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;
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 
56 FunctionPass *llvm::createSystemZCopyPhysRegsPass(SystemZTargetMachine &TM) {
57   return new SystemZCopyPhysRegs();
58 }
59 
60 void SystemZCopyPhysRegs::getAnalysisUsage(AnalysisUsage &AU) const {
61   AU.setPreservesCFG();
62   MachineFunctionPass::getAnalysisUsage(AU);
63 }
64 
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 
102 bool SystemZCopyPhysRegs::runOnMachineFunction(MachineFunction &F) {
103   TII = static_cast<const SystemZInstrInfo *>(F.getSubtarget().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