Re: [RFA][PATCH] Refactor duplicated code used by various dom walkers

[Jeff Law <law at redhat dot com>]

On 11/03/2017 04:05 AM, Richard Biener wrote:
> On Fri, Nov 3, 2017 at 4:49 AM, Jeff Law <law@redhat.com> wrote:
> > Several passes which perform dominator walks want to identify when block has
> > a single incoming edge, ignoring loop backedges.
> >
> > I'm aware of 4 implementations of this code.  3 of the 4 are identical in
> > function.  The 4th (tree-ssa-dom.c) has an additional twist that it also
> > ignores edges that are not marked as executable.
> >
> > So I've taken the more general implementation from tree-ssa-dom.c and
> > conditionalized the handling of unexecutable edges on a flag and moved the
> > implementation into cfganal.c where it more naturally belongs.
> >
> > Bootstrapped and regression tested on x86_64.  OK for the trunk?
>
> Minor nits (sorry...)
No need to apologize.  I'm always appreciative of feedback as it 
consistently improves what ultimately lands in the tree.


> > Jeff
> >
> >          * cfganal.c (single_incoming_edge_ignoring_loop_edges): New function
> >          extracted from tree-ssa-dom.c.
> >          * cfganal.h (single_incoming_edge_ignoring_loop_edges): Prototype.
> >          * tree-ssa-dom.c (single_incoming_edge_ignoring_loop_edges): Remove.
> >          (record_equivalences_from_incoming_edge): Add additional argument
> >          to single_incoming_edge_ignoring_loop_edges call.
> >          * tree-ssa-uncprop.c (single_incoming_edge_ignoring_loop_edges):
> > Remove.
> >          (uncprop_dom_walker::before_dom_children): Add additional argument
> >          to single_incoming_edge_ignoring_loop_edges call.
> >          * tree-ssa-sccvn.c (sccvn_dom_walker::before_dom_children): Use
> >          single_incoming_edge_ignoring_loop_edges rather than open coding.
> >          * tree-vrp.c (evrp_dom_walker::before_dom_children): Similarly.
> >
> >
> >
> >
> >
> > diff --git a/gcc/cfganal.c b/gcc/cfganal.c
> > index c506067..14d94b2 100644
> > --- a/gcc/cfganal.c
> > +++ b/gcc/cfganal.c
> > @@ -1554,3 +1554,38 @@ single_pred_before_succ_order (void)
> >   #undef MARK_VISITED
> >   #undef VISITED_P
> >   }
> > +
> > +/* Ignoring loop backedges, if BB has precisely one incoming edge then
> > +   return that edge.  Otherwise return NULL.  */
> > +edge
> > +single_incoming_edge_ignoring_loop_edges (basic_block bb,
> > +                                         bool ignore_unreachable)
>
> single_pred_edge_ignoring_loop_edges and ignore_not_executable
>
> to better match existing CFG functions and actual edge flag use.
>
> Ok with that change.
Sure.  Easy to change.

Jeff