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1 : //===- lib/MC/AArch64ELFStreamer.cpp - ELF Object Output for AArch64 ------===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 : //
10 : // This file assembles .s files and emits AArch64 ELF .o object files. Different
11 : // from generic ELF streamer in emitting mapping symbols ($x and $d) to delimit
12 : // regions of data and code.
13 : //
14 : //===----------------------------------------------------------------------===//
15 :
16 : #include "AArch64TargetStreamer.h"
17 : #include "AArch64WinCOFFStreamer.h"
18 : #include "llvm/ADT/DenseMap.h"
19 : #include "llvm/ADT/StringRef.h"
20 : #include "llvm/ADT/Triple.h"
21 : #include "llvm/ADT/Twine.h"
22 : #include "llvm/BinaryFormat/ELF.h"
23 : #include "llvm/MC/MCAsmBackend.h"
24 : #include "llvm/MC/MCAssembler.h"
25 : #include "llvm/MC/MCCodeEmitter.h"
26 : #include "llvm/MC/MCContext.h"
27 : #include "llvm/MC/MCELFStreamer.h"
28 : #include "llvm/MC/MCExpr.h"
29 : #include "llvm/MC/MCInst.h"
30 : #include "llvm/MC/MCObjectWriter.h"
31 : #include "llvm/MC/MCSection.h"
32 : #include "llvm/MC/MCStreamer.h"
33 : #include "llvm/MC/MCSubtargetInfo.h"
34 : #include "llvm/MC/MCSymbolELF.h"
35 : #include "llvm/MC/MCWinCOFFStreamer.h"
36 : #include "llvm/Support/Casting.h"
37 : #include "llvm/Support/FormattedStream.h"
38 : #include "llvm/Support/raw_ostream.h"
39 :
40 : using namespace llvm;
41 :
42 : namespace {
43 :
44 : class AArch64ELFStreamer;
45 :
46 : class AArch64TargetAsmStreamer : public AArch64TargetStreamer {
47 : formatted_raw_ostream &OS;
48 :
49 : void emitInst(uint32_t Inst) override;
50 :
51 : public:
52 : AArch64TargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS);
53 : };
54 :
55 : AArch64TargetAsmStreamer::AArch64TargetAsmStreamer(MCStreamer &S,
56 2520 : formatted_raw_ostream &OS)
57 2520 : : AArch64TargetStreamer(S), OS(OS) {}
58 :
59 8 : void AArch64TargetAsmStreamer::emitInst(uint32_t Inst) {
60 8 : OS << "\t.inst\t0x" << Twine::utohexstr(Inst) << "\n";
61 8 : }
62 :
63 : class AArch64TargetELFStreamer : public AArch64TargetStreamer {
64 : private:
65 : AArch64ELFStreamer &getStreamer();
66 :
67 : void emitInst(uint32_t Inst) override;
68 :
69 : public:
70 829 : AArch64TargetELFStreamer(MCStreamer &S) : AArch64TargetStreamer(S) {}
71 : };
72 :
73 : /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
74 : /// the appropriate points in the object files. These symbols are defined in the
75 : /// AArch64 ELF ABI:
76 : /// infocenter.arm.com/help/topic/com.arm.doc.ihi0056a/IHI0056A_aaelf64.pdf
77 : ///
78 : /// In brief: $x or $d should be emitted at the start of each contiguous region
79 : /// of A64 code or data in a section. In practice, this emission does not rely
80 : /// on explicit assembler directives but on inherent properties of the
81 : /// directives doing the emission (e.g. ".byte" is data, "add x0, x0, x0" an
82 : /// instruction).
83 : ///
84 : /// As a result this system is orthogonal to the DataRegion infrastructure used
85 : /// by MachO. Beware!
86 : class AArch64ELFStreamer : public MCELFStreamer {
87 : public:
88 : friend class AArch64TargetELFStreamer;
89 :
90 829 : AArch64ELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
91 : std::unique_ptr<MCObjectWriter> OW,
92 : std::unique_ptr<MCCodeEmitter> Emitter)
93 829 : : MCELFStreamer(Context, std::move(TAB), std::move(OW),
94 : std::move(Emitter)),
95 2487 : MappingSymbolCounter(0), LastEMS(EMS_None) {}
96 :
97 1179 : void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
98 : // We have to keep track of the mapping symbol state of any sections we
99 : // use. Each one should start off as EMS_None, which is provided as the
100 : // default constructor by DenseMap::lookup.
101 1179 : LastMappingSymbols[getPreviousSection().first] = LastEMS;
102 1179 : LastEMS = LastMappingSymbols.lookup(Section);
103 :
104 1179 : MCELFStreamer::ChangeSection(Section, Subsection);
105 1179 : }
106 :
107 : // Reset state between object emissions
108 25 : void reset() override {
109 25 : MappingSymbolCounter = 0;
110 : MCELFStreamer::reset();
111 25 : LastMappingSymbols.clear();
112 25 : LastEMS = EMS_None;
113 25 : }
114 :
115 : /// This function is the one used to emit instruction data into the ELF
116 : /// streamer. We override it to add the appropriate mapping symbol if
117 : /// necessary.
