yet another test case: long long usage generates horrific code

[Ben LaHaise]

The following assembly (ak! ptewy!) is generated with

 gcc -O2 -Wall -fomit-frame-pointer -S longlong.c

in a recent snapshort of gcc used in Red Hat on x86.

test3:
	pushl	%edi
	pushl	%esi
	xorl	%ecx, %ecx
	pushl	%ebx
	movl	16(%esp), %esi
	movl	%ecx, %eax
	movl	%ecx, %edx
#APP
	cmpxchg8 (%esi)
#NO_APP
	movl	%edx, %esi
	movl	%eax, %ecx
	movl	%esi, %eax
	movl	%eax, %edx
	xorl	%eax, %eax
	xorl	%ebx, %ebx
	movl	%eax, %esi
	movl	%edx, %edi
	orl	%ebx, %edi
	orl	%ecx, %esi
	popl	%ebx
	movl	%esi, %eax
	movl	%edi, %edx
	popl	%esi
	popl	%edi
	ret
-------------------------
And the source:

long long test(void)
{
	return 0;
}

long long test2(void)
{
	return -1;
}

extern inline long long xchg64(void *ptr, long long val)
{
	unsigned long low, high;

	low = val;
	high = val >> 32;

	__asm__ __volatile__(
		"cmpxchg8 (%2)"
		: "=a" (low), "=d" (high)
		: "r" (ptr), "0" (low), "1" (high)
		:"memory");

	return ((unsigned long long)high << 32) | low;
}

long long test3(void *ptr)
{
	return xchg64(ptr, 0);
}