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 "llvm/DebugInfo/DWARF/DWARFExpression.h"
10 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
11 #include "llvm/MC/MCRegisterInfo.h"
12 #include "llvm/Support/Format.h"
13 #include <cassert>
14 #include <cstdint>
15 #include <vector>
16 
17 using namespace llvm;
18 using namespace dwarf;
19 
20 namespace llvm {
21 
22 typedef std::vector<DWARFExpression::Operation::Description> DescVector;
23 
24 static DescVector getDescriptions() {
25   DescVector Descriptions;
26   typedef DWARFExpression::Operation Op;
27   typedef Op::Description Desc;
28 
29   Descriptions.resize(0xff);
30   Descriptions[DW_OP_addr] = Desc(Op::Dwarf2, Op::SizeAddr);
31   Descriptions[DW_OP_deref] = Desc(Op::Dwarf2);
32   Descriptions[DW_OP_const1u] = Desc(Op::Dwarf2, Op::Size1);
33   Descriptions[DW_OP_const1s] = Desc(Op::Dwarf2, Op::SignedSize1);
34   Descriptions[DW_OP_const2u] = Desc(Op::Dwarf2, Op::Size2);
35   Descriptions[DW_OP_const2s] = Desc(Op::Dwarf2, Op::SignedSize2);
36   Descriptions[DW_OP_const4u] = Desc(Op::Dwarf2, Op::Size4);
37   Descriptions[DW_OP_const4s] = Desc(Op::Dwarf2, Op::SignedSize4);
38   Descriptions[DW_OP_const8u] = Desc(Op::Dwarf2, Op::Size8);
39   Descriptions[DW_OP_const8s] = Desc(Op::Dwarf2, Op::SignedSize8);
40   Descriptions[DW_OP_constu] = Desc(Op::Dwarf2, Op::SizeLEB);
41   Descriptions[DW_OP_consts] = Desc(Op::Dwarf2, Op::SignedSizeLEB);
42   Descriptions[DW_OP_dup] = Desc(Op::Dwarf2);
43   Descriptions[DW_OP_drop] = Desc(Op::Dwarf2);
44   Descriptions[DW_OP_over] = Desc(Op::Dwarf2);
45   Descriptions[DW_OP_pick] = Desc(Op::Dwarf2, Op::Size1);
46   Descriptions[DW_OP_swap] = Desc(Op::Dwarf2);
47   Descriptions[DW_OP_rot] = Desc(Op::Dwarf2);
48   Descriptions[DW_OP_xderef] = Desc(Op::Dwarf2);
49   Descriptions[DW_OP_abs] = Desc(Op::Dwarf2);
50   Descriptions[DW_OP_and] = Desc(Op::Dwarf2);
51   Descriptions[DW_OP_div] = Desc(Op::Dwarf2);
52   Descriptions[DW_OP_minus] = Desc(Op::Dwarf2);
53   Descriptions[DW_OP_mod] = Desc(Op::Dwarf2);
54   Descriptions[DW_OP_mul] = Desc(Op::Dwarf2);
55   Descriptions[DW_OP_neg] = Desc(Op::Dwarf2);
56   Descriptions[DW_OP_not] = Desc(Op::Dwarf2);
57   Descriptions[DW_OP_or] = Desc(Op::Dwarf2);
58   Descriptions[DW_OP_plus] = Desc(Op::Dwarf2);
59   Descriptions[DW_OP_plus_uconst] = Desc(Op::Dwarf2, Op::SizeLEB);
60   Descriptions[DW_OP_shl] = Desc(Op::Dwarf2);
61   Descriptions[DW_OP_shr] = Desc(Op::Dwarf2);
62   Descriptions[DW_OP_shra] = Desc(Op::Dwarf2);
63   Descriptions[DW_OP_xor] = Desc(Op::Dwarf2);
64   Descriptions[DW_OP_skip] = Desc(Op::Dwarf2, Op::SignedSize2);
65   Descriptions[DW_OP_bra] = Desc(Op::Dwarf2, Op::SignedSize2);
