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. 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(llvm::Align Align, 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.
 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.
 388   virtual void EmitEndOfAsmFile(Module &) {}
 389
 390   /// Targets can override this to emit stuff before the first basic block in
 391   /// the function.
 392   virtual void EmitFunctionBodyStart() {}
 393
 394   /// Targets can override this to emit stuff after the last basic block in the
 395   /// function.
 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);
 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.
 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.
 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, unsigned PadTo = 0) 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.
 541   void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
 542     emitDwarfStringOffset(S.getEntry());
 543   }
 544
 545   /// Emit reference to a call site with a specified encoding
 546   void EmitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo,
 547                           unsigned Encoding) const;
 548   /// Emit an integer value corresponding to the call site encoding
 549   void EmitCallSiteValue(uint64_t Value, unsigned Encoding) const;
 550
 551   /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
 552   virtual unsigned getISAEncoding() { return 0; }
 553
 554   /// Emit the directive and value for debug thread local expression
 555   ///
 556   /// \p Value - The value to emit.
 557   /// \p Size - The size of the integer (in bytes) to emit.
 558   virtual void EmitDebugValue(const MCExpr *Value, unsigned Size) const;
 559
 560   //===------------------------------------------------------------------===//
 561   // Dwarf Lowering Routines
 562   //===------------------------------------------------------------------===//
 563
 564   /// Emit frame instruction to describe the layout of the frame.
 565   void emitCFIInstruction(const MCCFIInstruction &Inst) const;
 566
 567   /// Emit Dwarf abbreviation table.
 568   template <typename T> void emitDwarfAbbrevs(const T &Abbrevs) const {
 569     // For each abbreviation.
 570     for (const auto &Abbrev : Abbrevs)
 571       emitDwarfAbbrev(*Abbrev);
 572
 573     // Mark end of abbreviations.
 574     EmitULEB128(0, "EOM(3)");
 575   }
 576
 577   void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const;
 578
 579   /// Recursively emit Dwarf DIE tree.
 580   void emitDwarfDIE(const DIE &Die) const;
 581
 582   //===------------------------------------------------------------------===//
 583   // Inline Asm Support
 584   //===------------------------------------------------------------------===//
 585
 586   // These are hooks that targets can override to implement inline asm
 587   // support.  These should probably be moved out of AsmPrinter someday.
 588
 589   /// Print information related to the specified machine instr that is
 590   /// independent of the operand, and may be independent of the instr itself.
 591   /// This can be useful for portably encoding the comment character or other
 592   /// bits of target-specific knowledge into the asmstrings.  The syntax used is
 593   /// ${:comment}.  Targets can override this to add support for their own
 594   /// strange codes.
 595   virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
 596                             const char *Code) const;
 597
 598   /// Print the MachineOperand as a symbol. Targets with complex handling of
 599   /// symbol references should override the base implementation.
 600   virtual void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS);
 601
 602   /// Print the specified operand of MI, an INLINEASM instruction, using the
 603   /// specified assembler variant.  Targets should override this to format as
 604   /// appropriate.  This method can return true if the operand is erroneous.
 605   virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 606                                const char *ExtraCode, raw_ostream &OS);
 607
 608   /// Print the specified operand of MI, an INLINEASM instruction, using the
 609   /// specified assembler variant as an address. Targets should override this to
 610   /// format as appropriate.  This method can return true if the operand is
 611   /// erroneous.
 612   virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 613                                      const char *ExtraCode, raw_ostream &OS);
 614
 615   /// Let the target do anything it needs to do before emitting inlineasm.
 616   /// \p StartInfo - the subtarget info before parsing inline asm
 617   virtual void emitInlineAsmStart() const;
 618
 619   /// Let the target do anything it needs to do after emitting inlineasm.
 620   /// This callback can be used restore the original mode in case the
 621   /// inlineasm contains directives to switch modes.
 622   /// \p StartInfo - the original subtarget info before inline asm
 623   /// \p EndInfo   - the final subtarget info after parsing the inline asm,
 624   ///                or NULL if the value is unknown.
 625   virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
 626                                 const MCSubtargetInfo *EndInfo) const;
 627
 628   /// This emits visibility information about symbol, if this is supported by
 629   /// the target.
 630   void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
 631                       bool IsDefinition = true) const;
 632
 633   /// This emits linkage information about \p GVSym based on \p GV, if this is
 634   /// supported by the target.
 635   void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
 636
 637   /// Return the alignment for the specified \p GV.
 638   static llvm::Align getGVAlignment(const GlobalValue *GV, const DataLayout &DL,
 639                                     llvm::Align InAlign = llvm::Align(1));
 640
 641 private:
 642   /// Private state for PrintSpecial()
 643   // Assign a unique ID to this machine instruction.
 644   mutable const MachineInstr *LastMI = nullptr;
 645   mutable unsigned LastFn = 0;
 646   mutable unsigned Counter = ~0U;
 647
 648   /// This method emits the header for the current function.
 649   virtual void EmitFunctionHeader();
 650
 651   /// Emit a blob of inline asm to the output streamer.
 652   void
 653   EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
 654                 const MCTargetOptions &MCOptions,
 655                 const MDNode *LocMDNode = nullptr,
 656                 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
 657
 658   /// This method formats and emits the specified machine instruction that is an
 659   /// inline asm.
 660   void EmitInlineAsm(const MachineInstr *MI) const;
 661
 662   /// Add inline assembly info to the diagnostics machinery, so we can
 663   /// emit file and position info. Returns SrcMgr memory buffer position.
 664   unsigned addInlineAsmDiagBuffer(StringRef AsmStr,
 665                                   const MDNode *LocMDNode) const;
 666
 667   //===------------------------------------------------------------------===//
 668   // Internal Implementation Details
 669   //===------------------------------------------------------------------===//
 670
 671   void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
 672                           const MachineBasicBlock *MBB, unsigned uid) const;
 673   void EmitLLVMUsedList(const ConstantArray *InitList);
 674   /// Emit llvm.ident metadata in an '.ident' directive.
 675   void EmitModuleIdents(Module &M);
 676   /// Emit bytes for llvm.commandline metadata.
 677   void EmitModuleCommandLines(Module &M);
 678   void EmitXXStructorList(const DataLayout &DL, const Constant *List,
 679                           bool isCtor);
 680
 681   GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &S);
 682   /// Emit GlobalAlias or GlobalIFunc.
 683   void emitGlobalIndirectSymbol(Module &M, const GlobalIndirectSymbol &GIS);
 684   void setupCodePaddingContext(const MachineBasicBlock &MBB,
 685                                MCCodePaddingContext &Context) const;
 686 };
 687
 688 } // end namespace llvm
 689
 690 #endif // LLVM_CODEGEN_ASMPRINTER_H