llvm.org GIT mirror llvm / cf0db29 include / llvm / CodeGen / AsmPrinter.h
cf0db29

Tree @cf0db29 (Download .tar.gz)

AsmPrinter.h @cf0db29raw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
//===-- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a class to be used as the base class for target specific
// asm writers.  This class primarily handles common functionality used by
// all asm writers.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_ASMPRINTER_H
#define LLVM_CODEGEN_ASMPRINTER_H

#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/DwarfStringPoolEntry.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ErrorHandling.h"

namespace llvm {
class AsmPrinterHandler;
class BlockAddress;
class ByteStreamer;
class GCStrategy;
class Constant;
class ConstantArray;
class DIE;
class DIEAbbrev;
class GCMetadataPrinter;
class GlobalValue;
class GlobalVariable;
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MachineLocation;
class MachineLoopInfo;
class MachineLoop;
class MachineConstantPoolValue;
class MachineJumpTableInfo;
class MachineModuleInfo;
class MCAsmInfo;
class MCCFIInstruction;
class MCContext;
class MCExpr;
class MCInst;
class MCSection;
class MCStreamer;
class MCSubtargetInfo;
class MCSymbol;
class MCTargetOptions;
class MDNode;
class DwarfDebug;
class Mangler;
class TargetLoweringObjectFile;
class DataLayout;
class TargetMachine;

/// This class is intended to be used as a driving class for all asm writers.
class AsmPrinter : public MachineFunctionPass {
public:
  /// Target machine description.
  ///
  TargetMachine &TM;

  /// Target Asm Printer information.
  ///
  const MCAsmInfo *MAI;

  /// This is the context for the output file that we are streaming. This owns
  /// all of the global MC-related objects for the generated translation unit.
  MCContext &OutContext;

  /// This is the MCStreamer object for the file we are generating. This
  /// contains the transient state for the current translation unit that we are
  /// generating (such as the current section etc).
  std::unique_ptr<MCStreamer> OutStreamer;

  /// The current machine function.
  const MachineFunction *MF;

  /// This is a pointer to the current MachineModuleInfo.
  MachineModuleInfo *MMI;

  /// Name-mangler for global names.
  ///
  Mangler *Mang;

  /// The symbol for the current function. This is recalculated at the beginning
  /// of each call to runOnMachineFunction().
  ///
  MCSymbol *CurrentFnSym;

  /// The symbol used to represent the start of the current function for the
  /// purpose of calculating its size (e.g. using the .size directive). By
  /// default, this is equal to CurrentFnSym.
  MCSymbol *CurrentFnSymForSize;

  /// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of
  /// its number of uses by other globals.
  typedef std::pair<const GlobalVariable *, unsigned> GOTEquivUsePair;
  MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs;

private:
  MCSymbol *CurrentFnBegin;
  MCSymbol *CurrentFnEnd;
  MCSymbol *CurExceptionSym;

  // The garbage collection metadata printer table.
  void *GCMetadataPrinters; // Really a DenseMap.

  /// Emit comments in assembly output if this is true.
  ///
  bool VerboseAsm;
  static char ID;

  /// If VerboseAsm is set, a pointer to the loop info for this function.
  MachineLoopInfo *LI;

  struct HandlerInfo {
    AsmPrinterHandler *Handler;
    const char *TimerName, *TimerGroupName;
    HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName,
                const char *TimerGroupName)
        : Handler(Handler), TimerName(TimerName),
          TimerGroupName(TimerGroupName) {}
  };
  /// A vector of all debug/EH info emitters we should use. This vector
  /// maintains ownership of the emitters.
  SmallVector<HandlerInfo, 1> Handlers;

  /// If the target supports dwarf debug info, this pointer is non-null.
  DwarfDebug *DD;

protected:
  explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);

public:
  ~AsmPrinter() override;

  DwarfDebug *getDwarfDebug() { return DD; }
  DwarfDebug *getDwarfDebug() const { return DD; }

  /// Return true if assembly output should contain comments.
  ///
  bool isVerbose() const { return VerboseAsm; }

  /// Return a unique ID for the current function.
  ///
  unsigned getFunctionNumber() const;

  MCSymbol *getFunctionBegin() const { return CurrentFnBegin; }
  MCSymbol *getFunctionEnd() const { return CurrentFnEnd; }
  MCSymbol *getCurExceptionSym();

