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 /// Lower the specified LLVM Constant to an MCExpr.
242 const MCExpr *lowerConstant(const Constant *CV);
244 /// \brief Print a general LLVM constant to the .s file.
245 void EmitGlobalConstant(const Constant *CV);
247 //===------------------------------------------------------------------===//
249 //===------------------------------------------------------------------===//
251 // Targets can, or in the case of EmitInstruction, must implement these to
254 /// This virtual method can be overridden by targets that want to emit
255 /// something at the start of their file.
256 virtual void EmitStartOfAsmFile(Module &) {}
258 /// This virtual method can be overridden by targets that want to emit
259 /// something at the end of their file.
260 virtual void EmitEndOfAsmFile(Module &) {}
262 /// Targets can override this to emit stuff before the first basic block in
264 virtual void EmitFunctionBodyStart() {}
266 /// Targets can override this to emit stuff after the last basic block in the
268 virtual void EmitFunctionBodyEnd() {}
270 /// Targets can override this to emit stuff at the start of a basic block.
271 /// By default, this method prints the label for the specified
272 /// MachineBasicBlock, an alignment (if present) and a comment describing it
274 virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;
276 /// Targets can override this to emit stuff at the end of a basic block.
277 virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB) {}
279 /// Targets should implement this to emit instructions.
280 virtual void EmitInstruction(const MachineInstr *) {
281 llvm_unreachable("EmitInstruction not implemented");
284 /// Return the symbol for the specified constant pool entry.
285 virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
287 virtual void EmitFunctionEntryLabel();
289 virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
291 /// Targets can override this to change how global constants that are part of
292 /// a C++ static/global constructor list are emitted.
293 virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }
295 /// Return true if the basic block has exactly one predecessor and the control
296 /// transfer mechanism between the predecessor and this block is a
299 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
301 /// Targets can override this to customize the output of IMPLICIT_DEF
302 /// instructions in verbose mode.
303 virtual void emitImplicitDef(const MachineInstr *MI) const;
305 //===------------------------------------------------------------------===//
306 // Symbol Lowering Routines.
307 //===------------------------------------------------------------------===//
309 /// Return the MCSymbol corresponding to the assembler temporary label with
310 /// the specified stem and unique ID.
311 MCSymbol *GetTempSymbol(const Twine &Name, unsigned ID) const;
313 /// Return an assembler temporary label with the specified stem.
314 MCSymbol *GetTempSymbol(const Twine &Name) const;
316 /// Return the MCSymbol for a private symbol with global value name as its
317 /// base, with the specified suffix.
318 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
319 StringRef Suffix) const;
321 /// Return the MCSymbol for the specified ExternalSymbol.
322 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
324 /// Return the symbol for the specified jump table entry.
325 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
327 /// Return the symbol for the specified jump table .set
328 /// FIXME: privatize to AsmPrinter.
329 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
331 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
333 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
334 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
336 //===------------------------------------------------------------------===//
337 // Emission Helper Routines.
338 //===------------------------------------------------------------------===//
340 /// This is just convenient handler for printing offsets.
341 void printOffset(int64_t Offset, raw_ostream &OS) const;
343 /// Emit a byte directive and value.
345 void EmitInt8(int Value) const;
347 /// Emit a short directive and value.
349 void EmitInt16(int Value) const;
351 /// Emit a long directive and value.
353 void EmitInt32(int Value) const;
355 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
356 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses
357 /// .set if it is available.
358 void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
359 unsigned Size) const;
361 /// Emit something like ".long Label+Offset" where the size in bytes of the
362 /// directive is specified by Size and Label specifies the label. This
363 /// implicitly uses .set if it is available.
364 void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
365 unsigned Size, bool IsSectionRelative = false) const;
367 /// Emit something like ".long Label" where the size in bytes of the directive
368 /// is specified by Size and Label specifies the label.
369 void EmitLabelReference(const MCSymbol *Label, unsigned Size,
370 bool IsSectionRelative = false) const {
371 EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
374 //===------------------------------------------------------------------===//
375 // Dwarf Emission Helper Routines
376 //===------------------------------------------------------------------===//
378 /// Emit the specified signed leb128 value.
379 void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
381 /// Emit the specified unsigned leb128 value.
382 void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
383 unsigned PadTo = 0) const;
385 /// Emit a .byte 42 directive for a DW_CFA_xxx value.
386 void EmitCFAByte(unsigned Val) const;
388 /// Emit a .byte 42 directive that corresponds to an encoding. If verbose
389 /// assembly output is enabled, we output comments describing the encoding.
390 /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
391 void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
393 /// Return the size of the encoding in bytes.
394 unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
396 /// Emit reference to a ttype global with a specified encoding.
