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Diffstat (limited to 'clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp')
| -rw-r--r-- | clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp | 348 |
1 files changed, 0 insertions, 348 deletions
diff --git a/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp b/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp deleted file mode 100644 index 485308f..0000000 --- a/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp +++ /dev/null @@ -1,348 +0,0 @@ -//===- FactsGenerator.cpp - Lifetime Facts Generation -----------*- C++ -*-===// -// -// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. -// See https://llvm.org/LICENSE.txt for license information. -// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -// -//===----------------------------------------------------------------------===// - -#include "clang/Analysis/Analyses/LifetimeSafety/FactsGenerator.h" -#include "clang/Analysis/Analyses/LifetimeSafety/LifetimeAnnotations.h" -#include "clang/Analysis/Analyses/PostOrderCFGView.h" -#include "llvm/Support/TimeProfiler.h" - -namespace clang::lifetimes::internal { - -static bool isGslPointerType(QualType QT) { - if (const auto *RD = QT->getAsCXXRecordDecl()) { - // We need to check the template definition for specializations. - if (auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(RD)) - return CTSD->getSpecializedTemplate() - ->getTemplatedDecl() - ->hasAttr<PointerAttr>(); - return RD->hasAttr<PointerAttr>(); - } - return false; -} - -static bool isPointerType(QualType QT) { - return QT->isPointerOrReferenceType() || isGslPointerType(QT); -} -// Check if a type has an origin. -static bool hasOrigin(const Expr *E) { - return E->isGLValue() || isPointerType(E->getType()); -} - -static bool hasOrigin(const VarDecl *VD) { - return isPointerType(VD->getType()); -} - -/// Creates a loan for the storage path of a given declaration reference. -/// This function should be called whenever a DeclRefExpr represents a borrow. -/// \param DRE The declaration reference expression that initiates the borrow. -/// \return The new Loan on success, nullptr otherwise. -static const Loan *createLoan(FactManager &FactMgr, const DeclRefExpr *DRE) { - if (const auto *VD = dyn_cast<ValueDecl>(DRE->getDecl())) { - AccessPath Path(VD); - // The loan is created at the location of the DeclRefExpr. - return &FactMgr.getLoanMgr().addLoan(Path, DRE); - } - return nullptr; -} - -void FactsGenerator::run() { - llvm::TimeTraceScope TimeProfile("FactGenerator"); - // Iterate through the CFG blocks in reverse post-order to ensure that - // initializations and destructions are processed in the correct sequence. - for (const CFGBlock *Block : *AC.getAnalysis<PostOrderCFGView>()) { - CurrentBlockFacts.clear(); - for (unsigned I = 0; I < Block->size(); ++I) { - const CFGElement &Element = Block->Elements[I]; - if (std::optional<CFGStmt> CS = Element.getAs<CFGStmt>()) - Visit(CS->getStmt()); - else if (std::optional<CFGAutomaticObjDtor> DtorOpt = - Element.getAs<CFGAutomaticObjDtor>()) - handleDestructor(*DtorOpt); - } - FactMgr.addBlockFacts(Block, CurrentBlockFacts); - } -} - -void FactsGenerator::VisitDeclStmt(const DeclStmt *DS) { - for (const Decl *D : DS->decls()) - if (const auto *VD = dyn_cast<VarDecl>(D)) - if (hasOrigin(VD)) - if (const Expr *InitExpr = VD->getInit()) - killAndFlowOrigin(*VD, *InitExpr); -} - -void FactsGenerator::VisitDeclRefExpr(const DeclRefExpr *DRE) { - handleUse(DRE); - // For non-pointer/non-view types, a reference to the variable's storage - // is a borrow. We create a loan for it. - // For pointer/view types, we stick to the existing model for now and do - // not create an extra origin for the l-value expression itself. - - // TODO: A single origin for a `DeclRefExpr` for a pointer or view type is - // not sufficient to model the different levels of indirection. The current - // single-origin model cannot distinguish between a loan to the variable's - // storage and a loan to what it points to. A multi-origin model would be - // required for this. - if (!isPointerType(DRE->getType())) { - if (const Loan *L = createLoan(FactMgr, DRE)) { - OriginID ExprOID = FactMgr.getOriginMgr().getOrCreate(*DRE); - CurrentBlockFacts.push_back( - FactMgr.createFact<IssueFact>(L->ID, ExprOID)); - } - } -} - -void FactsGenerator::VisitCXXConstructExpr(const