8293833: Error mixing types with -XX:+UseCMoveUnconditionally -XX:+UseVectorCmov

[fg1417]

After JDK-8139340, JDK-8192846 and JDK-8289422, we can vectorize the case below by enabling -XX:+UseCMoveUnconditionally and -XX:+UseVectorCmov:

// double[] a, double[] b, double[] c;
for (int i = 0; i < a.length; i++) {
    c[i] = (a[i] > b[i]) ? a[i] : b[i];
}

But we don't support the case like:

// double[] a;
// int seed;
for (int i = 0; i < a.length; i++) {
    a[i] = (i % 2 == 0) ? seed + i : seed - i;
}

because the IR nodes for the CMoveD in the loop is:

  AddI  AndI     AddD   SubD
     \  /         /     /
     CmpI        /    /
       \        /   /
      Bool     /  /
          \   / /
          CMoveD

and it is not our target pattern, which requires that the inputs of Cmp node must be the same as the inputs of CMove node as commented in CMoveKit::make_cmovevd_pack(). Because we can't vectorize the CMoveD pack, we shouldn't vectorize its inputs, AddD and SubD. But the current function CMoveKit::make_cmovevd_pack() doesn't clear the unqualified CMoveD pack from the packset. In this way, superword wrongly vectorizes AddD and SubD. Finally, we get a scalar CMoveD node with two vector inputs, AddVD and SubVD, which has wrong mixing types, then the assertion fails.

To fix it, we need to remove the unvectorized CMoveD pack from the packset and clear related map info.

---

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Issue

• JDK-8293833: Error mixing types with -XX:+UseCMoveUnconditionally -XX:+UseVectorCmov

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)

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[merykitty]

May I ask if we can vectorise Bool -> Cmp into VectorMaskCmp and CMove into VectorBlend, this would help vectorise the pattern you mention in the description instead of bailing out? Thanks.

[fg1417]

May I ask if we can vectorise Bool -> Cmp into VectorMaskCmp and CMove into VectorBlend, this would help vectorise the pattern you mention in the description instead of bailing out? Thanks.

@merykitty Thanks for your kind review and question.

That's really an interesting idea. IMO, vectorizing Bool -> Cmp and CMove separately, to support more cases, deserves a deep investigation. I'm not sure if it's feasible. But for the case in the description, even trying the idea, we still can't vectorize the case because we can't vectorize i % 2 currently. In this way, we can't vectorize any chain involving i % 2.

[openjdk[bot]]

@fg1417 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:

8293833: Error mixing types with -XX:+UseCMoveUnconditionally -XX:+UseVectorCmov

Reviewed-by: chagedorn, kvn

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 96 new commits pushed to the master branch:

• 529cc48f355523fd162470b416a5081869adcf0e: 8295396: RISC-V: Cleanup useless CompressibleRegions
• 692cdab2be7dfc6e12b127f8e2c97bc41536cb84: 8295016: Make the arraycopy_epilogue signature consistent with its usage
• 21a825e059170e3a069b9f0982737c5839e6dae2: 8288387: GetLocalXXX/SetLocalXXX spec should require suspending target thread
• 8d751de3198675b22704cdccafaff2fc0fdd3f59: 8295231: Move all linking of native libraries to make
• f300ec8631b781938e6e96165ba23cda14a20f24: 8294546: document where javac differs when invoked via launcher and ToolProvider
• b269c51d10c353d9b7143b2239beb23c01352182: 8295395: Linux Alpha Zero builds fail after JDK-8292591
• ae60599e2ba75d80c3b4279903137b2c549f8066: 8295023: Interpreter(AArch64): Implement -XX:+PrintBytecodeHistogram and -XX:+PrintBytecodePairHistogram options
• 4d37ef2d545c016e6c3ad52171ea961d4406726f: 8295262: Build binutils out of source tree
• 0919a3a0c198a5234b5ed9a3bb999564d2382a56: 8294186: AArch64: VectorMaskToLong failed on SVE2 machine with -XX:UseSVE=1
• ec2981b83bc3ef6977b5f16d5222eb49b0ea49ad: 8293711: Factor out size parsing functions from arguments.cpp
• ... and 86 more: https://git.openjdk.org/jdk/compare/97f1321cb455b536f1e4e056dec693c24f39d641...master

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[fg1417]

@chhagedorn thanks for your review and comments! I updated the commit to resolve the code style issue.

[fg1417]

Thanks for the update, looks good and testing passed!

@chhagedorn thanks for your review and test work!

[fg1417]

Does compiler/c2/irTests/TestVectorConditionalMove.java IR test cover this case? Can you add it if it is not already?

Thanks for pointing it out @vnkozlov . Updated the IR testcase in the new commit.

[fg1417]

Thanks all for your review and comments. I'll integrate it.

/integrate

[openjdk[bot]]

@fg1417 Your change (at version f65118cc7f5088cfbf164eed8cf676fc6dd8548c) is now ready to be sponsored by a Committer.

[nsjian]

/sponsor

[openjdk[bot]]

Going to push as commit 490fcd0c2547cb4e564363f0cd121c777c3acc02. Since your change was applied there have been 96 commits pushed to the master branch:

• 529cc48f355523fd162470b416a5081869adcf0e: 8295396: RISC-V: Cleanup useless CompressibleRegions
• 692cdab2be7dfc6e12b127f8e2c97bc41536cb84: 8295016: Make the arraycopy_epilogue signature consistent with its usage
• 21a825e059170e3a069b9f0982737c5839e6dae2: 8288387: GetLocalXXX/SetLocalXXX spec should require suspending target thread
• 8d751de3198675b22704cdccafaff2fc0fdd3f59: 8295231: Move all linking of native libraries to make
• f300ec8631b781938e6e96165ba23cda14a20f24: 8294546: document where javac differs when invoked via launcher and ToolProvider
• b269c51d10c353d9b7143b2239beb23c01352182: 8295395: Linux Alpha Zero builds fail after JDK-8292591
• ae60599e2ba75d80c3b4279903137b2c549f8066: 8295023: Interpreter(AArch64): Implement -XX:+PrintBytecodeHistogram and -XX:+PrintBytecodePairHistogram options
• 4d37ef2d545c016e6c3ad52171ea961d4406726f: 8295262: Build binutils out of source tree
• 0919a3a0c198a5234b5ed9a3bb999564d2382a56: 8294186: AArch64: VectorMaskToLong failed on SVE2 machine with -XX:UseSVE=1
• ec2981b83bc3ef6977b5f16d5222eb49b0ea49ad: 8293711: Factor out size parsing functions from arguments.cpp
• ... and 86 more: https://git.openjdk.org/jdk/compare/97f1321cb455b536f1e4e056dec693c24f39d641...master

Your commit was automatically rebased without conflicts.

[openjdk[bot]]

@nsjian @fg1417 Pushed as commit 490fcd0c2547cb4e564363f0cd121c777c3acc02.

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