Bug Summary

File:tools/clang/include/clang/Analysis/Analyses/ThreadSafetyCommon.h
Warning:line 367, column 5
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ThreadSafety.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-8/lib/clang/8.0.0 -D CLANG_VENDOR="Debian " -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/tools/clang/lib/Analysis -I /build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis -I /build/llvm-toolchain-snapshot-8~svn350071/tools/clang/include -I /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn350071/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/tools/clang/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-8~svn350071=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-12-27-042839-1215-1 -x c++ /build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp -faddrsig

/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp

1//===- ThreadSafety.cpp ---------------------------------------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// A intra-procedural analysis for thread safety (e.g. deadlocks and race
11// conditions), based off of an annotation system.
12//
13// See http://clang.llvm.org/docs/ThreadSafetyAnalysis.html
14// for more information.
15//
16//===----------------------------------------------------------------------===//
17
18#include "clang/Analysis/Analyses/ThreadSafety.h"
19#include "clang/AST/Attr.h"
20#include "clang/AST/Decl.h"
21#include "clang/AST/DeclCXX.h"
22#include "clang/AST/DeclGroup.h"
23#include "clang/AST/Expr.h"
24#include "clang/AST/ExprCXX.h"
25#include "clang/AST/OperationKinds.h"
26#include "clang/AST/Stmt.h"
27#include "clang/AST/StmtVisitor.h"
28#include "clang/AST/Type.h"
29#include "clang/Analysis/Analyses/PostOrderCFGView.h"
30#include "clang/Analysis/Analyses/ThreadSafetyCommon.h"
31#include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
32#include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
33#include "clang/Analysis/Analyses/ThreadSafetyUtil.h"
34#include "clang/Analysis/AnalysisDeclContext.h"
35#include "clang/Analysis/CFG.h"
36#include "clang/Basic/Builtins.h"
37#include "clang/Basic/LLVM.h"
38#include "clang/Basic/OperatorKinds.h"
39#include "clang/Basic/SourceLocation.h"
40#include "clang/Basic/Specifiers.h"
41#include "llvm/ADT/ArrayRef.h"
42#include "llvm/ADT/DenseMap.h"
43#include "llvm/ADT/ImmutableMap.h"
44#include "llvm/ADT/Optional.h"
45#include "llvm/ADT/PointerIntPair.h"
46#include "llvm/ADT/STLExtras.h"
47#include "llvm/ADT/SmallVector.h"
48#include "llvm/ADT/StringRef.h"
49#include "llvm/Support/Allocator.h"
50#include "llvm/Support/Casting.h"
51#include "llvm/Support/ErrorHandling.h"
52#include "llvm/Support/raw_ostream.h"
53#include <algorithm>
54#include <cassert>
55#include <functional>
56#include <iterator>
57#include <memory>
58#include <string>
59#include <type_traits>
60#include <utility>
61#include <vector>
62
63using namespace clang;
64using namespace threadSafety;
65
66// Key method definition
67ThreadSafetyHandler::~ThreadSafetyHandler() = default;
68
69/// Issue a warning about an invalid lock expression
70static void warnInvalidLock(ThreadSafetyHandler &Handler,
71 const Expr *MutexExp, const NamedDecl *D,
72 const Expr *DeclExp, StringRef Kind) {
73 SourceLocation Loc;
74 if (DeclExp)
75 Loc = DeclExp->getExprLoc();
76
77 // FIXME: add a note about the attribute location in MutexExp or D
78 if (Loc.isValid())
79 Handler.handleInvalidLockExp(Kind, Loc);
80}
81
82namespace {
83
84/// A set of CapabilityExpr objects, which are compiled from thread safety
85/// attributes on a function.
86class CapExprSet : public SmallVector<CapabilityExpr, 4> {
87public:
88 /// Push M onto list, but discard duplicates.
89 void push_back_nodup(const CapabilityExpr &CapE) {
90 iterator It = std::find_if(begin(), end(),
91 [=](const CapabilityExpr &CapE2) {
92 return CapE.equals(CapE2);
93 });
94 if (It == end())
95 push_back(CapE);
96 }
97};
98
99class FactManager;
100class FactSet;
101
102/// This is a helper class that stores a fact that is known at a
103/// particular point in program execution. Currently, a fact is a capability,
104/// along with additional information, such as where it was acquired, whether
105/// it is exclusive or shared, etc.
106///
107/// FIXME: this analysis does not currently support re-entrant locking.
108class FactEntry : public CapabilityExpr {
109private:
110 /// Exclusive or shared.
111 LockKind LKind;
112
113 /// Where it was acquired.
114 SourceLocation AcquireLoc;
115
116 /// True if the lock was asserted.
117 bool Asserted;
118
119 /// True if the lock was declared.
120 bool Declared;
121
122public:
123 FactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
124 bool Asrt, bool Declrd = false)
125 : CapabilityExpr(CE), LKind(LK), AcquireLoc(Loc), Asserted(Asrt),
126 Declared(Declrd) {}
127 virtual ~FactEntry() = default;
128
129 LockKind kind() const { return LKind; }
130 SourceLocation loc() const { return AcquireLoc; }
131 bool asserted() const { return Asserted; }
132 bool declared() const { return Declared; }
133
134 void setDeclared(bool D) { Declared = D; }
135
136 virtual void
137 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
138 SourceLocation JoinLoc, LockErrorKind LEK,
139 ThreadSafetyHandler &Handler) const = 0;
140 virtual void handleLock(FactSet &FSet, FactManager &FactMan,
141 const FactEntry &entry, ThreadSafetyHandler &Handler,
142 StringRef DiagKind) const = 0;
143 virtual void handleUnlock(FactSet &FSet, FactManager &FactMan,
144 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
145 bool FullyRemove, ThreadSafetyHandler &Handler,
146 StringRef DiagKind) const = 0;
147
148 // Return true if LKind >= LK, where exclusive > shared
149 bool isAtLeast(LockKind LK) const {
150 return (LKind == LK_Exclusive) || (LK == LK_Shared);
151 }
152};
153
154using FactID = unsigned short;
155
156/// FactManager manages the memory for all facts that are created during
157/// the analysis of a single routine.
158class FactManager {
159private:
160 std::vector<std::unique_ptr<const FactEntry>> Facts;
161
162public:
163 FactID newFact(std::unique_ptr<FactEntry> Entry) {
164 Facts.push_back(std::move(Entry));
165 return static_cast<unsigned short>(Facts.size() - 1);
166 }
167
168 const FactEntry &operator[](FactID F) const { return *Facts[F]; }
169};
170
171/// A FactSet is the set of facts that are known to be true at a
172/// particular program point. FactSets must be small, because they are
173/// frequently copied, and are thus implemented as a set of indices into a
174/// table maintained by a FactManager. A typical FactSet only holds 1 or 2
175/// locks, so we can get away with doing a linear search for lookup. Note
176/// that a hashtable or map is inappropriate in this case, because lookups
177/// may involve partial pattern matches, rather than exact matches.
