MCAsmStreamer.cpp revision 8906ff1b9dfde28f1ff00706643ca10843b26e01 
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/CodeGen/AsmPrinter.h"
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCInst.h"
14#include "llvm/MC/MCSectionMachO.h"
15#include "llvm/MC/MCSymbol.h"
16#include "llvm/MC/MCValue.h"
17#include "llvm/Target/TargetAsmInfo.h"
18#include "llvm/Support/ErrorHandling.h"
19#include "llvm/Support/MathExtras.h"
20#include "llvm/Support/raw_ostream.h"
21using namespace llvm;
22
23namespace {
24
25class MCAsmStreamer : public MCStreamer {
26  raw_ostream &OS;
27  const TargetAsmInfo &TAI;
28  AsmPrinter *Printer;
29public:
30  MCAsmStreamer(MCContext &Context, raw_ostream &_OS, const TargetAsmInfo &tai,
31                AsmPrinter *_AsmPrinter)
32    : MCStreamer(Context), OS(_OS), TAI(tai), Printer(_AsmPrinter) {}
33  ~MCAsmStreamer() {}
34
35  /// @name MCStreamer Interface
36  /// @{
37
38  virtual void SwitchSection(const MCSection *Section);
39
40  virtual void EmitLabel(MCSymbol *Symbol);
41
42  virtual void EmitAssemblerFlag(AssemblerFlag Flag);
43
44  virtual void EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
45                              bool MakeAbsolute = false);
46
47  virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
48
49  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
50
51  virtual void EmitLocalSymbol(MCSymbol *Symbol, const MCValue &Value);
52
53  virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
54                                unsigned Pow2Alignment, bool IsLocal);
55
56  virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
57                            unsigned Size = 0, unsigned Pow2Alignment = 0);
58
59  virtual void EmitBytes(const StringRef &Data);
60
61  virtual void EmitValue(const MCValue &Value, unsigned Size);
62
63  virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
64                                    unsigned ValueSize = 1,
65                                    unsigned MaxBytesToEmit = 0);
66
67  virtual void EmitValueToOffset(const MCValue &Offset,
68                                 unsigned char Value = 0);
69
70  virtual void EmitInstruction(const MCInst &Inst);
71
72  virtual void Finish();
73
74  /// @}
75};
76
77} // end anonymous namespace.
78
79/// Allow printing symbols directly to a raw_ostream with proper quoting.
80static inline raw_ostream &operator<<(raw_ostream &os, const MCSymbol *S) {
81  S->print(os);
82  return os;
83}
84
85/// Allow printing values directly to a raw_ostream.
86static inline raw_ostream &operator<<(raw_ostream &os, const MCValue &Value) {
87  Value.print(os);
88  return os;
89}
90
91static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
92  assert(Bytes && "Invalid size!");
93  return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
94}
95
96static inline MCValue truncateToSize(const MCValue &Value, unsigned Bytes) {
97  return MCValue::get(Value.getSymA(), Value.getSymB(),
98                      truncateToSize(Value.getConstant(), Bytes));
99}
100
101void MCAsmStreamer::SwitchSection(const MCSection *Section) {
102  assert(Section && "Cannot switch to a null section!");
103  if (Section != CurSection) {
104    CurSection = Section;
105    Section->PrintSwitchToSection(TAI, OS);
106  }
107}
108
109void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
110  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
111  assert(CurSection && "Cannot emit before setting section!");
112
113  OS << Symbol << ":\n";
114  Symbol->setSection(*CurSection);
115}
116
117void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
118  switch (Flag) {
119  default: assert(0 && "Invalid flag!");
120  case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
121  }
122  OS << '\n';
123}
124
125void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
126                                   bool MakeAbsolute) {
127  // Only absolute symbols can be redefined.
128  assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
129         "Cannot define a symbol twice!");
130
131  if (MakeAbsolute) {
132    OS << ".set " << Symbol << ", " << Value << '\n';
133
134    // HACK: If the value isn't already absolute, set the symbol value to
135    // itself, we want to use the .set absolute value, not the actual
136    // expression.
137    if (!Value.isAbsolute())
138      getContext().SetSymbolValue(Symbol, MCValue::get(Symbol));
139    else
140      getContext().SetSymbolValue(Symbol, Value);
141  } else {
142    OS << Symbol << " = " << Value << '\n';
143    getContext().SetSymbolValue(Symbol, Value);
144  }
145}
146
147void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
148                                        SymbolAttr Attribute) {
149  switch (Attribute) {
150  case Global: OS << ".globl"; break;
151  case Hidden: OS << ".hidden"; break;
152  case IndirectSymbol: OS << ".indirect_symbol"; break;
153  case Internal: OS << ".internal"; break;
154  case LazyReference: OS << ".lazy_reference"; break;
155  case NoDeadStrip: OS << ".no_dead_strip"; break;
156  case PrivateExtern: OS << ".private_extern"; break;
157  case Protected: OS << ".protected"; break;
158  case Reference: OS << ".reference"; break;
159  case Weak: OS << ".weak"; break;
160  case WeakDefinition: OS << ".weak_definition"; break;
161  case WeakReference: OS << ".weak_reference"; break;
162  }
163
164  OS << ' ' << Symbol << '\n';
165}
166
167void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
168  OS << ".desc" << ' ' << Symbol << ',' << DescValue << '\n';
169}
170
171void MCAsmStreamer::EmitLocalSymbol(MCSymbol *Symbol, const MCValue &Value) {
172  OS << ".lsym" << ' ' << Symbol << ',' << Value << '\n';
173}
174
175void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
176                                     unsigned Pow2Alignment, bool IsLocal) {
177  if (IsLocal)
178    OS << ".lcomm";
179  else
180    OS << ".comm";
181  OS << ' ' << Symbol << ',' << Size;
182  if (Pow2Alignment != 0)
183    OS << ',' << Pow2Alignment;
184  OS << '\n';
185}
186
187void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
188                                 unsigned Size, unsigned Pow2Alignment) {
189  // Note: a .zerofill directive does not switch sections.
