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

[Lindenmaier, Goetz]

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. 
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.****
>>> 
>