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 "X86Subtarget.h"
22 #include "llvm/BinaryFormat/COFF.h"
23 #include "llvm/BinaryFormat/ELF.h"
24 #include "llvm/CodeGen/MachineConstantPool.h"
25 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
26 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/InlineAsm.h"
29 #include "llvm/IR/Mangler.h"
30 #include "llvm/IR/Module.h"
31 #include "llvm/IR/Type.h"
32 #include "llvm/MC/MCAsmInfo.h"
33 #include "llvm/MC/MCCodeEmitter.h"
34 #include "llvm/MC/MCContext.h"
35 #include "llvm/MC/MCExpr.h"
36 #include "llvm/MC/MCSectionCOFF.h"
37 #include "llvm/MC/MCSectionELF.h"
38 #include "llvm/MC/MCSectionMachO.h"
39 #include "llvm/MC/MCStreamer.h"
40 #include "llvm/MC/MCSymbol.h"
41 #include "llvm/MC/TargetRegistry.h"
42 #include "llvm/Support/Debug.h"
43 #include "llvm/Support/ErrorHandling.h"
44 #include "llvm/Support/MachineValueType.h"
45 #include "llvm/Target/TargetMachine.h"
46 
47 using namespace llvm;
48 
X86AsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)49 X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
50                              std::unique_ptr<MCStreamer> Streamer)
51     : AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this) {}
52 
53 //===----------------------------------------------------------------------===//
54 // Primitive Helper Functions.
55 //===----------------------------------------------------------------------===//
56 
57 /// runOnMachineFunction - Emit the function body.
58 ///
runOnMachineFunction(MachineFunction & MF)59 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
60   Subtarget = &MF.getSubtarget<X86Subtarget>();
61 
62   SMShadowTracker.startFunction(MF);
63   CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
64       *Subtarget->getInstrInfo(), MF.getContext()));
65 
66   EmitFPOData =
67       Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
68 
69   SetupMachineFunction(MF);
70 
71   if (Subtarget->isTargetCOFF()) {
72     bool Local = MF.getFunction().hasLocalLinkage();
73     OutStreamer->beginCOFFSymbolDef(CurrentFnSym);
74     OutStreamer->emitCOFFSymbolStorageClass(
75         Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
76     OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
77                                     << COFF::SCT_COMPLEX_TYPE_SHIFT);
78     OutStreamer->endCOFFSymbolDef();
79   }
80 
81   // Emit the rest of the function body.
82   emitFunctionBody();
83 
84   // Emit the XRay table for this function.
85   emitXRayTable();
86 
87   EmitFPOData = false;
88 
89   // We didn't modify anything.
90   return false;
91 }
92 
emitFunctionBodyStart()93 void X86AsmPrinter::emitFunctionBodyStart() {
94   if (EmitFPOData) {
95     if (auto *XTS =
96         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
97       XTS->emitFPOProc(
98           CurrentFnSym,
99           MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
100   }
101 }
102 
emitFunctionBodyEnd()103 void X86AsmPrinter::emitFunctionBodyEnd() {
104   if (EmitFPOData) {
105     if (auto *XTS =
106             static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
107       XTS->emitFPOEndProc();
108   }
109 }
110 
111 /// PrintSymbolOperand - Print a raw symbol reference operand.  This handles
112 /// jump tables, constant pools, global address and external symbols, all of
113 /// which print to a label with various suffixes for relocation types etc.
PrintSymbolOperand(const MachineOperand & MO,raw_ostream & O)114 void X86AsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
115                                        raw_ostream &O) {
116   switch (MO.getType()) {
117   default: llvm_unreachable("unknown symbol type!");
118   case MachineOperand::MO_ConstantPoolIndex:
119     GetCPISymbol(MO.getIndex())->print(O, MAI);
120     printOffset(MO.getOffset(), O);
121     break;
122   case MachineOperand::MO_GlobalAddress: {
123     const GlobalValue *GV = MO.getGlobal();
124 
125     MCSymbol *GVSym;
126     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
127         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
128       GVSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
129     else
130       GVSym = getSymbolPreferLocal(*GV);
131 
132     // Handle dllimport linkage.
