1363 lines
40 KiB
C
1363 lines
40 KiB
C
/* Forward propagation of expressions for single use variables.
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Copyright (C) 2004, 2005, 2007 Free Software Foundation, Inc.
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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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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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any later version.
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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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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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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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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "ggc.h"
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#include "tree.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "basic-block.h"
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#include "timevar.h"
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#include "diagnostic.h"
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#include "tree-flow.h"
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#include "tree-pass.h"
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#include "tree-dump.h"
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#include "langhooks.h"
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#include "flags.h"
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/* This pass propagates the RHS of assignment statements into use
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sites of the LHS of the assignment. It's basically a specialized
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form of tree combination. It is hoped all of this can disappear
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when we have a generalized tree combiner.
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Note carefully that after propagation the resulting statement
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must still be a proper gimple statement. Right now we simply
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only perform propagations we know will result in valid gimple
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code. One day we'll want to generalize this code.
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One class of common cases we handle is forward propagating a single use
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variable into a COND_EXPR.
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bb0:
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x = a COND b;
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if (x) goto ... else goto ...
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Will be transformed into:
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bb0:
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if (a COND b) goto ... else goto ...
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Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
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Or (assuming c1 and c2 are constants):
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bb0:
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x = a + c1;
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if (x EQ/NEQ c2) goto ... else goto ...
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Will be transformed into:
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bb0:
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if (a EQ/NEQ (c2 - c1)) goto ... else goto ...
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Similarly for x = a - c1.
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Or
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bb0:
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x = !a
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if (x) goto ... else goto ...
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Will be transformed into:
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bb0:
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if (a == 0) goto ... else goto ...
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Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
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For these cases, we propagate A into all, possibly more than one,
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COND_EXPRs that use X.
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Or
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bb0:
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x = (typecast) a
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if (x) goto ... else goto ...
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Will be transformed into:
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bb0:
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if (a != 0) goto ... else goto ...
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(Assuming a is an integral type and x is a boolean or x is an
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integral and a is a boolean.)
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Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
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For these cases, we propagate A into all, possibly more than one,
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COND_EXPRs that use X.
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In addition to eliminating the variable and the statement which assigns
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a value to the variable, we may be able to later thread the jump without
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adding insane complexity in the dominator optimizer.
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Also note these transformations can cascade. We handle this by having
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a worklist of COND_EXPR statements to examine. As we make a change to
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a statement, we put it back on the worklist to examine on the next
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iteration of the main loop.
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A second class of propagation opportunities arises for ADDR_EXPR
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nodes.
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ptr = &x->y->z;
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res = *ptr;
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Will get turned into
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res = x->y->z;
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Or
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ptr = &x[0];
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ptr2 = ptr + <constant>;
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Will get turned into
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ptr2 = &x[constant/elementsize];
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Or
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ptr = &x[0];
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offset = index * element_size;
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offset_p = (pointer) offset;
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ptr2 = ptr + offset_p
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Will get turned into:
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ptr2 = &x[index];
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We also propagate casts into SWITCH_EXPR and COND_EXPR conditions to
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allow us to remove the cast and {NOT_EXPR,NEG_EXPR} into a subsequent
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{NOT_EXPR,NEG_EXPR}.
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This will (of course) be extended as other needs arise. */
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static bool forward_propagate_addr_expr (tree name, tree rhs);
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/* Set to true if we delete EH edges during the optimization. */
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static bool cfg_changed;
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/* Get the next statement we can propagate NAME's value into skipping
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trivial copies. Returns the statement that is suitable as a
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propagation destination or NULL_TREE if there is no such one.
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This only returns destinations in a single-use chain. FINAL_NAME_P
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if non-NULL is written to the ssa name that represents the use. */
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static tree
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get_prop_dest_stmt (tree name, tree *final_name_p)
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{
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use_operand_p use;
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tree use_stmt;
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do {
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/* If name has multiple uses, bail out. */
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if (!single_imm_use (name, &use, &use_stmt))
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return NULL_TREE;
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/* If this is not a trivial copy, we found it. */
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if (TREE_CODE (use_stmt) != GIMPLE_MODIFY_STMT
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|| TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 0)) != SSA_NAME
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|| GIMPLE_STMT_OPERAND (use_stmt, 1) != name)
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break;
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/* Continue searching uses of the copy destination. */
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name = GIMPLE_STMT_OPERAND (use_stmt, 0);
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} while (1);
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if (final_name_p)
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*final_name_p = name;
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return use_stmt;
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}
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/* Get the statement we can propagate from into NAME skipping
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trivial copies. Returns the statement which defines the
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propagation source or NULL_TREE if there is no such one.
