add an impl of prepargs, which mustn't actually be used yet

need to implement the rest of function invocation first, i.e.
arg_* and invoke_*.

src/jit/core.expr

@@ -19,6 +19,8 @@
 (macro: ^cu_string (,a) (idx  (^getf (cu) MVMCompUnit body.strings) ,a ptr_sz))
 (template: const_s (load (^cu_string $1) ptr_sz))
 
+(macro: ^cu_callsite (,a) (idx  (^getf (cu) MVMCompUnit body.callsites) ,a ptr_sz))
+
 (template: set (copy $1))
 (template: getlex (copy $1))
 (template: bindlex (store $0 $1 reg_sz))
@@ -103,6 +105,12 @@
                            $replace
                            (addr ,a (&offsetof MVMP6opaque body)))))
 
+# since compilation of invocation is special-cased in the regular jit
+# we can't just toss this in here without also handling all of arg_*
+# and invoke_*.
+#(template: prepargs (^setf (^getf (tc) MVMThreadContext cur_frame) MVMFrame cur_args_callsite
+                           #(^cu_callsite $0))))
+
 (template: sp_p6oget_i (load (add (^p6obody $1) $2) int_sz))
 (template: sp_p6oget_n (load (add (^p6obody $1) $2) (&sizeof MVMnum64)))
 (template: sp_p6oget_s (load (add (^p6obody $1) $2) ptr_sz))

src/jit/expr.c

@@ -186,6 +186,10 @@ static MVMint32 MVM_jit_expr_add_const(MVMThreadContext *tc, MVMJitExprTree *tre
         template[1] = MVM_jit_label_before_bb(tc, tree->graph, opr.ins_bb);
         template[2] = sizeof(MVMint32);
         break;
+    case MVM_operand_callsite:
+        template[1] = opr.callsite_idx;
+        template[2] = sizeof(MVMuint16);
+        break;
     case MVM_operand_spesh_slot:
         template[1] = opr.lit_i16;
         template[2] = sizeof(MVMuint16);