void SystemDependenceGraph::build()
{
boost::unordered_map<CFGVertex, Vertex> cfgVerticesToSdgVertices;
boost::unordered_map<SgNode*, Vertex> astNodesToSdgVertices;
//map<SgFunctionCallExp*, vector<SDGNode*> > funcCallToArgs;
vector<CallSiteInfo> functionCalls;
map<SgNode*, vector<Vertex> > actualInParameters;
map<SgNode*, vector<Vertex> > actualOutParameters;
map<SgNode*, Vertex> formalInParameters;
map<SgNode*, Vertex> formalOutParameters;
vector<SgFunctionDefinition*> funcDefs =
SageInterface::querySubTree<SgFunctionDefinition>(project_, V_SgFunctionDefinition);
foreach (SgFunctionDefinition* funcDef, funcDefs)
{
SgFunctionDeclaration* funcDecl = funcDef->get_declaration();
CFG* cfg = new CFG(funcDef, cfgNodefilter_);
functionsToCFGs_[funcDecl] = cfg;
// For each function, build an entry node for it.
SDGNode* entry = new SDGNode(SDGNode::Entry);
entry->astNode = funcDef;
//entry->funcDef = funcDef;
Vertex entryVertex = addVertex(entry);
functionsToEntries_[funcDecl] = entryVertex;
// Add all out formal parameters to SDG.
const SgInitializedNamePtrList& formalArgs = funcDecl->get_args();
foreach (SgInitializedName* initName, formalArgs)
{
// If the parameter is passed by reference, create a formal-out node.
if (isParaPassedByRef(initName->get_type()))
{
SDGNode* formalOutNode = new SDGNode(SDGNode::FormalOut);
formalOutNode->astNode = initName;
Vertex formalOutVertex = addVertex(formalOutNode);
formalOutParameters[initName] = formalOutVertex;
// Add a CD edge from call node to this formal-out node.
addTrueCDEdge(entryVertex, formalOutVertex);
}
}
// A vertex representing the returned value.
Vertex returnVertex;
// If the function returns something, build a formal-out node.
if (!isSgTypeVoid(funcDecl->get_type()->get_return_type()))
{
SDGNode* formalOutNode = new SDGNode(SDGNode::FormalOut);
// Assign the function declaration to the AST node of this vertex to make
// it possible to classify this node into the subgraph of this function.
formalOutNode->astNode = funcDecl;
returnVertex = addVertex(formalOutNode);
formalOutParameters[funcDecl] = returnVertex;
// Add a CD edge from call node to this formal-out node.
addTrueCDEdge(entryVertex, returnVertex);
}
// Add all CFG vertices to SDG.
foreach (CFGVertex cfgVertex, boost::vertices(*cfg))
{
if (cfgVertex == cfg->getEntry() || cfgVertex == cfg->getExit())
continue;
SgNode* astNode = (*cfg)[cfgVertex]->getNode();
// If this node is an initialized name and it is a parameter, make it
// as a formal in node.
SgInitializedName* initName = isSgInitializedName(astNode);
if (initName && isSgFunctionParameterList(initName->get_parent()))
{
SDGNode* formalInNode = new SDGNode(SDGNode::FormalIn);
formalInNode->astNode = initName;
Vertex formalInVertex = addVertex(formalInNode);
formalInParameters[initName] = formalInVertex;
cfgVerticesToSdgVertices[cfgVertex] = formalInVertex;
astNodesToSdgVertices[astNode] = formalInVertex;
// Add a CD edge from call node to this formal-in node.
addTrueCDEdge(entryVertex, formalInVertex);
continue;
}
// Add a new node to SDG.
SDGNode* newSdgNode = new SDGNode(SDGNode::ASTNode);
//newSdgNode->cfgNode = (*cfg)[cfgVertex];
newSdgNode->astNode = astNode;
Vertex sdgVertex = addVertex(newSdgNode);
cfgVerticesToSdgVertices[cfgVertex] = sdgVertex;
astNodesToSdgVertices[astNode] = sdgVertex;
// Connect a vertex containing the return statement to the formal-out return vertex.
if (isSgReturnStmt(astNode)
|| isSgReturnStmt(astNode->get_parent()))
{
SDGEdge* newEdge = new SDGEdge(SDGEdge::DataDependence);
addEdge(sdgVertex, returnVertex, newEdge);
}
// If this CFG node contains a function call expression, extract its all parameters
// and make them as actual-in nodes.
if (SgFunctionCallExp* funcCallExpr = isSgFunctionCallExp(astNode))
{
CallSiteInfo callInfo;
callInfo.funcCall = funcCallExpr;
callInfo.vertex = sdgVertex;
// Change the node type.
newSdgNode->type = SDGNode::FunctionCall;
vector<SDGNode*> argsNodes;
// Get the associated function declaration.