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If SINGLE_USE_ONLY is set considers only sources which have
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a single use chain up to NAME. If SINGLE_USE_P is non-null,
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it is set to whether the chain to NAME is a single use chain
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or not. SINGLE_USE_P is not written to if SINGLE_USE_ONLY is set. */
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static tree
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get_prop_source_stmt (tree name, bool single_use_only, bool *single_use_p)
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{
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bool single_use = true;
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do {
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tree def_stmt = SSA_NAME_DEF_STMT (name);
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if (!has_single_use (name))
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{
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single_use = false;
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if (single_use_only)
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return NULL_TREE;
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}
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/* If name is defined by a PHI node or is the default def, bail out. */
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if (TREE_CODE (def_stmt) != GIMPLE_MODIFY_STMT)
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return NULL_TREE;
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/* If name is not a simple copy destination, we found it. */
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if (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) != SSA_NAME)
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{
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if (!single_use_only && single_use_p)
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*single_use_p = single_use;
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return def_stmt;
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}
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/* Continue searching the def of the copy source name. */
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name = GIMPLE_STMT_OPERAND (def_stmt, 1);
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} while (1);
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}
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/* Checks if the destination ssa name in DEF_STMT can be used as
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propagation source. Returns true if so, otherwise false. */
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static bool
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can_propagate_from (tree def_stmt)
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{
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tree rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
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/* We cannot propagate ssa names that occur in abnormal phi nodes. */
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switch (TREE_CODE_LENGTH (TREE_CODE (rhs)))
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{
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case 3:
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if (TREE_OPERAND (rhs, 2) != NULL_TREE
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&& TREE_CODE (TREE_OPERAND (rhs, 2)) == SSA_NAME
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (rhs, 2)))
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return false;
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case 2:
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if (TREE_OPERAND (rhs, 1) != NULL_TREE
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&& TREE_CODE (TREE_OPERAND (rhs, 1)) == SSA_NAME
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (rhs, 1)))
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return false;
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case 1:
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if (TREE_OPERAND (rhs, 0) != NULL_TREE
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&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
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&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (rhs, 0)))
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return false;
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break;
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default:
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return false;
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}
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/* If the definition is a conversion of a pointer to a function type,
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then we can not apply optimizations as some targets require function
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pointers to be canonicalized and in this case this optimization could
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eliminate a necessary canonicalization. */
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if ((TREE_CODE (rhs) == NOP_EXPR
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|| TREE_CODE (rhs) == CONVERT_EXPR)
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&& POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))
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&& TREE_CODE (TREE_TYPE (TREE_TYPE
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(TREE_OPERAND (rhs, 0)))) == FUNCTION_TYPE)
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return false;
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return true;
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}
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/* Remove a copy chain ending in NAME along the defs but not
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further or including UP_TO_STMT. If NAME was replaced in
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its only use then this function can be used to clean up
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dead stmts. Returns true if UP_TO_STMT can be removed
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as well, otherwise false. */
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static bool
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remove_prop_source_from_use (tree name, tree up_to_stmt)
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{
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block_stmt_iterator bsi;
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tree stmt;
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do {
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if (!has_zero_uses (name))
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return false;
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stmt = SSA_NAME_DEF_STMT (name);
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if (stmt == up_to_stmt)
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return true;
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bsi = bsi_for_stmt (stmt);
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release_defs (stmt);
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bsi_remove (&bsi, true);
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name = GIMPLE_STMT_OPERAND (stmt, 1);
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} while (TREE_CODE (name) == SSA_NAME);
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return false;
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}
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/* Combine OP0 CODE OP1 in the context of a COND_EXPR. Returns
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the folded result in a form suitable for COND_EXPR_COND or
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NULL_TREE, if there is no suitable simplified form. If
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INVARIANT_ONLY is true only gimple_min_invariant results are
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considered simplified. */
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static tree
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combine_cond_expr_cond (enum tree_code code, tree type,
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tree op0, tree op1, bool invariant_only)
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{
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tree t;
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gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison);
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t = fold_binary (code, type, op0, op1);
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if (!t)
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return NULL_TREE;
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/* Require that we got a boolean type out if we put one in. */
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gcc_assert (TREE_CODE (TREE_TYPE (t)) == TREE_CODE (type));
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/* For (bool)x use x != 0. */
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if (TREE_CODE (t) == NOP_EXPR
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&& TREE_TYPE (t) == boolean_type_node)
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{
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tree top0 = TREE_OPERAND (t, 0);
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t = build2 (NE_EXPR, type,
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top0, build_int_cst (TREE_TYPE (top0), 0));
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}
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/* For !x use x == 0. */
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else if (TREE_CODE (t) == TRUTH_NOT_EXPR)
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{
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tree top0 = TREE_OPERAND (t, 0);
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t = build2 (EQ_EXPR, type,
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top0, build_int_cst (TREE_TYPE (top0), 0));
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}
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/* For cmp ? 1 : 0 use cmp. */
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else if (TREE_CODE (t) == COND_EXPR
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&& COMPARISON_CLASS_P (TREE_OPERAND (t, 0))
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&& integer_onep (TREE_OPERAND (t, 1))
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&& integer_zerop (TREE_OPERAND (t, 2)))
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{
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tree top0 = TREE_OPERAND (t, 0);
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t = build2 (TREE_CODE (top0), type,
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TREE_OPERAND (top0, 0), TREE_OPERAND (top0, 1));
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}
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/* Bail out if we required an invariant but didn't get one. */
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if (invariant_only
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&& !is_gimple_min_invariant (t))
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return NULL_TREE;
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/* A valid conditional for a COND_EXPR is either a gimple value
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or a comparison with two gimple value operands. */
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if (is_gimple_val (t)
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|| (COMPARISON_CLASS_P (t)
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&& is_gimple_val (TREE_OPERAND (t, 0))
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&& is_gimple_val (TREE_OPERAND (t, 1))))
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return t;
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return NULL_TREE;
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}
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/* Propagate from the ssa name definition statements of COND_EXPR
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in statement STMT into the conditional if that simplifies it.
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Returns zero if no statement was changed, one if there were
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changes and two if cfg_cleanup needs to run. */
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static int
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forward_propagate_into_cond (tree cond_expr, tree stmt)
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{
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int did_something = 0;
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do {
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tree tmp = NULL_TREE;
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tree cond = COND_EXPR_COND (cond_expr);
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tree name, def_stmt, rhs;
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bool single_use_p;
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/* We can do tree combining on SSA_NAME and comparison expressions. */
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if (COMPARISON_CLASS_P (cond)
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&& TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME)
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{
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/* For comparisons use the first operand, that is likely to
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simplify comparisons against constants. */
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name = TREE_OPERAND (cond, 0);
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def_stmt = get_prop_source_stmt (name, false, &single_use_p);
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if (def_stmt != NULL_TREE
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&& can_propagate_from (def_stmt))
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{
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tree op1 = TREE_OPERAND (cond, 1);
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rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
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tmp = combine_cond_expr_cond (TREE_CODE (cond), boolean_type_node,
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fold_convert (TREE_TYPE (op1), rhs),
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op1, !single_use_p);
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}
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/* If that wasn't successful, try the second operand. */
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if (tmp == NULL_TREE
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&& TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME)
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{
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tree op0 = TREE_OPERAND (cond, 0);
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name = TREE_OPERAND (cond, 1);
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def_stmt = get_prop_source_stmt (name, false, &single_use_p);
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if (def_stmt == NULL_TREE
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|| !can_propagate_from (def_stmt))
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return did_something;
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rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
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tmp = combine_cond_expr_cond (TREE_CODE (cond), boolean_type_node,
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op0,
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fold_convert (TREE_TYPE (op0), rhs),
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!single_use_p);
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}
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}
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else if (TREE_CODE (cond) == SSA_NAME)
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{
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name = cond;
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def_stmt = get_prop_source_stmt (name, true, NULL);
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if (def_stmt == NULL_TREE
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|| !can_propagate_from (def_stmt))
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return did_something;
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rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
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tmp = combine_cond_expr_cond (NE_EXPR, boolean_type_node, rhs,
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build_int_cst (TREE_TYPE (rhs), 0),
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false);
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}
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if (tmp)
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{
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if (dump_file && tmp)
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{
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fprintf (dump_file, " Replaced '");
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print_generic_expr (dump_file, cond, 0);
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fprintf (dump_file, "' with '");
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print_generic_expr (dump_file, tmp, 0);
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fprintf (dump_file, "'\n");
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}
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COND_EXPR_COND (cond_expr) = unshare_expr (tmp);
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update_stmt (stmt);
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/* Remove defining statements. */
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remove_prop_source_from_use (name, NULL);
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if (is_gimple_min_invariant (tmp))
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did_something = 2;
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else if (did_something == 0)
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did_something = 1;
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/* Continue combining. */
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continue;
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}
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break;
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} while (1);
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return did_something;
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}
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/* We've just substituted an ADDR_EXPR into stmt. Update all the
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relevant data structures to match. */
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static void
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tidy_after_forward_propagate_addr (tree stmt)
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{
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/* We may have turned a trapping insn into a non-trapping insn. */
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if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
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&& tree_purge_dead_eh_edges (bb_for_stmt (stmt)))
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cfg_changed = true;
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if (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ADDR_EXPR)
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recompute_tree_invariant_for_addr_expr (GIMPLE_STMT_OPERAND (stmt, 1));
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mark_symbols_for_renaming (stmt);
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}
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/* DEF_RHS contains the address of the 0th element in an array.
