include/llvm/CodeGen/AsmPrinter.h

   1 //===- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework ---------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains a class to be used as the base class for target specific
  10 // asm writers.  This class primarily handles common functionality used by
  11 // all asm writers.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_CODEGEN_ASMPRINTER_H
  16 #define LLVM_CODEGEN_ASMPRINTER_H
  17
  18 #include "llvm/ADT/MapVector.h"
  19 #include "llvm/ADT/SmallVector.h"
  20 #include "llvm/ADT/StringRef.h"
  21 #include "llvm/ADT/Twine.h"
  22 #include "llvm/CodeGen/AsmPrinterHandler.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 BasicBlock;
  37 class BlockAddress;
  38 class Constant;
  39 class ConstantArray;
  40 class DataLayout;
  41 class DIE;
  42 class DIEAbbrev;
  43 class DwarfDebug;
  44 class GCMetadataPrinter;
  45 class GCStrategy;
  46 class GlobalIndirectSymbol;
  47 class GlobalObject;
  48 class GlobalValue;
  49 class GlobalVariable;
  50 class MachineBasicBlock;
  51 class MachineConstantPoolValue;
  52 class MachineDominatorTree;
  53 class MachineFunction;
  54 class MachineInstr;
  55 class MachineJumpTableInfo;
  56 class MachineLoopInfo;
  57 class MachineModuleInfo;
  58 class MachineOptimizationRemarkEmitter;
  59 class MCAsmInfo;
  60 class MCCFIInstruction;
  61 struct MCCodePaddingContext;
  62 class MCContext;
  63 class MCExpr;
  64 class MCInst;
  65 class MCSection;
  66 class MCStreamer;
  67 class MCSubtargetInfo;
  68 class MCSymbol;
  69 class MCTargetOptions;
  70 class MDNode;
  71 class Module;
  72 class raw_ostream;
  73 class StackMaps;
  74 class TargetLoweringObjectFile;
  75 class TargetMachine;
  76
  77 /// This class is intended to be used as a driving class for all asm writers.
  78 class AsmPrinter : public MachineFunctionPass {
  79 public:
  80   /// Target machine description.
  81   TargetMachine &TM;
  82
  83   /// Target Asm Printer information.
  84   const MCAsmInfo *MAI;
  85
  86   /// This is the context for the output file that we are streaming. This owns
  87   /// all of the global MC-related objects for the generated translation unit.
  88   MCContext &OutContext;
  89
  90   /// This is the MCStreamer object for the file we are generating. This
  91   /// contains the transient state for the current translation unit that we are
  92   /// generating (such as the current section etc).
  93   std::unique_ptr<MCStreamer> OutStreamer;
  94
  95   /// The current machine function.
  96   MachineFunction *MF = nullptr;
  97
  98   /// This is a pointer to the current MachineModuleInfo.
  99   MachineModuleInfo *MMI = nullptr;
 100
 101   /// This is a pointer to the current MachineLoopInfo.
 102   MachineDominatorTree *MDT = nullptr;
 103
 104   /// This is a pointer to the current MachineLoopInfo.
 105   MachineLoopInfo *MLI = nullptr;
 106
 107   /// Optimization remark emitter.
 108   MachineOptimizationRemarkEmitter *ORE;
 109
 110   /// The symbol for the current function. This is recalculated at the beginning
 111   /// of each call to runOnMachineFunction().
 112   MCSymbol *CurrentFnSym = nullptr;
 113
 114   /// The symbol for the current function descriptor on AIX. This is created
 115   /// at the beginning of each call to SetupMachineFunction().
 116   MCSymbol *CurrentFnDescSym = nullptr;
 117
 118   /// The symbol used to represent the start of the current function for the
 119   /// purpose of calculating its size (e.g. using the .size directive). By
 120   /// default, this is equal to CurrentFnSym.
 121   MCSymbol *CurrentFnSymForSize = nullptr;
 122
 123   /// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of
 124   /// its number of uses by other globals.
