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PATCH: Use __builtin_bswap32/64 for GCC >= 4.2


Hi,

sysdeps/x86_64/bits/byteswap.h has

#if defined __GNUC__ && __GNUC__ >= 2
..
#else
# define __bswap_32(x) \
     (__extension__
\
      ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
#endif

It doesn't work for compilers without GCC __extension__
support.

This patch uses __builtin_bswap32/64 for GCC >= 4.2.
I used inline function instead of __extension__ to avoid
the __builtin_bswap32/64 return type issue:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37743

Tested on Linux/ia32 and Linux/x86-64.  OK to install?

Thanks.

H.J.
--
2012-04-05  H.J. Lu  <hongjiu.lu@intel.com>

	* sysdeps/i386/bits/byteswap.h: (__bswap_32): Use
	__builtin_bswap32 for GCC >= 4.2.
	(__bswap_64): Use __builtin_bswap64 for GCC >= 4.2.
	* sysdeps/x86_64/bits/byteswap.h: Likewise.

diff --git a/sysdeps/i386/bits/byteswap.h b/sysdeps/i386/bits/byteswap.h
index fb0a827..751e10d 100644
--- a/sysdeps/i386/bits/byteswap.h
+++ b/sysdeps/i386/bits/byteswap.h
@@ -60,52 +60,18 @@ __bswap_16 (unsigned short int __bsx)
      ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		      \
       (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
 
-#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__ \
-      && !defined __pentium4__ && !defined __k8__ && !defined __athlon__ \
-      && !defined __k6__ && !defined __nocona__ && !defined __core2__ \
-      && !defined __geode__ && !defined __amdfam10__
-#   define __bswap_32(x)						      \
-     (__extension__							      \
-      ({ register unsigned int __v, __x = (x);				      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else								      \
-	   __asm__ ("rorw $8, %w0;"					      \
-		    "rorl $16, %0;"					      \
-		    "rorw $8, %w0"					      \
-		    : "=r" (__v)					      \
-		    : "0" (__x)						      \
-		    : "cc");						      \
-	 __v; }))
-#  else
-#   define __bswap_32(x) \
-     (__extension__							      \
-      ({ register unsigned int __v, __x = (x);				      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else								      \
-	   __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));		      \
-	 __v; }))
-#  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)
 {
+#if defined __GNUC__ && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2))
+  return __builtin_bswap32 (__bsx);
+#else
   return __bswap_constant_32 (__bsx);
-}
 #endif
+}
 
 
-#if defined __GNUC__ && __GNUC__ >= 2
+#if defined __GNUC__ && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2))
 /* Swap bytes in 64 bit value.  */
 # define __bswap_constant_64(x) \
      (__extension__ ((((x) & 0xff00000000000000ull) >> 56)		      \
@@ -117,19 +83,11 @@ __bswap_32 (unsigned int __bsx)
 		     | (((x) & 0x000000000000ff00ull) << 40)		      \
 		     | (((x) & 0x00000000000000ffull) << 56)))
 
-# define __bswap_64(x) \
-     (__extension__							      \
-      ({ union { __extension__ unsigned long long int __ll;		      \
-		 unsigned long int __l[2]; } __w, __r;			      \
-	 if (__builtin_constant_p (x))					      \
-	   __r.__ll = __bswap_constant_64 (x);				      \
-	 else								      \
-	   {								      \
-	     __w.__ll = (x);						      \
-	     __r.__l[0] = __bswap_32 (__w.__l[1]);			      \
-	     __r.__l[1] = __bswap_32 (__w.__l[0]);			      \
-	   }								      \
-	 __r.__ll; }))
+static __inline unsigned long long int
+__bswap_64 (unsigned long long int __bsx)
+{
+  return __builtin_bswap64 (__bsx);
+}
 #elif __GLIBC_HAVE_LONG_LONG
 # define __bswap_constant_64(x) \
      ((((x) & 0xff00000000000000ull) >> 56)				      \
diff --git a/sysdeps/x86_64/bits/byteswap.h b/sysdeps/x86_64/bits/byteswap.h
index 472281f..38c42c8 100644
--- a/sysdeps/x86_64/bits/byteswap.h
+++ b/sysdeps/x86_64/bits/byteswap.h
@@ -23,8 +23,6 @@
 #ifndef _BITS_BYTESWAP_H
 #define _BITS_BYTESWAP_H 1
 
