C++ IR: Support for global virtual dispatch #2638
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The IR data flow library now supports virtual dispatch with a library that's similar to `security.TaintTracking`. In particular, it should have the same performance characteristics. The main difference is that non-recursive callers of `flowsFrom` now pass `_` instead of `true` for `boolean allowFromArg`. This change allows flow through `return` to actually work.
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Performance is good on MySQL and facebookincubator/fizz. There's a lot of room for optimisation, but I'd like to find a database with bad performance before optimising. |
geoffw0
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Jan 17, 2020
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I'm pretty happy with this. I've asked a few questions to check my understanding.
I'd like to find a database with bad performance before optimising.
Yes - I imagine in many projects there just won't be enough DataSensitiveCalls for performance issues to manifest. Perhaps run select count(DataSensitiveCall dsc) on LGTM and see which projects come up top?
cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowDispatch.qll
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geoffw0
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Jan 17, 2020
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Better clarity was requested in the PR review.
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The IR data flow library now supports virtual dispatch with a library that's similar to
security.TaintTracking. In particular, it should have the same performance characteristics. The main difference is that non-recursive callers offlowsFromnow pass_instead oftrueforboolean allowFromArg. This change allows flow throughreturnto actually work.