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  1. //===- MCStreamer.h - High-level Streaming Machine Code Output --*- 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 declares the MCStreamer class.
  10. //
  11. //===----------------------------------------------------------------------===//
  12.  
  13. #ifndef LLVM_MC_MCSTREAMER_H
  14. #define LLVM_MC_MCSTREAMER_H
  15.  
  16. #include "llvm/ADT/ArrayRef.h"
  17. #include "llvm/ADT/DenseMap.h"
  18. #include "llvm/ADT/SmallVector.h"
  19. #include "llvm/ADT/StringRef.h"
  20. #include "llvm/MC/MCDirectives.h"
  21. #include "llvm/MC/MCDwarf.h"
  22. #include "llvm/MC/MCLinkerOptimizationHint.h"
  23. #include "llvm/MC/MCPseudoProbe.h"
  24. #include "llvm/MC/MCWinEH.h"
  25. #include "llvm/Support/ARMTargetParser.h"
  26. #include "llvm/Support/Error.h"
  27. #include "llvm/Support/MD5.h"
  28. #include "llvm/Support/SMLoc.h"
  29. #include "llvm/Support/VersionTuple.h"
  30. #include <cassert>
  31. #include <cstdint>
  32. #include <memory>
  33. #include <optional>
  34. #include <string>
  35. #include <utility>
  36. #include <vector>
  37.  
  38. namespace llvm {
  39.  
  40. class APInt;
  41. class AssemblerConstantPools;
  42. class MCAsmBackend;
  43. class MCAssembler;
  44. class MCContext;
  45. class MCExpr;
  46. class MCFragment;
  47. class MCInst;
  48. class MCInstPrinter;
  49. class MCRegister;
  50. class MCSection;
  51. class MCStreamer;
  52. class MCSubtargetInfo;
  53. class MCSymbol;
  54. class MCSymbolRefExpr;
  55. class Triple;
  56. class Twine;
  57. class raw_ostream;
  58.  
  59. namespace codeview {
  60. struct DefRangeRegisterRelHeader;
  61. struct DefRangeSubfieldRegisterHeader;
  62. struct DefRangeRegisterHeader;
  63. struct DefRangeFramePointerRelHeader;
  64. }
  65.  
  66. using MCSectionSubPair = std::pair<MCSection *, const MCExpr *>;
  67.  
  68. /// Target specific streamer interface. This is used so that targets can
  69. /// implement support for target specific assembly directives.
  70. ///
  71. /// If target foo wants to use this, it should implement 3 classes:
  72. /// * FooTargetStreamer : public MCTargetStreamer
  73. /// * FooTargetAsmStreamer : public FooTargetStreamer
  74. /// * FooTargetELFStreamer : public FooTargetStreamer
  75. ///
  76. /// FooTargetStreamer should have a pure virtual method for each directive. For
  77. /// example, for a ".bar symbol_name" directive, it should have
  78. /// virtual emitBar(const MCSymbol &Symbol) = 0;
  79. ///
  80. /// The FooTargetAsmStreamer and FooTargetELFStreamer classes implement the
  81. /// method. The assembly streamer just prints ".bar symbol_name". The object
  82. /// streamer does whatever is needed to implement .bar in the object file.
  83. ///
  84. /// In the assembly printer and parser the target streamer can be used by
  85. /// calling getTargetStreamer and casting it to FooTargetStreamer:
  86. ///
  87. /// MCTargetStreamer &TS = OutStreamer.getTargetStreamer();
  88. /// FooTargetStreamer &ATS = static_cast<FooTargetStreamer &>(TS);
  89. ///
  90. /// The base classes FooTargetAsmStreamer and FooTargetELFStreamer should
  91. /// *never* be treated differently. Callers should always talk to a
  92. /// FooTargetStreamer.
  93. class MCTargetStreamer {
  94. protected:
  95.   MCStreamer &Streamer;
  96.  
  97. public:
  98.   MCTargetStreamer(MCStreamer &S);
  99.   virtual ~MCTargetStreamer();
  100.  
  101.   MCStreamer &getStreamer() { return Streamer; }
  102.  
  103.   // Allow a target to add behavior to the EmitLabel of MCStreamer.
  104.   virtual void emitLabel(MCSymbol *Symbol);
  105.   // Allow a target to add behavior to the emitAssignment of MCStreamer.
  106.   virtual void emitAssignment(MCSymbol *Symbol, const MCExpr *Value);
  107.  
  108.   virtual void prettyPrintAsm(MCInstPrinter &InstPrinter, uint64_t Address,
  109.                               const MCInst &Inst, const MCSubtargetInfo &STI,
  110.                               raw_ostream &OS);
  111.  
  112.   virtual void emitDwarfFileDirective(StringRef Directive);
  113.  
  114.   /// Update streamer for a new active section.
  115.   ///
  116.   /// This is called by popSection and switchSection, if the current
  117.   /// section changes.
  118.   virtual void changeSection(const MCSection *CurSection, MCSection *Section,
  119.                              const MCExpr *SubSection, raw_ostream &OS);
  120.  
  121.   virtual void emitValue(const MCExpr *Value);
  122.  
  123.   /// Emit the bytes in \p Data into the output.
  124.   ///
  125.   /// This is used to emit bytes in \p Data as sequence of .byte directives.
  126.   virtual void emitRawBytes(StringRef Data);
  127.  
  128.   virtual void emitConstantPools();
  129.  
  130.   virtual void finish();
  131. };
  132.  
  133. // FIXME: declared here because it is used from
  134. // lib/CodeGen/AsmPrinter/ARMException.cpp.
  135. class ARMTargetStreamer : public MCTargetStreamer {
  136. public:
  137.   ARMTargetStreamer(MCStreamer &S);
  138.   ~ARMTargetStreamer() override;
  139.  
  140.   virtual void emitFnStart();
  141.   virtual void emitFnEnd();
  142.   virtual void emitCantUnwind();
  143.   virtual void emitPersonality(const MCSymbol *Personality);
  144.   virtual void emitPersonalityIndex(unsigned Index);
  145.   virtual void emitHandlerData();
  146.   virtual void emitSetFP(unsigned FpReg, unsigned SpReg,
  147.                          int64_t Offset = 0);
  148.   virtual void emitMovSP(unsigned Reg, int64_t Offset = 0);
  149.   virtual void emitPad(int64_t Offset);
  150.   virtual void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
  151.                            bool isVector);
  152.   virtual void emitUnwindRaw(int64_t StackOffset,
  153.                              const SmallVectorImpl<uint8_t> &Opcodes);
  154.  
  155.   virtual void switchVendor(StringRef Vendor);
  156.   virtual void emitAttribute(unsigned Attribute, unsigned Value);
  157.   virtual void emitTextAttribute(unsigned Attribute, StringRef String);
  158.   virtual void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
  159.                                     StringRef StringValue = "");
  160.   virtual void emitFPU(unsigned FPU);
  161.   virtual void emitArch(ARM::ArchKind Arch);
  162.   virtual void emitArchExtension(uint64_t ArchExt);
  163.   virtual void emitObjectArch(ARM::ArchKind Arch);
  164.   void emitTargetAttributes(const MCSubtargetInfo &STI);
  165.   virtual void finishAttributeSection();
  166.   virtual void emitInst(uint32_t Inst, char Suffix = '\0');
  167.  
