1 //===- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework ---------*- C++ -*-===//
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 contains a class to be used as the base class for target specific
11 // asm writers.  This class primarily handles common functionality used by
12 // all asm writers.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_CODEGEN_ASMPRINTER_H
17 #define LLVM_CODEGEN_ASMPRINTER_H
18 
19 #include "llvm/ADT/MapVector.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringRef.h"
22 #include "llvm/ADT/Twine.h"
23 #include "llvm/CodeGen/DwarfStringPoolEntry.h"
24 #include "llvm/CodeGen/MachineFunctionPass.h"
25 #include "llvm/IR/InlineAsm.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/SourceMgr.h"
29 #include <cstdint>
30 #include <memory>
31 #include <utility>
32 #include <vector>
33 
34 namespace llvm {
35 
36 class AsmPrinterHandler;
37 class BasicBlock;
38 class BlockAddress;
39 class Constant;
40 class ConstantArray;
41 class DataLayout;
42 class DIE;
43 class DIEAbbrev;
44 class DwarfDebug;
45 class GCMetadataPrinter;
46 class GCStrategy;
47 class GlobalIndirectSymbol;
48 class GlobalObject;
49 class GlobalValue;
50 class GlobalVariable;
51 class MachineBasicBlock;
52 class MachineConstantPoolValue;
53 class MachineDominatorTree;
54 class MachineFunction;
55 class MachineInstr;
56 class MachineJumpTableInfo;
57 class MachineLoopInfo;
58 class MachineModuleInfo;
59 class MachineOptimizationRemarkEmitter;
60 class MCAsmInfo;
61 class MCCFIInstruction;
62 struct MCCodePaddingContext;
63 class MCContext;
64 class MCExpr;
65 class MCInst;
66 class MCSection;
67 class MCStreamer;
68 class MCSubtargetInfo;
69 class MCSymbol;
70 class MCTargetOptions;
71 class MDNode;
72 class Module;
73 class raw_ostream;
74 class StackMaps;
75 class TargetLoweringObjectFile;
76 class TargetMachine;
77 
78 /// This class is intended to be used as a driving class for all asm writers.
79 class AsmPrinter : public MachineFunctionPass {
80 public:
81   /// Target machine description.
82   TargetMachine &TM;
83 
84   /// Target Asm Printer information.
85   const MCAsmInfo *MAI;
86 
87   /// This is the context for the output file that we are streaming. This owns
88   /// all of the global MC-related objects for the generated translation unit.
89   MCContext &OutContext;
90 
91   /// This is the MCStreamer object for the file we are generating. This
92   /// contains the transient state for the current translation unit that we are
93   /// generating (such as the current section etc).
94   std::unique_ptr<MCStreamer> OutStreamer;
95 
96   /// The current machine function.
97   MachineFunction *MF = nullptr;
98 
99   /// This is a pointer to the current MachineModuleInfo.
100   MachineModuleInfo *MMI = nullptr;
101 
102   /// This is a pointer to the current MachineLoopInfo.
103   MachineDominatorTree *MDT = nullptr;
104 
105   /// This is a pointer to the current MachineLoopInfo.
106   MachineLoopInfo *MLI = nullptr;
107 
108   /// Optimization remark emitter.
109   MachineOptimizationRemarkEmitter *ORE;
110 
111   /// The symbol for the current function. This is recalculated at the beginning
112   /// of each call to runOnMachineFunction().
113   MCSymbol *CurrentFnSym = nullptr;
114 
115   /// The symbol used to represent the start of the current function for the
116   /// purpose of calculating its size (e.g. using the .size directive). By
117   /// default, this is equal to CurrentFnSym.
118   MCSymbol *CurrentFnSymForSize = nullptr;
119 
120   /// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of
121   /// its number of uses by other globals.
122   using GOTEquivUsePair = std::pair<const GlobalVariable *, unsigned>;
123   MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs;
124 
125   /// Enable print [latency:throughput] in output.
126   bool EnablePrintSchedInfo = false;
127 
128 private:
129   MCSymbol *CurrentFnBegin = nullptr;
130   MCSymbol *CurrentFnEnd = nullptr;
131   MCSymbol *CurExceptionSym = nullptr;
132 
133   // The garbage collection metadata printer table.
