RFR(M) JDK-8031819: Remove legacy jdk checks and code

[David Holmes]

On 6/06/2014 11:07 PM, Daniel D. Daugherty wrote:
> On 6/5/14 11:26 PM, David Holmes wrote:
>
>  > But everyone needs to be very aware that once this goes in you
>  > can forget about placing a JDK 9 VM anywhere but a JDK 9 JDK.
>  > (Or did we already hit that?)
>
> This caught my eye... Have we already reached a point where we
> can't put the current JDK9 JVM into various JDK8 builds? I know
> we have restrictions about putting the current JVM (and the
> HSX-25 JVM) into JDK7...

I think I over generalized. We can no longer drop it into any JDK for 
which we previously had special code guarded with a version check. That 
would generally mean 7+ is okay _but_ we already made changes that make 
the VM incompatible with 7 (long ago) so that leaves 8+. We just have to 
watch for semantic changes in 9 versus 8.

David
-----

> If the current JDK9 JVM (prior to this changeset) can still be
> dropped into JDK8 and this changeset makes it so that the JDK9
> JVM can no longer be dropped into JDK8, then we need to get
> wider feedback than hotspot-runtime-dev at ...
>
> In particular, the HotSpot Compiler and Performance teams should
> be notified since dropping the current JVM into an older JDK is
> one of their standard failure analysis techniques; don't know
> if the HotSpot GC team does that trick much.
>
> Dan