1. 31 Oct, 2000 3 commits
  2. 30 Oct, 2000 2 commits
  3. 25 Oct, 2000 1 commit
  4. 24 Oct, 2000 4 commits
  5. 23 Oct, 2000 2 commits
  6. 19 Oct, 2000 1 commit
  7. 18 Oct, 2000 1 commit
  8. 17 Oct, 2000 1 commit
  9. 16 Oct, 2000 1 commit
  10. 13 Oct, 2000 2 commits
  11. 12 Oct, 2000 4 commits
  12. 03 Oct, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-10-03 08:43:00 by simonpj] · 710e2074
      simonpj authored
      --------------------------------------
      	Adding generics		SLPJ Oct 2000
      	--------------------------------------
      
      This big commit adds Hinze/PJ-style generic class definitions, based
      on work by Andrei Serjantov.  For example:
      
        class Bin a where
          toBin   :: a -> [Int]
          fromBin :: [Int] -> (a, [Int])
      
          toBin {| Unit |}    Unit	  = []
          toBin {| a :+: b |} (Inl x)   = 0 : toBin x
          toBin {| a :+: b |} (Inr y)   = 1 : toBin y
          toBin {| a :*: b |} (x :*: y) = toBin x ++ toBin y
      
      
          fromBin {| Unit |}    bs      = (Unit, bs)
          fromBin {| a :+: b |} (0:bs)  = (Inl x, bs')    where (x,bs') = fromBin bs
          fromBin {| a :+: b |} (1:bs)  = (Inr y, bs')    where (y,bs') = fromBin bs
          fromBin {| a :*: b |} bs  	  = (x :*: y, bs'') where (x,bs' ) = fromBin bs
      							  (y,bs'') = fromBin bs'
      
      Now we can say simply
      
        instance Bin a => Bin [a]
      
      and the compiler will derive the appropriate code automatically.
      
      		(About 9k lines of diffs.  Ha!)
      
      
      Generic related things
      ~~~~~~~~~~~~~~~~~~~~~~
      
      * basicTypes/BasicTypes: The EP type (embedding-projection pairs)
      
      * types/TyCon:
      	An extra field in an algebraic tycon (genInfo)
      
      * types/Class, and hsSyn/HsBinds:
      	Each class op (or ClassOpSig) carries information about whether
      	it  	a) has no default method
      		b) has a polymorphic default method
      		c) has a generic default method
      	There's a new data type for this: Class.DefMeth
      
      * types/Generics:
      	A new module containing good chunk of the generic-related code
      	It has a .hi-boot file (alas).
      
      * typecheck/TcInstDcls, typecheck/TcClassDcl:
      	Most of the rest of the generics-related code
      
      * hsSyn/HsTypes:
      	New infix type form to allow types of the form
      		data a :+: b = Inl a | Inr b
      
      * parser/Parser.y, Lex.lhs, rename/ParseIface.y:
      	Deal with the new syntax
      
      * prelude/TysPrim, TysWiredIn:
      	Need to generate generic stuff for the wired-in TyCons
      
      * rename/RnSource RnBinds:
      	A rather gruesome hack to deal with scoping of type variables
      	from a generic patterns.  Details commented in the ClassDecl
      	case of RnSource.rnDecl.
      
      	Of course, there are many minor renamer consequences of the
      	other changes above.
      
      * lib/std/PrelBase.lhs
      	Data type declarations for Unit, :+:, :*:
      
      
      Slightly unrelated housekeeping
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * hsSyn/HsDecls:
      	ClassDecls now carry the Names for their implied declarations
      	(superclass selectors, tycon, etc) in a list, rather than
      	laid out one by one.  This simplifies code between the parser
      	and the type checker.
      
      * prelude/PrelNames, TysWiredIn:
      	All the RdrNames are now together in PrelNames.
      