178class FactSet {
179private:
180 using FactVec = SmallVector<FactID, 4>;
181
182 FactVec FactIDs;
183
184public:
185 using iterator = FactVec::iterator;
186 using const_iterator = FactVec::const_iterator;
187
188 iterator begin() { return FactIDs.begin(); }
189 const_iterator begin() const { return FactIDs.begin(); }
190
191 iterator end() { return FactIDs.end(); }
192 const_iterator end() const { return FactIDs.end(); }
193
194 bool isEmpty() const { return FactIDs.size() == 0; }
195
196 // Return true if the set contains only negative facts
197 bool isEmpty(FactManager &FactMan) const {
198 for (const auto FID : *this) {
199 if (!FactMan[FID].negative())
200 return false;
201 }
202 return true;
203 }
204
205 void addLockByID(FactID ID) { FactIDs.push_back(ID); }
206
207 FactID addLock(FactManager &FM, std::unique_ptr<FactEntry> Entry) {
208 FactID F = FM.newFact(std::move(Entry));
209 FactIDs.push_back(F);
210 return F;
211 }
212
213 bool removeLock(FactManager& FM, const CapabilityExpr &CapE) {
214 unsigned n = FactIDs.size();
215 if (n == 0)
216 return false;
217
218 for (unsigned i = 0; i < n-1; ++i) {
219 if (FM[FactIDs[i]].matches(CapE)) {
220 FactIDs[i] = FactIDs[n-1];
221 FactIDs.pop_back();
222 return true;
223 }
224 }
225 if (FM[FactIDs[n-1]].matches(CapE)) {
226 FactIDs.pop_back();
227 return true;
228 }
229 return false;
230 }
231
232 iterator findLockIter(FactManager &FM, const CapabilityExpr &CapE) {
233 return std::find_if(begin(), end(), [&](FactID ID) {
234 return FM[ID].matches(CapE);
235 });
236 }
237
238 const FactEntry *findLock(FactManager &FM, const CapabilityExpr &CapE) const {
239 auto I = std::find_if(begin(), end(), [&](FactID ID) {
240 return FM[ID].matches(CapE);
241 });
242 return I != end() ? &FM[*I] : nullptr;
243 }
244
245 const FactEntry *findLockUniv(FactManager &FM,
246 const CapabilityExpr &CapE) const {
247 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
248 return FM[ID].matchesUniv(CapE);
249 });
250 return I != end() ? &FM[*I] : nullptr;
251 }
252
253 const FactEntry *findPartialMatch(FactManager &FM,
254 const CapabilityExpr &CapE) const {
255 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
256 return FM[ID].partiallyMatches(CapE);
257 });
258 return I != end() ? &FM[*I] : nullptr;
259 }
260
261 bool containsMutexDecl(FactManager &FM, const ValueDecl* Vd) const {
262 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
263 return FM[ID].valueDecl() == Vd;
264 });
265 return I != end();
266 }
267};
268
269class ThreadSafetyAnalyzer;
270
271} // namespace
272
273namespace clang {
274namespace threadSafety {
275
276class BeforeSet {
277private:
278 using BeforeVect = SmallVector<const ValueDecl *, 4>;
279
280 struct BeforeInfo {
281 BeforeVect Vect;
282 int Visited = 0;
283
284 BeforeInfo() = default;
285 BeforeInfo(BeforeInfo &&) = default;
286 };
287
288 using BeforeMap =
289 llvm::DenseMap<const ValueDecl *, std::unique_ptr<BeforeInfo>>;
290 using CycleMap = llvm::DenseMap<const ValueDecl *, bool>;
291
292public:
293 BeforeSet() = default;
294
295 BeforeInfo* insertAttrExprs(const ValueDecl* Vd,
296 ThreadSafetyAnalyzer& Analyzer);
297
298 BeforeInfo *getBeforeInfoForDecl(const ValueDecl *Vd,
299 ThreadSafetyAnalyzer &Analyzer);
300
301 void checkBeforeAfter(const ValueDecl* Vd,
302 const FactSet& FSet,
303 ThreadSafetyAnalyzer& Analyzer,
304 SourceLocation Loc, StringRef CapKind);
305
306private:
307 BeforeMap BMap;
308 CycleMap CycMap;
309};
310
311} // namespace threadSafety
312} // namespace clang
313
314namespace {
315
316class LocalVariableMap;
317
318using LocalVarContext = llvm::ImmutableMap<const NamedDecl *, unsigned>;
319
320/// A side (entry or exit) of a CFG node.
321enum CFGBlockSide { CBS_Entry, CBS_Exit };
322
323/// CFGBlockInfo is a struct which contains all the information that is
324/// maintained for each block in the CFG. See LocalVariableMap for more
325/// information about the contexts.
326struct CFGBlockInfo {
327 // Lockset held at entry to block
328 FactSet EntrySet;
329
330 // Lockset held at exit from block
331 FactSet ExitSet;
332
333 // Context held at entry to block
334 LocalVarContext EntryContext;
335
336 // Context held at exit from block
337 LocalVarContext ExitContext;
338
339 // Location of first statement in block
340 SourceLocation EntryLoc;
341
342 // Location of last statement in block.
343 SourceLocation ExitLoc;
344
345 // Used to replay contexts later
346 unsigned EntryIndex;
347
348 // Is this block reachable?
349 bool Reachable = false;
350
351 const FactSet &getSet(CFGBlockSide Side) const {
352 return Side == CBS_Entry ? EntrySet : ExitSet;
353 }
354
355 SourceLocation getLocation(CFGBlockSide Side) const {
356 return Side == CBS_Entry ? EntryLoc : ExitLoc;
357 }
358
359private:
360 CFGBlockInfo(LocalVarContext EmptyCtx)
361 : EntryContext(EmptyCtx), ExitContext(EmptyCtx) {}
362
363public:
364 static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
365};
366
367// A LocalVariableMap maintains a map from local variables to their currently
368// valid definitions. It provides SSA-like functionality when traversing the
369// CFG. Like SSA, each definition or assignment to a variable is assigned a
370// unique name (an integer), which acts as the SSA name for that definition.
371// The total set of names is shared among all CFG basic blocks.
372// Unlike SSA, we do not rewrite expressions to replace local variables declrefs
373// with their SSA-names. Instead, we compute a Context for each point in the
374// code, which maps local variables to the appropriate SSA-name. This map
375// changes with each assignment.
376//
377// The map is computed in a single pass over the CFG. Subsequent analyses can
378// then query the map to find the appropriate Context for a statement, and use
379// that Context to look up the definitions of variables.
380class LocalVariableMap {
381public:
382 using Context = LocalVarContext;
383
384 /// A VarDefinition consists of an expression, representing the value of the
385 /// variable, along with the context in which that expression should be
386 /// interpreted. A reference VarDefinition does not itself contain this
387 /// information, but instead contains a pointer to a previous VarDefinition.
388 struct VarDefinition {
389 public:
390 friend class LocalVariableMap;
391
392 // The original declaration for this variable.
393 const NamedDecl *Dec;
394
395 // The expression for this variable, OR
396 const Expr *Exp = nullptr;
397
398 // Reference to another VarDefinition
399 unsigned Ref = 0;
400
401 // The map with which Exp should be interpreted.
402 Context Ctx;
403
404 bool isReference() { return !Exp; }
405
406 private:
407 // Create ordinary variable definition
408 VarDefinition(const NamedDecl *D, const Expr *E, Context C)
409 : Dec(D), Exp(E), Ctx(C) {}
410
411 // Create reference to previous definition
412 VarDefinition(const NamedDecl *D, unsigned R, Context C)
413 : Dec(D), Ref(R), Ctx(C) {}
414 };
415
416private:
417 Context::Factory ContextFactory;
418 std::vector<VarDefinition> VarDefinitions;
419 std::vector<unsigned> CtxIndices;
420 std::vector<std::pair<const Stmt *, Context>> SavedContexts;
421
422public:
423 LocalVariableMap() {
424 // index 0 is a placeholder for undefined variables (aka phi-nodes).
425 VarDefinitions.push_back(VarDefinition(nullptr, 0u, getEmptyContext()));
426 }
427
428 /// Look up a definition, within the given context.
