[PATCH] D24330: Add some MS aliases for existing intrinsics

[David Majnemer via cfe-commits]

majnemer added inline comments.

================
Comment at: include/clang/Basic/BuiltinsX86.def:304
@@ -303,2 +303,3 @@
 TARGET_BUILTIN(__builtin_ia32_ldmxcsr, "vUi", "", "sse")
+TARGET_BUILTIN(_mm_setcsr, "vUi", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_stmxcsr, "Ui", "", "sse")
----------------
rnk wrote:
> Part of the idea behind the Intel *mmintrin.h headers is that they define symbols outside of the implementor's namespace. Users should be able to write code that uses these _mm_* names if they don't include those headers. Having this builtin always be available on x86 makes that impossible.
> 
> That said, I can see that winnt.h uses these directly, rather than including xmmintrin.h, so we need them to be builtins in MSVC mode, and it's annoying to have them sometimes be builtins and sometimes be functions.
We could have the header file use a pragma which turns the _mm intrinsics on along the same lines as `#pragma intrinsic`.  For MSVC compat, we could treat them as-if they were enabled by some similar mechanism.


https://reviews.llvm.org/D24330