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/* Handle exceptional things in C++.

   Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,

   2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

   Contributed by Michael Tiemann <tiemann@cygnus.com>

   Rewritten by Mike Stump <mrs@cygnus.com>, based upon an

   initial re-implementation courtesy Tad Hunt.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3, or (at your option)

any later version.

GCC is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "tree.h"

#include "rtl.h"

#include "expr.h"

#include "libfuncs.h"

#include "cp-tree.h"

#include "flags.h"

#include "output.h"

#include "except.h"

#include "toplev.h"

#include "tree-inline.h"

#include "tree-iterator.h"

#include "target.h"

#include "gimple.h"

static void push_eh_cleanup (tree);

static tree prepare_eh_type (tree);

static tree do_begin_catch (void);

static int dtor_nothrow (tree);

static tree do_end_catch (tree);

static bool decl_is_java_type (tree decl, int err);

static void initialize_handler_parm (tree, tree);

static tree do_allocate_exception (tree);

static tree wrap_cleanups_r (tree *, int *, void *);

static int complete_ptr_ref_or_void_ptr_p (tree, tree);

static bool is_admissible_throw_operand (tree);

static int can_convert_eh (tree, tree);

static tree cp_protect_cleanup_actions (void);

/* Sets up all the global eh stuff that needs to be initialized at the

   start of compilation.  */

void

init_exception_processing (void)

{

  tree tmp;

  /* void std::terminate (); */

  push_namespace (std_identifier);

  tmp = build_function_type (void_type_node, void_list_node);

  terminate_node = build_cp_library_fn_ptr ("terminate", tmp);

  TREE_THIS_VOLATILE (terminate_node) = 1;

  TREE_NOTHROW (terminate_node) = 1;

  pop_namespace ();

  /* void __cxa_call_unexpected(void *); */

  tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);

  tmp = build_function_type (void_type_node, tmp);

  call_unexpected_node

    = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);

  lang_protect_cleanup_actions = &cp_protect_cleanup_actions;

}

/* Returns an expression to be executed if an unhandled exception is

   propagated out of a cleanup region.  */

static tree

cp_protect_cleanup_actions (void)

{

  /* [except.terminate]

     When the destruction of an object during stack unwinding exits

     using an exception ... void terminate(); is called.  */

  return terminate_node;

}

static tree

prepare_eh_type (tree type)

{

  if (type == NULL_TREE)

    return type;

  if (type == error_mark_node)

    return error_mark_node;

  /* peel back references, so they match.  */

  type = non_reference (type);

  /* Peel off cv qualifiers.  */

  type = TYPE_MAIN_VARIANT (type);

  /* Functions and arrays decay to pointers.  */

  type = type_decays_to (type);

  return type;

}

/* Return the type info for TYPE as used by EH machinery.  */

tree

eh_type_info (tree type)

{

  tree exp;

  if (type == NULL_TREE || type == error_mark_node)

    return type;

  if (decl_is_java_type (type, 0))

    exp = build_java_class_ref (TREE_TYPE (type));

  else

    exp = get_tinfo_decl (type);

  return exp;

}

/* Build the address of a typeinfo decl for use in the runtime

   matching field of the exception model.  */

tree

build_eh_type_type (tree type)

{

  tree exp = eh_type_info (type);

  if (!exp)

    return NULL;

  mark_used (exp);

  return convert (ptr_type_node, build_address (exp));

}

tree

build_exc_ptr (void)

{

  return build_call_n (built_in_decls [BUILT_IN_EH_POINTER],

                       1, integer_zero_node);

}

/* Declare a function NAME, returning RETURN_TYPE, taking a single

   parameter PARM_TYPE, with an empty exception specification.

