[Bug tree-optimization/35869] New: ICE in calc_dfs_tree at -O2 -gnatp after VRP optimization

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

The to-be-attached Ada testcase exhibits a problem with the switch statement
optimization recently added to VRP:

        PR tree-optimization/14495
        PR tree-optimization/34793
        * tree-vrp.c (struct switch_update): New structure.
        (to_remove_edges, to_update_switch_stmts): New VECs.
        (simplify_switch_using_ranges): New function.  Remove not taken
        case labels and edges.
        (simplify_stmt_using_ranges): Call it.
        (identify_jump_threads): Mark edges we have queued for removal
        so we don't thread them.
        (execute_vrp): Remove edges queued for removal, update SWITCH_STMT
        case label vector.
        * tree-cfg.c (group_case_labels): Deal with missing default label.
        (tree_verify_flow_info): Allow missing default label.
        * stmt.c (emit_case_bit_tests): Deal with NULL default_label.
        (emit_case_nodes): Likewise.
        (expand_case): Do not rely on the default label to be present.
        * expr.c (try_casesi): Deal with NULL default_label.
        (do_tablejump): Likewise.

Quick analysis posted at
  http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00558.html


-- 
           Summary: ICE in calc_dfs_tree at -O2 -gnatp after VRP
                    optimization
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ebotcazou at gcc dot gnu dot org
GCC target triplet: i?86-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35869