[PERF2BOLT] Improve file matching

Summary:
If the input binary for perf2bolt has a build-id and perf data has
recorded build-ids, then try to match them. Adjust the file name if
build-ids match to cover cases where the binary was renamed after data
collection. If there's no matching build-id report an error and exit.

While scanning task events, truncate the name to 15 characters prior to
matching, since that's how names are reported by perf.

(cherry picked from FBD8034436)

bolt/src/DataAggregator.cpp

@@ -35,16 +35,22 @@ namespace opts {
 
 extern cl::OptionCategory AggregatorCategory;
 
-static llvm::cl::opt<bool>
-TimeAggregator("time-aggr",
-  cl::desc("time BOLT aggregator"),
+static cl::opt<bool>
+BasicAggregation("nl",
+  cl::desc("aggregate basic samples (without LBR info)"),
   cl::init(false),
   cl::ZeroOrMore,
   cl::cat(AggregatorCategory));
 
-static llvm::cl::opt<bool>
-BasicAggregation("nl",
-  cl::desc("aggregate basic samples (without LBR info)"),
+static cl::opt<bool>
+IgnoreBuildID("ignore-build-id",
+  cl::desc("continue even if build-ids in input binary and perf.data mismatch"),
+  cl::init(false),
+  cl::cat(AggregatorCategory));
+
+static cl::opt<bool>
+TimeAggregator("time-aggr",
+  cl::desc("time BOLT aggregator"),
   cl::init(false),
   cl::ZeroOrMore,
   cl::cat(AggregatorCategory));
@@ -219,7 +225,7 @@ bool DataAggregator::launchPerfTasksNoWait() {
   return true;
 }
 
-Optional<std::string> DataAggregator::getPerfBuildID() {
+void DataAggregator::processFileBuildID(StringRef FileBuildID) {
   SmallVector<const char *, 4> Argv;
   SmallVector<char, 256> OutputPath;
   SmallVector<char, 256> ErrPath;
@@ -265,7 +271,7 @@ Optional<std::string> DataAggregator::getPerfBuildID() {
     errs() << ErrBuf;
     deleteTempFile(ErrPath.data());
     deleteTempFile(OutputPath.data());
-    return NoneType();
+    return;
   }
 
   ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
@@ -275,26 +281,44 @@ Optional<std::string> DataAggregator::getPerfBuildID() {
            << EC.message() << "\n";
     deleteTempFile(ErrPath.data());
     deleteTempFile(OutputPath.data());
-    return NoneType();
+    return;
   }
 
   FileBuf.reset(MB->release());
   ParsingBuf = FileBuf->getBuffer();
-  Col = 0;
-  Line = 1;
-  auto ParseResult = parsePerfBuildID();
-  if (!ParseResult) {
-    outs() << "PERF2BOLT: Failed to parse build-id from perf output\n";
+  if (ParsingBuf.empty()) {
+    errs() << "PERF2BOLT-WARNING: build-id will not be checked because perf "
+              "data was recorded without it\n";
     deleteTempFile(ErrPath.data());
     deleteTempFile(OutputPath.data());
-    return NoneType();
+    return;
   }
 
-  outs() << "PERF2BOLT: Perf.data build-id is:  " << *ParseResult << "\n";
+  Col = 0;
+  Line = 1;
+  auto FileName = getFileNameForBuildID(FileBuildID);
+  if (!FileName) {
+    errs() << "PERF2BOLT-ERROR: failed to match build-id from perf output. "
+              "This indicates the input binary supplied for data aggregation "
+              "is not the same recorded by perf when collecting profiling "
+              "data. Use -ignore-build-id option to override.\n";
+    if (!opts::IgnoreBuildID) {
+      deleteTempFile(ErrPath.data());
+      deleteTempFile(OutputPath.data());
+      abort();
+      exit(1);
+    }
+  } else if (*FileName != BinaryName) {
+    errs() << "PERF2BOLT-WARNING: build-id matched a different file name. "
+              "Using \"" << *FileName << "\" for profile parsing.\n";
+    BinaryName = *FileName;
+  } else {
+    outs() << "PERF2BOLT: matched build-id and file name\n";
+  }
 
   deleteTempFile(ErrPath.data());
   deleteTempFile(OutputPath.data());
-  return std::string(ParseResult->data(), ParseResult->size());
+  return;
 }
 
 bool DataAggregator::checkPerfDataMagic(StringRef FileName) {
@@ -967,7 +991,7 @@ ErrorOr<int64_t> DataAggregator::parseTaskPID() {
   auto CommNameStr = parseString(FieldSeparator, true);
   if (std::error_code EC = CommNameStr.getError())
     return EC;
-  if (CommNameStr.get() != BinaryName) {
+  if (CommNameStr.get() != BinaryName.substr(0, 15)) {
     consumeRestOfLine();
     return -1;
   }
@@ -1013,12 +1037,19 @@ std::error_code DataAggregator::parseTasks() {
 
     PIDs.insert(PID);
   }
-  if (!PIDs.empty())
+  if (!PIDs.empty()) {
     outs() << "PERF2BOLT: Input binary is associated with " << PIDs.size()
            << " PID(s)\n";
-  else
-    outs() << "PERF2BOLT: Could not bind input binary to a PID - will parse "
-              "all samples in perf data.\n";
+  } else {
+    if (errs().has_colors())
+      errs().changeColor(raw_ostream::YELLOW);
+    errs() << "PERF2BOLT-WARNING: Could not bind input binary to a PID - will "
+              "parse all samples in perf data. This could result in corrupted "
+              "samples for the input binary if system-wide profile collection "
+              "was used.\n";
+    if (errs().has_colors())
+      errs().resetColor();
+  }
 
   return std::error_code();
 }
@@ -1039,16 +1070,15 @@ DataAggregator::parseNameBuildIDPair() {
   return std::make_pair(NameStr.get(), BuildIDStr.get());
 }
 
