1 //===-- EmulateInstructionARM64.cpp ---------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "EmulateInstructionARM64.h"
10 
11 #include "lldb/Core/Address.h"
12 #include "lldb/Core/PluginManager.h"
13 #include "lldb/Symbol/UnwindPlan.h"
14 #include "lldb/Utility/ArchSpec.h"
15 #include "lldb/Utility/RegisterValue.h"
16 #include "lldb/Utility/Stream.h"
17 
18 #include "llvm/Support/CheckedArithmetic.h"
19 
20 #include "Plugins/Process/Utility/ARMDefines.h"
21 #include "Plugins/Process/Utility/ARMUtils.h"
22 #include "Plugins/Process/Utility/lldb-arm64-register-enums.h"
23 
24 #include <algorithm>
25 #include <cstdlib>
26 #include <optional>
27 
28 #define GPR_OFFSET(idx) ((idx)*8)
29 #define GPR_OFFSET_NAME(reg) 0
30 #define FPU_OFFSET(idx) ((idx)*16)
31 #define FPU_OFFSET_NAME(reg) 0
32 #define EXC_OFFSET_NAME(reg) 0
33 #define DBG_OFFSET_NAME(reg) 0
34 #define DBG_OFFSET_NAME(reg) 0
35 #define DEFINE_DBG(re, y)                                                      \
36   "na", nullptr, 8, 0, lldb::eEncodingUint, lldb::eFormatHex,                  \
37       {LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,          \
38        LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM},                              \
39       nullptr, nullptr, nullptr
40 
41 #define DECLARE_REGISTER_INFOS_ARM64_STRUCT
42 
43 #include "Plugins/Process/Utility/RegisterInfos_arm64.h"
44 
45 #include "llvm/ADT/STLExtras.h"
46 #include "llvm/Support/MathExtras.h"
47 
48 #include "Plugins/Process/Utility/InstructionUtils.h"
49 
50 using namespace lldb;
51 using namespace lldb_private;
52 
53 LLDB_PLUGIN_DEFINE_ADV(EmulateInstructionARM64, InstructionARM64)
54 
55 static std::optional<RegisterInfo> LLDBTableGetRegisterInfo(uint32_t reg_num) {
56   if (reg_num >= std::size(g_register_infos_arm64_le))
57     return {};
58   return g_register_infos_arm64_le[reg_num];
59 }
60 
61 #define No_VFP 0
62 #define VFPv1 (1u << 1)
63 #define VFPv2 (1u << 2)
64 #define VFPv3 (1u << 3)
65 #define AdvancedSIMD (1u << 4)
66 
67 #define VFPv1_ABOVE (VFPv1 | VFPv2 | VFPv3 | AdvancedSIMD)
68 #define VFPv2_ABOVE (VFPv2 | VFPv3 | AdvancedSIMD)
69 #define VFPv2v3 (VFPv2 | VFPv3)
70 
71 #define UInt(x) ((uint64_t)x)
72 #define SInt(x) ((int64_t)x)
73 #define bit bool
74 #define boolean bool
75 #define integer int64_t
76 
77 static inline bool IsZero(uint64_t x) { return x == 0; }
78 
79 static inline uint64_t NOT(uint64_t x) { return ~x; }
80 
81 // LSL()
82 // =====
83 
84 static inline uint64_t LSL(uint64_t x, integer shift) {
85   if (shift == 0)
86     return x;
87   return x << shift;
88 }
89 
90 // ConstrainUnpredictable()
91 // ========================
92 
93 EmulateInstructionARM64::ConstraintType
94 ConstrainUnpredictable(EmulateInstructionARM64::Unpredictable which) {
95   EmulateInstructionARM64::ConstraintType result =
96       EmulateInstructionARM64::Constraint_UNKNOWN;
97   switch (which) {
98   case EmulateInstructionARM64::Unpredictable_WBOVERLAP:
99   case EmulateInstructionARM64::Unpredictable_LDPOVERLAP:
100     // TODO: don't know what to really do here? Pseudo code says:
101     // set result to one of above Constraint behaviours or UNDEFINED
102     break;
103   }
104   return result;
105 }
106 
107 //
108 // EmulateInstructionARM implementation
109 //
110 
111 void EmulateInstructionARM64::Initialize() {
112   PluginManager::RegisterPlugin(GetPluginNameStatic(),
113                                 GetPluginDescriptionStatic(), CreateInstance);
114 }
115 
116 void EmulateInstructionARM64::Terminate() {
117   PluginManager::UnregisterPlugin(CreateInstance);
118 }
119 
120 llvm::StringRef EmulateInstructionARM64::GetPluginDescriptionStatic() {
121   return "Emulate instructions for the ARM64 architecture.";
122 }
123 
124 EmulateInstruction *
125 EmulateInstructionARM64::CreateInstance(const ArchSpec &arch,
126                                         InstructionType inst_type) {
127   if (EmulateInstructionARM64::SupportsEmulatingInstructionsOfTypeStatic(
128           inst_type)) {
129     if (arch.GetTriple().getArch() == llvm::Triple::aarch64 ||
130         arch.GetTriple().getArch() == llvm::Triple::aarch64_32) {
131       return new EmulateInstructionARM64(arch);
132     }
133   }
134 
135   return nullptr;
136 }
137 
138 bool EmulateInstructionARM64::SetTargetTriple(const ArchSpec &arch) {
139   if (arch.GetTriple().getArch() == llvm::Triple::arm)
140     return true;
141   else if (arch.GetTriple().getArch() == llvm::Triple::thumb)
142     return true;
143 
144   return false;
145 }
146 
147 std::optional<RegisterInfo>
148 EmulateInstructionARM64::GetRegisterInfo(RegisterKind reg_kind,
149                                          uint32_t reg_num) {
150   if (reg_kind == eRegisterKindGeneric) {
151     switch (reg_num) {
152     case LLDB_REGNUM_GENERIC_PC:
153       reg_kind = eRegisterKindLLDB;
154       reg_num = gpr_pc_arm64;
155       break;
156     case LLDB_REGNUM_GENERIC_SP:
157       reg_kind = eRegisterKindLLDB;
158       reg_num = gpr_sp_arm64;
159       break;
160     case LLDB_REGNUM_GENERIC_FP:
161       reg_kind = eRegisterKindLLDB;
162       reg_num = gpr_fp_arm64;
163       break;
164     case LLDB_REGNUM_GENERIC_RA:
165       reg_kind = eRegisterKindLLDB;
166       reg_num = gpr_lr_arm64;
167       break;
168     case LLDB_REGNUM_GENERIC_FLAGS:
169       reg_kind = eRegisterKindLLDB;
170       reg_num = gpr_cpsr_arm64;
171       break;
172 
173     default:
