Shave 39% from snapshot size.

Shave 39% from snapshot size.
Committed: http://code.google.com/p/v8/source/detail?r=9722

[Lasse Reichstein, 2011-10-20 10:06:54]

LGTM

http://codereview.chromium.org/8344079/diff/1/src/heap.h
File src/heap.h (right):

http://codereview.chromium.org/8344079/diff/1/src/heap.h#newcode67
src/heap.h:67: V(Map, global_property_cell_map, GlobalPropertyCellMap)          
           \
Is this ordering change just due to "popularity", or is there another reason?
(In 64-bit code, we generate shorter code for accessing the first 32 elements,
in 32-bit code it's the first 64, so this changes which elements that is).

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc
File src/serialize.cc (right):

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc#newcode923
src/serialize.cc:923: *current++ = isolate->heap()->roots_address()[root_id];
The name roots_address suggests that it returns an Address. Could it be called
roots_array_start or _origin instead?

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc#newcode1325
src/serialize.cc:1325: root_index < 0x20 &&
Name the constants.

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc#newcode1435
src/serialize.cc:1435: if (repeat_count > kMaxRepeats) {
A generic repeat takes five bytes. Up to 4*kMaxRepeats, it's smaller to do
repeated constant repeats.

http://codereview.chromium.org/8344079/diff/1/src/serialize.h
File src/serialize.h (right):

http://codereview.chromium.org/8344079/diff/1/src/serialize.h#newcode488
src/serialize.h:488: void set_root_index_wave_front(int value) {
root_index_wave_front_ = value; }
Assert that the wave-front moves forward?

[Erik Corry, 2011-10-20 11:01:42]

http://codereview.chromium.org/8344079/diff/1/src/heap.h
File src/heap.h (right):

http://codereview.chromium.org/8344079/diff/1/src/heap.h#newcode67
src/heap.h:67: V(Map, global_property_cell_map, GlobalPropertyCellMap)          
           \
On 2011/10/20 10:06:54, Lasse Reichstein wrote:
> Is this ordering change just due to "popularity", or is there another reason?
> (In 64-bit code, we generate shorter code for accessing the first 32 elements,
> in 32-bit code it's the first 64, so this changes which elements that is).

It's due to popularity in the snapshot.  The first 32 are encoded in just one
byte.

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc
File src/serialize.cc (right):

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc#newcode923
src/serialize.cc:923: *current++ = isolate->heap()->roots_address()[root_id];
On 2011/10/20 10:06:54, Lasse Reichstein wrote:
> The name roots_address suggests that it returns an Address. Could it be called
> roots_array_start or _origin instead?

Done.

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc#newcode1325
src/serialize.cc:1325: root_index < 0x20 &&
On 2011/10/20 10:06:54, Lasse Reichstein wrote:
> Name the constants.

Done.

http://codereview.chromium.org/8344079/diff/1/src/serialize.cc#newcode1435
src/serialize.cc:1435: if (repeat_count > kMaxRepeats) {
On 2011/10/20 10:06:54, Lasse Reichstein wrote:
> A generic repeat takes five bytes. Up to 4*kMaxRepeats, it's smaller to do
> repeated constant repeats.

No, a generic repeat takes 2 bytes if the repeat count is less than 128.

http://codereview.chromium.org/8344079/diff/1/src/serialize.h
File src/serialize.h (right):

http://codereview.chromium.org/8344079/diff/1/src/serialize.h#newcode488
src/serialize.h:488: void set_root_index_wave_front(int value) {
root_index_wave_front_ = value; }
On 2011/10/20 10:06:54, Lasse Reichstein wrote:
> Assert that the wave-front moves forward?

Done.