1 //===- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework ---------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file contains a class to be used as the base class for target specific 10 // asm writers. This class primarily handles common functionality used by 11 // all asm writers. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_CODEGEN_ASMPRINTER_H 16 #define LLVM_CODEGEN_ASMPRINTER_H 17 18 #include "llvm/ADT/MapVector.h" 19 #include "llvm/ADT/SmallVector.h" 20 #include "llvm/CodeGen/AsmPrinterHandler.h" 21 #include "llvm/CodeGen/DwarfStringPoolEntry.h" 22 #include "llvm/CodeGen/MachineFunctionPass.h" 23 #include "llvm/IR/InlineAsm.h" 24 #include "llvm/IR/LLVMContext.h" 25 #include "llvm/Support/ErrorHandling.h" 26 #include "llvm/Support/SourceMgr.h" 27 #include <cstdint> 28 #include <memory> 29 #include <utility> 30 #include <vector> 31 32 namespace llvm { 33 34 class BasicBlock; 35 class BlockAddress; 36 class Constant; 37 class ConstantArray; 38 class DataLayout; 39 class DIE; 40 class DIEAbbrev; 41 class DwarfDebug; 42 class GCMetadataPrinter; 43 class GCStrategy; 44 class GlobalIndirectSymbol; 45 class GlobalObject; 46 class GlobalValue; 47 class GlobalVariable; 48 class MachineBasicBlock; 49 class MachineConstantPoolValue; 50 class MachineDominatorTree; 51 class MachineFunction; 52 class MachineInstr; 53 class MachineJumpTableInfo; 54 class MachineLoopInfo; 55 class MachineModuleInfo; 56 class MachineOptimizationRemarkEmitter; 57 class MCAsmInfo; 58 class MCCFIInstruction; 59 class MCContext; 60 class MCExpr; 61 class MCInst; 62 class MCSection; 63 class MCStreamer; 64 class MCSubtargetInfo; 65 class MCSymbol; 66 class MCTargetOptions; 67 class MDNode; 68 class Module; 69 class PseudoProbeHandler; 70 class raw_ostream; 71 class StackMaps; 72 class StringRef; 73 class TargetLoweringObjectFile; 74 class TargetMachine; 75 class Twine; 76 77 namespace remarks { 78 class RemarkStreamer; 79 } 80 81 /// This class is intended to be used as a driving class for all asm writers. 82 class AsmPrinter : public MachineFunctionPass { 83 public: 84 /// Target machine description. 85 TargetMachine &TM; 86 87 /// Target Asm Printer information. 88 const MCAsmInfo *MAI; 89 90 /// This is the context for the output file that we are streaming. This owns 91 /// all of the global MC-related objects for the generated translation unit. 92 MCContext &OutContext; 93 94 /// This is the MCStreamer object for the file we are generating. This 95 /// contains the transient state for the current translation unit that we are 96 /// generating (such as the current section etc). 97 std::unique_ptr<MCStreamer> OutStreamer; 98 99 /// The current machine function. 100 MachineFunction *MF = nullptr; 101 102 /// This is a pointer to the current MachineModuleInfo. 103 MachineModuleInfo *MMI = nullptr; 104 105 /// This is a pointer to the current MachineDominatorTree. 106 MachineDominatorTree *MDT = nullptr; 107 108 /// This is a pointer to the current MachineLoopInfo. 109 MachineLoopInfo *MLI = nullptr; 110 111 /// Optimization remark emitter. 112 MachineOptimizationRemarkEmitter *ORE; 113 114 /// The symbol for the entry in __patchable_function_entires. 115 MCSymbol *CurrentPatchableFunctionEntrySym = nullptr; 116 117 /// The symbol for the current function. This is recalculated at the beginning 118 /// of each call to runOnMachineFunction(). 119 MCSymbol *CurrentFnSym = nullptr; 120 121 /// The symbol for the current function descriptor on AIX. This is created 122 /// at the beginning of each call to SetupMachineFunction(). 123 MCSymbol *CurrentFnDescSym = nullptr; 124 125 /// The symbol used to represent the start of the current function for the 126 /// purpose of calculating its size (e.g. using the .size directive). By 127 /// default, this is equal to CurrentFnSym. 128 MCSymbol *CurrentFnSymForSize = nullptr; 129 130 /// Map a basic block section ID to the begin and end symbols of that section 131 /// which determine the section's range. 