comment wibbles

[ghc-hetmet.git] / compiler / nativeGen / RegAllocColor.hs

diff --git a/compiler/nativeGen/RegAllocColor.hs b/compiler/nativeGen/RegAllocColor.hs
index a2b98f1..35550dd 100644 (file)
--- a/compiler/nativeGen/RegAllocColor.hs
+++ b/compiler/nativeGen/RegAllocColor.hs
@@ -18,6 +18,7 @@ import RegLiveness
 import RegSpill
 import RegSpillClean
 import RegAllocStats
+-- import RegCoalesce
 import MachRegs
 import MachInstrs
 import PprMach
@@ -70,7 +71,6 @@ regAlloc_spin dflags (spinCount :: Int) triv regsFree slotsFree debug_codeGraphs
                , dopt Opt_D_dump_asm_stats dflags
                , dopt Opt_D_dump_asm_conflicts dflags ]
 
-
        -- check that we're not running off down the garden path.
        when (spinCount > maxSpinCount)
         $ pprPanic "regAlloc_spin: max build/spill cycle count exceeded."
@@ -80,8 +80,21 @@ regAlloc_spin dflags (spinCount :: Int) triv regsFree slotsFree debug_codeGraphs
                                                $ uniqSetToList $ unionManyUniqSets $ eltsUFM regsFree)
                $$ text "slotsFree   = " <> ppr (sizeUniqSet slotsFree))
 
+
+       -- Brig's algorithm does reckless coalescing for all but the first allocation stage
+       --      Doing this seems to reduce the number of reg-reg moves, but at the cost-
+       --      of creating more spills. Probably better just to stick with conservative 
+       --      coalescing in Color.colorGraph for now.
+       --
+       {- code_coalesced1      <- if (spinCount > 0) 
+                               then regCoalesce code
+                               else return code -}
+
+       let code_coalesced1     = code
+
+
        -- build a conflict graph from the code.
-       graph           <- {-# SCC "BuildGraph" #-} buildGraph code
+       graph           <- {-# SCC "BuildGraph" #-} buildGraph code_coalesced1
 
        -- VERY IMPORTANT:
        --      We really do want the graph to be fully evaluated _before_ we start coloring.
@@ -95,7 +108,7 @@ regAlloc_spin dflags (spinCount :: Int) triv regsFree slotsFree debug_codeGraphs
        --      this is lazy, it won't be computed unless we need to spill
 
        let fmLife      = {-# SCC "LifetimeCount" #-} plusUFMs_C (\(r1, l1) (_, l2) -> (r1, l1 + l2))
-                       $ map lifetimeCount code
+                       $ map lifetimeCount code_coalesced1
 
        -- record startup state
        let stat1       =
@@ -115,21 +128,22 @@ regAlloc_spin dflags (spinCount :: Int) triv regsFree slotsFree debug_codeGraphs
                        = {-# SCC "ColorGraph" #-}
                           Color.colorGraph
                                (dopt Opt_RegsIterative dflags)
+                               spinCount
                                regsFree triv spill graph
 
        -- rewrite regs in the code that have been coalesced
        let patchF reg  = case lookupUFM rmCoalesce reg of
                                Just reg'       -> patchF reg'
                                Nothing         -> reg
-       let code_coalesced
-                       = map (patchEraseLive patchF) code
+       let code_coalesced2
+                       = map (patchEraseLive patchF) code_coalesced1
 
 
        -- see if we've found a coloring
        if isEmptyUniqSet rsSpill
         then do
                -- patch the registers using the info in the graph
-               let code_patched        = map (patchRegsFromGraph graph_colored) code_coalesced
+               let code_patched        = map (patchRegsFromGraph graph_colored) code_coalesced2
 
                -- clean out unneeded SPILL/RELOADs
                let code_spillclean     = map cleanSpills code_patched
@@ -166,7 +180,7 @@ regAlloc_spin dflags (spinCount :: Int) triv regsFree slotsFree debug_codeGraphs
         else do
                -- spill the uncolored regs
                (code_spilled, slotsFree', spillStats)
-                       <- regSpill code_coalesced slotsFree rsSpill
+                       <- regSpill code_coalesced2 slotsFree rsSpill
 
                -- recalculate liveness
                let code_nat    = map stripLive code_spilled
@@ -257,7 +271,7 @@ buildGraph code
        let moveBag             = unionBags (unionManyBags moveList2) (unionManyBags moveList)
        let graph_coalesce      = foldrBag graphAddCoalesce graph_conflict moveBag
                        
-       return  $ Color.validateGraph (text "urk") graph_coalesce
+       return  graph_coalesce
 
 
 -- | Add some conflict edges to the graph.