C++ SmallVector::begin方法代码示例

// recurseBasicBlock() - This calculates the ProfileInfo estimation for a
// single block and then recurses into the successors.
// The algorithm preserves the flow condition, meaning that the sum of the
// weight of the incoming edges must be equal the block weight which must in
// turn be equal to the sume of the weights of the outgoing edges.
// Since the flow of an block is deterimined from the current state of the
// flow, once an edge has a flow assigned this flow is never changed again,
// otherwise it would be possible to violate the flow condition in another
// block.
void ProfileEstimatorPass::recurseBasicBlock(BasicBlock *BB) {

  // Break the recursion if this BasicBlock was already visited.
  if (BBToVisit.find(BB) == BBToVisit.end()) return;

  // Read the LoopInfo for this block.
  bool  BBisHeader = LI->isLoopHeader(BB);
  Loop* BBLoop     = LI->getLoopFor(BB);

  // To get the block weight, read all incoming edges.
  double BBWeight = 0;
  std::set<BasicBlock*> ProcessedPreds;
  for ( pred_iterator bbi = pred_begin(BB), bbe = pred_end(BB);
        bbi != bbe; ++bbi ) {
    // If this block was not considered already, add weight.
    Edge edge = getEdge(*bbi,BB);
    double w = getEdgeWeight(edge);
    if (ProcessedPreds.insert(*bbi).second) {
      BBWeight += ignoreMissing(w);
    }
    // If this block is a loop header and the predecessor is contained in this
    // loop, thus the edge is a backedge, continue and do not check if the
    // value is valid.
    if (BBisHeader && BBLoop->contains(*bbi)) {
      printEdgeError(edge, "but is backedge, continueing");
      continue;
    }
    // If the edges value is missing (and this is no loop header, and this is
    // no backedge) return, this block is currently non estimatable.
    if (w == MissingValue) {
      printEdgeError(edge, "returning");
      return;
    }
  }
  if (getExecutionCount(BB) != MissingValue) {
    BBWeight = getExecutionCount(BB);
  }

  // Fetch all necessary information for current block.
  SmallVector<Edge, 8> ExitEdges;
  SmallVector<Edge, 8> Edges;
  if (BBLoop) {
    BBLoop->getExitEdges(ExitEdges);
  }

  // If this is a loop header, consider the following:
  // Exactly the flow that is entering this block, must exit this block too. So
  // do the following: 
  // *) get all the exit edges, read the flow that is already leaving this
  // loop, remember the edges that do not have any flow on them right now.
  // (The edges that have already flow on them are most likely exiting edges of
  // other loops, do not touch those flows because the previously caclulated
  // loopheaders would not be exact anymore.)
  // *) In case there is not a single exiting edge left, create one at the loop
  // latch to prevent the flow from building up in the loop.
  // *) Take the flow that is not leaving the loop already and distribute it on
  // the remaining exiting edges.
  // (This ensures that all flow that enters the loop also leaves it.)
  // *) Increase the flow into the loop by increasing the weight of this block.
  // There is at least one incoming backedge that will bring us this flow later
  // on. (So that the flow condition in this node is valid again.)
  if (BBisHeader) {
    double incoming = BBWeight;
    // Subtract the flow leaving the loop.
    std::set<Edge> ProcessedExits;
    for (SmallVector<Edge, 8>::iterator ei = ExitEdges.begin(),
         ee = ExitEdges.end(); ei != ee; ++ei) {
      if (ProcessedExits.insert(*ei).second) {
        double w = getEdgeWeight(*ei);
        if (w == MissingValue) {
          Edges.push_back(*ei);
          // Check if there is a necessary minimal weight, if yes, subtract it 
          // from weight.
          if (MinimalWeight.find(*ei) != MinimalWeight.end()) {
            incoming -= MinimalWeight[*ei];
            DEBUG(dbgs() << "Reserving " << format("%.20g",MinimalWeight[*ei]) << " at " << (*ei) << "\n");
          }
        } else {
          incoming -= w;
        }
      }
    }
    // If no exit edges, create one:
    if (Edges.size() == 0) {
      BasicBlock *Latch = BBLoop->getLoopLatch();
      if (Latch) {
        Edge edge = getEdge(Latch,0);
        EdgeInformation[BB->getParent()][edge] = BBWeight;
        printEdgeWeight(edge);
        edge = getEdge(Latch, BB);
        EdgeInformation[BB->getParent()][edge] = BBWeight * ExecCount;
//.........这里部分代码省略.........

/// Parse a function definition signature.
///   func-signature:
///     func-arguments func-throws? func-signature-result?
///   func-signature-result:
///     '->' type
///
/// Note that this leaves retType as null if unspecified.
ParserStatus
Parser::parseFunctionSignature(Identifier SimpleName,
                               DeclName &FullName,
                               SmallVectorImpl<ParameterList*> &bodyParams,
                               DefaultArgumentInfo &defaultArgs,
                               SourceLoc &throwsLoc,
                               bool &rethrows,
                               TypeRepr *&retType) {
  SmallVector<Identifier, 4> NamePieces;
  NamePieces.push_back(SimpleName);
  FullName = SimpleName;
  
  ParserStatus Status;
  // We force first type of a func declaration to be a tuple for consistency.
  if (Tok.is(tok::l_paren)) {
    ParameterContextKind paramContext;
    if (SimpleName.isOperator())
      paramContext = ParameterContextKind::Operator;
    else
      paramContext = ParameterContextKind::Function;

    Status = parseFunctionArguments(NamePieces, bodyParams, paramContext,
                                    defaultArgs);
    FullName = DeclName(Context, SimpleName, 
                        llvm::makeArrayRef(NamePieces.begin() + 1,
                                           NamePieces.end()));

    if (bodyParams.empty()) {
      // If we didn't get anything, add a () pattern to avoid breaking
      // invariants.
      assert(Status.hasCodeCompletion() || Status.isError());
      bodyParams.push_back(ParameterList::createEmpty(Context));
    }
  } else {
    diagnose(Tok, diag::func_decl_without_paren);
    Status = makeParserError();

    // Recover by creating a '() -> ?' signature.
    bodyParams.push_back(ParameterList::createEmpty(Context, PreviousLoc,
                                                    PreviousLoc));
    FullName = DeclName(Context, SimpleName, bodyParams.back());
  }
  
  // Check for the 'throws' keyword.
  rethrows = false;
  if (Tok.is(tok::kw_throws)) {
    throwsLoc = consumeToken();
  } else if (Tok.is(tok::kw_rethrows)) {
    throwsLoc = consumeToken();
    rethrows = true;
  } else if (Tok.is(tok::kw_throw)) {
    throwsLoc = consumeToken();
    diagnose(throwsLoc, diag::throw_in_function_type)
      .fixItReplace(throwsLoc, "throws");
  }

  SourceLoc arrowLoc;
  // If there's a trailing arrow, parse the rest as the result type.
  if (Tok.isAny(tok::arrow, tok::colon)) {
    if (!consumeIf(tok::arrow, arrowLoc)) {
      // FixIt ':' to '->'.
      diagnose(Tok, diag::func_decl_expected_arrow)
          .fixItReplace(SourceRange(Tok.getLoc()), "->");
      arrowLoc = consumeToken(tok::colon);
    }

