Speculative evaluate thunks known to Converge

This is an attempt to use the by-products of nested cpr analysis.

compiler/basicTypes/Demand.lhs

@@ -27,9 +27,9 @@ module Demand (
         peelFV,
 
         DmdResult, CPRResult,
-        isBotRes, isTopRes, resTypeArgDmd,
+        isBotRes, isTopRes, resTypeArgDmd, 
         topRes, convRes, botRes, cprProdRes, vanillaCprProdRes, cprSumRes,
-        appIsBottom, isBottomingSig, isConvSig, pprIfaceStrictSig,
+        appIsBottom, isBottomingSig, isConvSig, pprIfaceStrictSig, 
         trimCPRInfo, returnsCPR, returnsCPR_maybe,
         StrictSig(..), mkStrictSig, mkClosedStrictSig, nopSig, botSig, cprProdSig, convergeSig,
         isNopSig, splitStrictSig, increaseStrictSigArity,
@@ -812,6 +812,10 @@ isBotRes :: DmdResult -> Bool
 isBotRes Diverges = True
 isBotRes _        = False
 
+isConvRes :: DmdResult -> Bool
+isConvRes (Converges {}) = True
+isConvRes _              = False
+
 trimCPRInfo :: Bool -> Bool -> DmdResult -> DmdResult
 trimCPRInfo trim_all trim_sums res
   = trimR res
@@ -1439,6 +1443,9 @@ isNopSig (StrictSig ty) = isNopDmdType ty
 isBottomingSig :: StrictSig -> Bool
 isBottomingSig (StrictSig (DmdType _ _ res)) = isBotRes res
 
+isConvSig :: StrictSig -> Bool
+isConvSig (StrictSig (DmdType _ _ res)) = isConvRes res
+
 nopSig, botSig :: StrictSig
 nopSig = StrictSig nopDmdType
 botSig = StrictSig botDmdType

compiler/basicTypes/Id.lhs

@@ -47,7 +47,7 @@ module Id (
 
         -- ** Predicates on Ids
         isImplicitId, isDeadBinder, 
-        isStrictId,
+        isStrictId, isConvId,
         isExportedId, isLocalId, isGlobalId,
         isRecordSelector, isNaughtyRecordSelector,
         isClassOpId_maybe, isDFunId,
@@ -495,6 +495,11 @@ isStrictId id
            -- Take the best of both strictnesses - old and new               
            (isStrictDmd (idDemandInfo id))
 
+isConvId :: Id -> Bool
+isConvId id
+  = ASSERT2( isId id, text "isConvId: not an id: " <+> ppr id )
+           (isConvSig (idStrictness id))
+
         ---------------------------------
         -- UNFOLDING
 idUnfolding :: Id -> Unfolding

compiler/simplCore/Simplify.lhs

@@ -1347,7 +1347,7 @@ simplNonRecE env bndr (rhs, rhs_se) (bndrs, body) cont
                 ; -- pprTrace "preInlineUncond" (ppr bndr <+> ppr rhs) $
                   simplLam (extendIdSubst env bndr (mkContEx rhs_se rhs)) bndrs body cont }
 
-          | isStrictId bndr ->           -- Includes coercions
+          | isStrictId bndr || isConvId bndr ->  -- Includes coercions
             do  { simplExprF (rhs_se `setFloats` env) rhs
                              (StrictBind bndr bndrs body env cont) }