C++ SmallVector类代码示例

SDValue MSP430TargetLowering::LowerSETCC(SDValue Op, SelectionDAG &DAG) const {
  SDValue LHS   = Op.getOperand(0);
  SDValue RHS   = Op.getOperand(1);
  DebugLoc dl   = Op.getDebugLoc();

  // If we are doing an AND and testing against zero, then the CMP
  // will not be generated.  The AND (or BIT) will generate the condition codes,
  // but they are different from CMP.
  // FIXME: since we're doing a post-processing, use a pseudoinstr here, so
  // lowering & isel wouldn't diverge.
  bool andCC = false;
  if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(RHS)) {
    if (RHSC->isNullValue() && LHS.hasOneUse() &&
        (LHS.getOpcode() == ISD::AND ||
         (LHS.getOpcode() == ISD::TRUNCATE &&
          LHS.getOperand(0).getOpcode() == ISD::AND))) {
      andCC = true;
    }
  }
  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(2))->get();
  SDValue TargetCC;
  SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);

  // Get the condition codes directly from the status register, if its easy.
  // Otherwise a branch will be generated.  Note that the AND and BIT
  // instructions generate different flags than CMP, the carry bit can be used
  // for NE/EQ.
  bool Invert = false;
  bool Shift = false;
  bool Convert = true;
  switch (cast<ConstantSDNode>(TargetCC)->getZExtValue()) {
   default:
    Convert = false;
    break;
   case MSP430CC::COND_HS:
     // Res = SRW & 1, no processing is required
     break;
   case MSP430CC::COND_LO:
     // Res = ~(SRW & 1)
     Invert = true;
     break;
   case MSP430CC::COND_NE:
     if (andCC) {
       // C = ~Z, thus Res = SRW & 1, no processing is required
     } else {
       // Res = ~((SRW >> 1) & 1)
       Shift = true;
       Invert = true;
     }
     break;
   case MSP430CC::COND_E:
     Shift = true;
     // C = ~Z for AND instruction, thus we can put Res = ~(SRW & 1), however,
     // Res = (SRW >> 1) & 1 is 1 word shorter.
     break;
  }
  EVT VT = Op.getValueType();
  SDValue One  = DAG.getConstant(1, VT);
  if (Convert) {
    SDValue SR = DAG.getCopyFromReg(DAG.getEntryNode(), dl, MSP430::SRW,
                                    MVT::i16, Flag);
    if (Shift)
      // FIXME: somewhere this is turned into a SRL, lower it MSP specific?
      SR = DAG.getNode(ISD::SRA, dl, MVT::i16, SR, One);
    SR = DAG.getNode(ISD::AND, dl, MVT::i16, SR, One);
    if (Invert)
      SR = DAG.getNode(ISD::XOR, dl, MVT::i16, SR, One);
    return SR;
  } else {
    SDValue Zero = DAG.getConstant(0, VT);
    SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue);
    SmallVector<SDValue, 4> Ops;
    Ops.push_back(One);
    Ops.push_back(Zero);
    Ops.push_back(TargetCC);
    Ops.push_back(Flag);
    return DAG.getNode(MSP430ISD::SELECT_CC, dl, VTs, &Ops[0], Ops.size());
  }
}

llvm::Constant *
CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD,
                                        const VTableComponent *Components, 
                                        unsigned NumComponents,
                                const VTableLayout::VTableThunkTy *VTableThunks,
                                        unsigned NumVTableThunks) {
  SmallVector<llvm::Constant *, 64> Inits;

  llvm::Type *Int8PtrTy = CGM.Int8PtrTy;
  
  llvm::Type *PtrDiffTy = 
    CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());

  QualType ClassType = CGM.getContext().getTagDeclType(RD);
  llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor(ClassType);
  
  unsigned NextVTableThunkIndex = 0;
  
  llvm::Constant* PureVirtualFn = 0;

  for (unsigned I = 0; I != NumComponents; ++I) {
    VTableComponent Component = Components[I];

    llvm::Constant *Init = 0;

    switch (Component.getKind()) {
    case VTableComponent::CK_VCallOffset:
      Init = llvm::ConstantInt::get(PtrDiffTy, 
                                    Component.getVCallOffset().getQuantity());
      Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
      break;
    case VTableComponent::CK_VBaseOffset:
      Init = llvm::ConstantInt::get(PtrDiffTy, 
                                    Component.getVBaseOffset().getQuantity());
      Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
      break;
    case VTableComponent::CK_OffsetToTop:
      Init = llvm::ConstantInt::get(PtrDiffTy, 
                                    Component.getOffsetToTop().getQuantity());
      Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
      break;
    case VTableComponent::CK_RTTI:
      Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy);
      break;
    case VTableComponent::CK_FunctionPointer:
    case VTableComponent::CK_CompleteDtorPointer:
    case VTableComponent::CK_DeletingDtorPointer: {
      GlobalDecl GD;
      
      // Get the right global decl.
      switch (Component.getKind()) {
      default:
        llvm_unreachable("Unexpected vtable component kind");
      case VTableComponent::CK_FunctionPointer:
        GD = Component.getFunctionDecl();
        break;
      case VTableComponent::CK_CompleteDtorPointer:
        GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Complete);
        break;
      case VTableComponent::CK_DeletingDtorPointer:
        GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Deleting);
        break;
      }

      if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) {
        // We have a pure virtual member function.
        if (!PureVirtualFn) {
          llvm::FunctionType *Ty = 
            llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
          StringRef PureCallName = CGM.getCXXABI().GetPureVirtualCallName();
          PureVirtualFn = CGM.CreateRuntimeFunction(Ty, PureCallName);
          PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn,
                                                         CGM.Int8PtrTy);
        }
        Init = PureVirtualFn;
      } else {
        // Check if we should use a thunk.
        if (NextVTableThunkIndex < NumVTableThunks &&
            VTableThunks[NextVTableThunkIndex].first == I) {
          const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second;
        
          MaybeEmitThunkAvailableExternally(GD, Thunk);
          Init = CGM.GetAddrOfThunk(GD, Thunk);

          NextVTableThunkIndex++;
        } else {
          llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD);
        
          Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
        }

        Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy);
      }
      break;
    }

    case VTableComponent::CK_UnusedFunctionPointer:
      Init = llvm::ConstantExpr::getNullValue(Int8PtrTy);
      break;
    };
//.........这里部分代码省略.........

