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/X86MCTargetDesc.h"
18 #include "MCTargetDesc/X86TargetStreamer.h"
19 #include "TargetInfo/X86TargetInfo.h"
20 #include "X86InstrInfo.h"
21 #include "X86MachineFunctionInfo.h"
22 #include "X86Subtarget.h"
23 #include "llvm/BinaryFormat/COFF.h"
24 #include "llvm/BinaryFormat/ELF.h"
25 #include "llvm/CodeGen/MachineConstantPool.h"
26 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
27 #include "llvm/CodeGen/MachineValueType.h"
28 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
29 #include "llvm/IR/DerivedTypes.h"
30 #include "llvm/IR/InlineAsm.h"
31 #include "llvm/IR/Mangler.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/Type.h"
34 #include "llvm/MC/MCAsmInfo.h"
35 #include "llvm/MC/MCCodeEmitter.h"
36 #include "llvm/MC/MCContext.h"
37 #include "llvm/MC/MCExpr.h"
38 #include "llvm/MC/MCInst.h"
39 #include "llvm/MC/MCInstBuilder.h"
40 #include "llvm/MC/MCSectionCOFF.h"
41 #include "llvm/MC/MCSectionELF.h"
42 #include "llvm/MC/MCSectionMachO.h"
43 #include "llvm/MC/MCStreamer.h"
44 #include "llvm/MC/MCSymbol.h"
45 #include "llvm/MC/TargetRegistry.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/ErrorHandling.h"
48 #include "llvm/Target/TargetMachine.h"
49 
50 using namespace llvm;
51 
X86AsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)52 X86AsmPrinter::X86AsmPrinter(TargetMachine &TM,
53                              std::unique_ptr<MCStreamer> Streamer)
54     : AsmPrinter(TM, std::move(Streamer)), FM(*this) {}
55 
56 //===----------------------------------------------------------------------===//
57 // Primitive Helper Functions.
58 //===----------------------------------------------------------------------===//
59 
60 /// runOnMachineFunction - Emit the function body.
61 ///
runOnMachineFunction(MachineFunction & MF)62 bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
63   Subtarget = &MF.getSubtarget<X86Subtarget>();
64 
65   SMShadowTracker.startFunction(MF);
66   CodeEmitter.reset(TM.getTarget().createMCCodeEmitter(
67       *Subtarget->getInstrInfo(), MF.getContext()));
68 
69   EmitFPOData =
70       Subtarget->isTargetWin32() && MF.getMMI().getModule()->getCodeViewFlag();
71 
72   IndCSPrefix =
73       MF.getMMI().getModule()->getModuleFlag("indirect_branch_cs_prefix");
74 
75   SetupMachineFunction(MF);
76 
77   if (Subtarget->isTargetCOFF()) {
78     bool Local = MF.getFunction().hasLocalLinkage();
79     OutStreamer->beginCOFFSymbolDef(CurrentFnSym);
80     OutStreamer->emitCOFFSymbolStorageClass(
81         Local ? COFF::IMAGE_SYM_CLASS_STATIC : COFF::IMAGE_SYM_CLASS_EXTERNAL);
82     OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
83                                     << COFF::SCT_COMPLEX_TYPE_SHIFT);
84     OutStreamer->endCOFFSymbolDef();
85   }
86 
87   // Emit the rest of the function body.
88   emitFunctionBody();
89 
90   // Emit the XRay table for this function.
91   emitXRayTable();
92 
93   EmitFPOData = false;
94 
95   IndCSPrefix = false;
96 
97   // We didn't modify anything.
98   return false;
99 }
100 
emitFunctionBodyStart()101 void X86AsmPrinter::emitFunctionBodyStart() {
102   if (EmitFPOData) {
103     auto *XTS =
104         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
105     XTS->emitFPOProc(
106         CurrentFnSym,
107         MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
108   }
109 }
110 
emitFunctionBodyEnd()111 void X86AsmPrinter::emitFunctionBodyEnd() {
112   if (EmitFPOData) {
113     auto *XTS =
114         static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
115     XTS->emitFPOEndProc();
116   }
117 }
118 
MaskKCFIType(uint32_t Value)119 uint32_t X86AsmPrinter::MaskKCFIType(uint32_t Value) {
120   // If the type hash matches an invalid pattern, mask the value.
121   const uint32_t InvalidValues[] = {
122       0xFA1E0FF3, /* ENDBR64 */
123       0xFB1E0FF3, /* ENDBR32 */
124   };
125   for (uint32_t N : InvalidValues) {
126     // LowerKCFI_CHECK emits -Value for indirect call checks, so we must also
127     // mask that. Note that -(Value + 1) == ~Value.
128     if (N == Value || -N == Value)
129       return Value + 1;
130   }
131   return Value;
132 }
133 
EmitKCFITypePadding(const MachineFunction & MF,bool HasType)134 void X86AsmPrinter::EmitKCFITypePadding(const MachineFunction &MF,
135                                         bool HasType) {
136   // Keep the function entry aligned, taking patchable-function-prefix into
137   // account if set.
138   int64_t PrefixBytes = 0;
139   (void)MF.getFunction()
140       .getFnAttribute("patchable-function-prefix")
141       .getValueAsString()
142       .getAsInteger(10, PrefixBytes);
143 
144   // Also take the type identifier into account if we're emitting
145   // one. Otherwise, just pad with nops. The X86::MOV32ri instruction emitted
146   // in X86AsmPrinter::emitKCFITypeId is 5 bytes long.
