From cd002392ed4f8304f6af3655b1572e0fac3c2428 Mon Sep 17 00:00:00 2001
From: Jef <jackefransham@gmail.com>
Date: Fri, 18 May 2018 11:50:43 +0200
Subject: [PATCH] Add benchmarks for smallvec when it's on the stack

---
 benches/bench.rs | 315 ++++++++++++++++++++++++-----------------------
 lib.rs           |   2 +-
 2 files changed, 161 insertions(+), 156 deletions(-)

diff --git a/benches/bench.rs b/benches/bench.rs
index 7196176..9d5fc0b 100644
--- a/benches/bench.rs
+++ b/benches/bench.rs
@@ -4,216 +4,221 @@
 extern crate smallvec;
 extern crate test;
 
-use smallvec::SmallVec;
 use self::test::Bencher;
+use smallvec::{ExtendFromSlice, SmallVec};
 
-#[bench]
-fn bench_push(b: &mut Bencher) {
+const VEC_SIZE: usize = 16;
+
+trait Vector<T>: for<'a> From<&'a [T]> + Extend<T> + ExtendFromSlice<T> {
+    fn new() -> Self;
+    fn push(&mut self, val: T);
+    fn pop(&mut self) -> Option<T>;
+    fn insert(&mut self, n: usize, val: T);
+    fn from_elem(val: T, n: usize) -> Self;
+}
+
+impl<T: Copy> Vector<T> for Vec<T> {
+    fn new() -> Self {
+        Self::with_capacity(VEC_SIZE)
+    }
+    fn push(&mut self, val: T) {
+        self.push(val)
+    }
+    fn pop(&mut self) -> Option<T> {
+        self.pop()
+    }
+    fn insert(&mut self, n: usize, val: T) {
+        self.insert(n, val)
+    }
+    fn from_elem(val: T, n: usize) -> Self {
+        vec![val; n]
+    }
+}
+
+impl<T: Copy> Vector<T> for SmallVec<[T; VEC_SIZE]> {
+    fn new() -> Self {
+        Self::new()
+    }
+    fn push(&mut self, val: T) {
+        self.push(val)
+    }
+    fn pop(&mut self) -> Option<T> {
+        self.pop()
+    }
+    fn insert(&mut self, n: usize, val: T) {
+        self.insert(n, val)
+    }
+    fn from_elem(val: T, n: usize) -> Self {
+        smallvec![val; n]
+    }
+}
+
+macro_rules! make_benches {
+    ($typ:ty { $($b_name:ident => $g_name:ident($($args:expr),*),)* }) => {
+        $(
+            #[bench]
+            fn $b_name(b: &mut Bencher) {
+                $g_name::<$typ>($($args,)* b)
+            }
+        )*
+    }
+}
+
+make_benches! {
+    SmallVec<[u64; VEC_SIZE]> {
+        bench_push => gen_push(100),
+        bench_push_small => gen_push(VEC_SIZE as _),
+        bench_insert => gen_insert(100),
+        bench_insert_small => gen_insert(VEC_SIZE as _),
+        bench_extend => gen_extend(100),
+        bench_extend_small => gen_extend(VEC_SIZE as _),
+        bench_from_slice => gen_from_slice(100),
+        bench_from_slice_small => gen_from_slice(VEC_SIZE as _),
+        bench_extend_from_slice => gen_extend_from_slice(100),
+        bench_extend_from_slice_small => gen_extend_from_slice(VEC_SIZE as _),
+        bench_macro_from_elem => gen_from_elem(100),
+        bench_macro_from_elem_small => gen_from_elem(VEC_SIZE as _),
+        bench_pushpop => gen_pushpop(),
+    }
+}
+
+make_benches! {
+    Vec<u64> {
+        bench_push_vec => gen_push(100),
+        bench_push_vec_small => gen_push(VEC_SIZE as _),
+        bench_insert_vec => gen_insert(100),
+        bench_insert_vec_small => gen_insert(VEC_SIZE as _),
+        bench_extend_vec => gen_extend(100),
+        bench_extend_vec_small => gen_extend(VEC_SIZE as _),
+        bench_from_slice_vec => gen_from_slice(100),
+        bench_from_slice_vec_small => gen_from_slice(VEC_SIZE as _),
+        bench_extend_from_slice_vec => gen_extend_from_slice(100),
+        bench_extend_from_slice_vec_small => gen_extend_from_slice(VEC_SIZE as _),
+        bench_macro_from_elem_vec => gen_from_elem(100),
+        bench_macro_from_elem_vec_small => gen_from_elem(VEC_SIZE as _),
+        bench_pushpop_vec => gen_pushpop(),
+    }
+}
+
+fn gen_push<V: Vector<u64>>(n: u64, b: &mut Bencher) {
     #[inline(never)]
-    fn push_noinline(vec: &mut SmallVec<[u64; 16]>, x: u64) {
-        vec.push(x)
+    fn push_noinline<V: Vector<u64>>(vec: &mut V, x: u64) {
+        vec.push(x);
     }
 
