X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FTransforms%2FIPO%2FFunctionAttrs.cpp;h=6c357ed03a805be0b5a8d6c5928417dce7da2a01;hp=d464e2ee8259482cfb1d5e4f00bbe872c01efe3f;hb=59991f96f9c522f456d9cb6d2eda4a226806d7ff;hpb=391f5bce046e229a8d52faf317a7ab980aff0dbb diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp index d464e2ee825..6c357ed03a8 100644 --- a/lib/Transforms/IPO/FunctionAttrs.cpp +++ b/lib/Transforms/IPO/FunctionAttrs.cpp @@ -1,4 +1,4 @@ -//===- FunctionAttrs.cpp - Pass which marks functions readnone or readonly ===// +//===- FunctionAttrs.cpp - Pass which marks functions attributes ----------===// // // The LLVM Compiler Infrastructure // @@ -9,126 +9,204 @@ // // 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. In addition, -// it marks function arguments (of pointer type) 'nocapture' if a call -// to the function does not create any copies of the pointer value that -// outlive the call. This more or less means that the pointer is only -// dereferenced, and not returned from the function or stored in a global. -// This pass is implemented as a bottom-up traversal of the call-graph. +// 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. // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "functionattrs" #include "llvm/Transforms/IPO.h" -#include "llvm/CallGraphSCCPass.h" -#include "llvm/GlobalVariable.h" -#include "llvm/IntrinsicInst.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/AssumptionCache.h" +#include "llvm/Analysis/BasicAliasAnalysis.h" #include "llvm/Analysis/CallGraph.h" +#include "llvm/Analysis/CallGraphSCCPass.h" #include "llvm/Analysis/CaptureTracking.h" -#include "llvm/ADT/SmallSet.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/UniqueVector.h" -#include "llvm/Support/InstIterator.h" +#include "llvm/Analysis/TargetLibraryInfo.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/InstIterator.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Analysis/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(NumNonNullReturn, "Number of function returns marked nonnull"); +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) { - initializeFunctionAttrsPass(*PassRegistry::getPassRegistry()); - } - - // runOnSCC - Analyze the SCC, performing the transformation if possible. - bool runOnSCC(CallGraphSCC &SCC); - - // AddReadAttrs - Deduce readonly/readnone attributes for the SCC. - bool AddReadAttrs(const CallGraphSCC &SCC); - - // AddNoCaptureAttrs - Deduce nocapture attributes for the SCC. - bool AddNoCaptureAttrs(const CallGraphSCC &SCC); +struct FunctionAttrs : public CallGraphSCCPass { + static char ID; // Pass identification, replacement for typeid + FunctionAttrs() : CallGraphSCCPass(ID) { + initializeFunctionAttrsPass(*PassRegistry::getPassRegistry()); + } - // IsFunctionMallocLike - Does this function allocate new memory? - bool IsFunctionMallocLike(Function *F, - SmallPtrSet &) const; + bool runOnSCC(CallGraphSCC &SCC) override; - // AddNoAliasAttrs - Deduce noalias attributes for the SCC. - bool AddNoAliasAttrs(const CallGraphSCC &SCC); + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.setPreservesCFG(); + AU.addRequired(); + AU.addRequired(); + CallGraphSCCPass::getAnalysisUsage(AU); + } - virtual void getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesCFG(); - CallGraphSCCPass::getAnalysisUsage(AU); - } +private: + TargetLibraryInfo *TLI; - bool PointsToLocalOrConstantMemory(Value *V); - }; + bool AddReadAttrs(const CallGraphSCC &SCC); + bool AddArgumentAttrs(const CallGraphSCC &SCC); + bool AddNoAliasAttrs(const CallGraphSCC &SCC); + bool AddNonNullAttrs(const CallGraphSCC &SCC); + bool annotateLibraryCalls(const CallGraphSCC &SCC); +}; } char FunctionAttrs::ID = 0; INITIALIZE_PASS_BEGIN(FunctionAttrs, "functionattrs", - "Deduce function attributes", false, false) -INITIALIZE_AG_DEPENDENCY(CallGraph) + "Deduce function attributes", false, false) +INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) +INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass) +INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass) INITIALIZE_PASS_END(FunctionAttrs, "functionattrs", - "Deduce function attributes", false, false) + "Deduce function attributes", false, false) Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); } +namespace { +/// The three kinds of memory access relevant to 'readonly' and +/// 'readnone' attributes. +enum MemoryAccessKind { + MAK_ReadNone = 0, + MAK_ReadOnly = 1, + MAK_MayWrite = 2 +}; +} -/// PointsToLocalOrConstantMemory - Returns whether the given pointer value -/// points to memory that is local to the function, with global constants being -/// considered local to all functions. -bool FunctionAttrs::PointsToLocalOrConstantMemory(Value *V) { - SmallVector Worklist; - unsigned MaxLookup = 8; +static MemoryAccessKind +checkFunctionMemoryAccess(Function &F, AAResults &AAR, + const SmallPtrSetImpl &SCCNodes) { + FunctionModRefBehavior MRB = AAR.getModRefBehavior(&F); + if (MRB == FMRB_DoesNotAccessMemory) + // Already perfect! + return MAK_ReadNone; + + // 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)) + return MAK_ReadOnly; + + // Conservatively assume it writes to memory. + return MAK_MayWrite; + } - Worklist.push_back(V); + // Scan the function body for instructions that may read or write memory. + bool ReadsMemory = false; + 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(I)); + if (CS) { + // Ignore calls to functions in the same SCC. + if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction())) + continue; + FunctionModRefBehavior MRB = AAR.getModRefBehavior(CS); + + // If the call doesn't access memory, we're done. + if (!(MRB & MRI_ModRef)) + continue; + + if (!AliasAnalysis::onlyAccessesArgPointees(MRB)) { + // The call could access any memory. If that includes writes, give up. + if (MRB & MRI_Mod) + return MAK_MayWrite; + // If it reads, note it. + if (MRB & MRI_Ref) + ReadsMemory = true; + continue; + } - do { - V = Worklist.pop_back_val()->getUnderlyingObject(); + // 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()) + continue; - // An alloca instruction defines local memory. - if (isa(V)) - continue; + AAMDNodes AAInfo; + I->getAAMetadata(AAInfo); + MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo); - // A global constant counts as local memory for our purposes. - if (GlobalVariable *GV = dyn_cast(V)) { - if (!GV->isConstant()) - return false; - continue; - } + // Skip accesses to local or constant memory as they don't impact the + // externally visible mod/ref behavior. + if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true)) + continue; - // If both select values point to local memory, then so does the select. - if (SelectInst *SI = dyn_cast(V)) { - Worklist.push_back(SI->getTrueValue()); - Worklist.push_back(SI->getFalseValue()); + if (MRB & MRI_Mod) + // Writes non-local memory. Give up. + return MAK_MayWrite; + if (MRB & MRI_Ref) + // Ok, it reads non-local memory. + ReadsMemory = true; + } continue; + } else if (LoadInst *LI = dyn_cast(I)) { + // Ignore non-volatile loads from local memory. (Atomic is okay here.) + if (!LI->isVolatile()) { + MemoryLocation Loc = MemoryLocation::get(LI); + if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true)) + continue; + } + } else if (StoreInst *SI = dyn_cast(I)) { + // Ignore non-volatile stores to local memory. (Atomic is okay here.) + if (!SI->isVolatile()) { + MemoryLocation Loc = MemoryLocation::get(SI); + if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true)) + continue; + } + } else if (VAArgInst *VI = dyn_cast(I)) { + // Ignore vaargs on local memory. + MemoryLocation Loc = MemoryLocation::get(VI); + if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true)) + continue; } - // If all values incoming to a phi node point to local memory, then so does - // the phi. - if (PHINode *PN = dyn_cast(V)) { - // Don't bother inspecting phi nodes with many operands. - if (PN->getNumIncomingValues() > MaxLookup) - return false; - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) - Worklist.push_back(PN->getIncomingValue(i)); - 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 MAK_MayWrite; - return false; - } while (!Worklist.empty() && --MaxLookup); + // If this instruction may read memory, remember that. + ReadsMemory |= I->mayReadFromMemory(); + } - return Worklist.empty(); + return ReadsMemory ? MAK_ReadOnly : MAK_ReadNone; } -/// AddReadAttrs - Deduce readonly/readnone attributes for the SCC. +/// Deduce readonly/readnone attributes for the SCC. bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) { - SmallPtrSet SCCNodes; + SmallPtrSet SCCNodes; // Fill SCCNodes with the elements of the SCC. Used for quickly // looking up whether a given CallGraphNode is in this SCC. @@ -141,72 +219,28 @@ bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) { for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { Function *F = (*I)->getFunction(); - if (F == 0) - // External node - may write memory. Just give up. + 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; - if (F->doesNotAccessMemory()) - // Already perfect! - continue; + // We need to manually construct BasicAA directly in order to disable its + // use of other function analyses. + BasicAAResult