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USE_STMT uses type of DEF_RHS to compute the address of an
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arbitrary element within the array. The (variable) byte offset
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of the element is contained in OFFSET.
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We walk back through the use-def chains of OFFSET to verify that
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it is indeed computing the offset of an element within the array
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and extract the index corresponding to the given byte offset.
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We then try to fold the entire address expression into a form
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&array[index].
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If we are successful, we replace the right hand side of USE_STMT
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with the new address computation. */
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|
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static bool
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forward_propagate_addr_into_variable_array_index (tree offset,
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tree def_rhs, tree use_stmt)
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{
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tree index;
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|
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/* Try to find an expression for a proper index. This is either
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a multiplication expression by the element size or just the
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ssa name we came along in case the element size is one. */
|
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if (integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)))))
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index = offset;
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else
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{
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/* Get the offset's defining statement. */
|
|
offset = SSA_NAME_DEF_STMT (offset);
|
|
|
|
/* The statement which defines OFFSET before type conversion
|
|
must be a simple GIMPLE_MODIFY_STMT. */
|
|
if (TREE_CODE (offset) != GIMPLE_MODIFY_STMT)
|
|
return false;
|
|
|
|
/* The RHS of the statement which defines OFFSET must be a
|
|
multiplication of an object by the size of the array elements.
|
|
This implicitly verifies that the size of the array elements
|
|
is constant. */
|
|
offset = GIMPLE_STMT_OPERAND (offset, 1);
|
|
if (TREE_CODE (offset) != MULT_EXPR
|
|
|| TREE_CODE (TREE_OPERAND (offset, 1)) != INTEGER_CST
|
|
|| !simple_cst_equal (TREE_OPERAND (offset, 1),
|
|
TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)))))
|
|
return false;
|
|
|
|
/* The first operand to the MULT_EXPR is the desired index. */
|
|
index = TREE_OPERAND (offset, 0);
|
|
}
|
|
|
|
/* Replace the pointer addition with array indexing. */
|
|
GIMPLE_STMT_OPERAND (use_stmt, 1) = unshare_expr (def_rhs);
|
|
TREE_OPERAND (TREE_OPERAND (GIMPLE_STMT_OPERAND (use_stmt, 1), 0), 1)
|
|
= index;
|
|
|
|
/* That should have created gimple, so there is no need to
|
|
record information to undo the propagation. */
|
|
fold_stmt_inplace (use_stmt);
|
|
tidy_after_forward_propagate_addr (use_stmt);
|
|
return true;
|
|
}
|
|
|
|
/* NAME is a SSA_NAME representing DEF_RHS which is of the form
|
|
ADDR_EXPR <whatever>.
|
|
|
|
Try to forward propagate the ADDR_EXPR into the use USE_STMT.
|
|
Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
|
|
node or for recovery of array indexing from pointer arithmetic.
|
|
|
|
Return true if the propagation was successful (the propagation can
|
|
be not totally successful, yet things may have been changed). */
|
|
|
|
static bool
|
|
forward_propagate_addr_expr_1 (tree name, tree def_rhs, tree use_stmt,
|
|
bool single_use_p)
|
|
{
|
|
tree lhs, rhs, array_ref;
|
|
|
|
/* Strip away any outer COMPONENT_REF/ARRAY_REF nodes from the LHS.
