llvm/lib/Target/SystemZ/SystemZCopyPhysRegs.cpp

   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 "SystemZMachineFunctionInfo.h"
  17 #include "SystemZTargetMachine.h"
  18 #include "llvm/CodeGen/MachineDominators.h"
  19 #include "llvm/CodeGen/MachineFunctionPass.h"
  20 #include "llvm/CodeGen/MachineInstrBuilder.h"
  21 #include "llvm/CodeGen/MachineRegisterInfo.h"
  22 #include "llvm/CodeGen/TargetInstrInfo.h"
  23 #include "llvm/CodeGen/TargetRegisterInfo.h"
  24 #include "llvm/Target/TargetMachine.h"
  25
  26 using namespace llvm;
  27
  28 #define SYSTEMZ_COPYPHYSREGS_NAME "SystemZ Copy Physregs"
  29
  30 namespace llvm {
  31   void initializeSystemZCopyPhysRegsPass(PassRegistry&);
  32 }
  33
  34 namespace {
  35
  36 class SystemZCopyPhysRegs : public MachineFunctionPass {
  37 public:
  38   static char ID;
  39   SystemZCopyPhysRegs()
  40     : MachineFunctionPass(ID), TII(nullptr), MRI(nullptr) {
  41     initializeSystemZCopyPhysRegsPass(*PassRegistry::getPassRegistry());
  42   }
  43
  44   StringRef getPassName() const override { return SYSTEMZ_COPYPHYSREGS_NAME; }
  45
  46   bool runOnMachineFunction(MachineFunction &MF) override;
  47   void getAnalysisUsage(AnalysisUsage &AU) const override;
  48
  49 private:
  50
  51   bool visitMBB(MachineBasicBlock &MBB);
  52
  53   const SystemZInstrInfo *TII;
  54   MachineRegisterInfo *MRI;
  55 };
  56
  57 char SystemZCopyPhysRegs::ID = 0;
  58
  59 } // end anonymous namespace
  60
  61 INITIALIZE_PASS(SystemZCopyPhysRegs, "systemz-copy-physregs",
  62                 SYSTEMZ_COPYPHYSREGS_NAME, false, false)
  63
  64 FunctionPass *llvm::createSystemZCopyPhysRegsPass(SystemZTargetMachine &TM) {
  65   return new SystemZCopyPhysRegs();
  66 }
  67
  68 void SystemZCopyPhysRegs::getAnalysisUsage(AnalysisUsage &AU) const {
  69   AU.setPreservesCFG();
  70   MachineFunctionPass::getAnalysisUsage(AU);
  71 }
  72
  73 bool SystemZCopyPhysRegs::visitMBB(MachineBasicBlock &MBB) {
  74   bool Modified = false;
  75
  76   // Certain special registers can only be copied from a subset of the
  77   // default register class of the type. It is therefore necessary to create
  78   // the target copy instructions before regalloc instead of in copyPhysReg().
  79   for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
  80        MBBI != E; ) {
  81     MachineInstr *MI = &*MBBI++;
  82     if (!MI->isCopy())
  83       continue;
  84
  85     DebugLoc DL = MI->getDebugLoc();
  86     Register SrcReg = MI->getOperand(1).getReg();
  87     Register DstReg = MI->getOperand(0).getReg();
  88     if (DstReg.isVirtual() &&
  89         (SrcReg == SystemZ::CC || SystemZ::AR32BitRegClass.contains(SrcReg))) {
  90       Register Tmp = MRI->createVirtualRegister(&SystemZ::GR32BitRegClass);
  91       if (SrcReg == SystemZ::CC)
  92         BuildMI(MBB, MI, DL, TII->get(SystemZ::IPM), Tmp);
  93       else
  94         BuildMI(MBB, MI, DL, TII->get(SystemZ::EAR), Tmp).addReg(SrcReg);
  95       MI->getOperand(1).setReg(Tmp);
  96       Modified = true;
  97     }
  98     else if (SrcReg.isVirtual() &&
  99              SystemZ::AR32BitRegClass.contains(DstReg)) {
 100       Register Tmp = MRI->createVirtualRegister(&SystemZ::GR32BitRegClass);
 101       MI->getOperand(0).setReg(Tmp);
 102       BuildMI(MBB, MBBI, DL, TII->get(SystemZ::SAR), DstReg).addReg(Tmp);
 103       Modified = true;
 104     }
 105   }
 106
 107   return Modified;
 108 }
 109
 110 bool SystemZCopyPhysRegs::runOnMachineFunction(MachineFunction &F) {
 111   TII = static_cast<const SystemZInstrInfo *>(F.getSubtarget().getInstrInfo());
 112   MRI = &F.getRegInfo();
 113
 114   bool Modified = false;
 115   for (auto &MBB : F)
 116     Modified |= visitMBB(MBB);
 117
 118   return Modified;
 119 }
 120