[patch] shark llvm 2.6 JIT improved optimization level

[Andrew Haley]

Xerxes Rånby wrote:
> Andrew Haley skrev:
>> Xerxes Rånby wrote:
>>  
>>> The LLVM 2.6 JIT api have changed in order to give developers more
>>> fine-grained control of the optimization level of the JIT.
>>> http://lists.cs.uiuc.edu/pipermail/llvmdev/2009-April/021990.html
>>>
>>> The attached patch enables Shark to compile against the current llvm 2.6
>>> svn trunk.
>>> ... and makes the shark a bit more aggressive.
>>>
>>> Suggestions are welcome.
>>>     
>>
>> OK, I'll bite.  :-)
>>
>> This option should be accessible from the command line.

> I have committed the patch with a change to make it use the same
> optimization level as before since shark currently only have one
> optimization level.
> 
> If we want to be able to use the command line to set the optimization
> level then it could be implemented in a number of ways:
> 
> We could add a new -XX option like -XX:SharkOptimization=Aggressive
> 
> We could as well make shark hotspot respond to the "standard" -client
> and -server options in order to set the optimization suitable for
> responsive user interaction or  bulk server throughput.

I don't think that -client and -server really give us what we need.  In
order to find out what optimization levels we should use we need to be
able to benchmark with varying levels.  If there is a Java parameter that
corresponds with the LLVM levels, than we can use that, but I don't think
there is.

It might be, for example, that Aggressive optimization is pointless.  I
don't know.

Andrew.