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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 17:32:43 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 17:32:43 +0000 |
commit | 6bf0a5cb5034a7e684dcc3500e841785237ce2dd (patch) | |
tree | a68f146d7fa01f0134297619fbe7e33db084e0aa /build/clang-plugin/VariableUsageHelpers.cpp | |
parent | Initial commit. (diff) | |
download | thunderbird-6bf0a5cb5034a7e684dcc3500e841785237ce2dd.tar.xz thunderbird-6bf0a5cb5034a7e684dcc3500e841785237ce2dd.zip |
Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | build/clang-plugin/VariableUsageHelpers.cpp | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/build/clang-plugin/VariableUsageHelpers.cpp b/build/clang-plugin/VariableUsageHelpers.cpp new file mode 100644 index 0000000000..abb9eb280f --- /dev/null +++ b/build/clang-plugin/VariableUsageHelpers.cpp @@ -0,0 +1,275 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "VariableUsageHelpers.h" +#include "Utils.h" + +std::vector<const Stmt *> getUsageAsRvalue(const ValueDecl *ValueDeclaration, + const FunctionDecl *FuncDecl) { + std::vector<const Stmt *> UsageStatements; + + // We check the function declaration has a body. + auto Body = FuncDecl->getBody(); + if (!Body) { + return std::vector<const Stmt *>(); + } + + // We build a Control Flow Graph (CFG) fron the body of the function + // declaration. + std::unique_ptr<CFG> StatementCFG = CFG::buildCFG( + FuncDecl, Body, &FuncDecl->getASTContext(), CFG::BuildOptions()); + + // We iterate through all the CFGBlocks, which basically means that we go over + // all the possible branches of the code and therefore cover all statements. + for (auto &Block : *StatementCFG) { + // We iterate through all the statements of the block. + for (auto &BlockItem : *Block) { + auto CFGStatement = BlockItem.getAs<CFGStmt>(); + if (!CFGStatement) { + continue; + } + + // FIXME: Right now this function/if chain is very basic and only covers + // the cases we need for escapesFunction() + if (auto BinOp = dyn_cast<BinaryOperator>(CFGStatement->getStmt())) { + // We only care about assignments. + if (BinOp->getOpcode() != BO_Assign) { + continue; + } + + // We want our declaration to be used on the right hand side of the + // assignment. + auto DeclRef = dyn_cast<DeclRefExpr>(IgnoreTrivials(BinOp->getRHS())); + if (!DeclRef) { + continue; + } + + if (DeclRef->getDecl() != ValueDeclaration) { + continue; + } + } else if (auto Return = dyn_cast<ReturnStmt>(CFGStatement->getStmt())) { + // We want our declaration to be used as the expression of the return + // statement. + auto DeclRef = dyn_cast_or_null<DeclRefExpr>( + IgnoreTrivials(Return->getRetValue())); + if (!DeclRef) { + continue; + } + + if (DeclRef->getDecl() != ValueDeclaration) { + continue; + } + } else { + continue; + } + + // We didn't early-continue, so we add the statement to the list. + UsageStatements.push_back(CFGStatement->getStmt()); + } + } + + return UsageStatements; +} + +// We declare our EscapesFunctionError enum to be an error code enum. +namespace std { +template <> struct is_error_code_enum<EscapesFunctionError> : true_type {}; +} // namespace std + +// We define the EscapesFunctionErrorCategory which contains the error messages +// corresponding to each enum variant. +namespace { +struct EscapesFunctionErrorCategory : std::error_category { + const char *name() const noexcept override; + std::string message(int ev) const override; +}; + +const char *EscapesFunctionErrorCategory::name() const noexcept { + return "escapes function"; +} + +std::string EscapesFunctionErrorCategory::message(int ev) const { + switch (static_cast<EscapesFunctionError>(ev)) { + case EscapesFunctionError::ConstructorDeclNotFound: + return "constructor declaration not found"; + + case EscapesFunctionError::FunctionDeclNotFound: + return "function declaration not found"; + + case EscapesFunctionError::FunctionIsBuiltin: + return "function is builtin"; + + case EscapesFunctionError::FunctionIsVariadic: + return "function is variadic"; + + case EscapesFunctionError::ExprNotInCall: + return "expression is not in call"; + + case EscapesFunctionError::NoParamForArg: + return "no parameter for argument"; + + case EscapesFunctionError::ArgAndParamNotPointers: + return "argument and parameter are not pointers"; + } +} + +const EscapesFunctionErrorCategory TheEscapesFunctionErrorCategory{}; +} // namespace + +std::error_code make_error_code(EscapesFunctionError e) { + return {static_cast<int>(e), TheEscapesFunctionErrorCategory}; +} + +ErrorOr<std::tuple<const Stmt *, const Decl *>> +escapesFunction(const Expr *Arg, const CXXConstructExpr *Construct) { + // We get the function declaration corresponding to the call. + auto CtorDecl = Construct->getConstructor(); + if (!CtorDecl) { + return EscapesFunctionError::ConstructorDeclNotFound; + } + + return escapesFunction(Arg, CtorDecl, Construct->getArgs(), + Construct->getNumArgs()); +} + +ErrorOr<std::tuple<const Stmt *, const Decl *>> +escapesFunction(const