    ParserResult<TypeRepr> ResultType =
      parseType(diag::expected_type_function_result);
    if (ResultType.hasCodeCompletion())
      return ResultType;
    retType = ResultType.getPtrOrNull();
    if (!retType) {
      Status.setIsParseError();
      return Status;
    }
  } else {
    // Otherwise, we leave retType null.
    retType = nullptr;
  }

  // Check for 'throws' and 'rethrows' after the type and correct it.
  if (!throwsLoc.isValid()) {
    if (Tok.is(tok::kw_throws)) {
      throwsLoc = consumeToken();
    } else if (Tok.is(tok::kw_rethrows)) {
      throwsLoc = consumeToken();
      rethrows = true;
    }

    if (throwsLoc.isValid()) {
      assert(arrowLoc.isValid());
      assert(retType);
      auto diag = rethrows ? diag::rethrows_after_function_result
//.........这里部分代码省略.........

bool LoopInterchangeTransform::adjustLoopBranches() {

    DEBUG(dbgs() << "adjustLoopBranches called\n");
    // Adjust the loop preheader
    BasicBlock *InnerLoopHeader = InnerLoop->getHeader();
    BasicBlock *OuterLoopHeader = OuterLoop->getHeader();
    BasicBlock *InnerLoopLatch = InnerLoop->getLoopLatch();
    BasicBlock *OuterLoopLatch = OuterLoop->getLoopLatch();
    BasicBlock *OuterLoopPreHeader = OuterLoop->getLoopPreheader();
    BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
    BasicBlock *OuterLoopPredecessor = OuterLoopPreHeader->getUniquePredecessor();
    BasicBlock *InnerLoopLatchPredecessor =
        InnerLoopLatch->getUniquePredecessor();
    BasicBlock *InnerLoopLatchSuccessor;
    BasicBlock *OuterLoopLatchSuccessor;

    BranchInst *OuterLoopLatchBI =
        dyn_cast<BranchInst>(OuterLoopLatch->getTerminator());
    BranchInst *InnerLoopLatchBI =
        dyn_cast<BranchInst>(InnerLoopLatch->getTerminator());
    BranchInst *OuterLoopHeaderBI =
        dyn_cast<BranchInst>(OuterLoopHeader->getTerminator());
    BranchInst *InnerLoopHeaderBI =
        dyn_cast<BranchInst>(InnerLoopHeader->getTerminator());

    if (!OuterLoopPredecessor || !InnerLoopLatchPredecessor ||
            !OuterLoopLatchBI || !InnerLoopLatchBI || !OuterLoopHeaderBI ||
            !InnerLoopHeaderBI)
        return false;

    BranchInst *InnerLoopLatchPredecessorBI =
        dyn_cast<BranchInst>(InnerLoopLatchPredecessor->getTerminator());
    BranchInst *OuterLoopPredecessorBI =
        dyn_cast<BranchInst>(OuterLoopPredecessor->getTerminator());

    if (!OuterLoopPredecessorBI || !InnerLoopLatchPredecessorBI)
        return false;
    BasicBlock *InnerLoopHeaderSuccessor = InnerLoopHeader->getUniqueSuccessor();
    if (!InnerLoopHeaderSuccessor)
        return false;

    // Adjust Loop Preheader and headers

    unsigned NumSucc = OuterLoopPredecessorBI->getNumSuccessors();
    for (unsigned i = 0; i < NumSucc; ++i) {
        if (OuterLoopPredecessorBI->getSuccessor(i) == OuterLoopPreHeader)
            OuterLoopPredecessorBI->setSuccessor(i, InnerLoopPreHeader);
    }

    NumSucc = OuterLoopHeaderBI->getNumSuccessors();
    for (unsigned i = 0; i < NumSucc; ++i) {
        if (OuterLoopHeaderBI->getSuccessor(i) == OuterLoopLatch)
            OuterLoopHeaderBI->setSuccessor(i, LoopExit);
        else if (OuterLoopHeaderBI->getSuccessor(i) == InnerLoopPreHeader)
            OuterLoopHeaderBI->setSuccessor(i, InnerLoopHeaderSuccessor);
    }

    // Adjust reduction PHI's now that the incoming block has changed.
    updateIncomingBlock(InnerLoopHeaderSuccessor, InnerLoopHeader,
                        OuterLoopHeader);

    BranchInst::Create(OuterLoopPreHeader, InnerLoopHeaderBI);
    InnerLoopHeaderBI->eraseFromParent();

    // -------------Adjust loop latches-----------
    if (InnerLoopLatchBI->getSuccessor(0) == InnerLoopHeader)
        InnerLoopLatchSuccessor = InnerLoopLatchBI->getSuccessor(1);
    else
        InnerLoopLatchSuccessor = InnerLoopLatchBI->getSuccessor(0);

    NumSucc = InnerLoopLatchPredecessorBI->getNumSuccessors();
    for (unsigned i = 0; i < NumSucc; ++i) {
        if (InnerLoopLatchPredecessorBI->getSuccessor(i) == InnerLoopLatch)
            InnerLoopLatchPredecessorBI->setSuccessor(i, InnerLoopLatchSuccessor);
    }

    // Adjust PHI nodes in InnerLoopLatchSuccessor. Update all uses of PHI with
    // the value and remove this PHI node from inner loop.
    SmallVector<PHINode *, 8> LcssaVec;
    for (auto I = InnerLoopLatchSuccessor->begin(); isa<PHINode>(I); ++I) {
        PHINode *LcssaPhi = cast<PHINode>(I);
        LcssaVec.push_back(LcssaPhi);
    }
    for (auto I = LcssaVec.begin(), E = LcssaVec.end(); I != E; ++I) {
        PHINode *P = *I;
        Value *Incoming = P->getIncomingValueForBlock(InnerLoopLatch);
        P->replaceAllUsesWith(Incoming);
        P->eraseFromParent();
    }

    if (OuterLoopLatchBI->getSuccessor(0) == OuterLoopHeader)
        OuterLoopLatchSuccessor = OuterLoopLatchBI->getSuccessor(1);
    else
        OuterLoopLatchSuccessor = OuterLoopLatchBI->getSuccessor(0);

    if (InnerLoopLatchBI->getSuccessor(1) == InnerLoopLatchSuccessor)
        InnerLoopLatchBI->setSuccessor(1, OuterLoopLatchSuccessor);
    else
        InnerLoopLatchBI->setSuccessor(0, OuterLoopLatchSuccessor);

//.........这里部分代码省略.........

