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;
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, MCStreamer &Streamer);
133 virtual ~AsmPrinter();
135 DwarfDebug *getDwarfDebug() { return DD; }
137 /// Return true if assembly output should contain comments.
139 bool isVerbose() const { return VerboseAsm; }
141 /// Return a unique ID for the current function.
143 unsigned getFunctionNumber() const;
145 /// Return information about object file lowering.
146 const TargetLoweringObjectFile &getObjFileLowering() const;
148 /// Return information about data layout.
149 const DataLayout &getDataLayout() const;
151 /// Return information about subtarget.
152 const MCSubtargetInfo &getSubtargetInfo() const;
154 void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
156 /// Return the target triple string.
157 StringRef getTargetTriple() const;
159 /// Return the current section we are emitting to.
160 const MCSection *getCurrentSection() const;
162 void getNameWithPrefix(SmallVectorImpl<char> &Name,
163 const GlobalValue *GV) const;
165 MCSymbol *getSymbol(const GlobalValue *GV) const;
167 //===------------------------------------------------------------------===//
168 // MachineFunctionPass Implementation.
169 //===------------------------------------------------------------------===//
171 /// Record analysis usage.
173 void getAnalysisUsage(AnalysisUsage &AU) const override;
175 /// Set up the AsmPrinter when we are working on a new module. If your pass
176 /// overrides this, it must make sure to explicitly call this implementation.
177 bool doInitialization(Module &M) override;
179 /// Shut down the asmprinter. If you override this in your pass, you must make
180 /// sure to call it explicitly.
181 bool doFinalization(Module &M) override;
183 /// Emit the specified function out to the OutStreamer.
184 bool runOnMachineFunction(MachineFunction &MF) override {
185 SetupMachineFunction(MF);
186 EmitFunctionHeader();
191 //===------------------------------------------------------------------===//
192 // Coarse grained IR lowering routines.
193 //===------------------------------------------------------------------===//
195 /// This should be called when a new MachineFunction is being processed from
196 /// runOnMachineFunction.
197 void SetupMachineFunction(MachineFunction &MF);
199 /// This method emits the header for the current function.
200 void EmitFunctionHeader();
202 /// This method emits the body and trailer for a function.
203 void EmitFunctionBody();
205 void emitCFIInstruction(const MachineInstr &MI);
207 enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
208 CFIMoveType needsCFIMoves();
210 bool needsSEHMoves();
212 /// Print to the current output stream assembly representations of the
213 /// constants in the constant pool MCP. This is used to print out constants
214 /// which have been "spilled to memory" by the code generator.
216 virtual void EmitConstantPool();
218 /// Print assembly representations of the jump tables used by the current
219 /// function to the current output stream.
221 void EmitJumpTableInfo();
223 /// Emit the specified global variable to the .s file.
224 virtual void EmitGlobalVariable(const GlobalVariable *GV);
226 /// Check to see if the specified global is a special global used by LLVM. If
227 /// so, emit it and return true, otherwise do nothing and return false.
228 bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
230 /// Emit an alignment directive to the specified power of two boundary. For
231 /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
232 /// global value is specified, and if that global has an explicit alignment
233 /// requested, it will override the alignment request if required for
236 void EmitAlignment(unsigned NumBits, const GlobalValue *GV = nullptr) const;
238 /// This method prints the label for the specified MachineBasicBlock, an
239 /// alignment (if present) and a comment describing it if appropriate.
240 void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;
242 /// \brief Print a general LLVM constant to the .s file.
243 void EmitGlobalConstant(const Constant *CV);
245 //===------------------------------------------------------------------===//
247 //===------------------------------------------------------------------===//
249 // Targets can, or in the case of EmitInstruction, must implement these to
252 /// This virtual method can be overridden by targets that want to emit
253 /// something at the start of their file.
254 virtual void EmitStartOfAsmFile(Module &) {}
256 /// This virtual method can be overridden by targets that want to emit
257 /// something at the end of their file.
258 virtual void EmitEndOfAsmFile(Module &) {}
260 /// Targets can override this to emit stuff before the first basic block in
262 virtual void EmitFunctionBodyStart() {}
264 /// Targets can override this to emit stuff after the last basic block in the
266 virtual void EmitFunctionBodyEnd() {}
268 /// Targets should implement this to emit instructions.