|
|
ADDR_EXPR will not appear on the LHS. */
|
|
lhs = GIMPLE_STMT_OPERAND (use_stmt, 0);
|
|
while (handled_component_p (lhs))
|
|
lhs = TREE_OPERAND (lhs, 0);
|
|
|
|
rhs = GIMPLE_STMT_OPERAND (use_stmt, 1);
|
|
|
|
/* Now see if the LHS node is an INDIRECT_REF using NAME. If so,
|
|
propagate the ADDR_EXPR into the use of NAME and fold the result. */
|
|
if (TREE_CODE (lhs) == INDIRECT_REF && TREE_OPERAND (lhs, 0) == name)
|
|
{
|
|
/* This should always succeed in creating gimple, so there is
|
|
no need to save enough state to undo this propagation. */
|
|
TREE_OPERAND (lhs, 0) = unshare_expr (def_rhs);
|
|
fold_stmt_inplace (use_stmt);
|
|
tidy_after_forward_propagate_addr (use_stmt);
|
|
|
|
/* Continue propagating into the RHS. */
|
|
}
|
|
|
|
/* Trivial cases. The use statement could be a trivial copy or a
|
|
useless conversion. Recurse to the uses of the lhs as copyprop does
|
|
not copy through differen variant pointers and FRE does not catch
|
|
all useless conversions. Treat the case of a single-use name and
|
|
a conversion to def_rhs type separate, though. */
|
|
else if (TREE_CODE (lhs) == SSA_NAME
|
|
&& (TREE_CODE (rhs) == NOP_EXPR
|
|
|| TREE_CODE (rhs) == CONVERT_EXPR)
|
|
&& TREE_TYPE (rhs) == TREE_TYPE (def_rhs)
|
|
&& single_use_p)
|
|
{
|
|
GIMPLE_STMT_OPERAND (use_stmt, 1) = unshare_expr (def_rhs);
|
|
return true;
|
|
}
|
|
else if ((TREE_CODE (lhs) == SSA_NAME
|
|
&& rhs == name)
|
|
|| ((TREE_CODE (rhs) == NOP_EXPR
|
|
|| TREE_CODE (rhs) == CONVERT_EXPR)
|
|
&& useless_type_conversion_p (TREE_TYPE (rhs),
|
|
TREE_TYPE (def_rhs))))
|
|
return forward_propagate_addr_expr (lhs, def_rhs);
|
|
|
|
/* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
|
|
nodes from the RHS. */
|
|
while (handled_component_p (rhs)
|
|
|| TREE_CODE (rhs) == ADDR_EXPR)
|
|
rhs = TREE_OPERAND (rhs, 0);
|
|
|
|
/* Now see if the RHS node is an INDIRECT_REF using NAME. If so,
|
|
propagate the ADDR_EXPR into the use of NAME and fold the result. */
|
|
if (TREE_CODE (rhs) == INDIRECT_REF && TREE_OPERAND (rhs, 0) == name)
|
|
{
|
|
/* This should always succeed in creating gimple, so there is
|
|
no need to save enough state to undo this propagation. */
|
|
TREE_OPERAND (rhs, 0) = unshare_expr (def_rhs);
|
|
fold_stmt_inplace (use_stmt);
|
|
tidy_after_forward_propagate_addr (use_stmt);
|
|
return true;
|
|
}
|
|
|
|
/* The remaining cases are all for turning pointer arithmetic into
|
|
array indexing. They only apply when we have the address of
|
|
element zero in an array. If that is not the case then there
|
|
is nothing to do. */
|
|
array_ref = TREE_OPERAND (def_rhs, 0);
|
|
if (TREE_CODE (array_ref) != ARRAY_REF
|
|
|| TREE_CODE (TREE_TYPE (TREE_OPERAND (array_ref, 0))) != ARRAY_TYPE
|
|
|| !integer_zerop (TREE_OPERAND (array_ref, 1)))
|
|
return false;
|
|
|
|
/* If the use of the ADDR_EXPR is not a POINTER_PLUS_EXPR, there
|
|
is nothing to do. */
|
|
if (TREE_CODE (rhs) != POINTER_PLUS_EXPR)
|
|
return false;
|
|
|
|
/* Try to optimize &x[0] p+ C where C is a multiple of the size
|
|
of the elements in X into &x[C/element size]. */
|
|
if (TREE_OPERAND (rhs, 0) == name
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST)
|
|
{
|
|
tree orig = unshare_expr (rhs);
|
|
TREE_OPERAND (rhs, 0) = unshare_expr (def_rhs);
|
|
|
|
/* If folding succeeds, then we have just exposed new variables
|
|
in USE_STMT which will need to be renamed. If folding fails,
|
|
then we need to put everything back the way it was. */
|
|
if (fold_stmt_inplace (use_stmt))
|
|
{
|
|
tidy_after_forward_propagate_addr (use_stmt);
|
|
return true;
|
|
}
|
|
else
|
|
{
|
|
GIMPLE_STMT_OPERAND (use_stmt, 1) = orig;
|
|
update_stmt (use_stmt);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* Try to optimize &x[0] p+ OFFSET where OFFSET is defined by
|
|
converting a multiplication of an index by the size of the
|
|
array elements, then the result is converted into the proper
|
|
type for the arithmetic. */
|
|
if (TREE_OPERAND (rhs, 0) == name
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 1)) == SSA_NAME
|
|
/* Avoid problems with IVopts creating PLUS_EXPRs with a
|
|
different type than their operands. */
|
|
&& useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (name)))
|
|
{
|
|
bool res;
|
|
|
|
res = forward_propagate_addr_into_variable_array_index (TREE_OPERAND (rhs, 1),
|
|
def_rhs, use_stmt);
|
|
return res;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/* STMT is a statement of the form SSA_NAME = ADDR_EXPR <whatever>.
|
|
|
|
Try to forward propagate the ADDR_EXPR into all uses of the SSA_NAME.
|
|
Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
|
|
node or for recovery of array indexing from pointer arithmetic.
