[CSSPGO] Skip dangling probe value when computing profile summary

[wenlei]

Summary

Recently we switched to use InvalidProbeCount = UINT64_MAX (instead of 0) to represent dangling probe, but UINT64_MAX is not excluded when computing profile summary. This caused profile summary to produce incorrect hot/cold threshold. The change fixed it by excluding UINT64_MAX from summary builder.

[hoy]

LGTM, thanks!

[wlei]

lgtm, thanks!

llvm/lib/ProfileData/ProfileSummaryBuilder.cpp

 // equivalent to a block with a count in the instrumented profile.
 void SampleProfileSummaryBuilder::addRecord(
     const sampleprof::FunctionSamples &FS, bool isCallsiteSample) {
   if (!isCallsiteSample) {
     NumFunctions++;
     if (FS.getHeadSamples() > MaxFunctionCount)
       MaxFunctionCount = FS.getHeadSamples();
   }
-  for (const auto &I : FS.getBodySamples())
-    addCount(I.second.getSamples());
+  for (const auto &I : FS.getBodySamples()) {
+    uint64_t Count = I.second.getSamples();
+    if (!sampleprof::FunctionSamples::ProfileIsProbeBased ||
+        (Count != sampleprof::FunctionSamples::InvalidProbeCount))
+      addCount(Count);
+  }
   for (const auto &I : FS.getCallsiteSamples())
     for (const auto &CS : I.second)
       addRecord(CS.second, true);
 }
 
 // The argument to this method is a vector of cutoff percentages and the return
 // value is a vector of (Cutoff, MinCount, NumCounts) triplets.
 void ProfileSummaryBuilder::computeDetailedSummary() {