Dear Autoconf developers,
Does Autoconf have any support to generate a config.h which
can support multiple architectures, or multiple ABI, or
multiple data-model?
Recently I was asked to generate a config.h which can
support multiple architechtures of Mac OS X. Apple
extended gcc to execute multiple compilation by single
command. Aslike, if I execute:
gcc -arch ppc -arch i386 -arch ppc64 -arch x86_64 -c xxx.c
Apple's modified gcc executes 4 compilation in backgrounds:
gcc -arch ppc -c xxx.c -o /path_for_ppc/xxx.o
gcc -arch i386 -c xxx.c -o /path_for_i386/xxx.o
gcc -arch ppc64 -c xxx.c -o /path_for_ppc64/xxx.o
gcc -arch x86_64 -c xxx.c -o /path_for_x86_64/xxx.o
Then, 4 objects files are packed in single object file
(so-called "universal binary" format).
If I execute configure with such options (one of the
architechture is native), aslike:
env CC="gcc -arch ppc -arch ppc64" ./configure
on PPC machine, configure script works as usual if it's
executed for single architecture on native system, and
generates config.h successfully.
Nothing to say, some of the checked values are dependent
with architecture (ppc|ppc64), or data model (LP32|LP64),
or ABI (QuickDraw framework for ppc64 is unavailable).
So, some people tell such values should not be checked
by configure, and should not be written in config.h.
I think it's simple and reasonable solution.
# Mac OS X is the only system I know that executes multiple
# compilation by single command, but similar request
# (single config.h should support multiple architechtures)
# are raised by AMD64-system users, because their system
# can execute i386 code & amd64 code.
However, still I want configure to check such values and
write them in config.h, with appropriate conditionals.
Because,
* sometimes, cpp technique to check such values in
compilation time is not easy. when I write a pre-C99
cpp conditional to check the data model LP32 or LP64,
it bloats 100 line:
http://lists.gnu.org/archive/html/freetype-devel/2008-07/msg00010.html
* sometimes, it is impossible to guess the availability
of a feature by the combination of standard macros.
for example, the availability of PTHREAD cannot be
written by the combination of standard macros in C89.
So, now I'm thinking of writing a configure that can
execute some checking for each architechtures and merge
them with appropriate conditionals. The outline I'm
thinking of is following:
# --------------------------------------------------------
dnl
dnl arch-free checking
dnl
...
orig_CC=${CC}
dnl
dnl make a list of symbolic name of architectures
dnl because arch-speficying CFLAGS may includes a delimiter
dnl and, make variables to get CFLAGS from symbolic names.
dnl
list_of_arch_names=""
for cflags_for_an_arch in ${list_of_cflags_for_arch}
do
arch_name=`cflags-to-arch-name ${cflags_for_an_arch}`
cpp_cond=`arch-to-cpp-cond ${cflags_for_an_arch}`
list_of_arch_names="${list_of_arch_names} ${arch_name}"
eval cflags_for_arch_${arch_name}=${cflags_for_an_arch}
eval cond_for_arch_${arch_name}=${cpp_cond}
done
for an_arch in ${list_of_arch_names}
do
CC="${orig_CC} ${cflags_for_an_arch}"
dnl
dnl arch-dependent checking
dnl
AC_CHECK_SIZEOF([...])
...
dnl
dnl move values obtained by arch-dependent checking
dnl
cond='echo $cond_for_arch_'${arch_name}
cond=`echo ${cond}`
echo >> sample.h '#ifdef '${cond}
echo >> sample.h '# define SIZEOF_XXX '${ac_cv_sizeof_xxx}
...
echo >> sample.h '#endif'
unset ac_cv_...
...
done
CC=${orig_CC}
# --------------------------------------------------------
A few small tools are needed.
1. A tool used in configure.ac, to maintain the arch-dependent
values checked by configure. They should be flushed when
a serie of arch-dependent checks is finished.
KSH and BASH have a feature ${!prefix*} to obtain a list
of shell variables with prefix, so it is possible to
get a list of arch-dependent values by the comparison of
the list of variable before arch-dependent checking and
after arch-dependent checking. But I don't have good idea
applicable to real Bourne shell.
2. A tool to obtain to find cpp conditional to specify an arch.
In the outline in above, I called "arch-to-cpp-cond":
cpp_cond=`arch-to-cpp-cond ${cflags_for_an_arch}`
If we restrict the scope to GCC, "-dD" option is very
useful to get a list of predefined cpp macros. I attached
a sample sh script "cpp-cond.sh" to choose a cpp macro
which can specify an architecture. It works aslike:
$ env CC=gcc ./cpp-cond.sh "-march=i386" "-march=i486"
checking cpp macro specific to -march=i386... __tune_i386__
checking cpp macro specific to -march=i486... __tune_i486__
At present, I don't have good idea to work with non-GNU
C compilers without "-dD" option.
3. A tool to convert CFLAGS (multi-word must be accepted) to
appropriate arch name. In the outline in above, I called
"cflags-to-arch-name",
arch_name=`cflags-to-arch-name ${cflags_for_an_arch}`
4. A tool to merge multiple config.h with appropriate
cpp conditionals.
In the outline in above, the expected building procedure
is Mac OS X, single command line causes multi-arch
compilation.
Of course, most Unix systems require separated compilation
for each architectures. In such case, the arch-dependent
part in config.h should be marked in each complation,
and multiple config.h should be merged into single file.
I'm trying to write an utility to do that, but I think
such requirement may be popular and there might be existing
tool.
