On Thu, 24 Apr 2025 23:29:28 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!
>
> Vladimir Ivanov has updated the pull request incrementally with one
> additional commit since the last revision:
>
> Improve comments
src/hotspot/cpu/riscv/riscv.ad line 1947:
> 1945: // Vector calling convention not yet implemented.
> 1946: bool Matcher::supports_vector_calling_convention(void) {
> 1947: return EnableVectorSupport;
You might want to remove the use of `UseVectorStubs` in
`Matcher::vector_return_value` at L1951.
assert(EnableVectorSupport && UseVectorStubs, "sanity");
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PR Review Comment: https://git.openjdk.org/jdk/pull/24462#discussion_r2059390324