133     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
134       GVSym = OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
135     else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
136       GVSym =
137           OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
138 
139     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
140         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
141       MCSymbol *Sym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
142       MachineModuleInfoImpl::StubValueTy &StubSym =
143           MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
144       if (!StubSym.getPointer())
145         StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
146                                                      !GV->hasInternalLinkage());
147     }
148 
149     // If the name begins with a dollar-sign, enclose it in parens.  We do this
150     // to avoid having it look like an integer immediate to the assembler.
151     if (GVSym->getName()[0] != '$')
152       GVSym->print(O, MAI);
153     else {
154       O << '(';
155       GVSym->print(O, MAI);
156       O << ')';
157     }
158     printOffset(MO.getOffset(), O);
159     break;
160   }
161   }
162 
163   switch (MO.getTargetFlags()) {
164   default:
165     llvm_unreachable("Unknown target flag on GV operand");
166   case X86II::MO_NO_FLAG:    // No flag.
167     break;
168   case X86II::MO_DARWIN_NONLAZY:
169   case X86II::MO_DLLIMPORT:
170   case X86II::MO_COFFSTUB:
171     // These affect the name of the symbol, not any suffix.
172     break;
173   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
174     O << " + [.-";
175     MF->getPICBaseSymbol()->print(O, MAI);
176     O << ']';
177     break;
178   case X86II::MO_PIC_BASE_OFFSET:
179   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
180     O << '-';
181     MF->getPICBaseSymbol()->print(O, MAI);
182     break;
183   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
184   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
185   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
186   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
187   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
188   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
189   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
190   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
191   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
192   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
193   case X86II::MO_GOTPCREL_NORELAX: O << "@GOTPCREL_NORELAX"; break;
194   case X86II::MO_GOT:       O << "@GOT";       break;
195   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
196   case X86II::MO_PLT:       O << "@PLT";       break;
197   case X86II::MO_TLVP:      O << "@TLVP";      break;
198   case X86II::MO_TLVP_PIC_BASE:
199     O << "@TLVP" << '-';
200     MF->getPICBaseSymbol()->print(O, MAI);
201     break;
202   case X86II::MO_SECREL:    O << "@SECREL32";  break;
203   }
204 }
205 
PrintOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)206 void X86AsmPrinter::PrintOperand(const MachineInstr *MI, unsigned OpNo,
207                                  raw_ostream &O) {
208   const MachineOperand &MO = MI->getOperand(OpNo);
209   const bool IsATT = MI->getInlineAsmDialect() == InlineAsm::AD_ATT;
210   switch (MO.getType()) {
211   default: llvm_unreachable("unknown operand type!");
212   case MachineOperand::MO_Register: {
213     if (IsATT)
214       O << '%';
215     O << X86ATTInstPrinter::getRegisterName(MO.getReg());
216     return;
217   }
218 
219   case MachineOperand::MO_Immediate:
220     if (IsATT)
221       O << '$';
222     O << MO.getImm();
223     return;
224 
225   case MachineOperand::MO_ConstantPoolIndex:
226   case MachineOperand::MO_GlobalAddress: {
227     switch (MI->getInlineAsmDialect()) {
228     case InlineAsm::AD_ATT:
229       O << '$';
230       break;
231     case InlineAsm::AD_Intel:
232       O << "offset ";
233       break;
234     }
235     PrintSymbolOperand(MO, O);
236     break;
237   }
238   case MachineOperand::MO_BlockAddress: {
239     MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
240     Sym->print(O, MAI);
241     break;
242   }
243   }
244 }
245 
246 /// PrintModifiedOperand - Print subregisters based on supplied modifier,
247 /// deferring to PrintOperand() if no modifier was supplied or if operand is not
248 /// a register.
PrintModifiedOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)249 void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
250                                          raw_ostream &O, const char *Modifier) {
251   const MachineOperand &MO = MI->getOperand(OpNo);
252   if (!Modifier || !MO.isReg())
253     return PrintOperand(MI, OpNo, O);
254   if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
255     O << '%';
256   Register Reg = MO.getReg();
257   if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
258     unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
259         (strcmp(Modifier+6,"32") == 0) ? 32 :
260         (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
261     Reg = getX86SubSuperRegister(Reg, Size);
262   }
263   O << X86ATTInstPrinter::getRegisterName(Reg);
264 }
265 
266 /// PrintPCRelImm - This is used to print an immediate value that ends up
267 /// being encoded as a pc-relative value.  These print slightly differently, for
268 /// example, a $ is not emitted.
PrintPCRelImm(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)269 void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
270                                   raw_ostream &O) {
271   const MachineOperand &MO = MI->getOperand(OpNo);
272   switch (MO.getType()) {
273   default: llvm_unreachable("Unknown pcrel immediate operand");
274   case MachineOperand::MO_Register:
275     // pc-relativeness was handled when computing the value in the reg.
276     PrintOperand(MI, OpNo, O);
277     return;
278   case MachineOperand::MO_Immediate:
279     O << MO.getImm();
280     return;
281   case MachineOperand::MO_GlobalAddress:
282     PrintSymbolOperand(MO, O);
283     return;
284   }
285 }
286 
PrintLeaMemReference(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)287 void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
288                                          raw_ostream &O, const char *Modifier) {
289   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
290   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
291   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
292 
293   // If we really don't want to print out (rip), don't.
294   bool HasBaseReg = BaseReg.getReg() != 0;
295   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
296       BaseReg.getReg() == X86::RIP)
297     HasBaseReg = false;
298 
299   // HasParenPart - True if we will print out the () part of the mem ref.
300   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
301 
302   switch (DispSpec.getType()) {
303   default:
304     llvm_unreachable("unknown operand type!");
305   case MachineOperand::MO_Immediate: {
306     int DispVal = DispSpec.getImm();
307     if (DispVal || !HasParenPart)
308       O << DispVal;
309     break;
310   }
311   case MachineOperand::MO_GlobalAddress:
312   case MachineOperand::MO_ConstantPoolIndex:
313     PrintSymbolOperand(DispSpec, O);
314     break;
315   }
316 
317   if (Modifier && strcmp(Modifier, "H") == 0)
318     O << "+8";
319 
320   if (HasParenPart) {
321     assert(IndexReg.getReg() != X86::ESP &&
322            "X86 doesn't allow scaling by ESP");
323 
324     O << '(';
325     if (HasBaseReg)
326       PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
327 
328     if (IndexReg.getReg()) {
329       O << ',';
330       PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
331       unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
332       if (ScaleVal != 1)
333         O << ',' << ScaleVal;
334     }
335     O << ')';
336   }
337 }
338 
isSimpleReturn(const MachineInstr & MI)339 static bool isSimpleReturn(const MachineInstr &MI) {
340   // We exclude all tail calls here which set both isReturn and isCall.
