Add SCCs to hunt down #14683

2 files changed, 48 insertions, 33 deletions

diff --git a/compiler/simplCore/Simplify.hs b/compiler/simplCore/Simplify.hs
index a60df1c0ad..f93fba6862 100644
--- a/compiler/simplCore/Simplify.hs
+++ b/compiler/simplCore/Simplify.hs
@@ -128,8 +128,8 @@ simplTopBinds env0 binds0
                 -- anything into scope, then we don't get a complaint about that.
                 -- It's rather as if the top-level binders were imported.
                 -- See note [Glomming] in OccurAnal.
-        ; env1 <- simplRecBndrs env0 (bindersOfBinds binds0)
-        ; (floats, env2) <- simpl_binds env1 binds0
+        ; env1 <- {-#SCC "simplTopBinds-simplRecBndrs" #-} simplRecBndrs env0 (bindersOfBinds binds0)
+        ; (floats, env2) <- {-#SCC "simplTopBinds-simpl_binds" #-} simpl_binds env1 binds0
         ; freeTick SimplifierDone
         ; return (floats, env2) }
   where
@@ -197,17 +197,20 @@ simplRecOrTopPair :: SimplEnv
 
 simplRecOrTopPair env top_lvl is_rec mb_cont old_bndr new_bndr rhs
   | Just env' <- preInlineUnconditionally env top_lvl old_bndr rhs env
-  = trace_bind "pre-inline-uncond" $
+  = {-#SCC "simplRecOrTopPair-pre-inline-uncond" #-}
+    trace_bind "pre-inline-uncond" $
     do { tick (PreInlineUnconditionally old_bndr)
        ; return ( emptyFloats env, env' ) }
 
   | Just cont <- mb_cont
-  = ASSERT( isNotTopLevel top_lvl && isJoinId new_bndr )
+  = {-#SCC "simplRecOrTopPair-join" #-}
+    ASSERT( isNotTopLevel top_lvl && isJoinId new_bndr )
     trace_bind "join" $
     simplJoinBind env cont old_bndr new_bndr rhs env
 
   | otherwise
-  = trace_bind "normal" $
+  = {-#SCC "simplRecOrTopPair-normal" #-}
+    trace_bind "normal" $
     simplLazyBind env top_lvl is_rec old_bndr new_bndr rhs env
 
   where
@@ -254,12 +257,12 @@ simplLazyBind env top_lvl is_rec bndr bndr1 rhs rhs_se
                         -- should eta-reduce.
 
 
-        ; (body_env, tvs') <- simplBinders rhs_env tvs
+        ; (body_env, tvs') <- {-#SCC "simplBinders" #-} simplBinders rhs_env tvs
                 -- See Note [Floating and type abstraction] in SimplUtils
 
         -- Simplify the RHS
         ; let rhs_cont = mkRhsStop (substTy body_env (exprType body))
-        ; (body_floats0, body0) <- simplExprF body_env body rhs_cont
+        ; (body_floats0, body0) <- {-#SCC "simplExprF" #-} simplExprF body_env body rhs_cont
 
               -- Never float join-floats out of a non-join let-binding
               -- So wrap the body in the join-floats right now
@@ -268,21 +271,24 @@ simplLazyBind env top_lvl is_rec bndr bndr1 rhs rhs_se
 
         -- ANF-ise a constructor or PAP rhs
         -- We get at most one float per argument here
-        ; (let_floats, body2) <- prepareRhs (getMode env) top_lvl
+        ; (let_floats, body2) <- {-#SCC "prepareRhs" #-} prepareRhs (getMode env) top_lvl
                                             (getOccFS bndr1) (idInfo bndr1) body1
         ; let body_floats2 = body_floats1 `addLetFloats` let_floats
 
         ; (rhs_floats, rhs')
             <-  if not (doFloatFromRhs top_lvl is_rec False body_floats2 body2)
                 then                    -- No floating, revert to body1
+                     {-#SCC "simplLazyBind-no-floating" #-}
                      do { rhs' <- mkLam env tvs' (wrapFloats body_floats2 body1) rhs_cont
                         ; return (emptyFloats env, rhs') }
 
                 else if null tvs then   -- Simple floating
+                     {-#SCC "simplLazyBind-simple-floating" #-}
                      do { tick LetFloatFromLet
                         ; return (body_floats2, body2) }
 
                 else                    -- Do type-abstraction first
+                     {-#SCC "simplLazyBind-type-abstraction-first" #-}
                      do { tick LetFloatFromLet
                         ; (poly_binds, body3) <- abstractFloats (seDynFlags env) top_lvl
                                                                 tvs' body_floats2 body2
@@ -850,14 +856,14 @@ simplExprF1 _ (Type ty) _
     -- The (Type ty) case is handled separately by simplExpr
     -- and by the other callers of simplExprF
 
