Test Trac #3717

testsuite/tests/ghc-regress/simplCore/should_compile/T3717.hs

+-- This tests whether a supurious `seq` is eliminated
+
+-- The test output is -ddump-simpl with uniques suppressed,
+-- so it may wobble a bit and require updating
+
+module T3717 where
+
+foo :: Int -> Int
+foo 0 = 0
+foo n = (if n < 5 then 1 else 2) `seq` foo (n-1)

testsuite/tests/ghc-regress/simplCore/should_compile/T3717.stderr

+
+==================== Tidy Core ====================
+lvl :: GHC.Integer.Type.Integer
+[GblId, Caf=NoCafRefs, Str=DmdType]
+lvl = GHC.Integer.Type.S# 1
+
+lvl1 :: GHC.Integer.Type.Integer
+[GblId, Caf=NoCafRefs, Str=DmdType]
+lvl1 = GHC.Integer.Type.S# 2
+
+Rec {
+T3717.$wfoo [Occ=LoopBreaker] :: GHC.Prim.Int# -> GHC.Prim.Int#
+[GblId, Arity=1, Caf=NoCafRefs, Str=DmdType L]
+T3717.$wfoo =
+  \ (ww :: GHC.Prim.Int#) ->
+    case ww of ds {
+      __DEFAULT ->
+        case case GHC.Prim.<# ds 5 of _ {
+               GHC.Bool.False -> lvl1; GHC.Bool.True -> lvl
+             }
+        of _ { __DEFAULT ->
+        T3717.$wfoo (GHC.Prim.-# ds 1)
+        };
+      0 -> 0
+    }
+end Rec }
+
+T3717.foo :: GHC.Types.Int -> GHC.Types.Int
+[GblId,
+ Arity=1,
+ Caf=NoCafRefs,
+ Str=DmdType U(L)m,
+ Unf=Unf{Src=Worker=T3717.$wfoo, TopLvl=True, Arity=1, Value=True,
+         ConLike=True, Cheap=True, Expandable=True,
+         Guidance=ALWAYS_IF(sat_ok=True,boring_ok=False)
+         Tmpl= \ (w [Occ=Once!] :: GHC.Types.Int) ->
+                 case w of _ { GHC.Types.I# ww [Occ=Once] ->
+                 case T3717.$wfoo ww of ww1 { __DEFAULT -> GHC.Types.I# ww1 }
+                 }}]
+T3717.foo =
+  \ (w :: GHC.Types.Int) ->
+    case w of _ { GHC.Types.I# ww ->
+    case T3717.$wfoo ww of ww1 { __DEFAULT -> GHC.Types.I# ww1 }
+    }
+
+
+

testsuite/tests/ghc-regress/simplCore/should_compile/all.T

@@ -59,3 +59,8 @@ test('T3234',
      compile,
      ['-ddump-simpl-stats -dsuppress-uniques -fno-code'])
 
+test('T3717', only_ways(['optc','optasm']), 
+              compile, 
+              ['-ddump-simpl -dsuppress-uniques -fno-code'])
+
+