RFR: 8328998: Encoding support for Intel APX extended general-purpose registers [v4]

[Steve Dohrmann]

On Fri, 26 Apr 2024 17:37:05 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Steve Dohrmann has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   bug fix in other ::prefix_rex2
>
> src/hotspot/cpu/x86/assembler_x86.cpp line 13260:
> 
>> 13258:   } else {
>> 13259:     emit_int24((prefix & 0xFF00) >> 8, prefix & 0x00FF, b1);
>> 13260:   }
> 
> We need a check for UseAPX > 0 here.

Thank you.  Added check.

> src/hotspot/cpu/x86/assembler_x86.cpp line 14004:
> 
>> 14002:   int encode = prefixq_and_encode(dst->encoding(), src->encoding(), true);
>> 14003:   emit_opcode_prefix_and_encoding((unsigned char)0xB8, 0xC0, encode);
>> 14004: }
> 
> void Assembler::popcntq(Register dst, Address src) also need to be handled for rex2 generation. get_prefixq() will return a 16 bit entity and so call to emit_int32 directly is not correct.
>  emit_int32((unsigned char)0xF3,
>              get_prefixq(src, dst),
>              0x0F,
>              (unsigned char)0xB8);
> 
> Likewise void Assembler::cvttsd2siq(Register dst, Address src) also needs to be updated to handle extended gprs.

Thank you, missed these.  Updated popcntq(Register dst, Address src) and cvttsd2siq(Register dst, Address src) for egpr support.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/18476#discussion_r1583824704
PR Review Comment: https://git.openjdk.org/jdk/pull/18476#discussion_r1583824212