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
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
|
// 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.
/*
Package arm64 implements an ARM64 assembler. Go assembly syntax is different from GNU ARM64
syntax, but we can still follow the general rules to map between them.
Instructions mnemonics mapping rules
1. Most instructions use width suffixes of instruction names to indicate operand width rather than
using different register names.
Examples:
ADC R24, R14, R12 <=> adc x12, x24
ADDW R26->24, R21, R15 <=> add w15, w21, w26, asr #24
FCMPS F2, F3 <=> fcmp s3, s2
FCMPD F2, F3 <=> fcmp d3, d2
FCVTDH F2, F3 <=> fcvt h3, d2
2. Go uses .P and .W suffixes to indicate post-increment and pre-increment.
Examples:
MOVD.P -8(R10), R8 <=> ldr x8, [x10],#-8
MOVB.W 16(R16), R10 <=> ldrsb x10, [x16,#16]!
MOVBU.W 16(R16), R10 <=> ldrb x10, [x16,#16]!
3. Go uses a series of MOV instructions as load and store.
64-bit variant ldr, str, stur => MOVD;
32-bit variant str, stur, ldrsw => MOVW;
32-bit variant ldr => MOVWU;
ldrb => MOVBU; ldrh => MOVHU;
ldrsb, sturb, strb => MOVB;
ldrsh, sturh, strh => MOVH.
4. Go moves conditions into opcode suffix, like BLT.
5. Go adds a V prefix for most floating-point and SIMD instructions, except cryptographic extension
instructions and floating-point(scalar) instructions.
Examples:
VADD V5.H8, V18.H8, V9.H8 <=> add v9.8h, v18.8h, v5.8h
VLD1.P (R6)(R11), [V31.D1] <=> ld1 {v31.1d}, [x6], x11
VFMLA V29.S2, V20.S2, V14.S2 <=> fmla v14.2s, v20.2s, v29.2s
AESD V22.B16, V19.B16 <=> aesd v19.16b, v22.16b
SCVTFWS R3, F16 <=> scvtf s17, w6
6. Align directive
Go asm supports the PCALIGN directive, which indicates that the next instruction should be aligned
to a specified boundary by padding with NOOP instruction. The alignment value supported on arm64
must be a power of 2 and in the range of [8, 2048].
Examples:
PCALIGN $16
MOVD $2, R0 // This instruction is aligned with 16 bytes.
PCALIGN $1024
MOVD $3, R1 // This instruction is aligned with 1024 bytes.
PCALIGN also changes the function alignment. If a function has one or more PCALIGN directives,
its address will be aligned to the same or coarser boundary, which is the maximum of all the
alignment values.
In the following example, the function Add is aligned with 128 bytes.
Examples:
TEXT ·Add(SB),$40-16
MOVD $2, R0
PCALIGN $32
MOVD $4, R1
PCALIGN $128
MOVD $8, R2
RET
On arm64, functions in Go are aligned to 16 bytes by default, we can also use PCALGIN to set the
function alignment. The functions that need to be aligned are preferably using NOFRAME and NOSPLIT
to avoid the impact of the prologues inserted by the assembler, so that the function address will
have the same alignment as the first hand-written instruction.
In the following example, PCALIGN at the entry of the function Add will align its address to 2048 bytes.
Examples:
TEXT ·Add(SB),NOSPLIT|NOFRAME,$0
PCALIGN $2048
MOVD $1, R0
MOVD $1, R1
RET
7. Move large constants to vector registers.
Go asm uses VMOVQ/VMOVD/VMOVS to move 128-bit, 64-bit and 32-bit constants into vector registers, respectively.
And for a 128-bit interger, it take two 64-bit operands, for the high and low parts separately.
Examples:
VMOVS $0x11223344, V0
VMOVD $0x1122334455667788, V1
VMOVQ $0x1122334455667788, $8877665544332211, V2 // V2=0x11223344556677888877665544332211
8. Move an optionally-shifted 16-bit immediate value to a register.
The instructions are MOVK(W), MOVZ(W) and MOVN(W), the assembly syntax is "op $(uimm16<<shift), <Rd>". The <uimm16>
is the 16-bit unsigned immediate, in the range 0 to 65535; For the 32-bit variant, the <shift> is 0 or 16, for the
64-bit variant, the <shift> is 0, 16, 32 or 48.
