Return discriminator in DWARF Info

[sque]

Summary

This change does two things:

1. Adds a "Discriminator" field to struct DILineInfo, which defaults to 0.
2. Fills out the "Discriminator" field in DILineInfo in DWARFDebugLine::LineTable::getFileLineInfoForAddress(). The discriminator value is already present in the internal DWARF data.

[echristo]

One nit then OK. I tried to come up with a way to keep the routines fairly neutral here and couldn't come up with an easy one that didn't involve a lot more refactoring than seems necessary if we just want the discriminator and there aren't any other users with special information.

Thanks!

-eric

include/llvm/DebugInfo/DIContext.h

37

A discriminator isn't format neutral so we'll probably want to start a "format specific information" set in DILineInfo.

This could probably use a comment of the sort:

// Used in DWARF line tables blah blah blah

[sque]

I added a comment explaining that the field is DWARF-specific. If new format-specific fields are added in the future, it can be put under that section for DWARF or under a new section for other formats.

include/llvm/DebugInfo/DIContext.h

   std::string FunctionName;
   uint32_t Line;
   uint32_t Column;
+  uint32_t Discriminator;
 
   DILineInfo()
-      : FileName("<invalid>"), FunctionName("<invalid>"), Line(0), Column(0) {}
+      : FileName("<invalid>"), FunctionName("<invalid>"), Line(0), Column(0),
+        Discriminator(0) {}
 
   bool operator==(const DILineInfo &RHS) const {
     return Line == RHS.Line && Column == RHS.Column &&

lib/DebugInfo/DWARF/DWARFDebugLine.cpp

     return false;
   Result.Line = Row.Line;
   Result.Column = Row.Column;
+  Result.Discriminator = Row.Discriminator;
   return true;
 }