xref: /freebsd/contrib/llvm-project/llvm/lib/Target/X86/X86AsmPrinter.cpp (revision 92b14858b44dc4b3b57154a10e9de1b39d791e41) 
1 //===-- X86AsmPrinter.cpp - Convert X86 LLVM code to AT&T assembly --------===//
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 contains a printer that converts from our internal representation
10 // of machine-dependent LLVM code to X86 machine code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "X86AsmPrinter.h"
15 #include "MCTargetDesc/X86ATTInstPrinter.h"
16 #include "MCTargetDesc/X86BaseInfo.h"
17 #include "MCTargetDesc/X86TargetStreamer.h"
18 #include "TargetInfo/X86TargetInfo.h"
19 #include "X86InstrInfo.h"
20 #include "X86MachineFunctionInfo.h"
21 #include "llvm/BinaryFormat/COFF.h"
22 #include "llvm/BinaryFormat/ELF.h"
23 #include "llvm/CodeGen/MachineConstantPool.h"
24 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
25 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/InlineAsm.h"
28 #include "llvm/IR/Mangler.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/IR/Type.h"
31 #include "llvm/MC/MCCodeEmitter.h"
32 #include "llvm/MC/MCContext.h"
33 #include "llvm/MC/MCExpr.h"
34 #include "llvm/MC/MCSectionCOFF.h"
35 #include "llvm/MC/MCSectionELF.h"
36 #include "llvm/MC/MCSectionMachO.h"
37 #include "llvm/MC/MCStreamer.h"
38 #include "llvm/MC/MCSymbol.h"
39 #include "llvm/Support/Debug.h"
40 #include "llvm/Support/ErrorHandling.h"
41 #include "llvm/Support/MachineValueType.h"
42 #include "llvm/Support/TargetRegistry.h"
43 using namespace llvm;
44 
45 X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
46                              std::unique_ptr<MCStreamer> Streamer)
47     : AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this) {}
48 
49 //===----------------------------------------------------------------------===//
50 // Primitive Helper Functions.
51 //===----------------------------------------------------------------------===//
52 
53 /// runOnMachineFunction - Emit the function body.
54 ///
55 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
56   Subtarget = &MF.getSubtarget<X86Subtarget>();
57 
58   SMShadowTracker.startFunction(MF);
59   CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
60       *Subtarget->getInstrInfo(), *Subtarget->getRegisterInfo(),
61       MF.getContext()));
62 
63   EmitFPOData =
64       Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
65 
66   SetupMachineFunction(MF);
67 
68   if (Subtarget->isTargetCOFF()) {
69     bool Local = MF.getFunction().hasLocalLinkage();
70     OutStreamer->BeginCOFFSymbolDef(CurrentFnSym);
71     OutStreamer->EmitCOFFSymbolStorageClass(
72         Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
73     OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
74                                                << COFF::SCT_COMPLEX_TYPE_SHIFT);
75     OutStreamer->EndCOFFSymbolDef();
76   }
77 
78   // Emit the rest of the function body.
79   EmitFunctionBody();
80 
81   // Emit the XRay table for this function.
82   emitXRayTable();
83 
84   EmitFPOData = false;
85 
86   // We didn't modify anything.
87   return false;
88 }
89 
90 void X86AsmPrinter::EmitFunctionBodyStart() {
91   if (EmitFPOData) {
92     if (auto *XTS =
93         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
94       XTS->emitFPOProc(
95           CurrentFnSym,
96           MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
97   }
98 }
99 
100 void X86AsmPrinter::EmitFunctionBodyEnd() {
101   if (EmitFPOData) {
102     if (auto *XTS =
103             static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
104       XTS->emitFPOEndProc();
105   }
106 }
107 
108 /// PrintSymbolOperand - Print a raw symbol reference operand.  This handles
109 /// jump tables, constant pools, global address and external symbols, all of
110 /// which print to a label with various suffixes for relocation types etc.
111 void X86AsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
112                                        raw_ostream &O) {
113   switch (MO.getType()) {
114   default: llvm_unreachable("unknown symbol type!");
115   case MachineOperand::MO_ConstantPoolIndex:
116     GetCPISymbol(MO.getIndex())->print(O, MAI);
117     printOffset(MO.getOffset(), O);
118     break;
119   case MachineOperand::MO_GlobalAddress: {
120     const GlobalValue *GV = MO.getGlobal();
121 
122     MCSymbol *GVSym;
123     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
124         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
125       GVSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
126     else
127       GVSym = getSymbol(GV);
128 
129     // Handle dllimport linkage.