132 struct MBBSectionRange { 133 MCSymbol *BeginLabel, *EndLabel; 134 }; 135 136 MapVector<unsigned, MBBSectionRange> MBBSectionRanges; 137 138 /// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of 139 /// its number of uses by other globals. 140 using GOTEquivUsePair = std::pair<const GlobalVariable *, unsigned>; 141 MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs; 142 143 /// struct HandlerInfo and Handlers permit users or target extended 144 /// AsmPrinter to add their own handlers. 145 struct HandlerInfo { 146 std::unique_ptr<AsmPrinterHandler> Handler; 147 StringRef TimerName; 148 StringRef TimerDescription; 149 StringRef TimerGroupName; 150 StringRef TimerGroupDescription; 151 152 HandlerInfo(std::unique_ptr<AsmPrinterHandler> Handler, StringRef TimerName, 153 StringRef TimerDescription, StringRef TimerGroupName, 154 StringRef TimerGroupDescription) 155 : Handler(std::move(Handler)), TimerName(TimerName), 156 TimerDescription(TimerDescription), TimerGroupName(TimerGroupName), 157 TimerGroupDescription(TimerGroupDescription) {} 158 }; 159 160 // Flags representing which CFI section is required for a function/module. 161 enum class CFISection : unsigned { 162 None = 0, ///< Do not emit either .eh_frame or .debug_frame 163 EH = 1, ///< Emit .eh_frame 164 Debug = 2 ///< Emit .debug_frame 165 }; 166 167 private: 168 MCSymbol *CurrentFnEnd = nullptr; 169 170 /// Map a basic block section ID to the exception symbol associated with that 171 /// section. Map entries are assigned and looked up via 172 /// AsmPrinter::getMBBExceptionSym. 173 DenseMap<unsigned, MCSymbol *> MBBSectionExceptionSyms; 174 175 // The symbol used to represent the start of the current BB section of the 176 // function. This is used to calculate the size of the BB section. 177 MCSymbol *CurrentSectionBeginSym = nullptr; 178 179 // The garbage collection metadata printer table. 180 void *GCMetadataPrinters = nullptr; // Really a DenseMap. 181 182 /// Emit comments in assembly output if this is true. 183 bool VerboseAsm; 184 185 /// Output stream for the stack usage file (i.e., .su file). 186 std::unique_ptr<raw_fd_ostream> StackUsageStream; 187 188 static char ID; 189 190 protected: 191 MCSymbol *CurrentFnBegin = nullptr; 192 193 /// A vector of all debug/EH info emitters we should use. This vector 194 /// maintains ownership of the emitters. 195 std::vector<HandlerInfo> Handlers; 196 size_t NumUserHandlers = 0; 197 198 private: 199 /// If generated on the fly this own the instance. 200 std::unique_ptr<MachineDominatorTree> OwnedMDT; 201 202 /// If generated on the fly this own the instance. 203 std::unique_ptr<MachineLoopInfo> OwnedMLI; 204 205 /// If the target supports dwarf debug info, this pointer is non-null. 206 DwarfDebug *DD = nullptr; 207 208 /// A handler that supports pseudo probe emission with embedded inline 209 /// context. 210 PseudoProbeHandler *PP = nullptr; 211 212 /// CFISection type the module needs i.e. either .eh_frame or .debug_frame. 213 CFISection ModuleCFISection = CFISection::None; 214 215 protected: 216 explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer); 217 218 public: 219 ~AsmPrinter() override; 220 221 DwarfDebug *getDwarfDebug() { return DD; } 222 DwarfDebug *getDwarfDebug() const { return DD; } 223 224 uint16_t getDwarfVersion() const; 225 void setDwarfVersion(uint16_t Version); 226 227 bool isDwarf64() const; 228 229 /// Returns 4 for DWARF32 and 8 for DWARF64. 230 unsigned int getDwarfOffsetByteSize() const; 231 232 /// Returns 4 for DWARF32 and 12 for DWARF64. 233 unsigned int getUnitLengthFieldByteSize() const; 234 235 bool isPositionIndependent() const; 236 237 /// Return true if assembly output should contain comments. 238 bool isVerbose() const { return VerboseAsm; } 239 240 /// Return a unique ID for the current function. 241 unsigned getFunctionNumber() const; 242 243 /// Return symbol for the function pseudo stack if the stack frame is not a 244 /// register based. 