Messages in this thread | | | Date | Wed, 28 Dec 2005 13:02:24 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers |
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On Wed, 28 Dec 2005, Arjan van de Ven wrote: > > yup that's why the patch only does it for gcc4, in which the inlining > heuristics finally got rewritten to something that seems to resemble > sanity...
Is that actually true of all gcc4 versions? I seem to remember gcc-4.0 being a real stinker.
> > Also, the inlining patch apparently makes code larger in some cases, > > so it's not even a unconditional win. > > .... as long as you give the inlining algorithm enough information. > -fno-unit-at-a-time prevents gcc from having the information, and the > decisions it makes are then less optimal... > > (unit-at-a-time allows gcc to look at the entire .c file, eg things like > number of callers etc etc, disabling that tells gcc to do the .c file as > single pass top-to-bottom only)
I'd still prefer to see numbers with -funit-at-a-time only. I think it's an independent knob, and I'd be much less worried about that, because we do know that unit-at-a-time has been enabled on x86-64 for a long time ("forever"). So that's less of a change, I feel.
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