X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FMC%2FMCDwarf.cpp;h=17d164f2c7b628f7bc8f40ad0fd2ad81930678d2;hb=138abae2a2149b2bda3c5e28d3c4db97e3c82663;hp=2da71f96c676ad30ed0000e03a59fb9b5115852f;hpb=7cbf73a73f296167b6e978dbd919ed249e88eeb5;p=oota-llvm.git

diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 2da71f96c67..17d164f2c7b 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -8,10 +8,478 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MC/MCDwarf.h"
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetAsmBackend.h"
 using namespace llvm;
 
+// Given a special op, return the address skip amount (in units of
+// DWARF2_LINE_MIN_INSN_LENGTH.
+#define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
+
+// The maximum address skip amount that can be encoded with a special op.
+#define MAX_SPECIAL_ADDR_DELTA		SPECIAL_ADDR(255)
+
+// First special line opcode - leave room for the standard opcodes.
+// Note: If you want to change this, you'll have to update the
+// "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().  
+#define DWARF2_LINE_OPCODE_BASE		13
+
+// Minimum line offset in a special line info. opcode.  This value
+// was chosen to give a reasonable range of values.
+#define DWARF2_LINE_BASE		-5
+
+// Range of line offsets in a special line info. opcode.
+# define DWARF2_LINE_RANGE		14
+
+// Define the architecture-dependent minimum instruction length (in bytes).
+// This value should be rather too small than too big.
+# define DWARF2_LINE_MIN_INSN_LENGTH	1
+
+// Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
+// this routine is a nop and will be optimized away.
+static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta)
+{
+  if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
+    return AddrDelta;
+  if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
+    // TODO: report this error, but really only once.
+    ;
+  }
+  return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
+}
+
+//
+// This is called when an instruction is assembled into the specified section
+// and if there is information from the last .loc directive that has yet to have
+// a line entry made for it is made.
+//
+void MCLineEntry::Make(MCObjectStreamer *MCOS, const MCSection *Section) {
+  if (!MCOS->getContext().getDwarfLocSeen())
+    return;
+
+  // Create a symbol at in the current section for use in the line entry.
+  MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
+  // Set the value of the symbol to use for the MCLineEntry.
+  MCOS->EmitLabel(LineSym);
+
+  // Get the current .loc info saved in the context.
+  const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
+
+  // Create a (local) line entry with the symbol and the current .loc info.
+  MCLineEntry LineEntry(LineSym, DwarfLoc);
+
+  // clear DwarfLocSeen saying the current .loc info is now used.
+  MCOS->getContext().ClearDwarfLocSeen();
+
+  // Get the MCLineSection for this section, if one does not exist for this
+  // section create it.
+  DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
+    MCOS->getContext().getMCLineSections();
+  MCLineSection *LineSection = MCLineSections[Section];
+  if (!LineSection) {
+    // Create a new MCLineSection.  This will be deleted after the dwarf line
+    // table is created using it by iterating through the MCLineSections
+    // DenseMap.
+    LineSection = new MCLineSection;
+    // Save a pointer to the new LineSection into the MCLineSections DenseMap.
+    MCLineSections[Section] = LineSection;
+  }
+
+  // Add the line entry to this section's entries.
+  LineSection->addLineEntry(LineEntry);
+}
+
+//
+// This helper routine returns an expression of End - Start + IntVal .
+// 
+static inline const MCExpr *MakeStartMinusEndExpr(MCObjectStreamer *MCOS,
+                                                  MCSymbol *Start,
+                                                  MCSymbol *End, int IntVal) {
+  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
+  const MCExpr *Res =
+    MCSymbolRefExpr::Create(End, Variant, MCOS->getContext());
+  const MCExpr *RHS =
+    MCSymbolRefExpr::Create(Start, Variant, MCOS->getContext());
+  const MCExpr *Res1 =
+    MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS->getContext());
+  const MCExpr *Res2 =
+    MCConstantExpr::Create(IntVal, MCOS->getContext());
+  const MCExpr *Res3 =
+    MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS->getContext());
+  return Res3;
+}
+
+// 
+// This emits an "absolute" address used in the start of a dwarf line number
+// table.  This will result in a relocatation entry for the address.
