ThreadSafety.cpp source code [clang_source_code/lib/Analysis/ThreadSafety.cpp]

1	//===- ThreadSafety.cpp ---------------------------------------------------===//
2	//
3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4	// See https://llvm.org/LICENSE.txt for license information.
5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6	//
7	//===----------------------------------------------------------------------===//
8	//
9	// A intra-procedural analysis for thread safety (e.g. deadlocks and race
10	// conditions), based off of an annotation system.
11	//
12	// See http://clang.llvm.org/docs/ThreadSafetyAnalysis.html
13	// for more information.
14	//
15	//===----------------------------------------------------------------------===//
16
17	#include "clang/Analysis/Analyses/ThreadSafety.h"
18	#include "clang/AST/Attr.h"
19	#include "clang/AST/Decl.h"
20	#include "clang/AST/DeclCXX.h"
21	#include "clang/AST/DeclGroup.h"
22	#include "clang/AST/Expr.h"
23	#include "clang/AST/ExprCXX.h"
24	#include "clang/AST/OperationKinds.h"
25	#include "clang/AST/Stmt.h"
26	#include "clang/AST/StmtVisitor.h"
27	#include "clang/AST/Type.h"
28	#include "clang/Analysis/Analyses/PostOrderCFGView.h"
29	#include "clang/Analysis/Analyses/ThreadSafetyCommon.h"
30	#include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
31	#include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
32	#include "clang/Analysis/Analyses/ThreadSafetyUtil.h"
33	#include "clang/Analysis/AnalysisDeclContext.h"
34	#include "clang/Analysis/CFG.h"
35	#include "clang/Basic/Builtins.h"
36	#include "clang/Basic/LLVM.h"
37	#include "clang/Basic/OperatorKinds.h"
38	#include "clang/Basic/SourceLocation.h"
39	#include "clang/Basic/Specifiers.h"
40	#include "llvm/ADT/ArrayRef.h"
41	#include "llvm/ADT/DenseMap.h"
42	#include "llvm/ADT/ImmutableMap.h"
43	#include "llvm/ADT/Optional.h"
44	#include "llvm/ADT/PointerIntPair.h"
45	#include "llvm/ADT/STLExtras.h"
46	#include "llvm/ADT/SmallVector.h"
47	#include "llvm/ADT/StringRef.h"
48	#include "llvm/Support/Allocator.h"
49	#include "llvm/Support/Casting.h"
50	#include "llvm/Support/ErrorHandling.h"
51	#include "llvm/Support/raw_ostream.h"
52	#include <algorithm>
53	#include <cassert>
54	#include <functional>
55	#include <iterator>
56	#include <memory>
57	#include <string>
58	#include <type_traits>
59	#include <utility>
60	#include <vector>
61
62	using namespace clang;
63	using namespace threadSafety;
64
65	// Key method definition
66	ThreadSafetyHandler::~ThreadSafetyHandler() = default;
67
68	/// Issue a warning about an invalid lock expression
69	static void warnInvalidLock(ThreadSafetyHandler &Handler,
70	const Expr MutexExp, const NamedDecl D,
71	const Expr *DeclExp, StringRef Kind) {
72	SourceLocation Loc;
73	if (DeclExp)
74	Loc = DeclExp->getExprLoc();
75
76	// FIXME: add a note about the attribute location in MutexExp or D
77	if (Loc.isValid())
78	Handler.handleInvalidLockExp(Kind, Loc);
79	}
80
81	namespace {
82
83	/// A set of CapabilityExpr objects, which are compiled from thread safety
84	/// attributes on a function.
85	class CapExprSet : public SmallVector<CapabilityExpr, 4> {
86	public:
87	/// Push M onto list, but discard duplicates.
88	void push_back_nodup(const CapabilityExpr &CapE) {
89	iterator It = std::find_if(begin(), end(),
90	[=](const CapabilityExpr &CapE2) {
91	return CapE.equals(CapE2);
92	});
93	if (It == end())
94	push_back(CapE);
95	}
96	};
97
98	class FactManager;
99	class FactSet;
100
101	/// This is a helper class that stores a fact that is known at a
102	/// particular point in program execution. Currently, a fact is a capability,
103	/// along with additional information, such as where it was acquired, whether
104	/// it is exclusive or shared, etc.
105	///
106	/// FIXME: this analysis does not currently support re-entrant locking.
107	class FactEntry : public CapabilityExpr {
108	private:
109	/// Exclusive or shared.
110	LockKind LKind;
111
112	/// Where it was acquired.
113	SourceLocation AcquireLoc;
114
115	/// True if the lock was asserted.
116	bool Asserted;
117
118	/// True if the lock was declared.
119	bool Declared;
120
121	public:
122	FactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
123	bool Asrt, bool Declrd = false)
124	: CapabilityExpr(CE), LKind(LK), AcquireLoc(Loc), Asserted(Asrt),
125	Declared(Declrd) {}
126	virtual ~FactEntry() = default;
127
128	LockKind kind() const { return LKind; }
129	SourceLocation loc() const { return AcquireLoc; }
130	bool asserted() const { return Asserted; }
131	bool declared() const { return Declared; }
132
133	void setDeclared(bool D) { Declared = D; }
134
135	virtual void
136	handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
137	SourceLocation JoinLoc, LockErrorKind LEK,
138	ThreadSafetyHandler &Handler) const = 0;
139	virtual void handleLock(FactSet &FSet, FactManager &FactMan,
140	const FactEntry &entry, ThreadSafetyHandler &Handler,
141	StringRef DiagKind) const = 0;
142	virtual void handleUnlock(FactSet &FSet, FactManager &FactMan,
143	const CapabilityExpr &Cp, SourceLocation UnlockLoc,
144	bool FullyRemove, ThreadSafetyHandler &Handler,
145	StringRef DiagKind) const = 0;
146
147	// Return true if LKind >= LK, where exclusive > shared
148	bool isAtLeast(LockKind LK) const {
149	return (LKind == LK_Exclusive) \|\| (LK == LK_Shared);
150	}
151	};
152
153	using FactID = unsigned short;
154
155	/// FactManager manages the memory for all facts that are created during
156	/// the analysis of a single routine.
157	class FactManager {
158	private:
159	std::vector<std::unique_ptr<const FactEntry>> Facts;
160
161	public:
162	FactID newFact(std::unique_ptr<FactEntry> Entry) {
163	Facts.push_back(std::move(Entry));
164	return static_cast<unsigned short>(Facts.size() - 1);
165	}
166
167	const FactEntry &operator[](FactID F) const { return *Facts[F]; }
168	};
169
170	/// A FactSet is the set of facts that are known to be true at a
171	/// particular program point. FactSets must be small, because they are
172	/// frequently copied, and are thus implemented as a set of indices into a
173	/// table maintained by a FactManager. A typical FactSet only holds 1 or 2
174	/// locks, so we can get away with doing a linear search for lookup. Note
175	/// that a hashtable or map is inappropriate in this case, because lookups
176	/// may involve partial pattern matches, rather than exact matches.
177	class FactSet {
178	private:
179	using FactVec = SmallVector<FactID, 4>;
180
181	FactVec FactIDs;
182
183	public:
184	using iterator = FactVec::iterator;
185	using const_iterator = FactVec::const_iterator;
186
187	iterator begin() { return FactIDs.begin(); }
188	const_iterator begin() const { return FactIDs.begin(); }
189
190	iterator end() { return FactIDs.end(); }
191	const_iterator end() const { return FactIDs.end(); }
192
193	bool isEmpty() const { return FactIDs.size() == 0; }
194
195	// Return true if the set contains only negative facts
196	bool isEmpty(FactManager &FactMan) const {
197	for (const auto FID : *this) {
198	if (!FactMan[FID].negative())
199	return false;
200	}
201	return true;
202	}
203
204	void addLockByID(FactID ID) { FactIDs.push_back(ID); }
205
206	FactID addLock(FactManager &FM, std::unique_ptr<FactEntry> Entry) {
207	FactID F = FM.newFact(std::move(Entry));
208	FactIDs.push_back(F);
209	return F;
210	}
211
212	bool removeLock(FactManager& FM, const CapabilityExpr &CapE) {
213	unsigned n = FactIDs.size();
214	if (n == 0)
215	return false;
216
217	for (unsigned i = 0; i < n-1; ++i) {
218	if (FM[FactIDs[i]].matches(CapE)) {
219	FactIDs[i] = FactIDs[n-1];
220	FactIDs.pop_back();
221	return true;
222	}
223	}
224	if (FM[FactIDs[n-1]].matches(CapE)) {
225	FactIDs.pop_back();
226	return true;
227	}
228	return false;
229	}
230
231	iterator findLockIter(FactManager &FM, const CapabilityExpr &CapE) {
232	return std::find_if(begin(), end(), [&](FactID ID) {
233	return FM[ID].matches(CapE);
234	});
235	}
236
237	const FactEntry *findLock(FactManager &FM, const CapabilityExpr &CapE) const {
238	auto I = std::find_if(begin(), end(), [&](FactID ID) {
239	return FM[ID].matches(CapE);
240	});
241	return I != end() ? &FM[*I] : nullptr;
242	}
243
244	const FactEntry *findLockUniv(FactManager &FM,
245	const CapabilityExpr &CapE) const {
246	auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
247	return FM[ID].matchesUniv(CapE);
248	});
249	return I != end() ? &FM[*I] : nullptr;
250	}
251
252	const FactEntry *findPartialMatch(FactManager &FM,
253	const CapabilityExpr &CapE) const {
254	auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
255	return FM[ID].partiallyMatches(CapE);
256	});
257	return I != end() ? &FM[*I] : nullptr;
258	}
259
260	bool containsMutexDecl(FactManager &FM, const ValueDecl* Vd) const {
261	auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
262	return FM[ID].valueDecl() == Vd;
263	});
264	return I != end();
265	}
266	};
267
268	class ThreadSafetyAnalyzer;
269
270	} // namespace
271
272	namespace clang {
273	namespace threadSafety {
274
275	class BeforeSet {
276	private:
277	using BeforeVect = SmallVector<const ValueDecl *, 4>;
278
279	struct BeforeInfo {
280	BeforeVect Vect;
281	int Visited = 0;
282
283	BeforeInfo() = default;
284	BeforeInfo(BeforeInfo &&) = default;
285	};
286
287	using BeforeMap =
288	llvm::DenseMap<const ValueDecl *, std::unique_ptr<BeforeInfo>>;
289	using CycleMap = llvm::DenseMap<const ValueDecl *, bool>;
290
291	public:
292	BeforeSet() = default;
293
294	BeforeInfo* insertAttrExprs(const ValueDecl* Vd,
295	ThreadSafetyAnalyzer& Analyzer);
296
297	BeforeInfo getBeforeInfoForDecl(const ValueDecl Vd,
298	ThreadSafetyAnalyzer &Analyzer);
299
300	void checkBeforeAfter(const ValueDecl* Vd,
301	const FactSet& FSet,
302	ThreadSafetyAnalyzer& Analyzer,
303	SourceLocation Loc, StringRef CapKind);
304
305	private:
306	BeforeMap BMap;
307	CycleMap CycMap;
308	};
309
310	} // namespace threadSafety
311	} // namespace clang
312
313	namespace {
314
315	class LocalVariableMap;
316
317	using LocalVarContext = llvm::ImmutableMap<const NamedDecl *, unsigned>;
318
319	/// A side (entry or exit) of a CFG node.
320	enum CFGBlockSide { CBS_Entry, CBS_Exit };
321
322	/// CFGBlockInfo is a struct which contains all the information that is
323	/// maintained for each block in the CFG. See LocalVariableMap for more
324	/// information about the contexts.
325	struct CFGBlockInfo {
326	// Lockset held at entry to block
327	FactSet EntrySet;
328
329	// Lockset held at exit from block
330	FactSet ExitSet;
331
332	// Context held at entry to block
333	LocalVarContext EntryContext;
334
335	// Context held at exit from block
336	LocalVarContext ExitContext;
337
338	// Location of first statement in block
339	SourceLocation EntryLoc;
340
341	// Location of last statement in block.
342	SourceLocation ExitLoc;
343
344	// Used to replay contexts later
345	unsigned EntryIndex;
346
347	// Is this block reachable?
348	bool Reachable = false;
349
350	const FactSet &getSet(CFGBlockSide Side) const {
351	return Side == CBS_Entry ? EntrySet : ExitSet;
352	}
353
354	SourceLocation getLocation(CFGBlockSide Side) const {
355	return Side == CBS_Entry ? EntryLoc : ExitLoc;
356	}
357
358	private:
359	CFGBlockInfo(LocalVarContext EmptyCtx)
360	: EntryContext(EmptyCtx), ExitContext(EmptyCtx) {}
361
362	public:
363	static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
364	};
365
366	// A LocalVariableMap maintains a map from local variables to their currently
367	// valid definitions. It provides SSA-like functionality when traversing the
368	// CFG. Like SSA, each definition or assignment to a variable is assigned a
369	// unique name (an integer), which acts as the SSA name for that definition.
370	// The total set of names is shared among all CFG basic blocks.
371	// Unlike SSA, we do not rewrite expressions to replace local variables declrefs
372	// with their SSA-names. Instead, we compute a Context for each point in the
373	// code, which maps local variables to the appropriate SSA-name. This map
374	// changes with each assignment.
