Split struct symtab into two: struct symtab and compunit_symtab.

Currently "symtabs" in gdb are stored as a single linked list of
struct symtab that contains both symbol symtabs (the blockvectors)
and file symtabs (the linetables).

This has led to confusion, bugs, and performance issues.

This patch is conceptually very simple: split struct symtab into
two pieces: one part containing things common across the entire
compilation unit, and one part containing things specific to each
source file.

Example.
For the case of a program built out of these files:

foo.c
  foo1.h
  foo2.h
bar.c
  foo1.h
  bar.h

Today we have a single list of struct symtabs:

objfile -> foo.c -> foo1.h -> foo2.h -> bar.c -> foo1.h -> bar.h -> NULL

where "->" means the "next" pointer in struct symtab.

With this patch, that turns into:

objfile -> foo.c(cu) -> bar.c(cu) -> NULL
            |            |
            v            v
           foo.c        bar.c
            |            |
            v            v
           foo1.h       foo1.h
            |            |
            v            v
           foo2.h       bar.h
            |            |
            v            v
           NULL         NULL

where "foo.c(cu)" and "bar.c(cu)" are struct compunit_symtab objects,
and the files foo.c, etc. are struct symtab objects.

So now, for example, when we want to iterate over all blockvectors
we can now just iterate over the compunit_symtab list.

Plus a lot of the data that was either unused or replicated for each
symtab in a compilation unit now lives in struct compunit_symtab.
E.g., the objfile pointer, the producer string, etc.
I thought of moving "language" out of struct symtab but there is
logic to try to compute the language based on previously seen files,
and I think that's best left as is for now.
With my standard monster benchmark with -readnow (which I can't actually
do, but based on my calculations), whereas today the list requires
77MB to store all the struct symtabs, it now only requires 37MB.
A modest space savings given the gigabytes needed for all the debug info,
etc.  Still, it's nice.  Plus, whereas today we create a copy of dirname
for each source file symtab in a compilation unit, we now only create one
for the compunit.

So this patch is basically just a data structure reorg,
I don't expect significant performance improvements from it.

Notes:

1) A followup patch can do a similar split for struct partial_symtab.
I have left that until after I get the changes I want in to
better utilize .gdb_index (it may affect how we do partial syms).

2) Another followup patch *could* rename struct symtab.
The term "symtab" is ambiguous and has been a source of confusion.
In this patch I'm leaving it alone, calling it the "historical" name
of "filetabs", which is what they are now: just the file-name + line-table.

gdb/ChangeLog:

	Split struct symtab into two: struct symtab and compunit_symtab.
	* amd64-tdep.c (amd64_skip_xmm_prologue): Fetch producer from compunit.
	* block.c (blockvector_for_pc_sect): Change "struct symtab *" argument
	to "struct compunit_symtab *".  All callers updated.
	(set_block_compunit_symtab): Renamed from set_block_symtab.  Change
	"struct symtab *" argument to "struct compunit_symtab *".
	All callers updated.
	(get_block_compunit_symtab): Renamed from get_block_symtab.  Change
	result to "struct compunit_symtab *".  All callers updated.
	(find_iterator_compunit_symtab): Renamed from find_iterator_symtab.
	Change result to "struct compunit_symtab *".  All callers updated.
	* block.h (struct global_block) <compunit_symtab>: Renamed from symtab.
	hange type to "struct compunit_symtab *".  All uses updated.
	(struct block_iterator) <d.compunit_symtab>: Renamed from "d.symtab".
	Change type to "struct compunit_symtab *".  All uses updated.
	* buildsym.c (struct buildsym_compunit): New struct.
	(subfiles, buildsym_compdir, buildsym_objfile, main_subfile): Delete.
	(buildsym_compunit): New static global.
	(finish_block_internal): Update to fetch objfile from
	buildsym_compunit.
	(make_blockvector): Delete objfile argument.
	(start_subfile): Rewrite to use buildsym_compunit.  Don't initialize
	debugformat, producer.
	(start_buildsym_compunit): New function.
	(free_buildsym_compunit): Renamed from free_subfiles_list.
	All callers updated.
	(patch_subfile_names): Rewrite to use buildsym_compunit.
	(get_compunit_symtab): New function.
	(get_macro_table): Delete argument comp_dir.  All callers updated.
	(start_symtab): Change result to "struct compunit_symtab *".
	All callers updated.  Create the subfile of the main source file.
	(watch_main_source_file_lossage): Rewrite to use buildsym_compunit.
	(reset_symtab_globals): Update.
	(end_symtab_get_static_block): Update to use buildsym_compunit.
	(end_symtab_without_blockvector): Rewrite.
	(end_symtab_with_blockvector): Change result to
	"struct compunit_symtab *".  All callers updated.
	Update to use buildsym_compunit.  Don't set symtab->dirname,
	instead set it in the compunit.
	Explicitly make sure main symtab is first in its list.
	Set debugformat, producer, blockvector, block_line_section, and
	macrotable in the compunit.
	(end_symtab_from_static_block): Change result to
	"struct compunit_symtab *".  All callers updated.
	(end_symtab, end_expandable_symtab): Ditto.
	(set_missing_symtab): Change symtab argument to
	"struct compunit_symtab *".  All callers updated.
	(augment_type_symtab): Ditto.
	(record_debugformat): Update to use buildsym_compunit.
	(record_producer): Update to use buildsym_compunit.
	* buildsym.h (struct subfile) <dirname>: Delete.
	<producer, debugformat>: Delete.
	<buildsym_compunit>: New member.
	(get_compunit_symtab): Declare.
	* dwarf2read.c (struct type_unit_group) <compunit_symtab>: Renamed
	from primary_symtab.  Change type to "struct compunit_symtab *".
	All uses updated.
	(dwarf2_start_symtab): Change result to "struct compunit_symtab *".
	All callers updated.
	(dwarf_decode_macros): Delete comp_dir argument.  All callers updated.
	(struct dwarf2_per_cu_quick_data) <compunit_symtab>: Renamed from
	symtab.  Change type to "struct compunit_symtab *".  All uses updated.
	(dw2_instantiate_symtab): Change result to "struct compunit_symtab *".
	All callers updated.
	(dw2_find_last_source_symtab): Ditto.
	(dw2_lookup_symbol): Ditto.
	(recursively_find_pc_sect_compunit_symtab): Renamed from
	recursively_find_pc_sect_symtab.  Change result to
	"struct compunit_symtab *".  All callers updated.
	(dw2_find_pc_sect_compunit_symtab): Renamed from
	dw2_find_pc_sect_symtab.  Change result to
	"struct compunit_symtab *".  All callers updated.
	(get_compunit_symtab): Renamed from get_symtab.  Change result to
	"struct compunit_symtab *".  All callers updated.
	(recursively_compute_inclusions): Change type of immediate_parent
	argument to "struct compunit_symtab *".  All callers updated.
	(compute_compunit_symtab_includes): Renamed from
	compute_symtab_includes.  All callers updated.  Rewrite to compute
	includes of compunit_symtabs and not symtabs.
	(process_full_comp_unit): Update to work with struct compunit_symtab.
	(process_full_type_unit): Ditto.
	(dwarf_decode_lines_1): Delete argument comp_dir.  All callers updated.
	(dwarf_decode_lines): Remove special case handling of main subfile.
	(macro_start_file): Delete argument comp_dir.  All callers updated.
	(dwarf_decode_macro_bytes): Ditto.
	* guile/scm-block.c (bkscm_print_block_syms_progress_smob): Update to
	use struct compunit_symtab.
	* i386-tdep.c (i386_skip_prologue): Fetch producer from compunit.
	* jit.c (finalize_symtab): Build compunit_symtab.
	* jv-lang.c (get_java_class_symtab): Change result to
	"struct compunit_symtab *".  All callers updated.
	* macroscope.c (sal_macro_scope): Fetch macro table from compunit.