66   Descriptions[DW_OP_eq] = Desc(Op::Dwarf2);
67   Descriptions[DW_OP_ge] = Desc(Op::Dwarf2);
68   Descriptions[DW_OP_gt] = Desc(Op::Dwarf2);
69   Descriptions[DW_OP_le] = Desc(Op::Dwarf2);
70   Descriptions[DW_OP_lt] = Desc(Op::Dwarf2);
71   Descriptions[DW_OP_ne] = Desc(Op::Dwarf2);
72   for (uint16_t LA = DW_OP_lit0; LA <= DW_OP_lit31; ++LA)
73     Descriptions[LA] = Desc(Op::Dwarf2);
74   for (uint16_t LA = DW_OP_reg0; LA <= DW_OP_reg31; ++LA)
75     Descriptions[LA] = Desc(Op::Dwarf2);
76   for (uint16_t LA = DW_OP_breg0; LA <= DW_OP_breg31; ++LA)
77     Descriptions[LA] = Desc(Op::Dwarf2, Op::SignedSizeLEB);
78   Descriptions[DW_OP_regx] = Desc(Op::Dwarf2, Op::SizeLEB);
79   Descriptions[DW_OP_fbreg] = Desc(Op::Dwarf2, Op::SignedSizeLEB);
80   Descriptions[DW_OP_bregx] = Desc(Op::Dwarf2, Op::SizeLEB, Op::SignedSizeLEB);
81   Descriptions[DW_OP_piece] = Desc(Op::Dwarf2, Op::SizeLEB);
82   Descriptions[DW_OP_deref_size] = Desc(Op::Dwarf2, Op::Size1);
83   Descriptions[DW_OP_xderef_size] = Desc(Op::Dwarf2, Op::Size1);
84   Descriptions[DW_OP_nop] = Desc(Op::Dwarf2);
85   Descriptions[DW_OP_push_object_address] = Desc(Op::Dwarf3);
86   Descriptions[DW_OP_call2] = Desc(Op::Dwarf3, Op::Size2);
87   Descriptions[DW_OP_call4] = Desc(Op::Dwarf3, Op::Size4);
88   Descriptions[DW_OP_call_ref] = Desc(Op::Dwarf3, Op::SizeRefAddr);
89   Descriptions[DW_OP_form_tls_address] = Desc(Op::Dwarf3);
90   Descriptions[DW_OP_call_frame_cfa] = Desc(Op::Dwarf3);
91   Descriptions[DW_OP_bit_piece] = Desc(Op::Dwarf3, Op::SizeLEB, Op::SizeLEB);
92   Descriptions[DW_OP_implicit_value] =
93       Desc(Op::Dwarf3, Op::SizeLEB, Op::SizeBlock);
94   Descriptions[DW_OP_stack_value] = Desc(Op::Dwarf3);
95   Descriptions[DW_OP_WASM_location] =
96       Desc(Op::Dwarf4, Op::SizeLEB, Op::WasmLocationArg);
97   Descriptions[DW_OP_GNU_push_tls_address] = Desc(Op::Dwarf3);
98   Descriptions[DW_OP_addrx] = Desc(Op::Dwarf4, Op::SizeLEB);
99   Descriptions[DW_OP_GNU_addr_index] = Desc(Op::Dwarf4, Op::SizeLEB);
100   Descriptions[DW_OP_GNU_const_index] = Desc(Op::Dwarf4, Op::SizeLEB);
101   Descriptions[DW_OP_GNU_entry_value] = Desc(Op::Dwarf4, Op::SizeLEB);
102 
103   Descriptions[DW_OP_convert] = Desc(Op::Dwarf5, Op::BaseTypeRef);
104   Descriptions[DW_OP_entry_value] = Desc(Op::Dwarf5, Op::SizeLEB);
105   Descriptions[DW_OP_regval_type] =
106       Desc(Op::Dwarf5, Op::SizeLEB, Op::BaseTypeRef);
107 
108   return Descriptions;
109 }
110 
111 static DWARFExpression::Operation::Description getOpDesc(unsigned OpCode) {
112   // FIXME: Make this constexpr once all compilers are smart enough to do it.
113   static DescVector Descriptions = getDescriptions();
114   // Handle possible corrupted or unsupported operation.
