Adding Time Hooks for measuring semantics performance (#1131)

This PR introduces `hook_timer_start` and `hook_timer_stop`, which can
be used to measure the execution time of an instruction or an entire
semantics by getting the current timestamp when starting the timer and
then when stopping it, we get the current timestamp again, and save the
difference into a default file `hooks_time.txt` in the current
directory.

---------

Co-authored-by: Theodoros Kasampalis <[email protected]>

bin/llvm-kompile-clang

@@ -263,6 +263,7 @@ if $link; then
     "$LIBDIR"/libcollect.a
     "$LIBDIR"/libmeta.a
     "$LIBDIR"/libjson.a
+    "$LIBDIR"/libtimer.a
   )
 
   components=(

include/runtime/timer.h

@@ -0,0 +1,25 @@
+#ifndef TIMER_H
+#define TIMER_H
+
+#include <chrono>
+
+// Macro to register a new timer.
+// Timers are implemented using the std::chrono::high_resolution_clock.
+// The unit should be one of the duration types provided in std::chrono,
+// e.g. seconds, microseconds, etc.
+#define REGISTER_TIMER(name, unit)                                             \
+  static std::chrono::high_resolution_clock::time_point name##_clock_start;    \
+  static std::chrono::high_resolution_clock::time_point name##_clock_stop;     \
+  void name##_timer_start() {                                                  \
+    name##_clock_start = std::chrono::high_resolution_clock::now();            \
+  }                                                                            \
+  void name##_timer_stop() {                                                   \
+    name##_clock_stop = std::chrono::high_resolution_clock::now();             \
+  }                                                                            \
+  uint64_t name##_timer_measurement() {                                        \
+    return std::chrono::duration_cast<std::chrono::unit>(                      \
+               name##_clock_stop - name##_clock_start)                         \
+        .count();                                                              \
+  }
+
+#endif // TIMER_H

runtime/CMakeLists.txt

@@ -19,3 +19,4 @@ add_subdirectory(lto)
 add_subdirectory(meta)
 add_subdirectory(strings)
 add_subdirectory(util)
+add_subdirectory(timer)

runtime/timer/CMakeLists.txt

@@ -0,0 +1,8 @@
+add_library( timer STATIC
+  timer.cpp
+)
+
+install(
+  TARGETS timer
+  ARCHIVE DESTINATION lib/kllvm
+)

runtime/timer/timer.cpp

@@ -0,0 +1,25 @@
+#include <fstream>
+
+#include "runtime/header.h"
+#include "runtime/timer.h"
+
+REGISTER_TIMER(hook, nanoseconds);
+
+extern "C" {
+
+block *hook_TIMER_timerStart(void) {
+  hook_timer_start();
+
+  return dot_k();
+}
+
+block *hook_TIMER_timerStop(void) {
+  hook_timer_stop();
+
+  std::ofstream times_file;
+  times_file.open("hook_times.txt", std::ios_base::app);
+  times_file << hook_timer_measurement() << std::endl;
+
+  return dot_k();
+}
+}