1344 lines
51 KiB
C++
1344 lines
51 KiB
C++
/*
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* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2016 Cppcheck team.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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//---------------------------------------------------------------------------
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#include "checkunusedvar.h"
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#include "symboldatabase.h"
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#include <algorithm>
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#include <utility>
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//---------------------------------------------------------------------------
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// Register this check class (by creating a static instance of it)
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namespace {
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CheckUnusedVar instance;
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}
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static const struct CWE CWE563(563U); // Assignment to Variable without Use ('Unused Variable')
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/**
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* @brief This class is used create a list of variables within a function.
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*/
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class Variables {
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public:
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enum VariableType { standard, array, pointer, reference, pointerArray, referenceArray, pointerPointer, none };
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/** Store information about variable usage */
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class VariableUsage {
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public:
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explicit VariableUsage(const Variable *var = nullptr,
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VariableType type = standard,
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bool read = false,
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bool write = false,
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bool modified = false,
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bool allocateMemory = false) :
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_var(var),
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_lastAccess(var?var->nameToken():0),
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_type(type),
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_read(read),
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_write(write),
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_modified(modified),
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_allocateMemory(allocateMemory) {
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}
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/** variable is used.. set both read+write */
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void use(std::list<std::set<unsigned int> > & varReadInScope) {
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varReadInScope.back().insert(_var->declarationId());
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_read = true;
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_write = true;
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}
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/** is variable unused? */
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bool unused() const {
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return (_read == false && _write == false);
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}
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std::set<unsigned int> _aliases;
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std::set<const Scope*> _assignments;
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const Variable* _var;
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const Token* _lastAccess;
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VariableType _type;
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bool _read;
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bool _write;
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bool _modified; // read/modify/write
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bool _allocateMemory;
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};
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class ScopeGuard {
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public:
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ScopeGuard(Variables & guarded,
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bool insideLoop)
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:_guarded(guarded),
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_insideLoop(insideLoop) {
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_guarded.enterScope();
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}
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~ScopeGuard() {
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_guarded.leaveScope(_insideLoop);
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}
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private:
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/** No implementation */
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ScopeGuard();
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ScopeGuard& operator=(const ScopeGuard &);
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Variables & _guarded;
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bool _insideLoop;
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};
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void clear() {
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_varUsage.clear();
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}
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const std::map<unsigned int, VariableUsage> &varUsage() const {
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return _varUsage;
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}
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void addVar(const Variable *var, VariableType type, bool write_);
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void allocateMemory(unsigned int varid, const Token* tok);
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void read(unsigned int varid, const Token* tok);
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void readAliases(unsigned int varid, const Token* tok);
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void readAll(unsigned int varid, const Token* tok);
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void write(unsigned int varid, const Token* tok);
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void writeAliases(unsigned int varid, const Token* tok);
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void writeAll(unsigned int varid, const Token* tok);
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void use(unsigned int varid, const Token* tok);
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void modified(unsigned int varid, const Token* tok);
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VariableUsage *find(unsigned int varid);
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void alias(unsigned int varid1, unsigned int varid2, bool replace);
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void erase(unsigned int varid) {
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_varUsage.erase(varid);
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}
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void eraseAliases(unsigned int varid);
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void eraseAll(unsigned int varid);
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void clearAliases(unsigned int varid);
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ScopeGuard newScope(bool insideLoop) {
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return ScopeGuard(*this, insideLoop);
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}
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private:
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void enterScope();
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void leaveScope(bool insideLoop);
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std::map<unsigned int, VariableUsage> _varUsage;
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std::list<std::set<unsigned int> > _varAddedInScope;
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std::list<std::set<unsigned int> > _varReadInScope;
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};
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/**
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* Alias the 2 given variables. Either replace the existing aliases if
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* they exist or merge them. You would replace an existing alias when this
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* assignment is in the same scope as the previous assignment. You might
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* merge the aliases when this assignment is in a different scope from the
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* previous assignment depending on the relationship of the 2 scopes.
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*/
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void Variables::alias(unsigned int varid1, unsigned int varid2, bool replace)
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{
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VariableUsage *var1 = find(varid1);
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VariableUsage *var2 = find(varid2);
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if (!var1 || !var2)
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return;
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// alias to self
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if (varid1 == varid2) {
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var1->use(_varReadInScope);
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return;
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}
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if (replace) {
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// remove var1 from all aliases
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for (std::set<unsigned int>::const_iterator i = var1->_aliases.begin(); i != var1->_aliases.end(); ++i) {
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VariableUsage *temp = find(*i);
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if (temp)
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temp->_aliases.erase(var1->_var->declarationId());
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}
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// remove all aliases from var1
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var1->_aliases.clear();
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}
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// var1 gets all var2s aliases
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for (std::set<unsigned int>::const_iterator i = var2->_aliases.begin(); i != var2->_aliases.end(); ++i) {
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if (*i != varid1)
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var1->_aliases.insert(*i);
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}
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// var2 is an alias of var1
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var2->_aliases.insert(varid1);
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var1->_aliases.insert(varid2);
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if (var2->_type == Variables::pointer) {
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_varReadInScope.back().insert(varid2);
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var2->_read = true;
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}
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}
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void Variables::clearAliases(unsigned int varid)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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// remove usage from all aliases
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std::set<unsigned int>::const_iterator i;
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for (i = usage->_aliases.begin(); i != usage->_aliases.end(); ++i) {
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VariableUsage *temp = find(*i);
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if (temp)
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temp->_aliases.erase(usage->_var->declarationId());
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}
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// remove all aliases from usage
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usage->_aliases.clear();
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}
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}
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void Variables::eraseAliases(unsigned int varid)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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std::set<unsigned int>::const_iterator aliases;
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for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases)
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erase(*aliases);
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}
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}
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void Variables::eraseAll(unsigned int varid)
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{
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eraseAliases(varid);
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erase(varid);
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}
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void Variables::addVar(const Variable *var,
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VariableType type,
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bool write_)
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{
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if (var->declarationId() > 0) {
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_varAddedInScope.back().insert(var->declarationId());
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_varUsage.insert(std::make_pair(var->declarationId(), VariableUsage(var, type, false, write_, false)));
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}
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}
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void Variables::allocateMemory(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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usage->_allocateMemory = true;
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usage->_lastAccess = tok;
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}
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}
