[llvm] [SCEV] Fold zext(C+A)<nsw> -> (sext(C) + zext(A))<nsw> if possible. (PR #142599)

[Florian Hahn via llvm-commits]

fhahn wrote:

> Compile-time impact is peculiar: https://llvm-compile-time-tracker.com/compare.php?from=100a1d0c4caad0d0f2ec26b07d3cc73f59b9a9a8&to=6d78ba4a9c028477904dd915f34a6ea8854b15a2&stat=instructions:u Not much on CTMark, but +0.4% on clang ThinLTO: https://llvm-compile-time-tracker.com/compare_clang.php?from=100a1d0c4caad0d0f2ec26b07d3cc73f59b9a9a8&to=6d78ba4a9c028477904dd915f34a6ea8854b15a2&stat=instructions%3Au&sortBy=interestingness

Ah interesting. Let me see if I can pin down where this is coming from.

https://github.com/llvm/llvm-project/pull/142599