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/MachineValueType.h"
27 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
28 #include "llvm/IR/DerivedTypes.h"
29 #include "llvm/IR/InlineAsm.h"
30 #include "llvm/IR/Mangler.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/IR/Type.h"
33 #include "llvm/MC/MCAsmInfo.h"
34 #include "llvm/MC/MCCodeEmitter.h"
35 #include "llvm/MC/MCContext.h"
36 #include "llvm/MC/MCExpr.h"
37 #include "llvm/MC/MCInstBuilder.h"
38 #include "llvm/MC/MCSectionCOFF.h"
39 #include "llvm/MC/MCSectionELF.h"
40 #include "llvm/MC/MCSectionMachO.h"
41 #include "llvm/MC/MCStreamer.h"
42 #include "llvm/MC/MCSymbol.h"
43 #include "llvm/MC/TargetRegistry.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/Support/ErrorHandling.h"
46 #include "llvm/Target/TargetMachine.h"
47 
48 using namespace llvm;
49 
50 X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
51                              std::unique_ptr<MCStreamer> Streamer)
52     : AsmPrinter(TM, std::move(Streamer)), FM(*this) {}
53 
54 //===----------------------------------------------------------------------===//
55 // Primitive Helper Functions.
56 //===----------------------------------------------------------------------===//
57 
58 /// runOnMachineFunction - Emit the function body.
59 ///
60 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
61   Subtarget = &MF.getSubtarget<X86Subtarget>();
62 
63   SMShadowTracker.startFunction(MF);
64   CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
65       *Subtarget->getInstrInfo(), MF.getContext()));
66 
67   EmitFPOData =
68       Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
69 
70   IndCSPrefix =
71       MF.getMMI().getModule()->getModuleFlag("indirect_branch_cs_prefix");
72 
73   SetupMachineFunction(MF);
74 
75   if (Subtarget->isTargetCOFF()) {
76     bool Local = MF.getFunction().hasLocalLinkage();
77     OutStreamer->beginCOFFSymbolDef(CurrentFnSym);
78     OutStreamer->emitCOFFSymbolStorageClass(
79         Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
80     OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
81                                     << COFF::SCT_COMPLEX_TYPE_SHIFT);
82     OutStreamer->endCOFFSymbolDef();
83   }
84 
85   // Emit the rest of the function body.
86   emitFunctionBody();
87 
88   // Emit the XRay table for this function.
89   emitXRayTable();
90 
91   EmitFPOData = false;
92 
93   IndCSPrefix = false;
94 
95   // We didn't modify anything.
96   return false;
97 }
98 
99 void X86AsmPrinter::emitFunctionBodyStart() {
100   if (EmitFPOData) {
101     auto *XTS =
102         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
103     XTS->emitFPOProc(
104         CurrentFnSym,
105         MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
106   }
107 }
108 
109 void X86AsmPrinter::emitFunctionBodyEnd() {
110   if (EmitFPOData) {
111     auto *XTS =
112         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
113     XTS->emitFPOEndProc();
114   }
115 }
116 
117 uint32_t X86AsmPrinter::MaskKCFIType(uint32_t Value) {
118   // If the type hash matches an invalid pattern, mask the value.
119   const uint32_t InvalidValues[] = {
120       0xFA1E0FF3, /* ENDBR64 */
121       0xFB1E0FF3, /* ENDBR32 */
122   };
123   for (uint32_t N : InvalidValues) {
124     // LowerKCFI_CHECK emits -Value for indirect call checks, so we must also
125     // mask that. Note that -(Value + 1) == ~Value.
126     if (N == Value || -N == Value)
127       return Value + 1;
128   }
129   return Value;
130 }
131 
132 void X86AsmPrinter::EmitKCFITypePadding(const MachineFunction &MF,
133                                         bool HasType) {
134   // Keep the function entry aligned, taking patchable-function-prefix into
135   // account if set.
136   int64_t PrefixBytes = 0;
137   (void)MF.getFunction()
138       .getFnAttribute("patchable-function-prefix")
139       .getValueAsString()
140       .getAsInteger(10, PrefixBytes);
141 
142   // Also take the type identifier into account if we're emitting
143   // one. Otherwise, just pad with nops. The X86::MOV32ri instruction emitted
144   // in X86AsmPrinter::emitKCFITypeId is 5 bytes long.
