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Date: Fri, 6 Feb 2004 03:19:46 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Ruslan Ermilov <ru@FreeBSD.org>
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cc: current@FreeBSD.org
Subject: Re: Very long SRCS list with unusually long src/ prefix
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On Thu, 5 Feb 2004, Ruslan Ermilov wrote:

> On Fri, Feb 06, 2004 at 01:40:45AM +1100, Bruce Evans wrote:
> > On Thu, 5 Feb 2004, Ruslan Ermilov wrote:
> [...]
> > % +.for f in ${DPSRCS:M*.[cS]} ${DPSRCS:M*.cc} ${DPSRCS:M*.C} ${DPSRCS:M*.cpp} \
> > % +    ${DPSRCS:M*.cxx} ${DPSRCS:M*.m}
> > % +_mkdep_${f}: ${f}
> > % +	@echo ${.ALLSRC}
> > % +.endfor
> >
> > This seems to run echo once for each file separately.  It should be deemed
> > inefficient :-).
> >
> But that's what this patch basically does: it splits possibly very
> long ${.ALLSRC} list into pieces.  It's very inefficient only in
> traditional mode.  Run this with and without -j1 to see the diff:
>
> : COUNT!=	jot 1000
> :
> : all:
> : .for foo in ${COUNT}
> : 	@echo $$$$ >/dev/null
> : .endfor

That is slow too.  I get 12.12 seconds with make, 2.36 with make -j1,
1.37 with a shell loop and bash-1, 1.35 with a shell loop and /bin/sh,
and 0.0042 with jot 1000 >/dev/null.

I wonder about all those little dependencies too.  make already takes
a noticeable amount of time to handle large subdirs (here it takes 0.48
seconds for a null "make depend").

> > %  ${DEPENDFILE}: ${DPSRCS}
> > %  	rm -f ${DEPENDFILE}
> > %  .if !empty(DPSRCS:M*.[cS])
> > % -	${MKDEPCMD} -f ${DEPENDFILE} -a ${MKDEP} \
> > % -	    ${CFLAGS:M-nostdinc*} ${CFLAGS:M-[BID]*} \
> > % -	    ${.ALLSRC:M*.[cS]}
> > % +	(cd ${.CURDIR}; ${MAKE} _mkdep_cS) | xargs env \
> > % +	    ${MKDEPCMD} -f ${DEPENDFILE} -a ${MKDEP} \
> > % +	    ${CFLAGS:M-nostdinc*} ${CFLAGS:M-[BID]*}
> >
> > make uses a real shell, so the env shouldn't be needed.
> >
> $ echo foo.c | xargs CC=cc mkdep
> xargs: CC=cc: No such file or directory

$ echo foo.c | CC=cc xargs mkdep

Bruce