Share more code between unconditional and conditional paths.
Move the computation of the trap number into the conditional BB;
avoid using temporaries that have gone out of scope (cpu_tmp32)
or rely on local temps (cpu_dst).
Fully fold the exception number when the trap number is %g0+imm.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>