KVM: s390: use simple switch statement as multiplexer
We currently do some magic shifting (by exploiting that exit codes
are always a multiple of 4) and a table lookup to jump into the
exit handlers. This causes some calculations and checks, just to
do an potentially expensive function call.
Changing that to a switch statement gives the compiler the chance
to inline and dynamically decide between jump tables or inline
compare and branches. In addition it makes the code more readable.
bloat-o-meter gives me a small reduction in code size:
Right now my gcc does conditional branches instead of jump tables.
The inlining seems to give us enough cycles as some micro-benchmarking
shows minimal improvements, but still in noise.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>