Low-level Debugger

       
Company
   Academic Project		     Engine
   N/A
Platform
   Windows PC		     Skills
   C++
Role
   Tool Engineer		     Responsibilities
   Implementing easy-interpolating debuggers

Features

  • Crash handler
  • Memory debugger
  • Instrumented profiler

Crash Handler

It creates a dump file when an app is accidentally crashed. Using the dump file, It operates without the presence of a debugger and provides some form of debugging information (Mini Dump) that can be later analyzed with a debugger.

Memory Debugger

It records useful information in the event of heap related bugs. It detects the following heap related bugs and incorrect usages: memory leak, buffer read and write overflow, buffer read and writes after delete, double news, double deletes, mismatched new/delete[], deleting a non-heap allocated pointer.

Instrumented Profiler

The above image is a capture of what my profiler analyzed some fraction of Box2D. The type of the profiler I made is a manual instrumented profiler which is a method of manually injecting sections of code that is responsible to write out trace information.
It records the following data: function name, hit count, percents per func, sec per func, inclusive cycles, exclusive cycles, max recursion count.

Measuring super-accurate time is quite challenging in C++. Although __rdtsc (clock cycles) is primarily used in this profiler, it is, to be honest, not a good idea because OS scheduler could reschedule other threads, processes at arbitrary moments, or slow down the clock.

However, I believe using __rdtsc is enough for my academic purpose which is focused on making structure and understanding how a profiler is working on. To convert clock cycles to a human-understanding format (seconds), sleep_for is used as the following code is written:

Profiler::Profiler() {
 ...
 // Measure the speed of this processor
 uint64 cyclesMeasureStart = __rdtsc();
 // 100ms = 0.1s
 std::this_thread::sleep_for(std::chrono::milliseconds(100));
 uint64 cyclesMeasureEnd = __rdtsc();
 m_CyclesPerSec = cyclesMeasureEnd - cyclesMeasureStart;
}

void Profiler::PrintInfoToCSV(...) {
 ...
 // exclusiveClock is a number of clock cycles by __rdtsc
 // m_CyclesPerSec * 10.f = 1s
 float exclusiveSec = exclusiveClock / (m_CyclesPerSec * 10.f);
 ...
}

Sorce Code