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Optimizing performance of LazyVals
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11 files changed

+225
-24
lines changed

11 files changed

+225
-24
lines changed

‎bench-micro/results_isStable.json

Whitespace-only changes.

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/InitializedAccess.scala

Lines changed: 11 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -14,16 +14,17 @@ import java.util.concurrent.TimeUnit
1414
@State(Scope.Benchmark)
1515
class InitializedAccess {
1616

17-
var holder: LazyHolder = _
17+
var holder: LazyHolder = _
1818

19-
@Setup
20-
def prepare: Unit = {
21-
holder = new LazyHolder
22-
holder.value
23-
}
19+
@Setup
20+
def prepare: Unit = {
21+
holder = new LazyHolder
22+
holder.value
23+
}
2424

25-
@Benchmark
26-
def measureInitialized(bh: Blackhole) = {
27-
bh.consume(holder.value)
28-
}
25+
@Benchmark
26+
def measureInitialized(bh: Blackhole) = {
27+
bh.consume(holder)
28+
bh.consume(holder.value)
29+
}
2930
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/InitializedAccessAny.scala

Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,30 @@
1+
package dotty.tools.benchmarks.lazyvals
2+
3+
import org.openjdk.jmh.annotations._
4+
import LazyVals.LazyAnyHolder
5+
import org.openjdk.jmh.infra.Blackhole
6+
import java.util.concurrent.TimeUnit
7+
8+
@BenchmarkMode(Array(Mode.AverageTime))
9+
@Fork(2)
10+
@Threads(1)
11+
@Warmup(iterations = 5)
12+
@Measurement(iterations = 5)
13+
@OutputTimeUnit(TimeUnit.NANOSECONDS)
14+
@State(Scope.Benchmark)
15+
class InitializedAccessAny {
16+
17+
var holder: LazyAnyHolder = _
18+
19+
@Setup
20+
def prepare: Unit = {
21+
holder = new LazyAnyHolder
22+
holder.value
23+
}
24+
25+
@Benchmark
26+
def measureInitialized(bh: Blackhole) = {
27+
bh.consume(holder)
28+
bh.consume(holder.value)
29+
}
30+
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/InitializedAccessGeneric.scala

Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,30 @@
1+
package dotty.tools.benchmarks.lazyvals
2+
3+
import org.openjdk.jmh.annotations._
4+
import LazyVals.LazyGenericHolder
5+
import org.openjdk.jmh.infra.Blackhole
6+
import java.util.concurrent.TimeUnit
7+
8+
@BenchmarkMode(Array(Mode.AverageTime))
9+
@Fork(2)
10+
@Threads(1)
11+
@Warmup(iterations = 5)
12+
@Measurement(iterations = 5)
13+
@OutputTimeUnit(TimeUnit.NANOSECONDS)
14+
@State(Scope.Benchmark)
15+
class InitializedAccessGeneric {
16+
17+
var holder: LazyGenericHolder[String] = _
18+
19+
@Setup
20+
def prepare: Unit = {
21+
holder = new LazyGenericHolder[String]("foo")
22+
holder.value
23+
}
24+
25+
@Benchmark
26+
def measureInitialized(bh: Blackhole) = {
27+
bh.consume(holder)
28+
bh.consume(holder.value)
29+
}
30+
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/InitializedAccessMultiple.scala

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
package dotty.tools.benchmarks.lazyvals
2+
3+
import org.openjdk.jmh.annotations._
4+
import LazyVals.LazyHolder
5+
import org.openjdk.jmh.infra.Blackhole
6+
import java.util.concurrent.TimeUnit
7+
8+
@BenchmarkMode(Array(Mode.AverageTime))
9+
@Fork(2)
10+
@Threads(1)
11+
@Warmup(iterations = 5)
12+
@Measurement(iterations = 5)
13+
@OutputTimeUnit(TimeUnit.NANOSECONDS)
14+
@State(Scope.Benchmark)
15+
class InitializedAccessMultiple {
16+
17+
var holders: Array[LazyHolder] = _
18+
19+
@Setup
20+
def prepare: Unit = {
21+
holders = Array.fill(100){ new LazyHolder }
22+
}
23+
24+
@Benchmark
25+
def measureInitialized(bh: Blackhole) = {
26+
var i = 0
27+
while(i < 100) {
28+
val currentHolder = holders(i)
29+
bh.consume(currentHolder)
30+
bh.consume(currentHolder.value)
31+
i = i + 1
32+
}
33+
}
34+
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/InitializedAccessString.scala

Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,30 @@
1+
package dotty.tools.benchmarks.lazyvals
2+
3+
import org.openjdk.jmh.annotations._
4+
import LazyVals.LazyStringHolder
5+
import org.openjdk.jmh.infra.Blackhole
6+
import java.util.concurrent.TimeUnit
7+
8+
@BenchmarkMode(Array(Mode.AverageTime))
9+
@Fork(2)
10+
@Threads(1)
11+
@Warmup(iterations = 5)
12+
@Measurement(iterations = 5)
13+
@OutputTimeUnit(TimeUnit.NANOSECONDS)
14+
@State(Scope.Benchmark)
15+
class InitializedAccessString {
16+
17+
var holder: LazyStringHolder = _
18+
19+
@Setup
20+
def prepare: Unit = {
21+
holder = new LazyStringHolder
22+
holder.value
23+
}
24+
25+
@Benchmark
26+
def measureInitialized(bh: Blackhole) = {
27+
bh.consume(holder)
28+
bh.consume(holder.value)
29+
}
30+
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/LazyVals.scala

Lines changed: 48 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,53 @@
11
package dotty.tools.benchmarks.lazyvals
2-
2+
import java.util.concurrent.CountDownLatch
33
object LazyVals {
4+
5+
trait Foo
6+
class Bar1 extends Foo
7+
class Bar2 extends Foo
8+
class Bar3 extends Foo
9+
class Bar4 extends Foo
10+
class Bar5 extends Bar4
11+
12+
class LazyStringHolder {
13+
14+
lazy val value: String = {
15+
System.nanoTime() % 5 match {
16+
case 0 => "abc"
17+
case 1 => "def"
18+
case 2 => "ghi"
19+
case 3 => "jkl"
20+
case 4 => "mno"
21+
}
22+
}
23+
}
24+
425
class LazyHolder {
5-
lazy val value = 1
26+
27+
lazy val value: List[Int] = {
28+
System.nanoTime() % 5 match {
29+
case 0 => 1 :: 2 :: Nil
30+
case 1 => Nil
31+
case 2 => 1 :: Nil
32+
case 3 => Nil
33+
case 4 => 1 :: 2 :: 3 :: Nil
34+
}
35+
}
36+
}
37+
38+
class LazyGenericHolder[A](v: => A) {
39+
lazy val value: A = v
40+
}
41+
42+
class LazyAnyHolder {
43+
lazy val value: Any = {
44+
System.nanoTime() % 5 match {
45+
case 0 => new Bar1
46+
case 1 => new Bar2
47+
case 2 => new Bar3
48+
case 3 => new Bar4
49+
case 4 => new Bar4
50+
}
51+
}
652
}
753
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/UninitializedAccess copy.scala renamed to ‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/UninitializedAccess.scala

Lines changed: 3 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -14,16 +14,12 @@ import java.util.concurrent.TimeUnit
1414
@State(Scope.Benchmark)
1515
class UninitializedAccess {
1616

17-
var holder: LazyHolder = _
18-
19-
@Setup
20-
def prepare: Unit = {
21-
holder = new LazyHolder
22-
}
23-
2417
@Benchmark
2518
def measureInitialized(bh: Blackhole) = {
19+
var i = 0
20+
val holder = new LazyHolder
2621
bh.consume(holder)
2722
bh.consume(holder.value)
23+
i = i + 1
2824
}
2925
}

