[PATCH 1/3] Move dwarf2_cu to new header file

[Tom Tromey <tom@tromey.com>]

This moves dwarf2_cu and one supporting data structure to a new header
file.  The main goal, as always with this kind of change, is to make
the DWARF reader a bit more understandable.

gdb/ChangeLog
2021-03-27  Tom Tromey  <tom@tromey.com>

	* Makefile.in (HFILES_NO_SRCDIR): Add dwarf2/cu.h.
	* dwarf2/read.c (struct delayed_method_info, struct dwarf2_cu):
	Move to cu.h.
	* dwarf2/cu.h: New file.
---
 gdb/ChangeLog     |   7 ++
 gdb/Makefile.in   |   1 +
 gdb/dwarf2/cu.h   | 270 ++++++++++++++++++++++++++++++++++++++++++++++
 gdb/dwarf2/read.c | 245 +----------------------------------------
 4 files changed, 279 insertions(+), 244 deletions(-)
 create mode 100644 gdb/dwarf2/cu.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 3318c1a5215..359fd11a4de 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1273,6 +1273,7 @@ HFILES_NO_SRCDIR = \
 	dictionary.h \
 	disasm.h \
 	dummy-frame.h \
+	dwarf2/cu.h \
 	dwarf2/frame-tailcall.h \
 	dwarf2/frame.h \
 	dwarf2/expr.h \
diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h
new file mode 100644
index 00000000000..9fb2d61163a
--- /dev/null
+++ b/gdb/dwarf2/cu.h
@@ -0,0 +1,270 @@
+/* DWARF CU data structure
+
+   Copyright (C) 2021 Free Software Foundation, Inc.
+
+   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_CU_H
+#define GDB_DWARF2_CU_H
+
+#include "buildsym.h"
+#include "dwarf2/comp-unit.h"
+#include "gdbsupport/gdb_optional.h"
+
+/* Type used for delaying computation of method physnames.
+   See comments for compute_delayed_physnames.  */
+struct delayed_method_info
+{
+  /* The type to which the method is attached, i.e., its parent class.  */
+  struct type *type;
+
+  /* The index of the method in the type's function fieldlists.  */
+  int fnfield_index;
+
+  /* The index of the method in the fieldlist.  */
+  int index;
+
+  /* The name of the DIE.  */
+  const char *name;
+
+  /*  The DIE associated with this method.  */
+  struct die_info *die;
+};
+
+/* Internal state when decoding a particular compilation unit.  */
+struct dwarf2_cu
+{
+  explicit dwarf2_cu (dwarf2_per_cu_data *per_cu,
+		      dwarf2_per_objfile *per_objfile);
+
+  DISABLE_COPY_AND_ASSIGN (dwarf2_cu);
+
+  /* TU version of handle_DW_AT_stmt_list for read_type_unit_scope.
+     Create the set of symtabs used by this TU, or if this TU is sharing
+     symtabs with another TU and the symtabs have already been created
+     then restore those symtabs in the line header.
+     We don't need the pc/line-number mapping for type units.  */
+  void setup_type_unit_groups (struct die_info *die);
+
+  /* Start a symtab for DWARF.  NAME, COMP_DIR, LOW_PC are passed to the
+     buildsym_compunit constructor.  */
+  struct compunit_symtab *start_symtab (const char *name,
+					const char *comp_dir,
+					CORE_ADDR low_pc);
+
+  /* Reset the builder.  */
+  void reset_builder () { m_builder.reset (); }
+
+  /* Return a type that is a generic pointer type, the size of which
+     matches the address size given in the compilation unit header for
+     this CU.  */
+  struct type *addr_type () const;
+
+  /* Find an integer type the same size as the address size given in
+     the compilation unit header for this CU.  UNSIGNED_P controls if
+     the integer is unsigned or not.  */
+  struct type *addr_sized_int_type (bool unsigned_p) const;
+
+  /* The header of the compilation unit.  */
+  struct comp_unit_head header {};
+
+  /* Base address of this compilation unit.  */
+  gdb::optional<CORE_ADDR> base_address;
+
+  /* The language we are debugging.  */
+  enum language language = language_unknown;
+  const struct language_defn *language_defn = nullptr;
+
+  const char *producer = nullptr;
+
+private:
+  /* The symtab builder for this CU.  This is only non-NULL when full
+     symbols are being read.  */
+  std::unique_ptr<buildsym_compunit> m_builder;
+
+public:
+  /* The generic symbol table building routines have separate lists for
+     file scope symbols and all all other scopes (local scopes).  So
+     we need to select the right one to pass to add_symbol_to_list().
+     We do it by keeping a pointer to the correct list in list_in_scope.
+
+     FIXME: The original dwarf code just treated the file scope as the
+     first local scope, and all other local scopes as nested local
+     scopes, and worked fine.  Check to see if we really need to
+     distinguish these in buildsym.c.  */
+  struct pending **list_in_scope = nullptr;
+
+  /* Hash table holding all the loaded partial DIEs
+     with partial_die->offset.SECT_OFF as hash.  */
+  htab_t partial_dies = nullptr;
+
+  /* Storage for things with the same lifetime as this read-in compilation
+     unit, including partial DIEs.  */
+  auto_obstack comp_unit_obstack;
+
+  /* Backlink to our per_cu entry.  */
+  struct dwarf2_per_cu_data *per_cu;
+
+  /* The dwarf2_per_objfile that owns this.  */
+  dwarf2_per_objfile *per_objfile;
+
+  /* How many compilation units ago was this CU last referenced?  */
+  int last_used = 0;
+
+  /* A hash table of DIE cu_offset for following references with
+     die_info->offset.sect_off as hash.  */
+  htab_t die_hash = nullptr;
+
+  /* Full DIEs if read in.  */
+  struct die_info *dies = nullptr;
+
+  /* A set of pointers to dwarf2_per_cu_data objects for compilation
+     units referenced by this one.  Only set during full symbol processing;
+     partial symbol tables do not have dependencies.  */
+  htab_t dependencies = nullptr;
+
+  /* Header data from the line table, during full symbol processing.  */
+  struct line_header *line_header = nullptr;
+  /* Non-NULL if LINE_HEADER is owned by this DWARF_CU.  Otherwise,
+     it's owned by dwarf2_per_bfd::line_header_hash.  If non-NULL,
+     this is the DW_TAG_compile_unit die for this CU.  We'll hold on
+     to the line header as long as this DIE is being processed.  See
+     process_die_scope.  */
+  die_info *line_header_die_owner = nullptr;
+
+  /* A list of methods which need to have physnames computed
+     after all type information has been read.  */
+  std::vector<delayed_method_info> method_list;
+
+  /* To be copied to symtab->call_site_htab.  */
+  htab_t call_site_htab = nullptr;
+
+  /* Non-NULL if this CU came from a DWO file.
+     There is an invariant here that is important to remember:
+     Except for attributes copied from the top level DIE in the "main"
+     (or "stub") file in preparation for reading the DWO file
+     (e.g., DW_AT_addr_base), we KISS: there is only *one* CU.
+     Either there isn't a DWO file (in which case this is NULL and the point
+     is moot), or there is and either we're not going to read it (in which
+     case this is NULL) or there is and we are reading it (in which case this
+     is non-NULL).  */
+  struct dwo_unit *dwo_unit = nullptr;
+
+  /* The DW_AT_addr_base (DW_AT_GNU_addr_base) attribute if present.
+     Note this value comes from the Fission stub CU/TU's DIE.  */
+  gdb::optional<ULONGEST> addr_base;
+
+  /* The DW_AT_GNU_ranges_base attribute, if present.
+
+     This is only relevant in the context of pre-DWARF 5 split units.  In this
+     context, there is a .debug_ranges section in the linked executable,
+     containing all the ranges data for all the compilation units.  Each
+     skeleton/stub unit has (if needed) a DW_AT_GNU_ranges_base attribute that
+     indicates the base of its contribution to that section.  The DW_AT_ranges
+     attributes in the split-unit are of the form DW_FORM_sec_offset and point
+     into the .debug_ranges section of the linked file.  However, they are not
+     "true" DW_FORM_sec_offset, because they are relative to the base of their
+     compilation unit's contribution, rather than relative to the beginning of
+     the section.  The DW_AT_GNU_ranges_base value must be added to it to make
+     it relative to the beginning of the section.
+
+     Note that the value is zero when we are not in a pre-DWARF 5 split-unit
+     case, so this value can be added without needing to know whether we are in
+     this case or not.
+
+     N.B. If a DW_AT_ranges attribute is found on the DW_TAG_compile_unit in the
+     skeleton/stub, it must not have the base added, as it already points to the
+     right place.  And since the DW_TAG_compile_unit DIE in the split-unit can't
+     have a DW_AT_ranges attribute, we can use the
+
+       die->tag != DW_AT_compile_unit
+
+     to determine whether the base should be added or not.  */
+  ULONGEST gnu_ranges_base = 0;
+
+  /* The DW_AT_rnglists_base attribute, if present.
+
+     This is used when processing attributes of form DW_FORM_rnglistx in
+     non-split units.  Attributes of this form found in a split unit don't
+     use it, as split-unit files have their own non-shared .debug_rnglists.dwo
+     section.  */
+  ULONGEST rnglists_base = 0;
+
+  /* The DW_AT_loclists_base attribute if present.  */
+  ULONGEST loclist_base = 0;
+
+  /* When reading debug info generated by older versions of rustc, we
+     have to rewrite some union types to be struct types with a
+     variant part.  This rewriting must be done after the CU is fully
+     read in, because otherwise at the point of rewriting some struct
+     type might not have been fully processed.  So, we keep a list of
+     all such types here and process them after expansion.  */
+  std::vector<struct type *> rust_unions;
+
+  /* The DW_AT_str_offsets_base attribute if present.  For DWARF 4 version DWO
+     files, the value is implicitly zero.  For DWARF 5 version DWO files, the
+     value is often implicit and is the size of the header of
+     .debug_str_offsets section (8 or 4, depending on the address size).  */
+  gdb::optional<ULONGEST> str_offsets_base;
+
+  /* Mark used when releasing cached dies.  */
+  bool mark : 1;
+
+  /* This CU references .debug_loc.  See the symtab->locations_valid field.
+     This test is imperfect as there may exist optimized debug code not using
+     any location list and still facing inlining issues if handled as
+     unoptimized code.  For a future better test see GCC PR other/32998.  */
+  bool has_loclist : 1;
+
+  /* These cache the results for producer_is_* fields.  CHECKED_PRODUCER is true
+     if all the producer_is_* fields are valid.  This information is cached
+     because profiling CU expansion showed excessive time spent in
+     producer_is_gxx_lt_4_6.  */
+  bool checked_producer : 1;
+  bool producer_is_gxx_lt_4_6 : 1;
+  bool producer_is_gcc_lt_4_3 : 1;
+  bool producer_is_icc : 1;
+  bool producer_is_icc_lt_14 : 1;
+  bool producer_is_codewarrior : 1;
+
+  /* When true, the file that we're processing is known to have
+     debugging info for C++ namespaces.  GCC 3.3.x did not produce
+     this information, but later versions do.  */
+
+  bool processing_has_namespace_info : 1;
+
+  struct partial_die_info *find_partial_die (sect_offset sect_off);
+
