| Commit message (Collapse) | Author | Age | Files | Lines |
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This test triggers the bad code path identified by #20509 where an entry
into the EPS caused by importing Control.Applicative will retain a stale
HomePackageTable.
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previous attempts at fixing #11547 and #20455 were reverted because they
showed some quadratic behaviour, and the test case T15052 was added to
catch that.
I believe that similar quadratic behavor can be triggered with current
master, by using type definitions rather than value definitions, so this
adds a test case similar to T14052. I have hopes that my attempts at
fixing #11547 will lead to code that avoid the quadratic increase here.
Or not, we will see. In any case, having this in `master` and included
in future comparisons will be useful.
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This patch enables worker/wrapper for nested constructed products, as described
in `Note [Nested CPR]`. The machinery for expressing Nested CPR was already
there, since !5054. Worker/wrapper is equipped to exploit Nested CPR annotations
since !5338. CPR analysis already handles applications in batches since !5753.
This patch just needs to flip a few more switches:
1. In `cprTransformDataConWork`, we need to look at the field expressions
and their `CprType`s to see whether the evaluation of the expressions
terminates quickly (= is in HNF) or if they are put in strict fields.
If that is the case, then we retain their CPR info and may unbox nestedly
later on. More details in `Note [Nested CPR]`.
2. Enable nested `ConCPR` signatures in `GHC.Types.Cpr`.
3. In the `asConCpr` call in `GHC.Core.Opt.WorkWrap.Utils`, pass CPR info of
fields to the `Unbox`.
4. Instead of giving CPR signatures to DataCon workers and wrappers, we now have
`cprTransformDataConWork` for workers and treat wrappers by analysing their
unfolding. As a result, the code from GHC.Types.Id.Make went away completely.
5. I deactivated worker/wrappering for recursive DataCons and wrote a function
`isRecDataCon` to detect them. We really don't want to give `repeat` or
`replicate` the Nested CPR property.
See Note [CPR for recursive data structures] for which kind of recursive
DataCons we target.
6. Fix a couple of tests and their outputs.
I also documented that CPR can destroy sharing and lead to asymptotic increase
in allocations (which is tracked by #13331/#19326) in
`Note [CPR for data structures can destroy sharing]`.
Nofib results:
```
--------------------------------------------------------------------------------
Program Allocs Instrs
--------------------------------------------------------------------------------
ben-raytrace -3.1% -0.4%
binary-trees +0.8% -2.9%
digits-of-e2 +5.8% +1.2%
event +0.8% -2.1%
fannkuch-redux +0.0% -1.4%
fish 0.0% -1.5%
gamteb -1.4% -0.3%
mkhprog +1.4% +0.8%
multiplier +0.0% -1.9%
pic -0.6% -0.1%
reptile -20.9% -17.8%
wave4main +4.8% +0.4%
x2n1 -100.0% -7.6%
--------------------------------------------------------------------------------
Min -95.0% -17.8%
Max +5.8% +1.2%
Geometric Mean -2.9% -0.4%
```
The huge wins in x2n1 (loopy list) and reptile (see #19970) are due to
refraining from unboxing (:). Other benchmarks like digits-of-e2 or wave4main
regress because of that. Ultimately there are no great improvements due to
Nested CPR alone, but at least it's a win.
Binary sizes decrease by 0.6%.
