| //===- FunctionAttrs.cpp - Pass which marks functions attributes ----------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements a simple interprocedural pass which walks the |
| // call-graph, looking for functions which do not access or only read |
| // non-local memory, and marking them readnone/readonly. It does the |
| // same with function arguments independently, marking them readonly/ |
| // readnone/nocapture. Finally, well-known library call declarations |
| // are marked with all attributes that are consistent with the |
| // function's standard definition. This pass is implemented as a |
| // bottom-up traversal of the call-graph. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/IPO.h" |
| #include "llvm/ADT/SCCIterator.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/Analysis/AliasAnalysis.h" |
| #include "llvm/Analysis/CallGraph.h" |
| #include "llvm/Analysis/CallGraphSCCPass.h" |
| #include "llvm/Analysis/CaptureTracking.h" |
| #include "llvm/IR/GlobalVariable.h" |
| #include "llvm/IR/InstIterator.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/LLVMContext.h" |
| #include "llvm/Target/TargetLibraryInfo.h" |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "functionattrs" |
| |
| STATISTIC(NumReadNone, "Number of functions marked readnone"); |
| STATISTIC(NumReadOnly, "Number of functions marked readonly"); |
| STATISTIC(NumNoCapture, "Number of arguments marked nocapture"); |
| STATISTIC(NumReadNoneArg, "Number of arguments marked readnone"); |
| STATISTIC(NumReadOnlyArg, "Number of arguments marked readonly"); |
| STATISTIC(NumNoAlias, "Number of function returns marked noalias"); |
| STATISTIC(NumAnnotated, "Number of attributes added to library functions"); |
| |
| namespace { |
| struct FunctionAttrs : public CallGraphSCCPass { |
| static char ID; // Pass identification, replacement for typeid |
| FunctionAttrs() : CallGraphSCCPass(ID), AA(nullptr) { |
| initializeFunctionAttrsPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| // runOnSCC - Analyze the SCC, performing the transformation if possible. |
| bool runOnSCC(CallGraphSCC &SCC) override; |
| |
| // AddReadAttrs - Deduce readonly/readnone attributes for the SCC. |
| bool AddReadAttrs(const CallGraphSCC &SCC); |
| |
| // AddArgumentAttrs - Deduce nocapture attributes for the SCC. |
| bool AddArgumentAttrs(const CallGraphSCC &SCC); |
| |
| // IsFunctionMallocLike - Does this function allocate new memory? |
| bool IsFunctionMallocLike(Function *F, |
| SmallPtrSet<Function*, 8> &) const; |
| |
| // AddNoAliasAttrs - Deduce noalias attributes for the SCC. |
| bool AddNoAliasAttrs(const CallGraphSCC &SCC); |
| |
| // Utility methods used by inferPrototypeAttributes to add attributes |
| // and maintain annotation statistics. |
| |
| void setDoesNotAccessMemory(Function &F) { |
| if (!F.doesNotAccessMemory()) { |
| F.setDoesNotAccessMemory(); |
| ++NumAnnotated; |
| } |
| } |
| |
| void setOnlyReadsMemory(Function &F) { |
| if (!F.onlyReadsMemory()) { |
| F.setOnlyReadsMemory(); |
| ++NumAnnotated; |
| } |
| } |
| |
| void setDoesNotThrow(Function &F) { |
| if (!F.doesNotThrow()) { |
| F.setDoesNotThrow(); |
| ++NumAnnotated; |
| } |
| } |
| |
| void setDoesNotCapture(Function &F, unsigned n) { |
| if (!F.doesNotCapture(n)) { |
| F.setDoesNotCapture(n); |
| ++NumAnnotated; |
| } |
| } |
| |
| void setOnlyReadsMemory(Function &F, unsigned n) { |
| if (!F.onlyReadsMemory(n)) { |
| F.setOnlyReadsMemory(n); |
| ++NumAnnotated; |
| } |
| } |
| |
| void setDoesNotAlias(Function &F, unsigned n) { |
| if (!F.doesNotAlias(n)) { |
| F.setDoesNotAlias(n); |
| ++NumAnnotated; |
| } |
| } |
| |
| // inferPrototypeAttributes - Analyze the name and prototype of the |
| // given function and set any applicable attributes. Returns true |
| // if any attributes were set and false otherwise. |
| bool inferPrototypeAttributes(Function &F); |
| |
| // annotateLibraryCalls - Adds attributes to well-known standard library |
| // call declarations. |
| bool annotateLibraryCalls(const CallGraphSCC &SCC); |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.setPreservesCFG(); |
| AU.addRequired<AliasAnalysis>(); |
| AU.addRequired<TargetLibraryInfo>(); |
| CallGraphSCCPass::getAnalysisUsage(AU); |
| } |
| |
| private: |
| AliasAnalysis *AA; |
| TargetLibraryInfo *TLI; |
| }; |
| } |
| |
| char FunctionAttrs::ID = 0; |
| INITIALIZE_PASS_BEGIN(FunctionAttrs, "functionattrs", |
| "Deduce function attributes", false, false) |
| INITIALIZE_AG_DEPENDENCY(AliasAnalysis) |
| INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass) |
| INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) |
| INITIALIZE_PASS_END(FunctionAttrs, "functionattrs", |
| "Deduce function attributes", false, false) |
| |
| Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); } |
| |
| |
| /// AddReadAttrs - Deduce readonly/readnone attributes for the SCC. |
| bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) { |
| SmallPtrSet<Function*, 8> SCCNodes; |
| |
| // Fill SCCNodes with the elements of the SCC. Used for quickly |
