RFR: 8330266: RISC-V: Restore frm to RoundingMode::rne after JNI [v2]

[Vladimir Kempik]

On Mon, 15 Apr 2024 16:25:14 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this patch?
>> As discussed at: https://github.com/openjdk/jdk/pull/18758#pullrequestreview-1999982333, we'd better to do it.
>> Similar thing is done on aarch64, https://bugs.openjdk.org/browse/JDK-8320892
>> 
>> Thanks
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   refine code

src/hotspot/cpu/riscv/macroAssembler_riscv.cpp line 1177:

> 1175:     // don't want non-IEEE rounding modes.
> 1176:     guarantee(RoundingMode::rne == 0, "must be");
> 1177:     beq(tmp, zr, skip_fsrmi);        // Only reset FRM if it's wrong

is it really better (performance wise) than doing it always, unconditionaly (so minus frrm, minus beq) ?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/18785#discussion_r1566395569