re PR tree-optimization/47053 (ICE: verify_flow_info failed: BB 2 can not throw but has an EH edge with -O -fnon-call-exceptions)

	PR tree-optimization/47053
	* tree-ssa-dse.c (need_eh_cleanup): New bitmap.
	(dse_optimize_stmt): Set the appropriate bit in NEED_EH_CLEANUP when
	statements are deleted.
	(tree_ssa_dse): Allocate & free NEED_EH_CLEANUP.  If NEED_EH_CLEANUP
	is nonempty, then purge dead edges and cleanup the CFG.

	PR tree-optimization/47053
	* g++.dg/pr47053.C: New test.

From-SVN: r169123

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 80c2622..26a438d 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -83,6 +83,10 @@ struct dse_block_local_data
   bitmap stores;
 };
 
+/* Bitmap of blocks that have had EH statements cleaned.  We should
+   remove their dead edges eventually.  */
+static bitmap need_eh_cleanup;
+
 static bool gate_dse (void);
 static unsigned int tree_ssa_dse (void);
 static void dse_initialize_block_local_data (struct dom_walk_data *,
@@ -335,6 +339,8 @@ dse_optimize_stmt (struct dse_global_data *dse_gd,
 	  /* Then we need to fix the operand of the consuming stmt.  */
 	  unlink_stmt_vdef (stmt);
 
+	  bitmap_set_bit (need_eh_cleanup, gimple_bb (stmt)->index);
+
 	  /* Remove the dead store.  */
 	  gsi_remove (&gsi, true);
 
@@ -401,6 +407,8 @@ tree_ssa_dse (void)
   struct dom_walk_data walk_data;
   struct dse_global_data dse_gd;
 
+  need_eh_cleanup = BITMAP_ALLOC (NULL);
+
   renumber_gimple_stmt_uids ();
 
   /* We might consider making this a property of each pass so that it
@@ -435,6 +443,16 @@ tree_ssa_dse (void)
   /* Release the main bitmap.  */
   BITMAP_FREE (dse_gd.stores);
 
+  /* Removal of stores may make some EH edges dead.  Purge such edges from
+     the CFG as needed.  */
+  if (!bitmap_empty_p (need_eh_cleanup))
+    {
+      gimple_purge_all_dead_eh_edges (need_eh_cleanup);
+      cleanup_tree_cfg ();
+    }
+
+  BITMAP_FREE (need_eh_cleanup);
+    
   /* For now, just wipe the post-dominator information.  */
   free_dominance_info (CDI_POST_DOMINATORS);
   return 0;