%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[CoreSyn]{A data type for the Haskell compiler midsection}
\begin{code}
+
+-- | CoreSyn holds all the main data types for use by for the Glasgow Haskell Compiler midsection
module CoreSyn (
+ -- * Main data types
Expr(..), Alt, Bind(..), AltCon(..), Arg, Note(..),
CoreExpr, CoreAlt, CoreBind, CoreArg, CoreBndr,
TaggedExpr, TaggedAlt, TaggedBind, TaggedArg, TaggedBndr(..),
- mkLets, mkLams,
- mkApps, mkTyApps, mkValApps, mkVarApps,
- mkLit, mkIntLitInt, mkIntLit,
- mkConApp,
- varToCoreExpr,
+ -- ** 'Expr' construction
+ mkLets, mkLams,
+ mkApps, mkTyApps, mkVarApps,
+
+ mkIntLit, mkIntLitInt,
+ mkWordLit, mkWordLitWord,
+ mkCharLit, mkStringLit,
+ mkFloatLit, mkFloatLitFloat,
+ mkDoubleLit, mkDoubleLitDouble,
+
+ mkConApp, mkTyBind,
+ varToCoreExpr, varsToCoreExprs,
- isTyVar, isId, cmpAltCon, cmpAlt, ltAlt,
+ isTyVar, isIdVar, cmpAltCon, cmpAlt, ltAlt,
+
+ -- ** Simple 'Expr' access functions and predicates
bindersOf, bindersOfBinds, rhssOfBind, rhssOfAlts,
collectBinders, collectTyBinders, collectValBinders, collectTyAndValBinders,
- collectArgs,
- coreExprCc,
- flattenBinds,
+ collectArgs, coreExprCc, flattenBinds,
isValArg, isTypeArg, valArgCount, valBndrCount, isRuntimeArg, isRuntimeVar,
- -- Unfoldings
+ -- * Unfolding data types
Unfolding(..), UnfoldingGuidance(..), -- Both abstract everywhere but in CoreUnfold.lhs
+
+ -- ** Constructing 'Unfolding's
noUnfolding, evaldUnfolding, mkOtherCon,
- unfoldingTemplate, maybeUnfoldingTemplate, otherCons,
+
+ -- ** Predicates and deconstruction on 'Unfolding'
+ unfoldingTemplate, setUnfoldingTemplate,
+ maybeUnfoldingTemplate, otherCons,
isValueUnfolding, isEvaldUnfolding, isCheapUnfolding, isCompulsoryUnfolding,
- hasUnfolding, hasSomeUnfolding, neverUnfold,
+ isInlineRule, isClosedUnfolding, hasSomeUnfolding, canUnfold, neverUnfoldGuidance,
- -- Seq stuff
+ -- * Strictness
seqExpr, seqExprs, seqUnfolding,
- -- Annotated expressions
- AnnExpr, AnnExpr'(..), AnnBind(..), AnnAlt,
+ -- * Annotated expression data types
+ AnnExpr, AnnExpr'(..), AnnBind(..), AnnAlt,
+
+ -- ** Operations on annotations
deAnnotate, deAnnotate', deAnnAlt, collectAnnBndrs,
- -- Core rules
+ -- * Core rule data types
CoreRule(..), -- CoreSubst, CoreTidy, CoreFVs, PprCore only
- RuleName, seqRules,
- isBuiltinRule, ruleName, isLocalRule, ruleIdName
+ RuleName,
+
+ -- ** Operations on 'CoreRule's
+ seqRules, ruleArity, ruleName, ruleIdName, ruleActivation_maybe,
+ setRuleIdName,
+ isBuiltinRule, isLocalRule
) where
#include "HsVersions.h"
-import StaticFlags ( opt_RuntimeTypes )
-import CostCentre ( CostCentre, noCostCentre )
-import Var ( Var, Id, TyVar, isTyVar, isId )
-import Type ( Type, mkTyVarTy, seqType )
-import Name ( Name )
-import OccName ( OccName )
-import Literal ( Literal, mkMachInt )
-import DataCon ( DataCon, dataConWorkId, dataConTag )
-import BasicTypes ( Activation )
+import CostCentre
+import Var
+import Type
+import Coercion
+import Name
+import Literal
+import DataCon
+import BasicTypes
import FastString
import Outputable
+import Util
+
+import Data.Word
+
+infixl 4 `mkApps`, `mkTyApps`, `mkVarApps`
+-- Left associative, so that we can say (f `mkTyApps` xs `mkVarApps` ys)
\end{code}
%************************************************************************
\begin{code}
infixl 8 `App` -- App brackets to the left
-data Expr b -- "b" for the type of binders,
- = Var Id
- | Lit Literal
- | App (Expr b) (Arg b)
- | Lam b (Expr b)
- | Let (Bind b) (Expr b)
- | Case (Expr b) b Type [Alt b] -- Binder gets bound to value of scrutinee
- -- Invariant: The list of alternatives is ALWAYS EXHAUSTIVE,
- -- meaning that it covers all cases that can occur
- -- See the example below
- --
- -- Invariant: The DEFAULT case must be *first*, if it occurs at all
- -- Invariant: The remaining cases are in order of increasing
- -- tag (for DataAlts)
- -- lit (for LitAlts)
- -- This makes finding the relevant constructor easy,
- -- and makes comparison easier too
- | Note Note (Expr b)
- | Type Type -- This should only show up at the top
- -- level of an Arg
-
--- An "exhausive" case does not necessarily mention all constructors:
--- data Foo = Red | Green | Blue
+-- | This is the data type that represents GHCs core intermediate language. Currently
+-- GHC uses System FC <http://research.microsoft.com/~simonpj/papers/ext-f/> for this purpose,
+-- which is closely related to the simpler and better known System F <http://en.wikipedia.org/wiki/System_F>.
--
--- ...case x of
--- Red -> True
--- other -> f (case x of
--- Green -> ...
--- Blue -> ... )
--- The inner case does not need a Red alternative, because x can't be Red at
--- that program point.
-
-
-type Arg b = Expr b -- Can be a Type
-
-type Alt b = (AltCon, [b], Expr b) -- (DEFAULT, [], rhs) is the default alternative
-
-data AltCon = DataAlt DataCon
- | LitAlt Literal
- | DEFAULT
+-- We get from Haskell source to this Core language in a number of stages:
+--
+-- 1. The source code is parsed into an abstract syntax tree, which is represented
+-- by the data type 'HsExpr.HsExpr' with the names being 'RdrName.RdrNames'
+--
+-- 2. This syntax tree is /renamed/, which attaches a 'Unique.Unique' to every 'RdrName.RdrName'
+-- (yielding a 'Name.Name') to disambiguate identifiers which are lexically identical.
+-- For example, this program:
+--
+-- @
+-- f x = let f x = x + 1
+-- in f (x - 2)
+-- @
+--
+-- Would be renamed by having 'Unique's attached so it looked something like this:
+--
+-- @
+-- f_1 x_2 = let f_3 x_4 = x_4 + 1
+-- in f_3 (x_2 - 2)
+-- @
+--
+-- 3. The resulting syntax tree undergoes type checking (which also deals with instantiating
+-- type class arguments) to yield a 'HsExpr.HsExpr' type that has 'Id.Id' as it's names.
+--
+-- 4. Finally the syntax tree is /desugared/ from the expressive 'HsExpr.HsExpr' type into
+-- this 'Expr' type, which has far fewer constructors and hence is easier to perform
+-- optimization, analysis and code generation on.
+--
+-- The type parameter @b@ is for the type of binders in the expression tree.
+data Expr b
+ = Var Id -- ^ Variables
+ | Lit Literal -- ^ Primitive literals
+ | App (Expr b) (Arg b) -- ^ Applications: note that the argument may be a 'Type'.
+ --
+ -- See "CoreSyn#let_app_invariant" for another invariant
+ | Lam b (Expr b) -- ^ Lambda abstraction
+ | Let (Bind b) (Expr b) -- ^ Recursive and non recursive @let@s. Operationally
+ -- this corresponds to allocating a thunk for the things
+ -- bound and then executing the sub-expression.
+ --
+ -- #top_level_invariant#
+ -- #letrec_invariant#
+ --
+ -- The right hand sides of all top-level and recursive @let@s
+ -- /must/ be of lifted type (see "Type#type_classification" for
+ -- the meaning of /lifted/ vs. /unlifted/).
+ --
+ -- #let_app_invariant#
+ -- The right hand side of of a non-recursive 'Let' _and_ the argument of an 'App',
+ -- /may/ be of unlifted type, but only if the expression
+ -- is ok-for-speculation. This means that the let can be floated around
+ -- without difficulty. For example, this is OK:
+ --
+ -- > y::Int# = x +# 1#
+ --
+ -- But this is not, as it may affect termination if the expression is floated out:
+ --
+ -- > y::Int# = fac 4#
+ --
+ -- In this situation you should use @case@ rather than a @let@. The function
+ -- 'CoreUtils.needsCaseBinding' can help you determine which to generate, or
+ -- alternatively use 'MkCore.mkCoreLet' rather than this constructor directly,
+ -- which will generate a @case@ if necessary
+ --
+ -- #type_let#
+ -- We allow a /non-recursive/ let to bind a type variable, thus:
+ --
+ -- > Let (NonRec tv (Type ty)) body
+ --
+ -- This can be very convenient for postponing type substitutions until
+ -- the next run of the simplifier.
+ --
+ -- At the moment, the rest of the compiler only deals with type-let
+ -- in a Let expression, rather than at top level. We may want to revist
+ -- this choice.
+ | Case (Expr b) b Type [Alt b] -- ^ Case split. Operationally this corresponds to evaluating
+ -- the scrutinee (expression examined) to weak head normal form
+ -- and then examining at most one level of resulting constructor (i.e. you
+ -- cannot do nested pattern matching directly with this).
+ --
+ -- The binder gets bound to the value of the scrutinee,
+ -- and the 'Type' must be that of all the case alternatives
+ --
+ -- #case_invariants#
+ -- This is one of the more complicated elements of the Core language, and comes
+ -- with a number of restrictions:
+ --
+ -- The 'DEFAULT' case alternative must be first in the list, if it occurs at all.
+ --
+ -- The remaining cases are in order of increasing
+ -- tag (for 'DataAlts') or
+ -- lit (for 'LitAlts').
+ -- This makes finding the relevant constructor easy, and makes comparison easier too.
+ --
+ -- The list of alternatives must be exhaustive. An /exhaustive/ case
+ -- does not necessarily mention all constructors:
+ --
+ -- @
+ -- data Foo = Red | Green | Blue
+ -- ... case x of
+ -- Red -> True
+ -- other -> f (case x of
+ -- Green -> ...
+ -- Blue -> ... ) ...
+ -- @
+ --
+ -- The inner case does not need a @Red@ alternative, because @x@ can't be @Red@ at
+ -- that program point.
+ | Cast (Expr b) Coercion -- ^ Cast an expression to a particular type. This is used to implement @newtype@s
+ -- (a @newtype@ constructor or destructor just becomes a 'Cast' in Core) and GADTs.
+ | Note Note (Expr b) -- ^ Notes. These allow general information to be
+ -- added to expressions in the syntax tree
+ | Type Type -- ^ A type: this should only show up at the top
+ -- level of an Arg
+
+-- | Type synonym for expressions that occur in function argument positions.
+-- Only 'Arg' should contain a 'Type' at top level, general 'Expr' should not
+type Arg b = Expr b
+
+-- | A case split alternative. Consists of the constructor leading to the alternative,
+-- the variables bound from the constructor, and the expression to be executed given that binding.
+-- The default alternative is @(DEFAULT, [], rhs)@
+type Alt b = (AltCon, [b], Expr b)
+
+-- | A case alternative constructor (i.e. pattern match)
+data AltCon = DataAlt DataCon -- ^ A plain data constructor: @case e of { Foo x -> ... }@.
