code review 206060: runtime: tighten garbage collector

runtime: tighten garbage collector
 * specialize sweepspan as sweepspan0 and sweepspan1.
 * in sweepspan1, inline "free" to avoid expensive mlookup.

[rsc, 2010-02-10 09:16:58]

Hello iant (cc: golang-dev@googlegroups.com),

I'd like you to review this change.

[iant, 2010-02-10 16:28:56]

LGTM

http://codereview.appspot.com/206060/diff/1001/4
File src/pkg/runtime/mgc0.c (right):

http://codereview.appspot.com/206060/diff/1001/4#newcode207
src/pkg/runtime/mgc0.c:207: if(pfinq->fn == nil)
Trailing tab.

http://codereview.appspot.com/206060/diff/1001/4#newcode220
src/pkg/runtime/mgc0.c:220: // Must match computation in MCentral_Grow.
Now that this is done three times, should it be a macro?

http://codereview.appspot.com/206060/diff/1001/4#newcode226
src/pkg/runtime/mgc0.c:226: ref = gcrefp[i];
This will probably be a hot loop; will 6c generate better code if you do put
gcrefp++ in the for clause and use *gcrefp rather than gcrefp[i]?  (For gcc it
wouldn't matter.)

http://codereview.appspot.com/206060/diff/1001/4#newcode229
src/pkg/runtime/mgc0.c:229: pp = p+i*size;
Here too: perhaps better to initialize pp to p and then add size each time
through the loop.

[rsc, 2010-02-10 22:59:47]

*** Submitted as http://code.google.com/p/go/source/detail?r=b2c1bb614c58 ***

runtime: tighten garbage collector
 * specialize sweepspan as sweepspan0 and sweepspan1.
 * in sweepspan1, inline "free" to avoid expensive mlookup.

R=iant
CC=golang-dev
http://codereview.appspot.com/206060