Hi Christophe,
> -----Original Message-----
> From: Christophe Lyon <christophe.l...@linaro.org>
> Sent: Thursday, July 6, 2023 4:21 PM
> To: Kyrylo Tkachov <kyrylo.tkac...@arm.com>
> Cc: gcc-patches@gcc.gnu.org; Richard Sandiford
> <richard.sandif...@arm.com>
> Subject: Re: [PATCH] arm: Fix MVE intrinsics support with LTO (PR
> target/110268)
>
>
>
> On Wed, 5 Jul 2023 at 19:07, Kyrylo Tkachov <kyrylo.tkac...@arm.com
> <mailto:kyrylo.tkac...@arm.com> > wrote:
>
>
> Hi Christophe,
>
> > -----Original Message-----
> > From: Christophe Lyon <christophe.l...@linaro.org
> <mailto:christophe.l...@linaro.org> >
> > Sent: Monday, June 26, 2023 4:03 PM
> > To: gcc-patches@gcc.gnu.org <mailto:gcc-patches@gcc.gnu.org> ;
> Kyrylo Tkachov <kyrylo.tkac...@arm.com
> <mailto:kyrylo.tkac...@arm.com> >;
> > Richard Sandiford <richard.sandif...@arm.com
> <mailto:richard.sandif...@arm.com> >
> > Cc: Christophe Lyon <christophe.l...@linaro.org
> <mailto:christophe.l...@linaro.org> >
> > Subject: [PATCH] arm: Fix MVE intrinsics support with LTO (PR
> target/110268)
> >
> > After the recent MVE intrinsics re-implementation, LTO stopped
> working
> > because the intrinsics would no longer be defined.
> >
> > The main part of the patch is simple and similar to what we do for
> > AArch64:
> > - call handle_arm_mve_h() from arm_init_mve_builtins to declare
> the
> > intrinsics when the compiler is in LTO mode
> > - actually implement arm_builtin_decl for MVE.
> >
> > It was just a bit tricky to handle
> __ARM_MVE_PRESERVE_USER_NAMESPACE:
> > its value in the user code cannot be guessed at LTO time, so we
> always
> > have to assume that it was not defined. The led to a few fixes in the
> > way we register MVE builtins as placeholders or not. Without this
> > patch, we would just omit some versions of the inttrinsics when
> > __ARM_MVE_PRESERVE_USER_NAMESPACE is true. In fact, like for
> the C/C++
> > placeholders, we need to always keep entries for all of them to
> ensure
> > that we have a consistent numbering scheme.
> >
> > 2023-06-26 Christophe Lyon <christophe.l...@linaro.org
> <mailto:christophe.l...@linaro.org> >
> >
> > PR target/110268
> > gcc/
> > * config/arm/arm-builtins.cc (arm_init_mve_builtins): Handle
> LTO.
> > (arm_builtin_decl): Hahndle MVE builtins.
> > * config/arm/arm-mve-builtins.cc (builtin_decl): New function.
> > (add_unique_function): Fix handling of
> > __ARM_MVE_PRESERVE_USER_NAMESPACE.
> > (add_overloaded_function): Likewise.
> > * config/arm/arm-protos.h (builtin_decl): New declaration.
> >
> > gcc/testsuite/
> > * gcc.target/arm/pr110268-1.c: New test.
> > * gcc.target/arm/pr110268-2.c: New test.
