1 //===- AArch64AsmPrinter.cpp - AArch64 LLVM assembly writer ---------------===//
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 contains a printer that converts from our internal representation
11 // of machine-dependent LLVM code to the AArch64 assembly language.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "AArch64.h"
16 #include "AArch64MCInstLower.h"
17 #include "AArch64MachineFunctionInfo.h"
18 #include "AArch64RegisterInfo.h"
19 #include "AArch64Subtarget.h"
20 #include "AArch64TargetObjectFile.h"
21 #include "InstPrinter/AArch64InstPrinter.h"
22 #include "MCTargetDesc/AArch64AddressingModes.h"
23 #include "MCTargetDesc/AArch64MCTargetDesc.h"
24 #include "Utils/AArch64BaseInfo.h"
25 #include "llvm/ADT/SmallString.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/ADT/Twine.h"
30 #include "llvm/CodeGen/AsmPrinter.h"
31 #include "llvm/CodeGen/MachineBasicBlock.h"
32 #include "llvm/CodeGen/MachineFunction.h"
33 #include "llvm/CodeGen/MachineInstr.h"
34 #include "llvm/CodeGen/MachineOperand.h"
35 #include "llvm/CodeGen/StackMaps.h"
36 #include "llvm/CodeGen/TargetRegisterInfo.h"
37 #include "llvm/IR/DataLayout.h"
38 #include "llvm/IR/DebugInfoMetadata.h"
39 #include "llvm/MC/MCAsmInfo.h"
40 #include "llvm/MC/MCContext.h"
41 #include "llvm/MC/MCInst.h"
42 #include "llvm/MC/MCInstBuilder.h"
43 #include "llvm/MC/MCStreamer.h"
44 #include "llvm/MC/MCSymbol.h"
45 #include "llvm/Support/Casting.h"
46 #include "llvm/Support/ErrorHandling.h"
47 #include "llvm/Support/TargetRegistry.h"
48 #include "llvm/Support/raw_ostream.h"
49 #include "llvm/Target/TargetMachine.h"
50 #include <algorithm>
51 #include <cassert>
52 #include <cstdint>
53 #include <map>
54 #include <memory>
55 
56 using namespace llvm;
57 
58 #define DEBUG_TYPE "asm-printer"
59 
60 namespace {
61 
62 class AArch64AsmPrinter : public AsmPrinter {
63   AArch64MCInstLower MCInstLowering;
64   StackMaps SM;
65   const AArch64Subtarget *STI;
66 
67 public:
68   AArch64AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
69       : AsmPrinter(TM, std::move(Streamer)), MCInstLowering(OutContext, *this),
70         SM(*this) {}
71 
72   StringRef getPassName() const override { return "AArch64 Assembly Printer"; }
73 
74   /// \brief Wrapper for MCInstLowering.lowerOperand() for the
75   /// tblgen'erated pseudo lowering.
76   bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp) const {
77     return MCInstLowering.lowerOperand(MO, MCOp);
78   }
79 
80   void LowerSTACKMAP(MCStreamer &OutStreamer, StackMaps &SM,
81                      const MachineInstr &MI);
82   void LowerPATCHPOINT(MCStreamer &OutStreamer, StackMaps &SM,
83                        const MachineInstr &MI);
84 
85   void LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI);
86   void LowerPATCHABLE_FUNCTION_EXIT(const MachineInstr &MI);
87   void LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI);
88 
89   void EmitSled(const MachineInstr &MI, SledKind Kind);
90 
91   /// \brief tblgen'erated driver function for lowering simple MI->MC
92   /// pseudo instructions.