SgFunctionDeclaration* funcDecl = funcCallExpr->getAssociatedFunctionDeclaration();
if (funcDecl == NULL)
continue;
ROSE_ASSERT(funcDecl);
const SgInitializedNamePtrList& formalArgs = funcDecl->get_args();
SgExprListExp* args = funcCallExpr->get_args();
const SgExpressionPtrList& actualArgs = args->get_expressions();
if (formalArgs.size() != actualArgs.size())
{
cout << "The following function has variadic arguments:\n";
cout << funcDecl->get_file_info()->get_filename() << endl;
cout << funcDecl->get_name() << formalArgs.size() << " " << actualArgs.size() << endl;
continue;
}
for (int i = 0, s = actualArgs.size(); i < s; ++i)
{
// Make sure that this parameter node is added to SDG then we
// change its node type from normal AST node to a ActualIn arg.
ROSE_ASSERT(astNodesToSdgVertices.count(actualArgs[i]));
Vertex paraInVertex = astNodesToSdgVertices.at(actualArgs[i]);
SDGNode* paraInNode = (*this)[paraInVertex];
paraInNode->type = SDGNode::ActualIn;
actualInParameters[formalArgs[i]].push_back(paraInVertex);
callInfo.inPara.push_back(paraInVertex);
// Add a CD edge from call node to this actual-in node.
addTrueCDEdge(sdgVertex, paraInVertex);
// If the parameter is passed by reference, create a parameter-out node.
if (isParaPassedByRef(formalArgs[i]->get_type()))
{
SDGNode* paraOutNode = new SDGNode(SDGNode::ActualOut);
paraOutNode->astNode = actualArgs[i];
//argsNodes.push_back(paraInNode);
// Add an actual-out parameter node.
Vertex paraOutVertex = addVertex(paraOutNode);
actualOutParameters[formalArgs[i]].push_back(paraOutVertex);
callInfo.outPara.push_back(paraOutVertex);
// Add a CD edge from call node to this actual-out node.
addTrueCDEdge(sdgVertex, paraOutVertex);
}
}
if (!isSgTypeVoid(funcDecl->get_type()->get_return_type()))
{
// If this function returns a value, create a actual-out vertex.
SDGNode* paraOutNode = new SDGNode(SDGNode::ActualOut);
paraOutNode->astNode = funcCallExpr;
// Add an actual-out parameter node.
Vertex paraOutVertex = addVertex(paraOutNode);
actualOutParameters[funcDecl].push_back(paraOutVertex);
callInfo.outPara.push_back(paraOutVertex);
callInfo.isVoid = false;
callInfo.returned = paraOutVertex;
// Add a CD edge from call node to this actual-out node.
addTrueCDEdge(sdgVertex, paraOutVertex);
}
functionCalls.push_back(callInfo);
//funcCallToArgs[funcCallExpr] = argsNodes;
}
}
// Add control dependence edges.
addControlDependenceEdges(cfgVerticesToSdgVertices, *cfg, entryVertex);
}
/// \brief Check a function's CFG for thread-safety violations.
///
/// We traverse the blocks in the CFG, compute the set of mutexes that are held
/// at the end of each block, and issue warnings for thread safety violations.
/// Each block in the CFG is traversed exactly once.
void runThreadSafetyAnalysis(AnalysisContext &AC,
ThreadSafetyHandler &Handler) {
CFG *CFGraph = AC.getCFG();
if (!CFGraph) return;
const NamedDecl *D = dyn_cast_or_null<NamedDecl>(AC.getDecl());
if (!D)
return; // Ignore anonymous functions for now.
if (D->getAttr<NoThreadSafetyAnalysisAttr>())
return;
Lockset::Factory LocksetFactory;
// FIXME: Swith to SmallVector? Otherwise improve performance impact?
std::vector<Lockset> EntryLocksets(CFGraph->getNumBlockIDs(),
LocksetFactory.getEmptyMap());
std::vector<Lockset> ExitLocksets(CFGraph->getNumBlockIDs(),
LocksetFactory.getEmptyMap());
// We need to explore the CFG via a "topological" ordering.
// That way, we will be guaranteed to have information about required
// predecessor locksets when exploring a new block.
