[lang] add a tree type that represents an FFI closure

We will be using FFI closures for allowing function pointers to be created. Add
a tree type that allows us to track the use of FFI allocated memory and GC it
when needed.

src/c.lang

@@ -6,6 +6,8 @@
   (ptr "void *")
   (sz "size_t")
   (flag "bool")
+  (ffi_cif "ffi_cif *")
+  (ffi_closure "ffi_closure *")
   (comp_decl_type "compound_type")
   (live_var_val "union value *"))
 
@@ -184,6 +186,11 @@
 (deftype T_FN_CALL "Function Call" "tFNCALL"
          ("ID" "ARGS"))
 
+(deftype T_CLOSURE "Closure Call" "tCLOSURE"
+         ("ARG_TYPES" "RET_TYPE" "FN"
+          ("CIF" ffi_cif)
+          ("CLOSURE" ffi_closure)))
+
 (deftype T_FN_ARG "Function Argument" "tFNARG"
          ("EXP"))
 

src/gc.c

@@ -101,6 +101,10 @@ static void dealloc_object(gc_obj obj)
     case E_ALLOC:
         free(tALLOC_PTR(t));
         break;
+    case T_CLOSURE:
+        ffi_closure_free(tCLOSURE_CLOSURE(t));
+        free(tCLOSURE_CIF(t));
+        break;
     default:
         /* All other types don't contain any other referencies to
          * dynamic memory. */

src/tree-dump-primitives.h

@@ -68,6 +68,17 @@ static inline void tree_dump_integer(tree t, mpz_t val, enum DUMP_TYPE dt)
     gmp_fprintf(stderr, "%Zd", val);
 }
 
+static inline void tree_dump_ffi_closure(tree t, ffi_closure *closure, enum DUMP_TYPE dt)
+{
+    return;
+}
+
+static inline void tree_dump_ffi_cif(tree t, ffi_cif *closure,
+                                         enum DUMP_TYPE dt)
+{
+    return;
+}
+
 static inline void tree_dump_comp_decl_type(tree t, compound_type v, enum DUMP_TYPE dt)
 {
     switch(v) {

src/tree.h

@@ -8,6 +8,7 @@
 #include <string.h>
 #include <stdbool.h>
 #include <setjmp.h>
+#include <ffi.h>
 #include "list.h"
 #include "tree-access.h"