Example #1
0
/// runOnMachineFunction - Loop over all of the basic blocks, inserting
/// vzero upper instructions before function calls.
bool VZeroUpperInserter::runOnMachineFunction(MachineFunction &MF) {
  if (MF.getTarget().getSubtarget<X86Subtarget>().hasAVX512())
    return false;
  TII = MF.getTarget().getInstrInfo();
  MachineRegisterInfo &MRI = MF.getRegInfo();
  bool EverMadeChange = false;

  // Fast check: if the function doesn't use any ymm registers, we don't need
  // to insert any VZEROUPPER instructions.  This is constant-time, so it is
  // cheap in the common case of no ymm use.
  bool YMMUsed = false;
  const TargetRegisterClass *RC = &X86::VR256RegClass;
  for (TargetRegisterClass::iterator i = RC->begin(), e = RC->end();
       i != e; i++) {
    if (!MRI.reg_nodbg_empty(*i)) {
      YMMUsed = true;
      break;
    }
  }
  if (!YMMUsed)
    return EverMadeChange;

  // Pre-compute the existence of any live-in YMM registers to this function
  FnHasLiveInYmm = checkFnHasLiveInYmm(MRI);

  assert(BBState.empty());
  BBState.resize(MF.getNumBlockIDs(), 0);
  BBSolved.resize(MF.getNumBlockIDs(), 0);

  // Each BB state depends on all predecessors, loop over until everything
  // converges.  (Once we converge, we can implicitly mark everything that is
  // still ST_UNKNOWN as ST_CLEAN.)
  while (1) {
    bool MadeChange = false;

    // Process all basic blocks.
    for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
      MadeChange |= processBasicBlock(MF, *I);

    // If this iteration over the code changed anything, keep iterating.
    if (!MadeChange) break;
    EverMadeChange = true;
  }

  BBState.clear();
  BBSolved.clear();
  return EverMadeChange;
}
bool Thumb2SizeReduce::runOnMachineFunction(MachineFunction &MF) {
  if (PredicateFtor && !PredicateFtor(*MF.getFunction()))
    return false;

  STI = &static_cast<const ARMSubtarget &>(MF.getSubtarget());
  if (STI->isThumb1Only() || STI->prefers32BitThumb())
    return false;

  TII = static_cast<const Thumb2InstrInfo *>(STI->getInstrInfo());

  // Optimizing / minimizing size?
  OptimizeSize = MF.getFunction()->hasFnAttribute(Attribute::OptimizeForSize);
  MinimizeSize = MF.getFunction()->hasFnAttribute(Attribute::MinSize);

  BlockInfo.clear();
  BlockInfo.resize(MF.getNumBlockIDs());

  // Visit blocks in reverse post-order so LastCPSRDef is known for all
  // predecessors.
  ReversePostOrderTraversal<MachineFunction*> RPOT(&MF);
  bool Modified = false;
  for (ReversePostOrderTraversal<MachineFunction*>::rpo_iterator
       I = RPOT.begin(), E = RPOT.end(); I != E; ++I)
    Modified |= ReduceMBB(**I);
  return Modified;
}
/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
/// register references and actual offsets.
///
void PEI::replaceFrameIndices(MachineFunction &Fn) {
  if (!Fn.getFrameInfo()->hasStackObjects()) return; // Nothing to do?

  // Store SPAdj at exit of a basic block.
  SmallVector<int, 8> SPState;
  SPState.resize(Fn.getNumBlockIDs());
  SmallPtrSet<MachineBasicBlock*, 8> Reachable;

  // Iterate over the reachable blocks in DFS order.
  for (df_ext_iterator<MachineFunction*, SmallPtrSet<MachineBasicBlock*, 8> >
       DFI = df_ext_begin(&Fn, Reachable), DFE = df_ext_end(&Fn, Reachable);
       DFI != DFE; ++DFI) {
    int SPAdj = 0;
    // Check the exit state of the DFS stack predecessor.
    if (DFI.getPathLength() >= 2) {
      MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2);
      assert(Reachable.count(StackPred) &&
             "DFS stack predecessor is already visited.\n");
      SPAdj = SPState[StackPred->getNumber()];
    }
    MachineBasicBlock *BB = *DFI;
    replaceFrameIndices(BB, Fn, SPAdj);
    SPState[BB->getNumber()] = SPAdj;
  }

  // Handle the unreachable blocks.
  for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
    if (Reachable.count(BB))
      // Already handled in DFS traversal.
      continue;
    int SPAdj = 0;
    replaceFrameIndices(BB, Fn, SPAdj);
  }
}
/// Colorslots - Color all spill stack slots and rewrite all frameindex machine
/// operands in the function.
bool StackSlotColoring::ColorSlots(MachineFunction &MF) {
  unsigned NumObjs = MFI->getObjectIndexEnd();
  SmallVector<int, 16> SlotMapping(NumObjs, -1);
  SmallVector<float, 16> SlotWeights(NumObjs, 0.0);
  SmallVector<SmallVector<int, 4>, 16> RevMap(NumObjs);
  BitVector UsedColors(NumObjs);

