Vectorise.hs 13.8 KB
Newer Older
1 2 3 4 5 6
-- Main entry point to the vectoriser.  It is invoked iff the option '-fvectorise' is passed.
--
-- This module provides the function 'vectorise', which vectorises an entire (desugared) module.
-- It vectorises all type declarations and value bindings.  It also processes all VECTORISE pragmas
-- (aka vectorisation declarations), which can lead to the vectorisation of imported data types
-- and the enrichment of imported functions with vectorised versions.
7

8
module Vectorise ( vectorise )
9 10
where

11 12 13
import Vectorise.Type.Env
import Vectorise.Type.Type
import Vectorise.Convert
14
import Vectorise.Utils.Hoisting
15
import Vectorise.Exp
16
import Vectorise.Vect
17
import Vectorise.Env
18
import Vectorise.Monad
19

20
import HscTypes hiding      ( MonadThings(..) )
21
import CoreUnfold           ( mkInlineUnfolding )
22
import CoreFVs
23 24
import PprCore
import CoreSyn
Ian Lynagh's avatar
Ian Lynagh committed
25
import CoreMonad            ( CoreM, getHscEnv )
26
import Type
rl@cse.unsw.edu.au's avatar
rl@cse.unsw.edu.au committed
27
import Id
28
import DynFlags
29
import BasicTypes           ( isStrongLoopBreaker )
30
import Outputable
31
import Util                 ( zipLazy )
32 33
import MonadUtils

34
import Control.Monad
35
import Data.Maybe
36 37


38
-- |Vectorise a single module.
39 40 41 42 43 44
--
vectorise :: ModGuts -> CoreM ModGuts
vectorise guts
 = do { hsc_env <- getHscEnv
      ; liftIO $ vectoriseIO hsc_env guts
      }
45

46
-- Vectorise a single monad, given the dynamic compiler flags and HscEnv.
47 48 49 50 51
--
vectoriseIO :: HscEnv -> ModGuts -> IO ModGuts
vectoriseIO hsc_env guts
 = do {   -- Get information about currently loaded external packages.
      ; eps <- hscEPS hsc_env
52

53 54
          -- Combine vectorisation info from the current module, and external ones.
      ; let info = hptVectInfo hsc_env `plusVectInfo` eps_vect_info eps
55

56 57 58 59
          -- Run the main VM computation.
      ; Just (info', guts') <- initV hsc_env guts info (vectModule guts)
      ; return (guts' { mg_vect_info = info' })
      }
60

61
-- Vectorise a single module, in the VM monad.
62
--
rl@cse.unsw.edu.au's avatar
rl@cse.unsw.edu.au committed
63
vectModule :: ModGuts -> VM ModGuts
64
vectModule guts@(ModGuts { mg_tcs        = tycons
65 66
                         , mg_clss       = classes
                         , mg_insts      = insts
67 68 69
                         , mg_binds      = binds
                         , mg_fam_insts  = fam_insts
                         , mg_vect_decls = vect_decls
70 71 72 73
                         })
 = do { dumpOptVt Opt_D_dump_vt_trace "Before vectorisation" $ 
          pprCoreBindings binds
 
74 75 76 77 78 79
          -- Vectorise the type environment.  This will add vectorised
          -- type constructors, their representaions, and the
          -- conrresponding data constructors.  Moreover, we produce
          -- bindings for dfuns and family instances of the classes
          -- and type families used in the DPH library to represent
          -- array types.
80 81
      ; (new_tycons, new_fam_insts, tc_binds) <- vectTypeEnv tycons [vd
                                                                    | vd@(VectType _ _ _) <- vect_decls]
82

83 84 85 86 87 88
      ; let new_classes = []  -- !!!FIXME
            new_insts   = []
            -- !!!we need to compute an extended 'mg_inst_env' as well!!!

