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;
SystemZCopyPhysRegs()39 SystemZCopyPhysRegs()
40 : MachineFunctionPass(ID), TII(nullptr), MRI(nullptr) {
41 initializeSystemZCopyPhysRegsPass(*PassRegistry::getPassRegistry());
42 }
43
getPassName() const44 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
createSystemZCopyPhysRegsPass(SystemZTargetMachine & TM)64 FunctionPass *llvm::createSystemZCopyPhysRegsPass(SystemZTargetMachine &TM) {
65 return new SystemZCopyPhysRegs();
66 }
67
getAnalysisUsage(AnalysisUsage & AU) const68 void SystemZCopyPhysRegs::getAnalysisUsage(AnalysisUsage &AU) const {
69 AU.setPreservesCFG();
70 MachineFunctionPass::getAnalysisUsage(AU);
71 }
72
visitMBB(MachineBasicBlock & MBB)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
runOnMachineFunction(MachineFunction & F)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
121