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value flow: if unsigned variable is compared against 1 with either >= or <= then assume it can have the value 0

This commit is contained in:
Daniel Marjamäki 2014-01-08 06:53:17 +01:00
parent 1e3c43e708
commit 6d22c9deaa
3 changed files with 13 additions and 0 deletions
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5
lib/valueflow.cpp
View File

@ -86,6 +86,9 @@ static void valueFlowBeforeCondition(TokenList *tokenlist, ErrorLogger *errorLog
}
const ValueFlow::Value val(tok, num);
ValueFlow::Value val2;
if (num==1 && var->typeStartToken()->isUnsigned() && Token::Match(tok,"<=|>="))
val2 = ValueFlow::Value(tok,0);
for (Token *tok2 = tok->previous(); ; tok2 = tok2->previous()) {
if (!tok2) {
@ -117,6 +120,8 @@ static void valueFlowBeforeCondition(TokenList *tokenlist, ErrorLogger *errorLog
}
tok2->values.push_back(val);
if (val2.condition)
tok2->values.push_back(val2);
if (var && tok2 == var->nameToken())
break;
}

1
test/testother.cpp
View File

@ -210,6 +210,7 @@ private:
settings->inconclusive = inconclusive;
settings->experimental = experimental;
settings->standards.posix = posix;
settings->valueFlow = true;
if (posix) {
const char cfg[] = "<?xml version=\"1.0\"?>\n"

7
test/testvalueflow.cpp
View File

@ -84,6 +84,13 @@ private:
"}";
ASSERT_EQUALS(true, testValueOfX(code, 2U, 123));
code = "void f(unsigned int x) {\n"
" int a = x;\n"
" if (x >= 1) {}\n"
"}";
ASSERT_EQUALS(true, testValueOfX(code, 2U, 1));
ASSERT_EQUALS(true, testValueOfX(code, 2U, 0));
// bailout: ?:
bailout("void f(int x) {\n"
" y = ((x<0) ? x : ((x==2)?3:4));\n"