93   bool emitPseudoExpansionLowering(MCStreamer &OutStreamer,
94                                    const MachineInstr *MI);
95 
96   void EmitInstruction(const MachineInstr *MI) override;
97 
98   void getAnalysisUsage(AnalysisUsage &AU) const override {
99     AsmPrinter::getAnalysisUsage(AU);
100     AU.setPreservesAll();
101   }
102 
103   bool runOnMachineFunction(MachineFunction &F) override {
104     AArch64FI = F.getInfo<AArch64FunctionInfo>();
105     STI = static_cast<const AArch64Subtarget*>(&F.getSubtarget());
106     bool Result = AsmPrinter::runOnMachineFunction(F);
107     emitXRayTable();
108     return Result;
109   }
110 
111 private:
112   void printOperand(const MachineInstr *MI, unsigned OpNum, raw_ostream &O);
113   bool printAsmMRegister(const MachineOperand &MO, char Mode, raw_ostream &O);
114   bool printAsmRegInClass(const MachineOperand &MO,
115                           const TargetRegisterClass *RC, bool isVector,
116                           raw_ostream &O);
117 
118   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
119                        unsigned AsmVariant, const char *ExtraCode,
120                        raw_ostream &O) override;
121   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
122                              unsigned AsmVariant, const char *ExtraCode,
123                              raw_ostream &O) override;
124 
125   void PrintDebugValueComment(const MachineInstr *MI, raw_ostream &OS);
126 
127   void EmitFunctionBodyEnd() override;
128 
129   MCSymbol *GetCPISymbol(unsigned CPID) const override;
130   void EmitEndOfAsmFile(Module &M) override;
131 
132   AArch64FunctionInfo *AArch64FI = nullptr;
133 
134   /// \brief Emit the LOHs contained in AArch64FI.
135   void EmitLOHs();
136 
137   /// Emit instruction to set float register to zero.
138   void EmitFMov0(const MachineInstr &MI);
139 
140   using MInstToMCSymbol = std::map<const MachineInstr *, MCSymbol *>;
141 
142   MInstToMCSymbol LOHInstToLabel;
143 };
144 
145 } // end anonymous namespace
146 
147 void AArch64AsmPrinter::LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI)
148 {
149   EmitSled(MI, SledKind::FUNCTION_ENTER);
150 }
151 
152 void AArch64AsmPrinter::LowerPATCHABLE_FUNCTION_EXIT(const MachineInstr &MI)
153 {
154   EmitSled(MI, SledKind::FUNCTION_EXIT);
155 }
156 
157 void AArch64AsmPrinter::LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI)
158 {
159   EmitSled(MI, SledKind::TAIL_CALL);
160 }
161 
162 void AArch64AsmPrinter::EmitSled(const MachineInstr &MI, SledKind Kind)
163 {
164   static const int8_t NoopsInSledCount = 7;
165   // We want to emit the following pattern:
166   //
167   // .Lxray_sled_N:
168   //   ALIGN
169   //   B #32
170   //   ; 7 NOP instructions (28 bytes)
171   // .tmpN
172   //
173   // We need the 28 bytes (7 instructions) because at runtime, we'd be patching
174   // over the full 32 bytes (8 instructions) with the following pattern:
175   //
176   //   STP X0, X30, [SP, #-16]! ; push X0 and the link register to the stack
177   //   LDR W0, #12 ; W0 := function ID
178   //   LDR X16,#12 ; X16 := addr of __xray_FunctionEntry or __xray_FunctionExit
179   //   BLR X16 ; call the tracing trampoline
180   //   ;DATA: 32 bits of function ID
181   //   ;DATA: lower 32 bits of the address of the trampoline
182   //   ;DATA: higher 32 bits of the address of the trampoline
183   //   LDP X0, X30, [SP], #16 ; pop X0 and the link register from the stack
184   //
185   OutStreamer->EmitCodeAlignment(4);
186   auto CurSled = OutContext.createTempSymbol("xray_sled_", true);
187   OutStreamer->EmitLabel(CurSled);
188   auto Target = OutContext.createTempSymbol();
189 
190   // Emit "B #32" instruction, which jumps over the next 28 bytes.
191   // The operand has to be the number of 4-byte instructions to jump over,
192   // including the current instruction.
193   EmitToStreamer(*OutStreamer, MCInstBuilder(AArch64::B).addImm(8));
194 
195   for (int8_t I = 0; I < NoopsInSledCount; I++)
196     EmitToStreamer(*OutStreamer, MCInstBuilder(AArch64::HINT).addImm(0));
197 
198   OutStreamer->EmitLabel(Target);
199   recordSled(CurSled, MI, Kind);
200 }
201 
202 void AArch64AsmPrinter::EmitEndOfAsmFile(Module &M) {
203   const Triple &TT = TM.getTargetTriple();
204   if (TT.isOSBinFormatMachO()) {
205     // Funny Darwin hack: This flag tells the linker that no global symbols
206     // contain code that falls through to other global symbols (e.g. the obvious
207     // implementation of multiple entry points).  If this doesn't occur, the
208     // linker can safely perform dead code stripping.  Since LLVM never
209     // generates code that does this, it is always safe to set.