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void Variables::read(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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_varReadInScope.back().insert(varid);
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usage->_read = true;
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if (tok)
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usage->_lastAccess = tok;
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}
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}
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void Variables::readAliases(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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std::set<unsigned int>::iterator aliases;
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for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
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VariableUsage *aliased = find(*aliases);
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if (aliased) {
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_varReadInScope.back().insert(*aliases);
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aliased->_read = true;
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aliased->_lastAccess = tok;
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}
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}
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}
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}
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void Variables::readAll(unsigned int varid, const Token* tok)
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{
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read(varid, tok);
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readAliases(varid, tok);
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}
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void Variables::write(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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usage->_write = true;
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if (!usage->_var->isStatic() && !Token::simpleMatch(tok->next(), "= 0 ;"))
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usage->_read = false;
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usage->_lastAccess = tok;
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}
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}
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void Variables::writeAliases(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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std::set<unsigned int>::const_iterator aliases;
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for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
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VariableUsage *aliased = find(*aliases);
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if (aliased) {
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aliased->_write = true;
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aliased->_lastAccess = tok;
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}
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}
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}
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}
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void Variables::writeAll(unsigned int varid, const Token* tok)
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{
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write(varid, tok);
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writeAliases(varid, tok);
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}
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void Variables::use(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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usage->use(_varReadInScope);
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usage->_lastAccess = tok;
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std::set<unsigned int>::const_iterator aliases;
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for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
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VariableUsage *aliased = find(*aliases);
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if (aliased) {
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aliased->use(_varReadInScope);
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aliased->_lastAccess = tok;
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}
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}
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}
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}
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void Variables::modified(unsigned int varid, const Token* tok)
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{
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VariableUsage *usage = find(varid);
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if (usage) {
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usage->_modified = true;
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usage->_lastAccess = tok;
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std::set<unsigned int>::const_iterator aliases;
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for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases) {
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VariableUsage *aliased = find(*aliases);
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if (aliased) {
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aliased->_modified = true;
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aliased->_lastAccess = tok;
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}
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}
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}
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}
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Variables::VariableUsage *Variables::find(unsigned int varid)
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{
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if (varid) {
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std::map<unsigned int, VariableUsage>::iterator i = _varUsage.find(varid);
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if (i != _varUsage.end())
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return &i->second;
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}
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return 0;
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}
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void Variables::enterScope()
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{
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_varAddedInScope.push_back(std::set<unsigned int>());
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_varReadInScope.push_back(std::set<unsigned int>());
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}
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void Variables::leaveScope(bool insideLoop)
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{
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if (insideLoop) {
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// read variables are read again in subsequent run through loop
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std::set<unsigned int> const & currentVarReadInScope = _varReadInScope.back();
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for (std::set<unsigned int>::const_iterator readIter = currentVarReadInScope.begin();
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readIter != currentVarReadInScope.end();
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++readIter) {
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read(*readIter, nullptr);
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}
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}
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std::list<std::set<unsigned int> >::reverse_iterator reverseReadIter = _varReadInScope.rbegin();
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++reverseReadIter;
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if (reverseReadIter != _varReadInScope.rend()) {
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// Transfer read variables into previous scope
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std::set<unsigned int> const & currentVarAddedInScope = _varAddedInScope.back();
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std::set<unsigned int> & currentVarReadInScope = _varReadInScope.back();
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for (std::set<unsigned int>::const_iterator addedIter = currentVarAddedInScope.begin();
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addedIter != currentVarAddedInScope.end();
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++addedIter) {
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currentVarReadInScope.erase(*addedIter);
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}
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std::set<unsigned int> & previousVarReadInScope = *reverseReadIter;
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previousVarReadInScope.insert(currentVarReadInScope.begin(),
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currentVarReadInScope.end());
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}
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_varReadInScope.pop_back();
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_varAddedInScope.pop_back();
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}
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static const Token* doAssignment(Variables &variables, const Token *tok, bool dereference, const Scope *scope)
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{
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// a = a + b;
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if (Token::Match(tok, "%var% = %var% !!;") && tok->varId() == tok->tokAt(2)->varId()) {
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return tok->tokAt(2);
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}
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if (Token::Match(tok, "%var% %assign%") && tok->strAt(1) != "=")
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return tok->next();
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const Token* const tokOld = tok;
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// check for aliased variable
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const unsigned int varid1 = tok->varId();
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Variables::VariableUsage *var1 = variables.find(varid1);
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if (var1) {
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// jump behind '='
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tok = tok->next();
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while (!tok->isAssignmentOp()) {
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if (tok->varId())
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variables.read(tok->varId(), tok);
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tok = tok->next();
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}
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tok = tok->next();
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if (Token::Match(tok, "( const| struct|union| %type% * ) ( ("))
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tok = tok->link()->next();
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if (Token::Match(tok, "( [(<] const| struct|union| %type% *| [>)]"))
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tok = tok->next();
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if (Token::Match(tok, "(| &| %name%") ||
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(tok && Token::Match(tok->next(), "< const| struct|union| %type% *| > ( &| %name%"))) {
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bool addressOf = false;
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if (Token::Match(tok, "%var% ."))
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variables.use(tok->varId(), tok); // use = read + write
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// check for C style cast
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if (tok->str() == "(") {
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tok = tok->next();
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if (tok->str() == "const")
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tok = tok->next();
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if (Token::Match(tok, "struct|union"))
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tok = tok->next();
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while ((tok->isName() && tok->varId() == 0) || (tok->str() == "*") || (tok->str() == ")"))
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tok = tok->next();
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if (tok->str() == "&") {
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addressOf = true;
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tok = tok->next();
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} else if (tok->str() == "(") {
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tok = tok->next();
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if (tok->str() == "&") {
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addressOf = true;
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tok = tok->next();
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}
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} else if (Token::Match(tok, "%cop% %var%")) {
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variables.read(tok->next()->varId(), tok);
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}
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}
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// check for C++ style cast
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else if (tok->str().find("cast") != std::string::npos &&
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tok->strAt(1) == "<") {
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tok = tok->tokAt(2);
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if (tok->str() == "const")
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tok = tok->next();
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if (Token::Match(tok, "struct|union"))
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tok = tok->next();
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tok = tok->next();
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if (tok->str() == "*")
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tok = tok->next();
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tok = tok->tokAt(2);
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if (!tok)
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return tokOld;
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if (tok->str() == "&") {
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addressOf = true;
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tok = tok->next();
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}
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}
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// no cast, no ?
