benchmark different abs versions

benchmark.jl

function checked_abs{T<:Signed}(x::T)
    x == typemin(T) && throw(OverflowError())
    abs(x)
end
function scott_abs{T<:Signed}(x::T)
    (v = abs(x)) < 0 && throw(OverflowError())
    v
end
function testnoop(n)
    local v::Int
    local i::Int
    for i = -n:n
        v = i
    end
    v
end
function testabs(n)
    local v::Int
    local i::Int
    for i = -n:n
        v = abs(i)
    end
    v
end
function testca(n)
    local v::Int
    local i::Int
    for i = -n:n
        v = checked_abs(i)
    end
    v
end
function testsa(n)
    local v::Int
    local i::Int
    for i = -n:n
        v = scott_abs(i)
    end
    v
end
# make sure they get compiled
@time testnoop(1)
@time testabs(1)
@time testca(1)
@time testsa(1)
# Run for real
println("v = i")
gc() ; gc() ; @time testnoop(1000000)
println("v = abs(i)")
gc() ; gc() ; @time testabs(1000000)
println("v = scott_abs(i)")
gc() ; gc() ; @time testsa(1000000)
println("v = checked_abs(i)")
gc() ; gc() ; @time testca(1000000)

# Show actual generated code
if false
    @code_native(abs(-1))
    @code_native(checked_abs(-1))
    @code_native(scott_abs(-1))
end

# Where are these macros defined?
#Pkg.add("Benchmark")
#using Benchmarks
#@benchmark abs(-1)
#@benchmark checked_abs(-1)
#@benchmark scott_abs(-1)