On Thu, 8 Aug 2024 17:20:06 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. >> >> >> . SATURATING_UADD : Saturating unsigned addition. >> . SATURATING_ADD : Saturating signed addition. >> . SATURATING_USUB : Saturating unsigned subtraction. >> . SATURATING_SUB : 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 with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains three additional > commits since the last revision: > > - Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8338201 > - Removed redundant comment > - 8338021: Support saturating vector operators in VectorAPI src/hotspot/share/opto/type.cpp line 495: > 493: TypeInt::POS1 = TypeInt::make(1,max_jint, WidenMin); // Positive > values > 494: TypeInt::INT = TypeInt::make(min_jint,max_jint, WidenMax); // > 32-bit integers > 495: TypeInt::UINT = TypeInt::make(0, max_juint, WidenMin); // Unsigned > ints This would make an illegal type, right? Since `TypeInt` is signed using `max_juint` as the hi value would end up as signed -1, resulting in the type `0..-1`, an empty type. I wonder if there's a better way to handle this, since in the type system empty types are in a sense equivalent to `TOP`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/20507#discussion_r1710642379
