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/APInt.h" 17 #include "llvm/ADT/ArrayRef.h" 18 #include "llvm/ADT/DenseMap.h" 19 #include "llvm/ADT/Optional.h" 20 #include "llvm/ADT/SmallVector.h" 21 #include "llvm/ADT/StringRef.h" 22 #include "llvm/MC/MCDirectives.h" 23 #include "llvm/MC/MCLinkerOptimizationHint.h" 24 #include "llvm/MC/MCPseudoProbe.h" 25 #include "llvm/MC/MCSymbol.h" 26 #include "llvm/MC/MCWinEH.h" 27 #include "llvm/Support/Error.h" 28 #include "llvm/Support/MD5.h" 29 #include "llvm/Support/SMLoc.h" 30 #include "llvm/Support/TargetParser.h" 31 #include "llvm/Support/VersionTuple.h" 32 #include <cassert> 33 #include <cstdint> 34 #include <memory> 35 #include <string> 36 #include <utility> 37 #include <vector> 38 39 namespace llvm { 40 41 class AssemblerConstantPools; 42 class formatted_raw_ostream; 43 class MCAsmBackend; 44 class MCCodeEmitter; 45 class MCContext; 46 struct MCDwarfFrameInfo; 47 class MCExpr; 48 class MCInst; 49 class MCInstPrinter; 50 class MCRegister; 51 class MCSection; 52 class MCStreamer; 53 class MCSymbolRefExpr; 54 class MCSubtargetInfo; 55 class raw_ostream; 56 class Twine; 57 58 namespace codeview { 59 struct DefRangeRegisterRelHeader; 60 struct DefRangeSubfieldRegisterHeader; 61 struct DefRangeRegisterHeader; 62 struct DefRangeFramePointerRelHeader; 63 } 64 65 using MCSectionSubPair = std::pair<MCSection *, const MCExpr *>; 66 67 /// Target specific streamer interface. This is used so that targets can 68 /// implement support for target specific assembly directives. 69 /// 70 /// If target foo wants to use this, it should implement 3 classes: 71 /// * FooTargetStreamer : public MCTargetStreamer 72 /// * FooTargetAsmStreamer : public FooTargetStreamer 73 /// * FooTargetELFStreamer : public FooTargetStreamer 74 /// 75 /// FooTargetStreamer should have a pure virtual method for each directive. For 76 /// example, for a ".bar symbol_name" directive, it should have 77 /// virtual emitBar(const MCSymbol &Symbol) = 0; 78 /// 79 /// The FooTargetAsmStreamer and FooTargetELFStreamer classes implement the 80 /// method. The assembly streamer just prints ".bar symbol_name". The object 81 /// streamer does whatever is needed to implement .bar in the object file. 82 /// 83 /// In the assembly printer and parser the target streamer can be used by 84 /// calling getTargetStreamer and casting it to FooTargetStreamer: 85 /// 86 /// MCTargetStreamer &TS = OutStreamer.getTargetStreamer(); 87 /// FooTargetStreamer &ATS = static_cast<FooTargetStreamer &>(TS); 88 /// 89 /// The base classes FooTargetAsmStreamer and FooTargetELFStreamer should 90 /// *never* be treated differently. Callers should always talk to a 91 /// FooTargetStreamer. 92 class MCTargetStreamer { 93 protected: 94 MCStreamer &Streamer; 95 96 public: 97 MCTargetStreamer(MCStreamer &S); 98 virtual ~MCTargetStreamer(); 99 getStreamer()100 MCStreamer &getStreamer() { return Streamer; } 101 102 // Allow a target to add behavior to the EmitLabel of MCStreamer. 103 virtual void emitLabel(MCSymbol *Symbol); 104 // Allow a target to add behavior to the emitAssignment of MCStreamer. 105 virtual void emitAssignment(MCSymbol *Symbol, const MCExpr *Value); 106 107 virtual void prettyPrintAsm(MCInstPrinter &InstPrinter, uint64_t Address, 108 const MCInst &Inst, const MCSubtargetInfo &STI, 109 raw_ostream &OS); 110 111 virtual void emitDwarfFileDirective(StringRef Directive); 112 113 /// Update streamer for a new active section. 114 /// 115 /// This is called by PopSection and SwitchSection, if the current 116 /// section changes. 117 virtual void changeSection(const MCSection *CurSection, MCSection *Section, 118 const MCExpr *SubSection, raw_ostream &OS); 119 120 virtual void emitValue(const MCExpr *Value); 121 122 /// Emit the bytes in \p Data into the output. 123 /// 124 /// This is used to emit bytes in \p Data as sequence of .byte directives. 125 virtual void emitRawBytes(StringRef Data); 126 127 virtual void finish(); 128 }; 129 130 // FIXME: declared here because it is used from 131 // lib/CodeGen/AsmPrinter/ARMException.cpp. 132 class ARMTargetStreamer : public MCTargetStreamer { 133 public: 134 ARMTargetStreamer(MCStreamer &S); 135 ~ARMTargetStreamer() override; 136 137 virtual void emitFnStart(); 138 virtual void emitFnEnd(); 139 virtual void emitCantUnwind(); 140 virtual void emitPersonality(const MCSymbol *Personality); 141 virtual void emitPersonalityIndex(unsigned Index); 142 virtual void emitHandlerData(); 143 virtual void emitSetFP(unsigned FpReg, unsigned SpReg, 144 int64_t Offset = 0); 145 virtual void emitMovSP(unsigned Reg, int64_t Offset = 0); 146 virtual void emitPad(int64_t Offset); 147 virtual void emitRegSave(const SmallVectorImpl<unsigned> &RegList, 148 bool isVector); 149 virtual void emitUnwindRaw(int64_t StackOffset, 150 const SmallVectorImpl<uint8_t> &Opcodes); 151 152 virtual void switchVendor(StringRef Vendor); 153 virtual void emitAttribute(unsigned Attribute, unsigned Value); 154 virtual void emitTextAttribute(unsigned Attribute, StringRef String); 155 virtual void emitIntTextAttribute(unsigned Attribute, unsigned IntValue, 156 StringRef StringValue = ""); 157 virtual void emitFPU(unsigned FPU); 158 virtual void emitArch(ARM::ArchKind Arch); 159 virtual void emitArchExtension(uint64_t ArchExt); 160 virtual void emitObjectArch(ARM::ArchKind Arch); 161 void emitTargetAttributes(const MCSubtargetInfo &STI); 162 virtual void finishAttributeSection(); 163 virtual void emitInst(uint32_t Inst, char Suffix = '\0'); 164 165 virtual void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE); 166 167 virtual void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value); 168 169 void finish() override; 170 171 /// Reset any state between object emissions, i.e. the equivalent of 172 /// MCStreamer's reset method. 