  /// Return information about object file lowering.
  const TargetLoweringObjectFile &getObjFileLowering() const;

  /// Return information about data layout.
  const DataLayout &getDataLayout() const;

  /// Return information about subtarget.
  const MCSubtargetInfo &getSubtargetInfo() const;

  void EmitToStreamer(MCStreamer &S, const MCInst &Inst);

  /// Return the target triple string.
  StringRef getTargetTriple() const;

  /// Return the current section we are emitting to.
  const MCSection *getCurrentSection() const;

  void getNameWithPrefix(SmallVectorImpl<char> &Name,
                         const GlobalValue *GV) const;

  MCSymbol *getSymbol(const GlobalValue *GV) const;

  //===------------------------------------------------------------------===//
  // MachineFunctionPass Implementation.
  //===------------------------------------------------------------------===//

  /// Record analysis usage.
  ///
  void getAnalysisUsage(AnalysisUsage &AU) const override;

  /// Set up the AsmPrinter when we are working on a new module. If your pass
  /// overrides this, it must make sure to explicitly call this implementation.
  bool doInitialization(Module &M) override;

  /// Shut down the asmprinter. If you override this in your pass, you must make
  /// sure to call it explicitly.
  bool doFinalization(Module &M) override;

  /// Emit the specified function out to the OutStreamer.
  bool runOnMachineFunction(MachineFunction &MF) override {
    SetupMachineFunction(MF);
    EmitFunctionBody();
    return false;
  }

  //===------------------------------------------------------------------===//
  // Coarse grained IR lowering routines.
  //===------------------------------------------------------------------===//

  /// This should be called when a new MachineFunction is being processed from
  /// runOnMachineFunction.
  void SetupMachineFunction(MachineFunction &MF);

  /// This method emits the body and trailer for a function.
  void EmitFunctionBody();

  void emitCFIInstruction(const MachineInstr &MI);

  void emitFrameAlloc(const MachineInstr &MI);

  enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
  CFIMoveType needsCFIMoves();

  bool needsSEHMoves();

  /// Print to the current output stream assembly representations of the
  /// constants in the constant pool MCP. This is used to print out constants
  /// which have been "spilled to memory" by the code generator.
  ///
  virtual void EmitConstantPool();

  /// Print assembly representations of the jump tables used by the current
  /// function to the current output stream.
  ///
  void EmitJumpTableInfo();

  /// Emit the specified global variable to the .s file.
  virtual void EmitGlobalVariable(const GlobalVariable *GV);

  /// Check to see if the specified global is a special global used by LLVM. If
  /// so, emit it and return true, otherwise do nothing and return false.
  bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);

  /// Emit an alignment directive to the specified power of two boundary. For
  /// example, if you pass in 3 here, you will get an 8 byte alignment. If a
  /// global value is specified, and if that global has an explicit alignment
  /// requested, it will override the alignment request if required for
  /// correctness.
  ///
  void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const;

  /// Lower the specified LLVM Constant to an MCExpr.
  const MCExpr *lowerConstant(const Constant *CV);

  /// \brief Print a general LLVM constant to the .s file.
  void EmitGlobalConstant(const Constant *CV);

  /// \brief Unnamed constant global variables solely contaning a pointer to
  /// another globals variable act like a global variable "proxy", or GOT
  /// equivalents, i.e., it's only used to hold the address of the latter. One
  /// optimization is to replace accesses to these proxies by using the GOT
  /// entry for the final global instead. Hence, we select GOT equivalent
  /// candidates among all the module global variables, avoid emitting them
  /// unnecessarily and finally replace references to them by pc relative
  /// accesses to GOT entries.
  void computeGlobalGOTEquivs(Module &M);

  /// \brief Constant expressions using GOT equivalent globals may not be
  /// eligible for PC relative GOT entry conversion, in such cases we need to
  /// emit the proxies we previously omitted in EmitGlobalVariable.
  void emitGlobalGOTEquivs();

  //===------------------------------------------------------------------===//
  // Overridable Hooks
  //===------------------------------------------------------------------===//

  // Targets can, or in the case of EmitInstruction, must implement these to
  // customize output.

