[jdk18] RFR: 8272058: 25 Null pointer dereference defect groups in 4 files [v5]

[Daniel D.Daugherty]

On Wed, 19 Jan 2022 12:01:17 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> I wondered if target_addr_for_insn ever gets the ldrw_to_zr instruction. 
>> Anyway, I am Ok to move it to target_addr_for_insn_allow_null_ret (target_addr_for_insn_or_null?).
>> Thank you.
>
>> @bulasevich - I've made another pass through the code and checked the calls to `MacroAssembler::target_addr_for_insn()` and I don't see any of those calls in areas related to safepoint polling. From the other POV, I took a look at the aarch64 safepoint polling code and I don't see a way into `MacroAssembler::target_addr_for_insn()` .
>> 
>> It is entirely possible that I'm missing something here and would appreciate it if you could sanity check my conclusions here.
> 
> I think you're right. As far as I can see, this code is dead since 
> 8253180: ZGC: Implementation of JEP 376: ZGC: Concurrent Thread-Stack Processing
> 
> which took out the code that generated safepoint relocs, but not the code here that relocated them.

I've filed the following new RFE to track the dead compiler code:

    JDK-8280283 dead compiler code found during the JDK-8272058 code review
    https://bugs.openjdk.java.net/browse/JDK-8280283

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PR: https://git.openjdk.java.net/jdk18/pull/51