[AArch64] Add support for __builtin_ms_va_list on aarch64

[mstorsjo]

Summary

Move builtins from the x86 specific scope into the global scope. Their use is still limited to x86_64 and aarch64 though.

This allows wine on aarch64 to properly handle variadic functions.

This depends on D34474 for llvm.

[mstorsjo]

Did a minor adjustment, to make sure a plain va_arg produces the right kind of output, when targeting windows directly (while the rest of the patch mostly is about supporting the MS ABI while targeting a different OS).

[mstorsjo]

Split the patch into two; one for generic handling of va_arg for win/arm64, and one for using the same functionality while targeting other OSes (i.e. for wine) via the __builtin_ms_* intrinsics.

[mstorsjo]

Added test cases, a minor tweak to semantic error handling, removed the RFC tag, removed the reference to the clang prerequisite that now is committed.

[rnk]

include/clang/Basic/BuiltinsAArch64.def

65 ↗

(On Diff #106489)

I strongly suspect that Microsoft will never adopt a varargs calling convention that uses a complex, non-char* va_list.

I'm starting to think we should move this to the generic builtin list and make it available everywhere. The semantics are that you can only use __builtin_ms_va_start in ms_abi functions. It always produces a char*-style va_list.

include/clang/Basic/Specifiers.h

239

I think we might prefer to make this non-x86_64 specific. I suspect that this pattern will arise again on ARM32 if anyone goes back there in seriousness. We'll probably want sysv_abi as well as ms_abi, and all the logic should be independent of the ISA: ms_abi is a no-op when the target OS is already Windows, and sysv_abi is a no-op when the target OS isn't Windows.

lib/CodeGen/CGBuiltin.cpp

5303

If we made __builtin_ms_va_start generic, that would also eliminate this duplicate code.

lib/CodeGen/CGCall.cpp

221–222

Unifying the ms_abi CCs would remove the need for this.

lib/Sema/SemaChecking.cpp

3620

Oh dear, how can we keep this simple. I think unifying the CC's would improve things.

lib/Sema/SemaDeclAttr.cpp

4284

Ditto

[mstorsjo]

include/clang/Basic/BuiltinsAArch64.def

65 ↗

(On Diff #106489)

Yes, that seems probable.

I'm a little weary about making this available anywhere though, since it is coupled with the x86_64/aarch64 specific calling convention for lowering va_start, and there we only support it specifically on those two arches.

include/clang/Basic/Specifiers.h

239

FWIW, we already support ARM32 for windows, and there, varargs are identical to other platforms.

Extending this to all platforms probably also makes sense (although I'm a little weary about how it would work for signaling down to the LLVM IR).

[rnk]

include/clang/Basic/BuiltinsAArch64.def

65 ↗

(On Diff #106489)

We should have Sema checking that rejects it when not targeting x64 or aarch64. Ultimately the codegen is shared and simple: just call llvm.va.start.

[mstorsjo]

Initial attempt at unifying the use of __builtin_ms_va_list and calling conventions between x86_64 and aarch64. This goes with the current (un-unified) version of D34474.

I only hooked up attribute((ms_abi)) on aarch64, I didn't hook up sysv_abi yet, because it's not obvious what it should map to, since aarch64 has got two other calling conventions in addition to the win64 one; standard AAPCS (for ELF systems) and the darwin modification of AAPCS. Since that's not directly needed for the wine usecase, I'm omitting that for now.

[mstorsjo]

Updated for the new version of D34474.

[mstorsjo]

Reid, with D34474 approved, does this look like what you had in mind?

[rnk]

Thanks, looks great!

include/clang-c/Index.h

enum CXCallingConv {
   CXCallingConv_X86StdCall = 2,
   CXCallingConv_X86FastCall = 3,
   CXCallingConv_X86ThisCall = 4,
   CXCallingConv_X86Pascal = 5,
   CXCallingConv_AAPCS = 6,
   CXCallingConv_AAPCS_VFP = 7,
   CXCallingConv_X86RegCall = 8,
   CXCallingConv_IntelOclBicc = 9,
-  CXCallingConv_X86_64Win64 = 10,
+  CXCallingConv_Win64 = 10,
   CXCallingConv_X86_64SysV = 11,
   CXCallingConv_X86VectorCall = 12,
   CXCallingConv_Swift = 13,
   CXCallingConv_PreserveMost = 14,
   CXCallingConv_PreserveAll = 15,
 
