[llvm] [llvm-profgen] Add branch/target validation (PR #188620)

[Amir Ayupov via llvm-commits]

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@@ -1344,6 +1344,52 @@ void PerfScriptReader::warnInvalidRange() {
       "range end acrossing the unconditinal jmp.");
 }
 
+void PerfScriptReader::warnIfBranchTargetMismatch() {
+  // Collect unique branch source and target addresses from LBR samples,
+  // then check what percentage don't match known instructions in the binary.
+
+  uint64_t MismatchedBranches = 0;
+  uint64_t MismatchedIndirectTargets = 0;
+  uint64_t MismatchedTargets = 0;
+  uint64_t TotalSamples = 0;
+
+  for (const auto &Item : AggregatedSamples) {
+    const PerfSample *Sample = Item.first.getPtr();
+    for (const LBREntry &LBR : Sample->LBRStack) {
+      uint64_t Source = LBR.Source;
+      uint64_t Target = LBR.Target;
+      if (Source == ExternalAddr || Target == ExternalAddr)
+        continue;
+      TotalSamples++;
+
+      // Validate Branch sources are Call/Branch/Indirect Branch
+      if (!Binary->addressIsTransfer(Source))
+        MismatchedBranches++;
+
+      // Validate Indirect Branch targets landed in code. This may over estimate
+      // the vaid targets only because there's no good way to determine jump
+      // table targets
+      if (Binary->addressIsIndirectBranch(Source)) {
+        if (!Binary->addressIsCode(Target))
+          MismatchedIndirectTargets++;
+      } else if (!Binary->addressIsBranchTarget(Target) &&
+                 !Binary->findFuncRangeForStartAddr(Target))
+        MismatchedTargets++;
+    }
+  }
+
+  emitWarningSummary(MismatchedBranches, TotalSamples,
+                     "of branches do not match the binary, likely due to "
+                     "problematic raw samples or mismatch in binary.");
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aaupov wrote:

Please address the other sentence too

https://github.com/llvm/llvm-project/pull/188620