* eval.c (evaluate_subexp): Clear expect_type except for C++ and CHILL.

[binutils-gdb.git] / gdb / eval.c

/* Evaluate expressions for GDB.
   Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994
   Free Software Foundation, Inc.

This file is part of GDB.

This program 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 of the License, or
(at your option) any later version.

This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include <string.h>
#include "symtab.h"
#include "gdbtypes.h"
#include "value.h"
#include "expression.h"
#include "target.h"
#include "frame.h"
#include "demangle.h"
#include "language.h"   /* For CAST_IS_CONVERSION */
#include "f-lang.h" /* for array bound stuff */

/* Values of NOSIDE argument to eval_subexp.  */

enum noside
{
  EVAL_NORMAL,
  EVAL_SKIP,                    /* Only effect is to increment pos.  */
  EVAL_AVOID_SIDE_EFFECTS       /* Don't modify any variables or
                                   call any functions.  The value
                                   returned will have the correct
                                   type, and will have an
                                   approximately correct lvalue
                                   type (inaccuracy: anything that is
                                   listed as being in a register in
                                   the function in which it was
                                   declared will be lval_register).  */
};

/* Prototypes for local functions. */

static value_ptr evaluate_subexp_for_sizeof PARAMS ((struct expression *,
                                                     int *));

static value_ptr evaluate_subexp_with_coercion PARAMS ((struct expression *,
                                                        int *, enum noside));

static value_ptr evaluate_subexp_for_address PARAMS ((struct expression *,
                                                      int *, enum noside));

static value_ptr evaluate_subexp PARAMS ((struct type *, struct expression *,
                                          int *, enum noside));

\f
/* Parse the string EXP as a C expression, evaluate it,
   and return the result as a number.  */

CORE_ADDR
parse_and_eval_address (exp)
     char *exp;
{
  struct expression *expr = parse_expression (exp);
  register CORE_ADDR addr;
  register struct cleanup *old_chain = 
      make_cleanup (free_current_contents, &expr);

  addr = value_as_pointer (evaluate_expression (expr));
  do_cleanups (old_chain);
  return addr;
}

/* Like parse_and_eval_address but takes a pointer to a char * variable
   and advanced that variable across the characters parsed.  */

CORE_ADDR
parse_and_eval_address_1 (expptr)
     char **expptr;
{
  struct expression *expr = parse_exp_1 (expptr, (struct block *)0, 0);
  register CORE_ADDR addr;
  register struct cleanup *old_chain =
      make_cleanup (free_current_contents, &expr);

  addr = value_as_pointer (evaluate_expression (expr));
  do_cleanups (old_chain);
  return addr;
}

value_ptr
parse_and_eval (exp)
     char *exp;
{
  struct expression *expr = parse_expression (exp);
  register value_ptr val;
  register struct cleanup *old_chain
    = make_cleanup (free_current_contents, &expr);

  val = evaluate_expression (expr);
  do_cleanups (old_chain);
  return val;
}

/* Parse up to a comma (or to a closeparen)
   in the string EXPP as an expression, evaluate it, and return the value.
   EXPP is advanced to point to the comma.  */

value_ptr
parse_to_comma_and_eval (expp)
     char **expp;
{
  struct expression *expr = parse_exp_1 (expp, (struct block *) 0, 1);
  register value_ptr val;
  register struct cleanup *old_chain
    = make_cleanup (free_current_contents, &expr);

  val = evaluate_expression (expr);
  do_cleanups (old_chain);
  return val;
}
\f
/* Evaluate an expression in internal prefix form
   such as is constructed by parse.y.

   See expression.h for info on the format of an expression.  */

value_ptr
evaluate_expression (exp)
     struct expression *exp;
{
  int pc = 0;
  return evaluate_subexp (NULL_TYPE, exp, &pc, EVAL_NORMAL);
}

/* Evaluate an expression, avoiding all memory references
   and getting a value whose type alone is correct.  */

value_ptr
evaluate_type (exp)
     struct expression *exp;
{
  int pc = 0;
  return evaluate_subexp (NULL_TYPE, exp, &pc, EVAL_AVOID_SIDE_EFFECTS);
}

static value_ptr
evaluate_subexp (expect_type, exp, pos, noside)
     struct type *expect_type;
     register struct expression *exp;
     register int *pos;
     enum noside noside;
{
  enum exp_opcode op;
  int tem, tem2, tem3;
  register int pc, pc2 = 0, oldpos;
  register value_ptr arg1 = NULL, arg2 = NULL, arg3;
  struct type *type;
  int nargs;
  value_ptr *argvec;
  int tmp_pos, tmp1_pos; 
  struct symbol *tmp_symbol; 
  int upper, lower, retcode; 
  int code;
  struct internalvar *var; 

  /* This expect_type crap should not be used for C.  C expressions do
     not have any notion of expected types, never has and (goddess
     willing) never will.  The C++ code uses it for some twisted
     purpose (I haven't investigated but I suspect it just the usual
     combination of Stroustrup figuring out some crazy language
     feature and Tiemann figuring out some crazier way to try to
     implement it).  CHILL has the tuple stuff; I don't know enough
     about CHILL to know whether expected types is the way to do it.
     FORTRAN I don't know.  */
  if (current_language->la_language != language_cplus
      && current_language->la_language != language_chill)
    expect_type = NULL_TYPE;

  pc = (*pos)++;
  op = exp->elts[pc].opcode;

  switch (op)
    {
    case OP_SCOPE:
      tem = longest_to_int (exp->elts[pc + 2].longconst);
      (*pos) += 4 + BYTES_TO_EXP_ELEM (tem + 1);
      arg1 = value_struct_elt_for_reference (exp->elts[pc + 1].type,
                                             0,
                                             exp->elts[pc + 1].type,
                                             &exp->elts[pc + 3].string,
                                             expect_type);
      if (arg1 == NULL)
        error ("There is no field named %s", &exp->elts[pc + 3].string);
      return arg1;