|
|
Returns true, if all uses have been propagated into. */
|
|
|
|
static bool
|
|
forward_propagate_addr_expr (tree name, tree rhs)
|
|
{
|
|
int stmt_loop_depth = bb_for_stmt (SSA_NAME_DEF_STMT (name))->loop_depth;
|
|
imm_use_iterator iter;
|
|
tree use_stmt;
|
|
bool all = true;
|
|
bool single_use_p = has_single_use (name);
|
|
|
|
FOR_EACH_IMM_USE_STMT (use_stmt, iter, name)
|
|
{
|
|
bool result;
|
|
|
|
/* If the use is not in a simple assignment statement, then
|
|
there is nothing we can do. */
|
|
if (TREE_CODE (use_stmt) != GIMPLE_MODIFY_STMT)
|
|
{
|
|
all = false;
|
|
continue;
|
|
}
|
|
|
|
/* If the use is in a deeper loop nest, then we do not want
|
|
to propagate the ADDR_EXPR into the loop as that is likely
|
|
adding expression evaluations into the loop. */
|
|
if (bb_for_stmt (use_stmt)->loop_depth > stmt_loop_depth)
|
|
{
|
|
all = false;
|
|
continue;
|
|
}
|
|
|
|
push_stmt_changes (&use_stmt);
|
|
|
|
result = forward_propagate_addr_expr_1 (name, rhs, use_stmt,
|
|
single_use_p);
|
|
all &= result;
|
|
|
|
pop_stmt_changes (&use_stmt);
|
|
|
|
/* Remove intermediate now unused copy and conversion chains. */
|
|
if (result
|
|
&& TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 0)) == SSA_NAME
|
|
&& (TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == SSA_NAME
|
|
|| TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == NOP_EXPR
|
|
|| TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == CONVERT_EXPR))
|
|
{
|
|
block_stmt_iterator bsi = bsi_for_stmt (use_stmt);
|
|
release_defs (use_stmt);
|
|
bsi_remove (&bsi, true);
|
|
}
|
|
}
|
|
|
|
return all;
|
|
}
|
|
|
|
/* Forward propagate the comparison COND defined in STMT like
|
|
cond_1 = x CMP y to uses of the form
|
|
a_1 = (T')cond_1
|
|
a_1 = !cond_1
|
|
a_1 = cond_1 != 0
|
|
Returns true if stmt is now unused. */
|
|
|
|
static bool
|
|
forward_propagate_comparison (tree cond, tree stmt)
|
|
{
|
|
tree name = GIMPLE_STMT_OPERAND (stmt, 0);
|
|
tree use_stmt, tmp = NULL_TREE;
|
|
|
|
/* Don't propagate ssa names that occur in abnormal phis. */
|
|
if ((TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
|
|
&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (cond, 0)))
|
|
|| (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME
|
|
&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (cond, 1))))
|
|
return false;
|
|
|
|
/* Do not un-cse comparisons. But propagate through copies. */
|
|
use_stmt = get_prop_dest_stmt (name, &name);
|
|
if (use_stmt == NULL_TREE)
|
|
return false;
|
|
|
|
/* Conversion of the condition result to another integral type. */
|
|
if (TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
|
|
&& (TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == CONVERT_EXPR
|
|
|| TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == NOP_EXPR
|
|
|| COMPARISON_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1))
|
|
|| TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == TRUTH_NOT_EXPR)
|
|
&& INTEGRAL_TYPE_P (TREE_TYPE (GIMPLE_STMT_OPERAND (use_stmt, 0))))
|
|
{
|
|
tree lhs = GIMPLE_STMT_OPERAND (use_stmt, 0);
|
|
tree rhs = GIMPLE_STMT_OPERAND (use_stmt, 1);
|
|
|
|
/* We can propagate the condition into a conversion. */
|
|
if (TREE_CODE (rhs) == CONVERT_EXPR
|
|
|| TREE_CODE (rhs) == NOP_EXPR)
|
|
{
|
|
/* Avoid using fold here as that may create a COND_EXPR with
|
|
non-boolean condition as canonical form. */
|
|
tmp = build2 (TREE_CODE (cond), TREE_TYPE (lhs),
|
|
TREE_OPERAND (cond, 0), TREE_OPERAND (cond, 1));
|
|
}
|
|
/* We can propagate the condition into X op CST where op
|
|
is EQ_EXRP or NE_EXPR and CST is either one or zero. */
|
|
else if (COMPARISON_CLASS_P (rhs)
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST)
|
|
{
|
|
enum tree_code code = TREE_CODE (rhs);
|
|
tree cst = TREE_OPERAND (rhs, 1);
|
|
|
|
tmp = combine_cond_expr_cond (code, TREE_TYPE (lhs),
|
|
fold_convert (TREE_TYPE (cst), cond),
|
|
cst, false);
|
|
if (tmp == NULL_TREE)
|
|
return false;
|
|
}
|
|
/* We can propagate the condition into a statement that
|
|
computes the logical negation of the comparison result. */
|
|
else if (TREE_CODE (rhs) == TRUTH_NOT_EXPR)
|
|
{
|
|
tree type = TREE_TYPE (TREE_OPERAND (cond, 0));
|
|
bool nans = HONOR_NANS (TYPE_MODE (type));
|
|
enum tree_code code;
|
|
code = invert_tree_comparison (TREE_CODE (cond), nans);
|
|
if (code == ERROR_MARK)
|
|
return false;
|
|
|
|
tmp = build2 (code, TREE_TYPE (lhs), TREE_OPERAND (cond, 0),
|
|
TREE_OPERAND (cond, 1));
|
|
}
|
|
else
|
|
return false;
|
|
|
|
GIMPLE_STMT_OPERAND (use_stmt, 1) = unshare_expr (tmp);
|
|
update_stmt (use_stmt);
|
|
|
|
/* Remove defining statements. */
|
|
remove_prop_source_from_use (name, stmt);
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
fprintf (dump_file, " Replaced '");
|
|
print_generic_expr (dump_file, rhs, dump_flags);
|
|
fprintf (dump_file, "' with '");
|
|
print_generic_expr (dump_file, tmp, dump_flags);
|
|
fprintf (dump_file, "'\n");
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/* If we have lhs = ~x (STMT), look and see if earlier we had x = ~y.
|
|
If so, we can change STMT into lhs = y which can later be copy
|
|
propagated. Similarly for negation.
|
|
|
|
This could trivially be formulated as a forward propagation
|
|
to immediate uses. However, we already had an implementation
|
|
from DOM which used backward propagation via the use-def links.
|
|
|
|
It turns out that backward propagation is actually faster as
|
|
there's less work to do for each NOT/NEG expression we find.