/// InsertUnwindResumeCalls - Convert the ResumeInsts that are still present
/// into calls to the appropriate _Unwind_Resume function.
bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
    bool UsesNewEH = false;
    SmallVector<ResumeInst*, 16> Resumes;
    for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
        TerminatorInst *TI = I->getTerminator();
        if (ResumeInst *RI = dyn_cast<ResumeInst>(TI))
            Resumes.push_back(RI);
        else if (InvokeInst *II = dyn_cast<InvokeInst>(TI))
            UsesNewEH = II->getUnwindDest()->isLandingPad();
    }

    if (Resumes.empty())
        return UsesNewEH;

    // Find the rewind function if we didn't already.
    if (!RewindFunction) {
        LLVMContext &Ctx = Resumes[0]->getContext();
        FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
                                              Type::getInt8PtrTy(Ctx), false);
        const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
        RewindFunction = Fn.getParent()->getOrInsertFunction(RewindName, FTy);
    }

    // Create the basic block where the _Unwind_Resume call will live.
    LLVMContext &Ctx = Fn.getContext();
    unsigned ResumesSize = Resumes.size();

    if (ResumesSize == 1) {
        // Instead of creating a new BB and PHI node, just append the call to
        // _Unwind_Resume to the end of the single resume block.
        ResumeInst *RI = Resumes.front();
        BasicBlock *UnwindBB = RI->getParent();
        Value *ExnObj = GetExceptionObject(RI);

        // Call the _Unwind_Resume function.
        CallInst *CI = CallInst::Create(RewindFunction, ExnObj, "", UnwindBB);
        CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));

        // We never expect _Unwind_Resume to return.
        new UnreachableInst(Ctx, UnwindBB);
        return true;
    }

    BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn);
    PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesSize,
                                  "exn.obj", UnwindBB);

    // Extract the exception object from the ResumeInst and add it to the PHI node
    // that feeds the _Unwind_Resume call.
    for (SmallVectorImpl<ResumeInst*>::iterator
            I = Resumes.begin(), E = Resumes.end(); I != E; ++I) {
        ResumeInst *RI = *I;
        BasicBlock *Parent = RI->getParent();
        BranchInst::Create(UnwindBB, Parent);

        Value *ExnObj = GetExceptionObject(RI);
        PN->addIncoming(ExnObj, Parent);

        ++NumResumesLowered;
    }

    // Call the function.
    CallInst *CI = CallInst::Create(RewindFunction, PN, "", UnwindBB);
    CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));

    // We never expect _Unwind_Resume to return.
    new UnreachableInst(Ctx, UnwindBB);
    return true;
}

unsigned char* JITDwarfEmitter::EmitExceptionTable(MachineFunction* MF,
                                         unsigned char* StartFunction,
                                         unsigned char* EndFunction) const {
  assert(MMI && "MachineModuleInfo not registered!");

  // Map all labels and get rid of any dead landing pads.
  MMI->TidyLandingPads(JCE->getLabelLocations());

  const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
  const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
  const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
  if (PadInfos.empty()) return 0;

  // Sort the landing pads in order of their type ids.  This is used to fold
  // duplicate actions.
  SmallVector<const LandingPadInfo *, 64> LandingPads;
  LandingPads.reserve(PadInfos.size());
  for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
    LandingPads.push_back(&PadInfos[i]);
  std::sort(LandingPads.begin(), LandingPads.end(), PadLT);

  // Negative type ids index into FilterIds, positive type ids index into
  // TypeInfos.  The value written for a positive type id is just the type
  // id itself.  For a negative type id, however, the value written is the
  // (negative) byte offset of the corresponding FilterIds entry.  The byte
  // offset is usually equal to the type id, because the FilterIds entries
  // are written using a variable width encoding which outputs one byte per
  // entry as long as the value written is not too large, but can differ.
  // This kind of complication does not occur for positive type ids because
  // type infos are output using a fixed width encoding.
  // FilterOffsets[i] holds the byte offset corresponding to FilterIds[i].
  SmallVector<int, 16> FilterOffsets;
  FilterOffsets.reserve(FilterIds.size());
  int Offset = -1;
  for(std::vector<unsigned>::const_iterator I = FilterIds.begin(),
    E = FilterIds.end(); I != E; ++I) {
    FilterOffsets.push_back(Offset);
    Offset -= MCAsmInfo::getULEB128Size(*I);
  }

  // Compute the actions table and gather the first action index for each
  // landing pad site.
  SmallVector<ActionEntry, 32> Actions;
  SmallVector<unsigned, 64> FirstActions;
  FirstActions.reserve(LandingPads.size());

  int FirstAction = 0;
  unsigned SizeActions = 0;
  for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
    const LandingPadInfo *LP = LandingPads[i];
    const std::vector<int> &TypeIds = LP->TypeIds;
    const unsigned NumShared = i ? SharedTypeIds(LP, LandingPads[i-1]) : 0;
    unsigned SizeSiteActions = 0;

    if (NumShared < TypeIds.size()) {
      unsigned SizeAction = 0;
      ActionEntry *PrevAction = 0;

      if (NumShared) {
        const unsigned SizePrevIds = LandingPads[i-1]->TypeIds.size();
        assert(Actions.size());
        PrevAction = &Actions.back();
        SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
          MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
        for (unsigned j = NumShared; j != SizePrevIds; ++j) {
          SizeAction -= MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
          SizeAction += -PrevAction->NextAction;
          PrevAction = PrevAction->Previous;
        }
      }

      // Compute the actions.
      for (unsigned I = NumShared, M = TypeIds.size(); I != M; ++I) {
        int TypeID = TypeIds[I];
        assert(-1-TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
        int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
        unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);

        int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
        SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
        SizeSiteActions += SizeAction;

        ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
        Actions.push_back(Action);

        PrevAction = &Actions.back();
      }

      // Record the first action of the landing pad site.
      FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
    } // else identical - re-use previous FirstAction

    FirstActions.push_back(FirstAction);

    // Compute this sites contribution to size.
    SizeActions += SizeSiteActions;
  }

  // Compute the call-site table.  Entries must be ordered by address.
  SmallVector<CallSiteEntry, 64> CallSites;
//.........这里部分代码省略.........

static void lookupInModule(ModuleDecl *module, ModuleDecl::AccessPathTy accessPath,
                           SmallVectorImpl<ValueDecl *> &decls,
                           ResolutionKind resolutionKind, bool canReturnEarly,
                           LazyResolver *typeResolver,
                           ModuleLookupCache &cache,
                           const DeclContext *moduleScopeContext,
                           bool respectAccessControl,
                           ArrayRef<ModuleDecl::ImportedModule> extraImports,
                           CallbackTy callback) {
  assert(module);
  assert(std::none_of(extraImports.begin(), extraImports.end(),
                      [](ModuleDecl::ImportedModule import) -> bool {
    return !import.second;
  }));

  ModuleLookupCache::iterator iter;
  bool isNew;
  std::tie(iter, isNew) = cache.insert({{accessPath, module}, {}});
  if (!isNew) {
    decls.append(iter->second.begin(), iter->second.end());
    return;
  }

  size_t initialCount = decls.size();

  SmallVector<ValueDecl *, 4> localDecls;
  callback(module, accessPath, localDecls);
  if (respectAccessControl) {
    auto newEndIter = std::remove_if(localDecls.begin(), localDecls.end(),
                                    [=](ValueDecl *VD) {
      return !VD->isAccessibleFrom(moduleScopeContext);
    });
    localDecls.erase(newEndIter, localDecls.end());

    // This only applies to immediate imports of the top-level module.
    if (moduleScopeContext && moduleScopeContext->getParentModule() != module)
      moduleScopeContext = nullptr;
  }

  OverloadSetTy overloads;
  resolutionKind = recordImportDecls(typeResolver, decls, localDecls,
                                     overloads, resolutionKind);

  bool foundDecls = decls.size() > initialCount;
  if (!foundDecls || !canReturnEarly ||
      resolutionKind == ResolutionKind::Overloadable) {
    SmallVector<ModuleDecl::ImportedModule, 8> reexports;
    module->getImportedModulesForLookup(reexports);
    assert(std::none_of(reexports.begin(), reexports.end(),
                        [](ModuleDecl::ImportedModule import) -> bool {
      return !import.second;
    }));
    reexports.append(extraImports.begin(), extraImports.end());

