Hi,
Actually, I would like to ask if all this should be tree level optimization
or there would be something to do at backend. I am asking because I am trying
to write a new backend.
thanks,
Alex R. Prado
Em 25/04/2011 14:47, Ian Lance Taylor < i...@google.com > escreveu:
cirrus75 writes:
> For the fllowing code:
>
> typedef struct {
> int f1:1;
> int f2:1;
> int f3:1;
> int f4:29;
> } t1;
>
> typedef struct {
> int f1:1;
> int f2:1;
> int f3:30;
> } t2;
>
> t1 s1;
> t2 s2;
>
> void func1(void)
> {
> s1.f1 = s2.f1;
> s1.f2 = s2.f2;
> }
>
> we get (x86_64 target):
>
> movzbl s2(%rip), %edx
> movzbl s1(%rip), %eax
> movl %edx, %ecx
> andl $-4, %eax
> andl $2, %edx
> andl $1, %ecx
> orl %ecx, %eax
> orl %edx, %eax
> movb %al, s1(%rip)
> ret
>
>
> Could gcc optimize two or more operations in adjacent bitfields into one
> operation ?
This question looks more appropriate for the mailing list
gcc-h...@gcc.gnu.org rather than the mailing list gcc@gcc.gnu.org.
I agree that this looks like suboptimal code. Please consider filing a
missed-optimization bug report. See http://gcc.gnu.org/bugs/ . Thanks.
Ian