|
|
Backwards propagation needs to look at the statement in a single
|
|
backlink. Forward propagation needs to look at potentially more
|
|
than one forward link. */
|
|
|
|
static void
|
|
simplify_not_neg_expr (tree stmt)
|
|
{
|
|
tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
|
|
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
|
|
|
|
/* See if the RHS_DEF_STMT has the same form as our statement. */
|
|
if (TREE_CODE (rhs_def_stmt) == GIMPLE_MODIFY_STMT
|
|
&& TREE_CODE (GIMPLE_STMT_OPERAND (rhs_def_stmt, 1)) == TREE_CODE (rhs))
|
|
{
|
|
tree rhs_def_operand =
|
|
TREE_OPERAND (GIMPLE_STMT_OPERAND (rhs_def_stmt, 1), 0);
|
|
|
|
/* Verify that RHS_DEF_OPERAND is a suitable SSA_NAME. */
|
|
if (TREE_CODE (rhs_def_operand) == SSA_NAME
|
|
&& ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
|
|
{
|
|
GIMPLE_STMT_OPERAND (stmt, 1) = rhs_def_operand;
|
|
update_stmt (stmt);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* STMT is a SWITCH_EXPR for which we attempt to find equivalent forms of
|
|
the condition which we may be able to optimize better. */
|
|
|
|
static void
|
|
simplify_switch_expr (tree stmt)
|
|
{
|
|
tree cond = SWITCH_COND (stmt);
|
|
tree def, to, ti;
|
|
|
|
/* The optimization that we really care about is removing unnecessary
|
|
casts. That will let us do much better in propagating the inferred
|
|
constant at the switch target. */
|
|
if (TREE_CODE (cond) == SSA_NAME)
|
|
{
|
|
def = SSA_NAME_DEF_STMT (cond);
|
|
if (TREE_CODE (def) == GIMPLE_MODIFY_STMT)
|
|
{
|
|
def = GIMPLE_STMT_OPERAND (def, 1);
|
|
if (TREE_CODE (def) == NOP_EXPR)
|
|
{
|
|
int need_precision;
|
|
bool fail;
|
|
|
|
def = TREE_OPERAND (def, 0);
|
|
|
|
#ifdef ENABLE_CHECKING
|
|
/* ??? Why was Jeff testing this? We are gimple... */
|
|
gcc_assert (is_gimple_val (def));
|
|
#endif
|
|
|
|
to = TREE_TYPE (cond);
|
|
ti = TREE_TYPE (def);
|
|
|
|
/* If we have an extension that preserves value, then we
|
|
can copy the source value into the switch. */
|
|
|
|
need_precision = TYPE_PRECISION (ti);
|
|
fail = false;
|
|
if (! INTEGRAL_TYPE_P (ti))
|
|
fail = true;
|
|
else if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
|
|
fail = true;
|
|
else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
|
|
need_precision += 1;
|
|
if (TYPE_PRECISION (to) < need_precision)
|
|
fail = true;
|
|
|
|
if (!fail)
|
|
{
|
|
SWITCH_COND (stmt) = def;
|
|
update_stmt (stmt);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Main entry point for the forward propagation optimizer. */
|
|
|
|
static unsigned int
|
|
tree_ssa_forward_propagate_single_use_vars (void)
|
|
{
|
|
basic_block bb;
|
|
unsigned int todoflags = 0;
|
|
|
|
cfg_changed = false;
|
|
|
|
FOR_EACH_BB (bb)
|
|
{
|
|
block_stmt_iterator bsi;
|
|
|
|
/* Note we update BSI within the loop as necessary. */
|
|
for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
|
|
{
|
|
tree stmt = bsi_stmt (bsi);
|
|
|
|
/* If this statement sets an SSA_NAME to an address,
|
|
try to propagate the address into the uses of the SSA_NAME. */
|
|
if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
|
|
{
|
|
tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
|
|
tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
|
|
|
|
|
|
if (TREE_CODE (lhs) != SSA_NAME)
|
|
{
|
|
bsi_next (&bsi);
|
|
continue;
|
|
}
|
|
|
|
if (TREE_CODE (rhs) == ADDR_EXPR)
|
|
{
|
|
if (forward_propagate_addr_expr (lhs, rhs))
|
|
{
|
|
release_defs (stmt);
|
|
todoflags |= TODO_remove_unused_locals;
|
|
bsi_remove (&bsi, true);
|
|
}
|
|
else
|
|
bsi_next (&bsi);
|
|
}
|
|
else if ((TREE_CODE (rhs) == BIT_NOT_EXPR
|
|
|| TREE_CODE (rhs) == NEGATE_EXPR)
|
|
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
|
|
{
|
|
simplify_not_neg_expr (stmt);
|
|
bsi_next (&bsi);
|
|
}
|
|
else if (TREE_CODE (rhs) == COND_EXPR)
|
|
{
|
|
int did_something;
|
|
fold_defer_overflow_warnings ();
|
|
did_something = forward_propagate_into_cond (rhs, stmt);
|
|
if (did_something == 2)
|
|
cfg_changed = true;
|
|
fold_undefer_overflow_warnings (!TREE_NO_WARNING (rhs)
|
|
&& did_something, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL);
|
|
bsi_next (&bsi);
|
|
}
|
|
else if (COMPARISON_CLASS_P (rhs))
|
|
{
|
|
if (forward_propagate_comparison (rhs, stmt))
|
|
{
|
|
release_defs (stmt);
|
|
todoflags |= TODO_remove_unused_locals;
|
|
bsi_remove (&bsi, true);
|
|
}
|
|
else
|
|
bsi_next (&bsi);
|
|
}
|
|
else
|
|
bsi_next (&bsi);
|
|
}
|
|
else if (TREE_CODE (stmt) == SWITCH_EXPR)
|
|
{
|
|
simplify_switch_expr (stmt);
|
|
bsi_next (&bsi);
|
|
}
|
|
else if (TREE_CODE (stmt) == COND_EXPR)
|
|
{
|
|
int did_something;
|
|
fold_defer_overflow_warnings ();
|
|
did_something = forward_propagate_into_cond (stmt, stmt);
|
|
if (did_something == 2)
|
|
cfg_changed = true;
|
|
fold_undefer_overflow_warnings (!TREE_NO_WARNING (stmt)
|
|
&& did_something, stmt,
|
|
WARN_STRICT_OVERFLOW_CONDITIONAL);
|
|
