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

5 files changed, 378 insertions, 293 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 519225f..c38bcae 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,20 @@
 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.
+
+2020-02-08  Tom Tromey  <tom@tromey.com>
+
 	* dwarf2/read.c (read_offset_1): Move to leb.c.
 	(read_abbrev_offset, read_offset, dwarf_decode_line_header)
 	(dwarf_decode_macro_bytes): Update.
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index b4bd9d4..8870728 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -996,6 +996,7 @@ COMMON_SFILES = \
 	dummy-frame.c \
 	dwarf2/abbrev.c \
 	dwarf2/attribute.c \
+	dwarf2/comp-unit.c \
 	dwarf2/expr.c \
 	dwarf2/frame-tailcall.c \
 	dwarf2/frame.c \
diff --git a/gdb/dwarf2/comp-unit.c b/gdb/dwarf2/comp-unit.c
new file mode 100644
index 0000000..03e804b
--- /dev/null
+++ b/gdb/dwarf2/comp-unit.c
@@ -0,0 +1,237 @@
+/* DWARF 2 debugging format support for GDB.
+
+   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/>.  */
+
+#include "defs.h"
+#include "dwarf2/comp-unit.h"
+#include "dwarf2/leb.h"
+#include "dwarf2/read.h"
+#include "dwarf2/section.h"
+
+/* Convert a unit type to corresponding DW_UT name.  */
+
+static const char *
+dwarf_unit_type_name (int unit_type)
+{
+  switch (unit_type)
+    {
+      case 0x01:
+	return "DW_UT_compile (0x01)";
+      case 0x02:
+	return "DW_UT_type (0x02)";
+      case 0x03:
+	return "DW_UT_partial (0x03)";
+      case 0x04:
+	return "DW_UT_skeleton (0x04)";
+      case 0x05:
+	return "DW_UT_split_compile (0x05)";
+      case 0x06:
+	return "DW_UT_split_type (0x06)";
+      case 0x80:
+	return "DW_UT_lo_user (0x80)";
+      case 0xff:
+	return "DW_UT_hi_user (0xff)";
+      default:
+	return nullptr;
+    }
+}
+
+/* See comp-unit.h.  */
+
+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)
+{
+  int signed_addr;
+  unsigned int bytes_read;
+  const char *filename = section->get_file_name ();
+  bfd *abfd = section->get_bfd_owner ();
+
+  cu_header->length = read_initial_length (abfd, info_ptr, &bytes_read);
+  cu_header->initial_length_size = bytes_read;
+  cu_header->offset_size = (bytes_read == 4) ? 4 : 8;
+  info_ptr += bytes_read;
+  cu_header->version = read_2_bytes (abfd, info_ptr);
+  if (cu_header->version < 2 || cu_header->version > 5)
+    error (_("Dwarf Error: wrong version in compilation unit header "
+	   "(is %d, should be 2, 3, 4 or 5) [in module %s]"),
+	   cu_header->version, filename);
+  info_ptr += 2;
+  if (cu_header->version < 5)
+    switch (section_kind)
+      {
+      case rcuh_kind::COMPILE:
+	cu_header->unit_type = DW_UT_compile;
+	break;
+      case rcuh_kind::TYPE:
+	cu_header->unit_type = DW_UT_type;
+	break;
+      default:
+	internal_error (__FILE__, __LINE__,
+			_("read_comp_unit_head: invalid section_kind"));
+      }
+  else
+    {
+      cu_header->unit_type = static_cast<enum dwarf_unit_type>
+						 (read_1_byte (abfd, info_ptr));
+      info_ptr += 1;
+      switch (cu_header->unit_type)
+	{
+	case DW_UT_compile:
+	case DW_UT_partial:
+	case DW_UT_skeleton:
+	case DW_UT_split_compile:
+	  if (section_kind != rcuh_kind::COMPILE)
+	    error (_("Dwarf Error: wrong unit_type in compilation unit header "
+		   "(is %s, should be %s) [in module %s]"),
+		   dwarf_unit_type_name (cu_header->unit_type),
+		   dwarf_unit_type_name (DW_UT_type), filename);
+	  break;
+	case DW_UT_type:
+	case DW_UT_split_type:
+	  section_kind = rcuh_kind::TYPE;
+	  break;
+	default:
+	  error (_("Dwarf Error: wrong unit_type in compilation unit header "
+		 "(is %#04x, should be one of: %s, %s, %s, %s or %s) "
+		 "[in module %s]"), cu_header->unit_type,
+		 dwarf_unit_type_name (DW_UT_compile),
+		 dwarf_unit_type_name (DW_UT_skeleton),
