Golang assembly implement of _mm_add_epi32

问题

I'm trying to implement _mm_add_epi32 in golang assembly, optionally with help of avo. But I know little about assembly and do not even know how to start it. Can you give me some hint of code? Thank you all.

Here's the equivalent slower golang version:

func add(x, y []uint32) []uint32 {
    if len(x) != len(y) {
        return nil
    }

    result := make([]uint32, len(x))
    for i := 0; i < len(x); i++ {
        result[i] = x[i] + y[i]
    }
    return result
}

I know that the struction paddq xmm, xmm is what we need, but do not kown how to convert a slice of []byte to the 256 bit register YMM.

回答1:

Here's an example for such an addition function:

    // func add(x, y [8]int32) [8]int32
    // q = x + y
TEXT ·add(SB),0,$0
    VMOVDQU x+0(FP), Y0
    VPADDD  Y+32(FP), Y0, Y0
    VMOVDQU Y0, q+64(FP)
    VZEROUPPER
    RET

Before reading this code, familiarise yourself with this document. Unfortunately, Go-style assembly (aka Plan 9-style assembly) is poorly documented.

Arrays are passed on the stack by value. A return value is passed as an extra rightmost argument read back by the caller. Use (FP) as documented in the document I linked to access function arguments.

Apart from that, it's pretty straightforward. The syntax is similar (but not equal) to AT&T syntax. Note that the register names are different and giving a size suffix is mandatory.

As you can see, writing an assembly function for a single operation is pretty pointless. It's probably going to work a lot better to take the algorithm you need and write it completely in assembly.

来源：https://stackoverflow.com/questions/63242918/golang-assembly-implement-of-mm-add-epi32