lib/Target/PowerPC/PPCVSXCopy.cpp

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