Futhark.IR.Mem

Building blocks for defining representations where every array is given information about which memory block is it based in, and how array elements map to memory block offsets.

There are two primary concepts you will need to understand:

1. Memory blocks, which are Futhark values of type Mem (parametrized with their size). These correspond to arbitrary blocks of memory, and are created using the Alloc operation.
2. Index functions, which describe a mapping from the index space of an array (eg. a two-dimensional space for an array of type [[int]]) to a one-dimensional offset into a memory block. Thus, index functions describe how arbitrary-dimensional arrays are mapped to the single-dimensional world of memory.

At a conceptual level, imagine that we have a two-dimensional array a of 32-bit integers, consisting of n rows of m elements each. This array could be represented in classic row-major format with an index function like the following:

  f(i,j) = i * m + j

When we want to know the location of element a[2,3], we simply call the index function as f(2,3) and obtain 2*m+3. We could also have chosen another index function, one that represents the array in column-major (or "transposed") format:

  f(i,j) = j * n + i

Index functions are not Futhark-level functions, but a special construct that the final code generator will eventually use to generate concrete access code. By modifying the index functions we can change how an array is represented in memory, which can permit memory access pattern optimisations.

Every time we bind an array, whether in a let-binding, loop merge parameter, or lambda parameter, we have an annotation specifying a memory block and an index function. In some cases, such as let-bindings for many expressions, we are free to specify an arbitrary index function and memory block - for example, we get to decide where Copy stores its result - but in other cases the type rules of the expression chooses for us. For example, Index always produces an array in the same memory block as its input, and with the same index function, except with some indices fixed.

Documentation

type LetDecMem = MemInfo SubExp NoUniqueness MemBind

type FParamMem = MemInfo SubExp Uniqueness MemBind

type LParamMem = MemInfo SubExp NoUniqueness MemBind

type RetTypeMem = FunReturns

type BranchTypeMem = BodyReturns

data MemOp inner

Constructors

Alloc SubExp Space

Allocate a memory block. This really should not be an expression, but what are you gonna do...

Inner inner

Instances

Eq inner => Eq (MemOp inner)

Defined in Futhark.IR.Mem

Methods

(==) :: MemOp inner -> MemOp inner -> Bool

(/=) :: MemOp inner -> MemOp inner -> Bool

Ord inner => Ord (MemOp inner)

Defined in Futhark.IR.Mem

Methods

compare :: MemOp inner -> MemOp inner -> Ordering

(<) :: MemOp inner -> MemOp inner -> Bool

(<=) :: MemOp inner -> MemOp inner -> Bool

(>) :: MemOp inner -> MemOp inner -> Bool

(>=) :: MemOp inner -> MemOp inner -> Bool

max :: MemOp inner -> MemOp inner -> MemOp inner

min :: MemOp inner -> MemOp inner -> MemOp inner

Show inner => Show (MemOp inner)

Defined in Futhark.IR.Mem

Methods

showsPrec :: Int -> MemOp inner -> ShowS

show :: MemOp inner -> String

showList :: [MemOp inner] -> ShowS

Pretty inner => Pretty (MemOp inner)

Defined in Futhark.IR.Mem

Methods

ppr :: MemOp inner -> Doc

pprPrec :: Int -> MemOp inner -> Doc

pprList :: [MemOp inner] -> Doc

TypedOp inner => TypedOp (MemOp inner)

Defined in Futhark.IR.Mem

Methods

opType :: HasScope t m => MemOp inner -> m [ExtType]

FreeIn inner => FreeIn (MemOp inner)

Defined in Futhark.IR.Mem

Methods

freeIn' :: MemOp inner -> FV

Substitute inner => Substitute (MemOp inner)

Defined in Futhark.IR.Mem

Methods

substituteNames :: Map VName VName -> MemOp inner -> MemOp inner

Rename inner => Rename (MemOp inner)

Defined in Futhark.IR.Mem

Methods

rename :: MemOp inner -> RenameM (MemOp inner)