    case OP_LONG:
      (*pos) += 3;
      return value_from_longest (exp->elts[pc + 1].type,
                                 exp->elts[pc + 2].longconst);

    case OP_DOUBLE:
      (*pos) += 3;
      return value_from_double (exp->elts[pc + 1].type,
                                exp->elts[pc + 2].doubleconst);

    case OP_VAR_VALUE:
      (*pos) += 3;
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        {
          struct symbol * sym = exp->elts[pc + 2].symbol;
          enum lval_type lv;

          switch (SYMBOL_CLASS (sym))
            {
            case LOC_CONST:
            case LOC_LABEL:
            case LOC_CONST_BYTES:
              lv = not_lval;
              break;

            case LOC_REGISTER:
            case LOC_REGPARM:
              lv = lval_register;
              break;

            default:
              lv = lval_memory;
              break;
            }

          return value_zero (SYMBOL_TYPE (sym), lv);
        }
      else
        return value_of_variable (exp->elts[pc + 2].symbol,
                                  exp->elts[pc + 1].block);

    case OP_LAST:
      (*pos) += 2;
      return
        access_value_history (longest_to_int (exp->elts[pc + 1].longconst));

    case OP_REGISTER:
      (*pos) += 2;
      return value_of_register (longest_to_int (exp->elts[pc + 1].longconst));

    case OP_BOOL:
      (*pos) += 2;
      if (current_language->la_language == language_fortran)
        return value_from_longest (builtin_type_f_logical_s2,
                                   exp->elts[pc + 1].longconst);
      else
        return value_from_longest (builtin_type_chill_bool,
                                   exp->elts[pc + 1].longconst);

    case OP_INTERNALVAR:
      (*pos) += 2;
      return value_of_internalvar (exp->elts[pc + 1].internalvar);

    case OP_STRING:
      tem = longest_to_int (exp->elts[pc + 1].longconst);
      (*pos) += 3 + BYTES_TO_EXP_ELEM (tem + 1);
      if (noside == EVAL_SKIP)
        goto nosideret;
      return value_string (&exp->elts[pc + 2].string, tem);

    case OP_BITSTRING:
      error ("support for OP_BITSTRING unimplemented");
      break;

    case OP_ARRAY:
      (*pos) += 3;
      tem2 = longest_to_int (exp->elts[pc + 1].longconst);
      tem3 = longest_to_int (exp->elts[pc + 2].longconst);
      nargs = tem3 - tem2 + 1;

      if (expect_type != NULL_TYPE && noside != EVAL_SKIP
          && TYPE_CODE (expect_type) == TYPE_CODE_STRUCT)
        {
          value_ptr rec = allocate_value (expect_type);
          if (TYPE_NFIELDS (expect_type) != nargs)
            error ("wrong number of initialiers for structure type");
          for (tem = 0; tem < nargs; tem++)
            {
              struct type *field_type = TYPE_FIELD_TYPE (expect_type, tem);
              value_ptr field_val = evaluate_subexp (field_type,
                                                     exp, pos, noside);
              int bitsize, bitpos;
              char *addr;
              if (VALUE_TYPE (field_val) != field_type)
                field_val = value_cast (field_type, field_val);
#if 1
              bitsize = TYPE_FIELD_BITSIZE (expect_type, tem);
              bitpos = TYPE_FIELD_BITPOS (expect_type, tem);
              addr = VALUE_CONTENTS (rec);
              addr += bitpos / 8;
              if (bitsize)
                modify_field (addr, value_as_long (field_val),
                              bitpos % 8, bitsize);
              else
                memcpy (addr, VALUE_CONTENTS (field_val),
                        TYPE_LENGTH (VALUE_TYPE (field_val)));
#else
              value_assign (value_primitive_field (rec, 0, tem, expect_type),
                            field_val);
#endif
            }
          return rec;
        }

      if (expect_type != NULL_TYPE && noside != EVAL_SKIP
          && TYPE_CODE (expect_type) == TYPE_CODE_ARRAY)
        {
          struct type *range_type = TYPE_FIELD_TYPE (expect_type, 0);
          struct type *element_type = TYPE_TARGET_TYPE (expect_type);
          LONGEST low_bound =  TYPE_FIELD_BITPOS (range_type, 0);
          LONGEST high_bound = TYPE_FIELD_BITPOS (range_type, 1);
          int element_size = TYPE_LENGTH (element_type);
          value_ptr rec = allocate_value (expect_type);
          if (nargs != (high_bound - low_bound + 1))
            error ("wrong number of initialiers for array type");
          for (tem = low_bound;  tem <= high_bound;  tem++)
            {
              value_ptr element = evaluate_subexp (element_type,
                                                   exp, pos, noside);
              memcpy (VALUE_CONTENTS_RAW (rec)
                      + (tem - low_bound) * element_size,
                      VALUE_CONTENTS (element),
                      element_size);
            }
          return rec;
        }

      argvec = (value_ptr *) alloca (sizeof (value_ptr) * nargs);
      for (tem = 0; tem < nargs; tem++)
        {
          /* Ensure that array expressions are coerced into pointer objects. */
          argvec[tem] = evaluate_subexp_with_coercion (exp, pos, noside);
        }
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (current_language->la_language == language_fortran)
         /* For F77, we need to do special things to literal strings */ 
         return (f77_value_literal_string (tem2, tem3, argvec));
      return value_array (tem2, tem3, argvec);
      break;

    case TERNOP_COND:
      /* Skip third and second args to evaluate the first one.  */
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (value_logical_not (arg1))
        {
          evaluate_subexp (NULL_TYPE, exp, pos, EVAL_SKIP);
          return evaluate_subexp (NULL_TYPE, exp, pos, noside);
        }
      else
        {
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
          evaluate_subexp (NULL_TYPE, exp, pos, EVAL_SKIP);
          return arg2;
        }

    case OP_FUNCALL:
      (*pos) += 2;
      op = exp->elts[*pos].opcode;
      if (op == STRUCTOP_MEMBER || op == STRUCTOP_MPTR)
        {
          LONGEST fnptr;

          nargs = longest_to_int (exp->elts[pc + 1].longconst) + 1;
          /* First, evaluate the structure into arg2 */
          pc2 = (*pos)++;

          if (noside == EVAL_SKIP)
            goto nosideret;

          if (op == STRUCTOP_MEMBER)
            {
              arg2 = evaluate_subexp_for_address (exp, pos, noside);
            }
          else
            {
              arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
            }

