SIMD Support¶

Type VecElement{T} is intended for building libraries of SIMD operations. Practical use of it requires using llvmcall. The type is defined as:

immutableVecElement{T}value::Tend

It has a special compilation rule: a homogeneous tuple of VecElement{T} maps to an LLVM vector type when T is a bitstype and the tuple length is in the set {2-6,8-10,16}.

At -O3, the compiler might automatically vectorize operations on such tuples. For example, the following program, when compiled with julia-O3 generates two SIMD addition instructions (addps) on x86 systems:

typealias m128NTuple{4,VecElement{Float32}}function add(a::m128,b::m128)(VecElement(a[1].value+b[1].value),VecElement(a[2].value+b[2].value),VecElement(a[3].value+b[3].value),VecElement(a[4].value+b[4].value))endtriple(c::m128)=add(add(c,c),c)code_native(triple,(m128,))

However, since the automatic vectorization cannot be relied upon, future use will mostly be via libraries that use llvmcall.