OpenForum RSS: GCC Accem��

GCC Accem�� (const86)

Tue, 22 Dec 2009 12:27:51 GMT

>>! __asm__ __volatile__ ("xchg %eax, %%e�x" : "=a"(x), "=�"(y) : "a"(x), "�"(y));
>>...
>>main+31: xchg %eax,%edx
>
>��...

GCC Accem�� (const86)

Tue, 22 Dec 2009 12:27:06 GMT

>! __asm__ __volatile__ ("xchg %�x, %%e�x" : "=a"(x), "=�"(y) : "a"(x), "�"(y));
>...
>main+31: xchg �x,�x

��...

GCC Accem�� (pavlinux)

Tue, 22 Dec 2009 11:49:56 GMT

>�� , �� asm �� , � �

�� 4, �� x, y: x = -4(%rbp), y = -8(%rbp)

>�� . �� , �� , ��
>�� . � �� , �� :
>
>void hyperswap(int *p, int *q) {
> int x = *p, y = *q;
> asm ("xchg %%eax, %%ecx\n" : "=a" (x), "=c" (y) : "a"
>(x), "c" (y));
> *p = x, *q = y;
>}

� �� ӣ �� EDX, � �� mov

!
! __asm__ __volatile__ ("xchg %%eax, %%e�x" : "=a"(x), "=�"(y) : "a"(x), "�"(y));
main+22: mov -0x8(%rbp),%eax
main+25: mov -0x4(%rbp),%e�x
main+28: mov %e�x, %edx :)
main+31: xchg %eax,%edx
main+32: mov %eax,-0x8(%rbp)
main+33: mov %edx,-0x4(%rbp)
!

�� .

__asm__ __volatile__ ("xchg %%eax, %%edx" : "=a"(x), "=d"(y) : "a"(x), "d"(y));

GCC Accem�� (const86)

Tue, 22 Dec 2009 07:44:00 GMT

> xchg %edx, %eax # ��
>
> movl %edx, -8(%rbp) # �� edx � b
> movl %eax, -4(%rbp) # � eax � a

��! � �� , �� movl, �� edx � eax - � xchg �� !

�� , �� asm �� , � � �� . �� , �� , �� . � �� , �� :

void hyperswap(int *p, int *q) {
int x = *p, y = *q;
asm ("xchg %%eax, %%ecx\n" : "=a" (x), "=c" (y) : "a" (x), "c" (y));
*p = x, *q = y;
}

GCC Accem�� (pavlinux)

Tue, 22 Dec 2009 01:00:01 GMT

>#define swap(a, b) __asm__ __volatile__ (\
>
> "xchg %0, %1"
> \
> : "=r"(a), "=r"(b) \
>
> : "r"(b), "r"(a));

�� :

��
movl -4(%rbp), %eax # �� a = 'X';
movl -8(%rbp), %edx # �� b = 'Z';

xchg %edx, %eax # ��

movl %edx, -8(%rbp) # �� edx � b
movl %eax, -4(%rbp) # � eax � a

��?

OpenForum RSS: GCC Accem����

GCC Accem���� (const86)

GCC Accem���� (const86)

GCC Accem���� (pavlinux)

GCC Accem���� (const86)

GCC Accem���� (pavlinux)

OpenForum RSS: GCC Accem��

GCC Accem�� (const86)

GCC Accem�� (const86)

GCC Accem�� (pavlinux)

GCC Accem�� (const86)

GCC Accem�� (pavlinux)