  168.   virtual void annotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE);
  169.  
  170.   virtual void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value);
  171.  
  172.   void emitConstantPools() override;
  173.  
  174.   virtual void emitARMWinCFIAllocStack(unsigned Size, bool Wide);
  175.   virtual void emitARMWinCFISaveRegMask(unsigned Mask, bool Wide);
  176.   virtual void emitARMWinCFISaveSP(unsigned Reg);
  177.   virtual void emitARMWinCFISaveFRegs(unsigned First, unsigned Last);
  178.   virtual void emitARMWinCFISaveLR(unsigned Offset);
  179.   virtual void emitARMWinCFIPrologEnd(bool Fragment);
  180.   virtual void emitARMWinCFINop(bool Wide);
  181.   virtual void emitARMWinCFIEpilogStart(unsigned Condition);
  182.   virtual void emitARMWinCFIEpilogEnd();
  183.   virtual void emitARMWinCFICustom(unsigned Opcode);
  184.  
  185.   /// Reset any state between object emissions, i.e. the equivalent of
  186.   /// MCStreamer's reset method.
  187.   virtual void reset();
  188.  
  189.   /// Callback used to implement the ldr= pseudo.
  190.   /// Add a new entry to the constant pool for the current section and return an
  191.   /// MCExpr that can be used to refer to the constant pool location.
  192.   const MCExpr *addConstantPoolEntry(const MCExpr *, SMLoc Loc);
  193.  
  194.   /// Callback used to implement the .ltorg directive.
  195.   /// Emit contents of constant pool for the current section.
  196.   void emitCurrentConstantPool();
  197.  
  198. private:
  199.   std::unique_ptr<AssemblerConstantPools> ConstantPools;
  200. };
  201.  
  202. /// Streaming machine code generation interface.
  203. ///
  204. /// This interface is intended to provide a programmatic interface that is very
  205. /// similar to the level that an assembler .s file provides.  It has callbacks
  206. /// to emit bytes, handle directives, etc.  The implementation of this interface
  207. /// retains state to know what the current section is etc.
  208. ///
  209. /// There are multiple implementations of this interface: one for writing out
  210. /// a .s file, and implementations that write out .o files of various formats.
  211. ///
  212. class MCStreamer {
  213.   MCContext &Context;
  214.   std::unique_ptr<MCTargetStreamer> TargetStreamer;
  215.  
  216.   std::vector<MCDwarfFrameInfo> DwarfFrameInfos;
  217.   MCDwarfFrameInfo *getCurrentDwarfFrameInfo();
  218.  
  219.   /// Similar to DwarfFrameInfos, but for SEH unwind info. Chained frames may
  220.   /// refer to each other, so use std::unique_ptr to provide pointer stability.
  221.   std::vector<std::unique_ptr<WinEH::FrameInfo>> WinFrameInfos;
  222.  
  223.   WinEH::FrameInfo *CurrentWinFrameInfo;
  224.   size_t CurrentProcWinFrameInfoStartIndex;
  225.  
  226.   /// Tracks an index to represent the order a symbol was emitted in.
  227.   /// Zero means we did not emit that symbol.
  228.   DenseMap<const MCSymbol *, unsigned> SymbolOrdering;
  229.  
  230.   /// This is stack of current and previous section values saved by
  231.   /// pushSection.
  232.   SmallVector<std::pair<MCSectionSubPair, MCSectionSubPair>, 4> SectionStack;
  233.  
  234.   /// Pointer to the parser's SMLoc if available. This is used to provide
  235.   /// locations for diagnostics.
  236.   const SMLoc *StartTokLocPtr = nullptr;
  237.  
  238.   /// The next unique ID to use when creating a WinCFI-related section (.pdata
  239.   /// or .xdata). This ID ensures that we have a one-to-one mapping from
  240.   /// code section to unwind info section, which MSVC's incremental linker
  241.   /// requires.
  242.   unsigned NextWinCFIID = 0;
  243.  
  244.   bool UseAssemblerInfoForParsing;
  245.  
  246.   /// Is the assembler allowed to insert padding automatically?  For
  247.   /// correctness reasons, we sometimes need to ensure instructions aren't
  248.   /// separated in unexpected ways.  At the moment, this feature is only
  249.   /// useable from an integrated assembler, but assembly syntax is under
  250.   /// discussion for future inclusion.
  251.   bool AllowAutoPadding = false;
  252.  
  253. protected:
  254.   MCStreamer(MCContext &Ctx);
  255.  
  256.   virtual void emitCFIStartProcImpl(MCDwarfFrameInfo &Frame);
  257.   virtual void emitCFIEndProcImpl(MCDwarfFrameInfo &CurFrame);
  258.  
  259.   WinEH::FrameInfo *getCurrentWinFrameInfo() {
  260.     return CurrentWinFrameInfo;
  261.   }
  262.  
  263.   virtual void emitWindowsUnwindTables(WinEH::FrameInfo *Frame);
  264.  
  265.   virtual void emitWindowsUnwindTables();
  266.  
  267.   virtual void emitRawTextImpl(StringRef String);
  268.  
  269.   /// Returns true if the the .cv_loc directive is in the right section.
  270.   bool checkCVLocSection(unsigned FuncId, unsigned FileNo, SMLoc Loc);
  271.  
  272. public:
  273.   MCStreamer(const MCStreamer &) = delete;
  274.   MCStreamer &operator=(const MCStreamer &) = delete;
  275.   virtual ~MCStreamer();
  276.  
  277.   void visitUsedExpr(const MCExpr &Expr);
  278.   virtual void visitUsedSymbol(const MCSymbol &Sym);
  279.  
  280.   void setTargetStreamer(MCTargetStreamer *TS) {
  281.     TargetStreamer.reset(TS);
  282.   }
  283.  
  284.   void setStartTokLocPtr(const SMLoc *Loc) { StartTokLocPtr = Loc; }
  285.   SMLoc getStartTokLoc() const {
  286.     return StartTokLocPtr ? *StartTokLocPtr : SMLoc();
  287.   }
  288.  
  289.   /// State management
  290.   ///
  291.   virtual void reset();
  292.  
  293.   MCContext &getContext() const { return Context; }
  294.  
  295.   virtual MCAssembler *getAssemblerPtr() { return nullptr; }
  296.  
  297.   void setUseAssemblerInfoForParsing(bool v) { UseAssemblerInfoForParsing = v; }
  298.   bool getUseAssemblerInfoForParsing() { return UseAssemblerInfoForParsing; }
  299.  
  300.   MCTargetStreamer *getTargetStreamer() {
  301.     return TargetStreamer.get();
  302.   }
  303.  
  304.   void setAllowAutoPadding(bool v) { AllowAutoPadding = v; }
  305.   bool getAllowAutoPadding() const { return AllowAutoPadding; }
  306.  
  307.   /// When emitting an object file, create and emit a real label. When emitting
  308.   /// textual assembly, this should do nothing to avoid polluting our output.
  309.   virtual MCSymbol *emitCFILabel();
  310.  
