Move loop-breaker info from original function to worker in work/wrap

When doing a w/w split, if the original function is a loop breaker
then the worker (not the wrapper) becomes one instead.

This isn't very important, because loop breaker information is
recalculated afresh by the occurrence analyser, but it seems more
kosher.  And Lint was bleating piteously about things with InlineRules
that were loop breakers.

diff --git a/compiler/stranal/WorkWrap.lhs b/compiler/stranal/WorkWrap.lhs
index 33ca298..2547978 100644 (file)
--- a/compiler/stranal/WorkWrap.lhs
+++ b/compiler/stranal/WorkWrap.lhs
@@ -11,10 +11,7 @@ import CoreUnfold    ( certainlyWillInline, mkInlineRule, mkWwInlineRule )
 import CoreUtils       ( exprType, exprIsHNF )
 import CoreArity       ( exprArity )
 import Var
-import Id              ( idType, isOneShotLambda, idUnfolding,
-                         setIdStrictness, mkWorkerId, setInlinePragma,
-                         setInlineActivation, setIdUnfolding,
-                         setIdArity )
+import Id
 import Type            ( Type )
 import IdInfo
 import Demand           ( Demand(..), StrictSig(..), DmdType(..), DmdResult(..), 
@@ -292,6 +289,12 @@ splitFun fn_id fn_info wrap_dmds res_info rhs
     ; let
        work_rhs = work_fn rhs
        work_id  = mkWorkerId work_uniq fn_id (exprType work_rhs) 
+                       `setIdOccInfo` occInfo fn_info
+                               -- Copy over occurrence info from parent
+                               -- Notably whether it's a loop breaker
+                               -- Doesn't matter much, since we will simplify next, but
+                               -- seems right-er to do so
+
                        `setInlineActivation` (inlinePragmaActivation inl_prag)
                                -- Any inline activation (which sets when inlining is active) 
                                -- on the original function is duplicated on the worker
@@ -320,6 +323,9 @@ splitFun fn_id fn_info wrap_dmds res_info rhs
                                -- The RuleMatchInfo is (and must be) unaffected
                                -- The inl_inline is bound to be False, else we would not be
                                --    making a wrapper
+                         `setIdOccInfo` NoOccInfo
+                               -- Zap any loop-breaker-ness, to avoid bleating from Lint
+                               -- about a loop breaker with an INLINE rule
 
     ; return ([(work_id, work_rhs), (wrap_id, wrap_rhs)]) })
        -- Worker first, because wrapper mentions it