1	//===-- DWARFExpression.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 "lldb/Expression/DWARFExpression.h"
10
11	#include <cinttypes>
12
13	#include <optional>
14	#include <vector>
15
16	#include "lldb/Core/Module.h"
17	#include "lldb/Core/Value.h"
18	#include "lldb/Utility/DataEncoder.h"
19	#include "lldb/Utility/LLDBLog.h"
20	#include "lldb/Utility/Log.h"
21	#include "lldb/Utility/RegisterValue.h"
22	#include "lldb/Utility/Scalar.h"
23	#include "lldb/Utility/StreamString.h"
24	#include "lldb/Utility/VMRange.h"
25
26	#include "lldb/Host/Host.h"
27	#include "lldb/Utility/Endian.h"
28
29	#include "lldb/Symbol/Function.h"
30
31	#include "lldb/Target/ABI.h"
32	#include "lldb/Target/ExecutionContext.h"
33	#include "lldb/Target/Process.h"
34	#include "lldb/Target/RegisterContext.h"
35	#include "lldb/Target/StackFrame.h"
36	#include "lldb/Target/StackID.h"
37	#include "lldb/Target/Target.h"
38	#include "lldb/Target/Thread.h"
39	#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
40
41	using namespace lldb;
42	using namespace lldb_private;
43	using namespace lldb_private::dwarf;
44	using namespace lldb_private::plugin::dwarf;
45
46	// DWARFExpression constructor
47	DWARFExpression::DWARFExpression() : m_data() {}
48
49	DWARFExpression::DWARFExpression(const DataExtractor &data) : m_data(data) {}
50
51	// Destructor
52	DWARFExpression::~DWARFExpression() = default;
53
54	bool DWARFExpression::IsValid() const { return m_data.GetByteSize() > 0; }
55
56	void DWARFExpression::UpdateValue(uint64_t const_value,
57	lldb::offset_t const_value_byte_size,
58	uint8_t addr_byte_size) {
59	if (!const_value_byte_size)
60	return;
61
62	m_data.SetData(
63	data_sp: DataBufferSP(new DataBufferHeap(&const_value, const_value_byte_size)));
64	m_data.SetByteOrder(endian::InlHostByteOrder());
65	m_data.SetAddressByteSize(addr_byte_size);
66	}
67
68	void DWARFExpression::DumpLocation(Stream *s, lldb::DescriptionLevel level,
69	ABI *abi) const {
70	auto *MCRegInfo = abi ? &abi->GetMCRegisterInfo() : nullptr;
71	auto GetRegName = [&MCRegInfo](uint64_t DwarfRegNum,
72	bool IsEH) -> llvm::StringRef {
73	if (!MCRegInfo)
74	return {};
75	if (std::optional<unsigned> LLVMRegNum =
76	MCRegInfo->getLLVMRegNum(RegNum: DwarfRegNum, isEH: IsEH))
77	if (const char *RegName = MCRegInfo->getName(RegNo: *LLVMRegNum))
78	return llvm::StringRef(RegName);
79	return {};
80	};
81	llvm::DIDumpOptions DumpOpts;
82	DumpOpts.GetNameForDWARFReg = GetRegName;
83	llvm::DWARFExpression E(m_data.GetAsLLVM(), m_data.GetAddressByteSize());
84	llvm::DWARFExpressionPrinter::print(E: &E, OS&: s->AsRawOstream(), DumpOpts, U: nullptr);
85	}
86
87	RegisterKind DWARFExpression::GetRegisterKind() const { return m_reg_kind; }
88
89	void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
90	m_reg_kind = reg_kind;
91	}
92
93	static llvm::Error ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
94	lldb::RegisterKind reg_kind,
95	uint32_t reg_num, Value &value) {
96	if (reg_ctx == nullptr)
97	return llvm::createStringError(Fmt: "no register context in frame");
98
99	const uint32_t native_reg =
100	reg_ctx->ConvertRegisterKindToRegisterNumber(kind: reg_kind, num: reg_num);
101	if (native_reg == LLDB_INVALID_REGNUM)
102	return llvm::createStringError(
103	Fmt: "unable to convert register kind=%u reg_num=%u to a native "
104	"register number",
105	Vals: reg_kind, Vals: reg_num);
106
107	const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(reg: native_reg);
108	RegisterValue reg_value;
109	if (reg_ctx->ReadRegister(reg_info, reg_value)) {
110	if (reg_value.GetScalarValue(scalar&: value.GetScalar())) {
111	value.SetValueType(Value::ValueType::Scalar);
112	value.SetContext(context_type: Value::ContextType::RegisterInfo,
113	p: const_cast<RegisterInfo *>(reg_info));
114	return llvm::Error::success();
115	}
116
117	// If we get this error, then we need to implement a value buffer in
118	// the dwarf expression evaluation function...
119	return llvm::createStringError(
120	Fmt: "register %s can't be converted to a scalar value", Vals: reg_info->name);
121	}
122
123	return llvm::createStringError(Fmt: "register %s is not available",
124	Vals: reg_info->name);
125	}
126
127	/// Return the length in bytes of the set of operands for \p op. No guarantees
128	/// are made on the state of \p data after this call.
129	static lldb::offset_t
130	GetOpcodeDataSize(const DataExtractor &data, const lldb::offset_t data_offset,
131	const LocationAtom op,
132	const DWARFExpression::Delegate *dwarf_cu) {
133	lldb::offset_t offset = data_offset;
134	switch (op) {
135	// Only used in LLVM metadata.
136	case DW_OP_LLVM_fragment:
137	case DW_OP_LLVM_convert:
138	case DW_OP_LLVM_tag_offset:
139	case DW_OP_LLVM_entry_value:
140	case DW_OP_LLVM_implicit_pointer:
141	case DW_OP_LLVM_arg:
142	case DW_OP_LLVM_extract_bits_sext:
143	case DW_OP_LLVM_extract_bits_zext:
144	break;
145	// Vendor extensions:
146	case DW_OP_HP_is_value:
147	case DW_OP_HP_fltconst4:
148	case DW_OP_HP_fltconst8:
149	case DW_OP_HP_mod_range:
150	case DW_OP_HP_unmod_range:
151	case DW_OP_HP_tls:
152	case DW_OP_INTEL_bit_piece:
153	case DW_OP_WASM_location:
154	case DW_OP_WASM_location_int:
155	case DW_OP_APPLE_uninit:
156	case DW_OP_PGI_omp_thread_num:
157	case DW_OP_hi_user:
158	case DW_OP_GNU_implicit_pointer:
159	break;
160
161	case DW_OP_addr:
162	case DW_OP_call_ref: // 0x9a 1 address sized offset of DIE (DWARF3)
163	return data.GetAddressByteSize();
164
165	// Opcodes with no arguments
166	case DW_OP_deref: // 0x06
167	case DW_OP_dup: // 0x12
168	case DW_OP_drop: // 0x13
169	case DW_OP_over: // 0x14
170	case DW_OP_swap: // 0x16
171	case DW_OP_rot: // 0x17
172	case DW_OP_xderef: // 0x18
173	case DW_OP_abs: // 0x19
174	case DW_OP_and: // 0x1a
175	case DW_OP_div: // 0x1b
176	case DW_OP_minus: // 0x1c
177	case DW_OP_mod: // 0x1d
178	case DW_OP_mul: // 0x1e
179	case DW_OP_neg: // 0x1f
180	case DW_OP_not: // 0x20
181	case DW_OP_or: // 0x21
182	case DW_OP_plus: // 0x22
183	case DW_OP_shl: // 0x24
184	case DW_OP_shr: // 0x25
185	case DW_OP_shra: // 0x26
186	case DW_OP_xor: // 0x27
187	case DW_OP_eq: // 0x29
188	case DW_OP_ge: // 0x2a
189	case DW_OP_gt: // 0x2b
190	case DW_OP_le: // 0x2c
191	case DW_OP_lt: // 0x2d
192	case DW_OP_ne: // 0x2e
193	case DW_OP_lit0: // 0x30
194	case DW_OP_lit1: // 0x31
195	case DW_OP_lit2: // 0x32
196	case DW_OP_lit3: // 0x33
197	case DW_OP_lit4: // 0x34
198	case DW_OP_lit5: // 0x35
199	case DW_OP_lit6: // 0x36
200	case DW_OP_lit7: // 0x37
201	case DW_OP_lit8: // 0x38
202	case DW_OP_lit9: // 0x39
203	case DW_OP_lit10: // 0x3A
204	case DW_OP_lit11: // 0x3B
205	case DW_OP_lit12: // 0x3C
206	case DW_OP_lit13: // 0x3D
207	case DW_OP_lit14: // 0x3E
208	case DW_OP_lit15: // 0x3F
209	case DW_OP_lit16: // 0x40
210	case DW_OP_lit17: // 0x41
211	case DW_OP_lit18: // 0x42
212	case DW_OP_lit19: // 0x43
213	case DW_OP_lit20: // 0x44
214	case DW_OP_lit21: // 0x45
215	case DW_OP_lit22: // 0x46
216	case DW_OP_lit23: // 0x47
217	case DW_OP_lit24: // 0x48
218	case DW_OP_lit25: // 0x49
219	case DW_OP_lit26: // 0x4A
220	case DW_OP_lit27: // 0x4B
221	case DW_OP_lit28: // 0x4C
222	case DW_OP_lit29: // 0x4D
223	case DW_OP_lit30: // 0x4E
224	case DW_OP_lit31: // 0x4f
225	case DW_OP_reg0: // 0x50
226	case DW_OP_reg1: // 0x51
227	case DW_OP_reg2: // 0x52
228	case DW_OP_reg3: // 0x53
229	case DW_OP_reg4: // 0x54
230	case DW_OP_reg5: // 0x55
231	case DW_OP_reg6: // 0x56
232	case DW_OP_reg7: // 0x57
233	case DW_OP_reg8: // 0x58
234	case DW_OP_reg9: // 0x59
235	case DW_OP_reg10: // 0x5A
236	case DW_OP_reg11: // 0x5B
237	case DW_OP_reg12: // 0x5C
238	case DW_OP_reg13: // 0x5D
239	case DW_OP_reg14: // 0x5E
240	case DW_OP_reg15: // 0x5F
241	case DW_OP_reg16: // 0x60
242	case DW_OP_reg17: // 0x61
243	case DW_OP_reg18: // 0x62
244	case DW_OP_reg19: // 0x63
245	case DW_OP_reg20: // 0x64
246	case DW_OP_reg21: // 0x65
247	case DW_OP_reg22: // 0x66
248	case DW_OP_reg23: // 0x67
249	case DW_OP_reg24: // 0x68
250	case DW_OP_reg25: // 0x69
251	case DW_OP_reg26: // 0x6A
252	case DW_OP_reg27: // 0x6B
253	case DW_OP_reg28: // 0x6C
254	case DW_OP_reg29: // 0x6D
255	case DW_OP_reg30: // 0x6E
256	case DW_OP_reg31: // 0x6F
257	case DW_OP_nop: // 0x96
258	case DW_OP_push_object_address: // 0x97 DWARF3
259	case DW_OP_form_tls_address: // 0x9b DWARF3
260	case DW_OP_call_frame_cfa: // 0x9c DWARF3
261	case DW_OP_stack_value: // 0x9f DWARF4
262	case DW_OP_GNU_push_tls_address: // 0xe0 GNU extension
263	return 0;
264
265	// Opcodes with a single 1 byte arguments
266	case DW_OP_const1u: // 0x08 1 1-byte constant
267	case DW_OP_const1s: // 0x09 1 1-byte constant
268	case DW_OP_pick: // 0x15 1 1-byte stack index
269	case DW_OP_deref_size: // 0x94 1 1-byte size of data retrieved
270	case DW_OP_xderef_size: // 0x95 1 1-byte size of data retrieved
271	case DW_OP_deref_type: // 0xa6 1 1-byte constant
272	return 1;
273
274	// Opcodes with a single 2 byte arguments
275	case DW_OP_const2u: // 0x0a 1 2-byte constant
276	case DW_OP_const2s: // 0x0b 1 2-byte constant
277	case DW_OP_skip: // 0x2f 1 signed 2-byte constant
278	case DW_OP_bra: // 0x28 1 signed 2-byte constant
279	case DW_OP_call2: // 0x98 1 2-byte offset of DIE (DWARF3)
280	return 2;
281
282	// Opcodes with a single 4 byte arguments
283	case DW_OP_const4u: // 0x0c 1 4-byte constant
284	case DW_OP_const4s: // 0x0d 1 4-byte constant
285	case DW_OP_call4: // 0x99 1 4-byte offset of DIE (DWARF3)
286	return 4;
287
288	// Opcodes with a single 8 byte arguments
289	case DW_OP_const8u: // 0x0e 1 8-byte constant
290	case DW_OP_const8s: // 0x0f 1 8-byte constant
291	return 8;
292
293	// All opcodes that have a single ULEB (signed or unsigned) argument
294	case DW_OP_constu: // 0x10 1 ULEB128 constant
295	case DW_OP_consts: // 0x11 1 SLEB128 constant
296	case DW_OP_plus_uconst: // 0x23 1 ULEB128 addend
297	case DW_OP_breg0: // 0x70 1 ULEB128 register
298	case DW_OP_breg1: // 0x71 1 ULEB128 register
299	case DW_OP_breg2: // 0x72 1 ULEB128 register
300	case DW_OP_breg3: // 0x73 1 ULEB128 register
301	case DW_OP_breg4: // 0x74 1 ULEB128 register
302	case DW_OP_breg5: // 0x75 1 ULEB128 register
303	case DW_OP_breg6: // 0x76 1 ULEB128 register
304	case DW_OP_breg7: // 0x77 1 ULEB128 register
305	case DW_OP_breg8: // 0x78 1 ULEB128 register
306	case DW_OP_breg9: // 0x79 1 ULEB128 register
307	case DW_OP_breg10: // 0x7a 1 ULEB128 register
308	case DW_OP_breg11: // 0x7b 1 ULEB128 register
309	case DW_OP_breg12: // 0x7c 1 ULEB128 register
310	case DW_OP_breg13: // 0x7d 1 ULEB128 register
311	case DW_OP_breg14: // 0x7e 1 ULEB128 register
312	case DW_OP_breg15: // 0x7f 1 ULEB128 register
313	case DW_OP_breg16: // 0x80 1 ULEB128 register
314	case DW_OP_breg17: // 0x81 1 ULEB128 register
315	case DW_OP_breg18: // 0x82 1 ULEB128 register
316	case DW_OP_breg19: // 0x83 1 ULEB128 register
317	case DW_OP_breg20: // 0x84 1 ULEB128 register
318	case DW_OP_breg21: // 0x85 1 ULEB128 register
319	case DW_OP_breg22: // 0x86 1 ULEB128 register
320	case DW_OP_breg23: // 0x87 1 ULEB128 register