 125   using GOTEquivUsePair = std::pair<const GlobalVariable *, unsigned>;
 126   MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs;
 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     std::unique_ptr<AsmPrinterHandler> Handler;
 146     const char *TimerName;
 147     const char *TimerDescription;
 148     const char *TimerGroupName;
 149     const char *TimerGroupDescription;
 150
 151     HandlerInfo(std::unique_ptr<AsmPrinterHandler> Handler,
 152                 const char *TimerName, const char *TimerDescription,
 153                 const char *TimerGroupName, const char *TimerGroupDescription)
 154         : Handler(std::move(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
 194   DwarfDebug *getDwarfDebug() { return DD; }
 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.
 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.
 210   virtual const MCSymbol *getFunctionFrameSymbol() const { return nullptr; }
 211
 212   MCSymbol *getFunctionBegin() const { return CurrentFnBegin; }
 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   /// Emits inital debug location directive.
 231   void emitInitialRawDwarfLocDirective(const MachineFunction &MF);
 232
 233   /// Return the current section we are emitting to.
 234   const MCSection *getCurrentSection() const;
 235
 236   void getNameWithPrefix(SmallVectorImpl<char> &Name,
 237                          const GlobalValue *GV) const;
 238
 239   MCSymbol *getSymbol(const GlobalValue *GV) const;
 240
 241   //===------------------------------------------------------------------===//
 242   // XRay instrumentation implementation.
 243   //===------------------------------------------------------------------===//
 244 public:
 245   // This describes the kind of sled we're storing in the XRay table.
 246   enum class SledKind : uint8_t {
 247     FUNCTION_ENTER = 0,
 248     FUNCTION_EXIT = 1,
 249     TAIL_CALL = 2,
 250     LOG_ARGS_ENTER = 3,
 251     CUSTOM_EVENT = 4,
 252     TYPED_EVENT = 5,
 253   };
 254
 255   // The table will contain these structs that point to the sled, the function
 256   // containing the sled, and what kind of sled (and whether they should always
 257   // be instrumented). We also use a version identifier that the runtime can use
 258   // to decide what to do with the sled, depending on the version of the sled.
 259   struct XRayFunctionEntry {
 260     const MCSymbol *Sled;
 261     const MCSymbol *Function;
 262     SledKind Kind;
 263     bool AlwaysInstrument;
 264     const class Function *Fn;
 265     uint8_t Version;
 266
 267     void emit(int, MCStreamer *, const MCSymbol *) const;
 268   };
 269
 270   // All the sleds to be emitted.
 271   SmallVector<XRayFunctionEntry, 4> Sleds;
 272
 273   // A unique ID used for ELF sections associated with a particular function.
 274   unsigned XRayFnUniqueID = 0;
 275
 276   // Helper function to record a given XRay sled.
 277   void recordSled(MCSymbol *Sled, const MachineInstr &MI, SledKind Kind,
 278                   uint8_t Version = 0);
 279
 280   /// Emit a table with all XRay instrumentation points.
 281   void emitXRayTable();
 282
 283   //===------------------------------------------------------------------===//
 284   // MachineFunctionPass Implementation.
 285   //===------------------------------------------------------------------===//
 286
 287   /// Record analysis usage.
 288   void getAnalysisUsage(AnalysisUsage &AU) const override;
 289
 290   /// Set up the AsmPrinter when we are working on a new module. If your pass
 291   /// overrides this, it must make sure to explicitly call this implementation.
 292   bool doInitialization(Module &M) override;
 293
 294   /// Shut down the asmprinter. If you override this in your pass, you must make
 295   /// sure to call it explicitly.
 296   bool doFinalization(Module &M) override;
 297
 298   /// Emit the specified function out to the OutStreamer.
 299   bool runOnMachineFunction(MachineFunction &MF) override {
 300     SetupMachineFunction(MF);
 301     EmitFunctionBody();
 302     return false;
 303   }
 304
 305   //===------------------------------------------------------------------===//
 306   // Coarse grained IR lowering routines.
