On Fri, 4 Apr 2025 22:52:24 GMT, Vladimir Ivanov <vliva...@openjdk.org> wrote:
> Migrate Vector API math library (SVML and SLEEF) linkage from native code (in
> JVM) to Java FFM API.
>
> Since FFM API doesn't support vector calling conventions yet, migration
> affects only symbol lookup for now. But it still enables significant
> simplifications on JVM side.
>
> The patch consists of the following parts:
> * on-demand symbol lookup in Java code replaces eager lookup from native
> code during JVM startup;
> * 2 new VM intrinsics for vector calls (support unary and binary shapes)
> (code separated from unary/binary vector operations);
> * new internal interface to query supported CPU ISA extensions
> (`jdk.incubator.vector.CPUFeatures`) used for CPU dispatching.
>
> `java.lang.foreign` API is used to perform symbol lookup in vector math
> library, then the address is cached and fed into corresponding JVM intrinsic,
> so C2 can turn it into a direct vector call in generated code.
>
> Once `java.lang.foreign` supports vectors & vector calling conventions, VM
> intrinsics can go away.
>
> Performance is on par with original implementation (tested with
> microbenchmarks on linux-x64 and macosx-aarch64).
>
> Testing: hs-tier1 - hs-tier6, microbenchmarks (on linux-x64 and
> macosx-aarch64)
>
> Thanks!
src/jdk.incubator.vector/share/classes/jdk/incubator/vector/CPUFeatures.java
line 44:
> 42: String featuresString = VectorSupport.getCPUFeatures();
> 43: debug(featuresString);
> 44: String[] features = featuresString.toLowerCase().split(", "); //
> ", " is used as a delimiter
Please use `toLowerCase(Locale.ROOT)`: if the system locale is turkish, `I` and
dotless i are two letters, and the dotless i will fail in the subsequent
`validateFeatures` assertion. Same for `hasFeature`.
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PR Review Comment: https://git.openjdk.org/jdk/pull/24462#discussion_r2031714743
