C++ SmallPtrSetImpl类代码示例

/// Collect all blocks from \p CurLoop which lie on all possible paths from
/// the header of \p CurLoop (inclusive) to BB (exclusive) into the set
/// \p Predecessors. If \p BB is the header, \p Predecessors will be empty.
static void collectTransitivePredecessors(
    const Loop *CurLoop, const BasicBlock *BB,
    SmallPtrSetImpl<const BasicBlock *> &Predecessors) {
  assert(Predecessors.empty() && "Garbage in predecessors set?");
  assert(CurLoop->contains(BB) && "Should only be called for loop blocks!");
  if (BB == CurLoop->getHeader())
    return;
  SmallVector<const BasicBlock *, 4> WorkList;
  for (auto *Pred : predecessors(BB)) {
    Predecessors.insert(Pred);
    WorkList.push_back(Pred);
  }
  while (!WorkList.empty()) {
    auto *Pred = WorkList.pop_back_val();
    assert(CurLoop->contains(Pred) && "Should only reach loop blocks!");
    // We are not interested in backedges and we don't want to leave loop.
    if (Pred == CurLoop->getHeader())
      continue;
    // TODO: If BB lies in an inner loop of CurLoop, this will traverse over all
    // blocks of this inner loop, even those that are always executed AFTER the
    // BB. It may make our analysis more conservative than it could be, see test
    // @nested and @nested_no_throw in test/Analysis/MustExecute/loop-header.ll.
    // We can ignore backedge of all loops containing BB to get a sligtly more
    // optimistic result.
    for (auto *PredPred : predecessors(Pred))
      if (Predecessors.insert(PredPred).second)
        WorkList.push_back(PredPred);
  }
}

bool RecurrenceDescriptor::getSourceExtensionKind(
    Instruction *Start, Instruction *Exit, Type *RT, bool &IsSigned,
    SmallPtrSetImpl<Instruction *> &Visited,
    SmallPtrSetImpl<Instruction *> &CI) {

  SmallVector<Instruction *, 8> Worklist;
  bool FoundOneOperand = false;
  unsigned DstSize = RT->getPrimitiveSizeInBits();
  Worklist.push_back(Exit);

  // Traverse the instructions in the reduction expression, beginning with the
  // exit value.
  while (!Worklist.empty()) {
    Instruction *I = Worklist.pop_back_val();
    for (Use &U : I->operands()) {

      // Terminate the traversal if the operand is not an instruction, or we
      // reach the starting value.
      Instruction *J = dyn_cast<Instruction>(U.get());
      if (!J || J == Start)
        continue;

      // Otherwise, investigate the operation if it is also in the expression.
      if (Visited.count(J)) {
        Worklist.push_back(J);
        continue;
      }

      // If the operand is not in Visited, it is not a reduction operation, but
      // it does feed into one. Make sure it is either a single-use sign- or
      // zero-extend instruction.
      CastInst *Cast = dyn_cast<CastInst>(J);
      bool IsSExtInst = isa<SExtInst>(J);
      if (!Cast || !Cast->hasOneUse() || !(isa<ZExtInst>(J) || IsSExtInst))
        return false;

      // Ensure the source type of the extend is no larger than the reduction
      // type. It is not necessary for the types to be identical.
      unsigned SrcSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
      if (SrcSize > DstSize)
        return false;

      // Furthermore, ensure that all such extends are of the same kind.
      if (FoundOneOperand) {
        if (IsSigned != IsSExtInst)
          return false;
      } else {
        FoundOneOperand = true;
        IsSigned = IsSExtInst;
      }

      // Lastly, if the source type of the extend matches the reduction type,
      // add the extend to CI so that we can avoid accounting for it in the
      // cost model.
      if (SrcSize == DstSize)
        CI.insert(Cast);
    }
  }
  return true;
}

void LTOCodeGenerator::
applyRestriction(GlobalValue &GV,
                 ArrayRef<StringRef> Libcalls,
                 std::vector<const char*> &MustPreserveList,
                 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
                 Mangler &Mangler) {
  // There are no restrictions to apply to declarations.
  if (GV.isDeclaration())
    return;

