1 //===- ThreadSafety.cpp ----------------------------------------*- C++ --*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // A intra-procedural analysis for thread safety (e.g. deadlocks and race
11 // conditions), based off of an annotation system.
12 //
13 // See http://clang.llvm.org/docs/ThreadSafetyAnalysis.html
14 // for more information.
15 //
16 //===----------------------------------------------------------------------===//
17
18 #include "clang/AST/Attr.h"
19 #include "clang/AST/DeclCXX.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/StmtCXX.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "clang/Analysis/Analyses/PostOrderCFGView.h"
24 #include "clang/Analysis/Analyses/ThreadSafety.h"
25 #include "clang/Analysis/Analyses/ThreadSafetyCommon.h"
26 #include "clang/Analysis/Analyses/ThreadSafetyLogical.h"
27 #include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
28 #include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
29 #include "clang/Analysis/AnalysisContext.h"
30 #include "clang/Analysis/CFG.h"
31 #include "clang/Analysis/CFGStmtMap.h"
32 #include "clang/Basic/OperatorKinds.h"
33 #include "clang/Basic/SourceLocation.h"
34 #include "clang/Basic/SourceManager.h"
35 #include "llvm/ADT/BitVector.h"
36 #include "llvm/ADT/FoldingSet.h"
37 #include "llvm/ADT/ImmutableMap.h"
38 #include "llvm/ADT/PostOrderIterator.h"
39 #include "llvm/ADT/SmallVector.h"
40 #include "llvm/ADT/StringRef.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include <algorithm>
43 #include <ostream>
44 #include <sstream>
45 #include <utility>
46 #include <vector>
47 using namespace clang;
48 using namespace threadSafety;
49
50 // Key method definition
~ThreadSafetyHandler()51 ThreadSafetyHandler::~ThreadSafetyHandler() {}
52
53 namespace {
54 class TILPrinter :
55 public til::PrettyPrinter<TILPrinter, llvm::raw_ostream> {};
56
57
58 /// Issue a warning about an invalid lock expression
warnInvalidLock(ThreadSafetyHandler & Handler,const Expr * MutexExp,const NamedDecl * D,const Expr * DeclExp,StringRef Kind)59 static void warnInvalidLock(ThreadSafetyHandler &Handler,
60 const Expr *MutexExp, const NamedDecl *D,
61 const Expr *DeclExp, StringRef Kind) {
62 SourceLocation Loc;
63 if (DeclExp)
64 Loc = DeclExp->getExprLoc();
65
66 // FIXME: add a note about the attribute location in MutexExp or D
67 if (Loc.isValid())
68 Handler.handleInvalidLockExp(Kind, Loc);
69 }
70
71 /// \brief A set of CapabilityInfo objects, which are compiled from the
72 /// requires attributes on a function.
73 class CapExprSet : public SmallVector<CapabilityExpr, 4> {
74 public:
75 /// \brief Push M onto list, but discard duplicates.
push_back_nodup(const CapabilityExpr & CapE)76 void push_back_nodup(const CapabilityExpr &CapE) {
77 iterator It = std::find_if(begin(), end(),
78 [=](const CapabilityExpr &CapE2) {
79 return CapE.equals(CapE2);
80 });
81 if (It == end())
82 push_back(CapE);
83 }
84 };
85
86 class FactManager;
87 class FactSet;
88
89 /// \brief This is a helper class that stores a fact that is known at a
90 /// particular point in program execution. Currently, a fact is a capability,
91 /// along with additional information, such as where it was acquired, whether
92 /// it is exclusive or shared, etc.
93 ///
94 /// FIXME: this analysis does not currently support either re-entrant
95 /// locking or lock "upgrading" and "downgrading" between exclusive and
96 /// shared.
97 class FactEntry : public CapabilityExpr {
98 private:
99 LockKind LKind; ///< exclusive or shared
100 SourceLocation AcquireLoc; ///< where it was acquired.
101 bool Asserted; ///< true if the lock was asserted
102 bool Declared; ///< true if the lock was declared
103
104 public:
FactEntry(const CapabilityExpr & CE,LockKind LK,SourceLocation Loc,bool Asrt,bool Declrd=false)105 FactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
106 bool Asrt, bool Declrd = false)
107 : CapabilityExpr(CE), LKind(LK), AcquireLoc(Loc), Asserted(Asrt),
108 Declared(Declrd) {}
109
~FactEntry()110 virtual ~FactEntry() {}
111
kind() const112 LockKind kind() const { return LKind; }
loc() const113 SourceLocation loc() const { return AcquireLoc; }
asserted() const114 bool asserted() const { return Asserted; }
declared() const115 bool declared() const { return Declared; }
116
setDeclared(bool D)117 void setDeclared(bool D) { Declared = D; }
118
119 virtual void
120 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
121 SourceLocation JoinLoc, LockErrorKind LEK,
122 ThreadSafetyHandler &Handler) const = 0;
123 virtual void handleUnlock(FactSet &FSet, FactManager &FactMan,
124 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
125 bool FullyRemove, ThreadSafetyHandler &Handler,
126 StringRef DiagKind) const = 0;
127
128 // Return true if LKind >= LK, where exclusive > shared
isAtLeast(LockKind LK)129 bool isAtLeast(LockKind LK) {
130 return (LKind == LK_Exclusive) || (LK == LK_Shared);
131 }
132 };
133
134
135 typedef unsigned short FactID;
136
137 /// \brief FactManager manages the memory for all facts that are created during
138 /// the analysis of a single routine.
139 class FactManager {
140 private:
141 std::vector<std::unique_ptr<FactEntry>> Facts;
142
143 public:
newFact(std::unique_ptr<FactEntry> Entry)144 FactID newFact(std::unique_ptr<FactEntry> Entry) {
145 Facts.push_back(std::move(Entry));
146 return static_cast<unsigned short>(Facts.size() - 1);
147 }
148
operator [](FactID F) const149 const FactEntry &operator[](FactID F) const { return *Facts[F]; }
operator [](FactID F)150 FactEntry &operator[](FactID F) { return *Facts[F]; }
151 };
152
153
154 /// \brief A FactSet is the set of facts that are known to be true at a
155 /// particular program point. FactSets must be small, because they are
156 /// frequently copied, and are thus implemented as a set of indices into a
157 /// table maintained by a FactManager. A typical FactSet only holds 1 or 2
158 /// locks, so we can get away with doing a linear search for lookup. Note
159 /// that a hashtable or map is inappropriate in this case, because lookups
160 /// may involve partial pattern matches, rather than exact matches.
161 class FactSet {
162 private:
163 typedef SmallVector<FactID, 4> FactVec;
164
165 FactVec FactIDs;
166
167 public:
168 typedef FactVec::iterator iterator;
169 typedef FactVec::const_iterator const_iterator;
170
begin()171 iterator begin() { return FactIDs.begin(); }
begin() const172 const_iterator begin() const { return FactIDs.begin(); }
173
end()174 iterator end() { return FactIDs.end(); }
end() const175 const_iterator end() const { return FactIDs.end(); }
176
isEmpty() const177 bool isEmpty() const { return FactIDs.size() == 0; }
178
179 // Return true if the set contains only negative facts
isEmpty(FactManager & FactMan) const180 bool isEmpty(FactManager &FactMan) const {
181 for (FactID FID : *this) {
182 if (!FactMan[FID].negative())
183 return false;
184 }
185 return true;
186 }
187
addLockByID(FactID ID)188 void addLockByID(FactID ID) { FactIDs.push_back(ID); }
189
addLock(FactManager & FM,std::unique_ptr<FactEntry> Entry)190 FactID addLock(FactManager &FM, std::unique_ptr<FactEntry> Entry) {
191 FactID F = FM.newFact(std::move(Entry));
192 FactIDs.push_back(F);
193 return F;
194 }
195
removeLock(FactManager & FM,const CapabilityExpr & CapE)196 bool removeLock(FactManager& FM, const CapabilityExpr &CapE) {
197 unsigned n = FactIDs.size();
198 if (n == 0)
199 return false;
200
201 for (unsigned i = 0; i < n-1; ++i) {
202 if (FM[FactIDs[i]].matches(CapE)) {
203 FactIDs[i] = FactIDs[n-1];
204 FactIDs.pop_back();
205 return true;
206 }
207 }
208 if (FM[FactIDs[n-1]].matches(CapE)) {
209 FactIDs.pop_back();
210 return true;
211 }
212 return false;
213 }
214
findLockIter(FactManager & FM,const CapabilityExpr & CapE)215 iterator findLockIter(FactManager &FM, const CapabilityExpr &CapE) {
216 return std::find_if(begin(), end(), [&](FactID ID) {
217 return FM[ID].matches(CapE);
218 });
219 }
220
findLock(FactManager & FM,const CapabilityExpr & CapE) const221 FactEntry *findLock(FactManager &FM, const CapabilityExpr &CapE) const {
222 auto I = std::find_if(begin(), end(), [&](FactID ID) {
223 return FM[ID].matches(CapE);
224 });
225 return I != end() ? &FM[*I] : nullptr;
226 }
227
findLockUniv(FactManager & FM,const CapabilityExpr & CapE) const228 FactEntry *findLockUniv(FactManager &FM, const CapabilityExpr &CapE) const {
229 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
230 return FM[ID].matchesUniv(CapE);
231 });
232 return I != end() ? &FM[*I] : nullptr;
233 }
234
findPartialMatch(FactManager & FM,const CapabilityExpr & CapE) const235 FactEntry *findPartialMatch(FactManager &FM,
236 const CapabilityExpr &CapE) const {
237 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
238 return FM[ID].partiallyMatches(CapE);
239 });
240 return I != end() ? &FM[*I] : nullptr;
241 }
242
containsMutexDecl(FactManager & FM,const ValueDecl * Vd) const243 bool containsMutexDecl(FactManager &FM, const ValueDecl* Vd) const {
244 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
245 return FM[ID].valueDecl() == Vd;
246 });
247 return I != end();
248 }
249 };
250
251 class ThreadSafetyAnalyzer;
252 } // namespace
253
254 namespace clang {
255 namespace threadSafety {
256 class BeforeSet {
257 private:
258 typedef SmallVector<const ValueDecl*, 4> BeforeVect;
259
260 struct BeforeInfo {
BeforeInfoclang::threadSafety::BeforeSet::BeforeInfo261 BeforeInfo() : Visited(0) {}
BeforeInfoclang::threadSafety::BeforeSet::BeforeInfo262 BeforeInfo(BeforeInfo &&O) : Vect(std::move(O.Vect)), Visited(O.Visited) {}
263
264 BeforeVect Vect;
265 int Visited;
266 };
267
268 typedef llvm::DenseMap<const ValueDecl *, std::unique_ptr<BeforeInfo>>
269 BeforeMap;
270 typedef llvm::DenseMap<const ValueDecl*, bool> CycleMap;
271
272 public:
BeforeSet()273 BeforeSet() { }
274
275 BeforeInfo* insertAttrExprs(const ValueDecl* Vd,
276 ThreadSafetyAnalyzer& Analyzer);
277
278 BeforeInfo *getBeforeInfoForDecl(const ValueDecl *Vd,
279 ThreadSafetyAnalyzer &Analyzer);
280
281 void checkBeforeAfter(const ValueDecl* Vd,
282 const FactSet& FSet,
283 ThreadSafetyAnalyzer& Analyzer,
284 SourceLocation Loc, StringRef CapKind);
285
286 private:
287 BeforeMap BMap;
288 CycleMap CycMap;
289 };
290 } // end namespace threadSafety
291 } // end namespace clang
292
293 namespace {
294 typedef llvm::ImmutableMap<const NamedDecl*, unsigned> LocalVarContext;
295 class LocalVariableMap;
296
297 /// A side (entry or exit) of a CFG node.
298 enum CFGBlockSide { CBS_Entry, CBS_Exit };
299
300 /// CFGBlockInfo is a struct which contains all the information that is
301 /// maintained for each block in the CFG. See LocalVariableMap for more
302 /// information about the contexts.
303 struct CFGBlockInfo {
304 FactSet EntrySet; // Lockset held at entry to block
305 FactSet ExitSet; // Lockset held at exit from block
306 LocalVarContext EntryContext; // Context held at entry to block
307 LocalVarContext ExitContext; // Context held at exit from block
308 SourceLocation EntryLoc; // Location of first statement in block
309 SourceLocation ExitLoc; // Location of last statement in block.
310 unsigned EntryIndex; // Used to replay contexts later
311 bool Reachable; // Is this block reachable?
