On Mon, 19 Aug 2024 07:19:30 GMT, Jatin Bhateja <jbhat...@openjdk.org> wrote:
>> Hi All, >> >> As per the discussion on panama-dev mailing list[1], patch adds the support >> following new vector operators. >> >> >> . SUADD : Saturating unsigned addition. >> . SADD : Saturating signed addition. >> . SUSUB : Saturating unsigned subtraction. >> . SSUB : Saturating signed subtraction. >> . UMAX : Unsigned max >> . UMIN : Unsigned min. >> >> >> New vector operators are applicable to only integral types since their >> values wraparound in over/underflowing scenarios after setting appropriate >> status flags. For floating point types, as per IEEE 754 specs there are >> multiple schemes to handler underflow, one of them is gradual underflow >> which transitions the value to subnormal range. Similarly, overflow >> implicitly saturates the floating-point value to an Infinite value. >> >> As the name suggests, these are saturating operations, i.e. the result of >> the computation is strictly capped by lower and upper bounds of the result >> type and is not wrapped around in underflowing or overflowing scenarios. >> >> Summary of changes: >> - Java side implementation of new vector operators. >> - Add new scalar saturating APIs for each of the above saturating vector >> operator in corresponding primitive box classes, fallback implementation of >> vector operators is based over it. >> - C2 compiler IR and inline expander changes. >> - Optimized x86 backend implementation for new vector operators and their >> predicated counterparts. >> - Extends existing VectorAPI Jtreg test suite to cover new operations. >> >> Kindly review and share your feedback. >> >> Best Regards, >> PS: Intrinsification and auto-vectorization of new core-lib API will be >> addressed separately in a follow-up patch. >> >> [1] https://mail.openjdk.org/pipermail/panama-dev/2024-May/020408.html > > Jatin Bhateja has updated the pull request incrementally with one additional > commit since the last revision: > > Review comments resolutions. src/hotspot/cpu/x86/x86.ad line 1773: > 1771: return false; > 1772: } > 1773: if (bt == T_LONG && !VM_Version::supports_avx512vl()) { we should be able to support bt == T_LONG for 512 bit irrespective of avx512vl. src/hotspot/cpu/x86/x86.ad line 1953: > 1951: if (UseAVX < 1 || size_in_bits < 128 || (size_in_bits == 512 && > !VM_Version::supports_avx512bw())) { > 1952: return false; > 1953: } UseAVX < 1 could be written as UseAVX == 0. Could we not do register version for size_in_bit < 128? src/hotspot/cpu/x86/x86.ad line 1962: > 1960: return false; // Implementation limitation > 1961: } > 1962: break; Could we not do register version for size_in_bit < 128? src/hotspot/cpu/x86/x86.ad line 2143: > 2141: if (is_subword_type(bt) && !VM_Version::supports_avx512bw()) { > 2142: return false; // Implementation limitation > 2143: } UMinV and UMaxV are supported on AVX1, AVX2 platform. src/hotspot/cpu/x86/x86.ad line 2155: > 2153: return false; // Implementation limitation > 2154: } > 2155: return true; Byte/Short saturating vector add is supported for AVX1, AVX2 platforms. Could we not do register version for size_in_bit < 128? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/20507#discussion_r1733330892 PR Review Comment: https://git.openjdk.org/jdk/pull/20507#discussion_r1733333203 PR Review Comment: https://git.openjdk.org/jdk/pull/20507#discussion_r1733333608 PR Review Comment: https://git.openjdk.org/jdk/pull/20507#discussion_r1733336005 PR Review Comment: https://git.openjdk.org/jdk/pull/20507#discussion_r1733338300
