cmpstring is too slow to use for equality and inequality

[robpike]

The code for

var a, b string
if a == b ...

calls runtime.cmpstring. If a and b are different lengths, equality could be tested
without even calling the function, or at least by calling a specialized equality tester.
 The cmpstring function scans the strings, which is usually unnecessary.

[robpike]

Comment 1:

I tried a trivial benchmark.  For two strings length 10 and 11, a==b takes 54ns on my
laptop while len(a)==len(b) && a==b takes only 2ns.  For 100-byte strings, it's 417ns
vs. 2ns.

[alberts]

Comment 2:

http://groups.google.com/group/golang-nuts/browse_thread/thread/f591ba36d83723c0

[rsc]

Comment 3:

2331045 fixed the issue Rob mentioned.
2317044 will fix the original issue raised on the mailing list
   (== when the strings are used as hash keys).
   It will also fix == when the strings are inside interface values.
   Leaving this open until I submit 2317044.

Status changed to Started.

[rsc]

Comment 4:

This issue was closed by revision 6235595.

Status changed to Fixed.