145   if (HasType)
146     PrefixBytes += 5;
147 
148   emitNops(offsetToAlignment(PrefixBytes, MF.getAlignment()));
149 }
150 
151 /// emitKCFITypeId - Emit the KCFI type information in architecture specific
152 /// format.
153 void X86AsmPrinter::emitKCFITypeId(const MachineFunction &MF) {
154   const Function &F = MF.getFunction();
155   if (!F.getParent()->getModuleFlag("kcfi"))
156     return;
157 
158   ConstantInt *Type = nullptr;
159   if (const MDNode *MD = F.getMetadata(LLVMContext::MD_kcfi_type))
160     Type = mdconst::extract<ConstantInt>(MD->getOperand(0));
161 
162   // If we don't have a type to emit, just emit padding if needed to maintain
163   // the same alignment for all functions.
164   if (!Type) {
165     EmitKCFITypePadding(MF, /*HasType=*/false);
166     return;
167   }
168 
169   // Emit a function symbol for the type data to avoid unreachable instruction
170   // warnings from binary validation tools, and use the same linkage as the
171   // parent function. Note that using local linkage would result in duplicate
172   // symbols for weak parent functions.
173   MCSymbol *FnSym = OutContext.getOrCreateSymbol("__cfi_" + MF.getName());
174   emitLinkage(&MF.getFunction(), FnSym);
175   if (MAI->hasDotTypeDotSizeDirective())
176     OutStreamer->emitSymbolAttribute(FnSym, MCSA_ELF_TypeFunction);
177   OutStreamer->emitLabel(FnSym);
178 
179   // Embed the type hash in the X86::MOV32ri instruction to avoid special
180   // casing object file parsers.
181   EmitKCFITypePadding(MF);
182   EmitAndCountInstruction(MCInstBuilder(X86::MOV32ri)
183                               .addReg(X86::EAX)
184                               .addImm(MaskKCFIType(Type->getZExtValue())));
185 
186   if (MAI->hasDotTypeDotSizeDirective()) {
187     MCSymbol *EndSym = OutContext.createTempSymbol("cfi_func_end");
188     OutStreamer->emitLabel(EndSym);
189 
190     const MCExpr *SizeExp = MCBinaryExpr::createSub(
191         MCSymbolRefExpr::create(EndSym, OutContext),
192         MCSymbolRefExpr::create(FnSym, OutContext), OutContext);
193     OutStreamer->emitELFSize(FnSym, SizeExp);
194   }
195 }
196 
197 /// PrintSymbolOperand - Print a raw symbol reference operand.  This handles
198 /// jump tables, constant pools, global address and external symbols, all of
199 /// which print to a label with various suffixes for relocation types etc.
200 void X86AsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
201                                        raw_ostream &O) {
202   switch (MO.getType()) {
203   default: llvm_unreachable("unknown symbol type!");
204   case MachineOperand::MO_ConstantPoolIndex:
205     GetCPISymbol(MO.getIndex())->print(O, MAI);
206     printOffset(MO.getOffset(), O);
207     break;
208   case MachineOperand::MO_GlobalAddress: {
209     const GlobalValue *GV = MO.getGlobal();
210 
211     MCSymbol *GVSym;
212     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
213         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
214       GVSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
215     else
216       GVSym = getSymbolPreferLocal(*GV);
217 
218     // Handle dllimport linkage.
219     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
220       GVSym = OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
221     else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
222       GVSym =
223           OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
224 
225     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
226         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
227       MCSymbol *Sym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
228       MachineModuleInfoImpl::StubValueTy &StubSym =
229           MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
230       if (!StubSym.getPointer())
231         StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
232                                                      !GV->hasInternalLinkage());
233     }
234 
235     // If the name begins with a dollar-sign, enclose it in parens.  We do this
236     // to avoid having it look like an integer immediate to the assembler.
237     if (GVSym->getName()[0] != '$')
238       GVSym->print(O, MAI);
239     else {
240       O << '(';
241       GVSym->print(O, MAI);
242       O << ')';
243     }
244     printOffset(MO.getOffset(), O);
245     break;
246   }
247   }
248 
249   switch (MO.getTargetFlags()) {
250   default:
251     llvm_unreachable("Unknown target flag on GV operand");
252   case X86II::MO_NO_FLAG:    // No flag.
