* Petr Hosek <phosek@chromium.org> [2015-11-12 00:28:44 +0000]:
> On Wed, Nov 11, 2015 at 3:09 PM Rich Felker <dalias@libc.org> wrote:
> > On Wed, Nov 11, 2015 at 10:02:50PM +0000, Petr Hosek wrote:
> > >  MEMOPS_SRCS = src/string/memcpy.c src/string/memmove.c
> > src/string/memcmp.c src/string/memset.c
> > >  $(MEMOPS_SRCS:%.c=%.o) $(MEMOPS_SRCS:%.c=%.lo): CFLAGS_ALL +=
> > $(CFLAGS_MEMOPS)
> > > @@ -119,34 +144,35 @@ $(CRT_LIBS:lib/%=crt/%): CFLAGS_ALL += -DCRT
> > >  # force the corresponding object file to be rebuilt, even if the
> > implicit
> > >  # rule below goes indirectly through a .sub file.
> > >  define mkasmdep
> > > -$(dir $(patsubst %/,%,$(dir $(1))))$(notdir $(1:.s=.o)): $(1)
> > > +$(dir $(patsubst $(srcdir)/%/,%,$(dir $(1))))$(notdir $(1:.s=.o)): $(1)
> > > +$(dir $(patsubst $(srcdir)/%/,%,$(dir $(1))))$(notdir $(1:.s=.lo)): $(1)
> > >  endef
> > > -$(foreach s,$(wildcard src/*/$(ARCH)*/*.s),$(eval $(call
> > mkasmdep,$(s))))
> > > +$(foreach s,$(wildcard $(srcdir)/src/*/$(ARCH)*/*.s),$(eval $(call
> > mkasmdep,$(s))))
> >
> > Was this missing the dep rules for .lo files?
> >
>
> I'm not sure how this worked before, I was getting build errors without the
> explicit dep rule for .lo files.
>
>
> > > -%.o: $(ARCH)$(ASMSUBARCH)/%.sub
> > > +$(OBJS_SUB): %.o:
> > >       $(CC) $(CFLAGS_ALL_STATIC) -c -o $@ $(dir $<)$(shell cat $<)
> > >
> > > -%.o: $(ARCH)/%.s
> > > +$(OBJS_S): %.o:
> > >       $(AS_CMD) $(CFLAGS_ALL_STATIC)
> > >
> > > -%.o: %.c $(GENH) $(IMPH)
> > > +$(OBJS_C): %.o: $(srcdir)/%.c $(GENH) $(IMPH)
> > >       $(CC) $(CFLAGS_ALL_STATIC) -c -o $@ $<
> > >
> > > -%.lo: $(ARCH)$(ASMSUBARCH)/%.sub
> > > +$(LOBJS_SUB): %.lo:
> > >       $(CC) $(CFLAGS_ALL_SHARED) -c -o $@ $(dir $<)$(shell cat $<)
> > >
> > > -%.lo: $(ARCH)/%.s
> > > +$(LOBJS_S): %.lo:
> > >       $(AS_CMD) $(CFLAGS_ALL_SHARED)
> > >
> > > -%.lo: %.c $(GENH) $(IMPH)
> > > +$(LOBJS_C): %.lo: $(srcdir)/%.c $(GENH) $(IMPH)
> > >       $(CC) $(CFLAGS_ALL_SHARED) -c -o $@ $<
> >
> > I don't understand these rules with two :'s. I assume it's some trick
> > I don't yet know. But in the case of the %.s ones, the new rules have
> > no %.s in them... this looks wrong, no?
> >
>
> This is bit of hack which uses the static rules. I think we might be able
> to get rid of those if we remove the *.sub system as mentioned earlier, but
> this is the only way I got it to work without having a per file rule in the
> current setup.

i'm fine with VPATH + a make time check that in/out is not mixed

this second approach is ok if there is some solution for the
%.o: %.s rules (i guess AS_CMD only works without %.s because
mkasmdeps adds the deps).

the .sub approach is not flexible and i don't see an easy way to
encode all configury bits in the directory tree
(e.g. if we ever want to allow musl to be compiled for sse4,
avx, or other more finegrained arch extensions.. maybe .S
with #ifdefs for subarch is more flexible)