+ -- Invariant: the 'DataCon' is always from a @data@ type, and never from a @newtype@
+ | LitAlt Literal -- ^ A literal: @case e of { 1 -> ... }@
+ | DEFAULT -- ^ Trivial alternative: @case e of { _ -> ... }@
deriving (Eq, Ord)
-
+-- | Binding, used for top level bindings in a module and local bindings in a @let@.
data Bind b = NonRec b (Expr b)
- | Rec [(b, (Expr b))]
-
-data Note
- = SCC CostCentre
-
- | Coerce
- Type -- The to-type: type of whole coerce expression
- Type -- The from-type: type of enclosed expression
-
- | InlineMe -- Instructs simplifer to treat the enclosed expression
- -- as very small, and inline it at its call sites
-
- | CoreNote String -- A generic core annotation, propagated but not used by GHC
-
--- NOTE: we also treat expressions wrapped in InlineMe as
--- 'cheap' and 'dupable' (in the sense of exprIsCheap, exprIsDupable)
--- What this means is that we obediently inline even things that don't
--- look like valuse. This is sometimes important:
--- {-# INLINE f #-}
--- f = g . h
--- Here, f looks like a redex, and we aren't going to inline (.) because it's
--- inside an INLINE, so it'll stay looking like a redex. Nevertheless, we
--- should inline f even inside lambdas. In effect, we should trust the programmer.
+ | Rec [(b, (Expr b))]
\end{code}
-INVARIANTS:
+-------------------------- CoreSyn INVARIANTS ---------------------------
-* The RHS of a letrec, and the RHSs of all top-level lets,
- must be of LIFTED type.
+Note [CoreSyn top-level invariant]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+See #toplevel_invariant#
-* The RHS of a let, may be of UNLIFTED type, but only if the expression
- is ok-for-speculation. This means that the let can be floated around
- without difficulty. e.g.
- y::Int# = x +# 1# ok
- y::Int# = fac 4# not ok [use case instead]
+Note [CoreSyn letrec invariant]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+See #letrec_invariant#
-* The argument of an App can be of any type.
+Note [CoreSyn let/app invariant]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+See #let_app_invariant#
+This is intially enforced by DsUtils.mkCoreLet and mkCoreApp
+
+Note [CoreSyn case invariants]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+See #case_invariants#
+
+Note [CoreSyn let goal]
+~~~~~~~~~~~~~~~~~~~~~~~
* The simplifier tries to ensure that if the RHS of a let is a constructor
application, its arguments are trivial, so that the constructor can be
inlined vigorously.
+Note [Type let]
+~~~~~~~~~~~~~~~
+See #type_let#
+
+\begin{code}
+
+-- | Allows attaching extra information to points in expressions rather than e.g. identifiers.
+data Note
+ = SCC CostCentre -- ^ A cost centre annotation for profiling
+ | CoreNote String -- ^ A generic core annotation, propagated but not used by GHC
+\end{code}
+
+
%************************************************************************
%* *
\subsection{Transformation rules}
The CoreRule type and its friends are dealt with mainly in CoreRules,
but CoreFVs, Subst, PprCore, CoreTidy also inspect the representation.
-A Rule is
-
- "local" if the function it is a rule for is defined in the
- same module as the rule itself.
-
- "orphan" if nothing on the LHS is defined in the same module
- as the rule itself
-
\begin{code}
-type RuleName = FastString
-
+-- | A 'CoreRule' is:
+--
+-- * \"Local\" if the function it is a rule for is defined in the
+-- same module as the rule itself.
+--
+-- * \"Orphan\" if nothing on the LHS is defined in the same module
+-- as the rule itself
data CoreRule
= Rule {
- ru_name :: RuleName,
- ru_act :: Activation, -- When the rule is active
+ ru_name :: RuleName, -- ^ Name of the rule, for communication with the user
+ ru_act :: Activation, -- ^ When the rule is active
-- Rough-matching stuff
-- see comments with InstEnv.Instance( is_cls, is_rough )
- ru_fn :: Name, -- Name of the Id at the head of this rule
- ru_rough :: [Maybe Name], -- Name at the head of each argument
+ ru_fn :: Name, -- ^ Name of the 'Id.Id' at the head of this rule
+ ru_rough :: [Maybe Name], -- ^ Name at the head of each argument to the left hand side
-- Proper-matching stuff
-- see comments with InstEnv.Instance( is_tvs, is_tys )
- ru_bndrs :: [CoreBndr], -- Forall'd variables
- ru_args :: [CoreExpr], -- LHS args
+ ru_bndrs :: [CoreBndr], -- ^ Variables quantified over
+ ru_args :: [CoreExpr], -- ^ Left hand side arguments
-- And the right-hand side
- ru_rhs :: CoreExpr,
+ ru_rhs :: CoreExpr, -- ^ Right hand side of the rule
-- Locality
- ru_local :: Bool, -- The fn at the head of the rule is
+ ru_local :: Bool -- ^ @True@ iff the fn at the head of the rule is
-- defined in the same module as the rule
-
- -- Orphan-hood; see comments is InstEnv.Instance( is_orph )
- ru_orph :: Maybe OccName }
-
- | BuiltinRule { -- Built-in rules are used for constant folding
- ru_name :: RuleName, -- and suchlike. It has no free variables.
- ru_fn :: Name, -- Name of the Id at
- -- the head of this rule
- ru_try :: [CoreExpr] -> Maybe CoreExpr }
-
+ -- and is not an implicit 'Id' (like a record selector,
+ -- class operation, or data constructor)
+
+ -- NB: ru_local is *not* used to decide orphan-hood
+ -- c.g. MkIface.coreRuleToIfaceRule
+ }
+
+ -- | Built-in rules are used for constant folding
+ -- and suchlike. They have no free variables.