174       return {};
175     }
176   }
177 
178   if (reg_kind == eRegisterKindLLDB)
179     return LLDBTableGetRegisterInfo(reg_num);
180   return {};
181 }
182 
183 EmulateInstructionARM64::Opcode *
184 EmulateInstructionARM64::GetOpcodeForInstruction(const uint32_t opcode) {
185   static EmulateInstructionARM64::Opcode g_opcodes[] = {
186       // Prologue instructions
187 
188       // push register(s)
189       {0xff000000, 0xd1000000, No_VFP,
190        &EmulateInstructionARM64::EmulateADDSUBImm,
191        "SUB  <Xd|SP>, <Xn|SP>, #<imm> {, <shift>}"},
192       {0xff000000, 0xf1000000, No_VFP,
193        &EmulateInstructionARM64::EmulateADDSUBImm,
194        "SUBS  <Xd>, <Xn|SP>, #<imm> {, <shift>}"},
195       {0xff000000, 0x91000000, No_VFP,
196        &EmulateInstructionARM64::EmulateADDSUBImm,
197        "ADD  <Xd|SP>, <Xn|SP>, #<imm> {, <shift>}"},
198       {0xff000000, 0xb1000000, No_VFP,
199        &EmulateInstructionARM64::EmulateADDSUBImm,
200        "ADDS  <Xd>, <Xn|SP>, #<imm> {, <shift>}"},
201 
202       {0xff000000, 0x51000000, No_VFP,
203        &EmulateInstructionARM64::EmulateADDSUBImm,
204        "SUB  <Wd|WSP>, <Wn|WSP>, #<imm> {, <shift>}"},
205       {0xff000000, 0x71000000, No_VFP,
206        &EmulateInstructionARM64::EmulateADDSUBImm,
207        "SUBS  <Wd>, <Wn|WSP>, #<imm> {, <shift>}"},
208       {0xff000000, 0x11000000, No_VFP,
209        &EmulateInstructionARM64::EmulateADDSUBImm,
210        "ADD  <Wd|WSP>, <Wn|WSP>, #<imm> {, <shift>}"},
211       {0xff000000, 0x31000000, No_VFP,
212        &EmulateInstructionARM64::EmulateADDSUBImm,
213        "ADDS  <Wd>, <Wn|WSP>, #<imm> {, <shift>}"},
214 
215       {0xffc00000, 0x29000000, No_VFP,
216        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
217        "STP  <Wt>, <Wt2>, [<Xn|SP>{, #<imm>}]"},
218       {0xffc00000, 0xa9000000, No_VFP,
219        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
220        "STP  <Xt>, <Xt2>, [<Xn|SP>{, #<imm>}]"},
221       {0xffc00000, 0x2d000000, No_VFP,
222        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
223        "STP  <St>, <St2>, [<Xn|SP>{, #<imm>}]"},
224       {0xffc00000, 0x6d000000, No_VFP,
225        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
226        "STP  <Dt>, <Dt2>, [<Xn|SP>{, #<imm>}]"},
227       {0xffc00000, 0xad000000, No_VFP,
228        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
229        "STP  <Qt>, <Qt2>, [<Xn|SP>{, #<imm>}]"},
230 
231       {0xffc00000, 0x29800000, No_VFP,
232        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
233        "STP  <Wt>, <Wt2>, [<Xn|SP>, #<imm>]!"},
234       {0xffc00000, 0xa9800000, No_VFP,
235        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
236        "STP  <Xt>, <Xt2>, [<Xn|SP>, #<imm>]!"},
237       {0xffc00000, 0x2d800000, No_VFP,
238        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
239        "STP  <St>, <St2>, [<Xn|SP>, #<imm>]!"},
240       {0xffc00000, 0x6d800000, No_VFP,
241        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
242        "STP  <Dt>, <Dt2>, [<Xn|SP>, #<imm>]!"},
243       {0xffc00000, 0xad800000, No_VFP,
244        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
245        "STP  <Qt>, <Qt2>, [<Xn|SP>, #<imm>]!"},
246 
247       {0xffc00000, 0x28800000, No_VFP,
248        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
249        "STP  <Wt>, <Wt2>, [<Xn|SP>, #<imm>]!"},
250       {0xffc00000, 0xa8800000, No_VFP,
251        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
252        "STP  <Xt>, <Xt2>, [<Xn|SP>, #<imm>]!"},
253       {0xffc00000, 0x2c800000, No_VFP,
254        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
255        "STP  <St>, <St2>, [<Xn|SP>, #<imm>]!"},
256       {0xffc00000, 0x6c800000, No_VFP,
257        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
258        "STP  <Dt>, <Dt2>, [<Xn|SP>, #<imm>]!"},
259       {0xffc00000, 0xac800000, No_VFP,
260        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
261        "STP  <Qt>, <Qt2>, [<Xn|SP>, #<imm>]!"},
262 
263       {0xffc00000, 0x29400000, No_VFP,
264        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
265        "LDP  <Wt>, <Wt2>, [<Xn|SP>{, #<imm>}]"},
266       {0xffc00000, 0xa9400000, No_VFP,
267        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
268        "LDP  <Xt>, <Xt2>, [<Xn|SP>{, #<imm>}]"},
269       {0xffc00000, 0x2d400000, No_VFP,
270        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
271        "LDP  <St>, <St2>, [<Xn|SP>{, #<imm>}]"},
272       {0xffc00000, 0x6d400000, No_VFP,
273        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
274        "LDP  <Dt>, <Dt2>, [<Xn|SP>{, #<imm>}]"},
275       {0xffc00000, 0xad400000, No_VFP,
276        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_OFF>,
277        "LDP  <Qt>, <Qt2>, [<Xn|SP>{, #<imm>}]"},
278 
279       {0xffc00000, 0x29c00000, No_VFP,
280        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
281        "LDP  <Wt>, <Wt2>, [<Xn|SP>, #<imm>]!"},
282       {0xffc00000, 0xa9c00000, No_VFP,
283        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
284        "LDP  <Xt>, <Xt2>, [<Xn|SP>, #<imm>]!"},
285       {0xffc00000, 0x2dc00000, No_VFP,
286        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
287        "LDP  <St>, <St2>, [<Xn|SP>, #<imm>]!"},
288       {0xffc00000, 0x6dc00000, No_VFP,
289        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
