8374113: Taughtological if check in Reflection::array_set

[stefank]

While reviewing code in the Valhalla repository I saw that Reflection::array_set has this funny-looking code:

  if (a->is_objArray()) {
    if (value_type == T_OBJECT) {
    ...
    } // what happens in the else case? here
  } else {
    assert(a->is_typeArray(), "just checking");
  }

And wondered what would happen if the value_type == T_OBJECT check failed, and how is this handled with flattened arrays, given that we have T_FLAT_ELEMENT there.

It turns out that the calling code passes down T_OBJECT even for flat arrays so they do take the value_type == T_OBJECT path, so that's fine.

So, I propose that we just replace one of the ifs with an assert.

---

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Issue

• JDK-8374113: Taughtological if check in Reflection::array_set (Enhancement - P4)

Reviewers

• Frederic Parain (@fparain - Reviewer)
• Chen Liang (@liach - Reviewer)

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8374113: Taughtological if check in Reflection::array_set

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• 6c9999c: 8373984: Check for macos 11 in CGraphicsDevice.m can be removed
• dca55b4: 8371420: Still sporadic failures of gc/TestAlwaysPreTouchBehavior.java# on Linux after JDK-8359104
• b5ac8f8: 8373246: JDK-8351842 broke native debugging on Linux
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[stefank]

Tier1 testing passes

[fparain]

LGTM

[liach]

This one seems safe because this seems only used by Array.set and the primitive overloads. I checked JVM_SetArrayElement and JVM_SetPrimitiveArrayElement callers in Array.c. However note that java.lang.reflect.Array is poorly tested/covered, so please help check if there are other sites that can pass in inconsistent array oop + value type.

[stefank]

This one seems safe because this seems only used by Array.set and the primitive overloads. I checked JVM_SetArrayElement and JVM_SetPrimitiveArrayElement callers in Array.c. However note that java.lang.reflect.Array is poorly tested/covered, so please help check if there are other sites that can pass in inconsistent array oop + value type.

Thanks for taking a look at this!

There are no other callers to Reflection::array_set. And if there are future additions that are problematic then those should be found by the added assert.

[liach]

Looks good from core reflection POV.