1 //===- AsmPrinter.cpp - Common AsmPrinter code ----------------------------===//
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 implements the AsmPrinter class.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/CodeGen/AsmPrinter.h"
14 #include "CodeViewDebug.h"
15 #include "DwarfDebug.h"
16 #include "DwarfException.h"
17 #include "PseudoProbePrinter.h"
18 #include "WasmException.h"
19 #include "WinCFGuard.h"
20 #include "WinException.h"
21 #include "llvm/ADT/APFloat.h"
22 #include "llvm/ADT/APInt.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/STLExtras.h"
25 #include "llvm/ADT/SmallPtrSet.h"
26 #include "llvm/ADT/SmallString.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/ADT/Statistic.h"
29 #include "llvm/ADT/StringRef.h"
30 #include "llvm/ADT/Triple.h"
31 #include "llvm/ADT/Twine.h"
32 #include "llvm/Analysis/ConstantFolding.h"
33 #include "llvm/Analysis/EHPersonalities.h"
34 #include "llvm/Analysis/MemoryLocation.h"
35 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
36 #include "llvm/BinaryFormat/COFF.h"
37 #include "llvm/BinaryFormat/Dwarf.h"
38 #include "llvm/BinaryFormat/ELF.h"
39 #include "llvm/CodeGen/GCMetadata.h"
40 #include "llvm/CodeGen/GCMetadataPrinter.h"
41 #include "llvm/CodeGen/MachineBasicBlock.h"
42 #include "llvm/CodeGen/MachineConstantPool.h"
43 #include "llvm/CodeGen/MachineDominators.h"
44 #include "llvm/CodeGen/MachineFrameInfo.h"
45 #include "llvm/CodeGen/MachineFunction.h"
46 #include "llvm/CodeGen/MachineFunctionPass.h"
47 #include "llvm/CodeGen/MachineInstr.h"
48 #include "llvm/CodeGen/MachineInstrBundle.h"
49 #include "llvm/CodeGen/MachineJumpTableInfo.h"
50 #include "llvm/CodeGen/MachineLoopInfo.h"
51 #include "llvm/CodeGen/MachineMemOperand.h"
52 #include "llvm/CodeGen/MachineModuleInfo.h"
53 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
54 #include "llvm/CodeGen/MachineOperand.h"
55 #include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
56 #include "llvm/CodeGen/StackMaps.h"
57 #include "llvm/CodeGen/TargetFrameLowering.h"
58 #include "llvm/CodeGen/TargetInstrInfo.h"
59 #include "llvm/CodeGen/TargetLowering.h"
60 #include "llvm/CodeGen/TargetOpcodes.h"
61 #include "llvm/CodeGen/TargetRegisterInfo.h"
62 #include "llvm/IR/BasicBlock.h"
63 #include "llvm/IR/Comdat.h"
64 #include "llvm/IR/Constant.h"
65 #include "llvm/IR/Constants.h"
66 #include "llvm/IR/DataLayout.h"
67 #include "llvm/IR/DebugInfoMetadata.h"
68 #include "llvm/IR/DerivedTypes.h"
69 #include "llvm/IR/Function.h"
70 #include "llvm/IR/GCStrategy.h"
71 #include "llvm/IR/GlobalAlias.h"
72 #include "llvm/IR/GlobalIFunc.h"
73 #include "llvm/IR/GlobalIndirectSymbol.h"
74 #include "llvm/IR/GlobalObject.h"
75 #include "llvm/IR/GlobalValue.h"
76 #include "llvm/IR/GlobalVariable.h"
77 #include "llvm/IR/Instruction.h"
78 #include "llvm/IR/Mangler.h"
79 #include "llvm/IR/Metadata.h"
80 #include "llvm/IR/Module.h"
81 #include "llvm/IR/Operator.h"
82 #include "llvm/IR/PseudoProbe.h"
83 #include "llvm/IR/Type.h"
84 #include "llvm/IR/Value.h"
85 #include "llvm/MC/MCAsmInfo.h"
86 #include "llvm/MC/MCContext.h"
87 #include "llvm/MC/MCDirectives.h"
88 #include "llvm/MC/MCDwarf.h"
89 #include "llvm/MC/MCExpr.h"
90 #include "llvm/MC/MCInst.h"
91 #include "llvm/MC/MCSection.h"
92 #include "llvm/MC/MCSectionCOFF.h"
93 #include "llvm/MC/MCSectionELF.h"
94 #include "llvm/MC/MCSectionMachO.h"
95 #include "llvm/MC/MCSectionXCOFF.h"
96 #include "llvm/MC/MCStreamer.h"
97 #include "llvm/MC/MCSubtargetInfo.h"
98 #include "llvm/MC/MCSymbol.h"
99 #include "llvm/MC/MCSymbolELF.h"
100 #include "llvm/MC/MCSymbolXCOFF.h"
101 #include "llvm/MC/MCTargetOptions.h"
102 #include "llvm/MC/MCValue.h"
103 #include "llvm/MC/SectionKind.h"
104 #include "llvm/Pass.h"
105 #include "llvm/Remarks/Remark.h"
106 #include "llvm/Remarks/RemarkFormat.h"
107 #include "llvm/Remarks/RemarkStreamer.h"
108 #include "llvm/Remarks/RemarkStringTable.h"
109 #include "llvm/Support/Casting.h"
110 #include "llvm/Support/CommandLine.h"
111 #include "llvm/Support/Compiler.h"
112 #include "llvm/Support/ErrorHandling.h"
113 #include "llvm/Support/FileSystem.h"
114 #include "llvm/Support/Format.h"
115 #include "llvm/Support/MathExtras.h"
116 #include "llvm/Support/Path.h"
117 #include "llvm/Support/TargetRegistry.h"
118 #include "llvm/Support/Timer.h"
119 #include "llvm/Support/raw_ostream.h"
120 #include "llvm/Target/TargetLoweringObjectFile.h"
121 #include "llvm/Target/TargetMachine.h"
122 #include "llvm/Target/TargetOptions.h"
123 #include <algorithm>
124 #include <cassert>
125 #include <cinttypes>
126 #include <cstdint>
127 #include <iterator>
128 #include <limits>
129 #include <memory>
130 #include <string>
131 #include <utility>
132 #include <vector>
133
134 using namespace llvm;
135
136 #define DEBUG_TYPE "asm-printer"
137
138 // FIXME: this option currently only applies to DWARF, and not CodeView, tables
139 static cl::opt<bool>
140 DisableDebugInfoPrinting("disable-debug-info-print", cl::Hidden,
141 cl::desc("Disable debug info printing"));
142
143 const char DWARFGroupName[] = "dwarf";
144 const char DWARFGroupDescription[] = "DWARF Emission";
145 const char DbgTimerName[] = "emit";
146 const char DbgTimerDescription[] = "Debug Info Emission";
147 const char EHTimerName[] = "write_exception";
148 const char EHTimerDescription[] = "DWARF Exception Writer";
149 const char CFGuardName[] = "Control Flow Guard";
150 const char CFGuardDescription[] = "Control Flow Guard";
151 const char CodeViewLineTablesGroupName[] = "linetables";
152 const char CodeViewLineTablesGroupDescription[] = "CodeView Line Tables";
153 const char PPTimerName[] = "emit";
154 const char PPTimerDescription[] = "Pseudo Probe Emission";
155 const char PPGroupName[] = "pseudo probe";
156 const char PPGroupDescription[] = "Pseudo Probe Emission";
157
158 STATISTIC(EmittedInsts, "Number of machine instrs printed");
159
160 char AsmPrinter::ID = 0;
161
162 using gcp_map_type = DenseMap<GCStrategy *, std::unique_ptr<GCMetadataPrinter>>;
163
getGCMap(void * & P)164 static gcp_map_type &getGCMap(void *&P) {
165 if (!P)
166 P = new gcp_map_type();
167 return *(gcp_map_type*)P;
168 }
169
170 /// getGVAlignment - Return the alignment to use for the specified global
171 /// value. This rounds up to the preferred alignment if possible and legal.
getGVAlignment(const GlobalObject * GV,const DataLayout & DL,Align InAlign)172 Align AsmPrinter::getGVAlignment(const GlobalObject *GV, const DataLayout &DL,
173 Align InAlign) {
174 Align Alignment;
175 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
176 Alignment = DL.getPreferredAlign(GVar);
177
178 // If InAlign is specified, round it to it.
179 if (InAlign > Alignment)
180 Alignment = InAlign;
181
182 // If the GV has a specified alignment, take it into account.
183 const MaybeAlign GVAlign(GV->getAlignment());
184 if (!GVAlign)
185 return Alignment;
186
187 assert(GVAlign && "GVAlign must be set");
188
189 // If the GVAlign is larger than NumBits, or if we are required to obey
190 // NumBits because the GV has an assigned section, obey it.
191 if (*GVAlign > Alignment || GV->hasSection())
192 Alignment = *GVAlign;
193 return Alignment;
194 }
195
AsmPrinter(TargetMachine & tm,std::unique_ptr<MCStreamer> Streamer)196 AsmPrinter::AsmPrinter(TargetMachine &tm, std::unique_ptr<MCStreamer> Streamer)
197 : MachineFunctionPass(ID), TM(tm), MAI(tm.getMCAsmInfo()),
198 OutContext(Streamer->getContext()), OutStreamer(std::move(Streamer)) {
199 VerboseAsm = OutStreamer->isVerboseAsm();
200 }
201
~AsmPrinter()202 AsmPrinter::~AsmPrinter() {
203 assert(!DD && Handlers.size() == NumUserHandlers &&
204 "Debug/EH info didn't get finalized");
205
206 if (GCMetadataPrinters) {
207 gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
208
209 delete &GCMap;
210 GCMetadataPrinters = nullptr;
211 }
212 }
213
isPositionIndependent() const214 bool AsmPrinter::isPositionIndependent() const {
215 return TM.isPositionIndependent();
216 }
217
218 /// getFunctionNumber - Return a unique ID for the current function.
getFunctionNumber() const219 unsigned AsmPrinter::getFunctionNumber() const {
220 return MF->getFunctionNumber();
221 }
222
getObjFileLowering() const223 const TargetLoweringObjectFile &AsmPrinter::getObjFileLowering() const {
224 return *TM.getObjFileLowering();
225 }
226
getDataLayout() const227 const DataLayout &AsmPrinter::getDataLayout() const {
228 return MMI->getModule()->getDataLayout();
229 }
230
231 // Do not use the cached DataLayout because some client use it without a Module
232 // (dsymutil, llvm-dwarfdump).
getPointerSize() const233 unsigned AsmPrinter::getPointerSize() const {
234 return TM.getPointerSize(0); // FIXME: Default address space
235 }
236
getSubtargetInfo() const237 const MCSubtargetInfo &AsmPrinter::getSubtargetInfo() const {
238 assert(MF && "getSubtargetInfo requires a valid MachineFunction!");
239 return MF->getSubtarget<MCSubtargetInfo>();
240 }
241
EmitToStreamer(MCStreamer & S,const MCInst & Inst)242 void AsmPrinter::EmitToStreamer(MCStreamer &S, const MCInst &Inst) {
243 S.emitInstruction(Inst, getSubtargetInfo());
244 }
245
emitInitialRawDwarfLocDirective(const MachineFunction & MF)246 void AsmPrinter::emitInitialRawDwarfLocDirective(const MachineFunction &MF) {
247 if (DD) {
248 assert(OutStreamer->hasRawTextSupport() &&
249 "Expected assembly output mode.");
250 (void)DD->emitInitialLocDirective(MF, /*CUID=*/0);
251 }
252 }
253
254 /// getCurrentSection() - Return the current section we are emitting to.
getCurrentSection() const255 const MCSection *AsmPrinter::getCurrentSection() const {
256 return OutStreamer->getCurrentSectionOnly();
257 }
258
getAnalysisUsage(AnalysisUsage & AU) const259 void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
260 AU.setPreservesAll();
261 MachineFunctionPass::getAnalysisUsage(AU);
262 AU.addRequired<MachineOptimizationRemarkEmitterPass>();
263 AU.addRequired<GCModuleInfo>();
264 }
265
doInitialization(Module & M)266 bool AsmPrinter::doInitialization(Module &M) {
267 auto *MMIWP = getAnalysisIfAvailable<MachineModuleInfoWrapperPass>();
268 MMI = MMIWP ? &MMIWP->getMMI() : nullptr;
269
270 // Initialize TargetLoweringObjectFile.
271 const_cast<TargetLoweringObjectFile&>(getObjFileLowering())
272 .Initialize(OutContext, TM);
273
274 const_cast<TargetLoweringObjectFile &>(getObjFileLowering())
275 .getModuleMetadata(M);
276
277 OutStreamer->InitSections(false);
278
279 if (DisableDebugInfoPrinting)
280 MMI->setDebugInfoAvailability(false);
281
282 // Emit the version-min deployment target directive if needed.
283 //
284 // FIXME: If we end up with a collection of these sorts of Darwin-specific
285 // or ELF-specific things, it may make sense to have a platform helper class
286 // that will work with the target helper class. For now keep it here, as the
287 // alternative is duplicated code in each of the target asm printers that
288 // use the directive, where it would need the same conditionalization
289 // anyway.
290 const Triple &Target = TM.getTargetTriple();
291 OutStreamer->emitVersionForTarget(Target, M.getSDKVersion());
292
293 // Allow the target to emit any magic that it wants at the start of the file.
294 emitStartOfAsmFile(M);
295
296 // Very minimal debug info. It is ignored if we emit actual debug info. If we
297 // don't, this at least helps the user find where a global came from.
298 if (MAI->hasSingleParameterDotFile()) {
299 // .file "foo.c"
300 if (MAI->hasBasenameOnlyForFileDirective())
301 OutStreamer->emitFileDirective(
302 llvm::sys::path::filename(M.getSourceFileName()));
303 else
304 OutStreamer->emitFileDirective(M.getSourceFileName());
305 }
306
307 GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
308 assert(MI && "AsmPrinter didn't require GCModuleInfo?");
309 for (auto &I : *MI)
310 if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(*I))
311 MP->beginAssembly(M, *MI, *this);
312
313 // Emit module-level inline asm if it exists.
314 if (!M.getModuleInlineAsm().empty()) {
315 // We're at the module level. Construct MCSubtarget from the default CPU
316 // and target triple.
317 std::unique_ptr<MCSubtargetInfo> STI(TM.getTarget().createMCSubtargetInfo(
318 TM.getTargetTriple().str(), TM.getTargetCPU(),
319 TM.getTargetFeatureString()));
320 assert(STI && "Unable to create subtarget info");
321 OutStreamer->AddComment("Start of file scope inline assembly");
322 OutStreamer->AddBlankLine();
323 emitInlineAsm(M.getModuleInlineAsm() + "\n",
324 OutContext.getSubtargetCopy(*STI), TM.Options.MCOptions);
325 OutStreamer->AddComment("End of file scope inline assembly");
326 OutStreamer->AddBlankLine();
327 }
328
329 if (MAI->doesSupportDebugInformation()) {
330 bool EmitCodeView = M.getCodeViewFlag();
331 if (EmitCodeView && TM.getTargetTriple().isOSWindows()) {
332 Handlers.emplace_back(std::make_unique<CodeViewDebug>(this),
333 DbgTimerName, DbgTimerDescription,
334 CodeViewLineTablesGroupName,
335 CodeViewLineTablesGroupDescription);
336 }
337 if (!EmitCodeView || M.getDwarfVersion()) {
338 if (!DisableDebugInfoPrinting) {
339 DD = new DwarfDebug(this);
340 Handlers.emplace_back(std::unique_ptr<DwarfDebug>(DD), DbgTimerName,
341 DbgTimerDescription, DWARFGroupName,
342 DWARFGroupDescription);
343 }
344 }
345 }
346
347 if (M.getNamedMetadata(PseudoProbeDescMetadataName)) {
348 PP = new PseudoProbeHandler(this, &M);
349 Handlers.emplace_back(std::unique_ptr<PseudoProbeHandler>(PP), PPTimerName,
350 PPTimerDescription, PPGroupName, PPGroupDescription);
351 }
352
353 switch (MAI->getExceptionHandlingType()) {
354 case ExceptionHandling::None:
355 // We may want to emit CFI for debug.
356 LLVM_FALLTHROUGH;
357 case ExceptionHandling::SjLj:
358 case ExceptionHandling::DwarfCFI:
359 case ExceptionHandling::ARM:
360 for (auto &F : M.getFunctionList()) {
361 if (getFunctionCFISectionType(F) != CFISection::None)
362 ModuleCFISection = getFunctionCFISectionType(F);
363 // If any function needsUnwindTableEntry(), it needs .eh_frame and hence
364 // the module needs .eh_frame. If we have found that case, we are done.
365 if (ModuleCFISection == CFISection::EH)
366 break;
367 }
368 assert(MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI ||
369 ModuleCFISection != CFISection::EH);
370 break;
371 default:
372 break;
373 }
374
375 EHStreamer *ES = nullptr;
376 switch (MAI->getExceptionHandlingType()) {
377 case ExceptionHandling::None:
378 if (!needsCFIForDebug())
379 break;
380 LLVM_FALLTHROUGH;
381 case ExceptionHandling::SjLj:
382 case ExceptionHandling::DwarfCFI:
383 ES = new DwarfCFIException(this);
384 break;
385 case ExceptionHandling::ARM:
386 ES = new ARMException(this);
387 break;
388 case ExceptionHandling::WinEH:
389 switch (MAI->getWinEHEncodingType()) {
390 default: llvm_unreachable("unsupported unwinding information encoding");
391 case WinEH::EncodingType::Invalid:
392 break;
393 case WinEH::EncodingType::X86:
394 case WinEH::EncodingType::Itanium:
395 ES = new WinException(this);
396 break;
397 }
398 break;
399 case ExceptionHandling::Wasm:
400 ES = new WasmException(this);
401 break;
402 case ExceptionHandling::AIX:
403 ES = new AIXException(this);
404 break;
405 }
406 if (ES)
407 Handlers.emplace_back(std::unique_ptr<EHStreamer>(ES), EHTimerName,
408 EHTimerDescription, DWARFGroupName,
409 DWARFGroupDescription);
410
411 // Emit tables for any value of cfguard flag (i.e. cfguard=1 or cfguard=2).
412 if (mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("cfguard")))
413 Handlers.emplace_back(std::make_unique<WinCFGuard>(this), CFGuardName,
414 CFGuardDescription, DWARFGroupName,
415 DWARFGroupDescription);
416
417 for (const HandlerInfo &HI : Handlers) {
418 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
419 HI.TimerGroupDescription, TimePassesIsEnabled);
420 HI.Handler->beginModule(&M);
421 }
422
423 return false;
424 }
425
canBeHidden(const GlobalValue * GV,const MCAsmInfo & MAI)426 static bool canBeHidden(const GlobalValue *GV, const MCAsmInfo &MAI) {
427 if (!MAI.hasWeakDefCanBeHiddenDirective())
428 return false;
429
430 return GV->canBeOmittedFromSymbolTable();
431 }
432
emitLinkage(const GlobalValue * GV,MCSymbol * GVSym) const433 void AsmPrinter::emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
434 GlobalValue::LinkageTypes Linkage = GV->getLinkage();
435 switch (Linkage) {
436 case GlobalValue::CommonLinkage:
437 case GlobalValue::LinkOnceAnyLinkage:
438 case GlobalValue::LinkOnceODRLinkage:
439 case GlobalValue::WeakAnyLinkage:
440 case GlobalValue::WeakODRLinkage:
441 if (MAI->hasWeakDefDirective()) {
442 // .globl _foo
443 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
444
445 if (!canBeHidden(GV, *MAI))
446 // .weak_definition _foo
447 OutStreamer->emitSymbolAttribute(GVSym, MCSA_WeakDefinition);
448 else
449 OutStreamer->emitSymbolAttribute(GVSym, MCSA_WeakDefAutoPrivate);
450 } else if (MAI->avoidWeakIfComdat() && GV->hasComdat()) {
451 // .globl _foo
452 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
453 //NOTE: linkonce is handled by the section the symbol was assigned to.
