diff options
Diffstat (limited to '')
| -rw-r--r-- | compilerplugins/clang/unusedvarsglobal.cxx | 959 |
1 files changed, 959 insertions, 0 deletions
diff --git a/compilerplugins/clang/unusedvarsglobal.cxx b/compilerplugins/clang/unusedvarsglobal.cxx new file mode 100644 index 000000000..50ac67d40 --- /dev/null +++ b/compilerplugins/clang/unusedvarsglobal.cxx @@ -0,0 +1,959 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * 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/. + */ + +#if !defined _WIN32 //TODO, #include <sys/file.h> + +#include <cassert> +#include <string> +#include <iostream> +#include <fstream> +#include <unordered_set> +#include <vector> +#include <algorithm> +#include <sys/file.h> +#include <unistd.h> + +#include "config_clang.h" + +#include "plugin.hxx" +#include "compat.hxx" +#include "check.hxx" + +#include "clang/AST/ParentMapContext.h" + +/** +This performs two analyses: + (1) look for unused global vars + (2) look for global vars that are write-only +*/ + +namespace +{ +struct MyVarInfo +{ + const VarDecl* varDecl; + std::string fieldName; + std::string fieldType; + std::string sourceLocation; +}; +bool operator<(const MyVarInfo& lhs, const MyVarInfo& rhs) +{ + return std::tie(lhs.sourceLocation, lhs.fieldName) + < std::tie(rhs.sourceLocation, rhs.fieldName); +} + +// try to limit the voluminous output a little +static std::set<MyVarInfo> readFromSet; +static std::set<MyVarInfo> writeToSet; +static std::set<MyVarInfo> definitionSet; + +/** + * Wrap the different kinds of callable and callee objects in the clang AST so I can define methods that handle everything. + */ +class CallerWrapper +{ + const CallExpr* m_callExpr; + const CXXConstructExpr* m_cxxConstructExpr; + +public: + CallerWrapper(const CallExpr* callExpr) + : m_callExpr(callExpr) + , m_cxxConstructExpr(nullptr) + { + } + CallerWrapper(const CXXConstructExpr* cxxConstructExpr) + : m_callExpr(nullptr) + , m_cxxConstructExpr(cxxConstructExpr) + { + } + unsigned getNumArgs() const + { + return m_callExpr ? m_callExpr->getNumArgs() : m_cxxConstructExpr->getNumArgs(); + } + const Expr* getArg(unsigned i) const + { + return m_callExpr ? m_callExpr->getArg(i) : m_cxxConstructExpr->getArg(i); + } +}; +class CalleeWrapper +{ + const FunctionDecl* m_calleeFunctionDecl = nullptr; + const CXXConstructorDecl* m_cxxConstructorDecl = nullptr; + const FunctionProtoType* m_functionPrototype = nullptr; + +public: + explicit CalleeWrapper(const FunctionDecl* calleeFunctionDecl) + : m_calleeFunctionDecl(calleeFunctionDecl) + { + } + explicit CalleeWrapper(const CXXConstructExpr* cxxConstructExpr) + : m_cxxConstructorDecl(cxxConstructExpr->getConstructor()) + { + } + explicit CalleeWrapper(const FunctionProtoType* functionPrototype) + : m_functionPrototype(functionPrototype) + { + } + unsigned getNumParams() const + { + if (m_calleeFunctionDecl) + return m_calleeFunctionDecl->getNumParams(); + else if (m_cxxConstructorDecl) + return m_cxxConstructorDecl->getNumParams(); + else if (m_functionPrototype->param_type_begin() == m_functionPrototype->param_type_end()) + // FunctionProtoType will assert if we call getParamTypes() and it has no params + return 0; + else + return m_functionPrototype->getParamTypes().size(); + } + const QualType getParamType(unsigned i) const + { + if (m_calleeFunctionDecl) + return m_calleeFunctionDecl->getParamDecl(i)->getType(); + else if (m_cxxConstructorDecl) + return m_cxxConstructorDecl->getParamDecl(i)->getType(); + else + return m_functionPrototype->getParamTypes()[i]; + } + std::string getNameAsString() const + { + if (m_calleeFunctionDecl) + return m_calleeFunctionDecl->getNameAsString(); + else if (m_cxxConstructorDecl) + return m_cxxConstructorDecl->getNameAsString(); + else + return ""; + } + CXXMethodDecl const* getAsCXXMethodDecl() const + { + if (m_calleeFunctionDecl) + return