290        "LDP  <Dt>, <Dt2>, [<Xn|SP>, #<imm>]!"},
291       {0xffc00000, 0xadc00000, No_VFP,
292        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_PRE>,
293        "LDP  <Qt>, <Qt2>, [<Xn|SP>, #<imm>]!"},
294 
295       {0xffc00000, 0x28c00000, No_VFP,
296        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
297        "LDP  <Wt>, <Wt2>, [<Xn|SP>, #<imm>]!"},
298       {0xffc00000, 0xa8c00000, No_VFP,
299        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
300        "LDP  <Xt>, <Xt2>, [<Xn|SP>, #<imm>]!"},
301       {0xffc00000, 0x2cc00000, No_VFP,
302        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
303        "LDP  <St>, <St2>, [<Xn|SP>, #<imm>]!"},
304       {0xffc00000, 0x6cc00000, No_VFP,
305        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
306        "LDP  <Dt>, <Dt2>, [<Xn|SP>, #<imm>]!"},
307       {0xffc00000, 0xacc00000, No_VFP,
308        &EmulateInstructionARM64::EmulateLDPSTP<AddrMode_POST>,
309        "LDP  <Qt>, <Qt2>, [<Xn|SP>, #<imm>]!"},
310 
311       {0xffe00c00, 0xb8000400, No_VFP,
312        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_POST>,
313        "STR <Wt>, [<Xn|SP>], #<simm>"},
314       {0xffe00c00, 0xf8000400, No_VFP,
315        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_POST>,
316        "STR <Xt>, [<Xn|SP>], #<simm>"},
317       {0xffe00c00, 0xb8000c00, No_VFP,
318        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_PRE>,
319        "STR <Wt>, [<Xn|SP>, #<simm>]!"},
320       {0xffe00c00, 0xf8000c00, No_VFP,
321        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_PRE>,
322        "STR <Xt>, [<Xn|SP>, #<simm>]!"},
323       {0xffc00000, 0xb9000000, No_VFP,
324        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_OFF>,
325        "STR <Wt>, [<Xn|SP>{, #<pimm>}]"},
326       {0xffc00000, 0xf9000000, No_VFP,
327        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_OFF>,
328        "STR <Xt>, [<Xn|SP>{, #<pimm>}]"},
329 
330       {0xffe00c00, 0xb8400400, No_VFP,
331        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_POST>,
332        "LDR <Wt>, [<Xn|SP>], #<simm>"},
333       {0xffe00c00, 0xf8400400, No_VFP,
334        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_POST>,
335        "LDR <Xt>, [<Xn|SP>], #<simm>"},
336       {0xffe00c00, 0xb8400c00, No_VFP,
337        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_PRE>,
338        "LDR <Wt>, [<Xn|SP>, #<simm>]!"},
339       {0xffe00c00, 0xf8400c00, No_VFP,
340        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_PRE>,
341        "LDR <Xt>, [<Xn|SP>, #<simm>]!"},
342       {0xffc00000, 0xb9400000, No_VFP,
343        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_OFF>,
344        "LDR <Wt>, [<Xn|SP>{, #<pimm>}]"},
345       {0xffc00000, 0xf9400000, No_VFP,
346        &EmulateInstructionARM64::EmulateLDRSTRImm<AddrMode_OFF>,
347        "LDR <Xt>, [<Xn|SP>{, #<pimm>}]"},
348 
349       {0xfc000000, 0x14000000, No_VFP, &EmulateInstructionARM64::EmulateB,
350        "B <label>"},
351       {0xff000010, 0x54000000, No_VFP, &EmulateInstructionARM64::EmulateBcond,
352        "B.<cond> <label>"},
353       {0x7f000000, 0x34000000, No_VFP, &EmulateInstructionARM64::EmulateCBZ,
354        "CBZ <Wt>, <label>"},
355       {0x7f000000, 0x35000000, No_VFP, &EmulateInstructionARM64::EmulateCBZ,
356        "CBNZ <Wt>, <label>"},
357       {0x7f000000, 0x36000000, No_VFP, &EmulateInstructionARM64::EmulateTBZ,
358        "TBZ <R><t>, #<imm>, <label>"},
359       {0x7f000000, 0x37000000, No_VFP, &EmulateInstructionARM64::EmulateTBZ,
360        "TBNZ <R><t>, #<imm>, <label>"},
361 
362   };
363   static const size_t k_num_arm_opcodes = std::size(g_opcodes);
364 
365   for (size_t i = 0; i < k_num_arm_opcodes; ++i) {
366     if ((g_opcodes[i].mask & opcode) == g_opcodes[i].value)
367       return &g_opcodes[i];
368   }
369   return nullptr;
370 }
371 
372 bool EmulateInstructionARM64::ReadInstruction() {
373   bool success = false;
374   m_addr = ReadRegisterUnsigned(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC,
375                                 LLDB_INVALID_ADDRESS, &success);
376   if (success) {
377     Context read_inst_context;
378     read_inst_context.type = eContextReadOpcode;
379     read_inst_context.SetNoArgs();
380     m_opcode.SetOpcode32(
381         ReadMemoryUnsigned(read_inst_context, m_addr, 4, 0, &success),
382         GetByteOrder());
383   }
384   if (!success)
385     m_addr = LLDB_INVALID_ADDRESS;
386   return success;
387 }
388 
389 bool EmulateInstructionARM64::EvaluateInstruction(uint32_t evaluate_options) {
390   const uint32_t opcode = m_opcode.GetOpcode32();
391   Opcode *opcode_data = GetOpcodeForInstruction(opcode);
392   if (opcode_data == nullptr)
393     return false;
394 
395   const bool auto_advance_pc =
396       evaluate_options & eEmulateInstructionOptionAutoAdvancePC;
397   m_ignore_conditions =
398       evaluate_options & eEmulateInstructionOptionIgnoreConditions;
399 
400   bool success = false;
401 
402   // Only return false if we are unable to read the CPSR if we care about
403   // conditions
404   if (!success && !m_ignore_conditions)
405     return false;
406 
407   uint32_t orig_pc_value = 0;
408   if (auto_advance_pc) {
409     orig_pc_value =
410         ReadRegisterUnsigned(eRegisterKindLLDB, gpr_pc_arm64, 0, &success);
411     if (!success)
412       return false;
413   }
414 
415   // Call the Emulate... function.
