[gcc r16-981] scc_copy: conditional return TODO_cleanup_cfg.

[Andrew Pinski via Gcc-cvs]

https://gcc.gnu.org/g:62ed7fb5259bbcc3268d6801a077903c38fc3b22

commit r16-981-g62ed7fb5259bbcc3268d6801a077903c38fc3b22
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date:   Thu May 29 15:07:38 2025 -0700

    scc_copy: conditional return TODO_cleanup_cfg.
    
    Only have cleanup cfg happen if scc copy did some proping.
    This should be a small compile time improvement by not doing cleanup
    cfg if scc copy does nothing.
    
    Also removes TODO_update_ssa since it should not be needed.
    
    gcc/ChangeLog:
    
            * gimple-ssa-sccopy.cc (scc_copy_prop::replace_scc_by_value): 
Return true
            if something was done.
            (scc_copy_prop::propagate): Return true if something was changed.
            (pass_sccopy::execute): Return TODO_cleanup_cfg if a prop happened.
    
    Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>

Diff:
---
 gcc/gimple-ssa-sccopy.cc | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/gcc/gimple-ssa-sccopy.cc b/gcc/gimple-ssa-sccopy.cc
index ee2a7fa8a727..c93374572a9e 100644
--- a/gcc/gimple-ssa-sccopy.cc
+++ b/gcc/gimple-ssa-sccopy.cc
@@ -464,7 +464,7 @@ class scc_copy_prop
 public:
   scc_copy_prop ();
   ~scc_copy_prop ();
-  void propagate ();
+  bool propagate ();
 
 private:
   /* Bitmap tracking statements which were propagated so that they can be
@@ -474,15 +474,16 @@ private:
   void visit_op (tree op, hash_set<tree> &outer_ops,
                                hash_set<gimple *> &scc_set, bool &is_inner,
                                tree &last_outer_op);
-  void replace_scc_by_value (vec<gimple *> scc, tree val);
+  bool replace_scc_by_value (vec<gimple *> scc, tree val);
 };
 
 /* For each statement from given SCC, replace its usages by value
    VAL.  */
 
-void
+bool
 scc_copy_prop::replace_scc_by_value (vec<gimple *> scc, tree val)
 {
+  bool didsomething = false;
   for (gimple *stmt : scc)
     {
       tree name = gimple_get_lhs (stmt);
@@ -497,10 +498,12 @@ scc_copy_prop::replace_scc_by_value (vec<gimple *> scc, 
tree val)
        }
       replace_uses_by (name, val);
       bitmap_set_bit (dead_stmts, SSA_NAME_VERSION (name));
+      didsomething = true;
     }
 
   if (dump_file)
     fprintf (dump_file, "Replacing SCC of size %d\n", scc.length ());
+  return didsomething;
 }
 
 /* Part of 'scc_copy_prop::propagate ()'.  */
@@ -566,9 +569,10 @@ scc_copy_prop::visit_op (tree op, hash_set<tree> 
&outer_ops,
      Braun, Buchwald, Hack, Leissa, Mallon, Zwinkau, 2013, LNCS vol. 7791,
      Section 3.2.  */
 
-void
+bool
 scc_copy_prop::propagate ()
 {
+  bool didsomething = false;
   auto_vec<gimple *> useful_stmts = get_all_stmt_may_generate_copy ();
   scc_discovery discovery;
 
@@ -636,7 +640,7 @@ scc_copy_prop::propagate ()
        {
          /* The only operand in outer_ops.  */
          tree outer_op = last_outer_op;
-         replace_scc_by_value (scc, outer_op);
+         didsomething |= replace_scc_by_value (scc, outer_op);
        }
       else if (outer_ops.elements () > 1)
        {
@@ -651,6 +655,7 @@ scc_copy_prop::propagate ()
 
       scc.release ();
     }
+  return didsomething;
 }
 
 scc_copy_prop::scc_copy_prop ()
@@ -683,7 +688,7 @@ const pass_data pass_data_sccopy =
   0, /* properties_provided */
   0, /* properties_destroyed */
   0, /* todo_flags_start */
-  TODO_update_ssa | TODO_cleanup_cfg, /* todo_flags_finish */
+  0, /* todo_flags_finish */
 };
 
 class pass_sccopy : public gimple_opt_pass
@@ -703,8 +708,7 @@ unsigned
 pass_sccopy::execute (function *)
 {
   scc_copy_prop sccopy;
-  sccopy.propagate ();
-  return 0;
+  return sccopy.propagate () ?  TODO_cleanup_cfg : 0;
 }
 
 } // anon namespace