[Haskell-cafe] How far compilers are allowed to go with optimizations?

[Bardur Arantsson]

On 02/09/2013 09:56 AM, Johan Holmquist wrote:

[--snip--]
> It just so happened that the old code triggered some aggressive
> optimization unbeknownst to everyone, **including the original
> developer**, while the new code did not. (This optimization maybe even
> was triggered only on a certain version of the compiler, the one that
> happened to be in use at the time.)
> 
> I fear being P some day.
> 
> Maybe this is something that would never happen in practice, but how
> to be sure...
> 

It's definitely a valid point, but isn't that an argument *for* testing
for preformance regressions rather than *against* compiler optimizations?

Actually, it'd be really nice if you could have statically verifiable
big-O performance assertions in the code. I'm guessing that a lot of
work will have been done in this area. Anyone have any pointers to such
work?

Regards,