  311.   /// Retrieve the current frame info if one is available and it is not yet
  312.   /// closed. Otherwise, issue an error and return null.
  313.   WinEH::FrameInfo *EnsureValidWinFrameInfo(SMLoc Loc);
  314.  
  315.   unsigned getNumFrameInfos();
  316.   ArrayRef<MCDwarfFrameInfo> getDwarfFrameInfos() const;
  317.  
  318.   bool hasUnfinishedDwarfFrameInfo();
  319.  
  320.   unsigned getNumWinFrameInfos() { return WinFrameInfos.size(); }
  321.   ArrayRef<std::unique_ptr<WinEH::FrameInfo>> getWinFrameInfos() const {
  322.     return WinFrameInfos;
  323.   }
  324.  
  325.   void generateCompactUnwindEncodings(MCAsmBackend *MAB);
  326.  
  327.   /// \name Assembly File Formatting.
  328.   /// @{
  329.  
  330.   /// Return true if this streamer supports verbose assembly and if it is
  331.   /// enabled.
  332.   virtual bool isVerboseAsm() const { return false; }
  333.  
  334.   /// Return true if this asm streamer supports emitting unformatted text
  335.   /// to the .s file with EmitRawText.
  336.   virtual bool hasRawTextSupport() const { return false; }
  337.  
  338.   /// Is the integrated assembler required for this streamer to function
  339.   /// correctly?
  340.   virtual bool isIntegratedAssemblerRequired() const { return false; }
  341.  
  342.   /// Add a textual comment.
  343.   ///
  344.   /// Typically for comments that can be emitted to the generated .s
  345.   /// file if applicable as a QoI issue to make the output of the compiler
  346.   /// more readable.  This only affects the MCAsmStreamer, and only when
  347.   /// verbose assembly output is enabled.
  348.   ///
  349.   /// If the comment includes embedded \n's, they will each get the comment
  350.   /// prefix as appropriate.  The added comment should not end with a \n.
  351.   /// By default, each comment is terminated with an end of line, i.e. the
  352.   /// EOL param is set to true by default. If one prefers not to end the
  353.   /// comment with a new line then the EOL param should be passed
  354.   /// with a false value.
  355.   virtual void AddComment(const Twine &T, bool EOL = true) {}
  356.  
  357.   /// Return a raw_ostream that comments can be written to. Unlike
  358.   /// AddComment, you are required to terminate comments with \n if you use this
  359.   /// method.
  360.   virtual raw_ostream &getCommentOS();
  361.  
  362.   /// Print T and prefix it with the comment string (normally #) and
  363.   /// optionally a tab. This prints the comment immediately, not at the end of
  364.   /// the current line. It is basically a safe version of EmitRawText: since it
  365.   /// only prints comments, the object streamer ignores it instead of asserting.
  366.   virtual void emitRawComment(const Twine &T, bool TabPrefix = true);
  367.  
  368.   /// Add explicit comment T. T is required to be a valid
  369.   /// comment in the output and does not need to be escaped.
  370.   virtual void addExplicitComment(const Twine &T);
  371.  
  372.   /// Emit added explicit comments.
  373.   virtual void emitExplicitComments();
  374.  
  375.   /// Emit a blank line to a .s file to pretty it up.
  376.   virtual void addBlankLine() {}
  377.  
  378.   /// @}
  379.  
  380.   /// \name Symbol & Section Management
  381.   /// @{
  382.  
  383.   /// Return the current section that the streamer is emitting code to.
  384.   MCSectionSubPair getCurrentSection() const {
  385.     if (!SectionStack.empty())
  386.       return SectionStack.back().first;
  387.     return MCSectionSubPair();
  388.   }
  389.   MCSection *getCurrentSectionOnly() const { return getCurrentSection().first; }
  390.  
  391.   /// Return the previous section that the streamer is emitting code to.
  392.   MCSectionSubPair getPreviousSection() const {
  393.     if (!SectionStack.empty())
  394.       return SectionStack.back().second;
  395.     return MCSectionSubPair();
  396.   }
  397.  
  398.   /// Returns an index to represent the order a symbol was emitted in.
  399.   /// (zero if we did not emit that symbol)
  400.   unsigned getSymbolOrder(const MCSymbol *Sym) const {
  401.     return SymbolOrdering.lookup(Sym);
  402.   }
  403.  
  404.   /// Update streamer for a new active section.
  405.   ///
  406.   /// This is called by popSection and switchSection, if the current
  407.   /// section changes.
  408.   virtual void changeSection(MCSection *, const MCExpr *);
  409.  
  410.   /// Save the current and previous section on the section stack.
  411.   void pushSection() {
  412.     SectionStack.push_back(
  413.         std::make_pair(getCurrentSection(), getPreviousSection()));
  414.   }
  415.  
  416.   /// Restore the current and previous section from the section stack.
  417.   /// Calls changeSection as needed.
  418.   ///
  419.   /// Returns false if the stack was empty.
  420.   bool popSection() {
  421.     if (SectionStack.size() <= 1)
  422.       return false;
  423.     auto I = SectionStack.end();
  424.     --I;
  425.     MCSectionSubPair OldSection = I->first;
  426.     --I;
  427.     MCSectionSubPair NewSection = I->first;
  428.  
  429.     if (NewSection.first && OldSection != NewSection)
  430.       changeSection(NewSection.first, NewSection.second);
  431.     SectionStack.pop_back();
  432.     return true;
  433.   }
  434.  
  435.   bool subSection(const MCExpr *Subsection) {
  436.     if (SectionStack.empty())
  437.       return false;
  438.  
  439.     switchSection(SectionStack.back().first.first, Subsection);
  440.     return true;
  441.   }
  442.  
  443.   /// Set the current section where code is being emitted to \p Section.  This
  444.   /// is required to update CurSection.
  445.   ///
  446.   /// This corresponds to assembler directives like .section, .text, etc.
  447.   virtual void switchSection(MCSection *Section,
  448.                              const MCExpr *Subsection = nullptr);
  449.  
  450.   /// Set the current section where code is being emitted to \p Section.
  451.   /// This is required to update CurSection. This version does not call
  452.   /// changeSection.
  453.   void switchSectionNoChange(MCSection *Section,
  454.                              const MCExpr *Subsection = nullptr) {
  455.     assert(Section && "Cannot switch to a null section!");
  456.     MCSectionSubPair curSection = SectionStack.back().first;
  457.     SectionStack.back().second = curSection;
  458.     if (MCSectionSubPair(Section, Subsection) != curSection)
  459.       SectionStack.back().first = MCSectionSubPair(Section, Subsection);
  460.   }
  461.  
  462.   /// Create the default sections and set the initial one.
  463.   virtual void initSections(bool NoExecStack, const MCSubtargetInfo &STI);
  464.  
  465.   MCSymbol *endSection(MCSection *Section);
  466.  
  467.   /// Sets the symbol's section.
  468.   ///
  469.   /// Each emitted symbol will be tracked in the ordering table,
  470.   /// so we can sort on them later.
  471.   void assignFragment(MCSymbol *Symbol, MCFragment *Fragment);
  472.  
