[LLVMdev] Dynamic (JIT) type resolution

BGB cr88192 at hotmail.com
Tue Nov 6 13:21:21 PST 2007

----- Original Message ----- 
From: "Nicolas Geoffray" <nicolas.geoffray at lip6.fr>
To: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu>
Sent: Wednesday, November 07, 2007 6:17 AM
Subject: Re: [LLVMdev] Dynamic (JIT) type resolution

> Chris Lattner wrote:
>> I don't see how it's the same issue.  Once you jit it, it is just machine
>> code.  Updating the machine code with better code seems like a reasonable
>> and obvious optimization.
> That's what I want to do! ;-) However, from what I understand, your
> solution is to recompile the method. And I don't want to do that. I only
> want to dynamically patch the field operation in the native code.

maybe a tradeoff is possible:
the function to get the offset is replaced by a function pointer and a stub 
(avoiding many of the general problems involved with using 

the fist time it is called, the function pointer points to 'stub A', which 
calls the function to lookup the slot offset,
this function then stores the value in a variable, and updates the function 
pointer to point to 'stub B'.

'stub B', simply returns the value stored in the variable.

this should not be too difficult to implement I would think (albeit 
admittedly I still don't know a whole lot about LLVM).

hope this is of some use, in any case.

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