147   if (HasType)
148     PrefixBytes += 5;
149 
150   emitNops(offsetToAlignment(PrefixBytes, MF.getAlignment()));
151 }
152 
153 /// emitKCFITypeId - Emit the KCFI type information in architecture specific
154 /// format.
emitKCFITypeId(const MachineFunction & MF)155 void X86AsmPrinter::emitKCFITypeId(const MachineFunction &MF) {
156   const Function &F = MF.getFunction();
157   if (!F.getParent()->getModuleFlag("kcfi"))
158     return;
159 
160   ConstantInt *Type = nullptr;
161   if (const MDNode *MD = F.getMetadata(LLVMContext::MD_kcfi_type))
162     Type = mdconst::extract<ConstantInt>(MD->getOperand(0));
163 
164   // If we don't have a type to emit, just emit padding if needed to maintain
165   // the same alignment for all functions.
166   if (!Type) {
167     EmitKCFITypePadding(MF, /*HasType=*/false);
168     return;
169   }
170 
171   // Emit a function symbol for the type data to avoid unreachable instruction
172   // warnings from binary validation tools, and use the same linkage as the
173   // parent function. Note that using local linkage would result in duplicate
174   // symbols for weak parent functions.
175   MCSymbol *FnSym = OutContext.getOrCreateSymbol("__cfi_" + MF.getName());
176   emitLinkage(&MF.getFunction(), FnSym);
177   if (MAI->hasDotTypeDotSizeDirective())
178     OutStreamer->emitSymbolAttribute(FnSym, MCSA_ELF_TypeFunction);
179   OutStreamer->emitLabel(FnSym);
180 
181   // Embed the type hash in the X86::MOV32ri instruction to avoid special
182   // casing object file parsers.
183   EmitKCFITypePadding(MF);
184   EmitAndCountInstruction(MCInstBuilder(X86::MOV32ri)
185                               .addReg(X86::EAX)
186                               .addImm(MaskKCFIType(Type->getZExtValue())));
187 
188   if (MAI->hasDotTypeDotSizeDirective()) {
189     MCSymbol *EndSym = OutContext.createTempSymbol("cfi_func_end");
190     OutStreamer->emitLabel(EndSym);
191 
192     const MCExpr *SizeExp = MCBinaryExpr::createSub(
193         MCSymbolRefExpr::create(EndSym, OutContext),
194         MCSymbolRefExpr::create(FnSym, OutContext), OutContext);
195     OutStreamer->emitELFSize(FnSym, SizeExp);
196   }
197 }
198 
199 /// PrintSymbolOperand - Print a raw symbol reference operand.  This handles
200 /// jump tables, constant pools, global address and external symbols, all of
201 /// which print to a label with various suffixes for relocation types etc.
PrintSymbolOperand(const MachineOperand & MO,raw_ostream & O)202 void X86AsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
203                                        raw_ostream &O) {
204   switch (MO.getType()) {
205   default: llvm_unreachable("unknown symbol type!");
206   case MachineOperand::MO_ConstantPoolIndex:
207     GetCPISymbol(MO.getIndex())->print(O, MAI);
208     printOffset(MO.getOffset(), O);
209     break;
210   case MachineOperand::MO_GlobalAddress: {
211     const GlobalValue *GV = MO.getGlobal();
212 
213     MCSymbol *GVSym;
214     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
215         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE)
216       GVSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
217     else
218       GVSym = getSymbolPreferLocal(*GV);
219 
220     // Handle dllimport linkage.
221     if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
222       GVSym = OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
223     else if (MO.getTargetFlags() == X86II::MO_COFFSTUB)
224       GVSym =
225           OutContext.getOrCreateSymbol(Twine(".refptr.") + GVSym->getName());
226 
227     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
228         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
229       MCSymbol *Sym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
230       MachineModuleInfoImpl::StubValueTy &StubSym =
231           MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(Sym);
232       if (!StubSym.getPointer())
233         StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
234                                                      !GV->hasInternalLinkage());
235     }
236 
237     // If the name begins with a dollar-sign, enclose it in parens.  We do this
238     // to avoid having it look like an integer immediate to the assembler.
239     if (GVSym->getName()[0] != '$')
240       GVSym->print(O, MAI);
241     else {
242       O << '(';
243       GVSym->print(O, MAI);
244       O << ')';
245     }
246     printOffset(MO.getOffset(), O);
247     break;
248   }
249   }
250 
251   switch (MO.getTargetFlags()) {
252   default:
253     llvm_unreachable("Unknown target flag on GV operand");
254   case X86II::MO_NO_FLAG:    // No flag.
255     break;
256   case X86II::MO_DARWIN_NONLAZY:
257   case X86II::MO_DLLIMPORT:
258   case X86II::MO_COFFSTUB:
259     // These affect the name of the symbol, not any suffix.
