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- #7522 and #7428 revisited. ((a&7)>7U) is always false and ((X|7)>=6) is correct (X can be negative).

This commit is contained in:
Bartlomiej Grzeskowiak 2016-06-17 12:12:53 +02:00
parent 7466a49b21
commit a5cfa2b12c
2 changed files with 72 additions and 31 deletions
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11
lib/checkcondition.cpp
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@ -281,7 +281,7 @@ void CheckCondition::comparison()
return;
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
if (Token::Match(tok, "==|!=|>|>=|<|<=")) {
if (Token::Match(tok, "==|!=|>")) {
const Token *expr1 = tok->astOperand1();
const Token *expr2 = tok->astOperand2();
if (!expr1 || !expr2)
@ -301,22 +301,17 @@ void CheckCondition::comparison()
const MathLib::bigint num1 = *num;
if (num1 < 0)
continue;
if (Token::Match(tok, "==|!=|>=|<=")) {
if (Token::Match(tok, "==|!=")) {
if ((expr1->str() == "&" && (num1 & num2) != num2) ||
(expr1->str() == "|" && (num1 | num2) != num2)) {
const std::string& op(tok->str());
comparisonError(expr1, expr1->str(), num1, op, num2, op!="!=" ? false : true);
comparisonError(expr1, expr1->str(), num1, op, num2, op=="==" ? false : true);
}
} else if (Token::simpleMatch(tok, ">")) {
if ((expr1->str() == "&" && (num1 <= num2))) {
const std::string& op(tok->str());
comparisonError(expr1, expr1->str(), num1, op, num2, false);
}
} else if (Token::simpleMatch(tok, "<")) {
if ((expr1->str() == "|" && (num1 >= num2))) {
const std::string& op(tok->str());
comparisonError(expr1, expr1->str(), num1, op, num2, false);
}
}
}
}

92
test/testcondition.cpp
View File

@ -591,6 +591,75 @@ private:
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
//Various bitmask comparison checks
//#7428 false negative: condition '(a&7)>7U' is always false
//#7522 false positive: condition '(X|7)>=6' is correct
check("void f() {\n"
"assert( (a & 0x07) == 8U );\n" // statement always false
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Expression '(X & 0x7) == 0x8' is always false.\n",
errout.str());
check("void f() {\n"
"assert( (a & 0x07) == 7U );\n" // statement correct
"assert( (a & 0x07) == 6U );\n" // statement correct
"}");
ASSERT_EQUALS("", errout.str());
check("void f() {\n"
"assert( (a | 0x07) == 8U );\n" // statement always false
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Expression '(X | 0x7) == 0x8' is always false.\n",
errout.str());
check("void f() {\n"
"assert( (a | 0x07) == 7U );\n" // statement correct
"assert( (a | 0x07) == 23U );\n" // statement correct
"}");
ASSERT_EQUALS("", errout.str());
check("void f() {\n"
"assert( (a & 0x07) != 8U );\n" // statement always true
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Expression '(X & 0x7) != 0x8' is always true.\n",
errout.str());
check("void f() {\n"
"assert( (a & 0x07) != 7U );\n" // statement correct
"assert( (a & 0x07) != 0U );\n" // statement correct
"}");
ASSERT_EQUALS("", errout.str());
check("void f() {\n"
"assert( (a | 0x07) != 8U );\n" // statement always true
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Expression '(X | 0x7) != 0x8' is always true.\n",
errout.str());
check("void f() {\n"
"assert( (a | 0x07) != 7U );\n" // statement correct
"}");
ASSERT_EQUALS("", errout.str());
//TRAC #7428 false negative: condition '(X&7)>7' is always false
check("void f() {\n"
"assert( (a & 0x07) > 7U );\n" // statement always false
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Expression '(X & 0x7) > 0x7' is always false.\n",
errout.str());
check("void f() {\n"
"assert( (a & 0x07) > 6U );\n" // statement correct
"}");
ASSERT_EQUALS("", errout.str());
//TRAC #7522 false positive: condition '(X|7)>=6' is correct (X can be negative)
check("void f() {\n"
"assert( (a | 0x07) >= 6U );\n" // statement correct (X can be negative)
"}");
ASSERT_EQUALS("",errout.str());
}
@ -1651,29 +1720,6 @@ private:
" assert(x == 0);\n"
"}");
ASSERT_EQUALS("", errout.str());
//TRAC #7428 false negative: Statement is always false
check("void f() {\n"
"assert( (a & 0x07) == 8U );\n" // statement always false, because 7 == 8 is false
"assert( (a & 0x07) > 7U );\n" // statement always false, because 7 > 7 is false
"assert( (a | 0x07) < 7U );\n" // statement always false, because 7 < 7 is false
"assert( (a & 0x07) > 8U );\n" // statement always false, because 7 > 8 is false
"assert( (a | 0x07) < 6U );\n" // statement always false, because 7 < 6 is false
"assert( (a & 0x07) >= 7U );\n" // statement correct
"assert( (a | 0x07) <= 7U );\n" // statement correct
"assert( (a & 0x07) >= 8U );\n" // statement always false, because 7 >= 8 is false
"assert( (a | 0x07) <= 6U );\n" // statement always false, because 7 <= 6 is false
"assert( (a & 0x07) > 3U );\n" // statement correct
"assert( (a | 0x07) < 9U );\n" // statement correct
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Expression '(X & 0x7) == 0x8' is always false.\n"
"[test.cpp:3]: (style) Expression '(X & 0x7) > 0x7' is always false.\n"
"[test.cpp:4]: (style) Expression '(X | 0x7) < 0x7' is always false.\n"
"[test.cpp:5]: (style) Expression '(X & 0x7) > 0x8' is always false.\n"
"[test.cpp:6]: (style) Expression '(X | 0x7) < 0x6' is always false.\n"
"[test.cpp:9]: (style) Expression '(X & 0x7) >= 0x8' is always false.\n"
"[test.cpp:10]: (style) Expression '(X | 0x7) <= 0x6' is always false.\n",
errout.str());
}
void checkInvalidTestForOverflow() {