[Vm-dev] [commit][3753] Do not use -O3 optimization, -O2 is safer and works well.

[Ben Coman]

On Wed, Dec 21, 2016 at 9:03 AM,  <commits at squeakvm.org> wrote:
>
> Revision: 3753
> Author:   lewis
> Date:     2016-12-20 17:03:04 -0800 (Tue, 20 Dec 2016)
> Log Message:
> -----------
> Do not use -O3 optimization, -O2 is safer and works well.
>
> gcc 4.9.2 gives crashes and heisenbugs with OSPP compiled with -O3.
>
> Symptoms:
> (1 to: 10) collect: [ :e | (CommandShell new pipeline: 'ps > /dev/null | cat') output]
>   ==> segfaults in some of the spawned child processes
>
> This appears to be an actual compiler bug, although it goes away when print
> statements are added, so I cannot say for sure (and it is difficult to attach
> gdb to the newly spawned child process before it crashes). The bad behavior
> happens only with -O3 and there are no real performance benefits compared
> to -O2 (bytecodes faster, sends slower).

I'd be interested to know the reason sends get slower (if known).
cheers -ben