1 //===- ThreadSafety.cpp ----------------------------------------*- C++ --*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // A intra-procedural analysis for thread safety (e.g. deadlocks and race
11 // conditions), based off of an annotation system.
13 // See http://clang.llvm.org/docs/LanguageExtensions.html#threadsafety for more
16 //===----------------------------------------------------------------------===//
18 #include "clang/Analysis/Analyses/ThreadSafety.h"
19 #include "clang/Analysis/Analyses/PostOrderCFGView.h"
20 #include "clang/Analysis/AnalysisContext.h"
21 #include "clang/Analysis/CFG.h"
22 #include "clang/Analysis/CFGStmtMap.h"
23 #include "clang/AST/DeclCXX.h"
24 #include "clang/AST/ExprCXX.h"
25 #include "clang/AST/StmtCXX.h"
26 #include "clang/AST/StmtVisitor.h"
27 #include "clang/Basic/SourceManager.h"
28 #include "clang/Basic/SourceLocation.h"
29 #include "clang/Basic/OperatorKinds.h"
30 #include "llvm/ADT/BitVector.h"
31 #include "llvm/ADT/FoldingSet.h"
32 #include "llvm/ADT/ImmutableMap.h"
33 #include "llvm/ADT/PostOrderIterator.h"
34 #include "llvm/ADT/SmallVector.h"
35 #include "llvm/ADT/StringRef.h"
36 #include "llvm/Support/raw_ostream.h"
41 using namespace clang;
42 using namespace thread_safety;
44 // Key method definition
45 ThreadSafetyHandler::~ThreadSafetyHandler() {}
49 /// SExpr implements a simple expression language that is used to store,
50 /// compare, and pretty-print C++ expressions. Unlike a clang Expr, a SExpr
51 /// does not capture surface syntax, and it does not distinguish between
52 /// C++ concepts, like pointers and references, that have no real semantic
53 /// differences. This simplicity allows SExprs to be meaningfully compared,
56 /// (*this).foo = this->foo
59 /// Thread-safety analysis works by comparing lock expressions. Within the
60 /// body of a function, an expression such as "x->foo->bar.mu" will resolve to
61 /// a particular mutex object at run-time. Subsequent occurrences of the same
62 /// expression (where "same" means syntactic equality) will refer to the same
63 /// run-time object if three conditions hold:
64 /// (1) Local variables in the expression, such as "x" have not changed.
65 /// (2) Values on the heap that affect the expression have not changed.
66 /// (3) The expression involves only pure function calls.
68 /// The current implementation assumes, but does not verify, that multiple uses
69 /// of the same lock expression satisfies these criteria.
74 EOP_Wildcard, ///< Matches anything.
75 EOP_Universal, ///< Universal lock.
76 EOP_This, ///< This keyword.
77 EOP_NVar, ///< Named variable.
78 EOP_LVar, ///< Local variable.
79 EOP_Dot, ///< Field access
80 EOP_Call, ///< Function call
81 EOP_MCall, ///< Method call
82 EOP_Index, ///< Array index
83 EOP_Unary, ///< Unary operation
84 EOP_Binary, ///< Binary operation
85 EOP_Unknown ///< Catchall for everything else
91 unsigned char Op; ///< Opcode of the root node
92 unsigned char Flags; ///< Additional opcode-specific data
93 unsigned short Sz; ///< Number of child nodes
94 const void* Data; ///< Additional opcode-specific data
97 SExprNode(ExprOp O, unsigned F, const void* D)
98 : Op(static_cast<unsigned char>(O)),
99 Flags(static_cast<unsigned char>(F)), Sz(1), Data(D)
102 unsigned size() const { return Sz; }
103 void setSize(unsigned S) { Sz = S; }
105 ExprOp kind() const { return static_cast<ExprOp>(Op); }
107 const NamedDecl* getNamedDecl() const {
108 assert(Op == EOP_NVar || Op == EOP_LVar || Op == EOP_Dot);
109 return reinterpret_cast<const NamedDecl*>(Data);
112 const NamedDecl* getFunctionDecl() const {
113 assert(Op == EOP_Call || Op == EOP_MCall);
114 return reinterpret_cast<const NamedDecl*>(Data);
117 bool isArrow() const { return Op == EOP_Dot && Flags == 1; }
118 void setArrow(bool A) { Flags = A ? 1 : 0; }
120 unsigned arity() const {
122 case EOP_Nop: return 0;
123 case EOP_Wildcard: return 0;
124 case EOP_Universal: return 0;
125 case EOP_NVar: return 0;
126 case EOP_LVar: return 0;
127 case EOP_This: return 0;
128 case EOP_Dot: return 1;
129 case EOP_Call: return Flags+1; // First arg is function.
130 case EOP_MCall: return Flags+1; // First arg is implicit obj.
131 case EOP_Index: return 2;
132 case EOP_Unary: return 1;
133 case EOP_Binary: return 2;
134 case EOP_Unknown: return Flags;
139 bool operator==(const SExprNode& Other) const {
140 // Ignore flags and size -- they don't matter.
141 return (Op == Other.Op &&
145 bool operator!=(const SExprNode& Other) const {
146 return !(*this == Other);
149 bool matches(const SExprNode& Other) const {
150 return (*this == Other) ||
151 (Op == EOP_Wildcard) ||
152 (Other.Op == EOP_Wildcard);
157 /// \brief Encapsulates the lexical context of a function call. The lexical
158 /// context includes the arguments to the call, including the implicit object
159 /// argument. When an attribute containing a mutex expression is attached to
160 /// a method, the expression may refer to formal parameters of the method.
161 /// Actual arguments must be substituted for formal parameters to derive
162 /// the appropriate mutex expression in the lexical context where the function
163 /// is called. PrevCtx holds the context in which the arguments themselves
164 /// should be evaluated; multiple calling contexts can be chained together
165 /// by the lock_returned attribute.
166 struct CallingContext {
167 const NamedDecl* AttrDecl; // The decl to which the attribute is attached.
168 Expr* SelfArg; // Implicit object argument -- e.g. 'this'
169 bool SelfArrow; // is Self referred to with -> or .?
170 unsigned NumArgs; // Number of funArgs
171 Expr** FunArgs; // Function arguments
172 CallingContext* PrevCtx; // The previous context; or 0 if none.
174 CallingContext(const NamedDecl *D = 0, Expr *S = 0,
175 unsigned N = 0, Expr **A = 0, CallingContext *P = 0)
176 : AttrDecl(D), SelfArg(S), SelfArrow(false),
177 NumArgs(N), FunArgs(A), PrevCtx(P)
181 typedef SmallVector<SExprNode, 4> NodeVector;
184 // A SExpr is a list of SExprNodes in prefix order. The Size field allows
185 // the list to be traversed as a tree.
190 NodeVec.push_back(SExprNode(EOP_Nop, 0, 0));
191 return NodeVec.size()-1;
194 unsigned makeWildcard() {
195 NodeVec.push_back(SExprNode(EOP_Wildcard, 0, 0));
196 return NodeVec.size()-1;
199 unsigned makeUniversal() {
200 NodeVec.push_back(SExprNode(EOP_Universal, 0, 0));
201 return NodeVec.size()-1;
204 unsigned makeNamedVar(const NamedDecl *D) {
205 NodeVec.push_back(SExprNode(EOP_NVar, 0, D));
206 return NodeVec.size()-1;
209 unsigned makeLocalVar(const NamedDecl *D) {
210 NodeVec.push_back(SExprNode(EOP_LVar, 0, D));
211 return NodeVec.size()-1;
214 unsigned makeThis() {
215 NodeVec.push_back(SExprNode(EOP_This, 0, 0));
216 return NodeVec.size()-1;
219 unsigned makeDot(const NamedDecl *D, bool Arrow) {
220 NodeVec.push_back(SExprNode(EOP_Dot, Arrow ? 1 : 0, D));
221 return NodeVec.size()-1;
224 unsigned makeCall(unsigned NumArgs, const NamedDecl *D) {
225 NodeVec.push_back(SExprNode(EOP_Call, NumArgs, D));
226 return NodeVec.size()-1;
229 // Grab the very first declaration of virtual method D
230 const CXXMethodDecl* getFirstVirtualDecl(const CXXMethodDecl *D) {
232 D = D->getCanonicalDecl();
233 CXXMethodDecl::method_iterator I = D->begin_overridden_methods(),
234 E = D->end_overridden_methods();
236 return D; // Method does not override anything
237 D = *I; // FIXME: this does not work with multiple inheritance.
242 unsigned makeMCall(unsigned NumArgs, const CXXMethodDecl *D) {
243 NodeVec.push_back(SExprNode(EOP_MCall, NumArgs, getFirstVirtualDecl(D)));
244 return NodeVec.size()-1;
247 unsigned makeIndex() {
248 NodeVec.push_back(SExprNode(EOP_Index, 0, 0));
249 return NodeVec.size()-1;
252 unsigned makeUnary() {
253 NodeVec.push_back(SExprNode(EOP_Unary, 0, 0));
254 return NodeVec.size()-1;
257 unsigned makeBinary() {
258 NodeVec.push_back(SExprNode(EOP_Binary, 0, 0));
259 return NodeVec.size()-1;
262 unsigned makeUnknown(unsigned Arity) {
263 NodeVec.push_back(SExprNode(EOP_Unknown, Arity, 0));
264 return NodeVec.size()-1;
267 /// Build an SExpr from the given C++ expression.
268 /// Recursive function that terminates on DeclRefExpr.
269 /// Note: this function merely creates a SExpr; it does not check to
270 /// ensure that the original expression is a valid mutex expression.
272 /// NDeref returns the number of Derefence and AddressOf operations
273 /// preceeding the Expr; this is used to decide whether to pretty-print
274 /// SExprs with . or ->.
275 unsigned buildSExpr(Expr *Exp, CallingContext* CallCtx, int* NDeref = 0) {
279 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Exp)) {
280 NamedDecl *ND = cast<NamedDecl>(DRE->getDecl()->getCanonicalDecl());
281 ParmVarDecl *PV = dyn_cast_or_null<ParmVarDecl>(ND);
284 cast<FunctionDecl>(PV->getDeclContext())->getCanonicalDecl();
285 unsigned i = PV->getFunctionScopeIndex();
287 if (CallCtx && CallCtx->FunArgs &&
288 FD == CallCtx->AttrDecl->getCanonicalDecl()) {
289 // Substitute call arguments for references to function parameters
290 assert(i < CallCtx->NumArgs);
291 return buildSExpr(CallCtx->FunArgs[i], CallCtx->PrevCtx, NDeref);
293 // Map the param back to the param of the original function declaration.
294 makeNamedVar(FD->getParamDecl(i));
297 // Not a function parameter -- just store the reference.
300 } else if (isa<CXXThisExpr>(Exp)) {
301 // Substitute parent for 'this'
302 if (CallCtx && CallCtx->SelfArg) {
303 if (!CallCtx->SelfArrow && NDeref)
304 // 'this' is a pointer, but self is not, so need to take address.