130     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
131       GVSym = OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
132     else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
133       GVSym =
134           OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
135 
136     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
137         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
138       MCSymbol *Sym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
139       MachineModuleInfoImpl::StubValueTy &StubSym =
140           MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
141       if (!StubSym.getPointer())
142         StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
143                                                      !GV->hasInternalLinkage());
144     }
145 
146     // If the name begins with a dollar-sign, enclose it in parens.  We do this
147     // to avoid having it look like an integer immediate to the assembler.
148     if (GVSym->getName()[0] != '$')
149       GVSym->print(O, MAI);
150     else {
151       O << '(';
152       GVSym->print(O, MAI);
153       O << ')';
154     }
155     printOffset(MO.getOffset(), O);
156     break;
157   }
158   }
159 
160   switch (MO.getTargetFlags()) {
161   default:
162     llvm_unreachable("Unknown target flag on GV operand");
163   case X86II::MO_NO_FLAG:    // No flag.
164     break;
165   case X86II::MO_DARWIN_NONLAZY:
166   case X86II::MO_DLLIMPORT:
167   case X86II::MO_COFFSTUB:
168     // These affect the name of the symbol, not any suffix.
169     break;
170   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
171     O << " + [.-";
172     MF->getPICBaseSymbol()->print(O, MAI);
173     O << ']';
174     break;
175   case X86II::MO_PIC_BASE_OFFSET:
176   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
177     O << '-';
178     MF->getPICBaseSymbol()->print(O, MAI);
179     break;
180   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
181   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
182   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
183   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
184   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
185   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
186   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
187   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
188   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
189   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
190   case X86II::MO_GOT:       O << "@GOT";       break;
191   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
192   case X86II::MO_PLT:       O << "@PLT";       break;
193   case X86II::MO_TLVP:      O << "@TLVP";      break;
194   case X86II::MO_TLVP_PIC_BASE:
195     O << "@TLVP" << '-';
196     MF->getPICBaseSymbol()->print(O, MAI);
197     break;
198   case X86II::MO_SECREL:    O << "@SECREL32";  break;
199   }
200 }
201 
202 void X86AsmPrinter::PrintOperand(const MachineInstr *MI, unsigned OpNo,
203                                  raw_ostream &O) {
204   const MachineOperand &MO = MI->getOperand(OpNo);
205   const bool IsATT = MI->getInlineAsmDialect() == InlineAsm::AD_ATT;
206   switch (MO.getType()) {
207   default: llvm_unreachable("unknown operand type!");
208   case MachineOperand::MO_Register: {
209     if (IsATT)
210       O << '%';
211     O << X86ATTInstPrinter::getRegisterName(MO.getReg());
212     return;
213   }
214 
215   case MachineOperand::MO_Immediate:
216     if (IsATT)
217       O << '$';
218     O << MO.getImm();
219     return;
220 
221   case MachineOperand::MO_ConstantPoolIndex:
222   case MachineOperand::MO_GlobalAddress: {
223     switch (MI->getInlineAsmDialect()) {
224     case InlineAsm::AD_ATT:
225       O << '$';
226       break;
227     case InlineAsm::AD_Intel:
228       O << "offset ";
229       break;
230     }
231     PrintSymbolOperand(MO, O);
232     break;
233   }
234   case MachineOperand::MO_BlockAddress: {
235     MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
236     Sym->print(O, MAI);
237     break;
238   }
239   }
240 }
241 
242 /// PrintModifiedOperand - Print subregisters based on supplied modifier,
243 /// deferring to PrintOperand() if no modifier was supplied or if operand is not
244 /// a register.
