llvm dev - Aug 2006 - [LLVMdev] Re: JIT and garbage collection

On Sun, 6 Aug 2006, Reid Spencer wrote:
> Yes, the JIT implementation was recently improved to add support for
> this. There's nothing you need to do (or emit). The JIT implementation
> will automatically collect memory that is not being used. See the
> JITMemoryManager in lib/ExecutionEngine/JIT/JITEmitter.cpp for details.
The JIT doesn't automatically do this.  I don't track where function 
pointers are and autoreclaim.  The client must specifically request that 
specific functions code be deallocated.

-Chris
> On Sun, 2006-08-06 at 14:30 -0400, Hendrik Boom wrote:
>> If I recall correctly, the garbage collector interface consists mostly
of
>> some fuctions that one calls during execution to notify the collector
>> about a GC root. There's one othr thing that's needed if you do
JIT
>> compilation: you have to garbage-collect the generated code.  This
means
>> that the collector must be able to find where the pointers are in the
>> generated code together with metadata.
>>
>> Is there any support for this?
>>
>>
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-Chris

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http://llvm.org/

On Sun, 06 Aug 2006 12:04:31 -0700, Chris Lattner wrote:
> On Sun, 6 Aug 2006, Reid Spencer wrote:
>> Yes, the JIT implementation was recently improved to add support for
>> this. There's nothing you need to do (or emit). The JIT
implementation
>> will automatically collect memory that is not being used. See the
>> JITMemoryManager in lib/ExecutionEngine/JIT/JITEmitter.cpp for details.
> 
> The JIT doesn't automatically do this.  I don't track where
function
> pointers are and autoreclaim.  The client must specifically request that 
> specific functions code be deallocated.
Would it be a huge change for it to do this?  Besides issues of whether
the garbage collector itself contains garbage-collected code, of course.

-- hendrik

On Sun, 6 Aug 2006, Hendrik Boom wrote:
>> The JIT doesn't automatically do this.  I don't track where
function
>> pointers are and autoreclaim.  The client must specifically request
that
>> specific functions code be deallocated.
>
> Would it be a huge change for it to do this?  Besides issues of whether
> the garbage collector itself contains garbage-collected code, of course.
How would it work?  How would the JIT know where you put function 
pointers?

-Chris

-- 
http://nondot.org/sabre/
http://llvm.org/