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[unix-history] / gnu / usr.bin / cc / cc1plus / cp-except.c

/* Handle exceptional things in C++.
   Copyright (C) 1989, 1992, 1993 Free Software Foundation, Inc.
   Contributed by Michael Tiemann (tiemann@cygnus.com)

This file is part of GNU CC.

GNU CC 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 2, or (at your option)
any later version.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


/* High-level class interface. */

#include "config.h"
#include "tree.h"
#include "rtl.h"
#include "cp-tree.h"
#include "flags.h"
/* On Suns this can get you to the right definition if you
   set the right value for TARGET.  */
#include <setjmp.h>
#ifdef sequent
/* Can you believe they forgot this?  */
#define _JBLEN 11
#endif

#ifndef _JBLEN
#define _JBLEN (sizeof(jmp_buf)/sizeof(int))
#endif

#undef NULL
#define NULL (char *)0

/* This should be part of `ansi_opname', or at least be defined by the std.  */
#define EXCEPTION_NAME_PREFIX "__ex"
#define EXCEPTION_NAME_LENGTH 4

void init_exception_processing ();
void init_exception_processing_1 ();

/* If non-zero, a VAR_DECL whose cleanup will cause a throw to the
   next exception handler.  Its value says whether to throw or not.
   In the case of functions which do not issue a RAISE, it should be
   possible to optimize away this VAR_DECL (and overhead associated
   with it).  */
tree exception_throw_decl;
/* Use this to know that we did not set `exception_throw_decl',
   until GCC optimizer is smart enough to figure it out for itself.  */
int sets_exception_throw_decl;

/* The exception `type' currently in scope, or NULL_TREE if none.  */
tree current_exception_type;

/* The exception handler object for the given scope.  */
tree current_exception_decl;
rtx current_exception_name_as_rtx;
rtx current_exception_parms_as_rtx;

/* The ``object'' view of the current exception parameters.
   We cast up from the `parms' field to `current_exception_type'.  */
tree current_exception_object;

/* Cache `setjmp', `longjmp', `raise_exception', and `unhandled_exception'
   after default conversion.  Maybe later they will get built-in.  */
static tree BISJ, BILJ, BIR, BIUE;

/* Local variables which give the appearance that exception
   handling is part of the language and the execution model.  */

/* The type of the exception handler stack.  */
static tree EHS_type;

/* The global handler stack.  */
tree EHS_decl;

/* Cached component refs to fields of `EHS_decl'.  */
static tree EHS_prev, EHS_handler, EHS_parms, EHS_name;
static rtx EHS_parms_as_rtx, EHS_name_as_rtx;

/* The parameter names of this exception type.  */

static tree last_exception_fields;
static tree last_exception_field_types;

/* When ID is VOID_TYPE_NODE, it means ``raise all''.
   Cannot be inline, since it uses `alloca', and that
   breaks code which pushes the result of this function
   on the stack.  */
static tree
exception_object_name (prefix, id)
     tree prefix;
     tree id;
{
  /* First, cons up the `name' of this exception.  */
  char *name;
  int length = (id == void_type_node ? 3 : IDENTIFIER_LENGTH (id)) + EXCEPTION_NAME_LENGTH;

  if (prefix)
    length += IDENTIFIER_LENGTH (prefix) + 2;

  name = (char *)alloca (length);
  strcpy (name, EXCEPTION_NAME_PREFIX);
  length = EXCEPTION_NAME_LENGTH;
  if (prefix)
    {
      strcpy (name + length, IDENTIFIER_POINTER (prefix));
#ifdef JOINER
      name[length + IDENTIFIER_LENGTH (prefix)] = JOINER;
#else
      name[length + IDENTIFIER_LENGTH (prefix)] = '_';
#endif
      length += IDENTIFIER_LENGTH (prefix) + 1;
    }
  if (id == void_type_node)
    strcpy (name + length, "all");
  else
    strcpy (name + length, IDENTIFIER_POINTER (id));
  return get_identifier (name);
}

tree
lookup_exception_cname (ctype, cname, raise_id)
     tree ctype, cname;
     tree raise_id;
{
  tree this_cname = TREE_PURPOSE (raise_id);
  if (this_cname == NULL_TREE)
    {
      if (cname)
	{
	  tree name = TREE_VALUE (raise_id);
	  if (purpose_member (name, CLASSTYPE_TAGS (ctype)))
	    this_cname = cname;
	}
    }
  else if (this_cname == void_type_node)
    this_cname = NULL_TREE;
  else if (TREE_CODE (this_cname) != IDENTIFIER_NODE)
    {
      sorry ("multiple scope refs in `cplus_expand_raise_stmt'");
      this_cname = error_mark_node;
    }
  return this_cname;
}

tree
lookup_exception_tname (oname)
     tree oname;
{
  return get_identifier (IDENTIFIER_POINTER (oname) + EXCEPTION_NAME_LENGTH);
}

tree
lookup_exception_object (cname, name, complain)
     tree cname, name;
     int complain;
{
  tree oname;
  tree decl;

  if (cname == void_type_node)
    cname = NULL_TREE;
  else if (cname && TREE_CODE (cname) != IDENTIFIER_NODE)
    {
      sorry ("multiple scope refs in `lookup_exception_object'");
      cname = NULL_TREE;
    }
  oname = exception_object_name (cname, name);
  decl = IDENTIFIER_GLOBAL_VALUE (oname);
  if (decl == NULL_TREE || TREE_CODE (decl) != VAR_DECL)
    {
      if (complain)
	{
	  push_obstacks_nochange ();