> > ---
> > gcc/config/arm/arm-builtins.cc | 11 +++-
> > gcc/config/arm/arm-mve-builtins.cc | 61 ++++++++++++----------
> -
> > gcc/config/arm/arm-protos.h | 1 +
> > gcc/testsuite/gcc.target/arm/pr110268-1.c | 11 ++++
> > gcc/testsuite/gcc.target/arm/pr110268-2.c | 22 ++++++++
> > 5 files changed, 76 insertions(+), 30 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.target/arm/pr110268-1.c
> > create mode 100644 gcc/testsuite/gcc.target/arm/pr110268-2.c
> >
> > diff --git a/gcc/config/arm/arm-builtins.cc b/gcc/config/arm/arm-
> builtins.cc
> > index 36365e40a5b..fca7dcaf565 100644
> > --- a/gcc/config/arm/arm-builtins.cc
> > +++ b/gcc/config/arm/arm-builtins.cc
> > @@ -1918,6 +1918,15 @@ arm_init_mve_builtins (void)
> > arm_builtin_datum *d = &mve_builtin_data[i];
> > arm_init_builtin (fcode, d, "__builtin_mve");
> > }
> > +
> > + if (in_lto_p)
> > + {
> > + arm_mve::handle_arm_mve_types_h ();
> > + /* Under LTO, we cannot know whether
> > + __ARM_MVE_PRESERVE_USER_NAMESPACE was defined, so
> assume
> > it
> > + was not. */
> > + arm_mve::handle_arm_mve_h (false);
> > + }
> > }
> >
> > /* Set up all the NEON builtins, even builtins for instructions that
> are not
> > @@ -2723,7 +2732,7 @@ arm_builtin_decl (unsigned code, bool
> initialize_p
> > ATTRIBUTE_UNUSED)
> > case ARM_BUILTIN_GENERAL:
> > return arm_general_builtin_decl (subcode);
> > case ARM_BUILTIN_MVE:
> > - return error_mark_node;
> > + return arm_mve::builtin_decl (subcode);
> > default:
> > gcc_unreachable ();
> > }
> > diff --git a/gcc/config/arm/arm-mve-builtins.cc
> b/gcc/config/arm/arm-mve-
> > builtins.cc
> > index 7033e41a571..e9a12f27411 100644
> > --- a/gcc/config/arm/arm-mve-builtins.cc
> > +++ b/gcc/config/arm/arm-mve-builtins.cc
> > @@ -493,6 +493,16 @@ handle_arm_mve_h (bool
> > preserve_user_namespace)
> > preserve_user_namespace);
> > }
> >
> > +/* Return the function decl with SVE function subcode CODE, or
> > error_mark_node
> > + if no such function exists. */
> > +tree
> > +builtin_decl (unsigned int code)
> > +{
> > + if (code >= vec_safe_length (registered_functions))
> > + return error_mark_node;
> > + return (*registered_functions)[code]->decl;
> > +}
> > +
> > /* Return true if CANDIDATE is equivalent to MODEL_TYPE for
> overloading
> > purposes. */
> > static bool
> > @@ -849,7 +859,6 @@ function_builder::add_function (const
> > function_instance &instance,
> > ? integer_zero_node
> > : simulate_builtin_function_decl (input_location, name, fntype,
> > code, NULL, attrs);
> > -
> > registered_function &rfn = *ggc_alloc <registered_function> ();
> > rfn.instance = instance;
> > rfn.decl = decl;
> > @@ -889,15 +898,12 @@ function_builder::add_unique_function
> (const
> > function_instance &instance,
> > gcc_assert (!*rfn_slot);
> > *rfn_slot = &rfn;
> >
> > - /* Also add the non-prefixed non-overloaded function, if the user
> > namespace
> > - does not need to be preserved. */
> > - if (!preserve_user_namespace)
> > - {
> > - char *noprefix_name = get_name (instance, false, false);
> > - tree attrs = get_attributes (instance);
> > - add_function (instance, noprefix_name, fntype, attrs,
> requires_float,
> > - false, false);
> > - }
> > + /* Also add the non-prefixed non-overloaded function, as
> placeholder
> > + if the user namespace does not need to be preserved. */
> > + char *noprefix_name = get_name (instance, false, false);
> > + attrs = get_attributes (instance);
> > + add_function (instance, noprefix_name, fntype, attrs,
> requires_float,
> > + false, preserve_user_namespace);
> >
> > /* Also add the function under its overloaded alias, if we want