312
getSet__anon4f66b6dc0811::CFGBlockInfo313 const FactSet &getSet(CFGBlockSide Side) const {
314 return Side == CBS_Entry ? EntrySet : ExitSet;
315 }
getLocation__anon4f66b6dc0811::CFGBlockInfo316 SourceLocation getLocation(CFGBlockSide Side) const {
317 return Side == CBS_Entry ? EntryLoc : ExitLoc;
318 }
319
320 private:
CFGBlockInfo__anon4f66b6dc0811::CFGBlockInfo321 CFGBlockInfo(LocalVarContext EmptyCtx)
322 : EntryContext(EmptyCtx), ExitContext(EmptyCtx), Reachable(false)
323 { }
324
325 public:
326 static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
327 };
328
329
330
331 // A LocalVariableMap maintains a map from local variables to their currently
332 // valid definitions. It provides SSA-like functionality when traversing the
333 // CFG. Like SSA, each definition or assignment to a variable is assigned a
334 // unique name (an integer), which acts as the SSA name for that definition.
335 // The total set of names is shared among all CFG basic blocks.
336 // Unlike SSA, we do not rewrite expressions to replace local variables declrefs
337 // with their SSA-names. Instead, we compute a Context for each point in the
338 // code, which maps local variables to the appropriate SSA-name. This map
339 // changes with each assignment.
340 //
341 // The map is computed in a single pass over the CFG. Subsequent analyses can
342 // then query the map to find the appropriate Context for a statement, and use
343 // that Context to look up the definitions of variables.
344 class LocalVariableMap {
345 public:
346 typedef LocalVarContext Context;
347
348 /// A VarDefinition consists of an expression, representing the value of the
349 /// variable, along with the context in which that expression should be
350 /// interpreted. A reference VarDefinition does not itself contain this
351 /// information, but instead contains a pointer to a previous VarDefinition.
352 struct VarDefinition {
353 public:
354 friend class LocalVariableMap;
355
356 const NamedDecl *Dec; // The original declaration for this variable.
357 const Expr *Exp; // The expression for this variable, OR
358 unsigned Ref; // Reference to another VarDefinition
359 Context Ctx; // The map with which Exp should be interpreted.
360
isReference__anon4f66b6dc0811::LocalVariableMap::VarDefinition361 bool isReference() { return !Exp; }
362
363 private:
364 // Create ordinary variable definition
VarDefinition__anon4f66b6dc0811::LocalVariableMap::VarDefinition365 VarDefinition(const NamedDecl *D, const Expr *E, Context C)
366 : Dec(D), Exp(E), Ref(0), Ctx(C)
367 { }
368
369 // Create reference to previous definition
VarDefinition__anon4f66b6dc0811::LocalVariableMap::VarDefinition370 VarDefinition(const NamedDecl *D, unsigned R, Context C)
371 : Dec(D), Exp(nullptr), Ref(R), Ctx(C)
372 { }
373 };
374
375 private:
376 Context::Factory ContextFactory;
377 std::vector<VarDefinition> VarDefinitions;
378 std::vector<unsigned> CtxIndices;
379 std::vector<std::pair<Stmt*, Context> > SavedContexts;
380
381 public:
LocalVariableMap()382 LocalVariableMap() {
383 // index 0 is a placeholder for undefined variables (aka phi-nodes).
384 VarDefinitions.push_back(VarDefinition(nullptr, 0u, getEmptyContext()));
385 }
386
387 /// Look up a definition, within the given context.
lookup(const NamedDecl * D,Context Ctx)388 const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
389 const unsigned *i = Ctx.lookup(D);
390 if (!i)
391 return nullptr;
392 assert(*i < VarDefinitions.size());
393 return &VarDefinitions[*i];
394 }
395
396 /// Look up the definition for D within the given context. Returns
397 /// NULL if the expression is not statically known. If successful, also
398 /// modifies Ctx to hold the context of the return Expr.
lookupExpr(const NamedDecl * D,Context & Ctx)399 const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
400 const unsigned *P = Ctx.lookup(D);
401 if (!P)
402 return nullptr;
403
404 unsigned i = *P;
405 while (i > 0) {
406 if (VarDefinitions[i].Exp) {
407 Ctx = VarDefinitions[i].Ctx;
408 return VarDefinitions[i].Exp;
409 }
410 i = VarDefinitions[i].Ref;
411 }
412 return nullptr;
413 }
414
getEmptyContext()415 Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
416
417 /// Return the next context after processing S. This function is used by
418 /// clients of the class to get the appropriate context when traversing the
419 /// CFG. It must be called for every assignment or DeclStmt.
getNextContext(unsigned & CtxIndex,Stmt * S,Context C)420 Context getNextContext(unsigned &CtxIndex, Stmt *S, Context C) {
421 if (SavedContexts[CtxIndex+1].first == S) {
422 CtxIndex++;
423 Context Result = SavedContexts[CtxIndex].second;
424 return Result;
425 }
426 return C;
427 }
428
dumpVarDefinitionName(unsigned i)429 void dumpVarDefinitionName(unsigned i) {
430 if (i == 0) {
431 llvm::errs() << "Undefined";
432 return;
433 }
434 const NamedDecl *Dec = VarDefinitions[i].Dec;
435 if (!Dec) {
436 llvm::errs() << "<<NULL>>";
437 return;
438 }
439 Dec->printName(llvm::errs());
440 llvm::errs() << "." << i << " " << ((const void*) Dec);
441 }
442
443 /// Dumps an ASCII representation of the variable map to llvm::errs()
dump()444 void dump() {
445 for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
446 const Expr *Exp = VarDefinitions[i].Exp;
447 unsigned Ref = VarDefinitions[i].Ref;
448
449 dumpVarDefinitionName(i);
450 llvm::errs() << " = ";
451 if (Exp) Exp->dump();
452 else {
453 dumpVarDefinitionName(Ref);
454 llvm::errs() << "\n";
455 }
456 }
457 }
458
459 /// Dumps an ASCII representation of a Context to llvm::errs()
dumpContext(Context C)460 void dumpContext(Context C) {
461 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
462 const NamedDecl *D = I.getKey();
463 D->printName(llvm::errs());
464 const unsigned *i = C.lookup(D);
465 llvm::errs() << " -> ";
466 dumpVarDefinitionName(*i);
467 llvm::errs() << "\n";
468 }
469 }
470
471 /// Builds the variable map.
472 void traverseCFG(CFG *CFGraph, const PostOrderCFGView *SortedGraph,
473 std::vector<CFGBlockInfo> &BlockInfo);
474
475 protected:
476 // Get the current context index
getContextIndex()477 unsigned getContextIndex() { return SavedContexts.size()-1; }
478
479 // Save the current context for later replay
saveContext(Stmt * S,Context C)480 void saveContext(Stmt *S, Context C) {
481 SavedContexts.push_back(std::make_pair(S,C));
482 }
483
484 // Adds a new definition to the given context, and returns a new context.
485 // This method should be called when declaring a new variable.
addDefinition(const NamedDecl * D,const Expr * Exp,Context Ctx)486 Context addDefinition(const NamedDecl *D, const Expr *Exp, Context Ctx) {
487 assert(!Ctx.contains(D));
488 unsigned newID = VarDefinitions.size();
489 Context NewCtx = ContextFactory.add(Ctx, D, newID);
490 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
491 return NewCtx;
492 }
493
494 // Add a new reference to an existing definition.
addReference(const NamedDecl * D,unsigned i,Context Ctx)495 Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
496 unsigned newID = VarDefinitions.size();
497 Context NewCtx = ContextFactory.add(Ctx, D, newID);
498 VarDefinitions.push_back(VarDefinition(D, i, Ctx));
499 return NewCtx;
500 }
501
502 // Updates a definition only if that definition is already in the map.
503 // This method should be called when assigning to an existing variable.
updateDefinition(const NamedDecl * D,Expr * Exp,Context Ctx)504 Context updateDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
505 if (Ctx.contains(D)) {
506 unsigned newID = VarDefinitions.size();
507 Context NewCtx = ContextFactory.remove(Ctx, D);
508 NewCtx = ContextFactory.add(NewCtx, D, newID);
509 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
510 return NewCtx;
511 }
512 return Ctx;
513 }
514
515 // Removes a definition from the context, but keeps the variable name
516 // as a valid variable. The index 0 is a placeholder for cleared definitions.
clearDefinition(const NamedDecl * D,Context Ctx)517 Context clearDefinition(const NamedDecl *D, Context Ctx) {
518 Context NewCtx = Ctx;
519 if (NewCtx.contains(D)) {
520 NewCtx = ContextFactory.remove(NewCtx, D);
521 NewCtx = ContextFactory.add(NewCtx, D, 0);
522 }
523 return NewCtx;
524 }
525
526 // Remove a definition entirely frmo the context.
removeDefinition(const NamedDecl * D,Context Ctx)527 Context removeDefinition(const NamedDecl *D, Context Ctx) {
528 Context NewCtx = Ctx;
529 if (NewCtx.contains(D)) {
530 NewCtx = ContextFactory.remove(NewCtx, D);
531 }
532 return NewCtx;
533 }
534
535 Context intersectContexts(Context C1, Context C2);
536 Context createReferenceContext(Context C);
537 void intersectBackEdge(Context C1, Context C2);
538
539 friend class VarMapBuilder;
540 };
541
542
543 // This has to be defined after LocalVariableMap.
getEmptyBlockInfo(LocalVariableMap & M)544 CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
545 return CFGBlockInfo(M.getEmptyContext());
546 }
547
548
549 /// Visitor which builds a LocalVariableMap
550 class VarMapBuilder : public StmtVisitor<VarMapBuilder> {
551 public:
552 LocalVariableMap* VMap;
553 LocalVariableMap::Context Ctx;
554
VarMapBuilder(LocalVariableMap * VM,LocalVariableMap::Context C)555 VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
556 : VMap(VM), Ctx(C) {}
557
558 void VisitDeclStmt(DeclStmt *S);
559 void VisitBinaryOperator(BinaryOperator *BO);
560 };
561
562
563 // Add new local variables to the variable map
VisitDeclStmt(DeclStmt * S)564 void VarMapBuilder::VisitDeclStmt(DeclStmt *S) {
565 bool modifiedCtx = false;
566 DeclGroupRef DGrp = S->getDeclGroup();
567 for (const auto *D : DGrp) {
568 if (const auto *VD = dyn_cast_or_null<VarDecl>(D)) {
569 const Expr *E = VD->getInit();
570
571 // Add local variables with trivial type to the variable map
572 QualType T = VD->getType();
573 if (T.isTrivialType(VD->getASTContext())) {
574 Ctx = VMap->addDefinition(VD, E, Ctx);
575 modifiedCtx = true;
576 }
577 }
578 }
579 if (modifiedCtx)
580 VMap->saveContext(S, Ctx);
581 }
582
583 // Update local variable definitions in variable map
VisitBinaryOperator(BinaryOperator * BO)584 void VarMapBuilder::VisitBinaryOperator(BinaryOperator *BO) {
585 if (!BO->isAssignmentOp())
586 return;
587
588 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
589
590 // Update the variable map and current context.
591 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
592 ValueDecl *VDec = DRE->getDecl();
593 if (Ctx.lookup(VDec)) {
594 if (BO->getOpcode() == BO_Assign)
595 Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
596 else
597 // FIXME -- handle compound assignment operators
598 Ctx = VMap->clearDefinition(VDec, Ctx);
599 VMap->saveContext(BO, Ctx);
600 }
601 }
602 }
603
604
605 // Computes the intersection of two contexts. The intersection is the
606 // set of variables which have the same definition in both contexts;
607 // variables with different definitions are discarded.
608 LocalVariableMap::Context
intersectContexts(Context C1,Context C2)609 LocalVariableMap::intersectContexts(Context C1, Context C2) {
610 Context Result = C1;
611 for (const auto &P : C1) {
612 const NamedDecl *Dec = P.first;
613 const unsigned *i2 = C2.lookup(Dec);
614 if (!i2) // variable doesn't exist on second path
615 Result = removeDefinition(Dec, Result);
616 else if (*i2 != P.second) // variable exists, but has different definition
617 Result = clearDefinition(Dec, Result);
618 }
619 return Result;
620 }
621
622 // For every variable in C, create a new variable that refers to the
623 // definition in C. Return a new context that contains these new variables.
