On Mon, 31 Oct 2022 02:15:35 GMT, Quan Anh Mai <qa...@openjdk.org> 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