260     break;
261   case X86II::MO_GOT_ABSOLUTE_ADDRESS:
262     O << " + [.-";
263     MF->getPICBaseSymbol()->print(O, MAI);
264     O << ']';
265     break;
266   case X86II::MO_PIC_BASE_OFFSET:
267   case X86II::MO_DARWIN_NONLAZY_PIC_BASE:
268     O << '-';
269     MF->getPICBaseSymbol()->print(O, MAI);
270     break;
271   case X86II::MO_TLSGD:     O << "@TLSGD";     break;
272   case X86II::MO_TLSLD:     O << "@TLSLD";     break;
273   case X86II::MO_TLSLDM:    O << "@TLSLDM";    break;
274   case X86II::MO_GOTTPOFF:  O << "@GOTTPOFF";  break;
275   case X86II::MO_INDNTPOFF: O << "@INDNTPOFF"; break;
276   case X86II::MO_TPOFF:     O << "@TPOFF";     break;
277   case X86II::MO_DTPOFF:    O << "@DTPOFF";    break;
278   case X86II::MO_NTPOFF:    O << "@NTPOFF";    break;
279   case X86II::MO_GOTNTPOFF: O << "@GOTNTPOFF"; break;
280   case X86II::MO_GOTPCREL:  O << "@GOTPCREL";  break;
281   case X86II::MO_GOTPCREL_NORELAX: O << "@GOTPCREL_NORELAX"; break;
282   case X86II::MO_GOT:       O << "@GOT";       break;
283   case X86II::MO_GOTOFF:    O << "@GOTOFF";    break;
284   case X86II::MO_PLT:       O << "@PLT";       break;
285   case X86II::MO_TLVP:      O << "@TLVP";      break;
286   case X86II::MO_TLVP_PIC_BASE:
287     O << "@TLVP" << '-';
288     MF->getPICBaseSymbol()->print(O, MAI);
289     break;
290   case X86II::MO_SECREL:    O << "@SECREL32";  break;
291   }
292 }
293 
PrintOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)294 void X86AsmPrinter::PrintOperand(const MachineInstr *MI, unsigned OpNo,
295                                  raw_ostream &O) {
296   const MachineOperand &MO = MI->getOperand(OpNo);
297   const bool IsATT = MI->getInlineAsmDialect() == InlineAsm::AD_ATT;
298   switch (MO.getType()) {
299   default: llvm_unreachable("unknown operand type!");
300   case MachineOperand::MO_Register: {
301     if (IsATT)
302       O << '%';
303     O << X86ATTInstPrinter::getRegisterName(MO.getReg());
304     return;
305   }
306 
307   case MachineOperand::MO_Immediate:
308     if (IsATT)
309       O << '$';
310     O << MO.getImm();
311     return;
312 
313   case MachineOperand::MO_ConstantPoolIndex:
314   case MachineOperand::MO_GlobalAddress: {
315     switch (MI->getInlineAsmDialect()) {
316     case InlineAsm::AD_ATT:
317       O << '$';
318       break;
319     case InlineAsm::AD_Intel:
320       O << "offset ";
321       break;
322     }
323     PrintSymbolOperand(MO, O);
324     break;
325   }
326   case MachineOperand::MO_BlockAddress: {
327     MCSymbol *Sym = GetBlockAddressSymbol(MO.getBlockAddress());
328     Sym->print(O, MAI);
329     break;
330   }
331   }
332 }
333 
334 /// PrintModifiedOperand - Print subregisters based on supplied modifier,
335 /// deferring to PrintOperand() if no modifier was supplied or if operand is not
336 /// a register.
PrintModifiedOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)337 void X86AsmPrinter::PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
338                                          raw_ostream &O, const char *Modifier) {
339   const MachineOperand &MO = MI->getOperand(OpNo);
340   if (!Modifier || !MO.isReg())
341     return PrintOperand(MI, OpNo, O);
342   if (MI->getInlineAsmDialect() == InlineAsm::AD_ATT)
343     O << '%';
344   Register Reg = MO.getReg();
345   if (strncmp(Modifier, "subreg", strlen("subreg")) == 0) {
346     unsigned Size = (strcmp(Modifier+6,"64") == 0) ? 64 :
347         (strcmp(Modifier+6,"32") == 0) ? 32 :
348         (strcmp(Modifier+6,"16") == 0) ? 16 : 8;
349     Reg = getX86SubSuperRegister(Reg, Size);
350   }
351   O << X86ATTInstPrinter::getRegisterName(Reg);
352 }
353 
354 /// PrintPCRelImm - This is used to print an immediate value that ends up
355 /// being encoded as a pc-relative value.  These print slightly differently, for
356 /// example, a $ is not emitted.
PrintPCRelImm(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)357 void X86AsmPrinter::PrintPCRelImm(const MachineInstr *MI, unsigned OpNo,
358                                   raw_ostream &O) {
359   const MachineOperand &MO = MI->getOperand(OpNo);
360   switch (MO.getType()) {
361   default: llvm_unreachable("Unknown pcrel immediate operand");
362   case MachineOperand::MO_Register:
363     // pc-relativeness was handled when computing the value in the reg.
364     PrintOperand(MI, OpNo, O);
365     return;
366   case MachineOperand::MO_Immediate:
367     O << MO.getImm();
368     return;
369   case MachineOperand::MO_GlobalAddress:
370     PrintSymbolOperand(MO, O);
371     return;
372   }
373 }
374 
PrintLeaMemReference(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)375 void X86AsmPrinter::PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
376                                          raw_ostream &O, const char *Modifier) {
377   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
378   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
379   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
380 
381   // If we really don't want to print out (rip), don't.
382   bool HasBaseReg = BaseReg.getReg() != 0;
383   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
384       BaseReg.getReg() == X86::RIP)
385     HasBaseReg = false;
386 
387   // HasParenPart - True if we will print out the () part of the mem ref.