416   success = (this->*opcode_data->callback)(opcode);
417   if (!success)
418     return false;
419 
420   if (auto_advance_pc) {
421     uint32_t new_pc_value =
422         ReadRegisterUnsigned(eRegisterKindLLDB, gpr_pc_arm64, 0, &success);
423     if (!success)
424       return false;
425 
426     if (new_pc_value == orig_pc_value) {
427       EmulateInstruction::Context context;
428       context.type = eContextAdvancePC;
429       context.SetNoArgs();
430       if (!WriteRegisterUnsigned(context, eRegisterKindLLDB, gpr_pc_arm64,
431                                  orig_pc_value + 4))
432         return false;
433     }
434   }
435   return true;
436 }
437 
438 bool EmulateInstructionARM64::CreateFunctionEntryUnwind(
439     UnwindPlan &unwind_plan) {
440   unwind_plan.Clear();
441   unwind_plan.SetRegisterKind(eRegisterKindLLDB);
442 
443   UnwindPlan::RowSP row(new UnwindPlan::Row);
444 
445   // Our previous Call Frame Address is the stack pointer
446   row->GetCFAValue().SetIsRegisterPlusOffset(gpr_sp_arm64, 0);
447 
448   unwind_plan.AppendRow(row);
449   unwind_plan.SetSourceName("EmulateInstructionARM64");
450   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
451   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
452   unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
453   unwind_plan.SetReturnAddressRegister(gpr_lr_arm64);
454   return true;
455 }
456 
457 uint32_t EmulateInstructionARM64::GetFramePointerRegisterNumber() const {
458   if (m_arch.GetTriple().isAndroid())
459     return LLDB_INVALID_REGNUM; // Don't use frame pointer on android
460 
461   return gpr_fp_arm64;
462 }
463 
464 bool EmulateInstructionARM64::UsingAArch32() {
465   bool aarch32 = m_opcode_pstate.RW == 1;
466   // if !HaveAnyAArch32() then assert !aarch32;
467   // if HighestELUsingAArch32() then assert aarch32;
468   return aarch32;
469 }
470 
471 bool EmulateInstructionARM64::BranchTo(const Context &context, uint32_t N,
472                                        addr_t target) {
473 #if 0
474     // Set program counter to a new address, with a branch reason hint for
475     // possible use by hardware fetching the next instruction.
476     BranchTo(bits(N) target, BranchType branch_type)
477         Hint_Branch(branch_type);
478         if N == 32 then
479             assert UsingAArch32();
480             _PC = ZeroExtend(target);
481         else
482             assert N == 64 && !UsingAArch32();
483             // Remove the tag bits from a tagged target
484             case PSTATE.EL of
485                 when EL0, EL1
486                     if target<55> == '1' && TCR_EL1.TBI1 == '1' then
487                         target<63:56> = '11111111';
488                     if target<55> == '0' && TCR_EL1.TBI0 == '1' then
489                         target<63:56> = '00000000';
490                 when EL2
491                     if TCR_EL2.TBI == '1' then
492                         target<63:56> = '00000000';
493                 when EL3
494                     if TCR_EL3.TBI == '1' then
495                         target<63:56> = '00000000';
496         _PC = target<63:0>;
497         return;
498 #endif
499 
500   addr_t addr;
501 
502   // Hint_Branch(branch_type);
503   if (N == 32) {
504     if (!UsingAArch32())
505       return false;
506     addr = target;
507   } else if (N == 64) {
508     if (UsingAArch32())
509       return false;
510     // TODO: Remove the tag bits from a tagged target
511     addr = target;
512   } else
513     return false;
514 
515   return WriteRegisterUnsigned(context, eRegisterKindGeneric,
516                                LLDB_REGNUM_GENERIC_PC, addr);
517 }
518 
519 bool EmulateInstructionARM64::ConditionHolds(const uint32_t cond) {
520   // If we are ignoring conditions, then always return true. this allows us to
521   // iterate over disassembly code and still emulate an instruction even if we
522   // don't have all the right bits set in the CPSR register...
523   if (m_ignore_conditions)
524     return true;
525 
526   bool result = false;
527   switch (UnsignedBits(cond, 3, 1)) {
528   case 0:
529     result = (m_opcode_pstate.Z == 1);
530     break;
531   case 1:
532     result = (m_opcode_pstate.C == 1);
533     break;
534   case 2:
535     result = (m_opcode_pstate.N == 1);
536     break;
537   case 3:
538     result = (m_opcode_pstate.V == 1);
539     break;
540   case 4:
541     result = (m_opcode_pstate.C == 1 && m_opcode_pstate.Z == 0);
542     break;
543   case 5:
544     result = (m_opcode_pstate.N == m_opcode_pstate.V);
545     break;
546   case 6:
547     result = (m_opcode_pstate.N == m_opcode_pstate.V && m_opcode_pstate.Z == 0);
548     break;
549   case 7:
550     // Always execute (cond == 0b1110, or the special 0b1111 which gives
551     // opcodes different meanings, but always means execution happens.
