Alex Coplan <alex.cop...@arm.com> writes:
> Hi all,
>
> As discussed in the PR, we currently have two different numbering
> schemes for SVE builtins: one for C, and one for C++. This is
> problematic for LTO, where we end up getting confused about which
> intrinsic we're talking about. This patch inserts placeholders into the
> registered_functions vector to ensure that there is a consistent
> numbering scheme for both C and C++.
>
> Initially I tried using a null decl for these placeholders, but this
> trips up some validation when the builtin trees are streamed into lto1,
> so I ended up building dummy FUNCTION_DECLs as placeholders.
>
> To get better test coverage here, I'm wondering if we could make some of
> the existing ACLE tests also run with LTO? Perhaps as a follow-on patch?
> For now I've just added the specific testcase from the PR.
>
> Bootstrapped and regtested on aarch64-linux-gnu, OK for trunk?
OK, thanks. I think we should backport this to GCC 10, but as Richi says,
that would need a bump in lto-streamer.h:LTO_minor_version.
Thanks,
Richard
>
> Thanks,
> Alex
>
> ---
>
> gcc/ChangeLog:
>
> PR target/99216
> * config/aarch64/aarch64-sve-builtins.cc
> (function_builder::add_function): Add placeholder_p argument, build
> placeholder decls if this is set.
> (function_builder::add_unique_function): Instead of conditionally adding
> direct overloads, unconditionally add either a direct overload or a
> placeholder.
> (function_builder::add_overloaded_function): Set placeholder_p if we're
> using C++ overloads.
> (function_builder::add_overloaded_functions): Don't return early for
> m_direct_overloads: we need to add placeholders.
> * config/aarch64/aarch64-sve-builtins.h
> (function_builder::add_function): Add placeholder_p argument.
>
> gcc/testsuite/ChangeLog:
>
> PR target/99216
> * g++.target/aarch64/sve/pr99216.C: New test.
>
> diff --git a/gcc/config/aarch64/aarch64-sve-builtins.cc
> b/gcc/config/aarch64/aarch64-sve-builtins.cc
> index 25612d2ea52..c0ba352599c 100644
> --- a/gcc/config/aarch64/aarch64-sve-builtins.cc
> +++ b/gcc/config/aarch64/aarch64-sve-builtins.cc
> @@ -999,12 +999,25 @@ registered_function &
> function_builder::add_function (const function_instance &instance,
> const char *name, tree fntype, tree attrs,
> uint64_t required_extensions,
> - bool overloaded_p)
> + bool overloaded_p,
> + bool placeholder_p)
> {
> unsigned int code = vec_safe_length (registered_functions);
> code = (code << AARCH64_BUILTIN_SHIFT) | AARCH64_BUILTIN_SVE;
> - tree decl = simulate_builtin_function_decl (input_location, name, fntype,
> - code, NULL, attrs);
> +
> + /* We need to be able to generate placeholders to enusre that we have a
> + consistent numbering scheme for function codes between the C and C++
> + frontends, so that everything ties up in LTO.
> +
> + The placeholder needs to be non-NULL and some node other than
> + error_mark_node to pass validation when the builtin is streamed in to
> lto1.
> +
> + It's also convenient if the placeholder can store the name, so build a
> + FUNCTION_DECL, but don't register it with the frontend. */
> + tree decl = placeholder_p
> + ? build_decl (input_location, FUNCTION_DECL, get_identifier (name),
> fntype)
> + : simulate_builtin_function_decl (input_location, name, fntype,
> + code, NULL, attrs);
>
> registered_function &rfn = *ggc_alloc <registered_function> ();
> rfn.instance = instance;
> @@ -1036,7 +1049,7 @@ function_builder::add_unique_function (const
> function_instance &instance,
> argument_types.address ());
> tree attrs = get_attributes (instance);
> registered_function &rfn = add_function (instance, name, fntype, attrs,
> - required_extensions, false);
> + required_extensions, false, false);
>
> /* Enter the function into the hash table. */
> hashval_t hash = instance.hash ();
> @@ -1047,16 +1060,14 @@ function_builder::add_unique_function (const
> function_instance &instance,
>
> /* Also add the function under its overloaded alias, if we want
> a separate decl for each instance of an overloaded function. */
> - if (m_direct_overloads || force_direct_overloads)
> + char *overload_name = get_name (instance, true);
> + if (strcmp (name, overload_name) != 0)
> {
> - char *overload_name = get_name (instance, true);
> - if (strcmp (name, overload_name) != 0)
> - {
> - /* Attribute lists shouldn't be shared. */
> - tree attrs = get_attributes (instance);
> - add_function (instance, overload_name, fntype, attrs,
> - required_extensions, false);
> - }
> + /* Attribute lists shouldn't be shared. */
> + tree attrs = get_attributes (instance);
> + bool placeholder_p = !(m_direct_overloads || force_direct_overloads);
> + add_function (instance, overload_name, fntype, attrs,
> + required_extensions, false, placeholder_p);
> }
>
> obstack_free (&m_string_obstack, name);
> @@ -1084,7 +1095,7 @@ function_builder::add_overloaded_function (const
> function_instance &instance,
> {
> registered_function &rfn
> = add_function (instance, name, m_overload_type, NULL_TREE,
> - required_extensions, true);
> + required_extensions, true, m_direct_overloads);
> const char *permanent_name = IDENTIFIER_POINTER (DECL_NAME (rfn.decl));
> m_overload_names.put (permanent_name, &rfn);
> }
> @@ -1098,9 +1109,6 @@ void
> function_builder::add_overloaded_functions (const function_group_info &group,
> mode_suffix_index mode)
> {
> - if (m_direct_overloads)
> - return;
> -
> unsigned int explicit_type0 = (*group.shape)->explicit_type_suffix_p (0);
> unsigned int explicit_type1 = (*group.shape)->explicit_type_suffix_p (1);
> for (unsigned int pi = 0; group.preds[pi] != NUM_PREDS; ++pi)
> diff --git a/gcc/config/aarch64/aarch64-sve-builtins.h
> b/gcc/config/aarch64/aarch64-sve-builtins.h
> index 620e18841b2..b701f90ac1a 100644
> --- a/gcc/config/aarch64/aarch64-sve-builtins.h
> +++ b/gcc/config/aarch64/aarch64-sve-builtins.h
> @@ -337,7 +337,8 @@ private:
> tree get_attributes (const function_instance &);
>
> registered_function &add_function (const function_instance &,
> - const char *, tree, tree, uint64_t, bool);
> + const char *, tree, tree,
> + uint64_t, bool, bool);
>
> /* The function type to use for functions that are resolved by
> function_resolver. */
> diff --git a/gcc/testsuite/g++.target/aarch64/sve/pr99216.C
> b/gcc/testsuite/g++.target/aarch64/sve/pr99216.C
> new file mode 100644
> index 00000000000..61a58a7fcf4
> --- /dev/null
> +++ b/gcc/testsuite/g++.target/aarch64/sve/pr99216.C
> @@ -0,0 +1,5 @@
> +/* { dg-do link { target aarch64_asm_sve_ok } } */
> +/* { dg-additional-options "-flto" } */
> +#include <arm_sve.h>
> +bool a;
> +int main() { a = svaddv(svptrue_b8(), svdup_s8(0)); }
