Cherry-pick Clang upstream r199830 - Handle va_arg on struct types for the le32 target (PNaCl and E…

lib/CodeGen/CGExprAgg.cpp

 //===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This contains code to emit Aggregate Expr nodes as LLVM code.
@@ skipping 910 matching lines @@
 
 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
   Visit(CE->getChosenSubExpr());
 }
 
 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
   llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
   llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
 
   if (!ArgPtr) {
-    CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
+    // If EmitVAArg fails, we fall back to the LLVM instruction.
+    llvm::Value *Val =
+        Builder.CreateVAArg(ArgValue, CGF.ConvertType(VE->getType()));
+    if (!Dest.isIgnored())
+      Builder.CreateStore(Val, Dest.getAddr());
     return;
   }
 
   EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType()));
 }
 
 void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
   // Ensure that we have a slot, but if we already do, remember
   // whether it was externally destructed.
   bool wasExternallyDestructed = Dest.isExternallyDestructed();
@@ skipping 524 matching lines @@
   // memcpy, as well as the TBAA tags for the members of the struct, in case
   // the optimizer wishes to expand it in to scalar memory operations.
   llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty);
   
   Builder.CreateMemCpy(DestPtr, SrcPtr,
                        llvm::ConstantInt::get(IntPtrTy, 
                                               TypeInfo.first.getQuantity()),
                        alignment.getQuantity(), isVolatile,
                        /*TBAATag=*/0, TBAAStructTag);
 }