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CFG: Consider logical not a post order operation. #21811

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CFG: Consider logical not a post order operation. #21811

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CFG: Consider logical not a post order operation.
michaelnebel May 7, 2026
40a2148
C#: Introduce additional nodes to carry the boolean successor state.
michaelnebel May 8, 2026
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16 changes: 15 additions & 1 deletion shared/controlflow/codeql/controlflow/ControlFlowGraph.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -519,13 +519,14 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
or
n instanceof GotoStmt
or
n instanceof LogicalNotExpr
or
n instanceof Expr and
exists(getChild(n, _)) and
not Input1::preOrderExpr(n) and
not n instanceof LogicalAndExpr and
not n instanceof LogicalOrExpr and
not n instanceof NullCoalescingExpr and
not n instanceof LogicalNotExpr and
not n instanceof ConditionalExpr and
not n instanceof Switch and
not n instanceof Case
Expand Down Expand Up @@ -633,6 +634,10 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {

private string patternMatchTrueTag() { result = "[MatchTrue]" }

private string logicalNotTag(Boolean value) {
if value = true then result = "[LogicalNotTrue]" else result = "[LogicalNotFalse]"
}

/**
* Holds if an additional node tagged with `tag` should be created for
* `n`. Edges targeting such nodes are labeled with `t` and therefore `t`
Expand All @@ -648,6 +653,12 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
n instanceof PatternMatchExpr and
tag = patternMatchTrueTag() and
t.(BooleanSuccessor).getValue() = true
or
n instanceof LogicalNotExpr and
exists(Boolean b |
tag = logicalNotTag(b) and
t.(BooleanSuccessor).getValue() = b
)
}

/**
Expand Down Expand Up @@ -1456,6 +1467,9 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
or
exists(BooleanSuccessor t |
n1.isAfterValue(notexpr.getOperand(), t) and
n2.isAdditional(notexpr, logicalNotTag(t.getValue()))
or
n1.isAdditional(notexpr, logicalNotTag(t.getValue())) and
n2.isAfterValue(notexpr, t.getDual())
)
)
Expand Down
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