Assembly output from JRuby 'fib'

[Rémi Forax]

It's astonishing how many people want to generate dead code :)

Rémi

On 04/30/2011 01:03 AM, Charles Nutter wrote:
> Rémi and I confirmed that it is in fact dead code (JRuby's fault) 
> which is causing a problem for ASM 4 (ASM's fault). He's looking into 
> a fix, and I'll try to eliminate the dead code.
>
> Hopefully it can be fixed in ASM soon, since the code in question is 
> being generated by a particularly gnarly part of JRuby's compiler.
>
> - Charlie (mobile)
>
> On Apr 29, 2011, at 15:58, Mark Roos <mroos at roos.com 
> <mailto:mroos at roos.com>> wrote:
>
>>
>> I have seen a stack map issue with ASM 4 as well.  In my case it was 
>> dead ( unreachable ) code which had
>> a return instruction in it.  Seemed to confuse the next stack map 
>> computation.  I am allowing ASM 4 to compute
>> the maps on its own.
>>
>> I replaced it (the return) with no ops and the problem went away. 
>>  The other dead instructions did not seem to
>> matter.
>>
>> mark
>>
>>
>> From: 	Charles Oliver Nutter <headius at headius.com 
>> <mailto:headius at headius.com>>
>> To: 	Da Vinci Machine Project <mlvm-dev at openjdk.java.net 
>> <mailto:mlvm-dev at openjdk.java.net>>
>> Date: 	04/28/2011 11:17 AM
>> Subject: 	Re: Assembly output from JRuby 'fib'
>> Sent by: 	mlvm-dev-bounces at openjdk.java.net 
>> <mailto:mlvm-dev-bounces at openjdk.java.net>
>>
>>
>> ------------------------------------------------------------------------
>>
>>
>>
>> On Thu, Apr 28, 2011 at 11:03 AM, Rémi Forax <forax at univ-mlv.fr 
>> <mailto:forax at univ-mlv.fr>> wrote:
>> > On 04/28/2011 03:56 PM, Charles Oliver Nutter wrote:
>> >> stack map is invalid. Could be an ASM bug?
>> >
>> > yes. it could :)
>> >
>> > Also it could be a bug on your side because to calculate stackmap
>> > ASM needs to be able to find the common supertype of two types.
>> > I don't know if you provide your own method for doing that but
>> > by default it relies on reflection (getSupperClass/isAssignableFrom)
>> > which doesn't work if your code use a Class that doesn't exist yet.
>>
>> If you're willing, I'll toss you 1.5 and 1.6 ASM-produced bytecode
>> off-list and perhaps you can help me figure out if I'm doing something
>> wrong or if ASM is choking on our peculiar code structure. I need this
>> working to start running tests with invokedynamic.
>>
>> - Charlie
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