Introduce minimal_symbol_reader

This patch introduced minimal_symbol_reader, a RAII-based class which
replaces the current make_cleanup_discard_minimal_symbols.

2016-10-21  Tom Tromey  <tom@tromey.com>

	* xcoffread.c (xcoff_initial_scan): Use
	minimal_symbol_reader.
	* mipsread.c (mipscoff_symfile_read): Use
	minimal_symbol_reader.
	* minsyms.h (minimal_symbol_reader): New class.
	(init_minimal_symbol_collection)
	(make_cleanup_discard_minimal_symbols, install_minimal_symbols):
	Don't declare.
	* minsyms.c (minimal_symbol_reader): Renamed from
	init_minimal_symbol_collection, turned into constructor.
	(~minimal_symbol_reader): Renamed from
	do_discard_minimal_symbols_cleanup, turned into destructor.
	(make_cleanup_discard_minimal_symbols): Remove.
	(minimal_symbol_reader::install): Rename form
	install_minimal_symbols.
	* mdebugread.c (elfmdebug_build_psymtabs): Use
	minimal_symbol_reader.
	* machoread.c (macho_symfile_read): Use
	minimal_symbol_reader.
	* elfread.c (elf_read_minimal_symbols): Use
	minimal_symbol_reader.
	* dbxread.c (dbx_symfile_read): Use minimal_symbol_reader.
	* coffread.c (coff_symfile_read): Use
	minimal_symbol_reader.

10 files changed, 89 insertions, 82 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ebfdf99..017396c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,32 @@
 2016-10-21  Tom Tromey  <tom@tromey.com>
 
+	* xcoffread.c (xcoff_initial_scan): Use
+	minimal_symbol_reader.
+	* mipsread.c (mipscoff_symfile_read): Use
+	minimal_symbol_reader.
+	* minsyms.h (minimal_symbol_reader): New class.
+	(init_minimal_symbol_collection)
+	(make_cleanup_discard_minimal_symbols, install_minimal_symbols):
+	Don't declare.
+	* minsyms.c (minimal_symbol_reader): Renamed from
+	init_minimal_symbol_collection, turned into constructor.
+	(~minimal_symbol_reader): Renamed from
+	do_discard_minimal_symbols_cleanup, turned into destructor.
+	(make_cleanup_discard_minimal_symbols): Remove.
+	(minimal_symbol_reader::install): Rename form
+	install_minimal_symbols.
+	* mdebugread.c (elfmdebug_build_psymtabs): Use
+	minimal_symbol_reader.
+	* machoread.c (macho_symfile_read): Use
+	minimal_symbol_reader.
+	* elfread.c (elf_read_minimal_symbols): Use
+	minimal_symbol_reader.
+	* dbxread.c (dbx_symfile_read): Use minimal_symbol_reader.
+	* coffread.c (coff_symfile_read): Use
+	minimal_symbol_reader.
+
+2016-10-21  Tom Tromey  <tom@tromey.com>
+
 	* top.c (new_ui_command, wait_sync_command_done)
 	(gdb_readline_wrapper): Use scoped_restore.
 	* infrun.c (fetch_inferior_event): Use scoped_restore.
diff --git a/gdb/coffread.c b/gdb/coffread.c
index 830deb5..67b9cb7 100644
--- a/gdb/coffread.c
+++ b/gdb/coffread.c
@@ -568,7 +568,7 @@ coff_symfile_read (struct objfile *objfile, int symfile_flags)
   unsigned int num_symbols;
   int symtab_offset;
   int stringtab_offset;
-  struct cleanup *back_to, *cleanup_minimal_symbols;
+  struct cleanup *back_to;
   int stabstrsize;
   
   info = (struct coff_symfile_info *) objfile_data (objfile,
@@ -645,8 +645,7 @@ coff_symfile_read (struct objfile *objfile, int symfile_flags)
   if (val < 0)
     error (_("\"%s\": can't get string table"), name);
 
