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cppcheck/lib/programmemory.cpp

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#include "programmemory.h"
#include "astutils.h"
#include "mathlib.h"
#include "symboldatabase.h"
#include "token.h"
#include "valueflow.h"
#include <algorithm>
#include <cassert>
#include <functional>
#include <limits>
#include <memory>
void ProgramMemory::setValue(nonneg int exprid, const ValueFlow::Value& value)
{
values[exprid] = value;
}
const ValueFlow::Value* ProgramMemory::getValue(nonneg int exprid, bool impossible) const
{
const ProgramMemory::Map::const_iterator it = values.find(exprid);
const bool found = it != values.end() && (impossible || !it->second.isImpossible());
if (found)
return &it->second;
else
return nullptr;
}
bool ProgramMemory::getIntValue(nonneg int exprid, MathLib::bigint* result) const
{
const ValueFlow::Value* value = getValue(exprid);
if (value && value->isIntValue()) {
*result = value->intvalue;
return true;
}
return false;
}
void ProgramMemory::setIntValue(nonneg int exprid, MathLib::bigint value)
{
values[exprid] = ValueFlow::Value(value);
}
bool ProgramMemory::getTokValue(nonneg int exprid, const Token** result) const
{
const ValueFlow::Value* value = getValue(exprid);
if (value && value->isTokValue()) {
*result = value->tokvalue;
return true;
}
return false;
}
bool ProgramMemory::getContainerSizeValue(nonneg int exprid, MathLib::bigint* result) const
{
const ValueFlow::Value* value = getValue(exprid);
if (value && value->isContainerSizeValue()) {
*result = value->intvalue;
return true;
}
return false;
}
bool ProgramMemory::getContainerEmptyValue(nonneg int exprid, MathLib::bigint* result) const
{
const ValueFlow::Value* value = getValue(exprid, true);
if (value && value->isContainerSizeValue()) {
if (value->isImpossible() && value->intvalue == 0) {
*result = false;
return true;
}
if (!value->isImpossible()) {
*result = (value->intvalue == 0);
return true;
}
}
return false;
}
void ProgramMemory::setContainerSizeValue(nonneg int exprid, MathLib::bigint value, bool isEqual)
{
ValueFlow::Value v(value);
v.valueType = ValueFlow::Value::ValueType::CONTAINER_SIZE;
if (!isEqual)
v.valueKind = ValueFlow::Value::ValueKind::Impossible;
values[exprid] = v;
}
void ProgramMemory::setUnknown(nonneg int exprid)
{
values[exprid].valueType = ValueFlow::Value::ValueType::UNINIT;
}
bool ProgramMemory::hasValue(nonneg int exprid)
{
return values.find(exprid) != values.end();
}
void ProgramMemory::swap(ProgramMemory &pm)
{
values.swap(pm.values);
}
void ProgramMemory::clear()
{
values.clear();
}
bool ProgramMemory::empty() const
{
return values.empty();
}
void ProgramMemory::replace(const ProgramMemory &pm)
{
for (auto&& p : pm.values) {
values[p.first] = p.second;
}
}
void ProgramMemory::insert(const ProgramMemory &pm)
{
for (auto&& p:pm.values)
values.insert(p);
}
bool conditionIsFalse(const Token *condition, const ProgramMemory &programMemory)
{
if (!condition)
return false;
if (condition->str() == "&&") {
return conditionIsFalse(condition->astOperand1(), programMemory) ||
conditionIsFalse(condition->astOperand2(), programMemory);
}
ProgramMemory progmem(programMemory);
MathLib::bigint result = 0;
bool error = false;
execute(condition, &progmem, &result, &error);
return !error && result == 0;
}
bool conditionIsTrue(const Token *condition, const ProgramMemory &programMemory)
{
if (!condition)
return false;
if (condition->str() == "||") {
return conditionIsTrue(condition->astOperand1(), programMemory) ||
conditionIsTrue(condition->astOperand2(), programMemory);
}