‎bench-micro/src/main/scala/dotty/tools/benchmarks/lazyvals/UninitializedAccessMultiple.scala

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,27 @@
1+
package dotty.tools.benchmarks.lazyvals
2+
3+
import org.openjdk.jmh.annotations._
4+
import LazyVals.LazyHolder
5+
import org.openjdk.jmh.infra.Blackhole
6+
import java.util.concurrent.TimeUnit
7+
8+
@BenchmarkMode(Array(Mode.AverageTime))
9+
@Fork(2)
10+
@Threads(1)
11+
@Warmup(iterations = 5)
12+
@Measurement(iterations = 5)
13+
@OutputTimeUnit(TimeUnit.NANOSECONDS)
14+
@State(Scope.Benchmark)
15+
class UninitializedAccessMultiple {
16+
17+
@Benchmark
18+
def measureInitialized(bh: Blackhole) = {
19+
var i = 0
20+
while(i < 100) {
21+
val holder = new LazyHolder
22+
bh.consume(holder)
23+
bh.consume(holder.value)
24+
i = i + 1
25+
}
26+
}
27+
}

‎compiler/src/dotty/tools/dotc/transform/LazyVals.scala

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -390,12 +390,19 @@ class LazyVals extends MiniPhase with IdentityDenotTransformer {
390390
val rhs = memberDef.rhs
391391
val rhsMappedOwner = rhs.changeOwnerAfter(memberDef.symbol, lazyInitMethodSymbol, this)
392392
val valueSymbol = newSymbol(accessorMethodSymbol, lazyNme.result, Synthetic | Mutable, defn.ObjectType)
393+
394+
val immediateValueCondition =
395+
if (controlState.tpe <:< tp) then
396+
ref(valueSymbol).select(defn.Any_!=).appliedTo(nullLiteral).select(nme.And).appliedTo(ref(valueSymbol).select(defn.Any_isInstanceOf).appliedToTypeTree(controlState)
397+
.select(nme.UNARY_!).appliedToNone)
398+
else
399+
ref(valueSymbol).select(defn.Any_isInstanceOf).appliedToTypeTree(TypeTree(tp))
400+
393401
val accessorBody =
394402
Block(
395403
ValDef(valueSymbol, ref(target)) :: Nil,
396404
If( // if _x != null && !_x.isInstanceOf[LazyValControlState] then
397-
ref(valueSymbol).select(defn.Any_!=).appliedTo(nullLiteral).select(nme.And).appliedTo(ref(valueSymbol).select(defn.Any_isInstanceOf).appliedToTypeTree(controlState)
398-
.select(nme.UNARY_!).appliedToNone),
405+
immediateValueCondition,
399406
Return(ref(valueSymbol).ensureConforms(tp), accessorMethodSymbol), // then return _x.asInstanceOf[A]
400407
If(
401408
ref(valueSymbol).select(defn.Any_==).appliedTo(nullValue),
@@ -419,11 +426,11 @@ class LazyVals extends MiniPhase with IdentityDenotTransformer {
419426
ref(lockSymb).select(lazyNme.RLazyVals.waitingRelease).ensureApplied)
420427
}
421428
// finally block
422-
val fin = If(
429+
val fin = Block(If(
423430
objCasFlag.appliedTo(thiz, offset, evaluating, ref(resSymb)).select(nme.UNARY_!).appliedToNone,
424431
lockRel,
425432
unitLiteral
426-
).withType(defn.UnitType)
433+
) :: Nil, Return(ref(resSymb), lazyInitMethodSymbol)).withType(defn.UnitType)
427434
// entire try block
428435
val evaluate = Try(
429436

‎library/src/scala/runtime/LazyVals.scala

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -43,7 +43,7 @@ object LazyVals {
4343

4444
/* ------------- Start of public API ------------- */
4545

46-
trait LazyValControlState
46+
sealed trait LazyValControlState
4747

4848
/**
4949
* Used to indicate the state of a lazy val that is being

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