asm_vecSqrt_sse.s

// +build sse
// +build amd64
// +build !fastmath

/*
Sqrt takes a []float32 and square roots every element in the slice.
*/
#include "textflag.h"

// func Sqrt(a []float32)
TEXT ·Sqrt(SB), NOSPLIT, $0
	MOVQ a_data+0(FP), SI
	MOVQ SI, CX
	MOVQ a_len+8(FP), AX  // len(a) into AX - +8, because first 8 is pointer, second 8 is length, third 8 is cap

	SUBQ $4, AX
	JL   remainder

loop:
	SQRTPS (SI), X0
	MOVUPS X0, (SI)

	// we processed 4 elements. Each element is 4 bytes. So jump 16 ahead
	ADDQ $16, SI

	SUBQ $4, AX
	JGE  loop

remainder:
	ADDQ $4, AX
	JE   done

remainder1:
	MOVSS  (SI), X0
	SQRTSS X0, X0
	MOVSS  X0, (SI)

	ADDQ $4, SI
	DECQ AX
	JNE  remainder1

done:
	RET