implementation.
This patch aims to improve support for out-of-process JITing using OrcV2. It
introduces two new class templates, OrcRPCTargetProcessControlBase and
OrcRPCTPCServer, which together implement the TargetProcessControl API by
forwarding operations to an execution process via an Orc-RPC Endpoint. These
utilities are used to implement out-of-process JITing from llvm-jitlink to
a new llvm-jitlink-executor tool.
This patch also breaks the OrcJIT library into three parts:
-- OrcTargetProcess: Contains code needed by the JIT execution process.
-- OrcShared: Contains code needed by the JIT execution and compiler
processes
-- OrcJIT: Everything else.
This break-up allows JIT executor processes to link against OrcTargetProcess
and OrcShared only, without having to link in all of OrcJIT. Clients executing
JIT'd code in-process should start linking against OrcTargetProcess as well as
OrcJIT.
In the near future these changes will enable:
-- Removal of the OrcRemoteTargetClient/OrcRemoteTargetServer class templates
which provided similar functionality in OrcV1.
-- Restoration of Chapter 5 of the Building-A-JIT tutorial series, which will
serve as a simple usage example for these APIs.
-- Implementation of lazy, cross-target compilation in lli's -jit-kind=orc-lazy
mode.
TPCDynamicLibrarySearchGenerator was generating errors on missing
symbols, but that doesn't fit the DefinitionGenerator contract: A symbol
that isn't generated by a particular generator should not cause an
error.
This commit fixes the error by using SymbolLookupFlags::WeaklyReferencedSymbol
for all elements of the lookup, and switches llvm-jitlink to use
TPCDynamicLibrarySearchGenerator.
Subclasses will commonly gather that information from a remote during
construction, in which case they won't have meaningful values to pass to
TargetProcessControl's constructor.
TPCDynamicLibrarySearchGenerator uses a TargetProcessControl instance to
load libraries and search for symbol addresses in a target process. It
can be used in place of a DynamicLibrarySearchGenerator to enable
target-process agnostic lookup.
TargetProcessControl is a new API for communicating with JIT target processes.
It supports memory allocation and access, and inspection of some process
properties, e.g. the target proces triple and page size.
Centralizing these APIs allows utilities written against TargetProcessControl
to remain independent of the communication procotol with the target process
(which may be direct memory access/allocation for in-process JITing, or may
involve some form of IPC or RPC).
An initial set of TargetProcessControl-based utilities for lazy compilation is
provided by the TPCIndirectionUtils class.
An initial implementation of TargetProcessControl for in-process JITing
is provided by the SelfTargetProcessControl class.
An example program showing how the APIs can be used is provided in
llvm/examples/OrcV2Examples/LLJITWithTargetProcessControl.
Lang Hames