Enum Reads 

pub enum Reads {
    Zero,
    Signed,
    Unsigned,
    Carry,
}

Which part of what a comparison against zero left a condition is about.

Variants

Zero

Whether the value was zero, and nothing else.

Signed

Where the value sits against zero as a signed number, which is the sign and the overflow.

Unsigned

Where it sits as an unsigned number, which is the carry, alone or with the zero.

Carry

The carry as the instruction in front left it, which no comparison is a substitute for.

The other three are parts of the answer to a question, so an instruction that has already asked that question can stand in for the one that would have asked it again. An add with carry is not reading an answer. It is reading the bit that fell off the end of the addition in front of it, and the only thing that leaves that bit is that addition, so nothing this pass could put there instead is the same. Zeroing::covers says no to it for every entry there is and will go on saying no to every entry added later, which is what keeps a comparison in front of one of these where the program put it.

Trait Implementations

impl Clone for Reads

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Reads

impl Debug for Reads

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Reads

impl PartialEq for Reads

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Reads