Create dwarf2/comp-unit.[ch]

This creates the new files dwarf2/comp-unit.[ch], moving
comp_unit_head and helpers to those files.  A couple of functions are
turned into methods, because it was convenient to do so now.

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

	* Makefile.in (COMMON_SFILES): Add dwarf2/comp-unit.c.
	* dwarf2/read.c (struct comp_unit_head): Move to
	dwarf2/comp-unit.h.
	(enum class rcuh_kind): Move to comp-unit.h.
	(get_cu_length, offset_in_cu_p): Now methods on comp_unit_head.
	(read_comp_unit_head, error_check_comp_unit_head)
	(read_and_check_comp_unit_head): Move to comp-unit.c.
	(read_offset, dwarf_unit_type_name): Likewise.
	(create_debug_type_hash_table, read_cutu_die_from_dwo)
	(cutu_reader::cutu_reader, read_call_site_scope)
	(find_partial_die, follow_die_offset): Update.
	* dwarf2/comp-unit.h: New file, from dwarf2read.c.

Change-Id: Id961b9674c0081ed061083c8152c38b27b27388a

1 files changed, 114 insertions, 0 deletions

diff --git a/gdb/dwarf2/comp-unit.h b/gdb/dwarf2/comp-unit.h
new file mode 100644
index 0000000..b4483ac
--- /dev/null
+++ b/gdb/dwarf2/comp-unit.h
@@ -0,0 +1,114 @@
+/* Low-level DWARF 2 reading code
+
+   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_COMP_UNIT_H
+#define GDB_DWARF2_COMP_UNIT_H
+
+#include "gdbtypes.h"
+
+/* The data in a compilation unit header, after target2host
+   translation, looks like this.  */
+struct comp_unit_head
+{
+  unsigned int length;
+  short version;
+  unsigned char addr_size;
+  unsigned char signed_addr_p;
+  sect_offset abbrev_sect_off;
+
+  /* Size of file offsets; either 4 or 8.  */
+  unsigned int offset_size;
+
+  /* Size of the length field; either 4 or 12.  */
+  unsigned int initial_length_size;
+
+  enum dwarf_unit_type unit_type;
+
+  /* Offset to the first byte of this compilation unit header in the
+     .debug_info section, for resolving relative reference dies.  */
+  sect_offset sect_off;
+
+  /* Offset to first die in this cu from the start of the cu.
+     This will be the first byte following the compilation unit header.  */
+  cu_offset first_die_cu_offset;
+
+
+  /* 64-bit signature of this unit. For type units, it denotes the signature of
+     the type (DW_UT_type in DWARF 4, additionally DW_UT_split_type in DWARF 5).
+     Also used in DWARF 5, to denote the dwo id when the unit type is
+     DW_UT_skeleton or DW_UT_split_compile.  */
+  ULONGEST signature;
+
+  /* For types, offset in the type's DIE of the type defined by this TU.  */
+  cu_offset type_cu_offset_in_tu;
+
+  /* Return the total length of the CU described by this header.  */
+  unsigned int get_length () const
+  {
+    return initial_length_size + length;
+  }
+
+  /* Return TRUE if OFF is within this CU.  */
+  bool offset_in_cu_p (sect_offset off) const
+  {
+    sect_offset bottom = sect_off;
+    sect_offset top = sect_off + get_length ();
+    return off >= bottom && off < top;
+  }
+};
+
+/* Expected enum dwarf_unit_type for read_comp_unit_head.  */
+enum class rcuh_kind { COMPILE, TYPE };
+
+/* Read in the comp unit header information from the debug_info at info_ptr.
+   Use rcuh_kind::COMPILE as the default type if not known by the caller.
+   NOTE: This leaves members offset, first_die_offset to be filled in
+   by the caller.  */
+extern const gdb_byte *read_comp_unit_head
+  (struct comp_unit_head *cu_header,
+   const gdb_byte *info_ptr,
+   struct dwarf2_section_info *section,
+   rcuh_kind section_kind);
+
+/* Read in a CU/TU header and perform some basic error checking.
+   The contents of the header are stored in HEADER.
+   The result is a pointer to the start of the first DIE.  */
+extern const gdb_byte *read_and_check_comp_unit_head
+  (struct dwarf2_per_objfile *dwarf2_per_objfile,
+   struct comp_unit_head *header,
+   struct dwarf2_section_info *section,
+   struct dwarf2_section_info *abbrev_section,
+   const gdb_byte *info_ptr,
+   rcuh_kind section_kind);
+
+/* Read an offset from the data stream.  The size of the offset is
+   given by cu_header->offset_size.  */
+
+extern LONGEST read_offset (bfd *abfd, const gdb_byte *buf,
+			    const struct comp_unit_head *cu_header,
+			    unsigned int *bytes_read);
+
+#endif /* GDB_DWARF2_COMP_UNIT_H */