+ // We cannot combine indices if doing so would take us outside of an
+ // array or vector. Doing otherwise could trick us if we evaluated such a
+ // GEP as part of a load.
+ //
+ // e.g. Consider if the original GEP was:
+ // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c,
+ // i32 0, i32 0, i64 0)
+ //
+ // If we then tried to offset it by '8' to get to the third element,
+ // an i8, we should *not* get:
+ // i8* getelementptr ({ [2 x i8], i32, i8, [3 x i8] }* @main.c,
+ // i32 0, i32 0, i64 8)
+ //
+ // This GEP tries to index array element '8 which runs out-of-bounds.
+ // Subsequent evaluation would get confused and produce erroneous results.
+ //
+ // The following prohibits such a GEP from being formed by checking to see
+ // if the index is in-range with respect to an array or vector.
+ bool PerformFold = false;
+ if (Idx0->isNullValue())
+ PerformFold = true;
+ else if (SequentialType *STy = dyn_cast_or_null<SequentialType>(LastTy))
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx0))
+ PerformFold = isIndexInRangeOfSequentialType(STy, CI);
+
+ if (PerformFold) {