173 virtual void reset(); 174 175 /// Callback used to implement the ldr= pseudo. 176 /// Add a new entry to the constant pool for the current section and return an 177 /// MCExpr that can be used to refer to the constant pool location. 178 const MCExpr *addConstantPoolEntry(const MCExpr *, SMLoc Loc); 179 180 /// Callback used to implemnt the .ltorg directive. 181 /// Emit contents of constant pool for the current section. 182 void emitCurrentConstantPool(); 183 184 private: 185 std::unique_ptr<AssemblerConstantPools> ConstantPools; 186 }; 187 188 /// Streaming machine code generation interface. 189 /// 190 /// This interface is intended to provide a programatic interface that is very 191 /// similar to the level that an assembler .s file provides. It has callbacks 192 /// to emit bytes, handle directives, etc. The implementation of this interface 193 /// retains state to know what the current section is etc. 194 /// 195 /// There are multiple implementations of this interface: one for writing out 196 /// a .s file, and implementations that write out .o files of various formats. 197 /// 198 class MCStreamer { 199 MCContext &Context; 200 std::unique_ptr<MCTargetStreamer> TargetStreamer; 201 202 std::vector<MCDwarfFrameInfo> DwarfFrameInfos; 203 MCDwarfFrameInfo *getCurrentDwarfFrameInfo(); 204 205 /// Similar to DwarfFrameInfos, but for SEH unwind info. Chained frames may 206 /// refer to each other, so use std::unique_ptr to provide pointer stability. 207 std::vector<std::unique_ptr<WinEH::FrameInfo>> WinFrameInfos; 208 209 WinEH::FrameInfo *CurrentWinFrameInfo; 210 size_t CurrentProcWinFrameInfoStartIndex; 211 212 /// Tracks an index to represent the order a symbol was emitted in. 213 /// Zero means we did not emit that symbol. 214 DenseMap<const MCSymbol *, unsigned> SymbolOrdering; 215 216 /// This is stack of current and previous section values saved by 217 /// PushSection. 218 SmallVector<std::pair<MCSectionSubPair, MCSectionSubPair>, 4> SectionStack; 219 220 /// Pointer to the parser's SMLoc if available. This is used to provide 221 /// locations for diagnostics. 222 const SMLoc *StartTokLocPtr = nullptr; 223 224 /// The next unique ID to use when creating a WinCFI-related section (.pdata 225 /// or .xdata). This ID ensures that we have a one-to-one mapping from 226 /// code section to unwind info section, which MSVC's incremental linker 227 /// requires. 228 unsigned NextWinCFIID = 0; 229 230 bool UseAssemblerInfoForParsing; 231 232 /// Is the assembler allowed to insert padding automatically? For 233 /// correctness reasons, we sometimes need to ensure instructions aren't 234 /// seperated in unexpected ways. At the moment, this feature is only 235 /// useable from an integrated assembler, but assembly syntax is under 236 /// discussion for future inclusion. 237 bool AllowAutoPadding = false; 238 239 protected: 240 MCStreamer(MCContext &Ctx); 241 242 virtual void emitCFIStartProcImpl(MCDwarfFrameInfo &Frame); 243 virtual void emitCFIEndProcImpl(MCDwarfFrameInfo &CurFrame); 244 getCurrentWinFrameInfo()245 WinEH::FrameInfo *getCurrentWinFrameInfo() { 246 return CurrentWinFrameInfo; 247 } 248 249 virtual void EmitWindowsUnwindTables(WinEH::FrameInfo *Frame); 250 251 virtual void EmitWindowsUnwindTables(); 252 253 virtual void emitRawTextImpl(StringRef String); 254 255 /// Returns true if the the .cv_loc directive is in the right section. 256 bool checkCVLocSection(unsigned FuncId, unsigned FileNo, SMLoc Loc); 257 258 public: 259 MCStreamer(const MCStreamer &) = delete; 260 MCStreamer &operator=(const MCStreamer &) = delete; 261 virtual ~MCStreamer(); 262 263 void visitUsedExpr(const MCExpr &Expr); 264 virtual void visitUsedSymbol(const MCSymbol &Sym); 265 setTargetStreamer(MCTargetStreamer * TS)266 void setTargetStreamer(MCTargetStreamer *TS) { 267 TargetStreamer.reset(TS); 268 } 269 setStartTokLocPtr(const SMLoc * Loc)270 void setStartTokLocPtr(const SMLoc *Loc) { StartTokLocPtr = Loc; } getStartTokLoc()271 SMLoc getStartTokLoc() const { 272 return StartTokLocPtr ? *StartTokLocPtr : SMLoc(); 273 } 274 275 /// State management 276 /// 277 virtual void reset(); 278 getContext()279 MCContext &getContext() const { return Context; } 280 getAssemblerPtr()281 virtual MCAssembler *getAssemblerPtr() { return nullptr; } 282 setUseAssemblerInfoForParsing(bool v)283 void setUseAssemblerInfoForParsing(bool v) { UseAssemblerInfoForParsing = v; } getUseAssemblerInfoForParsing()284 bool getUseAssemblerInfoForParsing() { return UseAssemblerInfoForParsing; } 285 getTargetStreamer()286 MCTargetStreamer *getTargetStreamer() { 287 return TargetStreamer.get(); 288 } 289 setAllowAutoPadding(bool v)290 void setAllowAutoPadding(bool v) { AllowAutoPadding = v; } getAllowAutoPadding()291 bool getAllowAutoPadding() const { return AllowAutoPadding; } 292 293 /// When emitting an object file, create and emit a real label. When emitting 294 /// textual assembly, this should do nothing to avoid polluting our output. 295 virtual MCSymbol *emitCFILabel(); 296 297 /// Retreive the current frame info if one is available and it is not yet 298 /// closed. Otherwise, issue an error and return null. 299 WinEH::FrameInfo *EnsureValidWinFrameInfo(SMLoc Loc); 300 301 unsigned getNumFrameInfos(); 302 ArrayRef<MCDwarfFrameInfo> getDwarfFrameInfos() const; 303 304 bool hasUnfinishedDwarfFrameInfo(); 305 getNumWinFrameInfos()306 unsigned getNumWinFrameInfos() { return WinFrameInfos.size(); } getWinFrameInfos()307 ArrayRef<std::unique_ptr<WinEH::FrameInfo>> getWinFrameInfos() const { 308 return WinFrameInfos; 309 } 310 311 void generateCompactUnwindEncodings(MCAsmBackend *MAB); 312 313 /// \name Assembly File Formatting. 