[InstCombine] Fix miscompilation in `sinkNotIntoLogicalOp` (#142727)

Consider the following case:
```
define i1 @src(i8 %x) {
  %cmp = icmp slt i8 %x, -1
  %not1 = xor i1 %cmp, true
  %or = or i1 %cmp, %not1
  %not2 = xor i1 %or, true
  ret i1 %not2
}
```
`sinkNotIntoLogicalOp(%or)` calls `freelyInvert(%cmp,
/*IgnoredUser=*/%or)` first. However, as `%cmp` is also used by `Op1 =
%not1`, the RHS of `%or` is set to `%cmp.not = xor i1 %cmp, true`. Thus
`Op1` is out of date in the second call to `freelyInvert`. Similarly,
the second call may change `Op0`. According to the analysis above, I
decided to avoid this fold when one of the operands is also a user of
the other.

Closes https://github.com/llvm/llvm-project/issues/142518.

0 files changed, 0 insertions, 0 deletions