https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108862
--- Comment #3 from Segher Boessenkool <segher at gcc dot gnu.org> ---
With -fno-unroll-loops added we get
foo:
.LFB0:
.cfi_startproc
cmpwi 0,3,0
ble 0,.L4
mtctr 3
addi 10,4,-8
addi 5,5,8
li 3,0
.p2align 4,,15
.L3:
ldu 4,8(10)
ldu 9,-8(5)
maddld 3,4,9,3
maddhdu 4,4,9,3
bdnz .L3
blr
.p2align 4,,15
.L4:
li 3,0
li 4,0
blr
(which still fails, just is easier to read).
The destinations of the four inner loop insns were 131, 132, 135, 136,
and IRA decided for those
Disposition:
18:r131 l0 4
17:r132 l0 9
1:r135 l0 3
0:r136 l0 4
and that cannot fly.
