powerpc/bpf/32: introduce a second source register for ALU operations
At the time being, all ALU operation are performed with same L-source
and destination, requiring the L-source to be moved into destination via
a separate register move, like:
70: 7f c6 f3 78 mr r6,r30
74: 7f a5 eb 78 mr r5,r29
78: 30 c6 ff f4 addic r6,r6,-12
7c: 7c a5 01 d4 addme r5,r5
Introduce a second source register to all ALU operations. For the time
being that second source register is made equal to the destination
register.
That change will allow, via following patch, to optimise the generated
code as:
70: 30 de ff f4 addic r6,r30,-12
74: 7c bd 01 d4 addme r5,r29
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d5aaaba50d9d6b4a0e9f0cd4a5e34101aca1e247.1675245773.git.christophe.leroy@csgroup.eu