| //===- CFLGraph.h - Abstract stratified sets implementation. -----*- C++-*-===// | 
 | // | 
 | //                     The LLVM Compiler Infrastructure | 
 | // | 
 | // This file is distributed under the University of Illinois Open Source | 
 | // License. See LICENSE.TXT for details. | 
 | // | 
 | //===----------------------------------------------------------------------===// | 
 | // | 
 | /// \file | 
 | /// This file defines CFLGraph, an auxiliary data structure used by CFL-based | 
 | /// alias analysis. | 
 | // | 
 | //===----------------------------------------------------------------------===// | 
 |  | 
 | #ifndef LLVM_LIB_ANALYSIS_CFLGRAPH_H | 
 | #define LLVM_LIB_ANALYSIS_CFLGRAPH_H | 
 |  | 
 | #include "AliasAnalysisSummary.h" | 
 | #include "llvm/ADT/APInt.h" | 
 | #include "llvm/ADT/DenseMap.h" | 
 | #include "llvm/ADT/SmallVector.h" | 
 | #include "llvm/ADT/iterator_range.h" | 
 | #include "llvm/Analysis/MemoryBuiltins.h" | 
 | #include "llvm/Analysis/TargetLibraryInfo.h" | 
 | #include "llvm/IR/Argument.h" | 
 | #include "llvm/IR/BasicBlock.h" | 
 | #include "llvm/IR/CallSite.h" | 
 | #include "llvm/IR/Constants.h" | 
 | #include "llvm/IR/DataLayout.h" | 
 | #include "llvm/IR/Function.h" | 
 | #include "llvm/IR/GlobalValue.h" | 
 | #include "llvm/IR/InstVisitor.h" | 
 | #include "llvm/IR/InstrTypes.h" | 
 | #include "llvm/IR/Instruction.h" | 
 | #include "llvm/IR/Instructions.h" | 
 | #include "llvm/IR/Operator.h" | 
 | #include "llvm/IR/Type.h" | 
 | #include "llvm/IR/Value.h" | 
 | #include "llvm/Support/Casting.h" | 
 | #include "llvm/Support/ErrorHandling.h" | 
 | #include <cassert> | 
 | #include <cstdint> | 
 | #include <vector> | 
 |  | 
 | namespace llvm { | 
 | namespace cflaa { | 
 |  | 
 | /// The Program Expression Graph (PEG) of CFL analysis | 
 | /// CFLGraph is auxiliary data structure used by CFL-based alias analysis to | 
 | /// describe flow-insensitive pointer-related behaviors. Given an LLVM function, | 
 | /// the main purpose of this graph is to abstract away unrelated facts and | 
 | /// translate the rest into a form that can be easily digested by CFL analyses. | 
 | /// Each Node in the graph is an InstantiatedValue, and each edge represent a | 
 | /// pointer assignment between InstantiatedValue. Pointer | 
 | /// references/dereferences are not explicitly stored in the graph: we | 
 | /// implicitly assume that for each node (X, I) it has a dereference edge to (X, | 
 | /// I+1) and a reference edge to (X, I-1). | 
 | class CFLGraph { | 
 | public: | 
 |   using Node = InstantiatedValue; | 
 |  | 
 |   struct Edge { | 
 |     Node Other; | 
 |     int64_t Offset; | 
 |   }; | 
 |  | 
 |   using EdgeList = std::vector<Edge>; | 
 |  | 
 |   struct NodeInfo { | 
 |     EdgeList Edges, ReverseEdges; | 
 |     AliasAttrs Attr; | 
 |   }; | 
 |  | 
 |   class ValueInfo { | 
 |     std::vector<NodeInfo> Levels; | 
 |  | 
 |   public: | 
 |     bool addNodeToLevel(unsigned Level) { | 
 |       auto NumLevels = Levels.size(); | 
 |       if (NumLevels > Level) | 
 |         return false; | 
 |       Levels.resize(Level + 1); | 
 |       return true; | 
 |     } | 
 |  | 
 |     NodeInfo &getNodeInfoAtLevel(unsigned Level) { | 
 |       assert(Level < Levels.size()); | 
 |       return Levels[Level]; | 
 |     } | 
 |     const NodeInfo &getNodeInfoAtLevel(unsigned Level) const { | 
 |       assert(Level < Levels.size()); | 
 |       return Levels[Level]; | 
 |     } | 
 |  | 
 |     unsigned getNumLevels() const { return Levels.size(); } | 
 |   }; | 
 |  | 
 | private: | 
 |   using ValueMap = DenseMap<Value *, ValueInfo>; | 
 |  | 
 |   ValueMap ValueImpls; | 
 |  | 
 |   NodeInfo *getNode(Node N) { | 
 |     auto Itr = ValueImpls.find(N.Val); | 
 |     if (Itr == ValueImpls.end() || Itr->second.getNumLevels() <= N.DerefLevel) | 
 |       return nullptr; | 
 |     return &Itr->second.getNodeInfoAtLevel(N.DerefLevel); | 
 |   } | 
 |  | 
 | public: | 
 |   using const_value_iterator = ValueMap::const_iterator; | 
 |  | 
 |   bool addNode(Node N, AliasAttrs Attr = AliasAttrs()) { | 
 |     assert(N.Val != nullptr); | 
 |     auto &ValInfo = ValueImpls[N.Val]; | 
 |     auto Changed = ValInfo.addNodeToLevel(N.DerefLevel); | 
 |     ValInfo.getNodeInfoAtLevel(N.DerefLevel).Attr |= Attr; | 
 |     return Changed; | 
 |   } | 
 |  | 
 |   void addAttr(Node N, AliasAttrs Attr) { | 
 |     auto *Info = getNode(N); | 
 |     assert(Info != nullptr); | 
 |     Info->Attr |= Attr; | 
 |   } | 
 |  | 
 |   void addEdge(Node From, Node To, int64_t Offset = 0) { | 
 |     auto *FromInfo = getNode(From); | 
 |     assert(FromInfo != nullptr); | 
 |     auto *ToInfo = getNode(To); | 
 |     assert(ToInfo != nullptr); | 
 |  | 
 |     FromInfo->Edges.push_back(Edge{To, Offset}); | 
 |     ToInfo->ReverseEdges.push_back(Edge{From, Offset}); | 
 |   } | 
 |  | 
 |   const NodeInfo *getNode(Node N) const { | 
 |     auto Itr = ValueImpls.find(N.Val); | 
 |     if (Itr == ValueImpls.end() || Itr->second.getNumLevels() <= N.DerefLevel) | 
 |       return nullptr; | 
 |     return &Itr->second.getNodeInfoAtLevel(N.DerefLevel); | 
 |   } | 
 |  | 
 |   AliasAttrs attrFor(Node N) const { | 
 |     auto *Info = getNode(N); | 
 |     assert(Info != nullptr); | 
 |     return Info->Attr; | 
 |   } | 
 |  | 
 |   iterator_range<const_value_iterator> value_mappings() const { | 
 |     return make_range<const_value_iterator>(ValueImpls.begin(), | 
 |                                             ValueImpls.end()); | 
 |   } | 
 | }; | 
 |  | 
 | ///A builder class used to create CFLGraph instance from a given function | 
 | /// The CFL-AA that uses this builder must provide its own type as a template | 
 | /// argument. This is necessary for interprocedural processing: CFLGraphBuilder | 
 | /// needs a way of obtaining the summary of other functions when callinsts are | 
 | /// encountered. | 
 | /// As a result, we expect the said CFL-AA to expose a getAliasSummary() public | 
 | /// member function that takes a Function& and returns the corresponding summary | 
 | /// as a const AliasSummary*. | 
 | template <typename CFLAA> class CFLGraphBuilder { | 
 |   // Input of the builder | 
 |   CFLAA &Analysis; | 
 |   const TargetLibraryInfo &TLI; | 
 |  | 
 |   // Output of the builder | 
 |   CFLGraph Graph; | 
 |   SmallVector<Value *, 4> ReturnedValues; | 
 |  | 
 |   // Helper class | 
 |   /// Gets the edges our graph should have, based on an Instruction* | 
 |   class GetEdgesVisitor : public InstVisitor<GetEdgesVisitor, void> { | 
 |     CFLAA &AA; | 
 |     const DataLayout &DL; | 
 |     const TargetLibraryInfo &TLI; | 
 |  | 
 |     CFLGraph &Graph; | 
 |     SmallVectorImpl<Value *> &ReturnValues; | 
 |  | 
 |     static bool hasUsefulEdges(ConstantExpr *CE) { | 
 |       // ConstantExpr doesn't have terminators, invokes, or fences, so only | 
 |       // needs | 
 |       // to check for compares. | 
 |       return CE->getOpcode() != Instruction::ICmp && | 
 |              CE->getOpcode() != Instruction::FCmp; | 
 |     } | 
 |  | 
 |     // Returns possible functions called by CS into the given SmallVectorImpl. | 
 |     // Returns true if targets found, false otherwise. | 
