Review/fields lazies #25
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- Avoid boxing the {Object, Int, ...}Ref itself by storing it in
a val, not a var
- Avoid box/unbox of primitive lazy expressions due which are added
to "adapt" it to the erased type of the fictional syncronized
method, by using a `return`. We have to add a dummy throw after
the synchronized block, but this is elimnated by the always-on
DCE in the code generator.
```
⚡ qscalac -Xprint:mixin $(f "class C { def foo = { lazy val x = 42; x }}"); javap -private -c -cp . C
[[syntax trees at end of mixin]] // a.scala
package <empty> {
class C extends Object {
def foo(): Int = {
lazy <artifact> val x$lzy: scala.runtime.LazyInt = new scala.runtime.LazyInt();
C.this.x$1(x$lzy)
};
final private[this] def x$1(x$lzy$1: scala.runtime.LazyInt): Int = {
x$lzy$1.synchronized({
if (x$lzy$1.initialized().unary_!())
{
x$lzy$1.initialized_=(true);
x$lzy$1.value_=(42)
};
return x$lzy$1.value()
});
throw null
};
def <init>(): C = {
C.super.<init>();
()
}
}
}
Compiled from "a.scala"
public class C {
public int foo();
Code:
0: new #12 // class scala/runtime/LazyInt
3: dup
4: invokespecial #16 // Method scala/runtime/LazyInt."<init>":()V
7: astore_1
8: aload_1
9: invokestatic #20 // Method x$1:(Lscala/runtime/LazyInt;)I
12: ireturn
private static final int x$1(scala.runtime.LazyInt);
Code:
0: aload_0
1: dup
2: astore_1
3: monitorenter
4: aload_0
5: invokevirtual #31 // Method scala/runtime/LazyInt.initialized:()Z
8: ifne 22
11: aload_0
12: iconst_1
13: invokevirtual #35 // Method scala/runtime/LazyInt.initialized_$eq:(Z)V
16: aload_0
17: bipush 42
19: invokevirtual #39 // Method scala/runtime/LazyInt.value_$eq:(I)V
22: aload_0
23: invokevirtual #42 // Method scala/runtime/LazyInt.value:()I
26: istore_2
27: goto 33
30: aload_1
31: monitorexit
32: athrow
33: aload_1
34: monitorexit
35: iload_2
36: ireturn
Exception table:
from to target type
4 30 30 Class java/lang/Throwable
public C();
Code:
0: aload_0
1: invokespecial #43 // Method java/lang/Object."<init>":()V
4: return
}
```
25 tasks
|
are we still early enough in the pipeline that we can rely on non-local returns being rewritten? I tried the community build on this and it failed, but I didn't look into why yet https://scala-ci.typesafe.com/view/scala-2.12.x/job/scala-2.12.x-integrate-community-build/490/console |
|
It isn't actually a non-local return. But I like your suggestion to use a |
retronym
pushed a commit
that referenced
this pull request
May 15, 2018
Unlike normal diff, the git diff feature wasn't using the filtered
check file under `--show-diff`.
Now the sample displays just the bad line.
```
!! 1 - neg/t7494-no-options [output differs]
% diff /home/apm/projects/snytt/test/files/neg/t7494-no-options-neg.log /home/apm/projects/snytt/test/files/neg/t7494-no-options.check
@@ -1,7 +1,7 @@
error: Error: ploogin takes no options
phase name id description
---------- -- -----------
- parser 1 parse source into ASTs, perform simple desugaring
+ parser 0 parse source into ASTs, perform simple desugaring
namer 2 resolve names, attach symbols to named trees
packageobjects 3 load package objects
typer 4 the meat and potatoes: type the trees
```
retronym
added a commit
that referenced
this pull request
Jun 24, 2019
And use this as the target of the default methods or
statically resolved super or $init calls.
The call-site change is predicated on `-Yuse-trait-statics`
as a stepping stone for experimentation / bootstrapping.
I have performed this transformation in the backend,
rather than trying to reflect this in the view from
Scala symbols + ASTs.
Once we commit to this change, we can remove the
`lateInterfaces` bookkeeping from the backend, as we no
long will need to add ancestor interfaces as direct
parents to allow use of invokespecial for super calls.
```
> ;scalac sandbox/test.scala ; scala Test
[info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test
T
C
[success] Total time: 2 s, completed 04/05/2016 11:07:13 AM
> eval "javap -classpath . -c -private C".!!
[info] ans: String = Compiled from "test.scala"
[info] public class C implements T {
[info] public C();
[info] Code:
[info] 0: aload_0
[info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V
[info] 4: aload_0
[info] 5: invokespecial #17 // Method T.$init$:()V
[info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$;
[info] 11: ldc #24 // String C
[info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V
[info] 16: aload_0
[info] 17: invokespecial #32 // Method T.foo:()I
[info] 20: pop
[info] 21: return
[info] }
> ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test
[info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test
T
C
[success] Total time: 2 s, completed 04/05/2016 11:07:39 AM
> eval "javap -classpath . -c -private C".!!
[info] ans: String = Compiled from "test.scala"
[info] public class C implements T {
[info] public C();
[info] Code:
[info] 0: aload_0
[info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V
[info] 4: aload_0
[info] 5: invokestatic #18 // Method T.$init$:(LT;)V
[info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$;
[info] 11: ldc #25 // String C
[info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V
[info] 16: aload_0
[info] 17: invokestatic #33 // Method T.foo:(LT;)I
[info] 20: pop
[info] 21: return
[info] }
> eval "javap -classpath . -c -private T".!!
[info] ans: String = Compiled from "test.scala"
[info] public interface T {
[info] public static int foo(T);
[info] Code:
[info] 0: iconst_0
[info] 1: ireturn
[info]
[info] public int foo();
[info] Code:
[info] 0: aload_0
[info] 1: invokestatic #15 // Method foo:(LT;)I
[info] 4: ireturn
[info]
[info] public static void $init$(T);
[info] Code:
[info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$;
[info] 3: ldc #25 // String T
[info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V
[info] 8: return
[info]
[info] public void $init$();
[info] Code:
[info] 0: aload_0
[info] 1: invokestatic #32 // Method $init$:(LT;)V
[info] 4: return
[info] }
```
retronym
pushed a commit
that referenced
this pull request
Aug 20, 2020
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