1 //===-- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CODEGEN_ASMPRINTER_H
17 #define LLVM_CODEGEN_ASMPRINTER_H
19 #include "llvm/ADT/MapVector.h"
20 #include "llvm/ADT/Twine.h"
21 #include "llvm/CodeGen/MachineFunctionPass.h"
22 #include "llvm/IR/InlineAsm.h"
23 #include "llvm/Support/DataTypes.h"
24 #include "llvm/Support/ErrorHandling.h"
27 class AsmPrinterHandler;
35 class GCMetadataPrinter;
38 class MachineBasicBlock;
39 class MachineFunction;
41 class MachineLocation;
42 class MachineLoopInfo;
44 class MachineConstantPoolValue;
45 class MachineJumpTableInfo;
46 class MachineModuleInfo;
48 class MCCFIInstruction;
54 class MCSubtargetInfo;
59 class TargetLoweringObjectFile;
63 /// This class is intended to be used as a driving class for all asm writers.
64 class AsmPrinter : public MachineFunctionPass {
66 /// Target machine description.
70 /// Target Asm Printer information.
74 /// This is the context for the output file that we are streaming. This owns
75 /// all of the global MC-related objects for the generated translation unit.
76 MCContext &OutContext;
78 /// This is the MCStreamer object for the file we are generating. This
79 /// contains the transient state for the current translation unit that we are
80 /// generating (such as the current section etc).
81 MCStreamer &OutStreamer;
83 /// The current machine function.
84 const MachineFunction *MF;
86 /// This is a pointer to the current MachineModuleInfo.
87 MachineModuleInfo *MMI;
89 /// Name-mangler for global names.
93 /// The symbol for the current function. This is recalculated at the beginning
94 /// of each call to runOnMachineFunction().
96 MCSymbol *CurrentFnSym;
98 /// The symbol used to represent the start of the current function for the
99 /// purpose of calculating its size (e.g. using the .size directive). By
100 /// default, this is equal to CurrentFnSym.
101 MCSymbol *CurrentFnSymForSize;
103 /// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of
104 /// its number of uses by other globals.
105 typedef std::pair<const GlobalVariable *, unsigned> GOTEquivUsePair;
106 MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs;
109 MCSymbol *CurrentFnBegin;
110 MCSymbol *CurrentFnEnd;
111 MCSymbol *CurExceptionSym;
113 // The garbage collection metadata printer table.
114 void *GCMetadataPrinters; // Really a DenseMap.
116 /// Emit comments in assembly output if this is true.
121 /// If VerboseAsm is set, a pointer to the loop info for this function.
125 AsmPrinterHandler *Handler;
126 const char *TimerName, *TimerGroupName;
127 HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName,
128 const char *TimerGroupName)
129 : Handler(Handler), TimerName(TimerName),
130 TimerGroupName(TimerGroupName) {}
132 /// A vector of all debug/EH info emitters we should use. This vector
133 /// maintains ownership of the emitters.
134 SmallVector<HandlerInfo, 1> Handlers;
136 /// If the target supports dwarf debug info, this pointer is non-null.
140 explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
143 virtual ~AsmPrinter();
145 DwarfDebug *getDwarfDebug() { return DD; }
146 DwarfDebug *getDwarfDebug() const { return DD; }
148 /// Return true if assembly output should contain comments.
150 bool isVerbose() const { return VerboseAsm; }
152 /// Return a unique ID for the current function.
154 unsigned getFunctionNumber() const;
156 MCSymbol *getFunctionBegin() const { return CurrentFnBegin; }
157 MCSymbol *getFunctionEnd() const { return CurrentFnEnd; }
158 MCSymbol *getCurExceptionSym();
160 /// Return information about object file lowering.
161 const TargetLoweringObjectFile &getObjFileLowering() const;
163 /// Return information about data layout.
164 const DataLayout &getDataLayout() const;
166 /// Return information about subtarget.
167 const MCSubtargetInfo &getSubtargetInfo() const;
169 void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
171 /// Return the target triple string.
172 StringRef getTargetTriple() const;
174 /// Return the current section we are emitting to.
175 const MCSection *getCurrentSection() const;
177 void getNameWithPrefix(SmallVectorImpl<char> &Name,
178 const GlobalValue *GV) const;
180 MCSymbol *getSymbol(const GlobalValue *GV) const;
182 //===------------------------------------------------------------------===//
183 // MachineFunctionPass Implementation.
184 //===------------------------------------------------------------------===//
186 /// Record analysis usage.
188 void getAnalysisUsage(AnalysisUsage &AU) const override;
190 /// Set up the AsmPrinter when we are working on a new module. If your pass
191 /// overrides this, it must make sure to explicitly call this implementation.
