Documentation to Use SPARTA #3

ashispapu · 2019-02-28T11:57:36Z

Hi Team,

Thank you for releasing SPARTA. I am trying to explore different functionalities and APIs of SPARTA.However I am not able to find any document which explains the usage of SPARTA. Please let me know if there is any detailed document and examples to use SPARTA for different applications.
@int3 @facebook-github-bot , Any help is highly appreciated.
Thank you.
Ashis

arnaudvenet · 2019-03-05T19:00:39Z

All header files contain documentation and code snippets that explain how to use the various data structures. The unit test MonotonicFixpointIteratorTest shows how to set up a complete analysis (live variables) for a toy language.

Since SPARTA is programming-language independent, the documentation doesn't go into all the details of analyzing a real programming language. The Android bytecode optimizer Redex makes extensive use of SPARTA for its optimization passes and I would recommend browsing the code base for more realistic use cases. The interprocedural constant propagation would be a great example: it uses nearly every single data structure in SPARTA and it's also very well documented.

Summary: This diff introduces two main changes: ### Update Graph interface Currently, `predecessors` and `successors` in Graph trait returns `&[Self::EdgeId]`, this would be fairly efficient for Graph implementations that can return a slice. But I realized that in many cases, the Graph implementations may only be able to return an iterator (e.g., using petgraph). To make the interface more flexible, I decide to update it. There are three options for the new return type: ``` // 1. A iterator trait object (lazily evaluated, dynamic dispatch). fn predecessors(&self, n: Self::NodeId) -> Box<dyn Iterator<Item = Self::EdgeId> + '_>; // 2. Vector (heap alloc). fn predecessors(&self, n: Self::NodeId) -> Vec<Self::EdgeId>; // 3. SmallVec is similar to LLVM SmallVector, which can hold data in stack if its size is smaller than S. fn predecessors(&self, n: Self::NodeId) -> SmallVec<[Self::EdgeId; S]>; ``` With some benchmarking using different numbers of successors (etc.,1, 2, 4, 6, 8, 10), it turns out that the option #1 and #2 has similar performance, while option #3 is always slightly better than the other two. So I decided to adopt it. This will introduce a new dependency to our library but it's small. (later I can put this kind of benchmarking code in a separate bench folder.) ### Add a new trait for getting successor nodes In WPO, we need an interface to query the successor nodes of a given node. Previously I used a closure for it (while the C++ version uses std::function). After discussing with yuxuanchen1997, we think it's better to make this a separate trait to achieve this, so we add `SuccessorNodes` (The type that implements Graph trait can also implement Fn trait, but it's not recommended in Rust). In most cases, the same type can implement both. But they can also be separate types. In addition, this diff adds a naive graph implementation for testing. In this diff we only use it to test the `get_succ_nodes` interface. Reviewed By: yuxuanchen1997 Differential Revision: D38846203 fbshipit-source-id: 7951b83a7df6817b3796c1a4e40d85e08b4c2c12

ashispapu changed the title ~~Documenattion o Use SPARTA~~ Documentation to Use SPARTA Mar 1, 2019

arnaudvenet closed this as completed Mar 26, 2019

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Documentation to Use SPARTA #3

Documentation to Use SPARTA #3

ashispapu commented Feb 28, 2019 •

edited

arnaudvenet commented Mar 5, 2019

Documentation to Use SPARTA #3

Documentation to Use SPARTA #3

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ashispapu commented Feb 28, 2019 • edited

arnaudvenet commented Mar 5, 2019

ashispapu commented Feb 28, 2019 •

edited