RFR: 8164358: [JVMCI] expose Hotspot intrinsics and HotSpotIntrinsicCandidate info to JVMCI compilers

[Doug Simon]

Hi Christian,

I’ve reformulated the description to clarify why the absence of these features is a bug. I’ll keep this in mind for future.

-Doug

> On 19 Aug 2016, at 17:41, Christian Tornqvist <christian.tornqvist at oracle.com> wrote:
> 
> This issue looks like an RFE and not a bug though? 
> 
> Thanks,
> Christian
> 
> -----Original Message-----
> From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-bounces at openjdk.java.net] On Behalf Of Dmitrij Pochepko
> Sent: Friday, August 19, 2016 11:38 AM
> To: Doug Simon <doug.simon at oracle.com>
> Cc: hotspot compiler <hotspot-compiler-dev at openjdk.java.net>; Christian Thalinger <cthalinger at twitter.com>
> Subject: Re: RFR: 8164358: [JVMCI] expose Hotspot intrinsics and HotSpotIntrinsicCandidate info to JVMCI compilers
> 
> Hi,
> 
> What about tests? Seems like this functionality is not covered by current tests. We might get it broken without noticing in case no tests exists.
> I think at least some sanity test should be added.
> 
> In case tests are added(or already exists) looks good to me (not a reviewer).
> 
> Thanks,
> Dmitrij
> I changed it to only try reuse the declaringClass string (which has the most overlap): http://cr.openjdk.java.net/~dnsimon/8164358v2/ -Doug
>>> On 18 Aug 2016, at 23:59, Doug Simon <doug.simon at oracle.com> wrote:
>>> 
>>> 
>>>> On 18 Aug 2016, at 20:01, Christian Thalinger <cthalinger at twitter.com> wrote:
>>>> 
>>>> src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/
>>>> CompilerToVM.java
>>>> 
>>>>      *         [String name, Long value, ...] vmAddresses,
>>>> 
>>>> +     *         [String name, Long value, ...] vmAddresses,
>>>> 
>>>>      *         VMFlag[] vmFlags
>>>> 
>>>> +     *         VMIntrinsicMethod[] vmIntrinsics
>>>> Looks like a copy-paste problem.
>>> Oops! Will fix.
>>> 
>>>> src/share/vm/jvmci/jvmciCompilerToVM.cpp
>>>> 
>>>> Why do we have to do the prev_##var##_sid == sid dance?  I guess it’s some optimization but does it really matter?
>>> It cuts down the number Strings allocated by about 35% (900 vs 582). With full string interning, the savings is around 55% (415) but the overhead of using a HashSet from VM code is prohibitive. I won’t argue strongly that it makes a big difference but since the one-element cache (per VMIntrinsicMethod string field) is fast and cheap, I don’t see why not to use it. The alternative code would look something like this:
>>> 
>>>  objArrayHandle vmIntrinsics = oopFactory::new_objArray(VMIntrinsicMethod::klass(), (vmIntrinsics::ID_LIMIT - 1), CHECK_NULL);
>>>  int index = 0;
>>> #define VM_SYMBOL_TO_STRING(s) java_lang_String::create_from_symbol(vmSymbols::symbol_at(vmSymbols::VM_SYMBOL_ENUM_NAME(s)), THREAD)
>>> #define VM_INTRINSIC_INFO(id, kls, name, sig, ignore_fcode) {                  \
>>>    instanceHandle vmIntrinsicMethod = InstanceKlass::cast(VMIntrinsicMethod::klass())->allocate_instance_handle(CHECK_NULL); \
>>>    Handle kls_string = VM_SYMBOL_TO_STRING(kls);                              \
>>>    Handle name_string = VM_SYMBOL_TO_STRING(name);                            \
>>>    Handle sig_string = VM_SYMBOL_TO_STRING(sig);                              \
>>>    VMIntrinsicMethod::set_declaringClass(vmIntrinsicMethod, kls_string());    \
>>>    VMIntrinsicMethod::set_name(vmIntrinsicMethod, name_string());             \
>>>    VMIntrinsicMethod::set_descriptor(vmIntrinsicMethod, sig_string());        \
>>>    VMIntrinsicMethod::set_id(vmIntrinsicMethod, vmIntrinsics::id);            \
>>>    vmIntrinsics->obj_at_put(index++, vmIntrinsicMethod());                    \
>>>  }
>>> 
>>>  VM_INTRINSICS_DO(VM_INTRINSIC_INFO, VM_SYMBOL_IGNORE, 
>>> VM_SYMBOL_IGNORE, VM_SYMBOL_IGNORE, VM_ALIAS_IGNORE) #undef 
>>> VM_SYMBOL_TO_STRING #undef VM_INTRINSIC_INFO
>>> 
>>> Better?
>>> 
>>> -Doug
>>> 
>>>> If we don’t have to do that I would prefer is that macro would be a method (or two).
>>>> 
>>>>> On Aug 18, 2016, at 6:50 AM, Doug Simon <doug.simon at oracle.com> wrote:
>>>>> 
>>>>> Please review this change which allows JVMCI compilers to see what intrinsics are defined by the VM and which methods have been annotated by HotSpotIntrisicCandidate.
>>>>> 
>>>>> https://bugs.openjdk.java.net/browse/JDK-8164358
>>>>> http://cr.openjdk.java.net/~dnsimon/8164358/
>>>>> 
>>>>> Thanks,
>>>>> 
>>>>> -Doug
> 
>