MCAsmStreamer.cpp revision 9a7e2ccf574368b60455f8c8975030475a1f3ce0 
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
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCInst.h"
14#include "llvm/MC/MCSection.h"
15#include "llvm/MC/MCSymbol.h"
16#include "llvm/MC/MCValue.h"
17#include "llvm/Support/ErrorHandling.h"
18#include "llvm/Support/raw_ostream.h"
19
20using namespace llvm;
21
22namespace {
23
24  class MCAsmStreamer : public MCStreamer {
25    raw_ostream &OS;
26
27    MCSection *CurSection;
28
29  public:
30    MCAsmStreamer(MCContext &Context, raw_ostream &_OS)
31      : MCStreamer(Context), OS(_OS), CurSection(0) {}
32    ~MCAsmStreamer() {}
33
34    /// @name MCStreamer Interface
35    /// @{
36
37    virtual void SwitchSection(MCSection *Section);
38
39    virtual void EmitLabel(MCSymbol *Symbol);
40
41    virtual void EmitAssemblerFlag(AssemblerFlag Flag);
42
43    virtual void EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
44                                bool MakeAbsolute = false);
45
46    virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
47
48    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
49
50    virtual void EmitLocalSymbol(MCSymbol *Symbol, const MCValue &Value);
51
52    virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
53                                  unsigned Pow2Alignment, bool IsLocal);
54
55    virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
56                              unsigned Size = 0, unsigned Pow2Alignment = 0);
57
58    virtual void AbortAssembly(const char *AbortReason = NULL);
59
60    virtual void EmitBytes(const StringRef &Data);
61
62    virtual void EmitValue(const MCValue &Value, unsigned Size);
63
64    virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
65                                      unsigned ValueSize = 1,
66                                      unsigned MaxBytesToEmit = 0);
67
68    virtual void EmitValueToOffset(const MCValue &Offset,
69                                   unsigned char Value = 0);
70
71    virtual void EmitInstruction(const MCInst &Inst);
72
73    virtual void Finish();
74
75    /// @}
76  };
77
78}
79
80/// Allow printing values directly to a raw_ostream.
81static inline raw_ostream &operator<<(raw_ostream &os, const MCValue &Value) {
82  if (Value.getSymA()) {
83    os << Value.getSymA()->getName();
84    if (Value.getSymB())
85      os << " - " << Value.getSymB()->getName();
86    if (Value.getConstant())
87      os << " + " << Value.getConstant();
88  } else {
89    assert(!Value.getSymB() && "Invalid machine code value!");
90    os << Value.getConstant();
91  }
92
93  return os;
94}
95
96static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
97  assert(Bytes && "Invalid size!");
98  return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
99}
100
101static inline MCValue truncateToSize(const MCValue &Value, unsigned Bytes) {
102  return MCValue::get(Value.getSymA(), Value.getSymB(),
103                      truncateToSize(Value.getConstant(), Bytes));
104}
105
106void MCAsmStreamer::SwitchSection(MCSection *Section) {
107  if (Section != CurSection) {
108    CurSection = Section;
109
110    // FIXME: Really we would like the segment, flags, etc. to be separate
111    // values instead of embedded in the name. Not all assemblers understand all
112    // this stuff though.
113    OS << ".section " << Section->getName() << "\n";
114  }
115}
116
117void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
118  assert(Symbol->getSection() == 0 && "Cannot emit a symbol twice!");
119  assert(CurSection && "Cannot emit before setting section!");
120  assert(!getContext().GetSymbolValue(Symbol) &&
121         "Cannot emit symbol which was directly assigned to!");
122
123  OS << Symbol->getName() << ":\n";
124  Symbol->setSection(CurSection);
125  Symbol->setExternal(false);
126}
127
128void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
129  switch (Flag) {
130  case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
131  }
132  OS << '\n';
133}
134
135void MCAsmStreamer::AbortAssembly(const char *AbortReason) {
136  OS << ".abort";
137  if (AbortReason != NULL)
138    OS << ' ' << AbortReason;
139  OS << '\n';
140
141}
142
143void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
144                                   bool MakeAbsolute) {
145  assert(!Symbol->getSection() && "Cannot assign to a label!");
146
147  if (MakeAbsolute) {
148    OS << ".set " << Symbol->getName() << ", " << Value << '\n';
149  } else {
150    OS << Symbol->getName() << " = " << Value << '\n';
151  }
152
153  getContext().SetSymbolValue(Symbol, Value);
154}
155
156void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
157                                        SymbolAttr Attribute) {
158  switch (Attribute) {
159  case Global: OS << ".globl"; break;
160  case Hidden: OS << ".hidden"; break;
161  case IndirectSymbol: OS << ".indirect_symbol"; break;
162  case Internal: OS << ".internal"; break;
163  case LazyReference: OS << ".lazy_reference"; break;
164  case NoDeadStrip: OS << ".no_dead_strip"; break;
165  case PrivateExtern: OS << ".private_extern"; break;
166  case Protected: OS << ".protected"; break;
167  case Reference: OS << ".reference"; break;
168  case Weak: OS << ".weak"; break;
169  case WeakDefinition: OS << ".weak_definition"; break;
170  case WeakReference: OS << ".weak_reference"; break;
171  }
172
173  OS << ' ' << Symbol->getName() << '\n';
174}
175
176void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
177  OS << ".desc" << ' ' << Symbol->getName() << ',' << DescValue << '\n';
178}
179
180void MCAsmStreamer::EmitLocalSymbol(MCSymbol *Symbol, const MCValue &Value) {
181  OS << ".lsym" << ' ' << Symbol->getName() << ',' << Value << '\n';
182}
183
184void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
185                                     unsigned Pow2Alignment, bool IsLocal) {
186  if (IsLocal)
187    OS << ".lcomm";
188  else
189    OS << ".comm";
190  OS << ' ' << Symbol->getName() << ',' << Size;
191  if (Pow2Alignment != 0)
192    OS << ',' << Pow2Alignment;
193  OS << '\n';
194}
195
196void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
197                                 unsigned Size, unsigned Pow2Alignment) {
198  // Note: a .zerofill directive does not switch sections
199  // FIXME: Really we would like the segment and section names as well as the
200  // section type to be separate values instead of embedded in the name. Not
201  // all assemblers understand all this stuff though.