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

  // Emit the indirect return argument, if any.
  SILValue resultSlot;
  if (selfTy.isAddressOnly(SGF.SGM.M) && SGF.silConv.useLoweredAddresses()) {
    auto &AC = SGF.getASTContext();
    auto VD = new (AC) ParamDecl(VarDecl::Specifier::InOut,
                                 SourceLoc(), SourceLoc(),
                                 AC.getIdentifier("$return_value"),
                                 SourceLoc(),
                                 AC.getIdentifier("$return_value"),
                                 ctor);
    VD->setInterfaceType(selfIfaceTyCan);
    resultSlot = SGF.F.begin()->createFunctionArgument(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(
          SGF, Loc, param->getInterfaceType()->getCanonicalType(), ctor));
  }

  emitConstructorMetatypeArg(SGF, 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, SGF.SGM.M);
      auto &fieldTL = SGF.getTypeLowering(fieldTy);
      SILValue slot = SGF.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()) {
#ifndef NDEBUG
        auto fieldTy = decl->getDeclContext()->mapTypeIntoContext(
            field->getInterfaceType());
        assert(fieldTy->isEqual(field->getParentInitializer()->getType())
               && "Checked by sema");
#endif

        // Cleanup after this initialization.
        FullExpr scope(SGF.Cleanups, field->getParentPatternBinding());
        SGF.emitExprInto(field->getParentInitializer(), init.get());
        continue;
      }

      assert(elti != eltEnd && "number of args does not match number of fields");
      (void)eltEnd;
      std::move(*elti).forwardInto(SGF, Loc, init.get());
      ++elti;
    }
    SGF.B.createReturn(ImplicitReturnLocation::getImplicitReturnLoc(Loc),
                       SGF.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, SGF.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(SGF.Cleanups, field->getParentPatternBinding());
      v = SGF.emitRValue(field->getParentInitializer())
             .forwardAsSingleStorageValue(SGF, fieldTy, Loc);
    } else {
      assert(elti != eltEnd && "number of args does not match number of fields");
      (void)eltEnd;
      v = std::move(*elti).forwardAsSingleStorageValue(SGF, fieldTy, Loc);
      ++elti;
    }

//.........这里部分代码省略.........

//.........这里部分代码省略.........
  // Virt is the block containing the slow virtual call.
  SILBasicBlock *Virt = F->createBasicBlock();
  Iden->createBBArg(SubType);

  SILBasicBlock *Continue = Entry->splitBasicBlock(It);

  SILBuilderWithScope Builder(Entry, AI.getInstruction());
  // Create the checked_cast_branch instruction that checks at runtime if the
  // class instance is identical to the SILType.

  ClassMethodInst *CMI = cast<ClassMethodInst>(AI.getCallee());

  CCBI = Builder.createCheckedCastBranch(AI.getLoc(), /*exact*/ true,
                                       CMI->getOperand(), SubType, Iden,
                                       Virt);
  It = CCBI->getIterator();

  SILBuilderWithScope VirtBuilder(Virt, AI.getInstruction());
  SILBuilderWithScope IdenBuilder(Iden, AI.getInstruction());
  // This is the class reference downcasted into subclass SubType.
  SILValue DownCastedClassInstance = Iden->getBBArg(0);

  // Copy the two apply instructions into the two blocks.
  FullApplySite IdenAI = CloneApply(AI, IdenBuilder);
  FullApplySite VirtAI = CloneApply(AI, VirtBuilder);

  // See if Continue has a release on self as the instruction right after the
  // apply. If it exists, move it into position in the diamond.
  if (auto *Release =
          dyn_cast<StrongReleaseInst>(std::next(Continue->begin()))) {
    if (Release->getOperand() == CMI->getOperand()) {
      VirtBuilder.createStrongRelease(Release->getLoc(), CMI->getOperand(),
                                      Atomicity::Atomic);
      IdenBuilder.createStrongRelease(
          Release->getLoc(), DownCastedClassInstance, Atomicity::Atomic);
      Release->eraseFromParent();
    }
  }

  // Create a PHInode for returning the return value from both apply
  // instructions.
  SILArgument *Arg = Continue->createBBArg(AI.getType());
  if (!isa<TryApplyInst>(AI)) {
    IdenBuilder.createBranch(AI.getLoc(), Continue,
                             ArrayRef<SILValue>(IdenAI.getInstruction()));
    VirtBuilder.createBranch(AI.getLoc(), Continue,
                             ArrayRef<SILValue>(VirtAI.getInstruction()));
  }

  // Remove the old Apply instruction.
  assert(AI.getInstruction() == &Continue->front() &&
         "AI should be the first instruction in the split Continue block");
  if (!isa<TryApplyInst>(AI)) {
    AI.getInstruction()->replaceAllUsesWith(Arg);
    AI.getInstruction()->eraseFromParent();
    assert(!Continue->empty() &&
           "There should be at least a terminator after AI");
  } else {
    AI.getInstruction()->eraseFromParent();
    assert(Continue->empty() &&
           "There should not be an instruction after try_apply");
    Continue->eraseFromParent();
  }

  // Update the stats.
  NumTargetsPredicted++;

  // Devirtualize the apply instruction on the identical path.
  auto NewInstPair = devirtualizeClassMethod(IdenAI, DownCastedClassInstance);
  assert(NewInstPair.first && "Expected to be able to devirtualize apply!");
  replaceDeadApply(IdenAI, NewInstPair.first);

