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1 //===-- AsmPrinter.cpp - Common AsmPrinter code ---------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the AsmPrinter class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/CodeGen/AsmPrinter.h"
15 #include "DwarfDebug.h"
16 #include "DwarfException.h"
17 #include "WinCodeViewLineTables.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/Analysis/ConstantFolding.h"
21 #include "llvm/Analysis/JumpInstrTableInfo.h"
22 #include "llvm/CodeGen/GCMetadataPrinter.h"
23 #include "llvm/CodeGen/MachineConstantPool.h"
24 #include "llvm/CodeGen/MachineFrameInfo.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineInstrBundle.h"
27 #include "llvm/CodeGen/MachineJumpTableInfo.h"
28 #include "llvm/CodeGen/MachineLoopInfo.h"
29 #include "llvm/CodeGen/MachineModuleInfo.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/DebugInfo.h"
32 #include "llvm/IR/Mangler.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Operator.h"
35 #include "llvm/MC/MCAsmInfo.h"
36 #include "llvm/MC/MCContext.h"
37 #include "llvm/MC/MCExpr.h"
38 #include "llvm/MC/MCInst.h"
39 #include "llvm/MC/MCSection.h"
40 #include "llvm/MC/MCStreamer.h"
41 #include "llvm/MC/MCSymbol.h"
42 #include "llvm/Support/ErrorHandling.h"
43 #include "llvm/Support/Format.h"
44 #include "llvm/Support/MathExtras.h"
45 #include "llvm/Support/Timer.h"
46 #include "llvm/Target/TargetFrameLowering.h"
47 #include "llvm/Target/TargetInstrInfo.h"
48 #include "llvm/Target/TargetLowering.h"
49 #include "llvm/Target/TargetLoweringObjectFile.h"
50 #include "llvm/Target/TargetRegisterInfo.h"
51 #include "llvm/Target/TargetSubtargetInfo.h"
52 #include "llvm/Transforms/Utils/GlobalStatus.h"
53 using namespace llvm;
54 
55 #define DEBUG_TYPE "asm-printer"
56 
57 static const char *const DWARFGroupName = "DWARF Emission";
58 static const char *const DbgTimerName = "Debug Info Emission";
59 static const char *const EHTimerName = "DWARF Exception Writer";
60 static const char *const CodeViewLineTablesGroupName = "CodeView Line Tables";
61 
62 STATISTIC(EmittedInsts, "Number of machine instrs printed");
63 
64 char AsmPrinter::ID = 0;
65 
66 typedef DenseMap<GCStrategy*, std::unique_ptr<GCMetadataPrinter>> gcp_map_type;
getGCMap(void * & P)67 static gcp_map_type &getGCMap(void *&P) {
68   if (!P)
69     P = new gcp_map_type();
70   return *(gcp_map_type*)P;
71 }
72 
73 
74 /// getGVAlignmentLog2 - Return the alignment to use for the specified global
75 /// value in log2 form.  This rounds up to the preferred alignment if possible
76 /// and legal.
getGVAlignmentLog2(const GlobalValue * GV,const DataLayout & TD,unsigned InBits=0)77 static unsigned getGVAlignmentLog2(const GlobalValue *GV, const DataLayout &TD,
78                                    unsigned InBits = 0) {
79   unsigned NumBits = 0;
80   if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
81     NumBits = TD.getPreferredAlignmentLog(GVar);
82 
83   // If InBits is specified, round it to it.
84   if (InBits > NumBits)
85     NumBits = InBits;
86 
87   // If the GV has a specified alignment, take it into account.
88   if (GV->getAlignment() == 0)
89     return NumBits;
90 
91   unsigned GVAlign = Log2_32(GV->getAlignment());
92 
93   // If the GVAlign is larger than NumBits, or if we are required to obey
94   // NumBits because the GV has an assigned section, obey it.
95   if (GVAlign > NumBits || GV->hasSection())
96     NumBits = GVAlign;
97   return NumBits;
98 }
99 
AsmPrinter(TargetMachine & tm,MCStreamer & Streamer)100 AsmPrinter::AsmPrinter(TargetMachine &tm, MCStreamer &Streamer)
101   : MachineFunctionPass(ID),
102     TM(tm), MAI(tm.getMCAsmInfo()), MII(tm.getInstrInfo()),
103     OutContext(Streamer.getContext()),
104     OutStreamer(Streamer),
105     LastMI(nullptr), LastFn(0), Counter(~0U), SetCounter(0) {
106   DD = nullptr; MMI = nullptr; LI = nullptr; MF = nullptr;
107   CurrentFnSym = CurrentFnSymForSize = nullptr;
108   GCMetadataPrinters = nullptr;
109   VerboseAsm = Streamer.isVerboseAsm();
110 }
111 
~AsmPrinter()112 AsmPrinter::~AsmPrinter() {
113   assert(!DD && Handlers.empty() && "Debug/EH info didn't get finalized");
114 
115   if (GCMetadataPrinters) {
116     gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
117 
118     delete &GCMap;
119     GCMetadataPrinters = nullptr;
120   }
121 
122   delete &OutStreamer;
123 }
124 
125 /// getFunctionNumber - Return a unique ID for the current function.
126 ///
getFunctionNumber() const127 unsigned AsmPrinter::getFunctionNumber() const {
128   return MF->getFunctionNumber();
129 }
130 
getObjFileLowering() const131 const TargetLoweringObjectFile &AsmPrinter::getObjFileLowering() const {
132   return TM.getTargetLowering()->getObjFileLowering();
133 }
134 
135 /// getDataLayout - Return information about data layout.
getDataLayout() const136 const DataLayout &AsmPrinter::getDataLayout() const {
137   return *TM.getDataLayout();
138 }
139 
getSubtargetInfo() const140 const MCSubtargetInfo &AsmPrinter::getSubtargetInfo() const {
141   return TM.getSubtarget<MCSubtargetInfo>();
142 }
143 
EmitToStreamer(MCStreamer & S,const MCInst & Inst)144 void AsmPrinter::EmitToStreamer(MCStreamer &S, const MCInst &Inst) {
145   S.EmitInstruction(Inst, getSubtargetInfo());
146 }
147 
getTargetTriple() const148 StringRef AsmPrinter::getTargetTriple() const {
149   return TM.getTargetTriple();
150 }
151 
152 /// getCurrentSection() - Return the current section we are emitting to.
getCurrentSection() const153 const MCSection *AsmPrinter::getCurrentSection() const {
154   return OutStreamer.getCurrentSection().first;
155 }
156 
157 
158 
getAnalysisUsage(AnalysisUsage & AU) const159 void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
160   AU.setPreservesAll();
161   MachineFunctionPass::getAnalysisUsage(AU);
162   AU.addRequired<MachineModuleInfo>();
163   AU.addRequired<GCModuleInfo>();
164   if (isVerbose())
165     AU.addRequired<MachineLoopInfo>();
166 }
167 
doInitialization(Module & M)168 bool AsmPrinter::doInitialization(Module &M) {
169   MMI = getAnalysisIfAvailable<MachineModuleInfo>();
170   MMI->AnalyzeModule(M);
171 
172   // Initialize TargetLoweringObjectFile.
173   const_cast<TargetLoweringObjectFile&>(getObjFileLowering())
174     .Initialize(OutContext, TM);
175 
176   OutStreamer.InitSections();
177 
178   Mang = new Mangler(TM.getDataLayout());
179 
180   // Emit the version-min deplyment target directive if needed.
181   //
182   // FIXME: If we end up with a collection of these sorts of Darwin-specific
183   // or ELF-specific things, it may make sense to have a platform helper class
184   // that will work with the target helper class. For now keep it here, as the
185   // alternative is duplicated code in each of the target asm printers that
186   // use the directive, where it would need the same conditionalization
187   // anyway.
188   Triple TT(getTargetTriple());
189   if (TT.isOSDarwin()) {
190     unsigned Major, Minor, Update;
191     TT.getOSVersion(Major, Minor, Update);
192     // If there is a version specified, Major will be non-zero.
193     if (Major)
194       OutStreamer.EmitVersionMin((TT.isMacOSX() ?
195                                   MCVM_OSXVersionMin : MCVM_IOSVersionMin),
196                                  Major, Minor, Update);
197   }
198 
199   // Allow the target to emit any magic that it wants at the start of the file.
200   EmitStartOfAsmFile(M);
201 
202   // Very minimal debug info. It is ignored if we emit actual debug info. If we
203   // don't, this at least helps the user find where a global came from.
204   if (MAI->hasSingleParameterDotFile()) {
205     // .file "foo.c"
206     OutStreamer.EmitFileDirective(M.getModuleIdentifier());
207   }
208 
209   GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
210   assert(MI && "AsmPrinter didn't require GCModuleInfo?");
211   for (auto &I : *MI)
212     if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(*I))
213       MP->beginAssembly(*this);
214 
215   // Emit module-level inline asm if it exists.
216   if (!M.getModuleInlineAsm().empty()) {
217     OutStreamer.AddComment("Start of file scope inline assembly");
218     OutStreamer.AddBlankLine();
219     EmitInlineAsm(M.getModuleInlineAsm()+"\n");
220     OutStreamer.AddComment("End of file scope inline assembly");
221     OutStreamer.AddBlankLine();
222   }
223 
224   if (MAI->doesSupportDebugInformation()) {
225     if (Triple(TM.getTargetTriple()).isKnownWindowsMSVCEnvironment()) {
226       Handlers.push_back(HandlerInfo(new WinCodeViewLineTables(this),
227                                      DbgTimerName,
228                                      CodeViewLineTablesGroupName));
229     } else {
230       DD = new DwarfDebug(this, &M);
231       Handlers.push_back(HandlerInfo(DD, DbgTimerName, DWARFGroupName));
232     }
233   }
234 
235   EHStreamer *ES = nullptr;
236   switch (MAI->getExceptionHandlingType()) {
237   case ExceptionHandling::None:
238     break;
239   case ExceptionHandling::SjLj:
240   case ExceptionHandling::DwarfCFI:
241     ES = new DwarfCFIException(this);
242     break;
243   case ExceptionHandling::ARM:
244     ES = new ARMException(this);
245     break;
246   case ExceptionHandling::WinEH:
247     ES = new Win64Exception(this);
248     break;
249   }
250   if (ES)
251     Handlers.push_back(HandlerInfo(ES, EHTimerName, DWARFGroupName));
252   return false;
253 }
254 
canBeHidden(const GlobalValue * GV,const MCAsmInfo & MAI)255 static bool canBeHidden(const GlobalValue *GV, const MCAsmInfo &MAI) {
256   GlobalValue::LinkageTypes Linkage = GV->getLinkage();
257   if (Linkage != GlobalValue::LinkOnceODRLinkage)
258     return false;
259 
260   if (!MAI.hasWeakDefCanBeHiddenDirective())
261     return false;
262 
263   if (GV->hasUnnamedAddr())
264     return true;
265 
266   // This is only used for MachO, so right now it doesn't really matter how
267   // we handle alias. Revisit this once the MachO linker implements aliases.
268   if (isa<GlobalAlias>(GV))
269     return false;
270 
271   // If it is a non constant variable, it needs to be uniqued across shared
272   // objects.
273   if (const GlobalVariable *Var = dyn_cast<GlobalVariable>(GV)) {
274     if (!Var->isConstant())
275       return false;
276   }
277 
278   GlobalStatus GS;
279   if (!GlobalStatus::analyzeGlobal(GV, GS) && !GS.IsCompared)
280     return true;
281 
282   return false;
283 }
284 
EmitLinkage(const GlobalValue * GV,MCSymbol * GVSym) const285 void AsmPrinter::EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
286   GlobalValue::LinkageTypes Linkage = GV->getLinkage();
287   switch (Linkage) {
288   case GlobalValue::CommonLinkage:
289   case GlobalValue::LinkOnceAnyLinkage:
290   case GlobalValue::LinkOnceODRLinkage:
291   case GlobalValue::WeakAnyLinkage:
292   case GlobalValue::WeakODRLinkage:
293     if (MAI->hasWeakDefDirective()) {
294       // .globl _foo
295       OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
296 
297       if (!canBeHidden(GV, *MAI))
298         // .weak_definition _foo
299         OutStreamer.EmitSymbolAttribute(GVSym, MCSA_WeakDefinition);
300       else
301         OutStreamer.EmitSymbolAttribute(GVSym, MCSA_WeakDefAutoPrivate);
302     } else if (MAI->hasLinkOnceDirective()) {
303       // .globl _foo
304       OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
305       //NOTE: linkonce is handled by the section the symbol was assigned to.
306     } else {
307       // .weak _foo
308       OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Weak);
309     }
310     return;
311   case GlobalValue::AppendingLinkage:
312     // FIXME: appending linkage variables should go into a section of
313     // their name or something.  For now, just emit them as external.
314   case GlobalValue::ExternalLinkage:
315     // If external or appending, declare as a global symbol.
