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	1225	January 25, 2017
No constant expression elimination for e.g. '2^24-1' Performance question	7	877	November 12, 2019
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Simplifying Symbolics.jl expression General Usage symbolics	2	120	September 3, 2024
Is the julia compiler smart enough to treat `x in (y,)` the same as `x == y`? Internals & Design question , performance	2	610	June 15, 2022

Does Julia do common subexpression elimination?

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