At the beginning of a major GC cycle, select some mostly-empty pages to be evacuated. Mark the pages and the objects on these pages. Apply a write barrier for stores creating old -> evacuation candidate pointers, and discover any such pointers that already exist during marking.
At the end of a major GC cycle, evacuate objects from these pages. Forward pointers of objects in the remembered set and new-space. Free the evacuated pages.
This compaction is incremental in the sense that creating the remembered set is interleaved with mutator execution. The evacuation step, however, is stop-the-world.
Write-barrier elimination for x.slot = x is removed. Write-barrier elimination for x.slot = constant is removed in the JIT, kept for AOT but snapshot pages are marked as never-evacuate.
TEST=ci
Bug: https://github.com/dart-lang/sdk/issues/52513
Change-Id: Icbc29ef7cb662ef8759b8c1d7a63b7af60766281
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/357760
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Ryan Macnak
bc0f02e4c8