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 "WasmException.h"
18 #include "WinCFGuard.h"
19 #include "WinException.h"
20 #include "llvm/ADT/APFloat.h"
21 #include "llvm/ADT/APInt.h"
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/ADT/STLExtras.h"
24 #include "llvm/ADT/SmallPtrSet.h"
25 #include "llvm/ADT/SmallString.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/Statistic.h"
28 #include "llvm/ADT/StringRef.h"
29 #include "llvm/ADT/Triple.h"
30 #include "llvm/ADT/Twine.h"
31 #include "llvm/Analysis/ConstantFolding.h"
32 #include "llvm/Analysis/EHPersonalities.h"
33 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
34 #include "llvm/BinaryFormat/COFF.h"
35 #include "llvm/BinaryFormat/Dwarf.h"
36 #include "llvm/BinaryFormat/ELF.h"
37 #include "llvm/CodeGen/GCMetadata.h"
38 #include "llvm/CodeGen/GCMetadataPrinter.h"
39 #include "llvm/CodeGen/GCStrategy.h"
40 #include "llvm/CodeGen/MachineBasicBlock.h"
41 #include "llvm/CodeGen/MachineConstantPool.h"
42 #include "llvm/CodeGen/MachineDominators.h"
43 #include "llvm/CodeGen/MachineFrameInfo.h"
44 #include "llvm/CodeGen/MachineFunction.h"
45 #include "llvm/CodeGen/MachineFunctionPass.h"
46 #include "llvm/CodeGen/MachineInstr.h"
47 #include "llvm/CodeGen/MachineInstrBundle.h"
48 #include "llvm/CodeGen/MachineJumpTableInfo.h"
49 #include "llvm/CodeGen/MachineLoopInfo.h"
50 #include "llvm/CodeGen/MachineMemOperand.h"
51 #include "llvm/CodeGen/MachineModuleInfo.h"
52 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
53 #include "llvm/CodeGen/MachineOperand.h"
54 #include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
55 #include "llvm/CodeGen/StackMaps.h"
56 #include "llvm/CodeGen/TargetFrameLowering.h"
57 #include "llvm/CodeGen/TargetInstrInfo.h"
58 #include "llvm/CodeGen/TargetLowering.h"
59 #include "llvm/CodeGen/TargetOpcodes.h"
60 #include "llvm/CodeGen/TargetRegisterInfo.h"
61 #include "llvm/IR/BasicBlock.h"
62 #include "llvm/IR/Comdat.h"
63 #include "llvm/IR/Constant.h"
64 #include "llvm/IR/Constants.h"
65 #include "llvm/IR/DataLayout.h"
66 #include "llvm/IR/DebugInfoMetadata.h"
67 #include "llvm/IR/DerivedTypes.h"
68 #include "llvm/IR/Function.h"
69 #include "llvm/IR/GlobalAlias.h"
70 #include "llvm/IR/GlobalIFunc.h"
71 #include "llvm/IR/GlobalIndirectSymbol.h"
72 #include "llvm/IR/GlobalObject.h"
73 #include "llvm/IR/GlobalValue.h"
74 #include "llvm/IR/GlobalVariable.h"
75 #include "llvm/IR/Instruction.h"
76 #include "llvm/IR/Mangler.h"
77 #include "llvm/IR/Metadata.h"
78 #include "llvm/IR/Module.h"
79 #include "llvm/IR/Operator.h"
80 #include "llvm/IR/Type.h"
81 #include "llvm/IR/Value.h"
82 #include "llvm/MC/MCAsmInfo.h"
83 #include "llvm/MC/MCContext.h"
84 #include "llvm/MC/MCDirectives.h"
85 #include "llvm/MC/MCDwarf.h"
86 #include "llvm/MC/MCExpr.h"
87 #include "llvm/MC/MCInst.h"
88 #include "llvm/MC/MCSection.h"
89 #include "llvm/MC/MCSectionCOFF.h"
90 #include "llvm/MC/MCSectionELF.h"
91 #include "llvm/MC/MCSectionMachO.h"
92 #include "llvm/MC/MCSectionXCOFF.h"
93 #include "llvm/MC/MCStreamer.h"
94 #include "llvm/MC/MCSubtargetInfo.h"
95 #include "llvm/MC/MCSymbol.h"
96 #include "llvm/MC/MCSymbolELF.h"
97 #include "llvm/MC/MCSymbolXCOFF.h"
98 #include "llvm/MC/MCTargetOptions.h"
99 #include "llvm/MC/MCValue.h"
100 #include "llvm/MC/SectionKind.h"
101 #include "llvm/Pass.h"
102 #include "llvm/Remarks/Remark.h"
103 #include "llvm/Remarks/RemarkFormat.h"
104 #include "llvm/Remarks/RemarkStreamer.h"
105 #include "llvm/Remarks/RemarkStringTable.h"
106 #include "llvm/Support/Casting.h"
107 #include "llvm/Support/CommandLine.h"
108 #include "llvm/Support/Compiler.h"
109 #include "llvm/Support/ErrorHandling.h"
110 #include "llvm/Support/Format.h"
111 #include "llvm/Support/MathExtras.h"
112 #include "llvm/Support/Path.h"
113 #include "llvm/Support/TargetRegistry.h"
114 #include "llvm/Support/Timer.h"
115 #include "llvm/Support/raw_ostream.h"
116 #include "llvm/Target/TargetLoweringObjectFile.h"
117 #include "llvm/Target/TargetMachine.h"
118 #include "llvm/Target/TargetOptions.h"
119 #include <algorithm>
120 #include <cassert>
121 #include <cinttypes>
122 #include <cstdint>
123 #include <iterator>
124 #include <limits>
125 #include <memory>
126 #include <string>
127 #include <utility>
128 #include <vector>
129
130 using namespace llvm;
131
132 #define DEBUG_TYPE "asm-printer"
133
134 static const char *const DWARFGroupName = "dwarf";
135 static const char *const DWARFGroupDescription = "DWARF Emission";
136 static const char *const DbgTimerName = "emit";
137 static const char *const DbgTimerDescription = "Debug Info Emission";
138 static const char *const EHTimerName = "write_exception";
139 static const char *const EHTimerDescription = "DWARF Exception Writer";
140 static const char *const CFGuardName = "Control Flow Guard";
141 static const char *const CFGuardDescription = "Control Flow Guard";
142 static const char *const CodeViewLineTablesGroupName = "linetables";
143 static const char *const CodeViewLineTablesGroupDescription =
144 "CodeView Line Tables";
145
146 STATISTIC(EmittedInsts, "Number of machine instrs printed");
147
148 char AsmPrinter::ID = 0;
149
150 using gcp_map_type = DenseMap<GCStrategy *, std::unique_ptr<GCMetadataPrinter>>;
151
getGCMap(void * & P)152 static gcp_map_type &getGCMap(void *&P) {
153 if (!P)
154 P = new gcp_map_type();
155 return *(gcp_map_type*)P;
156 }
157
158 /// getGVAlignment - Return the alignment to use for the specified global
159 /// value. This rounds up to the preferred alignment if possible and legal.
getGVAlignment(const GlobalObject * GV,const DataLayout & DL,Align InAlign)160 Align AsmPrinter::getGVAlignment(const GlobalObject *GV, const DataLayout &DL,
161 Align InAlign) {
162 Align Alignment;
163 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
164 Alignment = DL.getPreferredAlign(GVar);
165
166 // If InAlign is specified, round it to it.
167 if (InAlign > Alignment)
168 Alignment = InAlign;
169
170 // If the GV has a specified alignment, take it into account.
171 const MaybeAlign GVAlign(GV->getAlignment());
172 if (!GVAlign)
173 return Alignment;
174
175 assert(GVAlign && "GVAlign must be set");
176
177 // If the GVAlign is larger than NumBits, or if we are required to obey
178 // NumBits because the GV has an assigned section, obey it.
179 if (*GVAlign > Alignment || GV->hasSection())
180 Alignment = *GVAlign;
181 return Alignment;
182 }
183
AsmPrinter(TargetMachine & tm,std::unique_ptr<MCStreamer> Streamer)184 AsmPrinter::AsmPrinter(TargetMachine &tm, std::unique_ptr<MCStreamer> Streamer)
185 : MachineFunctionPass(ID), TM(tm), MAI(tm.getMCAsmInfo()),
186 OutContext(Streamer->getContext()), OutStreamer(std::move(Streamer)) {
187 VerboseAsm = OutStreamer->isVerboseAsm();
188 }
189
~AsmPrinter()190 AsmPrinter::~AsmPrinter() {
191 assert(!DD && Handlers.empty() && "Debug/EH info didn't get finalized");
192
193 if (GCMetadataPrinters) {
194 gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
195
196 delete &GCMap;
197 GCMetadataPrinters = nullptr;
198 }
199 }
200
isPositionIndependent() const201 bool AsmPrinter::isPositionIndependent() const {
202 return TM.isPositionIndependent();
203 }
204
205 /// getFunctionNumber - Return a unique ID for the current function.
getFunctionNumber() const206 unsigned AsmPrinter::getFunctionNumber() const {
207 return MF->getFunctionNumber();
208 }
209
getObjFileLowering() const210 const TargetLoweringObjectFile &AsmPrinter::getObjFileLowering() const {
211 return *TM.getObjFileLowering();
212 }
213
getDataLayout() const214 const DataLayout &AsmPrinter::getDataLayout() const {
215 return MMI->getModule()->getDataLayout();
216 }
217
218 // Do not use the cached DataLayout because some client use it without a Module
219 // (dsymutil, llvm-dwarfdump).
getPointerSize() const220 unsigned AsmPrinter::getPointerSize() const {
221 return TM.getPointerSize(0); // FIXME: Default address space
222 }
223
getSubtargetInfo() const224 const MCSubtargetInfo &AsmPrinter::getSubtargetInfo() const {
225 assert(MF && "getSubtargetInfo requires a valid MachineFunction!");
226 return MF->getSubtarget<MCSubtargetInfo>();
227 }
228
EmitToStreamer(MCStreamer & S,const MCInst & Inst)229 void AsmPrinter::EmitToStreamer(MCStreamer &S, const MCInst &Inst) {
230 S.emitInstruction(Inst, getSubtargetInfo());
231 }
232
emitInitialRawDwarfLocDirective(const MachineFunction & MF)233 void AsmPrinter::emitInitialRawDwarfLocDirective(const MachineFunction &MF) {
234 assert(DD && "Dwarf debug file is not defined.");
235 assert(OutStreamer->hasRawTextSupport() && "Expected assembly output mode.");
236 (void)DD->emitInitialLocDirective(MF, /*CUID=*/0);
237 }
238
239 /// getCurrentSection() - Return the current section we are emitting to.
getCurrentSection() const240 const MCSection *AsmPrinter::getCurrentSection() const {
241 return OutStreamer->getCurrentSectionOnly();
242 }
243
getAnalysisUsage(AnalysisUsage & AU) const244 void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
245 AU.setPreservesAll();
246 MachineFunctionPass::getAnalysisUsage(AU);
247 AU.addRequired<MachineOptimizationRemarkEmitterPass>();
248 AU.addRequired<GCModuleInfo>();
249 }
250
doInitialization(Module & M)251 bool AsmPrinter::doInitialization(Module &M) {
252 auto *MMIWP = getAnalysisIfAvailable<MachineModuleInfoWrapperPass>();
253 MMI = MMIWP ? &MMIWP->getMMI() : nullptr;
254
255 // Initialize TargetLoweringObjectFile.
256 const_cast<TargetLoweringObjectFile&>(getObjFileLowering())
257 .Initialize(OutContext, TM);
258
259 const_cast<TargetLoweringObjectFile &>(getObjFileLowering())
260 .getModuleMetadata(M);
261
262 OutStreamer->InitSections(false);
263
264 // Emit the version-min deployment target directive if needed.
265 //
266 // FIXME: If we end up with a collection of these sorts of Darwin-specific
267 // or ELF-specific things, it may make sense to have a platform helper class
268 // that will work with the target helper class. For now keep it here, as the
269 // alternative is duplicated code in each of the target asm printers that
270 // use the directive, where it would need the same conditionalization
271 // anyway.
272 const Triple &Target = TM.getTargetTriple();
273 OutStreamer->emitVersionForTarget(Target, M.getSDKVersion());
274
275 // Allow the target to emit any magic that it wants at the start of the file.
276 emitStartOfAsmFile(M);
277
278 // Very minimal debug info. It is ignored if we emit actual debug info. If we
279 // don't, this at least helps the user find where a global came from.
280 if (MAI->hasSingleParameterDotFile()) {
281 // .file "foo.c"
282 OutStreamer->emitFileDirective(
283 llvm::sys::path::filename(M.getSourceFileName()));
284 }
285
286 GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
287 assert(MI && "AsmPrinter didn't require GCModuleInfo?");
288 for (auto &I : *MI)
289 if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(*I))
290 MP->beginAssembly(M, *MI, *this);
291
292 // Emit module-level inline asm if it exists.
293 if (!M.getModuleInlineAsm().empty()) {
294 // We're at the module level. Construct MCSubtarget from the default CPU
295 // and target triple.
296 std::unique_ptr<MCSubtargetInfo> STI(TM.getTarget().createMCSubtargetInfo(
297 TM.getTargetTriple().str(), TM.getTargetCPU(),
298 TM.getTargetFeatureString()));
299 OutStreamer->AddComment("Start of file scope inline assembly");
300 OutStreamer->AddBlankLine();
301 emitInlineAsm(M.getModuleInlineAsm() + "\n",
302 OutContext.getSubtargetCopy(*STI), TM.Options.MCOptions);
303 OutStreamer->AddComment("End of file scope inline assembly");
304 OutStreamer->AddBlankLine();
305 }
306
307 if (MAI->doesSupportDebugInformation()) {
308 bool EmitCodeView = M.getCodeViewFlag();
309 if (EmitCodeView && TM.getTargetTriple().isOSWindows()) {
310 Handlers.emplace_back(std::make_unique<CodeViewDebug>(this),
311 DbgTimerName, DbgTimerDescription,
312 CodeViewLineTablesGroupName,
313 CodeViewLineTablesGroupDescription);
314 }
315 if (!EmitCodeView || M.getDwarfVersion()) {
316 DD = new DwarfDebug(this, &M);
317 DD->beginModule();
318 Handlers.emplace_back(std::unique_ptr<DwarfDebug>(DD), DbgTimerName,
319 DbgTimerDescription, DWARFGroupName,
320 DWARFGroupDescription);
321 }
322 }
323
324 switch (MAI->getExceptionHandlingType()) {
325 case ExceptionHandling::SjLj:
326 case ExceptionHandling::DwarfCFI:
327 case ExceptionHandling::ARM:
328 isCFIMoveForDebugging = true;
329 if (MAI->getExceptionHandlingType() != ExceptionHandling::DwarfCFI)
330 break;
331 for (auto &F: M.getFunctionList()) {
332 // If the module contains any function with unwind data,
333 // .eh_frame has to be emitted.
334 // Ignore functions that won't get emitted.
335 if (!F.isDeclarationForLinker() && F.needsUnwindTableEntry()) {
336 isCFIMoveForDebugging = false;
337 break;
338 }
339 }
340 break;
341 default:
342 isCFIMoveForDebugging = false;
343 break;
344 }
345
346 EHStreamer *ES = nullptr;
347 switch (MAI->getExceptionHandlingType()) {
348 case ExceptionHandling::None:
349 break;
350 case ExceptionHandling::SjLj:
351 case ExceptionHandling::DwarfCFI:
352 ES = new DwarfCFIException(this);
353 break;
354 case ExceptionHandling::ARM:
355 ES = new ARMException(this);
356 break;
357 case ExceptionHandling::WinEH:
358 switch (MAI->getWinEHEncodingType()) {
359 default: llvm_unreachable("unsupported unwinding information encoding");
360 case WinEH::EncodingType::Invalid:
361 break;
362 case WinEH::EncodingType::X86:
363 case WinEH::EncodingType::Itanium:
364 ES = new WinException(this);
365 break;
366 }
367 break;
368 case ExceptionHandling::Wasm:
369 ES = new WasmException(this);
370 break;
371 }
372 if (ES)
373 Handlers.emplace_back(std::unique_ptr<EHStreamer>(ES), EHTimerName,
374 EHTimerDescription, DWARFGroupName,
375 DWARFGroupDescription);
376
377 // Emit tables for any value of cfguard flag (i.e. cfguard=1 or cfguard=2).
378 if (mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("cfguard")))
379 Handlers.emplace_back(std::make_unique<WinCFGuard>(this), CFGuardName,
380 CFGuardDescription, DWARFGroupName,
381 DWARFGroupDescription);
382 return false;
383 }
384
canBeHidden(const GlobalValue * GV,const MCAsmInfo & MAI)385 static bool canBeHidden(const GlobalValue *GV, const MCAsmInfo &MAI) {
386 if (!MAI.hasWeakDefCanBeHiddenDirective())
387 return false;
388
389 return GV->canBeOmittedFromSymbolTable();
390 }
391
emitLinkage(const GlobalValue * GV,MCSymbol * GVSym) const392 void AsmPrinter::emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
393 GlobalValue::LinkageTypes Linkage = GV->getLinkage();
394 switch (Linkage) {
395 case GlobalValue::CommonLinkage:
396 case GlobalValue::LinkOnceAnyLinkage:
397 case GlobalValue::LinkOnceODRLinkage:
398 case GlobalValue::WeakAnyLinkage:
399 case GlobalValue::WeakODRLinkage:
400 if (MAI->hasWeakDefDirective()) {
401 // .globl _foo
402 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
403
404 if (!canBeHidden(GV, *MAI))
405 // .weak_definition _foo
406 OutStreamer->emitSymbolAttribute(GVSym, MCSA_WeakDefinition);
407 else
408 OutStreamer->emitSymbolAttribute(GVSym, MCSA_WeakDefAutoPrivate);
409 } else if (MAI->avoidWeakIfComdat() && GV->hasComdat()) {
410 // .globl _foo
411 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
412 //NOTE: linkonce is handled by the section the symbol was assigned to.
413 } else {
414 // .weak _foo
415 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Weak);
416 }
417 return;
418 case GlobalValue::ExternalLinkage:
419 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
420 return;
421 case GlobalValue::PrivateLinkage:
422 case GlobalValue::InternalLinkage:
423 return;
424 case GlobalValue::ExternalWeakLinkage:
425 case GlobalValue::AvailableExternallyLinkage:
426 case GlobalValue::AppendingLinkage:
427 llvm_unreachable("Should never emit this");
428 }
429 llvm_unreachable("Unknown linkage type!");
430 }
431
getNameWithPrefix(SmallVectorImpl<char> & Name,const GlobalValue * GV) const432 void AsmPrinter::getNameWithPrefix(SmallVectorImpl<char> &Name,
433 const GlobalValue *GV) const {
434 TM.getNameWithPrefix(Name, GV, getObjFileLowering().getMangler());
435 }
436
getSymbol(const GlobalValue * GV) const437 MCSymbol *AsmPrinter::getSymbol(const GlobalValue *GV) const {
438 return TM.getSymbol(GV);
439 }
440
getSymbolPreferLocal(const GlobalValue & GV) const441 MCSymbol *AsmPrinter::getSymbolPreferLocal(const GlobalValue &GV) const {
442 // On ELF, use .Lfoo$local if GV is a non-interposable GlobalObject with an
443 // exact definion (intersection of GlobalValue::hasExactDefinition() and
444 // !isInterposable()). These linkages include: external, appending, internal,
445 // private. It may be profitable to use a local alias for external. The
446 // assembler would otherwise be conservative and assume a global default
447 // visibility symbol can be interposable, even if the code generator already
448 // assumed it.
