RFR: 8300253: Introduce AArch64 nzcv accessors [v2]

[Erik Österlund]

On Fri, 20 Jan 2023 02:06:29 GMT, Hao Sun <haosun at openjdk.org> wrote:

>> Erik Österlund has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add test
>
> test/hotspot/gtest/aarch64/aarch64-asmtest.py line 1462:
> 
>> 1460: for system_reg in ["fpsr", "dczid_el0", "ctr_el0", "nzcv"]:
>> 1461:     generate (SystemOneRegOp, [ ["msr", system_reg] ])
>> 1462:     generate (OneRegSystemOp, [ ["mrs", system_reg] ])
> 
> Suggestion:
> 
> for system_reg in ["fpsr", "nzcv"]:
>     generate (SystemOneRegOp, [ ["msr", system_reg] ])
>  
> for system_reg in ["fpsr", "dczid_el0", "ctr_el0", "nzcv"]:
>     generate (OneRegSystemOp, [ ["mrs", system_reg] ])
> 
> 
> 1. `asmtest.out.h` should be updated as well. Note that it's generated by running `aarch64-asmtest.py` script.
> 2. There are no instructions to "set/update" `dczid_el0` or `ctr_el0` in `macroAssembler_aarch64.hpp`. Here shows the warnings of running `python2 aarch64-asmtest.py`:
> 
> aarch64ops.s: Assembler messages:
> aarch64ops.s:202: Warning: specified register cannot be written to at operand 1 -- `msr dczid_el0,x27'
> aarch64ops.s:206: Warning: specified register cannot be written to at operand 1 -- `msr ctr_el0,x11'

Oops. I fixed the test and added the generated code as suggested.

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PR: https://git.openjdk.org/jdk/pull/12038