sparc "environments" versus -mcpu=...

[lucier@math.purdue.edu]

The documentation for -m32 and -m64 on sparc says

>  Generate code for a 32-bit or 64-bit environment.

Is this totally independent of what I set for -mcpu=...?  For example,
I thought that if I set -mcpu=supersparc with a sparcv9-sun-solaris2.8
version of gcc, it would default to -m32 since the 64-bit environment
is not supported on sparcv8.  But if I leave out the -m32, gcc ICE's on
a file with the command line

  gcc -fPIC -O1 -fschedule-insns2 -fno-strict-aliasing -fno-math-errno -mcpu=supersparc -mtune=ultrasparc -Wall -W -Wno-unused -c -I../lib  -D___SHARED -D___SINGLE_HOST setup.c

Is my understanding incorrect?  Or is it incorrect to require -m32 with
-mcpu=supersparc?

Brad