Using CLMUL instruction

General Usage
9

I don’t have much experience with this, so I was wondering: why is the last argument an Int32? Looking at PCLMULQDQ — Carry-Less Multiplication Quadword, I would have expected a 8 bytes, and that does seem to work as well:

const m128 = NTuple{2,VecElement{Int64}}

function carrylessmul(a::m128, b::m128)
    ccall("llvm.x86.pclmulqdq", llvmcall, m128, (m128, m128, UInt8), a, b, 0)
end

julia> @code_native carrylessmul(m128((1, 2)), m128((3, 4)))
	.section	__TEXT,__text,regular,pure_instructions
; ┌ @ REPL[8]:2 within `carrylessmul'
	vpclmulqdq	$0, %xmm1, %xmm0, %xmm0
	retl
	nopw	(%eax,%eax)
; └
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