RFR: 8298720: Insufficient error handling when CodeBuffer is exhausted

[Tobias Hartmann]

On Wed, 4 Jan 2023 09:06:44 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> This patch fixes various places in C1 and C2 on Aarch64 and RISC-V that miss proper error handling when the code buffer is exhausted, leading to crashes. Similar but incomplete patches went in with [JDK-8130309](https://bugs.openjdk.org/browse/JDK-8130309), [JDK-8248411](https://bugs.openjdk.org/browse/JDK-8248411) and [JDK-8272094](https://bugs.openjdk.org/browse/JDK-8272094) in the past. 
>> 
>> These issues are extremely hard to reproduce, even with the `-XX:+StressCodeBuffers` option, because code buffer expansion needs to fail at the exact moment when a specific (unhandled) instruction is emitted. Even with the stress option, we expand the code buffer such that multiple instructions will fit and in addition, chances are high that we simply bail out from compilation before emitting the problematic instruction. I attached a patch to [JDK-8298720](https://bugs.openjdk.org/browse/JDK-8298720), that makes `-XX:+StressCodeBuffers` randomized and more aggressive. With that, I can reproduce the issue reliably but it's extremely slow and therefore not well suited for integration.
>> 
>> I now went over all usages of `CodeBuffer::expand` to make sure that we have proper error handling in place and found some remaining issues in JVMCI code. I filed [JDK-8299570](https://bugs.openjdk.org/browse/JDK-8299570) to address them.
>> 
>> I would need help to test the RISC-V specific changes.
>> 
>> Thanks,
>> Tobias
>
> Hi! Thanks for handling RISC-V at the same time. I can help arrange some necessary tests on linux-riscv64 for those changes.

Thanks @RealFYang! It's mostly about verifying that I did not miss any label in the `reset_labels` calls. You should be able to hardcode the bailout to always true and check if we don't hit any assert.

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PR: https://git.openjdk.org/jdk/pull/11839