copilot-bluespec: Update Copilot.Compile.Bluespec.Compile to reflect new input/output order. Refs #677.

RyanGlScott · RyanGlScott · commit 659fc1aa215d · 2025-11-03T07:26:54.000-05:00
The current Bluespec backend leads to Verilog code that requires manual
manipulations in order to work correctly. Specifically, Copilot externs, which
are inputs to the Copilot monitoring system, are treated as _outputs_ in
Verilog, and Copilot triggers, which can be considered outputs of the
monitoring system, are treated as _inputs_. This is the opposite of the
interface that we would like users to work with, and of what other backends
generate (e.g., C99).

Now that the internals of `copilot-bluespec` have been updated to invert the
order in which Verilog inputs and outputs are declared, this commit adapts the
top-level code in `Copilot.Compile.Bluespec.Compiler` accordingly. In
particular, the `compileWith` function now generates a `&lt;Prefix&gt;.bs` file that
defines two module interfaces: one interface that contains the core methods
that will comprise the generated Verilog code, and another interface that helps
automate the process of defining a `Module Empty` value that is more suitable
for software simulation purposes.

Previously, `compileWith` generated a separate `&lt;Prefix&gt;Ifc.bs` file that
contained nothing but the module interface in isolation so that it could be
used separately from the interface's `Module` definition. This distinction no
longer makes as much sense, as in the new design, as (1) there are now multiple
interfaces, and (2) it is unlikely that the interfaces are not particularly
useful without having the `Module` definitions to accompany them. As such, this
commit now omits generating a `&lt;Prefix&gt;Ifc.bs` file, instead opting to generate
the interfaces as part of `&lt;Prefix&gt;.bs`.
diff --git a/copilot-bluespec/src/Copilot/Compile/Bluespec/Compile.hs b/copilot-bluespec/src/Copilot/Compile/Bluespec/Compile.hs
@@ -57,13 +57,11 @@ compileWith bsSettings prefix spec
 
   | otherwise
   = do let typesBsFile = render $ pPrint $ compileTypesBS bsSettings prefix spec
-           ifcBsFile   = render $ pPrint $ compileIfcBS   bsSettings prefix spec
            bsFile      = render $ pPrint $ compileBS      bsSettings prefix spec
 
        let dir = bluespecSettingsOutputDirectory bsSettings
        createDirectoryIfMissing True dir
        writeFile (dir </> specTypesPkgName prefix ++ ".bs") typesBsFile
-       writeFile (dir </> specIfcPkgName prefix ++ ".bs") ifcBsFile
        writeFile (dir </> "bs_fp.c") copilotBluespecFloatingPointC
        writeFile (dir </> "BluespecFP.bsv") copilotBluespecFloatingPointBSV
        writeFile (dir </> prefix ++ ".bs") bsFile
@@ -93,86 +91,147 @@ compile :: String -> Spec -> IO ()
 compile = compileWith mkDefaultBluespecSettings
 
 -- | Generate a @<prefix>.bs@ file from a 'Spec'. This is the main payload of
--- the Bluespec backend.
---
--- The generated Bluespec file will import a handful of files from the standard
--- library, as well as the following generated files:
---
--- * @<prefix>Ifc.bs@, which defines the interface containing the trigger
---   functions and external variables.
---
--- * @<prefix>Types.bs@, which defines any structs used in the 'Spec'.
---
--- It will also generate a @mk<prefix> :: Module <prefix>Ifc -> Module Empty@
--- function, which defines the module structure for this 'Spec'. The
--- @mk<prefix>@ function has the following structure:
---
--- * First, bind the argument of type @Module <prefix>Ifc@ so that trigger
---   functions can be invoked and external variables can be used.
---
--- * Next, declare stream buffers and indices.
---
--- * Next, declare generator functions for streams, accessor functions for
---   streams, and guard functions for triggers.
---
--- * Next, declare rules for each trigger function.
---
--- * Finally, declare a single rule that updates the stream buffers and
---   indices.
+-- the Bluespec backend. See the @copilot-bluespec/DESIGN.md@ document for a
+-- high-level description of what this file contains.
 compileBS :: BluespecSettings -> String -> Spec -> BS.CPackage
 compileBS _bsSettings prefix spec =
     BS.CPackage
       (BS.mkId BS.NoPos (fromString prefix))
       (Right [])
       (stdLibImports ++ genImports)
       []
-      [moduleDef]
+      [ ifcDef
+      , mkModuleDefPragma
+      , mkModuleDef
+      , ifcRulesDef
+      , mkModuleRulesDef
+      , addModuleRulesDef
+      ]
       []
   where
     -- import <prefix>Types
-    -- import <prefix>Ifc
     genImports :: [BS.CImport]
     genImports =
       [ BS.CImpId False $ BS.mkId BS.NoPos $ fromString
                         $ specTypesPkgName prefix
-      , BS.CImpId False $ BS.mkId BS.NoPos $ fromString
-                        $ specIfcPkgName prefix
       , BS.CImpId False $ BS.mkId BS.NoPos "BluespecFP"
       ]
 
