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-rw-r--r--compilerplugins/clang/oncevar.cxx414
1 files changed, 414 insertions, 0 deletions
diff --git a/compilerplugins/clang/oncevar.cxx b/compilerplugins/clang/oncevar.cxx
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+++ b/compilerplugins/clang/oncevar.cxx
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+/* -*- 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: */