markBranch
markBranch(dictionary, vm, leaveTag);
markBranch(dictionary, vm, doTag);
markBranch(dictionary, vm, leaveTag);
markBranch(dictionary, vm, doTag);
markBranch(dictionary, vm, destTag);
markBranch(dictionary, vm, origTag);
markBranch(dictionary, vm, origTag);
markBranch(dictionary, vm, origTag); /* (4) push "else" patch addr */
markBranch(dictionary, vm, ofTag);