Remove dlsym stubs, with Nate Begeman's permission.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86606 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ExecutionEngine/ExecutionEngine.h

@@ -91,7 +91,6 @@ class ExecutionEngine {
   bool CompilingLazily;
   bool GVCompilationDisabled;
   bool SymbolSearchingDisabled;
-  bool DlsymStubsEnabled;
 
   friend class EngineBuilder;  // To allow access to JITCtor and InterpCtor.
 
@@ -369,15 +368,7 @@ public:
   bool isSymbolSearchingDisabled() const {
     return SymbolSearchingDisabled;
   }
-  
-  /// EnableDlsymStubs - 
-  void EnableDlsymStubs(bool Enabled = true) {
-    DlsymStubsEnabled = Enabled;
-  }
-  bool areDlsymStubsEnabled() const {
-    return DlsymStubsEnabled;
-  }
-  
+
   /// InstallLazyFunctionCreator - If an unknown function is needed, the
   /// specified function pointer is invoked to create it.  If it returns null,
   /// the JIT will abort.

include/llvm/ExecutionEngine/JITMemoryManager.h

@@ -71,17 +71,6 @@ public:
   /// return a pointer to its base.
   virtual uint8_t *getGOTBase() const = 0;
   
-  /// SetDlsymTable - If the JIT must be able to relocate stubs after they have
-  /// been emitted, potentially because they are being copied to a process
-  /// where external symbols live at different addresses than in the JITing
-  ///  process, allocate a table with sufficient information to do so.
-  virtual void SetDlsymTable(void *ptr) = 0;
-  
-  /// getDlsymTable - If this is managing a table of entries so that stubs to
-  /// external symbols can be later relocated, this method should return a
-  /// pointer to it.
-  virtual void *getDlsymTable() const = 0;
-  
   /// NeedsExactSize - If the memory manager requires to know the size of the
   /// objects to be emitted
   bool NeedsExactSize() const {

lib/ExecutionEngine/ExecutionEngine.cpp

@@ -52,7 +52,6 @@ ExecutionEngine::ExecutionEngine(ModuleProvider *P)
   CompilingLazily         = false;
   GVCompilationDisabled   = false;
   SymbolSearchingDisabled = false;
-  DlsymStubsEnabled       = false;
   Modules.push_back(P);
   assert(P && "ModuleProvider is null?");
 }

lib/ExecutionEngine/JIT/JIT.cpp

@@ -613,11 +613,6 @@ void JIT::runJITOnFunctionUnlocked(Function *F, const MutexGuard &locked) {
     // the stub with real address of the function.
     updateFunctionStub(PF);
   }
-  
-  // If the JIT is configured to emit info so that dlsym can be used to
-  // rewrite stubs to external globals, do so now.
-  if (areDlsymStubsEnabled() && !isCompilingLazily())
-    updateDlsymStubTable();
 }
 
 /// getPointerToFunction - This method is used to get the address of the
@@ -660,8 +655,7 @@ void *JIT::getPointerToFunction(Function *F) {
   }
 
   if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
-    bool AbortOnFailure =
-      !areDlsymStubsEnabled() && !F->hasExternalWeakLinkage();
+    bool AbortOnFailure = !F->hasExternalWeakLinkage();
     void *Addr = getPointerToNamedFunction(F->getName(), AbortOnFailure);
     addGlobalMapping(F, Addr);
     return Addr;
@@ -690,7 +684,7 @@ void *JIT::getOrEmitGlobalVariable(const GlobalVariable *GV) {
       return (void*)&__dso_handle;
 #endif
     Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(GV->getName());
-    if (Ptr == 0 && !areDlsymStubsEnabled()) {
+    if (Ptr == 0) {
       llvm_report_error("Could not resolve external global address: "
                         +GV->getName());
     }

lib/ExecutionEngine/JIT/JIT.h

@@ -195,7 +195,6 @@ private:
                                        TargetMachine &tm);
   void runJITOnFunctionUnlocked(Function *F, const MutexGuard &locked);
   void updateFunctionStub(Function *F);
-  void updateDlsymStubTable();
 
 protected:
 

lib/ExecutionEngine/JIT/JITEmitter.cpp

@@ -369,10 +369,6 @@ namespace {
     // the stub is unused.
     DenseMap<void *, SmallPtrSet<const Function*, 1> > StubFnRefs;
     
-    // ExtFnStubs - A map of external function names to stubs which have entries
-    // in the JITResolver's ExternalFnToStubMap.
-    StringMap<void *> ExtFnStubs;
-
     DebugLocTuple PrevDLT;
 
   public:
@@ -461,10 +457,6 @@ namespace {
     /// deallocateMemForFunction to also remove stubs no longer referenced.
     void AddStubToCurrentFunction(void *Stub);
     
-    /// getExternalFnStubs - Accessor for the JIT to find stubs emitted for
-    /// MachineRelocations that reference external functions by name.
-    const StringMap<void*> &getExternalFnStubs() const { return ExtFnStubs; }
-    
     virtual void processDebugLoc(DebugLoc DL, bool BeforePrintingInsn);
 
     virtual void emitLabel(uint64_t LabelID) {
@@ -536,10 +528,8 @@ void *JITResolver::getFunctionStub(Function *F) {
     Actual = TheJIT->getPointerToFunction(F);
 
