Some large applications are bumping up against the 16-bit limit.
The object header changes from hash:32,cid:16,size:8,gc:8 to hash:32,cid:20,size:4,gc:8.
Because the CID field is no longer a power of two, it takes two instructions to load instead of one, increasing code size. The alternative change to cid:32,hash:24,gc:8 was considered and rejected because the reduction in hash bits very noticeably affects performance in applications with large data sets.
TEST=ci
Bug: b/255934984
Change-Id: I5fa36ba48a6852359d994393cf80c6a761c5d84c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/269120
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Ryan Macnak
9182d5e535