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 #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 20 using namespace llvm; 21 22 void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) { 23 for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) { 24 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) { 25 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) 26 Units.reset(U); 27 } 28 } 29 } 30 31 void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) { 32 for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) { 33 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) { 34 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) 35 Units.set(U); 36 } 37 } 38 } 39 40 void LiveRegUnits::stepBackward(const MachineInstr &MI) { 41 // Remove defined registers and regmask kills from the set. 42 for (const MachineOperand &MOP : phys_regs_and_masks(MI)) { 43 if (MOP.isRegMask()) { 44 removeRegsNotPreserved(MOP.getRegMask()); 45 continue; 46 } 47 48 if (MOP.isDef()) 49 removeReg(MOP.getReg()); 50 } 51 52 // Add uses to the set. 53 for (const MachineOperand &MOP : phys_regs_and_masks(MI)) { 54 if (!MOP.isReg() || !MOP.readsReg()) 55 continue; 56 addReg(MOP.getReg()); 57 } 58 } 59 60 void LiveRegUnits::accumulate(const MachineInstr &MI) { 61 // Add defs, uses and regmask clobbers to the set. 62 for (const MachineOperand &MOP : phys_regs_and_masks(MI)) { 63 if (MOP.isRegMask()) { 64 addRegsInMask(MOP.getRegMask()); 65 continue; 66 } 67 if (!MOP.isDef() && !MOP.readsReg()) 68 continue; 69 addReg(MOP.getReg()); 70 } 71 } 72 73 /// Add live-in registers of basic block \p MBB to \p LiveUnits. 74 static void addBlockLiveIns(LiveRegUnits &LiveUnits, 75 const MachineBasicBlock &MBB) { 76 for (const auto &LI : MBB.liveins()) 77 LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask); 78 } 79 80 /// Adds all callee saved registers to \p LiveUnits. 81 static void addCalleeSavedRegs(LiveRegUnits &LiveUnits, 82 const MachineFunction &MF) { 83 const MachineRegisterInfo &MRI = MF.getRegInfo(); 84 const MachineFrameInfo &MFI = MF.getFrameInfo(); 85 for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR) { 86 const unsigned N = *CSR; 87 88 const auto &CSI = MFI.getCalleeSavedInfo(); 89 auto Info = 90 llvm::find_if(CSI, [N](auto Info) { return Info.getReg() == N; }); 91 // If we have no info for this callee-saved register, assume it is liveout 92 if (Info == CSI.end() || Info->isRestored()) 93 LiveUnits.addReg(N); 94 } 95 } 96 97 void LiveRegUnits::addPristines(const MachineFunction &MF) { 98 const MachineFrameInfo &MFI = MF.getFrameInfo(); 99 if (!MFI.isCalleeSavedInfoValid()) 100 return; 101 /// This function will usually be called on an empty object, handle this 102 /// as a special case. 103 if (empty()) { 104 /// Add all callee saved regs, then remove the ones that are saved and 105 /// restored. 106 addCalleeSavedRegs(*this, MF); 107 /// Remove the ones that are not saved/restored; they are pristine. 108 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) 109 removeReg(Info.getReg()); 110 return; 111 } 112 /// If a callee-saved register that is not pristine is already present 113 /// in the set, we should make sure that it stays in it. Precompute the 114 /// set of pristine registers in a separate object. 115 /// Add all callee saved regs, then remove the ones that are saved+restored. 116 LiveRegUnits Pristine(*TRI); 117 addCalleeSavedRegs(Pristine, MF); 118 /// Remove the ones that are not saved/restored; they are pristine. 119 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) 120 Pristine.removeReg(Info.getReg()); 121 addUnits(Pristine.getBitVector()); 122 } 123 124 void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) { 125 const MachineFunction &MF = *MBB.getParent(); 126 127 addPristines(MF); 128 129 // To get the live-outs we simply merge the live-ins of all successors. 130 for (const MachineBasicBlock *Succ : MBB.successors()) 131 addBlockLiveIns(*this, *Succ); 132 133 // For the return block: Add all callee saved registers. 134 if (MBB.isReturnBlock()) { 135 const MachineFrameInfo &MFI = MF.getFrameInfo(); 136 if (MFI.isCalleeSavedInfoValid()) 137 addCalleeSavedRegs(*this, MF); 138 } 139 } 140 141 void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) { 142 const MachineFunction &MF = *MBB.getParent(); 143 addPristines(MF); 144 addBlockLiveIns(*this, MBB); 145 } 146