388   bool HasParenPart = IndexReg.getReg() || HasBaseReg;
389 
390   switch (DispSpec.getType()) {
391   default:
392     llvm_unreachable("unknown operand type!");
393   case MachineOperand::MO_Immediate: {
394     int DispVal = DispSpec.getImm();
395     if (DispVal || !HasParenPart)
396       O << DispVal;
397     break;
398   }
399   case MachineOperand::MO_GlobalAddress:
400   case MachineOperand::MO_ConstantPoolIndex:
401     PrintSymbolOperand(DispSpec, O);
402     break;
403   }
404 
405   if (Modifier && strcmp(Modifier, "H") == 0)
406     O << "+8";
407 
408   if (HasParenPart) {
409     assert(IndexReg.getReg() != X86::ESP &&
410            "X86 doesn't allow scaling by ESP");
411 
412     O << '(';
413     if (HasBaseReg)
414       PrintModifiedOperand(MI, OpNo + X86::AddrBaseReg, O, Modifier);
415 
416     if (IndexReg.getReg()) {
417       O << ',';
418       PrintModifiedOperand(MI, OpNo + X86::AddrIndexReg, O, Modifier);
419       unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
420       if (ScaleVal != 1)
421         O << ',' << ScaleVal;
422     }
423     O << ')';
424   }
425 }
426 
isSimpleReturn(const MachineInstr & MI)427 static bool isSimpleReturn(const MachineInstr &MI) {
428   // We exclude all tail calls here which set both isReturn and isCall.
429   return MI.getDesc().isReturn() && !MI.getDesc().isCall();
430 }
431 
isIndirectBranchOrTailCall(const MachineInstr & MI)432 static bool isIndirectBranchOrTailCall(const MachineInstr &MI) {
433   unsigned Opc = MI.getOpcode();
434   return MI.getDesc().isIndirectBranch() /*Make below code in a good shape*/ ||
435          Opc == X86::TAILJMPr || Opc == X86::TAILJMPm ||
436          Opc == X86::TAILJMPr64 || Opc == X86::TAILJMPm64 ||
437          Opc == X86::TCRETURNri || Opc == X86::TCRETURNmi ||
438          Opc == X86::TCRETURNri64 || Opc == X86::TCRETURNmi64 ||
439          Opc == X86::TAILJMPr64_REX || Opc == X86::TAILJMPm64_REX;
440 }
441 
emitBasicBlockEnd(const MachineBasicBlock & MBB)442 void X86AsmPrinter::emitBasicBlockEnd(const MachineBasicBlock &MBB) {
443   if (Subtarget->hardenSlsRet() || Subtarget->hardenSlsIJmp()) {
444     auto I = MBB.getLastNonDebugInstr();
445     if (I != MBB.end()) {
446       if ((Subtarget->hardenSlsRet() && isSimpleReturn(*I)) ||
447           (Subtarget->hardenSlsIJmp() && isIndirectBranchOrTailCall(*I))) {
448         MCInst TmpInst;
449         TmpInst.setOpcode(X86::INT3);
450         EmitToStreamer(*OutStreamer, TmpInst);
451       }
452     }
453   }
454   AsmPrinter::emitBasicBlockEnd(MBB);
455   SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
456 }
457 
PrintMemReference(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)458 void X86AsmPrinter::PrintMemReference(const MachineInstr *MI, unsigned OpNo,
459                                       raw_ostream &O, const char *Modifier) {
460   assert(isMem(*MI, OpNo) && "Invalid memory reference!");
461   const MachineOperand &Segment = MI->getOperand(OpNo + X86::AddrSegmentReg);
462   if (Segment.getReg()) {
463     PrintModifiedOperand(MI, OpNo + X86::AddrSegmentReg, O, Modifier);
464     O << ':';
465   }
466   PrintLeaMemReference(MI, OpNo, O, Modifier);
467 }
468 
469 
PrintIntelMemReference(const MachineInstr * MI,unsigned OpNo,raw_ostream & O,const char * Modifier)470 void X86AsmPrinter::PrintIntelMemReference(const MachineInstr *MI,
471                                            unsigned OpNo, raw_ostream &O,
472                                            const char *Modifier) {
473   const MachineOperand &BaseReg = MI->getOperand(OpNo + X86::AddrBaseReg);
474   unsigned ScaleVal = MI->getOperand(OpNo + X86::AddrScaleAmt).getImm();
475   const MachineOperand &IndexReg = MI->getOperand(OpNo + X86::AddrIndexReg);
476   const MachineOperand &DispSpec = MI->getOperand(OpNo + X86::AddrDisp);
477   const MachineOperand &SegReg = MI->getOperand(OpNo + X86::AddrSegmentReg);
478 
479   // If we really don't want to print out (rip), don't.
480   bool HasBaseReg = BaseReg.getReg() != 0;
481   if (HasBaseReg && Modifier && !strcmp(Modifier, "no-rip") &&
482       BaseReg.getReg() == X86::RIP)
483     HasBaseReg = false;
484 
485   // If we really just want to print out displacement.
486   if (Modifier && (DispSpec.isGlobal() || DispSpec.isSymbol()) &&
487       !strcmp(Modifier, "disp-only")) {
488     HasBaseReg = false;
489   }
490 
491   // If this has a segment register, print it.
492   if (SegReg.getReg()) {
493     PrintOperand(MI, OpNo + X86::AddrSegmentReg, O);
494     O << ':';
495   }
496 
497   O << '[';
498 
499   bool NeedPlus = false;
500   if (HasBaseReg) {
501     PrintOperand(MI, OpNo + X86::AddrBaseReg, O);
502     NeedPlus = true;
503   }
504 
505   if (IndexReg.getReg()) {
506     if (NeedPlus) O << " + ";
507     if (ScaleVal != 1)
508       O << ScaleVal << '*';
509     PrintOperand(MI, OpNo + X86::AddrIndexReg, O);
510     NeedPlus = true;
511   }
512 
513   if (!DispSpec.isImm()) {
514     if (NeedPlus) O << " + ";
515     // Do not add `offset` operator. Matches the behaviour of
516     // X86IntelInstPrinter::printMemReference.