  DEBUG(dbgs() << "Color spill slot intervals:\n");
  bool Changed = false;
  for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
    LiveInterval *li = SSIntervals[i];
    int SS = TargetRegisterInfo::stackSlot2Index(li->reg);
    int NewSS = ColorSlot(li);
    assert(NewSS >= 0 && "Stack coloring failed?");
    SlotMapping[SS] = NewSS;
    RevMap[NewSS].push_back(SS);
    SlotWeights[NewSS] += li->weight;
    UsedColors.set(NewSS);
    Changed |= (SS != NewSS);
  }

  DEBUG(dbgs() << "\nSpill slots after coloring:\n");
  for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
    LiveInterval *li = SSIntervals[i];
    int SS = TargetRegisterInfo::stackSlot2Index(li->reg);
    li->weight = SlotWeights[SS];
  }
  // Sort them by new weight.
  std::stable_sort(SSIntervals.begin(), SSIntervals.end(), IntervalSorter());

#ifndef NDEBUG
  for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i)
    DEBUG(SSIntervals[i]->dump());
  DEBUG(dbgs() << '\n');
#endif

  if (!Changed)
    return false;

  // Rewrite all MO_FrameIndex operands.
  SmallVector<SmallSet<unsigned, 4>, 4> NewDefs(MF.getNumBlockIDs());
  for (unsigned SS = 0, SE = SSRefs.size(); SS != SE; ++SS) {
    int NewFI = SlotMapping[SS];
    if (NewFI == -1 || (NewFI == (int)SS))
      continue;

    SmallVector<MachineInstr*, 8> &RefMIs = SSRefs[SS];
    for (unsigned i = 0, e = RefMIs.size(); i != e; ++i)
      RewriteInstruction(RefMIs[i], SS, NewFI, MF);
  }

  // Delete unused stack slots.
  while (NextColor != -1) {
    DEBUG(dbgs() << "Removing unused stack object fi#" << NextColor << "\n");
    MFI->RemoveStackObject(NextColor);
    NextColor = AllColors.find_next(NextColor);
  }

  return true;
}
Example #5
0
bool SpillPlacement::runOnMachineFunction(MachineFunction &mf) {
  MF = &mf;
  bundles = &getAnalysis<EdgeBundles>();
  loops = &getAnalysis<MachineLoopInfo>();

  assert(!nodes && "Leaking node array");
  nodes = new Node[bundles->getNumBundles()];

  // Compute total ingoing and outgoing block frequencies for all bundles.
  BlockFrequency.resize(mf.getNumBlockIDs());
  for (MachineFunction::iterator I = mf.begin(), E = mf.end(); I != E; ++I) {
    float Freq = LiveIntervals::getSpillWeight(true, false,
                                               loops->getLoopDepth(I));
    unsigned Num = I->getNumber();
    BlockFrequency[Num] = Freq;
    nodes[bundles->getBundle(Num, 1)].Scale[0] += Freq;
    nodes[bundles->getBundle(Num, 0)].Scale[1] += Freq;
  }

  // Scales are reciprocal frequencies.
  for (unsigned i = 0, e = bundles->getNumBundles(); i != e; ++i)
    for (unsigned d = 0; d != 2; ++d)
      if (nodes[i].Scale[d] > 0)
        nodes[i].Scale[d] = 1 / nodes[i].Scale[d];

  // We never change the function.
  return false;
}
Example #6
0
/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
/// register references and actual offsets.
void PEI::replaceFrameIndices(MachineFunction &MF) {
  const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering();
  if (!TFI.needsFrameIndexResolution(MF)) return;

  // Store SPAdj at exit of a basic block.
  SmallVector<int, 8> SPState;
  SPState.resize(MF.getNumBlockIDs());
  df_iterator_default_set<MachineBasicBlock*> Reachable;

  // Iterate over the reachable blocks in DFS order.
  for (auto DFI = df_ext_begin(&MF, Reachable), DFE = df_ext_end(&MF, Reachable);
       DFI != DFE; ++DFI) {
    int SPAdj = 0;
    // Check the exit state of the DFS stack predecessor.
    if (DFI.getPathLength() >= 2) {
      MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2);
      assert(Reachable.count(StackPred) &&
             "DFS stack predecessor is already visited.\n");
      SPAdj = SPState[StackPred->getNumber()];
    }
    MachineBasicBlock *BB = *DFI;
    replaceFrameIndices(BB, MF, SPAdj);
    SPState[BB->getNumber()] = SPAdj;
  }

  // Handle the unreachable blocks.
  for (auto &BB : MF) {
    if (Reachable.count(&BB))
      // Already handled in DFS traversal.
      continue;
    int SPAdj = 0;
    replaceFrameIndices(&BB, MF, SPAdj);
  }
}
Example #7
0
/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
/// register references and actual offsets.
///
void PEI::replaceFrameIndices(MachineFunction &Fn) {
  const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering();
  if (!TFI.needsFrameIndexResolution(Fn)) return;

