[rfc][08/37] Eliminate builtin_type_ macros: Make pointer arithmetic explicit

[uweigand at de dot ibm dot com]

Hello,

this patch removes the functions value_add and value_sub which handle
both integer and pointer arithmetic, and replaces them by functions
value_ptradd, value_ptrsub, and value_ptrdiff that solely take care
of C-style pointer arithmetic.  (For integer arithmetic, value_binop
can be used.)

This moves the type to be used for pointer difference operations up
eval.c (this should at some point be replaces by a per-gdbarch 
"ptrdiff_t" type).  It also makes the subsequent patches to remove
current_gdbarch references from value_binop simpler.

Bye,
Ulrich


ChangeLog:

	* value.h (value_add, value_sub): Remove.
	(value_ptradd, value_ptrsub, value_ptrdiff): Add prototypes.
	* valarith.c (value_add, value_sub): Remove.
	(value_ptradd, value_ptrsub, value_ptrdiff): New functions.
	(find_size_for_pointer_math): Add assertion.  Update comment.
	(value_binop): Update comment.

	* eval.c (ptrmath_type_p): New function.
	(evaluate_subexp_standard): Replace value_add and value_sub
	by value_ptradd, value_ptrsub, value_ptrdiff or value_binop.
	Use builtin_type_uint8 instead of builtin_type_char to hold
	the increment for BINOP_{PRE,POST}{IN,DE}CREMENT operations.
 	* valarith.c (value_subscript): Replace value_add by
	value_ptradd.  Replace value_sub by value_binop.
	* ada-lang.c (ada_value_ptr_subscript): Likewise.
	(ada_tag_name_2): Replace value_add by value_ptradd.
	(ada_evaluate_subexp): Replace value_add and value_sub by
	value_binop.
	* m2-lang.c (evaluate_subexp_modula2): Replace value_add
	by value_ptradd.
	* gnu-v2-abi.c (gnuv2_virtual_fn_field): Likewise.
	* gnu-v3-abi.c (gnuv3_method_ptr_to_value): Likewise.


Index: gdb-head/gdb/ada-lang.c
===================================================================
--- gdb-head.orig/gdb/ada-lang.c
+++ gdb-head/gdb/ada-lang.c
@@ -2371,8 +2371,10 @@ ada_value_ptr_subscript (struct value *a
       get_discrete_bounds (TYPE_INDEX_TYPE (type), &lwb, &upb);
       idx = value_pos_atr (ind[k]);
       if (lwb != 0)
-        idx = value_sub (idx, value_from_longest (builtin_type_int, lwb));
-      arr = value_add (arr, idx);
+	idx = value_binop (idx, value_from_longest (value_type (idx), lwb),
+			   BINOP_SUB);
+
+      arr = value_ptradd (arr, idx);
       type = TYPE_TARGET_TYPE (type);
     }
 
@@ -5798,7 +5800,8 @@ ada_tag_name_2 (struct tag_args *args)
   valp = value_cast (info_type, args->tag);
   if (valp == NULL)
     return 0;
-  val = value_ind (value_add (valp, value_from_longest (builtin_type_int, -1)));
+  val = value_ind (value_ptradd (valp,
+				 value_from_longest (builtin_type_int8, -1)));
   if (val == NULL)
     return 0;
   val = ada_value_struct_elt (val, "expanded_name", 1);
@@ -8518,7 +8521,7 @@ ada_evaluate_subexp (struct type *expect
       type = value_type (arg1);
       while (TYPE_CODE (type) == TYPE_CODE_REF)
         type = TYPE_TARGET_TYPE (type);
-      return value_cast (type, value_add (arg1, arg2));
+      return value_cast (type, value_binop (arg1, arg2, BINOP_ADD));
 