375	//
376	// The map is computed in a single pass over the CFG. Subsequent analyses can
377	// then query the map to find the appropriate Context for a statement, and use
378	// that Context to look up the definitions of variables.
379	class LocalVariableMap {
380	public:
381	using Context = LocalVarContext;
382
383	/// A VarDefinition consists of an expression, representing the value of the
384	/// variable, along with the context in which that expression should be
385	/// interpreted. A reference VarDefinition does not itself contain this
386	/// information, but instead contains a pointer to a previous VarDefinition.
387	struct VarDefinition {
388	public:
389	friend class LocalVariableMap;
390
391	// The original declaration for this variable.
392	const NamedDecl *Dec;
393
394	// The expression for this variable, OR
395	const Expr *Exp = nullptr;
396
397	// Reference to another VarDefinition
398	unsigned Ref = 0;
399
400	// The map with which Exp should be interpreted.
401	Context Ctx;
402
403	bool isReference() { return !Exp; }
404
405	private:
406	// Create ordinary variable definition
407	VarDefinition(const NamedDecl D, const Expr E, Context C)
408	: Dec(D), Exp(E), Ctx(C) {}
409
410	// Create reference to previous definition
411	VarDefinition(const NamedDecl *D, unsigned R, Context C)
412	: Dec(D), Ref(R), Ctx(C) {}
413	};
414
415	private:
416	Context::Factory ContextFactory;
417	std::vector<VarDefinition> VarDefinitions;
418	std::vector<unsigned> CtxIndices;
419	std::vector<std::pair<const Stmt *, Context>> SavedContexts;
420
421	public:
422	LocalVariableMap() {
423	// index 0 is a placeholder for undefined variables (aka phi-nodes).
424	VarDefinitions.push_back(VarDefinition(nullptr, 0u, getEmptyContext()));
425	}
426
427	/// Look up a definition, within the given context.
428	const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
429	const unsigned *i = Ctx.lookup(D);
430	if (!i)
431	return nullptr;
432	assert(*i < VarDefinitions.size());
433	return &VarDefinitions[*i];
434	}
435
436	/// Look up the definition for D within the given context. Returns
437	/// NULL if the expression is not statically known. If successful, also
438	/// modifies Ctx to hold the context of the return Expr.
439	const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
440	const unsigned *P = Ctx.lookup(D);
441	if (!P)
442	return nullptr;
443
444	unsigned i = *P;
445	while (i > 0) {
446	if (VarDefinitions[i].Exp) {
447	Ctx = VarDefinitions[i].Ctx;
448	return VarDefinitions[i].Exp;
449	}
450	i = VarDefinitions[i].Ref;
451	}
452	return nullptr;
453	}
454
455	Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
456
457	/// Return the next context after processing S. This function is used by
458	/// clients of the class to get the appropriate context when traversing the
459	/// CFG. It must be called for every assignment or DeclStmt.
460	Context getNextContext(unsigned &CtxIndex, const Stmt *S, Context C) {
461	if (SavedContexts[CtxIndex+1].first == S) {
462	CtxIndex++;
463	Context Result = SavedContexts[CtxIndex].second;
464	return Result;
465	}
466	return C;
467	}
468
469	void dumpVarDefinitionName(unsigned i) {
470	if (i == 0) {
471	llvm::errs() << "Undefined";
472	return;
473	}
474	const NamedDecl *Dec = VarDefinitions[i].Dec;
475	if (!Dec) {
476	llvm::errs() << "<<NULL>>";
477	return;
478	}
479	Dec->printName(llvm::errs());
480	llvm::errs() << "." << i << " " << ((const void*) Dec);
481	}
482
483	/// Dumps an ASCII representation of the variable map to llvm::errs()
484	void dump() {
485	for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
486	const Expr *Exp = VarDefinitions[i].Exp;
487	unsigned Ref = VarDefinitions[i].Ref;
488
489	dumpVarDefinitionName(i);
490	llvm::errs() << " = ";
491	if (Exp) Exp->dump();
492	else {
493	dumpVarDefinitionName(Ref);
494	llvm::errs() << "\n";
495	}
496	}
497	}
498
499	/// Dumps an ASCII representation of a Context to llvm::errs()
500	void dumpContext(Context C) {
501	for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
502	const NamedDecl *D = I.getKey();
503	D->printName(llvm::errs());
504	const unsigned *i = C.lookup(D);
505	llvm::errs() << " -> ";
506	dumpVarDefinitionName(*i);
507	llvm::errs() << "\n";
508	}
509	}
510
511	/// Builds the variable map.
512	void traverseCFG(CFG CFGraph, const PostOrderCFGView SortedGraph,
513	std::vector<CFGBlockInfo> &BlockInfo);
514
515	protected:
516	friend class VarMapBuilder;
517
518	// Get the current context index
519	unsigned getContextIndex() { return SavedContexts.size()-1; }
520
521	// Save the current context for later replay
522	void saveContext(const Stmt *S, Context C) {
523	SavedContexts.push_back(std::make_pair(S, C));
524	}
525
526	// Adds a new definition to the given context, and returns a new context.
527	// This method should be called when declaring a new variable.
528	Context addDefinition(const NamedDecl D, const Expr Exp, Context Ctx) {
529	assert(!Ctx.contains(D));
530	unsigned newID = VarDefinitions.size();
531	Context NewCtx = ContextFactory.add(Ctx, D, newID);
532	VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
533	return NewCtx;
534	}
535
536	// Add a new reference to an existing definition.
537	Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
538	unsigned newID = VarDefinitions.size();
539	Context NewCtx = ContextFactory.add(Ctx, D, newID);
540	VarDefinitions.push_back(VarDefinition(D, i, Ctx));
541	return NewCtx;
542	}
543
544	// Updates a definition only if that definition is already in the map.
545	// This method should be called when assigning to an existing variable.
546	Context updateDefinition(const NamedDecl D, Expr Exp, Context Ctx) {
547	if (Ctx.contains(D)) {
548	unsigned newID = VarDefinitions.size();
549	Context NewCtx = ContextFactory.remove(Ctx, D);
550	NewCtx = ContextFactory.add(NewCtx, D, newID);
551	VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
552	return NewCtx;
553	}
554	return Ctx;
555	}
556
557	// Removes a definition from the context, but keeps the variable name
558	// as a valid variable. The index 0 is a placeholder for cleared definitions.
559	Context clearDefinition(const NamedDecl *D, Context Ctx) {
560	Context NewCtx = Ctx;
561	if (NewCtx.contains(D)) {
562	NewCtx = ContextFactory.remove(NewCtx, D);
563	NewCtx = ContextFactory.add(NewCtx, D, 0);
564	}
565	return NewCtx;
566	}
567
568	// Remove a definition entirely frmo the context.
569	Context removeDefinition(const NamedDecl *D, Context Ctx) {
570	Context NewCtx = Ctx;
571	if (NewCtx.contains(D)) {
572	NewCtx = ContextFactory.remove(NewCtx, D);
573	}
574	return NewCtx;
575	}
576
577	Context intersectContexts(Context C1, Context C2);
578	Context createReferenceContext(Context C);
579	void intersectBackEdge(Context C1, Context C2);
580	};
581
582	} // namespace
583
584	// This has to be defined after LocalVariableMap.
585	CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
586	return CFGBlockInfo(M.getEmptyContext());
587	}
588
589	namespace {
590
591	/// Visitor which builds a LocalVariableMap
592	class VarMapBuilder : public ConstStmtVisitor<VarMapBuilder> {
593	public:
594	LocalVariableMap* VMap;
595	LocalVariableMap::Context Ctx;
596
597	VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
598	: VMap(VM), Ctx(C) {}
599
600	void VisitDeclStmt(const DeclStmt *S);
601	void VisitBinaryOperator(const BinaryOperator *BO);
602	};
603
604	} // namespace
605
606	// Add new local variables to the variable map
607	void VarMapBuilder::VisitDeclStmt(const DeclStmt *S) {
608	bool modifiedCtx = false;
609	const DeclGroupRef DGrp = S->getDeclGroup();
610	for (const auto *D : DGrp) {
611	if (const auto *VD = dyn_cast_or_null<VarDecl>(D)) {
612	const Expr *E = VD->getInit();
613
614	// Add local variables with trivial type to the variable map
615	QualType T = VD->getType();
616	if (T.isTrivialType(VD->getASTContext())) {
617	Ctx = VMap->addDefinition(VD, E, Ctx);
618	modifiedCtx = true;
619	}
620	}
621	}
622	if (modifiedCtx)
623	VMap->saveContext(S, Ctx);
624	}
625
626	// Update local variable definitions in variable map
627	void VarMapBuilder::VisitBinaryOperator(const BinaryOperator *BO) {
628	if (!BO->isAssignmentOp())
629	return;
630
631	Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
632
633	// Update the variable map and current context.
634	if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
635	const ValueDecl *VDec = DRE->getDecl();
636	if (Ctx.lookup(VDec)) {
637	if (BO->getOpcode() == BO_Assign)
638	Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
639	else
640	// FIXME -- handle compound assignment operators
641	Ctx = VMap->clearDefinition(VDec, Ctx);
642	VMap->saveContext(BO, Ctx);
643	}
644	}
645	}
646
647	// Computes the intersection of two contexts. The intersection is the
648	// set of variables which have the same definition in both contexts;
649	// variables with different definitions are discarded.
650	LocalVariableMap::Context
651	LocalVariableMap::intersectContexts(Context C1, Context C2) {
652	Context Result = C1;
653	for (const auto &P : C1) {
654	const NamedDecl *Dec = P.first;
655	const unsigned *i2 = C2.lookup(Dec);
656	if (!i2) // variable doesn't exist on second path
657	Result = removeDefinition(Dec, Result);
658	else if (*i2 != P.second) // variable exists, but has different definition
659	Result = clearDefinition(Dec, Result);
660	}
661	return Result;
662	}
663
664	// For every variable in C, create a new variable that refers to the
665	// definition in C. Return a new context that contains these new variables.
666	// (We use this for a naive implementation of SSA on loop back-edges.)
667	LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
668	Context Result = getEmptyContext();
669	for (const auto &P : C)
670	Result = addReference(P.first, P.second, Result);
671	return Result;
672	}
673
674	// This routine also takes the intersection of C1 and C2, but it does so by
675	// altering the VarDefinitions. C1 must be the result of an earlier call to
676	// createReferenceContext.
677	void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
678	for (const auto &P : C1) {
679	unsigned i1 = P.second;
680	VarDefinition *VDef = &VarDefinitions[i1];
681	isReference()", "/home/seafit/code_projects/clang_source/clang/lib/Analysis/ThreadSafety.cpp", 681, __PRETTY_FUNCTION__))" file_link="../../../include/assert.h.html#88" macro="true">assert(VDef->isReference());
682
683	const unsigned *i2 = C2.lookup(P.first);
684	if (!i2 \|\| (*i2 != i1))
685	VDef->Ref = 0; // Mark this variable as undefined
686	}
687	}
688
689	// Traverse the CFG in topological order, so all predecessors of a block
690	// (excluding back-edges) are visited before the block itself. At
691	// each point in the code, we calculate a Context, which holds the set of
692	// variable definitions which are visible at that point in execution.
693	// Visible variables are mapped to their definitions using an array that
694	// contains all definitions.
695	//
696	// At join points in the CFG, the set is computed as the intersection of
697	// the incoming sets along each edge, E.g.
698	//
699	// { Context \| VarDefinitions }
700	// int x = 0; { x -> x1 \| x1 = 0 }
701	// int y = 0; { x -> x1, y -> y1 \| y1 = 0, x1 = 0 }
702	// if (b) x = 1; { x -> x2, y -> y1 \| x2 = 1, y1 = 0, ... }
703	// else x = 2; { x -> x3, y -> y1 \| x3 = 2, x2 = 1, ... }
704	// ... { y -> y1 (x is unknown) \| x3 = 2, x2 = 1, ... }
705	//
706	// This is essentially a simpler and more naive version of the standard SSA
707	// algorithm. Those definitions that remain in the intersection are from blocks
708	// that strictly dominate the current block. We do not bother to insert proper
709	// phi nodes, because they are not used in our analysis; instead, wherever
710	// a phi node would be required, we simply remove that definition from the
711	// context (E.g. x above).
712	//
713	// The initial traversal does not capture back-edges, so those need to be
714	// handled on a separate pass. Whenever the first pass encounters an
715	// incoming back edge, it duplicates the context, creating new definitions
716	// that refer back to the originals. (These correspond to places where SSA
717	// might have to insert a phi node.) On the second pass, these definitions are
718	// set to NULL if the variable has changed on the back-edge (i.e. a phi
719	// node was actually required.) E.g.