| // looking up whether a given CallGraphNode is in this SCC. |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) |
| SCCNodes.insert((*I)->getFunction()); |
| |
| // Check if any of the functions in the SCC read or write memory. If they |
| // write memory then they can't be marked readnone or readonly. |
| bool ReadsMemory = false; |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| |
| if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) |
| // External node or node we don't want to optimize - assume it may write |
| // memory and give up. |
| return false; |
| |
| AliasAnalysis::ModRefBehavior MRB = AA->getModRefBehavior(F); |
| if (MRB == AliasAnalysis::DoesNotAccessMemory) |
| // Already perfect! |
| continue; |
| |
| // Definitions with weak linkage may be overridden at linktime with |
| // something that writes memory, so treat them like declarations. |
| if (F->isDeclaration() || F->mayBeOverridden()) { |
| if (!AliasAnalysis::onlyReadsMemory(MRB)) |
| // May write memory. Just give up. |
| return false; |
| |
| ReadsMemory = true; |
| continue; |
| } |
| |
| // Scan the function body for instructions that may read or write memory. |
| for (inst_iterator II = inst_begin(F), E = inst_end(F); II != E; ++II) { |
| Instruction *I = &*II; |
| |
| // Some instructions can be ignored even if they read or write memory. |
| // Detect these now, skipping to the next instruction if one is found. |
| CallSite CS(cast<Value>(I)); |
| if (CS) { |
| // Ignore calls to functions in the same SCC. |
| if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction())) |
| continue; |
| AliasAnalysis::ModRefBehavior MRB = AA->getModRefBehavior(CS); |
| // If the call doesn't access arbitrary memory, we may be able to |
| // figure out something. |
| if (AliasAnalysis::onlyAccessesArgPointees(MRB)) { |
| // If the call does access argument pointees, check each argument. |
| if (AliasAnalysis::doesAccessArgPointees(MRB)) |
| // Check whether all pointer arguments point to local memory, and |
| // ignore calls that only access local memory. |
| for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end(); |
| CI != CE; ++CI) { |
| Value *Arg = *CI; |
| if (Arg->getType()->isPointerTy()) { |
| AAMDNodes AAInfo; |
| I->getAAMetadata(AAInfo); |
| |
| AliasAnalysis::Location Loc(Arg, |
| AliasAnalysis::UnknownSize, AAInfo); |
| if (!AA->pointsToConstantMemory(Loc, /*OrLocal=*/true)) { |
| if (MRB & AliasAnalysis::Mod) |
| // Writes non-local memory. Give up. |
| return false; |
| if (MRB & AliasAnalysis::Ref) |
| // Ok, it reads non-local memory. |
| ReadsMemory = true; |
| } |
| } |
| } |
| continue; |
| } |
| // The call could access any memory. If that includes writes, give up. |
| if (MRB & AliasAnalysis::Mod) |
| return false; |
| // If it reads, note it. |
| if (MRB & AliasAnalysis::Ref) |
| ReadsMemory = true; |
| continue; |
| } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| // Ignore non-volatile loads from local memory. (Atomic is okay here.) |
| if (!LI->isVolatile()) { |
| AliasAnalysis::Location Loc = AA->getLocation(LI); |
| if (AA->pointsToConstantMemory(Loc, /*OrLocal=*/true)) |
| continue; |
| } |
| } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) { |
| // Ignore non-volatile stores to local memory. (Atomic is okay here.) |
| if (!SI->isVolatile()) { |
| AliasAnalysis::Location Loc = AA->getLocation(SI); |
| if (AA->pointsToConstantMemory(Loc, /*OrLocal=*/true)) |
| continue; |
| } |
| } else if (VAArgInst *VI = dyn_cast<VAArgInst>(I)) { |
| // Ignore vaargs on local memory. |
| AliasAnalysis::Location Loc = AA->getLocation(VI); |
| if (AA->pointsToConstantMemory(Loc, /*OrLocal=*/true)) |
| continue; |
| } |
| |
| // Any remaining instructions need to be taken seriously! Check if they |
| // read or write memory. |
| if (I->mayWriteToMemory()) |
| // Writes memory. Just give up. |
| return false; |
| |
| // If this instruction may read memory, remember that. |
| ReadsMemory |= I->mayReadFromMemory(); |
| } |
| } |
| |
| // Success! Functions in this SCC do not access memory, or only read memory. |
| // Give them the appropriate attribute. |
| bool MadeChange = false; |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| |
| if (F->doesNotAccessMemory()) |
| // Already perfect! |
| continue; |
| |
| if (F->onlyReadsMemory() && ReadsMemory) |
| // No change. |
| continue; |
| |
| MadeChange = true; |
| |
| // Clear out any existing attributes. |
| AttrBuilder B; |
| B.addAttribute(Attribute::ReadOnly) |
| .addAttribute(Attribute::ReadNone); |
| F->removeAttributes(AttributeSet::FunctionIndex, |
| AttributeSet::get(F->getContext(), |
| AttributeSet::FunctionIndex, B)); |
| |
| // Add in the new attribute. |
| F->addAttribute(AttributeSet::FunctionIndex, |
| ReadsMemory ? Attribute::ReadOnly : Attribute::ReadNone); |
| |
| if (ReadsMemory) |
| ++NumReadOnly; |
| else |
| ++NumReadNone; |
| } |
| |
| return MadeChange; |
| } |
| |
| namespace { |
| // For a given pointer Argument, this retains a list of Arguments of functions |
| // in the same SCC that the pointer data flows into. We use this to build an |
