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/* Routines dealing with ObjC encoding of types

   Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001,

   2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011

   Free Software Foundation, Inc.

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 "tree.h"

#ifdef OBJCPLUS

#include "cp-tree.h"

#else

#include "c-tree.h"

#include "c-lang.h"

#endif

#include "c-family/c-common.h"

#include "c-family/c-objc.h"

#include "objc-encoding.h"

#include "objc-act.h"

/* For my_build_string().  */

#include "objc-runtime-shared-support.h"

/* For BITS_PER_UNIT.  */

#include "tm.h"

/* When building Objective-C++, we are not linking against the C front-end

   and so need to replicate the C tree-construction functions in some way.  */

#ifdef OBJCPLUS

#define OBJCP_REMAP_FUNCTIONS

#include "objcp-decl.h"

#endif  /* OBJCPLUS */

/* Set up for use of obstacks.  */

#include "obstack.h"

/* This obstack is used to accumulate the encoding of a data type.  */

static struct obstack util_obstack;

/* This points to the beginning of obstack contents, so we can free

   the whole contents.  */

static char *util_firstobj;

void objc_encoding_init (void)

{

  gcc_obstack_init (&util_obstack);

  util_firstobj = (char *) obstack_finish (&util_obstack);

}

int generating_instance_variables = 0;

static void encode_type_qualifiers (tree);

static void encode_type (tree, int, int);

static void encode_field (tree field_decl, int curtype, int format);

static tree

objc_method_parm_type (tree type)

{

  type = TREE_VALUE (TREE_TYPE (type));

  if (TREE_CODE (type) == TYPE_DECL)

    type = TREE_TYPE (type);

  return type;

}

static int

objc_encoded_type_size (tree type)

{

  int sz = int_size_in_bytes (type);

  /* Make all integer and enum types at least as large

     as an int.  */

  if (sz > 0 && INTEGRAL_TYPE_P (type))

    sz = MAX (sz, int_size_in_bytes (integer_type_node));

  /* Treat arrays as pointers, since that's how they're

     passed in.  */

  else if (TREE_CODE (type) == ARRAY_TYPE)

    sz = int_size_in_bytes (ptr_type_node);

  return sz;

}

/* Encode a method prototype.  */

tree

encode_method_prototype (tree method_decl)

{

  tree parms;

  int parm_offset, i;

  char buf[40];

  tree result;

  /* ONEWAY and BYCOPY, for remote object are the only method qualifiers.  */

  encode_type_qualifiers (TREE_PURPOSE (TREE_TYPE (method_decl)));

  /* Encode return type.  */

  encode_type (objc_method_parm_type (method_decl),

               obstack_object_size (&util_obstack),

               OBJC_ENCODE_INLINE_DEFS);

  /* Stack size.  */

  /* The first two arguments (self and _cmd) are pointers; account for

     their size.  */

  i = int_size_in_bytes (ptr_type_node);

  parm_offset = 2 * i;

  for (parms = METHOD_SEL_ARGS (method_decl); parms;

       parms = DECL_CHAIN (parms))

    {

      tree type = objc_method_parm_type (parms);

      int sz = objc_encoded_type_size (type);

      /* If a type size is not known, bail out.  */

      if (sz < 0)

        {

          error_at (DECL_SOURCE_LOCATION (method_decl),

                    "type %qT does not have a known size",

                    type);

          /* Pretend that the encoding succeeded; the compilation will

             fail nevertheless.  */

          goto finish_encoding;

        }

      parm_offset += sz;

    }

  sprintf (buf, "%d@0:%d", parm_offset, i);

  obstack_grow (&util_obstack, buf, strlen (buf));

  /* Argument types.  */

  parm_offset = 2 * i;

  for (parms = METHOD_SEL_ARGS (method_decl); parms;

       parms = DECL_CHAIN (parms))

    {

      tree type = objc_method_parm_type (parms);

      /* Process argument qualifiers for user supplied arguments.  */

      encode_type_qualifiers (TREE_PURPOSE (TREE_TYPE (parms)));