429 const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
430 const unsigned *i = Ctx.lookup(D);
431 if (!i)
432 return nullptr;
433 assert(*i < VarDefinitions.size())((*i < VarDefinitions.size()) ? static_cast<void> (0
) : __assert_fail ("*i < VarDefinitions.size()", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 433, __PRETTY_FUNCTION__))
;
434 return &VarDefinitions[*i];
435 }
436
437 /// Look up the definition for D within the given context. Returns
438 /// NULL if the expression is not statically known. If successful, also
439 /// modifies Ctx to hold the context of the return Expr.
440 const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
441 const unsigned *P = Ctx.lookup(D);
442 if (!P)
443 return nullptr;
444
445 unsigned i = *P;
446 while (i > 0) {
447 if (VarDefinitions[i].Exp) {
448 Ctx = VarDefinitions[i].Ctx;
449 return VarDefinitions[i].Exp;
450 }
451 i = VarDefinitions[i].Ref;
452 }
453 return nullptr;
454 }
455
456 Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
457
458 /// Return the next context after processing S. This function is used by
459 /// clients of the class to get the appropriate context when traversing the
460 /// CFG. It must be called for every assignment or DeclStmt.
461 Context getNextContext(unsigned &CtxIndex, const Stmt *S, Context C) {
462 if (SavedContexts[CtxIndex+1].first == S) {
463 CtxIndex++;
464 Context Result = SavedContexts[CtxIndex].second;
465 return Result;
466 }
467 return C;
468 }
469
470 void dumpVarDefinitionName(unsigned i) {
471 if (i == 0) {
472 llvm::errs() << "Undefined";
473 return;
474 }
475 const NamedDecl *Dec = VarDefinitions[i].Dec;
476 if (!Dec) {
477 llvm::errs() << "<<NULL>>";
478 return;
479 }
480 Dec->printName(llvm::errs());
481 llvm::errs() << "." << i << " " << ((const void*) Dec);
482 }
483
484 /// Dumps an ASCII representation of the variable map to llvm::errs()
485 void dump() {
486 for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
487 const Expr *Exp = VarDefinitions[i].Exp;
488 unsigned Ref = VarDefinitions[i].Ref;
489
490 dumpVarDefinitionName(i);
491 llvm::errs() << " = ";
492 if (Exp) Exp->dump();
493 else {
494 dumpVarDefinitionName(Ref);
495 llvm::errs() << "\n";
496 }
497 }
498 }
499
500 /// Dumps an ASCII representation of a Context to llvm::errs()
501 void dumpContext(Context C) {
502 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
503 const NamedDecl *D = I.getKey();
504 D->printName(llvm::errs());
505 const unsigned *i = C.lookup(D);
506 llvm::errs() << " -> ";
507 dumpVarDefinitionName(*i);
508 llvm::errs() << "\n";
509 }
510 }
511
512 /// Builds the variable map.
513 void traverseCFG(CFG *CFGraph, const PostOrderCFGView *SortedGraph,
514 std::vector<CFGBlockInfo> &BlockInfo);
515
516protected:
517 friend class VarMapBuilder;
518
519 // Get the current context index
520 unsigned getContextIndex() { return SavedContexts.size()-1; }
521
522 // Save the current context for later replay
523 void saveContext(const Stmt *S, Context C) {
524 SavedContexts.push_back(std::make_pair(S, C));
525 }
526
527 // Adds a new definition to the given context, and returns a new context.
528 // This method should be called when declaring a new variable.
529 Context addDefinition(const NamedDecl *D, const Expr *Exp, Context Ctx) {
530 assert(!Ctx.contains(D))((!Ctx.contains(D)) ? static_cast<void> (0) : __assert_fail
("!Ctx.contains(D)", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 530, __PRETTY_FUNCTION__))
;
531 unsigned newID = VarDefinitions.size();
532 Context NewCtx = ContextFactory.add(Ctx, D, newID);
533 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
534 return NewCtx;
535 }
536
537 // Add a new reference to an existing definition.
538 Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
539 unsigned newID = VarDefinitions.size();
540 Context NewCtx = ContextFactory.add(Ctx, D, newID);
541 VarDefinitions.push_back(VarDefinition(D, i, Ctx));
542 return NewCtx;
543 }
544
545 // Updates a definition only if that definition is already in the map.
546 // This method should be called when assigning to an existing variable.
547 Context updateDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
548 if (Ctx.contains(D)) {
549 unsigned newID = VarDefinitions.size();
550 Context NewCtx = ContextFactory.remove(Ctx, D);
551 NewCtx = ContextFactory.add(NewCtx, D, newID);
552 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
553 return NewCtx;
554 }
555 return Ctx;
556 }
557
558 // Removes a definition from the context, but keeps the variable name
559 // as a valid variable. The index 0 is a placeholder for cleared definitions.
560 Context clearDefinition(const NamedDecl *D, Context Ctx) {
561 Context NewCtx = Ctx;
562 if (NewCtx.contains(D)) {
563 NewCtx = ContextFactory.remove(NewCtx, D);
564 NewCtx = ContextFactory.add(NewCtx, D, 0);
565 }
566 return NewCtx;
567 }
568
569 // Remove a definition entirely frmo the context.
570 Context removeDefinition(const NamedDecl *D, Context Ctx) {
571 Context NewCtx = Ctx;
572 if (NewCtx.contains(D)) {
573 NewCtx = ContextFactory.remove(NewCtx, D);
574 }
575 return NewCtx;
576 }
577
578 Context intersectContexts(Context C1, Context C2);
579 Context createReferenceContext(Context C);
580 void intersectBackEdge(Context C1, Context C2);
581};
582
583} // namespace
584
585// This has to be defined after LocalVariableMap.
586CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
587 return CFGBlockInfo(M.getEmptyContext());
588}
589
590namespace {
591
592/// Visitor which builds a LocalVariableMap
593class VarMapBuilder : public ConstStmtVisitor<VarMapBuilder> {
594public:
595 LocalVariableMap* VMap;
596 LocalVariableMap::Context Ctx;
597
598 VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
599 : VMap(VM), Ctx(C) {}
600
601 void VisitDeclStmt(const DeclStmt *S);
602 void VisitBinaryOperator(const BinaryOperator *BO);
603};
604
605} // namespace
606
607// Add new local variables to the variable map
608void VarMapBuilder::VisitDeclStmt(const DeclStmt *S) {
609 bool modifiedCtx = false;
610 const DeclGroupRef DGrp = S->getDeclGroup();
611 for (const auto *D : DGrp) {
612 if (const auto *VD = dyn_cast_or_null<VarDecl>(D)) {
613 const Expr *E = VD->getInit();
614
615 // Add local variables with trivial type to the variable map
616 QualType T = VD->getType();
617 if (T.isTrivialType(VD->getASTContext())) {
618 Ctx = VMap->addDefinition(VD, E, Ctx);
619 modifiedCtx = true;
620 }
621 }
622 }
623 if (modifiedCtx)
624 VMap->saveContext(S, Ctx);
625}
626
627// Update local variable definitions in variable map
628void VarMapBuilder::VisitBinaryOperator(const BinaryOperator *BO) {
629 if (!BO->isAssignmentOp())
630 return;
631
632 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
633
634 // Update the variable map and current context.
635 if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
636 const ValueDecl *VDec = DRE->getDecl();
637 if (Ctx.lookup(VDec)) {
638 if (BO->getOpcode() == BO_Assign)
639 Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
640 else
641 // FIXME -- handle compound assignment operators
642 Ctx = VMap->clearDefinition(VDec, Ctx);
643 VMap->saveContext(BO, Ctx);
644 }
645 }
646}
647
648// Computes the intersection of two contexts. The intersection is the
649// set of variables which have the same definition in both contexts;
650// variables with different definitions are discarded.
651LocalVariableMap::Context
652LocalVariableMap::intersectContexts(Context C1, Context C2) {
653 Context Result = C1;
654 for (const auto &P : C1) {
655 const NamedDecl *Dec = P.first;
656 const unsigned *i2 = C2.lookup(Dec);
657 if (!i2) // variable doesn't exist on second path
658 Result = removeDefinition(Dec, Result);
659 else if (*i2 != P.second) // variable exists, but has different definition
660 Result = clearDefinition(Dec, Result);
661 }
662 return Result;
663}
664
665// For every variable in C, create a new variable that refers to the
666// definition in C. Return a new context that contains these new variables.
667// (We use this for a naive implementation of SSA on loop back-edges.)
668LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
669 Context Result = getEmptyContext();
670 for (const auto &P : C)
671 Result = addReference(P.first, P.second, Result);
672 return Result;
673}
674
675// This routine also takes the intersection of C1 and C2, but it does so by
676// altering the VarDefinitions. C1 must be the result of an earlier call to
677// createReferenceContext.
678void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
679 for (const auto &P : C1) {
680 unsigned i1 = P.second;
681 VarDefinition *VDef = &VarDefinitions[i1];
682 assert(VDef->isReference())((VDef->isReference()) ? static_cast<void> (0) : __assert_fail
("VDef->isReference()", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 682, __PRETTY_FUNCTION__))
;
683
684 const unsigned *i2 = C2.lookup(P.first);
685 if (!i2 || (*i2 != i1))
686 VDef->Ref = 0; // Mark this variable as undefined
687 }
688}
689
690// Traverse the CFG in topological order, so all predecessors of a block
691// (excluding back-edges) are visited before the block itself. At
692// each point in the code, we calculate a Context, which holds the set of
693// variable definitions which are visible at that point in execution.
694// Visible variables are mapped to their definitions using an array that
695// contains all definitions.
696//
697// At join points in the CFG, the set is computed as the intersection of
698// the incoming sets along each edge, E.g.
699//
700// { Context | VarDefinitions }
701// int x = 0; { x -> x1 | x1 = 0 }
702// int y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
703// if (b) x = 1; { x -> x2, y -> y1 | x2 = 1, y1 = 0, ... }
704// else x = 2; { x -> x3, y -> y1 | x3 = 2, x2 = 1, ... }
705// ... { y -> y1 (x is unknown) | x3 = 2, x2 = 1, ... }
706//
707// This is essentially a simpler and more naive version of the standard SSA
708// algorithm. Those definitions that remain in the intersection are from blocks
709// that strictly dominate the current block. We do not bother to insert proper
710// phi nodes, because they are not used in our analysis; instead, wherever
711// a phi node would be required, we simply remove that definition from the
712// context (E.g. x above).
713//
714// The initial traversal does not capture back-edges, so those need to be
715// handled on a separate pass. Whenever the first pass encounters an
716// incoming back edge, it duplicates the context, creating new definitions
717// that refer back to the originals. (These correspond to places where SSA
718// might have to insert a phi node.) On the second pass, these definitions are
719// set to NULL if the variable has changed on the back-edge (i.e. a phi
720// node was actually required.) E.g.
721//
722// { Context | VarDefinitions }
723// int x = 0, y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
724// while (b) { x -> x2, y -> y1 | [1st:] x2=x1; [2nd:] x2=NULL; }
725// x = x+1; { x -> x3, y -> y1 | x3 = x2 + 1, ... }
726// ... { y -> y1 | x3 = 2, x2 = 1, ... }
727void LocalVariableMap::traverseCFG(CFG *CFGraph,
728 const PostOrderCFGView *SortedGraph,
729 std::vector<CFGBlockInfo> &BlockInfo) {
730 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
731
732 CtxIndices.resize(CFGraph->getNumBlockIDs());
733
734 for (const auto *CurrBlock : *SortedGraph) {
735 unsigned CurrBlockID = CurrBlock->getBlockID();
736 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
737
738 VisitedBlocks.insert(CurrBlock);
739
740 // Calculate the entry context for the current block
741 bool HasBackEdges = false;
742 bool CtxInit = true;
743 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
744 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
745 // if *PI -> CurrBlock is a back edge, so skip it
746 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI)) {
747 HasBackEdges = true;
748 continue;
749 }
750
751 unsigned PrevBlockID = (*PI)->getBlockID();
752 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
753
754 if (CtxInit) {
755 CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
756 CtxInit = false;
757 }
758 else {
759 CurrBlockInfo->EntryContext =
760 intersectContexts(CurrBlockInfo->EntryContext,
761 PrevBlockInfo->ExitContext);
762 }
763 }
764
765 // Duplicate the context if we have back-edges, so we can call
766 // intersectBackEdges later.
767 if (HasBackEdges)
768 CurrBlockInfo->EntryContext =
769 createReferenceContext(CurrBlockInfo->EntryContext);
770
771 // Create a starting context index for the current block
772 saveContext(nullptr, CurrBlockInfo->EntryContext);
773 CurrBlockInfo->EntryIndex = getContextIndex();
774
775 // Visit all the statements in the basic block.
776 VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
777 for (const auto &BI : *CurrBlock) {
778 switch (BI.getKind()) {
779 case CFGElement::Statement: {
780 CFGStmt CS = BI.castAs<CFGStmt>();
781 VMapBuilder.Visit(CS.getStmt());
782 break;
783 }
784 default:
785 break;
786 }
787 }
788 CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
789
790 // Mark variables on back edges as "unknown" if they've been changed.
791 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
792 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
793 // if CurrBlock -> *SI is *not* a back edge
794 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
795 continue;
796
797 CFGBlock *FirstLoopBlock = *SI;
798 Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
799 Context LoopEnd = CurrBlockInfo->ExitContext;
800 intersectBackEdge(LoopBegin, LoopEnd);
801 }
802 }
803
804 // Put an extra entry at the end of the indexed context array
805 unsigned exitID = CFGraph->getExit().getBlockID();
806 saveContext(nullptr, BlockInfo[exitID].ExitContext);
807}
808
809/// Find the appropriate source locations to use when producing diagnostics for
810/// each block in the CFG.
811static void findBlockLocations(CFG *CFGraph,
812 const PostOrderCFGView *SortedGraph,
813 std::vector<CFGBlockInfo> &BlockInfo) {
814 for (const auto *CurrBlock : *SortedGraph) {
815 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
816
817 // Find the source location of the last statement in the block, if the
818 // block is not empty.
819 if (const Stmt *S = CurrBlock->getTerminator()) {
820 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getBeginLoc();
821 } else {
822 for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
823 BE = CurrBlock->rend(); BI != BE; ++BI) {
824 // FIXME: Handle other CFGElement kinds.
825 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
826 CurrBlockInfo->ExitLoc = CS->getStmt()->getBeginLoc();
827 break;
828 }
829 }
830 }
831
832 if (CurrBlockInfo->ExitLoc.isValid()) {
833 // This block contains at least one statement. Find the source location
834 // of the first statement in the block.
835 for (const auto &BI : *CurrBlock) {
836 // FIXME: Handle other CFGElement kinds.
837 if (Optional<CFGStmt> CS = BI.getAs<CFGStmt>()) {
838 CurrBlockInfo->EntryLoc = CS->getStmt()->getBeginLoc();
839 break;
840 }
841 }
842 } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
843 CurrBlock != &CFGraph->getExit()) {
844 // The block is empty, and has a single predecessor. Use its exit
845 // location.
846 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
847 BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
848 }
849 }
850}
851
852namespace {
853
854class LockableFactEntry : public FactEntry {
855private:
856 /// managed by ScopedLockable object
857 bool Managed;
858
859public:
860 LockableFactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
861 bool Mng = false, bool Asrt = false)
862 : FactEntry(CE, LK, Loc, Asrt), Managed(Mng) {}
863
864 void
865 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
866 SourceLocation JoinLoc, LockErrorKind LEK,
867 ThreadSafetyHandler &Handler) const override {
868 if (!Managed && !asserted() && !negative() && !isUniversal()) {
869 Handler.handleMutexHeldEndOfScope("mutex", toString(), loc(), JoinLoc,
870 LEK);
871 }
872 }
873
874 void handleLock(FactSet &FSet, FactManager &FactMan, const FactEntry &entry,
875 ThreadSafetyHandler &Handler,
876 StringRef DiagKind) const override {
877 Handler.handleDoubleLock(DiagKind, entry.toString(), entry.loc());
878 }
879
880 void handleUnlock(FactSet &FSet, FactManager &FactMan,
881 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
882 bool FullyRemove, ThreadSafetyHandler &Handler,
883 StringRef DiagKind) const override {
884 FSet.removeLock(FactMan, Cp);
885 if (!Cp.negative()) {
886 FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
887 !Cp, LK_Exclusive, UnlockLoc));
888 }
889 }
890};
891
892class ScopedLockableFactEntry : public FactEntry {
893private:
894 enum UnderlyingCapabilityKind {
895 UCK_Acquired, ///< Any kind of acquired capability.
896 UCK_ReleasedShared, ///< Shared capability that was released.
897 UCK_ReleasedExclusive, ///< Exclusive capability that was released.
898 };
899
900 using UnderlyingCapability =
901 llvm::PointerIntPair<const til::SExpr *, 2, UnderlyingCapabilityKind>;
902
903 SmallVector<UnderlyingCapability, 4> UnderlyingMutexes;
904
905public:
906 ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc)
907 : FactEntry(CE, LK_Exclusive, Loc, false) {}
908
909 void addExclusiveLock(const CapabilityExpr &M) {
910 UnderlyingMutexes.emplace_back(M.sexpr(), UCK_Acquired);
911 }
912
913 void addSharedLock(const CapabilityExpr &M) {
914 UnderlyingMutexes.emplace_back(M.sexpr(), UCK_Acquired);
915 }
916
917 void addExclusiveUnlock(const CapabilityExpr &M) {
918 UnderlyingMutexes.emplace_back(M.sexpr(), UCK_ReleasedExclusive);
919 }
920
921 void addSharedUnlock(const CapabilityExpr &M) {
922 UnderlyingMutexes.emplace_back(M.sexpr(), UCK_ReleasedShared);
923 }
924
925 void
926 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
927 SourceLocation JoinLoc, LockErrorKind LEK,
928 ThreadSafetyHandler &Handler) const override {
929 for (const auto &UnderlyingMutex : UnderlyingMutexes) {
930 const auto *Entry = FSet.findLock(
931 FactMan, CapabilityExpr(UnderlyingMutex.getPointer(), false));
932 if ((UnderlyingMutex.getInt() == UCK_Acquired && Entry) ||
933 (UnderlyingMutex.getInt() != UCK_Acquired && !Entry)) {
934 // If this scoped lock manages another mutex, and if the underlying
935 // mutex is still/not held, then warn about the underlying mutex.
936 Handler.handleMutexHeldEndOfScope(
937 "mutex", sx::toString(UnderlyingMutex.getPointer()), loc(), JoinLoc,
938 LEK);
939 }
940 }
941 }
942
943 void handleLock(FactSet &FSet, FactManager &FactMan, const FactEntry &entry,
944 ThreadSafetyHandler &Handler,
945 StringRef DiagKind) const override {
946 for (const auto &UnderlyingMutex : UnderlyingMutexes) {
947 CapabilityExpr UnderCp(UnderlyingMutex.getPointer(), false);
948
949 if (UnderlyingMutex.getInt() == UCK_Acquired)
950 lock(FSet, FactMan, UnderCp, entry.kind(), entry.loc(), &Handler,
951 DiagKind);
952 else
953 unlock(FSet, FactMan, UnderCp, entry.loc(), &Handler, DiagKind);
954 }
955 }
956
957 void handleUnlock(FactSet &FSet, FactManager &FactMan,
958 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
959 bool FullyRemove, ThreadSafetyHandler &Handler,
960 StringRef DiagKind) const override {
961 assert(!Cp.negative() && "Managing object cannot be negative.")((!Cp.negative() && "Managing object cannot be negative."
) ? static_cast<void> (0) : __assert_fail ("!Cp.negative() && \"Managing object cannot be negative.\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 961, __PRETTY_FUNCTION__))
;
962 for (const auto &UnderlyingMutex : UnderlyingMutexes) {
963 CapabilityExpr UnderCp(UnderlyingMutex.getPointer(), false);
964
965 // Remove/lock the underlying mutex if it exists/is still unlocked; warn
966 // on double unlocking/locking if we're not destroying the scoped object.
967 ThreadSafetyHandler *TSHandler = FullyRemove ? nullptr : &Handler;
968 if (UnderlyingMutex.getInt() == UCK_Acquired) {
969 unlock(FSet, FactMan, UnderCp, UnlockLoc, TSHandler, DiagKind);
970 } else {
971 LockKind kind = UnderlyingMutex.getInt() == UCK_ReleasedShared
972 ? LK_Shared
973 : LK_Exclusive;
974 lock(FSet, FactMan, UnderCp, kind, UnlockLoc, TSHandler, DiagKind);
975 }
976 }
977 if (FullyRemove)
978 FSet.removeLock(FactMan, Cp);
979 }
980
981private:
982 void lock(FactSet &FSet, FactManager &FactMan, const CapabilityExpr &Cp,
983 LockKind kind, SourceLocation loc, ThreadSafetyHandler *Handler,
984 StringRef DiagKind) const {
985 if (!FSet.findLock(FactMan, Cp)) {
986 FSet.removeLock(FactMan, !Cp);
987 FSet.addLock(FactMan,
988 llvm::make_unique<LockableFactEntry>(Cp, kind, loc));
989 } else if (Handler) {
990 Handler->handleDoubleLock(DiagKind, Cp.toString(), 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.
1008class 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
1024public:
1025 ThreadSafetyAnalyzer(ThreadSafetyHandler &H, BeforeSet* Bset)
1026 : Arena(&Bpa), SxBuilder(Arena), Handler(H), GlobalBeforeSet(Bset) {}
4
Calling constructor for 'SExprBuilder'
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.
1070BeforeSet::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
1124BeforeSet::BeforeInfo *
1125BeforeSet::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 assert(Info && "BMap contained nullptr?")((Info && "BMap contained nullptr?") ? static_cast<
void> (0) : __assert_fail ("Info && \"BMap contained nullptr?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 1133, __PRETTY_FUNCTION__))
;
1134 return Info;
1135}
1136
1137/// Return true if any mutexes in FSet are in the acquired_before set of Vd.
1138void 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.
