[X86] Add support for _MM_ALIGN16

[mkuper]

Summary

Both MSVC and ICC define this in xmmintrin.h, so, in terms of compatibility, I'd prefer to have it there in clang as well, even though it's MS-specific.

[echristo]

Couple of inline comments, otherwise LGTM.

-eric

test/CodeGen/ms-mm-align.c

1 ↗

(On Diff #31317)

Any chance of putting thi with the rest of the Intrin.h checks?

2 ↗

(On Diff #31317)

Shouldn't need -Oz.

[mkuper]

Thanks, Eric!

test/CodeGen/ms-mm-align.c

1 ↗

(On Diff #31317)

I've originally wanted to put it in ms-intinsics.c, but it fails for the "-triple thumbv7--windows" test (as it should - this is an x86-only macro).
If you have a different test in mind, I'll move it there.

2 ↗

(On Diff #31317)

Copied that from ms-intrinsics.c as well. Will remove.

[echristo]

test/CodeGen/ms-mm-align.c

1 ↗

(On Diff #31317)

No that seems reasonable.

2 ↗

(On Diff #31317)

Feel free to remove it from the other file as well.

cfe/trunk/lib/Headers/xmmintrin.h

 }
 
 static __inline__ int __DEFAULT_FN_ATTRS
 _mm_movemask_ps(__m128 __a)
 {
   return __builtin_ia32_movmskps(__a);
 }
 
+
+#ifdef _MSC_VER
+#define _MM_ALIGN16 __declspec(align(16))
+#endif
+
 #define _MM_SHUFFLE(z, y, x, w) (((z) << 6) | ((y) << 4) | ((x) << 2) | (w))
 
 #define _MM_EXCEPT_INVALID    (0x0001)
 #define _MM_EXCEPT_DENORM     (0x0002)
 #define _MM_EXCEPT_DIV_ZERO   (0x0004)
 #define _MM_EXCEPT_OVERFLOW   (0x0008)
 #define _MM_EXCEPT_UNDERFLOW  (0x0010)
 #define _MM_EXCEPT_INEXACT    (0x0020)

cfe/trunk/test/CodeGen/ms-mm-align.c

+// RUN: %clang_cc1 -ffreestanding -fms-extensions -fms-compatibility -fms-compatibility-version=17.00 \
+// RUN:         -triple i686--windows -emit-llvm %s -o - \
+// RUN:         | FileCheck %s -check-prefix CHECK
+
+// Intrin.h needs size_t, but -ffreestanding prevents us from getting it from
+// stddef.h.  Work around it with this typedef.
+typedef __SIZE_TYPE__ size_t;
+#include <Intrin.h>
+
+void capture_ptr(int* i);
+void test_mm_align16(int p) {
+  _MM_ALIGN16 int i;
+  capture_ptr(&i);
+}
+
+// CHECK: alloca i32, align 16