RFR: 8324123: aarch64: fix prfm literal encoding in assembler [v4]

[Wang Zhuo]

On Wed, 24 Jan 2024 08:42:34 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Wang Zhuo has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   get some comments back
>
> src/hotspot/cpu/aarch64/assembler_aarch64.cpp line 192:
> 
>> 190: // This encoding is similar (but not quite identical) to the encoding used
>> 191: // by literal ld/st. see JDK-8324123.
>> 192: // FIXME: PRFM should not be used with writeback modes, but the assembler
> 
> FIXME: is it ok to leave this in the code?
> I think we prefer filed RFE's to comments in the code that nobody will ever look at again.
> You can put the RFE number in the code though.

Thanks. The FIXME was there because PRFM did not support pre/post indexing and we had no check for that. 
Some guarantee checks were added and FIXME was removed.
Please check the last 3 patches.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17482#discussion_r1466260270