Snapshot of codegen refactoring to share with simonpj
[ghc.git] / compiler / cmm / CmmPipeline.hs
1 {-# OPTIONS_GHC -XNoMonoLocalBinds #-}
2 -- Norman likes local bindings
3 -- If this module lives on I'd like to get rid of this flag in due course
4
5 module CmmPipeline (
6 -- | Converts C-- with an implicit stack and native C-- calls into
7 -- optimized, CPS converted and native-call-less C--. The latter
8 -- C-- can be used to generate assembly.
9 cmmPipeline
10 ) where
11
12 import CLabel
13 import Cmm
14 import CmmLive
15 import CmmBuildInfoTables
16 import CmmCommonBlockElim
17 import CmmProcPoint
18 import CmmSpillReload
19 import CmmRewriteAssignments
20 import CmmStackLayout
21 import CmmContFlowOpt
22 import OptimizationFuel
23
24 import DynFlags
25 import ErrUtils
26 import HscTypes
27 import Data.Maybe
28 import Control.Monad
29 import Data.Map (Map)
30 import qualified Data.Map as Map
31 import Outputable
32 import StaticFlags
33
34 -----------------------------------------------------------------------------
35 -- | Top level driver for C-- pipeline
36 -----------------------------------------------------------------------------
37 -- There are two complications here:
38 -- 1. We need to compile the procedures in two stages because we need
39 -- an analysis of the procedures to tell us what CAFs they use.
40 -- The first stage returns a map from procedure labels to CAFs,
41 -- along with a closure that will compute SRTs and attach them to
42 -- the compiled procedures.
43 -- The second stage is to combine the CAF information into a top-level
44 -- CAF environment mapping non-static closures to the CAFs they keep live,
45 -- then pass that environment to the closures returned in the first
46 -- stage of compilation.
47 -- 2. We need to thread the module's SRT around when the SRT tables
48 -- are computed for each procedure.
49 -- The SRT needs to be threaded because it is grown lazily.
50 -- 3. We run control flow optimizations twice, once before any pipeline
51 -- work is done, and once again at the very end on all of the
52 -- resulting C-- blocks. EZY: It's unclear whether or not whether
53 -- we actually need to do the initial pass.
54 cmmPipeline :: HscEnv -- Compilation env including
55 -- dynamic flags: -dcmm-lint -ddump-cps-cmm
56 -> (TopSRT, [CmmPgm]) -- SRT table and accumulating list of compiled procs
57 -> CmmPgm -- Input C-- with Procedures
58 -> IO (TopSRT, [CmmPgm]) -- Output CPS transformed C--
59 cmmPipeline hsc_env (topSRT, rst) prog =
60 do let dflags = hsc_dflags hsc_env
61 --
62 showPass dflags "CPSZ"
63
64 let tops = runCmmContFlowOpts prog
65 (cafEnvs, tops) <- liftM unzip $ mapM (cpsTop hsc_env) tops
66 -- tops :: [[(CmmTop,CAFSet]] (one list per group)
67
68 let topCAFEnv = mkTopCAFInfo (concat cafEnvs)
69
70 -- folding over the groups
71 (topSRT, tops) <- foldM (toTops hsc_env topCAFEnv) (topSRT, []) tops
72
73 let cmms = reverse (concat tops)
74
75 dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "Post CPS Cmm" (pprPlatform (targetPlatform dflags) cmms)
76
77 -- SRT is not affected by control flow optimization pass
78 let prog' = runCmmContFlowOpts cmms
79
80 return (topSRT, prog' : rst)
81
82 {- [Note global fuel]
83 ~~~~~~~~~~~~~~~~~~~~~
84 The identity and the last pass are stored in
85 mutable reference cells in an 'HscEnv' and are
86 global to one compiler session.
87 -}
88
89 -- EZY: It might be helpful to have an easy way of dumping the "pre"
90 -- input for any given phase, besides just turning it all on with
91 -- -ddump-cmmz
92
93 cpsTop :: HscEnv -> CmmTop -> IO ([(CLabel, CAFSet)], [(CAFSet, CmmTop)])
94 cpsTop _ p@(CmmData {}) = return ([], [(Map.empty, p)])
95 cpsTop hsc_env (CmmProc h@(TopInfo {stack_info=StackInfo {arg_space=entry_off}}) l g) =
96 do
97 -- Why bother doing these early: dualLivenessWithInsertion,
98 -- insertLateReloads, rewriteAssignments?
