diff options
| -rw-r--r-- | compiler/cmm/CmmContFlowOpt.hs | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/compiler/cmm/CmmContFlowOpt.hs b/compiler/cmm/CmmContFlowOpt.hs index 885e8b54fc..f686aa918b 100644 --- a/compiler/cmm/CmmContFlowOpt.hs +++ b/compiler/cmm/CmmContFlowOpt.hs @@ -12,14 +12,11 @@ where import BlockId import Cmm import CmmUtils -import Digraph import Maybes -import Outputable import Hoopl import Control.Monad import Prelude hiding (succ, unzip, zip) -import qualified Data.IntMap as Map ----------------------------------------------------------------------------- -- @@ -106,16 +103,30 @@ blockConcat g@CmmGraph { g_entry = entry_id } , shouldConcatWith b' blk' = (mapInsert bid (splice head blk') blocks, shortcut_map) + -- calls: if we can shortcut the continuation label, then + -- we must *also* remember to substitute for the label in the + -- code, because we will push it somewhere. | Just b' <- callContinuation_maybe last , Just blk' <- mapLookup b' blocks , Just dest <- canShortcut blk' = (blocks, mapInsert b' dest shortcut_map) -- replaceLabels will substitute dest for b' everywhere, later - | otherwise = unchanged + -- non-calls: see if we can shortcut any of the successors. + | Nothing <- callContinuation_maybe last + = ( mapInsert bid (blockJoinTail head shortcut_last) blocks + , shortcut_map ) + + | otherwise + = (blocks, shortcut_map) where (head, last) = blockSplitTail block bid = entryLabel block + shortcut_last = mapSuccessors shortcut last + shortcut l = + case mapLookup l blocks of + Just b | Just dest <- canShortcut b -> dest + _otherwise -> l shouldConcatWith b block | num_preds b == 1 = True -- only one predecessor: go for it |