On Sat, Dec 9, 2023 at 3:09 AM Alexandre Oliva <[email protected]> wrote:
>
> On Dec 7, 2023, Alexandre Oliva <[email protected]> wrote:
>
> > Thanks for raising the issue. Maybe there should be at least a comment
> > there, and perhaps some asserts to check that pointer and reference
> > types don't make to indirect_parms.
>
> Document why attribute access doesn't need the same treatment as fn
> spec, and check that the assumption behind it holds.
>
> Regstrapped on x86_64-linux-gnu. Ok to install?
OK
>
> for gcc/ChangeLog
>
> * ipa-strub.cc (pass_ipa_strub::execute): Check that we don't
> add indirection to pointer parameters, and document attribute
> access non-interactions.
> ---
> gcc/ipa-strub.cc | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/ipa-strub.cc b/gcc/ipa-strub.cc
> index 2afb7a455751d..8ec6824e8a802 100644
> --- a/gcc/ipa-strub.cc
> +++ b/gcc/ipa-strub.cc
> @@ -2889,6 +2889,13 @@ pass_ipa_strub::execute (function *)
> && (tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (nparm)))
> <= 4 * UNITS_PER_WORD))))
> {
> + /* No point in indirecting pointer types. Presumably they
> + won't ever pass the size-based test above, but check the
> + assumption here, because getting this wrong would mess
> + with attribute access and possibly others. We deal with
> + fn spec below. */
> + gcc_checking_assert (!POINTER_TYPE_P (TREE_TYPE (nparm)));
> +
> indirect_nparms.add (nparm);
>
> /* ??? Is there any case in which it is not safe to suggest the
> parms
> @@ -2976,7 +2983,9 @@ pass_ipa_strub::execute (function *)
> }
> }
>
> - /* ??? Maybe we could adjust it instead. */
> + /* ??? Maybe we could adjust it instead. Note we don't need
> + to mess with attribute access: pointer-typed parameters are
> + not modified, so they can remain unchanged. */
> if (drop_fnspec)
> remove_named_attribute_unsharing ("fn spec",
> &TYPE_ATTRIBUTES (nftype));
>
>
> --
> Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
> Free Software Activist GNU Toolchain Engineer
> More tolerance and less prejudice are key for inclusion and diversity
> Excluding neuro-others for not behaving ""normal"" is *not* inclusive
