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/BinaryFormat/Dwarf.h"
12 #include "llvm/MC/MCRegisterInfo.h"
13 #include "llvm/Support/Format.h"
14 #include <cassert>
15 #include <cstdint>
16 #include <vector>
17 
18 using namespace llvm;
19 using namespace dwarf;
20 
21 namespace llvm {
22 
23 typedef std::vector<DWARFExpression::Operation::Description> DescVector;
24 
25 static DescVector getDescriptions() {
26   DescVector Descriptions;
27   typedef DWARFExpression::Operation Op;
28   typedef Op::Description Desc;
29 
30   Descriptions.resize(0xff);
31   Descriptions[DW_OP_addr] = Desc(Op::Dwarf2, Op::SizeAddr);
32   Descriptions[DW_OP_deref] = Desc(Op::Dwarf2);
33   Descriptions[DW_OP_const1u] = Desc(Op::Dwarf2, Op::Size1);
34   Descriptions[DW_OP_const1s] = Desc(Op::Dwarf2, Op::SignedSize1);
35   Descriptions[DW_OP_const2u] = Desc(Op::Dwarf2, Op::Size2);
36   Descriptions[DW_OP_const2s] = Desc(Op::Dwarf2, Op::SignedSize2);
37   Descriptions[DW_OP_const4u] = Desc(Op::Dwarf2, Op::Size4);
38   Descriptions[DW_OP_const4s] = Desc(Op::Dwarf2, Op::SignedSize4);
39   Descriptions[DW_OP_const8u] = Desc(Op::Dwarf2, Op::Size8);
40   Descriptions[DW_OP_const8s] = Desc(Op::Dwarf2, Op::SignedSize8);
41   Descriptions[DW_OP_constu] = Desc(Op::Dwarf2, Op::SizeLEB);
42   Descriptions[DW_OP_consts] = Desc(Op::Dwarf2, Op::SignedSizeLEB);
43   Descriptions[DW_OP_dup] = Desc(Op::Dwarf2);
44   Descriptions[DW_OP_drop] = Desc(Op::Dwarf2);
45   Descriptions[DW_OP_over] = Desc(Op::Dwarf2);
46   Descriptions[DW_OP_pick] = Desc(Op::Dwarf2, Op::Size1);
47   Descriptions[DW_OP_swap] = Desc(Op::Dwarf2);
48   Descriptions[DW_OP_rot] = Desc(Op::Dwarf2);
49   Descriptions[DW_OP_xderef] = Desc(Op::Dwarf2);
50   Descriptions[DW_OP_abs] = Desc(Op::Dwarf2);
51   Descriptions[DW_OP_and] = Desc(Op::Dwarf2);
52   Descriptions[DW_OP_div] = Desc(Op::Dwarf2);
53   Descriptions[DW_OP_minus] = Desc(Op::Dwarf2);
54   Descriptions[DW_OP_mod] = Desc(Op::Dwarf2);
55   Descriptions[DW_OP_mul] = Desc(Op::Dwarf2);
56   Descriptions[DW_OP_neg] = Desc(Op::Dwarf2);
57   Descriptions[DW_OP_not] = Desc(Op::Dwarf2);
58   Descriptions[DW_OP_or] = Desc(Op::Dwarf2);
59   Descriptions[DW_OP_plus] = Desc(Op::Dwarf2);
60   Descriptions[DW_OP_plus_uconst] = Desc(Op::Dwarf2, Op::SizeLEB);
61   Descriptions[DW_OP_shl] = Desc(Op::Dwarf2);
62   Descriptions[DW_OP_shr] = Desc(Op::Dwarf2);
63   Descriptions[DW_OP_shra] = Desc(Op::Dwarf2);
64   Descriptions[DW_OP_xor] = Desc(Op::Dwarf2);
