satisfies_p (LOOP_CLOSED_SSA))
|
{
|
{
|
edge_iterator ei;
|
edge_iterator ei;
|
edge e;
|
edge e;
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
if (loop_exit_edge_p (e->src->loop_father, e))
|
if (loop_exit_edge_p (e->src->loop_father, e))
|
loop_exit_p = true;
|
loop_exit_p = true;
|
}
|
}
|
|
|
for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
|
for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
|
{
|
{
|
gimple phi = gsi_stmt (si);
|
gimple phi = gsi_stmt (si);
|
tree def;
|
tree def;
|
|
|
def = gimple_phi_result (phi);
|
def = gimple_phi_result (phi);
|
if (!is_gimple_reg (def)
|
if (!is_gimple_reg (def)
|
|| loop_exit_p)
|
|| loop_exit_p)
|
prop_set_simulate_again (phi, false);
|
prop_set_simulate_again (phi, false);
|
else
|
else
|
prop_set_simulate_again (phi, true);
|
prop_set_simulate_again (phi, true);
|
|
|
if (!prop_simulate_again_p (phi))
|
if (!prop_simulate_again_p (phi))
|
set_copy_of_val (def, def);
|
set_copy_of_val (def, def);
|
else
|
else
|
cached_last_copy_of[SSA_NAME_VERSION (def)] = def;
|
cached_last_copy_of[SSA_NAME_VERSION (def)] = def;
|
}
|
}
|
}
|
}
|
}
|
}
|
|
|
|
|
/* Deallocate memory used in copy propagation and do final
|
/* Deallocate memory used in copy propagation and do final
|
substitution. */
|
substitution. */
|
|
|
static void
|
static void
|
fini_copy_prop (void)
|
fini_copy_prop (void)
|
{
|
{
|
size_t i;
|
size_t i;
|
prop_value_t *tmp;
|
prop_value_t *tmp;
|
|
|
/* Set the final copy-of value for each variable by traversing the
|
/* Set the final copy-of value for each variable by traversing the
|
copy-of chains. */
|
copy-of chains. */
|
tmp = XCNEWVEC (prop_value_t, num_ssa_names);
|
tmp = XCNEWVEC (prop_value_t, num_ssa_names);
|
for (i = 1; i < num_ssa_names; i++)
|
for (i = 1; i < num_ssa_names; i++)
|
{
|
{
|
tree var = ssa_name (i);
|
tree var = ssa_name (i);
|
if (!var
|
if (!var
|
|| !copy_of[i].value
|
|| !copy_of[i].value
|
|| copy_of[i].value == var)
|
|| copy_of[i].value == var)
|
continue;
|
continue;
|
|
|
tmp[i].value = get_last_copy_of (var);
|
tmp[i].value = get_last_copy_of (var);
|
|
|
/* In theory the points-to solution of all members of the
|
/* In theory the points-to solution of all members of the
|
copy chain is their intersection. For now we do not bother
|
copy chain is their intersection. For now we do not bother
|
to compute this but only make sure we do not lose points-to
|
to compute this but only make sure we do not lose points-to
|
information completely by setting the points-to solution
|
information completely by setting the points-to solution
|
of the representative to the first solution we find if
|
of the representative to the first solution we find if
|
it doesn't have one already. */
|
it doesn't have one already. */
|
if (tmp[i].value != var
|
if (tmp[i].value != var
|
&& POINTER_TYPE_P (TREE_TYPE (var))
|
&& POINTER_TYPE_P (TREE_TYPE (var))
|
&& SSA_NAME_PTR_INFO (var)
|
&& SSA_NAME_PTR_INFO (var)
|
&& !SSA_NAME_PTR_INFO (tmp[i].value))
|
&& !SSA_NAME_PTR_INFO (tmp[i].value))
|
duplicate_ssa_name_ptr_info (tmp[i].value, SSA_NAME_PTR_INFO (var));
|
duplicate_ssa_name_ptr_info (tmp[i].value, SSA_NAME_PTR_INFO (var));
|
}
|
}
|
|
|
substitute_and_fold (tmp, NULL, true);
|
substitute_and_fold (tmp, NULL, true);
|
|
|
free (cached_last_copy_of);
|
free (cached_last_copy_of);
|
free (copy_of);
|
free (copy_of);
|
free (tmp);
|
free (tmp);
|
}
|
}
|
|
|
|
|
/* Main entry point to the copy propagator.