134   void *GCMetadataPrinters = nullptr; // Really a DenseMap.
135 
136   /// Emit comments in assembly output if this is true.
137   bool VerboseAsm;
138 
139   static char ID;
140 
141 protected:
142   /// Protected struct HandlerInfo and Handlers permit target extended
143   /// AsmPrinter adds their own handlers.
144   struct HandlerInfo {
145     AsmPrinterHandler *Handler;
146     const char *TimerName;
147     const char *TimerDescription;
148     const char *TimerGroupName;
149     const char *TimerGroupDescription;
150 
HandlerInfoHandlerInfo151     HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName,
152                 const char *TimerDescription, const char *TimerGroupName,
153                 const char *TimerGroupDescription)
154         : Handler(Handler), TimerName(TimerName),
155           TimerDescription(TimerDescription), TimerGroupName(TimerGroupName),
156           TimerGroupDescription(TimerGroupDescription) {}
157   };
158 
159   /// A vector of all debug/EH info emitters we should use. This vector
160   /// maintains ownership of the emitters.
161   SmallVector<HandlerInfo, 1> Handlers;
162 
163 public:
164   struct SrcMgrDiagInfo {
165     SourceMgr SrcMgr;
166     std::vector<const MDNode *> LocInfos;
167     LLVMContext::InlineAsmDiagHandlerTy DiagHandler;
168     void *DiagContext;
169   };
170 
171 private:
172   /// If generated on the fly this own the instance.
173   std::unique_ptr<MachineDominatorTree> OwnedMDT;
174 
175   /// If generated on the fly this own the instance.
176   std::unique_ptr<MachineLoopInfo> OwnedMLI;
177 
178   /// Structure for generating diagnostics for inline assembly. Only initialised
179   /// when necessary.
180   mutable std::unique_ptr<SrcMgrDiagInfo> DiagInfo;
181 
182   /// If the target supports dwarf debug info, this pointer is non-null.
183   DwarfDebug *DD = nullptr;
184 
185   /// If the current module uses dwarf CFI annotations strictly for debugging.
186   bool isCFIMoveForDebugging = false;
187 
188 protected:
189   explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
190 
191 public:
192   ~AsmPrinter() override;
193 
getDwarfDebug()194   DwarfDebug *getDwarfDebug() { return DD; }
getDwarfDebug()195   DwarfDebug *getDwarfDebug() const { return DD; }
196 
197   uint16_t getDwarfVersion() const;
198   void setDwarfVersion(uint16_t Version);
199 
200   bool isPositionIndependent() const;
201 
202   /// Return true if assembly output should contain comments.
isVerbose()203   bool isVerbose() const { return VerboseAsm; }
204 
205   /// Return a unique ID for the current function.
206   unsigned getFunctionNumber() const;
207 
208   /// Return symbol for the function pseudo stack if the stack frame is not a
209   /// register based.
getFunctionFrameSymbol()210   virtual const MCSymbol *getFunctionFrameSymbol() const { return nullptr; }
211 
getFunctionBegin()212   MCSymbol *getFunctionBegin() const { return CurrentFnBegin; }
getFunctionEnd()213   MCSymbol *getFunctionEnd() const { return CurrentFnEnd; }
214   MCSymbol *getCurExceptionSym();
215 
216   /// Return information about object file lowering.
217   const TargetLoweringObjectFile &getObjFileLowering() const;
218 
219   /// Return information about data layout.
220   const DataLayout &getDataLayout() const;
221 
222   /// Return the pointer size from the TargetMachine
223   unsigned getPointerSize() const;
224 
225   /// Return information about subtarget.
226   const MCSubtargetInfo &getSubtargetInfo() const;
227 
228   void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
229 
230   /// Return the current section we are emitting to.
231   const MCSection *getCurrentSection() const;
232 
233   void getNameWithPrefix(SmallVectorImpl<char> &Name,
234                          const GlobalValue *GV) const;
235 
236   MCSymbol *getSymbol(const GlobalValue *GV) const;
237 
238   //===------------------------------------------------------------------===//
239   // XRay instrumentation implementation.
240   //===------------------------------------------------------------------===//
241 public:
242   // This describes the kind of sled we're storing in the XRay table.