 |     static bool getPossibleTargets(CallSite CS, | 
 |                                    SmallVectorImpl<Function *> &Output) { | 
 |       if (auto *Fn = CS.getCalledFunction()) { | 
 |         Output.push_back(Fn); | 
 |         return true; | 
 |       } | 
 |  | 
 |       // TODO: If the call is indirect, we might be able to enumerate all | 
 |       // potential | 
 |       // targets of the call and return them, rather than just failing. | 
 |       return false; | 
 |     } | 
 |  | 
 |     void addNode(Value *Val, AliasAttrs Attr = AliasAttrs()) { | 
 |       assert(Val != nullptr && Val->getType()->isPointerTy()); | 
 |       if (auto GVal = dyn_cast<GlobalValue>(Val)) { | 
 |         if (Graph.addNode(InstantiatedValue{GVal, 0}, | 
 |                           getGlobalOrArgAttrFromValue(*GVal))) | 
 |           Graph.addNode(InstantiatedValue{GVal, 1}, getAttrUnknown()); | 
 |       } else if (auto CExpr = dyn_cast<ConstantExpr>(Val)) { | 
 |         if (hasUsefulEdges(CExpr)) { | 
 |           if (Graph.addNode(InstantiatedValue{CExpr, 0})) | 
 |             visitConstantExpr(CExpr); | 
 |         } | 
 |       } else | 
 |         Graph.addNode(InstantiatedValue{Val, 0}, Attr); | 
 |     } | 
 |  | 
 |     void addAssignEdge(Value *From, Value *To, int64_t Offset = 0) { | 
 |       assert(From != nullptr && To != nullptr); | 
 |       if (!From->getType()->isPointerTy() || !To->getType()->isPointerTy()) | 
 |         return; | 
 |       addNode(From); | 
 |       if (To != From) { | 
 |         addNode(To); | 
 |         Graph.addEdge(InstantiatedValue{From, 0}, InstantiatedValue{To, 0}, | 
 |                       Offset); | 
 |       } | 
 |     } | 
 |  | 
 |     void addDerefEdge(Value *From, Value *To, bool IsRead) { | 
 |       assert(From != nullptr && To != nullptr); | 
 |       // FIXME: This is subtly broken, due to how we model some instructions | 
 |       // (e.g. extractvalue, extractelement) as loads. Since those take | 
 |       // non-pointer operands, we'll entirely skip adding edges for those. | 
 |       // | 
 |       // addAssignEdge seems to have a similar issue with insertvalue, etc. | 
 |       if (!From->getType()->isPointerTy() || !To->getType()->isPointerTy()) | 
 |         return; | 
 |       addNode(From); | 
 |       addNode(To); | 
 |       if (IsRead) { | 
 |         Graph.addNode(InstantiatedValue{From, 1}); | 
 |         Graph.addEdge(InstantiatedValue{From, 1}, InstantiatedValue{To, 0}); | 
 |       } else { | 
 |         Graph.addNode(InstantiatedValue{To, 1}); | 
 |         Graph.addEdge(InstantiatedValue{From, 0}, InstantiatedValue{To, 1}); | 
 |       } | 
 |     } | 
 |  | 
 |     void addLoadEdge(Value *From, Value *To) { addDerefEdge(From, To, true); } | 
 |     void addStoreEdge(Value *From, Value *To) { addDerefEdge(From, To, false); } | 
 |  | 
 |   public: | 
 |     GetEdgesVisitor(CFLGraphBuilder &Builder, const DataLayout &DL) | 
 |         : AA(Builder.Analysis), DL(DL), TLI(Builder.TLI), Graph(Builder.Graph), | 
 |           ReturnValues(Builder.ReturnedValues) {} | 
 |  | 
 |     void visitInstruction(Instruction &) { | 
 |       llvm_unreachable("Unsupported instruction encountered"); | 
 |     } | 
 |  | 
 |     void visitReturnInst(ReturnInst &Inst) { | 
 |       if (auto RetVal = Inst.getReturnValue()) { | 
 |         if (RetVal->getType()->isPointerTy()) { | 
 |           addNode(RetVal); | 
 |           ReturnValues.push_back(RetVal); | 
 |         } | 
 |       } | 
 |     } | 
 |  | 
 |     void visitPtrToIntInst(PtrToIntInst &Inst) { | 
 |       auto *Ptr = Inst.getOperand(0); | 
