1 //== BodyFarm.cpp - Factory for conjuring up fake bodies ----------*- 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 // BodyFarm is a factory for creating faux implementations for functions/methods
11 // for analysis purposes.
13 //===----------------------------------------------------------------------===//
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/ExprObjC.h"
20 #include "clang/Analysis/CodeInjector.h"
21 #include "llvm/ADT/StringSwitch.h"
23 using namespace clang;
25 //===----------------------------------------------------------------------===//
26 // Helper creation functions for constructing faux ASTs.
27 //===----------------------------------------------------------------------===//
29 static bool isDispatchBlock(QualType Ty) {
30 // Is it a block pointer?
31 const BlockPointerType *BPT = Ty->getAs<BlockPointerType>();
35 // Check if the block pointer type takes no arguments and
37 const FunctionProtoType *FT =
38 BPT->getPointeeType()->getAs<FunctionProtoType>();
39 return FT && FT->getReturnType()->isVoidType() && FT->getNumParams() == 0;
45 ASTMaker(ASTContext &C) : C(C) {}
47 /// Create a new BinaryOperator representing a simple assignment.
48 BinaryOperator *makeAssignment(const Expr *LHS, const Expr *RHS, QualType Ty);
50 /// Create a new BinaryOperator representing a comparison.
51 BinaryOperator *makeComparison(const Expr *LHS, const Expr *RHS,
52 BinaryOperator::Opcode Op);
54 /// Create a new compound stmt using the provided statements.
55 CompoundStmt *makeCompound(ArrayRef<Stmt*>);
57 /// Create a new DeclRefExpr for the referenced variable.
58 DeclRefExpr *makeDeclRefExpr(const VarDecl *D);
60 /// Create a new UnaryOperator representing a dereference.
61 UnaryOperator *makeDereference(const Expr *Arg, QualType Ty);
63 /// Create an implicit cast for an integer conversion.
64 Expr *makeIntegralCast(const Expr *Arg, QualType Ty);
66 /// Create an implicit cast to a builtin boolean type.
67 ImplicitCastExpr *makeIntegralCastToBoolean(const Expr *Arg);
69 // Create an implicit cast for lvalue-to-rvaluate conversions.
70 ImplicitCastExpr *makeLvalueToRvalue(const Expr *Arg, QualType Ty);
72 /// Create an Objective-C bool literal.
73 ObjCBoolLiteralExpr *makeObjCBool(bool Val);
75 /// Create an Objective-C ivar reference.
76 ObjCIvarRefExpr *makeObjCIvarRef(const Expr *Base, const ObjCIvarDecl *IVar);
78 /// Create a Return statement.
79 ReturnStmt *makeReturn(const Expr *RetVal);
86 BinaryOperator *ASTMaker::makeAssignment(const Expr *LHS, const Expr *RHS,
88 return new (C) BinaryOperator(const_cast<Expr*>(LHS), const_cast<Expr*>(RHS),
89 BO_Assign, Ty, VK_RValue,
90 OK_Ordinary, SourceLocation(), FPOptions());
93 BinaryOperator *ASTMaker::makeComparison(const Expr *LHS, const Expr *RHS,
94 BinaryOperator::Opcode Op) {
95 assert(BinaryOperator::isLogicalOp(Op) ||
96 BinaryOperator::isComparisonOp(Op));
97 return new (C) BinaryOperator(const_cast<Expr*>(LHS),
98 const_cast<Expr*>(RHS),
100 C.getLogicalOperationType(),
102 OK_Ordinary, SourceLocation(), FPOptions());
105 CompoundStmt *ASTMaker::makeCompound(ArrayRef<Stmt *> Stmts) {
106 return new (C) CompoundStmt(C, Stmts, SourceLocation(), SourceLocation());
109 DeclRefExpr *ASTMaker::makeDeclRefExpr(const VarDecl *D) {
111 DeclRefExpr::Create(/* Ctx = */ C,
112 /* QualifierLoc = */ NestedNameSpecifierLoc(),
113 /* TemplateKWLoc = */ SourceLocation(),
114 /* D = */ const_cast<VarDecl*>(D),
115 /* RefersToEnclosingVariableOrCapture = */ false,