	* macrotab.c (struct macro_table) <compunit_symtab>: Renamed from
	comp_dir.  Change type to "struct compunit_symtab *".
	All uses updated.
	(new_macro_table): Change comp_dir argument to cust,
	"struct compunit_symtab *".  All callers updated.
	* maint.c (struct cmd_stats) <nr_compunit_symtabs>: Renamed from
	nr_primary_symtabs.  All uses updated.
	(count_symtabs_and_blocks): Update to handle compunits.
	(report_command_stats): Update output, "primary symtabs" renamed to
	"compunits".
	* mdebugread.c (new_symtab): Change result to
	"struct compunit_symtab *".  All callers updated.
	(parse_procedure): Change type of search_symtab argument to
	"struct compunit_symtab *".  All callers updated.
	* objfiles.c (objfile_relocate1): Loop over blockvectors in a
	separate loop.
	* objfiles.h (struct objfile) <compunit_symtabs>: Renamed from
	symtabs.  Change type to "struct compunit_symtab *".  All uses updated.
	(ALL_OBJFILE_FILETABS): Renamed from ALL_OBJFILE_SYMTABS.
	All uses updated.
	(ALL_OBJFILE_COMPUNITS): Renamed from ALL_OBJFILE_PRIMARY_SYMTABS.
	All uses updated.
	(ALL_FILETABS): Renamed from ALL_SYMTABS.  All uses updated.
	(ALL_COMPUNITS): Renamed from ALL_PRIMARY_SYMTABS.  All uses updated.
	* psympriv.h (struct partial_symtab) <compunit_symtab>: Renamed from
	symtab.  Change type to "struct compunit_symtab *".  All uses updated.
	* psymtab.c (psymtab_to_symtab): Change result type to
	"struct compunit_symtab *".  All callers updated.
	(find_pc_sect_compunit_symtab_from_partial): Renamed from
	find_pc_sect_symtab_from_partial.  Change result type to
	"struct compunit_symtab *".  All callers updated.
	(lookup_symbol_aux_psymtabs): Change result type to
	"struct compunit_symtab *".  All callers updated.
	(find_last_source_symtab_from_partial): Ditto.
	* python/py-symtab.c (stpy_get_producer): Fetch producer from compunit.
	* source.c (forget_cached_source_info_for_objfile): Fetch debugformat
	and macro_table from compunit.
	* symfile-debug.c (debug_qf_find_last_source_symtab): Change result
	type to "struct compunit_symtab *".  All callers updated.
	(debug_qf_lookup_symbol): Ditto.
	(debug_qf_find_pc_sect_compunit_symtab): Renamed from
	debug_qf_find_pc_sect_symtab, change result type to
	"struct compunit_symtab *".  All callers updated.
	* symfile.c (allocate_symtab): Delete objfile argument.
	New argument cust.
	(allocate_compunit_symtab): New function.
	(add_compunit_symtab_to_objfile): New function.
	* symfile.h (struct quick_symbol_functions) <lookup_symbol>:
	Change result type to "struct compunit_symtab *".  All uses updated.
	<find_pc_sect_compunit_symtab>: Renamed from find_pc_sect_symtab.
	Change result type to "struct compunit_symtab *".  All uses updated.
	* symmisc.c (print_objfile_statistics): Compute blockvector count in
	separate loop.
	(dump_symtab_1): Update test for primary source symtab.
	(maintenance_info_symtabs): Update to handle compunit symtabs.
	(maintenance_check_symtabs): Ditto.
	* symtab.c (set_primary_symtab): Delete.
	(compunit_primary_filetab): New function.
	(compunit_language): New function.
	(iterate_over_some_symtabs): Change type of arguments "first",
	"after_last" to "struct compunit_symtab *".  All callers updated.
	Update to loop over symtabs in each compunit.
	(error_in_psymtab_expansion): Rename symtab argument to cust,
	and change type to "struct compunit_symtab *".  All callers updated.
	(find_pc_sect_compunit_symtab): Renamed from find_pc_sect_symtab.
	Change result type to "struct compunit_symtab *".  All callers updated.
	(find_pc_compunit_symtab): Renamed from find_pc_symtab.
	Change result type to "struct compunit_symtab *".  All callers updated.
	(find_pc_sect_line): Only loop over symtabs within selected compunit
	instead of all symtabs in the objfile.
	* symtab.h (struct symtab) <blockvector>: Moved to compunit_symtab.
	<compunit_symtab> New member.
	<block_line_section>: Moved to compunit_symtab.
	<locations_valid>: Ditto.
	<epilogue_unwind_valid>: Ditto.
	<macro_table>: Ditto.
	<dirname>: Ditto.
	<debugformat>: Ditto.
	<producer>: Ditto.
	<objfile>: Ditto.
	<call_site_htab>: Ditto.
	<includes>: Ditto.
	<user>: Ditto.
	<primary>: Delete
	(SYMTAB_COMPUNIT): New macro.
	(SYMTAB_BLOCKVECTOR): Update definition.
	(SYMTAB_OBJFILE): Update definition.
	(SYMTAB_DIRNAME): Update definition.
	(struct compunit_symtab): New type.  Common members among all source
	symtabs within a compilation unit moved here.  All uses updated.
	(COMPUNIT_OBJFILE): New macro.
	(COMPUNIT_FILETABS): New macro.
	(COMPUNIT_DEBUGFORMAT): New macro.
	(COMPUNIT_PRODUCER): New macro.
	(COMPUNIT_DIRNAME): New macro.
	(COMPUNIT_BLOCKVECTOR): New macro.
	(COMPUNIT_BLOCK_LINE_SECTION): New macro.
	(COMPUNIT_LOCATIONS_VALID): New macro.
	(COMPUNIT_EPILOGUE_UNWIND_VALID): New macro.
	(COMPUNIT_CALL_SITE_HTAB): New macro.
	(COMPUNIT_MACRO_TABLE): New macro.
	(ALL_COMPUNIT_FILETABS): New macro.
	(compunit_symtab_ptr): New typedef.
	(DEF_VEC_P (compunit_symtab_ptr)): New vector type.

