Re: [PATCH] [Aarch64] Optimize subtract in shift counts

[Richard Kenner]

> That is simplify:
> (SHIFT A (32 - B)) -> (SHIFT A (AND (NEG B) 31))
> etc.

I think you need SHIFT_COUNT_TRUNCATED to be true for this to be
valid, but this is exactly what I was getting at in my last message.