      /* Type.  */

      encode_type (type, obstack_object_size (&util_obstack),

                   OBJC_ENCODE_INLINE_DEFS);

      /* Compute offset.  */

      sprintf (buf, "%d", parm_offset);

      parm_offset += objc_encoded_type_size (type);

      obstack_grow (&util_obstack, buf, strlen (buf));

    }

  finish_encoding:

  obstack_1grow (&util_obstack, '\0');

  result = get_identifier (XOBFINISH (&util_obstack, char *));

  obstack_free (&util_obstack, util_firstobj);

  return result;

}

/* This is used to implement @encode().  */

tree

objc_build_encode_expr (tree type)

{

  tree result;

  const char *string;

  encode_type (type, obstack_object_size (&util_obstack),

               OBJC_ENCODE_INLINE_DEFS);

  obstack_1grow (&util_obstack, 0);    /* null terminate string */

  string = XOBFINISH (&util_obstack, const char *);

  /* Synthesize a string that represents the encoded struct/union.  */

  result = my_build_string (strlen (string) + 1, string);

  obstack_free (&util_obstack, util_firstobj);

  return result;

}

/* "Encode" a data type into a string, which grows in util_obstack.

   The format is described in gcc/doc/objc.texi, section 'Type

   encoding'.

   Most of the encode_xxx functions have a 'type' argument, which is

   the type to encode, and an integer 'curtype' argument, which is the

   index in the encoding string of the beginning of the encoding of

   the current type, and allows you to find what characters have

   already been written for the current type (they are the ones in the

   current encoding string starting from 'curtype').

   For example, if we are encoding a method which returns 'int' and

   takes a 'char **' argument, then when we get to the point of

   encoding the 'char **' argument, the encoded string already

   contains 'i12@0:4' (assuming a pointer size of 4 bytes).  So,

   'curtype' will be set to 7 when starting to encode 'char **'.

   During the whole of the encoding of 'char **', 'curtype' will be

   fixed at 7, so the routine encoding the second pointer can find out

   that it's actually encoding a pointer to a pointer by looking

   backwards at what has already been encoded for the current type,

   and seeing there is a "^" (meaning a pointer) in there.  */

/* Encode type qualifiers encodes one of the "PQ" Objective-C

   keywords, ie 'in', 'out', 'inout', 'bycopy', 'byref', 'oneway'.

   'const', instead, is encoded directly as part of the type.  */

static void

encode_type_qualifiers (tree declspecs)

{

  tree spec;

  for (spec = declspecs; spec; spec = TREE_CHAIN (spec))

    {

      /* FIXME: Shouldn't we use token->keyword here ? */

      if (ridpointers[(int) RID_IN] == TREE_VALUE (spec))

        obstack_1grow (&util_obstack, 'n');

      else if (ridpointers[(int) RID_INOUT] == TREE_VALUE (spec))

        obstack_1grow (&util_obstack, 'N');

      else if (ridpointers[(int) RID_OUT] == TREE_VALUE (spec))

        obstack_1grow (&util_obstack, 'o');

      else if (ridpointers[(int) RID_BYCOPY] == TREE_VALUE (spec))

        obstack_1grow (&util_obstack, 'O');

      else if (ridpointers[(int) RID_BYREF] == TREE_VALUE (spec))

        obstack_1grow (&util_obstack, 'R');

      else if (ridpointers[(int) RID_ONEWAY] == TREE_VALUE (spec))

        obstack_1grow (&util_obstack, 'V');

      else

        gcc_unreachable ();

    }

}

/* Determine if a pointee is marked read-only.  Only used by the NeXT

   runtime to be compatible with gcc-3.3.  */

static bool

pointee_is_readonly (tree pointee)

{

  while (POINTER_TYPE_P (pointee))

    pointee = TREE_TYPE (pointee);

  return TYPE_READONLY (pointee);

}

/* Encode a pointer type.  */

static void

encode_pointer (tree type, int curtype, int format)

