In no-naked-pointers mode, recognize and skip code pointers present in
the stack of the bytecode interpreter. This is needed only for
the scan at beginning of a major GC cycle, not for the scan done
at every minor GC.
The instrumentation code in the instrumented runtime was replaced
with new APIs to gather runtime statistics and output them in a new format
(Common Trace Format).
This commit also exposes new functions in the Gc module to pause or resume
instrumentation during a program execution (Gc.eventlog_pause and
Gc.eventlog_resume).
The user can register several callbacks, which are called for various
events during the block's lifetime. We need to maintain a data
structure for tracked blocks in the runtime. When using threads,
callbacks can be called concurrently in a reentrant way, so the
functions manipulating this data structure need to be reentrant.
Stephen Dolan
Xavier Leroy
Enguerrand Decorne
Jacques-Henri Jourdan
KC Sivaramakrishnan
Sébastien Hinderer