210     OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
211     SM.serializeToStackMapSection();
212   }
213 }
214 
215 void AArch64AsmPrinter::EmitLOHs() {
216   SmallVector<MCSymbol *, 3> MCArgs;
217 
218   for (const auto &D : AArch64FI->getLOHContainer()) {
219     for (const MachineInstr *MI : D.getArgs()) {
220       MInstToMCSymbol::iterator LabelIt = LOHInstToLabel.find(MI);
221       assert(LabelIt != LOHInstToLabel.end() &&
222              "Label hasn't been inserted for LOH related instruction");
223       MCArgs.push_back(LabelIt->second);
224     }
225     OutStreamer->EmitLOHDirective(D.getKind(), MCArgs);
226     MCArgs.clear();
227   }
228 }
229 
230 void AArch64AsmPrinter::EmitFunctionBodyEnd() {
231   if (!AArch64FI->getLOHRelated().empty())
232     EmitLOHs();
233 }
234 
235 /// GetCPISymbol - Return the symbol for the specified constant pool entry.
236 MCSymbol *AArch64AsmPrinter::GetCPISymbol(unsigned CPID) const {
237   // Darwin uses a linker-private symbol name for constant-pools (to
238   // avoid addends on the relocation?), ELF has no such concept and
239   // uses a normal private symbol.
240   if (!getDataLayout().getLinkerPrivateGlobalPrefix().empty())
241     return OutContext.getOrCreateSymbol(
242         Twine(getDataLayout().getLinkerPrivateGlobalPrefix()) + "CPI" +
243         Twine(getFunctionNumber()) + "_" + Twine(CPID));
244 
245   return OutContext.getOrCreateSymbol(
246       Twine(getDataLayout().getPrivateGlobalPrefix()) + "CPI" +
247       Twine(getFunctionNumber()) + "_" + Twine(CPID));
248 }
249 
250 void AArch64AsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNum,
251                                      raw_ostream &O) {
252   const MachineOperand &MO = MI->getOperand(OpNum);
253   switch (MO.getType()) {
254   default:
255     llvm_unreachable("<unknown operand type>");
256   case MachineOperand::MO_Register: {
257     unsigned Reg = MO.getReg();
258     assert(TargetRegisterInfo::isPhysicalRegister(Reg));
259     assert(!MO.getSubReg() && "Subregs should be eliminated!");
260     O << AArch64InstPrinter::getRegisterName(Reg);
261     break;
262   }
263   case MachineOperand::MO_Immediate: {
264     int64_t Imm = MO.getImm();
265     O << '#' << Imm;
266     break;
267   }
268   case MachineOperand::MO_GlobalAddress: {
269     const GlobalValue *GV = MO.getGlobal();
270     MCSymbol *Sym = getSymbol(GV);
271 
272     // FIXME: Can we get anything other than a plain symbol here?
273     assert(!MO.getTargetFlags() && "Unknown operand target flag!");
274 
275     Sym->print(O, MAI);
276     printOffset(MO.getOffset(), O);
277     break;
278   }
279   }
280 }
281 
282 bool AArch64AsmPrinter::printAsmMRegister(const MachineOperand &MO, char Mode,
283                                           raw_ostream &O) {
284   unsigned Reg = MO.getReg();
285   switch (Mode) {
286   default:
287     return true; // Unknown mode.
288   case 'w':
289     Reg = getWRegFromXReg(Reg);
290     break;
291   case 'x':
292     Reg = getXRegFromWReg(Reg);
293     break;
294   }
295 
296   O << AArch64InstPrinter::getRegisterName(Reg);
297   return false;
298 }
299 
300 // Prints the register in MO using class RC using the offset in the
301 // new register class. This should not be used for cross class
302 // printing.
303 bool AArch64AsmPrinter::printAsmRegInClass(const MachineOperand &MO,
304                                            const TargetRegisterClass *RC,
305                                            bool isVector, raw_ostream &O) {
306   assert(MO.isReg() && "Should only get here with a register!");
307   const TargetRegisterInfo *RI = STI->getRegisterInfo();
308   unsigned Reg = MO.getReg();
309   unsigned RegToPrint = RC->getRegister(RI->getEncodingValue(Reg));
310   assert(RI->regsOverlap(RegToPrint, Reg));
311   O << AArch64InstPrinter::getRegisterName(
312            RegToPrint, isVector ? AArch64::vreg : AArch64::NoRegAltName);
313   return false;
314 }
315 
316 bool AArch64AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
317                                         unsigned AsmVariant,
318                                         const char *ExtraCode, raw_ostream &O) {
319   const MachineOperand &MO = MI->getOperand(OpNum);
320 
321   // First try the generic code, which knows about modifiers like 'c' and 'n'.
