MCAsmStreamer.cpp revision 8cb9a3b13f3226b7e741768b69d26ecd6b5231f1 
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/ADT/SmallString.h"
12#include "llvm/MC/MCAsmInfo.h"
13#include "llvm/MC/MCCodeEmitter.h"
14#include "llvm/MC/MCContext.h"
15#include "llvm/MC/MCExpr.h"
16#include "llvm/MC/MCInst.h"
17#include "llvm/MC/MCInstPrinter.h"
18#include "llvm/MC/MCSectionMachO.h"
19#include "llvm/MC/MCSymbol.h"
20#include "llvm/Support/ErrorHandling.h"
21#include "llvm/Support/MathExtras.h"
22#include "llvm/Support/Format.h"
23#include "llvm/Support/raw_ostream.h"
24using namespace llvm;
25
26namespace {
27
28class MCAsmStreamer : public MCStreamer {
29  raw_ostream &OS;
30  const MCAsmInfo &MAI;
31  MCInstPrinter *InstPrinter;
32  MCCodeEmitter *Emitter;
33public:
34  MCAsmStreamer(MCContext &Context, raw_ostream &_OS, const MCAsmInfo &tai,
35                MCInstPrinter *_Printer, MCCodeEmitter *_Emitter)
36    : MCStreamer(Context), OS(_OS), MAI(tai), InstPrinter(_Printer),
37      Emitter(_Emitter) {}
38  ~MCAsmStreamer() {}
39
40  /// @name MCStreamer Interface
41  /// @{
42
43  virtual void SwitchSection(const MCSection *Section);
44
45  virtual void EmitLabel(MCSymbol *Symbol);
46
47  virtual void EmitAssemblerFlag(AssemblerFlag Flag);
48
49  virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
50
51  virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
52
53  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
54
55  virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
56                                unsigned ByteAlignment);
57
58  virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
59                            unsigned Size = 0, unsigned ByteAlignment = 0);
60
61  virtual void EmitBytes(StringRef Data);
62
63  virtual void EmitValue(const MCExpr *Value, unsigned Size);
64
65  virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
66                                    unsigned ValueSize = 1,
67                                    unsigned MaxBytesToEmit = 0);
68
69  virtual void EmitValueToOffset(const MCExpr *Offset,
70                                 unsigned char Value = 0);
71
72  virtual void EmitInstruction(const MCInst &Inst);
73
74  virtual void Finish();
75
76  /// @}
77};
78
79} // end anonymous namespace.
80
81static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
82  assert(Bytes && "Invalid size!");
83  return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
84}
85
86static inline const MCExpr *truncateToSize(const MCExpr *Value,
87                                           unsigned Bytes) {
88  // FIXME: Do we really need this routine?
89  return Value;
90}
91
92void MCAsmStreamer::SwitchSection(const MCSection *Section) {
93  assert(Section && "Cannot switch to a null section!");
94  if (Section != CurSection) {
95    CurSection = Section;
96    Section->PrintSwitchToSection(MAI, OS);
97  }
98}
99
100void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
101  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
102  assert(CurSection && "Cannot emit before setting section!");
103
104  OS << *Symbol << ":\n";
105  Symbol->setSection(*CurSection);
106}
107
108void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
109  switch (Flag) {
110  default: assert(0 && "Invalid flag!");
111  case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
112  }
113  OS << '\n';
114}
115
116void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
117  // Only absolute symbols can be redefined.
118  assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
119         "Cannot define a symbol twice!");
120
121  OS << *Symbol << " = " << *Value << '\n';
122
123  // FIXME: Lift context changes into super class.
124  // FIXME: Set associated section.
125  Symbol->setValue(Value);
126}
127
128void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
129                                        SymbolAttr Attribute) {
130  switch (Attribute) {
131  case Global:         OS << ".globl";           break;
132  case Hidden:         OS << ".hidden";          break;
133  case IndirectSymbol: OS << ".indirect_symbol"; break;
134  case Internal:       OS << ".internal";        break;
135  case LazyReference:  OS << ".lazy_reference";  break;
136  case NoDeadStrip:    OS << ".no_dead_strip";   break;
137  case PrivateExtern:  OS << ".private_extern";  break;
138  case Protected:      OS << ".protected";       break;
139  case Reference:      OS << ".reference";       break;
140  case Weak:           OS << ".weak";            break;
141  case WeakDefinition: OS << ".weak_definition"; break;
142  case WeakReference:  OS << ".weak_reference";  break;
143  }
144
145  OS << ' ' << *Symbol << '\n';
146}
147
148void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
149  OS << ".desc" << ' ' << *Symbol << ',' << DescValue << '\n';
150}
151
152void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
153                                     unsigned ByteAlignment) {
154  OS << ".comm " << *Symbol << ',' << Size;
155  if (ByteAlignment != 0)
156    OS << ',' << Log2_32(ByteAlignment);
157  OS << '\n';
158}
159
160void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
161                                 unsigned Size, unsigned ByteAlignment) {
162  // Note: a .zerofill directive does not switch sections.
