if p then True else False ===> p

plutus-core/plutus-core.cabal

@@ -538,6 +538,7 @@ library plutus-ir
     PlutusIR.Transform.RecSplit
     PlutusIR.Transform.Rename
     PlutusIR.Transform.RewriteRules
+    PlutusIR.Transform.RewriteRules.CancelIfThenTrueElseFalse
     PlutusIR.Transform.RewriteRules.CommuteFnWithConst
     PlutusIR.Transform.RewriteRules.RemoveTrace
     PlutusIR.Transform.StrictifyBindings

plutus-core/plutus-ir/src/PlutusIR/Transform/RewriteRules/CancelIfThenTrueElseFalse.hs

@@ -0,0 +1,21 @@
+{-# LANGUAGE BlockArguments  #-}
+{-# LANGUAGE LambdaCase      #-}
+{-# LANGUAGE PatternSynonyms #-}
+
+module PlutusIR.Transform.RewriteRules.CancelIfThenTrueElseFalse
+  ( rewriteRuleCancelIfThenTrueElseFalse
+  ) where
+
+import PlutusCore (someValue)
+import PlutusCore.Default (DefaultFun, DefaultUni)
+import PlutusCore.Default.Builtins qualified as Builtin
+import PlutusIR.Core.Type (Term (Constant), Type (TyBuiltin))
+import PlutusIR.Transform.RewriteRules.Common (pattern A, pattern B, pattern I)
+
+rewriteRuleCancelIfThenTrueElseFalse
+  :: Term ty name DefaultUni DefaultFun a
+  -> Term ty name DefaultUni DefaultFun a
+rewriteRuleCancelIfThenTrueElseFalse = \case
+  B Builtin.IfThenElse `I` TyBuiltin _ _ `A` p `A` Constant _ t `A` Constant _ e
+    | t == someValue True && e == someValue False -> p
+  term -> term

plutus-core/plutus-ir/src/PlutusIR/Transform/RewriteRules/Internal.hs

@@ -1,3 +1,4 @@
+-- editorconfig-checker-disable-file
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GADTs             #-}
 {-# LANGUAGE RankNTypes        #-}
@@ -12,6 +13,7 @@ import PlutusCore.Name.Unique (Name)
 import PlutusCore.Quote (MonadQuote)
 import PlutusIR.Analysis.VarInfo (VarsInfo)
 import PlutusIR.Core.Type qualified as PIR
+import PlutusIR.Transform.RewriteRules.CancelIfThenTrueElseFalse (rewriteRuleCancelIfThenTrueElseFalse)
 import PlutusIR.Transform.RewriteRules.CommuteFnWithConst (commuteFnWithConst)
 import PlutusIR.Transform.RewriteRules.UnConstrConstrData (unConstrConstrData)
 import PlutusPrelude (Default (..), (>=>))
@@ -32,7 +34,9 @@ newtype RewriteRules uni fun where
 defaultUniRewriteRules :: RewriteRules DefaultUni DefaultFun
 defaultUniRewriteRules = RewriteRules $ \varsInfo ->
   -- The rules are composed from left to right.
-  pure . commuteFnWithConst >=> unConstrConstrData def varsInfo
+  (pure . rewriteRuleCancelIfThenTrueElseFalse)
+    >=> (pure . commuteFnWithConst)
+    >=> unConstrConstrData def varsInfo
 
 instance Default (RewriteRules DefaultUni DefaultFun) where
   def = defaultUniRewriteRules

plutus-core/plutus-ir/test/PlutusIR/Transform/RewriteRules/Tests.hs

@@ -13,30 +13,27 @@ import Test.QuickCheck
 import Test.Tasty
 
 test_rewriteRules :: TestTree
-test_rewriteRules = runTestNestedIn ["plutus-ir/test/PlutusIR/Transform"] $
+test_rewriteRules =
+  runTestNestedIn ["plutus-ir/test/PlutusIR/Transform"] $
     testNested "RewriteRules" $
-    (fmap
-        (goldenPir (runQuote . runTestPass (\tc -> rewritePassSC tc def)) pTerm)
+      fmap
+        (goldenPir (runQuote . runTestPass (\tc -> rewritePassSC tc rewriteRules)) pTerm)
         [ "equalsInt.pir" -- this tests that the function works on equalInteger
         , "divideInt.pir" -- this tests that the function excludes not commutative functions
         , "multiplyInt.pir" -- this tests that the function works on multiplyInteger
         , "let.pir" -- this tests that it works in the subterms
         , "unConstrConstrDataFst.pir"
         , "unConstrConstrDataSnd.pir"
+        , "ifThenTrueElseFalse.pir"
         ]
-    )
-    ++
-    (fmap
-        (goldenPirEvalTrace pTermAsProg)
-        [ "unConstrConstrDataFst.pir.eval"
-        ]
-    )
+        ++ fmap (goldenPirEvalTrace pTermAsProg) ["unConstrConstrDataFst.pir.eval"]
+ where
+  rewriteRules = def
 
-  where
-    goldenPirEvalTrace = goldenPirM $ \ast -> ppCatch $ do
-          -- we need traces to remain for checking the evaluation-order
-          tplc <- asIfThrown $ compileWithOpts ( set (PIR.ccOpts . PIR.coPreserveLogging) True) ast
-          runUPlcLogs [void tplc]
+  goldenPirEvalTrace = goldenPirM $ \ast -> ppCatch $ do
+    -- we need traces to remain for checking the evaluation-order
+    tplc <- asIfThrown $ compileWithOpts (set (PIR.ccOpts . PIR.coPreserveLogging) True) ast
+    runUPlcLogs [void tplc]
 
 prop_rewriteRules :: Property
 prop_rewriteRules =

plutus-core/plutus-ir/test/PlutusIR/Transform/RewriteRules/ifThenTrueElseFalse.pir

@@ -0,0 +1,11 @@
+[
+  { (builtin ifThenElse) (con bool) }
+    [
+      { (builtin ifThenElse) (con bool) }
+        (con bool False)
+        (con bool True)
+        (con bool False)
+    ]
+    (con bool True)
+    (con bool False)
+]

plutus-core/plutus-ir/test/PlutusIR/Transform/RewriteRules/ifThenTrueElseFalse.pir.golden

@@ -0,0 +1 @@
+(con bool False)