1 //===-- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework --------*- 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 contains a class to be used as the base class for target specific 11 // asm writers. This class primarily handles common functionality used by 12 // all asm writers. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #ifndef LLVM_CODEGEN_ASMPRINTER_H 17 #define LLVM_CODEGEN_ASMPRINTER_H 18 19 #include "llvm/ADT/Twine.h" 20 #include "llvm/CodeGen/MachineFunctionPass.h" 21 #include "llvm/IR/InlineAsm.h" 22 #include "llvm/Support/DataTypes.h" 23 #include "llvm/Support/ErrorHandling.h" 24 25 namespace llvm { 26 class AsmPrinterHandler; 27 class BlockAddress; 28 class ByteStreamer; 29 class GCStrategy; 30 class Constant; 31 class ConstantArray; 32 class GCMetadataPrinter; 33 class GlobalValue; 34 class GlobalVariable; 35 class MachineBasicBlock; 36 class MachineFunction; 37 class MachineInstr; 38 class MachineLocation; 39 class MachineLoopInfo; 40 class MachineLoop; 41 class MachineConstantPoolValue; 42 class MachineJumpTableInfo; 43 class MachineModuleInfo; 44 class MCAsmInfo; 45 class MCCFIInstruction; 46 class MCContext; 47 class MCExpr; 48 class MCInst; 49 class MCInstrInfo; 50 class MCSection; 51 class MCStreamer; 52 class MCSubtargetInfo; 53 class MCSymbol; 54 class MDNode; 55 class DwarfDebug; 56 class Mangler; 57 class TargetLoweringObjectFile; 58 class DataLayout; 59 class TargetMachine; 60 61 /// This class is intended to be used as a driving class for all asm writers. 62 class AsmPrinter : public MachineFunctionPass { 63 public: 64 /// Target machine description. 65 /// 66 TargetMachine &TM; 67 68 /// Target Asm Printer information. 69 /// 70 const MCAsmInfo *MAI; 71 72 const MCInstrInfo *MII; 73 /// This is the context for the output file that we are streaming. This owns 74 /// all of the global MC-related objects for the generated translation unit. 75 MCContext &OutContext; 76 77 /// This is the MCStreamer object for the file we are generating. This 78 /// contains the transient state for the current translation unit that we are 79 /// generating (such as the current section etc). 80 MCStreamer &OutStreamer; 81 82 /// The current machine function. 83 const MachineFunction *MF; 84 85 /// This is a pointer to the current MachineModuleInfo. 86 MachineModuleInfo *MMI; 87 88 /// Name-mangler for global names. 89 /// 90 Mangler *Mang; 91 92 /// The symbol for the current function. This is recalculated at the beginning 93 /// of each call to runOnMachineFunction(). 94 /// 95 MCSymbol *CurrentFnSym; 96 97 /// The symbol used to represent the start of the current function for the 98 /// purpose of calculating its size (e.g. using the .size directive). By 99 /// default, this is equal to CurrentFnSym. 100 MCSymbol *CurrentFnSymForSize; 101 102 private: 103 // The garbage collection metadata printer table. 104 void *GCMetadataPrinters; // Really a DenseMap. 105 106 /// Emit comments in assembly output if this is true. 107 /// 108 bool VerboseAsm; 109 static char ID; 110 111 /// If VerboseAsm is set, a pointer to the loop info for this function. 112 MachineLoopInfo *LI; 113 114 struct HandlerInfo { 115 AsmPrinterHandler *Handler; 116 const char *TimerName, *TimerGroupName; HandlerInfoHandlerInfo117 HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName, 118 const char *TimerGroupName) 119 : Handler(Handler), TimerName(TimerName), 120 TimerGroupName(TimerGroupName) {} 121 }; 122 /// A vector of all debug/EH info emitters we should use. This vector 123 /// maintains ownership of the emitters. 124 SmallVector<HandlerInfo, 1> Handlers; 125 126 /// If the target supports dwarf debug info, this pointer is non-null. 127 DwarfDebug *DD; 128 129 protected: 130 explicit AsmPrinter(TargetMachine &TM, MCStreamer &Streamer); 131 132 public: 133 virtual ~AsmPrinter(); 134 getDwarfDebug()135 DwarfDebug *getDwarfDebug() { return DD; } getDwarfDebug()136 DwarfDebug *getDwarfDebug() const { return DD; } 137 138 /// Return true if assembly output should contain comments. 139 /// isVerbose()140 bool isVerbose() const { return VerboseAsm; } 141 142 /// Return a unique ID for the current function. 143 /// 144 unsigned getFunctionNumber() const; 145 146 /// Return information about object file lowering. 147 const TargetLoweringObjectFile &getObjFileLowering() const; 148 149 /// Return information about data layout. 150 const DataLayout &getDataLayout() const; 151 152 /// Return information about subtarget. 153 const MCSubtargetInfo &getSubtargetInfo() const; 154 155 void EmitToStreamer(MCStreamer &S, const MCInst &Inst); 156 157 /// Return the target triple string. 158 StringRef getTargetTriple() const; 159 160 /// Return the current section we are emitting to. 161 const MCSection *getCurrentSection() const; 162 163 void getNameWithPrefix(SmallVectorImpl<char> &Name, 164 const GlobalValue *GV) const; 165 166 MCSymbol *getSymbol(const GlobalValue *GV) const; 167 168 //===------------------------------------------------------------------===// 169 // MachineFunctionPass Implementation. 170 //===------------------------------------------------------------------===// 171 172 /// Record analysis usage. 