constants.c

gcc-2.95.3 Linux下最常用的C编译器

/* Handle the constant pool of the Java(TM) Virtual Machine.
   Copyright (C) 1997 Free Software Foundation, Inc.

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, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. 

Java and all Java-based marks are trademarks or registered trademarks
of Sun Microsystems, Inc. in the United States and other countries.
The Free Software Foundation is independent of Sun Microsystems, Inc.  */

#include "config.h"
#include "system.h"
#include "jcf.h"
#include "tree.h"
#include "java-tree.h"
#include "toplev.h"

extern struct obstack permanent_obstack;

static void set_constant_entry PROTO ((CPool *, int, int, jword));
static int find_class_or_string_constant PROTO ((CPool *, int, tree));
static int find_name_and_type_constant PROTO ((CPool *, tree, tree));
static tree get_tag_node PROTO ((int));
static tree build_constant_data_ref PROTO ((void));

/* Set the INDEX'th constant in CPOOL to have the given TAG and VALUE. */

static void
set_constant_entry (cpool, index, tag, value)
     CPool *cpool;
     int index;
     int tag;
     jword value;
{
  if (cpool->data == NULL)
    {
      cpool->capacity = 100;
      cpool->tags = (uint8*) xmalloc (sizeof(uint8) * cpool->capacity);
      cpool->data = (jword*) xmalloc (sizeof(jword) * cpool->capacity);
      cpool->count = 1;
    }
  if (index >= cpool->capacity)
    {
      cpool->capacity *= 2;
      if (index >= cpool->capacity)
	cpool->capacity = index + 10;
      cpool->tags = (uint8*) xrealloc (cpool->tags,
				       sizeof(uint8) * cpool->capacity);
      cpool->data = (jword*) xrealloc (cpool->data,
				       sizeof(jword) * cpool->capacity);
    }
  if (index >= cpool->count)
    cpool->count = index + 1;
  cpool->tags[index] = tag;
  cpool->data[index] = value;
}

/* Find (or create) a constant pool entry matching TAG and VALUE. */

int
find_constant1 (cpool, tag, value)
     CPool *cpool;
     int tag;
     jword value;
{
  int i;
  for (i = cpool->count;  --i > 0; )
    {
      if (cpool->tags[i] == tag && cpool->data[i] == value)
	return i;
    }
  i = cpool->count == 0 ? 1 : cpool->count;
  set_constant_entry (cpool, i, tag, value);
  return i;
}

/* Find a double-word constant pool entry matching TAG and WORD1/WORD2. */

int
find_constant2 (cpool, tag, word1, word2)
     CPool *cpool;
     int tag;
     jword word1, word2;
{
  int i;
  for (i = cpool->count - 1;  --i > 0; )
    {
      if (cpool->tags[i] == tag
	  && cpool->data[i] == word1
	  && cpool->data[i+1] == word2)
	return i;
    }
  i = cpool->count == 0 ? 1 : cpool->count;
  set_constant_entry (cpool, i, tag, word1);
  set_constant_entry (cpool, i+1, 0, word2);
  return i;
}

int
find_utf8_constant (cpool, name)
     CPool *cpool;
     tree name;
{
  if (name == NULL_TREE)
    return 0;
  return find_constant1 (cpool, CONSTANT_Utf8, (jword) name);
}

static int
find_class_or_string_constant (cpool, tag, name)
     CPool *cpool;
     int tag;
     tree name;
{
  int j = find_utf8_constant (cpool, name);
  int i;
  for (i = cpool->count;  --i > 0; )
    {
      if (cpool->tags[i] == tag && cpool->data[i] == (jword) j)
	return i;
    }
  i = cpool->count;
  set_constant_entry (cpool, i, tag, (jword) j);
  return i;
}

int
find_class_constant (cpool, type)
     CPool *cpool;
     tree type;
{
  return find_class_or_string_constant (cpool, CONSTANT_Class,
					build_internal_class_name (type));
}

/* Allocate a CONSTANT_string entry given a STRING_CST. */

int
find_string_constant (cpool, string)
     CPool *cpool;
     tree string;
{
  string = get_identifier (TREE_STRING_POINTER (string));
  return find_class_or_string_constant (cpool, CONSTANT_String, string);

}

/* Find (or create) a CONSTANT_NameAndType matching NAME and TYPE.
   Return its index in the constant pool CPOOL. */

static int
find_name_and_type_constant (cpool, name, type)
     CPool *cpool;
     tree name;
     tree type;
{
  int name_index = find_utf8_constant (cpool, name);
  int type_index = find_utf8_constant (cpool, build_java_signature (type));
  return find_constant1 (cpool, CONSTANT_NameAndType,
			 (name_index << 16) | type_index);
}

