expr.c

gcc-2.95.3 Linux下最常用的C编译器

/* Process expressions for the GNU compiler for the Java(TM) language.
   Copyright (C) 1996, 1997, 1998, 1999 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.  */

/* Hacked by Per Bothner <[e-mail]> February 1996. */

#include "config.h"
#include "system.h"
#include "tree.h"
#include "real.h"
#include "rtl.h"
#include "flags.h"
#include "expr.h"
#include "java-tree.h"
#include "javaop.h"
#include "java-opcodes.h"
#include "jcf.h"
#include "java-except.h"
#include "parse.h"
#include "toplev.h"
#include "except.h"

static void flush_quick_stack PROTO ((void));
static void push_value PROTO ((tree));
static tree pop_value PROTO ((tree));
static void java_stack_swap PROTO ((void));
static void java_stack_dup PROTO ((int, int));
static tree build_java_athrow PROTO ((tree));
static void build_java_jsr PROTO ((tree, tree));
static void build_java_ret PROTO ((tree));
static void expand_java_multianewarray PROTO ((tree, int));
static void expand_java_arraystore PROTO ((tree));
static void expand_java_arrayload PROTO ((tree));
static void expand_java_array_length PROTO ((void));
static tree build_java_monitor PROTO ((tree, tree));
static void expand_java_pushc PROTO ((int, tree));
static void expand_java_return PROTO ((tree));
static void expand_java_NEW PROTO ((tree));
static void expand_java_INSTANCEOF PROTO ((tree));
static void expand_java_CHECKCAST PROTO ((tree));
static void expand_iinc PROTO ((unsigned int, int, int));
static void expand_java_binop PROTO ((tree, enum tree_code));
static void note_label PROTO ((int, int));
static void expand_compare PROTO ((enum tree_code, tree, tree, int));
static void expand_test PROTO ((enum tree_code, tree, int));
static void expand_cond PROTO ((enum tree_code, tree, int));
static void expand_java_goto PROTO ((int));
#if 0
static void expand_java_call PROTO ((int, int));
static void expand_java_ret PROTO ((tree)); 
#endif
static tree pop_arguments PROTO ((tree)); 
static void expand_invoke PROTO ((int, int, int)); 
static void expand_java_field_op PROTO ((int, int, int)); 
static void java_push_constant_from_pool PROTO ((struct JCF *, int)); 
 
static tree operand_type[59];
extern struct obstack permanent_obstack;

void
init_expr_processing()
{
  operand_type[21] = operand_type[54] = int_type_node;
  operand_type[22] = operand_type[55] = long_type_node;
  operand_type[23] = operand_type[56] = float_type_node;
  operand_type[24] = operand_type[57] = double_type_node;
  operand_type[25] = operand_type[58] = ptr_type_node;
}

/* We store the stack state in two places:
   Within a basic block, we use the quick_stack, which is a
   pushdown list (TREE_LISTs) of expression nodes.
   This is the top part of the stack;  below that we use find_stack_slot.
   At the end of a basic block, the quick_stack must be flushed
   to the stack slot array (as handled by find_stack_slot).
   Using quick_stack generates better code (especially when
   compiled without optimization), because we do not have to
   explicitly store and load trees to temporary variables.

   If a variable is on the quick stack, it means the value of variable
   when the quick stack was last flushed.  Conceptually, flush_quick_stack
   saves all the the quick_stack elements in parellel.  However, that is
   complicated, so it actually saves them (i.e. copies each stack value
   to is home virtual register) from low indexes.  This allows a quick_stack
   element at index i (counting from the bottom of stack the) to references
   slot virtuals for register that are >= i, but not those that are deeper.
   This convention makes most operations easier.  For example iadd works
   even when the stack contains (reg[0], reg[1]):  It results in the
   stack containing (reg[0]+reg[1]), which is OK.  However, some stack
   operations are more complicated.  For example dup given a stack
   containing (reg[0]) would yield (reg[0], reg[0]), which would violate
   the convention, since stack value 1 would refer to a register with
   lower index (reg[0]), which flush_quick_stack does not safely handle.
   So dup cannot just add an extra element to the quick_stack, but iadd can.
*/

tree quick_stack = NULL_TREE;

/* A free-list of unused permamnet TREE_LIST nodes. */
tree tree_list_free_list = NULL_TREE;

/* The stack pointer of the Java virtual machine.
   This does include the size of the quick_stack. */

int stack_pointer;

unsigned char *linenumber_table;
int linenumber_count;

tree
truthvalue_conversion (expr)
     tree expr;
{
  /* It is simpler and generates better code to have only TRUTH_*_EXPR
     or comparison expressions as truth values at this level.

