LLVM  14.0.0git
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/Support/DataTypes.h"
14 #include "llvm/Support/SMLoc.h"
15 #include <cassert>
16 
17 namespace llvm {
18 class MCExpr;
19 
20 /// Extensible enumeration to represent the type of a fixup.
22  FK_NONE = 0, ///< A no-op fixup.
23  FK_Data_1, ///< A one-byte fixup.
24  FK_Data_2, ///< A two-byte fixup.
25  FK_Data_4, ///< A four-byte fixup.
26  FK_Data_8, ///< A eight-byte fixup.
27  FK_Data_6b, ///< A six-bits fixup.
28  FK_PCRel_1, ///< A one-byte pc relative fixup.
29  FK_PCRel_2, ///< A two-byte pc relative fixup.
30  FK_PCRel_4, ///< A four-byte pc relative fixup.
31  FK_PCRel_8, ///< A eight-byte pc relative fixup.
32  FK_GPRel_1, ///< A one-byte gp relative fixup.
33  FK_GPRel_2, ///< A two-byte gp relative fixup.
34  FK_GPRel_4, ///< A four-byte gp relative fixup.
35  FK_GPRel_8, ///< A eight-byte gp relative fixup.
36  FK_DTPRel_4, ///< A four-byte dtp relative fixup.
37  FK_DTPRel_8, ///< A eight-byte dtp relative fixup.
38  FK_TPRel_4, ///< A four-byte tp relative fixup.
39  FK_TPRel_8, ///< A eight-byte tp relative fixup.
40  FK_SecRel_1, ///< A one-byte section relative fixup.
41  FK_SecRel_2, ///< A two-byte section relative fixup.
42  FK_SecRel_4, ///< A four-byte section relative fixup.
43  FK_SecRel_8, ///< A eight-byte section relative fixup.
44 
46 
47  /// The range [FirstLiteralRelocationKind, MaxTargetFixupKind) is used for
48  /// relocations coming from .reloc directive. Fixup kind
49  /// FirstLiteralRelocationKind+V represents the relocation type with number V.
51 
52  /// Set limit to accommodate the highest reloc type in use for all Targets,
53  /// currently R_AARCH64_IRELATIVE at 1032, including room for expansion.
55 };
56 
57 /// Encode information on a single operation to perform on a byte
58 /// sequence (e.g., an encoded instruction) which requires assemble- or run-
59 /// time patching.
60 ///
61 /// Fixups are used any time the target instruction encoder needs to represent
62 /// some value in an instruction which is not yet concrete. The encoder will
63 /// encode the instruction assuming the value is 0, and emit a fixup which
64 /// communicates to the assembler backend how it should rewrite the encoded
65 /// value.
66 ///
67 /// During the process of relaxation, the assembler will apply fixups as
68 /// symbolic values become concrete. When relaxation is complete, any remaining
69 /// fixups become relocations in the object file (or errors, if the fixup cannot
70 /// be encoded on the target).
71 class MCFixup {
72  /// The value to put into the fixup location. The exact interpretation of the
73  /// expression is target dependent, usually it will be one of the operands to
74  /// an instruction or an assembler directive.
75  const MCExpr *Value = nullptr;
76 
77  /// The byte index of start of the relocation inside the MCFragment.
78  uint32_t Offset = 0;
79 
80  /// The target dependent kind of fixup item this is. The kind is used to
81  /// determine how the operand value should be encoded into the instruction.
82  MCFixupKind Kind = FK_NONE;
83 
84  /// The source location which gave rise to the fixup, if any.
85  SMLoc Loc;
86 public:
87  static MCFixup create(uint32_t Offset, const MCExpr *Value,
88  MCFixupKind Kind, SMLoc Loc = SMLoc()) {
89  assert(Kind <= MaxFixupKind && "Kind out of range!");
90  MCFixup FI;
91  FI.Value = Value;
92  FI.Offset = Offset;
93  FI.Kind = Kind;
94  FI.Loc = Loc;
95  return FI;
96  }
97 
98  MCFixupKind getKind() const { return Kind; }
99 
100  unsigned getTargetKind() const { return Kind; }
101 
102  uint32_t getOffset() const { return Offset; }
103  void setOffset(uint32_t Value) { Offset = Value; }
104 
105  const MCExpr *getValue() const { return Value; }
106 
107  /// Return the generic fixup kind for a value with the given size. It
108  /// is an error to pass an unsupported size.
109  static MCFixupKind getKindForSize(unsigned Size, bool IsPCRel) {
110  switch (Size) {
111  default: llvm_unreachable("Invalid generic fixup size!");
112  case 1:
113  return IsPCRel ? FK_PCRel_1 : FK_Data_1;
114  case 2:
115  return IsPCRel ? FK_PCRel_2 : FK_Data_2;
116  case 4:
117  return IsPCRel ? FK_PCRel_4 : FK_Data_4;
118  case 8:
119  return IsPCRel ? FK_PCRel_8 : FK_Data_8;
120  }
121  }
122 
123  /// Return the generic fixup kind for a value with the given size in bits.
124  /// It is an error to pass an unsupported size.
125  static MCFixupKind getKindForSizeInBits(unsigned Size, bool IsPCRel) {
126  switch (Size) {
127  default:
128  llvm_unreachable("Invalid generic fixup size!");
129  case 6:
130  assert(!IsPCRel && "Invalid pc-relative fixup size!");
131  return FK_Data_6b;
132  case 8:
133  return IsPCRel ? FK_PCRel_1 : FK_Data_1;
134  case 16:
135  return IsPCRel ? FK_PCRel_2 : FK_Data_2;
136  case 32:
137  return IsPCRel ? FK_PCRel_4 : FK_Data_4;
138  case 64:
139  return IsPCRel ? FK_PCRel_8 : FK_Data_8;
140  }
141  }
142 
143  SMLoc getLoc() const { return Loc; }
144 };
145 
146 } // End llvm namespace
147 
148 #endif
llvm::Check::Size
@ Size
Definition: FileCheck.h:73
llvm
This file implements support for optimizing divisions by a constant.
