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Guards: Improve performance of forall in guardDeterminesPhiInput. #21408

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aschackmull merged 2 commits into from
Mar 5, 2026
+6 −2
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Guards: Improve performance of forall in guardDeterminesPhiInput. #21408

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ad5ab9f
Gaurds: Improve perf of forall in guardDeterminesPhiInput.
aschackmull Mar 4, 2026
37a8fc8
Guards: Use unique aggregate.
aschackmull Mar 5, 2026
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8 changes: 6 additions & 2 deletions shared/controlflow/codeql/controlflow/Guards.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -640,7 +640,11 @@ module Make<
Guard guard, GuardValue v, SsaPhiDefinition phi, Expr input
) {
exists(GuardValue dv, SsaExplicitWrite inp |
guardControlsPhiBranch(guard, v, phi, inp) and
// The `forall` below implies that there's only one `inp` guarded by
// `guard == v`, but checking this upfront using `unique` as opposed to
// merely stating `guardControlsPhiBranch(guard, v, phi, inp)` improves
// performance of the `forall` check.
inp = unique(SsaDefinition inp0 | guardControlsPhiBranch(guard, v, phi, inp0)) and
inp.getValue() = input and
dv = v.getDualValue() and
forall(SsaDefinition other | phi.hasInputFromBlock(other, _) and other != inp |
Expand Down Expand Up @@ -741,7 +745,7 @@ module Make<
possibleValue(v, false, e, k) and
not possibleValue(v, true, e, k) and
// there's only one expression with the value `k`
1 = strictcount(Expr e0 | possibleValue(v, _, e0, k)) and
e = unique(Expr e0 | possibleValue(v, _, e0, k)) and
// and `v` has at least two possible values
2 <= strictcount(GuardValue k0 | possibleValue(v, _, _, k0))
}
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