552     return true;
553   }
554 
555   if (cond & 1)
556     result = !result;
557   return result;
558 }
559 
560 uint64_t EmulateInstructionARM64::
561 AddWithCarry(uint32_t N, uint64_t x, uint64_t y, bit carry_in,
562              EmulateInstructionARM64::ProcState &proc_state) {
563   uint64_t unsigned_sum = UInt(x) + UInt(y) + UInt(carry_in);
564   std::optional<int64_t> signed_sum = llvm::checkedAdd(SInt(x), SInt(y));
565   bool overflow = !signed_sum;
566   if (!overflow)
567     overflow |= !llvm::checkedAdd(*signed_sum, SInt(carry_in));
568   uint64_t result = unsigned_sum;
569   if (N < 64)
570     result = Bits64(result, N - 1, 0);
571   proc_state.N = Bit64(result, N - 1);
572   proc_state.Z = IsZero(result);
573   proc_state.C = UInt(result) != unsigned_sum;
574   proc_state.V = overflow;
575   return result;
576 }
577 
578 bool EmulateInstructionARM64::EmulateADDSUBImm(const uint32_t opcode) {
579   // integer d = UInt(Rd);
580   // integer n = UInt(Rn);
581   // integer datasize = if sf == 1 then 64 else 32;
582   // boolean sub_op = (op == 1);
583   // boolean setflags = (S == 1);
584   // bits(datasize) imm;
585   //
586   // case shift of
587   //     when '00' imm = ZeroExtend(imm12, datasize);
588   //     when '01' imm = ZeroExtend(imm12 : Zeros(12), datasize);
589   //    when '1x' UNDEFINED;
590   //
591   //
592   // bits(datasize) result;
593   // bits(datasize) operand1 = if n == 31 then SP[] else X[n];
594   // bits(datasize) operand2 = imm;
595   // bits(4) nzcv;
596   // bit carry_in;
597   //
598   // if sub_op then
599   //     operand2 = NOT(operand2);
600   //     carry_in = 1;
601   // else
602   //     carry_in = 0;
603   //
604   // (result, nzcv) = AddWithCarry(operand1, operand2, carry_in);
605   //
606   // if setflags then
607   //     PSTATE.NZCV = nzcv;
608   //
609   // if d == 31 && !setflags then
610   //     SP[] = result;
611   // else
612   //     X[d] = result;
613 
614   const uint32_t sf = Bit32(opcode, 31);
615   const uint32_t op = Bit32(opcode, 30);
616   const uint32_t S = Bit32(opcode, 29);
617   const uint32_t shift = Bits32(opcode, 23, 22);
618   const uint32_t imm12 = Bits32(opcode, 21, 10);
619   const uint32_t Rn = Bits32(opcode, 9, 5);
620   const uint32_t Rd = Bits32(opcode, 4, 0);
621 
622   bool success = false;
623 
624   const uint32_t d = UInt(Rd);
625   const uint32_t n = UInt(Rn);
626   const uint32_t datasize = (sf == 1) ? 64 : 32;
627   boolean sub_op = op == 1;
628   boolean setflags = S == 1;
629   uint64_t imm;
630 
631   switch (shift) {
632   case 0:
633     imm = imm12;
634     break;
635   case 1:
636     imm = static_cast<uint64_t>(imm12) << 12;
637     break;
638   default:
639     return false; // UNDEFINED;
640   }
641   uint64_t result;
642   uint64_t operand1 =
643       ReadRegisterUnsigned(eRegisterKindLLDB, gpr_x0_arm64 + n, 0, &success);
644   uint64_t operand2 = imm;
645   bit carry_in;
646 
647   if (sub_op) {
648     operand2 = NOT(operand2);
649     carry_in = true;
650     imm = -imm; // For the Register plug offset context below
651   } else {
652     carry_in = false;
653   }
654 
655   ProcState proc_state;
656 
657   result = AddWithCarry(datasize, operand1, operand2, carry_in, proc_state);
658 
659   if (setflags) {
660     m_emulated_pstate.N = proc_state.N;
661     m_emulated_pstate.Z = proc_state.Z;
662     m_emulated_pstate.C = proc_state.C;
663     m_emulated_pstate.V = proc_state.V;
664   }
665 
666   Context context;
667   std::optional<RegisterInfo> reg_info_Rn =
668       GetRegisterInfo(eRegisterKindLLDB, n);
669   if (reg_info_Rn)
670     context.SetRegisterPlusOffset(*reg_info_Rn, imm);
671 
672   if (n == GetFramePointerRegisterNumber() && d == gpr_sp_arm64 && !setflags) {
673     // 'mov sp, fp' - common epilogue instruction, CFA is now in terms of the
674     // stack pointer, instead of frame pointer.