245 virtual const MCSymbol *getFunctionFrameSymbol() const { return nullptr; } 246 247 MCSymbol *getFunctionBegin() const { return CurrentFnBegin; } 248 MCSymbol *getFunctionEnd() const { return CurrentFnEnd; } 249 250 // Return the exception symbol associated with the MBB section containing a 251 // given basic block. 252 MCSymbol *getMBBExceptionSym(const MachineBasicBlock &MBB); 253 254 /// Return information about object file lowering. 255 const TargetLoweringObjectFile &getObjFileLowering() const; 256 257 /// Return information about data layout. 258 const DataLayout &getDataLayout() const; 259 260 /// Return the pointer size from the TargetMachine 261 unsigned getPointerSize() const; 262 263 /// Return information about subtarget. 264 const MCSubtargetInfo &getSubtargetInfo() const; 265 266 void EmitToStreamer(MCStreamer &S, const MCInst &Inst); 267 268 /// Emits inital debug location directive. 269 void emitInitialRawDwarfLocDirective(const MachineFunction &MF); 270 271 /// Return the current section we are emitting to. 272 const MCSection *getCurrentSection() const; 273 274 void getNameWithPrefix(SmallVectorImpl<char> &Name, 275 const GlobalValue *GV) const; 276 277 MCSymbol *getSymbol(const GlobalValue *GV) const; 278 279 /// Similar to getSymbol() but preferred for references. On ELF, this uses a 280 /// local symbol if a reference to GV is guaranteed to be resolved to the 281 /// definition in the same module. 282 MCSymbol *getSymbolPreferLocal(const GlobalValue &GV) const; 283 284 //===------------------------------------------------------------------===// 285 // XRay instrumentation implementation. 286 //===------------------------------------------------------------------===// 287 public: 288 // This describes the kind of sled we're storing in the XRay table. 289 enum class SledKind : uint8_t { 290 FUNCTION_ENTER = 0, 291 FUNCTION_EXIT = 1, 292 TAIL_CALL = 2, 293 LOG_ARGS_ENTER = 3, 294 CUSTOM_EVENT = 4, 295 TYPED_EVENT = 5, 296 }; 297 298 // The table will contain these structs that point to the sled, the function 299 // containing the sled, and what kind of sled (and whether they should always 300 // be instrumented). We also use a version identifier that the runtime can use 301 // to decide what to do with the sled, depending on the version of the sled. 302 struct XRayFunctionEntry { 303 const MCSymbol *Sled; 304 const MCSymbol *Function; 305 SledKind Kind; 306 bool AlwaysInstrument; 307 const class Function *Fn; 308 uint8_t Version; 309 310 void emit(int, MCStreamer *) const; 311 }; 312 313 // All the sleds to be emitted. 314 SmallVector<XRayFunctionEntry, 4> Sleds; 315 316 // Helper function to record a given XRay sled. 317 void recordSled(MCSymbol *Sled, const MachineInstr &MI, SledKind Kind, 318 uint8_t Version = 0); 319 320 /// Emit a table with all XRay instrumentation points. 321 void emitXRayTable(); 322 323 void emitPatchableFunctionEntries(); 324 325 //===------------------------------------------------------------------===// 326 // MachineFunctionPass Implementation. 327 //===------------------------------------------------------------------===// 328 329 /// Record analysis usage. 330 void getAnalysisUsage(AnalysisUsage &AU) const override; 331 332 /// Set up the AsmPrinter when we are working on a new module. If your pass 333 /// overrides this, it must make sure to explicitly call this implementation. 334 bool doInitialization(Module &M) override; 335 336 /// Shut down the asmprinter. If you override this in your pass, you must make 337 /// sure to call it explicitly. 338 bool doFinalization(Module &M) override; 339 340 /// Emit the specified function out to the OutStreamer. 341 bool runOnMachineFunction(MachineFunction &MF) override { 342 SetupMachineFunction(MF); 343 emitFunctionBody(); 344 return false; 345 } 346 347 //===------------------------------------------------------------------===// 348 // Coarse grained IR lowering routines. 