Introduce partial_symtab::read_symtab method

This introduces a new partial_symtab::read_symtab method, and updates
the symbol readers to subclass partial_symtab and implement this
method.  The old read_symtab and read_symtab_private members are
removed.

In practice, only DWARF and CTF are truly updated to take advantage of
the new setup.  The other symbol readers are less actively maintained,
and so this patch also introduces a "legacy_psymtab", which
essentially works the same way as the old partial_symtab.

(Note that, without more knowledge of the interaction between these
symbol readers, fixing this to remove the new (small) overhead is not
trivial, because these readers copy the read_symtab pointer between
partial symtabs.)

gdb/ChangeLog
2020-01-26  Tom Tromey  <tom@tromey.com>

	* xcoffread.c (this_symtab_psymtab, read_xcoff_symtab)
	(xcoff_psymtab_to_symtab_1, xcoff_read_symtab)
	(xcoff_start_psymtab, xcoff_end_psymtab, scan_xcoff_symtab): Use
	legacy_symtab.
	* stabsread.h (dbx_end_psymtab): Use legacy_symtab.
	* psymtab.c (psymtab_to_symtab): Call method.
	(dump_psymtab): Update.
	* psympriv.h (struct partial_symtab): Add virtual destructor.
	<read_symtab>: New method.
	(struct legacy_symtab): New.
	* mdebugread.c (mdebug_read_symtab): Use legacy_psymtab.
	(struct pst_map) <pst>: Now a legacy_psymtab.
	(parse_procedure, parse_partial_symbols, psymtab_to_symtab_1)
	(new_psymtab): Use legacy_psymtab.
	* dwarf2read.h (struct dwarf2_psymtab): New.
	(struct dwarf2_per_cu_data) <psymtab>: Use it.
	* dwarf2read.c (dwarf2_create_include_psymtab)
	(dwarf2_build_include_psymtabs, create_type_unit_group)
	(create_partial_symtab, process_psymtab_comp_unit_reader)
	(build_type_psymtabs_reader, build_type_psymtab_dependencies)
	(set_partial_user): Use dwarf2_psymtab.
	(dwarf2_psymtab::read_symtab): Rename from dwarf2_read_symtab.
	(psymtab_to_symtab_1, process_full_comp_unit)
	(process_full_type_unit, dwarf2_ranges_read)
	(dwarf2_get_pc_bounds, psymtab_include_file_name)
	(dwarf_decode_lines): Use dwarf2_psymtab.
	* dwarf-index-write.c (psym_index_map): Use dwarf2_psymtab.
	(add_address_entry_worker, write_one_signatured_type)
	(recursively_count_psymbols, recursively_write_psymbols)
	(write_one_signatured_type, psyms_seen_size, write_gdbindex)
	(write_debug_names): Likewise.
	* dbxread.c (struct header_file_location): Take a legacy_psymtab.
	<pst>: Now a legacy_psymtab.
	(find_corresponding_bincl_psymtab): Return a legacy_psymtab.
	(read_dbx_symtab, start_psymtab, dbx_end_psymtab)
	(dbx_psymtab_to_symtab_1, read_ofile_symtab): Use legacy_psymtab.
	* ctfread.c (struct ctf_psymtab): New.
	(ctf_start_symtab, ctf_end_symtab, psymtab_to_symtab): Take a
	ctf_psymtab.
	(ctf_psymtab::read_symtab): Rename from ctf_read_symtab.
	(create_partial_symtab): Return a ctf_psymtab.
	(scan_partial_symbols): Update.

Change-Id: Ia57a828786867d6ad03200af8f996f48ed15285e

1 files changed, 33 insertions, 1 deletions

diff --git a/gdb/psympriv.h b/gdb/psympriv.h
index 82ae1b5..4c189aa 100644
--- a/gdb/psympriv.h
+++ b/gdb/psympriv.h
@@ -121,6 +121,14 @@ struct partial_symtab
 		  CORE_ADDR addr)
     ATTRIBUTE_NONNULL (2) ATTRIBUTE_NONNULL (3);
 
+  virtual ~partial_symtab ()
+  {
+  }
+
+  /* Read the full symbol table corresponding to this partial symbol
+     table.  */
+  virtual void read_symtab (struct objfile *) = 0;
+
   /* Return the raw low text address of this partial_symtab.  */
   CORE_ADDR raw_text_low () const
   {
@@ -278,11 +286,35 @@ struct partial_symtab
      !readin or if we haven't looked for the symtab after it was readin.  */
 
   struct compunit_symtab *compunit_symtab = nullptr;
+};
+
+/* A partial_symtab that works in the historical db way.  This should
+   not be used in new code, but exists to transition the somewhat
+   unmaintained "legacy" debug formats.  */
+
+struct legacy_psymtab : public partial_symtab
+{
+  legacy_psymtab (const char *filename, struct objfile *objfile)
+    : partial_symtab (filename, objfile)
+  {
+  }
+
+  legacy_psymtab (const char *filename, struct objfile *objfile,
+		  CORE_ADDR addr)
+    : partial_symtab (filename, objfile, addr)
+  {
+  }
+
+  void read_symtab (struct objfile *objf) override
+  {
+    if (legacy_read_symtab)
+      (*legacy_read_symtab) (this, objf);
+  }
 
   /* Pointer to function which will read in the symtab corresponding to
      this psymtab.  */
 
-  void (*read_symtab) (struct partial_symtab *, struct objfile *) = nullptr;
+  void (*legacy_read_symtab) (legacy_psymtab *, struct objfile *) = nullptr;
 
   /* Information that lets read_symtab() locate the part of the symbol table
      that this psymtab corresponds to.  This information is private to the