Section: Software and Platforms

Bee

Participants : Christophe Alias, Alain Darte.

Bee is a source-to-source optimizer that contracts the temporary arrays of a program under scheduling constraints. Bee bridges the gap between the mathematical optimization framework described in  [17] and implemented in Cl@k (Section  5.4 ), and effective source-to-source array contraction. Bee applies a precise lifetime analysis for arrays to build the mathematical input of Cl@k. Then, Bee derives the array allocations from the basis found by Cl@k and generates the C code accordingly. Bee is – to our knowledge – the only complete array contraction tool.

Bee is sensitive to the program schedule. This latter feature enlarges the application field of array contraction to parallel programs. For instance, it is possible to mark a loop to be software-pipelined (with an affine schedule) and to let Bee find an optimized array contraction. But the most important application is the ability to optimize communicating regular processes (CRP). Given a schedule for every process, Bee can compute an optimized size for the channels, together with their access functions (the corresponding allocations). We currently use this feature in source-to-source transformations for high-level synthesis (see Section  3.3 ).

• Bee was made available to STMicroelectronics as a binary.

• Bee has been transferred to the (incubated) start-up Zettice, initiated by Alexandru Plesco.

• Bee has been used as an external tool by the compiler Gecos developed in the Cairn team at Irisa.

Bee has been implemented by Christophe Alias, using the compiler infrastructure PoCo (see Section  5.5 ). It represents more than 2400 lines of C++ code.