517     PrintSymbolOperand(DispSpec, O);
518   } else {
519     int64_t DispVal = DispSpec.getImm();
520     if (DispVal || (!IndexReg.getReg() && !HasBaseReg)) {
521       if (NeedPlus) {
522         if (DispVal > 0)
523           O << " + ";
524         else {
525           O << " - ";
526           DispVal = -DispVal;
527         }
528       }
529       O << DispVal;
530     }
531   }
532   O << ']';
533 }
534 
getIFuncMCSubtargetInfo() const535 const MCSubtargetInfo *X86AsmPrinter::getIFuncMCSubtargetInfo() const {
536   assert(Subtarget);
537   return Subtarget;
538 }
539 
emitMachOIFuncStubBody(Module & M,const GlobalIFunc & GI,MCSymbol * LazyPointer)540 void X86AsmPrinter::emitMachOIFuncStubBody(Module &M, const GlobalIFunc &GI,
541                                            MCSymbol *LazyPointer) {
542   // _ifunc:
543   //   jmpq *lazy_pointer(%rip)
544 
545   OutStreamer->emitInstruction(
546       MCInstBuilder(X86::JMP32m)
547           .addReg(X86::RIP)
548           .addImm(1)
549           .addReg(0)
550           .addOperand(MCOperand::createExpr(
551               MCSymbolRefExpr::create(LazyPointer, OutContext)))
552           .addReg(0),
553       *Subtarget);
554 }
555 
emitMachOIFuncStubHelperBody(Module & M,const GlobalIFunc & GI,MCSymbol * LazyPointer)556 void X86AsmPrinter::emitMachOIFuncStubHelperBody(Module &M,
557                                                  const GlobalIFunc &GI,
558                                                  MCSymbol *LazyPointer) {
559   // _ifunc.stub_helper:
560   //   push %rax
561   //   push %rdi
562   //   push %rsi
563   //   push %rdx
564   //   push %rcx
565   //   push %r8
566   //   push %r9
567   //   callq foo
568   //   movq %rax,lazy_pointer(%rip)
569   //   pop %r9
570   //   pop %r8
571   //   pop %rcx
572   //   pop %rdx
573   //   pop %rsi
574   //   pop %rdi
575   //   pop %rax
576   //   jmpq *lazy_pointer(%rip)
577 
578   for (int Reg :
579        {X86::RAX, X86::RDI, X86::RSI, X86::RDX, X86::RCX, X86::R8, X86::R9})
580     OutStreamer->emitInstruction(MCInstBuilder(X86::PUSH64r).addReg(Reg),
581                                  *Subtarget);
582 
583   OutStreamer->emitInstruction(
584       MCInstBuilder(X86::CALL64pcrel32)
585           .addOperand(MCOperand::createExpr(lowerConstant(GI.getResolver()))),
586       *Subtarget);
587 
588   OutStreamer->emitInstruction(
589       MCInstBuilder(X86::MOV64mr)
590           .addReg(X86::RIP)
591           .addImm(1)
592           .addReg(0)
593           .addOperand(MCOperand::createExpr(
594               MCSymbolRefExpr::create(LazyPointer, OutContext)))
595           .addReg(0)
596           .addReg(X86::RAX),
597       *Subtarget);
598 
599   for (int Reg :
600        {X86::R9, X86::R8, X86::RCX, X86::RDX, X86::RSI, X86::RDI, X86::RAX})
601     OutStreamer->emitInstruction(MCInstBuilder(X86::POP64r).addReg(Reg),
602                                  *Subtarget);
603 
604   OutStreamer->emitInstruction(
605       MCInstBuilder(X86::JMP32m)
606           .addReg(X86::RIP)
607           .addImm(1)
608           .addReg(0)
609           .addOperand(MCOperand::createExpr(
610               MCSymbolRefExpr::create(LazyPointer, OutContext)))
611           .addReg(0),
612       *Subtarget);
613 }
614 
printAsmMRegister(const X86AsmPrinter & P,const MachineOperand & MO,char Mode,raw_ostream & O)615 static bool printAsmMRegister(const X86AsmPrinter &P, const MachineOperand &MO,
616                               char Mode, raw_ostream &O) {
617   Register Reg = MO.getReg();
618   bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
619 
620   if (!X86::GR8RegClass.contains(Reg) &&
621       !X86::GR16RegClass.contains(Reg) &&
622       !X86::GR32RegClass.contains(Reg) &&
623       !X86::GR64RegClass.contains(Reg))
624     return true;
625 
626   switch (Mode) {
627   default: return true;  // Unknown mode.
628   case 'b': // Print QImode register
629     Reg = getX86SubSuperRegister(Reg, 8);
630     break;
631   case 'h': // Print QImode high register
632     Reg = getX86SubSuperRegister(Reg, 8, true);
633     if (!Reg.isValid())
634       return true;
635     break;
636   case 'w': // Print HImode register
637     Reg = getX86SubSuperRegister(Reg, 16);
638     break;
639   case 'k': // Print SImode register
640     Reg = getX86SubSuperRegister(Reg, 32);
641     break;
642   case 'V':
643     EmitPercent = false;
644     [[fallthrough]];
645   case 'q':
646     // Print 64-bit register names if 64-bit integer registers are available.
