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 namespace {
29
30 class SystemZCopyPhysRegs : public MachineFunctionPass {
31 public:
32 static char ID;
SystemZCopyPhysRegs()33 SystemZCopyPhysRegs()
34 : MachineFunctionPass(ID), TII(nullptr), MRI(nullptr) {
35 initializeSystemZCopyPhysRegsPass(*PassRegistry::getPassRegistry());
36 }
37
38 bool runOnMachineFunction(MachineFunction &MF) override;
39 void getAnalysisUsage(AnalysisUsage &AU) const override;
40
41 private:
42
43 bool visitMBB(MachineBasicBlock &MBB);
44
45 const SystemZInstrInfo *TII;
46 MachineRegisterInfo *MRI;
47 };
48
49 char SystemZCopyPhysRegs::ID = 0;
50
51 } // end anonymous namespace
52
53 INITIALIZE_PASS(SystemZCopyPhysRegs, "systemz-copy-physregs",
54 "SystemZ Copy Physregs", false, false)
55
createSystemZCopyPhysRegsPass(SystemZTargetMachine & TM)56 FunctionPass *llvm::createSystemZCopyPhysRegsPass(SystemZTargetMachine &TM) {
57 return new SystemZCopyPhysRegs();
58 }
59
getAnalysisUsage(AnalysisUsage & AU) const60 void SystemZCopyPhysRegs::getAnalysisUsage(AnalysisUsage &AU) const {
61 AU.setPreservesCFG();
62 MachineFunctionPass::getAnalysisUsage(AU);
63 }
64
visitMBB(MachineBasicBlock & MBB)65 bool SystemZCopyPhysRegs::visitMBB(MachineBasicBlock &MBB) {
66 bool Modified = false;
67
68 // Certain special registers can only be copied from a subset of the
69 // default register class of the type. It is therefore necessary to create
70 // the target copy instructions before regalloc instead of in copyPhysReg().
71 for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
72 MBBI != E; ) {
73 MachineInstr *MI = &*MBBI++;
74 if (!MI->isCopy())
75 continue;
76
77 DebugLoc DL = MI->getDebugLoc();
78 Register SrcReg = MI->getOperand(1).getReg();
79 Register DstReg = MI->getOperand(0).getReg();
80 if (DstReg.isVirtual() &&
81 (SrcReg == SystemZ::CC || SystemZ::AR32BitRegClass.contains(SrcReg))) {
82 Register Tmp = MRI->createVirtualRegister(&SystemZ::GR32BitRegClass);
83 if (SrcReg == SystemZ::CC)
84 BuildMI(MBB, MI, DL, TII->get(SystemZ::IPM), Tmp);
85 else
86 BuildMI(MBB, MI, DL, TII->get(SystemZ::EAR), Tmp).addReg(SrcReg);
87 MI->getOperand(1).setReg(Tmp);
88 Modified = true;
89 }
90 else if (SrcReg.isVirtual() &&
91 SystemZ::AR32BitRegClass.contains(DstReg)) {
92 Register Tmp = MRI->createVirtualRegister(&SystemZ::GR32BitRegClass);
93 MI->getOperand(0).setReg(Tmp);
94 BuildMI(MBB, MBBI, DL, TII->get(SystemZ::SAR), DstReg).addReg(Tmp);
95 Modified = true;
96 }
97 }
98
99 return Modified;
100 }
101
runOnMachineFunction(MachineFunction & F)102 bool SystemZCopyPhysRegs::runOnMachineFunction(MachineFunction &F) {
103 TII = F.getSubtarget<SystemZSubtarget>().getInstrInfo();
104 MRI = &F.getRegInfo();
105
106 bool Modified = false;
107 for (auto &MBB : F)
108 Modified |= visitMBB(MBB);
109
110 return Modified;
111 }
112
113