BAR(createLegacyPMBasicAAResult(*this, *F)); - // 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 (!F->onlyReadsMemory()) - // May write memory. Just give up. - return false; + // Construct our own AA results for this function. We do this manually to + // work around the limitations of the legacy pass manager. + AAResults AAR(createLegacyPMAAResults(*this, *F, BAR)); + switch (checkFunctionMemoryAccess(*F, AAR, SCCNodes)) { + case MAK_MayWrite: + return false; + case MAK_ReadOnly: 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(I)); - if (CS && CS.getCalledFunction()) { - // Ignore calls to functions in the same SCC. - if (SCCNodes.count(CS.getCalledFunction())) - continue; - // Ignore intrinsics that only access local memory. - if (unsigned id = CS.getCalledFunction()->getIntrinsicID()) - if (AliasAnalysis::getIntrinsicModRefBehavior(id) == - AliasAnalysis::AccessesArguments) { - // Check that all pointer arguments point to local memory. - for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end(); - CI != CE; ++CI) { - Value *Arg = *CI; - if (Arg->getType()->isPointerTy() && - !PointsToLocalOrConstantMemory(Arg)) - // Writes memory. Just give up. - return false; - } - // Only reads and writes local memory. - continue; - } - } else if (LoadInst *LI = dyn_cast(I)) { - // Ignore non-volatile loads from local memory. - if (!LI->isVolatile() && - PointsToLocalOrConstantMemory(LI->getPointerOperand())) - continue; - } else if (StoreInst *SI = dyn_cast(I)) { - // Ignore non-volatile stores to local memory. - if (!SI->isVolatile() && - PointsToLocalOrConstantMemory(SI->getPointerOperand())) - 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(); + break; + case MAK_ReadNone: + // Nothing to do! + break; } } @@ -227,10 +261,15 @@ bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) { MadeChange = true; // Clear out any existing attributes. - F->removeAttribute(~0, Attribute::ReadOnly | Attribute::ReadNone); + 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(~0, ReadsMemory? Attribute::ReadOnly : Attribute::ReadNone); + F->addAttribute(AttributeSet::FunctionIndex, + ReadsMemory ? Attribute::ReadOnly : Attribute::ReadNone); if (ReadsMemory) ++NumReadOnly; @@ -241,47 +280,449 @@ bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) { return MadeChange; } -/// AddNoCaptureAttrs - Deduce nocapture attributes for the SCC. -bool FunctionAttrs::AddNoCaptureAttrs(const CallGraphSCC &SCC) { +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 Uses; +}; + +class ArgumentGraph { + // We store pointers to ArgumentGraphNode objects, so it's important that + // that they not move around upon insert. + typedef std::map 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::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 &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 Uses; // Uses within our SCC. + + const SmallPtrSet &SCCNodes; +}; +} + +namespace llvm { +template <> struct GraphTraits { + typedef ArgumentGraphNode NodeType; + typedef SmallVectorImpl::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 : public GraphTraits { + 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 &SCCNodes) { + + SmallVector Worklist; + SmallSet Visited; + + // 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()) { + Visited.insert(&U); + Worklist.push_back(&U); + } + + while (!Worklist.empty()) { + Use *U = Worklist.pop_back_val(); + Instruction *I = cast(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; +} + +/// Deduce nocapture attributes for the SCC. +bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) { bool Changed = false; + SmallPtrSet 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 == 0) - // External node - skip it; + 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 writes memory, so treat them like declarations. + // something that captures pointers, so treat them like declarations. if (F->isDeclaration() || F->mayBeOverridden()) continue; - for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); A!