269 virtual void EmitInstruction(const MachineInstr *) {
270 llvm_unreachable("EmitInstruction not implemented");
273 /// Return the symbol for the specified constant pool entry.
274 virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
276 virtual void EmitFunctionEntryLabel();
278 virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
280 /// Targets can override this to change how global constants that are part of
281 /// a C++ static/global constructor list are emitted.
282 virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }
284 /// Return true if the basic block has exactly one predecessor and the control
285 /// transfer mechanism between the predecessor and this block is a
288 isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
290 /// Targets can override this to customize the output of IMPLICIT_DEF
291 /// instructions in verbose mode.
292 virtual void emitImplicitDef(const MachineInstr *MI) const;
294 //===------------------------------------------------------------------===//
295 // Symbol Lowering Routines.
296 //===------------------------------------------------------------------===//
298 /// Return the MCSymbol corresponding to the assembler temporary label with
299 /// the specified stem and unique ID.
300 MCSymbol *GetTempSymbol(Twine Name, unsigned ID) const;
302 /// Return an assembler temporary label with the specified stem.
303 MCSymbol *GetTempSymbol(Twine Name) const;
305 /// Return the MCSymbol for a private symbol with global value name as its
306 /// base, with the specified suffix.
307 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
308 StringRef Suffix) const;
310 /// Return the MCSymbol for the specified ExternalSymbol.
311 MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
313 /// Return the symbol for the specified jump table entry.
314 MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
316 /// Return the symbol for the specified jump table .set
317 /// FIXME: privatize to AsmPrinter.
318 MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
320 /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
322 MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
323 MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
325 //===------------------------------------------------------------------===//
326 // Emission Helper Routines.
327 //===------------------------------------------------------------------===//
329 /// This is just convenient handler for printing offsets.
330 void printOffset(int64_t Offset, raw_ostream &OS) const;
332 /// Emit a byte directive and value.
334 void EmitInt8(int Value) const;
336 /// Emit a short directive and value.
338 void EmitInt16(int Value) const;
340 /// Emit a long directive and value.
342 void EmitInt32(int Value) const;
344 /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
345 /// is specified by Size and Hi/Lo specify the labels. This implicitly uses
346 /// .set if it is available.
347 void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
348 unsigned Size) const;
350 /// Emit something like ".long Hi+Offset-Lo" where the size in bytes of the
351 /// directive is specified by Size and Hi/Lo specify the labels. This
352 /// implicitly uses .set if it is available.
353 void EmitLabelOffsetDifference(const MCSymbol *Hi, uint64_t Offset,
354 const MCSymbol *Lo, unsigned Size) const;
356 /// Emit something like ".long Label+Offset" where the size in bytes of the
357 /// directive is specified by Size and Label specifies the label. This
358 /// implicitly uses .set if it is available.
359 void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
360 unsigned Size, bool IsSectionRelative = false) const;
362 /// Emit something like ".long Label" where the size in bytes of the directive
363 /// is specified by Size and Label specifies the label.
364 void EmitLabelReference(const MCSymbol *Label, unsigned Size,
365 bool IsSectionRelative = false) const {
366 EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
369 //===------------------------------------------------------------------===//
370 // Dwarf Emission Helper Routines
371 //===------------------------------------------------------------------===//
373 /// Emit the specified signed leb128 value.
374 void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
376 /// Emit the specified unsigned leb128 value.
377 void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
378 unsigned PadTo = 0) const;
380 /// Emit a .byte 42 directive for a DW_CFA_xxx value.
381 void EmitCFAByte(unsigned Val) const;
383 /// Emit a .byte 42 directive that corresponds to an encoding. If verbose
384 /// assembly output is enabled, we output comments describing the encoding.
385 /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
386 void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
388 /// Return the size of the encoding in bytes.
389 unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
391 /// Emit reference to a ttype global with a specified encoding.
392 void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
394 /// Emit the 4-byte offset of Label from the start of its section. This can
395 /// be done with a special directive if the target supports it (e.g. cygwin)
396 /// or by emitting it as an offset from a label at the start of the section.
