On Mon, 31 Oct 2022 02:15:35 GMT, Quan Anh Mai <[email protected]> wrote:
>> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 3387:
>>
>>> 3385: for (int idx = 0; idx < 4; idx++) {
>>> 3386: // h = (31 * h) or (h << 5 - h);
>>> 3387: movl(tmp, result);
>>
>> If you are unrolling this, maybe break the dependency chain, `h = h * 31**4
>> + x[i] * 31**3 + x[i + 1] * 31**2 + x[i + 2] * 31 + x[i + 3]`
>
> A 256-bit vector is only 8 ints so this loop seems redundant, maybe running
> with the stride of 2 instead, in which case the single scalar calculation
> does also not need a loop.
Working on this..
-------------
PR: https://git.openjdk.org/jdk/pull/10847