+  /* If this CU was inherited by another CU (via specification,
+     abstract_origin, etc), this is the ancestor CU.  */
+  dwarf2_cu *ancestor;
+
+  /* Get the buildsym_compunit for this CU.  */
+  buildsym_compunit *get_builder ()
+  {
+    /* If this CU has a builder associated with it, use that.  */
+    if (m_builder != nullptr)
+      return m_builder.get ();
+
+    /* Otherwise, search ancestors for a valid builder.  */
+    if (ancestor != nullptr)
+      return ancestor->get_builder ();
+
+    return nullptr;
+  }
+};
+
+#endif /* GDB_DWARF2_CU_H */
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index b324541ee9f..b11fd0580f7 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -33,6 +33,7 @@
 #include "dwarf2/abbrev.h"
 #include "dwarf2/attribute.h"
 #include "dwarf2/comp-unit.h"
+#include "dwarf2/cu.h"
 #include "dwarf2/index-cache.h"
 #include "dwarf2/index-common.h"
 #include "dwarf2/leb.h"
@@ -49,7 +50,6 @@
 #include "gdbtypes.h"
 #include "objfiles.h"
 #include "dwarf2.h"
-#include "buildsym.h"
 #include "demangle.h"
 #include "gdb-demangle.h"
 #include "filenames.h"	/* for DOSish file names */
@@ -409,249 +409,6 @@ struct loclists_rnglists_header
   unsigned int offset_entry_count;
 };
 
-/* Type used for delaying computation of method physnames.
-   See comments for compute_delayed_physnames.  */
-struct delayed_method_info
-{
-  /* The type to which the method is attached, i.e., its parent class.  */
-  struct type *type;
-
-  /* The index of the method in the type's function fieldlists.  */
-  int fnfield_index;
-
-  /* The index of the method in the fieldlist.  */
-  int index;
-
-  /* The name of the DIE.  */
-  const char *name;
-
-  /*  The DIE associated with this method.  */
-  struct die_info *die;
-};
-
-/* Internal state when decoding a particular compilation unit.  */
-struct dwarf2_cu
-{
-  explicit dwarf2_cu (dwarf2_per_cu_data *per_cu,
-		      dwarf2_per_objfile *per_objfile);
-
-  DISABLE_COPY_AND_ASSIGN (dwarf2_cu);
-
-  /* TU version of handle_DW_AT_stmt_list for read_type_unit_scope.
-     Create the set of symtabs used by this TU, or if this TU is sharing
-     symtabs with another TU and the symtabs have already been created
-     then restore those symtabs in the line header.
-     We don't need the pc/line-number mapping for type units.  */
-  void setup_type_unit_groups (struct die_info *die);
-
-  /* Start a symtab for DWARF.  NAME, COMP_DIR, LOW_PC are passed to the
-     buildsym_compunit constructor.  */
-  struct compunit_symtab *start_symtab (const char *name,
-					const char *comp_dir,
-					CORE_ADDR low_pc);
-
-  /* Reset the builder.  */
-  void reset_builder () { m_builder.reset (); }
-
-  /* Return a type that is a generic pointer type, the size of which
-     matches the address size given in the compilation unit header for
-     this CU.  */
-  struct type *addr_type () const;
-
-  /* Find an integer type the same size as the address size given in
-     the compilation unit header for this CU.  UNSIGNED_P controls if
-     the integer is unsigned or not.  */
-  struct type *addr_sized_int_type (bool unsigned_p) const;
-
-  /* The header of the compilation unit.  */
-  struct comp_unit_head header {};
-
-  /* Base address of this compilation unit.  */
-  gdb::optional<CORE_ADDR> base_address;
-
-  /* The language we are debugging.  */
-  enum language language = language_unknown;
-  const struct language_defn *language_defn = nullptr;
-
-  const char *producer = nullptr;
-
-private:
-  /* The symtab builder for this CU.  This is only non-NULL when full
-     symbols are being read.  */
-  std::unique_ptr<buildsym_compunit> m_builder;
-
-public:
-  /* The generic symbol table building routines have separate lists for
-     file scope symbols and all all other scopes (local scopes).  So
-     we need to select the right one to pass to add_symbol_to_list().
