must_tail_call_attribute_plugin.patch

diff --git a/gcc/testsuite/gcc.dg/plugin/must-tail-call-1.c b/gcc/testsuite/gcc.dg/plugin/must-tail-call-1.c
index 1495a4823..d01e4645f 100644
--- a/gcc/testsuite/gcc.dg/plugin/must-tail-call-1.c
+++ b/gcc/testsuite/gcc.dg/plugin/must-tail-call-1.c
@@ -1,5 +1,11 @@
 /* { dg-options "-fdelayed-branch" { target sparc*-*-* } } */
 
+#if __has_attribute (musttail)
+#  define MUSTTAIL __attribute__((noinline,noclone,musttail))
+#else
+#  define MUSTTAIL __attribute__((noinline,noclone))
+#endif
+
 extern void abort (void);
 
 int __attribute__((noinline,noclone))
@@ -8,7 +14,7 @@ callee (int i)
   return i * i;
 }
 
-int __attribute__((noinline,noclone))
+int MUSTTAIL
 caller (int i)
 {
   return callee (i + 1);
diff --git a/gcc/testsuite/gcc.dg/plugin/must-tail-call-2.c b/gcc/testsuite/gcc.dg/plugin/must-tail-call-2.c
index c6dfecd32..9f61bbf58 100644
--- a/gcc/testsuite/gcc.dg/plugin/must-tail-call-2.c
+++ b/gcc/testsuite/gcc.dg/plugin/must-tail-call-2.c
@@ -1,6 +1,14 @@
 /* Allow nested functions.  */
 /* { dg-options "-Wno-pedantic" } */
 
+#if __has_attribute (musttail)
+#  define NOINLINE_MUSTTAIL __attribute__((noinline,noclone,musttail))
+#  define MUSTTAIL __attribute__((musttail))
+#else
+#  define NOINLINE_MUSTTAIL __attribute__((noinline,noclone))
+#  define MUSTTAIL
+#endif
+
 struct box { char field[64]; int i; };
 
 struct box __attribute__((noinline,noclone))
@@ -11,13 +19,13 @@ returns_struct (int i)
   return b;
 }
 
-int __attribute__((noinline,noclone))
+int NOINLINE_MUSTTAIL
 test_1 (int i)
 {
   return returns_struct (i * 5).i; /* { dg-error "cannot tail-call: " } */
 }
 
-int __attribute__((noinline,noclone))
+int NOINLINE_MUSTTAIL
 test_2_callee (int i, struct box b)
 {
   if (b.field[0])
@@ -25,7 +33,7 @@ test_2_callee (int i, struct box b)
   return i * i;
 }
 
-int __attribute__((noinline,noclone))
+int NOINLINE_MUSTTAIL
 test_2_caller (int i)
 {
   struct box b;
@@ -33,13 +41,14 @@ test_2_caller (int i)
 }
 
 extern void setjmp (void);
-void
+
+void MUSTTAIL
 test_3 (void)
 {
   setjmp (); /* { dg-error "cannot tail-call: " } */
 }
 
-void
+void MUSTTAIL
 test_4 (void)
 {
   void nested (void)
@@ -51,7 +60,7 @@ test_4 (void)
 typedef void (fn_ptr_t) (void);
 volatile fn_ptr_t fn_ptr;
 
-void
+void MUSTTAIL
 test_5 (void)
 {
   fn_ptr (); /* { dg-error "cannot tail-call: " } */
diff --git a/gcc/testsuite/gcc.dg/plugin/must_tail_call_attribute_plugin.c b/gcc/testsuite/gcc.dg/plugin/must_tail_call_attribute_plugin.c
new file mode 100644
index 000000000..d237aba1d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/plugin/must_tail_call_attribute_plugin.c
@@ -0,0 +1,86 @@
+#include "gcc-plugin.h"
+#include "plugin-version.h"
+#include "tree.h"
+#include "stringpool.h"
+#include "attribs.h"
+#include "print-tree.h"
+
+int plugin_is_GPL_compatible;
+
+static struct plugin_info musttail_plugin_info = {
+  .version = "0.0.1",
+  .help = "Provides musttail attribute\n",
+};
+
+static struct attribute_spec musttail_attr = {
+  .name = "musttail",
+  .min_length = 0,
+  .max_length = 0,
+  .decl_required = true,
+  .type_required = false,
+  .function_type_required = false,
+  .affects_type_identity = false,
+  .handler = NULL,
+  .exclude = NULL,
+};
+
+static void
+register_attributes (void *event_data ATTRIBUTE_UNUSED,
+                    void *data ATTRIBUTE_UNUSED)
+{
+  register_attribute (&musttail_attr);
+}
+
+tree
+cb_walk_tree_fn (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
+                void *data ATTRIBUTE_UNUSED)
+{
+  if (TREE_CODE (*tp) != CALL_EXPR)
+    return NULL_TREE;
+
+  tree call_expr = *tp;
+
+  CALL_EXPR_MUST_TAIL_CALL (call_expr) = 1;
+
+  return NULL_TREE;
+}
+
+static void