[orc] Avoid pathological propogation order #107488
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In certain pathological object files we were getting extremely slow linking because we were repeatedly propogating dependencies to the same blocks instead of accumulating as many changes as possible. Change the order of iteration so that we go through every node in the worklist before returning to any previous node, reducing the number of expensive dependency iterations. In practice, this took one case from 60 seconds to 2 seconds. Note: the performance is still non-deterministic, because the block order itself is non-deterministic. rdar://133734391
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In certain pathological object files we were getting extremely slow linking because we were repeatedly propogating dependencies to the same blocks instead of accumulating as many changes as possible. Change the order of iteration so that we go through every node in the worklist before returning to any previous node, reducing the number of expensive dependency iterations.
In practice, this took one case from 60 seconds to 2 seconds. Note: the performance is still non-deterministic, because the block order itself is non-deterministic.
rdar://133734391