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else if (!Token::Match(tok, "%name% ?")) {
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if (tok->str() == "&") {
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addressOf = true;
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tok = tok->next();
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} else if (tok->str() == "new")
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return tokOld;
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}
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// check if variable is local
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unsigned int varid2 = tok->varId();
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const Variables::VariableUsage* var2 = variables.find(varid2);
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if (var2) { // local variable (alias or read it)
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if (var1->_type == Variables::pointer || var1->_type == Variables::pointerArray) {
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if (dereference)
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variables.read(varid2, tok);
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else {
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if (addressOf ||
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var2->_type == Variables::array ||
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var2->_type == Variables::pointer) {
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bool replace = true;
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// pointerArray => don't replace
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if (var1->_type == Variables::pointerArray)
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replace = false;
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// check if variable declared in same scope
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else if (scope == var1->_var->scope())
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replace = true;
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// not in same scope as declaration
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else {
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// no other assignment in this scope
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if (var1->_assignments.find(scope) == var1->_assignments.end() ||
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scope->type == Scope::eSwitch) {
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// nothing to replace
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if (var1->_assignments.empty())
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replace = false;
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// this variable has previous assignments
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else {
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/**
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* @todo determine if existing aliases should be replaced or merged
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*/
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replace = false;
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}
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}
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// assignment in this scope
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else {
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// replace when only one other assignment, merge them otherwise
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replace = (var1->_assignments.size() == 1);
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}
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}
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|
|
variables.alias(varid1, varid2, replace);
|
|
} else if (tok->strAt(1) == "?") {
|
|
if (var2->_type == Variables::reference)
|
|
variables.readAliases(varid2, tok);
|
|
else
|
|
variables.read(varid2, tok);
|
|
} else {
|
|
variables.readAll(varid2, tok);
|
|
}
|
|
}
|
|
} else if (var1->_type == Variables::reference) {
|
|
variables.alias(varid1, varid2, true);
|
|
} else {
|
|
if ((var2->_type == Variables::pointer || var2->_type == Variables::pointerArray) && tok->strAt(1) == "[")
|
|
variables.readAliases(varid2, tok);
|
|
|
|
variables.read(varid2, tok);
|
|
}
|
|
} else { // not a local variable (or an unsupported local variable)
|
|
if (var1->_type == Variables::pointer && !dereference) {
|
|
// check if variable declaration is in this scope
|
|
if (var1->_var->scope() == scope)
|
|
variables.clearAliases(varid1);
|
|
else {
|
|
// no other assignment in this scope
|
|
if (var1->_assignments.find(scope) == var1->_assignments.end()) {
|
|
/**
|
|
* @todo determine if existing aliases should be discarded
|
|
*/
|
|
}
|
|
|
|
// this assignment replaces the last assignment in this scope
|
|
else {
|
|
// aliased variables in a larger scope are not supported
|
|
// remove all aliases
|
|
variables.clearAliases(varid1);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
} else
|
|
tok = tokOld;
|
|
|
|
var1->_assignments.insert(scope);
|
|
}
|
|
|
|
// check for alias to struct member
|
|
// char c[10]; a.b = c;
|
|
else if (Token::Match(tok->tokAt(-2), "%name% .")) {
|
|
if (tok->tokAt(2) && tok->tokAt(2)->varId()) {
|
|
const unsigned int varid2 = tok->tokAt(2)->varId();
|
|
const Variables::VariableUsage *var2 = variables.find(varid2);
|
|
|
|
// struct member aliased to local variable
|
|
if (var2 && (var2->_type == Variables::array ||
|
|
var2->_type == Variables::pointer)) {
|
|
// erase aliased variable and all variables that alias it
|
|
// to prevent false positives
|
|
variables.eraseAll(varid2);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Possible pointer alias
|
|
else if (Token::Match(tok, "%name% = %name% ;")) {
|
|
const unsigned int varid2 = tok->tokAt(2)->varId();
|
|
const Variables::VariableUsage *var2 = variables.find(varid2);
|
|
if (var2 && (var2->_type == Variables::array ||
|
|
var2->_type == Variables::pointer)) {
|
|
variables.use(varid2,tok);
|
|
}
|
|
}
|
|
|
|
return tok;
|
|
}
|
|
|
|
static bool isPartOfClassStructUnion(const Token* tok)
|
|
{
|
|
for (; tok; tok = tok->previous()) {
|
|
if (tok->str() == "}" || tok->str() == ")")
|
|
tok = tok->link();
|
|
else if (tok->str() == "(")
|
|
return (false);
|
|
else if (tok->str() == "{") {
|
|
return (tok->strAt(-1) == "struct" || tok->strAt(-2) == "struct" || tok->strAt(-1) == "class" || tok->strAt(-2) == "class" || tok->strAt(-1) == "union" || tok->strAt(-2) == "union");
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Skip [ .. ]
|
|
static const Token * skipBrackets(const Token *tok)
|
|
{
|
|
while (tok && tok->str() == "[")
|
|
tok = tok->link()->next();
|
|
return tok;
|
|
}
|
|
|
|
|
|
// Skip [ .. ] . x
|
|
static const Token * skipBracketsAndMembers(const Token *tok)
|
|
{
|
|
while (tok) {
|
|
if (tok->str() == "[")
|
|
tok = tok->link()->next();
|
|
else if (Token::Match(tok, ". %name%"))
|
|
tok = tok->tokAt(2);
|
|
else
|
|
break;
|
|
}
|
|
return tok;
|
|
}
|
|
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Usage of function variables
|
|
//---------------------------------------------------------------------------
|
|
void CheckUnusedVar::checkFunctionVariableUsage_iterateScopes(const Scope* const scope, Variables& variables, bool insideLoop)
|
|
{
|
|
Variables::ScopeGuard scopeGuard=variables.newScope(insideLoop);
|
|
|
|
// Find declarations if the scope is executable..
