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Re: gcc compile-time performance


On Sat, May 18, 2002 at 03:11:49AM -0300, Alexandre Oliva wrote:
> On May 17, 2002, "Chip Cuntz" <chip.cuntz@earthling.net> wrote:
> 
> >> It's also interesting to note how the compiler tree keeps taking
> >> longer to compile.
> 
> > On the dog of an AIX box I have it takes two days to bootstrap gcc!
> 
> Well, mine takes about the whole week to bootstrap and test it.
> 
> 
> I wonder how much of a performance win we'd observe by replacing every
> occurrence of:
> 
>   if (some_condition)
>     abort ();
> 
> with
> 
>   if (flag_internal_checks && some_condition)
>     abort ();
> 
> 
> I've certainly contributed myself to slow downs in the compiler, by
> introducing sanity checks in a number of functions called quite often.

Or how much of a win we could get from using __builtin_expect in sanity
checks... do we actually assume checks leading to a noreturn function
call are unlikely, yet, or is that only on the CFG branch?

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer


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