Optimized special case of not matching the last char of the needle in BM string match.

* Special case for last char in BM-match
* Patch from Erik Corry to separate BM-algoritm into special case
  functions. Also changes condition for bailing out of simple search.
* Added simple search with no bailout for very short patterns.

[Lasse Reichstein, 2008-10-15 14:20:01]

Your patch, and some special cases.

[Lasse Reichstein, 2008-10-16 11:04:48]

Small code-review, reassigned due to vacation.

[Mads Ager (chromium), 2008-10-16 11:14:15]

LGTM

http://codereview.chromium.org/7349/diff/1/2
File src/runtime.cc (right):

http://codereview.chromium.org/7349/diff/1/2#newcode1263
Line 1263: if (pat.length() < 0) {
I don't understand this.  You assert above that pat.length() > 1, so how can you
get to a situation where pat.length() < 0?  I guess you mean to put in some
other constant here (please name the constant when you do).

[Lasse Reichstein, 2008-10-16 11:55:50]

Ignore extra patches, they are, contrary to what I thought, identical.

http://codereview.chromium.org/7349/diff/1/2
File src/runtime.cc (right):

http://codereview.chromium.org/7349/diff/1/2#newcode1263
Line 1263: if (pat.length() < 0) {
On 2008/10/16 11:14:15, Mads Ager wrote:
> I don't understand this.  You assert above that pat.length() > 1, so how can
you
> get to a situation where pat.length() < 0?  I guess you mean to put in some

Mea culpa. Should be 4, but I temporarily changed it to 1000 and 0 test
performance with and without, and uploaded the changelist before I set it back.
Good catch. 
> other constant here (please name the constant when you do).