There are a significant number of metric decreases. The most notable ones (>1%):
```
ManyAlternatives(normal) ghc/alloc 771656002.7 762187472.0 -1.2%
ManyConstructors(normal) ghc/alloc 4191073418.7 4114369216.0 -1.8%
MultiLayerModules(normal) ghc/alloc 3095678333.3 3128720704.0 +1.1%
PmSeriesG(normal) ghc/alloc 50096429.3 51495664.0 +2.8%
PmSeriesS(normal) ghc/alloc 63512989.3 64681600.0 +1.8%
PmSeriesV(normal) ghc/alloc 62575424.0 63767208.0 +1.9%
T10547(normal) ghc/alloc 29347469.3 29944240.0 +2.0%
T11303b(normal) ghc/alloc 46018752.0 47367576.0 +2.9%
T12150(optasm) ghc/alloc 81660890.7 82547696.0 +1.1%
T12234(optasm) ghc/alloc 59451253.3 60357952.0 +1.5%
T12545(normal) ghc/alloc 1705216250.7 1751278952.0 +2.7%
T12707(normal) ghc/alloc 981000472.0 968489800.0 -1.3% GOOD
T13056(optasm) ghc/alloc 389322664.0 372495160.0 -4.3% GOOD
T13253(normal) ghc/alloc 337174229.3 341954576.0 +1.4%
T13701(normal) ghc/alloc 2381455173.3 2439790328.0 +2.4% BAD
T14052(ghci) ghc/alloc 2162530642.7 2139108784.0 -1.1%
T14683(normal) ghc/alloc 3049744728.0 2977535064.0 -2.4% GOOD
T14697(normal) ghc/alloc 362980213.3 369304512.0 +1.7%
T15164(normal) ghc/alloc 1323102752.0 1307480600.0 -1.2%
T15304(normal) ghc/alloc 1304607429.3 1291024568.0 -1.0%
T16190(normal) ghc/alloc 281450410.7 284878048.0 +1.2%
T16577(normal) ghc/alloc 7984960789.3 7811668768.0 -2.2% GOOD
T17516(normal) ghc/alloc 1171051192.0 1153649664.0 -1.5%
T17836(normal) ghc/alloc 1115569746.7 1098197592.0 -1.6%
T17836b(normal) ghc/alloc 54322597.3 55518216.0 +2.2%
T17977(normal) ghc/alloc 47071754.7 48403408.0 +2.8%
T17977b(normal) ghc/alloc 42579133.3 43977392.0 +3.3%
T18923(normal) ghc/alloc 71764237.3 72566240.0 +1.1%
T1969(normal) ghc/alloc 784821002.7 773971776.0 -1.4% GOOD
T3294(normal) ghc/alloc 1634913973.3 1614323584.0 -1.3% GOOD
T4801(normal) ghc/alloc 295619648.0 292776440.0 -1.0%
T5321FD(normal) ghc/alloc 278827858.7 276067280.0 -1.0%
T5631(normal) ghc/alloc 586618202.7 577579960.0 -1.5%
T5642(normal) ghc/alloc 494923048.0 487927208.0 -1.4%
T5837(normal) ghc/alloc 37758061.3 39261608.0 +4.0%
T9020(optasm) ghc/alloc 257362077.3 254672416.0 -1.0%
T9198(normal) ghc/alloc 49313365.3 50603936.0 +2.6% BAD
T9233(normal) ghc/alloc 704944258.7 685692712.0 -2.7% GOOD
T9630(normal) ghc/alloc 1476621560.0 1455192784.0 -1.5%
T9675(optasm) ghc/alloc 443183173.3 433859696.0 -2.1% GOOD
T9872a(normal) ghc/alloc 1720926653.3 1693190072.0 -1.6% GOOD
T9872b(normal) ghc/alloc 2185618061.3 2162277568.0 -1.1% GOOD
T9872c(normal) ghc/alloc 1765842405.3 1733618088.0 -1.8% GOOD
TcPlugin_RewritePerf(normal) ghc/alloc 2388882730.7 2365504696.0 -1.0%
WWRec(normal) ghc/alloc 607073186.7 597512216.0 -1.6%
T9203(normal) run/alloc 107284064.0 102881832.0 -4.1%
haddock.Cabal(normal) run/alloc 24025329589.3 23768382560.0 -1.1%
haddock.base(normal) run/alloc 25660521653.3 25370321824.0 -1.1%
haddock.compiler(normal) run/alloc 74064171706.7 73358712280.0 -1.0%
```
The biggest exception to the rule is T13701 which seems to fluctuate as usual
(not unlike T12545). T14697 has a similar quality, being a generated
multi-module test. T5837 is small enough that it similarly doesn't measure
anything significant besides module loading overhead.
T13253 simply does one additional round of Simplification due to Nested CPR.
There are also some apparent regressions in T9198, T12234 and PmSeriesG that we
(@mpickering and I) were simply unable to reproduce locally. @mpickering tried
to run the CI script in a local Docker container and actually found that T9198
and PmSeriesG *improved*. In MRs that were rebased on top this one, like !4229,
I did not experience such increases. Let's not get hung up on these regression
tests, they were meant to test for asymptotic regressions.
