fitting predicates never get used with Unbounded PageWidth

[sjakobi]

Since ca70266 we never use a FittingPredicate with Unbounded – the PageWidth is always an AvailablePerLine n r.

To make the code clearer, and potentially help performance, the page width used in the fitting predicates should have only a single constructor then.

Note that, as pointed out in #142, we only actually use the "page width" Int, but not the "ribbon width" Double from AvailablePerLine.

[sjakobi]

Relevant -O1 Core for layoutSmart:

Details

Rec {
-- RHS size: {terms: 73, types: 45, coercions: 0, joins: 0/0}
$wfits1 [InlPrag=NOUSERINLINE[2], Occ=LoopBreaker]
  :: forall ann1 ann2.
     PageWidth -> Int -> Int# -> SimpleDocStream ann2 -> Bool
[GblId,
 Arity=4,
 Caf=NoCafRefs,
 Str=<L,1*U><L,1*U(U)><L,U><L,1*U>,
 Unf=OtherCon []]
$wfits1
  = \ (@ ann_smS1)
      (@ ann1_smS2)
      (w_smS3 :: PageWidth)
      (w1_smS4 :: Int)
      (ww_smS9 :: Int#)
      (w2_smS6 :: SimpleDocStream ann1_smS2) ->
      case <# ww_smS9 0# of {
        __DEFAULT ->
          case w2_smS6 of {
            SFail -> False;
            SEmpty -> True;
            SChar ds_dgcF x_a5VB ->
              $wfits1
                @ ann_smS1 @ ann1_smS2 w_smS3 w1_smS4 (-# ww_smS9 1#) x_a5VB;
            SText dt_dheX _t_a5VG x_a5VH ->
              $wfits1
                @ ann_smS1 @ ann1_smS2 w_smS3 w1_smS4 (-# ww_smS9 dt_dheX) x_a5VH;
            SLine dt_dheY x_a5VL ->
              case w1_smS4 of wild1_Xi62 { I# x1_Xi66 ->
              case <# x1_Xi66 dt_dheY of {
                __DEFAULT -> True;
                1# ->
                  case w_smS3 of wild2_X3V {
                    AvailablePerLine cpl_a5VM ds_dgbW ->
                      case cpl_a5VM of { I# x2_ahBF ->
                      $wfits1
                        @ ann_smS1
                        @ ann1_smS2
                        wild2_X3V
                        wild1_Xi62
                        (-# x2_ahBF dt_dheY)
                        x_a5VL
                      };
                    Unbounded -> True
                  }
              }
              };
            SAnnPush ds_dgcG x_a5VQ ->
              $wfits1 @ ann_smS1 @ ann1_smS2 w_smS3 w1_smS4 ww_smS9 x_a5VQ;
            SAnnPop x_a5VU ->
              $wfits1 @ ann_smS1 @ ann1_smS2 w_smS3 w1_smS4 ww_smS9 x_a5VU
          };
        1# -> False
      }
end Rec }

-- RHS size: {terms: 14, types: 13, coercions: 0, joins: 0/0}
layoutSmart_fits [InlPrag=NOUSERINLINE[2]]
  :: forall ann1 ann2.
     PageWidth -> Int -> Int -> SimpleDocStream ann2 -> Bool
[GblId,
 Arity=4,
 Caf=NoCafRefs,
 Str=<L,1*U><L,1*U(U)><S,1*U(U)><L,1*U>,
 Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True,
         WorkFree=True, Expandable=True,
         Guidance=ALWAYS_IF(arity=4,unsat_ok=True,boring_ok=False)}]
layoutSmart_fits
  = \ (@ ann_smS1)
      (@ ann1_smS2)
      (w_smS3 :: PageWidth)
      (w1_smS4 :: Int)
      (w2_smS5 :: Int)
      (w3_smS6 :: SimpleDocStream ann1_smS2) ->
      case w2_smS5 of { I# ww1_smS9 ->
      $wfits1 @ ann_smS1 @ ann1_smS2 w_smS3 w1_smS4 ww1_smS9 w3_smS6
      }

-- RHS size: {terms: 3, types: 5, coercions: 3, joins: 0/0}
layoutSmart
  :: forall ann. LayoutOptions -> Doc ann -> SimpleDocStream ann
[GblId,
 Arity=2,
 Caf=NoCafRefs,
 Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
         WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 20 60}]
layoutSmart
  = \ (@ ann_adY3) ->
      layoutWadlerLeijen
        @ ann_adY3 ((layoutSmart_fits @ ann_adY3 @ ann_adY3) `cast` <Co:3>)

With -O2 GHC creates an additional fits worker that takes only the "page width" Int#:

Details

Rec {
-- RHS size: {terms: 68, types: 39, coercions: 0, joins: 0/0}
layoutSmart_$s$wfits [Occ=LoopBreaker]
  :: forall ann1 ann2.
     SimpleDocStream ann1 -> Int# -> Int# -> Int# -> Double -> Bool
[GblId,
 Arity=5,
 Caf=NoCafRefs,
 Str=<L,1*U><L,U><L,U><L,U><L,A>,
 Unf=OtherCon []]
layoutSmart_$s$wfits
  = \ (@ ann_smS6)
      (@ ann1_smS5)
      (sc_spYB :: SimpleDocStream ann_smS6)
      (sc1_spYA :: Int#)
      (sc2_spYz :: Int#)
      (sc3_spYx :: Int#)
      (sc4_spYy :: Double) ->
      case <# sc1_spYA 0# of {
        __DEFAULT ->
          case sc_spYB of {
            SFail -> False;
            SEmpty -> True;
            SChar ds_dgcJ x_a5VE ->
              layoutSmart_$s$wfits
                @ ann_smS6
                @ ann1_smS5
                x_a5VE
                (-# sc1_spYA 1#)
                sc2_spYz
                sc3_spYx
                sc4_spYy;
            SText dt_dhf1 _t_a5VJ x_a5VK ->
              layoutSmart_$s$wfits
                @ ann_smS6
                @ ann1_smS5
                x_a5VK
                (-# sc1_spYA dt_dhf1)
                sc2_spYz
                sc3_spYx
                sc4_spYy;
            SLine dt_dhf2 x_a5VO ->
              case <# sc2_spYz dt_dhf2 of {
                __DEFAULT -> True;
                1# ->
                  layoutSmart_$s$wfits
                    @ ann_smS6
                    @ ann1_smS5
                    x_a5VO
                    (-# sc3_spYx dt_dhf2)
                    sc2_spYz
                    sc3_spYx
                    sc4_spYy
              };
            SAnnPush ds_dgcK x_a5VT ->
              layoutSmart_$s$wfits
                @ ann_smS6 @ ann1_smS5 x_a5VT sc1_spYA sc2_spYz sc3_spYx sc4_spYy;
            SAnnPop x_a5VX ->
              layoutSmart_$s$wfits
                @ ann_smS6 @ ann1_smS5 x_a5VX sc1_spYA sc2_spYz sc3_spYx sc4_spYy
          };
        1# -> False
      }
end Rec }

Rec {
-- RHS size: {terms: 74, types: 45, coercions: 0, joins: 0/0}
$wfits1 [InlPrag=NOUSERINLINE[2], Occ=LoopBreaker]
  :: forall ann1 ann2.
     PageWidth -> Int -> Int# -> SimpleDocStream ann2 -> Bool
[GblId,
 Arity=4,
 Caf=NoCafRefs,
 Str=<L,1*U><L,1*U(U)><L,U><L,1*U>,
 Unf=OtherCon []]
$wfits1
  = \ (@ ann_smS5)
      (@ ann1_smS6)
      (w_smS7 :: PageWidth)
      (w1_smS8 :: Int)
      (ww_smSd :: Int#)
      (w2_smSa :: SimpleDocStream ann1_smS6) ->
      case <# ww_smSd 0# of {
        __DEFAULT ->
          case w2_smSa of {
            SFail -> False;
            SEmpty -> True;
            SChar ds_dgcJ x_a5VE ->
              $wfits1
                @ ann_smS5 @ ann1_smS6 w_smS7 w1_smS8 (-# ww_smSd 1#) x_a5VE;
            SText dt_dhf1 _t_a5VJ x_a5VK ->
              $wfits1
                @ ann_smS5 @ ann1_smS6 w_smS7 w1_smS8 (-# ww_smSd dt_dhf1) x_a5VK;
            SLine dt_dhf2 x_a5VO ->
              case w1_smS8 of { I# x1_Xi6a ->
              case <# x1_Xi6a dt_dhf2 of {
                __DEFAULT -> True;
                1# ->
                  case w_smS7 of {
                    AvailablePerLine cpl_a5VP ds_dgc0 ->
                      case cpl_a5VP of { I# x2_ahBJ ->
                      layoutSmart_$s$wfits
                        @ ann1_smS6
                        @ ann_smS5
                        x_a5VO
                        (-# x2_ahBJ dt_dhf2)
                        x1_Xi6a
                        x2_ahBJ
                        ds_dgc0
                      };
                    Unbounded -> True
                  }
              }
              };
            SAnnPush ds_dgcK x_a5VT ->
              $wfits1 @ ann_smS5 @ ann1_smS6 w_smS7 w1_smS8 ww_smSd x_a5VT;
            SAnnPop x_a5VX ->
              $wfits1 @ ann_smS5 @ ann1_smS6 w_smS7 w1_smS8 ww_smSd x_a5VX
          };
        1# -> False
      }
end Rec }

-- RHS size: {terms: 14, types: 13, coercions: 0, joins: 0/0}
layoutSmart_fits [InlPrag=NOUSERINLINE[2]]
  :: forall ann1 ann2.
     PageWidth -> Int -> Int -> SimpleDocStream ann2 -> Bool
[GblId,
 Arity=4,
 Caf=NoCafRefs,
 Str=<L,1*U><L,1*U(U)><S,1*U(U)><L,1*U>,
 Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True,
         WorkFree=True, Expandable=True,
         Guidance=ALWAYS_IF(arity=4,unsat_ok=True,boring_ok=False)}]
layoutSmart_fits
  = \ (@ ann_smS5)
      (@ ann1_smS6)
      (w_smS7 :: PageWidth)
      (w1_smS8 :: Int)
      (w2_smS9 :: Int)
      (w3_smSa :: SimpleDocStream ann1_smS6) ->
      case w2_smS9 of { I# ww1_smSd ->
      $wfits1 @ ann_smS5 @ ann1_smS6 w_smS7 w1_smS8 ww1_smSd w3_smSa
      }

-- RHS size: {terms: 3, types: 5, coercions: 3, joins: 0/0}
layoutSmart
  :: forall ann. LayoutOptions -> Doc ann -> SimpleDocStream ann
[GblId,
 Arity=2,
 Caf=NoCafRefs,
 Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
         WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 20 60}]
layoutSmart
  = \ (@ ann_adY7) ->
      layoutWadlerLeijen
        @ ann_adY7 ((layoutSmart_fits @ ann_adY7 @ ann_adY7) `cast` <Co:3>)

Which optimization does that BTW? SpecConstr? CPR?