321	case DW_OP_breg24: // 0x88 1 ULEB128 register
322	case DW_OP_breg25: // 0x89 1 ULEB128 register
323	case DW_OP_breg26: // 0x8a 1 ULEB128 register
324	case DW_OP_breg27: // 0x8b 1 ULEB128 register
325	case DW_OP_breg28: // 0x8c 1 ULEB128 register
326	case DW_OP_breg29: // 0x8d 1 ULEB128 register
327	case DW_OP_breg30: // 0x8e 1 ULEB128 register
328	case DW_OP_breg31: // 0x8f 1 ULEB128 register
329	case DW_OP_regx: // 0x90 1 ULEB128 register
330	case DW_OP_fbreg: // 0x91 1 SLEB128 offset
331	case DW_OP_piece: // 0x93 1 ULEB128 size of piece addressed
332	case DW_OP_convert: // 0xa8 1 ULEB128 offset
333	case DW_OP_reinterpret: // 0xa9 1 ULEB128 offset
334	case DW_OP_addrx: // 0xa1 1 ULEB128 index
335	case DW_OP_constx: // 0xa2 1 ULEB128 index
336	case DW_OP_xderef_type: // 0xa7 1 ULEB128 index
337	case DW_OP_GNU_addr_index: // 0xfb 1 ULEB128 index
338	case DW_OP_GNU_const_index: // 0xfc 1 ULEB128 index
339	data.Skip_LEB128(offset_ptr: &offset);
340	return offset - data_offset;
341
342	// All opcodes that have a 2 ULEB (signed or unsigned) arguments
343	case DW_OP_bregx: // 0x92 2 ULEB128 register followed by SLEB128 offset
344	case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
345	case DW_OP_regval_type: // 0xa5 ULEB128 + ULEB128
346	data.Skip_LEB128(offset_ptr: &offset);
347	data.Skip_LEB128(offset_ptr: &offset);
348	return offset - data_offset;
349
350	case DW_OP_implicit_value: // 0x9e ULEB128 size followed by block of that size
351	// (DWARF4)
352	{
353	uint64_t block_len = data.Skip_LEB128(offset_ptr: &offset);
354	offset += block_len;
355	return offset - data_offset;
356	}
357
358	case DW_OP_implicit_pointer: // 0xa0 4-byte (or 8-byte for DWARF 64) constant
359	// + LEB128
360	{
361	data.Skip_LEB128(offset_ptr: &offset);
362	return (dwarf_cu ? dwarf_cu->GetAddressByteSize() : 4) + offset -
363	data_offset;
364	}
365
366	case DW_OP_GNU_entry_value:
367	case DW_OP_entry_value: // 0xa3 ULEB128 size + variable-length block
368	{
369	uint64_t subexpr_len = data.GetULEB128(offset_ptr: &offset);
370	return (offset - data_offset) + subexpr_len;
371	}
372
373	case DW_OP_const_type: // 0xa4 ULEB128 + size + variable-length block
374	{
375	data.Skip_LEB128(offset_ptr: &offset);
376	uint8_t length = data.GetU8(offset_ptr: &offset);
377	return (offset - data_offset) + length;
378	}
379
380	case DW_OP_LLVM_user: // 0xe9: ULEB128 + variable length constant
381	{
382	uint64_t constants = data.GetULEB128(offset_ptr: &offset);
383	return (offset - data_offset) + constants;
384	}
385	}
386
387	if (dwarf_cu)
388	return dwarf_cu->GetVendorDWARFOpcodeSize(data, data_offset, op);
389
390	return LLDB_INVALID_OFFSET;
391	}
392
393	static const char *DW_OP_value_to_name(uint32_t val) {
394	static char invalid[100];
395	llvm::StringRef llvmstr = llvm::dwarf::OperationEncodingString(Encoding: val);
396	if (llvmstr.empty()) {
397	snprintf(s: invalid, maxlen: sizeof(invalid), format: "Unknown DW_OP constant: 0x%x", val);
398	return invalid;
399	}
400	return llvmstr.data();
401	}
402
403	llvm::Expected<lldb::addr_t> DWARFExpression::GetLocation_DW_OP_addr(
404	const DWARFExpression::Delegate *dwarf_cu) const {
405	lldb::offset_t offset = 0;
406	while (m_data.ValidOffset(offset)) {
407	const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(offset_ptr: &offset));
408
409	if (op == DW_OP_addr)
410	return m_data.GetAddress(offset_ptr: &offset);
411
412	if (op == DW_OP_GNU_addr_index || op == DW_OP_addrx) {
413	const uint64_t index = m_data.GetULEB128(offset_ptr: &offset);
414	if (dwarf_cu)
415	return dwarf_cu->ReadAddressFromDebugAddrSection(index);
416	return llvm::createStringError(Fmt: "cannot evaluate %s without a DWARF unit",
417	Vals: DW_OP_value_to_name(val: op));
418	}
419
420	const lldb::offset_t op_arg_size =
421	GetOpcodeDataSize(data: m_data, data_offset: offset, op, dwarf_cu);
422	if (op_arg_size == LLDB_INVALID_OFFSET)
423	return llvm::createStringError(Fmt: "cannot get opcode data size for %s",
424	Vals: DW_OP_value_to_name(val: op));
425
426	offset += op_arg_size;
427	}
428
429	return LLDB_INVALID_ADDRESS;
430	}
431
432	bool DWARFExpression::Update_DW_OP_addr(
433	const DWARFExpression::Delegate *dwarf_cu, lldb::addr_t file_addr) {
434	lldb::offset_t offset = 0;
435	while (m_data.ValidOffset(offset)) {
436	const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(offset_ptr: &offset));
437
438	if (op == DW_OP_addr) {
439	const uint32_t addr_byte_size = m_data.GetAddressByteSize();
440	// We have to make a copy of the data as we don't know if this data is
441	// from a read only memory mapped buffer, so we duplicate all of the data
442	// first, then modify it, and if all goes well, we then replace the data
443	// for this expression
444
445	// Make en encoder that contains a copy of the location expression data
446	// so we can write the address into the buffer using the correct byte
447	// order.
448	DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(),
449	m_data.GetByteOrder(), addr_byte_size);
450
451	// Replace the address in the new buffer
452	if (encoder.PutAddress(offset, addr: file_addr) == UINT32_MAX)
453	return false;
454
455	// All went well, so now we can reset the data using a shared pointer to
456	// the heap data so "m_data" will now correctly manage the heap data.
457	m_data.SetData(data_sp: encoder.GetDataBuffer());
458	return true;
459	}
460	if (op == DW_OP_addrx) {
461	// Replace DW_OP_addrx with DW_OP_addr, since we can't modify the
462	// read-only debug_addr table.
463	// Subtract one to account for the opcode.
464	llvm::ArrayRef data_before_op = m_data.GetData().take_front(N: offset - 1);
465
466	// Read the addrx index to determine how many bytes it needs.
467	const lldb::offset_t old_offset = offset;
468	m_data.GetULEB128(offset_ptr: &offset);
469	if (old_offset == offset)
470	return false;
471	llvm::ArrayRef data_after_op = m_data.GetData().drop_front(N: offset);
472
473	DataEncoder encoder(m_data.GetByteOrder(), m_data.GetAddressByteSize());
474	encoder.AppendData(data: data_before_op);
475	encoder.AppendU8(value: DW_OP_addr);
476	encoder.AppendAddress(addr: file_addr);
477	encoder.AppendData(data: data_after_op);
478	m_data.SetData(data_sp: encoder.GetDataBuffer());
479	return true;
480	}
481	const lldb::offset_t op_arg_size =
482	GetOpcodeDataSize(data: m_data, data_offset: offset, op, dwarf_cu);
483	if (op_arg_size == LLDB_INVALID_OFFSET)
484	break;
485	offset += op_arg_size;
486	}
487	return false;
488	}
489
490	bool DWARFExpression::ContainsThreadLocalStorage(
491	const DWARFExpression::Delegate *dwarf_cu) const {
492	lldb::offset_t offset = 0;
493	while (m_data.ValidOffset(offset)) {
494	const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(offset_ptr: &offset));
495
496	if (op == DW_OP_form_tls_address || op == DW_OP_GNU_push_tls_address)
497	return true;
498	const lldb::offset_t op_arg_size =
499	GetOpcodeDataSize(data: m_data, data_offset: offset, op, dwarf_cu);
500	if (op_arg_size == LLDB_INVALID_OFFSET)
501	return false;
502	offset += op_arg_size;
503	}
504	return false;
505	}
506	bool DWARFExpression::LinkThreadLocalStorage(
507	const DWARFExpression::Delegate *dwarf_cu,
508	std::function<lldb::addr_t(lldb::addr_t file_addr)> const
509	&link_address_callback) {
510	const uint32_t addr_byte_size = m_data.GetAddressByteSize();
511	// We have to make a copy of the data as we don't know if this data is from a
512	// read only memory mapped buffer, so we duplicate all of the data first,
513	// then modify it, and if all goes well, we then replace the data for this
514	// expression.
515	// Make en encoder that contains a copy of the location expression data so we
516	// can write the address into the buffer using the correct byte order.
517	DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(),
518	m_data.GetByteOrder(), addr_byte_size);
519
520	lldb::offset_t offset = 0;
521	lldb::offset_t const_offset = 0;
522	lldb::addr_t const_value = 0;
523	size_t const_byte_size = 0;
524	while (m_data.ValidOffset(offset)) {
525	const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(offset_ptr: &offset));
526
527	bool decoded_data = false;
528	switch (op) {
529	case DW_OP_const4u:
530	// Remember the const offset in case we later have a
531	// DW_OP_form_tls_address or DW_OP_GNU_push_tls_address
532	const_offset = offset;
533	const_value = m_data.GetU32(offset_ptr: &offset);
534	decoded_data = true;
535	const_byte_size = 4;
536	break;
537
538	case DW_OP_const8u:
539	// Remember the const offset in case we later have a
540	// DW_OP_form_tls_address or DW_OP_GNU_push_tls_address
541	const_offset = offset;
542	const_value = m_data.GetU64(offset_ptr: &offset);
543	decoded_data = true;
544	const_byte_size = 8;
545	break;
546
547	case DW_OP_form_tls_address:
548	case DW_OP_GNU_push_tls_address:
549	// DW_OP_form_tls_address and DW_OP_GNU_push_tls_address must be preceded
550	// by a file address on the stack. We assume that DW_OP_const4u or
551	// DW_OP_const8u is used for these values, and we check that the last
552	// opcode we got before either of these was DW_OP_const4u or
553	// DW_OP_const8u. If so, then we can link the value accordingly. For
554	// Darwin, the value in the DW_OP_const4u or DW_OP_const8u is the file
555	// address of a structure that contains a function pointer, the pthread
556	// key and the offset into the data pointed to by the pthread key. So we
557	// must link this address and also set the module of this expression to
558	// the new_module_sp so we can resolve the file address correctly
559	if (const_byte_size > 0) {
560	lldb::addr_t linked_file_addr = link_address_callback(const_value);
561	if (linked_file_addr == LLDB_INVALID_ADDRESS)
562	return false;
563	// Replace the address in the new buffer
564	if (encoder.PutUnsigned(offset: const_offset, byte_size: const_byte_size,
565	value: linked_file_addr) == UINT32_MAX)
566	return false;
567	}
568	break;
569
570	default:
571	const_offset = 0;
572	const_value = 0;
573	const_byte_size = 0;
574	break;
575	}
576
577	if (!decoded_data) {
578	const lldb::offset_t op_arg_size =
579	GetOpcodeDataSize(data: m_data, data_offset: offset, op, dwarf_cu);
580	if (op_arg_size == LLDB_INVALID_OFFSET)
581	return false;
582	else
583	offset += op_arg_size;
584	}
585	}
586
587	m_data.SetData(data_sp: encoder.GetDataBuffer());
588	return true;
589	}
590
591	static llvm::Error Evaluate_DW_OP_entry_value(std::vector<Value> &stack,
592	ExecutionContext *exe_ctx,
593	RegisterContext *reg_ctx,
594	const DataExtractor &opcodes,
595	lldb::offset_t &opcode_offset,
596	Log *log) {
597	// DW_OP_entry_value(sub-expr) describes the location a variable had upon
598	// function entry: this variable location is presumed to be optimized out at
599	// the current PC value. The caller of the function may have call site
600	// information that describes an alternate location for the variable (e.g. a
601	// constant literal, or a spilled stack value) in the parent frame.
