1//===- MCLinkerOptimizationHint.h - LOH interface ---------------*- C++ -*-===//
2//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is distributed under the University of Illinois Open Source
7// License. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10//
11// This file declares some helpers classes to handle Linker Optimization Hint
12// (LOH).
13//
14// FIXME: LOH interface supports only MachO format at the moment.
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
18#define LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
19
20#include "llvm/ADT/SmallVector.h"
21#include "llvm/ADT/StringRef.h"
22#include "llvm/ADT/StringSwitch.h"
23#include "llvm/Support/raw_ostream.h"
24#include <cassert>
25#include <cstdint>
26
27namespace llvm {
28
29class MachObjectWriter;
30class MCAsmLayout;
31class MCSymbol;
32
33/// Linker Optimization Hint Type.
34enum MCLOHType {
35  MCLOH_AdrpAdrp = 0x1u,      ///< Adrp xY, _v1@PAGE -> Adrp xY, _v2@PAGE.
36  MCLOH_AdrpLdr = 0x2u,       ///< Adrp _v@PAGE -> Ldr _v@PAGEOFF.
37  MCLOH_AdrpAddLdr = 0x3u,    ///< Adrp _v@PAGE -> Add _v@PAGEOFF -> Ldr.
38  MCLOH_AdrpLdrGotLdr = 0x4u, ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF -> Ldr.
39  MCLOH_AdrpAddStr = 0x5u,    ///< Adrp _v@PAGE -> Add _v@PAGEOFF -> Str.
40  MCLOH_AdrpLdrGotStr = 0x6u, ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF -> Str.
41  MCLOH_AdrpAdd = 0x7u,       ///< Adrp _v@PAGE -> Add _v@PAGEOFF.
42  MCLOH_AdrpLdrGot = 0x8u     ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF.
43};
44
45static inline StringRef MCLOHDirectiveName() {
46  return StringRef(".loh");
47}
48
49static inline bool isValidMCLOHType(unsigned Kind) {
50  return Kind >= MCLOH_AdrpAdrp && Kind <= MCLOH_AdrpLdrGot;
51}
52
53static inline int MCLOHNameToId(StringRef Name) {
54#define MCLOHCaseNameToId(Name)     .Case(#Name, MCLOH_ ## Name)
55  return StringSwitch<int>(Name)
56    MCLOHCaseNameToId(AdrpAdrp)
57    MCLOHCaseNameToId(AdrpLdr)
58    MCLOHCaseNameToId(AdrpAddLdr)
59    MCLOHCaseNameToId(AdrpLdrGotLdr)
60    MCLOHCaseNameToId(AdrpAddStr)
61    MCLOHCaseNameToId(AdrpLdrGotStr)
62    MCLOHCaseNameToId(AdrpAdd)
63    MCLOHCaseNameToId(AdrpLdrGot)
64    .Default(-1);
65}
66
67static inline StringRef MCLOHIdToName(MCLOHType Kind) {
68#define MCLOHCaseIdToName(Name)      case MCLOH_ ## Name: return StringRef(#Name);
69  switch (Kind) {
70    MCLOHCaseIdToName(AdrpAdrp);
71    MCLOHCaseIdToName(AdrpLdr);
72    MCLOHCaseIdToName(AdrpAddLdr);
73    MCLOHCaseIdToName(AdrpLdrGotLdr);
74    MCLOHCaseIdToName(AdrpAddStr);
75    MCLOHCaseIdToName(AdrpLdrGotStr);
76    MCLOHCaseIdToName(AdrpAdd);
77    MCLOHCaseIdToName(AdrpLdrGot);
78  }
79  return StringRef();
80}
81
82static inline int MCLOHIdToNbArgs(MCLOHType Kind) {
83  switch (Kind) {
84    // LOH with two arguments
85  case MCLOH_AdrpAdrp:
86  case MCLOH_AdrpLdr:
87  case MCLOH_AdrpAdd:
88  case MCLOH_AdrpLdrGot:
89    return 2;
90    // LOH with three arguments
91  case MCLOH_AdrpAddLdr:
92  case MCLOH_AdrpLdrGotLdr:
93  case MCLOH_AdrpAddStr:
94  case MCLOH_AdrpLdrGotStr:
95    return 3;
96  }
97  return -1;
98}
99
100/// Store Linker Optimization Hint information (LOH).
101class MCLOHDirective {
102  MCLOHType Kind;
103
104  /// Arguments of this directive. Order matters.
105  SmallVector<MCSymbol *, 3> Args;
106
107  /// Emit this directive in \p OutStream using the information available
108  /// in the given \p ObjWriter and \p Layout to get the address of the
109  /// arguments within the object file.
110  void emit_impl(raw_ostream &OutStream, const MachObjectWriter &ObjWriter,
111                 const MCAsmLayout &Layout) const;
112
113public:
114  using LOHArgs = SmallVectorImpl<MCSymbol *>;
115
116  MCLOHDirective(MCLOHType Kind, const LOHArgs &Args)
117      : Kind(Kind), Args(Args.begin(), Args.end()) {
118    assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
119  }
120
121  MCLOHType getKind() const { return Kind; }
122
123  const LOHArgs &getArgs() const { return Args; }
124
125  /// Emit this directive as:
126  /// <kind, numArgs, addr1, ..., addrN>
127  void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const;
128
129  /// Get the size in bytes of this directive if emitted in \p ObjWriter with
130  /// the given \p Layout.
131  uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
132                       const MCAsmLayout &Layout) const;
133};
134
135class MCLOHContainer {
136  /// Keep track of the emit size of all the LOHs.
137  mutable uint64_t EmitSize = 0;
138
139  /// Keep track of all LOH directives.
140  SmallVector<MCLOHDirective, 32> Directives;
141
142public:
143  using LOHDirectives = SmallVectorImpl<MCLOHDirective>;
144
145  MCLOHContainer() = default;
146
147  /// Const accessor to the directives.
148  const LOHDirectives &getDirectives() const {
149    return Directives;
150  }
151
152  /// Add the directive of the given kind \p Kind with the given arguments
153  /// \p Args to the container.
154  void addDirective(MCLOHType Kind, const MCLOHDirective::LOHArgs &Args) {
155    Directives.push_back(MCLOHDirective(Kind, Args));
156  }
157
158  /// Get the size of the directives if emitted.
159  uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
160                       const MCAsmLayout &Layout) const {
161    if (!EmitSize) {
162      for (const MCLOHDirective &D : Directives)
163        EmitSize += D.getEmitSize(ObjWriter, Layout);
164    }
165    return EmitSize;
166  }
167
168  /// Emit all Linker Optimization Hint in one big table.
169  /// Each line of the table is emitted by LOHDirective::emit.
170  void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const {
171    for (const MCLOHDirective &D : Directives)
172      D.emit(ObjWriter, Layout);
173  }
174
175  void reset() {
176    Directives.clear();
177    EmitSize = 0;
178  }
179};
180
181// Add types for specialized template using MCSymbol.
182using MCLOHArgs = MCLOHDirective::LOHArgs;
183using MCLOHDirectives = MCLOHContainer::LOHDirectives;
184
185} // end namespace llvm
186
187#endif // LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
188