{

  tree pointer_to = TREE_TYPE (type);

  if (flag_next_runtime)

    {

      /* This code is used to be compatible with gcc-3.3.  */

      /* For historical/compatibility reasons, the read-only qualifier

         of the pointee gets emitted _before_ the '^'.  The read-only

         qualifier of the pointer itself gets ignored, _unless_ we are

         looking at a typedef!  Also, do not emit the 'r' for anything

         but the outermost type!  */

      if (!generating_instance_variables

          && (obstack_object_size (&util_obstack) - curtype <= 1)

          && (TYPE_NAME (type) && TREE_CODE (TYPE_NAME (type)) == TYPE_DECL

              ? TYPE_READONLY (type)

              : pointee_is_readonly (pointer_to)))

        obstack_1grow (&util_obstack, 'r');

    }

  if (TREE_CODE (pointer_to) == RECORD_TYPE)

    {

      if (OBJC_TYPE_NAME (pointer_to)

          && TREE_CODE (OBJC_TYPE_NAME (pointer_to)) == IDENTIFIER_NODE)

        {

          const char *name = IDENTIFIER_POINTER (OBJC_TYPE_NAME (pointer_to));

          if (strcmp (name, TAG_OBJECT) == 0) /* '@' */

            {

              obstack_1grow (&util_obstack, '@');

              return;

            }

          else if (TYPE_HAS_OBJC_INFO (pointer_to)

                   && TYPE_OBJC_INTERFACE (pointer_to))

            {

              if (generating_instance_variables)

                {

                  obstack_1grow (&util_obstack, '@');

                  obstack_1grow (&util_obstack, '"');

                  obstack_grow (&util_obstack, name, strlen (name));

                  obstack_1grow (&util_obstack, '"');

                  return;

                }

              else

                {

                  obstack_1grow (&util_obstack, '@');

                  return;

                }

            }

          else if (strcmp (name, TAG_CLASS) == 0) /* '#' */

            {

              obstack_1grow (&util_obstack, '#');

              return;

            }

          else if (strcmp (name, TAG_SELECTOR) == 0) /* ':' */

            {

              obstack_1grow (&util_obstack, ':');

              return;

            }

        }

    }

  else if (TREE_CODE (pointer_to) == INTEGER_TYPE

           && TYPE_MODE (pointer_to) == QImode)

    {

      tree pname = TREE_CODE (OBJC_TYPE_NAME (pointer_to)) == IDENTIFIER_NODE

                  ? OBJC_TYPE_NAME (pointer_to)

                  : DECL_NAME (OBJC_TYPE_NAME (pointer_to));

      /* (BOOL *) are an exception and are encoded as ^c, while all

         other pointers to char are encoded as *.   */

      if (strcmp (IDENTIFIER_POINTER (pname), "BOOL"))

        {

          if (!flag_next_runtime)

            {

              /* The NeXT runtime adds the 'r' before getting here.  */

              /* It appears that "r*" means "const char *" rather than

                 "char *const".  "char *const" is encoded as "*",

                 which is identical to "char *", so the "const" is

                 unfortunately lost.  */

              if (TYPE_READONLY (pointer_to))

                obstack_1grow (&util_obstack, 'r');

            }

          obstack_1grow (&util_obstack, '*');

          return;

        }

    }

  /* We have a normal pointer type that does not get special treatment.  */

  obstack_1grow (&util_obstack, '^');

  encode_type (pointer_to, curtype, format);

}

static void

encode_array (tree type, int curtype, int format)

{

  tree an_int_cst = TYPE_SIZE (type);

  tree array_of = TREE_TYPE (type);

  char buffer[40];

  if (an_int_cst == NULL)

    {

      /* We are trying to encode an incomplete array.  An incomplete

         array is forbidden as part of an instance variable; but it

         may occur if the instance variable is a pointer to such an

         array.  */

      /* So the only case in which an incomplete array could occur

         (without being pointed to) is if we are encoding the

         arguments or return value of a method.  In that case, an

         incomplete array argument or return value (eg,

         -(void)display: (char[])string) is treated like a pointer

         because that is how the compiler does the function call.  A

         special, more complicated case, is when the incomplete array

         is the last member of a struct (eg, if we are encoding

         "struct { unsigned long int a;double b[];}"), which is again

         part of a method argument/return value.  In that case, we

         really need to communicate to the runtime that there is an

         incomplete array (not a pointer!) there.  So, we detect that

         special case and encode it as a zero-length array.

