LLVM: lib/Transforms/IPO/HotColdSplitting.cpp File Reference (original) (raw)

The goal of hot/cold splitting is to improve the memory locality of code. More...

The goal of hot/cold splitting is to improve the memory locality of code.

The splitting pass does this by identifying cold blocks and moving them into separate functions.

When the splitting pass finds a cold block (referred to as "the sink"), it grows a maximal cold region around that block. The maximal region contains all blocks (post-)dominated by the sink [*]. In theory, these blocks are as cold as the sink. Once a region is found, it's split out of the original function provided it's profitable to do so.

[*] In practice, there is some added complexity because some blocks are not safe to extract.

TODO: Use the PM to get domtrees, and preserve BFI/BPI. TODO: Reorder outlined functions.

Definition in file HotColdSplitting.cpp.