316     // .globl _foo
317     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
318     return;
319   case GlobalValue::PrivateLinkage:
320   case GlobalValue::InternalLinkage:
321     return;
322   case GlobalValue::AvailableExternallyLinkage:
323     llvm_unreachable("Should never emit this");
324   case GlobalValue::ExternalWeakLinkage:
325     llvm_unreachable("Don't know how to emit these");
326   }
327   llvm_unreachable("Unknown linkage type!");
328 }
329 
getNameWithPrefix(SmallVectorImpl<char> & Name,const GlobalValue * GV) const330 void AsmPrinter::getNameWithPrefix(SmallVectorImpl<char> &Name,
331                                    const GlobalValue *GV) const {
332   TM.getNameWithPrefix(Name, GV, *Mang);
333 }
334 
getSymbol(const GlobalValue * GV) const335 MCSymbol *AsmPrinter::getSymbol(const GlobalValue *GV) const {
336   return TM.getSymbol(GV, *Mang);
337 }
338 
339 /// EmitGlobalVariable - Emit the specified global variable to the .s file.
EmitGlobalVariable(const GlobalVariable * GV)340 void AsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
341   if (GV->hasInitializer()) {
342     // Check to see if this is a special global used by LLVM, if so, emit it.
343     if (EmitSpecialLLVMGlobal(GV))
344       return;
345 
346     if (isVerbose()) {
347       GV->printAsOperand(OutStreamer.GetCommentOS(),
348                      /*PrintType=*/false, GV->getParent());
349       OutStreamer.GetCommentOS() << '\n';
350     }
351   }
352 
353   MCSymbol *GVSym = getSymbol(GV);
354   EmitVisibility(GVSym, GV->getVisibility(), !GV->isDeclaration());
355 
356   if (!GV->hasInitializer())   // External globals require no extra code.
357     return;
358 
359   if (MAI->hasDotTypeDotSizeDirective())
360     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_ELF_TypeObject);
361 
362   SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
363 
364   const DataLayout *DL = TM.getDataLayout();
365   uint64_t Size = DL->getTypeAllocSize(GV->getType()->getElementType());
366 
367   // If the alignment is specified, we *must* obey it.  Overaligning a global
368   // with a specified alignment is a prompt way to break globals emitted to
369   // sections and expected to be contiguous (e.g. ObjC metadata).
370   unsigned AlignLog = getGVAlignmentLog2(GV, *DL);
371 
372   for (const HandlerInfo &HI : Handlers) {
373     NamedRegionTimer T(HI.TimerName, HI.TimerGroupName, TimePassesIsEnabled);
374     HI.Handler->setSymbolSize(GVSym, Size);
375   }
376 
377   // Handle common and BSS local symbols (.lcomm).
378   if (GVKind.isCommon() || GVKind.isBSSLocal()) {
379     if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
380     unsigned Align = 1 << AlignLog;
381 
382     // Handle common symbols.
383     if (GVKind.isCommon()) {
384       if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
385         Align = 0;
386 
387       // .comm _foo, 42, 4
388       OutStreamer.EmitCommonSymbol(GVSym, Size, Align);
389       return;
390     }
391 
392     // Handle local BSS symbols.
393     if (MAI->hasMachoZeroFillDirective()) {
394       const MCSection *TheSection =
395         getObjFileLowering().SectionForGlobal(GV, GVKind, *Mang, TM);
396       // .zerofill __DATA, __bss, _foo, 400, 5
397       OutStreamer.EmitZerofill(TheSection, GVSym, Size, Align);
398       return;
399     }
400 
401     // Use .lcomm only if it supports user-specified alignment.
402     // Otherwise, while it would still be correct to use .lcomm in some
403     // cases (e.g. when Align == 1), the external assembler might enfore
404     // some -unknown- default alignment behavior, which could cause
405     // spurious differences between external and integrated assembler.
406     // Prefer to simply fall back to .local / .comm in this case.
407     if (MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
408       // .lcomm _foo, 42
409       OutStreamer.EmitLocalCommonSymbol(GVSym, Size, Align);
410       return;
411     }
412 
413     if (!getObjFileLowering().getCommDirectiveSupportsAlignment())
414       Align = 0;
415 
416     // .local _foo
417     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Local);
418     // .comm _foo, 42, 4
419     OutStreamer.EmitCommonSymbol(GVSym, Size, Align);
420     return;
421   }
422 
423   const MCSection *TheSection =
424     getObjFileLowering().SectionForGlobal(GV, GVKind, *Mang, TM);
425 
426   // Handle the zerofill directive on darwin, which is a special form of BSS
427   // emission.
428   if (GVKind.isBSSExtern() && MAI->hasMachoZeroFillDirective()) {
429     if (Size == 0) Size = 1;  // zerofill of 0 bytes is undefined.
430 
431     // .globl _foo
432     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
433     // .zerofill __DATA, __common, _foo, 400, 5
434     OutStreamer.EmitZerofill(TheSection, GVSym, Size, 1 << AlignLog);
435     return;
436   }
437 
438   // Handle thread local data for mach-o which requires us to output an
439   // additional structure of data and mangle the original symbol so that we
440   // can reference it later.
441   //
442   // TODO: This should become an "emit thread local global" method on TLOF.
443   // All of this macho specific stuff should be sunk down into TLOFMachO and
444   // stuff like "TLSExtraDataSection" should no longer be part of the parent
445   // TLOF class.  This will also make it more obvious that stuff like
446   // MCStreamer::EmitTBSSSymbol is macho specific and only called from macho
447   // specific code.
448   if (GVKind.isThreadLocal() && MAI->hasMachoTBSSDirective()) {
449     // Emit the .tbss symbol
450     MCSymbol *MangSym =
451       OutContext.GetOrCreateSymbol(GVSym->getName() + Twine("$tlv$init"));
452 
453     if (GVKind.isThreadBSS()) {
454       TheSection = getObjFileLowering().getTLSBSSSection();
455       OutStreamer.EmitTBSSSymbol(TheSection, MangSym, Size, 1 << AlignLog);
456     } else if (GVKind.isThreadData()) {
457       OutStreamer.SwitchSection(TheSection);
458 
459       EmitAlignment(AlignLog, GV);
460       OutStreamer.EmitLabel(MangSym);
461 
462       EmitGlobalConstant(GV->getInitializer());
463     }
464 
465     OutStreamer.AddBlankLine();
466 
467     // Emit the variable struct for the runtime.
468     const MCSection *TLVSect
469       = getObjFileLowering().getTLSExtraDataSection();
470 
471     OutStreamer.SwitchSection(TLVSect);
472     // Emit the linkage here.
473     EmitLinkage(GV, GVSym);
474     OutStreamer.EmitLabel(GVSym);
475 
476     // Three pointers in size:
477     //   - __tlv_bootstrap - used to make sure support exists
478     //   - spare pointer, used when mapped by the runtime
479     //   - pointer to mangled symbol above with initializer
480     unsigned PtrSize = DL->getPointerTypeSize(GV->getType());
481     OutStreamer.EmitSymbolValue(GetExternalSymbolSymbol("_tlv_bootstrap"),
482                                 PtrSize);
483     OutStreamer.EmitIntValue(0, PtrSize);
484     OutStreamer.EmitSymbolValue(MangSym, PtrSize);
485 
486     OutStreamer.AddBlankLine();
487     return;
488   }
489 
490   OutStreamer.SwitchSection(TheSection);
491 
492   EmitLinkage(GV, GVSym);
493   EmitAlignment(AlignLog, GV);
494 
495   OutStreamer.EmitLabel(GVSym);
496 
497   EmitGlobalConstant(GV->getInitializer());
498 
499   if (MAI->hasDotTypeDotSizeDirective())
500     // .size foo, 42
501     OutStreamer.EmitELFSize(GVSym, MCConstantExpr::Create(Size, OutContext));
502 
503   OutStreamer.AddBlankLine();
504 }
505 
506 /// EmitFunctionHeader - This method emits the header for the current
507 /// function.
EmitFunctionHeader()508 void AsmPrinter::EmitFunctionHeader() {
509   // Print out constants referenced by the function
510   EmitConstantPool();
511 
512   // Print the 'header' of function.
513   const Function *F = MF->getFunction();
514 
515   OutStreamer.SwitchSection(
516       getObjFileLowering().SectionForGlobal(F, *Mang, TM));
517   EmitVisibility(CurrentFnSym, F->getVisibility());
518 
519   EmitLinkage(F, CurrentFnSym);
520   EmitAlignment(MF->getAlignment(), F);
521 
522   if (MAI->hasDotTypeDotSizeDirective())
523     OutStreamer.EmitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
524 
525   if (isVerbose()) {
526     F->printAsOperand(OutStreamer.GetCommentOS(),
527                    /*PrintType=*/false, F->getParent());
528     OutStreamer.GetCommentOS() << '\n';
529   }
530 
531   // Emit the CurrentFnSym.  This is a virtual function to allow targets to
532   // do their wild and crazy things as required.
533   EmitFunctionEntryLabel();
534 
535   // If the function had address-taken blocks that got deleted, then we have
536   // references to the dangling symbols.  Emit them at the start of the function
537   // so that we don't get references to undefined symbols.
538   std::vector<MCSymbol*> DeadBlockSyms;
539   MMI->takeDeletedSymbolsForFunction(F, DeadBlockSyms);
540   for (unsigned i = 0, e = DeadBlockSyms.size(); i != e; ++i) {
541     OutStreamer.AddComment("Address taken block that was later removed");
542     OutStreamer.EmitLabel(DeadBlockSyms[i]);
543   }
544 
545   // Emit pre-function debug and/or EH information.
546   for (const HandlerInfo &HI : Handlers) {
547     NamedRegionTimer T(HI.TimerName, HI.TimerGroupName, TimePassesIsEnabled);
548     HI.Handler->beginFunction(MF);
549   }
550 
551   // Emit the prefix data.
552   if (F->hasPrefixData())
553     EmitGlobalConstant(F->getPrefixData());
554 }
555 
556 /// EmitFunctionEntryLabel - Emit the label that is the entrypoint for the
557 /// function.  This can be overridden by targets as required to do custom stuff.
EmitFunctionEntryLabel()558 void AsmPrinter::EmitFunctionEntryLabel() {
559   // The function label could have already been emitted if two symbols end up
560   // conflicting due to asm renaming.  Detect this and emit an error.
561   if (CurrentFnSym->isUndefined())
562     return OutStreamer.EmitLabel(CurrentFnSym);
563 
564   report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
565                      "' label emitted multiple times to assembly file");
566 }
567 
568 /// emitComments - Pretty-print comments for instructions.
emitComments(const MachineInstr & MI,raw_ostream & CommentOS)569 static void emitComments(const MachineInstr &MI, raw_ostream &CommentOS) {
570   const MachineFunction *MF = MI.getParent()->getParent();
571   const TargetMachine &TM = MF->getTarget();
572 
573   // Check for spills and reloads
574   int FI;
575 
576   const MachineFrameInfo *FrameInfo = MF->getFrameInfo();
577 
578   // We assume a single instruction only has a spill or reload, not
579   // both.
580   const MachineMemOperand *MMO;
581   if (TM.getInstrInfo()->isLoadFromStackSlotPostFE(&MI, FI)) {
582     if (FrameInfo->isSpillSlotObjectIndex(FI)) {
583       MMO = *MI.memoperands_begin();
584       CommentOS << MMO->getSize() << "-byte Reload\n";
585     }
586   } else if (TM.getInstrInfo()->hasLoadFromStackSlot(&MI, MMO, FI)) {
587     if (FrameInfo->isSpillSlotObjectIndex(FI))
588       CommentOS << MMO->getSize() << "-byte Folded Reload\n";
589   } else if (TM.getInstrInfo()->isStoreToStackSlotPostFE(&MI, FI)) {
590     if (FrameInfo->isSpillSlotObjectIndex(FI)) {
591       MMO = *MI.memoperands_begin();
592       CommentOS << MMO->getSize() << "-byte Spill\n";
593     }
594   } else if (TM.getInstrInfo()->hasStoreToStackSlot(&MI, MMO, FI)) {
595     if (FrameInfo->isSpillSlotObjectIndex(FI))
596       CommentOS << MMO->getSize() << "-byte Folded Spill\n";
597   }
598 
599   // Check for spill-induced copies
600   if (MI.getAsmPrinterFlag(MachineInstr::ReloadReuse))
601     CommentOS << " Reload Reuse\n";
602 }
603 
604 /// emitImplicitDef - This method emits the specified machine instruction
605 /// that is an implicit def.
emitImplicitDef(const MachineInstr * MI) const606 void AsmPrinter::emitImplicitDef(const MachineInstr *MI) const {
607   unsigned RegNo = MI->getOperand(0).getReg();
608   OutStreamer.AddComment(Twine("implicit-def: ") +
609                          TM.getRegisterInfo()->getName(RegNo));
610   OutStreamer.AddBlankLine();
611 }
612 
emitKill(const MachineInstr * MI,AsmPrinter & AP)613 static void emitKill(const MachineInstr *MI, AsmPrinter &AP) {
614   std::string Str = "kill:";
615   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
616     const MachineOperand &Op = MI->getOperand(i);
617     assert(Op.isReg() && "KILL instruction must have only register operands");
618     Str += ' ';
619     Str += AP.TM.getRegisterInfo()->getName(Op.getReg());
620     Str += (Op.isDef() ? "<def>" : "<kill>");
621   }
622   AP.OutStreamer.AddComment(Str);
623   AP.OutStreamer.AddBlankLine();
624 }
625 
626 /// emitDebugValueComment - This method handles the target-independent form
627 /// of DBG_VALUE, returning true if it was able to do so.  A false return
628 /// means the target will need to handle MI in EmitInstruction.
emitDebugValueComment(const MachineInstr * MI,AsmPrinter & AP)629 static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
630   // This code handles only the 3-operand target-independent form.