ProgramMemory progmem(programMemory);
bool error = false;
MathLib::bigint result = 0;
execute(condition, &progmem, &result, &error);
return !error && result == 1;
}
static const Token* getContainerFromEmpty(const Token* tok)
{
if (!Token::Match(tok->tokAt(-2), ". %name% ("))
return nullptr;
const Token* containerTok = tok->tokAt(-2)->astOperand1();
if (!astIsContainer(containerTok))
return nullptr;
if (containerTok->valueType()->container &&
containerTok->valueType()->container->getYield(tok->strAt(-1)) == Library::Container::Yield::EMPTY)
return containerTok;
if (Token::simpleMatch(tok->tokAt(-1), "empty ( )"))
return containerTok;
return nullptr;
}
static const Token* getContainerFromSize(const Token* tok)
{
if (!Token::Match(tok->tokAt(-2), ". %name% ("))
return nullptr;
const Token* containerTok = tok->tokAt(-2)->astOperand1();
if (!astIsContainer(containerTok))
return nullptr;
if (containerTok->valueType()->container &&
containerTok->valueType()->container->getYield(tok->strAt(-1)) == Library::Container::Yield::SIZE)
return containerTok;
if (Token::Match(tok->tokAt(-1), "size|length ( )"))
return containerTok;
return nullptr;
}
void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Token* endTok, const Settings* settings, bool then)
{
if (Token::Match(tok, "==|>=|<=|<|>|!=")) {
if (then && !Token::Match(tok, "==|>=|<=|<|>"))
return;
if (!then && !Token::Match(tok, "<|>|!="))
return;
ValueFlow::Value truevalue;
ValueFlow::Value falsevalue;
const Token* vartok = parseCompareInt(tok, truevalue, falsevalue, [&](const Token* t) -> std::vector<MathLib::bigint> {
if (t->hasKnownIntValue())
return {t->values().front().intvalue};
MathLib::bigint result = 0;
bool error = false;
execute(t, &pm, &result, &error);
if (!error)
return {result};
return std::vector<MathLib::bigint>{};
});
if (!vartok)
return;
if (vartok->exprId() == 0)
return;
if (!truevalue.isIntValue())
return;
if (endTok && isExpressionChanged(vartok, tok->next(), endTok, settings, true))
return;
bool impossible = (tok->str() == "==" && !then) || (tok->str() == "!=" && then);
if (!impossible)
pm.setIntValue(vartok->exprId(), then ? truevalue.intvalue : falsevalue.intvalue);
const Token* containerTok = getContainerFromSize(vartok);
if (containerTok)
pm.setContainerSizeValue(containerTok->exprId(), then ? truevalue.intvalue : falsevalue.intvalue, !impossible);
} else if (Token::simpleMatch(tok, "!")) {
programMemoryParseCondition(pm, tok->astOperand1(), endTok, settings, !then);
} else if (then && Token::simpleMatch(tok, "&&")) {
programMemoryParseCondition(pm, tok->astOperand1(), endTok, settings, then);
programMemoryParseCondition(pm, tok->astOperand2(), endTok, settings, then);
} else if (!then && Token::simpleMatch(tok, "||")) {
programMemoryParseCondition(pm, tok->astOperand1(), endTok, settings, then);
programMemoryParseCondition(pm, tok->astOperand2(), endTok, settings, then);
} else if (tok->exprId() > 0) {
if (then && !astIsPointer(tok) && !astIsBool(tok))
return;
if (endTok && isExpressionChanged(tok, tok->next(), endTok, settings, true))
return;
pm.setIntValue(tok->exprId(), then);
const Token* containerTok = getContainerFromEmpty(tok);
if (containerTok)
pm.setContainerSizeValue(containerTok->exprId(), 0, then);
}
}
static void fillProgramMemoryFromConditions(ProgramMemory& pm, const Scope* scope, const Token* endTok, const Settings* settings)
{
if (!scope)
return;
if (!scope->isLocal())
return;
assert(scope != scope->nestedIn);
fillProgramMemoryFromConditions(pm, scope->nestedIn, endTok, settings);