314 /// @{ 315 316 /// Return true if this streamer supports verbose assembly and if it is 317 /// enabled. isVerboseAsm()318 virtual bool isVerboseAsm() const { return false; } 319 320 /// Return true if this asm streamer supports emitting unformatted text 321 /// to the .s file with EmitRawText. hasRawTextSupport()322 virtual bool hasRawTextSupport() const { return false; } 323 324 /// Is the integrated assembler required for this streamer to function 325 /// correctly? isIntegratedAssemblerRequired()326 virtual bool isIntegratedAssemblerRequired() const { return false; } 327 328 /// Add a textual comment. 329 /// 330 /// Typically for comments that can be emitted to the generated .s 331 /// file if applicable as a QoI issue to make the output of the compiler 332 /// more readable. This only affects the MCAsmStreamer, and only when 333 /// verbose assembly output is enabled. 334 /// 335 /// If the comment includes embedded \n's, they will each get the comment 336 /// prefix as appropriate. The added comment should not end with a \n. 337 /// By default, each comment is terminated with an end of line, i.e. the 338 /// EOL param is set to true by default. If one prefers not to end the 339 /// comment with a new line then the EOL param should be passed 340 /// with a false value. 341 virtual void AddComment(const Twine &T, bool EOL = true) {} 342 343 /// Return a raw_ostream that comments can be written to. Unlike 344 /// AddComment, you are required to terminate comments with \n if you use this 345 /// method. 346 virtual raw_ostream &GetCommentOS(); 347 348 /// Print T and prefix it with the comment string (normally #) and 349 /// optionally a tab. This prints the comment immediately, not at the end of 350 /// the current line. It is basically a safe version of EmitRawText: since it 351 /// only prints comments, the object streamer ignores it instead of asserting. 352 virtual void emitRawComment(const Twine &T, bool TabPrefix = true); 353 354 /// Add explicit comment T. T is required to be a valid 355 /// comment in the output and does not need to be escaped. 356 virtual void addExplicitComment(const Twine &T); 357 358 /// Emit added explicit comments. 359 virtual void emitExplicitComments(); 360 361 /// AddBlankLine - Emit a blank line to a .s file to pretty it up. AddBlankLine()362 virtual void AddBlankLine() {} 363 364 /// @} 365 366 /// \name Symbol & Section Management 367 /// @{ 368 369 /// Return the current section that the streamer is emitting code to. getCurrentSection()370 MCSectionSubPair getCurrentSection() const { 371 if (!SectionStack.empty()) 372 return SectionStack.back().first; 373 return MCSectionSubPair(); 374 } getCurrentSectionOnly()375 MCSection *getCurrentSectionOnly() const { return getCurrentSection().first; } 376 377 /// Return the previous section that the streamer is emitting code to. getPreviousSection()378 MCSectionSubPair getPreviousSection() const { 379 if (!SectionStack.empty()) 380 return SectionStack.back().second; 381 return MCSectionSubPair(); 382 } 383 384 /// Returns an index to represent the order a symbol was emitted in. 385 /// (zero if we did not emit that symbol) GetSymbolOrder(const MCSymbol * Sym)386 unsigned GetSymbolOrder(const MCSymbol *Sym) const { 387 return SymbolOrdering.lookup(Sym); 388 } 389 390 /// Update streamer for a new active section. 391 /// 392 /// This is called by PopSection and SwitchSection, if the current 393 /// section changes. 394 virtual void changeSection(MCSection *, const MCExpr *); 395 396 /// Save the current and previous section on the section stack. PushSection()397 void PushSection() { 398 SectionStack.push_back( 399 std::make_pair(getCurrentSection(), getPreviousSection())); 400 } 401 402 /// Restore the current and previous section from the section stack. 403 /// Calls changeSection as needed. 404 /// 405 /// Returns false if the stack was empty. PopSection()406 bool PopSection() { 407 if (SectionStack.size() <= 1) 408 return false; 409 auto I = SectionStack.end(); 410 --I; 411 MCSectionSubPair OldSection = I->first; 412 --I; 413 MCSectionSubPair NewSection = I->first; 414 415 if (NewSection.first && OldSection != NewSection) 416 changeSection(NewSection.first, NewSection.second); 417 SectionStack.pop_back(); 418 return true; 419 } 420 SubSection(const MCExpr * Subsection)421 bool SubSection(const MCExpr *Subsection) { 422 if (SectionStack.empty()) 423 return false; 424 425 SwitchSection(SectionStack.back().first.first, Subsection); 426 return true; 427 } 428 429 /// Set the current section where code is being emitted to \p Section. This 430 /// is required to update CurSection. 431 /// 432 /// This corresponds to assembler directives like .section, .text, etc. 433 virtual void SwitchSection(MCSection *Section, 434 const MCExpr *Subsection = nullptr); 435 436 /// Set the current section where code is being emitted to \p Section. 437 /// This is required to update CurSection. This version does not call 438 /// changeSection. 439 void SwitchSectionNoChange(MCSection *Section, 440 const MCExpr *Subsection = nullptr) { 441 assert(Section && "Cannot switch to a null section!"); 442 MCSectionSubPair curSection = SectionStack.back().first; 443 SectionStack.back().second = curSection; 444 if (MCSectionSubPair(Section, Subsection) != curSection) 445 SectionStack.back().first = MCSectionSubPair(Section, Subsection); 446 } 447 448 /// Create the default sections and set the initial one. 449 virtual void InitSections(bool NoExecStack); 450 451 MCSymbol *endSection(MCSection *Section); 452 453 /// Sets the symbol's section. 