116 /* NameLoc = */ SourceLocation(),
117 /* T = */ D->getType(),
118 /* VK = */ VK_LValue);
122 UnaryOperator *ASTMaker::makeDereference(const Expr *Arg, QualType Ty) {
123 return new (C) UnaryOperator(const_cast<Expr*>(Arg), UO_Deref, Ty,
124 VK_LValue, OK_Ordinary, SourceLocation());
127 ImplicitCastExpr *ASTMaker::makeLvalueToRvalue(const Expr *Arg, QualType Ty) {
128 return ImplicitCastExpr::Create(C, Ty, CK_LValueToRValue,
129 const_cast<Expr*>(Arg), nullptr, VK_RValue);
132 Expr *ASTMaker::makeIntegralCast(const Expr *Arg, QualType Ty) {
133 if (Arg->getType() == Ty)
134 return const_cast<Expr*>(Arg);
136 return ImplicitCastExpr::Create(C, Ty, CK_IntegralCast,
137 const_cast<Expr*>(Arg), nullptr, VK_RValue);
140 ImplicitCastExpr *ASTMaker::makeIntegralCastToBoolean(const Expr *Arg) {
141 return ImplicitCastExpr::Create(C, C.BoolTy, CK_IntegralToBoolean,
142 const_cast<Expr*>(Arg), nullptr, VK_RValue);
145 ObjCBoolLiteralExpr *ASTMaker::makeObjCBool(bool Val) {
146 QualType Ty = C.getBOOLDecl() ? C.getBOOLType() : C.ObjCBuiltinBoolTy;
147 return new (C) ObjCBoolLiteralExpr(Val, Ty, SourceLocation());
150 ObjCIvarRefExpr *ASTMaker::makeObjCIvarRef(const Expr *Base,
151 const ObjCIvarDecl *IVar) {
152 return new (C) ObjCIvarRefExpr(const_cast<ObjCIvarDecl*>(IVar),
153 IVar->getType(), SourceLocation(),
154 SourceLocation(), const_cast<Expr*>(Base),
155 /*arrow=*/true, /*free=*/false);
159 ReturnStmt *ASTMaker::makeReturn(const Expr *RetVal) {
160 return new (C) ReturnStmt(SourceLocation(), const_cast<Expr*>(RetVal),
164 //===----------------------------------------------------------------------===//
165 // Creation functions for faux ASTs.
166 //===----------------------------------------------------------------------===//
168 typedef Stmt *(*FunctionFarmer)(ASTContext &C, const FunctionDecl *D);
170 /// Create a fake body for dispatch_once.
171 static Stmt *create_dispatch_once(ASTContext &C, const FunctionDecl *D) {
172 // Check if we have at least two parameters.
173 if (D->param_size() != 2)
176 // Check if the first parameter is a pointer to integer type.
177 const ParmVarDecl *Predicate = D->getParamDecl(0);
178 QualType PredicateQPtrTy = Predicate->getType();
179 const PointerType *PredicatePtrTy = PredicateQPtrTy->getAs<PointerType>();
182 QualType PredicateTy = PredicatePtrTy->getPointeeType();
183 if (!PredicateTy->isIntegerType())
186 // Check if the second parameter is the proper block type.
187 const ParmVarDecl *Block = D->getParamDecl(1);
188 QualType Ty = Block->getType();
189 if (!isDispatchBlock(Ty))
192 // Everything checks out. Create a fakse body that checks the predicate,
193 // sets it, and calls the block. Basically, an AST dump of:
195 // void dispatch_once(dispatch_once_t *predicate, dispatch_block_t block) {
196 // if (!*predicate) {
204 // (1) Create the call.
205 DeclRefExpr *DR = M.makeDeclRefExpr(Block);
206 ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty);
207 CallExpr *CE = new (C) CallExpr(C, ICE, None, C.VoidTy, VK_RValue,
210 // (2) Create the assignment to the predicate.
212 IntegerLiteral::Create(C, llvm::APInt(C.getTypeSize(C.IntTy), (uint64_t) 1),
213 C.IntTy, SourceLocation());
217 M.makeLvalueToRvalue(
218 M.makeDeclRefExpr(Predicate), PredicateQPtrTy),
220 M.makeIntegralCast(IL, PredicateTy),
223 // (3) Create the compound statement.
224 Stmt *Stmts[] = { B, CE };
225 CompoundStmt *CS = M.makeCompound(Stmts);
227 // (4) Create the 'if' condition.
