[llvm] [ValueTracking] Handle `icmp pred (trunc X), C` in `computeKnownBitsFromCmp` (PR #82803)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> Hm, I wonder why this causes code size regressions, especially on mafft (https://llvm-compile-time-tracker.com/compare.php?from=0cbbcf1ef006ce13a1fa94960067723982ae955a&to=3589cacfa8da89b9b5051e4dba659caa575e6b3f&stat=size-text).

Reverting this patch cannot improve the code size.
https://github.com/dtcxzyw/llvm-ci/pull/1107#issuecomment-1983185593

https://github.com/llvm/llvm-project/pull/82803