     case BINOP_SUB:
       arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
@@ -8535,7 +8538,7 @@ ada_evaluate_subexp (struct type *expect
       type = value_type (arg1);
       while (TYPE_CODE (type) == TYPE_CODE_REF)
         type = TYPE_TARGET_TYPE (type);
-      return value_cast (type, value_sub (arg1, arg2));
+      return value_cast (type, value_binop (arg1, arg2, BINOP_SUB));
 
     case BINOP_MUL:
     case BINOP_DIV:
Index: gdb-head/gdb/eval.c
===================================================================
--- gdb-head.orig/gdb/eval.c
+++ gdb-head/gdb/eval.c
@@ -439,6 +439,27 @@ value_f90_subarray (struct value *array,
   return value_slice (array, low_bound, high_bound - low_bound + 1);
 }
 
+static int
+ptrmath_type_p (struct type *type)
+{
+  type = check_typedef (type);
+  if (TYPE_CODE (type) == TYPE_CODE_REF)
+    type = TYPE_TARGET_TYPE (type);
+
+  switch (TYPE_CODE (type))
+    {
+    case TYPE_CODE_PTR:
+    case TYPE_CODE_FUNC:
+      return 1;
+
+    case TYPE_CODE_ARRAY:
+      return current_language->c_style_arrays;
+
+    default:
+      return 0;
+    }
+}
+
 struct value *
 evaluate_subexp_standard (struct type *expect_type,
 			  struct expression *exp, int *pos,
@@ -1506,10 +1527,10 @@ evaluate_subexp_standard (struct type *e
       op = exp->elts[pc + 1].opcode;
       if (binop_user_defined_p (op, arg1, arg2))
 	return value_x_binop (arg1, arg2, BINOP_ASSIGN_MODIFY, op, noside);
-      else if (op == BINOP_ADD)
-	arg2 = value_add (arg1, arg2);
-      else if (op == BINOP_SUB)
-	arg2 = value_sub (arg1, arg2);
+      else if (op == BINOP_ADD && ptrmath_type_p (value_type (arg1)))
+	arg2 = value_ptradd (arg1, arg2);
+      else if (op == BINOP_SUB && ptrmath_type_p (value_type (arg1)))
+	arg2 = value_ptrsub (arg1, arg2);
       else
 	arg2 = value_binop (arg1, arg2, op);
       return value_assign (arg1, arg2);
@@ -1521,8 +1542,12 @@ evaluate_subexp_standard (struct type *e
 	goto nosideret;
       if (binop_user_defined_p (op, arg1, arg2))
 	return value_x_binop (arg1, arg2, op, OP_NULL, noside);
+      else if (ptrmath_type_p (value_type (arg1)))
+	return value_ptradd (arg1, arg2);
+      else if (ptrmath_type_p (value_type (arg2)))
+	return value_ptradd (arg2, arg1);
       else
-	return value_add (arg1, arg2);
+	return value_binop (arg1, arg2, BINOP_ADD);
 
     case BINOP_SUB:
       arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
@@ -1531,8 +1556,19 @@ evaluate_subexp_standard (struct type *e
 	goto nosideret;
       if (binop_user_defined_p (op, arg1, arg2))
 	return value_x_binop (arg1, arg2, op, OP_NULL, noside);
+      else if (ptrmath_type_p (value_type (arg1))
+	       && ptrmath_type_p (value_type (arg2)))
+	{
+	  /* FIXME -- should be ptrdiff_t */
+	  type = builtin_type (exp->gdbarch)->builtin_long;
+	  return value_from_longest (type, value_ptrdiff (arg1, arg2));
+	}
+      else if (ptrmath_type_p (value_type (arg1)))
+	return value_ptrsub (arg1, arg2);
+      else if (ptrmath_type_p (value_type (arg2)))
+	return value_ptrsub (arg2, arg1);
       else
-	return value_sub (arg1, arg2);
+	return value_binop (arg1, arg2, BINOP_SUB);
 
     case BINOP_EXP:
     case BINOP_MUL:
@@ -2091,8 +2127,12 @@ evaluate_subexp_standard (struct type *e
 	}
       else
 	{
-	  arg2 = value_add (arg1, value_from_longest (builtin_type_char,
-						      (LONGEST) 1));
+	  arg2 = value_from_longest (builtin_type_uint8, (LONGEST) 1);
+	  if (ptrmath_type_p (value_type (arg1)))
+	    arg2 = value_ptradd (arg1, arg2);
+	  else
+	    arg2 = value_binop (arg1, arg2, BINOP_ADD);
+
 	  return value_assign (arg1, arg2);
 	}
 
