Rollback INLINE patches

rolling back:

Fri Dec  5 16:54:00 GMT 2008  simonpj@microsoft.com
  * Completely new treatment of INLINE pragmas (big patch)
  
  This is a major patch, which changes the way INLINE pragmas work.
  Although lots of files are touched, the net is only +21 lines of
  code -- and I bet that most of those are comments!
  
  HEADS UP: interface file format has changed, so you'll need to
  recompile everything.
  
  There is not much effect on overall performance for nofib, 
  probably because those programs don't make heavy use of INLINE pragmas.
  
          Program           Size    Allocs   Runtime   Elapsed
              Min         -11.3%     -6.9%     -9.2%     -8.2%
              Max          -0.1%     +4.6%     +7.5%     +8.9%
   Geometric Mean          -2.2%     -0.2%     -1.0%     -0.8%
  
  (The +4.6% for on allocs is cichelli; see other patch relating to
  -fpass-case-bndr-to-join-points.)
  
  The old INLINE system
  ~~~~~~~~~~~~~~~~~~~~~
  The old system worked like this. A function with an INLINE pragam
  got a right-hand side which looked like
       f = __inline_me__ (\xy. e)
  The __inline_me__ part was an InlineNote, and was treated specially
  in various ways.  Notably, the simplifier didn't inline inside an
  __inline_me__ note.  
  
  As a result, the code for f itself was pretty crappy. That matters
  if you say (map f xs), because then you execute the code for f,
  rather than inlining a copy at the call site.
  
  The new story: InlineRules
  ~~~~~~~~~~~~~~~~~~~~~~~~~~
  The new system removes the InlineMe Note altogether.  Instead there
  is a new constructor InlineRule in CoreSyn.Unfolding.  This is a 
  bit like a RULE, in that it remembers the template to be inlined inside
  the InlineRule.  No simplification or inlining is done on an InlineRule,
  just like RULEs.  
  
  An Id can have an InlineRule *or* a CoreUnfolding (since these are two
  constructors from Unfolding). The simplifier treats them differently:
  
    - An InlineRule is has the substitution applied (like RULES) but 
      is otherwise left undisturbed.
  
    - A CoreUnfolding is updated with the new RHS of the definition,
      on each iteration of the simplifier.
  
  An InlineRule fires regardless of size, but *only* when the function
  is applied to enough arguments.  The "arity" of the rule is specified
  (by the programmer) as the number of args on the LHS of the "=".  So
  it makes a difference whether you say
    	{-# INLINE f #-}
  	f x = \y -> e     or     f x y = e
  This is one of the big new features that InlineRule gives us, and it
  is one that Roman really wanted.
  
  In contrast, a CoreUnfolding can fire when it is applied to fewer
  args than than the function has lambdas, provided the result is small
  enough.
  
