Ejemplo n.º 1
0
void RegionGenerator::addOperandToPHI(ScopStmt &Stmt, const PHINode *PHI,
                                      PHINode *PHICopy, BasicBlock *IncomingBB,
                                      ValueMapT &GlobalMap,
                                      LoopToScevMapT &LTS) {
  Region *StmtR = Stmt.getRegion();

  // If the incoming block was not yet copied mark this PHI as incomplete.
  // Once the block will be copied the incoming value will be added.
  BasicBlock *BBCopy = BlockMap[IncomingBB];
  if (!BBCopy) {
    assert(StmtR->contains(IncomingBB) &&
           "Bad incoming block for PHI in non-affine region");
    IncompletePHINodeMap[IncomingBB].push_back(std::make_pair(PHI, PHICopy));
    return;
  }

  Value *OpCopy = nullptr;
  if (StmtR->contains(IncomingBB)) {
    assert(RegionMaps.count(BBCopy) &&
           "Incoming PHI block did not have a BBMap");
    ValueMapT &BBCopyMap = RegionMaps[BBCopy];

    Value *Op = PHI->getIncomingValueForBlock(IncomingBB);
    OpCopy =
        getNewValue(Stmt, Op, BBCopyMap, GlobalMap, LTS, getLoopForInst(PHI));
  } else {

    if (PHICopy->getBasicBlockIndex(BBCopy) >= 0)
      return;

    AllocaInst *PHIOpAddr =
        getOrCreateAlloca(const_cast<PHINode *>(PHI), PHIOpMap, ".phiops");
    OpCopy = new LoadInst(PHIOpAddr, PHIOpAddr->getName() + ".reload",
                          BlockMap[IncomingBB]->getTerminator());
  }

  assert(OpCopy && "Incoming PHI value was not copied properly");
  assert(BBCopy && "Incoming PHI block was not copied properly");
  PHICopy->addIncoming(OpCopy, BBCopy);
}
Ejemplo n.º 2
0
void BlockGenerator::copyInstruction(ScopStmt &Stmt, const Instruction *Inst,
                                     ValueMapT &BBMap, ValueMapT &GlobalMap,
                                     LoopToScevMapT &LTS) {

  // First check for possible scalar dependences for this instruction.
  generateScalarLoads(Stmt, Inst, BBMap);

  // Terminator instructions control the control flow. They are explicitly
  // expressed in the clast and do not need to be copied.
  if (Inst->isTerminator())
    return;

  Loop *L = getLoopForInst(Inst);
  if ((Stmt.isBlockStmt() || !Stmt.getRegion()->contains(L)) &&
      canSynthesize(Inst, &LI, &SE, &Stmt.getParent()->getRegion())) {
    Value *NewValue = getNewValue(Stmt, Inst, BBMap, GlobalMap, LTS, L);
    BBMap[Inst] = NewValue;
    return;
  }

  if (const LoadInst *Load = dyn_cast<LoadInst>(Inst)) {
    Value *NewLoad = generateScalarLoad(Stmt, Load, BBMap, GlobalMap, LTS);
    // Compute NewLoad before its insertion in BBMap to make the insertion
    // deterministic.
    BBMap[Load] = NewLoad;
    return;
  }

  if (const StoreInst *Store = dyn_cast<StoreInst>(Inst)) {
    Value *NewStore = generateScalarStore(Stmt, Store, BBMap, GlobalMap, LTS);
    // Compute NewStore before its insertion in BBMap to make the insertion
    // deterministic.
    BBMap[Store] = NewStore;
    return;
  }

  if (const PHINode *PHI = dyn_cast<PHINode>(Inst)) {
    copyPHIInstruction(Stmt, PHI, BBMap, GlobalMap, LTS);
    return;
  }

  // Skip some special intrinsics for which we do not adjust the semantics to
  // the new schedule. All others are handled like every other instruction.
  if (auto *IT = dyn_cast<IntrinsicInst>(Inst)) {
    switch (IT->getIntrinsicID()) {
    // Lifetime markers are ignored.
    case llvm::Intrinsic::lifetime_start:
    case llvm::Intrinsic::lifetime_end:
    // Invariant markers are ignored.
    case llvm::Intrinsic::invariant_start:
    case llvm::Intrinsic::invariant_end:
    // Some misc annotations are ignored.
    case llvm::Intrinsic::var_annotation:
    case llvm::Intrinsic::ptr_annotation:
    case llvm::Intrinsic::annotation:
    case llvm::Intrinsic::donothing:
    case llvm::Intrinsic::assume:
    case llvm::Intrinsic::expect:
      return;
    default:
      // Other intrinsics are copied.
      break;
    }
  }

  copyInstScalar(Stmt, Inst, BBMap, GlobalMap, LTS);
}
Ejemplo n.º 3
0
void RegionGenerator::generateScalarStores(ScopStmt &Stmt, BasicBlock *BB,
                                           ValueMapT &BBMap,
                                           ValueMapT &GlobalMap) {
  const Region &R = Stmt.getParent()->getRegion();