  MachineModuleInfo &MMI = Fn.getMMI();
  const Function *F = Fn.getFunction();
  const Function *ParentF = MMI.getWinEHParent(F);
  unsigned FrameReg;
  if (F == ParentF) {
    WinEHFuncInfo &FuncInfo = MMI.getWinEHFuncInfo(Fn.getFunction());
    // FIXME: This should be unconditional but we have bugs in the preparation
    // pass.
    if (FuncInfo.UnwindHelpFrameIdx != INT_MAX)
      FuncInfo.UnwindHelpFrameOffset = TFI.getFrameIndexReferenceFromSP(
          Fn, FuncInfo.UnwindHelpFrameIdx, FrameReg);
    for (WinEHTryBlockMapEntry &TBME : FuncInfo.TryBlockMap) {
      for (WinEHHandlerType &H : TBME.HandlerArray) {
        unsigned UnusedReg;
        if (H.CatchObj.FrameIndex == INT_MAX)
          H.CatchObj.FrameOffset = INT_MAX;
        else
          H.CatchObj.FrameOffset =
              TFI.getFrameIndexReference(Fn, H.CatchObj.FrameIndex, UnusedReg);
      }
    }
  }

  // Store SPAdj at exit of a basic block.
  SmallVector<int, 8> SPState;
  SPState.resize(Fn.getNumBlockIDs());
  SmallPtrSet<MachineBasicBlock*, 8> Reachable;

  // Iterate over the reachable blocks in DFS order.
  for (auto DFI = df_ext_begin(&Fn, Reachable), DFE = df_ext_end(&Fn, Reachable);
       DFI != DFE; ++DFI) {
    int SPAdj = 0;
    // Check the exit state of the DFS stack predecessor.
    if (DFI.getPathLength() >= 2) {
      MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2);
      assert(Reachable.count(StackPred) &&
             "DFS stack predecessor is already visited.\n");
      SPAdj = SPState[StackPred->getNumber()];
    }
    MachineBasicBlock *BB = *DFI;
    replaceFrameIndices(BB, Fn, SPAdj);
    SPState[BB->getNumber()] = SPAdj;
  }

  // Handle the unreachable blocks.
  for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
    if (Reachable.count(BB))
      // Already handled in DFS traversal.
      continue;
    int SPAdj = 0;
    replaceFrameIndices(BB, Fn, SPAdj);
  }
}
/// Insert LOOP and BLOCK markers at appropriate places.
static void PlaceMarkers(MachineFunction &MF, const MachineLoopInfo &MLI,
                         const WebAssemblyInstrInfo &TII,
                         MachineDominatorTree &MDT) {
  // For each block whose label represents the end of a scope, record the block
  // which holds the beginning of the scope. This will allow us to quickly skip
  // over scoped regions when walking blocks. We allocate one more than the
  // number of blocks in the function to accommodate for the possible fake block
  // we may insert at the end.
  SmallVector<MachineBasicBlock *, 8> ScopeTops(MF.getNumBlockIDs() + 1);

  for (auto &MBB : MF) {
    // Place the LOOP for MBB if MBB is the header of a loop.
    PlaceLoopMarker(MBB, MF, ScopeTops, TII, MLI);

    // Place the BLOCK for MBB if MBB is branched to from above.
    PlaceBlockMarker(MBB, MF, ScopeTops, TII, MLI, MDT);
  }
}
Example #9
0
bool SpillPlacement::runOnMachineFunction(MachineFunction &mf) {
  MF = &mf;
  bundles = &getAnalysis<EdgeBundles>();
  loops = &getAnalysis<MachineLoopInfo>();

  assert(!nodes && "Leaking node array");
  nodes = new Node[bundles->getNumBundles()];

  // Compute total ingoing and outgoing block frequencies for all bundles.
  BlockFrequencies.resize(mf.getNumBlockIDs());
  MachineBlockFrequencyInfo &MBFI = getAnalysis<MachineBlockFrequencyInfo>();
  for (MachineFunction::iterator I = mf.begin(), E = mf.end(); I != E; ++I) {
    unsigned Num = I->getNumber();
    BlockFrequencies[Num] = MBFI.getBlockFreq(I);
  }

  // We never change the function.
  return false;
}
Example #10
0
/// Check if the CFG of \p MF is irreducible.
static bool isIrreducibleCFG(const MachineFunction &MF,
                             const MachineLoopInfo &MLI) {
  const MachineBasicBlock *Entry = &*MF.begin();
  ReversePostOrderTraversal<const MachineBasicBlock *> RPOT(Entry);
  BitVector VisitedBB(MF.getNumBlockIDs());
  for (const MachineBasicBlock *MBB : RPOT) {
    VisitedBB.set(MBB->getNumber());
    for (const MachineBasicBlock *SuccBB : MBB->successors()) {
      if (!VisitedBB.test(SuccBB->getNumber()))
        continue;
      // We already visited SuccBB, thus MBB->SuccBB must be a backedge.
      // Check that the head matches what we have in the loop information.
      // Otherwise, we have an irreducible graph.
      if (!isProperBackedge(MLI, MBB, SuccBB))
        return true;
    }
  }
  return false;
}
Example #11
0
bool Thumb2SizeReduce::runOnMachineFunction(MachineFunction &MF) {
  const TargetMachine &TM = MF.getTarget();
  TII = static_cast<const Thumb2InstrInfo*>(TM.getInstrInfo());
  STI = &TM.getSubtarget<ARMSubtarget>();

  // Optimizing / minimizing size?
  AttributeSet FnAttrs = MF.getFunction()->getAttributes();
  OptimizeSize = FnAttrs.hasAttribute(AttributeSet::FunctionIndex,
                                      Attribute::OptimizeForSize);
  MinimizeSize = STI->isMinSize();

