[llvm] [InstCombine] Use the select condition to try to constant fold binops into select (PR #84696)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

```
define i32 @before(i1 %cond) {
  %sel = select i1 %cond, i32 32, i32 0
  call void @use(i32 %sel)
  %ret = or disjoint i32 %sel, 16
  ret i32 %ret
}

define i32 @after(i1 %cond) {
  %sel = select i1 %cond, i32 32, i32 0
  call void @use(i32 %sel)
  %ret = select i1 %cond, i32 48, i32 16
  ret i32 %ret
}
```

I don't think the latter form is better than the former. Do we need the one-use check?


https://github.com/llvm/llvm-project/pull/84696