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/Target/TargetData.h"
  19 #include "llvm/Target/TargetLoweringObjectFile.h"
  20 #include "llvm/Target/TargetMachine.h"
  21 #include "llvm/ADT/Twine.h"
  22 #include "llvm/Support/Dwarf.h"
  23 using namespace llvm;
  24
  25 /// EmitSLEB128 - emit the specified signed leb128 value.
  26 void AsmPrinter::EmitSLEB128(int Value, const char *Desc) const {
  27   if (isVerbose() && Desc)
  28     OutStreamer.AddComment(Desc);
  29
  30   if (MAI->hasLEB128()) {
  31     // FIXME: MCize.
  32     OutStreamer.EmitRawText("\t.sleb128\t" + Twine(Value));
  33     return;
  34   }
  35
  36   // If we don't have .sleb128, emit as .bytes.
  37   int Sign = Value >> (8 * sizeof(Value) - 1);
  38   bool IsMore;
  39
  40   do {
  41     unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
  42     Value >>= 7;
  43     IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
  44     if (IsMore) Byte |= 0x80;
  45     OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
  46   } while (IsMore);
  47 }
  48
  49 /// EmitULEB128 - emit the specified signed leb128 value.
  50 void AsmPrinter::EmitULEB128(unsigned Value, const char *Desc,
  51                              unsigned PadTo) const {
  52   if (isVerbose() && Desc)
  53     OutStreamer.AddComment(Desc);
  54
  55   if (MAI->hasLEB128() && PadTo == 0) {
  56     // FIXME: MCize.
  57     OutStreamer.EmitRawText("\t.uleb128\t" + Twine(Value));
  58     return;
  59   }
  60
  61   // If we don't have .uleb128 or we want to emit padding, emit as .bytes.
  62   do {
  63     unsigned char Byte = static_cast<unsigned char>(Value & 0x7f);
  64     Value >>= 7;
  65     if (Value || PadTo != 0) Byte |= 0x80;
  66     OutStreamer.EmitIntValue(Byte, 1, /*addrspace*/0);
  67   } while (Value);
  68
  69   if (PadTo) {
  70     if (PadTo > 1)
  71       OutStreamer.EmitFill(PadTo - 1, 0x80/*fillval*/, 0/*addrspace*/);
  72     OutStreamer.EmitFill(1, 0/*fillval*/, 0/*addrspace*/);
  73   }
  74 }
  75
  76 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
  77 void AsmPrinter::EmitCFAByte(unsigned Val) const {
  78   if (isVerbose()) {
  79     if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
  80       OutStreamer.AddComment("DW_CFA_offset + Reg (" +
  81                              Twine(Val-dwarf::DW_CFA_offset) + ")");
  82     else
  83       OutStreamer.AddComment(dwarf::CallFrameString(Val));
  84   }
  85   OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
  86 }
  87
  88 static const char *DecodeDWARFEncoding(unsigned Encoding) {
  89   switch (Encoding) {
  90   case dwarf::DW_EH_PE_absptr: return "absptr";
  91   case dwarf::DW_EH_PE_omit:   return "omit";
  92   case dwarf::DW_EH_PE_pcrel:  return "pcrel";
  93   case dwarf::DW_EH_PE_udata4: return "udata4";
  94   case dwarf::DW_EH_PE_udata8: return "udata8";
  95   case dwarf::DW_EH_PE_sdata4: return "sdata4";
  96   case dwarf::DW_EH_PE_sdata8: return "sdata8";
  97   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
  98   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
  99   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
 100   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: return "pcrel sdata8";
 101   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4:
 102     return "indirect pcrel udata4";
 103   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4:
 104     return "indirect pcrel sdata4";
 105   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8:
 106     return "indirect pcrel udata8";
 107   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8:
 108     return "indirect pcrel sdata8";
 109   }
 110
 111   return "<unknown encoding>";
 112 }
 113
 114
 115 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
 116 /// encoding.  If verbose assembly output is enabled, we output comments
 117 /// describing the encoding.  Desc is an optional string saying what the
 118 /// encoding is specifying (e.g. "LSDA").
 119 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) {
 120   if (isVerbose()) {
 121     if (Desc != 0)
 122       OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
 123                              Twine(DecodeDWARFEncoding(Val)));
 124     else
 125       OutStreamer.AddComment(Twine("Encoding = ") +
 126                              DecodeDWARFEncoding(Val));
 127   }
 128
 129   OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
 130 }
 131
 132 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
 133 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
 134   if (Encoding == dwarf::DW_EH_PE_omit)
 135     return 0;
 136
 137   switch (Encoding & 0x07) {
 138   default: assert(0 && "Invalid encoded value.");
 139   case dwarf::DW_EH_PE_absptr: return TM.getTargetData()->getPointerSize();
 140   case dwarf::DW_EH_PE_udata2: return 2;
 141   case dwarf::DW_EH_PE_udata4: return 4;
 142   case dwarf::DW_EH_PE_udata8: return 8;
 143   }
 144 }
 145
 146 void AsmPrinter::EmitReference(const MCSymbol *Sym, unsigned Encoding) const {
 147   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
 148
 149   const MCExpr *Exp =
 150     TLOF.getExprForDwarfReference(Sym, Mang, MMI, Encoding, OutStreamer);
 151   OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding), /*addrspace*/0);
 152 }
 153
 154 void AsmPrinter::EmitReference(const GlobalValue *GV, unsigned Encoding)const{
 155   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
 156
 157   const MCExpr *Exp =
 158     TLOF.getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, OutStreamer);
 159   OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding), /*addrspace*/0);
 160 }