   Note that the C++ ABI document does not have a throw-specifier on

   the routines declared below via this function.  The declarations

   are consistent with the actual implementations in libsupc++.  */

static tree

declare_nothrow_library_fn (tree name, tree return_type, tree parm_type)

{

  tree tmp = tree_cons (NULL_TREE, parm_type, void_list_node);

  return push_library_fn (name, build_function_type (return_type, tmp),

                          empty_except_spec);

}

/* Build up a call to __cxa_get_exception_ptr so that we can build a

   copy constructor for the thrown object.  */

static tree

do_get_exception_ptr (void)

{

  tree fn;

  fn = get_identifier ("__cxa_get_exception_ptr");

  if (!get_global_value_if_present (fn, &fn))

    {

      /* Declare void* __cxa_get_exception_ptr (void *) throw().  */

      fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);

    }

  return cp_build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),

                                                NULL_TREE),

                                 tf_warning_or_error);

}

/* Build up a call to __cxa_begin_catch, to tell the runtime that the

   exception has been handled.  */

static tree

do_begin_catch (void)

{

  tree fn;

  fn = get_identifier ("__cxa_begin_catch");

  if (!get_global_value_if_present (fn, &fn))

    {

      /* Declare void* __cxa_begin_catch (void *) throw().  */

      fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);

    }

  return cp_build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),

                                                NULL_TREE),

                                 tf_warning_or_error);

}

/* Returns nonzero if cleaning up an exception of type TYPE (which can be

   NULL_TREE for a ... handler) will not throw an exception.  */

static int

dtor_nothrow (tree type)

{

  if (type == NULL_TREE || type == error_mark_node)

    return 0;

  if (TYPE_HAS_TRIVIAL_DESTRUCTOR (type))

    return 1;

  if (CLASSTYPE_LAZY_DESTRUCTOR (type))

    lazily_declare_fn (sfk_destructor, type);

  return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));

}

/* Build up a call to __cxa_end_catch, to destroy the exception object

   for the current catch block if no others are currently using it.  */

static tree

do_end_catch (tree type)

{

  tree fn, cleanup;

  fn = get_identifier ("__cxa_end_catch");

  if (!get_global_value_if_present (fn, &fn))

    {

      /* Declare void __cxa_end_catch ().  */

      fn = push_void_library_fn (fn, void_list_node);

      /* This can throw if the destructor for the exception throws.  */

      TREE_NOTHROW (fn) = 0;

    }

  cleanup = cp_build_function_call (fn, NULL_TREE, tf_warning_or_error);

  TREE_NOTHROW (cleanup) = dtor_nothrow (type);

  return cleanup;

}

/* This routine creates the cleanup for the current exception.  */

static void

push_eh_cleanup (tree type)

{

  finish_decl_cleanup (NULL_TREE, do_end_catch (type));

}

/* Return nonzero value if DECL is a Java type suitable for catch or

   throw.  */

static bool

decl_is_java_type (tree decl, int err)

{

  bool r = (TREE_CODE (decl) == POINTER_TYPE

            && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE

            && TYPE_FOR_JAVA (TREE_TYPE (decl)));

  if (err)

    {

      if (TREE_CODE (decl) == REFERENCE_TYPE

          && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE

          && TYPE_FOR_JAVA (TREE_TYPE (decl)))

        {

          /* Can't throw a reference.  */

          error ("type %qT is disallowed in Java %<throw%> or %<catch%>",

                 decl);

        }

      if (r)

        {

          tree jthrow_node

            = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));

          if (jthrow_node == NULL_TREE)

            fatal_error

              ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");

          jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));

          if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))

            {

              /* Thrown object must be a Throwable.  */

              error ("type %qT is not derived from %<java::lang::Throwable%>",

                     TREE_TYPE (decl));

            }

        }

    }

  return r;

}

/* Select the personality routine to be used for exception handling,

   or issue an error if we need two different ones in the same

   translation unit.