  473.   /// Returns the mnemonic for \p MI, if the streamer has access to a
  474.   /// instruction printer and returns an empty string otherwise.
  475.   virtual StringRef getMnemonic(MCInst &MI) { return ""; }
  476.  
  477.   /// Emit a label for \p Symbol into the current section.
  478.   ///
  479.   /// This corresponds to an assembler statement such as:
  480.   ///   foo:
  481.   ///
  482.   /// \param Symbol - The symbol to emit. A given symbol should only be
  483.   /// emitted as a label once, and symbols emitted as a label should never be
  484.   /// used in an assignment.
  485.   // FIXME: These emission are non-const because we mutate the symbol to
  486.   // add the section we're emitting it to later.
  487.   virtual void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc());
  488.  
  489.   virtual void emitEHSymAttributes(const MCSymbol *Symbol, MCSymbol *EHSymbol);
  490.  
  491.   /// Note in the output the specified \p Flag.
  492.   virtual void emitAssemblerFlag(MCAssemblerFlag Flag);
  493.  
  494.   /// Emit the given list \p Options of strings as linker
  495.   /// options into the output.
  496.   virtual void emitLinkerOptions(ArrayRef<std::string> Kind) {}
  497.  
  498.   /// Note in the output the specified region \p Kind.
  499.   virtual void emitDataRegion(MCDataRegionType Kind) {}
  500.  
  501.   /// Specify the Mach-O minimum deployment target version.
  502.   virtual void emitVersionMin(MCVersionMinType Type, unsigned Major,
  503.                               unsigned Minor, unsigned Update,
  504.                               VersionTuple SDKVersion) {}
  505.  
  506.   /// Emit/Specify Mach-O build version command.
  507.   /// \p Platform should be one of MachO::PlatformType.
  508.   virtual void emitBuildVersion(unsigned Platform, unsigned Major,
  509.                                 unsigned Minor, unsigned Update,
  510.                                 VersionTuple SDKVersion) {}
  511.  
  512.   virtual void emitDarwinTargetVariantBuildVersion(unsigned Platform,
  513.                                                    unsigned Major,
  514.                                                    unsigned Minor,
  515.                                                    unsigned Update,
  516.                                                    VersionTuple SDKVersion) {}
  517.  
  518.   void emitVersionForTarget(const Triple &Target,
  519.                             const VersionTuple &SDKVersion,
  520.                             const Triple *DarwinTargetVariantTriple,
  521.                             const VersionTuple &DarwinTargetVariantSDKVersion);
  522.  
  523.   /// Note in the output that the specified \p Func is a Thumb mode
  524.   /// function (ARM target only).
  525.   virtual void emitThumbFunc(MCSymbol *Func);
  526.  
  527.   /// Emit an assignment of \p Value to \p Symbol.
  528.   ///
  529.   /// This corresponds to an assembler statement such as:
  530.   ///  symbol = value
  531.   ///
  532.   /// The assignment generates no code, but has the side effect of binding the
  533.   /// value in the current context. For the assembly streamer, this prints the
  534.   /// binding into the .s file.
  535.   ///
  536.   /// \param Symbol - The symbol being assigned to.
  537.   /// \param Value - The value for the symbol.
  538.   virtual void emitAssignment(MCSymbol *Symbol, const MCExpr *Value);
  539.  
  540.   /// Emit an assignment of \p Value to \p Symbol, but only if \p Value is also
  541.   /// emitted.
  542.   virtual void emitConditionalAssignment(MCSymbol *Symbol, const MCExpr *Value);
  543.  
  544.   /// Emit an weak reference from \p Alias to \p Symbol.
  545.   ///
  546.   /// This corresponds to an assembler statement such as:
  547.   ///  .weakref alias, symbol
  548.   ///
  549.   /// \param Alias - The alias that is being created.
  550.   /// \param Symbol - The symbol being aliased.
  551.   virtual void emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
  552.  
  553.   /// Add the given \p Attribute to \p Symbol.
  554.   virtual bool emitSymbolAttribute(MCSymbol *Symbol,
  555.                                    MCSymbolAttr Attribute) = 0;
  556.  
  557.   /// Set the \p DescValue for the \p Symbol.
  558.   ///
  559.   /// \param Symbol - The symbol to have its n_desc field set.
  560.   /// \param DescValue - The value to set into the n_desc field.
  561.   virtual void emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
  562.  
  563.   /// Start emitting COFF symbol definition
  564.   ///
  565.   /// \param Symbol - The symbol to have its External & Type fields set.
  566.   virtual void beginCOFFSymbolDef(const MCSymbol *Symbol);
  567.  
  568.   /// Emit the storage class of the symbol.
  569.   ///
  570.   /// \param StorageClass - The storage class the symbol should have.
  571.   virtual void emitCOFFSymbolStorageClass(int StorageClass);
  572.  
  573.   /// Emit the type of the symbol.
  574.   ///
  575.   /// \param Type - A COFF type identifier (see COFF::SymbolType in X86COFF.h)
  576.   virtual void emitCOFFSymbolType(int Type);
  577.  
  578.   /// Marks the end of the symbol definition.
  579.   virtual void endCOFFSymbolDef();
  580.  
  581.   virtual void emitCOFFSafeSEH(MCSymbol const *Symbol);
  582.  
  583.   /// Emits the symbol table index of a Symbol into the current section.
  584.   virtual void emitCOFFSymbolIndex(MCSymbol const *Symbol);
  585.  
  586.   /// Emits a COFF section index.
  587.   ///
  588.   /// \param Symbol - Symbol the section number relocation should point to.
  589.   virtual void emitCOFFSectionIndex(MCSymbol const *Symbol);
  590.  
  591.   /// Emits a COFF section relative relocation.
  592.   ///
  593.   /// \param Symbol - Symbol the section relative relocation should point to.
  594.   virtual void emitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset);
  595.  
  596.   /// Emits a COFF image relative relocation.
  597.   ///
  598.   /// \param Symbol - Symbol the image relative relocation should point to.
  599.   virtual void emitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset);
  600.  
  601.   /// Emits an lcomm directive with XCOFF csect information.
  602.   ///
  603.   /// \param LabelSym - Label on the block of storage.
  604.   /// \param Size - The size of the block of storage.
  605.   /// \param CsectSym - Csect name for the block of storage.
  606.   /// \param Alignment - The alignment of the symbol in bytes.
  607.   virtual void emitXCOFFLocalCommonSymbol(MCSymbol *LabelSym, uint64_t Size,
  608.                                           MCSymbol *CsectSym, Align Alignment);
  609.  
  610.   /// Emit a symbol's linkage and visibility with a linkage directive for XCOFF.
  611.   ///
  612.   /// \param Symbol - The symbol to emit.
  613.   /// \param Linkage - The linkage of the symbol to emit.
  614.   /// \param Visibility - The visibility of the symbol to emit or MCSA_Invalid
  615.   /// if the symbol does not have an explicit visibility.
  616.   virtual void emitXCOFFSymbolLinkageWithVisibility(MCSymbol *Symbol,
  617.                                                     MCSymbolAttr Linkage,
  618.                                                     MCSymbolAttr Visibility);
  619.  
