Have expand_symtabs_matching work for already-expanded CUs

Currently, gdb will search the already-expanded symtabs in one loop,
and then also expand matching symtabs in another loop.  However, this
is somewhat inefficient -- when searching the already-expanded
symtabs, all such symtabs are examined.  However, the various "quick"
implementations already know which subset of symtabs might have a
match.

This changes the contract of expand_symtabs_matching to also call the
callback for an already-expanded symtab.  With this change, and some
subsequent enabling changes, the number of searched symtabs should
sometimes be reduced.  This also cuts down on the amount of redundant
code.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=16994
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=16998
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30736
Acked-By: Simon Marchi <simon.marchi@efficios.com>

2 files changed, 30 insertions, 17 deletions

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 2487aca..2bc9676 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -1535,6 +1535,31 @@ struct readnow_functions : public dwarf2_base_index_functions
      domain_search_flags domain,
      expand_symtabs_lang_matcher lang_matcher) override
   {
+    dwarf2_per_objfile *per_objfile = get_dwarf2_per_objfile (objfile);
+    auto_bool_vector cus_to_skip;
+    dw_expand_symtabs_matching_file_matcher (per_objfile, cus_to_skip,
+					     file_matcher);
+
+    for (const auto &per_cu : per_objfile->per_bfd->all_units)
+      {
+	QUIT;
+
+	/* Skip various types of unit that should not be searched
+	   directly: partial units and dummy units.  */
+	if (/* Note that we request the non-strict unit type here.  If
+	       there was an error while reading, like in
+	       dw-form-strx-out-of-bounds.exp, then the unit type may
+	       not be set.  */
+	    per_cu->unit_type (false) == DW_UT_partial
+	    || per_cu->unit_type (false) == 0
+	    || per_objfile->get_symtab (per_cu.get ()) == nullptr)
+	  continue;
+	if (!dw2_expand_symtabs_matching_one (per_cu.get (), per_objfile,
+					      cus_to_skip, file_matcher,
+					      expansion_notify,
+					      lang_matcher))
+	  return false;
+      }
     return true;
   }
 };
@@ -1992,13 +2017,15 @@ dw2_expand_symtabs_matching_one
 	return true;
     }
 
-  bool symtab_was_null = !per_objfile->symtab_set_p (per_cu);
   compunit_symtab *symtab
     = dw2_instantiate_symtab (per_cu, per_objfile, false);
   gdb_assert (symtab != nullptr);
 
-  if (expansion_notify != NULL && symtab_was_null)
-    return expansion_notify (symtab);
+  if (expansion_notify != nullptr)
+    {
+      cus_to_skip.set (per_cu->index, true);
+      return expansion_notify (symtab);
+    }
 
   return true;
 }
@@ -2030,13 +2057,6 @@ dw_expand_symtabs_matching_file_matcher
 	  continue;
 	}
 
-      /* We only need to look at symtabs not already expanded.  */
-      if (per_objfile->symtab_set_p (per_cu.get ()))
-	{
-	  cus_to_skip.set (per_cu->index, true);
-	  continue;
-	}
-
       if (per_cu->fnd != nullptr)
 	{
 	  file_and_directory *fnd = per_cu->fnd.get ();
@@ -14675,10 +14695,6 @@ cooked_index_functions::expand_symtabs_matching
 	{
 	  QUIT;
 
-	  /* No need to consider symbols from expanded CUs.  */
-	  if (per_objfile->symtab_set_p (entry->per_cu))
-	    continue;
-
 	  /* We don't need to consider symbols from some CUs.  */
 	  if (cus_to_skip.is_set (entry->per_cu->index))
 	    continue;
diff --git a/gdb/psymtab.c b/gdb/psymtab.c
index c19e4f2..70a7ca4 100644
--- a/gdb/psymtab.c
+++ b/gdb/psymtab.c
@@ -914,9 +914,6 @@ psymbol_functions::expand_symtabs_matching
     {
       QUIT;
 
-      if (ps->readin_p (objfile))
-	continue;
-
       if (file_matcher)
 	{
 	  bool match;