  BlockInfo.clear();
  BlockInfo.resize(MF.getNumBlockIDs());

  // Visit blocks in reverse post-order so LastCPSRDef is known for all
  // predecessors.
  ReversePostOrderTraversal<MachineFunction*> RPOT(&MF);
  bool Modified = false;
  for (ReversePostOrderTraversal<MachineFunction*>::rpo_iterator
       I = RPOT.begin(), E = RPOT.end(); I != E; ++I)
    Modified |= ReduceMBB(**I);
  return Modified;
}
Example #12
0
/// runOnMachineFunction - Loop over all of the basic blocks, inserting
/// vzeroupper instructions before function calls.
bool VZeroUpperInserter::runOnMachineFunction(MachineFunction &MF) {
  const X86Subtarget &ST = MF.getSubtarget<X86Subtarget>();
  if (!ST.hasAVX() || ST.hasAVX512() || ST.hasFastPartialYMMWrite())
    return false;
  TII = ST.getInstrInfo();
  MachineRegisterInfo &MRI = MF.getRegInfo();
  EverMadeChange = false;

  bool FnHasLiveInYmm = checkFnHasLiveInYmm(MRI);

  // Fast check: if the function doesn't use any ymm registers, we don't need
  // to insert any VZEROUPPER instructions.  This is constant-time, so it is
  // cheap in the common case of no ymm use.
  bool YMMUsed = FnHasLiveInYmm;
  if (!YMMUsed) {
    const TargetRegisterClass *RC = &X86::VR256RegClass;
    for (TargetRegisterClass::iterator i = RC->begin(), e = RC->end(); i != e;
         i++) {
      if (!MRI.reg_nodbg_empty(*i)) {
        YMMUsed = true;
        break;
      }
    }
  }
  if (!YMMUsed) {
    return false;
  }

  assert(BlockStates.empty() && DirtySuccessors.empty() &&
         "X86VZeroUpper state should be clear");
  BlockStates.resize(MF.getNumBlockIDs());

  // Process all blocks. This will compute block exit states, record the first
  // unguarded call in each block, and add successors of dirty blocks to the
  // DirtySuccessors list.
  for (MachineBasicBlock &MBB : MF)
    processBasicBlock(MBB);

  // If any YMM regs are live in to this function, add the entry block to the
  // DirtySuccessors list
  if (FnHasLiveInYmm)
    addDirtySuccessor(MF.front());

  // Re-visit all blocks that are successors of EXITS_DIRTY bsocks. Add
  // vzeroupper instructions to unguarded calls, and propagate EXITS_DIRTY
  // through PASS_THROUGH blocks.
  while (!DirtySuccessors.empty()) {
    MachineBasicBlock &MBB = *DirtySuccessors.back();
    DirtySuccessors.pop_back();
    BlockState &BBState = BlockStates[MBB.getNumber()];

    // MBB is a successor of a dirty block, so its first call needs to be
    // guarded.
    if (BBState.FirstUnguardedCall != MBB.end())
      insertVZeroUpper(BBState.FirstUnguardedCall, MBB);

    // If this successor was a pass-through block then it is now dirty, and its
    // successors need to be added to the worklist (if they haven't been
    // already).
    if (BBState.ExitState == PASS_THROUGH) {
      DEBUG(dbgs() << "MBB #" << MBB.getNumber()
                   << " was Pass-through, is now Dirty-out.\n");
      for (MachineBasicBlock::succ_iterator SI = MBB.succ_begin(),
                                            SE = MBB.succ_end();
           SI != SE; ++SI)
        addDirtySuccessor(**SI);
    }
  }

  BlockStates.clear();
  return EverMadeChange;
}
/// Insert LOOP and BLOCK markers at appropriate places.
static void PlaceMarkers(MachineFunction &MF, const MachineLoopInfo &MLI,
                         const WebAssemblyInstrInfo &TII,
                         MachineDominatorTree &MDT,
                         WebAssemblyFunctionInfo &MFI) {
  // For each block whose label represents the end of a scope, record the block
  // which holds the beginning of the scope. This will allow us to quickly skip
  // over scoped regions when walking blocks. We allocate one more than the
  // number of blocks in the function to accommodate for the possible fake block
  // we may insert at the end.
  SmallVector<MachineBasicBlock *, 8> ScopeTops(MF.getNumBlockIDs() + 1);

  // For eacn LOOP_END, the corresponding LOOP.
  DenseMap<const MachineInstr *, const MachineBasicBlock *> LoopTops;

  for (auto &MBB : MF) {
    // Place the LOOP for MBB if MBB is the header of a loop.
    PlaceLoopMarker(MBB, MF, ScopeTops, LoopTops, TII, MLI);

    // Place the BLOCK for MBB if MBB is branched to from above.
    PlaceBlockMarker(MBB, MF, ScopeTops, TII, MLI, MDT, MFI);
  }