454 } else {
455 // .weak _foo
456 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Weak);
457 }
458 return;
459 case GlobalValue::ExternalLinkage:
460 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
461 return;
462 case GlobalValue::PrivateLinkage:
463 case GlobalValue::InternalLinkage:
464 return;
465 case GlobalValue::ExternalWeakLinkage:
466 case GlobalValue::AvailableExternallyLinkage:
467 case GlobalValue::AppendingLinkage:
468 llvm_unreachable("Should never emit this");
469 }
470 llvm_unreachable("Unknown linkage type!");
471 }
472
getNameWithPrefix(SmallVectorImpl<char> & Name,const GlobalValue * GV) const473 void AsmPrinter::getNameWithPrefix(SmallVectorImpl<char> &Name,
474 const GlobalValue *GV) const {
475 TM.getNameWithPrefix(Name, GV, getObjFileLowering().getMangler());
476 }
477
getSymbol(const GlobalValue * GV) const478 MCSymbol *AsmPrinter::getSymbol(const GlobalValue *GV) const {
479 return TM.getSymbol(GV);
480 }
481
getSymbolPreferLocal(const GlobalValue & GV) const482 MCSymbol *AsmPrinter::getSymbolPreferLocal(const GlobalValue &GV) const {
483 // On ELF, use .Lfoo$local if GV is a non-interposable GlobalObject with an
484 // exact definion (intersection of GlobalValue::hasExactDefinition() and
485 // !isInterposable()). These linkages include: external, appending, internal,
486 // private. It may be profitable to use a local alias for external. The
487 // assembler would otherwise be conservative and assume a global default
488 // visibility symbol can be interposable, even if the code generator already
489 // assumed it.
490 if (TM.getTargetTriple().isOSBinFormatELF() && GV.canBenefitFromLocalAlias()) {
491 const Module &M = *GV.getParent();
492 if (TM.getRelocationModel() != Reloc::Static &&
493 M.getPIELevel() == PIELevel::Default && GV.isDSOLocal())
494 return getSymbolWithGlobalValueBase(&GV, "$local");
495 }
496 return TM.getSymbol(&GV);
497 }
498
499 /// EmitGlobalVariable - Emit the specified global variable to the .s file.
emitGlobalVariable(const GlobalVariable * GV)500 void AsmPrinter::emitGlobalVariable(const GlobalVariable *GV) {
501 bool IsEmuTLSVar = TM.useEmulatedTLS() && GV->isThreadLocal();
502 assert(!(IsEmuTLSVar && GV->hasCommonLinkage()) &&
503 "No emulated TLS variables in the common section");
504
505 // Never emit TLS variable xyz in emulated TLS model.
506 // The initialization value is in __emutls_t.xyz instead of xyz.
507 if (IsEmuTLSVar)
508 return;
509
510 if (GV->hasInitializer()) {
511 // Check to see if this is a special global used by LLVM, if so, emit it.
512 if (emitSpecialLLVMGlobal(GV))
513 return;
514
515 // Skip the emission of global equivalents. The symbol can be emitted later
516 // on by emitGlobalGOTEquivs in case it turns out to be needed.
517 if (GlobalGOTEquivs.count(getSymbol(GV)))
518 return;
519
520 if (isVerbose()) {
521 // When printing the control variable __emutls_v.*,
522 // we don't need to print the original TLS variable name.
523 GV->printAsOperand(OutStreamer->GetCommentOS(),
524 /*PrintType=*/false, GV->getParent());
525 OutStreamer->GetCommentOS() << '\n';
526 }
527 }
528
529 MCSymbol *GVSym = getSymbol(GV);
530 MCSymbol *EmittedSym = GVSym;
531
532 // getOrCreateEmuTLSControlSym only creates the symbol with name and default
533 // attributes.
534 // GV's or GVSym's attributes will be used for the EmittedSym.
535 emitVisibility(EmittedSym, GV->getVisibility(), !GV->isDeclaration());
536
537 if (!GV->hasInitializer()) // External globals require no extra code.
538 return;
539
540 GVSym->redefineIfPossible();
541 if (GVSym->isDefined() || GVSym->isVariable())
542 OutContext.reportError(SMLoc(), "symbol '" + Twine(GVSym->getName()) +
543 "' is already defined");
544
545 if (MAI->hasDotTypeDotSizeDirective())
546 OutStreamer->emitSymbolAttribute(EmittedSym, MCSA_ELF_TypeObject);
547
548 SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
549
550 const DataLayout &DL = GV->getParent()->getDataLayout();
551 uint64_t Size = DL.getTypeAllocSize(GV->getValueType());
552
553 // If the alignment is specified, we *must* obey it. Overaligning a global
554 // with a specified alignment is a prompt way to break globals emitted to
555 // sections and expected to be contiguous (e.g. ObjC metadata).
556 const Align Alignment = getGVAlignment(GV, DL);
557
558 for (const HandlerInfo &HI : Handlers) {
559 NamedRegionTimer T(HI.TimerName, HI.TimerDescription,
560 HI.TimerGroupName, HI.TimerGroupDescription,
561 TimePassesIsEnabled);
562 HI.Handler->setSymbolSize(GVSym, Size);
563 }
564
565 // Handle common symbols
566 if (GVKind.isCommon()) {
567 if (Size == 0) Size = 1; // .comm Foo, 0 is undefined, avoid it.
568 // .comm _foo, 42, 4
569 const bool SupportsAlignment =
570 getObjFileLowering().getCommDirectiveSupportsAlignment();
571 OutStreamer->emitCommonSymbol(GVSym, Size,
572 SupportsAlignment ? Alignment.value() : 0);
573 return;
574 }
575
576 // Determine to which section this global should be emitted.
577 MCSection *TheSection = getObjFileLowering().SectionForGlobal(GV, GVKind, TM);
578
579 // If we have a bss global going to a section that supports the
580 // zerofill directive, do so here.
581 if (GVKind.isBSS() && MAI->hasMachoZeroFillDirective() &&
582 TheSection->isVirtualSection()) {
583 if (Size == 0)
584 Size = 1; // zerofill of 0 bytes is undefined.
585 emitLinkage(GV, GVSym);
586 // .zerofill __DATA, __bss, _foo, 400, 5
587 OutStreamer->emitZerofill(TheSection, GVSym, Size, Alignment.value());
588 return;
589 }
590
591 // If this is a BSS local symbol and we are emitting in the BSS
592 // section use .lcomm/.comm directive.
593 if (GVKind.isBSSLocal() &&
594 getObjFileLowering().getBSSSection() == TheSection) {
595 if (Size == 0)
596 Size = 1; // .comm Foo, 0 is undefined, avoid it.
597
598 // Use .lcomm only if it supports user-specified alignment.
599 // Otherwise, while it would still be correct to use .lcomm in some
600 // cases (e.g. when Align == 1), the external assembler might enfore
601 // some -unknown- default alignment behavior, which could cause
602 // spurious differences between external and integrated assembler.
603 // Prefer to simply fall back to .local / .comm in this case.
604 if (MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
605 // .lcomm _foo, 42
606 OutStreamer->emitLocalCommonSymbol(GVSym, Size, Alignment.value());
607 return;
608 }
609
610 // .local _foo
611 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Local);
612 // .comm _foo, 42, 4
613 const bool SupportsAlignment =
614 getObjFileLowering().getCommDirectiveSupportsAlignment();
615 OutStreamer->emitCommonSymbol(GVSym, Size,
616 SupportsAlignment ? Alignment.value() : 0);
617 return;
618 }
619
620 // Handle thread local data for mach-o which requires us to output an
621 // additional structure of data and mangle the original symbol so that we
622 // can reference it later.
623 //
624 // TODO: This should become an "emit thread local global" method on TLOF.
625 // All of this macho specific stuff should be sunk down into TLOFMachO and
626 // stuff like "TLSExtraDataSection" should no longer be part of the parent
627 // TLOF class. This will also make it more obvious that stuff like
628 // MCStreamer::EmitTBSSSymbol is macho specific and only called from macho
629 // specific code.
630 if (GVKind.isThreadLocal() && MAI->hasMachoTBSSDirective()) {
631 // Emit the .tbss symbol
632 MCSymbol *MangSym =
633 OutContext.getOrCreateSymbol(GVSym->getName() + Twine("$tlv$init"));
634
635 if (GVKind.isThreadBSS()) {
636 TheSection = getObjFileLowering().getTLSBSSSection();
637 OutStreamer->emitTBSSSymbol(TheSection, MangSym, Size, Alignment.value());
638 } else if (GVKind.isThreadData()) {
639 OutStreamer->SwitchSection(TheSection);
640
641 emitAlignment(Alignment, GV);
642 OutStreamer->emitLabel(MangSym);
643
644 emitGlobalConstant(GV->getParent()->getDataLayout(),
645 GV->getInitializer());
646 }
647
648 OutStreamer->AddBlankLine();
649
650 // Emit the variable struct for the runtime.
651 MCSection *TLVSect = getObjFileLowering().getTLSExtraDataSection();
652
653 OutStreamer->SwitchSection(TLVSect);
654 // Emit the linkage here.
655 emitLinkage(GV, GVSym);
656 OutStreamer->emitLabel(GVSym);
657
658 // Three pointers in size:
659 // - __tlv_bootstrap - used to make sure support exists
660 // - spare pointer, used when mapped by the runtime
661 // - pointer to mangled symbol above with initializer
662 unsigned PtrSize = DL.getPointerTypeSize(GV->getType());
663 OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("_tlv_bootstrap"),
664 PtrSize);
665 OutStreamer->emitIntValue(0, PtrSize);
666 OutStreamer->emitSymbolValue(MangSym, PtrSize);
667
668 OutStreamer->AddBlankLine();
669 return;
670 }
671
672 MCSymbol *EmittedInitSym = GVSym;
673
674 OutStreamer->SwitchSection(TheSection);
675
676 emitLinkage(GV, EmittedInitSym);
677 emitAlignment(Alignment, GV);
678
679 OutStreamer->emitLabel(EmittedInitSym);
680 MCSymbol *LocalAlias = getSymbolPreferLocal(*GV);
681 if (LocalAlias != EmittedInitSym)
682 OutStreamer->emitLabel(LocalAlias);
683
684 emitGlobalConstant(GV->getParent()->getDataLayout(), GV->getInitializer());
685
686 if (MAI->hasDotTypeDotSizeDirective())
687 // .size foo, 42
688 OutStreamer->emitELFSize(EmittedInitSym,
689 MCConstantExpr::create(Size, OutContext));
690
691 OutStreamer->AddBlankLine();
692 }
693
694 /// Emit the directive and value for debug thread local expression
695 ///
696 /// \p Value - The value to emit.
697 /// \p Size - The size of the integer (in bytes) to emit.
emitDebugValue(const MCExpr * Value,unsigned Size) const698 void AsmPrinter::emitDebugValue(const MCExpr *Value, unsigned Size) const {
699 OutStreamer->emitValue(Value, Size);
700 }
701
emitFunctionHeaderComment()702 void AsmPrinter::emitFunctionHeaderComment() {}
703
704 /// EmitFunctionHeader - This method emits the header for the current
705 /// function.
emitFunctionHeader()706 void AsmPrinter::emitFunctionHeader() {
707 const Function &F = MF->getFunction();
708
709 if (isVerbose())
710 OutStreamer->GetCommentOS()
711 << "-- Begin function "
712 << GlobalValue::dropLLVMManglingEscape(F.getName()) << '\n';
713
714 // Print out constants referenced by the function
715 emitConstantPool();
716
717 // Print the 'header' of function.
718 // If basic block sections are desired, explicitly request a unique section
719 // for this function's entry block.
720 if (MF->front().isBeginSection())
721 MF->setSection(getObjFileLowering().getUniqueSectionForFunction(F, TM));
722 else
723 MF->setSection(getObjFileLowering().SectionForGlobal(&F, TM));
724 OutStreamer->SwitchSection(MF->getSection());
725
726 if (!MAI->hasVisibilityOnlyWithLinkage())
727 emitVisibility(CurrentFnSym, F.getVisibility());
728
729 if (MAI->needsFunctionDescriptors())
730 emitLinkage(&F, CurrentFnDescSym);
731
732 emitLinkage(&F, CurrentFnSym);
733 if (MAI->hasFunctionAlignment())
734 emitAlignment(MF->getAlignment(), &F);
735
736 if (MAI->hasDotTypeDotSizeDirective())
737 OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
738
739 if (F.hasFnAttribute(Attribute::Cold))
740 OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_Cold);
741
742 if (isVerbose()) {
743 F.printAsOperand(OutStreamer->GetCommentOS(),
744 /*PrintType=*/false, F.getParent());
745 emitFunctionHeaderComment();
746 OutStreamer->GetCommentOS() << '\n';
747 }
748
749 // Emit the prefix data.
750 if (F.hasPrefixData()) {
751 if (MAI->hasSubsectionsViaSymbols()) {
752 // Preserving prefix data on platforms which use subsections-via-symbols
753 // is a bit tricky. Here we introduce a symbol for the prefix data
754 // and use the .alt_entry attribute to mark the function's real entry point
755 // as an alternative entry point to the prefix-data symbol.
756 MCSymbol *PrefixSym = OutContext.createLinkerPrivateTempSymbol();
757 OutStreamer->emitLabel(PrefixSym);
758
759 emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
760
761 // Emit an .alt_entry directive for the actual function symbol.
762 OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_AltEntry);
763 } else {
764 emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
765 }
766 }
767
768 // Emit M NOPs for -fpatchable-function-entry=N,M where M>0. We arbitrarily
769 // place prefix data before NOPs.
770 unsigned PatchableFunctionPrefix = 0;
771 unsigned PatchableFunctionEntry = 0;
772 (void)F.getFnAttribute("patchable-function-prefix")
773 .getValueAsString()
774 .getAsInteger(10, PatchableFunctionPrefix);
775 (void)F.getFnAttribute("patchable-function-entry")
776 .getValueAsString()
777 .getAsInteger(10, PatchableFunctionEntry);
778 if (PatchableFunctionPrefix) {
779 CurrentPatchableFunctionEntrySym =
780 OutContext.createLinkerPrivateTempSymbol();
781 OutStreamer->emitLabel(CurrentPatchableFunctionEntrySym);
782 emitNops(PatchableFunctionPrefix);
783 } else if (PatchableFunctionEntry) {
784 // May be reassigned when emitting the body, to reference the label after
785 // the initial BTI (AArch64) or endbr32/endbr64 (x86).
786 CurrentPatchableFunctionEntrySym = CurrentFnBegin;
787 }
788
789 // Emit the function descriptor. This is a virtual function to allow targets
790 // to emit their specific function descriptor. Right now it is only used by
791 // the AIX target. The PowerPC 64-bit V1 ELF target also uses function
792 // descriptors and should be converted to use this hook as well.
793 if (MAI->needsFunctionDescriptors())
794 emitFunctionDescriptor();
795
796 // Emit the CurrentFnSym. This is a virtual function to allow targets to do
797 // their wild and crazy things as required.
798 emitFunctionEntryLabel();
799
800 // If the function had address-taken blocks that got deleted, then we have
801 // references to the dangling symbols. Emit them at the start of the function
802 // so that we don't get references to undefined symbols.
803 std::vector<MCSymbol*> DeadBlockSyms;
804 MMI->takeDeletedSymbolsForFunction(&F, DeadBlockSyms);
805 for (unsigned i = 0, e = DeadBlockSyms.size(); i != e; ++i) {
806 OutStreamer->AddComment("Address taken block that was later removed");
807 OutStreamer->emitLabel(DeadBlockSyms[i]);
808 }
809
810 if (CurrentFnBegin) {
811 if (MAI->useAssignmentForEHBegin()) {
812 MCSymbol *CurPos = OutContext.createTempSymbol();
813 OutStreamer->emitLabel(CurPos);
814 OutStreamer->emitAssignment(CurrentFnBegin,
815 MCSymbolRefExpr::create(CurPos, OutContext));
816 } else {
817 OutStreamer->emitLabel(CurrentFnBegin);
818 }
819 }
820
821 // Emit pre-function debug and/or EH information.
822 for (const HandlerInfo &HI : Handlers) {
823 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
824 HI.TimerGroupDescription, TimePassesIsEnabled);
825 HI.Handler->beginFunction(MF);
826 }
827
828 // Emit the prologue data.
829 if (F.hasPrologueData())
830 emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrologueData());
831 }
832
833 /// EmitFunctionEntryLabel - Emit the label that is the entrypoint for the
834 /// function. This can be overridden by targets as required to do custom stuff.
emitFunctionEntryLabel()835 void AsmPrinter::emitFunctionEntryLabel() {
836 CurrentFnSym->redefineIfPossible();
837
838 // The function label could have already been emitted if two symbols end up
839 // conflicting due to asm renaming. Detect this and emit an error.
840 if (CurrentFnSym->isVariable())
841 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
842 "' is a protected alias");
843
844 OutStreamer->emitLabel(CurrentFnSym);
845
846 if (TM.getTargetTriple().isOSBinFormatELF()) {
847 MCSymbol *Sym = getSymbolPreferLocal(MF->getFunction());
848 if (Sym != CurrentFnSym)
849 OutStreamer->emitLabel(Sym);
850 }
851 }
852
853 /// emitComments - Pretty-print comments for instructions.
emitComments(const MachineInstr & MI,raw_ostream & CommentOS)854 static void emitComments(const MachineInstr &MI, raw_ostream &CommentOS) {
855 const MachineFunction *MF = MI.getMF();
856 const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
857
858 // Check for spills and reloads
859
860 // We assume a single instruction only has a spill or reload, not
861 // both.
862 Optional<unsigned> Size;
863 if ((Size = MI.getRestoreSize(TII))) {
864 CommentOS << *Size << "-byte Reload\n";
865 } else if ((Size = MI.getFoldedRestoreSize(TII))) {
866 if (*Size) {
867 if (*Size == unsigned(MemoryLocation::UnknownSize))
868 CommentOS << "Unknown-size Folded Reload\n";
869 else
870 CommentOS << *Size << "-byte Folded Reload\n";
871 }
872 } else if ((Size = MI.getSpillSize(TII))) {
873 CommentOS << *Size << "-byte Spill\n";
874 } else if ((Size = MI.getFoldedSpillSize(TII))) {
875 if (*Size) {
876 if (*Size == unsigned(MemoryLocation::UnknownSize))
877 CommentOS << "Unknown-size Folded Spill\n";
878 else
879 CommentOS << *Size << "-byte Folded Spill\n";
880 }
881 }
882
883 // Check for spill-induced copies
884 if (MI.getAsmPrinterFlag(MachineInstr::ReloadReuse))
885 CommentOS << " Reload Reuse\n";
886 }
887
888 /// emitImplicitDef - This method emits the specified machine instruction
889 /// that is an implicit def.
emitImplicitDef(const MachineInstr * MI) const890 void AsmPrinter::emitImplicitDef(const MachineInstr *MI) const {
891 Register RegNo = MI->getOperand(0).getReg();
892
893 SmallString<128> Str;
894 raw_svector_ostream OS(Str);
895 OS << "implicit-def: "
896 << printReg(RegNo, MF->getSubtarget().getRegisterInfo());
897
898 OutStreamer->AddComment(OS.str());
899 OutStreamer->AddBlankLine();
900 }
901
emitKill(const MachineInstr * MI,AsmPrinter & AP)902 static void emitKill(const MachineInstr *MI, AsmPrinter &AP) {
903 std::string Str;
904 raw_string_ostream OS(Str);
905 OS << "kill:";
906 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
907 const MachineOperand &Op = MI->getOperand(i);
908 assert(Op.isReg() && "KILL instruction must have only register operands");
909 OS << ' ' << (Op.isDef() ? "def " : "killed ")
910 << printReg(Op.getReg(), AP.MF->getSubtarget().getRegisterInfo());
911 }
912 AP.OutStreamer->AddComment(OS.str());
913 AP.OutStreamer->AddBlankLine();
914 }
915
916 /// emitDebugValueComment - This method handles the target-independent form
917 /// of DBG_VALUE, returning true if it was able to do so. A false return
918 /// means the target will need to handle MI in EmitInstruction.
emitDebugValueComment(const MachineInstr * MI,AsmPrinter & AP)919 static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
920 // This code handles only the 4-operand target-independent form.
921 if (MI->isNonListDebugValue() && MI->getNumOperands() != 4)
922 return false;
923
924 SmallString<128> Str;
925 raw_svector_ostream OS(Str);
926 OS << "DEBUG_VALUE: ";
927
928 const DILocalVariable *V = MI->getDebugVariable();
929 if (auto *SP = dyn_cast<DISubprogram>(V->getScope())) {
930 StringRef Name = SP->getName();
931 if (!Name.empty())
932 OS << Name << ":";
933 }
934 OS << V->getName();
935 OS << " <- ";
936
937 const DIExpression *Expr = MI->getDebugExpression();
938 if (Expr->getNumElements()) {
939 OS << '[';
940 ListSeparator LS;
941 for (auto Op : Expr->expr_ops()) {
942 OS << LS << dwarf::OperationEncodingString(Op.getOp());
943 for (unsigned I = 0; I < Op.getNumArgs(); ++I)
944 OS << ' ' << Op.getArg(I);
945 }
946 OS << "] ";
947 }
948
949 // Register or immediate value. Register 0 means undef.
