[LLVMdev] RFC: Profiling Enhancements (GSoC)

[Alastair Murray]

Hi Evan,

On 17/07/12 09:44, Evan Cheng wrote:
> In addition to your planned tasks, you might want to put in some work
> to ensure branch probabilities are not lost during optimization. One
> known issue is LLVM optimizer can turn branchy code into switch
> statements and it would completely discard probability.

Yes, I should of mentioned this in my email.  It was mentioned in the 
other thread that this was always part of my plan, but probably post-GSoC.

Preserving branch metadata, however, seems easier than preserving 
ProfileInfo, so I may be able to get started on this sooner.  I've only 
just started looking at how to this though.


> Here is a  simple example: <snip>

Thank you, I'll have a look at where the information becomes inaccurate 
for this example, and probably write quite a few more!

Regards,
Alastair.