Create dwarf2/attribute.[ch]

This moves the attribute-related code out of dwarf2read.c and into the
new files dwarf2/attribute.[ch].

gdb/ChangeLog
2020-02-08  Tom Tromey  <tom@tromey.com>

	* dwarf2read.c (struct attribute, DW_STRING)
	(DW_STRING_IS_CANONICAL, DW_UNSND, DW_BLOCK, DW_SND, DW_ADDR)
	(DW_SIGNATURE, struct dwarf_block, attr_value_as_address)
	(attr_form_is_block, attr_form_is_section_offset)
	(attr_form_is_constant, attr_form_is_ref): Move.
	* dwarf2/attribute.h: New file.
	* dwarf2/attribute.c: New file, from dwarf2read.c.
	* Makefile.in (COMMON_SFILES): Add dwarf2/attribute.c.

Change-Id: I1ea4c146256a1b9e38b66f1c605d782a14eeded7

1 files changed, 118 insertions, 0 deletions

diff --git a/gdb/dwarf2/attribute.h b/gdb/dwarf2/attribute.h
new file mode 100644
index 0000000..11c6cb9
--- /dev/null
+++ b/gdb/dwarf2/attribute.h
@@ -0,0 +1,118 @@
+/* DWARF attributes
+
+   Copyright (C) 1994-2020 Free Software Foundation, Inc.
+
+   Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
+   Inc.  with support from Florida State University (under contract
+   with the Ada Joint Program Office), and Silicon Graphics, Inc.
+   Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
+   based on Fred Fish's (Cygnus Support) implementation of DWARF 1
+   support.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDB_DWARF2_ATTRIBUTE_H
+#define GDB_DWARF2_ATTRIBUTE_H
+
+#include "dwarf2.h"
+
+/* Blocks are a bunch of untyped bytes.  */
+struct dwarf_block
+{
+  size_t size;
+
+  /* Valid only if SIZE is not zero.  */
+  const gdb_byte *data;
+};
+
+/* Attributes have a name and a value.  */
+struct attribute
+{
+  ENUM_BITFIELD(dwarf_attribute) name : 16;
+  ENUM_BITFIELD(dwarf_form) form : 15;
+
+  /* Has DW_STRING already been updated by dwarf2_canonicalize_name?  This
+     field should be in u.str (existing only for DW_STRING) but it is kept
+     here for better struct attribute alignment.  */
+  unsigned int string_is_canonical : 1;
+
+  union
+    {
+      const char *str;
+      struct dwarf_block *blk;
+      ULONGEST unsnd;
+      LONGEST snd;
+      CORE_ADDR addr;
+      ULONGEST signature;
+    }
+  u;
+};
+
+/* Get at parts of an attribute structure.  */
+
+#define DW_STRING(attr)    ((attr)->u.str)
+#define DW_STRING_IS_CANONICAL(attr) ((attr)->string_is_canonical)
+#define DW_UNSND(attr)     ((attr)->u.unsnd)
+#define DW_BLOCK(attr)     ((attr)->u.blk)
+#define DW_SND(attr)       ((attr)->u.snd)
+#define DW_ADDR(attr)	   ((attr)->u.addr)
+#define DW_SIGNATURE(attr) ((attr)->u.signature)
+
+/* Read the given attribute value as an address, taking the attribute's
+   form into account.  */
+
+extern CORE_ADDR attr_value_as_address (struct attribute *attr);
+
+/* Check if the attribute's form is a DW_FORM_block*
+   if so return true else false.  */
+
+extern int attr_form_is_block (const struct attribute *attr);
+
+/* Return non-zero if ATTR's value is a section offset --- classes
+   lineptr, loclistptr, macptr or rangelistptr --- or zero, otherwise.
+   You may use DW_UNSND (attr) to retrieve such offsets.
+
+   Section 7.5.4, "Attribute Encodings", explains that no attribute
+   may have a value that belongs to more than one of these classes; it
+   would be ambiguous if we did, because we use the same forms for all
+   of them.  */
+
+extern int attr_form_is_section_offset (const struct attribute *attr);
+
+/* Return non-zero if ATTR's value falls in the 'constant' class, or
+   zero otherwise.  When this function returns true, you can apply
+   dwarf2_get_attr_constant_value to it.
+
+   However, note that for some attributes you must check
+   attr_form_is_section_offset before using this test.  DW_FORM_data4
+   and DW_FORM_data8 are members of both the constant class, and of
+   the classes that contain offsets into other debug sections
+   (lineptr, loclistptr, macptr or rangelistptr).  The DWARF spec says
+   that, if an attribute's can be either a constant or one of the
+   section offset classes, DW_FORM_data4 and DW_FORM_data8 should be
+   taken as section offsets, not constants.
+
+   DW_FORM_data16 is not considered as dwarf2_get_attr_constant_value
+   cannot handle that.  */
+
+extern int attr_form_is_constant (const struct attribute *attr);
+
+/* DW_ADDR is always stored already as sect_offset; despite for the forms
+   besides DW_FORM_ref_addr it is stored as cu_offset in the DWARF file.  */
+
+extern int attr_form_is_ref (const struct attribute *attr);
+
+#endif /* GDB_DWARF2_ATTRIBUTE_H */