    // Prefer scoped imports (import func Swift.max) to whole-module imports.
    SmallVector<ValueDecl *, 8> unscopedValues;
    SmallVector<ValueDecl *, 8> scopedValues;
    for (auto next : reexports) {
      // Filter any whole-module imports, and skip specific-decl imports if the
      // import path doesn't match exactly.
      ModuleDecl::AccessPathTy combinedAccessPath;
      if (accessPath.empty()) {
        combinedAccessPath = next.first;
      } else if (!next.first.empty() &&
                 !ModuleDecl::isSameAccessPath(next.first, accessPath)) {
        // If we ever allow importing non-top-level decls, it's possible the
        // rule above isn't what we want.
        assert(next.first.size() == 1 && "import of non-top-level decl");
        continue;
      } else {
        combinedAccessPath = accessPath;
      }

      auto &resultSet = next.first.empty() ? unscopedValues : scopedValues;
      lookupInModule<OverloadSetTy>(next.second, combinedAccessPath,
                                    resultSet, resolutionKind, canReturnEarly,
                                    typeResolver, cache, moduleScopeContext,
                                    respectAccessControl, {}, callback);
    }

    // Add the results from scoped imports.
    resolutionKind = recordImportDecls(typeResolver, decls, scopedValues,
                                       overloads, resolutionKind);

    // Add the results from unscoped imports.
    foundDecls = decls.size() > initialCount;
    if (!foundDecls || !canReturnEarly ||
        resolutionKind == ResolutionKind::Overloadable) {
      resolutionKind = recordImportDecls(typeResolver, decls, unscopedValues,
                                         overloads, resolutionKind);
    }
  }

  // Remove duplicated declarations.
  llvm::SmallPtrSet<ValueDecl *, 4> knownDecls;
  decls.erase(std::remove_if(decls.begin() + initialCount, decls.end(),
                             [&](ValueDecl *d) -> bool { 
                               return !knownDecls.insert(d).second;
                             }),
              decls.end());
//.........这里部分代码省略.........

/// Emit landing pads and actions.
///
/// The general organization of the table is complex, but the basic concepts are
/// easy.  First there is a header which describes the location and organization
/// of the three components that follow.
///
///  1. The landing pad site information describes the range of code covered by
///     the try.  In our case it's an accumulation of the ranges covered by the
///     invokes in the try.  There is also a reference to the landing pad that
///     handles the exception once processed.  Finally an index into the actions
///     table.
///  2. The action table, in our case, is composed of pairs of type IDs and next
///     action offset.  Starting with the action index from the landing pad
///     site, each type ID is checked for a match to the current exception.  If
///     it matches then the exception and type id are passed on to the landing
///     pad.  Otherwise the next action is looked up.  This chain is terminated
///     with a next action of zero.  If no type id is found then the frame is
///     unwound and handling continues.
///  3. Type ID table contains references to all the C++ typeinfo for all
///     catches in the function.  This tables is reverse indexed base 1.
void EHStreamer::emitExceptionTable() {
  const std::vector<const GlobalValue *> &TypeInfos = MMI->getTypeInfos();
  const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
  const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();

  // Sort the landing pads in order of their type ids.  This is used to fold
  // duplicate actions.
  SmallVector<const LandingPadInfo *, 64> LandingPads;
  LandingPads.reserve(PadInfos.size());

  for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
    LandingPads.push_back(&PadInfos[i]);

  // Order landing pads lexicographically by type id.
  std::sort(LandingPads.begin(), LandingPads.end(),
            [](const LandingPadInfo *L,
               const LandingPadInfo *R) { return L->TypeIds < R->TypeIds; });

  // Compute the actions table and gather the first action index for each
  // landing pad site.
  SmallVector<ActionEntry, 32> Actions;
  SmallVector<unsigned, 64> FirstActions;
  unsigned SizeActions =
    computeActionsTable(LandingPads, Actions, FirstActions);

  // Compute the call-site table.
  SmallVector<CallSiteEntry, 64> CallSites;
  computeCallSiteTable(CallSites, LandingPads, FirstActions);

  // Final tallies.

  // Call sites.
  bool IsSJLJ = Asm->MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
  bool HaveTTData = IsSJLJ ? (!TypeInfos.empty() || !FilterIds.empty()) : true;

  unsigned CallSiteTableLength;
  if (IsSJLJ)
    CallSiteTableLength = 0;
  else {
    unsigned SiteStartSize  = 4; // dwarf::DW_EH_PE_udata4
    unsigned SiteLengthSize = 4; // dwarf::DW_EH_PE_udata4
    unsigned LandingPadSize = 4; // dwarf::DW_EH_PE_udata4
    CallSiteTableLength =
      CallSites.size() * (SiteStartSize + SiteLengthSize + LandingPadSize);
  }

  for (unsigned i = 0, e = CallSites.size(); i < e; ++i) {
    CallSiteTableLength += getULEB128Size(CallSites[i].Action);
    if (IsSJLJ)
      CallSiteTableLength += getULEB128Size(i);
  }

  // Type infos.
  const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
  unsigned TTypeEncoding;
  unsigned TypeFormatSize;

  if (!HaveTTData) {
    // For SjLj exceptions, if there is no TypeInfo, then we just explicitly say
    // that we're omitting that bit.
    TTypeEncoding = dwarf::DW_EH_PE_omit;
    // dwarf::DW_EH_PE_absptr
    TypeFormatSize = Asm->getDataLayout().getPointerSize();
  } else {
    // Okay, we have actual filters or typeinfos to emit.  As such, we need to
    // pick a type encoding for them.  We're about to emit a list of pointers to
    // typeinfo objects at the end of the LSDA.  However, unless we're in static
    // mode, this reference will require a relocation by the dynamic linker.
    //
    // Because of this, we have a couple of options:
    //
    //   1) If we are in -static mode, we can always use an absolute reference
    //      from the LSDA, because the static linker will resolve it.
    //
    //   2) Otherwise, if the LSDA section is writable, we can output the direct
    //      reference to the typeinfo and allow the dynamic linker to relocate
    //      it.  Since it is in a writable section, the dynamic linker won't
    //      have a problem.
    //
    //   3) Finally, if we're in PIC mode and the LDSA section isn't writable,
//.........这里部分代码省略.........

static void emitImplicitValueConstructor(SILGenFunction &gen,
                                         ConstructorDecl *ctor) {
  RegularLocation Loc(ctor);
  Loc.markAutoGenerated();
  // FIXME: Handle 'self' along with the other arguments.
  auto *paramList = ctor->getParameterList(1);
  auto selfTyCan = ctor->getImplicitSelfDecl()->getType()->getInOutObjectType();
  SILType selfTy = gen.getLoweredType(selfTyCan);

  // Emit the indirect return argument, if any.
  SILValue resultSlot;
  if (selfTy.isAddressOnly(gen.SGM.M)) {
    auto &AC = gen.getASTContext();
    auto VD = new (AC) ParamDecl(/*IsLet*/ false, SourceLoc(),
                                 AC.getIdentifier("$return_value"),
                                 SourceLoc(),
                                 AC.getIdentifier("$return_value"), selfTyCan,
                                 ctor);
    resultSlot = new (gen.F.getModule()) SILArgument(gen.F.begin(), selfTy, VD);
  }