	  if (cname)
	    error ("no exception name object for name `%s::%s'",
		   IDENTIFIER_POINTER (cname),
		   IDENTIFIER_POINTER (name));
	  else
	    error ("no exception name object for name `%s'",
		   IDENTIFIER_POINTER (name));
	  end_temporary_allocation ();
	  /* Avoid further error messages.  */
	  pushdecl_top_level (build_lang_field_decl (VAR_DECL,
						     exception_object_name (cname, name),
						     error_mark_node));
	  pop_obstacks ();
	}
      return NULL_TREE;
    }
  return decl;
}

tree
lookup_exception_type (ctype, cname, raise_id)
     tree ctype, cname;
     tree raise_id;
{
  tree name = TREE_VALUE (raise_id);
  tree purpose = TREE_PURPOSE (raise_id);

  if (cname && purpose == NULL_TREE)
    purpose = cname;

  if (purpose && purpose != void_type_node)
    {
      tree link = NULL_TREE;

      if (TREE_CODE (purpose) != IDENTIFIER_NODE)
	{
	  sorry ("multiple scope refs in `lookup_exception_type'");
	  TREE_PURPOSE (raise_id) = NULL_TREE;
	  return NULL_TREE;
	}
      if (! is_aggr_typedef (purpose, 1))
	return NULL_TREE;
      ctype = IDENTIFIER_TYPE_VALUE (purpose);
      link = purpose_member (name, CLASSTYPE_TAGS (ctype));
      if (link)
	return TREE_VALUE (link);
    }

  ctype = lookup_name (name, 1);
  if (ctype && TREE_CODE (ctype) == TYPE_DECL)
    ctype = TREE_TYPE (ctype);
  if (ctype && TREE_CODE (ctype) == RECORD_TYPE
      && CLASSTYPE_DECLARED_EXCEPTION (ctype))
    return ctype;
  return NULL_TREE;
}

tree
finish_exception (e, list_of_fieldlists)
     tree e;
     tree list_of_fieldlists;
{
  tree parmtypes = NULL_TREE, name_field;
  tree cname = TYPE_NAME (e);

  if (TREE_CODE (cname) == TYPE_DECL)
    cname = DECL_NAME (cname);

  if (last_exception_fields)
    error ("cannot declare exceptions within exceptions");
  if (list_of_fieldlists && ! ANON_AGGRNAME_P (cname))
    error_with_aggr_type (e, "exception name `%s' must follow body declaration");
  if (list_of_fieldlists)
    {
      tree prev, field;

      /* Note: no public, private, or protected allowed.  */
      if (TREE_CHAIN (list_of_fieldlists))
	error ("visibility declarations invalid in exception declaration");
      else if (TREE_PURPOSE (list_of_fieldlists) != (tree)visibility_default)
	error ("visibility declarations invalid in exception declaration");
      TREE_PURPOSE (list_of_fieldlists) = (tree)visibility_default;

      /* Note also: no member function declarations allowed.  */
      for (prev = 0, field = TREE_VALUE (list_of_fieldlists);
	   field; prev = field, field = TREE_CHAIN (field))
	{
	  switch (TREE_CODE (field))
	    {
	    case FIELD_DECL:
	      /* ok.  */
	      parmtypes = tree_cons (NULL_TREE, TREE_TYPE (field), parmtypes);
	      continue;
	    case FUNCTION_DECL:
	      error_with_decl (field, "declaration of function `%s' in exception invalid");
	      break;
	    case VAR_DECL:
	      if (TREE_STATIC (field))
		error_with_decl (field, "declaration of static variable `%s' in exception invalid");
	      else
		error_with_decl (field, "declaration of constant field `%s' in exception invalid");
	      break;
	    case CONST_DECL:
	      error_with_decl (field, "declaration of enum value `%s' in exception invalid");
	      break;
	    case SCOPE_REF:
	      error ("use of `::' in exception context invalid");
	      break;
	    }
	  if (prev)
	    TREE_CHAIN (prev) = TREE_CHAIN (field);
	  else
	    TREE_VALUE (list_of_fieldlists) = TREE_CHAIN (field);
	}
    }

  /* Now that we've cleaned up the fields, add a name identifier at front.  */
  name_field = build_lang_field_decl (FIELD_DECL, get_identifier ("__name"),
				      ptr_type_node);
  if (list_of_fieldlists)
    {
      TREE_CHAIN (name_field) = TREE_VALUE (list_of_fieldlists);
      TREE_VALUE (list_of_fieldlists) = name_field;
    }
  else
    list_of_fieldlists = build_tree_list (NULL_TREE, name_field);

  last_exception_fields = TREE_VALUE (list_of_fieldlists);
  if (parmtypes)
    {
      last_exception_field_types = nreverse (parmtypes);
      /* Set the TREE_CHAIN of what is now at the end of the
	 list to `void_list_node'.  */
      TREE_CHAIN (parmtypes) = void_list_node;
    }
  else
    last_exception_field_types = void_list_node;

  popclass (0);

