[llvm] [InstCombine] Canonicalize xor with disjoint ops to or disjoint (PR #133139)

[Jeffrey Byrnes via llvm-commits]

jrbyrnes wrote:

For my purposes, what is most beneficial is:

```
%i48 = and i32 %i28, 1
%i.not2 = icmp eq i32 %i48, 0
%i49 = and i32 %i28, 2
%i50 = icmp eq i32 %i49, 0
%i144 = select i1 %i.not2, i32 0, i32 72
%i145 = select i1 %i50, i32 0, i32 144
%i146 = or disjoint i32 %i144, %i145
```

->

```
%temp = and i32 %i32, 3
%146 = mul %temp, 72
```

Which I imagine produces better code even for hardwares which prefer icmp->select over mul.

https://github.com/llvm/llvm-project/pull/133139