lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

   1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
   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 // This file implements the Dwarf emissions parts of AsmPrinter.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #define DEBUG_TYPE "asm-printer"
  15 #include "llvm/CodeGen/AsmPrinter.h"
  16 #include "llvm/MC/MCAsmInfo.h"
  17 #include "llvm/MC/MCStreamer.h"
  18 #include "llvm/ADT/Twine.h"
  19 #include "llvm/Support/Dwarf.h"
  20 using namespace llvm;
  21
  22 /// EmitSLEB128 - emit the specified signed leb128 value.
  23 void AsmPrinter::EmitSLEB128(int Value, const char *Desc) const {
  24   if (isVerbose() && Desc)
  25     OutStreamer.AddComment(Desc);
  26
  27   if (MAI->hasLEB128()) {
  28     // FIXME: MCize.
  29     OutStreamer.EmitRawText("\t.sleb128\t" + Twine(Value));
  30     return;
  31   }
  32
  33   // If we don't have .sleb128, emit as .bytes.
  34   int Sign = Value >> (8 * sizeof(Value) - 1);
  35   bool IsMore;
  36
  37   do {
  38     unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
  39     Value >>= 7;
  40     IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
  41     if (IsMore) Byte |= 0x80;
  42     OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
  43   } while (IsMore);
  44 }
  45
  46 /// EmitULEB128 - emit the specified signed leb128 value.
  47 void AsmPrinter::EmitULEB128(unsigned Value, const char *Desc,
  48                              unsigned PadTo) const {
  49   if (isVerbose() && Desc)
  50     OutStreamer.AddComment(Desc);
  51
  52   if (MAI->hasLEB128() && PadTo == 0) {
  53     // FIXME: MCize.
  54     OutStreamer.EmitRawText("\t.uleb128\t" + Twine(Value));
  55     return;
  56   }
  57
  58   // If we don't have .uleb128 or we want to emit padding, emit as .bytes.
  59   do {
  60     unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
  61     Value >>= 7;
  62     if (Value || PadTo != 0) Byte |= 0x80;
  63     OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
  64   } while (Value);
  65
  66   if (PadTo) {
  67     if (PadTo > 1)
  68       OutStreamer.EmitFill(PadTo - 1, 0x80/*fillval*/, 0/*addrspace*/);
  69     OutStreamer.EmitFill(1, 0/*fillval*/, 0/*addrspace*/);
  70   }
  71 }
  72
  73 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
  74 void AsmPrinter::EmitCFAByte(unsigned Val) const {
  75   if (isVerbose()) {
  76     if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
  77       OutStreamer.AddComment("DW_CFA_offset + Reg (" +
  78                              Twine(Val-dwarf::DW_CFA_offset) + ")");
  79     else
  80       OutStreamer.AddComment(dwarf::CallFrameString(Val));
  81   }
  82   OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
  83 }
  84
  85 static const char *DecodeDWARFEncoding(unsigned Encoding) {
  86   switch (Encoding) {
  87   case dwarf::DW_EH_PE_absptr: return "absptr";
  88   case dwarf::DW_EH_PE_omit:   return "omit";
  89   case dwarf::DW_EH_PE_pcrel:  return "pcrel";
  90   case dwarf::DW_EH_PE_udata4: return "udata4";
  91   case dwarf::DW_EH_PE_udata8: return "udata8";
  92   case dwarf::DW_EH_PE_sdata4: return "sdata4";
  93   case dwarf::DW_EH_PE_sdata8: return "sdata8";
  94   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
  95   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
  96   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
  97   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: return "pcrel sdata8";
  98   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4:
  99     return "indirect pcrel udata4";
 100   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4:
 101     return "indirect pcrel sdata4";
 102   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8:
 103     return "indirect pcrel udata8";
 104   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8:
 105     return "indirect pcrel sdata8";
 106   }
 107
 108   return "<unknown encoding>";
 109 }
 110
 111
 112 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
 113 /// encoding.  If verbose assembly output is enabled, we output comments
 114 /// describing the encoding.  Desc is an optional string saying what the
 115 /// encoding is specifying (e.g. "LSDA").
 116 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) {
 117   if (isVerbose()) {
 118     if (Desc != 0)
 119       OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
 120                              Twine(DecodeDWARFEncoding(Val)));
 121     else
 122       OutStreamer.AddComment(Twine("Encoding = ") +
 123                              DecodeDWARFEncoding(Val));
 124   }
 125
 126   OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
 127 }
 128