C++: Don't use GVN in AST DataFlow BarrierNode#2755
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It turns out that the evaluator will evaluate the GVN stage even when no predicate from it is needed after optimization of the subsequent stages. The GVN library is expensive to evaluate, and it'll become even more expensive when we switch its implementation to IR. This PR disables the use of GVN in `DataFlow::BarrierNode` for the AST data-flow library, which should improve performance when evaluating a single data-flow query on a snapshot with no cache. Precision decreases slightly, leading to a new FP in the qltests. There is no corresponding change for the IR data-flow library since IR GVN is not very expensive.
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This is the change I talked about in the team meeting yesterday. The |
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It turns out that the evaluator will evaluate the GVN stage even when no predicate from it is needed after optimization of the subsequent stages. The GVN library is expensive to evaluate, and it'll become even more expensive when we switch its implementation to IR.
This PR disables the use of GVN in
DataFlow::BarrierNodefor the AST data-flow library, which should improve performance when evaluating a single data-flow query on a snapshot with no cache. Precision decreases slightly, leading to a new FP in the qltests.There is no corresponding change for the IR data-flow library since IR GVN is not very expensive.