[Bug java/16451] New: [3.5 regression] Class Initialisation Check Optimisation Lost With Tree-SSA

["rmathew at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

Post tree-ssa merge, we lost the little hack that 
implemented this class initialisation optimisation:

  http://gcc.gnu.org/ml/java/1999-q3/msg00124.html

Moreover, emit_init_test_initialization() which implemented
it was removed by this patch:

  http://gcc.gnu.org/ml/gcc-patches/2004-07/msg00743.html

We need to restore the same hack (or something that
achieves the same optimisation) using trees.

The body of the said function looked like this before
it was removed:

-/* Called for every element in DECL_FUNCTION_INIT_TEST_TABLE of a
-   method in order to emit initialization code for each test flag.  */
-
-static int
-emit_init_test_initialization (void **entry, void *x ATTRIBUTE_UNUSED)
-{
-  struct treetreehash_entry *ite = (struct treetreehash_entry *) *entry;
-  tree klass = build_class_ref (ite->key);
-  tree rhs;
-
-  /* If the DECL_INITIAL of the test flag is set to true, it
-     means that the class is already initialized the time it
-     is in use. */
-  if (DECL_INITIAL (ite->value) == boolean_true_node)
-    rhs = boolean_true_node;
-  /* Otherwise, we initialize the class init check variable by looking
-     at the `state' field of the class to see if it is already
-     initialized.  This makes things a bit faster if the class is
-     already initialized, which should be the common case.  */
-  else
-    rhs = build (GE_EXPR, boolean_type_node,
-		 build (COMPONENT_REF, byte_type_node,
-			build1 (INDIRECT_REF, class_type_node, klass),
-			lookup_field (&class_type_node,
-				      get_identifier ("state")),
-			NULL_TREE),
-		 build_int_2 (JV_STATE_DONE, 0));
-
-  expand_expr_stmt (build (MODIFY_EXPR, boolean_type_node, 
-			   ite->value, rhs));
-  return true;
-}
-

-- 
           Summary: [3.5 regression] Class Initialisation Check Optimisation
                    Lost With Tree-SSA
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: java
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rmathew at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org,java-prs at gcc dot gnu
                    dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16451