|
|
if (scope->isExecutable()) {
|
|
// Find declarations
|
|
for (std::list<Variable>::const_iterator i = scope->varlist.begin(); i != scope->varlist.end(); ++i) {
|
|
if (i->isThrow() || i->isExtern())
|
|
continue;
|
|
Variables::VariableType type = Variables::none;
|
|
if (i->isArray() && (i->nameToken()->previous()->str() == "*" || i->nameToken()->strAt(-2) == "*"))
|
|
type = Variables::pointerArray;
|
|
else if (i->isArray() && i->nameToken()->previous()->str() == "&")
|
|
type = Variables::referenceArray;
|
|
else if (i->isArray())
|
|
type = Variables::array;
|
|
else if (i->isReference())
|
|
type = Variables::reference;
|
|
else if (i->nameToken()->previous()->str() == "*" && i->nameToken()->strAt(-2) == "*")
|
|
type = Variables::pointerPointer;
|
|
else if (i->isPointerToArray())
|
|
type = Variables::pointerPointer;
|
|
else if (i->isPointer())
|
|
type = Variables::pointer;
|
|
else if (_tokenizer->isC() ||
|
|
i->typeEndToken()->isStandardType() ||
|
|
isRecordTypeWithoutSideEffects(i->type()) ||
|
|
(i->isStlType() &&
|
|
!Token::Match(i->typeStartToken()->tokAt(2), "lock_guard|unique_lock|shared_ptr|unique_ptr|auto_ptr|shared_lock")))
|
|
type = Variables::standard;
|
|
if (type == Variables::none || isPartOfClassStructUnion(i->typeStartToken()))
|
|
continue;
|
|
const Token* defValTok = i->nameToken()->next();
|
|
if (Token::Match(i->nameToken()->previous(), "* %var% ) (")) // function pointer. Jump behind parameter list.
|
|
defValTok = defValTok->linkAt(1)->next();
|
|
for (; defValTok; defValTok = defValTok->next()) {
|
|
if (defValTok->str() == "[")
|
|
defValTok = defValTok->link();
|
|
else if (defValTok->str() == "(" || defValTok->str() == "{" || defValTok->str() == "=" || defValTok->str() == ":") {
|
|
variables.addVar(&*i, type, true);
|
|
break;
|
|
} else if (defValTok->str() == ";" || defValTok->str() == "," || defValTok->str() == ")") {
|
|
variables.addVar(&*i, type, i->isStatic());
|
|
break;
|
|
}
|
|
}
|
|
if (i->isArray() && i->isClass()) // Array of class/struct members. Initialized by ctor.
|
|
variables.write(i->declarationId(), i->nameToken());
|
|
if (i->isArray() && Token::Match(i->nameToken(), "%name% [ %var% ]")) // Array index variable read.
|
|
variables.read(i->nameToken()->tokAt(2)->varId(), i->nameToken());
|
|
|
|
if (defValTok && defValTok->str() == "=") {
|
|
if (defValTok->next() && defValTok->next()->str() == "{") {
|
|
for (const Token* tok = defValTok; tok && tok != defValTok->linkAt(1); tok = tok->next())
|
|
if (tok->varId()) // Variables used to initialize the array read.
|
|
variables.read(tok->varId(), i->nameToken());
|
|
} else
|
|
doAssignment(variables, i->nameToken(), false, scope);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check variable usage
|
|
const Token *tok;
|
|
if (scope->type == Scope::eFunction)
|
|
tok = scope->classStart->next();
|
|
else
|
|
tok = scope->classDef->next();
|
|
for (; tok && tok != scope->classEnd; tok = tok->next()) {
|
|
if (tok->str() == "for" || tok->str() == "while" || tok->str() == "do") {
|
|
for (std::list<Scope*>::const_iterator i = scope->nestedList.begin(); i != scope->nestedList.end(); ++i) {
|
|
if ((*i)->classDef == tok) { // Find associated scope
|
|
checkFunctionVariableUsage_iterateScopes(*i, variables, true); // Scan child scope
|
|
tok = (*i)->classStart->link();
|
|
break;
|
|
}
|
|
}
|
|
if (!tok)
|
|
break;
|
|
}
|
|
if (tok->str() == "{" && tok != scope->classStart && !tok->previous()->varId()) {
|
|
for (std::list<Scope*>::const_iterator i = scope->nestedList.begin(); i != scope->nestedList.end(); ++i) {
|
|
if ((*i)->classStart == tok) { // Find associated scope
|
|
checkFunctionVariableUsage_iterateScopes(*i, variables, false); // Scan child scope
|
|
tok = tok->link();
|
|
break;
|
|
}
|
|
}
|
|
if (!tok)
|
|
break;
|
|
}
|
|
|
|
if (Token::Match(tok, "asm ( %str% )")) {
|
|
variables.clear();
|
|
break;
|
|
}
|
|
if (Token::Match(tok, "goto|break")) { // #4447
|
|
variables.clear();
|
|
break;
|
|
}
|
|
|
|
// templates
|
|
if (tok->isName() && tok->str().back() == '>') {
|
|
// TODO: This is a quick fix to handle when constants are used
|
|
// as template parameters. Try to handle this better, perhaps
|
|
// only remove constants.
|
|
variables.clear();
|
|
}
|
|
|
|
// bailout when for_each is used
|
|
if (Token::Match(tok, "%name% (") && Token::simpleMatch(tok->linkAt(1), ") {") && !Token::Match(tok, "if|for|while|switch")) {
|
|
// does the name contain "for_each" or "foreach"?
|
|
std::string nameTok;
|
|
nameTok.resize(tok->str().size());
|
|
std::transform(tok->str().begin(), tok->str().end(), nameTok.begin(), ::tolower);
|
|
if (nameTok.find("foreach") != std::string::npos || nameTok.find("for_each") != std::string::npos) {
|
|
// bailout all variables in the body that are used more than once.
