lib/CodeGen/MachineInstrBundle.cpp

   1 //===-- lib/CodeGen/MachineInstrBundle.cpp --------------------------------===//
   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 #include "llvm/CodeGen/MachineInstrBundle.h"
  11 #include "llvm/ADT/SmallSet.h"
  12 #include "llvm/ADT/SmallVector.h"
  13 #include "llvm/CodeGen/MachineFunctionPass.h"
  14 #include "llvm/CodeGen/MachineInstrBuilder.h"
  15 #include "llvm/CodeGen/Passes.h"
  16 #include "llvm/CodeGen/TargetInstrInfo.h"
  17 #include "llvm/CodeGen/TargetRegisterInfo.h"
  18 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  19 #include "llvm/Target/TargetMachine.h"
  20 #include <utility>
  21 using namespace llvm;
  22
  23 namespace {
  24   class UnpackMachineBundles : public MachineFunctionPass {
  25   public:
  26     static char ID; // Pass identification
  27     UnpackMachineBundles(
  28         std::function<bool(const MachineFunction &)> Ftor = nullptr)
  29         : MachineFunctionPass(ID), PredicateFtor(std::move(Ftor)) {
  30       initializeUnpackMachineBundlesPass(*PassRegistry::getPassRegistry());
  31     }
  32
  33     bool runOnMachineFunction(MachineFunction &MF) override;
  34
  35   private:
  36     std::function<bool(const MachineFunction &)> PredicateFtor;
  37   };
  38 } // end anonymous namespace
  39
  40 char UnpackMachineBundles::ID = 0;
  41 char &llvm::UnpackMachineBundlesID = UnpackMachineBundles::ID;
  42 INITIALIZE_PASS(UnpackMachineBundles, "unpack-mi-bundles",
  43                 "Unpack machine instruction bundles", false, false)
  44
  45 bool UnpackMachineBundles::runOnMachineFunction(MachineFunction &MF) {
  46   if (PredicateFtor && !PredicateFtor(MF))
  47     return false;
  48
  49   bool Changed = false;
  50   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
  51     MachineBasicBlock *MBB = &*I;
  52
  53     for (MachineBasicBlock::instr_iterator MII = MBB->instr_begin(),
  54            MIE = MBB->instr_end(); MII != MIE; ) {
  55       MachineInstr *MI = &*MII;
  56
  57       // Remove BUNDLE instruction and the InsideBundle flags from bundled
  58       // instructions.
  59       if (MI->isBundle()) {
  60         while (++MII != MIE && MII->isBundledWithPred()) {
  61           MII->unbundleFromPred();
  62           for (unsigned i = 0, e = MII->getNumOperands(); i != e; ++i) {
  63             MachineOperand &MO = MII->getOperand(i);
  64             if (MO.isReg() && MO.isInternalRead())
  65               MO.setIsInternalRead(false);
  66           }
  67         }
  68         MI->eraseFromParent();
  69
  70         Changed = true;
  71         continue;
  72       }
  73
  74       ++MII;
  75     }
  76   }
  77
  78   return Changed;
  79 }
  80
  81 FunctionPass *
  82 llvm::createUnpackMachineBundles(
  83     std::function<bool(const MachineFunction &)> Ftor) {
  84   return new UnpackMachineBundles(std::move(Ftor));
  85 }
  86
  87 namespace {
  88   class FinalizeMachineBundles : public MachineFunctionPass {
  89   public:
  90     static char ID; // Pass identification
  91     FinalizeMachineBundles() : MachineFunctionPass(ID) {
  92       initializeFinalizeMachineBundlesPass(*PassRegistry::getPassRegistry());
  93     }
  94
  95     bool runOnMachineFunction(MachineFunction &MF) override;
  96   };
  97 } // end anonymous namespace
  98
  99 char FinalizeMachineBundles::ID = 0;
 100 char &llvm::FinalizeMachineBundlesID = FinalizeMachineBundles::ID;
 101 INITIALIZE_PASS(FinalizeMachineBundles, "finalize-mi-bundles",
 102                 "Finalize machine instruction bundles", false, false)
 103
 104 bool FinalizeMachineBundles::runOnMachineFunction(MachineFunction &MF) {
 105   return llvm::finalizeBundles(MF);
 106 }
 107
 108
 109 /// finalizeBundle - Finalize a machine instruction bundle which includes
 110 /// a sequence of instructions starting from FirstMI to LastMI (exclusive).
 111 /// This routine adds a BUNDLE instruction to represent the bundle, it adds
 112 /// IsInternalRead markers to MachineOperands which are defined inside the
 113 /// bundle, and it copies externally visible defs and uses to the BUNDLE
 114 /// instruction.
