mac: Add ARM64 support to swiftshader.

Bug: chromium:1098899
Change-Id: Iad5cd599e7e90f29249d0e4129ca1fe4a10d77c6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/46029
Presubmit-Ready: Nico Weber <thakis@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nico Weber <thakis@google.com>
diff --git a/third_party/llvm-7.0/configs/darwin/include/llvm/Config/config.h b/third_party/llvm-7.0/configs/darwin/include/llvm/Config/config.h
index 28c9098..26eb8f9 100644
--- a/third_party/llvm-7.0/configs/darwin/include/llvm/Config/config.h
+++ b/third_party/llvm-7.0/configs/darwin/include/llvm/Config/config.h
@@ -293,6 +293,8 @@
 /* Doesn't use `cmakedefine` because it is allowed to be empty. */
 #if defined(__x86_64__)
 #define LLVM_DEFAULT_TARGET_TRIPLE "x86_64-apple-darwin"
+#elif defined(__aarch64__)
+#define LLVM_DEFAULT_TARGET_TRIPLE "arm64-apple-darwin"
 #else
 #error "unknown architecture"
 #endif
diff --git a/third_party/llvm-7.0/configs/darwin/include/llvm/Config/llvm-config.h b/third_party/llvm-7.0/configs/darwin/include/llvm/Config/llvm-config.h
index 54d348b..e01e467 100644
--- a/third_party/llvm-7.0/configs/darwin/include/llvm/Config/llvm-config.h
+++ b/third_party/llvm-7.0/configs/darwin/include/llvm/Config/llvm-config.h
@@ -23,6 +23,8 @@
 /* Target triple LLVM will generate code for by default */
 #if defined(__x86_64__)
 #define LLVM_DEFAULT_TARGET_TRIPLE "x86_64-apple-darwin"
+#elif defined(__aarch64__)
+#define LLVM_DEFAULT_TARGET_TRIPLE "arm64-apple-darwin"
 #else
 #error "unknown architecture"
 #endif
@@ -36,6 +38,8 @@
 /* Host triple LLVM will be executed on */
 #if defined(__x86_64__)
 #define LLVM_HOST_TRIPLE "x86_64-apple-darwin"
+#elif defined(__aarch64__)
+#define LLVM_HOST_TRIPLE "arm64-apple-darwin"
 #else
 #error "unknown architecture"
 #endif