C++: Make unresolve dispatch on result
#242
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This change means that there are no results for `unresolveElement(t)` where `t` is a "junk type" -- a class definition that is not in the image of `resolveClass`. These "junk types" still exist as `Element`s, but they will never be returned by any predicate that goes through `unresolveElement` to query the db. We get a small reduction in DIL size and a significant speed improvement. The DIL for `NewArrayDeleteMismatch.ql` is reduced from 27,630 lines to 27,507 lines, and the total analysis time for the LGTM suite on jdk8u is reduced from 1158s to 984s.
The change to make `unresolveElement` a member predicate was helpful for the optimiser when it dispatched on `this`, but now that it "dispatches" on `result` it's just an unnecessary pollution of the `ElementBase` namespace.
ian-semmle
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Sep 27, 2018
smowton
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Feb 7, 2022
Add fallback symbol lookup for IrFunctionReference extraction
MathiasVP
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Aug 10, 2025
…e-fix added hasbranchedge
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This change means that there are no results for
unresolveElement(t)wheretis a "junk type" -- a class definition that is not in the image ofresolveClass. These "junk types" still exist asElements, but they will never be returned by any predicate that goes throughunresolveElementto query the db.We get a small reduction in DIL size and a significant speed improvement. The DIL for
NewArrayDeleteMismatch.qlis reduced from 27,630 lines to 27,507 lines, and the total analysis time for the LGTM suite on jdk8u is reduced from 1158s to 984s. This makes it faster than 1.17.2 on jdk8u, even when disregarding the one query where 1.17.2 has a serious performance problem.This change is in quite similar to #215. The main difference is that the inlined type check is (effectively)
t instanceof @usertypeinstead ofisClass(t), and the former is much easier for the optimiser to eliminate statically.