diff options
| author | Matthew Pickering <matthewtpickering@gmail.com> | 2021-09-14 15:23:51 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-09-17 09:44:53 -0400 |
| commit | 9eff805a622db499be1fda304e11bb3e6c8d37f0 (patch) | |
| tree | 2e8a604a67cde28ef97dc7bcd87629107560cb19 | |
| parent | 053a5c2c644993274e7779b446170e96e49ab491 (diff) | |
| download | haskell-9eff805a622db499be1fda304e11bb3e6c8d37f0.tar.gz | |
Code Gen: Use strict map rather than lazy map in loop analysis
We were ending up with a big 1GB thunk spike as the `fmap` operation did
not force the key values promptly.
This fixes the high maximum memory consumption when compiling the mmark
package. Compilation is still slow and allocates a lot more than
previous releases.
Related to #19471
| -rw-r--r-- | compiler/GHC/CmmToAsm/CFG.hs | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/compiler/GHC/CmmToAsm/CFG.hs b/compiler/GHC/CmmToAsm/CFG.hs index 21e35afafe..43c0764bad 100644 --- a/compiler/GHC/CmmToAsm/CFG.hs +++ b/compiler/GHC/CmmToAsm/CFG.hs @@ -305,7 +305,9 @@ shortcutWeightMap cuts cfg = applyMapping m (from, Just to) = let updatedMap :: CFG updatedMap - = fmap (shortcutEdge (from,to)) $ + -- Careful here to use a strict mapping function, the derived + -- Functor instance is lazy and leads to a large thunk build-up. #19471/!6523 + = mapMap (shortcutEdge (from,to)) $ (mapDelete from m :: CFG ) --Sometimes we can shortcut multiple blocks like so: -- A -> B -> C -> D -> E => A -> E |