Experimental Physics and
Industrial Control System

Ben Franksen <[email protected]> · Sat, 14 Jan 2017 16:52:53 +0100

Am 13.01.2017 um 18:32 schrieb Andrew Johnson:
> On 01/13/2017 10:21 AM, Mark Rivers wrote:
>> I am seeing frequent errors when building seq 2.2.4 on Linux with
>> parallel make.  This is with base 3.15.5 on a 20-core machine.
>>  
>> Sometimes it works:
>>  
>> corvette:~/support/seq-2-2-4>make -sj clean.linux-x86
>> corvette:~/support/seq-2-2-4>make -sj install.linux-x86
>> 2 parsing conflicts.
>>  
>> But often it fails:
>>  
>> corvette:~/support/seq-2-2-4>make -sj clean.linux-x86
>> corvette:~/support/seq-2-2-4>make -sj install.linux-x86
>> ../var_types.c:17:17: fatal error: snl.h: No such file or directory
>> #include "snl.h"
>>                  ^
>> compilation terminated.
>> 2 parsing conflicts.
>>  
>> Running make a second time seems to always allow the build to complete.
> 
> There's a dependency rule missing from the src/Makefile, but the rule
> gets created in the var_types.d file which is included in subsequent
> built attempts. Ben does have some rules in that Makefile and he's
> trying to support the different dependency rules in 3.14 vs 3.15, but I
> suspect GNUmake on a 20-core box is more cunning than the current rules are.
> 
> In Ben's defence it isn't easy to write Makefile rules where a single
> command generates more than one file, as seems to be the case with lemon.

Indeed. However, multiple targets are not the problem here!

The problem is that snl.h is generated *and* that the dependency (.d)
files generated by make use gcc for this.

It seems that 'gcc -MM -MF' is not able to cope with not yet existing
include files.

On our many-core build machine, I see these messages, too, but it has
gcc-4.7.2 which at least seems to be able to continue with the build.
When I go to src/snc/O.linux-x86_64 and rm -f snl.h *.d, then run make,
all the .d files are generated correctly in spite of the error messages.
When I do the same on my machine at home with gcc-5.4.0 none of the .d
files that should contain snl.h are generated. Or perhaps this is the
different make version (3.81 vs. 4.1)?

Anyway, I can suppress the error message with make-3.81/gcc-4.7.2 by
adding explicit dependencies of the relevant .d files:

lexer.o: snl.h
type_check.o: snl.h
var_types.o: snl.h

The other combination (make-4.1/gcc-5.4.0) is not able to complete
successfully when run directly after rm -f snl.h *.d, even with these
extra dependencies listed. A regular parallel build succeeds, but that
may be due to me not having enough cores.

I dimly remember that the EPICS build system offers an alternative to
using gcc to generate the .d files. Perhaps I should use that here? Any
other recommendations?

Cheers
Ben

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System