[PATCH v7 02/19] gas: move code for object attribute parsing into obj-elf-attr.c

[Jan Beulich]

On 14.07.2025 18:58, Matthieu Longo wrote:
> Gas, contrarilly to others binutils tools, is compiled for a specific
> target. Some targets don't support Object Attributes (OAs). For those
> cases, today the OA directive ".gnu_attribute" is still enabled but the
> processing would probably fail in most of cases because the named tag
> would be unknown. Most of the parsing code on such a target can be
> considered as dead code.
> 
> This patch aims at removing this dead code from Gas when the target does
> not support the OAs by:
> - moving the code of OA parsing into a separate file under gas/config
>   which is only included for the relevant targets supporting OAs.
> - disabling the code related to OAs on non-OA target via a TC_OBJ_ATTR
>   macro.
> 
> Adding/removing the OA feature from Gas for a specific target can easilly
> be done from tc-<arch>.h by changing the values of TC_OBJ_ATTR: 1 enabled,
> 0 disabled. You might also want to guard the enablement of OAs only for
> ELF targets with OBJ_ELF (see example below).
> 
> \#ifdef OBJ_ELF
> /* The target supports Object Attributes.  */
> \#define TC_OBJ_ATTR 1
> \#endif

In principle okay, but see below.

> --- a/gas/config/tc-mips.h
> +++ b/gas/config/tc-mips.h
> @@ -217,4 +217,9 @@ extern bfd_reloc_code_real_type mips_cfi_reloc_for_encoding (int encoding);
>  #define CONVERT_SYMBOLIC_ATTRIBUTE(name) mips_convert_symbolic_attribute (name)
>  extern int mips_convert_symbolic_attribute (const char *);
>  
> +#ifdef OBJ_ELF
> +/* The target supports Object Attributes.  */
> +#define TC_OBJ_ATTR 1
> +#endif

Taking this as an example: On the same basis that using OBJ_MAYBE_ELF isn't
necessary here (MIPS only supporting ELF targets, and hence not supporting
a mix of object formats through emulation) you don't really need to check
OBJ_ELF here then as well.

IOW - I'd prefer if all unnecessary checks of OBJ_ELF would be stripped off
this patch.

> --- a/gas/configure.ac
> +++ b/gas/configure.ac
> @@ -454,6 +454,19 @@ changequote([,])dnl
>  	;;
>      esac
>  
> +    # Does the target support Object Attributes ?
> +    case ${cpu_type} in
> +      arc* | arm* | csky | m68k | mips* | msp430 | powerpc* \
> +      | riscv* | s390* | sparc* | tic6x)
> +	for f in config/obj-elf-attr.o; do
> +	  case " $extra_objects " in
> +	    *" $f "*) ;;
> +	    *) extra_objects="$extra_objects $f" ;;
> +	  esac
> +	done
> +	;;
> +    esac

The okay is further based on the assumption that my earlier understanding
was wrong, and Arm64 in fact didn't / doesn't support v1 object attributes.

Jan