RFR(M): 8016697: PPC64 (part 5): Use stubs to implement safefetch

Vladimir Kozlov vladimir.kozlov at oracle.com
Tue Jul 2 15:17:03 PDT 2013 

Thank you, Goetz

We are doing review of closed changes. When they are ready I will push.

Thanks,
Vladimir

On 7/2/13 2:47 AM, Lindenmaier, Goetz wrote:
> Hi,
>
> Sorry for that, I didn't grok the comment.  The alignment is a good idea.
> Fixed:
> http://cr.openjdk.java.net/~goetz/webrevs/8016697-all/
>
> Best regards,
>    Goetz.
>
>
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com]
> Sent: Dienstag, 2. Juli 2013 01:17
> To: Lindenmaier, Goetz
> Cc: 'Christian Thalinger'; 'Albert Noll (albert.noll at oracle.com)'; 'ppc-aix-port-dev at openjdk.java.net'; 'hotspot-dev at openjdk.java.net'
> Subject: Re: RFR(M): 8016697: PPC64 (part 5): Use stubs to implement safefetch
>
> Goetz,
>
> Why you did not add 'nop' between load and return instructions on sparc?
> It was in assembler in .s file. The next comment said we need it:
>
>     !! By convention with the trap handler we ensure there is a non-CTI
>     !! instruction in the trap shadow.
>
> Also should we align code in stubs to keep it in one cache line?
>
>        __ align(CodeEntryAlignment);
>        *entry = __ pc();
>
> Thanks,
> Vladimir
>
> On 6/24/13 12:31 PM, Lindenmaier, Goetz wrote:
>> Hi,
>>
>> you are right, the check is redundant.
>> I removed it and updated the webrev and also based it on the
>> recent staging repo:
>> http://cr.openjdk.java.net/~goetz/webrevs/8016697-all/
>>
>> Best regards,
>>     Goetz.
>>
>>
>> -----Original Message-----
>> From: Christian Thalinger [mailto:christian.thalinger at oracle.com]
>> Sent: Monday, June 24, 2013 7:48 PM
>> To: Lindenmaier, Goetz
>> Cc: 'Vladimir Kozlov'; 'ppc-aix-port-dev at openjdk.java.net'; 'hotspot-dev at openjdk.java.net'
>> Subject: Re: RFR(M): 8016697: PPC64 (part 5): Use stubs to implement safefetch
>>
>>
>> On Jun 20, 2013, at 7:01 AM, "Lindenmaier, Goetz" <goetz.lindenmaier at sap.com> wrote:
>>
>>> Hi,
>>>
>>> I implemented the safefetch stubs for x86 and sparc (was quiet simple).
>>> This way I could clean up the #define right away.
>>>
>>> I tested it thouroughly on
>>>    x86_64: bsd, nt, linux, solaris
>>>    x86_32: nt, linux
>>> by adding it into our internal VM.
>>> Tonight I will get build/test on
>>>    sparc_64 solaris
>>>    sparc_32 solaris
>>>    x86_64 nt, linux
>>> with the openjdk ppc port, but I tested that before submitting in a smaller
>>> extend, too.
>>>
>>> Here the webrev:
>>> http://cr.openjdk.java.net/~goetz/webrevs/8016697-all/
>>
>> I like this change.  It removes a lot of duplication.  One comment:
>>
>> +  static bool is_safefetch_fault(address pc) {
>> +    return pc != NULL &&
>> +          (pc == _safefetch32_fault_pc ||
>> +           pc == _safefetchN_fault_pc);
>> +  }
>>
>> checks for pc != null.  Should we remove the check here?
>>
>> +  if (pc && StubRoutines::is_safefetch_fault(pc)) {
>> +    set_cont_address(uc, address(StubRoutines::continuation_for_safefetch_fault(pc)));
>>        return true;
>>      }
>>
>> -- Chris
>>
>>>
>>> Best regards,
>>>    Goetz.
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Christian Thalinger [mailto:christian.thalinger at oracle.com]
>>> Sent: Dienstag, 18. Juni 2013 22:44
>>> To: Lindenmaier, Goetz
>>> Cc: 'Vladimir Kozlov'; 'ppc-aix-port-dev at openjdk.java.net'; 'hotspot-dev at openjdk.java.net'
>>> Subject: Re: RFR(M): 8016697: PPC64 (part 5): Use stubs to implement safefetch
>>>
>>>
>>> On Jun 18, 2013, at 1:18 PM, "Lindenmaier, Goetz" <goetz.lindenmaier at sap.com> wrote:
>>>
>>>> Ok, I will implement it on x86.
>>>>
>>>> To get a single change, you can give me the sparc patch,
>>>> or you extend the webrev once I updated it with the
>>>> x86 code.
>>>
>>> Sounds good.  Let me know when it's there.
>>>
>>> -- Chris
>>>
>>>> If you prefer, you can also push it to some other repository, it
>>>> will end up in the ppc repo in time I guess.
>>>>
>>>> Best regards,
>>>> Goetz.
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Christian Thalinger [mailto:christian.thalinger at oracle.com]
>>>> Sent: Tuesday, June 18, 2013 6:59 PM
>>>> To: Lindenmaier, Goetz
>>>> Cc: Volker Simonis; Vladimir Kozlov; ppc-aix-port-dev at openjdk.java.net; hotspot-dev at openjdk.java.net
>>>> Subject: Re: RFR(M): 8016697: PPC64 (part 5): Use stubs to implement safefetch
>>>>
>>>>
>>>> On Jun 18, 2013, at 1:50 AM, "Lindenmaier, Goetz" <goetz.lindenmaier at sap.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> We have it on these platforms:
>>>>> ia64    (nt, linux, hp_ux)
>>>>> parisc (hp_ux)
>>>>> zArch (linux)
>>>>> ppc     (aix, linux)
>>>>>
>>>>> I would implement it on x86 & friends, you do it on sparc and wherever
