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,$0-13
10 MOVL a+0(FP), SI
11 MOVL b+4(FP), DI
12 CMPL SI, DI
13 JEQ eq
14 MOVL size+8(FP), BX
15 LEAL ret+12(FP), AX
16 JMP memeqbody<>(SB)
17 eq:
18 MOVB $1, ret+12(FP)
19 RET
20
21 // memequal_varlen(a, b unsafe.Pointer) bool
22 TEXT runtime·memequal_varlen(SB),NOSPLIT,$0-9
23 MOVL a+0(FP), SI
24 MOVL b+4(FP), DI
25 CMPL SI, DI
26 JEQ eq
27 MOVL 4(DX), BX // compiler stores size at offset 4 in the closure
28 LEAL ret+8(FP), AX
29 JMP memeqbody<>(SB)
30 eq:
31 MOVB $1, ret+8(FP)
32 RET
33
34 // a in SI
35 // b in DI
36 // count in BX
37 // address of result byte in AX
38 TEXT memeqbody<>(SB),NOSPLIT,$0-0
39 CMPL BX, $4
40 JB small
41
42 // 64 bytes at a time using xmm registers
43 hugeloop:
44 CMPL BX, $64
45 JB bigloop
46 CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1
47 JNE bigloop
48 MOVOU (SI), X0
49 MOVOU (DI), X1
50 MOVOU 16(SI), X2
51 MOVOU 16(DI), X3
52 MOVOU 32(SI), X4
53 MOVOU 32(DI), X5
54 MOVOU 48(SI), X6
55 MOVOU 48(DI), X7
56 PCMPEQB X1, X0
57 PCMPEQB X3, X2
58 PCMPEQB X5, X4
59 PCMPEQB X7, X6
60 PAND X2, X0
61 PAND X6, X4
62 PAND X4, X0
63 PMOVMSKB X0, DX
64 ADDL $64, SI
65 ADDL $64, DI
66 SUBL $64, BX
67 CMPL DX, $0xffff
68 JEQ hugeloop
69 MOVB $0, (AX)
70 RET
71
72 // 4 bytes at a time using 32-bit register
73 bigloop:
74 CMPL BX, $4
75 JBE leftover
76 MOVL (SI), CX
77 MOVL (DI), DX
78 ADDL $4, SI
79 ADDL $4, DI
80 SUBL $4, BX
81 CMPL CX, DX
82 JEQ bigloop
83 MOVB $0, (AX)
84 RET
85
86 // remaining 0-4 bytes
87 leftover:
88 MOVL -4(SI)(BX*1), CX
89 MOVL -4(DI)(BX*1), DX
90 CMPL CX, DX
91 SETEQ (AX)
92 RET
93
94 small:
95 CMPL BX, $0
96 JEQ equal
97
98 LEAL 0(BX*8), CX
99 NEGL CX
100
101 MOVL SI, DX
102 CMPB DX, $0xfc
103 JA si_high
104
105 // load at SI won't cross a page boundary.
106 MOVL (SI), SI
107 JMP si_finish
108 si_high:
109 // address ends in 111111xx. Load up to bytes we want, move to correct position.
110 MOVL -4(SI)(BX*1), SI
111 SHRL CX, SI
112 si_finish:
113
114 // same for DI.
115 MOVL DI, DX
116 CMPB DX, $0xfc
117 JA di_high
118 MOVL (DI), DI
119 JMP di_finish
120 di_high:
121 MOVL -4(DI)(BX*1), DI
122 SHRL CX, DI
123 di_finish:
124
125 SUBL SI, DI
126 SHLL CX, DI
127 equal:
128 SETEQ (AX)
129 RET
130
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