sparc64: Support cbcond instructions in eBPF JIT.
cbcond combines a compare with a branch into a single instruction.
The limitations are:
1) Only newer chips support it
2) For immediate compares we are limited to 5-bit signed immediate
values
3) The branch displacement is limited to 10-bit signed
4) We cannot use it for JSET
Also, cbcond (unlike all other sparc control transfers) lacks a delay
slot.
Currently we don't have a useful instruction we can push into the
delay slot of normal branches. So using cbcond pretty much always
increases code density, and is therefore a win.
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed