[hip] Allow the declaration of functions with variadic arguments in HIP.

Summary:
- As variadic parameters have the lowest rank in overload resolution,
  without real usage of `va_arg`, they are commonly used as the
  catch-all fallbacks in SFINAE. As the front-end still reports errors
  on calls to `va_arg`, the declaration of functions with variadic
  arguments should be allowed in general.

Reviewers: jlebar, tra, yaxunl

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69389

1 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index c2c7b8bf653..e33d69c86b3 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -7694,6 +7694,8 @@ public:
   ABIArgInfo classifyArgumentType(QualType Ty, unsigned &NumRegsLeft) const;
 
   void computeInfo(CGFunctionInfo &FI) const override;
+  Address EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
+                    QualType Ty) const override;
 };
 
 bool AMDGPUABIInfo::isHomogeneousAggregateBaseType(QualType Ty) const {
@@ -7757,6 +7759,11 @@ void AMDGPUABIInfo::computeInfo(CGFunctionInfo &FI) const {
   }
 }
 
+Address AMDGPUABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
+                                 QualType Ty) const {
+  llvm_unreachable("AMDGPU does not support varargs");
+}
+
 ABIArgInfo AMDGPUABIInfo::classifyReturnType(QualType RetTy) const {
   if (isAggregateTypeForABI(RetTy)) {
     // Records with non-trivial destructors/copy-constructors should not be