675     context.type = EmulateInstruction::eContextRestoreStackPointer;
676   } else if ((n == gpr_sp_arm64 || n == GetFramePointerRegisterNumber()) &&
677              d == gpr_sp_arm64 && !setflags) {
678     context.type = EmulateInstruction::eContextAdjustStackPointer;
679   } else if (d == GetFramePointerRegisterNumber() && n == gpr_sp_arm64 &&
680              !setflags) {
681     context.type = EmulateInstruction::eContextSetFramePointer;
682   } else {
683     context.type = EmulateInstruction::eContextImmediate;
684   }
685 
686   // If setflags && d == gpr_sp_arm64 then d = WZR/XZR. See CMN, CMP
687   if (!setflags || d != gpr_sp_arm64)
688     WriteRegisterUnsigned(context, eRegisterKindLLDB, gpr_x0_arm64 + d, result);
689 
690   return false;
691 }
692 
693 template <EmulateInstructionARM64::AddrMode a_mode>
694 bool EmulateInstructionARM64::EmulateLDPSTP(const uint32_t opcode) {
695   uint32_t opc = Bits32(opcode, 31, 30);
696   uint32_t V = Bit32(opcode, 26);
697   uint32_t L = Bit32(opcode, 22);
698   uint32_t imm7 = Bits32(opcode, 21, 15);
699   uint32_t Rt2 = Bits32(opcode, 14, 10);
700   uint32_t Rn = Bits32(opcode, 9, 5);
701   uint32_t Rt = Bits32(opcode, 4, 0);
702 
703   integer n = UInt(Rn);
704   integer t = UInt(Rt);
705   integer t2 = UInt(Rt2);
706   uint64_t idx;
707 
708   MemOp memop = L == 1 ? MemOp_LOAD : MemOp_STORE;
709   boolean vector = (V == 1);
710   // AccType acctype = AccType_NORMAL;
711   boolean is_signed = false;
712   boolean wback = a_mode != AddrMode_OFF;
713   boolean wb_unknown = false;
714   boolean rt_unknown = false;
715   integer scale;
716   integer size;
717 
718   if (opc == 3)
719     return false; // UNDEFINED
720 
721   if (vector) {
722     scale = 2 + UInt(opc);
723   } else {
724     scale = (opc & 2) ? 3 : 2;
725     is_signed = (opc & 1) != 0;
726     if (is_signed && memop == MemOp_STORE)
727       return false; // UNDEFINED
728   }
729 
730   if (!vector && wback && ((t == n) || (t2 == n))) {
731     switch (ConstrainUnpredictable(Unpredictable_WBOVERLAP)) {
732     case Constraint_UNKNOWN:
733       wb_unknown = true; // writeback is UNKNOWN
734       break;
735 
736     case Constraint_SUPPRESSWB:
737       wback = false; // writeback is suppressed
738       break;
739 
740     case Constraint_NOP:
741       memop = MemOp_NOP; // do nothing
742       wback = false;
743       break;
744 
745     case Constraint_NONE:
746       break;
747     }
748   }
749 
750   if (memop == MemOp_LOAD && t == t2) {
751     switch (ConstrainUnpredictable(Unpredictable_LDPOVERLAP)) {
752     case Constraint_UNKNOWN:
753       rt_unknown = true; // result is UNKNOWN
754       break;
755 
756     case Constraint_NOP:
757       memop = MemOp_NOP; // do nothing
758       wback = false;
759       break;
760 
761     default:
762       break;
763     }
764   }
765 
766   idx = LSL(llvm::SignExtend64<7>(imm7), scale);
767   size = (integer)1 << scale;
768   uint64_t datasize = size * 8;
769   uint64_t address;
770   uint64_t wb_address;
771 
772   std::optional<RegisterInfo> reg_info_base =
773       GetRegisterInfo(eRegisterKindLLDB, gpr_x0_arm64 + n);
774   if (!reg_info_base)
775     return false;
776 
777   std::optional<RegisterInfo> reg_info_Rt;
778   std::optional<RegisterInfo> reg_info_Rt2;
779 
780   if (vector) {
781     reg_info_Rt = GetRegisterInfo(eRegisterKindLLDB, fpu_d0_arm64 + t);
782     reg_info_Rt2 = GetRegisterInfo(eRegisterKindLLDB, fpu_d0_arm64 + t2);
783   } else {
784     reg_info_Rt = GetRegisterInfo(eRegisterKindLLDB, gpr_x0_arm64 + t);
785     reg_info_Rt2 = GetRegisterInfo(eRegisterKindLLDB, gpr_x0_arm64 + t2);
786   }
787 
788   if (!reg_info_Rt || !reg_info_Rt2)
789     return false;
790 
791   bool success = false;
792   if (n == 31) {
793     // CheckSPAlignment();
794     address =
795         ReadRegisterUnsigned(eRegisterKindLLDB, gpr_sp_arm64, 0, &success);
796   } else
797     address =
798         ReadRegisterUnsigned(eRegisterKindLLDB, gpr_x0_arm64 + n, 0, &success);
799 
800   wb_address = address + idx;
801   if (a_mode != AddrMode_POST)
802     address = wb_address;
803 
804   Context context_t;
805   Context context_t2;
806 
807   RegisterValue::BytesContainer buffer;
808   Status error;
809 
810   switch (memop) {
811   case MemOp_STORE: {
812     if (n == 31 || n == GetFramePointerRegisterNumber()) // if this store is
813                                                          // based off of the sp
814                                                          // or fp register
815     {
816       context_t.type = eContextPushRegisterOnStack;
817       context_t2.type = eContextPushRegisterOnStack;
818     } else {
819       context_t.type = eContextRegisterStore;
820       context_t2.type = eContextRegisterStore;
821     }
822     context_t.SetRegisterToRegisterPlusOffset(*reg_info_Rt, *reg_info_base, 0);
823     context_t2.SetRegisterToRegisterPlusOffset(*reg_info_Rt2, *reg_info_base,
824                                                size);
825 
826     std::optional<RegisterValue> data_Rt = ReadRegister(*reg_info_Rt);
827     if (!data_Rt)
828       return false;
829 
830     buffer.resize(reg_info_Rt->byte_size);
831     if (data_Rt->GetAsMemoryData(*reg_info_Rt, buffer.data(),
832                                  reg_info_Rt->byte_size, eByteOrderLittle,
833                                  error) == 0)
834       return false;
835 
836     if (!WriteMemory(context_t, address + 0, buffer.data(),
837                      reg_info_Rt->byte_size))
838       return false;
839 
840     std::optional<RegisterValue> data_Rt2 = ReadRegister(*reg_info_Rt2);
841     if (!data_Rt2)
842       return false;
843 
844     buffer.resize(reg_info_Rt2->byte_size);
845     if (data_Rt2->GetAsMemoryData(*reg_info_Rt2, buffer.data(),
846                                   reg_info_Rt2->byte_size, eByteOrderLittle,
847                                   error) == 0)
848       return false;
849 
850     if (!WriteMemory(context_t2, address + size, buffer.data(),
851                      reg_info_Rt2->byte_size))
852       return false;
853   } break;
854 
855   case MemOp_LOAD: {
856     if (n == 31 || n == GetFramePointerRegisterNumber()) // if this load is
857                                                          // based off of the sp
858                                                          // or fp register
859     {
860       context_t.type = eContextPopRegisterOffStack;
861       context_t2.type = eContextPopRegisterOffStack;
862     } else {
863       context_t.type = eContextRegisterLoad;
