re PR tree-optimization/17343 (a dispatch table can be shortened for certain switch statements)

2004-10-01  Andrew Pinski  <pinskia@physics.uc.edu>

        PR tree-opt/17343
        * gcc.dg/tree-ssa/pr17343.c: New test.

2004-10-01  Andrew Pinski  <pinskia@physics.uc.edu>

        PR tree-opt/17343
        * tree-cfg.c (group_case_labels): Get the label and not
        the case expr for the default case.
        When the label we looking at is the default, decrement the
        new_size.

From-SVN: r88397

gcc/ChangeLog

+2004-10-01  Andrew Pinski  <pinskia@physics.uc.edu>
+
+	PR tree-opt/17343
+	* tree-cfg.c (group_case_labels): Get the label and not
+	the case expr for the default case.
+	When the label we looking at is the default, decrement the
+	new_size.
+
 2004-10-01  Jan Hubicka  <jh@suse.cz>
 
 	* c-decl.c (c_expand_body): Update call tree_rest_of_compilation.

gcc/testsuite/ChangeLog

+2004-10-01  Andrew Pinski  <pinskia@physics.uc.edu>
+
+	PR tree-opt/17343
+	* gcc.dg/tree-ssa/pr17343.c: New test.
+
 2004-10-01  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcc.dg/tree-ssa/stdarg-1.c: Removed.

gcc/testsuite/gcc.dg/tree-ssa/pr17343.c

+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+void foo0(void);
+void foo1(void);
+void foo2(void);
+void foo3(void);
+
+void
+foo (int a)
+{
+  switch (a)
+    {
+    case 10:
+    case 11:
+    case 12:
+    case 13:
+      goto ddd;
+    case 14:
+      foo1();
+      break;
+    case 15:
+      foo2();
+      break;
+    case 16:
+      foo3();
+      break;
+    default:
+    ddd:
+      foo0();
+      break;
+    }
+}
+/* There should be precisely two references to ddd.  One in the switch
+   and one for the label, we used not to combine the case 10-13 into
+   the default case.  */
+/* { dg-final { scan-tree-dump-times "ddd" 1 "optimized"} } */

gcc/tree-cfg.c

@@ -941,7 +941,12 @@ group_case_labels (void)
 	  tree labels = SWITCH_LABELS (stmt);
 	  int old_size = TREE_VEC_LENGTH (labels);
 	  int i, j, new_size = old_size;
-	  tree default_label = TREE_VEC_ELT (labels, old_size - 1);
+	  tree default_case = TREE_VEC_ELT (labels, old_size - 1);
+ 	  tree default_label;
+
+	  /* The default lable is always the last case in a switch
+	     statement after gimplification.  */
+	  default_label = CASE_LABEL (default_case);
 
 	  /* Look for possible opportunities to merge cases.
 	     Ignore the last element of the label vector because it
@@ -961,6 +966,7 @@ group_case_labels (void)
 		{
 		  TREE_VEC_ELT (labels, i) = NULL_TREE;
 		  i++;
+		  new_size--;
 		  continue;
 		}