CXXConstructExpr *CCE) { - if (isGslPointerType(CCE->getType())) { - handleGSLPointerConstruction(CCE); - return; - } -} - -void FactsGenerator::VisitCXXMemberCallExpr(const CXXMemberCallExpr *MCE) { - // Specifically for conversion operators, - // like `std::string_view p = std::string{};` - if (isGslPointerType(MCE->getType()) && - isa<CXXConversionDecl>(MCE->getCalleeDecl())) { - // The argument is the implicit object itself. - handleFunctionCall(MCE, MCE->getMethodDecl(), - {MCE->getImplicitObjectArgument()}, - /*IsGslConstruction=*/true); - } - if (const CXXMethodDecl *Method = MCE->getMethodDecl()) { - // Construct the argument list, with the implicit 'this' object as the - // first argument. - llvm::SmallVector<const Expr *, 4> Args; - Args.push_back(MCE->getImplicitObjectArgument()); - Args.append(MCE->getArgs(), MCE->getArgs() + MCE->getNumArgs()); - - handleFunctionCall(MCE, Method, Args, /*IsGslConstruction=*/false); - } -} - -void FactsGenerator::VisitCallExpr(const CallExpr *CE) { - handleFunctionCall(CE, CE->getDirectCallee(), - {CE->getArgs(), CE->getNumArgs()}); -} - -void FactsGenerator::VisitCXXNullPtrLiteralExpr( - const CXXNullPtrLiteralExpr *N) { - /// TODO: Handle nullptr expr as a special 'null' loan. Uninitialized - /// pointers can use the same type of loan. - FactMgr.getOriginMgr().getOrCreate(*N); -} - -void FactsGenerator::VisitImplicitCastExpr(const ImplicitCastExpr *ICE) { - if (!hasOrigin(ICE)) - return; - // An ImplicitCastExpr node itself gets an origin, which flows from the - // origin of its sub-expression (after stripping its own parens/casts). - killAndFlowOrigin(*ICE, *ICE->getSubExpr()); -} - -void FactsGenerator::VisitUnaryOperator(const UnaryOperator *UO) { - if (UO->getOpcode() == UO_AddrOf) { - const Expr *SubExpr = UO->getSubExpr(); - // Taking address of a pointer-type expression is not yet supported and - // will be supported in multi-origin model. - if (isPointerType(SubExpr->getType())) - return; - // The origin of an address-of expression (e.g., &x) is the origin of - // its sub-expression (x). This fact will cause the dataflow analysis - // to propagate any loans held by the sub-expression's origin to the - // origin of this UnaryOperator expression. - killAndFlowOrigin(*UO, *SubExpr); - } -} - -void FactsGenerator::VisitReturnStmt(const ReturnStmt *RS) { - if (const Expr *RetExpr = RS->getRetValue()) { - if (hasOrigin(RetExpr)) { - OriginID OID = FactMgr.getOriginMgr().getOrCreate(*RetExpr); - CurrentBlockFacts.push_back(FactMgr.createFact<ReturnOfOriginFact>(OID)); - } - } -} - -void FactsGenerator::VisitBinaryOperator(const BinaryOperator *BO) { - if (BO->isAssignmentOp()) - handleAssignment(BO->getLHS(), BO->getRHS()); -} - -void FactsGenerator::VisitCXXOperatorCallExpr(const CXXOperatorCallExpr *OCE) { - // Assignment operators have special "kill-then-propagate" semantics - // and are handled separately. - if (OCE->isAssignmentOp() && OCE->getNumArgs() == 2) { - handleAssignment(OCE->getArg(0), OCE->getArg(1)); - return; - } - handleFunctionCall(OCE, OCE->getDirectCallee(), - {OCE->getArgs(), OCE->getNumArgs()}, - /*IsGslConstruction=*/false); -} - -void FactsGenerator::VisitCXXFunctionalCastExpr( - const CXXFunctionalCastExpr *FCE) { - // Check if this is a test point marker. If so, we are done with this - // expression. - if (handleTestPoint(FCE)) - return; - if (isGslPointerType(FCE->getType())) - killAndFlowOrigin(*FCE, *FCE->getSubExpr()); -} - -void FactsGenerator::VisitInitListExpr(const InitListExpr *ILE) { - if (!hasOrigin(ILE)) - return; - // For list initialization with a single element, like `View{...}`, the - // origin of the list itself is the origin of its single element. - if (ILE->getNumInits() == 1) - killAndFlowOrigin(*ILE, *ILE->getInit(0)); -} - -void FactsGenerator::VisitMaterializeTemporaryExpr( - const MaterializeTemporaryExpr *MTE) { - if (!hasOrigin(MTE)) - return; - // A temporary object's origin is the same as the origin of the - // expression that initializes it. - killAndFlowOrigin(*MTE, *MTE->getSubExpr()); -} - -void FactsGenerator::handleDestructor(const CFGAutomaticObjDtor &DtorOpt) { - /// TODO: Also handle trivial destructors (e.g., for `int` - /// variables) which will never have a CFGAutomaticObjDtor node. - /// TODO: Handle loans to temporaries. - /// TODO: Consider using clang::CFG::BuildOptions::AddLifetime to reuse the - /// lifetime