RFR: 8302459: Missing late inline cleanup causes compiler/vectorapi/VectorLogicalOpIdentityTest.java IR failure [v3]
Damon Fenacci
dfenacci at openjdk.org
Fri Feb 28 13:37:13 UTC 2025
> # Issue
>
> The `compiler/vectorapi/VectorLogicalOpIdentityTest.java` has been failing because C2 compiling the test `testAndMaskSameValue1` expects to have 1 `AndV` nodes but it has none.
>
> # Cause
>
> The issue has to do with the criteria that trigger a cleanup when performing late inlining. In the failing test, when the compiler tries to inline a `jdk.internal.vm.vector.VectorSupport::binaryOp` call, it fails because its argument is of the wrong type, mainly because some cast nodes “hide” the more “precise” type.
> The graph that leads to the issue looks like this:
> 
> The compiler tries to inline `jdk.internal.vm.vector.VectorSupport::load` and it succeeds:
> 
> The node `3027 VectorBox` has type `IntMaxVector`. `912 CastPP` and `934 CheckCastPP` have type `IntVector`instead.
> The compiler then tries to inline one of the 2 `bynaryOp` calls but it fails because it needs an argument of type `IntMaxVector` and the argument it is given, which is node `934 CheckCastPP` , has type `IntVector`.
>
> This would not happen if between the 2 inlining attempts a _cleanup_ was triggered. IGVN would run and the 2 nodes `912 CastPP` and `934 CheckCastPP` would be folded away. `binaryOp` could then be inlined since the types would match.
>
> # Solution
>
> Instead of fixing this specific case we try a more generic approach: when late inlining we keep track of failed intrinsics and re-examine them during IGVN. If the `Ideal` method for their call node is called, we reschedule the intrinsic attempt for that call.
>
> # Testing
>
> Additional test runs with `-XX:-TieredCompilation` are added to `VectorLogicalOpIdentityTest.java` and `VectorGatherMaskFoldingTest.java` as regression tests and `-XX:+IncrementalInlineForceCleanup` is removed from `VectorGatherMaskFoldingTest.java` (previously added as workaround for this issue)
>
> Tests: Tier 1-4 (windows-x64, linux-x64/aarch64, and macosx-x64/aarch64; release and debug mode)
Damon Fenacci has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 40 commits:
- JDK-8302459: unneeded changes
- JDK-8302459: unneeded changes
- JDK-8302459: update assert string
- JDK-8302459: fix copyright year
- JDK-8302459: fix after merge
- Merge branch 'master' into JDK-8302459-new
- JDK-8302459: add logging
- JDK-8302459: remove todos
- JDK-8302459: add check to avoid infinite loop
- Merge branch 'master' into JDK-8302459-new
- ... and 30 more: https://git.openjdk.org/jdk/compare/a637ccf2...e71e72f5
-------------
Changes: https://git.openjdk.org/jdk/pull/21682/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21682&range=02
Stats: 89 lines in 6 files changed: 36 ins; 3 del; 50 mod
Patch: https://git.openjdk.org/jdk/pull/21682.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/21682/head:pull/21682
PR: https://git.openjdk.org/jdk/pull/21682
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