bsi_next (&bsi);
|
|
}
|
|
else
|
|
bsi_next (&bsi);
|
|
}
|
|
}
|
|
|
|
if (cfg_changed)
|
|
todoflags |= TODO_cleanup_cfg;
|
|
return todoflags;
|
|
}
|
|
|
|
|
|
static bool
|
|
gate_forwprop (void)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
struct tree_opt_pass pass_forwprop = {
|
|
"forwprop", /* name */
|
|
gate_forwprop, /* gate */
|
|
tree_ssa_forward_propagate_single_use_vars, /* execute */
|
|
NULL, /* sub */
|
|
NULL, /* next */
|
|
0, /* static_pass_number */
|
|
TV_TREE_FORWPROP, /* tv_id */
|
|
PROP_cfg | PROP_ssa, /* properties_required */
|
|
0, /* properties_provided */
|
|
0, /* properties_destroyed */
|
|
0, /* todo_flags_start */
|
|
TODO_dump_func
|
|
| TODO_ggc_collect
|
|
| TODO_update_ssa
|
|
| TODO_verify_ssa, /* todo_flags_finish */
|
|
0 /* letter */
|
|
};
|
|
|
|
|
|
/* Structure to keep track of the value of a dereferenced PHI result
|
|
and the set of virtual operands used for that dereference. */
|
|
|
|
struct phiprop_d
|
|
{
|
|
tree value;
|
|
tree vop_stmt;
|
|
};
|
|
|
|
/* Verify if the value recorded for NAME in PHIVN is still valid at
|
|
the start of basic block BB. */
|
|
|
|
static bool
|
|
phivn_valid_p (struct phiprop_d *phivn, tree name, basic_block bb)
|
|
{
|
|
tree vop_stmt = phivn[SSA_NAME_VERSION (name)].vop_stmt;
|
|
ssa_op_iter ui;
|
|
tree vuse;
|
|
|
|
/* The def stmts of all virtual uses need to be post-dominated
|
|
by bb. */
|
|
FOR_EACH_SSA_TREE_OPERAND (vuse, vop_stmt, ui, SSA_OP_VUSE)
|
|
{
|
|
tree use_stmt;
|
|
imm_use_iterator ui2;
|
|
bool ok = true;
|
|
|
|
FOR_EACH_IMM_USE_STMT (use_stmt, ui2, vuse)
|
|
{
|
|
/* If BB does not dominate a VDEF, the value is invalid. */
|
|
if (((TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
|
|
&& !ZERO_SSA_OPERANDS (use_stmt, SSA_OP_VDEF))
|
|
|| TREE_CODE (use_stmt) == PHI_NODE)
|
|
&& !dominated_by_p (CDI_DOMINATORS, bb_for_stmt (use_stmt), bb))
|
|
{
|
|
ok = false;
|
|
BREAK_FROM_IMM_USE_STMT (ui2);
|
|
}
|
|
}
|
|
if (!ok)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Insert a new phi node for the dereference of PHI at basic_block
|
|
BB with the virtual operands from USE_STMT. */
|
|
|
|
static tree
|
|
phiprop_insert_phi (basic_block bb, tree phi, tree use_stmt,
|
|
struct phiprop_d *phivn, size_t n)
|
|
{
|
|
tree res, new_phi;
|
|
edge_iterator ei;
|
|
edge e;
|
|
|
|
/* Build a new PHI node to replace the definition of
|
|
the indirect reference lhs. */
|
|
res = GIMPLE_STMT_OPERAND (use_stmt, 0);
|
|
SSA_NAME_DEF_STMT (res) = new_phi = create_phi_node (res, bb);
|
|
|
|
/* Add PHI arguments for each edge inserting loads of the
|
|
addressable operands. */
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
|
{
|
|
tree old_arg, new_var, tmp;
|
|
|
|
old_arg = PHI_ARG_DEF_FROM_EDGE (phi, e);
|
|
while (TREE_CODE (old_arg) == SSA_NAME
|
|
&& (SSA_NAME_VERSION (old_arg) >= n
|
|
|| phivn[SSA_NAME_VERSION (old_arg)].value == NULL_TREE))
|
|
{
|
|
tree def_stmt = SSA_NAME_DEF_STMT (old_arg);
|
|
old_arg = GIMPLE_STMT_OPERAND (def_stmt, 1);
|
|
}
|
|
|
|
if (TREE_CODE (old_arg) == SSA_NAME)
|
|
/* Reuse a formerly created dereference. */
|
|
new_var = phivn[SSA_NAME_VERSION (old_arg)].value;
|
|
else
|
|
{
|
|
old_arg = TREE_OPERAND (old_arg, 0);
|
|
new_var = create_tmp_var (TREE_TYPE (old_arg), NULL);
|
|
tmp = build2 (GIMPLE_MODIFY_STMT, void_type_node,
|
|
NULL_TREE, unshare_expr (old_arg));
|
|
if (TREE_CODE (TREE_TYPE (old_arg)) == COMPLEX_TYPE
|
|
|| TREE_CODE (TREE_TYPE (old_arg)) == VECTOR_TYPE)
|
|
DECL_GIMPLE_REG_P (new_var) = 1;
|
|
add_referenced_var (new_var);
|
|
new_var = make_ssa_name (new_var, tmp);
|
|
GIMPLE_STMT_OPERAND (tmp, 0) = new_var;
|
|
|
|
bsi_insert_on_edge (e, tmp);
|
|
|
|
update_stmt (tmp);
|
|
mark_symbols_for_renaming (tmp);
|
|
}
|
|
|
|
add_phi_arg (new_phi, new_var, e);
|
|
}
|
|
|
|
update_stmt (new_phi);
|
|
|
|
return res;
|
|
}
|
|
|
|
/* Propagate between the phi node arguments of PHI in BB and phi result
|
|
users. For now this matches
|
|
# p_2 = PHI <&x, &y>
|
|
<Lx>:;
|
|
p_3 = p_2;
|
|
z_2 = *p_3;
|
|
and converts it to
|
|
# z_2 = PHI <x, y>
|
|
<Lx>:;
|
|
Returns true if a transformation was done and edge insertions
|
|
need to be committed. Global data PHIVN and N is used to track
|
|
past transformation results. We need to be especially careful here
|
|
with aliasing issues as we are moving memory reads. */
|
|
|
|
static bool
|
|
propagate_with_phi (basic_block bb, tree phi, struct phiprop_d *phivn, size_t n)
|
|
{
|
|
tree ptr = PHI_RESULT (phi);
|
|
tree use_stmt, res = NULL_TREE;
|
|
block_stmt_iterator bsi;
|
|
imm_use_iterator ui;
|
|
use_operand_p arg_p, use;
|
|
ssa_op_iter i;
|
|
bool phi_inserted;
|
|
|
|
if (MTAG_P (SSA_NAME_VAR (ptr))
|
|
|| !POINTER_TYPE_P (TREE_TYPE (ptr))
|
|
|| !is_gimple_reg_type (TREE_TYPE (TREE_TYPE (ptr))))
|
|
return false;
|
|
|
|
/* Check if we can "cheaply" dereference all phi arguments. */
|
|
FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
|
|
{
|
|
tree arg = USE_FROM_PTR (arg_p);
|
|
/* Walk the ssa chain until we reach a ssa name we already
|
|
created a value for or we reach a definition of the form
|
|
ssa_name_n = &var; */
|
|
while (TREE_CODE (arg) == SSA_NAME
|
|
&& !SSA_NAME_IS_DEFAULT_DEF (arg)
|
|
&& (SSA_NAME_VERSION (arg) >= n
|
|
|| phivn[SSA_NAME_VERSION (arg)].value == NULL_TREE))
|
|
{
|
|
tree def_stmt = SSA_NAME_DEF_STMT (arg);
|
|
if (TREE_CODE (def_stmt) != GIMPLE_MODIFY_STMT)
|
|
return false;
|
|
arg = GIMPLE_STMT_OPERAND (def_stmt, 1);
|
|
}
|
|
if ((TREE_CODE (arg) != ADDR_EXPR
|
|
/* Avoid to have to decay *&a to a[0] later. */
|
|
|| !is_gimple_reg_type (TREE_TYPE (TREE_OPERAND (arg, 0))))
|
|
&& !(TREE_CODE (arg) == SSA_NAME
|
|
&& phivn[SSA_NAME_VERSION (arg)].value != NULL_TREE
|
|
&& phivn_valid_p (phivn, arg, bb)))
|
|
return false;
|
|
}
|
|
|
|
/* Find a dereferencing use. First follow (single use) ssa
|
|
copy chains for ptr. */
|
|
while (single_imm_use (ptr, &use, &use_stmt)
|
|
&& TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
|
|
&& GIMPLE_STMT_OPERAND (use_stmt, 1) == ptr
|
|
&& TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 0)) == SSA_NAME)
|
|
ptr = GIMPLE_STMT_OPERAND (use_stmt, 0);
|
|
|
|
/* Replace the first dereference of *ptr if there is one and if we
|
|
can move the loads to the place of the ptr phi node. */
|
|
phi_inserted = false;
|
|
FOR_EACH_IMM_USE_STMT (use_stmt, ui, ptr)
|
|
{
|
|
ssa_op_iter ui2;
|
|
tree vuse;
|
|
|
|
/* Check whether this is a load of *ptr. */
|
|
if (!(TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
|
|
&& TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 0)) == SSA_NAME
|
|
&& TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == INDIRECT_REF
|
|
&& TREE_OPERAND (GIMPLE_STMT_OPERAND (use_stmt, 1), 0) == ptr
|
|
/* We cannot replace a load that may throw or is volatile. */
|
|
&& !tree_can_throw_internal (use_stmt)))
|
|
continue;
|
|
|
|
/* Check if we can move the loads. The def stmts of all virtual uses
|
|
need to be post-dominated by bb. */
|
|
FOR_EACH_SSA_TREE_OPERAND (vuse, use_stmt, ui2, SSA_OP_VUSE)
|
|
{
|
|
tree def_stmt = SSA_NAME_DEF_STMT (vuse);
|
|
if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
|
|
&& (bb_for_stmt (def_stmt) == bb
|
|
|| !dominated_by_p (CDI_DOMINATORS,
|
|
bb, bb_for_stmt (def_stmt))))
|
|
goto next;
|
|
}
|
|
|
|
/* Found a proper dereference. Insert a phi node if this
|
|
is the first load transformation. */
|
|
if (!phi_inserted)
|
|
{
|
|
res = phiprop_insert_phi (bb, phi, use_stmt, phivn, n);
|
|
|
|
/* Remember the value we created for *ptr. */
|
|
phivn[SSA_NAME_VERSION (ptr)].value = res;
|
|
phivn[SSA_NAME_VERSION (ptr)].vop_stmt = use_stmt;
|
|
|
|
/* Remove old stmt. The phi is taken care of by DCE, if we
|
|
want to delete it here we also have to delete all intermediate
|
|
copies. */
|
|
bsi = bsi_for_stmt (use_stmt);
|
|
bsi_remove (&bsi, 0);
|
|
|
|
phi_inserted = true;
|
|
}
|
|
else
|
|
{
|
|
/* Further replacements are easy, just make a copy out of the
|
|
load. */
|
|
GIMPLE_STMT_OPERAND (use_stmt, 1) = res;
|
|
update_stmt (use_stmt);
|
|
}
|
|
|
|
next:;
|
|
/* Continue searching for a proper dereference. */
|
|
}
|
|
|
|
return phi_inserted;
|
|
}
|
|
|
|
/* Helper walking the dominator tree starting from BB and processing
|
|
phi nodes with global data PHIVN and N. */
|
|
|
|
static bool
|
|
tree_ssa_phiprop_1 (basic_block bb, struct phiprop_d *phivn, size_t n)
|
|
{
|
|
bool did_something = false;
|
|
basic_block son;
|
|
tree phi;
|
|
|
|
for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
|
|
did_something |= propagate_with_phi (bb, phi, phivn, n);
|
|
|
|
for (son = first_dom_son (CDI_DOMINATORS, bb);
|
|
son;
|
|
son = next_dom_son (CDI_DOMINATORS, son))
|
|
did_something |= tree_ssa_phiprop_1 (son, phivn, n);
|
|
|
|
return did_something;
|
|
}
|
|
|
|
/* Main entry for phiprop pass. */
|
|
|
|
static unsigned int
|
|
tree_ssa_phiprop (void)
|
|
{
|
|
struct phiprop_d *phivn;
|
|
|
|
calculate_dominance_info (CDI_DOMINATORS);
|
|
|
|
phivn = XCNEWVEC (struct phiprop_d, num_ssa_names);
|
|
|
|
if (tree_ssa_phiprop_1 (ENTRY_BLOCK_PTR, phivn, num_ssa_names))
|
|
bsi_commit_edge_inserts ();
|
|
|
|
free (phivn);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool
|
|
gate_phiprop (void)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
struct tree_opt_pass pass_phiprop = {
|
|
"phiprop", /* name */
|
|
gate_phiprop, /* gate */
|
|
tree_ssa_phiprop, /* execute */
|
|
NULL, /* sub */
|
|
NULL, /* next */
|
|
0, /* static_pass_number */
|
|
TV_TREE_FORWPROP, /* tv_id */
|
|
PROP_cfg | PROP_ssa, /* properties_required */
|
|
0, /* properties_provided */
|
|
0, /* properties_destroyed */
|
|
0, /* todo_flags_start */
|
|
TODO_dump_func
|
|
| TODO_ggc_collect
|
|
| TODO_update_ssa
|
|
| TODO_verify_ssa, /* todo_flags_finish */
|
|
0 /* letter */
|
|
};
|