The build-cabal test improves by 1.2% in -O0.
Metric Increase:
T10421
T12234
T12545
T13035
T13056
T13701
T14697
T18923
T5837
T9198
Metric Decrease:
ManyConstructors
T12545
T12707
T13056
T14683
T16577
T18223
T1969
T3294
T9203
T9233
T9675
T9872a
T9872b
T9872c
T9961
TcPlugin_RewritePerf
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While investigating #20106, I made a few refactorings to the pattern-match
checker that I don't want to lose. Here are the changes:
* Some key functions of the checker now have SCC annotations
* Better `-ddump-ec-trace` diagnostics for easier debugging. I added
'traceWhenFailPm' to see *why* a particular `MaybeT` computation fails and
made use of it in `instCon`.
I also increased the acceptance threshold of T11545, which seems to fail
randomly lately due to ghc/max flukes.
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This patch, provoked by regressions in the text package
(#19557), improves sharing of join points. This also fixes
the terrible behaviour in #20049.
See Note [Duplicating join points] in GHC.Core.Opt.Simplify.
* In the StrictArg case of mkDupableContWithDmds, don't
use Plan A for data constructors
* In postInlineUnconditionally, don't inline JoinIds
Avoids inlining join $j x = Just x
in case blah of
A -> $j x1
B -> $j x2
C -> $j x3
* In mkDupableStrictBind and mkDupableStrictAlt, create
join points (much) more often: exprIsTrivial rather than
exprIsDupable. This may be much, but we'll see.
Metric Decrease:
T12545
T13253-spj
T13719
T18140
T18282
T18304
T18698a
T18698b
Metric Increase:
T16577
T18923
T9961
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In a sequel of #19414, I wrote a script that measures min and max allocation
bounds of T12545 based on randomly modifying -dunique-increment. I got a spread
of as much as 4.8%. But instead of widening the acceptance window further (to
5%), I committed the script as part of this commit, so that false positive
increases can easily be diagnosed by comparing min and max bounds to HEAD.
Indeed, for !5814 we have seen T12545 go from -0.3% to 3.3% after a rebase.
I made sure that the min and max bounds actually stayed the same.
In the future, this kind of check can very easily be done in a matter of a
minute. Maybe we should increase the acceptance threshold if we need to check
often (leave a comment on #19414 if you had to check), but I've not been bitten
by it for half a year, which seems OK.
Metric Increase:
T12545
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This patch comprises of four different but closely related ideas. The
net result is fixing a large number of open issues with the driver
whilst making it simpler to understand.
1. Use the hash of the source file to determine whether the source file
has changed or not. This makes the recompilation checking more robust to
modern build systems which are liable to copy files around changing
their modification times.
2. Remove the concept of a "stable module", a stable module was one
where the object file was older than the source file, and all transitive
dependencies were also stable. Now we don't rely on the modification
time of the source file, the notion of stability is moot.
3. Fix TH/plugin recompilation after the removal of stable modules. The
TH recompilation check used to rely on stable modules. Now there is a
uniform and simple way, we directly track the linkables which were
loaded into the interpreter whilst compiling a module. This is an
over-approximation but more robust wrt package dependencies changing.
4. Fix recompilation checking for dynamic object files. Now we actually
check if the dynamic object file exists when compiling with -dynamic-too
Fixes #19774 #19771 #19758 #17434 #11556 #9121 #8211 #16495 #7277 #16093
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Fixes #19731
-------------------------
Metric Decrease:
T11545
Metric Increase:
T12545
T15304
-------------------------
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This makes it more robust to people running it with `quick` flavour and
so on.
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The test max memory usage improves dramatically with the fixes to
memory usage in demand analyser from #15455
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Fixes #11545
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In version 0.12.2.0 of vector when used with GHC-9.0 we
rebox values from storeable mutable vectors.
This should catch such a change in the future.
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- Remove GHC.OldList
- Remove Data.OldList
- compat-unqualified-imports is no-op
- update haddock submodule
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As #19293 realises, this one keeps on flip flopping by 2.5%
depending on how many modules there are within the GHC package.
We should revert this once we figured out how to fix what's going on.
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This test flip-flops by +-1% in arbitrary changes in CI.
