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Hi!
On IA-64 and S390, if __bswap_{16,32,64}(*x++) and similar constructs are
used (heavily e.g. in sunrpc on IA-64), gcc emits tons of
operation on `something' may be undefined warnings.
It is because __bswap_constant_* macros are used on the original x,
so gcc sees if (__builtin_constant_p (*x++)) __v = ((*x++) >> 8) | ((*x++) << 8);
else something and warns before optimizing the __builtin_constant_p
and the false branch away.
Following patch shuts it up, plus wraps for non-GCC the macros in static
__inline functions like sysdeps/generic/bits/byteswap.h does, so that
it doesn't evaluate arguments multiple times.
2003-01-07 Jakub Jelinek <jakub@redhat.com>
* sysdeps/ia64/bits/byteswap.h [__GNUC__ >= 2] (__bswap_16,
__bswap_32, __bswap_64): Put x into temporary variable
to avoid warnings.
[!__GNUC__] (__bswap_16, __bswap_32, __bswap_64): Change into static
(inline) functions.
* sysdeps/s390/bits/byteswap.h [__GNUC__ >= 2] (__bswap_16,
__bswap_32, __bswap_64): Put x into temporary variable
to avoid warnings.
[!__GNUC__] (__bswap_16, __bswap_32, __bswap_64): Change into static
(inline) functions.
* sysdeps/i386/bits/byteswap.h [!__GNUC__] (__bswap_16, __bswap_32):
Likewise.
--- libc/sysdeps/ia64/bits/byteswap.h 31 Jan 2002 21:33:01 -0000 1.1.1.4
+++ libc/sysdeps/ia64/bits/byteswap.h 7 Jan 2003 10:11:25 -0000 1.3
@@ -1,5 +1,5 @@
/* Macros to swap the order of bytes in integer values.
- Copyright (C) 1997, 1998, 2000, 2002 Free Software Foundation, Inc.
+ Copyright (C) 1997, 1998, 2000, 2002, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -31,18 +31,22 @@
#if defined __GNUC__ && __GNUC__ >= 2
# define __bswap_16(x) \
(__extension__ \
- ({ register unsigned short int __v; \
+ ({ register unsigned short int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_16 (x); \
+ __v = __bswap_constant_16 (__x); \
else \
__asm__ __volatile__ ("shl %0 = %1, 48 ;;" \
"mux1 %0 = %0, @rev ;;" \
: "=r" (__v) \
- : "r" ((unsigned short int) (x))); \
+ : "r" ((unsigned short int) (__x))); \
__v; }))
#else
/* This is better than nothing. */
-# define __bswap_16(x) __bswap_constant_16 (x)
+static __inline unsigned short int
+__bswap_16 (unsigned short int __bsx)
+{
+ return __bswap_constant_16 (__bsx);
+}
#endif
@@ -54,17 +58,21 @@
#if defined __GNUC__ && __GNUC__ >= 2
# define __bswap_32(x) \
(__extension__ \
- ({ register unsigned int __v; \
+ ({ register unsigned int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_32 (x); \
+ __v = __bswap_constant_32 (__x); \
else \
__asm__ __volatile__ ("shl %0 = %1, 32 ;;" \
"mux1 %0 = %0, @rev ;;" \
: "=r" (__v) \
- : "r" ((unsigned int) (x))); \
+ : "r" ((unsigned int) (__x))); \
__v; }))
#else
-# define __bswap_32(x) __bswap_constant_32 (x)
+static __inline unsigned int
+__bswap_32 (unsigned int __bsx)
+{
+ return __bswap_constant_32 (__bsx);
+}
#endif
@@ -82,17 +90,21 @@
#if defined __GNUC__ && __GNUC__ >= 2
# define __bswap_64(x) \
(__extension__ \
- ({ register unsigned long int __v; \
+ ({ register unsigned long int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_64 (x); \
+ __v = __bswap_constant_64 (__x); \
else \
__asm__ __volatile__ ("mux1 %0 = %1, @rev ;;" \
: "=r" (__v) \
- : "r" ((unsigned long int) (x))); \
+ : "r" ((unsigned long int) (__x))); \
__v; }))
#else
-# define __bswap_64(x) __bswap_constant_64 (x)
+static __inline unsigned long int
+__bswap_64 (unsigned long int __bsx)
+{
+ return __bswap_constant_64 (__bsx);
+}
#endif
#endif /* _BITS_BYTESWAP_H */
--- libc/sysdeps/s390/bits/byteswap.h 24 Jul 2002 15:29:44 -0000 1.1.1.2
+++ libc/sysdeps/s390/bits/byteswap.h 7 Jan 2003 22:12:51 -0000 1.6
@@ -1,5 +1,5 @@
/* Macros to swap the order of bytes in integer values. s390 version.
- Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
This file is part of the GNU C Library.
