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

lib/CodeGen/CGExprAgg.cpp

Index: lib/CodeGen/CGExprAgg.cpp
diff --git a/lib/CodeGen/CGExprAgg.cpp b/lib/CodeGen/CGExprAgg.cpp
index 9d0f3a9661a68d3f58c60365e1ee59f2becdc606..ea366ddabcb86dcaa630d2ae44df38eecfd2dfe8 100644
--- a/lib/CodeGen/CGExprAgg.cpp
+++ b/lib/CodeGen/CGExprAgg.cpp
@@ -928,7 +928,11 @@ void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
   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;
   }