While playing around with `-dunique-increment`, I could reproduce
variations of 3% in compiler allocations, so I set the acceptance window
accordingly.
Fixes #19414.
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This reverts commit 4a9d856d21c67b3328e26aa68a071ec9a824a7bb.
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In GHC.Core.SimpleOpt, I found that its inlining could duplicate
an arbitary redex inside a lambda! Consider (\xyz. x+y). The
occurrence-analysis treats the lamdda as a group, and says that
both x and y occur once, even though the occur under the lambda-z.
See Note [Occurrence analysis for lambda binders] in OccurAnal.
When the lambda is under-applied in a call, the Simplifier is
careful to zap the occ-info on x,y, because they appear under the \z.
(See the call to zapLamBndrs in simplExprF1.) But SimpleOpt
missed this test, resulting in #19347.
So this patch
* commons up the binder-zapping in GHC.Core.Utils.zapLamBndrs.
* Calls this new function from GHC.Core.Opt.Simplify
* Adds a call to zapLamBndrs to GHC.Core.SimpleOpt.simple_app
This change makes test T12990 regress somewhat, but it was always
very delicate, so I'm going to put up with that.
In this voyage I also discovered a small, rather unrelated infelicity
in the Simplifier:
* In GHC.Core.Opt.Simplify.simplNonRecX we should apply isStrictId
to the OutId not the InId. See Note [Dark corner with levity polymorphism]
It may never "bite", because SimpleOpt should have inlined all
the levity-polymorphic compulsory inlnings already, but somehow
it bit me at one point and it's generally a more solid thing
to do.
Fixing the main bug increases runtime allocation in test
perf/should_run/T12990, for (acceptable) reasons explained in a
comement on
Metric Increase:
T12990
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This commit also consolidates documentation in the user
manual around UndecidableSuperClasses, UndecidableInstances,
and FlexibleContexts.
Close #19186.
Close #19187.
Test case: typecheck/should_compile/T19186,
typecheck/should_fail/T19187{,a}
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Instead of producing auxiliary con2tag bindings we now rely on
dataToTag#, eliminating a fair bit of generated code.
Co-Authored-By: Ben Gamari <ben@well-typed.com>
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As outlined in #18903, interleaving usage and strictness demands not
only means a more compact demand representation, but also allows us to
express demands that we weren't easily able to express before.
Call demands are *relative* in the sense that a call demand `Cn(cd)`
on `g` says "`g` is called `n` times. *Whenever `g` is called*, the
result is used according to `cd`". Example from #18903:
```hs
h :: Int -> Int
h m =
let g :: Int -> (Int,Int)
g 1 = (m, 0)
g n = (2 * n, 2 `div` n)
{-# NOINLINE g #-}
in case m of
1 -> 0
2 -> snd (g m)
_ -> uncurry (+) (g m)
```
Without the interleaved representation, we would just get `L` for the
strictness demand on `g`. Now we are able to express that whenever
`g` is called, its second component is used strictly in denoting `g`
by `1C1(P(1P(U),SP(U)))`. This would allow Nested CPR to unbox the
division, for example.
Fixes #18903.
While fixing regressions, I also discovered and fixed #18957.
Metric Decrease:
T13253-spj
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These all have a maximum residency of over 2 GB.
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Progress towards #18842. As @sgraf812 points out, widening the window is
dangerous until the exponential described in #17658 is fixed. But this
test has caused enough misery and is low stakes enough that we and
@bgamari think it's worth it in this one case for the time being.
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Makes it possible for GHC to optimize away intermediate Generic representation
for more types.
Metric Increase:
T12227
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-------------------------
Metric Decrease:
T12425
Metric Increase:
T17516
-------------------------
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Replace options like collect_stats(['peak_megabytes_allocated'],4) with
collect_runtime_residency(4) and so forth. Reason being that the later
also supplies some default RTS arguments which make sure residency does
not fluctuate too much.
The new flags mean we get new (hopefully more accurate) baselines so
accept the stat changes.
-------------------------
Metric Decrease:
T4029
T4334
T7850
Metric Increase:
T13218
T7436
-------------------------
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This patch fixes #18223, which made GHC generate an exponential
amount of code. There are three quite separate changes in here
1. Re-engineer eta-expansion (again). The eta-expander was
generating lots of intermediate stuff, which could be optimised
away, but which choked the simplifier meanwhile. Relatively
easy to kill it off at source.
