Move the Kernel string offsets into the VM's heap.

Move the Kernel string offsets into the VM's heap.

Copy the Kernel string offsets into a uint32 array in the VM's heap.
This avoids allocating small string objects with new and avoids having
a table of the canonical strings.

Instead of an offset and a size, strings are now represented as
indexes into the string table in the heap.  The start offset of string
N is found at byte offset N*4 because it is a uint32, and the end
offset is found at byte offset (N+1)*4.  The strings themselves are
just integer indexes instead of pointers.

In the stream flow graph builder, string access is all random access.

R=jensj@google.com, vegorov@google.com

Committed: https://github.com/dart-lang/sdk/commit/865e0669b2320688eaa7bf23b06aee780e094076

[Kevin Millikin (Google), 2017-05-01 21:06:22]

kmillikin@google.com changed reviewers:
+ asiva@google.com, jensj@google.com, vegorov@google.com

[jensj, 2017-05-02 07:26:25]

lgtm

[Vyacheslav Egorov (Google), 2017-05-02 12:48:34]

LGTM

https://codereview.chromium.org/2852943003/diff/1/runtime/vm/kernel_to_il.cc
File runtime/vm/kernel_to_il.cc (right):

https://codereview.chromium.org/2852943003/diff/1/runtime/vm/kernel_to_il.cc#...
runtime/vm/kernel_to_il.cc:1068: return string_offsets_.GetUint32((string_index
+ 1) << 2) -
StringOffset(string_index + 1) - StringOffset(string_index);

[Kevin Millikin (Google), 2017-05-02 15:36:02]

Description was changed from

==========
Move the Kernel string offsets into the VM's heap.

Copy the Kernel string offsets into a uint32 array in the VM's heap.
This avoids allocating small string objects with new and avoids having
a table of the canonical strings.

Instead of an offset and a size, strings are now represented as
indexes into the string table in the heap.  The start offset of string
N is found at byte offset N*4 because it is a uint32, and the end
offset is found at byte offset (N+1)*4.  The strings themselves are
just integer indexes instead of pointers.

In the stream flow graph builder, string access is all random access.
==========

to

==========
Move the Kernel string offsets into the VM's heap.

Copy the Kernel string offsets into a uint32 array in the VM's heap.
This avoids allocating small string objects with new and avoids having
a table of the canonical strings.

Instead of an offset and a size, strings are now represented as
indexes into the string table in the heap.  The start offset of string
N is found at byte offset N*4 because it is a uint32, and the end
offset is found at byte offset (N+1)*4.  The strings themselves are
just integer indexes instead of pointers.

In the stream flow graph builder, string access is all random access.

R=jensj@google.com, vegorov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/865e0669b2320688eaa7bf23b06aee780e094076
==========

[Kevin Millikin (Google), 2017-05-02 15:36:07]

Committed patchset #2 (id:20001) manually as
865e0669b2320688eaa7bf23b06aee780e094076 (presubmit successful).

[Kevin Millikin (Google), 2017-05-03 00:07:47]

https://codereview.chromium.org/2852943003/diff/1/runtime/vm/kernel_to_il.cc
File runtime/vm/kernel_to_il.cc (right):

https://codereview.chromium.org/2852943003/diff/1/runtime/vm/kernel_to_il.cc#...
runtime/vm/kernel_to_il.cc:1068: return string_offsets_.GetUint32((string_index
+ 1) << 2) -
On 2017/05/02 12:48:34, Vyacheslav Egorov (Google) wrote:
> StringOffset(string_index + 1) - StringOffset(string_index);

Thanks for spotting this.