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//===------------ MIRVRegNamerUtils.h - MIR VReg Renaming Utilities -------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// The purpose of these utilities is to abstract out parts of the MIRCanon pass
// that are responsible for renaming virtual registers with the purpose of
// sharing code with a MIRVRegNamer pass that could be the analog of the
// opt -instnamer pass.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_MIRVREGNAMERUTILS_H
#define LLVM_LIB_CODEGEN_MIRVREGNAMERUTILS_H
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
/// VRegRenamer - This class is used for renaming vregs in a machine basic
/// block according to semantics of the instruction.
class VRegRenamer {
class NamedVReg {
Register Reg;
std::string Name;
public:
NamedVReg(Register Reg, std::string Name = "") : Reg(Reg), Name(Name) {}
NamedVReg(std::string Name = "") : Reg(~0U), Name(Name) {}
const std::string &getName() const { return Name; }
Register getReg() const { return Reg; }
};
MachineRegisterInfo &MRI;
unsigned CurrentBBNumber = 0;
/// Given an Instruction, construct a hash of the operands
/// of the instructions along with the opcode.
/// When dealing with virtual registers, just hash the opcode of
/// the instruction defining that vreg.
/// Handle immediates, registers (physical and virtual) explicitly,
/// and return a common value for the other cases.
/// Instruction will be named in the following scheme
/// bb<block_no>_hash_<collission_count>.
std::string getInstructionOpcodeHash(MachineInstr &MI);
/// For all the VRegs that are candidates for renaming,
/// return a mapping from old vregs to new vregs with names.
std::map<unsigned, unsigned>
getVRegRenameMap(const std::vector<NamedVReg> &VRegs);
/// Perform replacing of registers based on the <old,new> vreg map.
bool doVRegRenaming(const std::map<unsigned, unsigned> &VRegRenameMap);
/// createVirtualRegister - Given an existing vreg, create a named vreg to
/// take its place. The name is determined by calling
/// getInstructionOpcodeHash.
unsigned createVirtualRegister(unsigned VReg);
/// Create a vreg with name and return it.
unsigned createVirtualRegisterWithLowerName(unsigned VReg, StringRef Name);
/// Linearly traverse the MachineBasicBlock and rename each instruction's
/// vreg definition based on the semantics of the instruction.
/// Names are as follows bb<BBNum>_hash_[0-9]+
bool renameInstsInMBB(MachineBasicBlock *MBB);
public:
VRegRenamer() = delete;
VRegRenamer(MachineRegisterInfo &MRI) : MRI(MRI) {}
/// Same as the above, but sets a BBNum depending on BB traversal that
/// will be used as prefix for the vreg names.
bool renameVRegs(MachineBasicBlock *MBB, unsigned BBNum) {
CurrentBBNumber = BBNum;
return renameInstsInMBB(MBB);
}
};
} // namespace llvm
#endif
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