647     // Otherwise, print 32-bit register names.
648     Reg = getX86SubSuperRegister(Reg, P.getSubtarget().is64Bit() ? 64 : 32);
649     break;
650   }
651 
652   if (EmitPercent)
653     O << '%';
654 
655   O << X86ATTInstPrinter::getRegisterName(Reg);
656   return false;
657 }
658 
printAsmVRegister(const MachineOperand & MO,char Mode,raw_ostream & O)659 static bool printAsmVRegister(const MachineOperand &MO, char Mode,
660                               raw_ostream &O) {
661   Register Reg = MO.getReg();
662   bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
663 
664   unsigned Index;
665   if (X86::VR128XRegClass.contains(Reg))
666     Index = Reg - X86::XMM0;
667   else if (X86::VR256XRegClass.contains(Reg))
668     Index = Reg - X86::YMM0;
669   else if (X86::VR512RegClass.contains(Reg))
670     Index = Reg - X86::ZMM0;
671   else
672     return true;
673 
674   switch (Mode) {
675   default: // Unknown mode.
676     return true;
677   case 'x': // Print V4SFmode register
678     Reg = X86::XMM0 + Index;
679     break;
680   case 't': // Print V8SFmode register
681     Reg = X86::YMM0 + Index;
682     break;
683   case 'g': // Print V16SFmode register
684     Reg = X86::ZMM0 + Index;
685     break;
686   }
687 
688   if (EmitPercent)
689     O << '%';
690 
691   O << X86ATTInstPrinter::getRegisterName(Reg);
692   return false;
693 }
694 
695 /// PrintAsmOperand - Print out an operand for an inline asm expression.
696 ///
PrintAsmOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & O)697 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
698                                     const char *ExtraCode, raw_ostream &O) {
699   // Does this asm operand have a single letter operand modifier?
700   if (ExtraCode && ExtraCode[0]) {
701     if (ExtraCode[1] != 0) return true; // Unknown modifier.
702 
703     const MachineOperand &MO = MI->getOperand(OpNo);
704 
705     switch (ExtraCode[0]) {
706     default:
707       // See if this is a generic print operand
708       return AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, O);
709     case 'a': // This is an address.  Currently only 'i' and 'r' are expected.
710       switch (MO.getType()) {
711       default:
712         return true;
713       case MachineOperand::MO_Immediate:
714         O << MO.getImm();
715         return false;
716       case MachineOperand::MO_ConstantPoolIndex:
717       case MachineOperand::MO_JumpTableIndex:
718       case MachineOperand::MO_ExternalSymbol:
719         llvm_unreachable("unexpected operand type!");
720       case MachineOperand::MO_GlobalAddress:
721         PrintSymbolOperand(MO, O);
722         if (Subtarget->isPICStyleRIPRel())
723           O << "(%rip)";
724         return false;
725       case MachineOperand::MO_Register:
726         O << '(';
727         PrintOperand(MI, OpNo, O);
728         O << ')';
729         return false;
730       }
731 
732     case 'c': // Don't print "$" before a global var name or constant.
733       switch (MO.getType()) {
734       default:
735         PrintOperand(MI, OpNo, O);
736         break;
737       case MachineOperand::MO_Immediate:
738         O << MO.getImm();
739         break;
740       case MachineOperand::MO_ConstantPoolIndex:
741       case MachineOperand::MO_JumpTableIndex:
742       case MachineOperand::MO_ExternalSymbol:
743         llvm_unreachable("unexpected operand type!");
744       case MachineOperand::MO_GlobalAddress:
745         PrintSymbolOperand(MO, O);
746         break;
747       }
748       return false;
749 
750     case 'A': // Print '*' before a register (it must be a register)
751       if (MO.isReg()) {
752         O << '*';
753         PrintOperand(MI, OpNo, O);
754         return false;
755       }
756       return true;
757 
758     case 'b': // Print QImode register
759     case 'h': // Print QImode high register
760     case 'w': // Print HImode register
761     case 'k': // Print SImode register
762     case 'q': // Print DImode register
763     case 'V': // Print native register without '%'
764       if (MO.isReg())
765         return printAsmMRegister(*this, MO, ExtraCode[0], O);
766       PrintOperand(MI, OpNo, O);
767       return false;
768 
769     case 'x': // Print V4SFmode register
770     case 't': // Print V8SFmode register
771     case 'g': // Print V16SFmode register
772       if (MO.isReg())
773         return printAsmVRegister(MO, ExtraCode[0], O);
774       PrintOperand(MI, OpNo, O);
775       return false;
776 
777     case 'p': {
778       const MachineOperand &MO = MI->getOperand(OpNo);
779       if (MO.getType() != MachineOperand::MO_GlobalAddress)
780         return true;
781       PrintSymbolOperand(MO, O);
782       return false;
783     }
784 
785     case 'P': // This is the operand of a call, treat specially.
786       PrintPCRelImm(MI, OpNo, O);
787       return false;
788 
789     case 'n': // Negate the immediate or print a '-' before the operand.
790       // Note: this is a temporary solution. It should be handled target
791       // independently as part of the 'MC' work.
792       if (MO.isImm()) {
793         O << -MO.getImm();
794         return false;
795       }
796       O << '-';
797     }
798   }
799 
800   PrintOperand(MI, OpNo, O);
801   return false;
802 }
803 
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & O)804 bool X86AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
805                                           const char *ExtraCode,
806                                           raw_ostream &O) {
807   if (ExtraCode && ExtraCode[0]) {
808     if (ExtraCode[1] != 0) return true; // Unknown modifier.
