1. Building a Program Generator With Scala
Georg Ofenbeck
Markus Püschel
Computer Science
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2. Goal Building a prototypical program generator inside Scala
“Spiral like”
Support for
Domain specific languages (algorithm representation)
Rewriting (on DSL for structural optimization)
Compilation ( DSL, → DSL2, → …. → C)

3. DSL in Scala: SPL Lightweight Modular Staging [1]
F_2 tensor I(4)
Rep[F_2] tensor Rep[I(4)]
Rep[+T] abstract type constructor
Tensor (Exp[F_2], Exp[I(4)])
Symbol X
Tensor (Exp[F_2], Exp[I(4)])
[1]: Rompf, Odersky: Lightweight Modular Staging: A Pragmatic Approach to Runtime Code Generation and Compiled DSLs. GPCE’10

4. DSL in Scala: SPL
( DFT(k) tensor I(m) ) compose T(n, m) compose ( I(k) tensor DFT(m) ) compose L(n, k)
Binding times distinguished only by types
Full host language available to process the DSL
Sharing of DSL infrastructure possible between DSLs

5. Rewriting
Pattern matching in Scala naturally supports this

6. Compilation DSL to DSL
Subset of C as DSL

7. State of the Work Level 1 Straight-line Code PCDI/ICCS 2001 Level 2
Looped Code
Sigma SPL
PLDI 2005
Level 3
Parallelism
Tag based rewriting
SC 2006
Level 4
Library Generation
Recursion step closure
CGO 2009
Markus Püschel, Franz Franchetti and Yevgen Voronenko, Spiral, in Encyclopedia of Parallel Computing, Eds. David Padua, Springer 2011