Re: Build system adjustments for subarchs

[Rich Felker <dalias@aerifal.cx>]

On Tue, Aug 13, 2013 at 11:42:26PM -0400, Rich Felker wrote:
> > Actually, this would work great if I could write an abstract rule that
> > says roughly: for each .o target %.o, add dependencies on %.c and
> > $(wildcard */%.s). This would make it so files with asm always get
> > rebuilt if either the base C file or any of the asm versions, for any
> > arch or subarch, has been modified. Obviously in some cases the
> > rebuild would be spurious, but such files are sufficiently small that
> > I don't care; the simplicity of a universal rule with no
> > arch-dependent dependency data to maintain is much more valuable.
> > 
> > Unfortunately, I don't know a way to do this with make, but I believe
> > there should be a way...
> 
> This seems to do it, though maybe there's a more elegant way:
> 
> define archrule =
> $(dir $(patsubst %/,%,$(dir $(s))))$(notdir $(s:.s=.o)): $(s)
> endef
> 
> $(foreach s,$(wildcard src/*/$(ARCH)*/*.s),$(eval $(call archrule,$(s))))
> 
> [...]
> 
> I'm going to run some tests on arm, and it if works, I'll commit.

I think it should be $(1) rather than $(s) in the archrule, but for
some reason, the $(eval ...) is not doing _anything_ on make 3.81 on
my Debian box. With my usual make 3.82, it works fine. This is not
really a show-stopper, since no errors occur; it just means
dependencies aren't getting honored on some versions of make that
might still be out there in the wild. But I would very much appreciate
some insight on why this is happening, from any GNU make experts...

Rich