115   if (OpCode >= Descriptions.size())
116     return {};
117   return Descriptions[OpCode];
118 }
119 
120 bool DWARFExpression::Operation::extract(DataExtractor Data,
121                                          uint8_t AddressSize, uint64_t Offset,
122                                          Optional<DwarfFormat> Format) {
123   Opcode = Data.getU8(&Offset);
124 
125   Desc = getOpDesc(Opcode);
126   if (Desc.Version == Operation::DwarfNA) {
127     EndOffset = Offset;
128     return false;
129   }
130 
131   for (unsigned Operand = 0; Operand < 2; ++Operand) {
132     unsigned Size = Desc.Op[Operand];
133     unsigned Signed = Size & Operation::SignBit;
134 
135     if (Size == Operation::SizeNA)
136       break;
137 
138     EndOffset = Offset;
139     switch (Size & ~Operation::SignBit) {
140     case Operation::Size1:
141       Operands[Operand] = Data.getU8(&Offset);
142       if (Signed)
143         Operands[Operand] = (int8_t)Operands[Operand];
144       break;
145     case Operation::Size2:
146       Operands[Operand] = Data.getU16(&Offset);
147       if (Signed)
148         Operands[Operand] = (int16_t)Operands[Operand];
149       break;
150     case Operation::Size4:
151       Operands[Operand] = Data.getU32(&Offset);
152       if (Signed)
153         Operands[Operand] = (int32_t)Operands[Operand];
154       break;
155     case Operation::Size8:
156       Operands[Operand] = Data.getU64(&Offset);
157       break;
158     case Operation::SizeAddr:
159       Operands[Operand] = Data.getUnsigned(&Offset, AddressSize);
160       break;
161     case Operation::SizeRefAddr:
162       if (!Format)
163         return false;
164       Operands[Operand] =
165           Data.getUnsigned(&Offset, dwarf::getDwarfOffsetByteSize(*Format));
166       break;
167     case Operation::SizeLEB:
168       if (Signed)
169         Operands[Operand] = Data.getSLEB128(&Offset);
170       else
171         Operands[Operand] = Data.getULEB128(&Offset);
172       break;
173     case Operation::BaseTypeRef:
174       Operands[Operand] = Data.getULEB128(&Offset);
175       break;
176     case Operation::WasmLocationArg:
177       assert(Operand == 1);
178       switch (Operands[0]) {
179       case 0: case 1: case 2:
180         Operands[Operand] = Data.getULEB128(&Offset);
181         break;
182       case 3: // global as uint32
183          Operands[Operand] = Data.getU32(&Offset);
184          break;
185       default:
186         return false; // Unknown Wasm location
187       }
188       break;
189     case Operation::SizeBlock:
190       // We need a size, so this cannot be the first operand
191       if (Operand == 0)
192         return false;
193       // Store the offset of the block as the value.
194       Operands[Operand] = Offset;
195       Offset += Operands[Operand - 1];
196       break;
197     default:
198       llvm_unreachable("Unknown DWARFExpression Op size");
199     }
200 
201     OperandEndOffsets[Operand] = Offset;
202   }
203 
204   EndOffset = Offset;
205   return true;
206 }
207 
208 static void prettyPrintBaseTypeRef(DWARFUnit *U, raw_ostream &OS,
209                                    uint64_t Operands[2], unsigned Operand) {
210   assert(Operand < 2 && "operand out of bounds");
211   auto Die = U->getDIEForOffset(U->getOffset() + Operands[Operand]);
212   if (Die && Die.getTag() == dwarf::DW_TAG_base_type) {
213     OS << format(" (0x%08" PRIx64 ")", U->getOffset() + Operands[Operand]);
214     if (auto Name = Die.find(dwarf::DW_AT_name))
215       OS << " \"" << Name->getAsCString() << "\"";
216   } else {
217     OS << format(" <invalid base_type ref: 0x%" PRIx64 ">",
218                  Operands[Operand]);
219   }
220 }
221 
222 static bool prettyPrintRegisterOp(DWARFUnit *U, raw_ostream &OS, uint8_t Opcode,
223                                   uint64_t Operands[2],
224                                   const MCRegisterInfo *MRI, bool isEH) {
225   if (!MRI)
226     return false;
227 
228   uint64_t DwarfRegNum;
229   unsigned OpNum = 0;
230 
231   if (Opcode == DW_OP_bregx || Opcode == DW_OP_regx ||
232       Opcode == DW_OP_regval_type)
233     DwarfRegNum = Operands[OpNum++];
234   else if (Opcode >= DW_OP_breg0 && Opcode < DW_OP_bregx)
235     DwarfRegNum = Opcode - DW_OP_breg0;
236   else
237     DwarfRegNum = Opcode - DW_OP_reg0;
238 
239   if (Optional<unsigned> LLVMRegNum = MRI->getLLVMRegNum(DwarfRegNum, isEH)) {
240     if (const char *RegName = MRI->getName(*LLVMRegNum)) {
241       if ((Opcode >= DW_OP_breg0 && Opcode <= DW_OP_breg31) ||
242           Opcode == DW_OP_bregx)
243         OS << format(" %s%+" PRId64, RegName, Operands[OpNum]);
244       else
245         OS << ' ' << RegName;
246 
247       if (Opcode == DW_OP_regval_type)
248         prettyPrintBaseTypeRef(U, OS, Operands, 1);
249       return true;
250     }
251   }
252 
253   return false;
254 }
255 
256 bool DWARFExpression::Operation::print(raw_ostream &OS,
257                                        const DWARFExpression *Expr,
258                                        const MCRegisterInfo *RegInfo,
259                                        DWARFUnit *U,
260                                        bool isEH) {
261   if (Error) {
262     OS << "<decoding error>";
263     return false;
264   }
265 
266   StringRef Name = OperationEncodingString(Opcode);
267   assert(!Name.empty() && "DW_OP has no name!");
268   OS << Name;
269 
270   if ((Opcode >= DW_OP_breg0 && Opcode <= DW_OP_breg31) ||
271       (Opcode >= DW_OP_reg0 && Opcode <= DW_OP_reg31) ||
272       Opcode == DW_OP_bregx || Opcode == DW_OP_regx ||
273       Opcode == DW_OP_regval_type)
274     if (prettyPrintRegisterOp(U, OS, Opcode, Operands, RegInfo, isEH))
275       return true;
276 
277   for (unsigned Operand = 0; Operand < 2; ++Operand) {
278     unsigned Size = Desc.Op[Operand];
279     unsigned Signed = Size & Operation::SignBit;
280 
281     if (Size == Operation::SizeNA)
282       break;
283 
284     if (Size == Operation::BaseTypeRef && U) {
285       // For DW_OP_convert the operand may be 0 to indicate that conversion to
286       // the generic type should be done. The same holds for DW_OP_reinterpret,
287       // which is currently not supported.
