/* memset/bzero with unaligned store and rep stosb

   Copyright (C) 2016-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

/* memset is implemented as:

   1. Use overlapping store to avoid branch.

   2. If size is less than VEC, use integer register stores.

   3. If size is from VEC_SIZE to 2 * VEC_SIZE, use 2 VEC stores.

   4. If size is from 2 * VEC_SIZE to 4 * VEC_SIZE, use 4 VEC stores.

   5. If size is more to 4 * VEC_SIZE, align to 4 * VEC_SIZE with

      4 VEC stores and store 4 * VEC at a time until done.  */

#include <sysdep.h>

#ifndef MEMSET_CHK_SYMBOL

# define MEMSET_CHK_SYMBOL(p,s)		MEMSET_SYMBOL(p, s)

#endif

#ifndef WMEMSET_CHK_SYMBOL

# define WMEMSET_CHK_SYMBOL(p,s)	WMEMSET_SYMBOL(p, s)

#endif

#ifndef VZEROUPPER

# if VEC_SIZE > 16

#  define VZEROUPPER			vzeroupper

# else

#  define VZEROUPPER

# endif

#endif

#ifndef VZEROUPPER_SHORT_RETURN

# if VEC_SIZE > 16

#  define VZEROUPPER_SHORT_RETURN	vzeroupper

# else

#  define VZEROUPPER_SHORT_RETURN	rep

# endif

#endif

#ifndef MOVQ

# if VEC_SIZE > 16

#  define MOVQ				vmovq

# else

#  define MOVQ				movq

# endif

#endif

/* Threshold to use Enhanced REP STOSB.  Since there is overhead to set

   up REP STOSB operation, REP STOSB isn't faster on short data.  The

   memset micro benchmark in glibc shows that 2KB is the approximate

   value above which REP STOSB becomes faster on processors with

   Enhanced REP STOSB.  Since the stored value is fixed, larger register

   size has minimal impact on threshold.  */

#ifndef REP_STOSB_THRESHOLD

# define REP_STOSB_THRESHOLD		2048

#endif

#ifndef SECTION

# error SECTION is not defined!

#endif

	.section SECTION(.text),"ax",@progbits

#if VEC_SIZE == 16 && IS_IN (libc)

ENTRY (__bzero)

	movq	%rdi, %rax /* Set return value.  */

	movq	%rsi, %rdx /* Set n.  */

	pxor	%xmm0, %xmm0

	jmp	L(entry_from_bzero)

END (__bzero)

weak_alias (__bzero, bzero)

#endif

#if IS_IN (libc)

# if defined SHARED

ENTRY_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))

	cmpq	%rdx, %rcx

	jb	HIDDEN_JUMPTARGET (__chk_fail)

END_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))

# endif

ENTRY (WMEMSET_SYMBOL (__wmemset, unaligned))

	shlq	$2, %rdx

	WMEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)

	jmp	L(entry_from_bzero)

END (WMEMSET_SYMBOL (__wmemset, unaligned))

#endif

#if defined SHARED && IS_IN (libc)

ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))

	cmpq	%rdx, %rcx

	jb	HIDDEN_JUMPTARGET (__chk_fail)

END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))

#endif

ENTRY (MEMSET_SYMBOL (__memset, unaligned))

	MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)

L(entry_from_bzero):

	cmpq	$VEC_SIZE, %rdx

	jb	L(less_vec)

	cmpq	$(VEC_SIZE * 2), %rdx

	ja	L(more_2x_vec)

	/* From VEC and to 2 * VEC.  No branch when size == VEC_SIZE.  */

	VMOVU	%VEC(0), -VEC_SIZE(%rdi,%rdx)

	VMOVU	%VEC(0), (%rdi)

	VZEROUPPER

	ret

#if defined USE_MULTIARCH && IS_IN (libc)

END (MEMSET_SYMBOL (__memset, unaligned))

# if VEC_SIZE == 16

ENTRY (__memset_chk_erms)

	cmpq	%rdx, %rcx

	jb	HIDDEN_JUMPTARGET (__chk_fail)

END (__memset_chk_erms)

/* Only used to measure performance of REP STOSB.  */

ENTRY (__memset_erms)

	/* Skip zero length.  */

	testq	%rdx, %rdx

	jnz	 L(stosb)

	movq	%rdi, %rax

	ret

# else

/* Provide a hidden symbol to debugger.  */

	.hidden	MEMSET_SYMBOL (__memset, erms)

ENTRY (MEMSET_SYMBOL (__memset, erms))

# endif

L(stosb):

	/* Issue vzeroupper before rep stosb.  */

	VZEROUPPER

	movq	%rdx, %rcx

	movzbl	%sil, %eax

	movq	%rdi, %rdx

	rep stosb

	movq	%rdx, %rax

	ret

# if VEC_SIZE == 16

END (__memset_erms)