720	//
721	// { Context \| VarDefinitions }
722	// int x = 0, y = 0; { x -> x1, y -> y1 \| y1 = 0, x1 = 0 }
723	// while (b) { x -> x2, y -> y1 \| [1st:] x2=x1; [2nd:] x2=NULL; }
724	// x = x+1; { x -> x3, y -> y1 \| x3 = x2 + 1, ... }
725	// ... { y -> y1 \| x3 = 2, x2 = 1, ... }
726	void LocalVariableMap::traverseCFG(CFG *CFGraph,
727	const PostOrderCFGView *SortedGraph,
728	std::vector<CFGBlockInfo> &BlockInfo) {
729	PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
730
731	CtxIndices.resize(CFGraph->getNumBlockIDs());
732
733	for (const auto CurrBlock : SortedGraph) {
734	unsigned CurrBlockID = CurrBlock->getBlockID();
735	CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
736
737	VisitedBlocks.insert(CurrBlock);
738
739	// Calculate the entry context for the current block
740	bool HasBackEdges = false;
741	bool CtxInit = true;
742	for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
743	PE = CurrBlock->pred_end(); PI != PE; ++PI) {
744	// if *PI -> CurrBlock is a back edge, so skip it
745	if (PI == nullptr \|\| !VisitedBlocks.alreadySet(PI)) {
746	HasBackEdges = true;
747	continue;
748	}
749
750	unsigned PrevBlockID = (*PI)->getBlockID();
751	CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
752
753	if (CtxInit) {
754	CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
755	CtxInit = false;
756	}
757	else {
758	CurrBlockInfo->EntryContext =
759	intersectContexts(CurrBlockInfo->EntryContext,
760	PrevBlockInfo->ExitContext);
761	}
762	}
763
764	// Duplicate the context if we have back-edges, so we can call
765	// intersectBackEdges later.
766	if (HasBackEdges)
767	CurrBlockInfo->EntryContext =
768	createReferenceContext(CurrBlockInfo->EntryContext);
769
770	// Create a starting context index for the current block
771	saveContext(nullptr, CurrBlockInfo->EntryContext);
772	CurrBlockInfo->EntryIndex = getContextIndex();
773
774	// Visit all the statements in the basic block.
775	VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
776	for (const auto &BI : *CurrBlock) {
777	switch (BI.getKind()) {
778	case CFGElement::Statement: {
779	CFGStmt CS = BI.castAs<CFGStmt>();
780	VMapBuilder.Visit(CS.getStmt());
781	break;
782	}
783	default:
784	break;
785	}
786	}
787	CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
788
789	// Mark variables on back edges as "unknown" if they've been changed.
790	for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
791	SE = CurrBlock->succ_end(); SI != SE; ++SI) {
792	// if CurrBlock -> SI is not* a back edge
793	if (SI == nullptr \|\| !VisitedBlocks.alreadySet(SI))
794	continue;
795
796	CFGBlock FirstLoopBlock = SI;
797	Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
798	Context LoopEnd = CurrBlockInfo->ExitContext;
799	intersectBackEdge(LoopBegin, LoopEnd);
800	}
801	}
802
803	// Put an extra entry at the end of the indexed context array
804	unsigned exitID = CFGraph->getExit().getBlockID();
805	saveContext(nullptr, BlockInfo[exitID].ExitContext);
806	}
807
808	/// Find the appropriate source locations to use when producing diagnostics for
809	/// each block in the CFG.
810	static void findBlockLocations(CFG *CFGraph,
811	const PostOrderCFGView *SortedGraph,
812	std::vector<CFGBlockInfo> &BlockInfo) {
813	for (const auto CurrBlock : SortedGraph) {
814	CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
815
816	// Find the source location of the last statement in the block, if the
817	// block is not empty.
818	if (const Stmt *S = CurrBlock->getTerminator()) {
819	CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getBeginLoc();
820	} else {
821	for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
822	BE = CurrBlock->rend(); BI != BE; ++BI) {
823	// FIXME: Handle other CFGElement kinds.
824	if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
825	CurrBlockInfo->ExitLoc = CS->getStmt()->getBeginLoc();
826	break;
827	}
828	}
829	}
830
831	if (CurrBlockInfo->ExitLoc.isValid()) {
832	// This block contains at least one statement. Find the source location
833	// of the first statement in the block.
834	for (const auto &BI : *CurrBlock) {
835	// FIXME: Handle other CFGElement kinds.
836	if (Optional<CFGStmt> CS = BI.getAs<CFGStmt>()) {
837	CurrBlockInfo->EntryLoc = CS->getStmt()->getBeginLoc();
838	break;
839	}
840	}
841	} else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
842	CurrBlock != &CFGraph->getExit()) {
843	// The block is empty, and has a single predecessor. Use its exit
844	// location.
845	CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
846	BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
847	}
848	}
849	}
850
851	namespace {
852
853	class LockableFactEntry : public FactEntry {
854	private:
855	/// managed by ScopedLockable object
856	bool Managed;
857
858	public:
859	LockableFactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
860	bool Mng = false, bool Asrt = false)
861	: FactEntry(CE, LK, Loc, Asrt), Managed(Mng) {}
862
863	void
864	handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
865	SourceLocation JoinLoc, LockErrorKind LEK,
866	ThreadSafetyHandler &Handler) const override {
867	if (!Managed && !asserted() && !negative() && !isUniversal()) {
868	Handler.handleMutexHeldEndOfScope("mutex", toString(), loc(), JoinLoc,
869	LEK);
870	}
871	}
872
873	void handleLock(FactSet &FSet, FactManager &FactMan, const FactEntry &entry,
874	ThreadSafetyHandler &Handler,
875	StringRef DiagKind) const override {
876	Handler.handleDoubleLock(DiagKind, entry.toString(), loc(), entry.loc());
877	}
878
879	void handleUnlock(FactSet &FSet, FactManager &FactMan,
880	const CapabilityExpr &Cp, SourceLocation UnlockLoc,
881	bool FullyRemove, ThreadSafetyHandler &Handler,
882	StringRef DiagKind) const override {
883	FSet.removeLock(FactMan, Cp);
884	if (!Cp.negative()) {
885	FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
886	!Cp, LK_Exclusive, UnlockLoc));
887	}
888	}
889	};
890
891	class ScopedLockableFactEntry : public FactEntry {
892	private:
893	enum UnderlyingCapabilityKind {
894	UCK_Acquired, ///< Any kind of acquired capability.
895	UCK_ReleasedShared, ///< Shared capability that was released.
896	UCK_ReleasedExclusive, ///< Exclusive capability that was released.
897	};
898
899	using UnderlyingCapability =
900	llvm::PointerIntPair<const til::SExpr *, 2, UnderlyingCapabilityKind>;
901
902	SmallVector<UnderlyingCapability, 4> UnderlyingMutexes;
903
904	public:
905	ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc)
906	: FactEntry(CE, LK_Exclusive, Loc, false) {}
907
908	void addExclusiveLock(const CapabilityExpr &M) {
909	UnderlyingMutexes.emplace_back(M.sexpr(), UCK_Acquired);
910	}
911
912	void addSharedLock(const CapabilityExpr &M) {
913	UnderlyingMutexes.emplace_back(M.sexpr(), UCK_Acquired);
914	}
915
916	void addExclusiveUnlock(const CapabilityExpr &M) {
917	UnderlyingMutexes.emplace_back(M.sexpr(), UCK_ReleasedExclusive);
918	}
919
920	void addSharedUnlock(const CapabilityExpr &M) {
921	UnderlyingMutexes.emplace_back(M.sexpr(), UCK_ReleasedShared);
922	}
923
924	void
925	handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
926	SourceLocation JoinLoc, LockErrorKind LEK,
927	ThreadSafetyHandler &Handler) const override {
928	for (const auto &UnderlyingMutex : UnderlyingMutexes) {
929	const auto *Entry = FSet.findLock(
930	FactMan, CapabilityExpr(UnderlyingMutex.getPointer(), false));
931	if ((UnderlyingMutex.getInt() == UCK_Acquired && Entry) \|\|
932	(UnderlyingMutex.getInt() != UCK_Acquired && !Entry)) {
933	// If this scoped lock manages another mutex, and if the underlying
934	// mutex is still/not held, then warn about the underlying mutex.
935	Handler.handleMutexHeldEndOfScope(
936	"mutex", sx::toString(UnderlyingMutex.getPointer()), loc(), JoinLoc,
937	LEK);
938	}
939	}
940	}
941
942	void handleLock(FactSet &FSet, FactManager &FactMan, const FactEntry &entry,
943	ThreadSafetyHandler &Handler,
944	StringRef DiagKind) const override {
945	for (const auto &UnderlyingMutex : UnderlyingMutexes) {
946	CapabilityExpr UnderCp(UnderlyingMutex.getPointer(), false);
947
948	if (UnderlyingMutex.getInt() == UCK_Acquired)
949	lock(FSet, FactMan, UnderCp, entry.kind(), entry.loc(), &Handler,
950	DiagKind);
951	else
952	unlock(FSet, FactMan, UnderCp, entry.loc(), &Handler, DiagKind);
953	}
954	}
955
956	void handleUnlock(FactSet &FSet, FactManager &FactMan,
957	const CapabilityExpr &Cp, SourceLocation UnlockLoc,
958	bool FullyRemove, ThreadSafetyHandler &Handler,
959	StringRef DiagKind) const override {
960	(0) . __assert_fail ("!Cp.negative() && \"Managing object cannot be negative.\"", "/home/seafit/code_projects/clang_source/clang/lib/Analysis/ThreadSafety.cpp", 960, __PRETTY_FUNCTION__))" file_link="../../../include/assert.h.html#88" macro="true">assert(!Cp.negative() && "Managing object cannot be negative.");
961	for (const auto &UnderlyingMutex : UnderlyingMutexes) {
962	CapabilityExpr UnderCp(UnderlyingMutex.getPointer(), false);
963
964	// Remove/lock the underlying mutex if it exists/is still unlocked; warn
965	// on double unlocking/locking if we're not destroying the scoped object.
966	ThreadSafetyHandler *TSHandler = FullyRemove ? nullptr : &Handler;
967	if (UnderlyingMutex.getInt() == UCK_Acquired) {
968	unlock(FSet, FactMan, UnderCp, UnlockLoc, TSHandler, DiagKind);
969	} else {
970	LockKind kind = UnderlyingMutex.getInt() == UCK_ReleasedShared
971	? LK_Shared
972	: LK_Exclusive;
973	lock(FSet, FactMan, UnderCp, kind, UnlockLoc, TSHandler, DiagKind);
974	}
975	}
976	if (FullyRemove)
977	FSet.removeLock(FactMan, Cp);
978	}
979
980	private:
981	void lock(FactSet &FSet, FactManager &FactMan, const CapabilityExpr &Cp,
982	LockKind kind, SourceLocation loc, ThreadSafetyHandler *Handler,
983	StringRef DiagKind) const {
984	if (const FactEntry *Fact = FSet.findLock(FactMan, Cp)) {
985	if (Handler)
986	Handler->handleDoubleLock(DiagKind, Cp.toString(), Fact->loc(), loc);
987	} else {
988	FSet.removeLock(FactMan, !Cp);
989	FSet.addLock(FactMan,
990	llvm::make_unique<LockableFactEntry>(Cp, kind, loc));
991	}
992	}
993
994	void unlock(FactSet &FSet, FactManager &FactMan, const CapabilityExpr &Cp,
995	SourceLocation loc, ThreadSafetyHandler *Handler,
996	StringRef DiagKind) const {
997	if (FSet.findLock(FactMan, Cp)) {
998	FSet.removeLock(FactMan, Cp);
999	FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
1000	!Cp, LK_Exclusive, loc));
1001	} else if (Handler) {
1002	Handler->handleUnmatchedUnlock(DiagKind, Cp.toString(), loc);
1003	}
1004	}
1005	};
1006
1007	/// Class which implements the core thread safety analysis routines.
1008	class ThreadSafetyAnalyzer {
1009	friend class BuildLockset;
1010	friend class threadSafety::BeforeSet;
1011
1012	llvm::BumpPtrAllocator Bpa;
1013	threadSafety::til::MemRegionRef Arena;
1014	threadSafety::SExprBuilder SxBuilder;
1015
1016	ThreadSafetyHandler &Handler;
1017	const CXXMethodDecl *CurrentMethod;
1018	LocalVariableMap LocalVarMap;
1019	FactManager FactMan;
1020	std::vector<CFGBlockInfo> BlockInfo;
1021
1022	BeforeSet *GlobalBeforeSet;
1023
1024	public:
1025	ThreadSafetyAnalyzer(ThreadSafetyHandler &H, BeforeSet* Bset)
1026	: Arena(&Bpa), SxBuilder(Arena), Handler(H), GlobalBeforeSet(Bset) {}
1027
1028	bool inCurrentScope(const CapabilityExpr &CapE);
1029
1030	void addLock(FactSet &FSet, std::unique_ptr<FactEntry> Entry,
1031	StringRef DiagKind, bool ReqAttr = false);
1032	void removeLock(FactSet &FSet, const CapabilityExpr &CapE,
1033	SourceLocation UnlockLoc, bool FullyRemove, LockKind Kind,
1034	StringRef DiagKind);
1035
1036	template <typename AttrType>
1037	void getMutexIDs(CapExprSet &Mtxs, AttrType Attr, const Expr Exp,
1038	const NamedDecl D, VarDecl SelfDecl = nullptr);
1039
1040	template <class AttrType>
1041	void getMutexIDs(CapExprSet &Mtxs, AttrType Attr, const Expr Exp,
1042	const NamedDecl *D,
1043	const CFGBlock PredBlock, const CFGBlock CurrBlock,
1044	Expr *BrE, bool Neg);
1045
1046	const CallExpr* getTrylockCallExpr(const Stmt *Cond, LocalVarContext C,
1047	bool &Negate);
1048
1049	void getEdgeLockset(FactSet &Result, const FactSet &ExitSet,
1050	const CFGBlock* PredBlock,
1051	const CFGBlock *CurrBlock);
1052
1053	void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
1054	SourceLocation JoinLoc,
1055	LockErrorKind LEK1, LockErrorKind LEK2,
1056	bool Modify=true);
1057
1058	void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
1059	SourceLocation JoinLoc, LockErrorKind LEK1,
1060	bool Modify=true) {
1061	intersectAndWarn(FSet1, FSet2, JoinLoc, LEK1, LEK1, Modify);
1062	}
1063
1064	void runAnalysis(AnalysisDeclContext &AC);
1065	};
1066
1067	} // namespace
1068
1069	/// Process acquired_before and acquired_after attributes on Vd.
