[binutils-gdb] Do not separately read type units

[binutils-gdb] Do not separately read type units

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b8efb248a88cb9c6760b44b5f7cfa4cb1b8dc004

commit b8efb248a88cb9c6760b44b5f7cfa4cb1b8dc004
Author: Tom Tromey <tom@tromey.com>
Date:   Fri Apr 30 14:07:58 2021 -0600

    Do not separately read type units
    
    Currently, the DWARF reader has a separate pass to read type units --
    create_all_type_units.  While working on other patches, I discovered
    that this caused DWARF 5 type units to be read twice, once by
    create_all_comp_units and once by create_all_type_units.
    
    There's no need any more (if there ever was) to treat type units
    differently from CUs.  So, this patch removes create_all_type_units
    and unifies the code paths.
    
    Note that the DWO code still has a second pass.  I haven't looked into
    this code yet; perhaps it can also be simplified.
    
    Regression tested using the debug-types board file on x86-64 Fedora 32.
    
    gdb/ChangeLog
    2021-04-30  Tom Tromey  <tom@tromey.com>
    
            * dwarf2/read.c (dwarf2_initialize_objfile): Update.
            (add_signatured_type_cu_to_table): Remove.
            (create_debug_type_hash_table): Assume dwo_file is non-null.
            (create_debug_types_hash_table): Update comment.
            (create_all_type_units): Remove.
            (sort_tu_by_abbrev_offset): Update comment.
            (build_type_psymtabs): Rename from build_type_psymtabs_1.
            (build_type_psymtabs): Remove.
            (process_skeletonless_type_unit, dwarf2_build_psymtabs_hard):
            Update.
            (read_comp_units_from_section): Add types_htab, section_kind
            parameters.
            (create_all_comp_units): Read type units.

Diff:
---
 gdb/ChangeLog     |  16 +++++
 gdb/dwarf2/read.c | 186 ++++++++++++++++--------------------------------------
 2 files changed, 69 insertions(+), 133 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index fb82dbed51d..6ec6a701bfd 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,19 @@
+2021-04-30  Tom Tromey  <tom@tromey.com>
+
+	* dwarf2/read.c (dwarf2_initialize_objfile): Update.
+	(add_signatured_type_cu_to_table): Remove.
+	(create_debug_type_hash_table): Assume dwo_file is non-null.
+	(create_debug_types_hash_table): Update comment.
+	(create_all_type_units): Remove.
+	(sort_tu_by_abbrev_offset): Update comment.
+	(build_type_psymtabs): Rename from build_type_psymtabs_1.
+	(build_type_psymtabs): Remove.
+	(process_skeletonless_type_unit, dwarf2_build_psymtabs_hard):
+	Update.
+	(read_comp_units_from_section): Add types_htab, section_kind
+	parameters.
+	(create_all_comp_units): Read type units.
+
 2021-04-30  Tom Tromey  <tom@tromey.com>
 
 	* dwarf2/read.h (struct tu_stats) <nr_tus>: New member.
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index f3c413a8993..5796cf1730b 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -1689,8 +1689,6 @@ static struct type *set_die_type (struct die_info *, struct type *,
 
 static void create_all_comp_units (dwarf2_per_objfile *per_objfile);
 
-static int create_all_type_units (dwarf2_per_objfile *per_objfile);
-
 static void load_full_comp_unit (dwarf2_per_cu_data *per_cu,
 				 dwarf2_per_objfile *per_objfile,
 				 dwarf2_cu *existing_cu,
@@ -5656,7 +5654,6 @@ dwarf2_initialize_objfile (struct objfile *objfile)
 
       per_bfd->using_index = 1;
       create_all_comp_units (per_objfile);
-      create_all_type_units (per_objfile);
       per_bfd->quick_file_names_table
 	= create_quick_file_names_table (per_bfd->all_comp_units.size ());
       per_objfile->resize_symtabs ();
@@ -6002,20 +5999,6 @@ allocate_signatured_type_table ()
 				     NULL, xcalloc, xfree));
 }
 