if (scope->type == Scope::eIf || scope->type == Scope::eWhile || scope->type == Scope::eElse || scope->type == Scope::eFor) {
const Token* condTok = getCondTokFromEnd(scope->bodyEnd);
if (!condTok)
return;
MathLib::bigint result = 0;
bool error = false;
execute(condTok, &pm, &result, &error);
if (error)
programMemoryParseCondition(pm, condTok, endTok, settings, scope->type != Scope::eElse);
}
}
static void fillProgramMemoryFromConditions(ProgramMemory& pm, const Token* tok, const Settings* settings)
{
fillProgramMemoryFromConditions(pm, tok->scope(), tok, settings);
}
static void fillProgramMemoryFromAssignments(ProgramMemory& pm, const Token* tok, const ProgramMemory& state, const ProgramMemory::Map& vars)
{
int indentlevel = 0;
for (const Token *tok2 = tok; tok2; tok2 = tok2->previous()) {
if ((Token::simpleMatch(tok2, "=") || Token::Match(tok2->previous(), "%var% (|{")) && tok2->astOperand1() &&
tok2->astOperand2()) {
bool setvar = false;
const Token* vartok = tok2->astOperand1();
const Token* valuetok = tok2->astOperand2();
for (const auto& p:vars) {
if (p.first != vartok->exprId())
continue;
if (vartok == tok)
continue;
pm.setValue(vartok->exprId(), p.second);
setvar = true;
}
if (!setvar) {
if (!pm.hasValue(vartok->exprId())) {
MathLib::bigint result = 0;
bool error = false;
execute(valuetok, &pm, &result, &error);
if (!error)
pm.setIntValue(vartok->exprId(), result);
else
pm.setUnknown(vartok->exprId());
}
}
} else if (tok2->exprId() > 0 && Token::Match(tok2, ".|(|[|*|%var%") && !pm.hasValue(tok2->exprId()) &&
isVariableChanged(tok2, 0, nullptr, true)) {
pm.setUnknown(tok2->exprId());
}
if (tok2->str() == "{") {
if (indentlevel <= 0)
break;
--indentlevel;
if (Token::simpleMatch(tok2->previous(), "else {"))
tok2 = tok2->linkAt(-2)->previous();
}
if (tok2->str() == "}") {
const Token *cond = getCondTokFromEnd(tok2);
const bool inElse = Token::simpleMatch(tok2->link()->previous(), "else {");
if (cond) {
if (conditionIsFalse(cond, state)) {
if (inElse) {
++indentlevel;
continue;
}
tok2 = cond->astParent()->previous();
} else if (conditionIsTrue(cond, state)) {
if (inElse)
tok2 = tok2->link()->tokAt(-2);
++indentlevel;
continue;
}
}
break;
}
}
}
static void removeModifiedVars(ProgramMemory& pm, const Token* tok, const Token* origin)
{
for (auto i = pm.values.begin(), last = pm.values.end(); i != last;) {
if (isVariableChanged(origin, tok, i->first, false, nullptr, true)) {
i = pm.values.erase(i);
} else {
++i;
}
}
}
static ProgramMemory getInitialProgramState(const Token* tok,
const Token* origin,
const ProgramMemory::Map& vars = ProgramMemory::Map {})
{
ProgramMemory pm;
if (origin) {
fillProgramMemoryFromConditions(pm, origin, nullptr);
const ProgramMemory state = pm;
fillProgramMemoryFromAssignments(pm, tok, state, vars);
removeModifiedVars(pm, tok, origin);
}
return pm;
}
void ProgramMemoryState::insert(const ProgramMemory &pm, const Token* origin)
{
if (origin)
for (auto&& p:pm.values)
origins.insert(std::make_pair(p.first, origin));
state.insert(pm);
}
void ProgramMemoryState::replace(const ProgramMemory &pm, const Token* origin)
{
if (origin)
for (auto&& p:pm.values)
origins[p.first] = origin;
state.replace(pm);
}
void ProgramMemoryState::addState(const Token* tok, const ProgramMemory::Map& vars)
{
ProgramMemory pm = state;
fillProgramMemoryFromConditions(pm, tok, nullptr);
for (const auto& p:vars) {
nonneg int exprid = p.first;
const ValueFlow::Value &value = p.second;
pm.setValue(exprid, value);
if (value.varId)
pm.setIntValue(value.varId, value.varvalue);
}
ProgramMemory local = pm;
fillProgramMemoryFromAssignments(pm, tok, local, vars);
replace(pm, tok);
}
