OpenE2K
/
gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

match.pd: Fix x * 0.0 -> 0.0 folding [PR104389] 

The recent PR95115 change to punt in const_binop on folding operation
with non-NaN operands into NaN if flag_trapping_math broke the following
testcase, because the x * 0.0 simplification punts just if
x maybe a NaN (because NaN * 0.0 is NaN not 0.0) or if one of the operands
could be negative zero.  But Inf * 0.0 or -Inf * 0.0 is also NaN, not
0.0, so when NaNs are honored we need to punt for possible infinities too.

2022-02-05  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/104389
	* match.pd (x * 0 -> 0): Punt if x maybe infinite and NaNs are
	honored.

	* gcc.dg/pr104389.c: New test.
This commit is contained in:
Jakub Jelinek 2022-02-05 10:52:19 +01:00
parent affdeda16e
commit b3763384a1
2 changed files with 29 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
gcc/match.pd
View File

@ -256,10 +256,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Maybe fold x * 0 to 0. The expressions aren't the same
when x is NaN, since x * 0 is also NaN. Nor are they the
same in modes with signed zeros, since multiplying a
negative value by 0 gives -0, not +0. */
negative value by 0 gives -0, not +0. Nor when x is +-Inf,
since x * 0 is NaN. */
(simplify
(mult @0 real_zerop@1)
(if (!tree_expr_maybe_nan_p (@0)
&& (!HONOR_NANS (type) || !tree_expr_maybe_infinite_p (@0))
&& !tree_expr_maybe_real_minus_zero_p (@0)
&& !tree_expr_maybe_real_minus_zero_p (@1))
@1))

26
gcc/testsuite/gcc.dg/pr104389.c Normal file
View File

@ -0,0 +1,26 @@
/* PR tree-optimization/104389 */
/* { dg-do run } */
/* { dg-options "-O2" } */
/* { dg-add-options ieee } */
/* { dg-require-effective-target inf } */
__attribute__((noipa)) double
foo (void)
{
double a = __builtin_huge_val ();
return a * 0.0;
}
__attribute__((noipa)) long double
bar (void)
{
return __builtin_huge_vall () * 0.0L;
}
int
main ()
{
if (!__builtin_isnan (foo ()) || !__builtin_isnanl (bar ()))
__builtin_abort ();
return 0;
}