>>>>> else you like it?
>>>>
>>>> That sounds reasonable.  Are we pushing this to the ppc repository then?
>>>>
>>>> -- Chris
>>>>
>>>>>
>>>>> Best regards,
>>>>> Goetz.
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Christian Thalinger [mailto:christian.thalinger at oracle.com]
>>>>> Sent: Dienstag, 18. Juni 2013 07:13
>>>>> To: Volker Simonis
>>>>> Cc: Lindenmaier, Goetz; Vladimir Kozlov; ppc-aix-port-dev at openjdk.java.net; hotspot-dev at openjdk.java.net
>>>>> Subject: Re: RFR(M): 8016697: PPC64 (part 5): Use stubs to implement safefetch
>>>>>
>>>>>
>>>>> On Jun 17, 2013, at 10:08 AM, Volker Simonis <volker.simonis at gmail.com> wrote:
>>>>>
>>>>>> Hi Goetz,
>>>>>>
>>>>>> I think the change is good and if the other reviewers don't decide to
>>>>>> implement it for the current platforms we can push it.
>>>>>
>>>>> I talked with Vladimir about this today and I my opinion we should use this stub on all platforms.  On which other platforms are you guys having this?
>>>>>
>>>>> -- Chris
>>>>>
>>>>>>
>>>>>> By the way, the makefile changes in ppc64.make will follow in patch 8 for
>>>>>> linux [1] and patch 14 for aix [2].
>>>>>> The implementation of the stubs will be in patch 9 for linux [3] and patch
>>>>>> 15 for aix [4] (only the signal handling part).
>>>>>>
>>>>>> Regards,
>>>>>> Volker
>>>>>>
>>>>>> [1]
>>>>>> http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/tip/ppc_patches/0008_linux_ppc_make_changes.patch
>>>>>> [2]
>>>>>> http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/tip/ppc_patches/0014_aix_make_changes.patch
>>>>>> [3]
>>>>>> http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/tip/ppc_patches/0009_linux_ppc_files.patch
>>>>>> [4]
>>>>>> http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/tip/ppc_patches/0015_aix_ppc_files.patch
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Jun 17, 2013 at 3:55 PM, Lindenmaier, Goetz <
>>>>>> goetz.lindenmaier at sap.com> wrote:
>>>>>>
>>>>>>> Hi,****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> the PPC64 port uses stub routines to implement safefetch. We had and****
>>>>>>>
>>>>>>> have problems with inline assembly, especially with non-gcc****
>>>>>>>
>>>>>>> compilers. Stub routines allow to implement safefetch without****
>>>>>>>
>>>>>>> depending on OS or compiler, as it's the case with the current****
>>>>>>>
>>>>>>> implementation. This also allows to use a single implementation if an****
>>>>>>>
>>>>>>> architecture is supported on several os platforms.****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> http://cr.openjdk.java.net/~goetz/webrevs/8016697-safefetch/****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> Currently, we guard the code with ****
>>>>>>>
>>>>>>> #ifdef SAFEFETCH_STUBS****
>>>>>>>
>>>>>>> which is set in ppc64.make.****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> I could also imagine an implementation that uses a pd_debug flag****
>>>>>>>
>>>>>>> or a const flag set in os_<os_cpu>.hpp that allows the C-compiler to ****
>>>>>>>
>>>>>>> optimize, and writing the code like this:****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> extern "C" int pd_SafeFetch32 (int * adr, int errValue) ;****
>>>>>>>
>>>>>>> extern "C" intptr_t pd_SafeFetchN (intptr_t * adr, intptr_t errValue) ;***
>>>>>>> *
>>>>>>>
>>>>>>> inline int SafeFetch32(int* adr, int errValue) {****
>>>>>>>
>>>>>>> if (UseSafefetchStub) {****
>>>>>>>
>>>>>>> assert(StubRoutines::SafeFetch32_stub(), "stub not yet generated");***
>>>>>>> *
>>>>>>>
>>>>>>> return StubRoutines::SafeFetch32_stub()(adr, errValue);****
>>>>>>>
>>>>>>> } else {****
>>>>>>>
>>>>>>> pd_SafeFetch32(adr, errValue);****
>>>>>>>
>>>>>>> }****
>>>>>>>
>>>>>>> }****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> Unfortunately this requires ****
>>>>>>>
>>>>>>> 1) setting the flag on all platforms****
>>>>>>>
>>>>>>> 2) renaming the safefetch function on all platfoms.****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> Actually I would prefer this second solution as it avoids the
>>>>>>> preprocessor, ****
>>>>>>>
>>>>>>> and am happy to edit the sources accordingly if this finds acceptance.****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> For the implementation of a safefetch_stub see****
>>>>>>>
>>>>>>>
>>>>>>> http://hg.openjdk.java.net/ppc-aix-port/jdk8/hotspot/file/fce884e5ba0b/src/cpu/ppc/vm/stubGenerator_ppc.cpp
>>>>>>> ****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> Could I get a review on this change, please?****
>>>>>>>
>>>>>>> ** **
>>>>>>>
>>>>>>> Thanks,****
>>>>>>>
>>>>>>> Goetz.****
>>>>>>>
>>>>>
>>>>
>>>
>>

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