[llvm] [memprof] Use CallStackRadixTreeBuilder in the V3 format (PR #94708)

[Teresa Johnson via llvm-commits]

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@@ -900,9 +900,17 @@ struct LinearCallStackIdConverter {
     Frames.reserve(NumFrames);
     for (; NumFrames; --NumFrames) {
       LinearFrameId Elem =
-          support::endian::readNext<LinearFrameId, llvm::endianness::little>(
-              Ptr);
+          support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
+      // Follow a pointer to the parent, if any.
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teresajohnson wrote:

Maybe point to the comment block further down that describes the radix tree format.

https://github.com/llvm/llvm-project/pull/94708