454 /// 455 /// Each emitted symbol will be tracked in the ordering table, 456 /// so we can sort on them later. 457 void AssignFragment(MCSymbol *Symbol, MCFragment *Fragment); 458 459 /// Returns the mnemonic for \p MI, if the streamer has access to a 460 /// instruction printer and returns an empty string otherwise. getMnemonic(MCInst & MI)461 virtual StringRef getMnemonic(MCInst &MI) { return ""; } 462 463 /// Emit a label for \p Symbol into the current section. 464 /// 465 /// This corresponds to an assembler statement such as: 466 /// foo: 467 /// 468 /// \param Symbol - The symbol to emit. A given symbol should only be 469 /// emitted as a label once, and symbols emitted as a label should never be 470 /// used in an assignment. 471 // FIXME: These emission are non-const because we mutate the symbol to 472 // add the section we're emitting it to later. 473 virtual void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()); 474 475 virtual void emitEHSymAttributes(const MCSymbol *Symbol, MCSymbol *EHSymbol); 476 477 /// Note in the output the specified \p Flag. 478 virtual void emitAssemblerFlag(MCAssemblerFlag Flag); 479 480 /// Emit the given list \p Options of strings as linker 481 /// options into the output. emitLinkerOptions(ArrayRef<std::string> Kind)482 virtual void emitLinkerOptions(ArrayRef<std::string> Kind) {} 483 484 /// Note in the output the specified region \p Kind. emitDataRegion(MCDataRegionType Kind)485 virtual void emitDataRegion(MCDataRegionType Kind) {} 486 487 /// Specify the Mach-O minimum deployment target version. emitVersionMin(MCVersionMinType Type,unsigned Major,unsigned Minor,unsigned Update,VersionTuple SDKVersion)488 virtual void emitVersionMin(MCVersionMinType Type, unsigned Major, 489 unsigned Minor, unsigned Update, 490 VersionTuple SDKVersion) {} 491 492 /// Emit/Specify Mach-O build version command. 493 /// \p Platform should be one of MachO::PlatformType. emitBuildVersion(unsigned Platform,unsigned Major,unsigned Minor,unsigned Update,VersionTuple SDKVersion)494 virtual void emitBuildVersion(unsigned Platform, unsigned Major, 495 unsigned Minor, unsigned Update, 496 VersionTuple SDKVersion) {} 497 498 void emitVersionForTarget(const Triple &Target, 499 const VersionTuple &SDKVersion); 500 501 /// Note in the output that the specified \p Func is a Thumb mode 502 /// function (ARM target only). 503 virtual void emitThumbFunc(MCSymbol *Func); 504 505 /// Emit an assignment of \p Value to \p Symbol. 506 /// 507 /// This corresponds to an assembler statement such as: 508 /// symbol = value 509 /// 510 /// The assignment generates no code, but has the side effect of binding the 511 /// value in the current context. For the assembly streamer, this prints the 512 /// binding into the .s file. 513 /// 514 /// \param Symbol - The symbol being assigned to. 515 /// \param Value - The value for the symbol. 516 virtual void emitAssignment(MCSymbol *Symbol, const MCExpr *Value); 517 518 /// Emit an weak reference from \p Alias to \p Symbol. 519 /// 520 /// This corresponds to an assembler statement such as: 521 /// .weakref alias, symbol 522 /// 523 /// \param Alias - The alias that is being created. 524 /// \param Symbol - The symbol being aliased. 525 virtual void emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol); 526 527 /// Add the given \p Attribute to \p Symbol. 528 virtual bool emitSymbolAttribute(MCSymbol *Symbol, 529 MCSymbolAttr Attribute) = 0; 530 531 /// Set the \p DescValue for the \p Symbol. 532 /// 533 /// \param Symbol - The symbol to have its n_desc field set. 534 /// \param DescValue - The value to set into the n_desc field. 535 virtual void emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue); 536 537 /// Start emitting COFF symbol definition 538 /// 539 /// \param Symbol - The symbol to have its External & Type fields set. 540 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol); 541 542 /// Emit the storage class of the symbol. 543 /// 544 /// \param StorageClass - The storage class the symbol should have. 545 virtual void EmitCOFFSymbolStorageClass(int StorageClass); 546 547 /// Emit the type of the symbol. 548 /// 549 /// \param Type - A COFF type identifier (see COFF::SymbolType in X86COFF.h) 550 virtual void EmitCOFFSymbolType(int Type); 551 552 /// Marks the end of the symbol definition. 553 virtual void EndCOFFSymbolDef(); 554 555 virtual void EmitCOFFSafeSEH(MCSymbol const *Symbol); 556 557 /// Emits the symbol table index of a Symbol into the current section. 558 virtual void EmitCOFFSymbolIndex(MCSymbol const *Symbol); 559 560 /// Emits a COFF section index. 561 /// 562 /// \param Symbol - Symbol the section number relocation should point to. 563 virtual void EmitCOFFSectionIndex(MCSymbol const *Symbol); 564 565 /// Emits a COFF section relative relocation. 566 /// 567 /// \param Symbol - Symbol the section relative relocation should point to. 568 virtual void EmitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset); 569 570 /// Emits a COFF image relative relocation. 571 /// 572 /// \param Symbol - Symbol the image relative relocation should point to. 573 virtual void EmitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset); 574 575 /// Emits an lcomm directive with XCOFF csect information. 576 /// 577 /// \param LabelSym - Label on the block of storage. 578 /// \param Size - The size of the block of storage. 579 /// \param CsectSym - Csect name for the block of storage. 580 /// \param ByteAlignment - The alignment of the symbol in bytes. Must be a 581 /// power of 2. 582 virtual void emitXCOFFLocalCommonSymbol(MCSymbol *LabelSym, uint64_t Size, 583 MCSymbol *CsectSym, 584 unsigned ByteAlignment); 585 586 /// Emit a symbol's linkage and visibilty with a linkage directive for XCOFF. 