LLVM  10.0.0svn
MCFixup.h
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1 //===-- llvm/MC/MCFixup.h - Instruction Relocation and Patching -*- 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_MC_MCFIXUP_H
10 #define LLVM_MC_MCFIXUP_H
11 
12 #include "llvm/MC/MCExpr.h"
13 #include "llvm/Support/DataTypes.h"
15 #include "llvm/Support/SMLoc.h"
16 #include <cassert>
17 
18 namespace llvm {
19 class MCExpr;
20 
21 /// Extensible enumeration to represent the type of a fixup.
23  FK_NONE = 0, ///< A no-op fixup.
24  FK_Data_1, ///< A one-byte fixup.
25  FK_Data_2, ///< A two-byte fixup.
26  FK_Data_4, ///< A four-byte fixup.
27  FK_Data_8, ///< A eight-byte fixup.
28  FK_Data_6b, ///< A six-bits fixup.
29  FK_PCRel_1, ///< A one-byte pc relative fixup.
30  FK_PCRel_2, ///< A two-byte pc relative fixup.
31  FK_PCRel_4, ///< A four-byte pc relative fixup.
32  FK_PCRel_8, ///< A eight-byte pc relative fixup.
33  FK_GPRel_1, ///< A one-byte gp relative fixup.
34  FK_GPRel_2, ///< A two-byte gp relative fixup.
35  FK_GPRel_4, ///< A four-byte gp relative fixup.
36  FK_GPRel_8, ///< A eight-byte gp relative fixup.
37  FK_DTPRel_4, ///< A four-byte dtp relative fixup.
38  FK_DTPRel_8, ///< A eight-byte dtp relative fixup.
39  FK_TPRel_4, ///< A four-byte tp relative fixup.
40  FK_TPRel_8, ///< A eight-byte tp relative fixup.
41  FK_SecRel_1, ///< A one-byte section relative fixup.
42  FK_SecRel_2, ///< A two-byte section relative fixup.
43  FK_SecRel_4, ///< A four-byte section relative fixup.
44  FK_SecRel_8, ///< A eight-byte section relative fixup.
45  FK_Data_Add_1, ///< A one-byte add fixup.
46  FK_Data_Add_2, ///< A two-byte add fixup.
47  FK_Data_Add_4, ///< A four-byte add fixup.
48  FK_Data_Add_8, ///< A eight-byte add fixup.
49  FK_Data_Add_6b, ///< A six-bits add fixup.
50  FK_Data_Sub_1, ///< A one-byte sub fixup.
51  FK_Data_Sub_2, ///< A two-byte sub fixup.
52  FK_Data_Sub_4, ///< A four-byte sub fixup.
53  FK_Data_Sub_8, ///< A eight-byte sub fixup.
54  FK_Data_Sub_6b, ///< A six-bits sub fixup.
55 
57 
58  // Limit range of target fixups, in case we want to pack more efficiently
59  // later.
60  MaxTargetFixupKind = (1 << 8)
61 };
62 
63 /// Encode information on a single operation to perform on a byte
64 /// sequence (e.g., an encoded instruction) which requires assemble- or run-
65 /// time patching.
66 ///
67 /// Fixups are used any time the target instruction encoder needs to represent
68 /// some value in an instruction which is not yet concrete. The encoder will
69 /// encode the instruction assuming the value is 0, and emit a fixup which
70 /// communicates to the assembler backend how it should rewrite the encoded
71 /// value.
72 ///
73 /// During the process of relaxation, the assembler will apply fixups as
74 /// symbolic values become concrete. When relaxation is complete, any remaining
75 /// fixups become relocations in the object file (or errors, if the fixup cannot
76 /// be encoded on the target).
77 class MCFixup {
78  /// The value to put into the fixup location. The exact interpretation of the
79  /// expression is target dependent, usually it will be one of the operands to
80  /// an instruction or an assembler directive.
81  const MCExpr *Value;
82 
83  /// The byte index of start of the relocation inside the MCFragment.
84  uint32_t Offset;
85 
86  /// The target dependent kind of fixup item this is. The kind is used to
87  /// determine how the operand value should be encoded into the instruction.
88  unsigned Kind;
89 
90  /// The source location which gave rise to the fixup, if any.