  // Split critical edges resulting from VirtAI.
  if (auto *TAI = dyn_cast<TryApplyInst>(VirtAI)) {
    auto *ErrorBB = TAI->getFunction()->createBasicBlock();
    ErrorBB->createBBArg(TAI->getErrorBB()->getBBArg(0)->getType());
    Builder.setInsertionPoint(ErrorBB);
    Builder.createBranch(TAI->getLoc(), TAI->getErrorBB(),
                         {ErrorBB->getBBArg(0)});

    auto *NormalBB = TAI->getFunction()->createBasicBlock();
    NormalBB->createBBArg(TAI->getNormalBB()->getBBArg(0)->getType());
    Builder.setInsertionPoint(NormalBB);
    Builder.createBranch(TAI->getLoc(), TAI->getNormalBB(),
                        {NormalBB->getBBArg(0) });

    Builder.setInsertionPoint(VirtAI.getInstruction());
    SmallVector<SILValue, 4> Args;
    for (auto Arg : VirtAI.getArguments()) {
      Args.push_back(Arg);
    }
    FullApplySite NewVirtAI = Builder.createTryApply(VirtAI.getLoc(), VirtAI.getCallee(),
        VirtAI.getSubstCalleeSILType(), VirtAI.getSubstitutions(),
        Args, NormalBB, ErrorBB);
    VirtAI.getInstruction()->eraseFromParent();
    VirtAI = NewVirtAI;
  }

  return VirtAI;
}

/// 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);
}

/// VerifyIndirectJumps - Verify whether any possible indirect jump
/// might cross a protection boundary.  Unlike direct jumps, indirect
/// jumps count cleanups as protection boundaries:  since there's no
/// way to know where the jump is going, we can't implicitly run the
/// right cleanups the way we can with direct jumps.
///
/// Thus, an indirect jump is "trivial" if it bypasses no
/// initializations and no teardowns.  More formally, an indirect jump
/// from A to B is trivial if the path out from A to DCA(A,B) is
/// trivial and the path in from DCA(A,B) to B is trivial, where
/// DCA(A,B) is the deepest common ancestor of A and B.
/// Jump-triviality is transitive but asymmetric.
///
/// A path in is trivial if none of the entered scopes have an InDiag.
/// A path out is trivial is none of the exited scopes have an OutDiag.
///
/// Under these definitions, this function checks that the indirect
/// jump between A and B is trivial for every indirect goto statement A
/// and every label B whose address was taken in the function.
void JumpScopeChecker::VerifyIndirectJumps() {
  if (IndirectJumps.empty()) return;

  // If there aren't any address-of-label expressions in this function,
  // complain about the first indirect goto.
  if (IndirectJumpTargets.empty()) {
    S.Diag(IndirectJumps[0]->getGotoLoc(),
           diag::err_indirect_goto_without_addrlabel);
    return;
  }

  // Collect a single representative of every scope containing an
  // indirect goto.  For most code bases, this substantially cuts
  // down on the number of jump sites we'll have to consider later.
  typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope;
  SmallVector<JumpScope, 32> JumpScopes;
  {
    llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap;
    for (SmallVectorImpl<IndirectGotoStmt*>::iterator
           I = IndirectJumps.begin(), E = IndirectJumps.end(); I != E; ++I) {
      IndirectGotoStmt *IG = *I;
      assert(LabelAndGotoScopes.count(IG) &&
             "indirect jump didn't get added to scopes?");
      unsigned IGScope = LabelAndGotoScopes[IG];
      IndirectGotoStmt *&Entry = JumpScopesMap[IGScope];
      if (!Entry) Entry = IG;
    }
    JumpScopes.reserve(JumpScopesMap.size());
    for (llvm::DenseMap<unsigned, IndirectGotoStmt*>::iterator
           I = JumpScopesMap.begin(), E = JumpScopesMap.end(); I != E; ++I)
      JumpScopes.push_back(*I);
  }

  // Collect a single representative of every scope containing a
  // label whose address was taken somewhere in the function.
  // For most code bases, there will be only one such scope.
  llvm::DenseMap<unsigned, LabelDecl*> TargetScopes;
  for (SmallVectorImpl<LabelDecl*>::iterator
         I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end();
       I != E; ++I) {
    LabelDecl *TheLabel = *I;
    assert(LabelAndGotoScopes.count(TheLabel->getStmt()) &&
           "Referenced label didn't get added to scopes?");
    unsigned LabelScope = LabelAndGotoScopes[TheLabel->getStmt()];
    LabelDecl *&Target = TargetScopes[LabelScope];
    if (!Target) Target = TheLabel;
  }

  // For each target scope, make sure it's trivially reachable from
  // every scope containing a jump site.
  //
  // A path between scopes always consists of exitting zero or more
  // scopes, then entering zero or more scopes.  We build a set of
  // of scopes S from which the target scope can be trivially
  // entered, then verify that every jump scope can be trivially
  // exitted to reach a scope in S.
  llvm::BitVector Reachable(Scopes.size(), false);
  for (llvm::DenseMap<unsigned,LabelDecl*>::iterator
         TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) {
    unsigned TargetScope = TI->first;
    LabelDecl *TargetLabel = TI->second;

    Reachable.reset();

    // Mark all the enclosing scopes from which you can safely jump
    // into the target scope.  'Min' will end up being the index of
    // the shallowest such scope.
    unsigned Min = TargetScope;
    while (true) {
      Reachable.set(Min);

      // Don't go beyond the outermost scope.
      if (Min == 0) break;

      // Stop if we can't trivially enter the current scope.
      if (Scopes[Min].InDiag) break;

      Min = Scopes[Min].ParentScope;
    }

    // Walk through all the jump sites, checking that they can trivially
//.........这里部分代码省略.........

