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1 //===- MCStreamer.h - High-level Streaming Machine Code Output --*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file declares the MCStreamer class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_MC_MCSTREAMER_H
15 #define LLVM_MC_MCSTREAMER_H
16 
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/MC/MCDirectives.h"
20 #include "llvm/MC/MCDwarf.h"
21 #include "llvm/MC/MCLinkerOptimizationHint.h"
22 #include "llvm/MC/MCSymbol.h"
23 #include "llvm/MC/MCWinEH.h"
24 #include "llvm/Support/DataTypes.h"
25 #include "llvm/Support/SMLoc.h"
26 #include <string>
27 
28 namespace llvm {
29 class MCAsmBackend;
30 class MCCodeEmitter;
31 class MCContext;
32 class MCExpr;
33 class MCInst;
34 class MCInstPrinter;
35 class MCSection;
36 class MCStreamer;
37 class MCSymbolELF;
38 class MCSymbolRefExpr;
39 class MCSubtargetInfo;
40 class StringRef;
41 class Twine;
42 class raw_ostream;
43 class formatted_raw_ostream;
44 class AssemblerConstantPools;
45 
46 typedef std::pair<MCSection *, const MCExpr *> MCSectionSubPair;
47 
48 /// Target specific streamer interface. This is used so that targets can
49 /// implement support for target specific assembly directives.
50 ///
51 /// If target foo wants to use this, it should implement 3 classes:
52 /// * FooTargetStreamer : public MCTargetStreamer
53 /// * FooTargetAsmStreamer : public FooTargetStreamer
54 /// * FooTargetELFStreamer : public FooTargetStreamer
55 ///
56 /// FooTargetStreamer should have a pure virtual method for each directive. For
57 /// example, for a ".bar symbol_name" directive, it should have
58 /// virtual emitBar(const MCSymbol &Symbol) = 0;
59 ///
60 /// The FooTargetAsmStreamer and FooTargetELFStreamer classes implement the
61 /// method. The assembly streamer just prints ".bar symbol_name". The object
62 /// streamer does whatever is needed to implement .bar in the object file.
63 ///
64 /// In the assembly printer and parser the target streamer can be used by
65 /// calling getTargetStreamer and casting it to FooTargetStreamer:
66 ///
67 /// MCTargetStreamer &TS = OutStreamer.getTargetStreamer();
68 /// FooTargetStreamer &ATS = static_cast<FooTargetStreamer &>(TS);
69 ///
70 /// The base classes FooTargetAsmStreamer and FooTargetELFStreamer should
71 /// *never* be treated differently. Callers should always talk to a
72 /// FooTargetStreamer.
73 class MCTargetStreamer {
74 protected:
75   MCStreamer &Streamer;
76 
77 public:
78   MCTargetStreamer(MCStreamer &S);
79   virtual ~MCTargetStreamer();
80 
getStreamer()81   MCStreamer &getStreamer() { return Streamer; }
82 
83   // Allow a target to add behavior to the EmitLabel of MCStreamer.
84   virtual void emitLabel(MCSymbol *Symbol);
85   // Allow a target to add behavior to the emitAssignment of MCStreamer.
86   virtual void emitAssignment(MCSymbol *Symbol, const MCExpr *Value);
87 
88   virtual void prettyPrintAsm(MCInstPrinter &InstPrinter, raw_ostream &OS,
89                               const MCInst &Inst, const MCSubtargetInfo &STI);
90 
91   virtual void finish();
92 };
93 
94 // FIXME: declared here because it is used from
95 // lib/CodeGen/AsmPrinter/ARMException.cpp.
96 class ARMTargetStreamer : public MCTargetStreamer {
97 public:
98   ARMTargetStreamer(MCStreamer &S);
99   ~ARMTargetStreamer() override;
100 
101   virtual void emitFnStart();
102   virtual void emitFnEnd();
103   virtual void emitCantUnwind();
104   virtual void emitPersonality(const MCSymbol *Personality);
105   virtual void emitPersonalityIndex(unsigned Index);
106   virtual void emitHandlerData();
107   virtual void emitSetFP(unsigned FpReg, unsigned SpReg,
108                          int64_t Offset = 0);
109   virtual void emitMovSP(unsigned Reg, int64_t Offset = 0);
110   virtual void emitPad(int64_t Offset);
111   virtual void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
112                            bool isVector);
113   virtual void emitUnwindRaw(int64_t StackOffset,
114                              const SmallVectorImpl<uint8_t> &Opcodes);
115 
116   virtual void switchVendor(StringRef Vendor);
117   virtual void emitAttribute(unsigned Attribute, unsigned Value);
118   virtual void emitTextAttribute(unsigned Attribute, StringRef String);
119   virtual void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
120                                     StringRef StringValue = "");
121   virtual void emitFPU(unsigned FPU);
122   virtual void emitArch(unsigned Arch);
123   virtual void emitArchExtension(unsigned ArchExt);
124   virtual void emitObjectArch(unsigned Arch);
125   virtual void finishAttributeSection();
126   virtual void emitInst(uint32_t Inst, char Suffix = '\0');
127 
128   virtual void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE);
129 
130   virtual void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value);
131 
132   void finish() override;
133 
134   /// Reset any state between object emissions, i.e. the equivalent of
135   /// MCStreamer's reset method.
136   virtual void reset();
137 
138   /// Callback used to implement the ldr= pseudo.
139   /// Add a new entry to the constant pool for the current section and return an
140   /// MCExpr that can be used to refer to the constant pool location.
141   const MCExpr *addConstantPoolEntry(const MCExpr *, SMLoc Loc);
142 
143   /// Callback used to implemnt the .ltorg directive.
144   /// Emit contents of constant pool for the current section.
145   void emitCurrentConstantPool();
146 
147 private:
148   std::unique_ptr<AssemblerConstantPools> ConstantPools;
149 };
150 
151 /// \brief Streaming machine code generation interface.
152 ///
153 /// This interface is intended to provide a programatic interface that is very
154 /// similar to the level that an assembler .s file provides.  It has callbacks
155 /// to emit bytes, handle directives, etc.  The implementation of this interface
156 /// retains state to know what the current section is etc.
157 ///
158 /// There are multiple implementations of this interface: one for writing out
159 /// a .s file, and implementations that write out .o files of various formats.
160 ///
161 class MCStreamer {
162   MCContext &Context;
163   std::unique_ptr<MCTargetStreamer> TargetStreamer;
164 
165   MCStreamer(const MCStreamer &) = delete;
166   MCStreamer &operator=(const MCStreamer &) = delete;
167 
168   std::vector<MCDwarfFrameInfo> DwarfFrameInfos;
169   MCDwarfFrameInfo *getCurrentDwarfFrameInfo();
170   void EnsureValidDwarfFrame();
171 
172   MCSymbol *EmitCFICommon();
173 
174   std::vector<WinEH::FrameInfo *> WinFrameInfos;
175   WinEH::FrameInfo *CurrentWinFrameInfo;
176   void EnsureValidWinFrameInfo();
177 
178   /// \brief Tracks an index to represent the order a symbol was emitted in.
179   /// Zero means we did not emit that symbol.
180   DenseMap<const MCSymbol *, unsigned> SymbolOrdering;
181 
182   /// \brief This is stack of current and previous section values saved by
183   /// PushSection.
184   SmallVector<std::pair<MCSectionSubPair, MCSectionSubPair>, 4> SectionStack;
185 
186   /// The next unique ID to use when creating a WinCFI-related section (.pdata
187   /// or .xdata). This ID ensures that we have a one-to-one mapping from
188   /// code section to unwind info section, which MSVC's incremental linker
189   /// requires.
190   unsigned NextWinCFIID = 0;
191 
192 protected:
193   MCStreamer(MCContext &Ctx);
194 
195   virtual void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame);
196   virtual void EmitCFIEndProcImpl(MCDwarfFrameInfo &CurFrame);
197 
getCurrentWinFrameInfo()198   WinEH::FrameInfo *getCurrentWinFrameInfo() {
199     return CurrentWinFrameInfo;
200   }
201 
202   virtual void EmitWindowsUnwindTables();
203 
204   virtual void EmitRawTextImpl(StringRef String);
205 
206 public:
207   virtual ~MCStreamer();
208 
209   void visitUsedExpr(const MCExpr &Expr);
210   virtual void visitUsedSymbol(const MCSymbol &Sym);
211 
setTargetStreamer(MCTargetStreamer * TS)212   void setTargetStreamer(MCTargetStreamer *TS) {
213     TargetStreamer.reset(TS);
214   }
215 
216   /// State management
217   ///
218   virtual void reset();
219 
getContext()220   MCContext &getContext() const { return Context; }
221 
getTargetStreamer()222   MCTargetStreamer *getTargetStreamer() {
223     return TargetStreamer.get();
224   }
225 
getNumFrameInfos()226   unsigned getNumFrameInfos() { return DwarfFrameInfos.size(); }
getDwarfFrameInfos()227   ArrayRef<MCDwarfFrameInfo> getDwarfFrameInfos() const {
228     return DwarfFrameInfos;
229   }
230 
231   bool hasUnfinishedDwarfFrameInfo();
232 
getNumWinFrameInfos()233   unsigned getNumWinFrameInfos() { return WinFrameInfos.size(); }
getWinFrameInfos()234   ArrayRef<WinEH::FrameInfo *> getWinFrameInfos() const {
235     return WinFrameInfos;
236   }
237 
238   void generateCompactUnwindEncodings(MCAsmBackend *MAB);
239 
240   /// \name Assembly File Formatting.
241   /// @{
242 
243   /// \brief Return true if this streamer supports verbose assembly and if it is
244   /// enabled.
isVerboseAsm()245   virtual bool isVerboseAsm() const { return false; }
246 
247   /// \brief Return true if this asm streamer supports emitting unformatted text
248   /// to the .s file with EmitRawText.
hasRawTextSupport()249   virtual bool hasRawTextSupport() const { return false; }
250 
251   /// \brief Is the integrated assembler required for this streamer to function
252   /// correctly?
isIntegratedAssemblerRequired()253   virtual bool isIntegratedAssemblerRequired() const { return false; }
254 
255   /// \brief Add a textual comment.
256   ///
257   /// Typically for comments that can be emitted to the generated .s
258   /// file if applicable as a QoI issue to make the output of the compiler
259   /// more readable.  This only affects the MCAsmStreamer, and only when
260   /// verbose assembly output is enabled.
261   ///
262   /// If the comment includes embedded \n's, they will each get the comment
263   /// prefix as appropriate.  The added comment should not end with a \n.
AddComment(const Twine & T)264   virtual void AddComment(const Twine &T) {}
265 
266   /// \brief Return a raw_ostream that comments can be written to. Unlike
267   /// AddComment, you are required to terminate comments with \n if you use this
268   /// method.
269   virtual raw_ostream &GetCommentOS();
270 
271   /// \brief Print T and prefix it with the comment string (normally #) and
272   /// optionally a tab. This prints the comment immediately, not at the end of
273   /// the current line. It is basically a safe version of EmitRawText: since it
274   /// only prints comments, the object streamer ignores it instead of asserting.
275   virtual void emitRawComment(const Twine &T, bool TabPrefix = true);
276 
277   /// \brief Add explicit comment T. T is required to be a valid
278   /// comment in the output and does not need to be escaped.
279   virtual void addExplicitComment(const Twine &T);
280   /// \brief Emit added explicit comments.
281   virtual void emitExplicitComments();
282 
283   /// AddBlankLine - Emit a blank line to a .s file to pretty it up.
AddBlankLine()284   virtual void AddBlankLine() {}
285 
286   /// @}
287 
288   /// \name Symbol & Section Management
289   /// @{
290 
291   /// \brief Return the current section that the streamer is emitting code to.
getCurrentSection()292   MCSectionSubPair getCurrentSection() const {
293     if (!SectionStack.empty())
294       return SectionStack.back().first;
295     return MCSectionSubPair();
296   }
getCurrentSectionOnly()297   MCSection *getCurrentSectionOnly() const { return getCurrentSection().first; }
298 
299   /// \brief Return the previous section that the streamer is emitting code to.
getPreviousSection()300   MCSectionSubPair getPreviousSection() const {
301     if (!SectionStack.empty())
302       return SectionStack.back().second;
303     return MCSectionSubPair();
304   }
305 
306   /// \brief Returns an index to represent the order a symbol was emitted in.
307   /// (zero if we did not emit that symbol)
GetSymbolOrder(const MCSymbol * Sym)308   unsigned GetSymbolOrder(const MCSymbol *Sym) const {
309     return SymbolOrdering.lookup(Sym);
310   }
311 
312   /// \brief Update streamer for a new active section.
313   ///
314   /// This is called by PopSection and SwitchSection, if the current
315   /// section changes.
316   virtual void ChangeSection(MCSection *, const MCExpr *);
317 
318   /// \brief Save the current and previous section on the section stack.
PushSection()319   void PushSection() {
320     SectionStack.push_back(
321         std::make_pair(getCurrentSection(), getPreviousSection()));
322   }
323 
324   /// \brief Restore the current and previous section from the section stack.
325   /// Calls ChangeSection as needed.
326   ///
327   /// Returns false if the stack was empty.
PopSection()328   bool PopSection() {
329     if (SectionStack.size() <= 1)
330       return false;
331     auto I = SectionStack.end();
332     --I;
333     MCSectionSubPair OldSection = I->first;
334     --I;
335     MCSectionSubPair NewSection = I->first;
336 
337     if (OldSection != NewSection)
338       ChangeSection(NewSection.first, NewSection.second);
339     SectionStack.pop_back();
340     return true;
341   }
342 
SubSection(const MCExpr * Subsection)343   bool SubSection(const MCExpr *Subsection) {
344     if (SectionStack.empty())
345       return false;
346 
347     SwitchSection(SectionStack.back().first.first, Subsection);
348     return true;
349   }
350 
351   /// Set the current section where code is being emitted to \p Section.  This
352   /// is required to update CurSection.
353   ///
354   /// This corresponds to assembler directives like .section, .text, etc.
355   virtual void SwitchSection(MCSection *Section,
356                              const MCExpr *Subsection = nullptr);
357 
358   /// \brief Set the current section where code is being emitted to \p Section.
359   /// This is required to update CurSection. This version does not call
360   /// ChangeSection.
361   void SwitchSectionNoChange(MCSection *Section,
362                              const MCExpr *Subsection = nullptr) {
363     assert(Section && "Cannot switch to a null section!");
364     MCSectionSubPair curSection = SectionStack.back().first;
365     SectionStack.back().second = curSection;
366     if (MCSectionSubPair(Section, Subsection) != curSection)
367       SectionStack.back().first = MCSectionSubPair(Section, Subsection);
368   }
369 
370   /// \brief Create the default sections and set the initial one.
371   virtual void InitSections(bool NoExecStack);
372 
373   MCSymbol *endSection(MCSection *Section);
374 
375   /// \brief Sets the symbol's section.
376   ///
377   /// Each emitted symbol will be tracked in the ordering table,
378   /// so we can sort on them later.
379   void AssignFragment(MCSymbol *Symbol, MCFragment *Fragment);
380 
381   /// \brief Emit a label for \p Symbol into the current section.
382   ///
383   /// This corresponds to an assembler statement such as:
384   ///   foo:
385   ///
386   /// \param Symbol - The symbol to emit. A given symbol should only be
387   /// emitted as a label once, and symbols emitted as a label should never be
388   /// used in an assignment.
389   // FIXME: These emission are non-const because we mutate the symbol to
390   // add the section we're emitting it to later.
391   virtual void EmitLabel(MCSymbol *Symbol);
392 
393   virtual void EmitEHSymAttributes(const MCSymbol *Symbol, MCSymbol *EHSymbol);
394 
395   /// \brief Note in the output the specified \p Flag.
396   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
397 
398   /// \brief Emit the given list \p Options of strings as linker
399   /// options into the output.
EmitLinkerOptions(ArrayRef<std::string> Kind)400   virtual void EmitLinkerOptions(ArrayRef<std::string> Kind) {}
401 
402   /// \brief Note in the output the specified region \p Kind.
EmitDataRegion(MCDataRegionType Kind)403   virtual void EmitDataRegion(MCDataRegionType Kind) {}
404 
405   /// \brief Specify the MachO minimum deployment target version.
EmitVersionMin(MCVersionMinType,unsigned Major,unsigned Minor,unsigned Update)406   virtual void EmitVersionMin(MCVersionMinType, unsigned Major, unsigned Minor,
407                               unsigned Update) {}
408 
409   /// \brief Note in the output that the specified \p Func is a Thumb mode
410   /// function (ARM target only).
411   virtual void EmitThumbFunc(MCSymbol *Func);
412 
413   /// \brief Emit an assignment of \p Value to \p Symbol.
414   ///
415   /// This corresponds to an assembler statement such as:
416   ///  symbol = value
417   ///
418   /// The assignment generates no code, but has the side effect of binding the
419   /// value in the current context. For the assembly streamer, this prints the
420   /// binding into the .s file.
421   ///
422   /// \param Symbol - The symbol being assigned to.
423   /// \param Value - The value for the symbol.
424   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
425 
426   /// \brief Emit an weak reference from \p Alias to \p Symbol.
427   ///
428   /// This corresponds to an assembler statement such as:
429   ///  .weakref alias, symbol
430   ///
431   /// \param Alias - The alias that is being created.
432   /// \param Symbol - The symbol being aliased.
433   virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
434 
435   /// \brief Add the given \p Attribute to \p Symbol.
436   virtual bool EmitSymbolAttribute(MCSymbol *Symbol,
437                                    MCSymbolAttr Attribute) = 0;
438 
439   /// \brief Set the \p DescValue for the \p Symbol.
440   ///
441   /// \param Symbol - The symbol to have its n_desc field set.
442   /// \param DescValue - The value to set into the n_desc field.
443   virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
444 
445   /// \brief Start emitting COFF symbol definition
446   ///
447   /// \param Symbol - The symbol to have its External & Type fields set.
448   virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol);
449 
450   /// \brief Emit the storage class of the symbol.
451   ///
452   /// \param StorageClass - The storage class the symbol should have.
453   virtual void EmitCOFFSymbolStorageClass(int StorageClass);
454 
455   /// \brief Emit the type of the symbol.
456   ///
457   /// \param Type - A COFF type identifier (see COFF::SymbolType in X86COFF.h)
458   virtual void EmitCOFFSymbolType(int Type);
459 
460   /// \brief Marks the end of the symbol definition.
461   virtual void EndCOFFSymbolDef();
462 
463   virtual void EmitCOFFSafeSEH(MCSymbol const *Symbol);
464 
465   /// \brief Emits a COFF section index.
466   ///
467   /// \param Symbol - Symbol the section number relocation should point to.
468   virtual void EmitCOFFSectionIndex(MCSymbol const *Symbol);
469 
470   /// \brief Emits a COFF section relative relocation.
471   ///
472   /// \param Symbol - Symbol the section relative relocation should point to.
473   virtual void EmitCOFFSecRel32(MCSymbol const *Symbol);
474 
475   /// \brief Emit an ELF .size directive.
476   ///
477   /// This corresponds to an assembler statement such as:
478   ///  .size symbol, expression
479   virtual void emitELFSize(MCSymbolELF *Symbol, const MCExpr *Value);
480 
481   /// \brief Emit a Linker Optimization Hint (LOH) directive.
482   /// \param Args - Arguments of the LOH.
EmitLOHDirective(MCLOHType Kind,const MCLOHArgs & Args)483   virtual void EmitLOHDirective(MCLOHType Kind, const MCLOHArgs &Args) {}
484 
485   /// \brief Emit a common symbol.
486   ///
487   /// \param Symbol - The common symbol to emit.
488   /// \param Size - The size of the common symbol.
489   /// \param ByteAlignment - The alignment of the symbol if
490   /// non-zero. This must be a power of 2.
491   virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
492                                 unsigned ByteAlignment) = 0;
493 
494   /// \brief Emit a local common (.lcomm) symbol.
495   ///
496   /// \param Symbol - The common symbol to emit.
497   /// \param Size - The size of the common symbol.
498   /// \param ByteAlignment - The alignment of the common symbol in bytes.
499   virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
500                                      unsigned ByteAlignment);
501 
502   /// \brief Emit the zerofill section and an optional symbol.
503   ///
504   /// \param Section - The zerofill section to create and or to put the symbol
505   /// \param Symbol - The zerofill symbol to emit, if non-NULL.
506   /// \param Size - The size of the zerofill symbol.
507   /// \param ByteAlignment - The alignment of the zerofill symbol if
508   /// non-zero. This must be a power of 2 on some targets.
509   virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
510                             uint64_t Size = 0, unsigned ByteAlignment = 0) = 0;
511 
512   /// \brief Emit a thread local bss (.tbss) symbol.
513   ///
514   /// \param Section - The thread local common section.
515   /// \param Symbol - The thread local common symbol to emit.
516   /// \param Size - The size of the symbol.
517   /// \param ByteAlignment - The alignment of the thread local common symbol
518   /// if non-zero.  This must be a power of 2 on some targets.
519   virtual void EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
520                               uint64_t Size, unsigned ByteAlignment = 0);
521 
522   /// @}
523   /// \name Generating Data
524   /// @{
525 
526   /// \brief Emit the bytes in \p Data into the output.
527   ///
528   /// This is used to implement assembler directives such as .byte, .ascii,
529   /// etc.
530   virtual void EmitBytes(StringRef Data);
531 
532   /// Functionally identical to EmitBytes. When emitting textual assembly, this
533   /// method uses .byte directives instead of .ascii or .asciz for readability.
534   virtual void EmitBinaryData(StringRef Data);
535 
536   /// \brief Emit the expression \p Value into the output as a native
537   /// integer of the given \p Size bytes.
538   ///
539   /// This is used to implement assembler directives such as .word, .quad,
540   /// etc.
541   ///
542   /// \param Value - The value to emit.
543   /// \param Size - The size of the integer (in bytes) to emit. This must
544   /// match a native machine width.
545   /// \param Loc - The location of the expression for error reporting.
546   virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
547                              SMLoc Loc = SMLoc());
548 
549   void EmitValue(const MCExpr *Value, unsigned Size, SMLoc Loc = SMLoc());
550 
551   /// \brief Special case of EmitValue that avoids the client having
552   /// to pass in a MCExpr for constant integers.
553   virtual void EmitIntValue(uint64_t Value, unsigned Size);
554 
555   virtual void EmitULEB128Value(const MCExpr *Value);
556 
557   virtual void EmitSLEB128Value(const MCExpr *Value);
558 
559   /// \brief Special case of EmitULEB128Value that avoids the client having to
560   /// pass in a MCExpr for constant integers.
561   void EmitULEB128IntValue(uint64_t Value, unsigned Padding = 0);
562 
563   /// \brief Special case of EmitSLEB128Value that avoids the client having to
564   /// pass in a MCExpr for constant integers.
565   void EmitSLEB128IntValue(int64_t Value);
566 
567   /// \brief Special case of EmitValue that avoids the client having to pass in
568   /// a MCExpr for MCSymbols.
569   void EmitSymbolValue(const MCSymbol *Sym, unsigned Size,
570                        bool IsSectionRelative = false);
571 
572   /// \brief Emit the expression \p Value into the output as a gprel64 (64-bit
573   /// GP relative) value.
574   ///
575   /// This is used to implement assembler directives such as .gpdword on
576   /// targets that support them.
577   virtual void EmitGPRel64Value(const MCExpr *Value);
578 
579   /// \brief Emit the expression \p Value into the output as a gprel32 (32-bit
580   /// GP relative) value.
581   ///
582   /// This is used to implement assembler directives such as .gprel32 on
583   /// targets that support them.
584   virtual void EmitGPRel32Value(const MCExpr *Value);
585 
586   /// \brief Emit NumBytes bytes worth of the value specified by FillValue.
587   /// This implements directives such as '.space'.
588   virtual void emitFill(uint64_t NumBytes, uint8_t FillValue);
589 
590   /// \brief Emit \p Size bytes worth of the value specified by \p FillValue.
591   ///
592   /// This is used to implement assembler directives such as .space or .skip.
593   ///
594   /// \param NumBytes - The number of bytes to emit.
595   /// \param FillValue - The value to use when filling bytes.
596   /// \param Loc - The location of the expression for error reporting.
597   virtual void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
598                         SMLoc Loc = SMLoc());
599 
600   /// \brief Emit \p NumValues copies of \p Size bytes. Each \p Size bytes is
601   /// taken from the lowest order 4 bytes of \p Expr expression.
602   ///
603   /// This is used to implement assembler directives such as .fill.
604   ///
605   /// \param NumValues - The number of copies of \p Size bytes to emit.
606   /// \param Size - The size (in bytes) of each repeated value.
607   /// \param Expr - The expression from which \p Size bytes are used.
608   virtual void emitFill(uint64_t NumValues, int64_t Size, int64_t Expr);
609   virtual void emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
610                         SMLoc Loc = SMLoc());
611 
612   /// \brief Emit NumBytes worth of zeros.
613   /// This function properly handles data in virtual sections.
614   void EmitZeros(uint64_t NumBytes);
615 
616   /// \brief Emit some number of copies of \p Value until the byte alignment \p
617   /// ByteAlignment is reached.
618   ///
619   /// If the number of bytes need to emit for the alignment is not a multiple
620   /// of \p ValueSize, then the contents of the emitted fill bytes is
621   /// undefined.
622   ///
623   /// This used to implement the .align assembler directive.
624   ///
625   /// \param ByteAlignment - The alignment to reach. This must be a power of
626   /// two on some targets.
627   /// \param Value - The value to use when filling bytes.
628   /// \param ValueSize - The size of the integer (in bytes) to emit for
629   /// \p Value. This must match a native machine width.
630   /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
631   /// the alignment cannot be reached in this many bytes, no bytes are
632   /// emitted.
633   virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
634                                     unsigned ValueSize = 1,
635                                     unsigned MaxBytesToEmit = 0);
636 
637   /// \brief Emit nops until the byte alignment \p ByteAlignment is reached.
638   ///
639   /// This used to align code where the alignment bytes may be executed.  This
640   /// can emit different bytes for different sizes to optimize execution.
641   ///
642   /// \param ByteAlignment - The alignment to reach. This must be a power of
643   /// two on some targets.
644   /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If
645   /// the alignment cannot be reached in this many bytes, no bytes are
646   /// emitted.
647   virtual void EmitCodeAlignment(unsigned ByteAlignment,
648                                  unsigned MaxBytesToEmit = 0);
649 
650   /// \brief Emit some number of copies of \p Value until the byte offset \p
651   /// Offset is reached.
652   ///
653   /// This is used to implement assembler directives such as .org.
654   ///
655   /// \param Offset - The offset to reach. This may be an expression, but the
656   /// expression must be associated with the current section.
657   /// \param Value - The value to use when filling bytes.
658   virtual void emitValueToOffset(const MCExpr *Offset, unsigned char Value = 0);
659 
660   /// @}
661 
662   /// \brief Switch to a new logical file.  This is used to implement the '.file
663   /// "foo.c"' assembler directive.
664   virtual void EmitFileDirective(StringRef Filename);
665 
666   /// \brief Emit the "identifiers" directive.  This implements the
667   /// '.ident "version foo"' assembler directive.
EmitIdent(StringRef IdentString)668   virtual void EmitIdent(StringRef IdentString) {}
669 
670   /// \brief Associate a filename with a specified logical file number.  This
671   /// implements the DWARF2 '.file 4 "foo.c"' assembler directive.
672   virtual unsigned EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
673                                           StringRef Filename,
674                                           unsigned CUID = 0);
675 
676   /// \brief This implements the DWARF2 '.loc fileno lineno ...' assembler
677   /// directive.
678   virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
679                                      unsigned Column, unsigned Flags,
680                                      unsigned Isa, unsigned Discriminator,
681                                      StringRef FileName);
682 
683   /// \brief Associate a filename with a specified logical file number.  This
684   /// implements the '.cv_file 4 "foo.c"' assembler directive.
685   virtual unsigned EmitCVFileDirective(unsigned FileNo, StringRef Filename);
686 
687   /// \brief This implements the CodeView '.cv_loc' assembler directive.
688   virtual void EmitCVLocDirective(unsigned FunctionId, unsigned FileNo,
689                                   unsigned Line, unsigned Column,
690                                   bool PrologueEnd, bool IsStmt,
691                                   StringRef FileName);
692 
693   /// \brief This implements the CodeView '.cv_linetable' assembler directive.
694   virtual void EmitCVLinetableDirective(unsigned FunctionId,
695                                         const MCSymbol *FnStart,
696                                         const MCSymbol *FnEnd);
697 
698   /// \brief This implements the CodeView '.cv_inline_linetable' assembler
699   /// directive.
700   virtual void EmitCVInlineLinetableDirective(
701       unsigned PrimaryFunctionId, unsigned SourceFileId, unsigned SourceLineNum,
702       const MCSymbol *FnStartSym, const MCSymbol *FnEndSym,
703       ArrayRef<unsigned> SecondaryFunctionIds);
704 
705   /// \brief This implements the CodeView '.cv_def_range' assembler
706   /// directive.
707   virtual void EmitCVDefRangeDirective(
708       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
709       StringRef FixedSizePortion);
710 
711   /// \brief This implements the CodeView '.cv_stringtable' assembler directive.
EmitCVStringTableDirective()712   virtual void EmitCVStringTableDirective() {}
713 
714   /// \brief This implements the CodeView '.cv_filechecksums' assembler directive.
EmitCVFileChecksumsDirective()715   virtual void EmitCVFileChecksumsDirective() {}
716 
717   /// Emit the absolute difference between two symbols.
718   ///
719   /// \pre Offset of \c Hi is greater than the offset \c Lo.
720   virtual void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
721                                       unsigned Size);
722 
723   virtual MCSymbol *getDwarfLineTableSymbol(unsigned CUID);
724   virtual void EmitCFISections(bool EH, bool Debug);
725   void EmitCFIStartProc(bool IsSimple);
726   void EmitCFIEndProc();
727   virtual void EmitCFIDefCfa(int64_t Register, int64_t Offset);
728   virtual void EmitCFIDefCfaOffset(int64_t Offset);
729   virtual void EmitCFIDefCfaRegister(int64_t Register);
730   virtual void EmitCFIOffset(int64_t Register, int64_t Offset);
731   virtual void EmitCFIPersonality(const MCSymbol *Sym, unsigned Encoding);
732   virtual void EmitCFILsda(const MCSymbol *Sym, unsigned Encoding);
733   virtual void EmitCFIRememberState();
734   virtual void EmitCFIRestoreState();
735   virtual void EmitCFISameValue(int64_t Register);
736   virtual void EmitCFIRestore(int64_t Register);
737   virtual void EmitCFIRelOffset(int64_t Register, int64_t Offset);
738   virtual void EmitCFIAdjustCfaOffset(int64_t Adjustment);
739   virtual void EmitCFIEscape(StringRef Values);
740   virtual void EmitCFIGnuArgsSize(int64_t Size);
741   virtual void EmitCFISignalFrame();
742   virtual void EmitCFIUndefined(int64_t Register);
743   virtual void EmitCFIRegister(int64_t Register1, int64_t Register2);
744   virtual void EmitCFIWindowSave();
745 
746   virtual void EmitWinCFIStartProc(const MCSymbol *Symbol);
747   virtual void EmitWinCFIEndProc();
748   virtual void EmitWinCFIStartChained();
749   virtual void EmitWinCFIEndChained();
750   virtual void EmitWinCFIPushReg(unsigned Register);
751   virtual void EmitWinCFISetFrame(unsigned Register, unsigned Offset);
752   virtual void EmitWinCFIAllocStack(unsigned Size);
753   virtual void EmitWinCFISaveReg(unsigned Register, unsigned Offset);
754   virtual void EmitWinCFISaveXMM(unsigned Register, unsigned Offset);
755   virtual void EmitWinCFIPushFrame(bool Code);
756   virtual void EmitWinCFIEndProlog();
757 
758   virtual void EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except);
759   virtual void EmitWinEHHandlerData();
760 
761   /// Get the .pdata section used for the given section. Typically the given
762   /// section is either the main .text section or some other COMDAT .text
763   /// section, but it may be any section containing code.
764   MCSection *getAssociatedPDataSection(const MCSection *TextSec);
765 
766   /// Get the .xdata section used for the given section.
767   MCSection *getAssociatedXDataSection(const MCSection *TextSec);
768 
769   virtual void EmitSyntaxDirective();
770 
771   /// \brief Emit a .reloc directive.
772   /// Returns true if the relocation could not be emitted because Name is not
773   /// known.
EmitRelocDirective(const MCExpr & Offset,StringRef Name,const MCExpr * Expr,SMLoc Loc)774   virtual bool EmitRelocDirective(const MCExpr &Offset, StringRef Name,
775                                   const MCExpr *Expr, SMLoc Loc) {
776     return true;
777   }
778 
779   /// \brief Emit the given \p Instruction into the current section.
780   virtual void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI);
781 
782   /// \brief Set the bundle alignment mode from now on in the section.
783   /// The argument is the power of 2 to which the alignment is set. The
784   /// value 0 means turn the bundle alignment off.
785   virtual void EmitBundleAlignMode(unsigned AlignPow2);
786 
787   /// \brief The following instructions are a bundle-locked group.
788   ///
789   /// \param AlignToEnd - If true, the bundle-locked group will be aligned to
790   ///                     the end of a bundle.
791   virtual void EmitBundleLock(bool AlignToEnd);
792 
793   /// \brief Ends a bundle-locked group.
794   virtual void EmitBundleUnlock();
795 
796   /// \brief If this file is backed by a assembly streamer, this dumps the
797   /// specified string in the output .s file.  This capability is indicated by
798   /// the hasRawTextSupport() predicate.  By default this aborts.
799   void EmitRawText(const Twine &String);
800 
801   /// \brief Streamer specific finalization.
802   virtual void FinishImpl();
803   /// \brief Finish emission of machine code.
804   void Finish();
805 
mayHaveInstructions(MCSection & Sec)806   virtual bool mayHaveInstructions(MCSection &Sec) const { return true; }
807 };
808 
809 /// Create a dummy machine code streamer, which does nothing. This is useful for
810 /// timing the assembler front end.
811 MCStreamer *createNullStreamer(MCContext &Ctx);
812 
813 /// Create a machine code streamer which will print out assembly for the native
814 /// target, suitable for compiling with a native assembler.
815 ///
816 /// \param InstPrint - If given, the instruction printer to use. If not given
817 /// the MCInst representation will be printed.  This method takes ownership of
818 /// InstPrint.
819 ///
820 /// \param CE - If given, a code emitter to use to show the instruction
821 /// encoding inline with the assembly. This method takes ownership of \p CE.
822 ///
823 /// \param TAB - If given, a target asm backend to use to show the fixup
824 /// information in conjunction with encoding information. This method takes
825 /// ownership of \p TAB.
826 ///
827 /// \param ShowInst - Whether to show the MCInst representation inline with
828 /// the assembly.
829 MCStreamer *createAsmStreamer(MCContext &Ctx,
830                               std::unique_ptr<formatted_raw_ostream> OS,
831                               bool isVerboseAsm, bool useDwarfDirectory,
832                               MCInstPrinter *InstPrint, MCCodeEmitter *CE,
833                               MCAsmBackend *TAB, bool ShowInst);
834 } // end namespace llvm
835 
836 #endif
837