1 //===-- X86AsmPrinter.cpp - Convert X86 LLVM code to AT&T assembly --------===//
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 X86 machine code.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "X86AsmPrinter.h"
16 #include "InstPrinter/X86ATTInstPrinter.h"
17 #include "X86.h"
18 #include "X86COFFMachineModuleInfo.h"
19 #include "X86MachineFunctionInfo.h"
20 #include "X86TargetMachine.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/CodeGen/MachineJumpTableInfo.h"
23 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
24 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
25 #include "llvm/DebugInfo.h"
26 #include "llvm/IR/CallingConv.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/Mangler.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/IR/Type.h"
31 #include "llvm/MC/MCAsmInfo.h"
32 #include "llvm/MC/MCContext.h"
33 #include "llvm/MC/MCExpr.h"
34 #include "llvm/MC/MCSectionMachO.h"
35 #include "llvm/MC/MCStreamer.h"
36 #include "llvm/MC/MCSymbol.h"
37 #include "llvm/Support/COFF.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/ErrorHandling.h"
40 #include "llvm/Support/TargetRegistry.h"
41 #include "llvm/Target/TargetOptions.h"
42 using namespace llvm;
43 
44 //===----------------------------------------------------------------------===//
45 // Primitive Helper Functions.
46 //===----------------------------------------------------------------------===//
47 
48 /// runOnMachineFunction - Emit the function body.
49 ///
50 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
51   SetupMachineFunction(MF);
52 
53   if (Subtarget->isTargetCOFF()) {
54     bool Intrn = MF.getFunction()->hasInternalLinkage();
55     OutStreamer.BeginCOFFSymbolDef(CurrentFnSym);
56     OutStreamer.EmitCOFFSymbolStorageClass(Intrn ? COFF::IMAGE_SYM_CLASS_STATIC
57                                               : COFF::IMAGE_SYM_CLASS_EXTERNAL);
58     OutStreamer.EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
59                                                << COFF::SCT_COMPLEX_TYPE_SHIFT);
60     OutStreamer.EndCOFFSymbolDef();
61   }
62 
63   // Have common code print out the function header with linkage info etc.
64   EmitFunctionHeader();
65 
66   // Emit the rest of the function body.
67   EmitFunctionBody();
68 
69   // We didn't modify anything.
70   return false;
71 }
72 
73 /// printSymbolOperand - Print a raw symbol reference operand.  This handles
74 /// jump tables, constant pools, global address and external symbols, all of
75 /// which print to a label with various suffixes for relocation types etc.
76 static void printSymbolOperand(X86AsmPrinter &P, const MachineOperand &MO,
77                                raw_ostream &O) {
78   switch (MO.getType()) {
79   default: llvm_unreachable("unknown symbol type!");
80   case MachineOperand::MO_ConstantPoolIndex:
81     O << *P.GetCPISymbol(MO.getIndex());
82     P.printOffset(MO.getOffset(), O);
83     break;
84   case MachineOperand::MO_GlobalAddress: {
85     const GlobalValue *GV = MO.getGlobal();
86 
87     MCSymbol *GVSym;
88     if (MO.getTargetFlags() == X86II::MO_DARWIN_STUB)
89       GVSym = P.getSymbolWithGlobalValueBase(GV, "$stub");
90     else if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
91              MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE ||
92              MO.getTargetFlags() == X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE)
93       GVSym = P.getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
94     else
95       GVSym = P.getSymbol(GV);
96 
97     // Handle dllimport linkage.