118 11160 : void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
119 : bool) override {
120 : EmitA64MappingSymbol();
121 11160 : MCELFStreamer::EmitInstruction(Inst, STI);
122 11160 : }
123 :
124 : /// Emit a 32-bit value as an instruction. This is only used for the .inst
125 : /// directive, EmitInstruction should be used in other cases.
126 4 : void emitInst(uint32_t Inst) {
127 : char Buffer[4];
128 :
129 : // We can't just use EmitIntValue here, as that will emit a data mapping
130 : // symbol, and swap the endianness on big-endian systems (instructions are
131 : // always little-endian).
132 20 : for (unsigned I = 0; I < 4; ++I) {
133 16 : Buffer[I] = uint8_t(Inst);
134 16 : Inst >>= 8;
135 : }
136 :
137 : EmitA64MappingSymbol();
138 8 : MCELFStreamer::EmitBytes(StringRef(Buffer, 4));
139 4 : }
140 :
141 : /// This is one of the functions used to emit data into an ELF section, so the
142 : /// AArch64 streamer overrides it to add the appropriate mapping symbol ($d)
143 : /// if necessary.
144 2495 : void EmitBytes(StringRef Data) override {
145 : EmitDataMappingSymbol();
146 2495 : MCELFStreamer::EmitBytes(Data);
147 2495 : }
148 :
149 : /// This is one of the functions used to emit data into an ELF section, so the
150 : /// AArch64 streamer overrides it to add the appropriate mapping symbol ($d)
151 : /// if necessary.
152 495 : void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
153 : EmitDataMappingSymbol();
154 495 : MCELFStreamer::EmitValueImpl(Value, Size, Loc);
155 495 : }
156 :
157 97 : void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
158 : SMLoc Loc) override {
159 : EmitDataMappingSymbol();
160 97 : MCObjectStreamer::emitFill(NumBytes, FillValue, Loc);
161 97 : }
162 : private:
163 : enum ElfMappingSymbol {
164 : EMS_None,
165 : EMS_A64,
166 : EMS_Data
167 : };
168 :
169 : void EmitDataMappingSymbol() {
170 3087 : if (LastEMS == EMS_Data)
171 : return;
172 264 : EmitMappingSymbol("$d");
173 264 : LastEMS = EMS_Data;
174 : }
175 :
176 : void EmitA64MappingSymbol() {
177 11164 : if (LastEMS == EMS_A64)
178 : return;
179 863 : EmitMappingSymbol("$x");
180 863 : LastEMS = EMS_A64;
181 : }
182 :
183 1127 : void EmitMappingSymbol(StringRef Name) {
184 1127 : auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
185 1127 : Name + "." + Twine(MappingSymbolCounter++)));
186 1127 : EmitLabel(Symbol);
187 1127 : Symbol->setType(ELF::STT_NOTYPE);
188 1127 : Symbol->setBinding(ELF::STB_LOCAL);
189 : Symbol->setExternal(false);
190 1127 : }
191 :
192 : int64_t MappingSymbolCounter;
193 :
194 : DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
195 : ElfMappingSymbol LastEMS;
196 : };
197 :
198 : } // end anonymous namespace
199 :
200 0 : AArch64ELFStreamer &AArch64TargetELFStreamer::getStreamer() {
201 0 : return static_cast<AArch64ELFStreamer &>(Streamer);
202 : }
203 :
204 4 : void AArch64TargetELFStreamer::emitInst(uint32_t Inst) {
205 4 : getStreamer().emitInst(Inst);
206 4 : }
207 :
208 : namespace llvm {
209 :
210 2520 : MCTargetStreamer *createAArch64AsmTargetStreamer(MCStreamer &S,
211 : formatted_raw_ostream &OS,
212 : MCInstPrinter *InstPrint,
213 : bool isVerboseAsm) {
214 2520 : return new AArch64TargetAsmStreamer(S, OS);
215 : }
216 :
217 829 : MCELFStreamer *createAArch64ELFStreamer(MCContext &Context,
218 : std::unique_ptr<MCAsmBackend> TAB,
219 : std::unique_ptr<MCObjectWriter> OW,
220 : std::unique_ptr<MCCodeEmitter> Emitter,
221 : bool RelaxAll) {
222 : AArch64ELFStreamer *S = new AArch64ELFStreamer(
223 1658 : Context, std::move(TAB), std::move(OW), std::move(Emitter));
224 829 : if (RelaxAll)
225 : S->getAssembler().setRelaxAll(true);
226 829 : return S;
227 : }
228 :
229 : MCTargetStreamer *
230 880 : createAArch64ObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
231 : const Triple &TT = STI.getTargetTriple();
232 880 : if (TT.isOSBinFormatELF())
233 1658 : return new AArch64TargetELFStreamer(S);
234 51 : if (TT.isOSBinFormatCOFF())
235 32 : return new AArch64TargetWinCOFFStreamer(S);
236 : return nullptr;
237 : }
238 :
239 : } // end namespace llvm
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