compiler: enable generic cmm optimizations in wasm backend NCG

This commit enables the generic cmm optimizations in other NCGs to be
run in the wasm backend as well, followed by a late cmm control-flow
optimization pass. The added optimizations do catch some corner cases
not handled by the pre-NCG cmm pipeline and are useful in generating
smaller CFGs.

compiler/GHC/CmmToAsm.hs

@@ -153,7 +153,7 @@ nativeCodeGen logger ts config modLoc h us cmms
       ArchLoongArch64->panic "nativeCodeGen: No NCG for LoongArch64"
       ArchUnknown   -> panic "nativeCodeGen: No NCG for unknown arch"
       ArchJavaScript-> panic "nativeCodeGen: No NCG for JavaScript"
-      ArchWasm32    -> Wasm32.ncgWasm logger platform ts us modLoc h cmms
+      ArchWasm32    -> Wasm32.ncgWasm config logger platform ts us modLoc h cmms
 
 -- | Data accumulated during code generation. Mostly about statistics,
 -- but also collects debug data for DWARF generation.

compiler/GHC/CmmToAsm/Wasm.hs

 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE Strict #-}
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 
 module GHC.CmmToAsm.Wasm (ncgWasm) where
 
@@ -9,6 +10,9 @@ import Data.ByteString.Lazy.Char8 (unpack)
 import Data.Maybe
 import Data.Semigroup
 import GHC.Cmm
+import GHC.Cmm.ContFlowOpt
+import GHC.Cmm.GenericOpt
+import GHC.CmmToAsm.Config
 import GHC.CmmToAsm.Wasm.Asm
 import GHC.CmmToAsm.Wasm.FromCmm
 import GHC.CmmToAsm.Wasm.Types
@@ -24,6 +28,7 @@ import GHC.Utils.Outputable (text)
 import System.IO
 
 ncgWasm ::
+  NCGConfig ->
   Logger ->
   Platform ->
   ToolSettings ->
@@ -32,8 +37,8 @@ ncgWasm ::
   Handle ->
   Stream IO RawCmmGroup a ->
   IO a
-ncgWasm logger platform ts us loc h cmms = do
-  (r, s) <- streamCmmGroups platform us cmms
+ncgWasm ncg_config logger platform ts us loc h cmms = do
+  (r, s) <- streamCmmGroups ncg_config platform us cmms
   outputWasm $ "# " <> string7 (fromJust $ ml_hs_file loc) <> "\n\n"
   outputWasm $ execWasmAsmM do_tail_call $ asmTellEverything TagI32 s
   pure r
@@ -51,17 +56,26 @@ ncgWasm logger platform ts us loc h cmms = do
       hPutBuilder h builder
 
 streamCmmGroups ::
+  NCGConfig ->
   Platform ->
   UniqSupply ->
   Stream IO RawCmmGroup a ->
   IO (a, WasmCodeGenState 'I32)
-streamCmmGroups platform us cmms =
-  go (initialWasmCodeGenState platform us) $
-    runStream cmms
+streamCmmGroups ncg_config platform us cmms =
+  go (initialWasmCodeGenState platform us) $ runStream cmms
   where
     go s (Done r) = pure (r, s)
     go s (Effect m) = m >>= go s
-    go s (Yield cmm k) = go (wasmExecM (onCmmGroup cmm) s) k
+    go s (Yield decls k) = go (wasmExecM (onCmmGroup $ map opt decls) s) k
+      where
+        -- Run the generic cmm optimizations like other NCGs, followed
+        -- by a late control-flow optimization pass that does shrink
+        -- the CFG block count in some cases.
+        opt decl = case decl of
+          CmmData {} -> decl
+          CmmProc {} -> CmmProc info lbl live $ cmmCfgOpts False graph
+            where
+              (CmmProc info lbl live graph, _) = cmmToCmm ncg_config decl
 
 doTailCall :: ToolSettings -> Bool
 doTailCall ts = Option "-mtail-call" `elem` as_args