|
/* Main entry point to the copy propagator.
|
|
|
PHIS_ONLY is true if we should only consider PHI nodes as generating
|
PHIS_ONLY is true if we should only consider PHI nodes as generating
|
copy propagation opportunities.
|
copy propagation opportunities.
|
|
|
The algorithm propagates the value COPY-OF using ssa_propagate. For
|
The algorithm propagates the value COPY-OF using ssa_propagate. For
|
every variable X_i, COPY-OF(X_i) indicates which variable is X_i created
|
every variable X_i, COPY-OF(X_i) indicates which variable is X_i created
|
from. The following example shows how the algorithm proceeds at a
|
from. The following example shows how the algorithm proceeds at a
|
high level:
|
high level:
|
|
|
1 a_24 = x_1
|
1 a_24 = x_1
|
2 a_2 = PHI <a_24, x_1>
|
2 a_2 = PHI <a_24, x_1>
|
3 a_5 = PHI <a_2>
|
3 a_5 = PHI <a_2>
|
4 x_1 = PHI <x_298, a_5, a_2>
|
4 x_1 = PHI <x_298, a_5, a_2>
|
|
|
The end result should be that a_2, a_5, a_24 and x_1 are a copy of
|
The end result should be that a_2, a_5, a_24 and x_1 are a copy of
|
x_298. Propagation proceeds as follows.
|
x_298. Propagation proceeds as follows.
|
|
|
Visit #1: a_24 is copy-of x_1. Value changed.
|
Visit #1: a_24 is copy-of x_1. Value changed.
|
Visit #2: a_2 is copy-of x_1. Value changed.
|
Visit #2: a_2 is copy-of x_1. Value changed.
|
Visit #3: a_5 is copy-of x_1. Value changed.
|
Visit #3: a_5 is copy-of x_1. Value changed.
|
Visit #4: x_1 is copy-of x_298. Value changed.
|
Visit #4: x_1 is copy-of x_298. Value changed.
|
Visit #1: a_24 is copy-of x_298. Value changed.
|
Visit #1: a_24 is copy-of x_298. Value changed.
|
Visit #2: a_2 is copy-of x_298. Value changed.
|
Visit #2: a_2 is copy-of x_298. Value changed.
|
Visit #3: a_5 is copy-of x_298. Value changed.
|
Visit #3: a_5 is copy-of x_298. Value changed.
|
Visit #4: x_1 is copy-of x_298. Stable state reached.
|
Visit #4: x_1 is copy-of x_298. Stable state reached.
|
|
|
When visiting PHI nodes, we only consider arguments that flow
|
When visiting PHI nodes, we only consider arguments that flow
|
through edges marked executable by the propagation engine. So,
|
through edges marked executable by the propagation engine. So,
|
when visiting statement #2 for the first time, we will only look at
|
when visiting statement #2 for the first time, we will only look at
|
the first argument (a_24) and optimistically assume that its value
|
the first argument (a_24) and optimistically assume that its value
|
is the copy of a_24 (x_1).
|
is the copy of a_24 (x_1).
|
|
|
The problem with this approach is that it may fail to discover copy
|
The problem with this approach is that it may fail to discover copy
|
relations in PHI cycles. Instead of propagating copy-of
|
relations in PHI cycles. Instead of propagating copy-of
|
values, we actually propagate copy-of chains. For instance:
|
values, we actually propagate copy-of chains. For instance:
|
|
|
A_3 = B_1;
|
A_3 = B_1;
|
C_9 = A_3;
|
C_9 = A_3;
|
D_4 = C_9;
|
D_4 = C_9;
|
X_i = D_4;
|
X_i = D_4;
|
|
|
In this code fragment, COPY-OF (X_i) = { D_4, C_9, A_3, B_1 }.