TopologicallySortedCFG SortedGraph(CFGraph);
CFGBlockSet VisitedBlocks(CFGraph);
if (!SortedGraph.empty() && D->hasAttrs()) {
const CFGBlock *FirstBlock = *SortedGraph.begin();
Lockset &InitialLockset = EntryLocksets[FirstBlock->getBlockID()];
const AttrVec &ArgAttrs = D->getAttrs();
for(unsigned i = 0; i < ArgAttrs.size(); ++i) {
Attr *Attr = ArgAttrs[i];
SourceLocation AttrLoc = Attr->getLocation();
if (SharedLocksRequiredAttr *SLRAttr
= dyn_cast<SharedLocksRequiredAttr>(Attr)) {
for (SharedLocksRequiredAttr::args_iterator
SLRIter = SLRAttr->args_begin(),
SLREnd = SLRAttr->args_end(); SLRIter != SLREnd; ++SLRIter)
InitialLockset = addLock(Handler, LocksetFactory, InitialLockset,
*SLRIter, D, LK_Shared,
AttrLoc);
} else if (ExclusiveLocksRequiredAttr *ELRAttr
= dyn_cast<ExclusiveLocksRequiredAttr>(Attr)) {
for (ExclusiveLocksRequiredAttr::args_iterator
ELRIter = ELRAttr->args_begin(),
ELREnd = ELRAttr->args_end(); ELRIter != ELREnd; ++ELRIter)
InitialLockset = addLock(Handler, LocksetFactory, InitialLockset,
*ELRIter, D, LK_Exclusive,
AttrLoc);
}
}
}
for (TopologicallySortedCFG::iterator I = SortedGraph.begin(),
E = SortedGraph.end(); I!= E; ++I) {
const CFGBlock *CurrBlock = *I;
int CurrBlockID = CurrBlock->getBlockID();
VisitedBlocks.insert(CurrBlock);
// Use the default initial lockset in case there are no predecessors.
Lockset &Entryset = EntryLocksets[CurrBlockID];
Lockset &Exitset = ExitLocksets[CurrBlockID];
// Iterate through the predecessor blocks and warn if the lockset for all
// predecessors is not the same. We take the entry lockset of the current
// block to be the intersection of all previous locksets.
// FIXME: By keeping the intersection, we may output more errors in future
// for a lock which is not in the intersection, but was in the union. We
// may want to also keep the union in future. As an example, let's say
// the intersection contains Mutex L, and the union contains L and M.
// Later we unlock M. At this point, we would output an error because we
// never locked M; although the real error is probably that we forgot to
// lock M on all code paths. Conversely, let's say that later we lock M.
// In this case, we should compare against the intersection instead of the
// union because the real error is probably that we forgot to unlock M on
// all code paths.
bool LocksetInitialized = false;
for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
PE = CurrBlock->pred_end(); PI != PE; ++PI) {
// if *PI -> CurrBlock is a back edge
if (*PI == 0 || !VisitedBlocks.alreadySet(*PI))
continue;
int PrevBlockID = (*PI)->getBlockID();
if (!LocksetInitialized) {
Entryset = ExitLocksets[PrevBlockID];
LocksetInitialized = true;
} else {
Entryset = intersectAndWarn(Handler, Entryset,
ExitLocksets[PrevBlockID], LocksetFactory,
LEK_LockedSomePredecessors);
}
}
BuildLockset LocksetBuilder(Handler, Entryset, LocksetFactory);
for (CFGBlock::const_iterator BI = CurrBlock->begin(),
BE = CurrBlock->end(); BI != BE; ++BI) {
if (const CFGStmt *CfgStmt = dyn_cast<CFGStmt>(&*BI))
LocksetBuilder.Visit(const_cast<Stmt*>(CfgStmt->getStmt()));
}
Exitset = LocksetBuilder.getLockset();
// For every back edge from CurrBlock (the end of the loop) to another block
// (FirstLoopBlock) we need to check that the Lockset of Block is equal to
// the one held at the beginning of FirstLoopBlock. We can look up the
// Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
SE = CurrBlock->succ_end(); SI != SE; ++SI) {
// if CurrBlock -> *SI is *not* a back edge
if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
continue;
CFGBlock *FirstLoopBlock = *SI;
Lockset PreLoop = EntryLocksets[FirstLoopBlock->getBlockID()];
Lockset LoopEnd = ExitLocksets[CurrBlockID];
intersectAndWarn(Handler, LoopEnd, PreLoop, LocksetFactory,
LEK_LockedSomeLoopIterations);
}
}
Lockset InitialLockset = EntryLocksets[CFGraph->getEntry().getBlockID()];
Lockset FinalLockset = ExitLocksets[CFGraph->getExit().getBlockID()];
// FIXME: Should we call this function for all blocks which exit the function?
intersectAndWarn(Handler, InitialLockset, FinalLockset, LocksetFactory,
LEK_LockedAtEndOfFunction);
}
/// CheckFallThrough - Check that we don't fall off the end of a
/// Statement that should return a value.
