RFR: 8250745: Fix a potential bug on AVX512 machines with assert(eval_map.contains(n)) failed: absent

[jiefu(傅杰)]

Thanks Vladimir Ivanov and Vladimir Kozlov for your review.

Will push it several hours later (since the hotspot code review must be there for at least 24 hours).

Best regards,
Jie

On 2020/7/30, 4:07 AM, "Vladimir Ivanov" <vladimir.x.ivanov at oracle.com> wrote:

    FYI test results are clean (hs-precheckin-comp,hs-tier1,hs-tier2).
    
    Best regards,
    Vladimir Ivanov
    
    On 29.07.2020 12:20, Vladimir Ivanov wrote:
    >> Webrev: http://cr.openjdk.java.net/~jiefu/8250745/webrev.00/
    > 
    > Looks good.
    > 
    > FTR the bug was introduced by JDK-8241040, but I don't see a way it can 
    > be hit by auto-vectorizer: before it kicks in, scalar code is strongly 
    > normalized and constants are pushed to the right. It leads to the shape 
    > where (Replicate -1) is always the second input of bitwise NOT shape 
    > (XorV v (Replicate -1)). Since there are no GVN transformations 
    > happening for vector nodes, both left-hand and right-hand variants 
    > become possible with Vector API.
    > 
    > Best regards,
    > Vladimir Ivanov