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// Copyright ©2017 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !noasm,!gccgo,!safe
#include "textflag.h"
#define HADDPD_SUM_SUM LONG $0xC07C0F66 // @ HADDPD X0, X0
#define X_PTR SI
#define Y_PTR DI
#define LEN CX
#define TAIL BX
#define IDX AX
#define SUM X0
#define P_SUM X1
// func DdotUnitary(x, y []float32) (sum float32)
TEXT ·DdotUnitary(SB), NOSPLIT, $0
MOVQ x_base+0(FP), X_PTR // X_PTR = &x
MOVQ y_base+24(FP), Y_PTR // Y_PTR = &y
MOVQ x_len+8(FP), LEN // LEN = min( len(x), len(y) )
CMPQ y_len+32(FP), LEN
CMOVQLE y_len+32(FP), LEN
PXOR SUM, SUM // psum = 0
CMPQ LEN, $0
JE dot_end
XORQ IDX, IDX
MOVQ Y_PTR, DX
ANDQ $0xF, DX // Align on 16-byte boundary for ADDPS
JZ dot_no_trim // if DX == 0 { goto dot_no_trim }
SUBQ $16, DX
dot_align: // Trim first value(s) in unaligned buffer do {
CVTSS2SD (X_PTR)(IDX*4), X2 // X2 = float64(x[i])
CVTSS2SD (Y_PTR)(IDX*4), X3 // X3 = float64(y[i])
MULSD X3, X2
ADDSD X2, SUM // SUM += X2
INCQ IDX // IDX++
DECQ LEN
JZ dot_end // if --TAIL == 0 { return }
ADDQ $4, DX
JNZ dot_align // } while --LEN > 0
dot_no_trim:
PXOR P_SUM, P_SUM // P_SUM = 0 for pipelining
MOVQ LEN, TAIL
ANDQ $0x7, TAIL // TAIL = LEN % 8
SHRQ $3, LEN // LEN = floor( LEN / 8 )
JZ dot_tail_start // if LEN == 0 { goto dot_tail_start }
dot_loop: // Loop unrolled 8x do {
CVTPS2PD (X_PTR)(IDX*4), X2 // X_i = x[i:i+1]
CVTPS2PD 8(X_PTR)(IDX*4), X3
CVTPS2PD 16(X_PTR)(IDX*4), X4
CVTPS2PD 24(X_PTR)(IDX*4), X5
CVTPS2PD (Y_PTR)(IDX*4), X6 // X_j = y[i:i+1]
CVTPS2PD 8(Y_PTR)(IDX*4), X7
CVTPS2PD 16(Y_PTR)(IDX*4), X8
CVTPS2PD 24(Y_PTR)(IDX*4), X9
MULPD X6, X2 // X_i *= X_j
MULPD X7, X3
MULPD X8, X4
MULPD X9, X5
ADDPD X2, SUM // SUM += X_i
ADDPD X3, P_SUM
ADDPD X4, SUM
ADDPD X5, P_SUM
ADDQ $8, IDX // IDX += 8
DECQ LEN
JNZ dot_loop // } while --LEN > 0
ADDPD P_SUM, SUM // SUM += P_SUM
CMPQ TAIL, $0 // if TAIL == 0 { return }
JE dot_end
dot_tail_start:
MOVQ TAIL, LEN
SHRQ $1, LEN
JZ dot_tail_one
dot_tail_two:
CVTPS2PD (X_PTR)(IDX*4), X2 // X_i = x[i:i+1]
CVTPS2PD (Y_PTR)(IDX*4), X6 // X_j = y[i:i+1]
MULPD X6, X2 // X_i *= X_j
ADDPD X2, SUM // SUM += X_i
ADDQ $2, IDX // IDX += 2
DECQ LEN
JNZ dot_tail_two // } while --LEN > 0
ANDQ $1, TAIL
JZ dot_end
dot_tail_one:
CVTSS2SD (X_PTR)(IDX*4), X2 // X2 = float64(x[i])
CVTSS2SD (Y_PTR)(IDX*4), X3 // X3 = float64(y[i])
MULSD X3, X2 // X2 *= X3
ADDSD X2, SUM // SUM += X2
dot_end:
HADDPD_SUM_SUM // SUM = \sum{ SUM[i] }
MOVSD SUM, sum+48(FP) // return SUM
RET