[clang] [X86_64] Fix empty field error in vaarg of C++. (PR #90389)

[Eli Friedman via cfe-commits]

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@@ -3122,9 +3122,25 @@ Address X86_64ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
     CGF.Builder.CreateStore(V, CGF.Builder.CreateStructGEP(Tmp, 1));
 
     RegAddr = Tmp.withElementType(LTy);
-  } else if (neededInt) {
-    RegAddr = Address(CGF.Builder.CreateGEP(CGF.Int8Ty, RegSaveArea, gp_offset),
-                      LTy, CharUnits::fromQuantity(8));
+  } else if (neededInt || neededSSE == 1) {
+    llvm::Value *Offset = neededInt ? gp_offset : fp_offset;
+    uint64_t Alignment = neededInt ? 8 : 16;
+    Address Tmp = Address::invalid();
+    if (AI.isDirect() && AI.getDirectOffset() == 8) {
+      Tmp = CGF.CreateMemTemp(Ty);
+      llvm::StructType *ST = cast<llvm::StructType>(LTy);
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efriedma-quic wrote:

ST is also wrong... please write a few more testcases.

https://github.com/llvm/llvm-project/pull/90389