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Evaluate container sizes in forward analysis (#3338)

This commit is contained in:
Paul Fultz II 2021-07-16 11:49:07 -05:00 committed by GitHub
parent f5fac96670
commit 942202aede
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7 changed files with 138 additions and 29 deletions
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9
lib/analyzer.h
View File

@ -128,15 +128,22 @@ struct Analyzer {
None = 0,
Quiet = (1 << 0),
Absolute = (1 << 1),
ContainerEmpty = (1 << 2),
};
};
enum class Evaluate { Integral, ContainerEmpty };
/// Analyze a token
virtual Action analyze(const Token* tok, Direction d) const = 0;
/// Update the state of the value
virtual void update(Token* tok, Action a, Direction d) = 0;
/// Try to evaluate the value of a token(most likely a condition)
virtual std::vector<int> evaluate(const Token* tok, const Token* ctx = nullptr) const = 0;
virtual std::vector<int> evaluate(Evaluate e, const Token* tok, const Token* ctx = nullptr) const = 0;
std::vector<int> evaluate(const Token* tok, const Token* ctx = nullptr) const
{
return evaluate(Evaluate::Integral, tok, ctx);
}
/// Lower any values to possible
virtual bool lowerToPossible() = 0;
/// Lower any values to inconclusive

8
lib/forwardanalyzer.cpp
View File

@ -565,7 +565,13 @@ struct ForwardTraversal {
Token* conTok = condTok->astOperand2();
if (conTok && updateRecursive(conTok) == Progress::Break)
return Break();
if (updateLoop(end, endBlock, condTok) == Progress::Break)
bool isEmpty = false;
std::vector<int> result = analyzer->evaluate(Analyzer::Evaluate::ContainerEmpty, conTok);
if (result.empty())
analyzer->assume(conTok, false, Analyzer::Assume::ContainerEmpty);
else
isEmpty = result.front() != 0;
if (!isEmpty && updateLoop(end, endBlock, condTok) == Progress::Break)
return Break();
} else {
Token* stepTok = getStepTok(tok);

52
lib/programmemory.cpp
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@ -74,6 +74,15 @@ bool ProgramMemory::getContainerEmptyValue(nonneg int exprid, MathLib::bigint* r
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;
@ -142,6 +151,36 @@ bool conditionIsTrue(const Token *condition, const ProgramMemory &programMemory)
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, "==|>=|<=|<|>|!=")) {
@ -169,7 +208,12 @@ void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Toke
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, "&&")) {
@ -184,6 +228,9 @@ void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Toke
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);
}
}
@ -331,9 +378,12 @@ void ProgramMemoryState::addState(const Token* tok, const ProgramMemory::Map& va
replace(pm, tok);
}
void ProgramMemoryState::assume(const Token* tok, bool b)
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();

3
lib/programmemory.h
View File

@ -21,6 +21,7 @@ struct ProgramMemory {
bool getContainerSizeValue(nonneg int exprid, MathLib::bigint* result) const;
bool getContainerEmptyValue(nonneg int exprid, MathLib::bigint* result) const;
void setContainerSizeValue(nonneg int exprid, MathLib::bigint value, bool isEqual = true);
void setUnknown(nonneg int exprid);
@ -49,7 +50,7 @@ struct ProgramMemoryState {
void addState(const Token* tok, const ProgramMemory::Map& vars);
void assume(const Token* tok, bool b);
void assume(const Token* tok, bool b, bool isEmpty = false);
void removeModifiedVars(const Token* tok);

2
lib/symboldatabase.cpp
View File

@ -1455,7 +1455,7 @@ void SymbolDatabase::createSymbolDatabaseExprIds()
continue;
if (tok1->exprId() == tok2->exprId())
continue;
if (!isSameExpression(isCPP(), true, tok1, tok2, mSettings->library, true, false))
if (!isSameExpression(isCPP(), true, tok1, tok2, mSettings->library, false, false))
continue;
nonneg int cid = std::min(tok1->exprId(), tok2->exprId());
tok1->exprId(cid);