dyn_cast<CXXMethodDecl>(m_calleeFunctionDecl); + return nullptr; + } +}; + +class UnusedVarsGlobal : public loplugin::FilteringPlugin<UnusedVarsGlobal> +{ +public: + explicit UnusedVarsGlobal(loplugin::InstantiationData const& data) + : FilteringPlugin(data) + { + } + + virtual void run() override; + + bool shouldVisitTemplateInstantiations() const { return true; } + bool shouldVisitImplicitCode() const { return true; } + + bool VisitVarDecl(const VarDecl*); + bool VisitDeclRefExpr(const DeclRefExpr*); + bool TraverseCXXMethodDecl(CXXMethodDecl*); + bool TraverseFunctionDecl(FunctionDecl*); + bool TraverseIfStmt(IfStmt*); + +private: + MyVarInfo niceName(const VarDecl*); + void checkIfReadFrom(const VarDecl* fieldDecl, const DeclRefExpr* declRefExpr); + void checkIfWrittenTo(const VarDecl* fieldDecl, const DeclRefExpr* declRefExpr); + bool isSomeKindOfZero(const Expr* arg); + bool checkForWriteWhenUsingCollectionType(const CXXMethodDecl* calleeMethodDecl); + bool IsPassedByNonConst(const VarDecl* fieldDecl, const Stmt* child, CallerWrapper callExpr, + CalleeWrapper calleeFunctionDecl); + llvm::Optional<CalleeWrapper> getCallee(CallExpr const*); + + // For reasons I do not understand, parentFunctionDecl() is not reliable, so + // we store the parent function on the way down the AST. + FunctionDecl* insideFunctionDecl = nullptr; + std::vector<VarDecl const*> insideConditionalCheckOfVarSet; +}; + +void UnusedVarsGlobal::run() +{ + TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); + + if (!isUnitTestMode()) + { + // dump all our output in one write call - this is to try and limit IO "crosstalk" between multiple processes + // writing to the same logfile + std::string output; + for (const MyVarInfo& s : readFromSet) + output += "read:\t" + s.sourceLocation + "\t" + s.fieldName + "\n"; + for (const MyVarInfo& s : writeToSet) + output += "write:\t" + s.sourceLocation + "\t" + s.fieldName + "\n"; + for (const MyVarInfo& s : definitionSet) + output += "definition:\t" + s.fieldName + "\t" + s.fieldType + "\t" + s.sourceLocation + + "\n"; + std::ofstream myfile; + myfile.open(WORKDIR "/loplugin.unusedvarsglobal.log", std::ios::app | std::ios::out); + myfile << output; + myfile.close(); + } + else + { + for (const MyVarInfo& s : readFromSet) + report(DiagnosticsEngine::Warning, "read", s.varDecl->getBeginLoc()); + for (const MyVarInfo& s : writeToSet) + report(DiagnosticsEngine::Warning, "write", s.varDecl->getBeginLoc()); + } +} + +MyVarInfo UnusedVarsGlobal::niceName(const VarDecl* varDecl) +{ + MyVarInfo aInfo; + aInfo.varDecl = varDecl; + + aInfo.fieldName = varDecl->getNameAsString(); + // sometimes the name (if it's an anonymous thing) contains the full path of the build folder, which we don't need + size_t idx = aInfo.fieldName.find(SRCDIR); + if (idx != std::string::npos) + { + aInfo.fieldName = aInfo.fieldName.replace(idx, strlen(SRCDIR), ""); + } + aInfo.fieldType = varDecl->getType().getAsString(); + + SourceLocation expansionLoc + = compiler.getSourceManager().getExpansionLoc(varDecl->getLocation()); + StringRef name = getFilenameOfLocation(expansionLoc); + aInfo.sourceLocation + = std::string(name.substr(strlen(SRCDIR) + 1)) + ":" + + std::to_string(compiler.getSourceManager().getSpellingLineNumber(expansionLoc)); + loplugin::normalizeDotDotInFilePath(aInfo.sourceLocation); + + return aInfo; +} + +bool UnusedVarsGlobal::VisitVarDecl(const VarDecl* varDecl) +{ + varDecl = varDecl->getCanonicalDecl(); + if (isa<ParmVarDecl>(varDecl)) + return true; + if (!varDecl->hasGlobalStorage()) + return true; + if (!varDecl->getLocation().isValid() || ignoreLocation(varDecl)) + return true; + // ignore stuff that forms part of the stable URE interface + if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(varDecl->getLocation()))) + return true; + + /** + If we have + const size_t NB_PRODUCTS = 3; + int