      * utils/ListSetOps:
      	Add finite mappings based on equality and association lists (Assoc a b)
      	Move stuff from List.lhs that is related
      710e2074
  13. 28 Sep, 2000 2 commits
    • simonpj's avatar
      [project @ 2000-09-28 15:15:48 by simonpj] · fa67ca4d
      simonpj authored
      Wibbles
      fa67ca4d
    • simonpj's avatar
      [project @ 2000-09-28 13:04:14 by simonpj] · 861e836e
      simonpj authored
      ------------------------------------
      	   Mainly PredTypes (28 Sept 00)
      	------------------------------------
      
      Three things in this commit:
      
      	1.  Main thing: tidy up PredTypes
      	2.  Move all Keys into PrelNames
      	3.  Check for unboxed tuples in function args
      
      1. Tidy up PredTypes
      ~~~~~~~~~~~~~~~~~~~~
      The main thing in this commit is to modify the representation of Types
      so that they are a (much) better for the qualified-type world.  This
      should simplify Jeff's life as he proceeds with implicit parameters
      and functional dependencies.  In particular, PredType, introduced by
      Jeff, is now blessed and dignified with a place in TypeRep.lhs:
      
      	data PredType  = Class  Class [Type]
      		       | IParam Name  Type
      
      Consider these examples:
      	f :: (Eq a) => a -> Int
      	g :: (?x :: Int -> Int) => a -> Int
      	h :: (r\l) => {r} => {l::Int | r}
      
      Here the "Eq a" and "?x :: Int -> Int" and "r\l" are all called
      *predicates*, and are represented by a PredType.  (We don't support
      TREX records yet, but the setup is designed to expand to allow them.)
      
      In addition, Type gains an extra constructor:
      
      	data Type = .... | PredTy PredType
      
      so that PredType is injected directly into Type.  So the type
      	p => t
      is represented by
      	PredType p `FunTy` t
      
      I have deleted the hackish IPNote stuff; predicates are dealt with entirely
      through PredTys, not through NoteTy at all.
      
      
      2.  Move Keys into PrelNames
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      This is just a housekeeping operation. I've moved all the pre-assigned Uniques
      (aka Keys) from Unique.lhs into PrelNames.lhs.  I've also moved knowKeyRdrNames
      from PrelInfo down into PrelNames.  This localises in PrelNames lots of stuff
      about predefined names.  Previously one had to alter three files to add one,
      now only one.
      
      3.  Unboxed tuples
      ~~~~~~~~~~~~~~~~~~
      Add a static check for unboxed tuple arguments.  E.g.
      	data T = T (# Int, Int #)
      is illegal
      861e836e
  14. 22 Sep, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-09-22 15:56:12 by simonpj] · 1bba522f
      simonpj authored
      --------------------------------------------------
      	Tidying up HsLit, and making it possible to define
      		your own numeric library
      
      		Simon PJ 22 Sept 00
      	--------------------------------------------------
      
      ** NOTE: I did these changes on the aeroplane.  They should compile,
      	 and the Prelude still compiles OK, but it's entirely 
      	 possible that I've broken something
      
      The original reason for this many-file but rather shallow
      commit is that it's impossible in Haskell to write your own
      numeric library.  Why?  Because when you say '1' you get 
      (Prelude.fromInteger 1), regardless of what you hide from the
      Prelude, or import from other libraries you have written.  So the
      idea is to extend the -fno-implicit-prelude flag so that 
      in addition to no importing the Prelude, you can rebind 
      	fromInteger	-- Applied to literal constants
      	fromRational	-- Ditto
      	negate		-- Invoked by the syntax (-x)
      	the (-) used when desugaring n+k patterns
      
      After toying with other designs, I eventually settled on a simple,
      crude one: rather than adding a new flag, I just extended the
      semantics of -fno-implicit-prelude so that uses of fromInteger,
      fromRational and negate are all bound to "whatever is in scope" 
      rather than "the fixed Prelude functions".  So if you say
      
      	{-# OPTIONS -fno-implicit-prelude #-}
      	module M where
       	import MyPrelude( fromInteger )
      
      	x = 3
      
      the literal 3 will use whatever (unqualified) "fromInteger" is in scope,
      in this case the one gotten from MyPrelude.
      
      
      On the way, though, I studied how HsLit worked, and did a substantial tidy
      up, deleting quite a lot of code along the way.  In particular.
      
      * HsBasic.lhs is renamed HsLit.lhs.  It defines the HsLit type.
      
      * There are now two HsLit types, both defined in HsLit.
      	HsLit for non-overloaded literals (like 'x')
      	HsOverLit for overloaded literals (like 1 and 2.3)
      
      * HsOverLit completely replaces Inst.OverloadedLit, which disappears.
        An HsExpr can now be an HsOverLit as well as an HsLit.
      
      * HsOverLit carries the Name of the fromInteger/fromRational operation,
        so that the renamer can help with looking up the unqualified name 
        when -fno-implicit-prelude is on.  Ditto the HsExpr for negation.
        It's all very tidy now.
      