IsOp inner => IsOp (MemOp inner)

Defined in Futhark.IR.Mem

Methods

safeOp :: MemOp inner -> Bool

cheapOp :: MemOp inner -> Bool

CanBeAliased inner => CanBeAliased (MemOp inner)

Defined in Futhark.IR.Mem

Associated Types

type OpWithAliases (MemOp inner)

Methods

removeOpAliases :: OpWithAliases (MemOp inner) -> MemOp inner

addOpAliases :: AliasTable -> MemOp inner -> OpWithAliases (MemOp inner)

AliasedOp inner => AliasedOp (MemOp inner)

Defined in Futhark.IR.Mem

Methods

opAliases :: MemOp inner -> [Names]

consumedInOp :: MemOp inner -> Names

OpMetrics inner => OpMetrics (MemOp inner)

Defined in Futhark.IR.Mem

Methods

opMetrics :: MemOp inner -> MetricsM ()

CanBeWise inner => CanBeWise (MemOp inner)

Defined in Futhark.IR.Mem

Associated Types

type OpWithWisdom (MemOp inner)

Methods

removeOpWisdom :: OpWithWisdom (MemOp inner) -> MemOp inner

IndexOp inner => IndexOp (MemOp inner)

Defined in Futhark.IR.Mem

Methods

indexOp :: (ASTRep rep, IndexOp (Op rep)) => SymbolTable rep -> Int -> MemOp inner -> [TPrimExp Int64 VName] -> Maybe Indexed

AllocOp (MemOp inner)

Defined in Futhark.IR.Mem

Methods

allocOp :: SubExp -> Space -> MemOp inner

SizeSubst op => SizeSubst (MemOp op)

Defined in Futhark.Pass.ExplicitAllocations

Methods

opSizeSubst :: PatternT dec -> MemOp op -> ChunkMap

opIsConst :: MemOp op -> Bool

CSEInOp op => CSEInOp (MemOp op)

Defined in Futhark.Optimise.CSE

Methods

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

type OpWithAliases (MemOp inner)

Defined in Futhark.IR.Mem

type OpWithAliases (MemOp inner) = MemOp (OpWithAliases inner)

type OpWithWisdom (MemOp inner)

Defined in Futhark.IR.Mem

type OpWithWisdom (MemOp inner) = MemOp (OpWithWisdom inner)

data MemInfo d u ret

A summary of the memory information for every let-bound identifier, function parameter, and return value. Parameterisered over uniqueness, dimension, and auxiliary array information.

Constructors

MemPrim PrimType

A primitive value.

MemMem Space

A memory block.

MemArray PrimType (ShapeBase d) u ret

The array is stored in the named memory block, and with the given index function. The index function maps indices in the array to element offset, not byte offsets! To translate to byte offsets, multiply the offset with the size of the array element type.

MemAcc VName Shape [Type] u

An accumulator, which is not stored anywhere.

Instances

IsRetType FunReturns

Defined in Futhark.IR.Mem

Methods

primRetType :: PrimType -> FunReturns

applyRetType :: Typed dec => [FunReturns] -> [Param dec] -> [(SubExp, Type)] -> Maybe [FunReturns]

IsBodyType BodyReturns

Defined in Futhark.IR.Mem

Methods

primBodyType :: PrimType -> BodyReturns

Simplifiable [FunReturns]

Defined in Futhark.IR.Mem

Methods

simplify :: SimplifiableRep rep => [FunReturns] -> SimpleM rep [FunReturns]

(Eq d, Eq u, Eq ret) => Eq (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

