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New check: use memcpy/memset instead of loop (#4257)

This commit is contained in:
Maksim Derbasov 2022-09-04 00:29:06 +03:00 committed by GitHub
parent 070bae871a
commit f93b588603
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5 changed files with 257 additions and 1 deletions
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2
lib/astutils.cpp
View File

@ -1728,6 +1728,8 @@ static bool functionModifiesArguments(const Function* f)
bool isConstFunctionCall(const Token* ftok, const Library& library)
{
if (isSizeOfEtc(ftok))
return true;
if (!Token::Match(ftok, "%name% ("))
return false;
if (const Function* f = ftok->function()) {

109
lib/checkfunctions.cpp
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@ -689,3 +689,112 @@ void CheckFunctions::copyElisionError(const Token *tok)
"Using std::move for returning object by-value from function will affect copy elision optimization."
" More: https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rf-return-move-local");
}
void CheckFunctions::useStandardLibrary()
{
if (!mSettings->severity.isEnabled(Severity::style))
return;
for (const Scope& scope: mTokenizer->getSymbolDatabase()->scopeList) {
if (scope.type != Scope::ScopeType::eFor)
continue;
const Token *forToken = scope.classDef;
// for ( initToken ; condToken ; stepToken )
const Token* initToken = getInitTok(forToken);
if (!initToken)
continue;
const Token* condToken = getCondTok(forToken);
if (!condToken)
continue;
const Token* stepToken = getStepTok(forToken);
if (!stepToken)
continue;
// 1. we expect that idx variable will be initialized with 0
const Token* idxToken = initToken->astOperand1();
const Token* initVal = initToken->astOperand2();
if (!idxToken || !initVal || !initVal->hasKnownIntValue() || initVal->getKnownIntValue() != 0)
continue;
const auto idxVarId = idxToken->varId();
if (0 == idxVarId)
continue;
// 2. we expect that idx will be less of some variable
if (!condToken->isComparisonOp())
continue;
const auto& secondOp = condToken->str();
const bool isLess = "<" == secondOp &&
isConstExpression(condToken->astOperand2(), mSettings->library, true, mTokenizer->isCPP()) &&
condToken->astOperand1()->varId() == idxVarId;
const bool isMore = ">" == secondOp &&
isConstExpression(condToken->astOperand1(), mSettings->library, true, mTokenizer->isCPP()) &&
condToken->astOperand2()->varId() == idxVarId;
if (!(isLess || isMore))
continue;
// 3. we expect idx incrementing by 1
const bool inc = stepToken->str() == "++" && stepToken->astOperand1()->varId() == idxVarId;
const bool plusOne = stepToken->isBinaryOp() && stepToken->str() == "+=" &&
stepToken->astOperand1()->varId() == idxVarId &&
stepToken->astOperand2()->str() == "1";
if (!inc && !plusOne)
continue;
// technically using void* here is not correct but some compilers could allow it
const Token *tok = scope.bodyStart;
const std::string memcpyName = mTokenizer->isCPP() ? "std::memcpy" : "memcpy";
// (reinterpret_cast<uint8_t*>(dest))[i] = (reinterpret_cast<const uint8_t*>(src))[i];
if (Token::Match(tok, "{ (| reinterpret_cast < uint8_t|int8_t|char|void * > ( %var% ) )| [ %varid% ] = "
"(| reinterpret_cast < const| uint8_t|int8_t|char|void * > ( %var% ) )| [ %varid% ] ; }", idxVarId)) {
useStandardLibraryError(tok->next(), memcpyName);
continue;
}
// ((char*)dst)[i] = ((const char*)src)[i];
if (Token::Match(tok, "{ ( ( uint8_t|int8_t|char|void * ) (| %var% ) )| [ %varid% ] = "
"( ( const| uint8_t|int8_t|char|void * ) (| %var% ) )| [ %varid% ] ; }", idxVarId)) {
useStandardLibraryError(tok->next(), memcpyName);
continue;
}
const static std::string memsetName = mTokenizer->isCPP() ? "std::memset" : "memset";
// ((char*)dst)[i] = 0;
if (Token::Match(tok, "{ ( ( uint8_t|int8_t|char|void * ) (| %var% ) )| [ %varid% ] = %char%|%num% ; }", idxVarId)) {
useStandardLibraryError(tok->next(), memsetName);
continue;
}
// ((char*)dst)[i] = (const char*)0;
if (Token::Match(tok, "{ ( ( uint8_t|int8_t|char|void * ) (| %var% ) )| [ %varid% ] = "
"( const| uint8_t|int8_t|char ) (| %char%|%num% )| ; }", idxVarId)) {
useStandardLibraryError(tok->next(), memsetName);
continue;
}
// (reinterpret_cast<uint8_t*>(dest))[i] = static_cast<const uint8_t>(0);
if (Token::Match(tok, "{ (| reinterpret_cast < uint8_t|int8_t|char|void * > ( %var% ) )| [ %varid% ] = "
"(| static_cast < const| uint8_t|int8_t|char > ( %char%|%num% ) )| ; }", idxVarId)) {
useStandardLibraryError(tok->next(), memsetName);
continue;
}
// (reinterpret_cast<int8_t*>(dest))[i] = 0;
if (Token::Match(tok, "{ (| reinterpret_cast < uint8_t|int8_t|char|void * > ( %var% ) )| [ %varid% ] = "
"%char%|%num% ; }", idxVarId)) {
useStandardLibraryError(tok->next(), memsetName);
continue;
}
}
}
void CheckFunctions::useStandardLibraryError(const Token *tok, const std::string& expected)
{
reportError(tok, Severity::style,
"useStandardLibrary",
"Consider using " + expected + " instead of loop.");
}

