ghc/compiler/simplCore/SimplPgm.lhs

   1 %
   2 % (c) The AQUA Project, Glasgow University, 1993-1996
   3 %
   4 \section[SimplPgm]{Interface to the simplifier}
   5
   6 \begin{code}
   7 module SimplPgm ( simplifyPgm ) where
   8
   9 #include "HsVersions.h"
  10
  11 import CmdLineOpts      ( opt_D_verbose_core2core, opt_D_dump_simpl_iterations,
  12                           switchIsOn, SimplifierSwitch(..), SwitchResult
  13                         )
  14 import CoreSyn
  15 import Id               ( mkIdEnv, lookupIdEnv, IdEnv
  16                         )
  17 import Maybes           ( catMaybes )
  18 import OccurAnal        ( occurAnalyseBinds )
  19 import PprCore          ( pprCoreBinding ) -- added SOF
  20 import SimplEnv
  21 import SimplMonad
  22 import Simplify         ( simplTopBinds )
  23 import TyVar            ( TyVarEnv )
  24 import UniqSupply       ( thenUs, returnUs, mapUs,
  25                           splitUniqSupply, UniqSM,
  26                           UniqSupply
  27                          )
  28 import Util             ( isIn, isn'tIn, removeDups, trace )
  29 import Outputable
  30
  31 \end{code}
  32
  33 \begin{code}
  34 simplifyPgm :: [CoreBinding]    -- input
  35             -> (SimplifierSwitch->SwitchResult)
  36             -> SimplCount       -- info about how many times
  37                                 -- each transformation has occurred
  38             -> UniqSupply
  39             -> ([CoreBinding],  -- output
  40                  Int,           -- info about how much happened
  41                  SimplCount)    -- accumulated simpl stats
  42
  43 simplifyPgm binds s_sw_chkr simpl_stats us
  44   = --case (splitUniqSupply us)              of { (s1, s2) ->
  45     case (initSmpl us (simpl_pgm 0 1 binds)) of { ((pgm2, it_count, simpl_stats2), _) ->
  46     (pgm2, it_count, combineSimplCounts simpl_stats simpl_stats2) }
  47   where
  48     simpl_switch_is_on  = switchIsOn s_sw_chkr
  49
  50     max_simpl_iterations = getSimplIntSwitch s_sw_chkr MaxSimplifierIterations
  51
  52     simpl_pgm :: Int -> Int -> [CoreBinding] -> SmplM ([CoreBinding], Int, SimplCount)
  53
  54     simpl_pgm n iterations pgm
  55       = -- find out what top-level binders are used,
  56         -- and prepare to unfold all the "simple" bindings
  57         let
  58             tagged_pgm = _scc_ "OccAnal" occurAnalyseBinds pgm simpl_switch_is_on
  59         in
  60               -- do the business
  61         simplTopBinds (nullSimplEnv s_sw_chkr) tagged_pgm `thenSmpl` \ new_pgm ->
  62
  63               -- Quit if we didn't actually do anything; otherwise,
  64               -- try again (if suitable flags)
  65
  66         simplCount                              `thenSmpl` \ r ->
  67         detailedSimplCount                      `thenSmpl` \ dr ->
  68         let
  69             show_status = pprTrace "Simplifer run: " (vcat [
  70                 hcat [ptext SLIT("iteration "),
  71                            int iterations,
  72                            ptext SLIT(" out of "),
  73                            int max_simpl_iterations],
  74                 text (showSimplCount dr),
  75                 if opt_D_dump_simpl_iterations then
  76                         vcat (map (pprCoreBinding) new_pgm)
  77                 else
  78                         empty
  79                 ])
  80         in
  81
  82         (if opt_D_verbose_core2core
  83          || simpl_switch_is_on  ShowSimplifierProgress
  84          then show_status
  85          else id)
  86
  87         (let stop_now = r == n {-nothing happened-}
  88                      || (if iterations >= max_simpl_iterations then
  89                             (if max_simpl_iterations > 1 {-otherwise too boring-} then
  90                                 trace
  91                                 ("NOTE: Simplifier still going after " ++
  92                                   show max_simpl_iterations ++
  93                                   " iterations; bailing out.")
  94                              else id)
  95                             True
  96                          else
  97                             False)
  98         in
  99         if stop_now then
 100             returnSmpl (new_pgm, iterations, dr)
 101         else
 102             simpl_pgm r (iterations + 1) new_pgm
 103         )
 104 \end{code}
 105