624 // (We use this for a naive implementation of SSA on loop back-edges.)
createReferenceContext(Context C)625 LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
626 Context Result = getEmptyContext();
627 for (const auto &P : C)
628 Result = addReference(P.first, P.second, Result);
629 return Result;
630 }
631
632 // This routine also takes the intersection of C1 and C2, but it does so by
633 // altering the VarDefinitions. C1 must be the result of an earlier call to
634 // createReferenceContext.
intersectBackEdge(Context C1,Context C2)635 void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
636 for (const auto &P : C1) {
637 unsigned i1 = P.second;
638 VarDefinition *VDef = &VarDefinitions[i1];
639 assert(VDef->isReference());
640
641 const unsigned *i2 = C2.lookup(P.first);
642 if (!i2 || (*i2 != i1))
643 VDef->Ref = 0; // Mark this variable as undefined
644 }
645 }
646
647
648 // Traverse the CFG in topological order, so all predecessors of a block
649 // (excluding back-edges) are visited before the block itself. At
650 // each point in the code, we calculate a Context, which holds the set of
651 // variable definitions which are visible at that point in execution.
652 // Visible variables are mapped to their definitions using an array that
653 // contains all definitions.
654 //
655 // At join points in the CFG, the set is computed as the intersection of
656 // the incoming sets along each edge, E.g.
657 //
658 // { Context | VarDefinitions }
659 // int x = 0; { x -> x1 | x1 = 0 }
660 // int y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
661 // if (b) x = 1; { x -> x2, y -> y1 | x2 = 1, y1 = 0, ... }
662 // else x = 2; { x -> x3, y -> y1 | x3 = 2, x2 = 1, ... }
663 // ... { y -> y1 (x is unknown) | x3 = 2, x2 = 1, ... }
664 //
665 // This is essentially a simpler and more naive version of the standard SSA
666 // algorithm. Those definitions that remain in the intersection are from blocks
667 // that strictly dominate the current block. We do not bother to insert proper
668 // phi nodes, because they are not used in our analysis; instead, wherever
669 // a phi node would be required, we simply remove that definition from the
670 // context (E.g. x above).
671 //
672 // The initial traversal does not capture back-edges, so those need to be
673 // handled on a separate pass. Whenever the first pass encounters an
674 // incoming back edge, it duplicates the context, creating new definitions
675 // that refer back to the originals. (These correspond to places where SSA
676 // might have to insert a phi node.) On the second pass, these definitions are
677 // set to NULL if the variable has changed on the back-edge (i.e. a phi
678 // node was actually required.) E.g.
679 //
680 // { Context | VarDefinitions }
681 // int x = 0, y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
682 // while (b) { x -> x2, y -> y1 | [1st:] x2=x1; [2nd:] x2=NULL; }
683 // x = x+1; { x -> x3, y -> y1 | x3 = x2 + 1, ... }
684 // ... { y -> y1 | x3 = 2, x2 = 1, ... }
685 //
traverseCFG(CFG * CFGraph,const PostOrderCFGView * SortedGraph,std::vector<CFGBlockInfo> & BlockInfo)686 void LocalVariableMap::traverseCFG(CFG *CFGraph,
687 const PostOrderCFGView *SortedGraph,
688 std::vector<CFGBlockInfo> &BlockInfo) {
689 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
690
691 CtxIndices.resize(CFGraph->getNumBlockIDs());
692
693 for (const auto *CurrBlock : *SortedGraph) {
694 int CurrBlockID = CurrBlock->getBlockID();
695 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
696
697 VisitedBlocks.insert(CurrBlock);
698
699 // Calculate the entry context for the current block
700 bool HasBackEdges = false;
701 bool CtxInit = true;
702 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
703 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
704 // if *PI -> CurrBlock is a back edge, so skip it
705 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI)) {
706 HasBackEdges = true;
707 continue;
708 }
709
710 int PrevBlockID = (*PI)->getBlockID();
711 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
712
713 if (CtxInit) {
714 CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
715 CtxInit = false;
716 }
717 else {
718 CurrBlockInfo->EntryContext =
719 intersectContexts(CurrBlockInfo->EntryContext,
720 PrevBlockInfo->ExitContext);
721 }
722 }
723
724 // Duplicate the context if we have back-edges, so we can call
725 // intersectBackEdges later.
726 if (HasBackEdges)
727 CurrBlockInfo->EntryContext =
728 createReferenceContext(CurrBlockInfo->EntryContext);
729
730 // Create a starting context index for the current block
731 saveContext(nullptr, CurrBlockInfo->EntryContext);
732 CurrBlockInfo->EntryIndex = getContextIndex();
733
734 // Visit all the statements in the basic block.
735 VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
736 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
737 BE = CurrBlock->end(); BI != BE; ++BI) {
738 switch (BI->getKind()) {
739 case CFGElement::Statement: {
740 CFGStmt CS = BI->castAs<CFGStmt>();
741 VMapBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
742 break;
743 }
744 default:
745 break;
746 }
747 }
748 CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
749
750 // Mark variables on back edges as "unknown" if they've been changed.
751 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
752 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
753 // if CurrBlock -> *SI is *not* a back edge
754 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
755 continue;
756
757 CFGBlock *FirstLoopBlock = *SI;
758 Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
759 Context LoopEnd = CurrBlockInfo->ExitContext;
760 intersectBackEdge(LoopBegin, LoopEnd);
761 }
762 }
763
764 // Put an extra entry at the end of the indexed context array
765 unsigned exitID = CFGraph->getExit().getBlockID();
766 saveContext(nullptr, BlockInfo[exitID].ExitContext);
767 }
768
769 /// Find the appropriate source locations to use when producing diagnostics for
770 /// each block in the CFG.
findBlockLocations(CFG * CFGraph,const PostOrderCFGView * SortedGraph,std::vector<CFGBlockInfo> & BlockInfo)771 static void findBlockLocations(CFG *CFGraph,
772 const PostOrderCFGView *SortedGraph,
773 std::vector<CFGBlockInfo> &BlockInfo) {
774 for (const auto *CurrBlock : *SortedGraph) {
775 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
776
777 // Find the source location of the last statement in the block, if the
778 // block is not empty.
779 if (const Stmt *S = CurrBlock->getTerminator()) {
780 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getLocStart();
781 } else {
782 for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
783 BE = CurrBlock->rend(); BI != BE; ++BI) {
784 // FIXME: Handle other CFGElement kinds.
785 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
786 CurrBlockInfo->ExitLoc = CS->getStmt()->getLocStart();
787 break;
788 }
789 }
790 }
791
792 if (CurrBlockInfo->ExitLoc.isValid()) {
793 // This block contains at least one statement. Find the source location
794 // of the first statement in the block.
795 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
796 BE = CurrBlock->end(); BI != BE; ++BI) {
797 // FIXME: Handle other CFGElement kinds.
798 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
799 CurrBlockInfo->EntryLoc = CS->getStmt()->getLocStart();
800 break;
801 }
802 }
803 } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
804 CurrBlock != &CFGraph->getExit()) {
805 // The block is empty, and has a single predecessor. Use its exit
806 // location.
807 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
808 BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
809 }
810 }
811 }
812
813 class LockableFactEntry : public FactEntry {
814 private:
815 bool Managed; ///< managed by ScopedLockable object
816
817 public:
LockableFactEntry(const CapabilityExpr & CE,LockKind LK,SourceLocation Loc,bool Mng=false,bool Asrt=false)818 LockableFactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
819 bool Mng = false, bool Asrt = false)
820 : FactEntry(CE, LK, Loc, Asrt), Managed(Mng) {}
821
822 void
handleRemovalFromIntersection(const FactSet & FSet,FactManager & FactMan,SourceLocation JoinLoc,LockErrorKind LEK,ThreadSafetyHandler & Handler) const823 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
824 SourceLocation JoinLoc, LockErrorKind LEK,
825 ThreadSafetyHandler &Handler) const override {
826 if (!Managed && !asserted() && !negative() && !isUniversal()) {
827 Handler.handleMutexHeldEndOfScope("mutex", toString(), loc(), JoinLoc,
828 LEK);
829 }
830 }
831
handleUnlock(FactSet & FSet,FactManager & FactMan,const CapabilityExpr & Cp,SourceLocation UnlockLoc,bool FullyRemove,ThreadSafetyHandler & Handler,StringRef DiagKind) const832 void handleUnlock(FactSet &FSet, FactManager &FactMan,
833 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
834 bool FullyRemove, ThreadSafetyHandler &Handler,
835 StringRef DiagKind) const override {
836 FSet.removeLock(FactMan, Cp);
837 if (!Cp.negative()) {
838 FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
839 !Cp, LK_Exclusive, UnlockLoc));
840 }
841 }
842 };
843
844 class ScopedLockableFactEntry : public FactEntry {
845 private:
846 SmallVector<const til::SExpr *, 4> UnderlyingMutexes;
847
848 public:
ScopedLockableFactEntry(const CapabilityExpr & CE,SourceLocation Loc,const CapExprSet & Excl,const CapExprSet & Shrd)849 ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc,
850 const CapExprSet &Excl, const CapExprSet &Shrd)
851 : FactEntry(CE, LK_Exclusive, Loc, false) {
852 for (const auto &M : Excl)
853 UnderlyingMutexes.push_back(M.sexpr());
854 for (const auto &M : Shrd)
855 UnderlyingMutexes.push_back(M.sexpr());
856 }
857
858 void
handleRemovalFromIntersection(const FactSet & FSet,FactManager & FactMan,SourceLocation JoinLoc,LockErrorKind LEK,ThreadSafetyHandler & Handler) const859 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
860 SourceLocation JoinLoc, LockErrorKind LEK,
861 ThreadSafetyHandler &Handler) const override {
862 for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
863 if (FSet.findLock(FactMan, CapabilityExpr(UnderlyingMutex, false))) {
864 // If this scoped lock manages another mutex, and if the underlying
865 // mutex is still held, then warn about the underlying mutex.
866 Handler.handleMutexHeldEndOfScope(
867 "mutex", sx::toString(UnderlyingMutex), loc(), JoinLoc, LEK);
868 }
869 }
870 }
871
handleUnlock(FactSet & FSet,FactManager & FactMan,const CapabilityExpr & Cp,SourceLocation UnlockLoc,bool FullyRemove,ThreadSafetyHandler & Handler,StringRef DiagKind) const872 void handleUnlock(FactSet &FSet, FactManager &FactMan,
873 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
874 bool FullyRemove, ThreadSafetyHandler &Handler,
875 StringRef DiagKind) const override {
876 assert(!Cp.negative() && "Managing object cannot be negative.");
877 for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
878 CapabilityExpr UnderCp(UnderlyingMutex, false);
879 auto UnderEntry = llvm::make_unique<LockableFactEntry>(
880 !UnderCp, LK_Exclusive, UnlockLoc);
881
882 if (FullyRemove) {
883 // We're destroying the managing object.
884 // Remove the underlying mutex if it exists; but don't warn.
885 if (FSet.findLock(FactMan, UnderCp)) {
886 FSet.removeLock(FactMan, UnderCp);
887 FSet.addLock(FactMan, std::move(UnderEntry));
888 }
889 } else {
890 // We're releasing the underlying mutex, but not destroying the
891 // managing object. Warn on dual release.
892 if (!FSet.findLock(FactMan, UnderCp)) {
893 Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
894 UnlockLoc);
895 }
896 FSet.removeLock(FactMan, UnderCp);
897 FSet.addLock(FactMan, std::move(UnderEntry));
898 }
899 }
900 if (FullyRemove)
901 FSet.removeLock(FactMan, Cp);
902 }
903 };
904
905 /// \brief Class which implements the core thread safety analysis routines.
