[gcc(refs/users/dfaust/heads/btf-type-tag-new-rebase)] c-family: Add BTF tag attribute handlers

[gcc(refs/users/dfaust/heads/btf-type-tag-new-rebase)] c-family: Add BTF tag attribute handlers

[David Faust]

https://gcc.gnu.org/g:4587fe84d9fed5eb7f0ea58784ec04f878ea5312

commit 4587fe84d9fed5eb7f0ea58784ec04f878ea5312
Author: David Faust <david.faust@oracle.com>
Date:   Wed Mar 2 15:01:58 2022 -0800

    c-family: Add BTF tag attribute handlers
    
    This patch adds attribute handlers in GCC for two attributes already
    supported in LLVM: "btf_decl_tag" and "btf_type_tag". Both attributes
    accept a single string constant argument, and are used to add arbitrary
    annotations to debug information generated for the types/decls to which
    they apply.
    
    gcc/c-family/
    
            * c-attribs.cc (c_common_attribute_table): Add new attributes
            btf_decl_tag and btf_type_tag.
            (handle_btf_decl_tag_attribute): New.
            (handle_btf_type_tag_attribute): Likewise.

Diff:
---
 gcc/c-family/c-attribs.cc | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index 671ea38fd1b..346d8dc8a81 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -176,6 +176,9 @@ static tree handle_signed_bool_precision_attribute (tree *, tree, tree, int,
 static tree handle_retain_attribute (tree *, tree, tree, int, bool *);
 static tree handle_fd_arg_attribute (tree *, tree, tree, int, bool *);
 
+static tree handle_btf_decl_tag_attribute (tree *, tree, tree, int, bool *);
+static tree handle_btf_type_tag_attribute (tree *, tree, tree, int, bool *);
+
 /* Helper to define attribute exclusions.  */
 #define ATTR_EXCL(name, function, type, variable)	\
   { name, function, type, variable }
@@ -565,6 +568,12 @@ const struct attribute_spec c_common_attribute_table[] =
             handle_fd_arg_attribute, NULL},
   { "fd_arg_write",       1, 1, false, true, true, false,
             handle_fd_arg_attribute, NULL},         
+
+  { "btf_type_tag",           1, 1, false, true, false, false,
+			      handle_btf_type_tag_attribute, NULL },
+  { "btf_decl_tag",           1, 1, false, false, false, false,
+			      handle_btf_decl_tag_attribute, NULL },
+
   { NULL,                     0, 0, false, false, false, false, NULL, NULL }
 };
 
@@ -5921,6 +5930,42 @@ handle_tainted_args_attribute (tree *node, tree name, tree, int,
   return NULL_TREE;
 }
 
+/* Handle a "btf_decl_tag" attribute; arguments as in
+   struct attribute_spec.handler.   */
+
+static tree
+handle_btf_decl_tag_attribute (tree *, tree name, tree args, int,
+			       bool *no_add_attrs)
+{
+  if (!args)
+    *no_add_attrs = true;
+  else if (TREE_CODE (TREE_VALUE (args)) != STRING_CST)
+    {
+      error ("%qE attribute requires a string", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
+/* Handle a "btf_type_tag" attribute; arguments as in
+   struct attribute_spec.handler.   */
+
+static tree
+handle_btf_type_tag_attribute (tree *, tree name, tree args, int,
+			       bool *no_add_attrs)
+{
+  if (!args)
+    *no_add_attrs = true;
+  else if (TREE_CODE (TREE_VALUE (args)) != STRING_CST)
+    {
+      error ("%qE attribute requires a string", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
 /* Attempt to partially validate a single attribute ATTR as if
    it were to be applied to an entity OPER.  */