  
  Consequential stuff
  ~~~~~~~~~~~~~~~~~~~
  * A 'wrapper' no longer has a WrapperInfo in the IdInfo.  Instead,
    the InlineRule has a field identifying wrappers.
  
  * Of course, IfaceSyn and interface serialisation changes appropriately.
  
  * Making implication constraints inline nicely was a bit fiddly. In
    the end I added a var_inline field to HsBInd.VarBind, which is why
    this patch affects the type checker slightly
  
  * I made some changes to the way in which eta expansion happens in
    CorePrep, mainly to ensure that *arguments* that become let-bound
    are also eta-expanded.  I'm still not too happy with the clarity
    and robustness fo the result.
  
  * We now complain if the programmer gives an INLINE pragma for
    a recursive function (prevsiously we just ignored it).  Reason for
    change: we don't want an InlineRule on a LoopBreaker, because then
    we'd have to check for loop-breaker-hood at occurrence sites (which
    isn't currenlty done).  Some tests need changing as a result.
  
  This patch has been in my tree for quite a while, so there are
  probably some other minor changes.
  

    M ./compiler/basicTypes/Id.lhs -11
    M ./compiler/basicTypes/IdInfo.lhs -82
    M ./compiler/basicTypes/MkId.lhs -2 +2
    M ./compiler/coreSyn/CoreFVs.lhs -2 +25
    M ./compiler/coreSyn/CoreLint.lhs -5 +1
    M ./compiler/coreSyn/CorePrep.lhs -59 +53
    M ./compiler/coreSyn/CoreSubst.lhs -22 +31
    M ./compiler/coreSyn/CoreSyn.lhs -66 +92
    M ./compiler/coreSyn/CoreUnfold.lhs -112 +112
    M ./compiler/coreSyn/CoreUtils.lhs -185 +184
    M ./compiler/coreSyn/MkExternalCore.lhs -1
    M ./compiler/coreSyn/PprCore.lhs -4 +40
    M ./compiler/deSugar/DsBinds.lhs -70 +118
    M ./compiler/deSugar/DsForeign.lhs -2 +4
    M ./compiler/deSugar/DsMeta.hs -4 +3
    M ./compiler/hsSyn/HsBinds.lhs -3 +3
    M ./compiler/hsSyn/HsUtils.lhs -2 +7
    M ./compiler/iface/BinIface.hs -11 +25
    M ./compiler/iface/IfaceSyn.lhs -13 +21
    M ./compiler/iface/MkIface.lhs -24 +19
    M ./compiler/iface/TcIface.lhs -29 +23
    M ./compiler/main/TidyPgm.lhs -55 +49
    M ./compiler/parser/ParserCore.y -5 +6
    M ./compiler/simplCore/CSE.lhs -2 +1
    M ./compiler/simplCore/FloatIn.lhs -6 +1
    M ./compiler/simplCore/FloatOut.lhs -23
    M ./compiler/simplCore/OccurAnal.lhs -36 +5
    M ./compiler/simplCore/SetLevels.lhs -59 +54
    M ./compiler/simplCore/SimplCore.lhs -48 +52
    M ./compiler/simplCore/SimplEnv.lhs -26 +22
    M ./compiler/simplCore/SimplUtils.lhs -28 +4
    M ./compiler/simplCore/Simplify.lhs -91 +109
    M ./compiler/specialise/Specialise.lhs -15 +18
    M ./compiler/stranal/WorkWrap.lhs -14 +11
    M ./compiler/stranal/WwLib.lhs -2 +2
    M ./compiler/typecheck/Inst.lhs -1 +3
    M ./compiler/typecheck/TcBinds.lhs -17 +27
    M ./compiler/typecheck/TcClassDcl.lhs -1 +2
    M ./compiler/typecheck/TcExpr.lhs -4 +6
    M ./compiler/typecheck/TcForeign.lhs -1 +1
    M ./compiler/typecheck/TcGenDeriv.lhs -14 +13
    M ./compiler/typecheck/TcHsSyn.lhs -3 +2
    M ./compiler/typecheck/TcInstDcls.lhs -5 +4
    M ./compiler/typecheck/TcRnDriver.lhs -2 +11
    M ./compiler/typecheck/TcSimplify.lhs -10 +17
    M ./compiler/vectorise/VectType.hs +7

Mon Dec  8 12:43:10 GMT 2008  simonpj@microsoft.com
  * White space only

    M ./compiler/simplCore/Simplify.lhs -2

Mon Dec  8 12:48:40 GMT 2008  simonpj@microsoft.com
  * Move simpleOptExpr from CoreUnfold to CoreSubst

    M ./compiler/coreSyn/CoreSubst.lhs -1 +87
    M ./compiler/coreSyn/CoreUnfold.lhs -72 +1

Mon Dec  8 17:30:18 GMT 2008  simonpj@microsoft.com
  * Use CoreSubst.simpleOptExpr in place of the ad-hoc simpleSubst (reduces code too)

    M ./compiler/deSugar/DsBinds.lhs -50 +16

Tue Dec  9 17:03:02 GMT 2008  simonpj@microsoft.com
  * Fix Trac #2861: bogus eta expansion
  
  Urghlhl!  I "tided up" the treatment of the "state hack" in CoreUtils, but
  missed an unexpected interaction with the way that a bottoming function
  simply swallows excess arguments.  There's a long
       Note [State hack and bottoming functions]
  to explain (which accounts for most of the new lines of code).
  

    M ./compiler/coreSyn/CoreUtils.lhs -16 +53

Mon Dec 15 10:02:21 GMT 2008  Simon Marlow <marlowsd@gmail.com>
  * Revert CorePrep part of "Completely new treatment of INLINE pragmas..."
  