     // If we resolved the symbol to a null address (eg. a weak external)
-    // don't emit a stub. Return a null pointer to the application.  If dlsym
-    // stubs are enabled, not being able to resolve the address is not
-    // meaningful.
-    if (!Actual && !TheJIT->areDlsymStubsEnabled()) return 0;
+    // don't emit a stub. Return a null pointer to the application.
+    if (!Actual) return 0;
   }
 
   // Codegen a new stub, calling the lazy resolver or the actual address of the
@@ -758,10 +748,9 @@ void *JITEmitter::getPointerToGlobal(GlobalValue *V, void *Reference,
   if (ResultPtr) return ResultPtr;
 
   // If this is an external function pointer, we can force the JIT to
-  // 'compile' it, which really just adds it to the map.  In dlsym mode, 
-  // external functions are forced through a stub, regardless of reloc type.
+  // 'compile' it, which really just adds it to the map.
   if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode() &&
-      !MayNeedFarStub && !TheJIT->areDlsymStubsEnabled())
+      !MayNeedFarStub)
     return TheJIT->getPointerToFunction(F);
 
   // Okay, the function has not been compiled yet, if the target callback
@@ -1112,16 +1101,7 @@ bool JITEmitter::finishFunction(MachineFunction &F) {
 
           // If the target REALLY wants a stub for this function, emit it now.
           if (MR.mayNeedFarStub()) {
-            if (!TheJIT->areDlsymStubsEnabled()) {
-              ResultPtr = Resolver.getExternalFunctionStub(ResultPtr);
-            } else {
-              void *&Stub = ExtFnStubs[MR.getExternalSymbol()];
-              if (!Stub) {
-                Stub = Resolver.getExternalFunctionStub((void *)&Stub);
-                AddStubToCurrentFunction(Stub);
-              }
-              ResultPtr = Stub;
-            }
+            ResultPtr = Resolver.getExternalFunctionStub(ResultPtr);
           }
         } else if (MR.isGlobalValue()) {
           ResultPtr = getPointerToGlobal(MR.getGlobalValue(),
@@ -1335,19 +1315,10 @@ void JITEmitter::deallocateMemForFunction(const Function *F) {
       StubFnRefs.erase(Stub);
 
       // Invalidate the stub.  If it is a GV stub, update the JIT's global
-      // mapping for that GV to zero, otherwise, search the string map of
-      // external function names to stubs and remove the entry for this stub.
+      // mapping for that GV to zero.
       GlobalValue *GV = Resolver.invalidateStub(Stub);
       if (GV) {
         TheJIT->updateGlobalMapping(GV, 0);
-      } else {
-        for (StringMapIterator<void*> i = ExtFnStubs.begin(),
-             e = ExtFnStubs.end(); i != e; ++i) {
-          if (i->second == Stub) {
-            ExtFnStubs.erase(i);
-            break;
-          }
-        }
       }
     }
   }
@@ -1588,92 +1559,6 @@ void JIT::updateFunctionStub(Function *F) {
   getJITInfo().emitFunctionStubAtAddr(F, Addr, Stub, *getCodeEmitter());
 }
 