950 for (const MachineOperand &Op : MI->debug_operands()) {
951 if (&Op != MI->debug_operands().begin())
952 OS << ", ";
953 switch (Op.getType()) {
954 case MachineOperand::MO_FPImmediate: {
955 APFloat APF = APFloat(Op.getFPImm()->getValueAPF());
956 Type *ImmTy = Op.getFPImm()->getType();
957 if (ImmTy->isBFloatTy() || ImmTy->isHalfTy() || ImmTy->isFloatTy() ||
958 ImmTy->isDoubleTy()) {
959 OS << APF.convertToDouble();
960 } else {
961 // There is no good way to print long double. Convert a copy to
962 // double. Ah well, it's only a comment.
963 bool ignored;
964 APF.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
965 &ignored);
966 OS << "(long double) " << APF.convertToDouble();
967 }
968 break;
969 }
970 case MachineOperand::MO_Immediate: {
971 OS << Op.getImm();
972 break;
973 }
974 case MachineOperand::MO_CImmediate: {
975 Op.getCImm()->getValue().print(OS, false /*isSigned*/);
976 break;
977 }
978 case MachineOperand::MO_TargetIndex: {
979 OS << "!target-index(" << Op.getIndex() << "," << Op.getOffset() << ")";
980 // NOTE: Want this comment at start of line, don't emit with AddComment.
981 AP.OutStreamer->emitRawComment(OS.str());
982 break;
983 }
984 case MachineOperand::MO_Register:
985 case MachineOperand::MO_FrameIndex: {
986 Register Reg;
987 Optional<StackOffset> Offset;
988 if (Op.isReg()) {
989 Reg = Op.getReg();
990 } else {
991 const TargetFrameLowering *TFI =
992 AP.MF->getSubtarget().getFrameLowering();
993 Offset = TFI->getFrameIndexReference(*AP.MF, Op.getIndex(), Reg);
994 }
995 if (!Reg) {
996 // Suppress offset, it is not meaningful here.
997 OS << "undef";
998 break;
999 }
1000 // The second operand is only an offset if it's an immediate.
1001 if (MI->isIndirectDebugValue())
1002 Offset = StackOffset::getFixed(MI->getDebugOffset().getImm());
1003 if (Offset)
1004 OS << '[';
1005 OS << printReg(Reg, AP.MF->getSubtarget().getRegisterInfo());
1006 if (Offset)
1007 OS << '+' << Offset->getFixed() << ']';
1008 break;
1009 }
1010 default:
1011 llvm_unreachable("Unknown operand type");
1012 }
1013 }
1014
1015 // NOTE: Want this comment at start of line, don't emit with AddComment.
1016 AP.OutStreamer->emitRawComment(OS.str());
1017 return true;
1018 }
1019
1020 /// This method handles the target-independent form of DBG_LABEL, returning
1021 /// true if it was able to do so. A false return means the target will need
1022 /// to handle MI in EmitInstruction.
emitDebugLabelComment(const MachineInstr * MI,AsmPrinter & AP)1023 static bool emitDebugLabelComment(const MachineInstr *MI, AsmPrinter &AP) {
1024 if (MI->getNumOperands() != 1)
1025 return false;
1026
1027 SmallString<128> Str;
1028 raw_svector_ostream OS(Str);
1029 OS << "DEBUG_LABEL: ";
1030
1031 const DILabel *V = MI->getDebugLabel();
1032 if (auto *SP = dyn_cast<DISubprogram>(
1033 V->getScope()->getNonLexicalBlockFileScope())) {
1034 StringRef Name = SP->getName();
1035 if (!Name.empty())
1036 OS << Name << ":";
1037 }
1038 OS << V->getName();
1039
1040 // NOTE: Want this comment at start of line, don't emit with AddComment.
1041 AP.OutStreamer->emitRawComment(OS.str());
1042 return true;
1043 }
1044
1045 AsmPrinter::CFISection
getFunctionCFISectionType(const Function & F) const1046 AsmPrinter::getFunctionCFISectionType(const Function &F) const {
1047 // Ignore functions that won't get emitted.
1048 if (F.isDeclarationForLinker())
1049 return CFISection::None;
1050
1051 if (MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI &&
1052 F.needsUnwindTableEntry())
1053 return CFISection::EH;
1054
1055 if (MMI->hasDebugInfo() || TM.Options.ForceDwarfFrameSection)
1056 return CFISection::Debug;
1057
1058 return CFISection::None;
1059 }
1060
1061 AsmPrinter::CFISection
getFunctionCFISectionType(const MachineFunction & MF) const1062 AsmPrinter::getFunctionCFISectionType(const MachineFunction &MF) const {
1063 return getFunctionCFISectionType(MF.getFunction());
1064 }
1065
needsSEHMoves()1066 bool AsmPrinter::needsSEHMoves() {
1067 return MAI->usesWindowsCFI() && MF->getFunction().needsUnwindTableEntry();
1068 }
1069
needsCFIForDebug() const1070 bool AsmPrinter::needsCFIForDebug() const {
1071 return MAI->getExceptionHandlingType() == ExceptionHandling::None &&
1072 MAI->doesUseCFIForDebug() && ModuleCFISection == CFISection::Debug;
1073 }
1074
emitCFIInstruction(const MachineInstr & MI)1075 void AsmPrinter::emitCFIInstruction(const MachineInstr &MI) {
1076 ExceptionHandling ExceptionHandlingType = MAI->getExceptionHandlingType();
1077 if (!needsCFIForDebug() &&
1078 ExceptionHandlingType != ExceptionHandling::DwarfCFI &&
1079 ExceptionHandlingType != ExceptionHandling::ARM)
1080 return;
1081
1082 if (getFunctionCFISectionType(*MF) == CFISection::None)
1083 return;
1084
1085 // If there is no "real" instruction following this CFI instruction, skip
1086 // emitting it; it would be beyond the end of the function's FDE range.
1087 auto *MBB = MI.getParent();
1088 auto I = std::next(MI.getIterator());
1089 while (I != MBB->end() && I->isTransient())
1090 ++I;
1091 if (I == MBB->instr_end() &&
1092 MBB->getReverseIterator() == MBB->getParent()->rbegin())
1093 return;
1094
1095 const std::vector<MCCFIInstruction> &Instrs = MF->getFrameInstructions();
1096 unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
1097 const MCCFIInstruction &CFI = Instrs[CFIIndex];
1098 emitCFIInstruction(CFI);
1099 }
1100
emitFrameAlloc(const MachineInstr & MI)1101 void AsmPrinter::emitFrameAlloc(const MachineInstr &MI) {
1102 // The operands are the MCSymbol and the frame offset of the allocation.
1103 MCSymbol *FrameAllocSym = MI.getOperand(0).getMCSymbol();
1104 int FrameOffset = MI.getOperand(1).getImm();
1105
1106 // Emit a symbol assignment.
1107 OutStreamer->emitAssignment(FrameAllocSym,
1108 MCConstantExpr::create(FrameOffset, OutContext));
1109 }
1110
1111 /// Returns the BB metadata to be emitted in the .llvm_bb_addr_map section for a
1112 /// given basic block. This can be used to capture more precise profile
1113 /// information. We use the last 4 bits (LSBs) to encode the following
1114 /// information:
1115 /// * (1): set if return block (ret or tail call).
1116 /// * (2): set if ends with a tail call.
1117 /// * (3): set if exception handling (EH) landing pad.
1118 /// * (4): set if the block can fall through to its next.
1119 /// The remaining bits are zero.
getBBAddrMapMetadata(const MachineBasicBlock & MBB)1120 static unsigned getBBAddrMapMetadata(const MachineBasicBlock &MBB) {
1121 const TargetInstrInfo *TII = MBB.getParent()->getSubtarget().getInstrInfo();
1122 return ((unsigned)MBB.isReturnBlock()) |
1123 ((!MBB.empty() && TII->isTailCall(MBB.back())) << 1) |
1124 (MBB.isEHPad() << 2) |
1125 (const_cast<MachineBasicBlock &>(MBB).canFallThrough() << 3);
1126 }
1127
emitBBAddrMapSection(const MachineFunction & MF)1128 void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
1129 MCSection *BBAddrMapSection =
1130 getObjFileLowering().getBBAddrMapSection(*MF.getSection());
1131 assert(BBAddrMapSection && ".llvm_bb_addr_map section is not initialized.");
1132
1133 const MCSymbol *FunctionSymbol = getFunctionBegin();
1134
1135 OutStreamer->PushSection();
1136 OutStreamer->SwitchSection(BBAddrMapSection);
1137 OutStreamer->emitSymbolValue(FunctionSymbol, getPointerSize());
1138 // Emit the total number of basic blocks in this function.
1139 OutStreamer->emitULEB128IntValue(MF.size());
1140 // Emit BB Information for each basic block in the funciton.
1141 for (const MachineBasicBlock &MBB : MF) {
1142 const MCSymbol *MBBSymbol =
1143 MBB.isEntryBlock() ? FunctionSymbol : MBB.getSymbol();
1144 // Emit the basic block offset.
1145 emitLabelDifferenceAsULEB128(MBBSymbol, FunctionSymbol);
1146 // Emit the basic block size. When BBs have alignments, their size cannot
1147 // always be computed from their offsets.
1148 emitLabelDifferenceAsULEB128(MBB.getEndSymbol(), MBBSymbol);
1149 OutStreamer->emitULEB128IntValue(getBBAddrMapMetadata(MBB));
1150 }
1151 OutStreamer->PopSection();
1152 }
1153
emitPseudoProbe(const MachineInstr & MI)1154 void AsmPrinter::emitPseudoProbe(const MachineInstr &MI) {
1155 auto GUID = MI.getOperand(0).getImm();
1156 auto Index = MI.getOperand(1).getImm();
1157 auto Type = MI.getOperand(2).getImm();
1158 auto Attr = MI.getOperand(3).getImm();
1159 DILocation *DebugLoc = MI.getDebugLoc();
1160 PP->emitPseudoProbe(GUID, Index, Type, Attr, DebugLoc);
1161 }
1162
emitStackSizeSection(const MachineFunction & MF)1163 void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
1164 if (!MF.getTarget().Options.EmitStackSizeSection)
1165 return;
1166
1167 MCSection *StackSizeSection =
1168 getObjFileLowering().getStackSizesSection(*getCurrentSection());
1169 if (!StackSizeSection)
1170 return;
1171
1172 const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
1173 // Don't emit functions with dynamic stack allocations.
1174 if (FrameInfo.hasVarSizedObjects())
1175 return;
1176
1177 OutStreamer->PushSection();
1178 OutStreamer->SwitchSection(StackSizeSection);
1179
1180 const MCSymbol *FunctionSymbol = getFunctionBegin();
1181 uint64_t StackSize = FrameInfo.getStackSize();
1182 OutStreamer->emitSymbolValue(FunctionSymbol, TM.getProgramPointerSize());
1183 OutStreamer->emitULEB128IntValue(StackSize);
1184
1185 OutStreamer->PopSection();
1186 }
1187
emitStackUsage(const MachineFunction & MF)1188 void AsmPrinter::emitStackUsage(const MachineFunction &MF) {
1189 const std::string &OutputFilename = MF.getTarget().Options.StackUsageOutput;
1190
1191 // OutputFilename empty implies -fstack-usage is not passed.
1192 if (OutputFilename.empty())
1193 return;
1194
1195 const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
1196 uint64_t StackSize = FrameInfo.getStackSize();
1197
1198 if (StackUsageStream == nullptr) {
1199 std::error_code EC;
1200 StackUsageStream =
1201 std::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::OF_Text);
1202 if (EC) {
1203 errs() << "Could not open file: " << EC.message();
1204 return;
1205 }
1206 }
1207
1208 *StackUsageStream << MF.getFunction().getParent()->getName();
1209 if (const DISubprogram *DSP = MF.getFunction().getSubprogram())
1210 *StackUsageStream << ':' << DSP->getLine();
1211
1212 *StackUsageStream << ':' << MF.getName() << '\t' << StackSize << '\t';
1213 if (FrameInfo.hasVarSizedObjects())
1214 *StackUsageStream << "dynamic\n";
1215 else
1216 *StackUsageStream << "static\n";
1217 }
1218
needFuncLabelsForEHOrDebugInfo(const MachineFunction & MF)1219 static bool needFuncLabelsForEHOrDebugInfo(const MachineFunction &MF) {
1220 MachineModuleInfo &MMI = MF.getMMI();
1221 if (!MF.getLandingPads().empty() || MF.hasEHFunclets() || MMI.hasDebugInfo())
1222 return true;
1223
1224 // We might emit an EH table that uses function begin and end labels even if
1225 // we don't have any landingpads.
1226 if (!MF.getFunction().hasPersonalityFn())
1227 return false;
1228 return !isNoOpWithoutInvoke(
1229 classifyEHPersonality(MF.getFunction().getPersonalityFn()));
1230 }
1231
1232 /// EmitFunctionBody - This method emits the body and trailer for a
1233 /// function.
emitFunctionBody()1234 void AsmPrinter::emitFunctionBody() {
1235 emitFunctionHeader();
1236
1237 // Emit target-specific gunk before the function body.
1238 emitFunctionBodyStart();
1239
1240 if (isVerbose()) {
1241 // Get MachineDominatorTree or compute it on the fly if it's unavailable
1242 MDT = getAnalysisIfAvailable<MachineDominatorTree>();
1243 if (!MDT) {
1244 OwnedMDT = std::make_unique<MachineDominatorTree>();
1245 OwnedMDT->getBase().recalculate(*MF);
1246 MDT = OwnedMDT.get();
1247 }
1248
1249 // Get MachineLoopInfo or compute it on the fly if it's unavailable
1250 MLI = getAnalysisIfAvailable<MachineLoopInfo>();
1251 if (!MLI) {
1252 OwnedMLI = std::make_unique<MachineLoopInfo>();
1253 OwnedMLI->getBase().analyze(MDT->getBase());
1254 MLI = OwnedMLI.get();
1255 }
1256 }
1257
1258 // Print out code for the function.
1259 bool HasAnyRealCode = false;
1260 int NumInstsInFunction = 0;
1261
1262 bool CanDoExtraAnalysis = ORE->allowExtraAnalysis(DEBUG_TYPE);
1263 for (auto &MBB : *MF) {
1264 // Print a label for the basic block.
1265 emitBasicBlockStart(MBB);
1266 DenseMap<StringRef, unsigned> MnemonicCounts;
1267 for (auto &MI : MBB) {
1268 // Print the assembly for the instruction.
1269 if (!MI.isPosition() && !MI.isImplicitDef() && !MI.isKill() &&
1270 !MI.isDebugInstr()) {
1271 HasAnyRealCode = true;
1272 ++NumInstsInFunction;
1273 }
1274
1275 // If there is a pre-instruction symbol, emit a label for it here.
1276 if (MCSymbol *S = MI.getPreInstrSymbol())
1277 OutStreamer->emitLabel(S);
1278
1279 for (const HandlerInfo &HI : Handlers) {
1280 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1281 HI.TimerGroupDescription, TimePassesIsEnabled);
1282 HI.Handler->beginInstruction(&MI);
1283 }
1284
1285 if (isVerbose())
1286 emitComments(MI, OutStreamer->GetCommentOS());
1287
1288 switch (MI.getOpcode()) {
1289 case TargetOpcode::CFI_INSTRUCTION:
1290 emitCFIInstruction(MI);
1291 break;
1292 case TargetOpcode::LOCAL_ESCAPE:
1293 emitFrameAlloc(MI);
1294 break;
1295 case TargetOpcode::ANNOTATION_LABEL:
1296 case TargetOpcode::EH_LABEL:
1297 case TargetOpcode::GC_LABEL:
1298 OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol());
1299 break;
1300 case TargetOpcode::INLINEASM:
1301 case TargetOpcode::INLINEASM_BR:
1302 emitInlineAsm(&MI);
1303 break;
1304 case TargetOpcode::DBG_VALUE:
1305 case TargetOpcode::DBG_VALUE_LIST:
1306 if (isVerbose()) {
1307 if (!emitDebugValueComment(&MI, *this))
1308 emitInstruction(&MI);
1309 }
1310 break;
1311 case TargetOpcode::DBG_INSTR_REF:
1312 // This instruction reference will have been resolved to a machine
1313 // location, and a nearby DBG_VALUE created. We can safely ignore
1314 // the instruction reference.
1315 break;
1316 case TargetOpcode::DBG_LABEL:
1317 if (isVerbose()) {
1318 if (!emitDebugLabelComment(&MI, *this))
1319 emitInstruction(&MI);
1320 }
1321 break;
1322 case TargetOpcode::IMPLICIT_DEF:
1323 if (isVerbose()) emitImplicitDef(&MI);
1324 break;
1325 case TargetOpcode::KILL:
1326 if (isVerbose()) emitKill(&MI, *this);
1327 break;
1328 case TargetOpcode::PSEUDO_PROBE:
1329 emitPseudoProbe(MI);
1330 break;
1331 default:
1332 emitInstruction(&MI);
1333 if (CanDoExtraAnalysis) {
1334 MCInst MCI;
1335 MCI.setOpcode(MI.getOpcode());
1336 auto Name = OutStreamer->getMnemonic(MCI);
1337 auto I = MnemonicCounts.insert({Name, 0u});
1338 I.first->second++;
1339 }
1340 break;
1341 }
1342
1343 // If there is a post-instruction symbol, emit a label for it here.
1344 if (MCSymbol *S = MI.getPostInstrSymbol())
1345 OutStreamer->emitLabel(S);
1346
1347 for (const HandlerInfo &HI : Handlers) {
1348 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1349 HI.TimerGroupDescription, TimePassesIsEnabled);
1350 HI.Handler->endInstruction();
1351 }
1352 }
1353
1354 // We must emit temporary symbol for the end of this basic block, if either
1355 // we have BBLabels enabled or if this basic blocks marks the end of a
1356 // section (except the section containing the entry basic block as the end
1357 // symbol for that section is CurrentFnEnd).
1358 if (MF->hasBBLabels() ||
1359 (MAI->hasDotTypeDotSizeDirective() && MBB.isEndSection() &&
1360 !MBB.sameSection(&MF->front())))
1361 OutStreamer->emitLabel(MBB.getEndSymbol());
1362
1363 if (MBB.isEndSection()) {
1364 // The size directive for the section containing the entry block is
1365 // handled separately by the function section.
1366 if (!MBB.sameSection(&MF->front())) {
1367 if (MAI->hasDotTypeDotSizeDirective()) {
1368 // Emit the size directive for the basic block section.
1369 const MCExpr *SizeExp = MCBinaryExpr::createSub(
1370 MCSymbolRefExpr::create(MBB.getEndSymbol(), OutContext),
1371 MCSymbolRefExpr::create(CurrentSectionBeginSym, OutContext),
1372 OutContext);
1373 OutStreamer->emitELFSize(CurrentSectionBeginSym, SizeExp);
1374 }
1375 MBBSectionRanges[MBB.getSectionIDNum()] =
1376 MBBSectionRange{CurrentSectionBeginSym, MBB.getEndSymbol()};
1377 }
1378 }
1379 emitBasicBlockEnd(MBB);
1380
1381 if (CanDoExtraAnalysis) {
1382 // Skip empty blocks.
1383 if (MBB.empty())
1384 continue;
1385
1386 MachineOptimizationRemarkAnalysis R(DEBUG_TYPE, "InstructionMix",
1387 MBB.begin()->getDebugLoc(), &MBB);
1388
1389 // Generate instruction mix remark. First, sort counts in descending order
1390 // by count and name.
1391 SmallVector<std::pair<StringRef, unsigned>, 128> MnemonicVec;
1392 for (auto &KV : MnemonicCounts)
1393 MnemonicVec.emplace_back(KV.first, KV.second);
1394
1395 sort(MnemonicVec, [](const std::pair<StringRef, unsigned> &A,
1396 const std::pair<StringRef, unsigned> &B) {
1397 if (A.second > B.second)
1398 return true;
1399 if (A.second == B.second)
1400 return StringRef(A.first) < StringRef(B.first);
1401 return false;
1402 });
1403 R << "BasicBlock: " << ore::NV("BasicBlock", MBB.getName()) << "\n";
1404 for (auto &KV : MnemonicVec) {
1405 auto Name = (Twine("INST_") + KV.first.trim()).str();
1406 R << KV.first << ": " << ore::NV(Name, KV.second) << "\n";
1407 }
1408 ORE->emit(R);
1409 }
1410 }
1411
1412 EmittedInsts += NumInstsInFunction;
1413 MachineOptimizationRemarkAnalysis R(DEBUG_TYPE, "InstructionCount",
1414 MF->getFunction().getSubprogram(),
1415 &MF->front());
1416 R << ore::NV("NumInstructions", NumInstsInFunction)
1417 << " instructions in function";
1418 ORE->emit(R);
1419
1420 // If the function is empty and the object file uses .subsections_via_symbols,
1421 // then we need to emit *something* to the function body to prevent the
1422 // labels from collapsing together. Just emit a noop.
