tweag/asterius

Make use of precomputed `Int` and `Char` closures in the runtime

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#331 opened on Oct 20, 2019

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P2good first issuetype: bug

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Description

The ghc rts has precomputed Int and Char closures for small Int and Char values. When the garbage collector finds an Int or Char closure in the dynamic memory which fall into the range, the closure is replaced with a precomputed closure. This trick is based on the assumption that a lot of such closures actually contain small values, and can slightly improve the gc efficiency. We don't implement this trick for now, but it shouldn't be too hard to do so; additionally, rts_mk* functions can also return precomputed closures directly.

Contributor guide

Research direction
Study the GHC RTS implementation of precomputed closures for Int and Char, then locate the equivalent code in the Asterius runtime and apply the optimization.
Tech stack
c
Domain
backend
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
CGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50