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Improved check: Detect passedByValue even for arguments that are not declared as "const"

This commit is contained in:
PKEuS 2016-07-28 13:19:24 +02:00 committed by PKEuS
parent 0777ecd071
commit 452ecc7ceb
3 changed files with 233 additions and 23 deletions
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121
lib/checkother.cpp
View File

@ -1383,9 +1383,39 @@ void CheckOther::commaSeparatedReturnError(const Token *tok)
}
//---------------------------------------------------------------------------
// Check for constant function parameters
// Check for function parameters that should be passed by reference
//---------------------------------------------------------------------------
void CheckOther::checkConstantFunctionParameter()
static std::size_t estimateSize(const Type* type, const Settings* settings, const SymbolDatabase* symbolDatabase, std::size_t recursionDepth = 0)
{
if (recursionDepth > 20)
return 0;
std::size_t cumulatedSize = 0;
for (std::list<Variable>::const_iterator i = type->classScope->varlist.cbegin(); i != type->classScope->varlist.cend(); ++i) {
std::size_t size = 0;
if (i->isStatic())
continue;
if (i->isPointer() || i->isReference())
size = settings->sizeof_pointer;
else if (i->type() && i->type()->classScope)
size = estimateSize(i->type(), settings, symbolDatabase, recursionDepth+1);
else if (i->isStlStringType() || (i->isStlType() && Token::Match(i->typeStartToken(), "std :: %type% <") && !Token::simpleMatch(i->typeStartToken()->linkAt(3), "> ::")))
size = 16; // Just guess
else
size = symbolDatabase->sizeOfType(i->typeStartToken());
if (i->isArray())
cumulatedSize += size*i->dimension(0);
else
cumulatedSize += size;
}
for (std::vector<Type::BaseInfo>::const_iterator i = type->derivedFrom.cbegin(); i != type->derivedFrom.cend(); ++i)
if (i->type && i->type->classScope)
cumulatedSize += estimateSize(i->type, settings, symbolDatabase, recursionDepth+1);
return cumulatedSize;
}
void CheckOther::checkPassByReference()
{
if (!_settings->isEnabled("performance") || _tokenizer->isC())
return;
@ -1394,34 +1424,97 @@ void CheckOther::checkConstantFunctionParameter()
for (unsigned int i = 1; i < symbolDatabase->getVariableListSize(); i++) {
const Variable* var = symbolDatabase->getVariableFromVarId(i);
if (!var || !var->isArgument() || !var->isClass() || !var->isConst() || var->isPointer() || var->isArray() || var->isReference() || var->isEnumType())
if (!var || !var->isArgument() || !var->isClass() || var->isPointer() || var->isArray() || var->isReference() || var->isEnumType())
continue;
if (var->scope() && var->scope()->function->arg->link()->strAt(-1) == ".")
continue; // references could not be used as va_start parameters (#5824)
bool inconclusive = false;
const Token* const tok = var->typeStartToken();
// TODO: False negatives. This pattern only checks for string.
// Investigate if there are other classes in the std
// namespace and add them to the pattern. There are
// streams for example (however it seems strange with
// const stream parameter).
if (var->isStlStringType()) {
passedByValueError(tok, var->name());
;
} else if (var->isStlType() && Token::Match(tok, "std :: %type% <") && !Token::simpleMatch(tok->linkAt(3), "> ::")) {
passedByValueError(tok, var->name());
} else if (var->type()) { // Check if type is a struct or class.
passedByValueError(tok, var->name());
;
} else if (var->type() && !var->type()->isEnumType()) { // Check if type is a struct or class.
// Ensure that it is a large object.
if (!var->type()->classScope)
inconclusive = true;
else if (estimateSize(var->type(), _settings, symbolDatabase) <= 8)
continue;
} else
continue;
if (inconclusive && !_settings->inconclusive)
continue;
bool isConst = var->isConst();
if (!isConst) {
// Check if variable could be const
if (!var->scope() || var->scope()->function->isVirtual())
continue;
isConst = true;
for (const Token* tok2 = var->scope()->classStart; tok2 != var->scope()->classEnd; tok2 = tok2->next()) {
if (tok2->varId() == var->declarationId()) {
const Token* parent = tok2->astParent();
if (!parent)
;
else if (parent->str() == "<<" || parent->str() == ">>") {
if (parent->str() == "<<" && parent->astOperand1() == tok2)
isConst = false;
else if (parent->str() == ">>" && parent->astOperand2() == tok2)
isConst = false;
} else if (parent->str() == "," || parent->str() == "(") { // function argument
const Token* tok3 = tok2->previous();
unsigned int argNr = 0;
while (tok3 && tok3->str() != "(") {
if (tok3->link() && Token::Match(tok3, ")|]|}|>"))
tok3 = tok3->link();
else if (tok->link())
break;
else if (tok3->str() == ";")
break;
else if (tok3->str() == ",")
argNr++;
tok3 = tok3->previous();
}
if (!tok3 || tok3->str() != "(" || !tok3->astOperand1() || !tok3->astOperand1()->function())
isConst = false;
else {
const Variable* argVar = tok3->astOperand1()->function()->getArgumentVar(argNr);
if (!argVar|| (!argVar->isConst() && argVar->isReference()))
isConst = false;
}
} else if (parent->isConstOp())
;
else if (Token::Match(tok2, "%var% . %name% (")) {
const Function* func = tok2->tokAt(2)->function();
if (func && (func->isConst() || func->isStatic()))
;
else
isConst = false;
} else
isConst = false;
if (!isConst)
break;
}
}
}
void CheckOther::passedByValueError(const Token *tok, const std::string &parname)
if (isConst)
passedByValueError(tok, var->name(), inconclusive);
}
}
void CheckOther::passedByValueError(const Token *tok, const std::string &parname, bool inconclusive)
{
reportError(tok, Severity::performance, "passedByValue",
"Function parameter '" + parname + "' should be passed by reference.\n"
"Parameter '" + parname + "' is passed by value. It could be passed "
"as a (const) reference which is usually faster and recommended in C++.", CWE398, false);
"as a (const) reference which is usually faster and recommended in C++.", CWE398, inconclusive);
}
//---------------------------------------------------------------------------