+ | BuiltinRule {
+ ru_name :: RuleName, -- ^ As above
+ ru_fn :: Name, -- ^ As above
+ ru_nargs :: Int, -- ^ Number of arguments that 'ru_try' expects,
+ -- including type arguments
+ ru_try :: [CoreExpr] -> Maybe CoreExpr
+ -- ^ This function does the rewrite. It given too many
+ -- arguments, it simply discards them; the returned 'CoreExpr'
+ -- is just the rewrite of 'ru_fn' applied to the first 'ru_nargs' args
+ }
+ -- See Note [Extra args in rule matching] in Rules.lhs
+
+isBuiltinRule :: CoreRule -> Bool
isBuiltinRule (BuiltinRule {}) = True
isBuiltinRule _ = False
+-- | The number of arguments the 'ru_fn' must be applied
+-- to before the rule can match on it
+ruleArity :: CoreRule -> Int
+ruleArity (BuiltinRule {ru_nargs = n}) = n
+ruleArity (Rule {ru_args = args}) = length args
+
ruleName :: CoreRule -> RuleName
ruleName = ru_name
+ruleActivation_maybe :: CoreRule -> Maybe Activation
+ruleActivation_maybe (BuiltinRule { }) = Nothing
+ruleActivation_maybe (Rule { ru_act = act }) = Just act
+
+-- | The 'Name' of the 'Id.Id' at the head of the rule left hand side
ruleIdName :: CoreRule -> Name
ruleIdName = ru_fn
isLocalRule :: CoreRule -> Bool
isLocalRule = ru_local
+
+-- | Set the 'Name' of the 'Id.Id' at the head of the rule left hand side
+setRuleIdName :: Name -> CoreRule -> CoreRule
+setRuleIdName nm ru = ru { ru_fn = nm }
\end{code}
%* *
%************************************************************************
-The @Unfolding@ type is declared here to avoid numerous loops, but it
-should be abstract everywhere except in CoreUnfold.lhs
+The @Unfolding@ type is declared here to avoid numerous loops
\begin{code}
+-- | Records the /unfolding/ of an identifier, which is approximately the form the
+-- identifier would have if we substituted its definition in for the identifier.
+-- This type should be treated as abstract everywhere except in "CoreUnfold"
data Unfolding
- = NoUnfolding
+ = NoUnfolding -- ^ We have no information about the unfolding
- | OtherCon [AltCon] -- It ain't one of these
- -- (OtherCon xs) also indicates that something has been evaluated
+ | OtherCon [AltCon] -- ^ It ain't one of these constructors.
+ -- @OtherCon xs@ also indicates that something has been evaluated
-- and hence there's no point in re-evaluating it.
- -- OtherCon [] is used even for non-data-type values
+ -- @OtherCon []@ is used even for non-data-type values
-- to indicated evaluated-ness. Notably:
- -- data C = C !(Int -> Int)
- -- case x of { C f -> ... }
- -- Here, f gets an OtherCon [] unfolding.
-
- | CompulsoryUnfolding CoreExpr -- There is no "original" definition,
- -- so you'd better unfold.
-
- | CoreUnfolding -- An unfolding with redundant cached information
- CoreExpr -- Template; binder-info is correct
- Bool -- True <=> top level binding
- Bool -- exprIsHNF template (cached); it is ok to discard a `seq` on
+ --
+ -- > data C = C !(Int -> Int)
+ -- > case x of { C f -> ... }
+ --
+ -- Here, @f@ gets an @OtherCon []@ unfolding.
+
+ | CompulsoryUnfolding { -- There is /no original definition/, so you'd better unfold.
+ uf_tmpl :: CoreExpr -- The unfolding is guaranteed to have no free variables
+ } -- so no need to think about it during dependency analysis
+
+ | InlineRule { -- The function has an INLINE pragma, with the specified (original) RHS
+ -- (The inline phase, if any, is in the InlinePragInfo for this Id.)
+ -- Inline when (a) applied to at least this number of args
+ -- (b) if there is something interesting about args or context
+ uf_tmpl :: CoreExpr, -- The *original* RHS; occurrence info is correct
+ -- (The actual RHS of the function may be different by now,
+ -- but what we inline is still the original RHS (kept in the InlineRule).)
+ uf_is_top :: Bool,
+
+ uf_arity :: Arity, -- Don't inline unless applied to this number of *value* args
+ uf_is_value :: Bool, -- True <=> exprIsHNF is true; save to discard a `seq`
+ uf_worker :: Maybe Id -- Just wrk_id <=> this unfolding is a the wrapper in a worker/wrapper
+ -- split from the strictness analyser
+ -- Used to abbreviate the uf_tmpl in interface files
+ -- In the Just case, interface files don't actually
+ -- need to contain the RHS; it can be derived from
+ -- the strictness info
+ -- Also used in CoreUnfold to guide inlining decisions
+ }
+
+ | CoreUnfolding { -- An unfolding for an Id with no pragma, or perhaps a NOINLINE pragma
+ -- (For NOINLINE, the phase, if any, is in the InlinePragInfo for this Id.)
+ uf_tmpl :: CoreExpr, -- Template; binder-info is correct
+ uf_is_top :: Bool, -- True <=> top level binding
+ uf_is_value :: Bool, -- exprIsHNF template (cached); it is ok to discard a `seq` on
-- this variable
- Bool -- True <=> doesn't waste (much) work to expand inside an inlining
+ uf_is_cheap :: Bool, -- True <=> doesn't waste (much) work to expand inside an inlining
-- Basically it's exprIsCheap
- UnfoldingGuidance -- Tells about the *size* of the template.
-
-
+ uf_guidance :: UnfoldingGuidance -- Tells about the *size* of the template.
+ }
+ -- ^ An unfolding with redundant cached information. Parameters:
+ --
+ -- uf_tmpl: Template used to perform unfolding; binder-info is correct
+ --
+ -- uf_is_top: Is this a top level binding?
+ --
+ -- uf_is_valiue: 'exprIsHNF' template (cached); it is ok to discard a 'seq' on
+ -- this variable
+ --
+ -- uf_is_cheap: Does this waste only a little work if we expand it inside an inlining?
+ -- Basically this is a cached version of 'exprIsCheap'
+ --
+ -- uf_guidance: Tells us about the /size/ of the unfolding template
+
+------------------------------------------------
+-- | 'UnfoldingGuidance' says when unfolding should take place
data UnfoldingGuidance
= UnfoldNever
- | UnfoldIfGoodArgs Int -- and "n" value args
+ | UnfoldIfGoodArgs {
+ ug_arity :: Arity, -- "n" value args
+
+ ug_args :: [Int], -- Discount if the argument is evaluated.
+ -- (i.e., a simplification will definitely
+ -- be possible). One elt of the list per *value* arg.
- [Int] -- Discount if the argument is evaluated.
- -- (i.e., a simplification will definitely
- -- be possible). One elt of the list per *value* arg.
+ ug_size :: Int, -- The "size" of the unfolding; to be elaborated
+ -- later. ToDo
- Int -- The "size" of the unfolding; to be elaborated
- -- later. ToDo
+ ug_res :: Int -- Scrutinee discount: the discount to substract if the thing is in
+ } -- a context (case (thing args) of ...),
+ -- (where there are the right number of arguments.)
- Int -- Scrutinee discount: the discount to substract if the thing is in
- -- a context (case (thing args) of ...),
- -- (where there are the right number of arguments.)
+------------------------------------------------
+noUnfolding :: Unfolding
+-- ^ There is no known 'Unfolding'
+evaldUnfolding :: Unfolding
+-- ^ This unfolding marks the associated thing as being evaluated
noUnfolding = NoUnfolding
evaldUnfolding = OtherCon []
+mkOtherCon :: [AltCon] -> Unfolding
mkOtherCon = OtherCon
seqUnfolding :: Unfolding -> ()
-seqUnfolding (CoreUnfolding e top b1 b2 g)
+seqUnfolding (CoreUnfolding { uf_tmpl = e, uf_is_top = top,
+ uf_is_value = b1, uf_is_cheap = b2, uf_guidance = g})
= seqExpr e `seq` top `seq` b1 `seq` b2 `seq` seqGuidance g
-seqUnfolding other = ()
+seqUnfolding _ = ()
+seqGuidance :: UnfoldingGuidance -> ()
seqGuidance (UnfoldIfGoodArgs n ns a b) = n `seq` sum ns `seq` a `seq` b `seq` ()
-seqGuidance other = ()
+seqGuidance _ = ()
\end{code}
\begin{code}
+-- | Retrieves the template of an unfolding: panics if none is known
unfoldingTemplate :: Unfolding -> CoreExpr
-unfoldingTemplate (CoreUnfolding expr _ _ _ _) = expr
-unfoldingTemplate (CompulsoryUnfolding expr) = expr
-unfoldingTemplate other = panic "getUnfoldingTemplate"
+unfoldingTemplate = uf_tmpl
+
+setUnfoldingTemplate :: Unfolding -> CoreExpr -> Unfolding
+setUnfoldingTemplate unf rhs = unf { uf_tmpl = rhs }
+-- | Retrieves the template of an unfolding if possible
maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
-maybeUnfoldingTemplate (CoreUnfolding expr _ _ _ _) = Just expr
-maybeUnfoldingTemplate (CompulsoryUnfolding expr) = Just expr
-maybeUnfoldingTemplate other = Nothing
+maybeUnfoldingTemplate (CoreUnfolding { uf_tmpl = expr }) = Just expr
+maybeUnfoldingTemplate (CompulsoryUnfolding { uf_tmpl = expr }) = Just expr
+maybeUnfoldingTemplate (InlineRule { uf_tmpl = expr }) = Just expr
+maybeUnfoldingTemplate _ = Nothing
+-- | The constructors that the unfolding could never be:
+-- returns @[]@ if no information is available
otherCons :: Unfolding -> [AltCon]
otherCons (OtherCon cons) = cons
-otherCons other = []
+otherCons _ = []
+-- | Determines if it is certainly the case that the unfolding will
+-- yield a value (something in HNF): returns @False@ if unsure
isValueUnfolding :: Unfolding -> Bool
-- Returns False for OtherCon
-isValueUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
-isValueUnfolding other = False
+isValueUnfolding (CoreUnfolding { uf_is_value = is_evald }) = is_evald
+isValueUnfolding (InlineRule { uf_is_value = is_evald }) = is_evald
+isValueUnfolding _ = False
+-- | Determines if it possibly the case that the unfolding will
+-- yield a value. Unlike 'isValueUnfolding' it returns @True@
+-- for 'OtherCon'
isEvaldUnfolding :: Unfolding -> Bool
-- Returns True for OtherCon
-isEvaldUnfolding (OtherCon _) = True
-isEvaldUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
-isEvaldUnfolding other = False
+isEvaldUnfolding (OtherCon _) = True
+isEvaldUnfolding (CoreUnfolding { uf_is_value = is_evald }) = is_evald
+isEvaldUnfolding (InlineRule { uf_is_value = is_evald }) = is_evald
+isEvaldUnfolding _ = False
+-- | Is the thing we will unfold into certainly cheap?
isCheapUnfolding :: Unfolding -> Bool
-isCheapUnfolding (CoreUnfolding _ _ _ is_cheap _) = is_cheap
-isCheapUnfolding other = False
+isCheapUnfolding (CoreUnfolding { uf_is_cheap = is_cheap }) = is_cheap
+isCheapUnfolding _ = False
+isInlineRule :: Unfolding -> Bool
+isInlineRule (InlineRule {}) = True
+isInlineRule _ = False
+
+-- | Must this unfolding happen for the code to be executable?
