re PR tree-optimization/42963 (Redundant switch labels not cleaned up anymore)

	PR tree-optimization/42963
	* tree-cfg.c (touched_switch_bbs): New static variable.
	(group_case_labels_stmt): New function broken out from ...
	(group_case_labels): ... here, use the above.
	(start_recording_case_labels): Allocate touched_switch_bbs.
	(end_recording_case_labels): Deallocate it, call
	group_case_labels_stmt.
	(gimple_redirect_edge_and_branch): Remember index of affected BB.

testsuite/
	* testsuite/gcc.dg/pr42963.c: New testcase.

From-SVN: r158345

gcc/ChangeLog

+2010-04-14  Michael Matz  <matz@suse.de>
+
+	PR tree-optimization/42963
+	* tree-cfg.c (touched_switch_bbs): New static variable.
+	(group_case_labels_stmt): New function broken out from ...
+	(group_case_labels): ... here, use the above.
+	(start_recording_case_labels): Allocate touched_switch_bbs.
+	(end_recording_case_labels): Deallocate it, call
+	group_case_labels_stmt.
+	(gimple_redirect_edge_and_branch): Remember index of affected BB.
+
 2010-04-14  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.md (*popcountsi2_cmp_zext): Remove mode attribute

gcc/testsuite/ChangeLog

+2010-04-14  Michael Matz  <matz@suse.de>
+
+	PR tree-optimization/42963
+	* testsuite/gcc.dg/pr42963.c: New testcase.
+
 2010-04-14  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/class_wide.adb: Rename into...

gcc/testsuite/gcc.dg/pr42963.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-cfg" } */
+extern void foo (void);
+extern int i;
+void
+bar (void)
+{
+  switch (i)
+    {
+    case 0:
+      foo ();
+      break;
+    case 1:
+      break;
+    }
+
+
+  switch (i)
+    {
+    case 0:
+      foo ();
+      break;
+    case 1:
+      break;
+    }
+}
+/* { dg-final { scan-tree-dump-times "case 1:" 0 "cfg" } } */
+/* { dg-final { cleanup-tree-dump "cfg" } } */

gcc/tree-cfg.c

@@ -71,6 +71,12 @@ static const int initial_cfg_capacity = 20;
 
 static struct pointer_map_t *edge_to_cases;
 
+/* If we record edge_to_cases, this bitmap will hold indexes
+   of basic blocks that end in a GIMPLE_SWITCH which we touched
+   due to edge manipulations.  */
+
+static bitmap touched_switch_bbs;
+
 /* CFG statistics.  */
 struct cfg_stats_d
 {
@@ -122,6 +128,7 @@ static edge find_taken_edge_computed_goto (basic_block, tree);
 static edge find_taken_edge_cond_expr (basic_block, tree);
 static edge find_taken_edge_switch_expr (basic_block, tree);
 static tree find_case_label_for_value (gimple, tree);
+static void group_case_labels_stmt (gimple);
 
 void
 init_empty_tree_cfg_for_function (struct function *fn)
@@ -848,6 +855,7 @@ start_recording_case_labels (void)
 {
   gcc_assert (edge_to_cases == NULL);
   edge_to_cases = pointer_map_create ();
+  touched_switch_bbs = BITMAP_ALLOC (NULL);
 }
 
 /* Return nonzero if we are recording information for case labels.  */
@@ -863,9 +871,22 @@ recording_case_labels_p (void)
 void
 end_recording_case_labels (void)
 {
+  bitmap_iterator bi;
+  unsigned i;
   pointer_map_traverse (edge_to_cases, edge_to_cases_cleanup, NULL);
   pointer_map_destroy (edge_to_cases);
   edge_to_cases = NULL;
+  EXECUTE_IF_SET_IN_BITMAP (touched_switch_bbs, 0, i, bi)
+    {
+      basic_block bb = BASIC_BLOCK (i);
+      if (bb)
+	{
+	  gimple stmt = last_stmt (bb);
+	  if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
+	    group_case_labels_stmt (stmt);
+	}
+    }
+  BITMAP_FREE (touched_switch_bbs);
 }
 
 /* If we are inside a {start,end}_recording_cases block, then return
@@ -1278,21 +1299,13 @@ cleanup_dead_labels (void)
   free (label_for_bb);
 }
 
-/* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
-   and scan the sorted vector of cases.  Combine the ones jumping to the
-   same label.
+/* Scan the sorted vector of cases in STMT (a GIMPLE_SWITCH) and combine
+   the ones jumping to the same label.
    Eg. three separate entries 1: 2: 3: become one entry 1..3:  */
 
-void
-group_case_labels (void)
+static void
+group_case_labels_stmt (gimple stmt)
 {
-  basic_block bb;
-
-  FOR_EACH_BB (bb)
-    {
-      gimple stmt = last_stmt (bb);
-      if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
-	{
   int old_size = gimple_switch_num_labels (stmt);
   int i, j, new_size = old_size;
   tree default_case = NULL_TREE;
@@ -1379,7 +1392,22 @@ group_case_labels (void)
 
   gcc_assert (new_size <= old_size);
   gimple_switch_set_num_labels (stmt, new_size);
-	}
+}
+
+/* Look for blocks ending in a multiway branch (a GIMPLE_SWITCH),
+   and scan the sorted vector of cases.  Combine the ones jumping to the
+   same label.  */
+
+void
+group_case_labels (void)
+{
+  basic_block bb;
+
+  FOR_EACH_BB (bb)
+    {
+      gimple stmt = last_stmt (bb);
+      if (stmt && gimple_code (stmt) == GIMPLE_SWITCH)
+	group_case_labels_stmt (stmt);
     }
 }
 
@@ -4689,6 +4717,7 @@ gimple_redirect_edge_and_branch (edge e, basic_block dest)
 		TREE_CHAIN (last) = TREE_CHAIN (cases2);
 		TREE_CHAIN (cases2) = first;
 	      }
+	    bitmap_set_bit (touched_switch_bbs, gimple_bb (stmt)->index);
 	  }
 	else
 	  {