|
|
// TODO: there is no need to bailout if variable is only read or only written
|
|
std::set<unsigned int> varid;
|
|
const Token * const endTok = tok->linkAt(1)->linkAt(1);
|
|
for (const Token *tok2 = endTok->link(); tok2 && tok2 != endTok; tok2 = tok2->next()) {
|
|
if (tok2->varId()) {
|
|
if (varid.find(tok2->varId()) == varid.end())
|
|
varid.insert(tok2->varId());
|
|
else
|
|
variables.erase(tok2->varId());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// C++11 std::for_each
|
|
// No warning should be written if a variable is first read and
|
|
// then written in the body.
|
|
else if (_tokenizer->isCPP() && Token::simpleMatch(tok, "for_each (") && Token::simpleMatch(tok->linkAt(1), ") ;")) {
|
|
const Token *end = tok->linkAt(1);
|
|
if (end->previous()->str() == "}") {
|
|
std::set<unsigned int> readvar;
|
|
for (const Token *body = end->linkAt(-1); body != end; body = body->next()) {
|
|
if (body->varId() == 0U)
|
|
continue;
|
|
if (!Token::simpleMatch(body->next(),"="))
|
|
readvar.insert(body->varId());
|
|
else if (readvar.find(body->varId()) != readvar.end())
|
|
variables.erase(body->varId());
|
|
}
|
|
}
|
|
}
|
|
|
|
else if (Token::Match(tok->previous(), "[;{}]")) {
|
|
for (const Token* tok2 = tok->next(); tok2; tok2 = tok2->next()) {
|
|
if (tok2->varId()) {
|
|
// Is this a variable declaration?
|
|
const Variable *var = tok2->variable();
|
|
if (!var || var->nameToken() != tok2)
|
|
continue;
|
|
|
|
// Mark template parameters used in declaration as use..
|
|
if (tok2->strAt(-1) == ">") {
|
|
for (const Token *tok3 = tok; tok3 != tok2; tok3 = tok3->next()) {
|
|
if (tok3->varId() > 0U)
|
|
variables.use(tok3->varId(), tok3);
|
|
}
|
|
}
|
|
|
|
// Skip variable declaration..
|
|
tok = tok2->next();
|
|
if (Token::Match(tok, "( %name% )")) // Simple initialization through copy ctor
|
|
tok = tok->next();
|
|
else if (Token::Match(tok, "= %var% ;")) { // Simple initialization
|
|
tok = tok->next();
|
|
if (!var->isReference())
|
|
variables.read(tok->varId(), tok);
|
|
} else if (var->typeEndToken()->str() == ">") // Be careful with types like std::vector
|
|
tok = tok->previous();
|
|
break;
|
|
} else if (Token::Match(tok2, "[;({=]"))
|
|
break;
|
|
}
|
|
}
|
|
// Freeing memory (not considered "using" the pointer if it was also allocated in this function)
|
|
if (Token::Match(tok, "free|g_free|kfree|vfree ( %var% )") ||
|
|
(_tokenizer->isCPP() && (Token::Match(tok, "delete %var% ;") || Token::Match(tok, "delete [ ] %var% ;")))) {
|
|
unsigned int varid = 0;
|
|
if (tok->str() != "delete") {
|
|
varid = tok->tokAt(2)->varId();
|
|
tok = tok->tokAt(3);
|
|
} else if (tok->strAt(1) == "[") {
|
|
varid = tok->tokAt(3)->varId();
|
|
tok = tok->tokAt(3);
|
|
} else {
|
|
varid = tok->next()->varId();
|
|
tok = tok->next();
|
|
}
|
|
|
|
Variables::VariableUsage *var = variables.find(varid);
|
|
if (var && !var->_allocateMemory) {
|
|
variables.readAll(varid, tok);
|
|
}
|
|
}
|
|
|
|
else if (Token::Match(tok, "return|throw")) {
|
|
for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next()) {
|
|
if (tok2->varId())
|
|
variables.readAll(tok2->varId(), tok);
|
|
else if (tok2->str() == ";")
|
|
break;
|
|
}
|
|
}
|
|
|
|
// assignment
|
|
else if (Token::Match(tok, "*| ++|--| %name% ++|--| %assign%") ||
|
|
Token::Match(tok, "*| ( const| %type% *| ) %name% %assign%")) {
|
|
bool dereference = false;
|
|
bool pre = false;
|
|
bool post = false;
|
|
|
|
if (tok->str() == "*") {
|
|
dereference = true;
|
|
tok = tok->next();
|
|
}
|
|
|
|
if (Token::Match(tok, "( const| %type% *| ) %name% %assign%"))
|
|
tok = tok->link()->next();
|
|
|
|
else if (tok->str() == "(")
|
|
tok = tok->next();
|
|
|
|
if (tok->tokType() == Token::eIncDecOp) {
|
|
pre = true;
|
|
tok = tok->next();
|
|
}
|
|
|
|
if (tok->next()->tokType() == Token::eIncDecOp)
|
|
post = true;
|
|
|
|
const unsigned int varid1 = tok->varId();
|
|
const Token * const start = tok;
|
|
|
|
// assignment in while head..