  // Now rewrite references to basic blocks to be depth immediates.
  SmallVector<const MachineBasicBlock *, 8> Stack;
  for (auto &MBB : reverse(MF)) {
    for (auto &MI : reverse(MBB)) {
      switch (MI.getOpcode()) {
      case WebAssembly::BLOCK:
        assert(ScopeTops[Stack.back()->getNumber()] == &MBB &&
               "Block should be balanced");
        Stack.pop_back();
        break;
      case WebAssembly::LOOP:
        assert(Stack.back() == &MBB && "Loop top should be balanced");
        Stack.pop_back();
        Stack.pop_back();
        break;
      case WebAssembly::END_BLOCK:
        Stack.push_back(&MBB);
        break;
      case WebAssembly::END_LOOP:
        Stack.push_back(&MBB);
        Stack.push_back(LoopTops[&MI]);
        break;
      default:
        if (MI.isTerminator()) {
          // Rewrite MBB operands to be depth immediates.
          SmallVector<MachineOperand, 4> Ops(MI.operands());
          while (MI.getNumOperands() > 0)
            MI.RemoveOperand(MI.getNumOperands() - 1);
          for (auto MO : Ops) {
            if (MO.isMBB())
              MO = MachineOperand::CreateImm(GetDepth(Stack, MO.getMBB()));
            MI.addOperand(MF, MO);
          }
        }
        break;
      }
    }
  }
  assert(Stack.empty() && "Control flow should be balanced");
}
/// Sort the blocks, taking special care to make sure that loops are not
/// interrupted by blocks not dominated by their header.
/// TODO: There are many opportunities for improving the heuristics here.
/// Explore them.
static void SortBlocks(MachineFunction &MF, const MachineLoopInfo &MLI,
                       const MachineDominatorTree &MDT) {
  // Prepare for a topological sort: Record the number of predecessors each
  // block has, ignoring loop backedges.
  MF.RenumberBlocks();
  SmallVector<unsigned, 16> NumPredsLeft(MF.getNumBlockIDs(), 0);
  for (MachineBasicBlock &MBB : MF) {
    unsigned N = MBB.pred_size();
    if (MachineLoop *L = MLI.getLoopFor(&MBB))
      if (L->getHeader() == &MBB)
        for (const MachineBasicBlock *Pred : MBB.predecessors())
          if (L->contains(Pred))
            --N;
    NumPredsLeft[MBB.getNumber()] = N;
  }

  // Topological sort the CFG, with additional constraints:
  //  - Between a loop header and the last block in the loop, there can be
  //    no blocks not dominated by the loop header.
  //  - It's desirable to preserve the original block order when possible.
  // We use two ready lists; Preferred and Ready. Preferred has recently
  // processed sucessors, to help preserve block sequences from the original
  // order. Ready has the remaining ready blocks.
  PriorityQueue<MachineBasicBlock *, std::vector<MachineBasicBlock *>,
                CompareBlockNumbers>
      Preferred;
  PriorityQueue<MachineBasicBlock *, std::vector<MachineBasicBlock *>,
                CompareBlockNumbersBackwards>
      Ready;
  SmallVector<Entry, 4> Loops;
  for (MachineBasicBlock *MBB = &MF.front();;) {
    const MachineLoop *L = MLI.getLoopFor(MBB);
    if (L) {
      // If MBB is a loop header, add it to the active loop list. We can't put
      // any blocks that it doesn't dominate until we see the end of the loop.
      if (L->getHeader() == MBB)
        Loops.push_back(Entry(L));
      // For each active loop the block is in, decrement the count. If MBB is
      // the last block in an active loop, take it off the list and pick up any
      // blocks deferred because the header didn't dominate them.
      for (Entry &E : Loops)
        if (E.Loop->contains(MBB) && --E.NumBlocksLeft == 0)
          for (auto DeferredBlock : E.Deferred)
            Ready.push(DeferredBlock);
      while (!Loops.empty() && Loops.back().NumBlocksLeft == 0)
        Loops.pop_back();
    }
    // The main topological sort logic.
    for (MachineBasicBlock *Succ : MBB->successors()) {
      // Ignore backedges.
      if (MachineLoop *SuccL = MLI.getLoopFor(Succ))
        if (SuccL->getHeader() == Succ && SuccL->contains(MBB))
          continue;
      // Decrement the predecessor count. If it's now zero, it's ready.
      if (--NumPredsLeft[Succ->getNumber()] == 0)
        Preferred.push(Succ);
    }
    // Determine the block to follow MBB. First try to find a preferred block,
    // to preserve the original block order when possible.
    MachineBasicBlock *Next = nullptr;
    while (!Preferred.empty()) {
      Next = Preferred.top();
      Preferred.pop();
      // If X isn't dominated by the top active loop header, defer it until that
      // loop is done.
      if (!Loops.empty() &&
          !MDT.dominates(Loops.back().Loop->getHeader(), Next)) {
        Loops.back().Deferred.push_back(Next);
        Next = nullptr;
        continue;
      }
      // If Next was originally ordered before MBB, and it isn't because it was
      // loop-rotated above the header, it's not preferred.
      if (Next->getNumber() < MBB->getNumber() &&
          (!L || !L->contains(Next) ||
           L->getHeader()->getNumber() < Next->getNumber())) {
        Ready.push(Next);
        Next = nullptr;
        continue;
      }
      break;
    }
    // If we didn't find a suitable block in the Preferred list, check the
    // general Ready list.
    if (!Next) {
      // If there are no more blocks to process, we're done.
      if (Ready.empty()) {
        MaybeUpdateTerminator(MBB);
        break;
      }
      for (;;) {
        Next = Ready.top();
        Ready.pop();
        // If Next isn't dominated by the top active loop header, defer it until
        // that loop is done.
        if (!Loops.empty() &&
            !MDT.dominates(Loops.back().Loop->getHeader(), Next)) {
          Loops.back().Deferred.push_back(Next);
          continue;
        }
        break;
      }
    }
    // Move the next block into place and iterate.
    Next->moveAfter(MBB);
    MaybeUpdateTerminator(MBB);
    MBB = Next;
  }
  assert(Loops.empty() && "Active loop list not finished");
  MF.RenumberBlocks();

