MCAsmStreamer.cpp revision d79d9dce47d505369662ae5111dba24f9ccdef68 
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  /// @name MCStreamer Interface
77  /// @{
78
79  virtual void SwitchSection(const MCSection *Section);
80
81  virtual void EmitLabel(MCSymbol *Symbol);
82
83  virtual void EmitAssemblerFlag(AssemblerFlag Flag);
84
85  virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
86
87  virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
88
89  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
90
91  virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
92                                unsigned ByteAlignment);
93
94  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
95                            unsigned Size = 0, unsigned ByteAlignment = 0);
96
97  virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
98
99  virtual void EmitValue(const MCExpr *Value, unsigned Size,unsigned AddrSpace);
100  virtual void EmitIntValue(uint64_t Value, unsigned Size, unsigned AddrSpace);
101
102  virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue,
103                        unsigned AddrSpace);
104
105  virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
106                                    unsigned ValueSize = 1,
107                                    unsigned MaxBytesToEmit = 0);
108
109  virtual void EmitValueToOffset(const MCExpr *Offset,
110                                 unsigned char Value = 0);
111
112  virtual void EmitInstruction(const MCInst &Inst);
113
114  virtual void Finish();
115
116  /// @}
117};
118
119} // end anonymous namespace.
120
121/// AddComment - Add a comment that can be emitted to the generated .s
122/// file if applicable as a QoI issue to make the output of the compiler
123/// more readable.  This only affects the MCAsmStreamer, and only when
124/// verbose assembly output is enabled.
125void MCAsmStreamer::AddComment(const Twine &T) {
126  if (!IsVerboseAsm) return;
127
128  // Make sure that CommentStream is flushed.
129  CommentStream.flush();
130
131  T.toVector(CommentToEmit);
132  // Each comment goes on its own line.
133  CommentToEmit.push_back('\n');
134}
135
136void MCAsmStreamer::EmitCommentsAndEOL() {
137  if (CommentToEmit.empty() && CommentStream.GetNumBytesInBuffer() == 0) {
138    OS << '\n';
139    return;
140  }
141
142  CommentStream.flush();
143  StringRef Comments = CommentToEmit.str();
144
145  assert(Comments.back() == '\n' &&
146         "Comment array not newline terminated");
147  do {
148    // Emit a line of comments.
149    OS.PadToColumn(MAI.getCommentColumn());
150    size_t Position = Comments.find('\n');
151    OS << MAI.getCommentString() << ' ' << Comments.substr(0, Position) << '\n';
152
153    Comments = Comments.substr(Position+1);
154  } while (!Comments.empty());
155
156  CommentStream.clear();
157}
158
159
160static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
161  assert(Bytes && "Invalid size!");
162  return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
163}
164
165static inline const MCExpr *truncateToSize(const MCExpr *Value,
166                                           unsigned Bytes) {
167  // FIXME: Do we really need this routine?
168  return Value;
169}
170
171void MCAsmStreamer::SwitchSection(const MCSection *Section) {
172  assert(Section && "Cannot switch to a null section!");
173  if (Section != CurSection) {
174    CurSection = Section;
175    Section->PrintSwitchToSection(MAI, OS);
176  }
177}
178
179void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
180  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
181  assert(CurSection && "Cannot emit before setting section!");
182
183  OS << *Symbol << ":";
184  EmitEOL();
185  Symbol->setSection(*CurSection);
186}
187
188void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
189  switch (Flag) {
190  default: assert(0 && "Invalid flag!");
191  case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
192  }
193  EmitEOL();
194}
195
196void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
197  // Only absolute symbols can be redefined.
198  assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
199         "Cannot define a symbol twice!");
200
201  OS << *Symbol << " = " << *Value;
202  EmitEOL();
203
204  // FIXME: Lift context changes into super class.
205  // FIXME: Set associated section.