1190static 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
1203namespace {
1204
1205template <typename Ty>
1206class 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
1216public:
1217 static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
1218};
1219
1220} // namespace
1221
1222static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
1223 return A->getName();
1224}
1225
1226static 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
1244static StringRef ClassifyDiagnostic(const ValueDecl *VD) {
1245 assert(VD && "No ValueDecl passed")((VD && "No ValueDecl passed") ? static_cast<void>
(0) : __assert_fail ("VD && \"No ValueDecl passed\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 1245, __PRETTY_FUNCTION__))
;
1246
1247 // The ValueDecl is the declaration of a mutex or role (hopefully).
1248 return ClassifyDiagnostic(VD->getType());
1249}
1250
1251template <typename AttrTy>
1252static typename std::enable_if<!has_arg_iterator_range<AttrTy>::value,
1253 StringRef>::type
1254ClassifyDiagnostic(const AttrTy *A) {
1255 if (const ValueDecl *VD = getValueDecl(A->getArg()))
1256 return ClassifyDiagnostic(VD);
1257 return "mutex";
1258}
1259
1260template <typename AttrTy>
1261static typename std::enable_if<has_arg_iterator_range<AttrTy>::value,
1262 StringRef>::type
1263ClassifyDiagnostic(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
1271bool 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.
1284void 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)
1322void 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(),
1339 LDat->kind(), ReceivedKind, 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.
1348template <typename AttrType>
1349void 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.
1380template <class AttrType>
1381void 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
1406static 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(...))
1424const 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.
1494void 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
1563namespace {
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.
1570class 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
1596public:
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.
1613void 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.
1676void 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.
1698void 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.
1754void 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///
1801void 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.
1967void 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.
1983void 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.
1996void BuildLockset::VisitCastExpr(const CastExpr *CE) {
1997 if (CE->getCastKind() != CK_LValueToRValue)
1998 return;
1999 checkAccess(CE->getSubExpr(), AK_Read);
2000}
2001
2002void 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
2032void 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[[clang::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
2094void 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
2104static CXXConstructorDecl *
2105findConstructorForByValueReturn(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
2122static 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
2131void 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
2185void 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.
2234static 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.
2253void 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.
2549void threadSafety::runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2550 ThreadSafetyHandler &Handler,
2551 BeforeSet **BSet) {
2552 if (!*BSet)
1
Assuming the condition is false
2
Taking false branch
2553 *BSet = new BeforeSet;
2554 ThreadSafetyAnalyzer Analyzer(Handler, *BSet);
3
Calling constructor for 'ThreadSafetyAnalyzer'
2555 Analyzer.runAnalysis(AC);
2556}
2557
2558void threadSafety::threadSafetyCleanup(BeforeSet *Cache) { delete Cache; }
2559
2560/// Helper function that returns a LockKind required for the given level
2561/// of access.
2562LockKind 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")::llvm::llvm_unreachable_internal("Unknown AccessKind", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/Analysis/ThreadSafety.cpp"
, 2569)
;
2570}

/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/include/clang/Analysis/Analyses/ThreadSafetyCommon.h

1//===- ThreadSafetyCommon.h -------------------------------------*- C++ -*-===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Parts of thread safety analysis that are not specific to thread safety
11// itself have been factored into classes here, where they can be potentially
12// used by other analyses. Currently these include:
13//
14// * Generalize clang CFG visitors.
15// * Conversion of the clang CFG to SSA form.
16// * Translation of clang Exprs to TIL SExprs
17//
18// UNDER CONSTRUCTION. USE AT YOUR OWN RISK.
19//
20//===----------------------------------------------------------------------===//
21
22#ifndef LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYCOMMON_H
23#define LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYCOMMON_H
24
25#include "clang/AST/Decl.h"
26#include "clang/Analysis/Analyses/PostOrderCFGView.h"
27#include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
28#include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
29#include "clang/Analysis/Analyses/ThreadSafetyUtil.h"
30#include "clang/Analysis/AnalysisDeclContext.h"
31#include "clang/Analysis/CFG.h"
32#include "clang/Basic/LLVM.h"
33#include "llvm/ADT/DenseMap.h"
34#include "llvm/ADT/SmallVector.h"
35#include "llvm/Support/Casting.h"
36#include <sstream>
37#include <string>
38#include <utility>
39#include <vector>
40
41namespace clang {
42
43class AbstractConditionalOperator;
44class ArraySubscriptExpr;
45class BinaryOperator;
46class CallExpr;
47class CastExpr;
48class CXXDestructorDecl;
49class CXXMemberCallExpr;
50class CXXOperatorCallExpr;
51class CXXThisExpr;
52class DeclRefExpr;
53class DeclStmt;
54class Expr;
55class MemberExpr;
56class Stmt;
57class UnaryOperator;
58
59namespace threadSafety {
60
61// Various helper functions on til::SExpr
62namespace sx {
63
64inline bool equals(const til::SExpr *E1, const til::SExpr *E2) {
65 return til::EqualsComparator::compareExprs(E1, E2);
66}
67
68inline bool matches(const til::SExpr *E1, const til::SExpr *E2) {
69 // We treat a top-level wildcard as the "univsersal" lock.
70 // It matches everything for the purpose of checking locks, but not
71 // for unlocking them.
72 if (isa<til::Wildcard>(E1))
73 return isa<til::Wildcard>(E2);
74 if (isa<til::Wildcard>(E2))
75 return isa<til::Wildcard>(E1);
76
77 return til::MatchComparator::compareExprs(E1, E2);
78}
79
80inline bool partiallyMatches(const til::SExpr *E1, const til::SExpr *E2) {
81 const auto *PE1 = dyn_cast_or_null<til::Project>(E1);
82 if (!PE1)
83 return false;
84 const auto *PE2 = dyn_cast_or_null<til::Project>(E2);
85 if (!PE2)
86 return false;
87 return PE1->clangDecl() == PE2->clangDecl();
88}
89
90inline std::string toString(const til::SExpr *E) {
91 std::stringstream ss;
92 til::StdPrinter::print(E, ss);
93 return ss.str();
94}
95
96} // namespace sx
97
98// This class defines the interface of a clang CFG Visitor.
99// CFGWalker will invoke the following methods.
100// Note that methods are not virtual; the visitor is templatized.
101class CFGVisitor {
102 // Enter the CFG for Decl D, and perform any initial setup operations.
103 void enterCFG(CFG *Cfg, const NamedDecl *D, const CFGBlock *First) {}
104
105 // Enter a CFGBlock.
106 void enterCFGBlock(const CFGBlock *B) {}
107
108 // Returns true if this visitor implements handlePredecessor
109 bool visitPredecessors() { return true; }
110
111 // Process a predecessor edge.
112 void handlePredecessor(const CFGBlock *Pred) {}
113
114 // Process a successor back edge to a previously visited block.
115 void handlePredecessorBackEdge(const CFGBlock *Pred) {}
116
117 // Called just before processing statements.
118 void enterCFGBlockBody(const CFGBlock *B) {}
119
120 // Process an ordinary statement.
121 void handleStatement(const Stmt *S) {}
122
123 // Process a destructor call
124 void handleDestructorCall(const VarDecl *VD, const CXXDestructorDecl *DD) {}
125
126 // Called after all statements have been handled.
127 void exitCFGBlockBody(const CFGBlock *B) {}
128
129 // Return true
130 bool visitSuccessors() { return true; }
131
132 // Process a successor edge.
133 void handleSuccessor(const CFGBlock *Succ) {}
134
135 // Process a successor back edge to a previously visited block.
136 void handleSuccessorBackEdge(const CFGBlock *Succ) {}
137
138 // Leave a CFGBlock.
139 void exitCFGBlock(const CFGBlock *B) {}
140
141 // Leave the CFG, and perform any final cleanup operations.
