RFR: 8000489: older builds of hsdis don't work anymore after 6879063

[Krystal Mo]

Hi Yumin,

I just built hsdis with the new patch and dropped it into JDK7u5, and 
it's still missing newlines. Anyway, it not that bad, at least the 
disassembly contents are correct.

PrintInterpreter log on JDK7u5 ends with:

   Old hsdis:
       0x00007f8ae0e058d9: jmpq   *(%r10,%rbx,8)
       0x00007f8ae0e058dd: data32 xchg %ax,%ax
----------------------------------------------------------------------

   New hsdis:
       0x00007f26150208d9: jmpq   *(%r10,%rbx,8)
       0x00007f26150208dd: data32 xchg 
%ax,%ax----------------------------------------------------------------------

That's the only place that bothers me (a bit, but not that much).

Besides that I'm okay with this patch.

And I'm fine with the fact that SA couldn't use old hsdis to do disassembly.

Thanks for fixing this!
Kris

On 11/02/2012 02:06 AM, yumin.qi at oracle.com wrote:
> Hi, John and all
>
>   Please have a look for new webrev
> http://cr.openjdk.java.net/~minqi/8000489
>
>   The new code works fine:  new vm with new hsdis and old hsdis, old 
> vm with new hsdis and old hsdis.
>
>   (Kris, I tested both with -XX:+PrintInterpreter  and 
> -XX:+PrintAssembly separately, the output is OK, please let me know if 
> you find new problem with output format)
>
>   One problem is that SA could not work with old hsdis, the reason is 
> when decode an address, old hsdis read byte from the address. In fact, 
> when SA attached to process or core file, the address is from target 
> process or core file, not an address in SA process itself. When hsdis 
> read memory from this address --- it reads from SA process itself, 
> could not reach out to target space, so the output is wrong. With new 
> hsdis, we copy the bytes from target and pass into hsdis as a buffer, 
> and hsdis read byte from this buffer, but the address value itself is 
> only for print out. With old version hsdis, it will read from SA process.
>
> For VM disassemble output, using old version hsdis has no problem, 
> since the address hsdis read is from the process itself as expected.
>
>  I will file a bug to log this problem but no fix for it since the 
> interface has no more param for this.
>
> Thanks
> Yumin
>
>
>
>
> On 10/29/2012 10:47 AM, John Rose wrote:
>> On Oct 29, 2012, at 10:35 AM, Yumin Qi wrote:
>>
>>>   I haven't considered new JVM work with old hsdis. Will change 
>>> disassemble.cpp to check:
>>
>> Perfect!  Thanks, — John

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