 |       addNode(Ptr, getAttrEscaped()); | 
 |     } | 
 |  | 
 |     void visitIntToPtrInst(IntToPtrInst &Inst) { | 
 |       auto *Ptr = &Inst; | 
 |       addNode(Ptr, getAttrUnknown()); | 
 |     } | 
 |  | 
 |     void visitCastInst(CastInst &Inst) { | 
 |       auto *Src = Inst.getOperand(0); | 
 |       addAssignEdge(Src, &Inst); | 
 |     } | 
 |  | 
 |     void visitBinaryOperator(BinaryOperator &Inst) { | 
 |       auto *Op1 = Inst.getOperand(0); | 
 |       auto *Op2 = Inst.getOperand(1); | 
 |       addAssignEdge(Op1, &Inst); | 
 |       addAssignEdge(Op2, &Inst); | 
 |     } | 
 |  | 
 |     void visitAtomicCmpXchgInst(AtomicCmpXchgInst &Inst) { | 
 |       auto *Ptr = Inst.getPointerOperand(); | 
 |       auto *Val = Inst.getNewValOperand(); | 
 |       addStoreEdge(Val, Ptr); | 
 |     } | 
 |  | 
 |     void visitAtomicRMWInst(AtomicRMWInst &Inst) { | 
 |       auto *Ptr = Inst.getPointerOperand(); | 
 |       auto *Val = Inst.getValOperand(); | 
 |       addStoreEdge(Val, Ptr); | 
 |     } | 
 |  | 
 |     void visitPHINode(PHINode &Inst) { | 
 |       for (Value *Val : Inst.incoming_values()) | 
 |         addAssignEdge(Val, &Inst); | 
 |     } | 
 |  | 
 |     void visitGEP(GEPOperator &GEPOp) { | 
 |       uint64_t Offset = UnknownOffset; | 
 |       APInt APOffset(DL.getPointerSizeInBits(GEPOp.getPointerAddressSpace()), | 
 |                      0); | 
 |       if (GEPOp.accumulateConstantOffset(DL, APOffset)) | 
 |         Offset = APOffset.getSExtValue(); | 
 |  | 
 |       auto *Op = GEPOp.getPointerOperand(); | 
 |       addAssignEdge(Op, &GEPOp, Offset); | 
 |     } | 
 |  | 
 |     void visitGetElementPtrInst(GetElementPtrInst &Inst) { | 
 |       auto *GEPOp = cast<GEPOperator>(&Inst); | 
 |       visitGEP(*GEPOp); | 
 |     } | 
 |  | 
 |     void visitSelectInst(SelectInst &Inst) { | 
 |       // Condition is not processed here (The actual statement producing | 
 |       // the condition result is processed elsewhere). For select, the | 
 |       // condition is evaluated, but not loaded, stored, or assigned | 
 |       // simply as a result of being the condition of a select. | 
 |  | 
 |       auto *TrueVal = Inst.getTrueValue(); | 
 |       auto *FalseVal = Inst.getFalseValue(); | 
 |       addAssignEdge(TrueVal, &Inst); | 
 |       addAssignEdge(FalseVal, &Inst); | 
 |     } | 
 |  | 
 |     void visitAllocaInst(AllocaInst &Inst) { addNode(&Inst); } | 
 |  | 
 |     void visitLoadInst(LoadInst &Inst) { | 
 |       auto *Ptr = Inst.getPointerOperand(); | 
 |       auto *Val = &Inst; | 
 |       addLoadEdge(Ptr, Val); | 
 |     } | 
 |  | 
 |     void visitStoreInst(StoreInst &Inst) { | 
 |       auto *Ptr = Inst.getPointerOperand(); | 
 |       auto *Val = Inst.getValueOperand(); | 
 |       addStoreEdge(Val, Ptr); | 
 |     } | 
 |  | 
 |     void visitVAArgInst(VAArgInst &Inst) { | 
 |       // We can't fully model va_arg here. For *Ptr = Inst.getOperand(0), it | 
 |       // does | 
 |       // two things: | 
 |       //  1. Loads a value from *((T*)*Ptr). | 
 |       //  2. Increments (stores to) *Ptr by some target-specific amount. | 
 |       // For now, we'll handle this like a landingpad instruction (by placing | 
 |       // the | 
 |       // result in its own group, and having that group alias externals). | 
 |       if (Inst.getType()->isPointerTy()) | 
 |         addNode(&Inst, getAttrUnknown()); | 
 |     } | 
 |  | 
 |     static bool isFunctionExternal(Function *Fn) { | 
 |       return !Fn->hasExactDefinition(); | 
 |     } | 
 |  | 
 |     bool tryInterproceduralAnalysis(CallSite CS, | 