  620.   /// Emit a XCOFF .rename directive which creates a synonym for an illegal or
  621.   /// undesirable name.
  622.   ///
  623.   /// \param Name - The name used internally in the assembly for references to
  624.   /// the symbol.
  625.   /// \param Rename - The value to which the Name parameter is
  626.   /// changed at the end of assembly.
  627.   virtual void emitXCOFFRenameDirective(const MCSymbol *Name, StringRef Rename);
  628.  
  629.   /// Emit an XCOFF .except directive which adds information about
  630.   /// a trap instruction to the object file exception section
  631.   ///
  632.   /// \param Symbol - The function containing the trap.
  633.   /// \param Lang - The language code for the exception entry.
  634.   /// \param Reason - The reason code for the exception entry.
  635.   virtual void emitXCOFFExceptDirective(const MCSymbol *Symbol,
  636.                                         const MCSymbol *Trap,
  637.                                         unsigned Lang, unsigned Reason,
  638.                                         unsigned FunctionSize, bool hasDebug);
  639.  
  640.   /// Emit a XCOFF .ref directive which creates R_REF type entry in the
  641.   /// relocation table for one or more symbols.
  642.   ///
  643.   /// \param Sym - The symbol on the .ref directive.
  644.   virtual void emitXCOFFRefDirective(StringRef Sym);
  645.  
  646.   /// Emit an ELF .size directive.
  647.   ///
  648.   /// This corresponds to an assembler statement such as:
  649.   ///  .size symbol, expression
  650.   virtual void emitELFSize(MCSymbol *Symbol, const MCExpr *Value);
  651.  
  652.   /// Emit an ELF .symver directive.
  653.   ///
  654.   /// This corresponds to an assembler statement such as:
  655.   ///  .symver _start, foo@@SOME_VERSION
  656.   virtual void emitELFSymverDirective(const MCSymbol *OriginalSym,
  657.                                       StringRef Name, bool KeepOriginalSym);
  658.  
  659.   /// Emit a Linker Optimization Hint (LOH) directive.
  660.   /// \param Args - Arguments of the LOH.
  661.   virtual void emitLOHDirective(MCLOHType Kind, const MCLOHArgs &Args) {}
  662.  
  663.   /// Emit a .gnu_attribute directive.
  664.   virtual void emitGNUAttribute(unsigned Tag, unsigned Value) {}
  665.  
  666.   /// Emit a common symbol.
  667.   ///
  668.   /// \param Symbol - The common symbol to emit.
  669.   /// \param Size - The size of the common symbol.
  670.   /// \param ByteAlignment - The alignment of the symbol.
  671.   virtual void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  672.                                 Align ByteAlignment) = 0;
  673.  
  674.   /// Emit a local common (.lcomm) symbol.
  675.   ///
  676.   /// \param Symbol - The common symbol to emit.
  677.   /// \param Size - The size of the common symbol.
  678.   /// \param ByteAlignment - The alignment of the common symbol in bytes.
  679.   virtual void emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
  680.                                      Align ByteAlignment);
  681.  
  682.   /// Emit the zerofill section and an optional symbol.
  683.   ///
  684.   /// \param Section - The zerofill section to create and or to put the symbol
  685.   /// \param Symbol - The zerofill symbol to emit, if non-NULL.
  686.   /// \param Size - The size of the zerofill symbol.
  687.   /// \param ByteAlignment - The alignment of the zerofill symbol.
  688.   virtual void emitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
  689.                             uint64_t Size = 0, Align ByteAlignment = Align(1),
  690.                             SMLoc Loc = SMLoc()) = 0;
  691.  
  692.   /// Emit a thread local bss (.tbss) symbol.
  693.   ///
  694.   /// \param Section - The thread local common section.
  695.   /// \param Symbol - The thread local common symbol to emit.
  696.   /// \param Size - The size of the symbol.
  697.   /// \param ByteAlignment - The alignment of the thread local common symbol.
  698.   virtual void emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
  699.                               uint64_t Size, Align ByteAlignment = Align(1));
  700.  
  701.   /// @}
  702.   /// \name Generating Data
  703.   /// @{
  704.  
  705.   /// Emit the bytes in \p Data into the output.
  706.   ///
  707.   /// This is used to implement assembler directives such as .byte, .ascii,
  708.   /// etc.
  709.   virtual void emitBytes(StringRef Data);
  710.  
  711.   /// Functionally identical to EmitBytes. When emitting textual assembly, this
  712.   /// method uses .byte directives instead of .ascii or .asciz for readability.
  713.   virtual void emitBinaryData(StringRef Data);
  714.  
  715.   /// Emit the expression \p Value into the output as a native
  716.   /// integer of the given \p Size bytes.
  717.   ///
  718.   /// This is used to implement assembler directives such as .word, .quad,
  719.   /// etc.
  720.   ///
  721.   /// \param Value - The value to emit.
  722.   /// \param Size - The size of the integer (in bytes) to emit. This must
  723.   /// match a native machine width.
  724.   /// \param Loc - The location of the expression for error reporting.
  725.   virtual void emitValueImpl(const MCExpr *Value, unsigned Size,
  726.                              SMLoc Loc = SMLoc());
  727.  
  728.   void emitValue(const MCExpr *Value, unsigned Size, SMLoc Loc = SMLoc());
  729.  
  730.   /// Special case of EmitValue that avoids the client having
  731.   /// to pass in a MCExpr for constant integers.
  732.   virtual void emitIntValue(uint64_t Value, unsigned Size);
  733.   virtual void emitIntValue(APInt Value);
  734.  
  735.   /// Special case of EmitValue that avoids the client having to pass
  736.   /// in a MCExpr for constant integers & prints in Hex format for certain
  737.   /// modes.
  738.   virtual void emitIntValueInHex(uint64_t Value, unsigned Size) {
  739.     emitIntValue(Value, Size);
  740.   }
  741.  
  742.   void emitInt8(uint64_t Value) { emitIntValue(Value, 1); }
  743.   void emitInt16(uint64_t Value) { emitIntValue(Value, 2); }
  744.   void emitInt32(uint64_t Value) { emitIntValue(Value, 4); }
  745.   void emitInt64(uint64_t Value) { emitIntValue(Value, 8); }
  746.  
  747.   /// Special case of EmitValue that avoids the client having to pass
  748.   /// in a MCExpr for constant integers & prints in Hex format for certain
  749.   /// modes, pads the field with leading zeros to Size width
  750.   virtual void emitIntValueInHexWithPadding(uint64_t Value, unsigned Size) {
  751.     emitIntValue(Value, Size);
  752.   }
  753.  
  754.   virtual void emitULEB128Value(const MCExpr *Value);
  755.  
  756.   virtual void emitSLEB128Value(const MCExpr *Value);
  757.  
  758.   /// Special case of EmitULEB128Value that avoids the client having to
  759.   /// pass in a MCExpr for constant integers.
  760.   unsigned emitULEB128IntValue(uint64_t Value, unsigned PadTo = 0);
  761.  
  762.   /// Special case of EmitSLEB128Value that avoids the client having to
  763.   /// pass in a MCExpr for constant integers.
  764.   unsigned emitSLEB128IntValue(int64_t Value);
  765.  
