Overhaul of infrastructure for profiling, coverage (HPC) and breakpoints

User visible changes
====================

Profilng
--------

Flags renamed (the old ones are still accepted for now):

  OLD            NEW
  ---------      ------------
  -auto-all      -fprof-auto
  -auto          -fprof-exported
  -caf-all       -fprof-cafs

New flags:

  -fprof-auto              Annotates all bindings (not just top-level
                           ones) with SCCs

  -fprof-top               Annotates just top-level bindings with SCCs

  -fprof-exported          Annotates just exported bindings with SCCs

  -fprof-no-count-entries  Do not maintain entry counts when profiling
                           (can make profiled code go faster; useful with
                           heap profiling where entry counts are not used)

Cost-centre stacks have a new semantics, which should in most cases
result in more useful and intuitive profiles.  If you find this not to
be the case, please let me know.  This is the area where I have been
experimenting most, and the current solution is probably not the
final version, however it does address all the outstanding bugs and
seems to be better than GHC 7.2.

Stack traces
------------

+RTS -xc now gives more information.  If the exception originates from
a CAF (as is common, because GHC tends to lift exceptions out to the
top-level), then the RTS walks up the stack and reports the stack in
the enclosing update frame(s).

Result: +RTS -xc is much more useful now - but you still have to
compile for profiling to get it.  I've played around a little with
adding 'head []' to GHC itself, and +RTS -xc does pinpoint the problem
quite accurately.

I plan to add more facilities for stack tracing (e.g. in GHCi) in the
future.

Coverage (HPC)
--------------

 * derived instances are now coloured yellow if they weren't used
 * likewise record field names
 * entry counts are more accurate (hpc --fun-entry-count)
 * tab width is now correct (markup was previously off in source with
   tabs)

Internal changes
================

In Core, the Note constructor has been replaced by

        Tick (Tickish b) (Expr b)

which is used to represent all the kinds of source annotation we
support: profiling SCCs, HPC ticks, and GHCi breakpoints.

Depending on the properties of the Tickish, different transformations
apply to Tick.  See CoreUtils.mkTick for details.

Tickets
=======

This commit closes the following tickets, test cases to follow:

  - Close #2552: not a bug, but the behaviour is now more intuitive
    (test is T2552)

  - Close #680 (test is T680)

  - Close #1531 (test is result001)

  - Close #949 (test is T949)

  - Close #2466: test case has bitrotted (doesn't compile against current
    version of vector-space package)

3 files changed, 18 insertions, 14 deletions

diff --git a/compiler/hsSyn/Convert.lhs b/compiler/hsSyn/Convert.lhs
index 5ece574e25..f9c275e4f3 100644
--- a/compiler/hsSyn/Convert.lhs
+++ b/compiler/hsSyn/Convert.lhs
@@ -130,7 +130,8 @@ cvtDec (TH.ValD pat body ds)
 	; ds' <- cvtLocalDecs (ptext (sLit "a where clause")) ds
 	; returnL $ Hs.ValD $
           PatBind { pat_lhs = pat', pat_rhs = GRHSs body' ds' 
-		  , pat_rhs_ty = void, bind_fvs = placeHolderNames } }
+                  , pat_rhs_ty = void, bind_fvs = placeHolderNames
+                  , pat_ticks = (Nothing,[]) } }
 
 cvtDec (TH.FunD nm cls)   
   | null cls
diff --git a/compiler/hsSyn/HsBinds.lhs b/compiler/hsSyn/HsBinds.lhs
index 31e7c29798..56d0040788 100644
--- a/compiler/hsSyn/HsBinds.lhs
+++ b/compiler/hsSyn/HsBinds.lhs
@@ -18,6 +18,7 @@ import {-# SOURCE #-} HsPat  ( LPat )
 
 import HsTypes
 import PprCore ()
+import CoreSyn
 import Coercion
 import Type
 import Name
@@ -120,7 +121,7 @@ data HsBindLR idL idR
                                 -- See Note [Bind free vars]
 
 
-        fun_tick :: Maybe (Int,[Id])   -- ^ This is the (optional) module-local tick number.
+        fun_tick :: Maybe (Tickish Id)  -- ^ Tick to put on the rhs, if any
     }
 
   | PatBind {   -- The pattern is never a simple variable;
@@ -128,7 +129,10 @@ data HsBindLR idL idR
         pat_lhs    :: LPat idL,
         pat_rhs    :: GRHSs idR,
         pat_rhs_ty :: PostTcType,       -- Type of the GRHSs
-        bind_fvs   :: NameSet           -- See Note [Bind free vars]
+        bind_fvs   :: NameSet,          -- See Note [Bind free vars]
+        pat_ticks  :: (Maybe (Tickish Id), [Maybe (Tickish Id)])
+               -- ^ Tick to put on the rhs, if any, and ticks to put on
+               -- the bound variables.
     }
 
   | VarBind {   -- Dictionary binding and suchlike
@@ -383,9 +387,12 @@ instance (OutputableBndr id) => Outputable (ABExport id) where
 pprTicks :: SDoc -> SDoc -> SDoc
 -- Print stuff about ticks only when -dppr-debug is on, to avoid
 -- them appearing in error messages (from the desugarer); see Trac # 3263
+-- Also print ticks in dumpStyle, so that -ddump-hpc actually does
+-- something useful.
 pprTicks pp_no_debug pp_when_debug
-  = getPprStyle (\ sty -> if debugStyle sty then pp_when_debug
-                                            else pp_no_debug)
+  = getPprStyle (\ sty -> if debugStyle sty || dumpStyle sty
+                             then pp_when_debug
+                             else pp_no_debug)
 \end{code}
 
 %************************************************************************
diff --git a/compiler/hsSyn/HsExpr.lhs b/compiler/hsSyn/HsExpr.lhs
index 995c66068c..31d65b47db 100644
--- a/compiler/hsSyn/HsExpr.lhs
+++ b/compiler/hsSyn/HsExpr.lhs
@@ -18,6 +18,7 @@ import HsTypes
 import HsBinds
 
 -- others:
+import CoreSyn
 import Var
 import Name
 import BasicTypes
@@ -248,8 +249,7 @@ data HsExpr id
   -- Haskell program coverage (Hpc) Support
 
   | HsTick
-     Int                                -- module-local tick number
-     [id]                               -- variables in scope
+     (Tickish id)
      (LHsExpr id)                       -- sub-expression
 
   | HsBinTick
@@ -298,6 +298,7 @@ tupArgPresent (Missing {}) = False
 
 type PendingSplice = (Name, LHsExpr Id) -- Typechecked splices, waiting to be
                                         -- pasted back in by the desugarer
+
 \end{code}
 
 Note [Parens in HsSyn]
@@ -503,14 +504,9 @@ ppr_expr (HsQuasiQuoteE qq)  = ppr qq
 ppr_expr (HsProc pat (L _ (HsCmdTop cmd _ _ _)))
   = hsep [ptext (sLit "proc"), ppr pat, ptext (sLit "->"), ppr cmd]
 
-ppr_expr (HsTick tickId vars exp)
+ppr_expr (HsTick tickish exp)
   = pprTicks (ppr exp) $
-    hcat [ptext (sLit "tick<"),
-    ppr tickId,
-    ptext (sLit ">("),
-    hsep (map pprHsVar vars),
-    ppr exp,
-    ptext (sLit ")")]
+    ppr tickish <+> ppr exp
 ppr_expr (HsBinTick tickIdTrue tickIdFalse exp)
   = pprTicks (ppr exp) $
     hcat [ptext (sLit "bintick<"),