Teach ARM va_arg to ignore empty structs.

Empty structs are ignored for parameter passing purposes, but va_arg was
incrementing the pointer anyway which could lead to va_list getting out of
sync.

llvm-svn: 184605

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index c9f0d757946..bef0d058d6f 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -3593,6 +3593,12 @@ llvm::Value *ARMABIInfo::EmitVAArg(llvm::Value *VAListAddr, QualType Ty,
   llvm::Value *VAListAddrAsBPP = Builder.CreateBitCast(VAListAddr, BPP, "ap");
   llvm::Value *Addr = Builder.CreateLoad(VAListAddrAsBPP, "ap.cur");
 
+  if (isEmptyRecord(getContext(), Ty, true)) {
+    // These are ignored for parameter passing purposes.
+    llvm::Type *PTy = llvm::PointerType::getUnqual(CGF.ConvertType(Ty));
+    return Builder.CreateBitCast(Addr, PTy);
+  }
+
   uint64_t Size = CGF.getContext().getTypeSize(Ty) / 8;
   uint64_t TyAlign = CGF.getContext().getTypeAlign(Ty) / 8;
   bool IsIndirect = false;