Prefer d_linkonce_linkage over d_comdat_linkage.

Author: ibuclaw

gcc/d/ChangeLog

@@ -24,6 +24,22 @@
 	(build_closure): Don't set chain field for functions without context
 	pointer.
 
+2018-01-21  Iain Buclaw  <[email protected]>
+
+	* decl.cc (DeclVisitor::visit(StructDeclaration)): Mark compiler
+	generated symbols as DECL_ONE_ONLY instead of DECL_COMDAT.
+	(DeclVisitor::visit(ClassDeclaration)): Likewise.
+	(DeclVisitor::visit(InterfaceDeclaration)): Likewise.
+	(DeclVisitor::visit(EnumDeclaration)): Likewise.
+	(get_symbol_decl): Mark template instantiations as DECL_ONE_ONLY
+	instead of DECL_COMDAT.  Don't call mark_needed.
+	(declare_extern_var): Don't call mark_needed.
+	(d_finish_decl): Remove zero initializer for common symbols.
+	(finish_thunk): Don't call d_comdat_linkage on generic thunk.
+	(d_comdat_linkage): Don't set DECL_DECLARED_INLINE on functions.
+	* typeinfo.cc (TypeInfoDeclVisitor::visit(TypeInfoDeclaration)): Mark
+	built-in typeinfo symbols as DECL_ONE_ONLY instead of DECL_COMDAT.
+
 2018-01-21  Iain Buclaw  <[email protected]>
 
 	* d-lang.cc (d_init): Disable flag_weak if not supported.

gcc/d/decl.cc

@@ -314,7 +314,7 @@ class DeclVisitor : public Visitor
     DECL_INITIAL (d->sinit) = layout_struct_initializer (d);
 
     if (d->isInstantiated ())
-      d_comdat_linkage (d->sinit);
+      d_linkonce_linkage (d->sinit);
 
     d_finish_decl (d->sinit);
 
@@ -420,13 +420,13 @@ class DeclVisitor : public Visitor
 
     /* Generate static initialiser.  */
     DECL_INITIAL (d->sinit) = layout_class_initializer (d);
-    d_comdat_linkage (d->sinit);
+    d_linkonce_linkage (d->sinit);
     d_finish_decl (d->sinit);
 
     /* Put out the TypeInfo.  */
     create_typeinfo (d->type, NULL);
     DECL_INITIAL (d->csym) = layout_classinfo (d);
-    d_comdat_linkage (d->csym);
+    d_linkonce_linkage (d->csym);
     d_finish_decl (d->csym);
 
     /* Put out the vtbl[].  */
@@ -487,7 +487,7 @@ class DeclVisitor : public Visitor
     d->type->vtinfo->accept (this);
 
     DECL_INITIAL (d->csym) = layout_classinfo (d);
-    d_comdat_linkage (d->csym);
+    d_linkonce_linkage (d->csym);
     d_finish_decl (d->csym);
 
     /* Add this decl to the current binding level.  */
@@ -524,7 +524,7 @@ class DeclVisitor : public Visitor
 	DECL_INITIAL (d->sinit) = build_expr (tc->sym->defaultval, true);
 
 	if (d->isInstantiated ())
-	  d_comdat_linkage (d->sinit);
+	  d_linkonce_linkage (d->sinit);
 
 	d_finish_decl (d->sinit);
 
@@ -1152,6 +1152,7 @@ get_symbol_decl (Declaration *decl)
 	{
 	  TREE_PUBLIC (decl->csym) = 1;
 	  DECL_ARTIFICIAL (decl->csym) = 1;
+	  DECL_DECLARED_INLINE_P (decl->csym) = 1;
 	  d_comdat_linkage (decl->csym);
 	}
 
@@ -1229,13 +1230,7 @@ get_symbol_decl (Declaration *decl)
 	  else
 	    DECL_EXTERNAL (decl->csym) = 1;
 
-	  d_comdat_linkage (decl->csym);
-
-	  /* Normally the backend only emits COMDAT things when they are needed.
-	     If this decl is meant to be externally visible, then make sure that
-	     to mark it so that it is indeed needed.  */
-	  if (TREE_PUBLIC (decl->csym))
-	    mark_needed (decl->csym);
+	  d_linkonce_linkage (decl->csym);
 	}
       else
 	{
@@ -1300,9 +1295,6 @@ declare_extern_var (tree ident, tree type)
   TREE_STATIC (decl) = 1;
   TREE_PUBLIC (decl) = 1;
 
