RFR: 8283643: [AIX, testbug] MachCodeFramesInErrorFile test fails to find 'Native frames' text

[Tyler Steele]

On Wed, 20 Apr 2022 05:49:15 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> I observed a failure of MachCodeFramesInErrorFile.java on AIX. The raised error complains that 'Native frames: ' is missing. To fix the failure, I made two changes to the test that allowed it to pass on AIX.
>> 
>> The first change made was to the test's `extractFrames` method. AIX overrides `os::platform_print_native_stack` with stack printing specific to AIX/Power. This code does not produce the 'Native frames: ' text that `vmError::print_native_stack` does, so the test was modified to expect the AIX output when run on AIX. 
>> 
>> A second change was made to the address passed to the `crashInNative1` method. AIX does not consider low-address memory to be protected as other platforms do. In fact, "the first 256 bytes are reserved for software use" according to the Power ISA. Accordingly, the read address for PPC was changed to -1 (0xFF..FF) to produce the expected failure result.
>> 
>> ### Testing
>> 
>> Tier1 tests complete as expected on AIX/Power.
>
> BTW, feel free to tweak the native stack printing on os_aix.cpp to print "Native" etc like the other variants do. It is just cosmetics, and the less AIX specifics in shared code the better.
> 
> Thanks for taking care of this!

Thanks for your suggestions @tstuefe. Your comments suggest a different tack than I originally took with this change, so I converted this to a draft while I test out those ideas.

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PR: https://git.openjdk.java.net/jdk/pull/8094