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1 //===-------------- PPCVSXCopy.cpp - VSX Copy Legalization ----------------===//
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2 //
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3 // The LLVM Compiler Infrastructure
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4 //
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5 // This file is distributed under the University of Illinois Open Source
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6 // License. See LICENSE.TXT for details.
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7 //
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8 //===----------------------------------------------------------------------===//
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9 //
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10 // A pass which deals with the complexity of generating legal VSX register
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11 // copies to/from register classes which partially overlap with the VSX
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12 // register file.
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13 //
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14 //===----------------------------------------------------------------------===//
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15
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16 #include "PPCInstrInfo.h"
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17 #include "MCTargetDesc/PPCPredicates.h"
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18 #include "PPC.h"
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19 #include "PPCHazardRecognizers.h"
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20 #include "PPCInstrBuilder.h"
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21 #include "PPCMachineFunctionInfo.h"
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22 #include "PPCTargetMachine.h"
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23 #include "llvm/ADT/STLExtras.h"
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24 #include "llvm/ADT/Statistic.h"
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25 #include "llvm/CodeGen/MachineFrameInfo.h"
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26 #include "llvm/CodeGen/MachineFunctionPass.h"
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27 #include "llvm/CodeGen/MachineInstrBuilder.h"
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28 #include "llvm/CodeGen/MachineMemOperand.h"
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29 #include "llvm/CodeGen/MachineRegisterInfo.h"
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30 #include "llvm/MC/MCAsmInfo.h"
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31 #include "llvm/Support/CommandLine.h"
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32 #include "llvm/Support/Debug.h"
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33 #include "llvm/Support/ErrorHandling.h"
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34 #include "llvm/Support/TargetRegistry.h"
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35 #include "llvm/Support/raw_ostream.h"
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36
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37 using namespace llvm;
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38
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39 #define DEBUG_TYPE "ppc-vsx-copy"
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40
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41 namespace llvm {
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42 void initializePPCVSXCopyPass(PassRegistry&);
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43 }
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44
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45 namespace {
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46 // PPCVSXCopy pass - For copies between VSX registers and non-VSX registers
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47 // (Altivec and scalar floating-point registers), we need to transform the
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48 // copies into subregister copies with other restrictions.
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49 struct PPCVSXCopy : public MachineFunctionPass {
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50 static char ID;
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51 PPCVSXCopy() : MachineFunctionPass(ID) {
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52 initializePPCVSXCopyPass(*PassRegistry::getPassRegistry());
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53 }
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54
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55 const TargetInstrInfo *TII;
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56
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57 bool IsRegInClass(unsigned Reg, const TargetRegisterClass *RC,
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58 MachineRegisterInfo &MRI) {
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59 if (TargetRegisterInfo::isVirtualRegister(Reg)) {
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60 return RC->hasSubClassEq(MRI.getRegClass(Reg));
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61 } else if (RC->contains(Reg)) {
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62 return true;
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63 }
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64
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65 return false;
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66 }
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67
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68 bool IsVSReg(unsigned Reg, MachineRegisterInfo &MRI) {
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69 return IsRegInClass(Reg, &PPC::VSRCRegClass, MRI);
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70 }
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71
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72 bool IsVRReg(unsigned Reg, MachineRegisterInfo &MRI) {
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73 return IsRegInClass(Reg, &PPC::VRRCRegClass, MRI);
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74 }
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75
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76 bool IsF8Reg(unsigned Reg, MachineRegisterInfo &MRI) {
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77 return IsRegInClass(Reg, &PPC::F8RCRegClass, MRI);
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78 }
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79
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95
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80 bool IsVSFReg(unsigned Reg, MachineRegisterInfo &MRI) {
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81 return IsRegInClass(Reg, &PPC::VSFRCRegClass, MRI);
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82 }
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83
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83
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84 protected:
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85 bool processBlock(MachineBasicBlock &MBB) {
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86 bool Changed = false;
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87
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88 MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
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89 for (MachineBasicBlock::iterator I = MBB.begin(), IE = MBB.end();
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90 I != IE; ++I) {
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91 MachineInstr *MI = I;
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92 if (!MI->isFullCopy())
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93 continue;
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94
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95 MachineOperand &DstMO = MI->getOperand(0);
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96 MachineOperand &SrcMO = MI->getOperand(1);
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97
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98 if ( IsVSReg(DstMO.getReg(), MRI) &&
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99 !IsVSReg(SrcMO.getReg(), MRI)) {
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100 // This is a copy *to* a VSX register from a non-VSX register.
