Results from https://github.com/JuliaLang/julia/pull/6271 on 2014-Nov-25 17:13 CST.

gistfile1.txt

$ cat toivoh.jl
module TestSLP

function rmw!{T}(dest::Ptr{T}, src::Ptr{T})
    s1 = unsafe_load(src, 1)
    s2 = unsafe_load(src, 2)
    d1 = unsafe_load(dest, 1)
    d2 = unsafe_load(dest, 2)
    d1 $= s1
    d2 $= s2
    unsafe_store!(dest, d1, 1)
    unsafe_store!(dest, d2, 2)
    nothing
end

function rmw2!{T}(dest::Vector{T}, src::Vector{T})
    psrc, pdest = pointer(src), pointer(dest)
    s1 = unsafe_load(psrc, 1)
    s2 = unsafe_load(psrc, 2)
    d1 = unsafe_load(pdest, 1)
    d2 = unsafe_load(pdest, 2)
    d1 $= s1
    d2 $= s2
    unsafe_store!(pdest, d1, 1)
    unsafe_store!(pdest, d2, 2)
    nothing
end

function rmw2b!{T}(dest::Vector{T}, src::Vector{T})
    @inbounds s1 = src[1]
    @inbounds s2 = src[2]
    @inbounds d1 = dest[1]
    @inbounds d2 = dest[2]
    d1 $= s1
    d2 $= s2
    pdest = pointer(dest)
    unsafe_store!(pdest, d1, 1)
    unsafe_store!(pdest, d2, 2)
    nothing
end

function rmw3!{T}(dest::Vector{T}, src::Vector{T})
    @inbounds s1 = src[1]
    @inbounds s2 = src[2]
    @inbounds d1 = dest[1]
    @inbounds d2 = dest[2]
    d1 $= s1
    d2 $= s2
    @inbounds dest[1] = d1
    @inbounds dest[2] = d2
    nothing
end

println("\n\nrmw!: ")
code_native(rmw!, (Ptr{Uint64}, Ptr{Uint64}))

println("\n\nrmw2!: ")
code_native(rmw2!, (Vector{Uint64}, Vector{Uint64}))

println("\n\nrmw2b!: ")
code_native(rmw2b!, (Vector{Uint64}, Vector{Uint64}))

println("\n\nrmw3!: ")
code_native(rmw3!, (Vector{Uint64}, Vector{Uint64}))

end # module
$ julia -O toivoh.jl


rmw!:
        .text
Filename: toivoh.jl
Source line: 0
        push    rbp
        mov     rbp, rsp
Source line: 6
        vmovups xmm0, xmmword ptr [rdi]
Source line: 8
        vxorps  xmm0, xmm0, xmmword ptr [rsi]
Source line: 10
        vmovups xmmword ptr [rdi], xmm0
Source line: 12
        pop     rbp
        ret


rmw2!:
        .text
Filename: toivoh.jl
Source line: 0
        push    rbp
        mov     rbp, rsp
Source line: 16
        mov     rax, qword ptr [rsi + 8]
        mov     rcx, qword ptr [rdi + 8]
Source line: 19
        vmovups xmm0, xmmword ptr [rcx]
Source line: 21
        vxorps  xmm0, xmm0, xmmword ptr [rax]
Source line: 23
        vmovups xmmword ptr [rcx], xmm0
Source line: 25
        pop     rbp
        ret


rmw2b!:
        .text
Filename: toivoh.jl
Source line: 0
        push    rbp
        mov     rbp, rsp
Source line: 29
        mov     rax, qword ptr [rsi + 8]
Source line: 31
        mov     rcx, qword ptr [rdi + 8]
        vmovups xmm0, xmmword ptr [rcx]
Source line: 33
        vxorps  xmm0, xmm0, xmmword ptr [rax]
Source line: 36
        vmovups xmmword ptr [rcx], xmm0
Source line: 38
        pop     rbp
        ret


rmw3!:
        .text
Filename: toivoh.jl
Source line: 0
        push    rbp
        mov     rbp, rsp
Source line: 42
        mov     rax, qword ptr [rsi + 8]
Source line: 44
        mov     rcx, qword ptr [rdi + 8]
        vmovups xmm0, xmmword ptr [rcx]
Source line: 46
        vxorps  xmm0, xmm0, xmmword ptr [rax]
Source line: 48
        vmovups xmmword ptr [rcx], xmm0
Source line: 50
        pop     rbp
        ret
$