Thanks for reporting that problem. I installed the attached patch into
Gnulib on Savannah, which I hope fixes things for you. Please give it a
try on your platform.From 55a366a06fbd98bf13adc531579e3513cee97a32 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Sun, 6 Jul 2025 12:33:06 -0700
Subject: [PATCH] float-h-tests: port to C23 PowerPC GCC
Problem reported by C. Neidhal
<https://lists.gnu.org/r/bug-gnulib/2025-07/msg00021.html>.
* modules/float-h-tests (Depends-on): Add floorl, frexpl, ldexpl.
(test_float_h_LDADD): Link the resulting libms too.
* tests/test-float-h.c: Include math.h.
(normalize_long_double): New function.
(test_long_double): Use it.
---
ChangeLog | 11 +++++++++++
modules/float-h-tests | 4 ++++
tests/test-float-h.c | 28 +++++++++++++++++++++++++++-
3 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index 286d589d23..df445d4b76 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2025-07-06 Paul Eggert <egg...@cs.ucla.edu>
+
+ float-h-tests: port to C23 PowerPC GCC
+ Problem reported by C. Neidhal
+ <https://lists.gnu.org/r/bug-gnulib/2025-07/msg00021.html>.
+ * modules/float-h-tests (Depends-on): Add floorl, frexpl, ldexpl.
+ (test_float_h_LDADD): Link the resulting libms too.
+ * tests/test-float-h.c: Include math.h.
+ (normalize_long_double): New function.
+ (test_long_double): Use it.
+
2025-07-06 Collin Funk <collin.fu...@gmail.com>
pagealign_alloc: Don't assume pointers fit in 'unsigned long'.
diff --git a/modules/float-h-tests b/modules/float-h-tests
index 6ebf0b5f31..3ac3532501 100644
--- a/modules/float-h-tests
+++ b/modules/float-h-tests
@@ -5,6 +5,9 @@ tests/macros.h
Depends-on:
fpieee
fpucw
+floorl
+frexpl
+ldexpl
isnanf-nolibm
isnand-nolibm
isnanl-nolibm
@@ -15,3 +18,4 @@ configure.ac:
Makefile.am:
TESTS += test-float-h
check_PROGRAMS += test-float-h
+test_float_h_LDADD = $(LDADD) @FLOORL_LIBM@ @FREXPL_LIBM@ @LDEXPL_LIBM@
diff --git a/tests/test-float-h.c b/tests/test-float-h.c
index b1246f6193..c0440bc3f0 100644
--- a/tests/test-float-h.c
+++ b/tests/test-float-h.c
@@ -101,6 +101,8 @@ long double ls = LDBL_SNAN; /* added in ISO C 23 */
/* ------------------------------------------------------------------------- */
+#include <math.h>
+
#include "fpucw.h"
#include "isnanf-nolibm.h"
#include "isnand-nolibm.h"
@@ -396,6 +398,30 @@ test_double (void)
/* -------------------- Check macros for 'long double' -------------------- */
+/* Return X after normalization. This makes a difference on PowerPC
+ platforms where long double uses a "double double" format that does
+ not conform to the C23 rules for floating point. On such a platform,
+ FLT_RADIX = 2, LDBL_MANT_DIG = 106, LDBL_EPSILON = 2**-105, and
+ 1 < 1 + e < 1 + LDBL_EPSILON, where e = 2**-106 and 1 + e is a
+ representable long double value that is not normalized.
+ On such a platform, normalize_long_double (1 + e) returns 1. */
+static long double
+normalize_long_double (long double volatile x)
+{
+ if (FLT_RADIX == 2)
+ {
+ int xexp;
+ long double volatile xfrac = frexpl (x, &xexp);
+ x = ldexpl (floorl (ldexpl (xfrac, LDBL_MANT_DIG - xexp)),
+ xexp - LDBL_MANT_DIG);
+ }
+ else
+ {
+ /* Hope that X is already normalized. */
+ }
+ return x;
+}
+
static void
test_long_double (void)
{
@@ -455,7 +481,7 @@ test_long_double (void)
for (n = 0; n <= 2 * LDBL_MANT_DIG; n++)
{
volatile long double half_n = pow2l (- n); /* 2^-n */
- volatile long double x = me - half_n;
+ volatile long double x = normalize_long_double (me - half_n);
if (x < me)
ASSERT (x <= 1.0L);
}
--
2.48.1
