Change format of global.set to not use the unifies property

The global.set node now produces a 'get' after the 'set'. This leads to a more concise and traceable effect on the stack

wasmlike/wasmlike.rkt

@@ -158,9 +158,8 @@
             #:prop reference-info (read name)
             #:prop choice-weight 4] 
  [GlobalSet Expr ([val : Expr]
-                  [name]
-                  [expr : Expr])
-            #:prop reference-info (write name #:unifies val)
+                  [name])
+            #:prop reference-info (write name)
             #:prop choice-weight 4]
 
  ;; Type conversions
@@ -213,8 +212,7 @@
   [ForLoop (hash 'loopvar (make-fresh-node 
                             'GlobalSet
                             (hash 'val (make-fresh-node 'LiteralIntThirtyTwo) ;;dummy
-                                  'name (binding-name (send this xsmith_get-reference-for-child! i32 #t))
-                                  'expr (make-fresh-node 'LiteralIntThirtyTwo))))] ;;dummy
+                                  'name (binding-name (send this xsmith_get-reference-for-child! i32 #t)))))]
 )
 
 (add-att-rule
@@ -336,8 +334,7 @@
                                         'expr i32))]]
           [LocalTee [i32 (λ (n t) (hash 'val i32))]]
           [GlobalGet [(number) (no-child-types)]]
-          [GlobalSet [(number) (λ (n t) (hash 'val t
-                                              'expr t))]]
+          [GlobalSet [(number) (λ (n t) (hash 'val t))]]
           ;;Type conversions
           [TruncateFloat [(int) 
                      (λ (n t) 
@@ -583,7 +580,7 @@
                (append
                  ($xsmith_render-node (ast-child 'val n))
                  `(global.set ,(string->symbol (format "$~a" (ast-child 'name n))))
-                 ($xsmith_render-node (ast-child 'expr n))))]
+                 `(global.get ,(string->symbol (format "$~a" (ast-child 'name n))))))]
  [TruncateFloat (λ (n)
                    (append
                      ($xsmith_render-node (ast-child 'expr n))