+//
+static inline void EmitDwarfSetAddress(MCObjectStreamer *MCOS,
+                                       MCSymbol *Symbol) {
+  MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
+
+  int sizeof_address = MCOS->getAssembler().getBackend().getPointerSize();
+  MCOS->EmitULEB128Value(sizeof_address + 1);
+
+  MCOS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
+  MCOS->EmitSymbolValue(Symbol, sizeof_address);
+}
+
+//
+// This emits the Dwarf line table for the specified section from the entries
+// in the LineSection.
+//
+static inline bool EmitDwarfLineTable(MCObjectStreamer *MCOS,
+                                      const MCSection *Section,
+                                      MCLineSection *LineSection,
+                                      const MCSection *DwarfLineSection) {
+  unsigned FileNum = 1;
+  unsigned LastLine = 1;
+  unsigned Column = 0;
+  unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
+  unsigned Isa = 0;
+  bool EmittedLineTable = false;
+  MCSymbol *LastLabel = NULL;
+  MCSectionData &DLS =
+    MCOS->getAssembler().getOrCreateSectionData(*DwarfLineSection);
+
+  // Loop through each MCLineEntry and encode the dwarf line number table.
+  for (MCLineSection::iterator
+         it = LineSection->getMCLineEntries()->begin(),
+         ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) {
+
+    if (FileNum != it->getFileNum()) {
+      FileNum = it->getFileNum();
+      MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
+      MCOS->EmitULEB128Value(FileNum);
+    }
+    if (Column != it->getColumn()) {
+      Column = it->getColumn();
+      MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
+      MCOS->EmitULEB128Value(Column);
+    }
+    if (Isa != it->getIsa()) {
+      Isa = it->getIsa();
+      MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
+      MCOS->EmitULEB128Value(Isa);
+    }
+    if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
+      Flags = it->getFlags();
+      MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
+    }
+    if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
+      MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
+    if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
+      MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
+    if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
+      MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
+
+    int64_t LineDelta = it->getLine() - LastLine;
+    MCSymbol *Label = it->getLabel();
+
+    // At this point we want to emit/create the sequence to encode the delta in
+    // line numbers and the increment of the address from the previous Label
+    // and the current Label.
+    if (LastLabel == NULL) {
+      // emit the sequence to set the address
+      EmitDwarfSetAddress(MCOS, Label);
+      // emit the sequence for the LineDelta (from 1) and a zero address delta.
+      MCDwarfLineAddr::Emit(MCOS, LineDelta, 0);
+    }
+    else {
+      // Create an expression for the address delta from the LastLabel and
+      // this Label (plus 0).
+      const MCExpr *AddrDelta = MakeStartMinusEndExpr(MCOS, LastLabel, Label,0);
+      // Create a Dwarf Line fragment for the LineDelta and AddrDelta.
+      new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, &DLS);
+    }
+
+    LastLine = it->getLine();
+    LastLabel = Label;
+    EmittedLineTable = true;
+  }
+
+  // Emit a DW_LNE_end_sequence for the end of the section.
+  // Using the pointer Section create a temporary label at the end of the
+  // section and use that and the LastLabel to compute the address delta
+  // and use INT64_MAX as the line delta which is the signal that this is
+  // actually a DW_LNE_end_sequence.
+
+  // Switch to the section to be able to create a symbol at its end.
+  MCOS->SwitchSection(Section);
+  // Create a symbol at the end of the section.
+  MCSymbol *SectionEnd = MCOS->getContext().CreateTempSymbol();
+  // Set the value of the symbol, as we are at the end of the section.
+  MCOS->EmitLabel(SectionEnd);
+
+  // Switch back the the dwarf line section.
+  MCOS->SwitchSection(DwarfLineSection);
+  // Create an expression for the address delta from the LastLabel and this
+  // SectionEnd label.
+  const MCExpr *AddrDelta = MakeStartMinusEndExpr(MCOS, LastLabel, SectionEnd,
+						  0);
+  // Create a Dwarf Line fragment for the LineDelta and AddrDelta.
+  new MCDwarfLineAddrFragment(INT64_MAX, *AddrDelta, &DLS);
+
+  return EmittedLineTable;
+}
+
+//
+// This emits the Dwarf file and the line tables.
+//
+void MCDwarfFileTable::Emit(MCObjectStreamer *MCOS,
+                            const MCSection *DwarfLineSection) {
+  // Switch to the section where the table will be emitted into.
