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C#: Speedup sameChildrenModuloTypeParameters() #1014

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Merged
calumgrant merged 1 commit into from
Mar 5, 2019
Merged

C#: Speedup sameChildrenModuloTypeParameters() #1014

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43 changes: 14 additions & 29 deletions csharp/ql/src/semmle/code/csharp/dispatch/Dispatch.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@ class DispatchCall extends Internal::TDispatchCall {

/** Internal implementation details. */
private module Internal {
private import semmle.code.csharp.Implements

cached
private module Cached {
/** Internal representation of calls. */
Expand Down Expand Up @@ -656,45 +658,28 @@ private module Internal {
or
y instanceof TypeParameter
or
// They must have the same kind.
(
x instanceof PointerType and y instanceof PointerType
or
x instanceof NullableType and y instanceof NullableType
or
x.(ArrayType).hasSameShapeAs(y.(ArrayType))
or
x.(ConstructedType).getUnboundGeneric() = y.(ConstructedType).getUnboundGeneric()
) and
// All of their corresponding children must be structurally equal
// All of the children must be structurally equal
sameChildrenModuloTypeParameters(x, y, x.getNumberOfChildren() - 1)
)
}

pragma[noinline]
private Type candidateInternalKind(Type t, Gvn::CompoundTypeKind k) {
result = candidateInternal(t) and
k = Gvn::getTypeKind(t)
}

/**
* Holds if the `i+1` first children of types `x` and `y` are equal
* modulo type parameters.
*/
pragma[nomagic]
private predicate sameChildrenModuloTypeParameters(Type x, Type y, int i) {
exists(Type xChild, Type yChild |
i = 0 and
candidateChildren(x, i, xChild, yChild) and
yChild = y.getChild(i) and
sameModuloTypeParameters(xChild, yChild)
)
i = -1 and
y = candidateInternalKind(x, Gvn::getTypeKind(y))
or
exists(Type xChild, Type yChild | sameChildrenModuloTypeParameters(x, y, i - 1) |
candidateChildren(x, i, xChild, yChild) and
yChild = y.getChild(i) and
sameModuloTypeParameters(xChild, yChild)
)
}

private predicate candidateChildren(Type x, int i, Type xChild, Type yChild) {
exists(Type y | y = candidateInternal(x) |
xChild = x.getChild(i) and
yChild = y.getChild(i)
)
sameChildrenModuloTypeParameters(x, y, i - 1) and
sameModuloTypeParameters(x.getChild(i), y.getChild(i))
}

/**
Expand Down