MCAsmStreamer.cpp revision 9be3fee2bdc3126fb87e4e1b31935905f4bcc4d0 
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/raw_ostream.h"
18using namespace llvm;
19
20namespace {
21
22  class MCAsmStreamer : public MCStreamer {
23    raw_ostream &OS;
24
25    MCSection *CurSection;
26
27  public:
28    MCAsmStreamer(MCContext &Context, raw_ostream &_OS)
29      : MCStreamer(Context), OS(_OS), CurSection(0) {}
30    ~MCAsmStreamer() {}
31
32    /// @name MCStreamer Interface
33    /// @{
34
35    virtual void SwitchSection(MCSection *Section);
36
37    virtual void EmitLabel(MCSymbol *Symbol);
38
39    virtual void EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
40                                bool MakeAbsolute = false);
41
42    virtual void EmitSymbolAttribute(MCSymbol *Symbol, SymbolAttr Attribute);
43
44    virtual void EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
45                                  unsigned Pow2Alignment, bool IsLocal);
46
47    virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = NULL,
48                              unsigned Size = 0, unsigned Pow2Alignment = 0);
49
50    virtual void EmitBytes(const char *Data, unsigned Length);
51
52    virtual void EmitValue(const MCValue &Value, unsigned Size);
53
54    virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
55                                      unsigned ValueSize = 1,
56                                      unsigned MaxBytesToEmit = 0);
57
58    virtual void EmitValueToOffset(const MCValue &Offset,
59                                   unsigned char Value = 0);
60
61    virtual void EmitInstruction(const MCInst &Inst);
62
63    virtual void Finish();
64
65    /// @}
66  };
67
68}
69
70/// Allow printing values directly to a raw_ostream.
71static inline raw_ostream &operator<<(raw_ostream &os, const MCValue &Value) {
72  if (Value.getSymA()) {
73    os << Value.getSymA()->getName();
74    if (Value.getSymB())
75      os << " - " << Value.getSymB()->getName();
76    if (Value.getConstant())
77      os << " + " << Value.getConstant();
78  } else {
79    assert(!Value.getSymB() && "Invalid machine code value!");
80    os << Value.getConstant();
81  }
82
83  return os;
84}
85
86static inline int64_t truncateToSize(int64_t Value, unsigned Bytes) {
87  assert(Bytes && "Invalid size!");
88  return Value & ((uint64_t) (int64_t) -1 >> (64 - Bytes * 8));
89}
90
91static inline MCValue truncateToSize(const MCValue &Value, unsigned Bytes) {
92  return MCValue::get(Value.getSymA(), Value.getSymB(),
93                      truncateToSize(Value.getConstant(), Bytes));
94}
95
96void MCAsmStreamer::SwitchSection(MCSection *Section) {
97  if (Section != CurSection) {
98    CurSection = Section;
99
100    // FIXME: Really we would like the segment, flags, etc. to be separate
101    // values instead of embedded in the name. Not all assemblers understand all
102    // this stuff though.
103    OS << ".section " << Section->getName() << "\n";
104  }
105}
106
107void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
108  assert(Symbol->getSection() == 0 && "Cannot emit a symbol twice!");
109  assert(CurSection && "Cannot emit before setting section!");
110  assert(!getContext().GetSymbolValue(Symbol) &&
111         "Cannot emit symbol which was directly assigned to!");
112
113  OS << Symbol->getName() << ":\n";
114  Symbol->setSection(CurSection);
115  Symbol->setExternal(false);
116}
117
118void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
119                                   bool MakeAbsolute) {
120  assert(!Symbol->getSection() && "Cannot assign to a label!");
121
122  if (MakeAbsolute) {
123    OS << ".set " << Symbol->getName() << ", " << Value << '\n';
124  } else {
125    OS << Symbol->getName() << " = " << Value << '\n';
126  }
127
128  getContext().SetSymbolValue(Symbol, Value);
129}
130
131void MCAsmStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
132                                        SymbolAttr Attribute) {
133  switch (Attribute) {
134  case Global: OS << ".globl"; break;
135  case Hidden: OS << ".hidden"; break;
136  case IndirectSymbol: OS << ".indirect_symbol"; break;
137  case Internal: OS << ".internal"; break;
138  case LazyReference: OS << ".lazy_reference"; break;
139  case NoDeadStrip: OS << ".no_dead_strip"; break;
140  case PrivateExtern: OS << ".private_extern"; break;
141  case Protected: OS << ".protected"; break;
142  case Reference: OS << ".reference"; break;
143  case Weak: OS << ".weak"; break;
144  case WeakDefinition: OS << ".weak_definition"; break;
145  case WeakReference: OS << ".weak_reference"; break;
146  }
147
148  OS << ' ' << Symbol->getName() << '\n';
149}
150
151void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
152                                     unsigned Pow2Alignment, bool IsLocal) {
153  if (IsLocal)
154    OS << ".lcomm";
155  else
156    OS << ".comm";
157  OS << ' ' << Symbol->getName() << ',' << Size;
158  if (Pow2Alignment != 0)
159    OS << ',' << Pow2Alignment;
160  OS << '\n';
161}
162
163void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
164                                 unsigned Size, unsigned Pow2Alignment) {
165  // Note: a .zerofill directive does not switch sections
166  // FIXME: Really we would like the segment and section names as well as the
167  // section type to be separate values instead of embedded in the name. Not
168  // all assemblers understand all this stuff though.