449 if (TM.getTargetTriple().isOSBinFormatELF() && GV.canBenefitFromLocalAlias()) {
450 const Module &M = *GV.getParent();
451 if (TM.getRelocationModel() != Reloc::Static &&
452 M.getPIELevel() == PIELevel::Default)
453 if (GV.isDSOLocal() || (TM.getTargetTriple().isX86() &&
454 GV.getParent()->noSemanticInterposition()))
455 return getSymbolWithGlobalValueBase(&GV, "$local");
456 }
457 return TM.getSymbol(&GV);
458 }
459
460 /// EmitGlobalVariable - Emit the specified global variable to the .s file.
emitGlobalVariable(const GlobalVariable * GV)461 void AsmPrinter::emitGlobalVariable(const GlobalVariable *GV) {
462 bool IsEmuTLSVar = TM.useEmulatedTLS() && GV->isThreadLocal();
463 assert(!(IsEmuTLSVar && GV->hasCommonLinkage()) &&
464 "No emulated TLS variables in the common section");
465
466 // Never emit TLS variable xyz in emulated TLS model.
467 // The initialization value is in __emutls_t.xyz instead of xyz.
468 if (IsEmuTLSVar)
469 return;
470
471 if (GV->hasInitializer()) {
472 // Check to see if this is a special global used by LLVM, if so, emit it.
473 if (emitSpecialLLVMGlobal(GV))
474 return;
475
476 // Skip the emission of global equivalents. The symbol can be emitted later
477 // on by emitGlobalGOTEquivs in case it turns out to be needed.
478 if (GlobalGOTEquivs.count(getSymbol(GV)))
479 return;
480
481 if (isVerbose()) {
482 // When printing the control variable __emutls_v.*,
483 // we don't need to print the original TLS variable name.
484 GV->printAsOperand(OutStreamer->GetCommentOS(),
485 /*PrintType=*/false, GV->getParent());
486 OutStreamer->GetCommentOS() << '\n';
487 }
488 }
489
490 MCSymbol *GVSym = getSymbol(GV);
491 MCSymbol *EmittedSym = GVSym;
492
493 // getOrCreateEmuTLSControlSym only creates the symbol with name and default
494 // attributes.
495 // GV's or GVSym's attributes will be used for the EmittedSym.
496 emitVisibility(EmittedSym, GV->getVisibility(), !GV->isDeclaration());
497
498 if (!GV->hasInitializer()) // External globals require no extra code.
499 return;
500
501 GVSym->redefineIfPossible();
502 if (GVSym->isDefined() || GVSym->isVariable())
503 report_fatal_error("symbol '" + Twine(GVSym->getName()) +
504 "' is already defined");
505
506 if (MAI->hasDotTypeDotSizeDirective())
507 OutStreamer->emitSymbolAttribute(EmittedSym, MCSA_ELF_TypeObject);
508
509 SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
510
511 const DataLayout &DL = GV->getParent()->getDataLayout();
512 uint64_t Size = DL.getTypeAllocSize(GV->getValueType());
513
514 // If the alignment is specified, we *must* obey it. Overaligning a global
515 // with a specified alignment is a prompt way to break globals emitted to
516 // sections and expected to be contiguous (e.g. ObjC metadata).
517 const Align Alignment = getGVAlignment(GV, DL);
518
519 for (const HandlerInfo &HI : Handlers) {
520 NamedRegionTimer T(HI.TimerName, HI.TimerDescription,
521 HI.TimerGroupName, HI.TimerGroupDescription,
522 TimePassesIsEnabled);
523 HI.Handler->setSymbolSize(GVSym, Size);
524 }
525
526 // Handle common symbols
527 if (GVKind.isCommon()) {
528 if (Size == 0) Size = 1; // .comm Foo, 0 is undefined, avoid it.
529 // .comm _foo, 42, 4
530 const bool SupportsAlignment =
531 getObjFileLowering().getCommDirectiveSupportsAlignment();
532 OutStreamer->emitCommonSymbol(GVSym, Size,
533 SupportsAlignment ? Alignment.value() : 0);
534 return;
535 }
536
537 // Determine to which section this global should be emitted.
538 MCSection *TheSection = getObjFileLowering().SectionForGlobal(GV, GVKind, TM);
539
540 // If we have a bss global going to a section that supports the
541 // zerofill directive, do so here.
542 if (GVKind.isBSS() && MAI->hasMachoZeroFillDirective() &&
543 TheSection->isVirtualSection()) {
544 if (Size == 0)
545 Size = 1; // zerofill of 0 bytes is undefined.
546 emitLinkage(GV, GVSym);
547 // .zerofill __DATA, __bss, _foo, 400, 5
548 OutStreamer->emitZerofill(TheSection, GVSym, Size, Alignment.value());
549 return;
550 }
551
552 // If this is a BSS local symbol and we are emitting in the BSS
553 // section use .lcomm/.comm directive.
554 if (GVKind.isBSSLocal() &&
555 getObjFileLowering().getBSSSection() == TheSection) {
556 if (Size == 0)
557 Size = 1; // .comm Foo, 0 is undefined, avoid it.
558
559 // Use .lcomm only if it supports user-specified alignment.
560 // Otherwise, while it would still be correct to use .lcomm in some
561 // cases (e.g. when Align == 1), the external assembler might enfore
562 // some -unknown- default alignment behavior, which could cause
563 // spurious differences between external and integrated assembler.
564 // Prefer to simply fall back to .local / .comm in this case.
565 if (MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
566 // .lcomm _foo, 42
567 OutStreamer->emitLocalCommonSymbol(GVSym, Size, Alignment.value());
568 return;
569 }
570
571 // .local _foo
572 OutStreamer->emitSymbolAttribute(GVSym, MCSA_Local);
573 // .comm _foo, 42, 4
574 const bool SupportsAlignment =
575 getObjFileLowering().getCommDirectiveSupportsAlignment();
576 OutStreamer->emitCommonSymbol(GVSym, Size,
577 SupportsAlignment ? Alignment.value() : 0);
578 return;
579 }
580
581 // Handle thread local data for mach-o which requires us to output an
582 // additional structure of data and mangle the original symbol so that we
583 // can reference it later.
584 //
585 // TODO: This should become an "emit thread local global" method on TLOF.
586 // All of this macho specific stuff should be sunk down into TLOFMachO and
587 // stuff like "TLSExtraDataSection" should no longer be part of the parent
588 // TLOF class. This will also make it more obvious that stuff like
589 // MCStreamer::EmitTBSSSymbol is macho specific and only called from macho
590 // specific code.
591 if (GVKind.isThreadLocal() && MAI->hasMachoTBSSDirective()) {
592 // Emit the .tbss symbol
593 MCSymbol *MangSym =
594 OutContext.getOrCreateSymbol(GVSym->getName() + Twine("$tlv$init"));
595
596 if (GVKind.isThreadBSS()) {
597 TheSection = getObjFileLowering().getTLSBSSSection();
598 OutStreamer->emitTBSSSymbol(TheSection, MangSym, Size, Alignment.value());
599 } else if (GVKind.isThreadData()) {
600 OutStreamer->SwitchSection(TheSection);
601
602 emitAlignment(Alignment, GV);
603 OutStreamer->emitLabel(MangSym);
604
605 emitGlobalConstant(GV->getParent()->getDataLayout(),
606 GV->getInitializer());
607 }
608
609 OutStreamer->AddBlankLine();
610
611 // Emit the variable struct for the runtime.
612 MCSection *TLVSect = getObjFileLowering().getTLSExtraDataSection();
613
614 OutStreamer->SwitchSection(TLVSect);
615 // Emit the linkage here.
616 emitLinkage(GV, GVSym);
617 OutStreamer->emitLabel(GVSym);
618
619 // Three pointers in size:
620 // - __tlv_bootstrap - used to make sure support exists
621 // - spare pointer, used when mapped by the runtime
622 // - pointer to mangled symbol above with initializer
623 unsigned PtrSize = DL.getPointerTypeSize(GV->getType());
624 OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("_tlv_bootstrap"),
625 PtrSize);
626 OutStreamer->emitIntValue(0, PtrSize);
627 OutStreamer->emitSymbolValue(MangSym, PtrSize);
628
629 OutStreamer->AddBlankLine();
630 return;
631 }
632
633 MCSymbol *EmittedInitSym = GVSym;
634
635 OutStreamer->SwitchSection(TheSection);
636
637 emitLinkage(GV, EmittedInitSym);
638 emitAlignment(Alignment, GV);
639
640 OutStreamer->emitLabel(EmittedInitSym);
641 MCSymbol *LocalAlias = getSymbolPreferLocal(*GV);
642 if (LocalAlias != EmittedInitSym)
643 OutStreamer->emitLabel(LocalAlias);
644
645 emitGlobalConstant(GV->getParent()->getDataLayout(), GV->getInitializer());
646
647 if (MAI->hasDotTypeDotSizeDirective())
648 // .size foo, 42
649 OutStreamer->emitELFSize(EmittedInitSym,
650 MCConstantExpr::create(Size, OutContext));
651
652 OutStreamer->AddBlankLine();
653 }
654
655 /// Emit the directive and value for debug thread local expression
656 ///
657 /// \p Value - The value to emit.
658 /// \p Size - The size of the integer (in bytes) to emit.
emitDebugValue(const MCExpr * Value,unsigned Size) const659 void AsmPrinter::emitDebugValue(const MCExpr *Value, unsigned Size) const {
660 OutStreamer->emitValue(Value, Size);
661 }
662
emitFunctionHeaderComment()663 void AsmPrinter::emitFunctionHeaderComment() {}
664
665 /// EmitFunctionHeader - This method emits the header for the current
666 /// function.
emitFunctionHeader()667 void AsmPrinter::emitFunctionHeader() {
668 const Function &F = MF->getFunction();
669
670 if (isVerbose())
671 OutStreamer->GetCommentOS()
672 << "-- Begin function "
673 << GlobalValue::dropLLVMManglingEscape(F.getName()) << '\n';
674
675 // Print out constants referenced by the function
676 emitConstantPool();
677
678 // Print the 'header' of function.
679 MF->setSection(getObjFileLowering().SectionForGlobal(&F, TM));
680 OutStreamer->SwitchSection(MF->getSection());
681
682 if (!MAI->hasVisibilityOnlyWithLinkage())
683 emitVisibility(CurrentFnSym, F.getVisibility());
684
685 if (MAI->needsFunctionDescriptors())
686 emitLinkage(&F, CurrentFnDescSym);
687
688 emitLinkage(&F, CurrentFnSym);
689 if (MAI->hasFunctionAlignment())
690 emitAlignment(MF->getAlignment(), &F);
691
692 if (MAI->hasDotTypeDotSizeDirective())
693 OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
694
695 if (F.hasFnAttribute(Attribute::Cold))
696 OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_Cold);
697
698 if (isVerbose()) {
699 F.printAsOperand(OutStreamer->GetCommentOS(),
700 /*PrintType=*/false, F.getParent());
701 emitFunctionHeaderComment();
702 OutStreamer->GetCommentOS() << '\n';
703 }
704
705 // Emit the prefix data.
706 if (F.hasPrefixData()) {
707 if (MAI->hasSubsectionsViaSymbols()) {
708 // Preserving prefix data on platforms which use subsections-via-symbols
709 // is a bit tricky. Here we introduce a symbol for the prefix data
710 // and use the .alt_entry attribute to mark the function's real entry point
711 // as an alternative entry point to the prefix-data symbol.
712 MCSymbol *PrefixSym = OutContext.createLinkerPrivateTempSymbol();
713 OutStreamer->emitLabel(PrefixSym);
714
715 emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
716
717 // Emit an .alt_entry directive for the actual function symbol.
718 OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_AltEntry);
719 } else {
720 emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
721 }
722 }
723
724 // Emit M NOPs for -fpatchable-function-entry=N,M where M>0. We arbitrarily
725 // place prefix data before NOPs.
726 unsigned PatchableFunctionPrefix = 0;
727 unsigned PatchableFunctionEntry = 0;
728 (void)F.getFnAttribute("patchable-function-prefix")
729 .getValueAsString()
730 .getAsInteger(10, PatchableFunctionPrefix);
731 (void)F.getFnAttribute("patchable-function-entry")
732 .getValueAsString()
733 .getAsInteger(10, PatchableFunctionEntry);
734 if (PatchableFunctionPrefix) {
735 CurrentPatchableFunctionEntrySym =
736 OutContext.createLinkerPrivateTempSymbol();
737 OutStreamer->emitLabel(CurrentPatchableFunctionEntrySym);
738 emitNops(PatchableFunctionPrefix);
739 } else if (PatchableFunctionEntry) {
740 // May be reassigned when emitting the body, to reference the label after
741 // the initial BTI (AArch64) or endbr32/endbr64 (x86).
742 CurrentPatchableFunctionEntrySym = CurrentFnBegin;
743 }
744
745 // Emit the function descriptor. This is a virtual function to allow targets
746 // to emit their specific function descriptor. Right now it is only used by
747 // the AIX target. The PowerPC 64-bit V1 ELF target also uses function
748 // descriptors and should be converted to use this hook as well.
749 if (MAI->needsFunctionDescriptors())
750 emitFunctionDescriptor();
751
752 // Emit the CurrentFnSym. This is a virtual function to allow targets to do
753 // their wild and crazy things as required.
754 emitFunctionEntryLabel();
755
756 if (CurrentFnBegin) {
757 if (MAI->useAssignmentForEHBegin()) {
758 MCSymbol *CurPos = OutContext.createTempSymbol();
759 OutStreamer->emitLabel(CurPos);
760 OutStreamer->emitAssignment(CurrentFnBegin,
761 MCSymbolRefExpr::create(CurPos, OutContext));
762 } else {
763 OutStreamer->emitLabel(CurrentFnBegin);
764 }
765 }
766
767 // Emit pre-function debug and/or EH information.
768 for (const HandlerInfo &HI : Handlers) {
769 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
770 HI.TimerGroupDescription, TimePassesIsEnabled);
771 HI.Handler->beginFunction(MF);
772 }
773
774 // Emit the prologue data.
775 if (F.hasPrologueData())
776 emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrologueData());
777 }
778
779 /// EmitFunctionEntryLabel - Emit the label that is the entrypoint for the
780 /// function. This can be overridden by targets as required to do custom stuff.
emitFunctionEntryLabel()781 void AsmPrinter::emitFunctionEntryLabel() {
782 CurrentFnSym->redefineIfPossible();
783
784 // The function label could have already been emitted if two symbols end up
785 // conflicting due to asm renaming. Detect this and emit an error.
786 if (CurrentFnSym->isVariable())
787 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
788 "' is a protected alias");
789 if (CurrentFnSym->isDefined())
790 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
791 "' label emitted multiple times to assembly file");
792
793 OutStreamer->emitLabel(CurrentFnSym);
794
795 if (TM.getTargetTriple().isOSBinFormatELF()) {
796 MCSymbol *Sym = getSymbolPreferLocal(MF->getFunction());
797 if (Sym != CurrentFnSym)
798 OutStreamer->emitLabel(Sym);
799 }
800 }
801
802 /// emitComments - Pretty-print comments for instructions.
emitComments(const MachineInstr & MI,raw_ostream & CommentOS)803 static void emitComments(const MachineInstr &MI, raw_ostream &CommentOS) {
804 const MachineFunction *MF = MI.getMF();
805 const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
806
807 // Check for spills and reloads
808
809 // We assume a single instruction only has a spill or reload, not
810 // both.
811 Optional<unsigned> Size;
812 if ((Size = MI.getRestoreSize(TII))) {
813 CommentOS << *Size << "-byte Reload\n";
814 } else if ((Size = MI.getFoldedRestoreSize(TII))) {
815 if (*Size)
816 CommentOS << *Size << "-byte Folded Reload\n";
817 } else if ((Size = MI.getSpillSize(TII))) {
818 CommentOS << *Size << "-byte Spill\n";
819 } else if ((Size = MI.getFoldedSpillSize(TII))) {
820 if (*Size)
821 CommentOS << *Size << "-byte Folded Spill\n";
822 }
823
824 // Check for spill-induced copies
825 if (MI.getAsmPrinterFlag(MachineInstr::ReloadReuse))
826 CommentOS << " Reload Reuse\n";
827 }
828
829 /// emitImplicitDef - This method emits the specified machine instruction
830 /// that is an implicit def.
emitImplicitDef(const MachineInstr * MI) const831 void AsmPrinter::emitImplicitDef(const MachineInstr *MI) const {
832 Register RegNo = MI->getOperand(0).getReg();
833
834 SmallString<128> Str;
835 raw_svector_ostream OS(Str);
836 OS << "implicit-def: "
837 << printReg(RegNo, MF->getSubtarget().getRegisterInfo());
838
839 OutStreamer->AddComment(OS.str());
840 OutStreamer->AddBlankLine();
841 }
842
emitKill(const MachineInstr * MI,AsmPrinter & AP)843 static void emitKill(const MachineInstr *MI, AsmPrinter &AP) {
844 std::string Str;
845 raw_string_ostream OS(Str);
846 OS << "kill:";
847 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
848 const MachineOperand &Op = MI->getOperand(i);
849 assert(Op.isReg() && "KILL instruction must have only register operands");
850 OS << ' ' << (Op.isDef() ? "def " : "killed ")
851 << printReg(Op.getReg(), AP.MF->getSubtarget().getRegisterInfo());
852 }
853 AP.OutStreamer->AddComment(OS.str());
854 AP.OutStreamer->AddBlankLine();
855 }
856
857 /// emitDebugValueComment - This method handles the target-independent form
858 /// of DBG_VALUE, returning true if it was able to do so. A false return
859 /// means the target will need to handle MI in EmitInstruction.
emitDebugValueComment(const MachineInstr * MI,AsmPrinter & AP)860 static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
861 // This code handles only the 4-operand target-independent form.
862 if (MI->getNumOperands() != 4)
863 return false;
864
865 SmallString<128> Str;
866 raw_svector_ostream OS(Str);
867 OS << "DEBUG_VALUE: ";
868
869 const DILocalVariable *V = MI->getDebugVariable();
870 if (auto *SP = dyn_cast<DISubprogram>(V->getScope())) {
871 StringRef Name = SP->getName();
872 if (!Name.empty())
873 OS << Name << ":";
874 }
875 OS << V->getName();
876 OS << " <- ";
877
878 // The second operand is only an offset if it's an immediate.
879 bool MemLoc = MI->isIndirectDebugValue();
880 int64_t Offset = MemLoc ? MI->getOperand(1).getImm() : 0;
881 const DIExpression *Expr = MI->getDebugExpression();
882 if (Expr->getNumElements()) {
883 OS << '[';
884 bool NeedSep = false;
885 for (auto Op : Expr->expr_ops()) {
886 if (NeedSep)
887 OS << ", ";
888 else
889 NeedSep = true;
890 OS << dwarf::OperationEncodingString(Op.getOp());
891 for (unsigned I = 0; I < Op.getNumArgs(); ++I)
892 OS << ' ' << Op.getArg(I);
893 }
894 OS << "] ";
895 }
896
897 // Register or immediate value. Register 0 means undef.
