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binutils-gdb/gdb/eval.c
gdb-3.4 1c997a4ae8 gdb-3.4
2012-06-03 15:36:32 +01:00

1022 lines
29 KiB
C
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/* Evaluate expressions for GDB.
Copyright (C) 1986, 1987, 1989 Free Software Foundation, Inc.
This file is part of GDB.
GDB 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 1, or (at your option)
any later version.
GDB 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 GDB; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "defs.h"
#include "param.h"
#include "symtab.h"
#include "value.h"
#include "expression.h"
/* 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_c_expression (exp);
register CORE_ADDR addr;
register struct cleanup *old_chain
= make_cleanup (free_current_contents, &expr);
addr = (CORE_ADDR) value_as_long (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_c_1 (expptr, 0, 0);
register CORE_ADDR addr;
register struct cleanup *old_chain
= make_cleanup (free_current_contents, &expr);
addr = value_as_long (evaluate_expression (expr));
do_cleanups (old_chain);
return addr;
}
value
parse_and_eval (exp)
char *exp;
{
struct expression *expr = parse_c_expression (exp);
register value 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
parse_to_comma_and_eval (expp)
char **expp;
{
struct expression *expr = parse_c_1 (expp, 0, 1);
register value val;
register struct cleanup *old_chain
= make_cleanup (free_current_contents, &expr);
val = evaluate_expression (expr);
do_cleanups (old_chain);
return val;
}
/* Evaluate an expression in internal prefix form
such as is constructed by expread.y.
See expression.h for info on the format of an expression. */
static value evaluate_subexp ();
static value evaluate_subexp_for_address ();
static value evaluate_subexp_for_sizeof ();
static value evaluate_subexp_with_coercion ();
/* 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). */
};
value
evaluate_expression (exp)
struct expression *exp;
{
int pc = 0;
return evaluate_subexp (0, exp, &pc, EVAL_NORMAL);
}
/* Evaluate an expression, avoiding all memory references
and getting a value whose type alone is correct. */
value
evaluate_type (exp)
struct expression *exp;
{
int pc = 0;
return evaluate_subexp (0, exp, &pc, EVAL_AVOID_SIDE_EFFECTS);
}
static value
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;
register int pc, pc2, oldpos;
register value arg1, arg2, arg3;
int nargs;
value *argvec;
pc = (*pos)++;
op = exp->elts[pc].opcode;
switch (op)
{
case OP_SCOPE:
tem = strlen (&exp->elts[pc + 2].string);
(*pos) += 3 + ((tem + sizeof (union exp_element))
/ sizeof (union exp_element));
return value_static_field (exp->elts[pc + 1].type,
&exp->elts[pc + 2].string, -1);
case OP_LONG:
(*pos) += 3;
return value_from_long (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) += 2;
if (noside == EVAL_SKIP)
goto nosideret;
if (noside == EVAL_AVOID_SIDE_EFFECTS)
{
struct symbol * sym = exp->elts[pc + 1].symbol;
enum lval_type lv;
switch (SYMBOL_CLASS (sym))
{
case LOC_CONST:
case LOC_LABEL:
case LOC_CONST_BYTES:
lv = not_lval;
case LOC_REGISTER:
case LOC_REGPARM:
lv = lval_register;
default:
lv = lval_memory;
}
return value_zero (SYMBOL_TYPE (sym), lv);
}
else
return value_of_variable (exp->elts[pc + 1].symbol);
case OP_LAST:
(*pos) += 2;
return access_value_history ((int) exp->elts[pc + 1].longconst);
case OP_REGISTER:
(*pos) += 2;
return value_of_register ((int) exp->elts[pc + 1].longconst);
case OP_INTERNALVAR:
(*pos) += 2;
return value_of_internalvar (exp->elts[pc + 1].internalvar);
case OP_STRING:
tem = strlen (&exp->elts[pc + 1].string);
(*pos) += 2 + ((tem + sizeof (union exp_element))
/ sizeof (union exp_element));
if (noside == EVAL_SKIP)
goto nosideret;
return value_string (&exp->elts[pc + 1].string, tem);
case TERNOP_COND:
/* Skip third and second args to evaluate the first one. */
arg1 = evaluate_subexp (0, exp, pos, noside);
if (value_zerop (arg1))
{
evaluate_subexp (0, exp, pos, EVAL_SKIP);
return evaluate_subexp (0, exp, pos, noside);
}
else
{
arg2 = evaluate_subexp (0, exp, pos, noside);
evaluate_subexp (0, exp, pos, EVAL_SKIP);
return arg2;
}
case OP_FUNCALL:
