Confusing behavior of btime

General Usage
2

Sub-nanosecond (less than one clock cycle) results indicate that your benchmark has been compiled away (constant propagation is your “enemy” here). You can wrap the integer literal into a Ref to avoid constant propagation.

julia> f(x) = x^2
f (generic function with 1 method)

julia> @btime f(123456789);
  0.043 ns (0 allocations: 0 bytes)

julia> @btime f(Ref(123456789)[]);
  1.513 ns (0 allocations: 0 bytes)

julia> x = 123456789;

julia> @btime f($x);
  1.514 ns (0 allocations: 0 bytes)
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