|
In this code fragment, COPY-OF (X_i) = { D_4, C_9, A_3, B_1 }.
|
Obviously, we are only really interested in the last value of the
|
Obviously, we are only really interested in the last value of the
|
chain, however the propagator needs to access the copy-of chain
|
chain, however the propagator needs to access the copy-of chain
|
when visiting PHI nodes.
|
when visiting PHI nodes.
|
|
|
To represent the copy-of chain, we use the array COPY_CHAINS, which
|
To represent the copy-of chain, we use the array COPY_CHAINS, which
|
holds the first link in the copy-of chain for every variable.
|
holds the first link in the copy-of chain for every variable.
|
If variable X_i is a copy of X_j, which in turn is a copy of X_k,
|
If variable X_i is a copy of X_j, which in turn is a copy of X_k,
|
the array will contain:
|
the array will contain:
|
|
|
COPY_CHAINS[i] = X_j
|
COPY_CHAINS[i] = X_j
|
COPY_CHAINS[j] = X_k
|
COPY_CHAINS[j] = X_k
|
COPY_CHAINS[k] = X_k
|
COPY_CHAINS[k] = X_k
|
|
|
Keeping copy-of chains instead of copy-of values directly becomes
|
Keeping copy-of chains instead of copy-of values directly becomes
|
important when visiting PHI nodes. Suppose that we had the
|
important when visiting PHI nodes. Suppose that we had the
|
following PHI cycle, such that x_52 is already considered a copy of
|
following PHI cycle, such that x_52 is already considered a copy of
|
x_53:
|
x_53:
|
|
|
1 x_54 = PHI <x_53, x_52>
|
1 x_54 = PHI <x_53, x_52>
|
2 x_53 = PHI <x_898, x_54>
|
2 x_53 = PHI <x_898, x_54>
|
|
|
Visit #1: x_54 is copy-of x_53 (because x_52 is copy-of x_53)
|
Visit #1: x_54 is copy-of x_53 (because x_52 is copy-of x_53)
|
Visit #2: x_53 is copy-of x_898 (because x_54 is a copy of x_53,
|
Visit #2: x_53 is copy-of x_898 (because x_54 is a copy of x_53,
|
so it is considered irrelevant
|
so it is considered irrelevant
|
as a copy).
|
as a copy).
|
Visit #1: x_54 is copy-of nothing (x_53 is a copy-of x_898 and
|
Visit #1: x_54 is copy-of nothing (x_53 is a copy-of x_898 and
|
x_52 is a copy of x_53, so
|
x_52 is a copy of x_53, so
|
they don't match)
|
they don't match)
|
Visit #2: x_53 is copy-of nothing
|
Visit #2: x_53 is copy-of nothing
|
|
|
This problem is avoided by keeping a chain of copies, instead of
|
This problem is avoided by keeping a chain of copies, instead of
|
the final copy-of value. Propagation will now only keep the first
|
the final copy-of value. Propagation will now only keep the first
|
element of a variable's copy-of chain. When visiting PHI nodes,
|
element of a variable's copy-of chain. When visiting PHI nodes,
|
arguments are considered equal if their copy-of chains end in the
|
arguments are considered equal if their copy-of chains end in the
|
same variable. So, as long as their copy-of chains overlap, we
|
same variable. So, as long as their copy-of chains overlap, we
|
know that they will be a copy of the same variable, regardless of
|
know that they will be a copy of the same variable, regardless of
|
which variable that may be).
|
which variable that may be).
|
|
|
Propagation would then proceed as follows (the notation a -> b
|
Propagation would then proceed as follows (the notation a -> b
|
means that a is a copy-of b):
|
means that a is a copy-of b):
|
|
|
Visit #1: x_54 = PHI <x_53, x_52>
|
Visit #1: x_54 = PHI <x_53, x_52>
|
x_53 -> x_53
|
x_53 -> x_53
|
x_52 -> x_53
|
x_52 -> x_53
|
Result: x_54 -> x_53. Value changed. Add SSA edges.
