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/MCAsmBackend.h"
24 #include "llvm/MC/MCAssembler.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/MCSectionXCOFF.h"
34 #include "llvm/MC/MCStreamer.h"
35 #include "llvm/MC/MCSubtargetInfo.h"
36 #include "llvm/MC/MCSymbol.h"
37 #include "llvm/MC/MCSymbolELF.h"
38 #include "llvm/MC/MCSymbolXCOFF.h"
39 #include "llvm/Support/Casting.h"
40 #include "llvm/Support/CodeGen.h"
41 #include "llvm/Support/ErrorHandling.h"
42 #include "llvm/Support/FormattedStream.h"
43 #include "llvm/Support/TargetRegistry.h"
44 #include "llvm/Support/raw_ostream.h"
45 
46 using namespace llvm;
47 
48 #define GET_INSTRINFO_MC_DESC
49 #include "PPCGenInstrInfo.inc"
50 
51 #define GET_SUBTARGETINFO_MC_DESC
52 #include "PPCGenSubtargetInfo.inc"
53 
54 #define GET_REGINFO_MC_DESC
55 #include "PPCGenRegisterInfo.inc"
56 
57 PPCTargetStreamer::PPCTargetStreamer(MCStreamer &S) : MCTargetStreamer(S) {}
58 
59 // Pin the vtable to this file.
60 PPCTargetStreamer::~PPCTargetStreamer() = default;
61 
62 static MCInstrInfo *createPPCMCInstrInfo() {
63   MCInstrInfo *X = new MCInstrInfo();
64   InitPPCMCInstrInfo(X);
65   return X;
66 }
67 
68 static MCRegisterInfo *createPPCMCRegisterInfo(const Triple &TT) {
69   bool isPPC64 =
70       (TT.getArch() == Triple::ppc64 || TT.getArch() == Triple::ppc64le);
71   unsigned Flavour = isPPC64 ? 0 : 1;
72   unsigned RA = isPPC64 ? PPC::LR8 : PPC::LR;
73 
74   MCRegisterInfo *X = new MCRegisterInfo();
75   InitPPCMCRegisterInfo(X, RA, Flavour, Flavour);
76   return X;
77 }
78 
79 static MCSubtargetInfo *createPPCMCSubtargetInfo(const Triple &TT,
80                                                  StringRef CPU, StringRef FS) {
81   // Set some default feature to MC layer.
82   std::string FullFS = std::string(FS);
83 
84   if (TT.isOSAIX()) {
85     if (!FullFS.empty())
86       FullFS = "+aix," + FullFS;
87     else
88       FullFS = "+aix";
89   }
90 
91   return createPPCMCSubtargetInfoImpl(TT, CPU, /*TuneCPU*/ CPU, FullFS);
92 }
93 
94 static MCAsmInfo *createPPCMCAsmInfo(const MCRegisterInfo &MRI,
95                                      const Triple &TheTriple,
96                                      const MCTargetOptions &Options) {
97   bool isPPC64 = (TheTriple.getArch() == Triple::ppc64 ||
98                   TheTriple.getArch() == Triple::ppc64le);
99 
100   MCAsmInfo *MAI;
101   if (TheTriple.isOSBinFormatXCOFF())
102     MAI = new PPCXCOFFMCAsmInfo(isPPC64, TheTriple);
103   else
104     MAI = new PPCELFMCAsmInfo(isPPC64, TheTriple);
105 
106   // Initial state of the frame pointer is R1.
107   unsigned Reg = isPPC64 ? PPC::X1 : PPC::R1;
108   MCCFIInstruction Inst =
109       MCCFIInstruction::cfiDefCfa(nullptr, MRI.getDwarfRegNum(Reg, true), 0);
110   MAI->addInitialFrameState(Inst);
111 
112   return MAI;
113 }
114 
115 static MCStreamer *createPPCMCStreamer(const Triple &T, MCContext &Context,
116                                        std::unique_ptr<MCAsmBackend> &&MAB,
117                                        std::unique_ptr<MCObjectWriter> &&OW,
118                                        std::unique_ptr<MCCodeEmitter> &&Emitter,
119                                        bool RelaxAll) {
120   return createPPCELFStreamer(Context, std::move(MAB), std::move(OW),
121                               std::move(Emitter));
122 }
123 
124 namespace {
125 
126 class PPCTargetAsmStreamer : public PPCTargetStreamer {
127   formatted_raw_ostream &OS;
128 
129 public:
130   PPCTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS)
131       : PPCTargetStreamer(S), OS(OS) {}
132 
133   void emitTCEntry(const MCSymbol &S,
134                    MCSymbolRefExpr::VariantKind Kind) override {
135     if (const MCSymbolXCOFF *XSym = dyn_cast<MCSymbolXCOFF>(&S)) {
136       MCSymbolXCOFF *TCSym =
137           cast<MCSectionXCOFF>(Streamer.getCurrentSectionOnly())
138               ->getQualNameSymbol();
139       // If the variant kind is TLSGD the entry represents the region handle for
140       // the symbol, we prefix the name with a dot and we add the @m
141       // relocation specifier.