  // Emit the elementwise arguments.
  SmallVector<RValue, 4> elements;
  for (size_t i = 0, size = paramList->size(); i < size; ++i) {
    auto &param = paramList->get(i);

    elements.push_back(
      emitImplicitValueConstructorArg(gen, Loc,
                                      param.decl->getType()->getCanonicalType(),
                                      ctor));
  }

  emitConstructorMetatypeArg(gen, ctor);

  auto *decl = selfTy.getStructOrBoundGenericStruct();
  assert(decl && "not a struct?!");

  // If we have an indirect return slot, initialize it in-place.
  if (resultSlot) {

    auto elti = elements.begin(), eltEnd = elements.end();
    for (VarDecl *field : decl->getStoredProperties()) {
      auto fieldTy = selfTy.getFieldType(field, gen.SGM.M);
      auto &fieldTL = gen.getTypeLowering(fieldTy);
      SILValue slot = gen.B.createStructElementAddr(Loc, resultSlot, field,
                                                    fieldTL.getLoweredType().getAddressType());
      InitializationPtr init(new KnownAddressInitialization(slot));

      // An initialized 'let' property has a single value specified by the
      // initializer - it doesn't come from an argument.
      if (!field->isStatic() && field->isLet() &&
          field->getParentInitializer()) {
        assert(field->getType()->isEqual(field->getParentInitializer()
                                         ->getType()) && "Checked by sema");

        // Cleanup after this initialization.
        FullExpr scope(gen.Cleanups, field->getParentPatternBinding());
        gen.emitRValue(field->getParentInitializer())
          .forwardInto(gen, init.get(), Loc);
        continue;
      }

      assert(elti != eltEnd && "number of args does not match number of fields");
      (void)eltEnd;
      std::move(*elti).forwardInto(gen, init.get(), Loc);
      ++elti;
    }
    gen.B.createReturn(ImplicitReturnLocation::getImplicitReturnLoc(Loc),
                       gen.emitEmptyTuple(Loc));
    return;
  }

  // Otherwise, build a struct value directly from the elements.
  SmallVector<SILValue, 4> eltValues;

  auto elti = elements.begin(), eltEnd = elements.end();
  for (VarDecl *field : decl->getStoredProperties()) {
    auto fieldTy = selfTy.getFieldType(field, gen.SGM.M);
    SILValue v;

    // An initialized 'let' property has a single value specified by the
    // initializer - it doesn't come from an argument.
    if (!field->isStatic() && field->isLet() && field->getParentInitializer()) {
      // Cleanup after this initialization.
      FullExpr scope(gen.Cleanups, field->getParentPatternBinding());
      v = gen.emitRValue(field->getParentInitializer())
             .forwardAsSingleStorageValue(gen, fieldTy, Loc);
    } else {
      assert(elti != eltEnd && "number of args does not match number of fields");
      (void)eltEnd;
      v = std::move(*elti).forwardAsSingleStorageValue(gen, fieldTy, Loc);
      ++elti;
    }

    eltValues.push_back(v);
  }

  SILValue selfValue = gen.B.createStruct(Loc, selfTy, eltValues);
  gen.B.createReturn(ImplicitReturnLocation::getImplicitReturnLoc(Loc),
                     selfValue);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        // A reduction operation must only have one use of the reduction value.
        if (!IsAPhi && Kind != RK_IntegerMinMax && Kind != RK_FloatMinMax &&
                hasMultipleUsesOf(Cur, VisitedInsts))
            return false;

        // All inputs to a PHI node must be a reduction value.
        if (IsAPhi && Cur != Phi && !areAllUsesIn(Cur, VisitedInsts))
            return false;

        if (Kind == RK_IntegerMinMax &&
                (isa<ICmpInst>(Cur) || isa<SelectInst>(Cur)))
            ++NumCmpSelectPatternInst;
        if (Kind == RK_FloatMinMax && (isa<FCmpInst>(Cur) || isa<SelectInst>(Cur)))
            ++NumCmpSelectPatternInst;

        // Check  whether we found a reduction operator.
        FoundReduxOp |= !IsAPhi && Cur != Start;

        // Process users of current instruction. Push non-PHI nodes after PHI nodes
        // onto the stack. This way we are going to have seen all inputs to PHI
        // nodes once we get to them.
        SmallVector<Instruction *, 8> NonPHIs;
        SmallVector<Instruction *, 8> PHIs;
        for (User *U : Cur->users()) {
            Instruction *UI = cast<Instruction>(U);

            // Check if we found the exit user.
            BasicBlock *Parent = UI->getParent();
            if (!TheLoop->contains(Parent)) {
                // Exit if you find multiple outside users or if the header phi node is
                // being used. In this case the user uses the value of the previous
                // iteration, in which case we would loose "VF-1" iterations of the
                // reduction operation if we vectorize.
                if (ExitInstruction != nullptr || Cur == Phi)
                    return false;

                // The instruction used by an outside user must be the last instruction
                // before we feed back to the reduction phi. Otherwise, we loose VF-1
                // operations on the value.
                if (!is_contained(Phi->operands(), Cur))
                    return false;

                ExitInstruction = Cur;
                continue;
            }

            // Process instructions only once (termination). Each reduction cycle
            // value must only be used once, except by phi nodes and min/max
            // reductions which are represented as a cmp followed by a select.
            InstDesc IgnoredVal(false, nullptr);
            if (VisitedInsts.insert(UI).second) {
                if (isa<PHINode>(UI))
                    PHIs.push_back(UI);
                else
                    NonPHIs.push_back(UI);
            } else if (!isa<PHINode>(UI) &&
                       ((!isa<FCmpInst>(UI) && !isa<ICmpInst>(UI) &&
                         !isa<SelectInst>(UI)) ||
                        !isMinMaxSelectCmpPattern(UI, IgnoredVal).isRecurrence()))
                return false;

            // Remember that we completed the cycle.
            if (UI == Phi)
                FoundStartPHI = true;
        }
        Worklist.append(PHIs.begin(), PHIs.end());
        Worklist.append(NonPHIs.begin(), NonPHIs.end());
    }

    // This means we have seen one but not the other instruction of the
    // pattern or more than just a select and cmp.
    if ((Kind == RK_IntegerMinMax || Kind == RK_FloatMinMax) &&
            NumCmpSelectPatternInst != 2)
        return false;

    if (!FoundStartPHI || !FoundReduxOp || !ExitInstruction)
        return false;

    // If we think Phi may have been type-promoted, we also need to ensure that
    // all source operands of the reduction are either SExtInsts or ZEstInsts. If
    // so, we will be able to evaluate the reduction in the narrower bit width.
    if (Start != Phi)
        if (!getSourceExtensionKind(Start, ExitInstruction, RecurrenceType,
                                    IsSigned, VisitedInsts, CastInsts))
            return false;

    // We found a reduction var if we have reached the original phi node and we
    // only have a single instruction with out-of-loop users.

    // The ExitInstruction(Instruction which is allowed to have out-of-loop users)
    // is saved as part of the RecurrenceDescriptor.