/// \brief Collect the set of header includes needed to construct the given 
/// module and update the TopHeaders file set of the module.
///
/// \param Module The module we're collecting includes from.
///
/// \param Includes Will be augmented with the set of \#includes or \#imports
/// needed to load all of the named headers.
static std::error_code
collectModuleHeaderIncludes(const LangOptions &LangOpts, FileManager &FileMgr,
                            ModuleMap &ModMap, clang::Module *Module,
                            SmallVectorImpl<char> &Includes) {
  // Don't collect any headers for unavailable modules.
  if (!Module->isAvailable())
    return std::error_code();

  // Add includes for each of these headers.
  for (Module::Header &H : Module->Headers[Module::HK_Normal]) {
    Module->addTopHeader(H.Entry);
    // Use the path as specified in the module map file. We'll look for this
    // file relative to the module build directory (the directory containing
    // the module map file) so this will find the same file that we found
    // while parsing the module map.
    if (std::error_code Err = addHeaderInclude(H.NameAsWritten, Includes,
                                               LangOpts, Module->IsExternC))
      return Err;
  }
  // Note that Module->PrivateHeaders will not be a TopHeader.

  if (Module::Header UmbrellaHeader = Module->getUmbrellaHeader()) {
    Module->addTopHeader(UmbrellaHeader.Entry);
    if (Module->Parent) {
      // Include the umbrella header for submodules.
      if (std::error_code Err = addHeaderInclude(UmbrellaHeader.NameAsWritten,
                                                 Includes, LangOpts,
                                                 Module->IsExternC))
        return Err;
    }
  } else if (Module::DirectoryName UmbrellaDir = Module->getUmbrellaDir()) {
    // Add all of the headers we find in this subdirectory.
    std::error_code EC;
    SmallString<128> DirNative;
    llvm::sys::path::native(UmbrellaDir.Entry->getName(), DirNative);
    for (llvm::sys::fs::recursive_directory_iterator Dir(DirNative, EC), 
                                                     DirEnd;
         Dir != DirEnd && !EC; Dir.increment(EC)) {
      // Check whether this entry has an extension typically associated with 
      // headers.
      if (!llvm::StringSwitch<bool>(llvm::sys::path::extension(Dir->path()))
          .Cases(".h", ".H", ".hh", ".hpp", true)
          .Default(false))
        continue;

      const FileEntry *Header = FileMgr.getFile(Dir->path());
      // FIXME: This shouldn't happen unless there is a file system race. Is
      // that worth diagnosing?
      if (!Header)
        continue;

      // If this header is marked 'unavailable' in this module, don't include 
      // it.
      if (ModMap.isHeaderUnavailableInModule(Header, Module))
        continue;

      // Compute the relative path from the directory to this file.
      SmallVector<StringRef, 16> Components;
      auto PathIt = llvm::sys::path::rbegin(Dir->path());
      for (int I = 0; I != Dir.level() + 1; ++I, ++PathIt)
        Components.push_back(*PathIt);
      SmallString<128> RelativeHeader(UmbrellaDir.NameAsWritten);
      for (auto It = Components.rbegin(), End = Components.rend(); It != End;
           ++It)
        llvm::sys::path::append(RelativeHeader, *It);

      // Include this header as part of the umbrella directory.
      Module->addTopHeader(Header);
      if (std::error_code Err = addHeaderInclude(RelativeHeader, Includes,
                                                 LangOpts, Module->IsExternC))
        return Err;
    }

    if (EC)
      return EC;
  }

  // Recurse into submodules.
  for (clang::Module::submodule_iterator Sub = Module->submodule_begin(),
                                      SubEnd = Module->submodule_end();
       Sub != SubEnd; ++Sub)
    if (std::error_code Err = collectModuleHeaderIncludes(
            LangOpts, FileMgr, ModMap, *Sub, Includes))
      return Err;

  return std::error_code();
}

CallGraphNode* ArgumentRecovery::recoverArguments(llvm::CallGraphNode *node)
{
	Function* fn = node->getFunction();
	if (fn == nullptr)
	{
		// "theoretical nodes", whatever that is
		return nullptr;
	}
	
	// quick exit if there isn't exactly one argument
	if (fn->arg_size() != 1)
	{
		return nullptr;
	}
	
	Argument* fnArg = fn->arg_begin();
	if (!isStructType(fnArg))
	{
		return nullptr;
	}
	
	// This is a nasty NASTY hack that relies on the AA pass being RegisterUse.
	// The data should be moved to a separate helper pass that can be queried from both the AA pass and this one.
	RegisterUse& regUse = getAnalysis<RegisterUse>();
	CallGraph& cg = getAnalysis<CallGraphWrapperPass>().getCallGraph();
	
	const auto* modRefInfo = regUse.getModRefInfo(fn);
	assert(modRefInfo != nullptr);
	
	// At this point we pretty much know that we're going to modify the function, so start doing that.
	// Get register offsets from the old function before we start mutilating it.
	auto& registerMap = exposeAllRegisters(fn);
	
	// Create a new function prototype, asking RegisterUse for which registers should be passed in, and how.
	
	LLVMContext& ctx = fn->getContext();
	SmallVector<pair<const char*, Type*>, 16> parameters;
	Type* int64 = Type::getInt64Ty(ctx);
	Type* int64ptr = Type::getInt64PtrTy(ctx);
	for (const auto& pair : *modRefInfo)
	{
		if (pair.second != RegisterUse::NoModRef)
		{
			Type* paramType = (pair.second & RegisterUse::Mod) == RegisterUse::Mod ? int64ptr : int64;
			parameters.push_back({pair.first, paramType});
		}
	}
	
	// Order parameters.
	// FIXME: This could use an ABI-specific sort routine. For now, use a lexicographical sort.
	sort(parameters.begin(), parameters.end(), [](const pair<const char*, Type*>& a, const pair<const char*, Type*>& b) {
		return strcmp(a.first, b.first) < 0;
	});
	
	// Extract parameter types.
	SmallVector<Type*, 16> parameterTypes;
	for (const auto& pair : parameters)
	{
		parameterTypes.push_back(pair.second);
	}
	
	// Ideally, we would also do caller analysis here to figure out which output registers are never read, such that
	// we can either eliminate them from the parameter list or pass them by value instead of by address.
	// We would also pick a return value.
	FunctionType* newFunctionType = FunctionType::get(Type::getVoidTy(ctx), parameterTypes, false);

	Function* newFunc = Function::Create(newFunctionType, fn->getLinkage());
	newFunc->copyAttributesFrom(fn);
	fn->getParent()->getFunctionList().insert(fn, newFunc);
	newFunc->takeName(fn);
	fn->setName("__hollow_husk__" + newFunc->getName());
	
