8299721: [Vector API] assert in switch-default of LibraryCallKit::arch_supports_vector_rotate is too weak to catch bugs

[DamonFool]

Hi all,

The switch-default path of LibraryCallKit::arch_supports_vector_rotate means runtime error.
This is because lshiftopc@Line136 and rshiftopc@Line137 would be undefined if the switch-default path is taken.

 115   int lshiftopc, rshiftopc;
 116   switch(elem_bt) {
 117     case T_BYTE:
 118       lshiftopc = Op_LShiftI;
 119       rshiftopc = Op_URShiftB;
 120       break;
 121     case T_SHORT:
 122       lshiftopc = Op_LShiftI;
 123       rshiftopc = Op_URShiftS;
 124       break;
 125     case T_INT:
 126       lshiftopc = Op_LShiftI;
 127       rshiftopc = Op_URShiftI;
 128       break;
 129     case T_LONG:
 130       lshiftopc = Op_LShiftL;
 131       rshiftopc = Op_URShiftL;
 132       break;
 133     default:
 134       assert(false, "Unexpected type");
 135   }
 136   int lshiftvopc = VectorNode::opcode(lshiftopc, elem_bt);   <--- lshiftopc is undefine with the default path
 137   int rshiftvopc = VectorNode::opcode(rshiftopc, elem_bt);   <--- rshiftopc is undefine with the default path

So to prevent potential bugs, it would be better to stop and print an error msg even with release VMs, which is done by other switch-default statements in the file.

Thanks.
Best regards,
Jie

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Issue

• JDK-8299721: [Vector API] assert in switch-default of LibraryCallKit::arch_supports_vector_rotate is too weak to catch bugs

Reviewers

• Jatin Bhateja (@jatin-bhateja - Reviewer)

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• 00: Full (6499113f)

[jatin-bhateja]

Rotate operation only works on integral type vectors. But its good to add a fatal msg.
Thanks!

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8299721: [Vector API] assert in switch-default of LibraryCallKit::arch_supports_vector_rotate is too weak to catch bugs

Reviewed-by: jbhateja

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At the time when this comment was updated there had been 2 new commits pushed to the master branch:

• b5b7948: 8298240: Replace the usage of ImageLayoutException by the CMMException
• 99be740: 8299306: Test "javax/swing/JFileChooser/FileSystemView/CustomFSVLinkTest.java" fails on Windows 10 x64 because there are some buttons did not display button name

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[DamonFool]

Rotate operation only works on integral type vectors. But its good to add a fatal msg. Thanks!

Thanks @jatin-bhateja for your quick review.
In real workloads with release VMs, the assert isn't enough to catch the bug since it would just fallback to un-inlined version.
Do you think it is trivial?

[jatin-bhateja]

Rotate operation only works on integral type vectors. But its good to add a fatal msg. Thanks!

Thanks @jatin-bhateja for your quick review. In real workloads with release VMs, the assert isn't enough to catch the bug since it would just fallback to un-inlined version. Do you think it is trivial?

Yes, I agree fatal is correct alternative, your fix look correct, if you see an assertion failure it will be good to capture it in a test.
Best Regards.

[DamonFool]

Yes, I agree fatal is correct alternative, your fix look correct, if you see an assertion failure it will be good to capture it in a test.

Thanks @jatin-bhateja .

We don't have a jtreg test.
It was discovered in our internal weekly code review discussion.
Thanks.

/integrate

[openjdk]

Going to push as commit 8cc1669.
Since your change was applied there have been 6 commits pushed to the master branch:

• 5598acc: 8294403: [REDO] make test should report only on executed tests
• 88f0ea7: 8299726: [cleanup] Some code cleanup in opto/compile.hpp
• 0234f81: 8298447: Unnecessary Vector usage in DocPrintJob implementations
• cc4936a: 8298720: Insufficient error handling when CodeBuffer is exhausted
• b5b7948: 8298240: Replace the usage of ImageLayoutException by the CMMException
• 99be740: 8299306: Test "javax/swing/JFileChooser/FileSystemView/CustomFSVLinkTest.java" fails on Windows 10 x64 because there are some buttons did not display button name

Your commit was automatically rebased without conflicts.

[openjdk]

@DamonFool Pushed as commit 8cc1669.

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