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Fix 7843 and 7844: ValueFlow for abs (#3373) 

* Refactor: Use valueFlowForward to forward values in condition expression

* Formattting

* Make known when using bools as well

* Set abs function as always positive

* Add test

* Add valueFlowSymbolicAbs

* Set impossible values

* Fix test case

* Fix error messages

* Merge
This commit is contained in:
Paul Fultz II 2021-08-02 23:31:28 -05:00 committed by GitHub
parent c630be7f8f
commit 7be9b217e6
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2 changed files with 60 additions and 1 deletions
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39
lib/valueflow.cpp
View File

@ -1564,6 +1564,11 @@ static void valueFlowImpossibleValues(TokenList* tokenList, const Settings* sett
value.bound = ValueFlow::Value::Bound::Lower; value.bound = ValueFlow::Value::Bound::Lower;
value.setImpossible(); value.setImpossible();
setTokenValue(tok, value, settings); setTokenValue(tok, value, settings);
} else if (Token::Match(tok, "abs|labs|llabs|fabs|fabsf|fabsl (")) {
ValueFlow::Value value{-1};
value.bound = ValueFlow::Value::Bound::Upper;
value.setImpossible();
setTokenValue(tok->next(), value, settings);
} }
} }
} }
@ -4058,6 +4063,34 @@ static void valueFlowSymbolic(TokenList* tokenlist, SymbolDatabase* symboldataba
} }
} }
static void valueFlowSymbolicAbs(TokenList* tokenlist, SymbolDatabase* symboldatabase)
{
for (const Scope* scope : symboldatabase->functionScopes) {
for (Token* tok = const_cast<Token*>(scope->bodyStart); tok != scope->bodyEnd; tok = tok->next()) {
if (!Token::Match(tok, "abs|labs|llabs|fabs|fabsf|fabsl ("))
continue;
if (tok->hasKnownIntValue())
continue;
const Token* arg = tok->next()->astOperand2();
if (!arg)
continue;
ValueFlow::Value c = inferCondition(">=", arg, 0);
if (!c.isKnown())
continue;
ValueFlow::Value v = makeSymbolic(arg);
v.errorPath = c.errorPath;
v.errorPath.emplace_back(tok, "Passed to " + tok->str());
if (c.intvalue == 0)
v.setImpossible();
else
v.setKnown();
setTokenValue(tok->next(), v, tokenlist->getSettings());
}
}
}
static void valueFlowSymbolicInfer(TokenList* tokenlist, SymbolDatabase* symboldatabase) static void valueFlowSymbolicInfer(TokenList* tokenlist, SymbolDatabase* symboldatabase)
{ {
for (const Scope* scope : symboldatabase->functionScopes) { for (const Scope* scope : symboldatabase->functionScopes) {
@ -4108,6 +4141,10 @@ static void valueFlowSymbolicInfer(TokenList* tokenlist, SymbolDatabase* symbold
value.valueKind = rhs->valueKind; value.valueKind = rhs->valueKind;
value.errorPath = rhs->errorPath; value.errorPath = rhs->errorPath;
} }
if (Token::Match(tok, "%comp%") && value.isImpossible() && value.intvalue != 0) {
value.intvalue = 0;
value.setKnown();
}
setTokenValue(tok, value, tokenlist->getSettings()); setTokenValue(tok, value, tokenlist->getSettings());
} }
} }
@ -4632,7 +4669,6 @@ struct ConditionHandler {
return; return;
} }
// *INDENT-ON* // *INDENT-ON*
} }
} }
@ -7055,6 +7091,7 @@ void ValueFlow::setValues(TokenList *tokenlist, SymbolDatabase* symboldatabase,
while (n > 0 && values < getTotalValues(tokenlist)) { while (n > 0 && values < getTotalValues(tokenlist)) {
values = getTotalValues(tokenlist); values = getTotalValues(tokenlist);
valueFlowImpossibleValues(tokenlist, settings); valueFlowImpossibleValues(tokenlist, settings);
valueFlowSymbolicAbs(tokenlist, symboldatabase);
valueFlowSymbolicInfer(tokenlist, symboldatabase); valueFlowSymbolicInfer(tokenlist, symboldatabase);
valueFlowArrayBool(tokenlist); valueFlowArrayBool(tokenlist);
valueFlowRightShift(tokenlist, settings); valueFlowRightShift(tokenlist, settings);

22
test/testcondition.cpp
View File

@ -3728,6 +3728,28 @@ private:
"}\n"); "}\n");
ASSERT_EQUALS("", errout.str()); ASSERT_EQUALS("", errout.str());
// #7843
check("void f(int i) {\n"
" if(abs(i) == -1) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Condition 'abs(i)==-1' is always false\n", errout.str());
// #7844
check("void f(int i) {\n"
" if(i > 0 && abs(i) == i) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Condition 'abs(i)==i' is always true\n", errout.str());
check("void f(int i) {\n"
" if(i < 0 && abs(i) == i) {}\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (style) Condition 'abs(i)==i' is always false\n", errout.str());
check("void f(int i) {\n"
" if(i > -3 && abs(i) == i) {}\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// #9948 // #9948
check("bool f(bool a, bool b) {\n" check("bool f(bool a, bool b) {\n"
" return a || ! b || ! a;\n" " return a || ! b || ! a;\n"