MCAsmStreamer.cpp revision 12e555c36ce11c39ce15cd0b27bf7b02a068beb2 
1//===- lib/MC/MCAsmStreamer.cpp - Text Assembly Output --------------------===//
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#include "llvm/MC/MCStreamer.h"
11#include "llvm/MC/MCAsmInfo.h"
12#include "llvm/MC/MCCodeEmitter.h"
13#include "llvm/MC/MCContext.h"
14#include "llvm/MC/MCExpr.h"
15#include "llvm/MC/MCInst.h"
16#include "llvm/MC/MCInstPrinter.h"
17#include "llvm/MC/MCSectionMachO.h"
18#include "llvm/MC/MCSymbol.h"
19#include "llvm/ADT/SmallString.h"
20#include "llvm/ADT/Twine.h"
21#include "llvm/Support/ErrorHandling.h"
22#include "llvm/Support/MathExtras.h"
23#include "llvm/Support/Format.h"
24#include "llvm/Support/FormattedStream.h"
25using namespace llvm;
26
27namespace {
28
29class MCAsmStreamer : public MCStreamer {
30  formatted_raw_ostream &OS;
31  const MCAsmInfo &MAI;
32  bool IsLittleEndian, IsVerboseAsm;
33  MCInstPrinter *InstPrinter;
34  MCCodeEmitter *Emitter;
35
36  SmallString<128> CommentToEmit;
37  raw_svector_ostream CommentStream;
38public:
39  MCAsmStreamer(MCContext &Context, formatted_raw_ostream &os,
40                const MCAsmInfo &mai,
41                bool isLittleEndian, bool isVerboseAsm, MCInstPrinter *printer,
42                MCCodeEmitter *emitter)
43    : MCStreamer(Context), OS(os), MAI(mai), IsLittleEndian(isLittleEndian),
44      IsVerboseAsm(isVerboseAsm), InstPrinter(printer), Emitter(emitter),
45      CommentStream(CommentToEmit) {}
46  ~MCAsmStreamer() {}
47
48  bool isLittleEndian() const { return IsLittleEndian; }
49
50
51  inline void EmitEOL() {
52    // If we don't have any comments, just emit a \n.
53    if (!IsVerboseAsm) {
54      OS << '\n';
55      return;
56    }
57    EmitCommentsAndEOL();
58  }
59  void EmitCommentsAndEOL();
60
61  /// AddComment - Add a comment that can be emitted to the generated .s
62  /// file if applicable as a QoI issue to make the output of the compiler
63  /// more readable.  This only affects the MCAsmStreamer, and only when
64  /// verbose assembly output is enabled.
65  virtual void AddComment(const Twine &T);
66
67  /// GetCommentOS - Return a raw_ostream that comments can be written to.
68  /// Unlike AddComment, you are required to terminate comments with \n if you
69  /// use this method.
70  virtual raw_ostream &GetCommentOS() {
71    if (!IsVerboseAsm)
72      return nulls();  // Discard comments unless in verbose asm mode.
73    return CommentStream;
74  }
75
76  /// AddBlankLine - Emit a blank line to a .s file to pretty it up.
77  virtual void AddBlankLine() {
78    EmitEOL();
79  }
80
81  /// @name MCStreamer Interface
82  /// @{
83
84  virtual void SwitchSection(const MCSection *Section);
85
86  virtual void EmitLabel(MCSymbol *Symbol);
87
88  virtual void EmitAssemblerFlag(AssemblerFlag Flag);
89
90  virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
91
92  virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
93
94  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
95
96  virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
97                                unsigned ByteAlignment);
98
99  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
100                            unsigned Size = 0, unsigned ByteAlignment = 0);
101
102  virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
103
104  virtual void EmitValue(const MCExpr *Value, unsigned Size,unsigned AddrSpace);
105  virtual void EmitIntValue(uint64_t Value, unsigned Size, unsigned AddrSpace);
106
107  virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
108                        unsigned AddrSpace);
109
110  virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
111                                    unsigned ValueSize = 1,
112                                    unsigned MaxBytesToEmit = 0);
113
114  virtual void EmitValueToOffset(const MCExpr *Offset,
115                                 unsigned char Value = 0);
116
117  virtual void EmitInstruction(const MCInst &Inst);
118
119  virtual void Finish();
120
121  /// @}
122};
123
124} // end anonymous namespace.