DefaultProductDir[NB_PRODUCTS] = { 3, 3, 3 }; + clang will inline the constant "3" and never tell us that we are reading from NB_PRODUCTS, + so just ignore integer constants. + */ + auto varType = varDecl->getType(); + if (varType.isConstQualified() && varType->isIntegerType()) + return true; + + auto initExpr = varDecl->getAnyInitializer(); + if (initExpr && !isSomeKindOfZero(initExpr)) + writeToSet.insert(niceName(varDecl)); + + definitionSet.insert(niceName(varDecl)); + return true; +} + +bool UnusedVarsGlobal::VisitDeclRefExpr(const DeclRefExpr* declRefExpr) +{ + const Decl* decl = declRefExpr->getDecl(); + const VarDecl* varDecl = dyn_cast<VarDecl>(decl); + if (!varDecl) + return true; + if (isa<ParmVarDecl>(varDecl)) + return true; + if (!varDecl->hasGlobalStorage()) + return true; + varDecl = varDecl->getCanonicalDecl(); + if (!varDecl->getLocation().isValid() || ignoreLocation(varDecl)) + return true; + // ignore stuff that forms part of the stable URE interface + if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(varDecl->getLocation()))) + return true; + checkIfReadFrom(varDecl, declRefExpr); + checkIfWrittenTo(varDecl, declRefExpr); + return true; +} + +/** + Does the expression being used to initialise a field value evaluate to + the same as a default value? + */ +bool UnusedVarsGlobal::isSomeKindOfZero(const Expr* arg) +{ + assert(arg); + if (arg->isValueDependent()) + return false; + if (arg->getType().isNull()) + return false; + if (isa<CXXDefaultArgExpr>(arg)) + arg = dyn_cast<CXXDefaultArgExpr>(arg)->getExpr(); + arg = arg->IgnoreParenCasts(); + // ignore this, it seems to trigger an infinite recursion + if (isa<UnaryExprOrTypeTraitExpr>(arg)) + return false; + if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(arg)) + return cxxConstructExpr->getConstructor()->isDefaultConstructor(); + APSInt x1; + if (compat::EvaluateAsInt(arg, x1, compiler.getASTContext())) + return x1 == 0; + if (isa<CXXNullPtrLiteralExpr>(arg)) + return true; + if (isa<MaterializeTemporaryExpr>(arg)) + { + const CXXBindTemporaryExpr* strippedArg + = dyn_cast_or_null<CXXBindTemporaryExpr>(arg->IgnoreParenCasts()); + if (strippedArg) + { + auto temp = dyn_cast<CXXTemporaryObjectExpr>(strippedArg->getSubExpr()); + if (temp->getNumArgs() == 0) + { + if (loplugin::TypeCheck(temp->getType()) + .Class("OUString") + .Namespace("rtl") + .GlobalNamespace()) + return true; + if (loplugin::TypeCheck(temp->getType()) + .Class("OString") + .Namespace("rtl") + .GlobalNamespace()) + return true; + return false; + } + } + } + + // Get the expression contents. + // This helps us find params which are always initialised with something like "OUString()". + SourceManager& SM = compiler.getSourceManager(); + SourceLocation startLoc = arg->getBeginLoc(); + SourceLocation endLoc = arg->getEndLoc(); + const char* p1 = SM.getCharacterData(startLoc); + const char* p2 = SM.getCharacterData(endLoc); + if (!p1 || !p2 || (p2 - p1) < 0 || (p2 - p1) > 40) + return false; + unsigned n = Lexer::MeasureTokenLength(endLoc, SM, compiler.getLangOpts()); + std::string s(p1, p2 - p1 + n); + // strip linefeed and tab characters so they don't interfere with the parsing of the log file + std::replace(s.begin(), s.end(), '\r', ' '); + std::replace(s.begin(), s.end(), '\n', ' '); + std::replace(s.begin(), s.end(), '\t', ' '); + + // now normalize the value. For some params, like OUString, we can pass it as OUString() or "" and they are the same thing + if (s == "OUString()") + return true; + else if (s == "OString()") + return true; + return false; +} + +static char easytolower(char in) +{ + if (in <= 'Z' && in >= 'A') + return in - ('Z' - 'z'); + return in; +} + +bool startswith(const std::string& rStr, const char* pSubStr) +{ + return rStr.compare(0, strlen(pSubStr), pSubStr) == 0; +} + +bool UnusedVarsGlobal::TraverseCXXMethodDecl(CXXMethodDecl* cxxMethodDecl) +{ + auto copy2 = insideFunctionDecl; + insideFunctionDecl = cxxMethodDecl; + bool ret = RecursiveASTVisitor::TraverseCXXMethodDecl(cxxMethodDecl); + insideFunctionDecl = copy2; + return ret; +} + +bool UnusedVarsGlobal::TraverseFunctionDecl(FunctionDecl* functionDecl) +{ + auto copy2 = insideFunctionDecl; + insideFunctionDecl = functionDecl; + bool ret = RecursiveASTVisitor::TraverseFunctionDecl(functionDecl); + insideFunctionDecl = copy2; + return ret; +} + +bool UnusedVarsGlobal::TraverseIfStmt(IfStmt* ifStmt) +{ + VarDecl const* varDecl = nullptr; + Expr const* cond = ifStmt->getCond()->IgnoreParenImpCasts(); + + if (auto memberCallExpr = dyn_cast<CXXMemberCallExpr>(cond)) + { + if (auto cxxConvert = dyn_cast_or_null<CXXConversionDecl>(memberCallExpr->getMethodDecl())) + { + if (cxxConvert->getConversionType()->isBooleanType()) + if (auto declRefExpr = dyn_cast<DeclRefExpr>( + memberCallExpr->getImplicitObjectArgument()->IgnoreParenImpCasts())) + if ((varDecl = dyn_cast<VarDecl>(declRefExpr->getDecl()))) + insideConditionalCheckOfVarSet.push_back(varDecl); + } + } + else if (auto declRefExpr = dyn_cast<DeclRefExpr>(cond)) + { + if ((varDecl = dyn_cast<VarDecl>(declRefExpr->getDecl()))) + insideConditionalCheckOfVarSet.push_back(varDecl); + } + + bool ret = RecursiveASTVisitor::TraverseIfStmt(ifStmt); + if (varDecl) + insideConditionalCheckOfVarSet.pop_back(); + return ret; +} + +void UnusedVarsGlobal::checkIfReadFrom(const VarDecl* varDecl, const DeclRefExpr* declRefExpr) +{ + auto parentsRange = compiler.getASTContext().getParents(*declRefExpr); + const Stmt* child = declRefExpr; + const Stmt* parent + = parentsRange.begin() == parentsRange.end() ? nullptr : parentsRange.begin()->get<Stmt>(); + // walk up the tree until we find something interesting + bool bPotentiallyReadFrom = false; + bool bDump = false; + auto walkUp = [&]() { + child = parent; + auto parentsRange = compiler.getASTContext().getParents(*parent); + parent = parentsRange.begin() == parentsRange.end() ? nullptr + : parentsRange.begin()->get<Stmt>(); + }; + do + { + if (!parent) + { + // check if we're inside a CXXCtorInitializer or a VarDecl + auto parentsRange = compiler.getASTContext().getParents(*child); + if (parentsRange.begin() != parentsRange.end()) + { + const Decl* decl = parentsRange.begin()->get<Decl>(); + if (decl && (isa<CXXConstructorDecl>(decl) || isa<VarDecl>(decl))) + bPotentiallyReadFrom = true; + } + if (!bPotentiallyReadFrom) + return; + break; + } + if (isa<CXXReinterpretCastExpr>(parent)) + { + // once we see one of these, there is not much useful we can know + bPotentiallyReadFrom = true; + break; + } + else if (isa<CastExpr>(parent) || isa<MemberExpr>(parent) || isa<ParenExpr>(parent) + || isa<ParenListExpr>(parent) || isa<ArrayInitLoopExpr>(parent) + || isa<ExprWithCleanups>(parent)) + { + walkUp(); + } + else if (auto unaryOperator = dyn_cast<UnaryOperator>(parent)) + { + UnaryOperator::Opcode op = unaryOperator->getOpcode(); + if (declRefExpr->getType()->isArrayType() && op == UO_Deref) + { + // ignore, deref'ing an array does not count as a read + } + else if (op == UO_AddrOf || op == UO_Deref || op == UO_Plus || op == UO_Minus + || op == UO_Not || op == UO_LNot) + { + bPotentiallyReadFrom = true; + break; + } + /* The following are technically reads, but from a code-sense they're more of a write/modify, so + ignore them to find interesting fields that only modified, not usefully read: + UO_PreInc / UO_PostInc / UO_PreDec / UO_PostDec + But we still walk up in case the result of the expression is used in a read sense. + */ + walkUp(); + } + else if (auto caseStmt = dyn_cast<CaseStmt>(parent)) + { + bPotentiallyReadFrom = caseStmt->getLHS() == child || caseStmt->getRHS() == child; + break; + } + else if (auto ifStmt = dyn_cast<IfStmt>(parent)) + { + bPotentiallyReadFrom = ifStmt->getCond() == child; + break; + } + else