On Tue, 17 Oct 2023 09:09:52 GMT, Fei Yang <fy...@openjdk.org> wrote:
>> Ilya Gavrilin has updated the pull request incrementally with one additional >> commit since the last revision: >> >> Fix some registers usages and typos > > src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp line 1682: > >> 1680: // use floating-point 1.0 with a sign of input >> 1681: is_double ? fsgnj_d(dst, one, src) >> 1682: : fsgnj_s(dst, one, src); > > What if the `src` argument contains zero? Math.signum(float/double) is > supposed to return zero if the argument is zero [1]. > > [1] > https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/lang/Math.java#L2602 According to IEEE754, we can get positive or negative zero in the `src` register (also positive zero can be named as zero) , and these cases included to mask for the tmp1 (L1671-1676) and `src` value returned. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16186#discussion_r1361840030
