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Only @inline should inline & constant fold
#34
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Expected issues: annotation arguments. |
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👍 |
puffnfresh
pushed a commit
to puffnfresh/scala
that referenced
this issue
Jul 30, 2015
In Scala 2.8.2, an optimization was added to create a static
cache for Symbol literals (ie, the results of `Symbol.apply("foo"))`.
This saves the map lookup on the second pass through code.
This actually was broken somewhere during the Scala 2.10 series,
after the addition of an overloaded `apply` method to `Symbol`.
The cache synthesis code was made aware of the overload and brought
back to working condition recently, in scala#3149.
However, this has uncovered a latent bug when the Symbol literals are
defined with traits.
One of the enclosed tests failed with:
jvm > t8933b-run.log
java.lang.IllegalAccessError: tried to access field MotherClass.symbol$1 from class MixinWithSymbol$class
at MixinWithSymbol$class.symbolFromTrait(A.scala:3)
at MotherClass.symbolFromTrait(Test.scala:1)
This commit simply disables the optimization if we are in a trait.
Alternative fixes might be: a) make the static Symbol cache field
public / b) "mixin" the static symbol cache. Neither of these
seem worth the effort and risk for an already fairly situational
optimization.
Here's how the optimization looks in a class:
% cat sandbox/test.scala; qscalac sandbox/test.scala && echo ":javap C" | qscala;
class C {
'a; 'b
}
Welcome to Scala version 2.11.5-20141106-145558-aa558dce6d (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_20).
Type in expressions to have them evaluated.
Type :help for more information.
scala> :javap C
Size 722 bytes
MD5 checksum 6bb00189166917254e8d40499ee7c887
Compiled from "test.scala"
public class C
{
public static {};
descriptor: ()V
flags: ACC_PUBLIC, ACC_STATIC
Code:
stack=2, locals=0, args_size=0
0: getstatic typelevel#16 // Field scala/Symbol$.MODULE$:Lscala/Symbol$;
3: ldc typelevel#18 // String a
5: invokevirtual typelevel#22 // Method scala/Symbol$.apply:(Ljava/lang/String;)Lscala/Symbol;
8: putstatic typelevel#26 // Field symbol$1:Lscala/Symbol;
11: getstatic typelevel#16 // Field scala/Symbol$.MODULE$:Lscala/Symbol$;
14: ldc typelevel#28 // String b
16: invokevirtual typelevel#22 // Method scala/Symbol$.apply:(Ljava/lang/String;)Lscala/Symbol;
19: putstatic typelevel#31 // Field symbol$2:Lscala/Symbol;
22: return
public C();
descriptor: ()V
flags: ACC_PUBLIC
Code:
stack=1, locals=1, args_size=1
0: aload_0
1: invokespecial typelevel#34 // Method java/lang/Object."<init>":()V
4: getstatic typelevel#26 // Field symbol$1:Lscala/Symbol;
7: pop
8: getstatic typelevel#31 // Field symbol$2:Lscala/Symbol;
11: pop
12: return
}
fixup
milessabin
referenced
this issue
in milessabin/scala
Apr 15, 2016
Rather than in implementation of the abstract method in the
expanded anonymous class.
This leads to more more efficient use of the constant pool,
code shapes more amenable to SAM inlining, and is compatible
with the old behaviour of `-Xexperimental` in Scala 2.11,
which ScalaJS now relies upon.
Manual test:
```
scala> :paste -raw
// Entering paste mode (ctrl-D to finish)
package p1; trait T { val x = 0; def apply(): Any }; class DelambdafyInline { def t: T = (() => "") }
// Exiting paste mode, now interpreting.