341   return MI.getDesc().isReturn() && !MI.getDesc().isCall();
342 }
343 
isIndirectBranchOrTailCall(const MachineInstr & MI)344 static bool isIndirectBranchOrTailCall(const MachineInstr &MI) {
345   unsigned Opc = MI.getOpcode();
346   return MI.getDesc().isIndirectBranch() /*Make below code in a good shape*/ ||
347          Opc == X86::TAILJMPr || Opc == X86::TAILJMPm ||
348          Opc == X86::TAILJMPr64 || Opc == X86::TAILJMPm64 ||
349          Opc == X86::TCRETURNri || Opc == X86::TCRETURNmi ||
350          Opc == X86::TCRETURNri64 || Opc == X86::TCRETURNmi64 ||
351          Opc == X86::TAILJMPr64_REX || Opc == X86::TAILJMPm64_REX;
352 }
353 
emitBasicBlockEnd(const MachineBasicBlock & MBB)354 void X86AsmPrinter::emitBasicBlockEnd(const MachineBasicBlock &MBB) {
355   if (Subtarget->hardenSlsRet() || Subtarget->hardenSlsIJmp()) {
356     auto I = MBB.getLastNonDebugInstr();
357     if (I != MBB.end()) {
358       if ((Subtarget->hardenSlsRet() && isSimpleReturn(*I)) ||
359           (Subtarget->hardenSlsIJmp() && isIndirectBranchOrTailCall(*I))) {
360         MCInst TmpInst;
361         TmpInst.setOpcode(X86::INT3);
362         EmitToStreamer(*OutStreamer, TmpInst);
363       }
364     }
365   }
366   AsmPrinter::emitBasicBlockEnd(MBB);
367   SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
368 }
369 
PrintMemReference(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)370 void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
371                                       raw_ostream &O, const char *Modifier) {
372   assert(isMem(*MI, OpNo) && "Invalid memory reference!");
373   const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
374   if (Segment.getReg()) {
375     PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
376     O << ':';
377   }
378   PrintLeaMemReference(MI, OpNo, O, Modifier);
379 }
380 
381 
PrintIntelMemReference(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)382 void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
383                                            unsigned OpNo, raw_ostream &O,
384                                            const char *Modifier) {
385   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
386   unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
387   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
388   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
389   const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
390 
391   // If we really don't want to print out (rip), don't.
392   bool HasBaseReg = BaseReg.getReg() != 0;
393   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
394       BaseReg.getReg() == X86::RIP)
395     HasBaseReg = false;
396 
397   // If we really just want to print out displacement.
398   if (Modifier && (DispSpec.isGlobal() || DispSpec.isSymbol()) &&
399       !strcmp(Modifier, "disp-only")) {
400     HasBaseReg = false;
401   }
402 
403   // If this has a segment register, print it.
404   if (SegReg.getReg()) {
405     PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
406     O << ':';
407   }
408 
409   O << '[';
410 
411   bool NeedPlus = false;
412   if (HasBaseReg) {
413     PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
414     NeedPlus = true;
415   }
416 
417   if (IndexReg.getReg()) {
418     if (NeedPlus) O << " + ";
419     if (ScaleVal != 1)
420       O << ScaleVal << '*';
421     PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
422     NeedPlus = true;
423   }
424 
425   if (!DispSpec.isImm()) {
426     if (NeedPlus) O << " + ";
427     PrintOperand(MI, OpNo + X86::AddrDisp, O);
428   } else {
429     int64_t DispVal = DispSpec.getImm();
430     if (DispVal || (!IndexReg.getReg() && !HasBaseReg)) {
431       if (NeedPlus) {
432         if (DispVal > 0)
433           O << " + ";
434         else {
435           O << " - ";
436           DispVal = -DispVal;
437         }
438       }
439       O << DispVal;
440     }
441   }
442   O << ']';
443 }
444 
printAsmMRegister(const X86AsmPrinter & P,const MachineOperand & MO,char Mode,raw_ostream & O)445 static bool printAsmMRegister(const X86AsmPrinter &P, const MachineOperand &MO,
446                               char Mode, raw_ostream &O) {
447   Register Reg = MO.getReg();
448   bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
449 
450   if (!X86::GR8RegClass.contains(Reg) &&
451       !X86::GR16RegClass.contains(Reg) &&
452       !X86::GR32RegClass.contains(Reg) &&
453       !X86::GR64RegClass.contains(Reg))
454     return true;
455 
456   switch (Mode) {
457   default: return true;  // Unknown mode.
