From: Andrew Pinski <andrew.pinski@oss.qualcomm.com>
Date: Sun, 9 Nov 2025 06:40:08 +0000 (-0800)
Subject: mergephi: Remove worklist
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=38155f105cca2a3b5a88faf5a1fc2a8332705e37;p=thirdparty%2Fgcc.git

mergephi: Remove worklist

Since the worklist was never added to and the anlysis part can benifit
from the work part, we can combine the analayis part with the work part.
This should get a small speedup for this pass

Looking into the history here, remove_forwarder_block used to add to the worklist
but remove_forwarder_block_with_phi never did.

This is the first step in moving part of the functionality of mergephi into
cfgcleanup.

gcc/ChangeLog:

	* tree-cfgcleanup.cc (pass_merge_phi::execute): Remove worklist.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>
---

diff --git a/gcc/tree-cfgcleanup.cc b/gcc/tree-cfgcleanup.cc
index 58e8af5efcf..2e613df6855 100644
--- a/gcc/tree-cfgcleanup.cc
+++ b/gcc/tree-cfgcleanup.cc
@@ -1456,16 +1456,17 @@ public:
 unsigned int
 pass_merge_phi::execute (function *fun)
 {
-  basic_block *worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (fun));
-  basic_block *current = worklist;
-  basic_block bb;
-
   calculate_dominance_info (CDI_DOMINATORS);
 
   /* Find all PHI nodes that we may be able to merge.  */
-  FOR_EACH_BB_FN (bb, fun)
+  bool changed = false;
+  unsigned n = last_basic_block_for_fn (fun);
+  for (unsigned i = NUM_FIXED_BLOCKS; i < n; i++)
     {
       basic_block dest;
+      basic_block bb = BASIC_BLOCK_FOR_FN (fun, i);
+      if (!bb)
+	continue;
 
       /* Look for a forwarder block with PHI nodes.  */
       if (!tree_forwarder_block_p (bb, true))
@@ -1481,14 +1482,10 @@ pass_merge_phi::execute (function *fun)
 	  || bb_has_abnormal_pred (bb))
 	continue;
 
-      if (!dominated_by_p (CDI_DOMINATORS, dest, bb))
-	{
-	  /* If BB does not dominate DEST, then the PHI nodes at
-	     DEST must be the only users of the results of the PHI
-	     nodes at BB.  */
-	  *current++ = bb;
-	}
-      else
+     /* If BB does not dominate DEST, then the PHI nodes at
+	DEST must be the only users of the results of the PHI
+	nodes at BB. So only check when BB dominates dest.  */
+      if (dominated_by_p (CDI_DOMINATORS, dest, bb))
 	{
 	  gphi_iterator gsi;
 	  unsigned int dest_idx = single_succ_edge (bb)->dest_idx;
@@ -1521,19 +1518,11 @@ pass_merge_phi::execute (function *fun)
 
 	  /* If the loop above iterated through all the PHI nodes
 	     in BB, then we can merge the PHIs from BB into DEST.  */
-	  if (gsi_end_p (gsi))
-	    *current++ = bb;
+	  if (!gsi_end_p (gsi))
+	    continue;
 	}
-    }
-
-  /* Now let's drain WORKLIST.  */
-  bool changed = false;
-  while (current != worklist)
-    {
-      bb = *--current;
       changed |= remove_forwarder_block_with_phi (bb);
     }
-  free (worklist);
 
   /* Removing forwarder blocks can cause formerly irreducible loops
      to become reducible if we merged two entry blocks.  */