scala> :javap -c p1.DelambdafyInline
Compiled from "<pastie>"
public class p1.DelambdafyInline {
public p1.T t();
Code:
0: new scala#10 // class p1/DelambdafyInline$$anonfun$t$1
3: dup
4: aload_0
5: invokespecial scala#16 // Method p1/DelambdafyInline$$anonfun$t$1."<init>":(Lp1/DelambdafyInline;)V
8: areturn
public final java.lang.Object p1$DelambdafyInline$$$anonfun$1();
Code:
0: ldc scala#22 // String
2: areturn
public p1.DelambdafyInline();
Code:
0: aload_0
1: invokespecial scala#25 // Method java/lang/Object."<init>":()V
4: return
}
scala> :javap -c p1.DelambdafyInline$$anonfun$t$1
Compiled from "<pastie>"
public final class p1.DelambdafyInline$$anonfun$t$1 implements p1.T,scala.Serializable {
public static final long serialVersionUID;
public int x();
Code:
0: aload_0
1: getfield scala#25 // Field x:I
4: ireturn
public void p1$T$_setter_$x_$eq(int);
Code:
0: aload_0
1: iload_1
2: putfield scala#25 // Field x:I
5: return
public final java.lang.Object apply();
Code:
0: aload_0
1: getfield scala#34 // Field $outer:Lp1/DelambdafyInline;
4: invokevirtual scala#37 // Method p1/DelambdafyInline.p1$DelambdafyInline$$$anonfun$1:()Ljava/lang/Object;
7: areturn
public p1.DelambdafyInline$$anonfun$t$1(p1.DelambdafyInline);
Code:
0: aload_1
1: ifnonnull 6
4: aconst_null
5: athrow
6: aload_0
7: aload_1
8: putfield scala#34 // Field $outer:Lp1/DelambdafyInline;
11: aload_0
12: invokespecial scala#42 // Method java/lang/Object."<init>":()V
15: aload_0
16: invokespecial scala#45 // Method p1/T.$init$:()V
19: return
}
scala> :quit
```
Adriaan is to `git blame` for `reflection-mem-typecheck.scala`.
|
To resurrect this issue, please rework it as an issue/PR against Lightbend Scala (ie. scala/scala). |
milessabin
pushed a commit
that referenced
this issue
Jul 31, 2017
Non local returns aren't eliminated after inlined in 2.11 or 2.12
```
⚡ scala
Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_112).
Type in expressions for evaluation. Or try :help.
scala> @inlune def foo(a: => Any) = if ("".isEmpty) a else ""
<console>:11: error: not found: type inlune
@inlune def foo(a: => Any) = if ("".isEmpty) a else ""
^
scala> @inline def foo(a: => Any) = if ("".isEmpty) a else ""
foo: (a: => Any)Any
scala> class InlineReturn { def test: Any = foo(return "") }
defined class InlineReturn
scala> :javap -c InlineReturn#test
public java.lang.Object test();
Code:
0: new #4 // class java/lang/Object
3: dup
4: invokespecial #32 // Method java/lang/Object."<init>":()V
7: astore_1
8: getstatic #36 // Field $line4/$read$$iw$$iw$.MODULE$:L$line4/$read$$iw$$iw$;
11: aload_1
12: invokedynamic #59, 0 // InvokeDynamic #0:apply:(Ljava/lang/Object;)Lscala/Function0;
17: invokevirtual #63 // Method $line4/$read$$iw$$iw$.foo:(Lscala/Function0;)Ljava/lang/Object;
20: goto 44
23: astore_2
24: aload_2
25: invokevirtual #66 // Method scala/runtime/NonLocalReturnControl.key:()Ljava/lang/Object;
28: aload_1
29: if_acmpne 39
32: aload_2
33: invokevirtual #69 // Method scala/runtime/NonLocalReturnControl.value:()Ljava/lang/Object;
36: goto 41
39: aload_2
40: athrow
41: goto 44
44: areturn
Exception table:
from to target type
8 20 23 Class scala/runtime/NonLocalReturnControl
```
```
⚡ ~/scala/2.11.8/bin/scala
Welcome to Scala 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_112).
Type in expressions for evaluation. Or try :help.
scala> @inline def foo(a: => Any) = if ("".isEmpty) a else ""
foo: (a: => Any)Any
scala> class InlineReturn { def test: Any = foo(return "") }
defined class InlineReturn
scala> :javap -c InlineReturn#test
public java.lang.Object test();
Code:
0: new #4 // class java/lang/Object
3: dup
4: invokespecial #13 // Method java/lang/Object."<init>":()V
7: astore_1
8: getstatic #19 // Field .MODULE$:L;
11: new #21 // class InlineReturn$$anonfun$test$1
14: dup
15: aload_0
16: aload_1
17: invokespecial #24 // Method InlineReturn$$anonfun$test$1."<init>":(LInlineReturn;Ljava/lang/Object;)V
20: invokevirtual #28 // Method .foo:(Lscala/Function0;)Ljava/lang/Object;
23: goto 39
26: astore_2
27: aload_2
28: invokevirtual #31 // Method scala/runtime/NonLocalReturnControl.key:()Ljava/lang/Object;
31: aload_1
32: if_acmpne 40
35: aload_2
36: invokevirtual #34 // Method scala/runtime/NonLocalReturnControl.value:()Ljava/lang/Object;
39: areturn
40: aload_2
41: athrow
Exception table:
from to target type
8 26 26 Class scala/runtime/NonLocalReturnControl
scala> :quit
```
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See https://issues.scala-lang.org/browse/SI-7542.
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