isCompulsoryUnfolding :: Unfolding -> Bool
-isCompulsoryUnfolding (CompulsoryUnfolding _) = True
-isCompulsoryUnfolding other = False
+isCompulsoryUnfolding (CompulsoryUnfolding {}) = True
+isCompulsoryUnfolding _ = False
-hasUnfolding :: Unfolding -> Bool
-hasUnfolding (CoreUnfolding _ _ _ _ _) = True
-hasUnfolding (CompulsoryUnfolding _) = True
-hasUnfolding other = False
+isClosedUnfolding :: Unfolding -> Bool -- No free variables
+isClosedUnfolding (CoreUnfolding {}) = False
+isClosedUnfolding (InlineRule {}) = False
+isClosedUnfolding _ = True
+-- | Only returns False if there is no unfolding information available at all
hasSomeUnfolding :: Unfolding -> Bool
hasSomeUnfolding NoUnfolding = False
-hasSomeUnfolding other = True
+hasSomeUnfolding _ = True
+
+neverUnfoldGuidance :: UnfoldingGuidance -> Bool
+neverUnfoldGuidance UnfoldNever = True
+neverUnfoldGuidance _ = False
-neverUnfold :: Unfolding -> Bool
-neverUnfold NoUnfolding = True
-neverUnfold (OtherCon _) = True
-neverUnfold (CoreUnfolding _ _ _ _ UnfoldNever) = True
-neverUnfold other = False
+canUnfold :: Unfolding -> Bool
+canUnfold (InlineRule {}) = True
+canUnfold (CoreUnfolding { uf_guidance = g }) = not (neverUnfoldGuidance g)
+canUnfold _ = False
\end{code}
instance Outputable AltCon where
ppr (DataAlt dc) = ppr dc
ppr (LitAlt lit) = ppr lit
- ppr DEFAULT = ptext SLIT("__DEFAULT")
+ ppr DEFAULT = ptext (sLit "__DEFAULT")
instance Show AltCon where
showsPrec p con = showsPrecSDoc p (ppr con)
cmpAlt (con1, _, _) (con2, _, _) = con1 `cmpAltCon` con2
ltAlt :: Alt b -> Alt b -> Bool
-ltAlt a1 a2 = case a1 `cmpAlt` a2 of { LT -> True; other -> False }
+ltAlt a1 a2 = (a1 `cmpAlt` a2) == LT
cmpAltCon :: AltCon -> AltCon -> Ordering
--- Compares AltCons within a single list of alternatives
+-- ^ Compares 'AltCon's within a single list of alternatives
cmpAltCon DEFAULT DEFAULT = EQ
-cmpAltCon DEFAULT con = LT
+cmpAltCon DEFAULT _ = LT
cmpAltCon (DataAlt d1) (DataAlt d2) = dataConTag d1 `compare` dataConTag d2
cmpAltCon (DataAlt _) DEFAULT = GT
LT
\end{code}
-
%************************************************************************
%* *
\subsection{Useful synonyms}
%* *
%************************************************************************
-The common case
-
\begin{code}
+-- | The common case for the type of binders and variables when
+-- we are manipulating the Core language within GHC
type CoreBndr = Var
+-- | Expressions where binders are 'CoreBndr's
type CoreExpr = Expr CoreBndr
+-- | Argument expressions where binders are 'CoreBndr's
type CoreArg = Arg CoreBndr
+-- | Binding groups where binders are 'CoreBndr's
type CoreBind = Bind CoreBndr
+-- | Case alternatives where binders are 'CoreBndr's
type CoreAlt = Alt CoreBndr
\end{code}
-Binders are ``tagged'' with a \tr{t}:
+%************************************************************************
+%* *
+\subsection{Tagging}
+%* *
+%************************************************************************
\begin{code}
+-- | Binders are /tagged/ with a t
data TaggedBndr t = TB CoreBndr t -- TB for "tagged binder"
type TaggedBind t = Bind (TaggedBndr t)
%************************************************************************
\begin{code}
+-- | Apply a list of argument expressions to a function expression in a nested fashion. Prefer to
+-- use 'CoreUtils.mkCoreApps' if possible
mkApps :: Expr b -> [Arg b] -> Expr b
+-- | Apply a list of type argument expressions to a function expression in a nested fashion
mkTyApps :: Expr b -> [Type] -> Expr b
-mkValApps :: Expr b -> [Expr b] -> Expr b
+-- | Apply a list of type or value variables to a function expression in a nested fashion
mkVarApps :: Expr b -> [Var] -> Expr b
+-- | Apply a list of argument expressions to a data constructor in a nested fashion. Prefer to
+-- use 'MkCore.mkCoreConApps' if possible
+mkConApp :: DataCon -> [Arg b] -> Expr b
mkApps f args = foldl App f args
mkTyApps f args = foldl (\ e a -> App e (Type a)) f args
-mkValApps f args = foldl (\ e a -> App e a) f args
mkVarApps f vars = foldl (\ e a -> App e (varToCoreExpr a)) f vars
+mkConApp con args = mkApps (Var (dataConWorkId con)) args
+
-mkLit :: Literal -> Expr b
+-- | Create a machine integer literal expression of type @Int#@ from an @Integer@.
+-- If you want an expression of type @Int@ use 'MkCore.mkIntExpr'
mkIntLit :: Integer -> Expr b
+-- | Create a machine integer literal expression of type @Int#@ from an @Int@.
+-- If you want an expression of type @Int@ use 'MkCore.mkIntExpr'
mkIntLitInt :: Int -> Expr b
-mkConApp :: DataCon -> [Arg b] -> Expr b
+
+mkIntLit n = Lit (mkMachInt n)
+mkIntLitInt n = Lit (mkMachInt (toInteger n))
+
+-- | Create a machine word literal expression of type @Word#@ from an @Integer@.
+-- If you want an expression of type @Word@ use 'MkCore.mkWordExpr'
+mkWordLit :: Integer -> Expr b
+-- | Create a machine word literal expression of type @Word#@ from a @Word@.
+-- If you want an expression of type @Word@ use 'MkCore.mkWordExpr'
+mkWordLitWord :: Word -> Expr b
+
+mkWordLit w = Lit (mkMachWord w)
+mkWordLitWord w = Lit (mkMachWord (toInteger w))
+
+-- | Create a machine character literal expression of type @Char#@.
+-- If you want an expression of type @Char@ use 'MkCore.mkCharExpr'
+mkCharLit :: Char -> Expr b
+-- | Create a machine string literal expression of type @Addr#@.
+-- If you want an expression of type @String@ use 'MkCore.mkStringExpr'
+mkStringLit :: String -> Expr b
+
+mkCharLit c = Lit (mkMachChar c)
+mkStringLit s = Lit (mkMachString s)
+
+-- | Create a machine single precision literal expression of type @Float#@ from a @Rational@.
+-- If you want an expression of type @Float@ use 'MkCore.mkFloatExpr'
+mkFloatLit :: Rational -> Expr b
+-- | Create a machine single precision literal expression of type @Float#@ from a @Float@.