-     We do it by keeping a pointer to the correct list in list_in_scope.
-
-     FIXME: The original dwarf code just treated the file scope as the
-     first local scope, and all other local scopes as nested local
-     scopes, and worked fine.  Check to see if we really need to
-     distinguish these in buildsym.c.  */
-  struct pending **list_in_scope = nullptr;
-
-  /* Hash table holding all the loaded partial DIEs
-     with partial_die->offset.SECT_OFF as hash.  */
-  htab_t partial_dies = nullptr;
-
-  /* Storage for things with the same lifetime as this read-in compilation
-     unit, including partial DIEs.  */
-  auto_obstack comp_unit_obstack;
-
-  /* Backlink to our per_cu entry.  */
-  struct dwarf2_per_cu_data *per_cu;
-
-  /* The dwarf2_per_objfile that owns this.  */
-  dwarf2_per_objfile *per_objfile;
-
-  /* How many compilation units ago was this CU last referenced?  */
-  int last_used = 0;
-
-  /* A hash table of DIE cu_offset for following references with
-     die_info->offset.sect_off as hash.  */
-  htab_t die_hash = nullptr;
-
-  /* Full DIEs if read in.  */
-  struct die_info *dies = nullptr;
-
-  /* A set of pointers to dwarf2_per_cu_data objects for compilation
-     units referenced by this one.  Only set during full symbol processing;
-     partial symbol tables do not have dependencies.  */
-  htab_t dependencies = nullptr;
-
-  /* Header data from the line table, during full symbol processing.  */
-  struct line_header *line_header = nullptr;
-  /* Non-NULL if LINE_HEADER is owned by this DWARF_CU.  Otherwise,
-     it's owned by dwarf2_per_bfd::line_header_hash.  If non-NULL,
-     this is the DW_TAG_compile_unit die for this CU.  We'll hold on
-     to the line header as long as this DIE is being processed.  See
-     process_die_scope.  */
-  die_info *line_header_die_owner = nullptr;
-
-  /* A list of methods which need to have physnames computed
-     after all type information has been read.  */
-  std::vector<delayed_method_info> method_list;
-
-  /* To be copied to symtab->call_site_htab.  */
-  htab_t call_site_htab = nullptr;
-
-  /* Non-NULL if this CU came from a DWO file.
-     There is an invariant here that is important to remember:
-     Except for attributes copied from the top level DIE in the "main"
-     (or "stub") file in preparation for reading the DWO file
-     (e.g., DW_AT_addr_base), we KISS: there is only *one* CU.
-     Either there isn't a DWO file (in which case this is NULL and the point
-     is moot), or there is and either we're not going to read it (in which
-     case this is NULL) or there is and we are reading it (in which case this
-     is non-NULL).  */
-  struct dwo_unit *dwo_unit = nullptr;
-
-  /* The DW_AT_addr_base (DW_AT_GNU_addr_base) attribute if present.
-     Note this value comes from the Fission stub CU/TU's DIE.  */
-  gdb::optional<ULONGEST> addr_base;
-
-  /* The DW_AT_GNU_ranges_base attribute, if present.
-
-     This is only relevant in the context of pre-DWARF 5 split units.  In this
-     context, there is a .debug_ranges section in the linked executable,
-     containing all the ranges data for all the compilation units.  Each
-     skeleton/stub unit has (if needed) a DW_AT_GNU_ranges_base attribute that
-     indicates the base of its contribution to that section.  The DW_AT_ranges
-     attributes in the split-unit are of the form DW_FORM_sec_offset and point
-     into the .debug_ranges section of the linked file.  However, they are not
-     "true" DW_FORM_sec_offset, because they are relative to the base of their
-     compilation unit's contribution, rather than relative to the beginning of
-     the section.  The DW_AT_GNU_ranges_base value must be added to it to make
-     it relative to the beginning of the section.
