1//===-------------- PPCVSXCopy.cpp - VSX Copy Legalization ----------------===//
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// A pass which deals with the complexity of generating legal VSX register
10// copies to/from register classes which partially overlap with the VSX
11// register file.
12//
13//===----------------------------------------------------------------------===//
14
15#include "MCTargetDesc/PPCPredicates.h"
16#include "PPC.h"
17#include "PPCHazardRecognizers.h"
18#include "PPCInstrBuilder.h"
19#include "PPCInstrInfo.h"
20#include "PPCMachineFunctionInfo.h"
21#include "PPCTargetMachine.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/CodeGen/MachineFrameInfo.h"
25#include "llvm/CodeGen/MachineFunctionPass.h"
26#include "llvm/CodeGen/MachineInstrBuilder.h"
27#include "llvm/CodeGen/MachineMemOperand.h"
28#include "llvm/CodeGen/MachineRegisterInfo.h"
29#include "llvm/MC/MCAsmInfo.h"
30#include "llvm/MC/TargetRegistry.h"
31#include "llvm/Support/Debug.h"
32#include "llvm/Support/ErrorHandling.h"
33#include "llvm/Support/raw_ostream.h"
34
35using namespace llvm;
36
37#define DEBUG_TYPE "ppc-vsx-copy"
38
39namespace {
40  // PPCVSXCopy pass - For copies between VSX registers and non-VSX registers
41  // (Altivec and scalar floating-point registers), we need to transform the
42  // copies into subregister copies with other restrictions.
43  struct PPCVSXCopy : public MachineFunctionPass {
44    static char ID;
45    PPCVSXCopy() : MachineFunctionPass(ID) {
46      initializePPCVSXCopyPass(*PassRegistry::getPassRegistry());
47    }
48
49    const TargetInstrInfo *TII;
50
51    bool IsRegInClass(unsigned Reg, const TargetRegisterClass *RC,
52                      MachineRegisterInfo &MRI) {
53      if (Register::isVirtualRegister(Reg)) {
54        return RC->hasSubClassEq(MRI.getRegClass(Reg));
55      } else if (RC->contains(Reg)) {
56        return true;
57      }
58
59      return false;
60    }
61
62    bool IsVSReg(unsigned Reg, MachineRegisterInfo &MRI) {
63      return IsRegInClass(Reg, &PPC::VSRCRegClass, MRI);
64    }
65
66    bool IsVRReg(unsigned Reg, MachineRegisterInfo &MRI) {
67      return IsRegInClass(Reg, &PPC::VRRCRegClass, MRI);
68    }
69
70    bool IsF8Reg(unsigned Reg, MachineRegisterInfo &MRI) {
71      return IsRegInClass(Reg, &PPC::F8RCRegClass, MRI);
72    }
73
74    bool IsVSFReg(unsigned Reg, MachineRegisterInfo &MRI) {
75      return IsRegInClass(Reg, &PPC::VSFRCRegClass, MRI);
76    }
77
78    bool IsVSSReg(unsigned Reg, MachineRegisterInfo &MRI) {
79      return IsRegInClass(Reg, &PPC::VSSRCRegClass, MRI);
80    }
81
82protected:
83    bool processBlock(MachineBasicBlock &MBB) {
84      bool Changed = false;
85
86      MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
87      for (MachineInstr &MI : MBB) {
88        if (!MI.isFullCopy())
89          continue;
90
91        MachineOperand &DstMO = MI.getOperand(0);
92        MachineOperand &SrcMO = MI.getOperand(1);
93
94        if ( IsVSReg(DstMO.getReg(), MRI) &&
95            !IsVSReg(SrcMO.getReg(), MRI)) {
96          // This is a copy *to* a VSX register from a non-VSX register.
97          Changed = true;
98
99          const TargetRegisterClass *SrcRC = &PPC::VSLRCRegClass;
100          assert((IsF8Reg(SrcMO.getReg(), MRI) ||
101                  IsVSSReg(SrcMO.getReg(), MRI) ||
102                  IsVSFReg(SrcMO.getReg(), MRI)) &&
103                 "Unknown source for a VSX copy");
104
105          Register NewVReg = MRI.createVirtualRegister(SrcRC);
106          BuildMI(MBB, MI, MI.getDebugLoc(),
107                  TII->get(TargetOpcode::SUBREG_TO_REG), NewVReg)
108              .addImm(1) // add 1, not 0, because there is no implicit clearing
109                         // of the high bits.
110              .add(SrcMO)
111              .addImm(PPC::sub_64);
112
113          // The source of the original copy is now the new virtual register.
114          SrcMO.setReg(NewVReg);
115        } else if (!IsVSReg(DstMO.getReg(), MRI) &&
116                    IsVSReg(SrcMO.getReg(), MRI)) {
117          // This is a copy *from* a VSX register to a non-VSX register.
118          Changed = true;
119
120          const TargetRegisterClass *DstRC = &PPC::VSLRCRegClass;
121          assert((IsF8Reg(DstMO.getReg(), MRI) ||
122                  IsVSFReg(DstMO.getReg(), MRI) ||
123                  IsVSSReg(DstMO.getReg(), MRI)) &&
124                 "Unknown destination for a VSX copy");
125
126          // Copy the VSX value into a new VSX register of the correct subclass.
127          Register NewVReg = MRI.createVirtualRegister(DstRC);
128          BuildMI(MBB, MI, MI.getDebugLoc(), TII->get(TargetOpcode::COPY),
129                  NewVReg)
130              .add(SrcMO);
131
132          // Transform the original copy into a subregister extraction copy.
133          SrcMO.setReg(NewVReg);
134          SrcMO.setSubReg(PPC::sub_64);
135        }
136      }
137
138      return Changed;
139    }
140
141public:
142    bool runOnMachineFunction(MachineFunction &MF) override {
143      // If we don't have VSX on the subtarget, don't do anything.
144      const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
145      if (!STI.hasVSX())
146        return false;
147      TII = STI.getInstrInfo();
148
149      bool Changed = false;
150
151      for (MachineBasicBlock &B : llvm::make_early_inc_range(MF))
152        if (processBlock(B))
153          Changed = true;
154
155      return Changed;
156    }
157
158    void getAnalysisUsage(AnalysisUsage &AU) const override {
159      MachineFunctionPass::getAnalysisUsage(AU);
160    }
161  };
162}
163
164INITIALIZE_PASS(PPCVSXCopy, DEBUG_TYPE,
165                "PowerPC VSX Copy Legalization", false, false)
166
167char PPCVSXCopy::ID = 0;
168FunctionPass*
169llvm::createPPCVSXCopyPass() { return new PPCVSXCopy(); }
170