RFR(S): 8056950: Compiled code (64-bit) on SPARC should sign extend INT parameters passed on registers to runtime or native methods.

[Tobias Hartmann]

Hi Goetz,

On 05.07.2016 12:09, Lindenmaier, Goetz wrote:
> Hi Tobias,
> 
> thanks for your comments!
> 
> For the widening issue -- it's not straight forward to implement.
> Each intrinsic has it's own section generating the type and call node.
> If these are fixed, it tends to be forgotten if new ones are added.
> 
> A generic approach would add the widening further down when
> generating the call, but there e.g. the type can not be changed any
> more because types are constant and it's passed down by reference.

Right, I agree that this is not easy to fix, so let's leave this for now.

Best regards,
Tobias

> 
> Best regards,
>   Goetz.
> 
>> -----Original Message-----
>> From: Tobias Hartmann [mailto:tobias.hartmann at oracle.com]
>> Sent: Dienstag, 5. Juli 2016 09:16
>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-compiler-
>> dev at openjdk.java.net
>> Subject: Re: RFR(S): 8056950: Compiled code (64-bit) on SPARC should sign
>> extend INT parameters passed on registers to runtime or native methods.
>>
>> Hi Goetz,
>>
>> thanks for taking care of this bug!
>>
>> I agree that we should think about fixing the C stubs by widening ints to longs
>> in C2 but as this is currently not an issue, I'm fine with your fix.
>>
>> Best regards,
>> Tobias
>>
>> On 04.07.2016 16:35, Lindenmaier, Goetz wrote:
>>> Hi,
>>>
>>>
>>>
>>> I had a look at "8056950: Compiled code (64-bit) on SPARC should sign
>> extend INT parameters passed on registers to runtime or native methods."
>> https://bugs.openjdk.java.net/browse/JDK-8056950  We fixed the same
>> issue for ppc.
>>>
>>>
>>>
>>> There are three parts to this:
>>>
>>>
>>>
>>> 1.) generate_native_wrapper(). The native wrapper should do the sign
>> extensions for the smaller ints.
>>>
>>> This was missing when 8056950 was opened, but fixed by "8148353: [linux-
>> sparc] Crash in libawt.so on Linux SPARC"
>>>
>>> in the meantime.
>> http://hg.openjdk.java.net/jdk9/hs/hotspot/rev/1f4f4866aee0
>>>
>>>
>>>
>>> 2.)  Stubs called directly like updateBytesCRC32C. If the C2 compiler passes
>> an int to these it is not
>>>
>>> correctly sign extended. updateBytesCRC32C and most others are
>> implemented in assembly, so one can
>>>
>>>  assure proper 32-bit instructions are used.
>>>
>>> A problem are stubs implemented in C, as montgomery_square() on ppc.
>> On ppc we solved this with
>>>
>>>  a trick in the platform implementations, see sharedRuntime_ppc.cpp:3445,
>> "len = len & 0x7fffFFFF;"
>>>
>>> Montgomery is not implemented on sparc, though. I did not find any other
>> similar on sparc.
>>>
>>>
>>>
>>> 3.) The optoStubs generated by the C2 compiler. The C2 compiler will insert
>> proper casts here if
>>>
>>>   CCallingConventionRequiresIntsAsLongs is set. So this needs to be set on
>> sparc.
>>>
>>>
>>>
>>> I propose the folowing simple, straight forward webrev:
>>>
>>> http://cr.openjdk.java.net/~goetz/wr16/8056950-
>> SparcIntToLong/webrev.01/
>>>
>>>
>>>
>>> For 2.)/montgtomery, one could think about implementing widening the
>> type of 'len' to
>>>
>>> long in C2, but it's currently not an issue.
>>>
>>>
>>>
>>> Best regards,
>>>
>>>   Goetz.
>>>