notes from Valhalla meeting 5/24/17

[John Rose]

We have talked about "condy" (a constant-pool friend for indy).
Enclosed is the javadoc portion of a draft spec.
The JVM spec. is not ready and will be sent separately.
This javadoc reflects code checked into the condy branch of Amber.

On Jun 5, 2017, at 4:21 PM, Karen Kinnear <karen.kinnear at oracle.com> wrote:
> From: Karen Kinnear <karen.kinnear at oracle.com>
> Subject: notes from Valhalla meeting 5/24/17
> Date: June 5, 2017 at 4:21:59 PM PDT
> To: valhalla-spec-experts at openjdk.java.net

> …
> Condy (ConstantDynamic) update: John & Brian
>   goal  1. raising BootstrapMethod static argument limit to s to the 64-1 (from 251)
>      variable arity - package as an array which is unlimited
>      if short arg list: invoke, if long, invoke with args
>      both behaviors aligned, so specification doesn't have to specify line between short and long
>      javadoc almost ready
>   Dan H: note: java language today limits to 251
> 
>   goal  2. support lazy resolution - resolve in BSM
>      new BSM mode: allows catching exceptions from subsidiary constant resolution
>      today we push arguments, proposing pushing the number of arguments, so the BSM can pull the arguments lazily
>      Expose a way for the BSM to get the arguments
>   Dan H: is this a BSM attribute index or a CP index?
>   Karen: we hope this is a BSM attribute index - to reduce constraints on the runtime implementation
>   Dan H:   Need to work out requirements across redefinitions
>     John: not specify if return old or new values
>   Dan H: useful for expression trees in constant pool - mostly constant except for 1 or 2 parameters
> 
>   goal 3. Allow writing BSM more like writing ordinary methods
> 
> John: Also want groups of constants to not consume CP indices


http://cr.openjdk.java.net/~jrose/jvm/specdiff-condy-2017-0609.zip