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/* GNU Objective C Runtime message lookup

   Copyright (C) 1993, 1995, 1996, 1997, 1998,

   2001, 2002, 2004 Free Software Foundation, Inc.

   Contributed by Kresten Krab Thorup

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 2, 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 COPYING.  If not, write to the Free Software

Foundation, 51 Franklin Street, Fifth Floor,

Boston, MA 02110-1301, USA.  */

/* As a special exception, if you link this library with files compiled with

   GCC to produce an executable, this does not cause the resulting executable

   to be covered by the GNU General Public License. This exception does not

   however invalidate any other reasons why the executable file might be

   covered by the GNU General Public License.  */

/* FIXME: This file has no business including tm.h.  */

/* FIXME: This should be using libffi instead of __builtin_apply

   and friends.  */

#include "tconfig.h"

#include "coretypes.h"

#include "tm.h"

#include "objc/runtime.h"

#include "objc/sarray.h"

#include "objc/encoding.h"

#include "runtime-info.h"

/* This is how we hack STRUCT_VALUE to be 1 or 0.   */

#define gen_rtx(args...) 1

#define gen_rtx_MEM(args...) 1

#define gen_rtx_REG(args...) 1

#define rtx int

#if ! defined (STRUCT_VALUE) || STRUCT_VALUE == 0

#define INVISIBLE_STRUCT_RETURN 1

#else

#define INVISIBLE_STRUCT_RETURN 0

#endif

/* The uninstalled dispatch table */

struct sarray *__objc_uninstalled_dtable = 0;   /* !T:MUTEX */

/* Hook for method forwarding. If it is set, is invoked to return a

   function that performs the real forwarding. Otherwise the libgcc

   based functions (__builtin_apply and friends) are used. */

IMP (*__objc_msg_forward) (SEL) = NULL;

/* Send +initialize to class */

static void __objc_send_initialize (Class);

static void __objc_install_dispatch_table_for_class (Class);

/* Forward declare some functions */

static void __objc_init_install_dtable (id, SEL);

/* Various forwarding functions that are used based upon the

   return type for the selector.

   __objc_block_forward for structures.

   __objc_double_forward for floats/doubles.

   __objc_word_forward for pointers or types that fit in registers.

   */

static double __objc_double_forward (id, SEL, ...);

static id __objc_word_forward (id, SEL, ...);

typedef struct { id many[8]; } __big;

#if INVISIBLE_STRUCT_RETURN 

static __big

#else

static id

#endif

__objc_block_forward (id, SEL, ...);

static Method_t search_for_method_in_hierarchy (Class class, SEL sel);

Method_t search_for_method_in_list (MethodList_t list, SEL op);

id nil_method (id, SEL);

/* Given a selector, return the proper forwarding implementation. */

inline

IMP

__objc_get_forward_imp (SEL sel)

{

  /* If a custom forwarding hook was registered, try getting a forwarding

   * function from it.  */

  if (__objc_msg_forward)

    {

      IMP result;

      if ((result = __objc_msg_forward (sel)) != NULL)

        return result;

    }

  /* In all other cases, use the default forwarding functions built using

   * __builtin_apply and friends.  */

    {

      const char *t = sel->sel_types;

      if (t && (*t == '[' || *t == '(' || *t == '{')

#ifdef OBJC_MAX_STRUCT_BY_VALUE

          && objc_sizeof_type (t) > OBJC_MAX_STRUCT_BY_VALUE

#endif

          )

        return (IMP)__objc_block_forward;

      else if (t && (*t == 'f' || *t == 'd'))

        return (IMP)__objc_double_forward;

      else

        return (IMP)__objc_word_forward;

    }

}

/* Given a class and selector, return the selector's implementation.  */

inline

IMP

get_imp (Class class, SEL sel)

{

  /* In a vanilla implementation we would first check if the dispatch

     table is installed.  Here instead, to get more speed in the

     standard case (that the dispatch table is installed) we first try

     to get the imp using brute force.  Only if that fails, we do what

     we should have been doing from the very beginning, that is, check

     if the dispatch table needs to be installed, install it if it's

     not installed, and retrieve the imp from the table if it's

     installed.  */

  void *res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);

  if (res == 0)

    {

      /* Not a valid method */

      if (class->dtable == __objc_uninstalled_dtable)

        {

          /* The dispatch table needs to be installed. */

          objc_mutex_lock (__objc_runtime_mutex);

           /* Double-checked locking pattern: Check

              __objc_uninstalled_dtable again in case another thread

              installed the dtable while we were waiting for the lock

              to be released.  */

         if (class->dtable == __objc_uninstalled_dtable)

           {

             __objc_install_dispatch_table_for_class (class);

           }

          objc_mutex_unlock (__objc_runtime_mutex);

          /* Call ourselves with the installed dispatch table

             and get the real method */

          res = get_imp (class, sel);

        }

      else

        {

          /* The dispatch table has been installed.  */

         /* Get the method from the dispatch table (we try to get it

            again in case another thread has installed the dtable just

            after we invoked sarray_get_safe, but before we checked

            class->dtable == __objc_uninstalled_dtable).

         */

          res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);

          if (res == 0)

            {

              /* The dispatch table has been installed, and the method

                 is not in the dispatch table.  So the method just

                 doesn't exist for the class.  Return the forwarding

                 implementation. */

              res = __objc_get_forward_imp (sel);

            }

        }

    }

  return res;

}

/* Query if an object can respond to a selector, returns YES if the

object implements the selector otherwise NO.  Does not check if the

method can be forwarded. */

inline

BOOL

__objc_responds_to (id object, SEL sel)

{

  void *res;

  /* Install dispatch table if need be */

  if (object->class_pointer->dtable == __objc_uninstalled_dtable)

    {

      objc_mutex_lock (__objc_runtime_mutex);

      if (object->class_pointer->dtable == __objc_uninstalled_dtable)

        {

          __objc_install_dispatch_table_for_class (object->class_pointer);

        }

      objc_mutex_unlock (__objc_runtime_mutex);

    }

  /* Get the method from the dispatch table */

  res = sarray_get_safe (object->class_pointer->dtable, (size_t) sel->sel_id);

  return (res != 0);

}

/* This is the lookup function.  All entries in the table are either a

   valid method *or* zero.  If zero then either the dispatch table

   needs to be installed or it doesn't exist and forwarding is attempted. */

inline

IMP

objc_msg_lookup (id receiver, SEL op)

{

  IMP result;

  if (receiver)

    {

      result = sarray_get_safe (receiver->class_pointer->dtable,

                                (sidx)op->sel_id);

      if (result == 0)

        {

          /* Not a valid method */

          if (receiver->class_pointer->dtable == __objc_uninstalled_dtable)

            {

              /* The dispatch table needs to be installed.

                 This happens on the very first method call to the class. */

              __objc_init_install_dtable (receiver, op);

              /* Get real method for this in newly installed dtable */

              result = get_imp (receiver->class_pointer, op);

            }

          else

            {

              /* The dispatch table has been installed.  Check again

                 if the method exists (just in case the dispatch table

                 has been installed by another thread after we did the

                 previous check that the method exists).

              */

              result = sarray_get_safe (receiver->class_pointer->dtable,

                                        (sidx)op->sel_id);

              if (result == 0)

                {

                  /* If the method still just doesn't exist for the

                     class, attempt to forward the method. */

                  result = __objc_get_forward_imp (op);

                }

            }

        }

      return result;

    }

  else

    return (IMP)nil_method;

}

IMP

objc_msg_lookup_super (Super_t super, SEL sel)

{

  if (super->self)

    return get_imp (super->class, sel);

  else

    return (IMP)nil_method;

}

int method_get_sizeof_arguments (Method *);

retval_t

objc_msg_sendv (id object, SEL op, arglist_t arg_frame)

{

  Method *m = class_get_instance_method (object->class_pointer, op);

  const char *type;

  *((id *) method_get_first_argument (m, arg_frame, &type)) = object;