 |                                     const SmallVectorImpl<Function *> &Fns) { | 
 |       assert(Fns.size() > 0); | 
 |  | 
 |       if (CS.arg_size() > MaxSupportedArgsInSummary) | 
 |         return false; | 
 |  | 
 |       // Exit early if we'll fail anyway | 
 |       for (auto *Fn : Fns) { | 
 |         if (isFunctionExternal(Fn) || Fn->isVarArg()) | 
 |           return false; | 
 |         // Fail if the caller does not provide enough arguments | 
 |         assert(Fn->arg_size() <= CS.arg_size()); | 
 |         if (!AA.getAliasSummary(*Fn)) | 
 |           return false; | 
 |       } | 
 |  | 
 |       for (auto *Fn : Fns) { | 
 |         auto Summary = AA.getAliasSummary(*Fn); | 
 |         assert(Summary != nullptr); | 
 |  | 
 |         auto &RetParamRelations = Summary->RetParamRelations; | 
 |         for (auto &Relation : RetParamRelations) { | 
 |           auto IRelation = instantiateExternalRelation(Relation, CS); | 
 |           if (IRelation.hasValue()) { | 
 |             Graph.addNode(IRelation->From); | 
 |             Graph.addNode(IRelation->To); | 
 |             Graph.addEdge(IRelation->From, IRelation->To); | 
 |           } | 
 |         } | 
 |  | 
 |         auto &RetParamAttributes = Summary->RetParamAttributes; | 
 |         for (auto &Attribute : RetParamAttributes) { | 
 |           auto IAttr = instantiateExternalAttribute(Attribute, CS); | 
 |           if (IAttr.hasValue()) | 
 |             Graph.addNode(IAttr->IValue, IAttr->Attr); | 
 |         } | 
 |       } | 
 |  | 
 |       return true; | 
 |     } | 
 |  | 
 |     void visitCallSite(CallSite CS) { | 
 |       auto Inst = CS.getInstruction(); | 
 |  | 
 |       // Make sure all arguments and return value are added to the graph first | 
 |       for (Value *V : CS.args()) | 
 |         if (V->getType()->isPointerTy()) | 
 |           addNode(V); | 
 |       if (Inst->getType()->isPointerTy()) | 
 |         addNode(Inst); | 
 |  | 
 |       // Check if Inst is a call to a library function that | 
 |       // allocates/deallocates on the heap. Those kinds of functions do not | 
 |       // introduce any aliases. | 
 |       // TODO: address other common library functions such as realloc(), | 
 |       // strdup(), etc. | 
 |       if (isMallocOrCallocLikeFn(Inst, &TLI) || isFreeCall(Inst, &TLI)) | 
 |         return; | 
 |  | 
 |       // TODO: Add support for noalias args/all the other fun function | 
 |       // attributes that we can tack on. | 
 |       SmallVector<Function *, 4> Targets; | 
 |       if (getPossibleTargets(CS, Targets)) | 
 |         if (tryInterproceduralAnalysis(CS, Targets)) | 
 |           return; | 
 |  | 
 |       // Because the function is opaque, we need to note that anything | 
 |       // could have happened to the arguments (unless the function is marked | 
 |       // readonly or readnone), and that the result could alias just about | 
 |       // anything, too (unless the result is marked noalias). | 
 |       if (!CS.onlyReadsMemory()) | 
 |         for (Value *V : CS.args()) { | 
 |           if (V->getType()->isPointerTy()) { | 
 |             // The argument itself escapes. | 
 |             Graph.addAttr(InstantiatedValue{V, 0}, getAttrEscaped()); | 
 |             // The fate of argument memory is unknown. Note that since | 
 |             // AliasAttrs is transitive with respect to dereference, we only | 
 |             // need to specify it for the first-level memory. | 
 |             Graph.addNode(InstantiatedValue{V, 1}, getAttrUnknown()); | 
 |           } | 
 |         } | 
 |  | 
 |       if (Inst->getType()->isPointerTy()) { | 