+		 dwarf_unit_type_name (DW_UT_split_compile),
+		 dwarf_unit_type_name (DW_UT_type),
+		 dwarf_unit_type_name (DW_UT_split_type), filename);
+	}
+
+      cu_header->addr_size = read_1_byte (abfd, info_ptr);
+      info_ptr += 1;
+    }
+  cu_header->abbrev_sect_off = (sect_offset) read_offset (abfd, info_ptr,
+							  cu_header,
+							  &bytes_read);
+  info_ptr += bytes_read;
+  if (cu_header->version < 5)
+    {
+      cu_header->addr_size = read_1_byte (abfd, info_ptr);
+      info_ptr += 1;
+    }
+  signed_addr = bfd_get_sign_extend_vma (abfd);
+  if (signed_addr < 0)
+    internal_error (__FILE__, __LINE__,
+		    _("read_comp_unit_head: dwarf from non elf file"));
+  cu_header->signed_addr_p = signed_addr;
+
+  bool header_has_signature = section_kind == rcuh_kind::TYPE
+    || cu_header->unit_type == DW_UT_skeleton
+    || cu_header->unit_type == DW_UT_split_compile;
+
+  if (header_has_signature)
+    {
+      cu_header->signature = read_8_bytes (abfd, info_ptr);
+      info_ptr += 8;
+    }
+
+  if (section_kind == rcuh_kind::TYPE)
+    {
+      LONGEST type_offset;
+      type_offset = read_offset (abfd, info_ptr, cu_header, &bytes_read);
+      info_ptr += bytes_read;
+      cu_header->type_cu_offset_in_tu = (cu_offset) type_offset;
+      if (to_underlying (cu_header->type_cu_offset_in_tu) != type_offset)
+	error (_("Dwarf Error: Too big type_offset in compilation unit "
+	       "header (is %s) [in module %s]"), plongest (type_offset),
+	       filename);
+    }
+
+  return info_ptr;
+}
+
+/* Subroutine of read_and_check_comp_unit_head and
+   read_and_check_type_unit_head to simplify them.
+   Perform various error checking on the header.  */
+
+static void
+error_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 char *filename = section->get_file_name ();
+
+  if (to_underlying (header->abbrev_sect_off)
+      >= abbrev_section->get_size (dwarf2_per_objfile->objfile))
+    error (_("Dwarf Error: bad offset (%s) in compilation unit header "
+	   "(offset %s + 6) [in module %s]"),
+	   sect_offset_str (header->abbrev_sect_off),
+	   sect_offset_str (header->sect_off),
+	   filename);
+
+  /* Cast to ULONGEST to use 64-bit arithmetic when possible to
+     avoid potential 32-bit overflow.  */
+  if (((ULONGEST) header->sect_off + header->get_length ())
+      > section->size)
+    error (_("Dwarf Error: bad length (0x%x) in compilation unit header "
+	   "(offset %s + 0) [in module %s]"),
+	   header->length, sect_offset_str (header->sect_off),
+	   filename);
+}
+
+/* See comp-unit.h.  */
+
+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)
+{
+  const gdb_byte *beg_of_comp_unit = info_ptr;
+
+  header->sect_off = (sect_offset) (beg_of_comp_unit - section->buffer);
+
+  info_ptr = read_comp_unit_head (header, info_ptr, section, section_kind);
+
+  header->first_die_cu_offset = (cu_offset) (info_ptr - beg_of_comp_unit);
+
+  error_check_comp_unit_head (dwarf2_per_objfile, header, section,
+			      abbrev_section);
+
+  return info_ptr;
+}
+
+/* See comp-unit.h.  */
+
+LONGEST
+read_offset (bfd *abfd, const gdb_byte *buf,
+	     const struct comp_unit_head *cu_header,
+             unsigned int *bytes_read)
+{
+  LONGEST offset = read_offset (abfd, buf, cu_header->offset_size);
+
+  *bytes_read = cu_header->offset_size;
+  return offset;
+}
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 */
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index f291d8f..ef72214 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -32,6 +32,7 @@
 #include "dwarf2/read.h"
 #include "dwarf2/abbrev.h"
 #include "dwarf2/attribute.h"
+#include "dwarf2/comp-unit.h"
 #include "dwarf2/index-cache.h"
 #include "dwarf2/index-common.h"
 #include "dwarf2/leb.h"
@@ -340,43 +341,6 @@ dwop_section_names =
 