192 bool doInitialization(Module &M) override;
194 /// Shut down the asmprinter. If you override this in your pass, you must make
195 /// sure to call it explicitly.
196 bool doFinalization(Module &M) override;
198 /// Emit the specified function out to the OutStreamer.
199 bool runOnMachineFunction(MachineFunction &MF) override {
200 SetupMachineFunction(MF);
205 //===------------------------------------------------------------------===//
206 // Coarse grained IR lowering routines.
207 //===------------------------------------------------------------------===//
209 /// This should be called when a new MachineFunction is being processed from
210 /// runOnMachineFunction.
211 void SetupMachineFunction(MachineFunction &MF);
213 /// This method emits the body and trailer for a function.
214 void EmitFunctionBody();
216 void emitCFIInstruction(const MachineInstr &MI);
218 void emitFrameAlloc(const MachineInstr &MI);
220 enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
221 CFIMoveType needsCFIMoves();
223 bool needsSEHMoves();
225 /// Print to the current output stream assembly representations of the
226 /// constants in the constant pool MCP. This is used to print out constants
227 /// which have been "spilled to memory" by the code generator.
229 virtual void EmitConstantPool();
231 /// Print assembly representations of the jump tables used by the current
232 /// function to the current output stream.
234 void EmitJumpTableInfo();
236 /// Emit the specified global variable to the .s file.
237 virtual void EmitGlobalVariable(const GlobalVariable *GV);
239 /// Check to see if the specified global is a special global used by LLVM. If
240 /// so, emit it and return true, otherwise do nothing and return false.
241 bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
243 /// Emit an alignment directive to the specified power of two boundary. For
244 /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
245 /// global value is specified, and if that global has an explicit alignment
246 /// requested, it will override the alignment request if required for
249 void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const;
251 /// Lower the specified LLVM Constant to an MCExpr.
252 const MCExpr *lowerConstant(const Constant *CV);
254 /// \brief Print a general LLVM constant to the .s file.
255 void EmitGlobalConstant(const Constant *CV);
257 /// \brief Unnamed constant global variables solely contaning a pointer to
258 /// another globals variable act like a global variable "proxy", or GOT
259 /// equivalents, i.e., it's only used to hold the address of the latter. One
260 /// optimization is to replace accesses to these proxies by using the GOT
261 /// entry for the final global instead. Hence, we select GOT equivalent
262 /// candidates among all the module global variables, avoid emitting them
263 /// unnecessarily and finally replace references to them by pc relative
264 /// accesses to GOT entries.
265 void computeGlobalGOTEquivs(Module &M);
267 /// \brief Constant expressions using GOT equivalent globals may not be
268 /// eligible for PC relative GOT entry conversion, in such cases we need to
269 /// emit the proxies we previously omitted in EmitGlobalVariable.
270 void emitGlobalGOTEquivs();
272 //===------------------------------------------------------------------===//
274 //===------------------------------------------------------------------===//
276 // Targets can, or in the case of EmitInstruction, must implement these to
279 /// This virtual method can be overridden by targets that want to emit
280 /// something at the start of their file.
281 virtual void EmitStartOfAsmFile(Module &) {}
283 /// This virtual method can be overridden by targets that want to emit
284 /// something at the end of their file.
285 virtual void EmitEndOfAsmFile(Module &) {}
287 /// Targets can override this to emit stuff before the first basic block in
289 virtual void EmitFunctionBodyStart() {}
291 /// Targets can override this to emit stuff after the last basic block in the
293 virtual void EmitFunctionBodyEnd() {}
295 /// Targets can override this to emit stuff at the start of a basic block.
296 /// By default, this method prints the label for the specified
297 /// MachineBasicBlock, an alignment (if present) and a comment describing it
299 virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;
301 /// Targets can override this to emit stuff at the end of a basic block.
302 virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB) {}
304 /// Targets should implement this to emit instructions.
305 virtual void EmitInstruction(const MachineInstr *) {
306 llvm_unreachable("EmitInstruction not implemented");
309 /// Return the symbol for the specified constant pool entry.
310 virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
312 virtual void EmitFunctionEntryLabel();
314 virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
316 /// Targets can override this to change how global constants that are part of
317 /// a C++ static/global constructor list are emitted.
318 virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }
320 /// Return true if the basic block has exactly one predecessor and the control
321 /// transfer mechanism between the predecessor and this block is a
324 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
326 /// Targets can override this to customize the output of IMPLICIT_DEF
327 /// instructions in verbose mode.
328 virtual void emitImplicitDef(const MachineInstr *MI) const;
330 //===------------------------------------------------------------------===//
331 // Symbol Lowering Routines.
