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 /// Return the first found DebugLoc that has a DILocation, given a range of
 109 /// instructions. The search range is from FirstMI to LastMI (exclusive). If no
 110 /// DILocation is found, then an empty location is returned.
 111 static DebugLoc getDebugLoc(MachineBasicBlock::instr_iterator FirstMI,
 112                             MachineBasicBlock::instr_iterator LastMI) {
 113   for (auto MII = FirstMI; MII != LastMI; ++MII)
 114     if (MII->getDebugLoc().get())
 115       return MII->getDebugLoc();
 116   return DebugLoc();
 117 }
 118
 119 /// finalizeBundle - Finalize a machine instruction bundle which includes
 120 /// a sequence of instructions starting from FirstMI to LastMI (exclusive).
 121 /// This routine adds a BUNDLE instruction to represent the bundle, it adds
 122 /// IsInternalRead markers to MachineOperands which are defined inside the
 123 /// bundle, and it copies externally visible defs and uses to the BUNDLE
 124 /// instruction.
 125 void llvm::finalizeBundle(MachineBasicBlock &MBB,
 126                           MachineBasicBlock::instr_iterator FirstMI,
 127                           MachineBasicBlock::instr_iterator LastMI) {
 128   assert(FirstMI != LastMI && "Empty bundle?");
 129   MIBundleBuilder Bundle(MBB, FirstMI, LastMI);
 130
 131   MachineFunction &MF = *MBB.getParent();
 132   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
 133   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
 134
 135   MachineInstrBuilder MIB =
 136       BuildMI(MF, getDebugLoc(FirstMI, LastMI), TII->get(TargetOpcode::BUNDLE));
 137   Bundle.prepend(MIB);
 138
 139   SmallVector<unsigned, 32> LocalDefs;
 140   SmallSet<unsigned, 32> LocalDefSet;
 141   SmallSet<unsigned, 8> DeadDefSet;
 142   SmallSet<unsigned, 16> KilledDefSet;
 143   SmallVector<unsigned, 8> ExternUses;
 144   SmallSet<unsigned, 8> ExternUseSet;
 145   SmallSet<unsigned, 8> KilledUseSet;
 146   SmallSet<unsigned, 8> UndefUseSet;
 147   SmallVector<MachineOperand*, 4> Defs;
 148   for (auto MII = FirstMI; MII != LastMI; ++MII) {
 149     for (unsigned i = 0, e = MII->getNumOperands(); i != e; ++i) {
 150       MachineOperand &MO = MII->getOperand(i);
 151       if (!MO.isReg())
 152         continue;
 153       if (MO.isDef()) {
 154         Defs.push_back(&MO);
 155         continue;
 156       }
 157
 158       unsigned Reg = MO.getReg();
 159       if (!Reg)
 160         continue;
 161       assert(TargetRegisterInfo::isPhysicalRegister(Reg));
 162       if (LocalDefSet.count(Reg)) {
 163         MO.setIsInternalRead();
 164         if (MO.isKill())
 165           // Internal def is now killed.
 166           KilledDefSet.insert(Reg);
 167       } else {
 168         if (ExternUseSet.insert(Reg).second) {
 169           ExternUses.push_back(Reg);
 170           if (MO.isUndef())
 171             UndefUseSet.insert(Reg);
 172         }
 173         if (MO.isKill())
 174           // External def is now killed.
 175           KilledUseSet.insert(Reg);
 176       }
 177     }
 178
 179     for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
 180       MachineOperand &MO = *Defs[i];
 181       unsigned Reg = MO.getReg();
 182       if (!Reg)
 183         continue;
 184
 185       if (LocalDefSet.insert(Reg).second) {
 186         LocalDefs.push_back(Reg);
 187         if (MO.isDead()) {
 188           DeadDefSet.insert(Reg);
 189         }
 190       } else {
 191         // Re-defined inside the bundle, it's no longer killed.
 192         KilledDefSet.erase(Reg);
 193         if (!MO.isDead())
 194           // Previously defined but dead.
 195           DeadDefSet.erase(Reg);
 196       }
 197
 198       if (!MO.isDead()) {
 199         for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
 200           unsigned SubReg = *SubRegs;
 201           if (LocalDefSet.insert(SubReg).second)
 202             LocalDefs.push_back(SubReg);
 203         }
 204       }
 205     }
 206
 207     Defs.clear();
 208   }
 209
 210   SmallSet<unsigned, 32> Added;
 211   for (unsigned i = 0, e = LocalDefs.size(); i != e; ++i) {
 212     unsigned Reg = LocalDefs[i];
 213     if (Added.insert(Reg).second) {
 214       // If it's not live beyond end of the bundle, mark it dead.
 215       bool isDead = DeadDefSet.count(Reg) || KilledDefSet.count(Reg);
 216       MIB.addReg(Reg, getDefRegState(true) | getDeadRegState(isDead) |
 217                  getImplRegState(true));
 218     }
 219   }
 220
 221   for (unsigned i = 0, e = ExternUses.size(); i != e; ++i) {
 222     unsigned Reg = ExternUses[i];
 223     bool isKill = KilledUseSet.count(Reg);
 224     bool isUndef = UndefUseSet.count(Reg);
 225     MIB.addReg(Reg, getKillRegState(isKill) | getUndefRegState(isUndef) |
 226                getImplRegState(true));
 227   }
 228
 229   // Set FrameSetup/FrameDestroy for the bundle. If any of the instructions got
 230   // the property, then also set it on the bundle.
