Hi!
I forgot one line, which means that if the second operand of the multiplication
isn't constant, it would be just the same as the first one.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
committed as obvious to trunk.
2021-01-18 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/98727
* tree-ssa-math-opts.c (match_arith_overflow): Fix up computation of
second .MUL_OVERFLOW operand for signed multiplication with overflow
checking if the second operand of multiplication is not constant.
* gcc.c-torture/execute/pr98727.c: New test.
--- gcc/tree-ssa-math-opts.c.jj 2021-01-12 11:04:39.000000000 +0100
+++ gcc/tree-ssa-math-opts.c 2021-01-18 13:36:38.707210300 +0100
@@ -4170,6 +4170,7 @@ match_arith_overflow (gimple_stmt_iterat
rhs2 = fold_convert (type, rhs2);
else
{
+ g = SSA_NAME_DEF_STMT (rhs2);
if (gimple_assign_cast_p (g)
&& useless_type_conversion_p (type,
TREE_TYPE (gimple_assign_rhs1 (g)))
--- gcc/testsuite/gcc.c-torture/execute/pr98727.c.jj 2021-01-18
13:47:00.227192663 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr98727.c 2021-01-18
13:46:29.511539475 +0100
@@ -0,0 +1,20 @@
+/* PR tree-optimization/98727 */
+
+__attribute__((noipa)) long int
+foo (long int x, long int y)
+{
+ long int z = (unsigned long) x * y;
+ if (x != z / y)
+ return -1;
+ return z;
+}
+
+int
+main ()
+{
+ if (foo (4, 24) != 96
+ || foo (124, 126) != 124L * 126
+ || foo (__LONG_MAX__ / 16, 17) != -1)
+ __builtin_abort ();
+ return 0;
+}
Jakub
