lib/CodeGen/AsmPrinter/DwarfPrinter.cpp

   1 //===--- lib/CodeGen/DwarfPrinter.cpp - Dwarf Printer ---------------------===//
   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 // Emit general DWARF directives.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "DwarfPrinter.h"
  15 #include "llvm/Module.h"
  16 #include "llvm/CodeGen/AsmPrinter.h"
  17 #include "llvm/CodeGen/MachineFrameInfo.h"
  18 #include "llvm/CodeGen/MachineFunction.h"
  19 #include "llvm/CodeGen/MachineModuleInfo.h"
  20 #include "llvm/MC/MCAsmInfo.h"
  21 #include "llvm/MC/MCContext.h"
  22 #include "llvm/MC/MCExpr.h"
  23 #include "llvm/MC/MCStreamer.h"
  24 #include "llvm/MC/MCSymbol.h"
  25 #include "llvm/Target/TargetData.h"
  26 #include "llvm/Target/TargetFrameInfo.h"
  27 #include "llvm/Target/TargetLoweringObjectFile.h"
  28 #include "llvm/Target/TargetRegisterInfo.h"
  29 #include "llvm/Target/TargetMachine.h"
  30 #include "llvm/Support/Dwarf.h"
  31 #include "llvm/Support/ErrorHandling.h"
  32 #include "llvm/ADT/SmallString.h"
  33 using namespace llvm;
  34
  35 DwarfPrinter::DwarfPrinter(AsmPrinter *A)
  36 : Asm(A), MAI(A->MAI), TD(Asm->TM.getTargetData()),
  37   RI(Asm->TM.getRegisterInfo()), M(NULL), MF(NULL), MMI(NULL),
  38   SubprogramCount(0) {}
  39
  40 /// SizeOfEncodedValue - Return the size of the encoding in bytes.
  41 unsigned DwarfPrinter::SizeOfEncodedValue(unsigned Encoding) const {
  42   if (Encoding == dwarf::DW_EH_PE_omit)
  43     return 0;
  44
  45   switch (Encoding & 0x07) {
  46   case dwarf::DW_EH_PE_absptr:
  47     return TD->getPointerSize();
  48   case dwarf::DW_EH_PE_udata2:
  49     return 2;
  50   case dwarf::DW_EH_PE_udata4:
  51     return 4;
  52   case dwarf::DW_EH_PE_udata8:
  53     return 8;
  54   }
  55
  56   assert(0 && "Invalid encoded value.");
  57   return 0;
  58 }
  59
  60 static const char *DecodeDWARFEncoding(unsigned Encoding) {
  61   switch (Encoding) {
  62   case dwarf::DW_EH_PE_absptr: return "absptr";
  63   case dwarf::DW_EH_PE_omit:   return "omit";
  64   case dwarf::DW_EH_PE_pcrel:  return "pcrel";
  65   case dwarf::DW_EH_PE_udata4: return "udata4";
  66   case dwarf::DW_EH_PE_udata8: return "udata8";
  67   case dwarf::DW_EH_PE_sdata4: return "sdata4";
  68   case dwarf::DW_EH_PE_sdata8: return "sdata8";
  69   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4: return "pcrel udata4";
  70   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4: return "pcrel sdata4";
  71   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8: return "pcrel udata8";
  72   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8: return "pcrel sdata8";
  73   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4:
  74     return "indirect pcrel udata4";
  75   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4:
  76     return "indirect pcrel sdata4";
  77   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8:
  78     return "indirect pcrel udata8";
  79   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8:
  80     return "indirect pcrel sdata8";
  81   }
  82
  83   return "<unknown encoding>";
  84 }
  85
  86 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
  87 /// encoding.  If verbose assembly output is enabled, we output comments
  88 /// describing the encoding.  Desc is an optional string saying what the
  89 /// encoding is specifying (e.g. "LSDA").
  90 void DwarfPrinter::EmitEncodingByte(unsigned Val, const char *Desc) {
  91   if (Asm->isVerbose()) {
  92     if (Desc != 0)
  93       Asm->OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
  94                                   Twine(DecodeDWARFEncoding(Val)));
  95     else
  96       Asm->OutStreamer.AddComment(Twine("Encoding = ") +
  97                                   DecodeDWARFEncoding(Val));
  98   }
  99
 100   Asm->OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
 101 }
 102
 103 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
 104 void DwarfPrinter::EmitCFAByte(unsigned Val) {
 105   if (Asm->isVerbose()) {
 106     if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
 107       Asm->OutStreamer.AddComment("DW_CFA_offset + Reg (" +
 108                                   Twine(Val-dwarf::DW_CFA_offset) + ")");
 109     else
 110       Asm->OutStreamer.AddComment(dwarf::CallFrameString(Val));
 111   }
 112   Asm->OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
 113 }
 114
 115 void DwarfPrinter::EmitReference(const MCSymbol *Sym, unsigned Encoding) const {
 116   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 117
 118   const MCExpr *Exp = TLOF.getExprForDwarfReference(Sym, Asm->Mang,
 119                                                     Asm->MMI, Encoding,
 120                                                     Asm->OutStreamer);
 121   Asm->OutStreamer.EmitValue(Exp, SizeOfEncodedValue(Encoding), /*addrspace*/0);
 122 }
 123
 124 void DwarfPrinter::EmitReference(const GlobalValue *GV, unsigned Encoding)const{
 125   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 126
 127   const MCExpr *Exp =
 128     TLOF.getExprForDwarfGlobalReference(GV, Asm->Mang, Asm->MMI, Encoding,
 129                                         Asm->OutStreamer);
 130   Asm->OutStreamer.EmitValue(Exp, SizeOfEncodedValue(Encoding), /*addrspace*/0);
 131 }
 132
 133 /// EmitDifference - Emit the difference between two labels.  If this assembler
 134 /// supports .set, we emit a .set of a temporary and then use it in the .word.
 135 void DwarfPrinter::EmitDifference(const MCSymbol *TagHi, const MCSymbol *TagLo,
 136                                   bool IsSmall) {
 137   unsigned Size = IsSmall ? 4 : TD->getPointerSize();
 138   Asm->EmitLabelDifference(TagHi, TagLo, Size);
 139 }
 140
 141 void DwarfPrinter::EmitSectionOffset(const MCSymbol *Label,
 142                                      const MCSymbol *Section,
 143                                      bool IsSmall, bool isEH) {
 144   bool isAbsolute;
 145   if (isEH)
 146     isAbsolute = MAI->isAbsoluteEHSectionOffsets();
 147   else
 148     isAbsolute = MAI->isAbsoluteDebugSectionOffsets();
 149
 150   if (!isAbsolute)
 151     return EmitDifference(Label, Section, IsSmall);
 152
 153   // On COFF targets, we have to emit the weird .secrel32 directive.
 154   if (const char *SecOffDir = MAI->getDwarfSectionOffsetDirective()) {
 155     // FIXME: MCize.
 156     Asm->OutStreamer.EmitRawText(SecOffDir + Twine(Label->getName()));
 157   } else {
 158     unsigned Size = IsSmall ? 4 : TD->getPointerSize();
 159     Asm->OutStreamer.EmitSymbolValue(Label, Size, 0/*AddrSpace*/);
 160   }
 161 }
 162
 163 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
 164 /// frame.
 165 void DwarfPrinter::EmitFrameMoves(MCSymbol *BaseLabel,
 166                                   const std::vector<MachineMove> &Moves,
 167                                   bool isEH) {
 168   int stackGrowth = TD->getPointerSize();
 169   if (Asm->TM.getFrameInfo()->getStackGrowthDirection() !=
 170       TargetFrameInfo::StackGrowsUp)
 171     stackGrowth *= -1;
 172
 173   for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
 174     const MachineMove &Move = Moves[i];
 175     MCSymbol *Label = Move.getLabel();
 176     // Throw out move if the label is invalid.
 177     if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
 178
 179     const MachineLocation &Dst = Move.getDestination();
 180     const MachineLocation &Src = Move.getSource();
 181
 182     // Advance row if new location.
 183     if (BaseLabel && Label) {
 184       MCSymbol *ThisSym = Label;
 185       if (ThisSym != BaseLabel) {
 186         EmitCFAByte(dwarf::DW_CFA_advance_loc4);
 187         EmitDifference(ThisSym, BaseLabel, true);
 188         BaseLabel = ThisSym;
 189       }
 190     }
 191
 192     // If advancing cfa.
 193     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
 194       if (!Src.isReg()) {
 195         if (Src.getReg() == MachineLocation::VirtualFP) {
 196           EmitCFAByte(dwarf::DW_CFA_def_cfa_offset);
 197         } else {
 198           EmitCFAByte(dwarf::DW_CFA_def_cfa);
 199           Asm->EmitULEB128(RI->getDwarfRegNum(Src.getReg(), isEH), "Register");
 200         }
 201
 202         int Offset = -Src.getOffset();
 203         Asm->EmitULEB128(Offset, "Offset");
 204       } else {
 205         llvm_unreachable("Machine move not supported yet.");
 206       }
 207     } else if (Src.isReg() &&
 208                Src.getReg() == MachineLocation::VirtualFP) {
 209       if (Dst.isReg()) {
 210         EmitCFAByte(dwarf::DW_CFA_def_cfa_register);
 211         Asm->EmitULEB128(RI->getDwarfRegNum(Dst.getReg(), isEH), "Register");
 212       } else {
 213         llvm_unreachable("Machine move not supported yet.");
 214       }
 215     } else {
 216       unsigned Reg = RI->getDwarfRegNum(Src.getReg(), isEH);
 217       int Offset = Dst.getOffset() / stackGrowth;
 218
 219       if (Offset < 0) {
 220         EmitCFAByte(dwarf::DW_CFA_offset_extended_sf);
 221         Asm->EmitULEB128(Reg, "Reg");
 222         Asm->EmitSLEB128(Offset, "Offset");
 223       } else if (Reg < 64) {
 224         EmitCFAByte(dwarf::DW_CFA_offset + Reg);
 225         Asm->EmitULEB128(Offset, "Offset");
 226       } else {
 227         EmitCFAByte(dwarf::DW_CFA_offset_extended);
 228         Asm->EmitULEB128(Reg, "Reg");
 229         Asm->EmitULEB128(Offset, "Offset");
 230       }
 231     }
 232   }
 233 }