MCAsmStreamer.cpp revision 6e579c67272afdbca273ad6e6e93c5f6c0f10eeb 
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->getSection() == 0 && "Cannot emit a symbol twice!");
111  assert(CurSection && "Cannot emit before setting section!");
112  assert(!getContext().GetSymbolValue(Symbol) &&
113         "Cannot emit symbol which was directly assigned to!");
114
115  OS << Symbol << ":\n";
116  Symbol->setSection(CurSection);
117  Symbol->setExternal(false);
118}
119
120void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
121  switch (Flag) {
122  default: assert(0 && "Invalid flag!");
123  case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
124  }
125  OS << '\n';
126}
127
128void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
129                                   bool MakeAbsolute) {
130  assert(!Symbol->getSection() && "Cannot assign to a label!");
131
132  if (MakeAbsolute) {
133    OS << ".set " << Symbol << ", " << Value << '\n';
134
135    // HACK: If the value isn't already absolute, set the symbol value to
136    // itself, we want to use the .set absolute value, not the actual
137    // expression.
138    if (!Value.isAbsolute())
139      getContext().SetSymbolValue(Symbol, MCValue::get(Symbol));
140    else
141      getContext().SetSymbolValue(Symbol, Value);
142  } else {
143    OS << Symbol << " = " << Value << '\n';
144    getContext().SetSymbolValue(Symbol, Value);
145  }
146}
147
148void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
149                                        SymbolAttr Attribute) {
150  switch (Attribute) {
151  case Global: OS << ".globl"; break;
152  case Hidden: OS << ".hidden"; break;
153  case IndirectSymbol: OS << ".indirect_symbol"; break;
154  case Internal: OS << ".internal"; break;
155  case LazyReference: OS << ".lazy_reference"; break;
156  case NoDeadStrip: OS << ".no_dead_strip"; break;
157  case PrivateExtern: OS << ".private_extern"; break;
158  case Protected: OS << ".protected"; break;
159  case Reference: OS << ".reference"; break;
160  case Weak: OS << ".weak"; break;
161  case WeakDefinition: OS << ".weak_definition"; break;
162  case WeakReference: OS << ".weak_reference"; break;
163  }
164
165  OS << ' ' << Symbol << '\n';
166}
167
168void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
169  OS << ".desc" << ' ' << Symbol << ',' << DescValue << '\n';
170}
171
172void MCAsmStreamer::EmitLocalSymbol(MCSymbol *Symbol, const MCValue &Value) {
173  OS << ".lsym" << ' ' << Symbol << ',' << Value << '\n';
174}
175
176void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
177                                     unsigned Pow2Alignment, bool IsLocal) {
178  if (IsLocal)
179    OS << ".lcomm";
180  else
181    OS << ".comm";
182  OS << ' ' << Symbol << ',' << Size;
183  if (Pow2Alignment != 0)
184    OS << ',' << Pow2Alignment;
185  OS << '\n';
186}
187
188void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
189                                 unsigned Size, unsigned Pow2Alignment) {
190  // Note: a .zerofill directive does not switch sections.
191  OS << ".zerofill ";
192
193  // This is a mach-o specific directive.
194  const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
195  OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
196
197  if (Symbol != NULL) {
198    OS << ',' << Symbol << ',' << Size;
199    if (Pow2Alignment != 0)
200      OS << ',' << Pow2Alignment;
201  }
202  OS << '\n';
203}
204
205void MCAsmStreamer::EmitBytes(const StringRef &Data) {
206  assert(CurSection && "Cannot emit contents before setting section!");
207  for (unsigned i = 0, e = Data.size(); i != e; ++i)
208    OS << ".byte " << (unsigned) (unsigned char) Data[i] << '\n';
209}
210
211void MCAsmStreamer::EmitValue(const MCValue &Value, unsigned Size) {
212  assert(CurSection && "Cannot emit contents before setting section!");
213  // Need target hooks to know how to print this.
