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 used to represent the start of the current function for the
 115   /// purpose of calculating its size (e.g. using the .size directive). By
 116   /// default, this is equal to CurrentFnSym.
 117   MCSymbol *CurrentFnSymForSize = nullptr;
 118
 119   /// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of
 120   /// its number of uses by other globals.
 121   using GOTEquivUsePair = std::pair<const GlobalVariable *, unsigned>;
 122   MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs;
 123
 124 private:
 125   MCSymbol *CurrentFnBegin = nullptr;
 126   MCSymbol *CurrentFnEnd = nullptr;
 127   MCSymbol *CurExceptionSym = nullptr;
 128
 129   // The garbage collection metadata printer table.
 130   void *GCMetadataPrinters = nullptr; // Really a DenseMap.
 131
 132   /// Emit comments in assembly output if this is true.
 133   bool VerboseAsm;
 134
 135   static char ID;
 136
 137 protected:
 138   /// Protected struct HandlerInfo and Handlers permit target extended
 139   /// AsmPrinter adds their own handlers.
 140   struct HandlerInfo {
 141     std::unique_ptr<AsmPrinterHandler> Handler;
 142     const char *TimerName;
 143     const char *TimerDescription;
 144     const char *TimerGroupName;
 145     const char *TimerGroupDescription;
 146
 147     HandlerInfo(std::unique_ptr<AsmPrinterHandler> Handler,
 148                 const char *TimerName, const char *TimerDescription,
 149                 const char *TimerGroupName, const char *TimerGroupDescription)
 150         : Handler(std::move(Handler)), TimerName(TimerName),
 151           TimerDescription(TimerDescription), TimerGroupName(TimerGroupName),
 152           TimerGroupDescription(TimerGroupDescription) {}
 153   };
 154
 155   /// A vector of all debug/EH info emitters we should use. This vector
 156   /// maintains ownership of the emitters.
 157   SmallVector<HandlerInfo, 1> Handlers;
 158
 159 public:
 160   struct SrcMgrDiagInfo {
 161     SourceMgr SrcMgr;
 162     std::vector<const MDNode *> LocInfos;
 163     LLVMContext::InlineAsmDiagHandlerTy DiagHandler;
 164     void *DiagContext;
 165   };
 166
 167 private:
 168   /// If generated on the fly this own the instance.
 169   std::unique_ptr<MachineDominatorTree> OwnedMDT;
 170
 171   /// If generated on the fly this own the instance.
 172   std::unique_ptr<MachineLoopInfo> OwnedMLI;
 173
 174   /// Structure for generating diagnostics for inline assembly. Only initialised
 175   /// when necessary.
 176   mutable std::unique_ptr<SrcMgrDiagInfo> DiagInfo;
 177
 178   /// If the target supports dwarf debug info, this pointer is non-null.
 179   DwarfDebug *DD = nullptr;
 180
 181   /// If the current module uses dwarf CFI annotations strictly for debugging.
 182   bool isCFIMoveForDebugging = false;
 183
 184 protected:
 185   explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
 186
 187 public:
 188   ~AsmPrinter() override;
 189
 190   DwarfDebug *getDwarfDebug() { return DD; }
 191   DwarfDebug *getDwarfDebug() const { return DD; }
 192
 193   uint16_t getDwarfVersion() const;
 194   void setDwarfVersion(uint16_t Version);
 195
 196   bool isPositionIndependent() const;
 197
 198   /// Return true if assembly output should contain comments.
 199   bool isVerbose() const { return VerboseAsm; }
 200
 201   /// Return a unique ID for the current function.
 202   unsigned getFunctionNumber() const;
 203
 204   /// Return symbol for the function pseudo stack if the stack frame is not a
 205   /// register based.
 206   virtual const MCSymbol *getFunctionFrameSymbol() const { return nullptr; }
 207
 208   MCSymbol *getFunctionBegin() const { return CurrentFnBegin; }
 209   MCSymbol *getFunctionEnd() const { return CurrentFnEnd; }
 210   MCSymbol *getCurExceptionSym();
 211
 212   /// Return information about object file lowering.
