Re: [RFA]: simulator build failures with parallel make

[jtc@redback.com (J.T. Conklin)]

>>>>> "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.

        --jtc

-- 
J.T. Conklin
RedBack Networks