#if 0
  /* Remove aggregate types from the list of tags,
     since these appear at global scope.  */
  while (x && IS_AGGR_TYPE (TREE_VALUE (x)))
    x = TREE_CHAIN (x);
  CLASSTYPE_TAGS (t) = x;
  y = x;
  while (x)
    {
      if (IS_AGGR_TYPE (TREE_VALUE (x)))
	TREE_CHAIN (y) = TREE_CHAIN (x);
      x = TREE_CHAIN (x);
    }
#endif

  if (flag_cadillac)
    cadillac_finish_exception (e);

  return e;
}

void
finish_exception_decl (cname, decl)
     tree cname, decl;
{
  /* In cp-decl.h.  */
  extern tree last_function_parms;

  /* An exception declaration.  */
  tree t, ctor;
  tree parmdecls = NULL_TREE, fields;
  tree list_of_fieldlists = temp_tree_cons (NULL_TREE,
					    copy_list (last_exception_fields),
					    NULL_TREE);
  tree edecl = build_lang_field_decl (VAR_DECL,
				      exception_object_name (cname, DECL_NAME (decl)),
				      ptr_type_node);

  DECL_LANGUAGE (edecl) = lang_c;
  TREE_STATIC (edecl) = 1;
  TREE_PUBLIC (edecl) = 1;
  finish_decl (pushdecl (edecl), NULL_TREE, NULL_TREE, 0);

  /* Now instantiate the exception decl.  */
  t = xref_tag (exception_type_node, DECL_NAME (decl), NULL_TREE);

  /* finish_struct will pop this.  */
  pushclass (t, 0);

  /* Now add a constructor which takes as parameters all the types we
     just defined.  */
  ctor = build_lang_decl (FUNCTION_DECL, DECL_NAME (decl),
			  build_cplus_method_type (t, TYPE_POINTER_TO (t),
						   last_exception_field_types));
  /* Don't take `name'.  The constructor handles that.  */
  fields = TREE_CHAIN (TREE_VALUE (list_of_fieldlists));
  while (fields)
    {
      tree parm = build_decl (PARM_DECL, DECL_NAME (fields), TREE_TYPE (fields));
      /* Since there is a prototype, args are passed in their own types.  */
      DECL_ARG_TYPE (parm) = TREE_TYPE (parm);
#ifdef PROMOTE_PROTOTYPES
      if (TREE_CODE (TREE_TYPE (fields)) == INTEGER_TYPE
	  && TYPE_PRECISION (TREE_TYPE (fields)) < TYPE_PRECISION (integer_type_node))
	DECL_ARG_TYPE (parm) = integer_type_node;
#endif
      TREE_CHAIN (parm) = parmdecls;
      parmdecls = parm;
      fields = TREE_CHAIN (fields);
    }
  fields = TREE_VALUE (list_of_fieldlists);
  last_function_parms = nreverse (parmdecls);

  DECL_CONSTRUCTOR_P (ctor) = 1;
  TYPE_HAS_CONSTRUCTOR (t) = 1;
  grokclassfn (t, DECL_NAME (decl), ctor, NO_SPECIAL, NULL_TREE);
  DECL_EXTERNAL (ctor) = 1;
  TREE_STATIC (ctor) = 1;
  TREE_PUBLIC (ctor) = 0;
  DECL_INLINE (ctor) = 1;
  make_decl_rtl (ctor, NULL_PTR, 1);
  finish_decl (ctor, NULL_TREE, NULL_TREE, 0);
  TREE_CHAIN (ctor) = TREE_VALUE (list_of_fieldlists);
  TREE_VALUE (list_of_fieldlists) = ctor;

  finish_struct (t, list_of_fieldlists, 0);

  if (current_function_decl)
    error ("cannot define exception inside function scope");
  else
    {
      enum debug_info_type old_write_symbols = write_symbols;
      write_symbols = NO_DEBUG;

      /* Now build the constructor for this exception.  */
      parmdecls = DECL_ARGUMENTS (ctor);
      start_function (NULL_TREE, ctor, 0, 1);
      store_parm_decls ();
      pushlevel (0);
      clear_last_expr ();
      push_momentary ();
      expand_start_bindings (0);

      /* Move all the parameters to the fields, skipping `this'.  */
      parmdecls = TREE_CHAIN (parmdecls);
      /* Install `name' of this exception handler.  */
      DECL_INITIAL (fields) = build_unary_op (ADDR_EXPR, edecl, 0);
      fields = TREE_CHAIN (fields);
      /* Install all the values.  */
      while (fields)
	{
	  /* Set up the initialization for this field.  */
	  DECL_INITIAL (fields) = parmdecls;
	  fields = TREE_CHAIN (fields);
	  parmdecls = TREE_CHAIN (parmdecls);
	}
      emit_base_init (t, 0);

      finish_function (DECL_SOURCE_LINE (ctor), 1);
      write_symbols = old_write_symbols;
    }
}

void
end_exception_decls ()
{
  last_exception_field_types = NULL_TREE;
  last_exception_fields = NULL_TREE;
}
\f
/* Statement-level exception semantics.  */

void
cplus_expand_start_try (implicit)
     int implicit;
{
  tree call_to_setjmp;
  tree handler, ref;

  /* Start a new block enclosing the whole handler.  */
  if (implicit)
    {
      pushlevel_temporary (1);
    }
  else
    {
      pushlevel (0);
      clear_last_expr ();
      push_momentary ();

      /* Encompass whole exception handler in one big binding contour.
	 If RAISE should throw out of the whole TRY/EXCEPT block, call
	 `expand_start_bindings' with argument of 1.  */
      expand_start_bindings (0);
    }

  /* Allocate handler in that block.  It's real name will come later.
     Note that it will be the first name in this binding contour.  */
  handler = get_temp_name (EHS_type, 0);
  DECL_INITIAL (handler) = error_mark_node;
  finish_decl (handler, NULL_TREE, NULL_TREE, 0);

  /* Must come after call to `finish_decl', else the cleanup for the temp
     for the handler will cause the contour we just created to be popped.  */
  if (implicit)
    declare_implicit_exception ();

  /* Catch via `setjmp'.  */
  ref = build_component_ref (handler, get_identifier ("handler"), NULL_TREE, 0);
  call_to_setjmp = build_function_call (BISJ, build_tree_list (NULL_TREE, ref));

  /* RAISE throws to EXCEPT part.  */
  expand_start_try (build_binary_op (EQ_EXPR, call_to_setjmp, integer_zero_node, 1), 0, 1);
}

/* If KEEP is 1, then declarations in the TRY statement are worth keeping.
   If KEEP is 2, then the TRY statement was generated by the compiler.
   If KEEP is 0, the declarations in the TRY statement contain errors.  */

tree
cplus_expand_end_try (keep)
     int keep;
{
  tree decls, decl, block;

  if (keep < 2)
    pop_implicit_try_blocks (NULL_TREE);

  decls = getdecls ();

  /* Emit code to avoid falling through into a default
     handler that might come later.  */
  expand_end_try ();

  /* Pops binding contour local to TRY, and get the exception handler
     object built by `...start_try'.  */
  switch (keep)
    {
    case 0:
      expand_end_bindings (decls, 0, 1);
      block = poplevel (0, 0, 0);
      pop_momentary (); 
      decl = getdecls ();
      break;

    case 1:
      expand_end_bindings (decls, 1, 1);
      block = poplevel (1, 1, 0);
      pop_momentary ();
      decl = getdecls ();
      break;

    default:
      decl = tree_last (decls);
      block = NULL_TREE;
      break;
    }

  my_friendly_assert (TREE_CODE (decl) == VAR_DECL
		      && TREE_TYPE (decl) == EHS_type, 203);
  if (block)
    {
      BLOCK_HANDLER_BLOCK (block) = 1;
      TREE_USED (block) = 1;
    }

  /* Pass it back so that its rtl can be bound to its name
     (or vice versa).  */
  return decl;
}

void
cplus_expand_start_except (name, decl)
     tree name, decl;
{
  int yes;
  tree tmp, init;

  expand_start_except (0, 1);

  /* This is internal `eh'.  */
  current_exception_decl = decl;
  current_exception_name_as_rtx
    = expand_expr (build (COMPONENT_REF, ptr_type_node,
			  current_exception_decl, TREE_OPERAND (EHS_name, 1)),
		   0, 0, 0);
  init = build (COMPONENT_REF, ptr_type_node, decl, TREE_OPERAND (EHS_parms, 1));
  current_exception_parms_as_rtx = expand_expr (init, 0, 0, 0);

  if (name)
    {
      /* Get the exception object into scope (user declared `ex').  */
      tmp = pushdecl (build_decl (VAR_DECL, name, ptr_type_node));
      DECL_INITIAL (tmp) = error_mark_node;
      finish_decl (tmp, init, 0, 0);
    }
  current_exception_type = NULL_TREE;
  yes = suspend_momentary ();
  if (name)
    {
      /* From now on, send the user to our faked-up object.  */
      current_exception_object = build1 (INDIRECT_REF, void_type_node, tmp);
      IDENTIFIER_LOCAL_VALUE (name) = current_exception_object;
    }
  resume_momentary (yes);

  /* Pop exception handler stack.  */
  expand_assignment (EHS_decl, EHS_prev, 0, 0);
}

/* Generate the call to `unhandled_exception' that is appropriate
   for this particular unhandled exception.  */
static tree
call_to_unhandled_exception ()
{
  extern int lineno;
  extern tree combine_strings ();
  tree parms = tree_cons (NULL_TREE,
			  combine_strings (build_string (strlen (input_filename + 1), input_filename)),
			  build_tree_list (NULL_TREE, build_int_2 (lineno, 0)));
  return build_function_call (BIUE, parms);
}

/* Note that this must be mirror image of `...start_try'.
   DFAULT is the default clause, if there was one.
   DFAULT is ERROR_MARK_NODE when this ends an implicit handler.  */
void
cplus_expand_end_except (dfault)
     tree dfault;
{
  extern tree expand_end_except (); /* stmt.c.  */
  tree decls, raised;

  if (dfault == NULL_TREE)
    {
      /* Uncaught exception at outermost level.  If raised locally,
	 reraise the exception.  Otherwise, generate code to call `abort'.  */
      if (in_try_block (1) == 0)
	{
	  expand_start_cond (build (EQ_EXPR, integer_type_node,
				    exception_throw_decl, integer_zero_node), 0);
	  expand_expr (call_to_unhandled_exception (), 0, VOIDmode, 0);
	  expand_end_cond ();
	}
      /* Try the next handler.  */
      if (! expand_escape_except ())
	compiler_error ("except nesting botch");
    }

  raised = expand_end_except ();

  decls = getdecls ();
  expand_end_bindings (decls, decls != 0, 1);
  poplevel (decls != 0, 1, 0);