-    moduleDef :: BS.CDefn
-    moduleDef = BS.CValueSign $
+    -- interface <prefix>Ifc {-# always_ready, always_enabled #-} =
+    --   ...
+    ifcDef :: BS.CDefn
+    ifcDef = BS.Cstruct
+               True
+               (BS.SInterface [BS.PIAlwaysRdy, BS.PIAlwaysEnabled])
+               (BS.IdK ifcId)
+               [] -- No type variables
+               ifcFields
+               [] -- No derived instances
+
+    -- {-# properties mkFibs = { verilog } #-}
+    mkModuleDefPragma :: BS.CDefn
+    mkModuleDefPragma = BS.CPragma $ BS.Pproperties mkModuleDefId [BS.PPverilog]
+
+    -- mk<prefix> :: Module <prefix>Ifc
+    -- mk<prefix> =
+    --   module
+    --     ...
+    mkModuleDef :: BS.CDefn
+    mkModuleDef = BS.CValueSign $
       BS.CDef
-        (BS.mkId BS.NoPos $ fromString $ "mk" ++ prefix)
-        -- :: Module <prefix>Ifc -> Module Empty
+        mkModuleDefId
         (BS.CQType
           []
-          (BS.tArrow
-            `BS.TAp` (BS.tModule `BS.TAp` ifcTy)
-            `BS.TAp` (BS.tModule `BS.TAp` emptyTy)))
-        [ BS.CClause [BS.CPVar ifcModId] [] $
-          BS.Cmodule BS.NoPos $
-              BS.CMStmt
-                (BS.CSBind (BS.CPVar ifcArgId) Nothing [] (BS.CVar ifcModId))
-            : map BS.CMStmt mkGlobals ++
-            [ BS.CMStmt $ BS.CSletrec genFuns
-            , BS.CMrules $ BS.Crules [] rules
-            ]
+          (BS.tModule `BS.TAp` ifcTy))
+        [ BS.CClause [] [] $
+            BS.Cmodule BS.NoPos $
+              map BS.CMStmt (mkExtWires ++ mkGlobals) ++
+                -- language-bluespec's pretty-printer will error if it
+                -- encounters a CSletrec with an empty list of definitions, so
+                -- avoid generating a CSletrec if there are no streams.
+                [ BS.CMStmt $ BS.CSletrec genFuns | not (null genFuns) ] ++
+                [ BS.CMrules $ BS.Crules [] $ maybeToList $ mkStepRule streams
+                , BS.CMinterface $
+                    BS.Cinterface
+                      BS.NoPos
+                      (Just ifcId)
+                      ifcMethodImpls
+                ]
         ]
 