898 if (MI->getDebugOperand(0).isFPImm()) {
899 APFloat APF = APFloat(MI->getDebugOperand(0).getFPImm()->getValueAPF());
900 if (MI->getDebugOperand(0).getFPImm()->getType()->isFloatTy()) {
901 OS << (double)APF.convertToFloat();
902 } else if (MI->getDebugOperand(0).getFPImm()->getType()->isDoubleTy()) {
903 OS << APF.convertToDouble();
904 } else {
905 // There is no good way to print long double. Convert a copy to
906 // double. Ah well, it's only a comment.
907 bool ignored;
908 APF.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
909 &ignored);
910 OS << "(long double) " << APF.convertToDouble();
911 }
912 } else if (MI->getDebugOperand(0).isImm()) {
913 OS << MI->getDebugOperand(0).getImm();
914 } else if (MI->getDebugOperand(0).isCImm()) {
915 MI->getDebugOperand(0).getCImm()->getValue().print(OS, false /*isSigned*/);
916 } else if (MI->getDebugOperand(0).isTargetIndex()) {
917 auto Op = MI->getDebugOperand(0);
918 OS << "!target-index(" << Op.getIndex() << "," << Op.getOffset() << ")";
919 return true;
920 } else {
921 Register Reg;
922 if (MI->getDebugOperand(0).isReg()) {
923 Reg = MI->getDebugOperand(0).getReg();
924 } else {
925 assert(MI->getDebugOperand(0).isFI() && "Unknown operand type");
926 const TargetFrameLowering *TFI = AP.MF->getSubtarget().getFrameLowering();
927 Offset += TFI->getFrameIndexReference(
928 *AP.MF, MI->getDebugOperand(0).getIndex(), Reg);
929 MemLoc = true;
930 }
931 if (Reg == 0) {
932 // Suppress offset, it is not meaningful here.
933 OS << "undef";
934 // NOTE: Want this comment at start of line, don't emit with AddComment.
935 AP.OutStreamer->emitRawComment(OS.str());
936 return true;
937 }
938 if (MemLoc)
939 OS << '[';
940 OS << printReg(Reg, AP.MF->getSubtarget().getRegisterInfo());
941 }
942
943 if (MemLoc)
944 OS << '+' << Offset << ']';
945
946 // NOTE: Want this comment at start of line, don't emit with AddComment.
947 AP.OutStreamer->emitRawComment(OS.str());
948 return true;
949 }
950
951 /// This method handles the target-independent form of DBG_LABEL, returning
952 /// true if it was able to do so. A false return means the target will need
953 /// to handle MI in EmitInstruction.
emitDebugLabelComment(const MachineInstr * MI,AsmPrinter & AP)954 static bool emitDebugLabelComment(const MachineInstr *MI, AsmPrinter &AP) {
955 if (MI->getNumOperands() != 1)
956 return false;
957
958 SmallString<128> Str;
959 raw_svector_ostream OS(Str);
960 OS << "DEBUG_LABEL: ";
961
962 const DILabel *V = MI->getDebugLabel();
963 if (auto *SP = dyn_cast<DISubprogram>(
964 V->getScope()->getNonLexicalBlockFileScope())) {
965 StringRef Name = SP->getName();
966 if (!Name.empty())
967 OS << Name << ":";
968 }
969 OS << V->getName();
970
971 // NOTE: Want this comment at start of line, don't emit with AddComment.
972 AP.OutStreamer->emitRawComment(OS.str());
973 return true;
974 }
975
needsCFIMoves() const976 AsmPrinter::CFIMoveType AsmPrinter::needsCFIMoves() const {
977 if (MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI &&
978 MF->getFunction().needsUnwindTableEntry())
979 return CFI_M_EH;
980
981 if (MMI->hasDebugInfo() || MF->getTarget().Options.ForceDwarfFrameSection)
982 return CFI_M_Debug;
983
984 return CFI_M_None;
985 }
986
needsSEHMoves()987 bool AsmPrinter::needsSEHMoves() {
988 return MAI->usesWindowsCFI() && MF->getFunction().needsUnwindTableEntry();
989 }
990
emitCFIInstruction(const MachineInstr & MI)991 void AsmPrinter::emitCFIInstruction(const MachineInstr &MI) {
992 ExceptionHandling ExceptionHandlingType = MAI->getExceptionHandlingType();
993 if (ExceptionHandlingType != ExceptionHandling::DwarfCFI &&
994 ExceptionHandlingType != ExceptionHandling::ARM)
995 return;
996
997 if (needsCFIMoves() == CFI_M_None)
998 return;
999
1000 // If there is no "real" instruction following this CFI instruction, skip
1001 // emitting it; it would be beyond the end of the function's FDE range.
1002 auto *MBB = MI.getParent();
1003 auto I = std::next(MI.getIterator());
1004 while (I != MBB->end() && I->isTransient())
1005 ++I;
1006 if (I == MBB->instr_end() &&
1007 MBB->getReverseIterator() == MBB->getParent()->rbegin())
1008 return;
1009
1010 const std::vector<MCCFIInstruction> &Instrs = MF->getFrameInstructions();
1011 unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
1012 const MCCFIInstruction &CFI = Instrs[CFIIndex];
1013 emitCFIInstruction(CFI);
1014 }
1015
emitFrameAlloc(const MachineInstr & MI)1016 void AsmPrinter::emitFrameAlloc(const MachineInstr &MI) {
1017 // The operands are the MCSymbol and the frame offset of the allocation.
1018 MCSymbol *FrameAllocSym = MI.getOperand(0).getMCSymbol();
1019 int FrameOffset = MI.getOperand(1).getImm();
1020
1021 // Emit a symbol assignment.
1022 OutStreamer->emitAssignment(FrameAllocSym,
1023 MCConstantExpr::create(FrameOffset, OutContext));
1024 }
1025
emitStackSizeSection(const MachineFunction & MF)1026 void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
1027 if (!MF.getTarget().Options.EmitStackSizeSection)
1028 return;
1029
1030 MCSection *StackSizeSection =
1031 getObjFileLowering().getStackSizesSection(*getCurrentSection());
1032 if (!StackSizeSection)
1033 return;
1034
1035 const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
1036 // Don't emit functions with dynamic stack allocations.
1037 if (FrameInfo.hasVarSizedObjects())
1038 return;
1039
1040 OutStreamer->PushSection();
1041 OutStreamer->SwitchSection(StackSizeSection);
1042
1043 const MCSymbol *FunctionSymbol = getFunctionBegin();
1044 uint64_t StackSize = FrameInfo.getStackSize();
1045 OutStreamer->emitSymbolValue(FunctionSymbol, TM.getProgramPointerSize());
1046 OutStreamer->emitULEB128IntValue(StackSize);
1047
1048 OutStreamer->PopSection();
1049 }
1050
needFuncLabelsForEHOrDebugInfo(const MachineFunction & MF)1051 static bool needFuncLabelsForEHOrDebugInfo(const MachineFunction &MF) {
1052 MachineModuleInfo &MMI = MF.getMMI();
1053 if (!MF.getLandingPads().empty() || MF.hasEHFunclets() || MMI.hasDebugInfo())
1054 return true;
1055
1056 // We might emit an EH table that uses function begin and end labels even if
1057 // we don't have any landingpads.
1058 if (!MF.getFunction().hasPersonalityFn())
1059 return false;
1060 return !isNoOpWithoutInvoke(
1061 classifyEHPersonality(MF.getFunction().getPersonalityFn()));
1062 }
1063
1064 /// EmitFunctionBody - This method emits the body and trailer for a
1065 /// function.
emitFunctionBody()1066 void AsmPrinter::emitFunctionBody() {
1067 emitFunctionHeader();
1068
1069 // Emit target-specific gunk before the function body.
1070 emitFunctionBodyStart();
1071
1072 bool ShouldPrintDebugScopes = MMI->hasDebugInfo();
1073
1074 if (isVerbose()) {
1075 // Get MachineDominatorTree or compute it on the fly if it's unavailable
1076 MDT = getAnalysisIfAvailable<MachineDominatorTree>();
1077 if (!MDT) {
1078 OwnedMDT = std::make_unique<MachineDominatorTree>();
1079 OwnedMDT->getBase().recalculate(*MF);
1080 MDT = OwnedMDT.get();
1081 }
1082
1083 // Get MachineLoopInfo or compute it on the fly if it's unavailable
1084 MLI = getAnalysisIfAvailable<MachineLoopInfo>();
1085 if (!MLI) {
1086 OwnedMLI = std::make_unique<MachineLoopInfo>();
1087 OwnedMLI->getBase().analyze(MDT->getBase());
1088 MLI = OwnedMLI.get();
1089 }
1090 }
1091
1092 // Print out code for the function.
1093 bool HasAnyRealCode = false;
1094 int NumInstsInFunction = 0;
1095
1096 for (auto &MBB : *MF) {
1097 // Print a label for the basic block.
1098 emitBasicBlockStart(MBB);
1099 for (auto &MI : MBB) {
1100 // Print the assembly for the instruction.
1101 if (!MI.isPosition() && !MI.isImplicitDef() && !MI.isKill() &&
1102 !MI.isDebugInstr()) {
1103 HasAnyRealCode = true;
1104 ++NumInstsInFunction;
1105 }
1106
1107 // If there is a pre-instruction symbol, emit a label for it here.
1108 if (MCSymbol *S = MI.getPreInstrSymbol())
1109 OutStreamer->emitLabel(S);
1110
1111 if (ShouldPrintDebugScopes) {
1112 for (const HandlerInfo &HI : Handlers) {
1113 NamedRegionTimer T(HI.TimerName, HI.TimerDescription,
1114 HI.TimerGroupName, HI.TimerGroupDescription,
1115 TimePassesIsEnabled);
1116 HI.Handler->beginInstruction(&MI);
1117 }
1118 }
1119
1120 if (isVerbose())
1121 emitComments(MI, OutStreamer->GetCommentOS());
1122
1123 switch (MI.getOpcode()) {
1124 case TargetOpcode::CFI_INSTRUCTION:
1125 emitCFIInstruction(MI);
1126 break;
1127 case TargetOpcode::LOCAL_ESCAPE:
1128 emitFrameAlloc(MI);
1129 break;
1130 case TargetOpcode::ANNOTATION_LABEL:
1131 case TargetOpcode::EH_LABEL:
1132 case TargetOpcode::GC_LABEL:
1133 OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol());
1134 break;
1135 case TargetOpcode::INLINEASM:
1136 case TargetOpcode::INLINEASM_BR:
1137 emitInlineAsm(&MI);
1138 break;
1139 case TargetOpcode::DBG_VALUE:
1140 if (isVerbose()) {
1141 if (!emitDebugValueComment(&MI, *this))
1142 emitInstruction(&MI);
1143 }
1144 break;
1145 case TargetOpcode::DBG_LABEL:
1146 if (isVerbose()) {
1147 if (!emitDebugLabelComment(&MI, *this))
1148 emitInstruction(&MI);
1149 }
1150 break;
1151 case TargetOpcode::IMPLICIT_DEF:
1152 if (isVerbose()) emitImplicitDef(&MI);
1153 break;
1154 case TargetOpcode::KILL:
1155 if (isVerbose()) emitKill(&MI, *this);
1156 break;
1157 default:
1158 emitInstruction(&MI);
1159 break;
1160 }
1161
1162 // If there is a post-instruction symbol, emit a label for it here.
1163 if (MCSymbol *S = MI.getPostInstrSymbol())
1164 OutStreamer->emitLabel(S);
1165
1166 if (ShouldPrintDebugScopes) {
1167 for (const HandlerInfo &HI : Handlers) {
1168 NamedRegionTimer T(HI.TimerName, HI.TimerDescription,
1169 HI.TimerGroupName, HI.TimerGroupDescription,
1170 TimePassesIsEnabled);
1171 HI.Handler->endInstruction();
1172 }
1173 }
1174 }
1175
1176 // We need a temporary symbol for the end of this basic block, if either we
1177 // have BBLabels enabled and we want to emit size directive for the BBs, or
1178 // if this basic blocks marks the end of a section (except the section
1179 // containing the entry basic block as the end symbol for that section is
1180 // CurrentFnEnd).
1181 MCSymbol *CurrentBBEnd = nullptr;
1182 if ((MAI->hasDotTypeDotSizeDirective() && MF->hasBBLabels()) ||
1183 (MBB.isEndSection() && !MBB.sameSection(&MF->front()))) {
1184 CurrentBBEnd = OutContext.createTempSymbol();
1185 OutStreamer->emitLabel(CurrentBBEnd);
1186 }
1187
1188 // Helper for emitting the size directive associated with a basic block
1189 // symbol.
1190 auto emitELFSizeDirective = [&](MCSymbol *SymForSize) {
1191 assert(CurrentBBEnd && "Basicblock end symbol not set!");
1192 const MCExpr *SizeExp = MCBinaryExpr::createSub(
1193 MCSymbolRefExpr::create(CurrentBBEnd, OutContext),
1194 MCSymbolRefExpr::create(SymForSize, OutContext), OutContext);
1195 OutStreamer->emitELFSize(SymForSize, SizeExp);
1196 };
1197
1198 // Emit size directive for the size of each basic block, if BBLabels is
1199 // enabled.
1200 if (MAI->hasDotTypeDotSizeDirective() && MF->hasBBLabels())
1201 emitELFSizeDirective(MBB.getSymbol());
1202
1203 // Emit size directive for the size of each basic block section once we
1204 // get to the end of that section.
1205 if (MBB.isEndSection()) {
1206 if (!MBB.sameSection(&MF->front())) {
1207 if (MAI->hasDotTypeDotSizeDirective())
1208 emitELFSizeDirective(CurrentSectionBeginSym);
1209 MBBSectionRanges[MBB.getSectionIDNum()] =
1210 MBBSectionRange{CurrentSectionBeginSym, CurrentBBEnd};
1211 }
1212 }
1213 emitBasicBlockEnd(MBB);
1214 }
1215
1216 EmittedInsts += NumInstsInFunction;
1217 MachineOptimizationRemarkAnalysis R(DEBUG_TYPE, "InstructionCount",
1218 MF->getFunction().getSubprogram(),
1219 &MF->front());
1220 R << ore::NV("NumInstructions", NumInstsInFunction)
1221 << " instructions in function";
1222 ORE->emit(R);
1223
1224 // If the function is empty and the object file uses .subsections_via_symbols,
1225 // then we need to emit *something* to the function body to prevent the
1226 // labels from collapsing together. Just emit a noop.
1227 // Similarly, don't emit empty functions on Windows either. It can lead to
1228 // duplicate entries (two functions with the same RVA) in the Guard CF Table
1229 // after linking, causing the kernel not to load the binary:
1230 // https://developercommunity.visualstudio.com/content/problem/45366/vc-linker-creates-invalid-dll-with-clang-cl.html
1231 // FIXME: Hide this behind some API in e.g. MCAsmInfo or MCTargetStreamer.
1232 const Triple &TT = TM.getTargetTriple();
1233 if (!HasAnyRealCode && (MAI->hasSubsectionsViaSymbols() ||
1234 (TT.isOSWindows() && TT.isOSBinFormatCOFF()))) {
1235 MCInst Noop;
1236 MF->getSubtarget().getInstrInfo()->getNoop(Noop);
1237
1238 // Targets can opt-out of emitting the noop here by leaving the opcode
1239 // unspecified.
1240 if (Noop.getOpcode()) {
1241 OutStreamer->AddComment("avoids zero-length function");
1242 emitNops(1);
1243 }
1244 }
1245
1246 // Switch to the original section in case basic block sections was used.
1247 OutStreamer->SwitchSection(MF->getSection());
1248
1249 const Function &F = MF->getFunction();
1250 for (const auto &BB : F) {
1251 if (!BB.hasAddressTaken())
1252 continue;
1253 MCSymbol *Sym = GetBlockAddressSymbol(&BB);
1254 if (Sym->isDefined())
1255 continue;
1256 OutStreamer->AddComment("Address of block that was removed by CodeGen");
1257 OutStreamer->emitLabel(Sym);
1258 }
1259
1260 // Emit target-specific gunk after the function body.
1261 emitFunctionBodyEnd();
1262
1263 if (needFuncLabelsForEHOrDebugInfo(*MF) ||
1264 MAI->hasDotTypeDotSizeDirective()) {
1265 // Create a symbol for the end of function.
1266 CurrentFnEnd = createTempSymbol("func_end");
1267 OutStreamer->emitLabel(CurrentFnEnd);
1268 }
1269
1270 // If the target wants a .size directive for the size of the function, emit
1271 // it.
1272 if (MAI->hasDotTypeDotSizeDirective()) {
1273 // We can get the size as difference between the function label and the
1274 // temp label.
1275 const MCExpr *SizeExp = MCBinaryExpr::createSub(
1276 MCSymbolRefExpr::create(CurrentFnEnd, OutContext),
1277 MCSymbolRefExpr::create(CurrentFnSymForSize, OutContext), OutContext);
1278 OutStreamer->emitELFSize(CurrentFnSym, SizeExp);
1279 }
1280
1281 for (const HandlerInfo &HI : Handlers) {
1282 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1283 HI.TimerGroupDescription, TimePassesIsEnabled);
1284 HI.Handler->markFunctionEnd();
1285 }
1286
1287 MBBSectionRanges[MF->front().getSectionIDNum()] =
1288 MBBSectionRange{CurrentFnBegin, CurrentFnEnd};
1289
1290 // Print out jump tables referenced by the function.
1291 emitJumpTableInfo();
1292
1293 // Emit post-function debug and/or EH information.
1294 for (const HandlerInfo &HI : Handlers) {
1295 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1296 HI.TimerGroupDescription, TimePassesIsEnabled);
1297 HI.Handler->endFunction(MF);
1298 }
1299
1300 // Emit section containing stack size metadata.
1301 emitStackSizeSection(*MF);
1302
1303 emitPatchableFunctionEntries();
1304
1305 if (isVerbose())
1306 OutStreamer->GetCommentOS() << "-- End function\n";
1307
1308 OutStreamer->AddBlankLine();
1309 }
1310
1311 /// Compute the number of Global Variables that uses a Constant.
getNumGlobalVariableUses(const Constant * C)1312 static unsigned getNumGlobalVariableUses(const Constant *C) {
1313 if (!C)
1314 return 0;
1315
1316 if (isa<GlobalVariable>(C))
1317 return 1;
1318
1319 unsigned NumUses = 0;
1320 for (auto *CU : C->users())
1321 NumUses += getNumGlobalVariableUses(dyn_cast<Constant>(CU));
1322
1323 return NumUses;
1324 }
1325
1326 /// Only consider global GOT equivalents if at least one user is a
1327 /// cstexpr inside an initializer of another global variables. Also, don't
1328 /// handle cstexpr inside instructions. During global variable emission,
1329 /// candidates are skipped and are emitted later in case at least one cstexpr
1330 /// isn't replaced by a PC relative GOT entry access.
isGOTEquivalentCandidate(const GlobalVariable * GV,unsigned & NumGOTEquivUsers)1331 static bool isGOTEquivalentCandidate(const GlobalVariable *GV,
1332 unsigned &NumGOTEquivUsers) {
1333 // Global GOT equivalents are unnamed private globals with a constant
1334 // pointer initializer to another global symbol. They must point to a
1335 // GlobalVariable or Function, i.e., as GlobalValue.
