X86AsmPrinter.cpp revision 355940 
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"
43using namespace llvm;
44
45X86AsmPrinter::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///
55bool 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
90void 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
100void 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.
111void 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
202void 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_GlobalAddress: {
222    if (IsATT)
223      O << '$';
224    PrintSymbolOperand(MO, O);
225    break;
226  }
227  case MachineOperand::MO_BlockAddress: {
228    MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
229    Sym->print(O, MAI);
230    break;
231  }
232  }
233}
234
235/// PrintModifiedOperand - Print subregisters based on supplied modifier,
236/// deferring to PrintOperand() if no modifier was supplied or if operand is not
237/// a register.
238void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
239                                         raw_ostream &O, const char *Modifier) {
240  const MachineOperand &MO = MI->getOperand(OpNo);
241  if (!Modifier || MO.getType() != MachineOperand::MO_Register)
242    return PrintOperand(MI, OpNo, O);
243  if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
244    O << '%';
245  unsigned Reg = MO.getReg();
246  if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
247    unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
248        (strcmp(Modifier+6,"32") == 0) ? 32 :
249        (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
250    Reg = getX86SubSuperRegister(Reg, Size);
251  }
252  O << X86ATTInstPrinter::getRegisterName(Reg);
253}
254
255/// PrintPCRelImm - This is used to print an immediate value that ends up
256/// being encoded as a pc-relative value.  These print slightly differently, for
257/// example, a $ is not emitted.
258void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
259                                  raw_ostream &O) {
260  const MachineOperand &MO = MI->getOperand(OpNo);
261  switch (MO.getType()) {
262  default: llvm_unreachable("Unknown pcrel immediate operand");
263  case MachineOperand::MO_Register:
264    // pc-relativeness was handled when computing the value in the reg.
265    PrintOperand(MI, OpNo, O);
266    return;
267  case MachineOperand::MO_Immediate:
268    O << MO.getImm();
269    return;
270  case MachineOperand::MO_GlobalAddress:
271    PrintSymbolOperand(MO, O);
272    return;
273  }
274}
275
276void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
277                                         raw_ostream &O, const char *Modifier) {
278  const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
279  const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
280  const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
281
282  // If we really don't want to print out (rip), don't.
283  bool HasBaseReg = BaseReg.getReg() != 0;
284  if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
285      BaseReg.getReg() == X86::RIP)
286    HasBaseReg = false;
287
288  // HasParenPart - True if we will print out the () part of the mem ref.
289  bool HasParenPart = IndexReg.getReg() || HasBaseReg;
290
291  switch (DispSpec.getType()) {
292  default:
293    llvm_unreachable("unknown operand type!");
294  case MachineOperand::MO_Immediate: {
295    int DispVal = DispSpec.getImm();
296    if (DispVal || !HasParenPart)
297      O << DispVal;
298    break;
299  }
300  case MachineOperand::MO_GlobalAddress:
301  case MachineOperand::MO_ConstantPoolIndex:
302    PrintSymbolOperand(DispSpec, O);
303    break;
304  }
305
306  if (Modifier && strcmp(Modifier, "H") == 0)
307    O << "+8";
308
309  if (HasParenPart) {
310    assert(IndexReg.getReg() != X86::ESP &&
311           "X86 doesn't allow scaling by ESP");
312
313    O << '(';
314    if (HasBaseReg)
315      PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
316
317    if (IndexReg.getReg()) {
318      O << ',';
319      PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
320      unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
321      if (ScaleVal != 1)
322        O << ',' << ScaleVal;
323    }
324    O << ')';
325  }
326}
327
328void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
329                                      raw_ostream &O, const char *Modifier) {
330  assert(isMem(*MI, OpNo) && "Invalid memory reference!");
331  const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
332  if (Segment.getReg()) {
333    PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
334    O << ':';
335  }
336  PrintLeaMemReference(MI, OpNo, O, Modifier);
337}
338
339void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
340                                           unsigned OpNo, raw_ostream &O) {
341  const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
342  unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
343  const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
344  const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
345  const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
346
347  // If this has a segment register, print it.