(==) :: MemInfo d u ret -> MemInfo d u ret -> Bool

(/=) :: MemInfo d u ret -> MemInfo d u ret -> Bool

(Ord d, Ord u, Ord ret) => Ord (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

compare :: MemInfo d u ret -> MemInfo d u ret -> Ordering

(<) :: MemInfo d u ret -> MemInfo d u ret -> Bool

(<=) :: MemInfo d u ret -> MemInfo d u ret -> Bool

(>) :: MemInfo d u ret -> MemInfo d u ret -> Bool

(>=) :: MemInfo d u ret -> MemInfo d u ret -> Bool

max :: MemInfo d u ret -> MemInfo d u ret -> MemInfo d u ret

min :: MemInfo d u ret -> MemInfo d u ret -> MemInfo d u ret

(Show d, Show u, Show ret) => Show (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

showsPrec :: Int -> MemInfo d u ret -> ShowS

show :: MemInfo d u ret -> String

showList :: [MemInfo d u ret] -> ShowS

(Pretty (ShapeBase d), Pretty (TypeBase (ShapeBase d) u), Pretty d, Pretty u, Pretty ret) => Pretty (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

ppr :: MemInfo d u ret -> Doc

pprPrec :: Int -> MemInfo d u ret -> Doc

pprList :: [MemInfo d u ret] -> Doc

FixExt ret => FixExt (MemInfo ExtSize u ret)

Defined in Futhark.IR.Mem

Methods

fixExt :: Int -> SubExp -> MemInfo ExtSize u ret -> MemInfo ExtSize u ret

FixExt ret => DeclExtTyped (MemInfo ExtSize Uniqueness ret)

Defined in Futhark.IR.Mem

Methods

declExtTypeOf :: MemInfo ExtSize Uniqueness ret -> DeclExtType

FixExt ret => ExtTyped (MemInfo ExtSize NoUniqueness ret)

Defined in Futhark.IR.Mem

Methods

extTypeOf :: MemInfo ExtSize NoUniqueness ret -> ExtType

DeclTyped (MemInfo SubExp Uniqueness ret)

Defined in Futhark.IR.Mem

Methods

declTypeOf :: MemInfo SubExp Uniqueness ret -> DeclType

Typed (MemInfo SubExp Uniqueness ret)

Defined in Futhark.IR.Mem

Methods

typeOf :: MemInfo SubExp Uniqueness ret -> Type

Typed (MemInfo SubExp NoUniqueness ret)

Defined in Futhark.IR.Mem

Methods

typeOf :: MemInfo SubExp NoUniqueness ret -> Type

(FreeIn d, FreeIn ret) => FreeIn (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

freeIn' :: MemInfo d u ret -> FV

(Substitute d, Substitute ret) => Substitute (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

substituteNames :: Map VName VName -> MemInfo d u ret -> MemInfo d u ret

(Substitute d, Substitute ret) => Rename (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

rename :: MemInfo d u ret -> RenameM (MemInfo d u ret)

(Simplifiable d, Simplifiable ret) => Simplifiable (MemInfo d u ret)

Defined in Futhark.IR.Mem

Methods

simplify :: SimplifiableRep rep => MemInfo d u ret -> SimpleM rep (MemInfo d u ret)

type MemBound u = MemInfo SubExp u MemBind

data MemBind

Memory information for an array bound somewhere in the program.

Constructors

ArrayIn VName IxFun

Located in this memory block with this index function.

