1 //===-- PPCMCTargetDesc.cpp - PowerPC Target Descriptions -----------------===//
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 // This file provides PowerPC specific target descriptions.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "MCTargetDesc/PPCMCTargetDesc.h"
14 #include "MCTargetDesc/PPCInstPrinter.h"
15 #include "MCTargetDesc/PPCMCAsmInfo.h"
16 #include "PPCELFStreamer.h"
17 #include "PPCTargetStreamer.h"
18 #include "TargetInfo/PowerPCTargetInfo.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/BinaryFormat/ELF.h"
23 #include "llvm/MC/MCAssembler.h"
24 #include "llvm/MC/MCAsmBackend.h"
25 #include "llvm/MC/MCCodeEmitter.h"
26 #include "llvm/MC/MCContext.h"
27 #include "llvm/MC/MCDwarf.h"
28 #include "llvm/MC/MCELFStreamer.h"
29 #include "llvm/MC/MCExpr.h"
30 #include "llvm/MC/MCInstrInfo.h"
31 #include "llvm/MC/MCObjectWriter.h"
32 #include "llvm/MC/MCRegisterInfo.h"
33 #include "llvm/MC/MCStreamer.h"
34 #include "llvm/MC/MCSubtargetInfo.h"
35 #include "llvm/MC/MCSymbol.h"
36 #include "llvm/MC/MCSymbolELF.h"
37 #include "llvm/MC/MCSymbolXCOFF.h"
38 #include "llvm/Support/Casting.h"
39 #include "llvm/Support/CodeGen.h"
40 #include "llvm/Support/ErrorHandling.h"
41 #include "llvm/Support/FormattedStream.h"
42 #include "llvm/Support/TargetRegistry.h"
43 #include "llvm/Support/raw_ostream.h"
44 
45 using namespace llvm;
46 
47 #define GET_INSTRINFO_MC_DESC
48 #include "PPCGenInstrInfo.inc"
49 
50 #define GET_SUBTARGETINFO_MC_DESC
51 #include "PPCGenSubtargetInfo.inc"
52 
53 #define GET_REGINFO_MC_DESC
54 #include "PPCGenRegisterInfo.inc"
55 
56 PPCTargetStreamer::PPCTargetStreamer(MCStreamer &S) : MCTargetStreamer(S) {}
57 
58 // Pin the vtable to this file.
59 PPCTargetStreamer::~PPCTargetStreamer() = default;
60 
61 static MCInstrInfo *createPPCMCInstrInfo() {
62   MCInstrInfo *X = new MCInstrInfo();
63   InitPPCMCInstrInfo(X);
64   return X;
65 }
66 
67 static MCRegisterInfo *createPPCMCRegisterInfo(const Triple &TT) {
68   bool isPPC64 =
69       (TT.getArch() == Triple::ppc64 || TT.getArch() == Triple::ppc64le);
70   unsigned Flavour = isPPC64 ? 0 : 1;
71   unsigned RA = isPPC64 ? PPC::LR8 : PPC::LR;
72 
73   MCRegisterInfo *X = new MCRegisterInfo();
74   InitPPCMCRegisterInfo(X, RA, Flavour, Flavour);
75   return X;
76 }
77 
78 static MCSubtargetInfo *createPPCMCSubtargetInfo(const Triple &TT,
79                                                  StringRef CPU, StringRef FS) {
80   return createPPCMCSubtargetInfoImpl(TT, CPU, FS);
81 }
82 
83 static MCAsmInfo *createPPCMCAsmInfo(const MCRegisterInfo &MRI,
84                                      const Triple &TheTriple,
85                                      const MCTargetOptions &Options) {
86   bool isPPC64 = (TheTriple.getArch() == Triple::ppc64 ||
87                   TheTriple.getArch() == Triple::ppc64le);
88 
89   MCAsmInfo *MAI;
90   if (TheTriple.isOSBinFormatXCOFF())
91     MAI = new PPCXCOFFMCAsmInfo(isPPC64, TheTriple);
92   else
93     MAI = new PPCELFMCAsmInfo(isPPC64, TheTriple);
94 
95   // Initial state of the frame pointer is R1.
