RFR: 8293329: x86: Improve handling of constants in AES/GHASH stubs

[Vladimir Kozlov]

On Fri, 2 Sep 2022 23:24:32 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Pre-generating constants saves on startup and static/dynamic footprint a bit, plus simplifies bootstrapping logic. 
> 
> As a downside, constants aren't guaranteed to be always reachable anymore, but since they are used from stubs, finding a scratch register when needed is not a problem.
> 
> Testing: 
> - [x] hs-tier1 - hs-tier4 w/ `-XX:+ForceUnreachable` 
> - [x] x86_32 build

I would like to see the effect on performance. In worst case constants will not be reachable always. Changes are fine if the effect is negligible.

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PR: https://git.openjdk.org/jdk/pull/10152