631   if (MI->getNumOperands() != 3)
632     return false;
633 
634   SmallString<128> Str;
635   raw_svector_ostream OS(Str);
636   OS << "DEBUG_VALUE: ";
637 
638   DIVariable V(MI->getOperand(2).getMetadata());
639   if (V.getContext().isSubprogram()) {
640     StringRef Name = DISubprogram(V.getContext()).getDisplayName();
641     if (!Name.empty())
642       OS << Name << ":";
643   }
644   OS << V.getName() << " <- ";
645 
646   // The second operand is only an offset if it's an immediate.
647   bool Deref = MI->getOperand(0).isReg() && MI->getOperand(1).isImm();
648   int64_t Offset = Deref ? MI->getOperand(1).getImm() : 0;
649 
650   // Register or immediate value. Register 0 means undef.
651   if (MI->getOperand(0).isFPImm()) {
652     APFloat APF = APFloat(MI->getOperand(0).getFPImm()->getValueAPF());
653     if (MI->getOperand(0).getFPImm()->getType()->isFloatTy()) {
654       OS << (double)APF.convertToFloat();
655     } else if (MI->getOperand(0).getFPImm()->getType()->isDoubleTy()) {
656       OS << APF.convertToDouble();
657     } else {
658       // There is no good way to print long double.  Convert a copy to
659       // double.  Ah well, it's only a comment.
660       bool ignored;
661       APF.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven,
662                   &ignored);
663       OS << "(long double) " << APF.convertToDouble();
664     }
665   } else if (MI->getOperand(0).isImm()) {
666     OS << MI->getOperand(0).getImm();
667   } else if (MI->getOperand(0).isCImm()) {
668     MI->getOperand(0).getCImm()->getValue().print(OS, false /*isSigned*/);
669   } else {
670     unsigned Reg;
671     if (MI->getOperand(0).isReg()) {
672       Reg = MI->getOperand(0).getReg();
673     } else {
674       assert(MI->getOperand(0).isFI() && "Unknown operand type");
675       const TargetFrameLowering *TFI = AP.TM.getFrameLowering();
676       Offset += TFI->getFrameIndexReference(*AP.MF,
677                                             MI->getOperand(0).getIndex(), Reg);
678       Deref = true;
679     }
680     if (Reg == 0) {
681       // Suppress offset, it is not meaningful here.
682       OS << "undef";
683       // NOTE: Want this comment at start of line, don't emit with AddComment.
684       AP.OutStreamer.emitRawComment(OS.str());
685       return true;
686     }
687     if (Deref)
688       OS << '[';
689     OS << AP.TM.getRegisterInfo()->getName(Reg);
690   }
691 
692   if (Deref)
693     OS << '+' << Offset << ']';
694 
695   // NOTE: Want this comment at start of line, don't emit with AddComment.
696   AP.OutStreamer.emitRawComment(OS.str());
697   return true;
698 }
699 
needsCFIMoves()700 AsmPrinter::CFIMoveType AsmPrinter::needsCFIMoves() {
701   if (MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI &&
702       MF->getFunction()->needsUnwindTableEntry())
703     return CFI_M_EH;
704 
705   if (MMI->hasDebugInfo())
706     return CFI_M_Debug;
707 
708   return CFI_M_None;
709 }
710 
needsSEHMoves()711 bool AsmPrinter::needsSEHMoves() {
712   return MAI->getExceptionHandlingType() == ExceptionHandling::WinEH &&
713     MF->getFunction()->needsUnwindTableEntry();
714 }
715 
emitCFIInstruction(const MachineInstr & MI)716 void AsmPrinter::emitCFIInstruction(const MachineInstr &MI) {
717   ExceptionHandling ExceptionHandlingType = MAI->getExceptionHandlingType();
718   if (ExceptionHandlingType != ExceptionHandling::DwarfCFI &&
719       ExceptionHandlingType != ExceptionHandling::ARM)
720     return;
721 
722   if (needsCFIMoves() == CFI_M_None)
723     return;
724 
725   if (MMI->getCompactUnwindEncoding() != 0)
726     OutStreamer.EmitCompactUnwindEncoding(MMI->getCompactUnwindEncoding());
727 
728   const MachineModuleInfo &MMI = MF->getMMI();
729   const std::vector<MCCFIInstruction> &Instrs = MMI.getFrameInstructions();
730   unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
731   const MCCFIInstruction &CFI = Instrs[CFIIndex];
732   emitCFIInstruction(CFI);
733 }
734 
735 /// EmitFunctionBody - This method emits the body and trailer for a
736 /// function.
EmitFunctionBody()737 void AsmPrinter::EmitFunctionBody() {
738   // Emit target-specific gunk before the function body.
739   EmitFunctionBodyStart();
740 
741   bool ShouldPrintDebugScopes = MMI->hasDebugInfo();
742 
743   // Print out code for the function.
744   bool HasAnyRealCode = false;
745   const MachineInstr *LastMI = nullptr;
746   for (auto &MBB : *MF) {
747     // Print a label for the basic block.
748     EmitBasicBlockStart(MBB);
749     for (auto &MI : MBB) {
750       LastMI = &MI;
751 
752       // Print the assembly for the instruction.
753       if (!MI.isPosition() && !MI.isImplicitDef() && !MI.isKill() &&
754           !MI.isDebugValue()) {
755         HasAnyRealCode = true;
756         ++EmittedInsts;
757       }
758 
759       if (ShouldPrintDebugScopes) {
760         for (const HandlerInfo &HI : Handlers) {
761           NamedRegionTimer T(HI.TimerName, HI.TimerGroupName,
762                              TimePassesIsEnabled);
763           HI.Handler->beginInstruction(&MI);
764         }
765       }
766 
767       if (isVerbose())
768         emitComments(MI, OutStreamer.GetCommentOS());
769 
770       switch (MI.getOpcode()) {
771       case TargetOpcode::CFI_INSTRUCTION:
772         emitCFIInstruction(MI);
773         break;
774 
775       case TargetOpcode::EH_LABEL:
776       case TargetOpcode::GC_LABEL:
777         OutStreamer.EmitLabel(MI.getOperand(0).getMCSymbol());
778         break;
779       case TargetOpcode::INLINEASM:
780         EmitInlineAsm(&MI);
781         break;
782       case TargetOpcode::DBG_VALUE:
783         if (isVerbose()) {
784           if (!emitDebugValueComment(&MI, *this))
785             EmitInstruction(&MI);
786         }
787         break;
788       case TargetOpcode::IMPLICIT_DEF:
789         if (isVerbose()) emitImplicitDef(&MI);
790         break;
791       case TargetOpcode::KILL:
792         if (isVerbose()) emitKill(&MI, *this);
793         break;
794       default:
795         EmitInstruction(&MI);
796         break;
797       }
798 
799       if (ShouldPrintDebugScopes) {
800         for (const HandlerInfo &HI : Handlers) {
801           NamedRegionTimer T(HI.TimerName, HI.TimerGroupName,
802                              TimePassesIsEnabled);
803           HI.Handler->endInstruction();
804         }
805       }
806     }
807   }
808 
809   // If the last instruction was a prolog label, then we have a situation where
810   // we emitted a prolog but no function body. This results in the ending prolog
811   // label equaling the end of function label and an invalid "row" in the
812   // FDE. We need to emit a noop in this situation so that the FDE's rows are
813   // valid.
814   bool RequiresNoop = LastMI && LastMI->isCFIInstruction();
815 
816   // If the function is empty and the object file uses .subsections_via_symbols,
817   // then we need to emit *something* to the function body to prevent the
818   // labels from collapsing together.  Just emit a noop.
819   if ((MAI->hasSubsectionsViaSymbols() && !HasAnyRealCode) || RequiresNoop) {
820     MCInst Noop;
821     TM.getInstrInfo()->getNoopForMachoTarget(Noop);
822     if (Noop.getOpcode()) {
823       OutStreamer.AddComment("avoids zero-length function");
824       OutStreamer.EmitInstruction(Noop, getSubtargetInfo());
825     } else  // Target not mc-ized yet.
826       OutStreamer.EmitRawText(StringRef("\tnop\n"));
827   }
828 
829   const Function *F = MF->getFunction();
830   for (const auto &BB : *F) {
831     if (!BB.hasAddressTaken())
832       continue;
833     MCSymbol *Sym = GetBlockAddressSymbol(&BB);
834     if (Sym->isDefined())
835       continue;
836     OutStreamer.AddComment("Address of block that was removed by CodeGen");
837     OutStreamer.EmitLabel(Sym);
838   }
839 
840   // Emit target-specific gunk after the function body.
841   EmitFunctionBodyEnd();
842 
843   // If the target wants a .size directive for the size of the function, emit
844   // it.
845   if (MAI->hasDotTypeDotSizeDirective()) {
846     // Create a symbol for the end of function, so we can get the size as
847     // difference between the function label and the temp label.
848     MCSymbol *FnEndLabel = OutContext.CreateTempSymbol();
849     OutStreamer.EmitLabel(FnEndLabel);
850 
851     const MCExpr *SizeExp =
852       MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create(FnEndLabel, OutContext),
853                               MCSymbolRefExpr::Create(CurrentFnSymForSize,
854                                                       OutContext),
855                               OutContext);
856     OutStreamer.EmitELFSize(CurrentFnSym, SizeExp);
857   }
858 
859   // Emit post-function debug and/or EH information.
860   for (const HandlerInfo &HI : Handlers) {
861     NamedRegionTimer T(HI.TimerName, HI.TimerGroupName, TimePassesIsEnabled);
862     HI.Handler->endFunction(MF);
863   }
864   MMI->EndFunction();
865 
866   // Print out jump tables referenced by the function.
867   EmitJumpTableInfo();
868 
869   OutStreamer.AddBlankLine();
870 }
871 
872 static const MCExpr *lowerConstant(const Constant *CV, AsmPrinter &AP);
873 
doFinalization(Module & M)874 bool AsmPrinter::doFinalization(Module &M) {
875   // Emit global variables.
876   for (const auto &G : M.globals())
877     EmitGlobalVariable(&G);
878 
879   // Emit visibility info for declarations
880   for (const Function &F : M) {
881     if (!F.isDeclaration())
882       continue;
883     GlobalValue::VisibilityTypes V = F.getVisibility();
884     if (V == GlobalValue::DefaultVisibility)
885       continue;
886 
887     MCSymbol *Name = getSymbol(&F);
888     EmitVisibility(Name, V, false);
889   }
890 
891   // Get information about jump-instruction tables to print.
892   JumpInstrTableInfo *JITI = getAnalysisIfAvailable<JumpInstrTableInfo>();
893 
894   if (JITI && !JITI->getTables().empty()) {
895     unsigned Arch = Triple(getTargetTriple()).getArch();
896     bool IsThumb = (Arch == Triple::thumb || Arch == Triple::thumbeb);
897     MCInst TrapInst;
898     TM.getInstrInfo()->getTrap(TrapInst);
899     for (const auto &KV : JITI->getTables()) {
900       uint64_t Count = 0;
901       for (const auto &FunPair : KV.second) {
902         // Emit the function labels to make this be a function entry point.
903         MCSymbol *FunSym =
904           OutContext.GetOrCreateSymbol(FunPair.second->getName());
905         OutStreamer.EmitSymbolAttribute(FunSym, MCSA_Global);
906         // FIXME: JumpTableInstrInfo should store information about the required
907         // alignment of table entries and the size of the padding instruction.
908         EmitAlignment(3);
909         if (IsThumb)
910           OutStreamer.EmitThumbFunc(FunSym);
911         if (MAI->hasDotTypeDotSizeDirective())
912           OutStreamer.EmitSymbolAttribute(FunSym, MCSA_ELF_TypeFunction);
913         OutStreamer.EmitLabel(FunSym);
914 
915         // Emit the jump instruction to transfer control to the original
916         // function.
917         MCInst JumpToFun;
918         MCSymbol *TargetSymbol =
919           OutContext.GetOrCreateSymbol(FunPair.first->getName());
920         const MCSymbolRefExpr *TargetSymRef =
921           MCSymbolRefExpr::Create(TargetSymbol, MCSymbolRefExpr::VK_PLT,
922                                   OutContext);
923         TM.getInstrInfo()->getUnconditionalBranch(JumpToFun, TargetSymRef);
924         OutStreamer.EmitInstruction(JumpToFun, getSubtargetInfo());
925         ++Count;
926       }
927 
928       // Emit enough padding instructions to fill up to the next power of two.
929       // This assumes that the trap instruction takes 8 bytes or fewer.