=E; ++A) - if (A->getType()->isPointerTy() && !A->hasNoCaptureAttr() && - !PointerMayBeCaptured(A, true, /*StoreCaptures=*/false)) { - A->addAttr(Attribute::NoCapture); + // 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::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 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 I = scc_begin(&AG); !I.isAtEnd(); ++I) { + const std::vector &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 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::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, R; + B.addAttribute(ReadAttr); + R.addAttribute(Attribute::ReadOnly).addAttribute(Attribute::ReadNone); + for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) { + Argument *A = ArgumentSCC[i]->Definition; + // Clear out existing readonly/readnone attributes + A->removeAttr(AttributeSet::get(A->getContext(), A->getArgNo() + 1, R)); + 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 &SCCNodes) const { - UniqueVector FlowsToReturn; +/// Tests whether a function is "malloc-like". +/// +/// A function is "malloc-like" if it returns either null or a pointer that +/// doesn't alias any other pointer visible to the caller. +static bool isFunctionMallocLike(Function *F, + SmallPtrSet &SCCNodes) { + SmallSetVector FlowsToReturn; for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) if (ReturnInst *Ret = dyn_cast(I->getTerminator())) FlowsToReturn.insert(Ret->getReturnValue()); for (unsigned i = 0; i != FlowsToReturn.size(); ++i) { - Value *RetVal = FlowsToReturn[i+1]; // UniqueVector[0] is reserved. + Value *RetVal = FlowsToReturn[i]; if (Constant *C = dyn_cast(RetVal)) { if (!C->isNullValue() && !isa(C)) @@ -295,38 +736,38 @@ bool FunctionAttrs::IsFunctionMallocLike(Function *F, if (Instruction *RVI = dyn_cast(RetVal)) switch (RVI->getOpcode()) { - // Extend the analysis by looking upwards. - case Instruction::BitCast: - case Instruction::GetElementPtr: - FlowsToReturn.insert(RVI->getOperand(0)); - continue; - case Instruction::Select: { - SelectInst *SI = cast(RVI); - FlowsToReturn.insert(SI->getTrueValue()); - FlowsToReturn.insert(SI->getFalseValue()); - continue; - } - case Instruction::PHI: { - PHINode *PN = cast(RVI); - for (int i = 0, e = PN->getNumIncomingValues(); i != e; ++i) - FlowsToReturn.insert(PN->getIncomingValue(i)); - continue; - } + // 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(RVI); + FlowsToReturn.insert(SI->getTrueValue()); + FlowsToReturn.insert(SI->getFalseValue()); + continue; + } + case Instruction::PHI: { + PHINode *PN = cast(RVI); + for (Value *IncValue : PN->incoming_values()) + FlowsToReturn.insert(IncValue); + continue; + } - // Check whether the pointer came from an allocation. - case Instruction::Alloca: + // 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; - 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 (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction())) + break; + } // fall-through + default: + return false; // Did not come from an allocation. } if (PointerMayBeCaptured(RetVal, false, /*StoreCaptures=*/false)) @@ -336,9 +777,9 @@ bool FunctionAttrs::IsFunctionMallocLike(Function *F, return true; } -/// AddNoAliasAttrs - Deduce noalias attributes for the SCC. +/// Deduce noalias attributes for the SCC. bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) { - SmallPtrSet SCCNodes; + SmallPtrSet SCCNodes; // Fill SCCNodes with the elements of the SCC. Used for quickly // looking up whether a given CallGraphNode is in this SCC. @@ -350,8 +791,8 @@ bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) { for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { Function *F = (*I)->getFunction(); - if (F == 0) - // External node - skip it; + if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) + // External node or node we don't want to optimize - skip it; return false; // Already noalias. @@ -363,12 +804,12 @@ bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) { if (F->isDeclaration() || F->mayBeOverridden()) return false; - // We annotate noalias return values, which are only applicable to + // We annotate noalias return values, which are only applicable to // pointer types. if (!F->getReturnType()->isPointerTy()) continue; - if (!IsFunctionMallocLike(F, SCCNodes)) + if (!isFunctionMallocLike(F, SCCNodes)) return false; } @@ -386,9 +827,1018 @@ bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) { return MadeChange; } +/// Tests whether this function is known to not return null. +/// +/// Requires that the function returns a pointer. +/// +/// Returns true if it believes the function will not return a null, and sets +/// \p Speculative based on whether the returned conclusion is a speculative +/// conclusion due to SCC calls. +static bool isReturnNonNull(Function *F, SmallPtrSet &SCCNodes, + const TargetLibraryInfo &TLI, bool &Speculative) { + assert(F->getReturnType()->isPointerTy() && + "nonnull only meaningful on pointer types"); + Speculative = false; + + SmallSetVector FlowsToReturn; + for (BasicBlock &BB : *F) + if (auto *Ret = dyn_cast(BB.getTerminator())) + FlowsToReturn.insert(Ret->getReturnValue()); + + for (unsigned i = 0; i != FlowsToReturn.size(); ++i) { + Value *RetVal = FlowsToReturn[i]; + + // If this value