602	//
603	// Example (this is pseudo-code & pseudo-DWARF, but hopefully illustrative):
604	//
605	// void child(int &sink, int x) {
606	// ...
607	// /* "x" gets optimized out. */
608	//
609	// /* The location of "x" here is: DW_OP_entry_value($reg2). */
610	// ++sink;
611	// }
612	//
613	// void parent() {
614	// int sink;
615	//
616	// /*
617	// * The callsite information emitted here is:
618	// *
619	// * DW_TAG_call_site
620	// * DW_AT_return_pc ... (for "child(sink, 123);")
621	// * DW_TAG_call_site_parameter (for "sink")
622	// * DW_AT_location ($reg1)
623	// * DW_AT_call_value ($SP - 8)
624	// * DW_TAG_call_site_parameter (for "x")
625	// * DW_AT_location ($reg2)
626	// * DW_AT_call_value ($literal 123)
627	// *
628	// * DW_TAG_call_site
629	// * DW_AT_return_pc ... (for "child(sink, 456);")
630	// * ...
631	// */
632	// child(sink, 123);
633	// child(sink, 456);
634	// }
635	//
636	// When the program stops at "++sink" within `child`, the debugger determines
637	// the call site by analyzing the return address. Once the call site is found,
638	// the debugger determines which parameter is referenced by DW_OP_entry_value
639	// and evaluates the corresponding location for that parameter in `parent`.
640
641	// 1. Find the function which pushed the current frame onto the stack.
642	if ((!exe_ctx || !exe_ctx->HasTargetScope()) || !reg_ctx) {
643	return llvm::createStringError(Fmt: "no exe/reg context");
644	}
645
646	StackFrame *current_frame = exe_ctx->GetFramePtr();
647	Thread *thread = exe_ctx->GetThreadPtr();
648	if (!current_frame || !thread)
649	return llvm::createStringError(Fmt: "no current frame/thread");
650
651	Target &target = exe_ctx->GetTargetRef();
652	StackFrameSP parent_frame = nullptr;
653	addr_t return_pc = LLDB_INVALID_ADDRESS;
654	uint32_t current_frame_idx = current_frame->GetFrameIndex();
655
656	for (uint32_t parent_frame_idx = current_frame_idx + 1;;parent_frame_idx++) {
657	parent_frame = thread->GetStackFrameAtIndex(idx: parent_frame_idx);
658	// If this is null, we're at the end of the stack.
659	if (!parent_frame)
660	break;
661
662	// Record the first valid return address, even if this is an inlined frame,
663	// in order to look up the associated call edge in the first non-inlined
664	// parent frame.
665	if (return_pc == LLDB_INVALID_ADDRESS) {
666	return_pc = parent_frame->GetFrameCodeAddress().GetLoadAddress(target: &target);
667	LLDB_LOG(log, "immediate ancestor with pc = {0:x}", return_pc);
668	}
669
670	// If we've found an inlined frame, skip it (these have no call site
671	// parameters).
672	if (parent_frame->IsInlined())
673	continue;
674
675	// We've found the first non-inlined parent frame.
676	break;
677	}
678	if (!parent_frame || !parent_frame->GetRegisterContext()) {
679	return llvm::createStringError(Fmt: "no parent frame with reg ctx");
680	}
681
682	Function *parent_func =
683	parent_frame->GetSymbolContext(resolve_scope: eSymbolContextFunction).function;
684	if (!parent_func)
685	return llvm::createStringError(Fmt: "no parent function");
686
687	// 2. Find the call edge in the parent function responsible for creating the
688	// current activation.
689	Function *current_func =
690	current_frame->GetSymbolContext(resolve_scope: eSymbolContextFunction).function;
691	if (!current_func)
692	return llvm::createStringError(Fmt: "no current function");
693
694	CallEdge *call_edge = nullptr;
695	ModuleList &modlist = target.GetImages();
696	ExecutionContext parent_exe_ctx = *exe_ctx;
697	parent_exe_ctx.SetFrameSP(parent_frame);
698	if (!parent_frame->IsArtificial()) {
699	// If the parent frame is not artificial, the current activation may be
700	// produced by an ambiguous tail call. In this case, refuse to proceed.
701	call_edge = parent_func->GetCallEdgeForReturnAddress(return_pc, target);
702	if (!call_edge) {
703	return llvm::createStringError(
704	S: llvm::formatv(Fmt: "no call edge for retn-pc = {0:x} in parent frame {1}",
705	Vals&: return_pc, Vals: parent_func->GetName()));
706	}
707	Function *callee_func = call_edge->GetCallee(images&: modlist, exe_ctx&: parent_exe_ctx);
708	if (callee_func != current_func) {
709	return llvm::createStringError(
710	Fmt: "ambiguous call sequence, can't find real parent frame");
711	}
712	} else {
713	// The StackFrameList solver machinery has deduced that an unambiguous tail
714	// call sequence that produced the current activation. The first edge in
715	// the parent that points to the current function must be valid.
716	for (auto &edge : parent_func->GetTailCallingEdges()) {
717	if (edge->GetCallee(images&: modlist, exe_ctx&: parent_exe_ctx) == current_func) {
718	call_edge = edge.get();
719	break;
720	}
721	}
722	}
723	if (!call_edge)
724	return llvm::createStringError(Fmt: "no unambiguous edge from parent "
725	"to current function");
726
727	// 3. Attempt to locate the DW_OP_entry_value expression in the set of
728	// available call site parameters. If found, evaluate the corresponding
729	// parameter in the context of the parent frame.
730	const uint32_t subexpr_len = opcodes.GetULEB128(offset_ptr: &opcode_offset);
731	const void *subexpr_data = opcodes.GetData(offset_ptr: &opcode_offset, length: subexpr_len);
732	if (!subexpr_data)
733	return llvm::createStringError(Fmt: "subexpr could not be read");
734
735	const CallSiteParameter *matched_param = nullptr;
736	for (const CallSiteParameter &param : call_edge->GetCallSiteParameters()) {
737	DataExtractor param_subexpr_extractor;
738	if (!param.LocationInCallee.GetExpressionData(data&: param_subexpr_extractor))
739	continue;
740	lldb::offset_t param_subexpr_offset = 0;
741	const void *param_subexpr_data =
742	param_subexpr_extractor.GetData(offset_ptr: &param_subexpr_offset, length: subexpr_len);
743	if (!param_subexpr_data ||
744	param_subexpr_extractor.BytesLeft(offset: param_subexpr_offset) != 0)
745	continue;
746
747	// At this point, the DW_OP_entry_value sub-expression and the callee-side
748	// expression in the call site parameter are known to have the same length.
749	// Check whether they are equal.
750	//
751	// Note that an equality check is sufficient: the contents of the
752	// DW_OP_entry_value subexpression are only used to identify the right call
753	// site parameter in the parent, and do not require any special handling.
754	if (memcmp(s1: subexpr_data, s2: param_subexpr_data, n: subexpr_len) == 0) {
755	matched_param = &param;
756	break;
757	}
758	}
759	if (!matched_param)
760	return llvm::createStringError(Fmt: "no matching call site param found");
761
762	// TODO: Add support for DW_OP_push_object_address within a DW_OP_entry_value
763	// subexpresion whenever llvm does.
764	const DWARFExpressionList &param_expr = matched_param->LocationInCaller;
765
766	llvm::Expected<Value> maybe_result = param_expr.Evaluate(
767	exe_ctx: &parent_exe_ctx, reg_ctx: parent_frame->GetRegisterContext().get(),
768	LLDB_INVALID_ADDRESS,
769	/*initial_value_ptr=*/nullptr,
770	/*object_address_ptr=*/nullptr);
771	if (!maybe_result) {
772	LLDB_LOG(log,
773	"Evaluate_DW_OP_entry_value: call site param evaluation failed");
774	return maybe_result.takeError();
775	}
776
777	stack.push_back(x: *maybe_result);
778	return llvm::Error::success();
779	}
780
781	namespace {
782	/// The location description kinds described by the DWARF v5
783	/// specification. Composite locations are handled out-of-band and
784	/// thus aren't part of the enum.
785	enum LocationDescriptionKind {
786	Empty,
787	Memory,
788	Register,
789	Implicit
790	/* Composite*/
791	};
792	/// Adjust value's ValueType according to the kind of location description.
793	void UpdateValueTypeFromLocationDescription(
794	Log *log, const DWARFExpression::Delegate *dwarf_cu,
795	LocationDescriptionKind kind, Value *value = nullptr) {
796	// Note that this function is conflating DWARF expressions with
797	// DWARF location descriptions. Perhaps it would be better to define
798	// a wrapper for DWARFExpression::Eval() that deals with DWARF
799	// location descriptions (which consist of one or more DWARF
800	// expressions). But doing this would mean we'd also need factor the
801	// handling of DW_OP_(bit_)piece out of this function.
802	if (dwarf_cu && dwarf_cu->GetVersion() >= 4) {
803	const char *log_msg = "DWARF location description kind: %s";
804	switch (kind) {
805	case Empty:
806	LLDB_LOGF(log, log_msg, "Empty");
807	break;
808	case Memory:
809	LLDB_LOGF(log, log_msg, "Memory");
810	if (value->GetValueType() == Value::ValueType::Scalar)
811	value->SetValueType(Value::ValueType::LoadAddress);
812	break;
813	case Register:
814	LLDB_LOGF(log, log_msg, "Register");
815	value->SetValueType(Value::ValueType::Scalar);
816	break;
817	case Implicit:
818	LLDB_LOGF(log, log_msg, "Implicit");
819	if (value->GetValueType() == Value::ValueType::LoadAddress)
820	value->SetValueType(Value::ValueType::Scalar);
821	break;
822	}
823	}
824	}
825	} // namespace
826
827	/// Helper function to move common code used to resolve a file address and turn
828	/// into a load address.
829	///
830	/// \param exe_ctx Pointer to the execution context
831	/// \param module_sp shared_ptr contains the module if we have one
832	/// \param dw_op_type C-style string used to vary the error output
833	/// \param file_addr the file address we are trying to resolve and turn into a
834	/// load address
835	/// \param so_addr out parameter, will be set to load address or section offset
836	/// \param check_sectionoffset bool which determines if having a section offset
837	/// but not a load address is considerd a success
838	/// \returns std::optional containing the load address if resolving and getting
839	/// the load address succeed or an empty Optinal otherwise. If
840	/// check_sectionoffset is true we consider LLDB_INVALID_ADDRESS a
841	/// success if so_addr.IsSectionOffset() is true.
842	static llvm::Expected<lldb::addr_t>
843	ResolveLoadAddress(ExecutionContext *exe_ctx, lldb::ModuleSP &module_sp,
844	const char *dw_op_type, lldb::addr_t file_addr,
845	Address &so_addr, bool check_sectionoffset = false) {
846	if (!module_sp)
847	return llvm::createStringError(Fmt: "need module to resolve file address for %s",
848	Vals: dw_op_type);
849
850	if (!module_sp->ResolveFileAddress(vm_addr: file_addr, so_addr))
851	return llvm::createStringError(Fmt: "failed to resolve file address in module");
852
853	const addr_t load_addr = so_addr.GetLoadAddress(target: exe_ctx->GetTargetPtr());
854
855	if (load_addr == LLDB_INVALID_ADDRESS &&
856	(check_sectionoffset && !so_addr.IsSectionOffset()))
857	return llvm::createStringError(Fmt: "failed to resolve load address");
858
859	return load_addr;
860	}
861
862	/// Helper function to move common code used to load sized data from a uint8_t
863	/// buffer.
864	///
865	/// \param addr_bytes uint8_t buffer containg raw data
866	/// \param size_addr_bytes how large is the underlying raw data
867	/// \param byte_order what is the byter order of the underlyig data
868	/// \param size How much of the underlying data we want to use
869	/// \return The underlying data converted into a Scalar
870	static Scalar DerefSizeExtractDataHelper(uint8_t *addr_bytes,
871	size_t size_addr_bytes,
872	ByteOrder byte_order, size_t size) {
873	DataExtractor addr_data(addr_bytes, size_addr_bytes, byte_order, size);
874
875	lldb::offset_t addr_data_offset = 0;
876	if (size <= 8)
877	return addr_data.GetMaxU64(offset_ptr: &addr_data_offset, byte_size: size);
878	else
879	return addr_data.GetAddress(offset_ptr: &addr_data_offset);
880	}
881
882	llvm::Expected<Value> DWARFExpression::Evaluate(
883	ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
884	lldb::ModuleSP module_sp, const DataExtractor &opcodes,
885	const DWARFExpression::Delegate *dwarf_cu,
886	const lldb::RegisterKind reg_kind, const Value *initial_value_ptr,
887	const Value *object_address_ptr) {
888
889	if (opcodes.GetByteSize() == 0)
890	return llvm::createStringError(
891	Fmt: "no location, value may have been optimized out");
892	std::vector<Value> stack;
893
894	Process *process = nullptr;
895	StackFrame *frame = nullptr;
896	Target *target = nullptr;
897
898	if (exe_ctx) {
899	process = exe_ctx->GetProcessPtr();
900	frame = exe_ctx->GetFramePtr();
901	target = exe_ctx->GetTargetPtr();
902	}
903	if (reg_ctx == nullptr && frame)
904	reg_ctx = frame->GetRegisterContext().get();
905
906	if (initial_value_ptr)
907	stack.push_back(x: *initial_value_ptr);
908
909	lldb::offset_t offset = 0;
910	Value tmp;
911	uint32_t reg_num;
912
913	/// Insertion point for evaluating multi-piece expression.
