Bootstrapped and tested on x86_64-linux-gnu. Ok for trunk, gcc-11, and
gcc-10? (I'd consider PR 95115 a 10/11/12 regression because GCC
10/11/12 miscompiles glibc acos/asin function, but not GCC 9.)
These operations should raise an invalid operation exception at runtime.
So they should not be folded during compilation unless -fno-trapping-math
is used.
gcc/
PR middle-end/95115
* fold-const.cc (const_binop): Do not fold NaN result from
non-NaN operands.
gcc/testsuite
* gcc.dg/pr95115.c: New test.
---
gcc/fold-const.cc | 11 +++++++++++
gcc/testsuite/gcc.dg/pr95115.c | 25 +++++++++++++++++++++++++
2 files changed, 36 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr95115.c
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index b155611578d..8fc01cdfb77 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -1305,6 +1305,17 @@ const_binop (enum tree_code code, tree arg1, tree arg2)
inexact = real_arithmetic (&value, code, &d1, &d2);
real_convert (&result, mode, &value);
+ /* Don't constant fold this floating point operation if
+ both operands are not NaN but the result is NaN, and
+ flag_trapping_math. Such operations should raise an
+ invalid operation exception. */
+ if (flag_trapping_math
+ && MODE_HAS_NANS (mode)
+ && REAL_VALUE_ISNAN (result)
+ && !REAL_VALUE_ISNAN (d1)
+ && !REAL_VALUE_ISNAN (d2))
+ return NULL_TREE;
+
/* Don't constant fold this floating point operation if
the result has overflowed and flag_trapping_math. */
if (flag_trapping_math
diff --git a/gcc/testsuite/gcc.dg/pr95115.c b/gcc/testsuite/gcc.dg/pr95115.c
new file mode 100644
index 00000000000..46a95dfb698
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr95115.c
@@ -0,0 +1,25 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -ftrapping-math" } */
+/* { dg-add-options ieee } */
+/* { dg-require-effective-target fenv_exceptions } */
+
+#include <fenv.h>
+#include <stdlib.h>
+
+double
+x (void)
+{
+ double d = __builtin_inf ();
+ return d / d;
+}
+
+int
+main (void)
+{
+ double r = x ();
+ if (!__builtin_isnan (r))
+ abort ();
+ if (!fetestexcept (FE_INVALID))
+ abort ();
+ exit (0);
+}
--
2.35.1
