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1//===- RegisterCoalescer.h - Register Coalescing Interface ------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file contains the abstract interface for register coalescers,10// allowing them to interact with and query register allocators.11//12//===----------------------------------------------------------------------===//13 14#ifndef LLVM_LIB_CODEGEN_REGISTERCOALESCER_H15#define LLVM_LIB_CODEGEN_REGISTERCOALESCER_H16 17#include "llvm/CodeGen/MachinePassManager.h"18#include "llvm/CodeGen/Register.h"19 20namespace llvm {21 22class MachineInstr;23class TargetRegisterClass;24class TargetRegisterInfo;25 26/// A helper class for register coalescers. When deciding if27/// two registers can be coalesced, CoalescerPair can determine if a copy28/// instruction would become an identity copy after coalescing.29class CoalescerPair {30 const TargetRegisterInfo &TRI;31 32 /// The register that will be left after coalescing. It can be a33 /// virtual or physical register.34 Register DstReg;35 36 /// The virtual register that will be coalesced into dstReg.37 Register SrcReg;38 39 /// The sub-register index of the old DstReg in the new coalesced register.40 unsigned DstIdx = 0;41 42 /// The sub-register index of the old SrcReg in the new coalesced register.43 unsigned SrcIdx = 0;44 45 /// True when the original copy was a partial subregister copy.46 bool Partial = false;47 48 /// True when both regs are virtual and newRC is constrained.49 bool CrossClass = false;50 51 /// True when DstReg and SrcReg are reversed from the original52 /// copy instruction.53 bool Flipped = false;54 55 /// The register class of the coalesced register, or NULL if DstReg56 /// is a physreg. This register class may be a super-register of both57 /// SrcReg and DstReg.58 const TargetRegisterClass *NewRC = nullptr;59 60public:61 CoalescerPair(const TargetRegisterInfo &tri) : TRI(tri) {}62 63 /// Create a CoalescerPair representing a virtreg-to-physreg copy.64 /// No need to call setRegisters().65 CoalescerPair(Register VirtReg, MCRegister PhysReg,66 const TargetRegisterInfo &tri)67 : TRI(tri), DstReg(PhysReg), SrcReg(VirtReg) {}68 69 /// Set registers to match the copy instruction MI. Return70 /// false if MI is not a coalescable copy instruction.71 bool setRegisters(const MachineInstr *);72 73 /// Swap SrcReg and DstReg. Return false if swapping is impossible74 /// because DstReg is a physical register, or SubIdx is set.75 bool flip();76 77 /// Return true if MI is a copy instruction that will become78 /// an identity copy after coalescing.79 bool isCoalescable(const MachineInstr *) const;80 81 /// Return true if DstReg is a physical register.82 bool isPhys() const { return !NewRC; }83 84 /// Return true if the original copy instruction did not copy85 /// the full register, but was a subreg operation.86 bool isPartial() const { return Partial; }87 88 /// Return true if DstReg is virtual and NewRC is a smaller89 /// register class than DstReg's.90 bool isCrossClass() const { return CrossClass; }91 92 /// Return true when getSrcReg is the register being defined by93 /// the original copy instruction.94 bool isFlipped() const { return Flipped; }95 96 /// Return the register (virtual or physical) that will remain97 /// after coalescing.98 Register getDstReg() const { return DstReg; }99 100 /// Return the virtual register that will be coalesced away.101 Register getSrcReg() const { return SrcReg; }102 103 /// Return the subregister index that DstReg will be coalesced into, or 0.104 unsigned getDstIdx() const { return DstIdx; }105 106 /// Return the subregister index that SrcReg will be coalesced into, or 0.107 unsigned getSrcIdx() const { return SrcIdx; }108 109 /// Return the register class of the coalesced register.110 const TargetRegisterClass *getNewRC() const { return NewRC; }111};112 113} // end namespace llvm114 115#endif // LLVM_LIB_CODEGEN_REGISTERCOALESCER_H116