          /* If the function is a virtual function, then the
             aggregate value (providing the structure) plays
             its part by providing the vtable.  Otherwise,
             it is just along for the ride: call the function
             directly.  */

          arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);

          fnptr = value_as_long (arg1);

          if (METHOD_PTR_IS_VIRTUAL(fnptr))
            {
              int fnoffset = METHOD_PTR_TO_VOFFSET(fnptr);
              struct type *basetype;
              struct type *domain_type =
                  TYPE_DOMAIN_TYPE (TYPE_TARGET_TYPE (VALUE_TYPE (arg1)));
              int i, j;
              basetype = TYPE_TARGET_TYPE (VALUE_TYPE (arg2));
              if (domain_type != basetype)
                  arg2 = value_cast(lookup_pointer_type (domain_type), arg2);
              basetype = TYPE_VPTR_BASETYPE (domain_type);
              for (i = TYPE_NFN_FIELDS (basetype) - 1; i >= 0; i--)
                {
                  struct fn_field *f = TYPE_FN_FIELDLIST1 (basetype, i);
                  /* If one is virtual, then all are virtual.  */
                  if (TYPE_FN_FIELD_VIRTUAL_P (f, 0))
                    for (j = TYPE_FN_FIELDLIST_LENGTH (basetype, i) - 1; j >= 0; --j)
                      if (TYPE_FN_FIELD_VOFFSET (f, j) == fnoffset)
                        {
                          value_ptr temp = value_ind (arg2);
                          arg1 = value_virtual_fn_field (&temp, f, j, domain_type, 0);
                          arg2 = value_addr (temp);
                          goto got_it;
                        }
                }
              if (i < 0)
                error ("virtual function at index %d not found", fnoffset);
            }
          else
            {
              VALUE_TYPE (arg1) = lookup_pointer_type (TYPE_TARGET_TYPE (VALUE_TYPE (arg1)));
            }
        got_it:

          /* Now, say which argument to start evaluating from */
          tem = 2;
        }
      else if (op == STRUCTOP_STRUCT || op == STRUCTOP_PTR)
        {
          /* Hair for method invocations */
          int tem2;

          nargs = longest_to_int (exp->elts[pc + 1].longconst) + 1;
          /* First, evaluate the structure into arg2 */
          pc2 = (*pos)++;
          tem2 = longest_to_int (exp->elts[pc2 + 1].longconst);
          *pos += 3 + BYTES_TO_EXP_ELEM (tem2 + 1);
          if (noside == EVAL_SKIP)
            goto nosideret;

          if (op == STRUCTOP_STRUCT)
            {
              /* If v is a variable in a register, and the user types
                 v.method (), this will produce an error, because v has
                 no address.

                 A possible way around this would be to allocate a
                 copy of the variable on the stack, copy in the
                 contents, call the function, and copy out the
                 contents.  I.e. convert this from call by reference
                 to call by copy-return (or whatever it's called).
                 However, this does not work because it is not the
                 same: the method being called could stash a copy of
                 the address, and then future uses through that address
                 (after the method returns) would be expected to
                 use the variable itself, not some copy of it.  */
              arg2 = evaluate_subexp_for_address (exp, pos, noside);
            }
          else
            {
              arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
            }
          /* Now, say which argument to start evaluating from */
          tem = 2;
        }
      else
        {
          nargs = longest_to_int (exp->elts[pc + 1].longconst);
          tem = 0;
        }
      /* Allocate arg vector, including space for the function to be
         called in argvec[0] and a terminating NULL */
      argvec = (value_ptr *) alloca (sizeof (value_ptr) * (nargs + 2));
      for (; tem <= nargs; tem++)
        /* Ensure that array expressions are coerced into pointer objects. */
        argvec[tem] = evaluate_subexp_with_coercion (exp, pos, noside);

      /* signal end of arglist */
      argvec[tem] = 0;

      if (op == STRUCTOP_STRUCT || op == STRUCTOP_PTR)
        {
          int static_memfuncp;
          value_ptr temp = arg2;
          char tstr[64];

          argvec[1] = arg2;
          argvec[0] = 0;
          strcpy(tstr, &exp->elts[pc2+2].string);
          if (!argvec[0]) 
            {
              temp = arg2;
              argvec[0] =
              value_struct_elt (&temp, argvec+1, tstr,
                              &static_memfuncp,
                              op == STRUCTOP_STRUCT
                              ? "structure" : "structure pointer");
            }
          arg2 = value_from_longest (lookup_pointer_type(VALUE_TYPE (temp)),
                         VALUE_ADDRESS (temp)+VALUE_OFFSET (temp));
          argvec[1] = arg2;

          if (static_memfuncp)
            {
              argvec[1] = argvec[0];
              nargs--;
              argvec++;
            }
        }
      else if (op == STRUCTOP_MEMBER || op == STRUCTOP_MPTR)
        {
          argvec[1] = arg2;
          argvec[0] = arg1;
        }

