// Copyright 2018 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.
#include "go_asm.h"
#include "textflag.h"
// memequal_varlen(a, b unsafe.Pointer) bool
TEXT runtime·memequal_varlen<ABIInternal>(SB),NOSPLIT,$0-17
MOVD 8(R26), R2 // compiler stores size at offset 8 in the closure
CBZ R2, eq
B runtime·memequal<ABIInternal>(SB)
eq:
MOVD $1, R0
RET
// input:
// R0: pointer a
// R1: pointer b
// R2: data len
// at return: result in R0
// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-25
// short path to handle 0-byte case
CBZ R2, equal
// short path to handle equal pointers
CMP R0, R1
BEQ equal
CMP $1, R2
// handle 1-byte special case for better performance
BEQ one
CMP $16, R2
// handle specially if length < 16
BLO tail
BIC $0x3f, R2, R3
CBZ R3, chunk16
// work with 64-byte chunks
ADD R3, R0, R6 // end of chunks
chunk64_loop:
VLD1.P (R0), [V0.D2, V1.D2, V2.D2, V3.D2]
VLD1.P (R1), [V4.D2, V5.D2, V6.D2, V7.D2]
VCMEQ V0.D2, V4.D2, V8.D2
VCMEQ V1.D2, V5.D2, V9.D2
VCMEQ V2.D2, V6.D2, V10.D2
VCMEQ V3.D2, V7.D2, V11.D2
VAND V8.B16, V9.B16, V8.B16
VAND V8.B16, V10.B16, V8.B16
VAND V8.B16, V11.B16, V8.B16
CMP R0, R6
VMOV V8.D[0], R4
VMOV V8.D[1], R5
CBZ R4, not_equal
CBZ R5, not_equal
BNE chunk64_loop
AND $0x3f, R2, R2
CBZ R2, equal
chunk16:
// work with 16-byte chunks
BIC $0xf, R2, R3
CBZ R3, tail
ADD R3, R0, R6 // end of chunks
chunk16_loop:
LDP.P 16(R0), (R4, R5)
LDP.P 16(R1), (R7, R9)
EOR R4, R7
CBNZ R7, not_equal
EOR R5, R9
CBNZ R9, not_equal
CMP R0, R6
BNE chunk16_loop
AND $0xf, R2, R2
CBZ R2, equal
tail:
// special compare of tail with length < 16
TBZ $3, R2, lt_8
MOVD (R0), R4
MOVD (R1), R5
EOR R4, R5
CBNZ R5, not_equal
SUB $8, R2, R6 // offset of the last 8 bytes
MOVD (R0)(R6), R4
MOVD (R1)(R6), R5
EOR R4, R5
CBNZ R5, not_equal
B equal
PCALIGN $16
lt_8:
TBZ $2, R2, lt_4
MOVWU (R0), R4
MOVWU (R1), R5
EOR R4, R5
CBNZ R5, not_equal
SUB $4, R2, R6 // offset of the last 4 bytes
MOVWU (R0)(R6), R4
MOVWU (R1)(R6), R5
EOR R4, R5
CBNZ R5, not_equal
B equal
PCALIGN $16
lt_4:
TBZ $1, R2, lt_2
MOVHU.P 2(R0), R4
MOVHU.P 2(R1), R5
CMP R4, R5
BNE not_equal
lt_2:
TBZ $0, R2, equal
one:
MOVBU (R0), R4
MOVBU (R1), R5
CMP R4, R5
BNE not_equal
equal:
MOVD $1, R0
RET
not_equal:
MOVB ZR, R0
RET