125
126/// AddComment - Add a comment that can be emitted to the generated .s
127/// file if applicable as a QoI issue to make the output of the compiler
128/// more readable.  This only affects the MCAsmStreamer, and only when
129/// verbose assembly output is enabled.
130void MCAsmStreamer::AddComment(const Twine &T) {
131  if (!IsVerboseAsm) return;
132
133  // Make sure that CommentStream is flushed.
134  CommentStream.flush();
135
136  T.toVector(CommentToEmit);
137  // Each comment goes on its own line.
138  CommentToEmit.push_back('\n');
139
140  // Tell the comment stream that the vector changed underneath it.
141  CommentStream.resync();
142}
143
144void MCAsmStreamer::EmitCommentsAndEOL() {
145  if (CommentToEmit.empty() && CommentStream.GetNumBytesInBuffer() == 0) {
146    OS << '\n';
147    return;
148  }
149
150  CommentStream.flush();
151  StringRef Comments = CommentToEmit.str();
152
153  assert(Comments.back() == '\n' &&
154         "Comment array not newline terminated");
155  do {
156    // Emit a line of comments.
157    OS.PadToColumn(MAI.getCommentColumn());
158    size_t Position = Comments.find('\n');
159    OS << MAI.getCommentString() << ' ' << Comments.substr(0, Position) << '\n';
160
161    Comments = Comments.substr(Position+1);
162  } while (!Comments.empty());
163
164  CommentToEmit.clear();
165  // Tell the comment stream that the vector changed underneath it.
166  CommentStream.resync();
167}
168
169
170static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
171  assert(Bytes && "Invalid size!");
172  return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
173}
174
175static inline const MCExpr *truncateToSize(const MCExpr *Value,
176                                           unsigned Bytes) {
177  // FIXME: Do we really need this routine?
178  return Value;
179}
180
181void MCAsmStreamer::SwitchSection(const MCSection *Section) {
182  assert(Section && "Cannot switch to a null section!");
183  if (Section != CurSection) {
184    CurSection = Section;
185    Section->PrintSwitchToSection(MAI, OS);
186  }
187}
188
189void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
190  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
191  assert(CurSection && "Cannot emit before setting section!");
192
193  OS << *Symbol << ":";
194  EmitEOL();
195  Symbol->setSection(*CurSection);
196}
197
198void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
199  switch (Flag) {
200  default: assert(0 && "Invalid flag!");
201  case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
202  }
203  EmitEOL();
204}
205
206void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
207  // Only absolute symbols can be redefined.
208  assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
209         "Cannot define a symbol twice!");
210
211  OS << *Symbol << " = " << *Value;
212  EmitEOL();
213
214  // FIXME: Lift context changes into super class.
215  // FIXME: Set associated section.
216  Symbol->setValue(Value);
217}
218
219void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
220                                        SymbolAttr Attribute) {
221  switch (Attribute) {
222  case Global:         OS << MAI.getGlobalDirective(); break; // .globl
223  case Hidden:         OS << ".hidden ";          break;
224  case IndirectSymbol: OS << ".indirect_symbol "; break;
225  case Internal:       OS << ".internal ";        break;
226  case LazyReference:  OS << ".lazy_reference ";  break;
227  case NoDeadStrip:    OS << ".no_dead_strip ";   break;
228  case PrivateExtern:  OS << ".private_extern ";  break;
229  case Protected:      OS << ".protected ";       break;
230  case Reference:      OS << ".reference ";       break;
231  case Weak:           OS << ".weak ";            break;
232  case WeakDefinition: OS << ".weak_definition "; break;
233  case WeakReference:  OS << ".weak_reference ";  break;
234  }
235
236  OS << *Symbol;
237  EmitEOL();
238}
239
240void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
241  OS << ".desc" << ' ' << *Symbol << ',' << DescValue;
242  EmitEOL();
243}
244
245void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
246                                     unsigned ByteAlignment) {
247  OS << MAI.getCOMMDirective() << *Symbol << ',' << Size;
248  if (ByteAlignment != 0 && MAI.getCOMMDirectiveTakesAlignment()) {
249    if (MAI.getAlignmentIsInBytes())
250      OS << ',' << ByteAlignment;
251    else
252      OS << ',' << Log2_32(ByteAlignment);
253  }
254  EmitEOL();
255}
256
257void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
258                                 unsigned Size, unsigned ByteAlignment) {
259  // Note: a .zerofill directive does not switch sections.