is locally known to be non-null, we're good + if (isKnownNonNull(RetVal, &TLI)) + continue; + + // Otherwise, we need to look upwards since we can't make any local + // conclusions. + Instruction *RVI = dyn_cast(RetVal); + if (!RVI) + return false; + 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(RVI); + FlowsToReturn.insert(SI->getTrueValue()); + FlowsToReturn.insert(SI->getFalseValue()); + continue; + } + case Instruction::PHI: { + PHINode *PN = cast(RVI); + for (int i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + FlowsToReturn.insert(PN->getIncomingValue(i)); + continue; + } + case Instruction::Call: + case Instruction::Invoke: { + CallSite CS(RVI); + Function *Callee = CS.getCalledFunction(); + // A call to a node within the SCC is assumed to return null until + // proven otherwise + if (Callee && SCCNodes.count(Callee)) { + Speculative = true; + continue; + } + return false; + } + default: + return false; // Unknown source, may be null + }; + llvm_unreachable("should have either continued or returned"); + } + + return true; +} + +/// Deduce nonnull attributes for the SCC. +bool FunctionAttrs::AddNonNullAttrs(const CallGraphSCC &SCC) { + SmallPtrSet 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()); + + // Speculative that all functions in the SCC return only nonnull + // pointers. We may refute this as we analyze functions. + bool SCCReturnsNonNull = true; + + bool MadeChange = false; + + // Check each function in turn, determining which functions return nonnull + // 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 nonnull. + if (F->getAttributes().hasAttribute(AttributeSet::ReturnIndex, + Attribute::NonNull)) + continue; + + // Definitions with weak linkage may be overridden at linktime, so + // treat them like declarations. + if (F->isDeclaration() || F->mayBeOverridden()) + return false; + + // We annotate nonnull return values, which are only applicable to + // pointer types. + if (!F->getReturnType()->isPointerTy()) + continue; + + bool Speculative = false; + if (isReturnNonNull(F, SCCNodes, *TLI, Speculative)) { + if (!Speculative) { + // Mark the function eagerly since we may discover a function + // which prevents us from speculating about the entire SCC + DEBUG(dbgs() << "Eagerly marking " << F->getName() << " as nonnull\n"); + F->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull); + ++NumNonNullReturn; + MadeChange = true; + } + continue; + } + // At least one function returns something which could be null, can't + // speculate any more. + SCCReturnsNonNull = false; + } + + if (SCCReturnsNonNull) { + for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { + Function *F = (*I)->getFunction(); + if (F->getAttributes().hasAttribute(AttributeSet::ReturnIndex, + Attribute::NonNull) || + !F->getReturnType()->isPointerTy()) + continue; + + DEBUG(dbgs() << "SCC marking " << F->getName() << " as nonnull\n"); + F->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull); + ++NumNonNullReturn; + MadeChange = true; + } + } + + return MadeChange; +} + +static void setDoesNotAccessMemory(Function &F) { + if (!F.doesNotAccessMemory()) { + F.setDoesNotAccessMemory(); + ++NumAnnotated; + } +} + +static void setOnlyReadsMemory(Function &F) { + if (!F.onlyReadsMemory()) { + F.setOnlyReadsMemory(); + ++NumAnnotated; + } +} + +static void setDoesNotThrow(Function &F) { + if (!F.doesNotThrow()) { + F.setDoesNotThrow(); + ++NumAnnotated; + } +} + +static void setDoesNotCapture(Function &F, unsigned n) { + if (!F.doesNotCapture(n)) { + F.setDoesNotCapture(n); + ++NumAnnotated; + } +} + +static void setOnlyReadsMemory(Function &F, unsigned n) { + if (!F.onlyReadsMemory(n)) { + F.setOnlyReadsMemory(n); + ++NumAnnotated; + } +} + +static void setDoesNotAlias(Function &F, unsigned n) { + if (!F.doesNotAlias(n)) { + F.setDoesNotAlias(n); + ++NumAnnotated; + } +} + +/// Analyze the name and prototype of the given function and set any applicable +/// attributes. +/// +/// Returns true if any attributes were set and false otherwise. +static bool inferPrototypeAttributes(Function &F, const TargetLibraryInfo &TLI) { + 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; +} + +/// 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, *TLI); + } + + return MadeChange; +} + bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) { - bool Changed = AddReadAttrs(SCC); - Changed |= AddNoCaptureAttrs(SCC); + TLI = &getAnalysis().getTLI(); + + bool Changed = annotateLibraryCalls(SCC); + Changed |= AddReadAttrs(SCC); + Changed |= AddArgumentAttrs(SCC); Changed |= AddNoAliasAttrs(SCC); + Changed |= AddNonNullAttrs(SCC); return Changed; }