[libcxx] [llvm] [lld] [libc] [flang] [clang-tools-extra] [clang] [compiler-rt] [libcxxabi] [CSSPGO] Compute and report post-match profile staleness (PR #79090)

[via cfe-commits]

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@@ -433,6 +433,44 @@ using CandidateQueue =
     PriorityQueue<InlineCandidate, std::vector<InlineCandidate>,
                   CandidateComparer>;
 
+// Profile matching statstics.
+class ProfileMatchStats {
+  const Module &M;
+  SampleProfileReader &Reader;
+  const PseudoProbeManager *ProbeManager;
+
+public:
+  ProfileMatchStats(const Module &M, SampleProfileReader &Reader,
+                    const PseudoProbeManager *ProbeManager)
+      : M(M), Reader(Reader), ProbeManager(ProbeManager) {}
+
+  uint64_t NumMismatchedCallsites = 0;
+  uint64_t TotalProfiledCallsites = 0;
+  uint64_t MismatchedCallsiteSamples = 0;
+  uint64_t NumMismatchedFuncHash = 0;
+  uint64_t TotalProfiledFunc = 0;
+  uint64_t MismatchedFuncHashSamples = 0;
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WenleiHe wrote:

This is really just `MismatchedFunctionSamples`, in contrast to `TotalFunctionSamples`.
I know this isn't changed in this patch, but why did we use the term `FuncHashSamples`? 

https://github.com/llvm/llvm-project/pull/79090