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Re: [RFA]: simulator build failures with parallel make
On Sun, Apr 15, 2001 at 01:47:27PM -0700, J.T. Conklin wrote:
> >>>>> "HJ" == H J Lu <hjl@lucon.org> writes:
> >>>>> "Andrew" == Andrew Cagney <ac131313@cygnus.com> writes:
> Andrew> With that dependency added without -j does the generator get
> Andrew> run twice? I've this memory of a strange querk with make
> Andrew> dependencies and files being created as a sideeffect.
> >>
> >> No.
> >>
> >> But now that you've mentioned it, I recall that rules with multiple
> >> targets will be executed once per target with -j (at least with GNU
> >> make). This can be worked around by creating a psuedo-target to
>
> HJ> Please don't add any workaround. Just provide complete
> HJ> dependencies, [...]
>
> And just what workaround do you think I'm adding?
>
> HJ> [...] any make, including GNU make, will be happy.
>
> Untrue. GNU make will invoke the commands for a rule with multiple
> targets multiple times when used with -j. Bug or feature, this must
> be accomidated.
>
> For example:
>
> $ cat Makefile
> all: foo.tab.c foo.tab.h
>
> foo.tab.c foo.tab.h: foo.y
> $(YACC) -b foo -p foo -d $?
>
> $ gmake -j
> yacc -b foo -p foo -d foo.y
> yacc -b foo -p foo -d foo.y
>
> In many cases, this must be guarded against. A rule with two targets
> occured only once in the four simulator makefiles I touched. And that
> one already handled it by introducing a pseudo-target to serialize
> the make. For the above makefile, the equivalent would be:
>
> $ cat Makefile
> all: foo.tab.c foo.tab.h
>
> foo.tab.c foo.tab.h: foo-stamp
>
> foo-stamp: foo.y
> $(YACC) -b foo -p foo -d $?
> touch $@
>
> So what exactly is your complaint about my patch.
>
That is a bug in Makefile and that is why we have ylwrap. See how it is
done in ld/Makefile.*, binutils/Makefile.* and gas/Makefile.*. Do
# grep YLWRAP */Makefile.in
in binutils tree. I can anaswer any questions if those Makefile.in
files are not clear enough.
H.J.