  766.   /// Special case of EmitValue that avoids the client having to pass in
  767.   /// a MCExpr for MCSymbols.
  768.   void emitSymbolValue(const MCSymbol *Sym, unsigned Size,
  769.                        bool IsSectionRelative = false);
  770.  
  771.   /// Emit the expression \p Value into the output as a dtprel
  772.   /// (64-bit DTP relative) value.
  773.   ///
  774.   /// This is used to implement assembler directives such as .dtpreldword on
  775.   /// targets that support them.
  776.   virtual void emitDTPRel64Value(const MCExpr *Value);
  777.  
  778.   /// Emit the expression \p Value into the output as a dtprel
  779.   /// (32-bit DTP relative) value.
  780.   ///
  781.   /// This is used to implement assembler directives such as .dtprelword on
  782.   /// targets that support them.
  783.   virtual void emitDTPRel32Value(const MCExpr *Value);
  784.  
  785.   /// Emit the expression \p Value into the output as a tprel
  786.   /// (64-bit TP relative) value.
  787.   ///
  788.   /// This is used to implement assembler directives such as .tpreldword on
  789.   /// targets that support them.
  790.   virtual void emitTPRel64Value(const MCExpr *Value);
  791.  
  792.   /// Emit the expression \p Value into the output as a tprel
  793.   /// (32-bit TP relative) value.
  794.   ///
  795.   /// This is used to implement assembler directives such as .tprelword on
  796.   /// targets that support them.
  797.   virtual void emitTPRel32Value(const MCExpr *Value);
  798.  
  799.   /// Emit the expression \p Value into the output as a gprel64 (64-bit
  800.   /// GP relative) value.
  801.   ///
  802.   /// This is used to implement assembler directives such as .gpdword on
  803.   /// targets that support them.
  804.   virtual void emitGPRel64Value(const MCExpr *Value);
  805.  
  806.   /// Emit the expression \p Value into the output as a gprel32 (32-bit
  807.   /// GP relative) value.
  808.   ///
  809.   /// This is used to implement assembler directives such as .gprel32 on
  810.   /// targets that support them.
  811.   virtual void emitGPRel32Value(const MCExpr *Value);
  812.  
  813.   /// Emit NumBytes bytes worth of the value specified by FillValue.
  814.   /// This implements directives such as '.space'.
  815.   void emitFill(uint64_t NumBytes, uint8_t FillValue);
  816.  
  817.   /// Emit \p Size bytes worth of the value specified by \p FillValue.
  818.   ///
  819.   /// This is used to implement assembler directives such as .space or .skip.
  820.   ///
  821.   /// \param NumBytes - The number of bytes to emit.
  822.   /// \param FillValue - The value to use when filling bytes.
  823.   /// \param Loc - The location of the expression for error reporting.
  824.   virtual void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
  825.                         SMLoc Loc = SMLoc());
  826.  
  827.   /// Emit \p NumValues copies of \p Size bytes. Each \p Size bytes is
  828.   /// taken from the lowest order 4 bytes of \p Expr expression.
  829.   ///
  830.   /// This is used to implement assembler directives such as .fill.
  831.   ///
  832.   /// \param NumValues - The number of copies of \p Size bytes to emit.
  833.   /// \param Size - The size (in bytes) of each repeated value.
  834.   /// \param Expr - The expression from which \p Size bytes are used.
  835.   virtual void emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
  836.                         SMLoc Loc = SMLoc());
  837.  
  838.   virtual void emitNops(int64_t NumBytes, int64_t ControlledNopLength,
  839.                         SMLoc Loc, const MCSubtargetInfo& STI);
  840.  
  841.   /// Emit NumBytes worth of zeros.
  842.   /// This function properly handles data in virtual sections.
  843.   void emitZeros(uint64_t NumBytes);
  844.  
  845.   /// Emit some number of copies of \p Value until the byte alignment \p
  846.   /// ByteAlignment is reached.
  847.   ///
  848.   /// If the number of bytes need to emit for the alignment is not a multiple
  849.   /// of \p ValueSize, then the contents of the emitted fill bytes is
  850.   /// undefined.
  851.   ///
  852.   /// This used to implement the .align assembler directive.
  853.   ///
  854.   /// \param Alignment - The alignment to reach.
  855.   /// \param Value - The value to use when filling bytes.
  856.   /// \param ValueSize - The size of the integer (in bytes) to emit for
  857.   /// \p Value. This must match a native machine width.
  858.   /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
  859.   /// the alignment cannot be reached in this many bytes, no bytes are
  860.   /// emitted.
  861.   virtual void emitValueToAlignment(Align Alignment, int64_t Value = 0,
  862.                                     unsigned ValueSize = 1,
  863.                                     unsigned MaxBytesToEmit = 0);
  864.  
  865.   /// Emit nops until the byte alignment \p ByteAlignment is reached.
  866.   ///
  867.   /// This used to align code where the alignment bytes may be executed.  This
  868.   /// can emit different bytes for different sizes to optimize execution.
  869.   ///
  870.   /// \param Alignment - The alignment to reach.
  871.   /// \param STI - The MCSubtargetInfo in operation when padding is emitted.
  872.   /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
  873.   /// the alignment cannot be reached in this many bytes, no bytes are
  874.   /// emitted.
  875.   virtual void emitCodeAlignment(Align Alignment, const MCSubtargetInfo *STI,
  876.                                  unsigned MaxBytesToEmit = 0);
  877.  
  878.   /// Emit some number of copies of \p Value until the byte offset \p
  879.   /// Offset is reached.
  880.   ///
  881.   /// This is used to implement assembler directives such as .org.
  882.   ///
  883.   /// \param Offset - The offset to reach. This may be an expression, but the
  884.   /// expression must be associated with the current section.
  885.   /// \param Value - The value to use when filling bytes.
  886.   virtual void emitValueToOffset(const MCExpr *Offset, unsigned char Value,
  887.                                  SMLoc Loc);
  888.  
  889.   /// @}
  890.  
  891.   /// Switch to a new logical file.  This is used to implement the '.file
  892.   /// "foo.c"' assembler directive.
  893.   virtual void emitFileDirective(StringRef Filename);
  894.  
  895.   /// Emit ".file assembler diretive with additioal info.
  896.   virtual void emitFileDirective(StringRef Filename, StringRef CompilerVerion,
  897.                                  StringRef TimeStamp, StringRef Description);
  898.  
  899.   /// Emit the "identifiers" directive.  This implements the
  900.   /// '.ident "version foo"' assembler directive.
  901.   virtual void emitIdent(StringRef IdentString) {}
  902.  
  903.   /// Associate a filename with a specified logical file number.  This
  904.   /// implements the DWARF2 '.file 4 "foo.c"' assembler directive.
  905.   unsigned emitDwarfFileDirective(
  906.       unsigned FileNo, StringRef Directory, StringRef Filename,
  907.       std::optional<MD5::MD5Result> Checksum = std::nullopt,
  908.       std::optional<StringRef> Source = std::nullopt, unsigned CUID = 0) {
  909.     return cantFail(
  910.         tryEmitDwarfFileDirective(FileNo, Directory, Filename, Checksum,
  911.                                   Source, CUID));
  912.   }
  913.  