1423 // Similarly, don't emit empty functions on Windows either. It can lead to
1424 // duplicate entries (two functions with the same RVA) in the Guard CF Table
1425 // after linking, causing the kernel not to load the binary:
1426 // https://developercommunity.visualstudio.com/content/problem/45366/vc-linker-creates-invalid-dll-with-clang-cl.html
1427 // FIXME: Hide this behind some API in e.g. MCAsmInfo or MCTargetStreamer.
1428 const Triple &TT = TM.getTargetTriple();
1429 if (!HasAnyRealCode && (MAI->hasSubsectionsViaSymbols() ||
1430 (TT.isOSWindows() && TT.isOSBinFormatCOFF()))) {
1431 MCInst Noop = MF->getSubtarget().getInstrInfo()->getNop();
1432
1433 // Targets can opt-out of emitting the noop here by leaving the opcode
1434 // unspecified.
1435 if (Noop.getOpcode()) {
1436 OutStreamer->AddComment("avoids zero-length function");
1437 emitNops(1);
1438 }
1439 }
1440
1441 // Switch to the original section in case basic block sections was used.
1442 OutStreamer->SwitchSection(MF->getSection());
1443
1444 const Function &F = MF->getFunction();
1445 for (const auto &BB : F) {
1446 if (!BB.hasAddressTaken())
1447 continue;
1448 MCSymbol *Sym = GetBlockAddressSymbol(&BB);
1449 if (Sym->isDefined())
1450 continue;
1451 OutStreamer->AddComment("Address of block that was removed by CodeGen");
1452 OutStreamer->emitLabel(Sym);
1453 }
1454
1455 // Emit target-specific gunk after the function body.
1456 emitFunctionBodyEnd();
1457
1458 if (needFuncLabelsForEHOrDebugInfo(*MF) ||
1459 MAI->hasDotTypeDotSizeDirective()) {
1460 // Create a symbol for the end of function.
1461 CurrentFnEnd = createTempSymbol("func_end");
1462 OutStreamer->emitLabel(CurrentFnEnd);
1463 }
1464
1465 // If the target wants a .size directive for the size of the function, emit
1466 // it.
1467 if (MAI->hasDotTypeDotSizeDirective()) {
1468 // We can get the size as difference between the function label and the
1469 // temp label.
1470 const MCExpr *SizeExp = MCBinaryExpr::createSub(
1471 MCSymbolRefExpr::create(CurrentFnEnd, OutContext),
1472 MCSymbolRefExpr::create(CurrentFnSymForSize, OutContext), OutContext);
1473 OutStreamer->emitELFSize(CurrentFnSym, SizeExp);
1474 }
1475
1476 for (const HandlerInfo &HI : Handlers) {
1477 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1478 HI.TimerGroupDescription, TimePassesIsEnabled);
1479 HI.Handler->markFunctionEnd();
1480 }
1481
1482 MBBSectionRanges[MF->front().getSectionIDNum()] =
1483 MBBSectionRange{CurrentFnBegin, CurrentFnEnd};
1484
1485 // Print out jump tables referenced by the function.
1486 emitJumpTableInfo();
1487
1488 // Emit post-function debug and/or EH information.
1489 for (const HandlerInfo &HI : Handlers) {
1490 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1491 HI.TimerGroupDescription, TimePassesIsEnabled);
1492 HI.Handler->endFunction(MF);
1493 }
1494
1495 // Emit section containing BB address offsets and their metadata, when
1496 // BB labels are requested for this function. Skip empty functions.
1497 if (MF->hasBBLabels() && HasAnyRealCode)
1498 emitBBAddrMapSection(*MF);
1499
1500 // Emit section containing stack size metadata.
1501 emitStackSizeSection(*MF);
1502
1503 // Emit .su file containing function stack size information.
1504 emitStackUsage(*MF);
1505
1506 emitPatchableFunctionEntries();
1507
1508 if (isVerbose())
1509 OutStreamer->GetCommentOS() << "-- End function\n";
1510
1511 OutStreamer->AddBlankLine();
1512 }
1513
1514 /// Compute the number of Global Variables that uses a Constant.
getNumGlobalVariableUses(const Constant * C)1515 static unsigned getNumGlobalVariableUses(const Constant *C) {
1516 if (!C)
1517 return 0;
1518
1519 if (isa<GlobalVariable>(C))
1520 return 1;
1521
1522 unsigned NumUses = 0;
1523 for (auto *CU : C->users())
1524 NumUses += getNumGlobalVariableUses(dyn_cast<Constant>(CU));
1525
1526 return NumUses;
1527 }
1528
1529 /// Only consider global GOT equivalents if at least one user is a
1530 /// cstexpr inside an initializer of another global variables. Also, don't
1531 /// handle cstexpr inside instructions. During global variable emission,
1532 /// candidates are skipped and are emitted later in case at least one cstexpr
1533 /// isn't replaced by a PC relative GOT entry access.
isGOTEquivalentCandidate(const GlobalVariable * GV,unsigned & NumGOTEquivUsers)1534 static bool isGOTEquivalentCandidate(const GlobalVariable *GV,
1535 unsigned &NumGOTEquivUsers) {
1536 // Global GOT equivalents are unnamed private globals with a constant
1537 // pointer initializer to another global symbol. They must point to a
1538 // GlobalVariable or Function, i.e., as GlobalValue.
1539 if (!GV->hasGlobalUnnamedAddr() || !GV->hasInitializer() ||
1540 !GV->isConstant() || !GV->isDiscardableIfUnused() ||
1541 !isa<GlobalValue>(GV->getOperand(0)))
1542 return false;
1543
1544 // To be a got equivalent, at least one of its users need to be a constant
1545 // expression used by another global variable.
1546 for (auto *U : GV->users())
1547 NumGOTEquivUsers += getNumGlobalVariableUses(dyn_cast<Constant>(U));
1548
1549 return NumGOTEquivUsers > 0;
1550 }
1551
1552 /// Unnamed constant global variables solely contaning a pointer to
1553 /// another globals variable is equivalent to a GOT table entry; it contains the
1554 /// the address of another symbol. Optimize it and replace accesses to these
1555 /// "GOT equivalents" by using the GOT entry for the final global instead.
1556 /// Compute GOT equivalent candidates among all global variables to avoid
1557 /// emitting them if possible later on, after it use is replaced by a GOT entry
1558 /// access.
computeGlobalGOTEquivs(Module & M)1559 void AsmPrinter::computeGlobalGOTEquivs(Module &M) {
1560 if (!getObjFileLowering().supportIndirectSymViaGOTPCRel())
1561 return;
1562
1563 for (const auto &G : M.globals()) {
1564 unsigned NumGOTEquivUsers = 0;
1565 if (!isGOTEquivalentCandidate(&G, NumGOTEquivUsers))
1566 continue;
1567
1568 const MCSymbol *GOTEquivSym = getSymbol(&G);
1569 GlobalGOTEquivs[GOTEquivSym] = std::make_pair(&G, NumGOTEquivUsers);
1570 }
1571 }
1572
1573 /// Constant expressions using GOT equivalent globals may not be eligible
1574 /// for PC relative GOT entry conversion, in such cases we need to emit such
1575 /// globals we previously omitted in EmitGlobalVariable.
emitGlobalGOTEquivs()1576 void AsmPrinter::emitGlobalGOTEquivs() {
1577 if (!getObjFileLowering().supportIndirectSymViaGOTPCRel())
1578 return;
1579
1580 SmallVector<const GlobalVariable *, 8> FailedCandidates;
1581 for (auto &I : GlobalGOTEquivs) {
1582 const GlobalVariable *GV = I.second.first;
1583 unsigned Cnt = I.second.second;
1584 if (Cnt)
1585 FailedCandidates.push_back(GV);
1586 }
1587 GlobalGOTEquivs.clear();
1588
1589 for (auto *GV : FailedCandidates)
1590 emitGlobalVariable(GV);
1591 }
1592
emitGlobalIndirectSymbol(Module & M,const GlobalIndirectSymbol & GIS)1593 void AsmPrinter::emitGlobalIndirectSymbol(Module &M,
1594 const GlobalIndirectSymbol& GIS) {
1595 MCSymbol *Name = getSymbol(&GIS);
1596 bool IsFunction = GIS.getValueType()->isFunctionTy();
1597 // Treat bitcasts of functions as functions also. This is important at least
1598 // on WebAssembly where object and function addresses can't alias each other.
1599 if (!IsFunction)
1600 if (auto *CE = dyn_cast<ConstantExpr>(GIS.getIndirectSymbol()))
1601 if (CE->getOpcode() == Instruction::BitCast)
1602 IsFunction =
1603 CE->getOperand(0)->getType()->getPointerElementType()->isFunctionTy();
1604
1605 // AIX's assembly directive `.set` is not usable for aliasing purpose,
1606 // so AIX has to use the extra-label-at-definition strategy. At this
1607 // point, all the extra label is emitted, we just have to emit linkage for
1608 // those labels.
1609 if (TM.getTargetTriple().isOSBinFormatXCOFF()) {
1610 assert(!isa<GlobalIFunc>(GIS) && "IFunc is not supported on AIX.");
1611 assert(MAI->hasVisibilityOnlyWithLinkage() &&
1612 "Visibility should be handled with emitLinkage() on AIX.");
1613 emitLinkage(&GIS, Name);
1614 // If it's a function, also emit linkage for aliases of function entry
1615 // point.
1616 if (IsFunction)
1617 emitLinkage(&GIS,
1618 getObjFileLowering().getFunctionEntryPointSymbol(&GIS, TM));
1619 return;
1620 }
1621
1622 if (GIS.hasExternalLinkage() || !MAI->getWeakRefDirective())
1623 OutStreamer->emitSymbolAttribute(Name, MCSA_Global);
1624 else if (GIS.hasWeakLinkage() || GIS.hasLinkOnceLinkage())
1625 OutStreamer->emitSymbolAttribute(Name, MCSA_WeakReference);
1626 else
1627 assert(GIS.hasLocalLinkage() && "Invalid alias or ifunc linkage");
1628
1629 // Set the symbol type to function if the alias has a function type.
1630 // This affects codegen when the aliasee is not a function.
1631 if (IsFunction)
1632 OutStreamer->emitSymbolAttribute(Name, isa<GlobalIFunc>(GIS)
1633 ? MCSA_ELF_TypeIndFunction
1634 : MCSA_ELF_TypeFunction);
1635
1636 emitVisibility(Name, GIS.getVisibility());
1637
1638 const MCExpr *Expr = lowerConstant(GIS.getIndirectSymbol());
1639
1640 if (isa<GlobalAlias>(&GIS) && MAI->hasAltEntry() && isa<MCBinaryExpr>(Expr))
1641 OutStreamer->emitSymbolAttribute(Name, MCSA_AltEntry);
1642
1643 // Emit the directives as assignments aka .set:
1644 OutStreamer->emitAssignment(Name, Expr);
1645 MCSymbol *LocalAlias = getSymbolPreferLocal(GIS);
1646 if (LocalAlias != Name)
1647 OutStreamer->emitAssignment(LocalAlias, Expr);
1648
1649 if (auto *GA = dyn_cast<GlobalAlias>(&GIS)) {
1650 // If the aliasee does not correspond to a symbol in the output, i.e. the
1651 // alias is not of an object or the aliased object is private, then set the
1652 // size of the alias symbol from the type of the alias. We don't do this in
1653 // other situations as the alias and aliasee having differing types but same
1654 // size may be intentional.
1655 const GlobalObject *BaseObject = GA->getBaseObject();
1656 if (MAI->hasDotTypeDotSizeDirective() && GA->getValueType()->isSized() &&
1657 (!BaseObject || BaseObject->hasPrivateLinkage())) {
1658 const DataLayout &DL = M.getDataLayout();
1659 uint64_t Size = DL.getTypeAllocSize(GA->getValueType());
1660 OutStreamer->emitELFSize(Name, MCConstantExpr::create(Size, OutContext));
1661 }
1662 }
1663 }
1664
emitRemarksSection(remarks::RemarkStreamer & RS)1665 void AsmPrinter::emitRemarksSection(remarks::RemarkStreamer &RS) {
1666 if (!RS.needsSection())
1667 return;
1668
1669 remarks::RemarkSerializer &RemarkSerializer = RS.getSerializer();
1670
1671 Optional<SmallString<128>> Filename;
1672 if (Optional<StringRef> FilenameRef = RS.getFilename()) {
1673 Filename = *FilenameRef;
1674 sys::fs::make_absolute(*Filename);
1675 assert(!Filename->empty() && "The filename can't be empty.");
1676 }
1677
1678 std::string Buf;
1679 raw_string_ostream OS(Buf);
1680 std::unique_ptr<remarks::MetaSerializer> MetaSerializer =
1681 Filename ? RemarkSerializer.metaSerializer(OS, StringRef(*Filename))
1682 : RemarkSerializer.metaSerializer(OS);
1683 MetaSerializer->emit();
1684
1685 // Switch to the remarks section.
1686 MCSection *RemarksSection =
1687 OutContext.getObjectFileInfo()->getRemarksSection();
1688 OutStreamer->SwitchSection(RemarksSection);
1689
1690 OutStreamer->emitBinaryData(OS.str());
1691 }
1692
doFinalization(Module & M)1693 bool AsmPrinter::doFinalization(Module &M) {
1694 // Set the MachineFunction to nullptr so that we can catch attempted
1695 // accesses to MF specific features at the module level and so that
1696 // we can conditionalize accesses based on whether or not it is nullptr.
1697 MF = nullptr;
1698
1699 // Gather all GOT equivalent globals in the module. We really need two
1700 // passes over the globals: one to compute and another to avoid its emission
1701 // in EmitGlobalVariable, otherwise we would not be able to handle cases
1702 // where the got equivalent shows up before its use.
1703 computeGlobalGOTEquivs(M);
1704
1705 // Emit global variables.
1706 for (const auto &G : M.globals())
1707 emitGlobalVariable(&G);
1708
1709 // Emit remaining GOT equivalent globals.
1710 emitGlobalGOTEquivs();
1711
1712 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
1713
1714 // Emit linkage(XCOFF) and visibility info for declarations
1715 for (const Function &F : M) {
1716 if (!F.isDeclarationForLinker())
1717 continue;
1718
1719 MCSymbol *Name = getSymbol(&F);
1720 // Function getSymbol gives us the function descriptor symbol for XCOFF.
1721
1722 if (!TM.getTargetTriple().isOSBinFormatXCOFF()) {
1723 GlobalValue::VisibilityTypes V = F.getVisibility();
1724 if (V == GlobalValue::DefaultVisibility)
1725 continue;
1726
1727 emitVisibility(Name, V, false);
1728 continue;
1729 }
1730
1731 if (F.isIntrinsic())
1732 continue;
1733
1734 // Handle the XCOFF case.
1735 // Variable `Name` is the function descriptor symbol (see above). Get the
1736 // function entry point symbol.
1737 MCSymbol *FnEntryPointSym = TLOF.getFunctionEntryPointSymbol(&F, TM);
1738 // Emit linkage for the function entry point.
1739 emitLinkage(&F, FnEntryPointSym);
1740
1741 // Emit linkage for the function descriptor.
1742 emitLinkage(&F, Name);
1743 }
1744
1745 // Emit the remarks section contents.
1746 // FIXME: Figure out when is the safest time to emit this section. It should
1747 // not come after debug info.
1748 if (remarks::RemarkStreamer *RS = M.getContext().getMainRemarkStreamer())
1749 emitRemarksSection(*RS);
1750
1751 TLOF.emitModuleMetadata(*OutStreamer, M);
1752
1753 if (TM.getTargetTriple().isOSBinFormatELF()) {
1754 MachineModuleInfoELF &MMIELF = MMI->getObjFileInfo<MachineModuleInfoELF>();
1755
1756 // Output stubs for external and common global variables.
1757 MachineModuleInfoELF::SymbolListTy Stubs = MMIELF.GetGVStubList();
1758 if (!Stubs.empty()) {
1759 OutStreamer->SwitchSection(TLOF.getDataSection());
1760 const DataLayout &DL = M.getDataLayout();
1761
1762 emitAlignment(Align(DL.getPointerSize()));
1763 for (const auto &Stub : Stubs) {
1764 OutStreamer->emitLabel(Stub.first);
1765 OutStreamer->emitSymbolValue(Stub.second.getPointer(),
1766 DL.getPointerSize());
1767 }
1768 }
1769 }
1770
1771 if (TM.getTargetTriple().isOSBinFormatCOFF()) {
1772 MachineModuleInfoCOFF &MMICOFF =
1773 MMI->getObjFileInfo<MachineModuleInfoCOFF>();
1774
1775 // Output stubs for external and common global variables.
1776 MachineModuleInfoCOFF::SymbolListTy Stubs = MMICOFF.GetGVStubList();
1777 if (!Stubs.empty()) {
1778 const DataLayout &DL = M.getDataLayout();
1779
1780 for (const auto &Stub : Stubs) {
1781 SmallString<256> SectionName = StringRef(".rdata$");
1782 SectionName += Stub.first->getName();
1783 OutStreamer->SwitchSection(OutContext.getCOFFSection(
1784 SectionName,
1785 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
1786 COFF::IMAGE_SCN_LNK_COMDAT,
1787 SectionKind::getReadOnly(), Stub.first->getName(),
1788 COFF::IMAGE_COMDAT_SELECT_ANY));
1789 emitAlignment(Align(DL.getPointerSize()));
1790 OutStreamer->emitSymbolAttribute(Stub.first, MCSA_Global);
1791 OutStreamer->emitLabel(Stub.first);
1792 OutStreamer->emitSymbolValue(Stub.second.getPointer(),
1793 DL.getPointerSize());
1794 }
1795 }
1796 }
1797
1798 // Finalize debug and EH information.
1799 for (const HandlerInfo &HI : Handlers) {
1800 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1801 HI.TimerGroupDescription, TimePassesIsEnabled);
1802 HI.Handler->endModule();
1803 }
1804
1805 // This deletes all the ephemeral handlers that AsmPrinter added, while
1806 // keeping all the user-added handlers alive until the AsmPrinter is
1807 // destroyed.
1808 Handlers.erase(Handlers.begin() + NumUserHandlers, Handlers.end());
1809 DD = nullptr;
1810
1811 // If the target wants to know about weak references, print them all.
1812 if (MAI->getWeakRefDirective()) {
1813 // FIXME: This is not lazy, it would be nice to only print weak references
1814 // to stuff that is actually used. Note that doing so would require targets
1815 // to notice uses in operands (due to constant exprs etc). This should
1816 // happen with the MC stuff eventually.
1817
1818 // Print out module-level global objects here.
1819 for (const auto &GO : M.global_objects()) {
1820 if (!GO.hasExternalWeakLinkage())
1821 continue;
1822 OutStreamer->emitSymbolAttribute(getSymbol(&GO), MCSA_WeakReference);
1823 }
1824 }
1825
1826 // Print aliases in topological order, that is, for each alias a = b,
1827 // b must be printed before a.
1828 // This is because on some targets (e.g. PowerPC) linker expects aliases in
1829 // such an order to generate correct TOC information.
1830 SmallVector<const GlobalAlias *, 16> AliasStack;
1831 SmallPtrSet<const GlobalAlias *, 16> AliasVisited;
1832 for (const auto &Alias : M.aliases()) {
1833 for (const GlobalAlias *Cur = &Alias; Cur;
1834 Cur = dyn_cast<GlobalAlias>(Cur->getAliasee())) {
1835 if (!AliasVisited.insert(Cur).second)
1836 break;
1837 AliasStack.push_back(Cur);
1838 }
1839 for (const GlobalAlias *AncestorAlias : llvm::reverse(AliasStack))
1840 emitGlobalIndirectSymbol(M, *AncestorAlias);
1841 AliasStack.clear();
1842 }
1843 for (const auto &IFunc : M.ifuncs())
1844 emitGlobalIndirectSymbol(M, IFunc);
1845
1846 GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
1847 assert(MI && "AsmPrinter didn't require GCModuleInfo?");
1848 for (GCModuleInfo::iterator I = MI->end(), E = MI->begin(); I != E; )
1849 if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(**--I))
1850 MP->finishAssembly(M, *MI, *this);
1851
1852 // Emit llvm.ident metadata in an '.ident' directive.
1853 emitModuleIdents(M);
1854
1855 // Emit bytes for llvm.commandline metadata.