-  init_minimal_symbol_collection ();
-  cleanup_minimal_symbols = make_cleanup_discard_minimal_symbols ();
+  minimal_symbol_reader reader;
 
   /* Now that the executable file is positioned at symbol table,
      process it and define symbols accordingly.  */
@@ -656,7 +655,7 @@ coff_symfile_read (struct objfile *objfile, int symfile_flags)
   /* Install any minimal symbols that have been collected as the
      current minimal symbols for this objfile.  */
 
-  install_minimal_symbols (objfile);
+  reader.install (objfile);
 
   if (pe_file)
     {
@@ -699,9 +698,6 @@ coff_symfile_read (struct objfile *objfile, int symfile_flags)
 	}
     }
 
-  /* Free the installed minimal symbol data.  */
-  do_cleanups (cleanup_minimal_symbols);
-
   bfd_map_over_sections (abfd, coff_locate_sections, (void *) info);
 
   if (info->stabsects)
diff --git a/gdb/dbxread.c b/gdb/dbxread.c
index d5a9587..26d50e1 100644
--- a/gdb/dbxread.c
+++ b/gdb/dbxread.c
@@ -558,8 +558,7 @@ dbx_symfile_read (struct objfile *objfile, int symfile_flags)
   free_pending_blocks ();
   back_to = make_cleanup (really_free_pendings, 0);
 
-  init_minimal_symbol_collection ();
-  make_cleanup_discard_minimal_symbols ();
+  minimal_symbol_reader reader;
 
   /* Read stabs data from executable file and define symbols.  */
 
@@ -572,7 +571,7 @@ dbx_symfile_read (struct objfile *objfile, int symfile_flags)
   /* Install any minimal symbols that have been collected as the current
      minimal symbols for this objfile.  */
 
-  install_minimal_symbols (objfile);
+  reader.install (objfile);
 
   do_cleanups (back_to);
 }
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 84355cf..4f55e37 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -1049,8 +1049,8 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
       return;
     }
 
-  init_minimal_symbol_collection ();
-  back_to = make_cleanup_discard_minimal_symbols ();
+  minimal_symbol_reader reader;
+  back_to = make_cleanup (null_cleanup, NULL);
 
   /* Allocate struct to keep track of the symfile.  */
   dbx = XCNEW (struct dbx_symfile_info);
@@ -1149,7 +1149,7 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
      responsibility to install them.  "mdebug" appears to be the only one
      which will do this.  */
 
-  install_minimal_symbols (objfile);
+  reader.install (objfile);
   do_cleanups (back_to);
 
   if (symtab_create_debug)
diff --git a/gdb/machoread.c b/gdb/machoread.c
index 2eff534..45ae67b 100644
--- a/gdb/machoread.c
+++ b/gdb/machoread.c
@@ -855,8 +855,7 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
 	  symbol_table = (asymbol **) xmalloc (storage_needed);
 	  make_cleanup (xfree, symbol_table);
 
-          init_minimal_symbol_collection ();
-          make_cleanup_discard_minimal_symbols ();
+          minimal_symbol_reader reader;
 
 	  symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table);
 
@@ -867,7 +866,7 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
 
 	  macho_symtab_read (objfile, symcount, symbol_table, &oso_vector);
 
-          install_minimal_symbols (objfile);
+          reader.install (objfile);
 	}
 
       /* Try to read .eh_frame / .debug_frame.  */
diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
index 157ce77..358ee70 100644
--- a/gdb/mdebugread.c
+++ b/gdb/mdebugread.c
@@ -4870,14 +4870,12 @@ elfmdebug_build_psymtabs (struct objfile *objfile,
 {
   bfd *abfd = objfile->obfd;
   struct ecoff_debug_info *info;
-  struct cleanup *back_to;
 
   /* FIXME: It's not clear whether we should be getting minimal symbol
      information from .mdebug in an ELF file, or whether we will.
      Re-initialize the minimal symbol reader in case we do.  */
 
