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author | Jason Zaugg <jzaugg@gmail.com> | 2014-04-24 10:53:20 +0200 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2014-05-08 10:33:45 +0200 |
commit | b154269b0e7447cfbf7fdb73c8c4efcdca545b11 (patch) | |
tree | 662076793ed1333d8d0393efac365f9fe3cd80b9 /src | |
parent | aa3a3dd6a420f57b0fe815bfcb2b23fbb4284468 (diff) | |
download | scala-b154269b0e7447cfbf7fdb73c8c4efcdca545b11.tar.gz scala-b154269b0e7447cfbf7fdb73c8c4efcdca545b11.tar.bz2 scala-b154269b0e7447cfbf7fdb73c8c4efcdca545b11.zip |
SI-8531 Better space efficiency for patmat analysis
By adding logging to `clause`, I found that the majority of
calls provide 0 or 1 elements. In SI-7020 / 69557da55, we changed this
method to use a `LinkedHashSet` to have deterministic results
for clauses with more elements. But I suspect that this
contributes to higher memory usage from the pattern matcher.
The enclosed test case, carefully whittled down by @oxbowlakes,
used to consume an inordinate amount of memory and time.
After this patch, it is back to 2.10.4 performance.
I have run `neg/t7020.scala` in a loop and it still is deterministic.
Diffstat (limited to 'src')
-rw-r--r-- | src/compiler/scala/tools/nsc/transform/patmat/Solving.scala | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/patmat/Solving.scala b/src/compiler/scala/tools/nsc/transform/patmat/Solving.scala index 1902606d86..31b1ffa912 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/Solving.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/Solving.scala @@ -29,8 +29,12 @@ trait Solving extends Logic { type Clause = collection.Set[Lit] // a clause is a disjunction of distinct literals def clause(l: Lit*): Clause = ( - // neg/t7020.scala changes output 1% of the time, the non-determinism is quelled with this linked set - mutable.LinkedHashSet(l: _*) + if (l.lengthCompare(1) <= 0) { + l.toSet // SI-8531 Avoid LinkedHashSet's bulk for 0 and 1 element clauses + } else { + // neg/t7020.scala changes output 1% of the time, the non-determinism is quelled with this linked set + mutable.LinkedHashSet(l: _*) + } ) type Lit |