> > a separate decl for each instance of an overloaded function. */
> > @@ -905,20 +911,17 @@ function_builder::add_unique_function
> (const
> > function_instance &instance,
> > if (strcmp (name, overload_name) != 0)
> > {
> > /* Attribute lists shouldn't be shared. */
> > - tree attrs = get_attributes (instance);
> > + attrs = get_attributes (instance);
> > bool placeholder_p = !(m_direct_overloads ||
> force_direct_overloads);
> > add_function (instance, overload_name, fntype, attrs,
> > requires_float, false, placeholder_p);
> >
> > - /* Also add the non-prefixed overloaded function, if the user
> namespace
> > - does not need to be preserved. */
> > - if (!preserve_user_namespace)
> > - {
> > - char *noprefix_overload_name = get_name (instance, false,
> true);
> > - tree attrs = get_attributes (instance);
> > - add_function (instance, noprefix_overload_name, fntype, attrs,
> > - requires_float, false, placeholder_p);
> > - }
> > + /* Also add the non-prefixed overloaded function, as
> placeholder
> > + if the user namespace does not need to be preserved. */
> > + char *noprefix_overload_name = get_name (instance, false,
> true);
> > + attrs = get_attributes (instance);
> > + add_function (instance, noprefix_overload_name, fntype, attrs,
> > + requires_float, false, preserve_user_namespace ||
> > placeholder_p);
> > }
> >
> > obstack_free (&m_string_obstack, name);
> > @@ -948,15 +951,15 @@
> function_builder::add_overloaded_function (const
> > function_instance &instance,
> > = add_function (instance, name, m_overload_type, NULL_TREE,
> > requires_float, true, m_direct_overloads);
> > m_overload_names.put (name, &rfn);
> > - if (!preserve_user_namespace)
> > - {
> > - char *noprefix_name = get_name (instance, false, true);
> > - registered_function &noprefix_rfn
> > - = add_function (instance, noprefix_name, m_overload_type,
> > - NULL_TREE, requires_float, true,
> > - m_direct_overloads);
> > - m_overload_names.put (noprefix_name, &noprefix_rfn);
> > - }
> > +
> > + /* Also add the non-prefixed function, as placeholder if the
> > + user namespace does not need to be preserved. */
> > + char *noprefix_name = get_name (instance, false, true);
> > + registered_function &noprefix_rfn
> > + = add_function (instance, noprefix_name, m_overload_type,
> > + NULL_TREE, requires_float, true,
> > + preserve_user_namespace || m_direct_overloads);
> > + m_overload_names.put (noprefix_name, &noprefix_rfn);
> > }
> > }
> >
> > diff --git a/gcc/config/arm/arm-protos.h b/gcc/config/arm/arm-
> protos.h
> > index 7d73c66a15d..6186921011e 100644
> > --- a/gcc/config/arm/arm-protos.h
> > +++ b/gcc/config/arm/arm-protos.h
> > @@ -232,6 +232,7 @@ const unsigned int ARM_BUILTIN_CLASS = (1
> <<
> > ARM_BUILTIN_SHIFT) - 1;
> > namespace arm_mve {
> > void handle_arm_mve_types_h ();
> > void handle_arm_mve_h (bool);
> > + tree builtin_decl (unsigned);
> > tree resolve_overloaded_builtin (location_t, unsigned int,
> > vec<tree, va_gc> *);
> > bool check_builtin_call (location_t, vec<location_t>, unsigned int,
> > diff --git a/gcc/testsuite/gcc.target/arm/pr110268-1.c
> > b/gcc/testsuite/gcc.target/arm/pr110268-1.c
> > new file mode 100644
> > index 00000000000..d133011343c
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/arm/pr110268-1.c
> > @@ -0,0 +1,11 @@
> > +/* { dg-do link } */
> > +/* { dg-require-effective-target arm_v8_1m_mve_ok } */
> > +/* { dg-add-options arm_v8_1m_mve } */
> > +/* { dg-additional-options "-O2 -flto -specs=rdimon.specs" } */
>
> IIRC rdimon.specs is a thing coming out of libgloss/newlib so may not
> be valid for some other libcs?