 231   for (auto MII = FirstMI; MII != LastMI; ++MII) {
 232     if (MII->getFlag(MachineInstr::FrameSetup))
 233       MIB.setMIFlag(MachineInstr::FrameSetup);
 234     if (MII->getFlag(MachineInstr::FrameDestroy))
 235       MIB.setMIFlag(MachineInstr::FrameDestroy);
 236   }
 237 }
 238
 239 /// finalizeBundle - Same functionality as the previous finalizeBundle except
 240 /// the last instruction in the bundle is not provided as an input. This is
 241 /// used in cases where bundles are pre-determined by marking instructions
 242 /// with 'InsideBundle' marker. It returns the MBB instruction iterator that
 243 /// points to the end of the bundle.
 244 MachineBasicBlock::instr_iterator
 245 llvm::finalizeBundle(MachineBasicBlock &MBB,
 246                      MachineBasicBlock::instr_iterator FirstMI) {
 247   MachineBasicBlock::instr_iterator E = MBB.instr_end();
 248   MachineBasicBlock::instr_iterator LastMI = std::next(FirstMI);
 249   while (LastMI != E && LastMI->isInsideBundle())
 250     ++LastMI;
 251   finalizeBundle(MBB, FirstMI, LastMI);
 252   return LastMI;
 253 }
 254
 255 /// finalizeBundles - Finalize instruction bundles in the specified
 256 /// MachineFunction. Return true if any bundles are finalized.
 257 bool llvm::finalizeBundles(MachineFunction &MF) {
 258   bool Changed = false;
 259   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
 260     MachineBasicBlock &MBB = *I;
 261     MachineBasicBlock::instr_iterator MII = MBB.instr_begin();
 262     MachineBasicBlock::instr_iterator MIE = MBB.instr_end();
 263     if (MII == MIE)
 264       continue;
 265     assert(!MII->isInsideBundle() &&
 266            "First instr cannot be inside bundle before finalization!");
 267
 268     for (++MII; MII != MIE; ) {
 269       if (!MII->isInsideBundle())
 270         ++MII;
 271       else {
 272         MII = finalizeBundle(MBB, std::prev(MII));
 273         Changed = true;
 274       }
 275     }
 276   }
 277
 278   return Changed;
 279 }
 280
 281 //===----------------------------------------------------------------------===//
 282 // MachineOperand iterator
 283 //===----------------------------------------------------------------------===//
 284
 285 MachineOperandIteratorBase::VirtRegInfo
 286 MachineOperandIteratorBase::analyzeVirtReg(unsigned Reg,
 287                     SmallVectorImpl<std::pair<MachineInstr*, unsigned> > *Ops) {
 288   VirtRegInfo RI = { false, false, false };
 289   for(; isValid(); ++*this) {
 290     MachineOperand &MO = deref();
 291     if (!MO.isReg() || MO.getReg() != Reg)
 292       continue;
 293
 294     // Remember each (MI, OpNo) that refers to Reg.
 295     if (Ops)
 296       Ops->push_back(std::make_pair(MO.getParent(), getOperandNo()));
 297
 298     // Both defs and uses can read virtual registers.
 299     if (MO.readsReg()) {
 300       RI.Reads = true;
 301       if (MO.isDef())
 302         RI.Tied = true;
 303     }
 304
 305     // Only defs can write.
 306     if (MO.isDef())
 307       RI.Writes = true;
 308     else if (!RI.Tied && MO.getParent()->isRegTiedToDefOperand(getOperandNo()))
 309       RI.Tied = true;
 310   }
 311   return RI;
 312 }
 313
 314 MachineOperandIteratorBase::PhysRegInfo
 315 MachineOperandIteratorBase::analyzePhysReg(unsigned Reg,
 316                                            const TargetRegisterInfo *TRI) {
 317   bool AllDefsDead = true;
 318   PhysRegInfo PRI = {false, false, false, false, false, false, false, false};
 319
 320   assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
 321          "analyzePhysReg not given a physical register!");
 322   for (; isValid(); ++*this) {
 323     MachineOperand &MO = deref();
 324
 325     if (MO.isRegMask() && MO.clobbersPhysReg(Reg)) {
 326       PRI.Clobbered = true;
 327       continue;
 328     }
 329
 330     if (!MO.isReg())
 331       continue;
 332
 333     unsigned MOReg = MO.getReg();
 334     if (!MOReg || !TargetRegisterInfo::isPhysicalRegister(MOReg))
 335       continue;
 336
 337     if (!TRI->regsOverlap(MOReg, Reg))
 338       continue;
 339
 340     bool Covered = TRI->isSuperRegisterEq(Reg, MOReg);
 341     if (MO.readsReg()) {
 342       PRI.Read = true;
 343       if (Covered) {
 344         PRI.FullyRead = true;
 345         if (MO.isKill())
 346           PRI.Killed = true;
 347       }
 348     } else if (MO.isDef()) {
 349       PRI.Defined = true;
 350       if (Covered)
 351         PRI.FullyDefined = true;
 352       if (!MO.isDead())
 353         AllDefsDead = false;
 354     }
 355   }
 356
 357   if (AllDefsDead) {
 358     if (PRI.FullyDefined || PRI.Clobbered)
 359       PRI.DeadDef = true;
 360     else if (PRI.Defined)
 361       PRI.PartialDeadDef = true;
 362   }
 363
 364   return PRI;
 365 }