1336 if (!GV->hasGlobalUnnamedAddr() || !GV->hasInitializer() ||
1337 !GV->isConstant() || !GV->isDiscardableIfUnused() ||
1338 !isa<GlobalValue>(GV->getOperand(0)))
1339 return false;
1340
1341 // To be a got equivalent, at least one of its users need to be a constant
1342 // expression used by another global variable.
1343 for (auto *U : GV->users())
1344 NumGOTEquivUsers += getNumGlobalVariableUses(dyn_cast<Constant>(U));
1345
1346 return NumGOTEquivUsers > 0;
1347 }
1348
1349 /// Unnamed constant global variables solely contaning a pointer to
1350 /// another globals variable is equivalent to a GOT table entry; it contains the
1351 /// the address of another symbol. Optimize it and replace accesses to these
1352 /// "GOT equivalents" by using the GOT entry for the final global instead.
1353 /// Compute GOT equivalent candidates among all global variables to avoid
1354 /// emitting them if possible later on, after it use is replaced by a GOT entry
1355 /// access.
computeGlobalGOTEquivs(Module & M)1356 void AsmPrinter::computeGlobalGOTEquivs(Module &M) {
1357 if (!getObjFileLowering().supportIndirectSymViaGOTPCRel())
1358 return;
1359
1360 for (const auto &G : M.globals()) {
1361 unsigned NumGOTEquivUsers = 0;
1362 if (!isGOTEquivalentCandidate(&G, NumGOTEquivUsers))
1363 continue;
1364
1365 const MCSymbol *GOTEquivSym = getSymbol(&G);
1366 GlobalGOTEquivs[GOTEquivSym] = std::make_pair(&G, NumGOTEquivUsers);
1367 }
1368 }
1369
1370 /// Constant expressions using GOT equivalent globals may not be eligible
1371 /// for PC relative GOT entry conversion, in such cases we need to emit such
1372 /// globals we previously omitted in EmitGlobalVariable.
emitGlobalGOTEquivs()1373 void AsmPrinter::emitGlobalGOTEquivs() {
1374 if (!getObjFileLowering().supportIndirectSymViaGOTPCRel())
1375 return;
1376
1377 SmallVector<const GlobalVariable *, 8> FailedCandidates;
1378 for (auto &I : GlobalGOTEquivs) {
1379 const GlobalVariable *GV = I.second.first;
1380 unsigned Cnt = I.second.second;
1381 if (Cnt)
1382 FailedCandidates.push_back(GV);
1383 }
1384 GlobalGOTEquivs.clear();
1385
1386 for (auto *GV : FailedCandidates)
1387 emitGlobalVariable(GV);
1388 }
1389
emitGlobalIndirectSymbol(Module & M,const GlobalIndirectSymbol & GIS)1390 void AsmPrinter::emitGlobalIndirectSymbol(Module &M,
1391 const GlobalIndirectSymbol& GIS) {
1392 MCSymbol *Name = getSymbol(&GIS);
1393
1394 if (GIS.hasExternalLinkage() || !MAI->getWeakRefDirective())
1395 OutStreamer->emitSymbolAttribute(Name, MCSA_Global);
1396 else if (GIS.hasWeakLinkage() || GIS.hasLinkOnceLinkage())
1397 OutStreamer->emitSymbolAttribute(Name, MCSA_WeakReference);
1398 else
1399 assert(GIS.hasLocalLinkage() && "Invalid alias or ifunc linkage");
1400
1401 bool IsFunction = GIS.getValueType()->isFunctionTy();
1402
1403 // Treat bitcasts of functions as functions also. This is important at least
1404 // on WebAssembly where object and function addresses can't alias each other.
1405 if (!IsFunction)
1406 if (auto *CE = dyn_cast<ConstantExpr>(GIS.getIndirectSymbol()))
1407 if (CE->getOpcode() == Instruction::BitCast)
1408 IsFunction =
1409 CE->getOperand(0)->getType()->getPointerElementType()->isFunctionTy();
1410
1411 // Set the symbol type to function if the alias has a function type.
1412 // This affects codegen when the aliasee is not a function.
1413 if (IsFunction)
1414 OutStreamer->emitSymbolAttribute(Name, isa<GlobalIFunc>(GIS)
1415 ? MCSA_ELF_TypeIndFunction
1416 : MCSA_ELF_TypeFunction);
1417
1418 emitVisibility(Name, GIS.getVisibility());
1419
1420 const MCExpr *Expr = lowerConstant(GIS.getIndirectSymbol());
1421
1422 if (isa<GlobalAlias>(&GIS) && MAI->hasAltEntry() && isa<MCBinaryExpr>(Expr))
1423 OutStreamer->emitSymbolAttribute(Name, MCSA_AltEntry);
1424
1425 // Emit the directives as assignments aka .set:
1426 OutStreamer->emitAssignment(Name, Expr);
1427 MCSymbol *LocalAlias = getSymbolPreferLocal(GIS);
1428 if (LocalAlias != Name)
1429 OutStreamer->emitAssignment(LocalAlias, Expr);
1430
1431 if (auto *GA = dyn_cast<GlobalAlias>(&GIS)) {
1432 // If the aliasee does not correspond to a symbol in the output, i.e. the
1433 // alias is not of an object or the aliased object is private, then set the
1434 // size of the alias symbol from the type of the alias. We don't do this in
1435 // other situations as the alias and aliasee having differing types but same
1436 // size may be intentional.
1437 const GlobalObject *BaseObject = GA->getBaseObject();
1438 if (MAI->hasDotTypeDotSizeDirective() && GA->getValueType()->isSized() &&
1439 (!BaseObject || BaseObject->hasPrivateLinkage())) {
1440 const DataLayout &DL = M.getDataLayout();
1441 uint64_t Size = DL.getTypeAllocSize(GA->getValueType());
1442 OutStreamer->emitELFSize(Name, MCConstantExpr::create(Size, OutContext));
1443 }
1444 }
1445 }
1446
emitRemarksSection(remarks::RemarkStreamer & RS)1447 void AsmPrinter::emitRemarksSection(remarks::RemarkStreamer &RS) {
1448 if (!RS.needsSection())
1449 return;
1450
1451 remarks::RemarkSerializer &RemarkSerializer = RS.getSerializer();
1452
1453 Optional<SmallString<128>> Filename;
1454 if (Optional<StringRef> FilenameRef = RS.getFilename()) {
1455 Filename = *FilenameRef;
1456 sys::fs::make_absolute(*Filename);
1457 assert(!Filename->empty() && "The filename can't be empty.");
1458 }
1459
1460 std::string Buf;
1461 raw_string_ostream OS(Buf);
1462 std::unique_ptr<remarks::MetaSerializer> MetaSerializer =
1463 Filename ? RemarkSerializer.metaSerializer(OS, StringRef(*Filename))
1464 : RemarkSerializer.metaSerializer(OS);
1465 MetaSerializer->emit();
1466
1467 // Switch to the remarks section.
1468 MCSection *RemarksSection =
1469 OutContext.getObjectFileInfo()->getRemarksSection();
1470 OutStreamer->SwitchSection(RemarksSection);
1471
1472 OutStreamer->emitBinaryData(OS.str());
1473 }
1474
doFinalization(Module & M)1475 bool AsmPrinter::doFinalization(Module &M) {
1476 // Set the MachineFunction to nullptr so that we can catch attempted
1477 // accesses to MF specific features at the module level and so that
1478 // we can conditionalize accesses based on whether or not it is nullptr.
1479 MF = nullptr;
1480
1481 // Gather all GOT equivalent globals in the module. We really need two
1482 // passes over the globals: one to compute and another to avoid its emission
1483 // in EmitGlobalVariable, otherwise we would not be able to handle cases
1484 // where the got equivalent shows up before its use.
1485 computeGlobalGOTEquivs(M);
1486
1487 // Emit global variables.
1488 for (const auto &G : M.globals())
1489 emitGlobalVariable(&G);
1490
1491 // Emit remaining GOT equivalent globals.
1492 emitGlobalGOTEquivs();
1493
1494 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
1495
1496 // Emit linkage(XCOFF) and visibility info for declarations
1497 for (const Function &F : M) {
1498 if (!F.isDeclarationForLinker())
1499 continue;
1500
1501 MCSymbol *Name = getSymbol(&F);
1502 // Function getSymbol gives us the function descriptor symbol for XCOFF.
1503
1504 if (!TM.getTargetTriple().isOSBinFormatXCOFF()) {
1505 GlobalValue::VisibilityTypes V = F.getVisibility();
1506 if (V == GlobalValue::DefaultVisibility)
1507 continue;
1508
1509 emitVisibility(Name, V, false);
1510 continue;
1511 }
1512
1513 if (F.isIntrinsic())
1514 continue;
1515
1516 // Handle the XCOFF case.
1517 // Variable `Name` is the function descriptor symbol (see above). Get the
1518 // function entry point symbol.
1519 MCSymbol *FnEntryPointSym = TLOF.getFunctionEntryPointSymbol(&F, TM);
1520 if (cast<MCSymbolXCOFF>(FnEntryPointSym)->hasRepresentedCsectSet())
1521 // Emit linkage for the function entry point.
1522 emitLinkage(&F, FnEntryPointSym);
1523
1524 // Emit linkage for the function descriptor.
1525 emitLinkage(&F, Name);
1526 }
1527
1528 // Emit the remarks section contents.
1529 // FIXME: Figure out when is the safest time to emit this section. It should
1530 // not come after debug info.
1531 if (remarks::RemarkStreamer *RS = M.getContext().getMainRemarkStreamer())
1532 emitRemarksSection(*RS);
1533
1534 TLOF.emitModuleMetadata(*OutStreamer, M);
1535
1536 if (TM.getTargetTriple().isOSBinFormatELF()) {
1537 MachineModuleInfoELF &MMIELF = MMI->getObjFileInfo<MachineModuleInfoELF>();
1538
1539 // Output stubs for external and common global variables.
1540 MachineModuleInfoELF::SymbolListTy Stubs = MMIELF.GetGVStubList();
1541 if (!Stubs.empty()) {
1542 OutStreamer->SwitchSection(TLOF.getDataSection());
1543 const DataLayout &DL = M.getDataLayout();
1544
1545 emitAlignment(Align(DL.getPointerSize()));
1546 for (const auto &Stub : Stubs) {
1547 OutStreamer->emitLabel(Stub.first);
1548 OutStreamer->emitSymbolValue(Stub.second.getPointer(),
1549 DL.getPointerSize());
1550 }
1551 }
1552 }
1553
1554 if (TM.getTargetTriple().isOSBinFormatCOFF()) {
1555 MachineModuleInfoCOFF &MMICOFF =
1556 MMI->getObjFileInfo<MachineModuleInfoCOFF>();
1557
1558 // Output stubs for external and common global variables.
1559 MachineModuleInfoCOFF::SymbolListTy Stubs = MMICOFF.GetGVStubList();
1560 if (!Stubs.empty()) {
1561 const DataLayout &DL = M.getDataLayout();
1562
1563 for (const auto &Stub : Stubs) {
1564 SmallString<256> SectionName = StringRef(".rdata$");
1565 SectionName += Stub.first->getName();
1566 OutStreamer->SwitchSection(OutContext.getCOFFSection(
1567 SectionName,
1568 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
1569 COFF::IMAGE_SCN_LNK_COMDAT,
1570 SectionKind::getReadOnly(), Stub.first->getName(),
1571 COFF::IMAGE_COMDAT_SELECT_ANY));
1572 emitAlignment(Align(DL.getPointerSize()));
1573 OutStreamer->emitSymbolAttribute(Stub.first, MCSA_Global);
1574 OutStreamer->emitLabel(Stub.first);
1575 OutStreamer->emitSymbolValue(Stub.second.getPointer(),
1576 DL.getPointerSize());
1577 }
1578 }
1579 }
1580
1581 // Finalize debug and EH information.
1582 for (const HandlerInfo &HI : Handlers) {
1583 NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
1584 HI.TimerGroupDescription, TimePassesIsEnabled);
1585 HI.Handler->endModule();
1586 }
1587 Handlers.clear();
1588 DD = nullptr;
1589
1590 // If the target wants to know about weak references, print them all.
1591 if (MAI->getWeakRefDirective()) {
1592 // FIXME: This is not lazy, it would be nice to only print weak references
1593 // to stuff that is actually used. Note that doing so would require targets
1594 // to notice uses in operands (due to constant exprs etc). This should
1595 // happen with the MC stuff eventually.
1596
1597 // Print out module-level global objects here.
1598 for (const auto &GO : M.global_objects()) {
1599 if (!GO.hasExternalWeakLinkage())
1600 continue;
1601 OutStreamer->emitSymbolAttribute(getSymbol(&GO), MCSA_WeakReference);
1602 }
1603 }
1604
1605 // Print aliases in topological order, that is, for each alias a = b,
1606 // b must be printed before a.
1607 // This is because on some targets (e.g. PowerPC) linker expects aliases in
1608 // such an order to generate correct TOC information.
1609 SmallVector<const GlobalAlias *, 16> AliasStack;
1610 SmallPtrSet<const GlobalAlias *, 16> AliasVisited;
1611 for (const auto &Alias : M.aliases()) {
1612 for (const GlobalAlias *Cur = &Alias; Cur;
1613 Cur = dyn_cast<GlobalAlias>(Cur->getAliasee())) {
1614 if (!AliasVisited.insert(Cur).second)
1615 break;
1616 AliasStack.push_back(Cur);
1617 }
1618 for (const GlobalAlias *AncestorAlias : llvm::reverse(AliasStack))
1619 emitGlobalIndirectSymbol(M, *AncestorAlias);
1620 AliasStack.clear();
1621 }
1622 for (const auto &IFunc : M.ifuncs())
1623 emitGlobalIndirectSymbol(M, IFunc);
1624
1625 GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
1626 assert(MI && "AsmPrinter didn't require GCModuleInfo?");
1627 for (GCModuleInfo::iterator I = MI->end(), E = MI->begin(); I != E; )
1628 if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(**--I))
1629 MP->finishAssembly(M, *MI, *this);
1630
1631 // Emit llvm.ident metadata in an '.ident' directive.
1632 emitModuleIdents(M);
1633
1634 // Emit bytes for llvm.commandline metadata.
1635 emitModuleCommandLines(M);
1636
1637 // Emit __morestack address if needed for indirect calls.
1638 if (MMI->usesMorestackAddr()) {
1639 Align Alignment(1);
1640 MCSection *ReadOnlySection = getObjFileLowering().getSectionForConstant(
1641 getDataLayout(), SectionKind::getReadOnly(),
1642 /*C=*/nullptr, Alignment);
1643 OutStreamer->SwitchSection(ReadOnlySection);
1644
1645 MCSymbol *AddrSymbol =
1646 OutContext.getOrCreateSymbol(StringRef("__morestack_addr"));
1647 OutStreamer->emitLabel(AddrSymbol);
1648
1649 unsigned PtrSize = MAI->getCodePointerSize();
1650 OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("__morestack"),
1651 PtrSize);
1652 }
1653
1654 // Emit .note.GNU-split-stack and .note.GNU-no-split-stack sections if
1655 // split-stack is used.
1656 if (TM.getTargetTriple().isOSBinFormatELF() && MMI->hasSplitStack()) {
1657 OutStreamer->SwitchSection(
1658 OutContext.getELFSection(".note.GNU-split-stack", ELF::SHT_PROGBITS, 0));
1659 if (MMI->hasNosplitStack())
1660 OutStreamer->SwitchSection(
1661 OutContext.getELFSection(".note.GNU-no-split-stack", ELF::SHT_PROGBITS, 0));
1662 }
1663
1664 // If we don't have any trampolines, then we don't require stack memory
1665 // to be executable. Some targets have a directive to declare this.
1666 Function *InitTrampolineIntrinsic = M.getFunction("llvm.init.trampoline");
1667 if (!InitTrampolineIntrinsic || InitTrampolineIntrinsic->use_empty())
1668 if (MCSection *S = MAI->getNonexecutableStackSection(OutContext))
1669 OutStreamer->SwitchSection(S);
1670
1671 if (TM.getTargetTriple().isOSBinFormatCOFF()) {
1672 // Emit /EXPORT: flags for each exported global as necessary.
1673 const auto &TLOF = getObjFileLowering();
1674 std::string Flags;
1675
1676 for (const GlobalValue &GV : M.global_values()) {
1677 raw_string_ostream OS(Flags);
1678 TLOF.emitLinkerFlagsForGlobal(OS, &GV);
1679 OS.flush();
1680 if (!Flags.empty()) {
1681 OutStreamer->SwitchSection(TLOF.getDrectveSection());
1682 OutStreamer->emitBytes(Flags);
1683 }
1684 Flags.clear();
1685 }
1686
1687 // Emit /INCLUDE: flags for each used global as necessary.
1688 if (const auto *LU = M.getNamedGlobal("llvm.used")) {
1689 assert(LU->hasInitializer() &&
1690 "expected llvm.used to have an initializer");
1691 assert(isa<ArrayType>(LU->getValueType()) &&
1692 "expected llvm.used to be an array type");
1693 if (const auto *A = cast<ConstantArray>(LU->getInitializer())) {
1694 for (const Value *Op : A->operands()) {
1695 const auto *GV = cast<GlobalValue>(Op->stripPointerCasts());
1696 // Global symbols with internal or private linkage are not visible to
1697 // the linker, and thus would cause an error when the linker tried to
1698 // preserve the symbol due to the `/include:` directive.
1699 if (GV->hasLocalLinkage())
1700 continue;
1701
1702 raw_string_ostream OS(Flags);
1703 TLOF.emitLinkerFlagsForUsed(OS, GV);
1704 OS.flush();
1705
1706 if (!Flags.empty()) {
1707 OutStreamer->SwitchSection(TLOF.getDrectveSection());
1708 OutStreamer->emitBytes(Flags);
1709 }
1710 Flags.clear();
1711 }
1712 }
1713 }
1714 }
1715
1716 if (TM.Options.EmitAddrsig) {
1717 // Emit address-significance attributes for all globals.
1718 OutStreamer->emitAddrsig();
1719 for (const GlobalValue &GV : M.global_values())
1720 if (!GV.use_empty() && !GV.isThreadLocal() &&
1721 !GV.hasDLLImportStorageClass() && !GV.getName().startswith("llvm.") &&
1722 !GV.hasAtLeastLocalUnnamedAddr())
1723 OutStreamer->emitAddrsigSym(getSymbol(&GV));
1724 }
1725
1726 // Emit symbol partition specifications (ELF only).
