A couple of va_gc_atomic tweaks
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Commit Message
The only current user of va_gc_atomic is Ada's:
vec<Entity_Id, va_gc_atomic>
It uses the generic gt_pch_nx routines (with gt_pch_nx being the
“note pointers” hooks), such as:
template<typename T, typename A>
void
gt_pch_nx (vec<T, A, vl_embed> *v)
{
extern void gt_pch_nx (T &);
for (unsigned i = 0; i < v->length (); i++)
gt_pch_nx ((*v)[i]);
}
It then defines gt_pch_nx routines for Entity_Id &.
The problem is that if we wanted to take the same approach for
an array of unsigned ints, we'd need to define:
inline void gt_pch_nx (unsigned int &) { }
which would then be ambiguous with:
inline void gt_pch_nx (unsigned int) { }
The point of va_gc_atomic is that the elements don't need to be GCed,
and so we have:
template<typename T>
void
gt_ggc_mx (vec<T, va_gc_atomic, vl_embed> *v ATTRIBUTE_UNUSED)
{
/* Nothing to do. Vectors of atomic types wrt GC do not need to
be traversed. */
}
I think it's therefore reasonable to assume that no pointers will
need to be processed for PCH either.
The patch also relaxes the array_slice constructor for vec<T, va_gc> *
so that it handles all embedded vectors.
Bootstrapped & regression-tested on aarch64-linux-gnu (all languages).
OK to install?
Richard
gcc/
* vec.h (gt_pch_nx): Add overloads for va_gc_atomic.
(array_slice): Relax va_gc constructor to handle all vectors
with a vl_embed layout.
gcc/ada/
* gcc-interface/decl.cc (gt_pch_nx): Remove overloads for Entity_Id.
---
gcc/ada/gcc-interface/decl.cc | 11 -----------
gcc/vec.h | 22 ++++++++++++++++++----
2 files changed, 18 insertions(+), 15 deletions(-)
Comments
On Wed, Jun 28, 2023 at 11:37 PM Richard Sandiford via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The only current user of va_gc_atomic is Ada's:
>
> vec<Entity_Id, va_gc_atomic>
>
> It uses the generic gt_pch_nx routines (with gt_pch_nx being the
> “note pointers” hooks), such as:
>
> template<typename T, typename A>
> void
> gt_pch_nx (vec<T, A, vl_embed> *v)
> {
> extern void gt_pch_nx (T &);
> for (unsigned i = 0; i < v->length (); i++)
> gt_pch_nx ((*v)[i]);
> }
>
> It then defines gt_pch_nx routines for Entity_Id &.
>
> The problem is that if we wanted to take the same approach for
> an array of unsigned ints, we'd need to define:
>
> inline void gt_pch_nx (unsigned int &) { }
>
> which would then be ambiguous with:
>
> inline void gt_pch_nx (unsigned int) { }
>
> The point of va_gc_atomic is that the elements don't need to be GCed,
> and so we have:
>
> template<typename T>
> void
> gt_ggc_mx (vec<T, va_gc_atomic, vl_embed> *v ATTRIBUTE_UNUSED)
> {
> /* Nothing to do. Vectors of atomic types wrt GC do not need to
> be traversed. */
> }
>
> I think it's therefore reasonable to assume that no pointers will
> need to be processed for PCH either.
>
> The patch also relaxes the array_slice constructor for vec<T, va_gc> *
> so that it handles all embedded vectors.
>
> Bootstrapped & regression-tested on aarch64-linux-gnu (all languages).
> OK to install?
OK.
Thanks,
Richard.
> Richard
>
>
> gcc/
> * vec.h (gt_pch_nx): Add overloads for va_gc_atomic.
> (array_slice): Relax va_gc constructor to handle all vectors
> with a vl_embed layout.
>
> gcc/ada/
> * gcc-interface/decl.cc (gt_pch_nx): Remove overloads for Entity_Id.
