Address Class documentation.

2 files changed, 136 insertions, 0 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 72544a0..2b0ec6e 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,11 @@
+2002-10-17  Kevin Buettner  <kevinb@redhat.com>
+
+	* gdbint.texinfo (Address Classes): New section.
+	(Target Conditionals): Document ADDRESS_CLASS_NAME_TO_TYPE_FLAGS,
+	ADDRESS_CLASS_NAME_TO_TYPE_FLAGS_P, ADDRESS_CLASS_TYPE_FLAGS,
+	ADDRESS_CLASS_TYPE_FLAGS_P, ADDRESS_CLASS_TYPE_FLAGS_TO_NAME, and
+	ADDRESS_CLASS_TYPE_FLAGS_TO_NAME_P.
+
 2002-10-11  Klee Dienes  <kdienes@apple.com>
 
 	* gdb.texinfo (Registers): Mention vector registers as well as
diff --git a/gdb/doc/gdbint.texinfo b/gdb/doc/gdbint.texinfo
index 87dd5b6..eef2b86 100644
--- a/gdb/doc/gdbint.texinfo
+++ b/gdb/doc/gdbint.texinfo
@@ -2630,6 +2630,91 @@ This function may safely assume that @var{type} is either a pointer or a
 C@t{++} reference type.
 @end deftypefn
 
+@section Address Classes
+@cindex address classes
+@cindex DW_AT_byte_size
+@cindex DW_AT_address_class
+
+Sometimes information about different kinds of addresses is available
+via the debug information.  For example, some programming environments
+define addresses of several different sizes.  If the debug information
+distinguishes these kinds of address classes through either the size
+info (e.g, @code{DW_AT_byte_size} in @w{DWARF 2}) or through an explicit
+address class attribute (e.g, @code{DW_AT_address_class} in @w{DWARF 2}), the
+following macros should be defined in order to disambiguate these
+types within @value{GDBN} as well as provide the added information to
+a @value{GDBN} user when printing type expressions.
+
+@deftypefn {Target Macro} int ADDRESS_CLASS_TYPE_FLAGS (int @var{byte_size}, int @var{dwarf2_addr_class})
+Returns the type flags needed to construct a pointer type whose size
+is @var{byte_size} and whose address class is @var{dwarf2_addr_class}.
+This function is normally called from within a symbol reader.  See
+@file{dwarf2read.c}.
+@end deftypefn
+
+@deftypefn {Target Macro} char *ADDRESS_CLASS_TYPE_FLAGS_TO_NAME (int @var{type_flags})
+Given the type flags representing an address class qualifier, return
+its name.
+@end deftypefn
+@deftypefn {Target Macro} int ADDRESS_CLASS_NAME_to_TYPE_FLAGS (int @var{name}, int *var{type_flags_ptr})
+Given an address qualifier name, set the @code{int} refererenced by @var{type_flags_ptr} to the type flags
+for that address class qualifier.
+@end deftypefn
+
+Since the need for address classes is rather rare, none of
+the address class macros defined by default.  Predicate
+macros are provided to detect when they are defined.
+
+Consider a hypothetical architecture in which addresses are normally
+32-bits wide, but 16-bit addresses are also supported.  Furthermore,
+suppose that the @w{DWARF 2} information for this architecture simply
+uses a @code{DW_AT_byte_size} value of 2 to indicate the use of one
+of these "short" pointers.  The following functions could be defined
+to implement the address class macros:
+
+@smallexample
+somearch_address_class_type_flags (int byte_size,
+                                   int dwarf2_addr_class)
+{
+  if (byte_size == 2)
+    return TYPE_FLAG_ADDRESS_CLASS_1;
+  else
+    return 0;
+}
+
+static char *
+somearch_address_class_type_flags_to_name (int type_flags)
+{
+  if (type_flags & TYPE_FLAG_ADDRESS_CLASS_1)
+    return "short";
+  else
+    return NULL;
+}
+
+int
+somearch_address_class_name_to_type_flags (char *name,
+                                           int *type_flags_ptr)
+{
+  if (strcmp (name, "short") == 0)
+    {
+      *type_flags_ptr = TYPE_FLAG_ADDRESS_CLASS_1;
+      return 1;
+    }
+  else
+    return 0;
+}
+@end smallexample
+
+The qualifier @code{@@short} is used in @value{GDBN}'s type expressions
+to indicate the presence of one of these "short" pointers.  E.g, if
+the debug information indicates that @code{short_ptr_var} is one of these
+short pointers, @value{GDBN} might show the following behavior:
+
+@smallexample
+(gdb) ptype short_ptr_var
+type = int * @@short
+@end smallexample
+
 
