1//===-- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework --------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
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
12// all asm writers.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CODEGEN_ASMPRINTER_H
17#define LLVM_CODEGEN_ASMPRINTER_H
18
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"
24
25namespace llvm {
26class AsmPrinterHandler;
27class BlockAddress;
28class ByteStreamer;
29class GCStrategy;
30class Constant;
31class ConstantArray;
32class GCMetadataPrinter;
33class GlobalValue;
34class GlobalVariable;
35class MachineBasicBlock;
36class MachineFunction;
37class MachineInstr;
38class MachineLocation;
39class MachineLoopInfo;
40class MachineLoop;
41class MachineConstantPoolValue;
42class MachineJumpTableInfo;
43class MachineModuleInfo;
44class MCAsmInfo;
45class MCCFIInstruction;
46class MCContext;
47class MCInst;
48class MCInstrInfo;
49class MCSection;
50class MCStreamer;
51class MCSubtargetInfo;
52class MCSymbol;
53class MDNode;
54class DwarfDebug;
55class Mangler;
56class TargetLoweringObjectFile;
57class DataLayout;
58class TargetMachine;
59
60/// This class is intended to be used as a driving class for all asm writers.
61class AsmPrinter : public MachineFunctionPass {
62public:
63  /// Target machine description.
64  ///
65  TargetMachine &TM;
66
67  /// Target Asm Printer information.
68  ///
69  const MCAsmInfo *MAI;
70
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;
75
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;
80
81  /// The current machine function.
82  const MachineFunction *MF;
83
84  /// This is a pointer to the current MachineModuleInfo.
85  MachineModuleInfo *MMI;
86
87  /// Name-mangler for global names.
88  ///
89  Mangler *Mang;
90
91  /// The symbol for the current function. This is recalculated at the beginning
92  /// of each call to runOnMachineFunction().
93  ///
94  MCSymbol *CurrentFnSym;
95
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;
100
101private:
102  // The garbage collection metadata printer table.
103  void *GCMetadataPrinters; // Really a DenseMap.
104
105  /// Emit comments in assembly output if this is true.
106  ///
107  bool VerboseAsm;
108  static char ID;
109
110  /// If VerboseAsm is set, a pointer to the loop info for this function.
111  MachineLoopInfo *LI;
112
113  struct HandlerInfo {
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) {}
120  };
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;
124
125  /// If the target supports dwarf debug info, this pointer is non-null.
126  DwarfDebug *DD;
127
128protected:
129  explicit AsmPrinter(TargetMachine &TM, MCStreamer &Streamer);
130
131public:
132  virtual ~AsmPrinter();
133
134  DwarfDebug *getDwarfDebug() { return DD; }
135
136  /// Return true if assembly output should contain comments.
137  ///
138  bool isVerbose() const { return VerboseAsm; }
139
140  /// Return a unique ID for the current function.
141  ///
142  unsigned getFunctionNumber() const;
143
144  /// Return information about object file lowering.
145  const TargetLoweringObjectFile &getObjFileLowering() const;
146
147  /// Return information about data layout.
148  const DataLayout &getDataLayout() const;
149
150  /// Return information about subtarget.
151  const MCSubtargetInfo &getSubtargetInfo() const;
152
153  void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
154
155  /// Return the target triple string.
156  StringRef getTargetTriple() const;
157
158  /// Return the current section we are emitting to.
159  const MCSection *getCurrentSection() const;
160
161  void getNameWithPrefix(SmallVectorImpl<char> &Name,
162                         const GlobalValue *GV) const;
163
164  MCSymbol *getSymbol(const GlobalValue *GV) const;
165
166  //===------------------------------------------------------------------===//
167  // MachineFunctionPass Implementation.
168  //===------------------------------------------------------------------===//
169
170  /// Record analysis usage.
171  ///
172  void getAnalysisUsage(AnalysisUsage &AU) const override;
173
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;
177
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;
181
182  /// Emit the specified function out to the OutStreamer.
183  bool runOnMachineFunction(MachineFunction &MF) override {
184    SetupMachineFunction(MF);
185    EmitFunctionHeader();
186    EmitFunctionBody();
187    return false;
188  }
189
190  //===------------------------------------------------------------------===//
191  // Coarse grained IR lowering routines.
192  //===------------------------------------------------------------------===//
193
194  /// This should be called when a new MachineFunction is being processed from
195  /// runOnMachineFunction.
196  void SetupMachineFunction(MachineFunction &MF);
197
198  /// This method emits the header for the current function.
199  void EmitFunctionHeader();
200
201  /// This method emits the body and trailer for a function.
202  void EmitFunctionBody();
203
204  void emitCFIInstruction(const MachineInstr &MI);
205
206  enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
207  CFIMoveType needsCFIMoves();
208
209  bool needsSEHMoves();
210
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.
214  ///
215  virtual void EmitConstantPool();
216
217  /// Print assembly representations of the jump tables used by the current
218  /// function to the current output stream.
