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Diffstat (limited to 'compilerplugins/clang/sequentialassign.cxx')
| -rw-r--r-- | compilerplugins/clang/sequentialassign.cxx | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/compilerplugins/clang/sequentialassign.cxx b/compilerplugins/clang/sequentialassign.cxx new file mode 100644 index 000000000..01172df17 --- /dev/null +++ b/compilerplugins/clang/sequentialassign.cxx @@ -0,0 +1,327 @@ +/* -*- 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" + +/** + This is a kind of simplified dead-store analysis. + + We are looking for patterns like: + Foo x = a; + x = b; + which can be simplified to + x = b + + or + Foo x = a; + x = f(x) + which can be simplified to + Foo x = f(a) + + TODO Improve this plugin to make it safer. We should really be checking the following + conditions inside the RHS of the second statement: + If the variable is having it's address taken, or a non-const method called on it, + on passed by non-const-ref. +*/ + +namespace +{ +//static bool startswith(const std::string& rStr, const char* pSubStr) { +// return rStr.compare(0, strlen(pSubStr), pSubStr) == 0; +//} +class SequentialAssign : public loplugin::FilteringPlugin<SequentialAssign> +{ +public: + explicit SequentialAssign(loplugin::InstantiationData const& data) + : FilteringPlugin(data) + { + } + + virtual void run() override + { + std::string fn(handler.getMainFileName()); + loplugin::normalizeDotDotInFilePath(fn); + // places where the existing code style just looks better + // TODO lots of these would be unnecessary if I taught the plugin + // to ignore vars which are assigned to repeatedly + if (fn == SRCDIR "/vcl/source/helper/commandinfoprovider.cxx" + || fn == SRCDIR "/basegfx/source/polygon/b2dpolygonclipper.cxx" + || fn == SRCDIR "/i18nlangtag/source/isolang/insys.cxx" + || fn == SRCDIR "/vcl/unx/generic/fontmanager/fontconfig.cxx" + || fn == SRCDIR "/svtools/source/filter/exportdialog.cxx" + || fn == SRCDIR "/svtools/source/control/ruler.cxx" + || fn == SRCDIR "/basic/qa/cppunit/test_scanner.cxx" + || fn == SRCDIR "/basic/source/uno/namecont.cxx" + || fn == SRCDIR "/test/source/sheet/xnamedrange.cxx" + || fn == SRCDIR "/i18npool/qa/cppunit/test_breakiterator.cxx" + || fn == SRCDIR "/i18npool/source/localedata/LocaleNode.cxx" + || fn == SRCDIR "/i18npool/source/transliteration/transliteration_Ignore.cxx" + || fn == SRCDIR "/i18npool/qa/cppunit/test_textsearch.cxx" + || fn == SRCDIR "/framework/source/jobs/jobdata.cxx" + || fn == SRCDIR "/framework/source/services/pathsettings.cxx" + || fn == SRCDIR "/xmloff/source/chart/SchXMLTools.cxx" + || fn == SRCDIR "/svx/source/tbxctrls/Palette.cxx" + || fn == SRCDIR "/svx/source/sdr/contact/objectcontactofpageview.cxx" + || fn == SRCDIR "/svx/source/form/fmservs.cxx" + || fn == SRCDIR "/svx/source/svdraw/svdograf.cxx" + || fn == SRCDIR "/svx/source/accessibility/AccessibleShape.cxx" + || fn == SRCDIR "/svx/source/fmcomp/fmgridcl.cxx" + || fn == SRCDIR "/chart2/source/tools/CharacterProperties.cxx" + || fn == SRCDIR "/svx/source/dialog/dialcontrol.cxx" + || fn == SRCDIR "/connectivity/source/commontools/TTableHelper.cxx" + || fn == SRCDIR "/svx/source/dialog/_bmpmask.cxx" + || fn == SRCDIR "/media/noel/disk2/libo4/cui/source/dialogs/SignSignatureLineDialog.cxx" + || fn == SRCDIR "/filter/source/msfilter/msdffimp.cxx" + || fn == SRCDIR "/cui/source/dialogs/SignSignatureLineDialog.cxx" + || fn == SRCDIR "/cui/source/dialogs/screenshotannotationdlg.cxx" + || fn == SRCDIR "/cui/source/options/optupdt.cxx" + || fn == SRCDIR "/dbaccess/source/ui/querydesign/querycontroller.cxx" + || fn == SRCDIR "/dbaccess/source/ui/dlg/DbAdminImpl.cxx" + || fn == SRCDIR "/dbaccess/source/ui/querydesign/JoinController.cxx" + || fn == SRCDIR "/dbaccess/source/ui/misc/TokenWriter.cxx" + || fn == SRCDIR "/dbaccess/source/ui/misc/TokenWriter.cxx" + || fn == SRCDIR "/dbaccess/source/ui/misc/dbsubcomponentcontroller.cxx" + || fn == SRCDIR "/dbaccess/source/core/api/querycomposer.cxx" + || fn == SRCDIR "/desktop/source/lib/init.cxx" + || fn == SRCDIR "/lotuswordpro/source/filter/lwpfribmark.cxx" + || fn == SRCDIR "/tools/qa/cppunit/test_color.cxx" + || fn == SRCDIR "/sc/qa/unit/ucalc.cxx" + || fn == SRCDIR "/sc/source/ui/view/printfun.cxx" + || fn == SRCDIR "/sc/source/ui/view/preview.cxx" + || fn == SRCDIR "/sw/source/core/doc/tblafmt.cxx" + || fn == SRCDIR "/sw/source/core/draw/dflyobj.cxx" + || fn == SRCDIR "/sw/source/core/doc/DocumentDrawModelManager.cxx" + || fn == SRCDIR "/sw/source/core/edit/edfcol.cxx" + || fn == SRCDIR "/sw/source/filter/ww8/ww8toolbar.cxx" + || fn == SRCDIR "/sw/source/ui/fldui/fldvar.cxx" + || fn == SRCDIR "/sw/source/filter/ww8/ww8atr.cxx" + || fn == SRCDIR "/sd/source/ui/accessibility/AccessiblePageShape.cxx" + || fn == SRCDIR "/xmlsecurity/source/xmlsec/nss/nssinitializer.cxx" + || fn == SRCDIR "/sd/source/ui/slidesorter/cache/SlsRequestFactory.cxx" + || fn == SRCDIR "/sd/source/ui/framework/configuration/ResourceId.cxx" + || fn == SRCDIR "/sd/source/filter/html/htmlex.cxx" + || fn == SRCDIR "/starmath/source/cfgitem.cxx" + || fn == SRCDIR "/ucb/source/ucp/ftp/ftpurl.cxx" + || fn == SRCDIR "/starmath/source/node.cxx" + || fn == SRCDIR "/starmath/source/starmathdatabase.cxx" + || fn == SRCDIR "/ucb/source/ucp/cmis/certvalidation_handler.cxx" + || fn == SRCDIR "/reportdesign/source/ui/inspection/GeometryHandler.cxx" + || fn == SRCDIR "/reportdesign/source/core/api/ReportDefinition.cxx" + || fn == SRCDIR "/test/source/table/tablerow.cxx" + || fn == SRCDIR "/basegfx/test/B2DHomMatrixTest.cxx" + || fn == SRCDIR "/comphelper/qa/unit/base64_test.cxx" + || fn == SRCDIR "/testtools/source/bridgetest/bridgetest.cxx" + || fn == SRCDIR "/comphelper/qa/string/test_string.cxx" + || fn == SRCDIR "/cppu/qa/test_unotype.cxx" + || fn == SRCDIR "/cppu/qa/cppumaker/test_cppumaker.cxx" + || fn == SRCDIR "/o3tl/qa/test-lru_map.cxx" || fn == SRCDIR "/svl/qa/unit/svl.cxx" + || fn == SRCDIR "/chart2/qa/extras/PivotChartTest.cxx" + || fn == SRCDIR "/chart2/qa/extras/chart2export.cxx" + || fn == SRCDIR "/writerfilter/qa/cppunittests/misc/misc.cxx" + || fn == SRCDIR "/sw/qa/extras/ww8export/ww8export.cxx" + || fn == SRCDIR "/sw/qa/extras/uiwriter/uiwriter.cxx") + return; + // inside ifdef + if (fn == SRCDIR "/vcl/source/filter/png/pngread.cxx" + || fn == SRCDIR "/vcl/source/window/syschild.cxx" + || fn == SRCDIR "/sal/osl/unx/security.cxx" + || fn == SRCDIR "/vcl/source/filter/png/pngwrite.cxx" + || fn == SRCDIR "/svtools/source/control/inettbc.cxx" + || fn == SRCDIR "/canvas/source/cairo/cairo_textlayout.cxx" + || fn == SRCDIR "/sal/qa/osl/file/osl_File.cxx") + return; + // taking address of variable + if (fn == SRCDIR "/vcl/unx/generic/dtrans/X11_selection.cxx") + return; + // other + if (fn == SRCDIR "/sc/source/core/tool/scmatrix.cxx" + || fn == SRCDIR "/sal/qa/rtl/oustringbuffer/test_oustringbuffer_assign.cxx") + return; + + TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); + } + + bool VisitCompoundStmt(CompoundStmt const*); + +private: + const VarDecl* findSimpleAssign(Stmt const*); + bool isSimpleRHS(Expr const*); + Expr const* ignore(Expr const*); + void checkForSecondAssign(Stmt const* stmt, VarDecl const* varDecl); +}; + +bool SequentialAssign::VisitCompoundStmt(CompoundStmt const* compoundStmt) +{ + if (ignoreLocation(compoundStmt)) + return true; + + auto it = compoundStmt->body_begin(); + while (true) + { + if (it == compoundStmt->body_end()) + break; + auto firstStmt = *it; + const VarDecl* foundVars = findSimpleAssign(firstStmt); + // reference types have slightly weird behaviour + if (!foundVars || foundVars->getType()->isReferenceType()) + { + ++it; + continue; + } + ++it; + if (it == compoundStmt->body_end()) + break; + checkForSecondAssign(*it, foundVars); + } + + return true; +} + +void SequentialAssign::checkForSecondAssign(Stmt const* stmt, VarDecl const* varDecl) +{ + if (auto exprCleanup = dyn_cast<ExprWithCleanups>(stmt)) + stmt = exprCleanup->getSubExpr(); + + if (auto operatorCall = dyn_cast<CXXOperatorCallExpr>(stmt)) + { + if (operatorCall->getOperator() == OO_Equal) + { + if (auto declRefExprLHS = dyn_cast<DeclRefExpr>(ignore(operatorCall->getArg(0)))) + if (declRefExprLHS->getDecl() == varDecl) + { + report(DiagnosticsEngine::Warning, + "simplify by merging with the preceding assignment", stmt->getBeginLoc()) + << stmt->getSourceRange(); + } + } + return; + } + + if (auto binaryOp = dyn_cast<BinaryOperator>(stmt)) + { + if (binaryOp->getOpcode() == BO_Assign) + { + if (auto declRefExpr = dyn_cast<DeclRefExpr>(ignore(binaryOp->getLHS()))) + if (declRefExpr->getDecl() == varDecl) + { + report(DiagnosticsEngine::Warning, + "simplify by merging with the preceding assignment", stmt->getBeginLoc()) + << stmt->getSourceRange(); + } + } + } +} + +const VarDecl* SequentialAssign::findSimpleAssign(Stmt const* stmt) +{ + if (auto declStmt = dyn_cast<DeclStmt>(stmt)) + if (declStmt->isSingleDecl()) + if (auto varDeclLHS = dyn_cast_or_null<VarDecl>(declStmt->getSingleDecl())) + { + if (varDeclLHS->getStorageDuration() == SD_Static) + return nullptr; + // if it's call-style init (e.g. OUString s("xxx")), we only treat + // it as simple if it only contains a variable in the call + // (e.g. OUString s(x)) + if (varDeclLHS->getInitStyle() == VarDecl::InitializationStyle::CallInit) + { + auto cxxConstructExpr + = dyn_cast<CXXConstructExpr>(ignore(varDeclLHS->getInit())); + if (cxxConstructExpr) + { + if (cxxConstructExpr->getNumArgs() == 0) + return varDeclLHS; + if (cxxConstructExpr->getNumArgs() > 1) + return nullptr; + if (!isa<DeclRefExpr>(ignore(cxxConstructExpr->getArg(0)))) + return nullptr; + } + } + if (auto init = varDeclLHS->getInit()) + if (isSimpleRHS(init)) + return varDeclLHS; + } + if (auto operatorCall = dyn_cast<CXXOperatorCallExpr>(stmt)) + if (operatorCall->getOperator() == OO_Equal) + if (auto declRefExprLHS = dyn_cast<DeclRefExpr>(ignore(operatorCall->getArg(0)))) + if (auto varDeclLHS = dyn_cast<VarDecl>(declRefExprLHS->getDecl())) + if (isSimpleRHS(operatorCall->getArg(1))) + return varDeclLHS; + if (auto binaryOp = dyn_cast<BinaryOperator>(stmt)) + if (binaryOp->getOpcode() == BO_Assign) + if (auto declRefExprLHS = dyn_cast<DeclRefExpr>(ignore(binaryOp->getLHS()))) + if (auto varDeclLHS = dyn_cast<VarDecl>(declRefExprLHS->getDecl())) + if (isSimpleRHS(binaryOp->getRHS())) + return varDeclLHS; + return nullptr; +} + +/** + Does the first statement have a relatively simply RHS we can inline into the second statement? +*/ +bool SequentialAssign::isSimpleRHS(Expr const* expr) +{ + expr = ignore(expr); + + // code like + // Point aCurPos = rGlyphs + // always has a CXXConstructExpr wrapping the RHS + if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(expr)) + if (cxxConstructExpr->getNumArgs() == 1) + expr = ignore(cxxConstructExpr->getArg(0)); + + if (!expr->isValueDependent() + && expr->isConstantInitializer(compiler.getASTContext(), false /*ForRef*/)) + return true; + if (isa<CXXMemberCallExpr>(expr)) + return false; + if (isa<CXXOperatorCallExpr>(expr)) + return false; + if (isa<UserDefinedLiteral>(expr)) + return true; + if (isa<CallExpr>(expr)) + return false; + if (isa<CastExpr>(expr)) + return false; + if (isa<ArraySubscriptExpr>(expr)) + return false; + if (isa<BinaryOperator>(expr)) + return false; + if (isa<ConditionalOperator>(expr)) + return false; + if (isa<UnaryOperator>(expr)) + return false; + if (isa<CXXNewExpr>(expr)) + return false; + if (auto memberExpr = dyn_cast<MemberExpr>(expr)) + return isSimpleRHS(memberExpr->getBase()); + + return true; +} + +Expr const* SequentialAssign::ignore(Expr const* expr) +{ + return expr->IgnoreImplicit()->IgnoreParens()->IgnoreImplicit(); +} + +// Off by default because of safety concerns, see TODO at top +loplugin::Plugin::Registration<SequentialAssign> X("sequentialassign", false); +} + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |