Merge pull request #27 from crozone/msc-sse-detection

Added SSE version check for MSC

README.md

@@ -95,9 +95,12 @@ To build the project without all of the above instructions introduced with SSE2,
 
 `CFLAGS=-DNOSSE2 make`
 
-This flag is automatically enabled if the `__SSE__` flag is present but `__SSE2__` is absent.
+`NOSSE2` is automatically enabled if the `__SSE__` flag is present but `__SSE2__` is absent.
 This means `NOSSE2` shouldn't need to be manually specified when compiling on Clang or GCC on non-SSE2 processors.
 
+On MSC, `NOSSE2` is automatically enabled if the `_M_IX86_FP` flag is set to `1` (indicating SSE support, but no SSE2 support).
+MSC will set this by default for all x86 processors.
+
 #### 'Target specific option mismatch' error
 
 Some 32-bit versions of gcc (e.g. the version used in Ubuntu 14.04) may show the following error while compiling the PoC:

spectre.c

@@ -19,13 +19,20 @@
 #pragma optimize("gt",on)
 #else
 #include <x86intrin.h> /* for rdtsc, rdtscp, clflush */
+#endif /* ifdef _MSC_VER */
 
 /* Automatically detect if SSE2 is not available when SSE is advertized */
-#if defined(__SSE__) && !defined(__SSE2__)
+#ifdef _MSC_VER
+/* MSC */
+#if _M_IX86_FP==1
 #define NOSSE2
 #endif
-
+#else
+/* Not MSC */
+#if defined(__SSE__) && !defined(__SSE2__)
+#define NOSSE2
 #endif
+#endif /* ifdef _MSC_VER */
 
 #ifdef NOSSE2
 #define NORDTSCP