1 //===- LiveRegUnits.cpp - Register Unit Set -------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 /// \file This file imlements the LiveRegUnits set. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/CodeGen/LiveRegUnits.h" 15 16 #include "llvm/CodeGen/MachineBasicBlock.h" 17 #include "llvm/CodeGen/MachineFrameInfo.h" 18 #include "llvm/CodeGen/MachineFunction.h" 19 #include "llvm/CodeGen/MachineInstrBundle.h" 20 #include "llvm/CodeGen/MachineOperand.h" 21 #include "llvm/CodeGen/MachineRegisterInfo.h" 22 #include "llvm/MC/MCRegisterInfo.h" 23 #include "llvm/Target/TargetRegisterInfo.h" 24 25 using namespace llvm; 26 27 void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) { 28 for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) { 29 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) { 30 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) 31 Units.reset(U); 32 } 33 } 34 } 35 36 void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) { 37 for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) { 38 for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) { 39 if (MachineOperand::clobbersPhysReg(RegMask, *RootReg)) 40 Units.set(U); 41 } 42 } 43 } 44 45 void LiveRegUnits::stepBackward(const MachineInstr &MI) { 46 // Remove defined registers and regmask kills from the set. 47 for (ConstMIBundleOperands O(MI); O.isValid(); ++O) { 48 if (O->isReg()) { 49 if (!O->isDef()) 50 continue; 51 unsigned Reg = O->getReg(); 52 if (!TargetRegisterInfo::isPhysicalRegister(Reg)) 53 continue; 54 removeReg(Reg); 55 } else if (O->isRegMask()) 56 removeRegsNotPreserved(O->getRegMask()); 57 } 58 59 // Add uses to the set. 60 for (ConstMIBundleOperands O(MI); O.isValid(); ++O) { 61 if (!O->isReg() || !O->readsReg()) 62 continue; 63 unsigned Reg = O->getReg(); 64 if (!TargetRegisterInfo::isPhysicalRegister(Reg)) 65 continue; 66 addReg(Reg); 67 } 68 } 69 70 void LiveRegUnits::accumulate(const MachineInstr &MI) { 71 // Add defs, uses and regmask clobbers to the set. 72 for (ConstMIBundleOperands O(MI); O.isValid(); ++O) { 73 if (O->isReg()) { 74 unsigned Reg = O->getReg(); 75 if (!TargetRegisterInfo::isPhysicalRegister(Reg)) 76 continue; 77 if (!O->isDef() && !O->readsReg()) 78 continue; 79 addReg(Reg); 80 } else if (O->isRegMask()) 81 addRegsInMask(O->getRegMask()); 82 } 83 } 84 85 /// Add live-in registers of basic block \p MBB to \p LiveUnits. 86 static void addBlockLiveIns(LiveRegUnits &LiveUnits, 87 const MachineBasicBlock &MBB) { 88 for (const auto &LI : MBB.liveins()) 89 LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask); 90 } 91 92 /// Adds all callee saved registers to \p LiveUnits. 93 static void addCalleeSavedRegs(LiveRegUnits &LiveUnits, 94 const MachineFunction &MF) { 95 const MachineRegisterInfo &MRI = MF.getRegInfo(); 96 for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR) 97 LiveUnits.addReg(*CSR); 98 } 99 100 /// Adds pristine registers to the given \p LiveUnits. Pristine registers are 101 /// callee saved registers that are unused in the function. 102 static void addPristines(LiveRegUnits &LiveUnits, const MachineFunction &MF) { 103 const MachineFrameInfo &MFI = MF.getFrameInfo(); 104 if (!MFI.isCalleeSavedInfoValid()) 105 return; 106 /// Add all callee saved regs, then remove the ones that are saved+restored. 107 addCalleeSavedRegs(LiveUnits, MF); 108 /// Remove the ones that are not saved/restored; they are pristine. 109 for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) 110 LiveUnits.removeReg(Info.getReg()); 111 } 112 113 void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) { 114 const MachineFunction &MF = *MBB.getParent(); 115 if (!MBB.succ_empty()) { 116 addPristines(*this, MF); 117 // To get the live-outs we simply merge the live-ins of all successors. 118 for (const MachineBasicBlock *Succ : MBB.successors()) 119 addBlockLiveIns(*this, *Succ); 120 } else if (MBB.isReturnBlock()) { 121 // For the return block: Add all callee saved registers. 122 const MachineFrameInfo &MFI = MF.getFrameInfo(); 123 if (MFI.isCalleeSavedInfoValid()) 124 addCalleeSavedRegs(*this, MF); 125 } 126 } 127 128 void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) { 129 const MachineFunction &MF = *MBB.getParent(); 130 addPristines(*this, MF); 131 addBlockLiveIns(*this, MBB); 132 } 133