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 ↗

(On Diff #80990)

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.

llvm/trunk/include/llvm/DebugInfo/DIContext.h

 
 /// DILineInfo - a format-neutral container for source line information.
 struct DILineInfo {
   std::string FileName;
   std::string FunctionName;
   uint32_t Line;
   uint32_t Column;
 
+  // DWARF-specific.
+  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 &&
            FileName == RHS.FileName && FunctionName == RHS.FunctionName;
   }
   bool operator!=(const DILineInfo &RHS) const {
     return !(*this == RHS);
   }

llvm/trunk/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

bool DWARFDebugLine::LineTable::getFileLineInfoForAddress(
   if (RowIndex == -1U)
     return false;
   // Take file number and line/column from the row.
   const auto &Row = Rows[RowIndex];
   if (!getFileNameByIndex(Row.File, CompDir, Kind, Result.FileName))
     return false;
   Result.Line = Row.Line;
   Result.Column = Row.Column;
+  Result.Discriminator = Row.Discriminator;
   return true;
 }