Instances

Eq MemBind

Defined in Futhark.IR.Mem

Methods

(==) :: MemBind -> MemBind -> Bool

(/=) :: MemBind -> MemBind -> Bool

Ord MemBind

Defined in Futhark.IR.Mem

Methods

compare :: MemBind -> MemBind -> Ordering

(<) :: MemBind -> MemBind -> Bool

(<=) :: MemBind -> MemBind -> Bool

(>) :: MemBind -> MemBind -> Bool

(>=) :: MemBind -> MemBind -> Bool

max :: MemBind -> MemBind -> MemBind

min :: MemBind -> MemBind -> MemBind

Show MemBind

Defined in Futhark.IR.Mem

Methods

showsPrec :: Int -> MemBind -> ShowS

show :: MemBind -> String

showList :: [MemBind] -> ShowS

Pretty MemBind

Defined in Futhark.IR.Mem

Methods

ppr :: MemBind -> Doc

pprPrec :: Int -> MemBind -> Doc

pprList :: [MemBind] -> Doc

FreeIn MemBind

Defined in Futhark.IR.Mem

Methods

freeIn' :: MemBind -> FV

Substitute MemBind

Defined in Futhark.IR.Mem

Methods

substituteNames :: Map VName VName -> MemBind -> MemBind

Rename MemBind

Defined in Futhark.IR.Mem

Methods

rename :: MemBind -> RenameM MemBind

Simplifiable MemBind

Defined in Futhark.IR.Mem

Methods

simplify :: SimplifiableRep rep => MemBind -> SimpleM rep MemBind

data MemReturn

A description of the memory properties of an array being returned by an operation.

Constructors

ReturnsInBlock VName ExtIxFun

The array is located in a memory block that is already in scope.

ReturnsNewBlock Space Int ExtIxFun

The operation returns a new (existential) memory block.

Instances

Eq MemReturn

Defined in Futhark.IR.Mem

Methods

(==) :: MemReturn -> MemReturn -> Bool

(/=) :: MemReturn -> MemReturn -> Bool

Ord MemReturn

Defined in Futhark.IR.Mem

Methods

compare :: MemReturn -> MemReturn -> Ordering

(<) :: MemReturn -> MemReturn -> Bool

(<=) :: MemReturn -> MemReturn -> Bool

(>) :: MemReturn -> MemReturn -> Bool

(>=) :: MemReturn -> MemReturn -> Bool

max :: MemReturn -> MemReturn -> MemReturn

min :: MemReturn -> MemReturn -> MemReturn

Show MemReturn

Defined in Futhark.IR.Mem

Methods

showsPrec :: Int -> MemReturn -> ShowS

show :: MemReturn -> String

showList :: [MemReturn] -> ShowS

Pretty MemReturn

Defined in Futhark.IR.Mem

Methods

ppr :: MemReturn -> Doc

pprPrec :: Int -> MemReturn -> Doc

pprList :: [MemReturn] -> Doc

FixExt MemReturn

Defined in Futhark.IR.Mem

Methods

fixExt :: Int -> SubExp -> MemReturn -> MemReturn

IsRetType FunReturns

Defined in Futhark.IR.Mem

Methods

primRetType :: PrimType -> FunReturns

applyRetType :: Typed dec => [FunReturns] -> [Param dec] -> [(SubExp, Type)] -> Maybe [FunReturns]

IsBodyType BodyReturns

Defined in Futhark.IR.Mem

Methods

primBodyType :: PrimType -> BodyReturns

FreeIn MemReturn

Defined in Futhark.IR.Mem

Methods

freeIn' :: MemReturn -> FV

Substitute MemReturn

Defined in Futhark.IR.Mem

Methods

substituteNames :: Map VName VName -> MemReturn -> MemReturn

Rename MemReturn

Defined in Futhark.IR.Mem

Methods

rename :: MemReturn -> RenameM MemReturn

Simplifiable MemReturn

Defined in Futhark.IR.Mem

Methods

simplify :: SimplifiableRep rep => MemReturn -> SimpleM rep MemReturn

Simplifiable [FunReturns]

Defined in Futhark.IR.Mem

Methods

simplify :: SimplifiableRep rep => [FunReturns] -> SimpleM rep [FunReturns]

type IxFun = IxFun (TPrimExp Int64 VName)

The index function representation used for memory annotations.

type ExtIxFun = IxFun (TPrimExp Int64 (Ext VName))

An index function that may contain existential variables.

isStaticIxFun :: ExtIxFun -> Maybe IxFun

type ExpReturns = MemInfo ExtSize NoUniqueness (Maybe MemReturn)

The memory return of an expression. An array is annotated with Maybe MemReturn, which can be interpreted as the expression either dictating exactly where the array is located when it is returned (if Just), or able to put it whereever the binding prefers (if Nothing).