void ProgramMemoryState::assume(const Token* tok, bool b, bool isEmpty)
{
ProgramMemory pm = state;
if (isEmpty)
pm.setContainerSizeValue(tok->exprId(), 0, b);
else
programMemoryParseCondition(pm, tok, nullptr, nullptr, b);
const Token* origin = tok;
const Token* top = tok->astTop();
if (top && Token::Match(top->previous(), "for|while ("))
origin = top->link();
replace(pm, origin);
}
void ProgramMemoryState::removeModifiedVars(const Token* tok)
{
for (auto i = state.values.begin(), last = state.values.end(); i != last;) {
if (isVariableChanged(origins[i->first], tok, i->first, false, nullptr, true)) {
origins.erase(i->first);
i = state.values.erase(i);
} else {
++i;
}
}
}
ProgramMemory ProgramMemoryState::get(const Token* tok, const Token* ctx, const ProgramMemory::Map& vars) const
{
ProgramMemoryState local = *this;
if (ctx)
local.addState(ctx, vars);
const Token* start = previousBeforeAstLeftmostLeaf(tok);
if (!start)
start = tok;
if (!ctx || precedes(start, ctx)) {
local.removeModifiedVars(start);
local.addState(start, vars);
} else {
local.removeModifiedVars(ctx);
}
return local.state;
}
ProgramMemory getProgramMemory(const Token *tok, const ProgramMemory::Map& vars)
{
ProgramMemory programMemory;
for (const auto& p:vars) {
const ValueFlow::Value &value = p.second;
programMemory.replace(getInitialProgramState(tok, value.tokvalue));
programMemory.replace(getInitialProgramState(tok, value.condition));
}
fillProgramMemoryFromConditions(programMemory, tok, nullptr);
ProgramMemory state;
for (const auto& p:vars) {
nonneg int exprid = p.first;
const ValueFlow::Value &value = p.second;
programMemory.setValue(exprid, value);
if (value.varId)
programMemory.setIntValue(value.varId, value.varvalue);
}
state = programMemory;
fillProgramMemoryFromAssignments(programMemory, tok, state, vars);
return programMemory;
}
ProgramMemory getProgramMemory(const Token* tok, nonneg int exprid, const ValueFlow::Value& value)
{
ProgramMemory programMemory;
programMemory.replace(getInitialProgramState(tok, value.tokvalue));
programMemory.replace(getInitialProgramState(tok, value.condition));
fillProgramMemoryFromConditions(programMemory, tok, nullptr);
programMemory.setValue(exprid, value);
if (value.varId)
programMemory.setIntValue(value.varId, value.varvalue);
const ProgramMemory state = programMemory;
fillProgramMemoryFromAssignments(programMemory, tok, state, {{exprid, value}});
return programMemory;
}
static PMEvaluateFunction evaluateAsInt(PMEvaluateFunction f, ValueFlow::Value::ValueType t)
{
return [=](const Token* expr, ProgramMemory* const programMemory, MathLib::bigint* result) -> bool {
const ValueFlow::Value* value = expr->getKnownValue(t);
if (!value)
value = programMemory->getValue(expr->exprId());
if (value && value->valueType == t)
{
*result = value->intvalue;
return true;
}
return f && f(expr, programMemory, result);
};
}
static std::set<ValueFlow::Value::ValueType> findIteratorTypes(const ProgramMemory& pm)
{
std::set<ValueFlow::Value::ValueType> result;
for (auto&& p : pm.values) {
if (p.second.isIteratorValue())
result.insert(p.second.valueType);
if (result.size() == 2)
break;
}
return result;
}
static bool isIterator(const Token* expr)
{
if (!expr)
return false;
if (astIsIterator(expr))
return true;
return std::any_of(expr->values().begin(), expr->values().end(), std::mem_fn(&ValueFlow::Value::isIteratorValue));
}
void execute(const Token* expr,
ProgramMemory* const programMemory,
MathLib::bigint* result,
bool* error,
const PMEvaluateFunction& f)
{
if (!expr)
*error = true;
else if (f && f(expr, programMemory, result))
*error = false;