     This function should normally be identity for Java.  */

  switch (TREE_CODE (expr))
    {
    case EQ_EXPR:
    case NE_EXPR: case LE_EXPR: case GE_EXPR: case LT_EXPR: case GT_EXPR:
    case TRUTH_ANDIF_EXPR:
    case TRUTH_ORIF_EXPR:
    case TRUTH_AND_EXPR:
    case TRUTH_OR_EXPR:
    case ERROR_MARK:
      return expr;

    case INTEGER_CST:
      return integer_zerop (expr) ? boolean_false_node : boolean_true_node;

    case REAL_CST:
      return real_zerop (expr) ? boolean_false_node : boolean_true_node;

    /* are these legal? XXX JH */
    case NEGATE_EXPR:
    case ABS_EXPR:
    case FLOAT_EXPR:
    case FFS_EXPR:
      /* These don't change whether an object is non-zero or zero.  */
      return truthvalue_conversion (TREE_OPERAND (expr, 0));

    case COND_EXPR:
      /* Distribute the conversion into the arms of a COND_EXPR.  */
      return fold (build (COND_EXPR, boolean_type_node, TREE_OPERAND (expr, 0),
                          truthvalue_conversion (TREE_OPERAND (expr, 1)),
                          truthvalue_conversion (TREE_OPERAND (expr, 2))));

    case NOP_EXPR:
      /* If this is widening the argument, we can ignore it.  */
      if (TYPE_PRECISION (TREE_TYPE (expr))
          >= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (expr, 0))))
        return truthvalue_conversion (TREE_OPERAND (expr, 0));
      /* fall through to default */

    default:
      return fold (build (NE_EXPR, boolean_type_node, expr, boolean_false_node));
    }
}

#ifdef JAVA_USE_HANDLES
/* Given a pointer to a handle, get a pointer to an object. */

tree
unhand_expr (expr)
     tree expr;
{
  tree field, handle_type;
  expr = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (expr)), expr);
  handle_type = TREE_TYPE (expr);
  field = TYPE_FIELDS (handle_type);
  expr = build (COMPONENT_REF, TREE_TYPE (field), expr, field);
  return expr;
}
#endif

/* Save any stack slots that happen to be in the quick_stack into their
   home virtual register slots.

   The copy order is from low stack index to high, to support the invariant
   that the expression for a slot may contain decls for stack slots with
   higher (or the same) index, but not lower. */

static void
flush_quick_stack ()
{
  int stack_index = stack_pointer;
  register tree prev, cur, next;

  /* First reverse the quick_stack, and count the number of slots it has. */
  for (cur = quick_stack, prev = NULL_TREE; cur != NULL_TREE; cur = next)
    {
      next = TREE_CHAIN (cur);
      TREE_CHAIN (cur) = prev;
      prev = cur;
      stack_index -= 1 + TYPE_IS_WIDE (TREE_TYPE (TREE_VALUE (cur)));
    }
  quick_stack = prev;

  while (quick_stack != NULL_TREE)
    {
      tree decl;
      tree node = quick_stack, type;
      quick_stack = TREE_CHAIN (node);
      TREE_CHAIN (node) = tree_list_free_list;
      tree_list_free_list = node;
      node = TREE_VALUE (node);
      type = TREE_TYPE (node);

      decl = find_stack_slot (stack_index, type);
      if (decl != node)
	  expand_assignment (decl, node, 0, 0);
      stack_index += 1 + TYPE_IS_WIDE (type);
    }
}

void
push_type (type)
     tree type;
{
  int n_words;
  type = promote_type (type);
  n_words = 1 + TYPE_IS_WIDE (type);
  if (stack_pointer + n_words > DECL_MAX_STACK (current_function_decl))
    fatal ("stack overflow");
  stack_type_map[stack_pointer++] = type;
  n_words--;
  while (--n_words >= 0)
    stack_type_map[stack_pointer++] = TYPE_SECOND;
}

static void
push_value (value)
     tree value;
{
  tree type = TREE_TYPE (value);
  if (TYPE_PRECISION (type) < 32 && INTEGRAL_TYPE_P (type))
    {
      type = promote_type (type);
      value = convert (type, value);
    }
  push_type (type);
  if (tree_list_free_list == NULL_TREE)
    quick_stack = perm_tree_cons (NULL_TREE, value, quick_stack);
  else
    {
      tree node = tree_list_free_list;
      tree_list_free_list = TREE_CHAIN (tree_list_free_list);
      TREE_VALUE (node) = value;
      TREE_CHAIN (node) = quick_stack;
      quick_stack = node;
    }
}

