In prof. Jan Vitek JuliaCon 2021 keynote , he discussed type stability and grounded type (starting at 42:30). Short definitions given at this talk are as follow. Type is stable if we have clear relation between I/O types. Type is grounded when @code_warntype is green. I make a quick search of Juli…

[image] KZiemian: I want to ask is “grounded type” prof. Vitek term for something know in community or is it some new concept that doesn’t take roots outside core team (who is core team can be sometimes blurry)? This seems to be a term introduced by Prof. Vitek in their paper on type stabilit…

[image] Type Stability in Julia: Avoiding Performance Pathologies in JIT Compilation... As a scientific programming language, Julia strives for performance but also provides high-level productivity features. To avoid performance pathologies, Julia users are expected to adhere to a coding…

https://github.com/JuliaLang/julia/issues/39752

It should be noted, however, that “variables” in that definition refers to variables in the simplified single static assignment lowering of Julia code introduced in the paper and not to Julia surface level variables. The requirement for groundedness translated back to surface Julia syntax is probabl…

I understand what is lowered Julia code (I used @code_lowered few times), I have some understanding of “static” word in C++, but I can’t crack what it means “single static assignment lowering of Julia code”. Can you expand it a little bit?

Static single-assignment form - Wikipedia , a particular intermediate form that has desirable properties

They introduce a different lowering form in the paper that’s simpler and easier to prove things about. But the high-level take away is if you can predict the types of all expressions in a function from the types of its arguments, then there are a number of compiler optimizations that are provably gu…

What is grounded type in Julia?

Internals & Design

giordano January 13, 2022, 10:36pm 2

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What is grounded type in Julia?

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