930       uint64_t Remaining = NextPowerOf2(Count) - Count;
931       for (uint64_t C = 0; C < Remaining; ++C) {
932         EmitAlignment(3);
933         OutStreamer.EmitInstruction(TrapInst, getSubtargetInfo());
934       }
935 
936     }
937   }
938 
939   // Emit module flags.
940   SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
941   M.getModuleFlagsMetadata(ModuleFlags);
942   if (!ModuleFlags.empty())
943     getObjFileLowering().emitModuleFlags(OutStreamer, ModuleFlags, *Mang, TM);
944 
945   // Make sure we wrote out everything we need.
946   OutStreamer.Flush();
947 
948   // Finalize debug and EH information.
949   for (const HandlerInfo &HI : Handlers) {
950     NamedRegionTimer T(HI.TimerName, HI.TimerGroupName,
951                        TimePassesIsEnabled);
952     HI.Handler->endModule();
953     delete HI.Handler;
954   }
955   Handlers.clear();
956   DD = nullptr;
957 
958   // If the target wants to know about weak references, print them all.
959   if (MAI->getWeakRefDirective()) {
960     // FIXME: This is not lazy, it would be nice to only print weak references
961     // to stuff that is actually used.  Note that doing so would require targets
962     // to notice uses in operands (due to constant exprs etc).  This should
963     // happen with the MC stuff eventually.
964 
965     // Print out module-level global variables here.
966     for (const auto &G : M.globals()) {
967       if (!G.hasExternalWeakLinkage())
968         continue;
969       OutStreamer.EmitSymbolAttribute(getSymbol(&G), MCSA_WeakReference);
970     }
971 
972     for (const auto &F : M) {
973       if (!F.hasExternalWeakLinkage())
974         continue;
975       OutStreamer.EmitSymbolAttribute(getSymbol(&F), MCSA_WeakReference);
976     }
977   }
978 
979   if (MAI->hasSetDirective()) {
980     OutStreamer.AddBlankLine();
981     for (const auto &Alias : M.aliases()) {
982       MCSymbol *Name = getSymbol(&Alias);
983 
984       if (Alias.hasExternalLinkage() || !MAI->getWeakRefDirective())
985         OutStreamer.EmitSymbolAttribute(Name, MCSA_Global);
986       else if (Alias.hasWeakLinkage() || Alias.hasLinkOnceLinkage())
987         OutStreamer.EmitSymbolAttribute(Name, MCSA_WeakReference);
988       else
989         assert(Alias.hasLocalLinkage() && "Invalid alias linkage");
990 
991       EmitVisibility(Name, Alias.getVisibility());
992 
993       // Emit the directives as assignments aka .set:
994       OutStreamer.EmitAssignment(Name,
995                                  lowerConstant(Alias.getAliasee(), *this));
996     }
997   }
998 
999   GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
1000   assert(MI && "AsmPrinter didn't require GCModuleInfo?");
1001   for (GCModuleInfo::iterator I = MI->end(), E = MI->begin(); I != E; )
1002     if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(**--I))
1003       MP->finishAssembly(*this);
1004 
1005   // Emit llvm.ident metadata in an '.ident' directive.
1006   EmitModuleIdents(M);
1007 
1008   // If we don't have any trampolines, then we don't require stack memory
1009   // to be executable. Some targets have a directive to declare this.
1010   Function *InitTrampolineIntrinsic = M.getFunction("llvm.init.trampoline");
1011   if (!InitTrampolineIntrinsic || InitTrampolineIntrinsic->use_empty())
1012     if (const MCSection *S = MAI->getNonexecutableStackSection(OutContext))
1013       OutStreamer.SwitchSection(S);
1014 
1015   // Allow the target to emit any magic that it wants at the end of the file,
1016   // after everything else has gone out.
1017   EmitEndOfAsmFile(M);
1018 
1019   delete Mang; Mang = nullptr;
1020   MMI = nullptr;
1021 
1022   OutStreamer.Finish();
1023   OutStreamer.reset();
1024 
1025   return false;
1026 }
1027 
SetupMachineFunction(MachineFunction & MF)1028 void AsmPrinter::SetupMachineFunction(MachineFunction &MF) {
1029   this->MF = &MF;
1030   // Get the function symbol.
1031   CurrentFnSym = getSymbol(MF.getFunction());
1032   CurrentFnSymForSize = CurrentFnSym;
1033 
1034   if (isVerbose())
1035     LI = &getAnalysis<MachineLoopInfo>();
1036 }
1037 
1038 namespace {
1039   // SectionCPs - Keep track the alignment, constpool entries per Section.
1040   struct SectionCPs {
1041     const MCSection *S;
1042     unsigned Alignment;
1043     SmallVector<unsigned, 4> CPEs;
SectionCPs__anon85201b460111::SectionCPs1044     SectionCPs(const MCSection *s, unsigned a) : S(s), Alignment(a) {}
1045   };
1046 }
1047 
1048 /// EmitConstantPool - Print to the current output stream assembly
1049 /// representations of the constants in the constant pool MCP. This is
1050 /// used to print out constants which have been "spilled to memory" by
1051 /// the code generator.
1052 ///
EmitConstantPool()1053 void AsmPrinter::EmitConstantPool() {
1054   const MachineConstantPool *MCP = MF->getConstantPool();
1055   const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
1056   if (CP.empty()) return;
1057 
1058   // Calculate sections for constant pool entries. We collect entries to go into
1059   // the same section together to reduce amount of section switch statements.
1060   SmallVector<SectionCPs, 4> CPSections;
1061   for (unsigned i = 0, e = CP.size(); i != e; ++i) {
1062     const MachineConstantPoolEntry &CPE = CP[i];
1063     unsigned Align = CPE.getAlignment();
1064 
1065     SectionKind Kind;
1066     switch (CPE.getRelocationInfo()) {
1067     default: llvm_unreachable("Unknown section kind");
1068     case 2: Kind = SectionKind::getReadOnlyWithRel(); break;
1069     case 1:
1070       Kind = SectionKind::getReadOnlyWithRelLocal();
1071       break;
1072     case 0:
1073     switch (TM.getDataLayout()->getTypeAllocSize(CPE.getType())) {
1074     case 4:  Kind = SectionKind::getMergeableConst4(); break;
1075     case 8:  Kind = SectionKind::getMergeableConst8(); break;
1076     case 16: Kind = SectionKind::getMergeableConst16();break;
1077     default: Kind = SectionKind::getMergeableConst(); break;
1078     }
1079     }
1080 
1081     const MCSection *S = getObjFileLowering().getSectionForConstant(Kind);
1082 
1083     // The number of sections are small, just do a linear search from the
1084     // last section to the first.
1085     bool Found = false;
1086     unsigned SecIdx = CPSections.size();
1087     while (SecIdx != 0) {
1088       if (CPSections[--SecIdx].S == S) {
1089         Found = true;
1090         break;
1091       }
1092     }
1093     if (!Found) {
1094       SecIdx = CPSections.size();
1095       CPSections.push_back(SectionCPs(S, Align));
1096     }
1097 
1098     if (Align > CPSections[SecIdx].Alignment)
1099       CPSections[SecIdx].Alignment = Align;
1100     CPSections[SecIdx].CPEs.push_back(i);
1101   }
1102 
1103   // Now print stuff into the calculated sections.
1104   for (unsigned i = 0, e = CPSections.size(); i != e; ++i) {
1105     OutStreamer.SwitchSection(CPSections[i].S);
1106     EmitAlignment(Log2_32(CPSections[i].Alignment));
1107 
1108     unsigned Offset = 0;
1109     for (unsigned j = 0, ee = CPSections[i].CPEs.size(); j != ee; ++j) {
1110       unsigned CPI = CPSections[i].CPEs[j];
1111       MachineConstantPoolEntry CPE = CP[CPI];
1112 
1113       // Emit inter-object padding for alignment.
1114       unsigned AlignMask = CPE.getAlignment() - 1;
1115       unsigned NewOffset = (Offset + AlignMask) & ~AlignMask;
1116       OutStreamer.EmitZeros(NewOffset - Offset);
1117 
1118       Type *Ty = CPE.getType();
1119       Offset = NewOffset + TM.getDataLayout()->getTypeAllocSize(Ty);
1120       OutStreamer.EmitLabel(GetCPISymbol(CPI));
1121 
1122       if (CPE.isMachineConstantPoolEntry())
1123         EmitMachineConstantPoolValue(CPE.Val.MachineCPVal);
1124       else
1125         EmitGlobalConstant(CPE.Val.ConstVal);
1126     }
1127   }
1128 }
1129 
1130 /// EmitJumpTableInfo - Print assembly representations of the jump tables used
1131 /// by the current function to the current output stream.
1132 ///
EmitJumpTableInfo()1133 void AsmPrinter::EmitJumpTableInfo() {
1134   const DataLayout *DL = MF->getTarget().getDataLayout();
1135   const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
1136   if (!MJTI) return;
1137   if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
1138   const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
1139   if (JT.empty()) return;
1140 
1141   // Pick the directive to use to print the jump table entries, and switch to
1142   // the appropriate section.
1143   const Function *F = MF->getFunction();
1144   bool JTInDiffSection = false;
1145   if (// In PIC mode, we need to emit the jump table to the same section as the
1146       // function body itself, otherwise the label differences won't make sense.
1147       // FIXME: Need a better predicate for this: what about custom entries?
1148       MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
1149       // We should also do if the section name is NULL or function is declared
1150       // in discardable section
1151       // FIXME: this isn't the right predicate, should be based on the MCSection
1152       // for the function.
1153       F->isWeakForLinker()) {
1154     OutStreamer.SwitchSection(
1155         getObjFileLowering().SectionForGlobal(F, *Mang, TM));
1156   } else {
1157     // Otherwise, drop it in the readonly section.
1158     const MCSection *ReadOnlySection =
1159       getObjFileLowering().getSectionForConstant(SectionKind::getReadOnly());
1160     OutStreamer.SwitchSection(ReadOnlySection);
1161     JTInDiffSection = true;
1162   }
1163 
1164   EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getDataLayout())));
1165 
1166   // Jump tables in code sections are marked with a data_region directive
1167   // where that's supported.
1168   if (!JTInDiffSection)
1169     OutStreamer.EmitDataRegion(MCDR_DataRegionJT32);
1170 
1171   for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
1172     const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
1173 
1174     // If this jump table was deleted, ignore it.
1175     if (JTBBs.empty()) continue;
1176 
1177     // For the EK_LabelDifference32 entry, if the target supports .set, emit a
1178     // .set directive for each unique entry.  This reduces the number of
1179     // relocations the assembler will generate for the jump table.
1180     if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
1181         MAI->hasSetDirective()) {
1182       SmallPtrSet<const MachineBasicBlock*, 16> EmittedSets;
1183       const TargetLowering *TLI = TM.getTargetLowering();
1184       const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF,JTI,OutContext);
1185       for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
1186         const MachineBasicBlock *MBB = JTBBs[ii];
1187         if (!EmittedSets.insert(MBB)) continue;
1188 
1189         // .set LJTSet, LBB32-base
1190         const MCExpr *LHS =
1191           MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
1192         OutStreamer.EmitAssignment(GetJTSetSymbol(JTI, MBB->getNumber()),
1193                                 MCBinaryExpr::CreateSub(LHS, Base, OutContext));
1194       }
1195     }
1196 
1197     // On some targets (e.g. Darwin) we want to emit two consecutive labels
1198     // before each jump table.  The first label is never referenced, but tells
1199     // the assembler and linker the extents of the jump table object.  The
1200     // second label is actually referenced by the code.
1201     if (JTInDiffSection && DL->hasLinkerPrivateGlobalPrefix())
1202       // FIXME: This doesn't have to have any specific name, just any randomly
1203       // named and numbered 'l' label would work.  Simplify GetJTISymbol.
1204       OutStreamer.EmitLabel(GetJTISymbol(JTI, true));
1205 
1206     OutStreamer.EmitLabel(GetJTISymbol(JTI));
1207 
1208     for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
1209       EmitJumpTableEntry(MJTI, JTBBs[ii], JTI);
1210   }
1211   if (!JTInDiffSection)
1212     OutStreamer.EmitDataRegion(MCDR_DataRegionEnd);
1213 }
1214 
1215 /// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the
1216 /// current stream.
