[Bug target/54682] [SH] Replace constant loads with reg-reg copies

[olegendo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54682

--- Comment #3 from Oleg Endo <olegendo at gcc dot gnu.org> ---
A related case from CSiBE, linux-2.4.23-pre3-testplatform/net/ipv4/igmp.c,
function _add_grhead:

.L275:
        mov     #0,r0
        mov.b   r11,@r8
        mov.b   r0,@(1,r8)
        mov     #0,r0        << redundant constant load
        mov.w   r0,@(2,r8)
        mov.l   @(4,r10),r1
        mov.l   r1,@(4,r8)
        mov.l   @(32,r9),r1
        mov.w   @(6,r1),r0

The redundant load of 'r0' with constant '0' is probably introduced by reload. 
If converted to 'mov r0,r0' it would probably be eliminated automatically.