  *((SEL *) method_get_next_argument (arg_frame, &type)) = op;

  return __builtin_apply ((apply_t) m->method_imp,

                          arg_frame,

                          method_get_sizeof_arguments (m));

}

void

__objc_init_dispatch_tables ()

{

  __objc_uninstalled_dtable = sarray_new (200, 0);

}

/* This function is called by objc_msg_lookup when the

   dispatch table needs to be installed; thus it is called once

   for each class, namely when the very first message is sent to it. */

static void

__objc_init_install_dtable (id receiver, SEL op __attribute__ ((__unused__)))

{

  objc_mutex_lock (__objc_runtime_mutex);

  /* This may happen, if the programmer has taken the address of a

     method before the dtable was initialized... too bad for him! */

  if (receiver->class_pointer->dtable != __objc_uninstalled_dtable)

    {

      objc_mutex_unlock (__objc_runtime_mutex);

      return;

    }

  if (CLS_ISCLASS (receiver->class_pointer))

    {

      /* receiver is an ordinary object */

      assert (CLS_ISCLASS (receiver->class_pointer));

      /* install instance methods table */

      __objc_install_dispatch_table_for_class (receiver->class_pointer);

      /* call +initialize -- this will in turn install the factory

         dispatch table if not already done :-) */

      __objc_send_initialize (receiver->class_pointer);

    }

  else

    {

      /* receiver is a class object */

      assert (CLS_ISCLASS ((Class)receiver));

      assert (CLS_ISMETA (receiver->class_pointer));

      /* Install real dtable for factory methods */

      __objc_install_dispatch_table_for_class (receiver->class_pointer);

      __objc_send_initialize ((Class)receiver);

    }

  objc_mutex_unlock (__objc_runtime_mutex);

}

/* Install dummy table for class which causes the first message to

   that class (or instances hereof) to be initialized properly */

void

__objc_install_premature_dtable (Class class)

{

  assert (__objc_uninstalled_dtable);

  class->dtable = __objc_uninstalled_dtable;

}

/* Send +initialize to class if not already done */

static void

__objc_send_initialize (Class class)

{

  /* This *must* be a class object */

  assert (CLS_ISCLASS (class));

  assert (! CLS_ISMETA (class));

  if (! CLS_ISINITIALIZED (class))

    {

      CLS_SETINITIALIZED (class);

      CLS_SETINITIALIZED (class->class_pointer);

      /* Create the garbage collector type memory description */

      __objc_generate_gc_type_description (class);

      if (class->super_class)

        __objc_send_initialize (class->super_class);

      {

        SEL          op = sel_register_name ("initialize");

        IMP          imp = 0;

        MethodList_t method_list = class->class_pointer->methods;

        while (method_list) {

          int i;

          Method_t method;

          for (i = 0; i < method_list->method_count; i++) {

            method = &(method_list->method_list[i]);

            if (method->method_name

                && method->method_name->sel_id == op->sel_id) {

              imp = method->method_imp;

              break;

            }

          }

          if (imp)

            break;

          method_list = method_list->method_next;

        }

        if (imp)

            (*imp) ((id) class, op);

      }

    }

}

/* Walk on the methods list of class and install the methods in the reverse

   order of the lists. Since methods added by categories are before the methods

   of class in the methods list, this allows categories to substitute methods

   declared in class. However if more than one category replaces the same

   method nothing is guaranteed about what method will be used.

   Assumes that __objc_runtime_mutex is locked down. */

static void

__objc_install_methods_in_dtable (Class class, MethodList_t method_list)

{

  int i;

  if (! method_list)

    return;

  if (method_list->method_next)

    __objc_install_methods_in_dtable (class, method_list->method_next);

  for (i = 0; i < method_list->method_count; i++)

    {

      Method_t method = &(method_list->method_list[i]);

      sarray_at_put_safe (class->dtable,

                          (sidx) method->method_name->sel_id,

                          method->method_imp);

    }

}

/* Assumes that __objc_runtime_mutex is locked down. */

static void

__objc_install_dispatch_table_for_class (Class class)

{

  Class super;

  /* If the class has not yet had its class links resolved, we must

     re-compute all class links */

  if (! CLS_ISRESOLV (class))