else if (expr->hasKnownIntValue() && !expr->isAssignmentOp()) {
*result = expr->values().front().intvalue;
}
else if (expr->isNumber()) {
*result = MathLib::toLongNumber(expr->str());
if (MathLib::isFloat(expr->str()))
*error = true;
}
else if (expr->varId() > 0) {
if (!programMemory->getIntValue(expr->varId(), result))
*error = true;
}
else if (Token::Match(expr->tokAt(-3), "%var% . %name% (") && astIsContainer(expr->tokAt(-3))) {
const Token* containerTok = expr->tokAt(-3);
Library::Container::Yield yield = containerTok->valueType()->container->getYield(expr->strAt(-1));
if (yield == Library::Container::Yield::SIZE) {
if (!programMemory->getContainerSizeValue(containerTok->exprId(), result))
*error = true;
} else if (yield == Library::Container::Yield::EMPTY) {
if (!programMemory->getContainerEmptyValue(containerTok->exprId(), result))
*error = true;
} else {
*error = true;
}
}
else if (expr->exprId() > 0 && programMemory->hasValue(expr->exprId())) {
if (!programMemory->getIntValue(expr->exprId(), result))
*error = true;
}
else if (expr->isComparisonOp()) {
MathLib::bigint result1(0), result2(0);
bool error1 = false;
bool error2 = false;
execute(expr->astOperand1(), programMemory, &result1, &error1, f);
execute(expr->astOperand2(), programMemory, &result2, &error2, f);
if (error1 && error2 && (isIterator(expr->astOperand1()) || isIterator(expr->astOperand2()))) {
for (ValueFlow::Value::ValueType t : findIteratorTypes(*programMemory)) {
execute(expr->astOperand1(), programMemory, &result1, &error1, evaluateAsInt(f, t));
execute(expr->astOperand2(), programMemory, &result2, &error2, evaluateAsInt(f, t));
if (!error1 && !error2)
break;
}
}
if (error1 && error2) {
*error = true;
} else if (error1 && !error2) {
ValueFlow::Value v = inferCondition(expr->str(), expr->astOperand1(), result2);
*error = !v.isKnown();
*result = v.intvalue;
} else if (!error1 && error2) {
ValueFlow::Value v = inferCondition(expr->str(), result1, expr->astOperand2());
*error = !v.isKnown();
*result = v.intvalue;
} else {
if (expr->str() == "<")
*result = result1 < result2;
else if (expr->str() == "<=")
*result = result1 <= result2;
else if (expr->str() == ">")
*result = result1 > result2;
else if (expr->str() == ">=")
*result = result1 >= result2;
else if (expr->str() == "==")
*result = result1 == result2;
else if (expr->str() == "!=")
*result = result1 != result2;
}
}
else if (expr->isAssignmentOp()) {
execute(expr->astOperand2(), programMemory, result, error, f);
if (!expr->astOperand1() || !expr->astOperand1()->exprId())
*error = true;
if (*error)
return;
if (expr->str() == "=") {
programMemory->setIntValue(expr->astOperand1()->exprId(), *result);
return;
}
long long intValue;
if (!programMemory->getIntValue(expr->astOperand1()->exprId(), &intValue)) {
*error = true;
return;
}
if (expr->str() == "+=")
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue + *result);
else if (expr->str() == "-=")
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue - *result);
else if (expr->str() == "*=")
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue * *result);
else if (expr->str() == "/=" && *result != 0)
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue / *result);
else if (expr->str() == "%=" && *result != 0)
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue % *result);
else if (expr->str() == "&=")
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue & *result);
else if (expr->str() == "|=")
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue | *result);
else if (expr->str() == "^=")
programMemory->setIntValue(expr->astOperand1()->exprId(), intValue ^ *result);