91  SMLoc Loc;
92 public:
93  static MCFixup create(uint32_t Offset, const MCExpr *Value,
94  MCFixupKind Kind, SMLoc Loc = SMLoc()) {
95  assert(unsigned(Kind) < MaxTargetFixupKind && "Kind out of range!");
96  MCFixup FI;
97  FI.Value = Value;
98  FI.Offset = Offset;
99  FI.Kind = unsigned(Kind);
100  FI.Loc = Loc;
101  return FI;
102  }
103 
104  /// Return a fixup corresponding to the add half of a add/sub fixup pair for
105  /// the given Fixup.
106  static MCFixup createAddFor(const MCFixup &Fixup) {
107  MCFixup FI;
108  FI.Value = Fixup.getValue();
109  FI.Offset = Fixup.getOffset();
110  FI.Kind = (unsigned)getAddKindForKind(Fixup.getKind());
111  FI.Loc = Fixup.getLoc();
112  return FI;
113  }
114 
115  /// Return a fixup corresponding to the sub half of a add/sub fixup pair for
116  /// the given Fixup.
117  static MCFixup createSubFor(const MCFixup &Fixup) {
118  MCFixup FI;
119  FI.Value = Fixup.getValue();
120  FI.Offset = Fixup.getOffset();
121  FI.Kind = (unsigned)getSubKindForKind(Fixup.getKind());
122  FI.Loc = Fixup.getLoc();
123  return FI;
124  }
125 
126  MCFixupKind getKind() const { return MCFixupKind(Kind); }
127 
128  uint32_t getOffset() const { return Offset; }
129  void setOffset(uint32_t Value) { Offset = Value; }
130 
131  const MCExpr *getValue() const { return Value; }
132 
133  /// Return the generic fixup kind for a value with the given size. It
134  /// is an error to pass an unsupported size.
135  static MCFixupKind getKindForSize(unsigned Size, bool IsPCRel) {
136  switch (Size) {
137  default: llvm_unreachable("Invalid generic fixup size!");
138  case 1:
139  return IsPCRel ? FK_PCRel_1 : FK_Data_1;
140  case 2:
141  return IsPCRel ? FK_PCRel_2 : FK_Data_2;
142  case 4:
143  return IsPCRel ? FK_PCRel_4 : FK_Data_4;
144  case 8:
145  return IsPCRel ? FK_PCRel_8 : FK_Data_8;
146  }
147  }
148 
149  /// Return the generic fixup kind for a value with the given size in bits.
150  /// It is an error to pass an unsupported size.
151  static MCFixupKind getKindForSizeInBits(unsigned Size, bool IsPCRel) {
152  switch (Size) {
153  default:
154  llvm_unreachable("Invalid generic fixup size!");
155  case 6:
156  assert(!IsPCRel && "Invalid pc-relative fixup size!");
157  return FK_Data_6b;
158  case 8:
159  return IsPCRel ? FK_PCRel_1 : FK_Data_1;
160  case 16:
161  return IsPCRel ? FK_PCRel_2 : FK_Data_2;
162  case 32:
163  return IsPCRel ? FK_PCRel_4 : FK_Data_4;
164  case 64:
165  return IsPCRel ? FK_PCRel_8 : FK_Data_8;
166  }
167  }
168 
169  /// Return the generic fixup kind for an addition with a given size. It
170  /// is an error to pass an unsupported size.
171  static MCFixupKind getAddKindForKind(unsigned Kind) {
172  switch (Kind) {
173  default: llvm_unreachable("Unknown type to convert!");
174  case FK_Data_1: return FK_Data_Add_1;
175  case FK_Data_2: return FK_Data_Add_2;
176  case FK_Data_4: return FK_Data_Add_4;
177  case FK_Data_8: return FK_Data_Add_8;
178  case FK_Data_6b: return FK_Data_Add_6b;
179  }
180  }
181 
182  /// Return the generic fixup kind for an subtraction with a given size. It
183  /// is an error to pass an unsupported size.
184  static MCFixupKind getSubKindForKind(unsigned Kind) {
185  switch (Kind) {
186  default: llvm_unreachable("Unknown type to convert!");
187  case FK_Data_1: return FK_Data_Sub_1;
188  case FK_Data_2: return FK_Data_Sub_2;
189  case FK_Data_4: return FK_Data_Sub_4;
190  case FK_Data_8: return FK_Data_Sub_8;
191  case FK_Data_6b: return FK_Data_Sub_6b;
192  }
193  }
194 
195  SMLoc getLoc() const { return Loc; }
196 };
197 
198 } // End llvm namespace
199 
200 #endif
A eight-byte pc relative fixup.
