On Mon, 6 Feb 2023 07:05:39 GMT, Hao Sun <hao...@openjdk.org> wrote:
>> src/hotspot/cpu/aarch64/vm_version_aarch64.cpp line 413:
>>
>>> 411: }
>>> 412:
>>> 413: if (UseBranchProtection == nullptr || strcmp(UseBranchProtection,
>>> "none") == 0) {
>>
>> My understanding is that `UseBranchProtection` requires JIT compiler
>> integration. This is currently missing in Graal. The logic that decides if
>> it should be enabled by default needs to take JVMCI into consideration, much
>> like the call to `JVMCIGlobals::check_jvmci_supported_gc` determines if
>> JVMCI supports the configured GC.
>>
>> Thanks to @gilles-duboscq for alerting me to this change.
>
> Thanks for reporting this. @dougxc
>
> Yes. I encountered several jtreg failures with Graal, which is built with
> PAC-RET enabled JDK.
>
> As I see it, the straightforward fix is to disable JVMCI if `_rop_protection`
> is parsed as "true" finally, since Graal doesn't supports PAC-RET currently.
> That is similar to the way `JVMCIGlobals::check_jvmci_supported_gc` does,
> i.e. if one GC except `G1/Serial/Parallel` is configured, we disable JVMCI.
> WDYT
The problem with `JVMCIGlobals::check_jvmci_supported_gc` is that it does not
give the compiler a chance to specify whether it supports a given GC.
Instead, we want a JVMCI upcall like
`jdk.vm.ci.hotspot.HotSpotJVMCIRuntime.isGCSupported(int)`.
-------------
PR: https://git.openjdk.org/jdk/pull/6334