163  OS << ".zerofill ";
164
165  // This is a mach-o specific directive.
166  const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
167  OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
168
169  if (Symbol != NULL) {
170    OS << ',' << *Symbol << ',' << Size;
171    if (ByteAlignment != 0)
172      OS << ',' << Log2_32(ByteAlignment);
173  }
174  OS << '\n';
175}
176
177void MCAsmStreamer::EmitBytes(StringRef Data) {
178  assert(CurSection && "Cannot emit contents before setting section!");
179  for (unsigned i = 0, e = Data.size(); i != e; ++i)
180    OS << ".byte " << (unsigned) (unsigned char) Data[i] << '\n';
181}
182
183void MCAsmStreamer::EmitValue(const MCExpr *Value, unsigned Size) {
184  assert(CurSection && "Cannot emit contents before setting section!");
185  // Need target hooks to know how to print this.
186  switch (Size) {
187  default:
188    llvm_unreachable("Invalid size for machine code value!");
189  case 1: OS << ".byte"; break;
190  case 2: OS << ".short"; break;
191  case 4: OS << ".long"; break;
192  case 8: OS << ".quad"; break;
193  }
194
195  OS << ' ' << *truncateToSize(Value, Size) << '\n';
196}
197
198void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
199                                         unsigned ValueSize,
200                                         unsigned MaxBytesToEmit) {
201  // Some assemblers don't support non-power of two alignments, so we always
202  // emit alignments as a power of two if possible.
203  if (isPowerOf2_32(ByteAlignment)) {
204    switch (ValueSize) {
205    default: llvm_unreachable("Invalid size for machine code value!");
206    case 1: OS << MAI.getAlignDirective(); break;
207    // FIXME: use MAI for this!
208    case 2: OS << ".p2alignw "; break;
209    case 4: OS << ".p2alignl "; break;
210    case 8: llvm_unreachable("Unsupported alignment size!");
211    }
212
213    if (MAI.getAlignmentIsInBytes())
214      OS << ByteAlignment;
215    else
216      OS << Log2_32(ByteAlignment);
217
218    if (Value || MaxBytesToEmit) {
219      OS << ", 0x";
220      OS.write_hex(truncateToSize(Value, ValueSize));
221
222      if (MaxBytesToEmit)
223        OS << ", " << MaxBytesToEmit;
224    }
225    OS << '\n';
226    return;
227  }
228
229  // Non-power of two alignment.  This is not widely supported by assemblers.
230  // FIXME: Parameterize this based on MAI.
231  switch (ValueSize) {
232  default: llvm_unreachable("Invalid size for machine code value!");
233  case 1: OS << ".balign";  break;
234  case 2: OS << ".balignw"; break;
235  case 4: OS << ".balignl"; break;
236  case 8: llvm_unreachable("Unsupported alignment size!");
237  }
238
239  OS << ' ' << ByteAlignment;
240  OS << ", " << truncateToSize(Value, ValueSize);
241  if (MaxBytesToEmit)
242    OS << ", " << MaxBytesToEmit;
243  OS << '\n';
244}
245
246void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
247                                      unsigned char Value) {
248  // FIXME: Verify that Offset is associated with the current section.
249  OS << ".org " << *Offset << ", " << (unsigned) Value << '\n';
250}
251
252void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
253  assert(CurSection && "Cannot emit contents before setting section!");
254
255  // If we have an AsmPrinter, use that to print.
256  if (InstPrinter) {
257    InstPrinter->printInst(&Inst);
258    OS << '\n';
259
260    // Show the encoding if we have a code emitter.
261    if (Emitter) {
262      SmallString<256> Code;
263      raw_svector_ostream VecOS(Code);
264      Emitter->EncodeInstruction(Inst, VecOS);
265      VecOS.flush();
266
267      OS.indent(20);
268      OS << " # encoding: [";
269      for (unsigned i = 0, e = Code.size(); i != e; ++i) {
270        if (i)
271          OS << ',';
272        OS << format("%#04x", uint8_t(Code[i]));
273      }
274      OS << "]\n";
275    }
276
277    return;
278  }
279
280  // Otherwise fall back to a structural printing for now. Eventually we should
281  // always have access to the target specific printer.
282  Inst.print(OS, &MAI);
283  OS << '\n';
284}
285
286void MCAsmStreamer::Finish() {
287  OS.flush();
288}
289
290MCStreamer *llvm::createAsmStreamer(MCContext &Context, raw_ostream &OS,
291                                    const MCAsmInfo &MAI, MCInstPrinter *IP,
292                                    MCCodeEmitter *CE) {
293  return new MCAsmStreamer(Context, OS, MAI, IP, CE);
294}
295