/* Find (or create) a CONSTANT_Fieldref for DECL (a FIELD_DECL or VAR_DECL).
   Return its index in the constant pool CPOOL. */

int
find_fieldref_index (cpool, decl)
     CPool *cpool;
     tree decl;
{
  int class_index = find_class_constant (cpool, DECL_CONTEXT (decl));
  int name_type_index
    = find_name_and_type_constant (cpool, DECL_NAME (decl), TREE_TYPE (decl));
  return find_constant1 (cpool, CONSTANT_Fieldref,
			 (class_index << 16) | name_type_index);
}

/* Find (or create) a CONSTANT_Methodref for DECL (a FUNCTION_DECL).
   Return its index in the constant pool CPOOL. */

int
find_methodref_index (cpool, decl)
     CPool *cpool;
     tree decl;
{
  tree mclass = DECL_CONTEXT (decl);
  int class_index = find_class_constant (cpool, mclass);
  tree name = DECL_CONSTRUCTOR_P (decl) ? init_identifier_node
    : DECL_NAME (decl);
  int name_type_index
    = find_name_and_type_constant (cpool, name, TREE_TYPE (decl));
  return find_constant1 (cpool,
			 CLASS_INTERFACE (TYPE_NAME (mclass))
			 ? CONSTANT_InterfaceMethodref
			 : CONSTANT_Methodref,
			 (class_index << 16) | name_type_index);
}

#define PUT1(X)  (*ptr++ = (X))
#define PUT2(X)  (PUT1((X) >> 8), PUT1(X))
#define PUT4(X)  (PUT2((X) >> 16), PUT2(X))
#define PUTN(P, N)  (bcopy(P, ptr, N), ptr += (N))

/* Give the number of bytes needed in a .class file for the CPOOL
   constant pool.  Includes the 2-byte constant_pool_count. */

int
count_constant_pool_bytes (cpool)
     CPool *cpool;
{
  int size = 2;
  int i = 1;
  for ( ;  i < cpool->count;  i++)
    {
      size++;
      switch (cpool->tags[i])
	{
	case CONSTANT_NameAndType:
	case CONSTANT_Fieldref:
	case CONSTANT_Methodref:
	case CONSTANT_InterfaceMethodref:
	case CONSTANT_Float:
	case CONSTANT_Integer:
	  size += 4;
	  break;
	case CONSTANT_Class:
	case CONSTANT_String:
	  size += 2;
	  break;
	case CONSTANT_Long:
	case CONSTANT_Double:
	  size += 8;
	  i++;
	  break;
	case CONSTANT_Utf8:
	  {
	    tree t = (tree) cpool->data[i];
	    int len = IDENTIFIER_LENGTH (t);
	    size += len + 2;
	  }
	  break;
	default:
	  /* Second word of CONSTANT_Long and  CONSTANT_Double. */
	  size--;
	}
    }
  return size;
}

/* Write the constant pool CPOOL into BUFFER.
   The length of BUFFER is LENGTH, which must match the needed length. */

void
write_constant_pool (cpool, buffer, length)
     CPool *cpool;
     unsigned char* buffer;
     int length;
{
  unsigned char* ptr = buffer;
  int i = 1;
  jword *datap = &cpool->data[1];
  PUT2 (cpool->count);
  for ( ;  i < cpool->count;  i++, datap++)
    {
      int tag = cpool->tags[i];
      PUT1 (tag);
      switch (tag)
	{
	case CONSTANT_NameAndType:
	case CONSTANT_Fieldref:
	case CONSTANT_Methodref:
	case CONSTANT_InterfaceMethodref:
	case CONSTANT_Float:
	case CONSTANT_Integer:
	  PUT4 (*datap);
	  break;
	case CONSTANT_Class:
	case CONSTANT_String:
	  PUT2 (*datap);
	  break;
	  break;
	case CONSTANT_Long:
	case CONSTANT_Double:
	  PUT4(*datap);
	  i++;
	  datap++;
	  PUT4 (*datap);
	  break;
	case CONSTANT_Utf8:
	  {
	    tree t = (tree) *datap;
	    int len = IDENTIFIER_LENGTH (t);
	    PUT2 (len);
	    PUTN (IDENTIFIER_POINTER (t), len);
	  }
	  break;
	}
    }
  if (ptr != buffer + length)
    fatal("internal error - incorrect constant pool");
}

CPool *outgoing_cpool;

/* If non-NULL, an ADDR_EXPR referencing a VAR_DECL containing
   the constant data array for the current class. */
tree current_constant_pool_data_ref;

/* A Cache for build_int_2 (CONSTANT_XXX, 0). */
static tree tag_nodes[13];

static tree
get_tag_node (tag)
     int tag;
{
  if (tag_nodes[tag] == NULL_TREE)
    {
      push_obstacks (&permanent_obstack, &permanent_obstack);
      tag_nodes[tag] = build_int_2 (tag, 0);
      pop_obstacks ();
    }
  return tag_nodes[tag];
}

/* Look for a constant pool entry that matches TAG and NAME.
   Creates a new entry if not found.
   TAG is one of CONSTANT_Utf8, CONSTANT_String or CONSTANT_Class.
   NAME is an IDENTIFIER_NODE naming the Utf8 constant, string, or class.
   Returns the index of the entry. */

int
alloc_name_constant (tag, name)
     int tag;
     tree name;
{
  return find_constant1 (outgoing_cpool, tag, (jword) name);
}

