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ValueFlow: better FwdAnalysis for complex expressions

This commit is contained in:
Daniel Marjamäki 2019-01-01 18:23:47 +01:00
parent be7afac875
commit 115be7dfc8
4 changed files with 38 additions and 13 deletions
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19
lib/astutils.cpp
View File

@ -1121,6 +1121,10 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
}
if (tok->str() == "}") {
// Known value => possible value
if (tok->scope() == expr->scope())
mValueFlowKnown = false;
Scope::ScopeType scopeType = tok->scope()->type;
if (scopeType == Scope::eWhile || scopeType == Scope::eFor || scopeType == Scope::eDo) {
// check condition
@ -1173,8 +1177,12 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
parent = parent->astParent();
if (parent && isSameExpression(mCpp, false, expr, parent, mLibrary, false, false, nullptr)) {
same = true;
if (mWhat == What::ValueFlow)
mValueFlow.push_back(parent);
if (mWhat == What::ValueFlow) {
KnownAndToken v;
v.known = mValueFlowKnown;
v.token = parent;
mValueFlow.push_back(v);
}
}
if (!same && Token::Match(parent, ". %var%") && parent->next()->varId() && exprVarIds.find(parent->next()->varId()) == exprVarIds.end()) {
other = true;
@ -1212,9 +1220,13 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
const Result &result1 = checkRecursive(expr, tok->tokAt(2), tok->linkAt(1), exprVarIds, local);
if (result1.type == Result::Type::READ || result1.type == Result::Type::BAILOUT)
return result1;
if (mWhat == What::ValueFlow && result1.type == Result::Type::WRITE)
mValueFlowKnown = false;
if (Token::simpleMatch(tok->linkAt(1), "} else {")) {
const Token *elseStart = tok->linkAt(1)->tokAt(2);
const Result &result2 = checkRecursive(expr, elseStart, elseStart->link(), exprVarIds, local);
if (mWhat == What::ValueFlow && result2.type == Result::Type::WRITE)
mValueFlowKnown = false;
if (result2.type == Result::Type::READ || result2.type == Result::Type::BAILOUT)
return result2;
if (result1.type == Result::Type::WRITE && result2.type == Result::Type::WRITE)
@ -1362,9 +1374,10 @@ bool FwdAnalysis::unusedValue(const Token *expr, const Token *startToken, const
return (result.type == FwdAnalysis::Result::Type::NONE || result.type == FwdAnalysis::Result::Type::RETURN) && !possiblyAliased(expr, startToken);
}
std::vector<const Token *> FwdAnalysis::valueFlow(const Token *expr, const Token *startToken, const Token *endToken)
std::vector<FwdAnalysis::KnownAndToken> FwdAnalysis::valueFlow(const Token *expr, const Token *startToken, const Token *endToken)
{
mWhat = What::ValueFlow;
mValueFlowKnown = true;
check(expr, startToken, endToken);
return mValueFlow;
}

13
lib/astutils.h
View File

@ -170,7 +170,7 @@ bool isConstVarExpression(const Token *tok);
*/
class FwdAnalysis {
public:
FwdAnalysis(bool cpp, const Library &library) : mCpp(cpp), mLibrary(library), mWhat(What::Reassign) {}
FwdAnalysis(bool cpp, const Library &library) : mCpp(cpp), mLibrary(library), mWhat(What::Reassign), mValueFlowKnown(true) {}
bool hasOperand(const Token *tok, const Token *lhs) const;
@ -192,13 +192,17 @@ public:
*/
bool unusedValue(const Token *expr, const Token *startToken, const Token *endToken);
std::vector<const Token *> valueFlow(const Token *expr, const Token *startToken, const Token *endToken);
struct KnownAndToken {
bool known;
const Token *token;
};
std::vector<KnownAndToken> valueFlow(const Token *expr, const Token *startToken, const Token *endToken);
/** Is there some possible alias for given expression */
bool possiblyAliased(const Token *expr, const Token *startToken) const;
static bool isNullOperand(const Token *expr);
private:
/** Result of forward analysis */
struct Result {
@ -217,7 +221,8 @@ private:
const bool mCpp;
const Library &mLibrary;
enum class What { Reassign, UnusedValue, ValueFlow } mWhat;
std::vector<const Token *> mValueFlow;
std::vector<KnownAndToken> mValueFlow;
bool mValueFlowKnown;
};
#endif // astutilsH

9
lib/valueflow.cpp
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@ -4683,12 +4683,9 @@ static void valueFlowFwdAnalysis(const TokenList *tokenlist, const Settings *set
while (functionScope->nestedIn && functionScope->nestedIn->isExecutable())
functionScope = functionScope->nestedIn;
const Token *endToken = functionScope->bodyEnd;
for (const Token *tok2 : fwdAnalysis.valueFlow(tok->astOperand1(), startToken, endToken)) {
const Scope *s = tok2->scope();
while (s && s != tok->scope())
s = s->nestedIn;
v.valueKind = s ? ValueFlow::Value::ValueKind::Known : ValueFlow::Value::ValueKind::Possible;
setTokenValue(const_cast<Token *>(tok2), v, settings);
for (const FwdAnalysis::KnownAndToken read : fwdAnalysis.valueFlow(tok->astOperand1(), startToken, endToken)) {
v.valueKind = read.known ? ValueFlow::Value::ValueKind::Known : ValueFlow::Value::ValueKind::Possible;
setTokenValue(const_cast<Token *>(read.token), v, settings);
}
}
}

10
test/testvalueflow.cpp
View File

@ -2436,6 +2436,16 @@ private:
ASSERT_EQUALS(true, values.front().isKnown());
ASSERT_EQUALS(true, values.front().isIntValue());
ASSERT_EQUALS(1, values.front().intvalue);
code = "void f() {\n"
" Hints hints;\n"
" hints.x = 1;\n"
" if (foo)\n"
" hints.x = 2;\n"
" x = 0 + foo.x;\n" // <- foo.x is possible 1, possible 2
"}";
values = tokenValues(code, "+");
TODO_ASSERT_EQUALS(2U, 0U, values.size()); // should be 2
}
void valueFlowSwitchVariable() {