3 files changed, 58 insertions, 0 deletions
diff --git a/testsuite/tests/simplCore/should_compile/T22428.hs b/testsuite/tests/simplCore/should_compile/T22428.hs
new file mode 100644
index 0000000000..02cccb7f3a
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T22428.hs
@@ -0,0 +1,9 @@
+module T22428 where
+
+f :: Integer -> Integer -> Integer
+f x y = go y
+  where
+    go :: Integer -> Integer
+    go 0 = x
+    go n = go (n-1)
+    {-# INLINE go #-}
diff --git a/testsuite/tests/simplCore/should_compile/T22428.stderr b/testsuite/tests/simplCore/should_compile/T22428.stderr
new file mode 100644
index 0000000000..48ea278ae0
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T22428.stderr
@@ -0,0 +1,45 @@
+
+==================== Tidy Core ====================
+Result size of Tidy Core
+  = {terms: 32, types: 14, coercions: 0, joins: 1/1}
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T22428.f1 :: Integer
+[GblId,
+ Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
+         WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 10}]
+T22428.f1 = GHC.Num.Integer.IS 1#
+
+-- RHS size: {terms: 28, types: 10, coercions: 0, joins: 1/1}
+f :: Integer -> Integer -> Integer
+[GblId,
+ Arity=2,
+ Str=<SL><1L>,
+ Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
+         WorkFree=True, Expandable=True, Guidance=IF_ARGS [0 0] 156 0}]
+f = \ (x :: Integer) (y :: Integer) ->
+      joinrec {
+        go [InlPrag=INLINE (sat-args=1), Occ=LoopBreaker, Dmd=SC(S,L)]
+          :: Integer -> Integer
+        [LclId[JoinId(1)(Just [!])],
+         Arity=1,
+         Str=<1L>,
+         Unf=Unf{Src=StableUser, TopLvl=False, Value=True, ConLike=True,
+                 WorkFree=True, Expandable=True,
+                 Guidance=ALWAYS_IF(arity=1,unsat_ok=False,boring_ok=False)}]
+        go (ds :: Integer)
+          = case ds of wild {
+              GHC.Num.Integer.IS x1 ->
+                case x1 of {
+                  __DEFAULT -> jump go (GHC.Num.Integer.integerSub wild T22428.f1);
+                  0# -> x
+                };
+              GHC.Num.Integer.IP x1 ->
+                jump go (GHC.Num.Integer.integerSub wild T22428.f1);
+              GHC.Num.Integer.IN x1 ->
+                jump go (GHC.Num.Integer.integerSub wild T22428.f1)
+            }; } in
+      jump go y
+
+
+
diff --git a/testsuite/tests/simplCore/should_compile/all.T b/testsuite/tests/simplCore/should_compile/all.T
index 4fd57c5301..1b25c1b00b 100644
--- a/testsuite/tests/simplCore/should_compile/all.T
+++ b/testsuite/tests/simplCore/should_compile/all.T
@@ -459,6 +459,10 @@ test('T22494', [grep_errmsg(r'case') ], compile, ['-O -ddump-simpl -dsuppress-un
 test('T22491', normal, compile, ['-O2'])
 test('T21476', normal, compile, [''])
 test('T22272', normal, multimod_compile, ['T22272', '-O -fexpose-all-unfoldings -fno-omit-interface-pragmas -fno-ignore-interface-pragmas'])
+
+# go should become a join point
+test('T22428', [grep_errmsg(r'jump go') ], compile, ['-O -ddump-simpl -dsuppress-uniques -dno-typeable-binds -dsuppress-unfoldings'])
+
 test('T22459', normal, compile, [''])
 test('T22623', normal, multimod_compile, ['T22623', '-O -v0'])
 test('T22662', normal, compile, [''])