 307   //===------------------------------------------------------------------===//
 308
 309   /// This should be called when a new MachineFunction is being processed from
 310   /// runOnMachineFunction.
 311   virtual void SetupMachineFunction(MachineFunction &MF);
 312
 313   /// This method emits the body and trailer for a function.
 314   void EmitFunctionBody();
 315
 316   void emitCFIInstruction(const MachineInstr &MI);
 317
 318   void emitFrameAlloc(const MachineInstr &MI);
 319
 320   void emitStackSizeSection(const MachineFunction &MF);
 321
 322   void emitRemarksSection(Module &M);
 323
 324   enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
 325   CFIMoveType needsCFIMoves() const;
 326
 327   /// Returns false if needsCFIMoves() == CFI_M_EH for any function
 328   /// in the module.
 329   bool needsOnlyDebugCFIMoves() const { return isCFIMoveForDebugging; }
 330
 331   bool needsSEHMoves();
 332
 333   /// Print to the current output stream assembly representations of the
 334   /// constants in the constant pool MCP. This is used to print out constants
 335   /// which have been "spilled to memory" by the code generator.
 336   virtual void EmitConstantPool();
 337
 338   /// Print assembly representations of the jump tables used by the current
 339   /// function to the current output stream.
 340   virtual void EmitJumpTableInfo();
 341
 342   /// Emit the specified global variable to the .s file.
 343   virtual void EmitGlobalVariable(const GlobalVariable *GV);
 344
 345   /// Check to see if the specified global is a special global used by LLVM. If
 346   /// so, emit it and return true, otherwise do nothing and return false.
 347   bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
 348
 349   /// Emit an alignment directive to the specified power of two boundary. If a
 350   /// global value is specified, and if that global has an explicit alignment
 351   /// requested, it will override the alignment request if required for
 352   /// correctness.
 353   void EmitAlignment(Align Alignment, const GlobalObject *GV = nullptr) const;
 354
 355   /// Lower the specified LLVM Constant to an MCExpr.
 356   virtual const MCExpr *lowerConstant(const Constant *CV);
 357
 358   /// Print a general LLVM constant to the .s file.
 359   void EmitGlobalConstant(const DataLayout &DL, const Constant *CV);
 360
 361   /// Unnamed constant global variables solely contaning a pointer to
 362   /// another globals variable act like a global variable "proxy", or GOT
 363   /// equivalents, i.e., it's only used to hold the address of the latter. One
 364   /// optimization is to replace accesses to these proxies by using the GOT
 365   /// entry for the final global instead. Hence, we select GOT equivalent
 366   /// candidates among all the module global variables, avoid emitting them
 367   /// unnecessarily and finally replace references to them by pc relative
 368   /// accesses to GOT entries.
 369   void computeGlobalGOTEquivs(Module &M);
 370
 371   /// Constant expressions using GOT equivalent globals may not be
 372   /// eligible for PC relative GOT entry conversion, in such cases we need to
 373   /// emit the proxies we previously omitted in EmitGlobalVariable.
 374   void emitGlobalGOTEquivs();
 375
 376   /// Emit the stack maps.
 377   void emitStackMaps(StackMaps &SM);
 378
 379   //===------------------------------------------------------------------===//
 380   // Overridable Hooks
 381   //===------------------------------------------------------------------===//
 382
 383   // Targets can, or in the case of EmitInstruction, must implement these to
 384   // customize output.
 385
 386   /// This virtual method can be overridden by targets that want to emit
 387   /// something at the start of their file.
 388   virtual void EmitStartOfAsmFile(Module &) {}
 389
 390   /// This virtual method can be overridden by targets that want to emit
 391   /// something at the end of their file.
 392   virtual void EmitEndOfAsmFile(Module &) {}
 393
 394   /// Targets can override this to emit stuff before the first basic block in
 395   /// the function.
 396   virtual void EmitFunctionBodyStart() {}
 397
 398   /// Targets can override this to emit stuff after the last basic block in the
 399   /// function.
