RFR: 8215159: Improve initial setup of system Properties

[Mandy Chung]

On 12/11/18 10:08 AM, Roger Riggs wrote:
>
> VM.java:
>  - line 180:  The savedProps doesn't need to be (and was not 
> previously) unmodifiable.
>    Seems safer this way though since the map at the bottom is not 
> ConcurrentHashMap.
>    Its not entirely clear who calls getSavedProperties().
>    Would it be more efficient for savedProps to be the unmodifiable 
> map and not create
>    one on every call to getSavedProperties.
>

JVMCI and Graal depends on VM::getSavedProperties to determine if JVMCI 
is enabled
and also to get other Graal-specific system properties set at startup.

VM::getSavedProperties is not called in the common case and creating a 
unmodifiable map
when getSavedProperties is called is reasonable.


Mandy