Fix primitive arguments to upcalls not compiling

CHANGELOG.md

@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This change
 
 ## [Unreleased]
 ### Fixed
+- Primitive-serializing types fail to load as arguments to upcall functions
 - Void return types on upcalls crash the JVM
 - Invalid implementation of serialize-into for primitive types
 

src/clj/coffi/ffi.clj

@@ -320,7 +320,7 @@
                      [:getfield :this "upcall_ifn" IFn]
                      (map-indexed
                       (fn [idx arg]
-                        [[(load-instructions arg :aload) (inc idx)]
+                        [[(load-instructions (mem/primitive-type arg) :aload) (inc idx)]
                          (to-object-asm arg)])
                       arg-types)
                      [:invokeinterface IFn "invoke" (repeat (inc (count arg-types)) Object)]