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

[Dean Long]

On Fri, 28 Jul 2023 22:13:08 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> See bugid for comments.  Most of the verifier code deals with ints, so the u2 and other parameters weren't really needed and can be promoted to int. Mostly types are changed, but a few checked_cast<>s are added.
>> Tested with tier1-4, sanity Oracle platforms.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Ioi's suggested changes.

With a little more fan-out (I tried it), it is possible to make _locals_size and _stack_size u2 instead of int32_t.  The old comment about using int32_t "to detect/recover from overflow or underflow conditions" seems a bit misguided considering how we are fixing -Wconversion warnings with narrower types and checked_cast(), and the related effort to remove signed overflow.

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PR Comment: https://git.openjdk.org/jdk/pull/15056#issuecomment-1656508718