-    ifcArgId = BS.mkId BS.NoPos $ fromString ifcArgName
-    ifcModId = BS.mkId BS.NoPos "ifcMod"
-
-    rules :: [BS.CRule]
-    rules = map mkTriggerRule uniqueTriggers ++ maybeToList (mkStepRule streams)
+    -- interface <prefix>RulesIfc =
+    --   ...
+    ifcRulesDef :: BS.CDefn
+    ifcRulesDef =
+      BS.Cstruct
+        True
+        (BS.SInterface [])
+        (BS.IdK ifcRulesId)
+        [] -- No type variables
+        ifcRulesFields
+        [] -- No derived instances
+
+    -- mk<prefix>Rules :: <prefix>Ifc -> <prefix>RulesIfc -> Rules
+    -- mk<prefix>Rules ifc ifcRules =
+    --   rules
+    --     ...
+    mkModuleRulesDef :: BS.CDefn
+    mkModuleRulesDef =
+      BS.CValueSign $
+        BS.CDef
+          mkModuleRulesDefId
+          (BS.CQType
+            []
+            (BS.tArrow `BS.TAp` ifcTy `BS.TAp`
+              (BS.tArrow `BS.TAp` ifcRulesTy `BS.TAp` BS.tRules)))
+          [BS.CClause
+            (map BS.CPVar [ifcArgId, ifcRulesArgId])
+            []
+            (BS.Crules
+              []
+              (map mkTriggerRule uniqueTriggers ++ map mkExtRule exts))]
+
+    -- add<prefix>Rules :: <prefix>Ifc -> <prefix>RulesIfc -> Module Empty
+    -- add<prefix>Rules ifc ifcRules = addRules (mk<prefix>Rules ifc ifcRules)
+    addModuleRulesDef :: BS.CDefn
+    addModuleRulesDef =
+      BS.CValueSign $
+        BS.CDef
+          addModuleRulesDefId
+          (BS.CQType
+            []
+            (BS.tArrow `BS.TAp` ifcTy `BS.TAp`
+              (BS.tArrow `BS.TAp` ifcRulesTy `BS.TAp`
+                (BS.tModule `BS.TAp` emptyTy))))
+          [BS.CClause
+            (map BS.CPVar [ifcArgId, ifcRulesArgId])
+            []
+            (BS.CApply
+              (BS.CVar (BS.idAddRules BS.NoPos))
+              [BS.CApply
+                (BS.CVar mkModuleRulesDefId)
+                (map BS.CVar [ifcArgId, ifcRulesArgId])])]
+
+    mkModuleDefId =
+      BS.mkId BS.NoPos $ fromString $ "mk" ++ prefix
+    mkModuleRulesDefId =
+      BS.mkId BS.NoPos $ fromString $ "mk" ++ prefix ++ "Rules"
+    addModuleRulesDefId =
+      BS.mkId BS.NoPos $ fromString $ "add" ++ prefix ++ "Rules"
 
     streams        = specStreams spec
     triggers       = specTriggers spec
     uniqueTriggers = mkUniqueTriggers triggers
     exts           = gatherExts streams triggers
 
+    -- Remove duplicates due to multiple guards for the same trigger.
+    triggersNoDups = nubBy compareTrigger triggers
+
+    ifcArgId = BS.mkId BS.NoPos $ fromString ifcArgName
+    ifcRulesArgId = BS.mkId BS.NoPos $ fromString ifcRulesArgName
+
     ifcId     = BS.mkId BS.NoPos $ fromString $ specIfcName prefix
-    ifcFields = mkSpecIfcFields triggers exts
+    ifcFields = mkSpecIfcFields uniqueTriggers exts
     ifcTy     = BS.TCon (BS.TyCon
                   { BS.tcon_name = ifcId
                   , BS.tcon_kind = Just BS.KStar
@@ -181,81 +240,85 @@ compileBS _bsSettings prefix spec =
                                      (map BS.cf_name ifcFields)
                   })
 
+    ifcRulesId = BS.mkId BS.NoPos $ fromString $ specIfcRulesName prefix
+    ifcRulesFields = mkSpecIfcRulesFields triggersNoDups exts
+    ifcRulesTy =
+      BS.TCon $
+        BS.TyCon
+          { BS.tcon_name = ifcRulesId
+          , BS.tcon_kind = Just BS.KStar
+          , BS.tcon_sort =
+              BS.TIstruct (BS.SInterface []) (map BS.cf_name ifcRulesFields)
+          }
+
     emptyTy = BS.TCon (BS.TyCon
                 { BS.tcon_name = BS.idEmpty
                 , BS.tcon_kind = Just BS.KStar
                 , BS.tcon_sort = BS.TIstruct (BS.SInterface []) []
                 })
 
+    -- Bind @Wire@ variables for each extern stream.
+    mkExtWires :: [BS.CStmt]
+    mkExtWires = map extWireStmt exts
+      where
+        extWireStmt :: External -> BS.CStmt
+        extWireStmt (External name ty) = mkExtWireDecln name ty
+
     -- Make buffer and index declarations for streams.
     mkGlobals :: [BS.CStmt]
     mkGlobals = concatMap buffDecln streams ++ map indexDecln streams
       where
         buffDecln  (Stream sId buff _ ty) = mkBuffDecln  sId ty buff
         indexDecln (Stream sId _    _ _ ) = mkIndexDecln sId
 
-    -- Make generator functions, including trigger arguments.
+    -- Make generator functions for streams.
     genFuns :: [BS.CDefl]
-    genFuns =  map accessDecln streams
-            ++ map streamGen streams
-            ++ concatMap triggerGen uniqueTriggers
+    genFuns = map accessDecln streams ++ map streamGen streams
       where
         accessDecln :: Stream -> BS.CDefl
         accessDecln (Stream sId buff _ ty) = mkAccessDecln sId ty buff
 
         streamGen :: Stream -> BS.CDefl
         streamGen (Stream sId _ expr ty) = mkGenFun (generatorName sId) expr ty
 
