[DWARF parser] Cleanup code in DWARFDebugLine.

Streamline parsing and dumping line tables:
Prefer composition to multiple inheritance in DWARFDebugLine::ParsingState.
Get rid of the weird concept of "DumpingState" structure.

was:
  DWARFDebugLine::DumpingState state(OS);
  DWARFDebugLine::parseStatementTable(..., state);
now:
  DWARFDebugLine::LineTable LineTable;
  LineTable.parse(...);
  LineTable.dump(OS);

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207599 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 112 insertions, 128 deletions

diff --git a/lib/DebugInfo/DWARFContext.cpp b/lib/DebugInfo/DWARFContext.cpp
index 6503207dae..3d04e73903 100644
--- a/lib/DebugInfo/DWARFContext.cpp
+++ b/lib/DebugInfo/DWARFContext.cpp
@@ -130,8 +130,9 @@ void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType) {
       if (stmtOffset != -1U) {
         DataExtractor lineData(getLineSection().Data, isLittleEndian(),
                                savedAddressByteSize);
-        DWARFDebugLine::DumpingState state(OS);
-        DWARFDebugLine::parseStatementTable(lineData, &getLineSection().Relocs, &stmtOffset, state);
+        DWARFDebugLine::LineTable LineTable;
+        LineTable.parse(lineData, &getLineSection().Relocs, &stmtOffset);
+        LineTable.dump(OS);
       }
     }
   }
@@ -141,9 +142,11 @@ void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType) {
     unsigned stmtOffset = 0;
     DataExtractor lineData(getLineDWOSection().Data, isLittleEndian(),
                            savedAddressByteSize);
-    DWARFDebugLine::DumpingState state(OS);
-    while (state.Prologue.parse(lineData, &stmtOffset))
-      state.finalize();
+    DWARFDebugLine::LineTable LineTable;
+    while (LineTable.Prologue.parse(lineData, &stmtOffset)) {
+      LineTable.dump(OS);
+      LineTable.clear();
+    }
   }
 
   if (DumpType == DIDT_All || DumpType == DIDT_Str) {
diff --git a/lib/DebugInfo/DWARFDebugLine.cpp b/lib/DebugInfo/DWARFDebugLine.cpp
index 8ca7ec18d2..a5261d7644 100644
--- a/lib/DebugInfo/DWARFDebugLine.cpp
+++ b/lib/DebugInfo/DWARFDebugLine.cpp
@@ -192,50 +192,34 @@ void DWARFDebugLine::LineTable::clear() {
   Sequences.clear();
 }
 
-DWARFDebugLine::State::~State() {}
+DWARFDebugLine::ParsingState::ParsingState(struct LineTable *LT)
+    : LineTable(LT), RowNumber(0) {
+  resetRowAndSequence();
+}
 
-void DWARFDebugLine::State::appendRowToMatrix(uint32_t offset) {
-  if (Sequence::Empty) {
-    // Record the beginning of instruction sequence.
-    Sequence::Empty = false;
-    Sequence::LowPC = Address;
-    Sequence::FirstRowIndex = row;
-  }
-  ++row;  // Increase the row number.
-  LineTable::appendRow(*this);
-  if (EndSequence) {
-    // Record the end of instruction sequence.
-    Sequence::HighPC = Address;
-    Sequence::LastRowIndex = row;
-    if (Sequence::isValid())
-      LineTable::appendSequence(*this);
-    Sequence::reset();
-  }
-  Row::postAppend();
+void DWARFDebugLine::ParsingState::resetRowAndSequence() {
+  Row.reset(LineTable->Prologue.DefaultIsStmt);
+  Sequence.reset();
 }
 
-void DWARFDebugLine::State::finalize() {
-  row = DoneParsingLineTable;
-  if (!Sequence::Empty) {
-    fprintf(stderr, "warning: last sequence in debug line table is not"
-                    "terminated!\n");
+void DWARFDebugLine::ParsingState::appendRowToMatrix(uint32_t offset) {
+  if (Sequence.Empty) {
+    // Record the beginning of instruction sequence.
+    Sequence.Empty = false;
+    Sequence.LowPC = Row.Address;
+    Sequence.FirstRowIndex = RowNumber;
   }
-  // Sort all sequences so that address lookup will work faster.
-  if (!Sequences.empty()) {
-    std::sort(Sequences.begin(), Sequences.end(), Sequence::orderByLowPC);
-    // Note: actually, instruction address ranges of sequences should not
-    // overlap (in shared objects and executables). If they do, the address
-    // lookup would still work, though, but result would be ambiguous.
-    // We don't report warning in this case. For example,
-    // sometimes .so compiled from multiple object files contains a few
-    // rudimentary sequences for address ranges [0x0, 0xsomething).
+  ++RowNumber;
+  LineTable->appendRow(Row);
+  if (Row.EndSequence) {
+    // Record the end of instruction sequence.
+    Sequence.HighPC = Row.Address;
+    Sequence.LastRowIndex = RowNumber;
+    if (Sequence.isValid())
+      LineTable->appendSequence(Sequence);
+    Sequence.reset();
   }
-}
-
-DWARFDebugLine::DumpingState::~DumpingState() {}
-
-void DWARFDebugLine::DumpingState::finalize() {
-  LineTable::dump(OS);
+  Row.postAppend();
 }
 