+-- If you want an expression of type @Float@ use 'MkCore.mkFloatExpr'
+mkFloatLitFloat :: Float -> Expr b
+
+mkFloatLit f = Lit (mkMachFloat f)
+mkFloatLitFloat f = Lit (mkMachFloat (toRational f))
+
+-- | Create a machine double precision literal expression of type @Double#@ from a @Rational@.
+-- If you want an expression of type @Double@ use 'MkCore.mkDoubleExpr'
+mkDoubleLit :: Rational -> Expr b
+-- | Create a machine double precision literal expression of type @Double#@ from a @Double@.
+-- If you want an expression of type @Double@ use 'MkCore.mkDoubleExpr'
+mkDoubleLitDouble :: Double -> Expr b
+
+mkDoubleLit d = Lit (mkMachDouble d)
+mkDoubleLitDouble d = Lit (mkMachDouble (toRational d))
+
+-- | Bind all supplied binding groups over an expression in a nested let expression. Prefer to
+-- use 'CoreUtils.mkCoreLets' if possible
mkLets :: [Bind b] -> Expr b -> Expr b
+-- | Bind all supplied binders over an expression in a nested lambda expression. Prefer to
+-- use 'CoreUtils.mkCoreLams' if possible
mkLams :: [b] -> Expr b -> Expr b
-mkLit lit = Lit lit
-mkConApp con args = mkApps (Var (dataConWorkId con)) args
-
mkLams binders body = foldr Lam body binders
mkLets binds body = foldr Let body binds
-mkIntLit n = Lit (mkMachInt n)
-mkIntLitInt n = Lit (mkMachInt (toInteger n))
+-- | Create a binding group where a type variable is bound to a type. Per "CoreSyn#type_let",
+-- this can only be used to bind something in a non-recursive @let@ expression
+mkTyBind :: TyVar -> Type -> CoreBind
+mkTyBind tv ty = NonRec tv (Type ty)
+
+-- | Convert a binder into either a 'Var' or 'Type' 'Expr' appropriately
varToCoreExpr :: CoreBndr -> Expr b
-varToCoreExpr v | isId v = Var v
+varToCoreExpr v | isIdVar v = Var v
| otherwise = Type (mkTyVarTy v)
+
+varsToCoreExprs :: [CoreBndr] -> [Expr b]
+varsToCoreExprs vs = map varToCoreExpr vs
\end{code}
%************************************************************************
\begin{code}
+-- | Extract every variable by this group
bindersOf :: Bind b -> [b]
bindersOf (NonRec binder _) = [binder]
bindersOf (Rec pairs) = [binder | (binder, _) <- pairs]
+-- | 'bindersOf' applied to a list of binding groups
bindersOfBinds :: [Bind b] -> [b]
bindersOfBinds binds = foldr ((++) . bindersOf) [] binds
rhssOfAlts :: [Alt b] -> [Expr b]
rhssOfAlts alts = [e | (_,_,e) <- alts]
-flattenBinds :: [Bind b] -> [(b, Expr b)] -- Get all the lhs/rhs pairs
+-- | Collapse all the bindings in the supplied groups into a single
+-- list of lhs\/rhs pairs suitable for binding in a 'Rec' binding group
+flattenBinds :: [Bind b] -> [(b, Expr b)]
flattenBinds (NonRec b r : binds) = (b,r) : flattenBinds binds
flattenBinds (Rec prs1 : binds) = prs1 ++ flattenBinds binds
flattenBinds [] = []
\end{code}
-We often want to strip off leading lambdas before getting down to
-business. @collectBinders@ is your friend.
-
-We expect (by convention) type-, and value- lambdas in that
-order.
-
\begin{code}
+-- | We often want to strip off leading lambdas before getting down to
+-- business. This function is your friend.
collectBinders :: Expr b -> ([b], Expr b)
+-- | Collect as many type bindings as possible from the front of a nested lambda
collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)
+-- | Collect as many value bindings as possible from the front of a nested lambda
collectValBinders :: CoreExpr -> ([Id], CoreExpr)
+-- | Collect type binders from the front of the lambda first,
+-- then follow up by collecting as many value bindings as possible
+-- from the resulting stripped expression
collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)
collectBinders expr
collectValBinders expr
= go [] expr
where
- go ids (Lam b e) | isId b = go (b:ids) e
- go ids body = (reverse ids, body)
+ go ids (Lam b e) | isIdVar b = go (b:ids) e
+ go ids body = (reverse ids, body)
\end{code}
-
-@collectArgs@ takes an application expression, returning the function
-and the arguments to which it is applied.
-
\begin{code}
+-- | Takes a nested application expression and returns the the function
+-- being applied and the arguments to which it is applied
collectArgs :: Expr b -> (Expr b, [Arg b])
collectArgs expr
= go expr []
go e as = (e, as)
\end{code}
-coreExprCc gets the cost centre enclosing an expression, if any.
-It looks inside lambdas because (scc "foo" \x.e) = \x.scc "foo" e
-
\begin{code}
+-- | Gets the cost centre enclosing an expression, if any.
+-- It looks inside lambdas because @(scc \"foo\" \\x.e) = \\x. scc \"foo\" e@
coreExprCc :: Expr b -> CostCentre
-coreExprCc (Note (SCC cc) e) = cc
-coreExprCc (Note other_note e) = coreExprCc e
+coreExprCc (Note (SCC cc) _) = cc
+coreExprCc (Note _ e) = coreExprCc e
coreExprCc (Lam _ e) = coreExprCc e
-coreExprCc other = noCostCentre
+coreExprCc _ = noCostCentre
\end{code}
-
-
%************************************************************************
%* *
\subsection{Predicates}
%* *
%************************************************************************
+At one time we optionally carried type arguments through to runtime.
@isRuntimeVar v@ returns if (Lam v _) really becomes a lambda at runtime,
i.e. if type applications are actual lambdas because types are kept around
-at runtime.
-
-Similarly isRuntimeArg.
