btf: add BTF_KIND_FUNC traversal function.

The patch adds a traversal function to traverse all BTF_KIND_FUNC nodes
with a callback function. Used for .BTF.ext section content creation.

gcc/ChangeLog:

	* btfout.cc (output_btf_func_types): Use FOR_EACH_VEC_ELT.
	(traverse_btf_func_types): Define function.
	* ctfc.h (funcs_traverse_callback): Typedef for function
	prototype.
	(traverse_btf_func_types): Add prototype.

Author: cupermir

gcc/btfout.cc

@@ -1276,8 +1276,10 @@ output_btf_types (ctf_container_ref ctfc)
 static void
 output_btf_func_types (ctf_container_ref ctfc)
 {
-  for (size_t i = 0; i < vec_safe_length (funcs); i++)
-    btf_asm_func_type (ctfc, (*funcs)[i], i);
+  ctf_dtdef_ref ref;
+  unsigned i;
+  FOR_EACH_VEC_ELT (*funcs, i, ref)
+    btf_asm_func_type (ctfc, ref, i);
 }
 
 /* Output all BTF_KIND_DATASEC records.  */
@@ -1452,4 +1454,20 @@ btf_finalize (void)
   tu_ctfc = NULL;
 }
 
+/* Traversal function for all BTF_KIND_FUNC type records.  */
+
+bool
+traverse_btf_func_types (funcs_traverse_callback callback, void *data)
+{
+  ctf_dtdef_ref ref;
+  unsigned i;
+  FOR_EACH_VEC_ELT (*funcs, i, ref)
+    {
+      bool stop = callback (ref, data);
+      if (stop == true)
+	return true;
+    }
+  return false;
+}
+
 #include "gt-btfout.h"

gcc/ctfc.h

@@ -441,6 +441,9 @@ extern int ctf_add_variable (ctf_container_ref, const char *, ctf_id_t,
 extern ctf_id_t ctf_lookup_tree_type (ctf_container_ref, const tree);
 extern ctf_id_t get_btf_id (ctf_id_t);
 
+typedef bool (*funcs_traverse_callback) (ctf_dtdef_ref, void *);
+bool traverse_btf_func_types (funcs_traverse_callback, void *);
+
 /* CTF section does not emit location information; at this time, location
    information is needed for BTF CO-RE use-cases.  */