96   unsigned Reg = isPPC64 ? PPC::X1 : PPC::R1;
97   MCCFIInstruction Inst =
98       MCCFIInstruction::cfiDefCfa(nullptr, MRI.getDwarfRegNum(Reg, true), 0);
99   MAI->addInitialFrameState(Inst);
100 
101   return MAI;
102 }
103 
104 static MCStreamer *createPPCMCStreamer(const Triple &T, MCContext &Context,
105                                        std::unique_ptr<MCAsmBackend> &&MAB,
106                                        std::unique_ptr<MCObjectWriter> &&OW,
107                                        std::unique_ptr<MCCodeEmitter> &&Emitter,
108                                        bool RelaxAll) {
109   return createPPCELFStreamer(Context, std::move(MAB), std::move(OW),
110                               std::move(Emitter));
111 }
112 
113 namespace {
114 
115 class PPCTargetAsmStreamer : public PPCTargetStreamer {
116   formatted_raw_ostream &OS;
117 
118 public:
119   PPCTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS)
120       : PPCTargetStreamer(S), OS(OS) {}
121 
122   void emitTCEntry(const MCSymbol &S) override {
123     if (const MCSymbolXCOFF *XSym = dyn_cast<MCSymbolXCOFF>(&S)) {
124       MCSymbolXCOFF *TCSym =
125           cast<MCSymbolXCOFF>(Streamer.getContext().getOrCreateSymbol(
126               XSym->getSymbolTableName() + "[TC]"));
127       if (TCSym->hasRename())
128         Streamer.emitXCOFFRenameDirective(TCSym, TCSym->getSymbolTableName());
129       OS << "\t.tc " << TCSym->getName() << "," << XSym->getName() << '\n';
130       return;
131     }
132 
133     OS << "\t.tc " << S.getName() << "[TC]," << S.getName() << '\n';
134   }
135 
136   void emitMachine(StringRef CPU) override {
137     OS << "\t.machine " << CPU << '\n';
138   }
139 
140   void emitAbiVersion(int AbiVersion) override {
141     OS << "\t.abiversion " << AbiVersion << '\n';
142   }
143 
144   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
145     const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
146 
147     OS << "\t.localentry\t";
148     S->print(OS, MAI);
149     OS << ", ";
150     LocalOffset->print(OS, MAI);
151     OS << '\n';
152   }
153 };
154 
155 class PPCTargetELFStreamer : public PPCTargetStreamer {
156 public:
157   PPCTargetELFStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
158 
159   MCELFStreamer &getStreamer() {
160     return static_cast<MCELFStreamer &>(Streamer);
161   }
162 
163   void emitTCEntry(const MCSymbol &S) override {
164     // Creates a R_PPC64_TOC relocation
165     Streamer.emitValueToAlignment(8);
166     Streamer.emitSymbolValue(&S, 8);
167   }
168 
169   void emitMachine(StringRef CPU) override {
170     // FIXME: Is there anything to do in here or does this directive only
171     // limit the parser?
172   }
173 
174   void emitAbiVersion(int AbiVersion) override {
175     MCAssembler &MCA = getStreamer().getAssembler();
176     unsigned Flags = MCA.getELFHeaderEFlags();
177     Flags &= ~ELF::EF_PPC64_ABI;
178     Flags |= (AbiVersion & ELF::EF_PPC64_ABI);
179     MCA.setELFHeaderEFlags(Flags);
180   }
181 
182   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
183     MCAssembler &MCA = getStreamer().getAssembler();
184 
185     // encodePPC64LocalEntryOffset will report an error if it cannot
186     // encode LocalOffset.
187     unsigned Encoded = encodePPC64LocalEntryOffset(LocalOffset);
188 
189     unsigned Other = S->getOther();
190     Other &= ~ELF::STO_PPC64_LOCAL_MASK;
191     Other |= Encoded;
192     S->setOther(Other);
193 
194     // For GAS compatibility, unless we already saw a .abiversion directive,
195     // set e_flags to indicate ELFv2 ABI.
196     unsigned Flags = MCA.getELFHeaderEFlags();
197     if ((Flags & ELF::EF_PPC64_ABI) == 0)
198       MCA.setELFHeaderEFlags(Flags | 2);
199   }
200 
201   void emitAssignment(MCSymbol *S, const MCExpr *Value) override {
202     auto *Symbol = cast<MCSymbolELF>(S);
203 
204     // When encoding an assignment to set symbol A to symbol B, also copy
205     // the st_other bits encoding the local entry point offset.
206     if (copyLocalEntry(Symbol, Value))
207       UpdateOther.insert(Symbol);
208     else
209       UpdateOther.erase(Symbol);
210   }
211 
212   void finish() override {
213     for (auto *Sym : UpdateOther)
214       if (Sym->isVariable())
215         copyLocalEntry(Sym, Sym->getVariableValue());
216 
217     // Clear the set of symbols that needs to be updated so the streamer can
218     // be reused without issues.
