Christophe Leroy [off-list ref] wrote on 2014/09/19 15:57:56:

Subject: [PATCH 2/2] powerpc32: add support for csum_add()

The C version of csum_add() as defined in include/net/checksum.h gives 

the

following assembly:
       0:       7c 04 1a 14     add     r0,r4,r3
       4:       7c 64 00 10     subfc   r3,r4,r0
       8:       7c 63 19 10     subfe   r3,r3,r3
       c:       7c 63 00 50     subf    r3,r3,r0

include/net/checksum.h also offers the possibility to define an arch 

specific

function.
This patch provides a ppc32 specific csum_add() inline function.

Signed-off-by: Christophe Leroy <redacted>

---

Ouch, this is still so. Back in 2010 I reported this to gcc:
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43892

Anyway, 
        Acked-by: Joakim Tjernlund [off-list ref]