1070	BeforeSet::BeforeInfo* BeforeSet::insertAttrExprs(const ValueDecl* Vd,
1071	ThreadSafetyAnalyzer& Analyzer) {
1072	// Create a new entry for Vd.
1073	BeforeInfo *Info = nullptr;
1074	{
1075	// Keep InfoPtr in its own scope in case BMap is modified later and the
1076	// reference becomes invalid.
1077	std::unique_ptr<BeforeInfo> &InfoPtr = BMap[Vd];
1078	if (!InfoPtr)
1079	InfoPtr.reset(new BeforeInfo());
1080	Info = InfoPtr.get();
1081	}
1082
1083	for (const auto *At : Vd->attrs()) {
1084	switch (At->getKind()) {
1085	case attr::AcquiredBefore: {
1086	const auto *A = cast<AcquiredBeforeAttr>(At);
1087
1088	// Read exprs from the attribute, and add them to BeforeVect.
1089	for (const auto *Arg : A->args()) {
1090	CapabilityExpr Cp =
1091	Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
1092	if (const ValueDecl *Cpvd = Cp.valueDecl()) {
1093	Info->Vect.push_back(Cpvd);
1094	const auto It = BMap.find(Cpvd);
1095	if (It == BMap.end())
1096	insertAttrExprs(Cpvd, Analyzer);
1097	}
1098	}
1099	break;
1100	}
1101	case attr::AcquiredAfter: {
1102	const auto *A = cast<AcquiredAfterAttr>(At);
1103
1104	// Read exprs from the attribute, and add them to BeforeVect.
1105	for (const auto *Arg : A->args()) {
1106	CapabilityExpr Cp =
1107	Analyzer.SxBuilder.translateAttrExpr(Arg, nullptr);
1108	if (const ValueDecl *ArgVd = Cp.valueDecl()) {
1109	// Get entry for mutex listed in attribute
1110	BeforeInfo *ArgInfo = getBeforeInfoForDecl(ArgVd, Analyzer);
1111	ArgInfo->Vect.push_back(Vd);
1112	}
1113	}
1114	break;
1115	}
1116	default:
1117	break;
1118	}
1119	}
1120
1121	return Info;
1122	}
1123
1124	BeforeSet::BeforeInfo *
1125	BeforeSet::getBeforeInfoForDecl(const ValueDecl *Vd,
1126	ThreadSafetyAnalyzer &Analyzer) {
1127	auto It = BMap.find(Vd);
1128	BeforeInfo *Info = nullptr;
1129	if (It == BMap.end())
1130	Info = insertAttrExprs(Vd, Analyzer);
1131	else
1132	Info = It->second.get();
1133	(0) . __assert_fail ("Info && \"BMap contained nullptr?\"", "/home/seafit/code_projects/clang_source/clang/lib/Analysis/ThreadSafety.cpp", 1133, __PRETTY_FUNCTION__))" file_link="../../../include/assert.h.html#88" macro="true">assert(Info && "BMap contained nullptr?");
1134	return Info;
1135	}
1136
1137	/// Return true if any mutexes in FSet are in the acquired_before set of Vd.
1138	void BeforeSet::checkBeforeAfter(const ValueDecl* StartVd,
1139	const FactSet& FSet,
1140	ThreadSafetyAnalyzer& Analyzer,
1141	SourceLocation Loc, StringRef CapKind) {
1142	SmallVector<BeforeInfo*, 8> InfoVect;
1143
1144	// Do a depth-first traversal of Vd.
1145	// Return true if there are cycles.
1146	std::function<bool (const ValueDecl)> traverse = [&](const ValueDecl Vd) {
1147	if (!Vd)
1148	return false;
1149
1150	BeforeSet::BeforeInfo *Info = getBeforeInfoForDecl(Vd, Analyzer);
1151
1152	if (Info->Visited == 1)
1153	return true;
1154
1155	if (Info->Visited == 2)
1156	return false;
1157
1158	if (Info->Vect.empty())
1159	return false;
1160
1161	InfoVect.push_back(Info);
1162	Info->Visited = 1;
1163	for (const auto *Vdb : Info->Vect) {
1164	// Exclude mutexes in our immediate before set.
1165	if (FSet.containsMutexDecl(Analyzer.FactMan, Vdb)) {
1166	StringRef L1 = StartVd->getName();
1167	StringRef L2 = Vdb->getName();
1168	Analyzer.Handler.handleLockAcquiredBefore(CapKind, L1, L2, Loc);
1169	}
1170	// Transitively search other before sets, and warn on cycles.
1171	if (traverse(Vdb)) {
1172	if (CycMap.find(Vd) == CycMap.end()) {
1173	CycMap.insert(std::make_pair(Vd, true));
1174	StringRef L1 = Vd->getName();
1175	Analyzer.Handler.handleBeforeAfterCycle(L1, Vd->getLocation());
1176	}
1177	}
1178	}
1179	Info->Visited = 2;
1180	return false;
1181	};
1182
1183	traverse(StartVd);
1184
1185	for (auto *Info : InfoVect)
1186	Info->Visited = 0;
1187	}
1188
1189	/// Gets the value decl pointer from DeclRefExprs or MemberExprs.
1190	static const ValueDecl getValueDecl(const Expr Exp) {
1191	if (const auto *CE = dyn_cast<ImplicitCastExpr>(Exp))
1192	return getValueDecl(CE->getSubExpr());
1193
1194	if (const auto *DR = dyn_cast<DeclRefExpr>(Exp))
1195	return DR->getDecl();
1196
1197	if (const auto *ME = dyn_cast<MemberExpr>(Exp))
1198	return ME->getMemberDecl();
1199
1200	return nullptr;
1201	}
1202
1203	namespace {
1204
1205	template <typename Ty>
1206	class has_arg_iterator_range {
1207	using yes = char[1];
1208	using no = char[2];
1209
1210	template <typename Inner>
1211	static yes& test(Inner I, decltype(I->args()) = nullptr);
1212
1213	template <typename>
1214	static no& test(...);
1215
1216	public:
1217	static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
1218	};
1219
1220	} // namespace
1221
1222	static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
1223	return A->getName();
1224	}
1225
1226	static StringRef ClassifyDiagnostic(QualType VDT) {
1227	// We need to look at the declaration of the type of the value to determine
1228	// which it is. The type should either be a record or a typedef, or a pointer
1229	// or reference thereof.
1230	if (const auto *RT = VDT->getAs<RecordType>()) {
1231	if (const auto *RD = RT->getDecl())
1232	if (const auto *CA = RD->getAttr<CapabilityAttr>())
1233	return ClassifyDiagnostic(CA);
1234	} else if (const auto *TT = VDT->getAs<TypedefType>()) {
1235	if (const auto *TD = TT->getDecl())
1236	if (const auto *CA = TD->getAttr<CapabilityAttr>())
1237	return ClassifyDiagnostic(CA);
1238	} else if (VDT->isPointerType() \|\| VDT->isReferenceType())
1239	return ClassifyDiagnostic(VDT->getPointeeType());
1240
1241	return "mutex";
1242	}
1243
1244	static StringRef ClassifyDiagnostic(const ValueDecl *VD) {
1245	(0) . __assert_fail ("VD && \"No ValueDecl passed\"", "/home/seafit/code_projects/clang_source/clang/lib/Analysis/ThreadSafety.cpp", 1245, __PRETTY_FUNCTION__))" file_link="../../../include/assert.h.html#88" macro="true">assert(VD && "No ValueDecl passed");
1246
1247	// The ValueDecl is the declaration of a mutex or role (hopefully).
1248	return ClassifyDiagnostic(VD->getType());
1249	}
1250
1251	template <typename AttrTy>
1252	static typename std::enable_if<!has_arg_iterator_range<AttrTy>::value,
1253	StringRef>::type
1254	ClassifyDiagnostic(const AttrTy *A) {
1255	if (const ValueDecl *VD = getValueDecl(A->getArg()))
1256	return ClassifyDiagnostic(VD);
1257	return "mutex";
1258	}
1259
1260	template <typename AttrTy>
1261	static typename std::enable_if<has_arg_iterator_range<AttrTy>::value,
1262	StringRef>::type
1263	ClassifyDiagnostic(const AttrTy *A) {
1264	for (const auto *Arg : A->args()) {
1265	if (const ValueDecl *VD = getValueDecl(Arg))
1266	return ClassifyDiagnostic(VD);
1267	}
1268	return "mutex";
1269	}
1270
1271	bool ThreadSafetyAnalyzer::inCurrentScope(const CapabilityExpr &CapE) {
1272	if (!CurrentMethod)
1273	return false;
1274	if (const auto *P = dyn_cast_or_null<til::Project>(CapE.sexpr())) {
1275	const auto *VD = P->clangDecl();
1276	if (VD)
1277	return VD->getDeclContext() == CurrentMethod->getDeclContext();
1278	}
1279	return false;
1280	}
1281
1282	/// Add a new lock to the lockset, warning if the lock is already there.
1283	/// \param ReqAttr -- true if this is part of an initial Requires attribute.
1284	void ThreadSafetyAnalyzer::addLock(FactSet &FSet,
1285	std::unique_ptr<FactEntry> Entry,
1286	StringRef DiagKind, bool ReqAttr) {
1287	if (Entry->shouldIgnore())
1288	return;
1289
1290	if (!ReqAttr && !Entry->negative()) {
1291	// look for the negative capability, and remove it from the fact set.
1292	CapabilityExpr NegC = !*Entry;
1293	const FactEntry *Nen = FSet.findLock(FactMan, NegC);
1294	if (Nen) {
1295	FSet.removeLock(FactMan, NegC);
1296	}
1297	else {
1298	if (inCurrentScope(*Entry) && !Entry->asserted())
1299	Handler.handleNegativeNotHeld(DiagKind, Entry->toString(),
1300	NegC.toString(), Entry->loc());
1301	}
1302	}
1303
1304	// Check before/after constraints
1305	if (Handler.issueBetaWarnings() &&
1306	!Entry->asserted() && !Entry->declared()) {
1307	GlobalBeforeSet->checkBeforeAfter(Entry->valueDecl(), FSet, *this,
1308	Entry->loc(), DiagKind);
1309	}
1310
1311	// FIXME: Don't always warn when we have support for reentrant locks.
1312	if (const FactEntry Cp = FSet.findLock(FactMan, Entry)) {
1313	if (!Entry->asserted())
1314	Cp->handleLock(FSet, FactMan, *Entry, Handler, DiagKind);
1315	} else {
1316	FSet.addLock(FactMan, std::move(Entry));
1317	}
1318	}
1319
1320	/// Remove a lock from the lockset, warning if the lock is not there.
1321	/// \param UnlockLoc The source location of the unlock (only used in error msg)
1322	void ThreadSafetyAnalyzer::removeLock(FactSet &FSet, const CapabilityExpr &Cp,
1323	SourceLocation UnlockLoc,
1324	bool FullyRemove, LockKind ReceivedKind,
1325	StringRef DiagKind) {
1326	if (Cp.shouldIgnore())
1327	return;
1328
1329	const FactEntry *LDat = FSet.findLock(FactMan, Cp);
1330	if (!LDat) {
1331	Handler.handleUnmatchedUnlock(DiagKind, Cp.toString(), UnlockLoc);
1332	return;
1333	}
1334
1335	// Generic lock removal doesn't care about lock kind mismatches, but
1336	// otherwise diagnose when the lock kinds are mismatched.
1337	if (ReceivedKind != LK_Generic && LDat->kind() != ReceivedKind) {
1338	Handler.handleIncorrectUnlockKind(DiagKind, Cp.toString(), LDat->kind(),
1339	ReceivedKind, LDat->loc(), UnlockLoc);
1340	}
1341
1342	LDat->handleUnlock(FSet, FactMan, Cp, UnlockLoc, FullyRemove, Handler,
1343	DiagKind);
1344	}
1345
1346	/// Extract the list of mutexIDs from the attribute on an expression,
1347	/// and push them onto Mtxs, discarding any duplicates.
1348	template <typename AttrType>
1349	void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1350	const Expr Exp, const NamedDecl D,
1351	VarDecl *SelfDecl) {
1352	if (Attr->args_size() == 0) {
1353	// The mutex held is the "this" object.
