Use C2x return value from getpayload of non-NaN (bug 26073).

In TS 18661-1, getpayload had an unspecified return value for a
non-NaN argument, while C2x requires the return value -1 in that case.

This patch implements the return value of -1.  I don't think this is
worth having a new symbol version that's an alias of the old one,
although occasionally we do that in such cases where the new function
semantics are a refinement of the old ones (to avoid programs relying
on the new semantics running on older glibc versions but not behaving
as intended).

Tested for x86_64 and x86; also ran math/ tests for aarch64 and
powerpc.

1 files changed, 3 insertions, 0 deletions

diff --git a/sysdeps/ieee754/dbl-64/s_getpayload.c b/sysdeps/ieee754/dbl-64/s_getpayload.c
index 3ab89ddd66..5a055be35a 100644
--- a/sysdeps/ieee754/dbl-64/s_getpayload.c
+++ b/sysdeps/ieee754/dbl-64/s_getpayload.c
@@ -27,6 +27,9 @@ __getpayload (const double *x)
 {
   uint32_t hx, lx;
   EXTRACT_WORDS (hx, lx, *x);
+  if ((hx & 0x7ff00000) != 0x7ff00000
+      || ((hx & 0xfffff) | lx) == 0)
+    return -1;
   hx &= 0x7ffff;
   uint64_t ix = ((uint64_t) hx << 32) | lx;
   if (FIX_INT_FP_CONVERT_ZERO && ix == 0)