-  init_minimal_symbol_collection ();
-  back_to = make_cleanup_discard_minimal_symbols ();
+  minimal_symbol_reader reader;
 
   info = ((struct ecoff_debug_info *)
 	  obstack_alloc (&objfile->objfile_obstack,
@@ -4889,8 +4887,7 @@ elfmdebug_build_psymtabs (struct objfile *objfile,
 
   mdebug_build_psymtabs (objfile, swap, info);
 
-  install_minimal_symbols (objfile);
-  do_cleanups (back_to);
+  reader.install (objfile);
 }
 
 void
diff --git a/gdb/minsyms.c b/gdb/minsyms.c
index b478402..a100d4c 100644
--- a/gdb/minsyms.c
+++ b/gdb/minsyms.c
@@ -921,8 +921,7 @@ get_symbol_leading_char (bfd *abfd)
 
 /* See minsyms.h.  */
 
-void
-init_minimal_symbol_collection (void)
+minimal_symbol_reader::minimal_symbol_reader ()
 {
   msym_count = 0;
   msym_bunch = NULL;
@@ -932,6 +931,26 @@ init_minimal_symbol_collection (void)
   msym_bunch_index = BUNCH_SIZE;
 }
 
+/* Discard the currently collected minimal symbols, if any.  If we wish
+   to save them for later use, we must have already copied them somewhere
+   else before calling this function.
+
+   FIXME:  We could allocate the minimal symbol bunches on their own
+   obstack and then simply blow the obstack away when we are done with
+   it.  Is it worth the extra trouble though?  */
+
+minimal_symbol_reader::~minimal_symbol_reader ()
+{
+  struct msym_bunch *next;
+
+  while (msym_bunch != NULL)
+    {
+      next = msym_bunch->next;
+      xfree (msym_bunch);
+      msym_bunch = next;
+    }
+}
+
 /* See minsyms.h.  */
 
 void
@@ -1087,37 +1106,6 @@ compare_minimal_symbols (const void *fn1p, const void *fn2p)
     }
 }
 
-/* Discard the currently collected minimal symbols, if any.  If we wish
-   to save them for later use, we must have already copied them somewhere
-   else before calling this function.
-
-   FIXME:  We could allocate the minimal symbol bunches on their own
-   obstack and then simply blow the obstack away when we are done with
-   it.  Is it worth the extra trouble though?  */
-
-static void
-do_discard_minimal_symbols_cleanup (void *arg)
-{
-  struct msym_bunch *next;
-
-  while (msym_bunch != NULL)
-    {
-      next = msym_bunch->next;
-      xfree (msym_bunch);
-      msym_bunch = next;
-    }
-}
-
-/* See minsyms.h.  */
-
-struct cleanup *
-make_cleanup_discard_minimal_symbols (void)
-{
-  return make_cleanup (do_discard_minimal_symbols_cleanup, 0);
-}
-
-
-
 /* Compact duplicate entries out of a minimal symbol table by walking
    through the table and compacting out entries with duplicate addresses
    and matching names.  Return the number of entries remaining.
@@ -1244,7 +1232,7 @@ build_minimal_symbol_hash_tables (struct objfile *objfile)
    attempts to demangle them if we later add more minimal symbols.  */
 
 void
-install_minimal_symbols (struct objfile *objfile)
+minimal_symbol_reader::install (struct objfile *objfile)
 {
   int bindex;
   int mcount;
diff --git a/gdb/minsyms.h b/gdb/minsyms.h
index 8857f1a..d75bd41 100644
--- a/gdb/minsyms.h
+++ b/gdb/minsyms.h
@@ -53,21 +53,33 @@ struct bound_minimal_symbol
    as opaque and use functions provided by minsyms.c to inspect them.
 */
 