306 return buildSExpr(CallCtx->SelfArg, CallCtx->PrevCtx, NDeref);
312 } else if (MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
313 NamedDecl *ND = ME->getMemberDecl();
314 int ImplicitDeref = ME->isArrow() ? 1 : 0;
315 unsigned Root = makeDot(ND, false);
316 unsigned Sz = buildSExpr(ME->getBase(), CallCtx, &ImplicitDeref);
317 NodeVec[Root].setArrow(ImplicitDeref > 0);
318 NodeVec[Root].setSize(Sz + 1);
320 } else if (CXXMemberCallExpr *CMCE = dyn_cast<CXXMemberCallExpr>(Exp)) {
321 // When calling a function with a lock_returned attribute, replace
322 // the function call with the expression in lock_returned.
324 cast<CXXMethodDecl>(CMCE->getMethodDecl()->getMostRecentDecl());
325 if (LockReturnedAttr* At = MD->getAttr<LockReturnedAttr>()) {
326 CallingContext LRCallCtx(CMCE->getMethodDecl());
327 LRCallCtx.SelfArg = CMCE->getImplicitObjectArgument();
328 LRCallCtx.SelfArrow =
329 dyn_cast<MemberExpr>(CMCE->getCallee())->isArrow();
330 LRCallCtx.NumArgs = CMCE->getNumArgs();
331 LRCallCtx.FunArgs = CMCE->getArgs();
332 LRCallCtx.PrevCtx = CallCtx;
333 return buildSExpr(At->getArg(), &LRCallCtx);
335 // Hack to treat smart pointers and iterators as pointers;
336 // ignore any method named get().
337 if (CMCE->getMethodDecl()->getNameAsString() == "get" &&
338 CMCE->getNumArgs() == 0) {
339 if (NDeref && dyn_cast<MemberExpr>(CMCE->getCallee())->isArrow())
341 return buildSExpr(CMCE->getImplicitObjectArgument(), CallCtx, NDeref);
343 unsigned NumCallArgs = CMCE->getNumArgs();
344 unsigned Root = makeMCall(NumCallArgs, CMCE->getMethodDecl());
345 unsigned Sz = buildSExpr(CMCE->getImplicitObjectArgument(), CallCtx);
346 Expr** CallArgs = CMCE->getArgs();
347 for (unsigned i = 0; i < NumCallArgs; ++i) {
348 Sz += buildSExpr(CallArgs[i], CallCtx);
350 NodeVec[Root].setSize(Sz + 1);
352 } else if (CallExpr *CE = dyn_cast<CallExpr>(Exp)) {
354 cast<FunctionDecl>(CE->getDirectCallee()->getMostRecentDecl());
355 if (LockReturnedAttr* At = FD->getAttr<LockReturnedAttr>()) {
356 CallingContext LRCallCtx(CE->getDirectCallee());
357 LRCallCtx.NumArgs = CE->getNumArgs();
358 LRCallCtx.FunArgs = CE->getArgs();
359 LRCallCtx.PrevCtx = CallCtx;
360 return buildSExpr(At->getArg(), &LRCallCtx);
362 // Treat smart pointers and iterators as pointers;
363 // ignore the * and -> operators.
364 if (CXXOperatorCallExpr *OE = dyn_cast<CXXOperatorCallExpr>(CE)) {
365 OverloadedOperatorKind k = OE->getOperator();
367 if (NDeref) ++(*NDeref);
368 return buildSExpr(OE->getArg(0), CallCtx, NDeref);
370 else if (k == OO_Arrow) {
371 return buildSExpr(OE->getArg(0), CallCtx, NDeref);
374 unsigned NumCallArgs = CE->getNumArgs();
375 unsigned Root = makeCall(NumCallArgs, 0);
376 unsigned Sz = buildSExpr(CE->getCallee(), CallCtx);
377 Expr** CallArgs = CE->getArgs();
378 for (unsigned i = 0; i < NumCallArgs; ++i) {
379 Sz += buildSExpr(CallArgs[i], CallCtx);
381 NodeVec[Root].setSize(Sz+1);
383 } else if (BinaryOperator *BOE = dyn_cast<BinaryOperator>(Exp)) {
384 unsigned Root = makeBinary();
385 unsigned Sz = buildSExpr(BOE->getLHS(), CallCtx);
386 Sz += buildSExpr(BOE->getRHS(), CallCtx);
387 NodeVec[Root].setSize(Sz);
389 } else if (UnaryOperator *UOE = dyn_cast<UnaryOperator>(Exp)) {
390 // Ignore & and * operators -- they're no-ops.
391 // However, we try to figure out whether the expression is a pointer,
392 // so we can use . and -> appropriately in error messages.
393 if (UOE->getOpcode() == UO_Deref) {
394 if (NDeref) ++(*NDeref);
395 return buildSExpr(UOE->getSubExpr(), CallCtx, NDeref);
397 if (UOE->getOpcode() == UO_AddrOf) {
398 if (DeclRefExpr* DRE = dyn_cast<DeclRefExpr>(UOE->getSubExpr())) {
399 if (DRE->getDecl()->isCXXInstanceMember()) {
400 // This is a pointer-to-member expression, e.g. &MyClass::mu_.
401 // We interpret this syntax specially, as a wildcard.
402 unsigned Root = makeDot(DRE->getDecl(), false);
404 NodeVec[Root].setSize(2);
408 if (NDeref) --(*NDeref);
409 return buildSExpr(UOE->getSubExpr(), CallCtx, NDeref);
411 unsigned Root = makeUnary();
412 unsigned Sz = buildSExpr(UOE->getSubExpr(), CallCtx);
413 NodeVec[Root].setSize(Sz);
415 } else if (ArraySubscriptExpr *ASE = dyn_cast<ArraySubscriptExpr>(Exp)) {
416 unsigned Root = makeIndex();
417 unsigned Sz = buildSExpr(ASE->getBase(), CallCtx);
418 Sz += buildSExpr(ASE->getIdx(), CallCtx);
419 NodeVec[Root].setSize(Sz);
421 } else if (AbstractConditionalOperator *CE =
422 dyn_cast<AbstractConditionalOperator>(Exp)) {
423 unsigned Root = makeUnknown(3);
424 unsigned Sz = buildSExpr(CE->getCond(), CallCtx);
425 Sz += buildSExpr(CE->getTrueExpr(), CallCtx);
426 Sz += buildSExpr(CE->getFalseExpr(), CallCtx);
427 NodeVec[Root].setSize(Sz);
429 } else if (ChooseExpr *CE = dyn_cast<ChooseExpr>(Exp)) {
430 unsigned Root = makeUnknown(3);
431 unsigned Sz = buildSExpr(CE->getCond(), CallCtx);
432 Sz += buildSExpr(CE->getLHS(), CallCtx);
433 Sz += buildSExpr(CE->getRHS(), CallCtx);
434 NodeVec[Root].setSize(Sz);
436 } else if (CastExpr *CE = dyn_cast<CastExpr>(Exp)) {
437 return buildSExpr(CE->getSubExpr(), CallCtx, NDeref);
438 } else if (ParenExpr *PE = dyn_cast<ParenExpr>(Exp)) {
439 return buildSExpr(PE->getSubExpr(), CallCtx, NDeref);
440 } else if (ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Exp)) {
441 return buildSExpr(EWC->getSubExpr(), CallCtx, NDeref);
442 } else if (CXXBindTemporaryExpr *E = dyn_cast<CXXBindTemporaryExpr>(Exp)) {
443 return buildSExpr(E->getSubExpr(), CallCtx, NDeref);
444 } else if (isa<CharacterLiteral>(Exp) ||
445 isa<CXXNullPtrLiteralExpr>(Exp) ||
446 isa<GNUNullExpr>(Exp) ||
447 isa<CXXBoolLiteralExpr>(Exp) ||
448 isa<FloatingLiteral>(Exp) ||
449 isa<ImaginaryLiteral>(Exp) ||
450 isa<IntegerLiteral>(Exp) ||
451 isa<StringLiteral>(Exp) ||
452 isa<ObjCStringLiteral>(Exp)) {
454 return 1; // FIXME: Ignore literals for now
457 return 1; // Ignore. FIXME: mark as invalid expression?
461 /// \brief Construct a SExpr from an expression.
462 /// \param MutexExp The original mutex expression within an attribute
463 /// \param DeclExp An expression involving the Decl on which the attribute
465 /// \param D The declaration to which the lock/unlock attribute is attached.
466 void buildSExprFromExpr(Expr *MutexExp, Expr *DeclExp, const NamedDecl *D,
467 VarDecl *SelfDecl = 0) {
468 CallingContext CallCtx(D);
471 if (StringLiteral* SLit = dyn_cast<StringLiteral>(MutexExp)) {
472 if (SLit->getString() == StringRef("*"))
473 // The "*" expr is a universal lock, which essentially turns off
474 // checks until it is removed from the lockset.
477 // Ignore other string literals for now.
483 // If we are processing a raw attribute expression, with no substitutions.
485 buildSExpr(MutexExp, 0);
489 // Examine DeclExp to find SelfArg and FunArgs, which are used to substitute
490 // for formal parameters when we call buildMutexID later.
491 if (MemberExpr *ME = dyn_cast<MemberExpr>(DeclExp)) {
492 CallCtx.SelfArg = ME->getBase();
493 CallCtx.SelfArrow = ME->isArrow();
494 } else if (CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(DeclExp)) {
495 CallCtx.SelfArg = CE->getImplicitObjectArgument();
496 CallCtx.SelfArrow = dyn_cast<MemberExpr>(CE->getCallee())->isArrow();
497 CallCtx.NumArgs = CE->getNumArgs();
498 CallCtx.FunArgs = CE->getArgs();
499 } else if (CallExpr *CE = dyn_cast<CallExpr>(DeclExp)) {
500 CallCtx.NumArgs = CE->getNumArgs();
501 CallCtx.FunArgs = CE->getArgs();
502 } else if (CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(DeclExp)) {
503 CallCtx.SelfArg = 0; // Will be set below
504 CallCtx.NumArgs = CE->getNumArgs();
505 CallCtx.FunArgs = CE->getArgs();
506 } else if (D && isa<CXXDestructorDecl>(D)) {
507 // There's no such thing as a "destructor call" in the AST.
508 CallCtx.SelfArg = DeclExp;
511 // Hack to handle constructors, where self cannot be recovered from
513 if (SelfDecl && !CallCtx.SelfArg) {
514 DeclRefExpr SelfDRE(SelfDecl, false, SelfDecl->getType(), VK_LValue,
515 SelfDecl->getLocation());
516 CallCtx.SelfArg = &SelfDRE;
518 // If the attribute has no arguments, then assume the argument is "this".
520 buildSExpr(CallCtx.SelfArg, 0);
521 else // For most attributes.
522 buildSExpr(MutexExp, &CallCtx);
526 // If the attribute has no arguments, then assume the argument is "this".
528 buildSExpr(CallCtx.SelfArg, 0);
529 else // For most attributes.
530 buildSExpr(MutexExp, &CallCtx);
533 /// \brief Get index of next sibling of node i.
534 unsigned getNextSibling(unsigned i) const {
535 return i + NodeVec[i].size();
539 explicit SExpr(clang::Decl::EmptyShell e) { NodeVec.clear(); }
541 /// \param MutexExp The original mutex expression within an attribute
542 /// \param DeclExp An expression involving the Decl on which the attribute
544 /// \param D The declaration to which the lock/unlock attribute is attached.