Definition: MCFixup.h:32
A eight-byte dtp relative fixup.
Definition: MCFixup.h:38
This class represents lattice values for constants.
Definition: AllocatorList.h:23
A eight-byte sub fixup.
Definition: MCFixup.h:53
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:77
A one-byte pc relative fixup.
Definition: MCFixup.h:29
A eight-byte add fixup.
Definition: MCFixup.h:48
A four-byte tp relative fixup.
Definition: MCFixup.h:39
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
A six-bits fixup.
Definition: MCFixup.h:28
static MCFixup createSubFor(const MCFixup &Fixup)
Return a fixup corresponding to the sub half of a add/sub fixup pair for the given Fixup...
Definition: MCFixup.h:117
A four-byte section relative fixup.
Definition: MCFixup.h:43
A four-byte fixup.
Definition: MCFixup.h:26
A four-byte gp relative fixup.
Definition: MCFixup.h:35
A two-byte section relative fixup.
Definition: MCFixup.h:42
A one-byte add fixup.
Definition: MCFixup.h:45
A four-byte dtp relative fixup.
Definition: MCFixup.h:37
void setOffset(uint32_t Value)
Definition: MCFixup.h:129
MCFixupKind
Extensible enumeration to represent the type of a fixup.
Definition: MCFixup.h:22
uint32_t getOffset() const
Definition: MCFixup.h:128
A eight-byte tp relative fixup.
Definition: MCFixup.h:40
static MCFixup create(uint32_t Offset, const MCExpr *Value, MCFixupKind Kind, SMLoc Loc=SMLoc())
Definition: MCFixup.h:93
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
A one-byte fixup.
Definition: MCFixup.h:24
SMLoc getLoc() const
Definition: MCFixup.h:195
A two-byte pc relative fixup.
Definition: MCFixup.h:30
A four-byte pc relative fixup.
Definition: MCFixup.h:31
A two-byte gp relative fixup.
Definition: MCFixup.h:34
A no-op fixup.
Definition: MCFixup.h:23
A four-byte add fixup.
Definition: MCFixup.h:47
A one-byte section relative fixup.
Definition: MCFixup.h:41
A six-bits sub fixup.
Definition: MCFixup.h:54
A eight-byte gp relative fixup.
Definition: MCFixup.h:36
A two-byte sub fixup.
Definition: MCFixup.h:51
A eight-byte section relative fixup.
Definition: MCFixup.h:44
static MCFixup createAddFor(const MCFixup &Fixup)
Return a fixup corresponding to the add half of a add/sub fixup pair for the given Fixup...
Definition: MCFixup.h:106
static MCFixupKind getKindForSizeInBits(unsigned Size, bool IsPCRel)
Return the generic fixup kind for a value with the given size in bits.
Definition: MCFixup.h:151
A eight-byte fixup.
Definition: MCFixup.h:27
uint32_t Size
Definition: Profile.cpp:46
A one-byte sub fixup.
Definition: MCFixup.h:50
A four-byte sub fixup.
Definition: MCFixup.h:52
static MCFixupKind getKindForSize(unsigned Size, bool IsPCRel)
Return the generic fixup kind for a value with the given size.
Definition: MCFixup.h:135
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
A one-byte gp relative fixup.
Definition: MCFixup.h:33
LLVM Value Representation.
Definition: Value.h:72
A six-bits add fixup.
Definition: MCFixup.h:49
A two-byte add fixup.
Definition: MCFixup.h:46
const MCExpr * getValue() const
Definition: MCFixup.h:131
Represents a location in source code.
Definition: SMLoc.h:23
A two-byte fixup.
Definition: MCFixup.h:25
static MCFixupKind getSubKindForKind(unsigned Kind)
Return the generic fixup kind for an subtraction with a given size.
Definition: MCFixup.h:184
MCFixupKind getKind() const
Definition: MCFixup.h:126
static MCFixupKind getAddKindForKind(unsigned Kind)
Return the generic fixup kind for an addition with a given size.
Definition: MCFixup.h:171