349 //===------------------------------------------------------------------===// 350 351 /// This should be called when a new MachineFunction is being processed from 352 /// runOnMachineFunction. 353 virtual void SetupMachineFunction(MachineFunction &MF); 354 355 /// This method emits the body and trailer for a function. 356 void emitFunctionBody(); 357 358 void emitCFIInstruction(const MachineInstr &MI); 359 360 void emitFrameAlloc(const MachineInstr &MI); 361 362 void emitStackSizeSection(const MachineFunction &MF); 363 364 void emitStackUsage(const MachineFunction &MF); 365 366 void emitBBAddrMapSection(const MachineFunction &MF); 367 368 void emitPseudoProbe(const MachineInstr &MI); 369 370 void emitRemarksSection(remarks::RemarkStreamer &RS); 371 372 /// Get the CFISection type for a function. 373 CFISection getFunctionCFISectionType(const Function &F) const; 374 375 /// Get the CFISection type for a function. 376 CFISection getFunctionCFISectionType(const MachineFunction &MF) const; 377 378 /// Get the CFISection type for the module. 379 CFISection getModuleCFISectionType() const { return ModuleCFISection; } 380 381 bool needsSEHMoves(); 382 383 /// Since emitting CFI unwind information is entangled with supporting the 384 /// exceptions, this returns true for platforms which use CFI unwind 385 /// information for debugging purpose when 386 /// `MCAsmInfo::ExceptionsType == ExceptionHandling::None`. 387 bool needsCFIForDebug() const; 388 389 /// Print to the current output stream assembly representations of the 390 /// constants in the constant pool MCP. This is used to print out constants 391 /// which have been "spilled to memory" by the code generator. 392 virtual void emitConstantPool(); 393 394 /// Print assembly representations of the jump tables used by the current 395 /// function to the current output stream. 396 virtual void emitJumpTableInfo(); 397 398 /// Emit the specified global variable to the .s file. 399 virtual void emitGlobalVariable(const GlobalVariable *GV); 400 401 /// Check to see if the specified global is a special global used by LLVM. If 402 /// so, emit it and return true, otherwise do nothing and return false. 403 bool emitSpecialLLVMGlobal(const GlobalVariable *GV); 404 405 /// `llvm.global_ctors` and `llvm.global_dtors` are arrays of Structor 406 /// structs. 407 /// 408 /// Priority - init priority 409 /// Func - global initialization or global clean-up function 410 /// ComdatKey - associated data 411 struct Structor { 412 int Priority = 0; 413 Constant *Func = nullptr; 414 GlobalValue *ComdatKey = nullptr; 415 416 Structor() = default; 417 }; 418 419 /// This method gathers an array of Structors and then sorts them out by 420 /// Priority. 421 /// @param List The initializer of `llvm.global_ctors` or `llvm.global_dtors` 422 /// array. 423 /// @param[out] Structors Sorted Structor structs by Priority. 424 void preprocessXXStructorList(const DataLayout &DL, const Constant *List, 425 SmallVector<Structor, 8> &Structors); 426 427 /// This method emits `llvm.global_ctors` or `llvm.global_dtors` list. 428 virtual void emitXXStructorList(const DataLayout &DL, const Constant *List, 429 bool IsCtor); 430 431 /// Emit an alignment directive to the specified power of two boundary. If a 432 /// global value is specified, and if that global has an explicit alignment 433 /// requested, it will override the alignment request if required for 434 /// correctness. 435 void emitAlignment(Align Alignment, const GlobalObject *GV = nullptr) const; 436 437 /// Lower the specified LLVM Constant to an MCExpr. 438 virtual const MCExpr *lowerConstant(const Constant *CV); 439 440 /// Print a general LLVM constant to the .s file. 441 void emitGlobalConstant(const DataLayout &DL, const Constant *CV); 442 443 /// Unnamed constant global variables solely contaning a pointer to 444 /// another globals variable act like a global variable "proxy", or GOT 445 /// equivalents, i.e., it's only used to hold the address of the latter. One 446 /// optimization is to replace accesses to these proxies by using the GOT 447 /// entry for the final global instead. Hence, we select GOT equivalent 448 /// candidates among all the module global variables, avoid emitting them 449 /// unnecessarily and finally replace references to them by pc relative 450 /// accesses to GOT entries. 