include/llvm/DebugInfo/DWARF/DWARFExpression.h

   1 //===--- DWARFExpression.h - DWARF Expression handling ----------*- C++ -*-===//
   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 #ifndef LLVM_DEBUGINFO_DWARFEXPRESSION_H
  10 #define LLVM_DEBUGINFO_DWARFEXPRESSION_H
  11
  12 #include "llvm/ADT/ArrayRef.h"
  13 #include "llvm/ADT/iterator.h"
  14 #include "llvm/ADT/iterator_range.h"
  15 #include "llvm/Support/DataExtractor.h"
  16
  17 namespace llvm {
  18 class DWARFUnit;
  19 class MCRegisterInfo;
  20 class raw_ostream;
  21
  22 class DWARFExpression {
  23 public:
  24   class iterator;
  25
  26   /// This class represents an Operation in the Expression. Each operation can
  27   /// have up to 2 oprerands.
  28   ///
  29   /// An Operation can be in Error state (check with isError()). This
  30   /// means that it couldn't be decoded successfully and if it is the
  31   /// case, all others fields contain undefined values.
  32   class Operation {
  33   public:
  34     /// Size and signedness of expression operations' operands.
  35     enum Encoding : uint8_t {
  36       Size1 = 0,
  37       Size2 = 1,
  38       Size4 = 2,
  39       Size8 = 3,
  40       SizeLEB = 4,
  41       SizeAddr = 5,
  42       SizeRefAddr = 6,
  43       SizeBlock = 7, ///< Preceding operand contains block size
  44       SignBit = 0x8,
  45       SignedSize1 = SignBit | Size1,
  46       SignedSize2 = SignBit | Size2,
  47       SignedSize4 = SignBit | Size4,
  48       SignedSize8 = SignBit | Size8,
  49       SignedSizeLEB = SignBit | SizeLEB,
  50       SizeNA = 0xFF ///< Unused operands get this encoding.
  51     };
  52
  53     enum DwarfVersion : uint8_t {
  54       DwarfNA, ///< Serves as a marker for unused entries
  55       Dwarf2 = 2,
  56       Dwarf3,
  57       Dwarf4
  58     };
  59
  60     /// Description of the encoding of one expression Op.
  61     struct Description {
  62       DwarfVersion Version; ///< Dwarf version where the Op was introduced.
  63       Encoding Op[2];       ///< Encoding for Op operands, or SizeNA.
  64
  65       Description(DwarfVersion Version = DwarfNA, Encoding Op1 = SizeNA,
  66                   Encoding Op2 = SizeNA)
  67           : Version(Version) {
  68         Op[0] = Op1;
  69         Op[1] = Op2;
  70       }
  71     };
  72
  73   private:
  74     friend class DWARFExpression::iterator;
  75     uint8_t Opcode; ///< The Op Opcode, DW_OP_<something>.
  76     Description Desc;
  77     bool Error;
  78     uint32_t EndOffset;
  79     uint64_t Operands[2];
  80
  81   public:
  82     Description &getDescription() { return Desc; }
  83     uint8_t getCode() { return Opcode; }
  84     uint64_t getRawOperand(unsigned Idx) { return Operands[Idx]; }
  85     uint32_t getEndOffset() { return EndOffset; }
  86     bool extract(DataExtractor Data, uint16_t Version, uint8_t AddressSize,
  87                  uint32_t Offset);
  88     bool isError() { return Error; }
  89     bool print(raw_ostream &OS, const DWARFExpression *U,
  90                const MCRegisterInfo *RegInfo, bool isEH);
  91   };
  92
  93   /// An iterator to go through the expression operations.
  94   class iterator
  95       : public iterator_facade_base<iterator, std::forward_iterator_tag,
  96                                     Operation> {
  97     friend class DWARFExpression;
  98     const DWARFExpression *Expr;
  99     uint32_t Offset;
 100     Operation Op;
 101     iterator(const DWARFExpression *Expr, uint32_t Offset)
 102         : Expr(Expr), Offset(Offset) {
 103       Op.Error =
 104           Offset >= Expr->Data.getData().size() ||
 105           !Op.extract(Expr->Data, Expr->Version, Expr->AddressSize, Offset);
 106     }
 107
 108   public:
 109     class Operation &operator++() {
 110       Offset = Op.isError() ? Expr->Data.getData().size() : Op.EndOffset;
 111       Op.Error =
 112           Offset >= Expr->Data.getData().size() ||
 113           !Op.extract(Expr->Data, Expr->Version, Expr->AddressSize, Offset);
 114       return Op;
 115     }
 116
 117     class Operation &operator*() {
 118       return Op;
 119     }
 120
 121     // Comparison operators are provided out of line.
 122     friend bool operator==(const iterator &, const iterator &);
 123   };
 124
 125   DWARFExpression(DataExtractor Data, uint16_t Version, uint8_t AddressSize)
 126       : Data(Data), Version(Version), AddressSize(AddressSize) {
 127     assert(AddressSize == 8 || AddressSize == 4);
 128   }
 129
 130   iterator begin() const { return iterator(this, 0); }
 131   iterator end() const { return iterator(this, Data.getData().size()); }
 132
 133   void print(raw_ostream &OS, const MCRegisterInfo *RegInfo,
 134              bool IsEH = false) const;
 135
 136 private:
 137   DataExtractor Data;
 138   uint16_t Version;
 139   uint8_t AddressSize;
 140 };
 141
 142 inline bool operator==(const DWARFExpression::iterator &LHS,
 143                        const DWARFExpression::iterator &RHS) {
 144   return LHS.Expr == RHS.Expr && LHS.Offset == RHS.Offset;
 145 }
 146
 147 inline bool operator!=(const DWARFExpression::iterator &LHS,
 148                        const DWARFExpression::iterator &RHS) {
 149   return !(LHS == RHS);
 150 }
 151 }
 152 #endif