What means "potential regression"?

this commit has comment that “This was shown as a potential regression in D126040.”.
what is means of this?

cc: @rotateright

This was explained here: ⚙ D126040 [InstCombine] Fold a mul with bool value into and

I read that discourse before question.
sorry, but still I could not follow you.

I’m working at this issue:

and it causes by

so, I wonder that this commit will removed or not.
If there is no reason for it to be removed, I will try to find another solution.

The previous commit to restrict the transform looks correct. If we do not check for extra uses, then the transform could create more IR instructions than we started with. We usually do not want to do that.

To restore the optimizations for patterns shown in your example code, you should probably match patterns starting from an “icmp eq 0” and create 1 or 2 logic instructions:

This could be generalized for zext/sext, different logic (and/or/xor) instructions, and eq/ne predicates.

@rotateright thank you! That’s what I want to know.
And thank you for your kind advice too.