See Note [The EtaInfo mechanism] in GHC.Core.Opt.Arity.
The main new thing is the use of pushCoArg in getArg_maybe.
2. Stop Specialise specalising DFuns. This is the cause of a huge
(and utterly unnecessary) blowup in program size in #18223.
See Note [Do not specialise DFuns] in GHC.Core.Opt.Specialise.
I also refactored the Specialise monad a bit... it was silly,
because it passed on unchanging values as if they were mutable
state.
3. Do an extra Simplifer run, after SpecConstra and before
late-Specialise. I found (investigating perf/compiler/T16473)
that failing to do this was crippling *both* SpecConstr *and*
Specialise. See Note [Simplify after SpecConstr] in
GHC.Core.Opt.Pipeline.
This change does mean an extra run of the Simplifier, but only
with -O2, and I think that's acceptable.
T16473 allocates *three* times less with this change. (I changed
it to check runtime rather than compile time.)
Some smaller consequences
* I moved pushCoercion, pushCoArg and friends from SimpleOpt
to Arity, because it was needed by the new etaInfoApp.
And pushCoValArg now returns a MCoercion rather than Coercion for
the argument Coercion.
* A minor, incidental improvement to Core pretty-printing
This does fix #18223, (which was otherwise uncompilable. Hooray. But
there is still a big intermediate because there are some very deeply
nested types in that program.
Modest reductions in compile-time allocation on a couple of benchmarks
T12425 -2.0%
T13253 -10.3%
Metric increase with -O2, due to extra simplifier run
T9233 +5.8%
T12227 +1.8%
T15630 +5.0%
There is a spurious apparent increase on heap residency on T9630,
on some architectures at least. I tried it with -G1 and the residency
is essentially unchanged.
Metric Increase
T9233
T12227
T9630
Metric Decrease
T12425
T13253
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Previously it collected everything, including "max bytes used". This is
problematic since the test makes no attempt to control for deviations in
GC timing, resulting in high variability. Fix this by only collecting
"bytes allocated".
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Specifically:
#13253 exponential inlining
#10421 ditto
#18140 strict constructors
#18282 another nested-function call case
This patch makes one really significant changes: change the way that
mkDupableCont handles StrictArg. The details are explained in
GHC.Core.Opt.Simplify Note [Duplicating StrictArg].
Specific changes
* In mkDupableCont, when making auxiliary bindings for the other arguments
of a call, add extra plumbing so that we don't forget the demand on them.
Otherwise we haev to wait for another round of strictness analysis. But
actually all the info is to hand. This change affects:
- Make the strictness list in ArgInfo be [Demand] instead of [Bool],
and rename it to ai_dmds.
- Add as_dmd to ValArg
- Simplify.makeTrivial takes a Demand
- mkDupableContWithDmds takes a [Demand]
There are a number of other small changes
1. For Ids that are used at most once in each branch of a case, make
the occurrence analyser record the total number of syntactic
occurrences. Previously we recorded just OneBranch or
MultipleBranches.
I thought this was going to be useful, but I ended up barely
using it; see Note [Note [Suppress exponential blowup] in
GHC.Core.Opt.Simplify.Utils
Actual changes:
* See the occ_n_br field of OneOcc.
* postInlineUnconditionally
2. I found a small perf buglet in SetLevels; see the new
function GHC.Core.Opt.SetLevels.hasFreeJoin
3. Remove the sc_cci field of StrictArg. I found I could get
its information from the sc_fun field instead. Less to get
wrong!
4. In ArgInfo, arrange that ai_dmds and ai_discs have a simpler
invariant: they line up with the value arguments beyond ai_args
This allowed a bit of nice refactoring; see isStrictArgInfo,
lazyArgcontext, strictArgContext
There is virtually no difference in nofib. (The runtime numbers
are bogus -- I tried a few manually.)
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
fft +0.0% -2.0% -48.3% -49.4% 0.0%
multiplier +0.0% -2.2% -50.3% -50.9% 0.0%
--------------------------------------------------------------------------------
Min -0.4% -2.2% -59.2% -60.4% 0.0%
Max +0.0% +0.1% +3.3% +4.9% 0.0%
Geometric Mean +0.0% -0.0% -33.2% -34.3% -0.0%
Test T18282 is an existing example of these deeply-nested strict calls.