1354	CapabilityExpr Cp = SxBuilder.translateAttrExpr(nullptr, D, Exp, SelfDecl);
1355	if (Cp.isInvalid()) {
1356	warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1357	return;
1358	}
1359	//else
1360	if (!Cp.shouldIgnore())
1361	Mtxs.push_back_nodup(Cp);
1362	return;
1363	}
1364
1365	for (const auto *Arg : Attr->args()) {
1366	CapabilityExpr Cp = SxBuilder.translateAttrExpr(Arg, D, Exp, SelfDecl);
1367	if (Cp.isInvalid()) {
1368	warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1369	continue;
1370	}
1371	//else
1372	if (!Cp.shouldIgnore())
1373	Mtxs.push_back_nodup(Cp);
1374	}
1375	}
1376
1377	/// Extract the list of mutexIDs from a trylock attribute. If the
1378	/// trylock applies to the given edge, then push them onto Mtxs, discarding
1379	/// any duplicates.
1380	template <class AttrType>
1381	void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1382	const Expr Exp, const NamedDecl D,
1383	const CFGBlock *PredBlock,
1384	const CFGBlock *CurrBlock,
1385	Expr *BrE, bool Neg) {
1386	// Find out which branch has the lock
1387	bool branch = false;
1388	if (const auto *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE))
1389	branch = BLE->getValue();
1390	else if (const auto *ILE = dyn_cast_or_null<IntegerLiteral>(BrE))
1391	branch = ILE->getValue().getBoolValue();
1392
1393	int branchnum = branch ? 0 : 1;
1394	if (Neg)
1395	branchnum = !branchnum;
1396
1397	// If we've taken the trylock branch, then add the lock
1398	int i = 0;
1399	for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1400	SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1401	if (*SI == CurrBlock && i == branchnum)
1402	getMutexIDs(Mtxs, Attr, Exp, D);
1403	}
1404	}
1405
1406	static bool getStaticBooleanValue(Expr *E, bool &TCond) {
1407	if (isa<CXXNullPtrLiteralExpr>(E) \|\| isa<GNUNullExpr>(E)) {
1408	TCond = false;
1409	return true;
1410	} else if (const auto *BLE = dyn_cast<CXXBoolLiteralExpr>(E)) {
1411	TCond = BLE->getValue();
1412	return true;
1413	} else if (const auto *ILE = dyn_cast<IntegerLiteral>(E)) {
1414	TCond = ILE->getValue().getBoolValue();
1415	return true;
1416	} else if (auto *CE = dyn_cast<ImplicitCastExpr>(E))
1417	return getStaticBooleanValue(CE->getSubExpr(), TCond);
1418	return false;
1419	}
1420
1421	// If Cond can be traced back to a function call, return the call expression.
1422	// The negate variable should be called with false, and will be set to true
1423	// if the function call is negated, e.g. if (!mu.tryLock(...))
1424	const CallExpr* ThreadSafetyAnalyzer::getTrylockCallExpr(const Stmt *Cond,
1425	LocalVarContext C,
1426	bool &Negate) {
1427	if (!Cond)
1428	return nullptr;
1429
1430	if (const auto *CallExp = dyn_cast<CallExpr>(Cond)) {
1431	if (CallExp->getBuiltinCallee() == Builtin::BI__builtin_expect)
1432	return getTrylockCallExpr(CallExp->getArg(0), C, Negate);
1433	return CallExp;
1434	}
1435	else if (const auto *PE = dyn_cast<ParenExpr>(Cond))
1436	return getTrylockCallExpr(PE->getSubExpr(), C, Negate);
1437	else if (const auto *CE = dyn_cast<ImplicitCastExpr>(Cond))
1438	return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1439	else if (const auto *FE = dyn_cast<FullExpr>(Cond))
1440	return getTrylockCallExpr(FE->getSubExpr(), C, Negate);
1441	else if (const auto *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1442	const Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1443	return getTrylockCallExpr(E, C, Negate);
1444	}
1445	else if (const auto *UOP = dyn_cast<UnaryOperator>(Cond)) {
1446	if (UOP->getOpcode() == UO_LNot) {
1447	Negate = !Negate;
1448	return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1449	}
1450	return nullptr;
1451	}
1452	else if (const auto *BOP = dyn_cast<BinaryOperator>(Cond)) {
1453	if (BOP->getOpcode() == BO_EQ \|\| BOP->getOpcode() == BO_NE) {
1454	if (BOP->getOpcode() == BO_NE)
1455	Negate = !Negate;
1456
1457	bool TCond = false;
1458	if (getStaticBooleanValue(BOP->getRHS(), TCond)) {
1459	if (!TCond) Negate = !Negate;
1460	return getTrylockCallExpr(BOP->getLHS(), C, Negate);
1461	}
1462	TCond = false;
1463	if (getStaticBooleanValue(BOP->getLHS(), TCond)) {
1464	if (!TCond) Negate = !Negate;
1465	return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1466	}
1467	return nullptr;
1468	}
1469	if (BOP->getOpcode() == BO_LAnd) {
1470	// LHS must have been evaluated in a different block.
1471	return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1472	}
1473	if (BOP->getOpcode() == BO_LOr)
1474	return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1475	return nullptr;
1476	} else if (const auto *COP = dyn_cast<ConditionalOperator>(Cond)) {
1477	bool TCond, FCond;
1478	if (getStaticBooleanValue(COP->getTrueExpr(), TCond) &&
1479	getStaticBooleanValue(COP->getFalseExpr(), FCond)) {
1480	if (TCond && !FCond)
1481	return getTrylockCallExpr(COP->getCond(), C, Negate);
1482	if (!TCond && FCond) {
1483	Negate = !Negate;
1484	return getTrylockCallExpr(COP->getCond(), C, Negate);
1485	}
1486	}
1487	}
1488	return nullptr;
1489	}
1490
1491	/// Find the lockset that holds on the edge between PredBlock
1492	/// and CurrBlock. The edge set is the exit set of PredBlock (passed
1493	/// as the ExitSet parameter) plus any trylocks, which are conditionally held.
1494	void ThreadSafetyAnalyzer::getEdgeLockset(FactSet& Result,
1495	const FactSet &ExitSet,
1496	const CFGBlock *PredBlock,
1497	const CFGBlock *CurrBlock) {
1498	Result = ExitSet;
1499
1500	const Stmt *Cond = PredBlock->getTerminatorCondition();
1501	// We don't acquire try-locks on ?: branches, only when its result is used.
1502	if (!Cond \|\| isa<ConditionalOperator>(PredBlock->getTerminator()))
1503	return;
1504
1505	bool Negate = false;
1506	const CFGBlockInfo *PredBlockInfo = &BlockInfo[PredBlock->getBlockID()];
1507	const LocalVarContext &LVarCtx = PredBlockInfo->ExitContext;
1508	StringRef CapDiagKind = "mutex";
1509
1510	const auto *Exp = getTrylockCallExpr(Cond, LVarCtx, Negate);
1511	if (!Exp)
1512	return;
1513
1514	auto *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1515	if(!FunDecl \|\| !FunDecl->hasAttrs())
1516	return;
1517
1518	CapExprSet ExclusiveLocksToAdd;
1519	CapExprSet SharedLocksToAdd;
1520
1521	// If the condition is a call to a Trylock function, then grab the attributes
1522	for (const auto *Attr : FunDecl->attrs()) {
1523	switch (Attr->getKind()) {
1524	case attr::TryAcquireCapability: {
1525	auto *A = cast<TryAcquireCapabilityAttr>(Attr);
1526	getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
1527	Exp, FunDecl, PredBlock, CurrBlock, A->getSuccessValue(),
1528	Negate);
1529	CapDiagKind = ClassifyDiagnostic(A);
1530	break;
1531	};
1532	case attr::ExclusiveTrylockFunction: {
1533	const auto *A = cast<ExclusiveTrylockFunctionAttr>(Attr);
1534	getMutexIDs(ExclusiveLocksToAdd, A, Exp, FunDecl,
1535	PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1536	CapDiagKind = ClassifyDiagnostic(A);
1537	break;
1538	}
1539	case attr::SharedTrylockFunction: {
1540	const auto *A = cast<SharedTrylockFunctionAttr>(Attr);
1541	getMutexIDs(SharedLocksToAdd, A, Exp, FunDecl,
1542	PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1543	CapDiagKind = ClassifyDiagnostic(A);
1544	break;
1545	}
1546	default:
1547	break;
1548	}
1549	}
1550
1551	// Add and remove locks.
1552	SourceLocation Loc = Exp->getExprLoc();
1553	for (const auto &ExclusiveLockToAdd : ExclusiveLocksToAdd)
1554	addLock(Result, llvm::make_unique<LockableFactEntry>(ExclusiveLockToAdd,
1555	LK_Exclusive, Loc),
1556	CapDiagKind);
1557	for (const auto &SharedLockToAdd : SharedLocksToAdd)
1558	addLock(Result, llvm::make_unique<LockableFactEntry>(SharedLockToAdd,
1559	LK_Shared, Loc),
1560	CapDiagKind);
1561	}
1562
1563	namespace {
1564
1565	/// We use this class to visit different types of expressions in
1566	/// CFGBlocks, and build up the lockset.
1567	/// An expression may cause us to add or remove locks from the lockset, or else
1568	/// output error messages related to missing locks.
1569	/// FIXME: In future, we may be able to not inherit from a visitor.
1570	class BuildLockset : public ConstStmtVisitor<BuildLockset> {
1571	friend class ThreadSafetyAnalyzer;
1572
1573	ThreadSafetyAnalyzer *Analyzer;
1574	FactSet FSet;
1575	LocalVariableMap::Context LVarCtx;
1576	unsigned CtxIndex;
1577
1578	// helper functions
1579	void warnIfMutexNotHeld(const NamedDecl D, const Expr Exp, AccessKind AK,
1580	Expr *MutexExp, ProtectedOperationKind POK,
1581	StringRef DiagKind, SourceLocation Loc);
1582	void warnIfMutexHeld(const NamedDecl D, const Expr Exp, Expr *MutexExp,
1583	StringRef DiagKind);
1584
1585	void checkAccess(const Expr *Exp, AccessKind AK,
1586	ProtectedOperationKind POK = POK_VarAccess);
1587	void checkPtAccess(const Expr *Exp, AccessKind AK,
1588	ProtectedOperationKind POK = POK_VarAccess);
1589
1590	void handleCall(const Expr Exp, const NamedDecl D, VarDecl *VD = nullptr);
1591	void examineArguments(const FunctionDecl *FD,
1592	CallExpr::const_arg_iterator ArgBegin,
1593	CallExpr::const_arg_iterator ArgEnd,
1594	bool SkipFirstParam = false);
1595
1596	public:
1597	BuildLockset(ThreadSafetyAnalyzer *Anlzr, CFGBlockInfo &Info)
1598	: ConstStmtVisitor<BuildLockset>(), Analyzer(Anlzr), FSet(Info.EntrySet),
1599	LVarCtx(Info.EntryContext), CtxIndex(Info.EntryIndex) {}
1600
1601	void VisitUnaryOperator(const UnaryOperator *UO);
1602	void VisitBinaryOperator(const BinaryOperator *BO);
1603	void VisitCastExpr(const CastExpr *CE);
1604	void VisitCallExpr(const CallExpr *Exp);
1605	void VisitCXXConstructExpr(const CXXConstructExpr *Exp);
1606	void VisitDeclStmt(const DeclStmt *S);
1607	};
1608
1609	} // namespace
1610
1611	/// Warn if the LSet does not contain a lock sufficient to protect access
1612	/// of at least the passed in AccessKind.
1613	void BuildLockset::warnIfMutexNotHeld(const NamedDecl D, const Expr Exp,
1614	AccessKind AK, Expr *MutexExp,
1615	ProtectedOperationKind POK,
1616	StringRef DiagKind, SourceLocation Loc) {
1617	LockKind LK = getLockKindFromAccessKind(AK);
1618
1619	CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1620	if (Cp.isInvalid()) {
1621	warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1622	return;
1623	} else if (Cp.shouldIgnore()) {
1624	return;
1625	}
1626
1627	if (Cp.negative()) {
1628	// Negative capabilities act like locks excluded
1629	const FactEntry *LDat = FSet.findLock(Analyzer->FactMan, !Cp);
1630	if (LDat) {
1631	Analyzer->Handler.handleFunExcludesLock(
1632	DiagKind, D->getNameAsString(), (!Cp).toString(), Loc);
1633	return;
1634	}
1635
1636	// If this does not refer to a negative capability in the same class,
1637	// then stop here.
1638	if (!Analyzer->inCurrentScope(Cp))
1639	return;
1640
1641	// Otherwise the negative requirement must be propagated to the caller.
1642	LDat = FSet.findLock(Analyzer->FactMan, Cp);
1643	if (!LDat) {
1644	Analyzer->Handler.handleMutexNotHeld("", D, POK, Cp.toString(),
1645	LK_Shared, Loc);
1646	}
1647	return;
1648	}
1649
1650	const FactEntry *LDat = FSet.findLockUniv(Analyzer->FactMan, Cp);
1651	bool NoError = true;
1652	if (!LDat) {
1653	// No exact match found. Look for a partial match.
