Task Static Single Assignment (T-SSA) and Its Use in Safe Program Parallelization (short paper)

The mechanism of copy-on-write is recently used in speculative and deterministic parallel systems. In these systems, copy-on-write happens when a task modifies a variable for the first time. At the program level, the copying is a form of renaming. This paper extends the formalism of static single assignment (SSA) to introduce a program representation called task static single assignment (T-SSA). The new representation integrates the copy-on-write renaming across tasks with the conventional SSA renaming within a task. This position paper defines the T-SSA form and demonstrates its use in making copy-on-write explicit, automatic, and automatically enhanced for safe program parallelization.