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| author | Sebastian Graf <sebastian.graf@kit.edu> | 2022-03-12 15:22:13 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2022-03-14 15:09:01 -0400 |
| commit | 8ff32124c8cd37050f3dc7cbb32b8d41711ebcaf (patch) | |
| tree | 1f6649ef979b6024c2bf45cd5849ed6c942e1d8f /compiler/ghc.cabal.in | |
| parent | 8eadea670adb5de49ddba7e23d04ec8242ba76a3 (diff) | |
| download | haskell-8ff32124c8cd37050f3dc7cbb32b8d41711ebcaf.tar.gz | |
DmdAnal: Don't unbox recursive data types (#11545)
As `Note [Demand analysis for recursive data constructors]` describes, we now
refrain from unboxing recursive data type arguments, for two reasons:
1. Relating to run/alloc perf: Similar to
`Note [CPR for recursive data constructors]`, it seldomly improves run/alloc
performance if we just unbox a finite number of layers of a potentially huge
data structure.
2. Relating to ghc/alloc perf: Inductive definitions on single-product
recursive data types like the one in T11545 will (diverge, and) have very
deep demand signatures before any other abortion mechanism in Demand
analysis is triggered. That leads to great and unnecessary churn on Demand
analysis when ultimately we will never make use of any nested strictness
information anyway.
Conclusion: Discard nested demand and boxity information on such recursive types
with the help of `Note [Detecting recursive data constructors]`.
I also implemented `GHC.Types.Unique.MemoFun.memoiseUniqueFun` in order to avoid
the overhead of repeated calls to `GHC.Core.Opt.WorkWrap.Utils.isRecDataCon`.
It's nice and simple and guards against some smaller regressions in T9233 and
T16577.
ghc/alloc performance-wise, this patch is a very clear win:
Test Metric value New value Change
---------------------------------------------------------------------------------------
LargeRecord(normal) ghc/alloc 6,141,071,720 6,099,871,216 -0.7%
MultiLayerModulesTH_OneShot(normal) ghc/alloc 2,740,973,040 2,705,146,640 -1.3%
T11545(normal) ghc/alloc 945,475,492 85,768,928 -90.9% GOOD
T13056(optasm) ghc/alloc 370,245,880 326,980,632 -11.7% GOOD
T18304(normal) ghc/alloc 90,933,944 76,998,064 -15.3% GOOD
T9872a(normal) ghc/alloc 1,800,576,840 1,792,348,760 -0.5%
T9872b(normal) ghc/alloc 2,086,492,432 2,073,991,848 -0.6%
T9872c(normal) ghc/alloc 1,750,491,240 1,737,797,832 -0.7%
TcPlugin_RewritePerf(normal) ghc/alloc 2,286,813,400 2,270,957,896 -0.7%
geo. mean -2.9%
No noteworthy change in run/alloc either.
NoFib results show slight wins, too:
--------------------------------------------------------------------------------
Program Allocs Instrs
--------------------------------------------------------------------------------
constraints -1.9% -1.4%
fasta -3.6% -2.7%
reverse-complem -0.3% -0.9%
treejoin -0.0% -0.3%
--------------------------------------------------------------------------------
Min -3.6% -2.7%
Max +0.1% +0.1%
Geometric Mean -0.1% -0.1%
Metric Decrease:
T11545
T13056
T18304
Diffstat (limited to 'compiler/ghc.cabal.in')
| -rw-r--r-- | compiler/ghc.cabal.in | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/compiler/ghc.cabal.in b/compiler/ghc.cabal.in index 4ff65c4e61..3aff044b78 100644 --- a/compiler/ghc.cabal.in +++ b/compiler/ghc.cabal.in @@ -24,7 +24,7 @@ Category: Development Build-Type: Custom extra-source-files: - GHC/Builtin/primops.txt.pp + GHC/Builtin/primops.txt.pp GHC/Builtin/bytearray-ops.txt.pp Unique.h CodeGen.Platform.h @@ -707,6 +707,7 @@ Library GHC.Types.Unique.DSet GHC.Types.Unique.FM GHC.Types.Unique.Map + GHC.Types.Unique.MemoFun GHC.Types.Unique.SDFM GHC.Types.Unique.Set GHC.Types.Unique.Supply |