[compiler-rt] [ctxprof] Auto root detection: trie for stack samples (PR #133106)

[Snehasish Kumar via llvm-commits]

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@@ -0,0 +1,123 @@
+#include "../RootAutoDetector.h"
+#include "sanitizer_common/sanitizer_array_ref.h"
+#include "gtest/gtest.h"
+
+using namespace __ctx_profile;
+
+class MockCallsiteTree final : public PerThreadCallsiteTrie {
+  // Return the first multiple of 100.
+  uptr getFctStartAddr(uptr CallsiteAddress) const override {
+    return (CallsiteAddress / 100) * 100;
+  }
+};
+
+class Marker {
+  enum class Kind { End, Value, Split };
+  const uptr Value;
+  const Kind K;
+  Marker(uptr V, Kind S) : Value(V), K(S) {}
+
+public:
+  Marker(uptr V) : Marker(V, Kind::Value) {}
+
+  static Marker split(uptr V) { return Marker(V, Kind::Split); }
+  static Marker term() { return Marker(0, Kind::End); }
+
+  bool isSplit() const { return K == Kind::Split; }
+  bool isTerm() const { return K == Kind::End; }
+  bool isVal() const { return K == Kind::Value; }
+
+  bool operator==(const Marker &M) const {
+    return Value == M.Value && K == M.K;
+  }
+};
+
+void popAndCheck(ArrayRef<Marker> &Preorder, Marker M) {
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snehasish wrote:

nit: No need to take a reference to an ArrayRef. 
Same for the usage in other places.

https://github.com/llvm/llvm-project/pull/133106