[jdk8u-dev] RFR: 8250825: C2 crashes with assert(field != __null) failed: missing field [v2]

[SendaoYan]

On Wed, 28 Aug 2024 03:19:32 GMT, SendaoYan <syan at openjdk.org> wrote:

>> hotspot/src/share/vm/opto/type.cpp line 2561:
>> 
>>> 2559:             BasicType basic_elem_type = field->layout_type();
>>> 2560:             _is_ptr_to_narrowoop = UseCompressedOops && (basic_elem_type == T_OBJECT ||
>>> 2561:                                                        basic_elem_type == T_ARRAY);
>> 
>> This line hasn't been adjusted to line up with the one above.
>> 
>> Are you not backporting from the 11u patch? That also doesn't have JDK-8230505 and would match your patch exactly if not for this misaligned line.
>> 
>> This is the 11u version:
>> 
>> ~~~
>> -          assert(field != NULL, "missing field");
>> -          BasicType basic_elem_type = field->layout_type();
>> -          _is_ptr_to_narrowoop = UseCompressedOops && (basic_elem_type == T_OBJECT ||
>> -                                                       basic_elem_type == T_ARRAY);
>> +          if (field != NULL) {
>> +            BasicType basic_elem_type = field->layout_type();
>> +            _is_ptr_to_narrowoop = UseCompressedOops && (basic_elem_type == T_OBJECT ||
>> +                                                         basic_elem_type == T_ARRAY);
>> +          } else {
>> +            // unsafe access
>> +            _is_ptr_to_narrowoop = UseCompressedOops;
>> +          }
>> ~~~
>
> No, I was backported from jdk trunk repo. But I think line 2561 is not misaligned line, it just a github code display style issue. The below screenshot can explain the difference. The left side shows this PR change, the right side shows the jdk11u-dev change of JDK-8250825. I think the change is equivalent.
> 
> ![image](https://github.com/user-attachments/assets/479e94da-7984-4d8a-9b2c-5a6832e5c2e2)

Backport from jdk11u-dev to jdk8u-dev is more reasonable and exactly than from jdk trunk. I will pay attention for that.

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PR Review Comment: https://git.openjdk.org/jdk8u-dev/pull/552#discussion_r1733926318