Do GEP offset calculations with unsigned math rather than signed math

to avoid undefined behavior on overflow, noticed by John Regehr.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109594 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/TargetData.cpp b/lib/Target/TargetData.cpp
index 9b207c1f28cf2645eb2c2492178fc7fc0d5be40f..65f514c26474e8e021f122b7465dab6f9d5ba9da 100644 (file)
--- a/lib/Target/TargetData.cpp
+++ b/lib/Target/TargetData.cpp
@@ -625,7 +625,7 @@ uint64_t TargetData::getIndexedOffset(const Type *ptrTy, Value* const* Indices,
 
       // Get the array index and the size of each array element.
       if (int64_t arrayIdx = cast<ConstantInt>(Indices[CurIDX])->getSExtValue())
-        Result += arrayIdx * (int64_t)getTypeAllocSize(Ty);
+        Result += (uint64_t)arrayIdx * getTypeAllocSize(Ty);
     }
   }