EmitJumpTableEntry(const MachineJumpTableInfo * MJTI,const MachineBasicBlock * MBB,unsigned UID) const1217 void AsmPrinter::EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
1218                                     const MachineBasicBlock *MBB,
1219                                     unsigned UID) const {
1220   assert(MBB && MBB->getNumber() >= 0 && "Invalid basic block");
1221   const MCExpr *Value = nullptr;
1222   switch (MJTI->getEntryKind()) {
1223   case MachineJumpTableInfo::EK_Inline:
1224     llvm_unreachable("Cannot emit EK_Inline jump table entry");
1225   case MachineJumpTableInfo::EK_Custom32:
1226     Value = TM.getTargetLowering()->LowerCustomJumpTableEntry(MJTI, MBB, UID,
1227                                                               OutContext);
1228     break;
1229   case MachineJumpTableInfo::EK_BlockAddress:
1230     // EK_BlockAddress - Each entry is a plain address of block, e.g.:
1231     //     .word LBB123
1232     Value = MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
1233     break;
1234   case MachineJumpTableInfo::EK_GPRel32BlockAddress: {
1235     // EK_GPRel32BlockAddress - Each entry is an address of block, encoded
1236     // with a relocation as gp-relative, e.g.:
1237     //     .gprel32 LBB123
1238     MCSymbol *MBBSym = MBB->getSymbol();
1239     OutStreamer.EmitGPRel32Value(MCSymbolRefExpr::Create(MBBSym, OutContext));
1240     return;
1241   }
1242 
1243   case MachineJumpTableInfo::EK_GPRel64BlockAddress: {
1244     // EK_GPRel64BlockAddress - Each entry is an address of block, encoded
1245     // with a relocation as gp-relative, e.g.:
1246     //     .gpdword LBB123
1247     MCSymbol *MBBSym = MBB->getSymbol();
1248     OutStreamer.EmitGPRel64Value(MCSymbolRefExpr::Create(MBBSym, OutContext));
1249     return;
1250   }
1251 
1252   case MachineJumpTableInfo::EK_LabelDifference32: {
1253     // EK_LabelDifference32 - Each entry is the address of the block minus
1254     // the address of the jump table.  This is used for PIC jump tables where
1255     // gprel32 is not supported.  e.g.:
1256     //      .word LBB123 - LJTI1_2
1257     // If the .set directive is supported, this is emitted as:
1258     //      .set L4_5_set_123, LBB123 - LJTI1_2
1259     //      .word L4_5_set_123
1260 
1261     // If we have emitted set directives for the jump table entries, print
1262     // them rather than the entries themselves.  If we're emitting PIC, then
1263     // emit the table entries as differences between two text section labels.
1264     if (MAI->hasSetDirective()) {
1265       // If we used .set, reference the .set's symbol.
1266       Value = MCSymbolRefExpr::Create(GetJTSetSymbol(UID, MBB->getNumber()),
1267                                       OutContext);
1268       break;
1269     }
1270     // Otherwise, use the difference as the jump table entry.
1271     Value = MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
1272     const MCExpr *JTI = MCSymbolRefExpr::Create(GetJTISymbol(UID), OutContext);
1273     Value = MCBinaryExpr::CreateSub(Value, JTI, OutContext);
1274     break;
1275   }
1276   }
1277 
1278   assert(Value && "Unknown entry kind!");
1279 
1280   unsigned EntrySize = MJTI->getEntrySize(*TM.getDataLayout());
1281   OutStreamer.EmitValue(Value, EntrySize);
1282 }
1283 
1284 
1285 /// EmitSpecialLLVMGlobal - Check to see if the specified global is a
1286 /// special global used by LLVM.  If so, emit it and return true, otherwise
1287 /// do nothing and return false.
EmitSpecialLLVMGlobal(const GlobalVariable * GV)1288 bool AsmPrinter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
1289   if (GV->getName() == "llvm.used") {
1290     if (MAI->hasNoDeadStrip())    // No need to emit this at all.
1291       EmitLLVMUsedList(cast<ConstantArray>(GV->getInitializer()));
1292     return true;
1293   }
1294 
1295   // Ignore debug and non-emitted data.  This handles llvm.compiler.used.
1296   if (StringRef(GV->getSection()) == "llvm.metadata" ||
1297       GV->hasAvailableExternallyLinkage())
1298     return true;
1299 
1300   if (!GV->hasAppendingLinkage()) return false;
1301 
1302   assert(GV->hasInitializer() && "Not a special LLVM global!");
1303 
1304   if (GV->getName() == "llvm.global_ctors") {
1305     EmitXXStructorList(GV->getInitializer(), /* isCtor */ true);
1306 
1307     if (TM.getRelocationModel() == Reloc::Static &&
1308         MAI->hasStaticCtorDtorReferenceInStaticMode()) {
1309       StringRef Sym(".constructors_used");
1310       OutStreamer.EmitSymbolAttribute(OutContext.GetOrCreateSymbol(Sym),
1311                                       MCSA_Reference);
1312     }
1313     return true;
1314   }
1315 
1316   if (GV->getName() == "llvm.global_dtors") {
1317     EmitXXStructorList(GV->getInitializer(), /* isCtor */ false);
1318 
1319     if (TM.getRelocationModel() == Reloc::Static &&
1320         MAI->hasStaticCtorDtorReferenceInStaticMode()) {
1321       StringRef Sym(".destructors_used");
1322       OutStreamer.EmitSymbolAttribute(OutContext.GetOrCreateSymbol(Sym),
1323                                       MCSA_Reference);
1324     }
1325     return true;
1326   }
1327 
1328   return false;
1329 }
1330 
1331 /// EmitLLVMUsedList - For targets that define a MAI::UsedDirective, mark each
1332 /// global in the specified llvm.used list for which emitUsedDirectiveFor
1333 /// is true, as being used with this directive.
EmitLLVMUsedList(const ConstantArray * InitList)1334 void AsmPrinter::EmitLLVMUsedList(const ConstantArray *InitList) {
1335   // Should be an array of 'i8*'.
1336   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
1337     const GlobalValue *GV =
1338       dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
1339     if (GV)
1340       OutStreamer.EmitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip);
1341   }
1342 }
1343 
1344 namespace {
1345 struct Structor {
Structor__anon85201b460211::Structor1346   Structor() : Priority(0), Func(nullptr), ComdatKey(nullptr) {}
1347   int Priority;
1348   llvm::Constant *Func;
1349   llvm::GlobalValue *ComdatKey;
1350 };
1351 } // end namespace
1352 
1353 /// EmitXXStructorList - Emit the ctor or dtor list taking into account the init
1354 /// priority.
EmitXXStructorList(const Constant * List,bool isCtor)1355 void AsmPrinter::EmitXXStructorList(const Constant *List, bool isCtor) {
1356   // Should be an array of '{ int, void ()* }' structs.  The first value is the
1357   // init priority.
1358   if (!isa<ConstantArray>(List)) return;
1359 
1360   // Sanity check the structors list.
1361   const ConstantArray *InitList = dyn_cast<ConstantArray>(List);
1362   if (!InitList) return; // Not an array!
1363   StructType *ETy = dyn_cast<StructType>(InitList->getType()->getElementType());
1364   // FIXME: Only allow the 3-field form in LLVM 4.0.
1365   if (!ETy || ETy->getNumElements() < 2 || ETy->getNumElements() > 3)
1366     return; // Not an array of two or three elements!
1367   if (!isa<IntegerType>(ETy->getTypeAtIndex(0U)) ||
1368       !isa<PointerType>(ETy->getTypeAtIndex(1U))) return; // Not (int, ptr).
1369   if (ETy->getNumElements() == 3 && !isa<PointerType>(ETy->getTypeAtIndex(2U)))
1370     return; // Not (int, ptr, ptr).
1371 
1372   // Gather the structors in a form that's convenient for sorting by priority.
1373   SmallVector<Structor, 8> Structors;
1374   for (Value *O : InitList->operands()) {
1375     ConstantStruct *CS = dyn_cast<ConstantStruct>(O);
1376     if (!CS) continue; // Malformed.
1377     if (CS->getOperand(1)->isNullValue())
1378       break;  // Found a null terminator, skip the rest.
1379     ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1380     if (!Priority) continue; // Malformed.
1381     Structors.push_back(Structor());
1382     Structor &S = Structors.back();
1383     S.Priority = Priority->getLimitedValue(65535);
1384     S.Func = CS->getOperand(1);
1385     if (ETy->getNumElements() == 3 && !CS->getOperand(2)->isNullValue())
1386       S.ComdatKey = dyn_cast<GlobalValue>(CS->getOperand(2)->stripPointerCasts());
1387   }
1388 
1389   // Emit the function pointers in the target-specific order
1390   const DataLayout *DL = TM.getDataLayout();
1391   unsigned Align = Log2_32(DL->getPointerPrefAlignment());
1392   std::stable_sort(Structors.begin(), Structors.end(),
1393                    [](const Structor &L,
1394                       const Structor &R) { return L.Priority < R.Priority; });
1395   for (Structor &S : Structors) {
1396     const TargetLoweringObjectFile &Obj = getObjFileLowering();
1397     const MCSymbol *KeySym = nullptr;
1398     if (GlobalValue *GV = S.ComdatKey) {
1399       if (GV->hasAvailableExternallyLinkage())
1400         // If the associated variable is available_externally, some other TU
1401         // will provide its dynamic initializer.
1402         continue;
1403 
1404       KeySym = getSymbol(GV);
1405     }
1406     const MCSection *OutputSection =
1407         (isCtor ? Obj.getStaticCtorSection(S.Priority, KeySym)
1408                 : Obj.getStaticDtorSection(S.Priority, KeySym));
1409     OutStreamer.SwitchSection(OutputSection);
1410     if (OutStreamer.getCurrentSection() != OutStreamer.getPreviousSection())
1411       EmitAlignment(Align);
1412     EmitXXStructor(S.Func);
1413   }
1414 }
1415 
EmitModuleIdents(Module & M)1416 void AsmPrinter::EmitModuleIdents(Module &M) {
1417   if (!MAI->hasIdentDirective())
1418     return;
1419 
1420   if (const NamedMDNode *NMD = M.getNamedMetadata("llvm.ident")) {
1421     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
1422       const MDNode *N = NMD->getOperand(i);
1423       assert(N->getNumOperands() == 1 &&
1424              "llvm.ident metadata entry can have only one operand");
1425       const MDString *S = cast<MDString>(N->getOperand(0));
1426       OutStreamer.EmitIdent(S->getString());
1427     }
1428   }
1429 }
1430 
1431 //===--------------------------------------------------------------------===//
1432 // Emission and print routines
1433 //
1434 
1435 /// EmitInt8 - Emit a byte directive and value.
1436 ///
EmitInt8(int Value) const1437 void AsmPrinter::EmitInt8(int Value) const {
1438   OutStreamer.EmitIntValue(Value, 1);
1439 }
1440 
1441 /// EmitInt16 - Emit a short directive and value.
1442 ///
EmitInt16(int Value) const1443 void AsmPrinter::EmitInt16(int Value) const {
1444   OutStreamer.EmitIntValue(Value, 2);
1445 }
1446 
1447 /// EmitInt32 - Emit a long directive and value.
1448 ///
EmitInt32(int Value) const1449 void AsmPrinter::EmitInt32(int Value) const {
1450   OutStreamer.EmitIntValue(Value, 4);
1451 }
1452 
1453 /// EmitLabelDifference - Emit something like ".long Hi-Lo" where the size
1454 /// in bytes of the directive is specified by Size and Hi/Lo specify the
1455 /// labels.  This implicitly uses .set if it is available.
EmitLabelDifference(const MCSymbol * Hi,const MCSymbol * Lo,unsigned Size) const1456 void AsmPrinter::EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
1457                                      unsigned Size) const {
1458   // Get the Hi-Lo expression.
1459   const MCExpr *Diff =
1460     MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create(Hi, OutContext),
1461                             MCSymbolRefExpr::Create(Lo, OutContext),
1462                             OutContext);
1463 
1464   if (!MAI->hasSetDirective()) {
1465     OutStreamer.EmitValue(Diff, Size);
1466     return;
1467   }
1468 
1469   // Otherwise, emit with .set (aka assignment).
1470   MCSymbol *SetLabel = GetTempSymbol("set", SetCounter++);
1471   OutStreamer.EmitAssignment(SetLabel, Diff);
1472   OutStreamer.EmitSymbolValue(SetLabel, Size);
1473 }
1474 
1475 /// EmitLabelOffsetDifference - Emit something like ".long Hi+Offset-Lo"
1476 /// where the size in bytes of the directive is specified by Size and Hi/Lo
1477 /// specify the labels.  This implicitly uses .set if it is available.
EmitLabelOffsetDifference(const MCSymbol * Hi,uint64_t Offset,const MCSymbol * Lo,unsigned Size) const1478 void AsmPrinter::EmitLabelOffsetDifference(const MCSymbol *Hi, uint64_t Offset,
1479                                            const MCSymbol *Lo,
1480                                            unsigned Size) const {
1481 
1482   // Emit Hi+Offset - Lo
1483   // Get the Hi+Offset expression.
1484   const MCExpr *Plus =
1485     MCBinaryExpr::CreateAdd(MCSymbolRefExpr::Create(Hi, OutContext),
1486                             MCConstantExpr::Create(Offset, OutContext),
1487                             OutContext);
1488 
1489   // Get the Hi+Offset-Lo expression.
1490   const MCExpr *Diff =
1491     MCBinaryExpr::CreateSub(Plus,
1492                             MCSymbolRefExpr::Create(Lo, OutContext),
1493                             OutContext);
1494 
1495   if (!MAI->hasSetDirective())
1496     OutStreamer.EmitValue(Diff, Size);
1497   else {
1498     // Otherwise, emit with .set (aka assignment).
