diff options
Diffstat (limited to 'compiler/cmm/CmmSpillReload.hs')
| -rw-r--r-- | compiler/cmm/CmmSpillReload.hs | 41 |
1 files changed, 32 insertions, 9 deletions
diff --git a/compiler/cmm/CmmSpillReload.hs b/compiler/cmm/CmmSpillReload.hs index bef608036b..3142e8e62d 100644 --- a/compiler/cmm/CmmSpillReload.hs +++ b/compiler/cmm/CmmSpillReload.hs @@ -107,15 +107,7 @@ middleDualLiveness live m@(Reload regs) = where live' = DualLive { on_stack = on_stack live `plusRegSet` regs , in_regs = in_regs live `minusRegSet` regs } -middleDualLiveness live (NotSpillOrReload m) = middle m live - where middle (MidNop) = id - middle (MidComment {}) = id - middle (MidAssign (CmmLocal reg') expr) = changeRegs (gen expr . kill reg') - middle (MidAssign (CmmGlobal _) expr) = changeRegs (gen expr) - middle (MidStore addr rval) = changeRegs (gen addr . gen rval) - middle (MidUnsafeCall _ ress args) = changeRegs (gen args . kill ress) - middle (CopyIn _ formals _) = changeRegs (kill formals) - middle (CopyOut _ formals) = changeRegs (gen formals) +middleDualLiveness live (NotSpillOrReload m) = changeRegs (middleLiveness m) live lastDualLiveness :: (BlockId -> DualLive) -> Last -> DualLive lastDualLiveness env l = last l @@ -196,6 +188,37 @@ show_regs :: String -> RegSet -> Middle show_regs s regs = MidComment $ mkFastString $ showSDoc $ ppr_regs s regs +---------------------------------------------------------------- +--- sinking reloads + +{- + +-- The idea is to compute at each point the set of registers such that +-- on every path to the point, the register is defined by a Reload +-- instruction. Then, if a use appears at such a point, we can safely +-- insert a Reload right before the use. Finally, we can eliminate +-- the early reloads along with other dead assignments. + +data AvailRegs = UniverseMinus RegSet + | AvailRegs RegSet + +availRegsLattice :: DataflowLattice AvailRegs +availRegsLattice = + DataflowLattice "register gotten from reloads" empty add False + where empty = DualLive emptyRegSet emptyRegSet + -- | compute in the Tx monad to track whether anything has changed + add new old = do stack <- add1 (on_stack new) (on_stack old) + regs <- add1 (in_regs new) (in_regs old) + return $ DualLive stack regs + add1 = fact_add_to liveLattice + + + + +-} + + + --------------------- -- prettyprinting |