elaborate accesses to fields of struct constants

CHANGELOG.md

@@ -6,6 +6,11 @@
   static prefixes, which could cause deep recursion and run out of memory on
   some designs
 
+### Other Enhancements
+
+* Added elaboration for accesses to fields of struct constants, which can
+  substantially improve performance on some designs
+
 ## v0.0.10
 
 ### Breaking Changes

src/Convert.hs

@@ -48,6 +48,7 @@ import qualified Convert.Simplify
 import qualified Convert.Stream
 import qualified Convert.StringParam
 import qualified Convert.Struct
+import qualified Convert.StructConst
 import qualified Convert.TFBlock
 import qualified Convert.Typedef
 import qualified Convert.TypeOf
@@ -114,6 +115,7 @@ initialPhases selectExclude =
     , selectExclude Job.Assert Convert.Assertion.convert
     , selectExclude Job.Always Convert.AlwaysKW.convert
     , Convert.Package.convert
+    , Convert.StructConst.convert
     , Convert.PortDecl.convert
     , Convert.ParamNoDefault.convert
     , Convert.ResolveBindings.convert

src/Convert/StructConst.hs

+{- sv2v
+ - Author: Zachary Snow <zach@zachjs.com>
+ -
+ - High-level elaboration for struct constant accesses
+ -
+ - This greatly simplifies designs with long sequences of struct parameters
+ - which extend and reference one another, as seen in BlackParrot.
+ -}
+
+module Convert.StructConst (convert) where
+
+import Control.Monad.State.Strict
+import Data.Maybe (fromMaybe)
+import Data.Tuple (swap)
+import qualified Data.Map.Strict as Map
+
+import Convert.Traverse
+import Language.SystemVerilog.AST
+
+type StructType = [Field]
+type StructValue = [(TypeOrExpr, Expr)]
+
+type Const = (StructType, StructValue)
+type Consts = Map.Map Identifier Const
+type Types = Map.Map Identifier StructType
+
+type SC = State (Types, Consts)
+
+convert :: [AST] -> [AST]
+convert = map $ traverseDescriptions convertDescription
+
+convertDescription :: Description -> Description
+convertDescription =
+    flip evalState mempty .
+    traverseModuleItemsM (traverseDeclsM elaborateDecl)
+
+insertType :: Identifier -> [Field] -> SC ()
+insertType ident typ = do
+    (types, consts) <- get
+    let types' = Map.insert ident typ types
+    put (types', consts)
+
+insertConst :: Identifier -> Const -> SC ()
+insertConst ident cnst = do
+    (types, consts) <- get
+    let consts' = Map.insert ident cnst consts
+    put (types, consts')
+
+lookupType :: Type -> SC [Field]
+lookupType (Alias ident []) = do
+    maybeFields <- gets $ Map.lookup ident . fst
+    return $ fromMaybe [] maybeFields
+lookupType (Struct (Packed Unspecified) fields []) =
+    return fields
+lookupType _ = return []
+
+lookupConst :: Identifier -> SC (Maybe Const)
+lookupConst param = gets $ Map.lookup param . snd
+
+elaborateDecl :: Decl -> SC Decl
+-- track struct type parameters
+elaborateDecl decl@(ParamType Localparam x t)
+    | Struct (Packed Unspecified) fields [] <- t =
+        insertType x fields >> return decl
+-- track and resolve struct constants
+elaborateDecl (Param Localparam t x e) = do
+    e' <- elaborateExpr e
+    fields <- lookupType t
+    when (not $ null fields) $ do
+        maybeValues <- extractStructValue e'
+        case maybeValues of
+            Just values -> insertConst x (fields, values)
+            Nothing -> return ()
+    return $ Param Localparam t x e'
+elaborateDecl decl = return decl
+
+-- extract the pattern items, including for simple aliases
+extractStructValue :: Expr -> SC (Maybe StructValue)
+extractStructValue (Pattern values) = return $ Just values
+extractStructValue (Ident param) = fmap (fmap snd) $ lookupConst param
+extractStructValue _ = return Nothing
+
+-- elaborate constant field accesses
+elaborateExpr :: Expr -> SC Expr
+elaborateExpr expr@(Dot (Ident param) field) =
+    fmap (fromMaybe expr . join . fmap (resolveParam field)) (lookupConst param)
+elaborateExpr expr =
+    traverseSinglyNestedExprsM elaborateExpr expr
+
+-- lookup value in struct constant
+resolveParam :: Identifier -> Const -> Maybe Expr
+resolveParam field (fields, values) = do
+    fieldType <- lookup field (map swap fields)
+    value <- mplus
+        (lookup (Right $ Ident field) values)
+        (lookup (Left UnknownType) values)
+    Just $ Cast (Left fieldType) value

sv2v.cabal

@@ -101,6 +101,7 @@ executable sv2v
     Convert.Stream
     Convert.StringParam
     Convert.Struct
+    Convert.StructConst
     Convert.TFBlock
     Convert.Traverse
     Convert.Typedef

test/core/struct_const.sv

+package pkg;
+    typedef struct packed {
+        integer unsigned a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z;
+    } T;
+
+    `define step(b, o, f) f: o.f == "inv" ? b.f : o.f
+    `define extend(_b, _o) '{ \
+        `step(_b, _o, a), \
+        `step(_b, _o, b), \
+        `step(_b, _o, c), \
+        `step(_b, _o, d), \
+        `step(_b, _o, e), \
+        `step(_b, _o, f), \
+        `step(_b, _o, g), \
+        `step(_b, _o, h), \
+        `step(_b, _o, i), \
+        `step(_b, _o, j), \
+        `step(_b, _o, k), \
+        `step(_b, _o, l), \
+        `step(_b, _o, m), \
+        `step(_b, _o, n), \
+        `step(_b, _o, o), \
+        `step(_b, _o, p), \
+        `step(_b, _o, q), \
+        `step(_b, _o, r), \
+        `step(_b, _o, s), \
+        `step(_b, _o, t), \
+        `step(_b, _o, u), \
+        `step(_b, _o, v), \
+        `step(_b, _o, w), \
+        `step(_b, _o, x), \
+        `step(_b, _o, y), \
+        `step(_b, _o, z) \
+    }
+
+    localparam X = 1'd0;
+    localparam Y = 1'd1;
+
+    localparam T a_cfg = '{a: X, b: X, c: X, d: X, e: X, f: X, default: Y};
+
+    `define expand(let_a, let_b) \
+        localparam T let_a``_ext = '{let_a: Y, default: "inv"}; \
+        localparam T let_b``_cfg = `extend(let_a``_cfg, let_a``_ext);
+
+    `expand(a, b)
+    `expand(b, c)
+    `expand(c, d)
+    `expand(d, e)
+    `expand(e, f)
+    `expand(f, g)
+    `expand(g, h)
+    `expand(h, i)
+    `expand(i, j)
+    `expand(j, k)
+    `expand(k, l)
+    `expand(l, m)
+    `expand(m, n)
+    `expand(n, o)
+    `expand(o, p)
+    `expand(p, q)
+    `expand(q, r)
+    `expand(r, s)
+    `expand(s, t)
+    `expand(t, u)
+    `expand(u, v)
+    `expand(v, w)
+    `expand(w, x)
+    `expand(x, y)
+    `expand(y, z)
+
+    localparam P = z_cfg.z;
+endpackage
+
+module top;
+    initial $display(pkg::P);
+endmodule

test/core/struct_const.v

+
+module top;
+    localparam P = 32'd1;
+    initial $display(P);
+endmodule