1//===-------------- PPCVSXCopy.cpp - VSX Copy Legalization ----------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// A pass which deals with the complexity of generating legal VSX register
11// copies to/from register classes which partially overlap with the VSX
12// register file.
13//
14//===----------------------------------------------------------------------===//
15
16#include "PPCInstrInfo.h"
17#include "MCTargetDesc/PPCPredicates.h"
18#include "PPC.h"
19#include "PPCHazardRecognizers.h"
20#include "PPCInstrBuilder.h"
21#include "PPCMachineFunctionInfo.h"
22#include "PPCTargetMachine.h"
23#include "llvm/ADT/STLExtras.h"
24#include "llvm/ADT/Statistic.h"
25#include "llvm/CodeGen/MachineFrameInfo.h"
26#include "llvm/CodeGen/MachineFunctionPass.h"
27#include "llvm/CodeGen/MachineInstrBuilder.h"
28#include "llvm/CodeGen/MachineMemOperand.h"
29#include "llvm/CodeGen/MachineRegisterInfo.h"
30#include "llvm/MC/MCAsmInfo.h"
31#include "llvm/Support/CommandLine.h"
32#include "llvm/Support/Debug.h"
33#include "llvm/Support/ErrorHandling.h"
34#include "llvm/Support/TargetRegistry.h"
35#include "llvm/Support/raw_ostream.h"
36
37using namespace llvm;
38
39#define DEBUG_TYPE "ppc-vsx-copy"
40
41namespace llvm {
42  void initializePPCVSXCopyPass(PassRegistry&);
43}
44
45namespace {
46  // PPCVSXCopy pass - For copies between VSX registers and non-VSX registers
47  // (Altivec and scalar floating-point registers), we need to transform the
48  // copies into subregister copies with other restrictions.
49  struct PPCVSXCopy : public MachineFunctionPass {
50    static char ID;
51    PPCVSXCopy() : MachineFunctionPass(ID) {
52      initializePPCVSXCopyPass(*PassRegistry::getPassRegistry());
53    }
54
55    const TargetInstrInfo *TII;
56
57    bool IsRegInClass(unsigned Reg, const TargetRegisterClass *RC,
58                      MachineRegisterInfo &MRI) {
59      if (TargetRegisterInfo::isVirtualRegister(Reg)) {
60        return RC->hasSubClassEq(MRI.getRegClass(Reg));
61      } else if (RC->contains(Reg)) {
62        return true;
63      }
64
65      return false;
66    }
67
68    bool IsVSReg(unsigned Reg, MachineRegisterInfo &MRI) {
69      return IsRegInClass(Reg, &PPC::VSRCRegClass, MRI);
70    }
71
72    bool IsVRReg(unsigned Reg, MachineRegisterInfo &MRI) {
73      return IsRegInClass(Reg, &PPC::VRRCRegClass, MRI);
74    }
75
76    bool IsF8Reg(unsigned Reg, MachineRegisterInfo &MRI) {
77      return IsRegInClass(Reg, &PPC::F8RCRegClass, MRI);
78    }
79
80protected:
81    bool processBlock(MachineBasicBlock &MBB) {
82      bool Changed = false;
83
84      MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
85      for (MachineBasicBlock::iterator I = MBB.begin(), IE = MBB.end();
86           I != IE; ++I) {
87        MachineInstr *MI = I;
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 =
100            IsVRReg(SrcMO.getReg(), MRI) ? &PPC::VSHRCRegClass :
101                                           &PPC::VSLRCRegClass;
102          assert((IsF8Reg(SrcMO.getReg(), MRI) ||
103                  IsVRReg(SrcMO.getReg(), MRI)) &&
104                 "Unknown source for a VSX copy");
105
106          unsigned NewVReg = MRI.createVirtualRegister(SrcRC);
107          BuildMI(MBB, MI, MI->getDebugLoc(),
108                  TII->get(TargetOpcode::SUBREG_TO_REG), NewVReg)
109            .addImm(1) // add 1, not 0, because there is no implicit clearing
110                       // of the high bits.
111            .addOperand(SrcMO)
112            .addImm(IsVRReg(SrcMO.getReg(), MRI) ? PPC::sub_128 :
113                                                   PPC::sub_64);
114
115          // The source of the original copy is now the new virtual register.
116          SrcMO.setReg(NewVReg);
117        } else if (!IsVSReg(DstMO.getReg(), MRI) &&
118                    IsVSReg(SrcMO.getReg(), MRI)) {
119          // This is a copy *from* a VSX register to a non-VSX register.
120          Changed = true;
121
122          const TargetRegisterClass *DstRC =
123            IsVRReg(DstMO.getReg(), MRI) ? &PPC::VSHRCRegClass :
124                                           &PPC::VSLRCRegClass;
125          assert((IsF8Reg(DstMO.getReg(), MRI) ||
126                  IsVRReg(DstMO.getReg(), MRI)) &&
127                 "Unknown destination for a VSX copy");
128
129          // Copy the VSX value into a new VSX register of the correct subclass.
130          unsigned NewVReg = MRI.createVirtualRegister(DstRC);
131          BuildMI(MBB, MI, MI->getDebugLoc(),
132                  TII->get(TargetOpcode::COPY), NewVReg)
133            .addOperand(SrcMO);
134
135          // Transform the original copy into a subregister extraction copy.
136          SrcMO.setReg(NewVReg);
137          SrcMO.setSubReg(IsVRReg(DstMO.getReg(), MRI) ? PPC::sub_128 :
138                                                         PPC::sub_64);
139        }
140      }
141
142      return Changed;
143    }
144
145public:
146    bool runOnMachineFunction(MachineFunction &MF) override {
147      // If we don't have VSX on the subtarget, don't do anything.
148      const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
149      if (!STI.hasVSX())
150        return false;
151      TII = STI.getInstrInfo();
152
153      bool Changed = false;
154
155      for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
156        MachineBasicBlock &B = *I++;
157        if (processBlock(B))
158          Changed = true;
159      }
160
161      return Changed;
162    }
163
164    void getAnalysisUsage(AnalysisUsage &AU) const override {
165      MachineFunctionPass::getAnalysisUsage(AU);
166    }
167  };
168}
169
170INITIALIZE_PASS(PPCVSXCopy, DEBUG_TYPE,
171                "PowerPC VSX Copy Legalization", false, false)
172
173char PPCVSXCopy::ID = 0;
174FunctionPass*
175llvm::createPPCVSXCopyPass() { return new PPCVSXCopy(); }
176
177