2012-10-10 Basile Starynkevitch <basile@starynkevitch.net>

	MELT branch merged with trunk rev 192289 using svnmerge.py



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/melt-branch@192291 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 257 insertions, 0 deletions

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index aad3d0b26f7..688a72332ce 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -2696,6 +2696,7 @@ get_guard (tree decl)
       TREE_STATIC (guard) = TREE_STATIC (decl);
       DECL_COMMON (guard) = DECL_COMMON (decl);
       DECL_COMDAT (guard) = DECL_COMDAT (decl);
+      DECL_TLS_MODEL (guard) = DECL_TLS_MODEL (decl);
       if (DECL_ONE_ONLY (decl))
 	make_decl_one_only (guard, cxx_comdat_group (guard));
       if (TREE_PUBLIC (decl))
@@ -2780,6 +2781,187 @@ set_guard (tree guard)
 			       tf_warning_or_error);
 }
 
+/* Returns true iff we can tell that VAR does not have a dynamic
+   initializer.  */
+
+static bool
+var_defined_without_dynamic_init (tree var)
+{
+  /* If it's defined in another TU, we can't tell.  */
+  if (DECL_EXTERNAL (var))
+    return false;
+  /* If it has a non-trivial destructor, registering the destructor
+     counts as dynamic initialization.  */
+  if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (var)))
+    return false;
+  /* If it's in this TU, its initializer has been processed.  */
+  gcc_assert (DECL_INITIALIZED_P (var));
+  /* If it has no initializer or a constant one, it's not dynamic.  */
+  return (!DECL_NONTRIVIALLY_INITIALIZED_P (var)
+	  || DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (var));
+}
+
+/* Returns true iff VAR is a variable that needs uses to be
+   wrapped for possible dynamic initialization.  */
+
+static bool
+var_needs_tls_wrapper (tree var)
+{
+  return (DECL_THREAD_LOCAL_P (var)
+	  && !DECL_GNU_TLS_P (var)
+	  && !DECL_FUNCTION_SCOPE_P (var)
+	  && !var_defined_without_dynamic_init (var));
+}
+
+/* Get a FUNCTION_DECL for the init function for the thread_local
+   variable VAR.  The init function will be an alias to the function
+   that initializes all the non-local TLS variables in the translation
+   unit.  The init function is only used by the wrapper function.  */
+
+static tree
+get_tls_init_fn (tree var)
+{
+  /* Only C++11 TLS vars need this init fn.  */
+  if (!var_needs_tls_wrapper (var))
+    return NULL_TREE;
+
+  tree sname = mangle_tls_init_fn (var);
+  tree fn = IDENTIFIER_GLOBAL_VALUE (sname);
+  if (!fn)
+    {
+      fn = build_lang_decl (FUNCTION_DECL, sname,
+			    build_function_type (void_type_node,
+						 void_list_node));
+      SET_DECL_LANGUAGE (fn, lang_c);
+      TREE_PUBLIC (fn) = TREE_PUBLIC (var);
+      DECL_ARTIFICIAL (fn) = true;
+      DECL_COMDAT (fn) = DECL_COMDAT (var);
+      DECL_EXTERNAL (fn) = true;
+      if (DECL_ONE_ONLY (var))
+	make_decl_one_only (fn, cxx_comdat_group (fn));
+      if (TREE_PUBLIC (var))
+	{
+	  tree obtype = strip_array_types (non_reference (TREE_TYPE (var)));
+	  /* If the variable might have static initialization, make the
+	     init function a weak reference.  */
+	  if ((!TYPE_NEEDS_CONSTRUCTING (obtype)
+	       || TYPE_HAS_CONSTEXPR_CTOR (obtype))
+	      && TARGET_SUPPORTS_WEAK)
+	    declare_weak (fn);
+	  else
+	    DECL_WEAK (fn) = DECL_WEAK (var);
+	}
+      DECL_VISIBILITY (fn) = DECL_VISIBILITY (var);
+      DECL_VISIBILITY_SPECIFIED (fn) = DECL_VISIBILITY_SPECIFIED (var);
+      DECL_DLLIMPORT_P (fn) = DECL_DLLIMPORT_P (var);