245 void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
246                                          raw_ostream &O, const char *Modifier) {
247   const MachineOperand &MO = MI->getOperand(OpNo);
248   if (!Modifier || MO.getType() != MachineOperand::MO_Register)
249     return PrintOperand(MI, OpNo, O);
250   if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
251     O << '%';
252   Register Reg = MO.getReg();
253   if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
254     unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
255         (strcmp(Modifier+6,"32") == 0) ? 32 :
256         (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
257     Reg = getX86SubSuperRegister(Reg, Size);
258   }
259   O << X86ATTInstPrinter::getRegisterName(Reg);
260 }
261 
262 /// PrintPCRelImm - This is used to print an immediate value that ends up
263 /// being encoded as a pc-relative value.  These print slightly differently, for
264 /// example, a $ is not emitted.
265 void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
266                                   raw_ostream &O) {
267   const MachineOperand &MO = MI->getOperand(OpNo);
268   switch (MO.getType()) {
269   default: llvm_unreachable("Unknown pcrel immediate operand");
270   case MachineOperand::MO_Register:
271     // pc-relativeness was handled when computing the value in the reg.
272     PrintOperand(MI, OpNo, O);
273     return;
274   case MachineOperand::MO_Immediate:
275     O << MO.getImm();
276     return;
277   case MachineOperand::MO_GlobalAddress:
278     PrintSymbolOperand(MO, O);
279     return;
280   }
281 }
282 
283 void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
284                                          raw_ostream &O, const char *Modifier) {
285   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
286   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
287   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
288 
289   // If we really don't want to print out (rip), don't.
290   bool HasBaseReg = BaseReg.getReg() != 0;
291   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
292       BaseReg.getReg() == X86::RIP)
293     HasBaseReg = false;
294 
295   // HasParenPart - True if we will print out the () part of the mem ref.
296   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
297 
298   switch (DispSpec.getType()) {
299   default:
300     llvm_unreachable("unknown operand type!");
301   case MachineOperand::MO_Immediate: {
302     int DispVal = DispSpec.getImm();
303     if (DispVal || !HasParenPart)
304       O << DispVal;
305     break;
306   }
307   case MachineOperand::MO_GlobalAddress:
308   case MachineOperand::MO_ConstantPoolIndex:
309     PrintSymbolOperand(DispSpec, O);
310     break;
311   }
312 
313   if (Modifier && strcmp(Modifier, "H") == 0)
314     O << "+8";
315 
316   if (HasParenPart) {
317     assert(IndexReg.getReg() != X86::ESP &&
318            "X86 doesn't allow scaling by ESP");
319 
320     O << '(';
321     if (HasBaseReg)
322       PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
323 
324     if (IndexReg.getReg()) {
325       O << ',';
326       PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
327       unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
328       if (ScaleVal != 1)
329         O << ',' << ScaleVal;
330     }
331     O << ')';
332   }
333 }
334 
335 void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
336                                       raw_ostream &O, const char *Modifier) {
337   assert(isMem(*MI, OpNo) && "Invalid memory reference!");
338   const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
339   if (Segment.getReg()) {
340     PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
341     O << ':';
342   }
343   PrintLeaMemReference(MI, OpNo, O, Modifier);
344 }
345 
346 
347 void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
348                                            unsigned OpNo, raw_ostream &O,
349                                            const char *Modifier) {
350   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
351   unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
352   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
353   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
354   const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
355 
356   // If we really don't want to print out (rip), don't.
357   bool HasBaseReg = BaseReg.getReg() != 0;
358   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
359       BaseReg.getReg() == X86::RIP)
360     HasBaseReg = false;
361 
362   // If this has a segment register, print it.
363   if (SegReg.getReg()) {
364     PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
365     O << ':';
366   }
367 
368   O << '[';
369 
370   bool NeedPlus = false;
371   if (HasBaseReg) {
372     PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
373     NeedPlus = true;
374   }
375 
376   if (IndexReg.getReg()) {
377     if (NeedPlus) O << " + ";
378     if (ScaleVal != 1)
379       O << ScaleVal << '*';
380     PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
381     NeedPlus = true;
382   }
383 
384   if (!DispSpec.isImm()) {
385     if (NeedPlus) O << " + ";
386     PrintOperand(MI, OpNo + X86::AddrDisp, O);
387   } else {
388     int64_t DispVal = DispSpec.getImm();
389     if (DispVal || (!IndexReg.getReg() && !HasBaseReg)) {
390       if (NeedPlus) {
391         if (DispVal > 0)
392           O << " + ";
393         else {
394           O << " - ";
395           DispVal = -DispVal;
396         }
397       }
398       O << DispVal;
399     }
400   }
401   O << ']';
402 }
403 
404 static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
405                               char Mode, raw_ostream &O) {
406   Register Reg = MO.getReg();
407   bool EmitPercent = true;
408 
409   if (!X86::GR8RegClass.contains(Reg) &&
410       !X86::GR16RegClass.contains(Reg) &&
411       !X86::GR32RegClass.contains(Reg) &&
412       !X86::GR64RegClass.contains(Reg))
413     return true;
414 
415   switch (Mode) {
416   default: return true;  // Unknown mode.