1727 if (TM.getTargetTriple().isOSBinFormatELF()) {
1728 unsigned UniqueID = 0;
1729 for (const GlobalValue &GV : M.global_values()) {
1730 if (!GV.hasPartition() || GV.isDeclarationForLinker() ||
1731 GV.getVisibility() != GlobalValue::DefaultVisibility)
1732 continue;
1733
1734 OutStreamer->SwitchSection(
1735 OutContext.getELFSection(".llvm_sympart", ELF::SHT_LLVM_SYMPART, 0, 0,
1736 "", ++UniqueID, nullptr));
1737 OutStreamer->emitBytes(GV.getPartition());
1738 OutStreamer->emitZeros(1);
1739 OutStreamer->emitValue(
1740 MCSymbolRefExpr::create(getSymbol(&GV), OutContext),
1741 MAI->getCodePointerSize());
1742 }
1743 }
1744
1745 // Allow the target to emit any magic that it wants at the end of the file,
1746 // after everything else has gone out.
1747 emitEndOfAsmFile(M);
1748
1749 MMI = nullptr;
1750
1751 OutStreamer->Finish();
1752 OutStreamer->reset();
1753 OwnedMLI.reset();
1754 OwnedMDT.reset();
1755
1756 return false;
1757 }
1758
getCurExceptionSym()1759 MCSymbol *AsmPrinter::getCurExceptionSym() {
1760 if (!CurExceptionSym)
1761 CurExceptionSym = createTempSymbol("exception");
1762 return CurExceptionSym;
1763 }
1764
SetupMachineFunction(MachineFunction & MF)1765 void AsmPrinter::SetupMachineFunction(MachineFunction &MF) {
1766 this->MF = &MF;
1767 const Function &F = MF.getFunction();
1768
1769 // Get the function symbol.
1770 if (!MAI->needsFunctionDescriptors()) {
1771 CurrentFnSym = getSymbol(&MF.getFunction());
1772 } else {
1773 assert(TM.getTargetTriple().isOSAIX() &&
1774 "Only AIX uses the function descriptor hooks.");
1775 // AIX is unique here in that the name of the symbol emitted for the
1776 // function body does not have the same name as the source function's
1777 // C-linkage name.
1778 assert(CurrentFnDescSym && "The function descriptor symbol needs to be"
1779 " initalized first.");
1780
1781 // Get the function entry point symbol.
1782 CurrentFnSym = getObjFileLowering().getFunctionEntryPointSymbol(&F, TM);
1783 }
1784
1785 CurrentFnSymForSize = CurrentFnSym;
1786 CurrentFnBegin = nullptr;
1787 CurrentSectionBeginSym = nullptr;
1788 MBBSectionRanges.clear();
1789 CurExceptionSym = nullptr;
1790 bool NeedsLocalForSize = MAI->needsLocalForSize();
1791 if (F.hasFnAttribute("patchable-function-entry") ||
1792 F.hasFnAttribute("function-instrument") ||
1793 F.hasFnAttribute("xray-instruction-threshold") ||
1794 needFuncLabelsForEHOrDebugInfo(MF) || NeedsLocalForSize ||
1795 MF.getTarget().Options.EmitStackSizeSection) {
1796 CurrentFnBegin = createTempSymbol("func_begin");
1797 if (NeedsLocalForSize)
1798 CurrentFnSymForSize = CurrentFnBegin;
1799 }
1800
1801 ORE = &getAnalysis<MachineOptimizationRemarkEmitterPass>().getORE();
1802 }
1803
1804 namespace {
1805
1806 // Keep track the alignment, constpool entries per Section.
1807 struct SectionCPs {
1808 MCSection *S;
1809 Align Alignment;
1810 SmallVector<unsigned, 4> CPEs;
1811
SectionCPs__anonba6972d50211::SectionCPs1812 SectionCPs(MCSection *s, Align a) : S(s), Alignment(a) {}
1813 };
1814
1815 } // end anonymous namespace
1816
1817 /// EmitConstantPool - Print to the current output stream assembly
1818 /// representations of the constants in the constant pool MCP. This is
1819 /// used to print out constants which have been "spilled to memory" by
1820 /// the code generator.
emitConstantPool()1821 void AsmPrinter::emitConstantPool() {
1822 const MachineConstantPool *MCP = MF->getConstantPool();
1823 const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
1824 if (CP.empty()) return;
1825
1826 // Calculate sections for constant pool entries. We collect entries to go into
1827 // the same section together to reduce amount of section switch statements.
1828 SmallVector<SectionCPs, 4> CPSections;
1829 for (unsigned i = 0, e = CP.size(); i != e; ++i) {
1830 const MachineConstantPoolEntry &CPE = CP[i];
1831 Align Alignment = CPE.getAlign();
1832
1833 SectionKind Kind = CPE.getSectionKind(&getDataLayout());
1834
1835 const Constant *C = nullptr;
1836 if (!CPE.isMachineConstantPoolEntry())
1837 C = CPE.Val.ConstVal;
1838
1839 MCSection *S = getObjFileLowering().getSectionForConstant(
1840 getDataLayout(), Kind, C, Alignment);
1841
1842 // The number of sections are small, just do a linear search from the
1843 // last section to the first.
1844 bool Found = false;
1845 unsigned SecIdx = CPSections.size();
1846 while (SecIdx != 0) {
1847 if (CPSections[--SecIdx].S == S) {
1848 Found = true;
1849 break;
1850 }
1851 }
1852 if (!Found) {
1853 SecIdx = CPSections.size();
1854 CPSections.push_back(SectionCPs(S, Alignment));
1855 }
1856
1857 if (Alignment > CPSections[SecIdx].Alignment)
1858 CPSections[SecIdx].Alignment = Alignment;
1859 CPSections[SecIdx].CPEs.push_back(i);
1860 }
1861
1862 // Now print stuff into the calculated sections.
1863 const MCSection *CurSection = nullptr;
1864 unsigned Offset = 0;
1865 for (unsigned i = 0, e = CPSections.size(); i != e; ++i) {
1866 for (unsigned j = 0, ee = CPSections[i].CPEs.size(); j != ee; ++j) {
1867 unsigned CPI = CPSections[i].CPEs[j];
1868 MCSymbol *Sym = GetCPISymbol(CPI);
1869 if (!Sym->isUndefined())
1870 continue;
1871
1872 if (CurSection != CPSections[i].S) {
1873 OutStreamer->SwitchSection(CPSections[i].S);
1874 emitAlignment(Align(CPSections[i].Alignment));
1875 CurSection = CPSections[i].S;
1876 Offset = 0;
1877 }
1878
1879 MachineConstantPoolEntry CPE = CP[CPI];
1880
1881 // Emit inter-object padding for alignment.
1882 unsigned NewOffset = alignTo(Offset, CPE.getAlign());
1883 OutStreamer->emitZeros(NewOffset - Offset);
1884
1885 Type *Ty = CPE.getType();
1886 Offset = NewOffset + getDataLayout().getTypeAllocSize(Ty);
1887
1888 OutStreamer->emitLabel(Sym);
1889 if (CPE.isMachineConstantPoolEntry())
1890 emitMachineConstantPoolValue(CPE.Val.MachineCPVal);
1891 else
1892 emitGlobalConstant(getDataLayout(), CPE.Val.ConstVal);
1893 }
1894 }
1895 }
1896
1897 // Print assembly representations of the jump tables used by the current
1898 // function.
emitJumpTableInfo()1899 void AsmPrinter::emitJumpTableInfo() {
1900 const DataLayout &DL = MF->getDataLayout();
1901 const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
1902 if (!MJTI) return;
1903 if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
1904 const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
1905 if (JT.empty()) return;
1906
1907 // Pick the directive to use to print the jump table entries, and switch to
1908 // the appropriate section.
1909 const Function &F = MF->getFunction();
1910 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
1911 bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
1912 MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32,
1913 F);
1914 if (JTInDiffSection) {
1915 // Drop it in the readonly section.
1916 MCSection *ReadOnlySection = TLOF.getSectionForJumpTable(F, TM);
1917 OutStreamer->SwitchSection(ReadOnlySection);
1918 }
1919
1920 emitAlignment(Align(MJTI->getEntryAlignment(DL)));
1921
1922 // Jump tables in code sections are marked with a data_region directive
1923 // where that's supported.
1924 if (!JTInDiffSection)
1925 OutStreamer->emitDataRegion(MCDR_DataRegionJT32);
1926
1927 for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
1928 const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
1929
1930 // If this jump table was deleted, ignore it.
1931 if (JTBBs.empty()) continue;
1932
1933 // For the EK_LabelDifference32 entry, if using .set avoids a relocation,
1934 /// emit a .set directive for each unique entry.
1935 if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
1936 MAI->doesSetDirectiveSuppressReloc()) {
1937 SmallPtrSet<const MachineBasicBlock*, 16> EmittedSets;
1938 const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
1939 const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF,JTI,OutContext);
1940 for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
1941 const MachineBasicBlock *MBB = JTBBs[ii];
1942 if (!EmittedSets.insert(MBB).second)
1943 continue;
1944
1945 // .set LJTSet, LBB32-base
1946 const MCExpr *LHS =
1947 MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
1948 OutStreamer->emitAssignment(GetJTSetSymbol(JTI, MBB->getNumber()),
1949 MCBinaryExpr::createSub(LHS, Base,
1950 OutContext));
1951 }
1952 }
1953
1954 // On some targets (e.g. Darwin) we want to emit two consecutive labels
1955 // before each jump table. The first label is never referenced, but tells
1956 // the assembler and linker the extents of the jump table object. The
1957 // second label is actually referenced by the code.
1958 if (JTInDiffSection && DL.hasLinkerPrivateGlobalPrefix())
1959 // FIXME: This doesn't have to have any specific name, just any randomly
1960 // named and numbered local label started with 'l' would work. Simplify
1961 // GetJTISymbol.
1962 OutStreamer->emitLabel(GetJTISymbol(JTI, true));
1963
1964 MCSymbol* JTISymbol = GetJTISymbol(JTI);
1965 OutStreamer->emitLabel(JTISymbol);
1966
1967 for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
1968 emitJumpTableEntry(MJTI, JTBBs[ii], JTI);
1969 }
1970 if (!JTInDiffSection)
1971 OutStreamer->emitDataRegion(MCDR_DataRegionEnd);
1972 }
1973
1974 /// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the
1975 /// current stream.
emitJumpTableEntry(const MachineJumpTableInfo * MJTI,const MachineBasicBlock * MBB,unsigned UID) const1976 void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
1977 const MachineBasicBlock *MBB,
1978 unsigned UID) const {
1979 assert(MBB && MBB->getNumber() >= 0 && "Invalid basic block");
1980 const MCExpr *Value = nullptr;
1981 switch (MJTI->getEntryKind()) {
1982 case MachineJumpTableInfo::EK_Inline:
1983 llvm_unreachable("Cannot emit EK_Inline jump table entry");
1984 case MachineJumpTableInfo::EK_Custom32:
1985 Value = MF->getSubtarget().getTargetLowering()->LowerCustomJumpTableEntry(
1986 MJTI, MBB, UID, OutContext);
1987 break;
1988 case MachineJumpTableInfo::EK_BlockAddress:
1989 // EK_BlockAddress - Each entry is a plain address of block, e.g.:
1990 // .word LBB123
1991 Value = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
1992 break;
1993 case MachineJumpTableInfo::EK_GPRel32BlockAddress: {
1994 // EK_GPRel32BlockAddress - Each entry is an address of block, encoded
1995 // with a relocation as gp-relative, e.g.:
1996 // .gprel32 LBB123
1997 MCSymbol *MBBSym = MBB->getSymbol();
1998 OutStreamer->emitGPRel32Value(MCSymbolRefExpr::create(MBBSym, OutContext));
1999 return;
2000 }
2001
2002 case MachineJumpTableInfo::EK_GPRel64BlockAddress: {
2003 // EK_GPRel64BlockAddress - Each entry is an address of block, encoded
2004 // with a relocation as gp-relative, e.g.:
2005 // .gpdword LBB123
2006 MCSymbol *MBBSym = MBB->getSymbol();
2007 OutStreamer->emitGPRel64Value(MCSymbolRefExpr::create(MBBSym, OutContext));
2008 return;
2009 }
2010
2011 case MachineJumpTableInfo::EK_LabelDifference32: {
2012 // Each entry is the address of the block minus the address of the jump
2013 // table. This is used for PIC jump tables where gprel32 is not supported.
2014 // e.g.:
2015 // .word LBB123 - LJTI1_2
2016 // If the .set directive avoids relocations, this is emitted as:
2017 // .set L4_5_set_123, LBB123 - LJTI1_2
2018 // .word L4_5_set_123
2019 if (MAI->doesSetDirectiveSuppressReloc()) {
2020 Value = MCSymbolRefExpr::create(GetJTSetSymbol(UID, MBB->getNumber()),
2021 OutContext);
2022 break;
2023 }
2024 Value = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
2025 const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
2026 const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF, UID, OutContext);
2027 Value = MCBinaryExpr::createSub(Value, Base, OutContext);
2028 break;
2029 }
2030 }
2031
2032 assert(Value && "Unknown entry kind!");
2033
2034 unsigned EntrySize = MJTI->getEntrySize(getDataLayout());
2035 OutStreamer->emitValue(Value, EntrySize);
2036 }
2037
2038 /// EmitSpecialLLVMGlobal - Check to see if the specified global is a
2039 /// special global used by LLVM. If so, emit it and return true, otherwise
2040 /// do nothing and return false.
emitSpecialLLVMGlobal(const GlobalVariable * GV)2041 bool AsmPrinter::emitSpecialLLVMGlobal(const GlobalVariable *GV) {
2042 if (GV->getName() == "llvm.used") {
2043 if (MAI->hasNoDeadStrip()) // No need to emit this at all.
2044 emitLLVMUsedList(cast<ConstantArray>(GV->getInitializer()));
2045 return true;
2046 }
2047
2048 // Ignore debug and non-emitted data. This handles llvm.compiler.used.
2049 if (GV->getSection() == "llvm.metadata" ||
2050 GV->hasAvailableExternallyLinkage())
2051 return true;
2052
2053 if (!GV->hasAppendingLinkage()) return false;
2054
2055 assert(GV->hasInitializer() && "Not a special LLVM global!");
2056
2057 if (GV->getName() == "llvm.global_ctors") {
2058 emitXXStructorList(GV->getParent()->getDataLayout(), GV->getInitializer(),
2059 /* isCtor */ true);
2060
2061 return true;
2062 }
2063
2064 if (GV->getName() == "llvm.global_dtors") {
2065 emitXXStructorList(GV->getParent()->getDataLayout(), GV->getInitializer(),
2066 /* isCtor */ false);
2067
2068 return true;
2069 }
2070
2071 report_fatal_error("unknown special variable");
2072 }
2073
2074 /// EmitLLVMUsedList - For targets that define a MAI::UsedDirective, mark each
2075 /// global in the specified llvm.used list.
emitLLVMUsedList(const ConstantArray * InitList)2076 void AsmPrinter::emitLLVMUsedList(const ConstantArray *InitList) {
2077 // Should be an array of 'i8*'.
2078 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
2079 const GlobalValue *GV =
2080 dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
2081 if (GV)
2082 OutStreamer->emitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip);
2083 }
2084 }
2085
2086 namespace {
2087
2088 struct Structor {
2089 int Priority = 0;
2090 Constant *Func = nullptr;
2091 GlobalValue *ComdatKey = nullptr;
2092
2093 Structor() = default;
2094 };
2095
2096 } // end anonymous namespace
2097
2098 /// EmitXXStructorList - Emit the ctor or dtor list taking into account the init
2099 /// priority.
emitXXStructorList(const DataLayout & DL,const Constant * List,bool isCtor)2100 void AsmPrinter::emitXXStructorList(const DataLayout &DL, const Constant *List,
2101 bool isCtor) {
2102 // Should be an array of '{ i32, void ()*, i8* }' structs. The first value is the
2103 // init priority.
2104 if (!isa<ConstantArray>(List)) return;
2105
2106 // Gather the structors in a form that's convenient for sorting by priority.
2107 SmallVector<Structor, 8> Structors;
2108 for (Value *O : cast<ConstantArray>(List)->operands()) {
2109 auto *CS = cast<ConstantStruct>(O);
2110 if (CS->getOperand(1)->isNullValue())
2111 break; // Found a null terminator, skip the rest.
2112 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
2113 if (!Priority) continue; // Malformed.
2114 Structors.push_back(Structor());
2115 Structor &S = Structors.back();
2116 S.Priority = Priority->getLimitedValue(65535);
2117 S.Func = CS->getOperand(1);
2118 if (!CS->getOperand(2)->isNullValue())
2119 S.ComdatKey =
2120 dyn_cast<GlobalValue>(CS->getOperand(2)->stripPointerCasts());
2121 }
2122
2123 // Emit the function pointers in the target-specific order
2124 llvm::stable_sort(Structors, [](const Structor &L, const Structor &R) {
2125 return L.Priority < R.Priority;
2126 });
2127 const Align Align = DL.getPointerPrefAlignment();
2128 for (Structor &S : Structors) {
2129 const TargetLoweringObjectFile &Obj = getObjFileLowering();
2130 const MCSymbol *KeySym = nullptr;
2131 if (GlobalValue *GV = S.ComdatKey) {
2132 if (GV->isDeclarationForLinker())
2133 // If the associated variable is not defined in this module
2134 // (it might be available_externally, or have been an
2135 // available_externally definition that was dropped by the
2136 // EliminateAvailableExternally pass), some other TU
2137 // will provide its dynamic initializer.
2138 continue;
2139
2140 KeySym = getSymbol(GV);
2141 }
2142 MCSection *OutputSection =
2143 (isCtor ? Obj.getStaticCtorSection(S.Priority, KeySym)
2144 : Obj.getStaticDtorSection(S.Priority, KeySym));
2145 OutStreamer->SwitchSection(OutputSection);
2146 if (OutStreamer->getCurrentSection() != OutStreamer->getPreviousSection())
2147 emitAlignment(Align);
2148 emitXXStructor(DL, S.Func);
2149 }
2150 }
2151
emitModuleIdents(Module & M)2152 void AsmPrinter::emitModuleIdents(Module &M) {
2153 if (!MAI->hasIdentDirective())
2154 return;
2155
2156 if (const NamedMDNode *NMD = M.getNamedMetadata("llvm.ident")) {
2157 for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
2158 const MDNode *N = NMD->getOperand(i);
2159 assert(N->getNumOperands() == 1 &&
2160 "llvm.ident metadata entry can have only one operand");
2161 const MDString *S = cast<MDString>(N->getOperand(0));
2162 OutStreamer->emitIdent(S->getString());
2163 }
2164 }
2165 }
2166
emitModuleCommandLines(Module & M)2167 void AsmPrinter::emitModuleCommandLines(Module &M) {
2168 MCSection *CommandLine = getObjFileLowering().getSectionForCommandLines();
2169 if (!CommandLine)
2170 return;
2171
2172 const NamedMDNode *NMD = M.getNamedMetadata("llvm.commandline");
2173 if (!NMD || !NMD->getNumOperands())
2174 return;
2175
2176 OutStreamer->PushSection();
2177 OutStreamer->SwitchSection(CommandLine);
2178 OutStreamer->emitZeros(1);
2179 for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
2180 const MDNode *N = NMD->getOperand(i);
2181 assert(N->getNumOperands() == 1 &&
2182 "llvm.commandline metadata entry can have only one operand");
2183 const MDString *S = cast<MDString>(N->getOperand(0));
2184 OutStreamer->emitBytes(S->getString());
2185 OutStreamer->emitZeros(1);
2186 }
2187 OutStreamer->PopSection();
2188 }
2189
2190 //===--------------------------------------------------------------------===//
2191 // Emission and print routines
2192 //
2193
2194 /// Emit a byte directive and value.
