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glibc/sysdeps/arm/memmove.S

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/* Copyright (C) 2006-2024 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/>. */
/* Thumb requires excessive IT insns here. */
#define NO_THUMB
#include <sysdep.h>
#include <arm-features.h>
/*
* Data preload for architectures that support it (ARM V5TE and above)
*/
#if (!defined (__ARM_ARCH_2__) && !defined (__ARM_ARCH_3__) \
&& !defined (__ARM_ARCH_3M__) && !defined (__ARM_ARCH_4__) \
&& !defined (__ARM_ARCH_4T__) && !defined (__ARM_ARCH_5__) \
&& !defined (__ARM_ARCH_5T__))
#define PLD(code...) code
#else
#define PLD(code...)
#endif
/*
* This can be used to enable code to cacheline align the source pointer.
* Experiments on tested architectures (StrongARM and XScale) didn't show
* this a worthwhile thing to do. That might be different in the future.
*/
//#define CALGN(code...) code
#define CALGN(code...)
/*
* Endian independent macros for shifting bytes within registers.
*/
#ifndef __ARMEB__
#define PULL lsr
#define PUSH lsl
#else
#define PULL lsl
#define PUSH lsr
#endif
.text
.syntax unified
/*
* Prototype: void *memmove(void *dest, const void *src, size_t n);
*
* Note:
*
* If the memory regions don't overlap, we simply branch to memcpy which is
* normally a bit faster. Otherwise the copy is done going downwards.
*/
ENTRY(memmove)
subs ip, r0, r1
cmphi r2, ip
#if !IS_IN (libc)
bls memcpy
#else
bls HIDDEN_JUMPTARGET(memcpy)
#endif
push {r0, r4, lr}
cfi_adjust_cfa_offset (12)
cfi_rel_offset (r4, 4)
cfi_rel_offset (lr, 8)
cfi_remember_state
add r1, r1, r2
add r0, r0, r2
subs r2, r2, #4
blo 8f
ands ip, r0, #3
PLD( pld [r1, #-4] )
bne 9f
ands ip, r1, #3
bne 10f
1: subs r2, r2, #(28)
push {r5 - r8}
cfi_adjust_cfa_offset (16)
cfi_rel_offset (r5, 0)
cfi_rel_offset (r6, 4)
cfi_rel_offset (r7, 8)
cfi_rel_offset (r8, 12)
blo 5f
CALGN( ands ip, r1, #31 )
CALGN( sbcsne r4, ip, r2 ) @ C is always set here
CALGN( bcs 2f )
CALGN( adr r4, 6f )
CALGN( subs r2, r2, ip ) @ C is set here
#ifndef ARM_ALWAYS_BX
CALGN( add pc, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
#else
CALGN( add r4, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
CALGN( bx r4 )
#endif
PLD( pld [r1, #-4] )
2: PLD( cmp r2, #96 )
PLD( pld [r1, #-32] )
PLD( blo 4f )
PLD( pld [r1, #-64] )
PLD( pld [r1, #-96] )
3: PLD( pld [r1, #-128] )
4: ldmdb r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
subs r2, r2, #32
stmdb r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
bhs 3b
5: ands ip, r2, #28
rsb ip, ip, #32
#ifndef ARM_ALWAYS_BX
/* C is always clear here. */
addne pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
b 7f
#else
beq 7f
push {r10}
cfi_adjust_cfa_offset (4)
cfi_rel_offset (r10, 0)
0: add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
/* If alignment is not perfect, then there will be some
padding (nop) instructions between this BX and label 6.
The computation above assumed that two instructions
later is exactly the right spot. */
add r10, #(6f - (0b + PC_OFS))
bx r10
#endif
.p2align ARM_BX_ALIGN_LOG2
6: nop
.p2align ARM_BX_ALIGN_LOG2
ldr r3, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r4, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r5, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r6, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r7, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr r8, [r1, #-4]!
.p2align ARM_BX_ALIGN_LOG2
ldr lr, [r1, #-4]!
#ifndef ARM_ALWAYS_BX
add pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
nop
#else
0: add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
/* If alignment is not perfect, then there will be some
padding (nop) instructions between this BX and label 66.
The computation above assumed that two instructions
later is exactly the right spot. */
add r10, #(66f - (0b + PC_OFS))
bx r10
#endif
.p2align ARM_BX_ALIGN_LOG2
66: nop
.p2align ARM_BX_ALIGN_LOG2
str r3, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r4, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r5, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r6, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r7, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str r8, [r0, #-4]!
