The I# constructor is always removed when we make a unique later
anyway, so this just saves a bit of time and allocation.

Most of the other users of the fptools build system have migrated to
Cabal, and with the move to darcs we can now flatten the source tree
without losing history, so here goes.

The main change is that the ghc/ subdir is gone, and most of what it
contained is now at the top level.  The build system now makes no
pretense at being multi-project, it is just the GHC build system.

No doubt this will break many things, and there will be a period of
instability while we fix the dependencies.  A straightforward build
should work, but I haven't yet fixed binary/source distributions.
Changes to the Building Guide will follow, too.

foreign import syntax

------------------------------------
	Major increment for Template Haskell
	------------------------------------

1.  New abstract data type "Name" which appears where String used to be.
    E.g. 	data Exp = VarE Name | ...

2.  New syntax 'x and ''T, for quoting Names.  It's rather like [| x |]
    and [t| T |] respectively, except that

	a) it's non-monadic:  'x :: Name
	b) you get a Name not an Exp or Type

3.  reify is an ordinary function
	reify :: Name -> Q Info
    New data type Info which tells what TH knows about Name

4.  Local variables work properly.  So this works now (crashed before):
	f x = $( [| x |] )

5.  THSyntax is split up into three modules:

  Language.Haskell.TH		TH "clients" import this

  Language.Haskell.TH.THSyntax	data type declarations and internal stuff

  Language.Haskell.TH.THLib	Support library code (all re-exported
				by TH), including smart constructors and
				pretty printer

6.  Error reporting and recovery are in (not yet well tested)

	report :: Bool {- True <=> fatal -} -> String -> Q ()
	recover :: Q a -> Q a -> Q a

7.  Can find current module

	currentModule :: Q String


Much other cleaning up, needless to say.

Simplified my previous quick-fix-after-some-beers

Make "one of the most hammered bits in the whole compiler" (quotation
from the source code :-) compile without _ccall_

Housekeeping:

  - The main goal is to remove dependencies on hslibs for a
    bootstrapped compiler, leaving only a requirement that the
    packages base, haskell98 and readline are built in stage 1 in
    order to bootstrap.  We're almost there: Posix is still required
    for signal handling, but all other dependencies on hslibs are now
    gone.

    Uses of Addr and ByteArray/MutableByteArray array are all gone
    from the compiler.  PrimPacked defines the Ptr type for GHC 4.08
    (which didn't have it), and it defines simple BA and MBA types to
    replace uses of ByteArray and MutableByteArray respectively.

  - Clean up import lists.  HsVersions.h now defines macros for some
    modules which have moved between GHC versions.  eg. one now
    imports 'GLAEXTS' to get at unboxed types and primops in the
    compiler.

    Many import lists have been sorted as per the recommendations in
    the new style guidelines in the commentary.

I've built the compiler with GHC 4.08.2, 5.00.2, 5.02.3, 5.04 and
itself, and everything still works here.  Doubtless I've got something
wrong, though.

Comments

Never-ending story, part #2: The shifting continues...

-----------------------------
	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

Do a better job of eta expansion.

This showed up in one of Manuel's programs, where he got code like:

    $wsimpleGen
	     ww
	     (\ i :: Int ->
		  case i of wild1 { I# i# ->
		  case w of wild2 { I# e# ->
		  __coerce (ST RealWorld ())
		  (\ s# :: (State# RealWorld) ->
		       case writeIntArray# @ RealWorld mba# i# e# s#
		       of s2#1 { __DEFAULT ->
		       (# s2#1, () #)
		       })
		  }
		  })
	     s2#

The argument wasn't eta expanded, so it got right through to
the code generator as two separte lambdas.

Needless to say, I fiddled around with things in a vain attempt
to tidy them up.  Yell if anything seems to go wrong, or perfomance
drops on any programs.

Major thing: new register allocator.  Brief description follows.
Should correctly handle code with loops in, even though we don't
generate any such at the moment.  A lot of comments.  The previous
machinery for spilling is retained, as is the idea of a fast-and-easy
initial allocation attempt intended to deal with the majority of code
blocks (about 60% on x86) very cheaply.  Many comments explaining
in detail how it works :-)

The Stix inliner is now on by default.  Integer code seems to run
within about 1% of that -fvia-C.  x86 fp code is significantly worse,
up to about 30% slower, depending on the amount of fp activity.

Minor thing: lazyfication of the top-level NCG plumbing, so that the
NCG doesn't require any greater residency than compiling to C, just a
bit more time.  Created lazyThenUs and lazyMapUs for this purpose.

The new allocator is somewhat, although not catastophically, slower
than the old one.  Fixing of the long-standing NCG space leak more
than makes up for it; overall hsc run-time is down about 5%, due to
significantly reduced GC time.

--------------------------------------------------------------------

Instructions are numbered sequentially, starting at zero.

A flow edge (FE) is a pair of insn numbers (MkFE Int Int) denoting
a possible flow of control from the first insn to the second.

The input to the register allocator is a list of instructions, which
mention Regs.  A Reg can be a RealReg -- a real machine reg -- or a
VirtualReg, which carries a unique.  After allocation, all the
VirtualReg references will have been converted into RealRegs, and
possibly some spill code will have been inserted.