2195 ///
emitInt8(int Value) const2196 void AsmPrinter::emitInt8(int Value) const { OutStreamer->emitInt8(Value); }
2197
2198 /// Emit a short directive and value.
emitInt16(int Value) const2199 void AsmPrinter::emitInt16(int Value) const { OutStreamer->emitInt16(Value); }
2200
2201 /// Emit a long directive and value.
emitInt32(int Value) const2202 void AsmPrinter::emitInt32(int Value) const { OutStreamer->emitInt32(Value); }
2203
2204 /// Emit a long long directive and value.
emitInt64(uint64_t Value) const2205 void AsmPrinter::emitInt64(uint64_t Value) const {
2206 OutStreamer->emitInt64(Value);
2207 }
2208
2209 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
2210 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses
2211 /// .set if it avoids relocations.
emitLabelDifference(const MCSymbol * Hi,const MCSymbol * Lo,unsigned Size) const2212 void AsmPrinter::emitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
2213 unsigned Size) const {
2214 OutStreamer->emitAbsoluteSymbolDiff(Hi, Lo, Size);
2215 }
2216
2217 /// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
2218 /// where the size in bytes of the directive is specified by Size and Label
2219 /// specifies the label. This implicitly uses .set if it is available.
emitLabelPlusOffset(const MCSymbol * Label,uint64_t Offset,unsigned Size,bool IsSectionRelative) const2220 void AsmPrinter::emitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
2221 unsigned Size,
2222 bool IsSectionRelative) const {
2223 if (MAI->needsDwarfSectionOffsetDirective() && IsSectionRelative) {
2224 OutStreamer->EmitCOFFSecRel32(Label, Offset);
2225 if (Size > 4)
2226 OutStreamer->emitZeros(Size - 4);
2227 return;
2228 }
2229
2230 // Emit Label+Offset (or just Label if Offset is zero)
2231 const MCExpr *Expr = MCSymbolRefExpr::create(Label, OutContext);
2232 if (Offset)
2233 Expr = MCBinaryExpr::createAdd(
2234 Expr, MCConstantExpr::create(Offset, OutContext), OutContext);
2235
2236 OutStreamer->emitValue(Expr, Size);
2237 }
2238
2239 //===----------------------------------------------------------------------===//
2240
2241 // EmitAlignment - Emit an alignment directive to the specified power of
2242 // two boundary. If a global value is specified, and if that global has
2243 // an explicit alignment requested, it will override the alignment request
2244 // if required for correctness.
emitAlignment(Align Alignment,const GlobalObject * GV) const2245 void AsmPrinter::emitAlignment(Align Alignment, const GlobalObject *GV) const {
2246 if (GV)
2247 Alignment = getGVAlignment(GV, GV->getParent()->getDataLayout(), Alignment);
2248
2249 if (Alignment == Align(1))
2250 return; // 1-byte aligned: no need to emit alignment.
2251
2252 if (getCurrentSection()->getKind().isText())
2253 OutStreamer->emitCodeAlignment(Alignment.value());
2254 else
2255 OutStreamer->emitValueToAlignment(Alignment.value());
2256 }
2257
2258 //===----------------------------------------------------------------------===//
2259 // Constant emission.
2260 //===----------------------------------------------------------------------===//
2261
lowerConstant(const Constant * CV)2262 const MCExpr *AsmPrinter::lowerConstant(const Constant *CV) {
2263 MCContext &Ctx = OutContext;
2264
2265 if (CV->isNullValue() || isa<UndefValue>(CV))
2266 return MCConstantExpr::create(0, Ctx);
2267
2268 if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV))
2269 return MCConstantExpr::create(CI->getZExtValue(), Ctx);
2270
2271 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
2272 return MCSymbolRefExpr::create(getSymbol(GV), Ctx);
2273
2274 if (const BlockAddress *BA = dyn_cast<BlockAddress>(CV))
2275 return MCSymbolRefExpr::create(GetBlockAddressSymbol(BA), Ctx);
2276
2277 const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
2278 if (!CE) {
2279 llvm_unreachable("Unknown constant value to lower!");
2280 }
2281
2282 switch (CE->getOpcode()) {
2283 default: {
2284 // If the code isn't optimized, there may be outstanding folding
2285 // opportunities. Attempt to fold the expression using DataLayout as a
2286 // last resort before giving up.
2287 Constant *C = ConstantFoldConstant(CE, getDataLayout());
2288 if (C != CE)
2289 return lowerConstant(C);
2290
2291 // Otherwise report the problem to the user.
2292 std::string S;
2293 raw_string_ostream OS(S);
2294 OS << "Unsupported expression in static initializer: ";
2295 CE->printAsOperand(OS, /*PrintType=*/false,
2296 !MF ? nullptr : MF->getFunction().getParent());
2297 report_fatal_error(OS.str());
2298 }
2299 case Instruction::GetElementPtr: {
2300 // Generate a symbolic expression for the byte address
2301 APInt OffsetAI(getDataLayout().getPointerTypeSizeInBits(CE->getType()), 0);
2302 cast<GEPOperator>(CE)->accumulateConstantOffset(getDataLayout(), OffsetAI);
2303
2304 const MCExpr *Base = lowerConstant(CE->getOperand(0));
2305 if (!OffsetAI)
2306 return Base;
2307
2308 int64_t Offset = OffsetAI.getSExtValue();
2309 return MCBinaryExpr::createAdd(Base, MCConstantExpr::create(Offset, Ctx),
2310 Ctx);
2311 }
2312
2313 case Instruction::Trunc:
2314 // We emit the value and depend on the assembler to truncate the generated
2315 // expression properly. This is important for differences between
2316 // blockaddress labels. Since the two labels are in the same function, it
2317 // is reasonable to treat their delta as a 32-bit value.
2318 LLVM_FALLTHROUGH;
2319 case Instruction::BitCast:
2320 return lowerConstant(CE->getOperand(0));
2321
2322 case Instruction::IntToPtr: {
2323 const DataLayout &DL = getDataLayout();
2324
2325 // Handle casts to pointers by changing them into casts to the appropriate
2326 // integer type. This promotes constant folding and simplifies this code.
2327 Constant *Op = CE->getOperand(0);
2328 Op = ConstantExpr::getIntegerCast(Op, DL.getIntPtrType(CV->getType()),
2329 false/*ZExt*/);
2330 return lowerConstant(Op);
2331 }
2332
2333 case Instruction::PtrToInt: {
2334 const DataLayout &DL = getDataLayout();
2335
2336 // Support only foldable casts to/from pointers that can be eliminated by
2337 // changing the pointer to the appropriately sized integer type.
2338 Constant *Op = CE->getOperand(0);
2339 Type *Ty = CE->getType();
2340
2341 const MCExpr *OpExpr = lowerConstant(Op);
2342
2343 // We can emit the pointer value into this slot if the slot is an
2344 // integer slot equal to the size of the pointer.
2345 //
2346 // If the pointer is larger than the resultant integer, then
2347 // as with Trunc just depend on the assembler to truncate it.
2348 if (DL.getTypeAllocSize(Ty) <= DL.getTypeAllocSize(Op->getType()))
2349 return OpExpr;
2350
2351 // Otherwise the pointer is smaller than the resultant integer, mask off
2352 // the high bits so we are sure to get a proper truncation if the input is
2353 // a constant expr.
2354 unsigned InBits = DL.getTypeAllocSizeInBits(Op->getType());
2355 const MCExpr *MaskExpr = MCConstantExpr::create(~0ULL >> (64-InBits), Ctx);
2356 return MCBinaryExpr::createAnd(OpExpr, MaskExpr, Ctx);
2357 }
2358
2359 case Instruction::Sub: {
2360 GlobalValue *LHSGV;
2361 APInt LHSOffset;
2362 if (IsConstantOffsetFromGlobal(CE->getOperand(0), LHSGV, LHSOffset,
2363 getDataLayout())) {
2364 GlobalValue *RHSGV;
2365 APInt RHSOffset;
2366 if (IsConstantOffsetFromGlobal(CE->getOperand(1), RHSGV, RHSOffset,
2367 getDataLayout())) {
2368 const MCExpr *RelocExpr =
2369 getObjFileLowering().lowerRelativeReference(LHSGV, RHSGV, TM);
2370 if (!RelocExpr)
2371 RelocExpr = MCBinaryExpr::createSub(
2372 MCSymbolRefExpr::create(getSymbol(LHSGV), Ctx),
2373 MCSymbolRefExpr::create(getSymbol(RHSGV), Ctx), Ctx);
2374 int64_t Addend = (LHSOffset - RHSOffset).getSExtValue();
2375 if (Addend != 0)
2376 RelocExpr = MCBinaryExpr::createAdd(
2377 RelocExpr, MCConstantExpr::create(Addend, Ctx), Ctx);
2378 return RelocExpr;
2379 }
2380 }
2381 }
2382 // else fallthrough
2383 LLVM_FALLTHROUGH;
2384
2385 // The MC library also has a right-shift operator, but it isn't consistently
2386 // signed or unsigned between different targets.
2387 case Instruction::Add:
2388 case Instruction::Mul:
2389 case Instruction::SDiv:
2390 case Instruction::SRem:
2391 case Instruction::Shl:
2392 case Instruction::And:
2393 case Instruction::Or:
2394 case Instruction::Xor: {
2395 const MCExpr *LHS = lowerConstant(CE->getOperand(0));
2396 const MCExpr *RHS = lowerConstant(CE->getOperand(1));
2397 switch (CE->getOpcode()) {
2398 default: llvm_unreachable("Unknown binary operator constant cast expr");
2399 case Instruction::Add: return MCBinaryExpr::createAdd(LHS, RHS, Ctx);
2400 case Instruction::Sub: return MCBinaryExpr::createSub(LHS, RHS, Ctx);
2401 case Instruction::Mul: return MCBinaryExpr::createMul(LHS, RHS, Ctx);
2402 case Instruction::SDiv: return MCBinaryExpr::createDiv(LHS, RHS, Ctx);
2403 case Instruction::SRem: return MCBinaryExpr::createMod(LHS, RHS, Ctx);
2404 case Instruction::Shl: return MCBinaryExpr::createShl(LHS, RHS, Ctx);
2405 case Instruction::And: return MCBinaryExpr::createAnd(LHS, RHS, Ctx);
2406 case Instruction::Or: return MCBinaryExpr::createOr (LHS, RHS, Ctx);
2407 case Instruction::Xor: return MCBinaryExpr::createXor(LHS, RHS, Ctx);
2408 }
2409 }
2410 }
2411 }
2412
2413 static void emitGlobalConstantImpl(const DataLayout &DL, const Constant *C,
2414 AsmPrinter &AP,
2415 const Constant *BaseCV = nullptr,
2416 uint64_t Offset = 0);
2417
2418 static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP);
2419 static void emitGlobalConstantFP(APFloat APF, Type *ET, AsmPrinter &AP);
2420
2421 /// isRepeatedByteSequence - Determine whether the given value is
2422 /// composed of a repeated sequence of identical bytes and return the
2423 /// byte value. If it is not a repeated sequence, return -1.
isRepeatedByteSequence(const ConstantDataSequential * V)2424 static int isRepeatedByteSequence(const ConstantDataSequential *V) {
2425 StringRef Data = V->getRawDataValues();
2426 assert(!Data.empty() && "Empty aggregates should be CAZ node");
2427 char C = Data[0];
2428 for (unsigned i = 1, e = Data.size(); i != e; ++i)
2429 if (Data[i] != C) return -1;
2430 return static_cast<uint8_t>(C); // Ensure 255 is not returned as -1.
2431 }
2432
2433 /// isRepeatedByteSequence - Determine whether the given value is
2434 /// composed of a repeated sequence of identical bytes and return the
2435 /// byte value. If it is not a repeated sequence, return -1.
isRepeatedByteSequence(const Value * V,const DataLayout & DL)2436 static int isRepeatedByteSequence(const Value *V, const DataLayout &DL) {
2437 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
2438 uint64_t Size = DL.getTypeAllocSizeInBits(V->getType());
2439 assert(Size % 8 == 0);
2440
2441 // Extend the element to take zero padding into account.
2442 APInt Value = CI->getValue().zextOrSelf(Size);
2443 if (!Value.isSplat(8))
2444 return -1;
2445
2446 return Value.zextOrTrunc(8).getZExtValue();
2447 }
2448 if (const ConstantArray *CA = dyn_cast<ConstantArray>(V)) {
2449 // Make sure all array elements are sequences of the same repeated
2450 // byte.
2451 assert(CA->getNumOperands() != 0 && "Should be a CAZ");
2452 Constant *Op0 = CA->getOperand(0);
2453 int Byte = isRepeatedByteSequence(Op0, DL);
2454 if (Byte == -1)
2455 return -1;
2456
2457 // All array elements must be equal.
2458 for (unsigned i = 1, e = CA->getNumOperands(); i != e; ++i)
2459 if (CA->getOperand(i) != Op0)
2460 return -1;
2461 return Byte;
2462 }
2463
2464 if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(V))
2465 return isRepeatedByteSequence(CDS);
2466
2467 return -1;
2468 }
2469
emitGlobalConstantDataSequential(const DataLayout & DL,const ConstantDataSequential * CDS,AsmPrinter & AP)2470 static void emitGlobalConstantDataSequential(const DataLayout &DL,
2471 const ConstantDataSequential *CDS,
2472 AsmPrinter &AP) {
2473 // See if we can aggregate this into a .fill, if so, emit it as such.
2474 int Value = isRepeatedByteSequence(CDS, DL);
2475 if (Value != -1) {
2476 uint64_t Bytes = DL.getTypeAllocSize(CDS->getType());
2477 // Don't emit a 1-byte object as a .fill.
2478 if (Bytes > 1)
2479 return AP.OutStreamer->emitFill(Bytes, Value);
2480 }
2481
2482 // If this can be emitted with .ascii/.asciz, emit it as such.
2483 if (CDS->isString())
2484 return AP.OutStreamer->emitBytes(CDS->getAsString());
2485
2486 // Otherwise, emit the values in successive locations.
2487 unsigned ElementByteSize = CDS->getElementByteSize();
2488 if (isa<IntegerType>(CDS->getElementType())) {
2489 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
2490 if (AP.isVerbose())
2491 AP.OutStreamer->GetCommentOS() << format("0x%" PRIx64 "\n",
2492 CDS->getElementAsInteger(i));
2493 AP.OutStreamer->emitIntValue(CDS->getElementAsInteger(i),
2494 ElementByteSize);
2495 }
2496 } else {
2497 Type *ET = CDS->getElementType();
2498 for (unsigned I = 0, E = CDS->getNumElements(); I != E; ++I)
2499 emitGlobalConstantFP(CDS->getElementAsAPFloat(I), ET, AP);
2500 }
2501
2502 unsigned Size = DL.getTypeAllocSize(CDS->getType());
2503 unsigned EmittedSize =
2504 DL.getTypeAllocSize(CDS->getElementType()) * CDS->getNumElements();
2505 assert(EmittedSize <= Size && "Size cannot be less than EmittedSize!");
2506 if (unsigned Padding = Size - EmittedSize)
2507 AP.OutStreamer->emitZeros(Padding);
2508 }
2509
emitGlobalConstantArray(const DataLayout & DL,const ConstantArray * CA,AsmPrinter & AP,const Constant * BaseCV,uint64_t Offset)2510 static void emitGlobalConstantArray(const DataLayout &DL,
2511 const ConstantArray *CA, AsmPrinter &AP,
2512 const Constant *BaseCV, uint64_t Offset) {
2513 // See if we can aggregate some values. Make sure it can be
2514 // represented as a series of bytes of the constant value.
2515 int Value = isRepeatedByteSequence(CA, DL);
2516
2517 if (Value != -1) {
2518 uint64_t Bytes = DL.getTypeAllocSize(CA->getType());
2519 AP.OutStreamer->emitFill(Bytes, Value);
2520 }
2521 else {
2522 for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
2523 emitGlobalConstantImpl(DL, CA->getOperand(i), AP, BaseCV, Offset);
2524 Offset += DL.getTypeAllocSize(CA->getOperand(i)->getType());
2525 }
2526 }
2527 }
2528
emitGlobalConstantVector(const DataLayout & DL,const ConstantVector * CV,AsmPrinter & AP)2529 static void emitGlobalConstantVector(const DataLayout &DL,
2530 const ConstantVector *CV, AsmPrinter &AP) {
2531 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
2532 emitGlobalConstantImpl(DL, CV->getOperand(i), AP);
2533
2534 unsigned Size = DL.getTypeAllocSize(CV->getType());
2535 unsigned EmittedSize = DL.getTypeAllocSize(CV->getType()->getElementType()) *
2536 CV->getType()->getNumElements();
2537 if (unsigned Padding = Size - EmittedSize)
2538 AP.OutStreamer->emitZeros(Padding);
2539 }
2540
emitGlobalConstantStruct(const DataLayout & DL,const ConstantStruct * CS,AsmPrinter & AP,const Constant * BaseCV,uint64_t Offset)2541 static void emitGlobalConstantStruct(const DataLayout &DL,
2542 const ConstantStruct *CS, AsmPrinter &AP,
2543 const Constant *BaseCV, uint64_t Offset) {
2544 // Print the fields in successive locations. Pad to align if needed!
2545 unsigned Size = DL.getTypeAllocSize(CS->getType());
2546 const StructLayout *Layout = DL.getStructLayout(CS->getType());
2547 uint64_t SizeSoFar = 0;
2548 for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
2549 const Constant *Field = CS->getOperand(i);
2550
2551 // Print the actual field value.
2552 emitGlobalConstantImpl(DL, Field, AP, BaseCV, Offset + SizeSoFar);
2553
2554 // Check if padding is needed and insert one or more 0s.
2555 uint64_t FieldSize = DL.getTypeAllocSize(Field->getType());
2556 uint64_t PadSize = ((i == e-1 ? Size : Layout->getElementOffset(i+1))
2557 - Layout->getElementOffset(i)) - FieldSize;
2558 SizeSoFar += FieldSize + PadSize;
2559
2560 // Insert padding - this may include padding to increase the size of the
2561 // current field up to the ABI size (if the struct is not packed) as well
2562 // as padding to ensure that the next field starts at the right offset.
2563 AP.OutStreamer->emitZeros(PadSize);
2564 }
2565 assert(SizeSoFar == Layout->getSizeInBytes() &&
2566 "Layout of constant struct may be incorrect!");
2567 }
2568
emitGlobalConstantFP(APFloat APF,Type * ET,AsmPrinter & AP)2569 static void emitGlobalConstantFP(APFloat APF, Type *ET, AsmPrinter &AP) {
2570 assert(ET && "Unknown float type");
2571 APInt API = APF.bitcastToAPInt();
2572
2573 // First print a comment with what we think the original floating-point value
2574 // should have been.