-Optional<StringRef> DataAggregator::parsePerfBuildID() {
+Optional<StringRef>
+DataAggregator::getFileNameForBuildID(StringRef FileBuildID) {
   while (hasData()) {
     auto IDPair = parseNameBuildIDPair();
     if (!IDPair)
       return NoneType();
 
-    if (sys::path::filename(IDPair->first) != BinaryName)
-      continue;
-
-    return IDPair->second;
+    if (IDPair->second == FileBuildID)
+      return sys::path::filename(IDPair->first);
   }
   return NoneType();
 }

bolt/src/DataAggregator.h

@@ -85,7 +85,7 @@ class DataAggregator : public DataReader {
   StringRef OutputFDataName;
 
   /// Our sampled binary name to look for in perf.data
-  StringRef BinaryName;
+  std::string BinaryName;
 
   DenseSet<int64_t> PIDs;
 
@@ -189,9 +189,9 @@ class DataAggregator : public DataReader {
   /// Parse a single pair of binary full path and associated build-id
   Optional<std::pair<StringRef, StringRef>> parseNameBuildIDPair();
 
-  /// Parse the output generated by perf buildid-list to extract the build-id
-  /// of the binary used when collecting profiling
-  Optional<StringRef> parsePerfBuildID();
+  /// Parse the output generated by "perf buildid-list" to extract build-ids
+  /// and return a file name matching a given \p FileBuildID.
+  Optional<StringRef> getFileNameForBuildID(StringRef FileBuildID);
 
 public:
   DataAggregator(raw_ostream &Diag, StringRef BinaryName)
@@ -221,11 +221,13 @@ public:
   /// Check whether \p FileName is a perf.data file
   static bool checkPerfDataMagic(StringRef FileName);
 
-  /// Launch a subprocess with perf buildid-list to extract the build-id of the
-  /// binary used when collecting profiling. Different than launchPerf*, this
-  /// one spawns the subprocess and blocks. Then it parses the result and
-  /// returns the build-id.
-  Optional<std::string> getPerfBuildID();
+  /// If we have a build-id available for the input file, use it to assist
+  /// matching profile to a binary.
+  ///
+  /// If the binary name changed after profile collection, use build-id
+  /// to get the proper name in perf data when build-ids are available.
+  /// If \p FileBuildID has no match, then issue an error and exit.
+  void processFileBuildID(StringRef FileBuildID);
 
   /// Debugging dump methods
   void dump() const;

bolt/src/RewriteInstance.cpp

@@ -370,12 +370,6 @@ DiffOnly("diff-only",
   cl::Hidden,
   cl::cat(BoltDiffCategory));
 
-static cl::opt<bool>
-IgnoreBuildID("ignore-build-id",
-  cl::desc("continue even if build-ids in input binary and perf.data mismatch"),
-  cl::init(false),
-  cl::cat(AggregatorCategory));
-
 static cl::opt<bool>
 TimeRewrite("time-rewrite",
   cl::desc("print time spent in rewriting passes"),
@@ -950,38 +944,12 @@ RewriteInstance::getBuildID() const {
       OS << Twine::utohexstr(*CharIter);
       ++CharIter;
     }
-    outs() << "BOLT-INFO: Binary build-id is:     " << OS.str() << "\n";
+    outs() << "BOLT-INFO: binary build-id is:     " << OS.str() << "\n";
     return OS.str();
   }
   return NoneType();
 }
 
-void RewriteInstance::checkBuildID() {
-  auto FileBuildID = getBuildID();
-  if (!FileBuildID) {
-    outs() << "BOLT-WARNING: Build ID will not be checked because we could not "
-              "read one from input binary\n";
-    return;
-  }
-  auto PerfBuildID = DA.getPerfBuildID();
-  if (!PerfBuildID) {
-    outs() << "BOLT-WARNING: Build ID will not be checked because we could not "
-              "read one from perf.data\n";
-    return;
-  }
-  if (*FileBuildID == *PerfBuildID)
-    return;
-
-  outs() << "BOLT-ERROR: Build ID mismatch! This indicates the input binary "
-            "supplied for data aggregation is not the same recorded by perf "
-            "when collecting profiling data.\n";
-
-  if (!opts::IgnoreBuildID) {
-    DA.abort();
-    exit(1);
-  }
-}
-
 void RewriteInstance::run() {
   if (!BC) {
     errs() << "BOLT-ERROR: failed to create a binary context\n";
@@ -1015,8 +983,15 @@ void RewriteInstance::run() {
                 (llvm::Triple::ArchType)InputFile->getArch())
          << "\n";
 
-  if (DA.started())
-    checkBuildID();
+  if (DA.started()) {
+    if (auto FileBuildID = getBuildID()) {
+      DA.processFileBuildID(*FileBuildID);
+    } else {
+      errs() << "BOLT-WARNING: build-id will not be checked because we could "
+                "not read one from input binary\n";
+    }
+  }
+
   unsigned PassNumber = 1;
   executeRewritePass({});
   if (opts::AggregateOnly || opts::DiffOnly)

bolt/src/RewriteInstance.h

@@ -121,10 +121,6 @@ public:
   /// Run all the necessary steps to read, optimize and rewrite the binary.
   void run();
 
-  /// Check that binary build ID matches the one used in perf.data to collect
-  /// profile
-  void checkBuildID();
-
   /// Diff this instance against another one. Non-const since we may run passes
   /// to fold identical functions.
   void compare(RewriteInstance &RI2);