Fixed bug: For internal df nodes with void return types, the genvisc pass was

not producing empty struct as return type. Fixed it

llvm/lib/Transforms/GenVISC/GenVISC.cpp

@@ -33,6 +33,7 @@ namespace genvisc {
 // Helper Functions
 
 static inline ConstantInt* getTimerID(Module&, enum visc_TimerID);
+static void transformReturnTypeToStruct(Function* F);
 
 // Check if the dummy function call is a __visc__node call
 #define IS_VISC_CALL(callName) \
@@ -870,6 +871,7 @@ bool GenVISC::runOnModule(Module &M) {
         DEBUG(errs() << *LaunchF << "\n");
         // Get i8* cast to function pointer
         Function* graphFunc = cast<Function>(CI->getArgOperand(1));
+        transformReturnTypeToStruct(graphFunc);
         Constant* F = ConstantExpr::getPointerCast(graphFunc, Type::getInt8PtrTy(Ctx));
 
         ConstantInt* Op = cast<ConstantInt>(CI->getArgOperand(0));
@@ -916,6 +918,7 @@ bool GenVISC::runOnModule(Module &M) {
 
         // Get i8* cast to function pointer
         Function* graphFunc = cast<Function>(CI->getArgOperand(0));
+        transformReturnTypeToStruct(graphFunc);
         Constant* F = ConstantExpr::getPointerCast(graphFunc, Type::getInt8PtrTy(Ctx));
 
         CallInst* CreateNodeInst = CallInst::Create(CreateNodeF,
@@ -933,6 +936,7 @@ bool GenVISC::runOnModule(Module &M) {
 
         // Get i8* cast to function pointer
         Function* graphFunc = cast<Function>(CI->getArgOperand(0));
+        transformReturnTypeToStruct(graphFunc);
         Constant* F = ConstantExpr::getPointerCast(graphFunc, Type::getInt8PtrTy(Ctx));
 
         Value* CreateNode1DArgs[] = {F, CI->getArgOperand(1)};
@@ -950,6 +954,7 @@ bool GenVISC::runOnModule(Module &M) {
 
         // Get i8* cast to function pointer
         Function* graphFunc = cast<Function>(CI->getArgOperand(0));
+        transformReturnTypeToStruct(graphFunc);
         Constant* F = ConstantExpr::getPointerCast(graphFunc, Type::getInt8PtrTy(Ctx));
 
         Value* CreateNode2DArgs[] = {F, CI->getArgOperand(1), CI->getArgOperand(2)};
@@ -967,6 +972,7 @@ bool GenVISC::runOnModule(Module &M) {
 
         // Get i8* cast to function pointer
         Function* graphFunc = cast<Function>(CI->getArgOperand(0));
+        transformReturnTypeToStruct(graphFunc);
         Constant* F = ConstantExpr::getPointerCast(graphFunc, Type::getInt8PtrTy(Ctx));
 
         Value* CreateNode3DArgs[] = {F, CI->getArgOperand(1),
@@ -1476,6 +1482,33 @@ static inline ConstantInt* getTimerID(Module& M, enum visc_TimerID timer) {
   return ConstantInt::get(Type::getInt32Ty(M.getContext()), timer);
 }
 
+static void transformReturnTypeToStruct(Function* F) {
+  // Currently only works for void return types
+  errs() << "Transforming return type of function to Struct: " << F->getName() << "\n";
+  if(!F->getReturnType()->isVoidTy()) {
+    errs() << "Warning: Unhandled case - Only void return type handled\n";
+    return;
+  }
+  // Create the argument type list with added argument types
+  std::vector<Type*> ArgTypes;
+  for(Function::const_arg_iterator ai = F->arg_begin(), ae = F->arg_end();
+      ai != ae; ++ai) {
+    ArgTypes.push_back(ai->getType());
+  }
+  
+  StructType* RetTy = StructType::create(F->getContext(), None, "emptyStruct", true);
+  FunctionType* FTy = FunctionType::get(RetTy, ArgTypes, F->isVarArg());
+  PointerType* PTy = FTy->getPointerTo();
+  F->mutateType(PTy);
+  // Replace ret void instruction with ret %RetTy undef
+  for(auto& BB: F->getBasicBlockList()) {
+    if(ReturnInst* RI = dyn_cast<ReturnInst>(BB.getTerminator())) {
+      DEBUG(errs() << "Found return inst: "<< *RI << "\n");
+      ReturnInst* newRI = ReturnInst::Create(F->getContext(), UndefValue::get(RetTy));
+      ReplaceInstWithInst(RI, newRI);
+    }
+  }
+}
 
 char GenVISC::ID = 0;
 static RegisterPass<GenVISC> X("genvisc", "Pass to generate VISC IR from LLVM IR (with dummy function calls)", false, false);