}
else if (Token::Match(expr, "++|--")) {
if (!expr->astOperand1() || expr->astOperand1()->exprId() == 0)
*error = true;
else {
long long intValue;
if (!programMemory->getIntValue(expr->astOperand1()->exprId(), &intValue))
*error = true;
else {
if (intValue == 0 &&
expr->str() == "--" &&
expr->astOperand1()->variable() &&
expr->astOperand1()->variable()->isUnsigned())
*error = true; // overflow
*result = intValue + (expr->str() == "++" ? 1 : -1);
programMemory->setIntValue(expr->astOperand1()->exprId(), *result);
}
}
}
else if (expr->isArithmeticalOp() && expr->astOperand1() && expr->astOperand2()) {
MathLib::bigint result1(0), result2(0);
execute(expr->astOperand1(), programMemory, &result1, error, f);
execute(expr->astOperand2(), programMemory, &result2, error, f);
if (expr->str() == "+")
*result = result1 + result2;
else if (expr->str() == "-")
*result = result1 - result2;
else if (expr->str() == "*") {
if (result2 && (result1 > std::numeric_limits<MathLib::bigint>::max()/result2))
*error = true;
else
*result = result1 * result2;
} else if (result2 == 0)
*error = true;
else if (expr->str() == "/")
*result = result1 / result2;
else if (expr->str() == "%")
*result = result1 % result2;
else if (expr->str() == "<<") {
if (result2 < 0 || result1 < 0 || result2 >= MathLib::bigint_bits) { // don't perform UB
*error= true;
} else {
*result = result1 << result2;
}
} else if (expr->str() == ">>") {
if (result2 < 0 || result2 >= MathLib::bigint_bits) { // don't perform UB
*error=true;
} else {
*result = result1 >> result2;
}
}
}
else if (expr->str() == "&&") {
bool error1 = false;
execute(expr->astOperand1(), programMemory, result, &error1, f);
if (!error1 && *result == 0)
*result = 0;
else {
bool error2 = false;
execute(expr->astOperand2(), programMemory, result, &error2, f);
if (error1 || error2)
*error = true;
}
}
else if (expr->str() == "||") {
execute(expr->astOperand1(), programMemory, result, error, f);
if (*result == 1 && *error == false)
*result = 1;
else if (*result == 0 && *error == false)
execute(expr->astOperand2(), programMemory, result, error, f);
}
else if (expr->str() == "!") {
execute(expr->astOperand1(), programMemory, result, error, f);
*result = !(*result);
}
else if (expr->str() == "," && expr->astOperand1() && expr->astOperand2()) {
execute(expr->astOperand1(), programMemory, result, error, f);
execute(expr->astOperand2(), programMemory, result, error, f);
}
else if (expr->str() == "[" && expr->astOperand1() && expr->astOperand2()) {
const Token *tokvalue = nullptr;
if (!programMemory->getTokValue(expr->astOperand1()->exprId(), &tokvalue)) {
auto tokvalue_it = std::find_if(expr->astOperand1()->values().begin(),
expr->astOperand1()->values().end(),
std::mem_fn(&ValueFlow::Value::isTokValue));
if (tokvalue_it == expr->astOperand1()->values().end()) {
*error = true;
return;
}
tokvalue = tokvalue_it->tokvalue;
}
if (!tokvalue || !tokvalue->isLiteral()) {
*error = true;
return;
}
const std::string strValue = tokvalue->strValue();
MathLib::bigint index = 0;
execute(expr->astOperand2(), programMemory, &index, error, f);
if (index >= 0 && index < strValue.size())
*result = strValue[index];
else if (index == strValue.size())
*result = 0;
else
*error = true;
}
else if (expr->str() == "(" && expr->isCast()) {
if (Token::simpleMatch(expr->previous(), ">") && expr->previous()->link())
execute(expr->astOperand2(), programMemory, result, error);
else
execute(expr->astOperand1(), programMemory, result, error);
} else
*error = true;
}
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