/* Pop a type from the type stack.
   TYPE is the expected type.   Return the actual type, which must be
   convertible to TYPE, otherwise NULL_TREE is returned. */

tree
pop_type_0 (type)
     tree type;
{
  int n_words;
  tree t;
  if (TREE_CODE (type) == RECORD_TYPE)
    type = promote_type (type);
  n_words = 1 + TYPE_IS_WIDE (type);
  if (stack_pointer < n_words)
    fatal ("stack underflow");
  while (--n_words > 0)
    {
      if (stack_type_map[--stack_pointer] != void_type_node)
	fatal ("Invalid multi-word value on type stack");
    }
  t = stack_type_map[--stack_pointer];
  if (type == NULL_TREE || t == type)
    return t;
  if (INTEGRAL_TYPE_P (type) && INTEGRAL_TYPE_P (t)
      && TYPE_PRECISION (type) <= 32 && TYPE_PRECISION (t) <= 32)
      return t;
  if (TREE_CODE (type) == POINTER_TYPE && TREE_CODE (t) == POINTER_TYPE)
    {
      if (type == ptr_type_node || type == object_ptr_type_node)
	return t;
      else if (t == ptr_type_node)  /* Special case for null reference. */
	return type;
      else if (can_widen_reference_to (t, type))
	return t;
      /* This is a kludge, but matches what Sun's verifier does.
	 It can be tricked, but is safe as long as type errors
	 (i.e. interface method calls) are caught at run-time. */
      else if (CLASS_INTERFACE (TYPE_NAME (TREE_TYPE (type)))
	       && t == object_ptr_type_node)
	return t;
    }
  return NULL_TREE;
}

/* Pop a type from the type stack.
   TYPE is the expected type.  Return the actual type, which must be
   convertible to TYPE, otherwise call error. */

tree
pop_type (type)
     tree type;
{
  tree t = pop_type_0 (type);
  if (t != NULL_TREE)
    return t;
  error ("unexpected type on stack");
  return type;
}

/* Return 1f if SOURCE_TYPE can be safely widened to TARGET_TYPE.
   Handles array types and interfaces.  */

int
can_widen_reference_to (source_type, target_type)
     tree source_type, target_type;
{
  if (source_type == ptr_type_node || target_type == object_ptr_type_node)
    return 1;

  /* Get rid of pointers  */
  if (TREE_CODE (source_type) == POINTER_TYPE)
    source_type = TREE_TYPE (source_type);
  if (TREE_CODE (target_type) == POINTER_TYPE)
    target_type = TREE_TYPE (target_type);

  if (source_type == target_type)
    return 1;
  else
    {
      source_type = HANDLE_TO_CLASS_TYPE (source_type);
      target_type = HANDLE_TO_CLASS_TYPE (target_type);
      if (TYPE_ARRAY_P (source_type) || TYPE_ARRAY_P (target_type))
	{
	  HOST_WIDE_INT source_length, target_length;
	  if (TYPE_ARRAY_P (source_type) != TYPE_ARRAY_P (target_type))
	    return 0;
	  target_length = java_array_type_length (target_type);
	  if (target_length >= 0)
	    {
	      source_length = java_array_type_length (source_type);
	      if (source_length != target_length)
		return 0;
	    }
	  source_type = TYPE_ARRAY_ELEMENT (source_type);
	  target_type = TYPE_ARRAY_ELEMENT (target_type);
	  if (source_type == target_type)
	    return 1;
	  if (TREE_CODE (source_type) != POINTER_TYPE
	      || TREE_CODE (target_type) != POINTER_TYPE)
	    return 0;
	  return can_widen_reference_to (source_type, target_type);
	}
      else
	{
	  int source_depth = class_depth (source_type);
	  int target_depth = class_depth (target_type);

	  if (CLASS_INTERFACE (TYPE_NAME (target_type)))
	    {
	      /* target_type is OK if source_type or source_type ancestors
		 implement target_type. We handle multiple sub-interfaces  */

	      tree basetype_vec = TYPE_BINFO_BASETYPES (source_type);
	      int n = TREE_VEC_LENGTH (basetype_vec), i;
	      for (i=0 ; i < n; i++)
	        if (can_widen_reference_to 
		    (TREE_TYPE (TREE_VEC_ELT (basetype_vec, i)),
		     target_type))
		  return 1;
		if (n == 0)
		  return 0;
	    }

	  for ( ; source_depth > target_depth;  source_depth--) 
	    {
	      source_type = TYPE_BINFO_BASETYPE (source_type, 0); 
	    }
	  return source_type == target_type;
	}
    }
}

static tree
pop_value (type)
     tree type;
{
  type = pop_type (type);
  if (quick_stack)
    {
      tree node = quick_stack;
      quick_stack = TREE_CHAIN (quick_stack);
      TREE_CHAIN (node) = tree_list_free_list;
      tree_list_free_list = node;
      node = TREE_VALUE (node);
      return node;
    }
  else
    return find_stack_slot (stack_pointer, promote_type (type));
}


/* Pop and discrad the top COUNT stack slots. */

static void
java_stack_pop (count)
     int count;
{
  while (count > 0)
    {
      tree type, val;
      if (stack_pointer == 0)
	fatal ("stack underflow");
      type = stack_type_map[stack_pointer - 1];
      if (type == TYPE_SECOND)