  /* Implicit handlers do not use the momentary obstack.  */
  if (dfault != error_mark_node)
    pop_momentary ();

  if (! in_try_block (1))
    {
      /* Check that this function is not raising exceptions
	 it is not supposed to.  */
      while (raised)
	{
	  error_with_decl (TREE_VALUE (raised), "exception `%s' raised but not declared raisable");
	  raised = TREE_CHAIN (raised);
	}
    }
  else if (dfault == NULL_TREE || dfault == error_mark_node)
    {
      expand_start_cond (build (NE_EXPR, integer_type_node,
				exception_throw_decl,
				integer_zero_node), 0);
      /* We fell off the end of this try block.  Try going to the next.
	 The escape_label will be the beginning of the next try block.  */
      if (! expand_escape_except ())
	compiler_error ("except nesting botch");
      expand_end_cond ();
    }
}

/* Generate code to raise exception RAISE_ID.
   If EXP is NULL_TREE, then PARMS is the list of parameters to use
   for constructing this exception.
   If EXP is non-NULL, then it is an already constructed object
   of the kind that we want.

   FOR_RERAISE is non-zero if this raise is called by reraise.  In
   this case we do not need to emit extra gotos to avoid warning messages;
   the caller will do that once after all the exceptions it reraises
   are handled and raised.  */
void
cplus_expand_raise (raise_id, parms, exp, for_reraise)
     tree raise_id;
     tree parms;
     tree exp;
     int for_reraise;
{
  /* Allocate new exception of appropriate type, passing
     PARMS to its constructor.  */
  tree cname, name;
  tree decl;
  tree xexp = exp;

  cname = lookup_exception_cname (current_class_type, current_class_name, raise_id);
  if (cname == error_mark_node)
    return;
  name = TREE_VALUE (raise_id);

  decl = lookup_exception_object (cname, name, 1);
  if (decl == NULL_TREE)
    return;

  if (exp == NULL_TREE)
    {
      exp = build_method_call (NULL_TREE, name, parms, NULL_TREE, LOOKUP_COMPLAIN);
      if (exp == error_mark_node)
	return;
    }

  if (in_try_block (1))
    {
      expand_raise (decl);
    }
  else if (! current_function_decl)
    {
      if (xexp == NULL_TREE)
	error_with_decl (decl, "invalid raise of `%s' outside of functions");
      else
	error_with_decl (decl, "invalid reraise of `%s' outside of functions");
    }
  else
    {
      /* Test this raise against what this function permits.  */
      tree names = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (current_function_decl));
      while (names)
	{
	  if (decl == TREE_TYPE (names))
	    break;
	  names = TREE_CHAIN (names);
	}
      if (names == NULL_TREE)
	{
	  error ("current function not declared to raise exception `%s'",
		 IDENTIFIER_POINTER (name));
	  return;
	}
    }

  store_expr (exp, EHS_parms_as_rtx, 0);

  /* Set the global exception handler stack's NAME field
     to the `name' of this exception.  The global exception
     handler stack is the container for the exception object
     we just built.

     We go through a function call to make life easier when debugging.  */
#if 0
  expand_assignment (EHS_name, build_unary_op (ADDR_EXPR, decl, 0), 0, 0);
#else
  parms = tree_cons (NULL_TREE, build_unary_op (ADDR_EXPR, EHS_name, 0),
		     build_tree_list (NULL_TREE,
				      build_unary_op (ADDR_EXPR, decl, 0)));
  expand_expr (build_function_call (BIR, parms), 0, 0, 0);
#endif

  /* Activate thrower.  If we are inside a TRY statement,
     we can cheat and not do this, saving a longjmp.  */
  if (in_try_block (1) == 0)
    {
      sets_exception_throw_decl = 1;
      emit_move_insn (DECL_RTL (exception_throw_decl), const1_rtx);
    }

  if (xexp == NULL_TREE)
    {    
      /* Invoke destructors for current procedure or handler.  */
      if (! expand_escape_except ())
	compiler_error ("except nesting botch");
      /* Throw via `longjmp'... Done as side-effect of goto.  */
    }
  /* To avoid spurious warning messages, we add a goto to the end
     of the function.  This code is dead, and the compiler should
     know how to delete it, but for now, we are stuck with it.  */
  if (! for_reraise
      && TREE_TYPE (DECL_RESULT (current_function_decl)) != void_type_node)
    expand_null_return ();
}

extern tree cplus_exception_name ();

tree
ansi_exception_object_lookup (type)
     tree type;
{
  tree raise_id = cplus_exception_name (type);
  tree decl;

  decl = IDENTIFIER_GLOBAL_VALUE (raise_id);
  if (decl == NULL_TREE || TREE_CODE (decl) != VAR_DECL)
    {
      push_obstacks_nochange ();
      end_temporary_allocation ();
      decl = build_decl (VAR_DECL, raise_id, ptr_type_node);
      TREE_PUBLIC (decl) = 1;
      TREE_STATIC (decl) = 1;
      pushdecl_top_level (decl);
      make_decl_rtl (decl, (char*)0, 1);
      pop_obstacks ();
    }
  return decl;
}

