[llvm] [llvm-profgen] Add support for Linux kenrel profile (PR #92831)

[Lei Wang via llvm-commits]

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@@ -355,57 +355,69 @@ PerfReaderBase::create(ProfiledBinary *Binary, PerfInputFile &PerfInput,
 PerfInputFile
 PerfScriptReader::convertPerfDataToTrace(ProfiledBinary *Binary,
                                          PerfInputFile &File,
-                                         std::optional<uint32_t> PIDFilter) {
+                                         std::optional<int32_t> PIDFilter) {
   StringRef PerfData = File.InputFile;
   // Run perf script to retrieve PIDs matching binary we're interested in.
   auto PerfExecutable = sys::Process::FindInEnvPath("PATH", "perf");
   if (!PerfExecutable) {
     exitWithError("Perf not found.");
   }
   std::string PerfPath = *PerfExecutable;
-
   SmallString<128> PerfTraceFile;
   sys::fs::createUniquePath("perf-script-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%.tmp",
                             PerfTraceFile, /*MakeAbsolute=*/true);
   std::string ErrorFile = std::string(PerfTraceFile) + ".err";
-  StringRef ScriptMMapArgs[] = {PerfPath, "script",   "--show-mmap-events",
-                                "-F",     "comm,pid", "-i",
-                                PerfData};
   std::optional<StringRef> Redirects[] = {std::nullopt,             // Stdin
                                           StringRef(PerfTraceFile), // Stdout
                                           StringRef(ErrorFile)};    // Stderr
-  sys::ExecuteAndWait(PerfPath, ScriptMMapArgs, std::nullopt, Redirects);
-
   PerfScriptReader::TempFileCleanups.emplace_back(PerfTraceFile);
   PerfScriptReader::TempFileCleanups.emplace_back(ErrorFile);
 
-  // Collect the PIDs
-  TraceStream TraceIt(PerfTraceFile);
+  // For a kernel perf file, we assume --branch_filter=k is used. So there is
+  // no need for PIDs.
   std::string PIDs;
-  std::unordered_set<uint32_t> PIDSet;
-  while (!TraceIt.isAtEoF()) {
-    MMapEvent MMap;
-    if (isMMap2Event(TraceIt.getCurrentLine()) &&
-        extractMMap2EventForBinary(Binary, TraceIt.getCurrentLine(), MMap)) {
-      auto It = PIDSet.emplace(MMap.PID);
-      if (It.second && (!PIDFilter || MMap.PID == *PIDFilter)) {
-        if (!PIDs.empty()) {
-          PIDs.append(",");
+  if (!Binary->isKernel()) {
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wlei-llvm wrote:

How about making this a function parameter and pass it from the caller? thinking this may be useful for other binary to skip the PID passing.  

https://github.com/llvm/llvm-project/pull/92831