fix PR6332, allowing an index of zero into a zero sized array 
even if the element of the array has no size.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101662 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/TargetData.cpp b/lib/Target/TargetData.cpp
index abee2e1..d89fafd 100644
--- a/lib/Target/TargetData.cpp
+++ b/lib/Target/TargetData.cpp
@@ -630,8 +630,8 @@
       Ty = cast<SequentialType>(Ty)->getElementType();
 
       // Get the array index and the size of each array element.
-      int64_t arrayIdx = cast<ConstantInt>(Indices[CurIDX])->getSExtValue();
-      Result += arrayIdx * (int64_t)getTypeAllocSize(Ty);
+      if (int64_t arrayIdx = cast<ConstantInt>(Indices[CurIDX])->getSExtValue())
+        Result += arrayIdx * (int64_t)getTypeAllocSize(Ty);
     }
   }