This recent GitHub reads like Julia doesn’t do common subexpression elimination at all, is this a correct assumption? Here’s the relevant bits from the issue: using BenchmarkTools f(x) = exp(x)/(1+exp(x)) function g(x) e = exp(x) e/(1 + e) end h!(f::F, v) where {F} = map!(f, v, v) @btime h!…

Yes, as you have very clearly demonstrated, and as is somewhat clearly stated in the issue you linked, julia does not typically do common subexpression elimination. There are some cases where it can do subespression elimination, but it’s probably best to just assume it never happens.

Does Julia do common subexpression elimination?

General Usage Performance

mbauman Split this topic August 17, 2023, 7:44pm 7

2 posts were split to a new topic: Towards implementing CSE in the Julia compiler

Topic		Replies	Views
A simple tool for common subexpression elimination Community package , announcement	2	1243	January 25, 2017
This month in Julia world - 2023-08 Newsletter	5	1910	August 27, 2023
Towards implementing CSE in the Julia compiler Internals	12	1321	August 21, 2023
No constant expression elimination for e.g. '2^24-1' Performance question	7	886	November 12, 2019
When does julia infer optimal code, when not? Performance question	4	685	November 16, 2018

Does Julia do common subexpression elimination?

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