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/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"
26 class AsmPrinterHandler;
32 class GCMetadataPrinter;
35 class MachineBasicBlock;
36 class MachineFunction;
38 class MachineLocation;
39 class MachineLoopInfo;
41 class MachineConstantPoolValue;
42 class MachineJumpTableInfo;
43 class MachineModuleInfo;
45 class MCCFIInstruction;
51 class MCSubtargetInfo;
56 class TargetLoweringObjectFile;
60 /// This class is intended to be used as a driving class for all asm writers.
61 class AsmPrinter : public MachineFunctionPass {
63 /// Target machine description.
67 /// Target Asm Printer information.
71 const MCInstrInfo *MII;
72 /// This is the context for the output file that we are streaming. This owns
73 /// all of the global MC-related objects for the generated translation unit.
74 MCContext &OutContext;
76 /// This is the MCStreamer object for the file we are generating. This
77 /// contains the transient state for the current translation unit that we are
78 /// generating (such as the current section etc).
79 MCStreamer &OutStreamer;
81 /// The current machine function.
82 const MachineFunction *MF;
84 /// This is a pointer to the current MachineModuleInfo.
85 MachineModuleInfo *MMI;
87 /// Name-mangler for global names.
91 /// The symbol for the current function. This is recalculated at the beginning
92 /// of each call to runOnMachineFunction().
94 MCSymbol *CurrentFnSym;
96 /// The symbol used to represent the start of the current function for the
97 /// purpose of calculating its size (e.g. using the .size directive). By
98 /// default, this is equal to CurrentFnSym.
99 MCSymbol *CurrentFnSymForSize;
102 // The garbage collection metadata printer table.
103 void *GCMetadataPrinters; // Really a DenseMap.
105 /// Emit comments in assembly output if this is true.
110 /// If VerboseAsm is set, a pointer to the loop info for this function.
114 AsmPrinterHandler *Handler;
115 const char *TimerName, *TimerGroupName;
116 HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName,
117 const char *TimerGroupName)
118 : Handler(Handler), TimerName(TimerName),
119 TimerGroupName(TimerGroupName) {}
121 /// A vector of all debug/EH info emitters we should use. This vector
122 /// maintains ownership of the emitters.
123 SmallVector<HandlerInfo, 1> Handlers;
125 /// If the target supports dwarf debug info, this pointer is non-null.
129 explicit AsmPrinter(TargetMachine &TM, MCStreamer &Streamer);
132 virtual ~AsmPrinter();
134 DwarfDebug *getDwarfDebug() { return DD; }
136 /// Return true if assembly output should contain comments.
138 bool isVerbose() const { return VerboseAsm; }
140 /// Return a unique ID for the current function.
142 unsigned getFunctionNumber() const;
144 /// Return information about object file lowering.
145 const TargetLoweringObjectFile &getObjFileLowering() const;
147 /// Return information about data layout.
148 const DataLayout &getDataLayout() const;
150 /// Return information about subtarget.
151 const MCSubtargetInfo &getSubtargetInfo() const;
153 void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
155 /// Return the target triple string.
156 StringRef getTargetTriple() const;
158 /// Return the current section we are emitting to.
159 const MCSection *getCurrentSection() const;
161 void getNameWithPrefix(SmallVectorImpl<char> &Name,
162 const GlobalValue *GV) const;
164 MCSymbol *getSymbol(const GlobalValue *GV) const;
166 //===------------------------------------------------------------------===//
167 // MachineFunctionPass Implementation.
168 //===------------------------------------------------------------------===//
170 /// Record analysis usage.
172 void getAnalysisUsage(AnalysisUsage &AU) const override;
174 /// Set up the AsmPrinter when we are working on a new module. If your pass
175 /// overrides this, it must make sure to explicitly call this implementation.
176 bool doInitialization(Module &M) override;
178 /// Shut down the asmprinter. If you override this in your pass, you must make
179 /// sure to call it explicitly.
180 bool doFinalization(Module &M) override;
182 /// Emit the specified function out to the OutStreamer.
183 bool runOnMachineFunction(MachineFunction &MF) override {
184 SetupMachineFunction(MF);
185 EmitFunctionHeader();
190 //===------------------------------------------------------------------===//
191 // Coarse grained IR lowering routines.
192 //===------------------------------------------------------------------===//
194 /// This should be called when a new MachineFunction is being processed from
195 /// runOnMachineFunction.
196 void SetupMachineFunction(MachineFunction &MF);
198 /// This method emits the header for the current function.
199 void EmitFunctionHeader();
201 /// This method emits the body and trailer for a function.
202 void EmitFunctionBody();
204 void emitCFIInstruction(const MachineInstr &MI);
206 enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
207 CFIMoveType needsCFIMoves();
209 bool needsSEHMoves();
211 /// Print to the current output stream assembly representations of the
212 /// constants in the constant pool MCP. This is used to print out constants
213 /// which have been "spilled to memory" by the code generator.