   CXCallingConv_Invalid = 100,
   CXCallingConv_Unexposed = 200

include/clang/Basic/Builtins.def

 
 // Builtins for os_log/os_trace
 BUILTIN(__builtin_os_log_format_buffer_size, "zcC*.", "p:0:nut")
 BUILTIN(__builtin_os_log_format, "v*v*cC*.", "p:0:nt")
 
 // Builtins for XRay
 BUILTIN(__xray_customevent, "vcC*z", "")
 
+// Win64-compatible va_list functions
+BUILTIN(__builtin_ms_va_start, "vc*&.", "nt")
+BUILTIN(__builtin_ms_va_end, "vc*&", "n")
+BUILTIN(__builtin_ms_va_copy, "vc*&c*&", "n")
+
 #undef BUILTIN
 #undef LIBBUILTIN
 #undef LANGBUILTIN

include/clang/Basic/BuiltinsX86.def

 
 // FIXME: Are these nothrow/const?
 
 // Miscellaneous builtin for checking x86 cpu features.
 // TODO: Make this somewhat generic so that other backends
 // can use it?
 BUILTIN(__builtin_cpu_supports, "bcC*", "nc")
 
-// Win64-compatible va_list functions
-BUILTIN(__builtin_ms_va_start, "vc*&.", "nt")
-BUILTIN(__builtin_ms_va_end, "vc*&", "n")
-BUILTIN(__builtin_ms_va_copy, "vc*&c*&", "n")
-
 // Undefined Values
 //
 TARGET_BUILTIN(__builtin_ia32_undef128, "V2d", "nc", "")
 TARGET_BUILTIN(__builtin_ia32_undef256, "V4d", "nc", "")
 TARGET_BUILTIN(__builtin_ia32_undef512, "V8d", "nc", "")
 
 // FLAGS
 //

include/clang/Basic/DiagnosticSemaKinds.td

 def note_neon_vector_initializer_non_portable_q : Note<
   "consider using vld1q_%0%1() to initialize a vector from memory, or "
   "vcombine_%0%1(vcreate_%0%1(), vcreate_%0%1()) to initialize from integer "
   "constants">;
 def err_systemz_invalid_tabort_code : Error<
   "invalid transaction abort code">;
 def err_64_bit_builtin_32_bit_tgt : Error<
   "this builtin is only available on 64-bit targets">;
+def err_builtin_x64_aarch64_only : Error<
+  "this builtin is only available on x86-64 and aarch64 targets">;
 def err_ppc_builtin_only_on_pwr7 : Error<
   "this builtin is only valid on POWER7 or later CPUs">;
-def err_x86_builtin_64_only : Error<
-  "this builtin is only available on x86-64 targets">;
 def err_x86_builtin_invalid_rounding : Error<
   "invalid rounding argument">;
 def err_x86_builtin_invalid_scale : Error<
   "scale argument must be 1, 2, 4, or 8">;
 
 def err_builtin_longjmp_unsupported : Error<
   "__builtin_longjmp is not supported for the current target">;
 def err_builtin_setjmp_unsupported : Error<

include/clang/Basic/Specifiers.h

#include "clang/Basic/OpenCLImageTypes.def"
   /// \brief CallingConv - Specifies the calling convention that a function uses.
   enum CallingConv {
     CC_C,           // __attribute__((cdecl))
     CC_X86StdCall,  // __attribute__((stdcall))
     CC_X86FastCall, // __attribute__((fastcall))
     CC_X86ThisCall, // __attribute__((thiscall))
     CC_X86VectorCall, // __attribute__((vectorcall))
     CC_X86Pascal,   // __attribute__((pascal))
-    CC_X86_64Win64, // __attribute__((ms_abi))
+    CC_Win64,       // __attribute__((ms_abi))
     CC_X86_64SysV,  // __attribute__((sysv_abi))
     CC_X86RegCall, // __attribute__((regcall))
     CC_AAPCS,       // __attribute__((pcs("aapcs")))
     CC_AAPCS_VFP,   // __attribute__((pcs("aapcs-vfp")))
     CC_IntelOclBicc, // __attribute__((intel_ocl_bicc))
     CC_SpirFunction, // default for OpenCL functions on SPIR target
     CC_OpenCLKernel, // inferred for OpenCL kernels
     CC_Swift,        // __attribute__((swiftcall))

lib/AST/ItaniumMangle.cpp

StringRef CXXNameMangler::getCallingConvQualifierName(CallingConv CC) {
   case CC_C:
     return "";
 