243   enum class SledKind : uint8_t {
244     FUNCTION_ENTER = 0,
245     FUNCTION_EXIT = 1,
246     TAIL_CALL = 2,
247     LOG_ARGS_ENTER = 3,
248     CUSTOM_EVENT = 4,
249     TYPED_EVENT = 5,
250   };
251 
252   // The table will contain these structs that point to the sled, the function
253   // containing the sled, and what kind of sled (and whether they should always
254   // be instrumented). We also use a version identifier that the runtime can use
255   // to decide what to do with the sled, depending on the version of the sled.
256   struct XRayFunctionEntry {
257     const MCSymbol *Sled;
258     const MCSymbol *Function;
259     SledKind Kind;
260     bool AlwaysInstrument;
261     const class Function *Fn;
262     uint8_t Version;
263 
264     void emit(int, MCStreamer *, const MCSymbol *) const;
265   };
266 
267   // All the sleds to be emitted.
268   SmallVector<XRayFunctionEntry, 4> Sleds;
269 
270   // A unique ID used for ELF sections associated with a particular function.
271   unsigned XRayFnUniqueID = 0;
272 
273   // Helper function to record a given XRay sled.
274   void recordSled(MCSymbol *Sled, const MachineInstr &MI, SledKind Kind,
275                   uint8_t Version = 0);
276 
277   /// Emit a table with all XRay instrumentation points.
278   void emitXRayTable();
279 
280   //===------------------------------------------------------------------===//
281   // MachineFunctionPass Implementation.
282   //===------------------------------------------------------------------===//
283 
284   /// Record analysis usage.
285   void getAnalysisUsage(AnalysisUsage &AU) const override;
286 
287   /// Set up the AsmPrinter when we are working on a new module. If your pass
288   /// overrides this, it must make sure to explicitly call this implementation.
289   bool doInitialization(Module &M) override;
290 
291   /// Shut down the asmprinter. If you override this in your pass, you must make
292   /// sure to call it explicitly.
293   bool doFinalization(Module &M) override;
294 
295   /// Emit the specified function out to the OutStreamer.
runOnMachineFunction(MachineFunction & MF)296   bool runOnMachineFunction(MachineFunction &MF) override {
297     SetupMachineFunction(MF);
298     EmitFunctionBody();
299     return false;
300   }
301 
302   //===------------------------------------------------------------------===//
303   // Coarse grained IR lowering routines.
304   //===------------------------------------------------------------------===//
305 
306   /// This should be called when a new MachineFunction is being processed from
307   /// runOnMachineFunction.
308   void SetupMachineFunction(MachineFunction &MF);
309 
310   /// This method emits the body and trailer for a function.
311   void EmitFunctionBody();
312 
313   void emitCFIInstruction(const MachineInstr &MI);
314 
315   void emitFrameAlloc(const MachineInstr &MI);
316 
317   void emitStackSizeSection(const MachineFunction &MF);
318 
319   enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
320   CFIMoveType needsCFIMoves() const;
321 
322   /// Returns false if needsCFIMoves() == CFI_M_EH for any function
323   /// in the module.
needsOnlyDebugCFIMoves()324   bool needsOnlyDebugCFIMoves() const { return isCFIMoveForDebugging; }
325 
326   bool needsSEHMoves();
327 
328   /// Print to the current output stream assembly representations of the
329   /// constants in the constant pool MCP. This is used to print out constants
330   /// which have been "spilled to memory" by the code generator.
331   virtual void EmitConstantPool();
332 
333   /// Print assembly representations of the jump tables used by the current
334   /// function to the current output stream.
335   virtual void EmitJumpTableInfo();
336 
337   /// Emit the specified global variable to the .s file.
338   virtual void EmitGlobalVariable(const GlobalVariable *GV);
339 
340   /// Check to see if the specified global is a special global used by LLVM. If
341   /// so, emit it and return true, otherwise do nothing and return false.
342   bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
343 
344   /// Emit an alignment directive to the specified power of two boundary. For
345   /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
346   /// global value is specified, and if that global has an explicit alignment
347   /// requested, it will override the alignment request if required for
348   /// correctness.
349   void EmitAlignment(unsigned NumBits, const GlobalObject *GV = nullptr) const;
350 
351   /// Lower the specified LLVM Constant to an MCExpr.