The current Go assembler does not accept zero shifts, such as "op $0, Rd" and "op $(0<<(16|32|48)), Rd" instructions.
Examples:
MOVK $(10<<32), R20 <=> movk x20, #10, lsl #32
MOVZW $(20<<16), R8 <=> movz w8, #20, lsl #16
MOVK $(0<<16), R10 will be reported as an error by the assembler.
Special Cases.
(1) umov is written as VMOV.
(2) br is renamed JMP, blr is renamed CALL.
(3) No need to add "W" suffix: LDARB, LDARH, LDAXRB, LDAXRH, LDTRH, LDXRB, LDXRH.
(4) In Go assembly syntax, NOP is a zero-width pseudo-instruction serves generic purpose, nothing
related to real ARM64 instruction. NOOP serves for the hardware nop instruction. NOOP is an alias of
HINT $0.
Examples:
VMOV V13.B[1], R20 <=> mov x20, v13.b[1]
VMOV V13.H[1], R20 <=> mov w20, v13.h[1]
JMP (R3) <=> br x3
CALL (R17) <=> blr x17
LDAXRB (R19), R16 <=> ldaxrb w16, [x19]
NOOP <=> nop
Register mapping rules
1. All basic register names are written as Rn.
2. Go uses ZR as the zero register and RSP as the stack pointer.
3. Bn, Hn, Dn, Sn and Qn instructions are written as Fn in floating-point instructions and as Vn
in SIMD instructions.
Argument mapping rules
1. The operands appear in left-to-right assignment order.
Go reverses the arguments of most instructions.
Examples:
ADD R11.SXTB<<1, RSP, R25 <=> add x25, sp, w11, sxtb #1
VADD V16, V19, V14 <=> add d14, d19, d16
Special Cases.
(1) Argument order is the same as in the GNU ARM64 syntax: cbz, cbnz and some store instructions,
such as str, stur, strb, sturb, strh, sturh stlr, stlrb. stlrh, st1.
Examples:
MOVD R29, 384(R19) <=> str x29, [x19,#384]
MOVB.P R30, 30(R4) <=> strb w30, [x4],#30
STLRH R21, (R19) <=> stlrh w21, [x19]
(2) MADD, MADDW, MSUB, MSUBW, SMADDL, SMSUBL, UMADDL, UMSUBL <Rm>, <Ra>, <Rn>, <Rd>
Examples:
MADD R2, R30, R22, R6 <=> madd x6, x22, x2, x30
SMSUBL R10, R3, R17, R27 <=> smsubl x27, w17, w10, x3
(3) FMADDD, FMADDS, FMSUBD, FMSUBS, FNMADDD, FNMADDS, FNMSUBD, FNMSUBS <Fm>, <Fa>, <Fn>, <Fd>
Examples:
FMADDD F30, F20, F3, F29 <=> fmadd d29, d3, d30, d20
FNMSUBS F7, F25, F7, F22 <=> fnmsub s22, s7, s7, s25
(4) BFI, BFXIL, SBFIZ, SBFX, UBFIZ, UBFX $<lsb>, <Rn>, $<width>, <Rd>
Examples:
BFIW $16, R20, $6, R0 <=> bfi w0, w20, #16, #6
UBFIZ $34, R26, $5, R20 <=> ubfiz x20, x26, #34, #5
(5) FCCMPD, FCCMPS, FCCMPED, FCCMPES <cond>, Fm. Fn, $<nzcv>
Examples:
FCCMPD AL, F8, F26, $0 <=> fccmp d26, d8, #0x0, al
FCCMPS VS, F29, F4, $4 <=> fccmp s4, s29, #0x4, vs
FCCMPED LE, F20, F5, $13 <=> fccmpe d5, d20, #0xd, le
FCCMPES NE, F26, F10, $0 <=> fccmpe s10, s26, #0x0, ne
(6) CCMN, CCMNW, CCMP, CCMPW <cond>, <Rn>, $<imm>, $<nzcv>
Examples:
