Debugging
This section provides information about useful techniques and tools to find and resolve bugs while migrating your applications to NVIDIA Grace.
Sanitizers
The compiler might generate code and layout data that is slightly differently on Arm64 than on an x86 system, and this could expose latent memory bugs that were previously hidden. On GCC, the easiest way to look for these bugs is to compile with the memory sanitizers by adding the following to the standard compiler flags:
CFLAGS += -fsanitize=address -fsanitize=undefined
LDFLAGS += -fsanitize=address -fsanitize=undefined
Run the resulting binary, and bugs that are detected by the sanitizers will cause the program to exit immediately and print helpful stack traces and other information.
Memory Ordering
Arm is weakly ordered, like POWER and other modern architectures, and x86 is a variant of total-store-ordering (TSO). Code that relies on TSO might lack barriers to properly order memory references. Arm64 systems are weakly ordered multi-copy-atomic.
Although TSO allows reads to occur out-of-order with writes, and a processor to observe its own write before it is visible to others, the Armv8 memory model provides additional relaxations for performance and power efficiency. Code relying on pthread mutexes or locking abstractions found in C++, Java or other languages should not notice any difference. Code that has a bespoke implementation of lockless data structures, or implements its own synchronization primitives, will have to use the proper intrinsics and barriers to correctly order memory transactions (refer to Locks, Synchronization, and Atomics for more information).