We describe the SPACE algorithm for translating from one architecture such as PowerPC into
operations for another architecture such as VLIW, while also supporting scheduling, register allocation,
and other optimizations. Our SPACE algorithm supports precise exceptions, but in an
improvement over our previous work, eliminates the need for most hardware register commit operations, which are used to place values in their original program location in the original program
sequence. The elimination of commit operations frees issue slots for other computation, a feature
that is especially important for narrower machines. The SPACE algorithm is efficient, running in
O(N2) time in the number N of operations in the worst case, but in practice is closer to a two-pass
O(N) algorithm.
The fact that our approach provides precise exceptions with low overhead is useful to programming
language designers as well — exception models in which an exception can occur at almost
any instruction are not prohibitively expensive.
By: Erik R. Altman, Kemal Ebcioglu, Michael Gschwind, Sumedh Sathaye
Published in: RC22957 in 1999
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