-/* A helper function to add a signatured type CU to a table.  */
-
-static int
-add_signatured_type_cu_to_table (void **slot, void *datum)
-{
-  struct signatured_type *sigt = (struct signatured_type *) *slot;
-  std::vector<std::unique_ptr<dwarf2_per_cu_data>> *all_comp_units
-    = (std::vector<std::unique_ptr<dwarf2_per_cu_data>> *) datum;
-
-  all_comp_units->emplace_back (sigt);
-
-  return 1;
-}
-
 /* A helper for create_debug_types_hash_table.  Read types from SECTION
    and fill them into TYPES_HTAB.  It will process only type units,
    therefore DW_UT_type.  */
@@ -6031,9 +6014,7 @@ create_debug_type_hash_table (dwarf2_per_objfile *per_objfile,
   bfd *abfd;
   const gdb_byte *info_ptr, *end_ptr;
 
-  abbrev_section = (dwo_file != NULL
-		    ? &dwo_file->sections.abbrev
-		    : &per_objfile->per_bfd->abbrev);
+  abbrev_section = &dwo_file->sections.abbrev;
 
   dwarf_read_debug_printf ("Reading %s for %s",
 			   section->get_name (),
@@ -6087,68 +6068,25 @@ create_debug_type_hash_table (dwarf2_per_objfile *per_objfile,
 	}
 
       if (types_htab == NULL)
-	{
-	  if (dwo_file)
-	    types_htab = allocate_dwo_unit_table ();
-	  else
-	    types_htab = allocate_signatured_type_table ();
-	}
+	types_htab = allocate_dwo_unit_table ();
 
-      if (dwo_file)
-	{
-	  dwo_tu = OBSTACK_ZALLOC (&per_objfile->per_bfd->obstack, dwo_unit);
-	  dwo_tu->dwo_file = dwo_file;
-	  dwo_tu->signature = header.signature;
-	  dwo_tu->type_offset_in_tu = header.type_cu_offset_in_tu;
-	  dwo_tu->section = section;
-	  dwo_tu->sect_off = sect_off;
-	  dwo_tu->length = length;
-	}
-      else
-	{
-	  /* N.B.: type_offset is not usable if this type uses a DWO file.
-	     The real type_offset is in the DWO file.  */
-	  dwo_tu = NULL;
-	  sig_type = per_objfile->per_bfd->allocate_signatured_type ();
-	  sig_type->signature = header.signature;
-	  sig_type->type_offset_in_tu = header.type_cu_offset_in_tu;
-	  sig_type->is_debug_types = 1;
-	  sig_type->section = section;
-	  sig_type->sect_off = sect_off;
-	  sig_type->length = length;
-	}
-
-      slot = htab_find_slot (types_htab.get (),
-			     (dwo_file
-			      ? (void *) dwo_tu
-			      : (void *) sig_type.get ()),
-			     INSERT);
+      dwo_tu = OBSTACK_ZALLOC (&per_objfile->per_bfd->obstack, dwo_unit);
+      dwo_tu->dwo_file = dwo_file;
+      dwo_tu->signature = header.signature;
+      dwo_tu->type_offset_in_tu = header.type_cu_offset_in_tu;
+      dwo_tu->section = section;
+      dwo_tu->sect_off = sect_off;
+      dwo_tu->length = length;
+
+      slot = htab_find_slot (types_htab.get (), dwo_tu, INSERT);
       gdb_assert (slot != NULL);
       if (*slot != NULL)
-	{
-	  sect_offset dup_sect_off;
-
-	  if (dwo_file)
-	    {
-	      const struct dwo_unit *dup_tu
-		= (const struct dwo_unit *) *slot;
-
-	      dup_sect_off = dup_tu->sect_off;
-	    }
-	  else
-	    {
-	      const struct signatured_type *dup_tu
-		= (const struct signatured_type *) *slot;
-
-	      dup_sect_off = dup_tu->sect_off;
-	    }
-
-	  complaint (_("debug type entry at offset %s is duplicate to"
-		       " the entry at offset %s, signature %s"),
-		     sect_offset_str (sect_off), sect_offset_str (dup_sect_off),
-		     hex_string (header.signature));
-	}
-      *slot = dwo_file ? (void *) dwo_tu : (void *) sig_type.release ();
+	complaint (_("debug type entry at offset %s is duplicate to"
+		     " the entry at offset %s, signature %s"),
+		   sect_offset_str (sect_off),
+		   sect_offset_str (dwo_tu->sect_off),
+		   hex_string (header.signature));
+      *slot = dwo_tu;
 
       dwarf_read_debug_printf_v ("  offset %s, signature %s",
 				 sect_offset_str (sect_off),
@@ -6160,8 +6098,7 @@ create_debug_type_hash_table (dwarf2_per_objfile *per_objfile,
 
 /* Create the hash table of all entries in the .debug_types
    (or .debug_types.dwo) section(s).
-   If reading a DWO file, then DWO_FILE is a pointer to the DWO file object,
-   otherwise it is NULL.
+   DWO_FILE is a pointer to the DWO file object.
 
