[PATCH] D104268: [ptr_provenance] Introduce optional ptr_provenance operand to load/store

[Ralf via Phabricator via llvm-commits]

RalfJung added inline comments.


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Comment at: llvm/docs/LangRef.rst:9988-9991
+The optional ``ptr_provenance`` argument, when present, specifies a separate
+pointer provenance path for the ``pointer`` operand of the ``load`` instruction.
+See :ref:`Pointer Provenance<_ptr_provenance>`. When it is not present, the
+``pointer`` operand can be used for the pointer provenance.
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Rust and C also have a notion of "pointer provenance", but it is subtly difference: provenance in those languages is something that flows with pointer values. IOW, a value of pointer type consists of some address in memory, plus some "provenance" metadata. LLVM also has that kind of provenance, it is needed e.g. to explain some of the behavior of getelementptr. (A pointer returned by getelementptr without inbounds can go out-of-bounds but must not be used to access memory outside the bounds of the allocation it started with. In other words, the pointer "remembers" the allocation it is associated with in some way that is separate from the integer address it points to.)

Is it a good idea to use the same term for this slightly different concept? A load operation already receives provenance from its pointer argument, and now with this patchset it *also* receives something else, but also called provenance, via a separate argument.


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  https://reviews.llvm.org/D104268/new/

https://reviews.llvm.org/D104268