| // SCC of the arguments. |
| struct ArgumentGraphNode { |
| Argument *Definition; |
| SmallVector<ArgumentGraphNode*, 4> Uses; |
| }; |
| |
| class ArgumentGraph { |
| // We store pointers to ArgumentGraphNode objects, so it's important that |
| // that they not move around upon insert. |
| typedef std::map<Argument*, ArgumentGraphNode> ArgumentMapTy; |
| |
| ArgumentMapTy ArgumentMap; |
| |
| // There is no root node for the argument graph, in fact: |
| // void f(int *x, int *y) { if (...) f(x, y); } |
| // is an example where the graph is disconnected. The SCCIterator requires a |
| // single entry point, so we maintain a fake ("synthetic") root node that |
| // uses every node. Because the graph is directed and nothing points into |
| // the root, it will not participate in any SCCs (except for its own). |
| ArgumentGraphNode SyntheticRoot; |
| |
| public: |
| ArgumentGraph() { SyntheticRoot.Definition = nullptr; } |
| |
| typedef SmallVectorImpl<ArgumentGraphNode*>::iterator iterator; |
| |
| iterator begin() { return SyntheticRoot.Uses.begin(); } |
| iterator end() { return SyntheticRoot.Uses.end(); } |
| ArgumentGraphNode *getEntryNode() { return &SyntheticRoot; } |
| |
| ArgumentGraphNode *operator[](Argument *A) { |
| ArgumentGraphNode &Node = ArgumentMap[A]; |
| Node.Definition = A; |
| SyntheticRoot.Uses.push_back(&Node); |
| return &Node; |
| } |
| }; |
| |
| // This tracker checks whether callees are in the SCC, and if so it does not |
| // consider that a capture, instead adding it to the "Uses" list and |
| // continuing with the analysis. |
| struct ArgumentUsesTracker : public CaptureTracker { |
| ArgumentUsesTracker(const SmallPtrSet<Function*, 8> &SCCNodes) |
| : Captured(false), SCCNodes(SCCNodes) {} |
| |
| void tooManyUses() override { Captured = true; } |
| |
| bool captured(const Use *U) override { |
| CallSite CS(U->getUser()); |
| if (!CS.getInstruction()) { Captured = true; return true; } |
| |
| Function *F = CS.getCalledFunction(); |
| if (!F || !SCCNodes.count(F)) { Captured = true; return true; } |
| |
| bool Found = false; |
| Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end(); |
| for (CallSite::arg_iterator PI = CS.arg_begin(), PE = CS.arg_end(); |
| PI != PE; ++PI, ++AI) { |
| if (AI == AE) { |
| assert(F->isVarArg() && "More params than args in non-varargs call"); |
| Captured = true; |
| return true; |
| } |
| if (PI == U) { |
| Uses.push_back(AI); |
| Found = true; |
| break; |
| } |
| } |
| assert(Found && "Capturing call-site captured nothing?"); |
| (void)Found; |
| return false; |
| } |
| |
| bool Captured; // True only if certainly captured (used outside our SCC). |
| SmallVector<Argument*, 4> Uses; // Uses within our SCC. |
| |
| const SmallPtrSet<Function*, 8> &SCCNodes; |
| }; |
| } |
| |
| namespace llvm { |
| template<> struct GraphTraits<ArgumentGraphNode*> { |
| typedef ArgumentGraphNode NodeType; |
| typedef SmallVectorImpl<ArgumentGraphNode*>::iterator ChildIteratorType; |
| |
| static inline NodeType *getEntryNode(NodeType *A) { return A; } |
| static inline ChildIteratorType child_begin(NodeType *N) { |
| return N->Uses.begin(); |
| } |
| static inline ChildIteratorType child_end(NodeType *N) { |
| return N->Uses.end(); |
| } |
| }; |
| template<> struct GraphTraits<ArgumentGraph*> |
| : public GraphTraits<ArgumentGraphNode*> { |
| static NodeType *getEntryNode(ArgumentGraph *AG) { |
| return AG->getEntryNode(); |
| } |
| static ChildIteratorType nodes_begin(ArgumentGraph *AG) { |
| return AG->begin(); |
| } |
| static ChildIteratorType nodes_end(ArgumentGraph *AG) { |
| return AG->end(); |
| } |
| }; |
| } |
| |
| // Returns Attribute::None, Attribute::ReadOnly or Attribute::ReadNone. |
| static Attribute::AttrKind |
| determinePointerReadAttrs(Argument *A, |
| const SmallPtrSet<Argument*, 8> &SCCNodes) { |
| |
| SmallVector<Use*, 32> Worklist; |
| SmallSet<Use*, 32> Visited; |
| int Count = 0; |
| |
| // inalloca arguments are always clobbered by the call. |
| if (A->hasInAllocaAttr()) |
| return Attribute::None; |
| |
| bool IsRead = false; |
| // We don't need to track IsWritten. If A is written to, return immediately. |
| |
| for (Use &U : A->uses()) { |
| if (Count++ >= 20) |
| return Attribute::None; |
| |
| Visited.insert(&U); |
| Worklist.push_back(&U); |
| } |
| |
| while (!Worklist.empty()) { |
| Use *U = Worklist.pop_back_val(); |
| Instruction *I = cast<Instruction>(U->getUser()); |
| Value *V = U->get(); |
| |
| switch (I->getOpcode()) { |
| case Instruction::BitCast: |
| case Instruction::GetElementPtr: |
| case Instruction::PHI: |
| case Instruction::Select: |
| case Instruction::AddrSpaceCast: |
| // The original value is not read/written via this if the new value isn't. |
| for (Use &UU : I->uses()) |
| if (Visited.insert(&UU).second) |
| Worklist.push_back(&UU); |
| break; |
| |
| case Instruction::Call: |
| case Instruction::Invoke: { |
| bool Captures = true; |
| |
| if (I->getType()->isVoidTy()) |
| Captures = false; |
| |
| auto AddUsersToWorklistIfCapturing = [&] { |
| if (Captures) |