99
100 ----------- Eliminate common blocks -------------------
101 g <- return $ elimCommonBlocks g
102 dumpPlatform platform Opt_D_dump_cmmz_cbe "Post common block elimination" g
103 -- Any work storing block Labels must be performed _after_ elimCommonBlocks
104
105 ----------- Proc points -------------------
106 let callPPs = callProcPoints g
107 procPoints <- run $ minimalProcPointSet (targetPlatform dflags) callPPs g
108 g <- run $ addProcPointProtocols callPPs procPoints g
109 dumpPlatform platform Opt_D_dump_cmmz_proc "Post Proc Points Added" g
110
111 ----------- Spills and reloads -------------------
112 g <- run $ dualLivenessWithInsertion procPoints g
113 dumpPlatform platform Opt_D_dump_cmmz_spills "Post spills and reloads" g
114
115 ----------- Sink and inline assignments -------------------
116 g <- runOptimization $ rewriteAssignments g
117 dumpPlatform platform Opt_D_dump_cmmz_rewrite "Post rewrite assignments" g
118
119 ----------- Eliminate dead assignments -------------------
120 g <- runOptimization $ removeDeadAssignments g
121 dumpPlatform platform Opt_D_dump_cmmz_dead "Post remove dead assignments" g
122
123 ----------- Zero dead stack slots (Debug only) ---------------
124 -- Debugging: stubbing slots on death can cause crashes early
125 g <- if opt_StubDeadValues
126 then run $ stubSlotsOnDeath g
127 else return g
128 dumpPlatform platform Opt_D_dump_cmmz_stub "Post stub dead stack slots" g
129
130 --------------- Stack layout ----------------
131 slotEnv <- run $ liveSlotAnal g
132 let spEntryMap = getSpEntryMap entry_off g
133 mbpprTrace "live slot analysis results: " (ppr slotEnv) $ return ()
134 let areaMap = layout procPoints spEntryMap slotEnv entry_off g
135 mbpprTrace "areaMap" (ppr areaMap) $ return ()
136
137 ------------ Manifest the stack pointer --------
138 g <- run $ manifestSP spEntryMap areaMap entry_off g
139 dumpPlatform platform Opt_D_dump_cmmz_sp "Post manifestSP" g
140 -- UGH... manifestSP can require updates to the procPointMap.
141 -- We can probably do something quicker here for the update...
142
143 ------------- Split into separate procedures ------------
144 procPointMap <- run $ procPointAnalysis procPoints g
145 dump Opt_D_dump_cmmz_procmap "procpoint map" procPointMap
146 gs <- run $ splitAtProcPoints l callPPs procPoints procPointMap
147 (CmmProc h l g)
148 mapM_ (dumpPlatform platform Opt_D_dump_cmmz_split "Post splitting") gs
149
150 ------------- More CAFs and foreign calls ------------
151 cafEnv <- run $ cafAnal g
152 let localCAFs = catMaybes $ map (localCAFInfo cafEnv) gs
153 mbpprTrace "localCAFs" (ppr localCAFs) $ return ()
154
155 gs <- run $ mapM (lowerSafeForeignCalls areaMap) gs
156 mapM_ (dumpPlatform platform Opt_D_dump_cmmz_lower "Post lowerSafeForeignCalls") gs
157
158 -- NO MORE GRAPH TRANSFORMATION AFTER HERE -- JUST MAKING INFOTABLES
159 gs <- return $ map (setInfoTableStackMap slotEnv areaMap) gs
160 mapM_ (dumpPlatform platform Opt_D_dump_cmmz_info "after setInfoTableStackMap") gs
161 gs <- return $ map (bundleCAFs cafEnv) gs
162 mapM_ (dumpPlatform platform Opt_D_dump_cmmz_cafs "after bundleCAFs") gs
163 return (localCAFs, gs)
164
165 -- gs :: [ (CAFSet, CmmTop) ]
166 -- localCAFs :: [ (CLabel, CAFSet) ] -- statics filtered out(?)
167
168 where dflags = hsc_dflags hsc_env
169 platform = targetPlatform dflags
170 mbpprTrace x y z = if dopt Opt_D_dump_cmmz dflags then pprTrace x y z else z
171 dump f = dumpWith ppr f
172 dumpPlatform platform = dumpWith (pprPlatform platform)
173 dumpWith pprFun f txt g = do
174 -- ToDo: No easy way of say "dump all the cmmz, *and* split
175 -- them into files." Also, -ddump-cmmz doesn't play nicely
176 -- with -ddump-to-file, since the headers get omitted.
177 dumpIfSet_dyn dflags f txt (pprFun g)
178 when (not (dopt f dflags)) $
179 dumpIfSet_dyn dflags Opt_D_dump_cmmz txt (pprFun g)
180 -- Runs a required transformation/analysis
181 run = runInfiniteFuelIO (hsc_OptFuel hsc_env)
182 -- Runs an optional transformation/analysis (and should
183 -- thus be subject to optimization fuel)
184 runOptimization = runFuelIO (hsc_OptFuel hsc_env)
185
186 -- This probably belongs in CmmBuildInfoTables?
187 -- We're just finishing the job here: once we know what CAFs are defined
188 -- in non-static closures, we can build the SRTs.
189 toTops :: HscEnv -> Map CLabel CAFSet -> (TopSRT, [[CmmTop]])
190 -> [(CAFSet, CmmTop)] -> IO (TopSRT, [[CmmTop]])
191 toTops hsc_env topCAFEnv (topSRT, tops) gs =
192 do let setSRT (topSRT, rst) g =
193 do (topSRT, gs) <- setInfoTableSRT topCAFEnv topSRT g
194 return (topSRT, gs : rst)
195 (topSRT, gs') <- runFuelIO (hsc_OptFuel hsc_env) $ foldM setSRT (topSRT, []) gs
196 return (topSRT, concat gs' : tops)