206  Symbol->setValue(Value);
207}
208
209void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
210                                        SymbolAttr Attribute) {
211  switch (Attribute) {
212  case Global:         OS << MAI.getGlobalDirective(); break; // .globl
213  case Hidden:         OS << ".hidden ";          break;
214  case IndirectSymbol: OS << ".indirect_symbol "; break;
215  case Internal:       OS << ".internal ";        break;
216  case LazyReference:  OS << ".lazy_reference ";  break;
217  case NoDeadStrip:    OS << ".no_dead_strip ";   break;
218  case PrivateExtern:  OS << ".private_extern ";  break;
219  case Protected:      OS << ".protected ";       break;
220  case Reference:      OS << ".reference ";       break;
221  case Weak:           OS << ".weak ";            break;
222  case WeakDefinition: OS << ".weak_definition "; break;
223  case WeakReference:  OS << ".weak_reference ";  break;
224  }
225
226  OS << *Symbol;
227  EmitEOL();
228}
229
230void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
231  OS << ".desc" << ' ' << *Symbol << ',' << DescValue;
232  EmitEOL();
233}
234
235void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
236                                     unsigned ByteAlignment) {
237  OS << MAI.getCOMMDirective() << *Symbol << ',' << Size;
238  if (ByteAlignment != 0 && MAI.getCOMMDirectiveTakesAlignment()) {
239    if (MAI.getAlignmentIsInBytes())
240      OS << ',' << ByteAlignment;
241    else
242      OS << ',' << Log2_32(ByteAlignment);
243  }
244  EmitEOL();
245}
246
247void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
248                                 unsigned Size, unsigned ByteAlignment) {
249  // Note: a .zerofill directive does not switch sections.
250  OS << ".zerofill ";
251
252  // This is a mach-o specific directive.
253  const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
254  OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
255
256  if (Symbol != NULL) {
257    OS << ',' << *Symbol << ',' << Size;
258    if (ByteAlignment != 0)
259      OS << ',' << Log2_32(ByteAlignment);
260  }
261  EmitEOL();
262}
263
264void MCAsmStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
265  assert(CurSection && "Cannot emit contents before setting section!");
266  const char *Directive = MAI.getData8bitsDirective(AddrSpace);
267  for (unsigned i = 0, e = Data.size(); i != e; ++i) {
268    OS << Directive << (unsigned)(unsigned char)Data[i];
269    EmitEOL();
270  }
271}
272
273/// EmitIntValue - Special case of EmitValue that avoids the client having
274/// to pass in a MCExpr for constant integers.
275void MCAsmStreamer::EmitIntValue(uint64_t Value, unsigned Size,
276                                 unsigned AddrSpace) {
277  assert(CurSection && "Cannot emit contents before setting section!");
278  const char *Directive = 0;
279  switch (Size) {
280  default: break;
281  case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
282  case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
283  case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
284  case 8:
285    Directive = MAI.getData64bitsDirective(AddrSpace);
286    // If the target doesn't support 64-bit data, emit as two 32-bit halves.
287    if (Directive) break;
288    if (isLittleEndian()) {
289      EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
290      EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
291    } else {
292      EmitIntValue((uint32_t)(Value >> 32), 4, AddrSpace);
293      EmitIntValue((uint32_t)(Value >> 0 ), 4, AddrSpace);
294    }
295    return;
296  }
297
298  assert(Directive && "Invalid size for machine code value!");
299  OS << Directive << truncateToSize(Value, Size);
300  EmitEOL();
301}
302
303void MCAsmStreamer::EmitValue(const MCExpr *Value, unsigned Size,
304                              unsigned AddrSpace) {
305  assert(CurSection && "Cannot emit contents before setting section!");
306  const char *Directive = 0;
307  switch (Size) {
308  default: break;
309  case 1: Directive = MAI.getData8bitsDirective(AddrSpace); break;
310  case 2: Directive = MAI.getData16bitsDirective(AddrSpace); break;
311  case 4: Directive = MAI.getData32bitsDirective(AddrSpace); break;
312  case 8: Directive = MAI.getData64bitsDirective(AddrSpace); break;
313  }
314
315  assert(Directive && "Invalid size for machine code value!");
316  OS << Directive << *truncateToSize(Value, Size);
317  EmitEOL();
318}
319
320/// EmitFill - Emit NumBytes bytes worth of the value specified by
321/// FillValue.  This implements directives such as '.space'.
