[llvm-cov] Improve error messaging for function mismatches

Passing "-dump" to llvm-cov will now print more detailed information
about function hash and counter mismatches. This should make it easier
to debug *.profdata files which contain incorrect records, and to debug
other scenarios where coverage goes missing due to mismatch issues.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313853 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 1 deletions

diff --git a/tools/llvm-cov/CodeCoverage.cpp b/tools/llvm-cov/CodeCoverage.cpp
index 09ee82a491e..981c93a2d95 100644
--- a/tools/llvm-cov/CodeCoverage.cpp
+++ b/tools/llvm-cov/CodeCoverage.cpp
@@ -350,9 +350,23 @@ std::unique_ptr<CoverageMapping> CodeCoverageTool::load() {
   }
   auto Coverage = std::move(CoverageOrErr.get());
   unsigned Mismatched = Coverage->getMismatchedCount();
-  if (Mismatched)
+  if (Mismatched) {
     warning(utostr(Mismatched) + " functions have mismatched data");
 
+    if (ViewOpts.Debug) {
+      for (const auto &HashMismatch : Coverage->getHashMismatches())
+        errs() << "hash-mismatch: "
+               << "No profile record found for '" << HashMismatch.first << "'"
+               << " with hash = 0x" << utohexstr(HashMismatch.second) << "\n";
+
+      for (const auto &CounterMismatch : Coverage->getCounterMismatches())
+        errs() << "counter-mismatch: "
+               << "Coverage mapping for " << CounterMismatch.first
+               << " only has " << CounterMismatch.second
+               << " valid counter expressions\n";
+    }
+  }
+
   remapPathNames(*Coverage);
 
   if (!SourceFiles.empty())