RFR: 8309685: Fix -Wconversion warnings in assembler and register code [v8]

[Coleen Phillimore]

On Tue, 20 Jun 2023 12:53:58 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This change widens some int arguments, narrows some int returns and adds some casts and checked_casts where the compiler was doing the implicit conversion.  I maintained existing types - ie if the parameter was short, I used a cast to short.  Also int is used in places that might be better served as unsigned int but I didn't fix that because it would be too large and risky.  The registers encode an offset in an array, so it's safe to checked_cast<> to get their encoding. This fix is limited so that the types changed and casts added are intentional.
>> See CR for counts of -Wconversion warnings this resolves.
>> Tested with tier1-7, also tested with tier1 on all Oracle supported platforms.
>
> Coleen Phillimore has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
> 
>  - Merge branch 'master' into more-conversion
>  - Merge branch 'master' into more-conversion
>  - Isolate the -1 cast case to assembler.hpp since those are the callers.
>  - Another attempt at casting assembler.hpp emit functions.
>  - First fix math.
>  - Happy to add riscv, thanks.
>  - Improve checked_cast to tolerate sign extension so it can be used in assembler.hpp emit code.
>  - 8309685: Fix -Wconversion warnings in assembler and register code

I'm going to break this up more.

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PR Comment: https://git.openjdk.org/jdk/pull/14396#issuecomment-1599198952