  /// This virtual method can be overridden by targets that want to emit
  /// something at the start of their file.
  virtual void EmitStartOfAsmFile(Module &) {}

  /// This virtual method can be overridden by targets that want to emit
  /// something at the end of their file.
  virtual void EmitEndOfAsmFile(Module &) {}

  /// Targets can override this to emit stuff before the first basic block in
  /// the function.
  virtual void EmitFunctionBodyStart() {}

  /// Targets can override this to emit stuff after the last basic block in the
  /// function.
  virtual void EmitFunctionBodyEnd() {}

  /// Targets can override this to emit stuff at the start of a basic block.
  /// By default, this method prints the label for the specified
  /// MachineBasicBlock, an alignment (if present) and a comment describing it
  /// if appropriate.
  virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;

  /// Targets can override this to emit stuff at the end of a basic block.
  virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB) {}

  /// Targets should implement this to emit instructions.
  virtual void EmitInstruction(const MachineInstr *) {
    llvm_unreachable("EmitInstruction not implemented");
  }

  /// Return the symbol for the specified constant pool entry.
  virtual MCSymbol *GetCPISymbol(unsigned CPID) const;

  virtual void EmitFunctionEntryLabel();

  virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);

  /// Targets can override this to change how global constants that are part of
  /// a C++ static/global constructor list are emitted.
  virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }

  /// Return true if the basic block has exactly one predecessor and the control
  /// transfer mechanism between the predecessor and this block is a
  /// fall-through.
  virtual bool
  isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;

  /// Targets can override this to customize the output of IMPLICIT_DEF
  /// instructions in verbose mode.
  virtual void emitImplicitDef(const MachineInstr *MI) const;

  //===------------------------------------------------------------------===//
  // Symbol Lowering Routines.
  //===------------------------------------------------------------------===//
public:
  MCSymbol *createTempSymbol(const Twine &Name) const;

  /// Return the MCSymbol for a private symbol with global value name as its
  /// base, with the specified suffix.
  MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
                                         StringRef Suffix) const;

  /// Return the MCSymbol for the specified ExternalSymbol.
  MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;

  /// Return the symbol for the specified jump table entry.
  MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;

  /// Return the symbol for the specified jump table .set
  /// FIXME: privatize to AsmPrinter.
  MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;

  /// Return the MCSymbol used to satisfy BlockAddress uses of the specified
  /// basic block.
  MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
  MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;

  //===------------------------------------------------------------------===//
  // Emission Helper Routines.
  //===------------------------------------------------------------------===//
public:
  /// This is just convenient handler for printing offsets.
  void printOffset(int64_t Offset, raw_ostream &OS) const;

  /// Emit a byte directive and value.
  ///
  void EmitInt8(int Value) const;

  /// Emit a short directive and value.
  ///
  void EmitInt16(int Value) const;

  /// Emit a long directive and value.
  ///
  void EmitInt32(int Value) const;

  /// Emit something like ".long Hi-Lo" where the size in bytes of the directive
  /// is specified by Size and Hi/Lo specify the labels.  This implicitly uses
  /// .set if it is available.
  void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
                           unsigned Size) const;

  /// Emit something like ".long Label+Offset" where the size in bytes of the
  /// directive is specified by Size and Label specifies the label.  This
  /// implicitly uses .set if it is available.
  void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
                           unsigned Size, bool IsSectionRelative = false) const;

  /// Emit something like ".long Label" where the size in bytes of the directive
  /// is specified by Size and Label specifies the label.
  void EmitLabelReference(const MCSymbol *Label, unsigned Size,
                          bool IsSectionRelative = false) const {
    EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
  }

  //===------------------------------------------------------------------===//
  // Dwarf Emission Helper Routines
  //===------------------------------------------------------------------===//

  /// Emit the specified signed leb128 value.
  void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;

  /// Emit the specified unsigned leb128 value.
  void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
                   unsigned PadTo = 0) const;

  /// Emit a .byte 42 directive for a DW_CFA_xxx value.
  void EmitCFAByte(unsigned Val) const;

  /// Emit a .byte 42 directive that corresponds to an encoding.  If verbose
  /// assembly output is enabled, we output comments describing the encoding.
  /// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
  void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;

  /// Return the size of the encoding in bytes.
  unsigned GetSizeOfEncodedValue(unsigned Encoding) const;

  /// Emit reference to a ttype global with a specified encoding.
  void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;

