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heap: add DCHECKs to SemiSpace::EnsureCurrentCapacity

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Adding some DCHECKs to document invariants and correctness properties
(e.g. pages with live objects aren't freed).

Bug: v8:12612
Change-Id: I543e4846c791320f3965561ae9d0b54739f5df03
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3507993
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79542}
This commit is contained in:
Omer Katz 2022-03-21 10:48:14 +01:00 committed by V8 LUCI CQ
parent cff529a2cd
commit 1ad10dbb81
1 changed files with 13 additions and 0 deletions
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13
src/heap/new-spaces.cc
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@ -39,6 +39,8 @@ bool SemiSpace::EnsureCurrentCapacity() {
if (IsCommitted()) {
const int expected_pages =
static_cast<int>(target_capacity_ / Page::kPageSize);
// `target_capacity_` is a multiple of `Page::kPageSize`.
DCHECK_EQ(target_capacity_, expected_pages * Page::kPageSize);
MemoryChunk* current_page = first_page();
int actual_pages = 0;
@ -49,9 +51,19 @@ bool SemiSpace::EnsureCurrentCapacity() {
current_page = current_page->list_node().next();
}
DCHECK_LE(actual_pages, expected_pages);
// Free all overallocated pages which are behind current_page.
while (current_page) {
DCHECK_EQ(actual_pages, expected_pages);
MemoryChunk* next_current = current_page->list_node().next();
// Promoted pages contain live objects and should not be discarded.
DCHECK(!current_page->IsFlagSet(Page::PAGE_NEW_NEW_PROMOTION));
// `current_page_` contains the current allocation area. Thus, we should
// never free the `current_page_`. Furthermore, live objects generally
// reside before the current allocation area, so `current_page_` also
// serves as a guard against freeing pages with live objects on them.
DCHECK_NE(current_page, current_page_);
AccountUncommitted(Page::kPageSize);
DecrementCommittedPhysicalMemory(current_page->CommittedPhysicalMemory());
memory_chunk_list_.Remove(current_page);
@ -83,6 +95,7 @@ bool SemiSpace::EnsureCurrentCapacity() {
static_cast<int>(current_page->area_size()),
ClearRecordedSlots::kNo);
}
DCHECK_EQ(expected_pages, actual_pages);
}
return true;
}