On Wednesday 16 February 2005 10:48 pm, Horst von Brand wrote:
> Does x86_64 use up a (freeable) register for the frame pointer or not?
> I.e., does -fomit-frame-pointer have any effect on the generated code?
{Took Linus out of the loop as he probably isn't interested}
The generated code is different for both cases but for some reason gcc has
trouble with __builtin_return_address on x86-64.
For e.g. specifying gcc -fo-f-p, a method produces following assembly.
method_1:
.LFB2:
subq $8, %rsp
.LCFI0:
movl $__FUNCTION__.0, %esi
movl $.LC0, %edi
movl $0, %eax
call printf
movl $0, %eax
addq $8, %rsp
ret
And with -fno-o-f-p, the same method yields
method_1:
.LFB2:
pushq %rbp
.LCFI0:
movq %rsp, %rbp
.LCFI1:
movl $__FUNCTION__.0, %esi
movl $.LC0, %edi
movl $0, %eax
call printf
movl $0, %eax
leave
ret
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
