This is a patch that updates the cost of select i1 a, b, false to be equivalent to that of and i1 a, b
as well as the cost of select i1 a, true, b equivalent to or i1 a, b.
Until now, these selects were folded into and/or i1 by InstCombine, but the transformation is poison-unsafe.
This is a step towards removing the unsafe transformation. D93065 has relevant transformations linked.
These selects should be translated into the assemblies as and/or i1 do in the same manner. The cost should be equivalent.