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C#: Fix performance issue with UselessNullCoalescingExpression query.

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This commit is contained in:
Michael Nebel
2022-03-14 13:16:28 +01:00
parent 432ac7a824
commit ba67ea0445
1 changed files with 12 additions and 4 deletions
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16
csharp/ql/src/Language Abuse/UselessNullCoalescingExpression.ql
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@@ -14,11 +14,19 @@
import csharp
import semmle.code.csharp.commons.StructuralComparison
pragma[noinline]
private predicate same(AssignableAccess x, AssignableAccess y) {
exists(NullCoalescingExpr nce |
x = nce.getLeftOperand() and
y = nce.getRightOperand().getAChildExpr*()
) and
sameGvn(x, y)
}
private predicate uselessNullCoalescingExpr(NullCoalescingExpr nce) {
forex(AssignableAccess y |
y = nce.getRightOperand().getAChildExpr*() and sameGvn(nce.getLeftOperand(), y)
|
y instanceof AssignableRead and not y.isRefArgument()
exists(AssignableAccess x |
nce.getLeftOperand() = x and
forex(AssignableAccess y | same(x, y) | y instanceof AssignableRead and not y.isRefArgument())
)
}