Alice Carlotti <alice.carlo...@arm.com> writes:
> This applies to the sysreg read/write intrinsics __arm_[wr]sr*. It does
> not depend on changes to Binutils, because GCC converts recognised
> sysreg names to an encoding based form, which is already ungated in Binutils.
>
> We have, however, agreed to make an equivalent change in Binutils (which
> would then disable feature gating for sysreg accesses in inline
> assembly), but this has not yet been posted upstream.
>
> In the future we may introduce a new flag to renable some checking,
> but these checks could not be comprehensive because many system
> registers depend on architecture features that don't have corresponding
> GCC/GAS --march options. This would also depend on addressing numerous
> inconsistencies in the existing list of sysreg feature dependencies.
>
> ---
>
> Ok for master now? And how about backporting to gcc 14? I do recognise that
> this is late in stage 4, sorry - it slipped through the gaps of being
> Binutils-adjacent work with a different deadline.
OK for trunk and backports. I'm disappointed that I didn't notice
the lack of dg-error tests for the code being removed.
Thanks,
Richard
>
> Thanks,
> Alice
>
>
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64.cc
> (aarch64_valid_sysreg_name_p): Remove feature check.
> (aarch64_retrieve_sysreg): Ditto.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/aarch64/acle/rwsr-ungated.c: New test.
>
>
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index
> 4e801146c60a52c7ef6f8c0f92b1b922e729c234..433ec975d7e4e9d7130fe49eac37f4ebfb880416
> 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -31073,8 +31073,6 @@ aarch64_valid_sysreg_name_p (const char *regname)
> const sysreg_t *sysreg = aarch64_lookup_sysreg_map (regname);
> if (sysreg == NULL)
> return aarch64_is_implem_def_reg (regname);
> - if (sysreg->arch_reqs)
> - return bool (aarch64_isa_flags & sysreg->arch_reqs);
> return true;
> }
>
> @@ -31098,8 +31096,6 @@ aarch64_retrieve_sysreg (const char *regname, bool
> write_p, bool is128op)
> if ((write_p && (sysreg->properties & F_REG_READ))
> || (!write_p && (sysreg->properties & F_REG_WRITE)))
> return NULL;
> - if ((~aarch64_isa_flags & sysreg->arch_reqs) != 0)
> - return NULL;
> return sysreg->encoding;
> }
>
> diff --git a/gcc/testsuite/gcc.target/aarch64/acle/rwsr-ungated.c
> b/gcc/testsuite/gcc.target/aarch64/acle/rwsr-ungated.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..d67a42673733cdb128fd62d465fa122037ae531d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/acle/rwsr-ungated.c
> @@ -0,0 +1,13 @@
> +/* Test that __arm_[r,w]sr intrinsics aren't gated (by default). */
> +
> +/* { dg-do compile } */
> +/* { dg-options "-march=armv8-a" } */
> +
> +#include <arm_acle.h>
> +
> +uint64_t
> +foo (uint64_t a)
> +{
> + __arm_wsr64 ("zcr_el1", a);
> + return __arm_rsr64 ("smcr_el1");
> +}