@@ -2106,8 +2146,12 @@ evaluate_subexp_standard (struct type *e
 	}
       else
 	{
-	  arg2 = value_sub (arg1, value_from_longest (builtin_type_char,
-						      (LONGEST) 1));
+	  arg2 = value_from_longest (builtin_type_uint8, (LONGEST) 1);
+	  if (ptrmath_type_p (value_type (arg1)))
+	    arg2 = value_ptrsub (arg1, arg2);
+	  else
+	    arg2 = value_binop (arg1, arg2, BINOP_SUB);
+
 	  return value_assign (arg1, arg2);
 	}
 
@@ -2121,8 +2165,12 @@ evaluate_subexp_standard (struct type *e
 	}
       else
 	{
-	  arg2 = value_add (arg1, value_from_longest (builtin_type_char,
-						      (LONGEST) 1));
+	  arg2 = value_from_longest (builtin_type_uint8, (LONGEST) 1);
+	  if (ptrmath_type_p (value_type (arg1)))
+	    arg2 = value_ptradd (arg1, arg2);
+	  else
+	    arg2 = value_binop (arg1, arg2, BINOP_ADD);
+
 	  value_assign (arg1, arg2);
 	  return arg1;
 	}
@@ -2137,8 +2185,12 @@ evaluate_subexp_standard (struct type *e
 	}
       else
 	{
-	  arg2 = value_sub (arg1, value_from_longest (builtin_type_char,
-						      (LONGEST) 1));
+	  arg2 = value_from_longest (builtin_type_uint8, (LONGEST) 1);
+	  if (ptrmath_type_p (value_type (arg1)))
+	    arg2 = value_ptrsub (arg1, arg2);
+	  else
+	    arg2 = value_binop (arg1, arg2, BINOP_SUB);
+
 	  value_assign (arg1, arg2);
 	  return arg1;
 	}
Index: gdb-head/gdb/gnu-v2-abi.c
===================================================================
--- gdb-head.orig/gdb/gnu-v2-abi.c
+++ gdb-head/gdb/gnu-v2-abi.c
@@ -151,7 +151,7 @@ gnuv2_virtual_fn_field (struct value **a
   else
     {
       /* Handle the case where the vtbl field points directly to a structure. */
-      vtbl = value_add (vtbl, vi);
+      vtbl = value_ptradd (vtbl, vi);
       entry = value_ind (vtbl);
     }
 
Index: gdb-head/gdb/gnu-v3-abi.c
===================================================================
--- gdb-head.orig/gdb/gnu-v3-abi.c
+++ gdb-head/gdb/gnu-v3-abi.c
@@ -662,7 +662,7 @@ gnuv3_method_ptr_to_value (struct value 
      instance.  */
   *this_p = value_cast (builtin_type_void_data_ptr, *this_p);
   adjval = value_from_longest (builtin_type_long, adjustment);
-  *this_p = value_add (*this_p, adjval);
+  *this_p = value_ptradd (*this_p, adjval);
   *this_p = value_cast (final_type, *this_p);
 
   if (vbit)
Index: gdb-head/gdb/m2-lang.c
===================================================================
--- gdb-head.orig/gdb/m2-lang.c
+++ gdb-head/gdb/m2-lang.c
@@ -251,7 +251,7 @@ evaluate_subexp_modula2 (struct type *ex
 	    arg1 = value_cast (type, arg1);
 