142 void exitCFG(const CFGBlock *Last) {}
143};
144
145// Walks the clang CFG, and invokes methods on a given CFGVisitor.
146class CFGWalker {
147public:
148 CFGWalker() = default;
149
150 // Initialize the CFGWalker. This setup only needs to be done once, even
151 // if there are multiple passes over the CFG.
152 bool init(AnalysisDeclContext &AC) {
153 ACtx = &AC;
154 CFGraph = AC.getCFG();
155 if (!CFGraph)
156 return false;
157
158 // Ignore anonymous functions.
159 if (!dyn_cast_or_null<NamedDecl>(AC.getDecl()))
160 return false;
161
162 SortedGraph = AC.getAnalysis<PostOrderCFGView>();
163 if (!SortedGraph)
164 return false;
165
166 return true;
167 }
168
169 // Traverse the CFG, calling methods on V as appropriate.
170 template <class Visitor>
171 void walk(Visitor &V) {
172 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
173
174 V.enterCFG(CFGraph, getDecl(), &CFGraph->getEntry());
175
176 for (const auto *CurrBlock : *SortedGraph) {
177 VisitedBlocks.insert(CurrBlock);
178
179 V.enterCFGBlock(CurrBlock);
180
181 // Process predecessors, handling back edges last
182 if (V.visitPredecessors()) {
183 SmallVector<CFGBlock*, 4> BackEdges;
184 // Process successors
185 for (CFGBlock::const_pred_iterator SI = CurrBlock->pred_begin(),
186 SE = CurrBlock->pred_end();
187 SI != SE; ++SI) {
188 if (*SI == nullptr)
189 continue;
190
191 if (!VisitedBlocks.alreadySet(*SI)) {
192 BackEdges.push_back(*SI);
193 continue;
194 }
195 V.handlePredecessor(*SI);
196 }
197
198 for (auto *Blk : BackEdges)
199 V.handlePredecessorBackEdge(Blk);
200 }
201
202 V.enterCFGBlockBody(CurrBlock);
203
204 // Process statements
205 for (const auto &BI : *CurrBlock) {
206 switch (BI.getKind()) {
207 case CFGElement::Statement:
208 V.handleStatement(BI.castAs<CFGStmt>().getStmt());
209 break;
210
211 case CFGElement::AutomaticObjectDtor: {
212 CFGAutomaticObjDtor AD = BI.castAs<CFGAutomaticObjDtor>();
213 auto *DD = const_cast<CXXDestructorDecl *>(
214 AD.getDestructorDecl(ACtx->getASTContext()));
215 auto *VD = const_cast<VarDecl *>(AD.getVarDecl());
216 V.handleDestructorCall(VD, DD);
217 break;
218 }
219 default:
220 break;
221 }
222 }
223
224 V.exitCFGBlockBody(CurrBlock);
225
226 // Process successors, handling back edges first.
227 if (V.visitSuccessors()) {
228 SmallVector<CFGBlock*, 8> ForwardEdges;
229
230 // Process successors
231 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
232 SE = CurrBlock->succ_end();
233 SI != SE; ++SI) {
234 if (*SI == nullptr)
235 continue;
236
237 if (!VisitedBlocks.alreadySet(*SI)) {
238 ForwardEdges.push_back(*SI);
239 continue;
240 }
241 V.handleSuccessorBackEdge(*SI);
242 }
243
244 for (auto *Blk : ForwardEdges)
245 V.handleSuccessor(Blk);
246 }
247
248 V.exitCFGBlock(CurrBlock);
249 }
250 V.exitCFG(&CFGraph->getExit());
251 }
252
253 const CFG *getGraph() const { return CFGraph; }
254 CFG *getGraph() { return CFGraph; }
255
256 const NamedDecl *getDecl() const {
257 return dyn_cast<NamedDecl>(ACtx->getDecl());
258 }
259
260 const PostOrderCFGView *getSortedGraph() const { return SortedGraph; }
261
262private:
263 CFG *CFGraph = nullptr;
264 AnalysisDeclContext *ACtx = nullptr;
265 PostOrderCFGView *SortedGraph = nullptr;
266};
267
268// TODO: move this back into ThreadSafety.cpp
269// This is specific to thread safety. It is here because
270// translateAttrExpr needs it, but that should be moved too.
271class CapabilityExpr {
272private:
273 /// The capability expression.
274 const til::SExpr* CapExpr;
275
276 /// True if this is a negative capability.
277 bool Negated;
278
279public:
280 CapabilityExpr(const til::SExpr *E, bool Neg) : CapExpr(E), Negated(Neg) {}
281
282 const til::SExpr* sexpr() const { return CapExpr; }
283 bool negative() const { return Negated; }
284
285 CapabilityExpr operator!() const {
286 return CapabilityExpr(CapExpr, !Negated);
287 }
288
289 bool equals(const CapabilityExpr &other) const {
290 return (Negated == other.Negated) && sx::equals(CapExpr, other.CapExpr);
291 }
292
293 bool matches(const CapabilityExpr &other) const {
294 return (Negated == other.Negated) && sx::matches(CapExpr, other.CapExpr);
295 }
296
297 bool matchesUniv(const CapabilityExpr &CapE) const {
298 return isUniversal() || matches(CapE);
299 }
300
301 bool partiallyMatches(const CapabilityExpr &other) const {
302 return (Negated == other.Negated) &&
303 sx::partiallyMatches(CapExpr, other.CapExpr);
304 }
305
306 const ValueDecl* valueDecl() const {
307 if (Negated || CapExpr == nullptr)
308 return nullptr;
309 if (const auto *P = dyn_cast<til::Project>(CapExpr))
310 return P->clangDecl();
311 if (const auto *P = dyn_cast<til::LiteralPtr>(CapExpr))
312 return P->clangDecl();
313 return nullptr;
314 }
315
316 std::string toString() const {
317 if (Negated)
318 return "!" + sx::toString(CapExpr);
319 return sx::toString(CapExpr);
320 }
321
322 bool shouldIgnore() const { return CapExpr == nullptr; }
323
324 bool isInvalid() const { return sexpr() && isa<til::Undefined>(sexpr()); }
325
326 bool isUniversal() const { return sexpr() && isa<til::Wildcard>(sexpr()); }
327};
328
329// Translate clang::Expr to til::SExpr.
330class SExprBuilder {
331public:
332 /// Encapsulates the lexical context of a function call. The lexical
333 /// context includes the arguments to the call, including the implicit object
334 /// argument. When an attribute containing a mutex expression is attached to
335 /// a method, the expression may refer to formal parameters of the method.
336 /// Actual arguments must be substituted for formal parameters to derive
337 /// the appropriate mutex expression in the lexical context where the function
338 /// is called. PrevCtx holds the context in which the arguments themselves
339 /// should be evaluated; multiple calling contexts can be chained together
340 /// by the lock_returned attribute.
341 struct CallingContext {
342 // The previous context; or 0 if none.
343 CallingContext *Prev;
344
345 // The decl to which the attr is attached.
346 const NamedDecl *AttrDecl;
347
348 // Implicit object argument -- e.g. 'this'
349 const Expr *SelfArg = nullptr;
350
351 // Number of funArgs
352 unsigned NumArgs = 0;
353
354 // Function arguments
355 const Expr *const *FunArgs = nullptr;
356
357 // is Self referred to with -> or .?
358 bool SelfArrow = false;
359
360 CallingContext(CallingContext *P, const NamedDecl *D = nullptr)
361 : Prev(P), AttrDecl(D) {}
362 };
363
364 SExprBuilder(til::MemRegionRef A) : Arena(A) {
365 // FIXME: we don't always have a self-variable.