98     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
99       GVSym =
100           P.OutContext.GetOrCreateSymbol(Twine("__imp_") + GVSym->getName());
101 
102     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
103         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
104       MCSymbol *Sym = P.getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
105       MachineModuleInfoImpl::StubValueTy &StubSym =
106           P.MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
107       if (StubSym.getPointer() == 0)
108         StubSym = MachineModuleInfoImpl::
109           StubValueTy(P.getSymbol(GV), !GV->hasInternalLinkage());
110     } else if (MO.getTargetFlags() == X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE){
111       MCSymbol *Sym = P.getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
112       MachineModuleInfoImpl::StubValueTy &StubSym =
113           P.MMI->getObjFileInfo<MachineModuleInfoMachO>().getHiddenGVStubEntry(
114               Sym);
115       if (StubSym.getPointer() == 0)
116         StubSym = MachineModuleInfoImpl::
117           StubValueTy(P.getSymbol(GV), !GV->hasInternalLinkage());
118     } else if (MO.getTargetFlags() == X86II::MO_DARWIN_STUB) {
119       MCSymbol *Sym = P.getSymbolWithGlobalValueBase(GV, "$stub");
120       MachineModuleInfoImpl::StubValueTy &StubSym =
121           P.MMI->getObjFileInfo<MachineModuleInfoMachO>().getFnStubEntry(Sym);
122       if (StubSym.getPointer() == 0)
123         StubSym = MachineModuleInfoImpl::
124           StubValueTy(P.getSymbol(GV), !GV->hasInternalLinkage());
125     }
126 
127     // If the name begins with a dollar-sign, enclose it in parens.  We do this
128     // to avoid having it look like an integer immediate to the assembler.
129     if (GVSym->getName()[0] != '$')
130       O << *GVSym;
131     else
132       O << '(' << *GVSym << ')';
133     P.printOffset(MO.getOffset(), O);
134     break;
135   }
136   }
137 
138   switch (MO.getTargetFlags()) {
139   default:
140     llvm_unreachable("Unknown target flag on GV operand");
141   case X86II::MO_NO_FLAG:    // No flag.
142     break;
143   case X86II::MO_DARWIN_NONLAZY:
144   case X86II::MO_DLLIMPORT:
145   case X86II::MO_DARWIN_STUB:
146     // These affect the name of the symbol, not any suffix.
147     break;
148   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
149     O << " + [.-" << *P.MF->getPICBaseSymbol() << ']';
150     break;
151   case X86II::MO_PIC_BASE_OFFSET:
152   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
153   case X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE:
154     O << '-' << *P.MF->getPICBaseSymbol();
155     break;
156   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
157   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
158   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
159   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
160   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
161   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
162   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
163   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
164   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
165   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
166   case X86II::MO_GOT:       O << "@GOT";       break;
167   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
168   case X86II::MO_PLT:       O << "@PLT";       break;
169   case X86II::MO_TLVP:      O << "@TLVP";      break;
170   case X86II::MO_TLVP_PIC_BASE:
171     O << "@TLVP" << '-' << *P.MF->getPICBaseSymbol();
172     break;
173   case X86II::MO_SECREL:    O << "@SECREL32";  break;
174   }
175 }
176 
177 static void printOperand(X86AsmPrinter &P, const MachineInstr *MI,
178                          unsigned OpNo, raw_ostream &O,
179                          const char *Modifier = 0, unsigned AsmVariant = 0);
180 
181 /// printPCRelImm - This is used to print an immediate value that ends up
182 /// being encoded as a pc-relative value.  These print slightly differently, for
183 /// example, a $ is not emitted.
184 static void printPCRelImm(X86AsmPrinter &P, const MachineInstr *MI,
185                           unsigned OpNo, raw_ostream &O) {
186   const MachineOperand &MO = MI->getOperand(OpNo);
187   switch (MO.getType()) {
188   default: llvm_unreachable("Unknown pcrel immediate operand");
189   case MachineOperand::MO_Register:
190     // pc-relativeness was handled when computing the value in the reg.
191     printOperand(P, MI, OpNo, O);
192     return;
193   case MachineOperand::MO_Immediate:
194     O << MO.getImm();
195     return;
196   case MachineOperand::MO_GlobalAddress:
197     printSymbolOperand(P, MO, O);
198     return;
199   }
200 }
201 
202 static void printOperand(X86AsmPrinter &P, const MachineInstr *MI,
203                          unsigned OpNo, raw_ostream &O, const char *Modifier,
204                          unsigned AsmVariant) {
205   const MachineOperand &MO = MI->getOperand(OpNo);
206   switch (MO.getType()) {
207   default: llvm_unreachable("unknown operand type!");
208   case MachineOperand::MO_Register: {
209     // FIXME: Enumerating AsmVariant, so we can remove magic number.
