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/ldbl-96/s_getpayloadl.c b/sysdeps/ieee754/ldbl-96/s_getpayloadl.c
index 8f09cb74c8..761bd69b58 100644
--- a/sysdeps/ieee754/ldbl-96/s_getpayloadl.c
+++ b/sysdeps/ieee754/ldbl-96/s_getpayloadl.c
@@ -27,6 +27,9 @@ __getpayloadl (const long double *x)
   uint16_t se __attribute__ ((unused));
   uint32_t hx, lx;
   GET_LDOUBLE_WORDS (se, hx, lx, *x);
+  if ((se & 0x7fff) != 0x7fff
+      || ((hx & 0x7fffffff) | lx) == 0)
+    return -1;
   hx &= 0x3fffffff;
   uint64_t ix = ((uint64_t) hx << 32) | lx;
   return (long double) ix;