253     break;
254   case X86II::MO_DARWIN_NONLAZY:
255   case X86II::MO_DLLIMPORT:
256   case X86II::MO_COFFSTUB:
257     // These affect the name of the symbol, not any suffix.
258     break;
259   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
260     O << " + [.-";
261     MF->getPICBaseSymbol()->print(O, MAI);
262     O << ']';
263     break;
264   case X86II::MO_PIC_BASE_OFFSET:
265   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
266     O << '-';
267     MF->getPICBaseSymbol()->print(O, MAI);
268     break;
269   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
270   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
271   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
272   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
273   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
274   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
275   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
276   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
277   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
278   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
279   case X86II::MO_GOTPCREL_NORELAX: O << "@GOTPCREL_NORELAX"; break;
280   case X86II::MO_GOT:       O << "@GOT";       break;
281   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
282   case X86II::MO_PLT:       O << "@PLT";       break;
283   case X86II::MO_TLVP:      O << "@TLVP";      break;
284   case X86II::MO_TLVP_PIC_BASE:
285     O << "@TLVP" << '-';
286     MF->getPICBaseSymbol()->print(O, MAI);
287     break;
288   case X86II::MO_SECREL:    O << "@SECREL32";  break;
289   }
290 }
291 
292 void X86AsmPrinter::PrintOperand(const MachineInstr *MI, unsigned OpNo,
293                                  raw_ostream &O) {
294   const MachineOperand &MO = MI->getOperand(OpNo);
295   const bool IsATT = MI->getInlineAsmDialect() == InlineAsm::AD_ATT;
296   switch (MO.getType()) {
297   default: llvm_unreachable("unknown operand type!");
298   case MachineOperand::MO_Register: {
299     if (IsATT)
300       O << '%';
301     O << X86ATTInstPrinter::getRegisterName(MO.getReg());
302     return;
303   }
304 
305   case MachineOperand::MO_Immediate:
306     if (IsATT)
307       O << '$';
308     O << MO.getImm();
309     return;
310 
311   case MachineOperand::MO_ConstantPoolIndex:
312   case MachineOperand::MO_GlobalAddress: {
313     switch (MI->getInlineAsmDialect()) {
314     case InlineAsm::AD_ATT:
315       O << '$';
316       break;
317     case InlineAsm::AD_Intel:
318       O << "offset ";
319       break;
320     }
321     PrintSymbolOperand(MO, O);
322     break;
323   }
324   case MachineOperand::MO_BlockAddress: {
325     MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
326     Sym->print(O, MAI);
327     break;
328   }
329   }
330 }
331 
332 /// PrintModifiedOperand - Print subregisters based on supplied modifier,
333 /// deferring to PrintOperand() if no modifier was supplied or if operand is not
334 /// a register.
335 void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
336                                          raw_ostream &O, const char *Modifier) {
337   const MachineOperand &MO = MI->getOperand(OpNo);
338   if (!Modifier || !MO.isReg())
339     return PrintOperand(MI, OpNo, O);
340   if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
341     O << '%';
342   Register Reg = MO.getReg();
343   if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
344     unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
345         (strcmp(Modifier+6,"32") == 0) ? 32 :
346         (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
347     Reg = getX86SubSuperRegister(Reg, Size);
348   }
349   O << X86ATTInstPrinter::getRegisterName(Reg);
350 }
351 
352 /// PrintPCRelImm - This is used to print an immediate value that ends up
353 /// being encoded as a pc-relative value.  These print slightly differently, for
354 /// example, a $ is not emitted.
355 void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
356                                   raw_ostream &O) {
357   const MachineOperand &MO = MI->getOperand(OpNo);
358   switch (MO.getType()) {
359   default: llvm_unreachable("Unknown pcrel immediate operand");
360   case MachineOperand::MO_Register:
361     // pc-relativeness was handled when computing the value in the reg.