914	uint64_t op_piece_offset = 0;
915	Value pieces; // Used for DW_OP_piece
916
917	Log *log = GetLog(mask: LLDBLog::Expressions);
918	// A generic type is "an integral type that has the size of an address and an
919	// unspecified signedness". For now, just use the signedness of the operand.
920	// TODO: Implement a real typed stack, and store the genericness of the value
921	// there.
922	auto to_generic = [&](auto v) {
923	// TODO: Avoid implicit trunc?
924	// See https://github.com/llvm/llvm-project/issues/112510.
925	bool is_signed = std::is_signed<decltype(v)>::value;
926	return Scalar(llvm::APSInt(llvm::APInt(8 * opcodes.GetAddressByteSize(), v,
927	is_signed, /*implicitTrunc=*/true),
928	!is_signed));
929	};
930
931	// The default kind is a memory location. This is updated by any
932	// operation that changes this, such as DW_OP_stack_value, and reset
933	// by composition operations like DW_OP_piece.
934	LocationDescriptionKind dwarf4_location_description_kind = Memory;
935
936	while (opcodes.ValidOffset(offset)) {
937	const lldb::offset_t op_offset = offset;
938	const uint8_t op = opcodes.GetU8(offset_ptr: &offset);
939
940	if (log && log->GetVerbose()) {
941	size_t count = stack.size();
942	LLDB_LOGF(log, "Stack before operation has %" PRIu64 " values:",
943	(uint64_t)count);
944	for (size_t i = 0; i < count; ++i) {
945	StreamString new_value;
946	new_value.Printf(format: "[%" PRIu64 "]", (uint64_t)i);
947	stack[i].Dump(strm: &new_value);
948	LLDB_LOGF(log, " %s", new_value.GetData());
949	}
950	LLDB_LOGF(log, "0x%8.8" PRIx64 ": %s", op_offset,
951	DW_OP_value_to_name(op));
952	}
953
954	if (std::optional<unsigned> arity =
955	llvm::dwarf::OperationArity(O: static_cast<LocationAtom>(op))) {
956	if (stack.size() < *arity)
957	return llvm::createStringError(
958	Fmt: "%s needs at least %d stack entries (stack has %d entries)",
959	Vals: DW_OP_value_to_name(val: op), Vals: *arity, Vals: stack.size());
960	}
961
962	switch (op) {
963	// The DW_OP_addr operation has a single operand that encodes a machine
964	// address and whose size is the size of an address on the target machine.
965	case DW_OP_addr:
966	stack.push_back(x: Scalar(opcodes.GetAddress(offset_ptr: &offset)));
967	if (target &&
968	target->GetArchitecture().GetCore() == ArchSpec::eCore_wasm32) {
969	// wasm file sections aren't mapped into memory, therefore addresses can
970	// never point into a file section and are always LoadAddresses.
971	stack.back().SetValueType(Value::ValueType::LoadAddress);
972	} else {
973	stack.back().SetValueType(Value::ValueType::FileAddress);
974	}
975	break;
976
977	// The DW_OP_addr_sect_offset4 is used for any location expressions in
978	// shared libraries that have a location like:
979	// DW_OP_addr(0x1000)
980	// If this address resides in a shared library, then this virtual address
981	// won't make sense when it is evaluated in the context of a running
982	// process where shared libraries have been slid. To account for this, this
983	// new address type where we can store the section pointer and a 4 byte
984	// offset.
985	// case DW_OP_addr_sect_offset4:
986	// {
987	// result_type = eResultTypeFileAddress;
988	// lldb::Section *sect = (lldb::Section
989	// *)opcodes.GetMaxU64(&offset, sizeof(void *));
990	// lldb::addr_t sect_offset = opcodes.GetU32(&offset);
991	//
992	// Address so_addr (sect, sect_offset);
993	// lldb::addr_t load_addr = so_addr.GetLoadAddress();
994	// if (load_addr != LLDB_INVALID_ADDRESS)
995	// {
996	// // We successfully resolve a file address to a load
997	// // address.
998	// stack.push_back(load_addr);
999	// break;
1000	// }
1001	// else
1002	// {
1003	// // We were able
1004	// if (error_ptr)
1005	// error_ptr->SetErrorStringWithFormat ("Section %s in
1006	// %s is not currently loaded.\n",
1007	// sect->GetName().AsCString(),
1008	// sect->GetModule()->GetFileSpec().GetFilename().AsCString());
1009	// return false;
1010	// }
1011	// }
1012	// break;
1013
1014	// OPCODE: DW_OP_deref
1015	// OPERANDS: none
1016	// DESCRIPTION: Pops the top stack entry and treats it as an address.
1017	// The value retrieved from that address is pushed. The size of the data
1018	// retrieved from the dereferenced address is the size of an address on the
1019	// target machine.
1020	case DW_OP_deref: {
1021	if (stack.empty())
1022	return llvm::createStringError(
1023	Fmt: "expression stack empty for DW_OP_deref");
1024	Value::ValueType value_type = stack.back().GetValueType();
1025	switch (value_type) {
1026	case Value::ValueType::HostAddress: {
1027	void *src = (void *)stack.back().GetScalar().ULongLong();
1028	intptr_t ptr;
1029	::memcpy(dest: &ptr, src: src, n: sizeof(void *));
1030	stack.back().GetScalar() = ptr;
1031	stack.back().ClearContext();
1032	} break;
1033	case Value::ValueType::FileAddress: {
1034	auto file_addr = stack.back().GetScalar().ULongLong(
1035	LLDB_INVALID_ADDRESS);
1036
1037	Address so_addr;
1038	auto maybe_load_addr = ResolveLoadAddress(
1039	exe_ctx, module_sp, dw_op_type: "DW_OP_deref", file_addr, so_addr);
1040
1041	if (!maybe_load_addr)
1042	return maybe_load_addr.takeError();
1043
1044	stack.back().GetScalar() = *maybe_load_addr;
1045	// Fall through to load address promotion code below.
1046	}
1047	[[fallthrough]];
1048	case Value::ValueType::Scalar:
1049	// Promote Scalar to LoadAddress and fall through.
1050	stack.back().SetValueType(Value::ValueType::LoadAddress);
1051	[[fallthrough]];
1052	case Value::ValueType::LoadAddress:
1053	if (exe_ctx) {
1054	if (process) {
1055	lldb::addr_t pointer_addr =
1056	stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
1057	Status error;
1058	lldb::addr_t pointer_value =
1059	process->ReadPointerFromMemory(vm_addr: pointer_addr, error);
1060	if (pointer_value != LLDB_INVALID_ADDRESS) {
1061	if (ABISP abi_sp = process->GetABI())
1062	pointer_value = abi_sp->FixCodeAddress(pc: pointer_value);
1063	stack.back().GetScalar() = pointer_value;
1064	stack.back().ClearContext();
1065	} else {
1066	return llvm::createStringError(
1067	Fmt: "Failed to dereference pointer from 0x%" PRIx64
1068	" for DW_OP_deref: %s\n",
1069	Vals: pointer_addr, Vals: error.AsCString());
1070	}
1071	} else {
1072	return llvm::createStringError(Fmt: "NULL process for DW_OP_deref");
1073	}
1074	} else {
1075	return llvm::createStringError(
1076	Fmt: "NULL execution context for DW_OP_deref");
1077	}
1078	break;
1079
1080	case Value::ValueType::Invalid:
1081	return llvm::createStringError(Fmt: "invalid value type for DW_OP_deref");
1082	}
1083
1084	} break;
1085
1086	// OPCODE: DW_OP_deref_size
1087	// OPERANDS: 1
1088	// 1 - uint8_t that specifies the size of the data to dereference.
1089	// DESCRIPTION: Behaves like the DW_OP_deref operation: it pops the top
1090	// stack entry and treats it as an address. The value retrieved from that
1091	// address is pushed. In the DW_OP_deref_size operation, however, the size
1092	// in bytes of the data retrieved from the dereferenced address is
1093	// specified by the single operand. This operand is a 1-byte unsigned
1094	// integral constant whose value may not be larger than the size of an
1095	// address on the target machine. The data retrieved is zero extended to
1096	// the size of an address on the target machine before being pushed on the
1097	// expression stack.
1098	case DW_OP_deref_size: {
1099	if (stack.empty()) {
1100	return llvm::createStringError(
1101	Fmt: "expression stack empty for DW_OP_deref_size");
1102	}
1103	uint8_t size = opcodes.GetU8(offset_ptr: &offset);
1104	if (size > 8) {
1105	return llvm::createStringError(
1106	Fmt: "Invalid address size for DW_OP_deref_size: %d\n", Vals: size);
1107	}
1108	Value::ValueType value_type = stack.back().GetValueType();
1109	switch (value_type) {
1110	case Value::ValueType::HostAddress: {
1111	void *src = (void *)stack.back().GetScalar().ULongLong();
1112	intptr_t ptr;
1113	::memcpy(dest: &ptr, src: src, n: sizeof(void *));
1114	// I can't decide whether the size operand should apply to the bytes in
1115	// their
1116	// lldb-host endianness or the target endianness.. I doubt this'll ever
1117	// come up but I'll opt for assuming big endian regardless.
1118	switch (size) {
1119	case 1:
1120	ptr = ptr & 0xff;
1121	break;
1122	case 2:
1123	ptr = ptr & 0xffff;
1124	break;
1125	case 3:
1126	ptr = ptr & 0xffffff;
1127	break;
1128	case 4:
1129	ptr = ptr & 0xffffffff;
1130	break;
1131	// the casts are added to work around the case where intptr_t is a 32
1132	// bit quantity;
1133	// presumably we won't hit the 5..7 cases if (void*) is 32-bits in this
1134	// program.
1135	case 5:
1136	ptr = (intptr_t)ptr & 0xffffffffffULL;
1137	break;
1138	case 6:
1139	ptr = (intptr_t)ptr & 0xffffffffffffULL;
1140	break;
1141	case 7:
1142	ptr = (intptr_t)ptr & 0xffffffffffffffULL;
1143	break;
1144	default:
1145	break;
1146	}
1147	stack.back().GetScalar() = ptr;
1148	stack.back().ClearContext();
1149	} break;
1150	case Value::ValueType::FileAddress: {
1151	auto file_addr =
1152	stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
1153	Address so_addr;
1154	auto maybe_load_addr = ResolveLoadAddress(
1155	exe_ctx, module_sp, dw_op_type: "DW_OP_deref_size", file_addr, so_addr,
1156	/*check_sectionoffset=*/true);
1157
1158	if (!maybe_load_addr)
1159	return maybe_load_addr.takeError();
1160
1161	addr_t load_addr = *maybe_load_addr;
1162
1163	if (load_addr == LLDB_INVALID_ADDRESS && so_addr.IsSectionOffset()) {
1164	uint8_t addr_bytes[8];
1165	Status error;
1166
1167	if (target &&
1168	target->ReadMemory(addr: so_addr, dst: &addr_bytes, dst_len: size, error,
1169	/*force_live_memory=*/false) == size) {
1170	ObjectFile *objfile = module_sp->GetObjectFile();
1171
1172	stack.back().GetScalar() = DerefSizeExtractDataHelper(
1173	addr_bytes, size_addr_bytes: size, byte_order: objfile->GetByteOrder(), size);
1174	stack.back().ClearContext();
1175	break;
1176	} else {
1177	return llvm::createStringError(
1178	Fmt: "Failed to dereference pointer for DW_OP_deref_size: "
1179	"%s\n",
1180	Vals: error.AsCString());
1181	}
1182	}
1183	stack.back().GetScalar() = load_addr;
1184	// Fall through to load address promotion code below.
1185	}
1186
1187	[[fallthrough]];
1188	case Value::ValueType::Scalar:
1189	case Value::ValueType::LoadAddress:
1190	if (exe_ctx) {
1191	if (process) {
1192	lldb::addr_t pointer_addr =
1193	stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
1194	uint8_t addr_bytes[sizeof(lldb::addr_t)];
1195	Status error;
1196	if (process->ReadMemory(vm_addr: pointer_addr, buf: &addr_bytes, size, error) ==
1197	size) {
1198
1199	stack.back().GetScalar() =
1200	DerefSizeExtractDataHelper(addr_bytes, size_addr_bytes: sizeof(addr_bytes),
1201	byte_order: process->GetByteOrder(), size);
1202	stack.back().ClearContext();
1203	} else {
1204	return llvm::createStringError(
1205	Fmt: "Failed to dereference pointer from 0x%" PRIx64
1206	" for DW_OP_deref: %s\n",
1207	Vals: pointer_addr, Vals: error.AsCString());
1208	}
1209	} else {
1210
1211	return llvm::createStringError(Fmt: "NULL process for DW_OP_deref_size");
1212	}
1213	} else {
1214	return llvm::createStringError(
1215	Fmt: "NULL execution context for DW_OP_deref_size");
1216	}
1217	break;
1218
1219	case Value::ValueType::Invalid:
1220
1221	return llvm::createStringError(Fmt: "invalid value for DW_OP_deref_size");
1222	}
1223
1224	} break;
1225
1226	// OPCODE: DW_OP_xderef_size
1227	// OPERANDS: 1
1228	// 1 - uint8_t that specifies the size of the data to dereference.