      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        {
          /* If the return type doesn't look like a function type, call an
             error.  This can happen if somebody tries to turn a variable into
             a function call. This is here because people often want to
             call, eg, strcmp, which gdb doesn't know is a function.  If
             gdb isn't asked for it's opinion (ie. through "whatis"),
             it won't offer it. */

          struct type *ftype =
            TYPE_TARGET_TYPE (VALUE_TYPE (argvec[0]));

          if (ftype)
            return allocate_value (TYPE_TARGET_TYPE (VALUE_TYPE (argvec[0])));
          else
            error ("Expression of type other than \"Function returning ...\" used as function");
        }
      return call_function_by_hand (argvec[0], nargs, argvec + 1);

    case OP_F77_UNDETERMINED_ARGLIST: 

      tmp_pos = pc; /* Point to this instr */ 

      /* Remember that in F77, functions, substring ops and 
         array subscript operations cannot be disambiguated 
         at parse time.  We have made all array subscript operations, 
         substring operations as well as function calls  come here 
         and we now have to discover what the heck this thing actually was.  
         If it is an array, we massage it into a form that the 
         MULTI_F77_SUBSCRIPT operator can deal with. If it is 
         a function, we process just as if we got an OP_FUNCALL and 
         for a subscring operation, we perform the appropriate 
         substring operation.  */ 

      /* First get the nargs and then jump all the way over the:
         
         OP_UNDETERMINED_ARGLIST
         nargs 
         OP_UNDETERMINED_ARGLIST 
            
         instruction sequence */

      nargs = longest_to_int (exp->elts[tmp_pos+1].longconst);
      tmp_pos += 3; /* size(op_funcall) == 3 elts */ 

      /* We will always have an OP_VAR_VALUE as the next opcode. 
         The data stored after the OP_VAR_VALUE is the a pointer 
         to the function/array/string symbol.  We should now check and 
         make sure that the symbols is an array and not a function.  
         If it is an array type, we have hit a F77 subscript operation and 
         we have to do some magic. If it is not an array, we check 
         to see if we found a string here. If there is a string, 
         we recursively evaluate and let OP_f77_SUBSTR deal with 
         things.  If there is no string, we know there is a function 
         call at hand and change OP_FUNCALL_OR_SUBSCRIPT -> OP_FUNCALL.  
         In all cases, we recursively evaluate.  */ 

      /* First determine the type code we are dealing with.  */ 

      switch (exp->elts[tmp_pos].opcode)
        {
        case OP_VAR_VALUE: 
          tmp_pos += 1; /* To get to the symbol ptr */ 
          tmp_symbol = exp->elts[tmp_pos].symbol; 
          code = TYPE_CODE (SYMBOL_TYPE (tmp_symbol)); 
          break; 

        case OP_INTERNALVAR:
          tmp_pos += 1;
          var = exp->elts[tmp_pos].internalvar; 
          code = TYPE_CODE(VALUE_TYPE(var->value)); 
          break; 

        case OP_F77_UNDETERMINED_ARGLIST:
          /* Special case when you do stuff like print ARRAY(1,1)(3:4) */ 
          tmp1_pos = tmp_pos ; 
          arg2 = evaluate_subexp (NULL_TYPE, exp, &tmp1_pos, noside);
          code =TYPE_CODE (VALUE_TYPE (arg2)); 
          break; 

        default:
          error ("Cannot perform substring on this type"); 
        }                

      switch (code) 
        {
        case TYPE_CODE_ARRAY: 
          /* Transform this into what it really is: a MULTI_F77_SUBSCRIPT */
          tmp_pos = pc; 
          exp->elts[tmp_pos].opcode = MULTI_F77_SUBSCRIPT;
          exp->elts[tmp_pos+2].opcode = MULTI_F77_SUBSCRIPT; 
          break;

        case TYPE_CODE_LITERAL_STRING:  /* When substring'ing internalvars */ 
        case TYPE_CODE_STRING:
          tmp_pos = pc; 
          exp->elts[tmp_pos].opcode = OP_F77_SUBSTR; 
          exp->elts[tmp_pos+2].opcode = OP_F77_SUBSTR; 
          break;

        case TYPE_CODE_PTR:
        case TYPE_CODE_FUNC:
          /* This is just a regular OP_FUNCALL, transform it 
             and recursively evaluate */ 
          tmp_pos = pc; /* Point to OP_FUNCALL_OR_SUBSCRIPT */ 
          exp->elts[tmp_pos].opcode = OP_FUNCALL; 
          exp->elts[tmp_pos+2].opcode = OP_FUNCALL; 
          break; 

        default:
              error ("Cannot perform substring on this type"); 
        }

      /* Pretend like you never saw this expression */
      *pos -= 1; 
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      return arg2;   

    case OP_F77_SUBSTR:
      /* We have a substring operation on our hands here, 
         let us get the string we will be dealing with */

      (*pos) += 2;
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);

      /* Now evaluate the 'from' and 'to' */

      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);

      if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_INT)
         error ("Substring arguments must be of type integer");

      arg3 = evaluate_subexp_with_coercion (exp, pos, noside);

      if (TYPE_CODE (VALUE_TYPE (arg3)) != TYPE_CODE_INT)
         error ("Substring arguments must be of type integer");

      tem2 = *((int *) VALUE_CONTENTS_RAW (arg2)); 
      tem3 = *((int *) VALUE_CONTENTS_RAW (arg3)); 

      if ((tem2 < 1) || (tem2 > tem3))
         error ("Bad 'from' value %d on substring operation", tem2); 

      if ((tem3 < tem2) || (tem3 > (TYPE_LENGTH (VALUE_TYPE (arg1)))))
         error ("Bad 'to' value %d on substring operation", tem3); 
      
      if (noside == EVAL_SKIP)
        goto nosideret;
      
      return f77_value_substring (arg1, tem2, tem3);

    case OP_F77_LITERAL_COMPLEX:
      /* We have a complex number, There should be 2 floating 
         point numbers that compose it */ 
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside); 

