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Auto merge of #45007 - undecidabot:optimize-iter, r=bluss

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Optimize comparison functions of Iterator

Replaced matching on tuples which led to less performant code generation. Testing on microbenchmarks consistently showed ~1.35x improvement in performance on my machine.

Fixes #44729.
This commit is contained in:
bors 2017-10-12 17:34:21 +00:00
commit dcbbfb6e80
1 changed files with 114 additions and 72 deletions
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186
src/libcore/iter/iterator.rs
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@ -2059,14 +2059,23 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return Ordering::Equal,
(None, _ ) => return Ordering::Less,
(_ , None) => return Ordering::Greater,
(Some(x), Some(y)) => match x.cmp(&y) {
Ordering::Equal => (),
non_eq => return non_eq,
let x = match self.next() {
None => if other.next().is_none() {
return Ordering::Equal
} else {
return Ordering::Less
},
Some(val) => val,
};
let y = match other.next() {
None => return Ordering::Greater,
Some(val) => val,
};
match x.cmp(&y) {
Ordering::Equal => (),
non_eq => return non_eq,
}
}
}
@ -2082,14 +2091,23 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return Some(Ordering::Equal),
(None, _ ) => return Some(Ordering::Less),
(_ , None) => return Some(Ordering::Greater),
(Some(x), Some(y)) => match x.partial_cmp(&y) {
Some(Ordering::Equal) => (),
non_eq => return non_eq,
let x = match self.next() {
None => if other.next().is_none() {
return Some(Ordering::Equal)
} else {
return Some(Ordering::Less)
},
Some(val) => val,
};
let y = match other.next() {
None => return Some(Ordering::Greater),
Some(val) => val,
};
match x.partial_cmp(&y) {
Some(Ordering::Equal) => (),
non_eq => return non_eq,
}
}
}
@ -2105,11 +2123,17 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return true,
(None, _) | (_, None) => return false,
(Some(x), Some(y)) => if x != y { return false },
}
let x = match self.next() {
None => return other.next().is_none(),
Some(val) => val,
};
let y = match other.next() {
None => return false,
Some(val) => val,
};
if x != y { return false }
}
}
@ -2124,11 +2148,17 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return false,
(None, _) | (_, None) => return true,
(Some(x), Some(y)) => if x.ne(&y) { return true },
}
let x = match self.next() {
None => return other.next().is_some(),
Some(val) => val,
};
let y = match other.next() {
None => return true,
Some(val) => val,
};
if x != y { return true }
}
}
@ -2143,18 +2173,21 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return false,
(None, _ ) => return true,
(_ , None) => return false,
(Some(x), Some(y)) => {
match x.partial_cmp(&y) {
Some(Ordering::Less) => return true,
Some(Ordering::Equal) => {}
Some(Ordering::Greater) => return false,
None => return false,
}
},
let x = match self.next() {
None => return other.next().is_some(),
Some(val) => val,
};
let y = match other.next() {
None => return false,
Some(val) => val,
};
match x.partial_cmp(&y) {
Some(Ordering::Less) => return true,
Some(Ordering::Equal) => (),
Some(Ordering::Greater) => return false,
None => return false,
}
}
}
@ -2170,18 +2203,21 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return true,
(None, _ ) => return true,
(_ , None) => return false,
(Some(x), Some(y)) => {
match x.partial_cmp(&y) {
Some(Ordering::Less) => return true,
Some(Ordering::Equal) => {}
Some(Ordering::Greater) => return false,
None => return false,
}
},
let x = match self.next() {
None => { other.next(); return true; },
Some(val) => val,
};
let y = match other.next() {
None => return false,
Some(val) => val,
};
match x.partial_cmp(&y) {
Some(Ordering::Less) => return true,
Some(Ordering::Equal) => (),
Some(Ordering::Greater) => return false,
None => return false,
}
}
}
@ -2197,18 +2233,21 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return false,
(None, _ ) => return false,
(_ , None) => return true,
(Some(x), Some(y)) => {
match x.partial_cmp(&y) {
Some(Ordering::Less) => return false,
Some(Ordering::Equal) => {}
Some(Ordering::Greater) => return true,
None => return false,
}
}
let x = match self.next() {
None => { other.next(); return false; },
Some(val) => val,
};
let y = match other.next() {
None => return true,
Some(val) => val,
};
match x.partial_cmp(&y) {
Some(Ordering::Less) => return false,
Some(Ordering::Equal) => (),
Some(Ordering::Greater) => return true,
None => return false,
}
}
}
@ -2224,18 +2263,21 @@ pub trait Iterator {
let mut other = other.into_iter();
loop {
match (self.next(), other.next()) {
(None, None) => return true,
(None, _ ) => return false,
(_ , None) => return true,
(Some(x), Some(y)) => {
match x.partial_cmp(&y) {
Some(Ordering::Less) => return false,
Some(Ordering::Equal) => {}
Some(Ordering::Greater) => return true,
None => return false,
}
},
let x = match self.next() {
None => return other.next().is_none(),
Some(val) => val,
};
let y = match other.next() {
None => return true,
Some(val) => val,
};
match x.partial_cmp(&y) {
Some(Ordering::Less) => return false,
Some(Ordering::Equal) => (),
Some(Ordering::Greater) => return true,
None => return false,
}
}
}