451 void computeGlobalGOTEquivs(Module &M); 452 453 /// Constant expressions using GOT equivalent globals may not be 454 /// eligible for PC relative GOT entry conversion, in such cases we need to 455 /// emit the proxies we previously omitted in EmitGlobalVariable. 456 void emitGlobalGOTEquivs(); 457 458 /// Emit the stack maps. 459 void emitStackMaps(StackMaps &SM); 460 461 //===------------------------------------------------------------------===// 462 // Overridable Hooks 463 //===------------------------------------------------------------------===// 464 465 void addAsmPrinterHandler(HandlerInfo Handler) { 466 Handlers.insert(Handlers.begin(), std::move(Handler)); 467 NumUserHandlers++; 468 } 469 470 // Targets can, or in the case of EmitInstruction, must implement these to 471 // customize output. 472 473 /// This virtual method can be overridden by targets that want to emit 474 /// something at the start of their file. 475 virtual void emitStartOfAsmFile(Module &) {} 476 477 /// This virtual method can be overridden by targets that want to emit 478 /// something at the end of their file. 479 virtual void emitEndOfAsmFile(Module &) {} 480 481 /// Targets can override this to emit stuff before the first basic block in 482 /// the function. 483 virtual void emitFunctionBodyStart() {} 484 485 /// Targets can override this to emit stuff after the last basic block in the 486 /// function. 487 virtual void emitFunctionBodyEnd() {} 488 489 /// Targets can override this to emit stuff at the start of a basic block. 490 /// By default, this method prints the label for the specified 491 /// MachineBasicBlock, an alignment (if present) and a comment describing it 492 /// if appropriate. 493 virtual void emitBasicBlockStart(const MachineBasicBlock &MBB); 494 495 /// Targets can override this to emit stuff at the end of a basic block. 496 virtual void emitBasicBlockEnd(const MachineBasicBlock &MBB); 497 498 /// Targets should implement this to emit instructions. 499 virtual void emitInstruction(const MachineInstr *) { 500 llvm_unreachable("EmitInstruction not implemented"); 501 } 502 503 /// Return the symbol for the specified constant pool entry. 504 virtual MCSymbol *GetCPISymbol(unsigned CPID) const; 505 506 virtual void emitFunctionEntryLabel(); 507 508 virtual void emitFunctionDescriptor() { 509 llvm_unreachable("Function descriptor is target-specific."); 510 } 511 512 virtual void emitMachineConstantPoolValue(MachineConstantPoolValue *MCPV); 513 514 /// Targets can override this to change how global constants that are part of 515 /// a C++ static/global constructor list are emitted. 516 virtual void emitXXStructor(const DataLayout &DL, const Constant *CV) { 517 emitGlobalConstant(DL, CV); 518 } 519 520 /// Return true if the basic block has exactly one predecessor and the control 521 /// transfer mechanism between the predecessor and this block is a 522 /// fall-through. 523 virtual bool 524 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const; 525 526 /// Targets can override this to customize the output of IMPLICIT_DEF 527 /// instructions in verbose mode. 528 virtual void emitImplicitDef(const MachineInstr *MI) const; 529 530 /// Emit N NOP instructions. 531 void emitNops(unsigned N); 532 533 //===------------------------------------------------------------------===// 534 // Symbol Lowering Routines. 535 //===------------------------------------------------------------------===// 536 537 MCSymbol *createTempSymbol(const Twine &Name) const; 538 539 /// Return the MCSymbol for a private symbol with global value name as its 540 /// base, with the specified suffix. 