Regexes match from left to right. So, if you first say "match /*", and then say, "don't match throw", it's *not* going to exclude "/*"'s that are preceeded with "throw". In fact, you haven't given any requirements for what should preceed "/*".

Ignoring the fact that you don't specify what should happen on a line like this:

    /* throw /*
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you might want to use something like:

    m!^(?:(?!throw).)*/[*]!s
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although that can probably be optimized (and the more you know about where you are going to match against, the more possibilities for optimizing there are).

Abigail