RFR: 8313249: Fix -Wconversion warnings in verifier code [v2]

[David Holmes]

On Fri, 28 Jul 2023 23:14:33 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> This one clearly is < u1 since it checks the value for appends.
>
> I would use static_cast to be consistent with `chops_to_frame_type`. That way the reader of this code has less metal exercise to do.

I've struggled with the raw cast versus checked_cast usage in this PR - I could not determine what was guiding the usage of each type of cast. Shouldn't it always be a checked cast? Or does the preceding range check validate the use of a raw cast (so we don't range check twice)?

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PR Review Comment: https://git.openjdk.org/jdk/pull/15056#discussion_r1278291644