* gdbarch.sh (POINTER_TO_ADDRESS, ADDRESS_TO_POINTER): Two new

* gdbarch.sh (POINTER_TO_ADDRESS, ADDRESS_TO_POINTER): Two new
functions which architectures can redefine, defaulting to
generic_pointer_to_address and generic_address_to_pointer.
* findvar.c (extract_typed_address, store_typed_address,
generic_pointer_to_address, generic_address_to_pointer): New
functions.
(POINTER_TO_ADDRESS, ADDRESS_TO_POINTER): Provide default
definitions.
(extract_address, store_address): Doc fixes.
* values.c (value_as_pointer): Doc fix.
(value_from_pointer): New function.
* defs.h (extract_typed_address, store_typed_address): New
declarations.
* inferior.h (generic_address_to_pointer,
generic_pointer_to_address): New declarations.
* value.h (value_from_pointer): New declaration.

* ax-gdb.c (const_var_ref): Use value_from_pointer, not
value_from_longest.
* blockframe.c (generic_push_dummy_frame): Use read_pc and
read_sp, not read_register.
* c-valprint.c (c_val_print): Use extract_typed_address instead of
extract_address to extract vtable entries and references.
* cp-valprint.c (cp_print_value_fields): Use value_from_pointer
instead of value_from_longest to extract the vtable's address.
* eval.c (evaluate_subexp_standard): Use value_from_pointer
instead of value_from_longest to compute `this', and for doing
pointer-to-member dereferencing.
* findvar.c (read_register): Use extract_unsigned_integer, not
extract_address.
(read_var_value): Use store_typed_address instead of store_address
for building label values.
(locate_var_value): Use value_from_pointer instead of
value_from_longest.
* hppa-tdep.c (find_stub_with_shl_get): Use value_from_pointer,
instead of value_from_longest, to build arguments to __d_shl_get.
* printcmd.c (set_next_address): Use value_from_pointer, not
value_from_longest.
(x_command): Use value_from_pointer, not value_from_longest.
* tracepoint.c (set_traceframe_context): Use value_from_pointer,
not value_from_longest.
* valarith.c (value_add, value_sub): Use value_from_pointer, not
value_from_longest.
* valops.c (find_function_in_inferior, value_coerce_array,
value_coerce_function, value_addr, hand_function_call): Same.
* value.h (COERCE_REF): Use unpack_pointer, not unpack_long.
* values.c (unpack_long): Use extract_typed_address to produce
addresses from pointers and references, not extract_address.
(value_from_longest): Use store_typed_address instead of
store_address to produce pointer and reference values.