Tutorial: Debugging with Intel® Distribution for GDB*

The multi-target feature enables debugging of multiple targets in a single debugging session.

With this feature, you can define breakpoints inside and outside the kernel to debug the host portion of the program. For example, define two breakpoints and run the target as follows:

1. break 56

   Expected output:

   Breakpoint 1 at 0x405800: file /path/to/array-transform.cpp, line 56.

2. break 83

   Expected output:

   Breakpoint 2 at 0x403e13: file /path/to/array-transform.cpp, line 83.

3. run gpu

   Expected output:

   [...]
   [Switching to Thread 1.129 lane 1]
   
   Thread 2.129 hit Breakpoint 1, with SIMD lanes [0-7], main::{lambda(auto:1&)#1}::operator()[...] at array-transform.cpp:56
   56          int element = in[index];  // breakpoint-here

Now you are inside the kernel (in this case, the kernel is running on the GPU). The context is Thread 2.129, lane 0.

Disable the breakpoint at line 56 and continue:

disable 1

continue

Expected output:

Continuing.
[Switching to Thread 0x7ffff7fd9780 (LWP 19604)]


Thread 1.1 "array-transform" hit Breakpoint 2, main (...)
  at /path/to/array-transform.cpp:83
83    cout << "success; result is correct.\n";

Try executing print input and print output as follows:

• print input[6]

  Expected output:

  $1 = 106

• print output[6]

  Expected output:

  $2 = 206

This time the stop event is received from the host. The context is automatically switched to Thread 1.1. You can investigate the host-side values as shown above.