348  if (SegReg.getReg()) {
349    PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
350    O << ':';
351  }
352
353  O << '[';
354
355  bool NeedPlus = false;
356  if (BaseReg.getReg()) {
357    PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
358    NeedPlus = true;
359  }
360
361  if (IndexReg.getReg()) {
362    if (NeedPlus) O << " + ";
363    if (ScaleVal != 1)
364      O << ScaleVal << '*';
365    PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
366    NeedPlus = true;
367  }
368
369  if (!DispSpec.isImm()) {
370    if (NeedPlus) O << " + ";
371    PrintOperand(MI, OpNo + X86::AddrDisp, O);
372  } else {
373    int64_t DispVal = DispSpec.getImm();
374    if (DispVal || (!IndexReg.getReg() && !BaseReg.getReg())) {
375      if (NeedPlus) {
376        if (DispVal > 0)
377          O << " + ";
378        else {
379          O << " - ";
380          DispVal = -DispVal;
381        }
382      }
383      O << DispVal;
384    }
385  }
386  O << ']';
387}
388
389static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
390                              char Mode, raw_ostream &O) {
391  unsigned Reg = MO.getReg();
392  bool EmitPercent = true;
393
394  if (!X86::GR8RegClass.contains(Reg) &&
395      !X86::GR16RegClass.contains(Reg) &&
396      !X86::GR32RegClass.contains(Reg) &&
397      !X86::GR64RegClass.contains(Reg))
398    return true;
399
400  switch (Mode) {
401  default: return true;  // Unknown mode.
402  case 'b': // Print QImode register
403    Reg = getX86SubSuperRegister(Reg, 8);
404    break;
405  case 'h': // Print QImode high register
406    Reg = getX86SubSuperRegister(Reg, 8, true);
407    break;
408  case 'w': // Print HImode register
409    Reg = getX86SubSuperRegister(Reg, 16);
410    break;
411  case 'k': // Print SImode register
412    Reg = getX86SubSuperRegister(Reg, 32);
413    break;
414  case 'V':
415    EmitPercent = false;
416    LLVM_FALLTHROUGH;
417  case 'q':
418    // Print 64-bit register names if 64-bit integer registers are available.
419    // Otherwise, print 32-bit register names.
420    Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
421    break;
422  }
423
424  if (EmitPercent)
425    O << '%';
426
427  O << X86ATTInstPrinter::getRegisterName(Reg);
428  return false;
429}
430
431/// PrintAsmOperand - Print out an operand for an inline asm expression.
432///
433bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
434                                    const char *ExtraCode, raw_ostream &O) {
435  // Does this asm operand have a single letter operand modifier?
436  if (ExtraCode && ExtraCode[0]) {
437    if (ExtraCode[1] != 0) return true; // Unknown modifier.
438
439    const MachineOperand &MO = MI->getOperand(OpNo);
440
441    switch (ExtraCode[0]) {
442    default:
443      // See if this is a generic print operand
444      return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
445    case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
446      switch (MO.getType()) {
447      default:
448        return true;
449      case MachineOperand::MO_Immediate:
450        O << MO.getImm();
451        return false;
452      case MachineOperand::MO_ConstantPoolIndex:
453      case MachineOperand::MO_JumpTableIndex:
454      case MachineOperand::MO_ExternalSymbol:
455        llvm_unreachable("unexpected operand type!");
456      case MachineOperand::MO_GlobalAddress:
457        PrintSymbolOperand(MO, O);
458        if (Subtarget->isPICStyleRIPRel())
459          O << "(%rip)";
460        return false;
461      case MachineOperand::MO_Register:
462        O << '(';
463        PrintOperand(MI, OpNo, O);
464        O << ')';
465        return false;
466      }
467
468    case 'c': // Don't print "$" before a global var name or constant.
469      switch (MO.getType()) {
470      default:
471        PrintOperand(MI, OpNo, O);
472        break;
473      case MachineOperand::MO_Immediate:
474        O << MO.getImm();
475        break;
476      case MachineOperand::MO_ConstantPoolIndex:
477      case MachineOperand::MO_JumpTableIndex:
478      case MachineOperand::MO_ExternalSymbol:
479        llvm_unreachable("unexpected operand type!");
480      case MachineOperand::MO_GlobalAddress:
481        PrintSymbolOperand(MO, O);
482        break;
483      }
484      return false;
485
486    case 'A': // Print '*' before a register (it must be a register)
487      if (MO.isReg()) {
488        O << '*';
489        PrintOperand(MI, OpNo, O);
490        return false;
491      }
492      return true;
493
494    case 'b': // Print QImode register
495    case 'h': // Print QImode high register
496    case 'w': // Print HImode register
497    case 'k': // Print SImode register
498    case 'q': // Print DImode register
499    case 'V': // Print native register without '%'
500      if (MO.isReg())
501        return printAsmMRegister(*this, MO, ExtraCode[0], O);
502      PrintOperand(MI, OpNo, O);
503      return false;
504
505    case 'P': // This is the operand of a call, treat specially.
