https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53976
Oleg Endo <olegendo at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2014-08-13
Summary|[SH] Unnecessary clrt after |[SH] Unnecessary clrt/sett
|bt |after bt/bf
Ever confirmed|0 |1
--- Comment #8 from Oleg Endo <olegendo at gcc dot gnu.org> ---
Another case that could be handled is trying to invert comparisons so that
conditional branches from multiple basic blocks have the same T bit value.
The following code:
static const int table[] = { 0, 1, 2, 3, 4, 9, 10, 42 };
int test (int n)
{
return *std::lower_bound (std::begin (table), std::end (table), n);
}
compiled with -m2 -ml -Os:
mov.l .L37,r3
mov #8,r1
.L33:
cmp/pl r1
bf.s .L36
mov r1,r7
shar r7
mov r7,r2
shll2 r2
add r3,r2
mov.l @r2,r6
cmp/ge r4,r6 <<<
bt .L35 <<<
mov r2,r3
sett <<<
add #4,r3
bra .L33
subc r7,r1
.L35:
bra .L33
mov r7,r1
.L36:
rts
mov.l @r3,r0
.L38:
.align 2
.L37:
.long __ZN5test5L5tableE
In this case 'cmp/ge r4,r6; bt .L35' can be changed to 'cmp/gt r6,r4; bf .L35'
and the sett insn can be eliminated.
