llvm-project/llvm/lib/Transforms/IPO/FunctionAttrs.cpp

1346 lines
43 KiB
C++

//===- 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. 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.
// 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/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/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Target/TargetLibraryInfo.h"
using namespace llvm;
STATISTIC(NumReadNone, "Number of functions marked readnone");
STATISTIC(NumReadOnly, "Number of functions marked readonly");
STATISTIC(NumNoCapture, "Number of arguments marked nocapture");
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(0) {
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);
// 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 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);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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(CallGraph)
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 == 0)
// External node - may write memory. Just 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()) {
AliasAnalysis::Location Loc(Arg,
AliasAnalysis::UnknownSize,
I->getMetadata(LLVMContext::MD_tbaa));
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 = 0; }
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() { Captured = true; }
bool captured(Use *U) {
CallSite CS(U->getUser());
if (!CS.getInstruction()) { Captured = true; return true; }
Function *F = CS.getCalledFunction();
if (!F || !SCCNodes.count(F)) { Captured = true; return true; }
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);
break;
}
}
assert(!Uses.empty() && "Capturing call-site captured nothing?");
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();
}
};
}
/// AddNoCaptureAttrs - Deduce nocapture attributes for the SCC.
bool FunctionAttrs::AddNoCaptureAttrs(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())
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 - 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() && !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]);
}
}
// Otherwise, it's captured. Don't bother doing SCC analysis on it.
}
}
// 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), E = scc_end(&AG);
I != E; ++I) {
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]) {
ArgumentSCC[0]->
Definition->
addAttr(AttributeSet::get(ArgumentSCC[0]->Definition->getContext(),
ArgumentSCC[0]->Definition->getArgNo() + 1,
B));
++NumNoCapture;
Changed = true;
}
continue;
}
bool SCCCaptured = false;
for (std::vector<ArgumentGraphNode*>::iterator 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 (std::vector<ArgumentGraphNode*>::iterator I = ArgumentSCC.begin(),
E = ArgumentSCC.end(); I != E; ++I) {
ArgumentSCCNodes.insert((*I)->Definition);
}
for (std::vector<ArgumentGraphNode*>::iterator 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;
}
}
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:
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 == 0)
// External node - 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) {
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::strcpy:
case LibFunc::stpcpy:
case LibFunc::strcat:
case LibFunc::strtol:
case LibFunc::strtod:
case LibFunc::strtof:
case LibFunc::strtoul:
case LibFunc::strtoll:
case LibFunc::strtold:
case LibFunc::strncat:
case LibFunc::strncpy:
case LibFunc::stpncpy:
case LibFunc::strtoull:
if (FTy->getNumParams() < 2 ||
!FTy->getParamType(1)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(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);
break;
case LibFunc::strcmp:
case LibFunc::strspn:
case LibFunc::strncmp:
case LibFunc::strcspn:
case LibFunc::strcoll:
case LibFunc::strcasecmp:
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);
break;
case LibFunc::scanf:
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);
break;
case LibFunc::stat:
case LibFunc::sscanf:
case LibFunc::sprintf:
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);
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);
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);
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);
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:
case LibFunc::memcpy:
case LibFunc::memccpy:
case LibFunc::memmove:
if (FTy->getNumParams() < 2 ||
!FTy->getParamType(1)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
break;
case LibFunc::memalign:
if (!FTy->getReturnType()->isPointerTy())
return false;
setDoesNotAlias(F, 0);
break;
case LibFunc::mkdir:
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::rmdir:
case LibFunc::rewind:
case LibFunc::remove:
case LibFunc::realpath:
if (FTy->getNumParams() < 1 ||
!FTy->getParamType(0)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
break;
case LibFunc::rename:
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);
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);
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);
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:
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);
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);
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);
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);
case LibFunc::fread:
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);
case LibFunc::fputs:
case LibFunc::fscanf:
case LibFunc::fprintf:
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);
break;
case LibFunc::ungetc:
if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
break;
case LibFunc::uname:
case LibFunc::unlink:
case LibFunc::unsetenv:
if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(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);
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);
break;
case LibFunc::pread:
case LibFunc::pwrite:
if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy())
return false;
// May throw; these are valid pthread cancellation points.
setDoesNotCapture(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);
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);
break;
case LibFunc::vsscanf:
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);
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);
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);
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);
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);
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);
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);
break;
case LibFunc::lchown:
if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(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);
break;
case LibFunc::dunder_strtok_r:
if (FTy->getNumParams() != 3 ||
!FTy->getParamType(1)->isPointerTy())
return false;
setDoesNotThrow(F);
setDoesNotCapture(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);
break;
case LibFunc::stat64:
case LibFunc::lstat64:
case LibFunc::statvfs64:
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);
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);
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);
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 != 0 && 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 |= AddNoCaptureAttrs(SCC);
Changed |= AddNoAliasAttrs(SCC);
return Changed;
}