* lib/totalorderl.c (LDBL_SIGNBIT_WORD): Define to -1 if not defined.
(totalorderl): Avoid unused local zu by preferring ‘if’ to ‘ifdef’.
Don’t assume sizeof (unsigned long long) == 2 * sizeof (unsigned).
---
ChangeLog | 7 +++++++
lib/totalorderl.c | 38 +++++++++++++++++++++-----------------
2 files changed, 28 insertions(+), 17 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 31e02bbf4a..bf205bd23f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2023-10-05 Paul Eggert <egg...@cs.ucla.edu>
+
+ totalorderl: minor porting fixes
+ * lib/totalorderl.c (LDBL_SIGNBIT_WORD): Define to -1 if not defined.
+ (totalorderl): Avoid unused local zu by preferring ‘if’ to ‘ifdef’.
+ Don’t assume sizeof (unsigned long long) == 2 * sizeof (unsigned).
+
2023-10-04 Bruno Haible <br...@clisp.org>
totalorder* tests: Refactor.
diff --git a/lib/totalorderl.c b/lib/totalorderl.c
index cf7da088ac..cc0698febe 100644
--- a/lib/totalorderl.c
+++ b/lib/totalorderl.c
@@ -20,6 +20,10 @@
#include <math.h>
+#ifndef LDBL_SIGNBIT_WORD
+# define LDBL_SIGNBIT_WORD (-1)
+#endif
+
int
totalorderl (long double const *x, long double const *y)
{
@@ -27,7 +31,7 @@ totalorderl (long double const *x, long double const *y)
on some obsolete platforms (e.g., PA-RISC, MIPS before alignment
to IEEE 754-2008), it should be good enough nowadays. */
- /* If the sign bits of *X and *Y differ, the one with sign bit == 1
+ /* If the sign bits of *X and *Y differ, the one with non-zero sign bit
is "smaller" than the one with sign bit == 0. */
int xs = signbit (*x);
int ys = signbit (*y);
@@ -59,28 +63,28 @@ totalorderl (long double const *x, long double const *y)
return (xu.i ^ extended_sign) <= (yu.i ^ extended_sign);
}
- union { unsigned long long i[2]; long double f; } volatile xu, yu, zu;
- /* It would be tempting to initialize xu, yu, zu with {0}. But
- Solaris cc (Sun C 5.8) on x86_64 miscompiles it: It initializes
- only the lower 80 bits, not the entire 128 bits, of each of the
- three variables. */
+ union u { unsigned long long i[2]; long double f; } volatile xu, yu;
+ /* Although it is tempting to initialize with {0}, Solaris cc (Sun C 5.8)
+ on x86_64 miscompiles {0}: it initializes only the lower 80 bits,
+ not the entire 128 bits. */
xu.i[0] = 0; xu.i[1] = 0;
yu.i[0] = 0; yu.i[1] = 0;
- zu.i[0] = 0; zu.i[1] = 0;
-
xu.f = *x;
yu.f = *y;
- /* Determine in which of the two 'unsigned long long' words the sign bit
- is located. */
+ /* Set BIGENDIAN to true if and only if the most significant bits of
+ xu.f's fraction are in xu.i[0]. Use the sign bit's location to
+ infer BIGENDIAN. */
bool bigendian;
-#if defined LDBL_SIGNBIT_WORD
- /* We have already determined the sign bit location at configure time. */
- bigendian = (LDBL_SIGNBIT_WORD < 2);
-#else
- zu.f = -zu.f;
- bigendian = !!zu.i[0];
-#endif
+ if (LDBL_SIGNBIT_WORD < 0)
+ {
+ union u volatile zu;
+ zu.i[0] = 0; zu.i[1] = 0;
+ zu.f = -zu.f;
+ bigendian = !!zu.i[0];
+ }
+ else
+ bigendian = LDBL_SIGNBIT_WORD < sizeof xu.i[0] / sizeof (unsigned);
unsigned long long
xhi = xu.i[!bigendian] ^ extended_sign,
--
2.39.2