The heart of the register allocator works in four phases.

1.  (find_flow_edges) Calculate all the FEs for the code list.
    Return them not as a [FE], but implicitly, as a pair of
    Array Int [Int], being the successor and predecessor maps
    for instructions.

2.  (calc_liveness) Returns a FiniteMap FE RegSet.  For each
    FE, indicates the set of registers live on that FE.  Note
    that the set includes both RealRegs and VirtualRegs.  The
    former appear because the code could mention fixed register
    usages, and we need to take them into account from the start.

3.  (calc_live_range_sets) Invert the above mapping, giving a
    FiniteMap Reg FeSet, indicating, for each virtual and real
    reg mentioned in the code, which FEs it is live on.

4.  (calc_vreg_to_rreg_mapping) For virtual reg, try and find
    an allocatable real register for it.  Each real register has
    a "current commitment", indicating the set of FEs it is
    currently live on.  A virtual reg v can be assigned to
    real reg r iff v's live-fe-set does not intersect with r's
    current commitment fe-set.  If the assignment is made,
    v's live-fe-set is union'd into r's current commitment fe-set.
    There is also the minor restriction that v and r must be of
    the same register class (integer or floating).

    Once this mapping is established, we simply apply it to the
    input insns, and that's it.

    If no suitable real register can be found, the vreg is mapped
    to itself, and we deem allocation to have failed.  The partially
    allocated code is returned.  The higher echelons of the allocator
    (doGeneralAlloc and runRegAlloc) then cooperate to insert spill
    code and re-run allocation, until a successful allocation is found.

(this is number 4 of 9 commits to be applied together)

  The major purpose of this commit is to introduce usage information
  and usage analysis into the compiler, per the paper _Once Upon a
  Polymorphic Type_ (Keith Wansbrough and Simon Peyton Jones, POPL'99,
  and Glasgow TR-1998-19).

  Usage information has been added to types, in the form of a new kind
  of NoteTy: (UsgNote UsageAnn(UsOnce|UsMany|UsVar UVar)).  Usages
  print as __o (once), __m (many, usually omitted), or (not in
  interface files) __uvxxxx.  Usage annotations should only appear at
  certain places in a type (see the paper).  The `default' annotation
  is __m, and so an omitted annotation implies __m.  Utility functions
  for handling usage annotations are provided in Type.

  If the compiler is built with -DUSMANY (a flag intended for use in
  debugging by KSW only), __m are *required* and may not be omitted.

  The major constraint is that type arguments (eg to mkAppTy) must be
  unannotated on top.  To maintain this invariant, many functions
  required the insertion of Type.unUsgTy (removing annot from top of a
  type) or UsageSPUtils.unannotTy (removing all annotations from a
  type).  A function returning usage-annotated types for primops has
  been added to PrimOp.

  A new kind of Note, (TermUsg UsageAnn), has been added to annotate
  Terms.  This note is *not* printed in interface files, and for the
  present does not escape the internals of the usage inference engine.

zh --> Zh

Zh --> zh

Another big commit from Simon.  Actually, the last one
didn't all go into the main trunk; because of a CVS glitch it
ended up in the wrong branch.

So this commit includes:

* Scoped type variables
* Warnings for unused variables should work now (they didn't before)
* Simplifier improvements:
	- Much better treatment of strict arguments
	- Better treatment of bottoming Ids
	- No need for w/w split for fns that are merely strict
	- Fewer iterations needed, I hope
* Less gratuitous renaming in interface files and abs C
* OccName is a separate module, and is an abstract data type

I think the whole Prelude and Exts libraries compile correctly.
Something isn't quite right about typechecking existentials though.

Move 4.01 onto the main trunk.

- Fixes for bootstrapping with 3.01.
  - Use 'official' extension interfaces rather than internal prelude
    modules (such as ArrBase) where possible.
  - Remove some cruft.
  - Delete some unused imports found by '-fwarn-unused-imports'.

The Great Multi-Parameter Type Classes Merge.

Notes from Simon (abridged):

* Multi-parameter type classes are fully implemented.
* Error messages from the type checker should be noticeably improved
* Warnings for unused bindings (-fwarn-unused-names)
* many other minor bug fixes.

Internally there are the following changes

* Removal of Haskell 1.2 compatibility.
* Dramatic clean-up of the PprStyle stuff.
* The type Type has been substantially changed.
* The dictionary for each class is represented by a new
  data type for that purpose, rather than by a tuple.

fix to have it compile with 2.09 (and later)

last minute 2.04 fixes

2.04 changes

Major update to more-or-less 2.02

Cross module worker-wrappers

SLPJ new renamer and lots more

Bulk of final changes for 2.01

SLPJ 1.3 changes through 96/06/25

SLPJ changes through 960604

SLPJ 1.3 changes through 960501

SLPJ 1.3 changes to 960430

SLPJ 1.3 changes through 960425

Sansom 1.3 changes through 960407

Add SLPJ/WDP 1.3 changes through 960404

Final compiler stuff before Sansom renamer 960321

simonpj/sansom/partain/dnt 1.3 compiler stuff through 96/03/18