352   virtual const MCExpr *lowerConstant(const Constant *CV);
353 
354   /// Print a general LLVM constant to the .s file.
355   void EmitGlobalConstant(const DataLayout &DL, const Constant *CV);
356 
357   /// Unnamed constant global variables solely contaning a pointer to
358   /// another globals variable act like a global variable "proxy", or GOT
359   /// equivalents, i.e., it's only used to hold the address of the latter. One
360   /// optimization is to replace accesses to these proxies by using the GOT
361   /// entry for the final global instead. Hence, we select GOT equivalent
362   /// candidates among all the module global variables, avoid emitting them
363   /// unnecessarily and finally replace references to them by pc relative
364   /// accesses to GOT entries.
365   void computeGlobalGOTEquivs(Module &M);
366 
367   /// Constant expressions using GOT equivalent globals may not be
368   /// eligible for PC relative GOT entry conversion, in such cases we need to
369   /// emit the proxies we previously omitted in EmitGlobalVariable.
370   void emitGlobalGOTEquivs();
371 
372   /// Emit the stack maps.
373   void emitStackMaps(StackMaps &SM);
374 
375   //===------------------------------------------------------------------===//
376   // Overridable Hooks
377   //===------------------------------------------------------------------===//
378 
379   // Targets can, or in the case of EmitInstruction, must implement these to
380   // customize output.
381 
382   /// This virtual method can be overridden by targets that want to emit
383   /// something at the start of their file.
EmitStartOfAsmFile(Module &)384   virtual void EmitStartOfAsmFile(Module &) {}
385 
386   /// This virtual method can be overridden by targets that want to emit
387   /// something at the end of their file.
EmitEndOfAsmFile(Module &)388   virtual void EmitEndOfAsmFile(Module &) {}
389 
390   /// Targets can override this to emit stuff before the first basic block in
391   /// the function.
EmitFunctionBodyStart()392   virtual void EmitFunctionBodyStart() {}
393 
394   /// Targets can override this to emit stuff after the last basic block in the
395   /// function.
EmitFunctionBodyEnd()396   virtual void EmitFunctionBodyEnd() {}
397 
398   /// Targets can override this to emit stuff at the start of a basic block.
399   /// By default, this method prints the label for the specified
400   /// MachineBasicBlock, an alignment (if present) and a comment describing it
401   /// if appropriate.
402   virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;
403 
404   /// Targets can override this to emit stuff at the end of a basic block.
405   virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB);
406 
407   /// Targets should implement this to emit instructions.
EmitInstruction(const MachineInstr *)408   virtual void EmitInstruction(const MachineInstr *) {
409     llvm_unreachable("EmitInstruction not implemented");
410   }
411 
412   /// Return the symbol for the specified constant pool entry.
413   virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
414 
415   virtual void EmitFunctionEntryLabel();
416 
417   virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
418 
419   /// Targets can override this to change how global constants that are part of
420   /// a C++ static/global constructor list are emitted.
EmitXXStructor(const DataLayout & DL,const Constant * CV)421   virtual void EmitXXStructor(const DataLayout &DL, const Constant *CV) {
422     EmitGlobalConstant(DL, CV);
423   }
424 
425   /// Return true if the basic block has exactly one predecessor and the control
426   /// transfer mechanism between the predecessor and this block is a
427   /// fall-through.
428   virtual bool
429   isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
430 
431   /// Targets can override this to customize the output of IMPLICIT_DEF
432   /// instructions in verbose mode.
433   virtual void emitImplicitDef(const MachineInstr *MI) const;
434 
435   //===------------------------------------------------------------------===//
436   // Symbol Lowering Routines.
437   //===------------------------------------------------------------------===//
438 
439   MCSymbol *createTempSymbol(const Twine &Name) const;
440 
441   /// Return the MCSymbol for a private symbol with global value name as its
442   /// base, with the specified suffix.
443   MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
444                                          StringRef Suffix) const;
445 
446   /// Return the MCSymbol for the specified ExternalSymbol.
447   MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
448 
449   /// Return the symbol for the specified jump table entry.
450   MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
451 
452   /// Return the symbol for the specified jump table .set
453   /// FIXME: privatize to AsmPrinter.
454   MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
455 
456   /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
457   /// basic block.
458   MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
459   MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
460 
461   //===------------------------------------------------------------------===//
462   // Emission Helper Routines.