|
|
bool inwhile = false;
|
|
{
|
|
const Token *parent = tok->astParent();
|
|
while (parent) {
|
|
if (Token::simpleMatch(parent->previous(), "while ("))
|
|
inwhile = true;
|
|
parent = parent->astParent();
|
|
}
|
|
}
|
|
|
|
tok = doAssignment(variables, tok, dereference, scope);
|
|
|
|
if (tok && tok->isAssignmentOp() && tok->str() != "=") {
|
|
variables.use(varid1, tok);
|
|
if (Token::Match(tok, "%assign% %name%")) {
|
|
tok = tok->next();
|
|
variables.read(tok->varId(), tok);
|
|
}
|
|
}
|
|
|
|
if (pre || post)
|
|
variables.use(varid1, tok);
|
|
|
|
if (dereference) {
|
|
Variables::VariableUsage *var = variables.find(varid1);
|
|
if (var && var->_type == Variables::array)
|
|
variables.write(varid1, tok);
|
|
variables.writeAliases(varid1, tok);
|
|
variables.read(varid1, tok);
|
|
} else {
|
|
Variables::VariableUsage *var = variables.find(varid1);
|
|
if (var && (inwhile || start->strAt(-1) == ",")) {
|
|
variables.use(varid1, tok);
|
|
} else if (var && var->_type == Variables::reference) {
|
|
variables.writeAliases(varid1, tok);
|
|
variables.read(varid1, tok);
|
|
}
|
|
// Consider allocating memory separately because allocating/freeing alone does not constitute using the variable
|
|
else if (var && var->_type == Variables::pointer &&
|
|
Token::Match(start, "%name% = new|malloc|calloc|kmalloc|kzalloc|kcalloc|strdup|strndup|vmalloc|g_new0|g_try_new|g_new|g_malloc|g_malloc0|g_try_malloc|g_try_malloc0|g_strdup|g_strndup|g_strdup_printf")) {
|
|
bool allocate = true;
|
|
|
|
if (start->strAt(2) == "new") {
|
|
const Token *type = start->tokAt(3);
|
|
|
|
// skip nothrow
|
|
if (_tokenizer->isCPP() && (Token::simpleMatch(type, "( nothrow )") ||
|
|
Token::simpleMatch(type, "( std :: nothrow )")))
|
|
type = type->link()->next();
|
|
|
|
// is it a user defined type?
|
|
if (!type->isStandardType()) {
|
|
const Variable *variable = start->variable();
|
|
if (!variable || !isRecordTypeWithoutSideEffects(variable->type()))
|
|
allocate = false;
|
|
}
|
|
}
|
|
|
|
if (allocate)
|
|
variables.allocateMemory(varid1, tok);
|
|
else
|
|
variables.write(varid1, tok);
|
|
} else if (varid1 && Token::Match(tok, "%varid% .", varid1)) {
|
|
variables.use(varid1, tok);
|
|
} else {
|
|
variables.write(varid1, tok);
|
|
}
|
|
}
|
|
|
|
Variables::VariableUsage *var2 = variables.find(tok->varId());
|
|
if (var2) {
|
|
if (var2->_type == Variables::reference) {
|
|
variables.writeAliases(tok->varId(), tok);
|
|
variables.read(tok->varId(), tok);
|
|
} else if (tok->varId() != varid1 && Token::Match(tok, "%name% .|["))
|
|
variables.read(tok->varId(), tok);
|
|
else if (tok->varId() != varid1 &&
|
|
var2->_type == Variables::standard &&
|
|
tok->strAt(-1) != "&")
|
|
variables.use(tok->varId(), tok);
|
|
}
|
|
|
|
const Token * const equal = skipBracketsAndMembers(tok->next());
|
|
|
|
// checked for chained assignments
|
|
if (tok != start && equal && equal->str() == "=") {
|
|
const unsigned int varId = tok->varId();
|
|
Variables::VariableUsage *var = variables.find(varId);
|
|
|
|
if (var && var->_type != Variables::reference) {
|
|
variables.read(varId,tok);
|
|
}
|
|
|
|
tok = tok->previous();
|
|
}
|
|
}
|
|
|
|
// assignment
|
|
else if ((Token::Match(tok, "%name% [") && Token::simpleMatch(skipBracketsAndMembers(tok->next()), "=")) ||
|
|
(Token::simpleMatch(tok, "* (") && Token::simpleMatch(tok->next()->link(), ") ="))) {
|
|
const Token *eq = tok;
|
|
while (eq && !eq->isAssignmentOp())
|
|
eq = eq->astParent();
|
|
|
|
const bool deref = eq && eq->astOperand1() && eq->astOperand1()->valueType() && eq->astOperand1()->valueType()->pointer == 0U;
|
|
|
|
if (tok->str() == "*") {
|
|
tok = tok->tokAt(2);
|
|
if (tok->str() == "(")
|
|
tok = tok->link()->next();
|
|
}
|
|
|
|
const unsigned int varid = tok->varId();
|
|
const Variables::VariableUsage *var = variables.find(varid);
|
|
|
|
if (var) {
|
|
// Consider allocating memory separately because allocating/freeing alone does not constitute using the variable
|
|
if (var->_type == Variables::pointer &&
|
|
Token::Match(skipBrackets(tok->next()), "= new|malloc|calloc|kmalloc|kzalloc|kcalloc|strdup|strndup|vmalloc|g_new0|g_try_new|g_new|g_malloc|g_malloc0|g_try_malloc|g_try_malloc0|g_strdup|g_strndup|g_strdup_printf")) {
|
|
variables.allocateMemory(varid, tok);
|
|
} else if (var->_type == Variables::pointer || var->_type == Variables::reference) {
|
|
variables.read(varid, tok);
|
|
variables.writeAliases(varid, tok);
|
|
} else if (var->_type == Variables::pointerArray) {
|
|
tok = doAssignment(variables, tok, deref, scope);
|
|
} else
|
|
variables.writeAll(varid, tok);
|
|
}
|
|
}
|
|
|
|
else if (_tokenizer->isCPP() && Token::Match(tok, "[;{}] %var% <<")) {
|
|
variables.erase(tok->next()->varId());
|
|
}
|
|
|
|
else if (Token::Match(tok, "& %var%")) {
|
|
if (tok->astOperand2()) { // bitop
|
|
variables.read(tok->next()->varId(), tok);
|
|
} else // addressof
|
|
variables.use(tok->next()->varId(), tok); // use = read + write
|
|
} else if (Token::Match(tok, ">>|>>= %name%")) {
|
|
if (_tokenizer->isC() || (tok->previous()->variable() && tok->previous()->variable()->typeEndToken()->isStandardType() && tok->astOperand1() && tok->astOperand1()->str() != ">>"))
|
|
variables.read(tok->next()->varId(), tok);
|
|
else
|
|
variables.use(tok->next()->varId(), tok); // use = read + write
|
|
} else if (Token::Match(tok, "%var% >>|&") && Token::Match(tok->previous(), "[{};:]")) {
