GHC.Types.Id.Info

The IdDetails type

data IdDetails

Identifier Details

The IdDetails of an Id give stable, and necessary, information about the Id.

Constructors

VanillaId

RecSelId

The Id for a record selector

Fields

• sel_tycon :: RecSelParent
• sel_naughty :: Bool

DataConWorkId DataCon

The Id is for a data constructor worker

DataConWrapId DataCon

The Id is for a data constructor wrapper

ClassOpId Class

The Id is a superclass selector, or class operation of a class

PrimOpId PrimOp

The Id is for a primitive operator

FCallId ForeignCall

The Id is for a foreign call. Type will be simple: no type families, newtypes, etc

TickBoxOpId TickBoxOp

The Id is for a HPC tick box (both traditional and binary)

DFunId Bool

A dictionary function. Bool = True = the class has only one method, so may be implemented with a newtype, so it might be bad to be strict on this dictionary

CoVarId

A coercion variable This only covers un-lifted coercions, of type (t1 ~ t2), not their lifted variants

JoinId JoinArity (Maybe [CbvMark])

An Id for a join point taking n arguments Note [Join points] in GHC.Core Can also work as a StrictWorkerId if given CbvMarks. See Note [Strict Worker Ids]

StrictWorkerId [CbvMark]

An Id for a worker function, which expects some arguments to be passed both evaluated and tagged. See Note [Strict Worker Ids] See Note [Tag Inference]

Instances

Outputable IdDetails

Defined in GHC.Types.Id.Info

Methods

ppr :: IdDetails -> SDoc

pprIdDetails :: IdDetails -> SDoc

coVarDetails :: IdDetails

Just a synonym for CoVarId. Written separately so it can be exported in the hs-boot file.

isCoVarDetails :: IdDetails -> Bool

Check if an IdDetails says CoVarId.

type JoinArity = Int

The number of arguments that a join point takes. Unlike the arity of a function, this is a purely syntactic property and is fixed when the join point is created (or converted from a value). Both type and value arguments are counted.

isJoinIdDetails_maybe :: IdDetails -> Maybe (JoinArity, Maybe [CbvMark])

data RecSelParent

Recursive Selector Parent

Constructors

RecSelData TyCon

RecSelPatSyn PatSyn

Instances

Eq RecSelParent

Defined in GHC.Types.Id.Info

Methods

(==) :: RecSelParent -> RecSelParent -> Bool

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

Outputable RecSelParent

Defined in GHC.Types.Id.Info

Methods

ppr :: RecSelParent -> SDoc

The IdInfo type

data IdInfo

Identifier Information

An IdInfo gives optional information about an Id. If present it never lies, but it may not be present, in which case there is always a conservative assumption which can be made.

Two Ids may have different info even though they have the same Unique (and are hence the same Id); for example, one might lack the properties attached to the other.

Most of the IdInfo gives information about the value, or definition, of the Id, independent of its usage. Exceptions to this are demandInfo, occInfo, oneShotInfo and callArityInfo.

Performance note: when we update IdInfo, we have to reallocate this entire record, so it is a good idea not to let this data structure get too big.

Instances

Outputable IdInfo

Defined in GHC.Core.Ppr

Methods

ppr :: IdInfo -> SDoc

vanillaIdInfo :: IdInfo

Basic IdInfo that carries no useful information whatsoever

noCafIdInfo :: IdInfo

More informative IdInfo we can use when we know the Id has no CAF references

The OneShotInfo type

data OneShotInfo

If the Id is a lambda-bound variable then it may have lambda-bound variable info. Sometimes we know whether the lambda binding this variable is a "one-shot" lambda; that is, whether it is applied at most once.

This information may be useful in optimisation, as computations may safely be floated inside such a lambda without risk of duplicating work.

See also Note [OneShotInfo overview] above.

Constructors

NoOneShotInfo

No information

OneShotLam

The lambda is applied at most once.

Instances

Eq OneShotInfo

Defined in GHC.Types.Basic

Methods

(==) :: OneShotInfo -> OneShotInfo -> Bool

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

Outputable OneShotInfo

Defined in GHC.Types.Basic

Methods

ppr :: OneShotInfo -> SDoc

oneShotInfo :: IdInfo -> OneShotInfo

Info about a lambda-bound variable, if the Id is one

noOneShotInfo :: OneShotInfo

It is always safe to assume that an Id has no lambda-bound variable information

hasNoOneShotInfo :: OneShotInfo -> Bool

setOneShotInfo :: IdInfo -> OneShotInfo -> IdInfo infixl 1

Zapping various forms of Info

zapLamInfo :: IdInfo -> Maybe IdInfo

This is used to remove information on lambda binders that we have setup as part of a lambda group, assuming they will be applied all at once, but turn out to be part of an unsaturated lambda as in e.g:

(\x1. \x2. e) arg1

zapFragileInfo :: IdInfo -> Maybe IdInfo

Zap info that depends on free variables

zapDemandInfo :: IdInfo -> Maybe IdInfo

Remove all demand info on the IdInfo

zapUsageInfo :: IdInfo -> Maybe IdInfo

Remove usage (but not strictness) info on the IdInfo

zapUsageEnvInfo :: IdInfo -> Maybe IdInfo

Remove usage environment info from the strictness signature on the IdInfo

zapUsedOnceInfo :: IdInfo -> Maybe IdInfo

zapTailCallInfo :: IdInfo -> Maybe IdInfo

zapCallArityInfo :: IdInfo -> IdInfo

zapUnfolding :: Unfolding -> Unfolding

The ArityInfo type

type ArityInfo = Arity

Arity Information

An ArityInfo of n tells us that partial application of this Id to up to n-1 value arguments does essentially no work.

That is not necessarily the same as saying that it has n leading lambdas, because coerces may get in the way.

The arity might increase later in the compilation process, if an extra lambda floats up to the binding site.

Invariant: the Arity of an Id must never exceed the number of value arguments that appear in the type of the Id. See Note [Arity and function types].

unknownArity :: Arity

It is always safe to assume that an Id has an arity of 0

arityInfo :: IdInfo -> ArityInfo

Id arity, as computed by GHC.Core.Opt.Arity. Specifies how many arguments this Id has to be applied to before it doesn any meaningful work.

setArityInfo :: IdInfo -> ArityInfo -> IdInfo infixl 1

ppArityInfo :: Int -> SDoc

callArityInfo :: IdInfo -> ArityInfo

How this is called. This is the number of arguments to which a binding can be eta-expanded without losing any sharing. n = all calls have at least n arguments

setCallArityInfo :: IdInfo -> ArityInfo -> IdInfo

Demand and strictness Info

dmdSigInfo :: IdInfo -> DmdSig

A strictness signature. Digests how a function uses its arguments if applied to at least arityInfo arguments.

setDmdSigInfo :: IdInfo -> DmdSig -> IdInfo infixl 1

cprSigInfo :: IdInfo -> CprSig

Information on whether the function will ultimately return a freshly allocated constructor.

setCprSigInfo :: IdInfo -> CprSig -> IdInfo infixl 1

demandInfo :: IdInfo -> Demand

ID demand information

setDemandInfo :: IdInfo -> Demand -> IdInfo infixl 1

pprStrictness :: DmdSig -> SDoc

Unfolding Info

realUnfoldingInfo :: IdInfo -> Unfolding

The Ids unfolding

unfoldingInfo :: IdInfo -> Unfolding

Essentially returns the realUnfoldingInfo field, but does not expose the unfolding of a strong loop breaker.

This is the right thing to call if you plan to decide whether an unfolding will inline.

setUnfoldingInfo :: IdInfo -> Unfolding -> IdInfo infixl 1

hasInlineUnfolding :: IdInfo -> Bool

True of a non-loop-breaker Id that has a stable unfolding that is (a) always inlined; that is, with an UnfWhen guidance, or (b) a DFunUnfolding which never needs to be inlined

The InlinePragInfo type

type InlinePragInfo = InlinePragma

Inline Pragma Information

Tells when the inlining is active. When it is active the thing may be inlined, depending on how big it is.

If there was an INLINE pragma, then as a separate matter, the RHS will have been made to look small with a Core inline Note

The default InlinePragInfo is AlwaysActive, so the info serves entirely as a way to inhibit inlining until we want it

inlinePragInfo :: IdInfo -> InlinePragma

Any inline pragma attached to the Id

setInlinePragInfo :: IdInfo -> InlinePragma -> IdInfo infixl 1

The OccInfo type

data OccInfo

identifier Occurrence Information

Constructors

ManyOccs

There are many occurrences, or unknown occurrences

Fields

• occ_tail :: !TailCallInfo

IAmDead

Marks unused variables. Sometimes useful for lambda and case-bound variables.

OneOcc

Occurs exactly once (per branch), not inside a rule

Fields

• occ_in_lam :: !InsideLam
• occ_n_br :: !BranchCount
• occ_int_cxt :: !InterestingCxt
• occ_tail :: !TailCallInfo

IAmALoopBreaker

This identifier breaks a loop of mutually recursive functions. The field marks whether it is only a loop breaker due to a reference in a rule

Fields

• occ_rules_only :: !RulesOnly
• occ_tail :: !TailCallInfo

Instances

Eq OccInfo

Defined in GHC.Types.Basic

Methods

(==) :: OccInfo -> OccInfo -> Bool

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

Outputable OccInfo

Defined in GHC.Types.Basic

Methods

ppr :: OccInfo -> SDoc

isDeadOcc :: OccInfo -> Bool

isStrongLoopBreaker :: OccInfo -> Bool

isWeakLoopBreaker :: OccInfo -> Bool

occInfo :: IdInfo -> OccInfo

How the Id occurs in the program

setOccInfo :: IdInfo -> OccInfo -> IdInfo infixl 1

data InsideLam

Inside Lambda

Constructors

IsInsideLam

Occurs inside a non-linear lambda Substituting a redex for this occurrence is dangerous because it might duplicate work.

