On Fri, 14 Sep 2018, Dudziak Krzysztof wrote:
Actually question asked initially here does not seem to exist as preprocessing
then compilation is one single step. Both ...CFLAGS and ...CPPFLAGS should go
to that building stage.
Eventually the order matters, i.e. their's placement in gcc command line string.
Question asked initially might exist if to replace ax_pthread-generated
variables with gcc's -pthread option as question's objective.
gcc's manual describes it as gcc process driver's option. Latter one translates
it and passes it to preprocessor, compiler and linker flags.
But how to use -pthread in Makefile.am if makefile carries out building in two
steps, compilation then linking (with libtool in between
which possibly is irrelevant here)?
I believe automake-generated makefile by default work that way.
Libtool attempts to use the C compiler when linking, if at all
possible. In this case the C compiler is also supplied with CFLAGS
content. If the C compiler is not used for linking, then libtool
needs to assure that options passed to the linker are compatible with
it, and avoid passing options which might cause it to fail.
Libtool does remember if the -pthread option (or equivalent) was
supplied due to storing this information in the ".la" files it writes.
It is not good to only refer to GCC since there are many other
compilers. For some compilers (e.g. on IBM AIX), a different compiler
program needs to be selected in order to support pthreads.
Bob
krzysiek
-----Original Message-----
From: Bob Friesenhahn [mailto:bfrie...@simple.dallas.tx.us]
Sent: Thursday, 12. July 2018 20:28
To: Dudziak Krzysztof <krzysztof.dudz...@gemalto.com>
Cc: automake@gnu.org
Subject: Re: PTHREAD_CFLAGS provided by AX_PTHREAD where best to be attached?
On Thu, 12 Jul 2018, Dudziak Krzysztof wrote:
Hi,
For makefiles which build piece of software in two separate steps:
compilation then linking, will it be better to attach PTHREAD_CFLAGS to
higher-level_CPPFLAGS than to higher-level_CFLAGS variable?
Autotools along with libtool are used here, user-level variables (CFLAGS,
CPPFLAGS) are not manipulated through whole build chain.
I can manipulate variables only at Makefile.am -level.
CPPFLAGS is for the pre-processor while CFLAGS is applied (as well as
CPPFLAGS) while compiling. This means that putting the options in CFLAGS does
work, although it would be better to deduce which options are for the
pre-processor or the compiler and put them in the correct places.
I learned gcc expects -pthread option which translates among others to
some preprocessor define, therefore I wonder if it won't be better to
attach PTHREAD_CFLAGS to higher-level_CPPFLAGS rather than to
higher-level_CFLAGS.
It should not work to put -pthread in CPPFLAGS since it is a compiler-driver
option and not a pre-processor (e.g. /usr/bin/cpp) option.
Only, -I, -D, and -U type options (see the manual page for 'cpp') should be put
in CPPFLAGS.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us,
https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.simplesystems.org%2Fusers%2Fbfriesen%2F&data=02%7C01%7CKrzysztof.Dudziak%40gemalto.com%7C2cfd69413ad6444ed36708d5e8254424%7C37d0a9db7c464096bfe31add5b495d6d%7C1%7C1%7C636670169138687886&sdata=kqlLph71vuW%2BBZ0PKC5ew2Xb%2FFRRIIzTrCyMuvFU2Sk%3D&reserved=0
GraphicsMagick Maintainer,
https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.GraphicsMagick.org%2F&data=02%7C01%7CKrzysztof.Dudziak%40gemalto.com%7C2cfd69413ad6444ed36708d5e8254424%7C37d0a9db7c464096bfe31add5b495d6d%7C1%7C1%7C636670169138687886&sdata=Fii3vstOw5Se1obwRwfN41COxKBnqZrNbpZ2aGl1e2o%3D&reserved=0
________________________________
This message and any attachments are intended solely for the addressees and may
contain confidential information. Any unauthorized use or disclosure, either
whole or partial, is prohibited.
E-mails are susceptible to alteration. Our company shall not be liable for the
message if altered, changed or falsified. If you are not the intended recipient
of this message, please delete it and notify the sender.
Although all reasonable efforts have been made to keep this transmission free
from viruses, the sender will not be liable for damages caused by a transmitted
virus.
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
