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-fmove-all-movables and -freduce-all-givs
- From: Mark Stephenson <mstephen at MIT dot EDU>
- To: gcc at gcc dot gnu dot org, fortran at gnu dot org
- Date: Mon, 26 Apr 2004 17:10:57 -0400
- Subject: -fmove-all-movables and -freduce-all-givs
Sorry to bother you,
I'm currently researching how machine learning algorithms can be
employed to discover effective compiler heuristics. I see from your
online documentation that -fmove-all-movables and -freduce-all-givs can
sometimes generate slower code.
These optimizations seem like prime candidates for machine learning
because the tradeoffs are not clear (in my mind it seems like the
optimizations should always yield speedups).
Can you please let me know for which applications these optimizations
are detrimental to performance? And do you have any intuition as to why
they are detrimental?
Thanks a lot,
Mark Stephenson
p.s. - I've been using the Open Research Compiler to perform my
research, but I am now looking to switch over to gcc and g77.