-/// updateDlsymStubTable - Emit the data necessary to relocate the stubs
-/// that were emitted during code generation.
-///
-void JIT::updateDlsymStubTable() {
-  assert(isa<JITEmitter>(JCE) && "Unexpected MCE?");
-  JITEmitter *JE = cast<JITEmitter>(getCodeEmitter());
-  
-  SmallVector<GlobalValue*, 8> GVs;
-  SmallVector<void*, 8> Ptrs;
-  const StringMap<void *> &ExtFns = JE->getExternalFnStubs();
-
-  JE->getJITResolver().getRelocatableGVs(GVs, Ptrs);
-
-  unsigned nStubs = GVs.size() + ExtFns.size();
-  
-  // If there are no relocatable stubs, return.
-  if (nStubs == 0)
-    return;
-
-  // If there are no new relocatable stubs, return.
-  void *CurTable = JE->getMemMgr()->getDlsymTable();
-  if (CurTable && (*(unsigned *)CurTable == nStubs))
-    return;
-  
-  // Calculate the size of the stub info
-  unsigned offset = 4 + 4 * nStubs + sizeof(intptr_t) * nStubs;
-  
-  SmallVector<unsigned, 8> Offsets;
-  for (unsigned i = 0; i != GVs.size(); ++i) {
-    Offsets.push_back(offset);
-    offset += GVs[i]->getName().size() + 1;
-  }
-  for (StringMapConstIterator<void*> i = ExtFns.begin(), e = ExtFns.end(); 
-       i != e; ++i) {
-    Offsets.push_back(offset);
-    offset += strlen(i->first()) + 1;
-  }
-  
-  // Allocate space for the new "stub", which contains the dlsym table.
-  JE->startGVStub(0, offset, 4);
-  
-  // Emit the number of records
-  JE->emitInt32(nStubs);
-  
-  // Emit the string offsets
-  for (unsigned i = 0; i != nStubs; ++i)
-    JE->emitInt32(Offsets[i]);
-  
-  // Emit the pointers.  Verify that they are at least 2-byte aligned, and set
-  // the low bit to 0 == GV, 1 == Function, so that the client code doing the
-  // relocation can write the relocated pointer at the appropriate place in
-  // the stub.
-  for (unsigned i = 0; i != GVs.size(); ++i) {
-    intptr_t Ptr = (intptr_t)Ptrs[i];
-    assert((Ptr & 1) == 0 && "Stub pointers must be at least 2-byte aligned!");
-    
-    if (isa<Function>(GVs[i]))
-      Ptr |= (intptr_t)1;
-           
-    if (sizeof(Ptr) == 8)
-      JE->emitInt64(Ptr);
-    else
-      JE->emitInt32(Ptr);
-  }
-  for (StringMapConstIterator<void*> i = ExtFns.begin(), e = ExtFns.end(); 
-       i != e; ++i) {
-    intptr_t Ptr = (intptr_t)i->second | 1;
-
-    if (sizeof(Ptr) == 8)
-      JE->emitInt64(Ptr);
-    else
-      JE->emitInt32(Ptr);
-  }
-  
-  // Emit the strings.
-  for (unsigned i = 0; i != GVs.size(); ++i)
-    JE->emitString(GVs[i]->getName());
-  for (StringMapConstIterator<void*> i = ExtFns.begin(), e = ExtFns.end(); 
-       i != e; ++i)
-    JE->emitString(i->first());
-  
-  // Tell the JIT memory manager where it is.  The JIT Memory Manager will
-  // deallocate space for the old one, if one existed.
-  JE->getMemMgr()->SetDlsymTable(JE->finishGVStub(0));
-}
-
 /// freeMachineCodeForFunction - release machine code memory for given Function.
 ///
 void JIT::freeMachineCodeForFunction(Function *F) {

lib/ExecutionEngine/JIT/JITMemoryManager.cpp

@@ -296,7 +296,6 @@ namespace {
     MemoryRangeHeader *CurBlock;
 
     uint8_t *GOTBase;     // Target Specific reserved memory
-    void *DlsymTable;     // Stub external symbol information
   public:
     DefaultJITMemoryManager();
     ~DefaultJITMemoryManager();
@@ -318,7 +317,6 @@ namespace {
     static const size_t DefaultSizeThreshold;
 
     void AllocateGOT();
-    void SetDlsymTable(void *);
 
     // Testing methods.
     virtual bool CheckInvariants(std::string &ErrorStr);
@@ -469,10 +467,6 @@ namespace {
       return GOTBase;
     }
     
-    void *getDlsymTable() const {
-      return DlsymTable;
-    }
-    
     void deallocateBlock(void *Block) {
       // Find the block that is allocated for this function.
       MemoryRangeHeader *MemRange = static_cast<MemoryRangeHeader*>(Block) - 1;
@@ -599,7 +593,6 @@ DefaultJITMemoryManager::DefaultJITMemoryManager()
   FreeMemoryList = Mem0;
 
   GOTBase = NULL;
-  DlsymTable = NULL;
 }
 
 void DefaultJITMemoryManager::AllocateGOT() {
@@ -608,10 +601,6 @@ void DefaultJITMemoryManager::AllocateGOT() {
   HasGOT = true;
 }
 
-void DefaultJITMemoryManager::SetDlsymTable(void *ptr) {
-  DlsymTable = ptr;
-}
-
 DefaultJITMemoryManager::~DefaultJITMemoryManager() {
   for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
     sys::Memory::ReleaseRWX(CodeSlabs[i]);

unittests/ExecutionEngine/JIT/JITTest.cpp

@@ -68,8 +68,6 @@ public:
   virtual void setPoisonMemory(bool poison) { Base->setPoisonMemory(poison); }
   virtual void AllocateGOT() { Base->AllocateGOT(); }
   virtual uint8_t *getGOTBase() const { return Base->getGOTBase(); }
-  virtual void SetDlsymTable(void *ptr) { Base->SetDlsymTable(ptr); }
-  virtual void *getDlsymTable() const { return Base->getDlsymTable(); }
   struct StartFunctionBodyCall {
     StartFunctionBodyCall(uint8_t *Result, const Function *F,
                           uintptr_t ActualSize, uintptr_t ActualSizeResult)
@@ -303,7 +301,6 @@ TEST_F(JITTest, FarCallToKnownFunction) {
       ConstantInt::get(TypeBuilder<int, false>::get(Context), 7));
   Builder.CreateRet(result);
 
-  TheJIT->EnableDlsymStubs(false);
   TheJIT->DisableLazyCompilation(true);
   int (*TestFunctionPtr)() = reinterpret_cast<int(*)()>(
       (intptr_t)TheJIT->getPointerToFunction(TestFunction));