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Clarify FwdAnalysis. It is useful for checks that need data flow analysis of ALL paths.

This commit is contained in:
Daniel Marjamäki 2018-12-25 11:56:06 +01:00
parent c7993df4ff
commit ddbe5c129c
4 changed files with 24 additions and 19 deletions
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26
lib/astutils.cpp
View File

@ -1083,7 +1083,7 @@ static bool hasFunctionCall(const Token *tok)
return hasFunctionCall(tok->astOperand1()) || hasFunctionCall(tok->astOperand2());
}
struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const Token *startToken, const Token *endToken, const std::set<unsigned int> &exprVarIds, bool local)
struct FwdAnalysisAllPaths::Result FwdAnalysisAllPaths::checkRecursive(const Token *expr, const Token *startToken, const Token *endToken, const std::set<unsigned int> &exprVarIds, bool local)
{
// Parse the given tokens
for (const Token *tok = startToken; tok != endToken; tok = tok->next()) {
@ -1141,7 +1141,7 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
}
// check loop body again..
const struct FwdAnalysis::Result &result = checkRecursive(expr, tok->link(), tok, exprVarIds, local);
const struct FwdAnalysisAllPaths::Result &result = checkRecursive(expr, tok->link(), tok, exprVarIds, local);
if (result.type == Result::Type::BAILOUT || result.type == Result::Type::READ)
return result;
}
@ -1221,7 +1221,7 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
return Result(Result::Type::NONE);
}
bool FwdAnalysis::isGlobalData(const Token *expr) const
bool FwdAnalysisAllPaths::isGlobalData(const Token *expr) const
{
bool globalData = false;
visitAstNodes(expr,
@ -1289,7 +1289,7 @@ bool FwdAnalysis::isGlobalData(const Token *expr) const
return globalData;
}
FwdAnalysis::Result FwdAnalysis::check(const Token *expr, const Token *startToken, const Token *endToken)
FwdAnalysisAllPaths::Result FwdAnalysisAllPaths::check(const Token *expr, const Token *startToken, const Token *endToken)
{
// all variable ids in expr.
std::set<unsigned int> exprVarIds;
@ -1314,12 +1314,12 @@ FwdAnalysis::Result FwdAnalysis::check(const Token *expr, const Token *startToke
// In unused values checking we do not want to check assignments to
// global data.
if (mWhat == What::UnusedValue && isGlobalData(expr))
return Result(FwdAnalysis::Result::Type::BAILOUT);
return Result(FwdAnalysisAllPaths::Result::Type::BAILOUT);
Result result = checkRecursive(expr, startToken, endToken, exprVarIds, local);
// Break => continue checking in outer scope
while (result.type == FwdAnalysis::Result::Type::BREAK) {
while (result.type == FwdAnalysisAllPaths::Result::Type::BREAK) {
const Scope *s = result.token->scope();
while (s->type == Scope::eIf)
s = s->nestedIn;
@ -1331,7 +1331,7 @@ FwdAnalysis::Result FwdAnalysis::check(const Token *expr, const Token *startToke
return result;
}
bool FwdAnalysis::hasOperand(const Token *tok, const Token *lhs) const
bool FwdAnalysisAllPaths::hasOperand(const Token *tok, const Token *lhs) const
{
if (!tok)
return false;
@ -1340,21 +1340,21 @@ bool FwdAnalysis::hasOperand(const Token *tok, const Token *lhs) const
return hasOperand(tok->astOperand1(), lhs) || hasOperand(tok->astOperand2(), lhs);
}
const Token *FwdAnalysis::reassign(const Token *expr, const Token *startToken, const Token *endToken)
const Token *FwdAnalysisAllPaths::reassign(const Token *expr, const Token *startToken, const Token *endToken)
{
mWhat = What::Reassign;
Result result = check(expr, startToken, endToken);
return result.type == FwdAnalysis::Result::Type::WRITE ? result.token : nullptr;
return result.type == FwdAnalysisAllPaths::Result::Type::WRITE ? result.token : nullptr;
}
bool FwdAnalysis::unusedValue(const Token *expr, const Token *startToken, const Token *endToken)
bool FwdAnalysisAllPaths::unusedValue(const Token *expr, const Token *startToken, const Token *endToken)
{
mWhat = What::UnusedValue;
Result result = check(expr, startToken, endToken);
return (result.type == FwdAnalysis::Result::Type::NONE || result.type == FwdAnalysis::Result::Type::RETURN) && !possiblyAliased(expr, startToken);
return (result.type == FwdAnalysisAllPaths::Result::Type::NONE || result.type == FwdAnalysisAllPaths::Result::Type::RETURN) && !possiblyAliased(expr, startToken);
}
bool FwdAnalysis::possiblyAliased(const Token *expr, const Token *startToken) const
bool FwdAnalysisAllPaths::possiblyAliased(const Token *expr, const Token *startToken) const
{
if (expr->isUnaryOp("*"))
return true;
@ -1384,7 +1384,7 @@ bool FwdAnalysis::possiblyAliased(const Token *expr, const Token *startToken) co
return false;
}
bool FwdAnalysis::isNullOperand(const Token *expr)
bool FwdAnalysisAllPaths::isNullOperand(const Token *expr)
{
if (!expr)
return false;

