diff options
Diffstat (limited to 'compilerplugins/clang/oncevar.cxx')
| -rw-r--r-- | compilerplugins/clang/oncevar.cxx | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/compilerplugins/clang/oncevar.cxx b/compilerplugins/clang/oncevar.cxx new file mode 100644 index 000000000..44fcfa950 --- /dev/null +++ b/compilerplugins/clang/oncevar.cxx @@ -0,0 +1,414 @@ +/* -*- 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/. + */ + +#include <cassert> +#include <string> +#include <iostream> +#include <unordered_map> +#include <unordered_set> + +#include "plugin.hxx" +#include "check.hxx" +#include "config_clang.h" +#include "clang/AST/CXXInheritance.h" +#include "clang/AST/StmtVisitor.h" + +// Original idea from tml. +// Look for variables that are (a) initialised from zero or one constants. (b) only used in one spot. +// In which case, we might as well inline it. + +namespace +{ + +Expr const * lookThroughInitListExpr(Expr const * expr) { + if (auto const ile = dyn_cast<InitListExpr>(expr->IgnoreParenImpCasts())) { + if (ile->getNumInits() == 1) { + return ile->getInit(0); + } + } + return expr; +} + +class ConstantValueDependentExpressionVisitor: + public ConstStmtVisitor<ConstantValueDependentExpressionVisitor, bool> +{ + ASTContext const & context_; + +public: + ConstantValueDependentExpressionVisitor(ASTContext const & context): + context_(context) {} + + bool Visit(Stmt const * stmt) { + assert(isa<Expr>(stmt)); + auto const expr = cast<Expr>(stmt); + if (!expr->isValueDependent()) { + return expr->isEvaluatable(context_); + } + return ConstStmtVisitor::Visit(stmt); + } + + bool VisitParenExpr(ParenExpr const * expr) + { return Visit(expr->getSubExpr()); } + + bool VisitCastExpr(CastExpr const * expr) { + return Visit(expr->getSubExpr()); + } + + bool VisitUnaryOperator(UnaryOperator const * expr) + { return Visit(expr->getSubExpr()); } + + bool VisitBinaryOperator(BinaryOperator const * expr) { + return Visit(expr->getLHS()) && Visit(expr->getRHS()); + } + + bool VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr const *) { + return true; + } +}; + +class OnceVar: + public loplugin::FilteringPlugin<OnceVar> +{ +public: + explicit OnceVar(loplugin::InstantiationData const & data): FilteringPlugin(data) {} + + virtual void run() override { + // ignore some files with problematic macros + std::string fn(handler.getMainFileName()); + loplugin::normalizeDotDotInFilePath(fn); + // platform-specific stuff + if (fn == SRCDIR "/sal/osl/unx/thread.cxx" + || fn == SRCDIR "/sot/source/base/formats.cxx" + || fn == SRCDIR "/svl/source/config/languageoptions.cxx" + || fn == SRCDIR "/sfx2/source/appl/appdde.cxx" + || fn == SRCDIR "/configmgr/source/components.cxx" + || fn == SRCDIR "/embeddedobj/source/msole/oleembed.cxx") + return; + // some of this is necessary + if (loplugin::hasPathnamePrefix( fn, SRCDIR "/sal/qa/")) + return; + if (loplugin::hasPathnamePrefix( fn, SRCDIR "/comphelper/qa/")) + return; + // TODO need to check calls via function pointer + if (fn == SRCDIR "/i18npool/source/textconversion/textconversion_zh.cxx" + || fn == SRCDIR "/i18npool/source/localedata/localedata.cxx") + return; + // debugging stuff + if (fn == SRCDIR "/sc/source/core/data/dpcache.cxx" + || fn == SRCDIR "/sw/source/core/layout/dbg_lay.cxx" + || fn == SRCDIR "/sw/source/core/layout/ftnfrm.cxx") + return; + // TODO taking local reference to variable + if (fn == SRCDIR "/sc/source/filter/excel/xechart.cxx") + return; + // macros managing to generate to a valid warning + if (fn == SRCDIR "/solenv/bin/concat-deps.c") + return; + // TODO bug in the plugin + if (fn == SRCDIR "/vcl/unx/generic/app/saldisp.cxx") + return; + + TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); + + for (auto const & varDecl : maVarDeclSet) + { + if (maVarDeclToIgnoreSet.find(varDecl) != maVarDeclToIgnoreSet.end()) + continue; + int noUses = 0; + auto it = maVarUsesMap.find(varDecl); + if (it != maVarUsesMap.end()) + noUses = it->second; + if (noUses > 1) + continue; + report(DiagnosticsEngine::Warning, + "var used only once, should be inlined or declared