|
Result: x_54 -> x_53. Value changed. Add SSA edges.
|
|
|
Visit #1: x_53 = PHI <x_898, x_54>
|
Visit #1: x_53 = PHI <x_898, x_54>
|
x_898 -> x_898
|
x_898 -> x_898
|
x_54 -> x_53
|
x_54 -> x_53
|
Result: x_53 -> x_898. Value changed. Add SSA edges.
|
Result: x_53 -> x_898. Value changed. Add SSA edges.
|
|
|
Visit #2: x_54 = PHI <x_53, x_52>
|
Visit #2: x_54 = PHI <x_53, x_52>
|
x_53 -> x_898
|
x_53 -> x_898
|
x_52 -> x_53 -> x_898
|
x_52 -> x_53 -> x_898
|
Result: x_54 -> x_898. Value changed. Add SSA edges.
|
Result: x_54 -> x_898. Value changed. Add SSA edges.
|
|
|
Visit #2: x_53 = PHI <x_898, x_54>
|
Visit #2: x_53 = PHI <x_898, x_54>
|
x_898 -> x_898
|
x_898 -> x_898
|
x_54 -> x_898
|
x_54 -> x_898
|
Result: x_53 -> x_898. Value didn't change. Stable state
|
Result: x_53 -> x_898. Value didn't change. Stable state
|
|
|
Once the propagator stabilizes, we end up with the desired result
|
Once the propagator stabilizes, we end up with the desired result
|
x_53 and x_54 are both copies of x_898. */
|
x_53 and x_54 are both copies of x_898. */
|
|
|
static unsigned int
|
static unsigned int
|
execute_copy_prop (void)
|
execute_copy_prop (void)
|
{
|
{
|
init_copy_prop ();
|
init_copy_prop ();
|
ssa_propagate (copy_prop_visit_stmt, copy_prop_visit_phi_node);
|
ssa_propagate (copy_prop_visit_stmt, copy_prop_visit_phi_node);
|
fini_copy_prop ();
|
fini_copy_prop ();
|
return 0;
|
return 0;
|
}
|
}
|
|
|
static bool
|
static bool
|
gate_copy_prop (void)
|
gate_copy_prop (void)
|
{
|
{
|
return flag_tree_copy_prop != 0;
|
return flag_tree_copy_prop != 0;
|
}
|
}
|
|
|
struct gimple_opt_pass pass_copy_prop =
|
struct gimple_opt_pass pass_copy_prop =
|
{
|
{
|
{
|
{
|
GIMPLE_PASS,
|
GIMPLE_PASS,
|
"copyprop", /* name */
|
"copyprop", /* name */
|
gate_copy_prop, /* gate */
|
gate_copy_prop, /* gate */
|
execute_copy_prop, /* execute */
|
execute_copy_prop, /* execute */
|
NULL, /* sub */
|
NULL, /* sub */
|
NULL, /* next */
|
NULL, /* next */
|
0, /* static_pass_number */
|
0, /* static_pass_number */
|
TV_TREE_COPY_PROP, /* tv_id */
|
TV_TREE_COPY_PROP, /* tv_id */
|
PROP_ssa | PROP_cfg, /* properties_required */
|
PROP_ssa | PROP_cfg, /* properties_required */
|
0, /* properties_provided */
|
0, /* properties_provided */
|
0, /* properties_destroyed */
|
0, /* properties_destroyed */
|
0, /* todo_flags_start */
|
0, /* todo_flags_start */
|
TODO_cleanup_cfg
|
TODO_cleanup_cfg
|
| TODO_dump_func
|
| TODO_dump_func
|
| TODO_ggc_collect
|
| TODO_ggc_collect
|
| TODO_verify_ssa
|
| TODO_verify_ssa
|
| TODO_update_ssa /* todo_flags_finish */
|
| TODO_update_ssa /* todo_flags_finish */
|
}
|
}
|
};
|
};
|
|
|
