lib/MC/MCAsmStreamer.cpp

   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/CodeGen/AsmPrinter.h"
  13 #include "llvm/MC/MCAsmInfo.h"
  14 #include "llvm/MC/MCCodeEmitter.h"
  15 #include "llvm/MC/MCContext.h"
  16 #include "llvm/MC/MCExpr.h"
  17 #include "llvm/MC/MCInst.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"
  24 using namespace llvm;
  25
  26 namespace {
  27
  28 class MCAsmStreamer : public MCStreamer {
  29   raw_ostream &OS;
  30   const MCAsmInfo &MAI;
  31   AsmPrinter *Printer;
  32   MCCodeEmitter *Emitter;
  33 public:
  34   MCAsmStreamer(MCContext &Context, raw_ostream &_OS, const MCAsmInfo &tai,
  35                 AsmPrinter *_Printer, MCCodeEmitter *_Emitter)
  36     : MCStreamer(Context), OS(_OS), MAI(tai), Printer(_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(const 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
  81 static 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
  86 static inline const MCExpr *truncateToSize(const MCExpr *Value,
  87                                            unsigned Bytes) {
  88   // FIXME: Do we really need this routine?
  89   return Value;
  90 }
  91
  92 void 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
 100 void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
 101   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 102   assert(CurSection && "Cannot emit before setting section!");
 103
 104   Symbol->print(OS, &MAI);
 105   OS << ":\n";
 106   Symbol->setSection(*CurSection);
 107 }
 108
 109 void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
 110   switch (Flag) {
 111   default: assert(0 && "Invalid flag!");
 112   case SubsectionsViaSymbols: OS << ".subsections_via_symbols"; break;
 113   }
 114   OS << '\n';
 115 }
 116
 117 void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
 118   // Only absolute symbols can be redefined.
 119   assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
 120          "Cannot define a symbol twice!");
 121
 122   Symbol->print(OS, &MAI);
 123   OS << " = ";
 124   Value->print(OS, &MAI);
 125   OS << '\n';
 126 }
 127
 128 void 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 << ' ';
 146   Symbol->print(OS, &MAI);
 147   OS << '\n';
 148 }
 149
 150 void MCAsmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
 151   OS << ".desc" << ' ';
 152   Symbol->print(OS, &MAI);
 153   OS << ',' << DescValue << '\n';
 154 }
 155
 156 void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, unsigned Size,
 157                                      unsigned ByteAlignment) {
 158   OS << ".comm ";
 159   Symbol->print(OS, &MAI);
 160   OS << ',' << Size;
 161   if (ByteAlignment != 0)
 162     OS << ',' << Log2_32(ByteAlignment);
 163   OS << '\n';
 164 }
 165
 166 void MCAsmStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
 167                                  unsigned Size, unsigned ByteAlignment) {
 168   // Note: a .zerofill directive does not switch sections.
 169   OS << ".zerofill ";
 170
 171   // This is a mach-o specific directive.
 172   const MCSectionMachO *MOSection = ((const MCSectionMachO*)Section);
 173   OS << MOSection->getSegmentName() << "," << MOSection->getSectionName();
 174
 175   if (Symbol != NULL) {
 176     OS << ',';
 177     Symbol->print(OS, &MAI);
 178     OS << ',' << Size;
 179     if (ByteAlignment != 0)
 180       OS << ',' << Log2_32(ByteAlignment);
 181   }
 182   OS << '\n';
 183 }
 184
 185 void MCAsmStreamer::EmitBytes(const StringRef &Data) {
 186   assert(CurSection && "Cannot emit contents before setting section!");
 187   for (unsigned i = 0, e = Data.size(); i != e; ++i)
 188     OS << ".byte " << (unsigned) (unsigned char) Data[i] << '\n';
 189 }
 190
 191 void MCAsmStreamer::EmitValue(const MCExpr *Value, unsigned Size) {
 192   assert(CurSection && "Cannot emit contents before setting section!");
 193   // Need target hooks to know how to print this.