| for (Use &UU : I->uses()) |
| if (Visited.insert(&UU).second) |
| Worklist.push_back(&UU); |
| }; |
| |
| CallSite CS(I); |
| if (CS.doesNotAccessMemory()) { |
| AddUsersToWorklistIfCapturing(); |
| continue; |
| } |
| |
| Function *F = CS.getCalledFunction(); |
| if (!F) { |
| if (CS.onlyReadsMemory()) { |
| IsRead = true; |
| AddUsersToWorklistIfCapturing(); |
| continue; |
| } |
| return Attribute::None; |
| } |
| |
| Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end(); |
| CallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end(); |
| for (CallSite::arg_iterator A = B; A != E; ++A, ++AI) { |
| if (A->get() == V) { |
| if (AI == AE) { |
| assert(F->isVarArg() && |
| "More params than args in non-varargs call."); |
| return Attribute::None; |
| } |
| Captures &= !CS.doesNotCapture(A - B); |
| if (SCCNodes.count(AI)) |
| continue; |
| if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(A - B)) |
| return Attribute::None; |
| if (!CS.doesNotAccessMemory(A - B)) |
| IsRead = true; |
| } |
| } |
| AddUsersToWorklistIfCapturing(); |
| break; |
| } |
| |
| case Instruction::Load: |
| IsRead = true; |
| break; |
| |
| case Instruction::ICmp: |
| case Instruction::Ret: |
| break; |
| |
| default: |
| return Attribute::None; |
| } |
| } |
| |
| return IsRead ? Attribute::ReadOnly : Attribute::ReadNone; |
| } |
| |
| /// AddArgumentAttrs - Deduce nocapture attributes for the SCC. |
| bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) { |
| bool Changed = false; |
| |
| SmallPtrSet<Function*, 8> SCCNodes; |
| |
| // Fill SCCNodes with the elements of the SCC. Used for quickly |
| // looking up whether a given CallGraphNode is in this SCC. |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| if (F && !F->isDeclaration() && !F->mayBeOverridden() && |
| !F->hasFnAttribute(Attribute::OptimizeNone)) |
| SCCNodes.insert(F); |
| } |
| |
| ArgumentGraph AG; |
| |
| AttrBuilder B; |
| B.addAttribute(Attribute::NoCapture); |
| |
| // Check each function in turn, determining which pointer arguments are not |
| // captured. |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| |
| if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) |
| // External node or function we're trying not to optimize - only a problem |
| // for arguments that we pass to it. |
| continue; |
| |
| // Definitions with weak linkage may be overridden at linktime with |
| // something that captures pointers, so treat them like declarations. |
| if (F->isDeclaration() || F->mayBeOverridden()) |
| continue; |
| |
| // Functions that are readonly (or readnone) and nounwind and don't return |
| // a value can't capture arguments. Don't analyze them. |
| if (F->onlyReadsMemory() && F->doesNotThrow() && |
| F->getReturnType()->isVoidTy()) { |
| for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); |
| A != E; ++A) { |
| if (A->getType()->isPointerTy() && !A->hasNoCaptureAttr()) { |
| A->addAttr(AttributeSet::get(F->getContext(), A->getArgNo() + 1, B)); |
| ++NumNoCapture; |
| Changed = true; |
| } |
| } |
| continue; |
| } |
| |
| for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); |
| A != E; ++A) { |
| if (!A->getType()->isPointerTy()) continue; |
| bool HasNonLocalUses = false; |
| if (!A->hasNoCaptureAttr()) { |
| ArgumentUsesTracker Tracker(SCCNodes); |
| PointerMayBeCaptured(A, &Tracker); |
| if (!Tracker.Captured) { |
| if (Tracker.Uses.empty()) { |
| // If it's trivially not captured, mark it nocapture now. |
| A->addAttr(AttributeSet::get(F->getContext(), A->getArgNo()+1, B)); |
| ++NumNoCapture; |
| Changed = true; |
| } else { |
| // If it's not trivially captured and not trivially not captured, |
| // then it must be calling into another function in our SCC. Save |
| // its particulars for Argument-SCC analysis later. |
| ArgumentGraphNode *Node = AG[A]; |
| for (SmallVectorImpl<Argument*>::iterator UI = Tracker.Uses.begin(), |
| UE = Tracker.Uses.end(); UI != UE; ++UI) { |
| Node->Uses.push_back(AG[*UI]); |
| if (*UI != A) |
| HasNonLocalUses = true; |
| } |
| } |
| } |
| // Otherwise, it's captured. Don't bother doing SCC analysis on it. |
| } |
| if (!HasNonLocalUses && !A->onlyReadsMemory()) { |
| // Can we determine that it's readonly/readnone without doing an SCC? |
| // Note that we don't allow any calls at all here, or else our result |
| // will be dependent on the iteration order through the functions in the |
| // SCC. |
| SmallPtrSet<Argument*, 8> Self; |
| Self.insert(A); |
| Attribute::AttrKind R = determinePointerReadAttrs(A, Self); |
| if (R != Attribute::None) { |
| AttrBuilder B; |
| B.addAttribute(R); |
| A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B)); |
| Changed = true; |
| R == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg; |
| } |
| } |
| } |
| } |
| |
| // The graph we've collected is partial because we stopped scanning for |
| // argument uses once we solved the argument trivially. These partial nodes |
| // show up as ArgumentGraphNode objects with an empty Uses list, and for |
| // these nodes the final decision about whether they capture has already been |