.p2align ARM_BX_ALIGN_LOG2
str lr, [r0, #-4]!
#ifdef ARM_ALWAYS_BX
pop {r10}
cfi_adjust_cfa_offset (-4)
cfi_restore (r10)
#endif
CALGN( bcs 2b )
7: pop {r5 - r8}
cfi_adjust_cfa_offset (-16)
cfi_restore (r5)
cfi_restore (r6)
cfi_restore (r7)
cfi_restore (r8)
8: movs r2, r2, lsl #31
ldrbne r3, [r1, #-1]!
ldrbcs r4, [r1, #-1]!
ldrbcs ip, [r1, #-1]
strbne r3, [r0, #-1]!
strbcs r4, [r0, #-1]!
strbcs ip, [r0, #-1]
#if ((defined (__ARM_ARCH_4T__) && defined (__THUMB_INTERWORK__)) \
|| defined (ARM_ALWAYS_BX))
pop {r0, r4, lr}
cfi_adjust_cfa_offset (-12)
cfi_restore (r4)
cfi_restore (lr)
bx lr
#else
pop {r0, r4, pc}
#endif
cfi_restore_state
9: cmp ip, #2
ldrbgt r3, [r1, #-1]!
ldrbge r4, [r1, #-1]!
ldrb lr, [r1, #-1]!
strbgt r3, [r0, #-1]!
strbge r4, [r0, #-1]!
subs r2, r2, ip
strb lr, [r0, #-1]!
blo 8b
ands ip, r1, #3
beq 1b
10: bic r1, r1, #3
cmp ip, #2
ldr r3, [r1, #0]
beq 17f
blt 18f
.macro backward_copy_shift push pull
subs r2, r2, #28
blo 14f
CALGN( ands ip, r1, #31 )
CALGN( rsb ip, ip, #32 )
CALGN( sbcsne r4, ip, r2 ) @ C is always set here
CALGN( subcc r2, r2, ip )
CALGN( bcc 15f )
11: push {r5 - r8, r10}
cfi_adjust_cfa_offset (20)
cfi_rel_offset (r5, 0)
cfi_rel_offset (r6, 4)
cfi_rel_offset (r7, 8)
cfi_rel_offset (r8, 12)
cfi_rel_offset (r10, 16)
PLD( pld [r1, #-4] )
PLD( cmp r2, #96 )
PLD( pld [r1, #-32] )
PLD( blo 13f )
PLD( pld [r1, #-64] )
PLD( pld [r1, #-96] )
12: PLD( pld [r1, #-128] )
13: ldmdb r1!, {r7, r8, r10, ip}
mov lr, r3, PUSH #\push
subs r2, r2, #32
ldmdb r1!, {r3, r4, r5, r6}
orr lr, lr, ip, PULL #\pull
mov ip, ip, PUSH #\push
orr ip, ip, r10, PULL #\pull
mov r10, r10, PUSH #\push
orr r10, r10, r8, PULL #\pull
mov r8, r8, PUSH #\push
orr r8, r8, r7, PULL #\pull
mov r7, r7, PUSH #\push
orr r7, r7, r6, PULL #\pull
mov r6, r6, PUSH #\push
orr r6, r6, r5, PULL #\pull
mov r5, r5, PUSH #\push
orr r5, r5, r4, PULL #\pull
mov r4, r4, PUSH #\push
orr r4, r4, r3, PULL #\pull
stmdb r0!, {r4 - r8, r10, ip, lr}
bhs 12b
pop {r5 - r8, r10}
cfi_adjust_cfa_offset (-20)
cfi_restore (r5)
cfi_restore (r6)
cfi_restore (r7)
cfi_restore (r8)
cfi_restore (r10)
14: ands ip, r2, #28
beq 16f
15: mov lr, r3, PUSH #\push
ldr r3, [r1, #-4]!
subs ip, ip, #4
orr lr, lr, r3, PULL #\pull
str lr, [r0, #-4]!
bgt 15b
CALGN( cmp r2, #0 )
CALGN( bge 11b )
16: add r1, r1, #(\pull / 8)
b 8b
.endm
backward_copy_shift push=8 pull=24
17: backward_copy_shift push=16 pull=16
18: backward_copy_shift push=24 pull=8
END(memmove)
libc_hidden_builtin_def (memmove)
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