gdb/testsuite/ChangeLog:

	* gdb.base/maint.exp: Update expected output.

1 files changed, 36 insertions, 32 deletions

diff --git a/gdb/psymtab.c b/gdb/psymtab.c
index da22d21..86ea80d 100644
--- a/gdb/psymtab.c
+++ b/gdb/psymtab.c
@@ -67,8 +67,8 @@ static struct partial_symbol *find_pc_sect_psymbol (struct objfile *,
 static void fixup_psymbol_section (struct partial_symbol *psym,
 				   struct objfile *objfile);
 
-static struct symtab *psymtab_to_symtab (struct objfile *objfile,
-					 struct partial_symtab *pst);
+static struct compunit_symtab *psymtab_to_symtab (struct objfile *objfile,
+						  struct partial_symtab *pst);
 
 /* Ensure that the partial symbols for OBJFILE have been loaded.  This
    function always returns its argument, as a convenience.  */
@@ -135,7 +135,7 @@ partial_map_expand_apply (struct objfile *objfile,
 			  int (*callback) (struct symtab *, void *),
 			  void *data)
 {
-  struct symtab *last_made = objfile->symtabs;
+  struct compunit_symtab *last_made = objfile->compunit_symtabs;
 
   /* Shared psymtabs should never be seen here.  Instead they should
      be handled properly by the caller.  */
@@ -150,7 +150,7 @@ partial_map_expand_apply (struct objfile *objfile,
   psymtab_to_symtab (objfile, pst);
 
   return iterate_over_some_symtabs (name, real_path, callback, data,
-				    objfile->symtabs, last_made);
+				    objfile->compunit_symtabs, last_made);
 }
 
 /* Implementation of the map_symtabs_matching_filename method.  */
@@ -370,11 +370,12 @@ find_pc_sect_psymtab (struct objfile *objfile, CORE_ADDR pc,
   return NULL;
 }
 
