[PATCH] path relation oracle: Remove SSA's being killed from the equivalence list.

[PATCH] path relation oracle: Remove SSA's being killed from the equivalence list.

[Aldy Hernandez]

Same thing as the relational change.  Walk any equivalences that have
been registered on the path, and remove the name being killed.  The
only reason we had added the equivalence with itself earlier is so we
wouldn't search any further in the equivalency list.  So if we are
removing all references to it, then we no longer need to add a "kill"
record.

Will push pending tests on x86-64 Linux.

Co-authored-by: Andrew MacLeod <amacleod@redhat.com>

gcc/ChangeLog:

	* value-relation.cc (path_oracle::killing_def): Walk the
	equivalency list and remove SSA from any equivalencies.
---
 gcc/value-relation.cc | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/gcc/value-relation.cc b/gcc/value-relation.cc
index 0ad4f7a9495..512b51ce022 100644
--- a/gcc/value-relation.cc
+++ b/gcc/value-relation.cc
@@ -1298,17 +1298,17 @@ path_oracle::killing_def (tree ssa)
     }
 
   unsigned v = SSA_NAME_VERSION (ssa);
-  bitmap b = BITMAP_ALLOC (&m_bitmaps);
-  bitmap_set_bit (b, v);
-  equiv_chain *ptr = (equiv_chain *) obstack_alloc (&m_chain_obstack,
-						    sizeof (equiv_chain));
-  ptr->m_names = b;
-  ptr->m_bb = NULL;
-  ptr->m_next = m_equiv.m_next;
-  m_equiv.m_next = ptr;
-  bitmap_ior_into (m_equiv.m_names, b);
 
-  // Walk the relation list an remove SSA from any relations.
+  // Walk the equivalency list and remove SSA from any equivalencies.
+  if (bitmap_bit_p (m_equiv.m_names, v))
+    {
+      bitmap_clear_bit (m_equiv.m_names, v);
+      for (equiv_chain *ptr = m_equiv.m_next; ptr; ptr = ptr->m_next)
+	if (bitmap_bit_p (ptr->m_names, v))
+	  bitmap_clear_bit (ptr->m_names, v);
+    }
+
+  // Walk the relation list and remove SSA from any relations.
   if (!bitmap_bit_p (m_relations.m_names, v))
     return;
 
-- 
2.31.1

Re: [PATCH] path relation oracle: Remove SSA's being killed from the equivalence list.

[Richard Biener]

On Thu, Oct 28, 2021 at 5:25 PM Aldy Hernandez via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Same thing as the relational change.  Walk any equivalences that have
> been registered on the path, and remove the name being killed.  The
> only reason we had added the equivalence with itself earlier is so we
> wouldn't search any further in the equivalency list.  So if we are
> removing all references to it, then we no longer need to add a "kill"
> record.
>
> Will push pending tests on x86-64 Linux.
>
> Co-authored-by: Andrew MacLeod <amacleod@redhat.com>
>
> gcc/ChangeLog:
>
>         * value-relation.cc (path_oracle::killing_def): Walk the
>         equivalency list and remove SSA from any equivalencies.
> ---
>  gcc/value-relation.cc | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/value-relation.cc b/gcc/value-relation.cc
> index 0ad4f7a9495..512b51ce022 100644
> --- a/gcc/value-relation.cc
> +++ b/gcc/value-relation.cc
> @@ -1298,17 +1298,17 @@ path_oracle::killing_def (tree ssa)
>      }
>
>    unsigned v = SSA_NAME_VERSION (ssa);
> -  bitmap b = BITMAP_ALLOC (&m_bitmaps);
> -  bitmap_set_bit (b, v);
> -  equiv_chain *ptr = (equiv_chain *) obstack_alloc (&m_chain_obstack,
> -                                                   sizeof (equiv_chain));
> -  ptr->m_names = b;
> -  ptr->m_bb = NULL;
> -  ptr->m_next = m_equiv.m_next;
> -  m_equiv.m_next = ptr;
> -  bitmap_ior_into (m_equiv.m_names, b);
>
> -  // Walk the relation list an remove SSA from any relations.
> +  // Walk the equivalency list and remove SSA from any equivalencies.
> +  if (bitmap_bit_p (m_equiv.m_names, v))
> +    {
> +      bitmap_clear_bit (m_equiv.m_names, v);
> +      for (equiv_chain *ptr = m_equiv.m_next; ptr; ptr = ptr->m_next)
> +       if (bitmap_bit_p (ptr->m_names, v))
> +         bitmap_clear_bit (ptr->m_names, v);

What's the reason to do both lookup and clear?  Just bitmap_clear_bit ()
should be good enough.

> +    }
> +
> +  // Walk the relation list and remove SSA from any relations.
>    if (!bitmap_bit_p (m_relations.m_names, v))
>      return;
>
> --
> 2.31.1
>