glibc/sysdeps/powerpc/powerpc64/power7/memset.S

/* Optimized memset implementation for PowerPC64/POWER7.
   Copyright (C) 2010-2021 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
   <https://www.gnu.org/licenses/>.  */

#include <sysdep.h>

/* void * [r3] memset (void *s [r3], int c [r4], size_t n [r5]));
   Returns 's'.  */

#ifndef MEMSET
# define MEMSET memset
#endif
	.machine power7
ENTRY_TOCLESS (MEMSET, 5)
	CALL_MCOUNT 3

L(_memset):
	cmpldi	cr7,5,31
	cmpldi	cr6,5,8
	mr	10,3

	/* Replicate byte to word.  */
	insrdi	4,4,8,48
	insrdi	4,4,16,32
	ble	cr6,L(small)	/* If length <= 8, use short copy code.  */

	neg	0,3
	ble	cr7,L(medium)	/* If length < 32, use medium copy code.  */

	andi.	11,10,7		/* Check alignment of SRC.  */
	insrdi	4,4,32,0	/* Replicate word to double word.  */

	mr	12,5
	beq	L(big_aligned)

	clrldi	0,0,61
	mtocrf	0x01,0
	subf	5,0,5

	/* Get DST aligned to 8 bytes.  */
1:	bf	31,2f

	stb	4,0(10)
	addi	10,10,1
2:	bf	30,4f

	sth	4,0(10)
	addi	10,10,2
4:	bf	29,L(big_aligned)

	stw	4,0(10)
	addi	10,10,4

	.align	4
L(big_aligned):

	cmpldi	cr5,5,255
	li	0,32
	dcbtst	0,10
	cmpldi	cr6,4,0
	srdi	9,5,3	/* Number of full doublewords remaining.  */
	crand	27,26,21
	mtocrf	0x01,9
	bt	27,L(huge)

	/* From this point on, we'll copy 32+ bytes and the value
	   isn't 0 (so we can't use dcbz).  */

	srdi	8,5,5
	clrldi	11,5,61
	cmpldi	cr6,11,0
	cmpldi	cr1,9,4
	mtctr	8

	/* Copy 1~3 doublewords so the main loop starts
	at a multiple of 32 bytes.  */

	bf	30,1f

	std	4,0(10)
	std	4,8(10)
	addi	10,10,16
	bf	31,L(big_loop)

	std	4,0(10)
	addi	10,10,8
	mr	12,10
	blt	cr1,L(tail_bytes)
	b	L(big_loop)

	.align	4
1:	/* Copy 1 doubleword.  */
	bf	31,L(big_loop)

	std	4,0(10)
	addi	10,10,8

	/* Main aligned copy loop.  Copies 32-bytes at a time and
	   ping-pong through r10 and r12 to avoid AGEN delays.  */
	.align	4
L(big_loop):
	addi	12,10,32
	std	4,0(10)
	std	4,8(10)
	std	4,16(10)
	std	4,24(10)
	bdz	L(tail_bytes)

	addi	10,10,64
	std	4,0(12)
	std	4,8(12)
	std	4,16(12)
	std	4,24(12)
	bdnz	L(big_loop)

	mr	12,10
	b	L(tail_bytes)

	.align	4
L(tail_bytes):

	/* Check for tail bytes.  */
	beqlr	cr6

	clrldi	0,5,61
	mtocrf	0x01,0

	/*  At this point we have a tail of 0-7 bytes and we know that the
	destination is doubleword-aligned.  */
4:	/* Copy 4 bytes.  */
	bf	29,2f

	stw	4,0(12)
	addi	12,12,4
2:	/* Copy 2 bytes.  */
	bf	30,1f

	sth	4,0(12)
	addi	12,12,2
1:	/* Copy 1 byte.  */
	bflr	31

	stb	4,0(12)
	blr

	/* Special case when value is 0 and we have a long length to deal
	   with.  Use dcbz to zero out 128-bytes at a time.  Before using
	   dcbz though, we need to get the destination 128-bytes aligned.  */
	.align	4
L(huge):
	andi.	11,10,127
	neg	0,10
	beq	L(huge_aligned)

	clrldi	0,0,57
	subf	5,0,5
	srdi	0,0,3
	mtocrf	0x01,0

	/* Get DST aligned to 128 bytes.  */
8:	bf	28,4f

	std	4,0(10)
	std	4,8(10)
	std	4,16(10)
	std	4,24(10)
	std	4,32(10)
	std	4,40(10)
	std	4,48(10)
	std	4,56(10)
	addi	10,10,64
	.align	4
4:	bf	29,2f

	std	4,0(10)
	std	4,8(10)
	std	4,16(10)
	std	4,24(10)
	addi	10,10,32
	.align	4
2:	bf	30,1f

	std	4,0(10)
	std	4,8(10)
	addi	10,10,16
	.align	4
1:	bf	31,L(huge_aligned)

	std	4,0(10)
	addi	10,10,8


L(huge_aligned):
	srdi	8,5,7
	clrldi	11,5,57
	cmpldi	cr6,11,0
	mtctr	8

	.align	4
L(huge_loop):
	dcbz	0,10
	addi	10,10,128
	bdnz	L(huge_loop)

