It was previously not possible for tools to use solely the stackmap information emitted to reconstruct the return addresses of callsites in the map, which is necessary to use the information to walk a stack. This patch adds per-function callsite counts when emitting the stackmap section in order to resolve the problem. Note that this slightly alters the stackmap format, so external tools parsing these maps will need to be updated.
Records only store their offset from the beginning of the function they belong to. While these records and the functions are output in program order, it is not possible to determine where the end of one function's records are without the callsite count when processing the records to compute return addresses.