Adding support for deregistering EH frames with MCJIT.

Patch by Yaron Keren



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192753 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ExecutionEngine/RTDyldMemoryManager.h

@@ -60,6 +60,8 @@ public:
   /// be the case for local execution) these two values will be the same.
   virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, size_t Size);
 
+  virtual void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr, size_t Size);
+
   /// This method returns the address of the specified function or variable.
   /// It is used to resolve symbols during module linking.
   virtual uint64_t getSymbolAddress(const std::string &Name);

include/llvm/ExecutionEngine/RuntimeDyld.h

@@ -71,6 +71,8 @@ public:
   /// the actual target-specific EH frame registration.
   void registerEHFrames();
 
+  void deregisterEHFrames();
+
   StringRef getErrorString();
 };
 

lib/ExecutionEngine/MCJIT/MCJIT.cpp

@@ -62,6 +62,8 @@ MCJIT::MCJIT(Module *m, TargetMachine *tm, RTDyldMemoryManager *MM,
 }
 
 MCJIT::~MCJIT() {
+  Dyld.deregisterEHFrames();
+
   LoadedObjectMap::iterator it, end = LoadedObjects.end();
   for (it = LoadedObjects.begin(); it != end; ++it) {
     ObjectImage *Obj = it->second;

lib/ExecutionEngine/MCJIT/MCJIT.h

@@ -55,6 +55,12 @@ public:
     ClientMM->registerEHFrames(Addr, LoadAddr, Size);
   }
 
+  virtual void deregisterEHFrames(uint8_t *Addr,
+                                  uint64_t LoadAddr,
+                                  size_t Size) {
+    ClientMM->deregisterEHFrames(Addr, LoadAddr, Size);
+  }
+
   virtual bool finalizeMemory(std::string *ErrMsg = 0) {
     return ClientMM->finalizeMemory(ErrMsg);
   }

lib/ExecutionEngine/RTDyldMemoryManager.cpp

@@ -42,17 +42,53 @@ RTDyldMemoryManager::~RTDyldMemoryManager() {}
 
 #if HAVE_EHTABLE_SUPPORT
 extern "C" void __register_frame(void*);
+extern "C" void __deregister_frame(void*);
+#else
+// The building compiler does not have __(de)register_frame but
+// it may be found at runtime in a dynamically-loaded library.
+// For example, this happens when building LLVM with Visual C++
+// but using the MingW runtime.
+void __register_frame(void *p) {
+  static bool Searched = false;
+  static void *rf = 0;
 
-static const char *processFDE(const char *Entry) {
+  if (!Searched) {
+    Searched = true;
+    rf = llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
+                                                      "__register_frame");
+  }
+  if (rf)
+    ((void (*)(void *))rf)(p);
+}
+
+void __deregister_frame(void *p) {
+  static bool Searched = false;
+  static void *df = 0;
+
+  if (!Searched) {
+    Searched = true;
+    df = llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
+                                                      "__deregister_frame");
+  }
+  if (df)
+    ((void (*)(void *))df)(p);
+}
+#endif
+
+#ifdef __APPLE__
+
+static const char *processFDE(const char *Entry, bool isDeregister) {
   const char *P = Entry;
   uint32_t Length = *((const uint32_t *)P);
   P += 4;
   uint32_t Offset = *((const uint32_t *)P);
   if (Offset != 0)
-    __register_frame(const_cast<char *>(Entry));
+    if (isDeregister)
+      __deregister_frame(const_cast<char *>(Entry));
+    else
+      __register_frame(const_cast<char *>(Entry));
   return P + Length;
 }
-#endif
 
 // This implementation handles frame registration for local targets.
 // Memory managers for remote targets should re-implement this function
@@ -60,15 +96,50 @@ static const char *processFDE(const char *Entry) {
 void RTDyldMemoryManager::registerEHFrames(uint8_t *Addr,
                                            uint64_t LoadAddr,
                                            size_t Size) {
-#if HAVE_EHTABLE_SUPPORT
+  // On OS X OS X __register_frame takes a single FDE as an argument.
+  // See http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-April/061768.html
   const char *P = (const char *)Addr;
   const char *End = P + Size;
   do  {
-    P = processFDE(P);
+    P = processFDE(P, false);
   } while(P != End);
-#endif
 }
 
