[PATCH] D116370: [clang][dataflow] Add multi-variable constant propagation example.

Thu Dec 30 09:24:41 PST 2021

xazax.hun accepted this revision.
xazax.hun added a comment.
This revision is now accepted and ready to land.

In D116370#3213191 <https://reviews.llvm.org/D116370#3213191>, @ymandel wrote:

> In D116370#3213120 <https://reviews.llvm.org/D116370#3213120>, @xazax.hun wrote:
>
>> Does it make sense to have both the single and multi variable tracking tests? Or do we want to have these as some sort of steps in a tutorial?
>
> Right -- the intent in keeping the original one was for an (eventual) tutorial.  For that matter, if you think there's changes I should make to the single variable version to bring them closer together, I'd be happy to do that.

I think from the tutorial's point of view that would be awesome! But I'm also happy with doing that in a follow-up PR some later time.

================
Comment at: clang/unittests/Analysis/FlowSensitive/MultiVarConstantPropagationTest.cpp:53
+  };
+  // `State` determines the meaning of the lattice when `Value` is `None`:
+  //  * `Undefined` -> bottom,
----------------
If `ValueSate` only makes sense when `Value` is none, this almost looks like a `std::variant<ValueState, int64_t>`. Unfortunately, as far as I understand LLVM is not at C++17 yet. I did not find an equivalent structure in the LLVM support library, but in case you agree, I think we could leave a TODO to change this after the C++ standard requirement was raised.

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https://reviews.llvm.org/D116370