 213   const TargetLoweringObjectFile &getObjFileLowering() const;
 214
 215   /// Return information about data layout.
 216   const DataLayout &getDataLayout() const;
 217
 218   /// Return the pointer size from the TargetMachine
 219   unsigned getPointerSize() const;
 220
 221   /// Return information about subtarget.
 222   const MCSubtargetInfo &getSubtargetInfo() const;
 223
 224   void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
 225
 226   /// Emits inital debug location directive.
 227   void emitInitialRawDwarfLocDirective(const MachineFunction &MF);
 228
 229   /// Return the current section we are emitting to.
 230   const MCSection *getCurrentSection() const;
 231
 232   void getNameWithPrefix(SmallVectorImpl<char> &Name,
 233                          const GlobalValue *GV) const;
 234
 235   MCSymbol *getSymbol(const GlobalValue *GV) const;
 236
 237   //===------------------------------------------------------------------===//
 238   // XRay instrumentation implementation.
 239   //===------------------------------------------------------------------===//
 240 public:
 241   // This describes the kind of sled we're storing in the XRay table.
 242   enum class SledKind : uint8_t {
 243     FUNCTION_ENTER = 0,
 244     FUNCTION_EXIT = 1,
 245     TAIL_CALL = 2,
 246     LOG_ARGS_ENTER = 3,
 247     CUSTOM_EVENT = 4,
 248     TYPED_EVENT = 5,
 249   };
 250
 251   // The table will contain these structs that point to the sled, the function
 252   // containing the sled, and what kind of sled (and whether they should always
 253   // be instrumented). We also use a version identifier that the runtime can use
 254   // to decide what to do with the sled, depending on the version of the sled.
 255   struct XRayFunctionEntry {
 256     const MCSymbol *Sled;
 257     const MCSymbol *Function;
 258     SledKind Kind;
 259     bool AlwaysInstrument;
 260     const class Function *Fn;
 261     uint8_t Version;
 262
 263     void emit(int, MCStreamer *, const MCSymbol *) const;
 264   };
 265
 266   // All the sleds to be emitted.
 267   SmallVector<XRayFunctionEntry, 4> Sleds;
 268
 269   // A unique ID used for ELF sections associated with a particular function.
 270   unsigned XRayFnUniqueID = 0;
 271
 272   // Helper function to record a given XRay sled.
 273   void recordSled(MCSymbol *Sled, const MachineInstr &MI, SledKind Kind,
 274                   uint8_t Version = 0);
 275
 276   /// Emit a table with all XRay instrumentation points.
 277   void emitXRayTable();
 278
 279   //===------------------------------------------------------------------===//
 280   // MachineFunctionPass Implementation.
 281   //===------------------------------------------------------------------===//
 282
 283   /// Record analysis usage.
 284   void getAnalysisUsage(AnalysisUsage &AU) const override;
 285
 286   /// Set up the AsmPrinter when we are working on a new module. If your pass
 287   /// overrides this, it must make sure to explicitly call this implementation.
 288   bool doInitialization(Module &M) override;
 289
 290   /// Shut down the asmprinter. If you override this in your pass, you must make
 291   /// sure to call it explicitly.
 292   bool doFinalization(Module &M) override;
 293
 294   /// Emit the specified function out to the OutStreamer.
 295   bool runOnMachineFunction(MachineFunction &MF) override {
 296     SetupMachineFunction(MF);
 297     EmitFunctionBody();
 298     return false;
 299   }
 300
 301   //===------------------------------------------------------------------===//
 302   // Coarse grained IR lowering routines.
 303   //===------------------------------------------------------------------===//
 304
 305   /// This should be called when a new MachineFunction is being processed from
 306   /// runOnMachineFunction.
