Patchwork [RFA,2/6] Allocate abbrev_table with new

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Submitter Tom Tromey
Date Jan. 6, 2018, 12:26 a.m.
Message ID <20180106002621.21099-3-tom@tromey.com>
Download mbox | patch
Permalink /patch/25243/
State New
Headers show

Comments

Tom Tromey - Jan. 6, 2018, 12:26 a.m.
This changes dwarf2read.c to allocate abbrev tables using "new", and
then updates the users.

This is somewhat complicated because ownership rules for abbrev tables
are obscure and involve a more than usual amount of cleanup
manipulation.

2018-01-05  Tom Tromey  <tom@tromey.com>

	* dwarf2read.c (class auto_free_abbrev_table): New.
	(struct abbrev_table): Add constructor, destructor.
	<alloc_abbrev, add_abbrev, lookup_abbrev>: Declare methods.
	(read_cutu_die_from_dwo): Add abbrev_table parameter.
	(init_cutu_and_read_dies): Update.
	(init_cutu_and_read_dies_no_follow): Use auto_free_abbrev_table.
	(build_type_psymtabs_1, peek_die_abbrev, read_full_die_1):
	Update.
	(abbrev_table::alloc_abbrev): Rename from
	abbrev_table_alloc_abbrev.
	(abbrev_table::add_abbrev): Rename from abbrev_table_add_abbrev.
	(abbrev_table::lookup_abbrev): Rename from
	abbrev_table_lookup_abbrev.
	(abbrev_table_read_table): Return a unique_ptr.
	(abbrev_table_free, abbrev_table_free_cleanup): Remove.
	(dwarf2_read_abbrevs): Update.
	(dwarf2_free_abbrev_table): Change argument type to dwarf2_cu*.
---
 gdb/ChangeLog    |  20 ++++++
 gdb/dwarf2read.c | 190 +++++++++++++++++++++++++++----------------------------
 2 files changed, 112 insertions(+), 98 deletions(-)

Patch

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5ad43d963a..339a4e728a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,25 @@ 
 2018-01-05  Tom Tromey  <tom@tromey.com>
 
+	* dwarf2read.c (class auto_free_abbrev_table): New.
+	(struct abbrev_table): Add constructor, destructor.
+	<alloc_abbrev, add_abbrev, lookup_abbrev>: Declare methods.
+	(read_cutu_die_from_dwo): Add abbrev_table parameter.
+	(init_cutu_and_read_dies): Update.
+	(init_cutu_and_read_dies_no_follow): Use auto_free_abbrev_table.
+	(build_type_psymtabs_1, peek_die_abbrev, read_full_die_1):
+	Update.
+	(abbrev_table::alloc_abbrev): Rename from
+	abbrev_table_alloc_abbrev.
+	(abbrev_table::add_abbrev): Rename from abbrev_table_add_abbrev.
+	(abbrev_table::lookup_abbrev): Rename from
+	abbrev_table_lookup_abbrev.
+	(abbrev_table_read_table): Return a unique_ptr.
+	(abbrev_table_free, abbrev_table_free_cleanup): Remove.
+	(dwarf2_read_abbrevs): Update.
+	(dwarf2_free_abbrev_table): Change argument type to dwarf2_cu*.
+
+2018-01-05  Tom Tromey  <tom@tromey.com>
+
 	* dwarf2read.c (dwarf2_compute_name): Update comment.
 	(read_func_scope, read_variable): Update.
 	(new_symbol): Remove.
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 92c4903241..7fd68c54fa 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -774,6 +774,28 @@  struct dwarf2_cu
   unsigned int processing_has_namespace_info : 1;
 };
 
+static void dwarf2_free_abbrev_table (struct dwarf2_cu *);
+
+/* Free an abbrev table on destruction.  */
+
+class auto_free_abbrev_table
+{
+public:
+  auto_free_abbrev_table (struct dwarf2_cu *cu)
+    : m_cu (cu)
+  {
+  }
+
+  ~auto_free_abbrev_table ()
+  {
+    dwarf2_free_abbrev_table (m_cu);
+  }
+
+private:
+
+  struct dwarf2_cu *m_cu;
+};
+
 /* Persistent data held for a compilation unit, even when not
    processing it.  We put a pointer to this structure in the
    read_symtab_private field of the psymtab.  */
@@ -1497,12 +1519,35 @@  struct attr_abbrev
 
