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In Core, the Note constructor has been replaced by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)

1 files changed, 14 insertions, 17 deletions

diff --git a/compiler/codeGen/CgClosure.lhs b/compiler/codeGen/CgClosure.lhs
index bccadb5a5d..32190a3c9c 100644
--- a/compiler/codeGen/CgClosure.lhs
+++ b/compiler/codeGen/CgClosure.lhs
@@ -108,7 +108,7 @@ cgStdRhsClosure
 	-> [StgArg]		-- payload
 	-> FCode (Id, CgIdInfo)
 
-cgStdRhsClosure bndr cc _bndr_info _fvs args body lf_info payload 
+cgStdRhsClosure bndr _cc _bndr_info _fvs _args _body lf_info payload
   = do	-- AHA!  A STANDARD-FORM THUNK
   {	-- LAY OUT THE OBJECT
     amodes <- getArgAmodes payload
@@ -122,10 +122,10 @@ cgStdRhsClosure bndr cc _bndr_info _fvs args body lf_info payload
 				     NoC_SRT	-- No SRT for a std-form closure
 				     descr
 		
-  ; (use_cc, blame_cc) <- chooseDynCostCentres cc args body
+--  ; (use_cc, blame_cc) <- chooseDynCostCentres cc args body
 
 	-- BUILD THE OBJECT
-  ; heap_offset <- allocDynClosure closure_info use_cc blame_cc amodes_w_offsets
+  ; heap_offset <- allocDynClosure closure_info curCCS curCCS amodes_w_offsets
 
 	-- RETURN
   ; returnFC (bndr, heapIdInfo bndr heap_offset lf_info) }
@@ -197,9 +197,9 @@ cgRhsClosure bndr cc bndr_info fvs upd_flag args body = do
   ; let
 	to_amode (info, offset) = do { amode <- idInfoToAmode info
 				     ; return (amode, offset) }
-  ; (use_cc, blame_cc) <- chooseDynCostCentres cc args body
+--  ; (use_cc, blame_cc) <- chooseDynCostCentres cc args body
   ; amodes_w_offsets <- mapFCs to_amode bind_details
-  ; heap_offset <- allocDynClosure closure_info use_cc blame_cc amodes_w_offsets
+  ; heap_offset <- allocDynClosure closure_info curCCS curCCS amodes_w_offsets
 
 	-- RETURN
   ; returnFC (bndr, heapIdInfo bndr heap_offset lf_info) }
@@ -239,16 +239,15 @@ So it should set up an update frame (if it is shared).
 NB: Thunks cannot have a primitive type!
 
 \begin{code}
-closureCodeBody _binder_info cl_info cc [{- No args i.e. thunk -}] body = do
+closureCodeBody _binder_info cl_info _cc [{- No args i.e. thunk -}] body = do
   { body_absC <- getCgStmts $ do
 	{ tickyEnterThunk cl_info
 	; ldvEnterClosure cl_info  -- NB: Node always points when profiling
 	; thunkWrapper cl_info $ do
 		-- We only enter cc after setting up update so
 		-- that cc of enclosing scope will be recorded
-		-- in update frame CAF/DICT functions will be
-		-- subsumed by this enclosing cc
-	    { enterCostCentre cl_info cc body
+                -- in the update frame
+            { enterCostCentreThunk (CmmReg nodeReg)
 	    ; cgExpr body }
 	}
     
@@ -307,16 +306,14 @@ mkFunEntryCode cl_info cc reg_args stk_args sp_top reg_save_code body = do
   ; bindArgsToStack stk_args
   ; setRealAndVirtualSp sp_top
 
-	-- Enter the cost-centre, if required
-	-- ToDo: It's not clear why this is outside the funWrapper,
-	--	 but the tickyEnterFun is inside. Perhaps we can put
-	--	 them together?
-  ; enterCostCentre cl_info cc body
-
-	-- Do the business
+        -- Do the business
   ; funWrapper cl_info reg_args reg_save_code $ do
 	{ tickyEnterFun cl_info
-	; cgExpr body }
+        ; enterCostCentreFun cc $
+              CmmMachOp mo_wordSub [ CmmReg nodeReg
+                                   , CmmLit (mkIntCLit (funTag cl_info)) ]
+
+        ; cgExpr body }
   }
 \end{code}