Add a test for #4007

testsuite/tests/ghc-regress/perf/compiler/Makefile

 TOP=../../../..
 include $(TOP)/mk/boilerplate.mk
 include $(TOP)/mk/test.mk
+
+.PHONY: T4007
+T4007:
+	$(RM) -f T4007.hi T4007.o
+	'$(TEST_HC)' -c -O -ddump-rule-firings T4007.hs
+

testsuite/tests/ghc-regress/perf/compiler/T4007.hs

+
+module T4007 where
+
+f :: IO ()
+f = sequence_ (replicate 10 (putStrLn "yes"))

testsuite/tests/ghc-regress/perf/compiler/T4007.stderr

+Rule fired: unpack
+Rule fired: Class op >>
+Rule fired: Class op return
+Rule fired: <=#
+Rule fired: fold/build
+Rule fired: unpack-list

testsuite/tests/ghc-regress/perf/compiler/all.T

@@ -101,3 +101,8 @@ test('T3064',
      compile,
      [''])
 
+test('T4007',
+     normal,
+     run_command,
+     ['$MAKE -s --no-print-directory T4007'])
+