Debug an Application on a CPU
This section describes a basic scenario of debugging a sample SYCL* app, Array Transform, with the kernel offloaded to the CPU.
Before you proceed, make sure you have completed all the necessary setup steps and got a sample code as described in the Get Started Guide.
Basic Debugging
52 h.parallel_for(data_range, [=](id<1> index) {
53 int id0 = GetDim(index, 0);
54 int element = in[index]; // breakpoint-here
55 int result = element + 50;
56 if (id0 % 2 == 0) {
57 result = result + 50; // then-branch
58 } else {
59 result = -1; // else-branch
60 }
61 out[index] = result;
62 });Set a breakpoint inside the kernel at line 54 marked as breakpoint-here in the array-transform.cpp file.
To run the application, on the Debug toolbar, click
Local Windows Debugger button.The program stops at the breakpoint.
Now you can investigate local variables, print a stack trace, and get information on threads by opening the corresponding windows from the Debug tab.
To investigate local variables, go to Debug > Windows > Locals.
To get information on threads, go to Debug > Windows > Threads.
To look into disassembly, go to Debug > Windows > Disassembly.
To investigate general purpose registers, go to Debug > Windows > Registers.
Limitations
Kernel Functions
Kernel functions that have a call-by-value parameter of a class/struct type (for example, cl::sycl::id) cannot be used in the Watch window.
Accessor’s Operator []
The operator [] of an accessor object cannot be used in the Watch window.