+      DECL_IGNORED_P (fn) = 1;
+      mark_used (fn);
+
+      DECL_BEFRIENDING_CLASSES (fn) = var;
+
+      SET_IDENTIFIER_GLOBAL_VALUE (sname, fn);
+    }
+  return fn;
+}
+
+/* Get a FUNCTION_DECL for the init wrapper function for the thread_local
+   variable VAR.  The wrapper function calls the init function (if any) for
+   VAR and then returns a reference to VAR.  The wrapper function is used
+   in place of VAR everywhere VAR is mentioned.  */
+
+tree
+get_tls_wrapper_fn (tree var)
+{
+  /* Only C++11 TLS vars need this wrapper fn.  */
+  if (!var_needs_tls_wrapper (var))
+    return NULL_TREE;
+
+  tree sname = mangle_tls_wrapper_fn (var);
+  tree fn = IDENTIFIER_GLOBAL_VALUE (sname);
+  if (!fn)
+    {
+      /* A named rvalue reference is an lvalue, so the wrapper should
+	 always return an lvalue reference.  */
+      tree type = non_reference (TREE_TYPE (var));
+      type = build_reference_type (type);
+      tree fntype = build_function_type (type, void_list_node);
+      fn = build_lang_decl (FUNCTION_DECL, sname, fntype);
+      SET_DECL_LANGUAGE (fn, lang_c);
+      TREE_PUBLIC (fn) = TREE_PUBLIC (var);
+      DECL_ARTIFICIAL (fn) = true;
+      DECL_IGNORED_P (fn) = 1;
+      /* The wrapper is inline and emitted everywhere var is used.  */
+      DECL_DECLARED_INLINE_P (fn) = true;
+      if (TREE_PUBLIC (var))
+	{
+	  comdat_linkage (fn);
+#ifdef HAVE_GAS_HIDDEN
+	  /* Make the wrapper bind locally; there's no reason to share
+	     the wrapper between multiple shared objects.  */
+	  DECL_VISIBILITY (fn) = VISIBILITY_INTERNAL;
+	  DECL_VISIBILITY_SPECIFIED (fn) = true;
+#endif
+	}
+      if (!TREE_PUBLIC (fn))
+	DECL_INTERFACE_KNOWN (fn) = true;
+      mark_used (fn);
+      note_vague_linkage_fn (fn);
+
+#if 0
+      /* We want CSE to commonize calls to the wrapper, but marking it as
+	 pure is unsafe since it has side-effects.  I guess we need a new
+	 ECF flag even weaker than ECF_PURE.  FIXME!  */
+      DECL_PURE_P (fn) = true;
+#endif
+
+      DECL_BEFRIENDING_CLASSES (fn) = var;
+
+      SET_IDENTIFIER_GLOBAL_VALUE (sname, fn);
+    }
+  return fn;
+}
+
+/* At EOF, generate the definition for the TLS wrapper function FN:
+
+   T& var_wrapper() {
+     if (init_fn) init_fn();
+     return var;
+   }  */
+
+static void
+generate_tls_wrapper (tree fn)
+{
+  tree var = DECL_BEFRIENDING_CLASSES (fn);
+
+  start_preparsed_function (fn, NULL_TREE, SF_DEFAULT | SF_PRE_PARSED);
+  tree body = begin_function_body ();
+  /* Only call the init fn if there might be one.  */
+  if (tree init_fn = get_tls_init_fn (var))
+    {
+      tree if_stmt = NULL_TREE;
+      /* If init_fn is a weakref, make sure it exists before calling.  */
+      if (lookup_attribute ("weak", DECL_ATTRIBUTES (init_fn)))
+	{
+	  if_stmt = begin_if_stmt ();
+	  tree addr = cp_build_addr_expr (init_fn, tf_warning_or_error);
+	  tree cond = cp_build_binary_op (DECL_SOURCE_LOCATION (var),
+					  NE_EXPR, addr, nullptr_node,
+					  tf_warning_or_error);
+	  finish_if_stmt_cond (cond, if_stmt);
+	}
+      finish_expr_stmt (build_cxx_call
+			(init_fn, 0, NULL, tf_warning_or_error));
+      if (if_stmt)
+	{
+	  finish_then_clause (if_stmt);
+	  finish_if_stmt (if_stmt);
+	}
+    }
+  finish_return_stmt (convert_from_reference (var));
+  finish_function_body (body);
+  expand_or_defer_fn (finish_function (0));
+}
+
 /* Start the process of running a particular set of global constructors
    or destructors.  Subroutine of do_[cd]tors.  */
 