1499     MCSymbol *SetLabel = GetTempSymbol("set", SetCounter++);
1500     OutStreamer.EmitAssignment(SetLabel, Diff);
1501     OutStreamer.EmitSymbolValue(SetLabel, Size);
1502   }
1503 }
1504 
1505 /// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
1506 /// where the size in bytes of the directive is specified by Size and Label
1507 /// specifies the label.  This implicitly uses .set if it is available.
EmitLabelPlusOffset(const MCSymbol * Label,uint64_t Offset,unsigned Size,bool IsSectionRelative) const1508 void AsmPrinter::EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
1509                                      unsigned Size,
1510                                      bool IsSectionRelative) const {
1511   if (MAI->needsDwarfSectionOffsetDirective() && IsSectionRelative) {
1512     OutStreamer.EmitCOFFSecRel32(Label);
1513     return;
1514   }
1515 
1516   // Emit Label+Offset (or just Label if Offset is zero)
1517   const MCExpr *Expr = MCSymbolRefExpr::Create(Label, OutContext);
1518   if (Offset)
1519     Expr = MCBinaryExpr::CreateAdd(
1520         Expr, MCConstantExpr::Create(Offset, OutContext), OutContext);
1521 
1522   OutStreamer.EmitValue(Expr, Size);
1523 }
1524 
1525 //===----------------------------------------------------------------------===//
1526 
1527 // EmitAlignment - Emit an alignment directive to the specified power of
1528 // two boundary.  For example, if you pass in 3 here, you will get an 8
1529 // byte alignment.  If a global value is specified, and if that global has
1530 // an explicit alignment requested, it will override the alignment request
1531 // if required for correctness.
1532 //
EmitAlignment(unsigned NumBits,const GlobalObject * GV) const1533 void AsmPrinter::EmitAlignment(unsigned NumBits, const GlobalObject *GV) const {
1534   if (GV) NumBits = getGVAlignmentLog2(GV, *TM.getDataLayout(), NumBits);
1535 
1536   if (NumBits == 0) return;   // 1-byte aligned: no need to emit alignment.
1537 
1538   if (getCurrentSection()->getKind().isText())
1539     OutStreamer.EmitCodeAlignment(1 << NumBits);
1540   else
1541     OutStreamer.EmitValueToAlignment(1 << NumBits);
1542 }
1543 
1544 //===----------------------------------------------------------------------===//
1545 // Constant emission.
1546 //===----------------------------------------------------------------------===//
1547 
1548 /// lowerConstant - Lower the specified LLVM Constant to an MCExpr.
1549 ///
lowerConstant(const Constant * CV,AsmPrinter & AP)1550 static const MCExpr *lowerConstant(const Constant *CV, AsmPrinter &AP) {
1551   MCContext &Ctx = AP.OutContext;
1552 
1553   if (CV->isNullValue() || isa<UndefValue>(CV))
1554     return MCConstantExpr::Create(0, Ctx);
1555 
1556   if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV))
1557     return MCConstantExpr::Create(CI->getZExtValue(), Ctx);
1558 
1559   if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
1560     return MCSymbolRefExpr::Create(AP.getSymbol(GV), Ctx);
1561 
1562   if (const BlockAddress *BA = dyn_cast<BlockAddress>(CV))
1563     return MCSymbolRefExpr::Create(AP.GetBlockAddressSymbol(BA), Ctx);
1564 
1565   const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
1566   if (!CE) {
1567     llvm_unreachable("Unknown constant value to lower!");
1568   }
1569 
1570   if (const MCExpr *RelocExpr =
1571           AP.getObjFileLowering().getExecutableRelativeSymbol(CE, *AP.Mang,
1572                                                               AP.TM))
1573     return RelocExpr;
1574 
1575   switch (CE->getOpcode()) {
1576   default:
1577     // If the code isn't optimized, there may be outstanding folding
1578     // opportunities. Attempt to fold the expression using DataLayout as a
1579     // last resort before giving up.
1580     if (Constant *C =
1581           ConstantFoldConstantExpression(CE, AP.TM.getDataLayout()))
1582       if (C != CE)
1583         return lowerConstant(C, AP);
1584 
1585     // Otherwise report the problem to the user.
1586     {
1587       std::string S;
1588       raw_string_ostream OS(S);
1589       OS << "Unsupported expression in static initializer: ";
1590       CE->printAsOperand(OS, /*PrintType=*/false,
1591                      !AP.MF ? nullptr : AP.MF->getFunction()->getParent());
1592       report_fatal_error(OS.str());
1593     }
1594   case Instruction::GetElementPtr: {
1595     const DataLayout &DL = *AP.TM.getDataLayout();
1596     // Generate a symbolic expression for the byte address
1597     APInt OffsetAI(DL.getPointerTypeSizeInBits(CE->getType()), 0);
1598     cast<GEPOperator>(CE)->accumulateConstantOffset(DL, OffsetAI);
1599 
1600     const MCExpr *Base = lowerConstant(CE->getOperand(0), AP);
1601     if (!OffsetAI)
1602       return Base;
1603 
1604     int64_t Offset = OffsetAI.getSExtValue();
1605     return MCBinaryExpr::CreateAdd(Base, MCConstantExpr::Create(Offset, Ctx),
1606                                    Ctx);
1607   }
1608 
1609   case Instruction::Trunc:
1610     // We emit the value and depend on the assembler to truncate the generated
1611     // expression properly.  This is important for differences between
1612     // blockaddress labels.  Since the two labels are in the same function, it
1613     // is reasonable to treat their delta as a 32-bit value.
1614     // FALL THROUGH.
1615   case Instruction::BitCast:
1616     return lowerConstant(CE->getOperand(0), AP);
1617 
1618   case Instruction::IntToPtr: {
1619     const DataLayout &DL = *AP.TM.getDataLayout();
1620     // Handle casts to pointers by changing them into casts to the appropriate
1621     // integer type.  This promotes constant folding and simplifies this code.
1622     Constant *Op = CE->getOperand(0);
1623     Op = ConstantExpr::getIntegerCast(Op, DL.getIntPtrType(CV->getType()),
1624                                       false/*ZExt*/);
1625     return lowerConstant(Op, AP);
1626   }
1627 
1628   case Instruction::PtrToInt: {
1629     const DataLayout &DL = *AP.TM.getDataLayout();
1630     // Support only foldable casts to/from pointers that can be eliminated by
1631     // changing the pointer to the appropriately sized integer type.
1632     Constant *Op = CE->getOperand(0);
1633     Type *Ty = CE->getType();
1634 
1635     const MCExpr *OpExpr = lowerConstant(Op, AP);
1636 
1637     // We can emit the pointer value into this slot if the slot is an
1638     // integer slot equal to the size of the pointer.
1639     if (DL.getTypeAllocSize(Ty) == DL.getTypeAllocSize(Op->getType()))
1640       return OpExpr;
1641 
1642     // Otherwise the pointer is smaller than the resultant integer, mask off
1643     // the high bits so we are sure to get a proper truncation if the input is
1644     // a constant expr.
1645     unsigned InBits = DL.getTypeAllocSizeInBits(Op->getType());
1646     const MCExpr *MaskExpr = MCConstantExpr::Create(~0ULL >> (64-InBits), Ctx);
1647     return MCBinaryExpr::CreateAnd(OpExpr, MaskExpr, Ctx);
1648   }
1649 
1650   // The MC library also has a right-shift operator, but it isn't consistently
1651   // signed or unsigned between different targets.
1652   case Instruction::Add:
1653   case Instruction::Sub:
1654   case Instruction::Mul:
1655   case Instruction::SDiv:
1656   case Instruction::SRem:
1657   case Instruction::Shl:
1658   case Instruction::And:
1659   case Instruction::Or:
1660   case Instruction::Xor: {
1661     const MCExpr *LHS = lowerConstant(CE->getOperand(0), AP);
1662     const MCExpr *RHS = lowerConstant(CE->getOperand(1), AP);
1663     switch (CE->getOpcode()) {
1664     default: llvm_unreachable("Unknown binary operator constant cast expr");
1665     case Instruction::Add: return MCBinaryExpr::CreateAdd(LHS, RHS, Ctx);
1666     case Instruction::Sub: return MCBinaryExpr::CreateSub(LHS, RHS, Ctx);
1667     case Instruction::Mul: return MCBinaryExpr::CreateMul(LHS, RHS, Ctx);
1668     case Instruction::SDiv: return MCBinaryExpr::CreateDiv(LHS, RHS, Ctx);
1669     case Instruction::SRem: return MCBinaryExpr::CreateMod(LHS, RHS, Ctx);
1670     case Instruction::Shl: return MCBinaryExpr::CreateShl(LHS, RHS, Ctx);
1671     case Instruction::And: return MCBinaryExpr::CreateAnd(LHS, RHS, Ctx);
1672     case Instruction::Or:  return MCBinaryExpr::CreateOr (LHS, RHS, Ctx);
1673     case Instruction::Xor: return MCBinaryExpr::CreateXor(LHS, RHS, Ctx);
1674     }
1675   }
1676   }
1677 }
1678 
1679 static void emitGlobalConstantImpl(const Constant *C, AsmPrinter &AP);
1680 
1681 /// isRepeatedByteSequence - Determine whether the given value is
1682 /// composed of a repeated sequence of identical bytes and return the
1683 /// byte value.  If it is not a repeated sequence, return -1.
isRepeatedByteSequence(const ConstantDataSequential * V)1684 static int isRepeatedByteSequence(const ConstantDataSequential *V) {
1685   StringRef Data = V->getRawDataValues();
1686   assert(!Data.empty() && "Empty aggregates should be CAZ node");
1687   char C = Data[0];
1688   for (unsigned i = 1, e = Data.size(); i != e; ++i)
1689     if (Data[i] != C) return -1;
1690   return static_cast<uint8_t>(C); // Ensure 255 is not returned as -1.
1691 }
1692 
1693 
1694 /// isRepeatedByteSequence - Determine whether the given value is
1695 /// composed of a repeated sequence of identical bytes and return the
1696 /// byte value.  If it is not a repeated sequence, return -1.
isRepeatedByteSequence(const Value * V,TargetMachine & TM)1697 static int isRepeatedByteSequence(const Value *V, TargetMachine &TM) {
1698 
1699   if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
1700     if (CI->getBitWidth() > 64) return -1;
1701 
1702     uint64_t Size = TM.getDataLayout()->getTypeAllocSize(V->getType());
1703     uint64_t Value = CI->getZExtValue();
1704 
1705     // Make sure the constant is at least 8 bits long and has a power
1706     // of 2 bit width.  This guarantees the constant bit width is
1707     // always a multiple of 8 bits, avoiding issues with padding out
1708     // to Size and other such corner cases.
1709     if (CI->getBitWidth() < 8 || !isPowerOf2_64(CI->getBitWidth())) return -1;
1710 
1711     uint8_t Byte = static_cast<uint8_t>(Value);
1712 
1713     for (unsigned i = 1; i < Size; ++i) {
1714       Value >>= 8;
1715       if (static_cast<uint8_t>(Value) != Byte) return -1;
1716     }
1717     return Byte;
1718   }
1719   if (const ConstantArray *CA = dyn_cast<ConstantArray>(V)) {
1720     // Make sure all array elements are sequences of the same repeated
1721     // byte.
1722     assert(CA->getNumOperands() != 0 && "Should be a CAZ");
1723     int Byte = isRepeatedByteSequence(CA->getOperand(0), TM);
1724     if (Byte == -1) return -1;
1725 
1726     for (unsigned i = 1, e = CA->getNumOperands(); i != e; ++i) {
1727       int ThisByte = isRepeatedByteSequence(CA->getOperand(i), TM);
1728       if (ThisByte == -1) return -1;
1729       if (Byte != ThisByte) return -1;
1730     }
1731     return Byte;
1732   }
1733 
1734   if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(V))
1735     return isRepeatedByteSequence(CDS);
1736 
1737   return -1;
1738 }
1739 
emitGlobalConstantDataSequential(const ConstantDataSequential * CDS,AsmPrinter & AP)1740 static void emitGlobalConstantDataSequential(const ConstantDataSequential *CDS,
1741                                              AsmPrinter &AP){
1742 
1743   // See if we can aggregate this into a .fill, if so, emit it as such.
1744   int Value = isRepeatedByteSequence(CDS, AP.TM);
1745   if (Value != -1) {
1746     uint64_t Bytes = AP.TM.getDataLayout()->getTypeAllocSize(CDS->getType());
1747     // Don't emit a 1-byte object as a .fill.
1748     if (Bytes > 1)
1749       return AP.OutStreamer.EmitFill(Bytes, Value);
1750   }
1751 
1752   // If this can be emitted with .ascii/.asciz, emit it as such.
1753   if (CDS->isString())
1754     return AP.OutStreamer.EmitBytes(CDS->getAsString());
1755 
1756   // Otherwise, emit the values in successive locations.
1757   unsigned ElementByteSize = CDS->getElementByteSize();
1758   if (isa<IntegerType>(CDS->getElementType())) {
1759     for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1760       if (AP.isVerbose())
1761         AP.OutStreamer.GetCommentOS() << format("0x%" PRIx64 "\n",
1762                                                 CDS->getElementAsInteger(i));
1763       AP.OutStreamer.EmitIntValue(CDS->getElementAsInteger(i),
1764                                   ElementByteSize);
1765     }
1766   } else if (ElementByteSize == 4) {
1767     // FP Constants are printed as integer constants to avoid losing
1768     // precision.