65   Descriptions[DW_OP_skip] = Desc(Op::Dwarf2, Op::SignedSize2);
66   Descriptions[DW_OP_bra] = Desc(Op::Dwarf2, Op::SignedSize2);
67   Descriptions[DW_OP_eq] = Desc(Op::Dwarf2);
68   Descriptions[DW_OP_ge] = Desc(Op::Dwarf2);
69   Descriptions[DW_OP_gt] = Desc(Op::Dwarf2);
70   Descriptions[DW_OP_le] = Desc(Op::Dwarf2);
71   Descriptions[DW_OP_lt] = Desc(Op::Dwarf2);
72   Descriptions[DW_OP_ne] = Desc(Op::Dwarf2);
73   for (uint16_t LA = DW_OP_lit0; LA <= DW_OP_lit31; ++LA)
74     Descriptions[LA] = Desc(Op::Dwarf2);
75   for (uint16_t LA = DW_OP_reg0; LA <= DW_OP_reg31; ++LA)
76     Descriptions[LA] = Desc(Op::Dwarf2);
77   for (uint16_t LA = DW_OP_breg0; LA <= DW_OP_breg31; ++LA)
78     Descriptions[LA] = Desc(Op::Dwarf2, Op::SignedSizeLEB);
79   Descriptions[DW_OP_regx] = Desc(Op::Dwarf2, Op::SizeLEB);
80   Descriptions[DW_OP_fbreg] = Desc(Op::Dwarf2, Op::SignedSizeLEB);
81   Descriptions[DW_OP_bregx] = Desc(Op::Dwarf2, Op::SizeLEB, Op::SignedSizeLEB);
82   Descriptions[DW_OP_piece] = Desc(Op::Dwarf2, Op::SizeLEB);
83   Descriptions[DW_OP_deref_size] = Desc(Op::Dwarf2, Op::Size1);
84   Descriptions[DW_OP_xderef_size] = Desc(Op::Dwarf2, Op::Size1);
85   Descriptions[DW_OP_nop] = Desc(Op::Dwarf2);
86   Descriptions[DW_OP_push_object_address] = Desc(Op::Dwarf3);
87   Descriptions[DW_OP_call2] = Desc(Op::Dwarf3, Op::Size2);
88   Descriptions[DW_OP_call4] = Desc(Op::Dwarf3, Op::Size4);
89   Descriptions[DW_OP_call_ref] = Desc(Op::Dwarf3, Op::SizeRefAddr);
90   Descriptions[DW_OP_form_tls_address] = Desc(Op::Dwarf3);
91   Descriptions[DW_OP_call_frame_cfa] = Desc(Op::Dwarf3);
92   Descriptions[DW_OP_bit_piece] = Desc(Op::Dwarf3, Op::SizeLEB, Op::SizeLEB);
93   Descriptions[DW_OP_implicit_value] =
94       Desc(Op::Dwarf3, Op::SizeLEB, Op::SizeBlock);
95   Descriptions[DW_OP_stack_value] = Desc(Op::Dwarf3);
96   Descriptions[DW_OP_GNU_push_tls_address] = Desc(Op::Dwarf3);
97   Descriptions[DW_OP_addrx] = Desc(Op::Dwarf4, Op::SizeLEB);
98   Descriptions[DW_OP_GNU_addr_index] = Desc(Op::Dwarf4, Op::SizeLEB);
99   Descriptions[DW_OP_GNU_const_index] = Desc(Op::Dwarf4, Op::SizeLEB);
100 
101   Descriptions[DW_OP_convert] = Desc(Op::Dwarf5, Op::BaseTypeRef);
102 
103   return Descriptions;
104 }
105 
106 static DWARFExpression::Operation::Description getOpDesc(unsigned OpCode) {
107   // FIXME: Make this constexpr once all compilers are smart enough to do it.
108   static DescVector Descriptions = getDescriptions();
109   // Handle possible corrupted or unsupported operation.