 struct abbrev_table
 {
+  abbrev_table (sect_offset off)
+    : sect_off (off)
+  {
+    abbrevs =
+      XOBNEWVEC (&abbrev_obstack, struct abbrev_info *, ABBREV_HASH_SIZE);
+    memset (abbrevs, 0, ABBREV_HASH_SIZE * sizeof (struct abbrev_info *));
+  }
+
+  DISABLE_COPY_AND_ASSIGN (abbrev_table);
+
+  /* Allocate space for a struct abbrev_info object in
+     ABBREV_TABLE.  */
+  struct abbrev_info *alloc_abbrev ();
+
+  /* Add an abbreviation to the table.  */
+  void add_abbrev (unsigned int abbrev_number, struct abbrev_info *abbrev);
+
+  /* Look up an abbrev in the table.
+     Returns NULL if the abbrev is not found.  */
+
+  struct abbrev_info *lookup_abbrev (unsigned int abbrev_number);
+
+
   /* Where the abbrev table came from.
      This is used as a sanity check when the table is used.  */
   sect_offset sect_off;
 
   /* Storage for the abbrev table.  */
-  struct obstack abbrev_obstack;
+  auto_obstack abbrev_obstack;
 
   /* Hash table of abbrevs.
      This is an array of size ABBREV_HASH_SIZE allocated in abbrev_obstack.
@@ -1739,21 +1784,12 @@  static void dwarf2_read_symtab (struct partial_symtab *,
 
 static void psymtab_to_symtab_1 (struct partial_symtab *);
 
-static struct abbrev_info *abbrev_table_lookup_abbrev
-  (const struct abbrev_table *, unsigned int);
-
-static struct abbrev_table *abbrev_table_read_table
+static std::unique_ptr<struct abbrev_table> abbrev_table_read_table
   (struct dwarf2_section_info *, sect_offset);
 
-static void abbrev_table_free (struct abbrev_table *);
-
-static void abbrev_table_free_cleanup (void *);
-
 static void dwarf2_read_abbrevs (struct dwarf2_cu *,
 				 struct dwarf2_section_info *);
 
-static void dwarf2_free_abbrev_table (void *);
-
 static unsigned int peek_abbrev_code (bfd *, const gdb_byte *);
 
 static struct partial_die_info *load_partial_dies
@@ -7368,6 +7404,7 @@  init_cu_die_reader (struct die_reader_specs *reader,
    are filled in with the info of the DIE from the DWO file.
    ABBREV_TABLE_PROVIDED is non-zero if the caller of init_cutu_and_read_dies
    provided an abbrev table to use.
+   *ABBREV_TABLE may be filled in with a new abbrev table.
    The result is non-zero if a valid (non-dummy) DIE was found.  */
 
 static int
@@ -7379,7 +7416,8 @@  read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
 			struct die_reader_specs *result_reader,
 			const gdb_byte **result_info_ptr,
 			struct die_info **result_comp_unit_die,
-			int *result_has_children)
+			int *result_has_children,
+			gdb::optional<auto_free_abbrev_table> *abbrev_table)
 {
   struct objfile *objfile = dwarf2_per_objfile->objfile;
   struct dwarf2_cu *cu = this_cu->cu;
@@ -7501,7 +7539,7 @@  read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
 	 init_cutu_and_read_dies owns it.  */
       dwarf2_read_abbrevs (cu, dwo_abbrev_section);
       /* Ensure the DWO abbrev table gets freed.  */
-      make_cleanup (dwarf2_free_abbrev_table, cu);
+      abbrev_table->emplace (cu);
     }
   else
     {
@@ -7661,12 +7699,14 @@  init_tu_and_read_dwo_dies (struct dwarf2_per_cu_data *this_cu,
      abbrev table.  When reading DWOs with skeletonless TUs, all the TUs
      could share abbrev tables.  */
 
+  gdb::optional<auto_free_abbrev_table> abbrev_table;
   if (read_cutu_die_from_dwo (this_cu, sig_type->dwo_unit,
 			      0 /* abbrev_table_provided */,
 			      NULL /* stub_comp_unit_die */,
 			      sig_type->dwo_unit->dwo_file->comp_dir,
 			      &reader, &info_ptr,
-			      &comp_unit_die, &has_children) == 0)
+			      &comp_unit_die, &has_children,
+			      &abbrev_table) == 0)
     {
       /* Dummy die.  */
       do_cleanups (cleanups);
@@ -7688,10 +7728,6 @@  init_tu_and_read_dwo_dies (struct dwarf2_per_cu_data *this_cu,
 	     caller clean it up when finished with it.  */
 	  discard_cleanups (free_cu_cleanup);
 