1856 emitModuleCommandLines(M);
1857
1858 // Emit __morestack address if needed for indirect calls.
1859 if (MMI->usesMorestackAddr()) {
1860 Align Alignment(1);
1861 MCSection *ReadOnlySection = getObjFileLowering().getSectionForConstant(
1862 getDataLayout(), SectionKind::getReadOnly(),
1863 /*C=*/nullptr, Alignment);
1864 OutStreamer->SwitchSection(ReadOnlySection);
1865
1866 MCSymbol *AddrSymbol =
1867 OutContext.getOrCreateSymbol(StringRef("__morestack_addr"));
1868 OutStreamer->emitLabel(AddrSymbol);
1869
1870 unsigned PtrSize = MAI->getCodePointerSize();
1871 OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("__morestack"),
1872 PtrSize);
1873 }
1874
1875 // Emit .note.GNU-split-stack and .note.GNU-no-split-stack sections if
1876 // split-stack is used.
1877 if (TM.getTargetTriple().isOSBinFormatELF() && MMI->hasSplitStack()) {
1878 OutStreamer->SwitchSection(
1879 OutContext.getELFSection(".note.GNU-split-stack", ELF::SHT_PROGBITS, 0));
1880 if (MMI->hasNosplitStack())
1881 OutStreamer->SwitchSection(
1882 OutContext.getELFSection(".note.GNU-no-split-stack", ELF::SHT_PROGBITS, 0));
1883 }
1884
1885 // If we don't have any trampolines, then we don't require stack memory
1886 // to be executable. Some targets have a directive to declare this.
1887 Function *InitTrampolineIntrinsic = M.getFunction("llvm.init.trampoline");
1888 if (!InitTrampolineIntrinsic || InitTrampolineIntrinsic->use_empty())
1889 if (MCSection *S = MAI->getNonexecutableStackSection(OutContext))
1890 OutStreamer->SwitchSection(S);
1891
1892 if (TM.Options.EmitAddrsig) {
1893 // Emit address-significance attributes for all globals.
1894 OutStreamer->emitAddrsig();
1895 for (const GlobalValue &GV : M.global_values()) {
1896 if (!GV.use_empty() && !GV.isTransitiveUsedByMetadataOnly() &&
1897 !GV.isThreadLocal() && !GV.hasDLLImportStorageClass() &&
1898 !GV.getName().startswith("llvm.") && !GV.hasAtLeastLocalUnnamedAddr())
1899 OutStreamer->emitAddrsigSym(getSymbol(&GV));
1900 }
1901 }
1902
1903 // Emit symbol partition specifications (ELF only).
1904 if (TM.getTargetTriple().isOSBinFormatELF()) {
1905 unsigned UniqueID = 0;
1906 for (const GlobalValue &GV : M.global_values()) {
1907 if (!GV.hasPartition() || GV.isDeclarationForLinker() ||
1908 GV.getVisibility() != GlobalValue::DefaultVisibility)
1909 continue;
1910
1911 OutStreamer->SwitchSection(
1912 OutContext.getELFSection(".llvm_sympart", ELF::SHT_LLVM_SYMPART, 0, 0,
1913 "", false, ++UniqueID, nullptr));
1914 OutStreamer->emitBytes(GV.getPartition());
1915 OutStreamer->emitZeros(1);
1916 OutStreamer->emitValue(
1917 MCSymbolRefExpr::create(getSymbol(&GV), OutContext),
1918 MAI->getCodePointerSize());
1919 }
1920 }
1921
1922 // Allow the target to emit any magic that it wants at the end of the file,
1923 // after everything else has gone out.
1924 emitEndOfAsmFile(M);
1925
1926 MMI = nullptr;
1927
1928 OutStreamer->Finish();
1929 OutStreamer->reset();
1930 OwnedMLI.reset();
1931 OwnedMDT.reset();
1932
1933 return false;
1934 }
1935
getMBBExceptionSym(const MachineBasicBlock & MBB)1936 MCSymbol *AsmPrinter::getMBBExceptionSym(const MachineBasicBlock &MBB) {
1937 auto Res = MBBSectionExceptionSyms.try_emplace(MBB.getSectionIDNum());
1938 if (Res.second)
1939 Res.first->second = createTempSymbol("exception");
1940 return Res.first->second;
1941 }
1942
SetupMachineFunction(MachineFunction & MF)1943 void AsmPrinter::SetupMachineFunction(MachineFunction &MF) {
1944 this->MF = &MF;
1945 const Function &F = MF.getFunction();
1946
1947 // Get the function symbol.
1948 if (!MAI->needsFunctionDescriptors()) {
1949 CurrentFnSym = getSymbol(&MF.getFunction());
1950 } else {
1951 assert(TM.getTargetTriple().isOSAIX() &&
1952 "Only AIX uses the function descriptor hooks.");
1953 // AIX is unique here in that the name of the symbol emitted for the
1954 // function body does not have the same name as the source function's
1955 // C-linkage name.
1956 assert(CurrentFnDescSym && "The function descriptor symbol needs to be"
1957 " initalized first.");
1958
1959 // Get the function entry point symbol.
1960 CurrentFnSym = getObjFileLowering().getFunctionEntryPointSymbol(&F, TM);
1961 }
1962
1963 CurrentFnSymForSize = CurrentFnSym;
1964 CurrentFnBegin = nullptr;
1965 CurrentSectionBeginSym = nullptr;
1966 MBBSectionRanges.clear();
1967 MBBSectionExceptionSyms.clear();
1968 bool NeedsLocalForSize = MAI->needsLocalForSize();
1969 if (F.hasFnAttribute("patchable-function-entry") ||
1970 F.hasFnAttribute("function-instrument") ||
1971 F.hasFnAttribute("xray-instruction-threshold") ||
1972 needFuncLabelsForEHOrDebugInfo(MF) || NeedsLocalForSize ||
1973 MF.getTarget().Options.EmitStackSizeSection || MF.hasBBLabels()) {
1974 CurrentFnBegin = createTempSymbol("func_begin");
1975 if (NeedsLocalForSize)
1976 CurrentFnSymForSize = CurrentFnBegin;
1977 }
1978
1979 ORE = &getAnalysis<MachineOptimizationRemarkEmitterPass>().getORE();
1980 }
1981
1982 namespace {
1983
1984 // Keep track the alignment, constpool entries per Section.
1985 struct SectionCPs {
1986 MCSection *S;
1987 Align Alignment;
1988 SmallVector<unsigned, 4> CPEs;
1989
SectionCPs__anon097d542e0211::SectionCPs1990 SectionCPs(MCSection *s, Align a) : S(s), Alignment(a) {}
1991 };
1992
1993 } // end anonymous namespace
1994
1995 /// EmitConstantPool - Print to the current output stream assembly
1996 /// representations of the constants in the constant pool MCP. This is
1997 /// used to print out constants which have been "spilled to memory" by
1998 /// the code generator.
emitConstantPool()1999 void AsmPrinter::emitConstantPool() {
2000 const MachineConstantPool *MCP = MF->getConstantPool();
2001 const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
2002 if (CP.empty()) return;
2003
2004 // Calculate sections for constant pool entries. We collect entries to go into
2005 // the same section together to reduce amount of section switch statements.
2006 SmallVector<SectionCPs, 4> CPSections;
2007 for (unsigned i = 0, e = CP.size(); i != e; ++i) {
2008 const MachineConstantPoolEntry &CPE = CP[i];
2009 Align Alignment = CPE.getAlign();
2010
2011 SectionKind Kind = CPE.getSectionKind(&getDataLayout());
2012
2013 const Constant *C = nullptr;
2014 if (!CPE.isMachineConstantPoolEntry())
2015 C = CPE.Val.ConstVal;
2016
2017 MCSection *S = getObjFileLowering().getSectionForConstant(
2018 getDataLayout(), Kind, C, Alignment);
2019
2020 // The number of sections are small, just do a linear search from the
2021 // last section to the first.
2022 bool Found = false;
2023 unsigned SecIdx = CPSections.size();
2024 while (SecIdx != 0) {
2025 if (CPSections[--SecIdx].S == S) {
2026 Found = true;
2027 break;
2028 }
2029 }
2030 if (!Found) {
2031 SecIdx = CPSections.size();
2032 CPSections.push_back(SectionCPs(S, Alignment));
2033 }
2034
2035 if (Alignment > CPSections[SecIdx].Alignment)
2036 CPSections[SecIdx].Alignment = Alignment;
2037 CPSections[SecIdx].CPEs.push_back(i);
2038 }
2039
2040 // Now print stuff into the calculated sections.
2041 const MCSection *CurSection = nullptr;
2042 unsigned Offset = 0;
2043 for (unsigned i = 0, e = CPSections.size(); i != e; ++i) {
2044 for (unsigned j = 0, ee = CPSections[i].CPEs.size(); j != ee; ++j) {
2045 unsigned CPI = CPSections[i].CPEs[j];
2046 MCSymbol *Sym = GetCPISymbol(CPI);
2047 if (!Sym->isUndefined())
2048 continue;
2049
2050 if (CurSection != CPSections[i].S) {
2051 OutStreamer->SwitchSection(CPSections[i].S);
2052 emitAlignment(Align(CPSections[i].Alignment));
2053 CurSection = CPSections[i].S;
2054 Offset = 0;
2055 }
2056
2057 MachineConstantPoolEntry CPE = CP[CPI];
2058
2059 // Emit inter-object padding for alignment.
2060 unsigned NewOffset = alignTo(Offset, CPE.getAlign());
2061 OutStreamer->emitZeros(NewOffset - Offset);
2062
2063 Offset = NewOffset + CPE.getSizeInBytes(getDataLayout());
2064
2065 OutStreamer->emitLabel(Sym);
2066 if (CPE.isMachineConstantPoolEntry())
2067 emitMachineConstantPoolValue(CPE.Val.MachineCPVal);
2068 else
2069 emitGlobalConstant(getDataLayout(), CPE.Val.ConstVal);
2070 }
2071 }
2072 }
2073
2074 // Print assembly representations of the jump tables used by the current
2075 // function.
emitJumpTableInfo()2076 void AsmPrinter::emitJumpTableInfo() {
2077 const DataLayout &DL = MF->getDataLayout();
2078 const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
2079 if (!MJTI) return;
2080 if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
2081 const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
2082 if (JT.empty()) return;
2083
2084 // Pick the directive to use to print the jump table entries, and switch to
2085 // the appropriate section.
2086 const Function &F = MF->getFunction();
2087 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
2088 bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
2089 MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32,
2090 F);
2091 if (JTInDiffSection) {
2092 // Drop it in the readonly section.
2093 MCSection *ReadOnlySection = TLOF.getSectionForJumpTable(F, TM);
2094 OutStreamer->SwitchSection(ReadOnlySection);
2095 }
2096
2097 emitAlignment(Align(MJTI->getEntryAlignment(DL)));
2098
2099 // Jump tables in code sections are marked with a data_region directive
2100 // where that's supported.
2101 if (!JTInDiffSection)
2102 OutStreamer->emitDataRegion(MCDR_DataRegionJT32);
2103
2104 for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
2105 const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
2106
2107 // If this jump table was deleted, ignore it.
2108 if (JTBBs.empty()) continue;
2109
2110 // For the EK_LabelDifference32 entry, if using .set avoids a relocation,
2111 /// emit a .set directive for each unique entry.
2112 if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
2113 MAI->doesSetDirectiveSuppressReloc()) {
2114 SmallPtrSet<const MachineBasicBlock*, 16> EmittedSets;
2115 const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
2116 const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF,JTI,OutContext);
2117 for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
2118 const MachineBasicBlock *MBB = JTBBs[ii];
2119 if (!EmittedSets.insert(MBB).second)
2120 continue;
2121
2122 // .set LJTSet, LBB32-base
2123 const MCExpr *LHS =
2124 MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
2125 OutStreamer->emitAssignment(GetJTSetSymbol(JTI, MBB->getNumber()),
2126 MCBinaryExpr::createSub(LHS, Base,
2127 OutContext));
2128 }
2129 }
2130
2131 // On some targets (e.g. Darwin) we want to emit two consecutive labels
2132 // before each jump table. The first label is never referenced, but tells
2133 // the assembler and linker the extents of the jump table object. The
2134 // second label is actually referenced by the code.
2135 if (JTInDiffSection && DL.hasLinkerPrivateGlobalPrefix())
2136 // FIXME: This doesn't have to have any specific name, just any randomly
2137 // named and numbered local label started with 'l' would work. Simplify
2138 // GetJTISymbol.
2139 OutStreamer->emitLabel(GetJTISymbol(JTI, true));
2140
2141 MCSymbol* JTISymbol = GetJTISymbol(JTI);
2142 OutStreamer->emitLabel(JTISymbol);
2143
2144 for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
2145 emitJumpTableEntry(MJTI, JTBBs[ii], JTI);
2146 }
2147 if (!JTInDiffSection)
2148 OutStreamer->emitDataRegion(MCDR_DataRegionEnd);
2149 }
2150
2151 /// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the
2152 /// current stream.
emitJumpTableEntry(const MachineJumpTableInfo * MJTI,const MachineBasicBlock * MBB,unsigned UID) const2153 void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
2154 const MachineBasicBlock *MBB,
2155 unsigned UID) const {
2156 assert(MBB && MBB->getNumber() >= 0 && "Invalid basic block");
2157 const MCExpr *Value = nullptr;
2158 switch (MJTI->getEntryKind()) {
2159 case MachineJumpTableInfo::EK_Inline:
2160 llvm_unreachable("Cannot emit EK_Inline jump table entry");
2161 case MachineJumpTableInfo::EK_Custom32:
2162 Value = MF->getSubtarget().getTargetLowering()->LowerCustomJumpTableEntry(
2163 MJTI, MBB, UID, OutContext);
2164 break;
2165 case MachineJumpTableInfo::EK_BlockAddress:
2166 // EK_BlockAddress - Each entry is a plain address of block, e.g.:
2167 // .word LBB123
2168 Value = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
2169 break;
2170 case MachineJumpTableInfo::EK_GPRel32BlockAddress: {
2171 // EK_GPRel32BlockAddress - Each entry is an address of block, encoded
2172 // with a relocation as gp-relative, e.g.:
2173 // .gprel32 LBB123
2174 MCSymbol *MBBSym = MBB->getSymbol();
2175 OutStreamer->emitGPRel32Value(MCSymbolRefExpr::create(MBBSym, OutContext));
2176 return;
2177 }
2178
2179 case MachineJumpTableInfo::EK_GPRel64BlockAddress: {
2180 // EK_GPRel64BlockAddress - Each entry is an address of block, encoded
2181 // with a relocation as gp-relative, e.g.:
2182 // .gpdword LBB123
2183 MCSymbol *MBBSym = MBB->getSymbol();
2184 OutStreamer->emitGPRel64Value(MCSymbolRefExpr::create(MBBSym, OutContext));
2185 return;
2186 }
2187
2188 case MachineJumpTableInfo::EK_LabelDifference32: {
2189 // Each entry is the address of the block minus the address of the jump
2190 // table. This is used for PIC jump tables where gprel32 is not supported.
2191 // e.g.:
2192 // .word LBB123 - LJTI1_2
2193 // If the .set directive avoids relocations, this is emitted as:
2194 // .set L4_5_set_123, LBB123 - LJTI1_2
2195 // .word L4_5_set_123
2196 if (MAI->doesSetDirectiveSuppressReloc()) {
2197 Value = MCSymbolRefExpr::create(GetJTSetSymbol(UID, MBB->getNumber()),
2198 OutContext);
2199 break;
2200 }
2201 Value = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
2202 const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
2203 const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF, UID, OutContext);
2204 Value = MCBinaryExpr::createSub(Value, Base, OutContext);
2205 break;
2206 }
2207 }
2208
2209 assert(Value && "Unknown entry kind!");
2210
2211 unsigned EntrySize = MJTI->getEntrySize(getDataLayout());
2212 OutStreamer->emitValue(Value, EntrySize);
2213 }
2214
2215 /// EmitSpecialLLVMGlobal - Check to see if the specified global is a
2216 /// special global used by LLVM. If so, emit it and return true, otherwise
2217 /// do nothing and return false.
emitSpecialLLVMGlobal(const GlobalVariable * GV)2218 bool AsmPrinter::emitSpecialLLVMGlobal(const GlobalVariable *GV) {
2219 if (GV->getName() == "llvm.used") {
2220 if (MAI->hasNoDeadStrip()) // No need to emit this at all.
2221 emitLLVMUsedList(cast<ConstantArray>(GV->getInitializer()));
2222 return true;
2223 }
2224
2225 // Ignore debug and non-emitted data. This handles llvm.compiler.used.
2226 if (GV->getSection() == "llvm.metadata" ||
2227 GV->hasAvailableExternallyLinkage())
2228 return true;
2229
2230 if (!GV->hasAppendingLinkage()) return false;
2231
2232 assert(GV->hasInitializer() && "Not a special LLVM global!");
2233
2234 if (GV->getName() == "llvm.global_ctors") {
2235 emitXXStructorList(GV->getParent()->getDataLayout(), GV->getInitializer(),
2236 /* isCtor */ true);
2237
2238 return true;
2239 }
2240
2241 if (GV->getName() == "llvm.global_dtors") {
2242 emitXXStructorList(GV->getParent()->getDataLayout(), GV->getInitializer(),
2243 /* isCtor */ false);
2244
2245 return true;
2246 }
2247
2248 report_fatal_error("unknown special variable");
2249 }
2250
2251 /// EmitLLVMUsedList - For targets that define a MAI::UsedDirective, mark each
2252 /// global in the specified llvm.used list.
emitLLVMUsedList(const ConstantArray * InitList)2253 void AsmPrinter::emitLLVMUsedList(const ConstantArray *InitList) {
2254 // Should be an array of 'i8*'.
2255 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
2256 const GlobalValue *GV =
2257 dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
2258 if (GV)
2259 OutStreamer->emitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip);
2260 }
2261 }
2262
preprocessXXStructorList(const DataLayout & DL,const Constant * List,SmallVector<Structor,8> & Structors)2263 void AsmPrinter::preprocessXXStructorList(const DataLayout &DL,
2264 const Constant *List,
2265 SmallVector<Structor, 8> &Structors) {
2266 // Should be an array of '{ i32, void ()*, i8* }' structs. The first value is
2267 // the init priority.
2268 if (!isa<ConstantArray>(List))
2269 return;
2270
2271 // Gather the structors in a form that's convenient for sorting by priority.
2272 for (Value *O : cast<ConstantArray>(List)->operands()) {
2273 auto *CS = cast<ConstantStruct>(O);
2274 if (CS->getOperand(1)->isNullValue())
2275 break; // Found a null terminator, skip the rest.
2276 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
2277 if (!Priority)
2278 continue; // Malformed.
2279 Structors.push_back(Structor());
2280 Structor &S = Structors.back();
2281 S.Priority = Priority->getLimitedValue(65535);
2282 S.Func = CS->getOperand(1);
2283 if (!CS->getOperand(2)->isNullValue()) {
2284 if (TM.getTargetTriple().isOSAIX())
2285 llvm::report_fatal_error(
2286 "associated data of XXStructor list is not yet supported on AIX");
2287 S.ComdatKey =
2288 dyn_cast<GlobalValue>(CS->getOperand(2)->stripPointerCasts());
2289 }
2290 }
2291
2292 // Emit the function pointers in the target-specific order
2293 llvm::stable_sort(Structors, [](const Structor &L, const Structor &R) {
2294 return L.Priority < R.Priority;
2295 });
2296 }
2297
2298 /// EmitXXStructorList - Emit the ctor or dtor list taking into account the init
2299 /// priority.
emitXXStructorList(const DataLayout & DL,const Constant * List,bool IsCtor)2300 void AsmPrinter::emitXXStructorList(const DataLayout &DL, const Constant *List,
2301 bool IsCtor) {
2302 SmallVector<Structor, 8> Structors;
2303 preprocessXXStructorList(DL, List, Structors);
2304 if (Structors.empty())
2305 return;
2306
2307 const Align Align = DL.getPointerPrefAlignment();
2308 for (Structor &S : Structors) {
2309 const TargetLoweringObjectFile &Obj = getObjFileLowering();
2310 const MCSymbol *KeySym = nullptr;
2311 if (GlobalValue *GV = S.ComdatKey) {
2312 if (GV->isDeclarationForLinker())
2313 // If the associated variable is not defined in this module
2314 // (it might be available_externally, or have been an
2315 // available_externally definition that was dropped by the
2316 // EliminateAvailableExternally pass), some other TU
2317 // will provide its dynamic initializer.
