4 ms·

If ifs and buts were candy and nuts...

kruxigt 4y ago
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markkitti 4y ago
This becomes an important part of optimizing Julia code. There is some tooling for this. Below, identity is a type stable function because we know that an Int64 argument results in a Int64 output. The macro code_warntype reveals the type analysis: ``` julia> @code_warntype identity(5) MethodInstance for identity(::Int64) from identity(x) @ Base operators.jl:513 Arguments #self#::Core.Const(identity) x::Int64 Body::Int64 1 ─ nothing └── return x ``` This is type unstable and results in dynamic dispatch because we are not sure if the argument to identity will be an Int64 or a Float64. ``` julia> f(x) = identity(x ≥ 0 ? x : x + 0.0) f (generic function with 1 method) julia> @code_warntype f(5) MethodInstance for f(::Int64) from f(x) @ Main REPL[4]:1 Arguments #self#::Core.Const(f) x::Int64 Locals @_3::Union{Float64, Int64} Body::Union{Float64, Int64} 1 ─ %1 = (x ≥ 0)::Bool └── goto #3 if not %1 2 ─ (@_3 = x) └── goto #4 3 ─ (@_3 = x + 0.0) 4 ┄ %6 = @_3::Union{Float64, Int64} │ %7 = Main.identity(%6)::Union{Float64, Int64} └── return %7 ```
markkitti 4y ago
Now with better formatting... This becomes an important part of optimizing Julia code. There is some tooling for this. Below, identity is a type stable function because we know that an Int64 argument results in a Int64 output. The macro code_warntype reveals the type analysis: julia> @code_warntype identity(5) MethodInstance for identity(::Int64) from identity(x) in Base at operators.jl:526 Arguments #self#::Core.Const(identity) x::Int64 Body::Int64 1 ─ return x julia> f(x) = identity(x ≥ 0 ? x : x + 0.0) f (generic function with 1 method) julia> @code_warntype f(5) MethodInstance for f(::Int64) from f(x) in Main at REPL[6]:1 Arguments #self#::Core.Const(f) x::Int64 Locals @_3::Union{Float64, Int64} Body::Union{Float64, Int64} 1 ─ %1 = (x ≥ 0)::Bool └── goto #3 if not %1 2 ─ (@_3 = x) └── goto #4 3 ─ (@_3 = x + 0.0) 4 ┄ %6 = @_3::Union{Float64, Int64} │ %7 = Main.identity(%6)::Union{Float64, Int64} └── return %7

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This becomes an important part of optimizing Julia code. There is some tooling for this. Below, identity is a type stable function because we know that an Int64 argument results in a Int64 output. The macro code_warntype reveals the type analysis: ``` julia> @code_warntype identity(5) MethodInstance for identity(::Int64) from identity(x) @ Base operators.jl:513 Arguments #self#::Core.Const(identity) x::Int64 Body::Int64 1 ─ nothing └── return x ``` This is type unstable and results in dynamic dispatch because we are not sure if the argument to identity will be an Int64 or a Float64. ``` julia> f(x) = identity(x ≥ 0 ? x : x + 0.0) f (generic function with 1 method) julia> @code_warntype f(5) MethodInstance for f(::Int64) from f(x) @ Main REPL[4]:1 Arguments #self#::Core.Const(f) x::Int64 Locals @_3::Union{Float64, Int64} Body::Union{Float64, Int64} 1 ─ %1 = (x ≥ 0)::Bool └── goto #3 if not %1 2 ─ (@_3 = x) └── goto #4 3 ─ (@_3 = x + 0.0) 4 ┄ %6 = @_3::Union{Float64, Int64} │ %7 = Main.identity(%6)::Union{Float64, Int64} └── return %7 ```

markkitti 4y ago

Now with better formatting... This becomes an important part of optimizing Julia code. There is some tooling for this. Below, identity is a type stable function because we know that an Int64 argument results in a Int64 output. The macro code_warntype reveals the type analysis: julia> @code_warntype identity(5) MethodInstance for identity(::Int64) from identity(x) in Base at operators.jl:526 Arguments #self#::Core.Const(identity) x::Int64 Body::Int64 1 ─ return x julia> f(x) = identity(x ≥ 0 ? x : x + 0.0) f (generic function with 1 method) julia> @code_warntype f(5) MethodInstance for f(::Int64) from f(x) in Main at REPL[6]:1 Arguments #self#::Core.Const(f) x::Int64 Locals @_3::Union{Float64, Int64} Body::Union{Float64, Int64} 1 ─ %1 = (x ≥ 0)::Bool └── goto #3 if not %1 2 ─ (@_3 = x) └── goto #4 3 ─ (@_3 = x + 0.0) 4 ┄ %6 = @_3::Union{Float64, Int64} │ %7 = Main.identity(%6)::Union{Float64, Int64} └── return %7