173 /// 174 void getAnalysisUsage(AnalysisUsage &AU) const override; 175 176 /// Set up the AsmPrinter when we are working on a new module. If your pass 177 /// overrides this, it must make sure to explicitly call this implementation. 178 bool doInitialization(Module &M) override; 179 180 /// Shut down the asmprinter. If you override this in your pass, you must make 181 /// sure to call it explicitly. 182 bool doFinalization(Module &M) override; 183 184 /// Emit the specified function out to the OutStreamer. runOnMachineFunction(MachineFunction & MF)185 bool runOnMachineFunction(MachineFunction &MF) override { 186 SetupMachineFunction(MF); 187 EmitFunctionHeader(); 188 EmitFunctionBody(); 189 return false; 190 } 191 192 //===------------------------------------------------------------------===// 193 // Coarse grained IR lowering routines. 194 //===------------------------------------------------------------------===// 195 196 /// This should be called when a new MachineFunction is being processed from 197 /// runOnMachineFunction. 198 void SetupMachineFunction(MachineFunction &MF); 199 200 /// This method emits the header for the current function. 201 void EmitFunctionHeader(); 202 203 /// This method emits the body and trailer for a function. 204 void EmitFunctionBody(); 205 206 void emitCFIInstruction(const MachineInstr &MI); 207 208 void emitFrameAlloc(const MachineInstr &MI); 209 210 enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug }; 211 CFIMoveType needsCFIMoves(); 212 213 bool needsSEHMoves(); 214 215 /// Print to the current output stream assembly representations of the 216 /// constants in the constant pool MCP. This is used to print out constants 217 /// which have been "spilled to memory" by the code generator. 218 /// 219 virtual void EmitConstantPool(); 220 221 /// Print assembly representations of the jump tables used by the current 222 /// function to the current output stream. 223 /// 224 void EmitJumpTableInfo(); 225 226 /// Emit the specified global variable to the .s file. 227 virtual void EmitGlobalVariable(const GlobalVariable *GV); 228 229 /// Check to see if the specified global is a special global used by LLVM. If 230 /// so, emit it and return true, otherwise do nothing and return false. 231 bool EmitSpecialLLVMGlobal(const GlobalVariable *GV); 232 233 /// Emit an alignment directive to the specified power of two boundary. For 234 /// example, if you pass in 3 here, you will get an 8 byte alignment. If a 235 /// global value is specified, and if that global has an explicit alignment 236 /// requested, it will override the alignment request if required for 237 /// correctness. 238 /// 239 void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const; 240 241 /// This method prints the label for the specified MachineBasicBlock, an 242 /// alignment (if present) and a comment describing it if appropriate. 243 void EmitBasicBlockStart(const MachineBasicBlock &MBB) const; 244 245 /// Lower the specified LLVM Constant to an MCExpr. 246 const MCExpr *lowerConstant(const Constant *CV); 247 248 /// \brief Print a general LLVM constant to the .s file. 249 void EmitGlobalConstant(const Constant *CV); 250 251 //===------------------------------------------------------------------===// 252 // Overridable Hooks 253 //===------------------------------------------------------------------===// 254 255 // Targets can, or in the case of EmitInstruction, must implement these to 256 // customize output. 257 258 /// This virtual method can be overridden by targets that want to emit 259 /// something at the start of their file. EmitStartOfAsmFile(Module &)260 virtual void EmitStartOfAsmFile(Module &) {} 261 262 /// This virtual method can be overridden by targets that want to emit 263 /// something at the end of their file. EmitEndOfAsmFile(Module &)264 virtual void EmitEndOfAsmFile(Module &) {} 265 266 /// Targets can override this to emit stuff before the first basic block in 267 /// the function. EmitFunctionBodyStart()268 virtual void EmitFunctionBodyStart() {} 269 270 /// Targets can override this to emit stuff after the last basic block in the 271 /// function. EmitFunctionBodyEnd()272 virtual void EmitFunctionBodyEnd() {} 273 274 /// Targets can override this to emit stuff at the end of a basic block. EmitBasicBlockEnd(const MachineBasicBlock & MBB)275 virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB) {} 276 277 /// Targets should implement this to emit instructions. EmitInstruction(const MachineInstr *)278 virtual void EmitInstruction(const MachineInstr *) { 279 llvm_unreachable("EmitInstruction not implemented"); 280 } 281 282 /// Return the symbol for the specified constant pool entry. 283 virtual MCSymbol *GetCPISymbol(unsigned CPID) const; 284 285 virtual void EmitFunctionEntryLabel(); 286 287 virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV); 288 289 /// Targets can override this to change how global constants that are part of 290 /// a C++ static/global constructor list are emitted. EmitXXStructor(const Constant * CV)291 virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); } 292 293 /// Return true if the basic block has exactly one predecessor and the control 294 /// transfer mechanism between the predecessor and this block is a 295 /// fall-through. 