Fix translation of NVVM special registers to intrinsics.

The original implementation did not map the return value of the intrinsics
    call to the result value of the special register op. Uses of the result
    value hence hit a nullpointer.

--

PiperOrigin-RevId: 250255436

mlir/include/mlir/LLVMIR/NVVMOps.td

@@ -38,8 +38,8 @@ class NVVM_SpecialRegisterOp<string mnemonic,
     list<OpTrait> traits = []> :
   NVVM_Op<mnemonic, !listconcat(traits, [NoSideEffect])>,
   Results<(outs LLVM_Type:$res)>, Arguments<(ins)> {
-  string llvmBuilder = "createIntrinsicCall(builder, llvm::Intrinsic::nvvm_"
-    # !subst(".","_", mnemonic) # ");";
+  string llvmBuilder = "$res = createIntrinsicCall(builder,"
+    # "llvm::Intrinsic::nvvm_" # !subst(".","_", mnemonic) # ");";
   let parser = [{ return parseNVVMSpecialRegisterOp(parser, result); }];
   let printer = [{ printNVVMSpecialRegisterOp(p, this->getOperation()); }];
 }

mlir/include/mlir/Target/LLVMIR/ModuleTranslation.h

@@ -86,6 +86,7 @@ private:
   Module &mlirModule;
   std::unique_ptr<llvm::Module> llvmModule;
 
+protected:
   // Mappings between original and translated values, used for lookups.
   llvm::StringMap<llvm::Function *> functionMapping;
   llvm::DenseMap<Value *, llvm::Value *> valueMapping;

mlir/lib/Target/LLVMIR/ConvertToNVVMIR.cpp

@@ -34,11 +34,11 @@
 using namespace mlir;
 
 namespace {
-static void createIntrinsicCall(llvm::IRBuilder<> &builder,
-                                llvm::Intrinsic::ID intrinsic) {
+static llvm::Value *createIntrinsicCall(llvm::IRBuilder<> &builder,
+                                        llvm::Intrinsic::ID intrinsic) {
   llvm::Module *module = builder.GetInsertBlock()->getModule();
   llvm::Function *fn = llvm::Intrinsic::getDeclaration(module, intrinsic, {});
-  builder.CreateCall(fn);
+  return builder.CreateCall(fn);
 }
 
 class ModuleTranslation : public LLVM::ModuleTranslation {