(*pos) += 2;
op = exp->elts[*pos].opcode;
if (op == STRUCTOP_MEMBER || op == STRUCTOP_MPTR)
{
int fnptr;
int tem2;
nargs = (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 (0, 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 (0, exp, pos, noside);
fnptr = (int) value_as_long (arg1);
if (fnptr < 128)
{
struct type *basetype;
int i, j;
basetype = TYPE_TARGET_TYPE (VALUE_TYPE (arg2));
basetype = TYPE_VPTR_BASETYPE (basetype);
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) == fnptr)
{
value vtbl;
value base = value_ind (arg2);
struct type *fntype = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));
if (TYPE_VPTR_FIELDNO (basetype) < 0)
TYPE_VPTR_FIELDNO (basetype)
= fill_in_vptr_fieldno (basetype);
VALUE_TYPE (base) = basetype;
vtbl = value_field (base, TYPE_VPTR_FIELDNO (basetype));
VALUE_TYPE (vtbl) = lookup_pointer_type (fntype);
VALUE_TYPE (arg1) = builtin_type_int;
arg1 = value_subscript (vtbl, arg1);
VALUE_TYPE (arg1) = fntype;
goto got_it;
}
}
if (i < 0)
error ("virtual function at index %d not found", fnptr);
}
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 = (int) exp->elts[pc + 1].longconst + 1;
/* First, evaluate the structure into arg2 */
pc2 = (*pos)++;
tem2 = strlen (&exp->elts[pc2 + 1].string);
*pos += 2 + (tem2 + sizeof (union exp_element)) / sizeof (union exp_element);
if (noside == EVAL_SKIP)
goto nosideret;
if (op == STRUCTOP_STRUCT)
{
arg2 = evaluate_subexp_for_address (exp, pos, noside);
}
else
{
arg2 = evaluate_subexp (0, exp, pos, noside);
}
/* Now, say which argument to start evaluating from */
tem = 2;
}
else
{
nargs = (int) exp->elts[pc + 1].longconst;
tem = 0;
}
argvec = (value *) alloca (sizeof (value) * (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;
argvec[1] = arg2;
argvec[0] =
value_struct_elt (arg2, argvec+1, &exp->elts[pc2 + 1].string,
&static_memfuncp,
op == STRUCTOP_STRUCT
? "structure" : "structure pointer");
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 (argvec[0], nargs, argvec + 1);
case STRUCTOP_STRUCT:
tem = strlen (&exp->elts[pc + 1].string);
(*pos) += 2 + ((tem + sizeof (union exp_element))
/ sizeof (union exp_element));
arg1 = evaluate_subexp (0, 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 + 1].string),
lval_memory);
else
return value_struct_elt (arg1, 0, &exp->elts[pc + 1].string, 0,
"structure");
case STRUCTOP_PTR:
tem = strlen (&exp->elts[pc + 1].string);
(*pos) += 2 + (tem + sizeof (union exp_element)) / sizeof (union exp_element);
arg1 = evaluate_subexp (0, exp, pos, noside);
if (noside == EVAL_SKIP)
goto nosideret;
if (noside == EVAL_AVOID_SIDE_EFFECTS)
return value_zero (lookup_struct_elt_type (TYPE_TARGET_TYPE
(VALUE_TYPE (arg1)),
&exp->elts[pc + 1].string),
lval_memory);
else
return value_struct_elt (arg1, 0, &exp->elts[pc + 1].string, 0,
"structure pointer");
case STRUCTOP_MEMBER:
arg1 = evaluate_subexp_for_address (exp, pos, noside);
arg2 = evaluate_subexp (0, exp, pos, noside);
if (noside == EVAL_SKIP)
goto nosideret;
/* Now, convert these values to an address. */
if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_PTR
|| ((TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (arg2)))
!= TYPE_CODE_MEMBER)
&& (TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (arg2)))
!= TYPE_CODE_METHOD)))
error ("non-pointer-to-member value used in pointer-to-member construct");
arg3 = value_from_long (builtin_type_long,
value_as_long (arg1) + value_as_long (arg2));
VALUE_TYPE (arg3) =
lookup_pointer_type (TYPE_TARGET_TYPE (TYPE_TARGET_TYPE (VALUE_TYPE (arg2))));
return value_ind (arg3);
case STRUCTOP_MPTR:
arg1 = evaluate_subexp (0, exp, pos, noside);
arg2 = evaluate_subexp (0, exp, pos, noside);
if (noside == EVAL_SKIP)
goto nosideret;
/* Now, convert these values to an address. */
if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_PTR
|| (TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (arg2))) != TYPE_CODE_MEMBER
&& TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (arg2))) != TYPE_CODE_METHOD))
error ("non-pointer-to-member value used in pointer-to-member construct");
arg3 = value_from_long (builtin_type_long,
value_as_long (arg1) + value_as_long (arg2));
VALUE_TYPE (arg3) =
