// big stack arguments frame.
	args unsafe.Pointer
	// Below are out-args from callbackWrap
	result uintptr
	retPop uintptr // For 386 cdecl, how many bytes to pop on return
}

// callbackWrap is called by callbackasm to invoke a registered C callback.
func callbackWrap(a *callbackArgs) {
	c := cbs.ctxt[a.index]
	a.retPop = c.retPop

	// Convert from C to Go ABI.

// these pointers in regArgs.Ptrs such that they are visible to the GC.
//
// Package reflect passes a frame type. In package runtime, there is only
// one call that copies results back, in callbackWrap in syscall_windows.go, and it
// does NOT pass a frame type, meaning there are no write barriers invoked. See that
// call site for justification.
//
// Package reflect accesses this symbol through a linkname.
//