     b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
-        for x in 0..100 {
+        let mut vec = V::new();
+        for x in 0..n {
             push_noinline(&mut vec, x);
         }
         vec
     });
 }
 
-#[bench]
-fn bench_insert(b: &mut Bencher) {
+fn gen_insert<V: Vector<u64>>(n: u64, b: &mut Bencher) {
     #[inline(never)]
-    fn insert_noinline(vec: &mut SmallVec<[u64; 16]>, x: u64) {
+    fn insert_noinline<V: Vector<u64>>(vec: &mut V, x: u64) {
         vec.insert(0, x)
     }
 
     b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
-        for x in 0..100 {
+        let mut vec = V::new();
+        for x in 0..n {
             insert_noinline(&mut vec, x);
         }
         vec
     });
 }
 
+fn gen_extend<V: Vector<u64>>(n: u64, b: &mut Bencher) {
+    b.iter(|| {
+        let mut vec = V::new();
+        vec.extend(0..n);
+        vec
+    });
+}
+
+fn gen_from_slice<V: Vector<u64>>(n: u64, b: &mut Bencher) {
+    let v: Vec<u64> = (0..n).collect();
+    b.iter(|| {
+        let vec = V::from(&v);
+        vec
+    });
+}
+
+fn gen_extend_from_slice<V: Vector<u64>>(n: u64, b: &mut Bencher) {
+    let v: Vec<u64> = (0..n).collect();
+    b.iter(|| {
+        let mut vec = V::new();
+        vec.extend_from_slice(&v);
+        vec
+    });
+}
+
+fn gen_pushpop<V: Vector<u64>>(b: &mut Bencher) {
+    #[inline(never)]
+    fn pushpop_noinline<V: Vector<u64>>(vec: &mut V, x: u64) {
+        vec.push(x);
+        vec.pop();
+    }
+
+    b.iter(|| {
+        let mut vec = V::new();
+        for x in 0..100 {
+            pushpop_noinline(&mut vec, x);
+        }
+        vec
+    });
+}
+
+fn gen_from_elem<V: Vector<u64>>(n: usize, b: &mut Bencher) {
+    b.iter(|| {
+        let vec = V::from_elem(42, n);
+        vec
+    });
+}
+
 #[bench]
 fn bench_insert_many(b: &mut Bencher) {
     #[inline(never)]
-    fn insert_many_noinline<I: IntoIterator<Item=u64>>(
-        vec: &mut SmallVec<[u64; 16]>, index: usize, iterable: I) {
+    fn insert_many_noinline<I: IntoIterator<Item = u64>>(
+        vec: &mut SmallVec<[u64; VEC_SIZE]>,
+        index: usize,
+        iterable: I,
+    ) {
         vec.insert_many(index, iterable)
     }
 
     b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
+        let mut vec = SmallVec::<[u64; VEC_SIZE]>::new();
         insert_many_noinline(&mut vec, 0, 0..100);
         insert_many_noinline(&mut vec, 0, 0..100);
         vec
     });
 }
 
-#[bench]
-fn bench_extend(b: &mut Bencher) {
-    b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
-        vec.extend(0..100);
-        vec
-    });
-}
-
-#[bench]
-fn bench_from_slice(b: &mut Bencher) {
-    let v: Vec<u64> = (0..100).collect();
-    b.iter(|| {
-        let vec: SmallVec<[u64; 16]> = SmallVec::from_slice(&v);
-        vec
-    });
-}
-
-#[bench]
-fn bench_extend_from_slice(b: &mut Bencher) {
-    let v: Vec<u64> = (0..100).collect();
-    b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
-        vec.extend_from_slice(&v);
-        vec
-    });
-}
-
 #[bench]
 fn bench_insert_from_slice(b: &mut Bencher) {
     let v: Vec<u64> = (0..100).collect();
     b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
+        let mut vec = SmallVec::<[u64; VEC_SIZE]>::new();
         vec.insert_from_slice(0, &v);
         vec.insert_from_slice(0, &v);
         vec
     });
 }
 