362     PrintOperand(MI, OpNo, O);
363     return;
364   case MachineOperand::MO_Immediate:
365     O << MO.getImm();
366     return;
367   case MachineOperand::MO_GlobalAddress:
368     PrintSymbolOperand(MO, O);
369     return;
370   }
371 }
372 
373 void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
374                                          raw_ostream &O, const char *Modifier) {
375   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
376   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
377   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
378 
379   // If we really don't want to print out (rip), don't.
380   bool HasBaseReg = BaseReg.getReg() != 0;
381   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
382       BaseReg.getReg() == X86::RIP)
383     HasBaseReg = false;
384 
385   // HasParenPart - True if we will print out the () part of the mem ref.
386   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
387 
388   switch (DispSpec.getType()) {
389   default:
390     llvm_unreachable("unknown operand type!");
391   case MachineOperand::MO_Immediate: {
392     int DispVal = DispSpec.getImm();
393     if (DispVal || !HasParenPart)
394       O << DispVal;
395     break;
396   }
397   case MachineOperand::MO_GlobalAddress:
398   case MachineOperand::MO_ConstantPoolIndex:
399     PrintSymbolOperand(DispSpec, O);
400     break;
401   }
402 
403   if (Modifier && strcmp(Modifier, "H") == 0)
404     O << "+8";
405 
406   if (HasParenPart) {
407     assert(IndexReg.getReg() != X86::ESP &&
408            "X86 doesn't allow scaling by ESP");
409 
410     O << '(';
411     if (HasBaseReg)
412       PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
413 
414     if (IndexReg.getReg()) {
415       O << ',';
416       PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
417       unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
418       if (ScaleVal != 1)
419         O << ',' << ScaleVal;
420     }
421     O << ')';
422   }
423 }
424 
425 static bool isSimpleReturn(const MachineInstr &MI) {
426   // We exclude all tail calls here which set both isReturn and isCall.
427   return MI.getDesc().isReturn() && !MI.getDesc().isCall();
428 }
429 
430 static bool isIndirectBranchOrTailCall(const MachineInstr &MI) {
431   unsigned Opc = MI.getOpcode();
432   return MI.getDesc().isIndirectBranch() /*Make below code in a good shape*/ ||
433          Opc == X86::TAILJMPr || Opc == X86::TAILJMPm ||
434          Opc == X86::TAILJMPr64 || Opc == X86::TAILJMPm64 ||
435          Opc == X86::TCRETURNri || Opc == X86::TCRETURNmi ||
436          Opc == X86::TCRETURNri64 || Opc == X86::TCRETURNmi64 ||
437          Opc == X86::TAILJMPr64_REX || Opc == X86::TAILJMPm64_REX;
438 }
439 
440 void X86AsmPrinter::emitBasicBlockEnd(const MachineBasicBlock &MBB) {
441   if (Subtarget->hardenSlsRet() || Subtarget->hardenSlsIJmp()) {
442     auto I = MBB.getLastNonDebugInstr();
443     if (I != MBB.end()) {
444       if ((Subtarget->hardenSlsRet() && isSimpleReturn(*I)) ||
445           (Subtarget->hardenSlsIJmp() && isIndirectBranchOrTailCall(*I))) {
446         MCInst TmpInst;
447         TmpInst.setOpcode(X86::INT3);
448         EmitToStreamer(*OutStreamer, TmpInst);
449       }
450     }
451   }
452   AsmPrinter::emitBasicBlockEnd(MBB);
453   SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
454 }
455 
456 void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
457                                       raw_ostream &O, const char *Modifier) {
458   assert(isMem(*MI, OpNo) && "Invalid memory reference!");
459   const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
460   if (Segment.getReg()) {
461     PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
462     O << ':';
463   }
464   PrintLeaMemReference(MI, OpNo, O, Modifier);
465 }
466 
467 
468 void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
469                                            unsigned OpNo, raw_ostream &O,
470                                            const char *Modifier) {
471   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
472   unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
473   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
474   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
475   const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
476 
477   // If we really don't want to print out (rip), don't.
478   bool HasBaseReg = BaseReg.getReg() != 0;
479   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
480       BaseReg.getReg() == X86::RIP)
481     HasBaseReg = false;
482 
483   // If we really just want to print out displacement.
484   if (Modifier && (DispSpec.isGlobal() || DispSpec.isSymbol()) &&
485       !strcmp(Modifier, "disp-only")) {
486     HasBaseReg = false;
487   }
488 
489   // If this has a segment register, print it.