210     if (AsmVariant == 0) O << '%';
211     unsigned Reg = MO.getReg();
212     if (Modifier && strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
213       MVT::SimpleValueType VT = (strcmp(Modifier+6,"64") == 0) ?
214         MVT::i64 : ((strcmp(Modifier+6, "32") == 0) ? MVT::i32 :
215                     ((strcmp(Modifier+6,"16") == 0) ? MVT::i16 : MVT::i8));
216       Reg = getX86SubSuperRegister(Reg, VT);
217     }
218     O << X86ATTInstPrinter::getRegisterName(Reg);
219     return;
220   }
221 
222   case MachineOperand::MO_Immediate:
223     if (AsmVariant == 0) O << '$';
224     O << MO.getImm();
225     return;
226 
227   case MachineOperand::MO_GlobalAddress: {
228     if (AsmVariant == 0) O << '$';
229     printSymbolOperand(P, MO, O);
230     break;
231   }
232   }
233 }
234 
235 static void printLeaMemReference(X86AsmPrinter &P, const MachineInstr *MI,
236                                  unsigned Op, raw_ostream &O,
237                                  const char *Modifier = NULL) {
238   const MachineOperand &BaseReg  = MI->getOperand(Op);
239   const MachineOperand &IndexReg = MI->getOperand(Op+2);
240   const MachineOperand &DispSpec = MI->getOperand(Op+3);
241 
242   // If we really don't want to print out (rip), don't.
243   bool HasBaseReg = BaseReg.getReg() != 0;
244   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
245       BaseReg.getReg() == X86::RIP)
246     HasBaseReg = false;
247 
248   // HasParenPart - True if we will print out the () part of the mem ref.
249   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
250 
251   switch (DispSpec.getType()) {
252   default:
253     llvm_unreachable("unknown operand type!");
254   case MachineOperand::MO_Immediate: {
255     int DispVal = DispSpec.getImm();
256     if (DispVal || !HasParenPart)
257       O << DispVal;
258     break;
259   }
260   case MachineOperand::MO_GlobalAddress:
261   case MachineOperand::MO_ConstantPoolIndex:
262     printSymbolOperand(P, MI->getOperand(Op + 3), O);
263   }
264 
265   if (Modifier && strcmp(Modifier, "H") == 0)
266     O << "+8";
267 
268   if (HasParenPart) {
269     assert(IndexReg.getReg() != X86::ESP &&
270            "X86 doesn't allow scaling by ESP");
271 
272     O << '(';
273     if (HasBaseReg)
274       printOperand(P, MI, Op, O, Modifier);
275 
276     if (IndexReg.getReg()) {
277       O << ',';
278       printOperand(P, MI, Op+2, O, Modifier);
279       unsigned ScaleVal = MI->getOperand(Op+1).getImm();
280       if (ScaleVal != 1)
281         O << ',' << ScaleVal;
282     }
283     O << ')';
284   }
285 }
286 
287 static void printMemReference(X86AsmPrinter &P, const MachineInstr *MI,
288                               unsigned Op, raw_ostream &O,
289                               const char *Modifier = NULL) {
290   assert(isMem(MI, Op) && "Invalid memory reference!");
291   const MachineOperand &Segment = MI->getOperand(Op+4);
292   if (Segment.getReg()) {
293     printOperand(P, MI, Op+4, O, Modifier);
294     O << ':';
295   }
296   printLeaMemReference(P, MI, Op, O, Modifier);
297 }
298 
299 static void printIntelMemReference(X86AsmPrinter &P, const MachineInstr *MI,
300                                    unsigned Op, raw_ostream &O,
301                                    const char *Modifier = NULL,
302                                    unsigned AsmVariant = 1) {
303   const MachineOperand &BaseReg  = MI->getOperand(Op);
304   unsigned ScaleVal = MI->getOperand(Op+1).getImm();
305   const MachineOperand &IndexReg = MI->getOperand(Op+2);
306   const MachineOperand &DispSpec = MI->getOperand(Op+3);
307   const MachineOperand &SegReg   = MI->getOperand(Op+4);
308 
309   // If this has a segment register, print it.
