Finish cross-process JIT work, and clean up previous work.

1. When the JIT is asked to remove a function, updating it's
   mapping to 0, we invalidate any function stubs used only 
   by that function.  Now, also invalidate the JIT's mapping
   from the GV the stub pointed to, to the address of the GV.

2. When dlsym stubs for cross-process JIT are enabled, do not
   abort just because a named function cannot be found in the
   JIT's process.

3. Fix various assumptions about when it is ok to use the lazy
   resolver when non-lazy JITing is enabled.

llvm-svn: 66324

llvm/lib/ExecutionEngine/JIT/JIT.cpp

@@ -580,7 +580,8 @@ void *JIT::getPointerToFunction(Function *F) {
   }
 
   if (F->isDeclaration()) {
-    bool AbortOnFailure = F->getLinkage() != GlobalValue::ExternalWeakLinkage;
+    bool AbortOnFailure = !areDlsymStubsEnabled() &&
+                          F->getLinkage() != GlobalValue::ExternalWeakLinkage;
     void *Addr = getPointerToNamedFunction(F->getName(), AbortOnFailure);
     addGlobalMapping(F, Addr);
     return Addr;

llvm/lib/ExecutionEngine/JIT/JITEmitter.cpp

@@ -123,7 +123,7 @@ namespace {
     /// getFunctionStub - This returns a pointer to a function stub, creating
     /// one on demand as needed.  If empty is true, create a function stub
     /// pointing at address 0, to be filled in later.
-    void *getFunctionStub(Function *F, bool empty = false);
+    void *getFunctionStub(Function *F);
 
     /// getExternalFunctionStub - Return a stub for the function at the
     /// specified address, created lazily on demand.
@@ -174,26 +174,32 @@ void *JITResolver::getFunctionStubIfAvailable(Function *F) {
 
 /// getFunctionStub - This returns a pointer to a function stub, creating
 /// one on demand as needed.
-void *JITResolver::getFunctionStub(Function *F, bool empty) {
+void *JITResolver::getFunctionStub(Function *F) {
   MutexGuard locked(TheJIT->lock);
 
   // If we already have a stub for this function, recycle it.
   void *&Stub = state.getFunctionToStubMap(locked)[F];
   if (Stub) return Stub;
 
-  // Call the lazy resolver function unless we already KNOW it is an external
-  // function, in which case we just skip the lazy resolution step.
-  void *Actual = empty ? (void*)0 : (void*)(intptr_t)LazyResolverFn;
+  // Call the lazy resolver function unless we are JIT'ing non-lazily, in which
+  // case we must resolve the symbol now.
+  void *Actual =  TheJIT->isLazyCompilationDisabled() 
+    ? (void *)0 : (void *)(intptr_t)LazyResolverFn;
+   
+  // If this is an external declaration, attempt to resolve the address now
+  // to place in the stub.
   if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode()) {
     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 (!Actual) return 0;
+    // 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;
   }
 
-  // Otherwise, codegen a new stub.  For now, the stub will call the lazy
-  // resolver function.
+  // Codegen a new stub, calling the lazy resolver or the actual address of the
+  // external function, if it was resolved.
   Stub = TheJIT->getJITInfo().emitFunctionStub(F, Actual,
                                                *TheJIT->getCodeEmitter());
 
@@ -211,10 +217,12 @@ void *JITResolver::getFunctionStub(Function *F, bool empty) {
   // JITCompilerFn knows which function to compile!
   state.getStubToFunctionMap(locked)[Stub] = F;
   
-  // If this is an "empty" stub, then inform the JIT that it will need to
-  // JIT the function so an address can be provided.
-  if (empty)
-    TheJIT->addPendingFunction(F);
+  // If we are JIT'ing non-lazily but need to call a function that does not
+  // exist yet, add it to the JIT's work list so that we can fill in the stub
+  // address later.
+  if (!Actual && TheJIT->isLazyCompilationDisabled())
+    if (!F->isDeclaration() || F->hasNotBeenReadFromBitcode())
+      TheJIT->addPendingFunction(F);
   
   return Stub;
 }
@@ -706,30 +714,29 @@ 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.
-  if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode() && DoesntNeedStub)
+  // 'compile' it, which really just adds it to the map.  In dlsym mode, 
+  // external functions are forced through a stub, regardless of reloc type.
+  if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode() &&
+      DoesntNeedStub && !TheJIT->areDlsymStubsEnabled())
     return TheJIT->getPointerToFunction(F);
 
-  // If we are jitting non-lazily but encounter a function that has not been
-  // jitted yet, we need to allocate a blank stub to call the function
-  // once we JIT it and its address is known.
-  if (TheJIT->isLazyCompilationDisabled())
-    if (!F->isDeclaration() || F->hasNotBeenReadFromBitcode())
-      return Resolver.getFunctionStub(F, true);
-  
   // Okay, the function has not been compiled yet, if the target callback
   // mechanism is capable of rewriting the instruction directly, prefer to do
-  // that instead of emitting a stub.
-  if (DoesntNeedStub)
+  // that instead of emitting a stub.  This uses the lazy resolver, so is not
+  // legal if lazy compilation is disabled.
+  if (DoesntNeedStub && !TheJIT->isLazyCompilationDisabled())
     return Resolver.AddCallbackAtLocation(F, Reference);
 
-  // Otherwise, we have to emit a lazy resolving stub.
+  // Otherwise, we have to emit a stub.
   void *StubAddr = Resolver.getFunctionStub(F);
 
   // Add the stub to the current function's list of referenced stubs, so we can
-  // deallocate them if the current function is ever freed.
-  AddStubToCurrentFunction(StubAddr);
-  
+  // deallocate them if the current function is ever freed.  It's possible to
+  // return null from getFunctionStub in the case of a weak extern that fails
+  // to resolve.
+  if (StubAddr)
+    AddStubToCurrentFunction(StubAddr);
+
   return StubAddr;
 }
 
@@ -1189,7 +1196,9 @@ void JITEmitter::deallocateMemForFunction(Function *F) {
     // in the JITResolver.  Were there a memory manager deallocateStub routine,
     // we could call that at this point too.
     if (FnRefs.empty()) {
-      Resolver.invalidateStub(Stub);
+      DOUT << "\nJIT: Invalidated Stub at [" << Stub << "]\n";
+      GlobalValue *GV = Resolver.invalidateStub(Stub);
+      TheJIT->updateGlobalMapping(GV, 0);
       StubFnRefs.erase(F);
     }
   }