         Try to detect that we are part of a struct.  We do this by

         searching for '=' in the type encoding for the current type.

         NB: This hack assumes that you can't use '=' as part of a C

         identifier.

      */

      {

        char *enc = obstack_base (&util_obstack) + curtype;

        if (memchr (enc, '=',

                    obstack_object_size (&util_obstack) - curtype) == NULL)

          {

            /* We are not inside a struct.  Encode the array as a

               pointer.  */

            encode_pointer (type, curtype, format);

            return;

          }

      }

      /* Else, we are in a struct, and we encode it as a zero-length

         array.  */

      sprintf (buffer, "[" HOST_WIDE_INT_PRINT_DEC, (HOST_WIDE_INT)0);

    }

  else if (TREE_INT_CST_LOW (TYPE_SIZE (array_of)) == 0)

   sprintf (buffer, "[" HOST_WIDE_INT_PRINT_DEC, (HOST_WIDE_INT)0);

  else

    sprintf (buffer, "[" HOST_WIDE_INT_PRINT_DEC,

             TREE_INT_CST_LOW (an_int_cst)

              / TREE_INT_CST_LOW (TYPE_SIZE (array_of)));

  obstack_grow (&util_obstack, buffer, strlen (buffer));

  encode_type (array_of, curtype, format);

  obstack_1grow (&util_obstack, ']');

  return;

}

/* Encode a vector.  The vector type is a GCC extension to C.  */

static void

encode_vector (tree type, int curtype, int format)

{

  tree vector_of = TREE_TYPE (type);

  char buffer[40];

  /* Vectors are like simple fixed-size arrays.  */

  /* Output ![xx,yy,<code>] where xx is the vector_size, yy is the

     alignment of the vector, and <code> is the base type.  Eg, int

     __attribute__ ((vector_size (16))) gets encoded as ![16,32,i]

     assuming that the alignment is 32 bytes.  We include size and

     alignment in bytes so that the runtime does not have to have any

     knowledge of the actual types.

  */

  sprintf (buffer, "![" HOST_WIDE_INT_PRINT_DEC ",%d",

           /* We want to compute the equivalent of sizeof (<vector>).

              Code inspired by c_sizeof_or_alignof_type.  */

           ((TREE_INT_CST_LOW (TYPE_SIZE_UNIT (type))

             / (TYPE_PRECISION (char_type_node) / BITS_PER_UNIT))),

           /* We want to compute the equivalent of __alignof__

              (<vector>).  Code inspired by

              c_sizeof_or_alignof_type.  */

           TYPE_ALIGN_UNIT (type));

  obstack_grow (&util_obstack, buffer, strlen (buffer));

  encode_type (vector_of, curtype, format);

  obstack_1grow (&util_obstack, ']');

  return;

}

static void

encode_aggregate_fields (tree type, bool pointed_to, int curtype, int format)

{

  tree field = TYPE_FIELDS (type);

  for (; field; field = DECL_CHAIN (field))

    {

#ifdef OBJCPLUS

      /* C++ static members, and things that are not field at all,

         should not appear in the encoding.  */

      if (TREE_CODE (field) != FIELD_DECL || TREE_STATIC (field))

        continue;

#endif

      /* Recursively encode fields of embedded base classes.  */

      if (DECL_ARTIFICIAL (field) && !DECL_NAME (field)

          && TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE)

        {

          encode_aggregate_fields (TREE_TYPE (field),

                                   pointed_to, curtype, format);

          continue;

