RFR: 8255718: Zero: VM should know it runs in interpreter-only mode

[Aleksey Shipilev]

On Mon, 2 Nov 2020 23:03:09 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> There are many tests in tier1 that fail with Zero, because they supply -XX:+TieredCompilation, and that makes VM code believe it runs in "mixed" mode. 
>> 
>> Can be reproduced trivially by running anything with -XX:+TieredCompilation. Then Zero fails when runtime asks it to produce a native wrapper for MH intrinsics. That code is normally protected by Arguments::is_interpreter_only.
>> 
>> Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
>>                                                        Symbol* signature,
>>                                                        TRAPS) {
>>     ...
>>     if (!Arguments::is_interpreter_only()) {  // <--- checks here
>>       // Generate a compiled form of the MH intrinsic.
>>       AdapterHandlerLibrary::create_native_wrapper(m); // <--- fails through here
>>     }
>> 
>> Then in `sharedRuntime_zero.cpp`:
>> 
>> nmethod *SharedRuntime::generate_native_wrapper(MacroAssembler *masm,
>>                                                 const methodHandle& method,
>>                                                 int compile_id,
>>                                                 BasicType *sig_bt,
>>                                                 VMRegPair *regs,
>>                                                 BasicType ret_type,
>>                                                 address critical_entry) {
>>   ShouldNotCallThis();  // <--- crashes here
>>   return NULL;
>> }
>> 
>> ...so:
>> 
>> $ build/linux-x86_64-zero-fastdebug/images/jdk/bin/java -XX:+TieredCompilation 
>> OpenJDK 64-Bit Zero VM warning: -XX:+TieredCompilation not supported in this VM
>> # To suppress the following error report, specify this argument
>> # after -XX: or in .hotspotrc:  SuppressErrorAt=/sharedRuntime_zero.cpp:80
>> #
>> # A fatal error has been detected by the Java Runtime Environment:
>> #
>> #  Internal Error (/home/shade/trunks/jdk/src/hotspot/cpu/zero/sharedRuntime_zero.cpp:80), pid=404967, tid=404968
>> #  Error: ShouldNotCall()
>> 
>> Additional testing:
>>  - [x] ad-hoc Hello World runs with Linux x86_64 Zero
>>  - [x] re-run some failed `tier1` tests with Linux x86_64 Zero, now passing
>
> Looks good. Thank you for taking care of Zero.

Thank you for reviews.

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

PR: https://git.openjdk.java.net/jdk/pull/985