 const DWARFDebugLine::LineTable *
@@ -251,33 +235,31 @@ DWARFDebugLine::getOrParseLineTable(DataExtractor debug_line_data,
                                     uint32_t offset) {
   std::pair<LineTableIter, bool> pos =
     LineTableMap.insert(LineTableMapTy::value_type(offset, LineTable()));
+  LineTable *LT = &pos.first->second;
   if (pos.second) {
-    // Parse and cache the line table for at this offset.
-    State state;
-    if (!parseStatementTable(debug_line_data, RelocMap, &offset, state))
+    if (!LT->parse(debug_line_data, RelocMap, &offset))
       return nullptr;
-    pos.first->second = state;
   }
-  return &pos.first->second;
+  return LT;
 }
 
-bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
-                                         const RelocAddrMap *RMap,
-                                         uint32_t *offset_ptr, State &state) {
+bool DWARFDebugLine::LineTable::parse(DataExtractor debug_line_data,
+                                      const RelocAddrMap *RMap,
+                                      uint32_t *offset_ptr) {
   const uint32_t debug_line_offset = *offset_ptr;
 
-  Prologue *prologue = &state.Prologue;
+  clear();
 
-  if (!prologue->parse(debug_line_data, offset_ptr)) {
+  if (!Prologue.parse(debug_line_data, offset_ptr)) {
     // Restore our offset and return false to indicate failure!
     *offset_ptr = debug_line_offset;
     return false;
   }
 
-  const uint32_t end_offset = debug_line_offset + prologue->TotalLength +
-                              sizeof(prologue->TotalLength);
+  const uint32_t end_offset = debug_line_offset + Prologue.TotalLength +
+                              sizeof(Prologue.TotalLength);
 
-  state.reset();
+  ParsingState State(this);
 
   while (*offset_ptr < end_offset) {
     uint8_t opcode = debug_line_data.getU8(offset_ptr);
@@ -299,9 +281,9 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
         // with a DW_LNE_end_sequence instruction which creates a row whose
         // address is that of the byte after the last target machine instruction
         // of the sequence.
-        state.EndSequence = true;
-        state.appendRowToMatrix(*offset_ptr);
-        state.reset();
+        State.Row.EndSequence = true;
+        State.appendRowToMatrix(*offset_ptr);
+        State.resetRowAndSequence();
         break;
 
       case DW_LNE_set_address:
@@ -316,9 +298,10 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
           RelocAddrMap::const_iterator AI = RMap->find(*offset_ptr);
           if (AI != RMap->end()) {
              const std::pair<uint8_t, int64_t> &R = AI->second;
-             state.Address = debug_line_data.getAddress(offset_ptr) + R.second;
+             State.Row.Address =
+                 debug_line_data.getAddress(offset_ptr) + R.second;
           } else
-            state.Address = debug_line_data.getAddress(offset_ptr);
+            State.Row.Address = debug_line_data.getAddress(offset_ptr);
         }
         break;
 
@@ -349,12 +332,12 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
           fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr);
           fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr);
           fileEntry.Length = debug_line_data.getULEB128(offset_ptr);
-          prologue->FileNames.push_back(fileEntry);
+          Prologue.FileNames.push_back(fileEntry);
         }
         break;
 
       case DW_LNE_set_discriminator:
-        state.Discriminator = debug_line_data.getULEB128(offset_ptr);
+        State.Row.Discriminator = debug_line_data.getULEB128(offset_ptr);
         break;
 
       default:
@@ -363,52 +346,52 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
         (*offset_ptr) += arg_size;
         break;
       }
-    } else if (opcode < prologue->OpcodeBase) {
+    } else if (opcode < Prologue.OpcodeBase) {
       switch (opcode) {
       // Standard Opcodes
       case DW_LNS_copy:
         // Takes no arguments. Append a row to the matrix using the
         // current values of the state-machine registers. Then set
         // the basic_block register to false.
-        state.appendRowToMatrix(*offset_ptr);
+        State.appendRowToMatrix(*offset_ptr);
         break;
 