 194   switch (Size) {
 195   default:
 196     llvm_unreachable("Invalid size for machine code value!");
 197   case 1: OS << ".byte"; break;
 198   case 2: OS << ".short"; break;
 199   case 4: OS << ".long"; break;
 200   case 8: OS << ".quad"; break;
 201   }
 202
 203   OS << ' ';
 204   truncateToSize(Value, Size)->print(OS, &MAI);
 205   OS << '\n';
 206 }
 207
 208 void MCAsmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
 209                                          unsigned ValueSize,
 210                                          unsigned MaxBytesToEmit) {
 211   // Some assemblers don't support non-power of two alignments, so we always
 212   // emit alignments as a power of two if possible.
 213   if (isPowerOf2_32(ByteAlignment)) {
 214     switch (ValueSize) {
 215     default: llvm_unreachable("Invalid size for machine code value!");
 216     case 1: OS << MAI.getAlignDirective(); break;
 217     // FIXME: use MAI for this!
 218     case 2: OS << ".p2alignw "; break;
 219     case 4: OS << ".p2alignl "; break;
 220     case 8: llvm_unreachable("Unsupported alignment size!");
 221     }
 222
 223     if (MAI.getAlignmentIsInBytes())
 224       OS << ByteAlignment;
 225     else
 226       OS << Log2_32(ByteAlignment);
 227
 228     if (Value || MaxBytesToEmit) {
 229       OS << ", 0x";
 230       OS.write_hex(truncateToSize(Value, ValueSize));
 231
 232       if (MaxBytesToEmit)
 233         OS << ", " << MaxBytesToEmit;
 234     }
 235     OS << '\n';
 236     return;
 237   }
 238
 239   // Non-power of two alignment.  This is not widely supported by assemblers.
 240   // FIXME: Parameterize this based on MAI.
 241   switch (ValueSize) {
 242   default: llvm_unreachable("Invalid size for machine code value!");
 243   case 1: OS << ".balign";  break;
 244   case 2: OS << ".balignw"; break;
 245   case 4: OS << ".balignl"; break;
 246   case 8: llvm_unreachable("Unsupported alignment size!");
 247   }
 248
 249   OS << ' ' << ByteAlignment;
 250   OS << ", " << truncateToSize(Value, ValueSize);
 251   if (MaxBytesToEmit)
 252     OS << ", " << MaxBytesToEmit;
 253   OS << '\n';
 254 }
 255
 256 void MCAsmStreamer::EmitValueToOffset(const MCExpr *Offset,
 257                                       unsigned char Value) {
 258   // FIXME: Verify that Offset is associated with the current section.
 259   OS << ".org ";
 260   Offset->print(OS, &MAI);
 261   OS << ", " << (unsigned) Value << '\n';
 262 }
 263
 264 void MCAsmStreamer::EmitInstruction(const MCInst &Inst) {
 265   assert(CurSection && "Cannot emit contents before setting section!");
 266
 267   // If we have an AsmPrinter, use that to print.
 268   if (Printer) {
 269     Printer->printMCInst(&Inst);
 270     OS << '\n';
 271
 272     // Show the encoding if we have a code emitter.
 273     if (Emitter) {
 274       SmallString<256> Code;
 275       raw_svector_ostream VecOS(Code);
 276       Emitter->EncodeInstruction(Inst, VecOS);
 277       VecOS.flush();
 278
 279       OS.indent(20);
 280       OS << " # encoding: [";
 281       for (unsigned i = 0, e = Code.size(); i != e; ++i) {
 282         if (i)
 283           OS << ',';
 284         OS << format("%#04x", uint8_t(Code[i]));
 285       }
 286       OS << "]\n";
 287     }
 288
 289     return;
 290   }
 291
 292   // Otherwise fall back to a structural printing for now. Eventually we should
 293   // always have access to the target specific printer.
 294   Inst.print(OS, &MAI);
 295   OS << '\n';
 296 }
 297
 298 void MCAsmStreamer::Finish() {
 299   OS.flush();
 300 }
 301
 302 MCStreamer *llvm::createAsmStreamer(MCContext &Context, raw_ostream &OS,
 303                                     const MCAsmInfo &MAI, AsmPrinter *AP,
 304                                     MCCodeEmitter *CE) {
 305   return new MCAsmStreamer(Context, OS, MAI, AP, CE);
 306 }