> ---
> gcc/ada/gcc-interface/decl.cc | 11 -----------
> gcc/vec.h | 22 ++++++++++++++++++----
> 2 files changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/gcc/ada/gcc-interface/decl.cc b/gcc/ada/gcc-interface/decl.cc
> index 494b24e2111..ee913a017d2 100644
> --- a/gcc/ada/gcc-interface/decl.cc
> +++ b/gcc/ada/gcc-interface/decl.cc
> @@ -163,17 +163,6 @@ struct GTY((for_user)) tree_entity_vec_map
> vec<Entity_Id, va_gc_atomic> *to;
> };
>
> -void
> -gt_pch_nx (Entity_Id &)
> -{
> -}
> -
> -void
> -gt_pch_nx (Entity_Id *x, gt_pointer_operator op, void *cookie)
> -{
> - op (x, NULL, cookie);
> -}
> -
> struct dummy_type_hasher : ggc_cache_ptr_hash<tree_entity_vec_map>
> {
> static inline hashval_t
> diff --git a/gcc/vec.h b/gcc/vec.h
> index 36918915701..6f7b0487eb6 100644
> --- a/gcc/vec.h
> +++ b/gcc/vec.h
> @@ -1390,6 +1390,13 @@ gt_pch_nx (vec<T, A, vl_embed> *v)
> gt_pch_nx ((*v)[i]);
> }
>
> +template<typename T>
> +void
> +gt_pch_nx (vec<T, va_gc_atomic, vl_embed> *)
> +{
> + /* No pointers to note. */
> +}
> +
> template<typename T, typename A>
> void
> gt_pch_nx (vec<T *, A, vl_embed> *v, gt_pointer_operator op, void *cookie)
> @@ -1407,6 +1414,13 @@ gt_pch_nx (vec<T, A, vl_embed> *v, gt_pointer_operator op, void *cookie)
> gt_pch_nx (&((*v)[i]), op, cookie);
> }
>
> +template<typename T>
> +void
> +gt_pch_nx (vec<T, va_gc_atomic, vl_embed> *, gt_pointer_operator, void *)
> +{
> + /* No pointers to note. */
> +}
> +
>
> /* Space efficient vector. These vectors can grow dynamically and are
> allocated together with their control data. They are suited to be
> @@ -2286,12 +2300,12 @@ public:
> array_slice (vec<OtherT> &v)
> : m_base (v.address ()), m_size (v.length ()) {}
>
> - template<typename OtherT>
> - array_slice (const vec<OtherT, va_gc> *v)
> + template<typename OtherT, typename A>
> + array_slice (const vec<OtherT, A, vl_embed> *v)
> : m_base (v ? v->address () : nullptr), m_size (v ? v->length () : 0) {}
>
> - template<typename OtherT>
> - array_slice (vec<OtherT, va_gc> *v)
> + template<typename OtherT, typename A>
> + array_slice (vec<OtherT, A, vl_embed> *v)
> : m_base (v ? v->address () : nullptr), m_size (v ? v->length () : 0) {}
>
> iterator begin () { return m_base; }
> --
> 2.25.1
>
@@ -163,17 +163,6 @@ struct GTY((for_user)) tree_entity_vec_map
vec<Entity_Id, va_gc_atomic> *to;
};
-void
-gt_pch_nx (Entity_Id &)
-{
-}
-
-void
-gt_pch_nx (Entity_Id *x, gt_pointer_operator op, void *cookie)
-{
- op (x, NULL, cookie);
-}
-
struct dummy_type_hasher : ggc_cache_ptr_hash<tree_entity_vec_map>
{
static inline hashval_t
@@ -1390,6 +1390,13 @@ gt_pch_nx (vec<T, A, vl_embed> *v)
gt_pch_nx ((*v)[i]);
}
+template<typename T>
+void
+gt_pch_nx (vec<T, va_gc_atomic, vl_embed> *)
+{
+ /* No pointers to note. */
+}
+
template<typename T, typename A>
void
gt_pch_nx (vec<T *, A, vl_embed> *v, gt_pointer_operator op, void *cookie)
@@ -1407,6 +1414,13 @@ gt_pch_nx (vec<T, A, vl_embed> *v, gt_pointer_operator op, void *cookie)
gt_pch_nx (&((*v)[i]), op, cookie);
}
+template<typename T>
+void
+gt_pch_nx (vec<T, va_gc_atomic, vl_embed> *, gt_pointer_operator, void *)
+{
+ /* No pointers to note. */
+}
+
/* Space efficient vector. These vectors can grow dynamically and are
allocated together with their control data. They are suited to be
@@ -2286,12 +2300,12 @@ public:
array_slice (vec<OtherT> &v)
: m_base (v.address ()), m_size (v.length ()) {}
- template<typename OtherT>
- array_slice (const vec<OtherT, va_gc> *v)
+ template<typename OtherT, typename A>
+ array_slice (const vec<OtherT, A, vl_embed> *v)
: m_base (v ? v->address () : nullptr), m_size (v ? v->length () : 0) {}
- template<typename OtherT>
- array_slice (vec<OtherT, va_gc> *v)
+ template<typename OtherT, typename A>
+ array_slice (vec<OtherT, A, vl_embed> *v)
: m_base (v ? v->address () : nullptr), m_size (v ? v->length () : 0) {}
iterator begin () { return m_base; }