+  MCOS->SwitchSection(DwarfLineSection);
+
+  // Create a symbol at the beginning of this section.
+  MCSymbol *LineStartSym = MCOS->getContext().CreateTempSymbol();
+  // Set the value of the symbol, as we are at the start of the section.
+  MCOS->EmitLabel(LineStartSym);
+
+  // Create a symbol for the end of the section (to be set when we get there).
+  MCSymbol *LineEndSym = MCOS->getContext().CreateTempSymbol();
+
+  // The first 4 bytes is the total length of the information for this
+  // compilation unit (not including these 4 bytes for the length).
+  MCOS->EmitValue(MakeStartMinusEndExpr(MCOS, LineStartSym, LineEndSym, 4),
+                  4, 0);
+
+  // Next 2 bytes is the Version, which is Dwarf 2.
+  MCOS->EmitIntValue(2, 2);
+
+  // Create a symbol for the end of the prologue (to be set when we get there).
+  MCSymbol *ProEndSym = MCOS->getContext().CreateTempSymbol(); // Lprologue_end
+
+  // Length of the prologue, is the next 4 bytes.  Which is the start of the
+  // section to the end of the prologue.  Not including the 4 bytes for the
+  // total length, the 2 bytes for the version, and these 4 bytes for the
+  // length of the prologue.
+  MCOS->EmitValue(MakeStartMinusEndExpr(MCOS, LineStartSym, ProEndSym,
+                                        (4 + 2 + 4)),
+                  4, 0);
+
+  // Parameters of the state machine, are next.
+  MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
+  MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
+  MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
+  MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
+  MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
+
+  // Standard opcode lengths
+  MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
+  MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
+  MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
+  MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
+  MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
+  MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
+  MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
+  MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
+  MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
+  MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
+  MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
+  MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
+
+  // Put out the directory and file tables.
+
+  // First the directory table.
+  const std::vector<StringRef> &MCDwarfDirs =
+    MCOS->getContext().getMCDwarfDirs();
+  for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
+    MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
+    MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
+  }
+  MCOS->EmitIntValue(0, 1); // Terminate the directory list
+
+  // Second the file table.
+  const std::vector<MCDwarfFile *> &MCDwarfFiles =
+    MCOS->getContext().getMCDwarfFiles();
+  for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
+    MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
+    MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
+    MCOS->EmitULEB128Value(MCDwarfFiles[i]->getDirIndex()); // the Directory num
+    MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
+    MCOS->EmitIntValue(0, 1); // filesize (always 0)
+  }
+  MCOS->EmitIntValue(0, 1); // Terminate the file list
+
+  // This is the end of the prologue, so set the value of the symbol at the
+  // end of the prologue (that was used in a previous expression).
+  MCOS->EmitLabel(ProEndSym);
+
+  // Put out the line tables.
+  bool EmittedLineTable = false;
+  DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
+    MCOS->getContext().getMCLineSections();
+  for (DenseMap<const MCSection *, MCLineSection *>::iterator it =
+	MCLineSections.begin(), ie = MCLineSections.end(); it != ie; ++it) {
+    EmittedLineTable = EmitDwarfLineTable(MCOS, it->first, it->second,
+                                          DwarfLineSection);
+
+    // Now delete the MCLineSections that were created in MCLineEntry::Make()
+    // and used to emit the line table.
+    delete it->second;
+  }
+
+  // If there are no line tables emited then we emit:
+  // The following DW_LNE_set_address sequence to set the address to zero and
+  // the DW_LNE_end_sequence.
+  if (EmittedLineTable == false) {
+    if (MCOS->getAssembler().getBackend().getPointerSize() == 8) {
+      // This is the DW_LNE_set_address sequence for 64-bit code.
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(9, 1);
+      MCOS->EmitIntValue(2, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+    }
+    else {
+      // This is the DW_LNE_set_address sequence for 32-bit code.
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(5, 1);
+      MCOS->EmitIntValue(2, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+      MCOS->EmitIntValue(0, 1);
+    }
+
+    // Lastly emit the DW_LNE_end_sequence which consists of 3 bytes '00 01 01'
+    // (00 is the code for extended opcodes, followed by a ULEB128 length of the
+    // extended opcode (01), and the DW_LNE_end_sequence (01).
