sync0sync.ic InnoDB now uses XCHG to implement mutex if GCC and x86

configure.in	InnoDB now uses XCHG to implement mutex if GCC and x86

BitKeeper/etc/logging_ok

 mwagner@evoq.mwagner.org
 sasha@mysql.sashanet.com
+heikki@donna.mysql.fi

innobase/configure.in

@@ -95,6 +95,11 @@ case "$target_os" in
 	 CFLAGS="$CFLAGS -DUNIV_MUST_NOT_INLINE";;
 esac
 
+case "$target" in
+       i[[4567]]86-*-*)
+	 CFLAGS="$CFLAGS -DUNIV_INTEL_X86";;
+esac
+
 AC_OUTPUT(Makefile os/Makefile ut/Makefile btr/Makefile
 		buf/Makefile com/Makefile data/Makefile
 		dict/Makefile dyn/Makefile

innobase/include/sync0sync.ic

@@ -86,6 +86,20 @@ mutex_test_and_set(
 	/* mutex_fence(); */
 
 	return(res);
+#elif defined(__GNUC__) && defined(UNIV_INTEL_X86)
+	ulint*	lw;
+	ulint	res;
+
+	lw = &(mutex->lock_word);
+
+	/* In assembly we use the so-called AT & T syntax where
+	the order of operands is inverted compared to the ordinary Intel
+	syntax. The 'l' after the mnemonics denotes a 32-bit operation. */
+
+	asm volatile("movl $1, %%eax; xchgl (%%ecx), %%eax" :
+	              "=eax" (res):
+	              "ecx" (lw));
+	return(res);
 #else
 	ibool	ret;