490   if (SegReg.getReg()) {
491     PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
492     O << ':';
493   }
494 
495   O << '[';
496 
497   bool NeedPlus = false;
498   if (HasBaseReg) {
499     PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
500     NeedPlus = true;
501   }
502 
503   if (IndexReg.getReg()) {
504     if (NeedPlus) O << " + ";
505     if (ScaleVal != 1)
506       O << ScaleVal << '*';
507     PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
508     NeedPlus = true;
509   }
510 
511   if (!DispSpec.isImm()) {
512     if (NeedPlus) O << " + ";
513     // Do not add `offset` operator. Matches the behaviour of
514     // X86IntelInstPrinter::printMemReference.
515     PrintSymbolOperand(DispSpec, O);
516   } else {
517     int64_t DispVal = DispSpec.getImm();
518     if (DispVal || (!IndexReg.getReg() && !HasBaseReg)) {
519       if (NeedPlus) {
520         if (DispVal > 0)
521           O << " + ";
522         else {
523           O << " - ";
524           DispVal = -DispVal;
525         }
526       }
527       O << DispVal;
528     }
529   }
530   O << ']';
531 }
532 
533 static bool printAsmMRegister(const X86AsmPrinter &P, const MachineOperand &MO,
534                               char Mode, raw_ostream &O) {
535   Register Reg = MO.getReg();
536   bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
537 
538   if (!X86::GR8RegClass.contains(Reg) &&
539       !X86::GR16RegClass.contains(Reg) &&
540       !X86::GR32RegClass.contains(Reg) &&
541       !X86::GR64RegClass.contains(Reg))
542     return true;
543 
544   switch (Mode) {
545   default: return true;  // Unknown mode.
546   case 'b': // Print QImode register
547     Reg = getX86SubSuperRegister(Reg, 8);
548     break;
549   case 'h': // Print QImode high register
550     Reg = getX86SubSuperRegister(Reg, 8, true);
551     if (!Reg.isValid())
552       return true;
553     break;
554   case 'w': // Print HImode register
555     Reg = getX86SubSuperRegister(Reg, 16);
556     break;
557   case 'k': // Print SImode register
558     Reg = getX86SubSuperRegister(Reg, 32);
559     break;
560   case 'V':
561     EmitPercent = false;
562     [[fallthrough]];
563   case 'q':
564     // Print 64-bit register names if 64-bit integer registers are available.
565     // Otherwise, print 32-bit register names.
566     Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
567     break;
568   }
569 
570   if (EmitPercent)
571     O << '%';
572 
573   O << X86ATTInstPrinter::getRegisterName(Reg);
574   return false;
575 }
576 
577 static bool printAsmVRegister(const MachineOperand &MO, char Mode,
578                               raw_ostream &O) {
579   Register Reg = MO.getReg();
580   bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
581 
582   unsigned Index;
583   if (X86::VR128XRegClass.contains(Reg))
584     Index = Reg - X86::XMM0;
585   else if (X86::VR256XRegClass.contains(Reg))
586     Index = Reg - X86::YMM0;
587   else if (X86::VR512RegClass.contains(Reg))
588     Index = Reg - X86::ZMM0;
589   else
590     return true;
591 
592   switch (Mode) {
593   default: // Unknown mode.
594     return true;
595   case 'x': // Print V4SFmode register
596     Reg = X86::XMM0 + Index;
597     break;
598   case 't': // Print V8SFmode register
599     Reg = X86::YMM0 + Index;
600     break;
601   case 'g': // Print V16SFmode register
602     Reg = X86::ZMM0 + Index;
603     break;
604   }
605 
606   if (EmitPercent)
607     O << '%';
608 
609   O << X86ATTInstPrinter::getRegisterName(Reg);
610   return false;
611 }
612 
613 /// PrintAsmOperand - Print out an operand for an inline asm expression.
614 ///
615 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
616                                     const char *ExtraCode, raw_ostream &O) {
617   // Does this asm operand have a single letter operand modifier?
618   if (ExtraCode && ExtraCode[0]) {
619     if (ExtraCode[1] != 0) return true; // Unknown modifier.