260  OS << ".zerofill ";
261
262  // This is a mach-o specific directive.
263  const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
264  OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
265
266  if (Symbol != NULL) {
267    OS << ',' << *Symbol << ',' << Size;
268    if (ByteAlignment != 0)
269      OS << ',' << Log2_32(ByteAlignment);
270  }
271  EmitEOL();
272}
273
274static inline char toOctal(int X) { return (X&7)+'0'; }
275
276void MCAsmStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
277  assert(CurSection && "Cannot emit contents before setting section!");
278  if (Data.empty()) return;
279
280  if (Data.size() == 1) {
281    OS << MAI.getData8bitsDirective(AddrSpace);
282    OS << (unsigned)(unsigned char)Data[0];
283    EmitEOL();
284    return;
285  }
286
287  // If the data ends with 0 and the target supports .asciz, use it, otherwise
288  // use .ascii
289  if (MAI.getAscizDirective() && Data.back() == 0) {
290    OS << MAI.getAscizDirective();
291    Data = Data.substr(0, Data.size()-1);
292  } else {
293    OS << MAI.getAsciiDirective();
294  }
295
296  OS << " \"";
297  for (unsigned i = 0, e = Data.size(); i != e; ++i) {
298    unsigned char C = Data[i];
299    if (C == '"' || C == '\\') {
300      OS << '\\' << (char)C;
301      continue;
302    }
303
304    if (isprint((unsigned char)C)) {
305      OS << (char)C;
306      continue;
307    }
308
309    switch (C) {
310    case '\b': OS << "\\b"; break;
311    case '\f': OS << "\\f"; break;
312    case '\n': OS << "\\n"; break;
313    case '\r': OS << "\\r"; break;
314    case '\t': OS << "\\t"; break;
315    default:
316      OS << '\\';
317      OS << toOctal(C >> 6);
318      OS << toOctal(C >> 3);
319      OS << toOctal(C >> 0);
320      break;
321    }
322  }
323  OS << '"';
324  EmitEOL();
325}
326
327/// EmitIntValue - Special case of EmitValue that avoids the client having
328/// to pass in a MCExpr for constant integers.
329void MCAsmStreamer::EmitIntValue(uint64_t Value, unsigned Size,
330                                 unsigned AddrSpace) {
331  assert(CurSection && "Cannot emit contents before setting section!");
332  const char *Directive = 0;
333  switch (Size) {
334  default: break;
335  case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
336  case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
337  case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
338  case 8:
339    Directive = MAI.getData64bitsDirective(AddrSpace);
340    // If the target doesn't support 64-bit data, emit as two 32-bit halves.
341    if (Directive) break;
342    if (isLittleEndian()) {
343      EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
344      EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
345    } else {
346      EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
347      EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
348    }
349    return;
350  }
351
352  assert(Directive && "Invalid size for machine code value!");
353  OS << Directive << truncateToSize(Value, Size);
354  EmitEOL();
355}
356
357void MCAsmStreamer::EmitValue(const MCExpr *Value, unsigned Size,
358                              unsigned AddrSpace) {
359  assert(CurSection && "Cannot emit contents before setting section!");
360  const char *Directive = 0;
361  switch (Size) {
362  default: break;
363  case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
364  case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
365  case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
366  case 8: Directive = MAI.getData64bitsDirective(AddrSpace); break;
367  }
368
369  assert(Directive && "Invalid size for machine code value!");
370  OS << Directive << *truncateToSize(Value, Size);
371  EmitEOL();
372}
373
374/// EmitFill - Emit NumBytes bytes worth of the value specified by
375/// FillValue.  This implements directives such as '.space'.