-static struct symtab *
-find_pc_sect_symtab_from_partial (struct objfile *objfile,
-				  struct bound_minimal_symbol msymbol,
-				  CORE_ADDR pc, struct obj_section *section,
-				  int warn_if_readin)
+static struct compunit_symtab *
+find_pc_sect_compunit_symtab_from_partial (struct objfile *objfile,
+					   struct bound_minimal_symbol msymbol,
+					   CORE_ADDR pc,
+					   struct obj_section *section,
+					   int warn_if_readin)
 {
   struct partial_symtab *ps = find_pc_sect_psymtab (objfile, pc, section,
 						    msymbol);
@@ -388,7 +389,7 @@ find_pc_sect_symtab_from_partial (struct objfile *objfile,
 (Internal error: pc %s in read in psymtab, but not in symtab.)\n"),
 		 paddress (get_objfile_arch (objfile), pc));
       psymtab_to_symtab (objfile, ps);
-      return ps->symtab;
+      return ps->compunit_symtab;
     }
   return NULL;
 }
@@ -494,14 +495,14 @@ fixup_psymbol_section (struct partial_symbol *psym, struct objfile *objfile)
   fixup_section (&psym->ginfo, addr, objfile);
 }
 
-static struct symtab *
+static struct compunit_symtab *
 lookup_symbol_aux_psymtabs (struct objfile *objfile,
 			    int block_index, const char *name,
 			    const domain_enum domain)
 {
   struct partial_symtab *ps;
   const int psymtab_index = (block_index == GLOBAL_BLOCK ? 1 : 0);
-  struct symtab *stab_best = NULL;
+  struct compunit_symtab *stab_best = NULL;
 
   ALL_OBJFILE_PSYMTABS_REQUIRED (objfile, ps)
   {
@@ -509,11 +510,11 @@ lookup_symbol_aux_psymtabs (struct objfile *objfile,
 					      psymtab_index, domain))
       {
 	struct symbol *sym = NULL;
-	struct symtab *stab = psymtab_to_symtab (objfile, ps);
+	struct compunit_symtab *stab = psymtab_to_symtab (objfile, ps);
 	/* Note: While psymtab_to_symtab can return NULL if the partial symtab
 	   is empty, we can assume it won't here because lookup_partial_symbol
 	   succeeded.  */
-	const struct blockvector *bv = SYMTAB_BLOCKVECTOR (stab);
+	const struct blockvector *bv = COMPUNIT_BLOCKVECTOR (stab);
 	struct block *block = BLOCKVECTOR_BLOCK (bv, block_index);
 
 	/* Some caution must be observed with overloaded functions
@@ -760,7 +761,7 @@ lookup_partial_symbol (struct objfile *objfile,
    which can happen.  Otherwise the result is the primary symtab
    that contains PST.  */
 
-static struct symtab *
+static struct compunit_symtab *
 psymtab_to_symtab (struct objfile *objfile, struct partial_symtab *pst)
 {
   /* If it is a shared psymtab, find an unshared psymtab that includes
@@ -769,8 +770,8 @@ psymtab_to_symtab (struct objfile *objfile, struct partial_symtab *pst)
     pst = pst->user;
 
   /* If it's been looked up before, return it.  */
-  if (pst->symtab)
-    return pst->symtab;
+  if (pst->compunit_symtab)
+    return pst->compunit_symtab;
 
   /* If it has not yet been read in, read it.  */
   if (!pst->readin)
@@ -781,10 +782,7 @@ psymtab_to_symtab (struct objfile *objfile, struct partial_symtab *pst)
       do_cleanups (back_to);
     }
 