397 void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
399 /// Emit the 4-byte offset of Label from the start of its section. This can
400 /// be done with a special directive if the target supports it (e.g. cygwin)
401 /// or by emitting it as an offset from a label at the start of the section.
403 /// SectionLabel is a temporary label emitted at the start of the section
404 /// that Label lives in.
405 void EmitSectionOffset(const MCSymbol *Label,
406 const MCSymbol *SectionLabel) const;
408 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
409 virtual unsigned getISAEncoding(const Function *) { return 0; }
411 /// Emit a dwarf register operation for describing
412 /// - a small value occupying only part of a register or
413 /// - a register representing only part of a value.
414 void EmitDwarfOpPiece(ByteStreamer &Streamer, unsigned SizeInBits,
415 unsigned OffsetInBits = 0) const;
418 /// \brief Emit a partial DWARF register operation.
419 /// \param MLoc the register
420 /// \param PieceSize size and
421 /// \param PieceOffset offset of the piece in bits, if this is one
422 /// piece of an aggregate value.
424 /// If size and offset is zero an operation for the entire
425 /// register is emitted: Some targets do not provide a DWARF
426 /// register number for every register. If this is the case, this
427 /// function will attempt to emit a DWARF register by emitting a
428 /// piece of a super-register or by piecing together multiple
429 /// subregisters that alias the register.
430 void EmitDwarfRegOpPiece(ByteStreamer &BS, const MachineLocation &MLoc,
431 unsigned PieceSize = 0,
432 unsigned PieceOffset = 0) const;
434 /// EmitDwarfRegOp - Emit a dwarf register operation.
435 virtual void EmitDwarfRegOp(ByteStreamer &BS,
436 const MachineLocation &MLoc) const;
438 //===------------------------------------------------------------------===//
439 // Dwarf Lowering Routines
440 //===------------------------------------------------------------------===//
442 /// \brief Emit frame instruction to describe the layout of the frame.
443 void emitCFIInstruction(const MCCFIInstruction &Inst) const;
445 //===------------------------------------------------------------------===//
446 // Inline Asm Support
447 //===------------------------------------------------------------------===//
449 // These are hooks that targets can override to implement inline asm
450 // support. These should probably be moved out of AsmPrinter someday.
452 /// Print information related to the specified machine instr that is
453 /// independent of the operand, and may be independent of the instr itself.
454 /// This can be useful for portably encoding the comment character or other
455 /// bits of target-specific knowledge into the asmstrings. The syntax used is
456 /// ${:comment}. Targets can override this to add support for their own
458 virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
459 const char *Code) const;
461 /// Print the specified operand of MI, an INLINEASM instruction, using the
462 /// specified assembler variant. Targets should override this to format as
463 /// appropriate. This method can return true if the operand is erroneous.
464 virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
465 unsigned AsmVariant, const char *ExtraCode,
468 /// Print the specified operand of MI, an INLINEASM instruction, using the
469 /// specified assembler variant as an address. Targets should override this to
470 /// format as appropriate. This method can return true if the operand is
472 virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
473 unsigned AsmVariant, const char *ExtraCode,
476 /// Let the target do anything it needs to do before emitting inlineasm.
477 /// \p StartInfo - the subtarget info before parsing inline asm
478 virtual void emitInlineAsmStart(const MCSubtargetInfo &StartInfo) const;
480 /// Let the target do anything it needs to do after emitting inlineasm.
481 /// This callback can be used restore the original mode in case the
482 /// inlineasm contains directives to switch modes.
483 /// \p StartInfo - the original subtarget info before inline asm
484 /// \p EndInfo - the final subtarget info after parsing the inline asm,
485 /// or NULL if the value is unknown.
486 virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
487 const MCSubtargetInfo *EndInfo) const;
490 /// Private state for PrintSpecial()
491 // Assign a unique ID to this machine instruction.
492 mutable const MachineInstr *LastMI;
493 mutable unsigned LastFn;
494 mutable unsigned Counter;
495 mutable unsigned SetCounter;
497 /// Emit a blob of inline asm to the output streamer.
499 EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = nullptr,
500 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
502 /// This method formats and emits the specified machine instruction that is an
504 void EmitInlineAsm(const MachineInstr *MI) const;
506 //===------------------------------------------------------------------===//
507 // Internal Implementation Details
508 //===------------------------------------------------------------------===//
510 /// This emits visibility information about symbol, if this is suported by the
512 void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
513 bool IsDefinition = true) const;
515 void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
517 void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
518 const MachineBasicBlock *MBB, unsigned uid) const;
519 void EmitLLVMUsedList(const ConstantArray *InitList);
520 /// Emit llvm.ident metadata in an '.ident' directive.
521 void EmitModuleIdents(Module &M);
522 void EmitXXStructorList(const Constant *List, bool isCtor);
523 GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C);