2318 continue;
2319
2320 KeySym = getSymbol(GV);
2321 }
2322
2323 MCSection *OutputSection =
2324 (IsCtor ? Obj.getStaticCtorSection(S.Priority, KeySym)
2325 : Obj.getStaticDtorSection(S.Priority, KeySym));
2326 OutStreamer->SwitchSection(OutputSection);
2327 if (OutStreamer->getCurrentSection() != OutStreamer->getPreviousSection())
2328 emitAlignment(Align);
2329 emitXXStructor(DL, S.Func);
2330 }
2331 }
2332
emitModuleIdents(Module & M)2333 void AsmPrinter::emitModuleIdents(Module &M) {
2334 if (!MAI->hasIdentDirective())
2335 return;
2336
2337 if (const NamedMDNode *NMD = M.getNamedMetadata("llvm.ident")) {
2338 for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
2339 const MDNode *N = NMD->getOperand(i);
2340 assert(N->getNumOperands() == 1 &&
2341 "llvm.ident metadata entry can have only one operand");
2342 const MDString *S = cast<MDString>(N->getOperand(0));
2343 OutStreamer->emitIdent(S->getString());
2344 }
2345 }
2346 }
2347
emitModuleCommandLines(Module & M)2348 void AsmPrinter::emitModuleCommandLines(Module &M) {
2349 MCSection *CommandLine = getObjFileLowering().getSectionForCommandLines();
2350 if (!CommandLine)
2351 return;
2352
2353 const NamedMDNode *NMD = M.getNamedMetadata("llvm.commandline");
2354 if (!NMD || !NMD->getNumOperands())
2355 return;
2356
2357 OutStreamer->PushSection();
2358 OutStreamer->SwitchSection(CommandLine);
2359 OutStreamer->emitZeros(1);
2360 for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
2361 const MDNode *N = NMD->getOperand(i);
2362 assert(N->getNumOperands() == 1 &&
2363 "llvm.commandline metadata entry can have only one operand");
2364 const MDString *S = cast<MDString>(N->getOperand(0));
2365 OutStreamer->emitBytes(S->getString());
2366 OutStreamer->emitZeros(1);
2367 }
2368 OutStreamer->PopSection();
2369 }
2370
2371 //===--------------------------------------------------------------------===//
2372 // Emission and print routines
2373 //
2374
2375 /// Emit a byte directive and value.
2376 ///
emitInt8(int Value) const2377 void AsmPrinter::emitInt8(int Value) const { OutStreamer->emitInt8(Value); }
2378
2379 /// Emit a short directive and value.
emitInt16(int Value) const2380 void AsmPrinter::emitInt16(int Value) const { OutStreamer->emitInt16(Value); }
2381
2382 /// Emit a long directive and value.
emitInt32(int Value) const2383 void AsmPrinter::emitInt32(int Value) const { OutStreamer->emitInt32(Value); }
2384
2385 /// Emit a long long directive and value.
emitInt64(uint64_t Value) const2386 void AsmPrinter::emitInt64(uint64_t Value) const {
2387 OutStreamer->emitInt64(Value);
2388 }
2389
2390 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
2391 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses
2392 /// .set if it avoids relocations.
emitLabelDifference(const MCSymbol * Hi,const MCSymbol * Lo,unsigned Size) const2393 void AsmPrinter::emitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
2394 unsigned Size) const {
2395 OutStreamer->emitAbsoluteSymbolDiff(Hi, Lo, Size);
2396 }
2397
2398 /// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
2399 /// where the size in bytes of the directive is specified by Size and Label
2400 /// specifies the label. This implicitly uses .set if it is available.
emitLabelPlusOffset(const MCSymbol * Label,uint64_t Offset,unsigned Size,bool IsSectionRelative) const2401 void AsmPrinter::emitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
2402 unsigned Size,
2403 bool IsSectionRelative) const {
2404 if (MAI->needsDwarfSectionOffsetDirective() && IsSectionRelative) {
2405 OutStreamer->EmitCOFFSecRel32(Label, Offset);
2406 if (Size > 4)
2407 OutStreamer->emitZeros(Size - 4);
2408 return;
2409 }
2410
2411 // Emit Label+Offset (or just Label if Offset is zero)
2412 const MCExpr *Expr = MCSymbolRefExpr::create(Label, OutContext);
2413 if (Offset)
2414 Expr = MCBinaryExpr::createAdd(
2415 Expr, MCConstantExpr::create(Offset, OutContext), OutContext);
2416
2417 OutStreamer->emitValue(Expr, Size);
2418 }
2419
2420 //===----------------------------------------------------------------------===//
2421
2422 // EmitAlignment - Emit an alignment directive to the specified power of
2423 // two boundary. If a global value is specified, and if that global has
2424 // an explicit alignment requested, it will override the alignment request
2425 // if required for correctness.
emitAlignment(Align Alignment,const GlobalObject * GV) const2426 void AsmPrinter::emitAlignment(Align Alignment, const GlobalObject *GV) const {
2427 if (GV)
2428 Alignment = getGVAlignment(GV, GV->getParent()->getDataLayout(), Alignment);
2429
2430 if (Alignment == Align(1))
2431 return; // 1-byte aligned: no need to emit alignment.
2432
2433 if (getCurrentSection()->getKind().isText())
2434 OutStreamer->emitCodeAlignment(Alignment.value());
2435 else
2436 OutStreamer->emitValueToAlignment(Alignment.value());
2437 }
2438
2439 //===----------------------------------------------------------------------===//
2440 // Constant emission.
2441 //===----------------------------------------------------------------------===//
2442
lowerConstant(const Constant * CV)2443 const MCExpr *AsmPrinter::lowerConstant(const Constant *CV) {
2444 MCContext &Ctx = OutContext;
2445
2446 if (CV->isNullValue() || isa<UndefValue>(CV))
2447 return MCConstantExpr::create(0, Ctx);
2448
2449 if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV))
2450 return MCConstantExpr::create(CI->getZExtValue(), Ctx);
2451
2452 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
2453 return MCSymbolRefExpr::create(getSymbol(GV), Ctx);
2454
2455 if (const BlockAddress *BA = dyn_cast<BlockAddress>(CV))
2456 return MCSymbolRefExpr::create(GetBlockAddressSymbol(BA), Ctx);
2457
2458 if (const auto *Equiv = dyn_cast<DSOLocalEquivalent>(CV))
2459 return getObjFileLowering().lowerDSOLocalEquivalent(Equiv, TM);
2460
2461 const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
2462 if (!CE) {
2463 llvm_unreachable("Unknown constant value to lower!");
2464 }
2465
2466 switch (CE->getOpcode()) {
2467 case Instruction::AddrSpaceCast: {
2468 const Constant *Op = CE->getOperand(0);
2469 unsigned DstAS = CE->getType()->getPointerAddressSpace();
2470 unsigned SrcAS = Op->getType()->getPointerAddressSpace();
2471 if (TM.isNoopAddrSpaceCast(SrcAS, DstAS))
2472 return lowerConstant(Op);
2473
2474 // Fallthrough to error.
2475 LLVM_FALLTHROUGH;
2476 }
2477 default: {
2478 // If the code isn't optimized, there may be outstanding folding
2479 // opportunities. Attempt to fold the expression using DataLayout as a
2480 // last resort before giving up.
2481 Constant *C = ConstantFoldConstant(CE, getDataLayout());
2482 if (C != CE)
2483 return lowerConstant(C);
2484
2485 // Otherwise report the problem to the user.
2486 std::string S;
2487 raw_string_ostream OS(S);
2488 OS << "Unsupported expression in static initializer: ";
2489 CE->printAsOperand(OS, /*PrintType=*/false,
2490 !MF ? nullptr : MF->getFunction().getParent());
2491 report_fatal_error(OS.str());
2492 }
2493 case Instruction::GetElementPtr: {
2494 // Generate a symbolic expression for the byte address
2495 APInt OffsetAI(getDataLayout().getPointerTypeSizeInBits(CE->getType()), 0);
2496 cast<GEPOperator>(CE)->accumulateConstantOffset(getDataLayout(), OffsetAI);
2497
2498 const MCExpr *Base = lowerConstant(CE->getOperand(0));
2499 if (!OffsetAI)
2500 return Base;
2501
2502 int64_t Offset = OffsetAI.getSExtValue();
2503 return MCBinaryExpr::createAdd(Base, MCConstantExpr::create(Offset, Ctx),
2504 Ctx);
2505 }
2506
2507 case Instruction::Trunc:
2508 // We emit the value and depend on the assembler to truncate the generated
2509 // expression properly. This is important for differences between
2510 // blockaddress labels. Since the two labels are in the same function, it
2511 // is reasonable to treat their delta as a 32-bit value.
2512 LLVM_FALLTHROUGH;
2513 case Instruction::BitCast:
2514 return lowerConstant(CE->getOperand(0));
2515
2516 case Instruction::IntToPtr: {
2517 const DataLayout &DL = getDataLayout();
2518
2519 // Handle casts to pointers by changing them into casts to the appropriate
2520 // integer type. This promotes constant folding and simplifies this code.
2521 Constant *Op = CE->getOperand(0);
2522 Op = ConstantExpr::getIntegerCast(Op, DL.getIntPtrType(CV->getType()),
2523 false/*ZExt*/);
2524 return lowerConstant(Op);
2525 }
2526
2527 case Instruction::PtrToInt: {
2528 const DataLayout &DL = getDataLayout();
2529
2530 // Support only foldable casts to/from pointers that can be eliminated by
2531 // changing the pointer to the appropriately sized integer type.
2532 Constant *Op = CE->getOperand(0);
2533 Type *Ty = CE->getType();
2534
2535 const MCExpr *OpExpr = lowerConstant(Op);
2536
2537 // We can emit the pointer value into this slot if the slot is an
2538 // integer slot equal to the size of the pointer.
2539 //
2540 // If the pointer is larger than the resultant integer, then
2541 // as with Trunc just depend on the assembler to truncate it.
2542 if (DL.getTypeAllocSize(Ty).getFixedSize() <=
2543 DL.getTypeAllocSize(Op->getType()).getFixedSize())
2544 return OpExpr;
2545
2546 // Otherwise the pointer is smaller than the resultant integer, mask off
2547 // the high bits so we are sure to get a proper truncation if the input is
2548 // a constant expr.
2549 unsigned InBits = DL.getTypeAllocSizeInBits(Op->getType());
2550 const MCExpr *MaskExpr = MCConstantExpr::create(~0ULL >> (64-InBits), Ctx);
2551 return MCBinaryExpr::createAnd(OpExpr, MaskExpr, Ctx);
2552 }
2553
2554 case Instruction::Sub: {
2555 GlobalValue *LHSGV;
2556 APInt LHSOffset;
2557 DSOLocalEquivalent *DSOEquiv;
2558 if (IsConstantOffsetFromGlobal(CE->getOperand(0), LHSGV, LHSOffset,
2559 getDataLayout(), &DSOEquiv)) {
2560 GlobalValue *RHSGV;
2561 APInt RHSOffset;
2562 if (IsConstantOffsetFromGlobal(CE->getOperand(1), RHSGV, RHSOffset,
2563 getDataLayout())) {
2564 const MCExpr *RelocExpr =
2565 getObjFileLowering().lowerRelativeReference(LHSGV, RHSGV, TM);
2566 if (!RelocExpr) {
2567 const MCExpr *LHSExpr =
2568 MCSymbolRefExpr::create(getSymbol(LHSGV), Ctx);
2569 if (DSOEquiv &&
2570 getObjFileLowering().supportDSOLocalEquivalentLowering())
2571 LHSExpr =
2572 getObjFileLowering().lowerDSOLocalEquivalent(DSOEquiv, TM);
2573 RelocExpr = MCBinaryExpr::createSub(
2574 LHSExpr, MCSymbolRefExpr::create(getSymbol(RHSGV), Ctx), Ctx);
2575 }
2576 int64_t Addend = (LHSOffset - RHSOffset).getSExtValue();
2577 if (Addend != 0)
2578 RelocExpr = MCBinaryExpr::createAdd(
2579 RelocExpr, MCConstantExpr::create(Addend, Ctx), Ctx);
2580 return RelocExpr;
2581 }
2582 }
2583 }
2584 // else fallthrough
2585 LLVM_FALLTHROUGH;
2586
2587 // The MC library also has a right-shift operator, but it isn't consistently
2588 // signed or unsigned between different targets.
2589 case Instruction::Add:
2590 case Instruction::Mul:
2591 case Instruction::SDiv:
2592 case Instruction::SRem:
2593 case Instruction::Shl:
2594 case Instruction::And:
2595 case Instruction::Or:
2596 case Instruction::Xor: {
2597 const MCExpr *LHS = lowerConstant(CE->getOperand(0));
2598 const MCExpr *RHS = lowerConstant(CE->getOperand(1));
2599 switch (CE->getOpcode()) {
2600 default: llvm_unreachable("Unknown binary operator constant cast expr");
2601 case Instruction::Add: return MCBinaryExpr::createAdd(LHS, RHS, Ctx);
2602 case Instruction::Sub: return MCBinaryExpr::createSub(LHS, RHS, Ctx);
2603 case Instruction::Mul: return MCBinaryExpr::createMul(LHS, RHS, Ctx);
2604 case Instruction::SDiv: return MCBinaryExpr::createDiv(LHS, RHS, Ctx);
2605 case Instruction::SRem: return MCBinaryExpr::createMod(LHS, RHS, Ctx);
2606 case Instruction::Shl: return MCBinaryExpr::createShl(LHS, RHS, Ctx);
2607 case Instruction::And: return MCBinaryExpr::createAnd(LHS, RHS, Ctx);
2608 case Instruction::Or: return MCBinaryExpr::createOr (LHS, RHS, Ctx);
2609 case Instruction::Xor: return MCBinaryExpr::createXor(LHS, RHS, Ctx);
2610 }
2611 }
2612 }
2613 }
2614
2615 static void emitGlobalConstantImpl(const DataLayout &DL, const Constant *C,
2616 AsmPrinter &AP,
2617 const Constant *BaseCV = nullptr,
2618 uint64_t Offset = 0);
2619
2620 static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP);
2621 static void emitGlobalConstantFP(APFloat APF, Type *ET, AsmPrinter &AP);
2622
2623 /// isRepeatedByteSequence - Determine whether the given value is
2624 /// composed of a repeated sequence of identical bytes and return the
2625 /// byte value. If it is not a repeated sequence, return -1.
isRepeatedByteSequence(const ConstantDataSequential * V)2626 static int isRepeatedByteSequence(const ConstantDataSequential *V) {
2627 StringRef Data = V->getRawDataValues();
2628 assert(!Data.empty() && "Empty aggregates should be CAZ node");
2629 char C = Data[0];
2630 for (unsigned i = 1, e = Data.size(); i != e; ++i)
2631 if (Data[i] != C) return -1;
2632 return static_cast<uint8_t>(C); // Ensure 255 is not returned as -1.
2633 }
2634
2635 /// isRepeatedByteSequence - Determine whether the given value is
2636 /// composed of a repeated sequence of identical bytes and return the
2637 /// byte value. If it is not a repeated sequence, return -1.
isRepeatedByteSequence(const Value * V,const DataLayout & DL)2638 static int isRepeatedByteSequence(const Value *V, const DataLayout &DL) {
2639 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
2640 uint64_t Size = DL.getTypeAllocSizeInBits(V->getType());
2641 assert(Size % 8 == 0);
2642
2643 // Extend the element to take zero padding into account.
2644 APInt Value = CI->getValue().zextOrSelf(Size);
2645 if (!Value.isSplat(8))
2646 return -1;
2647
2648 return Value.zextOrTrunc(8).getZExtValue();
2649 }
2650 if (const ConstantArray *CA = dyn_cast<ConstantArray>(V)) {
2651 // Make sure all array elements are sequences of the same repeated
2652 // byte.
2653 assert(CA->getNumOperands() != 0 && "Should be a CAZ");
2654 Constant *Op0 = CA->getOperand(0);
2655 int Byte = isRepeatedByteSequence(Op0, DL);
2656 if (Byte == -1)
2657 return -1;
2658
2659 // All array elements must be equal.
2660 for (unsigned i = 1, e = CA->getNumOperands(); i != e; ++i)
2661 if (CA->getOperand(i) != Op0)
2662 return -1;
2663 return Byte;
2664 }
2665
2666 if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(V))
2667 return isRepeatedByteSequence(CDS);
2668
2669 return -1;
2670 }
2671
emitGlobalConstantDataSequential(const DataLayout & DL,const ConstantDataSequential * CDS,AsmPrinter & AP)2672 static void emitGlobalConstantDataSequential(const DataLayout &DL,
2673 const ConstantDataSequential *CDS,
2674 AsmPrinter &AP) {
2675 // See if we can aggregate this into a .fill, if so, emit it as such.
2676 int Value = isRepeatedByteSequence(CDS, DL);
2677 if (Value != -1) {
2678 uint64_t Bytes = DL.getTypeAllocSize(CDS->getType());
2679 // Don't emit a 1-byte object as a .fill.
2680 if (Bytes > 1)
2681 return AP.OutStreamer->emitFill(Bytes, Value);
2682 }
2683
2684 // If this can be emitted with .ascii/.asciz, emit it as such.
2685 if (CDS->isString())
2686 return AP.OutStreamer->emitBytes(CDS->getAsString());
2687
2688 // Otherwise, emit the values in successive locations.
2689 unsigned ElementByteSize = CDS->getElementByteSize();
2690 if (isa<IntegerType>(CDS->getElementType())) {
2691 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
2692 if (AP.isVerbose())
2693 AP.OutStreamer->GetCommentOS() << format("0x%" PRIx64 "\n",
2694 CDS->getElementAsInteger(i));
2695 AP.OutStreamer->emitIntValue(CDS->getElementAsInteger(i),
2696 ElementByteSize);
2697 }
2698 } else {
2699 Type *ET = CDS->getElementType();
2700 for (unsigned I = 0, E = CDS->getNumElements(); I != E; ++I)
2701 emitGlobalConstantFP(CDS->getElementAsAPFloat(I), ET, AP);
2702 }
2703
2704 unsigned Size = DL.getTypeAllocSize(CDS->getType());
2705 unsigned EmittedSize =
2706 DL.getTypeAllocSize(CDS->getElementType()) * CDS->getNumElements();
2707 assert(EmittedSize <= Size && "Size cannot be less than EmittedSize!");
2708 if (unsigned Padding = Size - EmittedSize)
2709 AP.OutStreamer->emitZeros(Padding);
2710 }
2711
emitGlobalConstantArray(const DataLayout & DL,const ConstantArray * CA,AsmPrinter & AP,const Constant * BaseCV,uint64_t Offset)2712 static void emitGlobalConstantArray(const DataLayout &DL,
2713 const ConstantArray *CA, AsmPrinter &AP,
2714 const Constant *BaseCV, uint64_t Offset) {
2715 // See if we can aggregate some values. Make sure it can be
2716 // represented as a series of bytes of the constant value.
2717 int Value = isRepeatedByteSequence(CA, DL);
2718
2719 if (Value != -1) {
2720 uint64_t Bytes = DL.getTypeAllocSize(CA->getType());
2721 AP.OutStreamer->emitFill(Bytes, Value);
2722 }
2723 else {
2724 for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
2725 emitGlobalConstantImpl(DL, CA->getOperand(i), AP, BaseCV, Offset);
2726 Offset += DL.getTypeAllocSize(CA->getOperand(i)->getType());
2727 }
2728 }
2729 }
2730
emitGlobalConstantVector(const DataLayout & DL,const ConstantVector * CV,AsmPrinter & AP)2731 static void emitGlobalConstantVector(const DataLayout &DL,
2732 const ConstantVector *CV, AsmPrinter &AP) {
2733 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
2734 emitGlobalConstantImpl(DL, CV->getOperand(i), AP);
2735
2736 unsigned Size = DL.getTypeAllocSize(CV->getType());
2737 unsigned EmittedSize = DL.getTypeAllocSize(CV->getType()->getElementType()) *
2738 CV->getType()->getNumElements();
2739 if (unsigned Padding = Size - EmittedSize)
2740 AP.OutStreamer->emitZeros(Padding);
2741 }
2742
emitGlobalConstantStruct(const DataLayout & DL,const ConstantStruct * CS,AsmPrinter & AP,const Constant * BaseCV,uint64_t Offset)2743 static void emitGlobalConstantStruct(const DataLayout &DL,
2744 const ConstantStruct *CS, AsmPrinter &AP,
2745 const Constant *BaseCV, uint64_t Offset) {
2746 // Print the fields in successive locations. Pad to align if needed!
