Bug 452912 - Optimize Windows x64 build for javascript engine. r=dvander

js/src/jsbit.h

@@ -78,7 +78,7 @@ extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i);
  *
  * SWS: Added MSVC intrinsic bitscan support.  See bugs 349364 and 356856.
  */
-#if defined(_WIN32) && (_MSC_VER >= 1300) && defined(_M_IX86)
+#if defined(_WIN32) && (_MSC_VER >= 1300) && (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64))
 
 unsigned char _BitScanForward(unsigned long * Index, unsigned long Mask);
 unsigned char _BitScanReverse(unsigned long * Index, unsigned long Mask);
@@ -104,6 +104,31 @@ __BitScanReverse32(unsigned int val)
 # define js_bitscan_clz32(val)  __BitScanReverse32(val)
 # define JS_HAS_BUILTIN_BITSCAN32
 
+#if defined(_M_AMD64) || defined(_M_X64)
+unsigned char _BitScanForward64(unsigned long * Index, unsigned __int64 Mask);
+unsigned char _BitScanReverse64(unsigned long * Index, unsigned __int64 Mask);
+# pragma intrinsic(_BitScanForward64,_BitScanReverse64)
+
+__forceinline static int
+__BitScanForward64(unsigned __int64 val)
+{
+    unsigned long idx;
+
+    _BitScanForward64(&idx, val);
+    return (int)idx;
+}
+__forceinline static int
+__BitScanReverse64(unsigned __int64 val)
+{
+    unsigned long idx;
+
+    _BitScanReverse64(&idx, val);
+    return (int)(63-idx);
+}
+# define js_bitscan_ctz64(val)  __BitScanForward64(val)
+# define js_bitscan_clz64(val)  __BitScanReverse64(val)
+# define JS_HAS_BUILTIN_BITSCAN64
+#endif
 #elif (__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 
 # define js_bitscan_ctz32(val)  __builtin_ctz(val)

js/src/jslock.cpp

@@ -91,6 +91,19 @@ NativeCompareAndSwap(jsword *w, jsword ov, jsword nv)
     return (NativeCompareAndSwapHelper(w, ov, nv) & 1);
 }
 
+#elif defined(_MSC_VER) && (defined(_M_AMD64) || defined(_M_X64))
+JS_BEGIN_EXTERN_C
+extern long long __cdecl
+_InterlockedCompareExchange64(long long *volatile dest, long long exchange, long long comp);
+JS_END_EXTERN_C
+#pragma intrinsic(_InterlockedCompareExchange64)
+
+static JS_ALWAYS_INLINE int
+NativeCompareAndSwap(jsword *w, jsword ov, jsword nv)
+{
+    return _InterlockedCompareExchange64(w, nv, ov) == ov;
+}
+
 #elif defined(XP_MACOSX) || defined(DARWIN)
 
 #include <libkern/OSAtomic.h>

js/src/jslock.h

@@ -55,6 +55,7 @@ JS_BEGIN_EXTERN_C
 #ifdef JS_THREADSAFE
 
 #if (defined(_WIN32) && defined(_M_IX86)) ||                                  \
+    (defined(_WIN64) && (defined(_M_AMD64) || defined(_M_X64))) ||            \
     (defined(__i386) && (defined(__GNUC__) || defined(__SUNPRO_CC))) ||       \
     (defined(__x86_64) && (defined(__GNUC__) || defined(__SUNPRO_CC))) ||     \
     (defined(__sparc) && (defined(__GNUC__) || defined(__SUNPRO_CC))) ||      \