@@ -3667,6 +3849,75 @@ clear_decl_external (struct cgraph_node *node, void * /*data*/)
   return false;
 }
 
+/* Build up the function to run dynamic initializers for thread_local
+   variables in this translation unit and alias the init functions for the
+   individual variables to it.  */
+
+static void
+handle_tls_init (void)
+{
+  tree vars = prune_vars_needing_no_initialization (&tls_aggregates);
+  if (vars == NULL_TREE)
+    return;
+
+  location_t loc = DECL_SOURCE_LOCATION (TREE_VALUE (vars));
+
+  #ifndef ASM_OUTPUT_DEF
+  /* This currently requires alias support.  FIXME other targets could use
+     small thunks instead of aliases.  */
+  input_location = loc;
+  sorry ("dynamic initialization of non-function-local thread_local "
+	 "variables not supported on this target");
+  return;
+  #endif
+
+  write_out_vars (vars);
+
+  tree guard = build_decl (loc, VAR_DECL, get_identifier ("__tls_guard"),
+			   boolean_type_node);
+  TREE_PUBLIC (guard) = false;
+  TREE_STATIC (guard) = true;
+  DECL_ARTIFICIAL (guard) = true;
+  DECL_IGNORED_P (guard) = true;
+  TREE_USED (guard) = true;
+  DECL_TLS_MODEL (guard) = decl_default_tls_model (guard);
+  pushdecl_top_level_and_finish (guard, NULL_TREE);
+
+  tree fn = build_lang_decl (FUNCTION_DECL,
+			     get_identifier ("__tls_init"),
+			     build_function_type (void_type_node,
+						  void_list_node));
+  SET_DECL_LANGUAGE (fn, lang_c);
+  TREE_PUBLIC (fn) = false;
+  DECL_ARTIFICIAL (fn) = true;
+  mark_used (fn);
+  start_preparsed_function (fn, NULL_TREE, SF_PRE_PARSED);
+  tree body = begin_function_body ();
+  tree if_stmt = begin_if_stmt ();
+  tree cond = cp_build_unary_op (TRUTH_NOT_EXPR, guard, false,
+				 tf_warning_or_error);
+  finish_if_stmt_cond (cond, if_stmt);
+  finish_expr_stmt (cp_build_modify_expr (guard, NOP_EXPR, boolean_true_node,
+					  tf_warning_or_error));
+  for (; vars; vars = TREE_CHAIN (vars))
+    {
+      tree var = TREE_VALUE (vars);
+      tree init = TREE_PURPOSE (vars);
+      one_static_initialization_or_destruction (var, init, true);
+
+      tree single_init_fn = get_tls_init_fn (var);
+      cgraph_node *alias
+	= cgraph_same_body_alias (cgraph_get_create_node (fn),
+				  single_init_fn, fn);
+      gcc_assert (alias != NULL);
+    }
+
+  finish_then_clause (if_stmt);
+  finish_if_stmt (if_stmt);
+  finish_function_body (body);
+  expand_or_defer_fn (finish_function (0));
+}
+
 /* This routine is called at the end of compilation.
    Its job is to create all the code needed to initialize and
    destroy the global aggregates.  We do the destruction
@@ -3844,6 +4095,9 @@ cp_write_global_declarations (void)
 	  /* ??? was:  locus.line++; */
 	}
 
+      /* Now do the same for thread_local variables.  */
+      handle_tls_init ();
+
       /* Go through the set of inline functions whose bodies have not
 	 been emitted yet.  If out-of-line copies of these functions
 	 are required, emit them.  */
@@ -3868,6 +4122,9 @@ cp_write_global_declarations (void)
 	      reconsider = true;
 	    }
 
+	  if (!DECL_INITIAL (decl) && decl_tls_wrapper_p (decl))
+	    generate_tls_wrapper (decl);
+
 	  if (!DECL_SAVED_TREE (decl))
 	    continue;