 /* local data types */
 
-/* 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;
-};
-
 /* Type used for delaying computation of method physnames.
    See comments for compute_delayed_physnames.  */
 struct delayed_method_info
@@ -1281,10 +1245,6 @@ static LONGEST read_checked_initial_length_and_offset
   (bfd *, const gdb_byte *, const struct comp_unit_head *,
    unsigned int *, unsigned int *);
 
-static LONGEST read_offset (bfd *, const gdb_byte *,
-			    const struct comp_unit_head *,
-			    unsigned int *);
-
 static sect_offset read_abbrev_offset
   (struct dwarf2_per_objfile *dwarf2_per_objfile,
    struct dwarf2_section_info *, sect_offset);
@@ -1512,8 +1472,6 @@ static const char *dwarf_tag_name (unsigned int);
 
 static const char *dwarf_attr_name (unsigned int);
 
-static const char *dwarf_unit_type_name (int unit_type);
-
 static const char *dwarf_form_name (unsigned int);
 
 static const char *dwarf_bool_name (unsigned int);
@@ -1697,16 +1655,6 @@ struct file_and_directory
 static file_and_directory find_file_and_directory (struct die_info *die,
 						   struct dwarf2_cu *cu);
 
-/* Expected enum dwarf_unit_type for read_comp_unit_head.  */
-enum class rcuh_kind { COMPILE, TYPE };
-
-static 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);
-
 static htab_up allocate_signatured_type_table (struct objfile *objfile);
 
 static htab_up allocate_dwo_unit_table (struct objfile *objfile);
@@ -5880,25 +5828,6 @@ dwarf2_build_psymtabs (struct objfile *objfile)
     }
 }
 
-/* Return the total length of the CU described by HEADER.  */
-
-static unsigned int
-get_cu_length (const struct comp_unit_head *header)
-{
-  return header->initial_length_size + header->length;
-}
-
-/* Return TRUE if SECT_OFF is within CU_HEADER.  */
-
-static inline bool
-offset_in_cu_p (const comp_unit_head *cu_header, sect_offset sect_off)
-{
-  sect_offset bottom = cu_header->sect_off;
-  sect_offset top = cu_header->sect_off + get_cu_length (cu_header);
-
-  return sect_off >= bottom && sect_off < top;
-}
-
 /* Find the base address of the compilation unit for range lists and
    location lists.  It will normally be specified by DW_AT_low_pc.
    In DWARF-3 draft 4, the base address could be overridden by
@@ -5930,120 +5859,6 @@ dwarf2_find_base_address (struct die_info *die, struct dwarf2_cu *cu)
     }
 }
 
