[07/22] aarch64: Add GCS builtins

  From: Szabolcs Nagy <szabolcs.nagy@arm.com>

Add new builtins for GCS:

  void *__builtin_aarch64_gcspr (void)
  uint64_t __builtin_aarch64_gcspopm (void)
  void *__builtin_aarch64_gcsss (void *)

The builtins are always enabled, but should be used behind runtime
checks in case the target does not support GCS. They are thin
wrappers around the corresponding instructions.

The GCS pointer is modelled with void * type (normal stores do not
work on GCS memory, but it is writable via the gcsss operation or
via GCSSTR if enabled so not const) and an entry on the GCS is
modelled with uint64_t (since it has fixed size and can be a token
that's not a pointer).

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.cc (enum aarch64_builtins): Add
	AARCH64_BUILTIN_GCSPR, AARCH64_BUILTIN_GCSPOPM, AARCH64_BUILTIN_GCSSS.
	(aarch64_init_gcs_builtins): New.
	(aarch64_general_init_builtins): Call aarch64_init_gcs_builtins.
	(aarch64_expand_gcs_builtin): New.
	(aarch64_general_expand_builtin): Call aarch64_expand_gcs_builtin.
---
 gcc/config/aarch64/aarch64-builtins.cc | 70 ++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
  

Yury Khrustalev <yury.khrustalev@arm.com> writes:
> From: Szabolcs Nagy <szabolcs.nagy@arm.com>
>
> Add new builtins for GCS:
>
>   void *__builtin_aarch64_gcspr (void)
>   uint64_t __builtin_aarch64_gcspopm (void)
>   void *__builtin_aarch64_gcsss (void *)
>
> The builtins are always enabled, but should be used behind runtime
> checks in case the target does not support GCS. They are thin
> wrappers around the corresponding instructions.
>
> The GCS pointer is modelled with void * type (normal stores do not
> work on GCS memory, but it is writable via the gcsss operation or
> via GCSSTR if enabled so not const) and an entry on the GCS is
> modelled with uint64_t (since it has fixed size and can be a token
> that's not a pointer).
>
> gcc/ChangeLog:
>
> 	* config/aarch64/aarch64-builtins.cc (enum aarch64_builtins): Add
> 	AARCH64_BUILTIN_GCSPR, AARCH64_BUILTIN_GCSPOPM, AARCH64_BUILTIN_GCSSS.
> 	(aarch64_init_gcs_builtins): New.
> 	(aarch64_general_init_builtins): Call aarch64_init_gcs_builtins.
> 	(aarch64_expand_gcs_builtin): New.
> 	(aarch64_general_expand_builtin): Call aarch64_expand_gcs_builtin.
> ---
>  gcc/config/aarch64/aarch64-builtins.cc | 70 ++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
>
> diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
> index 765f2091504..a42a2b9e67f 100644
> --- a/gcc/config/aarch64/aarch64-builtins.cc
> +++ b/gcc/config/aarch64/aarch64-builtins.cc
> @@ -877,6 +877,9 @@ enum aarch64_builtins
>    AARCH64_PLIX,
>    /* Armv8.9-A / Armv9.4-A builtins.  */
>    AARCH64_BUILTIN_CHKFEAT,
> +  AARCH64_BUILTIN_GCSPR,
> +  AARCH64_BUILTIN_GCSPOPM,
> +  AARCH64_BUILTIN_GCSSS,
>    AARCH64_BUILTIN_MAX
>  };
>  
> @@ -2241,6 +2244,29 @@ aarch64_init_fpsr_fpcr_builtins (void)
>  				   AARCH64_BUILTIN_SET_FPSR64);
>  }
>  
> +/* Add builtins for Guarded Control Stack instructions.  */
> +
> +static void
> +aarch64_init_gcs_builtins (void)
> +{
> +  tree ftype;
> +
> +  ftype = build_function_type_list (ptr_type_node, NULL);
> +  aarch64_builtin_decls[AARCH64_BUILTIN_GCSPR]
> +    = aarch64_general_add_builtin ("__builtin_aarch64_gcspr", ftype,
> +				   AARCH64_BUILTIN_GCSPR);
> +
> +  ftype = build_function_type_list (uint64_type_node, NULL);
> +  aarch64_builtin_decls[AARCH64_BUILTIN_GCSPOPM]
> +    = aarch64_general_add_builtin ("__builtin_aarch64_gcspopm", ftype,
> +				   AARCH64_BUILTIN_GCSPOPM);
> +
> +  ftype = build_function_type_list (ptr_type_node, ptr_type_node, NULL);
> +  aarch64_builtin_decls[AARCH64_BUILTIN_GCSSS]
> +    = aarch64_general_add_builtin ("__builtin_aarch64_gcsss", ftype,
> +				   AARCH64_BUILTIN_GCSSS);
> +}
> +
>  /* Initialize all builtins in the AARCH64_BUILTIN_GENERAL group.  */
>  
>  void
> @@ -2288,6 +2314,8 @@ aarch64_general_init_builtins (void)
>      = aarch64_general_add_builtin ("__builtin_aarch64_chkfeat", ftype_chkfeat,
>  				   AARCH64_BUILTIN_CHKFEAT);
>  
> +  aarch64_init_gcs_builtins ();
> +
>    if (in_lto_p)
>      handle_arm_acle_h ();
>  }
> @@ -3367,6 +3395,43 @@ aarch64_expand_fpsr_fpcr_getter (enum insn_code icode, machine_mode mode,
>    return op.value;
>  }
>  
> +/* Expand GCS builtin EXP with code FCODE, putting the result
> +   int TARGET.  If IGNORE is true the return value is ignored.  */