219     UpdateOther.clear();
220   }
221 
222 private:
223   SmallPtrSet<MCSymbolELF *, 32> UpdateOther;
224 
225   bool copyLocalEntry(MCSymbolELF *D, const MCExpr *S) {
226     auto *Ref = dyn_cast<const MCSymbolRefExpr>(S);
227     if (!Ref)
228       return false;
229     const auto &RhsSym = cast<MCSymbolELF>(Ref->getSymbol());
230     unsigned Other = D->getOther();
231     Other &= ~ELF::STO_PPC64_LOCAL_MASK;
232     Other |= RhsSym.getOther() & ELF::STO_PPC64_LOCAL_MASK;
233     D->setOther(Other);
234     return true;
235   }
236 
237   unsigned encodePPC64LocalEntryOffset(const MCExpr *LocalOffset) {
238     MCAssembler &MCA = getStreamer().getAssembler();
239     int64_t Offset;
240     if (!LocalOffset->evaluateAsAbsolute(Offset, MCA))
241       MCA.getContext().reportFatalError(
242           LocalOffset->getLoc(), ".localentry expression must be absolute.");
243 
244     switch (Offset) {
245     default:
246       MCA.getContext().reportFatalError(
247           LocalOffset->getLoc(),
248           ".localentry expression is not a valid power of 2.");
249     case 0:
250       return 0;
251     case 1:
252       return 1 << ELF::STO_PPC64_LOCAL_BIT;
253     case 4:
254     case 8:
255     case 16:
256     case 32:
257     case 64:
258       return (int)Log2(Offset) << (int)ELF::STO_PPC64_LOCAL_BIT;
259     }
260   }
261 };
262 
263 class PPCTargetMachOStreamer : public PPCTargetStreamer {
264 public:
265   PPCTargetMachOStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
266 
267   void emitTCEntry(const MCSymbol &S) override {
268     llvm_unreachable("Unknown pseudo-op: .tc");
269   }
270 
271   void emitMachine(StringRef CPU) override {
272     // FIXME: We should update the CPUType, CPUSubType in the Object file if
273     // the new values are different from the defaults.
274   }
275 
276   void emitAbiVersion(int AbiVersion) override {
277     llvm_unreachable("Unknown pseudo-op: .abiversion");
278   }
279 
280   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
281     llvm_unreachable("Unknown pseudo-op: .localentry");
282   }
283 };
284 
285 class PPCTargetXCOFFStreamer : public PPCTargetStreamer {
286 public:
287   PPCTargetXCOFFStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
288 
289   void emitTCEntry(const MCSymbol &S) override {
290     const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
291     const unsigned PointerSize = MAI->getCodePointerSize();
292     Streamer.emitValueToAlignment(PointerSize);
293     Streamer.emitSymbolValue(&S, PointerSize);
294   }
295 
296   void emitMachine(StringRef CPU) override {
297     llvm_unreachable("Machine pseudo-ops are invalid for XCOFF.");
298   }
299 
300   void emitAbiVersion(int AbiVersion) override {
301     llvm_unreachable("ABI-version pseudo-ops are invalid for XCOFF.");
302   }
303 
304   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
305     llvm_unreachable("Local-entry pseudo-ops are invalid for XCOFF.");
306   }
307 };
308 
309 } // end anonymous namespace
310 
311 static MCTargetStreamer *createAsmTargetStreamer(MCStreamer &S,
312                                                  formatted_raw_ostream &OS,
313                                                  MCInstPrinter *InstPrint,
314                                                  bool isVerboseAsm) {
315   return new PPCTargetAsmStreamer(S, OS);
316 }
317 
318 static MCTargetStreamer *
319 createObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
320   const Triple &TT = STI.getTargetTriple();
321   if (TT.isOSBinFormatELF())
322     return new PPCTargetELFStreamer(S);
323   if (TT.isOSBinFormatXCOFF())
324     return new PPCTargetXCOFFStreamer(S);
325   return new PPCTargetMachOStreamer(S);
326 }
327 
328 static MCInstPrinter *createPPCMCInstPrinter(const Triple &T,
329                                              unsigned SyntaxVariant,
330                                              const MCAsmInfo &MAI,
331                                              const MCInstrInfo &MII,
332                                              const MCRegisterInfo &MRI) {
333   return new PPCInstPrinter(MAI, MII, MRI, T);
334 }
335 
336 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializePowerPCTargetMC() {
337   for (Target *T :
338        {&getThePPC32Target(), &getThePPC64Target(), &getThePPC64LETarget()}) {
339     // Register the MC asm info.
340     RegisterMCAsmInfoFn C(*T, createPPCMCAsmInfo);
341 
342     // Register the MC instruction info.
343     TargetRegistry::RegisterMCInstrInfo(*T, createPPCMCInstrInfo);
344 
345     // Register the MC register info.
346     TargetRegistry::RegisterMCRegInfo(*T, createPPCMCRegisterInfo);
347 
348     // Register the MC subtarget info.
349     TargetRegistry::RegisterMCSubtargetInfo(*T, createPPCMCSubtargetInfo);
350 
351     // Register the MC Code Emitter
352     TargetRegistry::RegisterMCCodeEmitter(*T, createPPCMCCodeEmitter);
353 
354     // Register the asm backend.
355     TargetRegistry::RegisterMCAsmBackend(*T, createPPCAsmBackend);
356 
357     // Register the elf streamer.
358     TargetRegistry::RegisterELFStreamer(*T, createPPCMCStreamer);
359 
360     // Register the object target streamer.
361     TargetRegistry::RegisterObjectTargetStreamer(*T,
362                                                  createObjectTargetStreamer);
363 
364     // Register the asm target streamer.
365     TargetRegistry::RegisterAsmTargetStreamer(*T, createAsmTargetStreamer);
366 
367     // Register the MCInstPrinter.
368     TargetRegistry::RegisterMCInstPrinter(*T, createPPCMCInstPrinter);
369   }
370 }
371