541 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV, 542 StringRef Suffix) const; 543 544 /// Return the MCSymbol for the specified ExternalSymbol. 545 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const; 546 547 /// Return the symbol for the specified jump table entry. 548 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const; 549 550 /// Return the symbol for the specified jump table .set 551 /// FIXME: privatize to AsmPrinter. 552 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const; 553 554 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified 555 /// basic block. 556 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const; 557 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const; 558 559 //===------------------------------------------------------------------===// 560 // Emission Helper Routines. 561 //===------------------------------------------------------------------===// 562 563 /// This is just convenient handler for printing offsets. 564 void printOffset(int64_t Offset, raw_ostream &OS) const; 565 566 /// Emit a byte directive and value. 567 void emitInt8(int Value) const; 568 569 /// Emit a short directive and value. 570 void emitInt16(int Value) const; 571 572 /// Emit a long directive and value. 573 void emitInt32(int Value) const; 574 575 /// Emit a long long directive and value. 576 void emitInt64(uint64_t Value) const; 577 578 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive 579 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses 580 /// .set if it is available. 581 void emitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo, 582 unsigned Size) const; 583 584 /// Emit something like ".uleb128 Hi-Lo". 585 void emitLabelDifferenceAsULEB128(const MCSymbol *Hi, 586 const MCSymbol *Lo) const; 587 588 /// Emit something like ".long Label+Offset" where the size in bytes of the 589 /// directive is specified by Size and Label specifies the label. This 590 /// implicitly uses .set if it is available. 591 void emitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset, 592 unsigned Size, bool IsSectionRelative = false) const; 593 594 /// Emit something like ".long Label" where the size in bytes of the directive 595 /// is specified by Size and Label specifies the label. 596 void emitLabelReference(const MCSymbol *Label, unsigned Size, 597 bool IsSectionRelative = false) const { 598 emitLabelPlusOffset(Label, 0, Size, IsSectionRelative); 599 } 600 601 //===------------------------------------------------------------------===// 602 // Dwarf Emission Helper Routines 603 //===------------------------------------------------------------------===// 604 605 /// Emit the specified signed leb128 value. 606 void emitSLEB128(int64_t Value, const char *Desc = nullptr) const; 607 608 /// Emit the specified unsigned leb128 value. 609 void emitULEB128(uint64_t Value, const char *Desc = nullptr, 610 unsigned PadTo = 0) const; 611 612 /// Emit a .byte 42 directive that corresponds to an encoding. If verbose 613 /// assembly output is enabled, we output comments describing the encoding. 614 /// Desc is a string saying what the encoding is specifying (e.g. "LSDA"). 615 void emitEncodingByte(unsigned Val, const char *Desc = nullptr) const; 616 617 /// Return the size of the encoding in bytes. 618 unsigned GetSizeOfEncodedValue(unsigned Encoding) const; 619 620 /// Emit reference to a ttype global with a specified encoding. 621 virtual void emitTTypeReference(const GlobalValue *GV, unsigned Encoding); 622 623 /// Emit a reference to a symbol for use in dwarf. Different object formats 624 /// represent this in different ways. Some use a relocation others encode 625 /// the label offset in its section. 626 void emitDwarfSymbolReference(const MCSymbol *Label, 627 bool ForceOffset = false) const; 628 629 /// Emit the 4- or 8-byte offset of a string from the start of its section. 