-/* 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.  */
-
-static 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)
-{
-  int signed_addr;
-  unsigned int bytes_read;
-  const char *filename = section->get_file_name ();
-  bfd *abfd = section->get_bfd_owner ();
-
-  cu_header->length = read_initial_length (abfd, info_ptr, &bytes_read);
-  cu_header->initial_length_size = bytes_read;
-  cu_header->offset_size = (bytes_read == 4) ? 4 : 8;
-  info_ptr += bytes_read;
-  cu_header->version = read_2_bytes (abfd, info_ptr);
-  if (cu_header->version < 2 || cu_header->version > 5)
-    error (_("Dwarf Error: wrong version in compilation unit header "
-	   "(is %d, should be 2, 3, 4 or 5) [in module %s]"),
-	   cu_header->version, filename);
-  info_ptr += 2;
-  if (cu_header->version < 5)
-    switch (section_kind)
-      {
-      case rcuh_kind::COMPILE:
-	cu_header->unit_type = DW_UT_compile;
-	break;
-      case rcuh_kind::TYPE:
-	cu_header->unit_type = DW_UT_type;
-	break;
-      default:
-	internal_error (__FILE__, __LINE__,
-			_("read_comp_unit_head: invalid section_kind"));
-      }
-  else
-    {
-      cu_header->unit_type = static_cast<enum dwarf_unit_type>
-						 (read_1_byte (abfd, info_ptr));
-      info_ptr += 1;
-      switch (cu_header->unit_type)
-	{
-	case DW_UT_compile:
-	case DW_UT_partial:
-	case DW_UT_skeleton:
-	case DW_UT_split_compile:
-	  if (section_kind != rcuh_kind::COMPILE)
-	    error (_("Dwarf Error: wrong unit_type in compilation unit header "
-		   "(is %s, should be %s) [in module %s]"),
-		   dwarf_unit_type_name (cu_header->unit_type),
-		   dwarf_unit_type_name (DW_UT_type), filename);
-	  break;
-	case DW_UT_type:
-	case DW_UT_split_type:
-	  section_kind = rcuh_kind::TYPE;
-	  break;
-	default:
-	  error (_("Dwarf Error: wrong unit_type in compilation unit header "
-		 "(is %#04x, should be one of: %s, %s, %s, %s or %s) "
-		 "[in module %s]"), cu_header->unit_type,
-		 dwarf_unit_type_name (DW_UT_compile),
-		 dwarf_unit_type_name (DW_UT_skeleton),
-		 dwarf_unit_type_name (DW_UT_split_compile),
-		 dwarf_unit_type_name (DW_UT_type),
-		 dwarf_unit_type_name (DW_UT_split_type), filename);
-	}
-
-      cu_header->addr_size = read_1_byte (abfd, info_ptr);
-      info_ptr += 1;
-    }
-  cu_header->abbrev_sect_off = (sect_offset) read_offset (abfd, info_ptr,
-							  cu_header,
-							  &bytes_read);
-  info_ptr += bytes_read;
-  if (cu_header->version < 5)
-    {
-      cu_header->addr_size = read_1_byte (abfd, info_ptr);
-      info_ptr += 1;
-    }
-  signed_addr = bfd_get_sign_extend_vma (abfd);
-  if (signed_addr < 0)
-    internal_error (__FILE__, __LINE__,
-		    _("read_comp_unit_head: dwarf from non elf file"));
-  cu_header->signed_addr_p = signed_addr;
-
-  bool header_has_signature = section_kind == rcuh_kind::TYPE
-    || cu_header->unit_type == DW_UT_skeleton
-    || cu_header->unit_type == DW_UT_split_compile;
-
-  if (header_has_signature)
-    {
-      cu_header->signature = read_8_bytes (abfd, info_ptr);
-      info_ptr += 8;
-    }
-
-  if (section_kind == rcuh_kind::TYPE)
-    {
-      LONGEST type_offset;
-      type_offset = read_offset (abfd, info_ptr, cu_header, &bytes_read);
-      info_ptr += bytes_read;
-      cu_header->type_cu_offset_in_tu = (cu_offset) type_offset;
-      if (to_underlying (cu_header->type_cu_offset_in_tu) != type_offset)
-	error (_("Dwarf Error: Too big type_offset in compilation unit "
-	       "header (is %s) [in module %s]"), plongest (type_offset),
-	       filename);
-    }
-
-  return info_ptr;
-}
-
 /* Helper function that returns the proper abbrev section for
    THIS_CU.  */
 