  /// Emit a reference to a symbol for use in dwarf. Different object formats
  /// represent this in different ways. Some use a relocation others encode
  /// the label offset in its section.
  void emitDwarfSymbolReference(const MCSymbol *Label,
                                bool ForceOffset = false) const;

  /// Emit the 4-byte offset of a string from the start of its section.
  ///
  /// When possible, emit a DwarfStringPool section offset without any
  /// relocations, and without using the symbol.  Otherwise, defers to \a
  /// emitDwarfSymbolReference().
  void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const;

  /// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
  virtual unsigned getISAEncoding() { return 0; }

  /// EmitDwarfRegOp - Emit a dwarf register operation.
  virtual void EmitDwarfRegOp(ByteStreamer &BS,
                              const MachineLocation &MLoc) const;

  //===------------------------------------------------------------------===//
  // Dwarf Lowering Routines
  //===------------------------------------------------------------------===//

  /// \brief Emit frame instruction to describe the layout of the frame.
  void emitCFIInstruction(const MCCFIInstruction &Inst) const;

  /// \brief Emit Dwarf abbreviation table.
  void emitDwarfAbbrevs(const std::vector<DIEAbbrev *>& Abbrevs) const;

  /// \brief Recursively emit Dwarf DIE tree.
  void emitDwarfDIE(const DIE &Die) const;

  //===------------------------------------------------------------------===//
  // Inline Asm Support
  //===------------------------------------------------------------------===//
public:
  // These are hooks that targets can override to implement inline asm
  // support.  These should probably be moved out of AsmPrinter someday.

  /// Print information related to the specified machine instr that is
  /// independent of the operand, and may be independent of the instr itself.
  /// This can be useful for portably encoding the comment character or other
  /// bits of target-specific knowledge into the asmstrings.  The syntax used is
  /// ${:comment}.  Targets can override this to add support for their own
  /// strange codes.
  virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
                            const char *Code) const;

  /// Print the specified operand of MI, an INLINEASM instruction, using the
  /// specified assembler variant.  Targets should override this to format as
  /// appropriate.  This method can return true if the operand is erroneous.
  virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                               unsigned AsmVariant, const char *ExtraCode,
                               raw_ostream &OS);

  /// Print the specified operand of MI, an INLINEASM instruction, using the
  /// specified assembler variant as an address. Targets should override this to
  /// format as appropriate.  This method can return true if the operand is
  /// erroneous.
  virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                                     unsigned AsmVariant, const char *ExtraCode,
                                     raw_ostream &OS);

  /// Let the target do anything it needs to do before emitting inlineasm.
  /// \p StartInfo - the subtarget info before parsing inline asm
  virtual void emitInlineAsmStart() const;

  /// Let the target do anything it needs to do after emitting inlineasm.
  /// This callback can be used restore the original mode in case the
  /// inlineasm contains directives to switch modes.
  /// \p StartInfo - the original subtarget info before inline asm
  /// \p EndInfo   - the final subtarget info after parsing the inline asm,
  ///                or NULL if the value is unknown.
  virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
                                const MCSubtargetInfo *EndInfo) const;

private:
  /// Private state for PrintSpecial()
  // Assign a unique ID to this machine instruction.
  mutable const MachineInstr *LastMI;
  mutable unsigned LastFn;
  mutable unsigned Counter;

  /// This method emits the header for the current function.
  virtual void EmitFunctionHeader();

  /// Emit a blob of inline asm to the output streamer.
  void
  EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
                const MCTargetOptions &MCOptions,
                const MDNode *LocMDNode = nullptr,
                InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;

  /// This method formats and emits the specified machine instruction that is an
  /// inline asm.
  void EmitInlineAsm(const MachineInstr *MI) const;

  //===------------------------------------------------------------------===//
  // Internal Implementation Details
  //===------------------------------------------------------------------===//

  /// This emits visibility information about symbol, if this is suported by the
  /// target.
  void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
                      bool IsDefinition = true) const;

  void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;

  void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
                          const MachineBasicBlock *MBB, unsigned uid) const;
  void EmitLLVMUsedList(const ConstantArray *InitList);
  /// Emit llvm.ident metadata in an '.ident' directive.
  void EmitModuleIdents(Module &M);
  void EmitXXStructorList(const Constant *List, bool isCtor);
  GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C);
};
} // namespace llvm

#endif