 |         auto *Fn = CS.getCalledFunction(); | 
 |         if (Fn == nullptr || !Fn->returnDoesNotAlias()) | 
 |           // No need to call addNode() since we've added Inst at the | 
 |           // beginning of this function and we know it is not a global. | 
 |           Graph.addAttr(InstantiatedValue{Inst, 0}, getAttrUnknown()); | 
 |       } | 
 |     } | 
 |  | 
 |     /// Because vectors/aggregates are immutable and unaddressable, there's | 
 |     /// nothing we can do to coax a value out of them, other than calling | 
 |     /// Extract{Element,Value}. We can effectively treat them as pointers to | 
 |     /// arbitrary memory locations we can store in and load from. | 
 |     void visitExtractElementInst(ExtractElementInst &Inst) { | 
 |       auto *Ptr = Inst.getVectorOperand(); | 
 |       auto *Val = &Inst; | 
 |       addLoadEdge(Ptr, Val); | 
 |     } | 
 |  | 
 |     void visitInsertElementInst(InsertElementInst &Inst) { | 
 |       auto *Vec = Inst.getOperand(0); | 
 |       auto *Val = Inst.getOperand(1); | 
 |       addAssignEdge(Vec, &Inst); | 
 |       addStoreEdge(Val, &Inst); | 
 |     } | 
 |  | 
 |     void visitLandingPadInst(LandingPadInst &Inst) { | 
 |       // Exceptions come from "nowhere", from our analysis' perspective. | 
 |       // So we place the instruction its own group, noting that said group may | 
 |       // alias externals | 
 |       if (Inst.getType()->isPointerTy()) | 
 |         addNode(&Inst, getAttrUnknown()); | 
 |     } | 
 |  | 
 |     void visitInsertValueInst(InsertValueInst &Inst) { | 
 |       auto *Agg = Inst.getOperand(0); | 
 |       auto *Val = Inst.getOperand(1); | 
 |       addAssignEdge(Agg, &Inst); | 
 |       addStoreEdge(Val, &Inst); | 
 |     } | 
 |  | 
 |     void visitExtractValueInst(ExtractValueInst &Inst) { | 
 |       auto *Ptr = Inst.getAggregateOperand(); | 
 |       addLoadEdge(Ptr, &Inst); | 
 |     } | 
 |  | 
 |     void visitShuffleVectorInst(ShuffleVectorInst &Inst) { | 
 |       auto *From1 = Inst.getOperand(0); | 
 |       auto *From2 = Inst.getOperand(1); | 
 |       addAssignEdge(From1, &Inst); | 
 |       addAssignEdge(From2, &Inst); | 
 |     } | 
 |  | 
 |     void visitConstantExpr(ConstantExpr *CE) { | 
 |       switch (CE->getOpcode()) { | 
 |       case Instruction::GetElementPtr: { | 
 |         auto GEPOp = cast<GEPOperator>(CE); | 
 |         visitGEP(*GEPOp); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::PtrToInt: { | 
 |         addNode(CE->getOperand(0), getAttrEscaped()); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::IntToPtr: { | 
 |         addNode(CE, getAttrUnknown()); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::BitCast: | 
 |       case Instruction::AddrSpaceCast: | 
 |       case Instruction::Trunc: | 
 |       case Instruction::ZExt: | 
 |       case Instruction::SExt: | 
 |       case Instruction::FPExt: | 
 |       case Instruction::FPTrunc: | 
 |       case Instruction::UIToFP: | 
 |       case Instruction::SIToFP: | 
 |       case Instruction::FPToUI: | 
 |       case Instruction::FPToSI: { | 
 |         addAssignEdge(CE->getOperand(0), CE); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::Select: { | 
 |         addAssignEdge(CE->getOperand(1), CE); | 
 |         addAssignEdge(CE->getOperand(2), CE); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::InsertElement: | 
 |       case Instruction::InsertValue: { | 
 |         addAssignEdge(CE->getOperand(0), CE); | 
 |         addStoreEdge(CE->getOperand(1), CE); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::ExtractElement: | 
