Expose type alignment on gdb.Type

This adds an "alignof" attribute to gdb.Type in the Python API.

2018-04-30  Tom Tromey  <tom@tromey.com>

	* NEWS: Mention Type.align.
	* python/py-type.c (typy_get_alignof): New function.
	(type_object_getset): Add "alignof".

2018-04-30  Tom Tromey  <tom@tromey.com>

	* python.texi (Types In Python): Document Type.align.

2018-04-30  Tom Tromey  <tom@tromey.com>

	* gdb.python/py-type.exp: Check align attribute.
	* gdb.python/py-type.c: New "aligncheck" global.

gdb/ChangeLog

@@ -1,3 +1,9 @@
+2018-04-30  Tom Tromey  <tom@tromey.com>
+
+	* NEWS: Mention Type.align.
+	* python/py-type.c (typy_get_alignof): New function.
+	(type_object_getset): Add "alignof".
+
 2018-04-30  Tom Tromey  <tom@tromey.com>
 
 	PR exp/17095:

gdb/NEWS

@@ -27,6 +27,10 @@ set|show record btrace cpu
   Controls the processor to be used for enabling errata workarounds for
   branch trace decode.
 
+* Python API
+
+  ** Type alignment is now exposed via the "align" attribute of a gdb.Type.
+
 * New targets
 
 RiscV ELF			riscv*-*-elf

gdb/doc/ChangeLog

@@ -1,3 +1,7 @@
+2018-04-30  Tom Tromey  <tom@tromey.com>
+
+	* python.texi (Types In Python): Document Type.align.
+
 2018-04-13  Andreas Arnez  <arnez@linux.vnet.ibm.com>
 
 	* gdb.texinfo (Symbols): Mention the fact that "info

gdb/doc/python.texi

@@ -930,6 +930,13 @@ description of the @code{Type.fields} method for a description of the
 
 An instance of @code{Type} has the following attributes:
 
+@defvar Type.alignof
+The alignment of this type, in bytes.  Type alignment comes from the
+debugging information; if it was not specified, then @value{GDBN} will
+use the relevant ABI to try to determine the alignment.  In some
+cases, even this is not possible, and zero will be returned.
+@end defvar
+
 @defvar Type.code
 The type code for this type.  The type code will be one of the
 @code{TYPE_CODE_} constants defined below.

gdb/python/py-type.c

@@ -730,6 +730,28 @@ typy_get_sizeof (PyObject *self, void *closure)
   return gdb_py_long_from_longest (TYPE_LENGTH (type));
 }
 
+/* Return the alignment of the type represented by SELF, in bytes.  */
+static PyObject *
+typy_get_alignof (PyObject *self, void *closure)
+{
+  struct type *type = ((type_object *) self)->type;
+
+  ULONGEST align = 0;
+  TRY
+    {
+      align = type_align (type);
+    }
+  CATCH (except, RETURN_MASK_ALL)
+    {
+      align = 0;
+    }
+  END_CATCH
+
+  /* Ignore exceptions.  */
+
+  return gdb_py_object_from_ulongest (align);
+}
+
 static struct type *
 typy_lookup_typename (const char *type_name, const struct block *block)
 {
@@ -1410,6 +1432,8 @@ gdbpy_initialize_types (void)
 
 static gdb_PyGetSetDef type_object_getset[] =
 {
+  { "alignof", typy_get_alignof, NULL,
+    "The alignment of this type, in bytes.", NULL },
   { "code", typy_get_code, NULL,
     "The code for this type.", NULL },
   { "name", typy_get_name, NULL,

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2018-04-30  Tom Tromey  <tom@tromey.com>
+
+	* gdb.python/py-type.exp: Check align attribute.
+	* gdb.python/py-type.c: New "aligncheck" global.
+
 2018-04-30  Tom Tromey  <tom@tromey.com>
 
 	PR exp/17095:

gdb/testsuite/gdb.python/py-type.c

@@ -30,6 +30,8 @@ struct SS
 typedef struct s TS;
 TS ts;
 
+int aligncheck;
+
 #ifdef __cplusplus
 struct C
 {

gdb/testsuite/gdb.python/py-type.exp

@@ -278,6 +278,10 @@ if { [build_inferior "${binfile}" "c"] == 0 } {
   gdb_test "python print(gdb.lookup_type('int').optimized_out())" \
       "<optimized out>"
 
+  set sint [get_sizeof int 0]
+  gdb_test "python print(gdb.parse_and_eval('aligncheck').type.alignof)" \
+      $sint
+
   with_test_prefix "lang_c" {
       runto_bp "break to inspect struct and array."
       test_fields "c"