       case DW_LNS_advance_pc:
         // Takes a single unsigned LEB128 operand, multiplies it by the
         // min_inst_length field of the prologue, and adds the
         // result to the address register of the state machine.
-        state.Address += debug_line_data.getULEB128(offset_ptr) *
-                         prologue->MinInstLength;
+        State.Row.Address +=
+            debug_line_data.getULEB128(offset_ptr) * Prologue.MinInstLength;
         break;
 
       case DW_LNS_advance_line:
         // Takes a single signed LEB128 operand and adds that value to
         // the line register of the state machine.
-        state.Line += debug_line_data.getSLEB128(offset_ptr);
+        State.Row.Line += debug_line_data.getSLEB128(offset_ptr);
         break;
 
       case DW_LNS_set_file:
         // Takes a single unsigned LEB128 operand and stores it in the file
         // register of the state machine.
-        state.File = debug_line_data.getULEB128(offset_ptr);
+        State.Row.File = debug_line_data.getULEB128(offset_ptr);
         break;
 
       case DW_LNS_set_column:
         // Takes a single unsigned LEB128 operand and stores it in the
         // column register of the state machine.
-        state.Column = debug_line_data.getULEB128(offset_ptr);
+        State.Row.Column = debug_line_data.getULEB128(offset_ptr);
         break;
 
       case DW_LNS_negate_stmt:
         // Takes no arguments. Set the is_stmt register of the state
         // machine to the logical negation of its current value.
-        state.IsStmt = !state.IsStmt;
+        State.Row.IsStmt = !State.Row.IsStmt;
         break;
 
       case DW_LNS_set_basic_block:
         // Takes no arguments. Set the basic_block register of the
         // state machine to true
-        state.BasicBlock = true;
+        State.Row.BasicBlock = true;
         break;
 
       case DW_LNS_const_add_pc:
@@ -424,10 +407,10 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
         // than twice that range will it need to use both DW_LNS_advance_pc
         // and a special opcode, requiring three or more bytes.
         {
-          uint8_t adjust_opcode = 255 - prologue->OpcodeBase;
-          uint64_t addr_offset = (adjust_opcode / prologue->LineRange) *
-                                 prologue->MinInstLength;
-          state.Address += addr_offset;
+          uint8_t adjust_opcode = 255 - Prologue.OpcodeBase;
+          uint64_t addr_offset =
+              (adjust_opcode / Prologue.LineRange) * Prologue.MinInstLength;
+          State.Row.Address += addr_offset;
         }
         break;
 
@@ -441,25 +424,25 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
         // judge when the computation of a special opcode overflows and
         // requires the use of DW_LNS_advance_pc. Such assemblers, however,
         // can use DW_LNS_fixed_advance_pc instead, sacrificing compression.
-        state.Address += debug_line_data.getU16(offset_ptr);
+        State.Row.Address += debug_line_data.getU16(offset_ptr);
         break;
 
       case DW_LNS_set_prologue_end:
         // Takes no arguments. Set the prologue_end register of the
         // state machine to true
-        state.PrologueEnd = true;
+        State.Row.PrologueEnd = true;
         break;
 
       case DW_LNS_set_epilogue_begin:
         // Takes no arguments. Set the basic_block register of the
         // state machine to true
-        state.EpilogueBegin = true;
+        State.Row.EpilogueBegin = true;
         break;
 
       case DW_LNS_set_isa:
         // Takes a single unsigned LEB128 operand and stores it in the
         // column register of the state machine.
-        state.Isa = debug_line_data.getULEB128(offset_ptr);
+        State.Row.Isa = debug_line_data.getULEB128(offset_ptr);
         break;
 
       default:
@@ -467,9 +450,9 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
         // of such opcodes because they are specified in the prologue
         // as a multiple of LEB128 operands for each opcode.
         {
-          assert(opcode - 1U < prologue->StandardOpcodeLengths.size());
-          uint8_t opcode_length = prologue->StandardOpcodeLengths[opcode - 1];
-          for (uint8_t i=0; i<opcode_length; ++i)
+          assert(opcode - 1U < Prologue.StandardOpcodeLengths.size());
+          uint8_t opcode_length = Prologue.StandardOpcodeLengths[opcode - 1];
+          for (uint8_t i = 0; i < opcode_length; ++i)
             debug_line_data.getULEB128(offset_ptr);
         }
         break;
@@ -508,18 +491,32 @@ bool DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
       //
       // line increment = line_base + (adjusted opcode % line_range)
 
