1 //===---------- SystemZPhysRegCopy.cpp - Handle phys reg copies -----------===// 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 // This pass makes sure that a COPY of a physical register will be 10 // implementable after register allocation in copyPhysReg() (this could be 11 // done in EmitInstrWithCustomInserter() instead if COPY instructions would 12 // be passed to it). 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "SystemZTargetMachine.h" 17 #include "llvm/CodeGen/MachineDominators.h" 18 #include "llvm/CodeGen/MachineFunctionPass.h" 19 #include "llvm/CodeGen/MachineInstrBuilder.h" 20 #include "llvm/CodeGen/MachineRegisterInfo.h" 21 #include "llvm/CodeGen/TargetInstrInfo.h" 22 #include "llvm/CodeGen/TargetRegisterInfo.h" 23 24 using namespace llvm; 25 26 namespace { 27 28 class SystemZCopyPhysRegs : public MachineFunctionPass { 29 public: 30 static char ID; 31 SystemZCopyPhysRegs() : MachineFunctionPass(ID), TII(nullptr), MRI(nullptr) {} 32 33 bool runOnMachineFunction(MachineFunction &MF) override; 34 void getAnalysisUsage(AnalysisUsage &AU) const override; 35 36 private: 37 38 bool visitMBB(MachineBasicBlock &MBB); 39 40 const SystemZInstrInfo *TII; 41 MachineRegisterInfo *MRI; 42 }; 43 44 char SystemZCopyPhysRegs::ID = 0; 45 46 } // end anonymous namespace 47 48 INITIALIZE_PASS(SystemZCopyPhysRegs, "systemz-copy-physregs", 49 "SystemZ Copy Physregs", false, false) 50 51 FunctionPass *llvm::createSystemZCopyPhysRegsPass(SystemZTargetMachine &TM) { 52 return new SystemZCopyPhysRegs(); 53 } 54 55 void SystemZCopyPhysRegs::getAnalysisUsage(AnalysisUsage &AU) const { 56 AU.setPreservesCFG(); 57 MachineFunctionPass::getAnalysisUsage(AU); 58 } 59 60 bool SystemZCopyPhysRegs::visitMBB(MachineBasicBlock &MBB) { 61 bool Modified = false; 62 63 // Certain special registers can only be copied from a subset of the 64 // default register class of the type. It is therefore necessary to create 65 // the target copy instructions before regalloc instead of in copyPhysReg(). 66 for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end(); 67 MBBI != E; ) { 68 MachineInstr *MI = &*MBBI++; 69 if (!MI->isCopy()) 70 continue; 71 72 DebugLoc DL = MI->getDebugLoc(); 73 Register SrcReg = MI->getOperand(1).getReg(); 74 Register DstReg = MI->getOperand(0).getReg(); 75 76 if (DstReg.isVirtual() && 77 (SrcReg == SystemZ::CC || SystemZ::AR32BitRegClass.contains(SrcReg))) { 78 Register Tmp = MRI->createVirtualRegister(&SystemZ::GR32BitRegClass); 79 if (SrcReg == SystemZ::CC) 80 BuildMI(MBB, MI, DL, TII->get(SystemZ::IPM), Tmp); 81 else 82 BuildMI(MBB, MI, DL, TII->get(SystemZ::EAR), Tmp).addReg(SrcReg); 83 MI->getOperand(1).setReg(Tmp); 84 Modified = true; 85 } 86 else if (SrcReg.isVirtual() && 87 SystemZ::AR32BitRegClass.contains(DstReg)) { 88 Register Tmp = MRI->createVirtualRegister(&SystemZ::GR32BitRegClass); 89 MI->getOperand(0).setReg(Tmp); 90 MachineInstr *NMI = 91 BuildMI(MBB, MBBI, DL, TII->get(SystemZ::SAR), DstReg).addReg(Tmp); 92 // SAR now writes the final value to DstReg, so update debug values. 93 MBB.getParent()->substituteDebugValuesForInst(*MI, *NMI); 94 Modified = true; 95 } 96 } 97 98 return Modified; 99 } 100 101 bool SystemZCopyPhysRegs::runOnMachineFunction(MachineFunction &F) { 102 TII = F.getSubtarget<SystemZSubtarget>().getInstrInfo(); 103 MRI = &F.getRegInfo(); 104 105 bool Modified = false; 106 for (auto &MBB : F) 107 Modified |= visitMBB(MBB); 108 109 return Modified; 110 } 111 112