[jdk16] RFR: 8261310: PPC64 Zero build fails with 'VMError::controlled_crash(int)::FunctionDescriptor functionDescriptor' has incomplete type and cannot be defined

[Aleksey Shipilev]

On Mon, 8 Feb 2021 10:33:48 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> $ CONF=linux-ppc64-zero-fastdebug make hotspot
>> 
>> 
>>  1799 | struct FunctionDescriptor functionDescriptor;
>>       | ^~~~~~~~~~~~~~~~~~
>> 
>> `FunctionDescriptor` is from `src/hotspot/cpu/ppc/assembler_ppc.hpp`, and obviously not available for Zero.
>> 
>> The affected code was removed by JDK-8252148 in 17, so this issue affects versions below it.
>> While not exactly the regression for 16, it would be nice to have this fixed for 16 and lower, to get clean builds on all platform configurations, including JDK 16 GA.
>> 
>> The fix is trivial:
>> 
>> diff --git a/src/hotspot/share/utilities/vmError.cpp b/src/hotspot/share/utilities/vmError.cpp
>> index 9b0dc413bcd..476fdc48e43 100644
>> --- a/src/hotspot/share/utilities/vmError.cpp
>> +++ b/src/hotspot/share/utilities/vmError.cpp
>> @@ -1795,7 +1795,7 @@ void VMError::controlled_crash(int how) {
>>    char * const dataPtr = NULL; // bad data pointer
>>    const void (*funcPtr)(void); // bad function pointer
>>  
>> -#if defined(PPC64) && !defined(ABI_ELFv2)
>> +#if defined(PPC64) && !defined(ABI_ELFv2) && !defined(ZERO)
>>    struct FunctionDescriptor functionDescriptor;
>>  
>>    functionDescriptor.set_entry((address) 0xF);
>> 
>> Additional testing:
>>  - [x] Linux Zero PPC64 fastdebug build
>
> This is trivial and fine. 
> 
> The way it is fixed may trip error handler tests on Zero which test that the pc is correctly displayed. But I don't think we have such a test. We have downstream but I ever brought it upstream. Its also not terribly important.
> 
> Also, function descriptors should be available with zero too of course, but I'm not sure its worth following up on that. Note that one could just do:
>   void* fakefundes[2] = { 0xF, NULL };
>   funcPtr = (const void(*)()) &fakefundes;
> and it would probably work just fine.
> 
> Cheers, Thomas

Retargeted to 16u: https://github.com/openjdk/jdk16u/pull/23

-------------

PR: https://git.openjdk.java.net/jdk16/pull/147