const", + varDecl->getLocation()) + << varDecl->getSourceRange(); + if (it != maVarUsesMap.end()) + report(DiagnosticsEngine::Note, + "used here", + maVarUseSourceRangeMap[varDecl].getBegin()) + << maVarUseSourceRangeMap[varDecl]; + } + } + + bool VisitMemberExpr(MemberExpr const * expr) { + // ignore cases like: + // const OUString("xxx") xxx; + // rtl_something(xxx.pData); + // where we cannot inline the declaration. + if (isa<FieldDecl>(expr->getMemberDecl())) { + recordIgnore(expr); + } + return true; + } + + bool VisitUnaryOperator(UnaryOperator const * expr) { + // if we take the address of it, or we modify it, ignore it + UnaryOperator::Opcode op = expr->getOpcode(); + if (op == UO_AddrOf || op == UO_PreInc || op == UO_PostInc + || op == UO_PreDec || op == UO_PostDec) + { + recordIgnore(expr->getSubExpr()); + } + return true; + } + + bool VisitBinaryOperator(BinaryOperator const * expr) { + // if we assign it another value, or modify it, ignore it + BinaryOperator::Opcode op = expr->getOpcode(); + if (op == BO_Assign || op == BO_PtrMemD || op == BO_PtrMemI || 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) + { + recordIgnore(expr->getLHS()); + } + return true; + } + + bool VisitCallExpr(CallExpr const * expr) { + unsigned firstArg = 0; + if (auto const cmce = dyn_cast<CXXMemberCallExpr>(expr)) { + if (auto const e1 = cmce->getMethodDecl()) { + if (!(e1->isConst() || e1->isStatic())) { + recordIgnore(cmce->getImplicitObjectArgument()); + } + } else if (auto const e2 = dyn_cast<BinaryOperator>( + cmce->getCallee()->IgnoreParenImpCasts())) + { + switch (e2->getOpcode()) { + case BO_PtrMemD: + case BO_PtrMemI: + if (!e2->getRHS()->getType()->getAs<MemberPointerType>() + ->getPointeeType()->getAs<FunctionProtoType>() + ->isConst()) + { + recordIgnore(e2->getLHS()); + } + break; + default: + break; + } + } + } else if (auto const coce = dyn_cast<CXXOperatorCallExpr>(expr)) { + if (auto const cmd = dyn_cast_or_null<CXXMethodDecl>( + coce->getDirectCallee())) + { + if (!cmd->isStatic()) { + assert(coce->getNumArgs() != 0); + if (!cmd->isConst()) { + recordIgnore(coce->getArg(0)); + } + firstArg = 1; + } + } + } + // ignore those ones we are passing by reference + const FunctionDecl* calleeFunctionDecl = expr->getDirectCallee(); + if (calleeFunctionDecl) { + for (unsigned i = firstArg; i < expr->getNumArgs(); ++i) { + if (i < calleeFunctionDecl->getNumParams()) { + QualType qt { calleeFunctionDecl->getParamDecl(i)->getType() }; + if (loplugin::TypeCheck(qt).LvalueReference().NonConst()) { + recordIgnore(expr->getArg(i)); + } + if (loplugin::TypeCheck(qt).Pointer().NonConst()) { + recordIgnore(expr->getArg(i)); + } + } + } + } + return true; + } + + bool VisitCXXConstructExpr(CXXConstructExpr const * expr) { + // ignore those ones we are passing by reference + const CXXConstructorDecl* cxxConstructorDecl = expr->getConstructor(); + for (unsigned i = 0; i < expr->getNumArgs(); ++i) { + if (i < cxxConstructorDecl->getNumParams()) { + QualType qt { cxxConstructorDecl->getParamDecl(i)->getType() }; + if (loplugin::TypeCheck(qt).LvalueReference().NonConst()) { + recordIgnore(expr->getArg(i)); + } + if (loplugin::TypeCheck(qt).Pointer().NonConst()) { + recordIgnore(expr->getArg(i)); + } + } + } + return true; + } + + bool VisitDeclRefExpr( const DeclRefExpr* ); + bool VisitVarDecl( const VarDecl* ); + bool TraverseFunctionDecl( FunctionDecl* functionDecl ); + +private: + std::unordered_set<VarDecl const *> maVarDeclSet; + std::unordered_set<VarDecl const *> maVarDeclToIgnoreSet; + std::unordered_map<VarDecl const *, int> maVarUsesMap; + std::unordered_map<VarDecl const *, SourceRange> maVarUseSourceRangeMap; + + bool isConstantValueDependentExpression(Expr const * expr) { + return ConstantValueDependentExpressionVisitor(compiler.getASTContext()) + .Visit(expr); + } + + void recordIgnore(Expr const * expr) { + for (;;) { + expr = expr->IgnoreParenImpCasts(); + if (auto const e = dyn_cast<MemberExpr>(expr)) { + if (isa<FieldDecl>(e->getMemberDecl())) { + expr = e->getBase(); + continue; + } + } + if (auto const e = dyn_cast<ArraySubscriptExpr>(expr)) { + expr = e->getBase(); + continue; + } + if (auto const e = dyn_cast<BinaryOperator>(expr)) { + if (e->getOpcode() == BO_PtrMemD) { + expr = e->getLHS(); + continue; + } + } + break; + } + auto const dre = dyn_cast<DeclRefExpr>(expr); + if (dre == nullptr) { + return; + } + auto const var = dyn_cast<VarDecl>(dre->getDecl()); + if (var == nullptr) { + return; + } + maVarDeclToIgnoreSet.insert(var); + } +}; + +bool OnceVar::TraverseFunctionDecl( FunctionDecl* functionDecl ) +{ + // Ignore functions that contains #ifdef-ery, can be quite tricky + // to make useful changes when this plugin fires in such functions + if (containsPreprocessingConditionalInclusion( + functionDecl->getSourceRange())) + return true; + return RecursiveASTVisitor::TraverseFunctionDecl(functionDecl); +} + +bool OnceVar::VisitVarDecl( const VarDecl* varDecl ) +{ + if (ignoreLocation(varDecl)) { + return true; + } + if (auto const init = varDecl->getInit()) { + recordIgnore(lookThroughInitListExpr(init)); + } + if (varDecl->isExceptionVariable() || isa<ParmVarDecl>(varDecl)) { + return true; + } + // ignore stuff in header files (which should really not be there, but anyhow) + if (!compiler.getSourceManager().isInMainFile(varDecl->getLocation())) { + return true; + } + // Ignore macros like FD_ZERO + if (compiler.getSourceManager().isMacroBodyExpansion(varDecl->getBeginLoc())) { + return true; + } + if (varDecl->hasGlobalStorage()) { + return true; + } + auto const tc = loplugin::TypeCheck(varDecl->getType()); + if (!varDecl->getType().isCXX11PODType(compiler.getASTContext()) + && !tc.Class("OString").Namespace("rtl").GlobalNamespace() + && !tc.Class("OUString").Namespace("rtl").GlobalNamespace() + && !tc.Class("OStringBuffer").Namespace("rtl").GlobalNamespace() + && !tc.Class("OUStringBuffer").Namespace("rtl").GlobalNamespace() + && !tc.Class("Color").GlobalNamespace() + && !tc.Class("Pair").GlobalNamespace() + && !tc.Class("Point").GlobalNamespace() + && !tc.Class("Size").GlobalNamespace() + && !tc.Class("Range").GlobalNamespace() + && !tc.Class("Selection").GlobalNamespace() + && !tc.Class("Rectangle").Namespace("tools").GlobalNamespace()) + { + return true; + } + if (varDecl->getType()->isPointerType()) + return true; + // if it's declared const, ignore it, it's there to make the code easier to read + if (tc.Const()) + return true; + + if (!varDecl->hasInit()) + return true; + + // check for string or scalar literals + bool foundStringLiteral = false; + const Expr * initExpr = varDecl->getInit(); + if (auto e = dyn_cast<ExprWithCleanups>(initExpr)) { + initExpr = e->getSubExpr(); + } + if (isa<clang::StringLiteral>(initExpr)) { + foundStringLiteral = true; + } else if (auto constructExpr = dyn_cast<CXXConstructExpr>(initExpr)) { + if (constructExpr->getNumArgs() == 0) { + foundStringLiteral = true; // i.e., empty string + } else { + auto stringLit2 = dyn_cast<clang::StringLiteral>(constructExpr->getArg(0)); + foundStringLiteral = stringLit2 != nullptr; + } + } + if (!foundStringLiteral) { + auto const init = varDecl->getInit(); + if (!(init->isValueDependent() + ? isConstantValueDependentExpression(init) + : init->isConstantInitializer( + compiler.getASTContext(), false/*ForRef*/))) + { + return true; + } + } + + maVarDeclSet.insert(varDecl); + + return true; +} + +bool OnceVar::VisitDeclRefExpr( const DeclRefExpr* declRefExpr ) +{ + if (ignoreLocation(declRefExpr)) { + return true; + } + const Decl* decl = declRefExpr->getDecl(); + if (!isa<VarDecl>(decl) || isa<ParmVarDecl>(decl)) { + return true; + } + const VarDecl * varDecl = dyn_cast<VarDecl>(decl)->getCanonicalDecl(); + // ignore stuff in header files (which should really not be there, but anyhow) + if (!compiler.getSourceManager().isInMainFile(varDecl->getLocation())) { + return true; + } + + if (maVarUsesMap.find(varDecl) == maVarUsesMap.end()) { + maVarUsesMap[varDecl] = 1; + maVarUseSourceRangeMap[varDecl] = declRefExpr->getSourceRange(); + } else { + maVarUsesMap[varDecl]++; + } + + return true; +} + +loplugin::Plugin::Registration< OnceVar > X("oncevar", false); + +} + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |