GhcLibHcOpts: -O or -O2?

Joachim Breitner mail at
Tue Jul 15 22:09:13 UTC 2014


I found that some performance tests cases fail in some setting, and not
in another, and after a while I found the cause: 
The default settings (i.e. no mk/ have GhcLibHcOpts=-O2, while
most development profiles (e.g. devel2) _and the validate settings_ have

It doesn’t make a lot of sense to have performance tests cases without
fixing this parameter. And I think we really should be validating the
settings that we actually used in the final build that we release.

Hence three questions:

 1. Are the default settings really the settings used when producing the
    final build?
 2. Do we want to use GhcLibHcOpts=-O2 or GhcLibHcOpts=-O for releases?
 3. Once 2. is answered, may I change the validate settings to that 
    value, and update the performance tests to expect the number
    produced with that value?

(This was first observed in but I wanted to
the wider audience of the mailing list for such a design decision.)

Joachim Breitner
  e-Mail: mail at
  Jabber-ID: nomeata at

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