228 ImplicitCastExpr *LValToRval =
229 M.makeLvalueToRvalue(
231 M.makeLvalueToRvalue(
232 M.makeDeclRefExpr(Predicate),
237 UnaryOperator *UO = new (C) UnaryOperator(LValToRval, UO_LNot, C.IntTy,
238 VK_RValue, OK_Ordinary,
241 // (5) Create the 'if' statement.
242 IfStmt *If = new (C) IfStmt(C, SourceLocation(), false, nullptr, nullptr,
247 /// Create a fake body for dispatch_sync.
248 static Stmt *create_dispatch_sync(ASTContext &C, const FunctionDecl *D) {
249 // Check if we have at least two parameters.
250 if (D->param_size() != 2)
253 // Check if the second parameter is a block.
254 const ParmVarDecl *PV = D->getParamDecl(1);
255 QualType Ty = PV->getType();
256 if (!isDispatchBlock(Ty))
259 // Everything checks out. Create a fake body that just calls the block.
260 // This is basically just an AST dump of:
262 // void dispatch_sync(dispatch_queue_t queue, void (^block)(void)) {
267 DeclRefExpr *DR = M.makeDeclRefExpr(PV);
268 ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty);
269 CallExpr *CE = new (C) CallExpr(C, ICE, None, C.VoidTy, VK_RValue,
274 static Stmt *create_OSAtomicCompareAndSwap(ASTContext &C, const FunctionDecl *D)
276 // There are exactly 3 arguments.
277 if (D->param_size() != 3)
281 // _Bool OSAtomicCompareAndSwapPtr(void *__oldValue,
283 // void * volatile *__theValue)
285 // if (oldValue == *theValue) {
286 // *theValue = newValue;
291 QualType ResultTy = D->getReturnType();
292 bool isBoolean = ResultTy->isBooleanType();
293 if (!isBoolean && !ResultTy->isIntegralType(C))
296 const ParmVarDecl *OldValue = D->getParamDecl(0);
297 QualType OldValueTy = OldValue->getType();
299 const ParmVarDecl *NewValue = D->getParamDecl(1);
300 QualType NewValueTy = NewValue->getType();
302 assert(OldValueTy == NewValueTy);
304 const ParmVarDecl *TheValue = D->getParamDecl(2);
305 QualType TheValueTy = TheValue->getType();
306 const PointerType *PT = TheValueTy->getAs<PointerType>();
309 QualType PointeeTy = PT->getPointeeType();
312 // Construct the comparison.
315 M.makeLvalueToRvalue(M.makeDeclRefExpr(OldValue), OldValueTy),
316 M.makeLvalueToRvalue(
318 M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy),
323 // Construct the body of the IfStmt.
328 M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy),
330 M.makeLvalueToRvalue(M.makeDeclRefExpr(NewValue), NewValueTy),
333 Expr *BoolVal = M.makeObjCBool(true);
334 Expr *RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal)
335 : M.makeIntegralCast(BoolVal, ResultTy);
336 Stmts[1] = M.makeReturn(RetVal);
337 CompoundStmt *Body = M.makeCompound(Stmts);
339 // Construct the else clause.
340 BoolVal = M.makeObjCBool(false);
341 RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal)
342 : M.makeIntegralCast(BoolVal, ResultTy);
343 Stmt *Else = M.makeReturn(RetVal);
345 /// Construct the If.