27
lib/valueflow.cpp
View File

@ -2000,7 +2000,7 @@ struct ValueFlowAnalyzer : Analyzer {
// Check if its assigned to the same value
if (value && !value->isImpossible() && Token::simpleMatch(tok->astParent(), "=") && astIsLHS(tok) &&
astIsIntegral(tok->astParent()->astOperand2(), false)) {
std::vector<int> result = evaluate(tok->astParent()->astOperand2());
std::vector<int> result = evaluate(Evaluate::Integral, tok->astParent()->astOperand2());
if (!result.empty() && value->equalTo(result.front()))
return Action::Idempotent;
}
@ -2177,7 +2177,9 @@ struct ValueFlowAnalyzer : Analyzer {
return Action::None;
}
virtual std::vector<int> evaluate(const Token* tok, const Token* ctx = nullptr) const OVERRIDE {
virtual std::vector<int> evaluate(Evaluate e, const Token* tok, const Token* ctx = nullptr) const OVERRIDE
{
if (e == Evaluate::Integral) {
if (tok->hasKnownIntValue())
return {static_cast<int>(tok->values().front().intvalue)};
std::vector<int> result;
@ -2196,13 +2198,27 @@ struct ValueFlowAnalyzer : Analyzer {
}
return result;
} else if (e == Evaluate::ContainerEmpty) {
const ValueFlow::Value* value = ValueFlow::findValue(tok->values(), nullptr, [](const ValueFlow::Value& v) {
return v.isKnown() && v.isContainerSizeValue();
});
if (value)
return {value->intvalue == 0};
ProgramMemory pm = pms.get(tok, ctx, getProgramState());
MathLib::bigint out = 0;
if (pm.getContainerEmptyValue(tok->exprId(), &out))
return {static_cast<int>(out)};
return {};
} else {
return {};
}
}
virtual void assume(const Token* tok, bool state, unsigned int flags) OVERRIDE {
// Update program state
pms.removeModifiedVars(tok);
pms.addState(tok, getProgramState());
pms.assume(tok, state);
pms.assume(tok, state, flags & Assume::ContainerEmpty);
bool isCondBlock = false;
const Token* parent = tok->astParent();
@ -2221,9 +2237,14 @@ struct ValueFlowAnalyzer : Analyzer {
}
if (!(flags & Assume::Quiet)) {
if (flags & Assume::ContainerEmpty) {
std::string s = state ? "empty" : "not empty";
addErrorPath(tok, "Assuming container is " + s);
} else {
std::string s = state ? "true" : "false";
addErrorPath(tok, "Assuming condition is " + s);
}
}
if (!(flags & Assume::Absolute))
makeConditional();
}

24
test/teststl.cpp
View File

@ -538,6 +538,30 @@ private:
" return Name;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
checkNormal("bool f(bool b) {\n"
" std::vector<int> v;\n"
" if (b)\n"
" v.push_back(0);\n"
" for(auto i:v)\n"
" if (v[i] > 0)\n"
" return true;\n"
" return false;\n"
"}\n");
ASSERT_EQUALS("test.cpp:6:style:Consider using std::any_of algorithm instead of a raw loop.\n", errout.str());
checkNormal("std::vector<int> range(int n);\n"
"bool f(bool b) {\n"
" std::vector<int> v;\n"
" if (b)\n"
" v.push_back(1);\n"
" assert(range(v.size()).size() == v.size());\n"
" for(auto i:range(v.size()))\n"
" if (v[i] > 0)\n"
" return true;\n"
" return false;\n"
"}\n");
ASSERT_EQUALS("test.cpp:8:style:Consider using std::any_of algorithm instead of a raw loop.\n", errout.str());
}
void outOfBoundsIndexExpression() {