417   case 'b': // Print QImode register
418     Reg = getX86SubSuperRegister(Reg, 8);
419     break;
420   case 'h': // Print QImode high register
421     Reg = getX86SubSuperRegister(Reg, 8, true);
422     break;
423   case 'w': // Print HImode register
424     Reg = getX86SubSuperRegister(Reg, 16);
425     break;
426   case 'k': // Print SImode register
427     Reg = getX86SubSuperRegister(Reg, 32);
428     break;
429   case 'V':
430     EmitPercent = false;
431     LLVM_FALLTHROUGH;
432   case 'q':
433     // Print 64-bit register names if 64-bit integer registers are available.
434     // Otherwise, print 32-bit register names.
435     Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
436     break;
437   }
438 
439   if (EmitPercent)
440     O << '%';
441 
442   O << X86ATTInstPrinter::getRegisterName(Reg);
443   return false;
444 }
445 
446 /// PrintAsmOperand - Print out an operand for an inline asm expression.
447 ///
448 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
449                                     const char *ExtraCode, raw_ostream &O) {
450   // Does this asm operand have a single letter operand modifier?
451   if (ExtraCode && ExtraCode[0]) {
452     if (ExtraCode[1] != 0) return true; // Unknown modifier.
453 
454     const MachineOperand &MO = MI->getOperand(OpNo);
455 
456     switch (ExtraCode[0]) {
457     default:
458       // See if this is a generic print operand
459       return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
460     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
461       switch (MO.getType()) {
462       default:
463         return true;
464       case MachineOperand::MO_Immediate:
465         O << MO.getImm();
466         return false;
467       case MachineOperand::MO_ConstantPoolIndex:
468       case MachineOperand::MO_JumpTableIndex:
469       case MachineOperand::MO_ExternalSymbol:
470         llvm_unreachable("unexpected operand type!");
471       case MachineOperand::MO_GlobalAddress:
472         PrintSymbolOperand(MO, O);
473         if (Subtarget->isPICStyleRIPRel())
474           O << "(%rip)";
475         return false;
476       case MachineOperand::MO_Register:
477         O << '(';
478         PrintOperand(MI, OpNo, O);
479         O << ')';
480         return false;
481       }
482 
483     case 'c': // Don't print "$" before a global var name or constant.
484       switch (MO.getType()) {
485       default:
486         PrintOperand(MI, OpNo, O);
487         break;
488       case MachineOperand::MO_Immediate:
489         O << MO.getImm();
490         break;
491       case MachineOperand::MO_ConstantPoolIndex:
492       case MachineOperand::MO_JumpTableIndex:
493       case MachineOperand::MO_ExternalSymbol:
494         llvm_unreachable("unexpected operand type!");
495       case MachineOperand::MO_GlobalAddress:
496         PrintSymbolOperand(MO, O);
497         break;
498       }
499       return false;
500 
501     case 'A': // Print '*' before a register (it must be a register)
502       if (MO.isReg()) {
503         O << '*';
504         PrintOperand(MI, OpNo, O);
505         return false;
506       }
507       return true;
508 
509     case 'b': // Print QImode register
510     case 'h': // Print QImode high register
511     case 'w': // Print HImode register
512     case 'k': // Print SImode register
513     case 'q': // Print DImode register
514     case 'V': // Print native register without '%'
515       if (MO.isReg())
516         return printAsmMRegister(*this, MO, ExtraCode[0], O);
517       PrintOperand(MI, OpNo, O);
518       return false;
519 
520     case 'P': // This is the operand of a call, treat specially.
521       PrintPCRelImm(MI, OpNo, O);
522       return false;
523 
524     case 'n': // Negate the immediate or print a '-' before the operand.
