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[#2143] Optimize aggregation pass

Leonid Vasilev requested to merge dk318/#2143-optimize-ast-aggregated into dev

Motivation and Context


Aggregation pass takes too much time for checker-ligo contract. Let's optimize it.


Do the following optimizations:

  1. Use Ast_typed type expressions in ast_aggregated and move the former one to the expansion. This saves ~1.1G cycles in aggregation but expansion takes ~30M cycles more.
  2. Replace associative lists in exp with maps.
  3. Strip lst @ [ elt ] antipattern.

All these optimizations reduce cycles from 2.47G to 226.57M.

Related issues

Resolves a part of #2143 .

Checklist for the LIGO Language Server

  • I checked whether I need to update the file for the plugin and did so if necessary:
    • If I implemented a new LSP request, I added it to the list of supported features that may be disabled
    • If I implemented a new LSP method, I added it to the list of supported functionality
  • I checked that my changes work in Emacs, Vim, and Visual Studio Code
  • (Before merging) The commit history is squashed and prettified, and follows the Serokell commit policy, or the MR is set to squash the commits



  • compiler
  • website
  • webide
  • vscode-plugin
  • debugger

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Performance improvement (non-breaking change that improves performance)
  • None (change with no changelog)


Improved performance for LSP and compilation pipeline.

The LSP should now take less time between keystrokes.

This is done by optimizing aggregation pass.


  • Changes follow the existing coding style (use dune @fmt to check).
  • Tests for the changes have been added (for bug fixes / feature).
  • Documentation has been updated.
  • Changelog description has been added (if appropriate).
  • Start titles under ## Changelog section with #### (if appropriate).
  • There is no image or uploaded file in changelog
  • Examples in changed behaviour have been added to the changelog (for breaking change / feature).

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