+void RTDyldMemoryManager::deregisterEHFrames(uint8_t *Addr,
+                                           uint64_t LoadAddr,
+                                           size_t Size) {
+  const char *P = (const char *)Addr;
+  const char *End = P + Size;
+  do  {
+    P = processFDE(P, true);
+  } while(P != End);
+}
+
+#else
+
+void RTDyldMemoryManager::registerEHFrames(uint8_t *Addr,
+                                           uint64_t LoadAddr,
+                                           size_t Size) {
+  // On Linux __register_frame takes a single argument: 
+  // a pointer to the start of the .eh_frame section.
+
+  // How can it find the end? Because crtendS.o is linked 
+  // in and it has an .eh_frame section with four zero chars.
+  // FIXME: make sure EH frame is followed by four zero bytes.
+  // This should be done in the linker RuntimeDyldELF::getEHFrameSection(),
+  // return pointer to .eh_frame properly appended by four zero bytes.
+  // If the linker can not fixed, do it here.
+  __register_frame(Addr);
+}
+
+void RTDyldMemoryManager::deregisterEHFrames(uint8_t *Addr,
+                                           uint64_t LoadAddr,
+                                           size_t Size) {
+  __deregister_frame(Addr);
+}
+
+#endif
+
 static int jit_noop() {
   return 0;
 }

lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

@@ -32,6 +32,9 @@ namespace llvm {
 void RuntimeDyldImpl::registerEHFrames() {
 }
 
+void RuntimeDyldImpl::deregisterEHFrames() {
+}
+
 // Resolve the relocations for all symbols we currently know about.
 void RuntimeDyldImpl::resolveRelocations() {
   // First, resolve relocations associated with external symbols.
@@ -595,7 +598,13 @@ StringRef RuntimeDyld::getErrorString() {
 }
 
 void RuntimeDyld::registerEHFrames() {
-  return Dyld->registerEHFrames();
+  if (Dyld)
+    Dyld->registerEHFrames();
+}
+
+void RuntimeDyld::deregisterEHFrames() {
+  if (Dyld)
+    Dyld->deregisterEHFrames();
 }
 
 } // end namespace llvm

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

@@ -160,10 +160,24 @@ void RuntimeDyldELF::registerEHFrames() {
     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
     size_t EHFrameSize = Sections[EHFrameSID].Size;
     MemMgr->registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
+    RegisteredEHFrameSections.push_back(EHFrameSID);
   }
   UnregisteredEHFrameSections.clear();
 }
 
+void RuntimeDyldELF::deregisterEHFrames() {
+  if (!MemMgr)
+    return;
+  for (int i = 0, e = RegisteredEHFrameSections.size(); i != e; ++i) {
+    SID EHFrameSID = RegisteredEHFrameSections[i];
+    uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
+    uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
+    size_t EHFrameSize = Sections[EHFrameSID].Size;
+    MemMgr->deregisterEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
+  }
+  RegisteredEHFrameSections.clear();
+}
+
 ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
   if (Buffer->getBufferSize() < ELF::EI_NIDENT)
     llvm_unreachable("Unexpected ELF object size");

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.h

@@ -126,6 +126,7 @@ class RuntimeDyldELF : public RuntimeDyldImpl {
   // in a table until we receive a request to register all unregistered
   // EH frame sections with the memory manager.
   SmallVector<SID, 2> UnregisteredEHFrameSections;
+  SmallVector<SID, 2> RegisteredEHFrameSections;
 
 public:
   RuntimeDyldELF(RTDyldMemoryManager *mm) : RuntimeDyldImpl(mm)
@@ -141,6 +142,7 @@ public:
   virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const;
   virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
   virtual void registerEHFrames();
+  virtual void deregisterEHFrames();
   virtual void finalizeLoad(ObjSectionToIDMap &SectionMap);
   virtual ~RuntimeDyldELF();
 };

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h

@@ -342,6 +342,8 @@ public:
 
   virtual void registerEHFrames();
 
+  virtual void deregisterEHFrames();
+
   virtual void finalizeLoad(ObjSectionToIDMap &SectionMap) {}
 };
 

tools/lli/RemoteMemoryManager.h

@@ -87,6 +87,7 @@ public:
   // For now, remote EH frame registration isn't supported.  Remote symbol
   // resolution is a prerequisite to supporting remote EH frame registration.
   void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, size_t Size) {}
+  void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr, size_t Size) {}
 
   // This is a non-interface function used by lli
   void setRemoteTarget(RemoteTarget *T) { Target = T; }