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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 /// \file This file imlements the LiveRegUnits set. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/CodeGen/LiveRegUnits.h" 14 15 #include "llvm/CodeGen/MachineBasicBlock.h" 16 #include "llvm/CodeGen/MachineFrameInfo.h" 17 #include "llvm/CodeGen/MachineFunction.h" 18 #include "llvm/CodeGen/MachineInstrBundle.h" 19 #include "llvm/CodeGen/MachineOperand.h" 20 #include "llvm/CodeGen/MachineRegisterInfo.h" 21 #include "llvm/CodeGen/TargetRegisterInfo.h" 22 #include "llvm/MC/MCRegisterInfo.h" 23 24 using namespace llvm; 25 26 void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) { 27 for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) { 28 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) { 29 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) 30 Units.reset(U); 31 } 32 } 33 } 34 35 void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) { 36 for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) { 37 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) { 38 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) 39 Units.set(U); 40 } 41 } 42 } 43 44 void LiveRegUnits::stepBackward(const MachineInstr &MI) { 45 // Remove defined registers and regmask kills from the set. 46 for (const MachineOperand &MOP : phys_regs_and_masks(MI)) { 47 if (MOP.isRegMask()) { 48 removeRegsNotPreserved(MOP.getRegMask()); 49 continue; 50 } 51 52 if (MOP.isDef()) 53 removeReg(MOP.getReg()); 54 } 55 56 // Add uses to the set. 57 for (const MachineOperand &MOP : phys_regs_and_masks(MI)) { 58 if (!MOP.isReg() || !MOP.readsReg()) 59 continue; 60 addReg(MOP.getReg()); 61 } 62 } 63 64 void LiveRegUnits::accumulate(const MachineInstr &MI) { 65 // Add defs, uses and regmask clobbers to the set. 66 for (const MachineOperand &MOP : phys_regs_and_masks(MI)) { 67 if (MOP.isRegMask()) { 68 addRegsInMask(MOP.getRegMask()); 69 continue; 70 } 71 if (!MOP.isDef() && !MOP.readsReg()) 72 continue; 73 addReg(MOP.getReg()); 74 } 75 } 76 77 /// Add live-in registers of basic block \p MBB to \p LiveUnits. 78 static void addBlockLiveIns(LiveRegUnits &LiveUnits, 79 const MachineBasicBlock &MBB) { 80 for (const auto &LI : MBB.liveins()) 81 LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask); 82 } 83 84 /// Adds all callee saved registers to \p LiveUnits. 85 static void addCalleeSavedRegs(LiveRegUnits &LiveUnits, 86 const MachineFunction &MF) { 87 const MachineRegisterInfo &MRI = MF.getRegInfo(); 88 for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR) 89 LiveUnits.addReg(*CSR); 90 } 91 92 void LiveRegUnits::addPristines(const MachineFunction &MF) { 93 const MachineFrameInfo &MFI = MF.getFrameInfo(); 94 if (!MFI.isCalleeSavedInfoValid()) 95 return; 96 /// This function will usually be called on an empty object, handle this 97 /// as a special case. 98 if (empty()) { 99 /// Add all callee saved regs, then remove the ones that are saved and 100 /// restored. 101 addCalleeSavedRegs(*this, MF); 102 /// Remove the ones that are not saved/restored; they are pristine. 103 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) 104 removeReg(Info.getReg()); 105 return; 106 } 107 /// If a callee-saved register that is not pristine is already present 108 /// in the set, we should make sure that it stays in it. Precompute the 109 /// set of pristine registers in a separate object. 110 /// Add all callee saved regs, then remove the ones that are saved+restored. 111 LiveRegUnits Pristine(*TRI); 112 addCalleeSavedRegs(Pristine, MF); 113 /// Remove the ones that are not saved/restored; they are pristine. 114 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) 115 Pristine.removeReg(Info.getReg()); 116 addUnits(Pristine.getBitVector()); 117 } 118 119 void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) { 120 const MachineFunction &MF = *MBB.getParent(); 121 122 addPristines(MF); 123 124 // To get the live-outs we simply merge the live-ins of all successors. 125 for (const MachineBasicBlock *Succ : MBB.successors()) 126 addBlockLiveIns(*this, *Succ); 127 128 // For the return block: Add all callee saved registers. 129 if (MBB.isReturnBlock()) { 130 const MachineFrameInfo &MFI = MF.getFrameInfo(); 131 if (MFI.isCalleeSavedInfoValid()) 132 addCalleeSavedRegs(*this, MF); 133 } 134 } 135 136 void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) { 137 const MachineFunction &MF = *MBB.getParent(); 138 addPristines(MF); 139 addBlockLiveIns(*this, MBB); 140 } 141