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.

manual/arith.texi

@@ -1895,9 +1895,10 @@ propagated from NaN inputs to the result of a floating-point
 operation.  These functions, defined by TS 18661-1:2014 and TS
 18661-3:2015, return the payload of the NaN pointed to by @var{x}
 (returned as a positive integer, or positive zero, represented as a
-floating-point number); if @var{x} is not a NaN, they return an
+floating-point number); if @var{x} is not a NaN, they return
-unspecified value.  They raise no floating-point exceptions even for
+@minus{}1.  They raise no floating-point exceptions even for signaling
-signaling NaNs.
+NaNs.  (The return value of @minus{}1 for an argument that is not a
+NaN is specified in C2x; the value was unspecified in TS 18661.)
 @end deftypefun
 
 @deftypefun int setpayload (double *@var{x}, double @var{payload})

math/libm-test-getpayload.inc

@@ -20,17 +20,17 @@
 
 static const struct test_f_f_data getpayload_test_data[] =
   {
-    TEST_fp_f (getpayload, plus_infty, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, plus_infty, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, minus_infty, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, minus_infty, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, plus_zero, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, plus_zero, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, minus_zero, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, minus_zero, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, 1000, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, 1000, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, max_value, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, max_value, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, -max_value, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, -max_value, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, min_value, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, min_value, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, -min_value, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, -min_value, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, min_subnorm_value, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, min_subnorm_value, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
-    TEST_fp_f (getpayload, -min_subnorm_value, IGNORE, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_fp_f (getpayload, -min_subnorm_value, -1.0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
 #if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
     TEST_fp_f (getpayload, snan_value_pl ("0x0"), plus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
     TEST_fp_f (getpayload, -snan_value_pl ("0x0"), plus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),

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)

sysdeps/ieee754/dbl-64/wordsize-64/s_getpayload.c

@@ -26,6 +26,9 @@ __getpayload (const double *x)
 {
   uint64_t ix;
   EXTRACT_WORDS64 (ix, *x);
+  if ((ix & 0x7ff0000000000000ULL) != 0x7ff0000000000000ULL
+      || (ix & 0xfffffffffffffULL) == 0)
+    return -1;
   ix &= 0x7ffffffffffffULL;
   return (double) ix;
 }

sysdeps/ieee754/flt-32/s_getpayloadf.c

@@ -27,6 +27,9 @@ __getpayloadf (const float *x)
 {
   uint32_t ix;
   GET_FLOAT_WORD (ix, *x);
+  if ((ix & 0x7f800000) != 0x7f800000
+      || (ix & 0x7fffff) == 0)
+    return -1;
   ix &= 0x3fffff;
   if (FIX_INT_FP_CONVERT_ZERO && ix == 0)
     return 0.0f;

sysdeps/ieee754/ldbl-128/s_getpayloadl.c

@@ -26,6 +26,9 @@ __getpayloadl (const _Float128 *x)
 {
   uint64_t hx, lx;
   GET_LDOUBLE_WORDS64 (hx, lx, *x);
+  if ((hx & 0x7fff000000000000ULL) != 0x7fff000000000000ULL
+      || ((hx & 0xffffffffffffULL) | lx) == 0)
+    return -1;
   hx &= 0x7fffffffffffULL;
   /* Construct the representation of the return value directly, since
      128-bit integers may not be available.  */

sysdeps/ieee754/ldbl-128ibm/s_getpayloadl.c

@@ -27,6 +27,9 @@ __getpayloadl (const long double *x)
   double xhi = ldbl_high (*x);
   uint64_t ix;
   EXTRACT_WORDS64 (ix, xhi);
+  if ((ix & 0x7ff0000000000000ULL) != 0x7ff0000000000000ULL
+      || (ix & 0xfffffffffffffULL) == 0)
+    return -1;
   ix &= 0x7ffffffffffffULL;
   if (FIX_INT_FP_CONVERT_ZERO && ix == 0)
     return 0.0L;

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;