Re: git: caab831338f4 - main - Export additional __aeabi_ symbols from arm's libgcc_s

On 28.12.2024 22:18, Dimitry Andric wrote:
> The branch main has been updated by dim:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=caab831338f4eeaa7455e981478be9fd414b7969
> 
> commit caab831338f4eeaa7455e981478be9fd414b7969
> Author:     Dimitry Andric <dim@FreeBSD.org>
> AuthorDate: 2024-12-28 21:17:13 +0000
> Commit:     Dimitry Andric <dim@FreeBSD.org>
> CommitDate: 2024-12-28 21:18:20 +0000
> 
>      Export additional __aeabi_ symbols from arm's libgcc_s
>      
>      Some programs depend on these symbols, when they are compiled for armv6
>      or armv7. Closes #1560 (slightly changed due to sorting of the symbols).
>      
>      PR:             271087
>      Reported by:    fuz
>      Submitted by:   jfc@mit.edu
>      MFC after:      1 week
> ---
>   lib/libgcc_s/arm/Symbol.map | 27 ++++++++++++++++++++++++++-
>   1 file changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/libgcc_s/arm/Symbol.map b/lib/libgcc_s/arm/Symbol.map
> index 92b54761d810..a426f823de5c 100644
> --- a/lib/libgcc_s/arm/Symbol.map
> +++ b/lib/libgcc_s/arm/Symbol.map
> @@ -4,8 +4,33 @@
>   GCC_3.5 {
>   	_Unwind_Complete;
>   	_Unwind_VRS_Get;
> -	_Unwind_VRS_Set;
>   	_Unwind_VRS_Pop;
> +	_Unwind_VRS_Set;
> +	__aeabi_d2h;
> +	__aeabi_d2lz;
> +	__aeabi_d2ulz;
> +	__aeabi_f2h;
> +	__aeabi_f2lz;
> +	__aeabi_f2ulz;
> +	__aeabi_h2f;
> +	__aeabi_idiv;
> +	__aeabi_idiv0;
> +	__aeabi_l2d;
> +	__aeabi_l2f;
> +	__aeabi_lasr;
> +	__aeabi_lcmp;
> +	__aeabi_ldivmod;
> +	__aeabi_llsl;
> +	__aeabi_llsr;
> +	__aeabi_lmul;
> +	__aeabi_ui2d;
> +	__aeabi_ui2f;
> +	__aeabi_uidiv;
> +	__aeabi_uidivmod;
> +	__aeabi_ul2d;
> +	__aeabi_ul2f;
> +	__aeabi_ulcmp;
> +	__aeabi_uldivmod;
>   	__aeabi_unwind_cpp_pr0;
>   	__aeabi_unwind_cpp_pr1;
>   	__aeabi_unwind_cpp_pr2;

I think the aeabi_ functions with floating point arguments were not 
added correctly. By definition, they must be compiled with 
-mfloat-abi=softfp event if the rest of the library is compiled with 
hardfp abi.

It is also not clear why they are added to lib/libgcc_s/arm/Symbol.map 
and not to lib/libc/arm/aeabi/Symbol.map, where the other (some now 
duplicated) aeabi_ symbols are.

Also, the list of aeabi_ functions in is not complete, although the 
compiler_rt library contains them (__aeabi_f2d, __aeabi_f2iz...).

When I looked at it, I found another problem - the whole vfp suffix 
dance in 
https://cgit.freebsd.org/src/tree/lib/libcompiler_rt/Makefile.inc#n277 
is pointless, all these functions have the same extension in their name. 
They are expected to be compiled (again with -mfloat-abi=softfp) 
together with the version without the suffix , and the rt linker will 
select the appropriate version depending on the VFP  presence.

In addition, the makefile searches for resources in the wrong order,
contrib/llvm-project/compiler-rt/lib/builtins is searched before
contrib/llvm-project/compiler-rt/lib/builtins/<arch>, so for example a 
non-specific fp_mode is built, not an architecture-specific one.

What now? For me the most important question is in which map (and 
namespace) should the aeabi_ symbols be defined (without breaking the 
ABI for the user space).

Michal