2575 if (AP.isVerbose()) {
2576 SmallString<8> StrVal;
2577 APF.toString(StrVal);
2578 ET->print(AP.OutStreamer->GetCommentOS());
2579 AP.OutStreamer->GetCommentOS() << ' ' << StrVal << '\n';
2580 }
2581
2582 // Now iterate through the APInt chunks, emitting them in endian-correct
2583 // order, possibly with a smaller chunk at beginning/end (e.g. for x87 80-bit
2584 // floats).
2585 unsigned NumBytes = API.getBitWidth() / 8;
2586 unsigned TrailingBytes = NumBytes % sizeof(uint64_t);
2587 const uint64_t *p = API.getRawData();
2588
2589 // PPC's long double has odd notions of endianness compared to how LLVM
2590 // handles it: p[0] goes first for *big* endian on PPC.
2591 if (AP.getDataLayout().isBigEndian() && !ET->isPPC_FP128Ty()) {
2592 int Chunk = API.getNumWords() - 1;
2593
2594 if (TrailingBytes)
2595 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk--], TrailingBytes);
2596
2597 for (; Chunk >= 0; --Chunk)
2598 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], sizeof(uint64_t));
2599 } else {
2600 unsigned Chunk;
2601 for (Chunk = 0; Chunk < NumBytes / sizeof(uint64_t); ++Chunk)
2602 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], sizeof(uint64_t));
2603
2604 if (TrailingBytes)
2605 AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], TrailingBytes);
2606 }
2607
2608 // Emit the tail padding for the long double.
2609 const DataLayout &DL = AP.getDataLayout();
2610 AP.OutStreamer->emitZeros(DL.getTypeAllocSize(ET) - DL.getTypeStoreSize(ET));
2611 }
2612
emitGlobalConstantFP(const ConstantFP * CFP,AsmPrinter & AP)2613 static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP) {
2614 emitGlobalConstantFP(CFP->getValueAPF(), CFP->getType(), AP);
2615 }
2616
emitGlobalConstantLargeInt(const ConstantInt * CI,AsmPrinter & AP)2617 static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP) {
2618 const DataLayout &DL = AP.getDataLayout();
2619 unsigned BitWidth = CI->getBitWidth();
2620
2621 // Copy the value as we may massage the layout for constants whose bit width
2622 // is not a multiple of 64-bits.
2623 APInt Realigned(CI->getValue());
2624 uint64_t ExtraBits = 0;
2625 unsigned ExtraBitsSize = BitWidth & 63;
2626
2627 if (ExtraBitsSize) {
2628 // The bit width of the data is not a multiple of 64-bits.
2629 // The extra bits are expected to be at the end of the chunk of the memory.
2630 // Little endian:
2631 // * Nothing to be done, just record the extra bits to emit.
2632 // Big endian:
2633 // * Record the extra bits to emit.
2634 // * Realign the raw data to emit the chunks of 64-bits.
2635 if (DL.isBigEndian()) {
2636 // Basically the structure of the raw data is a chunk of 64-bits cells:
2637 // 0 1 BitWidth / 64
2638 // [chunk1][chunk2] ... [chunkN].
2639 // The most significant chunk is chunkN and it should be emitted first.
2640 // However, due to the alignment issue chunkN contains useless bits.
2641 // Realign the chunks so that they contain only useful information:
2642 // ExtraBits 0 1 (BitWidth / 64) - 1
2643 // chu[nk1 chu][nk2 chu] ... [nkN-1 chunkN]
2644 ExtraBitsSize = alignTo(ExtraBitsSize, 8);
2645 ExtraBits = Realigned.getRawData()[0] &
2646 (((uint64_t)-1) >> (64 - ExtraBitsSize));
2647 Realigned.lshrInPlace(ExtraBitsSize);
2648 } else
2649 ExtraBits = Realigned.getRawData()[BitWidth / 64];
2650 }
2651
2652 // We don't expect assemblers to support integer data directives
2653 // for more than 64 bits, so we emit the data in at most 64-bit
2654 // quantities at a time.
2655 const uint64_t *RawData = Realigned.getRawData();
2656 for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
2657 uint64_t Val = DL.isBigEndian() ? RawData[e - i - 1] : RawData[i];
2658 AP.OutStreamer->emitIntValue(Val, 8);
2659 }
2660
2661 if (ExtraBitsSize) {
2662 // Emit the extra bits after the 64-bits chunks.
2663
2664 // Emit a directive that fills the expected size.
2665 uint64_t Size = AP.getDataLayout().getTypeStoreSize(CI->getType());
2666 Size -= (BitWidth / 64) * 8;
2667 assert(Size && Size * 8 >= ExtraBitsSize &&
2668 (ExtraBits & (((uint64_t)-1) >> (64 - ExtraBitsSize)))
2669 == ExtraBits && "Directive too small for extra bits.");
2670 AP.OutStreamer->emitIntValue(ExtraBits, Size);
2671 }
2672 }
2673
2674 /// Transform a not absolute MCExpr containing a reference to a GOT
2675 /// equivalent global, by a target specific GOT pc relative access to the
2676 /// final symbol.
handleIndirectSymViaGOTPCRel(AsmPrinter & AP,const MCExpr ** ME,const Constant * BaseCst,uint64_t Offset)2677 static void handleIndirectSymViaGOTPCRel(AsmPrinter &AP, const MCExpr **ME,
2678 const Constant *BaseCst,
2679 uint64_t Offset) {
2680 // The global @foo below illustrates a global that uses a got equivalent.
2681 //
2682 // @bar = global i32 42
2683 // @gotequiv = private unnamed_addr constant i32* @bar
2684 // @foo = i32 trunc (i64 sub (i64 ptrtoint (i32** @gotequiv to i64),
2685 // i64 ptrtoint (i32* @foo to i64))
2686 // to i32)
2687 //
2688 // The cstexpr in @foo is converted into the MCExpr `ME`, where we actually
2689 // check whether @foo is suitable to use a GOTPCREL. `ME` is usually in the
2690 // form:
2691 //
2692 // foo = cstexpr, where
2693 // cstexpr := <gotequiv> - "." + <cst>
2694 // cstexpr := <gotequiv> - (<foo> - <offset from @foo base>) + <cst>
2695 //
2696 // After canonicalization by evaluateAsRelocatable `ME` turns into:
2697 //
2698 // cstexpr := <gotequiv> - <foo> + gotpcrelcst, where
2699 // gotpcrelcst := <offset from @foo base> + <cst>
2700 MCValue MV;
2701 if (!(*ME)->evaluateAsRelocatable(MV, nullptr, nullptr) || MV.isAbsolute())
2702 return;
2703 const MCSymbolRefExpr *SymA = MV.getSymA();
2704 if (!SymA)
2705 return;
2706
2707 // Check that GOT equivalent symbol is cached.
2708 const MCSymbol *GOTEquivSym = &SymA->getSymbol();
2709 if (!AP.GlobalGOTEquivs.count(GOTEquivSym))
2710 return;
2711
2712 const GlobalValue *BaseGV = dyn_cast_or_null<GlobalValue>(BaseCst);
2713 if (!BaseGV)
2714 return;
2715
2716 // Check for a valid base symbol
2717 const MCSymbol *BaseSym = AP.getSymbol(BaseGV);
2718 const MCSymbolRefExpr *SymB = MV.getSymB();
2719
2720 if (!SymB || BaseSym != &SymB->getSymbol())
2721 return;
2722
2723 // Make sure to match:
2724 //
2725 // gotpcrelcst := <offset from @foo base> + <cst>
2726 //
2727 // If gotpcrelcst is positive it means that we can safely fold the pc rel
2728 // displacement into the GOTPCREL. We can also can have an extra offset <cst>
2729 // if the target knows how to encode it.
2730 int64_t GOTPCRelCst = Offset + MV.getConstant();
2731 if (GOTPCRelCst < 0)
2732 return;
2733 if (!AP.getObjFileLowering().supportGOTPCRelWithOffset() && GOTPCRelCst != 0)
2734 return;
2735
2736 // Emit the GOT PC relative to replace the got equivalent global, i.e.:
2737 //
2738 // bar:
2739 // .long 42
2740 // gotequiv:
2741 // .quad bar
2742 // foo:
2743 // .long gotequiv - "." + <cst>
2744 //
2745 // is replaced by the target specific equivalent to:
2746 //
2747 // bar:
2748 // .long 42
2749 // foo:
2750 // .long bar@GOTPCREL+<gotpcrelcst>
2751 AsmPrinter::GOTEquivUsePair Result = AP.GlobalGOTEquivs[GOTEquivSym];
2752 const GlobalVariable *GV = Result.first;
2753 int NumUses = (int)Result.second;
2754 const GlobalValue *FinalGV = dyn_cast<GlobalValue>(GV->getOperand(0));
2755 const MCSymbol *FinalSym = AP.getSymbol(FinalGV);
2756 *ME = AP.getObjFileLowering().getIndirectSymViaGOTPCRel(
2757 FinalGV, FinalSym, MV, Offset, AP.MMI, *AP.OutStreamer);
2758
2759 // Update GOT equivalent usage information
2760 --NumUses;
2761 if (NumUses >= 0)
2762 AP.GlobalGOTEquivs[GOTEquivSym] = std::make_pair(GV, NumUses);
2763 }
2764
emitGlobalConstantImpl(const DataLayout & DL,const Constant * CV,AsmPrinter & AP,const Constant * BaseCV,uint64_t Offset)2765 static void emitGlobalConstantImpl(const DataLayout &DL, const Constant *CV,
2766 AsmPrinter &AP, const Constant *BaseCV,
2767 uint64_t Offset) {
2768 uint64_t Size = DL.getTypeAllocSize(CV->getType());
2769
2770 // Globals with sub-elements such as combinations of arrays and structs
2771 // are handled recursively by emitGlobalConstantImpl. Keep track of the
2772 // constant symbol base and the current position with BaseCV and Offset.
2773 if (!BaseCV && CV->hasOneUse())
2774 BaseCV = dyn_cast<Constant>(CV->user_back());
2775
2776 if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
2777 return AP.OutStreamer->emitZeros(Size);
2778
2779 if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
2780 const uint64_t StoreSize = DL.getTypeStoreSize(CV->getType());
2781
2782 if (StoreSize <= 8) {
2783 if (AP.isVerbose())
2784 AP.OutStreamer->GetCommentOS() << format("0x%" PRIx64 "\n",
2785 CI->getZExtValue());
2786 AP.OutStreamer->emitIntValue(CI->getZExtValue(), StoreSize);
2787 } else {
2788 emitGlobalConstantLargeInt(CI, AP);
2789 }
2790
2791 // Emit tail padding if needed
2792 if (Size != StoreSize)
2793 AP.OutStreamer->emitZeros(Size - StoreSize);
2794
2795 return;
2796 }
2797
2798 if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV))
2799 return emitGlobalConstantFP(CFP, AP);
2800
2801 if (isa<ConstantPointerNull>(CV)) {
2802 AP.OutStreamer->emitIntValue(0, Size);
2803 return;
2804 }
2805
2806 if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(CV))
2807 return emitGlobalConstantDataSequential(DL, CDS, AP);
2808
2809 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV))
2810 return emitGlobalConstantArray(DL, CVA, AP, BaseCV, Offset);
2811
2812 if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
2813 return emitGlobalConstantStruct(DL, CVS, AP, BaseCV, Offset);
2814
2815 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
2816 // Look through bitcasts, which might not be able to be MCExpr'ized (e.g. of
2817 // vectors).
2818 if (CE->getOpcode() == Instruction::BitCast)
2819 return emitGlobalConstantImpl(DL, CE->getOperand(0), AP);
2820
2821 if (Size > 8) {
2822 // If the constant expression's size is greater than 64-bits, then we have
2823 // to emit the value in chunks. Try to constant fold the value and emit it
2824 // that way.
2825 Constant *New = ConstantFoldConstant(CE, DL);
2826 if (New != CE)
2827 return emitGlobalConstantImpl(DL, New, AP);
2828 }
2829 }
2830
2831 if (const ConstantVector *V = dyn_cast<ConstantVector>(CV))
2832 return emitGlobalConstantVector(DL, V, AP);
2833
2834 // Otherwise, it must be a ConstantExpr. Lower it to an MCExpr, then emit it
2835 // thread the streamer with EmitValue.
2836 const MCExpr *ME = AP.lowerConstant(CV);
2837
2838 // Since lowerConstant already folded and got rid of all IR pointer and
2839 // integer casts, detect GOT equivalent accesses by looking into the MCExpr
2840 // directly.
2841 if (AP.getObjFileLowering().supportIndirectSymViaGOTPCRel())
2842 handleIndirectSymViaGOTPCRel(AP, &ME, BaseCV, Offset);
2843
2844 AP.OutStreamer->emitValue(ME, Size);
2845 }
2846
2847 /// EmitGlobalConstant - Print a general LLVM constant to the .s file.
emitGlobalConstant(const DataLayout & DL,const Constant * CV)2848 void AsmPrinter::emitGlobalConstant(const DataLayout &DL, const Constant *CV) {
2849 uint64_t Size = DL.getTypeAllocSize(CV->getType());
2850 if (Size)
2851 emitGlobalConstantImpl(DL, CV, *this);
2852 else if (MAI->hasSubsectionsViaSymbols()) {
2853 // If the global has zero size, emit a single byte so that two labels don't
2854 // look like they are at the same location.
2855 OutStreamer->emitIntValue(0, 1);
2856 }
2857 }
2858
emitMachineConstantPoolValue(MachineConstantPoolValue * MCPV)2859 void AsmPrinter::emitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) {
2860 // Target doesn't support this yet!
2861 llvm_unreachable("Target does not support EmitMachineConstantPoolValue");
2862 }
2863
printOffset(int64_t Offset,raw_ostream & OS) const2864 void AsmPrinter::printOffset(int64_t Offset, raw_ostream &OS) const {
2865 if (Offset > 0)
2866 OS << '+' << Offset;
2867 else if (Offset < 0)
2868 OS << Offset;
2869 }
2870
emitNops(unsigned N)2871 void AsmPrinter::emitNops(unsigned N) {
2872 MCInst Nop;
2873 MF->getSubtarget().getInstrInfo()->getNoop(Nop);
2874 for (; N; --N)
2875 EmitToStreamer(*OutStreamer, Nop);
2876 }
2877
2878 //===----------------------------------------------------------------------===//
2879 // Symbol Lowering Routines.
2880 //===----------------------------------------------------------------------===//
2881
createTempSymbol(const Twine & Name) const2882 MCSymbol *AsmPrinter::createTempSymbol(const Twine &Name) const {
2883 return OutContext.createTempSymbol(Name, true);
2884 }
2885
GetBlockAddressSymbol(const BlockAddress * BA) const2886 MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BlockAddress *BA) const {
2887 return MMI->getAddrLabelSymbol(BA->getBasicBlock());
2888 }
2889
GetBlockAddressSymbol(const BasicBlock * BB) const2890 MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BasicBlock *BB) const {
2891 return MMI->getAddrLabelSymbol(BB);
2892 }
2893
2894 /// GetCPISymbol - Return the symbol for the specified constant pool entry.
GetCPISymbol(unsigned CPID) const2895 MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
2896 if (getSubtargetInfo().getTargetTriple().isWindowsMSVCEnvironment()) {
2897 const MachineConstantPoolEntry &CPE =
2898 MF->getConstantPool()->getConstants()[CPID];
2899 if (!CPE.isMachineConstantPoolEntry()) {
2900 const DataLayout &DL = MF->getDataLayout();
2901 SectionKind Kind = CPE.getSectionKind(&DL);
2902 const Constant *C = CPE.Val.ConstVal;
2903 Align Alignment = CPE.Alignment;
2904 if (const MCSectionCOFF *S = dyn_cast<MCSectionCOFF>(
2905 getObjFileLowering().getSectionForConstant(DL, Kind, C,
2906 Alignment))) {
2907 if (MCSymbol *Sym = S->getCOMDATSymbol()) {
2908 if (Sym->isUndefined())
2909 OutStreamer->emitSymbolAttribute(Sym, MCSA_Global);
2910 return Sym;
2911 }
2912 }
2913 }
2914 }
2915
2916 const DataLayout &DL = getDataLayout();
2917 return OutContext.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
2918 "CPI" + Twine(getFunctionNumber()) + "_" +
2919 Twine(CPID));
2920 }
2921
2922 /// GetJTISymbol - Return the symbol for the specified jump table entry.
GetJTISymbol(unsigned JTID,bool isLinkerPrivate) const2923 MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool isLinkerPrivate) const {
2924 return MF->getJTISymbol(JTID, OutContext, isLinkerPrivate);
2925 }
2926
2927 /// GetJTSetSymbol - Return the symbol for the specified jump table .set
2928 /// FIXME: privatize to AsmPrinter.
GetJTSetSymbol(unsigned UID,unsigned MBBID) const2929 MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
2930 const DataLayout &DL = getDataLayout();
2931 return OutContext.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
2932 Twine(getFunctionNumber()) + "_" +
2933 Twine(UID) + "_set_" + Twine(MBBID));
2934 }
2935
getSymbolWithGlobalValueBase(const GlobalValue * GV,StringRef Suffix) const2936 MCSymbol *AsmPrinter::getSymbolWithGlobalValueBase(const GlobalValue *GV,
2937 StringRef Suffix) const {
2938 return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, TM);
2939 }
2940
2941 /// Return the MCSymbol for the specified ExternalSymbol.
GetExternalSymbolSymbol(StringRef Sym) const2942 MCSymbol *AsmPrinter::GetExternalSymbolSymbol(StringRef Sym) const {
2943 SmallString<60> NameStr;
2944 Mangler::getNameWithPrefix(NameStr, Sym, getDataLayout());
2945 return OutContext.getOrCreateSymbol(NameStr);
2946 }
2947
2948 /// PrintParentLoopComment - Print comments about parent loops of this one.
PrintParentLoopComment(raw_ostream & OS,const MachineLoop * Loop,unsigned FunctionNumber)2949 static void PrintParentLoopComment(raw_ostream &OS, const MachineLoop *Loop,
2950 unsigned FunctionNumber) {
2951 if (!Loop) return;
2952 PrintParentLoopComment(OS, Loop->getParentLoop(), FunctionNumber);
2953 OS.indent(Loop->getLoopDepth()*2)
2954 << "Parent Loop BB" << FunctionNumber << "_"
2955 << Loop->getHeader()->getNumber()
2956 << " Depth=" << Loop->getLoopDepth() << '\n';
2957 }
2958
2959 /// PrintChildLoopComment - Print comments about child loops within
2960 /// the loop for this basic block, with nesting.