-#include <bits/wordsize.h>
-
 /* Swap bytes in 16 bit value.  */
 #define __bswap_constant_16(x) \
      ((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
@@ -55,46 +53,18 @@
      ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		      \
       (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
 
-#if defined __GNUC__ && __GNUC__ >= 2
-# if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__	      \
-			  || defined __pentiumpro__ || defined __pentium4__   \
-			  || defined __k8__ || defined __athlon__	      \
-			  || defined __k6__ || defined __nocona__	      \
-			  || defined __core2__ || defined __geode__	      \
-			  || defined __amdfam10__)
-/* To swap the bytes in a word the i486 processors and up provide the
-   `bswap' opcode.  On i386 we have to use three instructions.  */
-#  define __bswap_32(x) \
-     (__extension__							      \
-      ({ register unsigned int __v, __x = (x);				      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else								      \
-	   __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));		      \
-	 __v; }))
-# else
-#  define __bswap_32(x)							      \
-     (__extension__							      \
-      ({ register unsigned int __v, __x = (x);				      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else								      \
-	   __asm__ ("rorw $8, %w0;"					      \
-		    "rorl $16, %0;"					      \
-		    "rorw $8, %w0"					      \
-		    : "=r" (__v)					      \
-		    : "0" (__x)						      \
-		    : "cc");						      \
-	 __v; }))
-# endif
+static __inline unsigned int
+__bswap_32 (unsigned int __bsx)
+{
+#if defined __GNUC__ && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2))
+  return __builtin_bswap32 (__bsx);
 #else
-# define __bswap_32(x) \
-     (__extension__							      \
-      ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
+  return __bswap_constant_32 (__bsx);
 #endif
+}
 
 
-#if defined __GNUC__ && __GNUC__ >= 2
+#if defined __GNUC__ && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2))
 /* Swap bytes in 64 bit value.  */
 # define __bswap_constant_64(x) \
      (__extension__ ((((x) & 0xff00000000000000ull) >> 56)		      \
@@ -106,30 +76,11 @@
 		     | (((x) & 0x000000000000ff00ull) << 40)		      \
 		     | (((x) & 0x00000000000000ffull) << 56)))
 
-# if __WORDSIZE == 64
-#  define __bswap_64(x) \
-     (__extension__							      \
-      ({ register unsigned long __v, __x = (x);				      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_64 (__x);				      \
-	 else								      \
-	   __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x));		      \
-	 __v; }))
-# else
-#  define __bswap_64(x) \
-     (__extension__                                                           \
-      ({ union { __extension__ unsigned long long int __ll;                   \
-		 unsigned int __l[2]; } __w, __r;                             \
-	 if (__builtin_constant_p (x))                                        \
-	   __r.__ll = __bswap_constant_64 (x);                                \
-	 else                                                                 \
-	   {                                                                  \
-	     __w.__ll = (x);                                                  \
-	     __r.__l[0] = __bswap_32 (__w.__l[1]);                            \
-	     __r.__l[1] = __bswap_32 (__w.__l[0]);                            \
-	   }                                                                  \
-	 __r.__ll; }))
-# endif
+static __inline unsigned long long int
+__bswap_64 (unsigned long long int __bsx)
+{
+  return __builtin_bswap64 (__bsx);
+}
 #elif __GLIBC_HAVE_LONG_LONG
 # define __bswap_constant_64(x) \
      ((((x) & 0xff00000000000000ull) >> 56)				      \


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