864       context_t2.type = eContextRegisterLoad;
865     }
866     context_t.SetAddress(address);
867     context_t2.SetAddress(address + size);
868 
869     buffer.resize(reg_info_Rt->byte_size);
870     if (rt_unknown)
871       std::fill(buffer.begin(), buffer.end(), 'U');
872     else {
873       if (!ReadMemory(context_t, address, buffer.data(),
874                       reg_info_Rt->byte_size))
875         return false;
876     }
877 
878     RegisterValue data_Rt;
879     if (data_Rt.SetFromMemoryData(*reg_info_Rt, buffer.data(),
880                                   reg_info_Rt->byte_size, eByteOrderLittle,
881                                   error) == 0)
882       return false;
883 
884     if (!vector && is_signed && !data_Rt.SignExtend(datasize))
885       return false;
886 
887     if (!WriteRegister(context_t, *reg_info_Rt, data_Rt))
888       return false;
889 
890     buffer.resize(reg_info_Rt2->byte_size);
891     if (!rt_unknown)
892       if (!ReadMemory(context_t2, address + size, buffer.data(),
893                       reg_info_Rt2->byte_size))
894         return false;
895 
896     RegisterValue data_Rt2;
897     if (data_Rt2.SetFromMemoryData(*reg_info_Rt2, buffer.data(),
898                                    reg_info_Rt2->byte_size, eByteOrderLittle,
899                                    error) == 0)
900       return false;
901 
902     if (!vector && is_signed && !data_Rt2.SignExtend(datasize))
903       return false;
904 
905     if (!WriteRegister(context_t2, *reg_info_Rt2, data_Rt2))
906       return false;
907   } break;
908 
909   default:
910     break;
911   }
912 
913   if (wback) {
914     if (wb_unknown)
915       wb_address = LLDB_INVALID_ADDRESS;
916     Context context;
917     context.SetImmediateSigned(idx);
918     if (n == 31)
919       context.type = eContextAdjustStackPointer;
920     else
921       context.type = eContextAdjustBaseRegister;
922     WriteRegisterUnsigned(context, *reg_info_base, wb_address);
923   }
924   return true;
925 }
926 
927 template <EmulateInstructionARM64::AddrMode a_mode>
928 bool EmulateInstructionARM64::EmulateLDRSTRImm(const uint32_t opcode) {
929   uint32_t size = Bits32(opcode, 31, 30);
930   uint32_t opc = Bits32(opcode, 23, 22);
931   uint32_t n = Bits32(opcode, 9, 5);
932   uint32_t t = Bits32(opcode, 4, 0);
933 
934   bool wback;
935   bool postindex;
936   uint64_t offset;
937 
938   switch (a_mode) {
939   case AddrMode_POST:
940     wback = true;
941     postindex = true;
942     offset = llvm::SignExtend64<9>(Bits32(opcode, 20, 12));
943     break;
944   case AddrMode_PRE:
945     wback = true;
946     postindex = false;
947     offset = llvm::SignExtend64<9>(Bits32(opcode, 20, 12));
948     break;
949   case AddrMode_OFF:
950     wback = false;
951     postindex = false;
952     offset = LSL(Bits32(opcode, 21, 10), size);
953     break;
954   }
955 
956   MemOp memop;
957 
958   if (Bit32(opc, 1) == 0) {
959     memop = Bit32(opc, 0) == 1 ? MemOp_LOAD : MemOp_STORE;
960   } else {
961     memop = MemOp_LOAD;
962     if (size == 2 && Bit32(opc, 0) == 1)
963       return false;
964   }
965 
966   Status error;
967   bool success = false;
968   uint64_t address;
969   RegisterValue::BytesContainer buffer;
970 
971   if (n == 31)
972     address =
973         ReadRegisterUnsigned(eRegisterKindLLDB, gpr_sp_arm64, 0, &success);
974   else
975     address =
976         ReadRegisterUnsigned(eRegisterKindLLDB, gpr_x0_arm64 + n, 0, &success);
977 
978   if (!success)
979     return false;
980 
981   if (!postindex)
982     address += offset;
983 
984   std::optional<RegisterInfo> reg_info_base =
985       GetRegisterInfo(eRegisterKindLLDB, gpr_x0_arm64 + n);
986   if (!reg_info_base)
987     return false;
988 
989   std::optional<RegisterInfo> reg_info_Rt =
990       GetRegisterInfo(eRegisterKindLLDB, gpr_x0_arm64 + t);
991   if (!reg_info_Rt)
992     return false;
993 
994   Context context;
995   switch (memop) {
996   case MemOp_STORE: {
997     if (n == 31 || n == GetFramePointerRegisterNumber()) // if this store is
998                                                          // based off of the sp
999                                                          // or fp register
1000       context.type = eContextPushRegisterOnStack;
1001     else
1002       context.type = eContextRegisterStore;
1003     context.SetRegisterToRegisterPlusOffset(*reg_info_Rt, *reg_info_base,
1004                                             postindex ? 0 : offset);
1005 
1006     std::optional<RegisterValue> data_Rt = ReadRegister(*reg_info_Rt);
1007     if (!data_Rt)
1008       return false;
1009 
1010     buffer.resize(reg_info_Rt->byte_size);
1011     if (data_Rt->GetAsMemoryData(*reg_info_Rt, buffer.data(),
1012                                  reg_info_Rt->byte_size, eByteOrderLittle,
1013                                  error) == 0)
1014       return false;
1015 
1016     if (!WriteMemory(context, address, buffer.data(), reg_info_Rt->byte_size))
1017       return false;
1018   } break;
1019 
1020   case MemOp_LOAD: {
1021     if (n == 31 || n == GetFramePointerRegisterNumber()) // if this store is
1022                                                          // based off of the sp
1023                                                          // or fp register
1024       context.type = eContextPopRegisterOffStack;
1025     else
1026       context.type = eContextRegisterLoad;
1027     context.SetAddress(address);
1028 
1029     buffer.resize(reg_info_Rt->byte_size);
1030     if (!ReadMemory(context, address, buffer.data(), reg_info_Rt->byte_size))
1031       return false;
1032 
1033     RegisterValue data_Rt;
1034     if (data_Rt.SetFromMemoryData(*reg_info_Rt, buffer.data(),
1035                                   reg_info_Rt->byte_size, eByteOrderLittle,
1036                                   error) == 0)
1037       return false;
1038 
1039     if (!WriteRegister(context, *reg_info_Rt, data_Rt))
1040       return false;
1041   } break;
1042   default:
1043     return false;
1044   }
1045 
1046   if (wback) {
1047     if (postindex)
1048       address += offset;
1049 
1050     if (n == 31)
1051       context.type = eContextAdjustStackPointer;
1052     else
1053       context.type = eContextAdjustBaseRegister;
1054     context.SetImmediateSigned(offset);
1055 
1056     if (!WriteRegisterUnsigned(context, *reg_info_base, address))
1057       return false;
1058   }
1059   return true;
1060 }
1061 
1062 bool EmulateInstructionARM64::EmulateB(const uint32_t opcode) {
1063 #if 0
1064     // ARM64 pseudo code...
