119 lines
4 KiB
C++
119 lines
4 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#include <string>
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#include <iostream>
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#include "plugin.hxx"
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#include "compat.hxx"
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#include "clang/AST/CXXInheritance.h"
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// Idea from bubli. Check that the index variable in a for loop is able to cover the range
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// revealed by the terminating condition.
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// If not, we might end up in an endless loop, or just not process certain parts.
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namespace
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{
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class LoopVarTooSmall:
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public RecursiveASTVisitor<LoopVarTooSmall>, public loplugin::Plugin
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{
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public:
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explicit LoopVarTooSmall(InstantiationData const & data): Plugin(data) {}
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virtual void run() override {
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TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
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}
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bool VisitForStmt( const ForStmt* stmt );
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private:
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StringRef getFilename(SourceLocation loc);
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};
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StringRef LoopVarTooSmall::getFilename(SourceLocation loc)
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{
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SourceLocation spellingLocation = compiler.getSourceManager().getSpellingLoc(loc);
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StringRef name { compiler.getSourceManager().getFilename(spellingLocation) };
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return name;
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}
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bool LoopVarTooSmall::VisitForStmt( const ForStmt* stmt )
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{
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if (ignoreLocation( stmt ))
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return true;
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// ignore sal/ module for now
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StringRef aFileName = getFilename(stmt->getLocStart());
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if (aFileName.startswith(SRCDIR "/sal/")) {
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return true;
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}
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const Stmt* initStmt = stmt->getInit();
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if (!initStmt || !isa<DeclStmt>(initStmt))
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return true;
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const DeclStmt* declStmt = dyn_cast<DeclStmt>(initStmt);
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if (!declStmt->getDeclGroup().isSingleDecl())
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return true;
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const Decl* decl = declStmt->getSingleDecl();
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if (!decl || !isa<VarDecl>(decl))
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return true;
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const VarDecl* varDecl = dyn_cast<VarDecl>(decl);
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QualType qt = varDecl->getType();
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if (!qt->isIntegralType(compiler.getASTContext()))
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return true;
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uint64_t qt1BitWidth = compiler.getASTContext().getTypeSize(qt);
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if (!stmt->getCond() || !isa<BinaryOperator>(stmt->getCond()))
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return true;
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const BinaryOperator* binOp = dyn_cast<BinaryOperator>(stmt->getCond());
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if (binOp->getOpcode() != BO_LT && binOp->getOpcode() != BO_LE)
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return true;
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const Expr* binOpRHS = binOp->getRHS();
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// ignore complex expressions for now, promotion rules on conditions like "i < (size()+1)"
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// make it hard to guess at a correct type.
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if (isa<BinaryOperator>(binOpRHS) || isa<ParenExpr>(binOpRHS))
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return true;
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if (isa<ImplicitCastExpr>(binOpRHS)) {
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const ImplicitCastExpr* castExpr = dyn_cast<ImplicitCastExpr>(binOpRHS);
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binOpRHS = castExpr->getSubExpr();
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}
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QualType qt2 = binOpRHS->getType();
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if (!qt2->isIntegralType(compiler.getASTContext()))
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return true;
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// check for comparison with constants where the compiler just tends to give me the type as "int"
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llvm::APSInt aIntResult;
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uint64_t qt2BitWidth = compiler.getASTContext().getTypeSize(qt2);
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if (binOpRHS->EvaluateAsInt(aIntResult, compiler.getASTContext())) {
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if (aIntResult.getSExtValue() > 0 && aIntResult.getSExtValue() < 1<<7) {
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qt2BitWidth = 8;
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} else if (aIntResult.getSExtValue() > 0 && aIntResult.getSExtValue() < 1<<15) {
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qt2BitWidth = 16;
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} else if (aIntResult.getSExtValue() > 0 && aIntResult.getSExtValue() < 1L<<31) {
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qt2BitWidth = 32;
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}
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}
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if (qt1BitWidth < qt2BitWidth) {
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report(
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DiagnosticsEngine::Warning,
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"loop index type %0 is narrower than length type %1",
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stmt->getInit()->getLocStart())
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<< qt << qt2 << stmt->getInit()->getSourceRange();
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//stmt->getCond()->dump();
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}
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return true;
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}
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loplugin::Plugin::Registration< LoopVarTooSmall > X("loopvartoosmall");
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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