587 /// 588 /// \param Symbol - The symbol to emit. 589 /// \param Linkage - The linkage of the symbol to emit. 590 /// \param Visibility - The visibility of the symbol to emit or MCSA_Invalid 591 /// if the symbol does not have an explicit visibility. 592 virtual void emitXCOFFSymbolLinkageWithVisibility(MCSymbol *Symbol, 593 MCSymbolAttr Linkage, 594 MCSymbolAttr Visibility); 595 596 /// Emit a XCOFF .rename directive which creates a synonym for an illegal or 597 /// undesirable name. 598 /// 599 /// \param Name - The name used internally in the assembly for references to 600 /// the symbol. 601 /// \param Rename - The value to which the Name parameter is 602 /// changed at the end of assembly. 603 virtual void emitXCOFFRenameDirective(const MCSymbol *Name, StringRef Rename); 604 605 /// Emit an ELF .size directive. 606 /// 607 /// This corresponds to an assembler statement such as: 608 /// .size symbol, expression 609 virtual void emitELFSize(MCSymbol *Symbol, const MCExpr *Value); 610 611 /// Emit an ELF .symver directive. 612 /// 613 /// This corresponds to an assembler statement such as: 614 /// .symver _start, foo@@SOME_VERSION 615 /// \param AliasName - The versioned alias (i.e. "foo@@SOME_VERSION") 616 /// \param Aliasee - The aliased symbol (i.e. "_start") 617 virtual void emitELFSymverDirective(StringRef AliasName, 618 const MCSymbol *Aliasee); 619 620 /// Emit a Linker Optimization Hint (LOH) directive. 621 /// \param Args - Arguments of the LOH. emitLOHDirective(MCLOHType Kind,const MCLOHArgs & Args)622 virtual void emitLOHDirective(MCLOHType Kind, const MCLOHArgs &Args) {} 623 624 /// Emit a common symbol. 625 /// 626 /// \param Symbol - The common symbol to emit. 627 /// \param Size - The size of the common symbol. 628 /// \param ByteAlignment - The alignment of the symbol if 629 /// non-zero. This must be a power of 2. 630 virtual void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size, 631 unsigned ByteAlignment) = 0; 632 633 /// Emit a local common (.lcomm) symbol. 634 /// 635 /// \param Symbol - The common symbol to emit. 636 /// \param Size - The size of the common symbol. 637 /// \param ByteAlignment - The alignment of the common symbol in bytes. 638 virtual void emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size, 639 unsigned ByteAlignment); 640 641 /// Emit the zerofill section and an optional symbol. 642 /// 643 /// \param Section - The zerofill section to create and or to put the symbol 644 /// \param Symbol - The zerofill symbol to emit, if non-NULL. 645 /// \param Size - The size of the zerofill symbol. 646 /// \param ByteAlignment - The alignment of the zerofill symbol if 647 /// non-zero. This must be a power of 2 on some targets. 648 virtual void emitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr, 649 uint64_t Size = 0, unsigned ByteAlignment = 0, 650 SMLoc Loc = SMLoc()) = 0; 651 652 /// Emit a thread local bss (.tbss) symbol. 653 /// 654 /// \param Section - The thread local common section. 655 /// \param Symbol - The thread local common symbol to emit. 656 /// \param Size - The size of the symbol. 657 /// \param ByteAlignment - The alignment of the thread local common symbol 658 /// if non-zero. This must be a power of 2 on some targets. 659 virtual void emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol, 660 uint64_t Size, unsigned ByteAlignment = 0); 661 662 /// @} 663 /// \name Generating Data 664 /// @{ 665 666 /// Emit the bytes in \p Data into the output. 667 /// 668 /// This is used to implement assembler directives such as .byte, .ascii, 669 /// etc. 670 virtual void emitBytes(StringRef Data); 671 672 /// Functionally identical to EmitBytes. When emitting textual assembly, this 673 /// method uses .byte directives instead of .ascii or .asciz for readability. 674 virtual void emitBinaryData(StringRef Data); 675 676 /// Emit the expression \p Value into the output as a native 677 /// integer of the given \p Size bytes. 678 /// 679 /// This is used to implement assembler directives such as .word, .quad, 680 /// etc. 681 /// 682 /// \param Value - The value to emit. 683 /// \param Size - The size of the integer (in bytes) to emit. This must 684 /// match a native machine width. 685 /// \param Loc - The location of the expression for error reporting. 686 virtual void emitValueImpl(const MCExpr *Value, unsigned Size, 687 SMLoc Loc = SMLoc()); 688 689 void emitValue(const MCExpr *Value, unsigned Size, SMLoc Loc = SMLoc()); 690 691 /// Special case of EmitValue that avoids the client having 692 /// to pass in a MCExpr for constant integers. 693 virtual void emitIntValue(uint64_t Value, unsigned Size); 694 virtual void emitIntValue(APInt Value); 695 696 /// Special case of EmitValue that avoids the client having to pass 697 /// in a MCExpr for constant integers & prints in Hex format for certain 698 /// modes. emitIntValueInHex(uint64_t Value,unsigned Size)699 virtual void emitIntValueInHex(uint64_t Value, unsigned Size) { 700 emitIntValue(Value, Size); 701 } 702 emitInt8(uint64_t Value)703 void emitInt8(uint64_t Value) { emitIntValue(Value, 1); } emitInt16(uint64_t Value)704 void emitInt16(uint64_t Value) { emitIntValue(Value, 2); } emitInt32(uint64_t Value)705 void emitInt32(uint64_t Value) { emitIntValue(Value, 4); } emitInt64(uint64_t Value)706 void emitInt64(uint64_t Value) { emitIntValue(Value, 8); } 707 708 /// Special case of EmitValue that avoids the client having to pass 709 /// in a MCExpr for constant integers & prints in Hex format for certain 710 /// modes, pads the field with leading zeros to Size width emitIntValueInHexWithPadding(uint64_t Value,unsigned Size)711 virtual void emitIntValueInHexWithPadding(uint64_t Value, unsigned Size) { 712 emitIntValue(Value, Size); 713 } 714 715 virtual void emitULEB128Value(const MCExpr *Value); 716 717 virtual void emitSLEB128Value(const MCExpr *Value); 718 719 /// Special case of EmitULEB128Value that avoids the client having to 720 /// pass in a MCExpr for constant integers. 721 void emitULEB128IntValue(uint64_t Value, unsigned PadTo = 0); 722 723 /// Special case of EmitSLEB128Value that avoids the client having to 724 /// pass in a MCExpr for constant integers. 725 void emitSLEB128IntValue(int64_t Value); 726 727 /// Special case of EmitValue that avoids the client having to pass in 728 /// a MCExpr for MCSymbols. 729 void emitSymbolValue(const MCSymbol *Sym, unsigned Size, 730 bool IsSectionRelative = false); 731 732 /// Emit the expression \p Value into the output as a dtprel 733 /// (64-bit DTP relative) value. 734 /// 735 /// This is used to implement assembler directives such as .dtpreldword on 736 /// targets that support them. 737 virtual void emitDTPRel64Value(const MCExpr *Value); 738 739 /// Emit the expression \p Value into the output as a dtprel 740 /// (32-bit DTP relative) value. 741 /// 742 /// This is used to implement assembler directives such as .dtprelword on 743 /// targets that support them. 744 virtual void emitDTPRel32Value(const MCExpr *Value); 745 746 /// Emit the expression \p Value into the output as a tprel 747 /// (64-bit TP relative) value. 748 /// 749 /// This is used to implement assembler directives such as .tpreldword on 750 /// targets that support them. 751 virtual void emitTPRel64Value(const MCExpr *Value); 752 753 /// Emit the expression \p Value into the output as a tprel 754 /// (32-bit TP relative) value. 755 /// 756 /// This is used to implement assembler directives such as .tprelword on 757 /// targets that support them. 758 virtual void emitTPRel32Value(const MCExpr *Value); 759 760 /// Emit the expression \p Value into the output as a gprel64 (64-bit 761 /// GP relative) value. 762 /// 763 /// This is used to implement assembler directives such as .gpdword on 764 /// targets that support them. 765 virtual void emitGPRel64Value(const MCExpr *Value); 766 767 /// Emit the expression \p Value into the output as a gprel32 (32-bit 768 /// GP relative) value. 769 /// 770 /// This is used to implement assembler directives such as .gprel32 on 771 /// targets that support them. 772 virtual void emitGPRel32Value(const MCExpr *Value); 773 774 /// Emit NumBytes bytes worth of the value specified by FillValue. 775 /// This implements directives such as '.space'. 776 void emitFill(uint64_t NumBytes, uint8_t FillValue); 777 778 /// Emit \p Size bytes worth of the value specified by \p FillValue. 779 /// 780 /// This is used to implement assembler directives such as .space or .skip. 781 /// 782 /// \param NumBytes - The number of bytes to emit. 783 /// \param FillValue - The value to use when filling bytes. 784 /// \param Loc - The location of the expression for error reporting. 785 virtual void emitFill(const MCExpr &NumBytes, uint64_t FillValue, 786 SMLoc Loc = SMLoc()); 787 788 /// Emit \p NumValues copies of \p Size bytes. Each \p Size bytes is 789 /// taken from the lowest order 4 bytes of \p Expr expression. 790 /// 791 /// This is used to implement assembler directives such as .fill. 792 /// 793 /// \param NumValues - The number of copies of \p Size bytes to emit. 794 /// \param Size - The size (in bytes) of each repeated value. 795 /// \param Expr - The expression from which \p Size bytes are used. 796 virtual void emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr, 797 SMLoc Loc = SMLoc()); 798 799 virtual void emitNops(int64_t NumBytes, int64_t ControlledNopLength, 800 SMLoc Loc); 801 802 /// Emit NumBytes worth of zeros. 803 /// This function properly handles data in virtual sections. 804 void emitZeros(uint64_t NumBytes); 805 806 /// Emit some number of copies of \p Value until the byte alignment \p 807 /// ByteAlignment is reached. 808 /// 809 /// If the number of bytes need to emit for the alignment is not a multiple 810 /// of \p ValueSize, then the contents of the emitted fill bytes is 811 /// undefined. 812 /// 813 /// This used to implement the .align assembler directive. 814 /// 815 /// \param ByteAlignment - The alignment to reach. This must be a power of 816 /// two on some targets. 817 /// \param Value - The value to use when filling bytes. 818 /// \param ValueSize - The size of the integer (in bytes) to emit for 819 /// \p Value. This must match a native machine width. 820 /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If 821 /// the alignment cannot be reached in this many bytes, no bytes are 822 /// emitted. 823 virtual void emitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0, 824 unsigned ValueSize = 1, 825 unsigned MaxBytesToEmit = 0); 826 827 /// Emit nops until the byte alignment \p ByteAlignment is reached. 828 /// 829 /// This used to align code where the alignment bytes may be executed. This 830 /// can emit different bytes for different sizes to optimize execution. 831 /// 832 /// \param ByteAlignment - The alignment to reach. This must be a power of 833 /// two on some targets. 834 /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If 835 /// the alignment cannot be reached in this many bytes, no bytes are 836 /// emitted. 837 virtual void emitCodeAlignment(unsigned ByteAlignment, 838 unsigned MaxBytesToEmit = 0); 839 840 /// Emit some number of copies of \p Value until the byte offset \p 841 /// Offset is reached. 842 /// 843 /// This is used to implement assembler directives such as .org. 844 /// 845 /// \param Offset - The offset to reach. This may be an expression, but the 846 /// expression must be associated with the current section. 