	// Set argument names
	size_t i = 0;
	
	for (Argument& arg : newFunc->args())
	{
		arg.setName(parameters[i].first);
		i++;
	}
	
	// update call graph
	CallGraphNode* newFuncNode = cg.getOrInsertFunction(newFunc);
	CallGraphNode* oldFuncNode = cg[fn];
	
	// loop over callers and transform call sites.
	while (!fn->use_empty())
	{
		CallSite cs(fn->user_back());
		Instruction* call = cast<CallInst>(cs.getInstruction());
		Function* caller = call->getParent()->getParent();
		
		auto& registerPositions = exposeAllRegisters(caller);
		SmallVector<Value*, 16> callParameters;
		for (const auto& pair : parameters)
		{
			// HACKHACK: find a pointer to a 64-bit int in the set.
			Value* registerPointer = nullptr;
			auto range = registerPositions.equal_range(pair.first);
			for (auto iter = range.first; iter != range.second; iter++)
//.........这里部分代码省略.........

void StackAllocationPromoter::fixBranchesAndUses(BlockSet &PhiBlocks) {
  // First update uses of the value.
  SmallVector<LoadInst *, 4> collectedLoads;
  for (auto UI = ASI->use_begin(), E = ASI->use_end(); UI != E;) {
    auto *Inst = UI->getUser();
    UI++;
    bool removedUser = false;

    collectedLoads.clear();
    collectLoads(Inst, collectedLoads);
    for (LoadInst *LI : collectedLoads) {
      SILValue Def;
      // If this block has no predecessors then nothing dominates it and
      // the instruction is unreachable. If the instruction we're
      // examining is a value, replace it with undef. Either way, delete
      // the instruction and move on.
      SILBasicBlock *BB = LI->getParent();
      Def = getLiveInValue(PhiBlocks, BB);

      LLVM_DEBUG(llvm::dbgs() << "*** Replacing " << *LI
                              << " with Def " << *Def);

      // Replace the load with the definition that we found.
      replaceLoad(LI, Def, ASI);
      removedUser = true;
      NumInstRemoved++;
    }

    if (removedUser)
      continue;

    // If this block has no predecessors then nothing dominates it and
    // the instruction is unreachable. Delete the instruction and move
    // on.
    SILBasicBlock *BB = Inst->getParent();

    if (auto *DVAI = dyn_cast<DebugValueAddrInst>(Inst)) {
      // Replace DebugValueAddr with DebugValue.
      SILValue Def = getLiveInValue(PhiBlocks, BB);
      promoteDebugValueAddr(DVAI, Def, B);
      NumInstRemoved++;
      continue;
    }

    // Replace destroys with a release of the value.
    if (auto *DAI = dyn_cast<DestroyAddrInst>(Inst)) {
      SILValue Def = getLiveInValue(PhiBlocks, BB);
      replaceDestroy(DAI, Def);
      continue;
    }
  }

  // Now that all of the uses are fixed we can fix the branches that point
  // to the blocks with the added arguments.

  // For each Block with a new Phi argument:
  for (auto Block : PhiBlocks) {
    // Fix all predecessors.
    for (auto PBBI = Block->getPredecessorBlocks().begin(),
              E = Block->getPredecessorBlocks().end();
         PBBI != E;) {
      auto *PBB = *PBBI;
      ++PBBI;
      assert(PBB && "Invalid block!");
      fixPhiPredBlock(PhiBlocks, Block, PBB);
    }
  }
}

/// InlineFunction - This function inlines the called function into the basic
/// block of the caller.  This returns false if it is not possible to inline
/// this call.  The program is still in a well defined state if this occurs
/// though.
///
/// Note that this only does one level of inlining.  For example, if the
/// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
/// exists in the instruction stream.  Similarly this will inline a recursive
/// function by one level.
bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
                          bool InsertLifetime) {
    Instruction *TheCall = CS.getInstruction();
    assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
           "Instruction not in function!");

    // If IFI has any state in it, zap it before we fill it in.
    IFI.reset();

    const Function *CalledFunc = CS.getCalledFunction();
    if (CalledFunc == 0 ||          // Can't inline external function or indirect
            CalledFunc->isDeclaration() || // call, or call to a vararg function!
            CalledFunc->getFunctionType()->isVarArg()) return false;

    // If the call to the callee is not a tail call, we must clear the 'tail'
    // flags on any calls that we inline.
    bool MustClearTailCallFlags =
        !(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall());

    // If the call to the callee cannot throw, set the 'nounwind' flag on any
    // calls that we inline.
    bool MarkNoUnwind = CS.doesNotThrow();

    BasicBlock *OrigBB = TheCall->getParent();
    Function *Caller = OrigBB->getParent();

    // GC poses two hazards to inlining, which only occur when the callee has GC:
    //  1. If the caller has no GC, then the callee's GC must be propagated to the
    //     caller.
    //  2. If the caller has a differing GC, it is invalid to inline.
    if (CalledFunc->hasGC()) {
        if (!Caller->hasGC())
            Caller->setGC(CalledFunc->getGC());
        else if (CalledFunc->getGC() != Caller->getGC())
            return false;
    }

    // Get the personality function from the callee if it contains a landing pad.
    Value *CalleePersonality = 0;
    for (Function::const_iterator I = CalledFunc->begin(), E = CalledFunc->end();
            I != E; ++I)
        if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
            const BasicBlock *BB = II->getUnwindDest();
            const LandingPadInst *LP = BB->getLandingPadInst();
            CalleePersonality = LP->getPersonalityFn();
            break;
        }

    // Find the personality function used by the landing pads of the caller. If it
    // exists, then check to see that it matches the personality function used in
    // the callee.
    if (CalleePersonality) {
        for (Function::const_iterator I = Caller->begin(), E = Caller->end();
                I != E; ++I)
            if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
                const BasicBlock *BB = II->getUnwindDest();
                const LandingPadInst *LP = BB->getLandingPadInst();