          -- Family instance environment for /all/ home-package modules including those instances
          -- generated by 'vectTypeEnv'.
89
      ; (_, fam_inst_env) <- readGEnv global_fam_inst_env
Ian Lynagh's avatar
Ian Lynagh committed
90

91 92 93
          -- Vectorise all the top level bindings and VECTORISE declarations on imported identifiers
      ; binds_top <- mapM vectTopBind binds
      ; binds_imp <- mapM vectImpBind [imp_id | Vect imp_id _ <- vect_decls, isGlobalId imp_id]
rl@cse.unsw.edu.au's avatar
rl@cse.unsw.edu.au committed
94

95 96 97
      ; return $ guts { mg_tcs          = tycons ++ new_tycons
                      , mg_clss         = classes ++ new_classes
                      , mg_insts        = insts ++ new_insts
98
                      , mg_binds        = Rec tc_binds : (binds_top ++ binds_imp)
99 100 101 102
                      , mg_fam_inst_env = fam_inst_env
                      , mg_fam_insts    = fam_insts ++ new_fam_insts
                      }
      }
103

104
-- Try to vectorise a top-level binding.  If it doesn't vectorise then return it unharmed.
105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143
--
-- For example, for the binding 
--
-- @  
--    foo :: Int -> Int
--    foo = \x -> x + x
-- @
--
-- we get
-- @
--    foo  :: Int -> Int
--    foo  = \x -> vfoo $: x                  
--
--    v_foo :: Closure void vfoo lfoo
--    v_foo = closure vfoo lfoo void        
--
--    vfoo :: Void -> Int -> Int
--    vfoo = ...
--
--    lfoo :: PData Void -> PData Int -> PData Int
--    lfoo = ...
-- @ 
--
-- @vfoo@ is the "vectorised", or scalar, version that does the same as the original
-- function foo, but takes an explicit environment.
--
-- @lfoo@ is the "lifted" version that works on arrays.
--
-- @v_foo@ combines both of these into a `Closure` that also contains the
-- environment.
--
-- The original binding @foo@ is rewritten to call the vectorised version
-- present in the closure.
--
-- Vectorisation may be surpressed by annotating a binding with a 'NOVECTORISE' pragma.  If this
-- pragma is used in a group of mutually recursive bindings, either all or no binding must have
-- the pragma.  If only some bindings are annotated, a fatal error is being raised.
-- FIXME: Once we support partial vectorisation, we may be able to vectorise parts of a group, or
--   we may emit a warning and refrain from vectorising the entire group.
144
--
145
vectTopBind :: CoreBind -> VM CoreBind
146
vectTopBind b@(NonRec var expr)
147 148 149 150 151 152 153 154 155 156 157 158 159 160
  = unlessNoVectDecl $
      do {   -- Vectorise the right-hand side, create an appropriate top-level binding and add it
             -- to the vectorisation map.
         ; (inline, isScalar, expr') <- vectTopRhs [] var expr
         ; var' <- vectTopBinder var inline expr'
         ; when isScalar $ 
             addGlobalScalar var
 
             -- We replace the original top-level binding by a value projected from the vectorised
             -- closure and add any newly created hoisted top-level bindings.
         ; cexpr <- tryConvert var var' expr
         ; hs <- takeHoisted
         ; return . Rec $ (var, cexpr) : (var', expr') : hs
         }
161 162 163 164
     `orElseErrV`
     do { emitVt "  Could NOT vectorise top-level binding" $ ppr var
        ; return b
        }
165 166 167 168 169 170 171
  where
    unlessNoVectDecl vectorise
      = do { hasNoVectDecl <- noVectDecl var
           ; when hasNoVectDecl $
               traceVt "NOVECTORISE" $ ppr var
           ; if hasNoVectDecl then return b else vectorise
           }
172
vectTopBind b@(Rec bs)
173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200
  = unlessSomeNoVectDecl $
      do { (vars', _, exprs', hs) <- fixV $ 
             \ ~(_, inlines, rhss, _) ->
               do {   -- Vectorise the right-hand sides, create an appropriate top-level bindings
                      -- and add them to the vectorisation map.
                  ; vars' <- sequence [vectTopBinder var inline rhs
                                      | (var, ~(inline, rhs)) <- zipLazy vars (zip inlines rhss)]
                  ; (inlines, areScalars, exprs') <- mapAndUnzip3M (uncurry $ vectTopRhs vars) bs
                  ; hs <- takeHoisted
                  ; if and areScalars
                    then      -- (1) Entire recursive group is scalar
                              --      => add all variables to the global set of scalars
                         do { mapM_ addGlobalScalar vars
                            ; return (vars', inlines, exprs', hs)
                            }
                    else      -- (2) At least one binding is not scalar
                              --     => vectorise again with empty set of local scalars
                         do { (inlines, _, exprs') <- mapAndUnzip3M (uncurry $ vectTopRhs []) bs
                            ; hs <- takeHoisted
                            ; return (vars', inlines, exprs', hs)
                            }
                  }
                       