   case CC_X86StdCall:
   case CC_X86FastCall:
   case CC_X86ThisCall:
   case CC_X86VectorCall:
   case CC_X86Pascal:
-  case CC_X86_64Win64:
+  case CC_Win64:
   case CC_X86_64SysV:
   case CC_X86RegCall:
   case CC_AAPCS:
   case CC_AAPCS_VFP:
   case CC_IntelOclBicc:
   case CC_SpirFunction:
   case CC_OpenCLKernel:
   case CC_PreserveMost:

lib/AST/MicrosoftMangle.cpp

void MicrosoftCXXNameMangler::mangleCallingConvention(CallingConv CC) {
   // (*cough*Win16*cough*) when functions were declared for export with
   // that keyword. (It didn't actually export them, it just made them so
   // that they could be in a DLL and somebody from another module could call
   // them.)
 
   switch (CC) {
     default:
       llvm_unreachable("Unsupported CC for mangling");
-    case CC_X86_64Win64:
+    case CC_Win64:
     case CC_X86_64SysV:
     case CC_C: Out << 'A'; break;
     case CC_X86Pascal: Out << 'C'; break;
     case CC_X86ThisCall: Out << 'E'; break;
     case CC_X86StdCall: Out << 'G'; break;
     case CC_X86FastCall: Out << 'I'; break;
     case CC_X86VectorCall: Out << 'Q'; break;
     case CC_X86RegCall: Out << 'w'; break;

lib/AST/Type.cpp

 StringRef FunctionType::getNameForCallConv(CallingConv CC) {
   switch (CC) {
   case CC_C: return "cdecl";
   case CC_X86StdCall: return "stdcall";
   case CC_X86FastCall: return "fastcall";
   case CC_X86ThisCall: return "thiscall";
   case CC_X86Pascal: return "pascal";
   case CC_X86VectorCall: return "vectorcall";
-  case CC_X86_64Win64: return "ms_abi";
+  case CC_Win64: return "ms_abi";
   case CC_X86_64SysV: return "sysv_abi";
   case CC_X86RegCall : return "regcall";
   case CC_AAPCS: return "aapcs";
   case CC_AAPCS_VFP: return "aapcs-vfp";
   case CC_IntelOclBicc: return "intel_ocl_bicc";
   case CC_SpirFunction: return "spir_function";
   case CC_OpenCLKernel: return "opencl_kernel";
   case CC_Swift: return "swiftcall";

lib/AST/TypePrinter.cpp

case CC_AAPCS:
       OS << " __attribute__((pcs(\"aapcs\")))";
       break;
     case CC_AAPCS_VFP:
       OS << " __attribute__((pcs(\"aapcs-vfp\")))";
       break;
     case CC_IntelOclBicc:
       OS << " __attribute__((intel_ocl_bicc))";
       break;
-    case CC_X86_64Win64:
+    case CC_Win64:
       OS << " __attribute__((ms_abi))";
       break;
     case CC_X86_64SysV:
       OS << " __attribute__((sysv_abi))";
       break;
     case CC_X86RegCall:
       OS << " __attribute__((regcall))";
       break;

lib/Basic/Targets.cpp

public:
   }
 
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
     switch (CC) {
     case CC_C:
     case CC_Swift:
     case CC_X86VectorCall:
     case CC_IntelOclBicc:
-    case CC_X86_64Win64:
+    case CC_Win64:
     case CC_PreserveMost:
     case CC_PreserveAll:
     case CC_X86RegCall:
     case CC_OpenCLKernel:
       return CCCR_OK;
     default:
       return CCCR_Warning;
     }
AArch64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
     LongWidth = LongAlign = PointerWidth = PointerAlign = 64;
     MaxVectorAlign = 128;
     MaxAtomicInlineWidth = 128;
     MaxAtomicPromoteWidth = 128;
 
     LongDoubleWidth = LongDoubleAlign = SuitableAlign = 128;
     LongDoubleFormat = &llvm::APFloat::IEEEquad();
 
+    // Make __builtin_ms_va_list available.
+    HasBuiltinMSVaList = true;
+
     // {} in inline assembly are neon specifiers, not assembly variant
     // specifiers.
     NoAsmVariants = true;
 
     // AAPCS gives rules for bitfields. 7.1.7 says: "The container type
     // contributes to the alignment of the containing aggregate in the same way
     // a plain (non bit-field) member of that type would, without exception for
     // zero-sized or anonymous bit-fields."
public:
 
