Since we can already track allocations, we can diagnose memory faults to
some degree. If the fault happens in a prior allocation (use after free)
or "close but outside" one, we can provide that information to the user.
Note that the fault address might be page aligned, and not all accesses
trigger a fault, especially for allocations that are backed by a
MemoryManager. Still, if people disable the MemoryManager or the
allocation is big enough, we can sometimes provide valueable feedback.
The kernel names for OpenMP are manually mangled and not ideal when we
report something to the user. We demangle them now, providing the
function and line number of the target region, together with the actual
kernel name.
Similar to (de)allocation traces, we can record kernel launch stack
traces and display them in case of an error. However, the AMD GPU plugin
signal handler, which is invoked on memroy faults, cannot pinpoint the
offending kernel. Insteade print `<NUM>`, set via
`OFFLOAD_TRACK_NUM_KERNEL_LAUNCH_TRACES=<NUM>`, many traces. The
recoding/record uses a ring buffer of fixed size (for now 8).
For `trap` errors, we print the actual kernel name, and trace if
recorded.
As a first step towards a GPU sanitizer we now can track allocations and
deallocations in order to report double frees, and other problems during
deallocation.
