RFR: 8276215: Intrinsics matchers should handle native method flags better

[David Holmes]

On Mon, 1 Nov 2021 12:22:37 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Found this while working on JDK-8276096. It seems when the actual method is native, `F_R` (regular) intrinsic definition still matches. I believe that happens because flag matchers check for native flags only optionally. It would be better to implement this more consistently. This requires a few simple adjustments to current intrinsics definitions. #6184 handled a larger `StrictMath` oddity.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug `tier1`
>  - [x] Linux x86_64 fastdebug `tier2`
>  - [x] Linux x86_64 fastdebug `applications/ctw/modules` (which has a nice side-effect of touching a lot of JDK methods)

I find it very hard to evaluate this without understanding why ?native was used in the first place. It seems to indicate "could be native, don't care either way" and now we want a firm is_native or is_not_native. The implications of this are unclear to me. 

David

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PR: https://git.openjdk.java.net/jdk/pull/6187