-
-     Note that the value is zero when we are not in a pre-DWARF 5 split-unit
-     case, so this value can be added without needing to know whether we are in
-     this case or not.
-
-     N.B. If a DW_AT_ranges attribute is found on the DW_TAG_compile_unit in the
-     skeleton/stub, it must not have the base added, as it already points to the
-     right place.  And since the DW_TAG_compile_unit DIE in the split-unit can't
-     have a DW_AT_ranges attribute, we can use the
-
-       die->tag != DW_AT_compile_unit
-
-     to determine whether the base should be added or not.  */
-  ULONGEST gnu_ranges_base = 0;
-
-  /* The DW_AT_rnglists_base attribute, if present.
-
-     This is used when processing attributes of form DW_FORM_rnglistx in
-     non-split units.  Attributes of this form found in a split unit don't
-     use it, as split-unit files have their own non-shared .debug_rnglists.dwo
-     section.  */
-  ULONGEST rnglists_base = 0;
-
-  /* The DW_AT_loclists_base attribute if present.  */
-  ULONGEST loclist_base = 0;
-
-  /* When reading debug info generated by older versions of rustc, we
-     have to rewrite some union types to be struct types with a
-     variant part.  This rewriting must be done after the CU is fully
-     read in, because otherwise at the point of rewriting some struct
-     type might not have been fully processed.  So, we keep a list of
-     all such types here and process them after expansion.  */
-  std::vector<struct type *> rust_unions;
-
-  /* The DW_AT_str_offsets_base attribute if present.  For DWARF 4 version DWO
-     files, the value is implicitly zero.  For DWARF 5 version DWO files, the
-     value is often implicit and is the size of the header of
-     .debug_str_offsets section (8 or 4, depending on the address size).  */
-  gdb::optional<ULONGEST> str_offsets_base;
-
-  /* Mark used when releasing cached dies.  */
-  bool mark : 1;
-
-  /* This CU references .debug_loc.  See the symtab->locations_valid field.
-     This test is imperfect as there may exist optimized debug code not using
-     any location list and still facing inlining issues if handled as
-     unoptimized code.  For a future better test see GCC PR other/32998.  */
-  bool has_loclist : 1;
-
-  /* These cache the results for producer_is_* fields.  CHECKED_PRODUCER is true
-     if all the producer_is_* fields are valid.  This information is cached
-     because profiling CU expansion showed excessive time spent in
-     producer_is_gxx_lt_4_6.  */
-  bool checked_producer : 1;
-  bool producer_is_gxx_lt_4_6 : 1;
-  bool producer_is_gcc_lt_4_3 : 1;
-  bool producer_is_icc : 1;
-  bool producer_is_icc_lt_14 : 1;
-  bool producer_is_codewarrior : 1;
-
-  /* When true, the file that we're processing is known to have
-     debugging info for C++ namespaces.  GCC 3.3.x did not produce
-     this information, but later versions do.  */
-
-  bool processing_has_namespace_info : 1;
-
-  struct partial_die_info *find_partial_die (sect_offset sect_off);
-
-  /* If this CU was inherited by another CU (via specification,
-     abstract_origin, etc), this is the ancestor CU.  */
-  dwarf2_cu *ancestor;
-
-  /* Get the buildsym_compunit for this CU.  */
-  buildsym_compunit *get_builder ()
-  {
-    /* If this CU has a builder associated with it, use that.  */
-    if (m_builder != nullptr)
-      return m_builder.get ();
-
-    /* Otherwise, search ancestors for a valid builder.  */
-    if (ancestor != nullptr)
-      return ancestor->get_builder ();
-
-    return nullptr;
-  }
-};
-
 /* A struct that can be used as a hash key for tables based on DW_AT_stmt_list.
    This includes type_unit_group and quick_file_names.  */
 
-- 
2.26.2