	/* Check how many bytes are still left.  */
	beqlr	cr6

	subf	9,3,10
	subf	5,9,12
	srdi	8,5,3
	cmpldi	cr6,8,0
	mtocrf	0x01,8

	/* We have a tail o 1~127 bytes.  Copy up to 15 doublewords for
	speed.  We'll handle the resulting tail bytes later.  */
	beq	cr6,L(tail)

8:	bf	28,4f

	std	4,0(10)
	std	4,8(10)
	std	4,16(10)
	std	4,24(10)
	std	4,32(10)
	std	4,40(10)
	std	4,48(10)
	std	4,56(10)
	addi	10,10,64
	.align	4
4:	bf	29,2f

	std	4,0(10)
	std	4,8(10)
	std	4,16(10)
	std	4,24(10)
	addi	10,10,32
	.align	4
2:	bf	30,1f

	std	4,0(10)
	std	4,8(10)
	addi	10,10,16
	.align	4
1:	bf	31,L(tail)

	std	4,0(10)
	addi	10,10,8

	/* Handle the rest of the tail bytes here.  */
L(tail):
	mtocrf	0x01,5

	.align	4
4:	bf	29,2f

	stw	4,0(10)
	addi	10,10,4
	.align	4
2:	bf	30,1f

	sth	4,0(10)
	addi	10,10,2
	.align	4
1:	bflr	31

	stb	4,0(10)
	blr

	/* Expanded tree to copy tail bytes without increments.  */
	.align	4
L(copy_tail):
	bf	29,L(FXX)

	stw	4,0(10)
	bf	30,L(TFX)

	sth	4,4(10)
	bflr	31

	stb	4,6(10)
	blr

	.align	4
L(FXX):	bf	30,L(FFX)

	sth	4,0(10)
	bflr	31

	stb	4,2(10)
	blr

	.align	4
L(TFX):	bflr	31

	stb	4,4(10)
	blr

	.align	4
L(FFX):	bflr	31

	stb	4,0(10)
	blr

	/* Handle copies of 9~31 bytes.  */
	.align	4
L(medium):
	/* At least 9 bytes to go.  */
	andi.	11,10,3
	clrldi	0,0,62
	beq	L(medium_aligned)

	/* Force 4-bytes alignment for DST.  */
	mtocrf	0x01,0
	subf	5,0,5
1:	/* Copy 1 byte.  */
	bf	31,2f

	stb	4,0(10)
	addi	10,10,1
2:	/* Copy 2 bytes.  */
	bf	30,L(medium_aligned)

	sth	4,0(10)
	addi	10,10,2

	.align	4
L(medium_aligned):
	/* At least 6 bytes to go, and DST is word-aligned.  */
	cmpldi	cr1,5,16
	mtocrf	0x01,5
	blt	cr1,8f

	/* Copy 16 bytes.  */
	stw	4,0(10)
	stw	4,4(10)
	stw	4,8(10)
	stw	4,12(10)
	addi	10,10,16
8:	/* Copy 8 bytes.  */
	bf	28,4f

	stw	4,0(10)
	stw	4,4(10)
	addi	10,10,8
4:	/* Copy 4 bytes.  */
	bf	29,2f

	stw	4,0(10)
	addi	10,10,4
2:	/* Copy 2-3 bytes.  */
	bf	30,1f

	sth	4,0(10)
	addi	10,10,2
1:	/* Copy 1 byte.  */
	bflr	31

	stb	4,0(10)
	blr

	/* Handles copies of 0~8 bytes.  */
	.align	4
L(small):
	mtocrf	0x01,5
	bne	cr6,L(copy_tail)

	stw	4,0(10)
	stw	4,4(10)
	blr

END_GEN_TB (MEMSET,TB_TOCLESS)
libc_hidden_builtin_def (memset)

/* Copied from bzero.S to prevent the linker from inserting a stub
   between bzero and memset.  */
ENTRY_TOCLESS (__bzero)
	CALL_MCOUNT 3
	mr	r5,r4
	li	r4,0
	b	L(_memset)
END (__bzero)
#ifndef __bzero
weak_alias (__bzero, bzero)
#endif