1. 13 Aug, 2004 1 commit
  2. 27 Apr, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-04-27 12:47:13 by simonpj] · 74e0bdb6
      simonpj authored
      ----------------------------------------
           1. Make primOpIsCheap do something sensible
           2. Make the state hack work better
           ----------------------------------------
      
      1.  In March 2001, we changed primOpIsCheap to
      	primOpIsCheap op = False
      thereby making *no* primops seem cheap.  But this killed eta
      expansion on case (x ==# y) of True -> \s -> ...
      which is bad.  In particular a loop like
        doLoop n = loop 0
          where
            loop i | i == n    = return ()
                   | otherwise = bar i >> loop (i+1)
      allocated a closure every time round because it didn't eta expand.
      
      The problem that made us set primOpIsCheap to False was
      		let x = a +# b *# c in x +# x
      where we don't want to inline x. But primopIsCheap doesn't control
      that (it's exprIsDupable that does) so the problem doesn't occur
      even if primOpIsCheap sometimes says 'True'.  I think that perhaps
      something changed since March 2001.
      
      
      2.  Consider this
      	case x of
      	  True  -> \(s:RealWorld) -> e
      	  False -> foo
      where foo has arity 1.  If we are using the "state hack" we want to
      eta expand here.  This commit fixes arityType in the Var case (for foo)
      to take account of foo's type.
      
      Also add -fno-state-hack to the static flags, to allow the state hack to
      be switched off.
      74e0bdb6
  3. 02 Apr, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-04-02 13:34:42 by simonpj] · 52276d81
      simonpj authored
      Add a flag -fno-state-hack, which switches off the "state hack".
      
      It's claims that every function over realWorldStatePrimTy is a
      one-shot function.  This is pretty true in practice, and makes a big
      difference.  For example, consider
      	a `thenST` \ r -> ...E...
      The early full laziness pass, if it doesn't know that r is one-shot
      will pull out E (let's say it doesn't mention r) to give
      	let lvl = E in a `thenST` \ r -> ...lvl...
      When `thenST` gets inlined, we end up with
      	let lvl = E in \s -> case a s of (r, s') -> ...lvl...
      and we don't re-inline E.
      52276d81
  4. 05 Jan, 2004 1 commit
  5. 30 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-30 16:29:17 by simonpj] · f714e6b6
      simonpj authored
      ----------------------------
              Re-do kind inference (again)
      	----------------------------
      
         [WARNING: interface file binary representation has
         (as usual) changed slightly; recompile your libraries!]
      
      Inspired by the lambda-cube, for some time GHC has used
      	type Kind = Type
      That is, kinds were represented by the same data type as types.
      
      But GHC also supports unboxed types and unboxed tuples, and these
      complicate the kind system by requiring a sub-kind relationship.
      Notably, an unboxed tuple is acceptable as the *result* of a
      function but not as an *argument*.  So we have the following setup:
      
      		 ?
      		/ \
      	       /   \
      	      ??   (#)
      	     /  \
                  *   #
      
      where	*    [LiftedTypeKind]   means a lifted type
      	#    [UnliftedTypeKind] means an unlifted type
      	(#)  [UbxTupleKind]     means unboxed tuple
      	??   [ArgTypeKind]      is the lub of *,#
      	?    [OpenTypeKind]	means any type at all
      
      In particular:
      
        error :: forall a:?. String -> a
        (->)  :: ?? -> ? -> *
        (\(x::t) -> ...)	Here t::?? (i.e. not unboxed tuple)
      
      All this has beome rather difficult to accommodate with Kind=Type, so this
      commit splits the two.
      
        * Kind is a distinct type, defined in types/Kind.lhs
      
        * IfaceType.IfaceKind disappears: we just re-use Kind.Kind
      
        * TcUnify.unifyKind is a distinct unifier for kinds
      
        * TyCon no longer needs KindCon and SuperKindCon variants
      
        * TcUnify.zapExpectedType takes an expected Kind now, so that
          in TcPat.tcMonoPatBndr we can express that the bound variable
          must have an argTypeKind (??).
      
      The big change is really that kind inference is much more systematic and
      well behaved.  In particular, a kind variable can unify only with a
      "simple kind", which is built from * and (->).  This deals neatly
      with awkward questions about how we can combine sub-kinding with type
      inference.
      
      Lots of small consequential changes, especially to the kind-checking
      plumbing in TcTyClsDecls.  (We played a bit fast and loose before, and
      now we have to be more honest, in particular about how kind inference
      works for type synonyms.  They can have kinds like (* -> #), so
      
      This cures two long-standing SourceForge bugs
      
      * 753777 (tcfail115.hs), which used erroneously to pass,
        but crashed in the code generator
            type T a = Int -> (# Int, Int #)
            f :: T a -> T a
            f t = \x -> case t x of r -> r
      
      * 753780 (tc167.hs), which used erroneously to fail
            f :: (->) Int# Int#
      
      
      Still, the result is not entirely satisfactory.  In particular
      
      * The error message from tcfail115 is pretty obscure
      
      * SourceForge bug 807249 (Instance match failure on openTypeKind)
        is not fixed.  Alas.
      f714e6b6
  6. 13 Oct, 2003 1 commit
  7. 09 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-09 11:58:39 by simonpj] · 98688c6e
      simonpj authored
      -------------------------
      		GHC heart/lung transplant
      		-------------------------
      
      This major commit changes the way that GHC deals with importing
      types and functions defined in other modules, during renaming and
      typechecking.  On the way I've changed or cleaned up numerous other
      things, including many that I probably fail to mention here.
      
      Major benefit: GHC should suck in many fewer interface files when
      compiling (esp with -O).  (You can see this with -ddump-rn-stats.)
      
      It's also some 1500 lines of code shorter than before.
      
      **	So expect bugs!  I can do a 3-stage bootstrap, and run
      **	the test suite, but you may be doing stuff I havn't tested.
      ** 	Don't update if you are relying on a working HEAD.
      
      
      In particular, (a) External Core and (b) GHCi are very little tested.
      
      	But please, please DO test this version!
      
      
      	------------------------
      		Big things
      	------------------------
      
      Interface files, version control, and importing declarations
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * There is a totally new data type for stuff that lives in interface files:
      	Original names			IfaceType.IfaceExtName
      	Types				IfaceType.IfaceType
      	Declarations (type,class,id)	IfaceSyn.IfaceDecl
      	Unfoldings			IfaceSyn.IfaceExpr
        (Previously we used HsSyn for type/class decls, and UfExpr for unfoldings.)
        The new data types are in iface/IfaceType and iface/IfaceSyn.  They are
        all instances of Binary, so they can be written into interface files.
        Previous engronkulation concering the binary instance of RdrName has
        gone away -- RdrName is not an instance of Binary any more.  Nor does
        Binary.lhs need to know about the ``current module'' which it used to,
        which made it specialised to GHC.
      
        A good feature of this is that the type checker for source code doesn't
        need to worry about the possibility that we might be typechecking interface
        file stuff.  Nor does it need to do renaming; we can typecheck direct from
        IfaceSyn, saving a whole pass (module TcIface)
      
      * Stuff from interface files is sucked in *lazily*, rather than being eagerly
        sucked in by the renamer. Instead, we use unsafeInterleaveIO to capture
        a thunk for the unfolding of an imported function (say).  If that unfolding
        is every pulled on, TcIface will scramble over the unfolding, which may
        in turn pull in the interface files of things mentioned in the unfolding.
      
        The External Package State is held in a mutable variable so that it
        can be side-effected by this lazy-sucking-in process (which may happen
        way later, e.g. when the simplifier runs).   In effect, the EPS is a kind
        of lazy memo table, filled in as we suck things in.  Or you could think
        of it as a global symbol table, populated on demand.
      
      * This lazy sucking is very cool, but it can lead to truly awful bugs. The
        intent is that updates to the symbol table happen atomically, but very bad
        things happen if you read the variable for the table, and then force a
        thunk which updates the table.  Updates can get lost that way. I regret
        this subtlety.
      
        One example of the way it showed up is that the top level of TidyPgm
        (which updates the global name cache) to be much more disciplined about
        those updates, since TidyPgm may itself force thunks which allocate new
        names.
      
      * Version numbering in interface files has changed completely, fixing
        one major bug with ghc --make.  Previously, the version of A.f changed
        only if A.f's type and unfolding was textually different.  That missed
        changes to things that A.f's unfolding mentions; which was fixed by
        eagerly sucking in all of those things, and listing them in the module's
        usage list.  But that didn't work with --make, because they might have
        been already sucked in.
      
        Now, A.f's version changes if anything reachable from A.f (via interface
        files) changes.  A module with unchanged source code needs recompiling
        only if the versions of any of its free variables changes. [This isn't
        quite right for dictionary functions and rules, which aren't mentioned
        explicitly in the source.  There are extensive comments in module MkIface,
        where all version-handling stuff is done.]
      
      * We don't need equality on HsDecls any more (because they aren't used in
        interface files).  Instead we have a specialised equality for IfaceSyn
        (eqIfDecl etc), which uses IfaceEq instead of Bool as its result type.
        See notes in IfaceSyn.
      
      * The horrid bit of the renamer that tried to predict what instance decls
        would be needed has gone entirely.  Instead, the type checker simply
        sucks in whatever instance decls it needs, when it needs them.  Easy!
      
        Similarly, no need for 'implicitModuleFVs' and 'implicitTemplateHaskellFVs'
        etc.  Hooray!
      
      
      Types and type checking
      ~~~~~~~~~~~~~~~~~~~~~~~
      * Kind-checking of types is far far tidier (new module TcHsTypes replaces
        the badly-named TcMonoType).  Strangely, this was one of my
        original goals, because the kind check for types is the Right Place to
        do type splicing, but it just didn't fit there before.
      
      * There's a new representation for newtypes in TypeRep.lhs.  Previously
        they were represented using "SourceTypes" which was a funny compromise.
        Now they have their own constructor in the Type datatype.  SourceType
        has turned back into PredType, which is what it used to be.
      
      * Instance decl overlap checking done lazily.  Consider
      	instance C Int b
      	instance C a Int
        These were rejected before as overlapping, because when seeking
        (C Int Int) one couldn't tell which to use.  But there's no problem when
        seeking (C Bool Int); it can only be the second.
      
        So instead of checking for overlap when adding a new instance declaration,
        we check for overlap when looking up an Inst.  If we find more than one
        matching instance, we see if any of the candidates dominates the others
        (in the sense of being a substitution instance of all the others);
        and only if not do we report an error.
      
      
      
      	------------------------
      	     Medium things
      	------------------------
      
      * The TcRn monad is generalised a bit further.  It's now based on utils/IOEnv.lhs,
        the IO monad with an environment.  The desugarer uses the monad too,
        so that anything it needs can get faulted in nicely.
      
      * Reduce the number of wired-in things; in particular Word and Integer
        are no longer wired in.  The latter required HsLit.HsInteger to get a
        Type argument.  The 'derivable type classes' data types (:+:, :*: etc)
        are not wired in any more either (see stuff about derivable type classes
        below).
      
      * The PersistentComilerState is now held in a mutable variable
        in the HscEnv.  Previously (a) it was passed to and then returned by
        many top-level functions, which was painful; (b) it was invariably
        accompanied by the HscEnv.  This change tidies up top-level plumbing
        without changing anything important.
      
      * Derivable type classes are treated much more like 'deriving' clauses.
        Previously, the Ids for the to/from functions lived inside the TyCon,
        but now the TyCon simply records their existence (with a simple boolean).
        Anyone who wants to use them must look them up in the environment.
      
        This in turn makes it easy to generate the to/from functions (done
        in types/Generics) using HsSyn (like TcGenDeriv for ordinary derivings)
        instead of CoreSyn, which in turn means that (a) we don't have to figure
        out all the type arguments etc; and (b) it'll be type-checked for us.
        Generally, the task of generating the code has become easier, which is
        good for Manuel, who wants to make it more sophisticated.
      
      * A Name now says what its "parent" is. For example, the parent of a data
        constructor is its type constructor; the parent of a class op is its
        class.  This relationship corresponds exactly to the Avail data type;
        there may be other places we can exploit it.  (I made the change so that
        version comparison in interface files would be a bit easier; but in
        fact it tided up other things here and there (see calls to
        Name.nameParent).  For example, the declaration pool, of declararations
        read from interface files, but not yet used, is now keyed only by the 'main'
        name of the declaration, not the subordinate names.
      
      * New types OccEnv and OccSet, with the usual operations.
        OccNames can be efficiently compared, because they have uniques, thanks
        to the hashing implementation of FastStrings.
      
      * The GlobalRdrEnv is now keyed by OccName rather than RdrName.  Not only
        does this halve the size of the env (because we don't need both qualified
        and unqualified versions in the env), but it's also more efficient because
        we can use a UniqFM instead of a FiniteMap.
      
        Consequential changes to Provenance, which has moved to RdrName.
      
      * External Core remains a bit of a hack, as it was before, done with a mixture
        of HsDecls (so that recursiveness and argument variance is still inferred),
        and IfaceExprs (for value declarations).  It's not thoroughly tested.
      
      
      	------------------------
      	     Minor things
      	------------------------
      
      * DataCon fields dcWorkId, dcWrapId combined into a single field
        dcIds, that is explicit about whether the data con is a newtype or not.
        MkId.mkDataConWorkId and mkDataConWrapId are similarly combined into
        MkId.mkDataConIds
      
      * Choosing the boxing strategy is done for *source* type decls only, and
        hence is now in TcTyDecls, not DataCon.
      
      * WiredIn names are distinguished by their n_sort field, not by their location,
        which was rather strange
      
      * Define Maybes.mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
        and use it here and there
      
      * Much better pretty-printing of interface files (--show-iface)
      
      Many, many other small things.
      
      
      	------------------------
      	     File changes
      	------------------------
      * New iface/ subdirectory
      * Much of RnEnv has moved to iface/IfaceEnv
      * MkIface and BinIface have moved from main/ to iface/
      * types/Variance has been absorbed into typecheck/TcTyDecls
      * RnHiFiles and RnIfaces have vanished entirely.  Their
        work is done by iface/LoadIface
      * hsSyn/HsCore has gone, replaced by iface/IfaceSyn
      * typecheck/TcIfaceSig has gone, replaced by iface/TcIface
      * typecheck/TcMonoType has been renamed to typecheck/TcHsType
      * basicTypes/Var.hi-boot and basicTypes/Generics.hi-boot have gone altogether
      98688c6e
  8. 24 Mar, 2003 1 commit
    • simonmar's avatar
      [project @ 2003-03-24 11:23:20 by simonmar] · 82387309
      simonmar authored
      #ifdef some more code that belongs to the old strictness analyser.
      
      It turns out we were still compiling the Demand and SaLib modules,
      which aren't required unless OLD_STRICTNESS is on (do we still need
      OLD_STRICTNESS?).
      82387309
  9. 20 Mar, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-03-20 12:20:06 by simonpj] · f6c8cfd4
      simonpj authored
      ----------------------------------
            Fix a long-standing egregious CorePrep bug
      	----------------------------------
      
      	**** Merge to Stable branch ****
      
      CorePrep was eta-reducing
      
      	\x -> (# a,x #)
      to
      	(#,#) a
      
      which is utterly wrong.  Easily fixed though.
      f6c8cfd4
  10. 03 Mar, 2003 1 commit
    • simonmar's avatar
      [project @ 2003-03-03 12:43:31 by simonmar] · 19108ede
      simonmar authored
      A round of space-leak fixing.
      
        - re-instate zapping of the PersistentCompilerState at various
          points during the compilation cycle in HscMain.  This affects
          one-shot compilation only, since in this mode the information
          collected in the PCS is not required after creating the final
          interface file.
      
        - Unravel the recursive dependency between MkIface and
          CoreTidy/CoreToStg.  Previously the CafInfo for each binding was
          calculated by CoreToStg, and fed back into the IdInfo of the Ids
          generated by CoreTidy (an earlier pass).  MkIface then took this
          IdInfo and the bindings from CoreTidy to generate the interface;
          but it couldn't do this until *after* CoreToStg, because the CafInfo
          hadn't been calculated yet.  The result was that the CoreTidy
          output lived until after CoreToStg, and at the same time as the
          CorePrep and STG syntax, which is wasted space, not to mention
          the complexity and general ugliness in HscMain.
      
          So now we calculate CafInfo directly in CoreTidy.  The downside is
          that we have to predict what CorePrep is going to do to the
          bindings so we can tell what will turn into a CAF later, but it's
          no worse than before (it turned out that we were doing this
          prediction before in CoreToStg anyhow).
      
        - The typechecker lazilly typechecks unfoldings.  It turns out that
          this is a good idea from a performance perspective, but it also
          means that it must hang on to all the information it needs to
          do the typechecking.  Previously this meant holding on to the
          whole of the typechecker's environment, which includes all sorts
          of stuff which isn't necessary to typecheck unfoldings.  By paring
          down the environment captured by the lazy unfoldings, we can
          save quite a bit of space in the phases after typechecking.
      19108ede
  11. 19 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-19 15:54:05 by simonpj] · 3355c9d5
      simonpj authored
      -------------------------------------
      	 	Two minor wibbles
      	-------------------------------------
      
      
      1.  Make the generic toT/fromT Ids for "generic derived classes" into
          proper ImplicitIds, with their own GlobalIdDetails. This makes it
          easier to identify them.  (The lack of this showed up as a bug
          when I made an apparently-innocuous other change.)
      
      2.  Distinguish ClassOpIds from RecordSelIds in their GlobalIdDetails.
          They are treated differently here and there, so I made this change
          as part of (1)
      
      3.  Ensure that a declaration quotation [d| ... |] does not have a
          permanent effect on the instance environment. (A TH fix.)
      3355c9d5
  12. 12 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-12 15:01:31 by simonpj] · 42b63073
      simonpj authored
      -------------------------------------
        Big upheaval to the way that constructors are named
      	-------------------------------------
      
      This commit enshrines the new story for constructor names.  We could never
      really get External Core to work nicely before, but now it does.
      
      The story is laid out in detail in the Commentary
      	ghc/docs/comm/the-beast/data-types.html
      so I will not repeat it here.
      
      	[Manuel: the commentary isn't being updated, apparently.]
      
      However, the net effect is that in Core and in External Core, contructors look
      like constructors, and the way things are printed is all consistent.
      
      It is a fairly pervasive change (which is why it has been so long postponed),
      but I hope the question is now finally closed.
      
      All the libraries compile etc, and I've run many tests, but doubtless there will
      be some dark corners.
      42b63073
  13. 04 Feb, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-02-04 15:09:38 by simonpj] · 957bf375
      simonpj authored
      -------------------------------------
      	Remove all vestiges of usage analysis
      	-------------------------------------
      
      This commit removes a large blob of usage-analysis-related code, almost
      all of which was commented out.
      
      Sadly, it doesn't look as if Keith is going to have enough time to polish it
      up, and in any case the actual performance benefits (so far as we can measure
      them) turned out to be pretty modest (a few percent).
      
      So, with regret, I'm chopping it all out.  It's still there in the repository
      if anyone wants go hack on it.  And Tobias Gedell at Chalmers is implementing
      a different analysis, via External Core.
      957bf375
  14. 19 Nov, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-11-19 14:16:43 by simonmar] · de7a4a03
      simonmar authored
      - Fix a bug in eta-expansion of an application; it probably never bit
        us in practice.
      
      - Change the behaviour of State#-lambdas: previously a State# lambda
        was considered to be one-shot for the purposes of inlining and
        eta-expansion.  Both can lead to unbounded extra work, but inlining
        is more likely to kill us, and eta-expansion is the case we mostly
        care about (getting the State# lambda to the outside of the function
        is often very important).  So now we only consider a State# lambda to be
        one-shot in eta expansion, not for inlining.
      de7a4a03
  15. 29 Jul, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-07-29 10:50:43 by simonmar] · 5bca7237
      simonmar authored
      Type variables created by the typechecker didn't have the correct
      NameSpace: they were in the Var namespace rather than the TyVar
      namespace, which can lead to strange warnings about quantified type
      variables being not mentioned in the type when DEBUG is on.
      
      Name:
      	- added mkSystemNameEncoded for use when the string
      	  is already encoded (saves re-encoding the string every
      	  time)
      
      	- added mkSystemTvNameEncoded for making a type variable
      	  name, as above
      
      Var:
      	- use mkSystemTvNameEncoded when making type variables
      
      Id:
      	- add mkSysLocalUnencoded for the (rare) case when
      	  the string needs encoding
      
      TcMType:
      	- use mkSystemTvNameEncoded rather than mkSystemName for
      	  making type variables
      
      SetLevels:
      	- use mkSysLocalUnencoded since the names generated here
      	  need encoding.
      5bca7237
  16. 14 Jun, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-06-14 14:03:25 by simonpj] · 990dd09b
      simonpj authored
      ---------------------------------------
      	Utterly expunge the tyGenInfo field of
      			an IdInfo
      	---------------------------------------
      
      tyGenInfo was a relic of a previous version of Keith's usage
      analyser.  It's just dead code, so I've nuked it.
      990dd09b
  17. 04 Apr, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-04-04 13:15:18 by simonpj] · c44e1c41
      simonpj authored
      ---------------------------------------
      	A glorious improvement to CPR analysis
      	---------------------------------------
      
      Working on the CPR paper, I finally figured out how to
      do a decent job of taking account of strictness analyis when doing
      CPR analysis.
      
      There are two places we do that:
      
      1.  Usually, on a letrec for a *thunk* we discard any CPR info from
      the RHS.  We can't worker/wrapper a thunk.  BUT, if the let is
      	non-recursive
      	non-top-level
      	used strictly
      we don't need to discard the CPR info, because the thunk-splitting
      transform (WorkWrap.splitThunk) works.  This idea isn't new in this
      commit.
      
      
      2. Arguments to strict functions.  Consider
      
        fac n m = if n==0 then m
      		    else fac (n-1) (m*n)
      
      Does it have the CPR property?  Apparently not, because it returns the
      accumulating parameter, m.  But the strictness analyser will
      discover that fac is strict in m, so it will be passed unboxed to
      the worker for fac.  More concretely, here is the worker/wrapper
      split that will result from strictness analysis alone:
      
        fac n m = case n of MkInt n' ->
      	    case m of MkInt m' ->
      	    facw n' m'
      
        facw n' m' = if n' ==# 0#
      	       then I# m'
      	       else facw (n' -# 1#) (m' *# n')
      
      Now facw clearly does have the CPR property!  We can take advantage
      of this by giving a demanded lambda the CPR property.
      
      
      To make this work nicely, I've made NewDemandInfo into Maybe Demand
      rather than simply Demand, so that we can tell when we are on the
      first iteration.  Lots of comments about this in Note [CPR-AND-STRICTNESS].
      
      I don't know how much all this buys us, but it is simple and elegant.
      c44e1c41
  18. 18 Mar, 2002 1 commit
  19. 15 Mar, 2002 1 commit
  20. 14 Mar, 2002 1 commit
    • simonpj's avatar
      [project @ 2002-03-14 15:27:15 by simonpj] · 1553c778
      simonpj authored
      ------------------------
      	Change
      		GlobalName --> ExternalName
      		LocalName  ->  InternalName
      	------------------------
      
      For a long time there's been terminological confusion between
      
      	GlobalName vs LocalName	 (property of a Name)
      	GlobalId vs LocalId	 (property of an Id)
      
      I've now changed the terminology for Name to be
      
      	ExternalName vs InternalName
      
      I've also added quite a bit of documentation in the Commentary.
      1553c778
  21. 04 Mar, 2002 1 commit
    • simonmar's avatar
      [project @ 2002-03-04 17:01:26 by simonmar] · 0171936c
      simonmar authored
      Binary Interface Files - stage 1
      --------------------------------
      
      This commit changes the default interface file format from text to
      binary, in order to improve compilation performace.
      
      To view an interface file, use 'ghc --show-iface Foo.hi'.
      
      utils/Binary.hs is the basic Binary I/O library, based on the nhc98
      binary I/O library but much stripped-down and working in terms of
      bytes rather than bits, and with some special features for GHC: it
      remembers which Module is being emitted to avoid dumping too many
      qualified names, and it keeps track of a "dictionary" of FastStrings
      so that we don't dump the same FastString more than once into the
      binary file.  I'll make a generic version of this for the libraries at
      some point.
      
      main/BinIface.hs contains most of the Binary instances.  Some
      instances are in the same module as the data type (RdrName, Name,
      OccName in particular).  Most instances were generated using a
      modified version of DrIFT, which I'll commit later.  However, editing
      them by hand isn't hard (certainly easier than modifying
      ParseIface.y).
      
      The first thing in a binary interface is the interface version, so
      nice error messages will be generated if the binary format changes and
      you still have old interfaces lying around.  The version also now
      includes the "way" as an extra sanity check.
      
      Other changes
      -------------
      
      I don't like the way FastStrings contain both hashed strings (with
      O(1) comparison) and literal C strings (with O(n) comparison).  So as
      a first step to separating these I made serveral "literal" type
      strings into hashed strings.  SLIT() still generates a literal, and
      now FSLIT() generates a hashed string.  With DEBUG on, you'll get a
      warning if you try to compare any SLIT()s with anything, and the
      compiler will fall over if you try to dump any literal C strings into
      an interface file (usually indicating a use of SLIT() which should be
      FSLIT()).
      
      mkSysLocal no longer re-encodes its FastString argument each time it
      is called.
      
      I also fixed the -pgm options so that the argument can now optionally
      be separted from the option.
      
      Bugfix: PrelNames declared Names for several comparison primops, eg.
      eqCharName, eqIntName etc. but these had different uniques from the
      real primop names.  I've moved these to PrimOps and defined them using
      mkPrimOpIdName instead, and deleted some for which we don't have real
      primops (Manuel: please check that things still work for you after
      this change).
      0171936c
  22. 10 Dec, 2001 1 commit
    • simonmar's avatar
      [project @ 2001-12-10 14:07:30 by simonmar] · 973539a8
      simonmar authored
      Make the inclusion of the old strictness analyser, CPR analyser, and
      the relevant IdInfo components, conditional on DEBUG.  This makes
      IdInfo smaller by three fields in a non-DEBUG compiler, and reduces
      the risk that the unused fields could harbour space leaks.
      
      Eventually these passes will go away altogether.
      973539a8
  23. 26 Nov, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-11-26 09:20:25 by simonpj] · 5e3f005d
      simonpj authored
      ----------------------
      	Implement Rank-N types
      	----------------------
      
      This commit implements the full glory of Rank-N types, using
      the Odersky/Laufer approach described in their paper
      	"Putting type annotations to work"
      
      In fact, I've had to adapt their approach to deal with the
      full glory of Haskell (including pattern matching, and the
      scoped-type-variable extension).  However, the result is:
      
      * There is no restriction to rank-2 types.  You can nest forall's
        as deep as you like in a type.  For example, you can write a type
        like
      	p :: ((forall a. Eq a => a->a) -> Int) -> Int
        This is a rank-3 type, illegal in GHC 5.02
      
      * When matching types, GHC uses the cunning Odersky/Laufer coercion
        rules.  For example, suppose we have
      	q :: (forall c. Ord c => c->c) -> Int
        Then, is this well typed?
      	x :: Int
      	x = p q
        Yes, it is, but GHC has to generate the right coercion.  Here's
        what it looks like with all the big lambdas and dictionaries put in:
      
      	x = p (\ f :: (forall a. Eq a => a->a) ->
      		 q (/\c \d::Ord c -> f c (eqFromOrd d)))
      
        where eqFromOrd selects the Eq superclass dictionary from the Ord
        dicationary:		eqFromOrd :: Ord a -> Eq a
      
      
      * You can use polymorphic types in pattern type signatures.  For
        example:
      
      	f (g :: forall a. a->a) = (g 'c', g True)
      
        (Previously, pattern type signatures had to be monotypes.)
      
      * The basic rule for using rank-N types is that you must specify
        a type signature for every binder that you want to have a type
        scheme (as opposed to a plain monotype) as its type.
      
        However, you don't need to give the type signature on the
        binder (as I did above in the defn for f).  You can give it
        in a separate type signature, thus:
      
      	f :: (forall a. a->a) -> (Char,Bool)
      	f g = (g 'c', g True)
      
        GHC will push the external type signature inwards, and use
        that information to decorate the binders as it comes across them.
        I don't have a *precise* specification of this process, but I
        think it is obvious enough in practice.
      
      * In a type synonym you can use rank-N types too.  For example,
        you can write
      
      	type IdFun = forall a. a->a
      
      	f :: IdFun -> (Char,Bool)
      	f g = (g 'c', g True)
      
        As always, type synonyms must always occur saturated; GHC
        expands them before it does anything else.  (Still, GHC goes
        to some trouble to keep them unexpanded in error message.)
      
      
      The main plan is as before.  The main typechecker for expressions,
      tcExpr, takes an "expected type" as its argument.  This greatly
      improves error messages.  The new feature is that when this
      "expected type" (going down) meets an "actual type" (coming up)
      we use the new subsumption function
      	TcUnify.tcSub
      which checks that the actual type can be coerced into the
      expected type (and produces a coercion function to demonstrate).
      
      The main new chunk of code is TcUnify.tcSub.  The unifier itself
      is unchanged, but it has moved from TcMType into TcUnify.  Also
      checkSigTyVars has moved from TcMonoType into TcUnify.
      Result: the new module, TcUnify, contains all stuff relevant
      to subsumption and unification.
      
      Unfortunately, there is now an inevitable loop between TcUnify
      and TcSimplify, but that's just too bad (a simple TcUnify.hi-boot
      file).
      
      
      All of this doesn't come entirely for free.  Here's the typechecker
      line count (INCLUDING comments)
      	Before	16,551
      	After	17,116
      5e3f005d
  24. 19 Nov, 2001 2 commits
    • simonpj's avatar
      [project @ 2001-11-19 16:34:12 by simonpj] · 53ce311e
      simonpj authored
      Tidy up imports
      53ce311e
    • simonpj's avatar
      [project @ 2001-11-19 14:23:52 by simonpj] · d8af6b8c
      simonpj authored
      --------------------------------------
      	Yet another cut at the DmdAnal domains
      	--------------------------------------
      
      This version of the domain for demand analysis was developed
      in discussion with Peter Sestoft, so I think it might at last
      be more or less right!
      
      Our idea is mentally to separate
      	strictness analysis
      from
      	absence and boxity analysis
      
      Then we combine them back into a single domain.  The latter
      is all you see in the compiler (the Demand type, as before)
      but we understand it better now.
      d8af6b8c
  25. 18 Oct, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-10-18 16:29:12 by simonpj] · 685e04e4
      simonpj authored
      ----------------------------------------------
      	The CoreTidy/CorePrep/CoreToStg saga continues
      	[actually, this commit mostly completes the job]
      	----------------------------------------------
      
      			DO NOT MERGE!
      
      * CorePrep injects implicit bindings, not the type checker,
        nor CgConTbls.   (This way, all the code generators see
        them, so no need to fiddle with the byte code generator.)
      
        As a result, all bindings in the module are for LocalIds,
        at least until CoreTidy.   This is a Big Win.
      
        Hence remove nasty isImplicitId test in update_bndr in
        SimplCore and DmdAnal
      
      * hasNoBinding is no longer true of a dataConId (worker).
        There's an implicit curried binding for it.
      
      * Remove yukky test in exprIsTrivial that did not regard
        a hasNoBinding Id as trivial; similarly in SimplUtils.tryEtaReduce
      
      * In CoreTidy, get the names to avoid from the type env.
        That way it includes implicit bindings too.
      
      * CoreTidy set the Arity of a top-level Id permanently;
        it's up to the rest of the compiler to respect it.
        Notably, CorePrep uses etaExpand to make the manifest arity
        match the claimed arity.
      
      * As a result, nuke CgArity, so that CgInfo now contains only
        CafInfo.  The CafInfo is knot-tied as before.
      
      
      Other things
      
      * In Simplify.simplLazyBind, be a bit keener to float bindings
        out if it's a top-level binding.
      685e04e4
  26. 15 Oct, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-10-15 15:06:01 by simonpj] · 713b32a5
      simonpj authored
      --------------------------
      	Tidy up arity propagation
      	--------------------------
      
      Due to excessive complexity, correct arity information was getting
      lost on the way to interface files.  As a result, a function that had
      CPR info __S SLm (say), was getting arity 0, and this confused the (old)
      CPR analyser ("lub of function and HasCPR").
      
      I hope this fixes the above error (which showed up somewhere in
      compiling Edison), but I'm going to commit it right now anyway.
      Meanwhile I'll recompile Edison too.
      
      
      Details
      ~~~~~~~
      Digging out the rather obscure cause made me tidy up the CgInfo stuff.
      The story is now
      
      * The CgInfo field of an Id gets attached to the Id *only* in
        the TypeEnv of the ModuleDetails, during CoreTidy.
      
        This ModuleDetails stuff is used
      	a) to generate the interface file
      	b) to import into other modules in GHCi
      
      * No CgInfo field is in the CoreBindings which are passed
        downsteam to CorePrep and thence CodeGen.  Quite right too...
        it's the downstream stuff that *generates* the CgInfo.
      
      * But the Arity field *is* now passed on through CoreTidy
        (like strictness info) since it is usefully used by CorePrep.
      
      * On the way I simplified the ArityInfo field of an IdInfo
        to simply
      		Arity
        instead of
      		Maybe Arity
      713b32a5
  27. 26 Sep, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-09-26 15:12:33 by simonpj] · e0d750be
      simonpj authored
      ------------------
      		Simon's big commit
      		------------------
      
      This commit, which I don't think I can sensibly do piecemeal, consists
      of the things I've been doing recently, mainly directed at making
      Manuel, George, and Marcin happier with RULES.
      
      
      Reogranise the simplifier
      ~~~~~~~~~~~~~~~~~~~~~~~~~
      1. The simplifier's environment is now an explicit parameter.  This
      makes it a bit easier to figure out where it is going.
      
      2. Constructor arguments can now be arbitrary expressions, except
      when the application is the RHS of a let(rec).  This makes it much
      easier to match rules like
      
      	RULES
      	    "foo"  f (h x, g y) = f' x y
      
      In the simplifier, it's Simplify.mkAtomicArgs that ANF-ises a
      constructor application where necessary.  In the occurrence analyser,
      there's a new piece of context info (OccEncl) to say whether a
      constructor app is in a place where it should be in ANF.  (Unless
      it knows this it'll give occurrence info which will inline the
      argument back into the constructor app.)
      
      3. I'm experimenting with doing the "float-past big lambda" transformation
      in the full laziness pass, rather than mixed in with the simplifier (was
      tryRhsTyLam).
      
      4.  Arrange that
      	case (coerce (S,T) (x,y)) of ...
      will simplify.  Previous it didn't.
      A local change to CoreUtils.exprIsConApp_maybe.
      
      5. Do a better job in CoreUtils.exprEtaExpandArity when there's an
      error function in one branch.
      
      
      Phase numbers, RULES, and INLINE pragmas
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      1.  Phase numbers decrease from N towards zero (instead of increasing).
      This makes it easier to add new earlier phases, which is what users want
      to do.
      
      2.  RULES get their own phase number, N, and are disabled in phases before N.
      
      e.g. 	{-# RULES "foo" [2] forall x y.  f (x,y) = f' x y #-}
      
      Note the [2], which says "only active in phase 2 and later".
      
      3.  INLINE and NOINLINE pragmas have a phase number to.  This is now treated
      in just the same way as the phase number on RULE; that is, the Id is not inlined
      in phases earlier than N.  In phase N and later the Id *may* be inlined, and
      here is where INLINE and NOINLINE differ: INLNE makes the RHS look small, so
      as soon as it *may* be inlined it probably *will* be inlined.
      
      The syntax of the phase number on an INLINE/NOINLINE pragma has changed to be
      like the RULES case (i.e. in square brackets).  This should also make sure
      you examine all such phase numbers; many will need to change now the numbering
      is reversed.
      
      Inlining Ids is no longer affected at all by whether the Id appears on the
      LHS of a rule.  Now it's up to the programmer to put a suitable INLINE/NOINLINE
      pragma to stop it being inlined too early.
      
      
      Implementation notes:
      
      *  A new data type, BasicTypes.Activation says when a rule or inline pragma
      is active.   Functions isAlwaysActive, isNeverActive, isActive, do the
      obvious thing (all in BasicTypes).
      
      * Slight change in the SimplifierSwitch data type, which led to a lot of
      simplifier-specific code moving from CmdLineOpts to SimplMonad; a Good Thing.
      
      * The InlinePragma in the IdInfo of an Id is now simply an Activation saying
      when the Id can be inlined.  (It used to be a rather bizarre pair of a
      Bool and a (Maybe Phase), so this is much much easier to understand.)
      
      * The simplifier has a "mode" environment switch, replacing the old
      black list.  Unfortunately the data type decl has to be in
      CmdLineOpts, because it's an argument to the CoreDoSimplify switch
      
          data SimplifierMode = SimplGently | SimplPhase Int
      
      Here "gently" means "no rules, no inlining".   All the crucial
      inlining decisions are now collected together in SimplMonad
      (preInlineUnconditionally, postInlineUnconditionally, activeInline,
      activeRule).
      
      
      Specialisation
      ~~~~~~~~~~~~~~
      1.  Only dictionary *functions* are made INLINE, not dictionaries that
      have no parameters.  (This inline-dictionary-function thing is Marcin's
      idea and I'm still not sure whether it's a good idea.  But it's definitely
      a Bad Idea when there are no arguments.)
      
      2.  Be prepared to specialise an INLINE function: an easy fix in
      Specialise.lhs
      
      But there is still a problem, which is that the INLINE wins
      at the call site, so we don't use the specialised version anyway.
      I'm still unsure whether it makes sense to SPECIALISE something
      you want to INLINE.
      
      
      
      
      
      Random smaller things
      ~~~~~~~~~~~~~~~~~~~~~~
      
      * builtinRules (there was only one, but may be more) in PrelRules are now
        incorporated.   They were being ignored before...
      
      * OrdList.foldOL -->  OrdList.foldrOL, OrdList.foldlOL
      
      * Some tidying up of the tidyOpenTyVar, tidyTyVar functions.  I've
        forgotten exactly what!
      e0d750be
  28. 20 Sep, 2001 1 commit
  29. 07 Sep, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-09-07 12:44:30 by simonpj] · 991a868b
      simonpj authored
      ----------------------------------------
      	Make dict funs and default methods
      	into LocalIds only at their binding site
      	----------------------------------------
              [part of 3 related commits]
      
      There's a long comment about this with MkId.mkDefaultMethodId,
      which I reproduce below.
      
      While I was at it, I renamed setIdNoDiscard to setIdLocalExported.
      Which is hardly an improvement, I'm afraid.  This renaming touches
      	Var.lhs, Id.lhs, SimplCore.lhs
      in a trivial way.
      
      	---------------------
      
      Dict funs and default methods are *not* ImplicitIds.  Their definition
      involves user-written code, so we can't figure out their strictness etc
      based on fixed info, as we can for constructors and record selectors (say).
      
      We build them as GlobalIds, but when in the module where they are
      bound, we turn the Id at the *binding site* into an exported LocalId.
      This ensures that they are taken to account by free-variable finding
      and dependency analysis (e.g. CoreFVs.exprFreeVars).   The simplifier
      will propagate the LocalId to all occurrence sites.
      
      Why shouldn't they be bound as GlobalIds?  Because, in particular, if
      they are globals, the specialiser floats dict uses above their defns,
      which prevents good simplifications happening.  Also the strictness
      analyser treats a occurrence of a GlobalId as imported and assumes it
      contains strictness in its IdInfo, which isn't true if the thing is
      bound in the same module as the occurrence.
      
      It's OK for dfuns to be LocalIds, because we form the instance-env to
      pass on to the next module (md_insts) in CoreTidy, afer tidying
      and globalising the top-level Ids.
      
      BUT make sure they are *exported* LocalIds (setIdLocalExported) so
      that they aren't discarded by the occurrence analyser.
      991a868b
  30. 20 Aug, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-08-20 16:50:13 by simonpj] · 0c190d9e
      simonpj authored
      -------------------------------------
      	Make NOINLINE zap the strictness info
      	-------------------------------------
      
      Make a NOINLINE pragma zap strictness information.
      Reasons given in the WorkWrap comment:
      
      	-- Furthermore, zap the strictess info in the Id.  Why?  Because
      	-- the NOINLINE says "don't expose any of the inner workings at the call
      	-- site" and the strictness is certainly an inner working.
      	--
      	-- More concretely, the demand analyser discovers the following strictness
      	-- for unsafePerformIO:  C(U(AV))
      	-- But then consider
      	--	unsafePerformIO (\s -> let r = f x in
      	--			       case writeIORef v r s of (# s1, _ #) ->
      	--			       (# s1, r #)
      	-- The strictness analyser will find that the binding for r is strict,
      	-- (becuase of uPIO's strictness sig), and so it'll evaluate it before
      	-- doing the writeIORef.  This actually makes tests/lib/should_run/memo002
      	-- get a deadlock!
      	--
      	-- Solution: don't expose the strictness of unsafePerformIO.
      
      This fixes the memo002 deadlock.
      0c190d9e
  31. 23 Jul, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-07-23 10:54:46 by simonpj] · f6cd95ff
      simonpj authored
      ---------------------------------
      	Switch to the new demand analyser
      	---------------------------------
      
      This commit makes the new demand analyser the main beast,
      with the old strictness analyser as a backup.  When
      DEBUG is on, the old strictness analyser is run too, and the
      results compared.
      
      WARNING: this isn't thorougly tested yet, so expect glitches.
      Delay updating for a few days if the HEAD is mission critical
      for you.
      
      But do try it out.  I'm away for 2.5 weeks from Thursday, so
      it would be good to shake out any glaring bugs before then.
      f6cd95ff
  32. 20 Jul, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-07-20 15:22:21 by simonpj] · 0fa26afe
      simonpj authored
      -----------------------
      	Get rid of ArityAtLeast
      	-----------------------
      
      Now that we have CgInfo, with the exact code-generator arity
      for the value, we don't need the distinction between ArityAtLeast
      and ArityExactly in the ArityInfo field of an IdInfo.
      
      This commit makes
      
      	type ArityInfo = Maybe Arity
      
      and propagates this change consistently through the compiler.
      0fa26afe
  33. 25 Jun, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-06-25 08:09:57 by simonpj] · d069cec2
      simonpj authored
      ----------------
      	Squash newtypes
      	----------------
      
      This commit squashes newtypes and their coerces, from the typechecker
      onwards.  The original idea was that the coerces would not get in the
      way of optimising transformations, but despite much effort they continue
      to do so.   There's no very good reason to retain newtype information
      beyond the typechecker, so now we don't.
      
      Main points:
      
      * The post-typechecker suite of Type-manipulating functions is in
      types/Type.lhs, as before.   But now there's a new suite in types/TcType.lhs.
      The difference is that in the former, newtype are transparent, while in
      the latter they are opaque.  The typechecker should only import TcType,
      not Type.
      
      * The operations in TcType are all non-monadic, and most of them start with
      "tc" (e.g. tcSplitTyConApp).  All the monadic operations (used exclusively
      by the typechecker) are in a new module, typecheck/TcMType.lhs
      
      * I've grouped newtypes with predicate types, thus:
      	data Type = TyVarTy Tyvar | ....
      		  | SourceTy SourceType
      
      	data SourceType = NType TyCon [Type]
      			| ClassP Class [Type]
      			| IParam Type
      
      [SourceType was called PredType.]  This is a little wierd in some ways,
      because NTypes can't occur in qualified types.   However, the idea is that
      a SourceType is a type that is opaque to the type checker, but transparent
      to the rest of the compiler, and newtypes fit that as do implicit parameters
      and dictionaries.
      
      * Recursive newtypes still retain their coreces, exactly as before. If
      they were transparent we'd get a recursive type, and that would make
      various bits of the compiler diverge (e.g. things which do type comparison).
      
      * I've removed types/Unify.lhs (non-monadic type unifier and matcher),
      merging it into TcType.
      
      Ditto typecheck/TcUnify.lhs (monadic unifier), merging it into TcMType.
      d069cec2
  34. 22 May, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-05-22 13:43:14 by simonpj] · f16228e4
      simonpj authored
      -------------------------------------------
      	Towards generalising 'foreign' declarations
      	-------------------------------------------
      
      This is a first step towards generalising 'foreign' declarations to
      handle langauges other than C.  Quite a lot of files are touched,
      but nothing has really changed.  Everything should work exactly as
      before.
      
      	But please be on your guard for ccall-related bugs.
      
      Main things
      
      Basic data types: ForeignCall.lhs
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * Remove absCSyn/CallConv.lhs
      
      * Add prelude/ForeignCall.lhs.  This defines the ForeignCall
        type and its variants
      
      * Define ForeignCall.Safety to say whether a call is unsafe
        or not (was just a boolean).  Lots of consequential chuffing.
      
      * Remove all CCall stuff from PrimOp, and put it in ForeignCall
      
      
      Take CCallOp out of the PrimOp type (where it was always a glitch)
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * Add IdInfo.FCallId variant to the type IdInfo.GlobalIdDetails,
      	along with predicates Id.isFCallId, Id.isFCallId_maybe
      
      * Add StgSyn.StgOp, to sum PrimOp with FCallOp, because it
        *is* useful to sum them together in Stg and AbsC land.  If
        nothing else, it minimises changes.
      
      
      Also generally rename "CCall" stuff to "FCall" where it's generic
      to all foreign calls.
      f16228e4
  35. 18 May, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-05-18 08:46:18 by simonpj] · b4775e5e
      simonpj authored
      -----------------------------
      	Get unbox-strict-fields right
      	-----------------------------
      
      The problem was that when a library was compiled *without* -funbox-strict-fields,
      and the main program was compiled *with* that flag, we were wrongly treating
      the fields of imported data types as unboxed.
      
      To fix this I added an extra constructor to StrictnessMark to express whether
      the "!" annotation came from an interface file (don't fiddle) or a source
      file (decide whether to unbox).
      
      On the way I tided things up:
      
      * StrictnessMark moves to Demand.lhs, and doesn't have the extra DataCon
        fields that kept it in DataCon before.
      
      * HsDecls.BangType has one constructor, not three, with a StrictnessMark field.
      
      * DataCon keeps track of its strictness signature (dcRepStrictness), but not
        its "user strict marks" (which were never used)
      
      * All the functions, like getUniquesDs, that used to take an Int saying how
        many uniques to allocate, now return an infinite list. This saves arguments
        and hassle.  But it involved touching quite a few files.
      
      * rebuildConArgs takes a list of Uniques to use as its unique supply.  This
        means I could combine DsUtils.rebuildConArgs with MkId.rebuildConArgs
        (hooray; the main point of the previous change)
      
      
      I also tidied up one or two error messages
      b4775e5e
  36. 14 May, 2001 1 commit
  37. 13 Mar, 2001 1 commit
    • simonmar's avatar
      [project @ 2001-03-13 12:50:29 by simonmar] · 10cbc75d
      simonmar authored
      Some rearrangements that Simon & I have been working on recently:
      
          - CoreSat is now CorePrep, and is a general "prepare-for-code-
            generation" pass.  It does cloning, saturation of constructors &
            primops, A-normal form, and a couple of other minor fiddlings.
      
          - CoreTidy no longer does cloning, and minor fiddlings.  It doesn't
            need the unique supply any more, so that's removed.
      
          - CoreToStg now collects CafInfo and the list of CafRefs for each
            binding.  The SRT pass is much simpler now.
      
          - IdInfo now has a CgInfo field for "code generator info".  It currently
            contains arity (the actual code gen arity which affects the calling
            convention as opposed to the ArityInfo which is a measure of how
            many arguments the Id can be applied to before it does any work), and
            CafInfo.
      
            Previously we overloaded the ArityInfo field to contain both
            codegen arity and simplifier arity.  Things are cleaner now.
      
          - CgInfo is collected by CoreToStg, and passed back into CoreTidy in
            a loop.  The compiler will complain rather than going into a black
            hole if the CgInfo is pulled on too early.
      
          - Worker info in an interface file now comes with arity info attached.
            Previously the main arity info was overloaded for this purpose, but
            it lead to a few hacks in the compiler, this tidies things up somewhat.
      
      Bottom line: we removed several fragilities, and tidied up a number of
      things.  Code size should be smaller, but we'll see...
      10cbc75d
  38. 08 Mar, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-03-08 12:07:38 by simonpj] · 51a571c0
      simonpj authored
      --------------------
      	A major hygiene pass
      	--------------------
      
      1. The main change here is to
      
      	Move what was the "IdFlavour" out of IdInfo,
      	and into the varDetails field of a Var
      
         It was a mess before, because the flavour was a permanent attribute
         of an Id, whereas the rest of the IdInfo was ephemeral.  It's
         all much tidier now.
      
         Main places to look:
      
      	   Var.lhs	Defn of VarDetails
      	   IdInfo.lhs	Defn of GlobalIdDetails
      
         The main remaining infelicity is that SpecPragmaIds are right down
         in Var.lhs, which seems unduly built-in for such an ephemeral thing.
         But that is no worse than before.
      
      
      2. Tidy up the HscMain story a little.  Move mkModDetails from MkIface
         into CoreTidy (where it belongs more nicely)
      
         This was partly forced by (1) above, because I didn't want to make
         DictFun Ids into a separate kind of Id (which is how it was before).
         Not having them separate means we have to keep a list of them right
         through, rather than pull them out of the bindings at the end.
      
      3. Add NameEnv as a separate module (to join NameSet).
      
      4. Remove unnecessary {-# SOURCE #-} imports from FieldLabel.
      51a571c0
  39. 01 Mar, 2001 1 commit
    • simonpj's avatar
      [project @ 2001-03-01 17:10:06 by simonpj] · 09518039
      simonpj authored
      Improve IdInfo substitution
      
      To get rules to work nicely, we need to make rules for recursive functions
      active in the RHS of the very recursive function itself.  This can be
      done nicely: the change is to move the calls to simplIdInfo in Simplify
      to an earlier place.
      
      The second thing is that when doing simple expression substitution
      in a rule (which we do during simplification for rules attached to an Id)
      we were zapping the occurrence info carefully pinned on the rule binders
      when the rule was put into the Id's rules.  This in turn meant that
      the simplifer ran more iterations than necessary when rules were fired.
      (Andrew Tolmach discovered this.)
      
      So I tidied up the interface to Subst a little.  The relevant functions
      that have changed are
      	simplBndr, simplBndrs, simplLetId, simplIdInfo,
      	substAndCloneId, substAndCloneIds, substAndCloneRecIds,
      
      There are consequential changes in other modules, but it compiles
      at least the whole standard libraries happily, and the codegen tests,
      so I'm reasonably confident in it.  But watch out for new strange
      happenings.
      09518039