[PATCH] Speed up creation of live ranges for physical registers by using a segment set

[Quentin Colombet]

Hi all,

I agree with Vaidas that moving the set outside of the LiveRange may not be that easy.

Regarding the complexity improvements:

> for the createDeadDefs() part it may be interesting to simply append the new segments to the vector in any order and later run a sorting algorithm which also eliminates duplicates on the vector. This should reduce the O(n**2) complexity to O(n log n) and I'd imagine it to perform well in the case where only a few segments are used.


I am not so sure that would be beneficial, indeed, we would have to do this sorting for each live range, i.e., O(m n log n) and I suspect that the (log n) factor will be bigger than the cost of the set for the cases we try to optimize.

Thanks,
-Quentin


http://reviews.llvm.org/D6013

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