|
|
variables.read(tok->varId(), tok);
|
|
}
|
|
|
|
// function parameter
|
|
else if (Token::Match(tok, "[(,] %var% [")) {
|
|
variables.use(tok->next()->varId(), tok); // use = read + write
|
|
} else if (Token::Match(tok, "[(,] %var% [,)]") && tok->previous()->str() != "*") {
|
|
variables.use(tok->next()->varId(), tok); // use = read + write
|
|
} else if (Token::Match(tok, "[(,] (") &&
|
|
Token::Match(tok->next()->link(), ") %var% [,)]")) {
|
|
variables.use(tok->next()->link()->next()->varId(), tok); // use = read + write
|
|
}
|
|
|
|
// function
|
|
else if (Token::Match(tok, "%var% (")) {
|
|
variables.read(tok->varId(), tok);
|
|
}
|
|
|
|
else if (Token::Match(tok->previous(), "[{,] %var% [,}]")) {
|
|
variables.read(tok->varId(), tok);
|
|
}
|
|
|
|
else if (tok->varId() && Token::Match(tok, "%var% .")) {
|
|
variables.use(tok->varId(), tok); // use = read + write
|
|
}
|
|
|
|
else if (tok->isExtendedOp() && tok->next() && tok->next()->varId() && tok->strAt(2) != "=") {
|
|
variables.readAll(tok->next()->varId(), tok);
|
|
}
|
|
|
|
else if (tok->varId() && tok->next() && (tok->next()->str() == ")" || tok->next()->isExtendedOp())) {
|
|
if (Token::Match(tok->tokAt(-2), "%name% ( %var% [,)]") &&
|
|
!(tok->tokAt(-2)->variable() && tok->tokAt(-2)->variable()->isReference()))
|
|
variables.use(tok->varId(), tok);
|
|
else
|
|
variables.readAll(tok->varId(), tok);
|
|
}
|
|
|
|
else if (Token::Match(tok, "%var% ;") && Token::Match(tok->previous(), "[;{}:]")) {
|
|
variables.readAll(tok->varId(), tok);
|
|
}
|
|
|
|
// ++|--
|
|
else if (tok->next() && tok->next()->tokType() == Token::eIncDecOp && tok->next()->astOperand1() && tok->next()->astOperand1()->varId()) {
|
|
if (tok->next()->astParent())
|
|
variables.use(tok->next()->astOperand1()->varId(), tok);
|
|
else
|
|
variables.modified(tok->next()->astOperand1()->varId(), tok);
|
|
}
|
|
|
|
else if (tok->isAssignmentOp()) {
|
|
for (const Token *tok2 = tok->next(); tok2 && tok2->str() != ";"; tok2 = tok2->next()) {
|
|
if (tok2->varId()) {
|
|
if (tok2->strAt(1) == "=")
|
|
variables.write(tok2->varId(), tok);
|
|
else if (tok2->next() && tok2->next()->isAssignmentOp())
|
|
variables.use(tok2->varId(), tok);
|
|
else
|
|
variables.read(tok2->varId(), tok);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckUnusedVar::checkFunctionVariableUsage()
|
|
{
|
|
if (!_settings->isEnabled("style"))
|
|
return;
|
|
|
|
// Parse all executing scopes..
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
// only check functions
|
|
const std::size_t functions = symbolDatabase->functionScopes.size();
|
|
for (std::size_t i = 0; i < functions; ++i) {
|
|
const Scope * scope = symbolDatabase->functionScopes[i];
|
|
|
|
// Bailout when there are lambdas or inline functions
|
|
// TODO: Handle lambdas and inline functions properly
|
|
if (scope->hasInlineOrLambdaFunction())
|
|
continue;
|
|
|
|
// varId, usage {read, write, modified}
|
|
Variables variables;
|
|
|
|
checkFunctionVariableUsage_iterateScopes(scope, variables, false);
|
|
|
|
|
|
// Check usage of all variables in the current scope..
|
|
for (std::map<unsigned int, Variables::VariableUsage>::const_iterator it = variables.varUsage().begin();
|
|
it != variables.varUsage().end();
|
|
++it) {
|
|
const Variables::VariableUsage &usage = it->second;
|
|
|
|
// variable has been marked as unused so ignore it
|
|
if (usage._var->nameToken()->isAttributeUnused() || usage._var->nameToken()->isAttributeUsed())
|
|
continue;
|
|
|
|
// skip things that are only partially implemented to prevent false positives
|
|
if (usage._type == Variables::pointerPointer ||
|
|
usage._type == Variables::pointerArray ||
|
|
usage._type == Variables::referenceArray)
|
|
continue;
|
|
|
|
const std::string &varname = usage._var->name();
|
|
const Variable* var = symbolDatabase->getVariableFromVarId(it->first);
|
|
|
|
// variable has had memory allocated for it, but hasn't done
|
|
// anything with that memory other than, perhaps, freeing it
|
|
if (usage.unused() && !usage._modified && usage._allocateMemory)
|
|
allocatedButUnusedVariableError(usage._lastAccess, varname);
|
|
|
|
// variable has not been written, read, or modified
|
|
else if (usage.unused() && !usage._modified)
|
|
unusedVariableError(usage._var->nameToken(), varname);
|
|
|
|
// variable has not been written but has been modified
|
|
else if (usage._modified && !usage._write && !usage._allocateMemory && var && !var->isStlType())
|
|
unassignedVariableError(usage._var->nameToken(), varname);
|
|
|
|
// variable has been written but not read
|
|
else if (!usage._read && !usage._modified)
|
|
unreadVariableError(usage._lastAccess, varname);
|
|
|
|
// variable has been read but not written
|
|
else if (!usage._write && !usage._allocateMemory && var && !var->isStlType() && !isEmptyType(var->type()))
|
|
unassignedVariableError(usage._var->nameToken(), varname);
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckUnusedVar::unusedVariableError(const Token *tok, const std::string &varname)
|
|
{
|
|
reportError(tok, Severity::style, "unusedVariable", "Unused variable: " + varname, CWE563, false);
|
|
}
|
|
|
|
void CheckUnusedVar::allocatedButUnusedVariableError(const Token *tok, const std::string &varname)
|
|
{
|
|
reportError(tok, Severity::style, "unusedAllocatedMemory", "Variable '" + varname + "' is allocated memory that is never used.");
