Separate CPR analysis from the Demand analyserwip/sep-cpr

The reasons for that can be found in the wiki:
https://gitlab.haskell.org/ghc/ghc/wikis/nested-cpr/split-off-cpr

We now run CPR after demand analysis (except for after the final demand
analysis run just before code gen). CPR got its own dump flags
(`-ddump-cpr-anal`, `-ddump-cpr-signatures`), but not its own flag to
activate/deactivate. It will run with `-fstrictness`/`-fworker-wrapper`.

As explained on the wiki page, this step is necessary for a sane Nested
CPR analysis. And it has quite positive impact on compiler performance:

Metric Decrease:
    T9233
    T9675
    T9961
    T15263

6 files changed, 29 insertions, 18 deletions

diff --git a/compiler/simplCore/CallArity.hs b/compiler/simplCore/CallArity.hs
index 75c55c698c..d3709ac82a 100644
--- a/compiler/simplCore/CallArity.hs
+++ b/compiler/simplCore/CallArity.hs
@@ -701,7 +701,7 @@ trimArity v a = minimum [a, max_arity_by_type, max_arity_by_strsig]
   where
     max_arity_by_type = length (typeArity (idType v))
     max_arity_by_strsig
-        | isBotRes result_info = length demands
+        | isBotDiv result_info = length demands
         | otherwise = a
 
     (demands, result_info) = splitStrictSig (idStrictness v)
diff --git a/compiler/simplCore/CoreMonad.hs b/compiler/simplCore/CoreMonad.hs
index 672b56e64f..24567cb1c3 100644
--- a/compiler/simplCore/CoreMonad.hs
+++ b/compiler/simplCore/CoreMonad.hs
@@ -107,7 +107,8 @@ data CoreToDo           -- These are diff core-to-core passes,
   | CoreDoStaticArgs
   | CoreDoCallArity
   | CoreDoExitify
-  | CoreDoStrictness
+  | CoreDoDemand
+  | CoreDoCpr
   | CoreDoWorkerWrapper
   | CoreDoSpecialising
   | CoreDoSpecConstr
@@ -134,7 +135,8 @@ instance Outputable CoreToDo where
   ppr CoreDoStaticArgs         = text "Static argument"
   ppr CoreDoCallArity          = text "Called arity analysis"
   ppr CoreDoExitify            = text "Exitification transformation"
-  ppr CoreDoStrictness         = text "Demand analysis"
+  ppr CoreDoDemand             = text "Demand analysis"
+  ppr CoreDoCpr                = text "Constructed Product Result analysis"
   ppr CoreDoWorkerWrapper      = text "Worker Wrapper binds"
   ppr CoreDoSpecialising       = text "Specialise"
   ppr CoreDoSpecConstr         = text "SpecConstr"
diff --git a/compiler/simplCore/SetLevels.hs b/compiler/simplCore/SetLevels.hs
index 7cf0b9d524..8f70df9d79 100644
--- a/compiler/simplCore/SetLevels.hs
+++ b/compiler/simplCore/SetLevels.hs
@@ -88,6 +88,7 @@ import UniqDSet         ( getUniqDSet )
 import VarEnv
 import Literal          ( litIsTrivial )
 import Demand           ( StrictSig, Demand, isStrictDmd, splitStrictSig, increaseStrictSigArity )
+import Cpr              ( mkCprSig, botCpr )
 import Name             ( getOccName, mkSystemVarName )
 import OccName          ( occNameString )
 import Type             ( Type, mkLamTypes, splitTyConApp_maybe, tyCoVarsOfType
@@ -983,6 +984,7 @@ annotateBotStr id n_extra mb_str
       Nothing           -> id
       Just (arity, sig) -> id `setIdArity`      (arity + n_extra)
                               `setIdStrictness` (increaseStrictSigArity n_extra sig)
+                              `setIdCprInfo`    mkCprSig (arity + n_extra) botCpr
 
 notWorthFloating :: CoreExpr -> [Var] -> Bool
 -- Returns True if the expression would be replaced by
diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs
index 026631df37..4c7e509f4c 100644
--- a/compiler/simplCore/SimplCore.hs
+++ b/compiler/simplCore/SimplCore.hs
@@ -45,6 +45,7 @@ import SAT              ( doStaticArgs )
 import Specialise       ( specProgram)
 import SpecConstr       ( specConstrProgram)
 import DmdAnal          ( dmdAnalProgram )
+import CprAnal          ( cprAnalProgram )
 import CallArity        ( callArityAnalProgram )
 import Exitify          ( exitifyProgram )
 import WorkWrap         ( wwTopBinds )
@@ -141,7 +142,7 @@ getCoreToDo dflags
     maybe_rule_check phase = runMaybe rule_check (CoreDoRuleCheck phase)
 
     maybe_strictness_before phase
-      = runWhen (phase `elem` strictnessBefore dflags) CoreDoStrictness
+      = runWhen (phase `elem` strictnessBefore dflags) CoreDoDemand
 
     base_mode = SimplMode { sm_phase      = panic "base_mode"
                           , sm_names      = []
@@ -175,14 +176,12 @@ getCoreToDo dflags
                           -- Don't do case-of-case transformations.
                           -- This makes full laziness work better
 
-    strictness_pass = if ww_on
-                       then [CoreDoStrictness,CoreDoWorkerWrapper]
-                       else [CoreDoStrictness]
+    dmd_cpr_ww = if ww_on then [CoreDoDemand,CoreDoCpr,CoreDoWorkerWrapper]
+                          else [CoreDoDemand,CoreDoCpr]
 
 
-    -- New demand analyser
     demand_analyser = (CoreDoPasses (
-                           strictness_pass ++
+                           dmd_cpr_ww ++
                            [simpl_phase 0 ["post-worker-wrapper"] max_iter]
                            ))
 
