[clang] [Clang] Optimize some `getBeginLoc` implementations (PR #141058)

[Younan Zhang via cfe-commits]

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@@ -296,14 +298,18 @@ class NestedNameSpecifierLoc {
   /// Retrieve the location of the beginning of this
   /// nested-name-specifier.
   SourceLocation getBeginLoc() const {
-    return getSourceRange().getBegin();
+    if (!Qualifier)
+      return SourceLocation();
+
+    NestedNameSpecifierLoc First = *this;
+    while (NestedNameSpecifierLoc Prefix = First.getPrefix())
+      First = Prefix;
+    return First.getLocalSourceRange().getBegin();
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zyn0217 wrote:

I didn't see the differences of changes on these functions... Are they related?

https://github.com/llvm/llvm-project/pull/141058