From e23b23071fc89fc8b73eee61cc06728c93375161 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke_lau@icloud.com>
Date: Sun, 2 Jun 2019 17:28:31 +0100
Subject: [PATCH] Generate the module inside the repl

The Kaleidoscope tutorial acts as a repl where each top-level expression
is evaluated when you enter it. Currently we were building up the
llvm-hs-pure AST inside our REPL, and then converting it to an actual
LLVM IR module in main when we called buildModuleT.

In order to do this line-by-line JITing, we'll need the actual LLVM
module when we enter the line. This will prepare us for the craziness
that will come in the following commits
---
 Main.hs  | 21 +++++++++++++--------
 Utils.hs |  7 +++++++
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/Main.hs b/Main.hs
index bff1c08..ee8ee60 100644
--- a/Main.hs
+++ b/Main.hs
@@ -2,6 +2,7 @@
 
 import AST as K -- K for Kaleidoscope
 import Utils
+import Control.Monad.Trans.Class
 import Control.Monad.Trans.Reader
 import Control.Monad.IO.Class
 import Data.String
@@ -25,15 +26,11 @@ import Text.Read (readMaybe)
 
 main :: IO ()
 main = do
-  mdl' <- buildModuleT "main" repl
-  withContext $ \ctx -> withHostTargetMachine $ \tm ->
-    withModuleFromAST ctx mdl' $ \mdl -> do
-      let spec = defaultCuratedPassSetSpec { optLevel = Just 3 }
-      -- this returns true if the module was modified
-      withPassManager spec $ flip runPassManager mdl
-      Text.hPutStrLn stderr . ("\n" <>) . ppllvm =<< moduleAST mdl
+  withContext $ \ctx -> withHostTargetMachine $ \tm -> do
+    ast <- runReaderT (buildModuleT "main" repl) ctx
+    return ()
 
-repl :: ModuleBuilderT IO ()
+repl :: ModuleBuilderT (ReaderT Context IO) ()
 repl = do
   liftIO $ hPutStr stderr "ready> "
   mline <- liftIO $ catchIOError (Just <$> getLine) eofHandler
@@ -45,6 +42,14 @@ repl = do
         Just ast -> do
           hoist $ buildAST ast
           mostRecentDef >>= liftIO . Text.hPutStrLn stderr . ppll
+
+          ast <- moduleSoFar "main"
+          ctx <- lift ask
+          liftIO $ withModuleFromAST ctx ast $ \mdl -> do
+            let spec = defaultCuratedPassSetSpec { optLevel = Just 3 }
+            -- this returns true if the module was modified
+            withPassManager spec $ flip runPassManager mdl
+            Text.hPutStrLn stderr . ("\n" <>) . ppllvm =<< moduleAST mdl
       repl
   where
     eofHandler e
diff --git a/Utils.hs b/Utils.hs
index 2a83c35..3bd3b37 100644
--- a/Utils.hs
+++ b/Utils.hs
@@ -4,11 +4,18 @@ Shoving away gross stuff into this one module.
 module Utils where
 
 import Control.Monad.Trans.State
+import Data.ByteString.Short (ShortByteString)
 import Data.Functor.Identity
 import LLVM.AST
 import LLVM.IRBuilder.Module
 import LLVM.IRBuilder.Internal.SnocList
 
+moduleSoFar :: MonadModuleBuilder m => ShortByteString -> m Module
+moduleSoFar nm = do
+  s <- liftModuleState get
+  let ds = getSnocList (builderDefs s)
+  return $ defaultModule { moduleName = nm, moduleDefinitions = ds }
+
 mostRecentDef :: Monad m => ModuleBuilderT m Definition
 mostRecentDef = last . getSnocList . builderDefs <$> liftModuleState get
 
-- 
2.30.2