322void MCAsmStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
323                             unsigned AddrSpace) {
324  if (NumBytes == 0) return;
325
326  if (AddrSpace == 0)
327    if (const char *ZeroDirective = MAI.getZeroDirective()) {
328      OS << ZeroDirective << NumBytes;
329      if (FillValue != 0)
330        OS << ',' << (int)FillValue;
331      EmitEOL();
332      return;
333    }
334
335  // Emit a byte at a time.
336  MCStreamer::EmitFill(NumBytes, FillValue, AddrSpace);
337}
338
339void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
340                                         unsigned ValueSize,
341                                         unsigned MaxBytesToEmit) {
342  // Some assemblers don't support non-power of two alignments, so we always
343  // emit alignments as a power of two if possible.
344  if (isPowerOf2_32(ByteAlignment)) {
345    switch (ValueSize) {
346    default: llvm_unreachable("Invalid size for machine code value!");
347    case 1: OS << MAI.getAlignDirective(); break;
348    // FIXME: use MAI for this!
349    case 2: OS << ".p2alignw "; break;
350    case 4: OS << ".p2alignl "; break;
351    case 8: llvm_unreachable("Unsupported alignment size!");
352    }
353
354    if (MAI.getAlignmentIsInBytes())
355      OS << ByteAlignment;
356    else
357      OS << Log2_32(ByteAlignment);
358
359    if (Value || MaxBytesToEmit) {
360      OS << ", 0x";
361      OS.write_hex(truncateToSize(Value, ValueSize));
362
363      if (MaxBytesToEmit)
364        OS << ", " << MaxBytesToEmit;
365    }
366    EmitEOL();
367    return;
368  }
369
370  // Non-power of two alignment.  This is not widely supported by assemblers.
371  // FIXME: Parameterize this based on MAI.
372  switch (ValueSize) {
373  default: llvm_unreachable("Invalid size for machine code value!");
374  case 1: OS << ".balign";  break;
375  case 2: OS << ".balignw"; break;
376  case 4: OS << ".balignl"; break;
377  case 8: llvm_unreachable("Unsupported alignment size!");
378  }
379
380  OS << ' ' << ByteAlignment;
381  OS << ", " << truncateToSize(Value, ValueSize);
382  if (MaxBytesToEmit)
383    OS << ", " << MaxBytesToEmit;
384  EmitEOL();
385}
386
387void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
388                                      unsigned char Value) {
389  // FIXME: Verify that Offset is associated with the current section.
390  OS << ".org " << *Offset << ", " << (unsigned) Value;
391  EmitEOL();
392}
393
394void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
395  assert(CurSection && "Cannot emit contents before setting section!");
396
397  // If we have an AsmPrinter, use that to print.
398  if (InstPrinter) {
399    InstPrinter->printInst(&Inst);
400    EmitEOL();
401
402    // Show the encoding if we have a code emitter.
403    if (Emitter) {
404      SmallString<256> Code;
405      raw_svector_ostream VecOS(Code);
406      Emitter->EncodeInstruction(Inst, VecOS);
407      VecOS.flush();
408
409      OS.indent(20);
410      OS << " # encoding: [";
411      for (unsigned i = 0, e = Code.size(); i != e; ++i) {
412        if (i)
413          OS << ',';
414        OS << format("%#04x", uint8_t(Code[i]));
415      }
416      OS << "]\n";
417    }
418
419    return;
420  }
421
422  // Otherwise fall back to a structural printing for now. Eventually we should
423  // always have access to the target specific printer.
424  Inst.print(OS, &MAI);
425  EmitEOL();
426}
427
428void MCAsmStreamer::Finish() {
429  OS.flush();
430}
431
432MCStreamer *llvm::createAsmStreamer(MCContext &Context,
433                                    formatted_raw_ostream &OS,
434                                    const MCAsmInfo &MAI, bool isLittleEndian,
435                                    bool isVerboseAsm, MCInstPrinter *IP,
436                                    MCCodeEmitter *CE) {
437  return new MCAsmStreamer(Context, OS, MAI, isLittleEndian, isVerboseAsm,
438                           IP, CE);
439}
440