-      uint8_t adjust_opcode = opcode - prologue->OpcodeBase;
-      uint64_t addr_offset = (adjust_opcode / prologue->LineRange) *
-                             prologue->MinInstLength;
-      int32_t line_offset = prologue->LineBase +
-                            (adjust_opcode % prologue->LineRange);
-      state.Line += line_offset;
-      state.Address += addr_offset;
-      state.appendRowToMatrix(*offset_ptr);
+      uint8_t adjust_opcode = opcode - Prologue.OpcodeBase;
+      uint64_t addr_offset =
+          (adjust_opcode / Prologue.LineRange) * Prologue.MinInstLength;
+      int32_t line_offset =
+          Prologue.LineBase + (adjust_opcode % Prologue.LineRange);
+      State.Row.Line += line_offset;
+      State.Row.Address += addr_offset;
+      State.appendRowToMatrix(*offset_ptr);
     }
   }
 
-  state.finalize();
+  if (!State.Sequence.Empty) {
+    fprintf(stderr, "warning: last sequence in debug line table is not"
+                    "terminated!\n");
+  }
+
+  // Sort all sequences so that address lookup will work faster.
+  if (!Sequences.empty()) {
+    std::sort(Sequences.begin(), Sequences.end(), Sequence::orderByLowPC);
+    // Note: actually, instruction address ranges of sequences should not
+    // overlap (in shared objects and executables). If they do, the address
+    // lookup would still work, though, but result would be ambiguous.
+    // We don't report warning in this case. For example,
+    // sometimes .so compiled from multiple object files contains a few
+    // rudimentary sequences for address ranges [0x0, 0xsomething).
+  }
 
   return end_offset;
 }
diff --git a/lib/DebugInfo/DWARFDebugLine.h b/lib/DebugInfo/DWARFDebugLine.h
index ec73970f0f..0b3e267c2f 100644
--- a/lib/DebugInfo/DWARFDebugLine.h
+++ b/lib/DebugInfo/DWARFDebugLine.h
@@ -185,6 +185,10 @@ public:
     void dump(raw_ostream &OS) const;
     void clear();
 
+    /// Parse prologue and all rows.
+    bool parse(DataExtractor debug_line_data, const RelocAddrMap *RMap,
+               uint32_t *offset_ptr);
+
     struct Prologue Prologue;
     typedef std::vector<Row> RowVector;
     typedef RowVector::const_iterator RowIter;
@@ -194,46 +198,26 @@ public:
     SequenceVector Sequences;
   };
 
-  struct State : public Row, public Sequence, public LineTable {
-    // Special row codes.
-    enum {
-      StartParsingLineTable = 0,
-      DoneParsingLineTable = -1
-    };
-
-    State() : row(StartParsingLineTable) {}
-    virtual ~State();
-
-    virtual void appendRowToMatrix(uint32_t offset);
-    virtual void finalize();
-    virtual void reset() {
-      Row::reset(Prologue.DefaultIsStmt);
-      Sequence::reset();
-    }
-
-    // The row number that starts at zero for the prologue, and increases for
-    // each row added to the matrix.
-    unsigned row;
-  };
-
-  struct DumpingState : public State {
-    DumpingState(raw_ostream &OS) : OS(OS) {}
-    virtual ~DumpingState();
-    void finalize() override;
-  private:
-    raw_ostream &OS;
-  };
-
-  /// Parse a single line table (prologue and all rows).
-  static bool parseStatementTable(DataExtractor debug_line_data,
-                                  const RelocAddrMap *RMap,
-                                  uint32_t *offset_ptr, State &state);
-
   const LineTable *getLineTable(uint32_t offset) const;
   const LineTable *getOrParseLineTable(DataExtractor debug_line_data,
                                        uint32_t offset);
 
 private:
+  struct ParsingState {
+    ParsingState(struct LineTable *LT);
+
+    void resetRowAndSequence();
+    void appendRowToMatrix(uint32_t offset);
+
+    // Line table we're currently parsing.
+    struct LineTable *LineTable;
+    // The row number that starts at zero for the prologue, and increases for
+    // each row added to the matrix.
+    unsigned RowNumber;
+    struct Row Row;
+    struct Sequence Sequence;
+  };
+
   typedef std::map<uint32_t, LineTable> LineTableMapTy;
   typedef LineTableMapTy::iterator LineTableIter;
   typedef LineTableMapTy::const_iterator LineTableConstIter;