Request for review: 8004076: Move _max_locals and _size_of_parameters to ConstMethod for better sharing

[Jiangli Zhou]

Thanks, John!

Jiangli

On 12/11/2012 08:00 PM, John Rose wrote:
> On Dec 11, 2012, at 5:38 PM, Jiangli Zhou wrote:
>
>> I see CompressedStream uses UNSIGNED5 coding of Pack200. I tried to 
>> google around for the UNSIGNED5 coding compression rate, but without 
>> much luck. If you have any info on that, please share. I was trying 
>> to find some usage examples in the VM code, but there seems no usage 
>> of CompressedStream (except the sa agent java code). Do you have any 
>> pointer?
>
> Right; you started with the comments here:
> http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/tip/src/share/vm/code/compressedStream.hpp
>
> Detailed definitions for UNSIGNED5 and related codings are in the 
> pack200 spec:
> http://docs.oracle.com/javase/6/docs/technotes/guides/pack200/pack-spec.html#tocInEnSc
>
> There is also a more focused description here in the Java source code:
> http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/tip/src/share/classes/com/sun/java/util/jar/pack/Coding.java
>
> Then we have BandStructure.java: 108: final static Coding UNSIGNED5 = 
> Coding.of(5,64);
>
> To search for compressed stream use in HotSpot, look for subtypes of 
> either the read or write version.
>   grep -n CompressedReadStream $(hg loc -I src)
>   grep -n CompressedWriteStream $(hg loc -I src)
>
> Then look at DebugInfoReadStream and CompressedLineNumberReadStream, 
> and the writer versions.  There's a lot of compressed metadata in the 
> code cache, and interpreter oop maps use it.  It is not used in 
> metadata, yet.
>
> — John

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