 	  type = check_typedef (value_type (arg1));
-	  return value_ind (value_add (arg1, arg2));
+	  return value_ind (value_ptradd (arg1, arg2));
 	}
       else
 	if (TYPE_CODE (type) != TYPE_CODE_ARRAY)
Index: gdb-head/gdb/valarith.c
===================================================================
--- gdb-head.orig/gdb/valarith.c
+++ gdb-head/gdb/valarith.c
@@ -50,7 +50,7 @@ void _initialize_valarith (void);
    If the pointer type is void *, then return 1.
    If the target type is incomplete, then error out.
    This isn't a general purpose function, but just a 
-   helper for value_sub & value_add.
+   helper for value_ptrsub & value_ptradd.
 */
 
 static LONGEST
@@ -59,6 +59,7 @@ find_size_for_pointer_math (struct type 
   LONGEST sz = -1;
   struct type *ptr_target;
 
+  gdb_assert (TYPE_CODE (ptr_type) == TYPE_CODE_PTR);
   ptr_target = check_typedef (TYPE_TARGET_TYPE (ptr_type));
 
   sz = TYPE_LENGTH (ptr_target);
@@ -84,90 +85,73 @@ find_size_for_pointer_math (struct type 
   return sz;
 }
 
+/* Given a pointer ARG1 and an integral value ARG2, return the
+   result of C-style pointer arithmetic ARG1 + ARG2.  */
+
 struct value *
-value_add (struct value *arg1, struct value *arg2)
+value_ptradd (struct value *arg1, struct value *arg2)
 {
-  struct value *valint;
-  struct value *valptr;
+  struct type *valptrtype;
   LONGEST sz;
-  struct type *type1, *type2, *valptrtype;
 
   arg1 = coerce_array (arg1);
-  arg2 = coerce_array (arg2);
-  type1 = check_typedef (value_type (arg1));
-  type2 = check_typedef (value_type (arg2));
+  valptrtype = check_typedef (value_type (arg1));
+  sz = find_size_for_pointer_math (valptrtype);
 
-  if ((TYPE_CODE (type1) == TYPE_CODE_PTR
-       || TYPE_CODE (type2) == TYPE_CODE_PTR)
-      &&
-      (is_integral_type (type1) || is_integral_type (type2)))
-    /* Exactly one argument is a pointer, and one is an integer.  */
-    {
-      struct value *retval;
-
-      if (TYPE_CODE (type1) == TYPE_CODE_PTR)
-	{
-	  valptr = arg1;
-	  valint = arg2;
-	  valptrtype = type1;
-	}
-      else
-	{
-	  valptr = arg2;
-	  valint = arg1;
-	  valptrtype = type2;
-	}
+  if (!is_integral_type (value_type (arg2)))
+    error (_("Argument to arithmetic operation not a number or boolean."));
+
+  return value_from_pointer (valptrtype,
+			     value_as_address (arg1)
+			       + (sz * value_as_long (arg2)));
+}
 
-      sz = find_size_for_pointer_math (valptrtype);
+/* Given a pointer ARG1 and an integral value ARG2, return the
+   result of C-style pointer arithmetic ARG1 - ARG2.  */
 
-      retval = value_from_pointer (valptrtype,
-				   value_as_address (valptr)
-				   + (sz * value_as_long (valint)));
-      return retval;
-    }
+struct value *
+value_ptrsub (struct value *arg1, struct value *arg2)
+{
+  struct type *valptrtype;
+  LONGEST sz;
 
-  return value_binop (arg1, arg2, BINOP_ADD);
+  arg1 = coerce_array (arg1);
+  valptrtype = check_typedef (value_type (arg1));
+  sz = find_size_for_pointer_math (valptrtype);
+
+  if (!is_integral_type (value_type (arg2)))
+    error (_("Argument to arithmetic operation not a number or boolean."));
+
+  return value_from_pointer (valptrtype,
+			     value_as_address (arg1)
+			       - (sz * value_as_long (arg2)));
 }
 