lookup_pointer_type (TYPE_TARGET_TYPE (TYPE_TARGET_TYPE (VALUE_TYPE (arg2))));
return value_ind (arg3);
case BINOP_ASSIGN:
arg1 = evaluate_subexp (0, 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, 0);
else
return value_assign (arg1, arg2);
case BINOP_ASSIGN_MODIFY:
(*pos) += 2;
arg1 = evaluate_subexp (0, 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, 0);
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, 0);
else
return value_sub (arg1, arg2);
case BINOP_MUL:
case BINOP_DIV:
case BINOP_REM:
case BINOP_LSH:
case BINOP_RSH:
case BINOP_LOGAND:
case BINOP_LOGIOR:
case BINOP_LOGXOR:
arg1 = evaluate_subexp (0, exp, pos, noside);
arg2 = evaluate_subexp (0, exp, pos, noside);
if (noside == EVAL_SKIP)
goto nosideret;
if (binop_user_defined_p (op, arg1, arg2))
return value_x_binop (arg1, arg2, op, 0);
else
if (noside == EVAL_AVOID_SIDE_EFFECTS
&& op == BINOP_DIV)
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)
return value_zero (TYPE_TARGET_TYPE (VALUE_TYPE (arg1)),
VALUE_LVAL (arg1));
if (binop_user_defined_p (op, arg1, arg2))
return value_x_binop (arg1, arg2, op, 0);
else
return value_subscript (arg1, arg2);
case BINOP_AND:
arg1 = evaluate_subexp (0, exp, pos, noside);
if (noside == EVAL_SKIP)
{
arg2 = evaluate_subexp (0, exp, pos, noside);
goto nosideret;
}
oldpos = *pos;
arg2 = evaluate_subexp (0, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
*pos = oldpos;
if (binop_user_defined_p (op, arg1, arg2))
{
arg2 = evaluate_subexp (0, exp, pos, noside);
return value_x_binop (arg1, arg2, op, 0);
}
else
{
tem = value_zerop (arg1);
arg2 = evaluate_subexp (0, exp, pos,
(tem ? EVAL_SKIP : noside));
return value_from_long (builtin_type_int,
(LONGEST) (!tem && !value_zerop (arg2)));
}
case BINOP_OR:
arg1 = evaluate_subexp (0, exp, pos, noside);
if (noside == EVAL_SKIP)
{
arg2 = evaluate_subexp (0, exp, pos, noside);
goto nosideret;
}
oldpos = *pos;
arg2 = evaluate_subexp (0, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
*pos = oldpos;
if (binop_user_defined_p (op, arg1, arg2))
{
arg2 = evaluate_subexp (0, exp, pos, noside);
return value_x_binop (arg1, arg2, op, 0);
}
else
{
tem = value_zerop (arg1);
arg2 = evaluate_subexp (0, exp, pos,
(!tem ? EVAL_SKIP : noside));
return value_from_long (builtin_type_int,
(LONGEST) (!tem || !value_zerop (arg2)));
}
case BINOP_EQUAL:
arg1 = evaluate_subexp (0, 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, 0);
}
else
{
tem = value_equal (arg1, arg2);
return value_from_long (builtin_type_int, (LONGEST) tem);
}
case BINOP_NOTEQUAL:
arg1 = evaluate_subexp (0, 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, 0);
}
else
{
tem = value_equal (arg1, arg2);
return value_from_long (builtin_type_int, (LONGEST) ! tem);
}
case BINOP_LESS:
arg1 = evaluate_subexp (0, 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, 0);
}
else
{
tem = value_less (arg1, arg2);
return value_from_long (builtin_type_int, (LONGEST) tem);
}
case BINOP_GTR:
arg1 = evaluate_subexp (0, 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, 0);
}
else
{
tem = value_less (arg2, arg1);
return value_from_long (builtin_type_int, (LONGEST) tem);
}
case BINOP_GEQ:
arg1 = evaluate_subexp (0, 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, 0);
}
else
{
tem = value_less (arg1, arg2);
return value_from_long (builtin_type_int, (LONGEST) ! tem);
}
case BINOP_LEQ:
arg1 = evaluate_subexp (0, 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, 0);
}
else
{
tem = value_less (arg2, arg1);
return value_from_long (builtin_type_int, (LONGEST) ! tem);
}
case BINOP_REPEAT:
arg1 = evaluate_subexp (0, exp, pos, noside);
arg2 = evaluate_subexp (0, 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),
(int) value_as_long (arg2));
else
return value_repeat (arg1, (int) value_as_long (arg2));
case BINOP_COMMA:
evaluate_subexp (0, exp, pos, noside);
return evaluate_subexp (0, exp, pos, noside);
case UNOP_NEG:
arg1 = evaluate_subexp (0, 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_LOGNOT:
arg1 = evaluate_subexp (0, 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_lognot (arg1);
case UNOP_ZEROP:
arg1 = evaluate_subexp (0, 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_long (builtin_type_int,
