Futhark.Optimise.CSE

This module implements common-subexpression elimination. This module does not actually remove the duplicate, but only replaces one with a diference to the other. E.g:

  let a = x + y
  let b = x + y

becomes:

  let a = x + y
  let b = a

After which copy propagation in the simplifier will actually remove the definition of b.

Our CSE is still rather stupid. No normalisation is performed, so the expressions x+y and y+x will be considered distinct. Furthermore, no expression with its own binding will be considered equal to any other, since the variable names will be distinct. This affects SOACs in particular.

Documentation

performCSE :: (ASTLore lore, CanBeAliased (Op lore), CSEInOp (OpWithAliases (Op lore))) => Bool -> Pass lore lore

Perform CSE on every function in a program.

If the boolean argument is false, the pass will not perform CSE on expressions producing arrays. This should be disabled when the lore has memory information, since at that point arrays have identity beyond their value.

performCSEOnFunDef :: (ASTLore lore, CanBeAliased (Op lore), CSEInOp (OpWithAliases (Op lore))) => Bool -> FunDef lore -> FunDef lore

Perform CSE on a single function.

If the boolean argument is false, the pass will not perform CSE on expressions producing arrays. This should be disabled when the lore has memory information, since at that point arrays have identity beyond their value.

performCSEOnStms :: (ASTLore lore, CanBeAliased (Op lore), CSEInOp (OpWithAliases (Op lore))) => Bool -> Stms lore -> Stms lore

Perform CSE on some statements.

If the boolean argument is false, the pass will not perform CSE on expressions producing arrays. This should be disabled when the lore has memory information, since at that point arrays have identity beyond their value.

class CSEInOp op

The operations that permit CSE.

Minimal complete definition

cseInOp

Instances

CSEInOp ()

Defined in Futhark.Optimise.CSE

Methods

cseInOp :: () -> CSEM lore ()

(ASTLore lore, CanBeAliased (Op lore), CSEInOp (OpWithAliases (Op lore))) => CSEInOp (SOAC (Aliases lore))

Defined in Futhark.Optimise.CSE

Methods

cseInOp :: SOAC (Aliases lore) -> CSEM lore0 (SOAC (Aliases lore))

CSEInOp op => CSEInOp (MemOp op)

Defined in Futhark.Optimise.CSE

Methods

cseInOp :: MemOp op -> CSEM lore (MemOp op)

(ASTLore lore, Aliased lore, CSEInOp (Op lore)) => CSEInOp (SegOp lvl lore)

Defined in Futhark.Optimise.CSE

Methods

cseInOp :: SegOp lvl lore -> CSEM lore0 (SegOp lvl lore)

(ASTLore lore, Aliased lore, CSEInOp (Op lore), CSEInOp op) => CSEInOp (MCOp lore op)

Defined in Futhark.Optimise.CSE

Methods

cseInOp :: MCOp lore op -> CSEM lore0 (MCOp lore op)

(ASTLore lore, Aliased lore, CSEInOp (Op lore), CSEInOp op) => CSEInOp (HostOp lore op)

Defined in Futhark.Optimise.CSE

Methods

cseInOp :: HostOp lore op -> CSEM lore0 (HostOp lore op)