///
/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
/// MaybeFallThrough iff we might or might not fall off the end,
/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
/// return. We assume NeverFallThrough iff we never fall off the end of the
/// statement but we may return. We assume that functions not marked noreturn
/// will return.
static ControlFlowKind CheckFallThrough(AnalysisContext &AC) {
CFG *cfg = AC.getCFG();
if (cfg == 0) return UnknownFallThrough;
// The CFG leaves in dead things, and we don't want the dead code paths to
// confuse us, so we mark all live things first.
llvm::BitVector live(cfg->getNumBlockIDs());
unsigned count = reachable_code::ScanReachableFromBlock(cfg->getEntry(),
live);
bool AddEHEdges = AC.getAddEHEdges();
if (!AddEHEdges && count != cfg->getNumBlockIDs())
// When there are things remaining dead, and we didn't add EH edges
// from CallExprs to the catch clauses, we have to go back and
// mark them as live.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()]) {
if (b.pred_begin() == b.pred_end()) {
if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator()))
// When not adding EH edges from calls, catch clauses
// can otherwise seem dead. Avoid noting them as dead.
count += reachable_code::ScanReachableFromBlock(b, live);
continue;
}
}
}
// Now we know what is live, we check the live precessors of the exit block
// and look for fall through paths, being careful to ignore normal returns,
// and exceptional paths.
bool HasLiveReturn = false;
bool HasFakeEdge = false;
bool HasPlainEdge = false;
bool HasAbnormalEdge = false;
for (CFGBlock::pred_iterator I=cfg->getExit().pred_begin(),
E = cfg->getExit().pred_end();
I != E;
++I) {
CFGBlock& B = **I;
if (!live[B.getBlockID()])
continue;
if (B.size() == 0) {
if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
HasAbnormalEdge = true;
continue;
}
// A labeled empty statement, or the entry block...
HasPlainEdge = true;
continue;
}
Stmt *S = B[B.size()-1];
if (isa<ReturnStmt>(S)) {
HasLiveReturn = true;
continue;
}
if (isa<ObjCAtThrowStmt>(S)) {
HasFakeEdge = true;
continue;
}
if (isa<CXXThrowExpr>(S)) {
HasFakeEdge = true;
continue;
}
if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) {
if (AS->isMSAsm()) {
HasFakeEdge = true;
HasLiveReturn = true;
continue;
}
}
if (isa<CXXTryStmt>(S)) {
HasAbnormalEdge = true;
continue;
}
bool NoReturnEdge = false;
if (CallExpr *C = dyn_cast<CallExpr>(S)) {
if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
== B.succ_end()) {
HasAbnormalEdge = true;
continue;
}
Expr *CEE = C->getCallee()->IgnoreParenCasts();
if (getFunctionExtInfo(CEE->getType()).getNoReturn()) {
NoReturnEdge = true;
HasFakeEdge = true;
} else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) {
ValueDecl *VD = DRE->getDecl();
if (VD->hasAttr<NoReturnAttr>()) {
NoReturnEdge = true;
HasFakeEdge = true;
}
}
}
// FIXME: Remove this hack once temporaries and their destructors are
// modeled correctly by the CFG.
if (CXXExprWithTemporaries *E = dyn_cast<CXXExprWithTemporaries>(S)) {
for (unsigned I = 0, N = E->getNumTemporaries(); I != N; ++I) {
const FunctionDecl *FD = E->getTemporary(I)->getDestructor();
if (FD->hasAttr<NoReturnAttr>() ||
FD->getType()->getAs<FunctionType>()->getNoReturnAttr()) {
NoReturnEdge = true;
HasFakeEdge = true;
break;
}
}
}
// FIXME: Add noreturn message sends.
if (NoReturnEdge == false)
HasPlainEdge = true;
}
if (!HasPlainEdge) {
if (HasLiveReturn)
return NeverFallThrough;
return NeverFallThroughOrReturn;
}
if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
return MaybeFallThrough;
// This says AlwaysFallThrough for calls to functions that are not marked
// noreturn, that don't return. If people would like this warning to be more
// accurate, such functions should be marked as noreturn.
return AlwaysFallThrough;
}
/// CheckFallThrough - Check that we don't fall off the end of a
/// Statement that should return a value.