/* Build an identifier for the internal name of reference type TYPE. */

tree
build_internal_class_name (type)
     tree type;
{
  tree name;
  if (TYPE_ARRAY_P (type))
    name = build_java_signature (type);
  else
    {
      name = TYPE_NAME (type);
      if (TREE_CODE (name) != IDENTIFIER_NODE)
	name = DECL_NAME (name);
      name = identifier_subst (name, "", '.', '/', "");
    }
  return name;
}

/* Look for a CONSTANT_Class entry for CLAS, creating a new one if needed. */

int
alloc_class_constant (clas)
     tree clas;
{
  tree class_name = build_internal_class_name (clas);
  
  return alloc_name_constant (CONSTANT_Class,
			      (unmangle_classname 
			       (IDENTIFIER_POINTER(class_name),
				IDENTIFIER_LENGTH(class_name))));
}

/* Return a reference to the data array of the current constant pool. */

static tree
build_constant_data_ref ()
{
  if (current_constant_pool_data_ref == NULL_TREE)
    {
      tree decl;
      tree decl_name = mangled_classname ("_CD_", current_class);
      push_obstacks (&permanent_obstack, &permanent_obstack);
      decl = build_decl (VAR_DECL, decl_name,
			 build_array_type (ptr_type_node,
					   one_elt_array_domain_type));
      TREE_STATIC (decl) = 1;
      make_decl_rtl (decl, NULL, 1);
      pop_obstacks ();
      current_constant_pool_data_ref
	= build1 (ADDR_EXPR, ptr_type_node, decl);
    }
  return current_constant_pool_data_ref;
}

/* Get the pointer value at the INDEX'th element of the constant pool. */

tree
build_ref_from_constant_pool (index)
     int index;
{
  tree t = build_constant_data_ref ();
  index *= int_size_in_bytes (ptr_type_node);
  t = fold (build (PLUS_EXPR, ptr_type_node,
                              t, build_int_2 (index, 0)));
  return build1 (INDIRECT_REF, ptr_type_node, t);
}

/* Build an initializer for the constants field of the current constal pool.
   Should only be called at top-level, since it may emit declarations. */

tree
build_constants_constructor ()
{
  tree tags_value, data_value;
  tree cons;
  tree tags_list = NULL_TREE;
  tree data_list = NULL_TREE;
  int i;
  for (i = outgoing_cpool->count;  --i > 0; )
    {
      tags_list
	= tree_cons (NULL_TREE, get_tag_node (outgoing_cpool->tags[i]),
		     tags_list);
      data_list
	= tree_cons (NULL_TREE, build_utf8_ref ((tree)outgoing_cpool->data[i]),
		     data_list);
    }
  if (outgoing_cpool->count > 0)
    {
      tree index_type;
      tree data_decl, tags_decl, tags_type;
      tree max_index = build_int_2 (outgoing_cpool->count - 1, 0);
      TREE_TYPE (max_index) = sizetype;
      index_type = build_index_type (max_index);

      /* Add dummy 0'th element of constant pool. */
      tags_list = tree_cons (NULL_TREE, get_tag_node (0), tags_list);
      data_list = tree_cons (NULL_TREE, null_pointer_node, data_list);
  
      data_decl = TREE_OPERAND (build_constant_data_ref (), 0);
      TREE_TYPE (data_decl) = build_array_type (ptr_type_node, index_type), 
      DECL_INITIAL (data_decl) = build (CONSTRUCTOR, TREE_TYPE (data_decl),
					NULL_TREE, data_list);
      DECL_SIZE (data_decl) = TYPE_SIZE (TREE_TYPE (data_decl));
      rest_of_decl_compilation (data_decl, (char*) 0, 1, 0);
      data_value = build_address_of (data_decl);

      tags_type = build_array_type (unsigned_byte_type_node, index_type);
      tags_decl = build_decl (VAR_DECL, mangled_classname ("_CT_", 
							   current_class),
			      tags_type);
      TREE_STATIC (tags_decl) = 1;
      DECL_INITIAL (tags_decl) = build (CONSTRUCTOR, tags_type,
					NULL_TREE, tags_list);
      rest_of_decl_compilation (tags_decl, (char*) 0, 1, 0);
      tags_value = build_address_of (tags_decl);
    }
  else
    {
      data_value = null_pointer_node;
      tags_value = null_pointer_node;
    }
  START_RECORD_CONSTRUCTOR (cons, constants_type_node);
  PUSH_FIELD_VALUE (cons, "size", build_int_2 (outgoing_cpool->count, 0));
  PUSH_FIELD_VALUE (cons, "tags", tags_value);
  PUSH_FIELD_VALUE (cons, "data", data_value);
  FINISH_RECORD_CONSTRUCTOR (cons);
  return cons;
}