620 
621     const MachineOperand &MO = MI->getOperand(OpNo);
622 
623     switch (ExtraCode[0]) {
624     default:
625       // See if this is a generic print operand
626       return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
627     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
628       switch (MO.getType()) {
629       default:
630         return true;
631       case MachineOperand::MO_Immediate:
632         O << MO.getImm();
633         return false;
634       case MachineOperand::MO_ConstantPoolIndex:
635       case MachineOperand::MO_JumpTableIndex:
636       case MachineOperand::MO_ExternalSymbol:
637         llvm_unreachable("unexpected operand type!");
638       case MachineOperand::MO_GlobalAddress:
639         PrintSymbolOperand(MO, O);
640         if (Subtarget->isPICStyleRIPRel())
641           O << "(%rip)";
642         return false;
643       case MachineOperand::MO_Register:
644         O << '(';
645         PrintOperand(MI, OpNo, O);
646         O << ')';
647         return false;
648       }
649 
650     case 'c': // Don't print "$" before a global var name or constant.
651       switch (MO.getType()) {
652       default:
653         PrintOperand(MI, OpNo, O);
654         break;
655       case MachineOperand::MO_Immediate:
656         O << MO.getImm();
657         break;
658       case MachineOperand::MO_ConstantPoolIndex:
659       case MachineOperand::MO_JumpTableIndex:
660       case MachineOperand::MO_ExternalSymbol:
661         llvm_unreachable("unexpected operand type!");
662       case MachineOperand::MO_GlobalAddress:
663         PrintSymbolOperand(MO, O);
664         break;
665       }
666       return false;
667 
668     case 'A': // Print '*' before a register (it must be a register)
669       if (MO.isReg()) {
670         O << '*';
671         PrintOperand(MI, OpNo, O);
672         return false;
673       }
674       return true;
675 
676     case 'b': // Print QImode register
677     case 'h': // Print QImode high register
678     case 'w': // Print HImode register
679     case 'k': // Print SImode register
680     case 'q': // Print DImode register
681     case 'V': // Print native register without '%'
682       if (MO.isReg())
683         return printAsmMRegister(*this, MO, ExtraCode[0], O);
684       PrintOperand(MI, OpNo, O);
685       return false;
686 
687     case 'x': // Print V4SFmode register
688     case 't': // Print V8SFmode register
689     case 'g': // Print V16SFmode register
690       if (MO.isReg())
691         return printAsmVRegister(MO, ExtraCode[0], O);
692       PrintOperand(MI, OpNo, O);
693       return false;
694 
695     case 'P': // This is the operand of a call, treat specially.
696       PrintPCRelImm(MI, OpNo, O);
697       return false;
698 
699     case 'n': // Negate the immediate or print a '-' before the operand.
700       // Note: this is a temporary solution. It should be handled target
701       // independently as part of the 'MC' work.
702       if (MO.isImm()) {
703         O << -MO.getImm();
704         return false;
705       }
706       O << '-';
707     }
708   }
709 
710   PrintOperand(MI, OpNo, O);
711   return false;
712 }
713 
714 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
715                                           const char *ExtraCode,
716                                           raw_ostream &O) {
717   if (ExtraCode && ExtraCode[0]) {
718     if (ExtraCode[1] != 0) return true; // Unknown modifier.
719 
720     switch (ExtraCode[0]) {
721     default: return true;  // Unknown modifier.
722     case 'b': // Print QImode register
723     case 'h': // Print QImode high register
724     case 'w': // Print HImode register
725     case 'k': // Print SImode register
726     case 'q': // Print SImode register
727       // These only apply to registers, ignore on mem.
728       break;
729     case 'H':
730       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
731         return true;  // Unsupported modifier in Intel inline assembly.
732       } else {
733         PrintMemReference(MI, OpNo, O, "H");
734       }
735       return false;
736    // Print memory only with displacement. The Modifer 'P' is used in inline
737    // asm to present a call symbol or a global symbol which can not use base
738    // reg or index reg.