322   if (!AsmPrinter::PrintAsmOperand(MI, OpNum, AsmVariant, ExtraCode, O))
323     return false;
324 
325   // Does this asm operand have a single letter operand modifier?
326   if (ExtraCode && ExtraCode[0]) {
327     if (ExtraCode[1] != 0)
328       return true; // Unknown modifier.
329 
330     switch (ExtraCode[0]) {
331     default:
332       return true; // Unknown modifier.
333     case 'a':      // Print 'a' modifier
334       PrintAsmMemoryOperand(MI, OpNum, AsmVariant, ExtraCode, O);
335       return false;
336     case 'w':      // Print W register
337     case 'x':      // Print X register
338       if (MO.isReg())
339         return printAsmMRegister(MO, ExtraCode[0], O);
340       if (MO.isImm() && MO.getImm() == 0) {
341         unsigned Reg = ExtraCode[0] == 'w' ? AArch64::WZR : AArch64::XZR;
342         O << AArch64InstPrinter::getRegisterName(Reg);
343         return false;
344       }
345       printOperand(MI, OpNum, O);
346       return false;
347     case 'b': // Print B register.
348     case 'h': // Print H register.
349     case 's': // Print S register.
350     case 'd': // Print D register.
351     case 'q': // Print Q register.
352       if (MO.isReg()) {
353         const TargetRegisterClass *RC;
354         switch (ExtraCode[0]) {
355         case 'b':
356           RC = &AArch64::FPR8RegClass;
357           break;
358         case 'h':
359           RC = &AArch64::FPR16RegClass;
360           break;
361         case 's':
362           RC = &AArch64::FPR32RegClass;
363           break;
364         case 'd':
365           RC = &AArch64::FPR64RegClass;
366           break;
367         case 'q':
368           RC = &AArch64::FPR128RegClass;
369           break;
370         default:
371           return true;
372         }
373         return printAsmRegInClass(MO, RC, false /* vector */, O);
374       }
375       printOperand(MI, OpNum, O);
376       return false;
377     }
378   }
379 
380   // According to ARM, we should emit x and v registers unless we have a
381   // modifier.
382   if (MO.isReg()) {
383     unsigned Reg = MO.getReg();
384 
385     // If this is a w or x register, print an x register.
386     if (AArch64::GPR32allRegClass.contains(Reg) ||
387         AArch64::GPR64allRegClass.contains(Reg))
388       return printAsmMRegister(MO, 'x', O);
389 
390     // If this is a b, h, s, d, or q register, print it as a v register.
391     return printAsmRegInClass(MO, &AArch64::FPR128RegClass, true /* vector */,
392                               O);
393   }
394 
395   printOperand(MI, OpNum, O);
396   return false;
397 }
398 
399 bool AArch64AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
400                                               unsigned OpNum,
401                                               unsigned AsmVariant,
402                                               const char *ExtraCode,
403                                               raw_ostream &O) {
404   if (ExtraCode && ExtraCode[0] && ExtraCode[0] != 'a')
405     return true; // Unknown modifier.
406 
407   const MachineOperand &MO = MI->getOperand(OpNum);
408   assert(MO.isReg() && "unexpected inline asm memory operand");
409   O << "[" << AArch64InstPrinter::getRegisterName(MO.getReg()) << "]";
410   return false;
411 }
412 
413 void AArch64AsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
414                                                raw_ostream &OS) {
415   unsigned NOps = MI->getNumOperands();
416   assert(NOps == 4);
417   OS << '\t' << MAI->getCommentString() << "DEBUG_VALUE: ";
418   // cast away const; DIetc do not take const operands for some reason.
419   OS << cast<DILocalVariable>(MI->getOperand(NOps - 2).getMetadata())
420             ->getName();
421   OS << " <- ";
422   // Frame address.  Currently handles register +- offset only.
