Restore HashMap performance by allowing some functions to be inlined

Since the hashmap and its hasher are implemented in different crates, we
currently can't benefit from inlining, which means that especially for
small, fixed size keys, there is a huge overhead in hash calculations,
because the compiler can't apply optimizations that only apply for these
keys.

Fixes the brainfuck benchmark in #24014.

diff --git a/src/libcore/hash/sip.rs b/src/libcore/hash/sip.rs
index be419e2cdadb0ed9c33a86eb708c6d513063f029..a92b72e0f00faa542598e1ccd7650277c9526902 100644 (file)
--- a/src/libcore/hash/sip.rs
+++ b/src/libcore/hash/sip.rs
@@ -111,6 +111,7 @@ pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
         state
     }
 
+    #[inline]
     fn reset(&mut self) {
         self.length = 0;
         self.v0 = self.k0 ^ 0x736f6d6570736575;
@@ -120,6 +121,7 @@ fn reset(&mut self) {
         self.ntail = 0;
     }
 
+    #[inline]
     fn write(&mut self, msg: &[u8]) {
         let length = msg.len();
         self.length += length;
@@ -173,6 +175,7 @@ fn write(&mut self, msg: &[u8]) {
         self.write(msg)
     }
 
+    #[inline]
     fn finish(&self) -> u64 {
         let mut v0 = self.v0;
         let mut v1 = self.v1;

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index ec130e8233a74ac51d55304f43ee7e81a7a03a30..f82c1653be1ae5697ed6c7f4a58395abae112553 100644 (file)
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -1600,6 +1600,7 @@ pub fn new() -> RandomState {
            reason = "hashing an hash maps may be altered")]
 impl HashState for RandomState {
     type Hasher = SipHasher;
+    #[inline]
     fn hasher(&self) -> SipHasher {
         SipHasher::new_with_keys(self.k0, self.k1)
     }