On Tue, Jun 21, 2022 at 10:03:18AM +0800, Kewen.Lin wrote:
> This case also needs effective-target keyword lp64,
> that is /* { dg-require-effective-target lp64 } */
Good point. Yes.
It would be nice to have just has_arch_ppc64 really.
> since with -m32, it gets:
> mr 3,4
>
> with -m32 -mpowerpc64, it gets:
> rldicl 3,4,0,32
Yes, and that is not lp64 -- both longs and pointers are 32 bits when
you have -m32.
You get different code because parameter passing is different. The
usual way to sidestep is to have the data in memory instead:
unsigned long long x;
void
goo (void)
{
unsigned long long value = x;
value &= 0xffffffff;
value |= value << 32;
x = value;
}
but then the compiler tries to be smart and do code like
addis 10,2,.LANCHOR0+4@toc@ha
lwz 10,.LANCHOR0+4@toc@l(10)
sldi 9,10,32
add 9,9,10
addis 10,2,.LANCHOR0@toc@ha
std 9,.LANCHOR0@toc@l(10)
blr
for -m64, and
lis 9,x@ha
la 10,x@l(9)
lwz 10,4(10)
stw 10,x@l(9)
blr
for just -m32, but
lis 10,x@ha
la 9,x@l(10)
la 10,x@l(10)
ld 9,0(9)
rldicl 8,9,0,32
sldi 9,9,32
add 9,9,8
std 9,0(10)
blr
for -m32 -mpowerpc64 (note it has not managed to do the splitter here;
it gets
Failed to match this instruction:
(set (reg:DI 128)
(plus:DI (ashift:DI (reg/v:DI 117 [ value ])
(const_int 32 [0x20]))
(zero_extend:DI (subreg:SI (reg/v:DI 117 [ value ]) 4))))
and then
Failed to match this instruction:
(set (reg:DI 128)
(plus:DI (and:DI (reg/v:DI 117 [ value ])
(const_int 4294967295 [0xffffffff]))
(ashift:DI (reg/v:DI 117 [ value ])
(const_int 32 [0x20]))))
but that is not enough).
So let's just do lp64, at least for now :-)
Segher