739     case 'P':
740       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
741         PrintIntelMemReference(MI, OpNo, O, "disp-only");
742       } else {
743         PrintMemReference(MI, OpNo, O, "disp-only");
744       }
745       return false;
746     }
747   }
748   if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
749     PrintIntelMemReference(MI, OpNo, O, nullptr);
750   } else {
751     PrintMemReference(MI, OpNo, O, nullptr);
752   }
753   return false;
754 }
755 
756 void X86AsmPrinter::emitStartOfAsmFile(Module &M) {
757   const Triple &TT = TM.getTargetTriple();
758 
759   if (TT.isOSBinFormatELF()) {
760     // Assemble feature flags that may require creation of a note section.
761     unsigned FeatureFlagsAnd = 0;
762     if (M.getModuleFlag("cf-protection-branch"))
763       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
764     if (M.getModuleFlag("cf-protection-return"))
765       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
766 
767     if (FeatureFlagsAnd) {
768       // Emit a .note.gnu.property section with the flags.
769       if (!TT.isArch32Bit() && !TT.isArch64Bit())
770         llvm_unreachable("CFProtection used on invalid architecture!");
771       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
772       MCSection *Nt = MMI->getContext().getELFSection(
773           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
774       OutStreamer->switchSection(Nt);
775 
776       // Emitting note header.
777       const int WordSize = TT.isArch64Bit() && !TT.isX32() ? 8 : 4;
778       emitAlignment(WordSize == 4 ? Align(4) : Align(8));
779       OutStreamer->emitIntValue(4, 4 /*size*/); // data size for "GNU\0"
780       OutStreamer->emitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
781       OutStreamer->emitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
782       OutStreamer->emitBytes(StringRef("GNU", 4)); // note name
783 
784       // Emitting an Elf_Prop for the CET properties.
785       OutStreamer->emitInt32(ELF::GNU_PROPERTY_X86_FEATURE_1_AND);
786       OutStreamer->emitInt32(4);                          // data size
787       OutStreamer->emitInt32(FeatureFlagsAnd);            // data
788       emitAlignment(WordSize == 4 ? Align(4) : Align(8)); // padding
789 
790       OutStreamer->endSection(Nt);
791       OutStreamer->switchSection(Cur);
792     }
793   }
794 
795   if (TT.isOSBinFormatMachO())
796     OutStreamer->switchSection(getObjFileLowering().getTextSection());
797 
798   if (TT.isOSBinFormatCOFF()) {
799     // Emit an absolute @feat.00 symbol.
800     MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
801     OutStreamer->beginCOFFSymbolDef(S);
802     OutStreamer->emitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
803     OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
804     OutStreamer->endCOFFSymbolDef();
805     int64_t Feat00Value = 0;
806 
807     if (TT.getArch() == Triple::x86) {
808       // According to the PE-COFF spec, the LSB of this value marks the object
809       // for "registered SEH".  This means that all SEH handler entry points
810       // must be registered in .sxdata.  Use of any unregistered handlers will
811       // cause the process to terminate immediately.  LLVM does not know how to
812       // register any SEH handlers, so its object files should be safe.
813       Feat00Value |= COFF::Feat00Flags::SafeSEH;
814     }
815 
816     if (M.getModuleFlag("cfguard")) {
817       // Object is CFG-aware.
818       Feat00Value |= COFF::Feat00Flags::GuardCF;
819     }
820 
821     if (M.getModuleFlag("ehcontguard")) {
822       // Object also has EHCont.
823       Feat00Value |= COFF::Feat00Flags::GuardEHCont;
824     }
825 
826     if (M.getModuleFlag("ms-kernel")) {
827       // Object is compiled with /kernel.
828       Feat00Value |= COFF::Feat00Flags::Kernel;
829     }
830 
831     OutStreamer->emitSymbolAttribute(S, MCSA_Global);
832     OutStreamer->emitAssignment(
833         S, MCConstantExpr::create(Feat00Value, MMI->getContext()));
834   }
835   OutStreamer->emitSyntaxDirective();
836 
837   // If this is not inline asm and we're in 16-bit
838   // mode prefix assembly with .code16.
839   bool is16 = TT.getEnvironment() == Triple::CODE16;
840   if (M.getModuleInlineAsm().empty() && is16)
841     OutStreamer->emitAssemblerFlag(MCAF_Code16);
842 }
843 
844 static void
845 emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
846                          MachineModuleInfoImpl::StubValueTy &MCSym) {
847   // L_foo$stub:
848   OutStreamer.emitLabel(StubLabel);
849   //   .indirect_symbol _foo
850   OutStreamer.emitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
851 
852   if (MCSym.getInt())
853     // External to current translation unit.
