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