1 //===-- DWARFExpression.cpp -----------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/DebugInfo/DWARF/DWARFExpression.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 
getDescriptions()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   return Descriptions;
101 }
102 
getOpDesc(unsigned OpCode)103 static DWARFExpression::Operation::Description getOpDesc(unsigned OpCode) {
104   // FIXME: Make this constexpr once all compilers are smart enough to do it.
105   static DescVector Descriptions = getDescriptions();
106   // Handle possible corrupted or unsupported operation.
107   if (OpCode >= Descriptions.size())
108     return {};
109   return Descriptions[OpCode];
110 }
111 
getRefAddrSize(uint8_t AddrSize,uint16_t Version)112 static uint8_t getRefAddrSize(uint8_t AddrSize, uint16_t Version) {
113   return (Version == 2) ? AddrSize : 4;
114 }
115 
extract(DataExtractor Data,uint16_t Version,uint8_t AddressSize,uint32_t Offset)116 bool DWARFExpression::Operation::extract(DataExtractor Data, uint16_t Version,
117                                          uint8_t AddressSize, uint32_t Offset) {
118   Opcode = Data.getU8(&Offset);
119 
120   Desc = getOpDesc(Opcode);
121   if (Desc.Version == Operation::DwarfNA) {
122     EndOffset = Offset;
123     return false;
124   }
125 
126   for (unsigned Operand = 0; Operand < 2; ++Operand) {
127     unsigned Size = Desc.Op[Operand];
128     unsigned Signed = Size & Operation::SignBit;
129 
130     if (Size == Operation::SizeNA)
131       break;
132 
133     switch (Size & ~Operation::SignBit) {
134     case Operation::Size1:
135       Operands[Operand] = Data.getU8(&Offset);
136       if (Signed)
137         Operands[Operand] = (int8_t)Operands[Operand];
138       break;
139     case Operation::Size2:
140       Operands[Operand] = Data.getU16(&Offset);
141       if (Signed)
142         Operands[Operand] = (int16_t)Operands[Operand];
143       break;
144     case Operation::Size4:
145       Operands[Operand] = Data.getU32(&Offset);
146       if (Signed)
147         Operands[Operand] = (int32_t)Operands[Operand];
148       break;
149     case Operation::Size8:
150       Operands[Operand] = Data.getU64(&Offset);
151       break;
152     case Operation::SizeAddr:
153       if (AddressSize == 8) {
154         Operands[Operand] = Data.getU64(&Offset);
155       } else {
156         assert(AddressSize == 4);
157         Operands[Operand] = Data.getU32(&Offset);
158       }
159       break;
160     case Operation::SizeRefAddr:
161       if (getRefAddrSize(AddressSize, Version) == 8) {
162         Operands[Operand] = Data.getU64(&Offset);
163       } else {
164         assert(getRefAddrSize(AddressSize, Version) == 4);
165         Operands[Operand] = Data.getU32(&Offset);
166       }
167       break;
168     case Operation::SizeLEB:
169       if (Signed)
170         Operands[Operand] = Data.getSLEB128(&Offset);
171       else
172         Operands[Operand] = Data.getULEB128(&Offset);
173       break;
174     case Operation::SizeBlock:
175       // We need a size, so this cannot be the first operand
176       if (Operand == 0)
177         return false;
178       // Store the offset of the block as the value.
179       Operands[Operand] = Offset;
180       Offset += Operands[Operand - 1];
181       break;
182     default:
183       llvm_unreachable("Unknown DWARFExpression Op size");
184     }
185   }
186 
187   EndOffset = Offset;
188   return true;
189 }
190 
prettyPrintRegisterOp(raw_ostream & OS,uint8_t Opcode,uint64_t Operands[2],const MCRegisterInfo * MRI,bool isEH)191 static bool prettyPrintRegisterOp(raw_ostream &OS, uint8_t Opcode,
192                                   uint64_t Operands[2],
193                                   const MCRegisterInfo *MRI, bool isEH) {
194   if (!MRI)
195     return false;
196 
197   uint64_t DwarfRegNum;
198   unsigned OpNum = 0;
199 
200   if (Opcode == DW_OP_bregx || Opcode == DW_OP_regx)
201     DwarfRegNum = Operands[OpNum++];
202   else if (Opcode >= DW_OP_breg0 && Opcode < DW_OP_bregx)
203     DwarfRegNum = Opcode - DW_OP_breg0;
204   else
205     DwarfRegNum = Opcode - DW_OP_reg0;
206 
207   int LLVMRegNum = MRI->getLLVMRegNum(DwarfRegNum, isEH);
208   if (LLVMRegNum >= 0) {
209     if (const char *RegName = MRI->getName(LLVMRegNum)) {
210       if ((Opcode >= DW_OP_breg0 && Opcode <= DW_OP_breg31) ||
211           Opcode == DW_OP_bregx)
212         OS << format(" %s%+" PRId64, RegName, Operands[OpNum]);
213       else
214         OS << ' ' << RegName;
215       return true;
216     }
217   }
218 
219   return false;
220 }
221 
print(raw_ostream & OS,const DWARFExpression * Expr,const MCRegisterInfo * RegInfo,bool isEH)222 bool DWARFExpression::Operation::print(raw_ostream &OS,
223                                        const DWARFExpression *Expr,
224                                        const MCRegisterInfo *RegInfo,
225                                        bool isEH) {
226   if (Error) {
227     OS << "<decoding error>";
228     return false;
229   }
230 
231   StringRef Name = OperationEncodingString(Opcode);
232   assert(!Name.empty() && "DW_OP has no name!");
233   OS << Name;
234 
235   if ((Opcode >= DW_OP_breg0 && Opcode <= DW_OP_breg31) ||
236       (Opcode >= DW_OP_reg0 && Opcode <= DW_OP_reg31) ||
237       Opcode == DW_OP_bregx || Opcode == DW_OP_regx)
238     if (prettyPrintRegisterOp(OS, Opcode, Operands, RegInfo, isEH))
239       return true;
240 
241   for (unsigned Operand = 0; Operand < 2; ++Operand) {
242     unsigned Size = Desc.Op[Operand];
243     unsigned Signed = Size & Operation::SignBit;
244 
245     if (Size == Operation::SizeNA)
246       break;
247 
248     if (Size == Operation::SizeBlock) {
249       uint32_t Offset = Operands[Operand];
250       for (unsigned i = 0; i < Operands[Operand - 1]; ++i)
251         OS << format(" 0x%02x", Expr->Data.getU8(&Offset));
252     } else {
253       if (Signed)
254         OS << format(" %+" PRId64, (int64_t)Operands[Operand]);
255       else
256         OS << format(" 0x%" PRIx64, Operands[Operand]);
257     }
258   }
259   return true;
260 }
261 
print(raw_ostream & OS,const MCRegisterInfo * RegInfo,bool IsEH) const262 void DWARFExpression::print(raw_ostream &OS, const MCRegisterInfo *RegInfo,
263                             bool IsEH) const {
264   for (auto &Op : *this) {
265     if (!Op.print(OS, this, RegInfo, IsEH)) {
266       uint32_t FailOffset = Op.getEndOffset();
267       while (FailOffset < Data.getData().size())
268         OS << format(" %02x", Data.getU8(&FailOffset));
269       return;
270     }
271     if (Op.getEndOffset() < Data.getData().size())
272       OS << ", ";
273   }
274 }
275 
276 } // namespace llvm
277