[gcc r15-2168] Add a musttail generic attribute to the c-attribs table

[Andi Kleen via Gcc-cvs]

https://gcc.gnu.org/g:5c4c1fe6df0f752764cdfd7404a60bfd2b4f5057

commit r15-2168-g5c4c1fe6df0f752764cdfd7404a60bfd2b4f5057
Author: Andi Kleen <a...@linux.intel.com>
Date:   Wed May 15 19:38:43 2024 -0700

    Add a musttail generic attribute to the c-attribs table
    
    The actual handling is directly in the parser since the
    generic mechanism doesn't support statement attributes,
    but this gives basic error checking/detection on the attribute.
    
    gcc/c-family/ChangeLog:
    
            PR c/83324
            * c-attribs.cc (handle_musttail_attribute): Add.
            * c-common.h (handle_musttail_attribute): Add.

Diff:
---
 gcc/c-family/c-attribs.cc | 15 +++++++++++++++
 gcc/c-family/c-common.h   |  1 +
 2 files changed, 16 insertions(+)

diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index f9b229aba7fc..5adc7b775eaf 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -340,6 +340,8 @@ const struct attribute_spec c_common_gnu_attributes[] =
   { "common",                 0, 0, true,  false, false, false,
                              handle_common_attribute,
                              attr_common_exclusions },
+  { "musttail",                      0, 0, false, false, false,
+                             false, handle_musttail_attribute, NULL },
   /* FIXME: logically, noreturn attributes should be listed as
      "false, true, true" and apply to function types.  But implementing this
      would require all the places in the compiler that use TREE_THIS_VOLATILE
@@ -1222,6 +1224,19 @@ handle_common_attribute (tree *node, tree name, tree 
ARG_UNUSED (args),
   return NULL_TREE;
 }
 
+/* Handle a "musttail" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+tree
+handle_musttail_attribute (tree ARG_UNUSED (*node), tree name, tree ARG_UNUSED 
(args),
+                          int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+  /* Currently only a statement attribute, handled directly in parser.  */
+  warning (OPT_Wattributes, "%qE attribute ignored", name);
+  *no_add_attrs = true;
+  return NULL_TREE;
+}
+
 /* Handle a "noreturn" attribute; arguments as in
    struct attribute_spec.handler.  */
 
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index ccaea27c2b9f..adee822a3ae0 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1645,6 +1645,7 @@ extern tree find_tm_attribute (tree);
 extern const struct attribute_spec::exclusions attr_cold_hot_exclusions[];
 extern const struct attribute_spec::exclusions attr_noreturn_exclusions[];
 extern tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
+extern tree handle_musttail_attribute (tree *, tree, tree, int, bool *);
 extern bool has_attribute (location_t, tree, tree, tree (*)(tree));
 extern tree build_attr_access_from_parms (tree, bool);