The ShutdownRequested flag indicates to Services whether a shutdown
operation is already pending. Services may use this information to
optimize their book-keeping: either preparing for a (potentially
lengthy) detached state, or for an upcoming shutdown.
Session does not call onDetached yet: That (including setting the
ShutdownRequested argument) will happen in a follow-up patch.
SimpleNativeMemoryMap now captures a reference to the Session that it
was constructed for. This is used to fix some outstanding TODOs: using
the real page size for the process, and reporting errors that were
previously discarded.
Add named constructors to SimpleNativeMemoryMap to publish
SimpleNativeMemoryMap's controller interface when an instance is
constructed.
This supports correct setup by construction, since API clients can't
forget to publish the interface that the controller will need to
interact with the SimpleNativeMemoryMap object.
This provides clean separation between the ORC runtime code that
implements runtime functionality and the wrapper functions that permit
this code to be called from the controller via the
ExecutorProcessControl API.
Separating the controller interface from the implementation functions
should allow clients to introduce alternative serialization schemes if
they want (e.g. JSON).
In particular, this commit adds a new orc-rt/include/orc-rt/sps-ci
directory and moves SimpleNativeMemoryMap SPS controller interface into
a new header in that directory. This commit also splits the
implementation and testing of the SPS controller interface for
SimpleNativeMemoryMap into separate files.
The name "Service" better reflects the general purpose of this class: It
provides *something* (often resource management) to the Session, is
owned by the Session, and receives notifications from the Session when
the controller detaches / is detached, and when the Session is shut
down.
An example of a non-resource-managing Service (to be added in an
upcoming patch) is a detach / shutdown notification service: Clients can
add this service to register arbitrary callbacks to be run on detach /
shutdown. The advantage of this over the current Session detach /
shutdown callback system is that clients can control both the order of
the callbacks, and their order relative to notification of other
services.
This argument serves as an opaque id (outside the ControllerAccess
object) for a call to a wrapper function. I expect that most
ControllerAccess implementations will want to use this argument as a
sequence number (plain integer), for which uint64_t will be a better fit
than void*. For ControllerAccess implementations that want to use a
pointer, uint64_t should be sufficiently large.
7381558ef8b renamed the FinalizeRequest type to InitializeRequest. This commit
updates InitializeRequest variable names to follow suit ("FR"s become "IR"s).
This commit renames the "finalize" operation to "initialize", and
"deallocate" to "deinitialize".
The new names are chosen to better fit the point of view of the
ORC-runtime and executor-process: After memory is *reserved* it can be
*initialized* with some content, and *deinitialized* to return that
memory to the reserved region.
This seems more understandable to me than the original scheme, which
named these operations after the controller-side JITLinkMemoryManager
operations that they partially implemented. I.e.
SimpleNativeMemoryMap::finalize implemented the final step of
JITLinkMemoryManager::finalize, initializing the memory in the executor;
and SimpleNativeMemoryMap::deallocate implemented the final step of
JITLinkMemoryManager::deallocate, running dealloc actions and releasing
the finalized region.
The proper way to think of the relationship between these operations now
is that:
1. The final step of finalization is to initialize the memory in the
executor.
2. The final step of deallocation is to deinitialize the memory in the
executor.
In an ORC JIT it's common for multiple memory regions to be deallocated
at once, e.g. when a ResourceTracker covering multiple object files is
removed. This commit adds SimpleNativeMemoryMap::deallocateMultiple and
SimpleNativeMemoryMap::releaseMultiple APIs that can be used to reduce
the number of calls (and consequently IPC messages in cross-process
setups) in these cases.
Adding these operations will make it easier to write an
llvm::orc::MemoryMapper class that can use SimpleNativeMemoryMap as a
backend.
This commit aims to align SimpleNativeMemoryMap::FinalizeRequest::Segment with
llvm::orc::tpctypes::SegFinalizeRequest. This will simplify construction of a
new LLVM JITLinkMemoryManager that's capable of using SimpleNativeMemoryMap as
a backend.
SimpleNativeMemoryMap is a memory allocation backend for use with ORC.
It can...
1. Reserve slabs of address space.
2. Finalize regions of memory within a reserved slab: copying content
into requested addresses, applying memory protections, running
finalization actions, and storing deallocation actions to be run by
deallocate.
3. Deallocate finalized memory regions: running deallocate actions and,
if possible, making memory in these regions available for use by future
finalization operations. (Some systems prohibit reuse of executable
memory. On these systems deallocated memory is no longer usable within
the process).
4. Release reserved slabs. This runs deallocate for any
not-yet-deallocated finalized regions, and then (if possible) returns
the address space to system. (On systems that prohibit reuse of
executable memory parts of the released address space may be permanently
unusable by the process).
SimpleNativeMemoryMap is intended primarily for use by
llvm::orc::JITLinkMemoryManager implementations to allocate JIT'd code
and data.