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
     switch (CC) {
     case CC_C:
     case CC_Swift:
     case CC_PreserveMost:
     case CC_PreserveAll:
     case CC_OpenCLKernel:
+    case CC_Win64:
       return CCCR_OK;
     default:
       return CCCR_Warning;
     }
   }
 
   bool isCLZForZeroUndef() const override { return false; }
 

lib/CodeGen/CGBuiltin.cpp

if (PTy0 != Arg0Val->getType()) {
         Arg0Val = Builder.CreatePointerCast(Arg0Val, PTy0);
     }
     auto Arg1 = EmitScalarExpr(E->getArg(1));
     auto PTy1 = FTy->getParamType(1);
     if (PTy1 != Arg1->getType())
       Arg1 = Builder.CreateTruncOrBitCast(Arg1, PTy1);
     return RValue::get(Builder.CreateCall(F, {Arg0Val, Arg1}));
   }
+
+  case Builtin::BI__builtin_ms_va_start:
+  case Builtin::BI__builtin_ms_va_end:
+    return RValue::get(
+        EmitVAStartEnd(EmitMSVAListRef(E->getArg(0)).getPointer(),
+                       BuiltinID == Builtin::BI__builtin_ms_va_start));
+
+  case Builtin::BI__builtin_ms_va_copy: {
+    // Lower this manually. We can't reliably determine whether or not any
+    // given va_copy() is for a Win64 va_list from the calling convention
+    // alone, because it's legal to do this from a System V ABI function.
+    // With opaque pointer types, we won't have enough information in LLVM
+    // IR to determine this from the argument types, either. Best to do it
+    // now, while we have enough information.
+    Address DestAddr = EmitMSVAListRef(E->getArg(0));
+    Address SrcAddr = EmitMSVAListRef(E->getArg(1));
+
+    llvm::Type *BPP = Int8PtrPtrTy;
+
+    DestAddr = Address(Builder.CreateBitCast(DestAddr.getPointer(), BPP, "cp"),
+                       DestAddr.getAlignment());
+    SrcAddr = Address(Builder.CreateBitCast(SrcAddr.getPointer(), BPP, "ap"),
+                      SrcAddr.getAlignment());
+
+    Value *ArgPtr = Builder.CreateLoad(SrcAddr, "ap.val");
+    return RValue::get(Builder.CreateStore(ArgPtr, DestAddr));
+  }
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit
   // the call using the normal call path, but using the unmangled
   // version of the function name.
   if (getContext().BuiltinInfo.isLibFunction(BuiltinID))
     return emitLibraryCall(*this, FD, E,
                            CGM.getBuiltinLibFunction(FD, BuiltinID));
Value *CodeGenFunction::vectorWrapScalar16(Value *Op) {
   Value *V = UndefValue::get(VTy);
   llvm::Constant *CI = ConstantInt::get(SizeTy, 0);
   Op = Builder.CreateInsertElement(V, Op, CI);
   return Op;
 }
 
 Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
                                                const CallExpr *E) {
   unsigned HintID = static_cast<unsigned>(-1);
   switch (BuiltinID) {
   default: break;
   case AArch64::BI__builtin_arm_nop:
     HintID = 0;
     break;
   case AArch64::BI__builtin_arm_yield:
     HintID = 1;
     break;
static Value *EmitX86SExtMask(CodeGenFunction &CGF, Value *Op,
                               llvm::Type *DstTy) {
   unsigned NumberOfElements = DstTy->getVectorNumElements();
   Value *Mask = getMaskVecValue(CGF, Op, NumberOfElements);
   return CGF.Builder.CreateSExt(Mask, DstTy, "vpmovm2");
 }
 
 Value *CodeGenFunction::EmitX86BuiltinExpr(unsigned BuiltinID,
                                            const CallExpr *E) {
-  if (BuiltinID == X86::BI__builtin_ms_va_start ||
-      BuiltinID == X86::BI__builtin_ms_va_end)
-    return EmitVAStartEnd(EmitMSVAListRef(E->getArg(0)).getPointer(),
-                          BuiltinID == X86::BI__builtin_ms_va_start);
-  if (BuiltinID == X86::BI__builtin_ms_va_copy) {
-    // Lower this manually. We can't reliably determine whether or not any
-    // given va_copy() is for a Win64 va_list from the calling convention
-    // alone, because it's legal to do this from a System V ABI function.
-    // With opaque pointer types, we won't have enough information in LLVM
-    // IR to determine this from the argument types, either. Best to do it
-    // now, while we have enough information.
-    Address DestAddr = EmitMSVAListRef(E->getArg(0));
-    Address SrcAddr = EmitMSVAListRef(E->getArg(1));
-
-    llvm::Type *BPP = Int8PtrPtrTy;
-
-    DestAddr = Address(Builder.CreateBitCast(DestAddr.getPointer(), BPP, "cp"),
-                       DestAddr.getAlignment());
-    SrcAddr = Address(Builder.CreateBitCast(SrcAddr.getPointer(), BPP, "ap"),
-                      SrcAddr.getAlignment());
-
-    Value *ArgPtr = Builder.CreateLoad(SrcAddr, "ap.val");
-    return Builder.CreateStore(ArgPtr, DestAddr);
-  }
-
   SmallVector<Value*, 4> Ops;
 