/* Generate code to throw an exception using EXP.
   Usng ANSI syntax and semantics.
   If EXP is NULL_TREE< re-raise instead. */

void
cplus_expand_throw (exp)
     tree exp;
{
  tree parms;
  int for_reraise;
  /* Allocate new exception of appropriate type, passing
     PARMS to its constructor.  */
  tree decl = ansi_exception_object_lookup (TREE_TYPE (exp));
  tree xexp = exp;

  if (in_try_block (1))
    {
#if 1
      my_friendly_abort (35);
#else
      expand_raise (decl);
#endif
    }
  else if (! current_function_decl)
    error ("invalid throw outside of functions");
  else
    {
#if 0
      /* Test this raise against what this function permits.  */
      tree names = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (current_function_decl));
      while (names)
	{
	  if (decl == TREE_TYPE (names))
	    break;
	  names = TREE_CHAIN (names);
	}
      if (names == NULL_TREE)
	{
	  error ("current function not declared to raise exception `%s'",
		 IDENTIFIER_POINTER (name));
	  return;
	}
#endif
    }

  store_expr (exp, EHS_parms_as_rtx, 0);

  /* Set the global exception handler stack's NAME field
     to the `name' of this exception.  The global exception
     handler stack is the container for the exception object
     we just built.

     We go through a function call to make life easier when debugging.  */
#if 0
  expand_assignment (EHS_name, build_unary_op (ADDR_EXPR, decl, 0), 0, 0);
#else
  parms = tree_cons (NULL_TREE, build_unary_op (ADDR_EXPR, EHS_name, 0),
		     build_tree_list (NULL_TREE,
				      build_unary_op (ADDR_EXPR, decl, 0)));
  expand_expr (build_function_call (BIR, parms), 0, 0, 0);
#endif

  /* Activate thrower.  If we are inside a TRY statement,
     we can cheat and not do this, saving a longjmp.  */
  if (in_try_block (1) == 0)
    {
      sets_exception_throw_decl = 1;
      emit_move_insn (DECL_RTL (exception_throw_decl), const1_rtx);
    }

  if (xexp == NULL_TREE)
    {    
      /* Invoke destructors for current procedure or handler.  */
      if (! expand_escape_except ())
	compiler_error ("except nesting botch");
      /* Throw via `longjmp'... Done as side-effect of goto.  */
    }

  /* XXX: for_reraise is never set above here.  */
  /* To avoid spurious warning messages, we add a goto to the end
     of the function.  This code is dead, and the compiler should
     know how to delete it, but for now, we are stuck with it.  */
  if (! for_reraise
      && TREE_TYPE (DECL_RESULT (current_function_decl)) != void_type_node)
    expand_null_return ();
}

tree
cplus_expand_start_catch (raise_id)
     tree raise_id;
{
  tree cname = lookup_exception_cname (current_class_type, current_class_name, raise_id);
  tree decl;
  tree cond;

  if (cname == error_mark_node)
    {
      decl = error_mark_node;
      cond = error_mark_node;
    }
  else
    {
      decl = lookup_exception_object (cname, TREE_VALUE (raise_id), 1);
      if (decl == NULL_TREE)
	cond = error_mark_node;
      else
	cond = build_binary_op (EQ_EXPR, build_unary_op (ADDR_EXPR, decl, 0),
				build (COMPONENT_REF, ptr_type_node,
				       current_exception_decl,
				       TREE_OPERAND (EHS_name, 1)),
				1);
    }
  expand_start_cond (cond, 0);

  /* Does nothing right now.  */
  expand_catch (decl);
  if (current_exception_type
      && TYPE_NEEDS_DESTRUCTOR (current_exception_type))
    {
      /* Make a cleanup for the name-specific exception object now in scope.  */
      tree cleanup = maybe_build_cleanup (current_exception_object);
      expand_start_bindings (0);
      expand_decl_cleanup (NULL_TREE, cleanup);
    }
  return decl;
}
tree
ansi_expand_start_catch (raise_type)
     tree raise_type;
{
  tree decl = ansi_exception_object_lookup (raise_type);
  tree cond;

  if (decl == NULL_TREE)
      cond = error_mark_node;
  else
      cond = build_binary_op (EQ_EXPR, build_unary_op (ADDR_EXPR, decl, 0),
			      build (COMPONENT_REF, ptr_type_node,
				     current_exception_decl,
				     TREE_OPERAND (EHS_name, 1)),
			      1);
  expand_start_cond (cond, 0);

  /* Does nothing right now.  */
  expand_catch (decl);
  return decl;
}

void
cplus_expand_end_catch (for_reraise)
     int for_reraise;
{
  if (current_exception_type
      && TYPE_NEEDS_DESTRUCTOR (current_exception_type))
    {
      /* Destroy the specific exception object now in scope.  */
      expand_end_bindings (getdecls (), 0, 1);
    }
  if (for_reraise)
    {
      if (! expand_escape_except ())
	my_friendly_abort (36);
    }
  else
    {
      if (! expand_end_catch ())
	my_friendly_abort (37);
    }
  expand_end_cond ();
}

/* Reraise an exception.
   If EXCEPTIONS is NULL_TREE, it means reraise whatever exception was caught.
   If EXCEPTIONS is an IDENTIFIER_NODE, it means reraise the exception
   object named by EXCEPTIONS.  This must be a variable declared in
   an `except' clause.
   If EXCEPTIONS is a TREE_LIST, it is the list of exceptions we are
   willing to reraise.  */

void
cplus_expand_reraise (exceptions)
     tree exceptions;
{
  tree ex_ptr;
  tree ex_object = current_exception_object;
  rtx ex_ptr_as_rtx;

  if (exceptions && TREE_CODE (exceptions) == IDENTIFIER_NODE)
    {
      /* Don't get tripped up if its TREE_TYPE is `error_mark_node'.  */
      ex_object = IDENTIFIER_LOCAL_VALUE (exceptions);
      if (ex_object == NULL_TREE || TREE_CODE (ex_object) != INDIRECT_REF)
	{
	  error ("`%s' is not an exception decl", IDENTIFIER_POINTER (exceptions));
	  return;
	}
      my_friendly_assert (TREE_CODE (TREE_OPERAND (ex_object, 0)) == VAR_DECL,
			  204);
      exceptions = NULL_TREE;
    }

  ex_ptr = build1 (NOP_EXPR, ptr_type_node, TREE_OPERAND (ex_object, 0));
  ex_ptr_as_rtx = expand_expr (ex_ptr, 0, 0, 0);

