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// Copyright 2014 The Go 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 !plan9
#include "textflag.h"
// NOTE: Windows externalthreadhandler expects memclr to preserve DX.
// void runtime·memclr(void*, uintptr)
TEXT runtime·memclr(SB), NOSPLIT, $0-16
MOVQ ptr+0(FP), DI
MOVQ n+8(FP), BX
XORQ AX, AX
// MOVOU seems always faster than REP STOSQ.
clr_tail:
TESTQ BX, BX
JEQ clr_0
CMPQ BX, $2
JBE clr_1or2
CMPQ BX, $4
JBE clr_3or4
CMPQ BX, $8
JBE clr_5through8
CMPQ BX, $16
JBE clr_9through16
PXOR X0, X0
CMPQ BX, $32
JBE clr_17through32
CMPQ BX, $64
JBE clr_33through64
CMPQ BX, $128
JBE clr_65through128
CMPQ BX, $256
JBE clr_129through256
// TODO: use branch table and BSR to make this just a single dispatch
// TODO: for really big clears, use MOVNTDQ.
clr_loop:
MOVOU X0, 0(DI)
MOVOU X0, 16(DI)
MOVOU X0, 32(DI)
MOVOU X0, 48(DI)
MOVOU X0, 64(DI)
MOVOU X0, 80(DI)
MOVOU X0, 96(DI)
MOVOU X0, 112(DI)
MOVOU X0, 128(DI)
MOVOU X0, 144(DI)
MOVOU X0, 160(DI)
MOVOU X0, 176(DI)
MOVOU X0, 192(DI)
MOVOU X0, 208(DI)
MOVOU X0, 224(DI)
MOVOU X0, 240(DI)
SUBQ $256, BX
ADDQ $256, DI
CMPQ BX, $256
JAE clr_loop
JMP clr_tail
clr_1or2:
MOVB AX, (DI)
MOVB AX, -1(DI)(BX*1)
RET
clr_0:
RET
clr_3or4:
MOVW AX, (DI)
MOVW AX, -2(DI)(BX*1)
RET
clr_5through8:
MOVL AX, (DI)
MOVL AX, -4(DI)(BX*1)
RET
clr_9through16:
MOVQ AX, (DI)
MOVQ AX, -8(DI)(BX*1)
RET
clr_17through32:
MOVOU X0, (DI)
MOVOU X0, -16(DI)(BX*1)
RET
clr_33through64:
MOVOU X0, (DI)
MOVOU X0, 16(DI)
MOVOU X0, -32(DI)(BX*1)
MOVOU X0, -16(DI)(BX*1)
RET
clr_65through128:
MOVOU X0, (DI)
MOVOU X0, 16(DI)
MOVOU X0, 32(DI)
MOVOU X0, 48(DI)
MOVOU X0, -64(DI)(BX*1)
MOVOU X0, -48(DI)(BX*1)
MOVOU X0, -32(DI)(BX*1)
MOVOU X0, -16(DI)(BX*1)
RET
clr_129through256:
MOVOU X0, (DI)
MOVOU X0, 16(DI)
MOVOU X0, 32(DI)
MOVOU X0, 48(DI)
MOVOU X0, 64(DI)
MOVOU X0, 80(DI)
MOVOU X0, 96(DI)
MOVOU X0, 112(DI)
MOVOU X0, -128(DI)(BX*1)
MOVOU X0, -112(DI)(BX*1)
MOVOU X0, -96(DI)(BX*1)
MOVOU X0, -80(DI)(BX*1)
MOVOU X0, -64(DI)(BX*1)
MOVOU X0, -48(DI)(BX*1)
MOVOU X0, -32(DI)(BX*1)
MOVOU X0, -16(DI)(BX*1)
RET
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