      * RdrHsSyn contains the stuff that handles -fno-implicit-prelude
        (see esp RdrHsSyn.prelQual).  RdrHsSyn also contains all the "smart constructors"
        used by the parser when building HsSyn.  See for example RdrHsSyn.mkNegApp
        (previously the renamer (!) did the business of turning (- 3#) into -3#).
      
      * I tidied up the handling of "special ids" in the parser.  There's much
        less duplication now.
      
      * Move Sven's Horner stuff to the desugarer, where it belongs.  
        There's now a nice function DsUtils.mkIntegerLit which brings together
        related code from no fewer than three separate places into one single
        place.  Nice!
      
      * A nice tidy-up in MatchLit.partitionEqnsByLit became possible.
      
      * Desugaring of HsLits is now much tidier (DsExpr.dsLit)
      
      * Some stuff to do with RdrNames is moved from ParseUtil.lhs to RdrHsSyn.lhs,
        which is where it really belongs.
      
      * I also removed 
      	many unnecessary imports from modules 
      	quite a bit of dead code
        in divers places
      1bba522f
  15. 07 Sep, 2000 1 commit
  16. 01 Aug, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-08-01 09:08:25 by simonpj] · fe69f3c1
      simonpj authored
      Simon's Marktoberdorf Commits
      
      1.  Tidy up the renaming story for "system binders", such as
      dictionary functions, default methods, constructor workers etc.  These
      are now documented in HsDecls.  The main effect of the change, apart
      from tidying up, is to make the *type-checker* (instead of the
      renamer) generate names for dict-funs and default-methods.  This is
      good because Sergei's generic-class stuff generates new classes at
      typecheck time.
      
      
      2.  Fix the CSE pass so it does not require the no-shadowing invariant.
      Keith discovered that the simplifier occasionally returns a result
      with shadowing.  After much fiddling around (which has improved the
      code in the simplifier a bit) I found that it is nearly impossible to
      arrange that it really does do no-shadowing.  So I gave up and fixed
      the CSE pass (which is the only one to rely on it) instead.
      
      
      3. Fix a performance bug in the simplifier.  The change is in
      SimplUtils.interestingArg.  It computes whether an argment should 
      be considered "interesting"; if a function is applied to an interesting
      argument, we are more likely to inline that function.
      Consider this case
      	let x = 3 in f x
      The 'x' argument was considered "uninteresting" for a silly reason.
      Since x only occurs once, it was unconditionally substituted, but
      interestingArg didn't take account of that case.  Now it does.
      
      I also made interestingArg a bit more liberal.  Let's see if we
      get too much inlining now.
      
      
      4.  In the occurrence analyser, we were choosing a bad loop breaker.
      Here's the comment that's now in OccurAnal.reOrderRec
      
          score ((bndr, rhs), _, _)
      	| exprIsTrivial rhs 	   = 3	-- Practically certain to be inlined
      		-- Used to have also: && not (isExportedId bndr)
      		-- But I found this sometimes cost an extra iteration when we have
      		--	rec { d = (a,b); a = ...df...; b = ...df...; df = d }
      		-- where df is the exported dictionary. Then df makes a really
      		-- bad choice for loop breaker
      
      I also increased the score for bindings with a non-functional type, so that
      dictionaries have a better chance of getting inlined early
      
      
      5. Add a hash code to the InScopeSet (and make it properly abstract)
      This should make uniqAway a lot more robust.  Simple experiments suggest
      that uniqAway no longer gets into the long iteration chains that it used
      to.
      
      
      6.  Fix a bug in the inliner that made the simplifier tend to get into
      a loop where it would keep iterating ("4 iterations, bailing out" message).
      In SimplUtils.mkRhsTyLam we float bindings out past a big lambda, thus:
      	x = /\ b -> let g = \x -> f x x
      		    in E
      becomes
      	g* = /\a -> \x -> f x x
      	x = /\ b -> let g = g* b in E
      	
      It's essential that we don't simply inling g* back into the RHS of g,
      else we will be back to square 1.  The inliner is meant not to do this
      because there's no benefit to the inlining, but the size calculation
      was a little off in CoreUnfold.
      
      
      7.  In SetLevels we were bogus-ly building a Subst with an empty in-scope
      set, so a WARNING popped up when compiling some modules.  (knights/ChessSetList
      was the example that tickled it.)  Now in fact the warning wasn't an error,
      but the Right Thing to do is to carry down a proper Subst in SetLevels, so
      that is what I have now done.  It is very little more expensive.
      fe69f3c1
  17. 14 Jul, 2000 2 commits
    • simonpj's avatar
      [project @ 2000-07-14 13:37:53 by simonpj] · 71352675
      simonpj authored
      Wibbles in the new kind-checking stuff
      71352675
    • simonpj's avatar
      [project @ 2000-07-14 08:17:36 by simonpj] · 77a8c0db
      simonpj authored
      This commit completely re-does the kind-inference mechanism.
      Previously it was inter-wound with type inference, but that was
      always hard to understand, and it finally broke when we started
      checking for ambiguity when type-checking a type signature (details
      irrelevant).
      
      So now kind inference is more clearly separated, so that it never
      takes place at the same time as type inference.  The biggest change
      is in TcTyClsDecls, which does the kind inference for a group of
      type and class declarations.  It now contains comments to explain
      how it all works.
      
      There are also comments in TypeRep which describes the slightly
      tricky way in which we deal with the fact that kind 'type' (written
      '*') actually has 'boxed type' and 'unboxed type' as sub-kinds.
      The whole thing is a bit of a hack, because we don't really have 
      sub-kinding, but it's less of a hack than before.
      
      A lot of general tidying up happened at the same time.
      In particular, I removed some dead code here and there
      77a8c0db
  18. 11 Jul, 2000 1 commit
  19. 07 Jul, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-07-07 12:13:43 by simonpj] · 7bb06950
      simonpj authored
      This commit moves the instance environment out of the Class data
      structure, where it was immutable, to part of the type-checker
      environment.  This change is absolutely essential as part of
      our move to GHCi, and I think it's also going to be necessary
      for Andrei's work on generic functions.
      
      As part of this change, we can remove
      
        a) types/InstEnv.*	(thereby also removing a hi-boot loop)
        b) a tc-fixpoint-loop in TcModule
      
      Both of these are worthwhile simplifications.
      7bb06950
  20. 25 May, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-05-25 12:41:14 by simonpj] · 495ef8bd
      simonpj authored
      ~~~~~~~~~~~~
      		Apr/May 2000
      		~~~~~~~~~~~~
      
      This is a pretty big commit!  It adds stuff I've been working on
      over the last month or so.  DO NOT MERGE IT WITH 4.07!
      
      Interface file formats have changed a little; you'll need
      to make clean before remaking.
      
      						Simon PJ
      
      Recompilation checking
      ~~~~~~~~~~~~~~~~~~~~~~
      Substantial improvement in recompilation checking.  The version management
      is now entirely internal to GHC.  ghc-iface.lprl is dead!
      
      The trick is to generate the new interface file in two steps:
        - first convert Types etc to HsTypes etc, and thereby
      	build a new ParsedIface
        - then compare against the parsed (but not renamed) version of the old
      	interface file
      Doing this meant adding code to convert *to* HsSyn things, and to
      compare HsSyn things for equality.  That is the main tedious bit.
      
      Another improvement is that we now track version info for
      fixities and rules, which was missing before.
      
      
      Interface file reading
      ~~~~~~~~~~~~~~~~~~~~~~
      Make interface files reading more robust.
        * If the old interface file is unreadable, don't fail. [bug fix]
      
        * If the old interface file mentions interfaces
          that are unreadable, don't fail. [bug fix]
      
        * When we can't find the interface file,
          print the directories we are looking in.  [feature]
      
      
      Type signatures
      ~~~~~~~~~~~~~~~
        * New flag -ddump-types to print type signatures
      
      
      Type pruning
      ~~~~~~~~~~~~
      When importing
      	data T = T1 A | T2 B | T3 C
      it seems excessive to import the types A, B, C as well, unless
      the constructors T1, T2 etc are used.  A,B,C might be more types,
      and importing them may mean reading more interfaces, and so on.
       So the idea is that the renamer will just import the decl
      	data T
      unless one of the constructors is used.  This turns out to be quite
      easy to implement.  The downside is that we must make sure the
      constructors are always available if they are really needed, so
      I regard this as an experimental feature.
      
      
      Elimininate ThinAir names
      ~~~~~~~~~~~~~~~~~~~~~~~~~
      Eliminate ThinAir.lhs and all its works.  It was always a hack, and now
      the desugarer carries around an environment I think we can nuke ThinAir
      altogether.
      
      As part of this, I had to move all the Prelude RdrName defns from PrelInfo
      to PrelMods --- so I renamed PrelMods as PrelNames.
      
      I also had to move the builtinRules so that they are injected by the renamer
      (rather than appearing out of the blue in SimplCore).  This is if anything simpler.
      
      Miscellaneous
      ~~~~~~~~~~~~~
      * Tidy up the data types involved in Rules
      
      * Eliminate RnEnv.better_provenance; use Name.hasBetterProv instead
      
      * Add Unique.hasKey :: Uniquable a => a -> Unique -> Bool
        It's useful in a lot of places
      
      * Fix a bug in interface file parsing for __U[!]
      495ef8bd
  21. 23 May, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-05-23 11:35:36 by simonpj] · bb91427f
      simonpj authored
      *** MERGE WITH 4.07 (once I've checked it works) ***
      
      * Fix result type signatures.  Note that a consequential change is that
        an ordinary binding with a variable on the left
      	f = e
        is now treated as a FunMonoBind, not a PatMonoBind.  This makes
        a few things a bit simpler (eg rnMethodBinds)
      
      * Fix warnings for unused imports.  This meant moving where provenances
        are improved in RnNames.  Move mkExportAvails from RnEnv to RnNames.
      
      * Print module names right (small change in Module.lhs and Rename.lhs)
      
      * Remove a few unused bindings
        
      * Add a little hack to let us print info about join points that turn
        out not to be let-no-escaped.  The idea is to call them "$j" and report
        any such variables that are not let-no-escaped.
      
      * Some small things aiming towards -ddump-types (harmless but incomplete)
      bb91427f
  22. 23 Mar, 2000 1 commit
    • simonpj's avatar
      [project @ 2000-03-23 17:45:17 by simonpj] · 111cee3f
      simonpj authored
      This utterly gigantic commit is what I've been up to in background
      mode in the last couple of months.  Originally the main goal
      was to get rid of Con (staturated constant applications)
      in the CoreExpr type, but one thing led to another, and I kept
      postponing actually committing.   Sorry.
      
      	Simon, 23 March 2000
      
      
      I've tested it pretty thoroughly, but doubtless things will break.
      
      Here are the highlights
      
      * Con is gone; the CoreExpr type is simpler
      * NoRepLits have gone
      * Better usage info in interface files => less recompilation
      * Result type signatures work
      * CCall primop is tidied up
      * Constant folding now done by Rules
      * Lots of hackery in the simplifier
      * Improvements in CPR and strictness analysis
      
      Many bug fixes including
      
      * Sergey's DoCon compiles OK; no loop in the strictness analyser
      * Volker Wysk's programs don't crash the CPR analyser
      
      I have not done much on measuring compilation times and binary sizes;
      they could have got worse.  I think performance has got significantly
      better, though, in most cases.
      
      
      Removing the Con form of Core expressions
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      The big thing is that
      
        For every constructor C there are now *two* Ids:
      
      	C is the constructor's *wrapper*. It evaluates and unboxes arguments
      	before calling $wC.  It has a perfectly ordinary top-level defn
      	in the module defining the data type.
      
      	$wC is the constructor's *worker*.  It is like a primop that simply
      	allocates and builds the constructor value.  Its arguments are the
      	actual representation arguments of the constructor.
      	Its type may be different to C, because:
      		- useless dict args are dropped
      		- strict args may be flattened
      
        For every primop P there is *one* Id, its (curried) Id
      
        Neither contructor worker Id nor the primop Id have a defminition anywhere.
        Instead they are saturated during the core-to-STG pass, and the code generator
        generates code for them directly. The STG language still has saturated
        primops and constructor applications.
      
      * The Const type disappears, along with Const.lhs.  The literal part
        of Const.lhs reappears as Literal.lhs.  Much tidying up in here,
        to bring all the range checking into this one module.
      
      * I got rid of NoRep literals entirely.  They just seem to be too much trouble.
      
      * Because Con's don't exist any more, the funny C { args } syntax
        disappears from inteface files.
      
      
      Parsing
      ~~~~~~~
      * Result type signatures now work
      	f :: Int -> Int = \x -> x
      	-- The Int->Int is the type of f
      
      	g x y :: Int = x+y
      	-- The Int is the type of the result of (g x y)
      
      
      Recompilation checking and make
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * The .hi file for a modules is not touched if it doesn't change.  (It used to
        be touched regardless, forcing a chain of recompilations.)  The penalty for this
        is that we record exported things just as if they were mentioned in the body of
        the module.  And the penalty for that is that we may recompile a module when
        the only things that have changed are the things it is passing on without using.
        But it seems like a good trade.
      
      * -recomp is on by default
      
      Foreign declarations
      ~~~~~~~~~~~~~~~~~~~~
      * If you say
      	foreign export zoo :: Int -> IO Int
        then you get a C produre called 'zoo', not 'zzoo' as before.
        I've also added a check that complains if you export (or import) a C
        procedure whose name isn't legal C.
      
      
      Code generation and labels
      ~~~~~~~~~~~~~~~~~~~~~~~~~~
      * Now that constructor workers and wrappers have distinct names, there's
        no need to have a Foo_static_closure and a Foo_closure for constructor Foo.
        I nuked the entire StaticClosure story.  This has effects in some of
        the RTS headers (i.e. s/static_closure/closure/g)
      
      
      Rules, constant folding
      ~~~~~~~~~~~~~~~~~~~~~~~
      * Constant folding becomes just another rewrite rule, attached to the Id for the
        PrimOp.   To achieve this, there's a new form of Rule, a BuiltinRule (see CoreSyn.lhs).
        The prelude rules are in prelude/PrelRules.lhs, while simplCore/ConFold.lhs has gone.
      
      * Appending of constant strings now works, using fold/build fusion, plus
        the rewrite rule
      	unpack "foo" c (unpack "baz" c n)  =  unpack "foobaz" c n
        Implemented in PrelRules.lhs
      
      * The CCall primop is tidied up quite a bit.  There is now a data type CCall,
        defined in PrimOp, that packages up the info needed for a particular CCall.
        There is a new Id for each new ccall, with an big "occurrence name"
      	{__ccall "foo" gc Int# -> Int#}
        In interface files, this is parsed as a single Id, which is what it is, really.
      
      Miscellaneous
      ~~~~~~~~~~~~~
      * There were numerous places where the host compiler's
        minInt/maxInt was being used as the target machine's minInt/maxInt.
        I nuked all of these; everything is localised to inIntRange and inWordRange,
        in Literal.lhs
      
      * Desugaring record updates was broken: it didn't generate correct matches when
        used withe records with fancy unboxing etc.  It now uses matchWrapper.
      
      * Significant tidying up in codeGen/SMRep.lhs
      
      * Add __word, __word64, __int64 terminals to signal the obvious types
        in interface files.  Add the ability to print word values in hex into
        C code.
      
      * PrimOp.lhs is no longer part of a loop.  Remove PrimOp.hi-boot*
      
      
      Types
      ~~~~~
      * isProductTyCon no longer returns False for recursive products, nor
        for unboxed products; you have to test for these separately.
        There's no reason not to do CPR for recursive product types, for example.
        Ditto splitProductType_maybe.
      
      Simplification
      ~~~~~~~~~~~~~~~
      * New -fno-case-of-case flag for the simplifier.  We use this in the first run
        of the simplifier, where it helps to stop messing up expressions that
        the (subsequent) full laziness pass would otherwise find float out.
        It's much more effective than previous half-baked hacks in inlining.
      
        Actually, it turned out that there were three places in Simplify.lhs that
        needed to know use this flag.
      
      * Make the float-in pass push duplicatable bindings into the branches of
        a case expression, in the hope that we never have to allocate them.
        (see FloatIn.sepBindsByDropPoint)
      
      * Arrange that top-level bottoming Ids get a NOINLINE pragma
        This reduced gratuitous inlining of error messages.
        But arrange that such things still get w/w'd.
      
      * Arrange that a strict argument position is regarded as an 'interesting'
        context, so that if we see
      	foldr k z (g x)
        then we'll be inclined to inline g; this can expose a build.
      
      * There was a missing case in CoreUtils.exprEtaExpandArity that meant
        we were missing some obvious cases for eta expansion
        Also improve the code when handling applications.
      
      * Make record selectors (identifiable by their IdFlavour) into "cheap" operations.
      	  [The change is a 2-liner in CoreUtils.exprIsCheap]
        This means that record selection may be inlined into function bodies, which
        greatly improves the arities of overloaded functions.
      