190  OS << ".zerofill ";
191
192  // This is a mach-o specific directive.
193  const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
194  OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
195
196  if (Symbol != NULL) {
197    OS << ',' << Symbol << ',' << Size;
198    if (Pow2Alignment != 0)
199      OS << ',' << Pow2Alignment;
200  }
201  OS << '\n';
202}
203
204void MCAsmStreamer::EmitBytes(const StringRef &Data) {
205  assert(CurSection && "Cannot emit contents before setting section!");
206  for (unsigned i = 0, e = Data.size(); i != e; ++i)
207    OS << ".byte " << (unsigned) (unsigned char) Data[i] << '\n';
208}
209
210void MCAsmStreamer::EmitValue(const MCValue &Value, unsigned Size) {
211  assert(CurSection && "Cannot emit contents before setting section!");
212  // Need target hooks to know how to print this.
213  switch (Size) {
214  default:
215    llvm_unreachable("Invalid size for machine code value!");
216  case 1: OS << ".byte"; break;
217  case 2: OS << ".short"; break;
218  case 4: OS << ".long"; break;
219  case 8: OS << ".quad"; break;
220  }
221
222  OS << ' ' << truncateToSize(Value, Size) << '\n';
223}
224
225void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
226                                         unsigned ValueSize,
227                                         unsigned MaxBytesToEmit) {
228  // Some assemblers don't support non-power of two alignments, so we always
229  // emit alignments as a power of two if possible.
230  if (isPowerOf2_32(ByteAlignment)) {
231    switch (ValueSize) {
232    default: llvm_unreachable("Invalid size for machine code value!");
233    case 1: OS << TAI.getAlignDirective(); break;
234    // FIXME: use TAI for this!
235    case 2: OS << ".p2alignw "; break;
236    case 4: OS << ".p2alignl "; break;
237    case 8: llvm_unreachable("Unsupported alignment size!");
238    }
239
240    if (TAI.getAlignmentIsInBytes())
241      OS << ByteAlignment;
242    else
243      OS << Log2_32(ByteAlignment);
244
245    if (Value || MaxBytesToEmit) {
246      OS << ", " << truncateToSize(Value, ValueSize);
247
248      if (MaxBytesToEmit)
249        OS << ", " << MaxBytesToEmit;
250    }
251    OS << '\n';
252    return;
253  }
254
255  // Non-power of two alignment.  This is not widely supported by assemblers.
256  // FIXME: Parameterize this based on TAI.
257  switch (ValueSize) {
258  default: llvm_unreachable("Invalid size for machine code value!");
259  case 1: OS << ".balign";  break;
260  case 2: OS << ".balignw"; break;
261  case 4: OS << ".balignl"; break;
262  case 8: llvm_unreachable("Unsupported alignment size!");
263  }
264
265  OS << ' ' << ByteAlignment;
266  OS << ", " << truncateToSize(Value, ValueSize);
267  if (MaxBytesToEmit)
268    OS << ", " << MaxBytesToEmit;
269  OS << '\n';
270}
271
272void MCAsmStreamer::EmitValueToOffset(const MCValue &Offset,
273                                      unsigned char Value) {
274  // FIXME: Verify that Offset is associated with the current section.
275  OS << ".org " << Offset << ", " << (unsigned) Value << '\n';
276}
277
278static raw_ostream &operator<<(raw_ostream &OS, const MCOperand &Op) {
279  if (Op.isReg())
280    return OS << "reg:" << Op.getReg();
281  if (Op.isImm())
282    return OS << "imm:" << Op.getImm();
283  if (Op.isMBBLabel())
284    return OS << "mbblabel:("
285              << Op.getMBBLabelFunction() << ", " << Op.getMBBLabelBlock();
286  assert(Op.isMCValue() && "Invalid operand!");
287  return OS << "val:" << Op.getMCValue();
288}
289
290void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
291  assert(CurSection && "Cannot emit contents before setting section!");
292
293  // If we have an AsmPrinter, use that to print.
294  if (Printer) {
295    Printer->printMCInst(&Inst);
296    return;
297  }
298
299  // Otherwise fall back to a structural printing for now. Eventually we should
300  // always have access to the target specific printer.
301  OS << "MCInst("
302     << "opcode=" << Inst.getOpcode() << ", "
303     << "operands=[";
304  for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
305    if (i)
306      OS << ", ";
307    OS << Inst.getOperand(i);
308  }
309  OS << "])\n";
310}
311
312void MCAsmStreamer::Finish() {
313  OS.flush();
314}
315
316MCStreamer *llvm::createAsmStreamer(MCContext &Context, raw_ostream &OS,
317                                    const TargetAsmInfo &TAI, AsmPrinter *AP) {
318  return new MCAsmStreamer(Context, OS, TAI, AP);
319}
320