https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61578
--- Comment #19 from Fredrik Hederstierna
<fredrik.hederstie...@securitas-direct.com> ---
I'm not sure why bug 59535 was closed, same problem might still exist, quote:
> Zhenqiang Chen 2014-09-03 06:17:44 UTC
>
> Here is a small case to show lra introduces one more register copy (tested
> with trunk and 4.9).
int isascii (int c)
{
return c >= 0 && c < 128;
}
With options: -Os -mthumb -mcpu=cortex-m0, I got
isascii:
mov r3, #0
mov r2, #127
mov r1, r3 //???
cmp r2, r0
adc r1, r1, r3
mov r0, r1
bx lr
With options: -Os -mthumb -mcpu=cortex-m0 -mno-lra, I got
isascii:
mov r2, #127
mov r3, #0
cmp r2, r0
adc r3, r3, r3
mov r0, r3
bx lr
Testing 4.8.5 and 5.2.0 still still produces same bigger code in GCC 5.2.
So something adds a register copy in this small case.
/Fredrik