215 virtual void EmitConstantPool();
217 /// Print assembly representations of the jump tables used by the current
218 /// function to the current output stream.
220 void EmitJumpTableInfo();
222 /// Emit the specified global variable to the .s file.
223 virtual void EmitGlobalVariable(const GlobalVariable *GV);
225 /// Check to see if the specified global is a special global used by LLVM. If
226 /// so, emit it and return true, otherwise do nothing and return false.
227 bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
229 /// Emit an alignment directive to the specified power of two boundary. For
230 /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
231 /// global value is specified, and if that global has an explicit alignment
232 /// requested, it will override the alignment request if required for
235 void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const;
237 /// This method prints the label for the specified MachineBasicBlock, an
238 /// alignment (if present) and a comment describing it if appropriate.
239 void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;
241 /// \brief Print a general LLVM constant to the .s file.
242 void EmitGlobalConstant(const Constant *CV);
244 //===------------------------------------------------------------------===//
246 //===------------------------------------------------------------------===//
248 // Targets can, or in the case of EmitInstruction, must implement these to
251 /// This virtual method can be overridden by targets that want to emit
252 /// something at the start of their file.
253 virtual void EmitStartOfAsmFile(Module &) {}
255 /// This virtual method can be overridden by targets that want to emit
256 /// something at the end of their file.
257 virtual void EmitEndOfAsmFile(Module &) {}
259 /// Targets can override this to emit stuff before the first basic block in
261 virtual void EmitFunctionBodyStart() {}
263 /// Targets can override this to emit stuff after the last basic block in the
265 virtual void EmitFunctionBodyEnd() {}
267 /// Targets should implement this to emit instructions.
268 virtual void EmitInstruction(const MachineInstr *) {
269 llvm_unreachable("EmitInstruction not implemented");
272 /// Return the symbol for the specified constant pool entry.
273 virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
275 virtual void EmitFunctionEntryLabel();
277 virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
279 /// Targets can override this to change how global constants that are part of
280 /// a C++ static/global constructor list are emitted.
281 virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }
283 /// Return true if the basic block has exactly one predecessor and the control
284 /// transfer mechanism between the predecessor and this block is a
287 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
289 /// Targets can override this to customize the output of IMPLICIT_DEF
290 /// instructions in verbose mode.
291 virtual void emitImplicitDef(const MachineInstr *MI) const;
293 //===------------------------------------------------------------------===//
294 // Symbol Lowering Routines.
295 //===------------------------------------------------------------------===//
297 /// Return the MCSymbol corresponding to the assembler temporary label with
298 /// the specified stem and unique ID.
299 MCSymbol *GetTempSymbol(Twine Name, unsigned ID) const;
301 /// Return an assembler temporary label with the specified stem.
302 MCSymbol *GetTempSymbol(Twine Name) const;
304 /// Return the MCSymbol for a private symbol with global value name as its
305 /// base, with the specified suffix.
306 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
307 StringRef Suffix) const;
309 /// Return the MCSymbol for the specified ExternalSymbol.
310 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
312 /// Return the symbol for the specified jump table entry.
313 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
315 /// Return the symbol for the specified jump table .set
316 /// FIXME: privatize to AsmPrinter.
317 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
319 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
321 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
322 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
324 //===------------------------------------------------------------------===//
325 // Emission Helper Routines.
326 //===------------------------------------------------------------------===//
328 /// This is just convenient handler for printing offsets.
329 void printOffset(int64_t Offset, raw_ostream &OS) const;
331 /// Emit a byte directive and value.
333 void EmitInt8(int Value) const;
335 /// Emit a short directive and value.
337 void EmitInt16(int Value) const;
339 /// Emit a long directive and value.
341 void EmitInt32(int Value) const;
343 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
344 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses
345 /// .set if it is available.
346 void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
347 unsigned Size) const;
349 /// Emit something like ".long Hi+Offset-Lo" where the size in bytes of the
350 /// directive is specified by Size and Hi/Lo specify the labels. This
351 /// implicitly uses .set if it is available.
352 void EmitLabelOffsetDifference(const MCSymbol *Hi, uint64_t Offset,
353 const MCSymbol *Lo, unsigned Size) const;
355 /// Emit something like ".long Label+Offset" where the size in bytes of the
356 /// directive is specified by Size and Label specifies the label. This
357 /// implicitly uses .set if it is available.
358 void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
359 unsigned Size, bool IsSectionRelative = false) const;
361 /// Emit something like ".long Label" where the size in bytes of the directive
362 /// is specified by Size and Label specifies the label.
363 void EmitLabelReference(const MCSymbol *Label, unsigned Size,
364 bool IsSectionRelative = false) const {
365 EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
368 //===------------------------------------------------------------------===//
369 // Dwarf Emission Helper Routines
370 //===------------------------------------------------------------------===//
372 /// Emit the specified signed leb128 value.