 307   void SetupMachineFunction(MachineFunction &MF);
 308
 309   /// This method emits the body and trailer for a function.
 310   void EmitFunctionBody();
 311
 312   void emitCFIInstruction(const MachineInstr &MI);
 313
 314   void emitFrameAlloc(const MachineInstr &MI);
 315
 316   void emitStackSizeSection(const MachineFunction &MF);
 317
 318   void emitRemarksSection(Module &M);
 319
 320   enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
 321   CFIMoveType needsCFIMoves() const;
 322
 323   /// Returns false if needsCFIMoves() == CFI_M_EH for any function
 324   /// in the module.
 325   bool needsOnlyDebugCFIMoves() const { return isCFIMoveForDebugging; }
 326
 327   bool needsSEHMoves();
 328
 329   /// Print to the current output stream assembly representations of the
 330   /// constants in the constant pool MCP. This is used to print out constants
 331   /// which have been "spilled to memory" by the code generator.
 332   virtual void EmitConstantPool();
 333
 334   /// Print assembly representations of the jump tables used by the current
 335   /// function to the current output stream.
 336   virtual void EmitJumpTableInfo();
 337
 338   /// Emit the specified global variable to the .s file.
 339   virtual void EmitGlobalVariable(const GlobalVariable *GV);
 340
 341   /// Check to see if the specified global is a special global used by LLVM. If
 342   /// so, emit it and return true, otherwise do nothing and return false.
 343   bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
 344
 345   /// Emit an alignment directive to the specified power of two boundary. For
 346   /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
 347   /// global value is specified, and if that global has an explicit alignment
 348   /// requested, it will override the alignment request if required for
 349   /// correctness.
 350   void EmitAlignment(unsigned NumBits, const GlobalObject *GV = nullptr) const;
 351
 352   /// Lower the specified LLVM Constant to an MCExpr.
 353   virtual const MCExpr *lowerConstant(const Constant *CV);
 354
 355   /// Print a general LLVM constant to the .s file.
 356   void EmitGlobalConstant(const DataLayout &DL, const Constant *CV);
 357
 358   /// Unnamed constant global variables solely contaning a pointer to
 359   /// another globals variable act like a global variable "proxy", or GOT
 360   /// equivalents, i.e., it's only used to hold the address of the latter. One
 361   /// optimization is to replace accesses to these proxies by using the GOT
 362   /// entry for the final global instead. Hence, we select GOT equivalent
 363   /// candidates among all the module global variables, avoid emitting them
 364   /// unnecessarily and finally replace references to them by pc relative
 365   /// accesses to GOT entries.
 366   void computeGlobalGOTEquivs(Module &M);
 367
 368   /// Constant expressions using GOT equivalent globals may not be
 369   /// eligible for PC relative GOT entry conversion, in such cases we need to
 370   /// emit the proxies we previously omitted in EmitGlobalVariable.
 371   void emitGlobalGOTEquivs();
 372
 373   /// Emit the stack maps.
 374   void emitStackMaps(StackMaps &SM);
 375
 376   //===------------------------------------------------------------------===//
 377   // Overridable Hooks
 378   //===------------------------------------------------------------------===//
 379
 380   // Targets can, or in the case of EmitInstruction, must implement these to
 381   // customize output.
 382
 383   /// This virtual method can be overridden by targets that want to emit
 384   /// something at the start of their file.
 385   virtual void EmitStartOfAsmFile(Module &) {}
 386
 387   /// This virtual method can be overridden by targets that want to emit
 388   /// something at the end of their file.
 389   virtual void EmitEndOfAsmFile(Module &) {}
 390
 391   /// Targets can override this to emit stuff before the first basic block in
 392   /// the function.
 393   virtual void EmitFunctionBodyStart() {}
 394
 395   /// Targets can override this to emit stuff after the last basic block in the
 396   /// function.
 397   virtual void EmitFunctionBodyEnd() {}
 398
 399   /// Targets can override this to emit stuff at the start of a basic block.