      /* Complex*16 is the default size to create */ 
      return f77_value_literal_complex (arg1, arg2, 16);

    case STRUCTOP_STRUCT:
      tem = longest_to_int (exp->elts[pc + 1].longconst);
      (*pos) += 3 + BYTES_TO_EXP_ELEM (tem + 1);
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        return value_zero (lookup_struct_elt_type (VALUE_TYPE (arg1),
                                                   &exp->elts[pc + 2].string,
                                                   0),
                           lval_memory);
      else
        {
          value_ptr temp = arg1;
          return value_struct_elt (&temp, NULL, &exp->elts[pc + 2].string,
                                   NULL, "structure");
        }

    case STRUCTOP_PTR:
      tem = longest_to_int (exp->elts[pc + 1].longconst);
      (*pos) += 3 + BYTES_TO_EXP_ELEM (tem + 1);
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        return value_zero (lookup_struct_elt_type (VALUE_TYPE (arg1),
                                                   &exp->elts[pc + 2].string,
                                                   0),
                           lval_memory);
      else
        {
          value_ptr temp = arg1;
          return value_struct_elt (&temp, NULL, &exp->elts[pc + 2].string,
                                   NULL, "structure pointer");
        }

    case STRUCTOP_MEMBER:
      arg1 = evaluate_subexp_for_address (exp, pos, noside);
      goto handle_pointer_to_member;
    case STRUCTOP_MPTR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
    handle_pointer_to_member:
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_PTR)
        goto bad_pointer_to_member;
      type = TYPE_TARGET_TYPE (VALUE_TYPE (arg2));
      if (TYPE_CODE (type) == TYPE_CODE_METHOD)
        error ("not implemented: pointer-to-method in pointer-to-member construct");
      if (TYPE_CODE (type) != TYPE_CODE_MEMBER)
        goto bad_pointer_to_member;
      /* Now, convert these values to an address.  */
      arg1 = value_cast (lookup_pointer_type (TYPE_DOMAIN_TYPE (type)),
                         arg1);
      arg3 = value_from_longest (lookup_pointer_type (TYPE_TARGET_TYPE (type)),
                                 value_as_long (arg1) + value_as_long (arg2));
      return value_ind (arg3);
    bad_pointer_to_member:
      error("non-pointer-to-member value used in pointer-to-member construct");

    case BINOP_CONCAT:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, op, OP_NULL);
      else
        return value_concat (arg1, arg2);

    case BINOP_ASSIGN:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
        return arg1;
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, op, OP_NULL);
      else
        return value_assign (arg1, arg2);

    case BINOP_ASSIGN_MODIFY:
      (*pos) += 2;
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
        return arg1;
      op = exp->elts[pc + 1].opcode;
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, BINOP_ASSIGN_MODIFY, op);
      else if (op == BINOP_ADD)
        arg2 = value_add (arg1, arg2);
      else if (op == BINOP_SUB)
        arg2 = value_sub (arg1, arg2);
      else
        arg2 = value_binop (arg1, arg2, op);
      return value_assign (arg1, arg2);

    case BINOP_ADD:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, op, OP_NULL);
      else
        return value_add (arg1, arg2);

    case BINOP_SUB:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, op, OP_NULL);
      else
        return value_sub (arg1, arg2);

    case BINOP_MUL:
    case BINOP_DIV:
    case BINOP_REM:
    case BINOP_MOD:
    case BINOP_LSH:
    case BINOP_RSH:
    case BINOP_BITWISE_AND:
    case BINOP_BITWISE_IOR:
    case BINOP_BITWISE_XOR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, op, OP_NULL);
      else
        if (noside == EVAL_AVOID_SIDE_EFFECTS
            && (op == BINOP_DIV || op == BINOP_REM || op == BINOP_MOD))
          return value_zero (VALUE_TYPE (arg1), not_lval);
      else
        return value_binop (arg1, arg2, op);

    case BINOP_SUBSCRIPT:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        {
          /* If the user attempts to subscript something that has no target
             type (like a plain int variable for example), then report this
             as an error. */

          type = TYPE_TARGET_TYPE (VALUE_TYPE (arg1));
          if (type)
            return value_zero (type, VALUE_LVAL (arg1));
          else
            error ("cannot subscript something of type `%s'",
                   TYPE_NAME (VALUE_TYPE (arg1)));
        }
                           
      if (binop_user_defined_p (op, arg1, arg2))
        return value_x_binop (arg1, arg2, op, OP_NULL);
      else
        return value_subscript (arg1, arg2);

    case BINOP_IN:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      return value_in (arg1, arg2);
      
    case MULTI_SUBSCRIPT:
      (*pos) += 2;
      nargs = longest_to_int (exp->elts[pc + 1].longconst);
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      while (nargs-- > 0)
        {
          arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
          /* FIXME:  EVAL_SKIP handling may not be correct. */
          if (noside == EVAL_SKIP)
            {
              if (nargs > 0)
                {
                  continue;
                }
              else
                {
                  goto nosideret;
                }
            }
          /* FIXME:  EVAL_AVOID_SIDE_EFFECTS handling may not be correct. */
          if (noside == EVAL_AVOID_SIDE_EFFECTS)
            {
              /* If the user attempts to subscript something that has no target
                 type (like a plain int variable for example), then report this
                 as an error. */
              
              type = TYPE_TARGET_TYPE (VALUE_TYPE (arg1));
              if (type != NULL)
                {
                  arg1 = value_zero (type, VALUE_LVAL (arg1));
                  noside = EVAL_SKIP;
                  continue;
                }
              else
                {
                  error ("cannot subscript something of type `%s'",
                         TYPE_NAME (VALUE_TYPE (arg1)));
                }
            }
          
          if (binop_user_defined_p (op, arg1, arg2))
            {
              arg1 = value_x_binop (arg1, arg2, op, OP_NULL);
            }
          else
            {
              arg1 = value_subscript (arg1, arg2);
            }
        }
      return (arg1);

    case MULTI_F77_SUBSCRIPT:
      { 
        int subscript_array[MAX_FORTRAN_DIMS+1]; /* 1-based array of 
                                                    subscripts, max == 7 */
        int array_size_array[MAX_FORTRAN_DIMS+1];
        int ndimensions=1,i;
        struct type *tmp_type; 
        int offset_item;   /* The array offset where the item lives */ 
        int fixed_subscript; 