  914.   /// Associate a filename with a specified logical file number.
  915.   /// Also associate a directory, optional checksum, and optional source
  916.   /// text with the logical file.  This implements the DWARF2
  917.   /// '.file 4 "dir/foo.c"' assembler directive, and the DWARF5
  918.   /// '.file 4 "dir/foo.c" md5 "..." source "..."' assembler directive.
  919.   virtual Expected<unsigned> tryEmitDwarfFileDirective(
  920.       unsigned FileNo, StringRef Directory, StringRef Filename,
  921.       std::optional<MD5::MD5Result> Checksum = std::nullopt,
  922.       std::optional<StringRef> Source = std::nullopt, unsigned CUID = 0);
  923.  
  924.   /// Specify the "root" file of the compilation, using the ".file 0" extension.
  925.   virtual void emitDwarfFile0Directive(StringRef Directory, StringRef Filename,
  926.                                        std::optional<MD5::MD5Result> Checksum,
  927.                                        std::optional<StringRef> Source,
  928.                                        unsigned CUID = 0);
  929.  
  930.   virtual void emitCFIBKeyFrame();
  931.   virtual void emitCFIMTETaggedFrame();
  932.  
  933.   /// This implements the DWARF2 '.loc fileno lineno ...' assembler
  934.   /// directive.
  935.   virtual void emitDwarfLocDirective(unsigned FileNo, unsigned Line,
  936.                                      unsigned Column, unsigned Flags,
  937.                                      unsigned Isa, unsigned Discriminator,
  938.                                      StringRef FileName);
  939.  
  940.   /// Associate a filename with a specified logical file number, and also
  941.   /// specify that file's checksum information.  This implements the '.cv_file 4
  942.   /// "foo.c"' assembler directive. Returns true on success.
  943.   virtual bool emitCVFileDirective(unsigned FileNo, StringRef Filename,
  944.                                    ArrayRef<uint8_t> Checksum,
  945.                                    unsigned ChecksumKind);
  946.  
  947.   /// Introduces a function id for use with .cv_loc.
  948.   virtual bool emitCVFuncIdDirective(unsigned FunctionId);
  949.  
  950.   /// Introduces an inline call site id for use with .cv_loc. Includes
  951.   /// extra information for inline line table generation.
  952.   virtual bool emitCVInlineSiteIdDirective(unsigned FunctionId, unsigned IAFunc,
  953.                                            unsigned IAFile, unsigned IALine,
  954.                                            unsigned IACol, SMLoc Loc);
  955.  
  956.   /// This implements the CodeView '.cv_loc' assembler directive.
  957.   virtual void emitCVLocDirective(unsigned FunctionId, unsigned FileNo,
  958.                                   unsigned Line, unsigned Column,
  959.                                   bool PrologueEnd, bool IsStmt,
  960.                                   StringRef FileName, SMLoc Loc);
  961.  
  962.   /// This implements the CodeView '.cv_linetable' assembler directive.
  963.   virtual void emitCVLinetableDirective(unsigned FunctionId,
  964.                                         const MCSymbol *FnStart,
  965.                                         const MCSymbol *FnEnd);
  966.  
  967.   /// This implements the CodeView '.cv_inline_linetable' assembler
  968.   /// directive.
  969.   virtual void emitCVInlineLinetableDirective(unsigned PrimaryFunctionId,
  970.                                               unsigned SourceFileId,
  971.                                               unsigned SourceLineNum,
  972.                                               const MCSymbol *FnStartSym,
  973.                                               const MCSymbol *FnEndSym);
  974.  
  975.   /// This implements the CodeView '.cv_def_range' assembler
  976.   /// directive.
  977.   virtual void emitCVDefRangeDirective(
  978.       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
  979.       StringRef FixedSizePortion);
  980.  
  981.   virtual void emitCVDefRangeDirective(
  982.       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
  983.       codeview::DefRangeRegisterRelHeader DRHdr);
  984.  
  985.   virtual void emitCVDefRangeDirective(
  986.       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
  987.       codeview::DefRangeSubfieldRegisterHeader DRHdr);
  988.  
  989.   virtual void emitCVDefRangeDirective(
  990.       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
  991.       codeview::DefRangeRegisterHeader DRHdr);
  992.  
  993.   virtual void emitCVDefRangeDirective(
  994.       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
  995.       codeview::DefRangeFramePointerRelHeader DRHdr);
  996.  
  997.   /// This implements the CodeView '.cv_stringtable' assembler directive.
  998.   virtual void emitCVStringTableDirective() {}
  999.  
  1000.   /// This implements the CodeView '.cv_filechecksums' assembler directive.
  1001.   virtual void emitCVFileChecksumsDirective() {}
  1002.  
  1003.   /// This implements the CodeView '.cv_filechecksumoffset' assembler
  1004.   /// directive.
  1005.   virtual void emitCVFileChecksumOffsetDirective(unsigned FileNo) {}
  1006.  
  1007.   /// This implements the CodeView '.cv_fpo_data' assembler directive.
  1008.   virtual void emitCVFPOData(const MCSymbol *ProcSym, SMLoc Loc = {}) {}
  1009.  
  1010.   /// Emit the absolute difference between two symbols.
  1011.   ///
  1012.   /// \pre Offset of \c Hi is greater than the offset \c Lo.
  1013.   virtual void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
  1014.                                       unsigned Size);
  1015.  
  1016.   /// Emit the absolute difference between two symbols encoded with ULEB128.
  1017.   virtual void emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi,
  1018.                                                const MCSymbol *Lo);
  1019.  
  1020.   virtual MCSymbol *getDwarfLineTableSymbol(unsigned CUID);
  1021.   virtual void emitCFISections(bool EH, bool Debug);
  1022.   void emitCFIStartProc(bool IsSimple, SMLoc Loc = SMLoc());
  1023.   void emitCFIEndProc();
  1024.   virtual void emitCFIDefCfa(int64_t Register, int64_t Offset);
  1025.   virtual void emitCFIDefCfaOffset(int64_t Offset);
  1026.   virtual void emitCFIDefCfaRegister(int64_t Register);
  1027.   virtual void emitCFILLVMDefAspaceCfa(int64_t Register, int64_t Offset,
  1028.                                        int64_t AddressSpace);
  1029.   virtual void emitCFIOffset(int64_t Register, int64_t Offset);
  1030.   virtual void emitCFIPersonality(const MCSymbol *Sym, unsigned Encoding);
  1031.   virtual void emitCFILsda(const MCSymbol *Sym, unsigned Encoding);
  1032.   virtual void emitCFIRememberState();
  1033.   virtual void emitCFIRestoreState();
  1034.   virtual void emitCFISameValue(int64_t Register);
  1035.   virtual void emitCFIRestore(int64_t Register);
  1036.   virtual void emitCFIRelOffset(int64_t Register, int64_t Offset);
  1037.   virtual void emitCFIAdjustCfaOffset(int64_t Adjustment);
  1038.   virtual void emitCFIEscape(StringRef Values);
  1039.   virtual void emitCFIReturnColumn(int64_t Register);
  1040.   virtual void emitCFIGnuArgsSize(int64_t Size);
  1041.   virtual void emitCFISignalFrame();
  1042.   virtual void emitCFIUndefined(int64_t Register);
  1043.   virtual void emitCFIRegister(int64_t Register1, int64_t Register2);
  1044.   virtual void emitCFIWindowSave();
  1045.   virtual void emitCFINegateRAState();
  1046.  