   ??? At present eh_personality_decl is set to

   __gxx_personality_(sj|v)0 in init_exception_processing - should it

   be done here instead?  */

void

choose_personality_routine (enum languages lang)

{

  static enum {

    chose_none,

    chose_cpp,

    chose_java,

    gave_error

  } state;

  switch (state)

    {

    case gave_error:

      return;

    case chose_cpp:

      if (lang != lang_cplusplus)

        goto give_error;

      return;

    case chose_java:

      if (lang != lang_java)

        goto give_error;

      return;

    case chose_none:

      ; /* Proceed to language selection.  */

    }

  switch (lang)

    {

    case lang_cplusplus:

      state = chose_cpp;

      break;

    case lang_java:

      state = chose_java;

      terminate_node = built_in_decls [BUILT_IN_ABORT];

      pragma_java_exceptions = true;

      break;

    default:

      gcc_unreachable ();

    }

  return;

 give_error:

  error ("mixing C++ and Java catches in a single translation unit");

  state = gave_error;

}

/* Initialize the catch parameter DECL.  */

static void

initialize_handler_parm (tree decl, tree exp)

{

  tree init;

  tree init_type;

  /* Make sure we mark the catch param as used, otherwise we'll get a

     warning about an unused ((anonymous)).  */

  TREE_USED (decl) = 1;

  /* Figure out the type that the initializer is.  Pointers are returned

     adjusted by value from __cxa_begin_catch.  Others are returned by

     reference.  */

  init_type = TREE_TYPE (decl);

  if (!POINTER_TYPE_P (init_type))

    init_type = build_reference_type (init_type);

  choose_personality_routine (decl_is_java_type (init_type, 0)

                              ? lang_java : lang_cplusplus);

  /* Since pointers are passed by value, initialize a reference to

     pointer catch parm with the address of the temporary.  */

  if (TREE_CODE (init_type) == REFERENCE_TYPE

      && TYPE_PTR_P (TREE_TYPE (init_type)))

    exp = cp_build_unary_op (ADDR_EXPR, exp, 1, tf_warning_or_error);

  exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);

  init = convert_from_reference (exp);

  /* If the constructor for the catch parm exits via an exception, we

     must call terminate.  See eh23.C.  */

  if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))

    {

      /* Generate the copy constructor call directly so we can wrap it.

         See also expand_default_init.  */

      init = ocp_convert (TREE_TYPE (decl), init,

                          CONV_IMPLICIT|CONV_FORCE_TEMP, 0);

      /* Force cleanups now to avoid nesting problems with the

         MUST_NOT_THROW_EXPR.  */

      init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);

      init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);

    }

  decl = pushdecl (decl);

  start_decl_1 (decl, true);

  cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,

                  LOOKUP_ONLYCONVERTING|DIRECT_BIND);

}

/* Call this to start a catch block.  DECL is the catch parameter.  */

tree

expand_start_catch_block (tree decl)

{

  tree exp;

  tree type, init;

  if (! doing_eh (1))

    return NULL_TREE;

  /* Make sure this declaration is reasonable.  */

  if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))

    decl = error_mark_node;

  if (decl)

    type = prepare_eh_type (TREE_TYPE (decl));

  else

    type = NULL_TREE;

  if (decl && decl_is_java_type (type, 1))

    {

      /* Java only passes object via pointer and doesn't require

         adjusting.  The java object is immediately before the

         generic exception header.  */

      exp = build_exc_ptr ();

      exp = build1 (NOP_EXPR, build_pointer_type (type), exp);

      exp = build2 (POINTER_PLUS_EXPR, TREE_TYPE (exp), exp,

                    fold_build1_loc (input_location,

                                 NEGATE_EXPR, sizetype,

                                 TYPE_SIZE_UNIT (TREE_TYPE (exp))));

      exp = cp_build_indirect_ref (exp, RO_NULL, tf_warning_or_error);

      initialize_handler_parm (decl, exp);

      return type;

    }

  /* Call __cxa_end_catch at the end of processing the exception.  */

  push_eh_cleanup (type);

  init = do_begin_catch ();

  /* If there's no decl at all, then all we need to do is make sure

     to tell the runtime that we've begun handling the exception.  */

  if (decl == NULL || decl == error_mark_node || init == error_mark_node)

    finish_expr_stmt (init);