296 virtual bool 297 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const; 298 299 /// Targets can override this to customize the output of IMPLICIT_DEF 300 /// instructions in verbose mode. 301 virtual void emitImplicitDef(const MachineInstr *MI) const; 302 303 //===------------------------------------------------------------------===// 304 // Symbol Lowering Routines. 305 //===------------------------------------------------------------------===// 306 public: 307 /// Return the MCSymbol corresponding to the assembler temporary label with 308 /// the specified stem and unique ID. 309 MCSymbol *GetTempSymbol(Twine Name, unsigned ID) const; 310 311 /// Return an assembler temporary label with the specified stem. 312 MCSymbol *GetTempSymbol(Twine Name) const; 313 314 /// Return the MCSymbol for a private symbol with global value name as its 315 /// base, with the specified suffix. 316 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV, 317 StringRef Suffix) const; 318 319 /// Return the MCSymbol for the specified ExternalSymbol. 320 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const; 321 322 /// Return the symbol for the specified jump table entry. 323 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const; 324 325 /// Return the symbol for the specified jump table .set 326 /// FIXME: privatize to AsmPrinter. 327 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const; 328 329 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified 330 /// basic block. 331 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const; 332 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const; 333 334 //===------------------------------------------------------------------===// 335 // Emission Helper Routines. 336 //===------------------------------------------------------------------===// 337 public: 338 /// This is just convenient handler for printing offsets. 339 void printOffset(int64_t Offset, raw_ostream &OS) const; 340 341 /// Emit a byte directive and value. 342 /// 343 void EmitInt8(int Value) const; 344 345 /// Emit a short directive and value. 346 /// 347 void EmitInt16(int Value) const; 348 349 /// Emit a long directive and value. 350 /// 351 void EmitInt32(int Value) const; 352 353 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive 354 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses 355 /// .set if it is available. 356 void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo, 357 unsigned Size) const; 358 359 /// Emit something like ".long Label+Offset" where the size in bytes of the 360 /// directive is specified by Size and Label specifies the label. This 361 /// implicitly uses .set if it is available. 362 void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset, 363 unsigned Size, bool IsSectionRelative = false) const; 364 365 /// Emit something like ".long Label" where the size in bytes of the directive 366 /// is specified by Size and Label specifies the label. 367 void EmitLabelReference(const MCSymbol *Label, unsigned Size, 368 bool IsSectionRelative = false) const { 369 EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative); 370 } 371 372 //===------------------------------------------------------------------===// 373 // Dwarf Emission Helper Routines 374 //===------------------------------------------------------------------===// 375 376 /// Emit the specified signed leb128 value. 377 void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const; 378 379 /// Emit the specified unsigned leb128 value. 380 void EmitULEB128(uint64_t Value, const char *Desc = nullptr, 381 unsigned PadTo = 0) const; 382 383 /// Emit a .byte 42 directive for a DW_CFA_xxx value. 384 void EmitCFAByte(unsigned Val) const; 385 386 /// Emit a .byte 42 directive that corresponds to an encoding. If verbose 387 /// assembly output is enabled, we output comments describing the encoding. 388 /// Desc is a string saying what the encoding is specifying (e.g. "LSDA"). 389 void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const; 390 391 /// Return the size of the encoding in bytes. 392 unsigned GetSizeOfEncodedValue(unsigned Encoding) const; 393 394 /// Emit reference to a ttype global with a specified encoding. 395 void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const; 396 397 /// Emit the 4-byte offset of Label from the start of its section. This can 398 /// be done with a special directive if the target supports it (e.g. cygwin) 399 /// or by emitting it as an offset from a label at the start of the section. 400 /// 401 /// SectionLabel is a temporary label emitted at the start of the section 402 /// that Label lives in. 403 void EmitSectionOffset(const MCSymbol *Label, 404 const MCSymbol *SectionLabel) const; 405 406 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified. getISAEncoding()407 virtual unsigned getISAEncoding() { return 0; } 408 409 /// Emit a dwarf register operation for describing 410 /// - a small value occupying only part of a register or 411 /// - a register representing only part of a value. 412 void EmitDwarfOpPiece(ByteStreamer &Streamer, unsigned SizeInBits, 413 unsigned OffsetInBits = 0) const; 414 415 416 /// \brief Emit a partial DWARF register operation. 