Editing Register allocation (section)

==== Hybrid allocation ====
Some other register allocation approaches do not limit to one technique to optimize register's use. Cavazos et al., for instance, proposed a solution where it is possible to use both the linear scan and the graph coloring algorithms.{{sfn|Eisl|Marr|Würthinger|Mössenböck|2017|p=11}} In this approach, the choice between one or the other solution is determined dynamically: first, a [[machine learning]] algorithm is used "offline", that is to say not at runtime, to build a heuristic function that determines which allocation algorithm needs to be used. The heuristic function is then used at runtime; in light of the code behavior, the allocator can then choose between one of the two available algorithms.{{sfn|Cavazos|Moss|O’Boyle|2006|p=124-127}}

Trace register allocation is a recent approach developed by Eisl et al.{{sfn|Eisl|Grimmer|Simon|Würthinger|2016|p=14:1}}{{sfn|Eisl|Grimmer|Simon|Würthinger|2016|p=1}} This technique handles the allocation locally: it relies on dynamic [[Profiling (computer programming)|profiling]] data to determine which branches will be the most frequently used in a given control flow graph. It then infers a set of "traces" (i.e. code segments) in which the merge point is ignored in favor of the most used branch. Each trace is then independently processed by the allocator. This approach can be considered as hybrid because it is possible to use different register allocation algorithms between the different traces.{{sfn|Eisl|Grimmer|Simon|Würthinger|2016|p=4}}