-simplExprF1 env (Var v)        cont = simplIdF env v cont
-simplExprF1 env (Lit lit)      cont = rebuild env (Lit lit) cont
-simplExprF1 env (Tick t expr)  cont = simplTick env t expr cont
-simplExprF1 env (Cast body co) cont = simplCast env body co cont
-simplExprF1 env (Coercion co)  cont = simplCoercionF env co cont
+simplExprF1 env (Var v)        cont = {-#SCC "simplIdF" #-} simplIdF env v cont
+simplExprF1 env (Lit lit)      cont = {-#SCC "rebuild" #-} rebuild env (Lit lit) cont
+simplExprF1 env (Tick t expr)  cont = {-#SCC "simplTick" #-} simplTick env t expr cont
+simplExprF1 env (Cast body co) cont = {-#SCC "simplCast" #-} simplCast env body co cont
+simplExprF1 env (Coercion co)  cont = {-#SCC "simplCoercionF" #-} simplCoercionF env co cont
 
 simplExprF1 env (App fun arg) cont
-  = case arg of
+  = {-#SCC "simplExprF1-App" #-} case arg of
       Type ty -> do { -- The argument type will (almost) certainly be used
                       -- in the output program, so just force it now.
                       -- See Note [Avoiding space leaks in OutType]
@@ -877,7 +883,8 @@ simplExprF1 env (App fun arg) cont
                             , sc_dup = NoDup, sc_cont = cont }
 
 simplExprF1 env expr@(Lam {}) cont
-  = simplLam env zapped_bndrs body cont
+  = {-#SCC "simplExprF1-Lam" #-}
+    simplLam env zapped_bndrs body cont
         -- The main issue here is under-saturated lambdas
         --   (\x1. \x2. e) arg1
         -- Here x1 might have "occurs-once" occ-info, because occ-info
@@ -899,28 +906,30 @@ simplExprF1 env expr@(Lam {}) cont
           | otherwise = zapLamIdInfo b
 
 simplExprF1 env (Case scrut bndr _ alts) cont
-  = simplExprF env scrut (Select { sc_dup = NoDup, sc_bndr = bndr
+  = {-#SCC "simplExprF1-Case" #-}
+    simplExprF env scrut (Select { sc_dup = NoDup, sc_bndr = bndr
                                  , sc_alts = alts
                                  , sc_env = env, sc_cont = cont })
 
 simplExprF1 env (Let (Rec pairs) body) cont
   | Just pairs' <- joinPointBindings_maybe pairs
-  = simplRecJoinPoint env pairs' body cont
+  = {-#SCC "simplRecJoinPoin" #-} simplRecJoinPoint env pairs' body cont
 
   | otherwise
-  = simplRecE env pairs body cont
+  = {-#SCC "simplRecE" #-} simplRecE env pairs body cont
 
 simplExprF1 env (Let (NonRec bndr rhs) body) cont
   | Type ty <- rhs    -- First deal with type lets (let a = Type ty in e)
-  = ASSERT( isTyVar bndr )
+  = {-#SCC "simplExprF1-NonRecLet-Type" #-}
+    ASSERT( isTyVar bndr )
     do { ty' <- simplType env ty
        ; simplExprF (extendTvSubst env bndr ty') body cont }
 
   | Just (bndr', rhs') <- joinPointBinding_maybe bndr rhs
-  = simplNonRecJoinPoint env bndr' rhs' body cont
+  = {-#SCC "simplNonRecJoinPoint" #-} simplNonRecJoinPoint env bndr' rhs' body cont
 
   | otherwise
-  = simplNonRecE env bndr (rhs, env) ([], body) cont
+  = {-#SCC "simplNonRecE" #-} simplNonRecE env bndr (rhs, env) ([], body) cont
 
 {- Note [Avoiding space leaks in OutType]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -1203,17 +1212,19 @@ rebuild env expr cont
 simplCast :: SimplEnv -> InExpr -> Coercion -> SimplCont
           -> SimplM (SimplFloats, OutExpr)
 simplCast env body co0 cont0
-  = do  { co1   <- simplCoercion env co0
-        ; cont1 <- addCoerce co1 cont0
-        ; simplExprF env body cont1 }
+  = do  { co1   <- {-#SCC "simplCast-simplCoercion" #-} simplCoercion env co0
+        ; cont1 <- {-#SCC "simplCast-addCoerce" #-} addCoerce co1 cont0
+        ; {-#SCC "simplCast-simplExprF" #-} simplExprF env body cont1 }
   where
        addCoerce :: OutCoercion -> SimplCont -> SimplM SimplCont
        addCoerce co1 (CastIt co2 cont)
-         = addCoerce (mkTransCo co1 co2) cont
+         = {-#SCC "addCoerce-simple-recursion" #-}
+           addCoerce (mkTransCo co1 co2) cont
 
