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| author | Matthew Pickering <matthewtpickering@gmail.com> | 2021-09-15 13:06:07 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-09-17 09:44:53 -0400 |
| commit | b041ea7784f036dd7cfc5fae6380db4f3c392ab4 (patch) | |
| tree | 9b8b91e76dfe579cc8424f52c082456c0cf41120 /compiler/GHC | |
| parent | 44e7120dacad683829194b0dbedcfb679d5ffe93 (diff) | |
| download | haskell-b041ea7784f036dd7cfc5fae6380db4f3c392ab4.tar.gz | |
Code Gen: Optimise successors calculation in loop calculation
Before this change, the whole map would be traversed in order to delete
a node from the graph before calculating successors. This is quite
inefficient if the CFG is big, as was the case in the mmark package. A
more efficient alternative is to leave the CFG untouched and then just
delete the node once after the lookups have been performed.
Ticket: #19471
Diffstat (limited to 'compiler/GHC')
| -rw-r--r-- | compiler/GHC/CmmToAsm/CFG.hs | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/compiler/GHC/CmmToAsm/CFG.hs b/compiler/GHC/CmmToAsm/CFG.hs index 5c1f23ceab..d698ae12ca 100644 --- a/compiler/GHC/CmmToAsm/CFG.hs +++ b/compiler/GHC/CmmToAsm/CFG.hs @@ -860,7 +860,7 @@ loopInfo cfg root = LoopInfo { liBackEdges = backEdges = ( edge, setInsert head $ go (setSingleton tail) (setSingleton tail) ) where -- See Note [Determining the loop body] - cfg' = delNode head revCfg + go :: LabelSet -> LabelSet -> LabelSet go found current @@ -870,10 +870,9 @@ loopInfo cfg root = LoopInfo { liBackEdges = backEdges where -- Really predecessors, since we use the reversed cfg. newSuccessors = setFilter (\n -> not $ setMember n found) successors :: LabelSet - successors = setFromList $ concatMap - (getSuccessors cfg') - -- we filter head as it's no longer part of the cfg. - (filter (/= head) $ setElems current) :: LabelSet + successors = setDelete head $ setUnions $ map + (\x -> if x == head then setEmpty else setFromList (getSuccessors revCfg x)) + (setElems current) :: LabelSet backEdges = filter isBackEdge edges loopBodies = map findBody backEdges :: [(Edge, LabelSet)] |