bootstrap fails on alphaev5-dec-osf4.0a

[Jurgen Singer]

I am trying to install egcs 1.1b on our DEC alpha machines.
However, the installation process stops with:

/fs/alpha_share/gnu/alphaev5-dec-osf4.0a/bin/as: unrecognized option `-O0'
gmake[2]: *** [libgcc2.a] Error 1
gmake[2]: Leaving directory `/bitbucket/jurgen/egcs-1.1b/objdir/gcc'
gmake[1]: *** [bootstrap] Error 2
gmake[1]: Leaving directory `/bitbucket/jurgen/egcs-1.1b/objdir/gcc'
gmake: *** [bootstrap] Error 2

I was only able to find one location in the Makefiles, where the o
ptimization is set to -O0: in  egcs-1.1b/gcc/Makefile.in: 

# We disable optimization to make floating point more reliable.
#jks 1998-10-15: ENQUIRE_CFLAGS = -DNO_MEM -DNO_LONG_DOUBLE_IO -O0
ENQUIRE_CFLAGS = -DNO_MEM -DNO_LONG_DOUBLE_IO

The above change to Makefile.in did not remedy the situation 
(even after a distclean).  The error happens with the native 
DEC as and with GNU as. The GNU as is from binutils-2.9.

I presume the -O0 option is machine generated somewhere?

Does anybody know how to circumvent the generation of this option.
Any other hints with regards to the installation on a DEC alpha are
also welcome.

-- Jurgen