Add maximum_operations_per_instruction to DWARFDebugLine.

[endlessroad]

Summary

"maximum_operations_per_instruction" is a field that was added to .debug_line header in DWARF4.

[jasonmolenda]

Looks good; one small suggestion, otherwise please commit.

source/Plugins/SymbolFile/DWARF/DWARFDebugLine.cpp

427

Please add an else block here and assign a value of 1 to maximum_operations_per_instruction. If anyone uses this in the line table parser (unlikely unless we're adding Itanium support or something), we should avoid having a garbage value for older DWARF files.

[endlessroad]

Address Jason's comment

[tfiala]

Thanks, Jason!

Just running a few tests over here. If it comes up clean, I'll get it in.

[tfiala]

Passed tests on Ubuntu Linux and MacOSX.

[tfiala]

$ svn commit
Sending        source/Plugins/SymbolFile/DWARF/DWARFDebugLine.cpp
Sending        source/Plugins/SymbolFile/DWARF/DWARFDebugLine.h
Transmitting file data ..
Committed revision 218641.

source/Plugins/SymbolFile/DWARF/DWARFDebugLine.h

         uint16_t    version;        // Version identifier for the statement information format.
         uint32_t    prologue_length;// The number of bytes following the prologue_length field to the beginning of the first byte of the statement program itself.
         uint8_t     min_inst_length;// The size in bytes of the smallest target machine instruction. Statement program opcodes that alter the address register first multiply their operands by this value.
+        uint8_t     maximum_operations_per_instruction; // New in DWARF4. The maximum number of individual operations that may be encoded in an instruction.
         uint8_t     default_is_stmt;// The initial value of theis_stmtregister.
         int8_t      line_base;      // This parameter affects the meaning of the special opcodes. See below.
         uint8_t     line_range;     // This parameter affects the meaning of the special opcodes. See below.

source/Plugins/SymbolFile/DWARF/DWARFDebugLine.cpp

     prologue->prologue_length   = debug_line_data.GetDWARFOffset(offset_ptr);
     const lldb::offset_t end_prologue_offset = prologue->prologue_length + *offset_ptr;
     prologue->min_inst_length   = debug_line_data.GetU8(offset_ptr);
+    if (prologue->version >= 4)
+        prologue->maximum_operations_per_instruction = debug_line_data.GetU8(offset_ptr);
+    else
+        prologue->maximum_operations_per_instruction = 1;
     prologue->default_is_stmt   = debug_line_data.GetU8(offset_ptr);
     prologue->line_base         = debug_line_data.GetU8(offset_ptr);
     prologue->line_range        = debug_line_data.GetU8(offset_ptr);

       return false;
 
     const dw_offset_t end_prologue_offset = debug_line_data.GetDWARFOffset(&offset) + offset;
-    // Skip instruction length, default is stmt, line base, line range and
-    // opcode base, and all opcode lengths
+    // Skip instruction length, default is stmt, line base, line range
     offset += 4;
+    // For DWARF4, skip maximum operations per instruction
+    if (version >= 4)
+        offset += 1;
+    // Skip opcode base, and all opcode lengths
     const uint8_t opcode_base = debug_line_data.GetU8(&offset);
     offset += opcode_base - 1;
     std::vector<std::string> include_directories;