  /* If the C++ object needs constructing, we need to do that before

     calling __cxa_begin_catch, so that std::uncaught_exception gets

     the right value during the copy constructor.  */

  else if (flag_use_cxa_get_exception_ptr

           && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))

    {

      exp = do_get_exception_ptr ();

      initialize_handler_parm (decl, exp);

      finish_expr_stmt (init);

    }

  /* Otherwise the type uses a bitwise copy, and we don't have to worry

     about the value of std::uncaught_exception and therefore can do the

     copy with the return value of __cxa_end_catch instead.  */

  else

    {

      tree init_type = type;

      /* Pointers are passed by values, everything else by reference.  */

      if (!TYPE_PTR_P (type))

        init_type = build_pointer_type (type);

      if (init_type != TREE_TYPE (init))

        init = build1 (NOP_EXPR, init_type, init);

      exp = create_temporary_var (init_type);

      DECL_REGISTER (exp) = 1;

      cp_finish_decl (exp, init, /*init_const_expr=*/false,

                      NULL_TREE, LOOKUP_ONLYCONVERTING);

      initialize_handler_parm (decl, exp);

    }

  return type;

}

/* Call this to end a catch block.  Its responsible for emitting the

   code to handle jumping back to the correct place, and for emitting

   the label to jump to if this catch block didn't match.  */

void

expand_end_catch_block (void)

{

  if (! doing_eh (1))

    return;

  /* The exception being handled is rethrown if control reaches the end of

     a handler of the function-try-block of a constructor or destructor.  */

  if (in_function_try_handler

      && (DECL_CONSTRUCTOR_P (current_function_decl)

          || DECL_DESTRUCTOR_P (current_function_decl)))

    finish_expr_stmt (build_throw (NULL_TREE));

}

tree

begin_eh_spec_block (void)

{

  tree r = build_stmt (input_location, EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);

  add_stmt (r);

  EH_SPEC_STMTS (r) = push_stmt_list ();

  return r;

}

void

finish_eh_spec_block (tree raw_raises, tree eh_spec_block)

{

  tree raises;

  EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));

  /* Strip cv quals, etc, from the specification types.  */

  for (raises = NULL_TREE;

       raw_raises && TREE_VALUE (raw_raises);

       raw_raises = TREE_CHAIN (raw_raises))

    {

      tree type = prepare_eh_type (TREE_VALUE (raw_raises));

      tree tinfo = eh_type_info (type);

      mark_used (tinfo);

      raises = tree_cons (NULL_TREE, type, raises);

    }

  EH_SPEC_RAISES (eh_spec_block) = raises;

}

/* Return a pointer to a buffer for an exception object of type TYPE.  */

static tree

do_allocate_exception (tree type)

{

  tree fn;

  fn = get_identifier ("__cxa_allocate_exception");

  if (!get_global_value_if_present (fn, &fn))

    {

      /* Declare void *__cxa_allocate_exception(size_t) throw().  */

      fn = declare_nothrow_library_fn (fn, ptr_type_node, size_type_node);

    }

  return cp_build_function_call (fn,

                                 tree_cons (NULL_TREE, size_in_bytes (type),

                                            NULL_TREE),

                                 tf_warning_or_error);

}

/* Call __cxa_free_exception from a cleanup.  This is never invoked

   directly, but see the comment for stabilize_throw_expr.  */

static tree

do_free_exception (tree ptr)

{

  tree fn;

  fn = get_identifier ("__cxa_free_exception");

  if (!get_global_value_if_present (fn, &fn))

    {

      /* Declare void __cxa_free_exception (void *) throw().  */

      fn = declare_nothrow_library_fn (fn, void_type_node, ptr_type_node);

    }

  return cp_build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE),

                                 tf_warning_or_error);

}

/* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.