906 class ThreadSafetyAnalyzer {
907 friend class BuildLockset;
908 friend class threadSafety::BeforeSet;
909
910 llvm::BumpPtrAllocator Bpa;
911 threadSafety::til::MemRegionRef Arena;
912 threadSafety::SExprBuilder SxBuilder;
913
914 ThreadSafetyHandler &Handler;
915 const CXXMethodDecl *CurrentMethod;
916 LocalVariableMap LocalVarMap;
917 FactManager FactMan;
918 std::vector<CFGBlockInfo> BlockInfo;
919
920 BeforeSet* GlobalBeforeSet;
921
922 public:
ThreadSafetyAnalyzer(ThreadSafetyHandler & H,BeforeSet * Bset)923 ThreadSafetyAnalyzer(ThreadSafetyHandler &H, BeforeSet* Bset)
924 : Arena(&Bpa), SxBuilder(Arena), Handler(H), GlobalBeforeSet(Bset) {}
925
926 bool inCurrentScope(const CapabilityExpr &CapE);
927
928 void addLock(FactSet &FSet, std::unique_ptr<FactEntry> Entry,
929 StringRef DiagKind, bool ReqAttr = false);
930 void removeLock(FactSet &FSet, const CapabilityExpr &CapE,
931 SourceLocation UnlockLoc, bool FullyRemove, LockKind Kind,
932 StringRef DiagKind);
933
934 template <typename AttrType>
935 void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
936 const NamedDecl *D, VarDecl *SelfDecl = nullptr);
937
938 template <class AttrType>
939 void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
940 const NamedDecl *D,
941 const CFGBlock *PredBlock, const CFGBlock *CurrBlock,
942 Expr *BrE, bool Neg);
943
944 const CallExpr* getTrylockCallExpr(const Stmt *Cond, LocalVarContext C,
945 bool &Negate);
946
947 void getEdgeLockset(FactSet &Result, const FactSet &ExitSet,
948 const CFGBlock* PredBlock,
949 const CFGBlock *CurrBlock);
950
951 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
952 SourceLocation JoinLoc,
953 LockErrorKind LEK1, LockErrorKind LEK2,
954 bool Modify=true);
955
intersectAndWarn(FactSet & FSet1,const FactSet & FSet2,SourceLocation JoinLoc,LockErrorKind LEK1,bool Modify=true)956 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
957 SourceLocation JoinLoc, LockErrorKind LEK1,
958 bool Modify=true) {
959 intersectAndWarn(FSet1, FSet2, JoinLoc, LEK1, LEK1, Modify);
960 }
961
962 void runAnalysis(AnalysisDeclContext &AC);
963 };
964 } // namespace
965
966 /// Process acquired_before and acquired_after attributes on Vd.
insertAttrExprs(const ValueDecl * Vd,ThreadSafetyAnalyzer & Analyzer)967 BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
968 ThreadSafetyAnalyzer& Analyzer) {
969 // Create a new entry for Vd.
970 BeforeInfo *Info = nullptr;
971 {
972 // Keep InfoPtr in its own scope in case BMap is modified later and the
973 // reference becomes invalid.
974 std::unique_ptr<BeforeInfo> &InfoPtr = BMap[Vd];
975 if (!InfoPtr)
976 InfoPtr.reset(new BeforeInfo());
977 Info = InfoPtr.get();
978 }
979
980 for (Attr* At : Vd->attrs()) {
981 switch (At->getKind()) {
982 case attr::AcquiredBefore: {
983 auto *A = cast<AcquiredBeforeAttr>(At);
984
985 // Read exprs from the attribute, and add them to BeforeVect.
986 for (const auto *Arg : A->args()) {
987 CapabilityExpr Cp =
988 Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
989 if (const ValueDecl *Cpvd = Cp.valueDecl()) {
990 Info->Vect.push_back(Cpvd);
991 auto It = BMap.find(Cpvd);
992 if (It == BMap.end())
993 insertAttrExprs(Cpvd, Analyzer);
994 }
995 }
996 break;
997 }
998 case attr::AcquiredAfter: {
999 auto *A = cast<AcquiredAfterAttr>(At);
1000
1001 // Read exprs from the attribute, and add them to BeforeVect.
1002 for (const auto *Arg : A->args()) {
1003 CapabilityExpr Cp =
1004 Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
1005 if (const ValueDecl *ArgVd = Cp.valueDecl()) {
1006 // Get entry for mutex listed in attribute
1007 BeforeInfo *ArgInfo = getBeforeInfoForDecl(ArgVd, Analyzer);
1008 ArgInfo->Vect.push_back(Vd);
1009 }
1010 }
1011 break;
1012 }
1013 default:
1014 break;
1015 }
1016 }
1017
1018 return Info;
1019 }
1020
1021 BeforeSet::BeforeInfo *
getBeforeInfoForDecl(const ValueDecl * Vd,ThreadSafetyAnalyzer & Analyzer)1022 BeforeSet::getBeforeInfoForDecl(const ValueDecl *Vd,
1023 ThreadSafetyAnalyzer &Analyzer) {
1024 auto It = BMap.find(Vd);
1025 BeforeInfo *Info = nullptr;
1026 if (It == BMap.end())
1027 Info = insertAttrExprs(Vd, Analyzer);
1028 else
1029 Info = It->second.get();
1030 assert(Info && "BMap contained nullptr?");
1031 return Info;
1032 }
1033
1034 /// Return true if any mutexes in FSet are in the acquired_before set of Vd.
checkBeforeAfter(const ValueDecl * StartVd,const FactSet & FSet,ThreadSafetyAnalyzer & Analyzer,SourceLocation Loc,StringRef CapKind)1035 void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
1036 const FactSet& FSet,
1037 ThreadSafetyAnalyzer& Analyzer,
1038 SourceLocation Loc, StringRef CapKind) {
1039 SmallVector<BeforeInfo*, 8> InfoVect;
1040
1041 // Do a depth-first traversal of Vd.
1042 // Return true if there are cycles.
1043 std::function<bool (const ValueDecl*)> traverse = [&](const ValueDecl* Vd) {
1044 if (!Vd)
1045 return false;
1046
1047 BeforeSet::BeforeInfo *Info = getBeforeInfoForDecl(Vd, Analyzer);
1048
1049 if (Info->Visited == 1)
1050 return true;
1051
1052 if (Info->Visited == 2)
1053 return false;
1054
1055 if (Info->Vect.empty())
1056 return false;
1057
1058 InfoVect.push_back(Info);
1059 Info->Visited = 1;
1060 for (auto *Vdb : Info->Vect) {
1061 // Exclude mutexes in our immediate before set.
1062 if (FSet.containsMutexDecl(Analyzer.FactMan, Vdb)) {
1063 StringRef L1 = StartVd->getName();
1064 StringRef L2 = Vdb->getName();
1065 Analyzer.Handler.handleLockAcquiredBefore(CapKind, L1, L2, Loc);
1066 }
1067 // Transitively search other before sets, and warn on cycles.
1068 if (traverse(Vdb)) {
1069 if (CycMap.find(Vd) == CycMap.end()) {
1070 CycMap.insert(std::make_pair(Vd, true));
1071 StringRef L1 = Vd->getName();
1072 Analyzer.Handler.handleBeforeAfterCycle(L1, Vd->getLocation());
1073 }
1074 }
1075 }
1076 Info->Visited = 2;
1077 return false;
1078 };
1079
1080 traverse(StartVd);
1081
1082 for (auto* Info : InfoVect)
1083 Info->Visited = 0;
1084 }
1085
1086
1087
1088 /// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs.
getValueDecl(const Expr * Exp)1089 static const ValueDecl *getValueDecl(const Expr *Exp) {
1090 if (const auto *CE = dyn_cast<ImplicitCastExpr>(Exp))
1091 return getValueDecl(CE->getSubExpr());
1092
1093 if (const auto *DR = dyn_cast<DeclRefExpr>(Exp))
1094 return DR->getDecl();
1095
1096 if (const auto *ME = dyn_cast<MemberExpr>(Exp))
1097 return ME->getMemberDecl();
1098
1099 return nullptr;
1100 }
1101
1102 namespace {
1103 template <typename Ty>
1104 class has_arg_iterator_range {
1105 typedef char yes[1];
1106 typedef char no[2];
1107
1108 template <typename Inner>
1109 static yes& test(Inner *I, decltype(I->args()) * = nullptr);
1110
1111 template <typename>
1112 static no& test(...);
1113
1114 public:
1115 static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
1116 };
1117 } // namespace
1118
ClassifyDiagnostic(const CapabilityAttr * A)1119 static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
1120 return A->getName();
1121 }
1122
ClassifyDiagnostic(QualType VDT)1123 static StringRef ClassifyDiagnostic(QualType VDT) {
1124 // We need to look at the declaration of the type of the value to determine
1125 // which it is. The type should either be a record or a typedef, or a pointer
1126 // or reference thereof.
1127 if (const auto *RT = VDT->getAs<RecordType>()) {
1128 if (const auto *RD = RT->getDecl())
1129 if (const auto *CA = RD->getAttr<CapabilityAttr>())
1130 return ClassifyDiagnostic(CA);
1131 } else if (const auto *TT = VDT->getAs<TypedefType>()) {
1132 if (const auto *TD = TT->getDecl())
1133 if (const auto *CA = TD->getAttr<CapabilityAttr>())
1134 return ClassifyDiagnostic(CA);
1135 } else if (VDT->isPointerType() || VDT->isReferenceType())
1136 return ClassifyDiagnostic(VDT->getPointeeType());
1137
1138 return "mutex";
1139 }
1140
ClassifyDiagnostic(const ValueDecl * VD)1141 static StringRef ClassifyDiagnostic(const ValueDecl *VD) {
1142 assert(VD && "No ValueDecl passed");
1143
1144 // The ValueDecl is the declaration of a mutex or role (hopefully).
1145 return ClassifyDiagnostic(VD->getType());
1146 }
1147
1148 template <typename AttrTy>
1149 static typename std::enable_if<!has_arg_iterator_range<AttrTy>::value,
1150 StringRef>::type
ClassifyDiagnostic(const AttrTy * A)1151 ClassifyDiagnostic(const AttrTy *A) {
1152 if (const ValueDecl *VD = getValueDecl(A->getArg()))
1153 return ClassifyDiagnostic(VD);
1154 return "mutex";
1155 }
1156
1157 template <typename AttrTy>
1158 static typename std::enable_if<has_arg_iterator_range<AttrTy>::value,
1159 StringRef>::type
ClassifyDiagnostic(const AttrTy * A)1160 ClassifyDiagnostic(const AttrTy *A) {
1161 for (const auto *Arg : A->args()) {
1162 if (const ValueDecl *VD = getValueDecl(Arg))
1163 return ClassifyDiagnostic(VD);
1164 }
1165 return "mutex";
1166 }
1167
1168
inCurrentScope(const CapabilityExpr & CapE)1169 inline bool ThreadSafetyAnalyzer::inCurrentScope(const CapabilityExpr &CapE) {
1170 if (!CurrentMethod)
1171 return false;
1172 if (auto *P = dyn_cast_or_null<til::Project>(CapE.sexpr())) {
1173 auto *VD = P->clangDecl();
1174 if (VD)
1175 return VD->getDeclContext() == CurrentMethod->getDeclContext();
1176 }
1177 return false;
1178 }
1179
1180
1181 /// \brief Add a new lock to the lockset, warning if the lock is already there.
1182 /// \param ReqAttr -- true if this is part of an initial Requires attribute.
addLock(FactSet & FSet,std::unique_ptr<FactEntry> Entry,StringRef DiagKind,bool ReqAttr)1183 void ThreadSafetyAnalyzer::addLock(FactSet &FSet,
1184 std::unique_ptr<FactEntry> Entry,
1185 StringRef DiagKind, bool ReqAttr) {
1186 if (Entry->shouldIgnore())
1187 return;
1188
1189 if (!ReqAttr && !Entry->negative()) {
1190 // look for the negative capability, and remove it from the fact set.
1191 CapabilityExpr NegC = !*Entry;
1192 FactEntry *Nen = FSet.findLock(FactMan, NegC);
1193 if (Nen) {
1194 FSet.removeLock(FactMan, NegC);
1195 }
1196 else {
1197 if (inCurrentScope(*Entry) && !Entry->asserted())
1198 Handler.handleNegativeNotHeld(DiagKind, Entry->toString(),
1199 NegC.toString(), Entry->loc());
1200 }
1201 }
1202
1203 // Check before/after constraints
1204 if (Handler.issueBetaWarnings() &&
1205 !Entry->asserted() && !Entry->declared()) {
1206 GlobalBeforeSet->checkBeforeAfter(Entry->valueDecl(), FSet, *this,
1207 Entry->loc(), DiagKind);
1208 }
1209
1210 // FIXME: Don't always warn when we have support for reentrant locks.
1211 if (FSet.findLock(FactMan, *Entry)) {
1212 if (!Entry->asserted())
1213 Handler.handleDoubleLock(DiagKind, Entry->toString(), Entry->loc());
1214 } else {
1215 FSet.addLock(FactMan, std::move(Entry));
1216 }
1217 }
1218
1219
1220 /// \brief Remove a lock from the lockset, warning if the lock is not there.
1221 /// \param UnlockLoc The source location of the unlock (only used in error msg)
removeLock(FactSet & FSet,const CapabilityExpr & Cp,SourceLocation UnlockLoc,bool FullyRemove,LockKind ReceivedKind,StringRef DiagKind)1222 void ThreadSafetyAnalyzer::removeLock(FactSet &FSet, const CapabilityExpr &Cp,
1223 SourceLocation UnlockLoc,
1224 bool FullyRemove, LockKind ReceivedKind,
1225 StringRef DiagKind) {
1226 if (Cp.shouldIgnore())
1227 return;
1228
1229 const FactEntry *LDat = FSet.findLock(FactMan, Cp);
1230 if (!LDat) {
1231 Handler.handleUnmatchedUnlock(DiagKind, Cp.toString(), UnlockLoc);
1232 return;
1233 }
1234
1235 // Generic lock removal doesn't care about lock kind mismatches, but
1236 // otherwise diagnose when the lock kinds are mismatched.
1237 if (ReceivedKind != LK_Generic && LDat->kind() != ReceivedKind) {
1238 Handler.handleIncorrectUnlockKind(DiagKind, Cp.toString(),
1239 LDat->kind(), ReceivedKind, UnlockLoc);
1240 }
1241
1242 LDat->handleUnlock(FSet, FactMan, Cp, UnlockLoc, FullyRemove, Handler,
1243 DiagKind);
1244 }
1245
1246
1247 /// \brief Extract the list of mutexIDs from the attribute on an expression,
1248 /// and push them onto Mtxs, discarding any duplicates.
1249 template <typename AttrType>
getMutexIDs(CapExprSet & Mtxs,AttrType * Attr,Expr * Exp,const NamedDecl * D,VarDecl * SelfDecl)1250 void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1251 Expr *Exp, const NamedDecl *D,
1252 VarDecl *SelfDecl) {
1253 if (Attr->args_size() == 0) {
1254 // The mutex held is the "this" object.
1255 CapabilityExpr Cp = SxBuilder.translateAttrExpr(nullptr, D, Exp, SelfDecl);
1256 if (Cp.isInvalid()) {
1257 warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1258 return;
1259 }
1260 //else
1261 if (!Cp.shouldIgnore())
1262 Mtxs.push_back_nodup(Cp);
1263 return;
1264 }
1265
1266 for (const auto *Arg : Attr->args()) {
1267 CapabilityExpr Cp = SxBuilder.translateAttrExpr(Arg, D, Exp, SelfDecl);
1268 if (Cp.isInvalid()) {
1269 warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1270 continue;
1271 }
1272 //else
1273 if (!Cp.shouldIgnore())
1274 Mtxs.push_back_nodup(Cp);
1275 }
1276 }
1277
1278
1279 /// \brief Extract the list of mutexIDs from a trylock attribute. If the
1280 /// trylock applies to the given edge, then push them onto Mtxs, discarding
1281 /// any duplicates.
1282 template <class AttrType>
getMutexIDs(CapExprSet & Mtxs,AttrType * Attr,Expr * Exp,const NamedDecl * D,const CFGBlock * PredBlock,const CFGBlock * CurrBlock,Expr * BrE,bool Neg)1283 void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1284 Expr *Exp, const NamedDecl *D,
1285 const CFGBlock *PredBlock,
1286 const CFGBlock *CurrBlock,
1287 Expr *BrE, bool Neg) {
1288 // Find out which branch has the lock
1289 bool branch = false;
1290 if (CXXBoolLiteralExpr *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE))
1291 branch = BLE->getValue();
1292 else if (IntegerLiteral *ILE = dyn_cast_or_null<IntegerLiteral>(BrE))
1293 branch = ILE->getValue().getBoolValue();
1294
1295 int branchnum = branch ? 0 : 1;
1296 if (Neg)
1297 branchnum = !branchnum;
1298
1299 // If we've taken the trylock branch, then add the lock
1300 int i = 0;
1301 for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1302 SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1303 if (*SI == CurrBlock && i == branchnum)
1304 getMutexIDs(Mtxs, Attr, Exp, D);
1305 }
1306 }
1307
getStaticBooleanValue(Expr * E,bool & TCond)1308 static bool getStaticBooleanValue(Expr *E, bool &TCond) {
1309 if (isa<CXXNullPtrLiteralExpr>(E) || isa<GNUNullExpr>(E)) {
1310 TCond = false;
1311 return true;
1312 } else if (CXXBoolLiteralExpr *BLE = dyn_cast<CXXBoolLiteralExpr>(E)) {
1313 TCond = BLE->getValue();
1314 return true;
1315 } else if (IntegerLiteral *ILE = dyn_cast<IntegerLiteral>(E)) {
1316 TCond = ILE->getValue().getBoolValue();
1317 return true;
1318 } else if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
1319 return getStaticBooleanValue(CE->getSubExpr(), TCond);
1320 }
1321 return false;
1322 }
1323
1324
1325 // If Cond can be traced back to a function call, return the call expression.
1326 // The negate variable should be called with false, and will be set to true
1327 // if the function call is negated, e.g. if (!mu.tryLock(...))
getTrylockCallExpr(const Stmt * Cond,LocalVarContext C,bool & Negate)1328 const CallExpr* ThreadSafetyAnalyzer::getTrylockCallExpr(const Stmt *Cond,
1329 LocalVarContext C,
1330 bool &Negate) {
1331 if (!Cond)
1332 return nullptr;
1333
1334 if (const CallExpr *CallExp = dyn_cast<CallExpr>(Cond)) {
1335 return CallExp;
1336 }
1337 else if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) {
1338 return getTrylockCallExpr(PE->getSubExpr(), C, Negate);
1339 }
1340 else if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Cond)) {
1341 return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1342 }
1343 else if (const ExprWithCleanups* EWC = dyn_cast<ExprWithCleanups>(Cond)) {
1344 return getTrylockCallExpr(EWC->getSubExpr(), C, Negate);
1345 }
1346 else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1347 const Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1348 return getTrylockCallExpr(E, C, Negate);
1349 }
1350 else if (const UnaryOperator *UOP = dyn_cast<UnaryOperator>(Cond)) {
1351 if (UOP->getOpcode() == UO_LNot) {
1352 Negate = !Negate;
1353 return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1354 }
1355 return nullptr;
1356 }
1357 else if (const BinaryOperator *BOP = dyn_cast<BinaryOperator>(Cond)) {
1358 if (BOP->getOpcode() == BO_EQ || BOP->getOpcode() == BO_NE) {
1359 if (BOP->getOpcode() == BO_NE)
1360 Negate = !Negate;
1361
1362 bool TCond = false;
1363 if (getStaticBooleanValue(BOP->getRHS(), TCond)) {
1364 if (!TCond) Negate = !Negate;
1365 return getTrylockCallExpr(BOP->getLHS(), C, Negate);
1366 }
1367 TCond = false;
1368 if (getStaticBooleanValue(BOP->getLHS(), TCond)) {
1369 if (!TCond) Negate = !Negate;
1370 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1371 }
1372 return nullptr;
1373 }
1374 if (BOP->getOpcode() == BO_LAnd) {
1375 // LHS must have been evaluated in a different block.
1376 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1377 }
1378 if (BOP->getOpcode() == BO_LOr) {
1379 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1380 }
1381 return nullptr;
1382 }
1383 return nullptr;
1384 }
1385
1386
1387 /// \brief Find the lockset that holds on the edge between PredBlock
1388 /// and CurrBlock. The edge set is the exit set of PredBlock (passed
1389 /// as the ExitSet parameter) plus any trylocks, which are conditionally held.
getEdgeLockset(FactSet & Result,const FactSet & ExitSet,const CFGBlock * PredBlock,const CFGBlock * CurrBlock)1390 void ThreadSafetyAnalyzer::getEdgeLockset(FactSet& Result,
1391 const FactSet &ExitSet,
1392 const CFGBlock *PredBlock,
1393 const CFGBlock *CurrBlock) {
1394 Result = ExitSet;
1395
1396 const Stmt *Cond = PredBlock->getTerminatorCondition();
1397 if (!Cond)
1398 return;
1399
1400 bool Negate = false;
1401 const CFGBlockInfo *PredBlockInfo = &BlockInfo[PredBlock->getBlockID()];
1402 const LocalVarContext &LVarCtx = PredBlockInfo->ExitContext;
1403 StringRef CapDiagKind = "mutex";
1404
1405 CallExpr *Exp =
1406 const_cast<CallExpr*>(getTrylockCallExpr(Cond, LVarCtx, Negate));
1407 if (!Exp)
1408 return;
1409
1410 NamedDecl *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1411 if(!FunDecl || !FunDecl->hasAttrs())
1412 return;
1413
1414 CapExprSet ExclusiveLocksToAdd;
1415 CapExprSet SharedLocksToAdd;
1416
1417 // If the condition is a call to a Trylock function, then grab the attributes
1418 for (auto *Attr : FunDecl->attrs()) {
1419 switch (Attr->getKind()) {
1420 case attr::ExclusiveTrylockFunction: {
1421 ExclusiveTrylockFunctionAttr *A =
1422 cast<ExclusiveTrylockFunctionAttr>(Attr);
1423 getMutexIDs(ExclusiveLocksToAdd, A, Exp, FunDecl,
1424 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1425 CapDiagKind = ClassifyDiagnostic(A);
1426 break;
1427 }
1428 case attr::SharedTrylockFunction: {
1429 SharedTrylockFunctionAttr *A =
1430 cast<SharedTrylockFunctionAttr>(Attr);
1431 getMutexIDs(SharedLocksToAdd, A, Exp, FunDecl,
1432 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1433 CapDiagKind = ClassifyDiagnostic(A);
1434 break;
1435 }
1436 default:
1437 break;
1438 }
1439 }
1440
1441 // Add and remove locks.
1442 SourceLocation Loc = Exp->getExprLoc();
1443 for (const auto &ExclusiveLockToAdd : ExclusiveLocksToAdd)
1444 addLock(Result, llvm::make_unique<LockableFactEntry>(ExclusiveLockToAdd,
1445 LK_Exclusive, Loc),
1446 CapDiagKind);
1447 for (const auto &SharedLockToAdd : SharedLocksToAdd)
1448 addLock(Result, llvm::make_unique<LockableFactEntry>(SharedLockToAdd,
1449 LK_Shared, Loc),
1450 CapDiagKind);
1451 }
1452
1453 namespace {
1454 /// \brief We use this class to visit different types of expressions in
1455 /// CFGBlocks, and build up the lockset.
1456 /// An expression may cause us to add or remove locks from the lockset, or else
1457 /// output error messages related to missing locks.
1458 /// FIXME: In future, we may be able to not inherit from a visitor.
1459 class BuildLockset : public StmtVisitor<BuildLockset> {
1460 friend class ThreadSafetyAnalyzer;
1461
1462 ThreadSafetyAnalyzer *Analyzer;
1463 FactSet FSet;
1464 LocalVariableMap::Context LVarCtx;
1465 unsigned CtxIndex;
1466
1467 // helper functions
1468 void warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp, AccessKind AK,
1469 Expr *MutexExp, ProtectedOperationKind POK,
1470 StringRef DiagKind, SourceLocation Loc);
1471 void warnIfMutexHeld(const NamedDecl *D, const Expr *Exp, Expr *MutexExp,
1472 StringRef DiagKind);
1473
1474 void checkAccess(const Expr *Exp, AccessKind AK,
1475 ProtectedOperationKind POK = POK_VarAccess);
1476 void checkPtAccess(const Expr *Exp, AccessKind AK,
1477 ProtectedOperationKind POK = POK_VarAccess);
1478
1479 void handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD = nullptr);
1480
1481 public:
BuildLockset(ThreadSafetyAnalyzer * Anlzr,CFGBlockInfo & Info)1482 BuildLockset(ThreadSafetyAnalyzer *Anlzr, CFGBlockInfo &Info)
1483 : StmtVisitor<BuildLockset>(),
1484 Analyzer(Anlzr),
1485 FSet(Info.EntrySet),
1486 LVarCtx(Info.EntryContext),
1487 CtxIndex(Info.EntryIndex)
1488 {}
1489
1490 void VisitUnaryOperator(UnaryOperator *UO);
1491 void VisitBinaryOperator(BinaryOperator *BO);
1492 void VisitCastExpr(CastExpr *CE);
1493 void VisitCallExpr(CallExpr *Exp);
1494 void VisitCXXConstructExpr(CXXConstructExpr *Exp);
1495 void VisitDeclStmt(DeclStmt *S);
1496 };
1497 } // namespace
1498
1499 /// \brief Warn if the LSet does not contain a lock sufficient to protect access
1500 /// of at least the passed in AccessKind.
warnIfMutexNotHeld(const NamedDecl * D,const Expr * Exp,AccessKind AK,Expr * MutexExp,ProtectedOperationKind POK,StringRef DiagKind,SourceLocation Loc)1501 void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp,
1502 AccessKind AK, Expr *MutexExp,
1503 ProtectedOperationKind POK,
1504 StringRef DiagKind, SourceLocation Loc) {
1505 LockKind LK = getLockKindFromAccessKind(AK);
1506
1507 CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1508 if (Cp.isInvalid()) {
1509 warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1510 return;
1511 } else if (Cp.shouldIgnore()) {
1512 return;
1513 }
1514
1515 if (Cp.negative()) {
1516 // Negative capabilities act like locks excluded
1517 FactEntry *LDat = FSet.findLock(Analyzer->FactMan, !Cp);
1518 if (LDat) {
1519 Analyzer->Handler.handleFunExcludesLock(
1520 DiagKind, D->getNameAsString(), (!Cp).toString(), Loc);
1521 return;
1522 }
1523
1524 // If this does not refer to a negative capability in the same class,
1525 // then stop here.