   // Find out if any arguments are required to be integer constant expressions.
   unsigned ICEArguments = 0;
   ASTContext::GetBuiltinTypeError Error;
   getContext().GetBuiltinType(BuiltinID, Error, &ICEArguments);
   assert(Error == ASTContext::GE_None && "Should not codegen an error");
 

lib/CodeGen/CGCall.cpp

 
 unsigned CodeGenTypes::ClangCallConvToLLVMCallConv(CallingConv CC) {
   switch (CC) {
   default: return llvm::CallingConv::C;
   case CC_X86StdCall: return llvm::CallingConv::X86_StdCall;
   case CC_X86FastCall: return llvm::CallingConv::X86_FastCall;
   case CC_X86RegCall: return llvm::CallingConv::X86_RegCall;
   case CC_X86ThisCall: return llvm::CallingConv::X86_ThisCall;
-  case CC_X86_64Win64: return llvm::CallingConv::X86_64_Win64;
+  case CC_Win64: return llvm::CallingConv::Win64;
   case CC_X86_64SysV: return llvm::CallingConv::X86_64_SysV;
   case CC_AAPCS: return llvm::CallingConv::ARM_AAPCS;
   case CC_AAPCS_VFP: return llvm::CallingConv::ARM_AAPCS_VFP;
   case CC_IntelOclBicc: return llvm::CallingConv::Intel_OCL_BI;
   // TODO: Add support for __pascal to LLVM.
   case CC_X86Pascal: return llvm::CallingConv::C;
   // TODO: Add support for __vectorcall to LLVM.
   case CC_X86VectorCall: return llvm::CallingConv::X86_VectorCall;
static CallingConv getCallingConventionForDecl(const Decl *D, bool IsWindows) {
 
   if (PcsAttr *PCS = D->getAttr<PcsAttr>())
     return (PCS->getPCS() == PcsAttr::AAPCS ? CC_AAPCS : CC_AAPCS_VFP);
 
   if (D->hasAttr<IntelOclBiccAttr>())
     return CC_IntelOclBicc;
 
   if (D->hasAttr<MSABIAttr>())
-    return IsWindows ? CC_C : CC_X86_64Win64;
+    return IsWindows ? CC_C : CC_Win64;
 
   if (D->hasAttr<SysVABIAttr>())
     return IsWindows ? CC_X86_64SysV : CC_C;
 
   if (D->hasAttr<PreserveMostAttr>())
     return CC_PreserveMost;
 
   if (D->hasAttr<PreserveAllAttr>())
     return CC_PreserveAll;

lib/CodeGen/CGDebugInfo.cpp

static unsigned getDwarfCC(CallingConv CC) {
   case CC_X86ThisCall:
     return llvm::dwarf::DW_CC_BORLAND_thiscall;
   case CC_X86VectorCall:
     return llvm::dwarf::DW_CC_LLVM_vectorcall;
   case CC_X86Pascal:
     return llvm::dwarf::DW_CC_BORLAND_pascal;
 
   // FIXME: Create new DW_CC_ codes for these calling conventions.
-  case CC_X86_64Win64:
+  case CC_Win64:
   case CC_X86_64SysV:
   case CC_AAPCS:
   case CC_AAPCS_VFP:
   case CC_IntelOclBicc:
   case CC_SpirFunction:
   case CC_OpenCLKernel:
   case CC_Swift:
   case CC_PreserveMost:

lib/Sema/SemaChecking.cpp

Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
   
   switch (BuiltinID) {
   case Builtin::BI__builtin___CFStringMakeConstantString:
     assert(TheCall->getNumArgs() == 1 &&
            "Wrong # arguments to builtin CFStringMakeConstantString");
     if (CheckObjCString(TheCall->getArg(0)))
       return ExprError();
     break;
+  case Builtin::BI__builtin_ms_va_start:
   case Builtin::BI__builtin_stdarg_start:
   case Builtin::BI__builtin_va_start:
     if (SemaBuiltinVAStart(BuiltinID, TheCall))
       return ExprError();
     break;
   case Builtin::BI__va_start: {
     switch (Context.getTargetInfo().getTriple().getArch()) {
     case llvm::Triple::arm:
bool Sema::CheckX86BuiltinGatherScatterScale(unsigned BuiltinID,
   return Diag(TheCall->getLocStart(), diag::err_x86_builtin_invalid_scale)
     << Arg->getSourceRange();
 }
 
 bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   if (BuiltinID == X86::BI__builtin_cpu_supports)
     return SemaBuiltinCpuSupports(*this, TheCall);
 
-  if (BuiltinID == X86::BI__builtin_ms_va_start)
-    return SemaBuiltinVAStart(BuiltinID, TheCall);
-
   // If the intrinsic has rounding or SAE make sure its valid.
   if (CheckX86BuiltinRoundingOrSAE(BuiltinID, TheCall))
     return true;
 
   // If the intrinsic has a gather/scatter scale immediate make sure its valid.
   if (CheckX86BuiltinGatherScatterScale(BuiltinID, TheCall))
     return true;
 
ExprResult Sema::CheckOSLogFormatStringArg(Expr *Arg) {
   InitializedEntity Entity =
       InitializedEntity::InitializeParameter(Context, ResultTy, false);
   Result = PerformCopyInitialization(Entity, SourceLocation(), Result);
   return Result;
 }
 
 /// Check that the user is calling the appropriate va_start builtin for the
 /// target and calling convention.
 static bool checkVAStartABI(Sema &S, unsigned BuiltinID, Expr *Fn) {
   const llvm::Triple &TT = S.Context.getTargetInfo().getTriple();
   bool IsX64 = TT.getArch() == llvm::Triple::x86_64;
+  bool IsAArch64 = TT.getArch() == llvm::Triple::aarch64;
   bool IsWindows = TT.isOSWindows();
-  bool IsMSVAStart = BuiltinID == X86::BI__builtin_ms_va_start;
-  if (IsX64) {
+  bool IsMSVAStart = BuiltinID == Builtin::BI__builtin_ms_va_start;
+  if (IsX64 || IsAArch64) {
     clang::CallingConv CC = CC_C;
     if (const FunctionDecl *FD = S.getCurFunctionDecl())
       CC = FD->getType()->getAs<FunctionType>()->getCallConv();
     if (IsMSVAStart) {
       // Don't allow this in System V ABI functions.
-      if (CC == CC_X86_64SysV || (!IsWindows && CC != CC_X86_64Win64))
+      if (CC == CC_X86_64SysV || (!IsWindows && CC != CC_Win64))
         return S.Diag(Fn->getLocStart(),
                       diag::err_ms_va_start_used_in_sysv_function);
     } else {
-      // On x86-64 Unix, don't allow this in Win64 ABI functions.
+      // On x86-64/AArch64 Unix, don't allow this in Win64 ABI functions.
       // On x64 Windows, don't allow this in System V ABI functions.
       // (Yes, that means there's no corresponding way to support variadic
       // System V ABI functions on Windows.)
       if ((IsWindows && CC == CC_X86_64SysV) ||
-          (!IsWindows && CC == CC_X86_64Win64))
+          (!IsWindows && CC == CC_Win64))
         return S.Diag(Fn->getLocStart(),
                       diag::err_va_start_used_in_wrong_abi_function)
                << !IsWindows;
     }
     return false;
   }
 
   if (IsMSVAStart)
-    return S.Diag(Fn->getLocStart(), diag::err_x86_builtin_64_only);
+    return S.Diag(Fn->getLocStart(), diag::err_builtin_x64_aarch64_only);
   return false;
 }
 
 static bool checkVAStartIsInVariadicFunction(Sema &S, Expr *Fn,
                                              ParmVarDecl **LastParam = nullptr) {
   // Determine whether the current function, block, or obj-c method is variadic
   // and get its parameter list.
   bool IsVariadic = false;