1654	LDat = FSet.findPartialMatch(Analyzer->FactMan, Cp);
1655	if (LDat) {
1656	// Warn that there's no precise match.
1657	std::string PartMatchStr = LDat->toString();
1658	StringRef PartMatchName(PartMatchStr);
1659	Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1660	LK, Loc, &PartMatchName);
1661	} else {
1662	// Warn that there's no match at all.
1663	Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1664	LK, Loc);
1665	}
1666	NoError = false;
1667	}
1668	// Make sure the mutex we found is the right kind.
1669	if (NoError && LDat && !LDat->isAtLeast(LK)) {
1670	Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1671	LK, Loc);
1672	}
1673	}
1674
1675	/// Warn if the LSet contains the given lock.
1676	void BuildLockset::warnIfMutexHeld(const NamedDecl D, const Expr Exp,
1677	Expr *MutexExp, StringRef DiagKind) {
1678	CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1679	if (Cp.isInvalid()) {
1680	warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1681	return;
1682	} else if (Cp.shouldIgnore()) {
1683	return;
1684	}
1685
1686	const FactEntry *LDat = FSet.findLock(Analyzer->FactMan, Cp);
1687	if (LDat) {
1688	Analyzer->Handler.handleFunExcludesLock(
1689	DiagKind, D->getNameAsString(), Cp.toString(), Exp->getExprLoc());
1690	}
1691	}
1692
1693	/// Checks guarded_by and pt_guarded_by attributes.
1694	/// Whenever we identify an access (read or write) to a DeclRefExpr that is
1695	/// marked with guarded_by, we must ensure the appropriate mutexes are held.
1696	/// Similarly, we check if the access is to an expression that dereferences
1697	/// a pointer marked with pt_guarded_by.
1698	void BuildLockset::checkAccess(const Expr *Exp, AccessKind AK,
1699	ProtectedOperationKind POK) {
1700	Exp = Exp->IgnoreImplicit()->IgnoreParenCasts();
1701
1702	SourceLocation Loc = Exp->getExprLoc();
1703
1704	// Local variables of reference type cannot be re-assigned;
1705	// map them to their initializer.
1706	while (const auto *DRE = dyn_cast<DeclRefExpr>(Exp)) {
1707	const auto *VD = dyn_cast<VarDecl>(DRE->getDecl()->getCanonicalDecl());
1708	if (VD && VD->isLocalVarDecl() && VD->getType()->isReferenceType()) {
1709	if (const auto *E = VD->getInit()) {
1710	// Guard against self-initialization. e.g., int &i = i;
1711	if (E == Exp)
1712	break;
1713	Exp = E;
1714	continue;
1715	}
1716	}
1717	break;
1718	}
1719
1720	if (const auto *UO = dyn_cast<UnaryOperator>(Exp)) {
1721	// For dereferences
1722	if (UO->getOpcode() == UO_Deref)
1723	checkPtAccess(UO->getSubExpr(), AK, POK);
1724	return;
1725	}
1726
1727	if (const auto *AE = dyn_cast<ArraySubscriptExpr>(Exp)) {
1728	checkPtAccess(AE->getLHS(), AK, POK);
1729	return;
1730	}
1731
1732	if (const auto *ME = dyn_cast<MemberExpr>(Exp)) {
1733	if (ME->isArrow())
1734	checkPtAccess(ME->getBase(), AK, POK);
1735	else
1736	checkAccess(ME->getBase(), AK, POK);
1737	}
1738
1739	const ValueDecl *D = getValueDecl(Exp);
1740	if (!D \|\| !D->hasAttrs())
1741	return;
1742
1743	if (D->hasAttr<GuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan)) {
1744	Analyzer->Handler.handleNoMutexHeld("mutex", D, POK, AK, Loc);
1745	}
1746
1747	for (const auto *I : D->specific_attrs<GuardedByAttr>())
1748	warnIfMutexNotHeld(D, Exp, AK, I->getArg(), POK,
1749	ClassifyDiagnostic(I), Loc);
1750	}
1751
1752	/// Checks pt_guarded_by and pt_guarded_var attributes.
1753	/// POK is the same operationKind that was passed to checkAccess.
1754	void BuildLockset::checkPtAccess(const Expr *Exp, AccessKind AK,
1755	ProtectedOperationKind POK) {
1756	while (true) {
1757	if (const auto *PE = dyn_cast<ParenExpr>(Exp)) {
1758	Exp = PE->getSubExpr();
1759	continue;
1760	}
1761	if (const auto *CE = dyn_cast<CastExpr>(Exp)) {
1762	if (CE->getCastKind() == CK_ArrayToPointerDecay) {
1763	// If it's an actual array, and not a pointer, then it's elements
1764	// are protected by GUARDED_BY, not PT_GUARDED_BY;
1765	checkAccess(CE->getSubExpr(), AK, POK);
1766	return;
1767	}
1768	Exp = CE->getSubExpr();
1769	continue;
1770	}
1771	break;
1772	}
1773
1774	// Pass by reference warnings are under a different flag.
1775	ProtectedOperationKind PtPOK = POK_VarDereference;
1776	if (POK == POK_PassByRef) PtPOK = POK_PtPassByRef;
1777
1778	const ValueDecl *D = getValueDecl(Exp);
1779	if (!D \|\| !D->hasAttrs())
1780	return;
1781
1782	if (D->hasAttr<PtGuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan))
1783	Analyzer->Handler.handleNoMutexHeld("mutex", D, PtPOK, AK,
1784	Exp->getExprLoc());
1785
1786	for (auto const *I : D->specific_attrs<PtGuardedByAttr>())
1787	warnIfMutexNotHeld(D, Exp, AK, I->getArg(), PtPOK,
1788	ClassifyDiagnostic(I), Exp->getExprLoc());
1789	}
1790
1791	/// Process a function call, method call, constructor call,
1792	/// or destructor call. This involves looking at the attributes on the
1793	/// corresponding function/method/constructor/destructor, issuing warnings,
1794	/// and updating the locksets accordingly.
1795	///
1796	/// FIXME: For classes annotated with one of the guarded annotations, we need
1797	/// to treat const method calls as reads and non-const method calls as writes,
1798	/// and check that the appropriate locks are held. Non-const method calls with
1799	/// the same signature as const method calls can be also treated as reads.
1800	///
1801	void BuildLockset::handleCall(const Expr Exp, const NamedDecl D,
1802	VarDecl *VD) {
1803	SourceLocation Loc = Exp->getExprLoc();
1804	CapExprSet ExclusiveLocksToAdd, SharedLocksToAdd;
1805	CapExprSet ExclusiveLocksToRemove, SharedLocksToRemove, GenericLocksToRemove;
1806	CapExprSet ScopedExclusiveReqs, ScopedSharedReqs;
1807	StringRef CapDiagKind = "mutex";
1808
1809	// Figure out if we're constructing an object of scoped lockable class
1810	bool isScopedVar = false;
1811	if (VD) {
1812	if (const auto *CD = dyn_cast<const CXXConstructorDecl>(D)) {
1813	const CXXRecordDecl* PD = CD->getParent();
1814	if (PD && PD->hasAttr<ScopedLockableAttr>())
1815	isScopedVar = true;
1816	}
1817	}
1818
1819	for(const Attr *At : D->attrs()) {
1820	switch (At->getKind()) {
1821	// When we encounter a lock function, we need to add the lock to our
1822	// lockset.
1823	case attr::AcquireCapability: {
1824	const auto *A = cast<AcquireCapabilityAttr>(At);
1825	Analyzer->getMutexIDs(A->isShared() ? SharedLocksToAdd
1826	: ExclusiveLocksToAdd,
1827	A, Exp, D, VD);
1828
1829	CapDiagKind = ClassifyDiagnostic(A);
1830	break;
1831	}
1832
1833	// An assert will add a lock to the lockset, but will not generate
1834	// a warning if it is already there, and will not generate a warning
1835	// if it is not removed.
1836	case attr::AssertExclusiveLock: {
1837	const auto *A = cast<AssertExclusiveLockAttr>(At);
1838
1839	CapExprSet AssertLocks;
1840	Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1841	for (const auto &AssertLock : AssertLocks)
1842	Analyzer->addLock(FSet,
1843	llvm::make_unique<LockableFactEntry>(
1844	AssertLock, LK_Exclusive, Loc, false, true),
1845	ClassifyDiagnostic(A));
1846	break;
1847	}
1848	case attr::AssertSharedLock: {
1849	const auto *A = cast<AssertSharedLockAttr>(At);
1850
1851	CapExprSet AssertLocks;
1852	Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1853	for (const auto &AssertLock : AssertLocks)
1854	Analyzer->addLock(FSet,
1855	llvm::make_unique<LockableFactEntry>(
1856	AssertLock, LK_Shared, Loc, false, true),
1857	ClassifyDiagnostic(A));
1858	break;
1859	}
1860
1861	case attr::AssertCapability: {
1862	const auto *A = cast<AssertCapabilityAttr>(At);
1863	CapExprSet AssertLocks;
1864	Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1865	for (const auto &AssertLock : AssertLocks)
1866	Analyzer->addLock(FSet,
1867	llvm::make_unique<LockableFactEntry>(
1868	AssertLock,
1869	A->isShared() ? LK_Shared : LK_Exclusive, Loc,
1870	false, true),
1871	ClassifyDiagnostic(A));
1872	break;
1873	}
1874
1875	// When we encounter an unlock function, we need to remove unlocked
1876	// mutexes from the lockset, and flag a warning if they are not there.
1877	case attr::ReleaseCapability: {
1878	const auto *A = cast<ReleaseCapabilityAttr>(At);
1879	if (A->isGeneric())
1880	Analyzer->getMutexIDs(GenericLocksToRemove, A, Exp, D, VD);
1881	else if (A->isShared())
1882	Analyzer->getMutexIDs(SharedLocksToRemove, A, Exp, D, VD);
1883	else
1884	Analyzer->getMutexIDs(ExclusiveLocksToRemove, A, Exp, D, VD);
1885
1886	CapDiagKind = ClassifyDiagnostic(A);
1887	break;
1888	}
1889
1890	case attr::RequiresCapability: {
1891	const auto *A = cast<RequiresCapabilityAttr>(At);
1892	for (auto *Arg : A->args()) {
1893	warnIfMutexNotHeld(D, Exp, A->isShared() ? AK_Read : AK_Written, Arg,
1894	POK_FunctionCall, ClassifyDiagnostic(A),
1895	Exp->getExprLoc());
1896	// use for adopting a lock
1897	if (isScopedVar) {
1898	Analyzer->getMutexIDs(A->isShared() ? ScopedSharedReqs
1899	: ScopedExclusiveReqs,
1900	A, Exp, D, VD);
1901	}
1902	}
1903	break;
1904	}
1905
1906	case attr::LocksExcluded: {
1907	const auto *A = cast<LocksExcludedAttr>(At);
1908	for (auto *Arg : A->args())
1909	warnIfMutexHeld(D, Exp, Arg, ClassifyDiagnostic(A));
1910	break;
1911	}
1912
1913	// Ignore attributes unrelated to thread-safety
1914	default:
1915	break;
1916	}
1917	}
1918
1919	// Remove locks first to allow lock upgrading/downgrading.
1920	// FIXME -- should only fully remove if the attribute refers to 'this'.
1921	bool Dtor = isa<CXXDestructorDecl>(D);
1922	for (const auto &M : ExclusiveLocksToRemove)
1923	Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Exclusive, CapDiagKind);
1924	for (const auto &M : SharedLocksToRemove)
1925	Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Shared, CapDiagKind);
1926	for (const auto &M : GenericLocksToRemove)
1927	Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Generic, CapDiagKind);
1928
1929	// Add locks.
1930	for (const auto &M : ExclusiveLocksToAdd)
1931	Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1932	M, LK_Exclusive, Loc, isScopedVar),
1933	CapDiagKind);
1934	for (const auto &M : SharedLocksToAdd)
1935	Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1936	M, LK_Shared, Loc, isScopedVar),
1937	CapDiagKind);
1938
1939	if (isScopedVar) {
1940	// Add the managing object as a dummy mutex, mapped to the underlying mutex.
1941	SourceLocation MLoc = VD->getLocation();
1942	DeclRefExpr DRE(VD->getASTContext(), VD, false, VD->getType(), VK_LValue,
1943	VD->getLocation());
1944	// FIXME: does this store a pointer to DRE?
1945	CapabilityExpr Scp = Analyzer->SxBuilder.translateAttrExpr(&DRE, nullptr);
1946
1947	auto ScopedEntry = llvm::make_unique<ScopedLockableFactEntry>(Scp, MLoc);
1948	for (const auto &M : ExclusiveLocksToAdd)
1949	ScopedEntry->addExclusiveLock(M);
1950	for (const auto &M : ScopedExclusiveReqs)
1951	ScopedEntry->addExclusiveLock(M);
1952	for (const auto &M : SharedLocksToAdd)
1953	ScopedEntry->addSharedLock(M);
1954	for (const auto &M : ScopedSharedReqs)
1955	ScopedEntry->addSharedLock(M);
1956	for (const auto &M : ExclusiveLocksToRemove)
1957	ScopedEntry->addExclusiveUnlock(M);
1958	for (const auto &M : SharedLocksToRemove)
1959	ScopedEntry->addSharedUnlock(M);
1960	Analyzer->addLock(FSet, std::move(ScopedEntry), CapDiagKind);
1961	}
1962	}
1963
1964	/// For unary operations which read and write a variable, we need to
1965	/// check whether we hold any required mutexes. Reads are checked in
1966	/// VisitCastExpr.
