Don't use DynFlags in CmmToAsm.BlockLayout (#17957)

3 files changed, 28 insertions, 22 deletions

diff --git a/compiler/GHC/CmmToAsm.hs b/compiler/GHC/CmmToAsm.hs
index c2b32574ba..677c7bdcbf 100644
--- a/compiler/GHC/CmmToAsm.hs
+++ b/compiler/GHC/CmmToAsm.hs
@@ -644,7 +644,6 @@ cmmNativeGen dflags this_mod modLoc ncgImpl us fileIds dbgMap cmm count
                 checkLayout shorted $
                 {-# SCC "sequenceBlocks" #-}
                 map (BlockLayout.sequenceTop
-                        dflags
                         ncgImpl optimizedCFG)
                     shorted
 
@@ -1151,6 +1150,8 @@ initNCGConfig dflags = NCGConfig
    , ncgRegsIterative         = gopt Opt_RegsIterative dflags
    , ncgAsmLinting            = gopt Opt_DoAsmLinting dflags
    , ncgCfgWeights            = cfgWeights dflags
+   , ncgCfgBlockLayout        = gopt Opt_CfgBlocklayout dflags
+   , ncgCfgWeightlessLayout   = gopt Opt_WeightlessBlocklayout dflags
 
      -- With -O1 and greater, the cmmSink pass does constant-folding, so
      -- we don't need to do it again in the native code generator.
diff --git a/compiler/GHC/CmmToAsm/BlockLayout.hs b/compiler/GHC/CmmToAsm/BlockLayout.hs
index 21b6865699..2e05d2dfa9 100644
--- a/compiler/GHC/CmmToAsm/BlockLayout.hs
+++ b/compiler/GHC/CmmToAsm/BlockLayout.hs
@@ -8,6 +8,7 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE MultiWayIf #-}
 
 module GHC.CmmToAsm.BlockLayout
     ( sequenceTop, backendMaintainsCfg)
@@ -16,13 +17,13 @@ where
 #include "HsVersions.h"
 import GHC.Prelude
 
-import GHC.Driver.Session (gopt, GeneralFlag(..), DynFlags, targetPlatform)
 import GHC.Driver.Ppr     (pprTrace)
 
 import GHC.CmmToAsm.Instr
 import GHC.CmmToAsm.Monad
 import GHC.CmmToAsm.CFG
 import GHC.CmmToAsm.Types
+import GHC.CmmToAsm.Config
 
 import GHC.Cmm.BlockId
 import GHC.Cmm
@@ -817,30 +818,32 @@ dropJumps info ((BasicBlock lbl ins):todo)
 
 sequenceTop
     :: Instruction instr
-    => DynFlags -- Determine which layout algo to use
-    -> NcgImpl statics instr jumpDest
+    => NcgImpl statics instr jumpDest
     -> Maybe CFG -- ^ CFG if we have one.
     -> NatCmmDecl statics instr -- ^ Function to serialize
     -> NatCmmDecl statics instr
 
-sequenceTop _     _       _           top@(CmmData _ _) = top
-sequenceTop dflags ncgImpl edgeWeights
-            (CmmProc info lbl live (ListGraph blocks))
-  | (gopt Opt_CfgBlocklayout dflags) && backendMaintainsCfg (targetPlatform dflags)
-  --Use chain based algorithm
-  , Just cfg <- edgeWeights
-  = CmmProc info lbl live ( ListGraph $ ncgMakeFarBranches ncgImpl info $
-                            {-# SCC layoutBlocks #-}
-                            sequenceChain info cfg blocks )
-  | otherwise
-  --Use old algorithm
-  = let cfg = if dontUseCfg then Nothing else edgeWeights
-    in  CmmProc info lbl live ( ListGraph $ ncgMakeFarBranches ncgImpl info $
-                                {-# SCC layoutBlocks #-}
-                                sequenceBlocks cfg info blocks)
-  where
-    dontUseCfg = gopt Opt_WeightlessBlocklayout dflags ||
-                 (not $ backendMaintainsCfg (targetPlatform dflags))
+sequenceTop _       _           top@(CmmData _ _) = top
+sequenceTop ncgImpl edgeWeights (CmmProc info lbl live (ListGraph blocks))
+  = let
+      config     = ncgConfig ncgImpl
+      platform   = ncgPlatform config
+
+    in CmmProc info lbl live $ ListGraph $ ncgMakeFarBranches ncgImpl info $
+         if -- Chain based algorithm
+            | ncgCfgBlockLayout config
+            , backendMaintainsCfg platform
+            , Just cfg <- edgeWeights
+            -> {-# SCC layoutBlocks #-} sequenceChain info cfg blocks
+
+            -- Old algorithm without edge weights
+            | ncgCfgWeightlessLayout config
+               || not (backendMaintainsCfg platform)
+            -> {-# SCC layoutBlocks #-} sequenceBlocks Nothing info blocks
+
+            -- Old algorithm with edge weights (if any)
+            | otherwise
+            -> {-# SCC layoutBlocks #-} sequenceBlocks edgeWeights info blocks
 
 -- The old algorithm:
 -- It is very simple (and stupid): We make a graph out of
diff --git a/compiler/GHC/CmmToAsm/Config.hs b/compiler/GHC/CmmToAsm/Config.hs
index 88cff6a3eb..29d8bcad15 100644
--- a/compiler/GHC/CmmToAsm/Config.hs
+++ b/compiler/GHC/CmmToAsm/Config.hs
@@ -31,6 +31,8 @@ data NCGConfig = NCGConfig
    , ncgDumpAsmStats          :: !Bool
    , ncgDumpAsmConflicts      :: !Bool
    , ncgCfgWeights            :: !Weights         -- ^ CFG edge weights
+   , ncgCfgBlockLayout        :: !Bool            -- ^ Use CFG based block layout algorithm
+   , ncgCfgWeightlessLayout   :: !Bool            -- ^ Layout based on last instruction per block.
    }
 
 -- | Return Word size