///
/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
/// MaybeFallThrough iff we might or might not fall off the end,
/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
/// return. We assume NeverFallThrough iff we never fall off the end of the
/// statement but we may return. We assume that functions not marked noreturn
/// will return.
static ControlFlowKind CheckFallThrough(AnalysisContext &AC) {
CFG *cfg = AC.getCFG();
if (cfg == 0) return UnknownFallThrough;
// The CFG leaves in dead things, and we don't want the dead code paths to
// confuse us, so we mark all live things first.
llvm::BitVector live(cfg->getNumBlockIDs());
unsigned count = reachable_code::ScanReachableFromBlock(cfg->getEntry(),
live);
bool AddEHEdges = AC.getAddEHEdges();
if (!AddEHEdges && count != cfg->getNumBlockIDs())
// When there are things remaining dead, and we didn't add EH edges
// from CallExprs to the catch clauses, we have to go back and
// mark them as live.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()]) {
if (b.pred_begin() == b.pred_end()) {
if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator()))
// When not adding EH edges from calls, catch clauses
// can otherwise seem dead. Avoid noting them as dead.
count += reachable_code::ScanReachableFromBlock(b, live);
continue;
}
}
}
// Now we know what is live, we check the live precessors of the exit block
// and look for fall through paths, being careful to ignore normal returns,
// and exceptional paths.
bool HasLiveReturn = false;
bool HasFakeEdge = false;
bool HasPlainEdge = false;
bool HasAbnormalEdge = false;
// Ignore default cases that aren't likely to be reachable because all
// enums in a switch(X) have explicit case statements.
CFGBlock::FilterOptions FO;
FO.IgnoreDefaultsWithCoveredEnums = 1;
for (CFGBlock::filtered_pred_iterator
I = cfg->getExit().filtered_pred_start_end(FO); I.hasMore(); ++I) {
const CFGBlock& B = **I;
if (!live[B.getBlockID()])
continue;
// Destructors can appear after the 'return' in the CFG. This is
// normal. We need to look pass the destructors for the return
// statement (if it exists).
CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
bool hasNoReturnDtor = false;
for ( ; ri != re ; ++ri) {
CFGElement CE = *ri;
// FIXME: The right solution is to just sever the edges in the
// CFG itself.
if (const CFGImplicitDtor *iDtor = ri->getAs<CFGImplicitDtor>())
if (iDtor->isNoReturn(AC.getASTContext())) {
hasNoReturnDtor = true;
HasFakeEdge = true;
break;
}
if (isa<CFGStmt>(CE))
break;
}
if (hasNoReturnDtor)
continue;
// No more CFGElements in the block?
if (ri == re) {
if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
HasAbnormalEdge = true;
continue;
}
// A labeled empty statement, or the entry block...
HasPlainEdge = true;
continue;
}
CFGStmt CS = cast<CFGStmt>(*ri);
Stmt *S = CS.getStmt();
if (isa<ReturnStmt>(S)) {
HasLiveReturn = true;
continue;
}
if (isa<ObjCAtThrowStmt>(S)) {
HasFakeEdge = true;
continue;
}
if (isa<CXXThrowExpr>(S)) {
HasFakeEdge = true;
continue;
}
if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) {
if (AS->isMSAsm()) {
HasFakeEdge = true;
HasLiveReturn = true;
continue;
}
}
if (isa<CXXTryStmt>(S)) {
HasAbnormalEdge = true;
continue;
}
bool NoReturnEdge = false;
if (CallExpr *C = dyn_cast<CallExpr>(S)) {
if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
== B.succ_end()) {
HasAbnormalEdge = true;
continue;
}
Expr *CEE = C->getCallee()->IgnoreParenCasts();
QualType calleeType = CEE->getType();
if (calleeType == AC.getASTContext().BoundMemberTy) {
calleeType = Expr::findBoundMemberType(CEE);
assert(!calleeType.isNull() && "analyzing unresolved call?");
}
if (getFunctionExtInfo(calleeType).getNoReturn()) {
NoReturnEdge = true;
HasFakeEdge = true;
} else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) {
ValueDecl *VD = DRE->getDecl();
if (VD->hasAttr<NoReturnAttr>()) {
NoReturnEdge = true;
HasFakeEdge = true;
}
}
}
// FIXME: Add noreturn message sends.
if (NoReturnEdge == false)
HasPlainEdge = true;
}
if (!HasPlainEdge) {
if (HasLiveReturn)
return NeverFallThrough;
return NeverFallThroughOrReturn;
}
if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
return MaybeFallThrough;
// This says AlwaysFallThrough for calls to functions that are not marked
// noreturn, that don't return. If people would like this warning to be more
// accurate, such functions should be marked as noreturn.
return AlwaysFallThrough;
}
