clash-ffi: fix example (#2445)

* Add missing SimAction arguments

* Fix FFI example termination

* Fix `ffi:example` CI

It did not check the exit codes, continuing after an error and
ultimately reporting success.

`ffi:example` does not profit from having the `build` job's artifact
available, so we remove that dependency. Now `ffi:example` can run
earlier in the CI pipeline.

`ffi:interface-tests` is moved to public runners as it runs in a single
minute.

---------

Co-authored-by: Felix Klein <felix@qbaylogic.com>
Co-authored-by: Peter Lebbing <peter@digitalbrains.com>

.ci/gitlab/test.yml

@@ -96,6 +96,11 @@ prelude:doctests:
   script:
     - ./dist-newstyle/build/*/*/clash-prelude-*/t/doctests/build/doctests/doctests -j${THREADS}
 
+ffi:interface-tests:
+  extends: .test-nocache
+  script:
+    - ./dist-newstyle/build/*/*/clash-ffi-*/x/ffi-interface-tests/build/ffi-interface-tests/ffi-interface-tests --smallcheck-max-count 2000
+
 # Tests run on local fast machines:
 
 # Normally, this job is small. But it is flaky on GHC 9.2; it sometimes fails
@@ -133,18 +138,30 @@ suite:cores:
     - local
     - vivado-2022.1-standard
 
-ffi:interface-tests:
-  extends: .test-cache-local
+ffi:example:
+  extends: .common-local
+  stage: test
+  needs: []
+  before_script:
+    - unset SNAPCRAFT_LOGIN_FILE
+    - unset HACKAGE_PASSWORD
+    - export THREADS=$(./.ci/effective_cpus.sh)
+    - export CABAL_JOBS=$(./.ci/effective_cpus.sh)
+    - export clash_lib_datadir=$(pwd)/clash-lib/
+    - export clash_cosim_datadir=$(pwd)/clash-cosim/
+    - export MASKBINS="$(mktemp -d)"
+    - PATH="$MASKBINS:$PATH"
+    - export
+    - tar -xf cache.tar.zst -C / || true
+      # The iverilog on CI cannot run the example, we only test it builds
+    - ln -s /bin/true "$MASKBINS/iverilog"
+    - ln -s /bin/true "$MASKBINS/vvp"
+    - ls -al "$MASKBINS"
+    - .ci/setup.sh
   script:
-    - ./dist-newstyle/build/*/*/clash-ffi-*/x/ffi-interface-tests/build/ffi-interface-tests/ffi-interface-tests --smallcheck-max-count 2000
-
-# Disabled for now. The test is faulty and so is the tested code. This will be
-# fixed later.
-#ffi:example:
-#  extends: .test-cache-local
-#  script:
-#    - cabal build clash # ensure clash has been built (avoids some legacy cabal issue)
-#    - cd clash-ffi/example && ./run-iverilog.sh
+     - cd clash-ffi/example && ./run-iverilog.sh
+  after_script:
+    - tar -cf - /root/.cabal | zstd -T${THREADS} -3 > cache.tar.zst
 
 # Tests run on local fast machines with Vivado installed. We only run these at night
 # to save resources - as Vivado is quite slow to execute.

clash-ffi/example/Simulate.hs

@@ -7,7 +7,8 @@ import Data.Coerce (Coercible)
 import Data.Typeable (Typeable)
 import Data.Bits (complement)
 import Data.List (intercalate, zip5)
-import Control.Monad (when, void)
+import Control.Exception (SomeException, try)
+import Control.Monad (void)
 import Control.Monad.IO.Class (liftIO)
 import Foreign.C.String (newCString)
 import Foreign.Marshal.Alloc (free)
@@ -23,6 +24,7 @@ import Clash.FFI.Monad
 import Clash.FFI.VPI.Info
 import Clash.FFI.VPI.IO
 import Clash.FFI.VPI.Callback
+import Clash.FFI.VPI.Control
 import Clash.FFI.VPI.Module
 import Clash.FFI.VPI.Object
 import Clash.FFI.VPI.Port
@@ -106,16 +108,6 @@ ffiMain = runSimAction $ do
   putStrLn " STEP ; CLK  ; RST  ; ENB  ;         OPC          ;        RESULT"
   putStrLn "------;------;------;------;----------------------;----------------------"
 
-  void $ registerCallback
-    CallbackInfo
-      { cbReason  = EndOfSimulation
-      , cbRoutine = const $ do
-          runSimAction (putStrLn "" >> putStrLn "[ Simulation done ]")
-          return 0
-      , cbIndex   = 0
-      , cbData    = B.empty
-      }
-
   nextCB ReadWriteSynch 0 assignInputs
 
  where
@@ -130,7 +122,7 @@ ffiMain = runSimAction $ do
     4 -> "<=>" -- mixed input-output
     _ -> "x"   -- no direction
 
