diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index c4eb2b1c920..681fcc972f4 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -3375,7 +3375,6 @@ pointer_int_sum (location_t loc, enum tree_code resultcode,
 tree
 c_wrap_maybe_const (tree expr, bool non_const)
 {
-  bool nowarning = TREE_NO_WARNING (expr);
   location_t loc = EXPR_LOCATION (expr);
 
   /* This should never be called for C++.  */
@@ -3386,8 +3385,6 @@ c_wrap_maybe_const (tree expr, bool non_const)
   STRIP_TYPE_NOPS (expr);
   expr = build2 (C_MAYBE_CONST_EXPR, TREE_TYPE (expr), NULL, expr);
   C_MAYBE_CONST_EXPR_NON_CONST (expr) = non_const;
-  if (nowarning)
-    TREE_NO_WARNING (expr) = 1;
   protected_set_expr_location (expr, loc);
 
   return expr;
@@ -3633,12 +3630,12 @@ c_common_truthvalue_conversion (location_t location, tree expr)
       break;
 
     case MODIFY_EXPR:
-      if (!TREE_NO_WARNING (expr)
+      if (!warning_suppressed_p (expr, OPT_Wparentheses)
 	  && warn_parentheses
 	  && warning_at (location, OPT_Wparentheses,
 			 "suggest parentheses around assignment used as "
 			 "truth value"))
-	TREE_NO_WARNING (expr) = 1;
+	suppress_warning (expr, OPT_Wparentheses);
       break;
 
     case CONST_DECL:
@@ -6019,7 +6016,7 @@ check_function_arguments_recurse (void (*callback)
 				  void *ctx, tree param,
 				  unsigned HOST_WIDE_INT param_num)
 {
-  if (TREE_NO_WARNING (param))
+  if (warning_suppressed_p (param))
     return;
 
   if (CONVERT_EXPR_P (param)
diff --git a/gcc/c-family/c-gimplify.c b/gcc/c-family/c-gimplify.c
index 39c969d8f40..0d38b706f4c 100644
--- a/gcc/c-family/c-gimplify.c
+++ b/gcc/c-family/c-gimplify.c
@@ -713,7 +713,7 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED,
 	  && !TREE_STATIC (DECL_EXPR_DECL (*expr_p))
 	  && (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) == DECL_EXPR_DECL (*expr_p))
 	  && !warn_init_self)
-	TREE_NO_WARNING (DECL_EXPR_DECL (*expr_p)) = 1;
+	suppress_warning (DECL_EXPR_DECL (*expr_p), OPT_Winit_self);
       break;
 
     case PREINCREMENT_EXPR:
diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c
index cd3c99ef4df..34959590b37 100644
--- a/gcc/c-family/c-warn.c
+++ b/gcc/c-family/c-warn.c
@@ -155,7 +155,7 @@ overflow_warning (location_t loc, tree value, tree expr)
 			 value);
 
   if (warned)
-    TREE_NO_WARNING (value) = 1;
+    suppress_warning (value, OPT_Woverflow);
 }
 
 /* Helper function for walk_tree.  Unwrap C_MAYBE_CONST_EXPRs in an expression
@@ -219,7 +219,7 @@ warn_logical_operator (location_t location, enum tree_code code, tree type,
       && INTEGRAL_TYPE_P (TREE_TYPE (op_left))
       && !CONSTANT_CLASS_P (stripped_op_left)
       && TREE_CODE (stripped_op_left) != CONST_DECL
-      && !TREE_NO_WARNING (op_left)
+      && !warning_suppressed_p (op_left, OPT_Wlogical_op)
       && TREE_CODE (op_right) == INTEGER_CST
       && !integer_zerop (op_right)
       && !integer_onep (op_right))
@@ -234,7 +234,7 @@ warn_logical_operator (location_t location, enum tree_code code, tree type,
 	  = warning_at (location, OPT_Wlogical_op,
 			"logical %<and%> applied to non-boolean constant");
       if (warned)
-	TREE_NO_WARNING (op_left) = true;
+	suppress_warning (op_left, OPT_Wlogical_op);
       return;
     }
 
@@ -588,7 +588,7 @@ bool
 warn_if_unused_value (const_tree exp, location_t locus, bool quiet)
 {
  restart:
-  if (TREE_USED (exp) || TREE_NO_WARNING (exp))
+  if (TREE_USED (exp) || warning_suppressed_p (exp, OPT_Wunused_value))
     return false;
 
   /* Don't warn about void constructs.  This includes casting to void,
@@ -2410,7 +2410,7 @@ do_warn_unused_parameter (tree fn)
        decl; decl = DECL_CHAIN (decl))
     if (!TREE_USED (decl) && TREE_CODE (decl) == PARM_DECL
 	&& DECL_NAME (decl) && !DECL_ARTIFICIAL (decl)
-	&& !TREE_NO_WARNING (decl))
+	&& !warning_suppressed_p (decl, OPT_Wunused_parameter))
       warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wunused_parameter,
 		  "unused parameter %qD", decl);
 }