 400   virtual void EmitFunctionBodyEnd() {}
 401
 402   /// Targets can override this to emit stuff at the start of a basic block.
 403   /// By default, this method prints the label for the specified
 404   /// MachineBasicBlock, an alignment (if present) and a comment describing it
 405   /// if appropriate.
 406   virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB);
 407
 408   /// Targets can override this to emit stuff at the end of a basic block.
 409   virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB);
 410
 411   /// Targets should implement this to emit instructions.
 412   virtual void EmitInstruction(const MachineInstr *) {
 413     llvm_unreachable("EmitInstruction not implemented");
 414   }
 415
 416   /// Return the symbol for the specified constant pool entry.
 417   virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
 418
 419   virtual void EmitFunctionEntryLabel();
 420
 421   virtual void EmitFunctionDescriptor() {
 422     llvm_unreachable("Function descriptor is target-specific.");
 423   }
 424
 425   virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
 426
 427   /// Targets can override this to change how global constants that are part of
 428   /// a C++ static/global constructor list are emitted.
 429   virtual void EmitXXStructor(const DataLayout &DL, const Constant *CV) {
 430     EmitGlobalConstant(DL, CV);
 431   }
 432
 433   /// Return true if the basic block has exactly one predecessor and the control
 434   /// transfer mechanism between the predecessor and this block is a
 435   /// fall-through.
 436   virtual bool
 437   isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
 438
 439   /// Targets can override this to customize the output of IMPLICIT_DEF
 440   /// instructions in verbose mode.
 441   virtual void emitImplicitDef(const MachineInstr *MI) const;
 442
 443   //===------------------------------------------------------------------===//
 444   // Symbol Lowering Routines.
 445   //===------------------------------------------------------------------===//
 446
 447   MCSymbol *createTempSymbol(const Twine &Name) const;
 448
 449   /// Return the MCSymbol for a private symbol with global value name as its
 450   /// base, with the specified suffix.
 451   MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
 452                                          StringRef Suffix) const;
 453
 454   /// Return the MCSymbol for the specified ExternalSymbol.
 455   MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
 456
 457   /// Return the symbol for the specified jump table entry.
 458   MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
 459
 460   /// Return the symbol for the specified jump table .set
 461   /// FIXME: privatize to AsmPrinter.
 462   MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
 463
 464   /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
 465   /// basic block.
 466   MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
 467   MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
 468
 469   //===------------------------------------------------------------------===//
 470   // Emission Helper Routines.
 471   //===------------------------------------------------------------------===//
 472
 473   /// This is just convenient handler for printing offsets.
 474   void printOffset(int64_t Offset, raw_ostream &OS) const;
 475
 476   /// Emit a byte directive and value.
 477   void emitInt8(int Value) const;
 478
 479   /// Emit a short directive and value.
 480   void emitInt16(int Value) const;
 481
 482   /// Emit a long directive and value.
 483   void emitInt32(int Value) const;
 484
 485   /// Emit a long long directive and value.
 486   void emitInt64(uint64_t Value) const;
 487
 488   /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
 489   /// is specified by Size and Hi/Lo specify the labels.  This implicitly uses
 490   /// .set if it is available.
 491   void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
 492                            unsigned Size) const;
 493
 494   /// Emit something like ".uleb128 Hi-Lo".
 495   void EmitLabelDifferenceAsULEB128(const MCSymbol *Hi,
 496                                     const MCSymbol *Lo) const;
 497
 498   /// Emit something like ".long Label+Offset" where the size in bytes of the
 499   /// directive is specified by Size and Label specifies the label.  This
 500   /// implicitly uses .set if it is available.
 501   void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
 502                            unsigned Size, bool IsSectionRelative = false) const;
 503
 504   /// Emit something like ".long Label" where the size in bytes of the directive
 505   /// is specified by Size and Label specifies the label.
 506   void EmitLabelReference(const MCSymbol *Label, unsigned Size,
 507                           bool IsSectionRelative = false) const {
 508     EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
 509   }
 510
 511   /// Emit something like ".long Label + Offset".
