Bug 92679 – Structures should be swept after all other objects

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Mark Hahnenberg]

In order to get rid of ClassInfo from our objects, we need to be able to safely get the ClassInfo during the destruction of objects. We'd like to get the ClassInfo out of the Structure, but currently it is not safe to do so because the order of destruction of objects is not guaranteed to sweep objects before their corresponding Structure. We can fix this by sweeping Structures after everything else.

[Mark Hahnenberg]

Created attachment 155389 [details]
Patch

[Filip Pizlo]

Comment on attachment 155389 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=155389&action=review

> Source/JavaScriptCore/heap/HeapTimer.h:44
> +

Kill it with fire!

> Source/JavaScriptCore/heap/IncrementalSweeper.cpp:74
> +    return !m_blocksToSweep.size() || m_currentBlockToSweepIndex >= m_blocksToSweep.size();

I can has assert that m_currentBlockToSweepIndex <= m_blocksToSweep.size()

[Mark Hahnenberg]

Committed r124123: <http://trac.webkit.org/changeset/124123>

[Geoffrey Garen]

Comment on attachment 155389 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=155389&action=review

> Source/JavaScriptCore/heap/IncrementalSweeper.cpp:83
> +        MarkedBlock* block = m_blocksToSweep[m_currentBlockToSweepIndex];
> +        if (block->onlyContainsStructures()) {
> +            m_currentBlockToSweepIndex++;
> +            continue;

This logic gets a little whacky. Can't we just arrange for all the Structure blocks to be added to the array last, so we naturally sweep them last?

[WebKit Review Bot]

Re-opened since this is blocked by 92700

[Mark Hahnenberg]

Created attachment 155621 [details]
Patch

[Mark Hahnenberg]

Committed r124265: <http://trac.webkit.org/changeset/124265>