objfile_per_bfd_storage non-POD

A following patch will want to add a std::vector to
objfile_per_bfd_storage.  That makes it non-trivially
constructible/destructible.  Since objfile_per_bfd_storage objects are
allocated on an obstack, we need to call their ctors/dtors manually.
This is what this patch does.  And then since we can now rely on
ctors/dtors being run, make objfile_per_bfd_storage::storage_obstack
be an auto_obstack.

gdb/ChangeLog:
2017-06-27  Pedro Alves  <palves@redhat.com>

	* objfiles.c (get_objfile_bfd_data): Call bfd_alloc instead of
	bfd_zalloc.  Call objfile_per_bfd_storage's ctor.
	(free_objfile_per_bfd_storage): Call objfile_per_bfd_storage's
	dtor.
	* objfiles.h (objfile_per_bfd_storage): Add ctor.  Make
	'storage_obstack' field an auto_obstack.  In-class initialize all
	non-bitfield fields.  Make minsyms_read bool.
	* symfile.c (read_symbols): Adjust.

4 files changed, 41 insertions, 19 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1534468..c455d41 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,14 @@
+2017-06-27  Pedro Alves  <palves@redhat.com>
+
+	* objfiles.c (get_objfile_bfd_data): Call bfd_alloc instead of
+	bfd_zalloc.  Call objfile_per_bfd_storage's ctor.
+	(free_objfile_per_bfd_storage): Call objfile_per_bfd_storage's
+	dtor.
+	* objfiles.h (objfile_per_bfd_storage): Add ctor.  Make
+	'storage_obstack' field an auto_obstack.  In-class initialize all
+	non-bitfield fields.  Make minsyms_read bool.
+	* symfile.c (read_symbols): Adjust.
+
 2017-06-27  Alan Hayward  <alan.hayward@arm.com>
 
 	* remote-sim.c (gdbsim_fetch_register): Use byte_vector.
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index 9500b1c..d261c87 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -142,12 +142,19 @@ get_objfile_bfd_data (struct objfile *objfile, struct bfd *abfd)
 	{
 	  storage
 	    = ((struct objfile_per_bfd_storage *)
-	       bfd_zalloc (abfd, sizeof (struct objfile_per_bfd_storage)));
+	       bfd_alloc (abfd, sizeof (struct objfile_per_bfd_storage)));
 	  set_bfd_data (abfd, objfiles_bfd_data, storage);
 	}
       else
-	storage = OBSTACK_ZALLOC (&objfile->objfile_obstack,
-				  struct objfile_per_bfd_storage);
+	{
+	  storage = (objfile_per_bfd_storage *)
+	    obstack_alloc (&objfile->objfile_obstack,
+			   sizeof (objfile_per_bfd_storage));
+	}
+
+      /* objfile_per_bfd_storage is not trivially constructible, must
+	 call the ctor manually.  */
+      storage = new (storage) objfile_per_bfd_storage ();
 
       /* Look up the gdbarch associated with the BFD.  */
       if (abfd != NULL)
@@ -171,7 +178,7 @@ free_objfile_per_bfd_storage (struct objfile_per_bfd_storage *storage)
   bcache_xfree (storage->macro_cache);
   if (storage->demangled_names_hash)
     htab_delete (storage->demangled_names_hash);
-  obstack_free (&storage->storage_obstack, 0);
+  storage->~objfile_per_bfd_storage ();
 }
 
 /* A wrapper for free_objfile_per_bfd_storage that can be passed as a
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 58db6c9..3260425 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -184,24 +184,28 @@ extern void print_symbol_bcache_statistics (void);
 
 struct objfile_per_bfd_storage
 {
+  objfile_per_bfd_storage ()
+    : minsyms_read (false)
+  {}
+
   /* The storage has an obstack of its own.  */
 
-  struct obstack storage_obstack;
+  auto_obstack storage_obstack;
 
   /* Byte cache for file names.  */
 
-  struct bcache *filename_cache;
+  bcache *filename_cache = NULL;
 
   /* Byte cache for macros.  */
 
-  struct bcache *macro_cache;
+  bcache *macro_cache = NULL;
 
   /* The gdbarch associated with the BFD.  Note that this gdbarch is
      determined solely from BFD information, without looking at target
      information.  The gdbarch determined from a running target may
      differ from this e.g. with respect to register types and names.  */
 
-  struct gdbarch *gdbarch;
+  struct gdbarch *gdbarch = NULL;
 
   /* Hash table for mapping symbol names to demangled names.  Each
      entry in the hash table is actually two consecutive strings,
@@ -209,19 +213,19 @@ struct objfile_per_bfd_storage
      name, and the second is the demangled name or just a zero byte
      if the name doesn't demangle.  */
 
-  struct htab *demangled_names_hash;
+  htab *demangled_names_hash = NULL;
 
   /* The per-objfile information about the entry point, the scope (file/func)
      containing the entry point, and the scope of the user's main() func.  */
 
-  struct entry_info ei;
+  entry_info ei {};
 
   /* The name and language of any "main" found in this objfile.  The
      name can be NULL, which means that the information was not
      recorded.  */
 
-  const char *name_of_main;
-  enum language language_of_main;
+  const char *name_of_main = NULL;
+  enum language language_of_main = language_unknown;
 
   /* Each file contains a pointer to an array of minimal symbols for all
      global symbols that are defined within the file.  The array is
@@ -233,15 +237,15 @@ struct objfile_per_bfd_storage
      as all the data that it points to, should be allocated on the
      objfile_obstack for this file.  */
 
-  struct minimal_symbol *msymbols;
-  int minimal_symbol_count;
+  minimal_symbol *msymbols = NULL;
+  int minimal_symbol_count = 0;
 
   /* The number of minimal symbols read, before any minimal symbol
      de-duplication is applied.  Note in particular that this has only
      a passing relationship with the actual size of the table above;
      use minimal_symbol_count if you need the true size.  */
 
-  int n_minsyms;
+  int n_minsyms = 0;
 
   /* This is true if minimal symbols have already been read.  Symbol
      readers can use this to bypass minimal symbol reading.  Also, the
@@ -251,16 +255,16 @@ struct objfile_per_bfd_storage
      for multiple readers to install minimal symbols into a given
      per-BFD.  */
 
-  unsigned int minsyms_read : 1;
+  bool minsyms_read : 1;
 
   /* This is a hash table used to index the minimal symbols by name.  */
 
-  struct minimal_symbol *msymbol_hash[MINIMAL_SYMBOL_HASH_SIZE];
+  minimal_symbol *msymbol_hash[MINIMAL_SYMBOL_HASH_SIZE] {};
 
   /* This hash table is used to index the minimal symbols by their
      demangled names.  */
 
-  struct minimal_symbol *msymbol_demangled_hash[MINIMAL_SYMBOL_HASH_SIZE];
+  minimal_symbol *msymbol_demangled_hash[MINIMAL_SYMBOL_HASH_SIZE] {};
 };
 
 /* Master structure for keeping track of each file from which
diff --git a/gdb/symfile.c b/gdb/symfile.c
index f936cf3..aa53415 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -859,7 +859,7 @@ static void
 read_symbols (struct objfile *objfile, symfile_add_flags add_flags)
 {
   (*objfile->sf->sym_read) (objfile, add_flags);
-  objfile->per_bfd->minsyms_read = 1;
+  objfile->per_bfd->minsyms_read = true;
 
   /* find_separate_debug_file_in_section should be called only if there is
      single binary with no existing separate debug info file.  */