310   if (SegReg.getReg()) {
311     printOperand(P, MI, Op+4, O, Modifier, AsmVariant);
312     O << ':';
313   }
314 
315   O << '[';
316 
317   bool NeedPlus = false;
318   if (BaseReg.getReg()) {
319     printOperand(P, MI, Op, O, Modifier, AsmVariant);
320     NeedPlus = true;
321   }
322 
323   if (IndexReg.getReg()) {
324     if (NeedPlus) O << " + ";
325     if (ScaleVal != 1)
326       O << ScaleVal << '*';
327     printOperand(P, MI, Op+2, O, Modifier, AsmVariant);
328     NeedPlus = true;
329   }
330 
331   if (!DispSpec.isImm()) {
332     if (NeedPlus) O << " + ";
333     printOperand(P, MI, Op+3, O, Modifier, AsmVariant);
334   } else {
335     int64_t DispVal = DispSpec.getImm();
336     if (DispVal || (!IndexReg.getReg() && !BaseReg.getReg())) {
337       if (NeedPlus) {
338         if (DispVal > 0)
339           O << " + ";
340         else {
341           O << " - ";
342           DispVal = -DispVal;
343         }
344       }
345       O << DispVal;
346     }
347   }
348   O << ']';
349 }
350 
351 static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
352                               char Mode, raw_ostream &O) {
353   unsigned Reg = MO.getReg();
354   switch (Mode) {
355   default: return true;  // Unknown mode.
356   case 'b': // Print QImode register
357     Reg = getX86SubSuperRegister(Reg, MVT::i8);
358     break;
359   case 'h': // Print QImode high register
360     Reg = getX86SubSuperRegister(Reg, MVT::i8, true);
361     break;
362   case 'w': // Print HImode register
363     Reg = getX86SubSuperRegister(Reg, MVT::i16);
364     break;
365   case 'k': // Print SImode register
366     Reg = getX86SubSuperRegister(Reg, MVT::i32);
367     break;
368   case 'q': // Print DImode register
369     // FIXME: gcc will actually print e instead of r for 32-bit.
370     Reg = getX86SubSuperRegister(Reg, MVT::i64);
371     break;
372   }
373 
374   O << '%' << X86ATTInstPrinter::getRegisterName(Reg);
375   return false;
376 }
377 
378 /// PrintAsmOperand - Print out an operand for an inline asm expression.
379 ///
380 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
381                                     unsigned AsmVariant,
382                                     const char *ExtraCode, raw_ostream &O) {
383   // Does this asm operand have a single letter operand modifier?
384   if (ExtraCode && ExtraCode[0]) {
385     if (ExtraCode[1] != 0) return true; // Unknown modifier.
386 
387     const MachineOperand &MO = MI->getOperand(OpNo);
388 
389     switch (ExtraCode[0]) {
390     default:
391       // See if this is a generic print operand
392       return AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, O);
393     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
394       switch (MO.getType()) {
395       default:
396         return true;
397       case MachineOperand::MO_Immediate:
398         O << MO.getImm();
399         return false;
400       case MachineOperand::MO_ConstantPoolIndex:
401       case MachineOperand::MO_JumpTableIndex:
402       case MachineOperand::MO_ExternalSymbol:
403         llvm_unreachable("unexpected operand type!");
404       case MachineOperand::MO_GlobalAddress:
405         printSymbolOperand(*this, MO, O);
406         if (Subtarget->isPICStyleRIPRel())
407           O << "(%rip)";
408         return false;
409       case MachineOperand::MO_Register:
410         O << '(';
411         printOperand(*this, MI, OpNo, O);
412         O << ')';
413         return false;
414       }
415 
416     case 'c': // Don't print "$" before a global var name or constant.
417       switch (MO.getType()) {
418       default:
419         printOperand(*this, MI, OpNo, O);
420         break;
421       case MachineOperand::MO_Immediate:
422         O << MO.getImm();
423         break;
424       case MachineOperand::MO_ConstantPoolIndex:
425       case MachineOperand::MO_JumpTableIndex:
426       case MachineOperand::MO_ExternalSymbol:
427         llvm_unreachable("unexpected operand type!");
428       case MachineOperand::MO_GlobalAddress:
429         printSymbolOperand(*this, MO, O);
430         break;
431       }
432       return false;
433 
434     case 'A': // Print '*' before a register (it must be a register)
435       if (MO.isReg()) {
436         O << '*';
437         printOperand(*this, MI, OpNo, O);
438         return false;
439       }
440       return true;
441 
442     case 'b': // Print QImode register
443     case 'h': // Print QImode high register
444     case 'w': // Print HImode register
445     case 'k': // Print SImode register
446     case 'q': // Print DImode register
447       if (MO.isReg())
448         return printAsmMRegister(*this, MO, ExtraCode[0], O);
449       printOperand(*this, MI, OpNo, O);
450       return false;
451 
452     case 'P': // This is the operand of a call, treat specially.
