code review 127450044: runtime: always pass type to mallocgc when allocating s...

runtime: always pass type to mallocgc when allocating scannable memory
We allocate scannable memory w/o type only in few places in runtime.
All these cases are not-performance critical (e.g. G or finq args buffer),
and in long term they all need to go away.
It's not worth it to have special code for this case in mallocgc.
So use special fake "notype" type for such allocations.

[dvyukov, 2014-08-18 14:00:54]

Hello golang-codereviews@googlegroups.com (cc: khr@golang.org, rlh@golang.org,
rsc@golang.org),

I'd like you to review this change to
https://dvyukov%40google.com@code.google.com/p/go/

[dvyukov, 2014-08-18 14:01:02]

https://codereview.appspot.com/127450044/diff/60001/src/pkg/runtime/malloc.go
File src/pkg/runtime/malloc.go (left):

https://codereview.appspot.com/127450044/diff/60001/src/pkg/runtime/malloc.go...
src/pkg/runtime/malloc.go:237: if typ != nil &&
(uintptr(typ.gc[0])|uintptr(typ.gc[1])) != 0 && uintptr(typ.size) > ptrSize {
this whole condition was removed

https://codereview.appspot.com/127450044/diff/60001/src/pkg/runtime/malloc.go...
src/pkg/runtime/malloc.go:283: if size == 2*ptrSize {
this block was removed

[khr, 2014-08-18 20:40:33]

LGTM.

[dvyukov, 2014-08-19 11:59:47]

*** Submitted as https://code.google.com/p/go/source/detail?r=6b52ebfb804e ***

runtime: always pass type to mallocgc when allocating scannable memory
We allocate scannable memory w/o type only in few places in runtime.
All these cases are not-performance critical (e.g. G or finq args buffer),
and in long term they all need to go away.
It's not worth it to have special code for this case in mallocgc.
So use special fake "notype" type for such allocations.

LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews, rlh, rsc
https://codereview.appspot.com/127450044