[MCJIT] Clean up RuntimeDyld's quirky object-ownership/modification scheme.

Previously, when loading an object file, RuntimeDyld (1) took ownership of the
ObjectFile instance (and associated MemoryBuffer), (2) potentially modified the
object in-place, and (3) returned an ObjectImage that managed ownership of the
now-modified object and provided some convenience methods. This scheme accreted
over several years as features were tacked on to RuntimeDyld, and was both
unintuitive and unsafe (See e.g. http://llvm.org/PR20722).

This patch fixes the issue by removing all ownership and in-place modification
of object files from RuntimeDyld. Existing behavior, including debugger
registration, is preserved.

Noteworthy changes include:

(1) ObjectFile instances are now passed to RuntimeDyld by const-ref.
(2) The ObjectImage and ObjectBuffer classes have been removed entirely, they
    existed to model ownership within RuntimeDyld, and so are no longer needed.
(3) RuntimeDyld::loadObject now returns an instance of a new class,
    RuntimeDyld::LoadedObjectInfo, which can be used to construct a modified
    object suitable for registration with the debugger, following the existing
    debugger registration scheme.
(4) The JITRegistrar class has been removed, and the GDBRegistrar class has been
    re-written as a JITEventListener.

This should fix http://llvm.org/PR20722 .

llvm-svn: 222810

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/tools/lli/RemoteMemoryManager.h b/llvm/tools/lli/RemoteMemoryManager.h
index 0bdb4e2ad12..895bcdac4d1 100644
--- a/llvm/tools/lli/RemoteMemoryManager.h
+++ b/llvm/tools/lli/RemoteMemoryManager.h
@@ -80,7 +80,8 @@ public:
   // symbols from Modules it contains.
   uint64_t getSymbolAddress(const std::string &Name) override { return 0; }
 
-  void notifyObjectLoaded(ExecutionEngine *EE, const ObjectImage *Obj) override;
+  void notifyObjectLoaded(ExecutionEngine *EE,
+                          const object::ObjectFile &Obj) override;
 
   bool finalizeMemory(std::string *ErrMsg) override;