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101 Changed = true;
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102
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103 const TargetRegisterClass *SrcRC =
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104 IsVRReg(SrcMO.getReg(), MRI) ? &PPC::VSHRCRegClass :
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105 &PPC::VSLRCRegClass;
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106 assert((IsF8Reg(SrcMO.getReg(), MRI) ||
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95
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107 IsVRReg(SrcMO.getReg(), MRI) ||
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108 IsVSFReg(SrcMO.getReg(), MRI)) &&
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109 "Unknown source for a VSX copy");
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110
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111 unsigned NewVReg = MRI.createVirtualRegister(SrcRC);
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112 BuildMI(MBB, MI, MI->getDebugLoc(),
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113 TII->get(TargetOpcode::SUBREG_TO_REG), NewVReg)
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114 .addImm(1) // add 1, not 0, because there is no implicit clearing
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115 // of the high bits.
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116 .addOperand(SrcMO)
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117 .addImm(IsVRReg(SrcMO.getReg(), MRI) ? PPC::sub_128 :
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118 PPC::sub_64);
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119
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120 // The source of the original copy is now the new virtual register.
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121 SrcMO.setReg(NewVReg);
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122 } else if (!IsVSReg(DstMO.getReg(), MRI) &&
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123 IsVSReg(SrcMO.getReg(), MRI)) {
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124 // This is a copy *from* a VSX register to a non-VSX register.
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125 Changed = true;
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126
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127 const TargetRegisterClass *DstRC =
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128 IsVRReg(DstMO.getReg(), MRI) ? &PPC::VSHRCRegClass :
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129 &PPC::VSLRCRegClass;
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130 assert((IsF8Reg(DstMO.getReg(), MRI) ||
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131 IsVSFReg(DstMO.getReg(), MRI) ||
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132 IsVRReg(DstMO.getReg(), MRI)) &&
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133 "Unknown destination for a VSX copy");
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134
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135 // Copy the VSX value into a new VSX register of the correct subclass.
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136 unsigned NewVReg = MRI.createVirtualRegister(DstRC);
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137 BuildMI(MBB, MI, MI->getDebugLoc(),
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138 TII->get(TargetOpcode::COPY), NewVReg)
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139 .addOperand(SrcMO);
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140
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141 // Transform the original copy into a subregister extraction copy.
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142 SrcMO.setReg(NewVReg);
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143 SrcMO.setSubReg(IsVRReg(DstMO.getReg(), MRI) ? PPC::sub_128 :
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144 PPC::sub_64);
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145 }
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146 }
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147
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148 return Changed;
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149 }
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150
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151 public:
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152 bool runOnMachineFunction(MachineFunction &MF) override {
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153 // If we don't have VSX on the subtarget, don't do anything.
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154 const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
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155 if (!STI.hasVSX())
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156 return false;
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157 TII = STI.getInstrInfo();
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158
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159 bool Changed = false;
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160
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161 for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
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162 MachineBasicBlock &B = *I++;
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163 if (processBlock(B))
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164 Changed = true;
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165 }
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166
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167 return Changed;
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168 }
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169
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170 void getAnalysisUsage(AnalysisUsage &AU) const override {
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171 MachineFunctionPass::getAnalysisUsage(AU);
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172 }
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173 };
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174 }
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175
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176 INITIALIZE_PASS(PPCVSXCopy, DEBUG_TYPE,
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177 "PowerPC VSX Copy Legalization", false, false)
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178
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179 char PPCVSXCopy::ID = 0;
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180 FunctionPass*
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181 llvm::createPPCVSXCopyPass() { return new PPCVSXCopy(); }
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182
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