-  /* Mark it needed so we don't forget to emit it.  */
-  mark_needed (decl);
-
   /* The decl has not been defined -- yet.  */
   DECL_EXTERNAL (decl) = 1;
 
@@ -1476,6 +1468,12 @@ d_finish_decl (tree decl)
 	}
     }
 
+  /* Without weak symbols, symbol should be put in .common, but that can't
+     be done if there is a non-zero initializer.  */
+  if (DECL_COMDAT (decl) && DECL_COMMON (decl)
+      && initializer_zerop (DECL_INITIAL (decl)))
+    DECL_INITIAL (decl) = error_mark_node;
+
   /* Add this decl to the current binding level.  */
   d_pushdecl (decl);
 
@@ -1615,8 +1613,6 @@ finish_thunk (tree thunk, tree function)
 
       if (!stdarg_p (TREE_TYPE (thunk)))
 	{
-	  /* Put generic thunk into COMDAT.  */
-	  d_comdat_linkage (thunk);
 	  thunk_node->create_edge (funcn, NULL, thunk_node->count);
 	  thunk_node->expand_thunk (false, true);
 	}
@@ -2159,14 +2155,6 @@ d_comdat_group (tree decl)
 void
 d_comdat_linkage (tree decl)
 {
-  /* COMDAT definitions have to be public.  */
-  if (!TREE_PUBLIC (decl))
-    return;
-
-  /* Necessary to allow DECL_ONE_ONLY or DECL_WEAK functions to be inlined.  */
-  if (TREE_CODE (decl) == FUNCTION_DECL)
-    DECL_DECLARED_INLINE_P (decl) = 1;
-
   if (flag_weak)
     make_decl_one_only (decl, d_comdat_group (decl));
   else if (TREE_CODE (decl) == FUNCTION_DECL

gcc/d/typeinfo.cc

@@ -1187,6 +1187,28 @@ layout_classinfo_interfaces (ClassDeclaration *decl)
   return type;
 }
 
+/* Returns true if the TypeInfo for type should be placed in
+   the runtime library.  */
+
+static bool
+builtin_typeinfo_p (Type *type)
+{
+  if (type->isTypeBasic () || type->ty == Tclass || type->ty == Tnull)
+    return !type->mod;
+
+  if (type->ty == Tarray)
+    {
+      /* Strings are so common, make them builtin.  */
+      Type *next = type->nextOf ();
+      return !type->mod
+	&& ((next->isTypeBasic () != NULL && !next->mod)
+	    || (next->ty == Tchar && next->mod == MODimmutable)
+	    || (next->ty == Tchar && next->mod == MODconst));
+    }
+
+  return false;
+}
+
 /* Implements a visitor interface to create the decl tree for TypeInfo decls.
    TypeInfo_Class objects differ in that they also have information about
    the class type packed immediately after the TypeInfo symbol.
@@ -1213,7 +1235,11 @@ class TypeInfoDeclVisitor : public Visitor
 
     /* Built-in typeinfo will be referenced as one-only.  */
     gcc_assert (!tid->isInstantiated ());
-    d_comdat_linkage (tid->csym);
+
+    if (builtin_typeinfo_p (tid->tinfo))
+      d_linkonce_linkage (tid->csym);
+    else
+      d_comdat_linkage (tid->csym);
   }
 
   void visit (TypeInfoClassDeclaration *tid)
@@ -1347,28 +1373,6 @@ get_cpp_typeinfo_decl (ClassDeclaration *decl)
   return decl->cpp_type_info_ptr_sym;
 }
 
-/* Returns true if the TypeInfo for type should be placed in
-   the runtime library.  */
-
-static bool
-builtin_typeinfo_p (Type *type)
-{
-  if (type->isTypeBasic () || type->ty == Tclass || type->ty == Tnull)
-    return !type->mod;
-
-  if (type->ty == Tarray)
-    {
-      /* Strings are so common, make them builtin.  */
-      Type *next = type->nextOf ();
-      return !type->mod
-	&& ((next->isTypeBasic () != NULL && !next->mod)
-	    || (next->ty == Tchar && next->mod == MODimmutable)
-	    || (next->ty == Tchar && next->mod == MODconst));
-    }
-
-  return false;
-}
-
 /* Get the exact TypeInfo for TYPE, if it doesn't exist, create it.  */
 
 void