 @section Raw and Virtual Register Representations
 @cindex raw register representation
@@ -2857,6 +2942,49 @@ boundaries, the processor masks out these bits to generate the actual
 address of the instruction.  ADDR_BITS_REMOVE should filter out these
 bits with an expression such as @code{((addr) & ~3)}.
 
+@item ADDRESS_CLASS_NAME_TO_TYPE_FLAGS (@var{name}, @var{type_flags_ptr})
+@findex ADDRESS_CLASS_NAME_TO_TYPE_FLAGS
+If @var{name} is a valid address class qualifier name, set the @code{int}
+referenced by @var{type_flags_ptr} to the mask representing the qualifier
+and return 1.  If @var{name} is not a valid address class qualifier name,
+return 0.
+
+The value for @var{type_flags_ptr} should be one of
+@code{TYPE_FLAG_ADDRESS_CLASS_1}, @code{TYPE_FLAG_ADDRESS_CLASS_2}, or
+possibly some combination of these values or'd together.
+@xref{Target Architecture Definition, , Address Classes}.
+
+@item ADDRESS_CLASS_NAME_TO_TYPE_FLAGS_P ()
+@findex ADDRESS_CLASS_NAME_TO_TYPE_FLAGS_P
+Predicate which indicates whether @code{ADDRESS_CLASS_NAME_TO_TYPE_FLAGS}
+has been defined.
+
+@item ADDRESS_CLASS_TYPE_FLAGS (@var{byte_size}, @var{dwarf2_addr_class})
+@findex ADDRESS_CLASS_TYPE_FLAGS (@var{byte_size}, @var{dwarf2_addr_class})
+Given a pointers byte size (as described by the debug information) and
+the possible @code{DW_AT_address_class} value, return the type flags
+used by @value{GDBN} to represent this address class.  The value
+returned should be one of @code{TYPE_FLAG_ADDRESS_CLASS_1},
+@code{TYPE_FLAG_ADDRESS_CLASS_2}, or possibly some combination of these
+values or'd together.
+@xref{Target Architecture Definition, , Address Classes}.
+
+@item ADDRESS_CLASS_TYPE_FLAGS_P ()
+@findex ADDRESS_CLASS_TYPE_FLAGS_P
+Predicate which indicates whether @code{ADDRESS_CLASS_TYPE_FLAGS} has
+been defined.
+
+@item ADDRESS_CLASS_TYPE_FLAGS_TO_NAME (@var{type_flags})
+@findex ADDRESS_CLASS_TYPE_FLAGS_TO_NAME
+Return the name of the address class qualifier associated with the type
+flags given by @var{type_flags}.
+
+@item ADDRESS_CLASS_TYPE_FLAGS_TO_NAME_P ()
+@findex ADDRESS_CLASS_TYPE_FLAGS_TO_NAME_P
+Predicate which indicates whether @code{ADDRESS_CLASS_TYPE_FLAGS_TO_NAME} has
+been defined.
+@xref{Target Architecture Definition, , Address Classes}.
+
 @item ADDRESS_TO_POINTER (@var{type}, @var{buf}, @var{addr})
 @findex ADDRESS_TO_POINTER
 Store in @var{buf} a pointer of type @var{type} representing the address