417 /// \param MLoc the register 418 /// \param PieceSize size and 419 /// \param PieceOffset offset of the piece in bits, if this is one 420 /// piece of an aggregate value. 421 /// 422 /// If size and offset is zero an operation for the entire 423 /// register is emitted: Some targets do not provide a DWARF 424 /// register number for every register. If this is the case, this 425 /// function will attempt to emit a DWARF register by emitting a 426 /// piece of a super-register or by piecing together multiple 427 /// subregisters that alias the register. 428 void EmitDwarfRegOpPiece(ByteStreamer &BS, const MachineLocation &MLoc, 429 unsigned PieceSize = 0, 430 unsigned PieceOffset = 0) const; 431 432 /// EmitDwarfRegOp - Emit a dwarf register operation. 433 /// \param Indirect whether this is a register-indirect address 434 virtual void EmitDwarfRegOp(ByteStreamer &BS, const MachineLocation &MLoc, 435 bool Indirect) const; 436 437 //===------------------------------------------------------------------===// 438 // Dwarf Lowering Routines 439 //===------------------------------------------------------------------===// 440 441 /// \brief Emit frame instruction to describe the layout of the frame. 442 void emitCFIInstruction(const MCCFIInstruction &Inst) const; 443 444 //===------------------------------------------------------------------===// 445 // Inline Asm Support 446 //===------------------------------------------------------------------===// 447 public: 448 // These are hooks that targets can override to implement inline asm 449 // support. These should probably be moved out of AsmPrinter someday. 450 451 /// Print information related to the specified machine instr that is 452 /// independent of the operand, and may be independent of the instr itself. 453 /// This can be useful for portably encoding the comment character or other 454 /// bits of target-specific knowledge into the asmstrings. The syntax used is 455 /// ${:comment}. Targets can override this to add support for their own 456 /// strange codes. 457 virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS, 458 const char *Code) const; 459 460 /// Print the specified operand of MI, an INLINEASM instruction, using the 461 /// specified assembler variant. Targets should override this to format as 462 /// appropriate. This method can return true if the operand is erroneous. 463 virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo, 464 unsigned AsmVariant, const char *ExtraCode, 465 raw_ostream &OS); 466 467 /// Print the specified operand of MI, an INLINEASM instruction, using the 468 /// specified assembler variant as an address. Targets should override this to 469 /// format as appropriate. This method can return true if the operand is 470 /// erroneous. 471 virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo, 472 unsigned AsmVariant, const char *ExtraCode, 473 raw_ostream &OS); 474 475 /// Let the target do anything it needs to do before emitting inlineasm. 476 /// \p StartInfo - the subtarget info before parsing inline asm 477 virtual void emitInlineAsmStart(const MCSubtargetInfo &StartInfo) const; 478 479 /// Let the target do anything it needs to do after emitting inlineasm. 480 /// This callback can be used restore the original mode in case the 481 /// inlineasm contains directives to switch modes. 482 /// \p StartInfo - the original subtarget info before inline asm 483 /// \p EndInfo - the final subtarget info after parsing the inline asm, 484 /// or NULL if the value is unknown. 485 virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo, 486 const MCSubtargetInfo *EndInfo) const; 487 488 private: 489 /// Private state for PrintSpecial() 490 // Assign a unique ID to this machine instruction. 491 mutable const MachineInstr *LastMI; 492 mutable unsigned LastFn; 493 mutable unsigned Counter; 494 mutable unsigned SetCounter; 495 496 /// Emit a blob of inline asm to the output streamer. 497 void 498 EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = nullptr, 499 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const; 500 501 /// This method formats and emits the specified machine instruction that is an 502 /// inline asm. 503 void EmitInlineAsm(const MachineInstr *MI) const; 504 505 //===------------------------------------------------------------------===// 506 // Internal Implementation Details 507 //===------------------------------------------------------------------===// 508 509 /// This emits visibility information about symbol, if this is suported by the 510 /// target. 511 void EmitVisibility(MCSymbol *Sym, unsigned Visibility, 512 bool IsDefinition = true) const; 513 514 void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const; 515 516 void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI, 517 const MachineBasicBlock *MBB, unsigned uid) const; 518 void EmitLLVMUsedList(const ConstantArray *InitList); 519 /// Emit llvm.ident metadata in an '.ident' directive. 520 void EmitModuleIdents(Module &M); 521 void EmitXXStructorList(const Constant *List, bool isCtor); 522 GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C); 523 }; 524 } 525 526 #endif 527