2747 unsigned Size = DL.getTypeAllocSize(CS->getType());
2748 const StructLayout *Layout = DL.getStructLayout(CS->getType());
2749 uint64_t SizeSoFar = 0;
2750 for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
2751 const Constant *Field = CS->getOperand(i);
2752
2753 // Print the actual field value.
2754 emitGlobalConstantImpl(DL, Field, AP, BaseCV, Offset + SizeSoFar);
2755
2756 // Check if padding is needed and insert one or more 0s.
2757 uint64_t FieldSize = DL.getTypeAllocSize(Field->getType());
2758 uint64_t PadSize = ((i == e-1 ? Size : Layout->getElementOffset(i+1))
2759 - Layout->getElementOffset(i)) - FieldSize;
2760 SizeSoFar += FieldSize + PadSize;
2761
2762 // Insert padding - this may include padding to increase the size of the
2763 // current field up to the ABI size (if the struct is not packed) as well
2764 // as padding to ensure that the next field starts at the right offset.
2765 AP.OutStreamer->emitZeros(PadSize);
2766 }
2767 assert(SizeSoFar == Layout->getSizeInBytes() &&
2768 "Layout of constant struct may be incorrect!");
2769 }
2770
emitGlobalConstantFP(APFloat APF,Type * ET,AsmPrinter & AP)2771 static void emitGlobalConstantFP(APFloat APF, Type *ET, AsmPrinter &AP) {
2772 assert(ET && "Unknown float type");
2773 APInt API = APF.bitcastToAPInt();
2774
2775 // First print a comment with what we think the original floating-point value
2776 // should have been.
2777 if (AP.isVerbose()) {
2778 SmallString<8> StrVal;
2779 APF.toString(StrVal);
2780 ET->print(AP.OutStreamer->GetCommentOS());
2781 AP.OutStreamer->GetCommentOS() << ' ' << StrVal << '\n';
2782 }
2783
2784 // Now iterate through the APInt chunks, emitting them in endian-correct
2785 // order, possibly with a smaller chunk at beginning/end (e.g. for x87 80-bit
2786 // floats).
2787 unsigned NumBytes = API.getBitWidth() / 8;
2788 unsigned TrailingBytes = NumBytes % sizeof(uint64_t);
2789 const uint64_t *p = API.getRawData();
2790
2791 // PPC's long double has odd notions of endianness compared to how LLVM
2792 // handles it: p[0] goes first for *big* endian on PPC.
2793 if (AP.getDataLayout().isBigEndian() && !ET->isPPC_FP128Ty()) {
2794 int Chunk = API.getNumWords() - 1;
2795
2796 if (TrailingBytes)
2797 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk--], TrailingBytes);
2798
2799 for (; Chunk >= 0; --Chunk)
2800 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], sizeof(uint64_t));
2801 } else {
2802 unsigned Chunk;
2803 for (Chunk = 0; Chunk < NumBytes / sizeof(uint64_t); ++Chunk)
2804 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], sizeof(uint64_t));
2805
2806 if (TrailingBytes)
2807 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], TrailingBytes);
2808 }
2809
2810 // Emit the tail padding for the long double.
2811 const DataLayout &DL = AP.getDataLayout();
2812 AP.OutStreamer->emitZeros(DL.getTypeAllocSize(ET) - DL.getTypeStoreSize(ET));
2813 }
2814
emitGlobalConstantFP(const ConstantFP * CFP,AsmPrinter & AP)2815 static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP) {
2816 emitGlobalConstantFP(CFP->getValueAPF(), CFP->getType(), AP);
2817 }
2818
emitGlobalConstantLargeInt(const ConstantInt * CI,AsmPrinter & AP)2819 static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP) {
2820 const DataLayout &DL = AP.getDataLayout();
2821 unsigned BitWidth = CI->getBitWidth();
2822
2823 // Copy the value as we may massage the layout for constants whose bit width
2824 // is not a multiple of 64-bits.
2825 APInt Realigned(CI->getValue());
2826 uint64_t ExtraBits = 0;
2827 unsigned ExtraBitsSize = BitWidth & 63;
2828
2829 if (ExtraBitsSize) {
2830 // The bit width of the data is not a multiple of 64-bits.
2831 // The extra bits are expected to be at the end of the chunk of the memory.
2832 // Little endian:
2833 // * Nothing to be done, just record the extra bits to emit.
2834 // Big endian:
2835 // * Record the extra bits to emit.
2836 // * Realign the raw data to emit the chunks of 64-bits.
2837 if (DL.isBigEndian()) {
2838 // Basically the structure of the raw data is a chunk of 64-bits cells:
2839 // 0 1 BitWidth / 64
2840 // [chunk1][chunk2] ... [chunkN].
2841 // The most significant chunk is chunkN and it should be emitted first.
2842 // However, due to the alignment issue chunkN contains useless bits.
2843 // Realign the chunks so that they contain only useful information:
2844 // ExtraBits 0 1 (BitWidth / 64) - 1
2845 // chu[nk1 chu][nk2 chu] ... [nkN-1 chunkN]
2846 ExtraBitsSize = alignTo(ExtraBitsSize, 8);
2847 ExtraBits = Realigned.getRawData()[0] &
2848 (((uint64_t)-1) >> (64 - ExtraBitsSize));
2849 Realigned.lshrInPlace(ExtraBitsSize);
2850 } else
2851 ExtraBits = Realigned.getRawData()[BitWidth / 64];
2852 }
2853
2854 // We don't expect assemblers to support integer data directives
2855 // for more than 64 bits, so we emit the data in at most 64-bit
2856 // quantities at a time.
2857 const uint64_t *RawData = Realigned.getRawData();
2858 for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
2859 uint64_t Val = DL.isBigEndian() ? RawData[e - i - 1] : RawData[i];
2860 AP.OutStreamer->emitIntValue(Val, 8);
2861 }
2862
2863 if (ExtraBitsSize) {
2864 // Emit the extra bits after the 64-bits chunks.
2865
2866 // Emit a directive that fills the expected size.
2867 uint64_t Size = AP.getDataLayout().getTypeStoreSize(CI->getType());
2868 Size -= (BitWidth / 64) * 8;
2869 assert(Size && Size * 8 >= ExtraBitsSize &&
2870 (ExtraBits & (((uint64_t)-1) >> (64 - ExtraBitsSize)))
2871 == ExtraBits && "Directive too small for extra bits.");
2872 AP.OutStreamer->emitIntValue(ExtraBits, Size);
2873 }
2874 }
2875
2876 /// Transform a not absolute MCExpr containing a reference to a GOT
2877 /// equivalent global, by a target specific GOT pc relative access to the
2878 /// final symbol.
handleIndirectSymViaGOTPCRel(AsmPrinter & AP,const MCExpr ** ME,const Constant * BaseCst,uint64_t Offset)2879 static void handleIndirectSymViaGOTPCRel(AsmPrinter &AP, const MCExpr **ME,
2880 const Constant *BaseCst,
2881 uint64_t Offset) {
2882 // The global @foo below illustrates a global that uses a got equivalent.
2883 //
2884 // @bar = global i32 42
2885 // @gotequiv = private unnamed_addr constant i32* @bar
2886 // @foo = i32 trunc (i64 sub (i64 ptrtoint (i32** @gotequiv to i64),
2887 // i64 ptrtoint (i32* @foo to i64))
2888 // to i32)
2889 //
2890 // The cstexpr in @foo is converted into the MCExpr `ME`, where we actually
2891 // check whether @foo is suitable to use a GOTPCREL. `ME` is usually in the
2892 // form:
2893 //
2894 // foo = cstexpr, where
2895 // cstexpr := <gotequiv> - "." + <cst>
2896 // cstexpr := <gotequiv> - (<foo> - <offset from @foo base>) + <cst>
2897 //
2898 // After canonicalization by evaluateAsRelocatable `ME` turns into:
2899 //
2900 // cstexpr := <gotequiv> - <foo> + gotpcrelcst, where
2901 // gotpcrelcst := <offset from @foo base> + <cst>
2902 MCValue MV;
2903 if (!(*ME)->evaluateAsRelocatable(MV, nullptr, nullptr) || MV.isAbsolute())
2904 return;
2905 const MCSymbolRefExpr *SymA = MV.getSymA();
2906 if (!SymA)
2907 return;
2908
2909 // Check that GOT equivalent symbol is cached.
2910 const MCSymbol *GOTEquivSym = &SymA->getSymbol();
2911 if (!AP.GlobalGOTEquivs.count(GOTEquivSym))
2912 return;
2913
2914 const GlobalValue *BaseGV = dyn_cast_or_null<GlobalValue>(BaseCst);
2915 if (!BaseGV)
2916 return;
2917
2918 // Check for a valid base symbol
2919 const MCSymbol *BaseSym = AP.getSymbol(BaseGV);
2920 const MCSymbolRefExpr *SymB = MV.getSymB();
2921
2922 if (!SymB || BaseSym != &SymB->getSymbol())
2923 return;
2924
2925 // Make sure to match:
2926 //
2927 // gotpcrelcst := <offset from @foo base> + <cst>
2928 //
2929 // If gotpcrelcst is positive it means that we can safely fold the pc rel
2930 // displacement into the GOTPCREL. We can also can have an extra offset <cst>
2931 // if the target knows how to encode it.
2932 int64_t GOTPCRelCst = Offset + MV.getConstant();
2933 if (GOTPCRelCst < 0)
2934 return;
2935 if (!AP.getObjFileLowering().supportGOTPCRelWithOffset() && GOTPCRelCst != 0)
2936 return;
2937
2938 // Emit the GOT PC relative to replace the got equivalent global, i.e.:
2939 //
2940 // bar:
2941 // .long 42
2942 // gotequiv:
2943 // .quad bar
2944 // foo:
2945 // .long gotequiv - "." + <cst>
2946 //
2947 // is replaced by the target specific equivalent to:
2948 //
2949 // bar:
2950 // .long 42
2951 // foo:
2952 // .long bar@GOTPCREL+<gotpcrelcst>
2953 AsmPrinter::GOTEquivUsePair Result = AP.GlobalGOTEquivs[GOTEquivSym];
2954 const GlobalVariable *GV = Result.first;
2955 int NumUses = (int)Result.second;
2956 const GlobalValue *FinalGV = dyn_cast<GlobalValue>(GV->getOperand(0));
2957 const MCSymbol *FinalSym = AP.getSymbol(FinalGV);
2958 *ME = AP.getObjFileLowering().getIndirectSymViaGOTPCRel(
2959 FinalGV, FinalSym, MV, Offset, AP.MMI, *AP.OutStreamer);
2960
2961 // Update GOT equivalent usage information
2962 --NumUses;
2963 if (NumUses >= 0)
2964 AP.GlobalGOTEquivs[GOTEquivSym] = std::make_pair(GV, NumUses);
2965 }
2966
emitGlobalConstantImpl(const DataLayout & DL,const Constant * CV,AsmPrinter & AP,const Constant * BaseCV,uint64_t Offset)2967 static void emitGlobalConstantImpl(const DataLayout &DL, const Constant *CV,
2968 AsmPrinter &AP, const Constant *BaseCV,
2969 uint64_t Offset) {
2970 uint64_t Size = DL.getTypeAllocSize(CV->getType());
2971
2972 // Globals with sub-elements such as combinations of arrays and structs
2973 // are handled recursively by emitGlobalConstantImpl. Keep track of the
2974 // constant symbol base and the current position with BaseCV and Offset.
2975 if (!BaseCV && CV->hasOneUse())
2976 BaseCV = dyn_cast<Constant>(CV->user_back());
2977
2978 if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
2979 return AP.OutStreamer->emitZeros(Size);
2980
2981 if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
2982 const uint64_t StoreSize = DL.getTypeStoreSize(CV->getType());
2983
2984 if (StoreSize <= 8) {
2985 if (AP.isVerbose())
2986 AP.OutStreamer->GetCommentOS() << format("0x%" PRIx64 "\n",
2987 CI->getZExtValue());
2988 AP.OutStreamer->emitIntValue(CI->getZExtValue(), StoreSize);
2989 } else {
2990 emitGlobalConstantLargeInt(CI, AP);
2991 }
2992
2993 // Emit tail padding if needed
2994 if (Size != StoreSize)
2995 AP.OutStreamer->emitZeros(Size - StoreSize);
2996
2997 return;
2998 }
2999
3000 if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV))
3001 return emitGlobalConstantFP(CFP, AP);
3002
3003 if (isa<ConstantPointerNull>(CV)) {
3004 AP.OutStreamer->emitIntValue(0, Size);
3005 return;
3006 }
3007
3008 if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(CV))
3009 return emitGlobalConstantDataSequential(DL, CDS, AP);
3010
3011 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV))
3012 return emitGlobalConstantArray(DL, CVA, AP, BaseCV, Offset);
3013
3014 if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
3015 return emitGlobalConstantStruct(DL, CVS, AP, BaseCV, Offset);
3016
3017 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
3018 // Look through bitcasts, which might not be able to be MCExpr'ized (e.g. of
3019 // vectors).
3020 if (CE->getOpcode() == Instruction::BitCast)
3021 return emitGlobalConstantImpl(DL, CE->getOperand(0), AP);
3022
3023 if (Size > 8) {
3024 // If the constant expression's size is greater than 64-bits, then we have
3025 // to emit the value in chunks. Try to constant fold the value and emit it
3026 // that way.
3027 Constant *New = ConstantFoldConstant(CE, DL);
3028 if (New != CE)
3029 return emitGlobalConstantImpl(DL, New, AP);
3030 }
3031 }
3032
3033 if (const ConstantVector *V = dyn_cast<ConstantVector>(CV))
3034 return emitGlobalConstantVector(DL, V, AP);
3035
3036 // Otherwise, it must be a ConstantExpr. Lower it to an MCExpr, then emit it
3037 // thread the streamer with EmitValue.
3038 const MCExpr *ME = AP.lowerConstant(CV);
3039
3040 // Since lowerConstant already folded and got rid of all IR pointer and
3041 // integer casts, detect GOT equivalent accesses by looking into the MCExpr
3042 // directly.
3043 if (AP.getObjFileLowering().supportIndirectSymViaGOTPCRel())
3044 handleIndirectSymViaGOTPCRel(AP, &ME, BaseCV, Offset);
3045
3046 AP.OutStreamer->emitValue(ME, Size);
3047 }
3048
3049 /// EmitGlobalConstant - Print a general LLVM constant to the .s file.
emitGlobalConstant(const DataLayout & DL,const Constant * CV)3050 void AsmPrinter::emitGlobalConstant(const DataLayout &DL, const Constant *CV) {
3051 uint64_t Size = DL.getTypeAllocSize(CV->getType());
3052 if (Size)
3053 emitGlobalConstantImpl(DL, CV, *this);
3054 else if (MAI->hasSubsectionsViaSymbols()) {
3055 // If the global has zero size, emit a single byte so that two labels don't
3056 // look like they are at the same location.
3057 OutStreamer->emitIntValue(0, 1);
3058 }
3059 }
3060
emitMachineConstantPoolValue(MachineConstantPoolValue * MCPV)3061 void AsmPrinter::emitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) {
3062 // Target doesn't support this yet!
3063 llvm_unreachable("Target does not support EmitMachineConstantPoolValue");
3064 }
3065
printOffset(int64_t Offset,raw_ostream & OS) const3066 void AsmPrinter::printOffset(int64_t Offset, raw_ostream &OS) const {
3067 if (Offset > 0)
3068 OS << '+' << Offset;
3069 else if (Offset < 0)
3070 OS << Offset;
3071 }
3072
emitNops(unsigned N)3073 void AsmPrinter::emitNops(unsigned N) {
3074 MCInst Nop = MF->getSubtarget().getInstrInfo()->getNop();
3075 for (; N; --N)
3076 EmitToStreamer(*OutStreamer, Nop);
3077 }
3078
3079 //===----------------------------------------------------------------------===//
3080 // Symbol Lowering Routines.
3081 //===----------------------------------------------------------------------===//
3082
createTempSymbol(const Twine & Name) const3083 MCSymbol *AsmPrinter::createTempSymbol(const Twine &Name) const {
3084 return OutContext.createTempSymbol(Name, true);
3085 }
3086
GetBlockAddressSymbol(const BlockAddress * BA) const3087 MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BlockAddress *BA) const {
3088 return MMI->getAddrLabelSymbol(BA->getBasicBlock());
3089 }
3090
GetBlockAddressSymbol(const BasicBlock * BB) const3091 MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BasicBlock *BB) const {
3092 return MMI->getAddrLabelSymbol(BB);
3093 }
3094
3095 /// GetCPISymbol - Return the symbol for the specified constant pool entry.
GetCPISymbol(unsigned CPID) const3096 MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
3097 if (getSubtargetInfo().getTargetTriple().isWindowsMSVCEnvironment()) {
3098 const MachineConstantPoolEntry &CPE =
3099 MF->getConstantPool()->getConstants()[CPID];
3100 if (!CPE.isMachineConstantPoolEntry()) {
3101 const DataLayout &DL = MF->getDataLayout();
3102 SectionKind Kind = CPE.getSectionKind(&DL);
3103 const Constant *C = CPE.Val.ConstVal;
3104 Align Alignment = CPE.Alignment;
3105 if (const MCSectionCOFF *S = dyn_cast<MCSectionCOFF>(
3106 getObjFileLowering().getSectionForConstant(DL, Kind, C,
3107 Alignment))) {
3108 if (MCSymbol *Sym = S->getCOMDATSymbol()) {
3109 if (Sym->isUndefined())
3110 OutStreamer->emitSymbolAttribute(Sym, MCSA_Global);
3111 return Sym;
3112 }
3113 }
3114 }
3115 }
3116
3117 const DataLayout &DL = getDataLayout();
3118 return OutContext.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
3119 "CPI" + Twine(getFunctionNumber()) + "_" +
3120 Twine(CPID));
3121 }
3122
3123 /// GetJTISymbol - Return the symbol for the specified jump table entry.
GetJTISymbol(unsigned JTID,bool isLinkerPrivate) const3124 MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool isLinkerPrivate) const {
3125 return MF->getJTISymbol(JTID, OutContext, isLinkerPrivate);
3126 }
3127
3128 /// GetJTSetSymbol - Return the symbol for the specified jump table .set
3129 /// FIXME: privatize to AsmPrinter.
GetJTSetSymbol(unsigned UID,unsigned MBBID) const3130 MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
3131 const DataLayout &DL = getDataLayout();
3132 return OutContext.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
3133 Twine(getFunctionNumber()) + "_" +
3134 Twine(UID) + "_set_" + Twine(MBBID));
3135 }
3136
getSymbolWithGlobalValueBase(const GlobalValue * GV,StringRef Suffix) const3137 MCSymbol *AsmPrinter::getSymbolWithGlobalValueBase(const GlobalValue *GV,
3138 StringRef Suffix) const {
3139 return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, TM);
3140 }
3141
3142 /// Return the MCSymbol for the specified ExternalSymbol.
GetExternalSymbolSymbol(StringRef Sym) const3143 MCSymbol *AsmPrinter::GetExternalSymbolSymbol(StringRef Sym) const {
3144 SmallString<60> NameStr;
3145 Mangler::getNameWithPrefix(NameStr, Sym, getDataLayout());
3146 return OutContext.getOrCreateSymbol(NameStr);
3147 }
3148
3149 /// PrintParentLoopComment - Print comments about parent loops of this one.
PrintParentLoopComment(raw_ostream & OS,const MachineLoop * Loop,unsigned FunctionNumber)3150 static void PrintParentLoopComment(raw_ostream &OS, const MachineLoop *Loop,
3151 unsigned FunctionNumber) {
3152 if (!Loop) return;
3153 PrintParentLoopComment(OS, Loop->getParentLoop(), FunctionNumber);
3154 OS.indent(Loop->getLoopDepth()*2)
3155 << "Parent Loop BB" << FunctionNumber << "_"
3156 << Loop->getHeader()->getNumber()
3157 << " Depth=" << Loop->getLoopDepth() << '\n';
3158 }
3159
3160 /// PrintChildLoopComment - Print comments about child loops within
3161 /// the loop for this basic block, with nesting.
