simdloop.jl

function simd_loop_example_from_manual(x, y, z)
    s = zero(eltype(z))
    n = min(length(x),length(y),length(z))
    @simd for i in 1:n
        @inbounds begin
            z[i] = x[i]-y[i]
            s += z[i]*z[i]
        end
    end
    s
end

function simd_loop_with_multiple_reductions(x, y, z)
    # Use non-zero initial value to make sure reduction values include it.
    (s,t) = (one(eltype(x)),one(eltype(y)))
    @simd for i in 1:length(z)
        @inbounds begin
            s += x[i]
            t += 2*y[i]
            s += z[i]   # Two reductions go into s
        end
    end
    (s,t)
end

for T in {Int32,Int64,Float32,Float64}
   # Try various lengths to make sure "remainder loop" works
   for n in {0,1,2,3,4,255,256,257}
        # Dataset chosen so that results will be exact with only 24 bits of mantissa
        a = convert(Array{T},[2*j+1 for j in 1:n])
        b = convert(Array{T},[3*j+2 for j in 1:n])
        c = convert(Array{T},[5*j+3 for j in 1:n])
        s = simd_loop_example_from_manual(a,b,c)

        @test a==[2*j+1 for j in 1:n]
        @test b==[3*j+2 for j in 1:n]
        @test c==[-j-1 for j in 1:n]
        @test s==sum(c.*c)
        (s,t) = simd_loop_with_multiple_reductions(a,b,c)
        @test s==sum(a)+sum(c)+1
        @test t==2*sum(b)+1
    end
end

# Test that scope rules match regular for
let j=4
    # Use existing local variable.
    @simd for j=1:0 end
    @test j==4
    @simd for j=1:3 end
    @test j==3

    # Use global variable
    global simd_glob = 4
    @simd for simd_glob=1:0 end
    @test simd_glob==4
    @simd for simd_glob=1:3 end
    @test simd_glob==3

    # Index that is local to loop
    @simd for simd_loop_local=1:0 end
    simd_loop_local_present = true
    try 
        simd_loop_local += 1
    catch
        simd_loop_local_present = false
    end
    @test !simd_loop_local_present
end