C++: Improve function pointer resolution #17788
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jketema
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Oct 17, 2024
cpp/ql/lib/change-notes/2024-10-16-new-api-for-call-target-resolution.md
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| * | ||
| * Note that `call` may be a call to a function pointer expression. | ||
| */ | ||
| Function getARuntimeTarget(Call call) { |
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I'm always slightly confused. Is DataFlowUtil the file whose contents users may still depend upon, although it's located in internal?
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Correct:
I don't know why this was done like this. This file structure is also present in the old AST dataflow, and we just copied it for IR dataflow.
We could actually change this, and maybe rename DataFlowUtil to DataFlowPublic to clear this confusion like it's been done for newer languages:
(although it looks like every language still stores the file in internal for some reason 🤔)
…olution.md Co-authored-by: Jeroen Ketema <93738568+jketema@users.noreply.github.com>
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This uses the existing "lambda resolution" mechanism in the dataflow library to resolve calls through function pointers.
We already track function addresses flowing into MaD models that specify a function pointer as an input (which was added in e9cd2dc). However, we never went the extra mile and added it when you call the function pointer in the source code.
This PR adds the one line which enables this. This should hopefully mean that we resolve a lot more function pointers.
Ideally, I would have liked to also remove the old function pointer resolution and virtual dispatch code, but since this is such a small change I think we should just get this improvement in now.
@bdrodes noted that he would also like for the call target resolution to be exposed as a predicate. I've snuck that into this PR in a99d576
All the results look like new genuine results with no performance problems in sight 🥳