[PATCH] Cleanup back_threader::find_path_to_names.

Aldy Hernandez aldyh@redhat.com
Fri Nov 5 15:09:05 GMT 2021


The main path discovery function was due for a cleanup.  First,
there's a nagging goto and second, my bitmap use was sloppy.  Hopefully
this makes the code easier for others to read.

Regstrapped on x86-64 Linux.  I also made sure there were no difference
in the number of threads with this patch.

No functional changes.

OK?

gcc/ChangeLog:

	* tree-ssa-threadbackward.c (back_threader::find_paths_to_names):
	Remove gotos and other cleanups.
---
 gcc/tree-ssa-threadbackward.c | 52 ++++++++++++++---------------------
 1 file changed, 20 insertions(+), 32 deletions(-)

diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c
index b7eaff94567..d6a5b0b8da2 100644
--- a/gcc/tree-ssa-threadbackward.c
+++ b/gcc/tree-ssa-threadbackward.c
@@ -402,26 +402,18 @@ back_threader::find_paths_to_names (basic_block bb, bitmap interesting)
 
   m_path.safe_push (bb);
 
+  // Try to resolve the path without looking back.
   if (m_path.length () > 1
-      && !m_profit.profitable_path_p (m_path, m_name, NULL))
+      && (!m_profit.profitable_path_p (m_path, m_name, NULL)
+	  || maybe_register_path ()))
     {
       m_path.pop ();
       m_visited_bbs.remove (bb);
       return false;
     }
 
-  // Try to resolve the path without looking back.
-  if (m_path.length () > 1 && maybe_register_path ())
-    {
-      m_path.pop ();
-      m_visited_bbs.remove (bb);
-      return true;
-    }
-
   auto_bitmap processed;
-  unsigned i;
   bool done = false;
-
   // We use a worklist instead of iterating through the bitmap,
   // because we may add new items in-flight.
   auto_vec<tree> worklist (bitmap_count_bits (interesting));
@@ -433,34 +425,30 @@ back_threader::find_paths_to_names (basic_block bb, bitmap interesting)
       basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (name));
 
       // Process any names defined in this block.
-      if (def_bb == bb)
+      if (def_bb == bb
+	  && bitmap_set_bit (processed, i)
+	  && resolve_def (name, interesting, worklist))
 	{
-	  bitmap_set_bit (processed, i);
-
-	  if (resolve_def (name, interesting, worklist))
-	    {
-	      done = true;
-	      goto leave_bb;
-	    }
+	  done = true;
+	  break;
 	}
     }
-
   // If there are interesting names not yet processed, keep looking.
-  bitmap_and_compl_into (interesting, processed);
-  if (!bitmap_empty_p (interesting))
+  if (!done)
     {
-      edge_iterator iter;
-      edge e;
-      FOR_EACH_EDGE (e, iter, bb->preds)
-	if ((e->flags & EDGE_ABNORMAL) == 0)
-	  done |= find_paths_to_names (e->src, interesting);
+      bitmap_and_compl_into (interesting, processed);
+      if (!bitmap_empty_p (interesting))
+	{
+	  edge_iterator iter;
+	  edge e;
+	  FOR_EACH_EDGE (e, iter, bb->preds)
+	    if ((e->flags & EDGE_ABNORMAL) == 0)
+	      done |= find_paths_to_names (e->src, interesting);
+	}
     }
 
- leave_bb:
-  bitmap_iterator bi;
-  EXECUTE_IF_SET_IN_BITMAP (processed, 0, i, bi)
-    bitmap_set_bit (interesting, i);
-
+  // Reset things to their original state.
+  bitmap_ior_into (interesting, processed);
   m_path.pop ();
   m_visited_bbs.remove (bb);
   return done;
-- 
2.31.1



More information about the Gcc-patches mailing list