  /* reraise ALL, used by compiler.  */
  if (exceptions == NULL_TREE)
    {
      /* Now treat reraise like catch/raise.  */
      expand_catch (error_mark_node);
      expand_raise (error_mark_node);
      emit_move_insn (EHS_name_as_rtx, current_exception_name_as_rtx);
      store_expr ((tree) EHS_parms_as_rtx, current_exception_parms_as_rtx, 0);
      if (in_try_block (1) == 0)
	{
	  sets_exception_throw_decl = 1;
	  emit_move_insn (DECL_RTL (exception_throw_decl), const1_rtx);
	}
      /* Set to zero so that destructor will not be called.  */
      emit_move_insn (ex_ptr_as_rtx, const0_rtx);
      if (! expand_escape_except ())
	my_friendly_abort (38);

      /* To avoid spurious warning messages, we add a goto to the end
	 of the function.  This code is dead, and the compiler should
	 know how to delete it, but for now, we are stuck with it.  */
      if (TREE_TYPE (DECL_RESULT (current_function_decl)) != void_type_node)
	expand_null_return ();

      return;
    }

  /* reraise from a list of exceptions.  */
  while (exceptions)
    {
      tree type = lookup_exception_type (current_class_type, current_class_name,
					 exceptions);
      if (type == NULL_TREE)
	{
	  error ("`%s' is not an exception type",
		 IDENTIFIER_POINTER (TREE_VALUE (exceptions)));
	  current_exception_type = NULL_TREE;
	  TREE_TYPE (ex_object) = error_mark_node;
	  TREE_TYPE (ex_ptr) = error_mark_node;
	}
      else
	{
	  current_exception_type = type;
	  /* In-place union.  */
	  TREE_TYPE (ex_object) = type;
	  TREE_TYPE (ex_ptr) = TYPE_POINTER_TO (type);
	}

      /* Now treat reraise like catch/raise.  */
      cplus_expand_start_catch (exceptions);
      cplus_expand_raise (exceptions, NULL_TREE, ex_ptr, 1);
      /* Set to zero so that destructor will not be called.  */
      if (TREE_TYPE (ex_ptr) != error_mark_node)
	emit_move_insn (ex_ptr_as_rtx, const0_rtx);
      cplus_expand_end_catch (1);
      exceptions = TREE_CHAIN (exceptions);
    }
  /* Don't propagate any unhandled exceptions.  */
  expand_expr (call_to_unhandled_exception (), 0, VOIDmode, 0);

  /* To avoid spurious warning messages, we add a goto to the end
     of the function.  This code is dead, and the compiler should
     know how to delete it, but for now, we are stuck with it.  */
  if (TREE_TYPE (DECL_RESULT (current_function_decl)) != void_type_node)
    expand_null_return ();
}
\f
void
setup_exception_throw_decl ()
{
  tree call_to_longjmp, parms;

  int old = suspend_momentary ();

  exception_throw_decl = build_decl (VAR_DECL, get_identifier (THROW_NAME), integer_type_node);
  pushdecl (exception_throw_decl);
  parms = tree_cons (NULL_TREE, EHS_handler,
		     build_tree_list (0, integer_one_node));
  call_to_longjmp = build_function_call (BILJ, parms);

  expand_decl (exception_throw_decl);
  expand_decl_cleanup (exception_throw_decl,
		       build (COND_EXPR, void_type_node,
			      exception_throw_decl,
			      call_to_longjmp, integer_zero_node));
  DECL_INITIAL (exception_throw_decl) = integer_zero_node;
  sets_exception_throw_decl = 0;
  resume_momentary (old);

  /* Cache these, since they won't change throughout the function.  */
  EHS_parms_as_rtx = expand_expr (EHS_parms, 0, 0, 0);
  EHS_name_as_rtx = expand_expr (EHS_name, 0, 0, 0);
}

void
init_exception_processing ()
{
  extern tree build_function_type (), define_function ();
  extern tree unhandled_exception_fndecl;
  tree cname = get_identifier ("ExceptionHandler");
  tree field, chain;
  tree ctor, dtor;
  tree jmp_buf_type = build_array_type (integer_type_node,
					build_index_type (build_int_2 (_JBLEN-1, 0)));
  tree jmp_buf_arg_type = build_pointer_type (integer_type_node);

  tree parmtypes = hash_tree_chain (jmp_buf_arg_type, void_list_node);
  tree setjmp_fndecl, longjmp_fndecl, raise_fndecl;