-assignInputs :: (?state :: State) => SimAction
+assignInputs :: (?state :: State) => SimAction ()
 assignInputs = do
   SimTime time <- receiveTime Sim $ Just top
 
@@ -171,7 +163,7 @@ assignInputs = do
     sendValue port (BitVectorVal SNat $ pack v) $ InertialDelay $ SimTime 0
     return $ Just v
 
-readOutputs :: (?state :: State) => SimAction
+readOutputs :: (?state :: State) => SimAction ()
 readOutputs = do
   SimTime time <- receiveTime Sim $ Just top
   receiveValue VectorFmt dataOut >>= \case
@@ -182,9 +174,15 @@ readOutputs = do
         }
     _ -> return ()
 
-  when (steps > 0) $ do
+  if (steps > 0) then do
     let ?state = ?state { steps = steps - 1 }
     nextCB ReadWriteSynch 1 assignInputs
+  else do
+    putStrLn ""
+    putStrLn "[ Simulation done ]"
+
+    liftIO $ void $ try @SomeException $ runSimAction
+      $ controlSimulator $ Finish NoDiagnostics
 
  where
   State{..} = ?state
@@ -228,8 +226,8 @@ updates = Updates 0 Nothing Nothing Nothing Nothing Nothing
 nextCB ::
   (Maybe Object -> Time -> CallbackReason) ->
   Int64 ->
-  SimAction ->
-  SimAction
+  SimAction () ->
+  SimAction ()
 nextCB reason time action =
   void $ registerCallback
     CallbackInfo
@@ -248,11 +246,11 @@ getByName m name = do
   liftIO $ free ref
   return obj
 
-putStr :: String -> SimAction
+putStr :: String -> SimAction ()
 putStr = simPutStr . B.pack
 
-putStrLn :: String -> SimAction
+putStrLn :: String -> SimAction ()
 putStrLn = simPutStrLn . B.pack
 
-print :: Show a => a -> SimAction
+print :: Show a => a -> SimAction ()
 print = simPutStrLn . B.pack . show

clash-ffi/example/cabal.project

@@ -1 +1,3 @@
 packages: . .. ../../clash-ghc ../../clash-lib ../../clash-prelude
+
+write-ghc-environment-files: always

clash-ffi/example/run-iverilog.sh

@@ -27,9 +27,10 @@ EXAMPLES=../../examples
 
 ###############################
 
-${CABAL} build clash-ffi-example
-${CLASH} --verilog -i${EXAMPLES} ${EXAMPLES}/Calculator.hs
-${IVERILOG} verilog/Calculator.topEntity/topEntity.v -o Calculator.vvp
+${CABAL} build clash-ffi-example || exit $?
+${CLASH} --verilog -i${EXAMPLES} ${EXAMPLES}/Calculator.hs || exit $?
+${IVERILOG} verilog/Calculator.topEntity/topEntity.v -o Calculator.vvp \
+  || exit $?
 echo ""
 echo "Running Icarus Verilog VVP runtime engine:"
 echo ""

clash-ffi/example/run-vsim.sh

@@ -0,0 +1,37 @@
+#!/bin/sh
+
+# This is just a minimalistic script for demonstrating the process of
+# running the clash-ffi example using the ModelSim / QuestaSim runtime
+# engine. The script is not designed to work in any possible system
+# environment and may not work immediately for you. It is intended to
+# serve as an easy starter instead. Adapt it to your needs if it's not
+# working out-of-the-box for you.
+
+###############################
+
+# Adjust these variables if the tools are not in your PATH already
+
+# Cabal
+# https://www.haskell.org/cabal
+CABAL=cabal
+# Clash
+# https://github.com/clash-lang/clash-compiler
+CLASH="${CABAL} run clash --"
+# ModelSim / QuestaSim binaries
+VLIB=vlib
+VLOG=vlog
+VSIM=vsim
+# Clash examples folder
+# https://github.com/clash-lang/clash-compiler/tree/master/examples
+EXAMPLES=../../examples
+
+###############################
+
+${CABAL} build clash-ffi-example || exit $?
+${CLASH} --verilog -i${EXAMPLES} ${EXAMPLES}/Calculator.hs || exit $?
+${VLIB} work || exit $?
+${VLOG} verilog/Calculator.topEntity/topEntity.v || exit $?
+echo ""
+echo "Running Simulation Runtime Engine:"
+echo ""
+${VSIM} -no_autoacc -c -do "onfinish exit; run -all" topEntity -pli lib/libclash-ffi-example.vpl