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//===- GetElementPtrTypeIterator.h ------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements an iterator for walking through the types indexed by
// getelementptr instructions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_GETELEMENTPTRTYPEITERATOR_H
#define LLVM_IR_GETELEMENTPTRTYPEITERATOR_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/User.h"
#include "llvm/Support/Casting.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <iterator>
namespace llvm {
template<typename ItTy = User::const_op_iterator>
class generic_gep_type_iterator
: public std::iterator<std::forward_iterator_tag, Type *, ptrdiff_t> {
using super = std::iterator<std::forward_iterator_tag, Type *, ptrdiff_t>;
ItTy OpIt;
PointerUnion<StructType *, Type *> CurTy;
enum : uint64_t { Unbounded = -1ull };
uint64_t NumElements = Unbounded;
generic_gep_type_iterator() = default;
public:
static generic_gep_type_iterator begin(Type *Ty, ItTy It) {
generic_gep_type_iterator I;
I.CurTy = Ty;
I.OpIt = It;
return I;
}
static generic_gep_type_iterator end(ItTy It) {
generic_gep_type_iterator I;
I.OpIt = It;
return I;
}
bool operator==(const generic_gep_type_iterator& x) const {
return OpIt == x.OpIt;
}
bool operator!=(const generic_gep_type_iterator& x) const {
return !operator==(x);
}
// FIXME: Make this the iterator's operator*() after the 4.0 release.
// operator*() had a different meaning in earlier releases, so we're
// temporarily not giving this iterator an operator*() to avoid a subtle
// semantics break.
Type *getIndexedType() const {
if (auto *T = CurTy.dyn_cast<Type *>())
return T;
return CurTy.get<StructType *>()->getTypeAtIndex(getOperand());
}
Value *getOperand() const { return const_cast<Value *>(&**OpIt); }
generic_gep_type_iterator& operator++() { // Preincrement
Type *Ty = getIndexedType();
if (auto *STy = dyn_cast<SequentialType>(Ty)) {
CurTy = STy->getElementType();
NumElements = STy->getNumElements();
} else
CurTy = dyn_cast<StructType>(Ty);
++OpIt;
return *this;
}
generic_gep_type_iterator operator++(int) { // Postincrement
generic_gep_type_iterator tmp = *this; ++*this; return tmp;
}
// All of the below API is for querying properties of the "outer type", i.e.
// the type that contains the indexed type. Most of the time this is just
// the type that was visited immediately prior to the indexed type, but for
// the first element this is an unbounded array of the GEP's source element
// type, for which there is no clearly corresponding IR type (we've
// historically used a pointer type as the outer type in this case, but
// pointers will soon lose their element type).
//
// FIXME: Most current users of this class are just interested in byte
// offsets (a few need to know whether the outer type is a struct because
// they are trying to replace a constant with a variable, which is only
// legal for arrays, e.g. canReplaceOperandWithVariable in SimplifyCFG.cpp);
// we should provide a more minimal API here that exposes not much more than
// that.
bool isStruct() const { return CurTy.is<StructType *>(); }
bool isSequential() const { return CurTy.is<Type *>(); }
StructType *getStructType() const { return CurTy.get<StructType *>(); }
StructType *getStructTypeOrNull() const {
return CurTy.dyn_cast<StructType *>();
}
bool isBoundedSequential() const {
return isSequential() && NumElements != Unbounded;
}
uint64_t getSequentialNumElements() const {
assert(isBoundedSequential());
return NumElements;
}
};
using gep_type_iterator = generic_gep_type_iterator<>;
inline gep_type_iterator gep_type_begin(const User *GEP) {
auto *GEPOp = cast<GEPOperator>(GEP);
return gep_type_iterator::begin(
GEPOp->getSourceElementType(),
GEP->op_begin() + 1);
}
inline gep_type_iterator gep_type_end(const User *GEP) {
return gep_type_iterator::end(GEP->op_end());
}
inline gep_type_iterator gep_type_begin(const User &GEP) {
auto &GEPOp = cast<GEPOperator>(GEP);
return gep_type_iterator::begin(
GEPOp.getSourceElementType(),
GEP.op_begin() + 1);
}
inline gep_type_iterator gep_type_end(const User &GEP) {
return gep_type_iterator::end(GEP.op_end());
}
template<typename T>
inline generic_gep_type_iterator<const T *>
gep_type_begin(Type *Op0, ArrayRef<T> A) {
return generic_gep_type_iterator<const T *>::begin(Op0, A.begin());
}
template<typename T>
inline generic_gep_type_iterator<const T *>
gep_type_end(Type * /*Op0*/, ArrayRef<T> A) {
return generic_gep_type_iterator<const T *>::end(A.end());
}
} // end namespace llvm
#endif // LLVM_IR_GETELEMENTPTRTYPEITERATOR_H
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