-	  /* We can only discard free_cu_cleanup and all subsequent cleanups.
-	     So we have to manually free the abbrev table.  */
-	  dwarf2_free_abbrev_table (cu);
-
 	  /* Link this CU into read_in_chain.  */
 	  this_cu->cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
 	  dwarf2_per_objfile->read_in_chain = this_cu;
@@ -7852,6 +7888,7 @@  init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
      done.  Note that it's important that if the CU had an abbrev table
      on entry we don't free it when we're done: Somewhere up the call stack
      it may be in use.  */
+  gdb::optional<auto_free_abbrev_table> abbrev_table_freer;
   if (abbrev_table != NULL)
     {
       gdb_assert (cu->abbrev_table == NULL);
@@ -7861,7 +7898,7 @@  init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
   else if (cu->abbrev_table == NULL)
     {
       dwarf2_read_abbrevs (cu, abbrev_section);
-      make_cleanup (dwarf2_free_abbrev_table, cu);
+      abbrev_table_freer.emplace (cu);
     }
   else if (rereading_dwo_cu)
     {
@@ -7878,6 +7915,7 @@  init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
      Note that if USE_EXISTING_OK != 0, and THIS_CU->cu already contains a
      DWO CU, that this test will fail (the attribute will not be present).  */
   attr = dwarf2_attr (comp_unit_die, DW_AT_GNU_dwo_name, cu);
+  gdb::optional<auto_free_abbrev_table> abbrev_table_freer_2;
   if (attr)
     {
       struct dwo_unit *dwo_unit;
@@ -7897,7 +7935,8 @@  init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
 				      abbrev_table != NULL,
 				      comp_unit_die, NULL,
 				      &reader, &info_ptr,
-				      &dwo_comp_unit_die, &has_children) == 0)
+				      &dwo_comp_unit_die, &has_children,
+				      &abbrev_table_freer_2) == 0)
 	    {
 	      /* Dummy die.  */
 	      do_cleanups (cleanups);
@@ -7927,10 +7966,6 @@  init_cutu_and_read_dies (struct dwarf2_per_cu_data *this_cu,
 	     caller clean it up when finished with it.  */
 	  discard_cleanups (free_cu_cleanup);
 
-	  /* We can only discard free_cu_cleanup and all subsequent cleanups.
-	     So we have to manually free the abbrev table.  */
-	  dwarf2_free_abbrev_table (cu);
-
 	  /* Link this CU into read_in_chain.  */
 	  this_cu->cu->read_in_chain = dwarf2_per_objfile->read_in_chain;
 	  dwarf2_per_objfile->read_in_chain = this_cu;
@@ -8011,7 +8046,7 @@  init_cutu_and_read_dies_no_follow (struct dwarf2_per_cu_data *this_cu,
     }
 
   dwarf2_read_abbrevs (&cu, abbrev_section);
-  make_cleanup (dwarf2_free_abbrev_table, &cu);
+  auto_free_abbrev_table abbrev_table_freer (&cu);
 
   init_cu_die_reader (&reader, &cu, section, dwo_file);
   info_ptr = read_full_die (&reader, &comp_unit_die, info_ptr, &has_children);
@@ -8483,7 +8518,7 @@  build_type_psymtabs_1 (void)
 {
   struct tu_stats *tu_stats = &dwarf2_per_objfile->tu_stats;
   struct cleanup *cleanups;
-  struct abbrev_table *abbrev_table;
+  std::unique_ptr<struct abbrev_table> abbrev_table;
   sect_offset abbrev_offset;
   struct tu_abbrev_offset *sorted_by_abbrev;
   int i;
@@ -8534,8 +8569,6 @@  build_type_psymtabs_1 (void)
 	 sizeof (struct tu_abbrev_offset), sort_tu_by_abbrev_offset);
 
   abbrev_offset = (sect_offset) ~(unsigned) 0;
-  abbrev_table = NULL;
-  make_cleanup (abbrev_table_free_cleanup, &abbrev_table);
 
   for (i = 0; i < dwarf2_per_objfile->n_type_units; ++i)
     {
@@ -8545,13 +8578,6 @@  build_type_psymtabs_1 (void)
       if (abbrev_table == NULL
 	  || tu->abbrev_offset != abbrev_offset)
 	{
-	  if (abbrev_table != NULL)
-	    {
-	      abbrev_table_free (abbrev_table);
-	      /* Reset to NULL in case abbrev_table_read_table throws
-		 an error: abbrev_table_free_cleanup will get called.  */
-	      abbrev_table = NULL;
-	    }
 	  abbrev_offset = tu->abbrev_offset;
 	  abbrev_table =
 	    abbrev_table_read_table (&dwarf2_per_objfile->abbrev,
@@ -8559,8 +8585,8 @@  build_type_psymtabs_1 (void)
 	  ++tu_stats->nr_uniq_abbrev_tables;
 	}
 
