* 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.