                // If the personality functions match, then we can perform the
                // inlining. Otherwise, we can't inline.
                // TODO: This isn't 100% true. Some personality functions are proper
                //       supersets of others and can be used in place of the other.
                if (LP->getPersonalityFn() != CalleePersonality)
                    return false;

                break;
            }
    }

    // Get an iterator to the last basic block in the function, which will have
    // the new function inlined after it.
    Function::iterator LastBlock = &Caller->back();

    // Make sure to capture all of the return instructions from the cloned
    // function.
    SmallVector<ReturnInst*, 8> Returns;
    ClonedCodeInfo InlinedFunctionInfo;
    Function::iterator FirstNewBlock;

    {   // Scope to destroy VMap after cloning.
        ValueToValueMapTy VMap;

        assert(CalledFunc->arg_size() == CS.arg_size() &&
               "No varargs calls can be inlined!");

        // Calculate the vector of arguments to pass into the function cloner, which
        // matches up the formal to the actual argument values.
        CallSite::arg_iterator AI = CS.arg_begin();
        unsigned ArgNo = 0;
        for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
                E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
//.........这里部分代码省略.........

std::string Triple::normalize(StringRef Str) {
  // Parse into components.
  SmallVector<StringRef, 4> Components;
  Str.split(Components, "-");

  // If the first component corresponds to a known architecture, preferentially
  // use it for the architecture.  If the second component corresponds to a
  // known vendor, preferentially use it for the vendor, etc.  This avoids silly
  // component movement when a component parses as (eg) both a valid arch and a
  // valid os.
  ArchType Arch = UnknownArch;
  if (Components.size() > 0)
    Arch = parseArch(Components[0]);
  VendorType Vendor = UnknownVendor;
  if (Components.size() > 1)
    Vendor = parseVendor(Components[1]);
  OSType OS = UnknownOS;
  if (Components.size() > 2)
    OS = parseOS(Components[2]);
  EnvironmentType Environment = UnknownEnvironment;
  if (Components.size() > 3)
    Environment = parseEnvironment(Components[3]);
  ObjectFormatType ObjectFormat = UnknownObjectFormat;

  // Note which components are already in their final position.  These will not
  // be moved.
  bool Found[4];
  Found[0] = Arch != UnknownArch;
  Found[1] = Vendor != UnknownVendor;
  Found[2] = OS != UnknownOS;
  Found[3] = Environment != UnknownEnvironment;

  // If they are not there already, permute the components into their canonical
  // positions by seeing if they parse as a valid architecture, and if so moving
  // the component to the architecture position etc.
  for (unsigned Pos = 0; Pos != array_lengthof(Found); ++Pos) {
    if (Found[Pos])
      continue; // Already in the canonical position.

    for (unsigned Idx = 0; Idx != Components.size(); ++Idx) {
      // Do not reparse any components that already matched.
      if (Idx < array_lengthof(Found) && Found[Idx])
        continue;

      // Does this component parse as valid for the target position?
      bool Valid = false;
      StringRef Comp = Components[Idx];
      switch (Pos) {
      default: llvm_unreachable("unexpected component type!");
      case 0:
        Arch = parseArch(Comp);
        Valid = Arch != UnknownArch;
        break;
      case 1:
        Vendor = parseVendor(Comp);
        Valid = Vendor != UnknownVendor;
        break;
      case 2:
        OS = parseOS(Comp);
        Valid = OS != UnknownOS;
        break;
      case 3:
        Environment = parseEnvironment(Comp);
        Valid = Environment != UnknownEnvironment;
        if (!Valid) {
          ObjectFormat = parseFormat(Comp);
          Valid = ObjectFormat != UnknownObjectFormat;
        }
        break;
      }
      if (!Valid)
        continue; // Nope, try the next component.

      // Move the component to the target position, pushing any non-fixed
      // components that are in the way to the right.  This tends to give
      // good results in the common cases of a forgotten vendor component
      // or a wrongly positioned environment.
      if (Pos < Idx) {
        // Insert left, pushing the existing components to the right.  For
        // example, a-b-i386 -> i386-a-b when moving i386 to the front.
        StringRef CurrentComponent(""); // The empty component.
        // Replace the component we are moving with an empty component.
        std::swap(CurrentComponent, Components[Idx]);
        // Insert the component being moved at Pos, displacing any existing
        // components to the right.
        for (unsigned i = Pos; !CurrentComponent.empty(); ++i) {
          // Skip over any fixed components.
          while (i < array_lengthof(Found) && Found[i])
            ++i;
          // Place the component at the new position, getting the component
          // that was at this position - it will be moved right.
          std::swap(CurrentComponent, Components[i]);
        }
      } else if (Pos > Idx) {
        // Push right by inserting empty components until the component at Idx
        // reaches the target position Pos.  For example, pc-a -> -pc-a when
        // moving pc to the second position.
        do {
          // Insert one empty component at Idx.
          StringRef CurrentComponent(""); // The empty component.
//.........这里部分代码省略.........

/// EmitAnyX86InstComments - This function decodes x86 instructions and prints
/// newline terminated strings to the specified string if desired.  This
/// information is shown in disassembly dumps when verbose assembly is enabled.
void llvm::EmitAnyX86InstComments(const MCInst *MI, raw_ostream &OS,
                                  const char *(*getRegName)(unsigned)) {
  // If this is a shuffle operation, the switch should fill in this state.
  SmallVector<int, 8> ShuffleMask;
  const char *DestName = 0, *Src1Name = 0, *Src2Name = 0;

  switch (MI->getOpcode()) {
  case X86::INSERTPSrr:
    Src1Name = getRegName(MI->getOperand(0).getReg());
    Src2Name = getRegName(MI->getOperand(2).getReg());
    DecodeINSERTPSMask(MI->getOperand(3).getImm(), ShuffleMask);
    break;
  case X86::VINSERTPSrr:
    DestName = getRegName(MI->getOperand(0).getReg());
    Src1Name = getRegName(MI->getOperand(1).getReg());
    Src2Name = getRegName(MI->getOperand(2).getReg());
    DecodeINSERTPSMask(MI->getOperand(3).getImm(), ShuffleMask);
    break;