545 /// Caller must check isValid() after construction.
546 SExpr(Expr* MutexExp, Expr *DeclExp, const NamedDecl* D,
547 VarDecl *SelfDecl=0) {
548 buildSExprFromExpr(MutexExp, DeclExp, D, SelfDecl);
551 /// Return true if this is a valid decl sequence.
552 /// Caller must call this by hand after construction to handle errors.
553 bool isValid() const {
554 return !NodeVec.empty();
557 bool shouldIgnore() const {
558 // Nop is a mutex that we have decided to deliberately ignore.
559 assert(NodeVec.size() > 0 && "Invalid Mutex");
560 return NodeVec[0].kind() == EOP_Nop;
563 bool isUniversal() const {
564 assert(NodeVec.size() > 0 && "Invalid Mutex");
565 return NodeVec[0].kind() == EOP_Universal;
568 /// Issue a warning about an invalid lock expression
569 static void warnInvalidLock(ThreadSafetyHandler &Handler, Expr* MutexExp,
570 Expr *DeclExp, const NamedDecl* D) {
573 Loc = DeclExp->getExprLoc();
575 // FIXME: add a note about the attribute location in MutexExp or D
577 Handler.handleInvalidLockExp(Loc);
580 bool operator==(const SExpr &other) const {
581 return NodeVec == other.NodeVec;
584 bool operator!=(const SExpr &other) const {
585 return !(*this == other);
588 bool matches(const SExpr &Other, unsigned i = 0, unsigned j = 0) const {
589 if (NodeVec[i].matches(Other.NodeVec[j])) {
590 unsigned ni = NodeVec[i].arity();
591 unsigned nj = Other.NodeVec[j].arity();
592 unsigned n = (ni < nj) ? ni : nj;
594 unsigned ci = i+1; // first child of i
595 unsigned cj = j+1; // first child of j
596 for (unsigned k = 0; k < n;
597 ++k, ci=getNextSibling(ci), cj = Other.getNextSibling(cj)) {
598 Result = Result && matches(Other, ci, cj);
605 // A partial match between a.mu and b.mu returns true a and b have the same
606 // type (and thus mu refers to the same mutex declaration), regardless of
607 // whether a and b are different objects or not.
608 bool partiallyMatches(const SExpr &Other) const {
609 if (NodeVec[0].kind() == EOP_Dot)
610 return NodeVec[0].matches(Other.NodeVec[0]);
614 /// \brief Pretty print a lock expression for use in error messages.
615 std::string toString(unsigned i = 0) const {
617 if (i >= NodeVec.size())
620 const SExprNode* N = &NodeVec[i];
632 return N->getNamedDecl()->getNameAsString();
635 if (NodeVec[i+1].kind() == EOP_Wildcard) {
637 S += N->getNamedDecl()->getQualifiedNameAsString();
640 std::string FieldName = N->getNamedDecl()->getNameAsString();
641 if (NodeVec[i+1].kind() == EOP_This)
644 std::string S = toString(i+1);
646 return S + "->" + FieldName;
648 return S + "." + FieldName;
651 std::string S = toString(i+1) + "(";
652 unsigned NumArgs = N->arity()-1;
653 unsigned ci = getNextSibling(i+1);
654 for (unsigned k=0; k<NumArgs; ++k, ci = getNextSibling(ci)) {
656 if (k+1 < NumArgs) S += ",";
663 if (NodeVec[i+1].kind() != EOP_This)
664 S = toString(i+1) + ".";
665 if (const NamedDecl *D = N->getFunctionDecl())
666 S += D->getNameAsString() + "(";
669 unsigned NumArgs = N->arity()-1;
670 unsigned ci = getNextSibling(i+1);
671 for (unsigned k=0; k<NumArgs; ++k, ci = getNextSibling(ci)) {
673 if (k+1 < NumArgs) S += ",";
679 std::string S1 = toString(i+1);
680 std::string S2 = toString(i+1 + NodeVec[i+1].size());
681 return S1 + "[" + S2 + "]";
684 std::string S = toString(i+1);
688 std::string S1 = toString(i+1);
689 std::string S2 = toString(i+1 + NodeVec[i+1].size());
690 return "(" + S1 + "#" + S2 + ")";
693 unsigned NumChildren = N->arity();
694 if (NumChildren == 0)
698 for (unsigned j = 0; j < NumChildren; ++j, ci = getNextSibling(ci)) {
700 if (j+1 < NumChildren) S += "#";
712 /// \brief A short list of SExprs
713 class MutexIDList : public SmallVector<SExpr, 3> {
715 /// \brief Return true if the list contains the specified SExpr
716 /// Performs a linear search, because these lists are almost always very small.
717 bool contains(const SExpr& M) {
718 for (iterator I=begin(),E=end(); I != E; ++I)
719 if ((*I) == M) return true;
723 /// \brief Push M onto list, bud discard duplicates
724 void push_back_nodup(const SExpr& M) {
725 if (!contains(M)) push_back(M);
731 /// \brief This is a helper class that stores info about the most recent
732 /// accquire of a Lock.
734 /// The main body of the analysis maps MutexIDs to LockDatas.
736 SourceLocation AcquireLoc;
738 /// \brief LKind stores whether a lock is held shared or exclusively.
739 /// Note that this analysis does not currently support either re-entrant
740 /// locking or lock "upgrading" and "downgrading" between exclusive and
743 /// FIXME: add support for re-entrant locking and lock up/downgrading
745 bool Managed; // for ScopedLockable objects
746 SExpr UnderlyingMutex; // for ScopedLockable objects
748 LockData(SourceLocation AcquireLoc, LockKind LKind, bool M = false)
749 : AcquireLoc(AcquireLoc), LKind(LKind), Managed(M),
750 UnderlyingMutex(Decl::EmptyShell())
753 LockData(SourceLocation AcquireLoc, LockKind LKind, const SExpr &Mu)
754 : AcquireLoc(AcquireLoc), LKind(LKind), Managed(false),
758 bool operator==(const LockData &other) const {
759 return AcquireLoc == other.AcquireLoc && LKind == other.LKind;
762 bool operator!=(const LockData &other) const {
763 return !(*this == other);
766 void Profile(llvm::FoldingSetNodeID &ID) const {
767 ID.AddInteger(AcquireLoc.getRawEncoding());
768 ID.AddInteger(LKind);
771 bool isAtLeast(LockKind LK) {
772 return (LK == LK_Shared) || (LKind == LK_Exclusive);
777 /// \brief A FactEntry stores a single fact that is known at a particular point
778 /// in the program execution. Currently, this is information regarding a lock
779 /// that is held at that point.
784 FactEntry(const SExpr& M, const LockData& L)
790 typedef unsigned short FactID;
792 /// \brief FactManager manages the memory for all facts that are created during
793 /// the analysis of a single routine.
796 std::vector<FactEntry> Facts;
799 FactID newLock(const SExpr& M, const LockData& L) {
800 Facts.push_back(FactEntry(M,L));
801 return static_cast<unsigned short>(Facts.size() - 1);
804 const FactEntry& operator[](FactID F) const { return Facts[F]; }
805 FactEntry& operator[](FactID F) { return Facts[F]; }
809 /// \brief A FactSet is the set of facts that are known to be true at a
810 /// particular program point. FactSets must be small, because they are
811 /// frequently copied, and are thus implemented as a set of indices into a
812 /// table maintained by a FactManager. A typical FactSet only holds 1 or 2
813 /// locks, so we can get away with doing a linear search for lookup. Note
814 /// that a hashtable or map is inappropriate in this case, because lookups
815 /// may involve partial pattern matches, rather than exact matches.
818 typedef SmallVector<FactID, 4> FactVec;
823 typedef FactVec::iterator iterator;
824 typedef FactVec::const_iterator const_iterator;
826 iterator begin() { return FactIDs.begin(); }
827 const_iterator begin() const { return FactIDs.begin(); }
829 iterator end() { return FactIDs.end(); }
830 const_iterator end() const { return FactIDs.end(); }
832 bool isEmpty() const { return FactIDs.size() == 0; }
834 FactID addLock(FactManager& FM, const SExpr& M, const LockData& L) {
835 FactID F = FM.newLock(M, L);
836 FactIDs.push_back(F);
840 bool removeLock(FactManager& FM, const SExpr& M) {
841 unsigned n = FactIDs.size();
845 for (unsigned i = 0; i < n-1; ++i) {
846 if (FM[FactIDs[i]].MutID.matches(M)) {
847 FactIDs[i] = FactIDs[n-1];
852 if (FM[FactIDs[n-1]].MutID.matches(M)) {
859 LockData* findLock(FactManager &FM, const SExpr &M) const {
860 for (const_iterator I = begin(), E = end(); I != E; ++I) {
861 const SExpr &Exp = FM[*I].MutID;
868 LockData* findLockUniv(FactManager &FM, const SExpr &M) const {
869 for (const_iterator I = begin(), E = end(); I != E; ++I) {
870 const SExpr &Exp = FM[*I].MutID;
871 if (Exp.matches(M) || Exp.isUniversal())
877 FactEntry* findPartialMatch(FactManager &FM, const SExpr &M) const {
878 for (const_iterator I=begin(), E=end(); I != E; ++I) {
879 const SExpr& Exp = FM[*I].MutID;
880 if (Exp.partiallyMatches(M)) return &FM[*I];
888 /// A Lockset maps each SExpr (defined above) to information about how it has
890 typedef llvm::ImmutableMap<SExpr, LockData> Lockset;
891 typedef llvm::ImmutableMap<const NamedDecl*, unsigned> LocalVarContext;
893 class LocalVariableMap;
895 /// A side (entry or exit) of a CFG node.
896 enum CFGBlockSide { CBS_Entry, CBS_Exit };
898 /// CFGBlockInfo is a struct which contains all the information that is
899 /// maintained for each block in the CFG. See LocalVariableMap for more
900 /// information about the contexts.
901 struct CFGBlockInfo {
902 FactSet EntrySet; // Lockset held at entry to block
903 FactSet ExitSet; // Lockset held at exit from block
904 LocalVarContext EntryContext; // Context held at entry to block
905 LocalVarContext ExitContext; // Context held at exit from block
906 SourceLocation EntryLoc; // Location of first statement in block
907 SourceLocation ExitLoc; // Location of last statement in block.
908 unsigned EntryIndex; // Used to replay contexts later
909 bool Reachable; // Is this block reachable?
911 const FactSet &getSet(CFGBlockSide Side) const {
912 return Side == CBS_Entry ? EntrySet : ExitSet;
914 SourceLocation getLocation(CFGBlockSide Side) const {
915 return Side == CBS_Entry ? EntryLoc : ExitLoc;
919 CFGBlockInfo(LocalVarContext EmptyCtx)
920 : EntryContext(EmptyCtx), ExitContext(EmptyCtx), Reachable(false)
924 static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
929 // A LocalVariableMap maintains a map from local variables to their currently
930 // valid definitions. It provides SSA-like functionality when traversing the
931 // CFG. Like SSA, each definition or assignment to a variable is assigned a
932 // unique name (an integer), which acts as the SSA name for that definition.