506      PrintPCRelImm(MI, OpNo, O);
507      return false;
508
509    case 'n': // Negate the immediate or print a '-' before the operand.
510      // Note: this is a temporary solution. It should be handled target
511      // independently as part of the 'MC' work.
512      if (MO.isImm()) {
513        O << -MO.getImm();
514        return false;
515      }
516      O << '-';
517    }
518  }
519
520  PrintOperand(MI, OpNo, O);
521  return false;
522}
523
524bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
525                                          const char *ExtraCode,
526                                          raw_ostream &O) {
527  if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
528    PrintIntelMemReference(MI, OpNo, O);
529    return false;
530  }
531
532  if (ExtraCode && ExtraCode[0]) {
533    if (ExtraCode[1] != 0) return true; // Unknown modifier.
534
535    switch (ExtraCode[0]) {
536    default: return true;  // Unknown modifier.
537    case 'b': // Print QImode register
538    case 'h': // Print QImode high register
539    case 'w': // Print HImode register
540    case 'k': // Print SImode register
541    case 'q': // Print SImode register
542      // These only apply to registers, ignore on mem.
543      break;
544    case 'H':
545      PrintMemReference(MI, OpNo, O, "H");
546      return false;
547    case 'P': // Don't print @PLT, but do print as memory.
548      PrintMemReference(MI, OpNo, O, "no-rip");
549      return false;
550    }
551  }
552  PrintMemReference(MI, OpNo, O, nullptr);
553  return false;
554}
555
556void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
557  const Triple &TT = TM.getTargetTriple();
558
559  if (TT.isOSBinFormatELF()) {
560    // Assemble feature flags that may require creation of a note section.
561    unsigned FeatureFlagsAnd = 0;
562    if (M.getModuleFlag("cf-protection-branch"))
563      FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
564    if (M.getModuleFlag("cf-protection-return"))
565      FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
566
567    if (FeatureFlagsAnd) {
568      // Emit a .note.gnu.property section with the flags.
569      if (!TT.isArch32Bit() && !TT.isArch64Bit())
570        llvm_unreachable("CFProtection used on invalid architecture!");
571      MCSection *Cur = OutStreamer->getCurrentSectionOnly();
572      MCSection *Nt = MMI->getContext().getELFSection(
573          ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
574      OutStreamer->SwitchSection(Nt);
575
576      // Emitting note header.
577      int WordSize = TT.isArch64Bit() ? 8 : 4;
578      EmitAlignment(WordSize == 4 ? 2 : 3);
579      OutStreamer->EmitIntValue(4, 4 /*size*/); // data size for "GNU\0"
580      OutStreamer->EmitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
581      OutStreamer->EmitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
582      OutStreamer->EmitBytes(StringRef("GNU", 4)); // note name
583
584      // Emitting an Elf_Prop for the CET properties.
585      OutStreamer->EmitIntValue(ELF::GNU_PROPERTY_X86_FEATURE_1_AND, 4);
586      OutStreamer->EmitIntValue(4, 4);               // data size
587      OutStreamer->EmitIntValue(FeatureFlagsAnd, 4); // data
588      EmitAlignment(WordSize == 4 ? 2 : 3);          // padding
589
590      OutStreamer->endSection(Nt);
591      OutStreamer->SwitchSection(Cur);
592    }
593  }
594
595  if (TT.isOSBinFormatMachO())
596    OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
597
598  if (TT.isOSBinFormatCOFF()) {
599    // Emit an absolute @feat.00 symbol.  This appears to be some kind of
600    // compiler features bitfield read by link.exe.
601    MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
602    OutStreamer->BeginCOFFSymbolDef(S);
603    OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
604    OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
605    OutStreamer->EndCOFFSymbolDef();
606    int64_t Feat00Flags = 0;
607
608    if (TT.getArch() == Triple::x86) {
609      // According to the PE-COFF spec, the LSB of this value marks the object
610      // for "registered SEH".  This means that all SEH handler entry points
611      // must be registered in .sxdata.  Use of any unregistered handlers will
612      // cause the process to terminate immediately.  LLVM does not know how to
613      // register any SEH handlers, so its object files should be safe.
