> I don't think we want to do that. A REG_EQUAL/REG_EQUIV note can use a
> pseudo that isn't live and still be valid. Consider a simple example
> like this:
>
> a = b + 3
> // b dies here
> c = a {REG_EQUAL b+3}
>
> The REG_EQUAL note is valid and may help optimization. Removing it
> just because b is dead at that point would be unnecessarily
> pessimistic.
But if you have a REG_DEAD note for b on the first insn, then you cannot
rematerialize the REG_EQUAL note after it, otherwise bad things can happen.
See PR rtl-optimization/51505 for an example.
--
Eric Botcazou