-/* Prepare to start collecting minimal symbols.  This should be called
-   by a symbol reader to initialize the minimal symbol module.
-   Currently, minimal symbol table creation is not reentrant; it
-   relies on global (static) variables in minsyms.c.  */
+/* An RAII-based object that is used to record minimal symbols while
+   they are being read.  */
+class minimal_symbol_reader
+{
+ public:
+
+  /* Prepare to start collecting minimal symbols.  This should be called
+     by a symbol reader to initialize the minimal symbol module.
+     Currently, minimal symbol table creation is not reentrant; it
+     relies on global (static) variables in minsyms.c.  */
+
+  explicit minimal_symbol_reader ();
+
+  ~minimal_symbol_reader ();
 
-void init_minimal_symbol_collection (void);
+  /* Install the minimal symbols that have been collected into the
+     given objfile.  */
 
-/* Return a cleanup which is used to clean up the global state left
-   over by minimal symbol creation.  After calling
-   init_minimal_symbol_collection, a symbol reader should call this
-   function.  Then, after all minimal symbols have been read,
-   regardless of whether they are installed or not, the cleanup
-   returned by this function should be run.  */
+  void install (struct objfile *);
 
-struct cleanup *make_cleanup_discard_minimal_symbols (void);
+ private:
+
+  /* No need for these.  They are intentionally not defined anywhere.  */
+  minimal_symbol_reader &operator=
+    (const minimal_symbol_reader &);
+  minimal_symbol_reader (const minimal_symbol_reader &);
+};
 
 /* Record a new minimal symbol.  This is the "full" entry point;
    simpler convenience entry points are also provided below.
@@ -122,13 +134,6 @@ struct minimal_symbol *prim_record_minimal_symbol_and_info
      int section,
      struct objfile *);
 
-/* Install the minimal symbols that have been collected into the given
-   objfile.  After this is called, the cleanup returned by
-   make_cleanup_discard_minimal_symbols should be run in order to
-   clean up global state.  */
-
-void install_minimal_symbols (struct objfile *);
-
 /* Create the terminating entry of OBJFILE's minimal symbol table.
    If OBJFILE->msymbols is zero, allocate a single entry from
    OBJFILE->objfile_obstack; otherwise, just initialize
diff --git a/gdb/mipsread.c b/gdb/mipsread.c
index 27a59d2..dff1cb1 100644
--- a/gdb/mipsread.c
+++ b/gdb/mipsread.c
@@ -69,10 +69,8 @@ static void
 mipscoff_symfile_read (struct objfile *objfile, int symfile_flags)
 {
   bfd *abfd = objfile->obfd;
-  struct cleanup *back_to;
 
-  init_minimal_symbol_collection ();
-  back_to = make_cleanup_discard_minimal_symbols ();
+  minimal_symbol_reader reader;
 
   /* Now that the executable file is positioned at symbol table,
      process it and define symbols accordingly.  */
@@ -91,8 +89,7 @@ mipscoff_symfile_read (struct objfile *objfile, int symfile_flags)
   /* Install any minimal symbols that have been collected as the current
      minimal symbols for this objfile.  */
 
-  install_minimal_symbols (objfile);
-  do_cleanups (back_to);
+  reader.install (objfile);
 }
 
 /* Perform any local cleanups required when we are done with a
diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c
index 9ceefa0..3c843a0 100644
--- a/gdb/xcoffread.c
+++ b/gdb/xcoffread.c
@@ -3006,8 +3006,7 @@ xcoff_initial_scan (struct objfile *objfile, int symfile_flags)
   free_pending_blocks ();
   back_to = make_cleanup (really_free_pendings, 0);
 
-  init_minimal_symbol_collection ();
-  make_cleanup_discard_minimal_symbols ();
+  minimal_symbol_reader reader;
 
   /* Now that the symbol table data of the executable file are all in core,
      process them and define symbols accordingly.  */
@@ -3017,7 +3016,7 @@ xcoff_initial_scan (struct objfile *objfile, int symfile_flags)
   /* Install any minimal symbols that have been collected as the current
      minimal symbols for this objfile.  */
 
-  install_minimal_symbols (objfile);
+  reader.install (objfile);
 
   /* DWARF2 sections.  */