Don't generate a state proc for an empty state.

This can happen when a function has no state itself, but only substates.

diff --git a/cλash/CLasH/VHDL/Generate.hs b/cλash/CLasH/VHDL/Generate.hs
index f89b989528bcca0db71736a47d86e6c3bf1fd778..149c6eca1fcd6e28d0e782f5af8a60ca9e61b998 100644 (file)
--- a/cλash/CLasH/VHDL/Generate.hs
+++ b/cλash/CLasH/VHDL/Generate.hs
@@ -127,9 +127,9 @@ getArchitecture fname = Utils.makeCached fname tsArchitectures $ do
   let (in_state_maybes, out_state_maybes) = unzip state_vars
   let (statementss, used_entitiess) = unzip sms
   -- Create a state proc, if needed
-  let state_proc = case (Maybe.catMaybes in_state_maybes, Maybe.catMaybes out_state_maybes) of
-        ([in_state], [out_state]) -> [AST.CSPSm $ mkStateProcSm (in_state, out_state)]
-        ([], []) -> []
+  state_proc <- case (Maybe.catMaybes in_state_maybes, Maybe.catMaybes out_state_maybes) of
+        ([in_state], [out_state]) -> mkStateProcSm (in_state, out_state)
+        ([], []) -> return []
         (ins, outs) -> error $ "Weird use of state in " ++ show fname ++ ". In: " ++ show ins ++ " Out: " ++ show outs
   -- Join the create statements and the (optional) state_proc
   let statements = concat statementss ++ state_proc
@@ -160,9 +160,12 @@ getArchitecture fname = Utils.makeCached fname tsArchitectures $ do
 
 mkStateProcSm :: 
   (CoreSyn.CoreBndr, CoreSyn.CoreBndr) -- ^ The current and new state variables
-  -> AST.ProcSm -- ^ The resulting statement
-mkStateProcSm (old, new) =
-  AST.ProcSm label [clk] [statement]
+  -> TranslatorSession [AST.ConcSm] -- ^ The resulting statements
+mkStateProcSm (old, new) = do
+  nonempty <- hasNonEmptyType old 
+  if nonempty 
+    then return [AST.CSPSm $ AST.ProcSm label [clk] [statement]]
+    else return []
   where
     label       = mkVHDLBasicId $ "state"
     clk         = mkVHDLBasicId "clock"