@@ -332,7 +331,7 @@ getCoreToDo dflags
         simpl_phase 0 ["final"] max_iter,
 
         runWhen late_dmd_anal $ CoreDoPasses (
-            strictness_pass ++
+            dmd_cpr_ww ++
             [simpl_phase 0 ["post-late-ww"] max_iter]
           ),
 
@@ -341,7 +340,7 @@ getCoreToDo dflags
         -- has run at all. See Note [Final Demand Analyser run] in DmdAnal
         -- It is EXTREMELY IMPORTANT to run this pass, otherwise execution
         -- can become /exponentially/ more expensive. See #11731, #12996.
-        runWhen (strictness || late_dmd_anal) CoreDoStrictness,
+        runWhen (strictness || late_dmd_anal) CoreDoDemand,
 
         maybe_rule_check (Phase 0)
      ]
@@ -445,9 +444,12 @@ doCorePass CoreDoCallArity           = {-# SCC "CallArity" #-}
 doCorePass CoreDoExitify             = {-# SCC "Exitify" #-}
                                        doPass exitifyProgram
 
-doCorePass CoreDoStrictness          = {-# SCC "NewStranal" #-}
+doCorePass CoreDoDemand              = {-# SCC "DmdAnal" #-}
                                        doPassDFM dmdAnalProgram
 
+doCorePass CoreDoCpr                 = {-# SCC "CprAnal" #-}
+                                       doPassDFM cprAnalProgram
+
 doCorePass CoreDoWorkerWrapper       = {-# SCC "WorkWrap" #-}
                                        doPassDFU wwTopBinds
 
@@ -1020,6 +1022,7 @@ transferIdInfo exported_id local_id
   where
     local_info = idInfo local_id
     transfer exp_info = exp_info `setStrictnessInfo`    strictnessInfo local_info
+                                 `setCprInfo`           cprInfo local_info
                                  `setUnfoldingInfo`     unfoldingInfo local_info
                                  `setInlinePragInfo`    inlinePragInfo local_info
                                  `setRuleInfo`          addRuleInfo (ruleInfo exp_info) new_info
diff --git a/compiler/simplCore/SimplUtils.hs b/compiler/simplCore/SimplUtils.hs
index 5c653c7adb..03c4b8ebd6 100644
--- a/compiler/simplCore/SimplUtils.hs
+++ b/compiler/simplCore/SimplUtils.hs
@@ -499,7 +499,7 @@ mkArgInfo env fun rules n_val_args call_cont
                         -- top-level bindings for (say) strings into
                         -- calls to error.  But now we are more careful about
                         -- inlining lone variables, so its ok (see SimplUtils.analyseCont)
-                   if isBotRes result_info then
+                   if isBotDiv result_info then
                         map isStrictDmd demands         -- Finite => result is bottom
                    else
                         map isStrictDmd demands ++ vanilla_stricts
@@ -1575,7 +1575,7 @@ arguments!
 
 Note [Do not eta-expand join points]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Similarly to CPR (see Note [Don't CPR join points] in WorkWrap), a join point
+Similarly to CPR (see Note [Don't w/w join points for CPR] in WorkWrap), a join point
 stands well to gain from its outer binding's eta-expansion, and eta-expanding a
 join point is fraught with issues like how to deal with a cast:
 
diff --git a/compiler/simplCore/Simplify.hs b/compiler/simplCore/Simplify.hs
index 01d802c30b..50d35149d5 100644
--- a/compiler/simplCore/Simplify.hs
+++ b/compiler/simplCore/Simplify.hs
@@ -35,14 +35,15 @@ import DataCon          ( DataCon, dataConWorkId, dataConRepStrictness
                         , StrictnessMark (..) )
 import CoreMonad        ( Tick(..), SimplMode(..) )
 import CoreSyn
-import Demand           ( StrictSig(..), dmdTypeDepth, isStrictDmd )
+import Demand           ( StrictSig(..), dmdTypeDepth, isStrictDmd
+                        , mkClosedStrictSig, topDmd, botDiv )
+import Cpr              ( mkCprSig, botCpr )
 import PprCore          ( pprCoreExpr )
 import CoreUnfold
 import CoreUtils
 import CoreOpt          ( pushCoTyArg, pushCoValArg
                         , joinPointBinding_maybe, joinPointBindings_maybe )
 import Rules            ( mkRuleInfo, lookupRule, getRules )
-import Demand           ( mkClosedStrictSig, topDmd, botRes )
 import BasicTypes       ( TopLevelFlag(..), isNotTopLevel, isTopLevel,
                           RecFlag(..), Arity )
 import MonadUtils       ( mapAccumLM, liftIO )
@@ -447,6 +448,7 @@ prepareRhs mode top_lvl occ info (Cast rhs co)  -- Note [Float coercions]
         ; return (floats, Cast rhs' co) }
   where
     sanitised_info = vanillaIdInfo `setStrictnessInfo` strictnessInfo info
+                                   `setCprInfo`        cprInfo info
                                    `setDemandInfo`     demandInfo info
 
 prepareRhs mode top_lvl occ _ rhs0
@@ -731,8 +733,10 @@ addLetBndrInfo new_bndr new_arity is_bot new_unf
           = info2
 
     -- Bottoming bindings: see Note [Bottoming bindings]
-    info4 | is_bot    = info3 `setStrictnessInfo`
-                        mkClosedStrictSig (replicate new_arity topDmd) botRes
+    info4 | is_bot    = info3
+                          `setStrictnessInfo`
+                            mkClosedStrictSig (replicate new_arity topDmd) botDiv
+                          `setCprInfo` mkCprSig new_arity botCpr
           | otherwise = info3
 
      -- Zap call arity info. We have used it by now (via