lib/Sema/SemaDeclAttr.cpp

bool Sema::CheckCallingConvAttr(const AttributeList &attr, CallingConv &CC,
   case AttributeList::AT_StdCall: CC = CC_X86StdCall; break;
   case AttributeList::AT_ThisCall: CC = CC_X86ThisCall; break;
   case AttributeList::AT_Pascal: CC = CC_X86Pascal; break;
   case AttributeList::AT_SwiftCall: CC = CC_Swift; break;
   case AttributeList::AT_VectorCall: CC = CC_X86VectorCall; break;
   case AttributeList::AT_RegCall: CC = CC_X86RegCall; break;
   case AttributeList::AT_MSABI:
     CC = Context.getTargetInfo().getTriple().isOSWindows() ? CC_C :
-                                                             CC_X86_64Win64;
+                                                             CC_Win64;
     break;
   case AttributeList::AT_SysVABI:
     CC = Context.getTargetInfo().getTriple().isOSWindows() ? CC_X86_64SysV :
                                                              CC_C;
     break;
   case AttributeList::AT_Pcs: {
     StringRef StrRef;
     if (!checkStringLiteralArgumentAttr(attr, 0, StrRef)) {
       attr.setInvalid();

test/CodeGen/ms_abi.c

 // WIN64: %[[STRUCT_FOO:.*]] = type { i32, float, i8 }
 
 void __attribute__((ms_abi)) f1(void);
 void __attribute__((sysv_abi)) f2(void);
 void f3(void) {
   // FREEBSD-LABEL: define void @f3()
   // WIN64-LABEL: define void @f3()
   f1();
-  // FREEBSD: call x86_64_win64cc void @f1()
+  // FREEBSD: call win64cc void @f1()
   // WIN64: call void @f1()
   f2();
   // FREEBSD: call void @f2()
   // WIN64: call x86_64_sysvcc void @f2()
 }
-// FREEBSD: declare x86_64_win64cc void @f1()
+// FREEBSD: declare win64cc void @f1()
 // FREEBSD: declare void @f2()
 // WIN64: declare void @f1()
 // WIN64: declare x86_64_sysvcc void @f2()
 
 // Win64 ABI varargs
 void __attribute__((ms_abi)) f4(int a, ...) {
-  // FREEBSD-LABEL: define x86_64_win64cc void @f4
+  // FREEBSD-LABEL: define win64cc void @f4
   // WIN64-LABEL: define void @f4
   __builtin_ms_va_list ap;
   __builtin_ms_va_start(ap, a);
   // FREEBSD: %[[AP:.*]] = alloca i8*
   // FREEBSD: call void @llvm.va_start
   // WIN64: %[[AP:.*]] = alloca i8*
   // WIN64: call void @llvm.va_start
   int b = __builtin_va_arg(ap, int);