630 /// 631 /// When possible, emit a DwarfStringPool section offset without any 632 /// relocations, and without using the symbol. Otherwise, defers to \a 633 /// emitDwarfSymbolReference(). 634 /// 635 /// The length of the emitted value depends on the DWARF format. 636 void emitDwarfStringOffset(DwarfStringPoolEntry S) const; 637 638 /// Emit the 4-or 8-byte offset of a string from the start of its section. 639 void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const { 640 emitDwarfStringOffset(S.getEntry()); 641 } 642 643 /// Emit something like ".long Label + Offset" or ".quad Label + Offset" 644 /// depending on the DWARF format. 645 void emitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const; 646 647 /// Emit 32- or 64-bit value depending on the DWARF format. 648 void emitDwarfLengthOrOffset(uint64_t Value) const; 649 650 /// Emit a unit length field. The actual format, DWARF32 or DWARF64, is chosen 651 /// according to the settings. 652 void emitDwarfUnitLength(uint64_t Length, const Twine &Comment) const; 653 654 /// Emit a unit length field. The actual format, DWARF32 or DWARF64, is chosen 655 /// according to the settings. 656 /// Return the end symbol generated inside, the caller needs to emit it. 657 MCSymbol *emitDwarfUnitLength(const Twine &Prefix, 658 const Twine &Comment) const; 659 660 /// Emit reference to a call site with a specified encoding 661 void emitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo, 662 unsigned Encoding) const; 663 /// Emit an integer value corresponding to the call site encoding 664 void emitCallSiteValue(uint64_t Value, unsigned Encoding) const; 665 666 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified. 667 virtual unsigned getISAEncoding() { return 0; } 668 669 /// Emit the directive and value for debug thread local expression 670 /// 671 /// \p Value - The value to emit. 672 /// \p Size - The size of the integer (in bytes) to emit. 673 virtual void emitDebugValue(const MCExpr *Value, unsigned Size) const; 674 675 //===------------------------------------------------------------------===// 676 // Dwarf Lowering Routines 677 //===------------------------------------------------------------------===// 678 679 /// Emit frame instruction to describe the layout of the frame. 680 void emitCFIInstruction(const MCCFIInstruction &Inst) const; 681 682 /// Emit Dwarf abbreviation table. 683 template <typename T> void emitDwarfAbbrevs(const T &Abbrevs) const { 684 // For each abbreviation. 685 for (const auto &Abbrev : Abbrevs) 686 emitDwarfAbbrev(*Abbrev); 687 688 // Mark end of abbreviations. 689 emitULEB128(0, "EOM(3)"); 690 } 691 692 void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const; 693 694 /// Recursively emit Dwarf DIE tree. 695 void emitDwarfDIE(const DIE &Die) const; 696 697 //===------------------------------------------------------------------===// 698 // Inline Asm Support 699 //===------------------------------------------------------------------===// 700 701 // These are hooks that targets can override to implement inline asm 702 // support. These should probably be moved out of AsmPrinter someday. 703 704 /// Print information related to the specified machine instr that is 705 /// independent of the operand, and may be independent of the instr itself. 706 /// This can be useful for portably encoding the comment character or other 707 /// bits of target-specific knowledge into the asmstrings. The syntax used is 708 /// ${:comment}. Targets can override this to add support for their own 709 /// strange codes. 710 virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS, 711 const char *Code) const; 712 713 /// Print the MachineOperand as a symbol. Targets with complex handling of 714 /// symbol references should override the base implementation. 715 virtual void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &OS); 716 717 /// Print the specified operand of MI, an INLINEASM instruction, using the 718 /// specified assembler variant. Targets should override this to format as 719 /// appropriate. This method can return true if the operand is erroneous. 