[PATCH][PR target/94542]Don't allow PC-relative addressing for TLS data

[Segher Boessenkool]

Hi!

On Fri, Apr 10, 2020 at 06:00:45PM -0500, acsawdey wrote:
> One of the things that address_to_insn_form() is used for is determining 
> whether a PC-relative addressing instruction could be used. In 
> particular predicate pcrel_external_address and function 
> prefixed_paddi_p() both use it for this purpose. So what emerged in 
> PR/94542 is that it should be looking to see if the associated 
> symbol_ref is a TLS symbol of some kind. TLS symbols cannot be addressed 
> with PC-relative. This patch fixes both places in address_to_insn_form() 
> where it is looking at a symbol_ref.

> 2020-04-10  Aaron Sawdey  <acsawdey@linux.ibm.com>
> 
> 	PR target/94542
> 	* config/rs6000/rs6000.c (address_to_insn_form): Do not attempt to
> 	use PC-relative addressing for TLS references.

> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 2b6613bcb7e..c77e60a718f 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -24824,15 +24824,21 @@ address_to_insn_form (rtx addr,
>    if (GET_RTX_CLASS (GET_CODE (addr)) == RTX_AUTOINC)
>      return INSN_FORM_UPDATE;
>  
> -  /* Handle PC-relative symbols and labels.  Check for both local and external
> -     symbols.  Assume labels are always local.  */
> +  /* Handle PC-relative symbols and labels.  Check for both local and
> +     external symbols.  Assume labels are always local. TLS symbols
> +     are not PC-relative.  */

(Two spaces after dot).

As Will says, "... for rs6000." won't hurt.

Okay for trunk.  Thanks!


Segher