1 files changed, 61 insertions, 0 deletions
diff --git a/lib/esan/esan_sideline.h b/lib/esan/esan_sideline.h
new file mode 100644
index 000000000000..aa3fae1db318
--- /dev/null
+++ b/lib/esan/esan_sideline.h
@@ -0,0 +1,61 @@
+//===-- esan_sideline.h -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of EfficiencySanitizer, a family of performance tuners.
+//
+// Esan sideline thread support.
+//===----------------------------------------------------------------------===//
+
+#ifndef ESAN_SIDELINE_H
+#define ESAN_SIDELINE_H
+
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_internal_defs.h"
+
+namespace __esan {
+
+typedef void (*SidelineFunc)(void *Arg);
+
+// Currently only one sideline thread is supported.
+// It calls the SidelineFunc passed to launchThread once on each sample at the
+// given frequency in real time (i.e., wall clock time).
+class SidelineThread {
+public:
+  // We cannot initialize any fields in the constructor as it will be called
+  // *after* launchThread for a static instance, as esan.module_ctor is called
+  // before static initializers.
+  SidelineThread() {}
+  ~SidelineThread() {}
+
+  // To simplify declaration in sanitizer code where we want to avoid
+  // heap allocations, the constructor and destructor do nothing and
+  // launchThread and joinThread do the real work.
+  // They should each be called just once.
+  bool launchThread(SidelineFunc takeSample, void *Arg, u32 FreqMilliSec);
+  bool joinThread();
+
+  // Must be called from the sideline thread itself.
+  bool adjustTimer(u32 FreqMilliSec);
+
+private:
+  static int runSideline(void *Arg);
+  static void registerSignal(int SigNum);
+  static void handleSidelineSignal(int SigNum, void *SigInfo, void *Ctx);
+
+  char *Stack;
+  SidelineFunc sampleFunc;
+  void *FuncArg;
+  u32 Freq;
+  uptr SidelineId;
+  atomic_uintptr_t SidelineExit;
+};
+
+} // namespace __esan
+
+#endif  // ESAN_SIDELINE_H