614      Feat00Flags |= 1;
615    }
616
617    if (M.getModuleFlag("cfguardtable"))
618      Feat00Flags |= 0x800; // Object is CFG-aware.
619
620    OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
621    OutStreamer->EmitAssignment(
622        S, MCConstantExpr::create(Feat00Flags, MMI->getContext()));
623  }
624  OutStreamer->EmitSyntaxDirective();
625
626  // If this is not inline asm and we're in 16-bit
627  // mode prefix assembly with .code16.
628  bool is16 = TT.getEnvironment() == Triple::CODE16;
629  if (M.getModuleInlineAsm().empty() && is16)
630    OutStreamer->EmitAssemblerFlag(MCAF_Code16);
631}
632
633static void
634emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
635                         MachineModuleInfoImpl::StubValueTy &MCSym) {
636  // L_foo$stub:
637  OutStreamer.EmitLabel(StubLabel);
638  //   .indirect_symbol _foo
639  OutStreamer.EmitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
640
641  if (MCSym.getInt())
642    // External to current translation unit.
643    OutStreamer.EmitIntValue(0, 4/*size*/);
644  else
645    // Internal to current translation unit.
646    //
647    // When we place the LSDA into the TEXT section, the type info
648    // pointers need to be indirect and pc-rel. We accomplish this by
649    // using NLPs; however, sometimes the types are local to the file.
650    // We need to fill in the value for the NLP in those cases.
651    OutStreamer.EmitValue(
652        MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
653        4 /*size*/);
654}
655
656static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
657
658  MachineModuleInfoMachO &MMIMacho =
659      MMI->getObjFileInfo<MachineModuleInfoMachO>();
660
661  // Output stubs for dynamically-linked functions.
662  MachineModuleInfoMachO::SymbolListTy Stubs;
663
664  // Output stubs for external and common global variables.
665  Stubs = MMIMacho.GetGVStubList();
666  if (!Stubs.empty()) {
667    OutStreamer.SwitchSection(MMI->getContext().getMachOSection(
668        "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
669        SectionKind::getMetadata()));
670
671    for (auto &Stub : Stubs)
672      emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
673
674    Stubs.clear();
675    OutStreamer.AddBlankLine();
676  }
677}
678
679void X86AsmPrinter::EmitEndOfAsmFile(Module &M) {
680  const Triple &TT = TM.getTargetTriple();
681
682  if (TT.isOSBinFormatMachO()) {
683    // Mach-O uses non-lazy symbol stubs to encode per-TU information into
684    // global table for symbol lookup.
685    emitNonLazyStubs(MMI, *OutStreamer);
686
687    // Emit stack and fault map information.
688    emitStackMaps(SM);
689    FM.serializeToFaultMapSection();
690
691    // This flag tells the linker that no global symbols contain code that fall
692    // through to other global symbols (e.g. an implementation of multiple entry
693    // points). If this doesn't occur, the linker can safely perform dead code
694    // stripping. Since LLVM never generates code that does this, it is always
695    // safe to set.
696    OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
697  } else if (TT.isOSBinFormatCOFF()) {
698    if (MMI->usesMSVCFloatingPoint()) {
699      // In Windows' libcmt.lib, there is a file which is linked in only if the
700      // symbol _fltused is referenced. Linking this in causes some
701      // side-effects:
702      //
703      // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
704      // 64-bit mantissas at program start.
705      //
706      // 2. It links in support routines for floating-point in scanf and printf.
707      //
708      // MSVC emits an undefined reference to _fltused when there are any
709      // floating point operations in the program (including calls). A program
710      // that only has: `scanf("%f", &global_float);` may fail to trigger this,
711      // but oh well...that's a documented issue.
712      StringRef SymbolName =
713          (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
714      MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
715      OutStreamer->EmitSymbolAttribute(S, MCSA_Global);
716      return;
717    }
718    emitStackMaps(SM);
719  } else if (TT.isOSBinFormatELF()) {
720    emitStackMaps(SM);
721    FM.serializeToFaultMapSection();
722  }
723}
724
725//===----------------------------------------------------------------------===//
726// Target Registry Stuff
727//===----------------------------------------------------------------------===//
728
729// Force static initialization.
730extern "C" void LLVMInitializeX86AsmPrinter() {
731  RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
732  RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
733}
734