1065     if branch_type == BranchType_CALL then X[30] = PC[] + 4;
1066     BranchTo(PC[] + offset, branch_type);
1067 #endif
1068 
1069   bool success = false;
1070 
1071   EmulateInstruction::Context context;
1072   context.type = EmulateInstruction::eContextRelativeBranchImmediate;
1073   const uint64_t pc = ReadRegisterUnsigned(eRegisterKindGeneric,
1074                                            LLDB_REGNUM_GENERIC_PC, 0, &success);
1075   if (!success)
1076     return false;
1077 
1078   int64_t offset = llvm::SignExtend64<28>(Bits32(opcode, 25, 0) << 2);
1079   BranchType branch_type = Bit32(opcode, 31) ? BranchType_CALL : BranchType_JMP;
1080   addr_t target = pc + offset;
1081   context.SetImmediateSigned(offset);
1082 
1083   switch (branch_type) {
1084   case BranchType_CALL: {
1085     addr_t x30 = pc + 4;
1086     if (!WriteRegisterUnsigned(context, eRegisterKindLLDB, gpr_lr_arm64, x30))
1087       return false;
1088   } break;
1089   case BranchType_JMP:
1090     break;
1091   default:
1092     return false;
1093   }
1094 
1095   return BranchTo(context, 64, target);
1096 }
1097 
1098 bool EmulateInstructionARM64::EmulateBcond(const uint32_t opcode) {
1099 #if 0
1100     // ARM64 pseudo code...
1101     bits(64) offset = SignExtend(imm19:'00', 64);
1102     bits(4) condition = cond;
1103     if ConditionHolds(condition) then
1104         BranchTo(PC[] + offset, BranchType_JMP);
1105 #endif
1106 
1107   if (ConditionHolds(Bits32(opcode, 3, 0))) {
1108     bool success = false;
1109 
1110     const uint64_t pc = ReadRegisterUnsigned(
1111         eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, 0, &success);
1112     if (!success)
1113       return false;
1114 
1115     int64_t offset = llvm::SignExtend64<21>(Bits32(opcode, 23, 5) << 2);
1116     addr_t target = pc + offset;
1117 
1118     EmulateInstruction::Context context;
1119     context.type = EmulateInstruction::eContextRelativeBranchImmediate;
1120     context.SetImmediateSigned(offset);
1121     if (!BranchTo(context, 64, target))
1122       return false;
1123   }
1124   return true;
1125 }
1126 
1127 bool EmulateInstructionARM64::EmulateCBZ(const uint32_t opcode) {
1128 #if 0
1129     integer t = UInt(Rt);
1130     integer datasize = if sf == '1' then 64 else 32;
1131     boolean iszero = (op == '0');
1132     bits(64) offset = SignExtend(imm19:'00', 64);
1133 
1134     bits(datasize) operand1 = X[t];
1135     if IsZero(operand1) == iszero then
1136         BranchTo(PC[] + offset, BranchType_JMP);
1137 #endif
1138 
1139   bool success = false;
1140 
1141   uint32_t t = Bits32(opcode, 4, 0);
1142   bool is_zero = Bit32(opcode, 24) == 0;
1143   int32_t offset = llvm::SignExtend64<21>(Bits32(opcode, 23, 5) << 2);
1144 
1145   const uint64_t operand =
1146       ReadRegisterUnsigned(eRegisterKindLLDB, gpr_x0_arm64 + t, 0, &success);
1147   if (!success)
1148     return false;
1149 
1150   if (m_ignore_conditions || ((operand == 0) == is_zero)) {
1151     const uint64_t pc = ReadRegisterUnsigned(
1152         eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, 0, &success);
1153     if (!success)
1154       return false;
1155 
1156     EmulateInstruction::Context context;
1157     context.type = EmulateInstruction::eContextRelativeBranchImmediate;
1158     context.SetImmediateSigned(offset);
1159     if (!BranchTo(context, 64, pc + offset))
1160       return false;
1161   }
1162   return true;
1163 }
1164 
1165 bool EmulateInstructionARM64::EmulateTBZ(const uint32_t opcode) {
1166 #if 0
1167     integer t = UInt(Rt);
1168     integer datasize = if b5 == '1' then 64 else 32;
1169     integer bit_pos = UInt(b5:b40);
1170     bit bit_val = op;
1171     bits(64) offset = SignExtend(imm14:'00', 64);
1172 #endif
1173 
1174   bool success = false;
1175 
1176   uint32_t t = Bits32(opcode, 4, 0);
1177   uint32_t bit_pos = (Bit32(opcode, 31) << 6) | (Bits32(opcode, 23, 19));
1178   uint32_t bit_val = Bit32(opcode, 24);
1179   int64_t offset = llvm::SignExtend64<16>(Bits32(opcode, 18, 5) << 2);
1180 
1181   const uint64_t operand =
1182       ReadRegisterUnsigned(eRegisterKindLLDB, gpr_x0_arm64 + t, 0, &success);
1183   if (!success)
1184     return false;
1185 
1186   if (m_ignore_conditions || Bit32(operand, bit_pos) == bit_val) {
1187     const uint64_t pc = ReadRegisterUnsigned(
1188         eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, 0, &success);
1189     if (!success)
1190       return false;
1191 
1192     EmulateInstruction::Context context;
1193     context.type = EmulateInstruction::eContextRelativeBranchImmediate;
1194     context.SetImmediateSigned(offset);
1195     if (!BranchTo(context, 64, pc + offset))
1196       return false;
1197   }
1198   return true;
1199 }
1200