1526 if (!Analyzer->inCurrentScope(Cp))
1527 return;
1528
1529 // Otherwise the negative requirement must be propagated to the caller.
1530 LDat = FSet.findLock(Analyzer->FactMan, Cp);
1531 if (!LDat) {
1532 Analyzer->Handler.handleMutexNotHeld("", D, POK, Cp.toString(),
1533 LK_Shared, Loc);
1534 }
1535 return;
1536 }
1537
1538 FactEntry* LDat = FSet.findLockUniv(Analyzer->FactMan, Cp);
1539 bool NoError = true;
1540 if (!LDat) {
1541 // No exact match found. Look for a partial match.
1542 LDat = FSet.findPartialMatch(Analyzer->FactMan, Cp);
1543 if (LDat) {
1544 // Warn that there's no precise match.
1545 std::string PartMatchStr = LDat->toString();
1546 StringRef PartMatchName(PartMatchStr);
1547 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1548 LK, Loc, &PartMatchName);
1549 } else {
1550 // Warn that there's no match at all.
1551 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1552 LK, Loc);
1553 }
1554 NoError = false;
1555 }
1556 // Make sure the mutex we found is the right kind.
1557 if (NoError && LDat && !LDat->isAtLeast(LK)) {
1558 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1559 LK, Loc);
1560 }
1561 }
1562
1563 /// \brief Warn if the LSet contains the given lock.
warnIfMutexHeld(const NamedDecl * D,const Expr * Exp,Expr * MutexExp,StringRef DiagKind)1564 void BuildLockset::warnIfMutexHeld(const NamedDecl *D, const Expr *Exp,
1565 Expr *MutexExp, StringRef DiagKind) {
1566 CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1567 if (Cp.isInvalid()) {
1568 warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1569 return;
1570 } else if (Cp.shouldIgnore()) {
1571 return;
1572 }
1573
1574 FactEntry* LDat = FSet.findLock(Analyzer->FactMan, Cp);
1575 if (LDat) {
1576 Analyzer->Handler.handleFunExcludesLock(
1577 DiagKind, D->getNameAsString(), Cp.toString(), Exp->getExprLoc());
1578 }
1579 }
1580
1581 /// \brief Checks guarded_by and pt_guarded_by attributes.
1582 /// Whenever we identify an access (read or write) to a DeclRefExpr that is
1583 /// marked with guarded_by, we must ensure the appropriate mutexes are held.
1584 /// Similarly, we check if the access is to an expression that dereferences
1585 /// a pointer marked with pt_guarded_by.
checkAccess(const Expr * Exp,AccessKind AK,ProtectedOperationKind POK)1586 void BuildLockset::checkAccess(const Expr *Exp, AccessKind AK,
1587 ProtectedOperationKind POK) {
1588 Exp = Exp->IgnoreParenCasts();
1589
1590 SourceLocation Loc = Exp->getExprLoc();
1591
1592 // Local variables of reference type cannot be re-assigned;
1593 // map them to their initializer.
1594 while (const auto *DRE = dyn_cast<DeclRefExpr>(Exp)) {
1595 const auto *VD = dyn_cast<VarDecl>(DRE->getDecl()->getCanonicalDecl());
1596 if (VD && VD->isLocalVarDecl() && VD->getType()->isReferenceType()) {
1597 if (const auto *E = VD->getInit()) {
1598 Exp = E;
1599 continue;
1600 }
1601 }
1602 break;
1603 }
1604
1605 if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp)) {
1606 // For dereferences
1607 if (UO->getOpcode() == clang::UO_Deref)
1608 checkPtAccess(UO->getSubExpr(), AK, POK);
1609 return;
1610 }
1611
1612 if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(Exp)) {
1613 checkPtAccess(AE->getLHS(), AK, POK);
1614 return;
1615 }
1616
1617 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
1618 if (ME->isArrow())
1619 checkPtAccess(ME->getBase(), AK, POK);
1620 else
1621 checkAccess(ME->getBase(), AK, POK);
1622 }
1623
1624 const ValueDecl *D = getValueDecl(Exp);
1625 if (!D || !D->hasAttrs())
1626 return;
1627
1628 if (D->hasAttr<GuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan)) {
1629 Analyzer->Handler.handleNoMutexHeld("mutex", D, POK, AK, Loc);
1630 }
1631
1632 for (const auto *I : D->specific_attrs<GuardedByAttr>())
1633 warnIfMutexNotHeld(D, Exp, AK, I->getArg(), POK,
1634 ClassifyDiagnostic(I), Loc);
1635 }
1636
1637
1638 /// \brief Checks pt_guarded_by and pt_guarded_var attributes.
1639 /// POK is the same operationKind that was passed to checkAccess.
checkPtAccess(const Expr * Exp,AccessKind AK,ProtectedOperationKind POK)1640 void BuildLockset::checkPtAccess(const Expr *Exp, AccessKind AK,
1641 ProtectedOperationKind POK) {
1642 while (true) {
1643 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Exp)) {
1644 Exp = PE->getSubExpr();
1645 continue;
1646 }
1647 if (const CastExpr *CE = dyn_cast<CastExpr>(Exp)) {
1648 if (CE->getCastKind() == CK_ArrayToPointerDecay) {
1649 // If it's an actual array, and not a pointer, then it's elements
1650 // are protected by GUARDED_BY, not PT_GUARDED_BY;
1651 checkAccess(CE->getSubExpr(), AK, POK);
1652 return;
1653 }
1654 Exp = CE->getSubExpr();
1655 continue;
1656 }
1657 break;
1658 }
1659
1660 // Pass by reference warnings are under a different flag.
1661 ProtectedOperationKind PtPOK = POK_VarDereference;
1662 if (POK == POK_PassByRef) PtPOK = POK_PtPassByRef;
1663
1664 const ValueDecl *D = getValueDecl(Exp);
1665 if (!D || !D->hasAttrs())
1666 return;
1667
1668 if (D->hasAttr<PtGuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan))
1669 Analyzer->Handler.handleNoMutexHeld("mutex", D, PtPOK, AK,
1670 Exp->getExprLoc());
1671
1672 for (auto const *I : D->specific_attrs<PtGuardedByAttr>())
1673 warnIfMutexNotHeld(D, Exp, AK, I->getArg(), PtPOK,
1674 ClassifyDiagnostic(I), Exp->getExprLoc());
1675 }
1676
1677 /// \brief Process a function call, method call, constructor call,
1678 /// or destructor call. This involves looking at the attributes on the
1679 /// corresponding function/method/constructor/destructor, issuing warnings,
1680 /// and updating the locksets accordingly.
1681 ///
1682 /// FIXME: For classes annotated with one of the guarded annotations, we need
1683 /// to treat const method calls as reads and non-const method calls as writes,
1684 /// and check that the appropriate locks are held. Non-const method calls with
1685 /// the same signature as const method calls can be also treated as reads.
1686 ///
handleCall(Expr * Exp,const NamedDecl * D,VarDecl * VD)1687 void BuildLockset::handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD) {
1688 SourceLocation Loc = Exp->getExprLoc();
1689 CapExprSet ExclusiveLocksToAdd, SharedLocksToAdd;
1690 CapExprSet ExclusiveLocksToRemove, SharedLocksToRemove, GenericLocksToRemove;
1691 CapExprSet ScopedExclusiveReqs, ScopedSharedReqs;
1692 StringRef CapDiagKind = "mutex";
1693
1694 // Figure out if we're calling the constructor of scoped lockable class
1695 bool isScopedVar = false;
1696 if (VD) {
1697 if (const CXXConstructorDecl *CD = dyn_cast<const CXXConstructorDecl>(D)) {
1698 const CXXRecordDecl* PD = CD->getParent();
1699 if (PD && PD->hasAttr<ScopedLockableAttr>())
1700 isScopedVar = true;
1701 }
1702 }
1703
1704 for(Attr *Atconst : D->attrs()) {
1705 Attr* At = const_cast<Attr*>(Atconst);
1706 switch (At->getKind()) {
1707 // When we encounter a lock function, we need to add the lock to our
1708 // lockset.
1709 case attr::AcquireCapability: {
1710 auto *A = cast<AcquireCapabilityAttr>(At);
1711 Analyzer->getMutexIDs(A->isShared() ? SharedLocksToAdd
1712 : ExclusiveLocksToAdd,
1713 A, Exp, D, VD);
1714
1715 CapDiagKind = ClassifyDiagnostic(A);
1716 break;
1717 }
1718
1719 // An assert will add a lock to the lockset, but will not generate
1720 // a warning if it is already there, and will not generate a warning
1721 // if it is not removed.
1722 case attr::AssertExclusiveLock: {
1723 AssertExclusiveLockAttr *A = cast<AssertExclusiveLockAttr>(At);
1724
1725 CapExprSet AssertLocks;
1726 Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1727 for (const auto &AssertLock : AssertLocks)
1728 Analyzer->addLock(FSet,
1729 llvm::make_unique<LockableFactEntry>(
1730 AssertLock, LK_Exclusive, Loc, false, true),
1731 ClassifyDiagnostic(A));
1732 break;
1733 }
1734 case attr::AssertSharedLock: {
1735 AssertSharedLockAttr *A = cast<AssertSharedLockAttr>(At);
1736
1737 CapExprSet AssertLocks;
1738 Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1739 for (const auto &AssertLock : AssertLocks)
1740 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1741 AssertLock, LK_Shared, Loc, false, true),
1742 ClassifyDiagnostic(A));
1743 break;
1744 }
1745
1746 // When we encounter an unlock function, we need to remove unlocked
1747 // mutexes from the lockset, and flag a warning if they are not there.
1748 case attr::ReleaseCapability: {
1749 auto *A = cast<ReleaseCapabilityAttr>(At);
1750 if (A->isGeneric())
1751 Analyzer->getMutexIDs(GenericLocksToRemove, A, Exp, D, VD);
1752 else if (A->isShared())
1753 Analyzer->getMutexIDs(SharedLocksToRemove, A, Exp, D, VD);
1754 else
1755 Analyzer->getMutexIDs(ExclusiveLocksToRemove, A, Exp, D, VD);
1756
1757 CapDiagKind = ClassifyDiagnostic(A);
1758 break;
1759 }
1760
1761 case attr::RequiresCapability: {
1762 RequiresCapabilityAttr *A = cast<RequiresCapabilityAttr>(At);
1763 for (auto *Arg : A->args()) {
1764 warnIfMutexNotHeld(D, Exp, A->isShared() ? AK_Read : AK_Written, Arg,
1765 POK_FunctionCall, ClassifyDiagnostic(A),
1766 Exp->getExprLoc());
1767 // use for adopting a lock
1768 if (isScopedVar) {
1769 Analyzer->getMutexIDs(A->isShared() ? ScopedSharedReqs
1770 : ScopedExclusiveReqs,
1771 A, Exp, D, VD);
1772 }
1773 }
1774 break;
1775 }
1776
1777 case attr::LocksExcluded: {
1778 LocksExcludedAttr *A = cast<LocksExcludedAttr>(At);
1779 for (auto *Arg : A->args())
1780 warnIfMutexHeld(D, Exp, Arg, ClassifyDiagnostic(A));
1781 break;
1782 }
1783
1784 // Ignore attributes unrelated to thread-safety
1785 default:
1786 break;
1787 }
1788 }
1789
1790 // Add locks.
1791 for (const auto &M : ExclusiveLocksToAdd)
1792 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1793 M, LK_Exclusive, Loc, isScopedVar),
1794 CapDiagKind);
1795 for (const auto &M : SharedLocksToAdd)
1796 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1797 M, LK_Shared, Loc, isScopedVar),
1798 CapDiagKind);
1799
1800 if (isScopedVar) {
1801 // Add the managing object as a dummy mutex, mapped to the underlying mutex.