  1047.   virtual void emitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc = SMLoc());
  1048.   virtual void emitWinCFIEndProc(SMLoc Loc = SMLoc());
  1049.   /// This is used on platforms, such as Windows on ARM64, that require function
  1050.   /// or funclet sizes to be emitted in .xdata before the End marker is emitted
  1051.   /// for the frame.  We cannot use the End marker, as it is not set at the
  1052.   /// point of emitting .xdata, in order to indicate that the frame is active.
  1053.   virtual void emitWinCFIFuncletOrFuncEnd(SMLoc Loc = SMLoc());
  1054.   virtual void emitWinCFIStartChained(SMLoc Loc = SMLoc());
  1055.   virtual void emitWinCFIEndChained(SMLoc Loc = SMLoc());
  1056.   virtual void emitWinCFIPushReg(MCRegister Register, SMLoc Loc = SMLoc());
  1057.   virtual void emitWinCFISetFrame(MCRegister Register, unsigned Offset,
  1058.                                   SMLoc Loc = SMLoc());
  1059.   virtual void emitWinCFIAllocStack(unsigned Size, SMLoc Loc = SMLoc());
  1060.   virtual void emitWinCFISaveReg(MCRegister Register, unsigned Offset,
  1061.                                  SMLoc Loc = SMLoc());
  1062.   virtual void emitWinCFISaveXMM(MCRegister Register, unsigned Offset,
  1063.                                  SMLoc Loc = SMLoc());
  1064.   virtual void emitWinCFIPushFrame(bool Code, SMLoc Loc = SMLoc());
  1065.   virtual void emitWinCFIEndProlog(SMLoc Loc = SMLoc());
  1066.   virtual void emitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except,
  1067.                                 SMLoc Loc = SMLoc());
  1068.   virtual void emitWinEHHandlerData(SMLoc Loc = SMLoc());
  1069.  
  1070.   virtual void emitCGProfileEntry(const MCSymbolRefExpr *From,
  1071.                                   const MCSymbolRefExpr *To, uint64_t Count);
  1072.  
  1073.   /// Get the .pdata section used for the given section. Typically the given
  1074.   /// section is either the main .text section or some other COMDAT .text
  1075.   /// section, but it may be any section containing code.
  1076.   MCSection *getAssociatedPDataSection(const MCSection *TextSec);
  1077.  
  1078.   /// Get the .xdata section used for the given section.
  1079.   MCSection *getAssociatedXDataSection(const MCSection *TextSec);
  1080.  
  1081.   virtual void emitSyntaxDirective();
  1082.  
  1083.   /// Record a relocation described by the .reloc directive. Return std::nullopt
  1084.   /// if succeeded. Otherwise, return a pair (Name is invalid, error message).
  1085.   virtual std::optional<std::pair<bool, std::string>>
  1086.   emitRelocDirective(const MCExpr &Offset, StringRef Name, const MCExpr *Expr,
  1087.                      SMLoc Loc, const MCSubtargetInfo &STI) {
  1088.     return std::nullopt;
  1089.   }
  1090.  
  1091.   virtual void emitAddrsig() {}
  1092.   virtual void emitAddrsigSym(const MCSymbol *Sym) {}
  1093.  
  1094.   /// Emit the given \p Instruction into the current section.
  1095.   virtual void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI);
  1096.  
  1097.   /// Emit the a pseudo probe into the current section.
  1098.   virtual void emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
  1099.                                uint64_t Attr,
  1100.                                const MCPseudoProbeInlineStack &InlineStack,
  1101.                                MCSymbol *FnSym);
  1102.  
  1103.   /// Set the bundle alignment mode from now on in the section.
  1104.   /// The value 1 means turn the bundle alignment off.
  1105.   virtual void emitBundleAlignMode(Align Alignment);
  1106.  
  1107.   /// The following instructions are a bundle-locked group.
  1108.   ///
  1109.   /// \param AlignToEnd - If true, the bundle-locked group will be aligned to
  1110.   ///                     the end of a bundle.
  1111.   virtual void emitBundleLock(bool AlignToEnd);
  1112.  
  1113.   /// Ends a bundle-locked group.
  1114.   virtual void emitBundleUnlock();
  1115.  
  1116.   /// If this file is backed by a assembly streamer, this dumps the
  1117.   /// specified string in the output .s file.  This capability is indicated by
  1118.   /// the hasRawTextSupport() predicate.  By default this aborts.
  1119.   void emitRawText(const Twine &String);
  1120.  
  1121.   /// Streamer specific finalization.
  1122.   virtual void finishImpl();
  1123.   /// Finish emission of machine code.
  1124.   void finish(SMLoc EndLoc = SMLoc());
  1125.  
  1126.   virtual bool mayHaveInstructions(MCSection &Sec) const { return true; }
  1127.  
  1128.   /// Emit a special value of 0xffffffff if producing 64-bit debugging info.
  1129.   void maybeEmitDwarf64Mark();
  1130.  
  1131.   /// Emit a unit length field. The actual format, DWARF32 or DWARF64, is chosen
  1132.   /// according to the settings.
  1133.   virtual void emitDwarfUnitLength(uint64_t Length, const Twine &Comment);
  1134.  
  1135.   /// Emit a unit length field. The actual format, DWARF32 or DWARF64, is chosen
  1136.   /// according to the settings.
  1137.   /// Return the end symbol generated inside, the caller needs to emit it.
  1138.   virtual MCSymbol *emitDwarfUnitLength(const Twine &Prefix,
  1139.                                         const Twine &Comment);
  1140.  
  1141.   /// Emit the debug line start label.
  1142.   virtual void emitDwarfLineStartLabel(MCSymbol *StartSym);
  1143.  
  1144.   /// Emit the debug line end entry.
  1145.   virtual void emitDwarfLineEndEntry(MCSection *Section, MCSymbol *LastLabel) {}
  1146.  
  1147.   /// If targets does not support representing debug line section by .loc/.file
  1148.   /// directives in assembly output, we need to populate debug line section with
  1149.   /// raw debug line contents.
  1150.   virtual void emitDwarfAdvanceLineAddr(int64_t LineDelta,
  1151.                                         const MCSymbol *LastLabel,
  1152.                                         const MCSymbol *Label,
  1153.                                         unsigned PointerSize) {}
  1154.  
  1155.   /// Do finalization for the streamer at the end of a section.
  1156.   virtual void doFinalizationAtSectionEnd(MCSection *Section) {}
  1157. };
  1158.  
  1159. /// Create a dummy machine code streamer, which does nothing. This is useful for
  1160. /// timing the assembler front end.
  1161. MCStreamer *createNullStreamer(MCContext &Ctx);
  1162.  
  1163. } // end namespace llvm
  1164.  
  1165. #endif // LLVM_MC_MCSTREAMER_H
  1166.