9
lib/astutils.h
View File

@ -162,9 +162,14 @@ bool isLikelyStreamRead(bool cpp, const Token *op);
bool isConstVarExpression(const Token *tok);
class FwdAnalysis {
/**
* Forward data flow analysis for checks that investigate ALL paths.
* - unused value
* - redundant assignment
*/
class FwdAnalysisAllPaths {
public:
FwdAnalysis(bool cpp, const Library &library) : mCpp(cpp), mLibrary(library), mWhat(What::Reassign) {}
FwdAnalysisAllPaths(bool cpp, const Library &library) : mCpp(cpp), mLibrary(library), mWhat(What::Reassign) {}
bool hasOperand(const Token *tok, const Token *lhs) const;

4
lib/checkother.cpp
View File

@ -449,7 +449,7 @@ void CheckOther::checkRedundantAssignment()
}
// Do not warn about assignment with 0 / NULL
if (Token::simpleMatch(tok->astOperand2(), "0") || FwdAnalysis::isNullOperand(tok->astOperand2()))
if (Token::simpleMatch(tok->astOperand2(), "0") || FwdAnalysisAllPaths::isNullOperand(tok->astOperand2()))
continue;
if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isReference())
@ -474,7 +474,7 @@ void CheckOther::checkRedundantAssignment()
if (inconclusive && !mSettings->inconclusive)
continue;
FwdAnalysis fwdAnalysis(mTokenizer->isCPP(), mSettings->library);
FwdAnalysisAllPaths fwdAnalysis(mTokenizer->isCPP(), mSettings->library);
if (fwdAnalysis.hasOperand(tok->astOperand2(), tok->astOperand1()))
continue;

4
lib/checkunusedvar.cpp
View File

@ -1134,7 +1134,7 @@ void CheckUnusedVar::checkFunctionVariableUsage()
continue;
}
// Do not warn about assignment with NULL
if (FwdAnalysis::isNullOperand(tok->astOperand2()))
if (FwdAnalysisAllPaths::isNullOperand(tok->astOperand2()))
continue;
if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isReference() && tok->astOperand1()->variable()->nameToken() != tok->astOperand1())
@ -1153,7 +1153,7 @@ void CheckUnusedVar::checkFunctionVariableUsage()
const Token *expr = varDecl ? varDecl : tok->astOperand1();
FwdAnalysis fwdAnalysis(mTokenizer->isCPP(), mSettings->library);
FwdAnalysisAllPaths fwdAnalysis(mTokenizer->isCPP(), mSettings->library);
if (fwdAnalysis.unusedValue(expr, start, scope->bodyEnd))
// warn
unreadVariableError(tok, expr->expressionString(), false);