@@ -6061,62 +5876,6 @@ get_abbrev_section_for_cu (struct dwarf2_per_cu_data *this_cu)
   return abbrev;
 }
 
-/* Subroutine of read_and_check_comp_unit_head and
-   read_and_check_type_unit_head to simplify them.
-   Perform various error checking on the header.  */
-
-static void
-error_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 char *filename = section->get_file_name ();
-
-  if (to_underlying (header->abbrev_sect_off)
-      >= abbrev_section->get_size (dwarf2_per_objfile->objfile))
-    error (_("Dwarf Error: bad offset (%s) in compilation unit header "
-	   "(offset %s + 6) [in module %s]"),
-	   sect_offset_str (header->abbrev_sect_off),
-	   sect_offset_str (header->sect_off),
-	   filename);
-
-  /* Cast to ULONGEST to use 64-bit arithmetic when possible to
-     avoid potential 32-bit overflow.  */
-  if (((ULONGEST) header->sect_off + get_cu_length (header))
-      > section->size)
-    error (_("Dwarf Error: bad length (0x%x) in compilation unit header "
-	   "(offset %s + 0) [in module %s]"),
-	   header->length, sect_offset_str (header->sect_off),
-	   filename);
-}
-
-/* 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.  */
-
-static 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)
-{
-  const gdb_byte *beg_of_comp_unit = info_ptr;
-
-  header->sect_off = (sect_offset) (beg_of_comp_unit - section->buffer);
-
-  info_ptr = read_comp_unit_head (header, info_ptr, section, section_kind);
-
-  header->first_die_cu_offset = (cu_offset) (info_ptr - beg_of_comp_unit);
-
-  error_check_comp_unit_head (dwarf2_per_objfile, header, section,
-			      abbrev_section);
-
-  return info_ptr;
-}
-
 /* Fetch the abbreviation table offset from a comp or type unit header.  */
 
 static sect_offset
@@ -6300,7 +6059,7 @@ create_debug_type_hash_table (struct dwarf2_per_objfile *dwarf2_per_objfile,
       ptr = read_and_check_comp_unit_head (dwarf2_per_objfile, &header, section,
 					   abbrev_section, ptr, section_kind);
 
-      length = get_cu_length (&header);
+      length = header.get_length ();
 
       /* Skip dummy type units.  */
       if (ptr >= info_ptr + length
@@ -6836,7 +6595,7 @@ read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
       gdb_assert (dwo_unit->sect_off == cu->header.sect_off);
       /* For DWOs coming from DWP files, we don't know the CU length
 	 nor the type's offset in the TU until now.  */
-      dwo_unit->length = get_cu_length (&cu->header);
+      dwo_unit->length = cu->header.get_length ();
       dwo_unit->type_offset_in_tu = cu->header.type_cu_offset_in_tu;
 
       /* Establish the type offset that can be used to lookup the type.
@@ -6853,7 +6612,7 @@ read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
       gdb_assert (dwo_unit->sect_off == cu->header.sect_off);
       /* For DWOs coming from DWP files, we don't know the CU length
 	 until now.  */
-      dwo_unit->length = get_cu_length (&cu->header);
+      dwo_unit->length = cu->header.get_length ();
     }
 
   *result_dwo_abbrev_table
@@ -7117,7 +6876,7 @@ cutu_reader::cutu_reader (struct dwarf2_per_cu_data *this_cu,
 
 	  /* LENGTH has not been set yet for type units if we're
 	     using .gdb_index.  */
-	  this_cu->length = get_cu_length (&cu->header);
+	  this_cu->length = cu->header.get_length ();
 
 	  /* Establish the type offset that can be used to lookup the type.  */
 	  sig_type->type_offset_in_section =
@@ -7134,7 +6893,7 @@ cutu_reader::cutu_reader (struct dwarf2_per_cu_data *this_cu,
 						    rcuh_kind::COMPILE);
 
 	  gdb_assert (this_cu->sect_off == cu->header.sect_off);
-	  gdb_assert (this_cu->length == get_cu_length (&cu->header));
+	  gdb_assert (this_cu->length == cu->header.get_length ());
 	  this_cu->dwarf_version = cu->header.version;
 	}
     }
@@ -7290,7 +7049,7 @@ cutu_reader::cutu_reader (struct dwarf2_per_cu_data *this_cu,
       m_new_cu->str_offsets_base = parent_cu->str_offsets_base;
       m_new_cu->addr_base = parent_cu->addr_base;
     }
-  this_cu->length = get_cu_length (&m_new_cu->header);
+  this_cu->length = m_new_cu->header.get_length ();
 
