RegisterUsageInfo.h

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//==- RegisterUsageInfo.h - Register Usage Informartion Storage --*- 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
//
//===----------------------------------------------------------------------===//
/// \file
/// This pass is required to take advantage of the interprocedural register
/// allocation infrastructure.
///
/// This pass is simple immutable pass which keeps RegMasks (calculated based on
/// actual register allocation) for functions in a module and provides simple
/// API to query this information.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_PHYSICALREGISTERUSAGEINFO_H
#define LLVM_CODEGEN_PHYSICALREGISTERUSAGEINFO_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/IR/Instructions.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include <cstdint>
#include <vector>

namespace llvm {

class Function;
class LLVMTargetMachine;

class PhysicalRegisterUsageInfo : public ImmutablePass {
public:
  static char ID;

  PhysicalRegisterUsageInfo() : ImmutablePass(ID) {
    PassRegistry &Registry = *PassRegistry::getPassRegistry();
    initializePhysicalRegisterUsageInfoPass(Registry);
  }

  /// Set TargetMachine which is used to print analysis.
  void setTargetMachine(const LLVMTargetMachine &TM);

  bool doInitialization(Module &M) override;

  bool doFinalization(Module &M) override;

  /// To store RegMask for given Function *.
  void storeUpdateRegUsageInfo(const Function &FP,
                               ArrayRef<uint32_t> RegMask);

  /// To query stored RegMask for given Function *, it will returns ane empty
  /// array if function is not known.
  ArrayRef<uint32_t> getRegUsageInfo(const Function &FP);

  void print(raw_ostream &OS, const Module *M = nullptr) const override;

private:
  /// A Dense map from Function * to RegMask.
  /// In RegMask 0 means register used (clobbered) by function.
  /// and 1 means content of register will be preserved around function call.
  DenseMap<const Function *, std::vector<uint32_t>> RegMasks;

  const LLVMTargetMachine *TM;
};

} // end namespace llvm

#endif // LLVM_CODEGEN_PHYSICALREGISTERUSAGEINFO_H