From 3264c836bbbbf9d62bc088443ca844709f8746a1 Mon Sep 17 00:00:00 2001 From: Matt Date: Wed, 4 Oct 2017 00:55:57 +0800 Subject: [PATCH] Optimize comparison functions of Iterator Replaced matching on tuples which led to less performant code generation. --- src/libcore/iter/iterator.rs | 186 +++++++++++++++++++++-------------- 1 file changed, 114 insertions(+), 72 deletions(-) diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs index e9e31065cf876..79767b37601f8 100644 --- a/src/libcore/iter/iterator.rs +++ b/src/libcore/iter/iterator.rs @@ -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, } } }