12
lib/checkother.h
View File

@ -81,7 +81,7 @@ public:
// Checks
checkOther.clarifyCalculation();
checkOther.clarifyStatement();
checkOther.checkConstantFunctionParameter();
checkOther.checkPassByReference();
checkOther.checkIncompleteStatement();
checkOther.checkCastIntToCharAndBack();
@ -115,8 +115,8 @@ public:
/** @brief %Check for comma separated statements in return */
void checkCommaSeparatedReturn();
/** @brief %Check for constant function parameter */
void checkConstantFunctionParameter();
/** @brief %Check for function parameters that should be passed by reference */
void checkPassByReference();
/** @brief Using char variable as array index / as operand in bit operation */
void checkCharVariable();
@ -212,7 +212,7 @@ private:
void clarifyStatementError(const Token* tok);
void cstyleCastError(const Token *tok);
void invalidPointerCastError(const Token* tok, const std::string& from, const std::string& to, bool inconclusive);
void passedByValueError(const Token *tok, const std::string &parname);
void passedByValueError(const Token *tok, const std::string &parname, bool inconclusive);
void constStatementError(const Token *tok, const std::string &type);
void signedCharArrayIndexError(const Token *tok);
void unknownSignCharArrayIndexError(const Token *tok);
@ -274,7 +274,7 @@ private:
c.checkComparisonFunctionIsAlwaysTrueOrFalseError(nullptr, "isless","varName",false);
c.checkCastIntToCharAndBackError(nullptr, "func_name");
c.cstyleCastError(nullptr);
c.passedByValueError(nullptr, "parametername");
c.passedByValueError(nullptr, "parametername", false);
c.constStatementError(nullptr, "type");
c.signedCharArrayIndexError(nullptr);
c.unknownSignCharArrayIndexError(nullptr);
@ -335,6 +335,7 @@ private:
// performance
"- redundant data copying for const variable\n"
"- subsequent assignment or copying to a variable or buffer\n"
"- passing parameter by value\n"
// portability
"- memset() with a float as the 2nd parameter\n"
@ -343,7 +344,6 @@ private:
// style
"- C-style pointer cast in C++ code\n"
"- casting between incompatible pointer types\n"
"- passing parameter by value\n"
"- [Incomplete statement](IncompleteStatement)\n"
"- [check how signed char variables are used](CharVar)\n"
"- variable scope can be limited\n"