#ifndef NDEBUG
  SmallSetVector<MachineLoop *, 8> OnStack;

  // Insert a sentinel representing the degenerate loop that starts at the
  // function entry block and includes the entire function as a "loop" that
  // executes once.
  OnStack.insert(nullptr);

  for (auto &MBB : MF) {
    assert(MBB.getNumber() >= 0 && "Renumbered blocks should be non-negative.");

    MachineLoop *Loop = MLI.getLoopFor(&MBB);
    if (Loop && &MBB == Loop->getHeader()) {
      // Loop header. The loop predecessor should be sorted above, and the other
      // predecessors should be backedges below.
      for (auto Pred : MBB.predecessors())
        assert(
            (Pred->getNumber() < MBB.getNumber() || Loop->contains(Pred)) &&
            "Loop header predecessors must be loop predecessors or backedges");
      assert(OnStack.insert(Loop) && "Loops should be declared at most once.");
    } else {
      // Not a loop header. All predecessors should be sorted above.
      for (auto Pred : MBB.predecessors())
        assert(Pred->getNumber() < MBB.getNumber() &&
               "Non-loop-header predecessors should be topologically sorted");
      assert(OnStack.count(MLI.getLoopFor(&MBB)) &&
             "Blocks must be nested in their loops");
    }
    while (OnStack.size() > 1 && &MBB == LoopBottom(OnStack.back()))
      OnStack.pop_back();
  }
  assert(OnStack.pop_back_val() == nullptr &&
         "The function entry block shouldn't actually be a loop header");
  assert(OnStack.empty() &&
         "Control flow stack pushes and pops should be balanced.");
#endif
}
Example #15
0
bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
  TLI = MF.getTarget().getTargetLowering();
  TII = MF.getTarget().getInstrInfo();
  if (!TII) return false;

  DEBUG(dbgs() << "\nIfcvt: function (" << ++FnNum <<  ") \'"
               << MF.getFunction()->getName() << "\'");

  if (FnNum < IfCvtFnStart || (IfCvtFnStop != -1 && FnNum > IfCvtFnStop)) {
    DEBUG(dbgs() << " skipped\n");
    return false;
  }
  DEBUG(dbgs() << "\n");

  MF.RenumberBlocks();
  BBAnalysis.resize(MF.getNumBlockIDs());

  // Look for root nodes, i.e. blocks without successors.
  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
    if (I->succ_empty())
      Roots.push_back(I);

  std::vector<IfcvtToken*> Tokens;
  MadeChange = false;
  unsigned NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle +
    NumTriangleRev + NumTriangleFalse + NumTriangleFRev + NumDiamonds;
  while (IfCvtLimit == -1 || (int)NumIfCvts < IfCvtLimit) {
    // Do an initial analysis for each basic block and find all the potential
    // candidates to perform if-conversion.
    bool Change = AnalyzeBlocks(MF, Tokens);
    while (!Tokens.empty()) {
      IfcvtToken *Token = Tokens.back();
      Tokens.pop_back();
      BBInfo &BBI = Token->BBI;
      IfcvtKind Kind = Token->Kind;
      unsigned NumDups = Token->NumDups;
      unsigned NumDups2 = Token->NumDups2;

      delete Token;

      // If the block has been evicted out of the queue or it has already been
      // marked dead (due to it being predicated), then skip it.
      if (BBI.IsDone)
        BBI.IsEnqueued = false;
      if (!BBI.IsEnqueued)
        continue;

      BBI.IsEnqueued = false;

