On Wed, 27 Oct 2021 20:13:21 +0200
Aldy Hernandez via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
[would have to think about this some more but it's late here. Nits:]
> diff --git a/gcc/value-relation.cc b/gcc/value-relation.cc
> index 2acf375ca9a..0ad4f7a9495 100644
> --- a/gcc/value-relation.cc
> +++ b/gcc/value-relation.cc
> @@ -1297,8 +1297,9 @@ path_oracle::killing_def (tree ssa)
> fprintf (dump_file, "\n");
> }
>
> + unsigned v = SSA_NAME_VERSION (ssa);
> bitmap b = BITMAP_ALLOC (&m_bitmaps);
> - bitmap_set_bit (b, SSA_NAME_VERSION (ssa));
> + bitmap_set_bit (b, v);
> equiv_chain *ptr = (equiv_chain *) obstack_alloc (&m_chain_obstack,
> sizeof (equiv_chain));
> ptr->m_names = b;
> @@ -1306,6 +1307,24 @@ path_oracle::killing_def (tree ssa)
> 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.
s/an /and /
> + if (!bitmap_bit_p (m_relations.m_names, v))
> + return;
> +
> + bitmap_clear_bit (m_relations.m_names, v);
IIRC bitmap_clear_bit returns true if the bit was set, false otherwise,
so should be used as if(!bitmap_clear_bit) above.
I would not be surprised if this generates better code as we probably
do not grok to optimize the !bit_p else clear_bit combo. Shame (?).
> + relation_chain **prev = &(m_relations.m_head);
s/[()]//
thanks,
> + relation_chain *next = NULL;
> + for (relation_chain *ptr = m_relations.m_head; ptr; ptr = next)
> + {
> + gcc_checking_assert (*prev == ptr);
> + next = ptr->m_next;
> + if (SSA_NAME_VERSION (ptr->op1 ()) == v
> + || SSA_NAME_VERSION (ptr->op2 ()) == v)
> + *prev = ptr->m_next;
> + else
> + prev = &(ptr->m_next);
> + }
> }
>
> // Register relation K between SSA1 and SSA2, resolving unknowns by
