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Java: Improve several join-orders #20088

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Merged
merged 3 commits into from
Jul 18, 2025
Merged

Java: Improve several join-orders #20088

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1273252
Java: Allow 2-column join on delta to improve join-order.
aschackmull Jul 18, 2025
7883124
Java: getSourceDeclaration() and getASourceSupertype*() commute and t…
aschackmull Jul 18, 2025
d9f47bd
Java: Improve join-order by properly annotating haveIntersection.
aschackmull Jul 18, 2025
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18 changes: 13 additions & 5 deletions java/ql/lib/semmle/code/java/Generics.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -521,7 +521,13 @@ private predicate unificationTargets(RefType t1, Type t2) {
t2 = a2.getComponentType()
)
or
exists(ParameterizedType pt1, ParameterizedType pt2, int pos |
unificationTargetsParameterized(_, _, t1, t2)
}

private predicate unificationTargetsParameterized(
ParameterizedType pt1, ParameterizedType pt2, RefType t1, RefType t2
) {
exists(int pos |
unificationTargets(pt1, pt2) and
t1 = pt1.getTypeArgument(pos) and
t2 = pt2.getTypeArgument(pos)
Expand Down Expand Up @@ -565,10 +571,12 @@ private predicate hasParameterSubstitution(
GenericType g1, ParameterizedType pt1, GenericType g2, ParameterizedType pt2, TypeVariable v,
RefType subst
) {
unificationTargets(pt1, pt2) and
exists(int pos | hasSubstitution(pt1.getTypeArgument(pos), pt2.getTypeArgument(pos), v, subst)) and
g1 = pt1.getGenericType() and
g2 = pt2.getGenericType()
exists(RefType t1, RefType t2 |
unificationTargetsParameterized(pt1, pt2, t1, t2) and
hasSubstitution(t1, t2, v, subst) and
g1 = pt1.getGenericType() and
g2 = pt2.getGenericType()
)
}

/**
Expand Down
11 changes: 9 additions & 2 deletions java/ql/lib/semmle/code/java/Type.qll
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Expand Up @@ -1261,14 +1261,21 @@ private Type erase(Type t) {
*
* For the definition of the notion of *erasure* see JLS v8, section 4.6 (Type Erasure).
*/
bindingset[t1, t2]
overlay[caller?]
pragma[inline]
pragma[inline_late]
predicate haveIntersection(RefType t1, RefType t2) {
exists(RefType e1, RefType e2 | e1 = erase(t1) and e2 = erase(t2) |
erasedHaveIntersection(e1, e2)
erasedHaveIntersectionFilter(e1, e2)
)
}

bindingset[t1, t2]
pragma[inline_late]
private predicate erasedHaveIntersectionFilter(RefType t1, RefType t2) {
erasedHaveIntersection(t1, t2)
}

/**
* Holds if there is no common (reflexive, transitive) subtype of the erasures
* of types `t1` and `t2`.
Expand Down
4 changes: 2 additions & 2 deletions java/ql/src/Likely Bugs/Collections/ContainsTypeMismatch.ql
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Expand Up @@ -103,8 +103,8 @@ class MismatchedContainerAccess extends MethodCall {
|
this.getCallee()
.getDeclaringType()
.getASourceSupertype*()
.getSourceDeclaration()
.getASourceSupertype*()
.hasQualifiedName(package, type) and
this.getCallee().getParameter(i).getType() instanceof TypeObject
)
Expand All @@ -119,7 +119,7 @@ class MismatchedContainerAccess extends MethodCall {
containerAccess(package, type, p, this.getCallee().getSignature(), i)
|
t = this.getCallee().getDeclaringType() and
t.getASourceSupertype*().getSourceDeclaration() = g and
t.getSourceDeclaration().getASourceSupertype*() = g and
g.hasQualifiedName(package, type) and
indirectlyInstantiates(t, g, p, result)
)
Expand Down