[NFC][DebugInfo] Wrap DILineInfo return type with std::optional to handle missing debug info. (#129792)

Currently, `DIContext::getLineInfoForAddress` and
`DIContext::getLineInfoForDataAddress` returns empty DILineInfo when the
debug info is missing for the given address. This is not differentiable
with the case when debug info is found for the given address but the
debug info is default value (filename:linenum is <invalid>:0).

This change wraps the return types of `DIContext::getLineInfoForAddress`
and `DIContext::getLineInfoForDataAddress` with `std::optional`.

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index f099bf5..82dda93 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -565,9 +565,13 @@ static bool lookup(ObjectFile &Obj, DWARFContext &DICtx, uint64_t Address,
 
   // TODO: it is neccessary to set proper SectionIndex here.
   // object::SectionedAddress::UndefSection works for only absolute addresses.
-  if (DILineInfo LineInfo = DICtx.getLineInfoForAddress(
-          {Lookup, object::SectionedAddress::UndefSection}))
+  if (DILineInfo LineInfo =
+          DICtx
+              .getLineInfoForAddress(
+                  {Lookup, object::SectionedAddress::UndefSection})
+              .value_or(DILineInfo())) {
     LineInfo.dump(OS);
+  }
 
   return true;
 }