525       // Note: this is a temporary solution. It should be handled target
526       // independently as part of the 'MC' work.
527       if (MO.isImm()) {
528         O << -MO.getImm();
529         return false;
530       }
531       O << '-';
532     }
533   }
534 
535   PrintOperand(MI, OpNo, O);
536   return false;
537 }
538 
539 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
540                                           const char *ExtraCode,
541                                           raw_ostream &O) {
542   if (ExtraCode && ExtraCode[0]) {
543     if (ExtraCode[1] != 0) return true; // Unknown modifier.
544 
545     switch (ExtraCode[0]) {
546     default: return true;  // Unknown modifier.
547     case 'b': // Print QImode register
548     case 'h': // Print QImode high register
549     case 'w': // Print HImode register
550     case 'k': // Print SImode register
551     case 'q': // Print SImode register
552       // These only apply to registers, ignore on mem.
553       break;
554     case 'H':
555       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
556         return true;  // Unsupported modifier in Intel inline assembly.
557       } else {
558         PrintMemReference(MI, OpNo, O, "H");
559       }
560       return false;
561     case 'P': // Don't print @PLT, but do print as memory.
562       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
563         PrintIntelMemReference(MI, OpNo, O, "no-rip");
564       } else {
565         PrintMemReference(MI, OpNo, O, "no-rip");
566       }
567       return false;
568     }
569   }
570   if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
571     PrintIntelMemReference(MI, OpNo, O, nullptr);
572   } else {
573     PrintMemReference(MI, OpNo, O, nullptr);
574   }
575   return false;
576 }
577 
578 void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
579   const Triple &TT = TM.getTargetTriple();
580 
581   if (TT.isOSBinFormatELF()) {
582     // Assemble feature flags that may require creation of a note section.
583     unsigned FeatureFlagsAnd = 0;
584     if (M.getModuleFlag("cf-protection-branch"))
585       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
586     if (M.getModuleFlag("cf-protection-return"))
587       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
588 
589     if (FeatureFlagsAnd) {
590       // Emit a .note.gnu.property section with the flags.
591       if (!TT.isArch32Bit() && !TT.isArch64Bit())
592         llvm_unreachable("CFProtection used on invalid architecture!");
593       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
594       MCSection *Nt = MMI->getContext().getELFSection(
595           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
596       OutStreamer->SwitchSection(Nt);
597 
598       // Emitting note header.
599       int WordSize = TT.isArch64Bit() ? 8 : 4;
600       EmitAlignment(WordSize == 4 ? Align(4) : Align(8));
601       OutStreamer->EmitIntValue(4, 4 /*size*/); // data size for "GNU\0"
602       OutStreamer->EmitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
603       OutStreamer->EmitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
604       OutStreamer->EmitBytes(StringRef("GNU", 4)); // note name
605 
606       // Emitting an Elf_Prop for the CET properties.
607       OutStreamer->EmitIntValue(ELF::GNU_PROPERTY_X86_FEATURE_1_AND, 4);
608       OutStreamer->EmitIntValue(4, 4);               // data size
609       OutStreamer->EmitIntValue(FeatureFlagsAnd, 4); // data
610       EmitAlignment(WordSize == 4 ? Align(4) : Align(8)); // padding
611 
612       OutStreamer->endSection(Nt);
613       OutStreamer->SwitchSection(Cur);
614     }
615   }
616 
617   if (TT.isOSBinFormatMachO())
618     OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
619 
620   if (TT.isOSBinFormatCOFF()) {
621     // Emit an absolute @feat.00 symbol.  This appears to be some kind of
622     // compiler features bitfield read by link.exe.
623     MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
624     OutStreamer->BeginCOFFSymbolDef(S);
625     OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
626     OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
627     OutStreamer->EndCOFFSymbolDef();
628     int64_t Feat00Flags = 0;
629 
630     if (TT.getArch() == Triple::x86) {
631       // According to the PE-COFF spec, the LSB of this value marks the object
632       // for "registered SEH".  This means that all SEH handler entry points
633       // must be registered in .sxdata.  Use of any unregistered handlers will
634       // cause the process to terminate immediately.  LLVM does not know how to
635       // register any SEH handlers, so its object files should be safe.
