[Bug target/77882] [Aarch64] Add 'naked' function attribute

[Bug target/77882] [Aarch64] Add 'naked' function attribute

[i at maskray dot me]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77882

Fangrui Song <i at maskray dot me> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |i at maskray dot me

--- Comment #11 from Fangrui Song <i at maskray dot me> ---
The number of targets supporting this attribute is large but the popular
aarch64 somehow doesn't support it... I just run into a case where supporting
this would be nice (https://reviews.llvm.org/D126343#3536318).

% grep 'naked.*function attribute,' gcc/doc/extend.texi
@cindex @code{naked} function attribute, ARC
@cindex @code{naked} function attribute, ARM
@cindex @code{naked} function attribute, AVR
@cindex @code{naked} function attribute, C-SKY
@cindex @code{naked} function attribute, MCORE
@cindex @code{naked} function attribute, MSP430
@cindex @code{naked} function attribute, NDS32
@cindex @code{naked} function attribute, RISC-V
@cindex @code{naked} function attribute, RL78
@cindex @code{naked} function attribute, RX
@cindex @code{naked} function attribute, x86

[Bug target/77882] [Aarch64] Add 'naked' function attribute

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77882

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Fangrui Song from comment #11)
> The number of targets supporting this attribute is large but the popular
> aarch64 somehow doesn't support it... I just run into a case where
> supporting this would be nice (https://reviews.llvm.org/D126343#3536318).

That is not really a good use case really. a testcase is general purpose use
case.

[Bug target/77882] [Aarch64] Add 'naked' function attribute

[stefan.tauner at gmx dot at]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77882

stefan.tauner at gmx dot at changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |stefan.tauner at gmx dot at

--- Comment #13 from stefan.tauner at gmx dot at ---
Please reconsider this. I ran into this when debugging pointer authentication
not working correctly where I have to replace the prologue of a specific
existing non-trivial C function. This would be way easier with this attribute
and some inline assembly than replacing the whole function.

[Bug target/77882] [Aarch64] Add 'naked' function attribute

[ndesaulniers at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77882

Nick Desaulniers <ndesaulniers at google dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ndesaulniers at google dot com

--- Comment #14 from Nick Desaulniers <ndesaulniers at google dot com> ---
Adding a data point from
https://discourse.llvm.org/t/hand-written-in-assembly-in-libc-setjmp-longjmp/73249/9.

It's becoming a code portability issue when clang supports this function
attribute on functions for aarch64 targets but GCC does not.

[Bug target/77882] [Aarch64] Add 'naked' function attribute

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77882

--- Comment #15 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Nick Desaulniers from comment #14)
> Adding a data point from
> https://discourse.llvm.org/t/hand-written-in-assembly-in-libc-setjmp-longjmp/
> 73249/9.
> 
> It's becoming a code portability issue when clang supports this function
> attribute on functions for aarch64 targets but GCC does not.

Not really since you still can use a .s (or .S) file there .... That is how all
other libc implement their setjmp/longjump and even correctly. Some will even
use a generator to get the offsets and/or use static_asserts to make sure
offsets stay correct.