[clang] Add ARM64 support to armintr.h for MSVC compatibility

[mgrang]

Summary

This fixes compiling with headers from the Windows SDK for ARM64.

[mgrang]

Refer http://infocenter.arm.com/help/topic/com.arm.doc.ihi0053c/IHI0053C_acle_2_0.pdf for memory barriers.

[mstorsjo]

The Microsoft version of intrin.h includes a header named arm64intr.h (IIRC), I think it'd be better for compatibility if we also provided a file with the same name instead of reusing this one.

[compnerd]

Please split this out into arm64intr.h and include it from intrin.h under a #if defined(_M_ARM64) case before committing.

[mgrang]

Patch updated as per comments.

cfe/trunk/lib/Headers/CMakeLists.txt

 set(files
   adxintrin.h
   altivec.h
   ammintrin.h
   arm_acle.h
   armintr.h
+  arm64intr.h
   avx2intrin.h
   avx512bwintrin.h
   avx512cdintrin.h
   avx512vpopcntdqintrin.h
   avx512dqintrin.h
   avx512erintrin.h
   avx512fintrin.h
   avx512ifmaintrin.h

cfe/trunk/lib/Headers/arm64intr.h

+/*===---- arm64intr.h - ARM64 Windows intrinsics -------------------------------===
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+/* Only include this if we're compiling for the windows platform. */
+#ifndef _MSC_VER
+#include_next <arm64intr.h>
+#else
+
+#ifndef __ARM64INTR_H
+#define __ARM64INTR_H
+
+typedef enum
+{
+  _ARM64_BARRIER_SY    = 0xF,
+  _ARM64_BARRIER_ST    = 0xE,
+  _ARM64_BARRIER_LD    = 0xD,
+  _ARM64_BARRIER_ISH   = 0xB,
+  _ARM64_BARRIER_ISHST = 0xA,
+  _ARM64_BARRIER_ISHLD = 0x9,
+  _ARM64_BARRIER_NSH   = 0x7,
+  _ARM64_BARRIER_NSHST = 0x6,
+  _ARM64_BARRIER_NSHLD = 0x5,
+  _ARM64_BARRIER_OSH   = 0x3,
+  _ARM64_BARRIER_OSHST = 0x2,
+  _ARM64_BARRIER_OSHLD = 0x1
+} _ARM64INTR_BARRIER_TYPE;
+
+#endif /* __ARM64INTR_H */
+#endif /* _MSC_VER */

cfe/trunk/lib/Headers/intrin.h

 #if defined(__i386__) || defined(__x86_64__)
 #include <x86intrin.h>
 #endif
 
 #if defined(__arm__)
 #include <armintr.h>
 #endif
 
+#if defined(_M_ARM64)
+#include <arm64intr.h>
+#endif
+
 /* For the definition of jmp_buf. */
 #if __STDC_HOSTED__
 #include <setjmp.h>
 #endif
 
 /* Define the default attributes for the functions in this file. */
 #define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__))