RISCV: [Codegen] Add GenerateNop

Test: m test-art-host-gtest
Bug: 283082089
Signed-off-by: Lifang Xia <lifang_xia@linux.alibaba.com>
Signed-off-by: Wendong Wang <wangwd@xcvmbyte.com>
Change-Id: Iaa62836e1b322243abcaa314efb570f65272a834
diff --git a/compiler/optimizing/code_generator_riscv64.cc b/compiler/optimizing/code_generator_riscv64.cc
index a58378b..02a50a1 100644
--- a/compiler/optimizing/code_generator_riscv64.cc
+++ b/compiler/optimizing/code_generator_riscv64.cc
@@ -2889,7 +2889,9 @@
   GetAssembler()->cfi().AdjustCFAOffset(-adjustment32);
 }
 
-void CodeGeneratorRISCV64::GenerateNop() { LOG(FATAL) << "Unimplemented"; }
+void CodeGeneratorRISCV64::GenerateNop() {
+  __ Nop();
+}
 
 void CodeGeneratorRISCV64::GenerateImplicitNullCheck(HNullCheck* instruction) {
   UNUSED(instruction);