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C++: Use the 'shortestDistances' HOP to count indirections instead of manual recursion. This avoids cyclic problems when we have invalid types.

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This commit is contained in:
Mathias Vorreiter Pedersen
2023-05-30 15:14:03 -07:00
committed by Arthur Baars
parent 1a0e3c8907
commit cc8aac5435
1 changed files with 18 additions and 13 deletions
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31
cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternalsCommon.qll
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@@ -139,6 +139,20 @@ class AllocationInstruction extends CallInstruction {
AllocationInstruction() { this.getStaticCallTarget() instanceof Cpp::AllocationFunction }
}
private predicate isIndirectionType(Type t) { t instanceof Indirection }
private predicate hasUnspecifiedBaseType(Indirection t, Type base) {
base = t.getBaseType().getUnspecifiedType()
}
/**
* Holds if `t2` is the same type as `t1`, but after stripping away `result` number
* of indirections.
* Furthermore, specifies in `t2` been deeply stripped and typedefs has been resolved.
*/
private int getNumberOfIndirectionsImpl(Type t1, Type t2) =
shortestDistances(isIndirectionType/1, hasUnspecifiedBaseType/2)(t1, t2, result)
/**
* An abstract class for handling indirections.
*
@@ -157,7 +171,10 @@ abstract class Indirection extends Type {
* For example, the number of indirections of a variable `p` of type
* `int**` is `3` (i.e., `p`, `*p` and `**p`).
*/
abstract int getNumberOfIndirections();
final int getNumberOfIndirections() {
result =
getNumberOfIndirectionsImpl(this.getType(), any(Type end | not end instanceof Indirection))
}
/**
* Holds if `deref` is an instruction that behaves as a `LoadInstruction`
@@ -195,19 +212,11 @@ private class PointerOrArrayOrReferenceTypeIndirection extends Indirection insta
PointerOrArrayOrReferenceTypeIndirection() {
baseType = PointerOrArrayOrReferenceType.super.getBaseType()
}
override int getNumberOfIndirections() {
result = 1 + countIndirections(this.getBaseType().getUnspecifiedType())
}
}
private class PointerWrapperTypeIndirection extends Indirection instanceof PointerWrapper {
PointerWrapperTypeIndirection() { baseType = PointerWrapper.super.getBaseType() }
override int getNumberOfIndirections() {
result = 1 + countIndirections(this.getBaseType().getUnspecifiedType())
}
override predicate isAdditionalDereference(Instruction deref, Operand address) {
exists(CallInstruction call |
operandForFullyConvertedCall(getAUse(deref), call) and
@@ -228,10 +237,6 @@ private module IteratorIndirections {
baseType = super.getValueType()
}
override int getNumberOfIndirections() {
result = 1 + countIndirections(this.getBaseType().getUnspecifiedType())
}
override predicate isAdditionalDereference(Instruction deref, Operand address) {
exists(CallInstruction call |
operandForFullyConvertedCall(getAUse(deref), call) and