-#[bench]
-fn bench_pushpop(b: &mut Bencher) {
-    #[inline(never)]
-    fn pushpop_noinline(vec: &mut SmallVec<[u64; 16]>, x: u64) {
-        vec.push(x);
-        vec.pop();
-    }
-
-    b.iter(|| {
-        let mut vec: SmallVec<[u64; 16]> = SmallVec::new();
-        for x in 0..100 {
-            pushpop_noinline(&mut vec, x);
-        }
-        vec
-    });
-}
-
-#[bench]
-fn bench_macro_from_elem(b: &mut Bencher) {
-    b.iter(|| {
-        let vec: SmallVec<[u64; 16]> = smallvec![42; 100];
-        vec
-    });
-}
-
 #[bench]
 fn bench_macro_from_list(b: &mut Bencher) {
     b.iter(|| {
         let vec: SmallVec<[u64; 16]> = smallvec![
             0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 20, 24, 32, 36, 0x40, 0x80,
             0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000, 0x8000, 0x10000, 0x20000, 0x40000,
-            0x80000, 0x100000
+            0x80000, 0x100000,
         ];
         vec
     });
 }
-#[bench]
-fn bench_push_vec(b: &mut Bencher) {
-    #[inline(never)]
-    fn push_noinline(vec: &mut Vec<u64>, x: u64) {
-        vec.push(x)
-    }
-
-    b.iter(|| {
-        let mut vec: Vec<u64> = Vec::with_capacity(16);
-        for x in 0..100 {
-            push_noinline(&mut vec, x);
-        }
-        vec
-    });
-}
-
-#[bench]
-fn bench_insert_vec(b: &mut Bencher) {
-    #[inline(never)]
-    fn insert_noinline(vec: &mut Vec<u64>, x: u64) {
-        vec.insert(0, x)
-    }
-
-    b.iter(|| {
-        let mut vec: Vec<u64> = Vec::with_capacity(16);
-        for x in 0..100 {
-            insert_noinline(&mut vec, x);
-        }
-        vec
-    });
-}
-
-#[bench]
-fn bench_extend_vec(b: &mut Bencher) {
-    b.iter(|| {
-        let mut vec: Vec<u64> = Vec::with_capacity(16);
-        vec.extend(0..100);
-        vec
-    });
-}
-
-#[bench]
-fn bench_from_slice_vec(b: &mut Bencher) {
-    let v: Vec<u64> = (0..100).collect();
-    b.iter(|| {
-        let vec: Vec<u64> = Vec::from(&v[..]);
-        vec
-    });
-}
-
-#[bench]
-fn bench_extend_from_slice_vec(b: &mut Bencher) {
-    let v: Vec<u64> = (0..100).collect();
-    b.iter(|| {
-        let mut vec: Vec<u64> = Vec::with_capacity(16);
-        vec.extend_from_slice(&v);
-        vec
-    });
-}
-
-#[bench]
-fn bench_pushpop_vec(b: &mut Bencher) {
-    #[inline(never)]
-    fn pushpop_noinline(vec: &mut Vec<u64>, x: u64) {
-        vec.push(x);
-        vec.pop();
-    }
-
-    b.iter(|| {
-        let mut vec: Vec<u64> = Vec::with_capacity(16);
-        for x in 0..100 {
-            pushpop_noinline(&mut vec, x);
-        }
-        vec
-    });
-}
-
-#[bench]
-fn bench_macro_from_elem_vec(b: &mut Bencher) {
-    b.iter(|| {
-        let vec: Vec<u64> = vec![42; 100];
-        vec
-    });
-}
 
 #[bench]
 fn bench_macro_from_list_vec(b: &mut Bencher) {
@@ -221,7 +226,7 @@ fn bench_macro_from_list_vec(b: &mut Bencher) {
         let vec: Vec<u64> = vec![
             0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 20, 24, 32, 36, 0x40, 0x80,
             0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000, 0x8000, 0x10000, 0x20000, 0x40000,
-            0x80000, 0x100000
+            0x80000, 0x100000,
         ];
         vec
     });
diff --git a/lib.rs b/lib.rs
index 05fc4da..2869548 100644
--- a/lib.rs
+++ b/lib.rs
@@ -99,7 +99,7 @@ macro_rules! smallvec {
     ($elem:expr; $n:expr) => ({
         SmallVec::from_elem($elem, $n)
     });
-    ($($x:expr),*) => ({
+    ($($x:expr),*$(,)*) => ({
         SmallVec::from_slice(&[$($x),*])
     });
 }