        }

      if (generating_instance_variables && !pointed_to)

        {

          tree fname = DECL_NAME (field);

          obstack_1grow (&util_obstack, '"');

          if (fname && TREE_CODE (fname) == IDENTIFIER_NODE)

            obstack_grow (&util_obstack,

                          IDENTIFIER_POINTER (fname),

                          strlen (IDENTIFIER_POINTER (fname)));

          obstack_1grow (&util_obstack, '"');

        }

      encode_field (field, curtype, format);

    }

}

static void

encode_aggregate_within (tree type, int curtype, int format, int left,

                         int right)

{

  tree name;

  /* NB: aggregates that are pointed to have slightly different encoding

     rules in that you never encode the names of instance variables.  */

  int ob_size = obstack_object_size (&util_obstack);

  bool inline_contents = false;

  bool pointed_to = false;

  if (flag_next_runtime)

    {

      if (ob_size > 0  &&  *(obstack_next_free (&util_obstack) - 1) == '^')

        pointed_to = true;

      if ((format == OBJC_ENCODE_INLINE_DEFS || generating_instance_variables)

          && (!pointed_to || ob_size - curtype == 1

              || (ob_size - curtype == 2

                  && *(obstack_next_free (&util_obstack) - 2) == 'r')))

        inline_contents = true;

    }

  else

    {

      /* c0 and c1 are the last two characters in the encoding of the

         current type; if the last two characters were '^' or '^r',

         then we are encoding an aggregate that is "pointed to".  The

         comment above applies: in that case we should avoid encoding

         the names of instance variables.

      */

      char c1 = ob_size > 1 ? *(obstack_next_free (&util_obstack) - 2) : 0;

      char c0 = ob_size > 0 ? *(obstack_next_free (&util_obstack) - 1) : 0;

      if (c0 == '^' || (c1 == '^' && c0 == 'r'))

        pointed_to = true;

      if (format == OBJC_ENCODE_INLINE_DEFS || generating_instance_variables)

        {

          if (!pointed_to)

            inline_contents = true;

          else

            {

              /* Note that the check (ob_size - curtype < 2) prevents

                 infinite recursion when encoding a structure which is

                 a linked list (eg, struct node { struct node *next;

                 }).  Each time we follow a pointer, we add one

                 character to ob_size, and curtype is fixed, so after

                 at most two pointers we stop inlining contents and

                 break the loop.

                 The other case where we don't inline is "^r", which

                 is a pointer to a constant struct.

              */

              if ((ob_size - curtype <= 2) && !(c0 == 'r'))

                inline_contents = true;

            }

        }

    }

  /* Traverse struct aliases; it is important to get the

     original struct and its tag name (if any).  */

  type = TYPE_MAIN_VARIANT (type);

  name = OBJC_TYPE_NAME (type);

  /* Open parenth/bracket.  */

  obstack_1grow (&util_obstack, left);

  /* Encode the struct/union tag name, or '?' if a tag was

     not provided.  Typedef aliases do not qualify.  */

#ifdef OBJCPLUS

  /* For compatibility with the NeXT runtime, ObjC++ encodes template

     args as a composite struct tag name. */

  if (name && TREE_CODE (name) == IDENTIFIER_NODE

      /* Did this struct have a tag?  */

      && !TYPE_WAS_ANONYMOUS (type))

    obstack_grow (&util_obstack,

                  decl_as_string (type, TFF_DECL_SPECIFIERS | TFF_UNQUALIFIED_NAME),

                  strlen (decl_as_string (type, TFF_DECL_SPECIFIERS | TFF_UNQUALIFIED_NAME)));

#else

  if (name && TREE_CODE (name) == IDENTIFIER_NODE)

    obstack_grow (&util_obstack,

                  IDENTIFIER_POINTER (name),

                  strlen (IDENTIFIER_POINTER (name)));

#endif

  else

    obstack_1grow (&util_obstack, '?');

  /* Encode the types (and possibly names) of the inner fields,

     if required.  */

  if (inline_contents)

