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

[Florian Hahn via llvm-commits]

fhahn wrote:

Hmm, the impact in Clang seems down to the extra work constructing and reasoning about the newly created expression (or additional transforms), not due to the additional checks whether the transform is valid. Just doing the analysis w/o construting the new SCEV completely removes the compile-time impact for the clang build: http://llvm-compile-time-tracker.com/compare.php?from=e2639eefaabdfc06adad1a4458b6900d9838e64f&to=011614dacd9e201587843351dd54d1342ad0d622&stat=instructions:u


Not sure what the best next steps would be to get this wrapped up

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