VM_ENVVAL_BLOCK_PTR_FLAG  962 vm_core.h      #define VM_ENVVAL_BLOCK_PTR(v)     (GC_GUARDED_PTR(v) | VM_ENVVAL_BLOCK_PTR_FLAG)
VM_ENVVAL_BLOCK_PTR_FLAG  963 vm_core.h      #define VM_ENVVAL_BLOCK_PTR_P(v)   ((v) & VM_ENVVAL_BLOCK_PTR_FLAG)