RFR: 8311847: Fix -Wconversion for assembler.hpp emit_int8,16 callers

[Dean Long]

On Tue, 11 Jul 2023 02:54:13 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Please review changes to fix -Wconversion warnings that come from assembler_<cpu>.cpp by adding narrow_casts to the emit_int8,16,24, and 32 functions.  And some other fixups with checked_cast.
>> 
>> Ran tier1 on Oracle platforms, and tier1-4 on linux-x64-debug, linux-aarch64-debug, windows-x64-debug.
>
> src/hotspot/share/asm/assembler.hpp line 305:
> 
>> 303: 
>> 304: 
>> 305:  public:
> 
> I don't think we need this.  See below.

Nevermind, I tried my alternative idea below and it didn't work.  For these particular cases where we only care about going to uint8_t, we could check is8bit().  Another trick I've seen is checking if (val >> width) is 0 or -1.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/14822#discussion_r1259328766