376void MCAsmStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
377                             unsigned AddrSpace) {
378  if (NumBytes == 0) return;
379
380  if (AddrSpace == 0)
381    if (const char *ZeroDirective = MAI.getZeroDirective()) {
382      OS << ZeroDirective << NumBytes;
383      if (FillValue != 0)
384        OS << ',' << (int)FillValue;
385      EmitEOL();
386      return;
387    }
388
389  // Emit a byte at a time.
390  MCStreamer::EmitFill(NumBytes, FillValue, AddrSpace);
391}
392
393void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
394                                         unsigned ValueSize,
395                                         unsigned MaxBytesToEmit) {
396  // Some assemblers don't support non-power of two alignments, so we always
397  // emit alignments as a power of two if possible.
398  if (isPowerOf2_32(ByteAlignment)) {
399    switch (ValueSize) {
400    default: llvm_unreachable("Invalid size for machine code value!");
401    case 1: OS << MAI.getAlignDirective(); break;
402    // FIXME: use MAI for this!
403    case 2: OS << ".p2alignw "; break;
404    case 4: OS << ".p2alignl "; break;
405    case 8: llvm_unreachable("Unsupported alignment size!");
406    }
407
408    if (MAI.getAlignmentIsInBytes())
409      OS << ByteAlignment;
410    else
411      OS << Log2_32(ByteAlignment);
412
413    if (Value || MaxBytesToEmit) {
414      OS << ", 0x";
415      OS.write_hex(truncateToSize(Value, ValueSize));
416
417      if (MaxBytesToEmit)
418        OS << ", " << MaxBytesToEmit;
419    }
420    EmitEOL();
421    return;
422  }
423
424  // Non-power of two alignment.  This is not widely supported by assemblers.
425  // FIXME: Parameterize this based on MAI.
426  switch (ValueSize) {
427  default: llvm_unreachable("Invalid size for machine code value!");
428  case 1: OS << ".balign";  break;
429  case 2: OS << ".balignw"; break;
430  case 4: OS << ".balignl"; break;
431  case 8: llvm_unreachable("Unsupported alignment size!");
432  }
433
434  OS << ' ' << ByteAlignment;
435  OS << ", " << truncateToSize(Value, ValueSize);
436  if (MaxBytesToEmit)
437    OS << ", " << MaxBytesToEmit;
438  EmitEOL();
439}
440
441void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
442                                      unsigned char Value) {
443  // FIXME: Verify that Offset is associated with the current section.
444  OS << ".org " << *Offset << ", " << (unsigned) Value;
445  EmitEOL();
446}
447
448void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
449  assert(CurSection && "Cannot emit contents before setting section!");
450
451  // If we have an AsmPrinter, use that to print.
452  if (InstPrinter) {
453    InstPrinter->printInst(&Inst);
454    EmitEOL();
455
456    // Show the encoding if we have a code emitter.
457    if (Emitter) {
458      SmallString<256> Code;
459      raw_svector_ostream VecOS(Code);
460      Emitter->EncodeInstruction(Inst, VecOS);
461      VecOS.flush();
462
463      OS.indent(20);
464      OS << " # encoding: [";
465      for (unsigned i = 0, e = Code.size(); i != e; ++i) {
466        if (i)
467          OS << ',';
468        OS << format("%#04x", uint8_t(Code[i]));
469      }
470      OS << "]\n";
471    }
472
473    return;
474  }
475
476  // Otherwise fall back to a structural printing for now. Eventually we should
477  // always have access to the target specific printer.
478  Inst.print(OS, &MAI);
479  EmitEOL();
480}
481
482void MCAsmStreamer::Finish() {
483  OS.flush();
484}
485
486MCStreamer *llvm::createAsmStreamer(MCContext &Context,
487                                    formatted_raw_ostream &OS,
488                                    const MCAsmInfo &MAI, bool isLittleEndian,
489                                    bool isVerboseAsm, MCInstPrinter *IP,
490                                    MCCodeEmitter *CE) {
491  return new MCAsmStreamer(Context, OS, MAI, isLittleEndian, isVerboseAsm,
492                           IP, CE);
493}
494