# else

END (MEMSET_SYMBOL (__memset, erms))

# endif

# if defined SHARED && IS_IN (libc)

ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))

	cmpq	%rdx, %rcx

	jb	HIDDEN_JUMPTARGET (__chk_fail)

END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))

# endif

ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms))

	MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)

	cmpq	$VEC_SIZE, %rdx

	jb	L(less_vec)

	cmpq	$(VEC_SIZE * 2), %rdx

	ja	L(stosb_more_2x_vec)

	/* From VEC and to 2 * VEC.  No branch when size == VEC_SIZE.  */

	VMOVU	%VEC(0), -VEC_SIZE(%rdi,%rdx)

	VMOVU	%VEC(0), (%rdi)

	VZEROUPPER

	ret

L(stosb_more_2x_vec):

	cmpq	$REP_STOSB_THRESHOLD, %rdx

	ja	L(stosb)

#endif

L(more_2x_vec):

	cmpq  $(VEC_SIZE * 4), %rdx

	ja	L(loop_start)

	VMOVU	%VEC(0), (%rdi)

	VMOVU	%VEC(0), VEC_SIZE(%rdi)

	VMOVU	%VEC(0), -VEC_SIZE(%rdi,%rdx)

	VMOVU	%VEC(0), -(VEC_SIZE * 2)(%rdi,%rdx)

L(return):

	VZEROUPPER

	ret

L(loop_start):

	leaq	(VEC_SIZE * 4)(%rdi), %rcx

	VMOVU	%VEC(0), (%rdi)

	andq	$-(VEC_SIZE * 4), %rcx

	VMOVU	%VEC(0), -VEC_SIZE(%rdi,%rdx)

	VMOVU	%VEC(0), VEC_SIZE(%rdi)

	VMOVU	%VEC(0), -(VEC_SIZE * 2)(%rdi,%rdx)

	VMOVU	%VEC(0), (VEC_SIZE * 2)(%rdi)

	VMOVU	%VEC(0), -(VEC_SIZE * 3)(%rdi,%rdx)

	VMOVU	%VEC(0), (VEC_SIZE * 3)(%rdi)

	VMOVU	%VEC(0), -(VEC_SIZE * 4)(%rdi,%rdx)

	addq	%rdi, %rdx

	andq	$-(VEC_SIZE * 4), %rdx

	cmpq	%rdx, %rcx

	je	L(return)

L(loop):

	VMOVA	%VEC(0), (%rcx)

	VMOVA	%VEC(0), VEC_SIZE(%rcx)

	VMOVA	%VEC(0), (VEC_SIZE * 2)(%rcx)

	VMOVA	%VEC(0), (VEC_SIZE * 3)(%rcx)

	addq	$(VEC_SIZE * 4), %rcx

	cmpq	%rcx, %rdx

	jne	L(loop)

	VZEROUPPER_SHORT_RETURN

	ret

L(less_vec):

	/* Less than 1 VEC.  */

# if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64

#  error Unsupported VEC_SIZE!

# endif

# if VEC_SIZE > 32

	cmpb	$32, %dl

	jae	L(between_32_63)

# endif

# if VEC_SIZE > 16

	cmpb	$16, %dl

	jae	L(between_16_31)

# endif

	MOVQ	%xmm0, %rcx

	cmpb	$8, %dl

	jae	L(between_8_15)

	cmpb	$4, %dl

	jae	L(between_4_7)

	cmpb	$1, %dl

	ja	L(between_2_3)

	jb	1f

	movb	%cl, (%rdi)

1:

	VZEROUPPER

	ret

# if VEC_SIZE > 32

	/* From 32 to 63.  No branch when size == 32.  */

L(between_32_63):

	vmovdqu	%ymm0, -32(%rdi,%rdx)

	vmovdqu	%ymm0, (%rdi)

	VZEROUPPER

	ret

# endif

# if VEC_SIZE > 16

	/* From 16 to 31.  No branch when size == 16.  */

L(between_16_31):

	vmovdqu	%xmm0, -16(%rdi,%rdx)

	vmovdqu	%xmm0, (%rdi)

	VZEROUPPER

	ret

# endif

	/* From 8 to 15.  No branch when size == 8.  */

L(between_8_15):

	movq	%rcx, -8(%rdi,%rdx)

	movq	%rcx, (%rdi)

	VZEROUPPER

	ret

L(between_4_7):

	/* From 4 to 7.  No branch when size == 4.  */

	movl	%ecx, -4(%rdi,%rdx)

	movl	%ecx, (%rdi)

	VZEROUPPER

	ret

L(between_2_3):

	/* From 2 to 3.  No branch when size == 2.  */

	movw	%cx, -2(%rdi,%rdx)

	movw	%cx, (%rdi)

	VZEROUPPER

	ret

END (MEMSET_SYMBOL (__memset, unaligned_erms))