1967	void BuildLockset::VisitUnaryOperator(const UnaryOperator *UO) {
1968	switch (UO->getOpcode()) {
1969	case UO_PostDec:
1970	case UO_PostInc:
1971	case UO_PreDec:
1972	case UO_PreInc:
1973	checkAccess(UO->getSubExpr(), AK_Written);
1974	break;
1975	default:
1976	break;
1977	}
1978	}
1979
1980	/// For binary operations which assign to a variable (writes), we need to check
1981	/// whether we hold any required mutexes.
1982	/// FIXME: Deal with non-primitive types.
1983	void BuildLockset::VisitBinaryOperator(const BinaryOperator *BO) {
1984	if (!BO->isAssignmentOp())
1985	return;
1986
1987	// adjust the context
1988	LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
1989
1990	checkAccess(BO->getLHS(), AK_Written);
1991	}
1992
1993	/// Whenever we do an LValue to Rvalue cast, we are reading a variable and
1994	/// need to ensure we hold any required mutexes.
1995	/// FIXME: Deal with non-primitive types.
1996	void BuildLockset::VisitCastExpr(const CastExpr *CE) {
1997	if (CE->getCastKind() != CK_LValueToRValue)
1998	return;
1999	checkAccess(CE->getSubExpr(), AK_Read);
2000	}
2001
2002	void BuildLockset::examineArguments(const FunctionDecl *FD,
2003	CallExpr::const_arg_iterator ArgBegin,
2004	CallExpr::const_arg_iterator ArgEnd,
2005	bool SkipFirstParam) {
2006	// Currently we can't do anything if we don't know the function declaration.
2007	if (!FD)
2008	return;
2009
2010	// NO_THREAD_SAFETY_ANALYSIS does double duty here. Normally it
2011	// only turns off checking within the body of a function, but we also
2012	// use it to turn off checking in arguments to the function. This
2013	// could result in some false negatives, but the alternative is to
2014	// create yet another attribute.
2015	if (FD->hasAttr<NoThreadSafetyAnalysisAttr>())
2016	return;
2017
2018	const ArrayRef<ParmVarDecl *> Params = FD->parameters();
2019	auto Param = Params.begin();
2020	if (SkipFirstParam)
2021	++Param;
2022
2023	// There can be default arguments, so we stop when one iterator is at end().
2024	for (auto Arg = ArgBegin; Param != Params.end() && Arg != ArgEnd;
2025	++Param, ++Arg) {
2026	QualType Qt = (*Param)->getType();
2027	if (Qt->isReferenceType())
2028	checkAccess(*Arg, AK_Read, POK_PassByRef);
2029	}
2030	}
2031
2032	void BuildLockset::VisitCallExpr(const CallExpr *Exp) {
2033	if (const auto *CE = dyn_cast<CXXMemberCallExpr>(Exp)) {
2034	const auto *ME = dyn_cast<MemberExpr>(CE->getCallee());
2035	// ME can be null when calling a method pointer
2036	const CXXMethodDecl *MD = CE->getMethodDecl();
2037
2038	if (ME && MD) {
2039	if (ME->isArrow()) {
2040	if (MD->isConst())
2041	checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
2042	else // FIXME -- should be AK_Written
2043	checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
2044	} else {
2045	if (MD->isConst())
2046	checkAccess(CE->getImplicitObjectArgument(), AK_Read);
2047	else // FIXME -- should be AK_Written
2048	checkAccess(CE->getImplicitObjectArgument(), AK_Read);
2049	}
2050	}
2051
2052	examineArguments(CE->getDirectCallee(), CE->arg_begin(), CE->arg_end());
2053	} else if (const auto *OE = dyn_cast<CXXOperatorCallExpr>(Exp)) {
2054	auto OEop = OE->getOperator();
2055	switch (OEop) {
2056	case OO_Equal: {
2057	const Expr *Target = OE->getArg(0);
2058	const Expr *Source = OE->getArg(1);
2059	checkAccess(Target, AK_Written);
2060	checkAccess(Source, AK_Read);
2061	break;
2062	}
2063	case OO_Star:
2064	case OO_Arrow:
2065	case OO_Subscript:
2066	if (!(OEop == OO_Star && OE->getNumArgs() > 1)) {
2067	// Grrr. operator* can be multiplication...
2068	checkPtAccess(OE->getArg(0), AK_Read);
2069	}
2070	LLVM_FALLTHROUGH;
2071	default: {
2072	// TODO: get rid of this, and rely on pass-by-ref instead.
2073	const Expr *Obj = OE->getArg(0);
2074	checkAccess(Obj, AK_Read);
2075	// Check the remaining arguments. For method operators, the first
2076	// argument is the implicit self argument, and doesn't appear in the
2077	// FunctionDecl, but for non-methods it does.
2078	const FunctionDecl *FD = OE->getDirectCallee();
2079	examineArguments(FD, std::next(OE->arg_begin()), OE->arg_end(),
2080	/SkipFirstParam/ !isa<CXXMethodDecl>(FD));
2081	break;
2082	}
2083	}
2084	} else {
2085	examineArguments(Exp->getDirectCallee(), Exp->arg_begin(), Exp->arg_end());
2086	}
2087
2088	auto *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
2089	if(!D \|\| !D->hasAttrs())
2090	return;
2091	handleCall(Exp, D);
2092	}
2093
2094	void BuildLockset::VisitCXXConstructExpr(const CXXConstructExpr *Exp) {
2095	const CXXConstructorDecl *D = Exp->getConstructor();
2096	if (D && D->isCopyConstructor()) {
2097	const Expr* Source = Exp->getArg(0);
2098	checkAccess(Source, AK_Read);
2099	} else {
2100	examineArguments(D, Exp->arg_begin(), Exp->arg_end());
2101	}
2102	}
2103
2104	static CXXConstructorDecl *
2105	findConstructorForByValueReturn(const CXXRecordDecl *RD) {
2106	// Prefer a move constructor over a copy constructor. If there's more than
2107	// one copy constructor or more than one move constructor, we arbitrarily
2108	// pick the first declared such constructor rather than trying to guess which
2109	// one is more appropriate.
2110	CXXConstructorDecl *CopyCtor = nullptr;
2111	for (auto *Ctor : RD->ctors()) {
2112	if (Ctor->isDeleted())
2113	continue;
2114	if (Ctor->isMoveConstructor())
2115	return Ctor;
2116	if (!CopyCtor && Ctor->isCopyConstructor())
2117	CopyCtor = Ctor;
2118	}
2119	return CopyCtor;
2120	}
2121
2122	static Expr buildFakeCtorCall(CXXConstructorDecl CD, ArrayRef<Expr *> Args,
2123	SourceLocation Loc) {
2124	ASTContext &Ctx = CD->getASTContext();
2125	return CXXConstructExpr::Create(Ctx, Ctx.getRecordType(CD->getParent()), Loc,
2126	CD, true, Args, false, false, false, false,
2127	CXXConstructExpr::CK_Complete,
2128	SourceRange(Loc, Loc));
2129	}
2130
2131	void BuildLockset::VisitDeclStmt(const DeclStmt *S) {
2132	// adjust the context
2133	LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
2134
2135	for (auto *D : S->getDeclGroup()) {
2136	if (auto *VD = dyn_cast_or_null<VarDecl>(D)) {
2137	Expr *E = VD->getInit();
2138	if (!E)
2139	continue;
2140	E = E->IgnoreParens();
2141
2142	// handle constructors that involve temporaries
2143	if (auto *EWC = dyn_cast<ExprWithCleanups>(E))
2144	E = EWC->getSubExpr();
2145	if (auto *BTE = dyn_cast<CXXBindTemporaryExpr>(E))
2146	E = BTE->getSubExpr();
2147
2148	if (const auto *CE = dyn_cast<CXXConstructExpr>(E)) {
2149	const auto *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
2150	if (!CtorD \|\| !CtorD->hasAttrs())
2151	continue;
2152	handleCall(E, CtorD, VD);
2153	} else if (isa<CallExpr>(E) && E->isRValue()) {
2154	// If the object is initialized by a function call that returns a
2155	// scoped lockable by value, use the attributes on the copy or move
2156	// constructor to figure out what effect that should have on the
2157	// lockset.
2158	// FIXME: Is this really the best way to handle this situation?
2159	auto *RD = E->getType()->getAsCXXRecordDecl();
2160	if (!RD \|\| !RD->hasAttr<ScopedLockableAttr>())
2161	continue;
2162	CXXConstructorDecl *CtorD = findConstructorForByValueReturn(RD);
2163	if (!CtorD \|\| !CtorD->hasAttrs())
2164	continue;
2165	handleCall(buildFakeCtorCall(CtorD, {E}, E->getBeginLoc()), CtorD, VD);
2166	}
2167	}
2168	}
2169	}
2170
2171	/// Compute the intersection of two locksets and issue warnings for any
2172	/// locks in the symmetric difference.
2173	///
2174	/// This function is used at a merge point in the CFG when comparing the lockset
2175	/// of each branch being merged. For example, given the following sequence:
2176	/// A; if () then B; else C; D; we need to check that the lockset after B and C
2177	/// are the same. In the event of a difference, we use the intersection of these
2178	/// two locksets at the start of D.
2179	///
2180	/// \param FSet1 The first lockset.
2181	/// \param FSet2 The second lockset.
2182	/// \param JoinLoc The location of the join point for error reporting
2183	/// \param LEK1 The error message to report if a mutex is missing from LSet1
2184	/// \param LEK2 The error message to report if a mutex is missing from Lset2
2185	void ThreadSafetyAnalyzer::intersectAndWarn(FactSet &FSet1,
2186	const FactSet &FSet2,
2187	SourceLocation JoinLoc,
2188	LockErrorKind LEK1,
2189	LockErrorKind LEK2,
2190	bool Modify) {
2191	FactSet FSet1Orig = FSet1;
2192
2193	// Find locks in FSet2 that conflict or are not in FSet1, and warn.
2194	for (const auto &Fact : FSet2) {
2195	const FactEntry *LDat1 = nullptr;
2196	const FactEntry *LDat2 = &FactMan[Fact];
2197	FactSet::iterator Iter1 = FSet1.findLockIter(FactMan, *LDat2);
2198	if (Iter1 != FSet1.end()) LDat1 = &FactMan[*Iter1];
2199
2200	if (LDat1) {
2201	if (LDat1->kind() != LDat2->kind()) {
2202	Handler.handleExclusiveAndShared("mutex", LDat2->toString(),
2203	LDat2->loc(), LDat1->loc());
2204	if (Modify && LDat1->kind() != LK_Exclusive) {
2205	// Take the exclusive lock, which is the one in FSet2.
2206	*Iter1 = Fact;
2207	}
2208	}
2209	else if (Modify && LDat1->asserted() && !LDat2->asserted()) {
2210	// The non-asserted lock in FSet2 is the one we want to track.
2211	*Iter1 = Fact;
2212	}
2213	} else {
2214	LDat2->handleRemovalFromIntersection(FSet2, FactMan, JoinLoc, LEK1,
2215	Handler);
2216	}
2217	}
2218
2219	// Find locks in FSet1 that are not in FSet2, and remove them.
2220	for (const auto &Fact : FSet1Orig) {
2221	const FactEntry *LDat1 = &FactMan[Fact];
2222	const FactEntry LDat2 = FSet2.findLock(FactMan, LDat1);
2223
2224	if (!LDat2) {
2225	LDat1->handleRemovalFromIntersection(FSet1Orig, FactMan, JoinLoc, LEK2,
2226	Handler);
2227	if (Modify)
2228	FSet1.removeLock(FactMan, *LDat1);
2229	}
2230	}
2231	}
2232
2233	// Return true if block B never continues to its successors.
2234	static bool neverReturns(const CFGBlock *B) {
2235	if (B->hasNoReturnElement())
2236	return true;
2237	if (B->empty())
2238	return false;
2239
2240	CFGElement Last = B->back();
2241	if (Optional<CFGStmt> S = Last.getAs<CFGStmt>()) {
2242	if (isa<CXXThrowExpr>(S->getStmt()))
2243	return true;
2244	}
2245	return false;
2246	}
2247
2248	/// Check a function's CFG for thread-safety violations.
2249	///
2250	/// We traverse the blocks in the CFG, compute the set of mutexes that are held
2251	/// at the end of each block, and issue warnings for thread safety violations.
2252	/// Each block in the CFG is traversed exactly once.
2253	void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
2254	// TODO: this whole function needs be rewritten as a visitor for CFGWalker.
2255	// For now, we just use the walker to set things up.