  Region *StmtR = Stmt.getRegion();
  assert(StmtR && "Block statements need to use the generateScalarStores() "
                  "function in the BlockGenerator");

  BasicBlock *ExitBB = StmtR->getExit();

  // For region statements three kinds of scalar stores exists:
  //  (1) A definition used by a non-phi instruction outside the region.
  //  (2) A phi-instruction in the region entry.
  //  (3) A write to a phi instruction in the region exit.
  // The last case is the tricky one since we do not know anymore which
  // predecessor of the exit needs to store the operand value that doesn't
  // have a definition in the region. Therefore, we have to check in each
  // block in the region if we should store the value or not.

  // Iterate over all accesses in the given statement.
  for (MemoryAccess *MA : Stmt) {

    // Skip non-scalar and read accesses.
    if (!MA->isScalar() || MA->isRead())
      continue;

    Instruction *ScalarBase = cast<Instruction>(MA->getBaseAddr());
    Instruction *ScalarInst = MA->getAccessInstruction();
    PHINode *ScalarBasePHI = dyn_cast<PHINode>(ScalarBase);

    Value *ScalarValue = nullptr;
    AllocaInst *ScalarAddr = nullptr;

    if (!ScalarBasePHI) {
      // Case (1)
      ScalarAddr = getOrCreateAlloca(ScalarBase, ScalarMap, ".s2a");
      ScalarValue = ScalarInst;
    } else if (ScalarBasePHI->getParent() != ExitBB) {
      // Case (2)
      assert(ScalarBasePHI->getParent() == StmtR->getEntry() &&
             "Bad PHI self write in non-affine region");
      assert(ScalarBase == ScalarInst &&
             "Bad PHI self write in non-affine region");
      ScalarAddr = getOrCreateAlloca(ScalarBase, ScalarMap, ".s2a");
      ScalarValue = ScalarInst;
    } else {
      int PHIIdx = ScalarBasePHI->getBasicBlockIndex(BB);
      // Skip accesses we will not handle in this basic block but in another one
      // in the statement region.
      if (PHIIdx < 0)
        continue;

      // Case (3)
      ScalarAddr = getOrCreateAlloca(ScalarBase, PHIOpMap, ".phiops");
      ScalarValue = ScalarBasePHI->getIncomingValue(PHIIdx);
    }

    ScalarValue =
        getNewScalarValue(ScalarValue, R, ScalarMap, BBMap, GlobalMap);
    Builder.CreateStore(ScalarValue, ScalarAddr);
  }
}
Ejemplo n.º 4
0
void RegionGenerator::copyStmt(ScopStmt &Stmt, ValueMapT &GlobalMap,
                               LoopToScevMapT &LTS) {
  assert(Stmt.isRegionStmt() &&
         "Only region statements can be copied by the block generator");

  // Forget all old mappings.
  BlockMap.clear();
  RegionMaps.clear();
  IncompletePHINodeMap.clear();

  // The region represented by the statement.
  Region *R = Stmt.getRegion();

  // Create a dedicated entry for the region where we can reload all demoted
  // inputs.
  BasicBlock *EntryBB = R->getEntry();
  BasicBlock *EntryBBCopy =
      SplitBlock(Builder.GetInsertBlock(), Builder.GetInsertPoint(), &DT, &LI);
  EntryBBCopy->setName("polly.stmt." + EntryBB->getName() + ".entry");
  Builder.SetInsertPoint(EntryBBCopy->begin());

  for (auto PI = pred_begin(EntryBB), PE = pred_end(EntryBB); PI != PE; ++PI)
    if (!R->contains(*PI))
      BlockMap[*PI] = EntryBBCopy;

  // Iterate over all blocks in the region in a breadth-first search.
  std::deque<BasicBlock *> Blocks;
  SmallPtrSet<BasicBlock *, 8> SeenBlocks;
  Blocks.push_back(EntryBB);
  SeenBlocks.insert(EntryBB);

  while (!Blocks.empty()) {
    BasicBlock *BB = Blocks.front();
    Blocks.pop_front();