PrintChildLoopComment(raw_ostream & OS,const MachineLoop * Loop,unsigned FunctionNumber)3162 static void PrintChildLoopComment(raw_ostream &OS, const MachineLoop *Loop,
3163 unsigned FunctionNumber) {
3164 // Add child loop information
3165 for (const MachineLoop *CL : *Loop) {
3166 OS.indent(CL->getLoopDepth()*2)
3167 << "Child Loop BB" << FunctionNumber << "_"
3168 << CL->getHeader()->getNumber() << " Depth " << CL->getLoopDepth()
3169 << '\n';
3170 PrintChildLoopComment(OS, CL, FunctionNumber);
3171 }
3172 }
3173
3174 /// emitBasicBlockLoopComments - Pretty-print comments for basic blocks.
emitBasicBlockLoopComments(const MachineBasicBlock & MBB,const MachineLoopInfo * LI,const AsmPrinter & AP)3175 static void emitBasicBlockLoopComments(const MachineBasicBlock &MBB,
3176 const MachineLoopInfo *LI,
3177 const AsmPrinter &AP) {
3178 // Add loop depth information
3179 const MachineLoop *Loop = LI->getLoopFor(&MBB);
3180 if (!Loop) return;
3181
3182 MachineBasicBlock *Header = Loop->getHeader();
3183 assert(Header && "No header for loop");
3184
3185 // If this block is not a loop header, just print out what is the loop header
3186 // and return.
3187 if (Header != &MBB) {
3188 AP.OutStreamer->AddComment(" in Loop: Header=BB" +
3189 Twine(AP.getFunctionNumber())+"_" +
3190 Twine(Loop->getHeader()->getNumber())+
3191 " Depth="+Twine(Loop->getLoopDepth()));
3192 return;
3193 }
3194
3195 // Otherwise, it is a loop header. Print out information about child and
3196 // parent loops.
3197 raw_ostream &OS = AP.OutStreamer->GetCommentOS();
3198
3199 PrintParentLoopComment(OS, Loop->getParentLoop(), AP.getFunctionNumber());
3200
3201 OS << "=>";
3202 OS.indent(Loop->getLoopDepth()*2-2);
3203
3204 OS << "This ";
3205 if (Loop->isInnermost())
3206 OS << "Inner ";
3207 OS << "Loop Header: Depth=" + Twine(Loop->getLoopDepth()) << '\n';
3208
3209 PrintChildLoopComment(OS, Loop, AP.getFunctionNumber());
3210 }
3211
3212 /// emitBasicBlockStart - This method prints the label for the specified
3213 /// MachineBasicBlock, an alignment (if present) and a comment describing
3214 /// it if appropriate.
emitBasicBlockStart(const MachineBasicBlock & MBB)3215 void AsmPrinter::emitBasicBlockStart(const MachineBasicBlock &MBB) {
3216 // End the previous funclet and start a new one.
3217 if (MBB.isEHFuncletEntry()) {
3218 for (const HandlerInfo &HI : Handlers) {
3219 HI.Handler->endFunclet();
3220 HI.Handler->beginFunclet(MBB);
3221 }
3222 }
3223
3224 // Emit an alignment directive for this block, if needed.
3225 const Align Alignment = MBB.getAlignment();
3226 if (Alignment != Align(1))
3227 emitAlignment(Alignment);
3228
3229 // Switch to a new section if this basic block must begin a section. The
3230 // entry block is always placed in the function section and is handled
3231 // separately.
3232 if (MBB.isBeginSection() && !MBB.isEntryBlock()) {
3233 OutStreamer->SwitchSection(
3234 getObjFileLowering().getSectionForMachineBasicBlock(MF->getFunction(),
3235 MBB, TM));
3236 CurrentSectionBeginSym = MBB.getSymbol();
3237 }
3238
3239 // If the block has its address taken, emit any labels that were used to
3240 // reference the block. It is possible that there is more than one label
3241 // here, because multiple LLVM BB's may have been RAUW'd to this block after
3242 // the references were generated.
3243 if (MBB.hasAddressTaken()) {
3244 const BasicBlock *BB = MBB.getBasicBlock();
3245 if (isVerbose())
3246 OutStreamer->AddComment("Block address taken");
3247
3248 // MBBs can have their address taken as part of CodeGen without having
3249 // their corresponding BB's address taken in IR
3250 if (BB->hasAddressTaken())
3251 for (MCSymbol *Sym : MMI->getAddrLabelSymbolToEmit(BB))
3252 OutStreamer->emitLabel(Sym);
3253 }
3254
3255 // Print some verbose block comments.
3256 if (isVerbose()) {
3257 if (const BasicBlock *BB = MBB.getBasicBlock()) {
3258 if (BB->hasName()) {
3259 BB->printAsOperand(OutStreamer->GetCommentOS(),
3260 /*PrintType=*/false, BB->getModule());
3261 OutStreamer->GetCommentOS() << '\n';
3262 }
3263 }
3264
3265 assert(MLI != nullptr && "MachineLoopInfo should has been computed");
3266 emitBasicBlockLoopComments(MBB, MLI, *this);
3267 }
3268
3269 // Print the main label for the block.
3270 if (shouldEmitLabelForBasicBlock(MBB)) {
3271 if (isVerbose() && MBB.hasLabelMustBeEmitted())
3272 OutStreamer->AddComment("Label of block must be emitted");
3273 OutStreamer->emitLabel(MBB.getSymbol());
3274 } else {
3275 if (isVerbose()) {
3276 // NOTE: Want this comment at start of line, don't emit with AddComment.
3277 OutStreamer->emitRawComment(" %bb." + Twine(MBB.getNumber()) + ":",
3278 false);
3279 }
3280 }
3281
3282 if (MBB.isEHCatchretTarget() &&
3283 MAI->getExceptionHandlingType() == ExceptionHandling::WinEH) {
3284 OutStreamer->emitLabel(MBB.getEHCatchretSymbol());
3285 }
3286
3287 // With BB sections, each basic block must handle CFI information on its own
3288 // if it begins a section (Entry block is handled separately by
3289 // AsmPrinterHandler::beginFunction).
3290 if (MBB.isBeginSection() && !MBB.isEntryBlock())
3291 for (const HandlerInfo &HI : Handlers)
3292 HI.Handler->beginBasicBlock(MBB);
3293 }
3294
emitBasicBlockEnd(const MachineBasicBlock & MBB)3295 void AsmPrinter::emitBasicBlockEnd(const MachineBasicBlock &MBB) {
3296 // Check if CFI information needs to be updated for this MBB with basic block
3297 // sections.
3298 if (MBB.isEndSection())
3299 for (const HandlerInfo &HI : Handlers)
3300 HI.Handler->endBasicBlock(MBB);
3301 }
3302
emitVisibility(MCSymbol * Sym,unsigned Visibility,bool IsDefinition) const3303 void AsmPrinter::emitVisibility(MCSymbol *Sym, unsigned Visibility,
3304 bool IsDefinition) const {
3305 MCSymbolAttr Attr = MCSA_Invalid;
3306
3307 switch (Visibility) {
3308 default: break;
3309 case GlobalValue::HiddenVisibility:
3310 if (IsDefinition)
3311 Attr = MAI->getHiddenVisibilityAttr();
3312 else
3313 Attr = MAI->getHiddenDeclarationVisibilityAttr();
3314 break;
3315 case GlobalValue::ProtectedVisibility:
3316 Attr = MAI->getProtectedVisibilityAttr();
3317 break;
3318 }
3319
3320 if (Attr != MCSA_Invalid)
3321 OutStreamer->emitSymbolAttribute(Sym, Attr);
3322 }
3323
shouldEmitLabelForBasicBlock(const MachineBasicBlock & MBB) const3324 bool AsmPrinter::shouldEmitLabelForBasicBlock(
3325 const MachineBasicBlock &MBB) const {
3326 // With `-fbasic-block-sections=`, a label is needed for every non-entry block
3327 // in the labels mode (option `=labels`) and every section beginning in the
3328 // sections mode (`=all` and `=list=`).
3329 if ((MF->hasBBLabels() || MBB.isBeginSection()) && !MBB.isEntryBlock())
3330 return true;
3331 // A label is needed for any block with at least one predecessor (when that
3332 // predecessor is not the fallthrough predecessor, or if it is an EH funclet
3333 // entry, or if a label is forced).
3334 return !MBB.pred_empty() &&
3335 (!isBlockOnlyReachableByFallthrough(&MBB) || MBB.isEHFuncletEntry() ||
3336 MBB.hasLabelMustBeEmitted());
3337 }
3338
3339 /// isBlockOnlyReachableByFallthough - Return true if the basic block has
3340 /// exactly one predecessor and the control transfer mechanism between
3341 /// the predecessor and this block is a fall-through.
3342 bool AsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock * MBB) const3343 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
3344 // If this is a landing pad, it isn't a fall through. If it has no preds,
3345 // then nothing falls through to it.
3346 if (MBB->isEHPad() || MBB->pred_empty())
3347 return false;
3348
3349 // If there isn't exactly one predecessor, it can't be a fall through.
3350 if (MBB->pred_size() > 1)
3351 return false;
3352
3353 // The predecessor has to be immediately before this block.
3354 MachineBasicBlock *Pred = *MBB->pred_begin();
3355 if (!Pred->isLayoutSuccessor(MBB))
3356 return false;
3357
3358 // If the block is completely empty, then it definitely does fall through.
3359 if (Pred->empty())
3360 return true;
3361
3362 // Check the terminators in the previous blocks
3363 for (const auto &MI : Pred->terminators()) {
3364 // If it is not a simple branch, we are in a table somewhere.
3365 if (!MI.isBranch() || MI.isIndirectBranch())
3366 return false;
3367
3368 // If we are the operands of one of the branches, this is not a fall
3369 // through. Note that targets with delay slots will usually bundle
3370 // terminators with the delay slot instruction.
3371 for (ConstMIBundleOperands OP(MI); OP.isValid(); ++OP) {
3372 if (OP->isJTI())
3373 return false;
3374 if (OP->isMBB() && OP->getMBB() == MBB)
3375 return false;
3376 }
3377 }
3378
3379 return true;
3380 }
3381
GetOrCreateGCPrinter(GCStrategy & S)3382 GCMetadataPrinter *AsmPrinter::GetOrCreateGCPrinter(GCStrategy &S) {
3383 if (!S.usesMetadata())
3384 return nullptr;
3385
3386 gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
3387 gcp_map_type::iterator GCPI = GCMap.find(&S);
3388 if (GCPI != GCMap.end())
3389 return GCPI->second.get();
3390
3391 auto Name = S.getName();
3392
3393 for (const GCMetadataPrinterRegistry::entry &GCMetaPrinter :
3394 GCMetadataPrinterRegistry::entries())
3395 if (Name == GCMetaPrinter.getName()) {
3396 std::unique_ptr<GCMetadataPrinter> GMP = GCMetaPrinter.instantiate();
3397 GMP->S = &S;
3398 auto IterBool = GCMap.insert(std::make_pair(&S, std::move(GMP)));
3399 return IterBool.first->second.get();
3400 }
3401
3402 report_fatal_error("no GCMetadataPrinter registered for GC: " + Twine(Name));
3403 }
3404
emitStackMaps(StackMaps & SM)3405 void AsmPrinter::emitStackMaps(StackMaps &SM) {
3406 GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
3407 assert(MI && "AsmPrinter didn't require GCModuleInfo?");
3408 bool NeedsDefault = false;
3409 if (MI->begin() == MI->end())
3410 // No GC strategy, use the default format.
3411 NeedsDefault = true;
3412 else
3413 for (auto &I : *MI) {
3414 if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(*I))
3415 if (MP->emitStackMaps(SM, *this))
3416 continue;
3417 // The strategy doesn't have printer or doesn't emit custom stack maps.
3418 // Use the default format.
3419 NeedsDefault = true;
3420 }
3421
3422 if (NeedsDefault)
3423 SM.serializeToStackMapSection();
3424 }
3425
3426 /// Pin vtable to this file.
3427 AsmPrinterHandler::~AsmPrinterHandler() = default;
3428
markFunctionEnd()3429 void AsmPrinterHandler::markFunctionEnd() {}
3430
3431 // In the binary's "xray_instr_map" section, an array of these function entries
3432 // describes each instrumentation point. When XRay patches your code, the index
3433 // into this table will be given to your handler as a patch point identifier.
emit(int Bytes,MCStreamer * Out) const3434 void AsmPrinter::XRayFunctionEntry::emit(int Bytes, MCStreamer *Out) const {
3435 auto Kind8 = static_cast<uint8_t>(Kind);
3436 Out->emitBinaryData(StringRef(reinterpret_cast<const char *>(&Kind8), 1));
3437 Out->emitBinaryData(
3438 StringRef(reinterpret_cast<const char *>(&AlwaysInstrument), 1));
3439 Out->emitBinaryData(StringRef(reinterpret_cast<const char *>(&Version), 1));
3440 auto Padding = (4 * Bytes) - ((2 * Bytes) + 3);
3441 assert(Padding >= 0 && "Instrumentation map entry > 4 * Word Size");
3442 Out->emitZeros(Padding);
3443 }
3444
emitXRayTable()3445 void AsmPrinter::emitXRayTable() {
3446 if (Sleds.empty())
3447 return;
3448
3449 auto PrevSection = OutStreamer->getCurrentSectionOnly();
3450 const Function &F = MF->getFunction();
3451 MCSection *InstMap = nullptr;
3452 MCSection *FnSledIndex = nullptr;
3453 const Triple &TT = TM.getTargetTriple();
3454 // Use PC-relative addresses on all targets.
3455 if (TT.isOSBinFormatELF()) {
3456 auto LinkedToSym = cast<MCSymbolELF>(CurrentFnSym);
3457 auto Flags = ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER;
3458 StringRef GroupName;
3459 if (F.hasComdat()) {
3460 Flags |= ELF::SHF_GROUP;
3461 GroupName = F.getComdat()->getName();
3462 }
3463 InstMap = OutContext.getELFSection("xray_instr_map", ELF::SHT_PROGBITS,
3464 Flags, 0, GroupName, F.hasComdat(),
3465 MCSection::NonUniqueID, LinkedToSym);
3466
3467 if (!TM.Options.XRayOmitFunctionIndex)
3468 FnSledIndex = OutContext.getELFSection(
3469 "xray_fn_idx", ELF::SHT_PROGBITS, Flags | ELF::SHF_WRITE, 0,
3470 GroupName, F.hasComdat(), MCSection::NonUniqueID, LinkedToSym);
3471 } else if (MF->getSubtarget().getTargetTriple().isOSBinFormatMachO()) {
3472 InstMap = OutContext.getMachOSection("__DATA", "xray_instr_map", 0,
3473 SectionKind::getReadOnlyWithRel());
3474 if (!TM.Options.XRayOmitFunctionIndex)
3475 FnSledIndex = OutContext.getMachOSection(
3476 "__DATA", "xray_fn_idx", 0, SectionKind::getReadOnlyWithRel());
3477 } else {
3478 llvm_unreachable("Unsupported target");
3479 }
3480
3481 auto WordSizeBytes = MAI->getCodePointerSize();
3482
3483 // Now we switch to the instrumentation map section. Because this is done
3484 // per-function, we are able to create an index entry that will represent the
3485 // range of sleds associated with a function.
3486 auto &Ctx = OutContext;
3487 MCSymbol *SledsStart = OutContext.createTempSymbol("xray_sleds_start", true);
3488 OutStreamer->SwitchSection(InstMap);
3489 OutStreamer->emitLabel(SledsStart);
3490 for (const auto &Sled : Sleds) {
3491 MCSymbol *Dot = Ctx.createTempSymbol();
3492 OutStreamer->emitLabel(Dot);
3493 OutStreamer->emitValueImpl(
3494 MCBinaryExpr::createSub(MCSymbolRefExpr::create(Sled.Sled, Ctx),
3495 MCSymbolRefExpr::create(Dot, Ctx), Ctx),
3496 WordSizeBytes);
3497 OutStreamer->emitValueImpl(
3498 MCBinaryExpr::createSub(
3499 MCSymbolRefExpr::create(CurrentFnBegin, Ctx),
3500 MCBinaryExpr::createAdd(MCSymbolRefExpr::create(Dot, Ctx),
3501 MCConstantExpr::create(WordSizeBytes, Ctx),
3502 Ctx),
3503 Ctx),
3504 WordSizeBytes);
3505 Sled.emit(WordSizeBytes, OutStreamer.get());
3506 }
3507 MCSymbol *SledsEnd = OutContext.createTempSymbol("xray_sleds_end", true);
3508 OutStreamer->emitLabel(SledsEnd);
3509
3510 // We then emit a single entry in the index per function. We use the symbols
3511 // that bound the instrumentation map as the range for a specific function.
3512 // Each entry here will be 2 * word size aligned, as we're writing down two
3513 // pointers. This should work for both 32-bit and 64-bit platforms.
3514 if (FnSledIndex) {
3515 OutStreamer->SwitchSection(FnSledIndex);
3516 OutStreamer->emitCodeAlignment(2 * WordSizeBytes);
3517 OutStreamer->emitSymbolValue(SledsStart, WordSizeBytes, false);
3518 OutStreamer->emitSymbolValue(SledsEnd, WordSizeBytes, false);
3519 OutStreamer->SwitchSection(PrevSection);
3520 }
3521 Sleds.clear();
3522 }
3523
recordSled(MCSymbol * Sled,const MachineInstr & MI,SledKind Kind,uint8_t Version)3524 void AsmPrinter::recordSled(MCSymbol *Sled, const MachineInstr &MI,
3525 SledKind Kind, uint8_t Version) {
3526 const Function &F = MI.getMF()->getFunction();
3527 auto Attr = F.getFnAttribute("function-instrument");
3528 bool LogArgs = F.hasFnAttribute("xray-log-args");
3529 bool AlwaysInstrument =
3530 Attr.isStringAttribute() && Attr.getValueAsString() == "xray-always";
3531 if (Kind == SledKind::FUNCTION_ENTER && LogArgs)
3532 Kind = SledKind::LOG_ARGS_ENTER;
3533 Sleds.emplace_back(XRayFunctionEntry{Sled, CurrentFnSym, Kind,
3534 AlwaysInstrument, &F, Version});
3535 }
3536
emitPatchableFunctionEntries()3537 void AsmPrinter::emitPatchableFunctionEntries() {
3538 const Function &F = MF->getFunction();
3539 unsigned PatchableFunctionPrefix = 0, PatchableFunctionEntry = 0;
3540 (void)F.getFnAttribute("patchable-function-prefix")
3541 .getValueAsString()
3542 .getAsInteger(10, PatchableFunctionPrefix);
3543 (void)F.getFnAttribute("patchable-function-entry")
3544 .getValueAsString()
3545 .getAsInteger(10, PatchableFunctionEntry);
3546 if (!PatchableFunctionPrefix && !PatchableFunctionEntry)
3547 return;
3548 const unsigned PointerSize = getPointerSize();
3549 if (TM.getTargetTriple().isOSBinFormatELF()) {
3550 auto Flags = ELF::SHF_WRITE | ELF::SHF_ALLOC;
3551 const MCSymbolELF *LinkedToSym = nullptr;
3552 StringRef GroupName;
3553
3554 // GNU as < 2.35 did not support section flag 'o'. GNU ld < 2.36 did not
3555 // support mixed SHF_LINK_ORDER and non-SHF_LINK_ORDER sections.
3556 if (MAI->useIntegratedAssembler() || MAI->binutilsIsAtLeast(2, 36)) {
3557 Flags |= ELF::SHF_LINK_ORDER;
3558 if (F.hasComdat()) {
3559 Flags |= ELF::SHF_GROUP;
3560 GroupName = F.getComdat()->getName();
3561 }
3562 LinkedToSym = cast<MCSymbolELF>(CurrentFnSym);
3563 }
3564 OutStreamer->SwitchSection(OutContext.getELFSection(
3565 "__patchable_function_entries", ELF::SHT_PROGBITS, Flags, 0, GroupName,
3566 F.hasComdat(), MCSection::NonUniqueID, LinkedToSym));
3567 emitAlignment(Align(PointerSize));
3568 OutStreamer->emitSymbolValue(CurrentPatchableFunctionEntrySym, PointerSize);
3569 }
3570 }
3571
getDwarfVersion() const3572 uint16_t AsmPrinter::getDwarfVersion() const {
3573 return OutStreamer->getContext().getDwarfVersion();
3574 }
3575
setDwarfVersion(uint16_t Version)3576 void AsmPrinter::setDwarfVersion(uint16_t Version) {
3577 OutStreamer->getContext().setDwarfVersion(Version);
3578 }
3579
isDwarf64() const3580 bool AsmPrinter::isDwarf64() const {
3581 return OutStreamer->getContext().getDwarfFormat() == dwarf::DWARF64;
3582 }
3583
getDwarfOffsetByteSize() const3584 unsigned int AsmPrinter::getDwarfOffsetByteSize() const {
3585 return dwarf::getDwarfOffsetByteSize(
3586 OutStreamer->getContext().getDwarfFormat());
3587 }
3588
getUnitLengthFieldByteSize() const3589 unsigned int AsmPrinter::getUnitLengthFieldByteSize() const {
3590 return dwarf::getUnitLengthFieldByteSize(
3591 OutStreamer->getContext().getDwarfFormat());
3592 }
3593