llvm/llvm/include/llvm/Transforms/Utils/FunctionComparator.h

//===- FunctionComparator.h - Function Comparator ---------------*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines the FunctionComparator and GlobalNumberState classes which
// are used by the MergeFunctions pass for comparing functions.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TRANSFORMS_UTILS_FUNCTIONCOMPARATOR_H
#define LLVM_TRANSFORMS_UTILS_FUNCTIONCOMPARATOR_H

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/ValueMap.h"
#include "llvm/Support/AtomicOrdering.h"
#include "llvm/Support/Casting.h"
#include <cstdint>
#include <tuple>

namespace llvm {

class APFloat;
class AttributeList;
class APInt;
class BasicBlock;
class Constant;
class Function;
class GlobalValue;
class InlineAsm;
class Instruction;
class MDNode;
class Type;
class Value;

/// GlobalNumberState assigns an integer to each global value in the program,
/// which is used by the comparison routine to order references to globals. This
/// state must be preserved throughout the pass, because Functions and other
/// globals need to maintain their relative order. Globals are assigned a number
/// when they are first visited. This order is deterministic, and so the
/// assigned numbers are as well. When two functions are merged, neither number
/// is updated. If the symbols are weak, this would be incorrect. If they are
/// strong, then one will be replaced at all references to the other, and so
/// direct callsites will now see one or the other symbol, and no update is
/// necessary. Note that if we were guaranteed unique names, we could just
/// compare those, but this would not work for stripped bitcodes or for those
/// few symbols without a name.
class GlobalNumberState { … };

/// FunctionComparator - Compares two functions to determine whether or not
/// they will generate machine code with the same behaviour. DataLayout is
/// used if available. The comparator always fails conservatively (erring on the
/// side of claiming that two functions are different).
class FunctionComparator { … };

} // end namespace llvm

#endif // LLVM_TRANSFORMS_UTILS_FUNCTIONCOMPARATOR_H