      bool RetVal = false;
      switch (Kind) {
      default: assert(false && "Unexpected!");
        break;
      case ICSimple:
      case ICSimpleFalse: {
        bool isFalse = Kind == ICSimpleFalse;
        if ((isFalse && DisableSimpleF) || (!isFalse && DisableSimple)) break;
        DEBUG(dbgs() << "Ifcvt (Simple" << (Kind == ICSimpleFalse ? " false" :"")
                     << "): BB#" << BBI.BB->getNumber() << " ("
                     << ((Kind == ICSimpleFalse)
                         ? BBI.FalseBB->getNumber()
                         : BBI.TrueBB->getNumber()) << ") ");
        RetVal = IfConvertSimple(BBI, Kind);
        DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
        if (RetVal) {
          if (isFalse) NumSimpleFalse++;
          else         NumSimple++;
        }
       break;
      }
      case ICTriangle:
      case ICTriangleRev:
      case ICTriangleFalse:
      case ICTriangleFRev: {
        bool isFalse = Kind == ICTriangleFalse;
        bool isRev   = (Kind == ICTriangleRev || Kind == ICTriangleFRev);
        if (DisableTriangle && !isFalse && !isRev) break;
        if (DisableTriangleR && !isFalse && isRev) break;
        if (DisableTriangleF && isFalse && !isRev) break;
        if (DisableTriangleFR && isFalse && isRev) break;
        DEBUG(dbgs() << "Ifcvt (Triangle");
        if (isFalse)
          DEBUG(dbgs() << " false");
        if (isRev)
          DEBUG(dbgs() << " rev");
        DEBUG(dbgs() << "): BB#" << BBI.BB->getNumber() << " (T:"
                     << BBI.TrueBB->getNumber() << ",F:"
                     << BBI.FalseBB->getNumber() << ") ");
        RetVal = IfConvertTriangle(BBI, Kind);
        DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
        if (RetVal) {
          if (isFalse) {
            if (isRev) NumTriangleFRev++;
            else       NumTriangleFalse++;
          } else {
            if (isRev) NumTriangleRev++;
            else       NumTriangle++;
          }
        }
        break;
      }
      case ICDiamond: {
        if (DisableDiamond) break;
        DEBUG(dbgs() << "Ifcvt (Diamond): BB#" << BBI.BB->getNumber() << " (T:"
                     << BBI.TrueBB->getNumber() << ",F:"
                     << BBI.FalseBB->getNumber() << ") ");
        RetVal = IfConvertDiamond(BBI, Kind, NumDups, NumDups2);
        DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
        if (RetVal) NumDiamonds++;
        break;
      }
      }

      Change |= RetVal;

      NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle + NumTriangleRev +
        NumTriangleFalse + NumTriangleFRev + NumDiamonds;
      if (IfCvtLimit != -1 && (int)NumIfCvts >= IfCvtLimit)
        break;
    }

    if (!Change)
      break;
    MadeChange |= Change;
  }

  // Delete tokens in case of early exit.
  while (!Tokens.empty()) {
    IfcvtToken *Token = Tokens.back();
    Tokens.pop_back();
    delete Token;
  }

  Tokens.clear();
  Roots.clear();
  BBAnalysis.clear();

  if (MadeChange) {
    BranchFolder BF(false);
    BF.OptimizeFunction(MF, TII,
                        MF.getTarget().getRegisterInfo(),
                        getAnalysisIfAvailable<MachineModuleInfo>());
  }

  return MadeChange;
}
Example #16
0
bool MSP430BSel::runOnMachineFunction(MachineFunction &Fn) {
  const MSP430InstrInfo *TII =
             static_cast<const MSP430InstrInfo*>(Fn.getTarget().getInstrInfo());
  // Give the blocks of the function a dense, in-order, numbering.
  Fn.RenumberBlocks();
  BlockSizes.resize(Fn.getNumBlockIDs());

  // Measure each MBB and compute a size for the entire function.
  unsigned FuncSize = 0;
  for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
       ++MFI) {
    MachineBasicBlock *MBB = MFI;

    unsigned BlockSize = 0;
    for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end();
         MBBI != EE; ++MBBI)
      BlockSize += TII->GetInstSizeInBytes(MBBI);

    BlockSizes[MBB->getNumber()] = BlockSize;
    FuncSize += BlockSize;
  }

  // If the entire function is smaller than the displacement of a branch field,
  // we know we don't need to shrink any branches in this function.  This is a
  // common case.
  if (FuncSize < (1 << 9)) {
    BlockSizes.clear();
    return false;
  }

  // For each conditional branch, if the offset to its destination is larger
  // than the offset field allows, transform it into a long branch sequence
  // like this:
  //   short branch:
  //     bCC MBB
  //   long branch:
  //     b!CC $PC+6
  //     b MBB
  //
  bool MadeChange = true;
  bool EverMadeChange = false;
  while (MadeChange) {
    // Iteratively expand branches until we reach a fixed point.
    MadeChange = false;

    for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
         ++MFI) {
      MachineBasicBlock &MBB = *MFI;
      unsigned MBBStartOffset = 0;
      for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
           I != E; ++I) {
        if ((I->getOpcode() != MSP430::JCC || I->getOperand(0).isImm()) &&
            I->getOpcode() != MSP430::JMP) {
          MBBStartOffset += TII->GetInstSizeInBytes(I);
          continue;
        }

        // Determine the offset from the current branch to the destination
        // block.
        MachineBasicBlock *Dest = I->getOperand(0).getMBB();

        int BranchSize;
        if (Dest->getNumber() <= MBB.getNumber()) {
          // If this is a backwards branch, the delta is the offset from the
          // start of this block to this branch, plus the sizes of all blocks
          // from this block to the dest.
          BranchSize = MBBStartOffset;

          for (unsigned i = Dest->getNumber(), e = MBB.getNumber(); i != e; ++i)
            BranchSize += BlockSizes[i];
        } else {
          // Otherwise, add the size of the blocks between this block and the
          // dest to the number of bytes left in this block.
          BranchSize = -MBBStartOffset;

          for (unsigned i = MBB.getNumber(), e = Dest->getNumber(); i != e; ++i)
            BranchSize += BlockSizes[i];
        }

        // If this branch is in range, ignore it.
        if (isInt<10>(BranchSize)) {
          MBBStartOffset += 2;
          continue;
        }