    __objc_resolve_class_links ();

  super = class->super_class;

  if (super != 0 && (super->dtable == __objc_uninstalled_dtable))

    __objc_install_dispatch_table_for_class (super);

  /* Allocate dtable if necessary */

  if (super == 0)

    {

      objc_mutex_lock (__objc_runtime_mutex);

      class->dtable = sarray_new (__objc_selector_max_index, 0);

      objc_mutex_unlock (__objc_runtime_mutex);

    }

  else

    class->dtable = sarray_lazy_copy (super->dtable);

  __objc_install_methods_in_dtable (class, class->methods);

}

void

__objc_update_dispatch_table_for_class (Class class)

{

  Class next;

  struct sarray *arr;

  /* not yet installed -- skip it */

  if (class->dtable == __objc_uninstalled_dtable)

    return;

  objc_mutex_lock (__objc_runtime_mutex);

  arr = class->dtable;

  __objc_install_premature_dtable (class); /* someone might require it... */

  sarray_free (arr);                       /* release memory */

  /* could have been lazy... */

  __objc_install_dispatch_table_for_class (class);

  if (class->subclass_list)     /* Traverse subclasses */

    for (next = class->subclass_list; next; next = next->sibling_class)

      __objc_update_dispatch_table_for_class (next);

  objc_mutex_unlock (__objc_runtime_mutex);

}

/* This function adds a method list to a class.  This function is

   typically called by another function specific to the run-time.  As

   such this function does not worry about thread safe issues.

   This one is only called for categories. Class objects have their

   methods installed right away, and their selectors are made into

   SEL's by the function __objc_register_selectors_from_class. */

void

class_add_method_list (Class class, MethodList_t list)

{

  /* Passing of a linked list is not allowed.  Do multiple calls.  */

  assert (! list->method_next);

  __objc_register_selectors_from_list(list);

  /* Add the methods to the class's method list.  */

  list->method_next = class->methods;

  class->methods = list;

  /* Update the dispatch table of class */

  __objc_update_dispatch_table_for_class (class);

}

Method_t

class_get_instance_method (Class class, SEL op)

{

  return search_for_method_in_hierarchy (class, op);

}

Method_t

class_get_class_method (MetaClass class, SEL op)

{

  return search_for_method_in_hierarchy (class, op);

}

/* Search for a method starting from the current class up its hierarchy.

   Return a pointer to the method's method structure if found.  NULL

   otherwise. */

static Method_t

search_for_method_in_hierarchy (Class cls, SEL sel)

{

  Method_t method = NULL;

  Class class;

  if (! sel_is_mapped (sel))

    return NULL;

  /* Scan the method list of the class.  If the method isn't found in the

     list then step to its super class. */

  for (class = cls; ((! method) && class); class = class->super_class)

    method = search_for_method_in_list (class->methods, sel);

  return method;

}

/* Given a linked list of method and a method's name.  Search for the named

   method's method structure.  Return a pointer to the method's method

   structure if found.  NULL otherwise. */

Method_t

search_for_method_in_list (MethodList_t list, SEL op)

{

  MethodList_t method_list = list;

  if (! sel_is_mapped (op))

    return NULL;

  /* If not found then we'll search the list.  */

  while (method_list)

    {

      int i;

      /* Search the method list.  */

      for (i = 0; i < method_list->method_count; ++i)

        {

          Method_t method = &method_list->method_list[i];

          if (method->method_name)

            if (method->method_name->sel_id == op->sel_id)

              return method;

        }

      /* The method wasn't found.  Follow the link to the next list of

         methods.  */

      method_list = method_list->method_next;

    }

  return NULL;

}

static retval_t __objc_forward (id object, SEL sel, arglist_t args);

/* Forwarding pointers/integers through the normal registers */

static id

__objc_word_forward (id rcv, SEL op, ...)

{

  void *args, *res;

  args = __builtin_apply_args ();

  res = __objc_forward (rcv, op, args);

  if (res)

    __builtin_return (res);

  else

    return res;