    The result is a pointer to the hash table or NULL if there are no types.
 
@@ -6178,35 +6115,6 @@ create_debug_types_hash_table (dwarf2_per_objfile *per_objfile,
 				  rcuh_kind::TYPE);
 }
 
-/* Create the hash table of all entries in the .debug_types section,
-   and update all_comp_units.
-   The result is zero if there is an error (e.g. missing .debug_types section),
-   otherwise non-zero.	*/
-
-static int
-create_all_type_units (dwarf2_per_objfile *per_objfile)
-{
-  htab_up types_htab;
-
-  create_debug_type_hash_table (per_objfile, NULL, &per_objfile->per_bfd->info,
-				types_htab, rcuh_kind::COMPILE);
-  create_debug_types_hash_table (per_objfile, NULL, per_objfile->per_bfd->types,
-				 types_htab);
-  if (types_htab == NULL)
-    {
-      per_objfile->per_bfd->signatured_types = NULL;
-      return 0;
-    }
-
-  per_objfile->per_bfd->signatured_types = std::move (types_htab);
-
-  htab_traverse_noresize (per_objfile->per_bfd->signatured_types.get (),
-			  add_signatured_type_cu_to_table,
-			  &per_objfile->per_bfd->all_comp_units);
-
-  return 1;
-}
-
 /* Add an entry for signature SIG to dwarf2_per_objfile->per_bfd->signatured_types.
    If SLOT is non-NULL, it is the entry to use in the hash table.
    Otherwise we find one.  */
@@ -7447,7 +7355,7 @@ struct tu_abbrev_offset
   sect_offset abbrev_offset;
 };
 
-/* Helper routine for build_type_psymtabs_1, passed to std::sort.  */
+/* Helper routine for build_type_psymtabs, passed to std::sort.  */
 
 static bool
 sort_tu_by_abbrev_offset (const struct tu_abbrev_offset &a,
@@ -7457,7 +7365,6 @@ sort_tu_by_abbrev_offset (const struct tu_abbrev_offset &a,
 }
 
 /* Efficiently read all the type units.
-   This does the bulk of the work for build_type_psymtabs.
 
    The efficiency is because we sort TUs by the abbrev table they use and
    only read each abbrev table once.  In one program there are 200K TUs
@@ -7475,7 +7382,7 @@ sort_tu_by_abbrev_offset (const struct tu_abbrev_offset &a,
    dwarf2_per_objfile->per_bfd->type_unit_groups.  */
 
 static void
-build_type_psymtabs_1 (dwarf2_per_objfile *per_objfile)
+build_type_psymtabs (dwarf2_per_objfile *per_objfile)
 {
   struct tu_stats *tu_stats = &per_objfile->per_bfd->tu_stats;
   abbrev_table_up abbrev_table;
@@ -7602,18 +7509,6 @@ build_type_psymtab_dependencies (void **slot, void *info)
   return 1;
 }
 
-/* Subroutine of dwarf2_build_psymtabs_hard to simplify it.
-   Build partial symbol tables for the .debug_types comp-units.  */
-
-static void
-build_type_psymtabs (dwarf2_per_objfile *per_objfile)
-{
-  if (! create_all_type_units (per_objfile))
-    return;
-
-  build_type_psymtabs_1 (per_objfile);
-}
-
 /* Traversal function for process_skeletonless_type_unit.
    Read a TU in a DWO file and build partial symbols for it.  */
 
@@ -7637,13 +7532,13 @@ process_skeletonless_type_unit (void **slot, void *info)
   if (*slot != NULL)
     return 1;
 
-  /* This does the job that create_all_type_units would have done for
+  /* This does the job that create_all_comp_units would have done for
      this TU.  */
   entry = add_type_unit (per_objfile, dwo_unit->signature, slot);
   fill_in_sig_entry_from_dwo_entry (per_objfile, entry, dwo_unit);
   *slot = entry;
 