1229	// DESCRIPTION: Behaves like the DW_OP_xderef operation: the entry at
1230	// the top of the stack is treated as an address. The second stack entry is
1231	// treated as an "address space identifier" for those architectures that
1232	// support multiple address spaces. The top two stack elements are popped,
1233	// a data item is retrieved through an implementation-defined address
1234	// calculation and pushed as the new stack top. In the DW_OP_xderef_size
1235	// operation, however, the size in bytes of the data retrieved from the
1236	// dereferenced address is specified by the single operand. This operand is
1237	// a 1-byte unsigned integral constant whose value may not be larger than
1238	// the size of an address on the target machine. The data retrieved is zero
1239	// extended to the size of an address on the target machine before being
1240	// pushed on the expression stack.
1241	case DW_OP_xderef_size:
1242	return llvm::createStringError(Fmt: "unimplemented opcode: DW_OP_xderef_size");
1243	// OPCODE: DW_OP_xderef
1244	// OPERANDS: none
1245	// DESCRIPTION: Provides an extended dereference mechanism. The entry at
1246	// the top of the stack is treated as an address. The second stack entry is
1247	// treated as an "address space identifier" for those architectures that
1248	// support multiple address spaces. The top two stack elements are popped,
1249	// a data item is retrieved through an implementation-defined address
1250	// calculation and pushed as the new stack top. The size of the data
1251	// retrieved from the dereferenced address is the size of an address on the
1252	// target machine.
1253	case DW_OP_xderef:
1254	return llvm::createStringError(Fmt: "unimplemented opcode: DW_OP_xderef");
1255
1256	// All DW_OP_constXXX opcodes have a single operand as noted below:
1257	//
1258	// Opcode Operand 1
1259	// DW_OP_const1u 1-byte unsigned integer constant
1260	// DW_OP_const1s 1-byte signed integer constant
1261	// DW_OP_const2u 2-byte unsigned integer constant
1262	// DW_OP_const2s 2-byte signed integer constant
1263	// DW_OP_const4u 4-byte unsigned integer constant
1264	// DW_OP_const4s 4-byte signed integer constant
1265	// DW_OP_const8u 8-byte unsigned integer constant
1266	// DW_OP_const8s 8-byte signed integer constant
1267	// DW_OP_constu unsigned LEB128 integer constant
1268	// DW_OP_consts signed LEB128 integer constant
1269	case DW_OP_const1u:
1270	stack.push_back(x: to_generic(opcodes.GetU8(offset_ptr: &offset)));
1271	break;
1272	case DW_OP_const1s:
1273	stack.push_back(x: to_generic((int8_t)opcodes.GetU8(offset_ptr: &offset)));
1274	break;
1275	case DW_OP_const2u:
1276	stack.push_back(x: to_generic(opcodes.GetU16(offset_ptr: &offset)));
1277	break;
1278	case DW_OP_const2s:
1279	stack.push_back(x: to_generic((int16_t)opcodes.GetU16(offset_ptr: &offset)));
1280	break;
1281	case DW_OP_const4u:
1282	stack.push_back(x: to_generic(opcodes.GetU32(offset_ptr: &offset)));
1283	break;
1284	case DW_OP_const4s:
1285	stack.push_back(x: to_generic((int32_t)opcodes.GetU32(offset_ptr: &offset)));
1286	break;
1287	case DW_OP_const8u:
1288	stack.push_back(x: to_generic(opcodes.GetU64(offset_ptr: &offset)));
1289	break;
1290	case DW_OP_const8s:
1291	stack.push_back(x: to_generic((int64_t)opcodes.GetU64(offset_ptr: &offset)));
1292	break;
1293	// These should also use to_generic, but we can't do that due to a
1294	// producer-side bug in llvm. See llvm.org/pr48087.
1295	case DW_OP_constu:
1296	stack.push_back(x: Scalar(opcodes.GetULEB128(offset_ptr: &offset)));
1297	break;
1298	case DW_OP_consts:
1299	stack.push_back(x: Scalar(opcodes.GetSLEB128(offset_ptr: &offset)));
1300	break;
1301
1302	// OPCODE: DW_OP_dup
1303	// OPERANDS: none
1304	// DESCRIPTION: duplicates the value at the top of the stack
1305	case DW_OP_dup:
1306	if (stack.empty()) {
1307	return llvm::createStringError(Fmt: "expression stack empty for DW_OP_dup");
1308	} else
1309	stack.push_back(x: stack.back());
1310	break;
1311
1312	// OPCODE: DW_OP_drop
1313	// OPERANDS: none
1314	// DESCRIPTION: pops the value at the top of the stack
1315	case DW_OP_drop:
1316	if (stack.empty()) {
1317	return llvm::createStringError(Fmt: "expression stack empty for DW_OP_drop");
1318	} else
1319	stack.pop_back();
1320	break;
1321
1322	// OPCODE: DW_OP_over
1323	// OPERANDS: none
1324	// DESCRIPTION: Duplicates the entry currently second in the stack at
1325	// the top of the stack.
1326	case DW_OP_over:
1327	stack.push_back(x: stack[stack.size() - 2]);
1328	break;
1329
1330	// OPCODE: DW_OP_pick
1331	// OPERANDS: uint8_t index into the current stack
1332	// DESCRIPTION: The stack entry with the specified index (0 through 255,
1333	// inclusive) is pushed on the stack
1334	case DW_OP_pick: {
1335	uint8_t pick_idx = opcodes.GetU8(offset_ptr: &offset);
1336	if (pick_idx < stack.size())
1337	stack.push_back(x: stack[stack.size() - 1 - pick_idx]);
1338	else {
1339	return llvm::createStringError(
1340	Fmt: "Index %u out of range for DW_OP_pick.\n", Vals: pick_idx);
1341	}
1342	} break;
1343
1344	// OPCODE: DW_OP_swap
1345	// OPERANDS: none
1346	// DESCRIPTION: swaps the top two stack entries. The entry at the top
1347	// of the stack becomes the second stack entry, and the second entry
1348	// becomes the top of the stack
1349	case DW_OP_swap:
1350	tmp = stack.back();
1351	stack.back() = stack[stack.size() - 2];
1352	stack[stack.size() - 2] = tmp;
1353	break;
1354
1355	// OPCODE: DW_OP_rot
1356	// OPERANDS: none
1357	// DESCRIPTION: Rotates the first three stack entries. The entry at
1358	// the top of the stack becomes the third stack entry, the second entry
1359	// becomes the top of the stack, and the third entry becomes the second
1360	// entry.
1361	case DW_OP_rot: {
1362	size_t last_idx = stack.size() - 1;
1363	Value old_top = stack[last_idx];
1364	stack[last_idx] = stack[last_idx - 1];
1365	stack[last_idx - 1] = stack[last_idx - 2];
1366	stack[last_idx - 2] = old_top;
1367	} break;
1368
1369	// OPCODE: DW_OP_abs
1370	// OPERANDS: none
1371	// DESCRIPTION: pops the top stack entry, interprets it as a signed
1372	// value and pushes its absolute value. If the absolute value can not be
1373	// represented, the result is undefined.
1374	case DW_OP_abs:
1375	if (!stack.back().ResolveValue(exe_ctx).AbsoluteValue()) {
1376	return llvm::createStringError(
1377	Fmt: "failed to take the absolute value of the first stack item");
1378	}
1379	break;
1380
1381	// OPCODE: DW_OP_and
1382	// OPERANDS: none
1383	// DESCRIPTION: pops the top two stack values, performs a bitwise and
1384	// operation on the two, and pushes the result.
1385	case DW_OP_and:
1386	tmp = stack.back();
1387	stack.pop_back();
1388	stack.back().ResolveValue(exe_ctx) =
1389	stack.back().ResolveValue(exe_ctx) & tmp.ResolveValue(exe_ctx);
1390	break;
1391
1392	// OPCODE: DW_OP_div
1393	// OPERANDS: none
1394	// DESCRIPTION: pops the top two stack values, divides the former second
1395	// entry by the former top of the stack using signed division, and pushes
1396	// the result.
1397	case DW_OP_div: {
1398	tmp = stack.back();
1399	if (tmp.ResolveValue(exe_ctx).IsZero())
1400	return llvm::createStringError(Fmt: "divide by zero");
1401
1402	stack.pop_back();
1403	Scalar divisor, dividend;
1404	divisor = tmp.ResolveValue(exe_ctx);
1405	dividend = stack.back().ResolveValue(exe_ctx);
1406	divisor.MakeSigned();
1407	dividend.MakeSigned();
1408	stack.back() = dividend / divisor;
1409
1410	if (!stack.back().ResolveValue(exe_ctx).IsValid())
1411	return llvm::createStringError(Fmt: "divide failed");
1412	} break;
1413
1414	// OPCODE: DW_OP_minus
1415	// OPERANDS: none
1416	// DESCRIPTION: pops the top two stack values, subtracts the former top
1417	// of the stack from the former second entry, and pushes the result.
1418	case DW_OP_minus:
1419	tmp = stack.back();
1420	stack.pop_back();
1421	stack.back().ResolveValue(exe_ctx) =
1422	stack.back().ResolveValue(exe_ctx) - tmp.ResolveValue(exe_ctx);
1423	break;
1424
1425	// OPCODE: DW_OP_mod
1426	// OPERANDS: none
1427	// DESCRIPTION: pops the top two stack values and pushes the result of
1428	// the calculation: former second stack entry modulo the former top of the
1429	// stack.
1430	case DW_OP_mod:
1431	tmp = stack.back();
1432	stack.pop_back();
1433	stack.back().ResolveValue(exe_ctx) =
1434	stack.back().ResolveValue(exe_ctx) % tmp.ResolveValue(exe_ctx);
1435	break;
1436
1437	// OPCODE: DW_OP_mul
1438	// OPERANDS: none
1439	// DESCRIPTION: pops the top two stack entries, multiplies them
1440	// together, and pushes the result.
1441	case DW_OP_mul:
1442	tmp = stack.back();
1443	stack.pop_back();
1444	stack.back().ResolveValue(exe_ctx) =
1445	stack.back().ResolveValue(exe_ctx) * tmp.ResolveValue(exe_ctx);
1446	break;
1447
1448	// OPCODE: DW_OP_neg
1449	// OPERANDS: none
1450	// DESCRIPTION: pops the top stack entry, and pushes its negation.
1451	case DW_OP_neg:
1452	if (!stack.back().ResolveValue(exe_ctx).UnaryNegate())
1453	return llvm::createStringError(Fmt: "unary negate failed");
1454	break;
1455
1456	// OPCODE: DW_OP_not
1457	// OPERANDS: none
1458	// DESCRIPTION: pops the top stack entry, and pushes its bitwise
1459	// complement
1460	case DW_OP_not:
1461	if (!stack.back().ResolveValue(exe_ctx).OnesComplement())
1462	return llvm::createStringError(Fmt: "logical NOT failed");
1463	break;
1464
1465	// OPCODE: DW_OP_or
1466	// OPERANDS: none
1467	// DESCRIPTION: pops the top two stack entries, performs a bitwise or
1468	// operation on the two, and pushes the result.
1469	case DW_OP_or:
1470	tmp = stack.back();
1471	stack.pop_back();
1472	stack.back().ResolveValue(exe_ctx) =
1473	stack.back().ResolveValue(exe_ctx) | tmp.ResolveValue(exe_ctx);
1474	break;
1475
1476	// OPCODE: DW_OP_plus
1477	// OPERANDS: none
1478	// DESCRIPTION: pops the top two stack entries, adds them together, and
1479	// pushes the result.
1480	case DW_OP_plus:
1481	tmp = stack.back();
1482	stack.pop_back();
1483	stack.back().GetScalar() += tmp.GetScalar();
1484	break;
1485
1486	// OPCODE: DW_OP_plus_uconst
1487	// OPERANDS: none
1488	// DESCRIPTION: pops the top stack entry, adds it to the unsigned LEB128
1489	// constant operand and pushes the result.
1490	case DW_OP_plus_uconst: {
1491	const uint64_t uconst_value = opcodes.GetULEB128(offset_ptr: &offset);
1492	// Implicit conversion from a UINT to a Scalar...
1493	stack.back().GetScalar() += uconst_value;
1494	if (!stack.back().GetScalar().IsValid())
1495	return llvm::createStringError(Fmt: "DW_OP_plus_uconst failed");
1496	} break;
1497
1498	// OPCODE: DW_OP_shl
1499	// OPERANDS: none
1500	// DESCRIPTION: pops the top two stack entries, shifts the former
1501	// second entry left by the number of bits specified by the former top of
1502	// the stack, and pushes the result.
1503	case DW_OP_shl:
1504	tmp = stack.back();
1505	stack.pop_back();
1506	stack.back().ResolveValue(exe_ctx) <<= tmp.ResolveValue(exe_ctx);
1507	break;
1508
1509	// OPCODE: DW_OP_shr
1510	// OPERANDS: none
1511	// DESCRIPTION: pops the top two stack entries, shifts the former second
1512	// entry right logically (filling with zero bits) by the number of bits
1513	// specified by the former top of the stack, and pushes the result.