|
|
}
|
|
|
|
void CheckUnusedVar::unreadVariableError(const Token *tok, const std::string &varname)
|
|
{
|
|
reportError(tok, Severity::style, "unreadVariable", "Variable '" + varname + "' is assigned a value that is never used.");
|
|
}
|
|
|
|
void CheckUnusedVar::unassignedVariableError(const Token *tok, const std::string &varname)
|
|
{
|
|
reportError(tok, Severity::style, "unassignedVariable", "Variable '" + varname + "' is not assigned a value.");
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
// Check that all struct members are used
|
|
//---------------------------------------------------------------------------
|
|
void CheckUnusedVar::checkStructMemberUsage()
|
|
{
|
|
if (!_settings->isEnabled("style"))
|
|
return;
|
|
|
|
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
|
|
|
|
for (std::list<Scope>::const_iterator scope = symbolDatabase->scopeList.cbegin(); scope != symbolDatabase->scopeList.cend(); ++scope) {
|
|
if (scope->type != Scope::eStruct && scope->type != Scope::eUnion)
|
|
continue;
|
|
|
|
if (scope->classStart->fileIndex() != 0 || scope->className.empty())
|
|
continue;
|
|
|
|
// Bail out if struct/union contains any functions
|
|
if (!scope->functionList.empty())
|
|
continue;
|
|
|
|
// bail out if struct is inherited
|
|
bool bailout = false;
|
|
for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.cbegin(); i != symbolDatabase->scopeList.cend(); ++i) {
|
|
if (i->definedType) {
|
|
for (size_t j = 0; j < i->definedType->derivedFrom.size(); j++) {
|
|
if (i->definedType->derivedFrom[j].type == scope->definedType) {
|
|
bailout = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (bailout)
|
|
continue;
|
|
|
|
// bail out for extern/global struct
|
|
for (size_t i = 0; i < symbolDatabase->getVariableListSize(); i++) {
|
|
const Variable* var = symbolDatabase->getVariableFromVarId(i);
|
|
if (var && (var->isExtern() || (var->isGlobal() && !var->isStatic())) && var->typeEndToken()->str() == scope->className) {
|
|
bailout = true;
|
|
break;
|
|
}
|
|
}
|
|
if (bailout)
|
|
continue;
|
|
|
|
// Bail out if some data is casted to struct..
|
|
const std::string castPattern("( struct| " + scope->className + " * ) & %name% [");
|
|
if (Token::findmatch(scope->classEnd, castPattern.c_str()))
|
|
continue;
|
|
|
|
// Try to prevent false positives when struct members are not used directly.
|
|
if (Token::findmatch(scope->classEnd, (scope->className + " %type%| *").c_str()))
|
|
continue;
|
|
|
|
for (std::list<Variable>::const_iterator var = scope->varlist.cbegin(); var != scope->varlist.cend(); ++var) {
|
|
// declaring a POD member variable?
|
|
if (!var->typeStartToken()->isStandardType() && !var->isPointer())
|
|
continue;
|
|
|
|
// Check if the struct member variable is used anywhere in the file
|
|
if (Token::findsimplematch(_tokenizer->tokens(), (". " + var->name()).c_str()))
|
|
continue;
|
|
|
|
unusedStructMemberError(var->nameToken(), scope->className, var->name(), scope->type == Scope::eUnion);
|
|
}
|
|
}
|
|
}
|
|
|
|
void CheckUnusedVar::unusedStructMemberError(const Token *tok, const std::string &structname, const std::string &varname, bool isUnion)
|
|
{
|
|
const char* prefix = isUnion ? "union member '" : "struct member '";
|
|
reportError(tok, Severity::style, "unusedStructMember", std::string(prefix) + structname + "::" + varname + "' is never used.");
|
|
}
|
|
|
|
bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)
|
|
{
|
|
// a type that has no side effects (no constructors and no members with constructors)
|
|
/** @todo false negative: check constructors for side effects */
|
|
|
|
const std::pair<std::map<const Type *,bool>::iterator,bool> found=isRecordTypeWithoutSideEffectsMap.insert(
|
|
std::pair<const Type *,bool>(type,false)); //Initialize with side effects for possible recursions
|
|
bool & withoutSideEffects=found.first->second;
|
|
if (!found.second)
|
|
return withoutSideEffects;
|
|
|
|
if (type && type->classScope && type->classScope->numConstructors == 0 &&
|
|
(type->classScope->varlist.empty() || type->needInitialization == Type::True)) {
|
|
for (std::vector<Type::BaseInfo>::const_iterator i = type->derivedFrom.begin(); i != type->derivedFrom.end(); ++i) {
|
|
if (!isRecordTypeWithoutSideEffects(i->type)) {
|
|
withoutSideEffects=false;
|
|
return withoutSideEffects;
|
|
}
|
|
}
|
|
withoutSideEffects=true;
|
|
return withoutSideEffects;
|
|
}
|
|
|
|
withoutSideEffects=false; // unknown types are assumed to have side effects
|
|
return withoutSideEffects;
|
|
}
|
|
|
|
bool CheckUnusedVar::isEmptyType(const Type* type)
|
|
{
|
|
// a type that has no variables and no constructor
|
|
|
|
const std::pair<std::map<const Type *,bool>::iterator,bool> found=isEmptyTypeMap.insert(
|
|
std::pair<const Type *,bool>(type,false));
|
|
bool & emptyType=found.first->second;
|
|
if (!found.second)
|
|
return emptyType;
|
|
|
|
if (type && type->classScope && type->classScope->numConstructors == 0 &&
|
|
(type->classScope->varlist.empty())) {
|
|
for (std::vector<Type::BaseInfo>::const_iterator i = type->derivedFrom.begin(); i != type->derivedFrom.end(); ++i) {
|
|
if (!isEmptyType(i->type)) {
|
|
emptyType=false;
|
|
return emptyType;
|
|
}
|
|
}
|
|
emptyType=true;
|
|
return emptyType;
|
|
}
|
|
|
|
emptyType=false; // unknown types are assumed to be nonempty
|
|
return emptyType;
|
|
}
|