933 // The total set of names is shared among all CFG basic blocks.
934 // Unlike SSA, we do not rewrite expressions to replace local variables declrefs
935 // with their SSA-names. Instead, we compute a Context for each point in the
936 // code, which maps local variables to the appropriate SSA-name. This map
937 // changes with each assignment.
939 // The map is computed in a single pass over the CFG. Subsequent analyses can
940 // then query the map to find the appropriate Context for a statement, and use
941 // that Context to look up the definitions of variables.
942 class LocalVariableMap {
944 typedef LocalVarContext Context;
946 /// A VarDefinition consists of an expression, representing the value of the
947 /// variable, along with the context in which that expression should be
948 /// interpreted. A reference VarDefinition does not itself contain this
949 /// information, but instead contains a pointer to a previous VarDefinition.
950 struct VarDefinition {
952 friend class LocalVariableMap;
954 const NamedDecl *Dec; // The original declaration for this variable.
955 const Expr *Exp; // The expression for this variable, OR
956 unsigned Ref; // Reference to another VarDefinition
957 Context Ctx; // The map with which Exp should be interpreted.
959 bool isReference() { return !Exp; }
962 // Create ordinary variable definition
963 VarDefinition(const NamedDecl *D, const Expr *E, Context C)
964 : Dec(D), Exp(E), Ref(0), Ctx(C)
967 // Create reference to previous definition
968 VarDefinition(const NamedDecl *D, unsigned R, Context C)
969 : Dec(D), Exp(0), Ref(R), Ctx(C)
974 Context::Factory ContextFactory;
975 std::vector<VarDefinition> VarDefinitions;
976 std::vector<unsigned> CtxIndices;
977 std::vector<std::pair<Stmt*, Context> > SavedContexts;
981 // index 0 is a placeholder for undefined variables (aka phi-nodes).
982 VarDefinitions.push_back(VarDefinition(0, 0u, getEmptyContext()));
985 /// Look up a definition, within the given context.
986 const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
987 const unsigned *i = Ctx.lookup(D);
990 assert(*i < VarDefinitions.size());
991 return &VarDefinitions[*i];
994 /// Look up the definition for D within the given context. Returns
995 /// NULL if the expression is not statically known. If successful, also
996 /// modifies Ctx to hold the context of the return Expr.
997 const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
998 const unsigned *P = Ctx.lookup(D);
1004 if (VarDefinitions[i].Exp) {
1005 Ctx = VarDefinitions[i].Ctx;
1006 return VarDefinitions[i].Exp;
1008 i = VarDefinitions[i].Ref;
1013 Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
1015 /// Return the next context after processing S. This function is used by
1016 /// clients of the class to get the appropriate context when traversing the
1017 /// CFG. It must be called for every assignment or DeclStmt.
1018 Context getNextContext(unsigned &CtxIndex, Stmt *S, Context C) {
1019 if (SavedContexts[CtxIndex+1].first == S) {
1021 Context Result = SavedContexts[CtxIndex].second;
1027 void dumpVarDefinitionName(unsigned i) {
1029 llvm::errs() << "Undefined";
1032 const NamedDecl *Dec = VarDefinitions[i].Dec;
1034 llvm::errs() << "<<NULL>>";
1037 Dec->printName(llvm::errs());
1038 llvm::errs() << "." << i << " " << ((const void*) Dec);
1041 /// Dumps an ASCII representation of the variable map to llvm::errs()
1043 for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
1044 const Expr *Exp = VarDefinitions[i].Exp;
1045 unsigned Ref = VarDefinitions[i].Ref;
1047 dumpVarDefinitionName(i);
1048 llvm::errs() << " = ";
1049 if (Exp) Exp->dump();
1051 dumpVarDefinitionName(Ref);
1052 llvm::errs() << "\n";
1057 /// Dumps an ASCII representation of a Context to llvm::errs()
1058 void dumpContext(Context C) {
1059 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
1060 const NamedDecl *D = I.getKey();
1061 D->printName(llvm::errs());
1062 const unsigned *i = C.lookup(D);
1063 llvm::errs() << " -> ";
1064 dumpVarDefinitionName(*i);
1065 llvm::errs() << "\n";
1069 /// Builds the variable map.
1070 void traverseCFG(CFG *CFGraph, PostOrderCFGView *SortedGraph,
1071 std::vector<CFGBlockInfo> &BlockInfo);
1074 // Get the current context index
1075 unsigned getContextIndex() { return SavedContexts.size()-1; }
1077 // Save the current context for later replay
1078 void saveContext(Stmt *S, Context C) {
1079 SavedContexts.push_back(std::make_pair(S,C));
1082 // Adds a new definition to the given context, and returns a new context.
1083 // This method should be called when declaring a new variable.
1084 Context addDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
1085 assert(!Ctx.contains(D));
1086 unsigned newID = VarDefinitions.size();
1087 Context NewCtx = ContextFactory.add(Ctx, D, newID);
1088 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
1092 // Add a new reference to an existing definition.
1093 Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
1094 unsigned newID = VarDefinitions.size();
1095 Context NewCtx = ContextFactory.add(Ctx, D, newID);
1096 VarDefinitions.push_back(VarDefinition(D, i, Ctx));
1100 // Updates a definition only if that definition is already in the map.
1101 // This method should be called when assigning to an existing variable.
1102 Context updateDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
1103 if (Ctx.contains(D)) {
1104 unsigned newID = VarDefinitions.size();
1105 Context NewCtx = ContextFactory.remove(Ctx, D);
1106 NewCtx = ContextFactory.add(NewCtx, D, newID);
1107 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
1113 // Removes a definition from the context, but keeps the variable name
1114 // as a valid variable. The index 0 is a placeholder for cleared definitions.
1115 Context clearDefinition(const NamedDecl *D, Context Ctx) {
1116 Context NewCtx = Ctx;
1117 if (NewCtx.contains(D)) {
1118 NewCtx = ContextFactory.remove(NewCtx, D);
1119 NewCtx = ContextFactory.add(NewCtx, D, 0);
1124 // Remove a definition entirely frmo the context.
1125 Context removeDefinition(const NamedDecl *D, Context Ctx) {
1126 Context NewCtx = Ctx;
1127 if (NewCtx.contains(D)) {
1128 NewCtx = ContextFactory.remove(NewCtx, D);
1133 Context intersectContexts(Context C1, Context C2);
1134 Context createReferenceContext(Context C);
1135 void intersectBackEdge(Context C1, Context C2);
1137 friend class VarMapBuilder;
1141 // This has to be defined after LocalVariableMap.
1142 CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
1143 return CFGBlockInfo(M.getEmptyContext());
1147 /// Visitor which builds a LocalVariableMap
1148 class VarMapBuilder : public StmtVisitor<VarMapBuilder> {
1150 LocalVariableMap* VMap;
1151 LocalVariableMap::Context Ctx;
1153 VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
1154 : VMap(VM), Ctx(C) {}
1156 void VisitDeclStmt(DeclStmt *S);
1157 void VisitBinaryOperator(BinaryOperator *BO);
1161 // Add new local variables to the variable map
1162 void VarMapBuilder::VisitDeclStmt(DeclStmt *S) {
1163 bool modifiedCtx = false;
1164 DeclGroupRef DGrp = S->getDeclGroup();
1165 for (DeclGroupRef::iterator I = DGrp.begin(), E = DGrp.end(); I != E; ++I) {
1166 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(*I)) {
1167 Expr *E = VD->getInit();
1169 // Add local variables with trivial type to the variable map
1170 QualType T = VD->getType();
1171 if (T.isTrivialType(VD->getASTContext())) {
1172 Ctx = VMap->addDefinition(VD, E, Ctx);
1178 VMap->saveContext(S, Ctx);
1181 // Update local variable definitions in variable map
1182 void VarMapBuilder::VisitBinaryOperator(BinaryOperator *BO) {
1183 if (!BO->isAssignmentOp())
1186 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
1188 // Update the variable map and current context.
1189 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
1190 ValueDecl *VDec = DRE->getDecl();
1191 if (Ctx.lookup(VDec)) {
1192 if (BO->getOpcode() == BO_Assign)
1193 Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
1195 // FIXME -- handle compound assignment operators
1196 Ctx = VMap->clearDefinition(VDec, Ctx);
1197 VMap->saveContext(BO, Ctx);
1203 // Computes the intersection of two contexts. The intersection is the
1204 // set of variables which have the same definition in both contexts;
1205 // variables with different definitions are discarded.
1206 LocalVariableMap::Context
1207 LocalVariableMap::intersectContexts(Context C1, Context C2) {
1208 Context Result = C1;
1209 for (Context::iterator I = C1.begin(), E = C1.end(); I != E; ++I) {
1210 const NamedDecl *Dec = I.getKey();
1211 unsigned i1 = I.getData();
1212 const unsigned *i2 = C2.lookup(Dec);
1213 if (!i2) // variable doesn't exist on second path
1214 Result = removeDefinition(Dec, Result);
1215 else if (*i2 != i1) // variable exists, but has different definition
1216 Result = clearDefinition(Dec, Result);
1221 // For every variable in C, create a new variable that refers to the
1222 // definition in C. Return a new context that contains these new variables.
1223 // (We use this for a naive implementation of SSA on loop back-edges.)
1224 LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
1225 Context Result = getEmptyContext();
1226 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
1227 const NamedDecl *Dec = I.getKey();
1228 unsigned i = I.getData();
1229 Result = addReference(Dec, i, Result);
1234 // This routine also takes the intersection of C1 and C2, but it does so by
1235 // altering the VarDefinitions. C1 must be the result of an earlier call to
1236 // createReferenceContext.
1237 void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
1238 for (Context::iterator I = C1.begin(), E = C1.end(); I != E; ++I) {
1239 const NamedDecl *Dec = I.getKey();
1240 unsigned i1 = I.getData();
1241 VarDefinition *VDef = &VarDefinitions[i1];
1242 assert(VDef->isReference());
1244 const unsigned *i2 = C2.lookup(Dec);
1245 if (!i2 || (*i2 != i1))
1246 VDef->Ref = 0; // Mark this variable as undefined
1251 // Traverse the CFG in topological order, so all predecessors of a block
1252 // (excluding back-edges) are visited before the block itself. At
1253 // each point in the code, we calculate a Context, which holds the set of
1254 // variable definitions which are visible at that point in execution.
1255 // Visible variables are mapped to their definitions using an array that
1256 // contains all definitions.
1258 // At join points in the CFG, the set is computed as the intersection of
1259 // the incoming sets along each edge, E.g.
1261 // { Context | VarDefinitions }
1262 // int x = 0; { x -> x1 | x1 = 0 }
1263 // int y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
1264 // if (b) x = 1; { x -> x2, y -> y1 | x2 = 1, y1 = 0, ... }
1265 // else x = 2; { x -> x3, y -> y1 | x3 = 2, x2 = 1, ... }
1266 // ... { y -> y1 (x is unknown) | x3 = 2, x2 = 1, ... }
1268 // This is essentially a simpler and more naive version of the standard SSA
1269 // algorithm. Those definitions that remain in the intersection are from blocks
1270 // that strictly dominate the current block. We do not bother to insert proper
1271 // phi nodes, because they are not used in our analysis; instead, wherever
1272 // a phi node would be required, we simply remove that definition from the
1273 // context (E.g. x above).
