Re: [FFmpeg-devel] [PATCH 1/2] ffbuild: compose linker response files in a loop

[Ramiro Polla <ramiro.polla@gmail.com>]

Hi,

On Sat, Mar 22, 2025 at 5:33 AM Gyan Doshi <ffmpeg@gyani.pro> wrote:
> On 2025-03-22 03:29 am, Martin Storsjö wrote:
> > On Fri, 21 Mar 2025, Gyan Doshi wrote:
> >> ffbuild/library.mak | 7 +++++--
> >> 1 file changed, 5 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/ffbuild/library.mak b/ffbuild/library.mak
> >> index 7e1871b74c..15302852ec 100644
> >> --- a/ffbuild/library.mak
> >> +++ b/ffbuild/library.mak
> >> @@ -36,7 +36,8 @@ endif
> >> $(SUBDIR)$(LIBNAME): $(OBJS) $(STLIBOBJS)
> >>     $(RM) $@
> >> ifeq ($(AR_OBJS),true)
> >> -    $(Q)echo $^ > $@.objs
> >> +    -$(RM) $@.objs
> >> +    $(Q)$(foreach ARG,$^,echo -n "$(ARG) " >> $@.objs;)
> >
> > Does this instance even work, it looks broken, like it is missing
> > something?
>
> Tested both static and shared building. All working with no noticeable
> speed difference although I didn't formally bench.

It's generally a good idea to check for and report the speed
differences. Even if just for the sake of curiosity.

> >>     $(AR) $(ARFLAGS) $(AR_O) @$@.objs
> >> else
> >>     $(AR) $(ARFLAGS) $(AR_O) $^
> >> @@ -73,7 +74,9 @@ $(SUBDIR)$(SLIBNAME): $(SUBDIR)$(SLIBNAME_WITH_MAJOR)
> >> $(SUBDIR)$(SLIBNAME_WITH_MAJOR): $(OBJS) $(SHLIBOBJS) $(SLIBOBJS)
> >> $(SUBDIR)lib$(NAME).ver
> >>     $(SLIB_CREATE_DEF_CMD)
> >> ifeq ($(AR_OBJS),true)
> >> -    $(Q)echo $$(filter %.o,$$^) > $$@.objs
> >> +    -$(RM) $$@.objs
> >> +    $(Q)$(eval LDARGS=$$(filter %.o,$$^))
> >> +    $(Q)$(foreach ARG,$$(LDARGS),echo -n "$(ARG) " >> $$@.objs;)
> >
> > Wouldn't this be quite significantly slow on msys2, where process
> > creation is much slower than on unix? I think it's not worth to make
> > things that much slower (which I only guess here) to fix a
> > hypothetical issue.

GNU make suggests using its file function for that:
https://www.gnu.org/software/make/manual/html_node/File-Function.html

Ramiro
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