On Sun, Dec 25, 2011 at 6:02 PM, Miles Bader <[email protected]> wrote: > 2011/12/26 Olaf van der Spek <[email protected]>: >> On Sun, Dec 25, 2011 at 5:31 PM, Miles Bader <[email protected]> wrote: >>> 2011/12/26 Olaf van der Spek <[email protected]>: >>>>> Faster enough to be worth the annoyance for the developer of twisting >>>>> his source code to fit the "pch style" (which seems notably uglier)? >>>> >>>> Yes >>>> I'm not sure what twisting you're referring too though. >>> >>> Another comment noted that PCH was often ineffective or even >>> counter-productive unless the bulk of your includes are precisely the >>> same between compilation units, and that in practice systems like VS >>> try to get the user to define a single "include everything" header >>> file (presumably instead of the normal practice of "include the stuff >>> you use"). >>> >>> Sounds pretty darn ugly (and I expect makes compile times far worse if >>> you _can't_ use PCH in some case)... >> >> Is someone forcing you to use PCH? I'm not sure what your point is. > > Er, of course not (where on earth did that come from)?
I didn't get your point and it seemed you were repeating unfounded arguments. > My initial question was essentially "is PCH still a good idea for the > average developer?" > > That basically involves examining the details of the tradeoff between > benefits (increased compile speed; how much?) and drawbacks (awkward > constraints on source style / organization; exactly what is needed to > make PCH effective?). I measured speedup of 70% without -O3 and 50% with -O3 on one of my projects when build with g++. The project is primarily developed on MSVC so it already had a stdafx.h (pch header). I don't find the common header awkward at all, I'd rather not repeat lots of the common includes in lots of source files. > This is relevant to automake because the general utility of > specialized PCH support in automake has to be weighed against the cost > of that support (of course, maybe it's super trivial, I dunno). Right. I think the cost is low, since the concept is so simple. Olaf