PrintChildLoopComment(raw_ostream & OS,const MachineLoop * Loop,unsigned FunctionNumber)2961 static void PrintChildLoopComment(raw_ostream &OS, const MachineLoop *Loop,
2962 unsigned FunctionNumber) {
2963 // Add child loop information
2964 for (const MachineLoop *CL : *Loop) {
2965 OS.indent(CL->getLoopDepth()*2)
2966 << "Child Loop BB" << FunctionNumber << "_"
2967 << CL->getHeader()->getNumber() << " Depth " << CL->getLoopDepth()
2968 << '\n';
2969 PrintChildLoopComment(OS, CL, FunctionNumber);
2970 }
2971 }
2972
2973 /// emitBasicBlockLoopComments - Pretty-print comments for basic blocks.
emitBasicBlockLoopComments(const MachineBasicBlock & MBB,const MachineLoopInfo * LI,const AsmPrinter & AP)2974 static void emitBasicBlockLoopComments(const MachineBasicBlock &MBB,
2975 const MachineLoopInfo *LI,
2976 const AsmPrinter &AP) {
2977 // Add loop depth information
2978 const MachineLoop *Loop = LI->getLoopFor(&MBB);
2979 if (!Loop) return;
2980
2981 MachineBasicBlock *Header = Loop->getHeader();
2982 assert(Header && "No header for loop");
2983
2984 // If this block is not a loop header, just print out what is the loop header
2985 // and return.
2986 if (Header != &MBB) {
2987 AP.OutStreamer->AddComment(" in Loop: Header=BB" +
2988 Twine(AP.getFunctionNumber())+"_" +
2989 Twine(Loop->getHeader()->getNumber())+
2990 " Depth="+Twine(Loop->getLoopDepth()));
2991 return;
2992 }
2993
2994 // Otherwise, it is a loop header. Print out information about child and
2995 // parent loops.
2996 raw_ostream &OS = AP.OutStreamer->GetCommentOS();
2997
2998 PrintParentLoopComment(OS, Loop->getParentLoop(), AP.getFunctionNumber());
2999
3000 OS << "=>";
3001 OS.indent(Loop->getLoopDepth()*2-2);
3002
3003 OS << "This ";
3004 if (Loop->empty())
3005 OS << "Inner ";
3006 OS << "Loop Header: Depth=" + Twine(Loop->getLoopDepth()) << '\n';
3007
3008 PrintChildLoopComment(OS, Loop, AP.getFunctionNumber());
3009 }
3010
3011 /// emitBasicBlockStart - This method prints the label for the specified
3012 /// MachineBasicBlock, an alignment (if present) and a comment describing
3013 /// it if appropriate.
emitBasicBlockStart(const MachineBasicBlock & MBB)3014 void AsmPrinter::emitBasicBlockStart(const MachineBasicBlock &MBB) {
3015 // End the previous funclet and start a new one.
3016 if (MBB.isEHFuncletEntry()) {
3017 for (const HandlerInfo &HI : Handlers) {
3018 HI.Handler->endFunclet();
3019 HI.Handler->beginFunclet(MBB);
3020 }
3021 }
3022
3023 // Emit an alignment directive for this block, if needed.
3024 const Align Alignment = MBB.getAlignment();
3025 if (Alignment != Align(1))
3026 emitAlignment(Alignment);
3027
3028 // If the block has its address taken, emit any labels that were used to
3029 // reference the block. It is possible that there is more than one label
3030 // here, because multiple LLVM BB's may have been RAUW'd to this block after
3031 // the references were generated.
3032 if (MBB.hasAddressTaken()) {
3033 const BasicBlock *BB = MBB.getBasicBlock();
3034 if (isVerbose())
3035 OutStreamer->AddComment("Block address taken");
3036
3037 // MBBs can have their address taken as part of CodeGen without having
3038 // their corresponding BB's address taken in IR
3039 if (BB->hasAddressTaken())
3040 for (MCSymbol *Sym : MMI->getAddrLabelSymbolToEmit(BB))
3041 OutStreamer->emitLabel(Sym);
3042 }
3043
3044 // Print some verbose block comments.
3045 if (isVerbose()) {
3046 if (const BasicBlock *BB = MBB.getBasicBlock()) {
3047 if (BB->hasName()) {
3048 BB->printAsOperand(OutStreamer->GetCommentOS(),
3049 /*PrintType=*/false, BB->getModule());
3050 OutStreamer->GetCommentOS() << '\n';
3051 }
3052 }
3053
3054 assert(MLI != nullptr && "MachineLoopInfo should has been computed");
3055 emitBasicBlockLoopComments(MBB, MLI, *this);
3056 }
3057
3058 if (MBB.pred_empty() ||
3059 (!MF->hasBBLabels() && isBlockOnlyReachableByFallthrough(&MBB) &&
3060 !MBB.isEHFuncletEntry() && !MBB.hasLabelMustBeEmitted())) {
3061 if (isVerbose()) {
3062 // NOTE: Want this comment at start of line, don't emit with AddComment.
3063 OutStreamer->emitRawComment(" %bb." + Twine(MBB.getNumber()) + ":",
3064 false);
3065 }
3066 } else {
3067 if (isVerbose() && MBB.hasLabelMustBeEmitted()) {
3068 OutStreamer->AddComment("Label of block must be emitted");
3069 }
3070 auto *BBSymbol = MBB.getSymbol();
3071 // Switch to a new section if this basic block must begin a section.
3072 if (MBB.isBeginSection()) {
3073 OutStreamer->SwitchSection(
3074 getObjFileLowering().getSectionForMachineBasicBlock(MF->getFunction(),
3075 MBB, TM));
3076 CurrentSectionBeginSym = BBSymbol;
3077 }
3078 OutStreamer->emitLabel(BBSymbol);
3079 // With BB sections, each basic block must handle CFI information on its own
3080 // if it begins a section.
3081 if (MBB.isBeginSection())
3082 for (const HandlerInfo &HI : Handlers)
3083 HI.Handler->beginBasicBlock(MBB);
3084 }
3085 }
3086
emitBasicBlockEnd(const MachineBasicBlock & MBB)3087 void AsmPrinter::emitBasicBlockEnd(const MachineBasicBlock &MBB) {
3088 // Check if CFI information needs to be updated for this MBB with basic block
3089 // sections.
3090 if (MBB.isEndSection())
3091 for (const HandlerInfo &HI : Handlers)
3092 HI.Handler->endBasicBlock(MBB);
3093 }
3094
emitVisibility(MCSymbol * Sym,unsigned Visibility,bool IsDefinition) const3095 void AsmPrinter::emitVisibility(MCSymbol *Sym, unsigned Visibility,
3096 bool IsDefinition) const {
3097 MCSymbolAttr Attr = MCSA_Invalid;
3098
3099 switch (Visibility) {
3100 default: break;
3101 case GlobalValue::HiddenVisibility:
3102 if (IsDefinition)
3103 Attr = MAI->getHiddenVisibilityAttr();
3104 else
3105 Attr = MAI->getHiddenDeclarationVisibilityAttr();
3106 break;
3107 case GlobalValue::ProtectedVisibility:
3108 Attr = MAI->getProtectedVisibilityAttr();
3109 break;
3110 }
3111
3112 if (Attr != MCSA_Invalid)
3113 OutStreamer->emitSymbolAttribute(Sym, Attr);
3114 }
3115
3116 /// isBlockOnlyReachableByFallthough - Return true if the basic block has
3117 /// exactly one predecessor and the control transfer mechanism between
3118 /// the predecessor and this block is a fall-through.
3119 bool AsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock * MBB) const3120 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
3121 // With BasicBlock Sections, beginning of the section is not a fallthrough.
3122 if (MBB->isBeginSection())
3123 return false;
3124
3125 // If this is a landing pad, it isn't a fall through. If it has no preds,
3126 // then nothing falls through to it.
3127 if (MBB->isEHPad() || MBB->pred_empty())
3128 return false;
3129
3130 // If there isn't exactly one predecessor, it can't be a fall through.
3131 if (MBB->pred_size() > 1)
3132 return false;
3133
3134 // The predecessor has to be immediately before this block.
3135 MachineBasicBlock *Pred = *MBB->pred_begin();
3136 if (!Pred->isLayoutSuccessor(MBB))
3137 return false;
3138
3139 // If the block is completely empty, then it definitely does fall through.
3140 if (Pred->empty())
3141 return true;
3142
3143 // Check the terminators in the previous blocks
3144 for (const auto &MI : Pred->terminators()) {
3145 // If it is not a simple branch, we are in a table somewhere.
3146 if (!MI.isBranch() || MI.isIndirectBranch())
3147 return false;
3148
3149 // If we are the operands of one of the branches, this is not a fall
3150 // through. Note that targets with delay slots will usually bundle
3151 // terminators with the delay slot instruction.
3152 for (ConstMIBundleOperands OP(MI); OP.isValid(); ++OP) {
3153 if (OP->isJTI())
3154 return false;
3155 if (OP->isMBB() && OP->getMBB() == MBB)
3156 return false;
3157 }
3158 }
3159
3160 return true;
3161 }
3162
GetOrCreateGCPrinter(GCStrategy & S)3163 GCMetadataPrinter *AsmPrinter::GetOrCreateGCPrinter(GCStrategy &S) {
3164 if (!S.usesMetadata())
3165 return nullptr;
3166
3167 gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
3168 gcp_map_type::iterator GCPI = GCMap.find(&S);
3169 if (GCPI != GCMap.end())
3170 return GCPI->second.get();
3171
3172 auto Name = S.getName();
3173
3174 for (const GCMetadataPrinterRegistry::entry &GCMetaPrinter :
3175 GCMetadataPrinterRegistry::entries())
3176 if (Name == GCMetaPrinter.getName()) {
3177 std::unique_ptr<GCMetadataPrinter> GMP = GCMetaPrinter.instantiate();
3178 GMP->S = &S;
3179 auto IterBool = GCMap.insert(std::make_pair(&S, std::move(GMP)));
3180 return IterBool.first->second.get();
3181 }
3182
3183 report_fatal_error("no GCMetadataPrinter registered for GC: " + Twine(Name));
3184 }
3185
emitStackMaps(StackMaps & SM)3186 void AsmPrinter::emitStackMaps(StackMaps &SM) {
3187 GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
3188 assert(MI && "AsmPrinter didn't require GCModuleInfo?");
3189 bool NeedsDefault = false;
3190 if (MI->begin() == MI->end())
3191 // No GC strategy, use the default format.
3192 NeedsDefault = true;
3193 else
3194 for (auto &I : *MI) {
3195 if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(*I))
3196 if (MP->emitStackMaps(SM, *this))
3197 continue;
3198 // The strategy doesn't have printer or doesn't emit custom stack maps.
3199 // Use the default format.
3200 NeedsDefault = true;
3201 }
3202
3203 if (NeedsDefault)
3204 SM.serializeToStackMapSection();
3205 }
3206
3207 /// Pin vtable to this file.
3208 AsmPrinterHandler::~AsmPrinterHandler() = default;
3209
markFunctionEnd()3210 void AsmPrinterHandler::markFunctionEnd() {}
3211
3212 // In the binary's "xray_instr_map" section, an array of these function entries
3213 // describes each instrumentation point. When XRay patches your code, the index
3214 // into this table will be given to your handler as a patch point identifier.
emit(int Bytes,MCStreamer * Out) const3215 void AsmPrinter::XRayFunctionEntry::emit(int Bytes, MCStreamer *Out) const {
3216 auto Kind8 = static_cast<uint8_t>(Kind);
3217 Out->emitBinaryData(StringRef(reinterpret_cast<const char *>(&Kind8), 1));
3218 Out->emitBinaryData(
3219 StringRef(reinterpret_cast<const char *>(&AlwaysInstrument), 1));
3220 Out->emitBinaryData(StringRef(reinterpret_cast<const char *>(&Version), 1));
3221 auto Padding = (4 * Bytes) - ((2 * Bytes) + 3);
3222 assert(Padding >= 0 && "Instrumentation map entry > 4 * Word Size");
3223 Out->emitZeros(Padding);
3224 }
3225
emitXRayTable()3226 void AsmPrinter::emitXRayTable() {
3227 if (Sleds.empty())
3228 return;
3229
3230 auto PrevSection = OutStreamer->getCurrentSectionOnly();
3231 const Function &F = MF->getFunction();
3232 MCSection *InstMap = nullptr;
3233 MCSection *FnSledIndex = nullptr;
3234 const Triple &TT = TM.getTargetTriple();
3235 // Use PC-relative addresses on all targets except MIPS (MIPS64 cannot use
3236 // PC-relative addresses because R_MIPS_PC64 does not exist).
3237 bool PCRel = !TT.isMIPS();
3238 if (TT.isOSBinFormatELF()) {
3239 auto LinkedToSym = cast<MCSymbolELF>(CurrentFnSym);
3240 auto Flags = ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER;
3241 if (!PCRel)
3242 Flags |= ELF::SHF_WRITE;
3243 StringRef GroupName;
3244 if (F.hasComdat()) {
3245 Flags |= ELF::SHF_GROUP;
3246 GroupName = F.getComdat()->getName();
3247 }
3248 InstMap = OutContext.getELFSection("xray_instr_map", ELF::SHT_PROGBITS,
3249 Flags, 0, GroupName,
3250 MCSection::NonUniqueID, LinkedToSym);
3251
3252 if (!TM.Options.XRayOmitFunctionIndex)
3253 FnSledIndex = OutContext.getELFSection(
3254 "xray_fn_idx", ELF::SHT_PROGBITS, Flags | ELF::SHF_WRITE, 0,
3255 GroupName, MCSection::NonUniqueID, LinkedToSym);
3256 } else if (MF->getSubtarget().getTargetTriple().isOSBinFormatMachO()) {
3257 InstMap = OutContext.getMachOSection("__DATA", "xray_instr_map", 0,
3258 SectionKind::getReadOnlyWithRel());
3259 if (!TM.Options.XRayOmitFunctionIndex)
3260 FnSledIndex = OutContext.getMachOSection(
3261 "__DATA", "xray_fn_idx", 0, SectionKind::getReadOnlyWithRel());
3262 } else {
3263 llvm_unreachable("Unsupported target");
3264 }
3265
3266 auto WordSizeBytes = MAI->getCodePointerSize();
3267
3268 // Now we switch to the instrumentation map section. Because this is done
3269 // per-function, we are able to create an index entry that will represent the
3270 // range of sleds associated with a function.
3271 auto &Ctx = OutContext;
3272 MCSymbol *SledsStart = OutContext.createTempSymbol("xray_sleds_start", true);
3273 OutStreamer->SwitchSection(InstMap);
3274 OutStreamer->emitLabel(SledsStart);
3275 for (const auto &Sled : Sleds) {
3276 if (PCRel) {
3277 MCSymbol *Dot = Ctx.createTempSymbol();
3278 OutStreamer->emitLabel(Dot);
3279 OutStreamer->emitValueImpl(
3280 MCBinaryExpr::createSub(MCSymbolRefExpr::create(Sled.Sled, Ctx),
3281 MCSymbolRefExpr::create(Dot, Ctx), Ctx),
3282 WordSizeBytes);
3283 OutStreamer->emitValueImpl(
3284 MCBinaryExpr::createSub(
3285 MCSymbolRefExpr::create(CurrentFnBegin, Ctx),
3286 MCBinaryExpr::createAdd(
3287 MCSymbolRefExpr::create(Dot, Ctx),
3288 MCConstantExpr::create(WordSizeBytes, Ctx), Ctx),
3289 Ctx),
3290 WordSizeBytes);
3291 } else {
3292 OutStreamer->emitSymbolValue(Sled.Sled, WordSizeBytes);
3293 OutStreamer->emitSymbolValue(CurrentFnSym, WordSizeBytes);
3294 }
3295 Sled.emit(WordSizeBytes, OutStreamer.get());
3296 }
3297 MCSymbol *SledsEnd = OutContext.createTempSymbol("xray_sleds_end", true);
3298 OutStreamer->emitLabel(SledsEnd);
3299
3300 // We then emit a single entry in the index per function. We use the symbols
3301 // that bound the instrumentation map as the range for a specific function.
3302 // Each entry here will be 2 * word size aligned, as we're writing down two
3303 // pointers. This should work for both 32-bit and 64-bit platforms.
3304 if (FnSledIndex) {
3305 OutStreamer->SwitchSection(FnSledIndex);
3306 OutStreamer->emitCodeAlignment(2 * WordSizeBytes);
3307 OutStreamer->emitSymbolValue(SledsStart, WordSizeBytes, false);
3308 OutStreamer->emitSymbolValue(SledsEnd, WordSizeBytes, false);
3309 OutStreamer->SwitchSection(PrevSection);
3310 }
3311 Sleds.clear();
3312 }
3313
recordSled(MCSymbol * Sled,const MachineInstr & MI,SledKind Kind,uint8_t Version)3314 void AsmPrinter::recordSled(MCSymbol *Sled, const MachineInstr &MI,
3315 SledKind Kind, uint8_t Version) {
3316 const Function &F = MI.getMF()->getFunction();
3317 auto Attr = F.getFnAttribute("function-instrument");
3318 bool LogArgs = F.hasFnAttribute("xray-log-args");
3319 bool AlwaysInstrument =
3320 Attr.isStringAttribute() && Attr.getValueAsString() == "xray-always";
3321 if (Kind == SledKind::FUNCTION_ENTER && LogArgs)
3322 Kind = SledKind::LOG_ARGS_ENTER;
3323 Sleds.emplace_back(XRayFunctionEntry{Sled, CurrentFnSym, Kind,
3324 AlwaysInstrument, &F, Version});
3325 }
3326
emitPatchableFunctionEntries()3327 void AsmPrinter::emitPatchableFunctionEntries() {
3328 const Function &F = MF->getFunction();
3329 unsigned PatchableFunctionPrefix = 0, PatchableFunctionEntry = 0;
3330 (void)F.getFnAttribute("patchable-function-prefix")
3331 .getValueAsString()
3332 .getAsInteger(10, PatchableFunctionPrefix);
3333 (void)F.getFnAttribute("patchable-function-entry")
3334 .getValueAsString()
3335 .getAsInteger(10, PatchableFunctionEntry);
3336 if (!PatchableFunctionPrefix && !PatchableFunctionEntry)
3337 return;
3338 const unsigned PointerSize = getPointerSize();
3339 if (TM.getTargetTriple().isOSBinFormatELF()) {
3340 auto Flags = ELF::SHF_WRITE | ELF::SHF_ALLOC;
3341 const MCSymbolELF *LinkedToSym = nullptr;
3342 StringRef GroupName;
3343
3344 // GNU as < 2.35 did not support section flag 'o'. Use SHF_LINK_ORDER only
3345 // if we are using the integrated assembler.
3346 if (MAI->useIntegratedAssembler()) {
3347 Flags |= ELF::SHF_LINK_ORDER;
3348 if (F.hasComdat()) {
3349 Flags |= ELF::SHF_GROUP;
3350 GroupName = F.getComdat()->getName();
3351 }
3352 LinkedToSym = cast<MCSymbolELF>(CurrentFnSym);
3353 }
3354 OutStreamer->SwitchSection(OutContext.getELFSection(
3355 "__patchable_function_entries", ELF::SHT_PROGBITS, Flags, 0, GroupName,
3356 MCSection::NonUniqueID, LinkedToSym));
3357 emitAlignment(Align(PointerSize));
3358 OutStreamer->emitSymbolValue(CurrentPatchableFunctionEntrySym, PointerSize);
3359 }
3360 }
3361
getDwarfVersion() const3362 uint16_t AsmPrinter::getDwarfVersion() const {
3363 return OutStreamer->getContext().getDwarfVersion();
3364 }
3365
setDwarfVersion(uint16_t Version)3366 void AsmPrinter::setDwarfVersion(uint16_t Version) {
3367 OutStreamer->getContext().setDwarfVersion(Version);
3368 }
3369