https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62178
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Even -fno-ivopts produces better code:
.L3:
add x0, x5, x1, sxtw
add w1, w1, 1
ldr d2, [x3], 124
ldr w0, [x4, x0, lsl 2]
dup v0.2s, w0
mla v1.2s, v0.2s, v2.2s
subs w2, w2, #1
bne .L3
Compared with:
.L3:
lsl x2, x0, 5
add x1, x0, x4
sub x2, x2, x0
add x1, x1, x5
ldr d2, [x3, x2]
add x0, x0, 4
ldr w1, [x1, 4]
dup v0.2s, w1
mla v1.2s, v0.2s, v2.2s
cmp x0, 120
bne .L3
But I think the main reason for the performance regression is:
ldr w1, [x1, 4]
dup v0.2s, w1
If the compiler had used ldr1 instead the performance would be back to normal.
