[llvm-commits] [PATCH] Reduce number of stubs used in 64bit code

[Evan Phoenix]

Anyone have a comment on this? If not, it would be great to make it  
into 2.6 if possible.

Thanks!

  - Evan

On Sep 1, 2009, at 2:34 PM, Evan Phoenix wrote:

> Currently the JIT running on a x86_64 platform can only call an  
> external function through a stub. This is because of a conservative  
> decision about how the encoding of a pc-relative address would  
> should up in the machine code stream. These stubs incur a penalty,  
> so any stubs that can be eliminated should be.
>
> The attached patch allows the JITEmitter to override the CodeGen's  
> decision to use a stub by validating if a stub is actually needed.  
> Thus any calling functions who's pc-relative offset fits directly in  
> a call instruction are used the same as they would on a 32bit  
> platform.
>
> "Long" calls are still done via the stub mechanism.
>
> This only effects the calling of externally defined functions. It  
> changes nothing with regard to lazy/future JIT'd LLVM functions.
>
> Thanks,
>
> - Evan Phoenix
>
>
> <llvm-64bit- 
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