             -- Replace the original top-level bindings by a values projected from the vectorised
             -- closures and add any newly created hoisted top-level bindings to the group.
         ; cexprs <- sequence $ zipWith3 tryConvert vars vars' exprs
         ; return . Rec $ zip vars cexprs ++ zip vars' exprs' ++ hs
         }
201
     `orElseErrV`
202 203 204 205 206 207 208 209 210 211 212 213 214 215 216
       return b    
  where
    (vars, exprs) = unzip bs

    unlessSomeNoVectDecl vectorise
      = do { hasNoVectDecls <- mapM noVectDecl vars
           ; when (and hasNoVectDecls) $
               traceVt "NOVECTORISE" $ ppr vars
           ; if and hasNoVectDecls 
             then return b                              -- all bindings have 'NOVECTORISE'
             else if or hasNoVectDecls 
             then cantVectorise noVectoriseErr (ppr b)  -- some (but not all) have 'NOVECTORISE'
             else vectorise                             -- no binding has a 'NOVECTORISE' decl
           }
    noVectoriseErr = "NOVECTORISE must be used on all or no bindings of a recursive group"
217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235

-- Add a vectorised binding to an imported top-level variable that has a VECTORISE [SCALAR] pragma
-- in this module.
--
vectImpBind :: Id -> VM CoreBind
vectImpBind var
  = do {   -- Vectorise the right-hand side, create an appropriate top-level binding and add it
           -- to the vectorisation map.  For the non-lifted version, we refer to the original
           -- definition — i.e., 'Var var'.
       ; (inline, isScalar, expr') <- vectTopRhs [] var (Var var)
       ; var' <- vectTopBinder var inline expr'
       ; when isScalar $ 
           addGlobalScalar var

           -- We add any newly created hoisted top-level bindings.
       ; hs <- takeHoisted
       ; return . Rec $ (var', expr') : hs
       }

236 237 238 239
-- | Make the vectorised version of this top level binder, and add the mapping
--   between it and the original to the state. For some binder @foo@ the vectorised
--   version is @$v_foo@
--
240 241
--   NOTE: 'vectTopBinder' *MUST* be lazy in inline and expr because of how it is
--   used inside of 'fixV' in 'vectTopBind'.
242 243 244 245 246
--
vectTopBinder :: Var      -- ^ Name of the binding.
              -> Inline   -- ^ Whether it should be inlined, used to annotate it.
              -> CoreExpr -- ^ RHS of binding, used to set the 'Unfolding' of the returned 'Var'.
              -> VM Var   -- ^ Name of the vectorised binding.
247
vectTopBinder var inline expr
248 249 250 251
 = do {   -- Vectorise the type attached to the var.
      ; vty  <- vectType (idType var)
      