}

/* Specific routine for forwarding floats/double because of

   architectural differences on some processors.  i386s for

   example which uses a floating point stack versus general

   registers for floating point numbers.  This forward routine

   makes sure that GCC restores the proper return values */

static double

__objc_double_forward (id rcv, SEL op, ...)

{

  void *args, *res;

  args = __builtin_apply_args ();

  res = __objc_forward (rcv, op, args);

  __builtin_return (res);

}

#if INVISIBLE_STRUCT_RETURN

static __big

#else

static id

#endif

__objc_block_forward (id rcv, SEL op, ...)

{

  void *args, *res;

  args = __builtin_apply_args ();

  res = __objc_forward (rcv, op, args);

  if (res)

    __builtin_return (res);

  else

#if INVISIBLE_STRUCT_RETURN

    return (__big) {{0, 0, 0, 0, 0, 0, 0, 0}};

#else

    return nil;

#endif

}

/* This function is installed in the dispatch table for all methods which are

   not implemented.  Thus, it is called when a selector is not recognized. */

static retval_t

__objc_forward (id object, SEL sel, arglist_t args)

{

  IMP imp;

  static SEL frwd_sel = 0;                      /* !T:SAFE2 */

  SEL err_sel;

  /* first try if the object understands forward:: */

  if (! frwd_sel)

    frwd_sel = sel_get_any_uid ("forward::");

  if (__objc_responds_to (object, frwd_sel))

    {

      imp = get_imp (object->class_pointer, frwd_sel);

      return (*imp) (object, frwd_sel, sel, args);

    }

  /* If the object recognizes the doesNotRecognize: method then we're going

     to send it. */

  err_sel = sel_get_any_uid ("doesNotRecognize:");

  if (__objc_responds_to (object, err_sel))

    {

      imp = get_imp (object->class_pointer, err_sel);

      return (*imp) (object, err_sel, sel);

    }

  /* The object doesn't recognize the method.  Check for responding to

     error:.  If it does then sent it. */

  {

    char msg[256 + strlen ((const char *) sel_get_name (sel))

             + strlen ((const char *) object->class_pointer->name)];

    sprintf (msg, "(%s) %s does not recognize %s",

             (CLS_ISMETA (object->class_pointer)

              ? "class"

              : "instance" ),

             object->class_pointer->name, sel_get_name (sel));

    err_sel = sel_get_any_uid ("error:");

    if (__objc_responds_to (object, err_sel))

      {

        imp = get_imp (object->class_pointer, err_sel);

        return (*imp) (object, sel_get_any_uid ("error:"), msg);

      }

    /* The object doesn't respond to doesNotRecognize: or error:;  Therefore,

       a default action is taken. */

    objc_error (object, OBJC_ERR_UNIMPLEMENTED, "%s\n", msg);

    return 0;

  }

}

void

__objc_print_dtable_stats ()

{

  int total = 0;

  objc_mutex_lock (__objc_runtime_mutex);

#ifdef OBJC_SPARSE2

  printf ("memory usage: (%s)\n", "2-level sparse arrays");

#else

  printf ("memory usage: (%s)\n", "3-level sparse arrays");

#endif

  printf ("arrays: %d = %ld bytes\n", narrays,

          (long) narrays * sizeof (struct sarray));

  total += narrays * sizeof (struct sarray);

  printf ("buckets: %d = %ld bytes\n", nbuckets,

          (long) nbuckets * sizeof (struct sbucket));

  total += nbuckets * sizeof (struct sbucket);

  printf ("idxtables: %d = %ld bytes\n",

          idxsize, (long) idxsize * sizeof (void *));

  total += idxsize * sizeof (void *);

  printf ("-----------------------------------\n");

  printf ("total: %d bytes\n", total);

  printf ("===================================\n");

  objc_mutex_unlock (__objc_runtime_mutex);

}

/* Returns the uninstalled dispatch table indicator.

 If a class' dispatch table points to __objc_uninstalled_dtable

 then that means it needs its dispatch table to be installed. */

inline

struct sarray *

objc_get_uninstalled_dtable ()

{

  return __objc_uninstalled_dtable;

}