CCMP MI, R22, $12, $13 <=> ccmp x22, #0xc, #0xd, mi
CCMNW AL, R1, $11, $8 <=> ccmn w1, #0xb, #0x8, al
(7) CCMN, CCMNW, CCMP, CCMPW <cond>, <Rn>, <Rm>, $<nzcv>
Examples:
CCMN VS, R13, R22, $10 <=> ccmn x13, x22, #0xa, vs
CCMPW HS, R19, R14, $11 <=> ccmp w19, w14, #0xb, cs
(9) CSEL, CSELW, CSNEG, CSNEGW, CSINC, CSINCW <cond>, <Rn>, <Rm>, <Rd> ;
FCSELD, FCSELS <cond>, <Fn>, <Fm>, <Fd>
Examples:
CSEL GT, R0, R19, R1 <=> csel x1, x0, x19, gt
CSNEGW GT, R7, R17, R8 <=> csneg w8, w7, w17, gt
FCSELD EQ, F15, F18, F16 <=> fcsel d16, d15, d18, eq
(10) TBNZ, TBZ $<imm>, <Rt>, <label>
(11) STLXR, STLXRW, STXR, STXRW, STLXRB, STLXRH, STXRB, STXRH <Rf>, (<Rn|RSP>), <Rs>
Examples:
STLXR ZR, (R15), R16 <=> stlxr w16, xzr, [x15]
STXRB R9, (R21), R19 <=> stxrb w19, w9, [x21]
(12) STLXP, STLXPW, STXP, STXPW (<Rf1>, <Rf2>), (<Rn|RSP>), <Rs>
Examples:
STLXP (R17, R19), (R4), R5 <=> stlxp w5, x17, x19, [x4]
STXPW (R30, R25), (R22), R13 <=> stxp w13, w30, w25, [x22]
2. Expressions for special arguments.
#<immediate> is written as $<immediate>.
Optionally-shifted immediate.
Examples:
ADD $(3151<<12), R14, R20 <=> add x20, x14, #0xc4f, lsl #12
ADDW $1864, R25, R6 <=> add w6, w25, #0x748
Optionally-shifted registers are written as <Rm>{<shift><amount>}.
The <shift> can be <<(lsl), >>(lsr), ->(asr), @>(ror).
Examples:
ADD R19>>30, R10, R24 <=> add x24, x10, x19, lsr #30
ADDW R26->24, R21, R15 <=> add w15, w21, w26, asr #24
Extended registers are written as <Rm>{.<extend>{<<<amount>}}.
<extend> can be UXTB, UXTH, UXTW, UXTX, SXTB, SXTH, SXTW or SXTX.
Examples:
ADDS R19.UXTB<<4, R9, R26 <=> adds x26, x9, w19, uxtb #4
ADDSW R14.SXTX, R14, R6 <=> adds w6, w14, w14, sxtx
Memory references: [<Xn|SP>{,#0}] is written as (Rn|RSP), a base register and an immediate
offset is written as imm(Rn|RSP), a base register and an offset register is written as (Rn|RSP)(Rm).
Examples:
LDAR (R22), R9 <=> ldar x9, [x22]
LDP 28(R17), (R15, R23) <=> ldp x15, x23, [x17,#28]
MOVWU (R4)(R12<<2), R8 <=> ldr w8, [x4, x12, lsl #2]
MOVD (R7)(R11.UXTW<<3), R25 <=> ldr x25, [x7,w11,uxtw #3]
MOVBU (R27)(R23), R14 <=> ldrb w14, [x27,x23]
Register pairs are written as (Rt1, Rt2).
Examples:
LDP.P -240(R11), (R12, R26) <=> ldp x12, x26, [x11],#-240
Register with arrangement and register with arrangement and index.
Examples:
VADD V5.H8, V18.H8, V9.H8 <=> add v9.8h, v18.8h, v5.8h
VLD1 (R2), [V21.B16] <=> ld1 {v21.16b}, [x2]
VST1.P V9.S[1], (R16)(R21) <=> st1 {v9.s}[1], [x16], x28
VST1.P [V13.H8, V14.H8, V15.H8], (R3)(R14) <=> st1 {v13.8h-v15.8h}, [x3], x14
VST1.P [V14.D1, V15.D1], (R7)(R23) <=> st1 {v14.1d, v15.1d}, [x7], x23
*/
package arm64
|