  // There is nothing more restrictive than private linkage.
  if (GV.hasPrivateLinkage())
    return;

  SmallString<64> Buffer;
  TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);

  if (MustPreserveSymbols.count(Buffer))
    MustPreserveList.push_back(GV.getName().data());
  if (AsmUndefinedRefs.count(Buffer))
    AsmUsed.insert(&GV);

  // Conservatively append user-supplied runtime library functions to
  // llvm.compiler.used.  These could be internalized and deleted by
  // optimizations like -globalopt, causing problems when later optimizations
  // add new library calls (e.g., llvm.memset => memset and printf => puts).
  // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
  if (isa<Function>(GV) &&
      std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
    AsmUsed.insert(&GV);
}

/// MarkBlocksLiveIn - Insert BB and all of its predecessors into LiveBBs until
/// we reach blocks we've already seen.
static void MarkBlocksLiveIn(BasicBlock *BB,
                             SmallPtrSetImpl<BasicBlock *> &LiveBBs) {
  if (!LiveBBs.insert(BB).second)
    return; // already been here.

  df_iterator_default_set<BasicBlock*> Visited;

  for (BasicBlock *B : inverse_depth_first_ext(BB, Visited))
    LiveBBs.insert(B);

}

/// Find values that are marked as llvm.used.
static void findUsedValues(GlobalVariable *LLVMUsed,
                           SmallPtrSetImpl<const GlobalValue*> &UsedValues) {
    if (!LLVMUsed) return;
    UsedValues.insert(LLVMUsed);

    ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());

    for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
        if (GlobalValue *GV =
                    dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
            UsedValues.insert(GV);
}

// Breadth-first walk of the use-def graph; determine the set of nodes
// we care about and eagerly determine if some of them are poisonous.
void Float2IntPass::walkBackwards(const SmallPtrSetImpl<Instruction*> &Roots) {
  std::deque<Instruction*> Worklist(Roots.begin(), Roots.end());
  while (!Worklist.empty()) {
    Instruction *I = Worklist.back();
    Worklist.pop_back();

    if (SeenInsts.find(I) != SeenInsts.end())
      // Seen already.
      continue;

    switch (I->getOpcode()) {
      // FIXME: Handle select and phi nodes.
    default:
      // Path terminated uncleanly.
      seen(I, badRange());
      break;

    case Instruction::UIToFP:
    case Instruction::SIToFP: {
      // Path terminated cleanly - use the type of the integer input to seed
      // the analysis.
      unsigned BW = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
      auto Input = ConstantRange(BW, true);
      auto CastOp = (Instruction::CastOps)I->getOpcode();
      seen(I, validateRange(Input.castOp(CastOp, MaxIntegerBW+1)));
      continue;
    }

    case Instruction::FAdd:
    case Instruction::FSub:
    case Instruction::FMul:
    case Instruction::FPToUI:
    case Instruction::FPToSI:
    case Instruction::FCmp:
      seen(I, unknownRange());
      break;
    }

    for (Value *O : I->operands()) {
      if (Instruction *OI = dyn_cast<Instruction>(O)) {
        // Unify def-use chains if they interfere.
        ECs.unionSets(I, OI);
        if (SeenInsts.find(I)->second != badRange())
          Worklist.push_back(OI);
      } else if (!isa<ConstantFP>(O)) {
        // Not an instruction or ConstantFP? we can't do anything.
        seen(I, badRange());
      }
    }
  }
}

/// Merge an autorelease with a retain into a fused call.
bool ObjCARCContract::contractAutorelease(
    Function &F, Instruction *Autorelease, ARCInstKind Class,
    SmallPtrSetImpl<Instruction *> &DependingInstructions,
    SmallPtrSetImpl<const BasicBlock *> &Visited) {
  const Value *Arg = GetArgRCIdentityRoot(Autorelease);

  // Check that there are no instructions between the retain and the autorelease
  // (such as an autorelease_pop) which may change the count.
  CallInst *Retain = nullptr;
  if (Class == ARCInstKind::AutoreleaseRV)
    FindDependencies(RetainAutoreleaseRVDep, Arg,
                     Autorelease->getParent(), Autorelease,
                     DependingInstructions, Visited, PA);
  else
    FindDependencies(RetainAutoreleaseDep, Arg,
                     Autorelease->getParent(), Autorelease,
                     DependingInstructions, Visited, PA);

