https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #10 from peterz at infradead dot org ---
On Fri, Mar 14, 2025 at 09:41:07AM +, jakub at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
>
> --- Comment #9 from Jakub Jelinek ---
> (In reply to peterz
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #8 from peterz at infradead dot org ---
On Fri, Mar 14, 2025 at 08:44:19AM +, torva...@linux-foundation.org wrote:
> Now, I agree that the kernel could likely solve issues by just "don't check so
> much, then". But our build-time
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #9 from Jakub Jelinek ---
(In reply to peterz from comment #8)
> There is the additional constraint that as long as the frame pointer
> unwinder does not have to guess, it is assumed to be 100% correct.
>
> By having calls before fr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #7 from Jakub Jelinek ---
In any case, I agree with Richi that
__builtin_frame_address_(0)
is the right thing, even when the inline asm doesn't use itself %rbp, the
dependency on %rbp is what is needed in the compiler so that
post-pr
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #6 from Linus Torvalds ---
(In reply to Jakub Jelinek from comment #5)
> Call instructions are normally valid anywhere in the function, including
> prologue and epilogue, even with frame pointers.
Sure, the call instruction actually
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #4 from Linus Torvalds ---
(In reply to Richard Biener from comment #3)
> I think
>
> asm ("" : : "g" (__builtin_frame_address_(0)))
>
> and using that input as frame pointer looks spot-on semantically, is that
> what you are actua
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #5 from Jakub Jelinek ---
Call instructions are normally valid anywhere in the function, including
prologue and epilogue, even with frame pointers.
E.g. for
void bar (char *);
void
foo (void)
{
char a[1024];
bar (a);
bar (a);
}
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #3 from Richard Biener ---
I think
asm ("" : : "g" (__builtin_frame_address_(0)))
and using that input as frame pointer looks spot-on semantically, is that
what you are actually using or are you then using %rbp anyway in the
assemb
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
Andrew Pinski changed:
What|Removed |Added
Last reconfirmed||2025-03-13
Status|UNCONFIRM
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119279
--- Comment #2 from Linus Torvalds ---
(In reply to Andrew Pinski from comment #1)
>
> Why is the call needs to be done in the inline-asm?
Typically it's the fallback alternative for when the primary inline asm doesn't
work
Ie the "real" asm
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