[llvm] [GlobalISel] Import samesign flag (second attempt) (PR #114267)

[Antonio Frighetto via llvm-commits]

antoniofrighetto wrote:

Drop second attempt from the title, it's not relevant. Please put some love in the commit description (no need to credit any PR, this is a relanding rather than reverting, maybe punctualize this has been extended to MI parsing, not just GISel). Please, exercize some due diligence verifying no similar effort has been carried out by somebody else (the MI changes had been already added in the other PR; at the very least, please add yourself in the ongoing tracking related issue).

https://github.com/llvm/llvm-project/pull/114267