        addCoerce co cont@(ApplyToTy { sc_arg_ty = arg_ty, sc_cont = tail })
          | Just (arg_ty', co') <- pushCoTyArg co arg_ty
-         = do { tail' <- addCoerce co' tail
+         = {-#SCC "addCoerce-pushCoTyArg" #-}
+           do { tail' <- addCoerce co' tail
               ; return (cont { sc_arg_ty = arg_ty', sc_cont = tail' }) }
 
        addCoerce co cont@(ApplyToVal { sc_arg = arg, sc_env = arg_se
@@ -1223,7 +1234,8 @@ simplCast env body co0 cont0
          , not (isTypeLevPoly new_ty)  -- without this check, we get a lev-poly arg
                                        -- See Note [Levity polymorphism invariants] in CoreSyn
                                        -- test: typecheck/should_run/EtaExpandLevPoly
-         = do { tail' <- addCoerce co2 tail
+         = {-#SCC "addCoerce-pushCoValArg" #-}
+           do { tail' <- addCoerce co2 tail
               ; if isReflCo co1
                 then return (cont { sc_cont = tail' })
                      -- Avoid simplifying if possible;
@@ -1241,8 +1253,10 @@ simplCast env body co0 cont0
                                    , sc_cont = tail' }) } }
 
        addCoerce co cont
-         | isReflexiveCo co = return cont
-         | otherwise        = return (CastIt co cont)
+         | isReflexiveCo co = {-#SCC "addCoerce-reflexive" #-}
+                              return cont
+         | otherwise        = {-#SCC "addCoerce-other" #-}
+                              return (CastIt co cont)
                 -- It's worth checking isReflexiveCo.
                 -- For example, in the initial form of a worker
                 -- we may find  (coerce T (coerce S (\x.e))) y
diff --git a/compiler/types/TyCoRep.hs b/compiler/types/TyCoRep.hs
index 9028460078..95c2e0a26b 100644
--- a/compiler/types/TyCoRep.hs
+++ b/compiler/types/TyCoRep.hs
@@ -2163,7 +2163,8 @@ ForAllCo tv (sym h) (sym g[tv |-> tv |> sym h])
 substTyWith :: HasCallStack => [TyVar] -> [Type] -> Type -> Type
 -- Works only if the domain of the substitution is a
 -- superset of the type being substituted into
-substTyWith tvs tys = ASSERT( tvs `equalLength` tys )
+substTyWith tvs tys = {-#SCC "substTyWith" #-}
+                      ASSERT( tvs `equalLength` tys )
                       substTy (zipTvSubst tvs tys)
 
 -- | Type substitution, see 'zipTvSubst'. Disables sanity checks.
@@ -2241,7 +2242,7 @@ isValidTCvSubst (TCvSubst in_scope tenv cenv) =
 -- Note [The substitution invariant].
 checkValidSubst :: HasCallStack => TCvSubst -> [Type] -> [Coercion] -> a -> a
 checkValidSubst subst@(TCvSubst in_scope tenv cenv) tys cos a
-  = WARN( not (isValidTCvSubst subst),
+  = WARN( not ({-#SCC "isValidTCvSubst" #-} isValidTCvSubst subst),
              text "in_scope" <+> ppr in_scope $$
              text "tenv" <+> ppr tenv $$
              text "tenvFVs"
@@ -2251,7 +2252,7 @@ checkValidSubst subst@(TCvSubst in_scope tenv cenv) tys cos a
                <+> ppr (tyCoVarsOfCosSet cenv) $$
              text "tys" <+> ppr tys $$
              text "cos" <+> ppr cos )
-    WARN( not tysCosFVsInScope,
+    WARN( not ({-#SCC "tysCosFVsInScope" #-} tysCosFVsInScope),
              text "in_scope" <+> ppr in_scope $$
              text "tenv" <+> ppr tenv $$
              text "cenv" <+> ppr cenv $$
@@ -2326,7 +2327,7 @@ subst_ty :: TCvSubst -> Type -> Type
 -- Note that the in_scope set is poked only if we hit a forall
 -- so it may often never be fully computed
 subst_ty subst ty
-   = go ty
+   = {-#SCC "subst_ty" #-} go ty
   where
     go (TyVarTy tv)      = substTyVar subst tv
     go (AppTy fun arg)   = mkAppTy (go fun) $! (go arg)