  int old_interface_only = interface_only;
  int old_interface_unknown = interface_unknown;
  interface_only = 1;
  interface_unknown = 0;
  EHS_type = xref_tag (record_type_node, cname, NULL_TREE);
  push_lang_context (lang_name_c);
  setjmp_fndecl = define_function ("setjmp",
				   build_function_type (integer_type_node,
							parmtypes),
				   NOT_BUILT_IN, pushdecl, 0);
  BISJ = default_conversion (setjmp_fndecl);
  parmtypes = hash_tree_chain (jmp_buf_arg_type,
			       hash_tree_chain (integer_type_node, void_list_node));
  longjmp_fndecl = define_function ("longjmp",
				    build_function_type (void_type_node, parmtypes),
				    NOT_BUILT_IN, pushdecl, 0);
  raise_fndecl = define_function ("__raise_exception",
				  build_function_type (void_type_node,
						       hash_tree_chain (ptr_type_node,
									hash_tree_chain (build_pointer_type (ptr_type_node), void_list_node))),
				  NOT_BUILT_IN, pushdecl, 0);
  BILJ = default_conversion (longjmp_fndecl);
  BIR = default_conversion (raise_fndecl);
  BIUE = default_conversion (unhandled_exception_fndecl);

  pop_lang_context ();

  /* finish_struct will pop this.  */
  pushclass (EHS_type, 0);
  field = build_lang_field_decl (FIELD_DECL, get_identifier ("parms"), ptr_type_node);
  chain = field;
  field = build_lang_field_decl (FIELD_DECL, get_identifier ("name"),
				 build_pointer_type (default_function_type));
  TREE_CHAIN (field) = chain;
  chain = field;
  field = build_lang_field_decl (FIELD_DECL, get_identifier ("handler"), jmp_buf_type);
  TREE_CHAIN (field) = chain;
  chain = field;
  field = build_lang_field_decl (FIELD_DECL, get_identifier ("prev"),
				 TYPE_POINTER_TO (EHS_type));
  TREE_CHAIN (field) = chain;
  chain = field;

  ctor = build_lang_decl (FUNCTION_DECL, cname,
			  build_cplus_method_type (EHS_type, TYPE_POINTER_TO (EHS_type), void_list_node));
  DECL_CONSTRUCTOR_P (ctor) = 1;
  TREE_STATIC (ctor) = 1;
  TREE_PUBLIC (ctor) = 1;
  DECL_EXTERNAL (ctor) = 1;
  grokclassfn (EHS_type, cname, ctor, NO_SPECIAL, 0);
  grok_ctor_properties (EHS_type, ctor);
  finish_decl (pushdecl (ctor), NULL_TREE, NULL_TREE, 0);
  /* Must copy the node here because the FUNCTION_DECL
     used inside the struct ain't the same as the
     FUNCTION_DECL we stick into the global binding
     contour.  */
  ctor = copy_node (ctor);
  TREE_CHAIN (ctor) = chain;
  chain = ctor;
  dtor = build_lang_decl (FUNCTION_DECL, cname,
			  build_cplus_method_type (EHS_type, TYPE_POINTER_TO (EHS_type), void_list_node));
  TREE_STATIC (dtor) = 1;
  TREE_PUBLIC (dtor) = 1;
  DECL_EXTERNAL (dtor) = 1;
  grokclassfn (EHS_type, cname, dtor, DTOR_FLAG, 0);
  finish_decl (pushdecl (dtor), NULL_TREE, NULL_TREE, 0);
  /* Copy for the same reason as copying ctor.  */
  dtor = copy_node (dtor);
  TREE_CHAIN (dtor) = chain;
  chain = dtor;
  TYPE_HAS_CONSTRUCTOR (EHS_type) = 1;
  TYPE_HAS_DESTRUCTOR (EHS_type) = 1;
  finish_struct (EHS_type, temp_tree_cons (NULL_TREE, chain, NULL_TREE), 0);
  interface_only = old_interface_only;
  interface_unknown = old_interface_unknown;
}

void
init_exception_processing_1 ()
{
  register tree EHS_id = get_identifier ("exceptionHandlerStack");

  EHS_decl = IDENTIFIER_GLOBAL_VALUE (EHS_id);

  /* If we have no other definition, default to library implementation.  */
  if (EHS_decl == NULL_TREE)
    {
      EHS_decl = build_decl (VAR_DECL, EHS_id, TYPE_POINTER_TO (EHS_type));
      /* If we don't push this, its definition, should it be encountered,
	 will not be seen.  */
      EHS_decl = pushdecl (EHS_decl);
      DECL_EXTERNAL (EHS_decl) = 1;
      TREE_STATIC (EHS_decl) = 1;
      TREE_PUBLIC (EHS_decl) = 1;
      finish_decl (EHS_decl, NULL_TREE, NULL_TREE, 0);
    }
  else if (TREE_CODE (EHS_decl) != VAR_DECL
	   || TREE_TYPE (EHS_decl) != TYPE_POINTER_TO (EHS_type))
    fatal ("exception handling declarations conflict with compiler's internal model");

  if (EHS_prev == NULL_TREE)
    {
      register tree EHS_DECL = build1 (INDIRECT_REF, EHS_type, EHS_decl);
      EHS_prev = build_component_ref (EHS_DECL, get_identifier ("prev"), 0, 0);
      EHS_handler = build_component_ref (EHS_DECL, get_identifier ("handler"), 0, 0);
      EHS_parms = build_component_ref (EHS_DECL, get_identifier ("parms"), 0, 0);
      EHS_name = build_component_ref (EHS_DECL, get_identifier ("name"), 0, 0);
    }
}