1514	case DW_OP_shr:
1515	tmp = stack.back();
1516	stack.pop_back();
1517	if (!stack.back().ResolveValue(exe_ctx).ShiftRightLogical(
1518	rhs: tmp.ResolveValue(exe_ctx)))
1519	return llvm::createStringError(Fmt: "DW_OP_shr failed");
1520	break;
1521
1522	// OPCODE: DW_OP_shra
1523	// OPERANDS: none
1524	// DESCRIPTION: pops the top two stack entries, shifts the former second
1525	// entry right arithmetically (divide the magnitude by 2, keep the same
1526	// sign for the result) by the number of bits specified by the former top
1527	// of the stack, and pushes the result.
1528	case DW_OP_shra:
1529	tmp = stack.back();
1530	stack.pop_back();
1531	stack.back().ResolveValue(exe_ctx) >>= tmp.ResolveValue(exe_ctx);
1532	break;
1533
1534	// OPCODE: DW_OP_xor
1535	// OPERANDS: none
1536	// DESCRIPTION: pops the top two stack entries, performs the bitwise
1537	// exclusive-or operation on the two, and pushes the result.
1538	case DW_OP_xor:
1539	tmp = stack.back();
1540	stack.pop_back();
1541	stack.back().ResolveValue(exe_ctx) =
1542	stack.back().ResolveValue(exe_ctx) ^ tmp.ResolveValue(exe_ctx);
1543	break;
1544
1545	// OPCODE: DW_OP_skip
1546	// OPERANDS: int16_t
1547	// DESCRIPTION: An unconditional branch. Its single operand is a 2-byte
1548	// signed integer constant. The 2-byte constant is the number of bytes of
1549	// the DWARF expression to skip forward or backward from the current
1550	// operation, beginning after the 2-byte constant.
1551	case DW_OP_skip: {
1552	int16_t skip_offset = (int16_t)opcodes.GetU16(offset_ptr: &offset);
1553	lldb::offset_t new_offset = offset + skip_offset;
1554	// New offset can point at the end of the data, in this case we should
1555	// terminate the DWARF expression evaluation (will happen in the loop
1556	// condition).
1557	if (new_offset <= opcodes.GetByteSize())
1558	offset = new_offset;
1559	else {
1560	return llvm::createStringError(S: llvm::formatv(
1561	Fmt: "Invalid opcode offset in DW_OP_skip: {0}+({1}) > {2}", Vals&: offset,
1562	Vals&: skip_offset, Vals: opcodes.GetByteSize()));
1563	}
1564	} break;
1565
1566	// OPCODE: DW_OP_bra
1567	// OPERANDS: int16_t
1568	// DESCRIPTION: A conditional branch. Its single operand is a 2-byte
1569	// signed integer constant. This operation pops the top of stack. If the
1570	// value popped is not the constant 0, the 2-byte constant operand is the
1571	// number of bytes of the DWARF expression to skip forward or backward from
1572	// the current operation, beginning after the 2-byte constant.
1573	case DW_OP_bra: {
1574	tmp = stack.back();
1575	stack.pop_back();
1576	int16_t bra_offset = (int16_t)opcodes.GetU16(offset_ptr: &offset);
1577	Scalar zero(0);
1578	if (tmp.ResolveValue(exe_ctx) != zero) {
1579	lldb::offset_t new_offset = offset + bra_offset;
1580	// New offset can point at the end of the data, in this case we should
1581	// terminate the DWARF expression evaluation (will happen in the loop
1582	// condition).
1583	if (new_offset <= opcodes.GetByteSize())
1584	offset = new_offset;
1585	else {
1586	return llvm::createStringError(S: llvm::formatv(
1587	Fmt: "Invalid opcode offset in DW_OP_bra: {0}+({1}) > {2}", Vals&: offset,
1588	Vals&: bra_offset, Vals: opcodes.GetByteSize()));
1589	}
1590	}
1591	} break;
1592
1593	// OPCODE: DW_OP_eq
1594	// OPERANDS: none
1595	// DESCRIPTION: pops the top two stack values, compares using the
1596	// equals (==) operator.
1597	// STACK RESULT: push the constant value 1 onto the stack if the result
1598	// of the operation is true or the constant value 0 if the result of the
1599	// operation is false.
1600	case DW_OP_eq:
1601	tmp = stack.back();
1602	stack.pop_back();
1603	stack.back().ResolveValue(exe_ctx) =
1604	stack.back().ResolveValue(exe_ctx) == tmp.ResolveValue(exe_ctx);
1605	break;
1606
1607	// OPCODE: DW_OP_ge
1608	// OPERANDS: none
1609	// DESCRIPTION: pops the top two stack values, compares using the
1610	// greater than or equal to (>=) operator.
1611	// STACK RESULT: push the constant value 1 onto the stack if the result
1612	// of the operation is true or the constant value 0 if the result of the
1613	// operation is false.
1614	case DW_OP_ge:
1615	tmp = stack.back();
1616	stack.pop_back();
1617	stack.back().ResolveValue(exe_ctx) =
1618	stack.back().ResolveValue(exe_ctx) >= tmp.ResolveValue(exe_ctx);
1619	break;
1620
1621	// OPCODE: DW_OP_gt
1622	// OPERANDS: none
1623	// DESCRIPTION: pops the top two stack values, compares using the
1624	// greater than (>) operator.
1625	// STACK RESULT: push the constant value 1 onto the stack if the result
1626	// of the operation is true or the constant value 0 if the result of the
1627	// operation is false.
1628	case DW_OP_gt:
1629	tmp = stack.back();
1630	stack.pop_back();
1631	stack.back().ResolveValue(exe_ctx) =
1632	stack.back().ResolveValue(exe_ctx) > tmp.ResolveValue(exe_ctx);
1633	break;
1634
1635	// OPCODE: DW_OP_le
1636	// OPERANDS: none
1637	// DESCRIPTION: pops the top two stack values, compares using the
1638	// less than or equal to (<=) operator.
1639	// STACK RESULT: push the constant value 1 onto the stack if the result
1640	// of the operation is true or the constant value 0 if the result of the
1641	// operation is false.
1642	case DW_OP_le:
1643	tmp = stack.back();
1644	stack.pop_back();
1645	stack.back().ResolveValue(exe_ctx) =
1646	stack.back().ResolveValue(exe_ctx) <= tmp.ResolveValue(exe_ctx);
1647	break;
1648
1649	// OPCODE: DW_OP_lt
1650	// OPERANDS: none
1651	// DESCRIPTION: pops the top two stack values, compares using the
1652	// less than (<) operator.
1653	// STACK RESULT: push the constant value 1 onto the stack if the result
1654	// of the operation is true or the constant value 0 if the result of the
1655	// operation is false.
1656	case DW_OP_lt:
1657	tmp = stack.back();
1658	stack.pop_back();
1659	stack.back().ResolveValue(exe_ctx) =
1660	stack.back().ResolveValue(exe_ctx) < tmp.ResolveValue(exe_ctx);
1661	break;
1662
1663	// OPCODE: DW_OP_ne
1664	// OPERANDS: none
1665	// DESCRIPTION: pops the top two stack values, compares using the
1666	// not equal (!=) operator.
1667	// STACK RESULT: push the constant value 1 onto the stack if the result
1668	// of the operation is true or the constant value 0 if the result of the
1669	// operation is false.
1670	case DW_OP_ne:
1671	tmp = stack.back();
1672	stack.pop_back();
1673	stack.back().ResolveValue(exe_ctx) =
1674	stack.back().ResolveValue(exe_ctx) != tmp.ResolveValue(exe_ctx);
1675	break;
1676
1677	// OPCODE: DW_OP_litn
1678	// OPERANDS: none
1679	// DESCRIPTION: encode the unsigned literal values from 0 through 31.
1680	// STACK RESULT: push the unsigned literal constant value onto the top
1681	// of the stack.
1682	case DW_OP_lit0:
1683	case DW_OP_lit1:
1684	case DW_OP_lit2:
1685	case DW_OP_lit3:
1686	case DW_OP_lit4:
1687	case DW_OP_lit5:
1688	case DW_OP_lit6:
1689	case DW_OP_lit7:
1690	case DW_OP_lit8:
1691	case DW_OP_lit9:
1692	case DW_OP_lit10:
1693	case DW_OP_lit11:
1694	case DW_OP_lit12:
1695	case DW_OP_lit13:
1696	case DW_OP_lit14:
1697	case DW_OP_lit15:
1698	case DW_OP_lit16:
1699	case DW_OP_lit17:
1700	case DW_OP_lit18:
1701	case DW_OP_lit19:
1702	case DW_OP_lit20:
1703	case DW_OP_lit21:
1704	case DW_OP_lit22:
1705	case DW_OP_lit23:
1706	case DW_OP_lit24:
1707	case DW_OP_lit25:
1708	case DW_OP_lit26:
1709	case DW_OP_lit27:
1710	case DW_OP_lit28:
1711	case DW_OP_lit29:
1712	case DW_OP_lit30:
1713	case DW_OP_lit31:
1714	stack.push_back(x: to_generic(op - DW_OP_lit0));
1715	break;
1716
1717	// OPCODE: DW_OP_regN
1718	// OPERANDS: none
1719	// DESCRIPTION: Push the value in register n on the top of the stack.
1720	case DW_OP_reg0:
1721	case DW_OP_reg1:
1722	case DW_OP_reg2:
1723	case DW_OP_reg3:
1724	case DW_OP_reg4:
1725	case DW_OP_reg5:
1726	case DW_OP_reg6:
1727	case DW_OP_reg7:
1728	case DW_OP_reg8:
1729	case DW_OP_reg9:
1730	case DW_OP_reg10:
1731	case DW_OP_reg11:
1732	case DW_OP_reg12:
1733	case DW_OP_reg13:
1734	case DW_OP_reg14:
1735	case DW_OP_reg15:
1736	case DW_OP_reg16:
1737	case DW_OP_reg17:
1738	case DW_OP_reg18:
1739	case DW_OP_reg19:
1740	case DW_OP_reg20:
1741	case DW_OP_reg21:
1742	case DW_OP_reg22:
1743	case DW_OP_reg23:
1744	case DW_OP_reg24:
1745	case DW_OP_reg25:
1746	case DW_OP_reg26:
1747	case DW_OP_reg27:
1748	case DW_OP_reg28:
1749	case DW_OP_reg29:
1750	case DW_OP_reg30:
1751	case DW_OP_reg31: {
1752	dwarf4_location_description_kind = Register;
1753	reg_num = op - DW_OP_reg0;
1754
1755	if (llvm::Error err =
1756	ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, value&: tmp))
1757	return err;
1758	stack.push_back(x: tmp);
1759	} break;
1760	// OPCODE: DW_OP_regx
1761	// OPERANDS:
1762	// ULEB128 literal operand that encodes the register.
1763	// DESCRIPTION: Push the value in register on the top of the stack.
1764	case DW_OP_regx: {
1765	dwarf4_location_description_kind = Register;
1766	reg_num = opcodes.GetULEB128(offset_ptr: &offset);
1767	Status read_err;
1768	if (llvm::Error err =
1769	ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, value&: tmp))
1770	return err;
1771	stack.push_back(x: tmp);
1772	} break;
1773
1774	// OPCODE: DW_OP_bregN
1775	// OPERANDS:
1776	// SLEB128 offset from register N
1777	// DESCRIPTION: Value is in memory at the address specified by register
1778	// N plus an offset.
1779	case DW_OP_breg0:
1780	case DW_OP_breg1:
1781	case DW_OP_breg2:
1782	case DW_OP_breg3:
1783	case DW_OP_breg4:
1784	case DW_OP_breg5:
1785	case DW_OP_breg6:
1786	case DW_OP_breg7:
1787	case DW_OP_breg8:
1788	case DW_OP_breg9:
1789	case DW_OP_breg10:
1790	case DW_OP_breg11:
1791	case DW_OP_breg12:
1792	case DW_OP_breg13:
1793	case DW_OP_breg14:
1794	case DW_OP_breg15:
1795	case DW_OP_breg16:
1796	case DW_OP_breg17:
1797	case DW_OP_breg18:
1798	case DW_OP_breg19:
1799	case DW_OP_breg20:
1800	case DW_OP_breg21:
1801	case DW_OP_breg22:
1802	case DW_OP_breg23:
1803	case DW_OP_breg24:
1804	case DW_OP_breg25:
1805	case DW_OP_breg26:
1806	case DW_OP_breg27:
1807	case DW_OP_breg28:
1808	case DW_OP_breg29:
1809	case DW_OP_breg30:
1810	case DW_OP_breg31: {
1811	reg_num = op - DW_OP_breg0;
1812	if (llvm::Error err =
1813	ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, value&: tmp))
1814	return err;
1815
1816	int64_t breg_offset = opcodes.GetSLEB128(offset_ptr: &offset);
1817	tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
1818	tmp.ClearContext();
1819	stack.push_back(x: tmp);
1820	stack.back().SetValueType(Value::ValueType::LoadAddress);
1821	} break;
1822	// OPCODE: DW_OP_bregx
1823	// OPERANDS: 2
1824	// ULEB128 literal operand that encodes the register.
1825	// SLEB128 offset from register N
1826	// DESCRIPTION: Value is in memory at the address specified by register
1827	// N plus an offset.