169  OS << ".zerofill " << Section->getName();
170  if (Symbol != NULL) {
171    OS << ',' << Symbol->getName() << ',' << Size;
172    if (Pow2Alignment != 0)
173      OS << ',' << Pow2Alignment;
174  }
175  OS << '\n';
176}
177
178void MCAsmStreamer::EmitBytes(const char *Data, unsigned Length) {
179  assert(CurSection && "Cannot emit contents before setting section!");
180  for (unsigned i = 0; i != Length; ++i)
181    OS << ".byte " << (unsigned) Data[i] << '\n';
182}
183
184void MCAsmStreamer::EmitValue(const MCValue &Value, unsigned Size) {
185  assert(CurSection && "Cannot emit contents before setting section!");
186  // Need target hooks to know how to print this.
187  switch (Size) {
188  default:
189    assert(0 && "Invalid size for machine code value!");
190  case 1: OS << ".byte"; break;
191  case 2: OS << ".short"; break;
192  case 4: OS << ".long"; break;
193  case 8: OS << ".quad"; break;
194  }
195
196  OS << ' ' << truncateToSize(Value, Size) << '\n';
197}
198
199void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
200                                         unsigned ValueSize,
201                                         unsigned MaxBytesToEmit) {
202  // Some assemblers don't support .balign, so we always emit as .p2align if
203  // this is a power of two. Otherwise we assume the client knows the target
204  // supports .balign and use that.
205  unsigned Pow2 = Log2_32(ByteAlignment);
206  bool IsPow2 = (1U << Pow2) == ByteAlignment;
207
208  switch (ValueSize) {
209  default:
210    assert(0 && "Invalid size for machine code value!");
211  case 8:
212    assert(0 && "Unsupported alignment size!");
213  case 1: OS << (IsPow2 ? ".p2align" : ".balign"); break;
214  case 2: OS << (IsPow2 ? ".p2alignw" : ".balignw"); break;
215  case 4: OS << (IsPow2 ? ".p2alignl" : ".balignl"); break;
216  }
217
218  OS << ' ' << (IsPow2 ? Pow2 : ByteAlignment);
219
220  OS << ", " << truncateToSize(Value, ValueSize);
221  if (MaxBytesToEmit)
222    OS << ", " << MaxBytesToEmit;
223  OS << '\n';
224}
225
226void MCAsmStreamer::EmitValueToOffset(const MCValue &Offset,
227                                      unsigned char Value) {
228  // FIXME: Verify that Offset is associated with the current section.
229  OS << ".org " << Offset << ", " << (unsigned) Value << '\n';
230}
231
232static raw_ostream &operator<<(raw_ostream &OS, const MCOperand &Op) {
233  if (Op.isReg())
234    return OS << "reg:" << Op.getReg();
235  if (Op.isImm())
236    return OS << "imm:" << Op.getImm();
237  if (Op.isMBBLabel())
238    return OS << "mbblabel:("
239              << Op.getMBBLabelFunction() << ", " << Op.getMBBLabelBlock();
240  assert(Op.isMCValue() && "Invalid operand!");
241  return OS << "val:" << Op.getMCValue();
242}
243
244void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
245  assert(CurSection && "Cannot emit contents before setting section!");
246  // FIXME: Implement proper printing.
247  OS << "MCInst("
248     << "opcode=" << Inst.getOpcode() << ", "
249     << "operands=[";
250  for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
251    if (i)
252      OS << ", ";
253    OS << Inst.getOperand(i);
254  }
255  OS << "])\n";
256}
257
258void MCAsmStreamer::Finish() {
259  OS.flush();
260}
261
262MCStreamer *llvm::createAsmStreamer(MCContext &Context, raw_ostream &OS) {
263  return new MCAsmStreamer(Context, OS);
264}
265