        (*pos) += 2;
        nargs = longest_to_int (exp->elts[pc + 1].longconst);
         
        if (nargs > MAX_FORTRAN_DIMS)
          error ("Too many subscripts for F77 (%d Max)", MAX_FORTRAN_DIMS);

        arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
         
        ndimensions = calc_f77_array_dims (VALUE_TYPE (arg1)); 

        if (nargs != ndimensions)
          error ("Wrong number of subscripts");

        /* Now that we know we have a legal array subscript expression 
           let us actually find out where this element exists in the array. */ 

        tmp_type = VALUE_TYPE (arg1);
        offset_item = 0; 
        for (i = 1; i <= nargs; i++)
          {
            /* Evaluate each subscript, It must be a legal integer in F77 */ 
            arg2 = evaluate_subexp_with_coercion (exp, pos, noside);

            if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_INT)
              error ("Array subscripts must be of type integer");

            /* Fill in the subscript and array size arrays */ 

            subscript_array[i] = (* (unsigned int *) VALUE_CONTENTS(arg2)); 
               
            retcode = f77_get_dynamic_upperbound (tmp_type, &upper);
            if (retcode == BOUND_FETCH_ERROR)
              error ("Cannot obtain dynamic upper bound"); 

            retcode = f77_get_dynamic_lowerbound (tmp_type, &lower); 
            if (retcode == BOUND_FETCH_ERROR)
              error("Cannot obtain dynamic lower bound"); 

            array_size_array[i] = upper - lower + 1;
               
            /* Zero-normalize subscripts so that offsetting will work. */ 
               
            subscript_array[i] -= lower;

            /* If we are at the bottom of a multidimensional 
               array type then keep a ptr to the last ARRAY
               type around for use when calling value_subscript()
               below. This is done because we pretend to value_subscript
               that we actually have a one-dimensional array 
               of base element type that we apply a simple 
               offset to. */ 

            if (i < nargs) 
              tmp_type = TYPE_TARGET_TYPE (tmp_type); 
          }

        /* Now let us calculate the offset for this item */

        offset_item = subscript_array[ndimensions]; 
         
        for (i = ndimensions - 1; i >= 1; i--)
          offset_item = 
            array_size_array[i] * offset_item + subscript_array[i];

        /* Construct a value node with the value of the offset */

        arg2 = value_from_longest (builtin_type_f_integer, offset_item); 

        /* Let us now play a dirty trick: we will take arg1 
           which is a value node pointing to the topmost level
           of the multidimensional array-set and pretend
           that it is actually a array of the final element 
           type, this will ensure that value_subscript()
           returns the correct type value */

        VALUE_TYPE (arg1) = tmp_type; 

        arg1 = value_subscript (arg1, arg2);
        return arg1;
      }

    case BINOP_LOGICAL_AND:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        {
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
          goto nosideret;
        }
      
      oldpos = *pos;
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
      *pos = oldpos;
      
      if (binop_user_defined_p (op, arg1, arg2)) 
        {
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_logical_not (arg1);
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos,
                                  (tem ? EVAL_SKIP : noside));
          return value_from_longest (builtin_type_int,
                                  (LONGEST) (!tem && !value_logical_not (arg2)));
        }

    case BINOP_LOGICAL_OR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        {
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
          goto nosideret;
        }
      
      oldpos = *pos;
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
      *pos = oldpos;
      
      if (binop_user_defined_p (op, arg1, arg2)) 
        {
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_logical_not (arg1);
          arg2 = evaluate_subexp (NULL_TYPE, exp, pos,
                                  (!tem ? EVAL_SKIP : noside));
          return value_from_longest (builtin_type_int,
                                  (LONGEST) (!tem || !value_logical_not (arg2)));
        }

    case BINOP_EQUAL:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        {
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_equal (arg1, arg2);
          return value_from_longest (builtin_type_int, (LONGEST) tem);
        }

    case BINOP_NOTEQUAL:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        {
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_equal (arg1, arg2);
          return value_from_longest (builtin_type_int, (LONGEST) ! tem);
        }

    case BINOP_LESS:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        {
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_less (arg1, arg2);
          return value_from_longest (builtin_type_int, (LONGEST) tem);
        }

    case BINOP_GTR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        {
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_less (arg2, arg1);
          return value_from_longest (builtin_type_int, (LONGEST) tem);
        }

    case BINOP_GEQ:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        {
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else
        {
          tem = value_less (arg2, arg1) || value_equal (arg1, arg2);
          return value_from_longest (builtin_type_int, (LONGEST) tem);
        }

    case BINOP_LEQ:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
        {
          return value_x_binop (arg1, arg2, op, OP_NULL);
        }
      else 
        {
          tem = value_less (arg1, arg2) || value_equal (arg1, arg2);
          return value_from_longest (builtin_type_int, (LONGEST) tem);
        }

    case BINOP_REPEAT:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_INT)
        error ("Non-integral right operand for \"@\" operator.");
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        return allocate_repeat_value (VALUE_TYPE (arg1),
                                      longest_to_int (value_as_long (arg2)));
      else
        return value_repeat (arg1, longest_to_int (value_as_long (arg2)));

    case BINOP_COMMA:
      evaluate_subexp (NULL_TYPE, exp, pos, noside);
      return evaluate_subexp (NULL_TYPE, exp, pos, noside);

    case UNOP_NEG:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (unop_user_defined_p (op, arg1))
        return value_x_unop (arg1, op);
      else
        return value_neg (arg1);

    case UNOP_COMPLEMENT:
      /* C++: check for and handle destructor names.  */
      op = exp->elts[*pos].opcode;