142       if (Kind == MCSymbolRefExpr::VariantKind::VK_PPC_TLSGD)
143         OS << "\t.tc ." << TCSym->getName() << "," << XSym->getName() << "@m\n";
144       else
145         OS << "\t.tc " << TCSym->getName() << "," << XSym->getName() << '\n';
146 
147       if (TCSym->hasRename())
148         Streamer.emitXCOFFRenameDirective(TCSym, TCSym->getSymbolTableName());
149       return;
150     }
151 
152     OS << "\t.tc " << S.getName() << "[TC]," << S.getName() << '\n';
153   }
154 
155   void emitMachine(StringRef CPU) override {
156     OS << "\t.machine " << CPU << '\n';
157   }
158 
159   void emitAbiVersion(int AbiVersion) override {
160     OS << "\t.abiversion " << AbiVersion << '\n';
161   }
162 
163   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
164     const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
165 
166     OS << "\t.localentry\t";
167     S->print(OS, MAI);
168     OS << ", ";
169     LocalOffset->print(OS, MAI);
170     OS << '\n';
171   }
172 };
173 
174 class PPCTargetELFStreamer : public PPCTargetStreamer {
175 public:
176   PPCTargetELFStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
177 
178   MCELFStreamer &getStreamer() {
179     return static_cast<MCELFStreamer &>(Streamer);
180   }
181 
182   void emitTCEntry(const MCSymbol &S,
183                    MCSymbolRefExpr::VariantKind Kind) override {
184     // Creates a R_PPC64_TOC relocation
185     Streamer.emitValueToAlignment(8);
186     Streamer.emitSymbolValue(&S, 8);
187   }
188 
189   void emitMachine(StringRef CPU) override {
190     // FIXME: Is there anything to do in here or does this directive only
191     // limit the parser?
192   }
193 
194   void emitAbiVersion(int AbiVersion) override {
195     MCAssembler &MCA = getStreamer().getAssembler();
196     unsigned Flags = MCA.getELFHeaderEFlags();
197     Flags &= ~ELF::EF_PPC64_ABI;
198     Flags |= (AbiVersion & ELF::EF_PPC64_ABI);
199     MCA.setELFHeaderEFlags(Flags);
200   }
201 
202   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
203     MCAssembler &MCA = getStreamer().getAssembler();
204 
205     // encodePPC64LocalEntryOffset will report an error if it cannot
206     // encode LocalOffset.
207     unsigned Encoded = encodePPC64LocalEntryOffset(LocalOffset);
208 
209     unsigned Other = S->getOther();
210     Other &= ~ELF::STO_PPC64_LOCAL_MASK;
211     Other |= Encoded;
212     S->setOther(Other);
213 
214     // For GAS compatibility, unless we already saw a .abiversion directive,
215     // set e_flags to indicate ELFv2 ABI.
216     unsigned Flags = MCA.getELFHeaderEFlags();
217     if ((Flags & ELF::EF_PPC64_ABI) == 0)
218       MCA.setELFHeaderEFlags(Flags | 2);
219   }
220 
221   void emitAssignment(MCSymbol *S, const MCExpr *Value) override {
222     auto *Symbol = cast<MCSymbolELF>(S);
223 
224     // When encoding an assignment to set symbol A to symbol B, also copy
225     // the st_other bits encoding the local entry point offset.
226     if (copyLocalEntry(Symbol, Value))
227       UpdateOther.insert(Symbol);
228     else
229       UpdateOther.erase(Symbol);
230   }
231 
232   void finish() override {
233     for (auto *Sym : UpdateOther)
234       if (Sym->isVariable())
235         copyLocalEntry(Sym, Sym->getVariableValue());
236 
237     // Clear the set of symbols that needs to be updated so the streamer can
238     // be reused without issues.
239     UpdateOther.clear();
240   }
241 
242 private:
243   SmallPtrSet<MCSymbolELF *, 32> UpdateOther;
244 
245   bool copyLocalEntry(MCSymbolELF *D, const MCExpr *S) {
246     auto *Ref = dyn_cast<const MCSymbolRefExpr>(S);
247     if (!Ref)
248       return false;
249     const auto &RhsSym = cast<MCSymbolELF>(Ref->getSymbol());
250     unsigned Other = D->getOther();
251     Other &= ~ELF::STO_PPC64_LOCAL_MASK;
252     Other |= RhsSym.getOther() & ELF::STO_PPC64_LOCAL_MASK;
253     D->setOther(Other);
254     return true;
255   }
256 
257   unsigned encodePPC64LocalEntryOffset(const MCExpr *LocalOffset) {
258     MCAssembler &MCA = getStreamer().getAssembler();
259     int64_t Offset;
260     if (!LocalOffset->evaluateAsAbsolute(Offset, MCA))
261       MCA.getContext().reportFatalError(
262           LocalOffset->getLoc(), ".localentry expression must be absolute.");
263 
264     switch (Offset) {
265     default:
266       MCA.getContext().reportFatalError(
267           LocalOffset->getLoc(),
268           ".localentry expression is not a valid power of 2.");
269     case 0:
270       return 0;
271     case 1:
272       return 1 << ELF::STO_PPC64_LOCAL_BIT;
273     case 4:
274     case 8:
275     case 16:
276     case 32:
277     case 64:
278       return (int)Log2(Offset) << (int)ELF::STO_PPC64_LOCAL_BIT;
279     }
280   }
281 };
282 
283 class PPCTargetMachOStreamer : public PPCTargetStreamer {
284 public:
285   PPCTargetMachOStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
286 
287   void emitTCEntry(const MCSymbol &S,
288                    MCSymbolRefExpr::VariantKind Kind) override {
289     llvm_unreachable("Unknown pseudo-op: .tc");
290   }
291 
292   void emitMachine(StringRef CPU) override {
293     // FIXME: We should update the CPUType, CPUSubType in the Object file if
294     // the new values are different from the defaults.
