Report changes in constantSpec / reduceNonRepPrim

These transformations were previously not reporting all times when
they were applied / changed the input term. However, the check for
this was only enabled with DebugApplied or higher, which meant CI
would not identify these mistakes (as CI uses DebugSilent).

Fixes #1851

Author: Alex McKenna

clash-lib/src/Clash/Normalize/PrimitiveReductions.hs

@@ -485,7 +485,7 @@ reduceIterateI (TransformContext is0 ctx) n aTy vTy f0 a = do
   --   in
   --     (a :> el1 :> el2 :> el3 :> ..)
   --
-  pure (Letrec (zip elementIds elems) vec)
+  changed (Letrec (zip elementIds elems) vec)
 
 -- | Replace an application of the @Clash.Sized.Vector.traverse#@ primitive on
 -- vectors of a known length @n@, by the fully unrolled recursive "definition"

clash-lib/src/Clash/Normalize/Transformations/Specialize.hs

@@ -22,7 +22,9 @@ module Clash.Normalize.Transformations.Specialize
 
 import qualified Control.Lens as Lens
 import Control.Monad.Extra (orM)
+import qualified Control.Monad.Writer as Writer (listen)
 import qualified Data.Either as Either
+import qualified Data.Monoid as Monoid (getAny)
 import GHC.Stack (HasCallStack)
 
 import Clash.Core.FreeVars (termFreeTyVars, typeFreeVars)
@@ -44,7 +46,7 @@ import Clash.Rewrite.Combinators (topdownR)
 import Clash.Rewrite.Types
   ( TransformContext(..), bindings, censor, customReprs, tcCache
   , typeTranslator, workFreeBinders)
-import Clash.Rewrite.Util (mkDerivedName, mkTmBinderFor, setChanged)
+import Clash.Rewrite.Util (mkDerivedName, mkTmBinderFor, setChanged, changed)
 import Clash.Rewrite.WorkFree (isWorkFree)
 import Clash.Normalize.Types (NormRewrite, NormalizeSession)
 import Clash.Normalize.Util
@@ -234,11 +236,13 @@ constantSpec ctx@(TransformContext is0 tfCtx) e@(App e1 e2)
          else do
            -- Parts of e2 are constant
            let is1 = extendInScopeSetList is0 (fst <$> csrNewBindings specInfo)
-           Letrec newBindings
-            <$> specializeNorm
-                  (TransformContext is1 tfCtx)
-                  (App e1 (csrNewTerm specInfo))
+           (body, isSpec) <- Writer.listen $ specializeNorm
+             (TransformContext is1 tfCtx)
+             (App e1 (csrNewTerm specInfo))
 
+           if Monoid.getAny isSpec
+             then changed (Letrec newBindings body)
+             else return e
        else
         -- e2 has no constant parts
         return e

clash-lib/src/Clash/Rewrite/Util.hs

@@ -275,7 +275,7 @@ applyDebug lvl _transformations _fromLimit name exprOld hasChanged exprNew =
                      ]
             ) (return ())
 
-  Monad.when (lvl >= DebugApplied && not hasChanged && not (exprOld `aeqTerm` exprNew)) $
+  Monad.when (lvl >= DebugSilent && not hasChanged && not (exprOld `aeqTerm` exprNew)) $
     error $ $(curLoc) ++ "Expression changed without notice(" ++ name ++  "): before"
                       ++ before ++ "\nafter:\n" ++ after