 400   /// By default, this method prints the label for the specified
 401   /// MachineBasicBlock, an alignment (if present) and a comment describing it
 402   /// if appropriate.
 403   virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB);
 404
 405   /// Targets can override this to emit stuff at the end of a basic block.
 406   virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB);
 407
 408   /// Targets should implement this to emit instructions.
 409   virtual void EmitInstruction(const MachineInstr *) {
 410     llvm_unreachable("EmitInstruction not implemented");
 411   }
 412
 413   /// Return the symbol for the specified constant pool entry.
 414   virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
 415
 416   virtual void EmitFunctionEntryLabel();
 417
 418   virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
 419
 420   /// Targets can override this to change how global constants that are part of
 421   /// a C++ static/global constructor list are emitted.
 422   virtual void EmitXXStructor(const DataLayout &DL, const Constant *CV) {
 423     EmitGlobalConstant(DL, CV);
 424   }
 425
 426   /// Return true if the basic block has exactly one predecessor and the control
 427   /// transfer mechanism between the predecessor and this block is a
 428   /// fall-through.
 429   virtual bool
 430   isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
 431
 432   /// Targets can override this to customize the output of IMPLICIT_DEF
 433   /// instructions in verbose mode.
 434   virtual void emitImplicitDef(const MachineInstr *MI) const;
 435
 436   //===------------------------------------------------------------------===//
 437   // Symbol Lowering Routines.
 438   //===------------------------------------------------------------------===//
 439
 440   MCSymbol *createTempSymbol(const Twine &Name) const;
 441
 442   /// Return the MCSymbol for a private symbol with global value name as its
 443   /// base, with the specified suffix.
 444   MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
 445                                          StringRef Suffix) const;
 446
 447   /// Return the MCSymbol for the specified ExternalSymbol.
 448   MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
 449
 450   /// Return the symbol for the specified jump table entry.
 451   MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
 452
 453   /// Return the symbol for the specified jump table .set
 454   /// FIXME: privatize to AsmPrinter.
 455   MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
 456
 457   /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
 458   /// basic block.
 459   MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
 460   MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
 461
 462   //===------------------------------------------------------------------===//
 463   // Emission Helper Routines.
 464   //===------------------------------------------------------------------===//
 465
 466   /// This is just convenient handler for printing offsets.
 467   void printOffset(int64_t Offset, raw_ostream &OS) const;
 468
 469   /// Emit a byte directive and value.
 470   void emitInt8(int Value) const;
 471
 472   /// Emit a short directive and value.
 473   void emitInt16(int Value) const;
 474
 475   /// Emit a long directive and value.
 476   void emitInt32(int Value) const;
 477
 478   /// Emit a long long directive and value.
 479   void emitInt64(uint64_t Value) const;
 480
 481   /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
 482   /// is specified by Size and Hi/Lo specify the labels.  This implicitly uses
 483   /// .set if it is available.
 484   void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
 485                            unsigned Size) const;
 486
 487   /// Emit something like ".uleb128 Hi-Lo".
 488   void EmitLabelDifferenceAsULEB128(const MCSymbol *Hi,
 489                                     const MCSymbol *Lo) const;
 490
 491   /// Emit something like ".long Label+Offset" where the size in bytes of the
 492   /// directive is specified by Size and Label specifies the label.  This
 493   /// implicitly uses .set if it is available.
 494   void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
 495                            unsigned Size, bool IsSectionRelative = false) const;
 496
 497   /// Emit something like ".long Label" where the size in bytes of the directive
 498   /// is specified by Size and Label specifies the label.
 499   void EmitLabelReference(const MCSymbol *Label, unsigned Size,
 500                           bool IsSectionRelative = false) const {
 501     EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
 502   }
 503
 504   /// Emit something like ".long Label + Offset".