Definition: AllocatorList.h:23
llvm::FK_PCRel_8
@ FK_PCRel_8
A eight-byte pc relative fixup.
Definition: MCFixup.h:31
llvm::MCFixup::getKindForSizeInBits
static MCFixupKind getKindForSizeInBits(unsigned Size, bool IsPCRel)
Return the generic fixup kind for a value with the given size in bits.
Definition: MCFixup.h:125
llvm::FK_DTPRel_8
@ FK_DTPRel_8
A eight-byte dtp relative fixup.
Definition: MCFixup.h:37
llvm::FirstTargetFixupKind
@ FirstTargetFixupKind
Definition: MCFixup.h:45
llvm::MCFixup::create
static MCFixup create(uint32_t Offset, const MCExpr *Value, MCFixupKind Kind, SMLoc Loc=SMLoc())
Definition: MCFixup.h:87
ErrorHandling.h
llvm::FK_PCRel_1
@ FK_PCRel_1
A one-byte pc relative fixup.
Definition: MCFixup.h:28
llvm::FK_TPRel_4
@ FK_TPRel_4
A four-byte tp relative fixup.
Definition: MCFixup.h:38
llvm::MCFixup::getLoc
SMLoc getLoc() const
Definition: MCFixup.h:143
llvm::FirstLiteralRelocationKind
@ FirstLiteralRelocationKind
The range [FirstLiteralRelocationKind, MaxTargetFixupKind) is used for relocations coming from ....
Definition: MCFixup.h:50
llvm::MCFixup::getValue
const MCExpr * getValue() const
Definition: MCFixup.h:105
llvm::FK_Data_4
@ FK_Data_4
A four-byte fixup.
Definition: MCFixup.h:25
llvm::MCFixup::getKindForSize
static MCFixupKind getKindForSize(unsigned Size, bool IsPCRel)
Return the generic fixup kind for a value with the given size.
Definition: MCFixup.h:109
llvm::FK_GPRel_4
@ FK_GPRel_4
A four-byte gp relative fixup.
Definition: MCFixup.h:34
llvm::FK_Data_6b
@ FK_Data_6b
A six-bits fixup.
Definition: MCFixup.h:27
llvm::SMLoc
Represents a location in source code.
Definition: SMLoc.h:23
llvm::FK_SecRel_4
@ FK_SecRel_4
A four-byte section relative fixup.
Definition: MCFixup.h:42
llvm::FK_SecRel_2
@ FK_SecRel_2
A two-byte section relative fixup.
Definition: MCFixup.h:41
SMLoc.h
llvm::FK_DTPRel_4
@ FK_DTPRel_4
A four-byte dtp relative fixup.
Definition: MCFixup.h:36
llvm::MaxFixupKind
@ MaxFixupKind
Set limit to accommodate the highest reloc type in use for all Targets, currently R_AARCH64_IRELATIVE...
Definition: MCFixup.h:54
llvm::FK_TPRel_8
@ FK_TPRel_8
A eight-byte tp relative fixup.
Definition: MCFixup.h:39
assert
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
llvm::FK_PCRel_2
@ FK_PCRel_2
A two-byte pc relative fixup.
Definition: MCFixup.h:29
llvm::FK_Data_1
@ FK_Data_1
A one-byte fixup.
Definition: MCFixup.h:23
llvm::FK_PCRel_4
@ FK_PCRel_4
A four-byte pc relative fixup.
Definition: MCFixup.h:30
llvm::FK_NONE
@ FK_NONE
A no-op fixup.
Definition: MCFixup.h:22
llvm::MCFixup::setOffset
void setOffset(uint32_t Value)
Definition: MCFixup.h:103
llvm_unreachable
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:134
uint32_t
llvm::FK_GPRel_2
@ FK_GPRel_2
A two-byte gp relative fixup.
Definition: MCFixup.h:33
llvm::FK_SecRel_1
@ FK_SecRel_1
A one-byte section relative fixup.
Definition: MCFixup.h:40
llvm::MCFixup::getTargetKind
unsigned getTargetKind() const
Definition: MCFixup.h:100
llvm::MCFixup::getKind
MCFixupKind getKind() const
Definition: MCFixup.h:98
llvm::FK_SecRel_8
@ FK_SecRel_8
A eight-byte section relative fixup.
Definition: MCFixup.h:43
llvm::FK_GPRel_8
@ FK_GPRel_8
A eight-byte gp relative fixup.
Definition: MCFixup.h:35
llvm::MCFixupKind
MCFixupKind
Extensible enumeration to represent the type of a fixup.
Definition: MCFixup.h:21
llvm::FK_Data_8
@ FK_Data_8
A eight-byte fixup.
Definition: MCFixup.h:26
llvm::FK_GPRel_1
@ FK_GPRel_1
A one-byte gp relative fixup.
Definition: MCFixup.h:32
DataTypes.h
llvm::FK_Data_2
@ FK_Data_2
A two-byte fixup.
Definition: MCFixup.h:24
llvm::MCFixup
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:71
llvm::Value
LLVM Value Representation.
Definition: Value.h:75
llvm::MCExpr
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
llvm::MCFixup::getOffset
uint32_t getOffset() const
Definition: MCFixup.h:102