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//===- llvm/Analysis/WithCache.h - KnownBits cache for pointers -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Store a pointer to any type along with the KnownBits information for it
// that is computed lazily (if required).
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_WITHCACHE_H
#define LLVM_ANALYSIS_WITHCACHE_H
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/KnownBits.h"
#include <type_traits>
namespace llvm {
struct SimplifyQuery;
KnownBits computeKnownBits(const Value *V, unsigned Depth,
const SimplifyQuery &Q);
template <typename Arg> class WithCache {
static_assert(std::is_pointer_v<Arg>, "WithCache requires a pointer type!");
using UnderlyingType = std::remove_pointer_t<Arg>;
constexpr static bool IsConst = std::is_const_v<Arg>;
template <typename T, bool Const>
using conditionally_const_t = std::conditional_t<Const, const T, T>;
using PointerType = conditionally_const_t<UnderlyingType *, IsConst>;
using ReferenceType = conditionally_const_t<UnderlyingType &, IsConst>;
// Store the presence of the KnownBits information in one of the bits of
// Pointer.
// true -> present
// false -> absent
mutable PointerIntPair<PointerType, 1, bool> Pointer;
mutable KnownBits Known;
void calculateKnownBits(const SimplifyQuery &Q) const {
Known = computeKnownBits(Pointer.getPointer(), 0, Q);
Pointer.setInt(true);
}
public:
WithCache(PointerType Pointer) : Pointer(Pointer, false) {}
WithCache(PointerType Pointer, const KnownBits &Known)
: Pointer(Pointer, true), Known(Known) {}
[[nodiscard]] PointerType getValue() const { return Pointer.getPointer(); }
[[nodiscard]] const KnownBits &getKnownBits(const SimplifyQuery &Q) const {
if (!hasKnownBits())
calculateKnownBits(Q);
return Known;
}
[[nodiscard]] bool hasKnownBits() const { return Pointer.getInt(); }
operator PointerType() const { return Pointer.getPointer(); }
PointerType operator->() const { return Pointer.getPointer(); }
ReferenceType operator*() const { return *Pointer.getPointer(); }
};
} // namespace llvm
#endif
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