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

[David Holmes]

On Fri, 28 Jul 2023 21:27:39 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> src/hotspot/share/classfile/stackMapTableFormat.hpp line 481:
>> 
>>> 479: 
>>> 480:   static u1 chops_to_frame_type(int chop) {
>>> 481:     return (u1)(251 - chop);
>> 
>> This looks dangerous. If the range is alway within `u1`, it should use `checked_cast<u1>`, and you should also assert `chop <= 251`.
>
> I agree, this one I should have used checked_cast and test the range of chop.

I also wondered about the range check but then I looked at the caller. No need to check it it in both places.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15056#discussion_r1278291467