    // Save the description of this reduction variable.
    RecurrenceDescriptor RD(
        RdxStart, ExitInstruction, Kind, ReduxDesc.getMinMaxKind(),
        ReduxDesc.getUnsafeAlgebraInst(), RecurrenceType, IsSigned, CastInsts);
    RedDes = RD;

    return true;
}

int main(int argc_, const char **argv_) {
  llvm::sys::PrintStackTraceOnErrorSignal();
  llvm::PrettyStackTraceProgram X(argc_, argv_);

  std::set<std::string> SavedStrings;
  SmallVector<const char*, 256> argv;

  ExpandArgv(argc_, argv_, argv, SavedStrings);

  // Handle -cc1 integrated tools.
  if (argv.size() > 1 && StringRef(argv[1]).startswith("-cc1")) {
    StringRef Tool = argv[1] + 4;

    if (Tool == "")
      return cc1_main(argv.data()+2, argv.data()+argv.size(), argv[0],
                      (void*) (intptr_t) GetExecutablePath);
    if (Tool == "as")
      return cc1as_main(argv.data()+2, argv.data()+argv.size(), argv[0],
                      (void*) (intptr_t) GetExecutablePath);

    // Reject unknown tools.
    llvm::errs() << "error: unknown integrated tool '" << Tool << "'\n";
    return 1;
  }

  bool CanonicalPrefixes = true;
  for (int i = 1, size = argv.size(); i < size; ++i) {
    if (StringRef(argv[i]) == "-no-canonical-prefixes") {
      CanonicalPrefixes = false;
      break;
    }
  }

  llvm::sys::Path Path = GetExecutablePath(argv[0], CanonicalPrefixes);

  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions;
  {
    // Note that ParseDiagnosticArgs() uses the cc1 option table.
    OwningPtr<OptTable> CC1Opts(createDriverOptTable());
    unsigned MissingArgIndex, MissingArgCount;
    OwningPtr<InputArgList> Args(CC1Opts->ParseArgs(argv.begin()+1, argv.end(),
                                            MissingArgIndex, MissingArgCount));
    // We ignore MissingArgCount and the return value of ParseDiagnosticArgs.
    // Any errors that would be diagnosed here will also be diagnosed later,
    // when the DiagnosticsEngine actually exists.
    (void) ParseDiagnosticArgs(*DiagOpts, *Args);
  }
  // Now we can create the DiagnosticsEngine with a properly-filled-out
  // DiagnosticOptions instance.
  TextDiagnosticPrinter *DiagClient
    = new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
  DiagClient->setPrefix(llvm::sys::path::stem(Path.str()));
  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());

  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
  ProcessWarningOptions(Diags, *DiagOpts);

#ifdef CLANG_IS_PRODUCTION
  const bool IsProduction = true;
#else
  const bool IsProduction = false;
#endif
  Driver TheDriver(Path.str(), llvm::sys::getDefaultTargetTriple(),
                   "a.out", IsProduction, Diags);

  // Attempt to find the original path used to invoke the driver, to determine
  // the installed path. We do this manually, because we want to support that
  // path being a symlink.
  {
    SmallString<128> InstalledPath(argv[0]);

    // Do a PATH lookup, if there are no directory components.
    if (llvm::sys::path::filename(InstalledPath) == InstalledPath) {
      llvm::sys::Path Tmp = llvm::sys::Program::FindProgramByName(
        llvm::sys::path::filename(InstalledPath.str()));
      if (!Tmp.empty())
        InstalledPath = Tmp.str();
    }
    llvm::sys::fs::make_absolute(InstalledPath);
    InstalledPath = llvm::sys::path::parent_path(InstalledPath);
    bool exists;
    if (!llvm::sys::fs::exists(InstalledPath.str(), exists) && exists)
      TheDriver.setInstalledDir(InstalledPath);
  }

  llvm::InitializeAllTargets();
  ParseProgName(argv, SavedStrings, TheDriver);

  // Handle CC_PRINT_OPTIONS and CC_PRINT_OPTIONS_FILE.
  TheDriver.CCPrintOptions = !!::getenv("CC_PRINT_OPTIONS");
  if (TheDriver.CCPrintOptions)
    TheDriver.CCPrintOptionsFilename = ::getenv("CC_PRINT_OPTIONS_FILE");

  // Handle CC_PRINT_HEADERS and CC_PRINT_HEADERS_FILE.
  TheDriver.CCPrintHeaders = !!::getenv("CC_PRINT_HEADERS");
  if (TheDriver.CCPrintHeaders)
    TheDriver.CCPrintHeadersFilename = ::getenv("CC_PRINT_HEADERS_FILE");

  // Handle CC_LOG_DIAGNOSTICS and CC_LOG_DIAGNOSTICS_FILE.
  TheDriver.CCLogDiagnostics = !!::getenv("CC_LOG_DIAGNOSTICS");
//.........这里部分代码省略.........

/// optimizeExtInstr - If instruction is a copy-like instruction, i.e. it reads
/// a single register and writes a single register and it does not modify the
/// source, and if the source value is preserved as a sub-register of the
/// result, then replace all reachable uses of the source with the subreg of the
/// result.
///
/// Do not generate an EXTRACT that is used only in a debug use, as this changes
/// the code. Since this code does not currently share EXTRACTs, just ignore all
/// debug uses.
bool PeepholeOptimizer::
optimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
                 SmallPtrSet<MachineInstr*, 8> &LocalMIs) {
  unsigned SrcReg, DstReg, SubIdx;
  if (!TII->isCoalescableExtInstr(*MI, SrcReg, DstReg, SubIdx))
    return false;

  if (TargetRegisterInfo::isPhysicalRegister(DstReg) ||
      TargetRegisterInfo::isPhysicalRegister(SrcReg))
    return false;

  MachineRegisterInfo::use_nodbg_iterator UI = MRI->use_nodbg_begin(SrcReg);
  if (++UI == MRI->use_nodbg_end())
    // No other uses.
    return false;

  // The source has other uses. See if we can replace the other uses with use of
  // the result of the extension.
  SmallPtrSet<MachineBasicBlock*, 4> ReachedBBs;
  UI = MRI->use_nodbg_begin(DstReg);
  for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end();
       UI != UE; ++UI)
    ReachedBBs.insert(UI->getParent());

  // Uses that are in the same BB of uses of the result of the instruction.
  SmallVector<MachineOperand*, 8> Uses;

  // Uses that the result of the instruction can reach.
  SmallVector<MachineOperand*, 8> ExtendedUses;

  bool ExtendLife = true;
  UI = MRI->use_nodbg_begin(SrcReg);
  for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end();
       UI != UE; ++UI) {
    MachineOperand &UseMO = UI.getOperand();
    MachineInstr *UseMI = &*UI;
    if (UseMI == MI)
      continue;

    if (UseMI->isPHI()) {
      ExtendLife = false;
      continue;
    }

    // It's an error to translate this:
    //
    //    %reg1025 = <sext> %reg1024
    //     ...
    //    %reg1026 = SUBREG_TO_REG 0, %reg1024, 4
    //
    // into this:
    //
    //    %reg1025 = <sext> %reg1024
    //     ...
    //    %reg1027 = COPY %reg1025:4
    //    %reg1026 = SUBREG_TO_REG 0, %reg1027, 4
    //
    // The problem here is that SUBREG_TO_REG is there to assert that an
    // implicit zext occurs. It doesn't insert a zext instruction. If we allow
    // the COPY here, it will give us the value after the <sext>, not the
    // original value of %reg1024 before <sext>.
    if (UseMI->getOpcode() == TargetOpcode::SUBREG_TO_REG)
      continue;

    MachineBasicBlock *UseMBB = UseMI->getParent();
    if (UseMBB == MBB) {
      // Local uses that come after the extension.
      if (!LocalMIs.count(UseMI))
        Uses.push_back(&UseMO);
    } else if (ReachedBBs.count(UseMBB)) {
      // Non-local uses where the result of the extension is used. Always
      // replace these unless it's a PHI.
      Uses.push_back(&UseMO);
    } else if (Aggressive && DT->dominates(MBB, UseMBB)) {
      // We may want to extend the live range of the extension result in order
      // to replace these uses.
      ExtendedUses.push_back(&UseMO);
    } else {
      // Both will be live out of the def MBB anyway. Don't extend live range of
      // the extension result.
      ExtendLife = false;
      break;
    }
  }

  if (ExtendLife && !ExtendedUses.empty())
    // Extend the liveness of the extension result.
    std::copy(ExtendedUses.begin(), ExtendedUses.end(),
              std::back_inserter(Uses));

  // Now replace all uses.
//.........这里部分代码省略.........

