http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50749
--- Comment #8 from Oleg Endo <oleg.e...@t-online.de> 2011-11-28 22:31:44 UTC
---
(In reply to comment #7)
> The problem is that SH target can't do those simple array accesses
> well at QI/HImode because of the lack of displacement addressing
> for those modes.
In these particular cases, this is true. Even if there was a working QI/HImode
displacement addressing, it would most likely result in worse code compared to
post-inc / pre-dec addressing opportunities, because of register pressure on
R0. Apart from that there is no displacement addressing for FPU loads/stores,
which also misses some opportunities:
float test_func_5 (float* p, int c)
{
float r = 0;
do
{
r += *p++;
r += *p++;
r += *p++;
} while (--c);
return r;
}
Compiled with -Os -m4-single:
fldi0 fr0
.L11:
mov r4,r1
fmov.s @r1+,fr1
dt r5
fadd fr1,fr0
fmov.s @r1,fr1
mov r4,r1
add #8,r1
add #12,r4
fadd fr1,fr0
fmov.s @r1,fr1
bf/s .L11
fadd fr1,fr0
rts
nop
..could be:
fldi0 fr0
.L11:
fmov.s @r4+,fr1
dt r5
fadd fr1,fr0
fmov.s @r4+,fr1
fadd fr1,fr0
fmov.s @r4+,fr1
bf/s .L11
fadd fr1,fr0
rts
nop
Specifying -fno-tree-forwprop doesn't seem to have any effect on these cases.
