'inf/inf' should raise an invalid operation exception at runtime. So it
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 "inf/inf".
gcc/testsuite
* gcc.dg/pr95115.c: New test.
---
gcc/fold-const.cc | 8 ++++++++
gcc/testsuite/gcc.dg/pr95115.c | 25 +++++++++++++++++++++++++
2 files changed, 33 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr95115.c
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index fd9c6352d4f..0e99d5a2e3d 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -1283,6 +1283,14 @@ const_binop (enum tree_code code, tree arg1, tree arg2)
&& (flag_trapping_math || ! MODE_HAS_INFINITIES (mode)))
return NULL_TREE;
+ /* Don't perform "inf/inf", because it would raise an invalid
+ operation exception (IEEE 754 section 7.2 clause d). */
+ if (code == RDIV_EXPR
+ && flag_trapping_math
+ && REAL_VALUE_ISINF (d1)
+ && REAL_VALUE_ISINF (d2))
+ return NULL_TREE;
+
/* If either operand is a NaN, just return it. Otherwise, set up
for floating-point trap; we return an overflow. */
if (REAL_VALUE_ISNAN (d1))
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