458   case 'b': // Print QImode register
459     Reg = getX86SubSuperRegister(Reg, 8);
460     break;
461   case 'h': // Print QImode high register
462     Reg = getX86SubSuperRegister(Reg, 8, true);
463     break;
464   case 'w': // Print HImode register
465     Reg = getX86SubSuperRegister(Reg, 16);
466     break;
467   case 'k': // Print SImode register
468     Reg = getX86SubSuperRegister(Reg, 32);
469     break;
470   case 'V':
471     EmitPercent = false;
472     LLVM_FALLTHROUGH;
473   case 'q':
474     // Print 64-bit register names if 64-bit integer registers are available.
475     // Otherwise, print 32-bit register names.
476     Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
477     break;
478   }
479 
480   if (EmitPercent)
481     O << '%';
482 
483   O << X86ATTInstPrinter::getRegisterName(Reg);
484   return false;
485 }
486 
printAsmVRegister(const MachineOperand & MO,char Mode,raw_ostream & O)487 static bool printAsmVRegister(const MachineOperand &MO, char Mode,
488                               raw_ostream &O) {
489   Register Reg = MO.getReg();
490   bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
491 
492   unsigned Index;
493   if (X86::VR128XRegClass.contains(Reg))
494     Index = Reg - X86::XMM0;
495   else if (X86::VR256XRegClass.contains(Reg))
496     Index = Reg - X86::YMM0;
497   else if (X86::VR512RegClass.contains(Reg))
498     Index = Reg - X86::ZMM0;
499   else
500     return true;
501 
502   switch (Mode) {
503   default: // Unknown mode.
504     return true;
505   case 'x': // Print V4SFmode register
506     Reg = X86::XMM0 + Index;
507     break;
508   case 't': // Print V8SFmode register
509     Reg = X86::YMM0 + Index;
510     break;
511   case 'g': // Print V16SFmode register
512     Reg = X86::ZMM0 + Index;
513     break;
514   }
515 
516   if (EmitPercent)
517     O << '%';
518 
519   O << X86ATTInstPrinter::getRegisterName(Reg);
520   return false;
521 }
522 
523 /// PrintAsmOperand - Print out an operand for an inline asm expression.
524 ///
PrintAsmOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & O)525 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
526                                     const char *ExtraCode, raw_ostream &O) {
527   // Does this asm operand have a single letter operand modifier?
528   if (ExtraCode && ExtraCode[0]) {
529     if (ExtraCode[1] != 0) return true; // Unknown modifier.
530 
531     const MachineOperand &MO = MI->getOperand(OpNo);
532 
533     switch (ExtraCode[0]) {
534     default:
535       // See if this is a generic print operand
536       return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
537     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
538       switch (MO.getType()) {
539       default:
540         return true;
541       case MachineOperand::MO_Immediate:
542         O << MO.getImm();
543         return false;
544       case MachineOperand::MO_ConstantPoolIndex:
545       case MachineOperand::MO_JumpTableIndex:
546       case MachineOperand::MO_ExternalSymbol:
547         llvm_unreachable("unexpected operand type!");
548       case MachineOperand::MO_GlobalAddress:
549         PrintSymbolOperand(MO, O);
550         if (Subtarget->isPICStyleRIPRel())
551           O << "(%rip)";
552         return false;
553       case MachineOperand::MO_Register:
554         O << '(';
555         PrintOperand(MI, OpNo, O);
556         O << ')';
557         return false;
558       }
559 
560     case 'c': // Don't print "$" before a global var name or constant.
