aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/go/_std_1.18/src/internal/bytealg/indexbyte_amd64.s
blob: f78093c539013e15af1813daf2256f3f19bc7d6a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
// 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"

TEXT	·IndexByte(SB), NOSPLIT, $0-40
	MOVQ b_base+0(FP), SI
	MOVQ b_len+8(FP), BX
	MOVB c+24(FP), AL
	LEAQ ret+32(FP), R8
	JMP  indexbytebody<>(SB)

TEXT	·IndexByteString(SB), NOSPLIT, $0-32
	MOVQ s_base+0(FP), SI
	MOVQ s_len+8(FP), BX
	MOVB c+16(FP), AL
	LEAQ ret+24(FP), R8
	JMP  indexbytebody<>(SB)

// input:
//   SI: data
//   BX: data len
//   AL: byte sought
//   R8: address to put result
TEXT	indexbytebody<>(SB), NOSPLIT, $0
	// Shuffle X0 around so that each byte contains
	// the character we're looking for.
	MOVD AX, X0
	PUNPCKLBW X0, X0
	PUNPCKLBW X0, X0
	PSHUFL $0, X0, X0

	CMPQ BX, $16
	JLT small

	MOVQ SI, DI

	CMPQ BX, $32
	JA avx2
sse:
	LEAQ	-16(SI)(BX*1), AX	// AX = address of last 16 bytes
	JMP	sseloopentry

sseloop:
	// Move the next 16-byte chunk of the data into X1.
	MOVOU	(DI), X1
	// Compare bytes in X0 to X1.
	PCMPEQB	X0, X1
	// Take the top bit of each byte in X1 and put the result in DX.
	PMOVMSKB X1, DX
	// Find first set bit, if any.
	BSFL	DX, DX
	JNZ	ssesuccess
	// Advance to next block.
	ADDQ	$16, DI
sseloopentry:
	CMPQ	DI, AX
	JB	sseloop

	// Search the last 16-byte chunk. This chunk may overlap with the
	// chunks we've already searched, but that's ok.
	MOVQ	AX, DI
	MOVOU	(AX), X1
	PCMPEQB	X0, X1
	PMOVMSKB X1, DX
	BSFL	DX, DX
	JNZ	ssesuccess

failure:
	MOVQ $-1, (R8)
	RET

// We've found a chunk containing the byte.
// The chunk was loaded from DI.
// The index of the matching byte in the chunk is DX.
// The start of the data is SI.
ssesuccess:
	SUBQ SI, DI	// Compute offset of chunk within data.
	ADDQ DX, DI	// Add offset of byte within chunk.
	MOVQ DI, (R8)
	RET

// handle for lengths < 16
small:
	TESTQ	BX, BX
	JEQ	failure

	// Check if we'll load across a page boundary.
	LEAQ	16(SI), AX
	TESTW	$0xff0, AX
	JEQ	endofpage

	MOVOU	(SI), X1 // Load data
	PCMPEQB	X0, X1	// Compare target byte with each byte in data.
	PMOVMSKB X1, DX	// Move result bits to integer register.
	BSFL	DX, DX	// Find first set bit.
	JZ	failure	// No set bit, failure.
	CMPL	DX, BX
	JAE	failure	// Match is past end of data.
	MOVQ	DX, (R8)
	RET

endofpage:
	MOVOU	-16(SI)(BX*1), X1	// Load data into the high end of X1.
	PCMPEQB	X0, X1	// Compare target byte with each byte in data.
	PMOVMSKB X1, DX	// Move result bits to integer register.
	MOVL	BX, CX
	SHLL	CX, DX
	SHRL	$16, DX	// Shift desired bits down to bottom of register.
	BSFL	DX, DX	// Find first set bit.
	JZ	failure	// No set bit, failure.
	MOVQ	DX, (R8)
	RET

avx2:
	CMPB   internalcpu·X86+const_offsetX86HasAVX2(SB), $1
	JNE sse
	MOVD AX, X0
	LEAQ -32(SI)(BX*1), R11
	VPBROADCASTB  X0, Y1
avx2_loop:
	VMOVDQU (DI), Y2
	VPCMPEQB Y1, Y2, Y3
	VPTEST Y3, Y3
	JNZ avx2success
	ADDQ $32, DI
	CMPQ DI, R11
	JLT avx2_loop
	MOVQ R11, DI
	VMOVDQU (DI), Y2
	VPCMPEQB Y1, Y2, Y3
	VPTEST Y3, Y3
	JNZ avx2success
	VZEROUPPER
	MOVQ $-1, (R8)
	RET

avx2success:
	VPMOVMSKB Y3, DX
	BSFL DX, DX
	SUBQ SI, DI
	ADDQ DI, DX
	MOVQ DX, (R8)
	VZEROUPPER
	RET