720 virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo, 721 const char *ExtraCode, raw_ostream &OS); 722 723 /// Print the specified operand of MI, an INLINEASM instruction, using the 724 /// specified assembler variant as an address. Targets should override this to 725 /// format as appropriate. This method can return true if the operand is 726 /// erroneous. 727 virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo, 728 const char *ExtraCode, raw_ostream &OS); 729 730 /// Let the target do anything it needs to do before emitting inlineasm. 731 /// \p StartInfo - the subtarget info before parsing inline asm 732 virtual void emitInlineAsmStart() const; 733 734 /// Let the target do anything it needs to do after emitting inlineasm. 735 /// This callback can be used restore the original mode in case the 736 /// inlineasm contains directives to switch modes. 737 /// \p StartInfo - the original subtarget info before inline asm 738 /// \p EndInfo - the final subtarget info after parsing the inline asm, 739 /// or NULL if the value is unknown. 740 virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo, 741 const MCSubtargetInfo *EndInfo) const; 742 743 /// This emits visibility information about symbol, if this is supported by 744 /// the target. 745 void emitVisibility(MCSymbol *Sym, unsigned Visibility, 746 bool IsDefinition = true) const; 747 748 /// This emits linkage information about \p GVSym based on \p GV, if this is 749 /// supported by the target. 750 virtual void emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const; 751 752 /// Return the alignment for the specified \p GV. 753 static Align getGVAlignment(const GlobalObject *GV, const DataLayout &DL, 754 Align InAlign = Align(1)); 755 756 private: 757 /// Private state for PrintSpecial() 758 // Assign a unique ID to this machine instruction. 759 mutable const MachineInstr *LastMI = nullptr; 760 mutable unsigned LastFn = 0; 761 mutable unsigned Counter = ~0U; 762 763 /// This method emits the header for the current function. 764 virtual void emitFunctionHeader(); 765 766 /// This method emits a comment next to header for the current function. 767 virtual void emitFunctionHeaderComment(); 768 769 /// Emit a blob of inline asm to the output streamer. 770 void 771 emitInlineAsm(StringRef Str, const MCSubtargetInfo &STI, 772 const MCTargetOptions &MCOptions, 773 const MDNode *LocMDNode = nullptr, 774 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const; 775 776 /// This method formats and emits the specified machine instruction that is an 777 /// inline asm. 778 void emitInlineAsm(const MachineInstr *MI) const; 779 780 /// Add inline assembly info to the diagnostics machinery, so we can 781 /// emit file and position info. Returns SrcMgr memory buffer position. 782 unsigned addInlineAsmDiagBuffer(StringRef AsmStr, 783 const MDNode *LocMDNode) const; 784 785 //===------------------------------------------------------------------===// 786 // Internal Implementation Details 787 //===------------------------------------------------------------------===// 788 789 void emitJumpTableEntry(const MachineJumpTableInfo *MJTI, 790 const MachineBasicBlock *MBB, unsigned uid) const; 791 void emitLLVMUsedList(const ConstantArray *InitList); 792 /// Emit llvm.ident metadata in an '.ident' directive. 793 void emitModuleIdents(Module &M); 794 /// Emit bytes for llvm.commandline metadata. 795 void emitModuleCommandLines(Module &M); 796 797 GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &S); 798 /// Emit GlobalAlias or GlobalIFunc. 799 void emitGlobalIndirectSymbol(Module &M, const GlobalIndirectSymbol &GIS); 800 801 /// This method decides whether the specified basic block requires a label. 802 bool shouldEmitLabelForBasicBlock(const MachineBasicBlock &MBB) const; 803 }; 804 805 } // end namespace llvm 806 807 #endif // LLVM_CODEGEN_ASMPRINTER_H 808