 505   void EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const;
 506
 507   //===------------------------------------------------------------------===//
 508   // Dwarf Emission Helper Routines
 509   //===------------------------------------------------------------------===//
 510
 511   /// Emit the specified signed leb128 value.
 512   void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
 513
 514   /// Emit the specified unsigned leb128 value.
 515   void EmitULEB128(uint64_t Value, const char *Desc = nullptr, unsigned PadTo = 0) const;
 516
 517   /// Emit a .byte 42 directive that corresponds to an encoding.  If verbose
 518   /// assembly output is enabled, we output comments describing the encoding.
 519   /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
 520   void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
 521
 522   /// Return the size of the encoding in bytes.
 523   unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
 524
 525   /// Emit reference to a ttype global with a specified encoding.
 526   void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
 527
 528   /// Emit a reference to a symbol for use in dwarf. Different object formats
 529   /// represent this in different ways. Some use a relocation others encode
 530   /// the label offset in its section.
 531   void emitDwarfSymbolReference(const MCSymbol *Label,
 532                                 bool ForceOffset = false) const;
 533
 534   /// Emit the 4-byte offset of a string from the start of its section.
 535   ///
 536   /// When possible, emit a DwarfStringPool section offset without any
 537   /// relocations, and without using the symbol.  Otherwise, defers to \a
 538   /// emitDwarfSymbolReference().
 539   void emitDwarfStringOffset(DwarfStringPoolEntry S) const;
 540
 541   /// Emit the 4-byte offset of a string from the start of its section.
 542   void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
 543     emitDwarfStringOffset(S.getEntry());
 544   }
 545
 546   /// Emit reference to a call site with a specified encoding
 547   void EmitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo,
 548                           unsigned Encoding) const;
 549   /// Emit an integer value corresponding to the call site encoding
 550   void EmitCallSiteValue(uint64_t Value, unsigned Encoding) const;
 551
 552   /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
 553   virtual unsigned getISAEncoding() { return 0; }
 554
 555   /// Emit the directive and value for debug thread local expression
 556   ///
 557   /// \p Value - The value to emit.
 558   /// \p Size - The size of the integer (in bytes) to emit.
 559   virtual void EmitDebugValue(const MCExpr *Value, unsigned Size) const;
 560
 561   //===------------------------------------------------------------------===//
 562   // Dwarf Lowering Routines
 563   //===------------------------------------------------------------------===//
 564
 565   /// Emit frame instruction to describe the layout of the frame.
 566   void emitCFIInstruction(const MCCFIInstruction &Inst) const;
 567
 568   /// Emit Dwarf abbreviation table.
 569   template <typename T> void emitDwarfAbbrevs(const T &Abbrevs) const {
 570     // For each abbreviation.
 571     for (const auto &Abbrev : Abbrevs)
 572       emitDwarfAbbrev(*Abbrev);
 573
 574     // Mark end of abbreviations.
 575     EmitULEB128(0, "EOM(3)");
 576   }
 577
 578   void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const;
 579
 580   /// Recursively emit Dwarf DIE tree.
 581   void emitDwarfDIE(const DIE &Die) const;
 582
 583   //===------------------------------------------------------------------===//
 584   // Inline Asm Support
 585   //===------------------------------------------------------------------===//
 586
 587   // These are hooks that targets can override to implement inline asm
 588   // support.  These should probably be moved out of AsmPrinter someday.
 589
 590   /// Print information related to the specified machine instr that is
 591   /// independent of the operand, and may be independent of the instr itself.
 592   /// This can be useful for portably encoding the comment character or other
 593   /// bits of target-specific knowledge into the asmstrings.  The syntax used is
 594   /// ${:comment}.  Targets can override this to add support for their own
 595   /// strange codes.
 596   virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
 597                             const char *Code) const;
 598
 599   /// Print the MachineOperand as a symbol. Targets with complex handling of
 600   /// symbol references should override the base implementation.