809 
810     switch (ExtraCode[0]) {
811     default: return true;  // Unknown modifier.
812     case 'b': // Print QImode register
813     case 'h': // Print QImode high register
814     case 'w': // Print HImode register
815     case 'k': // Print SImode register
816     case 'q': // Print SImode register
817       // These only apply to registers, ignore on mem.
818       break;
819     case 'H':
820       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
821         return true;  // Unsupported modifier in Intel inline assembly.
822       } else {
823         PrintMemReference(MI, OpNo, O, "H");
824       }
825       return false;
826    // Print memory only with displacement. The Modifer 'P' is used in inline
827    // asm to present a call symbol or a global symbol which can not use base
828    // reg or index reg.
829     case 'P':
830       if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
831         PrintIntelMemReference(MI, OpNo, O, "disp-only");
832       } else {
833         PrintMemReference(MI, OpNo, O, "disp-only");
834       }
835       return false;
836     }
837   }
838   if (MI->getInlineAsmDialect() == InlineAsm::AD_Intel) {
839     PrintIntelMemReference(MI, OpNo, O, nullptr);
840   } else {
841     PrintMemReference(MI, OpNo, O, nullptr);
842   }
843   return false;
844 }
845 
emitStartOfAsmFile(Module & M)846 void X86AsmPrinter::emitStartOfAsmFile(Module &M) {
847   const Triple &TT = TM.getTargetTriple();
848 
849   if (TT.isOSBinFormatELF()) {
850     // Assemble feature flags that may require creation of a note section.
851     unsigned FeatureFlagsAnd = 0;
852     if (M.getModuleFlag("cf-protection-branch"))
853       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
854     if (M.getModuleFlag("cf-protection-return"))
855       FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
856 
857     if (FeatureFlagsAnd) {
858       // Emit a .note.gnu.property section with the flags.
859       assert((TT.isArch32Bit() || TT.isArch64Bit()) &&
860              "CFProtection used on invalid architecture!");
861       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
862       MCSection *Nt = MMI->getContext().getELFSection(
863           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
864       OutStreamer->switchSection(Nt);
865 
866       // Emitting note header.
867       const int WordSize = TT.isArch64Bit() && !TT.isX32() ? 8 : 4;
868       emitAlignment(WordSize == 4 ? Align(4) : Align(8));
869       OutStreamer->emitIntValue(4, 4 /*size*/); // data size for "GNU\0"
870       OutStreamer->emitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
871       OutStreamer->emitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
872       OutStreamer->emitBytes(StringRef("GNU", 4)); // note name
873 
874       // Emitting an Elf_Prop for the CET properties.
875       OutStreamer->emitInt32(ELF::GNU_PROPERTY_X86_FEATURE_1_AND);
876       OutStreamer->emitInt32(4);                          // data size
877       OutStreamer->emitInt32(FeatureFlagsAnd);            // data
878       emitAlignment(WordSize == 4 ? Align(4) : Align(8)); // padding
879 
880       OutStreamer->switchSection(Cur);
881     }
882   }
883 
884   if (TT.isOSBinFormatMachO())
885     OutStreamer->switchSection(getObjFileLowering().getTextSection());
886 
887   if (TT.isOSBinFormatCOFF()) {
888     // Emit an absolute @feat.00 symbol.
889     MCSymbol *S = MMI->getContext().getOrCreateSymbol(StringRef("@feat.00"));
890     OutStreamer->beginCOFFSymbolDef(S);
891     OutStreamer->emitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
892     OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_NULL);
893     OutStreamer->endCOFFSymbolDef();
894     int64_t Feat00Value = 0;
895 
896     if (TT.getArch() == Triple::x86) {
897       // According to the PE-COFF spec, the LSB of this value marks the object
898       // for "registered SEH".  This means that all SEH handler entry points
899       // must be registered in .sxdata.  Use of any unregistered handlers will
900       // cause the process to terminate immediately.  LLVM does not know how to
901       // register any SEH handlers, so its object files should be safe.
902       Feat00Value |= COFF::Feat00Flags::SafeSEH;
903     }
904 
905     if (M.getModuleFlag("cfguard")) {
906       // Object is CFG-aware.
907       Feat00Value |= COFF::Feat00Flags::GuardCF;
908     }
909 
910     if (M.getModuleFlag("ehcontguard")) {
911       // Object also has EHCont.
912       Feat00Value |= COFF::Feat00Flags::GuardEHCont;
913     }
914 
915     if (M.getModuleFlag("ms-kernel")) {
916       // Object is compiled with /kernel.
917       Feat00Value |= COFF::Feat00Flags::Kernel;
918     }
919 
920     OutStreamer->emitSymbolAttribute(S, MCSA_Global);
921     OutStreamer->emitAssignment(
922         S, MCConstantExpr::create(Feat00Value, MMI->getContext()));
923   }
924   OutStreamer->emitSyntaxDirective();
925 
926   // If this is not inline asm and we're in 16-bit
927   // mode prefix assembly with .code16.