ends. - const VarDecl *DestructedVD = DtorOpt.getVarDecl(); - if (!DestructedVD) - return; - // Iterate through all loans to see if any expire. - /// TODO(opt): Do better than a linear search to find loans associated with - /// 'DestructedVD'. - for (const Loan &L : FactMgr.getLoanMgr().getLoans()) { - const AccessPath &LoanPath = L.Path; - // Check if the loan is for a stack variable and if that variable - // is the one being destructed. - if (LoanPath.D == DestructedVD) - CurrentBlockFacts.push_back(FactMgr.createFact<ExpireFact>( - L.ID, DtorOpt.getTriggerStmt()->getEndLoc())); - } -} - -void FactsGenerator::handleGSLPointerConstruction(const CXXConstructExpr *CCE) { - assert(isGslPointerType(CCE->getType())); - if (CCE->getNumArgs() != 1) - return; - if (hasOrigin(CCE->getArg(0))) - killAndFlowOrigin(*CCE, *CCE->getArg(0)); - else - // This could be a new borrow. - handleFunctionCall(CCE, CCE->getConstructor(), - {CCE->getArgs(), CCE->getNumArgs()}, - /*IsGslConstruction=*/true); -} - -/// Checks if a call-like expression creates a borrow by passing a value to a -/// reference parameter, creating an IssueFact if it does. -/// \param IsGslConstruction True if this is a GSL construction where all -/// argument origins should flow to the returned origin. -void FactsGenerator::handleFunctionCall(const Expr *Call, - const FunctionDecl *FD, - ArrayRef<const Expr *> Args, - bool IsGslConstruction) { - // Ignore functions returning values with no origin. - if (!FD || !hasOrigin(Call)) - return; - auto IsArgLifetimeBound = [FD](unsigned I) -> bool { - const ParmVarDecl *PVD = nullptr; - if (const auto *Method = dyn_cast<CXXMethodDecl>(FD); - Method && Method->isInstance()) { - if (I == 0) - // For the 'this' argument, the attribute is on the method itself. - return implicitObjectParamIsLifetimeBound(Method); - if ((I - 1) < Method->getNumParams()) - // For explicit arguments, find the corresponding parameter - // declaration. - PVD = Method->getParamDecl(I - 1); - } else if (I < FD->getNumParams()) - // For free functions or static methods. - PVD = FD->getParamDecl(I); - return PVD ? PVD->hasAttr<clang::LifetimeBoundAttr>() : false; - }; - if (Args.empty()) - return; - bool killedSrc = false; - for (unsigned I = 0; I < Args.size(); ++I) - if (IsGslConstruction || IsArgLifetimeBound(I)) { - if (!killedSrc) { - killedSrc = true; - killAndFlowOrigin(*Call, *Args[I]); - } else - flowOrigin(*Call, *Args[I]); - } -} - -/// Checks if the expression is a `void("__lifetime_test_point_...")` cast. -/// If so, creates a `TestPointFact` and returns true. -bool FactsGenerator::handleTestPoint(const CXXFunctionalCastExpr *FCE) { - if (!FCE->getType()->isVoidType()) - return false; - - const auto *SubExpr = FCE->getSubExpr()->IgnoreParenImpCasts(); - if (const auto *SL = dyn_cast<StringLiteral>(SubExpr)) { - llvm::StringRef LiteralValue = SL->getString(); - const std::string Prefix = "__lifetime_test_point_"; - - if (LiteralValue.starts_with(Prefix)) { - StringRef Annotation = LiteralValue.drop_front(Prefix.length()); - CurrentBlockFacts.push_back( - FactMgr.createFact<TestPointFact>(Annotation)); - return true; - } - } - return false; -} - -void FactsGenerator::handleAssignment(const Expr *LHSExpr, - const Expr *RHSExpr) { - if (!hasOrigin(LHSExpr)) - return; - // Find the underlying variable declaration for the left-hand side. - if (const auto *DRE_LHS = - dyn_cast<DeclRefExpr>(LHSExpr->IgnoreParenImpCasts())) { - markUseAsWrite(DRE_LHS); - if (const auto *VD_LHS = dyn_cast<ValueDecl>(DRE_LHS->getDecl())) { - // Kill the old loans of the destination origin and flow the new loans - // from the source origin. - killAndFlowOrigin(*VD_LHS, *RHSExpr); - } - } -} - -// A DeclRefExpr will be treated as a use of the referenced decl. It will be -// checked for use-after-free unless it is later marked as being written to -// (e.g. on the left-hand side of an assignment). -void FactsGenerator::handleUse(const DeclRefExpr *DRE) { - if (isPointerType(DRE->getType())) { - UseFact *UF = FactMgr.createFact<UseFact>(DRE); - CurrentBlockFacts.push_back(UF); - assert(!UseFacts.contains(DRE)); - UseFacts[DRE] = UF; - } -} - -void FactsGenerator::markUseAsWrite(const DeclRefExpr *DRE) { - if (!isPointerType(DRE->getType())) - return; - assert(UseFacts.contains(DRE)); - UseFacts[DRE]->markAsWritten(); -} - -} // namespace clang::lifetimes::internal |