/// DetermineInsertionPoint - At this point, we're committed to promoting the
/// alloca using IDF's, and the standard SSA construction algorithm.  Determine
/// which blocks need phi nodes and see if we can optimize out some work by
/// avoiding insertion of dead phi nodes.
void PromoteMem2Reg::DetermineInsertionPoint(AllocaInst *AI, unsigned AllocaNum,
                                             AllocaInfo &Info) {
  // Unique the set of defining blocks for efficient lookup.
  SmallPtrSet<BasicBlock*, 32> DefBlocks;
  DefBlocks.insert(Info.DefiningBlocks.begin(), Info.DefiningBlocks.end());

  // Determine which blocks the value is live in.  These are blocks which lead
  // to uses.
  SmallPtrSet<BasicBlock*, 32> LiveInBlocks;
  ComputeLiveInBlocks(AI, Info, DefBlocks, LiveInBlocks);

  // Use a priority queue keyed on dominator tree level so that inserted nodes
  // are handled from the bottom of the dominator tree upwards.
  typedef std::priority_queue<DomTreeNodePair, SmallVector<DomTreeNodePair, 32>,
                              DomTreeNodeCompare> IDFPriorityQueue;
  IDFPriorityQueue PQ;

  for (SmallPtrSet<BasicBlock*, 32>::const_iterator I = DefBlocks.begin(),
       E = DefBlocks.end(); I != E; ++I) {
    if (DomTreeNode *Node = DT.getNode(*I))
      PQ.push(std::make_pair(Node, DomLevels[Node]));
  }

  SmallVector<std::pair<unsigned, BasicBlock*>, 32> DFBlocks;
  SmallPtrSet<DomTreeNode*, 32> Visited;
  SmallVector<DomTreeNode*, 32> Worklist;
  while (!PQ.empty()) {
    DomTreeNodePair RootPair = PQ.top();
    PQ.pop();
    DomTreeNode *Root = RootPair.first;
    unsigned RootLevel = RootPair.second;

    // Walk all dominator tree children of Root, inspecting their CFG edges with
    // targets elsewhere on the dominator tree. Only targets whose level is at
    // most Root's level are added to the iterated dominance frontier of the
    // definition set.

    Worklist.clear();
    Worklist.push_back(Root);

    while (!Worklist.empty()) {
      DomTreeNode *Node = Worklist.pop_back_val();
      BasicBlock *BB = Node->getBlock();

      for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE;
           ++SI) {
        DomTreeNode *SuccNode = DT.getNode(*SI);

        // Quickly skip all CFG edges that are also dominator tree edges instead
        // of catching them below.
        if (SuccNode->getIDom() == Node)
          continue;

        unsigned SuccLevel = DomLevels[SuccNode];
        if (SuccLevel > RootLevel)
          continue;

        if (!Visited.insert(SuccNode))
          continue;

        BasicBlock *SuccBB = SuccNode->getBlock();
        if (!LiveInBlocks.count(SuccBB))
          continue;

        DFBlocks.push_back(std::make_pair(BBNumbers[SuccBB], SuccBB));
        if (!DefBlocks.count(SuccBB))
          PQ.push(std::make_pair(SuccNode, SuccLevel));
      }

      for (DomTreeNode::iterator CI = Node->begin(), CE = Node->end(); CI != CE;
           ++CI) {
        if (!Visited.count(*CI))
          Worklist.push_back(*CI);
      }
    }
  }

  if (DFBlocks.size() > 1)
    std::sort(DFBlocks.begin(), DFBlocks.end());

  unsigned CurrentVersion = 0;
  for (unsigned i = 0, e = DFBlocks.size(); i != e; ++i)
    QueuePhiNode(DFBlocks[i].second, AllocaNum, CurrentVersion);
}

//.........这里部分代码省略.........
/// runtime-unroll the loop if computing RuntimeTripCount will be expensive and
/// AllowExpensiveTripCount is false.
///
/// The LoopInfo Analysis that is passed will be kept consistent.
///
/// This utility preserves LoopInfo. It will also preserve ScalarEvolution and
/// DominatorTree if they are non-null.
bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force,
                      bool AllowRuntime, bool AllowExpensiveTripCount,
                      unsigned TripMultiple, LoopInfo *LI, ScalarEvolution *SE,
                      DominatorTree *DT, AssumptionCache *AC,
                      bool PreserveLCSSA) {
  BasicBlock *Preheader = L->getLoopPreheader();
  if (!Preheader) {
    DEBUG(dbgs() << "  Can't unroll; loop preheader-insertion failed.\n");
    return false;
  }

  BasicBlock *LatchBlock = L->getLoopLatch();
  if (!LatchBlock) {
    DEBUG(dbgs() << "  Can't unroll; loop exit-block-insertion failed.\n");
    return false;
  }

  // Loops with indirectbr cannot be cloned.
  if (!L->isSafeToClone()) {
    DEBUG(dbgs() << "  Can't unroll; Loop body cannot be cloned.\n");
    return false;
  }

  BasicBlock *Header = L->getHeader();
  BranchInst *BI = dyn_cast<BranchInst>(LatchBlock->getTerminator());

  if (!BI || BI->isUnconditional()) {
    // The loop-rotate pass can be helpful to avoid this in many cases.
    DEBUG(dbgs() <<
             "  Can't unroll; loop not terminated by a conditional branch.\n");
    return false;
  }

  if (Header->hasAddressTaken()) {
    // The loop-rotate pass can be helpful to avoid this in many cases.
    DEBUG(dbgs() <<
          "  Won't unroll loop: address of header block is taken.\n");
    return false;
  }

  if (TripCount != 0)
    DEBUG(dbgs() << "  Trip Count = " << TripCount << "\n");
  if (TripMultiple != 1)
    DEBUG(dbgs() << "  Trip Multiple = " << TripMultiple << "\n");

  // Effectively "DCE" unrolled iterations that are beyond the tripcount
  // and will never be executed.
  if (TripCount != 0 && Count > TripCount)
    Count = TripCount;

  // Don't enter the unroll code if there is nothing to do. This way we don't
  // need to support "partial unrolling by 1".
  if (TripCount == 0 && Count < 2)
    return false;

  assert(Count > 0);
  assert(TripMultiple > 0);
  assert(TripCount == 0 || TripCount % TripMultiple == 0);

  // Are we eliminating the loop control altogether?
  bool CompletelyUnroll = Count == TripCount;
  SmallVector<BasicBlock *, 4> ExitBlocks;
  L->getExitBlocks(ExitBlocks);
  std::vector<BasicBlock*> OriginalLoopBlocks = L->getBlocks();