636       Feat00Flags |= 1;
637     }
638 
639     if (M.getModuleFlag("cfguard"))
640       Feat00Flags |= 0x800; // Object is CFG-aware.
641 
642     OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
643     OutStreamer->EmitAssignment(
644         S, MCConstantExpr::create(Feat00Flags, MMI->getContext()));
645   }
646   OutStreamer->EmitSyntaxDirective();
647 
648   // If this is not inline asm and we're in 16-bit
649   // mode prefix assembly with .code16.
650   bool is16 = TT.getEnvironment() == Triple::CODE16;
651   if (M.getModuleInlineAsm().empty() && is16)
652     OutStreamer->EmitAssemblerFlag(MCAF_Code16);
653 }
654 
655 static void
656 emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
657                          MachineModuleInfoImpl::StubValueTy &MCSym) {
658   // L_foo$stub:
659   OutStreamer.EmitLabel(StubLabel);
660   //   .indirect_symbol _foo
661   OutStreamer.EmitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
662 
663   if (MCSym.getInt())
664     // External to current translation unit.
665     OutStreamer.EmitIntValue(0, 4/*size*/);
666   else
667     // Internal to current translation unit.
668     //
669     // When we place the LSDA into the TEXT section, the type info
670     // pointers need to be indirect and pc-rel. We accomplish this by
671     // using NLPs; however, sometimes the types are local to the file.
672     // We need to fill in the value for the NLP in those cases.
673     OutStreamer.EmitValue(
674         MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
675         4 /*size*/);
676 }
677 
678 static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
679 
680   MachineModuleInfoMachO &MMIMacho =
681       MMI->getObjFileInfo<MachineModuleInfoMachO>();
682 
683   // Output stubs for dynamically-linked functions.
684   MachineModuleInfoMachO::SymbolListTy Stubs;
685 
686   // Output stubs for external and common global variables.
687   Stubs = MMIMacho.GetGVStubList();
688   if (!Stubs.empty()) {
689     OutStreamer.SwitchSection(MMI->getContext().getMachOSection(
690         "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
691         SectionKind::getMetadata()));
692 
693     for (auto &Stub : Stubs)
694       emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
695 
696     Stubs.clear();
697     OutStreamer.AddBlankLine();
698   }
699 }
700 
701 void X86AsmPrinter::EmitEndOfAsmFile(Module &M) {
702   const Triple &TT = TM.getTargetTriple();
703 
704   if (TT.isOSBinFormatMachO()) {
705     // Mach-O uses non-lazy symbol stubs to encode per-TU information into
706     // global table for symbol lookup.
707     emitNonLazyStubs(MMI, *OutStreamer);
708 
709     // Emit stack and fault map information.
710     emitStackMaps(SM);
711     FM.serializeToFaultMapSection();
712 
713     // This flag tells the linker that no global symbols contain code that fall
714     // through to other global symbols (e.g. an implementation of multiple entry
715     // points). If this doesn't occur, the linker can safely perform dead code
716     // stripping. Since LLVM never generates code that does this, it is always
717     // safe to set.
718     OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
719   } else if (TT.isOSBinFormatCOFF()) {
720     if (MMI->usesMSVCFloatingPoint()) {
721       // In Windows' libcmt.lib, there is a file which is linked in only if the
722       // symbol _fltused is referenced. Linking this in causes some
723       // side-effects:
724       //
725       // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
726       // 64-bit mantissas at program start.
727       //
728       // 2. It links in support routines for floating-point in scanf and printf.
729       //
730       // MSVC emits an undefined reference to _fltused when there are any
731       // floating point operations in the program (including calls). A program
732       // that only has: `scanf("%f", &global_float);` may fail to trigger this,
733       // but oh well...that's a documented issue.
734       StringRef SymbolName =
735           (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
736       MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
737       OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
738       return;
739     }
740     emitStackMaps(SM);
741   } else if (TT.isOSBinFormatELF()) {
742     emitStackMaps(SM);
743     FM.serializeToFaultMapSection();
744   }
745 }
746 
747 //===----------------------------------------------------------------------===//
748 // Target Registry Stuff
749 //===----------------------------------------------------------------------===//
750 
751 // Force static initialization.
752 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeX86AsmPrinter() {
753   RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
754   RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
755 }
756