  case X86::MOVLHPSrr:
    Src2Name = getRegName(MI->getOperand(2).getReg());
    Src1Name = getRegName(MI->getOperand(0).getReg());
    DecodeMOVLHPSMask(2, ShuffleMask);
    break;
  case X86::VMOVLHPSrr:
    Src2Name = getRegName(MI->getOperand(2).getReg());
    Src1Name = getRegName(MI->getOperand(1).getReg());
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodeMOVLHPSMask(2, ShuffleMask);
    break;

  case X86::MOVHLPSrr:
    Src2Name = getRegName(MI->getOperand(2).getReg());
    Src1Name = getRegName(MI->getOperand(0).getReg());
    DecodeMOVHLPSMask(2, ShuffleMask);
    break;
  case X86::VMOVHLPSrr:
    Src2Name = getRegName(MI->getOperand(2).getReg());
    Src1Name = getRegName(MI->getOperand(1).getReg());
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodeMOVHLPSMask(2, ShuffleMask);
    break;

  case X86::PSHUFDri:
  case X86::VPSHUFDri:
    Src1Name = getRegName(MI->getOperand(1).getReg());
    // FALL THROUGH.
  case X86::PSHUFDmi:
  case X86::VPSHUFDmi:
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodePSHUFMask(MVT::v4i32, MI->getOperand(MI->getNumOperands()-1).getImm(),
                     ShuffleMask);
    break;
  case X86::VPSHUFDYri:
    Src1Name = getRegName(MI->getOperand(1).getReg());
    // FALL THROUGH.
  case X86::VPSHUFDYmi:
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodePSHUFMask(MVT::v8i32, MI->getOperand(MI->getNumOperands()-1).getImm(),
                    ShuffleMask);
    break;


  case X86::PSHUFHWri:
  case X86::VPSHUFHWri:
    Src1Name = getRegName(MI->getOperand(1).getReg());
    // FALL THROUGH.
  case X86::PSHUFHWmi:
  case X86::VPSHUFHWmi:
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodePSHUFHWMask(MVT::v8i16,
                      MI->getOperand(MI->getNumOperands()-1).getImm(),
                      ShuffleMask);
    break;
  case X86::VPSHUFHWYri:
    Src1Name = getRegName(MI->getOperand(1).getReg());
    // FALL THROUGH.
  case X86::VPSHUFHWYmi:
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodePSHUFHWMask(MVT::v16i16,
                      MI->getOperand(MI->getNumOperands()-1).getImm(),
                      ShuffleMask);
    break;
  case X86::PSHUFLWri:
  case X86::VPSHUFLWri:
    Src1Name = getRegName(MI->getOperand(1).getReg());
    // FALL THROUGH.
  case X86::PSHUFLWmi:
  case X86::VPSHUFLWmi:
    DestName = getRegName(MI->getOperand(0).getReg());
    DecodePSHUFLWMask(MVT::v8i16,
                      MI->getOperand(MI->getNumOperands()-1).getImm(),
                      ShuffleMask);
    break;
  case X86::VPSHUFLWYri:
    Src1Name = getRegName(MI->getOperand(1).getReg());
    // FALL THROUGH.
//.........这里部分代码省略.........

/// Match - Match the pattern string against the input buffer Buffer.  This
/// returns the position that is matched or npos if there is no match.  If
/// there is a match, the size of the matched string is returned in MatchLen.
size_t Pattern::Match(StringRef Buffer, size_t &MatchLen,
                      StringMap<StringRef> &VariableTable) const {
  // If this is the EOF pattern, match it immediately.
  if (CheckTy == Check::CheckEOF) {
    MatchLen = 0;
    return Buffer.size();
  }

  // If this is a fixed string pattern, just match it now.
  if (!FixedStr.empty()) {
    MatchLen = FixedStr.size();
    return Buffer.find(FixedStr);
  }

  // Regex match.

  // If there are variable uses, we need to create a temporary string with the
  // actual value.
  StringRef RegExToMatch = RegExStr;
  std::string TmpStr;
  if (!VariableUses.empty()) {
    TmpStr = RegExStr;

    unsigned InsertOffset = 0;
    for (unsigned i = 0, e = VariableUses.size(); i != e; ++i) {
      std::string Value;

      if (VariableUses[i].first[0] == '@') {
        if (!EvaluateExpression(VariableUses[i].first, Value))
          return StringRef::npos;
      } else {
        StringMap<StringRef>::iterator it =
          VariableTable.find(VariableUses[i].first);
        // If the variable is undefined, return an error.
        if (it == VariableTable.end())
          return StringRef::npos;

        // Look up the value and escape it so that we can put it into the regex.
        Value += Regex::escape(it->second);
      }

      // Plop it into the regex at the adjusted offset.
      TmpStr.insert(TmpStr.begin()+VariableUses[i].second+InsertOffset,
                    Value.begin(), Value.end());
      InsertOffset += Value.size();
    }

    // Match the newly constructed regex.
    RegExToMatch = TmpStr;
  }


  SmallVector<StringRef, 4> MatchInfo;
  if (!Regex(RegExToMatch, Regex::Newline).match(Buffer, &MatchInfo))
    return StringRef::npos;

  // Successful regex match.
  assert(!MatchInfo.empty() && "Didn't get any match");
  StringRef FullMatch = MatchInfo[0];

  // If this defines any variables, remember their values.
  for (std::map<StringRef, unsigned>::const_iterator I = VariableDefs.begin(),
                                                     E = VariableDefs.end();
       I != E; ++I) {
    assert(I->second < MatchInfo.size() && "Internal paren error");
    VariableTable[I->first] = MatchInfo[I->second];
  }

  MatchLen = FullMatch.size();
  return FullMatch.data()-Buffer.data();
}

//.........这里部分代码省略.........
  if (OptLevelO1)
    AddOptimizationPasses(Passes, *FPasses, TM.get(), 1, 0);

  if (OptLevelO2)
    AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 0);

  if (OptLevelOs)
    AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 1);

  if (OptLevelOz)
    AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 2);

  if (OptLevelO3)
    AddOptimizationPasses(Passes, *FPasses, TM.get(), 3, 0);

  if (FPasses) {
    FPasses->doInitialization();
    for (Function &F : *M)
      FPasses->run(F);
    FPasses->doFinalization();
  }