 512   void EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const;
 513
 514   //===------------------------------------------------------------------===//
 515   // Dwarf Emission Helper Routines
 516   //===------------------------------------------------------------------===//
 517
 518   /// Emit the specified signed leb128 value.
 519   void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
 520
 521   /// Emit the specified unsigned leb128 value.
 522   void EmitULEB128(uint64_t Value, const char *Desc = nullptr, unsigned PadTo = 0) const;
 523
 524   /// Emit a .byte 42 directive that corresponds to an encoding.  If verbose
 525   /// assembly output is enabled, we output comments describing the encoding.
 526   /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
 527   void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
 528
 529   /// Return the size of the encoding in bytes.
 530   unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
 531
 532   /// Emit reference to a ttype global with a specified encoding.
 533   void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
 534
 535   /// Emit a reference to a symbol for use in dwarf. Different object formats
 536   /// represent this in different ways. Some use a relocation others encode
 537   /// the label offset in its section.
 538   void emitDwarfSymbolReference(const MCSymbol *Label,
 539                                 bool ForceOffset = false) const;
 540
 541   /// Emit the 4-byte offset of a string from the start of its section.
 542   ///
 543   /// When possible, emit a DwarfStringPool section offset without any
 544   /// relocations, and without using the symbol.  Otherwise, defers to \a
 545   /// emitDwarfSymbolReference().
 546   void emitDwarfStringOffset(DwarfStringPoolEntry S) const;
 547
 548   /// Emit the 4-byte offset of a string from the start of its section.
 549   void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
 550     emitDwarfStringOffset(S.getEntry());
 551   }
 552
 553   /// Emit reference to a call site with a specified encoding
 554   void EmitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo,
 555                           unsigned Encoding) const;
 556   /// Emit an integer value corresponding to the call site encoding
 557   void EmitCallSiteValue(uint64_t Value, unsigned Encoding) const;
 558
 559   /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
 560   virtual unsigned getISAEncoding() { return 0; }
 561
 562   /// Emit the directive and value for debug thread local expression
 563   ///
 564   /// \p Value - The value to emit.
 565   /// \p Size - The size of the integer (in bytes) to emit.
 566   virtual void EmitDebugValue(const MCExpr *Value, unsigned Size) const;
 567
 568   //===------------------------------------------------------------------===//
 569   // Dwarf Lowering Routines
 570   //===------------------------------------------------------------------===//
 571
 572   /// Emit frame instruction to describe the layout of the frame.
 573   void emitCFIInstruction(const MCCFIInstruction &Inst) const;
 574
 575   /// Emit Dwarf abbreviation table.
 576   template <typename T> void emitDwarfAbbrevs(const T &Abbrevs) const {
 577     // For each abbreviation.
 578     for (const auto &Abbrev : Abbrevs)
 579       emitDwarfAbbrev(*Abbrev);
 580
 581     // Mark end of abbreviations.
 582     EmitULEB128(0, "EOM(3)");
 583   }
 584
 585   void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const;
 586
 587   /// Recursively emit Dwarf DIE tree.
 588   void emitDwarfDIE(const DIE &Die) const;
 589
 590   //===------------------------------------------------------------------===//
 591   // Inline Asm Support
 592   //===------------------------------------------------------------------===//
 593
 594   // These are hooks that targets can override to implement inline asm
 595   // support.  These should probably be moved out of AsmPrinter someday.
 596
 597   /// Print information related to the specified machine instr that is
 598   /// independent of the operand, and may be independent of the instr itself.
 599   /// This can be useful for portably encoding the comment character or other
 600   /// bits of target-specific knowledge into the asmstrings.  The syntax used is
 601   /// ${:comment}.  Targets can override this to add support for their own
 602   /// strange codes.
 603   virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
 604                             const char *Code) const;
 605
 606   /// Print the MachineOperand as a symbol. Targets with complex handling of
 607   /// symbol references should override the base implementation.
