Can I compile with MMX and SSE/SSE2 instruction sets ?

[Timothy Madden <terminatorul at gmail dot com>]

Hello

I just compiled glibc 2.15 on my Slackware 13.37 32-bit, gcc 4.7.0, with 
the following flags:
CFLAGS="-march=pentium4 -mtune=pentium4 -O3 -mmmx -msse -msse2 \
							-mfpmath=sse"
CXXFLAGS="-march=pentium4 -mtune=pentium4 -O3-mmmx -msse -msse2 \
							-mfpmath=sse"

./configure \
	--with-headers=/home/adrian/packages/linux-3.4.3/usr/include
	--enable-kernel=3.4.3
	--prefix=/usr

and I got a make error when I tried to do `make check` and no checks 
were run.

After trying to install in $HOME/usr, with
	env LANGUAGE=C LC_ALL=C install_root=$HOME/usr make install

and the build system tries to copy the new library over to /lib/libc, 
than I get a segfault everytime I try to start an application or run a 
command like ls, then my system no longer boots anymore

I notice that the build system still adds -march=i686 on the gcc command 
line anyway (and overrides my -march=pentium4).

Are my compile flags not supported by glibc ? Is there a way to compile 
the library with MMX and SSE instruction sets ? Can you please write in 
the INSTALL file that /lib/libc.so will still be installed with 
--prefix=/usr, even if install_root=$HOME/usr is used on the `make 
install` command line ?

More importantly: is there a way to get my system back now ? Can I copy 
/usr/lib/libc.so to /lib/libc.so ?

Thank you,
Timothy Madden