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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/MC/MCMachObjectWriter.h"
24 #include "llvm/Support/raw_ostream.h"
25
26 namespace llvm {
27
28 // Forward declarations.
29 class MCAsmLayout;
30 class MCSymbol;
31
32 /// Linker Optimization Hint Type.
33 enum 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
44 static inline StringRef MCLOHDirectiveName() {
45 return StringRef(".loh");
46 }
47
48 static inline bool isValidMCLOHType(unsigned Kind) {
49 return Kind >= MCLOH_AdrpAdrp && Kind <= MCLOH_AdrpLdrGot;
50 }
51
52 static 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(-1);
64 }
65
66 static inline StringRef MCLOHIdToName(MCLOHType Kind) {
67 #define MCLOHCaseIdToName(Name) case MCLOH_ ## Name: return StringRef(#Name);
68 switch (Kind) {
69 MCLOHCaseIdToName(AdrpAdrp);
70 MCLOHCaseIdToName(AdrpLdr);
71 MCLOHCaseIdToName(AdrpAddLdr);
72 MCLOHCaseIdToName(AdrpLdrGotLdr);
73 MCLOHCaseIdToName(AdrpAddStr);
74 MCLOHCaseIdToName(AdrpLdrGotStr);
75 MCLOHCaseIdToName(AdrpAdd);
76 MCLOHCaseIdToName(AdrpLdrGot);
77 }
78 return StringRef();
79 }
80
81 static inline int MCLOHIdToNbArgs(MCLOHType Kind) {
82 switch (Kind) {
83 // LOH with two arguments
84 case MCLOH_AdrpAdrp:
85 case MCLOH_AdrpLdr:
86 case MCLOH_AdrpAdd:
87 case MCLOH_AdrpLdrGot:
88 return 2;
89 // LOH with three arguments
90 case MCLOH_AdrpAddLdr:
91 case MCLOH_AdrpLdrGotLdr:
92 case MCLOH_AdrpAddStr:
93 case MCLOH_AdrpLdrGotStr:
94 return 3;
95 }
96 return -1;
97 }
98
99 /// Store Linker Optimization Hint information (LOH).
100 class MCLOHDirective {
101 MCLOHType Kind;
102
103 /// Arguments of this directive. Order matters.
104 SmallVector<MCSymbol *, 3> Args;
105
106 /// Emit this directive in @p OutStream using the information available
107 /// in the given @p ObjWriter and @p Layout to get the address of the
108 /// arguments within the object file.
109 void Emit_impl(raw_ostream &OutStream, const MachObjectWriter &ObjWriter,
110 const MCAsmLayout &Layout) const;
111
112 public:
113 typedef SmallVectorImpl<MCSymbol *> LOHArgs;
114
115 MCLOHDirective(MCLOHType Kind, const LOHArgs &Args)
116 : Kind(Kind), Args(Args.begin(), Args.end()) {
117 assert(isValidMCLOHType(Kind) && "Invalid LOH directive type!");
118 }
119
120 MCLOHType getKind() const { return Kind; }
121
122 const LOHArgs &getArgs() const { return Args; }
123
124 /// Emit this directive as:
125 /// <kind, numArgs, addr1, ..., addrN>
126 void Emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const {
127 raw_ostream &OutStream = ObjWriter.getStream();
128 Emit_impl(OutStream, ObjWriter, Layout);
129 }
130
131 /// Get the size in bytes of this directive if emitted in @p ObjWriter with
132 /// the given @p Layout.
133 uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
134 const MCAsmLayout &Layout) const {
135 class raw_counting_ostream : public raw_ostream {
136 uint64_t Count;
137
138 void write_impl(const char *, size_t size) override { Count += size; }
139
140 uint64_t current_pos() const override { return Count; }
141
142 public:
143 raw_counting_ostream() : Count(0) {}
144 ~raw_counting_ostream() { flush(); }
145 };
146
147 raw_counting_ostream OutStream;
148 Emit_impl(OutStream, ObjWriter, Layout);
149 return OutStream.tell();
150 }
151 };
152
153 class MCLOHContainer {
154 /// Keep track of the emit size of all the LOHs.
155 mutable uint64_t EmitSize;
156
157 /// Keep track of all LOH directives.
158 SmallVector<MCLOHDirective, 32> Directives;
159
160 public:
161 typedef SmallVectorImpl<MCLOHDirective> LOHDirectives;
162
163 MCLOHContainer() : EmitSize(0) {};
164
165 /// Const accessor to the directives.
166 const LOHDirectives &getDirectives() const {
167 return Directives;
168 }
169
170 /// Add the directive of the given kind @p Kind with the given arguments
171 /// @p Args to the container.
172 void addDirective(MCLOHType Kind, const MCLOHDirective::LOHArgs &Args) {
173 Directives.push_back(MCLOHDirective(Kind, Args));
174 }
175
176 /// Get the size of the directives if emitted.
177 uint64_t getEmitSize(const MachObjectWriter &ObjWriter,
178 const MCAsmLayout &Layout) const {
179 if (!EmitSize) {
180 for (const MCLOHDirective &D : Directives)
181 EmitSize += D.getEmitSize(ObjWriter, Layout);
182 }
183 return EmitSize;
184 }
185
186 /// Emit all Linker Optimization Hint in one big table.
187 /// Each line of the table is emitted by LOHDirective::Emit.
188 void Emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const {
189 for (const MCLOHDirective &D : Directives)
190 D.Emit(ObjWriter, Layout);
191 }
192
193 void reset() {
194 Directives.clear();
195 EmitSize = 0;
196 }
197 };
198
199 // Add types for specialized template using MCSymbol.
200 typedef MCLOHDirective::LOHArgs MCLOHArgs;
201 typedef MCLOHContainer::LOHDirectives MCLOHDirectives;
202
203 } // end namespace llvm
204
205 #endif