463   //===------------------------------------------------------------------===//
464 
465   /// This is just convenient handler for printing offsets.
466   void printOffset(int64_t Offset, raw_ostream &OS) const;
467 
468   /// Emit a byte directive and value.
469   void emitInt8(int Value) const;
470 
471   /// Emit a short directive and value.
472   void emitInt16(int Value) const;
473 
474   /// Emit a long directive and value.
475   void emitInt32(int Value) const;
476 
477   /// Emit a long long directive and value.
478   void emitInt64(uint64_t Value) const;
479 
480   /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
481   /// is specified by Size and Hi/Lo specify the labels.  This implicitly uses
482   /// .set if it is available.
483   void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
484                            unsigned Size) const;
485 
486   /// Emit something like ".uleb128 Hi-Lo".
487   void EmitLabelDifferenceAsULEB128(const MCSymbol *Hi,
488                                     const MCSymbol *Lo) const;
489 
490   /// Emit something like ".long Label+Offset" where the size in bytes of the
491   /// directive is specified by Size and Label specifies the label.  This
492   /// implicitly uses .set if it is available.
493   void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
494                            unsigned Size, bool IsSectionRelative = false) const;
495 
496   /// Emit something like ".long Label" where the size in bytes of the directive
497   /// is specified by Size and Label specifies the label.
498   void EmitLabelReference(const MCSymbol *Label, unsigned Size,
499                           bool IsSectionRelative = false) const {
500     EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
501   }
502 
503   /// Emit something like ".long Label + Offset".
504   void EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const;
505 
506   //===------------------------------------------------------------------===//
507   // Dwarf Emission Helper Routines
508   //===------------------------------------------------------------------===//
509 
510   /// Emit the specified signed leb128 value.
511   void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
512 
513   /// Emit the specified unsigned leb128 value.
514   void EmitULEB128(uint64_t Value, const char *Desc = nullptr) const;
515 
516   /// Emit a .byte 42 directive that corresponds to an encoding.  If verbose
517   /// assembly output is enabled, we output comments describing the encoding.
518   /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
519   void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
520 
521   /// Return the size of the encoding in bytes.
522   unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
523 
524   /// Emit reference to a ttype global with a specified encoding.
525   void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
526 
527   /// Emit a reference to a symbol for use in dwarf. Different object formats
528   /// represent this in different ways. Some use a relocation others encode
529   /// the label offset in its section.
530   void emitDwarfSymbolReference(const MCSymbol *Label,
531                                 bool ForceOffset = false) const;
532 
533   /// Emit the 4-byte offset of a string from the start of its section.
534   ///
535   /// When possible, emit a DwarfStringPool section offset without any
536   /// relocations, and without using the symbol.  Otherwise, defers to \a
537   /// emitDwarfSymbolReference().
538   void emitDwarfStringOffset(DwarfStringPoolEntry S) const;
539 
540   /// Emit the 4-byte offset of a string from the start of its section.
emitDwarfStringOffset(DwarfStringPoolEntryRef S)541   void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
542     emitDwarfStringOffset(S.getEntry());
543   }
544 
545   /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
getISAEncoding()546   virtual unsigned getISAEncoding() { return 0; }
547 
548   /// Emit the directive and value for debug thread local expression
549   ///
550   /// \p Value - The value to emit.
551   /// \p Size - The size of the integer (in bytes) to emit.
552   virtual void EmitDebugValue(const MCExpr *Value, unsigned Size) const;
553 
554   //===------------------------------------------------------------------===//
555   // Dwarf Lowering Routines
556   //===------------------------------------------------------------------===//
557 
558   /// Emit frame instruction to describe the layout of the frame.
559   void emitCFIInstruction(const MCCFIInstruction &Inst) const;
560 
561   /// Emit Dwarf abbreviation table.
emitDwarfAbbrevs(const T & Abbrevs)562   template <typename T> void emitDwarfAbbrevs(const T &Abbrevs) const {
563     // For each abbreviation.
564     for (const auto &Abbrev : Abbrevs)
565       emitDwarfAbbrev(*Abbrev);
566 
567     // Mark end of abbreviations.
568     EmitULEB128(0, "EOM(3)");
569   }
570 
571   void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const;
572 
573   /// Recursively emit Dwarf DIE tree.