423   assert(MI->getOperand(0).isReg() && MI->getOperand(1).isImm());
424   OS << '[';
425   printOperand(MI, 0, OS);
426   OS << '+';
427   printOperand(MI, 1, OS);
428   OS << ']';
429   OS << "+";
430   printOperand(MI, NOps - 2, OS);
431 }
432 
433 void AArch64AsmPrinter::LowerSTACKMAP(MCStreamer &OutStreamer, StackMaps &SM,
434                                       const MachineInstr &MI) {
435   unsigned NumNOPBytes = StackMapOpers(&MI).getNumPatchBytes();
436 
437   SM.recordStackMap(MI);
438   assert(NumNOPBytes % 4 == 0 && "Invalid number of NOP bytes requested!");
439 
440   // Scan ahead to trim the shadow.
441   const MachineBasicBlock &MBB = *MI.getParent();
442   MachineBasicBlock::const_iterator MII(MI);
443   ++MII;
444   while (NumNOPBytes > 0) {
445     if (MII == MBB.end() || MII->isCall() ||
446         MII->getOpcode() == AArch64::DBG_VALUE ||
447         MII->getOpcode() == TargetOpcode::PATCHPOINT ||
448         MII->getOpcode() == TargetOpcode::STACKMAP)
449       break;
450     ++MII;
451     NumNOPBytes -= 4;
452   }
453 
454   // Emit nops.
455   for (unsigned i = 0; i < NumNOPBytes; i += 4)
456     EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::HINT).addImm(0));
457 }
458 
459 // Lower a patchpoint of the form:
460 // [<def>], <id>, <numBytes>, <target>, <numArgs>
461 void AArch64AsmPrinter::LowerPATCHPOINT(MCStreamer &OutStreamer, StackMaps &SM,
462                                         const MachineInstr &MI) {
463   SM.recordPatchPoint(MI);
464 
465   PatchPointOpers Opers(&MI);
466 
467   int64_t CallTarget = Opers.getCallTarget().getImm();
468   unsigned EncodedBytes = 0;
469   if (CallTarget) {
470     assert((CallTarget & 0xFFFFFFFFFFFF) == CallTarget &&
471            "High 16 bits of call target should be zero.");
472     unsigned ScratchReg = MI.getOperand(Opers.getNextScratchIdx()).getReg();
473     EncodedBytes = 16;
474     // Materialize the jump address:
475     EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::MOVZXi)
476                                     .addReg(ScratchReg)
477                                     .addImm((CallTarget >> 32) & 0xFFFF)
478                                     .addImm(32));
479     EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::MOVKXi)
480                                     .addReg(ScratchReg)
481                                     .addReg(ScratchReg)
482                                     .addImm((CallTarget >> 16) & 0xFFFF)
483                                     .addImm(16));
484     EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::MOVKXi)
485                                     .addReg(ScratchReg)
486                                     .addReg(ScratchReg)
487                                     .addImm(CallTarget & 0xFFFF)
488                                     .addImm(0));
489     EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::BLR).addReg(ScratchReg));
490   }
491   // Emit padding.
492   unsigned NumBytes = Opers.getNumPatchBytes();
493   assert(NumBytes >= EncodedBytes &&
494          "Patchpoint can't request size less than the length of a call.");
495   assert((NumBytes - EncodedBytes) % 4 == 0 &&
496          "Invalid number of NOP bytes requested!");
497   for (unsigned i = EncodedBytes; i < NumBytes; i += 4)
498     EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::HINT).addImm(0));
499 }
500 
501 void AArch64AsmPrinter::EmitFMov0(const MachineInstr &MI) {