398 /// SectionLabel is a temporary label emitted at the start of the section
399 /// that Label lives in.
400 void EmitSectionOffset(const MCSymbol *Label,
401 const MCSymbol *SectionLabel) const;
403 /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
404 virtual unsigned getISAEncoding() { return 0; }
406 /// \brief Emit a partial DWARF register operation.
407 /// \param MLoc the register
408 /// \param PieceSize size and
409 /// \param PieceOffset offset of the piece in bits, if this is one
410 /// piece of an aggregate value.
412 /// If size and offset is zero an operation for the entire
413 /// register is emitted: Some targets do not provide a DWARF
414 /// register number for every register. If this is the case, this
415 /// function will attempt to emit a DWARF register by emitting a
416 /// piece of a super-register or by piecing together multiple
417 /// subregisters that alias the register.
418 void EmitDwarfRegOpPiece(ByteStreamer &BS, const MachineLocation &MLoc,
419 unsigned PieceSize = 0,
420 unsigned PieceOffset = 0) const;
422 /// Emit dwarf register operation.
423 /// \param Indirect whether this is a register-indirect address
424 virtual void EmitDwarfRegOp(ByteStreamer &BS, const MachineLocation &MLoc,
425 bool Indirect) const;
427 //===------------------------------------------------------------------===//
428 // Dwarf Lowering Routines
429 //===------------------------------------------------------------------===//
431 /// \brief Emit frame instruction to describe the layout of the frame.
432 void emitCFIInstruction(const MCCFIInstruction &Inst) const;
434 //===------------------------------------------------------------------===//
435 // Inline Asm Support
436 //===------------------------------------------------------------------===//
438 // These are hooks that targets can override to implement inline asm
439 // support. These should probably be moved out of AsmPrinter someday.
441 /// Print information related to the specified machine instr that is
442 /// independent of the operand, and may be independent of the instr itself.
443 /// This can be useful for portably encoding the comment character or other
444 /// bits of target-specific knowledge into the asmstrings. The syntax used is
445 /// ${:comment}. Targets can override this to add support for their own
447 virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
448 const char *Code) const;
450 /// Print the specified operand of MI, an INLINEASM instruction, using the
451 /// specified assembler variant. Targets should override this to format as
452 /// appropriate. This method can return true if the operand is erroneous.
453 virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
454 unsigned AsmVariant, const char *ExtraCode,
457 /// Print the specified operand of MI, an INLINEASM instruction, using the
458 /// specified assembler variant as an address. Targets should override this to
459 /// format as appropriate. This method can return true if the operand is
461 virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
462 unsigned AsmVariant, const char *ExtraCode,
465 /// Let the target do anything it needs to do after emitting inlineasm.
466 /// This callback can be used restore the original mode in case the
467 /// inlineasm contains directives to switch modes.
468 /// \p StartInfo - the original subtarget info before inline asm
469 /// \p EndInfo - the final subtarget info after parsing the inline asm,
470 /// or NULL if the value is unknown.
471 virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
472 const MCSubtargetInfo *EndInfo) const;
475 /// Private state for PrintSpecial()
476 // Assign a unique ID to this machine instruction.
477 mutable const MachineInstr *LastMI;
478 mutable unsigned LastFn;
479 mutable unsigned Counter;
480 mutable unsigned SetCounter;
482 /// Emit a blob of inline asm to the output streamer.
484 EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = nullptr,
485 InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
487 /// This method formats and emits the specified machine instruction that is an
489 void EmitInlineAsm(const MachineInstr *MI) const;
491 //===------------------------------------------------------------------===//
492 // Internal Implementation Details
493 //===------------------------------------------------------------------===//
495 /// This emits visibility information about symbol, if this is suported by the
497 void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
498 bool IsDefinition = true) const;
500 void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
502 void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
503 const MachineBasicBlock *MBB, unsigned uid) const;
504 void EmitLLVMUsedList(const ConstantArray *InitList);
505 /// Emit llvm.ident metadata in an '.ident' directive.
506 void EmitModuleIdents(Module &M);
507 void EmitXXStructorList(const Constant *List, bool isCtor);
508 GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C);