[RFC 6/6] aarch64 gas: Free reg alias entries before exit

[Matthieu Longo]

On 03/03/2026 12:41, Alice Carlotti wrote:
> Add a deletion hook to aarch64_reg_hsh, so that dynamically allocated
> data in alias entries is freed at exit.  This removes the allocations
> from LeakSanitizer reports, and also allows the explicit 'free' calls to
> be removed from s_unreq ().
> 
> 
> diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
> index 3dde65e3d91e346bd271189f11d119f78355a92d..2c78f990502fb06c61b3d85142ded7036051d7db 100644
> --- a/gas/config/tc-aarch64.c
> +++ b/gas/config/tc-aarch64.c
> @@ -1711,6 +1711,21 @@ create_register_alias (char *newname, char *p)
>     return true;
>   }
>   
> +/* Delete handler for aarch64_reg_hsh.  Builtin reg entries are static values
> +   added at startup, while aliases are dynamically allocated.  */
> +
> +static void
> +free_register_entry (void *entry)
> +{
> +  string_tuple_t *tuple = entry;
> +  reg_entry *reg = (reg_entry *) tuple->value;
> +  if (!reg->builtin)
> +  {
> +    free ((char *) reg->name);
> +    free (reg);
> +  }
> +}
> +
>   /* Should never be called, as .req goes between the alias and the
>      register name, not at the beginning of the line.  */
>   static void
> @@ -1753,8 +1768,6 @@ s_unreq (int a ATTRIBUTE_UNUSED)
>   	  char *nbuf;
>   
>   	  str_hash_delete (aarch64_reg_hsh, name);
> -	  free ((char *) reg->name);
> -	  free (reg);
>   
>   	  /* Also locate the all upper case and all lower case versions.
>   	     Do not complain if we cannot find one or the other as it
> @@ -1767,8 +1780,6 @@ s_unreq (int a ATTRIBUTE_UNUSED)
>   	  if (reg)
>   	    {
>   	      str_hash_delete (aarch64_reg_hsh, nbuf);
> -	      free ((char *) reg->name);
> -	      free (reg);
>   	    }
>   
>   	  for (p = nbuf; *p; p++)
> @@ -1777,8 +1788,6 @@ s_unreq (int a ATTRIBUTE_UNUSED)
>   	  if (reg)
>   	    {
>   	      str_hash_delete (aarch64_reg_hsh, nbuf);
> -	      free ((char *) reg->name);
> -	      free (reg);
>   	    }
>   
>   	  free (nbuf);
> @@ -10583,7 +10592,6 @@ md_begin (void)
>     aarch64_sys_regs_plbi_hsh = str_htab_create ();
>     aarch64_sys_regs_mlbi_hsh = str_htab_create ();
>     aarch64_sys_regs_sr_hsh = str_htab_create ();
> -  aarch64_reg_hsh = str_htab_create ();
>     aarch64_barrier_opt_hsh = str_htab_create ();
>     aarch64_nzcv_hsh = str_htab_create ();
>     aarch64_pldop_hsh = str_htab_create ();
> @@ -10592,6 +10600,11 @@ md_begin (void)
>     aarch64_sys_ins_gicr_hsh = str_htab_create ();
>     aarch64_sys_ins_gsb_hsh = str_htab_create ();
>   
> +  /* This is equivalent to str_htab_create with an added deletion hook.  */
> +  aarch64_reg_hsh = htab_create_alloc (16, hash_string_tuple, eq_string_tuple,
> +				       free_register_entry, notes_calloc,
> +				       NULL);
> +
>     fill_instruction_hash_table ();
>   
>     for (i = 0; aarch64_sys_regs[i].name != NULL; ++i)

Ok.

Matthieu