214  switch (Size) {
215  default:
216    llvm_unreachable("Invalid size for machine code value!");
217  case 1: OS << ".byte"; break;
218  case 2: OS << ".short"; break;
219  case 4: OS << ".long"; break;
220  case 8: OS << ".quad"; break;
221  }
222
223  OS << ' ' << truncateToSize(Value, Size) << '\n';
224}
225
226void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
227                                         unsigned ValueSize,
228                                         unsigned MaxBytesToEmit) {
229  // Some assemblers don't support non-power of two alignments, so we always
230  // emit alignments as a power of two if possible.
231  if (isPowerOf2_32(ByteAlignment)) {
232    switch (ValueSize) {
233    default: llvm_unreachable("Invalid size for machine code value!");
234    case 1: OS << TAI.getAlignDirective(); break;
235    // FIXME: use TAI for this!
236    case 2: OS << ".p2alignw "; break;
237    case 4: OS << ".p2alignl "; break;
238    case 8: llvm_unreachable("Unsupported alignment size!");
239    }
240
241    if (TAI.getAlignmentIsInBytes())
242      OS << ByteAlignment;
243    else
244      OS << Log2_32(ByteAlignment);
245
246    if (Value || MaxBytesToEmit) {
247      OS << ", " << truncateToSize(Value, ValueSize);
248
249      if (MaxBytesToEmit)
250        OS << ", " << MaxBytesToEmit;
251    }
252    OS << '\n';
253    return;
254  }
255
256  // Non-power of two alignment.  This is not widely supported by assemblers.
257  // FIXME: Parameterize this based on TAI.
258  switch (ValueSize) {
259  default: llvm_unreachable("Invalid size for machine code value!");
260  case 1: OS << ".balign";  break;
261  case 2: OS << ".balignw"; break;
262  case 4: OS << ".balignl"; break;
263  case 8: llvm_unreachable("Unsupported alignment size!");
264  }
265
266  OS << ' ' << ByteAlignment;
267  OS << ", " << truncateToSize(Value, ValueSize);
268  if (MaxBytesToEmit)
269    OS << ", " << MaxBytesToEmit;
270  OS << '\n';
271}
272
273void MCAsmStreamer::EmitValueToOffset(const MCValue &Offset,
274                                      unsigned char Value) {
275  // FIXME: Verify that Offset is associated with the current section.
276  OS << ".org " << Offset << ", " << (unsigned) Value << '\n';
277}
278
279static raw_ostream &operator<<(raw_ostream &OS, const MCOperand &Op) {
280  if (Op.isReg())
281    return OS << "reg:" << Op.getReg();
282  if (Op.isImm())
283    return OS << "imm:" << Op.getImm();
284  if (Op.isMBBLabel())
285    return OS << "mbblabel:("
286              << Op.getMBBLabelFunction() << ", " << Op.getMBBLabelBlock();
287  assert(Op.isMCValue() && "Invalid operand!");
288  return OS << "val:" << Op.getMCValue();
289}
290
291void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
292  assert(CurSection && "Cannot emit contents before setting section!");
293
294  // If we have an AsmPrinter, use that to print.
295  if (Printer) {
296    Printer->printMCInst(&Inst);
297    return;
298  }
299
300  // Otherwise fall back to a structural printing for now. Eventually we should
301  // always have access to the target specific printer.
302  OS << "MCInst("
303     << "opcode=" << Inst.getOpcode() << ", "
304     << "operands=[";
305  for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
306    if (i)
307      OS << ", ";
308    OS << Inst.getOperand(i);
309  }
310  OS << "])\n";
311}
312
313void MCAsmStreamer::Finish() {
314  OS.flush();
315}
316
317MCStreamer *llvm::createAsmStreamer(MCContext &Context, raw_ostream &OS,
318                                    const TargetAsmInfo &TAI, AsmPrinter *AP) {
319  return new MCAsmStreamer(Context, OS, TAI, AP);
320}
321