 115 void llvm::finalizeBundle(MachineBasicBlock &MBB,
 116                           MachineBasicBlock::instr_iterator FirstMI,
 117                           MachineBasicBlock::instr_iterator LastMI) {
 118   assert(FirstMI != LastMI && "Empty bundle?");
 119   MIBundleBuilder Bundle(MBB, FirstMI, LastMI);
 120
 121   MachineFunction &MF = *MBB.getParent();
 122   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
 123   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
 124
 125   MachineInstrBuilder MIB =
 126       BuildMI(MF, FirstMI->getDebugLoc(), TII->get(TargetOpcode::BUNDLE));
 127   Bundle.prepend(MIB);
 128
 129   SmallVector<unsigned, 32> LocalDefs;
 130   SmallSet<unsigned, 32> LocalDefSet;
 131   SmallSet<unsigned, 8> DeadDefSet;
 132   SmallSet<unsigned, 16> KilledDefSet;
 133   SmallVector<unsigned, 8> ExternUses;
 134   SmallSet<unsigned, 8> ExternUseSet;
 135   SmallSet<unsigned, 8> KilledUseSet;
 136   SmallSet<unsigned, 8> UndefUseSet;
 137   SmallVector<MachineOperand*, 4> Defs;
 138   for (; FirstMI != LastMI; ++FirstMI) {
 139     for (unsigned i = 0, e = FirstMI->getNumOperands(); i != e; ++i) {
 140       MachineOperand &MO = FirstMI->getOperand(i);
 141       if (!MO.isReg())
 142         continue;
 143       if (MO.isDef()) {
 144         Defs.push_back(&MO);
 145         continue;
 146       }
 147
 148       unsigned Reg = MO.getReg();
 149       if (!Reg)
 150         continue;
 151       assert(TargetRegisterInfo::isPhysicalRegister(Reg));
 152       if (LocalDefSet.count(Reg)) {
 153         MO.setIsInternalRead();
 154         if (MO.isKill())
 155           // Internal def is now killed.
 156           KilledDefSet.insert(Reg);
 157       } else {
 158         if (ExternUseSet.insert(Reg).second) {
 159           ExternUses.push_back(Reg);
 160           if (MO.isUndef())
 161             UndefUseSet.insert(Reg);
 162         }
 163         if (MO.isKill())
 164           // External def is now killed.
 165           KilledUseSet.insert(Reg);
 166       }
 167     }
 168
 169     for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
 170       MachineOperand &MO = *Defs[i];
 171       unsigned Reg = MO.getReg();
 172       if (!Reg)
 173         continue;
 174
 175       if (LocalDefSet.insert(Reg).second) {
 176         LocalDefs.push_back(Reg);
 177         if (MO.isDead()) {
 178           DeadDefSet.insert(Reg);
 179         }
 180       } else {
 181         // Re-defined inside the bundle, it's no longer killed.
 182         KilledDefSet.erase(Reg);
 183         if (!MO.isDead())
 184           // Previously defined but dead.
 185           DeadDefSet.erase(Reg);
 186       }
 187
 188       if (!MO.isDead()) {
 189         for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
 190           unsigned SubReg = *SubRegs;
 191           if (LocalDefSet.insert(SubReg).second)
 192             LocalDefs.push_back(SubReg);
 193         }
 194       }
 195     }
 196
 197     Defs.clear();
 198   }
 199
 200   SmallSet<unsigned, 32> Added;
 201   for (unsigned i = 0, e = LocalDefs.size(); i != e; ++i) {
 202     unsigned Reg = LocalDefs[i];
 203     if (Added.insert(Reg).second) {
 204       // If it's not live beyond end of the bundle, mark it dead.
 205       bool isDead = DeadDefSet.count(Reg) || KilledDefSet.count(Reg);
 206       MIB.addReg(Reg, getDefRegState(true) | getDeadRegState(isDead) |
 207                  getImplRegState(true));
 208     }
 209   }
 210
 211   for (unsigned i = 0, e = ExternUses.size(); i != e; ++i) {
 212     unsigned Reg = ExternUses[i];
 213     bool isKill = KilledUseSet.count(Reg);
 214     bool isUndef = UndefUseSet.count(Reg);
 215     MIB.addReg(Reg, getKillRegState(isKill) | getUndefRegState(isUndef) |
 216                getImplRegState(true));
 217   }
 218 }
 219
 220 /// finalizeBundle - Same functionality as the previous finalizeBundle except
 221 /// the last instruction in the bundle is not provided as an input. This is
 222 /// used in cases where bundles are pre-determined by marking instructions
 223 /// with 'InsideBundle' marker. It returns the MBB instruction iterator that
 224 /// points to the end of the bundle.