1275 // The initial traversal does not capture back-edges, so those need to be
1276 // handled on a separate pass. Whenever the first pass encounters an
1277 // incoming back edge, it duplicates the context, creating new definitions
1278 // that refer back to the originals. (These correspond to places where SSA
1279 // might have to insert a phi node.) On the second pass, these definitions are
1280 // set to NULL if the variable has changed on the back-edge (i.e. a phi
1281 // node was actually required.) E.g.
1283 // { Context | VarDefinitions }
1284 // int x = 0, y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
1285 // while (b) { x -> x2, y -> y1 | [1st:] x2=x1; [2nd:] x2=NULL; }
1286 // x = x+1; { x -> x3, y -> y1 | x3 = x2 + 1, ... }
1287 // ... { y -> y1 | x3 = 2, x2 = 1, ... }
1289 void LocalVariableMap::traverseCFG(CFG *CFGraph,
1290 PostOrderCFGView *SortedGraph,
1291 std::vector<CFGBlockInfo> &BlockInfo) {
1292 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
1294 CtxIndices.resize(CFGraph->getNumBlockIDs());
1296 for (PostOrderCFGView::iterator I = SortedGraph->begin(),
1297 E = SortedGraph->end(); I!= E; ++I) {
1298 const CFGBlock *CurrBlock = *I;
1299 int CurrBlockID = CurrBlock->getBlockID();
1300 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
1302 VisitedBlocks.insert(CurrBlock);
1304 // Calculate the entry context for the current block
1305 bool HasBackEdges = false;
1306 bool CtxInit = true;
1307 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
1308 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
1309 // if *PI -> CurrBlock is a back edge, so skip it
1310 if (*PI == 0 || !VisitedBlocks.alreadySet(*PI)) {
1311 HasBackEdges = true;
1315 int PrevBlockID = (*PI)->getBlockID();
1316 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
1319 CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
1323 CurrBlockInfo->EntryContext =
1324 intersectContexts(CurrBlockInfo->EntryContext,
1325 PrevBlockInfo->ExitContext);
1329 // Duplicate the context if we have back-edges, so we can call
1330 // intersectBackEdges later.
1332 CurrBlockInfo->EntryContext =
1333 createReferenceContext(CurrBlockInfo->EntryContext);
1335 // Create a starting context index for the current block
1336 saveContext(0, CurrBlockInfo->EntryContext);
1337 CurrBlockInfo->EntryIndex = getContextIndex();
1339 // Visit all the statements in the basic block.
1340 VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
1341 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
1342 BE = CurrBlock->end(); BI != BE; ++BI) {
1343 switch (BI->getKind()) {
1344 case CFGElement::Statement: {
1345 const CFGStmt *CS = cast<CFGStmt>(&*BI);
1346 VMapBuilder.Visit(const_cast<Stmt*>(CS->getStmt()));
1353 CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
1355 // Mark variables on back edges as "unknown" if they've been changed.
1356 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
1357 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
1358 // if CurrBlock -> *SI is *not* a back edge
1359 if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
1362 CFGBlock *FirstLoopBlock = *SI;
1363 Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
1364 Context LoopEnd = CurrBlockInfo->ExitContext;
1365 intersectBackEdge(LoopBegin, LoopEnd);
1369 // Put an extra entry at the end of the indexed context array
1370 unsigned exitID = CFGraph->getExit().getBlockID();
1371 saveContext(0, BlockInfo[exitID].ExitContext);
1374 /// Find the appropriate source locations to use when producing diagnostics for
1375 /// each block in the CFG.
1376 static void findBlockLocations(CFG *CFGraph,
1377 PostOrderCFGView *SortedGraph,
1378 std::vector<CFGBlockInfo> &BlockInfo) {
1379 for (PostOrderCFGView::iterator I = SortedGraph->begin(),
1380 E = SortedGraph->end(); I!= E; ++I) {
1381 const CFGBlock *CurrBlock = *I;
1382 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
1384 // Find the source location of the last statement in the block, if the
1385 // block is not empty.
1386 if (const Stmt *S = CurrBlock->getTerminator()) {
1387 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getLocStart();
1389 for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
1390 BE = CurrBlock->rend(); BI != BE; ++BI) {
1391 // FIXME: Handle other CFGElement kinds.
1392 if (const CFGStmt *CS = dyn_cast<CFGStmt>(&*BI)) {
1393 CurrBlockInfo->ExitLoc = CS->getStmt()->getLocStart();
1399 if (!CurrBlockInfo->ExitLoc.isInvalid()) {
1400 // This block contains at least one statement. Find the source location
1401 // of the first statement in the block.
1402 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
1403 BE = CurrBlock->end(); BI != BE; ++BI) {
1404 // FIXME: Handle other CFGElement kinds.
1405 if (const CFGStmt *CS = dyn_cast<CFGStmt>(&*BI)) {
1406 CurrBlockInfo->EntryLoc = CS->getStmt()->getLocStart();
1410 } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
1411 CurrBlock != &CFGraph->getExit()) {
1412 // The block is empty, and has a single predecessor. Use its exit
1414 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
1415 BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
1420 /// \brief Class which implements the core thread safety analysis routines.
1421 class ThreadSafetyAnalyzer {
1422 friend class BuildLockset;
1424 ThreadSafetyHandler &Handler;
1425 LocalVariableMap LocalVarMap;
1426 FactManager FactMan;
1427 std::vector<CFGBlockInfo> BlockInfo;
1430 ThreadSafetyAnalyzer(ThreadSafetyHandler &H) : Handler(H) {}
1432 void addLock(FactSet &FSet, const SExpr &Mutex, const LockData &LDat);
1433 void removeLock(FactSet &FSet, const SExpr &Mutex,
1434 SourceLocation UnlockLoc, bool FullyRemove=false);
1436 template <typename AttrType>
1437 void getMutexIDs(MutexIDList &Mtxs, AttrType *Attr, Expr *Exp,
1438 const NamedDecl *D, VarDecl *SelfDecl=0);
1440 template <class AttrType>
1441 void getMutexIDs(MutexIDList &Mtxs, AttrType *Attr, Expr *Exp,
1443 const CFGBlock *PredBlock, const CFGBlock *CurrBlock,
1444 Expr *BrE, bool Neg);
1446 const CallExpr* getTrylockCallExpr(const Stmt *Cond, LocalVarContext C,
1449 void getEdgeLockset(FactSet &Result, const FactSet &ExitSet,
1450 const CFGBlock* PredBlock,
1451 const CFGBlock *CurrBlock);
1453 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
1454 SourceLocation JoinLoc,
1455 LockErrorKind LEK1, LockErrorKind LEK2,
1458 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
1459 SourceLocation JoinLoc, LockErrorKind LEK1,
1461 intersectAndWarn(FSet1, FSet2, JoinLoc, LEK1, LEK1, Modify);
1464 void runAnalysis(AnalysisDeclContext &AC);
1468 /// \brief Add a new lock to the lockset, warning if the lock is already there.
1469 /// \param Mutex -- the Mutex expression for the lock
1470 /// \param LDat -- the LockData for the lock
1471 void ThreadSafetyAnalyzer::addLock(FactSet &FSet, const SExpr &Mutex,
1472 const LockData &LDat) {
1473 // FIXME: deal with acquired before/after annotations.
1474 // FIXME: Don't always warn when we have support for reentrant locks.
1475 if (Mutex.shouldIgnore())
1478 if (FSet.findLock(FactMan, Mutex)) {
1479 Handler.handleDoubleLock(Mutex.toString(), LDat.AcquireLoc);
1481 FSet.addLock(FactMan, Mutex, LDat);
1486 /// \brief Remove a lock from the lockset, warning if the lock is not there.
1487 /// \param Mutex The lock expression corresponding to the lock to be removed
1488 /// \param UnlockLoc The source location of the unlock (only used in error msg)
1489 void ThreadSafetyAnalyzer::removeLock(FactSet &FSet,
1491 SourceLocation UnlockLoc,
1493 if (Mutex.shouldIgnore())
1496 const LockData *LDat = FSet.findLock(FactMan, Mutex);
1498 Handler.handleUnmatchedUnlock(Mutex.toString(), UnlockLoc);
1502 if (LDat->UnderlyingMutex.isValid()) {
1503 // This is scoped lockable object, which manages the real mutex.
1505 // We're destroying the managing object.
1506 // Remove the underlying mutex if it exists; but don't warn.
1507 if (FSet.findLock(FactMan, LDat->UnderlyingMutex))
1508 FSet.removeLock(FactMan, LDat->UnderlyingMutex);
1510 // We're releasing the underlying mutex, but not destroying the
1511 // managing object. Warn on dual release.
1512 if (!FSet.findLock(FactMan, LDat->UnderlyingMutex)) {
1513 Handler.handleUnmatchedUnlock(LDat->UnderlyingMutex.toString(),
1516 FSet.removeLock(FactMan, LDat->UnderlyingMutex);
1520 FSet.removeLock(FactMan, Mutex);
1524 /// \brief Extract the list of mutexIDs from the attribute on an expression,
1525 /// and push them onto Mtxs, discarding any duplicates.
1526 template <typename AttrType>
1527 void ThreadSafetyAnalyzer::getMutexIDs(MutexIDList &Mtxs, AttrType *Attr,
1528 Expr *Exp, const NamedDecl *D,
1529 VarDecl *SelfDecl) {
1530 typedef typename AttrType::args_iterator iterator_type;
1532 if (Attr->args_size() == 0) {
1533 // The mutex held is the "this" object.
1534 SExpr Mu(0, Exp, D, SelfDecl);
1536 SExpr::warnInvalidLock(Handler, 0, Exp, D);
1538 Mtxs.push_back_nodup(Mu);
1542 for (iterator_type I=Attr->args_begin(), E=Attr->args_end(); I != E; ++I) {
1543 SExpr Mu(*I, Exp, D, SelfDecl);
1545 SExpr::warnInvalidLock(Handler, *I, Exp, D);
1547 Mtxs.push_back_nodup(Mu);
1552 /// \brief Extract the list of mutexIDs from a trylock attribute. If the
1553 /// trylock applies to the given edge, then push them onto Mtxs, discarding
1555 template <class AttrType>
1556 void ThreadSafetyAnalyzer::getMutexIDs(MutexIDList &Mtxs, AttrType *Attr,
1557 Expr *Exp, const NamedDecl *D,
1558 const CFGBlock *PredBlock,
1559 const CFGBlock *CurrBlock,
1560 Expr *BrE, bool Neg) {
1561 // Find out which branch has the lock
1563 if (CXXBoolLiteralExpr *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE)) {
1564 branch = BLE->getValue();
1566 else if (IntegerLiteral *ILE = dyn_cast_or_null<IntegerLiteral>(BrE)) {
1567 branch = ILE->getValue().getBoolValue();
1569 int branchnum = branch ? 0 : 1;
1570 if (Neg) branchnum = !branchnum;
1572 // If we've taken the trylock branch, then add the lock
1574 for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1575 SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1576 if (*SI == CurrBlock && i == branchnum) {
1577 getMutexIDs(Mtxs, Attr, Exp, D);
1583 bool getStaticBooleanValue(Expr* E, bool& TCond) {
1584 if (isa<CXXNullPtrLiteralExpr>(E) || isa<GNUNullExpr>(E)) {
1587 } else if (CXXBoolLiteralExpr *BLE = dyn_cast<CXXBoolLiteralExpr>(E)) {
1588 TCond = BLE->getValue();
1590 } else if (IntegerLiteral *ILE = dyn_cast<IntegerLiteral>(E)) {
1591 TCond = ILE->getValue().getBoolValue();
1593 } else if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
1594 return getStaticBooleanValue(CE->getSubExpr(), TCond);
1600 // If Cond can be traced back to a function call, return the call expression.
