diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp index 5a8e41c74ea..e42de2a7e39 100644 --- a/lib/VMCore/ConstantFold.cpp +++ b/lib/VMCore/ConstantFold.cpp @@ -971,6 +971,18 @@ Constant *llvm::ConstantFoldGetElementPtr(const Constant *C, assert(Ty != 0 && "Invalid indices for GEP!"); return ConstantPointerNull::get(PointerType::get(Ty)); } + + if (IdxList.size() == 1) { + const Type *ElTy = cast(C->getType())->getElementType(); + if (unsigned ElSize = ElTy->getPrimitiveSize()) { + // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm + // type, we can statically fold this. + Constant *R = ConstantUInt::get(Type::UIntTy, ElSize); + R = ConstantExpr::getCast(R, IdxList[0]->getType()); + R = ConstantExpr::getMul(R, IdxList[0]); + return ConstantExpr::getCast(R, C->getType()); + } + } } if (ConstantExpr *CE = dyn_cast(const_cast(C))) {