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//===- LiveRegUnits.cpp - Register Unit Set -------------------------------===//
//
// 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 file imlements the LiveRegUnits set.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LiveRegUnits.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) {
for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
Units.reset(U);
}
}
}
void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) {
for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
Units.set(U);
}
}
}
void LiveRegUnits::stepBackward(const MachineInstr &MI) {
// Remove defined registers and regmask kills from the set.
for (const MachineOperand &MOP : phys_regs_and_masks(MI)) {
if (MOP.isRegMask()) {
removeRegsNotPreserved(MOP.getRegMask());
continue;
}
if (MOP.isDef())
removeReg(MOP.getReg());
}
// Add uses to the set.
for (const MachineOperand &MOP : phys_regs_and_masks(MI)) {
if (!MOP.isReg() || !MOP.readsReg())
continue;
addReg(MOP.getReg());
}
}
void LiveRegUnits::accumulate(const MachineInstr &MI) {
// Add defs, uses and regmask clobbers to the set.
for (const MachineOperand &MOP : phys_regs_and_masks(MI)) {
if (MOP.isRegMask()) {
addRegsInMask(MOP.getRegMask());
continue;
}
if (!MOP.isDef() && !MOP.readsReg())
continue;
addReg(MOP.getReg());
}
}
/// Add live-in registers of basic block \p MBB to \p LiveUnits.
static void addBlockLiveIns(LiveRegUnits &LiveUnits,
const MachineBasicBlock &MBB) {
for (const auto &LI : MBB.liveins())
LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask);
}
/// Adds all callee saved registers to \p LiveUnits.
static void addCalleeSavedRegs(LiveRegUnits &LiveUnits,
const MachineFunction &MF) {
const MachineRegisterInfo &MRI = MF.getRegInfo();
for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR)
LiveUnits.addReg(*CSR);
}
void LiveRegUnits::addPristines(const MachineFunction &MF) {
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (!MFI.isCalleeSavedInfoValid())
return;
/// This function will usually be called on an empty object, handle this
/// as a special case.
if (empty()) {
/// Add all callee saved regs, then remove the ones that are saved and
/// restored.
addCalleeSavedRegs(*this, MF);
/// Remove the ones that are not saved/restored; they are pristine.
for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
removeReg(Info.getReg());
return;
}
/// If a callee-saved register that is not pristine is already present
/// in the set, we should make sure that it stays in it. Precompute the
/// set of pristine registers in a separate object.
/// Add all callee saved regs, then remove the ones that are saved+restored.
LiveRegUnits Pristine(*TRI);
addCalleeSavedRegs(Pristine, MF);
/// Remove the ones that are not saved/restored; they are pristine.
for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
Pristine.removeReg(Info.getReg());
addUnits(Pristine.getBitVector());
}
void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) {
const MachineFunction &MF = *MBB.getParent();
addPristines(MF);
// To get the live-outs we simply merge the live-ins of all successors.
for (const MachineBasicBlock *Succ : MBB.successors())
addBlockLiveIns(*this, *Succ);
// For the return block: Add all callee saved registers.
if (MBB.isReturnBlock()) {
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (MFI.isCalleeSavedInfoValid())
addCalleeSavedRegs(*this, MF);
}
}
void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) {
const MachineFunction &MF = *MBB.getParent();
addPristines(MF);
addBlockLiveIns(*this, MBB);
}
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