[ARM] Fix PR target/59833

For Aurelien Jarno <aurelien@aurel32.net>

On ARM soft-float, the float to double conversion doesn't convert a sNaN
to qNaN as the IEEE Std 754 standard mandates:

"Under default exception handling, any operation signaling an invalid
operation exception and for which a floating-point result is to be
delivered shall deliver a quiet NaN."

Given the soft float ARM code ignores exceptions and always provides a
result, a float to double conversion of a signaling NaN should return a
quiet NaN. Fix this in extendsfdf2.

gcc/ChangeLog:

	PR target/59833
	* config/arm/ieee754-df.S (extendsfdf2): Convert sNaN to qNaN.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr59833.c: New testcase.

From-SVN: r238584

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/pr59833.c b/gcc/testsuite/gcc.dg/pr59833.c
new file mode 100644
index 0000000..e0e4ed5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr59833.c
@@ -0,0 +1,18 @@
+/* { dg-do run { target { *-*-linux* *-*-gnu* } } } */
+/* { dg-options "-O0 -lm" } */
+/* { dg-require-effective-target issignaling } */
+
+#define _GNU_SOURCE
+#include <math.h>
+
+int main (void)
+{
+  float sNaN = __builtin_nansf ("");
+  double x = (double) sNaN;
+  if (issignaling(x))
+  {
+    __builtin_abort();
+  }
+
+  return 0;
+}