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

[Tristan Seligmann]

On Mon, Feb 11, 2013 at 6:47 PM, Johan Holmquist <holmisen at gmail.com> wrote:
> By "agressive optimisation" I mean an optimisation that drastically
> reduces run-time performance of (some part of) the program. So I guess
> automatic vectorisation could fall into this term.

Even something like running the program on a different CPU or
different OS version can "drastically" improve or harm the performance
of a particular program, without any change in the compiler itself. If
you care about performance, the only real recourse is to have
benchmarks / performance tests that verify the things you care about,
and run them regularly in your target environment so that any
performance-critical changes are noticed right away.
-- 
mithrandi, i Ainil en-Balandor, a faer Ambar