Don't try to create a GEP when the pointee type is unsized (such GEPs

are invalid).  Fixes a crash on array1.C from the GCC testsuite when
compiled with dragonegg.

llvm-svn: 147946

2 files changed, 14 insertions, 1 deletions

diff --git a/llvm/lib/VMCore/ConstantFold.cpp b/llvm/lib/VMCore/ConstantFold.cpp
index 4d7a857de5c..62ef25b6430 100644
--- a/llvm/lib/VMCore/ConstantFold.cpp
+++ b/llvm/lib/VMCore/ConstantFold.cpp
@@ -104,7 +104,8 @@ static Constant *FoldBitCast(Constant *V, Type *DestTy) {
   // the first element.  If so, return the appropriate GEP instruction.
   if (PointerType *PTy = dyn_cast<PointerType>(V->getType()))
     if (PointerType *DPTy = dyn_cast<PointerType>(DestTy))
-      if (PTy->getAddressSpace() == DPTy->getAddressSpace()) {
+      if (PTy->getAddressSpace() == DPTy->getAddressSpace()
+          && DPTy->getElementType()->isSized()) {
         SmallVector<Value*, 8> IdxList;
         Value *Zero =
           Constant::getNullValue(Type::getInt32Ty(DPTy->getContext()));
diff --git a/llvm/test/Transforms/InstCombine/2012-01-11-OpaqueBitcastCrash.ll b/llvm/test/Transforms/InstCombine/2012-01-11-OpaqueBitcastCrash.ll
new file mode 100644
index 00000000000..abab9dc5702
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/2012-01-11-OpaqueBitcastCrash.ll
@@ -0,0 +1,12 @@
+; RUN: opt < %s -instcombine -disable-output
+
+%opaque_struct = type opaque
+
+@G = external global [0 x %opaque_struct]
+
+declare void @foo(%opaque_struct*)
+
+define void @bar() {
+  call void @foo(%opaque_struct* bitcast ([0 x %opaque_struct]* @G to %opaque_struct*))
+  ret void
+}