hg: valhalla/valhalla: Scanner, parser, semantic analysis and attribution support for value types

[Srikanth]

Hello,

The commit below is the record of the change set I pushed to valhalla 
"exp" branch
that contains the javac changes for scanner, parser, semantic analysis 
and attribution
support for value types. Most of this is leveraged from the existing 
prototype
and tweaked for the present work.

No code generation support exists at the moment. I will look into it now.
See below for the summary of changes and a couple of questions.

Summary of changes:

     - Tag a type declaration as being a value type with __ByValue 
modifier (>= JDK11)
     - Value types may not declare a super class not even j.l.O
     - Value class declarations and their instance fields must be final.
     - Value types may not declare fields of their own types either 
directly or indirectly.
     - Null cannot be assigned to value types
     - Null cannot be casted to or compared with value types.
     - Support for static value factories and value instance creation 
via __MakeDefault()
     - Values have no instance lock and so may not be synchronized upon.
     - Values have no identity and consequently the method 
java.lang.System.identityHashCode
       may not be invoked on them and
     - The following methods from j.l.O are not allowed on value receivers:
         - clone()
         - finalize()
         - wait()
         - wait(long),
         - wait(long, int)
         - notify
         - notifyAll
     - Value instances may not be compared with == or !=
     - Tests for the above restrictions.

Questions:

1.    ATM, javac forbids comparison of values using != or ==. This 
behavior is simply
brought forward from the original valhalla implementation. Is this what 
we want in
the present prototype ? (in the context of acmp performance 
characterization ?)

2. The support in the parser allows inner class to be declared as 
__ByValue. Do we want
to restrict values to top level classes ? I seem to recall this being 
suggested a while
ago - but I am unable to dig up the context.

Thanks!
Srikanth


On Tuesday 30 January 2018 02:49 PM, srikanth.adayapalam at oracle.com wrote:
> Changeset: 8d76e47a91e7
> Author:    sadayapalam
> Date:      2018-01-30 14:45 +0530
> URL:       http://hg.openjdk.java.net/valhalla/valhalla/rev/8d76e47a91e7
>
> Scanner, parser, semantic analysis and attribution support for value types
>
> ! src/java.compiler/share/classes/javax/lang/model/element/Modifier.java
> ! src/jdk.compiler/share/classes/com/sun/source/tree/NewClassTree.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Flags.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Source.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/MemberEnter.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/parser/Tokens.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/tree/JCTree.java
> ! src/jdk.compiler/share/classes/com/sun/tools/javac/util/Names.java
> ! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/Utils.java
> ! src/jdk.jshell/share/classes/jdk/jshell/CompletenessAnalyzer.java
> ! test/langtools/tools/javac/diags/examples.not-yet.txt
> + test/langtools/tools/javac/diags/examples/ValuesNotSupported.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckClone.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckClone.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckCyclicMembership.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckCyclicMembership.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckEquals.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckEquals.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckExtends.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckExtends.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckFinal.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckFinal.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckFinalize.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckFinalize.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckIdentityHash.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckIdentityHash.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckIdentityHash01.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckIdentityHash01.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckMakeDefault.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckMakeDefault.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckNullAssign.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckNullAssign.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckNullCastable.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckNullCastable.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckStaticValueFactory.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckStaticValueFactory.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckSuperCompileOnly.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckSync.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckSync.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckSynchronized.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckSynchronized.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckValueFactoryWithReference.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckValueFactoryWithReference.out
> + test/langtools/tools/javac/valhalla/lworld-values/CheckValueModifier.java
> + test/langtools/tools/javac/valhalla/lworld-values/CheckValueModifier.out
> + test/langtools/tools/javac/valhalla/lworld-values/Point.java
>