| // made. If the definition doesn't have a 'nocapture' attribute by now, it |
| // captures. |
| |
| for (scc_iterator<ArgumentGraph*> I = scc_begin(&AG); !I.isAtEnd(); ++I) { |
| const std::vector<ArgumentGraphNode *> &ArgumentSCC = *I; |
| if (ArgumentSCC.size() == 1) { |
| if (!ArgumentSCC[0]->Definition) continue; // synthetic root node |
| |
| // eg. "void f(int* x) { if (...) f(x); }" |
| if (ArgumentSCC[0]->Uses.size() == 1 && |
| ArgumentSCC[0]->Uses[0] == ArgumentSCC[0]) { |
| Argument *A = ArgumentSCC[0]->Definition; |
| A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B)); |
| ++NumNoCapture; |
| Changed = true; |
| } |
| continue; |
| } |
| |
| bool SCCCaptured = false; |
| for (auto I = ArgumentSCC.begin(), E = ArgumentSCC.end(); |
| I != E && !SCCCaptured; ++I) { |
| ArgumentGraphNode *Node = *I; |
| if (Node->Uses.empty()) { |
| if (!Node->Definition->hasNoCaptureAttr()) |
| SCCCaptured = true; |
| } |
| } |
| if (SCCCaptured) continue; |
| |
| SmallPtrSet<Argument*, 8> ArgumentSCCNodes; |
| // Fill ArgumentSCCNodes with the elements of the ArgumentSCC. Used for |
| // quickly looking up whether a given Argument is in this ArgumentSCC. |
| for (auto I = ArgumentSCC.begin(), E = ArgumentSCC.end(); I != E; ++I) { |
| ArgumentSCCNodes.insert((*I)->Definition); |
| } |
| |
| for (auto I = ArgumentSCC.begin(), E = ArgumentSCC.end(); |
| I != E && !SCCCaptured; ++I) { |
| ArgumentGraphNode *N = *I; |
| for (SmallVectorImpl<ArgumentGraphNode*>::iterator UI = N->Uses.begin(), |
| UE = N->Uses.end(); UI != UE; ++UI) { |
| Argument *A = (*UI)->Definition; |
| if (A->hasNoCaptureAttr() || ArgumentSCCNodes.count(A)) |
| continue; |
| SCCCaptured = true; |
| break; |
| } |
| } |
| if (SCCCaptured) continue; |
| |
| for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) { |
| Argument *A = ArgumentSCC[i]->Definition; |
| A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B)); |
| ++NumNoCapture; |
| Changed = true; |
| } |
| |
| // We also want to compute readonly/readnone. With a small number of false |
| // negatives, we can assume that any pointer which is captured isn't going |
| // to be provably readonly or readnone, since by definition we can't |
| // analyze all uses of a captured pointer. |
| // |
| // The false negatives happen when the pointer is captured by a function |
| // that promises readonly/readnone behaviour on the pointer, then the |
| // pointer's lifetime ends before anything that writes to arbitrary memory. |
| // Also, a readonly/readnone pointer may be returned, but returning a |
| // pointer is capturing it. |
| |
| Attribute::AttrKind ReadAttr = Attribute::ReadNone; |
| for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) { |
| Argument *A = ArgumentSCC[i]->Definition; |
| Attribute::AttrKind K = determinePointerReadAttrs(A, ArgumentSCCNodes); |
| if (K == Attribute::ReadNone) |
| continue; |
| if (K == Attribute::ReadOnly) { |
| ReadAttr = Attribute::ReadOnly; |
| continue; |
| } |
| ReadAttr = K; |
| break; |
| } |
| |
| if (ReadAttr != Attribute::None) { |
| AttrBuilder B; |
| B.addAttribute(ReadAttr); |
| for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) { |
| Argument *A = ArgumentSCC[i]->Definition; |
| A->addAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, B)); |
| ReadAttr == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg; |
| Changed = true; |
| } |
| } |
| } |
| |
| return Changed; |
| } |
| |
| /// IsFunctionMallocLike - A function is malloc-like if it returns either null |
| /// or a pointer that doesn't alias any other pointer visible to the caller. |
| bool FunctionAttrs::IsFunctionMallocLike(Function *F, |
| SmallPtrSet<Function*, 8> &SCCNodes) const { |
| SmallSetVector<Value *, 8> FlowsToReturn; |
| for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) |
| if (ReturnInst *Ret = dyn_cast<ReturnInst>(I->getTerminator())) |
| FlowsToReturn.insert(Ret->getReturnValue()); |
| |
| for (unsigned i = 0; i != FlowsToReturn.size(); ++i) { |
| Value *RetVal = FlowsToReturn[i]; |
| |
| if (Constant *C = dyn_cast<Constant>(RetVal)) { |
| if (!C->isNullValue() && !isa<UndefValue>(C)) |
| return false; |
| |
| continue; |
| } |
| |
| if (isa<Argument>(RetVal)) |
| return false; |
| |
| if (Instruction *RVI = dyn_cast<Instruction>(RetVal)) |
| switch (RVI->getOpcode()) { |
| // Extend the analysis by looking upwards. |
| case Instruction::BitCast: |
| case Instruction::GetElementPtr: |
| case Instruction::AddrSpaceCast: |
| FlowsToReturn.insert(RVI->getOperand(0)); |
| continue; |
| case Instruction::Select: { |
| SelectInst *SI = cast<SelectInst>(RVI); |
| FlowsToReturn.insert(SI->getTrueValue()); |
| FlowsToReturn.insert(SI->getFalseValue()); |
| continue; |
| } |
| case Instruction::PHI: { |
| PHINode *PN = cast<PHINode>(RVI); |
| for (int i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| FlowsToReturn.insert(PN->getIncomingValue(i)); |
| continue; |
| } |
| |
| // Check whether the pointer came from an allocation. |
| case Instruction::Alloca: |
| break; |
| case Instruction::Call: |
| case Instruction::Invoke: { |