        // Otherwise, we have to expand it to a long branch.
        unsigned NewSize;
        MachineInstr *OldBranch = I;
        DebugLoc dl = OldBranch->getDebugLoc();

        if (I->getOpcode() == MSP430::JMP) {
          NewSize = 4;
        } else {
          // The BCC operands are:
          // 0. MSP430 branch predicate
          // 1. Target MBB
          SmallVector<MachineOperand, 1> Cond;
          Cond.push_back(I->getOperand(1));

          // Jump over the uncond branch inst (i.e. $+6) on opposite condition.
          TII->ReverseBranchCondition(Cond);
          BuildMI(MBB, I, dl, TII->get(MSP430::JCC))
            .addImm(4).addOperand(Cond[0]);

          NewSize = 6;
        }
        // Uncond branch to the real destination.
        I = BuildMI(MBB, I, dl, TII->get(MSP430::Bi)).addMBB(Dest);

        // Remove the old branch from the function.
        OldBranch->eraseFromParent();

        // Remember that this instruction is NewSize bytes, increase the size of the
        // block by NewSize-2, remember to iterate.
        BlockSizes[MBB.getNumber()] += NewSize-2;
        MBBStartOffset += NewSize;

        ++NumExpanded;
        MadeChange = true;
      }
    }
    EverMadeChange |= MadeChange;
  }

  BlockSizes.clear();
  return true;
}
bool PPCBSel::runOnMachineFunction(MachineFunction &Fn) {
  const TargetInstrInfo *TII = Fn.getTarget().getInstrInfo();
  // Give the blocks of the function a dense, in-order, numbering.
  Fn.RenumberBlocks();
  BlockSizes.resize(Fn.getNumBlockIDs());

  // Measure each MBB and compute a size for the entire function.
  unsigned FuncSize = 0;
  for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
       ++MFI) {
    MachineBasicBlock *MBB = MFI;

    unsigned BlockSize = 0;
    for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end();
         MBBI != EE; ++MBBI)
      BlockSize += TII->GetInstSizeInBytes(MBBI);
    
    BlockSizes[MBB->getNumber()] = BlockSize;
    FuncSize += BlockSize;
  }
  
  // If the entire function is smaller than the displacement of a branch field,
  // we know we don't need to shrink any branches in this function.  This is a
  // common case.
  if (FuncSize < (1 << 15)) {
    BlockSizes.clear();
    return false;
  }
  
  // For each conditional branch, if the offset to its destination is larger
  // than the offset field allows, transform it into a long branch sequence
  // like this:
  //   short branch:
  //     bCC MBB
  //   long branch:
  //     b!CC $PC+8
  //     b MBB
  //
  bool MadeChange = true;
  bool EverMadeChange = false;
  while (MadeChange) {
    // Iteratively expand branches until we reach a fixed point.
    MadeChange = false;
  
    for (MachineFunction::iterator MFI = Fn.begin(), E = Fn.end(); MFI != E;
         ++MFI) {
      MachineBasicBlock &MBB = *MFI;
      unsigned MBBStartOffset = 0;
      for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
           I != E; ++I) {
        if (I->getOpcode() != PPC::BCC || I->getOperand(2).isImmediate()) {
          MBBStartOffset += TII->GetInstSizeInBytes(I);
          continue;
        }
        
        // Determine the offset from the current branch to the destination
        // block.
        MachineBasicBlock *Dest = I->getOperand(2).getMBB();
        
        int BranchSize;
        if (Dest->getNumber() <= MBB.getNumber()) {
          // If this is a backwards branch, the delta is the offset from the
          // start of this block to this branch, plus the sizes of all blocks
          // from this block to the dest.
          BranchSize = MBBStartOffset;
          
          for (unsigned i = Dest->getNumber(), e = MBB.getNumber(); i != e; ++i)
            BranchSize += BlockSizes[i];
        } else {
          // Otherwise, add the size of the blocks between this block and the
          // dest to the number of bytes left in this block.
          BranchSize = -MBBStartOffset;

          for (unsigned i = MBB.getNumber(), e = Dest->getNumber(); i != e; ++i)
            BranchSize += BlockSizes[i];
        }

        // If this branch is in range, ignore it.
        if (isInt16(BranchSize)) {
          MBBStartOffset += 4;
          continue;
        }
        
        // Otherwise, we have to expand it to a long branch.
        // The BCC operands are:
        // 0. PPC branch predicate
        // 1. CR register
        // 2. Target MBB
        PPC::Predicate Pred = (PPC::Predicate)I->getOperand(0).getImm();
        unsigned CRReg = I->getOperand(1).getReg();
        
        MachineInstr *OldBranch = I;
        
        // Jump over the uncond branch inst (i.e. $PC+8) on opposite condition.
        BuildMI(MBB, I, TII->get(PPC::BCC))
          .addImm(PPC::InvertPredicate(Pred)).addReg(CRReg).addImm(2);
        
        // Uncond branch to the real destination.
        I = BuildMI(MBB, I, TII->get(PPC::B)).addMBB(Dest);

        // Remove the old branch from the function.
        OldBranch->eraseFromParent();
        
        // Remember that this instruction is 8-bytes, increase the size of the
        // block by 4, remember to iterate.
        BlockSizes[MBB.getNumber()] += 4;
        MBBStartOffset += 8;
        ++NumExpanded;
        MadeChange = true;
      }
    }
    EverMadeChange |= MadeChange;
  }
  
  BlockSizes.clear();
  return true;
}