[mips] Handle transparent unions correctly.

Summary:
This fixes MultiSource/Applications/lemon on big-endian N32 by correcting the
handling of the argument to wait(). glibc defines it as a transparent union of
void* and int*. Such unions are passed according to the rules of the first
member so the argument must be passed as if it were a void* (sign extended from
i32 to i64) and not as a union (shifted to the upper bits of an i64).

wait() already behaves correctly on big-endian O32 and N64 since the union is
already the same size as an argument slot.

Reviewers: atanasyan

Reviewed By: atanasyan

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D6963

llvm-svn: 225981

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index aafe05aab6c..6ad34951576 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -5693,6 +5693,8 @@ llvm::Type *MipsABIInfo::getPaddingType(uint64_t OrigOffset,
 
 ABIArgInfo
 MipsABIInfo::classifyArgumentType(QualType Ty, uint64_t &Offset) const {
+  Ty = useFirstFieldIfTransparentUnion(Ty);
+
   uint64_t OrigOffset = Offset;
   uint64_t TySize = getContext().getTypeSize(Ty);
   uint64_t Align = getContext().getTypeAlign(Ty) / 8;