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;
52 class MCSubtargetInfo;
57 class TargetLoweringObjectFile;
61 /// This class is intended to be used as a driving class for all asm writers.
62 class AsmPrinter : public MachineFunctionPass {
64 /// Target machine description.
68 /// Target Asm Printer information.
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;
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;
82 /// The current machine function.
83 const MachineFunction *MF;
85 /// This is a pointer to the current MachineModuleInfo.
86 MachineModuleInfo *MMI;
88 /// Name-mangler for global names.
92 /// The symbol for the current function. This is recalculated at the beginning
93 /// of each call to runOnMachineFunction().
95 MCSymbol *CurrentFnSym;
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;
103 // The garbage collection metadata printer table.
104 void *GCMetadataPrinters; // Really a DenseMap.
106 /// Emit comments in assembly output if this is true.
111 /// If VerboseAsm is set, a pointer to the loop info for this function.
115 AsmPrinterHandler *Handler;
116 const char *TimerName, *TimerGroupName;
117 HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName,
118 const char *TimerGroupName)
119 : Handler(Handler), TimerName(TimerName),
120 TimerGroupName(TimerGroupName) {}
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;
126 /// If the target supports dwarf debug info, this pointer is non-null.
130 explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
133 virtual ~AsmPrinter();
135 DwarfDebug *getDwarfDebug() { return DD; }
136 DwarfDebug *getDwarfDebug() const { return DD; }
138 /// Return true if assembly output should contain comments.
140 bool isVerbose() const { return VerboseAsm; }
142 /// Return a unique ID for the current function.
144 unsigned getFunctionNumber() const;
146 /// Return information about object file lowering.
147 const TargetLoweringObjectFile &getObjFileLowering() const;
149 /// Return information about data layout.
150 const DataLayout &getDataLayout() const;
152 /// Return information about subtarget.
153 const MCSubtargetInfo &getSubtargetInfo() const;
155 void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
157 /// Return the target triple string.
158 StringRef getTargetTriple() const;
160 /// Return the current section we are emitting to.
161 const MCSection *getCurrentSection() const;
163 void getNameWithPrefix(SmallVectorImpl<char> &Name,
164 const GlobalValue *GV) const;
166 MCSymbol *getSymbol(const GlobalValue *GV) const;
168 //===------------------------------------------------------------------===//
169 // MachineFunctionPass Implementation.
170 //===------------------------------------------------------------------===//
172 /// Record analysis usage.
174 void getAnalysisUsage(AnalysisUsage &AU) const override;
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;
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;
184 /// Emit the specified function out to the OutStreamer.
185 bool runOnMachineFunction(MachineFunction &MF) override {
186 SetupMachineFunction(MF);
187 EmitFunctionHeader();
192 //===------------------------------------------------------------------===//
193 // Coarse grained IR lowering routines.
194 //===------------------------------------------------------------------===//
196 /// This should be called when a new MachineFunction is being processed from
197 /// runOnMachineFunction.
198 void SetupMachineFunction(MachineFunction &MF);
200 /// This method emits the header for the current function.
201 void EmitFunctionHeader();
203 /// This method emits the body and trailer for a function.
204 void EmitFunctionBody();
206 void emitCFIInstruction(const MachineInstr &MI);
208 void emitFrameAlloc(const MachineInstr &MI);
210 enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
211 CFIMoveType needsCFIMoves();
213 bool needsSEHMoves();
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.
219 virtual void EmitConstantPool();
221 /// Print assembly representations of the jump tables used by the current
222 /// function to the current output stream.
224 void EmitJumpTableInfo();
226 /// Emit the specified global variable to the .s file.
227 virtual void EmitGlobalVariable(const GlobalVariable *GV);
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);
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
239 void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const;
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;
245 /// Lower the specified LLVM Constant to an MCExpr.
246 const MCExpr *lowerConstant(const Constant *CV);
248 /// \brief Print a general LLVM constant to the .s file.
