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,

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.
>