Hot and Cold Partitioning (Was: GCC 4.1 Projects)

[Mark Mitchell]

Caroline Tice wrote:

> There might be some validity in the idea of modifying this optimization, 
> in the future, to consider
> the size of a basic block in addition to it's "hot-ness", when deciding 
> which partition to put it into.
> I expect this would not be that difficult to implement, and would 
> probably address your concerns.
> 
> However, at the moment, I would first like to get the "correctness" 
> fixes for the hot/cold partitioning
> optimization into FSF mainline. 

I agree.  The optimization is already checked in; as I understand it, 
all you are trying to do is make it work better on more systems, such as 
those with DWARF.  I think that Joern's objections can be dealt with 
after you get those fixes in place; I would imagine that you would just 
mark small basic blocks directly reachable from hot blocks as "hot", 
whether or not profiling data actually suggested them to be hot.

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Mark Mitchell
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