295   }
296 
297   void emitAbiVersion(int AbiVersion) override {
298     llvm_unreachable("Unknown pseudo-op: .abiversion");
299   }
300 
301   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
302     llvm_unreachable("Unknown pseudo-op: .localentry");
303   }
304 };
305 
306 class PPCTargetXCOFFStreamer : public PPCTargetStreamer {
307 public:
308   PPCTargetXCOFFStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
309 
310   void emitTCEntry(const MCSymbol &S,
311                    MCSymbolRefExpr::VariantKind Kind) override {
312     const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
313     const unsigned PointerSize = MAI->getCodePointerSize();
314     Streamer.emitValueToAlignment(PointerSize);
315     Streamer.emitSymbolValue(&S, PointerSize);
316   }
317 
318   void emitMachine(StringRef CPU) override {
319     llvm_unreachable("Machine pseudo-ops are invalid for XCOFF.");
320   }
321 
322   void emitAbiVersion(int AbiVersion) override {
323     llvm_unreachable("ABI-version pseudo-ops are invalid for XCOFF.");
324   }
325 
326   void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
327     llvm_unreachable("Local-entry pseudo-ops are invalid for XCOFF.");
328   }
329 };
330 
331 } // end anonymous namespace
332 
333 static MCTargetStreamer *createAsmTargetStreamer(MCStreamer &S,
334                                                  formatted_raw_ostream &OS,
335                                                  MCInstPrinter *InstPrint,
336                                                  bool isVerboseAsm) {
337   return new PPCTargetAsmStreamer(S, OS);
338 }
339 
340 static MCTargetStreamer *
341 createObjectTargetStreamer(MCStreamer &S, const MCSubtargetInfo &STI) {
342   const Triple &TT = STI.getTargetTriple();
343   if (TT.isOSBinFormatELF())
344     return new PPCTargetELFStreamer(S);
345   if (TT.isOSBinFormatXCOFF())
346     return new PPCTargetXCOFFStreamer(S);
347   return new PPCTargetMachOStreamer(S);
348 }
349 
350 static MCInstPrinter *createPPCMCInstPrinter(const Triple &T,
351                                              unsigned SyntaxVariant,
352                                              const MCAsmInfo &MAI,
353                                              const MCInstrInfo &MII,
354                                              const MCRegisterInfo &MRI) {
355   return new PPCInstPrinter(MAI, MII, MRI, T);
356 }
357 
358 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializePowerPCTargetMC() {
359   for (Target *T : {&getThePPC32Target(), &getThePPC32LETarget(),
360                     &getThePPC64Target(), &getThePPC64LETarget()}) {
361     // Register the MC asm info.
362     RegisterMCAsmInfoFn C(*T, createPPCMCAsmInfo);
363 
364     // Register the MC instruction info.
365     TargetRegistry::RegisterMCInstrInfo(*T, createPPCMCInstrInfo);
366 
367     // Register the MC register info.
368     TargetRegistry::RegisterMCRegInfo(*T, createPPCMCRegisterInfo);
369 
370     // Register the MC subtarget info.
371     TargetRegistry::RegisterMCSubtargetInfo(*T, createPPCMCSubtargetInfo);
372 
373     // Register the MC Code Emitter
374     TargetRegistry::RegisterMCCodeEmitter(*T, createPPCMCCodeEmitter);
375 
376     // Register the asm backend.
377     TargetRegistry::RegisterMCAsmBackend(*T, createPPCAsmBackend);
378 
379     // Register the elf streamer.
380     TargetRegistry::RegisterELFStreamer(*T, createPPCMCStreamer);
381 
382     // Register the object target streamer.
383     TargetRegistry::RegisterObjectTargetStreamer(*T,
384                                                  createObjectTargetStreamer);
385 
386     // Register the asm target streamer.
387     TargetRegistry::RegisterAsmTargetStreamer(*T, createAsmTargetStreamer);
388 
389     // Register the MCInstPrinter.
390     TargetRegistry::RegisterMCInstPrinter(*T, createPPCMCInstPrinter);
391   }
392 }
393