if (auto doStmt = dyn_cast<DoStmt>(parent)) + { + bPotentiallyReadFrom = doStmt->getCond() == child; + break; + } + else if (auto arraySubscriptExpr = dyn_cast<ArraySubscriptExpr>(parent)) + { + if (arraySubscriptExpr->getIdx() == child) + { + bPotentiallyReadFrom = true; + break; + } + walkUp(); + } + else if (auto binaryOp = dyn_cast<BinaryOperator>(parent)) + { + BinaryOperator::Opcode op = binaryOp->getOpcode(); + const bool assignmentOp = op == BO_Assign || op == BO_MulAssign || op == BO_DivAssign + || op == BO_RemAssign || op == BO_AddAssign + || op == BO_SubAssign || op == BO_ShlAssign + || op == BO_ShrAssign || op == BO_AndAssign + || op == BO_XorAssign || op == BO_OrAssign; + if (binaryOp->getLHS() == child && assignmentOp) + break; + else + { + bPotentiallyReadFrom = true; + break; + } + } + else if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(parent)) + { + auto op = operatorCallExpr->getOperator(); + const bool assignmentOp = op == OO_Equal || op == OO_StarEqual || op == OO_SlashEqual + || op == OO_PercentEqual || op == OO_PlusEqual + || op == OO_MinusEqual || op == OO_LessLessEqual + || op == OO_AmpEqual || op == OO_CaretEqual + || op == OO_PipeEqual; + if (operatorCallExpr->getArg(0) == child && assignmentOp) + break; + else if (op == OO_GreaterGreaterEqual && operatorCallExpr->getArg(1) == child) + break; // this is a write-only call + else + { + bPotentiallyReadFrom = true; + break; + } + } + else if (auto cxxMemberCallExpr = dyn_cast<CXXMemberCallExpr>(parent)) + { + bool bWriteOnlyCall = false; + const CXXMethodDecl* callee = cxxMemberCallExpr->getMethodDecl(); + if (callee) + { + const Expr* tmp = dyn_cast<Expr>(child); + if (tmp->isBoundMemberFunction(compiler.getASTContext())) + { + tmp = dyn_cast<MemberExpr>(tmp)->getBase(); + } + if (cxxMemberCallExpr->getImplicitObjectArgument() == tmp) + { + // FIXME perhaps a better solution here would be some kind of SAL_PARAM_WRITEONLY attribute + // which we could scatter around. + std::string name = callee->getNameAsString(); + std::transform(name.begin(), name.end(), name.begin(), easytolower); + if (startswith(name, "emplace") || name == "insert" || name == "erase" + || name == "remove" || name == "remove_if" || name == "sort" + || name == "push_back" || name == "pop_back" || name == "push_front" + || name == "pop_front" || name == "reserve" || name == "resize" + || name == "reset" || name == "clear" || name == "fill") + // write-only modifications to collections + bWriteOnlyCall = true; + else if (name == "dispose" || name == "disposeAndClear" || name == "swap") + // we're abusing the write-only analysis here to look for fields which don't have anything useful + // being done to them, so we're ignoring things like std::vector::clear, std::vector::swap, + // and VclPtr::disposeAndClear + bWriteOnlyCall = true; + } + } + if (!bWriteOnlyCall) + bPotentiallyReadFrom = true; + break; + } + else if (auto callExpr = dyn_cast<CallExpr>(parent)) + { + bool bWriteOnlyCall = false; + // check for calls to ReadXXX(foo) type methods, where foo is write-only + auto callee = getCallee(callExpr); + if (callee) + { + // FIXME perhaps a better solution here would be some kind of SAL_PARAM_WRITEONLY attribute + // which we could scatter around. + std::string name = callee->getNameAsString(); + std::transform(name.begin(), name.end(), name.begin(), easytolower); + if (startswith(name, "read")) + // this is a write-only call + bWriteOnlyCall = true; + } + if (!bWriteOnlyCall) + bPotentiallyReadFrom = true; + break; + } + else if (isa<ReturnStmt>(parent) || isa<CXXConstructExpr>(parent) + || isa<ConditionalOperator>(parent) || isa<SwitchStmt>(parent) + || isa<DeclStmt>(parent) || isa<WhileStmt>(parent) || isa<CXXNewExpr>(parent) + || isa<ForStmt>(parent) || isa<InitListExpr>(parent) + || isa<CXXDependentScopeMemberExpr>(parent) || isa<UnresolvedMemberExpr>(parent) + || isa<MaterializeTemporaryExpr>(parent)) + { + bPotentiallyReadFrom = true; + break; + } + else if (isa<CXXDeleteExpr>(parent) || isa<UnaryExprOrTypeTraitExpr>(parent) + || isa<CXXUnresolvedConstructExpr>(parent) || isa<CompoundStmt>(parent) + || isa<LabelStmt>(parent) || isa<CXXForRangeStmt>(parent) + || isa<CXXTypeidExpr>(parent) || isa<DefaultStmt>(parent) + || isa<GCCAsmStmt>(parent) || isa<LambdaExpr>(parent) // TODO + || isa<CXXDefaultArgExpr>(parent) || isa<AtomicExpr>(parent) + || isa<VAArgExpr>(parent) || isa<DeclRefExpr>(parent) || isa<ConstantExpr>(parent) + || isa<SubstNonTypeTemplateParmExpr>(parent)) + { + break; + } + else + { + bPotentiallyReadFrom = true; + bDump = true; + break; + } + } while (true); + + if (bDump) + { + report(DiagnosticsEngine::Warning, "oh dear, what can the matter be?", + declRefExpr->getBeginLoc()) + << declRefExpr->getSourceRange(); + report(DiagnosticsEngine::Note, "parent over here", parent->getBeginLoc()) + << parent->getSourceRange(); + parent->dump(); + declRefExpr->dump(); + } + + if (bPotentiallyReadFrom) + readFromSet.insert(niceName(varDecl)); +} + +void UnusedVarsGlobal::checkIfWrittenTo(const VarDecl* varDecl, const DeclRefExpr* declRefExpr) +{ + // if we're inside a block that looks like + // if (varDecl) + // ... + // then writes to this field don't matter, because unless we find another write to this field, this field is dead + if (std::find(insideConditionalCheckOfVarSet.begin(), insideConditionalCheckOfVarSet.end(), + varDecl) + != insideConditionalCheckOfVarSet.end()) + return; + + auto parentsRange = compiler.getASTContext().getParents(*declRefExpr); + const Stmt* child = declRefExpr; + const Stmt* parent + = parentsRange.begin() == parentsRange.end() ? nullptr : parentsRange.begin()->get<Stmt>(); + // walk up the tree until we find something interesting + bool bPotentiallyWrittenTo = false; + bool bDump = false; + auto walkUp = [&]() { + child = parent; + auto parentsRange = compiler.getASTContext().getParents(*parent); + parent = parentsRange.begin() == parentsRange.end() ? nullptr + : parentsRange.begin()->get<Stmt>(); + }; + do + { + if (!parent) + { + // check if we have an expression like + // int& r = m_field; + auto parentsRange = compiler.getASTContext().getParents(*child); + if (parentsRange.begin() != parentsRange.end()) + { + auto varDecl = dyn_cast_or_null<VarDecl>(parentsRange.begin()->get<Decl>()); + // The isImplicit() call is to avoid triggering when we see the vardecl which is part of a for-range statement, + // which is of type 'T&&' and also an l-value-ref ? + if (varDecl && !varDecl->isImplicit() + && loplugin::TypeCheck(varDecl->getType()).LvalueReference().NonConst()) + { + bPotentiallyWrittenTo = true; + } + } + break; + } + if (isa<CXXReinterpretCastExpr>(parent)) + { + // once we see one of these, there is not much useful we can know + bPotentiallyWrittenTo = true; + break; + } + else if (isa<CastExpr>(parent) || isa<MemberExpr>(parent) || isa<ParenExpr>(parent) + || isa<ParenListExpr>(parent) || isa<ArrayInitLoopExpr>(parent) + || isa<ExprWithCleanups>(parent)) + { + walkUp(); + } + else if (auto unaryOperator = dyn_cast<UnaryOperator>(parent)) + { + UnaryOperator::Opcode op = unaryOperator->getOpcode(); + if (op == UO_AddrOf || op == UO_PostInc || op == UO_PostDec || op == UO_PreInc + || op == UO_PreDec) + { + bPotentiallyWrittenTo = true; + } + break; + } + else if (auto arraySubscriptExpr = dyn_cast<ArraySubscriptExpr>(parent)) + { + if (arraySubscriptExpr->getIdx() == child) + break; + walkUp(); + } + else if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(parent)) + { + auto callee = getCallee(operatorCallExpr); + if (callee) + { + // if calling a non-const operator on the field + auto calleeMethodDecl = callee->getAsCXXMethodDecl(); + if (calleeMethodDecl && operatorCallExpr->getArg(0) == child) + { + if (!calleeMethodDecl->isConst()) + bPotentiallyWrittenTo + = checkForWriteWhenUsingCollectionType(calleeMethodDecl); + } + else if (IsPassedByNonConst(varDecl, child, operatorCallExpr, *callee)) + { + bPotentiallyWrittenTo = true; + } + } + else + bPotentiallyWrittenTo = true; // conservative, could improve + break; + } + else if (auto cxxMemberCallExpr = dyn_cast<CXXMemberCallExpr>(parent)) + { + const CXXMethodDecl* calleeMethodDecl = cxxMemberCallExpr->getMethodDecl(); + if (calleeMethodDecl) + { + // if calling a non-const method on the field + const Expr* tmp = dyn_cast<Expr>(child); + if (tmp->isBoundMemberFunction(compiler.getASTContext())) + { + tmp = dyn_cast<MemberExpr>(tmp)->getBase(); + } + if (cxxMemberCallExpr->getImplicitObjectArgument() == tmp) + { + if (!calleeMethodDecl->isConst()) + bPotentiallyWrittenTo + = checkForWriteWhenUsingCollectionType(calleeMethodDecl); + break; + } + else if (IsPassedByNonConst(varDecl, child, cxxMemberCallExpr, + CalleeWrapper(calleeMethodDecl))) + bPotentiallyWrittenTo = true; + } + else + bPotentiallyWrittenTo = true; // can happen in templates + break; + } + else if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(parent)) + { + if (IsPassedByNonConst(varDecl, child, cxxConstructExpr, + CalleeWrapper(cxxConstructExpr))) + bPotentiallyWrittenTo = true; + break; + } + else if (auto callExpr = dyn_cast<CallExpr>(parent)) + { + auto callee = getCallee(callExpr); + if (callee) + { + if (IsPassedByNonConst(varDecl, child, callExpr, *callee)) + bPotentiallyWrittenTo = true; + } + else + bPotentiallyWrittenTo = true; // conservative, could improve + break; + } + else if (auto binaryOp = dyn_cast<BinaryOperator>(parent)) + { + BinaryOperator::Opcode op = binaryOp->getOpcode(); + const bool assignmentOp = op == BO_Assign || op == BO_MulAssign || op == BO_DivAssign + || op == BO_RemAssign || op == BO_AddAssign + || op == BO_SubAssign || op == BO_ShlAssign + || op == BO_ShrAssign || op == BO_AndAssign + || op == BO_XorAssign || op == BO_OrAssign; + if (assignmentOp) + { + if (binaryOp->getLHS() == child) + bPotentiallyWrittenTo = true; + else if (loplugin::TypeCheck(binaryOp->getLHS()->getType()) + .LvalueReference() + .NonConst()) + // if the LHS is a non-const reference, we could write to the field later on + bPotentiallyWrittenTo = true; + } + break; + } + else if (isa<ReturnStmt>(parent)) + { + if (insideFunctionDecl) + { + auto tc = loplugin::TypeCheck(insideFunctionDecl->getReturnType()); + if (tc.LvalueReference().NonConst()) + bPotentiallyWrittenTo = true; + } + break; + } + else if (isa<ConditionalOperator>(parent) || isa<SwitchStmt>(parent) + || isa<DeclStmt>(parent) || isa<WhileStmt>(parent) || isa<CXXNewExpr>(parent) + || isa<ForStmt>(parent) || isa<InitListExpr>(parent) + || isa<CXXDependentScopeMemberExpr>(parent) || isa<UnresolvedMemberExpr>(parent) + || isa<MaterializeTemporaryExpr>(parent) || isa<IfStmt>(parent) + || isa<DoStmt>(parent) || isa<CXXDeleteExpr>(parent) + || isa<UnaryExprOrTypeTraitExpr>(parent) || isa<CXXUnresolvedConstructExpr>(parent) + || isa<CompoundStmt>(parent) || isa<LabelStmt>(parent) + || isa<CXXForRangeStmt>(parent) || isa<CXXTypeidExpr>(parent) + || isa<DefaultStmt>(parent) || isa<GCCAsmStmt>(parent) || isa<ConstantExpr>(parent) + || isa<AtomicExpr>(parent) || isa<CXXDefaultArgExpr>(parent) + || isa<VAArgExpr>(parent) || isa<DeclRefExpr>(parent) + || isa<SubstNonTypeTemplateParmExpr>(parent) || isa<LambdaExpr>(parent)) // TODO + { + break; + } + else + { + bPotentiallyWrittenTo = true; + bDump = true; + break; + } + } while (true); + + if (bDump) + { + report(DiagnosticsEngine::Warning, "oh dear, what can the matter be? writtenTo=%0", + declRefExpr->getBeginLoc()) + << bPotentiallyWrittenTo << declRefExpr->getSourceRange(); + if (parent) + { + report(DiagnosticsEngine::Note, "parent