561       switch (MO.getType()) {
562       default:
563         PrintOperand(MI, OpNo, O);
564         break;
565       case MachineOperand::MO_Immediate:
566         O << MO.getImm();
567         break;
568       case MachineOperand::MO_ConstantPoolIndex:
569       case MachineOperand::MO_JumpTableIndex:
570       case MachineOperand::MO_ExternalSymbol:
571         llvm_unreachable("unexpected operand type!");
572       case MachineOperand::MO_GlobalAddress:
573         PrintSymbolOperand(MO, O);
574         break;
575       }
576       return false;
577 
578     case 'A': // Print '*' before a register (it must be a register)
579       if (MO.isReg()) {
580         O << '*';
581         PrintOperand(MI, OpNo, O);
582         return false;
583       }
584       return true;
585 
586     case 'b': // Print QImode register
587     case 'h': // Print QImode high register
588     case 'w': // Print HImode register
589     case 'k': // Print SImode register
590     case 'q': // Print DImode register
591     case 'V': // Print native register without '%'
592       if (MO.isReg())
593         return printAsmMRegister(*this, MO, ExtraCode[0], O);
594       PrintOperand(MI, OpNo, O);
595       return false;
596 
597     case 'x': // Print V4SFmode register
598     case 't': // Print V8SFmode register
599     case 'g': // Print V16SFmode register
600       if (MO.isReg())
601         return printAsmVRegister(MO, ExtraCode[0], O);
602       PrintOperand(MI, OpNo, O);
603       return false;
604 
605     case 'P': // This is the operand of a call, treat specially.
606       PrintPCRelImm(MI, OpNo, O);
607       return false;
608 
609     case 'n': // Negate the immediate or print a '-' before the operand.
610       // Note: this is a temporary solution. It should be handled target
611       // independently as part of the 'MC' work.
612       if (MO.isImm()) {
613         O << -MO.getImm();
614         return false;
615       }
616       O << '-';
617     }
618   }
619 
620   PrintOperand(MI, OpNo, O);
621   return false;
622 }
623 
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & O)624 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
625                                           const char *ExtraCode,
626                                           raw_ostream &O) {
627   if (ExtraCode && ExtraCode[0]) {
628     if (ExtraCode[1] != 0) return true; // Unknown modifier.
629 
630     switch (ExtraCode[0]) {
631     default: return true;  // Unknown modifier.
632     case 'b': // Print QImode register
633     case 'h': // Print QImode high register
634     case 'w': // Print HImode register
635     case 'k': // Print SImode register
636     case 'q': // Print SImode register
637       // These only apply to registers, ignore on mem.
638       break;
639     case 'H':
640       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
641         return true;  // Unsupported modifier in Intel inline assembly.
642       } else {
643         PrintMemReference(MI, OpNo, O, "H");
644       }
645       return false;
646    // Print memory only with displacement. The Modifer 'P' is used in inline
647    // asm to present a call symbol or a global symbol which can not use base
648    // reg or index reg.
649     case 'P':
650       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
651         PrintIntelMemReference(MI, OpNo, O, "disp-only");
652       } else {
653         PrintMemReference(MI, OpNo, O, "disp-only");
654       }
655       return false;
656     }
657   }
658   if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
659     PrintIntelMemReference(MI, OpNo, O, nullptr);
660   } else {
661     PrintMemReference(MI, OpNo, O, nullptr);
662   }
663   return false;
664 }
665 
emitStartOfAsmFile(Module & M)666 void X86AsmPrinter::emitStartOfAsmFile(Module &M) {
667   const Triple &TT = TM.getTargetTriple();
668 
669   if (TT.isOSBinFormatELF()) {
670     // Assemble feature flags that may require creation of a note section.
671     unsigned FeatureFlagsAnd = 0;
672     if (M.getModuleFlag("cf-protection-branch"))
673       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
674     if (M.getModuleFlag("cf-protection-return"))
675       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
676 
677     if (FeatureFlagsAnd) {
678       // Emit a .note.gnu.property section with the flags.
679       if (!TT.isArch32Bit() && !TT.isArch64Bit())
680         llvm_unreachable("CFProtection used on invalid architecture!");
681       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
682       MCSection *Nt = MMI->getContext().getELFSection(
683           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
684       OutStreamer->switchSection(Nt);
685 
686       // Emitting note header.
