RFR: 8345047: RISC-V: Remove explicit use of AvoidUnalignedAccesses in interpreter

[Fei Yang]

On Tue, 26 Nov 2024 10:57:30 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> src/hotspot/cpu/riscv/interp_masm_riscv.cpp line 182:
>> 
>>> 180: void InterpreterMacroAssembler::get_unsigned_2_byte_index_at_bcp(Register reg, int bcp_offset) {
>>> 181:   assert(bcp_offset >= 0, "bcp is still pointing to start of bytecode");
>>> 182:   lbu(t1, Address(xbcp, bcp_offset));
>> 
>> maybe we could expand the revb_h_h here? something like below:
>> 
>> if ((AvoidUnalignedAccesses && (bcp_offset % 2)) || !UseZbb) {
>>   ...
>> } else {
>>   // expand revb_h_h_u when +UseZbb
>> }
>
> similar comments for below changes.

Ah, that looks more complex than before from a maintainance perspective. We only get one instruction saved which is not on the performance critical path. I guess it doesn't worth it?

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PR Review Comment: https://git.openjdk.org/jdk/pull/22387#discussion_r1858277897