Sometimes we would want to create lots of output files, no matter from which stage of a compiler they're from, be it preprocessor, code generation, assembly or linker stage.
For example, you have a C source file, source.c, and you need to produce object files with and without debug symbols, x86 and x86_64 versions, position independent and position dependent. How would you do it? The first thing that comes to mind is to run many times compilation with different options like that:
cc -c -g -no-pie -m32 -o source_debug_nopie_32.o hello.c
cc -c -g -no-pie -m64 -o source_debug_nopie_64.o hello.c
cc -c -g -m32 -o source_debug_pie_32.o hello.c
cc -c -g -m64 -o source_debug_pie_64.o hello.c
cc -c -no-pie -m32 -o source_nodebug_nopie_32.o hello.c
cc -c -no-pie -m64 -o source_nodebug_nopie_64.o hello.c
cc -c -m32 -o source_nodebug_pie_32.o hello.c
cc -c -m64 -o source_nodebug_pie_64.o hello.cA lot of typing, isn't it? That is how you can do it with ccgen:
ccgen -e o \
-b source \
-o -c -o -g,debug,,nodebug \
-o -no-pie,nopie,,pie \
-o -m32,32,-m64,64 \
source.cAdding a new option with ccgen is much simpler and shorter, than doing the same manually. That is, we achieve scalability.
ccgen [-l logfile]
[-x backend]
[-b outfile_base]
[-e extension]
[-o option_spec]...
args...
ccgen -h
ccgen -vIt is particularly useful to use a compiler as a backend, effectively generating a lot of files, each of which will be compiled with different options.
You pass options to ccgen, and after a little bit of transformation it will run backend with the specified options.
-b outfile_base
Choose output file base name. By default it's empty(backend defaults will be used).
-x backend
Choose backend, which _ccgen_ will run and pass options and arguments to.
Defaults to _cc_.
-o option_spec
Option specification.
_option_spec_ is a comma seperated list, which is logically divided in groups of two, each of which
specify one possible value for an option. The first element(fname, or formal name) of a group is mandatory,
and it's copied as it is to a backend. The second element(iname, or informal name) of a group is optional,
and it specifies meaning of an option for humans, which is used in output file name.
If the second field of a group is missing, it is set to empty string.
-l log_file
File, to which all of the logs will be sent.
-h
Invoke help and exit.
-v
Print version and exit.
--
Stop processing options. That is, all after that will be though of as of arguments, even
if it is started with -(dash).
args...
Remaining arguments. All are passed to backend without change.
0 on success. Some negative value otherwise.