      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (unop_user_defined_p (UNOP_COMPLEMENT, arg1))
        return value_x_unop (arg1, UNOP_COMPLEMENT);
      else
        return value_complement (arg1);

    case UNOP_LOGICAL_NOT:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (unop_user_defined_p (op, arg1))
        return value_x_unop (arg1, op);
      else
        return value_from_longest (builtin_type_int,
                                   (LONGEST) value_logical_not (arg1));

    case UNOP_IND:
      if (expect_type && TYPE_CODE (expect_type) == TYPE_CODE_PTR)
        expect_type = TYPE_TARGET_TYPE (expect_type);
      arg1 = evaluate_subexp (expect_type, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        {
          if (TYPE_CODE (VALUE_TYPE (arg1)) == TYPE_CODE_PTR
              || TYPE_CODE (VALUE_TYPE (arg1)) == TYPE_CODE_REF
              /* In C you can dereference an array to get the 1st elt.  */
              || TYPE_CODE (VALUE_TYPE (arg1)) == TYPE_CODE_ARRAY
              )
            return value_zero (TYPE_TARGET_TYPE (VALUE_TYPE (arg1)),
                               lval_memory);
          else if (TYPE_CODE (VALUE_TYPE (arg1)) == TYPE_CODE_INT)
            /* GDB allows dereferencing an int.  */
            return value_zero (builtin_type_int, lval_memory);
          else
            error ("Attempt to take contents of a non-pointer value.");
        }
      return value_ind (arg1);

    case UNOP_ADDR:
      /* C++: check for and handle pointer to members.  */
      
      op = exp->elts[*pos].opcode;

      if (noside == EVAL_SKIP)
        {
          if (op == OP_SCOPE)
            {
              int temm = longest_to_int (exp->elts[pc+3].longconst);
              (*pos) += 3 + BYTES_TO_EXP_ELEM (temm + 1);
            }
          else
            evaluate_subexp (expect_type, exp, pos, EVAL_SKIP);
          goto nosideret;
        }

      return evaluate_subexp_for_address (exp, pos, noside);

    case UNOP_SIZEOF:
      if (noside == EVAL_SKIP)
        {
          evaluate_subexp (NULL_TYPE, exp, pos, EVAL_SKIP);
          goto nosideret;
        }
      return evaluate_subexp_for_sizeof (exp, pos);

    case UNOP_CAST:
      (*pos) += 2;
      type = exp->elts[pc + 1].type;
      arg1 = evaluate_subexp (type, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (type != VALUE_TYPE (arg1))
        arg1 = value_cast (type, arg1);
      return arg1;

    case UNOP_MEMVAL:
      (*pos) += 2;
      arg1 = evaluate_subexp (expect_type, exp, pos, noside);
      if (noside == EVAL_SKIP)
        goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        return value_zero (exp->elts[pc + 1].type, lval_memory);
      else
        return value_at_lazy (exp->elts[pc + 1].type,
                              value_as_pointer (arg1));

    case UNOP_PREINCREMENT:
      arg1 = evaluate_subexp (expect_type, exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
        return arg1;
      else if (unop_user_defined_p (op, arg1))
        {
          return value_x_unop (arg1, op);
        }
      else
        {
          arg2 = value_add (arg1, value_from_longest (builtin_type_char, 
                                                   (LONGEST) 1));
          return value_assign (arg1, arg2);
        }

    case UNOP_PREDECREMENT:
      arg1 = evaluate_subexp (expect_type, exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
        return arg1;
      else if (unop_user_defined_p (op, arg1))
        {
          return value_x_unop (arg1, op);
        }
      else
        {
          arg2 = value_sub (arg1, value_from_longest (builtin_type_char, 
                                                   (LONGEST) 1));
          return value_assign (arg1, arg2);
        }

    case UNOP_POSTINCREMENT:
      arg1 = evaluate_subexp (expect_type, exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
        return arg1;
      else if (unop_user_defined_p (op, arg1))
        {
          return value_x_unop (arg1, op);
        }
      else
        {
          arg2 = value_add (arg1, value_from_longest (builtin_type_char, 
                                                   (LONGEST) 1));
          value_assign (arg1, arg2);
          return arg1;
        }

    case UNOP_POSTDECREMENT:
      arg1 = evaluate_subexp (expect_type, exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
        return arg1;
      else if (unop_user_defined_p (op, arg1))
        {
          return value_x_unop (arg1, op);
        }
      else
        {
          arg2 = value_sub (arg1, value_from_longest (builtin_type_char, 
                                                   (LONGEST) 1));
          value_assign (arg1, arg2);
          return arg1;
        }
        
    case OP_THIS:
      (*pos) += 1;
      return value_of_this (1);

    case OP_TYPE:
      error ("Attempt to use a type name as an expression");

    default:
      /* Removing this case and compiling with gcc -Wall reveals that
         a lot of cases are hitting this case.  Some of these should
         probably be removed from expression.h (e.g. do we need a BINOP_SCOPE
         and an OP_SCOPE?); others are legitimate expressions which are
         (apparently) not fully implemented.

