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authoryufeng <yufeng@138bc75d-0d04-0410-961f-82ee72b054a4>2013-10-25 17:25:08 +0000
committeryufeng <yufeng@138bc75d-0d04-0410-961f-82ee72b054a4>2013-10-25 17:25:08 +0000
commite0df5be051c367d86bd11a1ca19beacb9d28983c (patch)
treeaccdc86c368a7cdb19555cc714cf66b2b7c88f27 /gcc/tree-ssa-math-opts.c
parent42681840e394597dfdd824248e4207d349b51187 (diff)
downloadgcc-e0df5be051c367d86bd11a1ca19beacb9d28983c.tar.gz
gcc/
* tree-ssa-math-opts.c (convert_plusminus_to_widen): Call has_single_use () and not do the conversion if has_single_use () returns false for the multiplication result. gcc/testsuite/ * gcc.dg/wmul-1.c: New test. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@204072 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/tree-ssa-math-opts.c')
-rw-r--r--gcc/tree-ssa-math-opts.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 1817c20772c..9a294111945 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -2432,20 +2432,25 @@ convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
It might also appear that it would be sufficient to use the existing
operands of the widening multiply, but that would limit the choice of
- multiply-and-accumulate instructions. */
+ multiply-and-accumulate instructions.
+
+ If the widened-multiplication result has more than one uses, it is
+ probably wiser not to do the conversion. */
if (code == PLUS_EXPR
&& (rhs1_code == MULT_EXPR || rhs1_code == WIDEN_MULT_EXPR))
{
- if (!is_widening_mult_p (rhs1_stmt, &type1, &mult_rhs1,
- &type2, &mult_rhs2))
+ if (!has_single_use (rhs1)
+ || !is_widening_mult_p (rhs1_stmt, &type1, &mult_rhs1,
+ &type2, &mult_rhs2))
return false;
add_rhs = rhs2;
conv_stmt = conv1_stmt;
}
else if (rhs2_code == MULT_EXPR || rhs2_code == WIDEN_MULT_EXPR)
{
- if (!is_widening_mult_p (rhs2_stmt, &type1, &mult_rhs1,
- &type2, &mult_rhs2))
+ if (!has_single_use (rhs2)
+ || !is_widening_mult_p (rhs2_stmt, &type1, &mult_rhs1,
+ &type2, &mult_rhs2))
return false;
add_rhs = rhs1;
conv_stmt = conv2_stmt;