123
test/testother.cpp
View File

@ -82,6 +82,7 @@ private:
TEST_CASE(invalidPointerCast);
TEST_CASE(passedByValue);
TEST_CASE(passedByValue_nonConst);
TEST_CASE(switchRedundantAssignmentTest);
TEST_CASE(switchRedundantOperationTest);
@ -1292,7 +1293,28 @@ private:
check("void f(const std::string::size_type x) {}");
ASSERT_EQUALS("", errout.str());
check("class Foo;\nvoid f(const Foo foo) {}");
check("class Foo;\nvoid f(const Foo foo) {}"); // Unknown class
ASSERT_EQUALS("[test.cpp:2]: (performance, inconclusive) Function parameter 'foo' should be passed by reference.\n", errout.str());
check("class Foo { std::vector<int> v; };\nvoid f(const Foo foo) {}"); // Large class (STL member)
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'foo' should be passed by reference.\n", errout.str());
check("class Foo { int i; };\nvoid f(const Foo foo) {}"); // Small class
ASSERT_EQUALS("", errout.str());
check("class Foo { int i[6]; };\nvoid f(const Foo foo) {}"); // Large class (array)
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'foo' should be passed by reference.\n", errout.str());
check("class Foo { std::string* s; };\nvoid f(const Foo foo) {}"); // Small class (pointer)
ASSERT_EQUALS("", errout.str());
check("class Foo { static std::string s; };\nvoid f(const Foo foo) {}"); // Small class (static member)
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'foo' should be passed by reference.\n", errout.str());
check("class X { std::string s; }; class Foo : X { };\nvoid f(const Foo foo) {}"); // Large class (inherited)
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'foo' should be passed by reference.\n", errout.str());
check("class X { std::string s; }; class Foo { X x; };\nvoid f(const Foo foo) {}"); // Large class (inherited)
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'foo' should be passed by reference.\n", errout.str());
check("void f(const std::string &str) {}");
@ -1341,10 +1363,105 @@ private:
"}; ");
ASSERT_EQUALS("", errout.str());
check("class X {\n"
" virtual void func(const std::string str) {}\n"
"};");
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
}
void passedByValue_nonConst() {
check("void f(std::string str) {}");
ASSERT_EQUALS("[test.cpp:1]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("void f(std::string str) {\n"
" return str + x;\n"
"}");
ASSERT_EQUALS("[test.cpp:1]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("void f(std::string str) {\n"
" std::cout << str;\n"
"}");
ASSERT_EQUALS("[test.cpp:1]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("void f(std::string str) {\n"
" std::cin >> str;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void f(std::string str) {\n"
" foo(str);\n" // It could be that foo takes str as non-const-reference
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(const std::string& str);\n"
"void f(std::string str) {\n"
" foo(str);\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("void foo(std::string str);\n"
"void f(std::string str) {\n"
" foo(str);\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("void foo(std::string& str);\n"
"void f(std::string str) {\n"
" foo(str);\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int& i1, const std::string& str, int& i2);\n"
"void f(std::string str) {\n"
" foo((a+b)*c, str, x);\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("std::string f(std::string str) {\n"
" str += x;\n"
" return str;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("class X {\n"
" std::string s;\n"
" void func() const;\n"
"};\n"
"Y f(X x) {\n"
" x.func();\n"
"}");
ASSERT_EQUALS("[test.cpp:5]: (performance) Function parameter 'x' should be passed by reference.\n", errout.str());
check("class X {\n"
" void func();\n"
"};\n"
"Y f(X x) {\n"
" x.func();\n"
"}");
ASSERT_EQUALS("", errout.str());
check("class X {\n"
" void func(std::string str) {}\n"
"};");
ASSERT_EQUALS("[test.cpp:2]: (performance) Function parameter 'str' should be passed by reference.\n", errout.str());
check("class X {\n"
" virtual void func(std::string str) {}\n" // Do not warn about virtual functions, if 'str' is not declared as const
"};");
ASSERT_EQUALS("", errout.str());
check("class X {\n"
" uint64_t i;\n"
"};\n"
"class Y : X {\n"
" uint64_t j;\n"
"};\n"
"void f(X x, Y y) {\n"
"}");
ASSERT_EQUALS("[test.cpp:7]: (performance) Function parameter 'y' should be passed by reference.\n", errout.str());
}
void switchRedundantAssignmentTest() {
check("void foo()\n"
"{\n"
" int y = 1;\n"
@ -3436,7 +3553,7 @@ private:
"}");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (style) Same expression on both sides of '|'.\n", errout.str());
check("void foo(std::string a, std::string b) {\n"
check("void foo(const std::string& a, const std::string& b) {\n"
" return a.find(b+\"&\") || a.find(\"&\"+b);\n"
"}");
ASSERT_EQUALS("", errout.str());