In the following JavaScript code, both of the print calls must print out "undefined" because of "x" is a formal parameter. But the second print call prints out "function x() { }". This bug may lead to type confusion in JITed code.
```
function f(x) {
print(x);
{
function x() {
}
}
print(x);
}
```
The following code in "PreVisitFunction" is used to decide how to optimize arguments.
```
bool doStackArgsOpt = (!pnode->sxFnc.HasAnyWriteToFormals() || funcInfo->GetIsStrictMode());
```
"HasAnyWriteToFormals" set by "Parser::BindPidRefsInScope" returns true in the following example code where "x" is formal. But the method can't detect the above buggy case, so it may end up wrongly optimizing arguments.
```
function f(x) {
x = 1;
}
```
暂无评论