110   if (OpCode >= Descriptions.size())
111     return {};
112   return Descriptions[OpCode];
113 }
114 
115 static uint8_t getRefAddrSize(uint8_t AddrSize, uint16_t Version) {
116   return (Version == 2) ? AddrSize : 4;
117 }
118 
119 bool DWARFExpression::Operation::extract(DataExtractor Data, uint16_t Version,
120                                          uint8_t AddressSize, uint32_t Offset) {
121   Opcode = Data.getU8(&Offset);
122 
123   Desc = getOpDesc(Opcode);
124   if (Desc.Version == Operation::DwarfNA) {
125     EndOffset = Offset;
126     return false;
127   }
128 
129   for (unsigned Operand = 0; Operand < 2; ++Operand) {
130     unsigned Size = Desc.Op[Operand];
131     unsigned Signed = Size & Operation::SignBit;
132 
133     if (Size == Operation::SizeNA)
134       break;
135 
136     switch (Size & ~Operation::SignBit) {
137     case Operation::Size1:
138       Operands[Operand] = Data.getU8(&Offset);
139       if (Signed)
140         Operands[Operand] = (int8_t)Operands[Operand];
141       break;
142     case Operation::Size2:
143       Operands[Operand] = Data.getU16(&Offset);
144       if (Signed)
145         Operands[Operand] = (int16_t)Operands[Operand];
146       break;
147     case Operation::Size4:
148       Operands[Operand] = Data.getU32(&Offset);
149       if (Signed)
150         Operands[Operand] = (int32_t)Operands[Operand];
151       break;
152     case Operation::Size8:
153       Operands[Operand] = Data.getU64(&Offset);
154       break;
155     case Operation::SizeAddr:
156       if (AddressSize == 8) {
157         Operands[Operand] = Data.getU64(&Offset);
158       } else if (AddressSize == 4) {
159         Operands[Operand] = Data.getU32(&Offset);
160       } else {
161         assert(AddressSize == 2);
162         Operands[Operand] = Data.getU16(&Offset);
163       }
164       break;
165     case Operation::SizeRefAddr:
166       if (getRefAddrSize(AddressSize, Version) == 8) {
167         Operands[Operand] = Data.getU64(&Offset);
168       } else if (getRefAddrSize(AddressSize, Version) == 4) {
169         Operands[Operand] = Data.getU32(&Offset);
170       } else {
171         assert(getRefAddrSize(AddressSize, Version) == 2);
172         Operands[Operand] = Data.getU16(&Offset);
173       }
174       break;
175     case Operation::SizeLEB:
176       if (Signed)
177         Operands[Operand] = Data.getSLEB128(&Offset);
178       else
179         Operands[Operand] = Data.getULEB128(&Offset);
180       break;
181     case Operation::BaseTypeRef:
182       Operands[Operand] = Data.getULEB128(&Offset);
183       break;
184     case Operation::SizeBlock:
185       // We need a size, so this cannot be the first operand
186       if (Operand == 0)
187         return false;
188       // Store the offset of the block as the value.
189       Operands[Operand] = Offset;
190       Offset += Operands[Operand - 1];
191       break;
192     default:
193       llvm_unreachable("Unknown DWARFExpression Op size");
194     }
195 
196     OperandEndOffsets[Operand] = Offset;
197   }
198 
199   EndOffset = Offset;
200   return true;
201 }
202 
203 static bool prettyPrintRegisterOp(raw_ostream &OS, uint8_t Opcode,
204                                   uint64_t Operands[2],
205                                   const MCRegisterInfo *MRI, bool isEH) {
206   if (!MRI)
207     return false;
208 
209   uint64_t DwarfRegNum;
210   unsigned OpNum = 0;
211 
212   if (Opcode == DW_OP_bregx || Opcode == DW_OP_regx)
213     DwarfRegNum = Operands[OpNum++];
214   else if (Opcode >= DW_OP_breg0 && Opcode < DW_OP_bregx)
215     DwarfRegNum = Opcode - DW_OP_breg0;
216   else
217     DwarfRegNum = Opcode - DW_OP_reg0;
218 