453       printPCRelImm(*this, MI, OpNo, O);
454       return false;
455 
456     case 'n':  // Negate the immediate or print a '-' before the operand.
457       // Note: this is a temporary solution. It should be handled target
458       // independently as part of the 'MC' work.
459       if (MO.isImm()) {
460         O << -MO.getImm();
461         return false;
462       }
463       O << '-';
464     }
465   }
466 
467   printOperand(*this, MI, OpNo, O, /*Modifier*/ 0, AsmVariant);
468   return false;
469 }
470 
471 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
472                                           unsigned OpNo, unsigned AsmVariant,
473                                           const char *ExtraCode,
474                                           raw_ostream &O) {
475   if (AsmVariant) {
476     printIntelMemReference(*this, MI, OpNo, O);
477     return false;
478   }
479 
480   if (ExtraCode && ExtraCode[0]) {
481     if (ExtraCode[1] != 0) return true; // Unknown modifier.
482 
483     switch (ExtraCode[0]) {
484     default: return true;  // Unknown modifier.
485     case 'b': // Print QImode register
486     case 'h': // Print QImode high register
487     case 'w': // Print HImode register
488     case 'k': // Print SImode register
489     case 'q': // Print SImode register
490       // These only apply to registers, ignore on mem.
491       break;
492     case 'H':
493       printMemReference(*this, MI, OpNo, O, "H");
494       return false;
495     case 'P': // Don't print @PLT, but do print as memory.
496       printMemReference(*this, MI, OpNo, O, "no-rip");
497       return false;
498     }
499   }
500   printMemReference(*this, MI, OpNo, O);
501   return false;
502 }
503 
504 void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
505   if (Subtarget->isTargetMacho())
506     OutStreamer.SwitchSection(getObjFileLowering().getTextSection());
507 
508   if (Subtarget->isTargetCOFF()) {
509     // Emit an absolute @feat.00 symbol.  This appears to be some kind of
510     // compiler features bitfield read by link.exe.
511     if (!Subtarget->is64Bit()) {
512       MCSymbol *S = MMI->getContext().GetOrCreateSymbol(StringRef("@feat.00"));
513       OutStreamer.BeginCOFFSymbolDef(S);
514       OutStreamer.EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
515       OutStreamer.EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
516       OutStreamer.EndCOFFSymbolDef();
517       // According to the PE-COFF spec, the LSB of this value marks the object
518       // for "registered SEH".  This means that all SEH handler entry points
519       // must be registered in .sxdata.  Use of any unregistered handlers will
520       // cause the process to terminate immediately.  LLVM does not know how to
521       // register any SEH handlers, so its object files should be safe.
522       S->setAbsolute();
523       OutStreamer.EmitSymbolAttribute(S, MCSA_Global);
524       OutStreamer.EmitAssignment(
525           S, MCConstantExpr::Create(int64_t(1), MMI->getContext()));
526     }
527   }
528 }
529 
530 
531 void X86AsmPrinter::EmitEndOfAsmFile(Module &M) {
532   if (Subtarget->isTargetMacho()) {
533     // All darwin targets use mach-o.
534     MachineModuleInfoMachO &MMIMacho =
535       MMI->getObjFileInfo<MachineModuleInfoMachO>();
536 
537     // Output stubs for dynamically-linked functions.
538     MachineModuleInfoMachO::SymbolListTy Stubs;
539 
540     Stubs = MMIMacho.GetFnStubList();
541     if (!Stubs.empty()) {
542       const MCSection *TheSection =
543         OutContext.getMachOSection("__IMPORT", "__jump_table",
544                                    MCSectionMachO::S_SYMBOL_STUBS |
545                                    MCSectionMachO::S_ATTR_SELF_MODIFYING_CODE |
546                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
547                                    5, SectionKind::getMetadata());
548       OutStreamer.SwitchSection(TheSection);
549 
550       for (unsigned i = 0, e = Stubs.size(); i != e; ++i) {
551         // L_foo$stub:
552         OutStreamer.EmitLabel(Stubs[i].first);
553         //   .indirect_symbol _foo
554         OutStreamer.EmitSymbolAttribute(Stubs[i].second.getPointer(),
555                                         MCSA_IndirectSymbol);
556         // hlt; hlt; hlt; hlt; hlt     hlt = 0xf4.