-      init_cutu_and_read_dies (&tu->sig_type->per_cu, abbrev_table, 0, 0,
-			       build_type_psymtabs_reader, NULL);
+      init_cutu_and_read_dies (&tu->sig_type->per_cu, abbrev_table.get (),
+			       0, 0, build_type_psymtabs_reader, NULL);
     }
 
   do_cleanups (cleanups);
@@ -9514,7 +9540,7 @@  peek_die_abbrev (const gdb_byte *info_ptr, unsigned int *bytes_read,
   if (abbrev_number == 0)
     return NULL;
 
-  abbrev = abbrev_table_lookup_abbrev (cu->abbrev_table, abbrev_number);
+  abbrev = cu->abbrev_table->lookup_abbrev (abbrev_number);
   if (!abbrev)
     {
       error (_("Dwarf Error: Could not find abbrev number %d in %s"
@@ -17851,7 +17877,7 @@  read_full_die_1 (const struct die_reader_specs *reader,
       return info_ptr;
     }
 
-  abbrev = abbrev_table_lookup_abbrev (cu->abbrev_table, abbrev_number);
+  abbrev = cu->abbrev_table->lookup_abbrev (abbrev_number);
   if (!abbrev)
     error (_("Dwarf Error: could not find abbrev number %d [in module %s]"),
 	   abbrev_number,
@@ -17912,12 +17938,12 @@  read_full_die (const struct die_reader_specs *reader,
 
 /* Allocate space for a struct abbrev_info object in ABBREV_TABLE.  */
 
-static struct abbrev_info *
-abbrev_table_alloc_abbrev (struct abbrev_table *abbrev_table)
+struct abbrev_info *
+abbrev_table::alloc_abbrev ()
 {
   struct abbrev_info *abbrev;
 
-  abbrev = XOBNEW (&abbrev_table->abbrev_obstack, struct abbrev_info);
+  abbrev = XOBNEW (&abbrev_obstack, struct abbrev_info);
   memset (abbrev, 0, sizeof (struct abbrev_info));
 
   return abbrev;
@@ -17925,30 +17951,28 @@  abbrev_table_alloc_abbrev (struct abbrev_table *abbrev_table)
 
 /* Add an abbreviation to the table.  */
 
-static void
-abbrev_table_add_abbrev (struct abbrev_table *abbrev_table,
-			 unsigned int abbrev_number,
-			 struct abbrev_info *abbrev)
+void
+abbrev_table::add_abbrev (unsigned int abbrev_number,
+			  struct abbrev_info *abbrev)
 {
   unsigned int hash_number;
 
   hash_number = abbrev_number % ABBREV_HASH_SIZE;
-  abbrev->next = abbrev_table->abbrevs[hash_number];
-  abbrev_table->abbrevs[hash_number] = abbrev;
+  abbrev->next = abbrevs[hash_number];
+  abbrevs[hash_number] = abbrev;
 }
 
 /* Look up an abbrev in the table.
    Returns NULL if the abbrev is not found.  */
 
-static struct abbrev_info *
-abbrev_table_lookup_abbrev (const struct abbrev_table *abbrev_table,
-			    unsigned int abbrev_number)
+struct abbrev_info *
+abbrev_table::lookup_abbrev (unsigned int abbrev_number)
 {
   unsigned int hash_number;
   struct abbrev_info *abbrev;
 
   hash_number = abbrev_number % ABBREV_HASH_SIZE;
-  abbrev = abbrev_table->abbrevs[hash_number];
+  abbrev = abbrevs[hash_number];
 
   while (abbrev)
     {
@@ -17961,13 +17985,12 @@  abbrev_table_lookup_abbrev (const struct abbrev_table *abbrev_table,
 
 /* Read in an abbrev table.  */
 
-static struct abbrev_table *
+static std::unique_ptr<struct abbrev_table>
 abbrev_table_read_table (struct dwarf2_section_info *section,
 			 sect_offset sect_off)
 {
   struct objfile *objfile = dwarf2_per_objfile->objfile;
   bfd *abfd = get_section_bfd_owner (section);
-  struct abbrev_table *abbrev_table;
   const gdb_byte *abbrev_ptr;
   struct abbrev_info *cur_abbrev;
   unsigned int abbrev_number, bytes_read, abbrev_name;
@@ -17975,14 +17998,8 @@  abbrev_table_read_table (struct dwarf2_section_info *section,
   struct attr_abbrev *cur_attrs;
   unsigned int allocated_attrs;
 