1769     assert(CDS->getElementType()->isFloatTy());
1770     for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1771       union {
1772         float F;
1773         uint32_t I;
1774       };
1775 
1776       F = CDS->getElementAsFloat(i);
1777       if (AP.isVerbose())
1778         AP.OutStreamer.GetCommentOS() << "float " << F << '\n';
1779       AP.OutStreamer.EmitIntValue(I, 4);
1780     }
1781   } else {
1782     assert(CDS->getElementType()->isDoubleTy());
1783     for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
1784       union {
1785         double F;
1786         uint64_t I;
1787       };
1788 
1789       F = CDS->getElementAsDouble(i);
1790       if (AP.isVerbose())
1791         AP.OutStreamer.GetCommentOS() << "double " << F << '\n';
1792       AP.OutStreamer.EmitIntValue(I, 8);
1793     }
1794   }
1795 
1796   const DataLayout &DL = *AP.TM.getDataLayout();
1797   unsigned Size = DL.getTypeAllocSize(CDS->getType());
1798   unsigned EmittedSize = DL.getTypeAllocSize(CDS->getType()->getElementType()) *
1799                         CDS->getNumElements();
1800   if (unsigned Padding = Size - EmittedSize)
1801     AP.OutStreamer.EmitZeros(Padding);
1802 
1803 }
1804 
emitGlobalConstantArray(const ConstantArray * CA,AsmPrinter & AP)1805 static void emitGlobalConstantArray(const ConstantArray *CA, AsmPrinter &AP) {
1806   // See if we can aggregate some values.  Make sure it can be
1807   // represented as a series of bytes of the constant value.
1808   int Value = isRepeatedByteSequence(CA, AP.TM);
1809 
1810   if (Value != -1) {
1811     uint64_t Bytes = AP.TM.getDataLayout()->getTypeAllocSize(CA->getType());
1812     AP.OutStreamer.EmitFill(Bytes, Value);
1813   }
1814   else {
1815     for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
1816       emitGlobalConstantImpl(CA->getOperand(i), AP);
1817   }
1818 }
1819 
emitGlobalConstantVector(const ConstantVector * CV,AsmPrinter & AP)1820 static void emitGlobalConstantVector(const ConstantVector *CV, AsmPrinter &AP) {
1821   for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
1822     emitGlobalConstantImpl(CV->getOperand(i), AP);
1823 
1824   const DataLayout &DL = *AP.TM.getDataLayout();
1825   unsigned Size = DL.getTypeAllocSize(CV->getType());
1826   unsigned EmittedSize = DL.getTypeAllocSize(CV->getType()->getElementType()) *
1827                          CV->getType()->getNumElements();
1828   if (unsigned Padding = Size - EmittedSize)
1829     AP.OutStreamer.EmitZeros(Padding);
1830 }
1831 
emitGlobalConstantStruct(const ConstantStruct * CS,AsmPrinter & AP)1832 static void emitGlobalConstantStruct(const ConstantStruct *CS, AsmPrinter &AP) {
1833   // Print the fields in successive locations. Pad to align if needed!
1834   const DataLayout *DL = AP.TM.getDataLayout();
1835   unsigned Size = DL->getTypeAllocSize(CS->getType());
1836   const StructLayout *Layout = DL->getStructLayout(CS->getType());
1837   uint64_t SizeSoFar = 0;
1838   for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
1839     const Constant *Field = CS->getOperand(i);
1840 
1841     // Check if padding is needed and insert one or more 0s.
1842     uint64_t FieldSize = DL->getTypeAllocSize(Field->getType());
1843     uint64_t PadSize = ((i == e-1 ? Size : Layout->getElementOffset(i+1))
1844                         - Layout->getElementOffset(i)) - FieldSize;
1845     SizeSoFar += FieldSize + PadSize;
1846 
1847     // Now print the actual field value.
1848     emitGlobalConstantImpl(Field, AP);
1849 
1850     // Insert padding - this may include padding to increase the size of the
1851     // current field up to the ABI size (if the struct is not packed) as well
1852     // as padding to ensure that the next field starts at the right offset.
1853     AP.OutStreamer.EmitZeros(PadSize);
1854   }
1855   assert(SizeSoFar == Layout->getSizeInBytes() &&
1856          "Layout of constant struct may be incorrect!");
1857 }
1858 
emitGlobalConstantFP(const ConstantFP * CFP,AsmPrinter & AP)1859 static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP) {
1860   APInt API = CFP->getValueAPF().bitcastToAPInt();
1861 
1862   // First print a comment with what we think the original floating-point value
1863   // should have been.
1864   if (AP.isVerbose()) {
1865     SmallString<8> StrVal;
1866     CFP->getValueAPF().toString(StrVal);
1867 
1868     if (CFP->getType())
1869       CFP->getType()->print(AP.OutStreamer.GetCommentOS());
1870     else
1871       AP.OutStreamer.GetCommentOS() << "Printing <null> Type";
1872     AP.OutStreamer.GetCommentOS() << ' ' << StrVal << '\n';
1873   }
1874 
1875   // Now iterate through the APInt chunks, emitting them in endian-correct
1876   // order, possibly with a smaller chunk at beginning/end (e.g. for x87 80-bit
1877   // floats).
1878   unsigned NumBytes = API.getBitWidth() / 8;
1879   unsigned TrailingBytes = NumBytes % sizeof(uint64_t);
1880   const uint64_t *p = API.getRawData();
1881 
1882   // PPC's long double has odd notions of endianness compared to how LLVM
1883   // handles it: p[0] goes first for *big* endian on PPC.
1884   if (AP.TM.getDataLayout()->isBigEndian() &&
1885       !CFP->getType()->isPPC_FP128Ty()) {
1886     int Chunk = API.getNumWords() - 1;
1887 
1888     if (TrailingBytes)
1889       AP.OutStreamer.EmitIntValue(p[Chunk--], TrailingBytes);
1890 
1891     for (; Chunk >= 0; --Chunk)
1892       AP.OutStreamer.EmitIntValue(p[Chunk], sizeof(uint64_t));
1893   } else {
1894     unsigned Chunk;
1895     for (Chunk = 0; Chunk < NumBytes / sizeof(uint64_t); ++Chunk)
1896       AP.OutStreamer.EmitIntValue(p[Chunk], sizeof(uint64_t));
1897 
1898     if (TrailingBytes)
1899       AP.OutStreamer.EmitIntValue(p[Chunk], TrailingBytes);
1900   }
1901 
1902   // Emit the tail padding for the long double.
1903   const DataLayout &DL = *AP.TM.getDataLayout();
1904   AP.OutStreamer.EmitZeros(DL.getTypeAllocSize(CFP->getType()) -
1905                            DL.getTypeStoreSize(CFP->getType()));
1906 }
1907 
emitGlobalConstantLargeInt(const ConstantInt * CI,AsmPrinter & AP)1908 static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP) {
1909   const DataLayout *DL = AP.TM.getDataLayout();
1910   unsigned BitWidth = CI->getBitWidth();
1911 
1912   // Copy the value as we may massage the layout for constants whose bit width
1913   // is not a multiple of 64-bits.
1914   APInt Realigned(CI->getValue());
1915   uint64_t ExtraBits = 0;
1916   unsigned ExtraBitsSize = BitWidth & 63;
1917 
1918   if (ExtraBitsSize) {
1919     // The bit width of the data is not a multiple of 64-bits.
1920     // The extra bits are expected to be at the end of the chunk of the memory.
1921     // Little endian:
1922     // * Nothing to be done, just record the extra bits to emit.
1923     // Big endian:
1924     // * Record the extra bits to emit.
1925     // * Realign the raw data to emit the chunks of 64-bits.
1926     if (DL->isBigEndian()) {
1927       // Basically the structure of the raw data is a chunk of 64-bits cells:
1928       //    0        1         BitWidth / 64
1929       // [chunk1][chunk2] ... [chunkN].
1930       // The most significant chunk is chunkN and it should be emitted first.
1931       // However, due to the alignment issue chunkN contains useless bits.
1932       // Realign the chunks so that they contain only useless information:
1933       // ExtraBits     0       1       (BitWidth / 64) - 1
1934       //       chu[nk1 chu][nk2 chu] ... [nkN-1 chunkN]
1935       ExtraBits = Realigned.getRawData()[0] &
1936         (((uint64_t)-1) >> (64 - ExtraBitsSize));
1937       Realigned = Realigned.lshr(ExtraBitsSize);
1938     } else
1939       ExtraBits = Realigned.getRawData()[BitWidth / 64];
1940   }
1941 
1942   // We don't expect assemblers to support integer data directives
1943   // for more than 64 bits, so we emit the data in at most 64-bit
1944   // quantities at a time.
1945   const uint64_t *RawData = Realigned.getRawData();
1946   for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
1947     uint64_t Val = DL->isBigEndian() ? RawData[e - i - 1] : RawData[i];
1948     AP.OutStreamer.EmitIntValue(Val, 8);
1949   }
1950 
1951   if (ExtraBitsSize) {
1952     // Emit the extra bits after the 64-bits chunks.
1953 
1954     // Emit a directive that fills the expected size.
1955     uint64_t Size = AP.TM.getDataLayout()->getTypeAllocSize(CI->getType());
1956     Size -= (BitWidth / 64) * 8;
1957     assert(Size && Size * 8 >= ExtraBitsSize &&
1958            (ExtraBits & (((uint64_t)-1) >> (64 - ExtraBitsSize)))
1959            == ExtraBits && "Directive too small for extra bits.");
1960     AP.OutStreamer.EmitIntValue(ExtraBits, Size);
1961   }
1962 }
1963 
emitGlobalConstantImpl(const Constant * CV,AsmPrinter & AP)1964 static void emitGlobalConstantImpl(const Constant *CV, AsmPrinter &AP) {
1965   const DataLayout *DL = AP.TM.getDataLayout();
1966   uint64_t Size = DL->getTypeAllocSize(CV->getType());
1967   if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
1968     return AP.OutStreamer.EmitZeros(Size);
1969 
1970   if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
1971     switch (Size) {
1972     case 1:
1973     case 2:
1974     case 4:
1975     case 8:
1976       if (AP.isVerbose())
1977         AP.OutStreamer.GetCommentOS() << format("0x%" PRIx64 "\n",
1978                                                 CI->getZExtValue());
1979       AP.OutStreamer.EmitIntValue(CI->getZExtValue(), Size);
1980       return;
1981     default:
1982       emitGlobalConstantLargeInt(CI, AP);
1983       return;
1984     }
1985   }
1986 
1987   if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV))
1988     return emitGlobalConstantFP(CFP, AP);
1989 
1990   if (isa<ConstantPointerNull>(CV)) {
1991     AP.OutStreamer.EmitIntValue(0, Size);
1992     return;
1993   }
1994 
1995   if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(CV))
1996     return emitGlobalConstantDataSequential(CDS, AP);
1997 
1998   if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV))
1999     return emitGlobalConstantArray(CVA, AP);
2000 
2001   if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
2002     return emitGlobalConstantStruct(CVS, AP);
2003 
2004   if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
2005     // Look through bitcasts, which might not be able to be MCExpr'ized (e.g. of
2006     // vectors).
2007     if (CE->getOpcode() == Instruction::BitCast)
2008       return emitGlobalConstantImpl(CE->getOperand(0), AP);
2009 
2010     if (Size > 8) {
2011       // If the constant expression's size is greater than 64-bits, then we have
2012       // to emit the value in chunks. Try to constant fold the value and emit it
2013       // that way.
2014       Constant *New = ConstantFoldConstantExpression(CE, DL);
2015       if (New && New != CE)
2016         return emitGlobalConstantImpl(New, AP);
2017     }
2018   }
2019 
2020   if (const ConstantVector *V = dyn_cast<ConstantVector>(CV))
2021     return emitGlobalConstantVector(V, AP);
2022 
2023   // Otherwise, it must be a ConstantExpr.  Lower it to an MCExpr, then emit it
2024   // thread the streamer with EmitValue.
2025   AP.OutStreamer.EmitValue(lowerConstant(CV, AP), Size);
2026 }
2027 
2028 /// EmitGlobalConstant - Print a general LLVM constant to the .s file.
EmitGlobalConstant(const Constant * CV)2029 void AsmPrinter::EmitGlobalConstant(const Constant *CV) {
2030   uint64_t Size = TM.getDataLayout()->getTypeAllocSize(CV->getType());
2031   if (Size)
2032     emitGlobalConstantImpl(CV, *this);
2033   else if (MAI->hasSubsectionsViaSymbols()) {
2034     // If the global has zero size, emit a single byte so that two labels don't
2035     // look like they are at the same location.
2036     OutStreamer.EmitIntValue(0, 1);
2037   }
2038 }
2039 
EmitMachineConstantPoolValue(MachineConstantPoolValue * MCPV)2040 void AsmPrinter::EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) {
2041   // Target doesn't support this yet!
