[InstCombine] Replace an integer comparison of a `phi` node with multiple `ucmp`/`scmp` operands and a constant with `phi` of individual comparisons of original intrinsic's arguments (#107769)
When we have a `phi` instruction with more than one of its incoming
values being a call to `ucmp` or `scmp`, which is then compared with an
integer constant, we can move the comparison through the `phi` into the
incoming basic blocks because we know that a comparison of `ucmp`/`scmp`
with a constant will be simplified by the next iteration of InstCombine.
There's a high chance that other similar patterns can be identified, in
which case they can be easily handled by the same code by moving the
check for "simplifiable" instructions into a lambda.
llvm-project
21e3a212 - [InstCombine] Replace an integer comparison of a `phi` node with multiple `ucmp`/`scmp` operands and a constant with `phi` of individual comparisons of original intrinsic's arguments (#107769)