This is necessary to capture the difference between an expression that is just an array-typed variable, in which the array being "returned" is located where it already is, and a copy expression, whose entire purpose is to store an existing array in some arbitrary location. This is a consequence of the design decision never to have implicit memory copies.

type BodyReturns = MemInfo ExtSize NoUniqueness MemReturn

The return of a body, which must always indicate where returned arrays are located.

type FunReturns = MemInfo ExtSize Uniqueness MemReturn

The memory return of a function, which must always indicate where returned arrays are located.

noUniquenessReturns :: MemInfo d u r -> MemInfo d NoUniqueness r

bodyReturnsToExpReturns :: BodyReturns -> ExpReturns

type Mem rep = (AllocOp (Op rep), FParamInfo rep ~ FParamMem, LParamInfo rep ~ LParamMem, LetDec rep ~ LetDecMem, RetType rep ~ RetTypeMem, BranchType rep ~ BranchTypeMem, ASTRep rep, OpReturns rep)

class AllocOp op where

The class of ops that have memory allocation.

Methods

allocOp :: SubExp -> Space -> op

Instances

AllocOp (MemOp inner)

Defined in Futhark.IR.Mem

Methods

allocOp :: SubExp -> Space -> MemOp inner

class TypedOp (Op rep) => OpReturns rep where

Minimal complete definition

Nothing

Methods

opReturns :: (Monad m, HasScope rep m) => Op rep -> m [ExpReturns]

Instances

OpReturns SeqMem

Defined in Futhark.IR.SeqMem

Methods

opReturns :: (Monad m, HasScope SeqMem m) => Op SeqMem -> m [ExpReturns]

OpReturns MCMem

Defined in Futhark.IR.MCMem

Methods

opReturns :: (Monad m, HasScope MCMem m) => Op MCMem -> m [ExpReturns]

OpReturns GPUMem

Defined in Futhark.IR.GPUMem

Methods

opReturns :: (Monad m, HasScope GPUMem m) => Op GPUMem -> m [ExpReturns]

varReturns :: (HasScope rep m, Monad m, Mem rep) => VName -> m ExpReturns

expReturns :: (Monad m, LocalScope rep m, Mem rep) => Exp rep -> m [ExpReturns]

The return information of an expression. This can be seen as the "return type with memory annotations" of the expression.

extReturns :: [ExtType] -> [ExpReturns]

lookupMemInfo :: (HasScope rep m, Mem rep) => VName -> m (MemInfo SubExp NoUniqueness MemBind)

subExpMemInfo :: (HasScope rep m, Monad m, Mem rep) => SubExp -> m (MemInfo SubExp NoUniqueness MemBind)

lookupArraySummary :: (Mem rep, HasScope rep m, Monad m) => VName -> m (VName, IxFun (TPrimExp Int64 VName))

existentialiseIxFun :: [VName] -> IxFun -> ExtIxFun

Type checking parts

matchBranchReturnType :: (Mem rep, Checkable rep) => [BodyReturns] -> Body (Aliases rep) -> TypeM rep ()

matchPatternToExp :: (Mem rep, Checkable rep) => Pattern (Aliases rep) -> Exp (Aliases rep) -> TypeM rep ()

matchFunctionReturnType :: (Mem rep, Checkable rep) => [FunReturns] -> Result -> TypeM rep ()

matchLoopResultMem :: (Mem rep, Checkable rep) => [FParam (Aliases rep)] -> [FParam (Aliases rep)] -> [SubExp] -> TypeM rep ()

bodyReturnsFromPattern :: PatternT (MemBound NoUniqueness) -> ([(VName, BodyReturns)], [(VName, BodyReturns)])

checkMemInfo :: Checkable rep => VName -> MemInfo SubExp u MemBind -> TypeM rep ()

Module re-exports

module Futhark.IR.Prop

module Futhark.IR.Traversals

module Futhark.IR.Pretty

module Futhark.IR.Syntax

module Futhark.Analysis.PrimExp.Convert