1601 // The negate variable should be called with false, and will be set to true
1602 // if the function call is negated, e.g. if (!mu.tryLock(...))
1603 const CallExpr* ThreadSafetyAnalyzer::getTrylockCallExpr(const Stmt *Cond,
1609 if (const CallExpr *CallExp = dyn_cast<CallExpr>(Cond)) {
1612 else if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) {
1613 return getTrylockCallExpr(PE->getSubExpr(), C, Negate);
1615 else if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Cond)) {
1616 return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1618 else if (const ExprWithCleanups* EWC = dyn_cast<ExprWithCleanups>(Cond)) {
1619 return getTrylockCallExpr(EWC->getSubExpr(), C, Negate);
1621 else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1622 const Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1623 return getTrylockCallExpr(E, C, Negate);
1625 else if (const UnaryOperator *UOP = dyn_cast<UnaryOperator>(Cond)) {
1626 if (UOP->getOpcode() == UO_LNot) {
1628 return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1632 else if (const BinaryOperator *BOP = dyn_cast<BinaryOperator>(Cond)) {
1633 if (BOP->getOpcode() == BO_EQ || BOP->getOpcode() == BO_NE) {
1634 if (BOP->getOpcode() == BO_NE)
1638 if (getStaticBooleanValue(BOP->getRHS(), TCond)) {
1639 if (!TCond) Negate = !Negate;
1640 return getTrylockCallExpr(BOP->getLHS(), C, Negate);
1642 else if (getStaticBooleanValue(BOP->getLHS(), TCond)) {
1643 if (!TCond) Negate = !Negate;
1644 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1650 // FIXME -- handle && and || as well.
1655 /// \brief Find the lockset that holds on the edge between PredBlock
1656 /// and CurrBlock. The edge set is the exit set of PredBlock (passed
1657 /// as the ExitSet parameter) plus any trylocks, which are conditionally held.
1658 void ThreadSafetyAnalyzer::getEdgeLockset(FactSet& Result,
1659 const FactSet &ExitSet,
1660 const CFGBlock *PredBlock,
1661 const CFGBlock *CurrBlock) {
1664 if (!PredBlock->getTerminatorCondition())
1667 bool Negate = false;
1668 const Stmt *Cond = PredBlock->getTerminatorCondition();
1669 const CFGBlockInfo *PredBlockInfo = &BlockInfo[PredBlock->getBlockID()];
1670 const LocalVarContext &LVarCtx = PredBlockInfo->ExitContext;
1673 const_cast<CallExpr*>(getTrylockCallExpr(Cond, LVarCtx, Negate));
1677 NamedDecl *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1678 if(!FunDecl || !FunDecl->hasAttrs())
1682 MutexIDList ExclusiveLocksToAdd;
1683 MutexIDList SharedLocksToAdd;
1685 // If the condition is a call to a Trylock function, then grab the attributes
1686 AttrVec &ArgAttrs = FunDecl->getAttrs();
1687 for (unsigned i = 0; i < ArgAttrs.size(); ++i) {
1688 Attr *Attr = ArgAttrs[i];
1689 switch (Attr->getKind()) {
1690 case attr::ExclusiveTrylockFunction: {
1691 ExclusiveTrylockFunctionAttr *A =
1692 cast<ExclusiveTrylockFunctionAttr>(Attr);
1693 getMutexIDs(ExclusiveLocksToAdd, A, Exp, FunDecl,
1694 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1697 case attr::SharedTrylockFunction: {
1698 SharedTrylockFunctionAttr *A =
1699 cast<SharedTrylockFunctionAttr>(Attr);
1700 getMutexIDs(SharedLocksToAdd, A, Exp, FunDecl,
1701 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1709 // Add and remove locks.
1710 SourceLocation Loc = Exp->getExprLoc();
1711 for (unsigned i=0,n=ExclusiveLocksToAdd.size(); i<n; ++i) {
1712 addLock(Result, ExclusiveLocksToAdd[i],
1713 LockData(Loc, LK_Exclusive));
1715 for (unsigned i=0,n=SharedLocksToAdd.size(); i<n; ++i) {
1716 addLock(Result, SharedLocksToAdd[i],
1717 LockData(Loc, LK_Shared));
1722 /// \brief We use this class to visit different types of expressions in
1723 /// CFGBlocks, and build up the lockset.
1724 /// An expression may cause us to add or remove locks from the lockset, or else
1725 /// output error messages related to missing locks.
1726 /// FIXME: In future, we may be able to not inherit from a visitor.
1727 class BuildLockset : public StmtVisitor<BuildLockset> {
1728 friend class ThreadSafetyAnalyzer;
1730 ThreadSafetyAnalyzer *Analyzer;
1732 LocalVariableMap::Context LVarCtx;
1736 const ValueDecl *getValueDecl(Expr *Exp);
1738 void warnIfMutexNotHeld(const NamedDecl *D, Expr *Exp, AccessKind AK,
1739 Expr *MutexExp, ProtectedOperationKind POK);
1740 void warnIfMutexHeld(const NamedDecl *D, Expr *Exp, Expr *MutexExp);
1742 void checkAccess(Expr *Exp, AccessKind AK);
1743 void checkDereference(Expr *Exp, AccessKind AK);
1744 void handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD = 0);
1747 BuildLockset(ThreadSafetyAnalyzer *Anlzr, CFGBlockInfo &Info)
1748 : StmtVisitor<BuildLockset>(),
1750 FSet(Info.EntrySet),
1751 LVarCtx(Info.EntryContext),
1752 CtxIndex(Info.EntryIndex)
1755 void VisitUnaryOperator(UnaryOperator *UO);
1756 void VisitBinaryOperator(BinaryOperator *BO);
1757 void VisitCastExpr(CastExpr *CE);
1758 void VisitCallExpr(CallExpr *Exp);
1759 void VisitCXXConstructExpr(CXXConstructExpr *Exp);
1760 void VisitDeclStmt(DeclStmt *S);
1764 /// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs
1765 const ValueDecl *BuildLockset::getValueDecl(Expr *Exp) {
1766 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Exp))
1767 return DR->getDecl();
1769 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp))
1770 return ME->getMemberDecl();
1775 /// \brief Warn if the LSet does not contain a lock sufficient to protect access
1776 /// of at least the passed in AccessKind.
1777 void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, Expr *Exp,
1778 AccessKind AK, Expr *MutexExp,
1779 ProtectedOperationKind POK) {
1780 LockKind LK = getLockKindFromAccessKind(AK);
1782 SExpr Mutex(MutexExp, Exp, D);
1783 if (!Mutex.isValid()) {
1784 SExpr::warnInvalidLock(Analyzer->Handler, MutexExp, Exp, D);
1786 } else if (Mutex.shouldIgnore()) {
1790 LockData* LDat = FSet.findLockUniv(Analyzer->FactMan, Mutex);
1791 bool NoError = true;
1793 // No exact match found. Look for a partial match.
1794 FactEntry* FEntry = FSet.findPartialMatch(Analyzer->FactMan, Mutex);
1796 // Warn that there's no precise match.
1797 LDat = &FEntry->LDat;
1798 std::string PartMatchStr = FEntry->MutID.toString();
1799 StringRef PartMatchName(PartMatchStr);
1800 Analyzer->Handler.handleMutexNotHeld(D, POK, Mutex.toString(), LK,
1801 Exp->getExprLoc(), &PartMatchName);
1803 // Warn that there's no match at all.
1804 Analyzer->Handler.handleMutexNotHeld(D, POK, Mutex.toString(), LK,
1809 // Make sure the mutex we found is the right kind.
1810 if (NoError && LDat && !LDat->isAtLeast(LK))
1811 Analyzer->Handler.handleMutexNotHeld(D, POK, Mutex.toString(), LK,
1815 /// \brief Warn if the LSet contains the given lock.
1816 void BuildLockset::warnIfMutexHeld(const NamedDecl *D, Expr* Exp,
1818 SExpr Mutex(MutexExp, Exp, D);
1819 if (!Mutex.isValid()) {
1820 SExpr::warnInvalidLock(Analyzer->Handler, MutexExp, Exp, D);
1824 LockData* LDat = FSet.findLock(Analyzer->FactMan, Mutex);
1826 std::string DeclName = D->getNameAsString();
1827 StringRef DeclNameSR (DeclName);
1828 Analyzer->Handler.handleFunExcludesLock(DeclNameSR, Mutex.toString(),
1834 /// \brief This method identifies variable dereferences and checks pt_guarded_by
1835 /// and pt_guarded_var annotations. Note that we only check these annotations
1836 /// at the time a pointer is dereferenced.
1837 /// FIXME: We need to check for other types of pointer dereferences
1838 /// (e.g. [], ->) and deal with them here.
1839 /// \param Exp An expression that has been read or written.
1840 void BuildLockset::checkDereference(Expr *Exp, AccessKind AK) {
1841 UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp);
1842 if (!UO || UO->getOpcode() != clang::UO_Deref)
1844 Exp = UO->getSubExpr()->IgnoreParenCasts();
1846 const ValueDecl *D = getValueDecl(Exp);
1847 if(!D || !D->hasAttrs())
1850 if (D->getAttr<PtGuardedVarAttr>() && FSet.isEmpty())
1851 Analyzer->Handler.handleNoMutexHeld(D, POK_VarDereference, AK,
1854 const AttrVec &ArgAttrs = D->getAttrs();
1855 for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
1856 if (PtGuardedByAttr *PGBAttr = dyn_cast<PtGuardedByAttr>(ArgAttrs[i]))
1857 warnIfMutexNotHeld(D, Exp, AK, PGBAttr->getArg(), POK_VarDereference);
1860 /// \brief Checks guarded_by and guarded_var attributes.
1861 /// Whenever we identify an access (read or write) of a DeclRefExpr or
1862 /// MemberExpr, we need to check whether there are any guarded_by or
1863 /// guarded_var attributes, and make sure we hold the appropriate mutexes.
