From: Andrew Pinski <andrew.pinski@oss.qualcomm.com>
Date: Sat, 15 Nov 2025 22:51:32 +0000 (-0800)
Subject: cfglceanup: Fix check for preheaders
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b2e40fc16eb174ff8d97295367806dd93a0b189e;p=thirdparty%2Fgcc.git

cfglceanup: Fix check for preheaders

I had messed up the check in r16-5258-g1d8e2d51e5c5cb for preheaders
where return to remvoe the forwarder preheader block even if LOOPS_HAVE_PREHEADERS
was set. I am not sure how often this happens because most of the time the pre-header
will have an incoming phi block anyways but it is safer not to remove it in this case.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* tree-cfgcleanup.cc (tree_forwarder_block_p): Restore check on
	LOOPS_HAVE_PREHEADERS.

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

diff --git a/gcc/tree-cfgcleanup.cc b/gcc/tree-cfgcleanup.cc
index ac1394ac1d4..a78b711d82c 100644
--- a/gcc/tree-cfgcleanup.cc
+++ b/gcc/tree-cfgcleanup.cc
@@ -519,11 +519,14 @@ tree_forwarder_block_p (basic_block bb)
 	    }
 	  /* cleanup_tree_cfg_noloop just created the loop preheader, don't
 	     remove it if it has phis.  */
-	  else if (bb->loop_father == loop_outer (dest->loop_father))
-	    return gimple_seq_empty_p (phi_nodes (bb));
-	  /* Always preserve other edges into loop headers that are
-	     not simple latches or preheaders.  */
-	  return false;
+	  else if (bb->loop_father == loop_outer (dest->loop_father)
+		   && gimple_seq_empty_p (phi_nodes (bb))
+		   && !loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS))
+	    ;
+	  else
+	    /* Always preserve other edges into loop headers that are
+	       not simple latches or preheaders.  */
+	    return false;
 	}
     }