8
lib/checkfunctions.h
View File

@ -73,6 +73,7 @@ public:
checkFunctions.memsetZeroBytes();
checkFunctions.memsetInvalid2ndParam();
checkFunctions.returnLocalStdMove();
checkFunctions.useStandardLibrary();
}
/** Check for functions that should not be used */
@ -103,6 +104,8 @@ public:
/** @brief %Check for copy elision by RVO|NRVO */
void returnLocalStdMove();
void useStandardLibrary();
/** @brief --check-library: warn for unconfigured function calls */
void checkLibraryMatchFunctions();
@ -122,6 +125,7 @@ private:
void memsetValueOutOfRangeError(const Token *tok, const std::string &value);
void missingReturnError(const Token *tok);
void copyElisionError(const Token *tok);
void useStandardLibraryError(const Token *tok, const std::string& expected);
void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const override {
CheckFunctions c(nullptr, settings, errorLogger);
@ -141,6 +145,7 @@ private:
c.memsetValueOutOfRangeError(nullptr, "varname");
c.missingReturnError(nullptr);
c.copyElisionError(nullptr);
c.useStandardLibraryError(nullptr, "memcpy");
}
static std::string myName() {
@ -156,7 +161,8 @@ private:
"- memset() third argument is zero\n"
"- memset() with a value out of range as the 2nd parameter\n"
"- memset() with a float as the 2nd parameter\n"
"- copy elision optimization for returning value affected by std::move\n";
"- copy elision optimization for returning value affected by std::move\n"
"- use memcpy()/memset() instead of for loop\n";
}
};
/// @}

3
lib/token.h
View File

@ -401,6 +401,9 @@ public:
bool isEnumerator() const {
return mTokType == eEnumerator;
}
bool isVariable() const {
return mTokType == eVariable;
}
bool isOp() const {
return (isConstOp() ||
isAssignmentOp() ||

