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