Integrated: 8256073: Improve vector rematerialization support

[Vladimir Ivanov]

On Mon, 9 Nov 2020 21:46:00 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Having #1131, #1132, and #1134 in place, the only missing piece left to have vector rematerialization fully working is support of non-contiguous vector values in vector rematerialization logic. This patch covers that.
> 
> Current version makes the assumption that vector values are contiguously laid in memory. It's the case for on-stack locations, but for in-register values it's not the case (at least, on x86). Rewritten version doesn't make such assumption for in-register case anymore and processes every vector element independently.
> 
> (Along the way, the refactoring fixes a bug when handling a corner case: the case when a vector instance is scalarized by EA and the primitive array field (VectorPayload.payload) has a constant value (NULL) is erroneously treated as requiring custom rematerialization and it hits an assert.)
> 
> Testing (with other relevant patches):
> - [x] jdk/incubator/vector w/ -XX:+DeoptimizeALot and -XX:UseAVX={3,2,1,0} on AVX512-capable hardware
> - [x] hs-precheckin-comp, hs-tier1, hs-tier2

This pull request has now been integrated.

Changeset: 57025e65
Author:    Vladimir Ivanov <vlivanov at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/57025e65
Stats:     142 lines in 2 files changed: 38 ins; 69 del; 35 mod

8256073: Improve vector rematerialization support

Reviewed-by: thartmann, kvn

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PR: https://git.openjdk.java.net/jdk/pull/1136