Bug 662765 - Respect _M_IX86_FP. r=jlebar

xpcom/glue/SSE.h

@@ -171,7 +171,18 @@
   #define MOZILLA_SSE_HAVE_CPUID_DETECTION
 #endif
 
-#if defined(_M_AMD64)
+#if defined(_M_IX86_FP)
+
+#if _M_IX86_FP >= 1
+  // It's ok to use SSE instructions based on the /arch option
+  #define MOZILLA_PRESUME_SSE
+#endif
+#if _M_IX86_FP >= 2
+  // It's ok to use SSE2 instructions based on the /arch option
+  #define MOZILLA_PRESUME_SSE2
+#endif
+
+#elif defined(_M_AMD64)
   // MSVC for AMD64 doesn't support MMX, so don't presume it here.
 
   // SSE is always available on AMD64.