fix and reduce the risk of GC-arena related leaks #701
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…ad of pushing down the arena value to let callees restore the state upon return
kazuho
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Jan 14, 2016
fix and reduce the risk of GC-arena related leaks
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Current design pushes down the arena value to callees so that they could restore the arena when operation is complete. The positive side of the design is that it would help us restore the arena earlier, and that there is more chance of callees getting tail-call optimized. The downside is that we need to assert that the arena is restored in more code paths.
As has been reported in #699, we have failed to assert that the arena is always being restored. I have found that such code is also missing here.
Now that we have found multiple occurrences of such failures we should switch to a more conservative design: maintain GC arena at the highest level; i.e. restore the GC state within the functions that collect the GC state. With the change, the code paths involved to handling the GC arena decreases, thereby it becomes easier for us to audit the code.