   /* Skip dummy compilation units.  */
   if (info_ptr >= begin_info_ptr + this_cu->length
@@ -13548,7 +13307,7 @@ read_call_site_scope (struct die_info *die, struct dwarf2_cu *cu)
 
 	  sect_offset sect_off
 	    = (sect_offset) dwarf2_get_ref_die_offset (origin);
-	  if (!offset_in_cu_p (&cu->header, sect_off))
+	  if (!cu->header.offset_in_cu_p (sect_off))
 	    {
 	      /* As DW_OP_GNU_parameter_ref uses CU-relative offset this
 		 binding can be done only inside one CU.  Such referenced DIE
@@ -18434,7 +18193,7 @@ find_partial_die (sect_offset sect_off, int offset_in_dwz, struct dwarf2_cu *cu)
   struct partial_die_info *pd = NULL;
 
   if (offset_in_dwz == cu->per_cu->is_dwz
-      && offset_in_cu_p (&cu->header, sect_off))
+      && cu->header.offset_in_cu_p (sect_off))
     {
       pd = cu->find_partial_die (sect_off);
       if (pd != NULL)
@@ -19023,20 +18782,6 @@ read_checked_initial_length_and_offset (bfd *abfd, const gdb_byte *buf,
   return length;
 }
 
-/* Read an offset from the data stream.  The size of the offset is
-   given by cu_header->offset_size.  */
-
-static LONGEST
-read_offset (bfd *abfd, const gdb_byte *buf,
-	     const struct comp_unit_head *cu_header,
-             unsigned int *bytes_read)
-{
-  LONGEST offset = read_offset (abfd, buf, cu_header->offset_size);
-
-  *bytes_read = cu_header->offset_size;
-  return offset;
-}
-
 static const gdb_byte *
 read_n_bytes (bfd *abfd, const gdb_byte *buf, unsigned int size)
 {
@@ -22201,33 +21946,6 @@ dwarf_attr_name (unsigned attr)
   return name;
 }
 
-/* Convert a unit type to corresponding DW_UT name.  */
-
-static const char *
-dwarf_unit_type_name (int unit_type) {
-  switch (unit_type)
-    {
-      case 0x01:
-	return "DW_UT_compile (0x01)";
-      case 0x02:
-	return "DW_UT_type (0x02)";
-      case 0x03:
-	return "DW_UT_partial (0x03)";
-      case 0x04:
-	return "DW_UT_skeleton (0x04)";
-      case 0x05:
-	return "DW_UT_split_compile (0x05)";
-      case 0x06:
-	return "DW_UT_split_type (0x06)";
-      case 0x80:
-	return "DW_UT_lo_user (0x80)";
-      case 0xff:
-	return "DW_UT_hi_user (0xff)";
-      default:
-	return nullptr;
-    }
-}
-
 /* Convert a DWARF value form code into its string name.  */
 
 static const char *
@@ -22533,11 +22251,11 @@ follow_die_offset (sect_offset sect_off, int offset_in_dwz,
       /* .debug_types CUs cannot reference anything outside their CU.
 	 If they need to, they have to reference a signatured type via
 	 DW_FORM_ref_sig8.  */
-      if (!offset_in_cu_p (&cu->header, sect_off))
+      if (!cu->header.offset_in_cu_p (sect_off))
 	return NULL;
     }
   else if (offset_in_dwz != cu->per_cu->is_dwz
-	   || !offset_in_cu_p (&cu->header, sect_off))
+	   || !cu->header.offset_in_cu_p (sect_off))
     {
       struct dwarf2_per_cu_data *per_cu;