> On 31 Oct 2024, at 14:23, Yury Khrustalev <yury.khrusta...@arm.com> wrote:
>
> From: Szabolcs Nagy <szabolcs.n...@arm.com>
>
> Builtin for chkfeat: the input argument is used to initialize x16 then
> execute chkfeat and return the updated x16.
>
> Note: ACLE __chkfeat(x) plans to flip the bits to be more intuitive
> (xor the input to output), but for the builtin that seems unnecessary
> complication.
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64-builtins.cc (enum aarch64_builtins):
> Define AARCH64_BUILTIN_CHKFEAT.
> (aarch64_general_init_builtins): Handle chkfeat.
> (aarch64_general_expand_builtin): Handle chkfeat.
> Co-authored-by: Richard Sandiford <richard.sandif...@arm.com>
> ---
> gcc/config/aarch64/aarch64-builtins.cc | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/gcc/config/aarch64/aarch64-builtins.cc
> b/gcc/config/aarch64/aarch64-builtins.cc
> index 86d96e47f01..55506530ee4 100644
> --- a/gcc/config/aarch64/aarch64-builtins.cc
> +++ b/gcc/config/aarch64/aarch64-builtins.cc
> @@ -884,6 +884,8 @@ enum aarch64_builtins
> AARCH64_PLDX,
> AARCH64_PLI,
> AARCH64_PLIX,
> + /* Armv8.9-A / Armv9.4-A builtins. */
> + AARCH64_BUILTIN_CHKFEAT,
> AARCH64_BUILTIN_MAX
> };
>
> @@ -2294,6 +2296,12 @@ aarch64_general_init_builtins (void)
> if (!TARGET_ILP32)
> aarch64_init_pauth_hint_builtins ();
>
> + tree ftype_chkfeat
> + = build_function_type_list (uint64_type_node, uint64_type_node, NULL);
> + aarch64_builtin_decls[AARCH64_BUILTIN_CHKFEAT]
> + = aarch64_general_add_builtin ("__builtin_aarch64_chkfeat",
> ftype_chkfeat,
> + AARCH64_BUILTIN_CHKFEAT);
> +
Is the builtin intended to be used just to implement the ACLE __chkfeat ()
intrinsic in the future or is it expected to be used directly by users?
If so, it should be documented somehow. I also note that Clang seems to have a
similar builtin with a deviating name “__builtin_arm_chkfeat”.
This is fine, of course, if the user is only expected to use the arm_acle.h
intrinsic. Do you intend to implement that in this cycle as well?
Thanks,
Kyrill
> if (in_lto_p)
> handle_arm_acle_h ();
> }
> @@ -3498,6 +3506,15 @@ aarch64_general_expand_builtin (unsigned int fcode,
> tree exp, rtx target,
> case AARCH64_PLIX:
> aarch64_expand_prefetch_builtin (exp, fcode);
> return target;
> +
> + case AARCH64_BUILTIN_CHKFEAT:
> + {
> + rtx x16_reg = gen_rtx_REG (DImode, R16_REGNUM);
> + op0 = expand_normal (CALL_EXPR_ARG (exp, 0));
> + emit_move_insn (x16_reg, op0);
> + expand_insn (CODE_FOR_aarch64_chkfeat, 0, 0);
> + return copy_to_reg (x16_reg);
> + }
> }
>
> if (fcode >= AARCH64_SIMD_BUILTIN_BASE && fcode <= AARCH64_SIMD_BUILTIN_MAX)
> --
> 2.39.5
>
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