From: Nathan Sidwell <nathan@acm.org>
Date: Mon, 5 Apr 2021 14:51:28 +0000 (-0700)
Subject: c++: Unneeded export query [PR 99380]
X-Git-Tag: basepoints/gcc-12~268
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dd6f588a7b8878d677af51ff4d1c1e3f9f6f40db;p=thirdparty%2Fgcc.git

c++: Unneeded export query [PR 99380]

This problem got introduced fixing a module numbering problem.  When
preprocessing a header unit, we don't need to send an EXPORT query
unless we're also determining dependencies, or the mapper asked us
to.  Sadly the testsuite isn't set up to test this kind of subtlety.
I manually did that with stdin/stdout.

	PR c++/99380
	gcc/cp/
	* module.cc (name_pending_imports): Drop 'atend' parm.  Don't
	query export when not needed.
	(preprocess_module, preprocessed_module): Adjust.
---

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index d5b7d28ded54..c80c7bcc70f1 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19262,15 +19262,11 @@ module_begin_main_file (cpp_reader *reader, line_maps *lmaps,
    filenames.   */
 
 static void
-name_pending_imports (cpp_reader *reader, bool at_end)
+name_pending_imports (cpp_reader *reader)
 {
   auto *mapper = get_mapper (cpp_main_loc (reader));
 
-  bool only_headers = (flag_preprocess_only
-		       && !bool (mapper->get_flags () & Cody::Flags::NameOnly)
-		       && !cpp_get_deps (reader));
-  if (at_end
-      && (!vec_safe_length (pending_imports) || only_headers))
+  if (!vec_safe_length (pending_imports))
     /* Not doing anything.  */
     return;
 
@@ -19278,40 +19274,56 @@ name_pending_imports (cpp_reader *reader, bool at_end)
 
   auto n = dump.push (NULL);
   dump () && dump ("Resolving direct import names");
+  bool want_deps = (bool (mapper->get_flags () & Cody::Flags::NameOnly)
+		    || cpp_get_deps (reader));
+  bool any = false;
 
-  mapper->Cork ();
   for (unsigned ix = 0; ix != pending_imports->length (); ix++)
     {
       module_state *module = (*pending_imports)[ix];
       gcc_checking_assert (module->is_direct ());
-      if (!module->filename
-	  && !module->visited_p
-	  && (module->is_header () || !only_headers))
+      if (!module->filename && !module->visited_p)
 	{
-	  module->visited_p = true;
-	  Cody::Flags flags = (flag_preprocess_only
-			       ? Cody::Flags::None : Cody::Flags::NameOnly);
+	  bool export_p = (module->module_p
+			   && (module->is_partition () || module->exported_p));
 
-	  if (module->module_p
-	      && (module->is_partition () || module->exported_p))
+	  Cody::Flags flags = Cody::Flags::None;
+	  if (flag_preprocess_only
+	      && !(module->is_header () && !export_p))
+	    {
+	      if (!want_deps)
+		continue;
+	      flags = Cody::Flags::NameOnly;
+	    }
+
+	  if (!any)
+	    {
+	      any = true;
+	      mapper->Cork ();
+	    }
+	  if (export_p)
 	    mapper->ModuleExport (module->get_flatname (), flags);
 	  else
 	    mapper->ModuleImport (module->get_flatname (), flags);
+	  module->visited_p = true;
 	}
     }
-  
-  auto response = mapper->Uncork ();
-  auto r_iter = response.begin ();
-  for (unsigned ix = 0; ix != pending_imports->length (); ix++)
+
+  if (any)
     {
-      module_state *module = (*pending_imports)[ix];
-      if (module->visited_p)
+      auto response = mapper->Uncork ();
+      auto r_iter = response.begin ();
+      for (unsigned ix = 0; ix != pending_imports->length (); ix++)
 	{
-	  module->visited_p = false;
-	  gcc_checking_assert (!module->filename);
+	  module_state *module = (*pending_imports)[ix];
+	  if (module->visited_p)
+	    {
+	      module->visited_p = false;
+	      gcc_checking_assert (!module->filename);
 
-	  module->set_filename (*r_iter);
-	  ++r_iter;
+	      module->set_filename (*r_iter);
+	      ++r_iter;
+	    }
 	}
     }
 
@@ -19384,7 +19396,7 @@ preprocess_module (module_state *module, location_t from_loc,
 	  unsigned n = dump.push (NULL);
 
 	  dump () && dump ("Reading %M preprocessor state", module);
-	  name_pending_imports (reader, false);
+	  name_pending_imports (reader);
 
 	  /* Preserve the state of the line-map.  */
 	  unsigned pre_hwm = LINEMAPS_ORDINARY_USED (line_table);
@@ -19446,7 +19458,7 @@ preprocessed_module (cpp_reader *reader)
 
   dump () && dump ("Completed phase-4 (tokenization) processing");
 
-  name_pending_imports (reader, true);
+  name_pending_imports (reader);
   vec_free (pending_imports);
 
   spans.maybe_init ();