366 SelfVar = new (Arena) til::Variable(nullptr);
5
Null pointer value stored to 'Analyzer.SxBuilder.SelfVar'
367 SelfVar->setKind(til::Variable::VK_SFun);
6
Called C++ object pointer is null
368 }
369
370 // Translate a clang expression in an attribute to a til::SExpr.
371 // Constructs the context from D, DeclExp, and SelfDecl.
372 CapabilityExpr translateAttrExpr(const Expr *AttrExp, const NamedDecl *D,
373 const Expr *DeclExp, VarDecl *SelfD=nullptr);
374
375 CapabilityExpr translateAttrExpr(const Expr *AttrExp, CallingContext *Ctx);
376
377 // Translate a clang statement or expression to a TIL expression.
378 // Also performs substitution of variables; Ctx provides the context.
379 // Dispatches on the type of S.
380 til::SExpr *translate(const Stmt *S, CallingContext *Ctx);
381 til::SCFG *buildCFG(CFGWalker &Walker);
382
383 til::SExpr *lookupStmt(const Stmt *S);
384
385 til::BasicBlock *lookupBlock(const CFGBlock *B) {
386 return BlockMap[B->getBlockID()];
387 }
388
389 const til::SCFG *getCFG() const { return Scfg; }
390 til::SCFG *getCFG() { return Scfg; }
391
392private:
393 // We implement the CFGVisitor API
394 friend class CFGWalker;
395
396 til::SExpr *translateDeclRefExpr(const DeclRefExpr *DRE,
397 CallingContext *Ctx) ;
398 til::SExpr *translateCXXThisExpr(const CXXThisExpr *TE, CallingContext *Ctx);
399 til::SExpr *translateMemberExpr(const MemberExpr *ME, CallingContext *Ctx);
400 til::SExpr *translateObjCIVarRefExpr(const ObjCIvarRefExpr *IVRE,
401 CallingContext *Ctx);
402 til::SExpr *translateCallExpr(const CallExpr *CE, CallingContext *Ctx,
403 const Expr *SelfE = nullptr);
404 til::SExpr *translateCXXMemberCallExpr(const CXXMemberCallExpr *ME,
405 CallingContext *Ctx);
406 til::SExpr *translateCXXOperatorCallExpr(const CXXOperatorCallExpr *OCE,
407 CallingContext *Ctx);
408 til::SExpr *translateUnaryOperator(const UnaryOperator *UO,
409 CallingContext *Ctx);
410 til::SExpr *translateBinOp(til::TIL_BinaryOpcode Op,
411 const BinaryOperator *BO,
412 CallingContext *Ctx, bool Reverse = false);
413 til::SExpr *translateBinAssign(til::TIL_BinaryOpcode Op,
414 const BinaryOperator *BO,
415 CallingContext *Ctx, bool Assign = false);
416 til::SExpr *translateBinaryOperator(const BinaryOperator *BO,
417 CallingContext *Ctx);
418 til::SExpr *translateCastExpr(const CastExpr *CE, CallingContext *Ctx);
419 til::SExpr *translateArraySubscriptExpr(const ArraySubscriptExpr *E,
420 CallingContext *Ctx);
421 til::SExpr *translateAbstractConditionalOperator(
422 const AbstractConditionalOperator *C, CallingContext *Ctx);
423
424 til::SExpr *translateDeclStmt(const DeclStmt *S, CallingContext *Ctx);
425
426 // Map from statements in the clang CFG to SExprs in the til::SCFG.
427 using StatementMap = llvm::DenseMap<const Stmt *, til::SExpr *>;
428
429 // Map from clang local variables to indices in a LVarDefinitionMap.
430 using LVarIndexMap = llvm::DenseMap<const ValueDecl *, unsigned>;
431
432 // Map from local variable indices to SSA variables (or constants).
433 using NameVarPair = std::pair<const ValueDecl *, til::SExpr *>;
434 using LVarDefinitionMap = CopyOnWriteVector<NameVarPair>;
435
436 struct BlockInfo {
437 LVarDefinitionMap ExitMap;
438 bool HasBackEdges = false;
439
440 // Successors yet to be processed
441 unsigned UnprocessedSuccessors = 0;
442
443 // Predecessors already processed
444 unsigned ProcessedPredecessors = 0;
445
446 BlockInfo() = default;
447 BlockInfo(BlockInfo &&) = default;
448 BlockInfo &operator=(BlockInfo &&) = default;
449 };
450
451 void enterCFG(CFG *Cfg, const NamedDecl *D, const CFGBlock *First);
452 void enterCFGBlock(const CFGBlock *B);
453 bool visitPredecessors() { return true; }
454 void handlePredecessor(const CFGBlock *Pred);
455 void handlePredecessorBackEdge(const CFGBlock *Pred);
456 void enterCFGBlockBody(const CFGBlock *B);
457 void handleStatement(const Stmt *S);
458 void handleDestructorCall(const VarDecl *VD, const CXXDestructorDecl *DD);
459 void exitCFGBlockBody(const CFGBlock *B);
460 bool visitSuccessors() { return true; }
461 void handleSuccessor(const CFGBlock *Succ);
462 void handleSuccessorBackEdge(const CFGBlock *Succ);
463 void exitCFGBlock(const CFGBlock *B);
464 void exitCFG(const CFGBlock *Last);
465
466 void insertStmt(const Stmt *S, til::SExpr *E) {
467 SMap.insert(std::make_pair(S, E));
468 }
469
470 til::SExpr *getCurrentLVarDefinition(const ValueDecl *VD);
471
472 til::SExpr *addStatement(til::SExpr *E, const Stmt *S,
473 const ValueDecl *VD = nullptr);
474 til::SExpr *lookupVarDecl(const ValueDecl *VD);
475 til::SExpr *addVarDecl(const ValueDecl *VD, til::SExpr *E);
476 til::SExpr *updateVarDecl(const ValueDecl *VD, til::SExpr *E);
477
478 void makePhiNodeVar(unsigned i, unsigned NPreds, til::SExpr *E);
479 void mergeEntryMap(LVarDefinitionMap Map);
480 void mergeEntryMapBackEdge();
481 void mergePhiNodesBackEdge(const CFGBlock *Blk);
482
483private:
484 // Set to true when parsing capability expressions, which get translated
485 // inaccurately in order to hack around smart pointers etc.
486 static const bool CapabilityExprMode = true;
487
488 til::MemRegionRef Arena;
489
490 // Variable to use for 'this'. May be null.
491 til::Variable *SelfVar = nullptr;
492
493 til::SCFG *Scfg = nullptr;
494
495 // Map from Stmt to TIL Variables
496 StatementMap SMap;
497
498 // Indices of clang local vars.
499 LVarIndexMap LVarIdxMap;
500
501 // Map from clang to til BBs.
502 std::vector<til::BasicBlock *> BlockMap;
503
504 // Extra information per BB. Indexed by clang BlockID.
505 std::vector<BlockInfo> BBInfo;
506
507 LVarDefinitionMap CurrentLVarMap;
508 std::vector<til::Phi *> CurrentArguments;
509 std::vector<til::SExpr *> CurrentInstructions;
510 std::vector<til::Phi *> IncompleteArgs;
511 til::BasicBlock *CurrentBB = nullptr;
512 BlockInfo *CurrentBlockInfo = nullptr;
513};
514
515// Dump an SCFG to llvm::errs().
516void printSCFG(CFGWalker &Walker);
517
518} // namespace threadSafety
519} // namespace clang
520
521#endif // LLVM_CLANG_THREAD_SAFETY_COMMON_H