Yes, it looks like the similar conditions are triggered by the code shown in that issue, but perhaps the reason isn't that indvars simplification pass couldn't really deduce the the value from last but one iteration (as seen in the example I shared: https://godbolt.org/z/5xhY1EcGb), but maybe the code structure introduced by this change?

We see that for a single-threaded system or with option '-mllvm -licm-force-thread-model-single', the generated code quality worsens for a very simple example: https://godbolt.org/z/5xhY1EcGb.

Sorry, but I can only add a bit more confusion: https://godbolt.org/z/fT19KTh34
There are two cases, only differing in terms of user-defined constructor.

@dblaikie
The condition FieldClass->isPOD() returns false for the following case (when considering field 'struct foo t' of 'struct foo1') :

Apologies for wrong patch (repeat of previous). I have now put up the latest patch. Please review and accept.

Restructured the code as suggested by @jeroen.dobbelaere

Added the missing computation of Known bits for the case Instruction::AShr. This should result in no change of functionality except when intended.

Modified the comment as suggested by @lebedev.ri

I have adapted the code as per @spatel's suggestion. This also solves the comments given on earlier version by @RKSimon.