WebAssembly / WebAssembly/binaryen
Speed up LocalGraph
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- Dominant language
- WebAssembly
- Stars
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- Forks
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- Avg merge
- 1d 19h
- Merged PRs (30d)
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Description
src/ir/local-graph.h is fairly slow, and we should make it faster. If it were fast enough, we could enable precompute-propagate and merge-locals in more optimization levels, which would improve code output quality.
What LocalGraph does is scan a function and produce a mapping of the sets affecting each get. That is, for each get, the sets that reach that get, that their assigned value may be read there.
This is similar to SSA computation in a way, but simpler (no need to create phis), and there are fairly fast SSA computations on structured control flow like ours, so it seems like this could be fairly fast. Right now the implementation naively carries around big data structures needlessly.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with src/ir/local-graph.h and trace how LocalGraph scans functions and carries the sets reaching each get. Compare its data flow with fast SSA computation on structured control flow, as suggested in the issue. Done means LocalGraph is measurably faster enough to consider enabling precompute-propagate and merge-locals at more optimization levels.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp, wasm
- Domain
- compilers, performance
- Issue type
- Refactor
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100