1828	case DW_OP_bregx: {
1829	reg_num = opcodes.GetULEB128(offset_ptr: &offset);
1830	if (llvm::Error err =
1831	ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, value&: tmp))
1832	return err;
1833
1834	int64_t breg_offset = opcodes.GetSLEB128(offset_ptr: &offset);
1835	tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
1836	tmp.ClearContext();
1837	stack.push_back(x: tmp);
1838	stack.back().SetValueType(Value::ValueType::LoadAddress);
1839	} break;
1840
1841	case DW_OP_fbreg:
1842	if (exe_ctx) {
1843	if (frame) {
1844	Scalar value;
1845	if (llvm::Error err = frame->GetFrameBaseValue(value))
1846	return err;
1847	int64_t fbreg_offset = opcodes.GetSLEB128(offset_ptr: &offset);
1848	value += fbreg_offset;
1849	stack.push_back(x: value);
1850	stack.back().SetValueType(Value::ValueType::LoadAddress);
1851	} else {
1852	return llvm::createStringError(
1853	Fmt: "invalid stack frame in context for DW_OP_fbreg opcode");
1854	}
1855	} else {
1856	return llvm::createStringError(
1857	Fmt: "NULL execution context for DW_OP_fbreg");
1858	}
1859
1860	break;
1861
1862	// OPCODE: DW_OP_nop
1863	// OPERANDS: none
1864	// DESCRIPTION: A place holder. It has no effect on the location stack
1865	// or any of its values.
1866	case DW_OP_nop:
1867	break;
1868
1869	// OPCODE: DW_OP_piece
1870	// OPERANDS: 1
1871	// ULEB128: byte size of the piece
1872	// DESCRIPTION: The operand describes the size in bytes of the piece of
1873	// the object referenced by the DWARF expression whose result is at the top
1874	// of the stack. If the piece is located in a register, but does not occupy
1875	// the entire register, the placement of the piece within that register is
1876	// defined by the ABI.
1877	//
1878	// Many compilers store a single variable in sets of registers, or store a
1879	// variable partially in memory and partially in registers. DW_OP_piece
1880	// provides a way of describing how large a part of a variable a particular
1881	// DWARF expression refers to.
1882	case DW_OP_piece: {
1883	LocationDescriptionKind piece_locdesc = dwarf4_location_description_kind;
1884	// Reset for the next piece.
1885	dwarf4_location_description_kind = Memory;
1886
1887	const uint64_t piece_byte_size = opcodes.GetULEB128(offset_ptr: &offset);
1888
1889	if (piece_byte_size > 0) {
1890	Value curr_piece;
1891
1892	if (stack.empty()) {
1893	UpdateValueTypeFromLocationDescription(
1894	log, dwarf_cu, kind: LocationDescriptionKind::Empty);
1895	// In a multi-piece expression, this means that the current piece is
1896	// not available. Fill with zeros for now by resizing the data and
1897	// appending it
1898	curr_piece.ResizeData(len: piece_byte_size);
1899	// Note that "0" is not a correct value for the unknown bits.
1900	// It would be better to also return a mask of valid bits together
1901	// with the expression result, so the debugger can print missing
1902	// members as "<optimized out>" or something.
1903	::memset(s: curr_piece.GetBuffer().GetBytes(), c: 0, n: piece_byte_size);
1904	pieces.AppendDataToHostBuffer(rhs: curr_piece);
1905	} else {
1906	Status error;
1907	// Extract the current piece into "curr_piece"
1908	Value curr_piece_source_value(stack.back());
1909	stack.pop_back();
1910	UpdateValueTypeFromLocationDescription(log, dwarf_cu, kind: piece_locdesc,
1911	value: &curr_piece_source_value);
1912
1913	const Value::ValueType curr_piece_source_value_type =
1914	curr_piece_source_value.GetValueType();
1915	Scalar &scalar = curr_piece_source_value.GetScalar();
1916	lldb::addr_t addr = scalar.ULongLong(LLDB_INVALID_ADDRESS);
1917	switch (curr_piece_source_value_type) {
1918	case Value::ValueType::Invalid:
1919	return llvm::createStringError(Fmt: "invalid value type");
1920	case Value::ValueType::FileAddress:
1921	if (target) {
1922	curr_piece_source_value.ConvertToLoadAddress(module: module_sp.get(),
1923	target);
1924	addr = scalar.ULongLong(LLDB_INVALID_ADDRESS);
1925	} else {
1926	return llvm::createStringError(
1927	Fmt: "unable to convert file address 0x%" PRIx64
1928	" to load address "
1929	"for DW_OP_piece(%" PRIu64 "): "
1930	"no target available",
1931	Vals: addr, Vals: piece_byte_size);
1932	}
1933	[[fallthrough]];
1934	case Value::ValueType::LoadAddress: {
1935	if (target) {
1936	if (curr_piece.ResizeData(len: piece_byte_size) == piece_byte_size) {
1937	if (target->ReadMemory(addr, dst: curr_piece.GetBuffer().GetBytes(),
1938	dst_len: piece_byte_size, error,
1939	/*force_live_memory=*/false) !=
1940	piece_byte_size) {
1941	const char *addr_type = (curr_piece_source_value_type ==
1942	Value::ValueType::LoadAddress)
1943	? "load"
1944	: "file";
1945	return llvm::createStringError(
1946	Fmt: "failed to read memory DW_OP_piece(%" PRIu64
1947	") from %s address 0x%" PRIx64,
1948	Vals: piece_byte_size, Vals: addr_type, Vals: addr);
1949	}
1950	} else {
1951	return llvm::createStringError(
1952	Fmt: "failed to resize the piece memory buffer for "
1953	"DW_OP_piece(%" PRIu64 ")",
1954	Vals: piece_byte_size);
1955	}
1956	}
1957	} break;
1958	case Value::ValueType::HostAddress: {
1959	return llvm::createStringError(
1960	Fmt: "failed to read memory DW_OP_piece(%" PRIu64
1961	") from host address 0x%" PRIx64,
1962	Vals: piece_byte_size, Vals: addr);
1963	} break;
1964
1965	case Value::ValueType::Scalar: {
1966	uint32_t bit_size = piece_byte_size * 8;
1967	uint32_t bit_offset = 0;
1968	if (!scalar.ExtractBitfield(
1969	bit_size, bit_offset)) {
1970	return llvm::createStringError(
1971	Fmt: "unable to extract %" PRIu64 " bytes from a %" PRIu64
1972	" byte scalar value.",
1973	Vals: piece_byte_size,
1974	Vals: (uint64_t)curr_piece_source_value.GetScalar().GetByteSize());
1975	}
1976	// Create curr_piece with bit_size. By default Scalar
1977	// grows to the nearest host integer type.
1978	llvm::APInt fail_value(1, 0, false);
1979	llvm::APInt ap_int = scalar.UInt128(fail_value);
1980	assert(ap_int.getBitWidth() >= bit_size);
1981	llvm::ArrayRef<uint64_t> buf{ap_int.getRawData(),
1982	ap_int.getNumWords()};
1983	curr_piece.GetScalar() = Scalar(llvm::APInt(bit_size, buf));
1984	} break;
1985	}
1986
1987	// Check if this is the first piece?
1988	if (op_piece_offset == 0) {
1989	// This is the first piece, we should push it back onto the stack
1990	// so subsequent pieces will be able to access this piece and add
1991	// to it.
1992	if (pieces.AppendDataToHostBuffer(rhs: curr_piece) == 0) {
1993	return llvm::createStringError(Fmt: "failed to append piece data");
1994	}
1995	} else {
1996	// If this is the second or later piece there should be a value on
1997	// the stack.
1998	if (pieces.GetBuffer().GetByteSize() != op_piece_offset) {
1999	return llvm::createStringError(
2000	Fmt: "DW_OP_piece for offset %" PRIu64
2001	" but top of stack is of size %" PRIu64,
2002	Vals: op_piece_offset, Vals: pieces.GetBuffer().GetByteSize());
2003	}
2004
2005	if (pieces.AppendDataToHostBuffer(rhs: curr_piece) == 0)
2006	return llvm::createStringError(Fmt: "failed to append piece data");
2007	}
2008	}
2009	op_piece_offset += piece_byte_size;
2010	}
2011	} break;
2012
2013	case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
2014	if (stack.size() < 1) {
2015	UpdateValueTypeFromLocationDescription(log, dwarf_cu,
2016	kind: LocationDescriptionKind::Empty);
2017	// Reset for the next piece.
2018	dwarf4_location_description_kind = Memory;
2019	return llvm::createStringError(
2020	Fmt: "expression stack needs at least 1 item for DW_OP_bit_piece");
2021	} else {
2022	UpdateValueTypeFromLocationDescription(
2023	log, dwarf_cu, kind: dwarf4_location_description_kind, value: &stack.back());
2024	// Reset for the next piece.
2025	dwarf4_location_description_kind = Memory;
2026	const uint64_t piece_bit_size = opcodes.GetULEB128(offset_ptr: &offset);
2027	const uint64_t piece_bit_offset = opcodes.GetULEB128(offset_ptr: &offset);
2028	switch (stack.back().GetValueType()) {
2029	case Value::ValueType::Invalid:
2030	return llvm::createStringError(
2031	Fmt: "unable to extract bit value from invalid value");
2032	case Value::ValueType::Scalar: {
2033	if (!stack.back().GetScalar().ExtractBitfield(bit_size: piece_bit_size,
2034	bit_offset: piece_bit_offset)) {
2035	return llvm::createStringError(
2036	Fmt: "unable to extract %" PRIu64 " bit value with %" PRIu64
2037	" bit offset from a %" PRIu64 " bit scalar value.",
2038	Vals: piece_bit_size, Vals: piece_bit_offset,
2039	Vals: (uint64_t)(stack.back().GetScalar().GetByteSize() * 8));
2040	}
2041	} break;
2042
2043	case Value::ValueType::FileAddress:
2044	case Value::ValueType::LoadAddress:
2045	case Value::ValueType::HostAddress:
2046	return llvm::createStringError(
2047	Fmt: "unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
2048	", bit_offset = %" PRIu64 ") from an address value.",
2049	Vals: piece_bit_size, Vals: piece_bit_offset);
2050	}
2051	}
2052	break;
2053
2054	// OPCODE: DW_OP_implicit_value
2055	// OPERANDS: 2
2056	// ULEB128 size of the value block in bytes
2057	// uint8_t* block bytes encoding value in target's memory
2058	// representation
2059	// DESCRIPTION: Value is immediately stored in block in the debug info with
2060	// the memory representation of the target.
2061	case DW_OP_implicit_value: {
2062	dwarf4_location_description_kind = Implicit;
2063
2064	const uint32_t len = opcodes.GetULEB128(offset_ptr: &offset);
2065	const void *data = opcodes.GetData(offset_ptr: &offset, length: len);
2066
2067	if (!data) {
2068	LLDB_LOG(log, "Evaluate_DW_OP_implicit_value: could not be read data");
2069	return llvm::createStringError(Fmt: "could not evaluate %s",
2070	Vals: DW_OP_value_to_name(val: op));
2071	}
2072
2073	Value result(data, len);
2074	stack.push_back(x: result);
2075	break;
2076	}
2077
2078	case DW_OP_implicit_pointer: {
2079	dwarf4_location_description_kind = Implicit;
2080	return llvm::createStringError(Fmt: "Could not evaluate %s.",
2081	Vals: DW_OP_value_to_name(val: op));
2082	}
2083
2084	// OPCODE: DW_OP_push_object_address
2085	// OPERANDS: none
2086	// DESCRIPTION: Pushes the address of the object currently being
2087	// evaluated as part of evaluation of a user presented expression. This
2088	// object may correspond to an independent variable described by its own
2089	// DIE or it may be a component of an array, structure, or class whose
2090	// address has been dynamically determined by an earlier step during user
2091	// expression evaluation.
2092	case DW_OP_push_object_address:
2093	if (object_address_ptr)
2094	stack.push_back(x: *object_address_ptr);
2095	else {
2096	return llvm::createStringError(Fmt: "DW_OP_push_object_address used without "
2097	"specifying an object address");
2098	}
2099	break;
2100
2101	// OPCODE: DW_OP_call2
2102	// OPERANDS:
2103	// uint16_t compile unit relative offset of a DIE
2104	// DESCRIPTION: Performs subroutine calls during evaluation
2105	// of a DWARF expression. The operand is the 2-byte unsigned offset of a
2106	// debugging information entry in the current compilation unit.
2107	//
2108	// Operand interpretation is exactly like that for DW_FORM_ref2.
2109	//
2110	// This operation transfers control of DWARF expression evaluation to the
2111	// DW_AT_location attribute of the referenced DIE. If there is no such
2112	// attribute, then there is no effect. Execution of the DWARF expression of
2113	// a DW_AT_location attribute may add to and/or remove from values on the
2114	// stack. Execution returns to the point following the call when the end of
2115	// the attribute is reached. Values on the stack at the time of the call
2116	// may be used as parameters by the called expression and values left on
2117	// the stack by the called expression may be used as return values by prior
2118	// agreement between the calling and called expressions.
2119	case DW_OP_call2:
2120	return llvm::createStringError(Fmt: "unimplemented opcode DW_OP_call2");
2121	// OPCODE: DW_OP_call4
2122	// OPERANDS: 1
2123	// uint32_t compile unit relative offset of a DIE
2124	// DESCRIPTION: Performs a subroutine call during evaluation of a DWARF
2125	// expression. For DW_OP_call4, the operand is a 4-byte unsigned offset of
2126	// a debugging information entry in the current compilation unit.