>
>
>
> Ha right. In my mind MVE implies arm-eabi target, which implies newlib so I
> overlooked this.
>
>
> Would it make sense to also require a newlib effective target?
>
>
> I didn't know about this one ;-)
>
> Revisiting this, I realized that -specs=rdimon.specs does not belong here, in
> fact I updated my dejagnu setup to add this (required) option automagically
> behind the scenes (via set_board_info ldflags), thus removing it from dg-
> additional-options.
>
> In fact there's no reason to require newlib, we just need to be able to link.
> In
> principle we could have linux+glibc on an MVE target.
> Unfortunately, it seems there's no such effective-target yet, the closest
> being
> arm_arch_v8_1m_main_multilib.
> However this one also implies being able to execute the resulting binary,
> which may not be possible (actually it isn't in my current setup due to a
> bug/feature in qemu).
>
> So I hacked additions to target-supports.exp, to add:
> check_effective_target_arm_arch_FUNC_link
>
> check_effective_target_FUNC_link
>
> to our existing list, and they call "check_no_compiler_messages ...
> executable" instead of check_runtime.
>
> And this means the testcases now have:
> /* { dg-require-effective-target arm_arch_v8_1m_main_link } */ /* Make sure
> we have suitable multilibs to link successfully. */
>
> /* { dg-require-effective-target arm_v8_1m_mve_ok } */
>
>
> Ideally we should perhaps also increase the list of effective targets that
> cover
> MVE, such that we also have "_multilib" etc but that seems a bit overkill?
> OTOH, the discrepancy above might be confusing (arm_arch_v8_1m_main vs
> arm_v8_1m_mve).
>
> So.... are you OK with a separate patch to add
> check_effective_target_arm_arch_FUNC_link and
> check_effective_target_FUNC_link and this one updated with the dg-require-
> effective-target as above?
Yeah, I think that's a good solution.
>
> Too bad things are so complicated with the many flavours we have ;-)
Yeah, it trips up almost every new addition to the testsuite these days ☹ we'll
need to sit down and think about simplifying this all at some point.
Thanks,
Kyrill
>
> Thanks,
>
> Christophe
>
>
> Ok otherwise.
> Thanks,
> Kyrill
>
> > +
> > +#include <arm_mve.h>
> > +
> > +int main(int argc, char* argv[])
> > +{
> > + return vaddvq(__arm_vdupq_n_s8 (argc));
> > +}
> > diff --git a/gcc/testsuite/gcc.target/arm/pr110268-2.c
> > b/gcc/testsuite/gcc.target/arm/pr110268-2.c
> > new file mode 100644
> > index 00000000000..ad03fb37793
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/arm/pr110268-2.c
> > @@ -0,0 +1,22 @@
> > +/* { dg-do link } */
> > +/* { dg-require-effective-target arm_v8_1m_mve_ok } */
> > +/* { dg-add-options arm_v8_1m_mve } */
> > +/* { dg-additional-options "-O2 -flto -specs=rdimon.specs" } */
> > +
> > +/* Check MVE intrinsics with LTO with
> > __ARM_MVE_PRESERVE_USER_NAMESPACE and a
> > + user-overridden intrinsic. */
> > +
> > +#define __ARM_MVE_PRESERVE_USER_NAMESPACE
> > +#include <arm_mve.h>
> > +
> > +int global_int;
> > +int32_t vaddvq(int8x16_t x)
> > +{
> > + return global_int + __arm_vgetq_lane_s8 (x, 0);
> > +}
> > +
> > +int main(int argc, char* argv[])
> > +{
> > + global_int = argc;
> > + return vaddvq(__arm_vdupq_n_s8 (argc));
> > +}
> > --
> > 2.34.1
>
>