into

This would need updating for the comment on patch 6, but otherwise
it looks good.

Thanks,
Richard

> +
> +rtx
> +aarch64_expand_gcs_builtin (tree exp, rtx target, int fcode, int ignore)
> +{
> +  if (fcode == AARCH64_BUILTIN_GCSPR)
> +    {
> +      expand_operand op;
> +      create_output_operand (&op, target, DImode);
> +      expand_insn (CODE_FOR_aarch64_load_gcspr, 1, &op);
> +      return op.value;
> +    }
> +  if (fcode == AARCH64_BUILTIN_GCSPOPM && ignore)
> +    {
> +      expand_insn (CODE_FOR_aarch64_gcspopm_xzr, 0, 0);
> +      return target;
> +    }
> +  if (fcode == AARCH64_BUILTIN_GCSPOPM)
> +    {
> +      expand_operand op;
> +      create_output_operand (&op, target, Pmode);
> +      expand_insn (CODE_FOR_aarch64_gcspopm, 1, &op);
> +      return op.value;
> +    }
> +  if (fcode == AARCH64_BUILTIN_GCSSS)
> +    {
> +      expand_operand ops[2];
> +      rtx op1 = expand_normal (CALL_EXPR_ARG (exp, 0));
> +      create_output_operand (&ops[0], target, Pmode);
> +      create_input_operand (&ops[1], op1, Pmode);
> +      expand_insn (CODE_FOR_aarch64_gcsss, 2, ops);
> +      return ops[0].value;
> +    }
> +  gcc_unreachable ();
> +}
> +
>  /* Expand an expression EXP that calls built-in function FCODE,
>     with result going to TARGET if that's convenient.  IGNORE is true
>     if the result of the builtin is ignored.  */
> @@ -3502,6 +3567,11 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
>  	emit_move_insn (target, x16_reg);
>  	return target;
>        }
> +
> +    case AARCH64_BUILTIN_GCSPR:
> +    case AARCH64_BUILTIN_GCSPOPM:
> +    case AARCH64_BUILTIN_GCSSS:
> +      return aarch64_expand_gcs_builtin (exp, target, fcode, ignore);
>      }
>  
>    if (fcode >= AARCH64_SIMD_BUILTIN_BASE && fcode <= AARCH64_SIMD_BUILTIN_MAX)