diff options
Diffstat (limited to 'llvm/lib/IR/ConstantFold.cpp')
| -rw-r--r-- | llvm/lib/IR/ConstantFold.cpp | 24 |
1 files changed, 3 insertions, 21 deletions
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp index c9ee60d684f9..66e3a75833e2 100644 --- a/llvm/lib/IR/ConstantFold.cpp +++ b/llvm/lib/IR/ConstantFold.cpp @@ -1979,32 +1979,14 @@ static Constant *foldGEPOfGEP(GEPOperator *GEP, Type *PointeeTy, bool InBounds, I != E; ++I) LastI = I; - // 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. + // We can't combine GEPs if the last index is a struct type. if (!LastI.isSequential()) return nullptr; + // We could perform the transform with non-constant index, but prefer leaving + // it as GEP of GEP rather than GEP of add for now. ConstantInt *CI = dyn_cast<ConstantInt>(Idx0); if (!CI) return nullptr; - if (LastI.isBoundedSequential() && - !isIndexInRangeOfArrayType(LastI.getSequentialNumElements(), CI)) - return nullptr; // TODO: This code may be extended to handle vectors as well. auto *LastIdx = cast<Constant>(GEP->getOperand(GEP->getNumOperands()-1)); |