557         const char HltInsts[] = "\xf4\xf4\xf4\xf4\xf4";
558         OutStreamer.EmitBytes(StringRef(HltInsts, 5));
559       }
560 
561       Stubs.clear();
562       OutStreamer.AddBlankLine();
563     }
564 
565     // Output stubs for external and common global variables.
566     Stubs = MMIMacho.GetGVStubList();
567     if (!Stubs.empty()) {
568       const MCSection *TheSection =
569         OutContext.getMachOSection("__IMPORT", "__pointers",
570                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
571                                    SectionKind::getMetadata());
572       OutStreamer.SwitchSection(TheSection);
573 
574       for (unsigned i = 0, e = Stubs.size(); i != e; ++i) {
575         // L_foo$non_lazy_ptr:
576         OutStreamer.EmitLabel(Stubs[i].first);
577         // .indirect_symbol _foo
578         MachineModuleInfoImpl::StubValueTy &MCSym = Stubs[i].second;
579         OutStreamer.EmitSymbolAttribute(MCSym.getPointer(),
580                                         MCSA_IndirectSymbol);
581         // .long 0
582         if (MCSym.getInt())
583           // External to current translation unit.
584           OutStreamer.EmitIntValue(0, 4/*size*/);
585         else
586           // Internal to current translation unit.
587           //
588           // When we place the LSDA into the TEXT section, the type info
589           // pointers need to be indirect and pc-rel. We accomplish this by
590           // using NLPs.  However, sometimes the types are local to the file. So
591           // we need to fill in the value for the NLP in those cases.
592           OutStreamer.EmitValue(MCSymbolRefExpr::Create(MCSym.getPointer(),
593                                                         OutContext), 4/*size*/);
594       }
595       Stubs.clear();
596       OutStreamer.AddBlankLine();
597     }
598 
599     Stubs = MMIMacho.GetHiddenGVStubList();
600     if (!Stubs.empty()) {
601       OutStreamer.SwitchSection(getObjFileLowering().getDataSection());
602       EmitAlignment(2);
603 
604       for (unsigned i = 0, e = Stubs.size(); i != e; ++i) {
605         // L_foo$non_lazy_ptr:
606         OutStreamer.EmitLabel(Stubs[i].first);
607         // .long _foo
608         OutStreamer.EmitValue(MCSymbolRefExpr::
609                               Create(Stubs[i].second.getPointer(),
610                                      OutContext), 4/*size*/);
611       }
612       Stubs.clear();
613       OutStreamer.AddBlankLine();
614     }
615 
616     SM.serializeToStackMapSection();
617 
618     // Funny Darwin hack: This flag tells the linker that no global symbols
619     // contain code that falls through to other global symbols (e.g. the obvious
620     // implementation of multiple entry points).  If this doesn't occur, the
621     // linker can safely perform dead code stripping.  Since LLVM never
622     // generates code that does this, it is always safe to set.
