Fix PR14034, an infloop / heap corruption / crash bug in the new SROA.
Thanks to Benjamin for the raw test case. This one took about 50 times
longer to reduce than to fix. =/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165476 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index b279389..ca76251 100644
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -1786,6 +1786,8 @@
       ElementTy = SeqTy->getElementType();
       Indices.push_back(IRB.getInt(APInt(TD.getPointerSizeInBits(), 0)));
     } else if (StructType *STy = dyn_cast<StructType>(ElementTy)) {
+      if (STy->element_begin() == STy->element_end())
+        break; // Nothing left to descend into.
       ElementTy = *STy->element_begin();
       Indices.push_back(IRB.getInt32(0));
     } else {