1//===- MCLinkerOptimizationHint.h - LOH interface ---------------*- C++ -*-===//
2//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9//
10// This file declares some helpers classes to handle Linker Optimization Hint
11// (LOH).
12//
13// FIXME: LOH interface supports only MachO format at the moment.
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
17#define LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
18
19#include "llvm/ADT/SmallVector.h"
20#include "llvm/ADT/StringRef.h"
21#include "llvm/ADT/StringSwitch.h"
22#include <cassert>
23#include <cstdint>
24
25namespace llvm {
26
27class MachObjectWriter;
28class MCAsmLayout;
29class MCSymbol;
30class raw_ostream;
31
32/// Linker Optimization Hint Type.
33enum MCLOHType {
34 MCLOH_AdrpAdrp = 0x1u, ///< Adrp xY, _v1@PAGE -> Adrp xY, _v2@PAGE.
35 MCLOH_AdrpLdr = 0x2u, ///< Adrp _v@PAGE -> Ldr _v@PAGEOFF.
36 MCLOH_AdrpAddLdr = 0x3u, ///< Adrp _v@PAGE -> Add _v@PAGEOFF -> Ldr.
37 MCLOH_AdrpLdrGotLdr = 0x4u, ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF -> Ldr.
38 MCLOH_AdrpAddStr = 0x5u, ///< Adrp _v@PAGE -> Add _v@PAGEOFF -> Str.
39 MCLOH_AdrpLdrGotStr = 0x6u, ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF -> Str.
40 MCLOH_AdrpAdd = 0x7u, ///< Adrp _v@PAGE -> Add _v@PAGEOFF.
41 MCLOH_AdrpLdrGot = 0x8u ///< Adrp _v@GOTPAGE -> Ldr _v@GOTPAGEOFF.
42};
43
44static inline StringRef MCLOHDirectiveName() {
45 return StringRef(".loh");
46}
47
48static inline bool isValidMCLOHType(unsigned Kind) {
49 return Kind >= MCLOH_AdrpAdrp && Kind <= MCLOH_AdrpLdrGot;
50}
51
52static inline int MCLOHNameToId(StringRef Name) {
53#define MCLOHCaseNameToId(Name) .Case(#Name, MCLOH_ ## Name)
54 return StringSwitch<int>(Name)
55 MCLOHCaseNameToId(AdrpAdrp)
56 MCLOHCaseNameToId(AdrpLdr)
57 MCLOHCaseNameToId(AdrpAddLdr)
58 MCLOHCaseNameToId(AdrpLdrGotLdr)
59 MCLOHCaseNameToId(AdrpAddStr)
60 MCLOHCaseNameToId(AdrpLdrGotStr)
61 MCLOHCaseNameToId(AdrpAdd)
62 MCLOHCaseNameToId(AdrpLdrGot)
63 .Default(Value: -1);
64#undef MCLOHCaseNameToId
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#undef MCLOHCaseIdToName
81}
82
83static inline int MCLOHIdToNbArgs(MCLOHType Kind) {
84 switch (Kind) {
85 // LOH with two arguments
86 case MCLOH_AdrpAdrp:
87 case MCLOH_AdrpLdr:
88 case MCLOH_AdrpAdd:
89 case MCLOH_AdrpLdrGot:
90 return 2;
91 // LOH with three arguments
92 case MCLOH_AdrpAddLdr:
93 case MCLOH_AdrpLdrGotLdr:
94 case MCLOH_AdrpAddStr:
95 case MCLOH_AdrpLdrGotStr:
96 return 3;
97 }
98 return -1;
99}
100
101/// Store Linker Optimization Hint information (LOH).
102class MCLOHDirective {
103 MCLOHType Kind;
104
105 /// Arguments of this directive. Order matters.
106 SmallVector<MCSymbol *, 3> Args;
107
108 /// Emit this directive in \p OutStream using the information available
109 /// in the given \p ObjWriter and \p Layout to get the address of the
110 /// arguments within the object file.
111 void emit_impl(raw_ostream &OutStream, const MachObjectWriter &ObjWriter,
112 const MCAsmLayout &Layout) const;
113
114public:
115 using LOHArgs = SmallVectorImpl<MCSymbol *>;
116
117 MCLOHDirective(MCLOHType Kind, const LOHArgs &Args)
118 : Kind(Kind), Args(Args.begin(), Args.end()) {
119 assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
120 }
121
122 MCLOHType getKind() const { return Kind; }
123
124 const LOHArgs &getArgs() const { return Args; }
125
126 /// Emit this directive as:
127 /// <kind, numArgs, addr1, ..., addrN>
128 void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const;
129
130 /// Get the size in bytes of this directive if emitted in \p ObjWriter with
131 /// the given \p Layout.
132 uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
133 const MCAsmLayout &Layout) const;
134};
135
136class MCLOHContainer {
137 /// Keep track of the emit size of all the LOHs.
138 mutable uint64_t EmitSize = 0;
139
140 /// Keep track of all LOH directives.
141 SmallVector<MCLOHDirective, 32> Directives;
142
143public:
144 using LOHDirectives = SmallVectorImpl<MCLOHDirective>;
145
146 MCLOHContainer() = default;
147
148 /// Const accessor to the directives.
149 const LOHDirectives &getDirectives() const {
150 return Directives;
151 }
152
153 /// Add the directive of the given kind \p Kind with the given arguments
154 /// \p Args to the container.
155 void addDirective(MCLOHType Kind, const MCLOHDirective::LOHArgs &Args) {
156 Directives.push_back(Elt: MCLOHDirective(Kind, Args));
157 }
158
159 /// Get the size of the directives if emitted.
160 uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
161 const MCAsmLayout &Layout) const {
162 if (!EmitSize) {
163 for (const MCLOHDirective &D : Directives)
164 EmitSize += D.getEmitSize(ObjWriter, Layout);
165 }
166 return EmitSize;
167 }
168
169 /// Emit all Linker Optimization Hint in one big table.
170 /// Each line of the table is emitted by LOHDirective::emit.
171 void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const {
172 for (const MCLOHDirective &D : Directives)
173 D.emit(ObjWriter, Layout);
174 }
175
176 void reset() {
177 Directives.clear();
178 EmitSize = 0;
179 }
180};
181
182// Add types for specialized template using MCSymbol.
183using MCLOHArgs = MCLOHDirective::LOHArgs;
184using MCLOHDirectives = MCLOHContainer::LOHDirectives;
185
186} // end namespace llvm
187
188#endif // LLVM_MC_MCLINKEROPTIMIZATIONHINT_H
189

source code of llvm/include/llvm/MC/MCLinkerOptimizationHint.h