| CallSite CS(RVI); |
| if (CS.paramHasAttr(0, Attribute::NoAlias)) |
| break; |
| if (CS.getCalledFunction() && |
| SCCNodes.count(CS.getCalledFunction())) |
| break; |
| } // fall-through |
| default: |
| return false; // Did not come from an allocation. |
| } |
| |
| if (PointerMayBeCaptured(RetVal, false, /*StoreCaptures=*/false)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /// AddNoAliasAttrs - Deduce noalias attributes for the SCC. |
| bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) { |
| SmallPtrSet<Function*, 8> SCCNodes; |
| |
| // Fill SCCNodes with the elements of the SCC. Used for quickly |
| // looking up whether a given CallGraphNode is in this SCC. |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) |
| SCCNodes.insert((*I)->getFunction()); |
| |
| // Check each function in turn, determining which functions return noalias |
| // pointers. |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| |
| if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) |
| // External node or node we don't want to optimize - skip it; |
| return false; |
| |
| // Already noalias. |
| if (F->doesNotAlias(0)) |
| continue; |
| |
| // Definitions with weak linkage may be overridden at linktime, so |
| // treat them like declarations. |
| if (F->isDeclaration() || F->mayBeOverridden()) |
| return false; |
| |
| // We annotate noalias return values, which are only applicable to |
| // pointer types. |
| if (!F->getReturnType()->isPointerTy()) |
| continue; |
| |
| if (!IsFunctionMallocLike(F, SCCNodes)) |
| return false; |
| } |
| |
| bool MadeChange = false; |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| if (F->doesNotAlias(0) || !F->getReturnType()->isPointerTy()) |
| continue; |
| |
| F->setDoesNotAlias(0); |
| ++NumNoAlias; |
| MadeChange = true; |
| } |
| |
| return MadeChange; |
| } |
| |
| /// inferPrototypeAttributes - Analyze the name and prototype of the |
| /// given function and set any applicable attributes. Returns true |
| /// if any attributes were set and false otherwise. |
| bool FunctionAttrs::inferPrototypeAttributes(Function &F) { |
| if (F.hasFnAttribute(Attribute::OptimizeNone)) |
| return false; |
| |
| FunctionType *FTy = F.getFunctionType(); |
| LibFunc::Func TheLibFunc; |
| if (!(TLI->getLibFunc(F.getName(), TheLibFunc) && TLI->has(TheLibFunc))) |
| return false; |
| |
| switch (TheLibFunc) { |
| case LibFunc::strlen: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setOnlyReadsMemory(F); |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::strchr: |
| case LibFunc::strrchr: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isIntegerTy()) |
| return false; |
| setOnlyReadsMemory(F); |
| setDoesNotThrow(F); |
| break; |
| case LibFunc::strtol: |
| case LibFunc::strtod: |
| case LibFunc::strtof: |
| case LibFunc::strtoul: |
| case LibFunc::strtoll: |
| case LibFunc::strtold: |
| case LibFunc::strtoull: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::strcpy: |
| case LibFunc::stpcpy: |
| case LibFunc::strcat: |
| case LibFunc::strncat: |
| case LibFunc::strncpy: |
| case LibFunc::stpncpy: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::strxfrm: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::strcmp: //0,1 |
| case LibFunc::strspn: // 0,1 |
| case LibFunc::strncmp: // 0,1 |
| case LibFunc::strcspn: //0,1 |
| case LibFunc::strcoll: //0,1 |
| case LibFunc::strcasecmp: // 0,1 |
| case LibFunc::strncasecmp: // |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setOnlyReadsMemory(F); |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::strstr: |
| case LibFunc::strpbrk: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setOnlyReadsMemory(F); |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::strtok: |
| case LibFunc::strtok_r: |
| if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::scanf: |
| if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::setbuf: |
| case LibFunc::setvbuf: |
| if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::strdup: |
| case LibFunc::strndup: |
| if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::stat: |
| case LibFunc::statvfs: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::sscanf: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::sprintf: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::snprintf: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(2)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 3); |
| setOnlyReadsMemory(F, 3); |
| break; |
| case LibFunc::setitimer: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(1)->isPointerTy() || |
| !FTy->getParamType(2)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| setDoesNotCapture(F, 3); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::system: |
| if (FTy->getNumParams() != 1 || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| // May throw; "system" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::malloc: |
| if (FTy->getNumParams() != 1 || |
| !FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| break; |
