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authorSimon Peyton Jones <simonpj@microsoft.com>2021-04-20 13:56:52 +0100
committerMarge Bot <ben+marge-bot@smart-cactus.org>2021-04-20 21:33:09 -0400
commitb7980b5d94d34943b3965cf79c4e610f00a9ee7d (patch)
tree053655e4603523d7571e9532a79392a3a5fa74c5
parentfdbead70d5920c35b6fd96b723f00aaa95763ae2 (diff)
downloadhaskell-b7980b5d94d34943b3965cf79c4e610f00a9ee7d.tar.gz
Fix occAnalApp
In OccurAnal the function occAnalApp was failing to reset occ_encl to OccVanilla. This omission sometimes resulted in over-pessimistic occurrence information. I tripped over this when analysing eta-expansions. Compile times in perf/compiler fell slightly (no increases) PmSeriesG(normal) ghc/alloc 50738104.0 50580440.0 -0.3% PmSeriesS(normal) ghc/alloc 64045284.0 63739384.0 -0.5% PmSeriesT(normal) ghc/alloc 94430324.0 93800688.0 -0.7% PmSeriesV(normal) ghc/alloc 63051056.0 62758240.0 -0.5% T10547(normal) ghc/alloc 29322840.0 29307784.0 -0.1% T10858(normal) ghc/alloc 191988716.0 189801744.0 -1.1% T11195(normal) ghc/alloc 282654016.0 281839440.0 -0.3% T11276(normal) ghc/alloc 142994648.0 142338688.0 -0.5% T11303b(normal) ghc/alloc 46435532.0 46343376.0 -0.2% T11374(normal) ghc/alloc 256866536.0 255653056.0 -0.5% T11822(normal) ghc/alloc 140210356.0 138935296.0 -0.9% T12234(optasm) ghc/alloc 60753880.0 60720648.0 -0.1% T14052(ghci) ghc/alloc 2235105796.0 2230906584.0 -0.2% T17096(normal) ghc/alloc 297725396.0 296237112.0 -0.5% T17836(normal) ghc/alloc 1127785292.0 1125316160.0 -0.2% T17836b(normal) ghc/alloc 54761928.0 54637592.0 -0.2% T17977(normal) ghc/alloc 47529464.0 47397048.0 -0.3% T17977b(normal) ghc/alloc 42906972.0 42809824.0 -0.2% T18478(normal) ghc/alloc 777385708.0 774219280.0 -0.4% T18698a(normal) ghc/alloc 415097664.0 409009120.0 -1.5% GOOD T18698b(normal) ghc/alloc 500082104.0 493124016.0 -1.4% GOOD T18923(normal) ghc/alloc 72252364.0 72216016.0 -0.1% T1969(normal) ghc/alloc 811581860.0 804883136.0 -0.8% T5837(normal) ghc/alloc 37688048.0 37666288.0 -0.1% Nice! Metric Decrease: T18698a T18698b
-rw-r--r--compiler/GHC/Core/Opt/OccurAnal.hs18
1 files changed, 13 insertions, 5 deletions
diff --git a/compiler/GHC/Core/Opt/OccurAnal.hs b/compiler/GHC/Core/Opt/OccurAnal.hs
index 83c44dcec2..7efcba8cd8 100644
--- a/compiler/GHC/Core/Opt/OccurAnal.hs
+++ b/compiler/GHC/Core/Opt/OccurAnal.hs
@@ -2124,10 +2124,22 @@ occAnalApp env (fun, args, ticks)
-- often leaves behind beta redexs like
-- (\x y -> e) a1 a2
-- Here we would like to mark x,y as one-shot, and treat the whole
- -- thing much like a let. We do this by pushing some True items
+ -- thing much like a let. We do this by pushing some OneShotLam items
-- onto the context stack.
!(args_uds, args') = occAnalArgs env args []
+addAppCtxt :: OccEnv -> [Arg CoreBndr] -> OccEnv
+addAppCtxt env@(OccEnv { occ_one_shots = ctxt }) args
+ | n_val_args > 0
+ = env { occ_one_shots = replicate n_val_args OneShotLam ++ ctxt
+ , occ_encl = OccVanilla }
+ -- OccVanilla: the function part of the application
+ -- is no longer on OccRhs or OccScrut
+ | otherwise
+ = env
+ where
+ n_val_args = valArgCount args
+
{-
Note [Sources of one-shot information]
@@ -2407,10 +2419,6 @@ markJoinOneShots mb_join_arity bndrs
b' | isId b = setOneShotLambda b
| otherwise = b
-addAppCtxt :: OccEnv -> [Arg CoreBndr] -> OccEnv
-addAppCtxt env@(OccEnv { occ_one_shots = ctxt }) args
- = env { occ_one_shots = replicate (valArgCount args) OneShotLam ++ ctxt }
-
--------------------
transClosureFV :: VarEnv VarSet -> VarEnv VarSet
-- If (f,g), (g,h) are in the input, then (f,h) is in the output