         If there are any cases landing here which mean a user error,
         then they should be separate cases, with more descriptive
         error messages.  */

      error ("\
GDB does not (yet) know how to evaluate that kind of expression");
    }

 nosideret:
  return value_from_longest (builtin_type_long, (LONGEST) 1);
}
\f
/* Evaluate a subexpression of EXP, at index *POS,
   and return the address of that subexpression.
   Advance *POS over the subexpression.
   If the subexpression isn't an lvalue, get an error.
   NOSIDE may be EVAL_AVOID_SIDE_EFFECTS;
   then only the type of the result need be correct.  */

static value_ptr
evaluate_subexp_for_address (exp, pos, noside)
     register struct expression *exp;
     register int *pos;
     enum noside noside;
{
  enum exp_opcode op;
  register int pc;
  struct symbol *var;

  pc = (*pos);
  op = exp->elts[pc].opcode;

  switch (op)
    {
    case UNOP_IND:
      (*pos)++;
      return evaluate_subexp (NULL_TYPE, exp, pos, noside);

    case UNOP_MEMVAL:
      (*pos) += 3;
      return value_cast (lookup_pointer_type (exp->elts[pc + 1].type),
                         evaluate_subexp (NULL_TYPE, exp, pos, noside));

    case OP_VAR_VALUE:
      var = exp->elts[pc + 2].symbol;

      /* C++: The "address" of a reference should yield the address
       * of the object pointed to. Let value_addr() deal with it. */
      if (TYPE_CODE (SYMBOL_TYPE (var)) == TYPE_CODE_REF)
        goto default_case;

      (*pos) += 4;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        {
          struct type *type =
            lookup_pointer_type (SYMBOL_TYPE (var));
          enum address_class sym_class = SYMBOL_CLASS (var);

          if (sym_class == LOC_CONST
              || sym_class == LOC_CONST_BYTES
              || sym_class == LOC_REGISTER
              || sym_class == LOC_REGPARM)
            error ("Attempt to take address of register or constant.");

        return
          value_zero (type, not_lval);
        }
      else
        return
          locate_var_value
            (var,
             block_innermost_frame (exp->elts[pc + 1].block));

    default:
    default_case:
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
        {
          value_ptr x = evaluate_subexp (NULL_TYPE, exp, pos, noside);
          if (VALUE_LVAL (x) == lval_memory)
            return value_zero (lookup_pointer_type (VALUE_TYPE (x)),
                               not_lval);
          else
            error ("Attempt to take address of non-lval");
        }
      return value_addr (evaluate_subexp (NULL_TYPE, exp, pos, noside));
    }
}

/* Evaluate like `evaluate_subexp' except coercing arrays to pointers.
   When used in contexts where arrays will be coerced anyway, this is
   equivalent to `evaluate_subexp' but much faster because it avoids
   actually fetching array contents (perhaps obsolete now that we have
   VALUE_LAZY).

   Note that we currently only do the coercion for C expressions, where
   arrays are zero based and the coercion is correct.  For other languages,
   with nonzero based arrays, coercion loses.  Use CAST_IS_CONVERSION
   to decide if coercion is appropriate.

   */

static value_ptr
evaluate_subexp_with_coercion (exp, pos, noside)
     register struct expression *exp;
     register int *pos;
     enum noside noside;
{
  register enum exp_opcode op;
  register int pc;
  register value_ptr val;
  struct symbol *var;

  pc = (*pos);
  op = exp->elts[pc].opcode;

  switch (op)
    {
    case OP_VAR_VALUE:
      var = exp->elts[pc + 2].symbol;
      if (TYPE_CODE (SYMBOL_TYPE (var)) == TYPE_CODE_ARRAY
          && CAST_IS_CONVERSION)
        {
          (*pos) += 4;
          val =
            locate_var_value
              (var, block_innermost_frame (exp->elts[pc + 1].block));
          return value_cast (lookup_pointer_type (TYPE_TARGET_TYPE (SYMBOL_TYPE (var))),
                             val);
        }
      /* FALLTHROUGH */

    default:
      return evaluate_subexp (NULL_TYPE, exp, pos, noside);
    }
}

/* Evaluate a subexpression of EXP, at index *POS,
   and return a value for the size of that subexpression.
   Advance *POS over the subexpression.  */

static value_ptr
evaluate_subexp_for_sizeof (exp, pos)
     register struct expression *exp;
     register int *pos;
{
  enum exp_opcode op;
  register int pc;
  value_ptr val;

  pc = (*pos);
  op = exp->elts[pc].opcode;

  switch (op)
    {
      /* This case is handled specially
         so that we avoid creating a value for the result type.
         If the result type is very big, it's desirable not to
         create a value unnecessarily.  */
    case UNOP_IND:
      (*pos)++;
      val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
      return value_from_longest (builtin_type_int, (LONGEST)
                      TYPE_LENGTH (TYPE_TARGET_TYPE (VALUE_TYPE (val))));

    case UNOP_MEMVAL:
      (*pos) += 3;
      return value_from_longest (builtin_type_int, 
                              (LONGEST) TYPE_LENGTH (exp->elts[pc + 1].type));

    case OP_VAR_VALUE:
      (*pos) += 4;
      return
        value_from_longest
          (builtin_type_int,
           (LONGEST) TYPE_LENGTH (SYMBOL_TYPE (exp->elts[pc + 2].symbol)));

    default:
      val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
      return value_from_longest (builtin_type_int,
                              (LONGEST) TYPE_LENGTH (VALUE_TYPE (val)));
    }
}

/* Parse a type expression in the string [P..P+LENGTH). */

struct type *
parse_and_eval_type (p, length)
     char *p;
     int length;
{
    char *tmp = (char *)alloca (length + 4);
    struct expression *expr;
    tmp[0] = '(';
    memcpy (tmp+1, p, length);
    tmp[length+1] = ')';
    tmp[length+2] = '0';
    tmp[length+3] = '\0';
    expr = parse_expression (tmp);
    if (expr->elts[0].opcode != UNOP_CAST)
        error ("Internal error in eval_type.");
    return expr->elts[1].type;
}

int
calc_f77_array_dims (array_type)
     struct type *array_type;
{
  int ndimen = 1;
  struct type *tmp_type;

  if ((TYPE_CODE(array_type) != TYPE_CODE_ARRAY))
    error ("Can't get dimensions for a non-array type");
   
  tmp_type = array_type; 

  while (tmp_type = TYPE_TARGET_TYPE (tmp_type))
    {
      if (TYPE_CODE (tmp_type) == TYPE_CODE_ARRAY)
        ++ndimen;
    }
  return ndimen; 
}