136
test/testfunctions.cpp
View File

@ -102,6 +102,21 @@ private:
TEST_CASE(negativeMemoryAllocationSizeError); // #389
TEST_CASE(checkLibraryMatchFunctions);
TEST_CASE(checkUseStandardLibrary1);
TEST_CASE(checkUseStandardLibrary2);
TEST_CASE(checkUseStandardLibrary3);
TEST_CASE(checkUseStandardLibrary4);
TEST_CASE(checkUseStandardLibrary5);
TEST_CASE(checkUseStandardLibrary6);
TEST_CASE(checkUseStandardLibrary7);
TEST_CASE(checkUseStandardLibrary8);
TEST_CASE(checkUseStandardLibrary9);
TEST_CASE(checkUseStandardLibrary10);
TEST_CASE(checkUseStandardLibrary11);
TEST_CASE(checkUseStandardLibrary12);
TEST_CASE(checkUseStandardLibrary13);
TEST_CASE(checkUseStandardLibrary14);
}
#define check(...) check_(__FILE__, __LINE__, __VA_ARGS__)
@ -1853,6 +1868,127 @@ private:
settings.severity = severity_old;
settings.checkLibrary = false;
}
void checkUseStandardLibrary1() {
check("void f(void* dest, void const* src, const size_t count) {\n"
" size_t i;\n"
" for (i = 0; count > i; ++i)\n"
" (reinterpret_cast<uint8_t*>(dest))[i] = (reinterpret_cast<const uint8_t*>(src))[i];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (style) Consider using std::memcpy instead of loop.\n", errout.str());
}
void checkUseStandardLibrary2() {
check("void f(void* dest, void const* src, const size_t count) {\n"
" for (size_t i = 0; i < count; i++) {\n"
" (reinterpret_cast<uint8_t*>(dest))[i] = (reinterpret_cast<const uint8_t*>(src))[i];\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memcpy instead of loop.\n", errout.str());
}
void checkUseStandardLibrary3() {
check("void f(void* dst, const void* src, const size_t count) {\n"
" size_t i;\n"
" for (i = 0; count > i; i++)\n"
" ((char*)dst)[i] = ((const char*)src)[i];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (style) Consider using std::memcpy instead of loop.\n", errout.str());
}
void checkUseStandardLibrary4() {
check("void f(void* dst, void* src, const size_t size) {\n"
" for (size_t i = 0; i < size; i += 1) {\n"
" ((int8_t*)dst)[i] = ((int8_t*)src)[i];\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memcpy instead of loop.\n", errout.str());
}
// different indexes
void checkUseStandardLibrary5() {
check("void f(void* dst, void* src, const size_t size, const size_t from_idx) {\n"
" for (size_t i = 0; i < size; ++i) {\n"
" ((int8_t*)dst)[i] = ((int8_t*)src)[from_idx];\n"
"}}\n");
ASSERT_EQUALS("", errout.str());
}
// unknown count
void checkUseStandardLibrary6() {
check("void f(void* dst, void* src, const size_t size) {\n"
" for (size_t i = 0; ((int8_t*)src)[i] != 0; ++i) {\n"
" ((int8_t*)dst)[i] = ((int8_t*)src)[i];\n"
"}}\n");
ASSERT_EQUALS("", errout.str());
}
// increment with 2
void checkUseStandardLibrary7() {
check("void f(void* dst, void* src, const size_t size) {\n"
" for (size_t i = 0; i < size; i += 2) {\n"
" ((int8_t*)dst)[i] = ((int8_t*)src)[i];\n"
"}}\n");
ASSERT_EQUALS("", errout.str());
}
// right argument of assignment could be static_cast, functional cast, c-style and implicit cast
// functional cast case not covered
void checkUseStandardLibrary8() {
check("void f(void* dest, const size_t count) {\n"
" size_t i;\n"
" for (i = 0; i < count; ++i)\n"
" (reinterpret_cast<int8_t*>(dest))[i] = static_cast<const int8_t>(0);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
void checkUseStandardLibrary9() {
check("void f(void* dest, const size_t count) {\n"
" for (size_t i = 0; i < count; i++) {\n"
" (reinterpret_cast<uint8_t*>(dest))[i] = (static_cast<const uint8_t>(0));\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
void checkUseStandardLibrary10() {
check("void f(void* dst, const size_t size) {\n"
" size_t i;\n"
" for (i = 0; i < size; i++)\n"
" ((char*)dst)[i] = (const char)0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
void checkUseStandardLibrary11() {
check("void f(void* dst, const size_t size) {\n"
" for (size_t i = 0; i < size; i += 1) {\n"
" ((int8_t*)dst)[i] = ((int8_t)0);\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
void checkUseStandardLibrary12() {
check("void f(void* dst, const size_t size) {\n"
" for (size_t i = 0; i < size; i += 1) {\n"
" ((int8_t*)dst)[i] = 42;\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
void checkUseStandardLibrary13() {
check("void f(void* dest, const size_t count) {\n"
" for (size_t i = 0; i < count; i++) {\n"
" reinterpret_cast<unsigned char*>(dest)[i] = '0';\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
void checkUseStandardLibrary14() {
check("void f(void* dest) {\n"
" for (size_t i = 0; i < sizeof(int)*(15 + 42/2 - 7); i++) {\n"
" reinterpret_cast<unsigned char*>(dest)[i] = '0';\n"
"}}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Consider using std::memset instead of loop.\n", errout.str());
}
};
REGISTER_TEST(TestFunctions)