-struct value *
-value_sub (struct value *arg1, struct value *arg2)
+/* Given two compatible pointer values ARG1 and ARG2, return the
+   result of C-style pointer arithmetic ARG1 - ARG2.  */
+
+LONGEST
+value_ptrdiff (struct value *arg1, struct value *arg2)
 {
   struct type *type1, *type2;
+  LONGEST sz;
+
   arg1 = coerce_array (arg1);
   arg2 = coerce_array (arg2);
   type1 = check_typedef (value_type (arg1));
   type2 = check_typedef (value_type (arg2));
 
-  if (TYPE_CODE (type1) == TYPE_CODE_PTR)
-    {
-      if (is_integral_type (type2))
-	{
-	  /* pointer - integer.  */
-	  LONGEST sz = find_size_for_pointer_math (type1);
+  gdb_assert (TYPE_CODE (type1) == TYPE_CODE_PTR);
+  gdb_assert (TYPE_CODE (type2) == TYPE_CODE_PTR);
 
-	  return value_from_pointer (type1,
-				     (value_as_address (arg1)
-				      - (sz * value_as_long (arg2))));
-	}
-      else if (TYPE_CODE (type2) == TYPE_CODE_PTR
-	       && TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type1)))
-	       == TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type2))))
-	{
-	  /* pointer to <type x> - pointer to <type x>.  */
-	  LONGEST sz = TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type1)));
-	  return value_from_longest
-	    (builtin_type_long,	/* FIXME -- should be ptrdiff_t */
-	     (value_as_long (arg1) - value_as_long (arg2)) / sz);
-	}
-      else
-	{
-	  error (_("\
+  if (TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type1)))
+      != TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type2))))
+    error (_("\
 First argument of `-' is a pointer and second argument is neither\n\
 an integer nor a pointer of the same type."));
-	}
-    }
 
-  return value_binop (arg1, arg2, BINOP_SUB);
+  sz = TYPE_LENGTH (check_typedef (TYPE_TARGET_TYPE (type1)));
+  return (value_as_long (arg1) - value_as_long (arg2)) / sz;
 }
 
 /* Return the value of ARRAY[IDX].
@@ -211,15 +195,15 @@ value_subscript (struct value *array, st
 
       if (lowerbound != 0)
 	{
-	  bound = value_from_longest (builtin_type_int, (LONGEST) lowerbound);
-	  idx = value_sub (idx, bound);
+	  bound = value_from_longest (value_type (idx), (LONGEST) lowerbound);
+	  idx = value_binop (idx, bound, BINOP_SUB);
 	}
 
       array = value_coerce_array (array);
     }
 
   if (c_style)
-    return value_ind (value_add (array, idx));
+    return value_ind (value_ptradd (array, idx));
   else
     error (_("not an array or string"));
 }
@@ -1171,7 +1155,7 @@ value_args_as_decimal (struct value *arg
    representations as integers or floats.  This includes booleans,
    characters, integers, or floats.
    Does not support addition and subtraction on pointers;
-   use value_add or value_sub if you want to handle those possibilities.  */
+   use value_ptradd, value_ptrsub or value_ptrdiff for those operations.  */
 
 struct value *
 value_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
Index: gdb-head/gdb/value.h
===================================================================
--- gdb-head.orig/gdb/value.h
+++ gdb-head/gdb/value.h
@@ -331,9 +331,11 @@ extern struct value *value_concat (struc
 extern struct value *value_binop (struct value *arg1, struct value *arg2,
 				  enum exp_opcode op);
 
-extern struct value *value_add (struct value *arg1, struct value *arg2);
+extern struct value *value_ptradd (struct value *arg1, struct value *arg2);
 
-extern struct value *value_sub (struct value *arg1, struct value *arg2);
+extern struct value *value_ptrsub (struct value *arg1, struct value *arg2);
+
+extern LONGEST value_ptrdiff (struct value *arg1, struct value *arg2);
 
 extern int value_must_coerce_to_target (struct value *arg1);
 

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com