ARM64: initial clang support commit.

This adds Clang support for the ARM64 backend. There are definitely
still some rough edges, so please bring up any issues you see with
this patch.

As with the LLVM commit though, we think it'll be more useful for
merging with AArch64 from within the tree.

llvm-svn: 205100

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 9a2076d95ae..1648c3bf852 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -244,6 +244,11 @@ public:
   llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, llvm::Value *allocPtr,
                                    CharUnits cookieSize) override;
 };
+
+class iOS64CXXABI : public ARMCXXABI {
+public:
+  iOS64CXXABI(CodeGen::CodeGenModule &CGM) : ARMCXXABI(CGM) {}
+};
 }
 
 CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) {
@@ -254,6 +259,9 @@ CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) {
   case TargetCXXABI::iOS:
     return new ARMCXXABI(CGM);
 
+  case TargetCXXABI::iOS64:
+    return new iOS64CXXABI(CGM);
+
   // Note that AArch64 uses the generic ItaniumCXXABI class since it doesn't
   // include the other 32-bit ARM oddities: constructor/destructor return values
   // and array cookies.
@@ -1415,6 +1423,13 @@ void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
   //         __cxa_guard_release (&obj_guard);
   //       }
   //     }
+
+    // ARM64 C++ ABI 3.2.2:
+    // This ABI instead only specifies the value bit 0 of the static guard
+    // variable; all other bits are platform defined. Bit 0 shall be 0 when the
+    // variable is not initialized and 1 when it is.
+    // FIXME: Reading one bit is no more efficient than reading one byte so
+    // the codegen is same as generic Itanium ABI.
   } else {
     // Load the first byte of the guard variable.
     llvm::LoadInst *LI =