1864 void BuildLockset::checkAccess(Expr *Exp, AccessKind AK) {
1865 const ValueDecl *D = getValueDecl(Exp);
1866 if(!D || !D->hasAttrs())
1869 if (D->getAttr<GuardedVarAttr>() && FSet.isEmpty())
1870 Analyzer->Handler.handleNoMutexHeld(D, POK_VarAccess, AK,
1873 const AttrVec &ArgAttrs = D->getAttrs();
1874 for(unsigned i = 0, Size = ArgAttrs.size(); i < Size; ++i)
1875 if (GuardedByAttr *GBAttr = dyn_cast<GuardedByAttr>(ArgAttrs[i]))
1876 warnIfMutexNotHeld(D, Exp, AK, GBAttr->getArg(), POK_VarAccess);
1879 /// \brief Process a function call, method call, constructor call,
1880 /// or destructor call. This involves looking at the attributes on the
1881 /// corresponding function/method/constructor/destructor, issuing warnings,
1882 /// and updating the locksets accordingly.
1884 /// FIXME: For classes annotated with one of the guarded annotations, we need
1885 /// to treat const method calls as reads and non-const method calls as writes,
1886 /// and check that the appropriate locks are held. Non-const method calls with
1887 /// the same signature as const method calls can be also treated as reads.
1889 void BuildLockset::handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD) {
1890 const AttrVec &ArgAttrs = D->getAttrs();
1891 MutexIDList ExclusiveLocksToAdd;
1892 MutexIDList SharedLocksToAdd;
1893 MutexIDList LocksToRemove;
1895 for(unsigned i = 0; i < ArgAttrs.size(); ++i) {
1896 Attr *At = const_cast<Attr*>(ArgAttrs[i]);
1897 switch (At->getKind()) {
1898 // When we encounter an exclusive lock function, we need to add the lock
1899 // to our lockset with kind exclusive.
1900 case attr::ExclusiveLockFunction: {
1901 ExclusiveLockFunctionAttr *A = cast<ExclusiveLockFunctionAttr>(At);
1902 Analyzer->getMutexIDs(ExclusiveLocksToAdd, A, Exp, D, VD);
1906 // When we encounter a shared lock function, we need to add the lock
1907 // to our lockset with kind shared.
1908 case attr::SharedLockFunction: {
1909 SharedLockFunctionAttr *A = cast<SharedLockFunctionAttr>(At);
1910 Analyzer->getMutexIDs(SharedLocksToAdd, A, Exp, D, VD);
1914 // When we encounter an unlock function, we need to remove unlocked
1915 // mutexes from the lockset, and flag a warning if they are not there.
1916 case attr::UnlockFunction: {
1917 UnlockFunctionAttr *A = cast<UnlockFunctionAttr>(At);
1918 Analyzer->getMutexIDs(LocksToRemove, A, Exp, D, VD);
1922 case attr::ExclusiveLocksRequired: {
1923 ExclusiveLocksRequiredAttr *A = cast<ExclusiveLocksRequiredAttr>(At);
1925 for (ExclusiveLocksRequiredAttr::args_iterator
1926 I = A->args_begin(), E = A->args_end(); I != E; ++I)
1927 warnIfMutexNotHeld(D, Exp, AK_Written, *I, POK_FunctionCall);
1931 case attr::SharedLocksRequired: {
1932 SharedLocksRequiredAttr *A = cast<SharedLocksRequiredAttr>(At);
1934 for (SharedLocksRequiredAttr::args_iterator I = A->args_begin(),
1935 E = A->args_end(); I != E; ++I)
1936 warnIfMutexNotHeld(D, Exp, AK_Read, *I, POK_FunctionCall);
1940 case attr::LocksExcluded: {
1941 LocksExcludedAttr *A = cast<LocksExcludedAttr>(At);
1943 for (LocksExcludedAttr::args_iterator I = A->args_begin(),
1944 E = A->args_end(); I != E; ++I) {
1945 warnIfMutexHeld(D, Exp, *I);
1950 // Ignore other (non thread-safety) attributes
1956 // Figure out if we're calling the constructor of scoped lockable class
1957 bool isScopedVar = false;
1959 if (const CXXConstructorDecl *CD = dyn_cast<const CXXConstructorDecl>(D)) {
1960 const CXXRecordDecl* PD = CD->getParent();
1961 if (PD && PD->getAttr<ScopedLockableAttr>())
1967 SourceLocation Loc = Exp->getExprLoc();
1968 for (unsigned i=0,n=ExclusiveLocksToAdd.size(); i<n; ++i) {
1969 Analyzer->addLock(FSet, ExclusiveLocksToAdd[i],
1970 LockData(Loc, LK_Exclusive, isScopedVar));
1972 for (unsigned i=0,n=SharedLocksToAdd.size(); i<n; ++i) {
1973 Analyzer->addLock(FSet, SharedLocksToAdd[i],
1974 LockData(Loc, LK_Shared, isScopedVar));
1977 // Add the managing object as a dummy mutex, mapped to the underlying mutex.
1978 // FIXME -- this doesn't work if we acquire multiple locks.
1980 SourceLocation MLoc = VD->getLocation();
1981 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue, VD->getLocation());
1982 SExpr SMutex(&DRE, 0, 0);
1984 for (unsigned i=0,n=ExclusiveLocksToAdd.size(); i<n; ++i) {
1985 Analyzer->addLock(FSet, SMutex, LockData(MLoc, LK_Exclusive,
1986 ExclusiveLocksToAdd[i]));
1988 for (unsigned i=0,n=SharedLocksToAdd.size(); i<n; ++i) {
1989 Analyzer->addLock(FSet, SMutex, LockData(MLoc, LK_Shared,
1990 SharedLocksToAdd[i]));
1995 // FIXME -- should only fully remove if the attribute refers to 'this'.
1996 bool Dtor = isa<CXXDestructorDecl>(D);
1997 for (unsigned i=0,n=LocksToRemove.size(); i<n; ++i) {
1998 Analyzer->removeLock(FSet, LocksToRemove[i], Loc, Dtor);
2003 /// \brief For unary operations which read and write a variable, we need to
2004 /// check whether we hold any required mutexes. Reads are checked in
2006 void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
2007 switch (UO->getOpcode()) {
2008 case clang::UO_PostDec:
2009 case clang::UO_PostInc:
2010 case clang::UO_PreDec:
2011 case clang::UO_PreInc: {
2012 Expr *SubExp = UO->getSubExpr()->IgnoreParenCasts();
2013 checkAccess(SubExp, AK_Written);
2014 checkDereference(SubExp, AK_Written);
2022 /// For binary operations which assign to a variable (writes), we need to check
2023 /// whether we hold any required mutexes.
2024 /// FIXME: Deal with non-primitive types.
2025 void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
2026 if (!BO->isAssignmentOp())
2029 // adjust the context
2030 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
2032 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
2033 checkAccess(LHSExp, AK_Written);
2034 checkDereference(LHSExp, AK_Written);
2037 /// Whenever we do an LValue to Rvalue cast, we are reading a variable and
2038 /// need to ensure we hold any required mutexes.
2039 /// FIXME: Deal with non-primitive types.
2040 void BuildLockset::VisitCastExpr(CastExpr *CE) {
2041 if (CE->getCastKind() != CK_LValueToRValue)
2043 Expr *SubExp = CE->getSubExpr()->IgnoreParenCasts();
2044 checkAccess(SubExp, AK_Read);
2045 checkDereference(SubExp, AK_Read);
2049 void BuildLockset::VisitCallExpr(CallExpr *Exp) {
2050 NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
2051 if(!D || !D->hasAttrs())
2056 void BuildLockset::VisitCXXConstructExpr(CXXConstructExpr *Exp) {
2057 // FIXME -- only handles constructors in DeclStmt below.
2060 void BuildLockset::VisitDeclStmt(DeclStmt *S) {
2061 // adjust the context
2062 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
2064 DeclGroupRef DGrp = S->getDeclGroup();
2065 for (DeclGroupRef::iterator I = DGrp.begin(), E = DGrp.end(); I != E; ++I) {
2067 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(D)) {
2068 Expr *E = VD->getInit();
2069 // handle constructors that involve temporaries
2070 if (ExprWithCleanups *EWC = dyn_cast_or_null<ExprWithCleanups>(E))
2071 E = EWC->getSubExpr();
2073 if (CXXConstructExpr *CE = dyn_cast_or_null<CXXConstructExpr>(E)) {
2074 NamedDecl *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
2075 if (!CtorD || !CtorD->hasAttrs())
2077 handleCall(CE, CtorD, VD);
2085 /// \brief Compute the intersection of two locksets and issue warnings for any
2086 /// locks in the symmetric difference.
2088 /// This function is used at a merge point in the CFG when comparing the lockset
2089 /// of each branch being merged. For example, given the following sequence:
2090 /// A; if () then B; else C; D; we need to check that the lockset after B and C
2091 /// are the same. In the event of a difference, we use the intersection of these
2092 /// two locksets at the start of D.
2094 /// \param FSet1 The first lockset.
2095 /// \param FSet2 The second lockset.
2096 /// \param JoinLoc The location of the join point for error reporting
2097 /// \param LEK1 The error message to report if a mutex is missing from LSet1
2098 /// \param LEK2 The error message to report if a mutex is missing from Lset2
2099 void ThreadSafetyAnalyzer::intersectAndWarn(FactSet &FSet1,
2100 const FactSet &FSet2,
2101 SourceLocation JoinLoc,
2105 FactSet FSet1Orig = FSet1;
2107 for (FactSet::const_iterator I = FSet2.begin(), E = FSet2.end();
2109 const SExpr &FSet2Mutex = FactMan[*I].MutID;
2110 const LockData &LDat2 = FactMan[*I].LDat;
2112 if (const LockData *LDat1 = FSet1.findLock(FactMan, FSet2Mutex)) {
2113 if (LDat1->LKind != LDat2.LKind) {
2114 Handler.handleExclusiveAndShared(FSet2Mutex.toString(),
2117 if (Modify && LDat1->LKind != LK_Exclusive) {
2118 FSet1.removeLock(FactMan, FSet2Mutex);
2119 FSet1.addLock(FactMan, FSet2Mutex, LDat2);
2123 if (LDat2.UnderlyingMutex.isValid()) {
2124 if (FSet2.findLock(FactMan, LDat2.UnderlyingMutex)) {
2125 // If this is a scoped lock that manages another mutex, and if the
2126 // underlying mutex is still held, then warn about the underlying
2128 Handler.handleMutexHeldEndOfScope(LDat2.UnderlyingMutex.toString(),
2133 else if (!LDat2.Managed && !FSet2Mutex.isUniversal())
2134 Handler.handleMutexHeldEndOfScope(FSet2Mutex.toString(),
2140 for (FactSet::const_iterator I = FSet1.begin(), E = FSet1.end();
2142 const SExpr &FSet1Mutex = FactMan[*I].MutID;
2143 const LockData &LDat1 = FactMan[*I].LDat;
2145 if (!FSet2.findLock(FactMan, FSet1Mutex)) {
2146 if (LDat1.UnderlyingMutex.isValid()) {
2147 if (FSet1Orig.findLock(FactMan, LDat1.UnderlyingMutex)) {
2148 // If this is a scoped lock that manages another mutex, and if the
2149 // underlying mutex is still held, then warn about the underlying
2151 Handler.handleMutexHeldEndOfScope(LDat1.UnderlyingMutex.toString(),
2156 else if (!LDat1.Managed && !FSet1Mutex.isUniversal())
2157 Handler.handleMutexHeldEndOfScope(FSet1Mutex.toString(),
2161 FSet1.removeLock(FactMan, FSet1Mutex);
2168 /// \brief Check a function's CFG for thread-safety violations.