2042   llvm_unreachable("Target does not support EmitMachineConstantPoolValue");
2043 }
2044 
printOffset(int64_t Offset,raw_ostream & OS) const2045 void AsmPrinter::printOffset(int64_t Offset, raw_ostream &OS) const {
2046   if (Offset > 0)
2047     OS << '+' << Offset;
2048   else if (Offset < 0)
2049     OS << Offset;
2050 }
2051 
2052 //===----------------------------------------------------------------------===//
2053 // Symbol Lowering Routines.
2054 //===----------------------------------------------------------------------===//
2055 
2056 /// GetTempSymbol - Return the MCSymbol corresponding to the assembler
2057 /// temporary label with the specified stem and unique ID.
GetTempSymbol(Twine Name,unsigned ID) const2058 MCSymbol *AsmPrinter::GetTempSymbol(Twine Name, unsigned ID) const {
2059   const DataLayout *DL = TM.getDataLayout();
2060   return OutContext.GetOrCreateSymbol(Twine(DL->getPrivateGlobalPrefix()) +
2061                                       Name + Twine(ID));
2062 }
2063 
2064 /// GetTempSymbol - Return an assembler temporary label with the specified
2065 /// stem.
GetTempSymbol(Twine Name) const2066 MCSymbol *AsmPrinter::GetTempSymbol(Twine Name) const {
2067   const DataLayout *DL = TM.getDataLayout();
2068   return OutContext.GetOrCreateSymbol(Twine(DL->getPrivateGlobalPrefix())+
2069                                       Name);
2070 }
2071 
2072 
GetBlockAddressSymbol(const BlockAddress * BA) const2073 MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BlockAddress *BA) const {
2074   return MMI->getAddrLabelSymbol(BA->getBasicBlock());
2075 }
2076 
GetBlockAddressSymbol(const BasicBlock * BB) const2077 MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BasicBlock *BB) const {
2078   return MMI->getAddrLabelSymbol(BB);
2079 }
2080 
2081 /// GetCPISymbol - Return the symbol for the specified constant pool entry.
GetCPISymbol(unsigned CPID) const2082 MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
2083   const DataLayout *DL = TM.getDataLayout();
2084   return OutContext.GetOrCreateSymbol
2085     (Twine(DL->getPrivateGlobalPrefix()) + "CPI" + Twine(getFunctionNumber())
2086      + "_" + Twine(CPID));
2087 }
2088 
2089 /// GetJTISymbol - Return the symbol for the specified jump table entry.
GetJTISymbol(unsigned JTID,bool isLinkerPrivate) const2090 MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool isLinkerPrivate) const {
2091   return MF->getJTISymbol(JTID, OutContext, isLinkerPrivate);
2092 }
2093 
2094 /// GetJTSetSymbol - Return the symbol for the specified jump table .set
2095 /// FIXME: privatize to AsmPrinter.
GetJTSetSymbol(unsigned UID,unsigned MBBID) const2096 MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
2097   const DataLayout *DL = TM.getDataLayout();
2098   return OutContext.GetOrCreateSymbol
2099   (Twine(DL->getPrivateGlobalPrefix()) + Twine(getFunctionNumber()) + "_" +
2100    Twine(UID) + "_set_" + Twine(MBBID));
2101 }
2102 
getSymbolWithGlobalValueBase(const GlobalValue * GV,StringRef Suffix) const2103 MCSymbol *AsmPrinter::getSymbolWithGlobalValueBase(const GlobalValue *GV,
2104                                                    StringRef Suffix) const {
2105   return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, *Mang,
2106                                                            TM);
2107 }
2108 
2109 /// GetExternalSymbolSymbol - Return the MCSymbol for the specified
2110 /// ExternalSymbol.
GetExternalSymbolSymbol(StringRef Sym) const2111 MCSymbol *AsmPrinter::GetExternalSymbolSymbol(StringRef Sym) const {
2112   SmallString<60> NameStr;
2113   Mang->getNameWithPrefix(NameStr, Sym);
2114   return OutContext.GetOrCreateSymbol(NameStr.str());
2115 }
2116 
2117 
2118 
2119 /// PrintParentLoopComment - Print comments about parent loops of this one.
PrintParentLoopComment(raw_ostream & OS,const MachineLoop * Loop,unsigned FunctionNumber)2120 static void PrintParentLoopComment(raw_ostream &OS, const MachineLoop *Loop,
2121                                    unsigned FunctionNumber) {
2122   if (!Loop) return;
2123   PrintParentLoopComment(OS, Loop->getParentLoop(), FunctionNumber);
2124   OS.indent(Loop->getLoopDepth()*2)
2125     << "Parent Loop BB" << FunctionNumber << "_"
2126     << Loop->getHeader()->getNumber()
2127     << " Depth=" << Loop->getLoopDepth() << '\n';
2128 }
2129 
2130 
2131 /// PrintChildLoopComment - Print comments about child loops within
2132 /// the loop for this basic block, with nesting.
PrintChildLoopComment(raw_ostream & OS,const MachineLoop * Loop,unsigned FunctionNumber)2133 static void PrintChildLoopComment(raw_ostream &OS, const MachineLoop *Loop,
2134                                   unsigned FunctionNumber) {
2135   // Add child loop information
2136   for (const MachineLoop *CL : *Loop) {
2137     OS.indent(CL->getLoopDepth()*2)
2138       << "Child Loop BB" << FunctionNumber << "_"
2139       << CL->getHeader()->getNumber() << " Depth " << CL->getLoopDepth()
2140       << '\n';
2141     PrintChildLoopComment(OS, CL, FunctionNumber);
2142   }
2143 }
2144 
2145 /// emitBasicBlockLoopComments - Pretty-print comments for basic blocks.
emitBasicBlockLoopComments(const MachineBasicBlock & MBB,const MachineLoopInfo * LI,const AsmPrinter & AP)2146 static void emitBasicBlockLoopComments(const MachineBasicBlock &MBB,
2147                                        const MachineLoopInfo *LI,
2148                                        const AsmPrinter &AP) {
2149   // Add loop depth information
2150   const MachineLoop *Loop = LI->getLoopFor(&MBB);
2151   if (!Loop) return;
2152 
2153   MachineBasicBlock *Header = Loop->getHeader();
2154   assert(Header && "No header for loop");
2155 
2156   // If this block is not a loop header, just print out what is the loop header
2157   // and return.
2158   if (Header != &MBB) {
2159     AP.OutStreamer.AddComment("  in Loop: Header=BB" +
2160                               Twine(AP.getFunctionNumber())+"_" +
2161                               Twine(Loop->getHeader()->getNumber())+
2162                               " Depth="+Twine(Loop->getLoopDepth()));
2163     return;
2164   }
2165 
2166   // Otherwise, it is a loop header.  Print out information about child and
2167   // parent loops.
2168   raw_ostream &OS = AP.OutStreamer.GetCommentOS();
2169 
2170   PrintParentLoopComment(OS, Loop->getParentLoop(), AP.getFunctionNumber());
2171 
2172   OS << "=>";
2173   OS.indent(Loop->getLoopDepth()*2-2);
2174 
2175   OS << "This ";
2176   if (Loop->empty())
2177     OS << "Inner ";
2178   OS << "Loop Header: Depth=" + Twine(Loop->getLoopDepth()) << '\n';
2179 
2180   PrintChildLoopComment(OS, Loop, AP.getFunctionNumber());
2181 }
2182 
2183 
2184 /// EmitBasicBlockStart - This method prints the label for the specified
2185 /// MachineBasicBlock, an alignment (if present) and a comment describing
2186 /// it if appropriate.
EmitBasicBlockStart(const MachineBasicBlock & MBB) const2187 void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock &MBB) const {
2188   // Emit an alignment directive for this block, if needed.
2189   if (unsigned Align = MBB.getAlignment())
2190     EmitAlignment(Align);
2191 
2192   // If the block has its address taken, emit any labels that were used to
2193   // reference the block.  It is possible that there is more than one label
2194   // here, because multiple LLVM BB's may have been RAUW'd to this block after
2195   // the references were generated.
2196   if (MBB.hasAddressTaken()) {
2197     const BasicBlock *BB = MBB.getBasicBlock();
2198     if (isVerbose())
2199       OutStreamer.AddComment("Block address taken");
2200 
2201     std::vector<MCSymbol*> Symbols = MMI->getAddrLabelSymbolToEmit(BB);
2202     for (auto *Sym : Symbols)
2203       OutStreamer.EmitLabel(Sym);
2204   }
2205 
2206   // Print some verbose block comments.
2207   if (isVerbose()) {
2208     if (const BasicBlock *BB = MBB.getBasicBlock())
2209       if (BB->hasName())
2210         OutStreamer.AddComment("%" + BB->getName());
2211     emitBasicBlockLoopComments(MBB, LI, *this);
2212   }
2213 
2214   // Print the main label for the block.
2215   if (MBB.pred_empty() || isBlockOnlyReachableByFallthrough(&MBB)) {
2216     if (isVerbose()) {
2217       // NOTE: Want this comment at start of line, don't emit with AddComment.
2218       OutStreamer.emitRawComment(" BB#" + Twine(MBB.getNumber()) + ":", false);
2219     }
2220   } else {
2221     OutStreamer.EmitLabel(MBB.getSymbol());
2222   }
2223 }
2224 
EmitVisibility(MCSymbol * Sym,unsigned Visibility,bool IsDefinition) const2225 void AsmPrinter::EmitVisibility(MCSymbol *Sym, unsigned Visibility,
2226                                 bool IsDefinition) const {
2227   MCSymbolAttr Attr = MCSA_Invalid;
2228 
2229   switch (Visibility) {
2230   default: break;
2231   case GlobalValue::HiddenVisibility:
2232     if (IsDefinition)
2233       Attr = MAI->getHiddenVisibilityAttr();
2234     else
2235       Attr = MAI->getHiddenDeclarationVisibilityAttr();
2236     break;
2237   case GlobalValue::ProtectedVisibility:
2238     Attr = MAI->getProtectedVisibilityAttr();
2239     break;
2240   }
2241 
2242   if (Attr != MCSA_Invalid)
2243     OutStreamer.EmitSymbolAttribute(Sym, Attr);
2244 }
2245 
2246 /// isBlockOnlyReachableByFallthough - Return true if the basic block has
2247 /// exactly one predecessor and the control transfer mechanism between
2248 /// the predecessor and this block is a fall-through.
2249 bool AsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock * MBB) const2250 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
2251   // If this is a landing pad, it isn't a fall through.  If it has no preds,
2252   // then nothing falls through to it.
2253   if (MBB->isLandingPad() || MBB->pred_empty())
2254     return false;
2255 
2256   // If there isn't exactly one predecessor, it can't be a fall through.
2257   if (MBB->pred_size() > 1)
2258     return false;
2259 
2260   // The predecessor has to be immediately before this block.
2261   MachineBasicBlock *Pred = *MBB->pred_begin();
2262   if (!Pred->isLayoutSuccessor(MBB))
2263     return false;
2264 
2265   // If the block is completely empty, then it definitely does fall through.
2266   if (Pred->empty())
2267     return true;
2268 
2269   // Check the terminators in the previous blocks
2270   for (const auto &MI : Pred->terminators()) {
2271     // If it is not a simple branch, we are in a table somewhere.
2272     if (!MI.isBranch() || MI.isIndirectBranch())
2273       return false;
2274 
2275     // If we are the operands of one of the branches, this is not a fall
2276     // through. Note that targets with delay slots will usually bundle
2277     // terminators with the delay slot instruction.
2278     for (ConstMIBundleOperands OP(&MI); OP.isValid(); ++OP) {
2279       if (OP->isJTI())
2280         return false;
2281       if (OP->isMBB() && OP->getMBB() == MBB)
2282         return false;
2283     }
2284   }
2285 
2286   return true;
2287 }
2288 
2289 
2290 
GetOrCreateGCPrinter(GCStrategy & S)2291 GCMetadataPrinter *AsmPrinter::GetOrCreateGCPrinter(GCStrategy &S) {
2292   if (!S.usesMetadata())
2293     return nullptr;
2294 
2295   gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
2296   gcp_map_type::iterator GCPI = GCMap.find(&S);
2297   if (GCPI != GCMap.end())
2298     return GCPI->second.get();
2299 
2300   const char *Name = S.getName().c_str();
2301 
2302   for (GCMetadataPrinterRegistry::iterator
2303          I = GCMetadataPrinterRegistry::begin(),
2304          E = GCMetadataPrinterRegistry::end(); I != E; ++I)
2305     if (strcmp(Name, I->getName()) == 0) {
2306       std::unique_ptr<GCMetadataPrinter> GMP = I->instantiate();
2307       GMP->S = &S;
2308       auto IterBool = GCMap.insert(std::make_pair(&S, std::move(GMP)));
2309       return IterBool.first->second.get();
2310     }
2311 
2312   report_fatal_error("no GCMetadataPrinter registered for GC: " + Twine(Name));
2313 }
2314 
2315 /// Pin vtable to this file.
~AsmPrinterHandler()2316 AsmPrinterHandler::~AsmPrinterHandler() {}
2317