  Visited.clear();
  if (DependingInstructions.size() != 1) {
    DependingInstructions.clear();
    return false;
  }

  Retain = dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
  DependingInstructions.clear();

  if (!Retain || GetBasicARCInstKind(Retain) != ARCInstKind::Retain ||
      GetArgRCIdentityRoot(Retain) != Arg)
    return false;

  Changed = true;
  ++NumPeeps;

  LLVM_DEBUG(dbgs() << "    Fusing retain/autorelease!\n"
                       "        Autorelease:"
                    << *Autorelease
                    << "\n"
                       "        Retain: "
                    << *Retain << "\n");

  Function *Decl = EP.get(Class == ARCInstKind::AutoreleaseRV
                              ? ARCRuntimeEntryPointKind::RetainAutoreleaseRV
                              : ARCRuntimeEntryPointKind::RetainAutorelease);
  Retain->setCalledFunction(Decl);

  LLVM_DEBUG(dbgs() << "        New RetainAutorelease: " << *Retain << "\n");

  EraseInstruction(Autorelease);
  return true;
}

static bool isSafeToMove(Instruction *Inst, AliasAnalysis *AA,
                         SmallPtrSetImpl<Instruction *> &Stores) {

  if (Inst->mayWriteToMemory()) {
    Stores.insert(Inst);
    return false;
  }

  if (LoadInst *L = dyn_cast<LoadInst>(Inst)) {
    MemoryLocation Loc = MemoryLocation::get(L);
    for (Instruction *S : Stores)
      if (AA->getModRefInfo(S, Loc) & MRI_Mod)
        return false;
  }

  if (isa<TerminatorInst>(Inst) || isa<PHINode>(Inst))
    return false;

  // Convergent operations cannot be made control-dependent on additional
  // values.
  if (auto CS = CallSite(Inst)) {
    if (CS.hasFnAttr(Attribute::Convergent))
      return false;
  }

  return true;
}

bool RecurrenceDescriptor::areAllUsesIn(Instruction *I,
                                        SmallPtrSetImpl<Instruction *> &Set) {
  for (User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use)
    if (!Set.count(dyn_cast<Instruction>(*Use)))
      return false;
  return true;
}

static void collectMDInDomain(const MDNode *List, const MDNode *Domain,
                              SmallPtrSetImpl<const MDNode *> &Nodes) {
  for (const MDOperand &MDOp : List->operands())
    if (const MDNode *MD = dyn_cast<MDNode>(MDOp))
      if (AliasScopeNode(MD).getDomain() == Domain)
        Nodes.insert(MD);
}

void AMDGPUAlwaysInline::recursivelyVisitUsers(
  GlobalValue &GV,
  SmallPtrSetImpl<Function *> &FuncsToAlwaysInline) {
  SmallVector<User *, 16> Stack;

  SmallPtrSet<const Value *, 8> Visited;

  for (User *U : GV.users())
    Stack.push_back(U);

  while (!Stack.empty()) {
    User *U = Stack.pop_back_val();
    if (!Visited.insert(U).second)
      continue;

    if (Instruction *I = dyn_cast<Instruction>(U)) {
      Function *F = I->getParent()->getParent();
      if (!AMDGPU::isEntryFunctionCC(F->getCallingConv())) {
        FuncsToAlwaysInline.insert(F);
        Stack.push_back(F);
      }

      // No need to look at further users, but we do need to inline any callers.
      continue;
    }

    for (User *UU : U->users())
      Stack.push_back(UU);
  }
}

static bool isSafeToMove(Instruction *Inst, AliasAnalysis &AA,
                         SmallPtrSetImpl<Instruction *> &Stores) {

  if (Inst->mayWriteToMemory()) {
    Stores.insert(Inst);
    return false;
  }

  if (LoadInst *L = dyn_cast<LoadInst>(Inst)) {
    MemoryLocation Loc = MemoryLocation::get(L);
    for (Instruction *S : Stores)
      if (isModSet(AA.getModRefInfo(S, Loc)))
        return false;
  }