      * Make a cleaner job of inlining "lone variables".  There was some distributed
        cunning, but I've centralised it all now in SimplUtils.analyseCont, which
        analyses the context of a call to decide whether it is "interesting".
      
      * Don't specialise very small functions in Specialise.specDefn
        It's better to inline it.  Rather like the worker/wrapper case.
      
      * Be just a little more aggressive when floating out of let rhss.
        See comments with Simplify.wantToExpose
        A small change with an occasional big effect.
      
      * Make the inline-size computation think that
      	case x of I# x -> ...
        is *free*.
      
      
      CPR analysis
      ~~~~~~~~~~~~
      * Fix what was essentially a bug in CPR analysis.  Consider
      
      	letrec f x = let g y = let ... in f e1
      		     in
      		     if ... then (a,b) else g x
      
        g has the CPR property if f does; so when generating the final annotated
        RHS for f, we must use an envt in which f is bound to its final abstract
        value.  This wasn't happening.  Instead, f was given the CPR tag but g
        wasn't; but of course the w/w pass gives rotten results in that case!!
        (Because f's CPR-ness relied on g's.)
      
        On they way I tidied up the code in CprAnalyse.  It's quite a bit shorter.
      
        The fact that some data constructors return a constructed product shows
        up in their CPR info (MkId.mkDataConId) not in CprAnalyse.lhs
      
      
      
      Strictness analysis and worker/wrapper
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * BIG THING: pass in the demand to StrictAnal.saExpr.  This affects situations
        like
      	f (let x = e1 in (x,x))
        where f turns out to have strictness u(SS), say.  In this case we can
        mark x as demanded, and use a case expression for it.
      
        The situation before is that we didn't "know" that there is the u(SS)
        demand on the argument, so we simply computed that the body of the let
        expression is lazy in x, and marked x as lazily-demanded.  Then even after
        f was w/w'd we got
      
      	let x = e1 in case (x,x) of (a,b) -> $wf a b
      
        and hence
      
      	let x = e1 in $wf a b
      
        I found a much more complicated situation in spectral/sphere/Main.shade,
        which improved quite a bit with this change.
      
      * Moved the StrictnessInfo type from IdInfo to Demand.  It's the logical
        place for it, and helps avoid module loops
      
      * Do worker/wrapper for coerces even if the arity is zero.  Thus:
      	stdout = coerce Handle (..blurg..)
        ==>
      	wibble = (...blurg...)
      	stdout = coerce Handle wibble
        This is good because I found places where we were saying
      	case coerce t stdout of { MVar a ->
      	...
      	case coerce t stdout of { MVar b ->
      	...
        and the redundant case wasn't getting eliminated because of the coerce.
      111cee3f
  23. 15 Feb, 2000 1 commit
    • panne's avatar
      [project @ 2000-02-15 22:18:16 by panne] · 06619533
      panne authored
      First steps towards DEPRECATED before Rosebank (12yrs) takes its toll.
      Nothing very functional yet, but at least hsc can be compiled and it
      still compiles the Prelude.
      
      Parsing the pragma turned out to be a little bit more complicated than
      expected, here the comment from Parser.y:
      
         The place for module deprecation is really too restrictive, but if it
         was allowed at its natural place just before 'module', we get an ugly
         s/r conflict with the second alternative. Another solution would be the
         introduction of a new pragma DEPRECATED_MODULE, but this is not very nice,
         either, and DEPRECATED is only expected to be used by people who really
         know what they are doing. :-)
      
      Net result: Module deprecation is allowed exactly behind the module's
      name and nowhere else. I probably have to think a little bit more
      about this some day...
      06619533
  24. 17 Sep, 1999 1 commit
  25. 18 May, 1999 1 commit
  26. 02 Mar, 1999 1 commit
  27. 04 Feb, 1999 1 commit
    • simonpj's avatar
      [project @ 1999-02-04 13:45:24 by simonpj] · 937b23b9
      simonpj authored
      a) Fix black hole bug when doing -dshow-rn-trace
         (Involved reorganising where fixity exports are dealt with
          in RnNames/RnIfaces.)
      
      b) Arrange to apply Lint to imported unfoldings when -dcore-lint
      
      c) Add -fwarn-type-defaults to report use of the defaulting rules for types
      
      d) Make it so that f (error "help) --> error "help", if f is strict
         (Changes in Simplify.lhs.)
      937b23b9