2127	//
2128	// Operand interpretation DW_OP_call4 is exactly like that for
2129	// DW_FORM_ref4.
2130	//
2131	// This operation transfers control of DWARF expression evaluation to the
2132	// DW_AT_location attribute of the referenced DIE. If there is no such
2133	// attribute, then there is no effect. Execution of the DWARF expression of
2134	// a DW_AT_location attribute may add to and/or remove from values on the
2135	// stack. Execution returns to the point following the call when the end of
2136	// the attribute is reached. Values on the stack at the time of the call
2137	// may be used as parameters by the called expression and values left on
2138	// the stack by the called expression may be used as return values by prior
2139	// agreement between the calling and called expressions.
2140	case DW_OP_call4:
2141	return llvm::createStringError(Fmt: "unimplemented opcode DW_OP_call4");
2142
2143	// OPCODE: DW_OP_stack_value
2144	// OPERANDS: None
2145	// DESCRIPTION: Specifies that the object does not exist in memory but
2146	// rather is a constant value. The value from the top of the stack is the
2147	// value to be used. This is the actual object value and not the location.
2148	case DW_OP_stack_value:
2149	dwarf4_location_description_kind = Implicit;
2150	stack.back().SetValueType(Value::ValueType::Scalar);
2151	break;
2152
2153	// OPCODE: DW_OP_convert
2154	// OPERANDS: 1
2155	// A ULEB128 that is either a DIE offset of a
2156	// DW_TAG_base_type or 0 for the generic (pointer-sized) type.
2157	//
2158	// DESCRIPTION: Pop the top stack element, convert it to a
2159	// different type, and push the result.
2160	case DW_OP_convert: {
2161	const uint64_t relative_die_offset = opcodes.GetULEB128(offset_ptr: &offset);
2162	uint64_t bit_size;
2163	bool sign;
2164	if (relative_die_offset == 0) {
2165	// The generic type has the size of an address on the target
2166	// machine and an unspecified signedness. Scalar has no
2167	// "unspecified signedness", so we use unsigned types.
2168	if (!module_sp)
2169	return llvm::createStringError(Fmt: "no module");
2170	sign = false;
2171	bit_size = module_sp->GetArchitecture().GetAddressByteSize() * 8;
2172	if (!bit_size)
2173	return llvm::createStringError(Fmt: "unspecified architecture");
2174	} else {
2175	auto bit_size_sign_or_err =
2176	dwarf_cu->GetDIEBitSizeAndSign(relative_die_offset);
2177	if (!bit_size_sign_or_err)
2178	return bit_size_sign_or_err.takeError();
2179	bit_size = bit_size_sign_or_err->first;
2180	sign = bit_size_sign_or_err->second;
2181	}
2182	Scalar &top = stack.back().ResolveValue(exe_ctx);
2183	top.TruncOrExtendTo(bits: bit_size, sign);
2184	break;
2185	}
2186
2187	// OPCODE: DW_OP_call_frame_cfa
2188	// OPERANDS: None
2189	// DESCRIPTION: Specifies a DWARF expression that pushes the value of
2190	// the canonical frame address consistent with the call frame information
2191	// located in .debug_frame (or in the FDEs of the eh_frame section).
2192	case DW_OP_call_frame_cfa:
2193	if (frame) {
2194	// Note that we don't have to parse FDEs because this DWARF expression
2195	// is commonly evaluated with a valid stack frame.
2196	StackID id = frame->GetStackID();
2197	addr_t cfa = id.GetCallFrameAddress();
2198	if (cfa != LLDB_INVALID_ADDRESS) {
2199	stack.push_back(x: Scalar(cfa));
2200	stack.back().SetValueType(Value::ValueType::LoadAddress);
2201	} else {
2202	return llvm::createStringError(
2203	Fmt: "stack frame does not include a canonical "
2204	"frame address for DW_OP_call_frame_cfa "
2205	"opcode");
2206	}
2207	} else {
2208	return llvm::createStringError(Fmt: "unvalid stack frame in context for "
2209	"DW_OP_call_frame_cfa opcode");
2210	}
2211	break;
2212
2213	// OPCODE: DW_OP_form_tls_address (or the old pre-DWARFv3 vendor extension
2214	// opcode, DW_OP_GNU_push_tls_address)
2215	// OPERANDS: none
2216	// DESCRIPTION: Pops a TLS offset from the stack, converts it to
2217	// an address in the current thread's thread-local storage block, and
2218	// pushes it on the stack.
2219	case DW_OP_form_tls_address:
2220	case DW_OP_GNU_push_tls_address: {
2221	if (stack.size() < 1) {
2222	if (op == DW_OP_form_tls_address)
2223	return llvm::createStringError(
2224	Fmt: "DW_OP_form_tls_address needs an argument");
2225	else
2226	return llvm::createStringError(
2227	Fmt: "DW_OP_GNU_push_tls_address needs an argument");
2228	}
2229
2230	if (!exe_ctx || !module_sp)
2231	return llvm::createStringError(Fmt: "no context to evaluate TLS within");
2232
2233	Thread *thread = exe_ctx->GetThreadPtr();
2234	if (!thread)
2235	return llvm::createStringError(Fmt: "no thread to evaluate TLS within");
2236
2237	// Lookup the TLS block address for this thread and module.
2238	const addr_t tls_file_addr =
2239	stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
2240	const addr_t tls_load_addr =
2241	thread->GetThreadLocalData(module: module_sp, tls_file_addr);
2242
2243	if (tls_load_addr == LLDB_INVALID_ADDRESS)
2244	return llvm::createStringError(
2245	Fmt: "no TLS data currently exists for this thread");
2246
2247	stack.back().GetScalar() = tls_load_addr;
2248	stack.back().SetValueType(Value::ValueType::LoadAddress);
2249	} break;
2250
2251	// OPCODE: DW_OP_addrx (DW_OP_GNU_addr_index is the legacy name.)
2252	// OPERANDS: 1
2253	// ULEB128: index to the .debug_addr section
2254	// DESCRIPTION: Pushes an address to the stack from the .debug_addr
2255	// section with the base address specified by the DW_AT_addr_base attribute
2256	// and the 0 based index is the ULEB128 encoded index.
2257	case DW_OP_addrx:
2258	case DW_OP_GNU_addr_index: {
2259	if (!dwarf_cu)
2260	return llvm::createStringError(Fmt: "DW_OP_GNU_addr_index found without a "
2261	"compile unit being specified");
2262	uint64_t index = opcodes.GetULEB128(offset_ptr: &offset);
2263	lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index);
2264	stack.push_back(x: Scalar(value));
2265	if (target &&
2266	target->GetArchitecture().GetCore() == ArchSpec::eCore_wasm32) {
2267	// wasm file sections aren't mapped into memory, therefore addresses can
2268	// never point into a file section and are always LoadAddresses.
2269	stack.back().SetValueType(Value::ValueType::LoadAddress);
2270	} else {
2271	stack.back().SetValueType(Value::ValueType::FileAddress);
2272	}
2273	} break;
2274
2275	// OPCODE: DW_OP_GNU_const_index
2276	// OPERANDS: 1
2277	// ULEB128: index to the .debug_addr section
2278	// DESCRIPTION: Pushes an constant with the size of a machine address to
2279	// the stack from the .debug_addr section with the base address specified
2280	// by the DW_AT_addr_base attribute and the 0 based index is the ULEB128
2281	// encoded index.
2282	case DW_OP_GNU_const_index: {
2283	if (!dwarf_cu) {
2284	return llvm::createStringError(Fmt: "DW_OP_GNU_const_index found without a "
2285	"compile unit being specified");
2286	}
2287	uint64_t index = opcodes.GetULEB128(offset_ptr: &offset);
2288	lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index);
2289	stack.push_back(x: Scalar(value));
2290	} break;
2291
2292	case DW_OP_GNU_entry_value:
2293	case DW_OP_entry_value: {
2294	if (llvm::Error err = Evaluate_DW_OP_entry_value(stack, exe_ctx, reg_ctx,
2295	opcodes, opcode_offset&: offset, log))
2296	return llvm::createStringError(
2297	Fmt: "could not evaluate DW_OP_entry_value: %s",
2298	Vals: llvm::toString(E: std::move(err)).c_str());
2299	break;
2300	}
2301
2302	default:
2303	if (dwarf_cu) {
2304	if (dwarf_cu->ParseVendorDWARFOpcode(op, opcodes, offset, stack)) {
2305	break;
2306	}
2307	}
2308	return llvm::createStringError(S: llvm::formatv(
2309	Fmt: "Unhandled opcode {0} in DWARFExpression", Vals: LocationAtom(op)));
2310	}
2311	}
2312
2313	if (stack.empty()) {
2314	// Nothing on the stack, check if we created a piece value from DW_OP_piece
2315	// or DW_OP_bit_piece opcodes
2316	if (pieces.GetBuffer().GetByteSize())
2317	return pieces;
2318
2319	return llvm::createStringError(Fmt: "stack empty after evaluation");
2320	}
2321
2322	UpdateValueTypeFromLocationDescription(
2323	log, dwarf_cu, kind: dwarf4_location_description_kind, value: &stack.back());
2324
2325	if (log && log->GetVerbose()) {
2326	size_t count = stack.size();
2327	LLDB_LOGF(log,
2328	"Stack after operation has %" PRIu64 " values:", (uint64_t)count);
2329	for (size_t i = 0; i < count; ++i) {
2330	StreamString new_value;
2331	new_value.Printf(format: "[%" PRIu64 "]", (uint64_t)i);
2332	stack[i].Dump(strm: &new_value);
2333	LLDB_LOGF(log, " %s", new_value.GetData());
2334	}
2335	}
2336	return stack.back();
2337	}
2338
2339	bool DWARFExpression::MatchesOperand(
2340	StackFrame &frame, const Instruction::Operand &operand) const {
2341	using namespace OperandMatchers;
2342
2343	RegisterContextSP reg_ctx_sp = frame.GetRegisterContext();
2344	if (!reg_ctx_sp) {
2345	return false;
2346	}
2347
2348	DataExtractor opcodes(m_data);
2349
2350	lldb::offset_t op_offset = 0;
2351	uint8_t opcode = opcodes.GetU8(offset_ptr: &op_offset);
2352
2353	if (opcode == DW_OP_fbreg) {
2354	int64_t offset = opcodes.GetSLEB128(offset_ptr: &op_offset);
2355
2356	DWARFExpressionList *fb_expr = frame.GetFrameBaseExpression(error_ptr: nullptr);
2357	if (!fb_expr) {
2358	return false;
2359	}
2360
2361	auto recurse = [&frame, fb_expr](const Instruction::Operand &child) {
2362	return fb_expr->MatchesOperand(frame, operand: child);
2363	};
2364
2365	if (!offset &&
2366	MatchUnaryOp(base: MatchOpType(type: Instruction::Operand::Type::Dereference),
2367	child: recurse)(operand)) {
2368	return true;
2369	}
2370
2371	return MatchUnaryOp(
2372	base: MatchOpType(type: Instruction::Operand::Type::Dereference),
2373	child: MatchBinaryOp(base: MatchOpType(type: Instruction::Operand::Type::Sum),
2374	left: MatchImmOp(imm: offset), right: recurse))(operand);
2375	}
2376
2377	bool dereference = false;
2378	const RegisterInfo *reg = nullptr;
2379	int64_t offset = 0;
2380
2381	if (opcode >= DW_OP_reg0 && opcode <= DW_OP_reg31) {
2382	reg = reg_ctx_sp->GetRegisterInfo(reg_kind: m_reg_kind, reg_num: opcode - DW_OP_reg0);
2383	} else if (opcode >= DW_OP_breg0 && opcode <= DW_OP_breg31) {
2384	offset = opcodes.GetSLEB128(offset_ptr: &op_offset);
2385	reg = reg_ctx_sp->GetRegisterInfo(reg_kind: m_reg_kind, reg_num: opcode - DW_OP_breg0);
2386	} else if (opcode == DW_OP_regx) {
2387	uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(offset_ptr: &op_offset));
2388	reg = reg_ctx_sp->GetRegisterInfo(reg_kind: m_reg_kind, reg_num);
2389	} else if (opcode == DW_OP_bregx) {
2390	uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(offset_ptr: &op_offset));
2391	offset = opcodes.GetSLEB128(offset_ptr: &op_offset);
2392	reg = reg_ctx_sp->GetRegisterInfo(reg_kind: m_reg_kind, reg_num);
2393	} else {
2394	return false;
2395	}
2396
2397	if (!reg) {
2398	return false;
2399	}
2400
2401	if (dereference) {
2402	if (!offset &&
2403	MatchUnaryOp(base: MatchOpType(type: Instruction::Operand::Type::Dereference),
2404	child: MatchRegOp(info: *reg))(operand)) {
2405	return true;
2406	}
2407
2408	return MatchUnaryOp(
2409	base: MatchOpType(type: Instruction::Operand::Type::Dereference),
2410	child: MatchBinaryOp(base: MatchOpType(type: Instruction::Operand::Type::Sum),
2411	left: MatchRegOp(info: *reg),
2412	right: MatchImmOp(imm: offset)))(operand);
2413	} else {
2414	return MatchRegOp(info: *reg)(operand);
2415	}
2416	}
2417