  // Check that the module is well formed on completion of optimization
  if (!NoVerify && !VerifyEach)
    Passes.add(createVerifierPass());

  if (EnableDebugify)
    Passes.add(createCheckDebugifyPass());

  // In run twice mode, we want to make sure the output is bit-by-bit
  // equivalent if we run the pass manager again, so setup two buffers and
  // a stream to write to them. Note that llc does something similar and it
  // may be worth to abstract this out in the future.
  SmallVector<char, 0> Buffer;
  SmallVector<char, 0> CompileTwiceBuffer;
  std::unique_ptr<raw_svector_ostream> BOS;
  raw_ostream *OS = nullptr;

  // Write bitcode or assembly to the output as the last step...
  if (!NoOutput && !AnalyzeOnly) {
    assert(Out);
    OS = &Out->os();
    if (RunTwice) {
      BOS = make_unique<raw_svector_ostream>(Buffer);
      OS = BOS.get();
    }
    if (OutputAssembly) {
      if (EmitSummaryIndex)
        report_fatal_error("Text output is incompatible with -module-summary");
      if (EmitModuleHash)
        report_fatal_error("Text output is incompatible with -module-hash");
      Passes.add(createPrintModulePass(*OS, "", PreserveAssemblyUseListOrder));
    } else if (OutputThinLTOBC)
      Passes.add(createWriteThinLTOBitcodePass(
          *OS, ThinLinkOut ? &ThinLinkOut->os() : nullptr));
    else
      Passes.add(createBitcodeWriterPass(*OS, PreserveBitcodeUseListOrder,
                                         EmitSummaryIndex, EmitModuleHash));
  }

  // Before executing passes, print the final values of the LLVM options.
  cl::PrintOptionValues();

  // If requested, run all passes again with the same pass manager to catch
  // bugs caused by persistent state in the passes
  if (RunTwice) {

/// ProcessLoop - Walk the loop structure in depth first order, ensuring that
/// all loops have preheaders.
///
bool LoopSimplify::ProcessLoop(Loop *L, LPPassManager &LPM) {
  bool Changed = false;
ReprocessLoop:

  // Check to see that no blocks (other than the header) in this loop have
  // predecessors that are not in the loop.  This is not valid for natural
  // loops, but can occur if the blocks are unreachable.  Since they are
  // unreachable we can just shamelessly delete those CFG edges!
  for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
       BB != E; ++BB) {
    if (*BB == L->getHeader()) continue;

    SmallPtrSet<BasicBlock*, 4> BadPreds;
    for (pred_iterator PI = pred_begin(*BB),
         PE = pred_end(*BB); PI != PE; ++PI) {
      BasicBlock *P = *PI;
      if (!L->contains(P))
        BadPreds.insert(P);
    }

    // Delete each unique out-of-loop (and thus dead) predecessor.
    for (SmallPtrSet<BasicBlock*, 4>::iterator I = BadPreds.begin(),
         E = BadPreds.end(); I != E; ++I) {

      DEBUG(dbgs() << "LoopSimplify: Deleting edge from dead predecessor "
                   << (*I)->getName() << "\n");

      // Inform each successor of each dead pred.
      for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI)
        (*SI)->removePredecessor(*I);
      // Zap the dead pred's terminator and replace it with unreachable.
      TerminatorInst *TI = (*I)->getTerminator();
       TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
      (*I)->getTerminator()->eraseFromParent();
      new UnreachableInst((*I)->getContext(), *I);
      Changed = true;
    }
  }

  // If there are exiting blocks with branches on undef, resolve the undef in
  // the direction which will exit the loop. This will help simplify loop
  // trip count computations.
  SmallVector<BasicBlock*, 8> ExitingBlocks;
  L->getExitingBlocks(ExitingBlocks);
  for (SmallVectorImpl<BasicBlock *>::iterator I = ExitingBlocks.begin(),
       E = ExitingBlocks.end(); I != E; ++I)
    if (BranchInst *BI = dyn_cast<BranchInst>((*I)->getTerminator()))
      if (BI->isConditional()) {
        if (UndefValue *Cond = dyn_cast<UndefValue>(BI->getCondition())) {

          DEBUG(dbgs() << "LoopSimplify: Resolving \"br i1 undef\" to exit in "
                       << (*I)->getName() << "\n");

          BI->setCondition(ConstantInt::get(Cond->getType(),
                                            !L->contains(BI->getSuccessor(0))));

          // This may make the loop analyzable, force SCEV recomputation.
          if (SE)
            SE->forgetLoop(L);

          Changed = true;
        }
      }

  // Does the loop already have a preheader?  If so, don't insert one.
  BasicBlock *Preheader = L->getLoopPreheader();
  if (!Preheader) {
    Preheader = InsertPreheaderForLoop(L);
    if (Preheader) {
      ++NumInserted;
      Changed = true;
    }
  }

  // Next, check to make sure that all exit nodes of the loop only have
  // predecessors that are inside of the loop.  This check guarantees that the
  // loop preheader/header will dominate the exit blocks.  If the exit block has
  // predecessors from outside of the loop, split the edge now.
  SmallVector<BasicBlock*, 8> ExitBlocks;
  L->getExitBlocks(ExitBlocks);

  SmallSetVector<BasicBlock *, 8> ExitBlockSet(ExitBlocks.begin(),
                                               ExitBlocks.end());
  for (SmallSetVector<BasicBlock *, 8>::iterator I = ExitBlockSet.begin(),
         E = ExitBlockSet.end(); I != E; ++I) {
    BasicBlock *ExitBlock = *I;
    for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock);
         PI != PE; ++PI)
      // Must be exactly this loop: no subloops, parent loops, or non-loop preds
      // allowed.
      if (!L->contains(*PI)) {
        if (RewriteLoopExitBlock(L, ExitBlock)) {
          ++NumInserted;
          Changed = true;
        }
        break;
      }
//.........这里部分代码省略.........