over here", parent->getBeginLoc()) + << parent->getSourceRange(); + parent->dump(); + } + declRefExpr->dump(); + varDecl->getType()->dump(); + } + + if (bPotentiallyWrittenTo) + writeToSet.insert(niceName(varDecl)); +} + +// return true if this not a collection type, or if it is a collection type, and we might be writing to it +bool UnusedVarsGlobal::checkForWriteWhenUsingCollectionType(const CXXMethodDecl* calleeMethodDecl) +{ + auto const tc = loplugin::TypeCheck(calleeMethodDecl->getParent()); + bool listLike = false, setLike = false, mapLike = false, cssSequence = false; + if (tc.Class("deque").StdNamespace() || tc.Class("list").StdNamespace() + || tc.Class("queue").StdNamespace() || tc.Class("vector").StdNamespace()) + { + listLike = true; + } + else if (tc.Class("set").StdNamespace() || tc.Class("unordered_set").StdNamespace()) + { + setLike = true; + } + else if (tc.Class("map").StdNamespace() || tc.Class("unordered_map").StdNamespace()) + { + mapLike = true; + } + else if (tc.Class("Sequence") + .Namespace("uno") + .Namespace("star") + .Namespace("sun") + .Namespace("com") + .GlobalNamespace()) + { + cssSequence = true; + } + else + return true; + + if (calleeMethodDecl->isOverloadedOperator()) + { + auto oo = calleeMethodDecl->getOverloadedOperator(); + if (oo == OO_Equal) + return true; + // This is operator[]. We only care about things that add elements to the collection. + // if nothing modifies the size of the collection, then nothing useful + // is stored in it. + if (listLike) + return false; + return true; + } + + auto name = calleeMethodDecl->getName(); + if (listLike || setLike || mapLike) + { + if (name == "reserve" || name == "shrink_to_fit" || name == "clear" || name == "erase" + || name == "pop_back" || name == "pop_front" || name == "front" || name == "back" + || name == "data" || name == "remove" || name == "remove_if" || name == "unique" + || name == "sort" || name == "begin" || name == "end" || name == "rbegin" + || name == "rend" || name == "at" || name == "find" || name == "equal_range" + || name == "lower_bound" || name == "upper_bound") + return false; + } + if (cssSequence) + { + if (name == "getArray" || name == "begin" || name == "end") + return false; + } + + return true; +} + +bool UnusedVarsGlobal::IsPassedByNonConst(const VarDecl* varDecl, const Stmt* child, + CallerWrapper callExpr, CalleeWrapper calleeFunctionDecl) +{ + unsigned len = std::min(callExpr.getNumArgs(), calleeFunctionDecl.getNumParams()); + // if it's an array, passing it by value to a method typically means the + // callee takes a pointer and can modify the array + if (varDecl->getType()->isConstantArrayType()) + { + for (unsigned i = 0; i < len; ++i) + if (callExpr.getArg(i) == child) + if (loplugin::TypeCheck(calleeFunctionDecl.getParamType(i)).Pointer().NonConst()) + return true; + } + else + { + for (unsigned i = 0; i < len; ++i) + if (callExpr.getArg(i) == child) + if (loplugin::TypeCheck(calleeFunctionDecl.getParamType(i)) + .LvalueReference() + .NonConst()) + return true; + } + return false; +} + +llvm::Optional<CalleeWrapper> UnusedVarsGlobal::getCallee(CallExpr const* callExpr) +{ + FunctionDecl const* functionDecl = callExpr->getDirectCallee(); + if (functionDecl) + return CalleeWrapper(functionDecl); + + // Extract the functionprototype from a type + clang::Type const* calleeType = callExpr->getCallee()->getType().getTypePtr(); + if (auto pointerType = calleeType->getUnqualifiedDesugaredType()->getAs<clang::PointerType>()) + { + if (auto prototype = pointerType->getPointeeType() + ->getUnqualifiedDesugaredType() + ->getAs<FunctionProtoType>()) + { + return CalleeWrapper(prototype); + } + } + + return llvm::Optional<CalleeWrapper>(); +} + +loplugin::Plugin::Registration<UnusedVarsGlobal> X("unusedvarsglobal", false); +} + +#endif + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |