One embodiment of the present invention provides a system that facilitates entering and exiting a critical section of code for a speculative thread. The system supports a head thread that executes program instructions, and the speculative thread that speculatively executes program instructions in advance of the head thread. During an entry into the critical section by the speculative thread, the system increments a variable containing a number of virtual locks held by the speculative thread. Note that a virtual lock held by the speculative thread is associated with the critical section and is used to keep track of the fact that the speculative thread has entered the critical section. Also note that this virtual lock does not prevent the speculative thread or other threads from entering the critical section. During an exit from the critical section by the speculative thread, the system decrements the variable containing the number of virtual locks held by the speculative thread. The speculative eventually receives a request to perform a join operation with the head thread to merge state associated with the speculative thread into state associated with the head thread. Upon receiving this request, the speculative thread waits to perform the join operation until the variable containing the number of virtual locks held by the speculative thread equals zero. In one embodiment of the present invention, the system additionally waits to perform the join operation until no virtual locks in a list of virtual locks accessed by the speculative thread are held by the other head threads.