can't build x86-32 libc on x86-64 with mainline binutils

[Alexandre Oliva <aoliva@redhat.com>]

Am I the only one having trouble assembling
glibc/sysdeps/i386/fpu/e_atanh.S with -m32 with binutils mainline
toplevel-bootstrapped along with GCC trunk on x86_64?  I've hit this
for several days now, maybe several weeks? (time flies)

The assembler fails the sanity check for carry == 0 on
gas/atof-generic.c:419 on line 40 of the preprocessed asm file.  In
fact, assembling that line by itself produces the same error.

Here's how I configured the toolchain:

../configure   amd64-linux-gnu --enable-languages=all

and here's how I configured glibc:

../src/configure '--prefix=/usr' '--enable-add-ons=nptl' \
  '--without-cvs' '--with-tls' '--with-headers=/usr/include' \
  '--build=i686-pc-linux-gnu' 'CC=gcc -m32 -march=i686 -U__i686' \
  'CXX=g++ -m32 -march=i686 -U__i686'

(the ugly -U__i686 was introduced months ago; IIRC without it we'd
fail to assemble the GOT register set up routines that have __i686 in
their names in such a way that the preprocessor would expand __i686 to
1.  I haven't tried without it, I've only just realized it was still
there)

Using binutils-2.16.91.0.6-2 from the Fedora Core development tree
works.

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
Secretary for FSF Latin America        http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}