runtime: faster string equality.

benchmark                                old ns/op    new ns/op    delta
BenchmarkCompareStringEqual                     51           35  -30.20%
BenchmarkCompareStringIdentical                 51            7  -85.71%
BenchmarkCompareStringSameLength                25           18  -28.29%
BenchmarkCompareStringDifferentLength            2            2   +1.46%

R=golang-dev, rsc
CC=golang-dev, remy
https://golang.org/cl/6450092

1 files changed, 20 insertions, 0 deletions

diff --git a/src/pkg/runtime/string.goc b/src/pkg/runtime/string.goc
index 7cab6d2417..b72a1aa5e7 100644
--- a/src/pkg/runtime/string.goc
+++ b/src/pkg/runtime/string.goc
@@ -204,6 +204,26 @@ func cmpstring(s1 String, s2 String) (v int32) {
 	v = cmpstring(s1, s2);
 }
 
+func eqstring(s1 String, s2 String) (v bool) {
+	uint32 i, l;
+
+	if(s1.len != s2.len) {
+		v = false;
+		return;
+	}
+	if(s1.str == s2.str) {
+		v = true;
+		return;
+	}
+	l = s1.len;
+	for(i=0; i<l; i++)
+		if(s1.str[i] != s2.str[i]) {
+			v = false;
+			return;
+		}
+	v = true;
+}
+
 int32
 runtime·strcmp(byte *s1, byte *s2)
 {