The machine configure scripts are all effectively stub scripts that
pass the higher level options to its own makefile. There were only
three doing custom tests. The rest were all effectively the same as
the libc/ configure script.
So instead of recursively running configure in all of these subdirs,
generate their makefiles from the top-level configure. For the few
unique ones, deploy a pattern of including subdir logic via m4:
m4_include([machine/nds32/acinclude.m4])
Some of the generated machine makefiles have a bunch of extra stuff
added to them, but that's because they were inconsistent in their
configure libtool calls. The top-level has it, so it exports some
new vars to the ones that weren't already.
The sys configure scripts are almost all effectively stub scripts that
pass the higher level options to its own makefile. The phoenix & linux
ones are a bit more complicated with nested subdirs, so those have been
left alone for now. Plus, I don't really have a way of testing them.
There's no need to have a sys/ subdir just to copy the sys/$arch/crt0.o
up to sys/crt0.o, and then have libc/ copy sys/crt0.o up again. Just
have libc/ refer to sys/$arch/crt0.o directly and drop the intermediate
makefile entirely.
The sys/{configure,Makefile} files exist to fan out to the specific
sys/$arch/ subdir, and to possibly generate a crt0. We already have
all that same info in the libc/ dir itself, so by moving the recursive
configure and make calls into it, we can cut off some of this logic
entirely and save the overhead.
For arches that don't have a sys subdir, it means they can skip the
logic entirely.
The sys subdir itself is kept for the crt0 logic, for now. We'll try
and clean that up next.
The machine/{configure,Makefile} files exist only to fan out to the
specific machine/$arch/ subdir. We already have all that same info
in the libc/ dir itself, so by moving the recursive configure and
make calls into it, we can cut off this logic entirely and save the
overhead.
For arches that don't have a machine subdir, it means they can skip
the logic entirely. Although there's prob not too many of those.
This was added decades ago, but the commit message lacks any
explanation, and it was unused when it was merged. It's still
unused today. So punt it all.
Now that we require a recent version of autoconf, we can rely on this
macro working. This change was already made to libm, but these other
dirs were missed as I didn't notice it being duplicated in 3 places.
The AC_LIBTOOL_WIN32_DLL macro has been deprecated for a while and code
should call LT_INIT with win32-dll instead. Update the calls to match.
The generated code is noisy not because of substantial differences, but
because the order of some macros change (i.e. instead of calling AS and
then CC, CC is called first and then AS).
The newlib & libgloss dirs are already generated using autoconf-2.69.
To avoid merging new code and/or accidental regeneration using diff
versions, leverage config/override.m4 to pin to 2.69 exactly. This
matches what gcc/binutils/gdb are already doing.
The README file already says to use autoconf-2.69.
To accomplish this, it's just as simple as adding -I flags to the
top-level config/ dir when running aclocal. This is because the
override.m4 file overrides AC_INIT to first require the specific
autoconf version before calling the real AC_INIT.