288       if (Opcode == DW_OP_convert && Operands[Operand] == 0)
289         OS << " 0x0";
290       else
291         prettyPrintBaseTypeRef(U, OS, Operands, Operand);
292     } else if (Size == Operation::WasmLocationArg) {
293       assert(Operand == 1);
294       switch (Operands[0]) {
295       case 0: case 1: case 2:
296       case 3: // global as uint32
297         OS << format(" 0x%" PRIx64, Operands[Operand]);
298         break;
299       default: assert(false);
300       }
301     } else if (Size == Operation::SizeBlock) {
302       uint64_t Offset = Operands[Operand];
303       for (unsigned i = 0; i < Operands[Operand - 1]; ++i)
304         OS << format(" 0x%02x", Expr->Data.getU8(&Offset));
305     } else {
306       if (Signed)
307         OS << format(" %+" PRId64, (int64_t)Operands[Operand]);
308       else if (Opcode != DW_OP_entry_value &&
309                Opcode != DW_OP_GNU_entry_value)
310         OS << format(" 0x%" PRIx64, Operands[Operand]);
311     }
312   }
313   return true;
314 }
315 
316 void DWARFExpression::print(raw_ostream &OS, const MCRegisterInfo *RegInfo,
317                             DWARFUnit *U, bool IsEH) const {
318   uint32_t EntryValExprSize = 0;
319   for (auto &Op : *this) {
320     if (!Op.print(OS, this, RegInfo, U, IsEH)) {
321       uint64_t FailOffset = Op.getEndOffset();
322       while (FailOffset < Data.getData().size())
323         OS << format(" %02x", Data.getU8(&FailOffset));
324       return;
325     }
326 
327     if (Op.getCode() == DW_OP_entry_value ||
328         Op.getCode() == DW_OP_GNU_entry_value) {
329       OS << "(";
330       EntryValExprSize = Op.getRawOperand(0);
331       continue;
332     }
333 
334     if (EntryValExprSize) {
335       EntryValExprSize--;
336       if (EntryValExprSize == 0)
337         OS << ")";
338     }
339 
340     if (Op.getEndOffset() < Data.getData().size())
341       OS << ", ";
342   }
343 }
344 
345 bool DWARFExpression::Operation::verify(DWARFUnit *U) {
346 
347   for (unsigned Operand = 0; Operand < 2; ++Operand) {
348     unsigned Size = Desc.Op[Operand];
349 
350     if (Size == Operation::SizeNA)
351       break;
352 
353     if (Size == Operation::BaseTypeRef) {
354       // For DW_OP_convert the operand may be 0 to indicate that conversion to
355       // the generic type should be done, so don't look up a base type in that
356       // case. The same holds for DW_OP_reinterpret, which is currently not
357       // supported.
358       if (Opcode == DW_OP_convert && Operands[Operand] == 0)
359         continue;
360       auto Die = U->getDIEForOffset(U->getOffset() + Operands[Operand]);
361       if (!Die || Die.getTag() != dwarf::DW_TAG_base_type) {
362         Error = true;
363         return false;
364       }
365     }
366   }
367 
368   return true;
369 }
370 
371 bool DWARFExpression::verify(DWARFUnit *U) {
372   for (auto &Op : *this)
373     if (!Op.verify(U))
374       return false;
375 
376   return true;
377 }
378 
379 } // namespace llvm
380