623     OutStreamer.EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);
624   }
625 
626   if (Subtarget->isTargetWindows() && !Subtarget->isTargetCygMing() &&
627       MMI->usesVAFloatArgument()) {
628     StringRef SymbolName = Subtarget->is64Bit() ? "_fltused" : "__fltused";
629     MCSymbol *S = MMI->getContext().GetOrCreateSymbol(SymbolName);
630     OutStreamer.EmitSymbolAttribute(S, MCSA_Global);
631   }
632 
633   if (Subtarget->isTargetCOFF()) {
634     X86COFFMachineModuleInfo &COFFMMI =
635       MMI->getObjFileInfo<X86COFFMachineModuleInfo>();
636 
637     // Emit type information for external functions
638     typedef X86COFFMachineModuleInfo::externals_iterator externals_iterator;
639     for (externals_iterator I = COFFMMI.externals_begin(),
640                             E = COFFMMI.externals_end();
641                             I != E; ++I) {
642       OutStreamer.BeginCOFFSymbolDef(CurrentFnSym);
643       OutStreamer.EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_EXTERNAL);
644       OutStreamer.EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
645                                                << COFF::SCT_COMPLEX_TYPE_SHIFT);
646       OutStreamer.EndCOFFSymbolDef();
647     }
648 
649     // Necessary for dllexport support
650     std::vector<const MCSymbol*> DLLExportedFns, DLLExportedGlobals;
651 
652     for (Module::const_iterator I = M.begin(), E = M.end(); I != E; ++I)
653       if (I->hasDLLExportStorageClass())
654         DLLExportedFns.push_back(getSymbol(I));
655 
656     for (Module::const_global_iterator I = M.global_begin(),
657            E = M.global_end(); I != E; ++I)
658       if (I->hasDLLExportStorageClass())
659         DLLExportedGlobals.push_back(getSymbol(I));
660 
661     for (Module::const_alias_iterator I = M.alias_begin(), E = M.alias_end();
662                                       I != E; ++I) {
663       const GlobalValue *GV = I;
664       if (!GV->hasDLLExportStorageClass())
665         continue;
666 
667       while (const GlobalAlias *A = dyn_cast<GlobalAlias>(GV))
668         GV = A->getAliasedGlobal();
669 
670       if (isa<Function>(GV))
671         DLLExportedFns.push_back(getSymbol(I));
672       else if (isa<GlobalVariable>(GV))
673         DLLExportedGlobals.push_back(getSymbol(I));
674     }
675 
676     // Output linker support code for dllexported globals on windows.
677     if (!DLLExportedGlobals.empty() || !DLLExportedFns.empty()) {
678       const TargetLoweringObjectFileCOFF &TLOFCOFF =
679         static_cast<const TargetLoweringObjectFileCOFF&>(getObjFileLowering());
680 
681       OutStreamer.SwitchSection(TLOFCOFF.getDrectveSection());
682       SmallString<128> name;
683       for (unsigned i = 0, e = DLLExportedGlobals.size(); i != e; ++i) {
684         if (Subtarget->isTargetWindows())
685           name = " /EXPORT:";
686         else
687           name = " -export:";
688         name += DLLExportedGlobals[i]->getName();
689         if (Subtarget->isTargetWindows())
690           name += ",DATA";
691         else
692         name += ",data";
693         OutStreamer.EmitBytes(name);
694       }
695 
696       for (unsigned i = 0, e = DLLExportedFns.size(); i != e; ++i) {
697         if (Subtarget->isTargetWindows())
698           name = " /EXPORT:";
699         else
700           name = " -export:";
701         name += DLLExportedFns[i]->getName();
702         OutStreamer.EmitBytes(name);
703       }
704     }
705   }
706 
707   if (Subtarget->isTargetELF()) {
708     const TargetLoweringObjectFileELF &TLOFELF =
709       static_cast<const TargetLoweringObjectFileELF &>(getObjFileLowering());
710 
711     MachineModuleInfoELF &MMIELF = MMI->getObjFileInfo<MachineModuleInfoELF>();
712 
713     // Output stubs for external and common global variables.
714     MachineModuleInfoELF::SymbolListTy Stubs = MMIELF.GetGVStubList();
715     if (!Stubs.empty()) {
716       OutStreamer.SwitchSection(TLOFELF.getDataRelSection());
717       const DataLayout *TD = TM.getDataLayout();
718 
719       for (unsigned i = 0, e = Stubs.size(); i != e; ++i) {
720         OutStreamer.EmitLabel(Stubs[i].first);
721         OutStreamer.EmitSymbolValue(Stubs[i].second.getPointer(),
722                                     TD->getPointerSize());
723       }
724       Stubs.clear();
725     }
726   }
727 }
728 
729 //===----------------------------------------------------------------------===//
730 // Target Registry Stuff
731 //===----------------------------------------------------------------------===//
732 
733 // Force static initialization.
734 extern "C" void LLVMInitializeX86AsmPrinter() {
735   RegisterAsmPrinter<X86AsmPrinter> X(TheX86_32Target);
736   RegisterAsmPrinter<X86AsmPrinter> Y(TheX86_64Target);
737 }
738