  The original patch said:
  
  * I made some changes to the way in which eta expansion happens in
    CorePrep, mainly to ensure that *arguments* that become let-bound
    are also eta-expanded.  I'm still not too happy with the clarity
    and robustness fo the result.
    
  Unfortunately this change apparently broke some invariants that were
  relied on elsewhere, and in particular lead to panics when compiling
  with profiling on.
  
  Will re-investigate in the new year.

    M ./compiler/coreSyn/CorePrep.lhs -53 +58
    M ./configure.ac -1 +1

Mon Dec 15 12:28:51 GMT 2008  Simon Marlow <marlowsd@gmail.com>
  * revert accidental change to configure.ac

    M ./configure.ac -1 +1

1 files changed, 26 insertions, 22 deletions

diff --git a/compiler/simplCore/SimplEnv.lhs b/compiler/simplCore/SimplEnv.lhs
index 12b3ce56ce..a2e06a0bf7 100644
--- a/compiler/simplCore/SimplEnv.lhs
+++ b/compiler/simplCore/SimplEnv.lhs
@@ -29,7 +29,7 @@ module SimplEnv (
 
 	simplNonRecBndr, simplRecBndrs, simplLamBndr, simplLamBndrs, 
  	simplBinder, simplBinders, addBndrRules,
-	substExpr, substTy, substUnfolding,
+	substExpr, substWorker, substTy, 
 
 	-- Floats
   	Floats, emptyFloats, isEmptyFloats, addNonRec, addFloats, extendFloats,
@@ -49,7 +49,7 @@ import VarEnv
 import VarSet
 import OrdList
 import Id
-import qualified CoreSubst	( Subst, mkSubst, substExpr, substSpec, substUnfolding )
+import qualified CoreSubst	( Subst, mkSubst, substExpr, substSpec, substWorker )
 import qualified Type		( substTy, substTyVarBndr )
 import Type hiding		( substTy, substTyVarBndr )
 import Coercion
@@ -528,7 +528,7 @@ simplLamBndr env bndr
   where
     old_unf = idUnfolding bndr
     (env1, id1) = substIdBndr env bndr
-    id2  = id1 `setIdUnfolding` substUnfolding env False old_unf
+    id2  = id1 `setIdUnfolding` substUnfolding env old_unf
     env2 = modifyInScope env1 id2
 
 ---------------
@@ -660,6 +660,29 @@ addBndrRules env in_id out_id
     old_rules = idSpecialisation in_id
     new_rules = CoreSubst.substSpec subst out_id old_rules
     final_id  = out_id `setIdSpecialisation` new_rules
+
+------------------
+substIdType :: SimplEnv -> Id -> Id
+substIdType (SimplEnv { seInScope = in_scope,  seTvSubst = tv_env}) id
+  | isEmptyVarEnv tv_env || isEmptyVarSet (tyVarsOfType old_ty) = id
+  | otherwise	= Id.setIdType id (Type.substTy (TvSubst in_scope tv_env) old_ty)
+		-- The tyVarsOfType is cheaper than it looks
+		-- because we cache the free tyvars of the type
+		-- in a Note in the id's type itself
+  where
+    old_ty = idType id
+
+------------------
+substUnfolding :: SimplEnv -> Unfolding -> Unfolding
+substUnfolding _   NoUnfolding     	       = NoUnfolding
+substUnfolding _   (OtherCon cons) 	       = OtherCon cons
+substUnfolding env (CompulsoryUnfolding rhs)   = CompulsoryUnfolding (substExpr env rhs)
+substUnfolding env (CoreUnfolding rhs t v w g) = CoreUnfolding (substExpr env rhs) t v w g
+
+------------------
+substWorker :: SimplEnv -> WorkerInfo -> WorkerInfo
+substWorker _   NoWorker = NoWorker
+substWorker env wkr_info = CoreSubst.substWorker (mkCoreSubst env) wkr_info
 \end{code}
 
 
@@ -695,28 +718,9 @@ mkCoreSubst (SimplEnv { seInScope = in_scope, seTvSubst = tv_env, seIdSubst = id
     fiddle (DoneId v)       = Var v
     fiddle (ContEx tv id e) = CoreSubst.substExpr (mk_subst tv id) e
 
-------------------
-substIdType :: SimplEnv -> Id -> Id
-substIdType (SimplEnv { seInScope = in_scope,  seTvSubst = tv_env}) id
-  | isEmptyVarEnv tv_env || isEmptyVarSet (tyVarsOfType old_ty) = id
-  | otherwise	= Id.setIdType id (Type.substTy (TvSubst in_scope tv_env) old_ty)
-		-- The tyVarsOfType is cheaper than it looks
-		-- because we cache the free tyvars of the type
-		-- in a Note in the id's type itself
-  where
-    old_ty = idType id
-
-------------------
 substExpr :: SimplEnv -> CoreExpr -> CoreExpr
 substExpr env expr = CoreSubst.substExpr (mkCoreSubst env) expr
   -- Do *not* short-cut in the case of an empty substitution
   -- See CoreSubst: Note [Extending the Subst]
-
-substUnfolding :: SimplEnv -> Bool -> Unfolding -> Unfolding
-substUnfolding env is_top_lvl unf 
-  | InlineRule {} <- unf' = unf' { uf_is_top = is_top_lvl }
-  | otherwise             = unf'
-  where
-    unf' = CoreSubst.substUnfolding (mkCoreSubst env) unf
 \end{code}