[squeak-dev] The Trunk: System-dtl.685.mcz

Eliot Miranda eliot.miranda at gmail.com
Mon Sep 8 18:45:47 UTC 2014


On Sun, Sep 7, 2014 at 1:58 PM, <commits at source.squeak.org> wrote:

> David T. Lewis uploaded a new version of System to project The Trunk:
> http://source.squeak.org/trunk/System-dtl.685.mcz
>
> ==================== Summary ====================
>
> Name: System-dtl.685
> Author: dtl
> Time: 7 September 2014, 4:58:15.377 pm
> UUID: 55eba121-23d3-41cc-9525-52554adac2ec
> Ancestors: System-eem.684
>
> Smalltalk isRunningCog should answer false for an interpreter VM
>
> =============== Diff against System-eem.684 ===============
>
> Item was changed:
>   ----- Method: SmalltalkImage>>isRunningCog (in category 'system
> attributes') -----
>   isRunningCog
>         "Answers if we're running on a Cog VM (JIT or StackInterpreter)"
>
> +       ^( [self vmParameterAt: 42] on: Error do: [] )
> -       ^(self vmParameterAt: 42)
>                 ifNil: [false]
>                 ifNotNil: [:numStackPages| numStackPages > 0]!
>

Instead of creating an exception handler why not modify the interpreter to
answer nil?  I know the answer is that the Interpreter doesn't, and fails.
 But we've had years in which we could change the Interpreter to match
vmParameterAt: and instead of doing the good thing (have the Interpreter
answer nil for values answered by Cog VMs), we force the standard system to
waste time.  We should optimize the common case (trunk running on Cog) not
penalize it to cover the uncommon case (trunk running on Interpreter VM).
-- 
best,
Eliot
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