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[vm, gc] Incremental compaction.

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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>
This commit is contained in:
Ryan Macnak
2024-05-16 23:26:08 +00:00
committed by Commit Queue
parent 45221e51c3
commit bc0f02e4c8
42 changed files with 1695 additions and 144 deletions
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runtime/vm/raw_object.cc
+1 -5
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@@ -48,16 +48,12 @@ void UntaggedObject::Validate(IsolateGroup* isolate_group) const {
// Validate that the tags_ field is sensible.
uword tags = tags_;
if (IsNewObject()) {
if (!NewBit::decode(tags)) {
if (!NewOrEvacuationCandidateBit::decode(tags)) {
FATAL("New object missing kNewBit: %" Px "\n", tags);
}
if (OldAndNotRememberedBit::decode(tags)) {
FATAL("New object has kOldAndNotRememberedBit: %" Px "\n", tags);
}
} else {
if (NewBit::decode(tags)) {
FATAL("Old object has kNewBit: %" Px "\n", tags);
}
}
const intptr_t class_id = ClassIdTag::decode(tags);
if (!isolate_group->class_table()->IsValidIndex(class_id)) {