502   unsigned DestReg = MI.getOperand(0).getReg();
503   if (STI->hasZeroCycleZeroing() && !STI->hasZeroCycleZeroingFPWorkaround()) {
504     // Convert H/S/D register to corresponding Q register
505     if (AArch64::H0 <= DestReg && DestReg <= AArch64::H31)
506       DestReg = AArch64::Q0 + (DestReg - AArch64::H0);
507     else if (AArch64::S0 <= DestReg && DestReg <= AArch64::S31)
508       DestReg = AArch64::Q0 + (DestReg - AArch64::S0);
509     else {
510       assert(AArch64::D0 <= DestReg && DestReg <= AArch64::D31);
511       DestReg = AArch64::Q0 + (DestReg - AArch64::D0);
512     }
513     MCInst MOVI;
514     MOVI.setOpcode(AArch64::MOVIv2d_ns);
515     MOVI.addOperand(MCOperand::createReg(DestReg));
516     MOVI.addOperand(MCOperand::createImm(0));
517     EmitToStreamer(*OutStreamer, MOVI);
518   } else {
519     MCInst FMov;
520     switch (MI.getOpcode()) {
521     default: llvm_unreachable("Unexpected opcode");
522     case AArch64::FMOVH0:
523       FMov.setOpcode(AArch64::FMOVWHr);
524       FMov.addOperand(MCOperand::createReg(DestReg));
525       FMov.addOperand(MCOperand::createReg(AArch64::WZR));
526       break;
527     case AArch64::FMOVS0:
528       FMov.setOpcode(AArch64::FMOVWSr);
529       FMov.addOperand(MCOperand::createReg(DestReg));
530       FMov.addOperand(MCOperand::createReg(AArch64::WZR));
531       break;
532     case AArch64::FMOVD0:
533       FMov.setOpcode(AArch64::FMOVXDr);
534       FMov.addOperand(MCOperand::createReg(DestReg));
535       FMov.addOperand(MCOperand::createReg(AArch64::XZR));
536       break;
537     }
538     EmitToStreamer(*OutStreamer, FMov);
539   }
540 }
541 
542 // Simple pseudo-instructions have their lowering (with expansion to real
543 // instructions) auto-generated.
544 #include "AArch64GenMCPseudoLowering.inc"
545 
546 void AArch64AsmPrinter::EmitInstruction(const MachineInstr *MI) {
547   // Do any auto-generated pseudo lowerings.
548   if (emitPseudoExpansionLowering(*OutStreamer, MI))
549     return;
550 
551   if (AArch64FI->getLOHRelated().count(MI)) {
552     // Generate a label for LOH related instruction
553     MCSymbol *LOHLabel = createTempSymbol("loh");
554     // Associate the instruction with the label
555     LOHInstToLabel[MI] = LOHLabel;
556     OutStreamer->EmitLabel(LOHLabel);
557   }
558 
559   // Do any manual lowerings.
560   switch (MI->getOpcode()) {
561   default:
562     break;
563   case AArch64::MOVIv2d_ns:
564     // If the target has <rdar://problem/16473581>, lower this
565     // instruction to movi.16b instead.
566     if (STI->hasZeroCycleZeroingFPWorkaround() &&
567         MI->getOperand(1).getImm() == 0) {
568       MCInst TmpInst;
569       TmpInst.setOpcode(AArch64::MOVIv16b_ns);
570       TmpInst.addOperand(MCOperand::createReg(MI->getOperand(0).getReg()));
571       TmpInst.addOperand(MCOperand::createImm(MI->getOperand(1).getImm()));
572       EmitToStreamer(*OutStreamer, TmpInst);
573       return;
574     }
575     break;
576 
577   case AArch64::DBG_VALUE: {
578     if (isVerbose() && OutStreamer->hasRawTextSupport()) {
579       SmallString<128> TmpStr;
580       raw_svector_ostream OS(TmpStr);
581       PrintDebugValueComment(MI, OS);
582       OutStreamer->EmitRawText(StringRef(OS.str()));
583     }
584     return;
585   }
586 
587   // Tail calls use pseudo instructions so they have the proper code-gen
588   // attributes (isCall, isReturn, etc.). We lower them to the real
589   // instruction here.
