[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, 28 insertions, 12 deletions

diff --git a/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp b/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp
index b23ca88baf1..c35e5244ecd 100644
--- a/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp
+++ b/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp
@@ -21,7 +21,6 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/DebugInfo/DIContext.h"
-#include "llvm/ExecutionEngine/ObjectImage.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -32,6 +31,7 @@
 
 using namespace llvm;
 using namespace llvm::jitprofiling;
+using namespace llvm::object;
 
 #define DEBUG_TYPE "amplifier-jit-event-listener"
 
@@ -48,6 +48,7 @@ class IntelJITEventListener : public JITEventListener {
   typedef DenseMap<const void *, MethodAddressVector>  ObjectMap;
 
   ObjectMap  LoadedObjectMap;
+  std::map<const char*, OwningBinary<ObjectFile>> DebugObjects;
 
 public:
   IntelJITEventListener(IntelJITEventsWrapper* libraryWrapper) {
@@ -57,9 +58,10 @@ public:
   ~IntelJITEventListener() {
   }
 
-  virtual void NotifyObjectEmitted(const ObjectImage &Obj);
+  void NotifyObjectEmitted(const ObjectFile &Obj,
+                           const RuntimeDyld::LoadedObjectInfo &L) override;
 
-  virtual void NotifyFreeingObject(const ObjectImage &Obj);
+  void NotifyFreeingObject(const ObjectFile &Obj) override;
 };
 
 static LineNumberInfo DILineInfoToIntelJITFormat(uintptr_t StartAddress,
@@ -95,23 +97,29 @@ static iJIT_Method_Load FunctionDescToIntelJITFormat(
   return Result;
 }
 
-void IntelJITEventListener::NotifyObjectEmitted(const ObjectImage &Obj) {
+void IntelJITEventListener::NotifyObjectEmitted(
+                                       const ObjectFile &Obj,
+                                       const RuntimeDyld::LoadedObjectInfo &L) {
+
+  OwningBinary<ObjectFile> DebugObjOwner = L.getObjectForDebug(Obj);
+  const ObjectFile &DebugObj = *DebugObjOwner.getBinary();
+
   // Get the address of the object image for use as a unique identifier
-  const void* ObjData = Obj.getData().data();
-  DIContext* Context = DIContext::getDWARFContext(*Obj.getObjectFile());
+  const void* ObjData = DebugObj.getData().data();
+  DIContext* Context = DIContext::getDWARFContext(DebugObj);
   MethodAddressVector Functions;
 
   // Use symbol info to iterate functions in the object.
-  for (object::symbol_iterator I = Obj.begin_symbols(),
-                               E = Obj.end_symbols();
+  for (symbol_iterator I = DebugObj.symbol_begin(),
+                       E = DebugObj.symbol_end();
                         I != E;
                         ++I) {
     std::vector<LineNumberInfo> LineInfo;
     std::string SourceFileName;
 
-    object::SymbolRef::Type SymType;
+    SymbolRef::Type SymType;
     if (I->getType(SymType)) continue;
-    if (SymType == object::SymbolRef::ST_Function) {
+    if (SymType == SymbolRef::ST_Function) {
       StringRef  Name;
       uint64_t   Addr;
       uint64_t   Size;
@@ -162,11 +170,18 @@ void IntelJITEventListener::NotifyObjectEmitted(const ObjectImage &Obj) {
   // registered function addresses for each loaded object.  We will
   // use the MethodIDs map to get the registered ID for each function.
   LoadedObjectMap[ObjData] = Functions;
+  DebugObjects[Obj.getData().data()] = std::move(DebugObjOwner);
 }
 
-void IntelJITEventListener::NotifyFreeingObject(const ObjectImage &Obj) {
+void IntelJITEventListener::NotifyFreeingObject(const ObjectFile &Obj) {
+  // This object may not have been registered with the listener. If it wasn't,
+  // bail out.
+  if (DebugObjects.find(Obj.getData().data()) == DebugObjects.end())
+    return;
+
   // Get the address of the object image for use as a unique identifier
-  const void* ObjData = Obj.getData().data();
+  const ObjectFile &DebugObj = *DebugObjects[Obj.getData().data()].getBinary();
+  const void* ObjData = DebugObj.getData().data();
 
   // Get the object's function list from LoadedObjectMap
   ObjectMap::iterator OI = LoadedObjectMap.find(ObjData);
@@ -190,6 +205,7 @@ void IntelJITEventListener::NotifyFreeingObject(const ObjectImage &Obj) {
 
   // Erase the object from LoadedObjectMap
   LoadedObjectMap.erase(OI);
+  DebugObjects.erase(Obj.getData().data());
 }
 
 }  // anonymous namespace.