2170 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2171 /// at the end of each block, and issue warnings for thread safety violations.
2172 /// Each block in the CFG is traversed exactly once.
2173 void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
2174 CFG *CFGraph = AC.getCFG();
2175 if (!CFGraph) return;
2176 const NamedDecl *D = dyn_cast_or_null<NamedDecl>(AC.getDecl());
2178 // AC.dumpCFG(true);
2181 return; // Ignore anonymous functions for now.
2182 if (D->getAttr<NoThreadSafetyAnalysisAttr>())
2184 // FIXME: Do something a bit more intelligent inside constructor and
2185 // destructor code. Constructors and destructors must assume unique access
2186 // to 'this', so checks on member variable access is disabled, but we should
2187 // still enable checks on other objects.
2188 if (isa<CXXConstructorDecl>(D))
2189 return; // Don't check inside constructors.
2190 if (isa<CXXDestructorDecl>(D))
2191 return; // Don't check inside destructors.
2193 BlockInfo.resize(CFGraph->getNumBlockIDs(),
2194 CFGBlockInfo::getEmptyBlockInfo(LocalVarMap));
2196 // We need to explore the CFG via a "topological" ordering.
2197 // That way, we will be guaranteed to have information about required
2198 // predecessor locksets when exploring a new block.
2199 PostOrderCFGView *SortedGraph = AC.getAnalysis<PostOrderCFGView>();
2200 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
2202 // Mark entry block as reachable
2203 BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
2205 // Compute SSA names for local variables
2206 LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
2208 // Fill in source locations for all CFGBlocks.
2209 findBlockLocations(CFGraph, SortedGraph, BlockInfo);
2211 // Add locks from exclusive_locks_required and shared_locks_required
2212 // to initial lockset. Also turn off checking for lock and unlock functions.
2213 // FIXME: is there a more intelligent way to check lock/unlock functions?
2214 if (!SortedGraph->empty() && D->hasAttrs()) {
2215 const CFGBlock *FirstBlock = *SortedGraph->begin();
2216 FactSet &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
2217 const AttrVec &ArgAttrs = D->getAttrs();
2219 MutexIDList ExclusiveLocksToAdd;
2220 MutexIDList SharedLocksToAdd;
2222 SourceLocation Loc = D->getLocation();
2223 for (unsigned i = 0; i < ArgAttrs.size(); ++i) {
2224 Attr *Attr = ArgAttrs[i];
2225 Loc = Attr->getLocation();
2226 if (ExclusiveLocksRequiredAttr *A
2227 = dyn_cast<ExclusiveLocksRequiredAttr>(Attr)) {
2228 getMutexIDs(ExclusiveLocksToAdd, A, (Expr*) 0, D);
2229 } else if (SharedLocksRequiredAttr *A
2230 = dyn_cast<SharedLocksRequiredAttr>(Attr)) {
2231 getMutexIDs(SharedLocksToAdd, A, (Expr*) 0, D);
2232 } else if (isa<UnlockFunctionAttr>(Attr)) {
2233 // Don't try to check unlock functions for now
2235 } else if (isa<ExclusiveLockFunctionAttr>(Attr)) {
2236 // Don't try to check lock functions for now
2238 } else if (isa<SharedLockFunctionAttr>(Attr)) {
2239 // Don't try to check lock functions for now
2241 } else if (isa<ExclusiveTrylockFunctionAttr>(Attr)) {
2242 // Don't try to check trylock functions for now
2244 } else if (isa<SharedTrylockFunctionAttr>(Attr)) {
2245 // Don't try to check trylock functions for now
2250 // FIXME -- Loc can be wrong here.
2251 for (unsigned i=0,n=ExclusiveLocksToAdd.size(); i<n; ++i) {
2252 addLock(InitialLockset, ExclusiveLocksToAdd[i],
2253 LockData(Loc, LK_Exclusive));
2255 for (unsigned i=0,n=SharedLocksToAdd.size(); i<n; ++i) {
2256 addLock(InitialLockset, SharedLocksToAdd[i],
2257 LockData(Loc, LK_Shared));
2261 for (PostOrderCFGView::iterator I = SortedGraph->begin(),
2262 E = SortedGraph->end(); I!= E; ++I) {
2263 const CFGBlock *CurrBlock = *I;
2264 int CurrBlockID = CurrBlock->getBlockID();
2265 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
2267 // Use the default initial lockset in case there are no predecessors.
2268 VisitedBlocks.insert(CurrBlock);
2270 // Iterate through the predecessor blocks and warn if the lockset for all
2271 // predecessors is not the same. We take the entry lockset of the current
2272 // block to be the intersection of all previous locksets.
2273 // FIXME: By keeping the intersection, we may output more errors in future
2274 // for a lock which is not in the intersection, but was in the union. We
2275 // may want to also keep the union in future. As an example, let's say
2276 // the intersection contains Mutex L, and the union contains L and M.
2277 // Later we unlock M. At this point, we would output an error because we
2278 // never locked M; although the real error is probably that we forgot to
2279 // lock M on all code paths. Conversely, let's say that later we lock M.
2280 // In this case, we should compare against the intersection instead of the
2281 // union because the real error is probably that we forgot to unlock M on
2283 bool LocksetInitialized = false;
2284 llvm::SmallVector<CFGBlock*, 8> SpecialBlocks;
2285 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
2286 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
2288 // if *PI -> CurrBlock is a back edge
2289 if (*PI == 0 || !VisitedBlocks.alreadySet(*PI))
2292 int PrevBlockID = (*PI)->getBlockID();
2293 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2295 // Ignore edges from blocks that can't return.
2296 if ((*PI)->hasNoReturnElement() || !PrevBlockInfo->Reachable)
2299 // Okay, we can reach this block from the entry.
2300 CurrBlockInfo->Reachable = true;
2302 // If the previous block ended in a 'continue' or 'break' statement, then
2303 // a difference in locksets is probably due to a bug in that block, rather
2304 // than in some other predecessor. In that case, keep the other
2305 // predecessor's lockset.
2306 if (const Stmt *Terminator = (*PI)->getTerminator()) {
2307 if (isa<ContinueStmt>(Terminator) || isa<BreakStmt>(Terminator)) {
2308 SpecialBlocks.push_back(*PI);
2314 FactSet PrevLockset;
2315 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
2317 if (!LocksetInitialized) {
2318 CurrBlockInfo->EntrySet = PrevLockset;
2319 LocksetInitialized = true;
2321 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2322 CurrBlockInfo->EntryLoc,
2323 LEK_LockedSomePredecessors);
2327 // Skip rest of block if it's not reachable.
2328 if (!CurrBlockInfo->Reachable)
2331 // Process continue and break blocks. Assume that the lockset for the
2332 // resulting block is unaffected by any discrepancies in them.
2333 for (unsigned SpecialI = 0, SpecialN = SpecialBlocks.size();
2334 SpecialI < SpecialN; ++SpecialI) {
2335 CFGBlock *PrevBlock = SpecialBlocks[SpecialI];
2336 int PrevBlockID = PrevBlock->getBlockID();
2337 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2339 if (!LocksetInitialized) {
2340 CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
2341 LocksetInitialized = true;
2343 // Determine whether this edge is a loop terminator for diagnostic
2344 // purposes. FIXME: A 'break' statement might be a loop terminator, but
2345 // it might also be part of a switch. Also, a subsequent destructor
2346 // might add to the lockset, in which case the real issue might be a
2347 // double lock on the other path.
2348 const Stmt *Terminator = PrevBlock->getTerminator();
2349 bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
2351 FactSet PrevLockset;
2352 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet,
2353 PrevBlock, CurrBlock);
2355 // Do not update EntrySet.
2356 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2357 PrevBlockInfo->ExitLoc,
2358 IsLoop ? LEK_LockedSomeLoopIterations
2359 : LEK_LockedSomePredecessors,
2364 BuildLockset LocksetBuilder(this, *CurrBlockInfo);
2366 // Visit all the statements in the basic block.
2367 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
2368 BE = CurrBlock->end(); BI != BE; ++BI) {
2369 switch (BI->getKind()) {
2370 case CFGElement::Statement: {
2371 const CFGStmt *CS = cast<CFGStmt>(&*BI);
2372 LocksetBuilder.Visit(const_cast<Stmt*>(CS->getStmt()));
2375 // Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
2376 case CFGElement::AutomaticObjectDtor: {
2377 const CFGAutomaticObjDtor *AD = cast<CFGAutomaticObjDtor>(&*BI);
2378 CXXDestructorDecl *DD = const_cast<CXXDestructorDecl*>(
2379 AD->getDestructorDecl(AC.getASTContext()));
2380 if (!DD->hasAttrs())
2383 // Create a dummy expression,
2384 VarDecl *VD = const_cast<VarDecl*>(AD->getVarDecl());
2385 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue,
2386 AD->getTriggerStmt()->getLocEnd());
2387 LocksetBuilder.handleCall(&DRE, DD);
2394 CurrBlockInfo->ExitSet = LocksetBuilder.FSet;
2396 // For every back edge from CurrBlock (the end of the loop) to another block
2397 // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
2398 // the one held at the beginning of FirstLoopBlock. We can look up the
2399 // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
2400 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
2401 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
2403 // if CurrBlock -> *SI is *not* a back edge
2404 if (*SI == 0 || !VisitedBlocks.alreadySet(*SI))
2407 CFGBlock *FirstLoopBlock = *SI;
2408 CFGBlockInfo *PreLoop = &BlockInfo[FirstLoopBlock->getBlockID()];
2409 CFGBlockInfo *LoopEnd = &BlockInfo[CurrBlockID];
2410 intersectAndWarn(LoopEnd->ExitSet, PreLoop->EntrySet,
2412 LEK_LockedSomeLoopIterations,
2417 CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
2418 CFGBlockInfo *Final = &BlockInfo[CFGraph->getExit().getBlockID()];
2420 // Skip the final check if the exit block is unreachable.
2421 if (!Final->Reachable)
2424 // FIXME: Should we call this function for all blocks which exit the function?
2425 intersectAndWarn(Initial->EntrySet, Final->ExitSet,
2427 LEK_LockedAtEndOfFunction,
2428 LEK_NotLockedAtEndOfFunction,
2432 } // end anonymous namespace
2436 namespace thread_safety {
2438 /// \brief Check a function's CFG for thread-safety violations.
2440 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2441 /// at the end of each block, and issue warnings for thread safety violations.
2442 /// Each block in the CFG is traversed exactly once.
2443 void runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2444 ThreadSafetyHandler &Handler) {
2445 ThreadSafetyAnalyzer Analyzer(Handler);
2446 Analyzer.runAnalysis(AC);
2449 /// \brief Helper function that returns a LockKind required for the given level
2451 LockKind getLockKindFromAccessKind(AccessKind AK) {
2456 return LK_Exclusive;
2458 llvm_unreachable("Unknown AccessKind");
2461 }} // end namespace clang::thread_safety