anchor.diff:                          ,@(unless operands
                               `((declare (ignore args))))
                           ,@(loop for cap in required-capabilities
  -                                collect `(assert (gethash ',cap *enabled-caps*)))
  +                                collect `(check-cap ,cap))
                           (with-spirv-instruction (,ext-inst)
                             (asm-type type)
                             (asm-id dest)
  
positive.code: (defvar *current-section*) ;; bind to 1
  ;; just for debugging
  (defvar *current-form* nil)
  (defvar *id-conflicts*)
  
  (defmacro with-ll-asm-context (() &body body)
    `(let ((*next-id* 0)
  
negative.code:            (spirv-core:store i %62)
             (spirv-core:branch @49)      ; loop back
             (spirv-core:label @51)       ; loop merge point
             ;; something with caps :
             ;;(spirv-core:bit-reverse %70 :int32 %54)
             ;; something with unspecified caps :
             ;;(spirv-core:dp-dx-fine %70 :float32 %54)
             (spirv-core:return)
             (spirv-core:function-end)))))
    (with-open-file (f "/tmp/example.spv"
  