202  OS << ".zerofill " << Section->getName();
203  if (Symbol != NULL) {
204    OS << ',' << Symbol->getName() << ',' << Size;
205    if (Pow2Alignment != 0)
206      OS << ',' << Pow2Alignment;
207  }
208  OS << '\n';
209}
210
211void MCAsmStreamer::EmitBytes(const StringRef &Data) {
212  assert(CurSection && "Cannot emit contents before setting section!");
213  for (unsigned i = 0, e = Data.size(); i != e; ++i)
214    OS << ".byte " << (unsigned) Data[i] << '\n';
215}
216
217void MCAsmStreamer::EmitValue(const MCValue &Value, unsigned Size) {
218  assert(CurSection && "Cannot emit contents before setting section!");
219  // Need target hooks to know how to print this.
220  switch (Size) {
221  default:
222    llvm_unreachable("Invalid size for machine code value!");
223  case 1: OS << ".byte"; break;
224  case 2: OS << ".short"; break;
225  case 4: OS << ".long"; break;
226  case 8: OS << ".quad"; break;
227  }
228
229  OS << ' ' << truncateToSize(Value, Size) << '\n';
230}
231
232void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
233                                         unsigned ValueSize,
234                                         unsigned MaxBytesToEmit) {
235  // Some assemblers don't support .balign, so we always emit as .p2align if
236  // this is a power of two. Otherwise we assume the client knows the target
237  // supports .balign and use that.
238  unsigned Pow2 = Log2_32(ByteAlignment);
239  bool IsPow2 = (1U << Pow2) == ByteAlignment;
240
241  switch (ValueSize) {
242  default:
243    llvm_unreachable("Invalid size for machine code value!");
244  case 8:
245    llvm_unreachable("Unsupported alignment size!");
246  case 1: OS << (IsPow2 ? ".p2align" : ".balign"); break;
247  case 2: OS << (IsPow2 ? ".p2alignw" : ".balignw"); break;
248  case 4: OS << (IsPow2 ? ".p2alignl" : ".balignl"); break;
249  }
250
251  OS << ' ' << (IsPow2 ? Pow2 : ByteAlignment);
252
253  OS << ", " << truncateToSize(Value, ValueSize);
254  if (MaxBytesToEmit)
255    OS << ", " << MaxBytesToEmit;
256  OS << '\n';
257}
258
259void MCAsmStreamer::EmitValueToOffset(const MCValue &Offset,
260                                      unsigned char Value) {
261  // FIXME: Verify that Offset is associated with the current section.
262  OS << ".org " << Offset << ", " << (unsigned) Value << '\n';
263}
264
265static raw_ostream &operator<<(raw_ostream &OS, const MCOperand &Op) {
266  if (Op.isReg())
267    return OS << "reg:" << Op.getReg();
268  if (Op.isImm())
269    return OS << "imm:" << Op.getImm();
270  if (Op.isMBBLabel())
271    return OS << "mbblabel:("
272              << Op.getMBBLabelFunction() << ", " << Op.getMBBLabelBlock();
273  assert(Op.isMCValue() && "Invalid operand!");
274  return OS << "val:" << Op.getMCValue();
275}
276
277void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
278  assert(CurSection && "Cannot emit contents before setting section!");
279  // FIXME: Implement proper printing.
280  OS << "MCInst("
281     << "opcode=" << Inst.getOpcode() << ", "
282     << "operands=[";
283  for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
284    if (i)
285      OS << ", ";
286    OS << Inst.getOperand(i);
287  }
288  OS << "])\n";
289}
290
291void MCAsmStreamer::Finish() {
292  OS.flush();
293}
294
295MCStreamer *llvm::createAsmStreamer(MCContext &Context, raw_ostream &OS) {
296  return new MCAsmStreamer(Context, OS);
297}
298