    // First split the block and update dominance information.
    BasicBlock *BBCopy = splitBB(BB);
    BasicBlock *BBCopyIDom = repairDominance(BB, BBCopy);

    // In order to remap PHI nodes we store also basic block mappings.
    BlockMap[BB] = BBCopy;

    // Get the mapping for this block and initialize it with the mapping
    // available at its immediate dominator (in the new region).
    ValueMapT &RegionMap = RegionMaps[BBCopy];
    RegionMap = RegionMaps[BBCopyIDom];

    // Copy the block with the BlockGenerator.
    copyBB(Stmt, BB, BBCopy, RegionMap, GlobalMap, LTS);

    // In order to remap PHI nodes we store also basic block mappings.
    BlockMap[BB] = BBCopy;

    // Add values to incomplete PHI nodes waiting for this block to be copied.
    for (const PHINodePairTy &PHINodePair : IncompletePHINodeMap[BB])
      addOperandToPHI(Stmt, PHINodePair.first, PHINodePair.second, BB,
                      GlobalMap, LTS);
    IncompletePHINodeMap[BB].clear();

    // And continue with new successors inside the region.
    for (auto SI = succ_begin(BB), SE = succ_end(BB); SI != SE; SI++)
      if (R->contains(*SI) && SeenBlocks.insert(*SI).second)
        Blocks.push_back(*SI);
  }

  // Now create a new dedicated region exit block and add it to the region map.
  BasicBlock *ExitBBCopy =
      SplitBlock(Builder.GetInsertBlock(), Builder.GetInsertPoint(), &DT, &LI);
  ExitBBCopy->setName("polly.stmt." + R->getExit()->getName() + ".exit");
  BlockMap[R->getExit()] = ExitBBCopy;

  repairDominance(R->getExit(), ExitBBCopy);

  // As the block generator doesn't handle control flow we need to add the
  // region control flow by hand after all blocks have been copied.
  for (BasicBlock *BB : SeenBlocks) {

    BranchInst *BI = cast<BranchInst>(BB->getTerminator());

    BasicBlock *BBCopy = BlockMap[BB];
    Instruction *BICopy = BBCopy->getTerminator();

    ValueMapT &RegionMap = RegionMaps[BBCopy];
    RegionMap.insert(BlockMap.begin(), BlockMap.end());

    Builder.SetInsertPoint(BBCopy);
    copyInstScalar(Stmt, BI, RegionMap, GlobalMap, LTS);
    BICopy->eraseFromParent();
  }

  // Add counting PHI nodes to all loops in the region that can be used as
  // replacement for SCEVs refering to the old loop.
  for (BasicBlock *BB : SeenBlocks) {
    Loop *L = LI.getLoopFor(BB);
    if (L == nullptr || L->getHeader() != BB)
      continue;

    BasicBlock *BBCopy = BlockMap[BB];
    Value *NullVal = Builder.getInt32(0);
    PHINode *LoopPHI =
        PHINode::Create(Builder.getInt32Ty(), 2, "polly.subregion.iv");
    Instruction *LoopPHIInc = BinaryOperator::CreateAdd(
        LoopPHI, Builder.getInt32(1), "polly.subregion.iv.inc");
    LoopPHI->insertBefore(BBCopy->begin());
    LoopPHIInc->insertBefore(BBCopy->getTerminator());

    for (auto *PredBB : make_range(pred_begin(BB), pred_end(BB))) {
      if (!R->contains(PredBB))
        continue;
      if (L->contains(PredBB))
        LoopPHI->addIncoming(LoopPHIInc, BlockMap[PredBB]);
      else
        LoopPHI->addIncoming(NullVal, BlockMap[PredBB]);
    }

    for (auto *PredBBCopy : make_range(pred_begin(BBCopy), pred_end(BBCopy)))
      if (LoopPHI->getBasicBlockIndex(PredBBCopy) < 0)
        LoopPHI->addIncoming(NullVal, PredBBCopy);

    LTS[L] = SE.getUnknown(LoopPHI);
  }

  // Add all mappings from the region to the global map so outside uses will use
  // the copied instructions.
  for (auto &BBMap : RegionMaps)
    GlobalMap.insert(BBMap.second.begin(), BBMap.second.end());

  // Reset the old insert point for the build.
  Builder.SetInsertPoint(ExitBBCopy->begin());
}