 |       case Instruction::ExtractValue: { | 
 |         addLoadEdge(CE->getOperand(0), CE); | 
 |         break; | 
 |       } | 
 |  | 
 |       case Instruction::Add: | 
 |       case Instruction::Sub: | 
 |       case Instruction::FSub: | 
 |       case Instruction::Mul: | 
 |       case Instruction::FMul: | 
 |       case Instruction::UDiv: | 
 |       case Instruction::SDiv: | 
 |       case Instruction::FDiv: | 
 |       case Instruction::URem: | 
 |       case Instruction::SRem: | 
 |       case Instruction::FRem: | 
 |       case Instruction::And: | 
 |       case Instruction::Or: | 
 |       case Instruction::Xor: | 
 |       case Instruction::Shl: | 
 |       case Instruction::LShr: | 
 |       case Instruction::AShr: | 
 |       case Instruction::ICmp: | 
 |       case Instruction::FCmp: | 
 |       case Instruction::ShuffleVector: { | 
 |         addAssignEdge(CE->getOperand(0), CE); | 
 |         addAssignEdge(CE->getOperand(1), CE); | 
 |         break; | 
 |       } | 
 |  | 
 |       default: | 
 |         llvm_unreachable("Unknown instruction type encountered!"); | 
 |       } | 
 |     } | 
 |   }; | 
 |  | 
 |   // Helper functions | 
 |  | 
 |   // Determines whether or not we an instruction is useless to us (e.g. | 
 |   // FenceInst) | 
 |   static bool hasUsefulEdges(Instruction *Inst) { | 
 |     bool IsNonInvokeRetTerminator = isa<TerminatorInst>(Inst) && | 
 |                                     !isa<InvokeInst>(Inst) && | 
 |                                     !isa<ReturnInst>(Inst); | 
 |     return !isa<CmpInst>(Inst) && !isa<FenceInst>(Inst) && | 
 |            !IsNonInvokeRetTerminator; | 
 |   } | 
 |  | 
 |   void addArgumentToGraph(Argument &Arg) { | 
 |     if (Arg.getType()->isPointerTy()) { | 
 |       Graph.addNode(InstantiatedValue{&Arg, 0}, | 
 |                     getGlobalOrArgAttrFromValue(Arg)); | 
 |       // Pointees of a formal parameter is known to the caller | 
 |       Graph.addNode(InstantiatedValue{&Arg, 1}, getAttrCaller()); | 
 |     } | 
 |   } | 
 |  | 
 |   // Given an Instruction, this will add it to the graph, along with any | 
 |   // Instructions that are potentially only available from said Instruction | 
 |   // For example, given the following line: | 
 |   //   %0 = load i16* getelementptr ([1 x i16]* @a, 0, 0), align 2 | 
 |   // addInstructionToGraph would add both the `load` and `getelementptr` | 
 |   // instructions to the graph appropriately. | 
 |   void addInstructionToGraph(GetEdgesVisitor &Visitor, Instruction &Inst) { | 
 |     if (!hasUsefulEdges(&Inst)) | 
 |       return; | 
 |  | 
 |     Visitor.visit(Inst); | 
 |   } | 
 |  | 
 |   // Builds the graph needed for constructing the StratifiedSets for the given | 
 |   // function | 
 |   void buildGraphFrom(Function &Fn) { | 
 |     GetEdgesVisitor Visitor(*this, Fn.getParent()->getDataLayout()); | 
 |  | 
 |     for (auto &Bb : Fn.getBasicBlockList()) | 
 |       for (auto &Inst : Bb.getInstList()) | 
 |         addInstructionToGraph(Visitor, Inst); | 
 |  | 
 |     for (auto &Arg : Fn.args()) | 
 |       addArgumentToGraph(Arg); | 
 |   } | 
 |  | 
 | public: | 
 |   CFLGraphBuilder(CFLAA &Analysis, const TargetLibraryInfo &TLI, Function &Fn) | 
 |       : Analysis(Analysis), TLI(TLI) { | 
 |     buildGraphFrom(Fn); | 
 |   } | 
 |  | 
 |   const CFLGraph &getCFLGraph() const { return Graph; } | 
 |   const SmallVector<Value *, 4> &getReturnValues() const { | 
 |     return ReturnedValues; | 
 |   } | 
 | }; | 
 |  | 
 | } // end namespace cflaa | 
 | } // end namespace llvm | 
 |  | 
 | #endif // LLVM_LIB_ANALYSIS_CFLGRAPH_H |