RFR: 8255210: [Vector API] jdk/incubator/vector/Int256VectorTests.java crashes on AVX512 machines

[Vladimir Ivanov]

On Thu, 22 Oct 2020 03:12:31 GMT, Jie Fu <jiefu at openjdk.org> wrote:

> Hi all,
> 
> Please review the fix of an AVX512 crash for Vector API.
> The reason is that reductionI in x86.ad didn't use legVec for code generation, which is required by Assembler::vphaddd.
> 
> Testing:
>  - test/jdk/jdk/incubator/vector all passed on both AVX256 and AVX512 machines
> 
> Thanks.
> Best regards,
> Jie

src/hotspot/cpu/x86/x86.ad line 4429:

> 4427: instruct reductionI(rRegI dst, rRegI src1, legVec src2, legVec vtmp1, legVec vtmp2) %{
> 4428:   predicate(vector_element_basic_type(n->in(2)) == T_INT &&
> 4429:             vector_length(n->in(2)) <= 16); // src2

FTR since `reduction16I` is gone, vector length check becomes redundant: `reductionI` successfully covers the whole range of vectors of int.

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PR: https://git.openjdk.java.net/jdk/pull/791