test/CodeGen/ms_abi_aarch64.c

+// RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm < %s | FileCheck -check-prefix=LINUX %s
+// RUN: %clang_cc1 -triple aarch64-pc-win32 -emit-llvm < %s | FileCheck -check-prefix=WIN64 %s
+
+void __attribute__((ms_abi)) f1(void);
+void f2(void);
+void f3(void) {
+  // LINUX-LABEL: define void @f3()
+  // WIN64-LABEL: define void @f3()
+  f1();
+  // LINUX: call win64cc void @f1()
+  // WIN64: call void @f1()
+  f2();
+  // LINUX: call void @f2()
+  // WIN64: call void @f2()
+}
+// LINUX: declare win64cc void @f1()
+// LINUX: declare void @f2()
+// WIN64: declare void @f1()
+// WIN64: declare void @f2()
+
+// Win64 ABI varargs
+void __attribute__((ms_abi)) f4(int a, ...) {
+  // LINUX-LABEL: define win64cc void @f4
+  // WIN64-LABEL: define void @f4
+  __builtin_ms_va_list ap;
+  __builtin_ms_va_start(ap, a);
+  // LINUX: %[[AP:.*]] = alloca i8*
+  // LINUX: call void @llvm.va_start
+  // WIN64: %[[AP:.*]] = alloca i8*
+  // WIN64: call void @llvm.va_start
+  int b = __builtin_va_arg(ap, int);
+  // LINUX: %[[AP_CUR:.*]] = load i8*, i8** %[[AP]]
+  // LINUX-NEXT: %[[AP_NEXT:.*]] = getelementptr inbounds i8, i8* %[[AP_CUR]], i64 8
+  // LINUX-NEXT: store i8* %[[AP_NEXT]], i8** %[[AP]]
+  // LINUX-NEXT: bitcast i8* %[[AP_CUR]] to i32*
+  // WIN64: %[[AP_CUR:.*]] = load i8*, i8** %[[AP]]
+  // WIN64-NEXT: %[[AP_NEXT:.*]] = getelementptr inbounds i8, i8* %[[AP_CUR]], i64 8
+  // WIN64-NEXT: store i8* %[[AP_NEXT]], i8** %[[AP]]
+  // WIN64-NEXT: bitcast i8* %[[AP_CUR]] to i32*
+  __builtin_ms_va_list ap2;
+  __builtin_ms_va_copy(ap2, ap);
+  // LINUX: %[[AP_VAL:.*]] = load i8*, i8** %[[AP]]
+  // LINUX-NEXT: store i8* %[[AP_VAL]], i8** %[[AP2:.*]]
+  // WIN64: %[[AP_VAL:.*]] = load i8*, i8** %[[AP]]
+  // WIN64-NEXT: store i8* %[[AP_VAL]], i8** %[[AP2:.*]]
+  __builtin_ms_va_end(ap);
+  // LINUX: call void @llvm.va_end
+  // WIN64: call void @llvm.va_end
+}
+
+// Let's verify that normal va_lists work right on Win64, too.
+void f5(int a, ...) {
+  // WIN64-LABEL: define void @f5
+  __builtin_va_list ap;
+  __builtin_va_start(ap, a);
+  // WIN64: %[[AP:.*]] = alloca i8*
+  // WIN64: call void @llvm.va_start
+  int b = __builtin_va_arg(ap, int);
+  // WIN64: %[[AP_CUR:.*]] = load i8*, i8** %[[AP]]
+  // WIN64-NEXT: %[[AP_NEXT:.*]] = getelementptr inbounds i8, i8* %[[AP_CUR]], i64 8
+  // WIN64-NEXT: store i8* %[[AP_NEXT]], i8** %[[AP]]
+  // WIN64-NEXT: bitcast i8* %[[AP_CUR]] to i32*
+  __builtin_va_list ap2;
+  __builtin_va_copy(ap2, ap);
+  // WIN64: call void @llvm.va_copy
+  __builtin_va_end(ap);
+  // WIN64: call void @llvm.va_end
+}

test/CodeGenObjC/attr-callconv.m

 // RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm -o - %s | FileCheck %s
 
 @interface Test
 - (void)test;
 @end
 
 @implementation Test
 - (void)test __attribute__((stdcall)) {}
     // CHECK: define{{.*}}x86_stdcallcc{{.*}}Test test
     
 - (void)test2 __attribute__((ms_abi)) {}
-    // CHECK: define{{.*}}x86_64_win64cc{{.*}}Test test2
+    // CHECK: define{{.*}}win64cc{{.*}}Test test2
 @end

test/Sema/varargs-aarch64.c

+// RUN: %clang_cc1 -fsyntax-only -verify %s -triple aarch64-linux-gnu
+
+void f1(int a, ...) {
+  __builtin_ms_va_list ap;
+  __builtin_ms_va_start(ap, a); // expected-error {{'__builtin_ms_va_start' used in System V ABI function}}
+}
+
+void __attribute__((ms_abi)) f2(int a, ...) {
+  __builtin_va_list ap;
+  __builtin_va_start(ap, a); // expected-error {{'va_start' used in Win64 ABI function}}
+}

test/Sema/varargs-x86-32.c

 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple i386-apple-darwin9
 
 void foo(int a, ...) {
-  __builtin_ms_va_start((void *)0, a); // expected-error {{this builtin is only available on x86-64 targets}}
+  __builtin_ms_va_start((void *)0, a); // expected-error {{this builtin is only available on x86-64 and aarch64 targets}}
 }

tools/libclang/CXType.cpp

#define TCALLINGCONV(X) case CC_##X: return CXCallingConv_##X
     switch (FD->getCallConv()) {
       TCALLINGCONV(C);
       TCALLINGCONV(X86StdCall);
       TCALLINGCONV(X86FastCall);
       TCALLINGCONV(X86ThisCall);
       TCALLINGCONV(X86Pascal);
       TCALLINGCONV(X86RegCall);
       TCALLINGCONV(X86VectorCall);
-      TCALLINGCONV(X86_64Win64);
+      TCALLINGCONV(Win64);
       TCALLINGCONV(X86_64SysV);
       TCALLINGCONV(AAPCS);
       TCALLINGCONV(AAPCS_VFP);
       TCALLINGCONV(IntelOclBicc);
       TCALLINGCONV(Swift);
       TCALLINGCONV(PreserveMost);
       TCALLINGCONV(PreserveAll);
     case CC_SpirFunction: return CXCallingConv_Unexposed;