[foreign-memaccess+abi] RFR: 8291826: Rework MemoryLayout Sealed Hierarchy [v10]
Per Minborg
duke at openjdk.org
Wed Aug 24 09:09:02 UTC 2022
> This PR is a significant refactor of the `MemoryLayout` sealed hierarchy and whose purpose is described more in detail in https://bugs.openjdk.org/browse/JDK-8291826. In short, the main purpose is to allow pattern matching.
>
> The objective of the PR is to fix the issues described above while retaining as much API compatibility as possible with the pre-PR API. No changes were needed in any of the existing tests for example.
>
> The old sealed hierarchy prevented pattern matching with totality from being used and implied a number of other problems as illustrated in the picture below:
>
> ![graphviz (33)](https://user-images.githubusercontent.com/7457876/185412743-febeb3cf-aebc-4e2e-b78f-3b8ef87b0510.png)
>
> Red nodes cannot be used in pattern matching. Light red nodes are implementations that are visible in the API. White nodes are interfaces.
>
> After this PR has been integrated, an improved sealed hierarchy will exist as depicted here:
>
> ![graphviz (34)](https://user-images.githubusercontent.com/7457876/185413448-8435b23f-5ac4-4999-8b0a-0d6051a0d9be.png)
>
> Gray "Impl" nodes are internal and not exported by the `java.base` module. White nodes are interfaces.
>
> Below, the "Principal Totalities" for the new API are outlined:
>
>
> var v0 = switch (memoryLayout) {
> case MemoryLayout ml -> 0;
> };
> var v1 = switch (memoryLayout) {
> case GroupLayout gl -> 0;
> case PaddingLayout pl -> 0; // leaf
> case SequenceLayout sl -> 0; // leaf
> case ValueLayout vl -> 0;
> };
> var v2 = switch (memoryLayout) {
> case PaddingLayout pl -> 0; // leaf
> case SequenceLayout sl -> 0; // leaf
> case ValueLayout vl -> 0;
> case StructLayout sl -> 0; // leaf
> case UnionLayout ul -> 0; // leaf
> };
> var v3 = switch (memoryLayout) {
> case PaddingLayout pl -> 0; // leaf
> case SequenceLayout sl -> 0; // leaf
> case StructLayout sl -> 0; // leaf
> case UnionLayout ul -> 0; // leaf
> case OfAddress oa -> 0; // leaf
> case OfBoolean ob -> 0; // leaf
> case OfByte ob -> 0; // leaf
> case OfChar oc -> 0; // leaf
> case OfDouble od -> 0; // leaf
> case OfFloat of -> 0; // leaf
> case OfInt oi -> 0; // leaf
> case OfLong ol -> 0; // leaf
> case OfShort os -> 0; // leaf
> };
> var v4 = switch (memoryLayout) {
> case GroupLayout gl -> 0;
> case PaddingLayout pl -> 0; // leaf
> case SequenceLayout sl -> 0; // leaf
> case OfAddress oa -> 0; // leaf
> case OfBoolean ob -> 0; // leaf
> case OfByte ob -> 0; // leaf
> case OfChar oc -> 0; // leaf
> case OfDouble od -> 0; // leaf
> case OfFloat of -> 0; // leaf
> case OfInt oi -> 0; // leaf
> case OfLong ol -> 0; // leaf
> case OfShort os -> 0; // leaf
> };
>
>
>
> Additional improvements can be made later in a separate PR, including removing/improving some of the internal abstract classes.
Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
Fix constructor calls
-------------
Changes:
- all: https://git.openjdk.org/panama-foreign/pull/710/files
- new: https://git.openjdk.org/panama-foreign/pull/710/files/f8781a41..5c554984
Webrevs:
- full: https://webrevs.openjdk.org/?repo=panama-foreign&pr=710&range=09
- incr: https://webrevs.openjdk.org/?repo=panama-foreign&pr=710&range=08-09
Stats: 9 lines in 1 file changed: 0 ins; 0 del; 9 mod
Patch: https://git.openjdk.org/panama-foreign/pull/710.diff
Fetch: git fetch https://git.openjdk.org/panama-foreign pull/710/head:pull/710
PR: https://git.openjdk.org/panama-foreign/pull/710
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