219   int LLVMRegNum = MRI->getLLVMRegNum(DwarfRegNum, isEH);
220   if (LLVMRegNum >= 0) {
221     if (const char *RegName = MRI->getName(LLVMRegNum)) {
222       if ((Opcode >= DW_OP_breg0 && Opcode <= DW_OP_breg31) ||
223           Opcode == DW_OP_bregx)
224         OS << format(" %s%+" PRId64, RegName, Operands[OpNum]);
225       else
226         OS << ' ' << RegName;
227       return true;
228     }
229   }
230 
231   return false;
232 }
233 
234 bool DWARFExpression::Operation::print(raw_ostream &OS,
235                                        const DWARFExpression *Expr,
236                                        const MCRegisterInfo *RegInfo,
237                                        DWARFUnit *U,
238                                        bool isEH) {
239   if (Error) {
240     OS << "<decoding error>";
241     return false;
242   }
243 
244   StringRef Name = OperationEncodingString(Opcode);
245   assert(!Name.empty() && "DW_OP has no name!");
246   OS << Name;
247 
248   if ((Opcode >= DW_OP_breg0 && Opcode <= DW_OP_breg31) ||
249       (Opcode >= DW_OP_reg0 && Opcode <= DW_OP_reg31) ||
250       Opcode == DW_OP_bregx || Opcode == DW_OP_regx)
251     if (prettyPrintRegisterOp(OS, Opcode, Operands, RegInfo, isEH))
252       return true;
253 
254   for (unsigned Operand = 0; Operand < 2; ++Operand) {
255     unsigned Size = Desc.Op[Operand];
256     unsigned Signed = Size & Operation::SignBit;
257 
258     if (Size == Operation::SizeNA)
259       break;
260 
261     if (Size == Operation::BaseTypeRef && U) {
262       auto Die = U->getDIEForOffset(U->getOffset() + Operands[Operand]);
263       if (Die && Die.getTag() == dwarf::DW_TAG_base_type) {
264         OS << format(" (0x%08x)", U->getOffset() + Operands[Operand]);
265         if (auto Name = Die.find(dwarf::DW_AT_name))
266           OS << " \"" << Name->getAsCString() << "\"";
267       } else {
268         OS << format(" <invalid base_type ref: 0x%" PRIx64 ">",
269                      Operands[Operand]);
270       }
271     } else if (Size == Operation::SizeBlock) {
272       uint32_t Offset = Operands[Operand];
273       for (unsigned i = 0; i < Operands[Operand - 1]; ++i)
274         OS << format(" 0x%02x", Expr->Data.getU8(&Offset));
275     } else {
276       if (Signed)
277         OS << format(" %+" PRId64, (int64_t)Operands[Operand]);
278       else
279         OS << format(" 0x%" PRIx64, Operands[Operand]);
280     }
281   }
282   return true;
283 }
284 
285 void DWARFExpression::print(raw_ostream &OS, const MCRegisterInfo *RegInfo,
286                             DWARFUnit *U, bool IsEH) const {
287   for (auto &Op : *this) {
288     if (!Op.print(OS, this, RegInfo, U, IsEH)) {
289       uint32_t FailOffset = Op.getEndOffset();
290       while (FailOffset < Data.getData().size())
291         OS << format(" %02x", Data.getU8(&FailOffset));
292       return;
293     }
294     if (Op.getEndOffset() < Data.getData().size())
295       OS << ", ";
296   }
297 }
298 
299 bool DWARFExpression::Operation::verify(DWARFUnit *U) {
300 
301   for (unsigned Operand = 0; Operand < 2; ++Operand) {
302     unsigned Size = Desc.Op[Operand];
303 
304     if (Size == Operation::SizeNA)
305       break;
306 
307     if (Size == Operation::BaseTypeRef) {
308       auto Die = U->getDIEForOffset(U->getOffset() + Operands[Operand]);
309       if (!Die || Die.getTag() != dwarf::DW_TAG_base_type) {
310         Error = true;
311         return false;
312       }
313     }
314   }
315 
316   return true;
317 }
318 
319 bool DWARFExpression::verify(DWARFUnit *U) {
320   for (auto &Op : *this)
321     if (!Op.verify(U))
322       return false;
323 
324   return true;
325 }
326 
327 } // namespace llvm
328