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authorSebastian Graf <sebastian.graf@kit.edu>2022-03-12 15:22:13 +0100
committerMarge Bot <ben+marge-bot@smart-cactus.org>2022-03-14 15:09:01 -0400
commit8ff32124c8cd37050f3dc7cbb32b8d41711ebcaf (patch)
tree1f6649ef979b6024c2bf45cd5849ed6c942e1d8f /compiler/ghc.cabal.in
parent8eadea670adb5de49ddba7e23d04ec8242ba76a3 (diff)
downloadhaskell-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.in3
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