 225 MachineBasicBlock::instr_iterator
 226 llvm::finalizeBundle(MachineBasicBlock &MBB,
 227                      MachineBasicBlock::instr_iterator FirstMI) {
 228   MachineBasicBlock::instr_iterator E = MBB.instr_end();
 229   MachineBasicBlock::instr_iterator LastMI = std::next(FirstMI);
 230   while (LastMI != E && LastMI->isInsideBundle())
 231     ++LastMI;
 232   finalizeBundle(MBB, FirstMI, LastMI);
 233   return LastMI;
 234 }
 235
 236 /// finalizeBundles - Finalize instruction bundles in the specified
 237 /// MachineFunction. Return true if any bundles are finalized.
 238 bool llvm::finalizeBundles(MachineFunction &MF) {
 239   bool Changed = false;
 240   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
 241     MachineBasicBlock &MBB = *I;
 242     MachineBasicBlock::instr_iterator MII = MBB.instr_begin();
 243     MachineBasicBlock::instr_iterator MIE = MBB.instr_end();
 244     if (MII == MIE)
 245       continue;
 246     assert(!MII->isInsideBundle() &&
 247            "First instr cannot be inside bundle before finalization!");
 248
 249     for (++MII; MII != MIE; ) {
 250       if (!MII->isInsideBundle())
 251         ++MII;
 252       else {
 253         MII = finalizeBundle(MBB, std::prev(MII));
 254         Changed = true;
 255       }
 256     }
 257   }
 258
 259   return Changed;
 260 }
 261
 262 //===----------------------------------------------------------------------===//
 263 // MachineOperand iterator
 264 //===----------------------------------------------------------------------===//
 265
 266 MachineOperandIteratorBase::VirtRegInfo
 267 MachineOperandIteratorBase::analyzeVirtReg(unsigned Reg,
 268                     SmallVectorImpl<std::pair<MachineInstr*, unsigned> > *Ops) {
 269   VirtRegInfo RI = { false, false, false };
 270   for(; isValid(); ++*this) {
 271     MachineOperand &MO = deref();
 272     if (!MO.isReg() || MO.getReg() != Reg)
 273       continue;
 274
 275     // Remember each (MI, OpNo) that refers to Reg.
 276     if (Ops)
 277       Ops->push_back(std::make_pair(MO.getParent(), getOperandNo()));
 278
 279     // Both defs and uses can read virtual registers.
 280     if (MO.readsReg()) {
 281       RI.Reads = true;
 282       if (MO.isDef())
 283         RI.Tied = true;
 284     }
 285
 286     // Only defs can write.
 287     if (MO.isDef())
 288       RI.Writes = true;
 289     else if (!RI.Tied && MO.getParent()->isRegTiedToDefOperand(getOperandNo()))
 290       RI.Tied = true;
 291   }
 292   return RI;
 293 }
 294
 295 MachineOperandIteratorBase::PhysRegInfo
 296 MachineOperandIteratorBase::analyzePhysReg(unsigned Reg,
 297                                            const TargetRegisterInfo *TRI) {
 298   bool AllDefsDead = true;
 299   PhysRegInfo PRI = {false, false, false, false, false, false, false, false};
 300
 301   assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
 302          "analyzePhysReg not given a physical register!");
 303   for (; isValid(); ++*this) {
 304     MachineOperand &MO = deref();
 305
 306     if (MO.isRegMask() && MO.clobbersPhysReg(Reg)) {
 307       PRI.Clobbered = true;
 308       continue;
 309     }
 310
 311     if (!MO.isReg())
 312       continue;
 313
 314     unsigned MOReg = MO.getReg();
 315     if (!MOReg || !TargetRegisterInfo::isPhysicalRegister(MOReg))
 316       continue;
 317
 318     if (!TRI->regsOverlap(MOReg, Reg))
 319       continue;
 320
 321     bool Covered = TRI->isSuperRegisterEq(Reg, MOReg);
 322     if (MO.readsReg()) {
 323       PRI.Read = true;
 324       if (Covered) {
 325         PRI.FullyRead = true;
 326         if (MO.isKill())
 327           PRI.Killed = true;
 328       }
 329     } else if (MO.isDef()) {
 330       PRI.Defined = true;
 331       if (Covered)
 332         PRI.FullyDefined = true;
 333       if (!MO.isDead())
 334         AllDefsDead = false;
 335     }
 336   }
 337
 338   if (AllDefsDead) {
 339     if (PRI.FullyDefined || PRI.Clobbered)
 340       PRI.DeadDef = true;
 341     else if (PRI.Defined)
 342       PRI.PartialDeadDef = true;
 343   }
 344
 345   return PRI;
 346 }