Add condition to MUST_NOT_THROW_EXPR.

	gcc/cp/
	* cp-tree.def (MUST_NOT_THROW_EXPR): Add condition parameter.
	* cp-tree.h (MUST_NOT_THROW_COND): New.
	(build_must_not_throw_expr): Declare.
	* dump.c (cp_dump_tree): Dump MUST_NOT_THROW_EXPR condition.
	* except.c (build_must_not_throw_expr): New.
	(initialize_handler_parm): Use it.
	(begin_eh_spec_block, wrap_cleanups_r): Adapt to condition.
	* pt.c (tsubst_expr): Handle MUST_NOT_THROW_EXPR.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@182233 138bc75d-0d04-0410-961f-82ee72b054a4

6 files changed, 52 insertions, 5 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 1ba9f347a17..d553dce240e 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,14 @@
+2011-12-12  Torvald Riegel  <triegel@redhat.com>
+
+	* cp-tree.def (MUST_NOT_THROW_EXPR): Add condition parameter.
+	* cp-tree.h (MUST_NOT_THROW_COND): New.
+	(build_must_not_throw_expr): Declare.
+	* dump.c (cp_dump_tree): Dump MUST_NOT_THROW_EXPR condition.
+	* except.c (build_must_not_throw_expr): New.
+	(initialize_handler_parm): Use it.
+	(begin_eh_spec_block, wrap_cleanups_r): Adapt to condition.
+	* pt.c (tsubst_expr): Handle MUST_NOT_THROW_EXPR.
+
 2011-12-12  Richard Guenther  <rguenther@suse.de>
 
 	PR lto/51262
diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def
index 5fc5496ef9e..83e0b5baab6 100644
--- a/gcc/cp/cp-tree.def
+++ b/gcc/cp/cp-tree.def
@@ -281,8 +281,9 @@ DEFTREECODE (EH_SPEC_BLOCK, "eh_spec_block", tcc_statement, 2)
 DEFTREECODE (HANDLER, "handler", tcc_statement, 2)
 
 /* A MUST_NOT_THROW_EXPR wraps an expression that may not
-   throw, and must call terminate if it does.  */
-DEFTREECODE (MUST_NOT_THROW_EXPR, "must_not_throw_expr", tcc_expression, 1)
+   throw, and must call terminate if it does.  The second argument
+   is a condition, used in templates to express noexcept (condition).  */
+DEFTREECODE (MUST_NOT_THROW_EXPR, "must_not_throw_expr", tcc_expression, 2)
 
 /* A CLEANUP_STMT marks the point at which a declaration is fully
    constructed.  The CLEANUP_EXPR is run on behalf of CLEANUP_DECL
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 955d0eb3668..c28b2297486 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -3016,6 +3016,11 @@ more_aggr_init_expr_args_p (const aggr_init_expr_arg_iterator *iter)
 #define VEC_INIT_EXPR_VALUE_INIT(NODE) \
   TREE_LANG_FLAG_1 (VEC_INIT_EXPR_CHECK (NODE))
 
+/* The condition under which this MUST_NOT_THROW_EXPR actually blocks
+   exceptions.  NULL_TREE means 'true'.  */
+#define MUST_NOT_THROW_COND(NODE) \
+  TREE_OPERAND (MUST_NOT_THROW_EXPR_CHECK (NODE), 1)
+
 /* The TYPE_MAIN_DECL for a class template type is a TYPE_DECL, not a
    TEMPLATE_DECL.  This macro determines whether or not a given class
    type is really a template type, as opposed to an instantiation or
@@ -5148,6 +5153,7 @@ extern bool type_noexcept_p			(const_tree);
 extern bool type_throw_all_p			(const_tree);
 extern tree build_noexcept_spec			(tree, int);
 extern void choose_personality_routine		(enum languages);
+extern tree build_must_not_throw_expr		(tree,tree);
 extern tree eh_type_info			(tree);
 extern tree begin_eh_spec_block			(void);
 extern void finish_eh_spec_block		(tree, tree);
diff --git a/gcc/cp/dump.c b/gcc/cp/dump.c
index d1631fc35cd..a461094f504 100644
--- a/gcc/cp/dump.c
+++ b/gcc/cp/dump.c
@@ -413,6 +413,7 @@ cp_dump_tree (void* dump_info, tree t)
     case MUST_NOT_THROW_EXPR:
       dump_stmt (di, t);
       dump_child ("body", TREE_OPERAND (t, 0));
+      dump_child ("cond", MUST_NOT_THROW_COND (t));
       break;
 
     case USING_STMT:
diff --git a/gcc/cp/except.c b/gcc/cp/except.c
index 670a66f1611..c56dc2c734b 100644
--- a/gcc/cp/except.c
+++ b/gcc/cp/except.c
@@ -374,6 +374,28 @@ choose_personality_routine (enum languages lang)
   state = gave_error;
 }
 
+/* Wrap EXPR in a MUST_NOT_THROW_EXPR expressing that EXPR must
+   not throw any exceptions if COND is true.  A condition of
+   NULL_TREE is treated as 'true'.  */
+
+tree
+build_must_not_throw_expr (tree body, tree cond)
+{
+  tree type = body ? TREE_TYPE (body) : void_type_node;
+
+  if (cond && !value_dependent_expression_p (cond))
+    {
+      cond = cxx_constant_value (cond);
+      if (integer_zerop (cond))
+	return body;
+      else if (integer_onep (cond))
+	cond = NULL_TREE;
+    }
+
+  return build2 (MUST_NOT_THROW_EXPR, type, body, cond);
+}
+
+
 /* Initialize the catch parameter DECL.  */
 
 static void
@@ -418,7 +440,7 @@ initialize_handler_parm (tree decl, tree exp)
       /* Force cleanups now to avoid nesting problems with the
 	 MUST_NOT_THROW_EXPR.  */
       init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
-      init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
+      init = build_must_not_throw_expr (init, NULL_TREE);
     }
 
   decl = pushdecl (decl);
@@ -560,7 +582,8 @@ begin_eh_spec_block (void)
      MUST_NOT_THROW_EXPR.  */
   if (TYPE_NOEXCEPT_P (TREE_TYPE (current_function_decl)))
     {
-      r = build_stmt (spec_location, MUST_NOT_THROW_EXPR, NULL_TREE);
+      r = build_stmt (spec_location, MUST_NOT_THROW_EXPR,
+		      NULL_TREE, NULL_TREE);
       TREE_SIDE_EFFECTS (r) = 1;
     }
   else
@@ -664,7 +687,8 @@ wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
   cleanup = TARGET_EXPR_CLEANUP (exp);
   if (cleanup)
     {
-      cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
+      cleanup = build2 (MUST_NOT_THROW_EXPR, void_type_node, cleanup,
+			NULL_TREE);
       TARGET_EXPR_CLEANUP (exp) = cleanup;
     }
 
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index bb5aa0c1484..f5a31752506 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13260,6 +13260,10 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
       }
       break;
 
+    case MUST_NOT_THROW_EXPR:
+      return build_must_not_throw_expr (RECUR (TREE_OPERAND (t, 0)),
+					RECUR (MUST_NOT_THROW_COND (t)));
+
     case EXPR_PACK_EXPANSION:
       error ("invalid use of pack expansion expression");
       return error_mark_node;