346 Stmt *If = new (C) IfStmt(C, SourceLocation(), false, nullptr, nullptr,
347 Comparison, Body, SourceLocation(), Else);
352 Stmt *BodyFarm::getBody(const FunctionDecl *D) {
353 D = D->getCanonicalDecl();
355 Optional<Stmt *> &Val = Bodies[D];
357 return Val.getValue();
361 if (D->getIdentifier() == nullptr)
364 StringRef Name = D->getName();
370 if (Name.startswith("OSAtomicCompareAndSwap") ||
371 Name.startswith("objc_atomicCompareAndSwap")) {
372 FF = create_OSAtomicCompareAndSwap;
375 FF = llvm::StringSwitch<FunctionFarmer>(Name)
376 .Case("dispatch_sync", create_dispatch_sync)
377 .Case("dispatch_once", create_dispatch_once)
381 if (FF) { Val = FF(C, D); }
382 else if (Injector) { Val = Injector->getBody(D); }
383 return Val.getValue();
386 static const ObjCIvarDecl *findBackingIvar(const ObjCPropertyDecl *Prop) {
387 const ObjCIvarDecl *IVar = Prop->getPropertyIvarDecl();
392 // When a readonly property is shadowed in a class extensions with a
393 // a readwrite property, the instance variable belongs to the shadowing
394 // property rather than the shadowed property. If there is no instance
395 // variable on a readonly property, check to see whether the property is
396 // shadowed and if so try to get the instance variable from shadowing
398 if (!Prop->isReadOnly())
401 auto *Container = cast<ObjCContainerDecl>(Prop->getDeclContext());
402 const ObjCInterfaceDecl *PrimaryInterface = nullptr;
403 if (auto *InterfaceDecl = dyn_cast<ObjCInterfaceDecl>(Container)) {
404 PrimaryInterface = InterfaceDecl;
405 } else if (auto *CategoryDecl = dyn_cast<ObjCCategoryDecl>(Container)) {
406 PrimaryInterface = CategoryDecl->getClassInterface();
407 } else if (auto *ImplDecl = dyn_cast<ObjCImplDecl>(Container)) {
408 PrimaryInterface = ImplDecl->getClassInterface();
413 // FindPropertyVisibleInPrimaryClass() looks first in class extensions, so it
414 // is guaranteed to find the shadowing property, if it exists, rather than
415 // the shadowed property.
416 auto *ShadowingProp = PrimaryInterface->FindPropertyVisibleInPrimaryClass(
417 Prop->getIdentifier(), Prop->getQueryKind());
418 if (ShadowingProp && ShadowingProp != Prop) {
419 IVar = ShadowingProp->getPropertyIvarDecl();
425 static Stmt *createObjCPropertyGetter(ASTContext &Ctx,
426 const ObjCPropertyDecl *Prop) {
427 // First, find the backing ivar.
428 const ObjCIvarDecl *IVar = findBackingIvar(Prop);
432 // Ignore weak variables, which have special behavior.
433 if (Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_weak)
436 // Look to see if Sema has synthesized a body for us. This happens in
437 // Objective-C++ because the return value may be a C++ class type with a
438 // non-trivial copy constructor. We can only do this if we can find the
439 // @synthesize for this property, though (or if we know it's been auto-
441 const ObjCImplementationDecl *ImplDecl =
442 IVar->getContainingInterface()->getImplementation();
444 for (const auto *I : ImplDecl->property_impls()) {
445 if (I->getPropertyDecl() != Prop)
448 if (I->getGetterCXXConstructor()) {
450 return M.makeReturn(I->getGetterCXXConstructor());
455 // Sanity check that the property is the same type as the ivar, or a
456 // reference to it, and that it is either an object pointer or trivially
458 if (!Ctx.hasSameUnqualifiedType(IVar->getType(),
459 Prop->getType().getNonReferenceType()))
461 if (!IVar->getType()->isObjCLifetimeType() &&
462 !IVar->getType().isTriviallyCopyableType(Ctx))
465 // Generate our body:
466 // return self->_ivar;
469 const VarDecl *selfVar = Prop->getGetterMethodDecl()->getSelfDecl();
475 M.makeLvalueToRvalue(
476 M.makeDeclRefExpr(selfVar),
480 if (!Prop->getType()->isReferenceType())
481 loadedIVar = M.makeLvalueToRvalue(loadedIVar, IVar->getType());
483 return M.makeReturn(loadedIVar);
486 Stmt *BodyFarm::getBody(const ObjCMethodDecl *D) {
487 // We currently only know how to synthesize property accessors.
488 if (!D->isPropertyAccessor())
491 D = D->getCanonicalDecl();
493 Optional<Stmt *> &Val = Bodies[D];
495 return Val.getValue();
498 const ObjCPropertyDecl *Prop = D->findPropertyDecl();
502 // For now, we only synthesize getters.
503 // Synthesizing setters would cause false negatives in the
504 // RetainCountChecker because the method body would bind the parameter
505 // to an instance variable, causing it to escape. This would prevent
506 // warning in the following common scenario:
508 // id foo = [[NSObject alloc] init];
509 // self.foo = foo; // We should warn that foo leaks here.
511 if (D->param_size() != 0)
514 Val = createObjCPropertyGetter(C, Prop);
516 return Val.getValue();