optimization issue about -O2 and -Os

[Dave Korn]

> -----Original Message-----
> From: Zack Weinberg 
> Sent: 30 April 2004 18:00

> "Dave Korn" <> writes:
> 
> >
> >   Ah, I stand corrected.  Would it be accurate to say that 
> they are _both_
> > shorthand for a set of -f options _and_ _also_ control a 
> set of other
> > behaviours, which entail enabling, disabling, or 
> fine-tuning the parameters
> > of other optimisations that do not correspond directly to 
> -f options ?
> 
> Yeah, that's pretty accurate.  You can look through the source code
> for instances of the global flags "optimize" and "optimize_size".
> Anything you can do to improve the documentation in this regard would
> be much appreciated.  It would probably be a good move to deemphasize
> all those -f switches; they tend not to be all that useful; I consider
> their primary purpose to be working around bugs in specific
> optimizations, using -On -fno-<buggy-pass>.
> 
> zw


  Hmm, maybe it would be worthwhile to invent -f options for all these
ad-hoc tests on the optimize variables, so that the -O options then *did*
become shorthand for flag sets, and the suggestion I already made for
localising the failure with a given -O setting would actually work?


    cheers, 
      DaveK
-- 
Can't think of a witty .sigline today....