| case LibFunc::memcmp: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setOnlyReadsMemory(F); |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::memchr: |
| case LibFunc::memrchr: |
| if (FTy->getNumParams() != 3) |
| return false; |
| setOnlyReadsMemory(F); |
| setDoesNotThrow(F); |
| break; |
| case LibFunc::modf: |
| case LibFunc::modff: |
| case LibFunc::modfl: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::memcpy: |
| case LibFunc::memccpy: |
| case LibFunc::memmove: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::memalign: |
| if (!FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotAlias(F, 0); |
| break; |
| case LibFunc::mkdir: |
| if (FTy->getNumParams() == 0 || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::mktime: |
| if (FTy->getNumParams() == 0 || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::realloc: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::read: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| // May throw; "read" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::rewind: |
| if (FTy->getNumParams() < 1 || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::rmdir: |
| case LibFunc::remove: |
| case LibFunc::realpath: |
| if (FTy->getNumParams() < 1 || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::rename: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::readlink: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::write: |
| if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| // May throw; "write" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::bcopy: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::bcmp: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setOnlyReadsMemory(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::bzero: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::calloc: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| break; |
| case LibFunc::chmod: |
| case LibFunc::chown: |
| if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::ctermid: |
| case LibFunc::clearerr: |
| case LibFunc::closedir: |
| if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::atoi: |
| case LibFunc::atol: |
| case LibFunc::atof: |
| case LibFunc::atoll: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setOnlyReadsMemory(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::access: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::fopen: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::fdopen: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::feof: |
| case LibFunc::free: |
| case LibFunc::fseek: |
| case LibFunc::ftell: |
| case LibFunc::fgetc: |
| case LibFunc::fseeko: |
| case LibFunc::ftello: |
| case LibFunc::fileno: |
| case LibFunc::fflush: |
| case LibFunc::fclose: |
| case LibFunc::fsetpos: |
| case LibFunc::flockfile: |
| case LibFunc::funlockfile: |
| case LibFunc::ftrylockfile: |
| if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::ferror: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F); |
| break; |
| case LibFunc::fputc: |
| case LibFunc::fstat: |
| case LibFunc::frexp: |
| case LibFunc::frexpf: |
| case LibFunc::frexpl: |
| case LibFunc::fstatvfs: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::fgets: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(2)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 3); |
| break; |
| case LibFunc::fread: |
| if (FTy->getNumParams() != 4 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(3)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 4); |
| break; |
| case LibFunc::fwrite: |
| if (FTy->getNumParams() != 4 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(3)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 4); |
| break; |
| case LibFunc::fputs: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::fscanf: |
| case LibFunc::fprintf: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::fgetpos: |
| if (FTy->getNumParams() < 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::getc: |
| case LibFunc::getlogin_r: |
| case LibFunc::getc_unlocked: |
| if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::getenv: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setOnlyReadsMemory(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::gets: |
| case LibFunc::getchar: |
| setDoesNotThrow(F); |
| break; |
| case LibFunc::getitimer: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::getpwnam: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::ungetc: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::uname: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::unlink: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::unsetenv: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::utime: |
| case LibFunc::utimes: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::putc: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::puts: |
| case LibFunc::printf: |
| case LibFunc::perror: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::pread: |
| if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| // May throw; "pread" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::pwrite: |
