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re PR tree-optimization/31146 (forwprop does not look through casts)

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2007-05-02  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/31146
	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): New
	argument, single_use_p.  If we have a single use that is
	a conversion to the definition rhs type, propagate that rhs.
	(forward_propagate_addr_expr): Pass single_use_p argument
	to forward_propagate_addr_expr_1.

	* g++.dg/tree-ssa/pr31146-2.C: New testcase.

From-SVN: r124349
This commit is contained in:
Richard Guenther 2007-05-02 09:12:49 +00:00 committed by Richard Biener
parent d7598e110d
commit f6c5fefc1d
4 changed files with 55 additions and 4 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2007-05-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/31146
* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): New
argument, single_use_p. If we have a single use that is
a conversion to the definition rhs type, propagate that rhs.
(forward_propagate_addr_expr): Pass single_use_p argument
to forward_propagate_addr_expr_1.
2007-05-01 H.J. Lu <hongjiu.lu@intel.com>
* config/i386/i386.c (ix86_expand_sse_comi): Remove unused

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2007-05-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/31146
* g++.dg/tree-ssa/pr31146-2.C: New testcase.
2007-05-01 Geoffrey Keating <geoffk@apple.com>
* gcc.c-torture/compile/limits-blockid.c: New.

24
gcc/testsuite/g++.dg/tree-ssa/pr31146-2.C Normal file
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@ -0,0 +1,24 @@
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-forwprop1" } */
#include <new>
template <class T>
struct Vec
{
Vec()
{
for (int i=0; i<3; ++i)
new (&a[i]) T(0);
}
T a[3];
};
double foo (void)
{
Vec<double> v;
return v.a[2];
}
/* { dg-final { scan-tree-dump "Replaced .*iftmp.* != 0B. with .1" "forwprop1" } } */
/* { dg-final { cleanup-tree-dump "forwprop1" } } */

21
gcc/tree-ssa-forwprop.c
View File

@ -559,7 +559,8 @@ forward_propagate_addr_into_variable_array_index (tree offset, tree lhs,
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)
forward_propagate_addr_expr_1 (tree name, tree def_rhs, tree use_stmt,
bool single_use_p)
{
tree lhs, rhs, array_ref;
@ -584,10 +585,20 @@ forward_propagate_addr_expr_1 (tree name, tree def_rhs, tree use_stmt)
/* Continue propagating into the RHS. */
}
/* Trivial case. The use statement could be a trivial copy or a
/* 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. */
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
@ -702,6 +713,7 @@ forward_propagate_addr_expr (tree name, tree rhs)
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)
{
@ -726,7 +738,8 @@ forward_propagate_addr_expr (tree name, tree rhs)
push_stmt_changes (&use_stmt);
result = forward_propagate_addr_expr_1 (name, rhs, use_stmt);
result = forward_propagate_addr_expr_1 (name, rhs, use_stmt,
single_use_p);
all &= result;
pop_stmt_changes (&use_stmt);