687       const int WordSize = TT.isArch64Bit() && !TT.isX32() ? 8 : 4;
688       emitAlignment(WordSize == 4 ? Align(4) : Align(8));
689       OutStreamer->emitIntValue(4, 4 /*size*/); // data size for "GNU\0"
690       OutStreamer->emitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
691       OutStreamer->emitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
692       OutStreamer->emitBytes(StringRef("GNU", 4)); // note name
693 
694       // Emitting an Elf_Prop for the CET properties.
695       OutStreamer->emitInt32(ELF::GNU_PROPERTY_X86_FEATURE_1_AND);
696       OutStreamer->emitInt32(4);                          // data size
697       OutStreamer->emitInt32(FeatureFlagsAnd);            // data
698       emitAlignment(WordSize == 4 ? Align(4) : Align(8)); // padding
699 
700       OutStreamer->endSection(Nt);
701       OutStreamer->switchSection(Cur);
702     }
703   }
704 
705   if (TT.isOSBinFormatMachO())
706     OutStreamer->switchSection(getObjFileLowering().getTextSection());
707 
708   if (TT.isOSBinFormatCOFF()) {
709     // Emit an absolute @feat.00 symbol.  This appears to be some kind of
710     // compiler features bitfield read by link.exe.
711     MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
712     OutStreamer->beginCOFFSymbolDef(S);
713     OutStreamer->emitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
714     OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
715     OutStreamer->endCOFFSymbolDef();
716     int64_t Feat00Flags = 0;
717 
718     if (TT.getArch() == Triple::x86) {
719       // According to the PE-COFF spec, the LSB of this value marks the object
720       // for "registered SEH".  This means that all SEH handler entry points
721       // must be registered in .sxdata.  Use of any unregistered handlers will
722       // cause the process to terminate immediately.  LLVM does not know how to
723       // register any SEH handlers, so its object files should be safe.
724       Feat00Flags |= 1;
725     }
726 
727     if (M.getModuleFlag("cfguard")) {
728       Feat00Flags |= 0x800; // Object is CFG-aware.
729     }
730 
731     if (M.getModuleFlag("ehcontguard")) {
732       Feat00Flags |= 0x4000; // Object also has EHCont.
733     }
734 
735     OutStreamer->emitSymbolAttribute(S, MCSA_Global);
736     OutStreamer->emitAssignment(
737         S, MCConstantExpr::create(Feat00Flags, MMI->getContext()));
738   }
739   OutStreamer->emitSyntaxDirective();
740 
741   // If this is not inline asm and we're in 16-bit
742   // mode prefix assembly with .code16.
743   bool is16 = TT.getEnvironment() == Triple::CODE16;
744   if (M.getModuleInlineAsm().empty() && is16)
745     OutStreamer->emitAssemblerFlag(MCAF_Code16);
746 }
747 
748 static void
emitNonLazySymbolPointer(MCStreamer & OutStreamer,MCSymbol * StubLabel,MachineModuleInfoImpl::StubValueTy & MCSym)749 emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
750                          MachineModuleInfoImpl::StubValueTy &MCSym) {
751   // L_foo$stub:
752   OutStreamer.emitLabel(StubLabel);
753   //   .indirect_symbol _foo
754   OutStreamer.emitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
755 
756   if (MCSym.getInt())
757     // External to current translation unit.
758     OutStreamer.emitIntValue(0, 4/*size*/);
759   else
760     // Internal to current translation unit.
761     //
762     // When we place the LSDA into the TEXT section, the type info
763     // pointers need to be indirect and pc-rel. We accomplish this by
764     // using NLPs; however, sometimes the types are local to the file.
765     // We need to fill in the value for the NLP in those cases.