373 void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
375 /// Emit the specified unsigned leb128 value.
376 void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
377 unsigned PadTo = 0) const;
379 /// Emit a .byte 42 directive for a DW_CFA_xxx value.
380 void EmitCFAByte(unsigned Val) const;
382 /// Emit a .byte 42 directive that corresponds to an encoding. If verbose
383 /// assembly output is enabled, we output comments describing the encoding.
384 /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
385 void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
387 /// Return the size of the encoding in bytes.
388 unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
390 /// Emit reference to a ttype global with a specified encoding.
391 void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
393 /// Emit the 4-byte offset of Label from the start of its section. This can
394 /// be done with a special directive if the target supports it (e.g. cygwin)
395 /// or by emitting it as an offset from a label at the start of the section.
397 /// SectionLabel is a temporary label emitted at the start of the section
398 /// that Label lives in.
399 void EmitSectionOffset(const MCSymbol *Label,
400 const MCSymbol *SectionLabel) const;
402 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
403 virtual unsigned getISAEncoding() { return 0; }
405 /// \brief Emit a partial DWARF register operation.
406 /// \param MLoc the register
407 /// \param PieceSize size and
408 /// \param PieceOffset offset of the piece in bits, if this is one
409 /// piece of an aggregate value.
411 /// If size and offset is zero an operation for the entire
412 /// register is emitted: Some targets do not provide a DWARF
413 /// register number for every register. If this is the case, this
414 /// function will attempt to emit a DWARF register by emitting a
415 /// piece of a super-register or by piecing together multiple
416 /// subregisters that alias the register.
417 void EmitDwarfRegOpPiece(ByteStreamer &BS, const MachineLocation &MLoc,
418 unsigned PieceSize = 0,
419 unsigned PieceOffset = 0) const;
421 /// Emit dwarf register operation.
422 /// \param Indirect whether this is a register-indirect address
423 virtual void EmitDwarfRegOp(ByteStreamer &BS, const MachineLocation &MLoc,
424 bool Indirect) const;
426 //===------------------------------------------------------------------===//
427 // Dwarf Lowering Routines
428 //===------------------------------------------------------------------===//
430 /// \brief Emit frame instruction to describe the layout of the frame.
431 void emitCFIInstruction(const MCCFIInstruction &Inst) const;
433 //===------------------------------------------------------------------===//
434 // Inline Asm Support
435 //===------------------------------------------------------------------===//
437 // These are hooks that targets can override to implement inline asm
438 // support. These should probably be moved out of AsmPrinter someday.
440 /// Print information related to the specified machine instr that is
441 /// independent of the operand, and may be independent of the instr itself.
442 /// This can be useful for portably encoding the comment character or other
443 /// bits of target-specific knowledge into the asmstrings. The syntax used is
444 /// ${:comment}. Targets can override this to add support for their own
446 virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
447 const char *Code) const;
449 /// Print the specified operand of MI, an INLINEASM instruction, using the
450 /// specified assembler variant. Targets should override this to format as
451 /// appropriate. This method can return true if the operand is erroneous.
452 virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
453 unsigned AsmVariant, const char *ExtraCode,
456 /// Print the specified operand of MI, an INLINEASM instruction, using the
457 /// specified assembler variant as an address. Targets should override this to
458 /// format as appropriate. This method can return true if the operand is
460 virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
461 unsigned AsmVariant, const char *ExtraCode,
464 /// Let the target do anything it needs to do after emitting inlineasm.
465 /// This callback can be used restore the original mode in case the
466 /// inlineasm contains directives to switch modes.
467 /// \p StartInfo - the original subtarget info before inline asm
468 /// \p EndInfo - the final subtarget info after parsing the inline asm,
469 /// or NULL if the value is unknown.
470 virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
471 const MCSubtargetInfo *EndInfo) const;
474 /// Private state for PrintSpecial()
475 // Assign a unique ID to this machine instruction.
476 mutable const MachineInstr *LastMI;
477 mutable unsigned LastFn;
478 mutable unsigned Counter;
479 mutable unsigned SetCounter;
481 /// Emit a blob of inline asm to the output streamer.
483 EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = nullptr,
484 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
486 /// This method formats and emits the specified machine instruction that is an
488 void EmitInlineAsm(const MachineInstr *MI) const;
490 //===------------------------------------------------------------------===//
491 // Internal Implementation Details
492 //===------------------------------------------------------------------===//
494 /// This emits visibility information about symbol, if this is suported by the
496 void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
497 bool IsDefinition = true) const;
499 void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
501 void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
502 const MachineBasicBlock *MBB, unsigned uid) const;
503 void EmitLLVMUsedList(const ConstantArray *InitList);
504 /// Emit llvm.ident metadata in an '.ident' directive.
505 void EmitModuleIdents(Module &M);
506 void EmitXXStructorList(const Constant *List, bool isCtor);
507 GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C);