 601   virtual void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS);
 602
 603   /// Print the specified operand of MI, an INLINEASM instruction, using the
 604   /// specified assembler variant.  Targets should override this to format as
 605   /// appropriate.  This method can return true if the operand is erroneous.
 606   virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 607                                const char *ExtraCode, raw_ostream &OS);
 608
 609   /// Print the specified operand of MI, an INLINEASM instruction, using the
 610   /// specified assembler variant as an address. Targets should override this to
 611   /// format as appropriate.  This method can return true if the operand is
 612   /// erroneous.
 613   virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 614                                      const char *ExtraCode, raw_ostream &OS);
 615
 616   /// Let the target do anything it needs to do before emitting inlineasm.
 617   /// \p StartInfo - the subtarget info before parsing inline asm
 618   virtual void emitInlineAsmStart() const;
 619
 620   /// Let the target do anything it needs to do after emitting inlineasm.
 621   /// This callback can be used restore the original mode in case the
 622   /// inlineasm contains directives to switch modes.
 623   /// \p StartInfo - the original subtarget info before inline asm
 624   /// \p EndInfo   - the final subtarget info after parsing the inline asm,
 625   ///                or NULL if the value is unknown.
 626   virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
 627                                 const MCSubtargetInfo *EndInfo) const;
 628
 629   /// This emits visibility information about symbol, if this is supported by
 630   /// the target.
 631   void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
 632                       bool IsDefinition = true) const;
 633
 634   /// This emits linkage information about \p GVSym based on \p GV, if this is
 635   /// supported by the target.
 636   void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
 637
 638   /// Return the alignment in log2 form for the specified \p GV.
 639   static unsigned getGVAlignmentLog2(const GlobalValue *GV,
 640                                      const DataLayout &DL,
 641                                      unsigned InBits = 0);
 642
 643 private:
 644   /// Private state for PrintSpecial()
 645   // Assign a unique ID to this machine instruction.
 646   mutable const MachineInstr *LastMI = nullptr;
 647   mutable unsigned LastFn = 0;
 648   mutable unsigned Counter = ~0U;
 649
 650   /// This method emits the header for the current function.
 651   virtual void EmitFunctionHeader();
 652
 653   /// Emit a blob of inline asm to the output streamer.
 654   void
 655   EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
 656                 const MCTargetOptions &MCOptions,
 657                 const MDNode *LocMDNode = nullptr,
 658                 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
 659
 660   /// This method formats and emits the specified machine instruction that is an
 661   /// inline asm.
 662   void EmitInlineAsm(const MachineInstr *MI) const;
 663
 664   /// Add inline assembly info to the diagnostics machinery, so we can
 665   /// emit file and position info. Returns SrcMgr memory buffer position.
 666   unsigned addInlineAsmDiagBuffer(StringRef AsmStr,
 667                                   const MDNode *LocMDNode) const;
 668
 669   //===------------------------------------------------------------------===//
 670   // Internal Implementation Details
 671   //===------------------------------------------------------------------===//
 672
 673   void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
 674                           const MachineBasicBlock *MBB, unsigned uid) const;
 675   void EmitLLVMUsedList(const ConstantArray *InitList);
 676   /// Emit llvm.ident metadata in an '.ident' directive.
 677   void EmitModuleIdents(Module &M);
 678   /// Emit bytes for llvm.commandline metadata.
 679   void EmitModuleCommandLines(Module &M);
 680   void EmitXXStructorList(const DataLayout &DL, const Constant *List,
 681                           bool isCtor);
 682
 683   GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &S);
 684   /// Emit GlobalAlias or GlobalIFunc.
 685   void emitGlobalIndirectSymbol(Module &M, const GlobalIndirectSymbol &GIS);
 686   void setupCodePaddingContext(const MachineBasicBlock &MBB,
 687                                MCCodePaddingContext &Context) const;
 688 };
 689
 690 } // end namespace llvm
 691
 692 #endif // LLVM_CODEGEN_ASMPRINTER_H