| if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| // May throw; "pwrite" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::putchar: |
| setDoesNotThrow(F); |
| break; |
| case LibFunc::popen: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::pclose: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::vscanf: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::vsscanf: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(1)->isPointerTy() || |
| !FTy->getParamType(2)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::vfscanf: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(1)->isPointerTy() || |
| !FTy->getParamType(2)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::valloc: |
| if (!FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| break; |
| case LibFunc::vprintf: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::vfprintf: |
| case LibFunc::vsprintf: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::vsnprintf: |
| if (FTy->getNumParams() != 4 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(2)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 3); |
| setOnlyReadsMemory(F, 3); |
| break; |
| case LibFunc::open: |
| if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| // May throw; "open" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::opendir: |
| if (FTy->getNumParams() != 1 || |
| !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::tmpfile: |
| if (!FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| break; |
| case LibFunc::times: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::htonl: |
| case LibFunc::htons: |
| case LibFunc::ntohl: |
| case LibFunc::ntohs: |
| setDoesNotThrow(F); |
| setDoesNotAccessMemory(F); |
| break; |
| case LibFunc::lstat: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::lchown: |
| if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::qsort: |
| if (FTy->getNumParams() != 4 || !FTy->getParamType(3)->isPointerTy()) |
| return false; |
| // May throw; places call through function pointer. |
| setDoesNotCapture(F, 4); |
| break; |
| case LibFunc::dunder_strdup: |
| case LibFunc::dunder_strndup: |
| if (FTy->getNumParams() < 1 || |
| !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::dunder_strtok_r: |
| if (FTy->getNumParams() != 3 || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::under_IO_getc: |
| if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::under_IO_putc: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::dunder_isoc99_scanf: |
| if (FTy->getNumParams() < 1 || |
| !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::stat64: |
| case LibFunc::lstat64: |
| case LibFunc::statvfs64: |
| if (FTy->getNumParams() < 1 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::dunder_isoc99_sscanf: |
| if (FTy->getNumParams() < 1 || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::fopen64: |
| if (FTy->getNumParams() != 2 || |
| !FTy->getReturnType()->isPointerTy() || |
| !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| setOnlyReadsMemory(F, 1); |
| setOnlyReadsMemory(F, 2); |
| break; |
| case LibFunc::fseeko64: |
| case LibFunc::ftello64: |
| if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| break; |
| case LibFunc::tmpfile64: |
| if (!FTy->getReturnType()->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotAlias(F, 0); |
| break; |
| case LibFunc::fstat64: |
| case LibFunc::fstatvfs64: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 2); |
| break; |
| case LibFunc::open64: |
| if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy()) |
| return false; |
| // May throw; "open" is a valid pthread cancellation point. |
| setDoesNotCapture(F, 1); |
| setOnlyReadsMemory(F, 1); |
| break; |
| case LibFunc::gettimeofday: |
| if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy() || |
| !FTy->getParamType(1)->isPointerTy()) |
| return false; |
| // Currently some platforms have the restrict keyword on the arguments to |
| // gettimeofday. To be conservative, do not add noalias to gettimeofday's |
| // arguments. |
| setDoesNotThrow(F); |
| setDoesNotCapture(F, 1); |
| setDoesNotCapture(F, 2); |
| break; |
| default: |
| // Didn't mark any attributes. |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /// annotateLibraryCalls - Adds attributes to well-known standard library |
| /// call declarations. |
| bool FunctionAttrs::annotateLibraryCalls(const CallGraphSCC &SCC) { |
| bool MadeChange = false; |
| |
| // Check each function in turn annotating well-known library function |
| // declarations with attributes. |
| for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { |
| Function *F = (*I)->getFunction(); |
| |
| if (F && F->isDeclaration()) |
| MadeChange |= inferPrototypeAttributes(*F); |
| } |
| |
| return MadeChange; |
| } |
| |
| bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) { |
| AA = &getAnalysis<AliasAnalysis>(); |
| TLI = &getAnalysis<TargetLibraryInfo>(); |
| |
| bool Changed = annotateLibraryCalls(SCC); |
| Changed |= AddReadAttrs(SCC); |
| Changed |= AddArgumentAttrs(SCC); |
| Changed |= AddNoAliasAttrs(SCC); |
| return Changed; |
| } |