-  abbrev_table = XNEW (struct abbrev_table);
-  abbrev_table->sect_off = sect_off;
-  obstack_init (&abbrev_table->abbrev_obstack);
-  abbrev_table->abbrevs =
-    XOBNEWVEC (&abbrev_table->abbrev_obstack, struct abbrev_info *,
-	       ABBREV_HASH_SIZE);
-  memset (abbrev_table->abbrevs, 0,
-	  ABBREV_HASH_SIZE * sizeof (struct abbrev_info *));
+  std::unique_ptr<struct abbrev_table> abbrev_table
+    (new struct abbrev_table (sect_off));
 
   dwarf2_read_section (objfile, section);
   abbrev_ptr = section->buffer + to_underlying (sect_off);
@@ -17995,7 +18012,7 @@  abbrev_table_read_table (struct dwarf2_section_info *section,
   /* Loop until we reach an abbrev number of 0.  */
   while (abbrev_number)
     {
-      cur_abbrev = abbrev_table_alloc_abbrev (abbrev_table);
+      cur_abbrev = abbrev_table->alloc_abbrev ();
 
       /* read in abbrev header */
       cur_abbrev->number = abbrev_number;
@@ -18050,7 +18067,7 @@  abbrev_table_read_table (struct dwarf2_section_info *section,
       memcpy (cur_abbrev->attrs, cur_attrs,
 	      cur_abbrev->num_attrs * sizeof (struct attr_abbrev));
 
-      abbrev_table_add_abbrev (abbrev_table, abbrev_number, cur_abbrev);
+      abbrev_table->add_abbrev (abbrev_number, cur_abbrev);
 
       /* Get next abbreviation.
          Under Irix6 the abbreviations for a compilation unit are not
@@ -18063,7 +18080,7 @@  abbrev_table_read_table (struct dwarf2_section_info *section,
 	break;
       abbrev_number = read_unsigned_leb128 (abfd, abbrev_ptr, &bytes_read);
       abbrev_ptr += bytes_read;
-      if (abbrev_table_lookup_abbrev (abbrev_table, abbrev_number) != NULL)
+      if (abbrev_table->lookup_abbrev (abbrev_number) != NULL)
 	break;
     }
 
@@ -18071,52 +18088,29 @@  abbrev_table_read_table (struct dwarf2_section_info *section,
   return abbrev_table;
 }
 
-/* Free the resources held by ABBREV_TABLE.  */
-
-static void
-abbrev_table_free (struct abbrev_table *abbrev_table)
-{
-  obstack_free (&abbrev_table->abbrev_obstack, NULL);
-  xfree (abbrev_table);
-}
-
-/* Same as abbrev_table_free but as a cleanup.
-   We pass in a pointer to the pointer to the table so that we can
-   set the pointer to NULL when we're done.  It also simplifies
-   build_type_psymtabs_1.  */
-
-static void
-abbrev_table_free_cleanup (void *table_ptr)
-{
-  struct abbrev_table **abbrev_table_ptr = (struct abbrev_table **) table_ptr;
-
-  if (*abbrev_table_ptr != NULL)
-    abbrev_table_free (*abbrev_table_ptr);
-  *abbrev_table_ptr = NULL;
-}
-
 /* Read the abbrev table for CU from ABBREV_SECTION.  */
 
 static void
 dwarf2_read_abbrevs (struct dwarf2_cu *cu,
 		     struct dwarf2_section_info *abbrev_section)
 {
-  cu->abbrev_table =
-    abbrev_table_read_table (abbrev_section, cu->header.abbrev_sect_off);
+  cu->abbrev_table
+    = (abbrev_table_read_table (abbrev_section, cu->header.abbrev_sect_off)
+       .release ());
 }
 
 /* Release the memory used by the abbrev table for a compilation unit.  */
 
 static void
-dwarf2_free_abbrev_table (void *ptr_to_cu)
+dwarf2_free_abbrev_table (struct dwarf2_cu *cu)
 {
-  struct dwarf2_cu *cu = (struct dwarf2_cu *) ptr_to_cu;
-
   if (cu->abbrev_table != NULL)
-    abbrev_table_free (cu->abbrev_table);
-  /* Set this to NULL so that we SEGV if we try to read it later,
-     and also because free_comp_unit verifies this is NULL.  */
-  cu->abbrev_table = NULL;
+    {
+      delete cu->abbrev_table;
+      /* Set this to NULL so that we SEGV if we try to read it later,
+	 and also because free_comp_unit verifies this is NULL.  */
+      cu->abbrev_table = NULL;
+    }
 }
 
 /* Returns nonzero if TAG represents a type that we might generate a partial