8258272: LoadVectorMaskedNode can't be replaced by zero con

[neliasso]

A test fails for this code:

byte [] src = new byte[0];
byte [] dest = Arrays::copy_of(src);

This is transformed to something like:
byte [] src = new byte[0];
byte [] dest = new byte[0];
System.arraycopy(src, 0, dest, 0, src.lenght());

This causes a problem in LoadNode::Value for the new LoadVectorMasked nodes. LoadNode::Value sees that the load will always load a zero - and will try to replace itself with a zero constant. That doesn't work for the LoadVectorMaskedNodes currently.

This patch adds a check to the zero-optimization to pass on vector types.

This patch is currently missing a new test. Since we are nearing the end of bugfixing in JDK16 I decided to publish the fix first so that any discussion of the fix can be had now.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8258272: LoadVectorMaskedNode can't be replaced by zero con

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)
• Vladimir Ivanov (@iwanowww - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk16 pull/105/head:pull/105
$ git checkout pull/105

[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 02: Full - Incremental (b50b737)
• 01: Full - Incremental (6150533)
• 00: Full (0fb4aab)

[chhagedorn]

That looks good to me!

[openjdk]

@neliasso This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8258272: LoadVectorMaskedNode can't be replaced by zero con

Reviewed-by: chagedorn, vlivanov

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 71 new commits pushed to the master branch:

• 417e1d1: 8259061: C2: assert(found) failed: memory-writing node is not placed in its original loop or an ancestor of it
• 793017d: 8259601: AArch64: Fix reinterpretX2D match rule issue
• 15dd8f3: 8259275: JRuby crashes while resolving invokedynamic instruction
• 1cf2378: 8259353: VectorReinterpretNode is incorrectly optimized out
• 17b4db3: 8259636: Check for buffer backed by shared segment kicks in in unexpected places
• 5f9cd72: 8259645: Revert JDK-8245956 JavaCompiler still uses File API instead of Path API in a specific case
• b03880e: 8259634: MemorySegment::asByteBuffer does not respect spatial bounds
• 8a81cf1: 8259298: broken link in Stream::toList spec
• 67e1b63: 8259380: Correct pretouch chunk size to cap with actual page size
• 28ff2de: 8259237: Demo selection changes with left/right arrow key. No need to press space for selection.
• ... and 61 more: https://git.openjdk.java.net/jdk16/compare/61390d8e452058efe00ca8ce833baa879fbb9c9e...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[iwanowww]

Looks good.

[chhagedorn]

Looks good!

[iwanowww]

Even better!

[neliasso]

/integrate

[openjdk]

@neliasso Since your change was applied there have been 73 commits pushed to the master branch:

• a99df45: 8259560: Zero m68k: "static assertion failed: align" after JDK-8252049
• efc36be: 8258985: Parallel WeakProcessor may use too few threads
• 417e1d1: 8259061: C2: assert(found) failed: memory-writing node is not placed in its original loop or an ancestor of it
• 793017d: 8259601: AArch64: Fix reinterpretX2D match rule issue
• 15dd8f3: 8259275: JRuby crashes while resolving invokedynamic instruction
• 1cf2378: 8259353: VectorReinterpretNode is incorrectly optimized out
• 17b4db3: 8259636: Check for buffer backed by shared segment kicks in in unexpected places
• 5f9cd72: 8259645: Revert JDK-8245956 JavaCompiler still uses File API instead of Path API in a specific case
• b03880e: 8259634: MemorySegment::asByteBuffer does not respect spatial bounds
• 8a81cf1: 8259298: broken link in Stream::toList spec
• ... and 63 more: https://git.openjdk.java.net/jdk16/compare/61390d8e452058efe00ca8ce833baa879fbb9c9e...master

Your commit was automatically rebased without conflicts.

Pushed as commit 5567530.

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