> On 8 Oct 2026, at 16:25, Alice Carlotti <[email protected]> wrote:
>
> On Thu, Sep 03, 2026 at 04:21:32AM +0100, Alice Carlotti wrote:
>> Thanks - I've added this missing line:
>> (svpfalse_impl::fold): Handle svcount_t.
>>
>> and pushed it to master. I'll also push it to the affected branches after
>> waiting a bit.
>>
>> Alice
>
>
> I've backported this to gcc-16 and gcc-15 (with the ChangeLog tweaked to
> mention aarch64-sve-builtins.cc instead). For gcc-14, a couple more changes
> are needed:
>
> - The folding for svcount_t uses fold_call_to, which was added in
> r15-5957-g5289540ed58e42. I've dropped that change, so it now punts for
> svcount_t (which is closer to the existing behaviour).
> - The intrinsics were originally added for sme2 in gcc-14, but the tests use
> sve2p1, which was added in gcc-15. I've dropped the tests here.
>
> Is this ok for the gcc-14 backport?
>
Ok.
Thanks,
Kyrill
> ---
>
> This fixes an ICE that occurred when trying to fold svwhilelt and
> svwhilele predicate-as-counter builtins as if they were
> predicate-as-mask builtins.
>
> gcc/ChangeLog:
>
> PR target/126096
> * config/aarch64/aarch64-sve-builtins.cc
> (gimple_folder::fold_to_pfalse): Punt for svcount_t.
> * config/aarch64/aarch64-sve-builtins-base.cc
> (svpfalse_impl::fold): Defer svcount_t check.
> (svwhilelx_impl::fold_type): Punt for svcount_t.
>
>
> diff --git a/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> index
> 05ef1c1dcb363a4c0bfdc9c76378f9db47899448..b76cb5ecaa93c471792695bd5664677f41fc88a5
> 100644
> --- a/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> +++ b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> @@ -2041,10 +2041,7 @@ public:
> gimple *
> fold (gimple_folder &f) const override
> {
> - if (f.type_suffix (0).tclass == TYPE_bool)
> - return f.fold_to_pfalse ();
> -
> - return nullptr;
> + return f.fold_to_pfalse ();
> }
>
> rtx
> @@ -2907,6 +2904,10 @@ public:
> if (m_eq_p ? known_gt (arg0, arg1) : known_ge (arg0, arg1))
> return f.fold_to_pfalse ();
>
> + /* Punt if we are trying to fold a predicate-as-counter builtin. */
> + if (f.type_suffix (0).tclass == TYPE_count)
> + return NULL;
> +
> /* Punt if we can't tell at compile time whether the result
> is all-false. */
> if (m_eq_p ? maybe_gt (arg0, arg1) : maybe_ge (arg0, arg1))
> diff --git a/gcc/config/aarch64/aarch64-sve-builtins.cc
> b/gcc/config/aarch64/aarch64-sve-builtins.cc
> index
> 6416c18e15e5e6409bd7d294bd3904909591d97b..363b05ac02beed19d01f5c4b87adc8a2c4d78ea1
> 100644
> --- a/gcc/config/aarch64/aarch64-sve-builtins.cc
> +++ b/gcc/config/aarch64/aarch64-sve-builtins.cc
> @@ -3565,7 +3565,16 @@ gimple_folder::fold_to_ptrue ()
> gimple *
> gimple_folder::fold_to_pfalse ()
> {
> - return gimple_build_assign (lhs, build_zero_cst (TREE_TYPE (lhs)));
> + if (type_suffix (0).tclass == TYPE_bool)
> + return gimple_build_assign (lhs, build_zero_cst (TREE_TYPE (lhs)));
> +
> + if (type_suffix (0).tclass == TYPE_count)
> + {
> + tree svbool_type = abi_vector_types[VECTOR_TYPE_svbool_t];
> + return fold_call_to (build_zero_cst (svbool_type));
> + }
> +
> + return NULL;
> }
>
> /* Fold an operation to a constant predicate in which the first VL
