//===- llvm/CodeGen/VirtRegMap.h - Virtual Register Map ---------*- 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 implements a virtual register map. This maps virtual registers to

// physical registers and virtual registers to stack slots. It is created and

// updated by a register allocator and then used by a machine code rewriter that

// adds spill code and rewrites virtual into physical register references.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_VIRTREGMAP_H

#define LLVM_CODEGEN_VIRTREGMAP_H

#include "llvm/ADT/IndexedMap.h"

#include "llvm/CodeGen/MachineFunctionPass.h"

#include "llvm/CodeGen/TargetRegisterInfo.h"

#include "llvm/MC/MCRegisterInfo.h"

#include "llvm/Pass.h"

#include <cassert>

namespace llvm {

class MachineFunction;

class MachineRegisterInfo;

class raw_ostream;

class TargetInstrInfo;

  class VirtRegMap : public MachineFunctionPass {

  public:

    enum {

      NO_PHYS_REG = 0,

      NO_STACK_SLOT = (1L << 30)-1,

      MAX_STACK_SLOT = (1L << 18)-1

    };

  private:

    MachineRegisterInfo *MRI;

    const TargetInstrInfo *TII;

    const TargetRegisterInfo *TRI;

    MachineFunction *MF;

    /// Virt2PhysMap - This is a virtual to physical register

    /// mapping. Each virtual register is required to have an entry in

    /// it; even spilled virtual registers (the register mapped to a

    /// spilled register is the temporary used to load it from the

    /// stack).

    IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2PhysMap;

    /// Virt2StackSlotMap - This is virtual register to stack slot

    /// mapping. Each spilled virtual register has an entry in it

    /// which corresponds to the stack slot this register is spilled

    /// at.

    IndexedMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap;

    /// Virt2SplitMap - This is virtual register to splitted virtual register

    /// mapping.

    IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2SplitMap;

    /// createSpillSlot - Allocate a spill slot for RC from MFI.

    unsigned createSpillSlot(const TargetRegisterClass *RC);

  public:

    static char ID;

    VirtRegMap() : MachineFunctionPass(ID), Virt2PhysMap(NO_PHYS_REG),

                   Virt2StackSlotMap(NO_STACK_SLOT), Virt2SplitMap(0) {}

    VirtRegMap(const VirtRegMap &) = delete;

    VirtRegMap &operator=(const VirtRegMap &) = delete;

    bool runOnMachineFunction(MachineFunction &MF) override;

    void getAnalysisUsage(AnalysisUsage &AU) const override {

      AU.setPreservesAll();

      MachineFunctionPass::getAnalysisUsage(AU);

    }

    MachineFunction &getMachineFunction() const {

      assert(MF && "getMachineFunction called before runOnMachineFunction");

      return *MF;

    }

    MachineRegisterInfo &getRegInfo() const { return *MRI; }

    const TargetRegisterInfo &getTargetRegInfo() const { return *TRI; }

    void grow();

    /// returns true if the specified virtual register is

    /// mapped to a physical register

    bool hasPhys(unsigned virtReg) const {

      return getPhys(virtReg) != NO_PHYS_REG;

    }

    /// returns the physical register mapped to the specified

    /// virtual register

    unsigned getPhys(unsigned virtReg) const {

      assert(TargetRegisterInfo::isVirtualRegister(virtReg));

      return Virt2PhysMap[virtReg];

    }

    /// creates a mapping for the specified virtual register to

    /// the specified physical register

    void assignVirt2Phys(unsigned virtReg, MCPhysReg physReg);

    /// clears the specified virtual register's, physical

    /// register mapping

    void clearVirt(unsigned virtReg) {

      assert(TargetRegisterInfo::isVirtualRegister(virtReg));

      assert(Virt2PhysMap[virtReg] != NO_PHYS_REG &&

             "attempt to clear a not assigned virtual register");

      Virt2PhysMap[virtReg] = NO_PHYS_REG;

    }

    /// clears all virtual to physical register mappings

    void clearAllVirt() {

      Virt2PhysMap.clear();

      grow();

    }

    /// returns true if VirtReg is assigned to its preferred physreg.

    bool hasPreferredPhys(unsigned VirtReg);

    /// returns true if VirtReg has a known preferred register.

    /// This returns false if VirtReg has a preference that is a virtual

    /// register that hasn't been assigned yet.

    bool hasKnownPreference(unsigned VirtReg);

    /// records virtReg is a split live interval from SReg.

    void setIsSplitFromReg(unsigned virtReg, unsigned SReg) {

      Virt2SplitMap[virtReg] = SReg;

    }

    /// returns the live interval virtReg is split from.

    unsigned getPreSplitReg(unsigned virtReg) const {

      return Virt2SplitMap[virtReg];

    }

    /// getOriginal - Return the original virtual register that VirtReg descends

    /// from through splitting.

    /// A register that was not created by splitting is its own original.

    /// This operation is idempotent.

    unsigned getOriginal(unsigned VirtReg) const {

      unsigned Orig = getPreSplitReg(VirtReg);

      return Orig ? 
Orig2.81M
 : 
VirtReg7.11M
;

    }

    /// returns true if the specified virtual register is not

    /// mapped to a stack slot or rematerialized.

    bool isAssignedReg(unsigned virtReg) const {

      if (getStackSlot(virtReg) == NO_STACK_SLOT)

        return true;

      // Split register can be assigned a physical register as well as a

      // stack slot or remat id.

      return (Virt2SplitMap[virtReg] && 
Virt2PhysMap[virtReg] != NO_PHYS_REG10
);

    }

    /// returns the stack slot mapped to the specified virtual

    /// register

    int getStackSlot(unsigned virtReg) const {

      assert(TargetRegisterInfo::isVirtualRegister(virtReg));

      return Virt2StackSlotMap[virtReg];

    }

    /// create a mapping for the specifed virtual register to

    /// the next available stack slot

    int assignVirt2StackSlot(unsigned virtReg);

    /// create a mapping for the specified virtual register to

    /// the specified stack slot

    void assignVirt2StackSlot(unsigned virtReg, int SS);

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

    void dump() const;

  };

  inline raw_ostream &operator<<(raw_ostream &OS, const VirtRegMap &VRM) {

    VRM.print(OS);

    return OS;

  }

} // end llvm namespace

#endif // LLVM_CODEGEN_VIRTREGMAP_H