+    MCOS->EmitIntValue(0, 1); // DW_LNS_extended_op
+    MCOS->EmitIntValue(1, 1); // ULEB128 length of the extended opcode
+    MCOS->EmitIntValue(1, 1); // DW_LNE_end_sequence
+  }
+
+  // This is the end of the section, so set the value of the symbol at the end
+  // of this section (that was used in a previous expression).
+  MCOS->EmitLabel(LineEndSym);
+}
+
+/// Utility function to compute the size of the encoding.
+uint64_t MCDwarfLineAddr::ComputeSize(int64_t LineDelta, uint64_t AddrDelta) {
+  SmallString<256> Tmp;
+  raw_svector_ostream OS(Tmp);
+  MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
+  return OS.GetNumBytesInBuffer();
+}
+
+/// Utility function to write the encoding to an object writer.
+void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
+                            uint64_t AddrDelta) {
+  SmallString<256> Tmp;
+  raw_svector_ostream OS(Tmp);
+  MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
+  OW->WriteBytes(OS.str());
+}
+
+/// Utility function to emit the encoding to a streamer.
+void MCDwarfLineAddr::Emit(MCObjectStreamer *MCOS, int64_t LineDelta,
+                           uint64_t AddrDelta) {
+  SmallString<256> Tmp;
+  raw_svector_ostream OS(Tmp);
+  MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
+  MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0);
+}
+
+/// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
+void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
+                             raw_ostream &OS) {
+  uint64_t Temp, Opcode;
+  bool NeedCopy = false;
+
+  // Scale the address delta by the minimum instruction length.
+  AddrDelta = ScaleAddrDelta(AddrDelta);
+
+  // A LineDelta of INT64_MAX is a signal that this is actually a
+  // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the 
+  // end_sequence to emit the matrix entry.
+  if (LineDelta == INT64_MAX) {
+    if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
+      OS << char(dwarf::DW_LNS_const_add_pc);
+    else {
+      OS << char(dwarf::DW_LNS_advance_pc);
+      SmallString<32> Tmp;
+      raw_svector_ostream OSE(Tmp);
+      MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
+      OS << OSE.str();
+    }
+    OS << char(dwarf::DW_LNS_extended_op);
+    OS << char(1);
+    OS << char(dwarf::DW_LNE_end_sequence);
+    return;
+  }
+
+  // Bias the line delta by the base.
+  Temp = LineDelta - DWARF2_LINE_BASE;
+
+  // If the line increment is out of range of a special opcode, we must encode
+  // it with DW_LNS_advance_line.
+  if (Temp >= DWARF2_LINE_RANGE) {
+    OS << char(dwarf::DW_LNS_advance_line);
+    SmallString<32> Tmp;
+    raw_svector_ostream OSE(Tmp);
+    MCObjectWriter::EncodeSLEB128(LineDelta, OSE);
+    OS << OSE.str();
+
+    LineDelta = 0;
+    Temp = 0 - DWARF2_LINE_BASE;
+    NeedCopy = true;
+  }
+
+  // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
+  if (LineDelta == 0 && AddrDelta == 0) {
+    OS << char(dwarf::DW_LNS_copy);
+    return;
+  }
+
+  // Bias the opcode by the special opcode base.
+  Temp += DWARF2_LINE_OPCODE_BASE;
+
+  // Avoid overflow when addr_delta is large.
+  if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
+    // Try using a special opcode.
+    Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
+    if (Opcode <= 255) {
+      OS << char(Opcode);
+      return;
+    }
+
+    // Try using DW_LNS_const_add_pc followed by special op.
+    Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
+    if (Opcode <= 255) {
+      OS << char(dwarf::DW_LNS_const_add_pc);
+      OS << char(Opcode);
+      return;
+    }
+  }
+
+  // Otherwise use DW_LNS_advance_pc.
+  OS << char(dwarf::DW_LNS_advance_pc);
+  SmallString<32> Tmp;
+  raw_svector_ostream OSE(Tmp);
+  MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
+  OS << OSE.str();
+
+  if (NeedCopy)
+    OS << char(dwarf::DW_LNS_copy);
+  else
+    OS << char(Temp);
+}
+
 void MCDwarfFile::print(raw_ostream &OS) const {
   OS << '"' << getName() << '"';
 }
@@ -19,3 +487,4 @@ void MCDwarfFile::print(raw_ostream &OS) const {
 void MCDwarfFile::dump() const {
   print(dbgs());
 }
+