          -- If there is a vectorisation declartion for this binding, make sure that its type
252
          -- matches
253 254
      ; vectDecl <- lookupVectDecl var
      ; case vectDecl of
255
          Nothing             -> return ()
256
          Just (vdty, _) 
257
            | eqType vty vdty -> return ()
258
            | otherwise       -> 
259 260 261 262 263 264 265
              cantVectorise ("Type mismatch in vectorisation pragma for " ++ show var) $
                (text "Expected type" <+> ppr vty)
                $$
                (text "Inferred type" <+> ppr vdty)

          -- Make the vectorised version of binding's name, and set the unfolding used for inlining
      ; var' <- liftM (`setIdUnfoldingLazily` unfolding) 
266
                $  mkVectId var vty
267 268 269 270 271 272

          -- Add the mapping between the plain and vectorised name to the state.
      ; defGlobalVar var var'

      ; return var'
    }
273 274
  where
    unfolding = case inline of
275
                  Inline arity -> mkInlineUnfolding (Just arity) expr
276
                  DontInline   -> noUnfolding
Ian Lynagh's avatar
Ian Lynagh committed
277

278
-- | Vectorise the RHS of a top-level binding, in an empty local environment.
279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297
--
-- We need to distinguish three cases:
--
-- (1) We have a (non-scalar) vectorisation declaration for the variable (which explicitly provides
--     vectorised code implemented by the user)
--     => no automatic vectorisation & instead use the user-supplied code
-- 
-- (2) We have a scalar vectorisation declaration for the variable
--     => generate vectorised code that uses a scalar 'map'/'zipWith' to lift the computation
-- 
-- (3) There is no vectorisation declaration for the variable
--     => perform automatic vectorisation of the RHS
--
vectTopRhs :: [Var]           -- ^ Names of all functions in the rec block
           -> Var             -- ^ Name of the binding.
           -> CoreExpr        -- ^ Body of the binding.
           -> VM ( Inline     -- (1) inline specification for the binding
                 , Bool       -- (2) whether the right-hand side is a scalar computation
                 , CoreExpr)  -- (3) the vectorised right-hand side
298
vectTopRhs recFs var expr
299
  = closedV
300
  $ do { globalScalar <- isGlobalScalar var
301
       ; vectDecl     <- lookupVectDecl var
302 303 304

       ; traceVt ("vectTopRhs of " ++ show var ++ info globalScalar vectDecl) $ ppr expr

305 306 307 308 309
       ; rhs globalScalar vectDecl
       }
  where
    rhs _globalScalar (Just (_, expr'))               -- Case (1)
      = return (inlineMe, False, expr')
310 311 312 313 314
    rhs True          Nothing                         -- Case (2)
      = do { expr' <- vectScalarFun True recFs expr
           ; return (inlineMe, True, vectorised expr')
           }
    rhs False         Nothing                         -- Case (3)
315
      = do { let fvs = freeVars expr
316 317 318
           ; (inline, isScalar, vexpr) 
               <- inBind var $
                    vectPolyExpr (isStrongLoopBreaker $ idOccInfo var) recFs fvs
319 320
           ; return (inline, isScalar, vectorised vexpr)
           }
321 322 323 324
    
    info True  _                          = " [VECTORISE SCALAR]"
    info False vectDecl | isJust vectDecl = " [VECTORISE]"
                        | otherwise       = " (no pragma)"
325

326 327
-- |Project out the vectorised version of a binding from some closure,
-- or return the original body if that doesn't work or the binding is scalar. 
328 329 330 331 332
--
tryConvert :: Var       -- ^ Name of the original binding (eg @foo@)
           -> Var       -- ^ Name of vectorised version of binding (eg @$vfoo@)
           -> CoreExpr  -- ^ The original body of the binding.
           -> VM CoreExpr
333
tryConvert var vect_var rhs
334 335 336 337 338
  = do { globalScalar <- isGlobalScalar var
       ; if globalScalar
         then
           return rhs
         else
339 340 341 342 343
           fromVect (idType var) (Var vect_var) 
           `orElseErrV` 
           do { emitVt "  Could NOT call vectorised from original version" $ ppr var
              ; return rhs
              }
344
       }