github.com/bir3/gocompiler@v0.9.2202/src/internal/bytealg/equal_arm.s (about)

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include "go_asm.h"
     6  #include "textflag.h"
     7  
     8  // memequal(a, b unsafe.Pointer, size uintptr) bool
     9  TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-13
    10  	MOVW	a+0(FP), R0
    11  	MOVW	b+4(FP), R2
    12  	CMP	R0, R2
    13  	B.EQ	eq
    14  	MOVW	size+8(FP), R1
    15  	CMP	$0, R1
    16  	B.EQ	eq		// short path to handle 0-byte case
    17  	MOVW	$ret+12(FP), R7
    18  	B	memeqbody<>(SB)
    19  eq:
    20  	MOVW	$1, R0
    21  	MOVB	R0, ret+12(FP)
    22  	RET
    23  
    24  // memequal_varlen(a, b unsafe.Pointer) bool
    25  TEXT runtime·memequal_varlen(SB),NOSPLIT|NOFRAME,$0-9
    26  	MOVW	a+0(FP), R0
    27  	MOVW	b+4(FP), R2
    28  	CMP	R0, R2
    29  	B.EQ	eq
    30  	MOVW	4(R7), R1	// compiler stores size at offset 4 in the closure
    31  	CMP	$0, R1
    32  	B.EQ	eq		// short path to handle 0-byte case
    33  	MOVW	$ret+8(FP), R7
    34  	B	memeqbody<>(SB)
    35  eq:
    36  	MOVW	$1, R0
    37  	MOVB	R0, ret+8(FP)
    38  	RET
    39  
    40  // Input:
    41  // R0: data of a
    42  // R1: length
    43  // R2: data of b
    44  // R7: points to return value
    45  //
    46  // On exit:
    47  // R4, R5 and R6 are clobbered
    48  TEXT memeqbody<>(SB),NOSPLIT|NOFRAME,$0-0
    49  	CMP	$1, R1
    50  	B.EQ	one		// 1-byte special case for better performance
    51  
    52  	CMP	$4, R1
    53  	ADD	R0, R1		// R1 is the end of the range to compare
    54  	B.LT	byte_loop	// length < 4
    55  	AND	$3, R0, R6
    56  	CMP	$0, R6
    57  	B.NE	byte_loop	// unaligned a, use byte-wise compare (TODO: try to align a)
    58  	AND	$3, R2, R6
    59  	CMP	$0, R6
    60  	B.NE	byte_loop	// unaligned b, use byte-wise compare
    61  	AND	$0xfffffffc, R1, R6
    62  	// length >= 4
    63  chunk4_loop:
    64  	MOVW.P	4(R0), R4
    65  	MOVW.P	4(R2), R5
    66  	CMP	R4, R5
    67  	B.NE	notequal
    68  	CMP	R0, R6
    69  	B.NE	chunk4_loop
    70  	CMP	R0, R1
    71  	B.EQ	equal		// reached the end
    72  byte_loop:
    73  	MOVBU.P	1(R0), R4
    74  	MOVBU.P	1(R2), R5
    75  	CMP	R4, R5
    76  	B.NE	notequal
    77  	CMP	R0, R1
    78  	B.NE	byte_loop
    79  equal:
    80  	MOVW	$1, R0
    81  	MOVB	R0, (R7)
    82  	RET
    83  one:
    84  	MOVBU	(R0), R4
    85  	MOVBU	(R2), R5
    86  	CMP	R4, R5
    87  	B.EQ	equal
    88  notequal:
    89  	MOVW	$0, R0
    90  	MOVB	R0, (R7)
    91  	RET