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outlining a predicate to give hints about join ordering

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This commit is contained in:
Erik Krogh Kristensen
2020-01-17 13:42:08 +01:00
parent 6ad62e32e0
commit a25c5d7090
1 changed files with 15 additions and 6 deletions
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21
javascript/ql/src/semmle/javascript/dataflow/Configuration.qll
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@@ -318,16 +318,12 @@ abstract class BarrierGuardNode extends DataFlow::Node {
*
* INTERNAL: this predicate should only be used from within `blocks(boolean, Expr)`.
*/
pragma[noinline,nomagic]
predicate internalBlocks(DataFlow::Node nd, string label) {
// 1) `nd` is a use of a refinement node that blocks its input variable
exists(SsaRefinementNode ref, boolean outcome |
nd = DataFlow::ssaDefinitionNode(ref) and
forex(SsaVariable input | input = ref.getAnInput() |
getEnclosingExpr() = ref.getGuard().getTest() and
outcome = ref.getGuard().(ConditionGuardNode).getOutcome() and
barrierGuardBlocksExpr(this, outcome, input.getAUse(), label)
)
outcome = ref.getGuard().(ConditionGuardNode).getOutcome() and
ssaRefinementBlocks(outcome, ref, label)
)
or
// 2) `nd` is an instance of an access path `p`, and dominated by a barrier for `p`
@@ -337,8 +333,21 @@ abstract class BarrierGuardNode extends DataFlow::Node {
outcome = cond.getOutcome() and
barrierGuardBlocksAccessPath(this, outcome, p, label) and
cond.dominates(bb)
)
}
/**
* Holds if there exists an input variable of `ref` that blocks the label `label`.
*
* This predicate is outlined to give the optimizer a hint about the join ordering.
*/
private predicate ssaRefinementBlocks(boolean outcome, SsaRefinementNode ref, string label) {
getEnclosingExpr() = ref.getGuard().getTest() and
forex(SsaVariable input | input = ref.getAnInput() |
barrierGuardBlocksExpr(this, outcome, input.getAUse(), label)
)
}
/**
* Holds if this node blocks expression `e` provided it evaluates to `outcome`.