 608   virtual void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS);
 609
 610   /// Print the specified operand of MI, an INLINEASM instruction, using the
 611   /// specified assembler variant.  Targets should override this to format as
 612   /// appropriate.  This method can return true if the operand is erroneous.
 613   virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 614                                const char *ExtraCode, raw_ostream &OS);
 615
 616   /// Print the specified operand of MI, an INLINEASM instruction, using the
 617   /// specified assembler variant as an address. Targets should override this to
 618   /// format as appropriate.  This method can return true if the operand is
 619   /// erroneous.
 620   virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 621                                      const char *ExtraCode, raw_ostream &OS);
 622
 623   /// Let the target do anything it needs to do before emitting inlineasm.
 624   /// \p StartInfo - the subtarget info before parsing inline asm
 625   virtual void emitInlineAsmStart() const;
 626
 627   /// Let the target do anything it needs to do after emitting inlineasm.
 628   /// This callback can be used restore the original mode in case the
 629   /// inlineasm contains directives to switch modes.
 630   /// \p StartInfo - the original subtarget info before inline asm
 631   /// \p EndInfo   - the final subtarget info after parsing the inline asm,
 632   ///                or NULL if the value is unknown.
 633   virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
 634                                 const MCSubtargetInfo *EndInfo) const;
 635
 636   /// This emits visibility information about symbol, if this is supported by
 637   /// the target.
 638   void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
 639                       bool IsDefinition = true) const;
 640
 641   /// This emits linkage information about \p GVSym based on \p GV, if this is
 642   /// supported by the target.
 643   void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
 644
 645   /// Return the alignment for the specified \p GV.
 646   static Align getGVAlignment(const GlobalValue *GV, const DataLayout &DL,
 647                               Align InAlign = Align::None());
 648
 649 private:
 650   /// Private state for PrintSpecial()
 651   // Assign a unique ID to this machine instruction.
 652   mutable const MachineInstr *LastMI = nullptr;
 653   mutable unsigned LastFn = 0;
 654   mutable unsigned Counter = ~0U;
 655
 656   /// This method emits the header for the current function.
 657   virtual void EmitFunctionHeader();
 658
 659   /// Emit a blob of inline asm to the output streamer.
 660   void
 661   EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
 662                 const MCTargetOptions &MCOptions,
 663                 const MDNode *LocMDNode = nullptr,
 664                 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
 665
 666   /// This method formats and emits the specified machine instruction that is an
 667   /// inline asm.
 668   void EmitInlineAsm(const MachineInstr *MI) const;
 669
 670   /// Add inline assembly info to the diagnostics machinery, so we can
 671   /// emit file and position info. Returns SrcMgr memory buffer position.
 672   unsigned addInlineAsmDiagBuffer(StringRef AsmStr,
 673                                   const MDNode *LocMDNode) const;
 674
 675   //===------------------------------------------------------------------===//
 676   // Internal Implementation Details
 677   //===------------------------------------------------------------------===//
 678
 679   void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
 680                           const MachineBasicBlock *MBB, unsigned uid) const;
 681   void EmitLLVMUsedList(const ConstantArray *InitList);
 682   /// Emit llvm.ident metadata in an '.ident' directive.
 683   void EmitModuleIdents(Module &M);
 684   /// Emit bytes for llvm.commandline metadata.
 685   void EmitModuleCommandLines(Module &M);
 686   void EmitXXStructorList(const DataLayout &DL, const Constant *List,
 687                           bool isCtor);
 688
 689   GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &S);
 690   /// Emit GlobalAlias or GlobalIFunc.
 691   void emitGlobalIndirectSymbol(Module &M, const GlobalIndirectSymbol &GIS);
 692   void setupCodePaddingContext(const MachineBasicBlock &MBB,
 693                                MCCodePaddingContext &Context) const;
 694 };
 695
 696 } // end namespace llvm
 697
 698 #endif // LLVM_CODEGEN_ASMPRINTER_H