Anyway, if I write everything out of Autoconf, the utilization
of them makes configure.ac difficult to maintain by other people.
I wish some of them are adoped in future Autoconf. So I want to
hear the comments from Autoconf maintainers about a generation
of config.h which supports multiple architechtures.
Regards,
mpsuzuki
#!/bin/sh
trap 'rm -f confdefs.opt_*.h confdefs.*_macros.h confdefs.*.keyword' 1 2 3 9 19
num_of_opt=$#
while [ $# -gt 0 ]
do
cc_opt_name=`echo $1 | sed 's/[^0-9A-Za-z_]/_/g'`
if test x = x"${cc_opt_name}"
then
cc_opt_name="NONE"
fi
eval ${cc_opt_name}=\"$1\"
cc_opt_list="${cc_opt_list} ${cc_opt_name}"
shift
done
for cc_opt_name in ${cc_opt_list}
do
get_opt_command="echo $"${cc_opt_name}
eval cc_opt=`$get_opt_command`
eval $get_opt_command | tr ' -+=.,' '\n\n\n\n\n\n' | sort -f | uniq > confdefs.opt_${cc_opt_name}.keyword
echo | ${CC} ${CPPFLAGS} ${CFLAGS} ${cc_opt} -E -dD - | fgrep '#define' | sort -f | uniq > confdefs.opt_${cc_opt_name}.h
done
cat confdefs.opt_*.keyword | sort -f | uniq -c \
| sed -n "/^ *1 */s/^ *1 *//p" > confdefs.unique.keyword
cat confdefs.opt_*.h | awk '{printf("#define %s \n", $2)}' | sort -f | uniq -c \
| sed -n "/^ *${num_of_opt} *#/s/^ *${num_of_opt} *#/#/p" > confdefs.common_macros.h
cat confdefs.opt_*.h | sort -f | uniq -c \
| sed -n "/^ *${num_of_opt} *#/s/^ *${num_of_opt} *#/#/p" > confdefs.same_macros.h
cat confdefs.opt_*.h | awk '{printf("#define %s \n", $2)}' \
| fgrep -vf confdefs.common_macros.h | sort -f | uniq -c \
| sed -n "/^ *1 *#/s/^ *1 *#/#/p" > confdefs.uniqbool_macros.h
cat confdefs.opt_*.h | fgrep -vf confdefs.uniqbool_macros.h | sort -f | uniq -c \
| sed -n "/^ *1 *#/s/^ *1 *#/#/p" > confdefs.uniqvalue_macros.h
for cc_opt_name in ${cc_opt_list}
do
get_opt_command="echo $"${cc_opt_name}
eval cc_opt=`$get_opt_command`
echo "checking cpp macro specific to ${cc_opt}..." | tr '\n' ' '
opt_bool_macros=`fgrep -f confdefs.uniqbool_macros.h < confdefs.opt_${cc_opt_name}.h | awk '{printf(" %s", $2)}'`
opt_value_macros=`fgrep -f confdefs.uniqvalue_macros.h < confdefs.opt_${cc_opt_name}.h | sed 's/#define \([^ ]*\) /\1=/g' | tr '\n' ' '`
if test `echo ${opt_bool_macros} | wc -w` -gt 0
then
if test `echo ${opt_bool_macros} | tr ' ' '\n' | fgrep -f confdefs.unique.keyword | fgrep -f confdefs.opt_${cc_opt_name}.keyword | wc -l` -gt 0
then
opt_bool_macros=`echo ${opt_bool_macros} | tr ' ' '\n' | fgrep -f confdefs.unique.keyword | fgrep -f confdefs.opt_${cc_opt_name}.keyword | tail -1`
elif test `echo ${opt_bool_macros} | tr ' ' '\n' | fgrep -vf confdefs.unique.keyword | fgrep -if confdefs.opt_${cc_opt_name}.keyword | wc -l` -gt 0
then
opt_bool_macros=`echo ${opt_bool_macros} | tr ' ' '\n' | fgrep -f confdefs.unique.keyword | fgrep -if confdefs.opt_${cc_opt_name}.keyword | tail -1`
fi
opt_bool_macros=`echo ${opt_bool_macros} | tr ' ' '\n' | tail -1`
echo ${opt_bool_macros}
elif test `echo ${opt_value_macros} | wc -w` -gt 0
then
if test `echo ${opt_value_macros} | tr ' ' '\n' | fgrep -vf confdefs.unique.keyword | fgrep -f confdefs.opt_${cc_opt_name}.keyword | wc -l` -gt 0
then
opt_value_macros=`echo ${opt_value_macros} | tr ' ' '\n' | fgrep -f confdefs.unique.keyword | fgrep -f confdefs.opt_${cc_opt_name}.keyword | tail -1`
elif test `echo ${opt_value_macros} | tr ' ' '\n' | fgrep -vf confdefs.unique.keyword | fgrep -if confdefs.opt_${cc_opt_name}.keyword | wc -l` -gt 0
then
opt_value_macros=`echo ${opt_value_macros} | tr ' ' '\n' | fgrep -f confdefs.unique.keyword | fgrep -if confdefs.opt_${cc_opt_name}.keyword | tail -1`
fi
opt_value_macros=`echo ${opt_value_macros} | tr ' ' '\n' | tail -1`
echo ${opt_value_macros}
else
echo "not found"
fi
done
rm -f confdefs.opt_*.h confdefs.*_macros.h confdefs.*.keyword
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