   Called from build_throw via walk_tree_without_duplicates.  */

static tree

wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,

                 void *data ATTRIBUTE_UNUSED)

{

  tree exp = *tp;

  tree cleanup;

  /* Don't walk into types.  */

  if (TYPE_P (exp))

    {

      *walk_subtrees = 0;

      return NULL_TREE;

    }

  if (TREE_CODE (exp) != TARGET_EXPR)

    return NULL_TREE;

  cleanup = TARGET_EXPR_CLEANUP (exp);

  if (cleanup)

    {

      cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);

      TARGET_EXPR_CLEANUP (exp) = cleanup;

    }

  /* Keep iterating.  */

  return NULL_TREE;

}

/* Build a throw expression.  */

tree

build_throw (tree exp)

{

  tree fn;

  if (exp == error_mark_node)

    return exp;

  if (processing_template_decl)

    {

      if (cfun)

        current_function_returns_abnormally = 1;

      return build_min (THROW_EXPR, void_type_node, exp);

    }

  if (exp == null_node)

    warning (0, "throwing NULL, which has integral, not pointer type");

  if (exp != NULL_TREE)

    {

      if (!is_admissible_throw_operand (exp))

        return error_mark_node;

    }

  if (! doing_eh (1))

    return error_mark_node;

  if (exp && decl_is_java_type (TREE_TYPE (exp), 1))

    {

      tree fn = get_identifier ("_Jv_Throw");

      if (!get_global_value_if_present (fn, &fn))

        {

          /* Declare void _Jv_Throw (void *).  */

          tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);

          tmp = build_function_type (ptr_type_node, tmp);

          fn = push_throw_library_fn (fn, tmp);

        }

      else if (really_overloaded_fn (fn))

        {

          error ("%qD should never be overloaded", fn);

          return error_mark_node;

        }

      fn = OVL_CURRENT (fn);

      exp = cp_build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE),

                                    tf_warning_or_error);

    }

  else if (exp)

    {

      tree throw_type;

      tree temp_type;

      tree cleanup;

      tree object, ptr;

      tree tmp;

      tree temp_expr, allocate_expr;

      bool elided;

      /* The CLEANUP_TYPE is the internal type of a destructor.  */

      if (!cleanup_type)

        {

          tmp = void_list_node;

          tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);

          tmp = build_function_type (void_type_node, tmp);

          cleanup_type = build_pointer_type (tmp);

        }

      fn = get_identifier ("__cxa_throw");

      if (!get_global_value_if_present (fn, &fn))

        {

          /* Declare void __cxa_throw (void*, void*, void (*)(void*)).  */

          /* ??? Second argument is supposed to be "std::type_info*".  */

          tmp = void_list_node;

          tmp = tree_cons (NULL_TREE, cleanup_type, tmp);

          tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);

          tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);

          tmp = build_function_type (void_type_node, tmp);

          fn = push_throw_library_fn (fn, tmp);

        }

      /* [except.throw]

         A throw-expression initializes a temporary object, the type

         of which is determined by removing any top-level

         cv-qualifiers from the static type of the operand of throw

         and adjusting the type from "array of T" or "function return

         T" to "pointer to T" or "pointer to function returning T"

         respectively.  */

      temp_type = is_bitfield_expr_with_lowered_type (exp);

      if (!temp_type)

        temp_type = type_decays_to (TREE_TYPE (exp));

      /* OK, this is kind of wacky.  The standard says that we call

         terminate when the exception handling mechanism, after

         completing evaluation of the expression to be thrown but

         before the exception is caught (_except.throw_), calls a

         user function that exits via an uncaught exception.

         So we have to protect the actual initialization of the

         exception object with terminate(), but evaluate the

         expression first.  Since there could be temps in the

         expression, we need to handle that, too.  We also expand

         the call to __cxa_allocate_exception first (which doesn't

         matter, since it can't throw).  */

      /* Allocate the space for the exception.  */

      allocate_expr = do_allocate_exception (temp_type);

      allocate_expr = get_target_expr (allocate_expr);

      ptr = TARGET_EXPR_SLOT (allocate_expr);

      object = build_nop (build_pointer_type (temp_type), ptr);

      object = cp_build_indirect_ref (object, RO_NULL, tf_warning_or_error);

      elided = (TREE_CODE (exp) == TARGET_EXPR);