[lworld] RFR: 8242612: [lworld] Javac should not expressly encode the new super interface types in class files

[Jim Laskey]

On Mon, 18 May 2020 12:14:23 GMT, Srikanth Adayapalam <sadayapalam at openjdk.org> wrote:

> Jim, Could you please review this change ? TIA.
> 
> Changes:
> 
>     - Withdraw the new top type InlineObject (per design)
>     - Do not encode the new top types in class files as this is noisy and
>       very disruptive and let the static compiler and the dynamic environments
>       inject these types as needed. (since classes compiled with legacy compilers
>       will not encode these top types anyway the VM has to resort to injection,
>       why not resort to injection for everything is the motivation)
>     - Adjust some code that is surprised by super interfaces being empty.
> 
> More background is available in https://bugs.openjdk.java.net/browse/JDK-8242612

Changes requested by jlaskey (no project role).

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Symtab.java line 276:

> 275:                         Type it;
> 276:                         if (ct.interfaces_field == null || ct.interfaces_field.isEmpty()) {
> 277:                             it = objectType;

I'm assuming that you are using this to indicate no top interfaces. Is this safe (non-hackish)?

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java line 2526:

> 2525:                     ClassType ct = (ClassType) qualifierType;
> 2526:                     if (ct.interfaces_field == null || ct.interfaces_field.isEmpty()) {
> 2527:                         wcb = syms.objectType;

Same - maybe define a predicate for this.

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PR: https://git.openjdk.java.net/valhalla/pull/50