The `AliasedUse` instruction is supposed to represent future uses of aliased memory after the function returns. Since local variables from that function are no longer allocated after the function returns, the `AliasedUse` instruction should access only the set of aliased locations that does not include locals from the current stack frame.
This new instruction is the dual of the existing `AliasedDefinition` instruction. Whereas that instruction defines the contents of aliased memory before the function was called, `AliasedUse` represents the potential use of all aliased memory after the function returns. This ensures that writes to aliased memory do not appear "dead", even if there are no further reads from aliased memory within the function itself.
The one interesting piece that needed to be fixed up was the type of an `Indirect[Read|Write]SideEffect` operand/result. If the parameter type is a pointer or reference to an incomplete type, we need to set the type of the side effect memory access to `Unknown`, because we don't model incomplete types in the IR type system.
I also added minimal support for `__assume` (generated as a `NoOp`), because lack of `__assume` support got in the way of debugging the other issue above.
Eventually these files will subsume the current `queries.xml` files
at the top of query-containing and library directories. For now they're
just here to support internal testing of the tooling support for them
we're writing on.
Format and contents is a work in progress. If you're not in Semmle,
don't depend on anything here making sense (or staying stable) until
you see the version tags increase to something nonzero.
