p6/SPRAC Design (3)

• Object format: mutex + abstract state (bit vector).
  
  • State condition --- represented as bit-masks. Handed by the caller in registers (paired with each argument registers).
  • State checking --- performed at each method entry. Obtains object locks (in ascending address order) and apply bit-masks one by one.
  • If satisfied, release locks and proceed.
  • If unsatisfied, current context is saved to frame and control returns to the caller. Cascaded suspension occurs as necessary (same as in StackThreads[Taura et. al.]).