In <https://lists.gnu.org/archive/html/bug-gnulib/2023-10/msg00060.html>
I noted that with CC="gcc -mfpmath=387" on x86_64, similar signalling
NaN problems occur as on i386. Although probably few people use this
command-line option (since it slows down the code by mixing access to
the two floating-point units), it can be worked around:
2023-10-14 Bruno Haible <br...@clisp.org>
snan: Avoid test failures with CC="gcc -mfpmath=387".
* tests/test-snan-1.c (main): Treat x86_64 CPU with
__FLT_EVAL_METHOD__ == 2 like i386 CPU. Update comments.
* tests/test-snan-2.c (main): Likewise.
diff --git a/tests/test-snan-1.c b/tests/test-snan-1.c
index fc8fc99e31..911d20bd70 100644
--- a/tests/test-snan-1.c
+++ b/tests/test-snan-1.c
@@ -61,15 +61,13 @@ main ()
long double volatile nanl = SNaNl ();
/* Check that the values are really signalling. */
- /* These tests do not work on 32-bit x86 processors, although the
- "Intel 64 and IA-32 Architectures Software Developer's Manual" and
- "IA-32 Intel Architecture Software Developer's Manual", each in
- sections
- 4.8.3.4 NaNs
- 4.8.3.5 Operating on SNaNs and QNaNs
- 4.8.3.6 Using SNaNs and QNaNs in Applications
- claim that it should work. */
- #if !(defined __i386 || defined _M_IX86)
+ /* These tests do not work on 32-bit x86 processors, as well as
+ on x86_64 processors with CC="gcc -mfpmath=387", because loading SNaNf()
+ or SNaNd() into a 387 FPU register already converted it to a quiet NaN.
+ See <https://lists.gnu.org/archive/html/bug-gnulib/2023-10/msg00060.html>
+ for details. */
+ #if !((defined __i386 || defined _M_IX86) \
+ || ((defined __x86_64__ || defined _M_X64) && __FLT_EVAL_METHOD__ ==
2))
/* This test does not work on AIX 7.1 with the xlc compiler, even with
the compiler options -qfloat=fenv -qfloat=nans -qfloat=spnans. */
#if !(defined _AIX && defined __xlC__)
diff --git a/tests/test-snan-2.c b/tests/test-snan-2.c
index 42927d6077..4ddd3ac9b1 100644
--- a/tests/test-snan-2.c
+++ b/tests/test-snan-2.c
@@ -65,15 +65,13 @@ main (int argc, char *argv[])
switch (argv[1][0])
{
case 'f':
- /* This test does not work on 32-bit x86 processors, although the
- "Intel 64 and IA-32 Architectures Software Developer's Manual" and
- "IA-32 Intel Architecture Software Developer's Manual", each in
- sections
- 4.8.3.4 NaNs
- 4.8.3.5 Operating on SNaNs and QNaNs
- 4.8.3.6 Using SNaNs and QNaNs in Applications
- claim that it should work. */
- #if !(defined __i386 || defined _M_IX86)
+ /* This test does not work on 32-bit x86 processors, as well as
+ on x86_64 processors with CC="gcc -mfpmath=387", because loading
+ SNaNf() into a 387 FPU register already converted it to a quiet NaN.
+ See
<https://lists.gnu.org/archive/html/bug-gnulib/2023-10/msg00060.html>
+ for details. */
+ #if !((defined __i386 || defined _M_IX86) \
+ || ((defined __x86_64__ || defined _M_X64) &&
__FLT_EVAL_METHOD__ == 2))
/* This test does not work on AIX 7.1 with the xlc compiler, even with
the compiler options -qfloat=fenv -qfloat=nans -qfloat=spnans. */
#if !(defined _AIX && defined __xlC__)
@@ -89,15 +87,13 @@ main (int argc, char *argv[])
break;
case 'd':
- /* This test does not work on 32-bit x86 processors, although the
- "Intel 64 and IA-32 Architectures Software Developer's Manual" and
- "IA-32 Intel Architecture Software Developer's Manual", each in
- sections
- 4.8.3.4 NaNs
- 4.8.3.5 Operating on SNaNs and QNaNs
- 4.8.3.6 Using SNaNs and QNaNs in Applications
- claim that it should work. */
- #if !(defined __i386 || defined _M_IX86)
+ /* This test does not work on 32-bit x86 processors, as well as
+ on x86_64 processors with CC="gcc -mfpmath=387", because loading
+ SNaNd() into a 387 FPU register already converted it to a quiet NaN.
+ See
<https://lists.gnu.org/archive/html/bug-gnulib/2023-10/msg00060.html>
+ for details. */
+ #if !((defined __i386 || defined _M_IX86) \
+ || ((defined __x86_64__ || defined _M_X64) &&
__FLT_EVAL_METHOD__ == 2))
resultd = nand + 42.0;
#else
fputs ("Skipping test: known failure on this platform\n", stderr);
@@ -125,7 +121,9 @@ main (int argc, char *argv[])
|| ((defined __FreeBSD__ || defined __NetBSD__ || defined
__OpenBSD__) && (defined __aarch64__ || defined __sparc__))) \
&& !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE) \
|| (defined __CYGWIN__ && defined __i386) \
- || ((defined __i386 || defined _M_IX86) &&
HAVE_SAME_LONG_DOUBLE_AS_DOUBLE))
+ || (((defined __i386 || defined _M_IX86) \
+ || ((defined __x86_64__ || defined _M_X64) &&
__FLT_EVAL_METHOD__ == 2)) \
+ && HAVE_SAME_LONG_DOUBLE_AS_DOUBLE))
resultl = nanl + 42.0L;
#else
fputs ("Skipping test: known failure on this platform\n", stderr);