249 void EmitGlobalConstant(const Constant *CV);
251 //===------------------------------------------------------------------===//
253 //===------------------------------------------------------------------===//
255 // Targets can, or in the case of EmitInstruction, must implement these to
258 /// This virtual method can be overridden by targets that want to emit
259 /// something at the start of their file.
260 virtual void EmitStartOfAsmFile(Module &) {}
262 /// This virtual method can be overridden by targets that want to emit
263 /// something at the end of their file.
264 virtual void EmitEndOfAsmFile(Module &) {}
266 /// Targets can override this to emit stuff before the first basic block in
268 virtual void EmitFunctionBodyStart() {}
270 /// Targets can override this to emit stuff after the last basic block in the
272 virtual void EmitFunctionBodyEnd() {}
274 /// Targets can override this to emit stuff at the end of a basic block.
275 virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB) {}
277 /// Targets should implement this to emit instructions.
278 virtual void EmitInstruction(const MachineInstr *) {
279 llvm_unreachable("EmitInstruction not implemented");
282 /// Return the symbol for the specified constant pool entry.
283 virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
285 virtual void EmitFunctionEntryLabel();
287 virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
289 /// Targets can override this to change how global constants that are part of
290 /// a C++ static/global constructor list are emitted.
291 virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }
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
297 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
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;
303 //===------------------------------------------------------------------===//
304 // Symbol Lowering Routines.
305 //===------------------------------------------------------------------===//
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;
311 /// Return an assembler temporary label with the specified stem.
312 MCSymbol *GetTempSymbol(Twine Name) const;
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;
319 /// Return the MCSymbol for the specified ExternalSymbol.
320 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
322 /// Return the symbol for the specified jump table entry.
323 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
325 /// Return the symbol for the specified jump table .set
326 /// FIXME: privatize to AsmPrinter.
327 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
329 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
331 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
332 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
334 //===------------------------------------------------------------------===//
335 // Emission Helper Routines.
336 //===------------------------------------------------------------------===//
338 /// This is just convenient handler for printing offsets.
339 void printOffset(int64_t Offset, raw_ostream &OS) const;
341 /// Emit a byte directive and value.
343 void EmitInt8(int Value) const;
345 /// Emit a short directive and value.
347 void EmitInt16(int Value) const;
349 /// Emit a long directive and value.
351 void EmitInt32(int Value) const;
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;
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;
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);
372 //===------------------------------------------------------------------===//
373 // Dwarf Emission Helper Routines
374 //===------------------------------------------------------------------===//
376 /// Emit the specified signed leb128 value.
377 void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
379 /// Emit the specified unsigned leb128 value.
380 void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
381 unsigned PadTo = 0) const;
383 /// Emit a .byte 42 directive for a DW_CFA_xxx value.
384 void EmitCFAByte(unsigned Val) const;
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;
391 /// Return the size of the encoding in bytes.
392 unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
394 /// Emit reference to a ttype global with a specified encoding.
395 void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
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.
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;
406 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
407 virtual unsigned getISAEncoding() { return 0; }
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;
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.
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;
432 /// EmitDwarfRegOp - Emit a dwarf register operation.
433 /// \param Indirect whether this is a register-indirect address
434 virtual void EmitDwarfRegOp(ByteStreamer &BS,
435 const MachineLocation &MLoc) const;
437 //===------------------------------------------------------------------===//
438 // Dwarf Lowering Routines
439 //===------------------------------------------------------------------===//
441 /// \brief Emit frame instruction to describe the layout of the frame.
442 void emitCFIInstruction(const MCCFIInstruction &Inst) 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 MCSubtargetInfo &StartInfo) 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;
494 mutable unsigned SetCounter;
496 /// Emit a blob of inline asm to the output streamer.
498 EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = nullptr,
499 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
501 /// This method formats and emits the specified machine instruction that is an
503 void EmitInlineAsm(const MachineInstr *MI) const;
505 //===------------------------------------------------------------------===//
506 // Internal Implementation Details
507 //===------------------------------------------------------------------===//
509 /// This emits visibility information about symbol, if this is suported by the
511 void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
512 bool IsDefinition = true) const;
514 void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
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);