//===----------------------------------------------------------------------===//
#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() << '"';
}
void MCDwarfFile::dump() const {
print(dbgs());
}
+
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