332 //===------------------------------------------------------------------===//
334 MCSymbol *createTempSymbol(const Twine &Name) const;
336 /// Return the MCSymbol for a private symbol with global value name as its
337 /// base, with the specified suffix.
338 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
339 StringRef Suffix) const;
341 /// Return the MCSymbol for the specified ExternalSymbol.
342 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
344 /// Return the symbol for the specified jump table entry.
345 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
347 /// Return the symbol for the specified jump table .set
348 /// FIXME: privatize to AsmPrinter.
349 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
351 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
353 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
354 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
356 //===------------------------------------------------------------------===//
357 // Emission Helper Routines.
358 //===------------------------------------------------------------------===//
360 /// This is just convenient handler for printing offsets.
361 void printOffset(int64_t Offset, raw_ostream &OS) const;
363 /// Emit a byte directive and value.
365 void EmitInt8(int Value) const;
367 /// Emit a short directive and value.
369 void EmitInt16(int Value) const;
371 /// Emit a long directive and value.
373 void EmitInt32(int Value) const;
375 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
376 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses
377 /// .set if it is available.
378 void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
379 unsigned Size) const;
381 /// Emit something like ".long Label+Offset" where the size in bytes of the
382 /// directive is specified by Size and Label specifies the label. This
383 /// implicitly uses .set if it is available.
384 void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
385 unsigned Size, bool IsSectionRelative = false) const;
387 /// Emit something like ".long Label" where the size in bytes of the directive
388 /// is specified by Size and Label specifies the label.
389 void EmitLabelReference(const MCSymbol *Label, unsigned Size,
390 bool IsSectionRelative = false) const {
391 EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
394 //===------------------------------------------------------------------===//
395 // Dwarf Emission Helper Routines
396 //===------------------------------------------------------------------===//
398 /// Emit the specified signed leb128 value.
399 void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
401 /// Emit the specified unsigned leb128 value.
402 void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
403 unsigned PadTo = 0) const;
405 /// Emit a .byte 42 directive for a DW_CFA_xxx value.
406 void EmitCFAByte(unsigned Val) const;
408 /// Emit a .byte 42 directive that corresponds to an encoding. If verbose
409 /// assembly output is enabled, we output comments describing the encoding.
410 /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
411 void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
413 /// Return the size of the encoding in bytes.
414 unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
416 /// Emit reference to a ttype global with a specified encoding.
417 void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
419 /// Emit the 4-byte offset of Label from the start of its section. This can
420 /// be done with a special directive if the target supports it (e.g. cygwin)
421 /// or by emitting it as an offset from a label at the start of the section.
422 void emitSectionOffset(const MCSymbol *Label) const;
424 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
425 virtual unsigned getISAEncoding() { return 0; }
427 /// EmitDwarfRegOp - Emit a dwarf register operation.
428 virtual void EmitDwarfRegOp(ByteStreamer &BS,
429 const MachineLocation &MLoc) const;
431 //===------------------------------------------------------------------===//
432 // Dwarf Lowering Routines
433 //===------------------------------------------------------------------===//
435 /// \brief Emit frame instruction to describe the layout of the frame.
436 void emitCFIInstruction(const MCCFIInstruction &Inst) const;
438 /// \brief Emit Dwarf abbreviation table.
439 void emitDwarfAbbrevs(const std::vector<DIEAbbrev *>& Abbrevs) const;
441 /// \brief Recursively emit Dwarf DIE tree.
442 void emitDwarfDIE(const DIE &Die) const;
444 //===------------------------------------------------------------------===//
445 // Inline Asm Support
446 //===------------------------------------------------------------------===//
448 // These are hooks that targets can override to implement inline asm
449 // support. These should probably be moved out of AsmPrinter someday.
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
457 virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
458 const char *Code) const;
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,
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
471 virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
472 unsigned AsmVariant, const char *ExtraCode,
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;
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;
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;
495 /// This method emits the header for the current function.
496 void EmitFunctionHeader();
498 /// Emit a blob of inline asm to the output streamer.
500 EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
501 const MDNode *LocMDNode = nullptr,
502 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
504 /// This method formats and emits the specified machine instruction that is an
506 void EmitInlineAsm(const MachineInstr *MI) const;
508 //===------------------------------------------------------------------===//
509 // Internal Implementation Details
510 //===------------------------------------------------------------------===//
512 /// This emits visibility information about symbol, if this is suported by the
514 void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
515 bool IsDefinition = true) const;
517 void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
519 void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
520 const MachineBasicBlock *MBB, unsigned uid) const;
521 void EmitLLVMUsedList(const ConstantArray *InitList);
522 /// Emit llvm.ident metadata in an '.ident' directive.
523 void EmitModuleIdents(Module &M);
524 void EmitXXStructorList(const Constant *List, bool isCtor);
525 GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C);