RFR: 8354473: Incorrect results for compress/expand tests with -XX:+EnableX86ECoreOpts

[Emanuel Peter]

On Tue, 15 Apr 2025 03:54:09 GMT, Volodymyr Paprotski <vpaprotski at openjdk.org> wrote:

> It looks like the `permv` mask isnt always 'all-ones' or 'all-zeroes'. (Which is OK for real blend, but needs to be enforced via the flag for blend emulation)
> 
> Before the fix, `make test TEST="jdk/incubator/vector"` (on ECore machine)
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP
>>> jtreg:test/jdk/jdk/incubator/vector                  83    71    10     0     2 <<
> ==============================
> TEST FAILURE
> 
> After the fix:
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP
>    jtreg:test/jdk/jdk/incubator/vector                  83    81     0     0     2
> ==============================
> TEST SUCCESS
> 
> And on an AVX512 machine:
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP
>    jtreg:test/jdk/jdk/incubator/vector                  83    81     0     0     2
> ==============================
> TEST SUCCESS

Looks reasonable to me. I did run our testing, so it won't break out CI. But I think we are not yet running our testing with `-XX:+EnableX86ECoreOpts`, so no guarantees there ;)

-------------

Marked as reviewed by epeter (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24645#pullrequestreview-2816950724