code review 4515167: gc: elide call to runtime.closure for function literals...

gc: elide call to runtime.closure for function literals called in-place.

before:
runtime_test.BenchmarkCallClosure        5000000               499 ns/op
runtime_test.BenchmarkCallClosure1       5000000               681 ns/op

after:
runtime_test.BenchmarkCallClosure       500000000                5 ns/op
runtime_test.BenchmarkCallClosure1       10000000              160 ns/op

[lvd, 2011-05-31 16:28:03]

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

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2011-05-31 17:24:49]

LGTM

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/closure.c
File src/cmd/gc/closure.c (right):

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/closure.c#newcode231
src/cmd/gc/closure.c:231: // An extra zero, to fill the dummy return pointer
slot
This block might simplify to

ll = list(ll, nodintconst(0));

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/walk.c
File src/cmd/gc/walk.c (right):

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/walk.c#newcode777
src/cmd/gc/walk.c:777: 
delete blank line here and two lines below?

[rsc, 2011-05-31 17:26:30]

in CL desc s/Elide/elide/
before you check it in, would be nice to add a benchmark in package runtime

[lvd, 2011-05-31 17:30:07]

all done.

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/closure.c
File src/cmd/gc/closure.c (right):

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/closure.c#newcode231
src/cmd/gc/closure.c:231: // An extra zero, to fill the dummy return pointer
slot
On 2011/05/31 17:24:49, rsc wrote:
> This block might simplify to
> 
> ll = list(ll, nodintconst(0));

then i'd have to re-typecheck.

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/walk.c
File src/cmd/gc/walk.c (right):

http://codereview.appspot.com/4515167/diff/3/src/cmd/gc/walk.c#newcode777
src/cmd/gc/walk.c:777: 
On 2011/05/31 17:24:49, rsc wrote:
> delete blank line here and two lines below?

Done.

[lvd, 2011-05-31 17:41:41]

benchmark results before:

runtime_test.BenchmarkCallClosure        5000000               521 ns/op

after:

runtime_test.BenchmarkCallClosure       500000000                7 ns/op

[lvd, 2011-05-31 18:52:23]

*** Submitted as http://code.google.com/p/go/source/detail?r=47f1627ee6a5 ***

gc: elide call to runtime.closure for function literals called in-place.

before:
runtime_test.BenchmarkCallClosure        5000000               499 ns/op
runtime_test.BenchmarkCallClosure1       5000000               681 ns/op

after:
runtime_test.BenchmarkCallClosure       500000000                5 ns/op
runtime_test.BenchmarkCallClosure1       10000000              160 ns/op

R=rsc
CC=golang-dev
http://codereview.appspot.com/4515167