[llvm] [NFC] Add fragment-getting functions to DbgRecord (PR #97705)

[Stephen Tozer via llvm-commits]

================
@@ -460,6 +461,19 @@ class DbgVariableRecord : public DbgRecord, protected DebugValueUser {
     resetDebugValue(0, NewLocation);
   }
 
+  std::optional<DbgVariableFragmentInfo> getFragment() const;
+  /// Get the FragmentInfo for the variable if it exists, otherwise return a
+  /// FragmentInfo that covers the entire variable if the variable size is
+  /// known, otherwise return a zero-sized fragment.
+  DbgVariableFragmentInfo getFragmentOrEntireVariable() const {
+    DbgVariableFragmentInfo VariableSlice(0, 0);
+    // Get the fragment or variable size, or zero.
+    if (auto Sz = getFragmentSizeInBits())
+      VariableSlice.SizeInBits = *Sz;
+    if (auto Frag = getFragment())
+      VariableSlice.OffsetInBits = Frag->OffsetInBits;
+    return VariableSlice;
+  }
----------------
SLTozer wrote:

```suggestion
  DbgVariableFragmentInfo getFragmentOrEntireVariable() const {
    if (auto Frag = getFragment())
      return *Frag; 
    if (auto Sz = getVariable()->getSizeInBits())
      return {*Sz, 0};
    return {0, 0};
  }
```

YMMV, but personally I feel this style is better for using just simple returns; could also replace the last lines with just `return {getVariable()->getSizeInBits().value_or(0), };`, but personally I find the above easier to read.

https://github.com/llvm/llvm-project/pull/97705