Re: [Xen-devel] [PATCH 6/6] xen: add cloc target

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.04.18 at 00:15, <sstabellini@xxxxxxxxxx> wrote:
> Add a Xen build target to count the lines of code of the source files
> built. Uses `cloc' to do the job.
> 
> Generate the list of source files from the %.o targets, append output
> to "sourcelist".
> 
> Remove sourcelist on clean, and also at the beginning of the build
> target to avoid appending to sourcelist on consequence builds. Otherwise
> one could imagine sourcelist could become large if the user builds Xen
> repeatedly without calling clean.
> 
> For the cloc target, first clean, then build to make sure all files are
> properly accounted (no partial builds).
> 
> Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

All fine, but what I'm missing is why we want something like this in the
first place.

> ---
>  xen/Makefile | 14 ++++++++++++--
>  xen/Rules.mk |  2 ++
>  2 files changed, 14 insertions(+), 2 deletions(-)

.gitignore ?

> --- a/xen/Makefile
> +++ b/xen/Makefile
> @@ -48,7 +48,7 @@ else
>  endif
>  
>  .PHONY: _build
> -_build: $(TARGET)$(CONFIG_XEN_INSTALL_SUFFIX)
> +_build: clean-sourcelist $(TARGET)$(CONFIG_XEN_INSTALL_SUFFIX)

Both here and ...

> @@ -267,3 +267,13 @@ $(KCONFIG_CONFIG):
>  include/config/auto.conf.cmd: ;
>  
>  -include $(BASEDIR)/include/config/auto.conf.cmd
> +
> +.PHONY: cloc
> +cloc: $(BASEDIR)/sourcelist
> +     cloc --list-file=$(BASEDIR)/sourcelist
> +
> +$(BASEDIR)/sourcelist: clean build

... here I'm afraid the dependencies aren't right: All dependencies can
be handled in parallel by make, i.e. there's no ordering implication from
the ordering you provide here.

> --- a/xen/Rules.mk
> +++ b/xen/Rules.mk
> @@ -190,9 +190,11 @@ _clean_%/: FORCE
>       $(MAKE) -f $(BASEDIR)/Rules.mk -C $* clean
>  
>  %.o: %.c Makefile
> +     echo `pwd`/$< >> $(BASEDIR)/sourcelist
>       $(CC) $(CFLAGS) -c $< -o $@
>  
>  %.o: %.S Makefile
> +     echo `pwd`/$< >> $(BASEDIR)/sourcelist
>       $(CC) $(AFLAGS) -c $< -o $@

For one I'd prefer if this file was written only when actually processing
the "cloc" target you add. And then - is echo guaranteed to produce all
its output with a single atomic write? Otherwise you risk producing a
complete mess in sourcelist if someone hands -j to make.

Furthermore - are e.g. header files not counting at all?

Jan



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