  // Go through all exits of L and see if there are any phi-nodes there. We just
  // conservatively assume that they're inserted to preserve LCSSA form, which
  // means that complete unrolling might break this form. We need to either fix
  // it in-place after the transformation, or entirely rebuild LCSSA. TODO: For
  // now we just recompute LCSSA for the outer loop, but it should be possible
  // to fix it in-place.
  bool NeedToFixLCSSA = PreserveLCSSA && CompletelyUnroll &&
      std::any_of(ExitBlocks.begin(), ExitBlocks.end(),
                  [&](BasicBlock *BB) { return isa<PHINode>(BB->begin()); });

  // We assume a run-time trip count if the compiler cannot
  // figure out the loop trip count and the unroll-runtime
  // flag is specified.
  bool RuntimeTripCount = (TripCount == 0 && Count > 0 && AllowRuntime);

  // Loops containing convergent instructions must have a count that divides
  // their TripMultiple.
  DEBUG(
      {
        bool HasConvergent = false;
        for (auto &BB : L->blocks())
          for (auto &I : *BB)
            if (auto CS = CallSite(&I))
              HasConvergent |= CS.isConvergent();
        assert((!HasConvergent || TripMultiple % Count == 0) &&
               "Unroll count must divide trip multiple if loop contains a "
               "convergent operation.");
      });

//.........这里部分代码省略.........
        DAG.getNode(ISD::GC_TRANSITION_START, getCurSDLoc(), NodeTys, TSOps);

    Chain = GCTransitionStart.getValue(0);
    Glue = GCTransitionStart.getValue(1);
  }

  // TODO: Currently, all of these operands are being marked as read/write in
  // PrologEpilougeInserter.cpp, we should special case the VMState arguments
  // and flags to be read-only.
  SmallVector<SDValue, 40> Ops;

  // Add the <id> and <numBytes> constants.
  Ops.push_back(DAG.getTargetConstant(ISP.getID(), getCurSDLoc(), MVT::i64));
  Ops.push_back(
      DAG.getTargetConstant(ISP.getNumPatchBytes(), getCurSDLoc(), MVT::i32));

  // Calculate and push starting position of vmstate arguments
  // Get number of arguments incoming directly into call node
  unsigned NumCallRegArgs =
      CallNode->getNumOperands() - (CallHasIncomingGlue ? 4 : 3);
  Ops.push_back(DAG.getTargetConstant(NumCallRegArgs, getCurSDLoc(), MVT::i32));

  // Add call target
  SDValue CallTarget = SDValue(CallNode->getOperand(1).getNode(), 0);
  Ops.push_back(CallTarget);

  // Add call arguments
  // Get position of register mask in the call
  SDNode::op_iterator RegMaskIt;
  if (CallHasIncomingGlue)
    RegMaskIt = CallNode->op_end() - 2;
  else
    RegMaskIt = CallNode->op_end() - 1;
  Ops.insert(Ops.end(), CallNode->op_begin() + 2, RegMaskIt);

  // Add a constant argument for the calling convention
  pushStackMapConstant(Ops, *this, CS.getCallingConv());

  // Add a constant argument for the flags
  uint64_t Flags = ISP.getFlags();
  assert(
      ((Flags & ~(uint64_t)StatepointFlags::MaskAll) == 0)
          && "unknown flag used");
  pushStackMapConstant(Ops, *this, Flags);

  // Insert all vmstate and gcstate arguments
  Ops.insert(Ops.end(), LoweredMetaArgs.begin(), LoweredMetaArgs.end());

  // Add register mask from call node
  Ops.push_back(*RegMaskIt);

  // Add chain
  Ops.push_back(Chain);

  // Same for the glue, but we add it only if original call had it
  if (Glue.getNode())
    Ops.push_back(Glue);

  // Compute return values.  Provide a glue output since we consume one as
  // input.  This allows someone else to chain off us as needed.
  SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);

  SDNode *StatepointMCNode =
      DAG.getMachineNode(TargetOpcode::STATEPOINT, getCurSDLoc(), NodeTys, Ops);

  SDNode *SinkNode = StatepointMCNode;

// A soft instruction can be changed to work in other domains given by mask.
void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
  // Bitmask of available domains for this instruction after taking collapsed
  // operands into account.
  unsigned available = mask;

  // Scan the explicit use operands for incoming domains.
  SmallVector<int, 4> used;
  if (LiveRegs)
    for (unsigned i = mi->getDesc().getNumDefs(),
                  e = mi->getDesc().getNumOperands(); i != e; ++i) {
      MachineOperand &mo = mi->getOperand(i);
      if (!mo.isReg()) continue;
      for (int rx : regIndices(mo.getReg())) {
        DomainValue *dv = LiveRegs[rx].Value;
        if (dv == nullptr)
          continue;
        // Bitmask of domains that dv and available have in common.
        unsigned common = dv->getCommonDomains(available);
        // Is it possible to use this collapsed register for free?
        if (dv->isCollapsed()) {
          // Restrict available domains to the ones in common with the operand.
          // If there are no common domains, we must pay the cross-domain
          // penalty for this operand.
          if (common) available = common;
        } else if (common)
          // Open DomainValue is compatible, save it for merging.
          used.push_back(rx);
        else
          // Open DomainValue is not compatible with instruction. It is useless
          // now.
          kill(rx);
      }
    }

  // If the collapsed operands force a single domain, propagate the collapse.
  if (isPowerOf2_32(available)) {
    unsigned domain = countTrailingZeros(available);
    TII->setExecutionDomain(*mi, domain);
    visitHardInstr(mi, domain);
    return;
  }

  // Kill off any remaining uses that don't match available, and build a list of
  // incoming DomainValues that we want to merge.
  SmallVector<LiveReg, 4> Regs;
  for (SmallVectorImpl<int>::iterator i=used.begin(), e=used.end(); i!=e; ++i) {
    int rx = *i;
    assert(LiveRegs && "no space allocated for live registers");
    const LiveReg &LR = LiveRegs[rx];
    // This useless DomainValue could have been missed above.
    if (!LR.Value->getCommonDomains(available)) {
      kill(rx);
      continue;
    }
    // Sorted insertion.
    bool Inserted = false;
    for (SmallVectorImpl<LiveReg>::iterator i = Regs.begin(), e = Regs.end();
           i != e && !Inserted; ++i) {
      if (LR.Def < i->Def) {
        Inserted = true;
        Regs.insert(i, LR);
      }
    }
    if (!Inserted)
      Regs.push_back(LR);
  }

  // doms are now sorted in order of appearance. Try to merge them all, giving
  // priority to the latest ones.
  DomainValue *dv = nullptr;
  while (!Regs.empty()) {
    if (!dv) {
      dv = Regs.pop_back_val().Value;
      // Force the first dv to match the current instruction.
      dv->AvailableDomains = dv->getCommonDomains(available);
      assert(dv->AvailableDomains && "Domain should have been filtered");
      continue;
    }

    DomainValue *Latest = Regs.pop_back_val().Value;
    // Skip already merged values.
    if (Latest == dv || Latest->Next)
      continue;
    if (merge(dv, Latest))
      continue;

    // If latest didn't merge, it is useless now. Kill all registers using it.
    for (int i : used) {
      assert(LiveRegs && "no space allocated for live registers");
      if (LiveRegs[i].Value == Latest)
        kill(i);
    }
  }

  // dv is the DomainValue we are going to use for this instruction.
  if (!dv) {
    dv = alloc();
    dv->AvailableDomains = available;
  }
//.........这里部分代码省略.........