766     OutStreamer.emitValue(
767         MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
768         4 /*size*/);
769 }
770 
emitNonLazyStubs(MachineModuleInfo * MMI,MCStreamer & OutStreamer)771 static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
772 
773   MachineModuleInfoMachO &MMIMacho =
774       MMI->getObjFileInfo<MachineModuleInfoMachO>();
775 
776   // Output stubs for dynamically-linked functions.
777   MachineModuleInfoMachO::SymbolListTy Stubs;
778 
779   // Output stubs for external and common global variables.
780   Stubs = MMIMacho.GetGVStubList();
781   if (!Stubs.empty()) {
782     OutStreamer.switchSection(MMI->getContext().getMachOSection(
783         "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
784         SectionKind::getMetadata()));
785 
786     for (auto &Stub : Stubs)
787       emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
788 
789     Stubs.clear();
790     OutStreamer.addBlankLine();
791   }
792 }
793 
emitEndOfAsmFile(Module & M)794 void X86AsmPrinter::emitEndOfAsmFile(Module &M) {
795   const Triple &TT = TM.getTargetTriple();
796 
797   if (TT.isOSBinFormatMachO()) {
798     // Mach-O uses non-lazy symbol stubs to encode per-TU information into
799     // global table for symbol lookup.
800     emitNonLazyStubs(MMI, *OutStreamer);
801 
802     // Emit stack and fault map information.
803     emitStackMaps(SM);
804     FM.serializeToFaultMapSection();
805 
806     // This flag tells the linker that no global symbols contain code that fall
807     // through to other global symbols (e.g. an implementation of multiple entry
808     // points). If this doesn't occur, the linker can safely perform dead code
809     // stripping. Since LLVM never generates code that does this, it is always
810     // safe to set.
811     OutStreamer->emitAssemblerFlag(MCAF_SubsectionsViaSymbols);
812   } else if (TT.isOSBinFormatCOFF()) {
813     if (MMI->usesMSVCFloatingPoint()) {
814       // In Windows' libcmt.lib, there is a file which is linked in only if the
815       // symbol _fltused is referenced. Linking this in causes some
816       // side-effects:
817       //
818       // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
819       // 64-bit mantissas at program start.
820       //
821       // 2. It links in support routines for floating-point in scanf and printf.
822       //
823       // MSVC emits an undefined reference to _fltused when there are any
824       // floating point operations in the program (including calls). A program
825       // that only has: `scanf("%f", &global_float);` may fail to trigger this,
826       // but oh well...that's a documented issue.
827       StringRef SymbolName =
828           (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
829       MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
830       OutStreamer->emitSymbolAttribute(S, MCSA_Global);
831       return;
832     }
833     emitStackMaps(SM);
834   } else if (TT.isOSBinFormatELF()) {
835     emitStackMaps(SM);
836     FM.serializeToFaultMapSection();
837   }
838 
839   // Emit __morestack address if needed for indirect calls.
840   if (TT.getArch() == Triple::x86_64 && TM.getCodeModel() == CodeModel::Large) {
841     if (MCSymbol *AddrSymbol = OutContext.lookupSymbol("__morestack_addr")) {
842       Align Alignment(1);
843       MCSection *ReadOnlySection = getObjFileLowering().getSectionForConstant(
844           getDataLayout(), SectionKind::getReadOnly(),
845           /*C=*/nullptr, Alignment);
846       OutStreamer->switchSection(ReadOnlySection);
847       OutStreamer->emitLabel(AddrSymbol);
848 
849       unsigned PtrSize = MAI->getCodePointerSize();
850       OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("__morestack"),
851                                    PtrSize);
852     }
853   }
854 }
855 
856 //===----------------------------------------------------------------------===//
857 // Target Registry Stuff
858 //===----------------------------------------------------------------------===//
859 
860 // Force static initialization.
LLVMInitializeX86AsmPrinter()861 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeX86AsmPrinter() {
862   RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
863   RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
864 }
865