574   void emitDwarfDIE(const DIE &Die) const;
575 
576   //===------------------------------------------------------------------===//
577   // Inline Asm Support
578   //===------------------------------------------------------------------===//
579 
580   // These are hooks that targets can override to implement inline asm
581   // support.  These should probably be moved out of AsmPrinter someday.
582 
583   /// Print information related to the specified machine instr that is
584   /// independent of the operand, and may be independent of the instr itself.
585   /// This can be useful for portably encoding the comment character or other
586   /// bits of target-specific knowledge into the asmstrings.  The syntax used is
587   /// ${:comment}.  Targets can override this to add support for their own
588   /// strange codes.
589   virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
590                             const char *Code) const;
591 
592   /// Print the specified operand of MI, an INLINEASM instruction, using the
593   /// specified assembler variant.  Targets should override this to format as
594   /// appropriate.  This method can return true if the operand is erroneous.
595   virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
596                                unsigned AsmVariant, const char *ExtraCode,
597                                raw_ostream &OS);
598 
599   /// Print the specified operand of MI, an INLINEASM instruction, using the
600   /// specified assembler variant as an address. Targets should override this to
601   /// format as appropriate.  This method can return true if the operand is
602   /// erroneous.
603   virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
604                                      unsigned AsmVariant, const char *ExtraCode,
605                                      raw_ostream &OS);
606 
607   /// Let the target do anything it needs to do before emitting inlineasm.
608   /// \p StartInfo - the subtarget info before parsing inline asm
609   virtual void emitInlineAsmStart() const;
610 
611   /// Let the target do anything it needs to do after emitting inlineasm.
612   /// This callback can be used restore the original mode in case the
613   /// inlineasm contains directives to switch modes.
614   /// \p StartInfo - the original subtarget info before inline asm
615   /// \p EndInfo   - the final subtarget info after parsing the inline asm,
616   ///                or NULL if the value is unknown.
617   virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
618                                 const MCSubtargetInfo *EndInfo) const;
619 
620 private:
621   /// Private state for PrintSpecial()
622   // Assign a unique ID to this machine instruction.
623   mutable const MachineInstr *LastMI = nullptr;
624   mutable unsigned LastFn = 0;
625   mutable unsigned Counter = ~0U;
626 
627   /// This method emits the header for the current function.
628   virtual void EmitFunctionHeader();
629 
630   /// Emit a blob of inline asm to the output streamer.
631   void
632   EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
633                 const MCTargetOptions &MCOptions,
634                 const MDNode *LocMDNode = nullptr,
635                 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
636 
637   /// This method formats and emits the specified machine instruction that is an
638   /// inline asm.
639   void EmitInlineAsm(const MachineInstr *MI) const;
640 
641   /// Add inline assembly info to the diagnostics machinery, so we can
642   /// emit file and position info. Returns SrcMgr memory buffer position.
643   unsigned addInlineAsmDiagBuffer(StringRef AsmStr,
644                                   const MDNode *LocMDNode) const;
645 
646   //===------------------------------------------------------------------===//
647   // Internal Implementation Details
648   //===------------------------------------------------------------------===//
649 
650   /// This emits visibility information about symbol, if this is supported by
651   /// the target.
652   void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
653                       bool IsDefinition = true) const;
654 
655   void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
656 
657   void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
658                           const MachineBasicBlock *MBB, unsigned uid) const;
659   void EmitLLVMUsedList(const ConstantArray *InitList);
660   /// Emit llvm.ident metadata in an '.ident' directive.
661   void EmitModuleIdents(Module &M);
662   /// Emit bytes for llvm.commandline metadata.
663   void EmitModuleCommandLines(Module &M);
664   void EmitXXStructorList(const DataLayout &DL, const Constant *List,
665                           bool isCtor);
666 
667   GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &S);
668   /// Emit GlobalAlias or GlobalIFunc.
669   void emitGlobalIndirectSymbol(Module &M, const GlobalIndirectSymbol &GIS);
670   void setupCodePaddingContext(const MachineBasicBlock &MBB,
671                                MCCodePaddingContext &Context) const;
672 };
673 
674 } // end namespace llvm
675 
676 #endif // LLVM_CODEGEN_ASMPRINTER_H
677