We get a big decrease in compile time (-85%) because so much less
inlining takes place.
Metric Decrease:
T18282
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This test is positively tiny and consequently the bytes allocated
measurement will be relatively noisy. Consequently I have seen this
fail spuriously quite often.
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Ticket #18282 showed that the result discount given by conSize
was massively too large. This patch reduces that discount to
a constant 10, which just balances the cost of the constructor
application itself.
Note [Constructor size and result discount] elaborates, as
does the ticket #18282.
Reducing result discount reduces inlining, which affects perf. I
found that I could increase the unfoldingUseThrehold from 80 to 90 in
compensation; in combination with the result discount change I get
these overall nofib numbers:
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
boyer -0.2% +5.4% -3.2% -3.4% 0.0%
cichelli -0.1% +5.9% -11.2% -11.7% 0.0%
compress2 -0.2% +9.6% -6.0% -6.8% 0.0%
cryptarithm2 -0.1% -3.9% -6.0% -5.7% 0.0%
gamteb -0.2% +2.6% -13.8% -14.4% 0.0%
genfft -0.1% -1.6% -29.5% -29.9% 0.0%
gg -0.0% -2.2% -17.2% -17.8% -20.0%
life -0.1% -2.2% -62.3% -63.4% 0.0%
mate +0.0% +1.4% -5.1% -5.1% -14.3%
parser -0.2% -2.1% +7.4% +6.7% 0.0%
primetest -0.2% -12.8% -14.3% -14.2% 0.0%
puzzle -0.2% +2.1% -10.0% -10.4% 0.0%
rsa -0.2% -11.7% -3.7% -3.8% 0.0%
simple -0.2% +2.8% -36.7% -38.3% -2.2%
wheel-sieve2 -0.1% -19.2% -48.8% -49.2% -42.9%
--------------------------------------------------------------------------------
Min -0.4% -19.2% -62.3% -63.4% -42.9%
Max +0.3% +9.6% +7.4% +11.0% +16.7%
Geometric Mean -0.1% -0.3% -17.6% -18.0% -0.7%
I'm ok with these numbers, remembering that this change removes
an *exponential* increase in code size in some in-the-wild cases.
I investigated compress2. The difference is entirely caused by this
function no longer inlining
WriteRoutines.$woutputCodes
= \ (w :: [CodeEvent]) ->
let result_s1Sr
= case WriteRoutines.outputCodes_$s$woutput w 0# 0# 8# 9# of
(# ww1, ww2 #) -> (ww1, ww2)
in (# case result_s1Sr of (x, _) ->
map @Int @Char WriteRoutines.outputCodes1 x
, case result_s1Sr of { (_, y) -> y } #)
It was right on the cusp before, driven by the excessive result
discount. Too bad!
Happily, the compiler/perf tests show a number of improvements:
T12227 compiler bytes-alloc -6.6%
T12545 compiler bytes-alloc -4.7%
T13056 compiler bytes-alloc -3.3%
T15263 runtime bytes-alloc -13.1%
T17499 runtime bytes-alloc -14.3%
T3294 compiler bytes-alloc -1.1%
T5030 compiler bytes-alloc -11.7%
T9872a compiler bytes-alloc -2.0%
T9872b compiler bytes-alloc -1.2%
T9872c compiler bytes-alloc -1.5%
Metric Decrease:
T12227
T12545
T13056
T15263
T17499
T3294
T5030
T9872a
T9872b
T9872c
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Previously it wasn't uncommon to see +/-1% fluctuations in compiler
allocations on this test.
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This test performs little work, so the most minor allocation
changes often cause the test to fail.
Increasing the threshold to 2% should help with this.
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* support detection of slow ghc-bignum backend (to replace the detection
of integer-simple use). There are still some test cases that the
native backend doesn't handle efficiently enough.
* remove tests for GMP only functions that have been removed from
ghc-bignum
* fix test results showing dependent packages (e.g. integer-gmp) or
showing suggested instances
* fix test using Integer/Natural API or showing internal names
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Just adding `{-# LANGUAGE BangPatterns #-}` makes the two other metrics
fluctuate by 13%.
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