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

[Ioi Lam]

On Sat, 29 Jul 2023 12:20:25 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> 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)?

To me, the two lines serves two purposes:


assert(appends > 0 && appends < 4, "Invalid append amount");

This is the input expected by this function.


    return static_cast<u1>(251 + appends);


This is a mechanical check that the code is actually correctly written (i.e., you didn't mess up and wrote (253 + appends). That way the reader doesn't have do the math in order to trust this code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15056#discussion_r1278370610