854     OutStreamer.emitIntValue(0, 4/*size*/);
855   else
856     // Internal to current translation unit.
857     //
858     // When we place the LSDA into the TEXT section, the type info
859     // pointers need to be indirect and pc-rel. We accomplish this by
860     // using NLPs; however, sometimes the types are local to the file.
861     // We need to fill in the value for the NLP in those cases.
862     OutStreamer.emitValue(
863         MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
864         4 /*size*/);
865 }
866 
867 static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
868 
869   MachineModuleInfoMachO &MMIMacho =
870       MMI->getObjFileInfo<MachineModuleInfoMachO>();
871 
872   // Output stubs for dynamically-linked functions.
873   MachineModuleInfoMachO::SymbolListTy Stubs;
874 
875   // Output stubs for external and common global variables.
876   Stubs = MMIMacho.GetGVStubList();
877   if (!Stubs.empty()) {
878     OutStreamer.switchSection(MMI->getContext().getMachOSection(
879         "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
880         SectionKind::getMetadata()));
881 
882     for (auto &Stub : Stubs)
883       emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
884 
885     Stubs.clear();
886     OutStreamer.addBlankLine();
887   }
888 }
889 
890 void X86AsmPrinter::emitEndOfAsmFile(Module &M) {
891   const Triple &TT = TM.getTargetTriple();
892 
893   if (TT.isOSBinFormatMachO()) {
894     // Mach-O uses non-lazy symbol stubs to encode per-TU information into
895     // global table for symbol lookup.
896     emitNonLazyStubs(MMI, *OutStreamer);
897 
898     // Emit fault map information.
899     FM.serializeToFaultMapSection();
900 
901     // This flag tells the linker that no global symbols contain code that fall
902     // through to other global symbols (e.g. an implementation of multiple entry
903     // points). If this doesn't occur, the linker can safely perform dead code
904     // stripping. Since LLVM never generates code that does this, it is always
905     // safe to set.
906     OutStreamer->emitAssemblerFlag(MCAF_SubsectionsViaSymbols);
907   } else if (TT.isOSBinFormatCOFF()) {
908     if (MMI->usesMSVCFloatingPoint()) {
909       // In Windows' libcmt.lib, there is a file which is linked in only if the
910       // symbol _fltused is referenced. Linking this in causes some
911       // side-effects:
912       //
913       // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
914       // 64-bit mantissas at program start.
915       //
916       // 2. It links in support routines for floating-point in scanf and printf.
917       //
918       // MSVC emits an undefined reference to _fltused when there are any
919       // floating point operations in the program (including calls). A program
920       // that only has: `scanf("%f", &global_float);` may fail to trigger this,
921       // but oh well...that's a documented issue.
922       StringRef SymbolName =
923           (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
924       MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
925       OutStreamer->emitSymbolAttribute(S, MCSA_Global);
926       return;
927     }
928   } else if (TT.isOSBinFormatELF()) {
929     FM.serializeToFaultMapSection();
930   }
931 
932   // Emit __morestack address if needed for indirect calls.
933   if (TT.getArch() == Triple::x86_64 && TM.getCodeModel() == CodeModel::Large) {
934     if (MCSymbol *AddrSymbol = OutContext.lookupSymbol("__morestack_addr")) {
935       Align Alignment(1);
936       MCSection *ReadOnlySection = getObjFileLowering().getSectionForConstant(
937           getDataLayout(), SectionKind::getReadOnly(),
938           /*C=*/nullptr, Alignment);
939       OutStreamer->switchSection(ReadOnlySection);
940       OutStreamer->emitLabel(AddrSymbol);
941 
942       unsigned PtrSize = MAI->getCodePointerSize();
943       OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("__morestack"),
944                                    PtrSize);
945     }
946   }
947 }
948 
949 //===----------------------------------------------------------------------===//
950 // Target Registry Stuff
951 //===----------------------------------------------------------------------===//
952 
953 // Force static initialization.
954 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeX86AsmPrinter() {
955   RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
956   RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
957 }
958