163 lines · cpp
1//===- LiveRegUnits.cpp - Register Unit Set -------------------------------===//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/// \file This file imlements the LiveRegUnits set.10//11//===----------------------------------------------------------------------===//12 13#include "llvm/CodeGen/LiveRegUnits.h"14#include "llvm/CodeGen/MachineBasicBlock.h"15#include "llvm/CodeGen/MachineFrameInfo.h"16#include "llvm/CodeGen/MachineFunction.h"17#include "llvm/CodeGen/MachineOperand.h"18#include "llvm/CodeGen/MachineRegisterInfo.h"19 20using namespace llvm;21 22void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) {23 for (MCRegUnit U : TRI->regunits()) {24 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {25 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) {26 Units.reset(static_cast<unsigned>(U));27 break;28 }29 }30 }31}32 33void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) {34 for (MCRegUnit U : TRI->regunits()) {35 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {36 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) {37 Units.set(static_cast<unsigned>(U));38 break;39 }40 }41 }42}43 44void LiveRegUnits::stepBackward(const MachineInstr &MI) {45 // Remove defined registers and regmask kills from the set.46 for (const MachineOperand &MOP : MI.operands()) {47 if (MOP.isReg()) {48 if (MOP.isDef() && MOP.getReg().isPhysical())49 removeReg(MOP.getReg());50 continue;51 }52 53 if (MOP.isRegMask()) {54 removeRegsNotPreserved(MOP.getRegMask());55 continue;56 }57 }58 59 // Add uses to the set.60 for (const MachineOperand &MOP : MI.operands()) {61 if (!MOP.isReg() || !MOP.readsReg())62 continue;63 64 if (MOP.getReg().isPhysical())65 addReg(MOP.getReg());66 }67}68 69void LiveRegUnits::accumulate(const MachineInstr &MI) {70 // Add defs, uses and regmask clobbers to the set.71 for (const MachineOperand &MOP : MI.operands()) {72 if (MOP.isReg()) {73 if (!MOP.getReg().isPhysical())74 continue;75 if (MOP.isDef() || MOP.readsReg())76 addReg(MOP.getReg());77 continue;78 }79 80 if (MOP.isRegMask()) {81 addRegsInMask(MOP.getRegMask());82 continue;83 }84 }85}86 87/// Add live-in registers of basic block \p MBB to \p LiveUnits.88static void addBlockLiveIns(LiveRegUnits &LiveUnits,89 const MachineBasicBlock &MBB) {90 for (const auto &LI : MBB.liveins())91 LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask);92}93 94/// Add live-out registers of basic block \p MBB to \p LiveUnits.95static void addBlockLiveOuts(LiveRegUnits &LiveUnits,96 const MachineBasicBlock &MBB) {97 for (const auto &LO : MBB.liveouts())98 LiveUnits.addRegMasked(LO.PhysReg, LO.LaneMask);99}100 101/// Adds all callee saved registers to \p LiveUnits.102static void addCalleeSavedRegs(LiveRegUnits &LiveUnits,103 const MachineFunction &MF) {104 const MachineRegisterInfo &MRI = MF.getRegInfo();105 const MachineFrameInfo &MFI = MF.getFrameInfo();106 for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR) {107 const unsigned N = *CSR;108 109 const auto &CSI = MFI.getCalleeSavedInfo();110 auto Info =111 llvm::find_if(CSI, [N](auto Info) { return Info.getReg() == N; });112 // If we have no info for this callee-saved register, assume it is liveout113 if (Info == CSI.end() || Info->isRestored())114 LiveUnits.addReg(N);115 }116}117 118void LiveRegUnits::addPristines(const MachineFunction &MF) {119 const MachineFrameInfo &MFI = MF.getFrameInfo();120 if (!MFI.isCalleeSavedInfoValid())121 return;122 /// This function will usually be called on an empty object, handle this123 /// as a special case.124 if (empty()) {125 /// Add all callee saved regs, then remove the ones that are saved and126 /// restored.127 addCalleeSavedRegs(*this, MF);128 /// Remove the ones that are not saved/restored; they are pristine.129 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())130 removeReg(Info.getReg());131 return;132 }133 /// If a callee-saved register that is not pristine is already present134 /// in the set, we should make sure that it stays in it. Precompute the135 /// set of pristine registers in a separate object.136 /// Add all callee saved regs, then remove the ones that are saved+restored.137 LiveRegUnits Pristine(*TRI);138 addCalleeSavedRegs(Pristine, MF);139 /// Remove the ones that are not saved/restored; they are pristine.140 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())141 Pristine.removeReg(Info.getReg());142 addUnits(Pristine.getBitVector());143}144 145void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) {146 const MachineFunction &MF = *MBB.getParent();147 addPristines(MF);148 addBlockLiveOuts(*this, MBB);149 150 // For the return block: Add all callee saved registers.151 if (MBB.isReturnBlock()) {152 const MachineFrameInfo &MFI = MF.getFrameInfo();153 if (MFI.isCalleeSavedInfoValid())154 addCalleeSavedRegs(*this, MF);155 }156}157 158void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) {159 const MachineFunction &MF = *MBB.getParent();160 addPristines(MF);161 addBlockLiveIns(*this, MBB);162}163