[LLVMdev] jit DLLs

Chris Lattner sabre at nondot.org
Tue Jun 24 22:30:17 PDT 2008

On Jun 24, 2008, at 12:46 PM, √ėyvind Harboe wrote:

>> ?yvind Harboe wrote:
>>> Are JIT DLLs supported?
>>> The idea is to use llvm to put performance sensitive code into
>>> a DLL that a Windows app can then use.
>>> This would build the performance sensitive code on the target
>>> machine making it possible to exploit CPU specific x86
>>> vector instructions.
>>> The code that calls fn's in the DLL should, ideally, be unaware
>>> that a llvm JIT is being used.
>> because of the size of the LLVM libraries, it would usually be  
>> preferable to pre-build versions of the performance
>> sensitive code for all target CPUs in separate dlls and use CPU  
>> identification code (similar to what the LLVM JIT does)
>> to resolve which dll to load at run time.
> Actually size doesn't matter. What's 10-20mByte amongst friends  
> these days? :-)
> What's the compressed size? (Decompressed *really* does not matter
> on a PC these days...)
> What matters is that the binaries can be shipped
> as part of the installation and live side by side by other  
> installations and
> that the solution is as complete as possible so as for me to be able
> to hit the ground running.

For the JIT and a couple of optimizers on x86 (suitably stripped etc),  
we see it taking ~2M uncompressed.  Additionally, as you say, this is  
very compressible for an install image.


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