1802 SourceLocation MLoc = VD->getLocation();
1803 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue, VD->getLocation());
1804 // FIXME: does this store a pointer to DRE?
1805 CapabilityExpr Scp = Analyzer->SxBuilder.translateAttrExpr(&DRE, nullptr);
1806
1807 std::copy(ScopedExclusiveReqs.begin(), ScopedExclusiveReqs.end(),
1808 std::back_inserter(ExclusiveLocksToAdd));
1809 std::copy(ScopedSharedReqs.begin(), ScopedSharedReqs.end(),
1810 std::back_inserter(SharedLocksToAdd));
1811 Analyzer->addLock(FSet,
1812 llvm::make_unique<ScopedLockableFactEntry>(
1813 Scp, MLoc, ExclusiveLocksToAdd, SharedLocksToAdd),
1814 CapDiagKind);
1815 }
1816
1817 // Remove locks.
1818 // FIXME -- should only fully remove if the attribute refers to 'this'.
1819 bool Dtor = isa<CXXDestructorDecl>(D);
1820 for (const auto &M : ExclusiveLocksToRemove)
1821 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Exclusive, CapDiagKind);
1822 for (const auto &M : SharedLocksToRemove)
1823 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Shared, CapDiagKind);
1824 for (const auto &M : GenericLocksToRemove)
1825 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Generic, CapDiagKind);
1826 }
1827
1828
1829 /// \brief For unary operations which read and write a variable, we need to
1830 /// check whether we hold any required mutexes. Reads are checked in
1831 /// VisitCastExpr.
VisitUnaryOperator(UnaryOperator * UO)1832 void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
1833 switch (UO->getOpcode()) {
1834 case clang::UO_PostDec:
1835 case clang::UO_PostInc:
1836 case clang::UO_PreDec:
1837 case clang::UO_PreInc: {
1838 checkAccess(UO->getSubExpr(), AK_Written);
1839 break;
1840 }
1841 default:
1842 break;
1843 }
1844 }
1845
1846 /// For binary operations which assign to a variable (writes), we need to check
1847 /// whether we hold any required mutexes.
1848 /// FIXME: Deal with non-primitive types.
VisitBinaryOperator(BinaryOperator * BO)1849 void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
1850 if (!BO->isAssignmentOp())
1851 return;
1852
1853 // adjust the context
1854 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
1855
1856 checkAccess(BO->getLHS(), AK_Written);
1857 }
1858
1859
1860 /// Whenever we do an LValue to Rvalue cast, we are reading a variable and
1861 /// need to ensure we hold any required mutexes.
1862 /// FIXME: Deal with non-primitive types.
VisitCastExpr(CastExpr * CE)1863 void BuildLockset::VisitCastExpr(CastExpr *CE) {
1864 if (CE->getCastKind() != CK_LValueToRValue)
1865 return;
1866 checkAccess(CE->getSubExpr(), AK_Read);
1867 }
1868
1869
VisitCallExpr(CallExpr * Exp)1870 void BuildLockset::VisitCallExpr(CallExpr *Exp) {
1871 bool ExamineArgs = true;
1872 bool OperatorFun = false;
1873
1874 if (CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(Exp)) {
1875 MemberExpr *ME = dyn_cast<MemberExpr>(CE->getCallee());
1876 // ME can be null when calling a method pointer
1877 CXXMethodDecl *MD = CE->getMethodDecl();
1878
1879 if (ME && MD) {
1880 if (ME->isArrow()) {
1881 if (MD->isConst()) {
1882 checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1883 } else { // FIXME -- should be AK_Written
1884 checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1885 }
1886 } else {
1887 if (MD->isConst())
1888 checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1889 else // FIXME -- should be AK_Written
1890 checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1891 }
1892 }
1893 } else if (CXXOperatorCallExpr *OE = dyn_cast<CXXOperatorCallExpr>(Exp)) {
1894 OperatorFun = true;
1895
1896 auto OEop = OE->getOperator();
1897 switch (OEop) {
1898 case OO_Equal: {
1899 ExamineArgs = false;
1900 const Expr *Target = OE->getArg(0);
1901 const Expr *Source = OE->getArg(1);
1902 checkAccess(Target, AK_Written);
1903 checkAccess(Source, AK_Read);
1904 break;
1905 }
1906 case OO_Star:
1907 case OO_Arrow:
1908 case OO_Subscript: {
1909 const Expr *Obj = OE->getArg(0);
1910 checkAccess(Obj, AK_Read);
1911 if (!(OEop == OO_Star && OE->getNumArgs() > 1)) {
1912 // Grrr. operator* can be multiplication...
1913 checkPtAccess(Obj, AK_Read);
1914 }
1915 break;
1916 }
1917 default: {
1918 // TODO: get rid of this, and rely on pass-by-ref instead.
1919 const Expr *Obj = OE->getArg(0);
1920 checkAccess(Obj, AK_Read);
1921 break;
1922 }
1923 }
1924 }
1925
1926 if (ExamineArgs) {
1927 if (FunctionDecl *FD = Exp->getDirectCallee()) {
1928
1929 // NO_THREAD_SAFETY_ANALYSIS does double duty here. Normally it
1930 // only turns off checking within the body of a function, but we also
1931 // use it to turn off checking in arguments to the function. This
1932 // could result in some false negatives, but the alternative is to
1933 // create yet another attribute.
1934 //
1935 if (!FD->hasAttr<NoThreadSafetyAnalysisAttr>()) {
1936 unsigned Fn = FD->getNumParams();
1937 unsigned Cn = Exp->getNumArgs();
1938 unsigned Skip = 0;
1939
1940 unsigned i = 0;
1941 if (OperatorFun) {
1942 if (isa<CXXMethodDecl>(FD)) {
1943 // First arg in operator call is implicit self argument,
1944 // and doesn't appear in the FunctionDecl.
1945 Skip = 1;
1946 Cn--;
1947 } else {
1948 // Ignore the first argument of operators; it's been checked above.
1949 i = 1;
1950 }
1951 }
1952 // Ignore default arguments
1953 unsigned n = (Fn < Cn) ? Fn : Cn;
1954
1955 for (; i < n; ++i) {
1956 ParmVarDecl* Pvd = FD->getParamDecl(i);
1957 Expr* Arg = Exp->getArg(i+Skip);
1958 QualType Qt = Pvd->getType();
1959 if (Qt->isReferenceType())
1960 checkAccess(Arg, AK_Read, POK_PassByRef);
1961 }
1962 }
1963 }
1964 }
1965
1966 NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1967 if(!D || !D->hasAttrs())
1968 return;
1969 handleCall(Exp, D);
1970 }
1971
VisitCXXConstructExpr(CXXConstructExpr * Exp)1972 void BuildLockset::VisitCXXConstructExpr(CXXConstructExpr *Exp) {
1973 const CXXConstructorDecl *D = Exp->getConstructor();
1974 if (D && D->isCopyConstructor()) {
1975 const Expr* Source = Exp->getArg(0);
1976 checkAccess(Source, AK_Read);
1977 }
1978 // FIXME -- only handles constructors in DeclStmt below.
1979 }
1980
VisitDeclStmt(DeclStmt * S)1981 void BuildLockset::VisitDeclStmt(DeclStmt *S) {
1982 // adjust the context
1983 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
1984
1985 for (auto *D : S->getDeclGroup()) {
1986 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(D)) {
1987 Expr *E = VD->getInit();
1988 // handle constructors that involve temporaries
1989 if (ExprWithCleanups *EWC = dyn_cast_or_null<ExprWithCleanups>(E))
1990 E = EWC->getSubExpr();
1991
1992 if (CXXConstructExpr *CE = dyn_cast_or_null<CXXConstructExpr>(E)) {
1993 NamedDecl *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
1994 if (!CtorD || !CtorD->hasAttrs())
1995 return;
1996 handleCall(CE, CtorD, VD);
1997 }
1998 }
1999 }
2000 }
2001
2002
2003
2004 /// \brief Compute the intersection of two locksets and issue warnings for any
2005 /// locks in the symmetric difference.
2006 ///
2007 /// This function is used at a merge point in the CFG when comparing the lockset
2008 /// of each branch being merged. For example, given the following sequence:
2009 /// A; if () then B; else C; D; we need to check that the lockset after B and C
2010 /// are the same. In the event of a difference, we use the intersection of these
2011 /// two locksets at the start of D.
2012 ///
2013 /// \param FSet1 The first lockset.
2014 /// \param FSet2 The second lockset.
2015 /// \param JoinLoc The location of the join point for error reporting
2016 /// \param LEK1 The error message to report if a mutex is missing from LSet1
2017 /// \param LEK2 The error message to report if a mutex is missing from Lset2
intersectAndWarn(FactSet & FSet1,const FactSet & FSet2,SourceLocation JoinLoc,LockErrorKind LEK1,LockErrorKind LEK2,bool Modify)2018 void ThreadSafetyAnalyzer::intersectAndWarn(FactSet &FSet1,
2019 const FactSet &FSet2,
2020 SourceLocation JoinLoc,
2021 LockErrorKind LEK1,
2022 LockErrorKind LEK2,
2023 bool Modify) {
2024 FactSet FSet1Orig = FSet1;
2025
2026 // Find locks in FSet2 that conflict or are not in FSet1, and warn.
2027 for (const auto &Fact : FSet2) {
2028 const FactEntry *LDat1 = nullptr;
2029 const FactEntry *LDat2 = &FactMan[Fact];
2030 FactSet::iterator Iter1 = FSet1.findLockIter(FactMan, *LDat2);
2031 if (Iter1 != FSet1.end()) LDat1 = &FactMan[*Iter1];
2032
2033 if (LDat1) {
2034 if (LDat1->kind() != LDat2->kind()) {
2035 Handler.handleExclusiveAndShared("mutex", LDat2->toString(),
2036 LDat2->loc(), LDat1->loc());
2037 if (Modify && LDat1->kind() != LK_Exclusive) {
2038 // Take the exclusive lock, which is the one in FSet2.
2039 *Iter1 = Fact;
2040 }
2041 }
2042 else if (Modify && LDat1->asserted() && !LDat2->asserted()) {
2043 // The non-asserted lock in FSet2 is the one we want to track.
2044 *Iter1 = Fact;
2045 }
2046 } else {
2047 LDat2->handleRemovalFromIntersection(FSet2, FactMan, JoinLoc, LEK1,
2048 Handler);
2049 }
2050 }
2051
2052 // Find locks in FSet1 that are not in FSet2, and remove them.
2053 for (const auto &Fact : FSet1Orig) {
2054 const FactEntry *LDat1 = &FactMan[Fact];
2055 const FactEntry *LDat2 = FSet2.findLock(FactMan, *LDat1);
2056
2057 if (!LDat2) {
2058 LDat1->handleRemovalFromIntersection(FSet1Orig, FactMan, JoinLoc, LEK2,
2059 Handler);
2060 if (Modify)
2061 FSet1.removeLock(FactMan, *LDat1);
2062 }
2063 }
2064 }
2065
2066
2067 // Return true if block B never continues to its successors.
neverReturns(const CFGBlock * B)2068 static bool neverReturns(const CFGBlock *B) {
2069 if (B->hasNoReturnElement())
2070 return true;
2071 if (B->empty())
2072 return false;
2073
2074 CFGElement Last = B->back();
2075 if (Optional<CFGStmt> S = Last.getAs<CFGStmt>()) {
2076 if (isa<CXXThrowExpr>(S->getStmt()))
2077 return true;
2078 }
2079 return false;
2080 }
2081
2082
2083 /// \brief Check a function's CFG for thread-safety violations.
2084 ///
2085 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2086 /// at the end of each block, and issue warnings for thread safety violations.
2087 /// Each block in the CFG is traversed exactly once.
runAnalysis(AnalysisDeclContext & AC)2088 void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
2089 // TODO: this whole function needs be rewritten as a visitor for CFGWalker.
2090 // For now, we just use the walker to set things up.
2091 threadSafety::CFGWalker walker;
2092 if (!walker.init(AC))
2093 return;
2094
2095 // AC.dumpCFG(true);
2096 // threadSafety::printSCFG(walker);
2097
2098 CFG *CFGraph = walker.getGraph();
2099 const NamedDecl *D = walker.getDecl();
2100 const FunctionDecl *CurrentFunction = dyn_cast<FunctionDecl>(D);
2101 CurrentMethod = dyn_cast<CXXMethodDecl>(D);
2102
2103 if (D->hasAttr<NoThreadSafetyAnalysisAttr>())
2104 return;
2105
2106 // FIXME: Do something a bit more intelligent inside constructor and
2107 // destructor code. Constructors and destructors must assume unique access
2108 // to 'this', so checks on member variable access is disabled, but we should
2109 // still enable checks on other objects.