-        triggerGen :: UniqueTrigger -> [BS.CDefl]
-        triggerGen (UniqueTrigger uniqueName (Trigger _name guard args)) =
-            guardDef : argDefs
+    -- Make interface methods for @<prefix>Ifc@.
+    ifcMethodImpls :: [BS.CDefl]
+    ifcMethodImpls =
+        concatMap triggerMethodImpls uniqueTriggers
+          ++ map extMethodImpl exts
+      where
+        -- interface
+        --   ext val = ext_wire := val
+        extMethodImpl :: External -> BS.CDefl
+        extMethodImpl (External name _) =
+          let valId = BS.mkId BS.NoPos "val" in
+          BS.CLValue
+            (BS.mkId BS.NoPos (fromString name))
+            [BS.CClause
+              [BS.CPVar valId]
+              []
+              (BS.Cwrite
+                BS.NoPos
+                (BS.CVar (BS.mkId BS.NoPos (fromString (wireName name))))
+                (BS.CVar valId))]
+            []
+
+        -- interface
+        --   trig_guard = ...
+        --   trig_arg0 = ...
+        --   ...
+        --   trig_arg(n-1) = ...
+        triggerMethodImpls :: UniqueTrigger -> [BS.CDefl]
+        triggerMethodImpls uniqueTrigger = guardDef : argDefs
           where
+            UniqueTrigger uniqueName (Trigger _name guard args) = uniqueTrigger
+
             guardDef = mkGenFun (guardName uniqueName) guard Bool
             argDefs  = map argGen (zip (argNames uniqueName) args)
 
             argGen :: (String, UExpr) -> BS.CDefl
             argGen (argName, UExpr ty expr) = mkGenFun argName expr ty
 
--- | Generate a @<prefix>Ifc.bs@ file from a 'Spec'. This contains the
--- definition of the @<prefix>Ifc@ interface, which declares the types of all
--- trigger functions and external variables. This is put in a separate file so
--- that larger applications can use it separately.
-compileIfcBS :: BluespecSettings -> String -> Spec -> BS.CPackage
-compileIfcBS _bsSettings prefix spec =
-    BS.CPackage
-      ifcPkgId
-      (Right [])
-      (stdLibImports ++ genImports)
-      []
-      [ifcDef]
-      []
-  where
-    -- import <prefix>Types
-    genImports :: [BS.CImport]
-    genImports =
-      [ BS.CImpId False $ BS.mkId BS.NoPos $ fromString
-                        $ specTypesPkgName prefix
-      ]
-
-    ifcId     = BS.mkId BS.NoPos $ fromString $ specIfcName prefix
-    ifcPkgId  = BS.mkId BS.NoPos $ fromString $ specIfcPkgName prefix
-    ifcFields = mkSpecIfcFields triggers exts
-
-    streams  = specStreams spec
-    exts     = gatherExts streams triggers
-
-    -- Remove duplicates due to multiple guards for the same trigger.
-    triggers = nubBy compareTrigger (specTriggers spec)
-
-    ifcDef :: BS.CDefn
-    ifcDef = BS.Cstruct
-               True
-               (BS.SInterface [])
-               (BS.IdK ifcId)
-               [] -- No type variables
-               ifcFields
-               [] -- No derived instances
-
 -- | Generate a @<prefix>Types.bs@ file from a 'Spec'. This declares the types
 -- of any structs used by the Copilot specification. This is put in a separate
 -- file so that larger applications can more easily substitute their own struct
diff --git a/copilot-bluespec/src/Copilot/Compile/Bluespec/Name.hs b/copilot-bluespec/src/Copilot/Compile/Bluespec/Name.hs
@@ -10,6 +10,7 @@ module Copilot.Compile.Bluespec.Name
   , lowercaseName
   , specIfcName
   , specIfcPkgName
+  , specIfcRulesName
   , specTypesPkgName
   , streamAccessorName
   , streamElemName
@@ -35,6 +36,10 @@ specIfcName prefix = uppercaseName (specIfcPkgName prefix)
 specIfcPkgName :: String -> String
 specIfcPkgName prefix = prefix ++ "Ifc"
 
+-- | Turn a specification name into the name of its rules-specific interface.
+specIfcRulesName :: String -> String
+specIfcRulesName prefix = uppercaseName (prefix ++ "RulesIfc")
+
 -- | Turn a specification name into the name of the package that declares its
 -- struct types.
 specTypesPkgName :: String -> String