-  if (pst->symtab != NULL)
-    gdb_assert (pst->symtab->primary);
-
-  return pst->symtab;
+  return pst->compunit_symtab;
 }
 
 static void
@@ -846,7 +844,13 @@ find_last_source_symtab_from_partial (struct objfile *ofp)
 			  "readin pst found and no symtabs."));
 	}
       else
-	return psymtab_to_symtab (ofp, cs_pst);
+	{
+	  struct compunit_symtab *cust = psymtab_to_symtab (ofp, cs_pst);
+
+	  if (cust == NULL)
+	    return NULL;
+	  return compunit_primary_filetab (cust);
+	}
     }
   return NULL;
 }
@@ -986,7 +990,7 @@ dump_psymtab (struct objfile *objfile, struct partial_symtab *psymtab,
     {
       fprintf_filtered (outfile,
 			"  Full symtab was read (at ");
-      gdb_print_host_address (psymtab->symtab, outfile);
+      gdb_print_host_address (psymtab->compunit_symtab, outfile);
       fprintf_filtered (outfile, " by function at ");
       gdb_print_host_address (psymtab->read_symtab, outfile);
       fprintf_filtered (outfile, ")\n");
@@ -1261,12 +1265,12 @@ map_matching_symbols_psymtab (struct objfile *objfile,
 	  || match_partial_symbol (objfile, ps, global, name, namespace, match,
 				   ordered_compare))
 	{
-	  struct symtab *s = psymtab_to_symtab (objfile, ps);
+	  struct compunit_symtab *cust = psymtab_to_symtab (objfile, ps);
 	  struct block *block;
 
-	  if (s == NULL)
+	  if (cust == NULL)
 	    continue;
-	  block = BLOCKVECTOR_BLOCK (SYMTAB_BLOCKVECTOR (s), block_kind);
+	  block = BLOCKVECTOR_BLOCK (COMPUNIT_BLOCKVECTOR (cust), block_kind);
 	  if (map_block (name, namespace, objfile, block,
 			 callback, data, match))
 	    return;
@@ -1436,7 +1440,7 @@ const struct quick_symbol_functions psym_functions =
   read_psymtabs_with_fullname,
   map_matching_symbols_psymtab,
   expand_symtabs_matching_via_partial,
-  find_pc_sect_symtab_from_partial,
+  find_pc_sect_compunit_symtab_from_partial,
   map_symbol_filenames_psymtab
 };
 
@@ -1748,7 +1752,7 @@ allocate_psymtab (const char *filename, struct objfile *objfile)
   memset (psymtab, 0, sizeof (struct partial_symtab));
   psymtab->filename = bcache (filename, strlen (filename) + 1,
 			      objfile->per_bfd->filename_cache);
-  psymtab->symtab = NULL;
+  psymtab->compunit_symtab = NULL;
 
   /* Prepend it to the psymtab list for the objfile it belongs to.
      Psymtabs are searched in most recent inserted -> least recent
@@ -2005,7 +2009,7 @@ maintenance_check_psymtabs (char *ignore, int from_tty)
 {
   struct symbol *sym;
   struct partial_symbol **psym;
-  struct symtab *s = NULL;
+  struct compunit_symtab *cust = NULL;
   struct partial_symtab *ps;
   const struct blockvector *bv;
   struct objfile *objfile;
@@ -2019,7 +2023,7 @@ maintenance_check_psymtabs (char *ignore, int from_tty)
     /* We don't call psymtab_to_symtab here because that may cause symtab
        expansion.  When debugging a problem it helps if checkers leave
        things unchanged.  */
-    s = ps->symtab;
+    cust = ps->compunit_symtab;
 
     /* First do some checks that don't require the associated symtab.  */
     if (ps->texthigh < ps->textlow)
@@ -2035,9 +2039,9 @@ maintenance_check_psymtabs (char *ignore, int from_tty)
       }
 
     /* Now do checks requiring the associated symtab.  */
-    if (s == NULL)
+    if (cust == NULL)
       continue;
-    bv = SYMTAB_BLOCKVECTOR (s);
+    bv = COMPUNIT_BLOCKVECTOR (cust);
     b = BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK);
     psym = objfile->static_psymbols.list + ps->statics_offset;
     length = ps->n_static_syms;