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Re: gcc and compiling speed

Marc Espie <> writes:

>> What you don't realize, perhaps, is just how data-driven gcc (any
>> version) is.  I could spend weeks tuning gcc to work well on mozilla
>> and it could make no. difference. whatsoever. to how long it takes to
>> compile OpenBSD core.

Thank you.

> I'm just busy with various things, including an upcoming OpenBSD release,
> and a move between apartments, but I'll provide this preprocessed source
> as soon as it gets on the top list of my things to do.
> On the other hand, what you're saying is plain bullshit, Zack. The slowdown
> of gcc3 vs. gcc2 is NOT dependent on the set of source files.

You misunderstand.  I do not deny that gcc 3.3 is slower than gcc 2.95
for almost all C input (*please* be specific about minor version
numbers - 3.0, 3.[12], 3.3, 3.4, and mainline are all very different
beasts).  I have observed the slowdown myself, in fact.

What I said was that speeding up GCC for one set of source files is
unlikely to speed it up for another.  This is *also* true.  And this
is why we keep asking you for your test cases.

(If we get *enough* test cases, we can cover all the code paths and
speed the compiler up in general, but we aren't there yet.)


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