847 /// \param Value - The value to use when filling bytes. 848 virtual void emitValueToOffset(const MCExpr *Offset, unsigned char Value, 849 SMLoc Loc); 850 851 /// @} 852 853 /// Switch to a new logical file. This is used to implement the '.file 854 /// "foo.c"' assembler directive. 855 virtual void emitFileDirective(StringRef Filename); 856 857 /// Emit the "identifiers" directive. This implements the 858 /// '.ident "version foo"' assembler directive. emitIdent(StringRef IdentString)859 virtual void emitIdent(StringRef IdentString) {} 860 861 /// Associate a filename with a specified logical file number. This 862 /// implements the DWARF2 '.file 4 "foo.c"' assembler directive. 863 unsigned emitDwarfFileDirective(unsigned FileNo, StringRef Directory, 864 StringRef Filename, 865 Optional<MD5::MD5Result> Checksum = None, 866 Optional<StringRef> Source = None, 867 unsigned CUID = 0) { 868 return cantFail( 869 tryEmitDwarfFileDirective(FileNo, Directory, Filename, Checksum, 870 Source, CUID)); 871 } 872 873 /// Associate a filename with a specified logical file number. 874 /// Also associate a directory, optional checksum, and optional source 875 /// text with the logical file. This implements the DWARF2 876 /// '.file 4 "dir/foo.c"' assembler directive, and the DWARF5 877 /// '.file 4 "dir/foo.c" md5 "..." source "..."' assembler directive. 878 virtual Expected<unsigned> tryEmitDwarfFileDirective( 879 unsigned FileNo, StringRef Directory, StringRef Filename, 880 Optional<MD5::MD5Result> Checksum = None, Optional<StringRef> Source = None, 881 unsigned CUID = 0); 882 883 /// Specify the "root" file of the compilation, using the ".file 0" extension. 884 virtual void emitDwarfFile0Directive(StringRef Directory, StringRef Filename, 885 Optional<MD5::MD5Result> Checksum, 886 Optional<StringRef> Source, 887 unsigned CUID = 0); 888 889 virtual void emitCFIBKeyFrame(); 890 891 /// This implements the DWARF2 '.loc fileno lineno ...' assembler 892 /// directive. 893 virtual void emitDwarfLocDirective(unsigned FileNo, unsigned Line, 894 unsigned Column, unsigned Flags, 895 unsigned Isa, unsigned Discriminator, 896 StringRef FileName); 897 898 /// Associate a filename with a specified logical file number, and also 899 /// specify that file's checksum information. This implements the '.cv_file 4 900 /// "foo.c"' assembler directive. Returns true on success. 901 virtual bool EmitCVFileDirective(unsigned FileNo, StringRef Filename, 902 ArrayRef<uint8_t> Checksum, 903 unsigned ChecksumKind); 904 905 /// Introduces a function id for use with .cv_loc. 906 virtual bool EmitCVFuncIdDirective(unsigned FunctionId); 907 908 /// Introduces an inline call site id for use with .cv_loc. Includes 909 /// extra information for inline line table generation. 910 virtual bool EmitCVInlineSiteIdDirective(unsigned FunctionId, unsigned IAFunc, 911 unsigned IAFile, unsigned IALine, 912 unsigned IACol, SMLoc Loc); 913 914 /// This implements the CodeView '.cv_loc' assembler directive. 915 virtual void emitCVLocDirective(unsigned FunctionId, unsigned FileNo, 916 unsigned Line, unsigned Column, 917 bool PrologueEnd, bool IsStmt, 918 StringRef FileName, SMLoc Loc); 919 920 /// This implements the CodeView '.cv_linetable' assembler directive. 921 virtual void emitCVLinetableDirective(unsigned FunctionId, 922 const MCSymbol *FnStart, 923 const MCSymbol *FnEnd); 924 925 /// This implements the CodeView '.cv_inline_linetable' assembler 926 /// directive. 927 virtual void emitCVInlineLinetableDirective(unsigned PrimaryFunctionId, 928 unsigned SourceFileId, 929 unsigned SourceLineNum, 930 const MCSymbol *FnStartSym, 931 const MCSymbol *FnEndSym); 932 933 /// This implements the CodeView '.cv_def_range' assembler 934 /// directive. 935 virtual void emitCVDefRangeDirective( 936 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 937 StringRef FixedSizePortion); 938 939 virtual void emitCVDefRangeDirective( 940 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 941 codeview::DefRangeRegisterRelHeader DRHdr); 942 943 virtual void emitCVDefRangeDirective( 944 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 945 codeview::DefRangeSubfieldRegisterHeader DRHdr); 946 947 virtual void emitCVDefRangeDirective( 948 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 949 codeview::DefRangeRegisterHeader DRHdr); 950 951 virtual void emitCVDefRangeDirective( 952 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 953 codeview::DefRangeFramePointerRelHeader DRHdr); 954 955 /// This implements the CodeView '.cv_stringtable' assembler directive. emitCVStringTableDirective()956 virtual void emitCVStringTableDirective() {} 957 958 /// This implements the CodeView '.cv_filechecksums' assembler directive. emitCVFileChecksumsDirective()959 virtual void emitCVFileChecksumsDirective() {} 960 961 /// This implements the CodeView '.cv_filechecksumoffset' assembler 962 /// directive. emitCVFileChecksumOffsetDirective(unsigned FileNo)963 virtual void emitCVFileChecksumOffsetDirective(unsigned FileNo) {} 964 965 /// This implements the CodeView '.cv_fpo_data' assembler directive. 966 virtual void EmitCVFPOData(const MCSymbol *ProcSym, SMLoc Loc = {}) {} 967 968 /// Emit the absolute difference between two symbols. 969 /// 970 /// \pre Offset of \c Hi is greater than the offset \c Lo. 971 virtual void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo, 972 unsigned Size); 973 974 /// Emit the absolute difference between two symbols encoded with ULEB128. 975 virtual void emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi, 976 const MCSymbol *Lo); 977 978 virtual MCSymbol *getDwarfLineTableSymbol(unsigned CUID); 979 virtual void emitCFISections(bool EH, bool Debug); 980 void emitCFIStartProc(bool IsSimple, SMLoc Loc = SMLoc()); 981 void emitCFIEndProc(); 982 virtual void emitCFIDefCfa(int64_t Register, int64_t Offset); 983 virtual void emitCFIDefCfaOffset(int64_t Offset); 984 virtual void emitCFIDefCfaRegister(int64_t Register); 985 virtual void emitCFIOffset(int64_t Register, int64_t Offset); 986 virtual void emitCFIPersonality(const MCSymbol *Sym, unsigned Encoding); 987 virtual void emitCFILsda(const MCSymbol *Sym, unsigned Encoding); 988 virtual void emitCFIRememberState(); 989 virtual void emitCFIRestoreState(); 990 virtual void emitCFISameValue(int64_t Register); 991 virtual void emitCFIRestore(int64_t Register); 992 virtual void emitCFIRelOffset(int64_t Register, int64_t Offset); 993 virtual void emitCFIAdjustCfaOffset(int64_t Adjustment); 994 virtual void emitCFIEscape(StringRef Values); 995 virtual void emitCFIReturnColumn(int64_t Register); 996 virtual void emitCFIGnuArgsSize(int64_t Size); 997 virtual void emitCFISignalFrame(); 998 virtual void emitCFIUndefined(int64_t Register); 999 virtual void emitCFIRegister(int64_t Register1, int64_t Register2); 1000 virtual void emitCFIWindowSave(); 1001 virtual void emitCFINegateRAState(); 1002 1003 virtual void EmitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc = SMLoc()); 1004 virtual void EmitWinCFIEndProc(SMLoc Loc = SMLoc()); 1005 /// This is used on platforms, such as Windows on ARM64, that require function 1006 /// or funclet sizes to be emitted in .xdata before the End marker is emitted 1007 /// for the frame. We cannot use the End marker, as it is not set at the 1008 /// point of emitting .xdata, in order to indicate that the frame is active. 1009 virtual void EmitWinCFIFuncletOrFuncEnd(SMLoc Loc = SMLoc()); 1010 virtual void EmitWinCFIStartChained(SMLoc Loc = SMLoc()); 1011 virtual void EmitWinCFIEndChained(SMLoc Loc = SMLoc()); 1012 virtual void EmitWinCFIPushReg(MCRegister Register, SMLoc Loc = SMLoc()); 1013 virtual void EmitWinCFISetFrame(MCRegister Register, unsigned Offset, 1014 SMLoc Loc = SMLoc()); 1015 virtual void EmitWinCFIAllocStack(unsigned Size, SMLoc Loc = SMLoc()); 1016 virtual void EmitWinCFISaveReg(MCRegister Register, unsigned Offset, 1017 SMLoc Loc = SMLoc()); 1018 virtual void EmitWinCFISaveXMM(MCRegister Register, unsigned Offset, 1019 SMLoc Loc = SMLoc()); 1020 virtual void EmitWinCFIPushFrame(bool Code, SMLoc Loc = SMLoc()); 1021 virtual void EmitWinCFIEndProlog(SMLoc Loc = SMLoc()); 1022 virtual void EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except, 1023 SMLoc Loc = SMLoc()); 1024 virtual void EmitWinEHHandlerData(SMLoc Loc = SMLoc()); 1025 1026 virtual void emitCGProfileEntry(const MCSymbolRefExpr *From, 1027 const MCSymbolRefExpr *To, uint64_t Count); 1028 1029 /// Get the .pdata section used for the given section. Typically the given 1030 /// section is either the main .text section or some other COMDAT .text 1031 /// section, but it may be any section containing code. 1032 MCSection *getAssociatedPDataSection(const MCSection *TextSec); 1033 1034 /// Get the .xdata section used for the given section. 1035 MCSection *getAssociatedXDataSection(const MCSection *TextSec); 1036 1037 virtual void emitSyntaxDirective(); 1038 1039 /// Record a relocation described by the .reloc directive. Return None if 1040 /// succeeded. Otherwise, return a pair (Name is invalid, error message). 1041 virtual Optional<std::pair<bool, std::string>> emitRelocDirective(const MCExpr & Offset,StringRef Name,const MCExpr * Expr,SMLoc Loc,const MCSubtargetInfo & STI)1042 emitRelocDirective(const MCExpr &Offset, StringRef Name, const MCExpr *Expr, 1043 SMLoc Loc, const MCSubtargetInfo &STI) { 1044 return None; 1045 } 1046 emitAddrsig()1047 virtual void emitAddrsig() {} emitAddrsigSym(const MCSymbol * Sym)1048 virtual void emitAddrsigSym(const MCSymbol *Sym) {} 1049 1050 /// Emit the given \p Instruction into the current section. 1051 virtual void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI); 1052 1053 /// Emit the a pseudo probe into the current section. 1054 virtual void emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type, 1055 uint64_t Attr, 1056 const MCPseudoProbeInlineStack &InlineStack); 1057 1058 /// Set the bundle alignment mode from now on in the section. 1059 /// The argument is the power of 2 to which the alignment is set. The 1060 /// value 0 means turn the bundle alignment off. 1061 virtual void emitBundleAlignMode(unsigned AlignPow2); 1062 1063 /// The following instructions are a bundle-locked group. 1064 /// 1065 /// \param AlignToEnd - If true, the bundle-locked group will be aligned to 1066 /// the end of a bundle. 1067 virtual void emitBundleLock(bool AlignToEnd); 1068 1069 /// Ends a bundle-locked group. 1070 virtual void emitBundleUnlock(); 1071 1072 /// If this file is backed by a assembly streamer, this dumps the 1073 /// specified string in the output .s file. This capability is indicated by 1074 /// the hasRawTextSupport() predicate. By default this aborts. 1075 void emitRawText(const Twine &String); 1076 1077 /// Streamer specific finalization. 1078 virtual void finishImpl(); 1079 /// Finish emission of machine code. 1080 void Finish(SMLoc EndLoc = SMLoc()); 1081 mayHaveInstructions(MCSection & Sec)1082 virtual bool mayHaveInstructions(MCSection &Sec) const { return true; } 1083 }; 1084 1085 /// Create a dummy machine code streamer, which does nothing. This is useful for 1086 /// timing the assembler front end. 1087 MCStreamer *createNullStreamer(MCContext &Ctx); 1088 1089 } // end namespace llvm 1090 1091 #endif // LLVM_MC_MCSTREAMER_H 1092