| //===- 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(); |
| const MachineFrameInfo &MFI = MF.getFrameInfo(); |
| for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR) { |
| const unsigned N = *CSR; |
| |
| const auto &CSI = MFI.getCalleeSavedInfo(); |
| auto Info = |
| llvm::find_if(CSI, [N](auto Info) { return Info.getReg() == N; }); |
| // If we have no info for this callee-saved register, assume it is liveout |
| if (Info == CSI.end() || Info->isRestored()) |
| LiveUnits.addReg(N); |
| } |
| } |
| |
| 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); |
| } |