590   case AArch64::TCRETURNri: {
591     MCInst TmpInst;
592     TmpInst.setOpcode(AArch64::BR);
593     TmpInst.addOperand(MCOperand::createReg(MI->getOperand(0).getReg()));
594     EmitToStreamer(*OutStreamer, TmpInst);
595     return;
596   }
597   case AArch64::TCRETURNdi: {
598     MCOperand Dest;
599     MCInstLowering.lowerOperand(MI->getOperand(0), Dest);
600     MCInst TmpInst;
601     TmpInst.setOpcode(AArch64::B);
602     TmpInst.addOperand(Dest);
603     EmitToStreamer(*OutStreamer, TmpInst);
604     return;
605   }
606   case AArch64::TLSDESC_CALLSEQ: {
607     /// lower this to:
608     ///    adrp  x0, :tlsdesc:var
609     ///    ldr   x1, [x0, #:tlsdesc_lo12:var]
610     ///    add   x0, x0, #:tlsdesc_lo12:var
611     ///    .tlsdesccall var
612     ///    blr   x1
613     ///    (TPIDR_EL0 offset now in x0)
614     const MachineOperand &MO_Sym = MI->getOperand(0);
615     MachineOperand MO_TLSDESC_LO12(MO_Sym), MO_TLSDESC(MO_Sym);
616     MCOperand Sym, SymTLSDescLo12, SymTLSDesc;
617     MO_TLSDESC_LO12.setTargetFlags(AArch64II::MO_TLS | AArch64II::MO_PAGEOFF);
618     MO_TLSDESC.setTargetFlags(AArch64II::MO_TLS | AArch64II::MO_PAGE);
619     MCInstLowering.lowerOperand(MO_Sym, Sym);
620     MCInstLowering.lowerOperand(MO_TLSDESC_LO12, SymTLSDescLo12);
621     MCInstLowering.lowerOperand(MO_TLSDESC, SymTLSDesc);
622 
623     MCInst Adrp;
624     Adrp.setOpcode(AArch64::ADRP);
625     Adrp.addOperand(MCOperand::createReg(AArch64::X0));
626     Adrp.addOperand(SymTLSDesc);
627     EmitToStreamer(*OutStreamer, Adrp);
628 
629     MCInst Ldr;
630     Ldr.setOpcode(AArch64::LDRXui);
631     Ldr.addOperand(MCOperand::createReg(AArch64::X1));
632     Ldr.addOperand(MCOperand::createReg(AArch64::X0));
633     Ldr.addOperand(SymTLSDescLo12);
634     Ldr.addOperand(MCOperand::createImm(0));
635     EmitToStreamer(*OutStreamer, Ldr);
636 
637     MCInst Add;
638     Add.setOpcode(AArch64::ADDXri);
639     Add.addOperand(MCOperand::createReg(AArch64::X0));
640     Add.addOperand(MCOperand::createReg(AArch64::X0));
641     Add.addOperand(SymTLSDescLo12);
642     Add.addOperand(MCOperand::createImm(AArch64_AM::getShiftValue(0)));
643     EmitToStreamer(*OutStreamer, Add);
644 
645     // Emit a relocation-annotation. This expands to no code, but requests
646     // the following instruction gets an R_AARCH64_TLSDESC_CALL.
647     MCInst TLSDescCall;
648     TLSDescCall.setOpcode(AArch64::TLSDESCCALL);
649     TLSDescCall.addOperand(Sym);
650     EmitToStreamer(*OutStreamer, TLSDescCall);
651 
652     MCInst Blr;
653     Blr.setOpcode(AArch64::BLR);
654     Blr.addOperand(MCOperand::createReg(AArch64::X1));
655     EmitToStreamer(*OutStreamer, Blr);
656 
657     return;
658   }
659 
660   case AArch64::FMOVH0:
661   case AArch64::FMOVS0:
662   case AArch64::FMOVD0:
663     EmitFMov0(*MI);
664     return;
665 
666   case TargetOpcode::STACKMAP:
667     return LowerSTACKMAP(*OutStreamer, SM, *MI);
668 
669   case TargetOpcode::PATCHPOINT:
670     return LowerPATCHPOINT(*OutStreamer, SM, *MI);
671 
672   case TargetOpcode::PATCHABLE_FUNCTION_ENTER:
673     LowerPATCHABLE_FUNCTION_ENTER(*MI);
674     return;
675 
676   case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
677     LowerPATCHABLE_FUNCTION_EXIT(*MI);
678     return;
679 
680   case TargetOpcode::PATCHABLE_TAIL_CALL:
681     LowerPATCHABLE_TAIL_CALL(*MI);
682     return;
683   }
684 
685   // Finally, do the automated lowerings for everything else.
686   MCInst TmpInst;
687   MCInstLowering.Lower(MI, TmpInst);
688   EmitToStreamer(*OutStreamer, TmpInst);
689 }
690 
691 // Force static initialization.
692 extern "C" void LLVMInitializeAArch64AsmPrinter() {
693   RegisterAsmPrinter<AArch64AsmPrinter> X(getTheAArch64leTarget());
694   RegisterAsmPrinter<AArch64AsmPrinter> Y(getTheAArch64beTarget());
695   RegisterAsmPrinter<AArch64AsmPrinter> Z(getTheARM64Target());
696 }
697