928   bool is16 = TT.getEnvironment() == Triple::CODE16;
929   if (M.getModuleInlineAsm().empty() && is16)
930     OutStreamer->emitAssemblerFlag(MCAF_Code16);
931 }
932 
933 static void
emitNonLazySymbolPointer(MCStreamer & OutStreamer,MCSymbol * StubLabel,MachineModuleInfoImpl::StubValueTy & MCSym)934 emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
935                          MachineModuleInfoImpl::StubValueTy &MCSym) {
936   // L_foo$stub:
937   OutStreamer.emitLabel(StubLabel);
938   //   .indirect_symbol _foo
939   OutStreamer.emitSymbolAttribute(MCSym.getPointer(), MCSA_IndirectSymbol);
940 
941   if (MCSym.getInt())
942     // External to current translation unit.
943     OutStreamer.emitIntValue(0, 4/*size*/);
944   else
945     // Internal to current translation unit.
946     //
947     // When we place the LSDA into the TEXT section, the type info
948     // pointers need to be indirect and pc-rel. We accomplish this by
949     // using NLPs; however, sometimes the types are local to the file.
950     // We need to fill in the value for the NLP in those cases.
951     OutStreamer.emitValue(
952         MCSymbolRefExpr::create(MCSym.getPointer(), OutStreamer.getContext()),
953         4 /*size*/);
954 }
955 
emitNonLazyStubs(MachineModuleInfo * MMI,MCStreamer & OutStreamer)956 static void emitNonLazyStubs(MachineModuleInfo *MMI, MCStreamer &OutStreamer) {
957 
958   MachineModuleInfoMachO &MMIMacho =
959       MMI->getObjFileInfo<MachineModuleInfoMachO>();
960 
961   // Output stubs for dynamically-linked functions.
962   MachineModuleInfoMachO::SymbolListTy Stubs;
963 
964   // Output stubs for external and common global variables.
965   Stubs = MMIMacho.GetGVStubList();
966   if (!Stubs.empty()) {
967     OutStreamer.switchSection(MMI->getContext().getMachOSection(
968         "__IMPORT", "__pointers", MachO::S_NON_LAZY_SYMBOL_POINTERS,
969         SectionKind::getMetadata()));
970 
971     for (auto &Stub : Stubs)
972       emitNonLazySymbolPointer(OutStreamer, Stub.first, Stub.second);
973 
974     Stubs.clear();
975     OutStreamer.addBlankLine();
976   }
977 }
978 
emitEndOfAsmFile(Module & M)979 void X86AsmPrinter::emitEndOfAsmFile(Module &M) {
980   const Triple &TT = TM.getTargetTriple();
981 
982   if (TT.isOSBinFormatMachO()) {
983     // Mach-O uses non-lazy symbol stubs to encode per-TU information into
984     // global table for symbol lookup.
985     emitNonLazyStubs(MMI, *OutStreamer);
986 
987     // Emit fault map information.
988     FM.serializeToFaultMapSection();
989 
990     // This flag tells the linker that no global symbols contain code that fall
991     // through to other global symbols (e.g. an implementation of multiple entry
992     // points). If this doesn't occur, the linker can safely perform dead code
993     // stripping. Since LLVM never generates code that does this, it is always
994     // safe to set.
995     OutStreamer->emitAssemblerFlag(MCAF_SubsectionsViaSymbols);
996   } else if (TT.isOSBinFormatCOFF()) {
997     if (MMI->usesMSVCFloatingPoint()) {
998       // In Windows' libcmt.lib, there is a file which is linked in only if the
999       // symbol _fltused is referenced. Linking this in causes some
1000       // side-effects:
1001       //
1002       // 1. For x86-32, it will set the x87 rounding mode to 53-bit instead of
1003       // 64-bit mantissas at program start.
1004       //
1005       // 2. It links in support routines for floating-point in scanf and printf.
1006       //
1007       // MSVC emits an undefined reference to _fltused when there are any
1008       // floating point operations in the program (including calls). A program
1009       // that only has: `scanf("%f", &global_float);` may fail to trigger this,
1010       // but oh well...that's a documented issue.
1011       StringRef SymbolName =
1012           (TT.getArch() == Triple::x86) ? "__fltused" : "_fltused";
1013       MCSymbol *S = MMI->getContext().getOrCreateSymbol(SymbolName);
1014       OutStreamer->emitSymbolAttribute(S, MCSA_Global);
1015       return;
1016     }
1017   } else if (TT.isOSBinFormatELF()) {
1018     FM.serializeToFaultMapSection();
1019   }
1020 
1021   // Emit __morestack address if needed for indirect calls.
1022   if (TT.getArch() == Triple::x86_64 && TM.getCodeModel() == CodeModel::Large) {
1023     if (MCSymbol *AddrSymbol = OutContext.lookupSymbol("__morestack_addr")) {
1024       Align Alignment(1);
1025       MCSection *ReadOnlySection = getObjFileLowering().getSectionForConstant(
1026           getDataLayout(), SectionKind::getReadOnly(),
1027           /*C=*/nullptr, Alignment);
1028       OutStreamer->switchSection(ReadOnlySection);
1029       OutStreamer->emitLabel(AddrSymbol);
1030 
1031       unsigned PtrSize = MAI->getCodePointerSize();
1032       OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("__morestack"),
1033                                    PtrSize);
1034     }
1035   }
1036 }
1037 
1038 //===----------------------------------------------------------------------===//
1039 // Target Registry Stuff
1040 //===----------------------------------------------------------------------===//
1041 
1042 // Force static initialization.
LLVMInitializeX86AsmPrinter()1043 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeX86AsmPrinter() {
1044   RegisterAsmPrinter<X86AsmPrinter> X(getTheX86_32Target());
1045   RegisterAsmPrinter<X86AsmPrinter> Y(getTheX86_64Target());
1046 }
1047