@@ -35,11 +35,11 @@
# if __WORDSIZE == 64
# define __bswap_16(x) \
(__extension__ \
- ({ unsigned short int __v; \
+ ({ unsigned short int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_16 (x); \
+ __v = __bswap_constant_16 (__x); \
else { \
- unsigned short int __tmp = (unsigned short int) (x); \
+ unsigned short int __tmp = (unsigned short int) (__x); \
__asm__ __volatile__ ( \
"lrvh %0,%1" \
: "=&d" (__v) : "m" (__tmp) ); \
@@ -48,11 +48,11 @@
# else
# define __bswap_16(x) \
(__extension__ \
- ({ unsigned short int __v; \
+ ({ unsigned short int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_16 (x); \
+ __v = __bswap_constant_16 (__x); \
else { \
- unsigned short int __tmp = (unsigned short int) (x); \
+ unsigned short int __tmp = (unsigned short int) (__x); \
__asm__ __volatile__ ( \
"sr %0,%0\n" \
"la 1,%1\n" \
@@ -64,7 +64,11 @@
# endif
#else
/* This is better than nothing. */
-#define __bswap_16(x) __bswap_constant_16 (x)
+static __inline unsigned short int
+__bswap_16 (unsigned short int __bsx)
+{
+ return __bswap_constant_16 (__bsx);
+}
#endif
/* Swap bytes in 32 bit value. */
@@ -76,11 +80,11 @@
# if __WORDSIZE == 64
# define __bswap_32(x) \
(__extension__ \
- ({ unsigned int __v; \
+ ({ unsigned int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_32 (x); \
+ __v = __bswap_constant_32 (__x); \
else { \
- unsigned int __tmp = (unsigned int) (x); \
+ unsigned int __tmp = (unsigned int) (__x); \
__asm__ __volatile__ ( \
"lrv %0,%1" \
: "=&d" (__v) : "m" (__tmp)); \
@@ -89,11 +93,11 @@
# else
# define __bswap_32(x) \
(__extension__ \
- ({ unsigned int __v; \
+ ({ unsigned int __v, __x = (x); \
if (__builtin_constant_p (x)) \
- __v = __bswap_constant_32 (x); \
+ __v = __bswap_constant_32 (__x); \
else { \
- unsigned int __tmp = (unsigned int) (x); \
+ unsigned int __tmp = (unsigned int) (__x); \
__asm__ __volatile__ ( \
"la 1,%1\n" \
"icm %0,8,3(1)\n" \
@@ -105,7 +109,11 @@
__v; }))
# endif
#else
-# define __bswap_32(x) __bswap_constant_32 (x)
+static __inline unsigned int
+__bswap_32 (unsigned int __bsx)
+{
+ return __bswap_constant_32 (__bsx);
+}
#endif
/* Swap bytes in 64 bit value. */
@@ -119,11 +127,11 @@
# if __WORDSIZE == 64
# define __bswap_64(x) \
(__extension__ \
- ({ unsigned long __w; \
+ ({ unsigned long __w, __x = (x); \
if (__builtin_constant_p (x)) \
- __w = __bswap_constant_64 (x); \
+ __w = __bswap_constant_64 (__x); \
else { \
- unsigned long __tmp = (unsigned long) (x); \
+ unsigned long __tmp = (unsigned long) (__x); \
__asm__ __volatile__ ( \
"lrvg %0,%1" \
: "=&d" (__w) : "m" (__tmp)); \
@@ -140,7 +148,11 @@
__r.__ll; })
# endif
#else
-# define __bswap_64(x) __bswap_constant_64 (x)
+static __inline unsigned long long int
+__bswap_64 (unsigned long long int __bsx)
+{
+ return __bswap_constant_64 (__bsx);
+}
#endif
#endif /* _BITS_BYTESWAP_H */
--- libc/sysdeps/i386/bits/byteswap.h 12 Dec 2002 15:26:20 -0000 1.1.1.7
+++ libc/sysdeps/i386/bits/byteswap.h 12 Dec 2002 16:34:13 -0000 1.3
@@ -28,8 +28,9 @@
#define __bswap_constant_16(x) \
((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
-#if defined __GNUC__ && __GNUC__ >= 2
-# define __bswap_16(x) \
+#ifdef __GNUC__
+# if __GNUC__ >= 2
+# define __bswap_16(x) \
(__extension__ \
({ register unsigned short int __v, __x = (x); \
if (__builtin_constant_p (__x)) \
@@ -40,24 +41,31 @@
: "0" (__x) \
: "cc"); \
__v; }))
-#else
+# else
/* This is better than nothing. */
-# define __bswap_16(x) \
+# define __bswap_16(x) \
(__extension__ \
({ register unsigned short int __x = (x); __bswap_constant_16 (__x); }))
+# endif
+#else
+static __inline unsigned short int
+__bswap_16 (unsigned short int __bsx)
+{
+ return __bswap_constant_16 (__bsx);
+}
#endif
-
/* Swap bytes in 32 bit value. */
#define __bswap_constant_32(x) \
((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
(((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
-#if defined __GNUC__ && __GNUC__ >= 2
+#ifdef __GNUC__
+# if __GNUC__ >= 2
/* To swap the bytes in a word the i486 processors and up provide the
`bswap' opcode. On i386 we have to use three instructions. */
-# if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__
-# define __bswap_32(x) \
+# if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__
+# define __bswap_32(x) \
(__extension__ \
({ register unsigned int __v, __x = (x); \
if (__builtin_constant_p (__x)) \
@@ -70,8 +78,8 @@
: "0" (__x) \
: "cc"); \
__v; }))
-# else
-# define __bswap_32(x) \
+# else
+# define __bswap_32(x) \
(__extension__ \
({ register unsigned int __v, __x = (x); \
if (__builtin_constant_p (__x)) \
@@ -79,11 +87,18 @@
else \
__asm__ ("bswap %0" : "=r" (__v) : "0" (__x)); \
__v; }))
-# endif
-#else
-# define __bswap_32(x) \
+# endif
+# else
+# define __bswap_32(x) \
(__extension__ \
({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
+# endif
+#else
+static __inline unsigned int
+__bswap_32 (unsigned int __bsx)
+{
+ return __bswap_constant_32 (__bsx);
+}
#endif
Jakub
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