From: Devang Patel <dpatel@apple.com>
Date: Wed, 2 Mar 2005 19:45:25 +0000 (-0800)
Subject: re PR tree-optimization/18815 (Tree if-conversion screws up cfg very badly)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ac0bd8018d589a221f8ad95f7a2ddd4d228f1bb5;p=gcc.git

re PR tree-optimization/18815 (Tree if-conversion screws up cfg very badly)

       PR tree-optimization/18815
       * tree-if-conv.c (combine_blocks): Adjust loop header edges for
       loops with zero exit edges.

From-SVN: r95796
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e5e19ccd493..a4aced01cdd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2005-03-02  Devang Patel  <dpatel@apple.com>
+
+	PR tree-optimization/18815
+	* tree-if-conv.c (combine_blocks): Adjust loop header edges for
+	loops with zero exit edges.
+	
 2005-03-02  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* cfg.c (connect_src, connect_dest, disconnect_src,
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index bb832d24616..ce66e2a7bbc 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -905,11 +905,22 @@ combine_blocks (struct loop *loop)
 	continue;
 
       /* It is time to remove this basic block.	 First remove edges.  */
-      while (EDGE_COUNT (bb->succs) > 0)
-	remove_edge (EDGE_SUCC (bb, 0));
       while (EDGE_COUNT (bb->preds) > 0)
 	remove_edge (EDGE_PRED (bb, 0));
 
+      /* This is loop latch and loop does not have exit then do not
+	 delete this basic block. Just remove its PREDS and reconnect 
+	 loop->header and loop->latch blocks.  */
+      if (bb == loop->latch && loop->num_exits == 0)
+	{
+	  make_edge (loop->header, loop->latch, EDGE_FALLTHRU);
+	  set_immediate_dominator (CDI_DOMINATORS, loop->latch, loop->header);
+	  continue;
+	}
+
+      while (EDGE_COUNT (bb->succs) > 0)
+	remove_edge (EDGE_SUCC (bb, 0));
+
       /* Remove labels and make stmts member of loop->header.  */
       for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
 	{