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author | yufeng <yufeng@138bc75d-0d04-0410-961f-82ee72b054a4> | 2013-10-25 17:25:08 +0000 |
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committer | yufeng <yufeng@138bc75d-0d04-0410-961f-82ee72b054a4> | 2013-10-25 17:25:08 +0000 |
commit | e0df5be051c367d86bd11a1ca19beacb9d28983c (patch) | |
tree | accdc86c368a7cdb19555cc714cf66b2b7c88f27 /gcc/tree-ssa-math-opts.c | |
parent | 42681840e394597dfdd824248e4207d349b51187 (diff) | |
download | gcc-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.c | 15 |
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; |