https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79675
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|UNCONFIRMED |RESOLVED
Target Milestone|--- |9.0
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
On the 9.3+ we get:
.L4:
ldrb w0, [x19], 1
cbz w0, .L6
.L3:
sub x20, x19, #1
cmp w21, w0
bne .L4
mov x2, x23
mov x1, x22
mov x0, x19
bl strncmp
cbnz w0, .L4
GCC 7 and 8 got us:
.L9:
beq .L8
.L4:
mov x20, x19
mov x19, x20
ldrb w1, [x19], 1
cmp w21, w1
cbnz w1, .L9
...
.L8:
.cfi_restore_state
mov x2, x22
mov x1, x23
mov x0, x19
bl strncmp
cbnz w0, .L4
Which had the moves.
GCC 9+ ch does:
Analyzing loop 1
Loop 1 is not do-while loop: latch has multiple predecessors.
Will duplicate bb 7
Not duplicating bb 1: both sucessors are in loop.
Duplicating header of the loop 1 up to edge 7->4, 4 insns.
Loop 1 is do-while loop
Loop 1 is now do-while loop.
While 8- ch has:
Analyzing loop 1
Loop 1 is do-while loop
Which means this was fixed by r9-23.