(LONGEST) value_zerop (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)
{
char *name = &exp->elts[pc+3].string;
int tem = strlen (name);
(*pos) += 2 + (tem + sizeof (union exp_element)) / sizeof (union exp_element);
}
else
evaluate_subexp (expect_type, exp, pos, EVAL_SKIP);
goto nosideret;
}
if (op == OP_SCOPE)
{
char *name = &exp->elts[pc+3].string;
int tem = strlen (name);
struct type *domain = exp->elts[pc+2].type;
(*pos) += 2 + (tem + sizeof (union exp_element)) / sizeof (union exp_element);
arg1 = value_struct_elt_for_address (domain, expect_type, name);
if (arg1)
return arg1;
error ("no field `%s' in structure", name);
}
else
return evaluate_subexp_for_address (exp, pos, noside);
case UNOP_SIZEOF:
if (noside == EVAL_SKIP)
{
evaluate_subexp (0, exp, pos, EVAL_SKIP);
goto nosideret;
}
return evaluate_subexp_for_sizeof (exp, pos);
case UNOP_CAST:
(*pos) += 2;
arg1 = evaluate_subexp (expect_type, exp, pos, noside);
if (noside == EVAL_SKIP)
goto nosideret;
return value_cast (exp->elts[pc + 1].type, 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 (exp->elts[pc + 1].type,
(CORE_ADDR) value_as_long (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_long (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_long (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_long (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_long (builtin_type_char,
(LONGEST) 1));
value_assign (arg1, arg2);
return arg1;
}
case OP_THIS:
(*pos) += 1;
return value_of_this (1);
default:
error ("internal error: I do not know how to evaluate what you gave me");
}
nosideret:
return value_from_long (builtin_type_long, (LONGEST) 1);
}
/* 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
evaluate_subexp_for_address (exp, pos, noside)
register struct expression *exp;
register int *pos;
enum noside noside;
{
enum exp_opcode op;
register int pc;
pc = (*pos);
op = exp->elts[pc].opcode;
switch (op)
{
case UNOP_IND:
(*pos)++;
return evaluate_subexp (0, exp, pos, noside);
case UNOP_MEMVAL:
(*pos) += 3;
return value_cast (lookup_pointer_type (exp->elts[pc + 1].type),
evaluate_subexp (0, exp, pos, noside));
case OP_VAR_VALUE:
(*pos) += 3;
if (noside == EVAL_AVOID_SIDE_EFFECTS)
{
struct type *type =
lookup_pointer_type (SYMBOL_TYPE (exp->elts[pc + 1].symbol));
enum address_class sym_class =
SYMBOL_CLASS (exp->elts[pc + 1].symbol);
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 (exp->elts[pc + 1].symbol, (CORE_ADDR) 0);
default:
if (noside == EVAL_AVOID_SIDE_EFFECTS)
{
value x = evaluate_subexp (0, exp, pos, noside);
if (VALUE_LVAL (x) == lval_memory)
return value_zero (TYPE_POINTER_TYPE (VALUE_TYPE (x)),
not_lval);
else
error ("Attempt to take address of non-lval");
}
return value_addr (evaluate_subexp (0, 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. */
static value
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 val;
pc = (*pos);
op = exp->elts[pc].opcode;
switch (op)
{
case OP_VAR_VALUE:
if (TYPE_CODE (SYMBOL_TYPE (exp->elts[pc + 1].symbol)) == TYPE_CODE_ARRAY)
{
(*pos) += 3;
val = locate_var_value (exp->elts[pc + 1].symbol, (CORE_ADDR) 0);
return value_cast (lookup_pointer_type (TYPE_TARGET_TYPE (SYMBOL_TYPE (exp->elts[pc + 1].symbol))),
val);
}
}
return evaluate_subexp (0, 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
evaluate_subexp_for_sizeof (exp, pos)
register struct expression *exp;
register int *pos;
{
enum exp_opcode op;
register int pc;
value 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 (0, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
return value_from_long (builtin_type_int, (LONGEST)
TYPE_LENGTH (TYPE_TARGET_TYPE (VALUE_TYPE (val))));
case UNOP_MEMVAL:
(*pos) += 3;
return value_from_long (builtin_type_int,
(LONGEST) TYPE_LENGTH (exp->elts[pc + 1].type));
case OP_VAR_VALUE:
(*pos) += 3;
return value_from_long (builtin_type_int,
(LONGEST) TYPE_LENGTH (SYMBOL_TYPE (exp->elts[pc + 1].symbol)));
default:
val = evaluate_subexp (0, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
return value_from_long (builtin_type_int,
(LONGEST) TYPE_LENGTH (VALUE_TYPE (val)));
}
}
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