2256	threadSafety::CFGWalker walker;
2257	if (!walker.init(AC))
2258	return;
2259
2260	// AC.dumpCFG(true);
2261	// threadSafety::printSCFG(walker);
2262
2263	CFG *CFGraph = walker.getGraph();
2264	const NamedDecl *D = walker.getDecl();
2265	const auto *CurrentFunction = dyn_cast<FunctionDecl>(D);
2266	CurrentMethod = dyn_cast<CXXMethodDecl>(D);
2267
2268	if (D->hasAttr<NoThreadSafetyAnalysisAttr>())
2269	return;
2270
2271	// FIXME: Do something a bit more intelligent inside constructor and
2272	// destructor code. Constructors and destructors must assume unique access
2273	// to 'this', so checks on member variable access is disabled, but we should
2274	// still enable checks on other objects.
2275	if (isa<CXXConstructorDecl>(D))
2276	return; // Don't check inside constructors.
2277	if (isa<CXXDestructorDecl>(D))
2278	return; // Don't check inside destructors.
2279
2280	Handler.enterFunction(CurrentFunction);
2281
2282	BlockInfo.resize(CFGraph->getNumBlockIDs(),
2283	CFGBlockInfo::getEmptyBlockInfo(LocalVarMap));
2284
2285	// We need to explore the CFG via a "topological" ordering.
2286	// That way, we will be guaranteed to have information about required
2287	// predecessor locksets when exploring a new block.
2288	const PostOrderCFGView *SortedGraph = walker.getSortedGraph();
2289	PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
2290
2291	// Mark entry block as reachable
2292	BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
2293
2294	// Compute SSA names for local variables
2295	LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
2296
2297	// Fill in source locations for all CFGBlocks.
2298	findBlockLocations(CFGraph, SortedGraph, BlockInfo);
2299
2300	CapExprSet ExclusiveLocksAcquired;
2301	CapExprSet SharedLocksAcquired;
2302	CapExprSet LocksReleased;
2303
2304	// Add locks from exclusive_locks_required and shared_locks_required
2305	// to initial lockset. Also turn off checking for lock and unlock functions.
2306	// FIXME: is there a more intelligent way to check lock/unlock functions?
2307	if (!SortedGraph->empty() && D->hasAttrs()) {
2308	const CFGBlock FirstBlock = SortedGraph->begin();
2309	FactSet &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
2310
2311	CapExprSet ExclusiveLocksToAdd;
2312	CapExprSet SharedLocksToAdd;
2313	StringRef CapDiagKind = "mutex";
2314
2315	SourceLocation Loc = D->getLocation();
2316	for (const auto *Attr : D->attrs()) {
2317	Loc = Attr->getLocation();
2318	if (const auto *A = dyn_cast<RequiresCapabilityAttr>(Attr)) {
2319	getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
2320	nullptr, D);
2321	CapDiagKind = ClassifyDiagnostic(A);
2322	} else if (const auto *A = dyn_cast<ReleaseCapabilityAttr>(Attr)) {
2323	// UNLOCK_FUNCTION() is used to hide the underlying lock implementation.
2324	// We must ignore such methods.
2325	if (A->args_size() == 0)
2326	return;
2327	getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
2328	nullptr, D);
2329	getMutexIDs(LocksReleased, A, nullptr, D);
2330	CapDiagKind = ClassifyDiagnostic(A);
2331	} else if (const auto *A = dyn_cast<AcquireCapabilityAttr>(Attr)) {
2332	if (A->args_size() == 0)
2333	return;
2334	getMutexIDs(A->isShared() ? SharedLocksAcquired
2335	: ExclusiveLocksAcquired,
2336	A, nullptr, D);
2337	CapDiagKind = ClassifyDiagnostic(A);
2338	} else if (isa<ExclusiveTrylockFunctionAttr>(Attr)) {
2339	// Don't try to check trylock functions for now.
2340	return;
2341	} else if (isa<SharedTrylockFunctionAttr>(Attr)) {
2342	// Don't try to check trylock functions for now.
2343	return;
2344	} else if (isa<TryAcquireCapabilityAttr>(Attr)) {
2345	// Don't try to check trylock functions for now.
2346	return;
2347	}
2348	}
2349
2350	// FIXME -- Loc can be wrong here.
2351	for (const auto &Mu : ExclusiveLocksToAdd) {
2352	auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Exclusive, Loc);
2353	Entry->setDeclared(true);
2354	addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2355	}
2356	for (const auto &Mu : SharedLocksToAdd) {
2357	auto Entry = llvm::make_unique<LockableFactEntry>(Mu, LK_Shared, Loc);
2358	Entry->setDeclared(true);
2359	addLock(InitialLockset, std::move(Entry), CapDiagKind, true);
2360	}
2361	}
2362
2363	for (const auto CurrBlock : SortedGraph) {
2364	unsigned CurrBlockID = CurrBlock->getBlockID();
2365	CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
2366
2367	// Use the default initial lockset in case there are no predecessors.
2368	VisitedBlocks.insert(CurrBlock);
2369
2370	// Iterate through the predecessor blocks and warn if the lockset for all
2371	// predecessors is not the same. We take the entry lockset of the current
2372	// block to be the intersection of all previous locksets.
2373	// FIXME: By keeping the intersection, we may output more errors in future
2374	// for a lock which is not in the intersection, but was in the union. We
2375	// may want to also keep the union in future. As an example, let's say
2376	// the intersection contains Mutex L, and the union contains L and M.
2377	// Later we unlock M. At this point, we would output an error because we
2378	// never locked M; although the real error is probably that we forgot to
2379	// lock M on all code paths. Conversely, let's say that later we lock M.
2380	// In this case, we should compare against the intersection instead of the
2381	// union because the real error is probably that we forgot to unlock M on
2382	// all code paths.
2383	bool LocksetInitialized = false;
2384	SmallVector<CFGBlock *, 8> SpecialBlocks;
2385	for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
2386	PE = CurrBlock->pred_end(); PI != PE; ++PI) {
2387	// if *PI -> CurrBlock is a back edge
2388	if (PI == nullptr \|\| !VisitedBlocks.alreadySet(PI))
2389	continue;
2390
2391	unsigned PrevBlockID = (*PI)->getBlockID();
2392	CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2393
2394	// Ignore edges from blocks that can't return.
2395	if (neverReturns(*PI) \|\| !PrevBlockInfo->Reachable)
2396	continue;
2397
2398	// Okay, we can reach this block from the entry.
2399	CurrBlockInfo->Reachable = true;
2400
2401	// If the previous block ended in a 'continue' or 'break' statement, then
2402	// a difference in locksets is probably due to a bug in that block, rather
2403	// than in some other predecessor. In that case, keep the other
2404	// predecessor's lockset.
2405	if (const Stmt Terminator = (PI)->getTerminator()) {
2406	if (isa<ContinueStmt>(Terminator) \|\| isa<BreakStmt>(Terminator)) {
2407	SpecialBlocks.push_back(*PI);
2408	continue;
2409	}
2410	}
2411
2412	FactSet PrevLockset;
2413	getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
2414
2415	if (!LocksetInitialized) {
2416	CurrBlockInfo->EntrySet = PrevLockset;
2417	LocksetInitialized = true;
2418	} else {
2419	intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2420	CurrBlockInfo->EntryLoc,
2421	LEK_LockedSomePredecessors);
2422	}
2423	}
2424
2425	// Skip rest of block if it's not reachable.
2426	if (!CurrBlockInfo->Reachable)
2427	continue;
2428
2429	// Process continue and break blocks. Assume that the lockset for the
2430	// resulting block is unaffected by any discrepancies in them.
2431	for (const auto *PrevBlock : SpecialBlocks) {
2432	unsigned PrevBlockID = PrevBlock->getBlockID();
2433	CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2434
2435	if (!LocksetInitialized) {
2436	CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
2437	LocksetInitialized = true;
2438	} else {
2439	// Determine whether this edge is a loop terminator for diagnostic
2440	// purposes. FIXME: A 'break' statement might be a loop terminator, but
2441	// it might also be part of a switch. Also, a subsequent destructor
2442	// might add to the lockset, in which case the real issue might be a
2443	// double lock on the other path.
2444	const Stmt *Terminator = PrevBlock->getTerminator();
2445	bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
2446
2447	FactSet PrevLockset;
2448	getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet,
2449	PrevBlock, CurrBlock);
2450
2451	// Do not update EntrySet.
2452	intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2453	PrevBlockInfo->ExitLoc,
2454	IsLoop ? LEK_LockedSomeLoopIterations
2455	: LEK_LockedSomePredecessors,
2456	false);
2457	}
2458	}
2459
2460	BuildLockset LocksetBuilder(this, *CurrBlockInfo);
2461
2462	// Visit all the statements in the basic block.
2463	for (const auto &BI : *CurrBlock) {
2464	switch (BI.getKind()) {
2465	case CFGElement::Statement: {
2466	CFGStmt CS = BI.castAs<CFGStmt>();
2467	LocksetBuilder.Visit(CS.getStmt());
2468	break;
2469	}
2470	// Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
2471	case CFGElement::AutomaticObjectDtor: {
2472	CFGAutomaticObjDtor AD = BI.castAs<CFGAutomaticObjDtor>();
2473	const auto *DD = AD.getDestructorDecl(AC.getASTContext());
2474	if (!DD->hasAttrs())
2475	break;
2476
2477	// Create a dummy expression,
2478	auto VD = const_cast<VarDecl >(AD.getVarDecl());
2479	DeclRefExpr DRE(VD->getASTContext(), VD, false,
2480	VD->getType().getNonReferenceType(), VK_LValue,
2481	AD.getTriggerStmt()->getEndLoc());
2482	LocksetBuilder.handleCall(&DRE, DD);
2483	break;
2484	}
2485	default:
2486	break;
2487	}
2488	}
2489	CurrBlockInfo->ExitSet = LocksetBuilder.FSet;
2490
2491	// For every back edge from CurrBlock (the end of the loop) to another block
2492	// (FirstLoopBlock) we need to check that the Lockset of Block is equal to
2493	// the one held at the beginning of FirstLoopBlock. We can look up the
2494	// Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
2495	for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
2496	SE = CurrBlock->succ_end(); SI != SE; ++SI) {
2497	// if CurrBlock -> SI is not* a back edge
2498	if (SI == nullptr \|\| !VisitedBlocks.alreadySet(SI))
2499	continue;
2500
2501	CFGBlock FirstLoopBlock = SI;
2502	CFGBlockInfo *PreLoop = &BlockInfo[FirstLoopBlock->getBlockID()];
2503	CFGBlockInfo *LoopEnd = &BlockInfo[CurrBlockID];
2504	intersectAndWarn(LoopEnd->ExitSet, PreLoop->EntrySet,
2505	PreLoop->EntryLoc,
2506	LEK_LockedSomeLoopIterations,
2507	false);
2508	}
2509	}
2510
2511	CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
2512	CFGBlockInfo *Final = &BlockInfo[CFGraph->getExit().getBlockID()];
2513
2514	// Skip the final check if the exit block is unreachable.
2515	if (!Final->Reachable)
2516	return;
2517
2518	// By default, we expect all locks held on entry to be held on exit.
2519	FactSet ExpectedExitSet = Initial->EntrySet;
2520
2521	// Adjust the expected exit set by adding or removing locks, as declared
2522	// by *-LOCK_FUNCTION and UNLOCK_FUNCTION. The intersect below will then
2523	// issue the appropriate warning.
2524	// FIXME: the location here is not quite right.
2525	for (const auto &Lock : ExclusiveLocksAcquired)
2526	ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2527	Lock, LK_Exclusive, D->getLocation()));
2528	for (const auto &Lock : SharedLocksAcquired)
2529	ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2530	Lock, LK_Shared, D->getLocation()));
2531	for (const auto &Lock : LocksReleased)
2532	ExpectedExitSet.removeLock(FactMan, Lock);
2533
2534	// FIXME: Should we call this function for all blocks which exit the function?
2535	intersectAndWarn(ExpectedExitSet, Final->ExitSet,
2536	Final->ExitLoc,
2537	LEK_LockedAtEndOfFunction,
2538	LEK_NotLockedAtEndOfFunction,
2539	false);
2540
2541	Handler.leaveFunction(CurrentFunction);
2542	}
2543
2544	/// Check a function's CFG for thread-safety violations.
2545	///
2546	/// We traverse the blocks in the CFG, compute the set of mutexes that are held
2547	/// at the end of each block, and issue warnings for thread safety violations.
2548	/// Each block in the CFG is traversed exactly once.
2549	void threadSafety::runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2550	ThreadSafetyHandler &Handler,
2551	BeforeSet **BSet) {
2552	if (!*BSet)
2553	*BSet = new BeforeSet;
2554	ThreadSafetyAnalyzer Analyzer(Handler, *BSet);
2555	Analyzer.runAnalysis(AC);
2556	}
2557
2558	void threadSafety::threadSafetyCleanup(BeforeSet *Cache) { delete Cache; }
2559
2560	/// Helper function that returns a LockKind required for the given level
2561	/// of access.
2562	LockKind threadSafety::getLockKindFromAccessKind(AccessKind AK) {
2563	switch (AK) {
2564	case AK_Read :
2565	return LK_Shared;
2566	case AK_Written :
2567	return LK_Exclusive;
2568	}
2569	llvm_unreachable("Unknown AccessKind");
2570	}
2571

clang::threadSafety::BeforeSet::BeforeInfo

clang::threadSafety::BeforeSet::BMap

clang::threadSafety::BeforeSet::CycMap

Clang Project