Define __SSE__ when compiling with -msse
The hashable package needs to know if GHC was invoked with -msse4.1 so it can call out to faster C code in that case. I'd like to propose that GHC provides the following defines when running the preprocessor:
## If SSE is turned on at all: #define __SSE__ 1 ## Only with -msse2 and up: #define __SSE2__ 1 ## Only with -msse4.1 and up: #define __SSE4_1__ 1
This behavior is consistent with GCC.
Note that on some platforms SSE2 might be enabled by default and so should the defines.