  if (Inst->isTerminator() || isa<PHINode>(Inst) || Inst->isEHPad() ||
      Inst->mayThrow())
    return false;

  if (auto *Call = dyn_cast<CallBase>(Inst)) {
    // Convergent operations cannot be made control-dependent on additional
    // values.
    if (Call->hasFnAttr(Attribute::Convergent))
      return false;

    for (Instruction *S : Stores)
      if (isModSet(AA.getModRefInfo(S, Call)))
        return false;
  }

  return true;
}

void MemorySSAUpdater::removeBlocks(
    const SmallPtrSetImpl<BasicBlock *> &DeadBlocks) {
  // First delete all uses of BB in MemoryPhis.
  for (BasicBlock *BB : DeadBlocks) {
    TerminatorInst *TI = BB->getTerminator();
    assert(TI && "Basic block expected to have a terminator instruction");
    for (BasicBlock *Succ : successors(TI))
      if (!DeadBlocks.count(Succ))
        if (MemoryPhi *MP = MSSA->getMemoryAccess(Succ)) {
          MP->unorderedDeleteIncomingBlock(BB);
          if (MP->getNumIncomingValues() == 1)
            removeMemoryAccess(MP);
        }
    // Drop all references of all accesses in BB
    if (MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB))
      for (MemoryAccess &MA : *Acc)
        MA.dropAllReferences();
  }

  // Next, delete all memory accesses in each block
  for (BasicBlock *BB : DeadBlocks) {
    MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB);
    if (!Acc)
      continue;
    for (auto AB = Acc->begin(), AE = Acc->end(); AB != AE;) {
      MemoryAccess *MA = &*AB;
      ++AB;
      MSSA->removeFromLookups(MA);
      MSSA->removeFromLists(MA);
    }
  }
}

SmallPtrSetImpl::SmallPtrSetImpl(const SmallPtrSetImpl& that) {
  NumElements = that.NumElements;
  NumTombstones = 0;
  if (that.isSmall()) {
    CurArraySize = that.CurArraySize;
    CurArray = &SmallArray[0];
    memcpy(CurArray, that.CurArray, sizeof(void*)*CurArraySize);
  } else {
    CurArraySize = that.NumElements < 64 ? 128 : that.NumElements*2;
    CurArray = new void*[CurArraySize+1];
    memset(CurArray, -1, CurArraySize*sizeof(void*));
    
    // The end pointer, always valid, is set to a valid element to help the
    // iterator.
    CurArray[CurArraySize] = 0;

    // Copy over all valid entries.
    for (void **BucketPtr = that.CurArray, **E = that.CurArray+CurArraySize;
         BucketPtr != E; ++BucketPtr) {
      // Copy over the element if it is valid.
      void *Elt = *BucketPtr;
      if (Elt != getTombstoneMarker() && Elt != getEmptyMarker())
        *const_cast<void**>(FindBucketFor(Elt)) = Elt;
    }
  }
}

/// Collect cast instructions that can be ignored in the vectorizer's cost
/// model, given a reduction exit value and the minimal type in which the
/// reduction can be represented.
static void collectCastsToIgnore(Loop *TheLoop, Instruction *Exit,
                                 Type *RecurrenceType,
                                 SmallPtrSetImpl<Instruction *> &Casts) {

  SmallVector<Instruction *, 8> Worklist;
  SmallPtrSet<Instruction *, 8> Visited;
  Worklist.push_back(Exit);

  while (!Worklist.empty()) {
    Instruction *Val = Worklist.pop_back_val();
    Visited.insert(Val);
    if (auto *Cast = dyn_cast<CastInst>(Val))
      if (Cast->getSrcTy() == RecurrenceType) {
        // If the source type of a cast instruction is equal to the recurrence
        // type, it will be eliminated, and should be ignored in the vectorizer
        // cost model.
        Casts.insert(Cast);
        continue;
      }

    // Add all operands to the work list if they are loop-varying values that
    // we haven't yet visited.
    for (Value *O : cast<User>(Val)->operands())
      if (auto *I = dyn_cast<Instruction>(O))
        if (TheLoop->contains(I) && !Visited.count(I))
          Worklist.push_back(I);
  }
}