+at runtime. Similarly isRuntimeArg.
\begin{code}
+-- | Will this variable exist at runtime?
isRuntimeVar :: Var -> Bool
-isRuntimeVar | opt_RuntimeTypes = \v -> True
- | otherwise = \v -> isId v
+isRuntimeVar = isIdVar
+-- | Will this argument expression exist at runtime?
isRuntimeArg :: CoreExpr -> Bool
-isRuntimeArg | opt_RuntimeTypes = \e -> True
- | otherwise = \e -> isValArg e
-\end{code}
+isRuntimeArg = isValArg
-\begin{code}
+-- | Returns @False@ iff the expression is a 'Type' expression at its top level
+isValArg :: Expr b -> Bool
isValArg (Type _) = False
-isValArg other = True
+isValArg _ = True
+-- | Returns @True@ iff the expression is a 'Type' expression at its top level
+isTypeArg :: Expr b -> Bool
isTypeArg (Type _) = True
-isTypeArg other = False
+isTypeArg _ = False
+-- | The number of binders that bind values rather than types
valBndrCount :: [CoreBndr] -> Int
-valBndrCount [] = 0
-valBndrCount (b : bs) | isId b = 1 + valBndrCount bs
- | otherwise = valBndrCount bs
+valBndrCount = count isIdVar
+-- | The number of argument expressions that are values rather than types at their top level
valArgCount :: [Arg b] -> Int
-valArgCount [] = 0
-valArgCount (Type _ : args) = valArgCount args
-valArgCount (other : args) = 1 + valArgCount args
+valArgCount = count isValArg
\end{code}
seqExpr (App f a) = seqExpr f `seq` seqExpr a
seqExpr (Lam b e) = seqBndr b `seq` seqExpr e
seqExpr (Let b e) = seqBind b `seq` seqExpr e
--- gaw 2004
seqExpr (Case e b t as) = seqExpr e `seq` seqBndr b `seq` seqType t `seq` seqAlts as
+seqExpr (Cast e co) = seqExpr e `seq` seqType co
seqExpr (Note n e) = seqNote n `seq` seqExpr e
seqExpr (Type t) = seqType t
+seqExprs :: [CoreExpr] -> ()
seqExprs [] = ()
seqExprs (e:es) = seqExpr e `seq` seqExprs es
-seqNote (Coerce t1 t2) = seqType t1 `seq` seqType t2
+seqNote :: Note -> ()
seqNote (CoreNote s) = s `seq` ()
-seqNote other = ()
+seqNote _ = ()
+seqBndr :: CoreBndr -> ()
seqBndr b = b `seq` ()
+seqBndrs :: [CoreBndr] -> ()
seqBndrs [] = ()
seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
+seqBind :: Bind CoreBndr -> ()
seqBind (NonRec b e) = seqBndr b `seq` seqExpr e
seqBind (Rec prs) = seqPairs prs
+seqPairs :: [(CoreBndr, CoreExpr)] -> ()
seqPairs [] = ()
seqPairs ((b,e):prs) = seqBndr b `seq` seqExpr e `seq` seqPairs prs
+seqAlts :: [CoreAlt] -> ()
seqAlts [] = ()
-seqAlts ((c,bs,e):alts) = seqBndrs bs `seq` seqExpr e `seq` seqAlts alts
+seqAlts ((c,bs,e):alts) = c `seq` seqBndrs bs `seq` seqExpr e `seq` seqAlts alts
+seqRules :: [CoreRule] -> ()
seqRules [] = ()
seqRules (Rule { ru_bndrs = bndrs, ru_args = args, ru_rhs = rhs } : rules)
= seqBndrs bndrs `seq` seqExprs (rhs:args) `seq` seqRules rules
seqRules (BuiltinRule {} : rules) = seqRules rules
\end{code}
-
-
%************************************************************************
%* *
-\subsection{Annotated core; annotation at every node in the tree}
+\subsection{Annotated core}
%* *
%************************************************************************
\begin{code}
+-- | Annotated core: allows annotation at every node in the tree
type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)
+-- | A clone of the 'Expr' type but allowing annotation at every tree node
data AnnExpr' bndr annot
= AnnVar Id
| AnnLit Literal
| AnnLam bndr (AnnExpr bndr annot)
| AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot)
--- gaw 2004
| AnnCase (AnnExpr bndr annot) bndr Type [AnnAlt bndr annot]
| AnnLet (AnnBind bndr annot) (AnnExpr bndr annot)
+ | AnnCast (AnnExpr bndr annot) Coercion
| AnnNote Note (AnnExpr bndr annot)
| AnnType Type
+-- | A clone of the 'Alt' type but allowing annotation at every tree node
type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)
+-- | A clone of the 'Bind' type but allowing annotation at every tree node
data AnnBind bndr annot
= AnnNonRec bndr (AnnExpr bndr annot)
| AnnRec [(bndr, AnnExpr bndr annot)]
deAnnotate :: AnnExpr bndr annot -> Expr bndr
deAnnotate (_, e) = deAnnotate' e
+deAnnotate' :: AnnExpr' bndr annot -> Expr bndr
deAnnotate' (AnnType t) = Type t
deAnnotate' (AnnVar v) = Var v
deAnnotate' (AnnLit lit) = Lit lit
deAnnotate' (AnnLam binder body) = Lam binder (deAnnotate body)
deAnnotate' (AnnApp fun arg) = App (deAnnotate fun) (deAnnotate arg)
+deAnnotate' (AnnCast e co) = Cast (deAnnotate e) co
deAnnotate' (AnnNote note body) = Note note (deAnnotate body)
deAnnotate' (AnnLet bind body)
deAnnBind (AnnNonRec var rhs) = NonRec var (deAnnotate rhs)
deAnnBind (AnnRec pairs) = Rec [(v,deAnnotate rhs) | (v,rhs) <- pairs]
--- gaw 2004
deAnnotate' (AnnCase scrut v t alts)
= Case (deAnnotate scrut) v t (map deAnnAlt alts)
\end{code}
\begin{code}
+-- | As 'collectBinders' but for 'AnnExpr' rather than 'Expr'
collectAnnBndrs :: AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
collectAnnBndrs e
= collect [] e
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