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

[Doug Simon]

> On 19 Aug 2016, at 23:18, Christian Thalinger <cthalinger at twitter.com> wrote:
> 
> 
>> On Aug 19, 2016, at 5:01 AM, Doug Simon <doug.simon at oracle.com> wrote:
>> 
>> I changed it to only try reuse the declaringClass string (which has the most overlap):
>> 
>> http://cr.openjdk.java.net/~dnsimon/8164358v2/
> 
> Looks good.  The only comment I have is about:
>    VMField::klass()->initialize(thread);
>    VMFlag::klass()->initialize(thread);
> 
> +  VMIntrinsicMethod::klass()->initialize(thread);
> We should use CHECK_NULL here too.  Sure, it's very unlikely these fail but better safe than sorry.

Thanks for catching this! I don’t think I’ll ever develop the eye you have for consistent exception propagation in VM code. I’ve spent too much time spent in a language where this is automatic ;-)

I’ve made the change in the v2 webrev.

-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
>>>> 
>>> 
>> 
>