219  ///
220  void EmitJumpTableInfo();
221
222  /// Emit the specified global variable to the .s file.
223  virtual void EmitGlobalVariable(const GlobalVariable *GV);
224
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);
228
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
233  /// correctness.
234  ///
235  void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const;
236
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;
240
241  /// \brief Print a general LLVM constant to the .s file.
242  void EmitGlobalConstant(const Constant *CV);
243
244  //===------------------------------------------------------------------===//
245  // Overridable Hooks
246  //===------------------------------------------------------------------===//
247
248  // Targets can, or in the case of EmitInstruction, must implement these to
249  // customize output.
250
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 &) {}
254
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 &) {}
258
259  /// Targets can override this to emit stuff before the first basic block in
260  /// the function.
261  virtual void EmitFunctionBodyStart() {}
262
263  /// Targets can override this to emit stuff after the last basic block in the
264  /// function.
265  virtual void EmitFunctionBodyEnd() {}
266
267  /// Targets should implement this to emit instructions.
268  virtual void EmitInstruction(const MachineInstr *) {
269    llvm_unreachable("EmitInstruction not implemented");
270  }
271
272  /// Return the symbol for the specified constant pool entry.
273  virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
274
275  virtual void EmitFunctionEntryLabel();
276
277  virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
278
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); }
282
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
285  /// fall-through.
286  virtual bool
287  isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
288
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;
292
293  //===------------------------------------------------------------------===//
294  // Symbol Lowering Routines.
295  //===------------------------------------------------------------------===//
296public:
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;
300
301  /// Return an assembler temporary label with the specified stem.
302  MCSymbol *GetTempSymbol(Twine Name) const;
303
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;
308
309  /// Return the MCSymbol for the specified ExternalSymbol.
310  MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
311
312  /// Return the symbol for the specified jump table entry.
313  MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
314
315  /// Return the symbol for the specified jump table .set
316  /// FIXME: privatize to AsmPrinter.
317  MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
318
319  /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
320  /// basic block.
321  MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
322  MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
323
324  //===------------------------------------------------------------------===//
325  // Emission Helper Routines.
326  //===------------------------------------------------------------------===//
327public:
328  /// This is just convenient handler for printing offsets.
329  void printOffset(int64_t Offset, raw_ostream &OS) const;
330
331  /// Emit a byte directive and value.
332  ///
333  void EmitInt8(int Value) const;
334
335  /// Emit a short directive and value.
336  ///
337  void EmitInt16(int Value) const;
338
339  /// Emit a long directive and value.
340  ///
341  void EmitInt32(int Value) const;
342
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;
348
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;
354
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;
360
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);
366  }
367
368  //===------------------------------------------------------------------===//
369  // Dwarf Emission Helper Routines
370  //===------------------------------------------------------------------===//
371
372  /// Emit the specified signed leb128 value.
373  void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
374
375  /// Emit the specified unsigned leb128 value.
376  void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
377                   unsigned PadTo = 0) const;
378
379  /// Emit a .byte 42 directive for a DW_CFA_xxx value.
380  void EmitCFAByte(unsigned Val) const;
381
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;
386
387  /// Return the size of the encoding in bytes.
388  unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
389
390  /// Emit reference to a ttype global with a specified encoding.
391  void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
392
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.
396  ///
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;
401
402  /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
403  virtual unsigned getISAEncoding() { return 0; }
404
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.
410  ///
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;
420
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;
425
426  //===------------------------------------------------------------------===//
427  // Dwarf Lowering Routines
428  //===------------------------------------------------------------------===//
429
430  /// \brief Emit frame instruction to describe the layout of the frame.
431  void emitCFIInstruction(const MCCFIInstruction &Inst) const;
432
433  //===------------------------------------------------------------------===//
434  // Inline Asm Support
435  //===------------------------------------------------------------------===//
436public:
437  // These are hooks that targets can override to implement inline asm
438  // support.  These should probably be moved out of AsmPrinter someday.
439
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
445  /// strange codes.
446  virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
447                            const char *Code) const;
448
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,
454                               raw_ostream &OS);
455
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
459  /// erroneous.
460  virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
461                                     unsigned AsmVariant, const char *ExtraCode,
462                                     raw_ostream &OS);
463
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;
472
473private:
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;
480
481  /// Emit a blob of inline asm to the output streamer.
482  void
483  EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = nullptr,
484                InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
485
486  /// This method formats and emits the specified machine instruction that is an
487  /// inline asm.
488  void EmitInlineAsm(const MachineInstr *MI) const;
489
490  //===------------------------------------------------------------------===//
491  // Internal Implementation Details
492  //===------------------------------------------------------------------===//
493
494  /// This emits visibility information about symbol, if this is suported by the
495  /// target.
496  void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
497                      bool IsDefinition = true) const;
498
499  void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
500
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);
508};
509}
510
511#endif
512