NotInsideLam

Instances

Eq InsideLam

Defined in GHC.Types.Basic

Methods

(==) :: InsideLam -> InsideLam -> Bool

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

Semigroup InsideLam

If any occurrence of an identifier is inside a lambda, then the occurrence info of that identifier marks it as occurring inside a lambda

Defined in GHC.Types.Basic

Methods

(<>) :: InsideLam -> InsideLam -> InsideLam

sconcat :: NonEmpty InsideLam -> InsideLam

stimes :: Integral b => b -> InsideLam -> InsideLam

Monoid InsideLam

Defined in GHC.Types.Basic

Methods

mempty :: InsideLam

mappend :: InsideLam -> InsideLam -> InsideLam

mconcat :: [InsideLam] -> InsideLam

type BranchCount = Int

data TailCallInfo

Constructors

AlwaysTailCalled JoinArity

NoTailCallInfo

Instances

Eq TailCallInfo

Defined in GHC.Types.Basic

Methods

(==) :: TailCallInfo -> TailCallInfo -> Bool

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

Outputable TailCallInfo

Defined in GHC.Types.Basic

Methods

ppr :: TailCallInfo -> SDoc

tailCallInfo :: OccInfo -> TailCallInfo

isAlwaysTailCalled :: OccInfo -> Bool

The RuleInfo type

data RuleInfo

Rule Information

Records the specializations of this Id that we know about in the form of rewrite CoreRules that target them

Constructors

RuleInfo [CoreRule] DVarSet

emptyRuleInfo :: RuleInfo

Assume that no specializations exist: always safe

isEmptyRuleInfo :: RuleInfo -> Bool

ruleInfoFreeVars :: RuleInfo -> DVarSet

Retrieve the locally-defined free variables of both the left and right hand sides of the specialization rules

ruleInfoRules :: RuleInfo -> [CoreRule]

setRuleInfoHead :: Name -> RuleInfo -> RuleInfo

Change the name of the function the rule is keyed on all of the CoreRules

ruleInfo :: IdInfo -> RuleInfo

Specialisations of the Ids function which exist. See Note [Specialisations and RULES in IdInfo]

setRuleInfo :: IdInfo -> RuleInfo -> IdInfo infixl 1

tagSigInfo :: IdInfo -> Maybe TagSig

The CAFInfo type

data CafInfo

Constant applicative form Information

Records whether an Id makes Constant Applicative Form references

Constructors

MayHaveCafRefs

Indicates that the Id is for either:

1. A function or static constructor that refers to one or more CAFs, or
2. A real live CAF

NoCafRefs

A function or static constructor that refers to no CAFs.

Instances

Eq CafInfo

Defined in GHC.Types.Id.Info

Methods

(==) :: CafInfo -> CafInfo -> Bool

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

Ord CafInfo

Defined in GHC.Types.Id.Info

Methods

compare :: CafInfo -> CafInfo -> Ordering

(<) :: CafInfo -> CafInfo -> Bool

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

(>) :: CafInfo -> CafInfo -> Bool

(>=) :: CafInfo -> CafInfo -> Bool

max :: CafInfo -> CafInfo -> CafInfo

min :: CafInfo -> CafInfo -> CafInfo

Outputable CafInfo

Defined in GHC.Types.Id.Info

Methods

ppr :: CafInfo -> SDoc

ppCafInfo :: CafInfo -> SDoc

mayHaveCafRefs :: CafInfo -> Bool

cafInfo :: IdInfo -> CafInfo

Id CAF info

setCafInfo :: IdInfo -> CafInfo -> IdInfo infixl 1

The LambdaFormInfo type

data LambdaFormInfo

Information about an identifier, from the code generator's point of view. Every identifier is bound to a LambdaFormInfo in the environment, which gives the code generator enough info to be able to tail call or return that identifier.

Instances

Outputable LambdaFormInfo

Defined in GHC.StgToCmm.Types

Methods

ppr :: LambdaFormInfo -> SDoc

lfInfo :: IdInfo -> Maybe LambdaFormInfo

setLFInfo :: IdInfo -> LambdaFormInfo -> IdInfo

setTagSig :: IdInfo -> TagSig -> IdInfo

tagSig :: IdInfo -> Maybe TagSig

Tick-box Info

data TickBoxOp

Tick box for Hpc-style coverage

Constructors

TickBox Module !TickBoxId

Instances

Outputable TickBoxOp

Defined in GHC.Types.Id.Info

Methods

ppr :: TickBoxOp -> SDoc

type TickBoxId = Int