On 10 August 2006 06:32, Peter Tanski wrote:
> for the Makefile in ghc/rts, in lines 300-346,
> GC_HC_OPTS += -optc-O3
> --isn't this problematic? gcc, from -O2 on includes
-fgcse which
> may *reduce* runtime performance in programs using
computed
> gotos; -fgcse is actually run twice, because
> -frerun-cse-after-loop is also set at -O2. Would it
be better to
> pass individual flags, such as -funroll-loops and
> -falign-loops=16 (ppc, Intel setting)?
Possibly, yes. IIRC, -O3 was mainly to get some loop unrolling. This
is a performance-critical part of the system though, and when making any
changes we like to measure things to make sure we haven't pessimised
performance.
> (3) I have been looking at how to implement a dual-constructor-in-a-
> pointer for Integer (i.e., merge constructors of small Integers and
> big Integers into the Int#). Would that solution be workable or
> might it break current Haskell programs? Just a thought.
Which representation in particular are you talking about here?
Cheers,
Simon
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