[mips] Fix va_arg() for pointer types on big-endian N32.

Summary:
The Mips ABI's treat pointers in the same way as integers. They are
sign-extended to 32-bit for O32, and 64-bit for N32/N64. This doesn't matter
for O32 and N64 where pointers are already the correct width but it does matter
for big-endian N32, where pointers are 32-bit and need promoting.

The caller side is already passing pointers correctly. This patch corrects the
callee.

Reviewers: vmedic, atanasyan

Reviewed By: atanasyan

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D6812

llvm-svn: 225782

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 0fef4462eb93..7c0ce7a7cc33 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -3315,8 +3315,12 @@ Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
   llvm::Value *Val = Builder.CreateLoad(ArgPtr);
 
   // If EmitVAArg promoted the type, we must truncate it.
-  if (ArgTy != Val->getType())
-    Val = Builder.CreateTrunc(Val, ArgTy);
+  if (ArgTy != Val->getType()) {
+    if (ArgTy->isPointerTy() && !Val->getType()->isPointerTy())
+      Val = Builder.CreateIntToPtr(Val, ArgTy);
+    else
+      Val = Builder.CreateTrunc(Val, ArgTy);
+  }
 
   return Val;
 }