2110 if (isa<CXXConstructorDecl>(D))
2111 return; // Don't check inside constructors.
2112 if (isa<CXXDestructorDecl>(D))
2113 return; // Don't check inside destructors.
2114
2115 Handler.enterFunction(CurrentFunction);
2116
2117 BlockInfo.resize(CFGraph->getNumBlockIDs(),
2118 CFGBlockInfo::getEmptyBlockInfo(LocalVarMap));
2119
2120 // We need to explore the CFG via a "topological" ordering.
2121 // That way, we will be guaranteed to have information about required
2122 // predecessor locksets when exploring a new block.
2123 const PostOrderCFGView *SortedGraph = walker.getSortedGraph();
2124 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
2125
2126 // Mark entry block as reachable
2127 BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
2128
2129 // Compute SSA names for local variables
2130 LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
2131
2132 // Fill in source locations for all CFGBlocks.
2133 findBlockLocations(CFGraph, SortedGraph, BlockInfo);
2134
2135 CapExprSet ExclusiveLocksAcquired;
2136 CapExprSet SharedLocksAcquired;
2137 CapExprSet LocksReleased;
2138
2139 // Add locks from exclusive_locks_required and shared_locks_required
2140 // to initial lockset. Also turn off checking for lock and unlock functions.
2141 // FIXME: is there a more intelligent way to check lock/unlock functions?
2142 if (!SortedGraph->empty() && D->hasAttrs()) {
2143 const CFGBlock *FirstBlock = *SortedGraph->begin();
2144 FactSet &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
2145
2146 CapExprSet ExclusiveLocksToAdd;
2147 CapExprSet SharedLocksToAdd;
2148 StringRef CapDiagKind = "mutex";
2149
2150 SourceLocation Loc = D->getLocation();
2151 for (const auto *Attr : D->attrs()) {
2152 Loc = Attr->getLocation();
2153 if (const auto *A = dyn_cast<RequiresCapabilityAttr>(Attr)) {
2154 getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
2155 nullptr, D);
2156 CapDiagKind = ClassifyDiagnostic(A);
2157 } else if (const auto *A = dyn_cast<ReleaseCapabilityAttr>(Attr)) {
2158 // UNLOCK_FUNCTION() is used to hide the underlying lock implementation.
2159 // We must ignore such methods.
2160 if (A->args_size() == 0)
2161 return;
2162 // FIXME -- deal with exclusive vs. shared unlock functions?
2163 getMutexIDs(ExclusiveLocksToAdd, A, nullptr, D);
2164 getMutexIDs(LocksReleased, A, nullptr, D);
2165 CapDiagKind = ClassifyDiagnostic(A);
2166 } else if (const auto *A = dyn_cast<AcquireCapabilityAttr>(Attr)) {
2167 if (A->args_size() == 0)
2168 return;
2169 getMutexIDs(A->isShared() ? SharedLocksAcquired
2170 : ExclusiveLocksAcquired,
2171 A, nullptr, D);
2172 CapDiagKind = ClassifyDiagnostic(A);
2173 } else if (isa<ExclusiveTrylockFunctionAttr>(Attr)) {
2174 // Don't try to check trylock functions for now
2175 return;
2176 } else if (isa<SharedTrylockFunctionAttr>(Attr)) {
2177 // Don't try to check trylock functions for now
2178 return;
2179 }
2180 }
2181
2182 // FIXME -- Loc can be wrong here.
2183 for (const auto &Mu : ExclusiveLocksToAdd) {
2184 auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Exclusive, Loc);
2185 Entry->setDeclared(true);
2186 addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2187 }
2188 for (const auto &Mu : SharedLocksToAdd) {
2189 auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Shared, Loc);
2190 Entry->setDeclared(true);
2191 addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2192 }
2193 }
2194
2195 for (const auto *CurrBlock : *SortedGraph) {
2196 int CurrBlockID = CurrBlock->getBlockID();
2197 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
2198
2199 // Use the default initial lockset in case there are no predecessors.
2200 VisitedBlocks.insert(CurrBlock);
2201
2202 // Iterate through the predecessor blocks and warn if the lockset for all
2203 // predecessors is not the same. We take the entry lockset of the current
2204 // block to be the intersection of all previous locksets.
2205 // FIXME: By keeping the intersection, we may output more errors in future
2206 // for a lock which is not in the intersection, but was in the union. We
2207 // may want to also keep the union in future. As an example, let's say
2208 // the intersection contains Mutex L, and the union contains L and M.
2209 // Later we unlock M. At this point, we would output an error because we
2210 // never locked M; although the real error is probably that we forgot to
2211 // lock M on all code paths. Conversely, let's say that later we lock M.
2212 // In this case, we should compare against the intersection instead of the
2213 // union because the real error is probably that we forgot to unlock M on
2214 // all code paths.
2215 bool LocksetInitialized = false;
2216 SmallVector<CFGBlock *, 8> SpecialBlocks;
2217 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
2218 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
2219
2220 // if *PI -> CurrBlock is a back edge
2221 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI))
2222 continue;
2223
2224 int PrevBlockID = (*PI)->getBlockID();
2225 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2226
2227 // Ignore edges from blocks that can't return.
2228 if (neverReturns(*PI) || !PrevBlockInfo->Reachable)
2229 continue;
2230
2231 // Okay, we can reach this block from the entry.
2232 CurrBlockInfo->Reachable = true;
2233
2234 // If the previous block ended in a 'continue' or 'break' statement, then
2235 // a difference in locksets is probably due to a bug in that block, rather
2236 // than in some other predecessor. In that case, keep the other
2237 // predecessor's lockset.
2238 if (const Stmt *Terminator = (*PI)->getTerminator()) {
2239 if (isa<ContinueStmt>(Terminator) || isa<BreakStmt>(Terminator)) {
2240 SpecialBlocks.push_back(*PI);
2241 continue;
2242 }
2243 }
2244
2245 FactSet PrevLockset;
2246 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
2247
2248 if (!LocksetInitialized) {
2249 CurrBlockInfo->EntrySet = PrevLockset;
2250 LocksetInitialized = true;
2251 } else {
2252 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2253 CurrBlockInfo->EntryLoc,
2254 LEK_LockedSomePredecessors);
2255 }
2256 }
2257
2258 // Skip rest of block if it's not reachable.
2259 if (!CurrBlockInfo->Reachable)
2260 continue;
2261
2262 // Process continue and break blocks. Assume that the lockset for the
2263 // resulting block is unaffected by any discrepancies in them.
2264 for (const auto *PrevBlock : SpecialBlocks) {
2265 int PrevBlockID = PrevBlock->getBlockID();
2266 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2267
2268 if (!LocksetInitialized) {
2269 CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
2270 LocksetInitialized = true;
2271 } else {
2272 // Determine whether this edge is a loop terminator for diagnostic
2273 // purposes. FIXME: A 'break' statement might be a loop terminator, but
2274 // it might also be part of a switch. Also, a subsequent destructor
2275 // might add to the lockset, in which case the real issue might be a
2276 // double lock on the other path.
2277 const Stmt *Terminator = PrevBlock->getTerminator();
2278 bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
2279
2280 FactSet PrevLockset;
2281 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet,
2282 PrevBlock, CurrBlock);
2283
2284 // Do not update EntrySet.
2285 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2286 PrevBlockInfo->ExitLoc,
2287 IsLoop ? LEK_LockedSomeLoopIterations
2288 : LEK_LockedSomePredecessors,
2289 false);
2290 }
2291 }
2292
2293 BuildLockset LocksetBuilder(this, *CurrBlockInfo);
2294
2295 // Visit all the statements in the basic block.
2296 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
2297 BE = CurrBlock->end(); BI != BE; ++BI) {
2298 switch (BI->getKind()) {
2299 case CFGElement::Statement: {
2300 CFGStmt CS = BI->castAs<CFGStmt>();
2301 LocksetBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
2302 break;
2303 }
2304 // Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
2305 case CFGElement::AutomaticObjectDtor: {
2306 CFGAutomaticObjDtor AD = BI->castAs<CFGAutomaticObjDtor>();
2307 CXXDestructorDecl *DD = const_cast<CXXDestructorDecl *>(
2308 AD.getDestructorDecl(AC.getASTContext()));
2309 if (!DD->hasAttrs())
2310 break;
2311
2312 // Create a dummy expression,
2313 VarDecl *VD = const_cast<VarDecl*>(AD.getVarDecl());
2314 DeclRefExpr DRE(VD, false, VD->getType().getNonReferenceType(),
2315 VK_LValue, AD.getTriggerStmt()->getLocEnd());
2316 LocksetBuilder.handleCall(&DRE, DD);
2317 break;
2318 }
2319 default:
2320 break;
2321 }
2322 }
2323 CurrBlockInfo->ExitSet = LocksetBuilder.FSet;
2324
2325 // For every back edge from CurrBlock (the end of the loop) to another block
2326 // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
2327 // the one held at the beginning of FirstLoopBlock. We can look up the
2328 // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
2329 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
2330 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
2331
2332 // if CurrBlock -> *SI is *not* a back edge
2333 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
2334 continue;
2335
2336 CFGBlock *FirstLoopBlock = *SI;
2337 CFGBlockInfo *PreLoop = &BlockInfo[FirstLoopBlock->getBlockID()];
2338 CFGBlockInfo *LoopEnd = &BlockInfo[CurrBlockID];
2339 intersectAndWarn(LoopEnd->ExitSet, PreLoop->EntrySet,
2340 PreLoop->EntryLoc,
2341 LEK_LockedSomeLoopIterations,
2342 false);
2343 }
2344 }
2345
2346 CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
2347 CFGBlockInfo *Final = &BlockInfo[CFGraph->getExit().getBlockID()];
2348
2349 // Skip the final check if the exit block is unreachable.
2350 if (!Final->Reachable)
2351 return;
2352
2353 // By default, we expect all locks held on entry to be held on exit.
2354 FactSet ExpectedExitSet = Initial->EntrySet;
2355
2356 // Adjust the expected exit set by adding or removing locks, as declared
2357 // by *-LOCK_FUNCTION and UNLOCK_FUNCTION. The intersect below will then
2358 // issue the appropriate warning.
2359 // FIXME: the location here is not quite right.
2360 for (const auto &Lock : ExclusiveLocksAcquired)
2361 ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2362 Lock, LK_Exclusive, D->getLocation()));
2363 for (const auto &Lock : SharedLocksAcquired)
2364 ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2365 Lock, LK_Shared, D->getLocation()));
2366 for (const auto &Lock : LocksReleased)
2367 ExpectedExitSet.removeLock(FactMan, Lock);
2368
2369 // FIXME: Should we call this function for all blocks which exit the function?
2370 intersectAndWarn(ExpectedExitSet, Final->ExitSet,
2371 Final->ExitLoc,
2372 LEK_LockedAtEndOfFunction,
2373 LEK_NotLockedAtEndOfFunction,
2374 false);
2375
2376 Handler.leaveFunction(CurrentFunction);
2377 }
2378
2379
2380 /// \brief Check a function's CFG for thread-safety violations.
2381 ///
2382 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2383 /// at the end of each block, and issue warnings for thread safety violations.
2384 /// Each block in the CFG is traversed exactly once.
runThreadSafetyAnalysis(AnalysisDeclContext & AC,ThreadSafetyHandler & Handler,BeforeSet ** BSet)2385 void threadSafety::runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2386 ThreadSafetyHandler &Handler,
2387 BeforeSet **BSet) {
2388 if (!*BSet)
2389 *BSet = new BeforeSet;
2390 ThreadSafetyAnalyzer Analyzer(Handler, *BSet);
2391 Analyzer.runAnalysis(AC);
2392 }
2393
threadSafetyCleanup(BeforeSet * Cache)2394 void threadSafety::threadSafetyCleanup(BeforeSet *Cache) { delete Cache; }
2395
2396 /// \brief Helper function that returns a LockKind required for the given level
2397 /// of access.
getLockKindFromAccessKind(AccessKind AK)2398 LockKind threadSafety::getLockKindFromAccessKind(AccessKind AK) {
2399 switch (AK) {
2400 case AK_Read :
2401 return LK_Shared;
2402 case AK_Written :
2403 return LK_Exclusive;
2404 }
2405 llvm_unreachable("Unknown AccessKind");
2406 }
2407