From b2f001aea8a17de1564bb9028a1951931336aa82 Mon Sep 17 00:00:00 2001
From: Ilya Rezvov <rezvov.ilya@gmail.com>
Date: Sun, 5 Jun 2022 21:45:58 -0600
Subject: [PATCH] implement table.copy

---
 src/Language/Wasm/Interpreter.hs | 18 +++++++++++++++++-
 src/Language/Wasm/Parser.y       |  4 ++--
 src/Language/Wasm/Validate.hs    |  2 +-
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/Language/Wasm/Interpreter.hs b/src/Language/Wasm/Interpreter.hs
index 9828ef9..907e2ef 100644
--- a/src/Language/Wasm/Interpreter.hs
+++ b/src/Language/Wasm/Interpreter.hs
@@ -929,9 +929,25 @@ eval budget store FunctionInstance { funcType, moduleInstance, code = Function {
                 || isDeclarative mode
             then return Trap
             else do
-                Vector.iforM_ (Vector.slice src len refs) $ \idx (RF fn) ->
+                Vector.iforM_ (Vector.slice src len refs) $ \idx (RF fn) -> do
                     MVector.unsafeWrite items (dst + idx) (fromIntegral <$> fn)
                 return $ Done ctx { stack = rest }
+        step ctx@EvalCtx{ stack = (VI32 n:VI32 s:VI32 d:rest) } (TableCopy toIdx fromIdx) = do
+            let fromAddr = tableaddrs moduleInstance ! fromIntegral fromIdx
+            let TableInstance { items = fromItems } = tableInstances store ! fromAddr
+            let toAddr = tableaddrs moduleInstance ! fromIntegral toIdx
+            let TableInstance { items = toItems } = tableInstances store ! toAddr
+            let src = fromIntegral s
+            let dst = fromIntegral d
+            let len = fromIntegral n
+            if src + len > MVector.length fromItems || dst + len > MVector.length toItems
+            then return Trap
+            else do
+                let range = if dst <= src then [0..len - 1] else reverse [0..len - 1]
+                flip mapM_ range $ \off -> do
+                    el <- MVector.unsafeRead fromItems (src + off)
+                    MVector.unsafeWrite toItems (dst + off) el
+                return $ Done ctx { stack = rest }
         step ctx@EvalCtx{ stack = (ref:VI32 offset:rest) } (TableSet tableIdx) = do
             let tableAddr = tableaddrs moduleInstance ! fromIntegral tableIdx
             let TableInstance { items } = tableInstances store ! tableAddr
diff --git a/src/Language/Wasm/Parser.y b/src/Language/Wasm/Parser.y
index 4c345ee..a06baf2 100644
--- a/src/Language/Wasm/Parser.y
+++ b/src/Language/Wasm/Parser.y
@@ -1722,11 +1722,11 @@ desugarize fields = do
                         Just elemIdx -> return $ S.TableInit tableIdx elemIdx
                         Nothing -> Left "unknown elem"
                 Nothing -> Left "unknown table"
-        synInstrToStruct FunCtx { ctxMod } (PlainInstr (TableCopy fromIdx toIdx)) =
+        synInstrToStruct FunCtx { ctxMod } (PlainInstr (TableCopy toIdx fromIdx)) =
             case getTableIndex ctxMod fromIdx of
                 Just fromIdx ->
                     case getTableIndex ctxMod toIdx of
-                        Just toIdx -> return $ S.TableCopy fromIdx toIdx
+                        Just toIdx -> return $ S.TableCopy toIdx fromIdx
                         Nothing -> Left "unknown table"
                 Nothing -> Left "unknown table"
         synInstrToStruct FunCtx { ctxMod } (PlainInstr (TableSet tableIdx)) =
diff --git a/src/Language/Wasm/Validate.hs b/src/Language/Wasm/Validate.hs
index 0591b2b..6eb9091 100644
--- a/src/Language/Wasm/Validate.hs
+++ b/src/Language/Wasm/Validate.hs
@@ -379,7 +379,7 @@ getInstrType (TableInit tableIdx elemIdx) = do
     let elemType = elems !! fromIntegral elemIdx
     when (elemType /= tableType) $ throwError (RefTypeMismatch tableType elemType)
     return $ [I32, I32, I32] ==> empty
-getInstrType (TableCopy fromIdx toIdx) = do
+getInstrType (TableCopy toIdx fromIdx) = do
     Ctx { tables } <- ask
     let (from, to) = (fromIntegral fromIdx, fromIntegral toIdx)
     when (length tables <= from) $ throwError (TableIndexOutOfRange fromIdx)