[llvm] [CodeLayout] Size-aware machine block placement (PR #109711)

[via llvm-commits]

spupyrev wrote:

@nocchijiang we tried to modify the optimization so that it places cold blocks at the end of the layout. Unfortunately, there were no compressed/uncompressed size improvements over a set of large apps, including Swift-heavy ones. I did observe the behavior you describe (cold brk in the middle of the layout) but placing them at the end doesn't seem to be beneficial. (Theoretically, there might be some value of integrating block hotness into the placement, and i'd be happy to review diffs, if you find a good way of doing so)

https://github.com/llvm/llvm-project/pull/109711