    {

      obstack_1grow (&util_obstack, '=');

      encode_aggregate_fields (type, pointed_to, curtype, format);

    }

  /* Close parenth/bracket.  */

  obstack_1grow (&util_obstack, right);

}

/* Encode a bitfield NeXT-style (i.e., without a bit offset or the underlying

   field type.  */

static void

encode_next_bitfield (int width)

{

  char buffer[40];

  sprintf (buffer, "b%d", width);

  obstack_grow (&util_obstack, buffer, strlen (buffer));

}

/* Encodes 'type', ignoring type qualifiers (which you should encode

   beforehand if needed) with the exception of 'const', which is

   encoded by encode_type.  See above for the explanation of

   'curtype'.  'format' can be OBJC_ENCODE_INLINE_DEFS or

   OBJC_ENCODE_DONT_INLINE_DEFS.  */

static void

encode_type (tree type, int curtype, int format)

{

  enum tree_code code = TREE_CODE (type);

  /* Ignore type qualifiers other than 'const' when encoding a

     type.  */

  if (type == error_mark_node)

    return;

  if (!flag_next_runtime)

    {

      if (TYPE_READONLY (type))

        obstack_1grow (&util_obstack, 'r');

    }

  switch (code)

    {

    case ENUMERAL_TYPE:

      if (flag_next_runtime)

        {

          /* Kludge for backwards-compatibility with gcc-3.3: enums

             are always encoded as 'i' no matter what type they

             actually are (!).  */

          obstack_1grow (&util_obstack, 'i');

          break;

        }

      /* Else, they are encoded exactly like the integer type that is

         used by the compiler to store them.  */

    case INTEGER_TYPE:

      {

        char c;

        switch (GET_MODE_BITSIZE (TYPE_MODE (type)))

          {

          case 8:  c = TYPE_UNSIGNED (type) ? 'C' : 'c'; break;

          case 16: c = TYPE_UNSIGNED (type) ? 'S' : 's'; break;

          case 32:

            {

              tree int_type = type;

              if (flag_next_runtime)

                {

                  /* Another legacy kludge for compatiblity with

                     gcc-3.3: 32-bit longs are encoded as 'l' or 'L',

                     but not always.  For typedefs, we need to use 'i'

                     or 'I' instead if encoding a struct field, or a

                     pointer!  */

                  int_type =  ((!generating_instance_variables

                                && (obstack_object_size (&util_obstack)

                                    == (unsigned) curtype))

                               ? TYPE_MAIN_VARIANT (type)

                               : type);

                }

              if (int_type == long_unsigned_type_node

                  || int_type == long_integer_type_node)

                c = TYPE_UNSIGNED (type) ? 'L' : 'l';

              else

                c = TYPE_UNSIGNED (type) ? 'I' : 'i';

            }

            break;

          case 64:  c = TYPE_UNSIGNED (type) ? 'Q' : 'q'; break;

          case 128: c = TYPE_UNSIGNED (type) ? 'T' : 't'; break;

          default: gcc_unreachable ();

          }

        obstack_1grow (&util_obstack, c);

        break;

      }

    case REAL_TYPE:

      {

        char c;

        /* Floating point types.  */

        switch (GET_MODE_BITSIZE (TYPE_MODE (type)))

          {

          case 32:  c = 'f'; break;

          case 64:  c = 'd'; break;

          case 96:

          case 128: c = 'D'; break;

          default: gcc_unreachable ();

          }

        obstack_1grow (&util_obstack, c);

        break;

      }

    case VOID_TYPE:

      obstack_1grow (&util_obstack, 'v');

      break;

    case BOOLEAN_TYPE:

      obstack_1grow (&util_obstack, 'B');

      break;

    case ARRAY_TYPE:

      encode_array (type, curtype, format);

      break;

    case POINTER_TYPE:

#ifdef OBJCPLUS

    case REFERENCE_TYPE:

#endif

      encode_pointer (type, curtype, format);

      break;