static int doAssignment(Variables &variables, const Token *tok, bool dereference, const Scope *scope)
{
// a = a + b;
if (Token::Match(tok, "%var% = %var% !!;") && tok->str() == tok->strAt(2)) {
return 2;
}
int next = 0;
// check for aliased variable
const unsigned int varid1 = tok->varId();
Variables::VariableUsage *var1 = variables.find(varid1);
if (var1) {
Variables::VariableUsage *var2 = 0;
int start = 1;
// search for '='
while (tok->strAt(start) != "=")
start++;
start++;
if (Token::Match(tok->tokAt(start), "&| %var%") ||
Token::Match(tok->tokAt(start), "( const| struct|union| %type% *| ) &| %var%") ||
Token::Match(tok->tokAt(start), "( const| struct|union| %type% *| ) ( &| %var%") ||
Token::Match(tok->tokAt(start+1), "< const| struct|union| %type% *| > ( &| %var%")) {
unsigned char offset = 0;
unsigned int varid2;
bool addressOf = false;
if (Token::Match(tok->tokAt(start), "%var% ."))
variables.use(tok->tokAt(start)->varId()); // use = read + write
// check for C style cast
if (tok->strAt(start) == "(") {
if (tok->strAt(start + 1) == "const")
offset++;
if (Token::Match(tok->tokAt(start + 1 + offset), "struct|union"))
offset++;
if (tok->strAt(start + 2 + offset) == "*")
offset++;
if (tok->strAt(start + 3 + offset) == "&") {
addressOf = true;
next = start + 4 + offset;
} else if (tok->strAt(start + 3 + offset) == "(") {
if (tok->strAt(start + 4 + offset) == "&") {
addressOf = true;
next = start + 5 + offset;
} else
next = start + 4 + offset;
} else
next = start + 3 + offset;
}
// check for C++ style cast
else if (tok->strAt(start).find("cast") != std::string::npos &&
tok->strAt(start + 1) == "<") {
if (tok->strAt(start + 2) == "const")
offset++;
if (Token::Match(tok->tokAt(start + 2 + offset), "struct|union"))
offset++;
if (tok->strAt(start + 3 + offset) == "*")
offset++;
if (tok->strAt(start + 5 + offset) == "&") {
addressOf = true;
next = start + 6 + offset;
} else
next = start + 5 + offset;
}
// check for var ? ...
else if (Token::Match(tok->tokAt(start), "%var% ?")) {
next = start;
}
// no cast
else {
if (tok->strAt(start) == "&") {
addressOf = true;
next = start + 1;
} else if (tok->strAt(start) == "new")
return 0;
else
next = start;
}
// check if variable is local
varid2 = tok->tokAt(next)->varId();
var2 = variables.find(varid2);
if (var2) { // local variable (alias or read it)
if (var1->_type == Variables::pointer) {
if (dereference)
variables.read(varid2);
else {
if (addressOf ||
var2->_type == Variables::array ||
var2->_type == Variables::pointer) {
bool replace = true;
// check if variable declared in same scope
if (scope == var1->_scope)
replace = true;
// not in same scope as declaration
else {
// no other assignment in this scope
if (var1->_assignments.find(scope) == var1->_assignments.end()) {
// nothing to replace
if (var1->_assignments.empty())
replace = false;
// this variable has previous assignments
else {
/**
* @todo determine if existing aliases should be replaced or merged
*/
replace = false;
}
}
// assignment in this scope
else {
// replace when only one other assignment
if (var1->_assignments.size() == 1)
replace = true;
// otherwise, merge them
else
replace = false;
}
}
variables.alias(varid1, varid2, replace);
} else if (tok->strAt(next + 1) == "?") {
if (var2->_type == Variables::reference)
variables.readAliases(varid2);
else
variables.read(varid2);
}
}
} else if (var1->_type == Variables::reference) {
variables.alias(varid1, varid2, true);
} else {
if (var2->_type == Variables::pointer && tok->strAt(next + 1) == "[")
variables.readAliases(varid2);
variables.read(varid2);
}
} else { // not a local variable (or an unsupported local variable)
if (var1->_type == Variables::pointer && !dereference) {
// check if variable declaration is in this scope
if (var1->_scope == scope)
variables.clearAliases(varid1);
else {
// no other assignment in this scope
if (var1->_assignments.find(scope) == var1->_assignments.end()) {
/**
* @todo determine if existing aliases should be discarded
*/
}
// this assignment replaces the last assignment in this scope
else {
// aliased variables in a larger scope are not supported
// remove all aliases
variables.clearAliases(varid1);
}
}
}
}
}
var1->_assignments.insert(scope);
}
// check for alias to struct member
// char c[10]; a.b = c;
else if (Token::Match(tok->tokAt(-2), "%var% .")) {
if (Token::Match(tok->tokAt(2), "%var%")) {
unsigned int varid2 = tok->tokAt(2)->varId();
Variables::VariableUsage *var2 = variables.find(varid2);
// struct member aliased to local variable
if (var2 && (var2->_type == Variables::array ||
var2->_type == Variables::pointer)) {
// erase aliased variable and all variables that alias it
// to prevent false positives
variables.eraseAll(varid2);
}
}
}
return next;
}
