Futhark.Pass.ExtractKernels.Interchange

It is well known that fully parallel loops can always be interchanged inwards with a sequential loop. This module implements that transformation.

This is also where we implement loop-switching (for branches), which is semantically similar to interchange.

Documentation

data SeqLoop

An encoding of a sequential do-loop with no existential context, alongside its result pattern.

Constructors

SeqLoop [Int] (Pat Type) [(FParam SOACS, SubExp)] LoopForm (Body SOACS)

interchangeLoops :: (MonadFreshNames m, HasScope SOACS m) => KernelNest -> SeqLoop -> m (Stms SOACS)

Given a (parallel) map nesting and an inner sequential loop, move the maps inside the sequential loop. The result is several statements - one of these will be the loop, which will then contain statements with map expressions.

data Branch

An encoding of a branch with alongside its result pattern.

Constructors

Branch [Int] (Pat Type) [SubExp] [Case (Body SOACS)] (Body SOACS) (MatchDec (BranchType SOACS))

interchangeBranch :: (MonadFreshNames m, HasScope SOACS m) => KernelNest -> Branch -> m (Stm SOACS)

Given a (parallel) map nesting and an inner branch, move the maps inside the branch. The result is the resulting branch expression, which will then contain statements with map expressions.

data WithAccStm

An encoding of a WithAcc with alongside its result pattern.

Constructors

WithAccStm [Int] (Pat Type) [(Shape, [VName], Maybe (Lambda SOACS, [SubExp]))] (Lambda SOACS)

interchangeWithAcc :: (MonadFreshNames m, LocalScope SOACS m) => KernelNest -> WithAccStm -> m (Stm SOACS)

Given a (parallel) map nesting and an inner withacc, move the maps inside the branch. The result is the resulting withacc expression, which will then contain statements with map expressions.