-  /* This does the job that build_type_psymtabs_1 would have done.  */
+  /* This does the job that build_type_psymtabs would have done.  */
   cutu_reader reader (entry, per_objfile, nullptr, nullptr, false);
   if (!reader.dummy_p)
     build_type_psymtabs_reader (&reader, reader.info_ptr,
@@ -7725,9 +7620,8 @@ dwarf2_build_psymtabs_hard (dwarf2_per_objfile *per_objfile)
      read_in_chain.  Make sure to free them when we're done.  */
   free_cached_comp_units freer (per_objfile);
 
-  build_type_psymtabs (per_objfile);
-
   create_all_comp_units (per_objfile);
+  build_type_psymtabs (per_objfile);
 
   /* Create a temporary address map on a temporary obstack.  We later
      copy this to the final obstack.  */
@@ -7800,7 +7694,9 @@ static void
 read_comp_units_from_section (dwarf2_per_objfile *per_objfile,
 			      struct dwarf2_section_info *section,
 			      struct dwarf2_section_info *abbrev_section,
-			      unsigned int is_dwz)
+			      unsigned int is_dwz,
+			      htab_up &types_htab,
+			      rcuh_kind section_kind)
 {
   const gdb_byte *info_ptr;
   struct objfile *objfile = per_objfile->objfile;
@@ -7822,17 +7718,31 @@ read_comp_units_from_section (dwarf2_per_objfile *per_objfile,
       comp_unit_head cu_header;
       read_and_check_comp_unit_head (per_objfile, &cu_header, section,
 				     abbrev_section, info_ptr,
-				     rcuh_kind::COMPILE);
+				     section_kind);
 
       /* Save the compilation unit for later lookup.  */
       if (cu_header.unit_type != DW_UT_type)
 	this_cu = per_objfile->per_bfd->allocate_per_cu ();
       else
 	{
+	  if (types_htab == nullptr)
+	    types_htab = allocate_signatured_type_table ();
+
 	  auto sig_type = per_objfile->per_bfd->allocate_signatured_type ();
+	  signatured_type *sig_ptr = sig_type.get ();
 	  sig_type->signature = cu_header.signature;
 	  sig_type->type_offset_in_tu = cu_header.type_cu_offset_in_tu;
 	  this_cu = std::move (sig_type);
+
+	  void **slot = htab_find_slot (types_htab.get (), sig_ptr, INSERT);
+	  gdb_assert (slot != nullptr);
+	  if (*slot != nullptr)
+	    complaint (_("debug type entry at offset %s is duplicate to"
+			 " the entry at offset %s, signature %s"),
+		       sect_offset_str (sect_off),
+		       sect_offset_str (sig_ptr->sect_off),
+		       hex_string (sig_ptr->signature));
+	  *slot = sig_ptr;
 	}
       this_cu->is_debug_types = (cu_header.unit_type == DW_UT_type);
       this_cu->sect_off = sect_off;
@@ -7851,12 +7761,22 @@ read_comp_units_from_section (dwarf2_per_objfile *per_objfile,
 static void
 create_all_comp_units (dwarf2_per_objfile *per_objfile)
 {
+  htab_up types_htab;
+
   read_comp_units_from_section (per_objfile, &per_objfile->per_bfd->info,
-				&per_objfile->per_bfd->abbrev, 0);
+				&per_objfile->per_bfd->abbrev, 0,
+				types_htab, rcuh_kind::COMPILE);
+  for (dwarf2_section_info &section : per_objfile->per_bfd->types)
+    read_comp_units_from_section (per_objfile, &section,
+				  &per_objfile->per_bfd->abbrev, 0,
+				  types_htab, rcuh_kind::TYPE);
 
   dwz_file *dwz = dwarf2_get_dwz_file (per_objfile->per_bfd);
   if (dwz != NULL)
-    read_comp_units_from_section (per_objfile, &dwz->info, &dwz->abbrev, 1);
+    read_comp_units_from_section (per_objfile, &dwz->info, &dwz->abbrev, 1,
+				  types_htab, rcuh_kind::COMPILE);
+
+  per_objfile->per_bfd->signatured_types = std::move (types_htab);
 }
 
 /* Process all loaded DIEs for compilation unit CU, starting at