Expr *Arg, const CallExpr *Call) { + // We get the function declaration corresponding to the call. + auto FuncDecl = Call->getDirectCallee(); + if (!FuncDecl) { + return EscapesFunctionError::FunctionDeclNotFound; + } + + return escapesFunction(Arg, FuncDecl, Call->getArgs(), Call->getNumArgs()); +} + +ErrorOr<std::tuple<const Stmt *, const Decl *>> +escapesFunction(const Expr *Arg, const CXXOperatorCallExpr *OpCall) { + // We get the function declaration corresponding to the operator call. + auto FuncDecl = OpCall->getDirectCallee(); + if (!FuncDecl) { + return EscapesFunctionError::FunctionDeclNotFound; + } + + auto Args = OpCall->getArgs(); + auto NumArgs = OpCall->getNumArgs(); + // If this is an infix binary operator defined as a one-param method, we + // remove the first argument as it is inserted explicitly and creates a + // mismatch with the parameters of the method declaration. + if (isInfixBinaryOp(OpCall) && FuncDecl->getNumParams() == 1) { + Args++; + NumArgs--; + } + + return escapesFunction(Arg, FuncDecl, Args, NumArgs); +} + +ErrorOr<std::tuple<const Stmt *, const Decl *>> +escapesFunction(const Expr *Arg, const FunctionDecl *FuncDecl, + const Expr *const *Arguments, unsigned NumArgs) { + if (!NumArgs) { + return std::make_tuple((const Stmt *)nullptr, (const Decl *)nullptr); + } + + if (FuncDecl->getBuiltinID() != 0 || + ASTIsInSystemHeader(FuncDecl->getASTContext(), *FuncDecl)) { + return EscapesFunctionError::FunctionIsBuiltin; + } + + // FIXME: should probably be handled at some point, but it's too annoying + // for now. + if (FuncDecl->isVariadic()) { + return EscapesFunctionError::FunctionIsVariadic; + } + + // We find the argument number corresponding to the Arg expression. + unsigned ArgNum = 0; + for (unsigned i = 0; i < NumArgs; i++) { + if (IgnoreTrivials(Arg) == IgnoreTrivials(Arguments[i])) { + break; + } + ++ArgNum; + } + // If we don't find it, we early-return NoneType. + if (ArgNum >= NumArgs) { + return EscapesFunctionError::ExprNotInCall; + } + + // Now we get the associated parameter. + if (ArgNum >= FuncDecl->getNumParams()) { + return EscapesFunctionError::NoParamForArg; + } + auto Param = FuncDecl->getParamDecl(ArgNum); + + // We want both the argument and the parameter to be of pointer type. + // FIXME: this is enough for the DanglingOnTemporaryChecker, because the + // analysed methods only return pointers, but more cases should probably be + // handled when we want to use this function more broadly. + if ((!Arg->getType().getNonReferenceType()->isPointerType() && + Arg->getType().getNonReferenceType()->isBuiltinType()) || + (!Param->getType().getNonReferenceType()->isPointerType() && + Param->getType().getNonReferenceType()->isBuiltinType())) { + return EscapesFunctionError::ArgAndParamNotPointers; + } + + // We retrieve the usages of the parameter in the function. + auto Usages = getUsageAsRvalue(Param, FuncDecl); + + // For each usage, we check if it doesn't allow the parameter to escape the + // function scope. + for (auto Usage : Usages) { + // In the case of an assignment. + if (auto BinOp = dyn_cast<BinaryOperator>(Usage)) { + // We retrieve the declaration the parameter is assigned to. + auto DeclRef = dyn_cast<DeclRefExpr>(BinOp->getLHS()); + if (!DeclRef) { + continue; + } + + if (auto ParamDeclaration = dyn_cast<ParmVarDecl>(DeclRef->getDecl())) { + // This is the case where the parameter escapes through another + // parameter. + + // FIXME: for now we only care about references because we only detect + // trivial LHS with just a DeclRefExpr, and not more complex cases like: + // void func(Type* param1, Type** param2) { + // *param2 = param1; + // } + // This should be fixed when we have better/more helper functions to + // help deal with this kind of lvalue expressions. + if (!ParamDeclaration->getType()->isReferenceType()) { + continue; + } + + return std::make_tuple(Usage, (const Decl *)ParamDeclaration); + } else if (auto VarDeclaration = dyn_cast<VarDecl>(DeclRef->getDecl())) { + // This is the case where the parameter escapes through a global/static + // variable. + if (!VarDeclaration->hasGlobalStorage()) { + continue; + } + + return std::make_tuple(Usage, (const Decl *)VarDeclaration); + } else if (auto FieldDeclaration = + dyn_cast<FieldDecl>(DeclRef->getDecl())) { + // This is the case where the parameter escapes through a field. + + return std::make_tuple(Usage, (const Decl *)FieldDeclaration); + } + } else if (isa<ReturnStmt>(Usage)) { + // This is the case where the parameter escapes through the return value + // of the function. + if (!FuncDecl->getReturnType()->isPointerType() && + !FuncDecl->getReturnType()->isReferenceType()) { + continue; + } + + return std::make_tuple(Usage, (const Decl *)FuncDecl); + } + } + + // No early-return, this means that we haven't found any case of funciton + // escaping and that therefore the parameter remains in the function scope. + return std::make_tuple((const Stmt *)nullptr, (const Decl *)nullptr); +} |