reactorlabs/rir

sequences starting with non-constant value

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#789 opened on Jan 22, 2020

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enhancementgood first issuehelp wantedpir

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Description

For some reason in https://github.com/reactorlabs/rir/blob/master/rir/src/ir/Compiler.cpp#L238 we only properly compile a simple for loop for (i in a:b) if a is a numerical constant.

This causes us to allocate lots of unnecessary vectors (e.g. in nbody_naive_2).

I suspect that this is a hack, exploiting the fact that a < b happens to error similarly to a:b if a is a number.

This should be fixable quite easily by emitting a check for the type of a ensuring that it is compatible with : first.

Contributor guide

Research direction
Inspect Compiler.cpp around line 238 to understand the current handling of `for (i in a:b)`. Identify where the type check for `a` should be emitted to ensure compatibility with `:` operator. Then implement a type check before the sequence generation.
Tech stack
cpp
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85